Pioneer 3

Pioneer 3 was a U.S. lunar probe launched on December 6, 1958, by the Army Ballistic Missile Agency (ABMA) from Cape Canaveral, Florida. It was intended to fly by the Moon and enter a heliocentric orbit, providing data on the radiation environment in space. The spacecraft was a cone-shaped probe, similar to its predecessor Pioneer 2, but ultimately failed to reach the Moon due to a premature cutoff of the launch vehicle's first stage.

Although Pioneer 3 did not achieve its primary lunar objective, it did reach a peak altitude of 102,360 kilometers (63,600 miles) and returned valuable data regarding the intensity and distribution of radiation in the Van Allen radiation belts. It also confirmed the existence of an outer radiation belt. The probe transmitted data for approximately 38 hours before its batteries were depleted and communication was lost. Pioneer 3 re-entered the Earth's atmosphere on December 7, 1958.