James A. Van Allen; Discovered Earth's Radiation Belts
Thursday, August 10, 2006
James A. Van Allen, 91, who helped launch the United States into space with the discovery that radiation belts surround the Earth, died after a heart attack Aug. 9 at the University of Iowa Hospital.
Dr. Van Allen's realization that charged solar particles are trapped by the Earth's magnetic field in concentric rings around the planet was the first major scientific discovery of the space age. It revolutionized scientific understanding of the Earth and the solar system and created an entirely new field of research, called magnetospheric physics.
His breakthrough came with readings from a Geiger counter he sent into space aboard the first U.S. satellite, Explorer 1.
Ecstatic that Explorer 1 made it into orbit, Dr. Van Allen, William H. Pickering of the Jet Propulsion Laboratory and rocket scientist Wernher von Braun held a triumphal news conference at the National Academy of Science on Feb. 1, 1958, hoisting a model of the satellite over their heads in what became an iconic image of the era.
But it was only later that the true discovery was revealed. The Geiger counter began clicking madly as soon as it reached orbit. The data from that and subsequent satellites showed that Earth was surrounded by a vast series of nested shells of trapped particle radiation, later named the Van Allen Radiation Belts. Those belts helped scientists understand everything from the Northern Lights to the chemical composition of space and alerted scientists to the vast store of knowledge just outside human reach.
"There was a consideration for some time that there had to be some trapped radiation in the Earth's atmosphere," said David DeVorkin, curator of the history of astronomy and space sciences at the National Aeronautics and Space Museum. "But it was a true surprise that there were two different belts and the level of energy. . . . They thought something might have gone wrong with Explorer 1. The darn thing was saturated."
Dr. Van Allen, who had taken only one undergraduate astronomy class, continued to measure and explore the belts around the Earth, then radiation belts around Jupiter and Saturn as well. Until recently, he pursued the discovery of the edge of the heliopause, the outer boundary of the solar wind. He pored over data still coming in from the almost obsolete Volkswagen-sized Pioneer 10.
The affable, down-to-earth scientist, whose University of Iowa office door was marked with his name and longitude and latitude coordinates, took his achievements in stride. His favorite activity, he said, was teaching the beginning astronomy class at Iowa. "It was like going hunting for rabbits and encountering an elephant instead," he once said of the discovery of the radiation belts.
Time magazine put him on its cover in 1959 and again in 1961. President Ronald Reagan gave him the National Medal of Science in 1987. He received the Vannevar Bush Award from the National Science Board in 1991 and the National Air and Space Museum's trophy in 2006, among many other awards.
None of that acclaim stopped Dr. Van Allen, a longtime proponent of unmanned space probes, from speaking out against manned space exploration.
Reagan's endorsement of a $20 billion manned space station was, he said in Congressional testimony in 1985, "so speculative and so poorly founded that no one of lesser stature would have dared mention it to an informed audience."
"I'm one of the most durable advocates for space exploration around," he said just 13 months ago. He supported the Apollo moon landings and missions to service the Hubble Space Telescope, but he said the United States could explore Mars robotically "at far less cost and far greater quantity and quality of results." That prompted a former senator from Florida to respond, "No Buck Rogers, no bucks."