SCIENCE / MEDICINE : A-Powered Satellite Called Safe

A plutonium-powered satellite that will be launched from the shuttle Discovery this fall to explore the sun’s poles poses little health risk in the event of an accident, space officials said last week.

Ulysses’ scientific instruments will be powered by a radioisotope thermoelectric generator, which converts heat from decaying plutonium into electricity. Environmentalists had opposed two such generators aboard the Galileo spacecraft launched to Jupiter last October, saying a Challenger-like accident could scatter the deadly plutonium over Florida. But Willis Meeks, Ulysses project manager for NASA, said at a news conference the chances of that happening were “very small.”

If plutonium were released into the atmosphere, Meeks said an additional 300 to 400 cancer deaths would occur over 50 years based on the world’s entire population. But a U.S. Energy Department engineer at the briefing said that estimate was much too high.

President Bush is expected to approve the launch of the $750-million Ulysses, scheduled for Oct. 5. Ulysses will be the first spacecraft to orbit over the sun’s poles, providing new insight into solar winds and magnetic fields.