Space Technology
Satellite technology
Satellite is an artificial object which has been intentionally placed into orbit. Such objects are
sometimes called artificial satellites to distinguish them from natural satellites such as Earth's
Moon.
Soviet Union in 1957 launched the world's first artificial satellite, the Sputnik 1. Since then,
thousands of satellites have been launched into orbit around the Earth. Some satellites, notably
space stations, have been launched in parts and assembled in orbit. More than 40 countries
originate artificial satellites and have used the satellite launching capabilities of ten nations. About
a thousand satellites are currently operational, whereas thousands of unused satellites and satellite
fragments orbit the Earth as space debris. A few space probes have been placed into orbit around
other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn,
Vesta, Eros, Ceres, and the Sun.
A satellite is a small body revolving around a plane. The moon is a satellite of the earth. As the
earth revolves in its orbit around the sun, the moon revolves around the earth. The satellites of
other planets are also known as ‘moons’. Earth has only one moon, whereas Saturn has nine,
Jupiter has twelve, Mars and Neptune have two each and Uranus has five. The only planets no
moon are known are Mercury, Venus and Pluto. Thus, Jupiter has maximum number of moons.
The satellites, like planets, have no light of their own. They shine by reflecting the light of the sun.
A satellite is held by the gravitational force of the planet and revolves around it.
Moon – the earth’s Satellite
Our moon is about 3.86* 105 Kilometres away from the earth and is about 3476 kilometres in
diameter. It takes 271/3 days to complete one revolution around the earth. Because of its small size
the moon’s gravitational force is only one-sixth as great as the earths and the moon is unable to
hold gases. Its surface has large number of cracters and mountains and is covered with hard and
loose dirt. On the moon, days are very hot while nights are very cold. The large temperature
variation is due to the absence of atmosphere on the moon. The atmosphere acts as a blanket by
absorbing radiations and keeps the body warmer. Since the moon is closer to the earth, it appears
to be much bigger than the stars.
Satellites are used for a large number of purposes. Common types include military and civilian
Earth observation satellites, communications satellites, navigation satellites, weather satellites, and
research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits
vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Wellknown (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.
About 6,600 satellites have been launched. The latest estimates are that 3,600 remain in orbit. Of
those, about 1,000 are operational; the rest have lived out their useful lives and are part of the space
debris. Approximately 500 operational satellites are in low-Earth orbit, 50 are in medium-Earth
orbit (at 20,000 km), the rest are in geostationary orbit (at 36,000 km).
Satellites are propelled by rockets to their orbits. Usually the launch vehicle itself is a rocket lifting
off from a launch pad on land. In a minority of cases satellites are launched at sea (from a submarine
or a mobile maritime platform) or aboard a plane (see air launch to orbit).
Satellites come in many shapes and sizes. But most have at least two parts in common - an antenna
and a power source. The antenna sends and receives information, often to and from Earth. The
power source can be a solar panel or battery. Solar panels make power by turning sunlight into
electricity.
Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend
many tasks, such as power generation, thermal control, telemetry, attitude control and orbit
control.
Types
1. Astronomical Satellites
These satellites are used for observation of distant planets, galaxies, and other outer space objects.
2. Biosatellites
Satellites which are designed to carry living organisms, generally for scientific experimentation.
3. Communication satellites
A satellite placed in orbit round the earth in order to relay television, radio, and telephone signals.
Modern communications satellites typically use geosynchronous orbits,Molniya orbits or Low
Earth orbits.
4. Earth observation satellites
Satellites that are used for environmental monitoring, meteorology, map making etc. are termed
as Earth observation satellites
5. Killer Satellites
Satellites that are designed to destroy enemy warheads, satellites, and other space assets are known
as killer satellites.
6. Navigational satellites
Navigation satellites are satellites which use radio time signals transmitted to enable mobile
receivers on the ground to determine their exact location. The relatively clear line of sight between
the satellites and receivers on the ground, combined with ever-improving electronics, allows
satellite navigation systems to measure location to accuracies on the order of a few meters in real
time.
7. Spaceships (Crewed spacecraft)
Spaceships are larger satellites designed to carry a crew into interstellar space.
8. Miniaturized satellites
These satellites are usually low masses and small sizes. They are again classified in to
minisatellite(500-100kg), microsatellite (below 100 kg), nanosatellite (below 10 kg).
9. Reconnaissance satellites
Reconnaissance satellites are Earth observation satellite or communications satellite deployed for
military or intelligence applications.
10. Recovery satellites
Satellites that provide a recovery of reconnaissance, biological, space-production and other
payloads from orbit to Earth are known as recovery satellites.
11. Space stations
Space stations are large artificial satellite used as a long-term base for manned operations in space.
These are designed for medium-term living in orbit, for periods of weeks, months, or even years.
12. Tether satellites
Satellites which are connected to another satellite by a thin cable called a tether are referred as
tether satellites.
13. Weather satellites
Weather satellites are primarily used to monitor Earth's weather and climate.
Satellite Orbit
There are many different satellite orbits that can be used. The ones that receive the most attention
are the geostationary orbit used as they are stationary above a particular point on the Earth. The
first satellite, Sputnik 1, was put into orbit around Earth and was therefore in geocentric orbit. In
fact this is most common type of orbit with approximately 2,465 artificial satellites orbiting the
Earth.
The orbit that is chosen for a satellite depends upon its application. Many communications
satellites similarly use a geostationary orbit. Other satellite systems such as those used for satellite
phones may use Low Earth orbiting systems. Similarly satellite systems used for navigation like
Navstar or Global Positioning (GPS) system occupy a relatively low Earth orbit. Geocentric orbits
may be further classified by their altitude, inclination and eccentricity.
Centric classifications
1. Geocentric orbit
Geocentric orbits are orbit around the planet Earth, such as the Moon or artificial satellites.
Currently there are approximately 1,071artificial satellites orbiting the Earth.
2. Heliocentric orbit
Heliocentric orbits are orbit around the Sun. All planets, comets, and asteroids in our solar
system are in such orbits, as are many artificial satellites and pieces of space debris.
3. Areocentric orbit
An orbit around the planet Mars, such as by moons or artificial satellites.
The general structure of a satellite is that it is connected to the earth stations that are present on
the ground and connected through terrestrial links.
Altitude classifications
1. Low Earth orbit (LEO)
Geocentric orbits ranging in altitude from -0.428 km - 2,000 km (1,200 mi)
2. Medium Earth orbit (MEO)
They are also known as an intermediate circular orbit. Geocentric orbits ranging in altitude from
2,000 km (1,200 mi) - 35,786 km (22,236 mi) .
3. Geosynchronous Orbit (GEO)
Geocentric circular orbit with an altitude of 35,786 kilometres (22,236 mi). A geosynchronous
orbit is an orbit around the Earth with an orbital period of one sidereal day, intentionally matching
the Earth's sidereal rotation period (approximately 23 hours 56 minutes and 4 seconds). The speed
is approximately 3,000 metres per second (9,800 ft/s).
4. High Earth orbit (HEO)
Geocentric orbits above the altitude of geosynchronous orbit 35,786 km (22,236 mi) are termed
as High Earth Orbit (HEO).
Inclination classifications
1. Polar orbits are special Low Earth Orbits in which the satellite travels north-south over the
Earth's poles, rather than in the more usual east-west direction. The big advantage of this is that
in a single day they can observe the entire Earth as it rotates underneath them. It has an inclination
of (or very close to) 90 degrees.
2. Polar sun synchronous orbit
This orbit is a special case of the polar orbit. Like a polar orbit, the satellite travels from the north
to the south poles as the Earth turns below it. In a sun-synchronous orbit, though, the satellite
passes over the same part of the Earth at roughly the same local time each day. This can make
communication and various forms of data collection very convenient. For example, a satellite in a
sun-synchronous orbit could measure the air quality of Ottawa at noon. There is a special kind of
sun-synchronous orbit called a dawn-to-dusk orbit. In a dawn-to-dusk orbit, the satellite trails the
Earth's shadow. When the sun shines on one side of the Earth, it casts a shadow on the opposite
side of the Earth. (This shadow is night-time.) Because the satellite never moves into this shadow,
the sun's light is always on it (sort of like perpetual daytime). Since the satellite is close to the
shadow, the part of the Earth the satellite is directly above is always at sunset or sunrise. That is
why this kind of orbit is called a dawn-dusk orbit. This allows the satellite to always have its solar
panels in the sun.
Radarsat is an example of a satellite in a low sun-synchronous orbit. Radarsat is in orbit 798
kilometres above the Earth, at an angle of inclination of 98.6 degrees to the equator as it circles the
globe from pole to pole. Radarsat relies on its dawn-to-dusk orbit to keep its solar panels facing
the sun almost constantly. Radarsat can therefore rely mostly on solar power and not on batteries.
Eccentricity classifications
1. Circular Orbit
Though no orbit is perfectly circular, the general name for any orbit that is not highly elliptical (egg-shaped)
is circular. Circular orbits have an eccentricity of 0.

Hohmann transfer orbit:
An orbit that moves a spacecraft from one approximately circular orbit, usually the orbit of a planet,
to another, using two engine impulses. The perihelion of the transfer orbit is at the same distance
from the Sun as the radius of one planet's orbit, and the aphelion is at the other. The two rocket
burns change the spacecraft's path from one circular orbit to the transfer orbit, and later to the
other circular orbit. This maneuver was named after Walter Hohmann.
2. Elliptic orbit
An orbit with an eccentricity greater than 0 and less than 1 whose orbit traces the path of an ellipse .

Geosynchronous transfer orbit
An elliptic orbit where the perigee is at the altitude of a Low Earth orbit (LEO) and the apogee at the
altitude of a geosynchronous orbit .

Geostationary transfer orbit
An elliptic orbit where the perigee is at the altitude of a Low Earth orbit (LEO) and the apogee at the altitude
of a geostationary orbit .

Molniya orbit
A highly elliptic orbit with inclination of 63.4° and orbital period of half of a sidereal day (roughly 12
hours). Such a satellite spends most of its time over two designated areas of the planet (specifically Russia
and the United States).

Tundra orbit
A highly elliptic orbit with inclination of 63.4° and orbital period of one sidereal day (roughly 24 hours).
Such a satellite spends most of its time over a single designated area of the planet.
Special classifications
1. Moon orbit
An orbit with an average altitude of 384,403 kilometers (238,857 mi), elliptical–inclined orbit .
2. Sun-synchronous orbit
An orbit which combines altitude and inclination in such a way that the satellite passes over any given point of
the planets' surface at the same local solar time. Such an orbit can place a satellite in constant sunlight and is
useful for imaging, spy, and weather satellites.
Satellite subsystem
A satellite usually has five major subsystems: attitude and orbit control system (AOCS), telemetry, tracking,
command, and Monitoring (TTC&M), power system, communication subsystems, and satellite antennas.
Attitude and Orbit Control System (AOCS)
The AOCS consists of rocket motors to move the satellite back to the correct orbit when external forces
cause it to drift and gas jets or internal devices to control the attitude of the satellite.
Telemetry, Tracking, Command, and Monitoring (TTC&M)
The TTC&M system is partly on the satellite and partly at the controlling earth station. The telemetry
system sends data received from sensors on the satellite to monitor the satellite’s health, via telemetry link
to the controlling earth station. The tracking system at the earth station provides information on the range,
elevation, and azimuth of the satellite needed in computing orbital elements. Based on telemetry data
received from the satellite through the telemetry system and orbital data obtained from the tracking system,
the control system corrects the antenna positioning and communication system configuration to suit
current traffic requirements and to operate switches on the satellite.
Power System
Most communication satellites derive their electric power from solar cells. The power is used by the
communication system, mainly in its transmitter, and other electrical systems on the satellite. The latter use
is called housekeeping.
Communication Subsystems
The communication subsystem is the major component of a communication satellite, although, frequently,
the communication equipment is only a small part of the weight and volume of the whole satellite. It is
usually composed of one or more antennas and a set of receivers and transmitters that amplify and retransmit
the incoming signal. A receiver-transmitter unit is called as a transponder.
There are other subsystems that are not listed above, but which are essential to the operation of the
satellite- for example
Thermal control subsystem
The thermal control subsystem helps protect electronic equipment from extreme temperatures due
to intense sunlight or the lack of sun exposure on different sides of the satellite's body (e.g. Optical
Solar Reflector).
Structural subsystem
The structural subsystem provides the mechanical base structure with adequate stiffness to
withstand stress and vibrations experienced during launch, maintain structural integrity and
stability while on station in orbit, and shields the satellite from extreme temperature changes and
micro-meteorite damage.
Telemetry subsystem
The telemetry subsystem (aka Command and Data Handling, C&DH) monitors the on-board
equipment operations, transmits equipment operation data to the earth control station, and
receives the earth control station's commands to perform equipment operation adjustments.
First satellites of countries:
First satellites of countries including those launched indigenously or with the help of others
Year of first
Country
Soviet
(
launch
Union 1957
Russia)
Payloads in orbit as of
First satellite
Sputnik
April 2016
1
1457
(1992)
(Kosmos 2175)
United States
1958
Explorer 1
1252
United Kingdom
1962
Ariel 1
40
Canada
1962
Alouette 1
43
Italy
1964
San Marco 1
22
France
1965
Astérix
60
Australia
1967
WRESAT
14
Germany
1969
Azur
49
Japan
1970
Ōsumi
153
China
1970
Dong Fang Hong I
210
Netherlands
1974
ANS
5
First satellites of countries including those launched indigenously or with the help of others
Country
Year of first
launch
First satellite
Payloads in orbit as of
April 2016
Spain
1974
Intasat
9
India
1975
Aryabhata
65
Indonesia
1976
Palapa A1
13
Czechoslovakia
1978
Magion 1
5
Bulgaria
1981
Intercosmos Bulgaria 1300
1
Saudi Arabia
1985
Arabsat-1A
12
Brazil
1985
Brasilsat A1
15
Mexico
1985
Morelos 1
9
Sweden
1986
Viking
11
Israel
1988
Ofeq 1
11
Luxembourg
1988
Astra 1A
5
Argentina
1990
Lusat
9
First satellites of countries including those launched indigenously or with the help of others
Country
Year of first
launch
First satellite
Payloads in orbit as of
April 2016
Hong Kong
1990
AsiaSat 1
9
Pakistan
1990
Badr-1
3
South Korea
1992
Kitsat A
11
Portugal
1993
PoSAT-1
1
Thailand
1993
Thaicom 1
7
Turkey
1994
Turksat 1B
8
Czech Republic
1995
Magion 4
5
Ukraine
1995
Sich-1
6
Malaysia
1996
MEASAT
6
Norway
1997
Thor 2
3
Philippines
1997
Mabuhay 1
2
Egypt
1998
Nilesat 101
4
First satellites of countries including those launched indigenously or with the help of others
Year of first
Country
launch
First satellite
Payloads in orbit as of
April 2016
Chile
1998
FASat-Bravo
2
Singapore
1998
ST-1
3
Taiwan
1999
ROCSAT-1
8
Denmark
1999
Ørsted
4
South Africa
1999
SUNSAT
2
2000
Thuraya 1
6
Morocco
2001
Maroc-Tubsat
1
Tonga
2002
Esiafi 1 (former Comstar D4)
1
Algeria
2002
Alsat 1
1
Greece
2003
Hellas Sat 2
2
Cyprus
2003
Hellas Sat 2
2
Nigeria
2003
Nigeriasat 1
4
United
Emirates
Arab
First satellites of countries including those launched indigenously or with the help of others
Country
Year of first
launch
First satellite
Payloads in orbit as of
April 2016
Iran
2005
Sina-1
1
Kazakhstan
2006
KazSat 1
2
Colombia
2007
Libertad 1
1
Mauritius
2007
Rascom-QAF 1
2
Vietnam
2008
Vinasat-1
3
Venezuela
2008
Venesat-1
2
Switzerland
2009
SwissCube-1
2
Isle of Man
2011
ViaSat-1
1
Poland
2012
PW-Sat
2
Hungary
2012
MaSat-1
1
Romania
2012
Goliat
1
Belarus
2012
BKA (BelKA-2)
N/A
First satellites of countries including those launched indigenously or with the help of others
Country
Year of first
launch
First satellite
Payloads in orbit as of
April 2016
North Korea
2012
Kwangmyŏngsŏng-3 Unit 2
1
Azerbaijan
2013
Azerspace
1
Austria
2013
TUGSAT-1/UniBRITE
2
Bermuda
2013
Ecuador
2013
NEE-01 Pegaso
1
Estonia
2013
ESTCube-1
1
Jersey
2013
O3b-1,-2,-3,-4
4
Qatar
2013
Es'hailSat1
1
Peru
2013
PUCPSAT-1
1
Bolivia
2013
TKSat-1
1
Lithuania
2014
LituanicaSAT-1 and LitSat-1
2
Belgium
2014
QB50P1 and QB50P2
2
Bermudasat 1 (former EchoStar
VI)
1
First satellites of countries including those launched indigenously or with the help of others
Country
Year of first
launch
First satellite
Antelsat
Payloads in orbit as of
April 2016
Uruguay
2014
Iraq
2014
Turkmenistan
2015
TurkmenAlem52E/MonacoSAT
1
Laos
2015
Laosat-1
1
Tigrisat
1
1
End of Mission
When satellites reach the end of their mission, satellite operators have the option of de-orbiting
the satellite, leaving the satellite in its current orbit or moving the satellite to agraveyard orbit.
Historically, due to budgetary constraints at the beginning of satellite missions, satellites were rarely
designed to be de-orbited. One example of this practice is the satellite Vanguard 1. Launched in
1958, Vanguard 1, the 4th manmade satellite put in Geocentric orbit, was still in orbit as of August
2009.
Instead of being de-orbited, most satellites are either left in their current orbit or moved to
a graveyard orbit. As of 2002, the FCC requires all geostationary satellites to commit to moving to
a graveyard orbit at the end of their operational life prior to launch. In cases of uncontrolled deorbiting, the major variable is the solar flux, and the minor variables the components and form
factors of the satellite itself, and the gravitational perturbations generated by the Sun and the Moon
(as well as those exercised by large mountain ranges, whether above or below sea level). The
nominal breakup altitude due to aerodynamic forces and temperatures is 78 km, with a range
between 72 and 84 km. Solar panels, however, are destroyed before any other component at
altitudes between 90 and 95 km.
Types
1. Communication Satellite
Brief History of Satellite Communications
Writer Arthur C. Clarke first suggested the idea of communications satellites in geosynchronous
in the October 1945 issue of Wireless World. The article described the fundamentals behind the
deployment of artificial satellites in geostationary orbits for the purpose of relaying radio signals.
Thus, Arthur C. Clarke is often quoted as being the inventor of the communications satellite and
the term 'Clarke Belt' employed as a description of the orbit.
The first satellite to contain a radio transmitter was the USSR’s Sputnik, launched in 1957. The
U.S rushed to end a Sputnik-like transmitter into space in early 1958. Later that same year the U.S
put into orbit the first radio relay capable of both transmitting and receiving messages (called
Project SCORE). The military continued to develop military satellites and, today, military
command and control operations in many countries rely extensively on satellites, although the
functions of many of them remain secret. These satellites have included spy satellites, those used
for voice and data communication, weather information, navigational information, and the Global
Positioning System (GPS).
Bell Labs and NASA launched the first satellite for civilian communication in 1960. Called Echo
I, it consisted of a large plastic balloon which was inflated in space. Its surface, which was coated
in a thin layer of aluminum, reflected microwave communication beams aimed at it. In 1962 Echo
I was used to reflect microwave signals carrying images and telephone conversations. Satellites also
went international in 1962, as the United Kingdom and Canada both sponsored launches that
year.
Beginning in 1961, NASA sponsored more advanced “active” telecommunication satellites
containing electronic relays. The idea was to launch numerous satellites into orbit and build
corresponding ground stations wherever they were needed. Telephone, television, facsimile, and
data could then be efficiently transmitted anywhere at low cost. The first to be launched was
AT&T’s Telstar I on 10 July 1962. Telstar I retransmitted TV signals from the U.S to a receiving
station in France that same day. It was also the first satellite to use an important new type of
microwave transmitting device called the traveling wave tube. This device became a common
feature in later satellites.
Satellites like Telstar I marked a new age, but had many limitations. Non-geosynchronous satellites
(those that did not move with the earth) such as Telstar I passed across the sky and then disappeared
over the horizon. For a reliable satellite telecommunication system based on a non-geosynchronous
satellite to work, either numerous ground stations needed to be strung across a vast distance on the
earth, or a string of satellites were required. Otherwise contact with the satellite would be lost as
soon as it dipped below the horizon. Telstar I, for example, was available for use by the stations in
the U.S and Europe only about 100 minutes per day.
In 1965 a new type of satellite called Early Bird I was launched. This was the first geosynchronous
satellite, meaning that the satellite’s orbital speed matched the movement of the earth, making it
appear stationary in the sky. Because it never dipped below the horizon, Early Bird I could provide
150 simultaneous telephone links or one television link. Geosynchronous satellites also simplified
the problem of space-to-ground communication, and most of today’s satellites operate this way.
By 1969 global satellite coverage was achieved just days before the first moon landing, which made
worldwide live television broadcast of the event possible.
New uses for satellites emerged in 1970s, such as their use as a navigational aid for commercial
ships. Another new use was the so-called domestic satellite, which enhanced or even bypassed,
existing land-based national networks rather than providing international links across the oceans.
Canada was the first nation to use domestic satellites to serve vast rural areas poorly served by the
telephone system. In subsequent years, many other countries purchased or leased satellites to avoid
the high expense of building ground-based telephone, radio, or television networks. Indonesia was
the first to do this in 1976.
In the U.S, domestic satellites were mainly used by television broadcasters. In the late 1970s and
1980s, new “satellite” networks such as Home Box Office and Turner Network Television
emerged, using satellites to create at a low cost the kind of expensive land-based networks built
earlier by NBC, ABC, and CBS. Ground stations operated by local cable companies receive these
signals and retransmit them over coaxial cable to homes. Since the 1980s, many American
consumers have turned to new satellites broadcasting services, which transmit directly to receiving
“dish” antennas small enough to be mounted outside the home. This is possible because
transmitters inside the satellites are much more powerful, and thus a smaller, less sensitive antenna
can be used.
Points to be noted,
 1945 Arthur C. Clarke publishes an essay about “Extra Terrestrial Relays”  1957 first satellite SPUTNIK.  1960 first reflecting communication satellite ECHO.  1963 first geostationary satellite SYNCOM .  1965 first commercial geostationary satellite Satellit “Early Bird”(INTELSAT I): 240 duplex telephone channels or 1 TV channel, 1.5 years lifetime.  1976 three MARISAT satellites for maritime communication  1982 first mobile satellite telephone system INMARSAT‐A  1988 first satellite system for mobile phones and data communication INMARSAT‐C  1993 first digital satellite telephone system 1998 global satellite systems for small mobile phones
A communications satellite is an artificial satellite that relays and amplifies radio
telecommunications signals via a transponder; it creates a communication channel between a
source transmitter and a receiver at different locations on Earth. Communication satellites are
widely used for television, telephone, radio, internet, and military applications. Approximately
2,000 communications satellites orbiting Earth, used by both private and government
organization.
Structure
Communication satellite consists of following subsystem:
1. Communication Payload, it mainly composed of transponders, antennas, and switching
systems
2. Engines used to bring the satellite to its desired orbit
3. Station Keeping Tracking and stabilization subsystem ,these are used to keep the
satellite in the correct orbit, with the help of antennas pointed in the right direction, and
its power system pointed towards the direction of sun.
4. Power subsystem, satellite system gets it power by the use of power subsystem, they are
normally composed of solar cells, and batteries that maintain power during solar eclipse.
5. Command and Control subsystem, which helps in maintaining communications with
ground control stations. The ground control earth stations monitor the satellite
performance and control its functionality during various phases of its life-cycle.
Frequency Allocation for satellite systems
Frequency Allocation for satellite systems is carried out by International Telecommunication
Union (ITU) and it is a complicated process which requires international coordination and
planning.
In order to facilitate frequency planning, the world is divided into three regions:
 Region 1: Europe, Africa, what was formerly the Soviet Union, and Mongolia.
 Region 2: North and South America and Greenland.
 Region 3: Asia (excluding region 1 areas), Australia, and the southwest Pacific.
Allocation for Different Services

Fixed satellite service (FSS)
Fixed service satellite is a type of satellite which provides links for existing telephone
networks used for transmitting television signals to cable companies. Fixed service satellite
generally have a low power output and larger dish-style antennas are required for reception.
Fixed service satellites have less power than direct broadcasting satellites (DBS).

Broadcasting satellite service (BSS)
These types of satellites provides direct broadcast to homes.
Mobile satellite services
This includes services for land mobile, maritime mobile, aeronautical mobile

 Radionavigation-satellite service
 Meteorological-satellite service
 Amateur-satellite service
Satellite Orbits
Communication satellites have one of three primary types of orbit.
1. Low Earth Orbiting (LEO) satellites
A low Earth orbit (LEO) are placed 160 to 2,000 kilometers. Since the LEOs circulate on a lower
orbit, hence they exhibit a much shorter period that is 95 to 120 minutes. Compare to
geostationary satellites Low-Earth-orbiting satellites are less expensive to launch into orbit. Due to
lower latency these satellites are mainly used in remote sensing and providing mobile
communication services.
2. Medium Earth Orbit (MEO)
MEOs can be positioned somewhere between LEOs and GEO (ie, between 2,000 and 35,786
kilometres above the earth’s surface) both in terms of their advantages and disadvantages. These
satellites are similar to LEO satellites in functionality and are visible for much longer periods of
time than LEO satellites, usually between 2 and 8 hours. These satellites move more slowly relative
to the earth’s rotation allowing a simpler system design. MEO satellites make the trip around earth
in anywhere from 2–12 hours, which provides better coverage to wider areas than that provided
by LEOs.
One of the main disadvantages is that, due to the larger distance to the earth, delay increases to about 70–
80 ms. the satellites need higher transmit power and special antennas for smaller footprints.
Example:
In 1962, the first communications satellite, Telstar, was launched. It was a medium earth orbit
satellite designed to help facilitate high-speed telephone signals. One of the major drawback which
was found out is that its orbital period of about 2.5 hours did not match the Earth's rotational
period of 24 hours, continuous coverage was impossible. It was apparent that multiple MEOs
needed to be used in order to provide continuous coverage.
3. Geostationary orbits (GEO)
GEO satellites are synchronous with respect to earth. Looking from a fixed point from Earth, these satellites appear to be stationary. These satellites are placed in the space in such a way that only three satellites are sufficient to provide connection throughout the surface of the Earth (that is; their footprint is covering almost 1/3rd of the Earth). The orbit of these satellites is circular. There are three conditions which lead to geostationary satellites. Lifetime expectancy of these satellites is 15 years. 1) The satellite should be placed 37,786 kms (approximated to 36,000 kms) above the surface of the earth. 2) These satellites must travel in the rotational speed of earth, and in the direction of motion of earth, that is eastward. 3) The inclination of satellite with respect to earth must be 00. Geostationary satellite in practical is termed as geosynchronous as there are multiple factors which make these satellites shift from the ideal geostationary condition. 1) Gravitational pull of sun and moon makes these satellites deviate from their orbit. Over the period of time, they go through a drag. (Earth’s gravitational force has no effect on these satellites due to their distance from the surface of the Earth.) 2) These satellites experience the centrifugal force due to the rotation of Earth, making them deviate from their orbit. 3) The non‐circular shape of the earth leads to continuous adjustment of speed of satellite from the earth station. These satellites are used for TV and radio broadcast, weather forecast and also, these satellites are operating as backbones for the telephone networks. Disadvantages of GEO: Northern or southern regions of the Earth (poles) have more problems
receiving these satellites due to the low elevation above a latitude of 60°, i.e., larger antennas are
needed in this case. Shading of the signals is seen in cities due to high buildings and the low
elevation further away from the equator limit transmission quality. The transmit power needed is
relatively high which causes problems for battery powered devices. These satellites cannot be used
for small mobile phones. The biggest problem for voice and also data communication is the high
latency as without having any handovers, the signal has to at least travel 72,000 kms. Due to the
large footprint, either frequencies cannot be reused or the GEO satellite needs special antennas
focusing on a smaller footprint. Transferring a GEO into orbit is very expensive.
Examples:

The first geostationary satellite was Syncom 3, launched on August 19, 1964, and used for communication across the Pacific starting with television coverage of the 1964 Summer Olympics. Shortly after Syncom 3, Intelsat I, aka Early Bird, was launched on April 6, 1965 and placed in orbit at 28° west longitude. It was the first geostationary satellite for telecommunications over the Atlantic Ocean. 
On November 9, 1972, Canada's first geostationary satellite serving the continent, Anik
A1, was launched by Telesat Canada, with the United States following suit with the launch
of Westar 1 by Western Union on April 13, 1974.

