"The fact that the country is willing again to consider use of nuclear energy for commercial power may improve the prospects of applying this technology to space exploration." - George Schmidt, Marshall Space Flight Center

With increasingly ambitious missions planned to Mars and beyond, and with solar energy having demonstrated its limitations, engineers and managers inside and outside NASA say nuclear energy may be powering its way to a new dawn in space.

It's a possibility made more likely by recent shifts in U.S. energy and military policies. It's also a move anticipated by antinuclear activists, who are already planning their opposition to any effort to use nuclear power in space.

Fueled by the desire to go farther and faster with fewer dollars, managers at NASA's Jet Propulsion Laboratory -- where many of the agency's robotic missions are conceived and carried out -- are analyzing how to justify the use of nuclear power in space, both technically and in terms of the benefit to science.

"We've been thinking about this, and trying to raise it as a question that warrants some consideration, for a couple of years," says Firouz Naderi, a longtime JPL manager and newly appointed leader of the Solar System's Exploration Programs Directorate. "I think we are going to raise it again and see if the [political] system is amenable to it."

In an interview at his JPL office, Naderi said any such political balloon would have to be floated in Washington by NASA headquarters.

"I believe that if a good case can be made, not only for the science return but for safety, then I could see that [nuclear power] could be in our future," he said.

Others think Naderi may be right. And support could come from the top.

President Bush's recently released energy plan features increased reliance on nuclear power back here on Earth. In several interviews, scientists and mission planners said they were hopeful this might put space-based nuclear power generation back on the table after suffering from years of what they call misinformation.

"The fact that the country is willing again to consider use of nuclear energy for commercial power may improve the prospects of applying this technology to space exploration," said George Schmidt, deputy manager of the Propulsion Research Center at NASA's Marshall Space Flight Center.

Two sides, very far apart

The last nuclear-powered spacecraft launched by NASA was Cassini in 1997. Antinuclear activists protested heavily against it, saying a launch accident or potential mishap in a 1999 Earth flyby en route to Saturn could kill billions of people who might develop cancer after contact with radioactive material.

Cassini scientists have called such claims "hogwash," saying that the radiation risk is less than normal background radiation in the air or in rocks.

Before the launch, NASA did admit that "there is a small potential for public health effects." But in 1997, Cassini project manager Richard J. Spehalski said the public was "badly misinformed by alarmists."

Spehalski said that even in the highly unlikely event that the 73 pounds of plutonium on board were somehow released into the atmosphere in a breathable form, and ingested, "the radiation dose an individual would receive over a 50-year period from that exposure would be ... 15,000 times less than a natural lifetime exposure."

In the end, there were no Cassini accidents. Yet the dangers still are debated.

Few debate the potential benefits of nuclear power in space. The life of a Mars rover could be extended from days to years. Maneuverability would be measured in miles instead of feet. And many engineers agree that a human trip to Mars would go from highly impossible to practical.

Further, if humanity is ever to leave this planet permanently and set up colonies on the Moon or Mars, a nuclear power station would be nearly indispensable, most space industry experts agree.

No nukes in space

As talk of space-based nuclear power increases, so do the efforts of opposition groups.

Bruce K. Gagnon is a coordinator for the Global Network Against Weapons and Nuclear Power in Space. The organization represents 150 groups around the world with, Gagnon says, millions of members.

Gagnon said the groups have been expecting space-based nuclear power initiatives to resurface, and they've been making plans to mount a concerted effort against all uses, from planetary exploration to military. The U.S. military would benefit from having nuclear generators in space to power huge orbiting radar stations for reconnaissance. And Bush is also pushing for a fresh look at the so-called Star Wars missile defense system.

"We see a deadly connection between each of them," Gagnon said, arguing that the nuclear industry views space as a new market and would love to get a foot in the door any way it can.

Gagnon said the missile defense system would use nuclear energy aboard satellites to refuel lasers that would shoot down foreign missiles. Bush has not committed to any specific system, however, and some expect the weapons would ultimately be ground-based or mounted on ships or aircraft.

Gagnon also argues that relying on nuclear power tends to kill research into alternatives, such as solar power. "When you go with nuclear power you're basically saying nothing else works," he says.

Exploration, not war

Meanwhile, those who plan missions to Mars and beyond have a more modest goal: getting there. And they say that a new generation of nuclear propulsion systems is safe.

Radioisotope thermoelectric generators, or RTGs as they are called, use the natural decay process of plutonium to generate heat needed to protect a spacecraft in the cold environment of space. Some of the heat is converted to electricity, which can be used for flight propulsion or to power a surface rover.

