This is a cutaway model of Pioneer 4, one of the early satellites designed for lunar exploration. It was equipped with Geiger counters to measure radiation in space. The sister ship of Pioneer 3, it was launched from Cape Canaveral, Florida, on March 3, 1959, atop a Juno II rocket. Pioneer 4 successfully passed within 60,000 kilometers (37,300 miles) of the Moon the day after launch. The satellite was tracked for 82 hours to a distance of 655,000 kilometers (407,000 miles) from Earth, a record at that time. Pioneer 4 is now orbiting the Sun, the first U.S. spacecraft placed in solar orbit.
NASA transferred this model to the Museum in 1975.
Transferred from National Aeronautics and Space Administration and Jet Propulsion Laboratory