On May 30, 1974, the first geostationary communications satellite in the world to be threeaxis stabilized was launched: the experimental satellite ATS-6 built for NASA.

After the launches of the Telstar through Westar 1 satellites, RCA Americom (later GE
Americom, now SES) launched Satcom 1 in 1975. It was Satcom 1 that was instrumental
in helping early cable TV channels such as WTBS (now TBS Superstation), HBO, CBN
(now ABC Family) and The Weather Channel become successful, because these channels
distributed their programming to all of the local cable TV headends using the satellite.
Additionally, it was the first satellite used by broadcast television networks in the United
States, like ABC, NBC, and CBS, to distribute programming to their local affiliate stations.
Satcom 1 was widely used because it had twice the communications capacity of the
competing Westar 1 in America (24 transponders as opposed to the 12 of Westar 1),
resulting in lower transponder-usage costs. Satellites in later decades tended to have even
higher transponder numbers.
APPLICATION
1. Weather Forecasting
Certain satellites are specifically designed to monitor the climatic conditions of earth. They
continuously monitor the assigned areas of earth and predict the weather conditions of that
region. This is done by taking images of earth from the satellite. These images are transferred
using assigned radio frequency to the earth station. (Earth Station: it‟s a radio station located
on the earth and used for relaying signals from satellites.) These satellites are exceptionally
useful in predicting disasters like hurricanes, and monitor the changes in the Earth's vegetation,
sea state, ocean color, and ice fields.
2. Radio and TV Broadcast
These dedicated satellites are responsible for making 100s of channels across the globe available
for everyone. They are also responsible for broadcasting live matches, news, world-wide radio
services. These satellites require a 30-40 cm sized dish to make these channels available globally.
3. Military Satellites
These satellites are often used for gathering intelligence, as a communications satellite used for
military purposes, or as a military weapon. A satellite by itself is neither military nor civil. It is
the kind of payload it carries that enables one to arrive at a decision regarding its military or
civilian character.
4. Navigation Satellites
The system allows for precise localization world-wide, and with some additional techniques,
the precision is in the range of some meters. Ships and aircraft rely on GPS as an addition to
traditional navigation systems. Many vehicles come with installed GPS receivers. This system
is also used, e.g., for fleet management of trucks or for vehicle localization in case of theft.
5. Global Telephone
One of the first applications of satellites for communication was the establishment of
international telephone backbones. Instead of using cables it was sometimes faster to launch a
new satellite. But, fiber optic cables are still replacing satellite communication across long
distance as in fiber optic cable, light is used instead of radio frequency, hence making the
communication much faster (and of course, reducing the delay caused due to the amount of
distance a signal needs to travel before reaching the destination.). Using satellites, to typically
reach a distance approximately 10,000 kms away, the signal needs to travel almost 72,000 kms,
that is, sending data from ground to satellite and (mostly) from satellite to another location on
earth. This cause’s substantial amount of delay and this delay becomes more prominent for
users during voice calls.
Major differences between LEO, MEO and GEO satellite systems:
Parameter
LEO
MEO
GEO
Satellite Height
500-1500 km
5000-12000 km 35,800 km
Orbital Period
10-40 minutes
2-8 hours
24 hours
Number of Satellites
40-80
8-20
3
Satellite Life
Short
Long
Long
Number of Handoffs
High
Low
Least(none)
Gateway Cost
Very Expensive Expensive
Cheap
Propagation Loss
Least
Highest
High
List of communications satellite firsts:
Milestones in the history of communications satellites.
Satellite
First
Launched
Sputnik 1
First satellite with radio transmitter
October 4, 1957
First
communications
satellite
First test of a space communications relay
Project SCORE
system
First
(recorded)
voice
Nation
transmission
(US
December
18,
1958
President Dwight Eisenhower)
TIROS-1
Echo 1
First satellite to transmit television images from
space (weather)
First passive reflector communications satellite
April 1, 1960
August 12, 1960
First active repeater communications satellite
Courier 1B
First communications satellite powered by solar October 4, 1960
cells to recharge storage batteries
First
OSCAR 1
amateur
radio
satellite
First satellite ejected into orbit as a secondary
launch payload
December
12,
1961
First active, direct-relay communications satellite
Telstar 1
First satellite to relay television, telephone and
high-speed
data
communications
July 10, 1962
First transatlantic television
First
Relay 1
transpacific
television
(news
of
the assassination and funeral procession of US December
President
John
F
13,
Kennedy) 1962
First tandem satellite broadcast (with Syncom 3)
Syncom 2
First communications satellite in geosynchronous
orbit
July 16, 1963
First communications satellite in geostationary
orbit
Syncom 3
First
Olympic
broadcast
to
international August 19, 1964
audiences
First tandem satellite broadcast (with Relay 1)
First amateur radio communications satellite
OSCAR-III
(relay/transponder); first OSCAR powered by March 9, 1965
solar cells
Molniya
Intelsat I
First Soviet communications satellite (military);
highly elliptical orbit
First commercial communications satellite in
geosynchronous orbit
April 23, 1965
April 6, 1965
Orbita
First national TV network based on satellite
television (Soviet Union)
November 1967
First satellite-based search and rescue system
Nimbus 3
First satellite to locate and command remote April 14, 1969
weather stations to transmit data back to satellite
Anik 1
Westar 1
First domestic communications satellite system November
using geosynchronous orbit (Canada)
First
American
domestic
9,
1972
commercial
geostationary communications satellite
April 13, 1974
First geostationary communications satellite to
be
ATS-6
three-axis
stabilized
First experimental Direct Broadcast Satellite May 30, 1974
First satellite to provide communications relay
services for other spacecraft (Nimbus 6)
Symphonie
AO-6 & AO-7
First geostationary communications satellite with December
unified propulsion system for station-keeping
19,
1974
First satellite-to-satellite communications relay January
1975
(ground -> AO-7 -> AO-6 -> ground)
(occurred)
Aryabhata
First Indian satellite
April 19, 1975
Palapa A1
First Indonesian communications satellite
July 8, 1976
First serial Direct-To-Home TV communication
Ekran
satellite
First Soviet operational geosynchronous satellite
October
1976
26,
SBS-3
First commercial use of the US Space Shuttle
Tracking
data
and
relay
satellite-A
Arabsat-1A
First satellite of first full-time communications
relay network for other spacecraft
November
11,
1982
April 4, 1983
First communications satellite for the Arab February
2,
League
1985
Morelos I
First communications satellite for Mexico
June 17, 1985
Badr-1
First communications satellite of Pakistan
July 16, 1990
Turksat 1B
First communications satellite for Turkey
August 10, 1994
Iridium 1
First satellite for satellite telephone service
May 5, 1997
AO-40
Artemis
SuitSat
ARSAT-1
First satellite to use GPS for navigation and November
attitude determination in HEO
First
demonstration
communication
of
inter-satellite
16,
2000
laser
November
21,
2001
(experiment)
First use of a decommissioned spacesuit as a February
radio satellite
First Argentine
3,
2006 (deployed)
communications satellite in October
geosynchronous orbit
15,
2014 (Launch)
BRIsat
First satellite owned and operated by a bank
October
18,
2016 (Launch)
2. Earth observation satellite
Earth observation satellites are satellites specifically designed for Earth observation from orbit,
similar to spy satellites but intended for non-military uses such as environmental monitoring,
meteorology, map making etc.
Altitudes below 500-600 kilometers are in general avoided, though, because of the significant airdrag at such low altitudes making frequent orbit reboost maneuvres necessary. The Earth
observation satellites ERS-1, ERS-2 and Envisat of European Space Agency as well as the MetOp
spacecraft of EUMETSAT are all operated at altitudes of about 800 km. The Proba-1, Proba-2
and SMOS spacecraft of European Space Agency are observing the Earth from an altitude of about
700 km. The Earth observation satellites of UAE, DubaiSat-1 & DubaiSat-2 are also placed in
Low Earth Orbits (LEO) orbits and providing satellite imagery of various parts of the Earth.
Weather
Satellites that are mainly used for monitoring the weather and climate of the earth are referred as
weather satellite. City lights, fires, effects of pollution, auroras, sand and dust storms, snow cover,
ice mapping, boundaries of ocean currents, energy flows, etc., are other types of environmental
information collected using weather satellites.
Weather satellite images helped in monitoring the volcanic ash cloud from Mount St. Helens and
activity from other volcanoes such as Mount Etna. Smoke from fires in the western United States
such as Colorado and Utah have also been monitored.
1960: NASA launches the first weather satellite, TIROS-1, from Cape Canaveral, Florida.
TIROS, for Television Infrared Observation Satellite, sent the very first TV images from space to
the ground station at Fort Monmouth, New Jersey. The pictures clearly showed the New England
coast and Canada's Maritime Provinces north to the St. Lawrence River. The photos were airlifted
pronto to Washington, D.C., to be presented to President Eisenhower.
TIROS-1 was an aluminum-and-stainless-steel drum measuring 42 inches in diameter, 19 inches
high and weighing 270 pounds. An array of 9,200 solar cells powered its two TV cameras: one
high-res, one low-res. One antenna received control signals from ground stations, and another four
transmitted TV images back to Earth. Two video recorders stored images when the satellite was
out of range of ground stations.
3. Geosynchronous satellite
A geosynchronous satellite is a satellite in geosynchronous orbit, with an orbital period the same
as the Earth's rotation period. A special case of geosynchronous satellite is the geostationary
satellite. Geostationary satellite has geostationary orbit, circular geosynchronous orbit directly
above the Earth's equator. Similarly Tundra elliptical orbit is also another type of geosynchronous
orbit.
One of the remarkable advantage of geosynchronous satellites is that it remains permanently in the
same area of the sky, as viewed from a particular location on Earth, and so permanently within
view of a given ground station. These types of satellites have the special property of remaining
permanently fixed in exactly the same position in the sky, as viewed from any location on Earth,
meaning that ground-based antennas do not need to track them but can remain fixed in one
direction. Such satellites are often used for communication purposes; a geosynchronous network
is a communication network based on communication with or through geosynchronous satellites.
Syncom 2, the world’s first geosynchronous communication satellite, was first launched from
Cape Canaveral, Florida, on a Delta B booster. Syncom 2 was the second of three communication
satellites developed by the Hughes Aircraft Company in the early 1960s.
In1945, English scientist and writer Arthur C. Clarke took Noordung’s theory a step further,
postulating that three spacecraft set equidistant in synchronous orbit would virtually blanket the
planet with continuous radio and television coverage. By the post-Sputnik era of the late 1950s,
when space technology and travel was at fever pitch, Hughes Aircraft Company embarked on this
ambitious new project. Harold Rosen, Donald Williams, and Thomas Hudspeth were assigned the
historic project. By 1961, the has designed and built a prototype satellite, displayed at the Paris Air
Show. In August of that year, they won a $4 million contract from NASA’s Goddard Space Flight
Centre and the United States Department of Defense to build three synchronous communication
satellites. Their objectives; to place a satellite in synchronous orbit, demonstrate on orbit
stationkeeping, and performance communications and engineering tests.
The first Syncom 1, launched in Feb 1963, was lost on the way due to an electronics failure. The
second, Syncom 2, launched on 26 July , was a success. It measured .71 metre in diameter and
weighed 35 kg. During its orbit, NASA conducted voice, teletype, and facsimile tests, as well as
110 public demonstrations to show its capabilities. Syncom 2 also relayed the first successful TV
transmission through geosynchronous satellite. In August 1963, US President John F. Kennedy
telephoned Nigerian Prime Minister Abubakar Balewa abroad USNS Kingsport docked in Lagos
Harbor. It was the first live two-way call between heads of state by satellite. Syncom 2 was followed
up with Syncoms 3 and paved the way for a new Leaset Satellite program. But it was with the
launch of Syncom 2 that global communications were revolutionized in one ambitious project.
List of satellites in geosynchronous orbit:
The table shown below is a list of satellites in geostationary orbit. These satellites are commonly
used for communication purposes, such as radio and television networks, back-haul, and direct
broadcast. Traditional global navigation systems do not use geostationary satellites, but some SBAS
navigation satellites do. A number of weather satellites are also present in geostationary orbits.
180.0°
W
300K
W
and
Radio South Pacific
Gazprom
CIS
Space
Systems
Television
and Internet
Russia
5
October Replaced Intelsa
2011Zenit
2
November
2012Proton-M
t 701
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Intelsat
Broadcasting
W
176.8°
Source
Intelsat-18
Yamal
W
bus
Television
177.1°
176.9°
Satellite
Satellite
Location
Western Hemisphere
2016-04-06
2016-04-06
NSS-9
2015-08-19
Astra-3B
2015-08-19
W
171.1°
W
167.6°
W
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
174.3°
TDRS-10
2015-08-19
TDRS-11
2015-08-19
TDRS-5
2015-08-19
148.0°
EchoStar-
W
1
139.0°
Americom-
W
8
Lockheed
Martin AS- US
7000
Echostar/DI
SH Network Broadcasting
Lockheed
MartinA21
00A
Television
US
28
Direct
SES
Americom
1995,Long
move
March 2E
to77°W soon
to
2009-02-06
December Previously GE-8
C 2000,Ariane
for
GE
radio 24
broadcasting band(Canada,C
and
December Scheduled
19
5G
Americom;
also
known as Aurora
2008-11-20
aribbean,CONU
III;
Alascom
S)
Satcom C-5 in
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Source
bus
Satellite
Satellite
Location
Operator
&AT&T
replaced
March 2001
137.0°
Americom-
W
7
135.0°
Americom-
W
10
134.7°
W
133.0°
W
Lockheed
MartinA21
US
00A
Lockheed
MartinA21
00A
US
SES
Americom
SES
Americom
Television
and
radio
broadcasting
Television
and
Canada,CONU
S,Mexico
Canada,Caribb
Radio ean,CONUS,M
Broadcasting
exico
14 September
2000,Ariane
for GE Americom
5G
5
Previously GE-7
2008-11-20
February
2004,Atlas
II-
2008-11-20
AS
GOES-15
2015-08-19
Galaxy-15
2015-08-19
131.0°
W
Lockheed
AMC-11
MartinA21
US
00A
SES
Americom
Television
and
C
Bandtranspond
19
May Formerly GE-11 ;
Radio ers(Canada,Car 2005, Atlas II- replaced Satcom
Broadcasting
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
24
ibbean,CONUS
AS
2016-04-03
C3
,Mexico)
Orbital
129.0°
W
Galaxy-12
Sciences
Corporatio
Television/R
US
Intelsat
adio
Broadcasting
nStar-2
9 April 2003, replaced
Ariane 5G
failed Galaxy 15
Thales
128.8°
W
Alenia
Ciel-2
SpaceSpa
cebus
4000 C4
Canad
a
Ciel
Satellite
Group
Direct
10
December
Broadcasting
2008,Proton-M
Leased
to Echostar/Dish
Network
2009-02-06
W
AMC-1
2015-08-19
24
Galaxy-13
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
128.6°
HS-601
US
Intelsat
C 1
October
Bandtranspond
2003,Zenit-
ers
3SL
Same satellite as
Horizons-1
2008-11-20
127.0°
W
Horizons-1 HS-601
125.0°
W
Galaxy-14
US
Japan
24
Ku- 1
Satellite
Bandtranspond
2003,Zenit-
Systems
ers
3SL
Orbital
24
Sciences
Bandtranspond
Corporatio
nStar-2
US
Intelsat
ersAmerica
C
North
13
October
Same satellite as
Galaxy-13
2008-11-20
August
2005,SoyuzFG/Fregat
2008-11-20
W
123.0°
W
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
124.9°
AMC-21
Galaxy 18
2015-08-19
LS-1300
US
Intelsat
Television
21
and
2008,
radio North America
broadcasting
May
Zenit-
3SL
Hybrid C/Ku-band
satellite
Hybrid
Galaxy-23
FS-1300
US
Intelsat
Direct
Broadcasting
7
North America
2008-11-19
C/Ku/Ka-
August band satellite; C
2003,Zenit-
band
3SL
referred
121.0°
payload
to
2008-11-26
as
Galaxy-23
W
EchoStar9
FS-1300
US
Echostar/DI
Direct
SH Network Broadcasting
7
North America
August
2003,Zenit3SL
Hybrid
C/Ku/Ka-
band
satellite;
Ku/Ka-band
2008-11-26
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
payload referred
to as EchoStar-9
119.1°
DirecTV-
W
7S
118.8°
EchoStar-
W
7
LS-1300
US
Lockheed
MartinA21
US
00AX
DirecTV
Echostar/DI
Direct
Broadcasting
Direct
SH Network Broadcasting
54
Ku- 4
bandtranspond
2004,
ers
3SL
32
Ku-
bandtranspond
ers
24
W
Anik F3
AstriumEur
Canad
Telesat
Direct
ostar-
a
Canada
Broadcasting
3000S
active
Zenit- transponders at
2008-11-26
this time
February
2002,Atlas IIIB
21
active
transponders at
2008-11-26
this time
C
bandtranspond
EADS
118.7°
21
May 8
ers,
32
Ku-
bandtranspond
ers,
2
Ka-
bandtranspond
ers
11
April
2007,Proton
Ku-Band
leased
toEchostar/Dish
Network
2008-11-26
116.8°
W
SatMex 5
HughesHS
Mexic
-601HP
o
ers,
As of
Remarks
(GMT)
C
bandtranspond
Satmex
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
24
24
5
December
Ku- 1998,Ariane
bandtranspond
2008-11-26
42L
ers
116.1°
SIRIUS-
W
FM-6
115.2°
W
2015-08-19
30
XM-Blues
US
October
2006,Zenit3SL
115.0°
Solidarida
Mexic
W
d-2
o
8
Satmex
October
1994,Ariane
44L
115.0°
W
T
October 56
2011,Proton-M
As of
Remarks
(GMT)
date/rocket
Launch
Type
Coverage
19
115
Ka-band
Transponders
2015-08-19
2015-08-19
West A
MEXSAT-
W
3
W
ViaSat
EUTELSA
114.8°
113.0°
US
Operator
LS-1300
Source
ViaSat-1
bus
Satellite
W
Satellite
Location
115.1°
Satmex 6
2015-08-19
Mexic
o
27
Satmex
May
2006,Ariane 5
ECA
W
T
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
113
2015-08-19
West A
WILDBLU
W
E-1
W
Source
EUTELSA
111.2°
111.1°
bus
Satellite
Satellite
Location
113.0°
Anik F2
111.0°
TERREST
W
AR-1
Boeing 702
US
ViaSat
2015-08-19
Canad
Telesat
Direct
a
Canada
Broadcasting
17
2004,
5G
July
Ariane
Hybrid
C/Ku/Ka-
band satellite
2015-08-19
11
110.0°
EchoStar-
W
10
DirecTV-5
108.0°
W
GOES-3
LS-1300
A2100AXS
LS-1300
US
US
US
Echostar/DI
Direct
SH Network Broadcasting
Echostar/DI
Direct
SH Network Broadcasting
DirecTV
17
2008,
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
EchoStar-
July
Zenit-
2008-11-19
3SL
15
February
2006,Zenit3SL
Direct
7
May
Broadcasting
2002, Proton
32
Ku-
band transponde
rs
2015-08-19
Boeing 702
Canad
Telesat
Direct
a
Canada
Broadcasting
November
2000,Ariane
44L
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Anik F1
21
Hybrid C/Ku-band
satellite; will be
replaced by Anik
F1R
107.3°
W
Direct
Anik F1R
Eurostar-
Canad
Telesat
Broadcasting
8
September
3000
a
Canada
, WAAS PRN
2005,Proton
#138
AMC-18
A2100A
US
Canada,Caribb
SES
Direct
Americom
Broadcasting
SES
Direct
Alaska,CONUS
15
Americom
Broadcasting
,Hawaii
2004,Proton-M
105.0°
ean,CONUS,M
exico
8
Hybrid C/Ku-band
satellite;
will
replace Anik F1
December
2006,Ariane 5
W
Americom15
A2100AXS
US
October
Hybrid
band
Ku/Kasatellite;
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
twin
of
Americom-16
104.6°
W
GOES-14
103.0°
Americom-
W
1
102.9°
SPACEW
W
AY-1
102.8°
DIRECTV-
W
10
2015-08-19
A2100A
US
Boeing 702 US
Canada,Caribb
SES
ean,CONUS,M
Americom
DirecTV
exico
Direct
Broadcasting
8
September Hybrid C/Ku-band
1996,Atlas II-A
26
2005,
satellite
April
Zenit-
3SL
2015-08-19
DIRECTV-
W
12
101.3°
SkyTerra-
W
1
101.2°
DirecTV-
W
4S
101.1°
DirecTV-
W
9S
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
102.8°
2015-08-19
Boeing 702 US
HS-601
LS-1300
US
US
LightSquar
Telecommuni
ed
cations
DirecTV
DirecTV
Direct
Broadcasting
Direct
Broadcasting
14
US
November
2010,ILS Proto
n-M
27
November 48
Ku-
2001,Ariane
band transponde
44LP
rs
13
October
2006,Ariane 5
ECA
101.0°
W
AMC-4
A2100AX
US
SES
ean,Central
Americom
America,CONU
S,Mexico
100.8°
W
99.2°W
99.2°W
DirecTV-8
DIRECTV14
DIRECTV11
LS-1300
US
DirecTV
13
November
1999,Ariane
44LP
Direct
22
Broadcasting
2005,Proton
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Canada,Caribb
Hybrid C/Ku-band
satellite
May Hybrid
Ku/Ka-
band satellite
2015-08-19
2015-08-19
US
AY-2
Galaxy-16
As of
Remarks
(GMT)
November
2005,Ariane 5
ECA
18
97.0°W
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
99.1°W
16
SPACEW
FS-1300
Intelsat
June
2006,Zenit3SL
Maritime and
98.0°W
Inmarsat-4
UK
F3
Inmarsat
Aviation
Communicati
ons
Television
97.0°W
Galaxy-19
FS-1300
US
Intelsat
and
Radio
Broadcasting
Canada,Caribb
11
ean,CONUS,M
2005,Atlas
exico
431
24 C- and 28 Kubandtranspond
ers(North
America)
March
V
2014-04-2
24 September
2008,Zenit3SL
2008-11-20
95.2°W
As of
Remarks
(GMT)
SIRIUS-
2015-08-19
FM-5
DIRECTV-
2015-08-19
15
15
95.0°W
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
96.0°W
Galaxy 3C
US
June
2002,Zenit3SL
95.0°W
93.0°W
INTELSAT
2015-08-19
-30
Galaxy-26
FS-1300
US
15
February
1999,Proton-K
93.1°W
91.1°W
91.0°W
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
94.9°W
SPACEW
2015-08-19
AY-3
GALAXY-
2015-08-19
25
Nimiq 1
Galaxy 17
A2100AX
Spacebus
3000 B3
Canad
Telesat
Direct
20
a
Canada
Broadcasting
1999,Proton
Television
4
and
2007, Ariane 5
US
Intelsat
radio North America
broadcasting
ECA
May
May
32
Ku-
band transponde
rs
Hybrid C/Ku-band
satellite
2008-06-13
89.0°W
Galaxy-28
FS-1300
Intelsat
The Americas
June
2005,Zenit3SL
87.2°W
87.0°W
85.2°W
85.1°W
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
23
Hybrid
C/Ku/Ka-
band
satellite;
launched
as
Telstar 8
TKSAT-1
AMC 3
2015-08-19
A2100A
US
Canada,Caribb
SES
ean,CONUS,M
Americom
exico
4
September Hybrid C/Ku-band
1997,Atlas II-A
XM-5
XMRhythm
satellite
2015-08-19
XM Satellite
Boeing 702 US
Radio
Holdings
Radio
Broadcasting
28
CONUS
February
2005,Zenit3SL
2
Americom16
84.0°W
84.0°W
BrasilSatB3
Brasilsat_
B4
A2100A
A2100AXS
US
US
SES
Direct
Canada,CONU
Americom
Broadcasting
S,Mexico
SES
Direct
Alaska,CONUS
Americom
Broadcasting
,Hawaii
30
As of
Remarks
(GMT)
January
1997,Ariane
44L
17
December
2004,Atlas
V (521)
4
Brazil
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
85.0°W
Americom-
Hybrid
band
Ku/Kasatellite;
twin
of
Americom-15
February
1998,Ariane
44LP
2015-08-19
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
83.8°W
HISPASA
2015-08-19
T-1C
Canada,Caribb
83.0°W
Americom- Spacebus
9
3000B3
US
SES
Direct
ean,Central
7
June Hybrid C/Ku-band
Americom
Broadcasting
America,CONU
2003, Proton
satellite
S,Mexico
Nimiq 2
A2100AX
Canad
Telesat
Direct
29
December Hybrid
a
Canada
Broadcasting
2002,Proton
Telesat
Direct
Canada
Broadcasting
Ku/Ka-
band satellite
82.0°W
Nimiq 3
82.0°W
NIMIQ-4
HS-601
9
1995,
42P
June Previously
Ariane DirecTV-3
forDirecTV
2015-08-19
81W
ARSAT-2
ARSAT-3K
Argent
ina
Data, Internet
ARSAT
and
TV
broadcasting.
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Ku
Band:North
America andSo
uth
Americaexcept
Brazil,C
30 September
2015,Ariane
2015-10-10
5ECA
Band:Americas
80.9°W
SBS-6
HS-393
US
Intelsat
Television
12
and
1990,Ariane
Radio
Broadcasting
80.8°W
79.0°W
October
44L
expected end of
life.
Serves
2008-06-13
Argentina now
AMC-2
2015-08-19
Americom- Spacebus
5
Beyond
2000
US
SES
Canada,CONU
Americom
S,Mexico
28
October
1998,Ariane
44L
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
10 September
Satcom C3
US
1992,Ariane
44LP
78.8°W
78.0°W
SKY
2015-08-19
MEXICO-1
VENESAT
2015-08-19
-1
EchoStar4
A2100AX
US
FS-1300
US
Echostar/DI
Direct
8
May
SH Network Broadcasting
1998, Proton
Echostar/DI
21
spare
77.0°W
EchoStar8
Direct
SH Network Broadcasting
August
2002,Proton
2008-11-19
77.0°W
76.9°W
2015-08-19
R-1
QUETZSA
2015-08-19
T-1
ECHOSTA
2015-08-19
R-8
Galaxy 4R
As of
Remarks
(GMT)
ECHOSTA
19
76.8°W
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
77.1°W
US
April
2000,Ariane
Inclined orbit
42L
76.2°W
INTELSAT
-16
2015-08-19
75.0°W
Brasilsat
B1
Galaxy-9
As of
Remarks
GOES-13
2015-08-19
10
Brazil
August
1994,Ariane
44LP
24
74.9°W
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
76.2°W
US
May
1996,
Delta spare
II (7925)
74.0°W
Horizons-2 STAR Bus
US
Intelsat JS
AT
Television
and
CONUS
Radio Canada
Broadcasting
Caribbean
21
December
2007,Ariane
5GS
20 Ku Xpndrs
2008-06-13
6
FS-1300
US
Echostar/DI
14
Direct
Directv-1R
As of
Remarks
(GMT)
July
2000, Atlas II-
SH Network Broadcasting
2008-11-19
AS
10
72.5°W
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
72.7°W
EchoStar-
US
October
