Echo 1.

Many people have felt that sending astronauts into space has always been an expensive publicity stunt. They require costly equipment, training, and safety measures, yet unmanned satellites have proven just as useful at gathering scientific data. A major breakthrough in the use of unmanned satellites was the launching of Echo 1 on 12 August 1960. Echo 1 was a giant balloon designed by Bell Laboratories and NASA working in partnership. The balloon material was squeezed into a payload and launched into space. Once there, a chemical was used to inflate the balloon, made from a plastic film and covered with an aluminum skin. Echo also had two tiny radio transmitters so it could be tracked. (Actually, as it was large and in a low orbit, it could be seen from Earth). Echo was a "passive" communications satellite. When it was in the right...