||In 1958, President Eisenhower gave permission for the U.S. Air Force and the U.S. Army to launch two lunar probes each. These "Pioneer" spacecraft were supposed to make close flybys of the moon, taking pictures and collecting radiation data. The Air Force chose the TRW company to build Pioneer 1 and 2, while the Army chose JPL to build Pioneer 3 and 4. Pioneers 1, 2 and 3 all failed to reach their intended lunar flight paths, or trajectories, due to various launch vehicle problems.
Pioneer 4 was the first success, relatively speaking. The launch vehicle put the spacecraft on a trajectory toward the moon on March 3, 1959, but it wasn't quite the right one. Pioneer 4 passed the Moon at too great a distance, and didn't return any pictures. The mission did, however, give JPL's new deep space navigators valuable experience in tracking space objects.