The Pioneer Program: The History and Legacy of NASA’s Unmanned Space Missions to the Outer Solar System

Space exploration was always an expensive business, and throughout NASA’s history, the agency has had to justify to Congress its need for every dollar it intended to spend. This problem has helped NASA to be more careful and more creative with the money they did receive, and scientists had to justify the equipment they wanted to include on each space probe. They had to justify the size and the power demand, too. If they wanted too much, the entire mission might be scrubbed, and all their work would have been for naught. This made planning and designs leaner and more efficient, as scientists and engineers were more careful with their recommendations.

At the same time, scientists have been repeatedly surprised by their discoveries. Some of those discoveries revealed the dangers of space, like the Van Allen radiation belt, dangerous to astronauts without the right kind of protection. NASA also discovered the massive radiation belt surrounding Jupiter thanks to the Pioneer probes in 1973 and 1974. Similarly, with the knowledge that Titan, the largest moon of Saturn, has a thick atmosphere, later missions were sent to investigate the moon up close. Thus, the Huygens lander pierced the Titan atmosphere in January of 2005 to investigate.

Although Apollo 11’s successful mission to the Moon is seen as the culmination of the Space Race, and the Apollo program remains NASA’s most famous, one of the space agency’s most successful endeavors came a few years later. In fact, the Pioneer program was the most diversified sequence of any of NASA’s programs, and though they’re now remembered for being among the first probes in history to reach the Outer Solar System, the elaborate planning changed goals several times over several years before resulting in historic successes. NASA had wanted to do a Grand Tour of the Solar System toward the end of the 1970s to take advantage.