IT IS going to take a lot longer to get a nuclear-powered spaceship to Jupiter鈥檚 icy moons than NASA thought: the space agency鈥檚 first designs for a nuclear spacecraft are too massive to get out of Earth orbit, New 杏吧原创 has learned.
NASA鈥檚 initial design for Project Prometheus 鈥� a $3 billion plan to send a probe powered by a nuclear reactor to Jupiter鈥檚 three icy moons in 2008 鈥� weighs in at a hefty 20,000 kilograms. That is far too heavy to reach Earth escape velocity even with planned upgrades to the US鈥檚 two biggest launch rockets. However, project director Alan Newhouse remains hopeful: 鈥淲e think we can get the mass down,鈥� he says.
Despite Newhouse鈥檚 optimism, the setback will delay the mission further. Earlier this year, NASA said the Jupiter moons mission would fly 鈥渘o earlier than 2011鈥� 鈥� three years after the original proposal 鈥� but it is likely the actual launch will now be even later.
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That鈥檚 because Prometheus is far more ambitious than the 6-metre James Webb Space Telescope. JWST is the follow-up to Hubble and is supposed to fly in 2011, but its design was only selected last year. So the chances of Prometheus getting off the drawing board and into space on the same timescale are extremely slim.
The mission to Jupiter鈥檚 moons is estimated to last 15 years. NASA hopes that using nuclear power will overcome the power restrictions that hindered previous missions to Jupiter and beyond.