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Senior Science
HSC Course
Stage 6
Space science
Part 4: Rockets and shuttles
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Number: 43172
Title: Space science
This publication is copyright New South Wales Department of Education and Training (DET), however it may contain
material from other sources which is not owned by DET. We would like to acknowledge the following people and
organisations whose material has been used:
Photograph of a lunar landing module courtesy of Rhonda Caddy
Part 4 p 20
Photograph of dish of the Parkes radio telescope © Baska Bartsch, 1997
Part 5 p 14
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Copyright Regulations 1969
WARNING
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pursuant to Part VB of the Copyright Act 1968 (the Act).
The material in this communication may be subject to copyright under the Act.
Any further reproduction or communication of this material by you may be the
subject of copyright protection under the Act.
CLI would also like to thank the following people who have contributed to the development of this resource:
Writer(s):
Steven Vassallo and Jeanette Rothapfel
All reasonable efforts have been made to obtain copyright permissions. All claims will be settled in good faith.
Published by
Centre for Learning Innovation (CLI)
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_______________________________________________________________________________________________
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Copyright of this material is reserved to the Crown in the right of the State of New South Wales. Reproduction or
transmittal in whole, or in part, other than in accordance with provisions of the Copyright Act, is prohibited without the
written authority of the Centre for Learning Innovation (CLI).
© State of New South Wales, Department of Education and Training 2008.
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Contents
Introduction ............................................................................... 2
Going up.................................................................................... 3
What are rockets? ................................................................................3
Rocket stages.......................................................................................6
The space shuttle ...................................................................... 8
Parts of the space shuttle ....................................................................8
Launching the space shuttle ..............................................................11
Experiencing lift-off and re-entry........................................................11
Materials used in the space shuttle ...................................................15
Advantages and disadvantages of the space shuttle program ........17
The changing nature of space flights....................................... 19
Changes up to the present ................................................................19
Changes into the future......................................................................21
Suggested answers................................................................. 25
Exercises – Part 4 ................................................................... 29
Part 4: Rockets and shuttles
1
Introduction
Just think about the amount of effort and energy needed to get rockets
and shuttles up into space. A large booster rocket is required to launch a
spacecraft so that it orbits the Earth.
Compare this with the conditions experienced by a craft re-entering
Earth’s atmosphere. This poses a new set of challenges. The
components and materials used in the construction of rockets and shuttles
must withstand launch and re-entry conditions.
In this part you will be given opportunities to learn to:
•
describe the functions of the components of the Space
Transportation System (STS), commonly called shuttle, including:
–
the orbiter
–
solid rocket boosters (SRB)
–
external tank
•
identify some of the difficulties experienced during lift-off but not
on re-entry into the Earth’s atmosphere
•
explain why a large booster rocket is required during lift-off but not
on re-entry
•
describe properties of materials used in the STS and relate the
properties to conditions experienced during lift-off or re-entry.
You will have opportunities to:
•
gather and process secondary information to trace changes in the
type of systems that have been used in space travel and discuss the
advantages and disadvantages of using a shuttle
•
gather, process and present information from secondary sources on
plans for future space vehicles.
Extracts from Senior Science Stage 6 Syllabus © Board of Studies NSW,
October 2002. The most up-to-date version is to be found at:
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
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Going up
When you throw a basketball in an attempt to shoot a goal, you are
applying a pushing force to make it go up. You assume that gravity will
pull it down.
Going up always requires a force because gravity is constantly pulling
objects down. A plane gets into the air by travelling faster and faster
until the moving air keeps it up. But the air in space is too thin to support
a plane, so a plane cannot travel out of the atmosphere and into space.
Even if a plane could fly high enough, there is no oxygen in space to
burn the fuel for the plane’s engines. Soon it would stop moving and fall
back to Earth. If humans want to go into space, we need specially
designed machines called rockets.
What are rockets?
Rockets are structures containing engines that can give a spacecraft
enough power to lift-off from Earth and still work in space where there is
almost no air. Rockets can work in space because they carry their own
supply of oxygen with them. Sometimes the oxygen is compressed so
that it is liquid; and sometimes it is made from substances called
oxidisers which break down to release oxygen.
Drawing of a Saturn C class rocket, developed during the 1960s by scientists in
the USA. These launch rockets were used in the Apollo lunar landing missions.
Part 4: Rockets and shuttles
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How does a rocket fly?
