 Its twin Pioneer 11 visited Jupiter a year later, traveling along a highly inclined trajectory and approaching the planet as close as 1.6 "R"J.Pioneer 10 provided the best coverage available of the inner magnetic field as it passed through the inner radiation belts within 20 "R"J, receiving an integrated dose of 200,000 rads from electrons and 56,000 rads from protons (for a human, a whole body dose of 500 rads would be fatal).The level of radiation at Jupiter was ten times more powerful than "Pioneer"'s designers had predicted, leading to fears that the probe would not survive; however, with a few minor glitches, it managed to pass through the radiation belts, saved in large part by the fact that Jupiter's magnetosphere had "wobbled" slightly upward at that point, moving away from the spacecraft.