America’s scientists gave their first satellite the perfect name: Explorer 1. After all, what destination could be more ripe for exploration than outer space? The rocket-based craft's launch from Cape Canaveral, Fla., was tied to the International Geophysical Year, when countries around the world collaborated on all kinds of science projects, both earth- and space-based. The Soviet Union had launched the world’s first satellite, Sputnik I, months earlier, lighting a fire under America’s efforts. The unmanned satellites started a race to put people in space and, ultimately, on the moon; NASA was formed six months after Explorer I was deployed.
Explorer I sent back data for four months, during which time it detected the Van Allen radiation belt that surrounds our planet (James Van Allen was one of the scientists behind the Geophysical Year idea and the push for studying space).
The U.S. has now sent more than 90 Explorer satellites on scientific missions. The first satellite launches were important not only because they helped jump-start space exploration, but because satellites have become a big part of the way we travel today. Our GPS devices, phones and tablets use them to help us figure out where we are and map out where we’re going.