Satellites orbit the earth. Through electronic eyes from hundreds of miles overhead, the satellites lead prospectors to mineral deposits invisible on earth’s surface. Relaying communications at the speed of light, they shrink the planet until its most distant people are only a split second apart.
They beam world weather to our living room TV and guide ships through storms. Swooping low over areas of possible hostility, spies in the sky maintain surveillance that helps keep peace in a volatile world.
How many objects, exactly, are orbiting out there? Today’s count is 4,914. The satellites begin with a launch, which in the U.S. takes place at Cape Canaveral in Florida, NASA’s Wallops Flight Center in Virginia, or, for polar orbiters, Vandenberg Air Force Base in California. A few simply vanish into the immensity of space.
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When a satellite emerges from the rocket’s protective shroud, radioelement regularly reports on its health to round-the-clock crews of ground controllers. They watch over the temperatures and voltages of the craft’s electronic nervous system and other vital ‘organs’, always critical with machines whose sunward side may be 300 degrees hotter than the shaded part.
Once a satellite achieves orbit-that delicate condition in which the pull of earth’s gravity is matched by the outward fling of the crafts speed-subtle pressures make it go astray Solar flares make the satellite go out of orbit. Wisps of outer atmosphere drag its speed. Like strands of spider web, gravity fields of the earth, moon, and sun tug at the orbiting space farer.
Even the sunshine’s soft caress exerts a gentle nudge. Should a satellite begin to wander, ground crews fire small fuel jets that steer it back on course. This is done sparingly, for exhaustion of these gases ends a craft’s useful career. Under such stresses, many satellites last 2 years.
When death is only a second away, controllers may command the craft to jump into a high orbit, so it will move up away from earth, keeping orbital paths from becoming too cluttered. Others become ensnarled in the gravity web; slowly they are drawn into gravitational shat serve as space graveyards.
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A satellite for communications would function like a great antenna tower, hundreds or even thousands of miles above the earth, capable of transmitting messages almost instantaneously across die oceans and continents. Soon after the launch of ATWS-6, (a satellite designed to aid people) NASA ground controllers trained its antenna on Appalachia.