PASADENA, California (AP) -- New measurements from a NASA spacecraft show that the radiation near Jupiter is far more severe than previously estimated, raising concerns about how well future probes could survive missions that take them close in to the giant planet.
National Aeronautics and Space Administration scientists reported Wednesday that the Cassini spacecraft used its Italian-built antenna to measure natural radio emissions coming from Jupiter's radiation belts when it flew past the planet in December.
The data, not measurable from Earth or any previous spacecraft to visit Jupiter, actually showed lower levels of the highest energy electrons, but forced scientists to increase their estimates of the amounts of electrons with slightly lower energy levels.
While not as deadly, the slightly less energetic electrons still pose a formidable threat to the electronics aboard any spacecraft that ventures within 200,000 miles (321,850 kilometers) of Jupiter.
"We got some surprises," said Scott Bolton, a physicist at NASA's Jet Propulsion Laboratory. "This has implications not only for understanding the physical processes in the radiation belts, but also for designing any spacecraft for future exploration close to Jupiter."
NASA has no firm plans to send a spacecraft close to Jupiter, although scientists have proposed a mission called INSIDE Jupiter that would launch in 2003 and reach the planet in 2011. During its 15-month mission, the probe would travel within 2,500 miles (4,025 kilometers) of the planet.
Scientists have long known about the harsh radiation environment at Jupiter. NASA's Galileo spacecraft has endured more than three times the radiation exposure it was designed to withstand since arriving in orbit around Jupiter in 1995.
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