Space nuclear power is nearing critical mass as the final frontier’s next frontier

DRACO nuclear thermal propulsion rocket
An artist’s conception shows a spacecraft firing up its nuclear thermal propulsion system. (DARPA Illlustration)

The idea of putting nukes in space may sound like a national security nightmare, but the right kind of nukes are likely to be a must-have for long-term space exploration.

At least that’s the way a panel of experts at the intersection of the space industry and the nuclear industry described the state of things this week during the American Nuclear Society’s virtual annual meeting.

“In order to do significant activity in space, you need power. And in order to get that power … it’s complicated,” said Paolo Venneri, CEO of a Seattle-based nuclear power venture called USNC-Tech.

Even if you build a hydrogen fuel production plant on the moon, or a methane production plant on Mars, the power to run those plants has to come from somewhere. And studies suggest that solar power alone won’t be enough.

“The sun, it’s great, but only within a certain region of the solar system,” Venneri said. “And so if you want to have sustained high-power applications, you need a nuclear power system.”

George Sowers, a space industry veteran who’s now an engineering professor at the Colorado School of Mines, has run the numbers on the power requirements for a lunar operation that would mine polar ice to produce fuel as well as drinkable water and breathable air for future astronauts. He figures it would take a 2-megawatt nuclear power plant to convert the H2O into hydrogen and oxygen.

Nuclear power is also being studied for in-space propulsion: Amazon founder Jeff Bezos’ Blue Origin is one of the companies working on a Pentagon project aimed at demonstrating a nuclear thermal propulsion system beyond low Earth orbit in 2025. (Nuclear thermal propulsion systems generate heat to drive rocket propellant, while nuclear electric propulsion systems generate electricity for ion thrusters.)

The project is funded by the Defense Advanced Research Projects Agency, or DARPA, and is known as the Demonstration Rocket for Agile Cislunar Operations, or DRACO. Blue Origin’s commercial partners in DRACO are General Atomics, which will design the nuclear reactor; and Lockheed Martin, which will work with Blue Origin on the spacecraft concept.

During DRACO’s initial 18-month design phase, General Atomics is due to get $22.2 million, while Blue Origin and Lockheed Martin have been awarded $2.5 million and $2.9 million respectively. DARPA will issue separate solicitations for future phases.

DARPA is interested in nuclear thermal propulsion because it promises to be as much as five times more efficient than traditional chemical propulsion, with a thrust-to-weight ratio that’s 10,000 times greater than electric propulsion systems.

Venneri said USNC-Tech is helping out Blue Origin and General Atomics on DRACO. “We’re also working with Blue Origin on a few other things, but that’s a TBD [to be determined] in terms of information,” he added.

USNC-Tech is also partnering on nuclear thermal propulsion research with Aerojet Rocketdyne, which has facilities in Redmond, Wash. Venneri said his company is involved in yet another collaboration with Seattle-based First Mode to develop a new type of chargeable atomic battery for space missions. Just in the past few months, USNC-Tech has received NASA grants totaling $250,000 for studies focusing on atomic batteries and an ultra-high-temperature facility for testing materials that could be used in space for nuclear reactors.

In a sense, space nuclear power has been around for decades: Plutonium-powered radioisotope thermoelectric generators, or RTGs, have provided electrical power for NASA missions ranging from the Apollo moon landings and the Voyager deep-space probes to the Curiosity and Perseverance rovers on Mars.

Putting a full-fledged nuclear reactor on a spacecraft, or on the surface of the moon or Mars, would kick things up a notch. Back in 2004, NASA laid out a plan to put a small-scale reactor on a probe that would have studied Jupiter and its moons — but the mission was canceled the following year, due to technical challenges as well as budget limitations.

NASA and the Department of Energy’s National Nuclear Security Administration successfully completed ground tests of a next-generation nuclear reactor nicknamed KRUSTY in 2018 for NASA’s Kilopower space reactor program.

The program’s goal is to put a 10-kilowatt demonstration reactor on the lunar surface by as soon as 2027. But Dave Poston — who designed the Kilopower reactor at Los Alamos National Laboratory and is the chief technology officer for a Los Alamos spin-off called Space Nuclear Power Corp. — said progress has been slow.

“Nothing has really happened for the past three years,” he said. NASA says it’s still working on a request for proposals for a moon-based nuclear power system.

When it comes to nukes in space, safety is a big issue: Under the current regulatory system, each launch of a plutonium-powered generator has to be given presidential approval. Next-generation atomic batteries that use uranium instead of plutonium may not face limits that strict. Nevertheless, any projects that call for launching nuclear material into space will get close scrutiny.

Even within the nuclear industry, there’s a debate over the use of highly enriched uranium (HEU) vs. low-enrichment uranium (LEU) in space. Safety concerns are among the reasons why NASA’s nuclear plans have gotten bogged down.

“I’m not going to debate HEU vs. LEU here,” said Ron Faibish, senior director of business development for General Atomics’ Nuclear Technologies and Materials Division. “I think every system has its merits. I’m just going to say it’s a design issue, and you can design for safety.”

A space policy directive that was issued during the final days of the Trump administration could help smooth the way for nuclear power to become an accepted part of America’s space effort. But Rick Tumlinson, a longtime advocate of space commercialization who’s the founding partner of a space-centric venture capital firm called SpaceFund, said there’s no room for missteps.

“It’s a very confused area, because it’s new, and so that’s going to have to be worked out very carefully,” Tumlinson said. “The other challenge is that there are a couple of countries very interested in space that don’t have to worry about public sentiment when it comes to launching nukes. And I could see them getting a jump, while we’re all wrestling around who regulates this and who does that.”

Will nuclear power become a factor in America’s rising space rivalry with China? That really does sound like a national security nightmare.

Contributing editor Alan Boyle served as the moderator for the “Per Nuclear Ad Astra” panel discussion during this week’s annual meeting of the American Nuclear Society.

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