Pioneer 11 was the second mission to investigate the planet Jupiter. It was the first robotic space probe to explore Saturn and its ring system.

Question 1a: When was Pioneer 11 launched?

Question 1b: What was its mission?

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The 2.9 m (9.5 foot) long spacecraft carried instruments to study the magnetic fields, cosmic rays, radio signals, and the atmosphere of Jupiter.

Question 2a: How long did it take the spacecraft to reach Jupiter?

Question 2b: What are some advantages of sending a robot rather than a human being to Jupiter?

Click the Run Time Forward button to see Pioneer 11's approach to the giant planet.

Question 2c: Describe the appearance of Jupiter as seen by Pioneer 11.

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Pioneer 11 passed closest to Saturn on September 1, 1979. At this time, its nuclear-powered generators produced about as much power as a light bulb!

At its close approach, Pioneer saw the ring system almost edge-on.

Question 3a: What do the black markings just below the rings represent?

Question 3b: What evidence suggests that Saturn's rings are not a solid mass?

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Question 4a: Where do sudden changes in Pioneer's orbit occur?

Question 4b: How can you explain these changes?