Nuclear reactors may go to moon, Mars
NASA is looking at placing small power systems to support outposts in space.
California may be about to shut down its last remaining nuclear power plant, but NASA is looking at placing small, electricity-producing reactors in a couple of farflung locations: the moon and Mars.
A new nuclear power system recently completed a series of tests that has scientists confident that the project — launched in 2015 and called Kilopower — can provide enough safe and efficient energy to establish early settlements in space.
“This is an opportunity for us to go further in space,” said Lee Mason, principal technologist for power and energy storage at NASA, “to eventually bring humans to space, to live there on a permanent basis, potentially, on the moon and Mars ... and allow them to do things that couldn’t be done otherwise with other power sources.”
Developed with the Department of Energy, each Kilopower reactor is small enough to be carried on a rocket and would have enough power to continuously provide as much as 10 kilowatts of electrical power for at least 10 years.
It’s estimated that an outpost on the moon would require about 40 kilowatts, or four Kilopower reactors. That’s enough to power three to eight typical households.
“You could power habitats where crew members could live,” Mason said. “We could power science experiments.”
A suite of safety reviews still must be completed, but scientists working on the project anticipate putting a reactor on the moon by
about 2025.
Mason said the reactor’s design is ideal for the moon, where nighttime can last slightly more than two weeks — which makes relying on solar power there difficult. “You’d have to bring a lot of batteries to make up that power during the [lunar] night,” Mason said. “Alternatively, you use nuclear fission and you could supply continuous power day or night.”
The fission reactor could also be effective on Mars, where dust storms can last months and the strength of sunlight is only about 40% compared with on Earth.
“When we go to the moon, and eventually on to Mars, we are likely going to need large power sources and not rely on the sun,” James Reuter, NASA’s acting associate administrator for space technology, told reporters last month.
How does it work?
Reactors have been sent into space before. The Soviet Union launched dozens of them. The U.S. has sent just one, in 1965.
NASA missions have relied on electricity produced by radioisotope thermoelectric generators that have powered the Voyager 1, the Cassini mission to Saturn and the New Horizons mission to Pluto. But those generators have limited output.
Other NASA nuclear projects have been scrapped because of expense, but researchers developed a potential breakthrough in recent years by using a Stirling engine that converts reactor heat into electricity.
The project proved promising. A prototype with a solid, cast uranium-235 reactor core was developed, and an experiment called Krusty — short for Kilopower reactor using Stirling technology — was conducted in the Nevada desert that started last November and wrapped up in March.
The scientists said the results showed the system not only works but also can withstand multiple induced failures.
“We threw everything we could at this reactor, in terms of nominal and offnormal operating scenarios, and Krusty passed with flying colors,” David Poston, the chief reactor designer at the Los Alamos National Laboratory, said in a statement.
The Kilopower project uses nuclear fission — the process in which an atom is split, releasing a tremendous amount of heat energy. Fission is used in nuclear power plants, although the space reactor is not large.
Mason, who was in San Diego in April talking about Kilopower at a meeting at General Atomics, said the system weighs between 880 and 3,300 pounds. Its core is about the size of a paper towel roll.
The reactor would act like a thermostat — adjusting itself to make sure the core is not running too hot or too cold — which means astronauts would not have to constantly monitor the system.
“Astronauts aren’t going to want to sit at a reactor control system the whole time,” Poston said.
Is it safe?
Even as NASA talks about putting reactors in space, the nuclear industry is going through a difficult time in some places on Earth. The last remaining nuclear power plant in California, Diablo Canyon, is scheduled to shut down by 2025.
But the Kilopower scientists say deploying the reactor will be safe and stable. Poston said NASA follows relevant protocols, including those set by the United Nations. The reactor would not be turned on until it is far from Earth, in order to protect the astronauts and the equipment they’re carrying.
“We’ve done calculations to show that, under all worst-case conditions, we don’t believe that there’s any chance the reactor would come on accidentally, [even] during a launch accident,” Poston told reporters.
Once on the surface, the Kilopower team members said, the reactor will not contaminate the area around it.
One of the chief concerns about nuclear energy is the waste left behind. For example, there are more than 3 million pounds of spent fuel at the San Onofre Nuclear Generating Station.
“We would only burn about 1% of the fuel” during the lifetime of a Kilopower reactor, Mason said. “When it’s done, we would turn it off and it would gradually decay in its temperature and its radioactivity and within months be accessible to humans to move if they chose or leave it where it is. It’s a very safe and benign option for these kind of applications.”
But some aren’t exactly over the moon about the prospect of nuclear power in space.
“I think it’s too dangerous,” said Bruce Gagnon, the coordinator of the Global Network Against Weapons and Nuclear Power in Space, based in Brunswick, Maine.
Among other incidents, the group points to a Russian nuclear-powered satellite that crashed into the Indian Ocean in 1983 and chunks of another that fell into a remote area of the Northwest Territories of Canada in 1978.
Gagnon also worries about launch accidents, contamination and whether projects such as Kilopower may “serve as a Trojan horse” that could lead to using nuclear power in weapon systems in space.
“It’s not the kind of thing we can play games with,” Gagnon said. “One thing we know is technology is not invincible. The Titantic, the Challenger, Fukushima — there are a whole host of examples in the modern age. And when you start mixing nuclear power into the equation, it’s a very dangerous thing.”
What about its cost?
One of the most encouraging aspects of the Kilopower project is its relatively low cost.
The total budget for the Krusty test came in at less than $20 million over three years — a bargain price, considering how expensive space projects can run.
In the early 2000s, for example, NASA spent nearly $400 million on the Project Prometheus nuclear program. Another project originally developed in the 1980s was axed after about $1 billion was spent on research.
Putting the Kilopower project into space will certainly cost more than $20 million. Team members said it’s too early to put a price tag on it.
The presence of the reactors on the moon or Mars would not preclude the use of other sources of energy such as solar rays, batteries or fuel cells, Mason said.
“All those things will be part of the architecture,” Mason said. “But nuclear fission is really the linchpin of them all that will allow us to have that constant, reliable source” of power.