As scientists mull President George W. Bush's bold new space proposal, nuclear power stands out as one of NASA's best understood and most controversial options for powering the next
generation of spacecraft.
Included in Bush's space initiative, still vague in the details, is a call for "new power generation (and) propulsion" systems for a ship the President has called the Crew Exploration
Vehicle.
In his speech last week, Bush called for the development and testing of the new ship by 2008, with a manned mission to follow by 2014.
"You look at what's possible in that time frame . . . nuclear power makes sense," said Kathy McCarthy, director of nuclear science and engineering at Idaho National Engineering and
Environmental Laboratory. The laboratory conducts research for the Department of Energy, which last year renewed efforts with NASA to study nuclear power in space.
Critics fear that any use of radioactive materials for space flight could lead to accidents.
"We're playing Russian roulette with some deadly stuff here," said Bruce Gagnon, co-ordinator of the Global Network Against Weapons and Nuclear Power in Space, based in Maine. The group
has protested previous launches of NASA rockets carrying radioactive materials, including the launch of Mars rovers Spirit and Opportunity.
Several spacecraft containing radioactive material have crashed. In 1978, a Soviet surveillance satellite called Cosmos 954 crashed into an area in Northwest Canada. No environmental or
health effects were detected. The Soviet Union paid the Canadian government $3 million for the cleanup.
In 1996, the Mars 96 probe, carrying roughly half a pound of Plutonium, malfunctioned and failed to escape Earth orbit, crashing in South America.
To opponents, such accidents are proof enough that NASA should be investing in new kinds of propulsion or power systems instead of trying to create new nuclear-powered systems. "The more of
them you develop, the more of them you launch, the more of a chance of accidents," said Gagnon.
Over the decades, NASA has investigated many advanced propulsion systems for travel beyond earth orbit, most of which have never been proven to work. These range from systems that would use
sails to harness the so-called solar wind, to schemes that utilize a mysterious substance called antimatter, of which NASA says two-billionths of a gram are produced worldwide each year.
By contrast, atomic energy is well understood at least here on earth, where the Washington D.C.-based Nuclear Energy Institute says nuclear power plants supply one-fifth of American power
needs.
John Martinell, a program manager in the strategic planning office at INEEL, said nuclear power would be available "in more near term than some of the other options."
Others feel conventional chemical propellants will play a role in Bush's new plans. "We're going to be pretty dependent on solid or liquid rocket fuel" for any missions to the Moon or Mars
along the President's time scale, said John Douglass, president and CEO of the Aerospace Industries Association.
John Pike, former director of the space policy project at the Federation of American Scientists, said that a form of atomic power called nuclear thermal energy is roughly twice as efficient
as the burning of conventional rocket fuel.
"What it means is that you need half as much mass in orbit, half as much propellant," said Pike.
Through the end of the 1990s, more than $10 billion had been spent on developing nuclear propulsion for space, according to the Federation of American Scientists, though NASA official Al
Newhouse says the figure was considerably less. President George H. Bush supported such research, but the Clinton administration halted that work.
Last year, NASA unveiled Project Prometheus, a renewed effort to develop nuclear power for space. As a centerpiece of the project, which was initially budgeted for $3 billion over five
years, the agency is planning a mission called the Jupiter Icy Moons Orbiter. Slated to launch in 2011 or later, JIMO would send a craft powered by a nuclear reactor to moons Callisto,
Ganymede and Europa, each thought to contain water. Last year NASA awarded study contracts for the mission to Boeing, Northrup Grumman Space Technology, and Lockheed Martin.
According to Joseph Mills, Boeing vice president and project manager on JIMO, the greater source of energy would allow the craft to tour the moons over a period of years, conducting in-depth
science experiments. Previous probes have made relatively modest observations as they have flown by Jupiter's system, unable to tour the moons freely on their own power.
Nuclear power plants work by heating steam to turn turbines, generating electricity. JIMO would use nuclear electric power, a newer technology in which heat converters more directly turn
heat from the reactor into electricity, which in turn would power thrusters. Much smaller versions of the thrusters are used on run-of-the-mill communication satellites.
Previous NASA probes have used small samples of radioactive isotopes to generate heat and electricity. These include Voyager, which is currently leaving the solar system. Cassini, heading
towards Saturn, contains 72 pounds of plutonium.
When Cassini was launched in 1997, activists protested, fearing that the deadly material could be spread into the atmosphere if there were mishaps. NASA said that the material was securely
contained.
Newhouse, director of Project Prometheus, said that safety measures would prevent a possible spread of radioactive material. JIMO will be launched with the reactor off, he said, driven into
orbit by some other kind of propulsion. The craft then will travel in a distant "nuclear-safe" orbit around the Earth, meaning that the craft would take centuries to fall into the atmosphere
if there were an accident. Even then, said Newhouse, nuclear fuel would be shielded to prevent escape.
One U.S. spacecraft, the SNAP-10 experimental nuclear reactor, was launched in 1965, and sits indefinitely in a deep orbit far from the Earth.
But critics are unconvinced.
University City activist Kay Drey said any nuclear reactor launched into orbit is a concern.
"It could get close to Earth, there could be an accident, it could come down to Earth," said Drey, a board member of the Washington D.C.-based Nuclear Information and Resource Service.
Atomic power in space also has its foes among rocket scientists.
"A nuclear engine of large size sounds very scary to me," said Corin Segal, Executive Director of the Institute for Future Space Transportation in Florida.
Reporter Eli Kintisch covers science and technology for the Post-Dispatch.
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