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Axion 3D Atlas
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sats
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intro.txt
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1998-01-23
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{bigtext=20,85,"Satellites"}
{4}On any given evening, soon after sunset, you may have witnessed what appears
to be stars crossing the night sky. What we sometimes mistake for falling
stars are actually one of the over 3,500 satellites which orbit around the earth.
A satellite is a human-made spacecraft placed in space to orbit another body.
These space crafts can be crewed, such as the Space Shuttle, or uncrewed, such
as NASA's Hubble Space Telescope. They can be sent into space with the
intention that they will not be recovered, or they can be designed to be
recovered or repaired by Space Shuttle crews.
Satellites may be either active or passive. Passive satellites contain no radio
transmitters or other energy signals, but rather only reflect signals beamed at
them from Earth. Active satellites collect data and emit radio signals that transmit
the information down to Earth.
Satellites are designed to serve one of three general purposes: Space Science,
Applications, or Communications.
{3}Space Science{4} - Studies the Sun, measure magnetic fields or to electromagnetic
spectrum, including gamma rays, X-rays, ultraviolet, visible light, infrared,
microwaves and radio waves.
{3}Application{4} - Survey the Earth's resources and supply weather photographs and
other information to forecasters.
{3}Communications{4} - Relay telephone calls and television signals, transmit scientific
information for other satellites down to Earth, and relay voice communications
between the astronauts orbiting on the Space Shuttle and mission controllers on
Earth.
Data from these satellites help promote an awareness of the environment, the world,
and the universe. The new technologies developed for these satellites have additional
applications that benefit life on Earth.
{2}GLOSSARY OF TERMS:{4}
{3}apogee{4} - farthest point from the Earth
{3}perigee{4} - closest point to the Earth
{3}inclination{4} - angle to the equator
{3}transponder{4} - a device for receiving radio signal and automatically transmitting a
different signal.
{3}orbit{4} - set path in space, satellites are launched into a variety of orbits,
depending on the satellite's purpose
{3}geostationary/geosynchronous orbit{4} - 35,888 kilometers above the equator, at this
height a satellite's velocity matches that of a point on the Earth's equator. Seen
from the earth, the satellite appears to be floating over a certain spot on the equator.
{3}Sunsynchronous orbit{4} - fixed with respect to the sun so that the satellite passes overhead
at the same local time each day.
{3}Polar or near polar orbit{4} - launching at an inclination of approximately 90 degrees to the
equator. These satellites travel in a circular pattern over the North and South Poles so
that they can survey all or a major portion of the Earth as it turns below the.