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University of Iowa News Release

Feb. 27, 2003

U.S. Space Pioneer Van Allen Toasts Pioneer 10 Spacecraft

“Like Gen. Douglas MacArthur, we all fade away.”

That is how Dr. James A. Van Allen, U.S. space pioneer and Regent Distinguished Professor in the University of Iowa department of physics and astronomy, reacted to the Feb. 26 NASA announcement that the working life of Pioneer 10, NASA’s most venerable spacecraft, had come to an end.

Launched March 2, 1972 on a 21-month mission, the spacecraft was the first spacecraft to make direct observations and close-up pictures of Jupiter. However, Pioneer 10 and a sister craft –- Pioneer 11, launched April 6, 1973 – were more than the first spacecraft to visit the outer planets. They were very important in the professional life of Van Allen, best known for his 1958 discovery of the Earth’s bands of intense radiation -- later known as the Van Allen radiation belts – using instruments aboard the first successful U.S. satellite, Explorer 1.

“Both Pioneer 10 and Pioneer 11 have been a very central part of my professional research career,” Van Allen said.

In 1969, Van Allen and his colleagues began constructing scientific instruments for the two spacecraft. In July 1972, they held their breath, then celebrated as Pioneer 10 entered and ultimately succeeded in passing through the asteroid belt. When Pioneer 10 flew past Jupiter in December 1973, Van Allen used his energetic particle instruments to make the first-ever survey of Jupiter’s radiation belts.

“That was a very exciting period in our lives,” he recalled. “The Pioneer 11 second-ever encounter with Jupiter a year later confirmed our findings. And the Pioneer 11 first-ever encounter with Saturn in September 1979 was another exciting time when we made the discovery and survey of Saturn’s radiation belts.”

Right through his 1985 retirement from active teaching, Van Allen continued to monitor cosmic ray data from Pioneer 10 and Pioneer 11 as the two craft continued on trajectories that took them out of the solar system and, eventually, will lead them out of the heliosphere, the area of the sun’s influence.

The end for Pioneer 11 came in September 1995 when its last transmission was received. Pioneer 10, suffering from a feeble and decaying radioisotope power source, sent its last signal Jan. 22, 2003 at some 7.6 billion miles from Earth, roughly 82 times the distance between the sun and the Earth. Van Allen said that when the call from NASA came last week, he was ready for it.

“It’s been a tremendous mission. It exceeded our expectations; we’re not emotional about it,” he said. Then, hinting that the Pioneer saga may not have ended entirely, he added, “I’m still writing scientific papers about it.”

STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Suite 301, Iowa City, Iowa 52242-2500.

CONTACT: Gary Galluzzo, 319-384-0009,