1999,Zenit3SL
Hybrid C/Ku-band
CONUS,Canad
72.0°W
AMC-6
A2100AX
US
satellite;
SES
a,Mexico,Carib
22
Americom
bean,Central
2000,Proton-M
America
a
October portion of the Kuband payload is
dedicated
toSouth America
71.0°W
70.0°W
69.9°W
67.0°W
ARSAT-1
Nahuel 1A
STAR
ONE C2
STAR
ONE C4
AMC-4
ARSAT-3K
Argent
Direct
ina
Broadcasting
Argent
ina
Octobre
Uruguay,Parag
2014,Ariane
uay
5ECA
30
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
71.8°W
Argentina,Chile, 16
First
geostationary
satellite
built
2015-18-08
in Latin America
January
1997,Ariane
44L
2015-08-19
2015-08-19
2015-08-19
70.0°W
65.0°W
65.0°W
63.0°W
AMC-3
Brasilsat_
B4
BrasilsatB2
17
Brazil
August
2000,Ariane
44LP
28
Brazil
March
1995,Ariane
44LP+
2015-08-19
ONE C1
Sul 1
As of
2015-08-19
STAR
Estrela do
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
67.0°W
11
Brazil
January
2004,Zenit3SL
TELSTAR-
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
63.0°W
2015-08-19
14R
62.8°W
ABS-1A
2015-08-19
62.2°W
TDRS-3
2015-08-19
61.5°W
61.3°W
ECHOSTA
2015-08-19
R-16
EchoStar12
17
A2100AXS
US
2003,
V (521)
July
Atlas
Formerly
Rainbow-1,
purchased
from VOOM
61.0°W
58.0°W
55.5°W
3
A2100AX
Hispasat
Intelsat805
US
5
Direct
HS-601HP
October
1997,Atlas
SH Network Broadcasting
II-
AS
4
August
2004,Proton-M
28
US
July
formerly PAS-9
2000,Zenit-3SL
18
Intelsat
June
1998, Atlas IIAS
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Echostar/DI
Spain
Amazonas
Intelsat-9
Source
bus
Satellite
Satellite
Location
61.8°W
EchoStar-
54.0°W
Inmarsat-3
UK
F4
Inmarsat
Aviation
Atlantic Ocean
Communicati
Region
ons
53.0°W
50.0°W
Intelsat-
Intelsat
707
3
Intelsat
705
Intelsat 14
As of
(GMT)
Remarks
2014-04-2
44L
14
March
1996,Ariane 4
March
1995,Atlas
II-
AS
16
45.0°W
June
1997,Arianne
22
Intelsat-
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Maritime and
HS702
US
November
2000,Ariane
5G
formerly
PAS-
1R, and IS-1R
43.1°W
Intelsat-3R HS-601
US
January
1996,Ariane
formerly PAS-3R
44L
22
43.0°W
Intelsat-6B
HS-601HP
December
1998,Ariane
formerly PAS-6B
42L
40.5°W
NSS-806
NSS-10
AS-7000
Nether
lands
28
February
1998,Atlas
II-
AS
Spacebus
3
February
4000 C3
2005,Proton
37.5°W
Telstar-11
US
Inclined orbit
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
12
31.5°W
Intelsat-
Intelsat
903
Intelsat
801
1C
March
2002,Proton-K
March
1997,Ariane
44P
3
Spain
February
2000,Atlas
II-
AS
30.0°W
Hispasat1D
18 September
Spain
2002,Atlas
AS
II-
As of
Remarks
(GMT)
date/rocket
Launch
Type
Coverage
30
1
Intelsat-
Hispasat-
Operator
Source
bus
Satellite
Satellite
Location
34.5°W
24.5°W
24.0°W
22.0°W
Intelsat
907
2003,Ariane
5
Intelsat
905
2002,
June
Ariane
44L
Cosmos
Russia
2379
LM
Nether
A2100AX
lands
Inclined orbit
16
April
2002,Ariane
44L
As of
Remarks
(GMT)
Launch
Coverage
Type
date/rocket
February
44L
Intelsat-
NSS-7
Operator
Source
bus
Satellite
Satellite
Location
27.5°W
15
Intelsat-
18.0°W
15.5°W
Intelsat
603
1990,Commer
cial Titan III
9
Intelsat-
Intelsat
901
June
2001,
Ariane
44L
Inmarsat 3
UK
F2
Telstar 12
Inmarsat
SSL
US
EGNOS PRN
6
September
#120
1996,Proton-K
October
1999,Ariane
44LP
Inclined orbit
As of
Remarks
(GMT)
March
19
15.0°W
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
20.0°W
14
Intelsat-
32
Russia
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Gorizont
Inclined orbit
14.0°W
ExpressA4
12.5°W
11.0°W
8.0°W
Russia
28
Eutelsat
Europe
12 West A
ExpressA3
Eutelsat 8
West A
August
2002,Ariane
5G
24
Russia
formerly Atlantic
Bird 1
2012-03-01
June
2000,Proton-K
25 September
Europe
Eutelsat
2001,Ariane
44P
formerly Atlantic
Bird 2
2012-03-01
2D
e
101
Nilesat
102
Nilesat
103
8
44L
April
1998,Ariane
44P
17
Egypt
August
2000,Ariane
44LP
27
Egypt
February
1998,Ariane
42P
Inclined orbit
As of
Remarks
(GMT)
August
1996,Ariane
28
Egypt
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Franc
Nilesat
7.0°W
Satellite
Satellite
Location
Telecom
201
7.0°W
5.0°W
West A
Eutelsat 5
West A
Israel
Europe
Eutelsat
Europe
Eutelsat
24 September formerly Atlantic
2011
5
Bird 7
July formerly Atlantic
2002, Ariane 5
May
1996,Ariane
4.0°W
27
Israel
As of
2010,Ariane 5
44L
AMOS 2
Remarks
August
16
AMOS 1
(GMT)
date/rocket
Launch
4
Egypt
Eutelsat 7
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Nilesat
December
2003,SoyuzFG/Fregat
Bird 3
2012-03-01
2012-03-01
3.4°W
Meteosat 8
August
2002,Ariane
5G
1.0°W
Intelsat 10-
Intelsat
02
Thor 2
16
June
2004,Proton-M
Norwa
20
May
y
1997, Delta II
0.8°W
Thor 3
Norwa
y
10
June
1998,
Delta
II (7925-9.5)
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
28
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Eastern Hemisphere
2
0.5°E
Meteosa
Europe
t7
ESA
Septembe
Weather
r
satellite
Inclined orbit
1997,Arian
e 44LP
16
3.0°E
Telecom
December
Europe
2A
1991,Arian
e 44L
4.0°E
4.8°E
Eurobird
4
Sirius 4
A2100A
X
Europe
Eutelsat
Sweden
SES Sirius
2
September
1997,Ariane 44LP
Comsat
52 Ku band coveringEu 17
rope
November
200711-18
ndinavia
Luxembo
Astra 1C
urg
on M
12
May
1993,Arian
e 42L
5 October
5.0°E
Sirius 3
Sweden
1998,Arian
e 44L
11
5.2°E
Astra 1A
GE
Luxembo
December
4000
urg
1988,Arian
e 44LP
0.9° inclined
orbit
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
2 Ka band coveringSca 2007,Prot
7.0°E
4F
Eutelsat
W3A
Europe
Military
7 February
communication
2001,Arian Inclined orbit
s
e 44L
15 March
Europe
Eutelsat
2004,Prot
on-M
21
9.0°E
Eurobird
9
Europe
Eutelsat
November
formerly Hot
1996,Atlas
Bird 2
II-A
20
9.5°E
Meteosa
t6
Europe
ESA
Weather
November
satellite
1993,Arian
e 44LP
Inclined orbit
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
6.0°E
Skynet
10.0°E
Eutelsat
W1
Septembe
Europe
Eutelsat
r
2000,Arian
e 44P
12.5°E
Raduga
29
Hot Bird
6
Russia
Inclined orbit
21 August
Europe
Eutelsat
2002,Atlas
V-401
13.0°E
Hot Bird
7A
11 March
Europe
Eutelsat
2006,Arian
e 5 ECA
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
6
8
16.0°E
Eutelsat
W2
Astra 1F
4
Europe
Eutelsat
August
2006,Prot
on
5 October
Europe
Eutelsat
1998,Arian
e 44L
Luxembo
urg
8
April
1996, Prot
on-K
19.2°E
12
Astra 1G
Luxembo
November
urg
1997,Prot
on-K
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Hot Bird
Luxembo
1KR
urg
Arabsat
2A
Luxembo
urg
18
June
1999,Prot
on-K
20
April
2006, Atla
s V (411)
4
May
2007, Aria
ne 5 ECA
9
July
1996, Aria Inclined orbit
ne 44L
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
urg
Astra
Astra 1L
20.0°E
Satellite
Satellite
Location
Astra 1H
Luxembo
21.0°E
AfriStar
October
US
1998,Arian
e 44L
Eutelsat
W6
Europe
Eutelsat
21.5°E
Artemis
23.5°E
Astra 3A
Europe
Luxembo
urg
ESA
EGNOS
#124
PRN
12
July
2001, Aria Inclined orbit.
ne 5G
29 March
2002,Arian
e 44L
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
28
3 F5
UK
Inmarsat
EGNOS
25.0°E
-4 F2
UK
Inmarsat
and
Communicatio
11
EAME
25.0°E
-4A F4
UK
Inmarsat
Communicatio
ns
25.5°E
Eurobird
2
Europe
Eutelsat
and
Aviation
As of
Remarks
(GMT)
June
2005, Zeni
t 3 SL
ns
Inmarsat
date/rocket
1998,Arian
e 44LP
Aviation
Maritime
Launch
4 February
PRN
#126
Maritime
Inmarsat
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
25.0°E
Inmarsat
25
EAME
July
2013,Arian
ne 5ECA
201404-2
201404-2
Astra 2A
HS-
Luxembo
601HP
urg
14
28.2°E
Astra 2B
Luxembo
urg
Septembe
r
2000,Arian
e 5G
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Badr C
Type
26.2°E
Operator
Badr 3
Source
26.0°E
bus
Satellite
Badr 2
Satellite
Location
25.8°E
Astra 2C
June
2001,Prot
urg
on-K
20
Astra 2D
Luxembo
December
urg
2000,Arian
e 5G
28.5°E
Eurobird
Spaceb
1
us 3000
8
Europe
Eutelsat
March
2001,Arian
e 5G
13
30.5°E
Arabsat
2B
Arabsat
November
1996,Arian
e 44L
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
bus
Satellite
Satellite
Location
Source
16
Luxembo
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
1
31.3°E
Astra 1D HS-601
Luxembo
urg
SES
Comsat
24 Ku band
November
2007-
1994,Arian
11-14
e4
19
Astra 1E Hughes
Luxembo
urg
SES
31.5°E
October
1995,Arian
e 42L
Sirius 2
Sweden
27
33.0°E
Eurobird
3
Septembe
Europe
Eutelsat
r
2003,Arian
e 5G
LM-
802
3000
Eutelsat
Sesat 1
25
ITSO
June
1997,Arian
e 44P
17
Europe
Eutelsat
April
2000,Prot
on-K
36.0°E
Eutelsat
W4
38.0°E
Paksat1R
24
Europe
Eutelsat
May
2000, Atla
s IIIA
Space
Pakistan
and
Upper
Atmosphere Research
Commission
11
Aug
2011, Lon
g
3B
March
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Intelsat
40.0°E
Sat 2
Express
AM1
Turksat
1C
13
Greece
May
2003, Atla
s V (401)
Russian
Russia
29
Satellite
October
Communications
2004,Prot
Company(Intersputnik)
on-M
9
Turkey
Turksat
Comsat
16 Ku band
July
1996, Aria
ne 44L
42.0°E
10
Turksat
2A
Turkey
Turksat
Comsat
34 Ku band
January
2001,Arian
e 44P
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
39.0°E
Hellas
Intelsat
ce-1/
Africasat
-1a
49.0°E
53.0°E
Yamal
202
Express
AM22
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Europe
12
Azerspa
46.0°E
Satellite
Satellite
Location
45.0°E
ESA
C-band: Africa, Central
Orbital
STAR2.4
Azerbaija
n
Broadcast and Asia, the Middle East 7 February
Azercosmos
Telecommunic
and Europe, Ku-band: 2013,Arian
ations Satellite
Central
Asia
and e 5 ECA
Europe
Russia
Gazprom
Space
Systems
(subsidiary
of Gazprom)
Russia
Russian
24
November
2003,Prot
on-K
Satellite
Communications
28
December
201409-11
2003,Prot
/Eutelsat
on-K
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
bus
Satellite
Satellite
Location
Source
Company(Intersputnik)
22
56.0°E
Bonum
1
November
Russia
1998,Delta
II
(7925-
9.5)
Maritime
62.6°E
Inmarsat
-5 F1
UK
Inmarsat
8
and
Aviation
Communicatio
December
EAME
ns
64.5°E
Inmarsat
-3 F1
2013,Prot
on M/Briz-
UK
Inmarsat
Aviation
04-2
M
3
Maritime
2014-
and Indian Ocean Region
April
1996, Atla
s IIA|
201404-2
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Communicatio
ns
Television
66°W
Galaxy-
FS-
27
1300
US
Intelsat
broadcasting &
Satellite
Internet Access
66°W
Intelsat
Intelsat
17
25
Septembe
Inclined,
2016-
collocated
04-05
November
ReplacesIntel
2016-
26, 2010
sat 702
04-15
r
1999,Arian
e 44LP
16
68.5°E
Intelsat
FS-
7
1300
Septembe
Europe
ESA
r
1998,Arian
e 44LP
HS-
10
601HP
15
US
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Intelsat
May
2001,Prot
on-K
23
INSAT3C
India
January
ISRO
2002,Arian
e 42L
Originally
74.0°E
12
KALPA
NA-1
India
ISRO
Weather
satellite
Septembe
N/A
r
2002,PSL
V
MetSat-1.
Renamed
in
2003
in 2007-
memory
10-27
ofKalpana
Chawla,
an
astronaut
killed
in
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
theColumbia
accident
20
EDUSA
T
India
ISRO
Educational
6 Ka band and 6 C- Septembe
communication
band
satellite
covering India
transmitters, r
2004,GSL
Also
known 2007-
as GSAT-3
10-27
V
2
INSAT4CR
DTH, VPT and
India
ISRO
DSNG
communication
12 Ku band coveringIn
dia
Septembe
r
2007,GSL
V
75.0°E
ABS 1
Lockheed
Intersputnik
Martin
26
Septembe
r
200710-27
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
1999,Prot
on-K
OriginallyCo
mstar4
forLMGT.
RanamedPar
allax-1
79.0°E
Esafi 1
HS-351
Tongasat
Comsat
in
21
2001
and
February
operated
2007-
1981,Atlas
bySSC
11-10
-Centaur
Parallax.
Purchased
byTongasat a
nd
renamedEsaf
i-1 in 2002
AM2
Russian
Russia
Satellite
29 March
Communications
2005,Prot
Company(Intersputnik)
on-K
6
Yamal
101
Russia
Gazprom
Space
Systems
(subsidiary
of Gazprom)
Septembe
r
1999,Prot
on-K
90.0°E
Yamal
201
Russia
Gazprom
Space
Systems
(subsidiary
of Gazprom)
24
November
2003,Prot
on-K
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
80.0°E
Express
Boeing
T-3
601 HP
Malaysia
MEASAT
Satellite
Systems
Broadcast and South Eastern Europe
Telecommunic
and
ations
Ku-band:
Eastern
Africa
Malaysia,
Indonesia and South
As of
Remarks
11
December
2013-
2006,Prot
10-08
on-M
Asia
91.5°E
C-band:
MEASA
T-3a
96.0°E
(GMT)
Asia,
Australia, Middle East,
MEASA
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
C-band:
Express
AM33
Orbital
STAR-
Malaysia
2.3
MEASAT
Systems
Russian
Russia
Satellite
Satellite
Communications
Company(Intersputnik)
Asia, June
Broadcast and Australia, Middle East 2009, Lan
Telecommunic
and
Eastern
Africa d
Launch
ations
Ku-band:
Malaysia, Zenit
Indonesia
3SLB
28
January
2008,Prot
on-M
-
201310-08
140.0°E
146.0°E
T-5
Loral
FS-
Malaysia
1300 SX
MEASAT
Russia
AM3
Philippin
Agila 2
es
Satellite
Systems
Russian
Express
MEASA
Boeing
T-2
376 HP
Malaysia
Comsat
Malaysia
Satellite
24
June
Company(Intersputnik)
on-K
Comsat,
Space Systems/Loral
and
TV
19 August
Radio Southeast Asia
1997,Long
Broadcasting
March 3B
& and
Satellite
Telecommunic Ku-band:
Hawaii
Broadcast
ations
As of
Remarks
10-08
ne 5G
2005,Prot
Systems
2013-
2005, Aria
Communications
MEASAT
(GMT)
August
C-band: Asia Pacific
148.0°E
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
119.5°E
MEASA
West
Malaysia/Indonesia
(Sumatra
Taiwan,
&
Java),
Eastern
13
November
1996,Arian
e 44L
inclined orbit
201310-08
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Australia, Vietnam and
the
Philippines
(switchable)
Optus
B3
HS-601
Australia
Optus/Commonwealth
Bank
27 August
Comsat
1994,Long
March 2E
200710-28
152.0°E
Optus
D2
5 October
STAR-2
Australia
Optus
Comsat
2007,Arian
e 5GS
4
166.0°E
Intelsat
FS-
8
1300
US
November
1998,Prot
on-K
200710-28
178.0°E
Inmarsat
-3 F3
UK
Inmarsat
and
Aviation
Communicatio
ns
As of
Remarks
(GMT)
date/rocket
Launch
Coverage
Type
Operator
Source
bus
Satellite
Satellite
Location
Maritime
18
Pacific Ocean Region
December
2014-
1996,Atlas
04-2
IIA
4. Military satellite
A military satellite is an artificial satellite used for a military purpose. Intelligence gathering,
navigation and military communications are the most common missions of a military satellite. As
of 2013, there are 950 satellites of all types in Earth orbit. It is not possible to identify the exact
number of these that are military satellites partly due to secrecy and partly due to dual purpose
missions such as GPS satellites that serve both civilian and military purposes.
Reconnaissance and Surveillance
Reconnaissance and surveillance involve the observation of Earth for various purposes. Dedicated
reconnaissance satellites, like the United States's Improved CRYSTAL and the Russian Terilen,
take photographs of targets on the ground and relay them to receiving stations in nearly real time.
These satellites, however, cannot take continuous images like a television camera. Instead, they
take a black-and-white photograph of a target every few seconds. Because they are in low orbits
and are constantly moving, they can photograph a target for only a little over a minute before they
move out of range. The best American satellites, which are similar in appearance to the Hubble
Space Telescope, can see objects about the size of a softball from hundreds of miles up but they
cannot read license plates. The Russians also occasionally use a system that takes photographs on
film and then returns the film to Earth for processing. This provides them with higher-quality
photos. The United States abandoned this technology in the 1980s after developing superior
electronic imaging technology.
Other nations, such as France and Japan, operate or plan on operating reconnaissance satellites
that can see images on the ground about one to three feet in length. From the late 1970s until the
mid-1990s, China had a film-based system, which is no longer operational. India, Israel, and Brazil
also operate satellites capable of making visual observations of the ground. Some private companies
operate commercial imagery satellites and sell images on the World Wide Web. These satellites are
much less capable than the larger military satellites but their products have improved significantly
and are in demand.
Other surveillance satellites, such as the American DSP and Space-Based Infrared System (SBIRS,
pronounced "sibirs") and the Russian Oko (or "eye"), are equipped with infrared telescopes and
scan the ground for the heat produced by a missile's exhaust. They can be used to warn of missile
attack and can predict the targets of missiles fired hundreds or thousands of miles away. There are
also satellites that look at the ground in different wavelengths to peer through camouflage, try to
determine what objects are made of, and analyze smokestack emissions.
Navigation and Meteorology
Navigation satellites are also vital to military forces. Sailors have used the stars to navigate for
centuries. Beginning in the early 1960s, the U.S. Navy developed a satellite system to help it
navigate at sea. This was particularly important for ballistic missile submarines that stayed
submerged for most of their patrols and could only occasionally raise an antenna above the waves
to determine their position.
In the 1980s the U.S. Air Force started operating the Global Positioning System (GPS), which
allowed anyone equipped with a receiver to locate his or her position on Earth to within about
thirty feet or less. GPS uses a constellation of twenty-four satellites that circle Earth every twelve
hours. From any point on Earth, there are usually three or four GPS satellites above the horizon at
any one time. A handheld receiver detects radio emissions from these satellites.
Commercial receivers are available in sporting goods stores and in many new cars. Using a special
civilian GPS signal, they provide less precise location information than the military receivers but
still allow a user to navigate accurately. Civilian users can locate their position on Earth to an
accuracy of about thirty feet. Russia operates a system similar to GPS, but virtually every military
on the planet uses the civilian GPS signal.
Accurate weather information is critical to military operations. The United States and Russia
operate meteorology satellites for military use. However, since the end of the Cold War, separate
military and civilian meteorology satellites have been viewed as an unnecessary expense, and the
military systems have gradually been merged with their similar civilian counterparts.
Antisatellite Defense ("Star Wars")
Antisatellite (ASAT) and missile defense (Strategic Defense Initiative [SDI] or "Star Wars")
satellites are not currently part of any nation's arsenal. ASAT weapons are difficult to develop and
operate and they have limited usefulness. It is extremely precarious to use a satellite to shoot down
ballistic missiles. In the future, satellites may be used to intercept missiles, but it is unlikely that
this will happen for a long time.
During the Cold War, both superpowers studied the possibility of placing nuclear weapons in
orbit, but neither country did so. A bomb in orbit will spend most of its time nowhere near the
target it needs to hit, unlike a missile on the ground, which will always be in range of its target. In
addition, controlling a system of orbiting bombs would be difficult.
Military Satellite Development
Russia launched the Sputnik 1 in 1957 and within four months the United States had also
launched their first satellite. The first spy satellites were deployed by the U.S. Air Force as part of
their Corona program, launched in 1959. This program, operated jointly by the CIA and Air Force
until 1972, was used to perform photographic surveillance of China and the Soviet Union.
In roughly the same time period, the Soviet Union launched its Zenit program. Between 1961 and
1964, the Soviets deployed a number of military reconnaissance satellites.
Before digital imaging capabilities, spy satellites had to send their photographs in canisters. A
canister containing a film roll was ejected with a parachute, and a pilot intercepted the package
before it reached the ground. Current technology uses encrypted radio links to download digital
images.
Today the U.S. Air Force operates the Navigation Signal Timing and Ranging Global Positioning
System (NAVSTAR) GPS network. This satellite navigation network tracks military forces across
the globe, whether on land or in the air or sea. It is comprised of 25 satellites, though at present 4
are not operational. GLONASS is a similar, Russian-operated network navigation system.
5. Satellite navigation
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geospatial positioning. Satellite navigation is a leading-edge technology which allows anyone with a
receiver to determine their position very accurately at any time by picking up signals from a
constellation of several satellites. Currently, the United States Global Positioning System (GPS)
and the Russian GLONASS system are the only operational Satellite navigation systems. Europe
has begun the development of a third independent global system, known as ‘Galileo’. Mainly satellite navigation system has three parts: 1. The Space segment 2. The Control segment 3. The User segment
All these parts operate together to provide accurate three‐dimensional positioning, timing and velocity data to users worldwide. The Space Segment The GPS system constellation has 24 satellites in six 55° orbital planes, with four satellites in each plane, with room for spares. The orbit period of each satellite is approximately 12 hours at an altitude of 20,183 kilometers. With this constellation, a user receiver has at least six satellites in view from any point on earth. Other systems use satellites in different orbits and orbital periods. The satellite broadcast signal contains data which identifies the satellite and provides the positioning, timing, ranging data, satellite status and corrected orbit parameters of the satellite. GPS satellites transmit on two frequencies; one centered at 1575.42 MHz, known as L1 and the other at 1227.60 MHz, known as L2. The L1 carrier is modulated by the C/A code (Coarse/Acquisition) and the P code (Precision). P code is encrypted for military and other authorized users. The L2 carrier is modulated only with the P code. Similar signals exist for Galileo and GLONASS, although both systems differ in the way signals are delivered. New L2C and L5 signals are being added to the system as new satellites are launched. The Control Segment The GPS control segment consists of a master control station, five base stations and three data up‐
loading stations in locations round the globe. Other configurations are possible for other satellite navigation systems. The base stations track and monitor the satellites via their broadcast signals. These signals are passed to the master control station where orbital parameters and timing corrections are computed. The resulting corrections are transmitted back to the satellites via the data up‐loading stations. The User Segment User receivers, can be referred to as the User Segment, and consist of equipment which track and receive the satellite signals. User receivers must be capable of simultaneously processing the signals from a minimum of four satellites to obtain accurate position, velocity and timing measurements. However accuracy and reliability is enhanced as the number of visible satellites increases.
Applications
1. Air traffic navigation and control and their related accuracy and integrity; enhancement infrastructure; 2. Management and tracking of ship and land vehicle fleets; 3. Rental and personal car navigation systems; 4. Automation of container location and tracking to increase the efficiency of ports; 5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Navigation systems for remotely piloted air, land and water vehicles; Road and rail traffic monitoring; Dispatch and monitoring of emergency services; Automated car and truck guidance systems; Automated guidance of agricultural equipment for efficiency improvements in crop spraying and harvesting Recreational guidance for hikers, boaters, cyclists and explorers; Aerial, seismic, and land surveying; Large structure monitoring (such as dams, bridges, buildings, etc); Accurate timing systems for communications and commerce; and Earthquake and tsunami detection and warning systems.
Classification 
GNSS‐1 is the first generation system and is the combination of existing satellite navigation
systems (GPS and GLONASS), with Satellite Based Augmentation Systems (SBAS) or
Ground Based Augmentation Systems (GBAS). In the United States, the satellite based
component is the Wide Area Augmentation System (WAAS), in Europe it is the European
Geostationary Navigation Overlay Service (EGNOS), and in Japan it is the MultiFunctional Satellite Augmentation System (MSAS). Ground based augmentation is
provided by systems like the Local Area Augmentation System (LAAS). 
GNSS-2 is the second generation of systems that independently provides a full civilian
satellite navigation system, exemplified by the European Galileo positioning system. These
systems will provide the accuracy and integrity monitoring necessary for civil navigation;
including aircraft. This system consists of L1 and L2 frequencies for civil use and L5 for
system integrity. Development is also in progress to provide GPS with civil use L2 and L5
frequencies, making it a GNSS-2 system.

Core Satellite navigation systems, currently GPS (United States), GLONASS (Russian
Federation), Galileo (European Union) and Compass (China).

Global Satellite Based Augmentation Systems (SBAS) such as Omnistar and Star Fire.

Regional SBAS including WAAS (US), EGNOS (EU), MSAS (Japan) and GAGAN
(India).

