Pioneer 11

By Marty McDowell/NASA

On April 5, 1973, the United States launched Pioneer 11. Pioneer 11 represented a backup in case something happened to Pioneer 10 as it went through the asteroid belt, or going through the intense radiation field of Jupiter. Like Pioneer 10, it left the Solar System after its planetary encounters. Pioneer 11 followed its sister ship to Jupiter (1974), made the first direct observations of Saturn (1979) and studied energetic particles in the outer heliosphere. A plaque was added to each spacecraft in case aliens encounter the craft.

After safe passage through the Asteroid belt on 19 April 1974, the Pioneer 11 thrusters were fired to add another 63.7 m/sec (210 ft/sec) to the spacecraft's velocity. This adjusted the aiming point at Jupiter to 43,000 km (26,725 miles) above the cloudtops. The close approach also allowed the spacecraft to be accelerated by Jupiter to a velocity 55 times that of the muzzle velocity of a high speed rifle bullet - 173,000 km/hr (108,000 mph) - so that it would be carried across the Solar System some 2.4 billion kilometers (1.5 billion miles) to Saturn.

During its flyby of Jupiter on 2 December 1974, Pioneer 11 obtained dramatic images of the Great Red Spot, made the first observation of the immense polar regions, and determined the mass of Jupiter's moon, Callisto.

NASA Pioneer 11 snapped this shot of Saturn in September, 1979. Image courtesy of NASA.

Looping high above the ecliptic plane and across the Solar System, Pioneer 11 raced toward its appointment with Saturn on 1 September 1979. Pioneer 11 flew to within 13,000 miles of Saturn and took the first close-up pictures of the planet. Instruments located two previously undiscovered small moons and an additional ring, charted Saturn's magnetosphere and magnetic field and found its planet-size moon, Titan, to be too cold for life. Hurtling underneath the ring plane, Pioneer 11 sent back amazing pictures of Saturn's rings. The rings, which normally seem bright when observed from Earth, appeared dark in the Pioneer pictures, and the dark gaps in the rings seen from Earth appeared as bright rings.

Where Are They Now?

The last communication from Pioneer 11 was received in November 1995, shortly before the Earth's motion carried it out of view of the spacecraft antenna. The spacecraft is headed toward the constellation of Aquila (The Eagle), Northwest of the constellation of Sagittarius. Pioneer 11 may pass near one of the stars in the constellation in about 4 million years.

Source: NASA.

Share Your Memories!

What do you remember about Pioneer 11? Have you any compelling stories to share? Share your stories with the world! (We print the best stories right here!)

		Your Memories Shared!

" I can remember the Saturn flyby and how exited I was over it. I was 13 years old when that occured in that late summer of '79. I was with my family, camping out in Eastern Nova Scotia, Canada at a place called Lakevale, NS as we had a beach property there. That is about 12 miles NE of Antigonish, NS. We had pitched a big tent there that was designed to hold about six people in it, but overcrowded in with about 15 people! I was tuned in on this Pioneer mission, being the first to encounter Saturn so I fiddled with this small black and white TV set to get the National News on it, and then came the Pioneer 11 announcement that the plucky spacecraft was making the close flyby of Saturn. Astronomy was still a new interest as I just got interested in the subject early the previous year before that. Then the picture show unfolded as I had my eyes glued to that small pitiful television set. What I learn fastinated me. Then on September 1, 1979, as the flyby was occuring, a bunch of us fellows were digging for clams on the beach as it was a nice warm late summer afternoon. That evening, I learned that the spacecraft had made it past Saturn and was still sending back valuable data as the probe was flying away towards deep space. I remained tuned in on the Pioneer space mission for another week as I started Grade eight. That was a cool time for me. I later picked up a copy of the January, 1980 issue of Popular Science and read the Pioneer Saturn article in ernest! That's my story." --CanSat84

Space References (Videos):
Cosmos. PBS, 2000.
Stephen Hawking's Universe. PBS, 1997.
Hyperspace. BBC, 2002.
Life Beyond Earth PBS, 1999.
The Planets. BBC, 1999.
Understanding The Universe. A&E, 1996.