Wednesday, February 6, 2019

Satellites :: essays research papers

Satellites orbit the earth doing our bidding in waysthat enrich the lives of closely all of us. Throughelectronic eyes from hundreds of miles overhead,they lead prospectors to mineral deposits invisbleon earths surface. Relaying communications at thespeed of light, they shrink the planet until its most strange people are only a split second apart. They reflect world weather to our living room TV andguide ships by storms. Swooping low overareas of possible hostility, spies in the sky maintaina surveillance that helps keep peace in a volatileworld. How more objects, exaclty, are orbitingout there? Todays count is 4,914. The transmits pop out with a launch, which in the U.S. takes placeat Cape Canaveral in Florida, NASAs WallopsFlight Center in Virginia, or, for polar orbiters,Vandenberg Air Force Base in California. One satellite in 20 is crippled by the jolt of lift-off, ordies in the inferno of a defective rocket blast, or isthrust into inappropriate orbit. A few simply vanish intothe immensity of space. When a satellite emergesfrom the rockets protective shroud, radiotelemetyregularly reports on its health to round-the-clockcrews of ground controllers. They examine over thetemperatures and voltages of the crafts electronicnervous system and other vital " variety meat", alwayscritical with machines whose sunward side whitethorn be300 degress hotter than the shaded part. at once asatellite achieves orbit--that delicate condition inwhich the pull of earths gravitational attraction is matched by theoutward fling of the Page 2 ------ craftsspeed--subtle pressures make it go astray. Solarflares make the satellite go out of orbit. Wisps ofouter airwave drag its speed. Like strands ofspiderweb, gravity feilds of the earth, moon, andsun tug at the orbiting spacefarer. plain thesunshines soft caress exerts a gentle nudge.Should a satellite begin to wander, ground crewsfire small fuel jets that steer it back on course. Thisis done sparingly, for exhaus tion of these gasesends a crafts useful career. Under such stresses,many satellites last 2 years. When death is only asecond away, controllers may command the craftto jump into a high orbit, so it ordain move up awayfrom earth, keeping orbital paths from becoming in any case cluttered. Others become ensnarled in the

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