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<b>Nuclear-Reactor Spacecraft Poor For Astronomy</b><br /><br />LINK<br /><br />Spacecraft powered by nuclear fission reactors are of limited use to astronomers, the US National Research Council panel has concluded. The report calls into question NASA's multi-billion-dollar Prometheus project, which aims to develop such spacecraft for future missions to the Moon, Mars, and the outer solar system.<br /><br />Early reactor technology was used in space once by the US in 1965 and a couple of dozen times by the Soviet Union from 1967 to 1988. Now, NASA hopes to improve on the technology, which releases heat by splitting uranium.<br /><br />The "nuclear electric propulsion" NASA is focusing on could provide up to a million watts of electricity to power instruments and propel spacecraft using a stream of ions. This could support many more scientific instruments, beam back more data, and allow spacecraft to visit more targets than current technologies.<br /><br />But the NRC report finds that the reactors would be virtually useless for - and could even hamper - observations of astrophysical phenomena beyond our solar system.<br /><br />"Reactors are messy things," says NRC panel member Gary Bernstein, an astronomer at the University of Pennsylvania in Philadelphia, US. "They generate huge numbers of radiation particles and gamma rays." <br /><br />He says these by-products of fission could effectively "blind" space telescopes such as Hubble, Spitzer, and Swift if the reactors operated near the Earth, as they did in the past. "We didn't see a benefit of this technology for any kind of pure science that peers outside the solar system or does fundamental physics tests," he says. <br /><br />Hot hydrogen<br />Nor did the panel find that NASA's nuclear programme would support its planned human missions. The NRC acknowledged that fission reactors would be useful for both space travel and long-term human bases on the