To picture it easily, think about a flying balloon. (Try it if you like!)
What happens when you blow up a balloon and let it go? Air rushes out
of the balloon and the balloon buzzes around the room. Its forward
motion is caused by the air rushing out the back.
In a liquid rocket engine, the fuel and oxygen are pumped together and
then into the combustion chamber where the mixture is ignited.
tank
containing
oxygen
tank
containing fuel
combustion
chamber
pump
pump
exhaust jet
A rocket design.
The burning fuel in the combustion chamber produces hot gases.
These gases expand to fill a much larger space than the fuel that
produced them so the gases stream out from the tail end of the rocket at
high speed. This causes the force that pushes the rocket forward.
pu
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The force that pushes a rocket forward
(the forward force) is equal to the force
that comes out of the back of it (the
pushing force, or thrust).
For any rocket to launch successfully, its engine thrust must:
•
4
exceed rocket weight so that the rocket can rise from the launch pad
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•
allow easy movement through the thickest part of the atmosphere
•
enable the rocket to reach orbit.
One extra advantage of rocket engines burning fuel is that they lose mass
as they use fuel.
A moving object has a certain amount of momentum.
Momentum = mass ¥ velocity = mv. As mass is lost from a moving
object the velocity increases to maintain the momentum:
mv = mv = mv
A moving object that loses mass maintains its momentum and therefore
its velocity increases.
Rocket engine types
There are two main types of rocket engine – solid and liquid propellant.
Most rockets used in space exploration are liquid propellant as the engine
can be turned on or off. Once a solid engine ignites it cannot be stopped.
liquid
fuel
tank
solid mixture
of fuel and
oxidiser
liquid
oxidiser
tank
hollow core
pumps
combustion
chamber
nozzle
(a) solid propellant
rockets
Part 4: Rockets and shuttles
(b) liquid propellant
rockets
5
Rocket stages
Spacecraft are sent into orbit by a combination of rockets called launch
vehicles. Launch vehicles are made up of parts called stages. There are
usually three stages.
•
The first stage is the bottom and largest rocket. This is used to lift
the spacecraft initially and build up some speed. Once its fuel is
used up, this rocket drops off.
•
Then the second stage fires to gain more speed. It also uses up its
fuel and drops off.
•
The third stage continues firing until the spacecraft reaches the speed
needed to go into orbit. If any course corrections are needed, they are
carried out by small rockets placed at various points on the spacecraft.
Extra booster rockets can be placed alongside the first stage to give extra
thrust at launch time if the spacecraft is heavy.
Saturn V was the largest rocket ever built. It was designed for the
American Apollo missions to the Moon. Here are some facts about the
Saturn V rocket.
Apollo spacecraft
mass approximately 46 000 kg
Third stage
fuel mass 130 000 kg
Second stage
fuel mass 470 000 kg
First stage
fuel mass 2 200 000 kg
The total height of the Saturn V rocket plus spacecraft was 110 metres
while the total mass was 3 000 000 kg. The spacecraft was 25 metres
high. The first stage burnt approximately 15 500 kg of fuel per second.
The second stage burnt approximately 1 000 kg of fuel per second.
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Use this information and the previous diagram as you answer the
following questions. These questions will help you to improve your skills
at calculating.
1
What was the height of the rocket without the spacecraft?
_____________________________________________________
2
Complete the following table. (You will need to calculate the time
to use up fuel from the other data.)
Stage
Mass of fuel
(kg)
Rate of fuel use
(kg per second)
Time to use up fuel
(seconds)
first
second
3
What was the total mass of fuel carried by the three stages?
_____________________________________________________
4
What was the mass of the rocket apart from the fuel?
_____________________________________________________
5
What percentage of the mass of the rocket is fuel?
_____________________________________________________
Please check your calculations now.
Rockets such as the Saturn V and the spacecraft they launched were
disposable. That is, they were only used once.
These single use spacecraft and rockets have been supplemented with
reusable spacecraft, commonly known as space shuttles.
Part 4: Rockets and shuttles
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The space shuttle
The space shuttle is a very versatile, reusable spacecraft. It is sometimes
called the Space Transportation System, or STS. It functions like:
•
a rocket during launch
•
a spacecraft as it orbits Earth
•
a truck as it transports objects to and back from space
•
an unpowered aircraft or glider as it returns to Earth.
