 Another major issue is the amount of radiation to which a space probe is subjected , due to the harsh charged @-@ particle environment around Jupiter ( for a detailed explanation see <unk> of Jupiter ) . For example , when Pioneer 11 made its closest approach to the planet , the level of radiation was ten times more powerful than Pioneer 's designers had predicted , leading to fears that the probes would not survive . With a few minor glitches , the probe managed to pass through the radiation belts , but it lost most of the images of the moon Io , as the radiation had caused Pioneer 's imaging photo <unk> to receive false commands . The subsequent and far more technologically advanced Voyager spacecraft had to be redesigned to cope with the radiation levels . Over the eight years the Galileo spacecraft orbited the planet , the probe 's radiation dose far exceeded its design specifications , and its systems failed on several occasions . The spacecraft 's <unk> often exhibited increased errors , and electrical arcs sometimes occurred between its rotating and non @-@ rotating parts , causing it to enter safe mode , which led to total loss of the data from the 16th , 18th and 33rd orbits . The radiation also caused phase shifts in Galileo 's ultra @-@ stable <unk> <unk> . 
