SatellitesSatellites orbit the earth doing our bidding in ways that enrich the lives ofalmost all of us. Through electronic eyes from hundreds of miles overhead, theylead prospectors to mineral deposits invisble on earth’s surface. Relayingcommunications at the speed of light, they shrink the planet until its mostdistant people are only a split second apart. They beam world weather to ourliving room TV and guide ships through storms. Swooping low over areas ofpossible hostility, spies in the sky maintain a surveillance that helps keeppeace in a volatile world.How many objects, exaclty, are orbiting out there? Today’s count is 4,914.
The satellites begin with a launch, which in the U.S. takes place at CapeCanaveral in Florida, NASA’s Wallops Flight Center in Virginia, or, for polarorbiters, Vandenberg Air Force Base in California.
One satellite in 20 iscrippled by the jolt of lift-off, or dies in the inferno of a defective rocketblast, or is thrust into improper orbit. A few simply vanish into the immensityof space. When a satellite emerges from the rocket’s protective shroud,radiotelemety regularly reports on its health to round-the-clock crews of groundcontrollers. They watch over the temperatures and voltages of the craft’selectronic nervous system and other vital “organs”, always critical withmachines whose sunward side may be 300 degress hotter than the shaded part.Once a satellite achieves orbit–that delicate condition in which the pull ofearth’s gravity is matched by the outward fling of the crafts speed–subtlepressures make it go astray. Solar flares make the satellite go out of orbit.Wisps of outer atmosphere drag its speed.
Like strands of spiderweb, gravityfeilds of the earth, moon, and sun tug at the orbiting spacefarer. Even thesunshine’s soft caress exerts a gentle nudge.Should a satellite begin to wander, ground crews fire small fuel jets that steerit back on course. This is done sparingly, for exhaustion of these gases ends acraft’s useful career.
Under such stresses, many satellites last 2 years. Whendeath is only a second away, controllers may command the craft to jump into ahigh orbit, so it will move up away from earth, keeping orbital paths frombecoming too cluttered. Others become ensnarled in the gravity web; slowly theyare drawn into gravitational that serve as space graveyards.A satellite for communications would really be a great antenna tower, hundredsor even thousands of miles above the earth, capable of transmitting messagesalmost instantaneously across the oceans and continents.Soon after the launch of ATWS-6, “the Teacher in the sky”, (a satellite designedto aid people) NASA ground controllers trained its antenna on Appalachia. Thereis brought evening college classes to schoolteachers whose isolation deniedopportunity for advancement.
The use of Satellites is growing rapidly and so is the different jobs for them.