There were a total of 13 pioneer spacecraft launched by NASA (National Aeronautics and Space Administration). Although Pioneers 0, 1 and 2 failed to record any significant data, 12 and 13 have been very sucessful by being launched to Venus and have studied the structure and composition of the Venusian atmosphere. The mission also provided the first radar map of the planet's surface.
Pioneers 0, 1 and 2
Pioneer 0,1 and 2 were three of the first spacecraft to be launched in attempt to send data recorded in space back to earth. Each of the three vehicles were designed to go into orbit around the Moon and photograph the Moon's surface. None of the vehicles accomplished their mission, although some useful data was returned.
The first spacecraft, the pioneer 0 was launched bye USFA (United States Air Force). Unfortunatly, 77 seconds after it's launch, pioneer 0 exploded leaving no data collected at all.
Pioneer 1 being given insufficient speed to escape the Earth's gravitational field. Although lunar orbit was not achieved, it did reach an altitude of 113,854 km above Earth and provided data on the extent of the Earth's radiation belts.
Pioneer 2 also suffered a launch vehicle failure and reentered the Earth's atmosphere 6 hours and 52 minutes after launch (it did not return any significant data).
Pioneers 3 and 4
Smaller than the earlier Pioneers, Pioneer 3 and 4 each carried only one
experiment to detect cosmic radiation. Both vehicles were planned to pass the moon and return data about the Earth and Moon's radiation environment. The launch of Pioneer 3 failed when the launch vehicle first's stage cut-off early. Although Pioneer 3 did not achieve escape velocity, it reached an hight of 102,332 km and discovered a second radiation belt around Earth. The launch of Pioneer 4 was successful, and Pioneer 4 was the first American spacecraft to escape Earth's gravitational pull as it passed within 58,983 km of the moon The spacecraft returned data on the Moon radiation environment.