Nextweek, NASA will request funding for development of a space nuclear reactor. Forthe first time in a decade, the space agency is seeking funds to proceed withdeveloping the power source, seen as critical to move forward on future space explorationinitiatives.

Accordingto SPACE.com sources, for numbers of months, NASA, the Department ofEnergy, as well as the Defense Department, have discussed ways to restart amulti-faceted space nuclear power program. The Bush White House is seeking torekindle work in this area, an initiative that could have a dramatic rippleeffect in blueprinting future robotic and human missions to Mars, establishinga lunar base, explore Jupiter's ice-covered satellite, Europa, as well as openup for exploration other outer planet destinations.

Accordingto Steven Aftergood, an analyst at the Federation of American Scientists inWashington, D.C., "there is no question that space nuclear power coulddramatically enhance the possibilities for space exploration." Among otherthings, he told SPACE.com, a space reactor would make it possible toundertake a multi-decade mission beyond our solar system.

"Ithink that would be 'uplifting' in more ways than one and I hope to see ithappen in my lifetime," Aftergood said.

Boom-and-bustpattern

Spacenuclear reactor technology has followed a boom-and-bust pattern of developmentsince the 1950s, Aftergood said.

TheU.S. launched one space reactor in 1965, a 500-Watt system that operated for 43days and which remains in orbit. The last U.S. space reactor developmentprogram, a joint NASA-Defense Department effort known as the SP-100, wasterminated ten years ago following the expenditure of nearly half a billiondollars.

Between1967 and 1988, the former Soviet Union hurled spaceward some 30 reactors.

TheU.S. has launched some two-dozen spacecraft utilizing plutonium-poweredelectrical generators -- which are not reactors -- that produce a low level ofelectricity. For instance, the devices energize such spacecraft as the Galileoprobe now exploring Jupiter, the Ulysses probe's exploration of the Sun, andthe Cassini mission, now trekking outward to Saturn. Given a funding go-ahead,the Pluto-Kuiper Belt mission will rely on a nuclear power source.

Outerplanet exploration using advanced radioisotope electric propulsion has recentlybeen evaluated by teams at the NASA Glenn Research Center in Cleveland, Ohio,as well as The Johns Hopkins University Applied Physics Laboratory in Laurel,Maryland.

Ina recent co-authored technical paper, lead author, Steve Oleson of NASA Glenn,said a radioisotope power source for small electrically powered orbiterspacecraft makes possible missions to Uranus, Neptune, and Pluto. While areactor-powered system would provide quicker trip times and more sciencepayload mass and power, radioisotope electric propulsion (REP) alleviates theneed for a reactor and large launch vehicles.

Theuse of space nuclear reactors, Aftergood said, is dictated whenever moderate levelsof electrical power -- tens ofkilowatts or more -- are required in space over an extended period of time.

Burden ofproof

TheNASA nuclear effort is a two-sided coin, Aftergood said. "By the sametoken, space reactors could also be used to power space weapons and othermilitary systems in orbit, attracting the opposition of some arms controladvocates and environmentalists."

"Certainlythere will be public acceptance issues. The burden of proof will be on thegovernment to show that safety risks have been minimized to an acceptabledegree. Even so, some people will be categorically

opposed.But considering the other news of the day, an old fashioned controversy aboutspace nuclear power would come as a relief right about now," Aftergood said.Funding the program will be a more immediate challenge, particularly as thecountry enters a new period of deficit spending, he said.