Regional Satellite Navigation Systems such as China's Beidou, India's NAVIC, and Japan's
proposed QZSS.

Continental scale Ground Based Augmentation Systems (GBAS) for example the
Australian GRAS and the US Department of Transportation National Differential GPS
(DGPS) service.

Regional scale GBAS such as CORS networks.

Local GBAS typified by a single GPS reference station operating Real Time Kinematic
(RTK) corrections.
Global satellite navigation systems
Operational
1. GPS: The United States' Global Positioning System (GPS) consists of up to 32 medium Earth
orbit satellites in six different orbital planes, with the exact number of satellites varying as older
satellites are retired and replaced. Operational since 1978 and globally available since 1994, GPS
is currently the world's most utilized satellite navigation system.
2. GLONASS: GLONASS is a space-based satellite navigation system that provides a civilian
radio navigation satellite service and is also used by the Russian Aerospace Defence Forces. The
full orbital constellation of 24 GLONASS satellites enables full global coverage.
In Development
1. Galileo: The European Union and European Space Agency agreed in March 2002 to introduce
their own alternative to GPS, called the Galileo positioning system. The original year to become
operational was 2014. The first experimental satellite was launched on 28 December 2005. Galileo
is expected to be compatible with the modernized GPS system. The receivers will be able to
combine the signals from both Galileo and GPS satellites to greatly increase the accuracy. Galileo
is now not expected to be in full service until 2020 at the earliest and at a substantially higher cost.
The main modulation used in Galileo Open Service signal is the Composite Binary Offset Carrier
(CBOC) modulation.
2. BeiDou: China has indicated they plan to complete the entire second generation Beidou
Navigation Satellite System (BDS or BeiDou-2, formerly known as COMPASS), by expanding
current regional (Asia-Pacific) service into global coverage by 2020. The BeiDou-2 system is
proposed to consist of 30 MEO satellites and five geostationary satellites. A 16-satellite regional
version (covering Asia and Pacific area) was completed by December 2012.
Regional satellite navigation systems
1. BeiDou-1: Chinese regional (Asia-Pacific, 16 satellites) network to be expanded into the
whole global system which consists of all 35 satellites by 2020.
2. NAVIC: The NAVIC or NAVigation with Indian Constellation is an autonomous
regional satellite navigation system developed by Indian Space Research Organisation (ISRO)
which would be under the total control of Indian government. The government approved the
project in May 2006, with the intention of the system completed and implemented on 28 April
2016. It will consist of a constellation of 7 navigational satellites. 3 of the satellites will be placed
in the Geostationary orbit (GEO) and the remaining 4 in the Geosynchronous orbit (GSO) to
have a larger signal footprint and lower number of satellites to map the region. It is intended to
provide an all-weather absolute position accuracy of better than 7.6 meters throughout India and
within a region extending approximately 1,500 km around it. A goal of complete Indian control
has been stated, with the space segment, ground segment and user receivers all being built in India.
All seven satellites, IRNSS-1A, IRNSS-1B, IRNSS-1C, IRNSS-1D, IRNSS-1E, IRNSS-1F, and
IRNSS-1G, of the proposed constellation were precisely launched on 1 July 2013, 4 April 2014,
16 October 2014, 28 March 2015, 20 January 2016, 10 March 2016 and 28 April 2016
respectively from Satish Dhawan Space Centre. The system is expected to be fully operational by
August 2016.
3. QZSS: The Quasi-Zenith Satellite System (QZSS), is a proposed three-satellite regional time
transfer system and enhancement for GPS covering Japan. The first demonstration satellite was
launched in September 2010.
Comparison of systems
System
GPS
GLONASS
BeiDou
Galileo
NAVIC
Owner
United
States
Russian
Federation
China
European
Union
India
Coding
CDMA
FDMA
CDMA
CDMA
CDMA
Orbital altitude
20,180 km 19,130
km 21,150
km 23,222 km 36,000
km
(12,540 mi) (11,890 mi)
(13,140 mi)
(14,429 mi) (22,000 mi)
Period
11.97
(11
58 min)
Revolutions
persidereal day
2
Number
satellites
Frequency
Status
h
11.26 h (11 h 12.63 h (12 h 14.08
h
h
16 min)
38 min)
(14 h 5 min)
17/8
17/9
28 (at least 24
by
design)
including:
24 operational
32 (at least
2 under check
of
24
by
by the satellite
design)
prime
contractor
2 in flight tests
phase
Around
1.57542 GH 1.602
z (L1 signal) (SP)
1.2276 GHz Around
(L2 signal)
1.246
(SP)
Operational
4
in-orbit
validation
5
satellites + 8
geostationary full
orbit
(GEO) operation
Total : 7
satellites,
capable
30
medium satellites in
In Orbit : 7
Earth
orbit orbit
(MEO)
22
satellites
operational
satellites
budgeted
1.561098 GH
z
(B1)
GHz 1.589742 GH
z
(B1-2)
1.20714 GHz
GHz (B2)
1.26852 GHz
(B3)
Operational
17/10
22 satellites
operational,
40 additional
satellites
2016-2020
1.164–
1.215 GHz
(E5a
and
E5b)
1.260–
1.300 GHz
(E6)
1.559–
1.592 GHz
(E2-L1-E11)
L5-band
1164.45–
1188.45 MHz
Sband 2483.52500 MHz)
8 satellites
operational,
22
Operational
additional
satellites
2016-2020
6. Tracking and data relay satellite
A tracking and data relay satellite (TDRS) is a type of communications satellite that forms part of
the Tracking and Data Relay Satellite System (TDRSS) used by NASA and other United States
government agencies for communications to and from independent "User Platforms" such as
satellites, balloons, aircraft, the International Space Station, and remote bases like the AmundsenScott South Pole Station. . This system was designed to replace an existing worldwide network of
ground stations that had supported all of NASA's manned flight missions and unmanned satellites
in low-Earth orbits. The primary system design goal was to increase the amount of time that these
spacecraft were in communication with the ground and improve the amount of data that could be
transferred. These TDRSS satellites are all designed and built to be launched to and function in
geosynchronous orbit, 35,786 km (22,236 mi) above the surface of the Earth.
The first seven TDRSS satellites were built by the TRW corporation. The three later versions have
been manufactured by the Boeing corporation's Satellite Systems division. Ten satellites have been
launched; however, one was destroyed in the Challenger disaster. TDRS-1 was decommissioned
in October 2009.[1] TDRS-4 was decommissioned in December 2011. Seven TDRSS satellites
are still in service.[2] All of the TDRSS satellites have been managed by NASA's Goddard Space
Flight Center.[3] The contract for TDRS versions L & K was awarded to Boeing on December
20, 2007. On November 30, 2011, NASA announced the decision to order an additional thirdgeneration TDRS satellite, TDRS M.
Operations and Design
The first tracking and data relay satellite was launched in 1983 on the Space Shuttle Challenger's
first flight, STS-6. The Boeing-built Inertial Upper Stage that was to take the satellite from
Challenger's orbit to its ultimate geosynchronous orbit suffered a failure that caused it not to
deliver the TDRS to the correct orbit. As a result, it was necessary to command the satellite to use
its onboard rocket thrusters to move it into its correct orbit. This expenditure of fuel reduced its
capability to remain in a geostationary orbit; by late 1997 the orbit had changed to the point that
the satellite was able to see the South Pole, and an uplink/downlink station was installed at
Amundsen–Scott South Pole Station in January 1998; TDRS-1 was an important communication
uplink for Antarctic research until 2009.
The second tracking and data relay satellite was destroyed along with Challenger shortly after
launch during the STS-51-L mission in January 1986. The next five TRW-built TDRSS satellites
were successfully launched on other Space Shuttles. Three follow-up Boeing-built satellites were
launched by Atlas rockets in 2000 and 2002.
The communications systems of the TDRSS satellites were designed to support multiple missions
at the same time. Each satellite has S band, Ku band (1st Gen only), and Ka band (2nd gen only)
electronic communication systems hardware that operate at different carrier frequencies and also
support various data-rates. The newer Boeing satellites are able to support more communications
than the older TRW-built satellites.
List of different TDRS satellites
Satellites
Designation
Laun
ch
Operati
onal
Launc
h
(UTC)
Rocket
Launch
Site
Longit
ude
Statu
s
Retire
ment
Remarks
27
June
2010
IUS
malfuncti
oned,
raised
orbit
using
maneuve
ring
thrusters.
End
of
life
October
2009
First generation
TDR
S-A
4 April
1983
TDRS-1
18:30:
00
Space
Shuttle Challe Kennedy
nger/IUS
LC-39A
(STS-6)
TDR
S-B
N/A
28
Januar
y 1986
16:38:
00
Space
Shuttle Challe Kennedy
nger/IUS
LC-39B
(STS-51-L)
TDR
S-C
29
Septe
mber
TDRS-3
1988
15:37:
00
Space
Shuttle Discov Kennedy
ery/IUS
LC-39B
(STS-26R)
In
storag
Decem
ber
2011
TDR
S-D
13
March
TDRS-4 1989
14:57:
00
Space
Shuttle Discov Kennedy
ery/IUS
LC-39B
(STS-29R)
Retire
d
April/M
ay
2012
41°W,
62°W,
171°W
Retire
d
N/A
28
Januar
Destro
y 1986
yed
16:39:1
3
Launch
failure
Shuttle
disintegrat
ed during
ascent
TDR
S-E
2
August
TDRS-5 1991
15:02:
00
Space
Shuttle Atlantis Kennedy
/IUS
LC-39A
(STS-43)
TDR
S-F
13
Januar
TDRS-6 y 1993
13:59:
30
Space
Shuttle Endea Kennedy
vour/IUS
LC-39B
(STS-54)
Active
,
TDR
S-G
13 July
1995
TDRS-7
13:41:
55
Space
Shuttle Discov Kennedy
ery/IUS
LC-39B
(STS-70)
Active
,
In
storag
e
as
of
2009
as
of
2009
Replaced
TDRS-B
Second generation
TDR
S-H
30
June
TDRS-8
2000
12:56
Atlas IIA
Canavera
lSLC-36A
TDR
S-I
8
March
TDRS-9
2002
22:59
Atlas IIA
Canavera
lSLC-36A
Active
5
Decem
ber
Atlas IIA
2002
02:42
Canavera
lSLC-36A
Active
TDR
S-J
TDRS10
171°W
Active
Third generation
TDR
S-K
TDR
S-L
TDR
S-M
TDRS11
31
Januar
y 2013 Atlas V 401
01:48:
00
Canavera
lSLC-41
TDRS12
24
Januar
y 2014 Atlas V 401
02:33:
00
Canavera
lSLC-41
Planne
d
Atlas VEELV
Canavera
l
171°W
Active
USD$35
0 million
cost, paid
to Boeing
under a
firm-fixed
price
(FFP)
contract.
Active
USD$35
0 million
cost, FFP
contract.
USD$28
9 million
firmfixedprice
contract
option
with
Boeing;
option
exercise
d
in
Novemb
er 2011,
ahead of
expiry on
30 Nov
2012.
TDR
S-N
Planne
d
EELV
Canavera
l
Option
TDRSS Milestones
Jul 1981 White Sands Ground Terminal (WSGT) completed. Apr 1983 TDRS‐1 launched aboard the Space Shuttle Challenger. Aug 1983 First TDRS customer support occurs with Landsat‐4 mission. First Space Shuttle (STS‐8) test communications support occurs through TDRS‐1. Jan 1986 TDRS‐2 destroyed during Space Shuttle Challenger launch. Sep 1988 TDRS‐3 launched aboard Space Shuttle Discovery. Nov 1988 Dual TDRS‐1 and TDRS‐3 support begins. Mar 1989 TDRS‐4 launched aboard Space Shuttle Discovery. Aug 1991 TDRS‐5 launched aboard Space Shuttle Atlantis. Jan 1993 TDRS‐6 launched aboard Space Shuttle Endeavour. Dec 1993 Compton Gamma Ray Observatory on‐board tape recorder failure (3/92) prompts closure of TDRS zone of exclusion to minimize science data loss. Temporary TDRSS capability implemented in Canberra, Australia. Apr 1994 Second Ground Terminal completed. Mar 1995 White Sands Ground Terminal decommissioned; upgrades begin. Jul 1995 TDRS‐7 (last TDRS built by TRW) launched aboard Space Shuttle Discovery. Feb 1996 White Sands Ground Terminal upgrades complete. Sep 1996 Guam Remote Ground Terminal implementation Phase II efforts begin. Jun 1998 Guam Remote Ground Terminal completed. Jul 1998 Guam Remote Ground Terminal declared operational; closes TDRS “zone of exclusion.” Jan 1999 South Pole TDRSS relay implemented, allowing National Science Foundation to receive/transmit data from South Pole. TDRSS service also assists in resolving medical emergency at the Pole. Jun 2000 TDRS‐H launched aboard an Atlas IIA rocket. Oct 2001 NASA accepts TDRS‐H; renaming it TDRS‐8.
TDRS-A was the first of TDRSS multiple satellite tracking system. The system is a concept
utilizing communication satellite technology that improves and economizes the satellite tracking
and telemetry operations. The base three geosynchronous satellites (one a standby) track and
receive data from satellites for relay to a ground station. The two primary active satellites are
separated in orbit by at least 130 degrees longitude.
One system is used for tracking satellites with apogees below 2000 km (the great majority of
satellites), and the other for those with higher apogees. Use of operating frequencies near 2150
(plus or minus 150) MHz and near 14.3 (plus or minus 0.9) GHz were the initial plan.
TDRSS was originally intended to support satellites with apogees below 12,000 km. Spacecraft in
the TDRSS require only one communications system, since ground-based telemetry stations will
be compatible with TDRSS equipment.
7. Weather satellite
The weather satellite is a type of satellite that is primarily used to monitor the weather and climate
of the Earth. Satellites can be polar orbiting, covering the entire Earth asynchronously, or
geostationary, hovering over the same spot on the equator.
Meteorological satellites see more than clouds and cloud systems. City lights, fires, effects of
pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents,
energy flows, etc., and other types of environmental information are collected using weather
satellites. Weather satellite images helped in monitoring the volcanic ash cloud from Mount St.
Helens and activity from other volcanoes such as Mount Etna. Smoke from fires in the western
United States such as Colorado and Utah have also been monitored.
History of meteorological satellites
Sputnik was the first satellite in the world. After 3 years flight, the first meteorological satellite
TIROS-1 was launched by the United States of America in April 1960. For 6 years after that, 10
satellites of the TIROS series were launched and used for conducting various observations and
experiments. The TIROS series were low elevation orbit satellites. In 1966, the first geostationary
meteorological satellite ATS-1 was launched by the United States and it was confirmed that the
satellite observation was effective for meteorological monitoring.
The success of meteorological satellite observation intensified the trend toward using this new
technology to develop meteorology and improve weather forecasting.
In 1963, the World Meteorological Organization (WMO) drafted the WWW (World Weather
Watch) Programme and started a meteorological satellite observation network plan covering the
globe. In response to this plan, various countries launched their meteorological satellites and these
established an observation network covering the globe with 5 geostationary satellites and 2 polar
orbiting satellites (NOAA and METEOR series) at the beginning of the 1980s After that, Russia
and China launched geostationary satellites.
Japan launched Himawari (GMS hereafter) I in 1977. Five satellites of the GMS series were
launched up to date and GMS-5 is in operation. As a successor to the GMS series satellites, Multifunctional Transport Satellite (MTSAT hereafter) is to be launched.
History of meteorological satellites
Year
Item
Country
1960
1966
1970
1975
1977
First meteorological satellite TIROS I launched
First geostationary meteorological satellite launched
NOAA series launched
GOES launched
GMS and METEOSAT launched 1982 INSAT launched
1982
INSAT launched
1994
1997
GOMS launched
FY-II launched
USA
USA
USA
USA
Japan, Europe
India
Russia
China
Observation
The advantages of the meteorological observation using meteorological satellites include its
capability of observing the whole earth uniformly with a fine spatial density. Therefore, it is
effective for monitoring short-time atmospheric phenomena including the cloud motion and drift
of typhoons and lows. It is also used for monitoring of climate changes based on the accumulation
of the global data over a long period.
Observation is typically made via different 'channels' of the Electromagnetic spectrum, in
particular, the Visible and Infrared portions.
Some of these channels include


