Satellites

Satellites orbit the earth doing our bidding in ways

that enrich the lives of almost all of us. Through

electronic eyes from hundreds of miles overhead,

they lead prospectors to mineral deposits invisble

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

a surveillance that helps keep peace 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 Cape Canaveral in Florida, NASA's Wallops

Flight 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, or

dies in the inferno of a defective rocket blast, or is

thrust into improper orbit. A few simply vanish into

the immensity of space. When a satellite emerges

from the rocket's protective shroud, radiotelemety

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 degress 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 Page 2 ------ 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

spiderweb, gravity feilds of the earth, moon, and

sun tug at the orbiting spacefarer. 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