English: In February 1958, the U.S. flew its first satellite, Explorer 1, just four months after the Soviet Union shocked the world with their launch of Sputnik 1. The space race was on. Here they are, spare satellite shells from the respective programs to show the relative size.

While Sputnik was a large sphere with four trailing antenna that proved its presence (with beeps detectable by amateur ham radio operators globally), the smaller and 10x lighter Explorer carried scientific instruments: a cosmic ray detector to measure the radiation levels and micrometeorite impact sensors. We wanted to know how dangerous it was out there for subsequent missions. And we discovered the van Allen belts, a region that saturated the sensors with energetic particles from the million mile-per-hour solar wind. It also had four antenna wires with flexible whips, spin-stabilized in orbit. In 1959, Explorer 6 took the first photo of Earth from space.

I recently acquired this nose cone and payload carrier for the Explorer 1 satellite fabricated and used by JPL and the Army Ballistic Missile Agency (ABMA) Fabrication & Advanced Engineering (F&AE) Laboratory in conjunction with the first successful U.S. orbital satellite program.

Dr. Wernher von Braun is seen holding the payload and forth stage of the Juno rocket developed under his direction (below). JPL designed and built the satellite in just three months, commencing in response to the Sputnik surprise. The satellite used 20 transistors and weighs 18 lbs.