English: Pioneer 10 image of Jupiter (image A50, taken on 1973/12/01 at a distance of 2557000 Km). Note how the en:Great Red Spot is more prominent when Pioneer passed by than when the Voyager probes later visited Jupiter. This is an approximate color image since Pioneer only had 2 color filters instead of the 3 needed for true color (to human eyes). The spot in general may have simply looked more prominent in 1974 because it is not in the middle of a dark band swirling around it, unlike during Voyager's time. Due to radiation interference with electronics, the probe had many difficulties acquiring complete images, and a clear view of the moon Io could not be obtained when the probe was in range. However, testing the effects of radiation on probe electronics was one of the mission goals. Future probes, such as the Voyagers, benefited from such data.