Visible and Near Infrared: 0.6 μm – 1.6 μm – For recording cloud cover during the day
Infrared: 3.9 μm – 7.3 μm (Water Vapor), 8.7 μm, – 13.4 μm (Thermal imaging)
Visible spectrum
Visible-light images from weather satellites during local daylight hours are easy to interpret even
by the average person; clouds, cloud systems such as fronts and tropical storms, lakes, forests,
mountains, snow ice, fires, and pollution such as smoke, smog, dust and haze are readily apparent.
Even wind can be determined by cloud patterns, alignments and movement from successive
photos.
Infrared spectrum
The thermal or infrared images recorded by sensors called scanning radiometers enable a trained
analyst to determine cloud heights and types, to calculate land and surface water temperatures, and
to locate ocean surface features. Infrared satellite imagery can be used effectively for tropical
cyclones with a visible eye pattern, using the Dvorak technique, where the difference between the
temperature of the warm eye and the surrounding cold cloud tops can be used to determine its
intensity (colder cloud tops generally indicate a more intense storm) Infrared pictures depict ocean
eddies or vortices and map currents such as the Gulf Stream which are valuable to the shipping
industry. Fishermen and farmers are interested in knowing land and water temperatures to protect
their crops against frost or increase their catch from the sea. Even El Niño phenomena can be
spotted. Using color-digitized techniques, the gray shaded thermal images can be converted to
color for easier identification of desired information.
Uses
Snowfield monitoring, especially in the Sierra Nevada, can be helpful to the hydrologist keeping
track of available snowpack for runoff vital to the watersheds of the western United States. This
information is gleaned from existing satellites of all agencies of the U.S. government (in addition
to local, on-the-ground measurements). Ice floes, packs and bergs can also be located and tracked
from weather space craft.
Even pollution whether it is nature-made or man-made can be pinpointed. The visual and infrared
photos show effects of pollution from their respective areas over the entire earth. Aircraft and rocket
pollution, as well as condensation trails, can also be spotted. The ocean current and low level wind
information gleaned from the space photos can help predict oceanic oil spill coverage and
movement. Almost every summer, sand and dust from the Sahara Desert in Africa drifts across the
equatorial regions of the Atlantic Ocean. GOES-EAST photos enable meteorologists to observe,
track and forecast this sand cloud. In addition to reducing visibilities and causing respiratory
problems, sand clouds suppress hurricane formation by modifying the solar radiation balance of
the tropics. Other dust storms in Asia and mainland China are common and easy to spot and
monitor, with recent examples of dust moving across the Pacific Ocean and reaching North
America.
In remote areas of the world with few local observers, fires could rage out of control for days or
even weeks and consume millions of acres before authorities are alerted. Weather satellites can be
a tremendous asset in such situations. Nighttime photos also show the burn-off in gas and oil fields.
Atmospheric temperature and moisture profiles have been taken by weather satellites since 1969.
Specific Satellites
List of satellites which have provided data on the Earth's magnetosphere are listed below.
Satellite
Launch
Date
Inclination of orb
Lifetime
ital
plane
to
(days)
Earth'sequator
Range Sensitivi
(γ)
ty
Distance
RE
Sputnik 3
March
15, 1958
65°
30
<60,00
5%
0
<1.3
Explorer 3
March
1958
Pioneer 1
October
11, 1958
Earth impact
1
<1000
3.7-7.0
Lunik 1
January
2, 1959
Solar orbit
1
<6,000 200γ
1%
3-6
Explorer 6
August 7,
47°
1959
61
<20,00
3%
0
2-7.5
Lunik 2
Septemb
er
12, Lunar impact
1959
1.4°
<1,500 50γ
3-6
Vanguard 3
Septemb
er
18, 33°
1959
85
10,000
4γ
60,000
<1.8
Pioneer 5
March
11, 1960
Solar orbit
50°
<1,000 0.05-5γ
5-9
Explorer 10
March
25, 1961
33°
2.2
305,000
3γ
1.8-7
Explorer 12
August
16, 1961
33°
112
±500
10γ
4-13.5
Alouette 1
Septemb
er
29, 80°
1962
Still
60,000 0.3%
operating
1.17
Explorer 14
October
3, 1962
300
5-16.5
Denpa (REXS)
August
19, 1972
Kyokko
A)
(EXOS- February
4, 1978
International
Cometary
Explorer
August
12, 1978
33°
±250
5γ
Septemb
Jikiken (EXOS-B) er
16,
1978
Dynamics
Explorer
August 3,
1981
GEOTAIL
July 24,
1992
Still
operating
WIND
Novemb
er
1,
1994
Still
operating
Ørsted
February
23, 1999
96.4798°
Still
operating
IMAGE
March
25, 2000
90°
Decemb
er, 2005
THEMIS
February
17, 2001
16°
Still
operating
Double
mission
0.2-7.2
Decemb
er
29,
Star
2003 &
July 25,
2004
July 16,
Cluster
II
90° (then changed
2000 and
Still
(spacecraft) miss
during
mission
August 9,
operating
ion
operation)
2000
4-20
Polar
TWINS
June, 28
2006 and
63°
March,
13, 2008
Still
operating
0.2-6.5
August
30, 2012
Still
operating
MMS
March
13, 2015
Still
operating
ERG
2016
Van Allen Probes
Ion
Release
Module
Charge
Composition
Explorer
Space exploration technology
1. Aerobot
An aerobot is an aerial robot, usually used in the context of an unmanned space probe or unmanned
aerial vehicle.
While work has been done since the 1960s on robot "rovers" to explore the Moon and other worlds
in the Solar system, such machines have limitations. They tend to be expensive and have limited
range, and due to the communications time lags over interplanetary distances, they have to be
smart enough to navigate without disabling themselves.
For planets with atmospheres of any substance, however, there is an alternative: an autonomous
flying robot, or "aerobot". Most aerobot concepts are based on aerostats, primarily balloons, but
occasionally airships. Flying above obstructions in the winds, a balloon could explore large regions
of a planet in great detail for relatively low cost. Airplanes for planetary exploration have also been
proposed.
Basics of balloons
While the notion of sending a balloon to another planet sounds strange at first, balloons have a
number of advantages for planetary exploration. They can be made light in weight and are
potentially relatively inexpensive. They can cover a great deal of ground, and their view from a
height gives them the ability to examine wide swathes of terrain with far more detail than would
be available from an orbiting satellite. For exploratory missions, their relative lack of directional
control is not a major obstacle as there is generally no need to direct them to a specific location.
Balloon designs for possible planetary missions have involved a few unusual concepts. One is the
solar, or infrared (IR) Montgolfiere. This is a hot-air balloon where the envelope is made from a
material that traps heat from sunlight, or from heat radiated from a planetary surface. Black is the
best color for absorbing heat, but other factors are involved and the material may not necessarily
be black. Solar Montgolfieres have several advantages for planetary exploration, as they can be easier
to deploy than a light gas balloon, do not necessarily require a tank of light gas for inflation, and
are relatively forgiving of small leaks. They do have the disadvantage that they are only aloft during
daylight hours.
The other is a "reversible fluid" balloon. This type of balloon consists of an envelope connected to
a reservoir, with the reservoir containing a fluid that is easily vaporized. The balloon can be made
to rise by vaporizing the fluid into gas, and can be made to sink by condensing the gas back into
fluid. There are a number of different ways of implementing this scheme, but the physical principle
is the same in all cases. A balloon designed for planetary exploration will carry a small gondola
containing an instrument payload. The gondola will also carry power, control, and
communications subsystems. Due to weight and power supply constraints, the communications
subsystem will generally be small and low power, and interplanetary communications will be
performed through an orbiting planetary probe acting as a relay. A solar Montgolfiere will sink at
night, and will have a guide rope attached to the bottom of the gondola that will curl up on the
ground and anchor the balloon during the darkness hours. The guide rope will be made of low
friction materials to keep it from catching or tangling on ground features.
Alternatively, a balloon may carry a thicker instrumented "snake" in place of the gondola and
guiderope, combining the functions of the two. This is a convenient scheme for making direct
surface measurements.
A balloon could also be anchored to stay in one place to make atmospheric observations. Such a
static balloon is known as an "aerostat".
One of the trickier aspects of planetary balloon operations is inserting them into operation.
Typically, the balloon enters the planetary atmosphere in an "aeroshell", a heat shield in the shape
of a flattened cone. After atmospheric entry, a parachute will extract the balloon assembly from the
aeroshell, which falls away. The balloon assembly then deploys and inflates.
Once operational, the aerobot will be largely on its own and will have to conduct its mission
autonomously, accepting only general commands over its long link to Earth. The aerobot will have
to navigate in three dimensions, acquire and store science data, perform flight control by varying
its altitude, and possibly make landings at specific sites to provide close-up investigation.
The Venus Vega balloons
The first, and so far only, planetary balloon mission was performed by the Space Research Institute
of Soviet Academy of Sciences in cooperation with the French space agency CNES in 1985. A
small balloon, similar in appearance to terrestrial weather balloons, was carried on each of the two
Soviet Vega Venus probes, launched in 1984.
The first balloon was inserted into the atmosphere of Venus on 11 June 1985, followed by the
second balloon on 15 June 1985. The first balloon failed after only 56 minutes, but the second
operated for a little under two Earth days until its batteries ran down. The Venus Vega balloons
were the idea of Jacques Blamont, chief scientist for CNES and the father of planetary balloon
exploration. He energetically promoted the concept and enlisted international support for the small
project. The scientific results of the Venus VEGA probes were modest. More importantly, the
clever and simple experiment demonstrated the validity of using balloons for planetary exploration.
The Mars aerobot effort
After the success of the Venus VEGA balloons, Blamont focused on a more ambitious balloon
mission to Mars, to be carried on a Soviet space probe.
The atmospheric pressure on Mars is about 150 times less than that of Earth. In such a thin
atmosphere, a balloon with a volume of 5,000 to 10,000 cubic meters (178,500 to 357,000 cubic
feet) could carry a payload of 20 kilograms (44 pounds), while a balloon with a volume of 100,000
cubic meters (3,600,000 cubic feet) could carry 200 kilograms (440 pounds).
The French had already conducted extensive experiments with solar Montgolfieres, performing
over 30 flights from the late 1970s into the early 1990s. The Montgolfieres flew at an altitude of
35 kilometers, where the atmosphere was as thin and cold as it would be on Mars, and one spent
69 days aloft, circling the Earth twice.
Early concepts for the Mars balloon featured a "dual balloon" system, with a sealed hydrogen or
helium-filled balloon tethered to a solar Montgolfiere. The light-gas balloon was designed to keep
the Montgolfiere off the ground at night. During the day, the Sun would heat up the Montgolfiere,
causing the balloon assembly to rise. The group decided on a cylindrical sealed helium balloon
made of aluminized PET film, and with a volume of 5,500 cubic meters (196,000 cubic feet). The
balloon would rise when heated during the day and sink as it cooled at night. Total mass of the
balloon assembly was 65 kilograms (143 pounds), with a 15 kilogram (33 pound) gondola and a
13.5 kilogram (30 pound) instrumented guiderope. The balloon was expected to operate for ten
days. Unfortunately, although considerable development work was performed on the balloon and
its subsystems, Russian financial difficulties pushed the Mars probe out from 1992, then to 1994,
and then to 1996. The Mars balloon was dropped from the project due to cost.
JPL aerobot experiments
The Jet Propulsion Laboratory (JPL) of the US National Aeronautics and Space Administration
(NASA) had become interested in the idea of planetary aerobots, and in fact a team under Jim
Cutts of JPL had been working on concepts for planetary aerobots for several years, as well as
performing experiments to validate aerobot technology.
The first such experiments focused on a series of reversible-fluid balloons, under the project name
ALICE, for "Altitude Control Experiment". The first such balloon, ALICE 1, flew in 1993, with
other flights through ALICE 8 in 1997.
Related work included the characterization of materials for a Venus balloon envelope, and two
balloon flights in 1996 to test instrument payloads under the name BARBE, for "Balloon Assisted
Radiation Budget Equipment".
By 1996, JPL was working on a full-fledged aerobot experiment named PAT, for "Planetary
Aerobot Testbed", which was intended to demonstrate a complete planetary aerobot through
flights into Earth's atmosphere. PAT concepts envisioned a reversible-fluid balloon with a 10kilogram payload that would include navigation and camera systems, and eventually would operate
under autonomous control. The project turned out to be too ambitious, and was cancelled in 1997.
JPL continued to work on a more focused, low-cost experiments to lead to a Mars aerobot, under
the name MABVAP, for "Mars Aerobot Validation Program". MABVAP experiments included
drops of balloon systems from hot-air balloons and helicopters to validate the tricky deployment
phase of a planetary aerobot mission, and development of envelopes for superpressure balloons
with materials and structures suited to a long-duration Mars mission.
JPL also provided a set of atmospheric and navigation sensors for the Solo Spirit round-the-world
manned balloon flights, both to support the balloon missions and to validate technologies for
planetary aerobots.
While these tests and experiments were going on, JPL performed a number of speculative studies
for planetary aerobot missions to Mars, Venus, Saturn's moon Titan, and the outer planets.
 Mars
JPL's MABVAP technology experiments were intended to lead to an actual Mars aerobot mission,
named MABTEX, for "Mars Aerobot Technology Experiment". As its name implies, MABTEX
was primarily intended to be an operational technology experiment as a precursor to a more
ambitious efforts. MABTEX was envisioned as a small superpressure balloon, carried to Mars on a
"microprobe" weighing no more than 40 kilograms (88 lb). Once inserted, the operational balloon
would have a total mass of no more than 10 kilograms (22 lb) and would remain operational for a
week. The small gondola would have navigational and control electronics, along with a stereo
imaging system, as well as a spectrometer and magnetometer. Plans envisioned a follow-on to
MABTEX as a much more sophisticated aerobot named MGA, for "Mars Geoscience Aerobot".
Design concepts for MGA envisioned a superpressure balloon system very much like that of
MABTEX, but much larger. MGA would carry a payload ten times larger than that of MABTEX,
and would remain aloft for up to three months, circling Mars more than 25 times and covering
over 500,000 kilometres (310,000 mi). The payload would include sophisticated equipment, such
as an ultrahigh resolution stereo imager, along with oblique imaging capabilities; a radar sounder
to search for subsurface water; an infrared spectroscopy system to search for important minerals; a
magnetometer; and weather and atmospheric instruments. MABTEX might be followed in turn
by a small solar-powered blimp named MASEPA, for "Mars Solar Electric Propelled Aerobot".
 Venus
JPL has also pursued similar studies on Venus aerobots. A Venus Aerobot Technology Experiment
(VEBTEX) has been considered as a technology validation experiment, but the focus appears to
have been more on full operational missions. One mission concept, the Venus Aerobot Multisonde
(VAMS), envisions an aerobot operating at altitudes above 50 kilometres (31 mi) that would drop
surface probes, or "sondes", onto specific surface targets. The balloon would then relay information
from the sondes directly to Earth, and would also collect planetary magnetic field data and other
information. VAMS would require no fundamentally new technology, and may be appropriate for
a NASA low-cost Discovery planetary science mission. Significant work has been performed on a
more ambitious concept, the Venus Geoscience Aerobot (VGA). Designs for the VGA envision a
relatively large reversible-fluid balloon, filled with helium and water, that could descend to the
surface of Venus to sample surface sites, and then rise again to high altitudes and cool off.
Developing an aerobot that can withstand the high pressures and temperatures (up to 480 degrees
Celsius, or almost 900 degrees Fahrenheit) on the surface of Venus, as well as passage through
sulfuric acid clouds, will require new technologies. As of 2002, VGA was not expected to be ready
until late in the following decade. Prototype balloon envelopes have been fabricated from
polybenzoxazole, a polymer that exhibits high strength, resistance to heat, and low leakage for light
gases. A gold coating is applied to allow the polymer film to resist corrosion from acid clouds.
Work has also been done on a VGA gondola weighing about 30 kilograms (66 lb). In this design,
most instruments are contained in a spherical pressure vessel with an outer shell of titanium and
an inner shell of stainless steel. The vessel contains a solid-state camera and other instruments, as
well as communications and flight control systems. The vessel is designed to tolerate pressures of
up to a hundred atmospheres and maintain internal temperatures below 30 °C (86 °F) even on the
surface of Venus. The vessel is set at the bottom of a hexagonal "basket" of solar panels that in turn
provide tether connections to the balloon system above, and is surrounded by a ring of pipes acting
as a heat exchanger. An S-band communications antenna is mounted on the rim of the basket, and
a radar antenna for surface studies extends out of the vessel on a mast.
 Titan
Titan, the largest moon of Saturn, is an attractive target for aerobot exploration, as it has a nitrogen
atmosphere five times as dense as that of Earth's that contains a smog of organic photochemicals,
hiding the moon's surface from view by visual sensors. An aerobot would be able to penetrate this
haze to study the moon's mysterious surface and search for complex organic molecules. NASA has
outlined a number of different aerobot mission concepts for Titan, under the general name of
Titan Biologic Explorer.
One concept, known as the Titan Aerobot Multisite mission, involves a reversible-fluid balloon
filled with argon that could descend from high altitude to the surface of the moon, perform
measurements, and then rise again to high altitude to perform measurements and move to a
different site. Another concept, the Titan Aerobot Singlesite mission, would use a superpressure
balloon that would select a single site, vent much of its gas, and then survey that site in detail.
An ingenious variation on this scheme, the Titan Aerover, combines aerobot and rover. This
vehicle features a triangular frame that connects three balloons, each about two meters (6.6 ft) in
diameter. After entry into Titan's atmosphere, the aerover would float until it found an interesting
site, then vent helium to descend to the surface. The three balloons would then serve as floats or
wheels as necessary. JPL has built a simple prototype that looks three beachballs on a tubular frame.
No matter what form the Titan Biologic Explorer mission takes, the system would likely require
an atomic-powered radioisotope thermoelectric generator module for power. Solar power would
not be possible at Saturn's distance and under Titan's smog, and batteries would not give adequate
mission endurance. The aerobot would also carry a miniaturized chemical lab to search for
complicated organic chemicals.
Outside of JPL, other mission studies of Titan aerobot concepts have included studies of airships
by MIT and NASA Glenn, and a proposed Titan airplane proposed by NASA Ames.
 Jupiter
Finally, aerobots might be used to explore the atmosphere of Jupiter and possibly the other gaseous
outer planets. As the atmospheres of these planets are largely composed of hydrogen, and since
there is no lighter gas than hydrogen, such an aerobot would have to be a Montgolfiere. As sunlight
is weak at such distances, the aerobot would obtain most of its heating from infrared energy
radiated by the planet below. A Jupiter aerobot might operate at altitudes where the air pressure
ranges from one to ten atmospheres, occasionally dropping lower for detailed studies. It would
make atmospheric measurements and return imagery and remote sensing of weather phenomena,
such as Jupiter's Great Red Spot. A Jupiter aerobot might also drop sondes deep into the
atmosphere and relay their data back to an orbiter until the sondes are destroyed by temperature
and pressure.
2. Lunar rover
A lunar rover or Moon rover is a space exploration vehicle (rover) designed to move across the
surface of the Moon. Some rovers have been designed to transport members of a human spaceflight
crew, such as the U.S. Apollo program's Lunar Roving Vehicle; others have been partially or fully
autonomous robots, such as Soviet Lunokhods and Chinese Yutu. As of 2013, three countries have
had rovers on the Moon: the Soviet Union, the United States and China.
 Past missions
1. Lunokhod 1
Lunokhod 1 was the first polycrystalline-panel-powered of two unmanned lunar rovers landed on
the moon by the Soviet Union as part of its Lunokhod program after previous unsuccessful attempt
of launch probe with Lunokhod 0 (No.201) in 1969. The panels were designed by Electronic and
Communication Engineer Bryan Mapúa. The spacecraft which carried Lunokhod 1 was named
Luna 17. The spacecraft soft-landed on the Moon in the Sea of Rains on November 1970.
Lunokhod was the first roving remote-controlled robot to land on another celestial body. Having
worked for 11 months, Lunokhod 1 held the durability record for space rovers for more than 30
years, until a new record was set by the Mars Exploration Rovers.
2. Lunokhod 2
Lunokhod 2 was the second and a monocrystalline-panel-powered of two unmanned lunar rovers
landed on the Moon by the Soviet Union as part of the Lunokhod program. The Luna 21
spacecraft landed on the Moon and deployed the second Soviet lunar rover Lunokhod 2 in January
1973. The objectives of the mission were to collect images of the lunar surface, examine ambient
light levels to determine the feasibility of astronomical observations from the Moon, perform laser
ranging experiments, observe solar X-rays, measure local magnetic fields, and study the soil
mechanics of the lunar surface material. Lunokhod 2 intended to be followed by Lunokhod 3
(No.205) in 1977 but mission was cancelled.
3. Apollo Lunar Roving Vehicle
The Lunar Roving Vehicle (LRV) was a battery-powered four-wheeled rover used on the Moon
during the last three missions of the American Apollo program (15, 16, and 17) during 1971 and
1972. The LRV could carry one or two astronauts, their equipment, and lunar samples.
4. Yutu
Yutu is a Chinese lunar rover which launched on 1 December 2013 and landed on 14 December
2013 as part of the Chang'e 3 mission. It is China's first lunar rover, part of the second phase of
the Chinese Lunar Exploration Program undertaken by China National Space Administration
(CNSA). The lunar rover is called Yutu, or Jade Rabbit, a name selected in an online poll. The
rover encountered operational difficulties after the first 14-day lunar night, and was unable to move
after the end of the second lunar night, yet it is still gathering some useful data.
The Yutu rover might be the world's first true hibernating robot on the moon.
 Planned missions
1. Barcelona Moon Team rover
Barcelona Moon Team is a team participating in the Google Lunar X Prize, with a planned launch
date for the mission in 2015.
2. Astrobotic Technology rover
Astrobotic Technology, a private company based in Pittsburgh, Pennsylvania, United States, plans
to send a rover to the Moon in late 2017, as part of the Google Lunar X Prize.
3. Chang'e 4 rover
Chinese mission with a planned launch date before 2020.
4. Chandrayaan-2 rover
The Chandrayaan-2 mission is the first lunar rover mission by India, consisting of a lunar orbiter
and a lunar lander. The rover weighing 50 kg, will have six wheels and will be running on solar
power. It will land near one of the poles and will operate for a year, roving up to 150 km at a
maximum speed of 360 m/h. The proposed launch date of the mission is 2017.
5. SELENE-2 rover
Planned Japanese robotic mission to the Moon will include an orbiter, a lander and a rover. It is
expected to be launched in 2017.
 Proposed missions
1. ATHLETE
NASA's plans for future moon missions call for rovers that have a far longer range than the Apollo
rovers. The All-Terrain Hex-Legged Extra-Terrestrial Explorer (ATHLETE) is a six-legged robotic
lunar rover test-bed under development by the Jet Propulsion Laboratory (JPL). ATHLETE is a
testbed for systems and is designed for use on the Moon. The system is in development along with
NASA's Johnson and Ames Centers, Stanford University and Boeing. ATHLETE is designed, for
maximum efficiency, to be able to both roll and walk over a wide range of terrains.
2. Luna-Grunt rover
Luna-Grunt rover (or Luna-28) is a proposed Russian lunar rover (lunokhod).
3. Scarab
Scarab is a new generation lunar rover designed to assist astronauts, take rock and mineral samples,
and explore the lunar surface. It is being developed by the Robotics Institute of Carnegie Mellon
University, supported by NASA.
4. Space Exploration Vehicle
The SEV is a proposed successor to the original Lunar Roving Vehicle from the Apollo missions.
It combines a living module, as it has a pressurized cabin containing a small bathroom and space
for 2 astronauts (4 in case of emergency), and a small truck.
3. Mars rover
A Mars rover is an automated motor vehicle that propels itself across the surface of the planet Mars
upon arrival. Rovers have several advantages over stationary landers: they examine more territory,
and they can be directed to interesting features, they can place themselves in sunny positions to
weather winter months, and they can advance the knowledge of how to perform very remote
robotic vehicle control. There have been four successful robotically operated Mars rovers. The Jet
Propulsion Laboratory managed the Mars Pathfinder mission and its now inactive Sojourner rover.
It currently manages the Mars Exploration Rover mission's active Opportunity rover and inactive
Spirit, and, as part of the Mars Science Laboratory mission, the Curiosity rover. On January 24,
2014, NASA reported that current studies on the planet Mars by the Curiosity and Opportunity
rovers will now be searching for evidence of ancient life, including a biosphere based on
autotrophic, chemotrophic, and/or chemolithoautotrophic microorganisms, as well as ancient
water, including fluvio-lacustrine environments (plains related to ancient rivers or lakes) that may
have been habitable. The search for evidence of habitability, taphonomy (related to fossils), and
organic carbon on the planet Mars is now a primary NASA objective.
Synopsis
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Mars 2, Prop-M rover, 1971, Mars 2 landing failed taking Prop-M with it. The Mars
2 and 3 spacecraft from the USSR had identical 4.5 kg Prop-M rovers. They were to move
on skis while connected to the landers with cables.
Mars 3, Prop-M rover, 1971, lost when Mars 3 lander stopped communicating about 20
seconds after landing.
Sojourner rover, Mars Pathfinder, landed successfully on July 4, 1997. Communications
were lost on September 27, 1997.
Beagle 2, Planetary Undersurface Tool, lost with Beagle 2 on deployment from Mars
Express in 2003. A compressed spring mechanism was designed to allow movement across the
surface at a rate of 1 cm per 5 seconds and to burrow into the ground and collect a subsurface
sample in a cavity in its tip.
Spirit (MER-A), Mars Exploration Rover, launched on June 10, 2003 at 13:58:47 EDT
and landed successfully on January 4, 2004. Nearly 6 years after the original mission limit,
Spirit had covered a total distance of 7.73 km (4.80 mi) but its wheels became trapped in
sand. Around January 26, 2010, NASA conceded defeat in its efforts to free the rover and
stated that it would now function as a stationary science platform. The last communication
received from the rover was on March 22, 2010, and NASA ceased attempts to re-establish
communication on May 25, 2011.
Opportunity (MER-B), Mars Exploration Rover, launched on July 7, 2003 at 23:18:15
EDT and landed successfully on January 25, 2004. Opportunity surpassed the previous record
for longevity of a surface mission to Mars as of May 20, 2010 and surpassed the previous record
for distance traveled off-Earth as of July 28, 2014 by covering a total distance of 40.25 km
(25.01 mi). Opportunity is still operational and mobile as of October 9, 2016.
Curiosity, Mars Science Laboratory (MSL), by NASA, was launched November 26, 2011
at 10:02 EST and landed in the Aeolis Palus plain near Aeolis Mons (informally "Mount
Sharp") in Gale Crater on August 6, 2012, 05:31 UTC. Curiosity Rover is still operational as
of October 9, 2016.
Concepts
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ExoMars, by the ESA. Planned Mars launch 2018.The rover will use stained glass to
prevent UV
from changing image colors, allowing for true color images of the surface
of Mars.
Chinese Mars Rover, has been planned for a pre-2020 launch, as part of a sample-return
mission.
MESR (Mars Exploration Science Rover), REX (Robot EXplorer), and MRPTA (MicroRover Platform with Tooling Arm) have a target destination of Mars, planned by the
Canadian Space Agency (CSA).
Mars 2020, a NASA rover based on the current rover Curiosity and planned to launch in
2020.
2020 Chinese Mars Mission, would include an orbiter, lander and small rover.
Goals
The four science goals of NASA's long-term Mars Exploration Program are:
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Determine whether life ever arose on Mars
Characterize the climate of Mars
Characterize the geology of Mars
Prepare for human exploration of Mars
Space flight technology
1. Atmospheric entry
Atmospheric entry is the movement of an object from outer space into and through the gases of
an atmosphere of a planet, dwarf planet or natural satellite. There are two main types of
atmospheric entry: uncontrolled entry, such as the entry of astronomical objects, space debris or
bolides; and controlled entry (or reentry) of a spacecraft capable of being navigated or following a
predetermined course. Technologies and procedures allowing the controlled atmospheric entry,
descent and landing of spacecraft are collectively abbreviated as EDL. Atmospheric drag and
aerodynamic heating can cause atmospheric breakup capable of completely disintegrating smaller
objects. These forces may cause objects with lower compressive strength to explode.
For Earth, atmospheric entry occurs above the Kármán line at an altitude of more than 100 km
(62 mi.) above the surface, while at Venus atmospheric entry occurs at 250 km (155 mi.) and at
Mars atmospheric entry at about 80 km (50 mi.). Uncontrolled, objects accelerate through the
atmosphere at extreme velocities under the influence of Earth's gravity. Most controlled objects
enter at hypersonic speeds due to their suborbital (e.g., intercontinental ballistic missile reentry
vehicles), orbital (e.g., the Space Shuttle), or unbounded (e.g., meteors) trajectories. Various
advanced technologies have been developed to enable atmospheric reentry and flight at extreme
velocities. An alternative low velocity method of controlled atmospheric entry is buoyancy which
is suitable for planetary entry where thick atmospheres, strong gravity or both factors complicate
high-velocity hyperbolic entry, such as the atmospheres of Venus, Titan and the gas giants.
History
The concept of the ablative heat shield was described as early as 1920 by Robert Goddard: "In the
case of meteors, which enter the atmosphere with speeds as high as 30 miles per second (48 km/s),
the interior of the meteors remains cold, and the erosion is due, to a large extent, to chipping or
cracking of the suddenly heated surface. For this reason, if the outer surface of the apparatus were
to consist of layers of a very infusible hard substance with layers of a poor heat conductor between,
the surface would not be eroded to any considerable extent, especially as the velocity of the
apparatus would not be nearly so great as that of the average meteor. Practical development of
reentry systems began as the range and reentry velocity of ballistic missiles increased. For early
short-range missiles, like the V-2, stabilization and aerodynamic stress were important issues (many
V-2s broke apart during reentry), but heating was not a serious problem. Medium-range missiles
like the Soviet R-5, with a 1200 km range, required ceramic composite heat shielding on separable
reentry vehicles (it was no longer possible for the entire rocket structure to survive reentry). The
first ICBMs, with ranges of 8000 to 12,000 km, were only possible with the development of
modern ablative heat shields and blunt-shaped vehicles. In the USA, this technology was pioneered
by H. Julian Allen at Ames Research Center.
Entry vehicle shapes
1. Sphere or spherical section
The simplest axisymmetric shape is the sphere or spherical section. This can either be a complete
sphere or a spherical section fore body with a converging conical after body. The aerodynamics of
a sphere or spherical section is easy to model analytically using Newtonian impact theory. Likewise,
the spherical section's heat flux can be accurately modeled with the Fay-Riddell equation. The
static stability of a spherical section is assured if the vehicle's center of mass is upstream from the
center of curvature (dynamic stability is more problematic). Pure spheres have no lift. However,
by flying at an angle of attack, a spherical section has modest aerodynamic lift thus providing some
cross-range capability and widening its entry corridor. In the late 1950s and early 1960s, highspeed computers were not yet available and computational fluid dynamics was still embryonic.
Because the spherical section was amenable to closed-form analysis, that geometry became the
default for conservative design. Consequently, manned capsules of that era were based upon the
spherical section.
Pure spherical entry vehicles were used in the early Soviet Vostok and Voskhod and in Soviet Mars
and Venera descent vehicles. The Apollo Command/Service Module used a spherical section
forebody heat shield with a converging conical afterbody. It flew a lifting entry with a hypersonic
trim angle of attack of −27° (0° is blunt-end first) to yield an average L/D (lift-to-drag ratio) of
0.368. This angle of attack was achieved by precisely offsetting the vehicle's center of mass from
its axis of symmetry. Other examples of the spherical section geometry in manned capsules are
Soyuz/Zond, Gemini and Mercury. Even these small amounts of lift allow trajectories that have
very significant effects on peak g-force (reducing g-force from 8-9g for a purely ballistic (slowed
only by drag) trajectory to 4-5g) as well as greatly reducing the peak reentry heat.
2. Sphere-cone
The sphere-cone is a spherical section with a frustum or blunted cone attached. The sphere-cone's
dynamic stability is typically better than that of a spherical section. With a sufficiently small halfangle and properly placed center of mass, a sphere-cone can provide aerodynamic stability from
Keplerian entry to surface impact. (The "half-angle" is the angle between the cone's axis of
rotational symmetry and its outer surface, and thus half the angle made by the cone's surface edges.)
The original American sphere-cone aeroshell was the Mk-2 RV (reentry vehicle), which was
developed in 1955 by the General Electric Corp. The Mk-2's design was derived from blunt-body
theory and used a radiatively cooled thermal protection system (TPS) based upon a metallic heat
shield (the different TPS types are later described in this article). The Mk-2 had significant defects
as a weapon delivery system, i.e., it loitered too long in the upper atmosphere due to its lower
ballistic coefficient and also trailed a stream of vaporized metal making it very visible to radar.
These defects made the Mk-2 overly susceptible to anti-ballistic missile (ABM) systems.
Consequently, an alternative sphere-cone RV to the Mk-2 was developed by General Electric. This
new RV was the Mk-6 which used a non-metallic ablative TPS (nylon phenolic). This new TPS
was so effective as a reentry heat shield that significantly reduced bluntness was possible. However,
the Mk-6 was a huge RV with an entry mass of 3360 kg, a length of 3.1 meters and a half-angle of
12.5°. Subsequent advances in nuclear weapon and ablative TPS design allowed RVs to become
significantly smaller with a further reduced bluntness ratio compared to the Mk-6. Since the 1960s,
the sphere-cone has become the preferred geometry for modern ICBM RVs with typical half-angles
being between 10° to 11°. Reconnaissance satellite RVs (recovery vehicles) also used a sphere-cone
shape and were the first American example of a non-munition entry vehicle (Discoverer-I,
launched on 28 February 1959). The sphere-cone was later used for space exploration missions to
other celestial bodies or for return from open space; e.g., Stardust probe. Unlike with military RVs,
the advantage of the blunt body's lower TPS mass remained with space exploration entry vehicles
like the Galileo Probe with a half angle of 45° or the Viking aeroshell with a half angle of 70°.
Space exploration sphere-cone entry vehicles have landed on the surface or entered the atmospheres
of Mars, Venus, Jupiter and Titan.
3. Biconic
The biconic is a sphere-cone with an additional frustum attached. The biconic offers a significantly
improved L/D ratio. A biconic designed for Mars aerocapture typically has an L/D of
approximately 1.0 compared to an L/D of 0.368 for the Apollo-CM. The higher L/D makes a
biconic shape better suited for transporting people to Mars due to the lower peak deceleration.
Arguably, the most significant biconic ever flown was the Advanced Maneuverable Reentry Vehicle
(AMaRV). Four AMaRVs were made by the McDonnell-Douglas Corp. and represented a
significant leap in RV sophistication. Three of the AMaRVs were launched by Minuteman-1
ICBMs on 20 December 1979, 8 October 1980 and 4 October 1981. AMaRV had an entry mass
of approximately 470 kg, a nose radius of 2.34 cm, a forward frustum half-angle of 10.4°, an interfrustum radius of 14.6 cm, aft frustum half angle of 6°, and an axial length of 2.079 meters. No
accurate diagram or picture of AMaRV has ever appeared in the open literature. However, a
schematic sketch of an AMaRV-like vehicle along with trajectory plots showing hairpin turns has
been published. AMaRV's attitude was controlled through a split body flap along with two yaw
flaps mounted on the vehicle's sides. Hydraulic actuation was used for controlling the flaps.
AMaRV was guided by a fully autonomous navigation system designed for evading anti-ballistic
missile (ABM) interception. The McDonnell Douglas DC-X (also a biconic) was essentially a
scaled-up version of AMaRV. AMaRV and the DC-X also served as the basis for an unsuccessful
proposal for what eventually became the Lockheed Martin X-33.
4. Non-axisymmetric shapes
Non-axisymmetric shapes have been used for manned entry vehicles. One example is the winged
orbit vehicle that uses a delta wing for maneuvering during descent much like a conventional glider.
This approach has been used by the American Space Shuttle and the Soviet Buran. The lifting
body is another entry vehicle geometry and was used with the X-23 PRIME (Precision Recovery
Including Maneuvering Entry) vehicle. The FIRST (Fabrication of Inflatable Re-entry Structures
for Test) system was an Aerojet proposal for an inflated-spar Rogallo wing made up from Inconel
wire cloth impregnated with silicone rubber and silicon carbide dust. FIRST was proposed in both
one-man and six man versions, used for emergency escape and reentry of stranded space station
crews, and was based on an earlier unmanned test program that resulted in a partially successful
reentry flight from space (the launcher nose cone fairing hung up on the material, dragging it too
low and fast for the thermal protection system (TPS), but otherwise it appears the concept would
have worked; even with the fairing dragging it, the test article flew stably on reentry until burnthrough).
The proposed MOOSE system would have used a one-man inflatable ballistic capsule as an
emergency astronaut entry vehicle. This concept was carried further by the Douglas Paracone
project. While these concepts were unusual, the inflated shape on reentry was in fact axisymmetric.
Thermal protection systems
Multiple approaches for the thermal protection of spacecraft are in use, among them ablative heat
shields, passive cooling and active cooling of spacecraft surfaces.
Ablative
The ablative heat shield functions by lifting the hot shock layer gas away from the heat shield's
outer wall (creating a cooler boundary layer). The boundary layer comes from blowing of gaseous
reaction products from the heat shield material and provides protection against all forms of heat
flux. The overall process of reducing the heat flux experienced by the heat shield's outer wall by
way of a boundary layer is called blockage. Ablation occurs at two levels in an ablative TPS: the
outer surface of the TPS material chars, melts, and sublimes, while the bulk of the TPS material
undergoes pyrolysis and expels product gases. The gas produced by pyrolysis is what drives blowing
and causes blockage of convective and catalytic heat flux. Pyrolysis can be measured in real time
using thermogravimetric analysis, so that the ablative performance can be evaluated. Ablation can
also provide blockage against radiative heat flux by introducing carbon into the shock layer thus
making it optically opaque. Radiative heat flux blockage was the primary thermal protection
mechanism of the Galileo Probe TPS material (carbon phenolic). Carbon phenolic was originally
developed as a rocket nozzle throat material (used in the Space Shuttle Solid Rocket Booster) and
for re-entry vehicle nose tips. Early research on ablation technology in the USA was centered at
NASA's Ames Research Center located at Moffett Field, California. Ames Research Center was
ideal, since it had numerous wind tunnels capable of generating varying wind velocities. Initial
experiments typically mounted a mock-up of the ablative material to be analyzed within a
hypersonic wind tunnel. Testing of ablative materials occurs at the Ames Arc Jet Complex. Many
spacecraft thermal protection systems have been tested in this facility, including the Apollo, space
shuttle, and Orion heat shield materials.
The thermal conductivity of a particular TPS material is usually proportional to the material's
density. Carbon phenolic is a very effective ablative material, but also has high density which is
undesirable. If the heat flux experienced by an entry vehicle is insufficient to cause pyrolysis then
the TPS material's conductivity could allow heat flux conduction into the TPS bondline material
thus leading to TPS failure. Consequently, for entry trajectories causing lower heat flux, carbon
phenolic is sometimes inappropriate and lower density TPS materials such as the following
examples can be better design choices:
I.
SLA-561V
SLA in SLA-561V stands for super light-weight ablator. SLA-561V is a proprietary ablative made
by Lockheed Martin that has been used as the primary TPS material on all of the 70° sphere-cone
entry vehicles sent by NASA to Mars other than the Mars Science Laboratory (MSL). SLA-561V
begins significant ablation at a heat flux of approximately 110 W/cm², but will fail for heat fluxes
greater than 300 W/cm². The MSL aeroshell TPS is currently designed to withstand a peak heat
flux of 234 W/cm². The peak heat flux experienced by the Viking-1 aeroshell which landed on
Mars was 21 W/cm². For Viking-1, the TPS acted as a charred thermal insulator and never
experienced significant ablation. Viking-1 was the first Mars lander and based upon a very
conservative design. The Viking aeroshell had a base diameter of 3.54 meters (the largest used on
Mars until Mars Science Laboratory). SLA-561V is applied by packing the ablative material into a
honeycomb core that is pre-bonded to the aeroshell's structure thus enabling construction of a
large heat shield.
II.
Phenolic impregnated carbon ablator
Phenolic impregnated carbon ablator (PICA), a carbon fiber preform impregnated in phenolic
resin, is a modern TPS material and has the advantages of low density (much lighter than carbon
phenolic) coupled with efficient ablative ability at high heat flux. It is a good choice for ablative
applications such as high-peak-heating conditions found on sample-return missions or lunarreturn missions. PICA's thermal conductivity is lower than other high-heat-flux ablative materials,
such as conventional carbon phenolics. PICA was patented by NASA Ames Research Center in the
1990s and was the primary TPS material for the Stardust aeroshell. The Stardust sample-return
capsule was the fastest man-made object ever to reenter Earth's atmosphere (12.4 km/s (28,000
mph) at 135 km altitude). This was faster than the Apollo mission capsules and 70% faster than
the Shuttle. PICA was critical for the viability of the Stardust mission, which returned to Earth in
2006. Stardust's heat shield (0.81 m base diameter) was made of one monolithic piece sized to
withstand a nominal peak heating rate of 1.2 kW/cm2. A PICA heat shield was also used for the
Mars Science Laboratory entry into the Martian atmosphere.
III.
PICA-X
An improved and easier to produce version called PICA-X was developed by SpaceX in 2006-2010
for the Dragon space capsule. The first re-entry test of a PICA-X heat shield was on the Dragon
C1 mission on 8 December 2010. The PICA-X heat shield was designed, developed and fully
qualified by a small team of only a dozen engineers and technicians in less than four years. PICAX is ten times less expensive to manufacture than the NASA PICA heat shield material.
The Dragon 1 spacecraft initially used PICA-X version 1 and was later equipped with version 2.
The Dragon V2 spacecraft uses PICA-X version 3. SpaceX has indicated that each new version of
PICA-X primarily improves upon heat shielding capacity rather than the manufacturing cost.
IV.
SIRCA
Silicone-impregnated reusable ceramic ablator (SIRCA) was also developed at NASA Ames
Research Center and was used on the Backshell Interface Plate (BIP) of the Mars Pathfinder and
Mars Exploration Rover (MER) aeroshells. The BIP was at the attachment points between the
aeroshell's backshell (also called the afterbody or aft cover) and the cruise ring (also called the cruise
stage). SIRCA was also the primary TPS material for the unsuccessful Deep Space 2 (DS/2) Mars
impactor probes with their 0.35 m base diameter aeroshells. SIRCA is a monolithic, insulating
material that can provide thermal protection through ablation. It is the only TPS material that can
be machined to custom shapes and then applied directly to the spacecraft. There is no postprocessing, heat treating, or additional coatings required (unlike Space Shuttle tiles). Since SIRCA
can be machined to precise shapes, it can be applied as tiles, leading edge sections, full nose caps,
or in any number of custom shapes or sizes. As of 1996, SIRCA had been demonstrated in backshell
interface applications, but not yet as a forebody TPS material.
V.
AVCOAT
It is a NASA-specified ablative heat shield, a glass-filled epoxy-novolac system.
NASA originally used it for the Apollo capsule and then utilized the material for its next-generation
beyond low Earth-orbit Orion spacecraft. The Avcoat to be used on Orion has been reformulated
to meet environmental legislation that has been passed since the end of Apollo.
Passively-cooled
In some early ballistic missile RVs (e.g., the Mk-2 and the suborbital Mercury spacecraft),
radiatively-cooled TPS were used to initially absorb heat flux during the heat pulse, and, then, after
the heat pulse, radiate and convect the stored heat back into the atmosphere. However, the earlier
version of this technique required a considerable quantity of metal TPS (e.g., titanium, beryllium,
copper, etc.). Modern designers prefer to avoid this added mass by using ablative and thermal-soak
TPS instead. Radiatively-cooled TPS can still be found on modern entry vehicles, but reinforced
carbon-carbon (RCC) (also called carbon-carbon) is normally used instead of metal. RCC was the
TPS material on the Space Shuttle's nose cone and wing leading edges, and was also proposed as
the leading-edge material for the X-33. Carbon is the most refractory material known, with a oneatmosphere sublimation temperature of 3825 °C for graphite. This high temperature made carbon
an obvious choice as a radiatively cooled TPS material. Disadvantages of RCC are that it is
currently very expensive to manufacture, and lacks impact resistance. Some high-velocity aircraft,
such as the SR-71 Blackbird and Concorde, deal with heating similar to that experienced by
spacecraft, but at much lower intensity, and for hours at a time. Studies of the SR-71's titanium
skin revealed that the metal structure was restored to its original strength through annealing due
to aerodynamic heating. In the case of the Concorde, the aluminium nose was permitted to reach
a maximum operating temperature of 127 °C (approximately 180 °C warmer than the, normally
sub-zero, ambient air); the metallurgical implications (loss of temper) that would be associated
with a higher peak temperature were the most significant factors determining the top speed of the
aircraft.
A radiatively-cooled TPS for an entry vehicle is often called a hot-metal TPS. Early TPS designs
for the Space Shuttle called for a hot-metal TPS based upon a nickel superalloy (dubbed René 41)
and titanium shingles. This Shuttle TPS concept was rejected, because it was believed a silica-tilebased TPS would involve lower development and manufacturing costs. A nickel superalloy-shingle
TPS was again proposed for the unsuccessful X-33 single-stage-to-orbit (SSTO) prototype.
Recently, newer radiatively-cooled TPS materials have been developed that could be superior to
RCC. Referred to by their prototype vehicle Slender Hypervelocity Aerothermodynamic Research
Probe (SHARP), these TPS materials have been based upon substances such as zirconium diboride
and hafnium diboride. SHARP TPS have suggested performance improvements allowing for
sustained Mach 7 flight at sea level, Mach 11 flight at 100,000 ft (30,000 m) altitudes, and
significant improvements for vehicles designed for continuous hypersonic flight. SHARP TPS
materials enable sharp leading edges and nose cones to greatly reduce drag for airbreathing
combined-cycle-propelled spaceplanes and lifting bodies. SHARP materials have exhibited
effective TPS characteristics from zero to more than 2,000 °C, with melting points over 3,500 °C.
They are structurally stronger than RCC, and, thus, do not require structural reinforcement with
materials such as Inconel. SHARP materials are extremely efficient at reradiating absorbed heat,
thus eliminating the need for additional TPS behind and between the SHARP materials and
conventional vehicle structure. NASA initially funded a multi-phase R&D program through the
University of Montana in 2001 to test SHARP materials on test vehicles.
Actively cooled
Various advanced reusable spacecraft and hypersonic aircraft designs have been proposed to employ
heat shields made from temperature-resistant metal alloys that incorporated a refrigerant or
cryogenic fuel circulating through them. Such a TPS concept was proposed for the X-30 National
Aerospace Plane (NASP). The NASP was supposed to have been a scramjet powered hypersonic
aircraft, but failed in development.
In the early 1960s various TPS systems were proposed to use water or other cooling liquid sprayed
into the shock layer, or passed through channels in the heat shield. Advantages included the
possibility of more all-metal designs which would be cheaper to develop, be more rugged, and
eliminate the need for classified technology. The disadvantages are increased weight and
complexity, and lower reliability. The concept has never been flown, but a similar technology did
undergo extensive ground testing.
Feathered reentry
In 2004, aircraft designer Burt Rutan demonstrated the feasibility of a shape-changing airfoil for
reentry with the suborbital SpaceShipOne. The wings on this craft rotate upward into the feather
configuration that provides a shuttlecock effect. Thus SpaceShipOne achieves much more
aerodynamic drag on reentry while not experiencing significant thermal loads.
The configuration increases drag, as the craft is now less streamlined and results in more
atmospheric gas particles hitting the spacecraft at higher altitudes than otherwise. The aircraft thus
slows down more in higher atmospheric layers which is the key to efficient reentry. Secondly the
aircraft will automatically orient itself in this state to a high drag attitude.
On 4 May 2011, the first test on the SpaceShipTwo of the feathering mechanism was made during
a glideflight after release from the White Knight Two.
The feathered reentry was first described by Dean Chapman of NACA in 1958.[41] In the section
of his report on Composite Entry, Chapman described a solution to the problem using a high-drag
device:
It may be desirable to combine lifting and nonlifting entry in order to achieve some advantages...
For landing maneuverability it obviously is advantageous to employ a lifting vehicle. The total heat
absorbed by a lifting vehicle, however, is much higher than for a nonlifting vehicle... Nonlifting
vehicles can more easily be constructed... by employing, for example, a large, light drag device...
The larger the device, the smaller is the heating rate.
Nonlifting vehicles with shuttlecock stability are advantageous also from the viewpoint of
minimum control requirements during entry.
... an evident composite type of entry, which combines some of the desirable features of lifting and
no lifting trajectories, would be to enter first without lift but with a... drag device; then, when the
velocity is reduced to a certain value... the device is jettisoned or retracted, leaving a lifting vehicle...
for the remainder of the descent.
Entry vehicle design considerations
There are four critical parameters considered when designing a vehicle for atmospheric entry:
1.
2.
3.
4.
Peak heat flux
Heat load
Peak deceleration
Peak dynamic pressure
Peak heat flux and dynamic pressure selects the TPS material. Heat load selects the thickness of
the TPS material stack. Peak deceleration is of major importance for manned missions. The upper
limit for manned return to Earth from Low Earth Orbit (LEO) or lunar return is 10 Gs. For
Martian atmospheric entry after long exposure to zero gravity, the upper limit is 4 Gs. Peak
dynamic pressure can also influence the selection of the outermost TPS material if spallation is an
issue.
Starting from the principle of conservative design, the engineer typically considers two worst case
trajectories, the undershoot and overshoot trajectories. The overshoot trajectory is typically defined
as the shallowest allowable entry velocity angle prior to atmospheric skip-off. The overshoot
trajectory has the highest heat load and sets the TPS thickness. The undershoot trajectory is defined
by the steepest allowable trajectory. For manned missions the steepest entry angle is limited by the
peak deceleration. The undershoot trajectory also has the highest peak heat flux and dynamic
pressure. Consequently, the undershoot trajectory is the basis for selecting the TPS material. There
is no "one size fits all" TPS material. A TPS material that is ideal for high heat flux may be too
conductive (too dense) for a long duration heat load. A low density TPS material might lack the
tensile strength to resist spallation if the dynamic pressure is too high. A TPS material can perform
well for a specific peak heat flux, but fail catastrophically for the same peak heat flux if the wall
pressure is significantly increased (this happened with NASA's R-4 test spacecraft). Older TPS
materials tend to be more labor-intensive and expensive to manufacture compared to modern
materials. However, modern TPS materials often lack the flight history of the older materials (an
important consideration for a risk-averse designer). Based upon Allen and Eggers discovery,
maximum aeroshell bluntness (maximum drag) yields minimum TPS mass. Maximum bluntness
(minimum ballistic coefficient) also yields a minimal terminal velocity at maximum altitude (very
important for Mars EDL, but detrimental for military RVs). However, there is an upper limit to
bluntness imposed by aerodynamic stability considerations based upon shock wave detachment. A
shock wave will remain attached to the tip of a sharp cone if the cone's half-angle is below a critical
value. This critical half-angle can be estimated using perfect gas theory (this specific aerodynamic
instability occurs below hypersonic speeds). For a nitrogen atmosphere (Earth or Titan), the
maximum allowed half-angle is approximately 60°. For a carbon dioxide atmosphere (Mars or
Venus), the maximum allowed half-angle is approximately 70°. After shock wave detachment, an
entry vehicle must carry significantly more shocklayer gas around the leading edge stagnation point
(the subsonic cap). Consequently, the aerodynamic center moves upstream thus causing
aerodynamic instability. It is incorrect to reapply an aeroshell design intended for Titan entry
(Huygens probe in a nitrogen atmosphere) for Mars entry (Beagle-2 in a carbon dioxide
atmosphere). Prior to being abandoned, the Soviet Mars lander program achieved one successful
landing (Mars 3), on the second of three entry attempts (the others were Mars 2 and Mars 6). The
Soviet Mars landers were based upon a 60° half-angle aeroshell design.
A 45 degree half-angle sphere-cone is typically used for atmospheric probes (surface landing not
intended) even though TPS mass is not minimized. The rationale for a 45° half-angle is to have
either aerodynamic stability from entry-to-impact (the heat shield is not jettisoned) or a short-andsharp heat pulse followed by prompt heat shield jettison. A 45° sphere-cone design was used with
the DS/2 Mars impactor and Pioneer Venus Probes.
Notable atmospheric entry accidents

