Golden anniversary--U.S. enters space race

Explorer 1 contained three scientific experiments. Perhaps the most important was the cosmic ray detector, which was actually a Geiger counter. Its findings led to the discovery of the Van Allen radiation belts which circle the Earth. Inside the craft was a microphone, which was included to detect the sound of meteorites hitting Explorer 1. A micrometeor erosion kit was designed to measure the impacts of tiny meteorites. One possibly was detected before the batteries lost power on May 23, 1958. On the ship's nose cone was a temperature probe.

Again, the wires hanging from the middle are the satellite's antennae. Explorer 1 circled the Earth more than 58,000 times before it fell from orbit in 1970.