Exploration of Jupiter Exploration of Jupiter The exploration of Jupiter has been conducted via close observations by automated spacecraft. It began with the arrival of "Pioneer 10" into the Jovian system in 1973, and, , has continued with eight further spacecraft missions. All of these missions were undertaken by the National Aeronautics and Space Administration (NASA), and all but two have been flybys that take detailed observations without the probe landing or entering orbit. These probes make Jupiter the most visited of the Solar System's outer planets as all missions to the outer Solar System have used Jupiter flybys to reduce fuel requirements
Jupiter 2000, the "Cassini" probe flew by Jupiter on its way to Saturn, and provided some of the highest-resolution images ever made of the planet. The "New Horizons" probe flew by Jupiter for a gravity assist en route to Pluto. Its closest approach was on February 28, 2007. The probe's cameras measured plasma output from volcanoes on Io and studied all four Galilean moons in detail, as well as making long-distance observations of the outer moons Himalia and Elara. Imaging of the Jovian system began September 4, 2006. The first spacecraft to orbit Jupiter was the "Galileo" probe, which entered orbit