Voskhod 2 — The service module failed to detach for some time, but the crew survived.

Soyuz 1 — The attitude control system failed while still in orbit and later parachutes got
entangled during the emergency landing sequence (entry, descent and landing (EDL)
failure). Lone cosmonaut Vladimir Mikhailovich Komarov died.

Soyuz 5 — The service module failed to detach, but the crew survived.

Soyuz 11 - After Tri Module Sep, a valve was weakened by the blast and had failed on reentry. The cabin depressurized killing all three crew members.

Mars Polar Lander — Failed during EDL. The failure was believed to be the consequence
of a software error. The precise cause is unknown for lack of real-time telemetry.

Space Shuttle Columbia during STS-1 - a combination of launch damage, protruding
gap filler, and tile installation error resulted in serious damage to the orbiter, only some of
which the crew was privy to. Had the crew known the true extent of the damage before
attempting re-entry, they would have flown the shuttle to a safe altitude and then bailed
out. Nevertheless, re-entry was successful, and the orbiter proceeded to a normal landing.

Space Shuttle Columbia during STS-107 — The failure of an RCC panel on a wing
leading edge caused by debris impact at launch led to breakup of the orbiter on reentry
resulting in the deaths of all seven crew members.

Genesis — The parachute failed to deploy due to a G-switch having been installed
backwards (a similar error delayed parachute deployment for the Galileo Probe).
Consequently, the Genesis entry vehicle crashed into the desert floor. The payload was
damaged, but most scientific data were recoverable.

Soyuz TMA-11 (April 19, 2008) — The Soyuz propulsion module failed to separate
properly; fallback ballistic reentry was executed that subjected the crew to forces about
eight times that of gravity. The crew survived.
Uncontrolled and unprotected reentries
In 1978, Cosmos 954 reentered uncontrolled and crashed near Great Slave Lake in the Northwest
Territories of Canada. Cosmos 954 was nuclear powered and left radioactive debris near its impact
site.
In 1979, Skylab reentered uncontrolled, spreading debris across the Australian Outback, damaging
several buildings and killing a cow. The re-entry was a major media event largely due to the Cosmos
954 incident, but not viewed as much as a potential disaster since it did not carry nuclear fuel. The
city of Esperance, Western Australia, issued a fine for littering to the United States, which was
finally paid 30 years later (not by NASA, but by privately collected funds from radio listeners).
NASA had originally hoped to use a Space Shuttle mission to either extend its life or enable a
controlled reentry, but delays in the program combined with unexpectedly high solar activity made
this impossible.
On February 7, 1991 Salyut 7 underwent uncontrolled reentry with Kosmos 1686. It reentered
over Argentina and scattered much of its debris over the town of Capitan Bermudez.
Deorbit disposal
In 1971, the world's first space station Salyut 1 was deliberately de-orbited into the Pacific Ocean
following the Soyuz 11 accident. Its successor, Salyut 6, was de-orbited in a controlled manner as
well.
On June 4, 2000 the Compton Gamma Ray Observatory was deliberately de-orbited after one of
its gyroscopes failed. The debris that did not burn up fell harmlessly into the Pacific Ocean. The
observatory was still operational, but the failure of another gyroscope would have made de-orbiting
much more difficult and dangerous. With some controversy, NASA decided in the interest of
public safety that a controlled crash was preferable to letting the craft come down at random.
In 2001, the Russian Mir space station was deliberately de-orbited, and broke apart in the fashion
expected by the command center during atmospheric re-entry. Mir entered the Earth's atmosphere
on March 23, 2001, near Nadi, Fiji, and fell into the South Pacific Ocean.
On February 21, 2008, a disabled US spy satellite, USA 193, was successfully hit at an altitude of
approximately 246 kilometers (153 mi) by an SM-3 missile fired from the U.S. Navy cruiser Lake
Erie off the coast of Hawaii. The satellite was inoperative, having failed to reach its intended orbit
when it was launched in 2006. Due to its rapidly deteriorating orbit, it was destined for
uncontrolled reentry within a month. United States Department of Defense expressed concern
that the 1,000-pound (450 kg) fuel tank containing highly toxic hydrazine might survive reentry
to reach the Earth’s surface intact. Several governments including those of Russia, China, and
Belarus protested the action as a thinly-veiled demonstration of US anti-satellite capabilities. China
had previously caused an international incident when it tested an anti-satellite missile in 2007.
On September 7, 2011, NASA announced the impending uncontrolled re-entry of Upper
Atmosphere Research Satellite and noted that there was a small risk to the public. The
decommissioned satellite reentered the atmosphere on September 24, 2011, and some pieces are
presumed to have crashed into the South Pacific Ocean over a debris field 500 miles (800 km)
long.
2. Aerobraking
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis)
by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting
drag slows the spacecraft. Aerobraking is used when a spacecraft requires a low orbit after arriving
at a body with an atmosphere, and it requires less fuel than does the direct use of a rocket engine.
Method
When an interplanetary vehicle arrives at its destination, it must change its velocity to remain in
the vicinity of that body. When a low, near-circular orbit around a body with substantial gravity
(as is required for many scientific studies) is needed, the total required velocity changes can be on
the order of several kilometers per second. If done by direct propulsion, the rocket equation dictates
that a large fraction of the spacecraft mass must be fuel. This in turn means the spacecraft is limited
to a relatively small science payload and/or the use of a very large and expensive launcher. Provided
the target body has an atmosphere, aerobraking can be used to reduce fuel requirements. The use
of a relatively small burn allows the spacecraft to be captured into a very elongated elliptic orbit.
Aerobraking is then used to circularize the orbit. If the atmosphere is thick enough, a single pass
through it can be sufficient to slow a spacecraft as needed. However, aerobraking is typically done
with many orbital passes through a higher altitude, and therefore thinner region of the atmosphere.
This is done to reduce the effect of frictional heating, and because unpredictable turbulence effects,
atmospheric composition, and temperature make it difficult to accurately predict the decrease in
speed that will result from any single pass. When aerobraking is done in this way, there is sufficient
time after each pass to measure the change in velocity and make any necessary corrections for the
next pass. Achieving the final orbit using this method takes a long time (e.g., over six months when
arriving at Mars), and may require several hundred passes through the atmosphere of the planet or
moon. After the last aerobraking pass, the spacecraft must be given more kinetic energy via rocket
engines in order to raise the periapsis above the atmosphere. The kinetic energy dissipated by
aerobraking is converted to heat, meaning that a spacecraft using the technique needs to be capable
of dissipating this heat. The spacecraft must also have sufficient surface area and structural strength
to produce and survive the required drag, but the temperatures and pressures associated with
aerobraking are not as severe as those of atmospheric reentry or aerocapture. Simulations of the
Mars Reconnaissance Orbiter aerobraking use a force limit of 0.35 N per square meter with a
spacecraft cross section of about 37 m², equate to a maximum drag force of about 7.4 N, and a
maximum expected temperature as 340 °F (170 °C). The force density (i.e. pressure), of roughly
0.2 N (0.04 lbf) per square meter, that was exerted on the Mars Observer, during aerobraking is
comparable to the aerodynamic resistance of moving at 0.6 m/s (2.16 kph, or 1.34 mph), at sea
level on Earth... or basically the aerodynamic resistance you experience when walking slowly.
Missions of Spacecraft
Although the theory of aerobraking is well developed, utilising the technique is difficult because a
very detailed knowledge of the character of the target planet's atmosphere is needed in order to
plan the maneuver correctly. Currently, the deceleration is monitored during each maneuver and
plans are modified accordingly. Since no spacecraft can yet aerobrake safely on its own, this requires
constant attention from both human controllers and the Deep Space Network. This is particularly
true near the end of the process, when the drag passes are relatively close together (only about 2
hours apart for Mars). NASA has used aerobraking four times to modify a spacecraft’s orbit to one
with lower energy, reduced apoapsis altitude, and smaller orbit. On 19 March 1991, aerobraking
was demonstrated by the Hiten spacecraft. This was the first aerobraking maneuver by a deep space
probe. Hiten (a.k.a. MUSES-A) was launched by the Institute of Space and Astronautical Science
(ISAS) of Japan. Hiten flew by the Earth at an altitude of 125.5 km over the Pacific at 11.0 km/s.
Atmospheric drag lowered the velocity by 1.712 m/s and the apogee altitude by 8665 km. Another
aerobraking maneuver was conducted on 30 March.
In May 1993, aerobraking was used during the extended Venusian mission of the Magellan
spacecraft. It was used to circularize the orbit of the spacecraft in order to increase the precision of
the measurement of the gravity field. The entire gravity field was mapped from the circular orbit
during a 243-day cycle of the extended mission. During the termination phase of the mission, a
"windmill experiment" was performed: Atmospheric molecular pressure exerts a torque via the
then windmill-sail-like oriented solar cell wings, the necessary counter-torque to keep the sonde
from spinning is measured.
In 1997, the Mars Global Surveyor (MGS) orbiter was the first spacecraft to use aerobraking as
the main planned technique of orbit adjustment. The MGS used the data gathered from the
Magellan mission to Venus to plan its aerobraking technique. The spacecraft used its solar panels
as "wings" to control its passage through the tenuous upper atmosphere of Mars and lower the
apoapsis of its orbit over the course of many months. Unfortunately, a structural failure shortly
after launch severely damaged one of the MGS's solar panels and necessitated a higher aerobraking
altitude (and hence one third the force ) than originally planned, significantly extending the time
required to attain the desired orbit. More recently, aerobraking was used by the Mars Odyssey and
Mars Reconnaissance Orbiter spacecraft, in both cases without incident. In 2014, an aerobraking
experiment was successfully performed near the end of the mission of the ESA probe Venus
Express.
Aerodynamic braking
Aerodynamic braking is a method used in landing aircraft to assist the wheel brakes in stopping
the plane. It is often used for short runway landings or when conditions are wet, icy or slippery.
Aerodynamic braking is performed immediately after the rear wheels (main mounts) touch down,
but before the nose wheel drops. The pilot begins to pull back on the stick, applying elevator
pressure to hold the nose high. The nose-high attitude exposes more of the craft's surface-area to
the flow of air, which produces greater drag, helping to slow the plane. The raised elevators also
cause air to push down on the rear of the craft, forcing the rear wheels harder against the ground,
which aids the wheel brakes by helping to prevent skidding. The pilot will usually continue to hold
back on the stick even after the elevators lose their authority, and the nose wheel drops, to keep
added pressure on the rear wheels.
Aerodynamic braking is a common braking technique during landing, which can also help to
protect the wheel brakes and tyres from excess wear, or from locking up and sending the craft
sliding out of control. It is often used by private pilots, commercial planes, fighter aircraft, and was
used by the space shuttles during landings.
3. Booster (rocketry)
A booster rocket (or engine) is either the first stage of a multistage launch vehicle, or else a shorterburning rocket used in parallel with longer-burning sustainer rockets to augment the space vehicle's
takeoff thrust and payload capability. (Boosters used in this way are frequently designated "zero
stages".) Boosters are traditionally necessary to launch spacecraft into low Earth orbit (absent a
single-stage-to-orbit design), and are certainly necessary for a space vehicle to go beyond Earth
orbit. The booster is dropped to fall back to Earth once its fuel is expended, a point known as
booster engine cut-off (BECO). The rest of the launch vehicle continues flight with its core or
upper-stage engines. The booster may be recovered and reused, as in the case of the Space Shuttle.
Strap-on boosters are sometimes used to augment the payload or range capability of jet aircraft
(usually military).
Recoverable boosters
The booster casings for the Space Shuttle Solid Rocket Booster were recovered and refurbished for
reuse from 1981–2011 as part of the Space Shuttle program. In a new development program
initiated in 2011, SpaceX developed technologies to facilitate the return, vertical landing, and
recovery for low-cost and rapid reuse of a recoverable booster. The program was intended to reduce
launch prices significantly, opening new markets for the use of space. A multi-year, multi-element
test program was conducted in 2013–2016, with first successful return in 2015, and multiple
returns both on land and landing platforms at sea some distance away from the launch site during
2016.
Uses
Rocket boosters used on aircraft are known as Jet-Assisted TakeOff (JATO) rockets.
Various missiles also use solid rocket boosters.
Examples are:



