Explorer 1 was a bullet-shaped satellite about 6.5 feet (2 meters) long and weighing thirty-one pounds (fourteen kilograms). It was designed by the pioneering space scientist James Van Allen (1914–2006) at the University of Iowa, and contained instruments to measure the temperature and density of Earth’s upper atmosphere. It also had a radiation detector that found thick rings of radiation surrounding our planet, which today are called the Van Allen belts. Explorer 1 remained in orbit until 1967, returning valuable scientific data about the nearby reaches of outer space.