In the summer of 1958, the United States quietly launched a small satellite that carried a very big secret. Explorer 4 wasn’t just another science mission. It was part of a classified effort to understand what happens when nuclear weapons are detonated in space.
Designed by Dr. James Van Allen’s team and launched aboard a Juno I rocket, Explorer 4 became the first satellite to observe both natural and artificial radiation belts surrounding Earth. It flew during the covert Operation Argus tests, where atomic bombs were exploded high above the atmosphere.
While the public heard little about it at the time, Explorer 4 helped define the dangers and possibilities of space-based warfare. In this episode of Dave Does History, we look back at the mission, the Cold War urgency behind it, and how one tumbling, short-lived satellite changed how we understood space and what we might one day do with it.