2K11 (SA-4) which uses SRBs as a first stage, and then a ramjet.
S-200 (SA-5) which uses SRBs as the first stage, followed by a liquid fuel rocket.
Surface-launched versions of the turbojet powered Boeing Harpoon use an SRB.
3. Launch Tower
A service structure, or supply tower or launch tower, is a structure built on a rocket launch pad to
facilitate fueling and loading of cargo and crew into a spacecraft.
A supply tower also usually includes an elevator which allows maintenance and crew access.
Immediately before ignition of the rocket's motors, all connections between the tower and the craft
are severed, and the bridges over which these connections pass often quickly swing away to prevent
damage to the structure or vehicle. In contrast with launch towers, service structure towers do not
guide rockets as they lift off.
Examples:
Kennedy Space Center
The structures at the Kennedy Space Center Launch Complex 39 pads include a rotating service
structure that is moved in place around the shuttle stack for the period of time that the space craft
sits on the pad prior to launch, usually several weeks. That structure is rotated back out of the way
several hours prior to the launch while the fixed service structure remains in place at all times.
Unmanned and manned rockets such as the Delta, Saturn V also used fixed and mobile service
structure configurations with the mobile portion moved away from the vehicle several hours before
launch. The Saturn's "fixed service structure", however, was formally called the launch umbilical
tower (LUT) and was fixed to a Mobile Launcher Platform.
White room
The 'White Room' is the small area used by NASA astronauts to access the spacecraft. The room
takes its name from the white paint. First used in Project Gemini, its use and white color continued
to be included on supply towers through subsequent programs up to and including the Space
Shuttle program.
Rooms are located at the end of the walkway extended from the fixed service structure. In this
room astronauts make final preparations before entering the spacecraft such as donning parachute
packs, putting on helmets and detaching portable air conditioning units.
Baikonur Cosmodrome
Soviet-and Russian-designed service structures such those at the Baikonur Cosmodrome stand
while servicing the vehicle. The entire structure pivots outward and downward out of the way at
launch time.
4. Reusable launch system
A reusable launch system (RLS, or reusable launch vehicle, RLV) is a launch system which is
capable of launching a payload into space more than once. This contrasts with expendable launch
systems, where each launch vehicle is launched once and then discarded.
No completely reusable orbital launch system has ever been created; however, several partially
reusable launch systems have existed. The Space Shuttle was partially reusable: the orbiter, which
included the Space Shuttle main engines, and the two solid rocket boosters, were reused after
several months of refitting work for each launch. However, the external tank and launch vehicle
load frame were discarded after each flight. The Falcon 9 rocket is designed to have a reusable first
stage; several of these stages have been safely returned to land after launch. However, as of 2016,
none of these first stages have yet been reused. Several partially reusable systems, such as Adeline
and Vulcan, are currently under development; one fully reusable system, the Mars Colonial
Transporter, is also under development.
Orbital RLVs are thought to provide the possibility of low cost and highly reliable access to space.
However, reusability implies weight penalties such as non-ablative reentry shielding and possibly
a stronger structure to survive multiple uses, and given the lack of experience with these vehicles,
the actual costs and reliability are yet to be seen.
History
In the first half of the twentieth century, popular science fiction often depicted space vehicles as
either single-stage reusable rocket ships which could launch and land vertically (SSTO VTVL), or
single-stage reusable rocket planes which could launch and land horizontally (SSTO HTHL).
The realities of early engine technology with low specific impulse or insufficient thrust-to-weight
ratio to escape Earth's gravity well, compounded by construction materials without adequate
performance (strength, stiffness, heat resistance) and low weight, seemingly rendered that original
single-stage reusable vehicle vision impossible.
However, advances in materials and engine technology have rendered this concept potentially
feasible.
Before VTVL SSTO designs came the partially reusable multi-stage NEXUS launcher by Krafft
Arnold Ehricke. The pioneer in the field of VTVL SSTO, Philip Bono, worked at Douglas. Bono
proposed several launch vehicles including: ROOST, ROMBUS, Ithacus, Pegasus and SASSTO.
Most of his vehicles combined similar innovations to achieve SSTO capability. Bono proposed:





Plug nozzle engines to retain high specific impulse at all altitudes.
Base first reentry which allowed the reuse of the engine as a heat shield, lowering required
heat shield mass.
Use of spherical tanks and stubby shape to reduce vehicle structural mass further.
Use of drop tanks to increase range.
Use of in-orbit refueling to increase range.
Bono also proposed the use of his vehicles for space launch, rapid intercontinental military
transport (Ithacus), rapid intercontinental civilian transport (Pegasus), even Moon and Mars
missions. In Europe, Dietrich Koelle, inspired by Bono's SASSTO design, proposed his own
VTVL vehicle named BETA.
Before HTHL SSTO designs came Eugen Sänger and his Silbervogel ("Silverbird") suborbital skip
bomber. HTHL vehicles which can reach orbital velocity are harder to design than VTVL due to
their higher vehicle structural weight. This led to several multi-stage prototypes such as a suborbital
X-15. Aerospaceplane being one of the first HTHL SSTO concepts. Proposals have been made to
make such a vehicle more viable including:



Rail boost (e.g. 270 m/s at 3000 m on a mountain allowing 35% less SSTO takeoff mass
for a given payload in one NASA study)
Use of lifting body designs to reduce vehicle structural mass.
Use of in-flight refueling.
Other launch system configuration designs are possible such as horizontal launch with vertical
landing (HTVL) and vertical launch with horizontal landing (VTHL). One of the few HTVL
vehicles is the 1960s concept spacecraft Hyperion SSTO, designed by Philip Bono. X-20 DynaSoar is an early example of a VTHL design, while the HL-20 and X-34 are examples from the
1990s. As of February 2010, the VTHL X-37 has completed initial development and flown an
initial classified orbital mission of over seven month’s duration. Currently proposed VTHL
manned spaceplanes include the Dream Chaser and Prometheus, both circa 2010 concept space
planes proposed to NASA under the CCDev program.
The late 1960s saw the start of the Space Shuttle design process. From an initial multitude of ideas
a two-stage reusable VTHL design was pushed forward that eventually resulted in a reusable orbiter
payload spacecraft and reusable solid rocket boosters. The external tank and the launch vehicle
load frame were discarded, and the parts that were reusable took a 10,000-person group nine
months to refurbish for flight. So the space shuttle ended up costing a billion dollars per flight.
Early studies from 1980 and 1982 proposed in-space uses for the tank to be re-used in space for
various applications but NASA never pursued those options beyond the proposal stage.
During the 1970s further VTVL and HTHL SSTO designs were proposed for solar power satellite
and military applications. There was a VTVL SSTO study by Boeing. HTHL SSTO designs
included the Rockwell Star-Raker and the Boeing HTHL SSTO study. However the focus of all
space launch funding in the United States on the Shuttle killed off these prospects. The Soviet
Union followed suit with Buran. Others preferred expendables for their lower design risk, and
lower design cost.
Eventually the Shuttle was found to be expensive to maintain, even more expensive than an
expendable launch system would have been. The cancellation of a Shuttle-Centaur rocket after the
loss of Challenger also caused an hiatus that would make it necessary for the United States military
to scramble back towards expendables to launch their payloads. Many commercial satellite
customers had switched to expendables even before that, due to unresponsiveness to customer
concerns by the Shuttle launch system.
In 1986 President Ronald Reagan called for an airbreathing scramjet plane to be built by the year
2000, called NASP/X-30 that would be capable of SSTO. Based on the research project copper
canyon the project failed due to severe technical issues and was cancelled in 1993.
This research may have inspired the British HOTOL program, which rather than airbreathing to
high hypersonic speeds as with NASP, proposed to use a precooler up to Mach 5.5. The program's
funding was canceled by the British government when the research identified some technical risks
as well as indicating that that particular vehicle architecture would only be able to deliver a
relatively small payload size to orbit.
When the Soviet Union collapsed in the early nineties, the cost of Buran became untenable. Russia
has only used pure expendables for space launch since.
The 1990s saw interest in developing new reusable vehicles. The military Strategic Defense
Initiative ("Star Wars") program "Brilliant Pebbles" required low cost, rapid turnaround space
launch. From this requirement came the McDonnell Douglas Delta Clipper VTVL SSTO
proposal. The DC-X prototype for Delta Clipper demonstrated rapid turnaround time and that
automatic computer control of such a vehicle was possible. It also demonstrated it was possible to
make a reusable space launch vehicle which did not require a large standing army to maintain like
the Shuttle.
In mid-1990, further British research and major reengineering to avoid deficiencies of the
HOTOL design led to the far more promising Skylon design, with much greater payload.
From the commercial side, large satellite constellations such as Iridium satellite constellation were
proposed which also had low cost space access demands. This fueled a private launch industry,
including partially reusable vehicle players, such as Rocketplane Kistler, and reusable vehicle
players such as Rotary Rocket.
The end of that decade saw the implosion of the satellite constellation market with the bankruptcy
of Iridium. In turn the nascent private launch industry collapsed. The fall of the Soviet Union
eventually had political ripples which led to a scaling down of ballistic missile defense, including
the demise of the "Brilliant Pebbles" program. The military decided to replace their aging
expendable launcher workhorses, evolved from ballistic missile technology, with the EELV
program. NASA proposed riskier reusable concepts to replace Shuttle, to be demonstrated under
the X-33 and X-34 programs.
The 21st century saw rising costs and teething problems lead to the cancellation of both X-33 and
X-34. Then the Space Shuttle Columbia disaster and another grounding of the fleet. The Shuttle
design was now over 20 years old and in need of replacement. Meanwhile, the military EELV
program churned out a new generation of better expendables. The commercial satellite market is
depressed due to a glut of cheap expendable rockets and there is a dearth of satellite payloads.
Against this backdrop came the Ansari X Prize contest, inspired by the aviation contests made in
the early 20th century. Many private companies competed for the Ansari X Prize, the winner being
Scaled Composites with their reusable HTHL SpaceShipOne. It won the ten million dollars, by
reaching 100 kilometers in altitude twice in a two-week period with the equivalent of three people
on board, with no more than ten percent of the non-fuel weight of the spacecraft replaced between
flights. While SpaceShipOne is suborbital like the X-15, some hope the private sector can
eventually develop reusable orbital vehicles given enough incentive. SpaceX is a recent player in
the private launch market succeeding in converting its Falcon 9 expendable launch vehicle into a
partially reusable vehicle by returning the first stage for reuse.
On 23 November 2015, Blue Origin New Shepard rocket became the first proven Vertical Takeoff Vertical Landing (VTVL) rocket which can reach space, by passing Kármán line (100
kilometres), reaching 329,839 feet (100.5 kilometers). Previous VTVL record was in 1994, the
McDonnell Douglas DC-X ascended to an altitude of about 3.1 kilometers before successfully
landing.
Orbital reusable launchers
1. Under development

RLV-TD, (India): On 23 May 2016, ISRO successfully performed test flight of India’s
first reusable launch vehicle that operates at hypersonic speed.

Adeline - Reusable launch system concept developed by Airbus Defence and Space.