Parts of the space shuttle
As you read about the components of the STS below, highlight or underline
the function of each part. Then summarise their functions in the table at the
end of this section.
orbiter
external tank
solid rocket booster
Main parts of the space shuttle (STS).
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The shuttle is approximately 56 metres high and has a total mass of
2 million kilograms when fully assembled. The main components of the
space shuttle are the orbiter, external tank and two rocket boosters.
•
The orbiter can be described as a delta-winged space plane.
The forward section carries the crew and is about the same size as an
interstate commercial passenger jet. In the back of the orbiter is the
cargo bay where the payloads (cargo) are stored. The orbiter uses its
three engines during lift-off taking fuel from the external tank.
Fuel stored in the orbiter is used for brief engine firings in orbit and
before re-entry. The orbiter is designed to re-enter the atmosphere
and land like a glider.
•
The external tank acts like the backbone of the space shuttle.
It contains cryogenic (very cold) liquid hydrogen and liquid oxygen
required for the main engines. In order for the liquid fuel to remain
cold, the tanks are covered with insulating foam. The external tank,
made of lightweight but strong aluminium and titanium alloys, is the
only part of the space shuttle that is not reusable.
•
The two booster rockets provide about 70% of the thrust required to
lift the shuttle and external tank off the Earth.
The solid rocket boosters (SRBs) contain solid propellant,
consisting of:
–
aluminium powder, which is the fuel
–
ammonium perchlorate, which is the oxidiser to provide oxygen
–
iron oxide, which is the catalyst to speed up the release of
oxygen
–
a polymer that binds the above substances together to form a
rubbery consistency.
After separation from the space shuttle, the solid rocket boosters fall to
the ocean with the help of parachutes, where they are recovered to be
refurbished for a later space shuttle mission.
Part 4: Rockets and shuttles
9
Summary of shuttle components
Summarise the functions of the three space shuttle components by
labelling the diagram and completing the table.
Component
Functions
Check your answers.
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Launching the space shuttle
The space shuttle is specially designed so that it can go through lift-off
and re-entry many times. And so that it can carry significant payloads, it
has effective and reusable booster rockets to launch the orbiter
into space.
Boosters take the space shuttle to orbit
The orbiter’s three main engines can lift it but not enough fuel can be
stored in the orbiter for it to reach orbit. Extra fuel must be added by
means of the cryogenic hydrogen and oxygen in the external tank.
The total weight, however, exceeds the thrust capacity of the three
engines. The two solid rocket boosters provide the additional thrust.
The solid rocket boosters can lift their own weight as well as the
combined weight of the orbiter and filled external tank. They are the
most powerful solid fuelled engines ever used.
The solid rocket boosters do not contain enough propellant to enable the
shuttle to reach orbit. Hence the need for the fuel in the external tank as
well as the solid rocket boosters.
Each booster produces nearly 15 million Newtons of thrust at lift-off.
The total thrust provided by the solid rocket boosters and the main
engines exceeds 33 million Newtons. (How big is a Newton? It is about
equal to the weight force of a small apple.)
Experiencing lift-off and re-entry
The space shuttle has been designed to overcome the kind of conditions
experienced during lift-off and re-entry. Although there have been over
100 successful launches of the space shuttle, a launch is extremely
dangerous and anything but routine.
The space shuttle’s external tank alone carries nearly a million kilograms
of explosive hydrogen and oxygen. Essentially, the astronauts are riding
a huge bomb during launch.
Read the next sections that explain the kinds of conditions experienced
during lift-off and re-entry. As you read the information, underline the
difficulties that may be experienced. You’ll use the information in an
activity that follows the information.
Part 4: Rockets and shuttles
11
Conditions during lift-off
Do you know how loud an aircraft is when it takes off? Well, the space
shuttle is much much louder. The gigantic sound produced by the roar of
the engines and the solid rocket boosters can damage the space shuttle if
it bounces off the launch area back up to the shuttle. The noise is about
100 million times louder than normal conversation.
To prevent damage, huge amounts of water are dumped into the flame
trench below the shuttle to absorb this sound. The vast white clouds at
launch are mainly steam from the engines burning the hydrogen and
oxygen fuel as well as steam from the flame trench.
