Looking Anew at Nuclear Power for Space Travel

[Susan L Gawarecki <loc@ICX.NET>]

Looking Anew at Nuclear Power for Space Travel

February 12, 2002 



By WARREN E. LEARY



WASHINGTON, Feb. 11 - NASA says the future of space

exploration is rooted in the past, and it is time to look

again at nuclear power as the way to the stars. 



Years after largely abandoning efforts to apply atomic

power to space, NASA last week announced a Nuclear Systems

Initiative that it said could jump-start space exploration

within a decade. Tucked away in the Bush administration's

proposed 2003 budget for the agency is $125.5 million to

begin moving NASA into a new nuclear age. 



In the early days of the space program, NASA looked into

nuclear-powered rockets as a possible means of sending

humans to Mars and other planets. The agency tested some

atomic rocket engines, but abandoned the effort because no

missions arose to use them. In the new program, nuclear

reactors would not directly produce thrust to propel

rockets as in the earlier program, but would be activated

when far from Earth, to supply power for other types of

engines. 



The agency also developed electric generators powered by

radioactive materials that have been flown on two dozen

spacecraft, including the Pioneer and Voyager outer planet

probes and piloted Apollo missions to the moon. In 1997,

the launching of another probe with a nuclear generator,

the Cassini mission to Saturn, drew protests from some

environmental and antinuclear groups that worried that a

rocket explosion might spread radioactivity. 



Now only one of these power units, called radioisotope

thermoelectric generators, or R.T.G.'s, remain in the

civilian space inventory, and officials say it is time to

reopen production lines. The new program, they say,

presents an opportunity to design and build new generators

that are more efficient, require less nuclear fuel and can

be used on more varied spacecraft. 



NASA is proposing to spend $950 million over the next five

years to develop new types of atomic-powered generators to

supply electricity for spacecraft, and also to build

nuclear electric rockets to propel ships through space at

greater speed than possible with traditional rockets. 



The NASA administrator, Sean O'Keefe, said nuclear power

would help space explorers "conquer the problems of

distance and time." It takes a long time for spacecraft to

travel within the solar system, he said, noting that it

would take more than a decade for a probe to reach Pluto

using current technology. 



The continued exploration of the solar system and the space

beyond is being held back by the limits of conventional

chemical rockets as well as existing spacecraft power

supplies, which mostly use solar-powered cells, Mr. O'Keefe

said. 



Officials said the nuclear program would be conducted with

the Department of Energy, which has the facilities and

expertise to construct nuclear power units. Earl Wahlquist,

of the Energy Department's Space and Defense Power Systems

Division, said the fuel most widely used in R.T.G.'s,

plutonium-238, is no longer produced in the United States.

Mr. Wahlquist said that his agency would use NASA funds to

buy the necessary plutonium from Russia. 



Dr. Edward Weiler, head of space science at NASA, said

nuclear generators were necessary for outer planet

missions, where sunlight is faint. Jupiter, he noted,

receives only 4 percent of the sunlight that reaches Earth.

The Galileo spacecraft, which has been exploring Jupiter

and its moons, is powered by two R.T.G.'s. 



But new nuclear generators also could revolutionize studies

of near planets, he said. The Smart Lander mission for

Mars, which was scheduled for launching in 2007, will be

delayed for two years to convert it from a solar-powered

rover to one run by a nuclear unit. For roughly the same

cost, he said, the 180-day solar-powered mission could be

stretched to 1,000 days with nuclear power and the machine

could range up to 50 miles instead of a mile or two as it

looks for signs of life. 



For propulsion, a nuclear reactor could be used as a heat

source to power new kinds of engines, like the electric ion

drive successfully used on the recent Deep Space 1 mission.

That spacecraft used solar power to run an engine that

continually pushed it with very low thrust to high speeds.

This approach used fuel 10 times as efficiently as

conventional chemical rockets, which burn for a few minutes

and require the spacecraft to coast for the rest of its

trip. 



A nuclear-powered ion drive could sent a craft to Pluto in

half the time as existing rockets, Dr. Weiler said. 



A major priority of the new program will be safety, he

said, and developing technology that will virtually

eliminate any risk to the public if something goes wrong,

like a launching accident. 



"We will design these new systems for a worst-case

scenario," Dr. Weiler said, "They'll be designed to survive

a rocket blowing up, or one going up and then coming down

and hitting the ground. If you can't guarantee this in your

design, then we don't want to talk to you." 



NASA officials said the systems they envisioned would be

launched by conventional rockets and not activated until

safely in space. Once operating, they said, neither

electric power supplies nor reactors powering engines would

leave residual radiation. 



Still, there is some opposition to the initiative. The

Global Network Against Weapons and Nuclear Power in Space,

a group based in Florida, said it remained opposed to any

nuclear systems in space and speculated that any new

technology developed might be applied to military uses. 



Dr. Weiler said nuclear energy was not only safe but

necessary for further space exploration. The limits of

current power and propulsion systems are now starting to

limit space science, he said. 



"We are trying to continue the exploration of the solar

system in covered wagons," he said, "Now it's time to

switch to the steam engine and build railroads to explore

the solar system like railroads contributed to the

exploration and expansion of this country."



http://www.nytimes.com/2002/02/12/science/12NUKE.html?ex=1014547367&ei=1&en=135220b22bc4e285

-- 

.....................................................

Susan L. Gawarecki, Ph.D., Executive Director

Oak Ridge Reservation Local Oversight Committee

We've moved!  Please note our new address:

102 Robertsville Road, Suite B, Oak Ridge, TN 37830

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