Avatar RLV - Under development, first scaled-down demonstration flight planned in
2016.
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Blue Origin is developing a reusable booster system, as of November 2015. Blue Origin
New Shepard rocket is the first rocket successfully launched and which is proven to be able
to land vertically on earth VTVL after reaching space, by passing Kármán line.
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As of 2014, China is working on a project to recover rocket boosters, using a "paraglidertype wings" approach. Powered flight tests are in the future, and the process is expect to
take until approximately 2018.
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Skylon (spacecraft) (proposed airbreathing SSTO spaceplane)
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SpaceX reusable rocket launching system—(currently in development and test)—is
planned for use on both the Falcon 9 and Falcon Heavy launch vehicles. A secondgeneration VTVL reusable design was publicly announced in 2011. The low-altitude flight
test program of an experimental technology-demonstrator launch vehicle began in 2012,
with more extensive high-altitude over-water flight testing planned to begin in mid-2013,
and continue on each subsequent Falcon 9 flight. On December 21, 2015, SpaceX
successfully landed a Falcon 9 first stage after it boosted 11 commercial satellites into low
earth orbit on Falcon 9 Flight 20.
Swiss Space Systems is developing launching system including the suborbital spaceplane
SOAR. The first 2 stages, an Airbus 300 and SOAR, are completely reusable.
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zero2infinity is developing a launching system called bloostar based on the rockoon
system, which consists in elevating to the near space the launcher using a high-altitude
balloon and once there launch a multi-stage rocket to put a satellite into orbit.
Future space technologies
1. Asteroid mining technology
Asteroid mining is a concept that involves the extraction of useful materials from asteroids. Due
to their accessibility, near-Earth asteroids (those asteroids that pass near the Earth, also known as
NEAs) are a particularly accessible subset of the asteroids that provide potentially attractive targets
for resources to support space industrialization. Many materials could be extracted and processed
from NEAs which are useful for propulsion, construction life support, agriculture, metallurgy,
semiconductors, and precious and strategic metals (see Table 1). Volatiles such as hydrogen and
methane could be used to produce rocket propellant to transport spacecraft between space habitats,
Earth, the Moon, the asteroids, and beyond. Rare-earth metals could be used to manufacture
structural materials as well as solar photovoltaic arrays which could be used to power space or lunar
habitats. These solar cells could also be used in a constellation of solar power satellites in orbit
around the Earth in order to provide electrical power for its inhabitants. Precious metals such as
platinum, platinum-group metals (PGMs), and gold are also available.
The shown below provides Useful Products Obtainable from NEAs. The volatiles and metals
found in asteroids are categorized by their primary use. The molecules and elements shown here
are based on the spectral properties of the entire asteroid population and chemical analysis of
meteorites on Earth, which are believed to come from asteroids.
Volatiles
Primary Use
Molecules
Life Support Propellant Agriculture Oxidizer Refrigerant Metallurgy
H2O, N2, O2
H2, O2, CH4, CH3OH CO2, NH4OH, NH3 H2O2 SO2 CO, H2S, Ni(CO)4, Fe(CO)5, H2SO4, SO3
Metals and Semiconductors
Primary Use
Element
Construction Precious Metals Semiconductors Fe, Ni
Au, Pt, Pd, Os, Ir, Rh, Ru, Re, Ge Si, Al, P, Ga, Ge, Cd, Cu, As, Se, In, Sb, Te
Mining considerations
Mainly there are three options for mining:
1. Bring raw asteroidal material to Earth for use.
2. Process it on-site to bring back only processed materials, and perhaps produce propellant
for the return trip.
3. Transport the asteroid to a safe orbit around the Moon, Earth or to the ISS. This can
hypothetically allow for most materials to be used and not wasted. Along these lines, NASA
has proposed a potential future space mission known as the Asteroid Redirect Mission,
although the primary focus of this mission is on retrieval. The House of Representatives
recently deleted a line item for the ARP budget from NASA's FY 2017 budget request.
Processing in situ for the purpose of extracting high-value minerals will reduce the energy
requirements for transporting the materials, although the processing facilities must first be
transported to the mining site. Mining operations require special equipment to handle the
extraction and processing of ore in outer space. The machinery will need to be anchored to the
body, but once in place, the ore can be moved about more readily due to the lack of gravity.
However, no techniques for refining ore in zero gravity currently exist. Docking with an asteroid
might be performed using a harpoon-like process, where a projectile would penetrate the surface
to serve as an anchor; then an attached cable would be used to winch the vehicle to the surface, if
the asteroid is both penetrable and rigid enough for a harpoon to be effective. Due to the distance
from Earth to an asteroid selected for mining, the round-trip time for communications will be
several minutes or more, except during occasional close approaches to Earth by near-Earth
asteroids. Thus any mining equipment will either need to be highly automated, or a human
presence will be needed nearby. Humans would also be useful for troubleshooting problems and
for maintaining the equipment. On the other hand, multi-minute communications delays have
not prevented the success of robotic exploration of Mars, and automated systems would be much
less expensive to build and deploy.
Technology being developed by Planetary Resources to locate and harvest these asteroids has
resulted in the plans for three different types of satellites:
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Arkyd Series 100 (The Leo Space telescope) is a less expensive instrument that will be used
to find, analyze, and see what resources are available on nearby asteroids.
Arkyd Series 200 (The Interceptor) Satellite that would actually land on the asteroid to get
a closer analysis of the available resources.
Arkyd Series 300 (Rendezvous Prospector) Satellite developed for research and finding
resources deeper in space.
Technology being developed by Deep Space Industries to examine, sample, and harvest asteroids
is divided into three families of spacecrafts:
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FireFlies are triplets of nearly identical spacecraft in CubeSat form launched to different
asteroids to rendezvous and examine them.
DragonFlies also are launched in waves of three nearly identical spacecraft to gather small
samples (5–10 kg) and return them to Earth for analysis.
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Harvestors voyage out to asteroids to gather hundreds of tons of material for return to high
Earth orbit for processing.
Asteroid mining could potentially revolutionize space exploration. The C-type asteroids's high
abundance of water could be used to produce fuel by splitting water into hydrogen and oxygen.
This would make space travel a more feasible option by lowering cost of fuel, although cost of fuel
is a relatively insignificant factor in the overall cost of a manned space mission.
Extraction techniques
1) Surface mining
On some types of asteroids, material may be scraped off the surface using a scoop or auger, or for
larger pieces, an "active grab."There is strong evidence that many asteroids consist of rubble piles,
making this approach possible.
2) Shaft mining
A mine can be dug into the asteroid, and the material extracted through the shaft. This requires
precise knowledge to engineer accuracy of astro-location under the surface regolith and a
transportation system to carry the desired ore to the processing facility.
3) Magnetic rakes
Asteroids with a high metal content may be covered in loose grains that can be gathered by means
of a magnet.
4) Heating
For asteroids such as carbonaceous chondrites that contain hydrated minerals, water and other
volatiles can be extracted simply by heating. A water extraction test in 2016 by Honeybee Robotics
used asteroid regolith simulant developed by Deep Space Industries and the University of Central
Florida to match the bulk mineralogy of a particular carbonaceous meteorite. Although the
simulant was physically dry (i.e., it contained no water molecules adsorbed in the matrix of the
rocky material), heating to about 510 °C released hydroxyl, which came and sulphur compounds.
The vapor was condensed into liquid water filling the collection containers out as substantial
amounts of water vapor from the molecular structure of phyllosilicate clays, demonstrating the
feasibility of mining water from certain classes of physically dry asteroids. For volatile materials in
extinct comets, heat can be used to melt and vaporize the matrix.
5) Extraction using the Mond process
The nickel and iron of an iron rich asteroid could be extracted by the Mond process. This involves
passing carbon monoxide over the asteroid at a temperature between 50 and 60 °C, then nickel
and iron can be removed from the gas again at higher temperatures, perhaps in an attached printer,
and platinum, gold etc. left as a residue.
6) Self-replicating machines
A 1980 NASA study entitled Advanced Automation for Space Missions proposed a complex
automated factory on the Moon that would work over several years to build 80% of a copy of itself,
the other 20% being imported from Earth since those more complex parts (like computer chips)
would require a vastly larger supply chain to produce. Exponential growth of factories over many
years could refine large amounts of lunar (or asteroidal) regolith. Since 1980 there has been major
progress in miniaturization, nanotechnology, materials science, and additive manufacturing, so it
may be possible to achieve 100% "closure" with a reasonably small mass of hardware, although
these technology advancements are themselves enabled on Earth by expansion of the supply chain
so it needs further study. A NASA study in 2012 proposed a "bootstrapping" approach to establish
an in-space supply chain with 100% closure, suggesting it could be achieved in only two to four
decades with low annual cost. A study in 2016 again claimed it is possible to complete in just a few
decades because of ongoing advances in robotics, and it argued it will provide benefits back to the
Earth including economic growth, environmental protection, and provision of clean energy while
also providing humanity protection against existential threats.
Potential targets
According to the Asterank database, the following asteroids are considered the best targets for
mining if maximum cost-effectiveness is to be achieved:
Asteroid
Est. Value Est. Profit Δv
(US$)
(US$)
(km/s)
Composition
Ryugu
95 billion
35 billion
4.663
Nickel, iron, cobalt, water, nitrogen,
hydrogen, ammonia
1989 ML
14 billion
4 billion
4.888
Nickel, iron, cobalt
Nereus
5 billion
1 billion
4.986
Nickel, iron, cobalt
Didymos
84 billion
22 billion
5.162
Nickel, iron, cobalt
2011
UW158
8 billion
2 billion
5.187
Platinum, nickel, iron, cobalt
Anteros
5570 billion
1250 billion
5.439
magnesium silicate, aluminum, iron
silicate
2001 CC21 147 billion
30 billion
5.636
magnesium silicate, aluminum, iron
silicate
1992 TC
17 billion
5.647
Nickel, iron, cobalt
2001 SG10 4 billion
0.6 billion
5.880
Nickel, iron, cobalt
2002 DO3
0.06 billion
5.894
Nickel, iron, cobalt
84 billion
0.3 billion
Missions
Ongoing and planned
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OSIRIS-REx - planned NASA asteroid sample return mission (launch in September 2016)
Hayabusa 2 - ongoing JAXA asteroid sample return mission (arriving at the target in 2018)
Asteroid Redirect Mission - potential future space mission proposed by NASA (if funded,
the mission would be launched in December 2020)
Fobos-Grunt 2 - planned Roskosmos sample return mission to Phobos (launch in 2024)
Completed
First successful missions by country:
Nation Flyby
Orbit
Landing
Sample return
USA
ICE (1985)
NEAR (1997)
NEAR (2001)
Stardust (2006)
Japan
Suisei (1986)
Hayabusa (2005) Hayabusa (2005) Hayabusa (2010)
EU
ICE (1985)
Rosetta (2014)
USSR
Vega 1 (1986)
China
Chang'e 2 (2012)
Rosetta (2014)
2. Space-based solar power
Space-based solar power (SBSP) is the concept of collecting solar power in space (using an "SPS",
that is, a "solar-power satellite" or a "satellite power system") for use on Earth. SBSP would differ
from current solar collection methods in that the means used to collect energy would reside on an
orbiting satellite instead of on Earth's surface. Some projected benefits of such a system are a higher
collection rate and a longer collection period due to the lack of a diffusing atmosphere and night
time in space. Part of the solar energy (55–60%) is lost on its way through the atmosphere by the
effects of reflection and absorption. Space-based solar power systems convert sunlight to
microwaves outside the atmosphere, avoiding these losses, and the downtime (and cosine losses,
for fixed flat-plate collectors) due to the Earth's rotation.
Besides the cost of implementing such a system, SBSP also introduces several new hurdles,
primarily the problem of transmitting energy from orbit to Earth's surface for use. Since wires
extending from Earth's surface to an orbiting satellite are neither practical nor feasible with current
technology, SBSP designs generally include the use of some manner of wireless power transmission.
The collecting satellite would convert solar energy into electrical energy on board, powering a
microwave transmitter or laser emitter, and focus its beam toward a collector on Earth's surface.
Radiation and micrometeoroid damage could also become concerns for SBSP.
SBSP is considered a form of sustainable or green energy, renewable energy, and is occasionally
considered among climate engineering proposals. It is attractive to those seeking large-scale
solutions to anthropogenic climate change or fossil fuel depletion (such as peak oil). SBSP is being
actively pursued by Japan and China. In 2008 Japan passed its Basic Space Law which established
Space Solar Power as a national goal and JAXA has a roadmap to commercial SBSP. In 2015 the
China Academy for Space Technology (CAST) briefed their roadmap at the International Space
Development Conference (ISDC) where they showcased their road map to a 1 GW commercial
system in 2050 and unveiled a video and description of their design. A proposal for the United
States to lead in Space Solar Power has recently received high level attention after it won the D3
(Diplomacy, Development, Defense) competition sponsored by the Secretary of Defense, Secretary
of State, and USAID Director. As of May 21, 2015, there was an active petition on Change.org
and a second active petition at Whitehouse website.
History
In 1941, science fiction writer Isaac Asimov published the science fiction short story "Reason", in
which a space station transmits energy collected from the Sun to various planets using microwave
beams. The SBSP concept, originally known as satellite solar-power system (SSPS), was first
described in November 1968. In 1973 Peter Glaser was granted U.S. patent number 3,781,647
for his method of transmitting power over long distances (e.g. from an SPS to Earth's surface)
using microwaves from a very large antenna (up to one square kilometer) on the satellite to a much
larger one, now known as a rectenna, on the ground. Glaser then was a vice president at Arthur D.
Little, Inc. NASA signed a contract with ADL to lead four other companies in a broader study in
1974. They found that, while the concept had several major problems – chiefly the expense of
putting the required materials in orbit and the lack of experience on projects of this scale in space
– it showed enough promise to merit further investigation and research.
Space Solar Power Exploratory Research and Technology program
In 1999, NASA's Space Solar Power Exploratory Research and Technology program (SERT) was
initiated for the following purposes:
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Perform design studies of selected flight demonstration concepts.
Evaluate studies of the general feasibility, design, and requirements.
Create conceptual designs of subsystems that make use of advanced SSP technologies to
benefit future space or terrestrial applications.
Formulate a preliminary plan of action for the U.S. (working with international partners)
to undertake an aggressive technology initiative.
Construct technology development and demonstration roadmaps for critical Space Solar
Power (SSP) elements.
SERT went about developing a solar power satellite (SPS) concept for a future gigawatt space
power system, to provide electrical power by converting the Sun's energy and beaming it to Earth's
surface, and provided a conceptual development path that would utilize current technologies.
SERT proposed an inflatable photovoltaic gossamer structure with concentrator lenses or solar heat
engines to convert sunlight into electricity. The program looked both at systems in sunsynchronous orbit and geosynchronous orbit. Some of SERT's conclusions:
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The increasing global energy demand is likely to continue for many decades resulting in
new power plants of all sizes being built.
The environmental impact of those plants and their impact on world energy supplies and
geopolitical relationships can be problematic.
Renewable energy is a compelling approach, both philosophically and in engineering terms.
Many renewable energy sources are limited in their ability to affordably provide the base
load power required for global industrial development and prosperity, because of inherent
land and water requirements.
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Based on their Concept Definition Study, space solar power concepts may be ready to
reenter the discussion.
Solar power satellites should no longer be envisioned as requiring unimaginably large initial
investments in fixed infrastructure before the emplacement of productive power plants can
begin.
Space solar power systems appear to possess many significant environmental advantages
when compared to alternative approaches.
The economic viability of space solar power systems depends on many factors and the
successful development of various new technologies (not least of which is the availability
of much lower cost access to space than has been available), however, the same can be said
of many other advanced power technologies options.
Space solar power may well emerge as a serious candidate among the options for meeting
the energy demands of the 21st century. Space Solar Power Satellite Technology
Development at the Glenn Research Center—An Overview. James E. Dudenhoefer and
Patrick J. George, NASA Glenn Research Center, Cleveland, Ohio.
Launch costs in the range of $100–$200 per kilogram of payload to low Earth orbit are
needed if SPS are to be economically viable.
Japan Aerospace Exploration Agency
The May 2014 IEEE Spectrum magazine carried a lengthy article "It's Always Sunny in Space" by
Dr. Susumu Sasaki. The article stated, "It's been the subject of many previous studies and the stuff
of sci-fi for decades, but space-based solar power could at last become a reality—and within 25
years, according to a proposal from researchers at the Tokyo-based Japan Aerospace Exploration
Agency (JAXA)."
JAXA announced on 12 March 2015 that they wirelessly beamed 1.8 kilowatts 50 meters to a small
receiver by converting electricity to microwaves and then back to electricity. This is the standard
plan for this type of power. On 12 March 2015 Mitsubishi Heavy Industries demonstrated
transmission of 10 kilowatts (kW) of power to a receiver unit located at a distance of 500 meters
(m) away.
Challenges
Potential
The SBSP concept is attractive because space has several major advantages over the Earth's surface
for the collection of solar power:
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Its always solar noon in space and full sun.
Collecting surfaces could receive much more intense sunlight, owing to the lack of
obstructions such as atmospheric gasses, clouds, dust and other weather events.
Consequently, the intensity in orbit is approximately 144% of the maximum attainable
intensity on Earth's surface.
A satellite could be illuminated over 99% of the time, and be in Earth's shadow a maximum
of only 72 minutes per night at the spring and fall equinoxes at local midnight. Orbiting
satellites can be exposed to a consistently high degree of solar radiation, generally for 24
hours per day, whereas the average earth surface solar panels currently collect power for an
average of 29% per day.
Power could be relatively quickly redirected directly to areas that need it most. A collecting
satellite could possibly direct power on demand to different surface locations based on
geographical baseload or peak load power needs. Typical contracts would be for baseload,
continuous power, since peaking power is ephemeral.
Elimination of plant and wildlife interference.
With very large scale implementations, especially at lower altitudes, it potentially can
reduce incoming solar radiation reaching earth's surface. This would be desirable for
counteracting the effects of global warming.
Drawbacks
The SBSP concept also has a number of problems:
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The large cost of launching a satellite into space
Inaccessibility: Maintenance of an earth-based solar panel is relatively simple, but
construction and maintenance on a solar panel in space would typically be done
telerobotically. In addition to cost, astronauts working in GEO orbit are exposed to
unacceptably high radiation dangers and risk and cost about one thousand times more
than the same task done telerobotically.
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The space environment is hostile; panels suffer about 8 times the degradation they
would on Earth (except at orbits that are protected by the magnetosphere).
Space debris is a major hazard to large objects in space, and all large structures such as
SBSP systems have been mentioned as potential sources of orbital debris.
The broadcast frequency of the microwave downlink (if used) would require isolating
the SBSP systems away from other satellites. GEO space is already well used and it is
considered unlikely the ITU would allow an SPS to be launched.
The large size and corresponding cost of the receiving station on the ground.
Energy losses during several phases of conversion from "photon to electron to photon
back to electron," as Elon Musk has stated.
Design
Space-based solar power essentially consists of three elements:
1. collecting solar energy in space with reflectors or inflatable mirrors onto solar cells
2. wireless power transmission to Earth via microwave or laser
3. receiving power on Earth via a rectenna, a microwave antenna
The space-based portion will not need to support itself against gravity (other than relatively weak
tidal stresses). It needs no protection from terrestrial wind or weather, but will have to cope with
space hazards such as micrometeors and solar flares. Two basic methods of conversion have been
studied: photovoltaic (PV) and solar dynamic (SD). Most analyses of SBSP have focused on
photovoltaic conversion using solar cells that directly convert sunlight into electricity. Solar
dynamic uses mirrors to concentrate light on a boiler. The use of solar dynamic could reduce mass
per watt. Wireless power transmission was proposed early on as a means to transfer energy from
collection to the Earth's surface, using either microwave or laser radiation at a variety of
frequencies.
Microwave power transmission
William C. Brown demonstrated in 1964, during Walter Cronkite's CBS News program, a
microwave-powered model helicopter that received all the power it needed for flight from a
microwave beam. Between 1969 and 1975, Bill Brown was technical director of a JPL Raytheon
program that beamed 30 kW of power over a distance of 1 mile (1.6 km) at 84% efficiency.
Microwave power transmission of tens of kilowatts has been well proven by existing tests at
Goldstone in California (1975) and Grand Bassin on Reunion Island (1997).
More recently, microwave power transmission has been demonstrated, in conjunction with solar
energy capture, between a mountain top in Maui and the island of Hawaii (92 miles away), by a
team under John C. Mankins. Technological challenges in terms of array layout, single radiation
element design, and overall efficiency, as well as the associated theoretical limits are presently a
subject of research, as it is demonstrated by the Special Session on "Analysis of Electromagnetic
Wireless Systems for Solar Power Transmission" to be held in the 2010 IEEE Symposium on
Antennas and Propagation. In 2013, a useful overview was published, covering technologies and
issues associated with microwave power transmission from space to ground. It includes an
introduction to SPS, current research and future prospects. Moreover, a review of current
methodologies and technologies for the design of antenna arrays for microwave power transmission
appeared in the Proceedings of the IEEE.
Laser power beaming
Laser power beaming was envisioned by some at NASA as a stepping stone to further
industrialization of space. In the 1980s, researchers at NASA worked on the potential use of lasers
for space-to-space power beaming, focusing primarily on the development of a solar-powered laser.
In 1989 it was suggested that power could also be usefully beamed by laser from Earth to space. In
1991 the SELENE project (SpacE Laser ENErgy) had begun, which included the study of laser
power beaming for supplying power to a lunar base. The SELENE program was a two-year research
effort, but the cost of taking the concept to operational status was too high, and the official project
ended in 1993 before reaching a space-based demonstration.
In 1988 the use of an Earth-based laser to power an electric thruster for space propulsion was
proposed by Grant Logan, with technical details worked out in 1989. He proposed using diamond
solar cells operating at 600 degrees to convert ultraviolet laser light.
Orbital location
The main advantage of locating a space power station in geostationary orbit is that the antenna
geometry stays constant, and so keeping the antennas lined up is simpler. Another advantage is
that nearly continuous power transmission is immediately available as soon as the first space power
station is placed in orbit; other space-based power stations have much longer start-up times before
they are producing nearly continuous power. A collection of LEO (Low Earth Orbit) space power
stations has been proposed as a precursor to GEO (Geostationary Orbit) space-based solar power.
Earth-based receiver
The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes.
Microwave broadcasts from the satellite would be received in the dipoles with about 85%
efficiency. With a conventional microwave antenna, the reception efficiency is better, but its cost
and complexity are also considerably greater. Rectennas would likely be several kilometers across.
In space applications
A laser SBSP could also power a base or vehicles on the surface of the Moon or Mars, saving on
mass costs to land the power source. A spacecraft or another satellite could also be powered by the
same means. In a 2012 report presented to NASA on Space Solar Power, the author mentions
another potential use for the technology behind Space Solar Power could be for Solar Electric
Propulsion Systems that could be used for interplanetary human exploration missions.
Timeline
In the 20th century
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1941: Isaac Asimov published the science fiction short story "Reason," in which a space
station transmits energy collected from the sun to various planets using microwave beams.
1968: Dr. Peter Glaser introduces the concept of a "solar power satellite" system with
square miles of solar collectors in high geosynchronous orbit for collection and conversion
of sun's energy into a microwave beam to transmit usable energy to large receiving antennas
(rectennas) on Earth for distribution.
1973: Dr. Peter Glaser is granted United States patent number 3,781,647 for his method
of transmitting power over long distances using microwaves from a large (one square
kilometer) antenna on the satellite to a much larger one on the ground, now known as a
rectenna.
1978–81: The United States Department of Energy and NASA examine the solar power
satellite (SPS) concept extensively, publishing design and feasibility studies.
1982: Boeing proposal
1987: Stationary High Altitude Relay Platform a Canadian experiment
1994: The United States Air Force conducts the Advanced Photovoltaic Experiment using
a satellite launched into low Earth orbit by a Pegasus rocket.
1995–97: NASA conducts a "Fresh Look" study of space solar power (SSP) concepts and
technologies.
1998: The Space Solar Power Concept Definition Study (CDS) identifies credible,
commercially viable SSP concepts, while pointing out technical and programmatic risks.
1998: Japan's space agency begins developing a Space Solar Power System (SSPS), a
program that continues to the present day.
1999: NASA's Space Solar Power Exploratory Research and Technology program (SERT,
see below) begins.
2000: John Mankins of NASA testifies in the U.S. House of Representatives, saying
"Large-scale SSP is a very complex integrated system of systems that requires numerous
significant advances in current technology and capabilities. A technology roadmap has been
developed that lays out potential paths for achieving all needed advances — albeit over
several decades.
In the 21st century
2001: Dr. Neville Marzwell of NASA states, "We now have the technology to convert the sun's
energy at the rate of 42 to 56 percent... We have made tremendous progress. ...If you can
concentrate the sun's rays through the use of large mirrors or lenses you get more for your money
because most of the cost is in the PV arrays... There is a risk element but you can reduce it... You
can put these small receivers in the desert or in the mountains away from populated areas. ...We
believe that in 15 to 25 years we can lower that cost to 7 to 10 cents per kilowatt hour. ...We offer
an advantage. You don't need cables, pipes, gas or copper wires. We can send it to you like a cell
phone call—where you want it and when you want it, in real time."
2001: NASDA (One of Japan's national space agencies before it became part of JAXA) announces
plans to perform additional research and prototyping by launching an experimental satellite with
10 kilowatts and 1 megawatt of power.
2003: ESA studies
2007: The US Pentagon's National Security Space Office (NSSO) issues a report on October 10,
2007 stating they intend to collect solar energy from space for use on Earth to help the United
States' ongoing relationship with the Middle East and the battle for oil. A demo plant could cost
$10 billion, produce 10 megawatts, and become operational in 10 years. The International Space
Station may be the first test ground for this new idea, even though it is in a low-earth orbit.
2007: In May 2007 a workshop is held at the US Massachusetts Institute of Technology (MIT)
to review the current state of the SBSP market and technology.
2009: Several companies announce future SBSP partnerships and commitments, including Pacific
Gas and Electric (PG&E) & Solaren, Mitsubishi Electric Corp. & IHI Corporation, Space Energy,
Inc., and Japan Aerospace Exploration Agency.
2010: Europe's EADS Astrium announces SBSP plans.
2010: Professors Andrea Massa and Giorgio Franceschetti announce a special session on the
"Analysis of Electromagnetic Wireless Systems for Solar Power Transmission" at the 2010 Institute
of Electrical and Electronics Engineers International Symposium on Antennas and Propagation.
2010: The Indian Space Research Organisation and US' National Space Society launched a joint
forum to enhance partnership in harnessing solar energy through space-based solar collectors.
Called the Kalam-NSS Initiative after the former Indian President Dr APJ Abdul Kalam, the forum
will lay the groundwork for the space-based solar power program which could see other countries
joining in as well.
2010: The National Forensics League announces the resolution for the 2011–2012 debate season
to be substantial space exploration and/or development. Space Based Solar Power becomes one of
the most popular affirmative arguments.
2010: Sky's No Limit: Space-Based solar power, the next major step in the Indo-US strategic
partnership? written by USAF Lt Col Peter Garretson was published at the Institute for Defence
Studies and Analysis.
2012: China proposed joint development between India and China towards developing a solar
power satellite, during a visit by former Indian President Dr APJ Abdul Kalam.
2015: JAXA announced on 12 March 2015 that they wirelessly beamed 1.8 kilowatts 50 meters
to a small receiver by converting electricity to microwaves and then back to electricity.
2015: China Academy of Space Technology (CAST) team won the International SunSat Design
Competition with their Multi-Rotary Joint Design video.
2016: A paper "Lunar-Based Self-Replicating Solar Factory" by Justin Lewis-Webber received
national attention for its innovative approach.
2016: Lt Gen. Zhang Yulin, deputy chief of the [PLA] armament development department of the
Central Military Commission, suggested that China would next begin to exploit Earth-Moon space
for industrial development. The goal would be the construction of space-based solar power
satellites that would beam energy back to Earth.
2016: A team with membership from the Naval Research Laboratory (NRL), Defense Advanced
Projects Agency (DARPA), Air Force Air University, Joint Staff Logistics (J-4), Department of
State, Makins Aerospace and Northrop Grumman won the Secretary of Defense (SECDEF) /
Secretary of State (SECSTATE) / USAID Director's agency-wide D3 (Diplomacy, Development,
Defense) Innovation Challenge with a proposal that the US must lead in space solar power. The
proposal was followed by a vision video
2016: Citizens for Space-Based Solar Power has transformed the D3 proposal into active petitions
on the White House Website "America Must Lead the Transition to Space-Based Energy"and
Change.org "USA Must Lead the Transition to Space-Based Energy" along with the following
video.
2016: Mike Snead proposes legislation to jumpstart Space Solar Power as a capstone to a 4-part
series.
2016: Keith Henson publishes a video on a beam-powered propulsion boostrapping approach to
high volume SBSP. (This is the latest evolution of previous work where he explored laser power
beaming, construction video of a novel thermal solar power satellite design.
3. Non-rocket spacelaunch
Non-rocket spacelaunch refers to concepts for launch into space where some or all of the needed
speed and altitude are provided by something other than expendable rockets. A number of
alternatives to expendable rockets have been proposed. In some systems such as skyhook, rocket
sled launch, rockoon and air launch, a rocket would be used to reach orbit, but would only be part
of the system. Present-day launch costs are very high – $2,500 to $15,000 per kilogram from Earth
to low Earth orbit (LEO). As a result, launch costs are a large percentage of the cost of all space
endeavors. If launch costs can be made cheaper the total cost of space missions will be reduced.
Fortunately, due to the exponential nature of the rocket equation, providing even a small amount
of the velocity to LEO by other means has the potential of greatly reducing the cost of getting to
orbit.
Getting launch costs down into the hundreds of dollars per kilogram range would make many of
the proposed large-scale space projects such as space colonization, space-based solar power and
terraforming Mars possible.
Comparison
Comparison
of
space
Initial operating condition for new systems
Method(a)
Publicat
ion year
Estima
ted
build
cost
GUS$ (b
Payload
mass
kg
1903
Space elevator
1895
Non-rotating
Skyhook
1990
<1
Hypersonic
Skyhook
1993
< 1(c)
Rotovator
1977
Estimate
d
cost
to LEO
US$/kg (b
)
)
Expendable
rocket
launch
methods
Capac
ity
Metri
c tons
per
year
700 – 130, 4,000 – 20,
≈ 200
000
000
Technol
ogy
readines
s level
9
2
2
1,500(d)
30(e)
2
2
Comparison
of
space
Initial operating condition for new systems
Method(a)
Publicat
ion year
Estima
ted
build
cost
GUS$ (b
Payload
mass
kg
launch
Estimate
d
cost
to LEO
US$/kg (b
)
)
Hypersonic
Airplane Space
Tether Orbital 2000
Launch(HAST
OL)
methods
Capac
ity
Metri
c tons
per
year
15,000(f)
Technol
ogy
readines
s level
2
Orbital ring
1980
15
2*1011
< 0.05
4*1010
2
Launch
loop (small)
1985
10
5,000
300
40,000
2+
Launch
loop (large)
1985
30
5,000
3
6,000,00
2+
0
KITE
Launcher
2005
StarTram
2001
Ram
accelerator
2004
Space gun
1865
2
20(g)
0.5
Slingatron
35,000
450
43
2
< 500
6
500
6
100
2 to 4
Laser
propulsion
2
100
550
Microwave
propulsion
1
< 100
600
Orbital Airship
150,000
3000
Up to 4
(a) References in this column apply to entire row unless specifically replaced.
(b) All monetary values in un-inflated dollars based on ref. publication date except as noted.
(c) CY2008 estimate from description in 1993 reference system.
(d) Requires first stage to ~ 5 km/s.
(e) Subject to very rapid increase via bootstrapping.
(f) Requires Boeing proposed DF-9 vehicle first stage to ~ 4 km/s.
(g) Based on Gen-1 reference design, 2010 version.
(h) Jules Vernes novel From the Earth to the Moon. Newton's cannonball in the 1728 book A
Treatise of the System of the World was considered a thought experiment.
Static structures
A space tower is a tower that would reach outer space. To avoid an immediate need for a vehicle
launched at orbital velocity to raise its perigee, a tower would have to extend above the edge of
space (above the 100 km Kármán line), but a far lower tower height could reduce atmospheric drag
losses during ascent. If the tower went all the way to geosynchronous orbit at approximately 36,000
km, or 22,369 miles, objects released at such height could then drift away with minimal power
and would be in a circular orbit. The concept of a structure reaching to geosynchronous orbit was
first conceived by Konstantin Tsiolkovsky. The original concept envisioned by Tsiolkovsky was a
compression structure. Building a compression structure from the ground up proved an unrealistic
task as there was no material in existence with enough compressive strength to support its own
weight under such conditions. Other ideas use very tall compressive towers to reduce the demands
on launch vehicles. The vehicle is "elevated" up the tower, which may extend above the atmosphere
and is launched from the top. Such a tall tower to access near-space altitudes of 20 km (12 mi) has
been proposed by various researchers. The height is limited by materials, with higher structures
possible if the structure tapers (i.e. the upper parts are narrower than the bottom), but with current
construction techniques, cost increases exponentially with construction height. Buckling may be a
failure mode before exceeding a material's nominal compressive yield strength (though designs
such as with a truss may help compensate), but, aside from that and aside from design against
weather, the theoretical scale height of a structure is the allowable load of its material divided by
the product of density and local gravitational acceleration, where needed material cross-section
increases by a factor of e (2.718...) over each scale height.
For common plain carbon steel under a typical allowable stress limit, its scale height is ≈ 1.635
kilometer. A 4.9-kilometer-high tower (3 × its scale height) of such would accordingly mass at least
20 times the weight supported at its top (as e3 ≈ 20). In contrast, an example of a more expensive
high-performance aerospace material, Amoco T300/ERL1906 carbon composite, has a scale height
of 54 kilometers at a safety factor of 2, though construction challenges, including wind loading,
would apply. Earth's atmosphere has approximately 50% of its mass under 6 kilometers elevation,
90% below 16 kilometers, and 99% below 30 kilometers of altitude. Natural mountains reach up
to 9 km altitude. As of 2013, the tallest man-made structure is the Burj Khalifa, which is 829.8 m
tall. A tower or other high-altitude facility could form one component of a launch system, such as
being the base station of a space elevator, or a support pillar for the distal part of a mass driver or
the "gun barrel" of a space gun.
Tensile structures
Tensile structures for non-rocket spacelaunch are proposals to use long, very strong cables (known
as tethers) to lift a payload into space. Tethers can also be used for changing orbit once in space.
Orbital tethers can be tidally locked (skyhook) or rotating (rotovators). They can be designed (in
theory) to pick up the payload when the payload is stationary or when the payload is hypersonic
(has a high but not orbital velocity). Endo-atmospheric tethers can be used to transfer kinetics
(energy and momentum) between large conventional aircraft (subsonic or low supersonic) or other
motive force and smaller aerodynamic vehicles, propelling them to hypersonic velocities without
exotic propulsion systems.
Skyhook
A skyhook is a theoretical class of orbiting tether propulsion intended to lift payloads to high
altitudes and speeds. Proposals for skyhooks include designs that employ tethers spinning at
hypersonic speed for catching high speed payloads or high altitude aircraft and placing them in
orbit.
Space elevator
A space elevator is a proposed type of space transportation system. Its main component is a ribbonlike cable (also called a tether) anchored to the surface and extending into space above the level of
geosynchronous orbit. As the planet rotates, the centrifugal force at the upper end of the tether
counteracts gravity, and keeps the cable taut. Vehicles can then climb the tether and reach orbit
without the use of rocket propulsion.
Such a cable could be made out of any material able to support itself under tension by tapering the
cable's diameter sufficiently quickly as it approached the Earth's surface. On Earth, with its
relatively strong gravity, current technology is not capable of manufacturing tether materials that
are sufficiently strong and light. With conventional materials, the taper ratio would need to be very
large, escalating the total launch mass to a very large degree, and making conventional materials
fiscally infeasible. However, recent concepts for a space elevator are notable for their plans to use
carbon nanotube or boron nitride nanotube based materials as the tensile element in the tether
design. The measured strengths of those nanotube molecules are high compared to their linear
densities. They hold promise as materials to make an Earth-based space elevator possible.
Landis and Cafarelli suggested that a tension structure ("space elevator") extending downward
from geosynchronous orbit could be combined with the compression structure ("Tsiolkovski
tower") extending upward from the surface, forming the combined structure reaching
geosynchronous orbit from the surface, and having structural advantages over either one
individually.
The space elevator concept is also applicable to other planets and celestial bodies. For locations in
the Solar System with weaker gravity than Earth's (such as the Moon or Mars), the strength-todensity requirements aren't as great for tether materials. Currently available materials (such as
Kevlar) are strong and light enough that they could be used as the tether material for elevators
there.
Endo-atmospheric tethers
An endo-atmospheric tether uses the long cable within the atmosphere to provide some or all of
the velocity needed to reach orbit. The tether is used to transfer kinetics (energy and momentum)
from a massive, slow end (typically a large subsonic or low supersonic aircraft) to a hypersonic end
through aerodynamics or centripetal action. The Kinetics Interchange TEther (KITE) Launcher is
one proposed endo-atmospheric tether.
Dynamic structures
Space fountain
A space fountain is a proposed form of space elevator that does not require the structure to be in
geosynchronous orbit, and does not rely on tensile strength for support. In contrast to the original
space elevator design (a tethered satellite), a space fountain is a tremendously tall tower extending
up from the ground. Since such a tall tower could not support its own weight using traditional
materials, massive pellets are projected upward from the bottom of the tower and redirected back
down once they reach the top, so that the force of redirection holds the top of the tower aloft.
Orbital ring
An orbital ring is a concept for a space elevator that consists of a ring in low Earth orbit that rotates
at slightly above orbital speed, and has fixed tethers hanging down to the ground.
The first design of an orbital ring offered by A. Yunitsky in 1982.
In the 1982 Paul Birch JBIS design of an orbital ring system, a rotating cable is placed in a low
Earth orbit, rotating at slightly faster than orbital speed. Not in orbit, but riding on this ring,
supported electromagnetically on superconducting magnets, are ring stations that stay in one place
above some designated point on Earth. Hanging down from these ring stations are short space
elevators made from cables with high tensile strength to mass ratio. Birch claimed that the ring
stations, in addition to holding the tether, could accelerate the orbital ring eastwards, causing it to
precess around Earth. If it were possible to make the precession rate large enough – once per day,
the rate of rotation of the Earth – the ring would be "geostationary" without having to be at the
normal geostationary altitude or even in the equatorial plane.
Launch loop
A launch loop or Lofstrom loop is a design for a belt-based maglev orbital launch system that would
be around 2000 km long and maintained at an altitude of up to 80 km (50 mi). Vehicles weighing
5 metric tons would be electromagnetically accelerated on top of the cable which forms an
acceleration track, from which they would be projected into Earth orbit or even beyond. The
structure would constantly need around 200 MW of power to keep it in place. The system is
designed to be suitable for launching humans for space tourism, space exploration and space
colonization with a maximum of 3 g acceleration. Some other Launch Loops are developed in.
Pneumatic freestanding tower
One proposed design is a freestanding tower composed of high strength material (e.g. kevlar)
tubular columns inflated with a low density gas mix, and with dynamic stabilization systems
including gyroscopes and "pressure balancing".[38] Suggested benefits in contrast to other space
elevator designs include avoiding working with the great lengths of structure involved in some
other designs, construction from the ground instead of orbit, and functional access to the entire
range of altitudes within the design's practical reach. The design presented is "at 5 km altitude and
extending to 20 km above sea level", and the authors suggest that "the approach may be further
scaled to provide direct access to altitudes above 200 km".
A major difficulty of such a tower is buckling since it is a long slender construction.
Projectile launchers
With any of these projectile launchers, the launcher gives a high velocity at, or near, ground level.
In order to achieve orbit, the projectile must be given enough extra velocity to punch through the
atmosphere, unless it includes an additional propulsion system (such as a rocket). Also, the
projectile needs either an internal or external means to perform orbital insertion. The designs below
fall into three categories, electrically driven, chemically driven, and mechanically driven.
Electromagnetic acceleration
Electrical launch systems include mass drivers, railguns, and coilguns. All of these systems use the
concept of a stationary launch track which uses some form of linear electrical motor to accelerate
a projectile.
Mass driver
A mass driver is basically a very long and mainly horizontally aligned launch track or tunnel for
space launch, curved upwards at the end. The concept was proposed by Arthur C. Clarke in 1950,
and was developed in more detail by Gerard K. O'Neill, working with the Space Studies Institute,
focusing on the use of a mass driver for launching material from the Moon.
A mass driver uses some sort of repulsion to keep a payload separated from the track or walls. Then
it uses a linear motor (an alternating-current motor such as in a coil gun, or a homopolar motor as
in a railgun) to accelerate the payload to high speeds. After leaving the launch track, the payload
would be at its launch velocity.
StarTram
StarTram is a proposal to launch vehicles directly to space by accelerating them with a mass driver.
Vehicles would float by maglev repulsion between superconductive magnets on the vehicle and the
aluminum tunnel walls while they were accelerated by AC magnetic drive from aluminum coils.
The power required would probably be provided by superconductive energy storage units
distributed along the tunnel. Vehicles could coast up to low or even geosynchronous orbital height;
then a small rocket motor burn would be required to circularize the orbit.
Cargo-only Generation 1 systems would accelerate at 10-20 Gs and exit from a mountain top.
While not suitable for passengers, they could put cargo into orbit for $40 per kilogram, 100 times
cheaper than rockets.
Passenger-capable Generation 2 systems would accelerate for a much longer distance at 2 Gs. The
vehicles would enter the atmosphere at an altitude of 20 km from an evacuated tunnel restrained
by Kevlar tethers and supported by magnetic repulsion between superconducting cables in the
tunnel and on the ground. For both Gen 1-2 systems, the mouth of the tube would be open during
vehicle acceleration, with air kept out by magnetohydrodynamic pumping.
Chemical
Space gun
A space gun is a proposed method of launching an object into outer space using a large gun, or
cannon. Science fiction writer Jules Verne proposed such a launch method in From the Earth to
the Moon, and in 1902 a movie, A Trip to the Moon, was adapted.
However, even with a "gun barrel" through both the Earth's crust and troposphere, the g-forces
required to generate escape velocity would still be more than what a human tolerates. Therefore,
the space gun would be restricted to freight and ruggedized satellites. Also, the projectile needs
either an internal or external means to stabilize on orbit.
Gun launch concepts do not always use combustion. In pneumatic launch systems, a projectile is
accelerated in a long tube by air pressure, produced by ground-based turbines or other means. In
a light-gas gun, the pressurant is a gas of light molecular weight, to maximize the speed of sound
in the gas. In the 1990s, John Hunter of Quicklaunch proposed use of a 'Hydrogen Gun' to launch
unmanned payloads to orbit for less than the regular launch costs.
Ram accelerator
A ram accelerator also uses chemical energy like the space gun but it is entirely different in that it
relies on a jet-engine-like propulsion cycle utilizing ramjet and/or scramjet combustion processes
to accelerate the projectile to extremely high speeds.
It is a long tube filled with a mixture of combustible gases with a frangible diaphragm at either end
to contain the gases. The projectile, which is shaped like a ram jet core, is fired by another means
(e.g., a space gun, discussed above) supersonically through the first diaphragm into the end of the
tube. It then burns the gases as fuel, accelerating down the tube under jet propulsion. Other physics
come into play at higher velocities.
Blast wave accelerator
A blast wave accelerator is similar to a space gun but it differs in that rings of explosive along the
length of the barrel are detonated in sequence to keep the accelerations high. Also, rather than just
relying on the pressure behind the projectile, the blast wave accelerator specifically times the
explosions to squeeze on a tail cone on the projectile, as one might shoot a pumpkin seed by
squeezing the tapered end.
Mechanical
Slingatron
In a slingatron, projectiles are accelerated along a rigid tube or track that typically has circular or
spiral turns, or combinations of these geometries in two or three dimensions. A projectile is
accelerated in the curved tube by propelling the entire tube in a small-amplitude circular motion
of constant or increasing frequency without changing the orientation of the tube, i.e. the entire
tube gyrates but does not spin. An everyday example of this motion is stirring a beverage by holding
the container and moving it in small horizontal circles, causing the contents to spin, without
spinning the container itself.
This gyration continually displaces the tube with a component along the direction of the
centripetal force acting on the projectile, so that work is continually done on the projectile as it
advances through the machine. The centripetal force experienced by the projectile is the
accelerating force, and is proportional to the projectile mass.
Air launch
In air launch, a carrier aircraft carries the space vehicle to high altitude and speed before release.
This technique was used on the suborbital X-15 and SpaceshipOne vehicles, and for the Pegasus
orbital launch vehicle.
The main disadvantages are that the carrier aircraft tends to be quite large, and separation within
the airflow at supersonic speeds has never been demonstrated, thus the boost given is relatively
modest.
Spaceplanes
A spaceplane is an aircraft designed to pass the edge of space. It combines some features of an
aircraft with some of a spacecraft. Typically, it takes the form of a spacecraft equipped with
aerodynamic surfaces, one or more rocket engines, and sometimes additional airbreathing
propulsion as well.
Early spaceplanes were used to explore hypersonic flight (e.g. X-15). Some air-breathing enginebased designs (cf X-30) such as aircraft based on scramjets or pulse detonation engines could
potentially achieve orbital velocity or go some useful way to doing so; however, these designs still
must perform a final rocket burn at their apogee to circularize their trajectory to avoid returning
to the atmosphere. Other, reusable turbojet-like designs like Skylon which uses precooled jet
engines up to Mach 5.5 before employing rockets to enter orbit appears to have a mass budget that
permits a larger payload than pure rockets while achieving it in a single stage.
Laser propulsion
Laser propulsion is a form of beam-powered propulsion where the energy source is a remote laser
system which can be ground-based, airborne, orbital, or a combination of these. While climbing
out of the atmosphere, the surrounding air can provide the reaction mass. This form of propulsion
differs from a conventional chemical rocket where both energy and reaction mass come from the
solid or liquid propellants carried on board the vehicle.
The concept of laser propelled vehicles was introduced by Arthur Kantrowitz in 1972.
*******