About 60 seconds after lift-off, the space shuttle has accelerated past the
speed of sound. At this time the orbiter engines generate maximum
vibrations. Large aerodynamic forces can damage the shuttle by placing
huge stress on the orbiter’s wings, windshield and tail. Consequently, the
engine thrust must be throttled back from 100% to about 65%.
The ‘throttle back’ also helps to reduce the extent of heating of the
vehicle during launch.
You have already read how the solid rocket boosters are necessary to lift
the huge weight of the space shuttle, due to its required fuel load, off the
ground during launch. The rocket boosters contain a solid fuel which,
when ignited, commits the space shuttle for launch. A huge explosion
would result if it did not lift off at this point. By contrast, the main
engines on the orbiter can be throttled back and even turned off because
they use liquid fuel.
Both solid rocket boosters have nearly burned out after just two minutes.
Then small explosives disintegrate the bolts that hold the boosters to the
external tank. The still thrusting rocket boosters are pushed away from
the space shuttle by tiny rockets at the ends of each booster.
The main engines of the orbiter are cut off about eight and a half minutes
after lift-off. When the external tank has expended its fuel its connecting
bolts are disintegrated by small explosives. As it tumbles downwards
into the atmosphere, it burns up due to heating by friction with the air.
Once the orbiter gets into orbit around Earth, it travels at 8 km/s, or
28 000 km/hr, to maintain orbit. Any slower and it will fall back to
Earth; any faster and it will fly out away from Earth.
The final altitude for orbit for the space shuttle is typically 300 km above
Earth's surface.
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Conditions during re-entry
Re-entry has a different set of problems from those experienced by the
space shuttle during launch. The returning spacecraft falls back to Earth
due to gravity, and 300 km is a long way to fall! The falling shuttle
passes through the atmosphere which produces its own difficulties.
The return from space involves:
•
entering the atmosphere at the correct angle
If the angle is too shallow, the space shuttle will skip off the
atmosphere like a tossed pebble skimming across smooth water.
If it is too great then the space shuttle could burn up or cause very
high ‘g’ forces. Both these could kill the astronauts
•
needing to slow down from hypersonic speeds
The shuttle needs to slow from Mach 26 (26 times greater than the
speed of sound) to subsonic speeds (less than the speed of sound) in
order to land on a small dot on Earth (the landing site)
•
an unpowered descent (no fuel required)
The shuttle simply falls through the atmosphere, approaching the
runway at six times the angle of any passenger jet. There is no
second chance for the gliding orbiter, which lands at a very fast
300 km/hr
•
using the atmosphere as a braking system
This causes super-heating of the outside of the shuttle from the
friction between the atmosphere and the orbiter as it falls
•
a communications blackout
Just when the commander wants to get as much information as
possible about the landing, communication between the shuttle and
Earth becomes difficult.
All communications must be sent via satellites, which redirect
messages between the space shuttle and mission control.
This happens because the intense heat of descent ionises the
surrounding air, changing it to a flashing glow of red, pink and
orange and disrupting direct contact.
Part 4: Rockets and shuttles
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Summary of difficulties of lift-off and re-entry
1
Tabulate difficulties experienced during lift-off and re-entry.
Difficulties during lift-off
2
Difficulties during re-entry
Increased ‘g’ forces are not an issue with launch or re-entry. Forces
of 2 to 3 ‘g’ only are experienced at each time. How is this
possible?
______________________________________________________
______________________________________________________
______________________________________________________
3
Unlike the launch, there is not very much vibration or sound on
re-entry. The orbiter is only just noticeable as it drops below the
speed of sound and reaches the thicker part of the air. Explain why
this is so.
______________________________________________________
______________________________________________________
______________________________________________________
Check all of your answers.
Then do Exercise 4.1.
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Materials used in the space shuttle
The materials used in the space shuttle (STS, or Space Transportation System)
have been chosen or designed to overcome problems that the craft may experience.
Highlight or underline examples as you read about properties of some of the
materials used in the STS. Use the information to complete the summary at the
end of this section.
Materials in the orbiter
The majority of the orbiter’s structure (body) is welded aluminium
covered with an aluminium skin. The wings and tail are made from
honeycombed aluminium panels. Aluminium is used because of its:
•
lightness
•
resistance to corrosion
•
durability
•
strength.
