Tech Digest

University physicists discover powerful radio waves that may lead to spacecraft damage

LED BY PHYSICS PROFESSOR Cynthia Cattell, University researchers recently used University-designed instruments to unlock one of the biggest mysteries of the Van Allen Belts, named for their discoverer, James Van Allen. They pinpointed the likely physical process that creates some of the most destructive radiation in the Belts, a necessary step toward NASA’s goal of predicting and circumventing damage to spacecraft and space travelers.

A likely culprit is the most powerful radio waves of their kind ever detected in the Belts. The researchers not only discovered the waves but showed that they are capable of accelerating electrons to near the speed of light—which gives them enough energy to knock out computers, pierce spacesuits, and damage the body tissues of astronauts—and they can do it astonishingly fast. Their discovery of these “celestial tsunamis” appears in the journal Geophysical Research Letters.

Physics professor Cynthia Cattell with a model of the STEREO space probe.

The key to the discovery lay in identical instruments designed by Keith Goetz, a University physicist, which are aboard the twin spacecraft of NASA’s STEREO (Solar TErrestrial RElations Observatory) mission, one orbiting ahead of Earth and the other orbiting behind. The idea is to use the widely separated spacecraft to study the sun in 3-D. STEREO was launched in October 2006.

Goetz’s instrument—called TDS, for time-domain sampler—focuses on waves in the solar wind, a stream of charged particles flowing from the sun. The TDS was the first instrument to detect such large waves, and it was no accident. It was programmed to measure more powerful radio waves over shorter time intervals than instruments on previous missions and to regularly discard data on all but the biggest whistler waves it detected.