a
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i
d
n
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– leading the
Sum
way to a brighter future
South Africans had special reason to celebrate World Space
Week from 4 to 10 October this year. On 17 September 2009 our own
SumbandilaSat was launched into orbit 500 km above the Earth,
where it will gather information to keep our nation safe and
prosperous, allowing us to dream of a brighter future.
T
he 81 kg SumbandilaSat, which
means 'lead the way' in Tshivenda,
was launched by the Russian space
agency, Roscosmos. The Department of
Science and Technology led the project
which cost R26 million. SumbandilaSat is
a major milestone in South African space
technology and will have many benefits
for the country.
SumbandilaSat was built by a company
called SunSpace Information Systems
(SSIS) under contract to the University of
Stellenbosch. The Council for Scientific
and Industrial Research's (CSIR) Satellite
Applications Centre at Hartebeesthoek
does the telemetry (remote measurement
and reporting of information), tracking,
control and data capturing of our satellite.
What is a satellite?
A satellite is any object, either man-made
or naturally occurring, that orbits around
something else. For example, the moon
orbits around the Earth and is thus a
satellite. The Earth orbits around the
sun and is a satellite of the sun. Other
examples of naturally occurring satellites
include comets, stars, asteroids
and other planets.
For many years,
man-made satellites
remained a dream
until the technology
(rocket engines,
guidance systems,
and so on) was
developed. Finally, in
1957, the first artificial
satellite, called Sputnik, was
launched by the Russians. It consisted of
little more than a spherical case with a radio
transmitter, but it caused quite a stir. Many
man-made satellites now orbit the Earth.
Education and training
The SumbandilaSat project has already
had important spin-offs in the form of
several educational opportunities at
various levels, from school
learners to post-graduate
university students,
including satellite
engineers at
Stellenbosch
University.
What are satellites How do
used for?
satellites
We currently use many
work?
different types of satellite
to track things like weather, to make our cellphones
work, to find out how to get
somewhere and to gather
more information about the
Earth and about the galaxy.
About 5 000 man-made satellites are now
orbiting the Earth, and on clear, dark nights, it is often
possible to see one in the night sky.
Man-made satellites are classified by type, and there are
more than ten types. Some of the main types of satellites
used today are astronomical satellites, communication
satellites, earth observation satellites, weather satellites
and space stations. Other types of satellite may carry
animals or other life forms such as plants so that research
can be done on earth life forms in space. Navigational
satellites are now popular and form a vital part of the
global positioning system (GPS).
What is SumbandilaSat used for?
South Africa's Sumbandila satellite is an earth observation
satellite. The images it sends back to Earth give a great
deal of information on South Africa's natural environment
to our policy-makers and scientists. SumbandilaSat gives
us up-to-date information so that we can plan and make
decisions. Geospatial information from space is combined
with measurements obtained on the ground in a powerful
way. This lets us find out about the state of crops and make
forecasts about them. The satellite sends other important
information which we need for better food security and
sustainable livelihoods for farmers. Satellites cover the
whole of the Earth so they are very important for studying
climate change and the effects of human activity, such
as ozone depletion or the loss of wetlands.
SumbandilaSat sends information to help authorities
look at coastal activities such as smuggling and illegal
fishing, to help in disaster management, and to monitor
droughts, desertification and agricultural crops. It also
carries experimental equipment, such as communications
for amateur radio and the Department of Communications.
Communication
antennas, radio receivers
and transmitters enable
the satellite to communicate
with ground stations, called
command centres. Messages
sent to the satellite from a ground
station are "uplinked" and messages
transmitted from the satellite to earth
are "downlinked."
Many satellites are battery-powered, and take
advantage of the ultimate battery recharger, the sun.
Silvery solar panels are prominent features on many
satellites. Other satellites have fuel cells that convert
chemical energy to electrical energy, while a few rely
on nuclear energy. Small thrusters control the attitude
and altitude to modify and stabilise the satellite's
position in space. Energy is also needed to provide
climate control onboard for delicate instruments
and sometimes for people.
Specialised systems carry out the tasks assigned to
the satellite. The systems often include sensors that can
photograph a range of wavelengths. Telecommunications
satellites require no optics, while environmental (earth
observation) satellites do. Environmental satellites
transmit data as numbers
to a computer on Earth
Image courtesy NASA.
which translates this
Hurricane Katrina as
digital data into images.
seen by satellite.
World Space Week
Over 50 nations across
the world celebrate World
Space Week and the
contribution space science
and technology makes to
improving human quality
of life each year from
4 - 10 October.
Image courtesy MODIS Land Group, NASA. This true-colour image of
South Africa shows fires in the Western Cape. Satellite images
such as these can help us to fight disasters such as fires.
SM
2
MiniMag
2
World Space Week
October 4 - 10
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