This lightweight construction reduces weight for launch while still
ensuring high strength. The orbiter’s aluminium skin is protected by
surface insulation, which is in the form of:
•
reinforced carbon-carbon fibre
This is used on leading edges, such as the wings and nose cap, as
well as the lower area where the external tank is attached
•
felt blankets
•
about 25 000 tiles
The black and white tiles are made from sand refined into pure silica
fibres, which protect the undersurface of the orbiter.
During the fiery dive of re-entry through Earth’s atmosphere, the orbiter
will experience extreme heating that is sufficient to melt the orbiter’s
aluminium cover. The tiles that protect the orbiter from overheating
during re-entry have a black glass coating for efficient radiation of heat.
Those tiles for lower temperature areas are coated with a white silica
compound to better reflect the heat of the Sun while in orbit.
A tile’s effectiveness at preventing the orbiter’s aluminium structure
from melting is spectacularly shown by heating a tile until it is red hot.
The tile sheds heat so readily that the tile will be cool to the touch in only
a few seconds while its interior is still glowing red. (Don’t try it!)
Part 4: Rockets and shuttles
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Black tiles are used on the upper forward part and around the windows.
Black is a more efficient radiator of heat rays than white. White tiles, a
good reflector of heat rays, are used where the shuttle does not get so hot.
The strong windows of the orbiter are made from a thick glass of
aluminosilicate and fused silica. This glass is designed to withstand
pressure and heat shock while providing crystal clear views and
high efficiency reflection of heat.
Materials in the external tank
The external fuel tank is made of very light but strong aluminium and
titanium alloys. This also ensures the overall lightness of the space
shuttle without compromising strength.
Materials in the solid rocket boosters
The solid rocket boosters are made of stainless steel. This gives the high
strength needed for the launch and for the splash down collision with the
ocean. It also provides heat resistance and ease of refurbishment for the
future reuse of the boosters.
Summary of materials in the space shuttle
Complete the table below to relate materials in the STS with conditions
during lift-off or re-entry. Relate the properties to conditions experienced
during lift-off/re-entry in the third column.
Material in shuttle
Properties of material
Need for material
during lift-off/re-entry
aluminium structure
of orbiter
carbon-carbon fibres on
leading edges and
external tank attachment
black silica tiles on the
orbiter
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white silica tiles on the
orbiter
aluminosilicate and
fused silica windows
aluminium/titanium
alloys in external fuel
tank
stainless steel
booster rockets
Check your answers.
Advantages and disadvantages of
the space shuttle program
The space shuttle is the most capable and most complex vehicle built
since the space program began. It is the first reusable space vehicle and
has been a major means of providing humanity with benefits from space
exploration.
Some uses of the space shuttle include:
•
laboratory research for space, military and commercial use
•
scientific studies including life sciences, materials sciences, combustion
science, solar science, physics, plasma science, behaviour of metals,
study of semiconductors, behaviour of fluid in low gravity conditions,
atmospheric studies, manufacturing of pure crystals for medicines,
study of the growth of cancerous tissue; and the list goes on
•
deployment and repair of satellites, for example, for communication,
Earth observation and astronomy (The interplanetary spacecraft
Galileo sent to Jupiter and the orbiting satellite observatory, the
Hubble Space Telescope were launched from the space shuttle.)
•
transportation of parts required for the construction of an
international space station.
Part 4: Rockets and shuttles
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1
Make your own list of advantages of using the space shuttle for travel to
and from space.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
2
What are some disadvantages of using the space shuttle for travel to and
from space?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
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The changing nature
of space flights
Changes up to the present
The most significant crewed space flights to date have been in the Apollo
program. This United States program involved human exploration of the
Moon in the late 1960s and early 1970s.
In the quest to land humans on the Moon, two spacecraft were launched
on top of the extremely powerful multistage Saturn V rocket.
These spacecraft were:
•
The Apollo spacecraft, which consisted of two parts attached to
each other.
Three astronauts occupied the cone-shaped capsule called the
command module. (See the photograph earlier in this part.)
Attached to the bottom of the command module was a cylindricalshaped service module, which provided electricity, oxygen and other
support functions for the astronauts as well as propelling the rocket
so that it could achieve lunar orbit.
•
The second spacecraft, called the lunar module, was used to provide:
–
a safe landing onto the Moon (the landing gear of this module
was left behind on the Moon’s surface)
a successful launch from the Moon’s surface in the detachable
cabin of the lunar module.
Returning to Earth first required the undocking of the ascent stage of the
lunar module that lifted astronauts from the Moon's surface.
