Beginning of Essay
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, the ....

Middle of Essay
.... 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 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 spide ....