Fission power back on NASA’s agenda : Nature News & Comment

Fission power back on NASA’s agenda

Space-technology report prioritizes nuclear propulsion.

06 February 2012

A mission to Jupiter’s large icy moons, cancelled in 2006, would have been powered by a nuclear reactor.

NASA/JPL

Michael Houts wants astronauts to ride a nuclear reactor to Mars. He is convinced that small amounts of uranium-235 — which has an energy density one million times greater than that of liquid fuels — could power rockets efficiently, using the heat of fission to accelerate small stores of lightweight hydrogen propellant. But although Houts, the nuclear-research manager at NASA’s Marshall Space Flight Center in Huntsville, Alabama, has an unwavering belief in the potential of space-based nuclear power and propulsion, the funding to develop that technology has been inconsistent. This year, he is leading a nuclear-propulsion project with a budget of US$3 million — minuscule in comparison with the $1.3 billion that NASA will spend on space-technology research and development in the 2012 fiscal year. “The funding at times has gone to zero,” says Houts. “You lose the teams and the momentum.”

Yet a report released on 1 February by the US National Research Council could change Houts’s fortunes. Space Technology Roadmaps and Priorities is the first ever community-based document to set priorities for NASA’s space-technology division. The report’s steering committee spent a year canvassing opinion in both industry and academia to create a ranked list of the 16 most important areas of technology development, out of a potential 320 topics. Nuclear power and propulsion came high on the list. “It would change exploration in a fundamental way forever,” says Raymond Colladay, chairman of the committee and former president of Lockheed Martin Astronautics in Denver, Colorado.

Other technologies were ranked higher. For instance, the committee put an emphasis on developing ‘star shades’ and coronagraphs to block the light of distant stars and allow space telescopes to discern the faint light of planets orbiting them. And the report prioritized the development of ways to protect astronauts from radiation on long missions.

But the committee also said that small fission reactors could revolutionize the exploration of the Solar System by both humans and robots. Reactors could support long-lasting experiments on the surface of planets and power missions to the outer Solar System, where the Sun is too distant to provide much power for even the most efficient solar panels. And once human space exploration gets going, nuclear propulsion systems may be essential for multi-year trips to the asteroids or Mars. With twice the efficiency of chemical rockets, reactors could push astronauts not just farther, but also faster than ever before (see ‘Power drive’) — which could help to reduce explorers’ exposure to space radiation.

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