Again, re-entry involved a fiery fall through the atmosphere, slowed by
parachutes to a splashdown in the ocean.
Part 4: Rockets and shuttles
19
A lunar landing module in the Smithsonian museum, Washington
(Photo: by Rhonda Caddy.)
The present day STS evolved from a series of space projects dating
back to the very first space flights with humans on board in the 1960s.
In the 1960s and 1970s improvements in launch vehicles were swift
and dramatic but these spacecraft were not reusable. In 1981, the first
partially reusable launch vehicle, the American space shuttle,
was introduced.
The Russians have used non-reusable, multistage launch vehicles, with
strap-on boosters. These can be used as crewed or uncrewed supply craft
for space stations. The landing module descends through the atmosphere
with the assistance of a heat shield, a parachute and a last minute blast
from rockets situated in the base to cushion the final touchdown.
Look at some of the links for Part 4 of Space Science at www.lmpc.edu.au
then complete Exercise 4.2.
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Changes into the future
There have been no significant changes to the systems required for
people to travel in space since the space shuttle. The reliability of this
ageing technology and the high cost of replacement has seen this system
in use for decades.
However, research continues into the development of new space
transportation systems, to overcome the limitations of present equipment
and to increase the possibilities for space research and exploration.
Planned reusable launch vehicles (RLV)
The space shuttle is known as a first generation reusable launch vehicle
(RLV) even though the external tank is discarded with each mission.
The STS system will only be replaced if new technology is developed
that gives:
•
greater affordable access to space
•
greater reliability and safety
•
a lightweight thermal protection system using composite materials
•
a propulsion material that will reduce weight but improve carrying
capability.
In order for cost-effective launches of space vehicles to occur, single
stage-to-orbit vehicles must be developed. This means that the vehicle
would launch from Earth without a disposable fuel system, orbit in space
and return as the same vehicle that was launched.
The Lockheed Martin X–33 reusable launch vehicle was an unpiloted
vehicle designed for such purposes. The project aimed at reducing the
cost of launching cargo into orbit from $US25 000 per kilogram to
$US2 500 per kilogram in the year 2000 dollars. This transport system
was expected to fly every two weeks rather than only a couple of times
each year.
The unpiloted X-34 was another vehicle design. It was an example of a
low cost reusable launch vehicles.
The X-33 and X-34 projects were cancelled in 2001 but the X-37
reusable launch vehicle project continues.
Part 4: Rockets and shuttles
21
X–33
X–37
X–34
RLV designs
Plans for future space vehicles
The cost of research and development to overcome the huge technical
challenges seems to be the delaying factor for the construction of other
reusable launch vehicles. So predicting the future of space transportation
is very difficult.
International designers will be looking at spaceliners that can take off
from an airport, fly into orbit and land at an airport in order to make
flights between continents faster than they are today. At present, large
passenger jets fly at only Mach 1 (travelling at the speed of sound).
Even the Concorde jet travels at only just over Mach 2.
NASA is developing a vehicle with scramjet (supersonic combustion
ramjet) engines but it is not one that will be launched from Earth.
It needs to be launched from another aircraft at high altitude. If an
aircraft with scramjet engines flew overhead like a normal aeroplane, it
would cause windows to break, maybe buildings would be destroyed,
trees would be flattened and human eardrums would be ruptured.
A ramjet has no moving parts. Air rams into the engine as a result of
prior movement of the engine through the air, fuel is injected and the hot
expanding gases force the engine forward.
A scramjet is a Supersonic Combustion ramjet. The air into which the
fuel, normally hydrogen gas, is injected is moving at supersonic speeds.
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A diagram of the NASA X-43c scramjet is shown below:
In 2002 a test carried out by a University of Queensland team demonstrated
that they had developed the most advanced form of scramjet engine.
Find out more about their design and its testing at Woomera rocket range in
South Australia at http://www.lmpc.edu.au/Science.
Make a summary about plans for future space vehicles using the information
provided in this section. Look for additional information in other sources,
such as the Internet. Complete Exercise 4.3.
Part 4: Rockets and shuttles
23
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Suggested answers
Rocket stages
1
85 m (110 – 25 = 85 m)
2
The completed table is below. To find the time (in the last column),
you needed to divide the mass of fuel by the rate at which it was
used.