In future plans, conventional chemical rockets would be used to launch spacecraft powered by RTGs, and the reactors would not be turned on until after they are launched. Still, critics fear a release of plutonium during launch or in the atmosphere, when a rocket is accidentally or intentionally blown up.

In the case of such an accident "the radioactivity in the reactor is nil, less than that received by laying on the beach in sunny California or in Long Island," says Mohamed S. El-Genk, director of the Institute for Space and Nuclear Power Studies at the University of New Mexico.

Gagnon, however, says the greatest danger might come well before a spacecraft is even launched. In order to use nuclear power in space, he points out, the Department of Energy would have to ramp up plutonium production.

"As you contemplate expansion of the use of nuclear power in space, you'll have a dramatic escalation in worker contamination," Gagnon said.

And finally, Gagnon said a launch accident is inevitable, due to faulty parts, human error, or sheer odds.

Plenty of company

If nuclear power returns to space, it will find a lot of company. In the most recent tally provided by the Bulletin of Atomic Scientists, there are roughly 75 nuclear devices in space, 38 from the United States and 37 from Russia. Of these, 46 are in Earth orbit, 12 were left on the Moon or Mars, and 17 power deep-space probes.

In 1964, for example, an American satellite failed and re-entered Earth's atmosphere. As planned, it jettisoned its nuclear payload, releasing radiation over the Indian Ocean at an altitude of 75 miles, according to the Bulletin.

In 1973, the Apollo 13 spacecraft carried an RTG to be used to power a seismic station on the Moon. The mission was aborted and the spacecraft returned to Earth. The RTG was attached to the lunar module, which broke up on re-entry. NASA officials say the RTG re-entered intact, with no release of plutonium, and now sits on the floor of the Pacific Ocean.

In 1978, a Soviet radar reconnaissance satellite malfunctioned and crashed in Canada's Northwest Territory, releasing thousands of highly radioactive fragments into a lake and the surrounding area.

No evidence has tied these mishaps to any cancer cases or deaths.

Destination Mars

Still, over the years, political and social pressure from these accidents, and others in terrestrial nuclear reactors, have combined to compel NASA to design Mars probes and rovers that rely on solar power.

But for robotic exploration, especially on the surface of a planet far from the Sun, with nighttime darkness and changing seasons thwarting solar collectors, nuclear power would be an indisputably more powerful exploration tool.

A stark example of solar power's shortcomings was provided by the successful Mars Pathfinder mission in 1997, which worked in tandem with the Sojourner rover to beam back pictures of the surface of Mars. While outlasting its 30-day life expectancy, the craft's batteries died just shy of three months after landing.

Researchers expected the batteries to die, because they required constant recharging from the solar panels. Solar energy cannot be used directly, because it fluctuates so much.

And solar panels are heavy, not to mention complicated to unfurl in space or on a planet.

How to kill a mission

Bob Anderson, a geologist and mission planner, said in a recent interview at JPL that the weight of solar panels and their poor performance compared to nuclear power severely constrain the amount of science that can be done for a given mission's price tag.

"Two things will kill a mission," Anderson says. "Power and mass."

And future Mars missions will require more of both. A pair of missions in 2003 will send the most advanced and capable rovers ever designed to study Martian geology and search for signs of water. If there, this water could provide the trail to any past life that might have existed on the Red Planet.

The craft may be sent inside giant craters, where orbiting spacecraft have spotted signs of water. But to ensure safety, the spacecraft will land in flat areas, likely near the crater center.

"But the best information is probably in the rim," Anderson says.

Anderson is helping engineers design rovers that will allow the geologist to remotely drill into rocks and figure out what they're made of. It is a critical science tool, but also a tremendously power-draining activity, he said.

Nuclear power could turn short, daytime-only missions into long, 24/7 operations, Anderson said. He notes, however, that rovers would have to be redesigned to make all their parts capable of sustaining such a long mission.

Naderi, the JPL manager, worries that Americans have been jaded into assuming that going to Mars is a relatively simple operation nowadays. But given that favorable planet alignments limit Mars missions to launching every 26 months, he laments solar-powered rovers die before the next one can be launched.

"People think [landing on Mars] is like driving to Grandma's on Sunday," Naderi said. "But it is expensive and it is horribly difficult to land on Mars. Once you do, you want to last more than 90 days."

Living on the Moon

While nuclear power can improve the efficiency of a rover, some say it is imperative for more ambitious missions.