Stage
first
second
Mass of fuel
(kg)
Rate of fuel use
(kg per second)
Time to use up fuel
(seconds)
2 200 000
15 500
142
470 000
1 000
470
3
2 800 000 kg (2 200 000 + 470 000 + 130 000 = 2 800 000 kg)
4
200 000 kg (3 000 000 – 2 800 000 = 200 000 kg)
5
93%
Part 4: Rockets and shuttles
( 2800000 ¥ 100 = 93% )
3000000
1
25
Summary of shuttle components
Check your diagram labels against the labels on the page 9 diagram.
Component
Functions
orbiter
craft that goes into orbit; carries
payload and crew; returns to Earth
external tank
carries fuel for journey after lift-off;
acts as backbone for shuttle during
launch
solid rocket boosters (SRB)
provide extra energy to lift the shuttle
from Earth; fall back after launch to be
reused
Summary of difficulties of lift-off and re-entry
1
Here is an example of a completed table.
Difficulties during lift-off
Difficulties during re-entry
•
engine vibration can damage
space shuttle
•
must enter Earth’s atmosphere
at the correct angle
•
the need to get a large enough
force to lift the STS up away
from Earth
•
the orbiter has to slow from its
orbit speed
•
•
forces to lift the STS can cause
damage to the orbiter
there is only one chance of
landing because the orbiter falls
and glides
•
fuel for the STS is explosive
•
•
the launch cannot be cancelled
once the booster rockets are
fired, no matter what problems
occur
the orbiter is heated by friction
with the atmosphere as it falls
•
communication is difficult
during re-entry
•
2
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the orbiter must speed up to
reach and maintain the correct
orbit speed
The lift-off and re-entry speeds are controlled so that the astronauts
are not subjected to high ‘g’ forces. Larger forces would occur if all
the rockets fired together at full-throttle after lift-off or if the orbiter
landed at a faster speed. Larger forces could crush the astronauts.
Space science
Gill Sans Bold
3
Sound is passed through the air by vibrating air particles. There are
hardly any air particles to vibrate until the orbiter reaches the thicker
part of the atmosphere. Because the orbiter is travelling so quickly,
this happens very close to landing time.
Summary of materials in the space shuttle
Here is an example of a completed table.
Material in shuttle
Properties of material
Need for material
during lift-off/re-entry
aluminium structure
of orbiter
light; strong; durable;
corrosion resistant
light so it can lift off;
strong to withstand
forces of lift-off and
re-entry; durable and
corrosion resistant for
reusability
carbon-carbon fibres on
leading edges and
external tank attachment
strong; insulating
protect edges of wings
and nose cap; give
strong attachment of
external tank
black silica tiles on the
orbiter
radiate heat; insulating
shed heat during launch,
orbit and particularly, on
re-entry
white silica tiles on the
orbiter
reflect heat; insulating
reflect heat during
launch and orbit
aluminosilicate and
fused silica windows
strong; heat and
pressure resistant;
transparent
provide visibility during
mission and particularly,
for re-entry and landing
aluminium/titanium
alloys in external fuel
tank
light; strong
light for lift-off; strong to
provide rigidity for entire
STS during launch
stainless steel in
booster rockets
strong; heat resistant;
easy to reuse
operate during high
forces of lift-off; fall back
to Earth without burning
or bending
Part 4: Rockets and shuttles
27
Advantages and disadvantages of the space shuttle
program
28
1
Advantages of the STS include that it: is reusable; gives convenient
access to a wide range of experiments in space; enables deployment
and repair of satellites; is used as a transport vehicle for building a
station in space.
2
Disadvantages of the STS include that it: is costly; is dangerous for
astronauts (and potentially for others if debris falls to Earth);
produces reliance on the USA for space exploration and research.
Space science
Gill Sans Bold
Exercises – Part 4
Exercises 4.1 to 4.3
Name: _________________________________
Exercise 4.1
a)
Label the parts of the STS with their functions.
b)Using the space shuttle as an example, explain why a large booster
rocket is required during lift-off but not on re-entry.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Part 4: Rockets and shuttles
29
c)
Identify some of the difficulties experienced during lift-off but not
on re-entry.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Exercise 4.2
List changes in the types of systems that have been used in space travel.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Exercise 4.3
Outline plans for future space vehicles. Include information about future
RLVs and how these spacecraft could be different from the STS.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
30
Space science