An increasingly vocal group of space enthusiasts argues that the post-Apollo space program is stagnant due to the lack of a major goal. Many think that what's needed is a firm plan to set up permanent human colonies on the Moon or Mars.

Peter Eckart, of the Institute for Astronautics at the Munich University of Technology in Germany, says that if a lunar base is to be built anywhere except at the poles, where sunlight is constant, then "the only reasonable engineering solution is to go with nuclear power."

Likewise, others say, any future colonization of Mars will likely depend not just on nuclear electric propulsion, but nuclear power generation on the surface. Most engineers question whether even the most perfectly situated site can be sustained by solar power. And at best, these sites would not necessarily be located where researchers would want to explore.

Despite the benefits of nuclear power, Eckart is not one to discount the dangers.

"I'm personally not too much in favor of using nuclear power on Earth, if we can avoid it," he said after a recent conference on space colonization at Princeton University. "But in space, it's not a problem."

Eckart calls the fear of contaminating the lunar surface with radiation "total nonsense, because up in space there's so much radiation already -- all the galactic and cosmic radiation, all the stuff that's coming in from the Sun. A nuclear reactor does not make a difference at all. The only risk is launching it, and there you have to be careful from an engineering point of view."

Such a system would be launched in safer pieces, then assembled once at its destination, providing a further measure of safety, proponents say.

Several experts say that whether nuclear power flies again depends upon public opinion. And while a significant chunk of the American public has traditionally held a dim view of nuclear energy, there is evidence that opinions can change, at least in the face of a compelling need.

Five years after the Three Mile Island accident in Pennsylvania, a nonpartisan Field Institute poll found that roughly 61 percent of Californians opposed nuclear power. But a new poll, released this May, found that about 59 percent of Californians were in favor of building new nuclear plants.

Pollsters suggested the obvious: Rolling blackouts and soaring electricity bills had altered views.

Most space industry experts say there is no direct relationship between the fate of Bush's energy proposal -- which offers tax breaks to the nuclear energy industry and promises to re-evaluate a controversial limitation on reprocessing nuclear waste into reusable fuel -- and the potential for a nuclear powered space program.

But several of those interviewed by SPACE.com expressed optimism for a political and social trickle-down effect.

"In order to line up national support, we need a NASA mission or missions that would inspire Americans of all ages," says the University of New Mexico's El-Genk.

Dusty plan, dying experts

A potentially more difficult challenge also looms, especially regarding the construction of large-scale nuclear power plants to support Mars or lunar colonies.

Even if the social barriers were suddenly lifted, it is unclear how quickly NASA could ramp up the necessary technology, given that three decades worth of plans for nuclear propulsion and space-based power generation are stuffed away in dusty drawers around the country.

Professors are loath to bring the topic up, says El-Genk, and a generation of engineers who understood the technology is largely retired or dead.

"University education in this area is nil, due to the very low enrollment in nuclear engineering departments during the last two decades and the closure or combining of more than half the nuclear engineering departments that existed in the 80s," El-Genk told SPACE.com.

With this dying generation may die the dream of sending humans to Mars. Or, at the least, the dream might be deferred until a new generation of engineers can be re-educated.

So despite glimmers of hope within the space community, there is a realization that a tremendous public and political education effort would be needed to get nuclear energy off the ground and back into space.

Some worry the obstacle might be insurmountable.

Gary E. Mueller, an associate professor of nuclear engineering at the University of Missouri-Rolla, said he's hopeful that Bush's efforts will translate into increased use of nuclear power in space. But, tossing another obstacle into the equation, he says NASA will have to find new money to support research.

"Some leadership in Washington, which I hope the Bush administration will provide, and leadership at NASA, which will not happen with [Dan] Goldin's administration, is needed to clear up and shift political will and public opinion," Mueller said.

If President Bush were to push for a nuclear-powered space program, the effort would have a familial echo.

Bush's father spoke in 1989, on the 20th anniversary of the first Moon landing, of America's need to return to the Moon and lay plans for putting humans on Mars. His speech set no dates but spawned a flurry of studies and committees, resulting in recommendations that included nuclear power as a cornerstone for any possible Mars missions.

Twelve years later, there are still no plans for a humans-to-Mars mission. And though space-based nuclear power may be on the brink of a return to the political spotlight, it is also an idea with an uncertain future.

Global Network Against Weapons & Nuclear Power in Space 
PO Box 90083 
Gainesville, FL. 32607 
(352) 337-9274 
Web: http://www.space4peace.org
Email: globalnet@mindspring.com