What Good is a Reactor on the Moon?

NASA’s directive to establish a lunar nuclear power plant could provide a new hope for the agency—if it is used intelligently.

You may have noticed that now is not a particularly good time for public science funding in the United States. The core alphabet-soup federal agencies that support scientific research—NIH, NSF, NOAA, DOE, and so on—all face sharp budget cuts and quasi-legal cancellation of existing, approved projects. Even with some likely Congressional restorations, all of these agencies have already seen significant erosion in their missions.

NASA, America’s space agency and a global icon of visionary thinking, is facing a reckoning just like all the others. The agency has abruptly cut 4,000 jobs, in anticipation of a drastically reduced budget. Even its core identity is under assault, as the current administration is directing NASA away from Earth science and planetary exploration. A recent White House executive order (not a law, but indicative of where presidential priorities and spending proposals are headed) declares that NASA has “as a primary function intelligence, counterintelligence, investigative, or national security work.”

That’s quite a turn from NASA’s founding document, which begins by declaring “that activities in space should be devoted to peaceful purposes for the benefit of all mankind.” I recently spoke with a former NASA associate administrator who described the current budget situation as a “Holocaust for science.” He’s Jewish, in case you were wondering.

Hold on. I’m not here to add more hand-wringing to the epidemic of hand-wringing about the trajectory of basic research in the U.S. For sure, if you are inclined to call your representatives and advocate for science, I’m all for it, but the thing that inspired this column was actually a glimmer of good news, or at least promising news: Sean Duffy, the acting administrator of NASA, recently formalized plans to build a nuclear reactor on the Moon, and to have it ready for launch by 2030.

Power with a Purpose

Putting a nuclear reactor on the Moon could be a great idea, as long as it is an idea with a clear and constructive purpose.

Duffy is proposing a reactor with 100 kilowatts of output; I’ve included a conceptual illustration from Lockheed Martin below. By space-exploration standards, that is a lot of power, similar to the output from the solar arrays aboard the International Space Station, and it could support a similar mix of long-term human habitation and scientific experimentation.

On the Moon, nuclear power has significant advantages over solar power. The lunar night lasts two weeks, so a steady solar power supply on the Moon would require not only a large array of photovoltaic cells (the arrays attached to the space station cover an area of 27,000 square feet, or 2,500 square meters), but also a significant system of battery storage for a steady power supply. A nuclear reactor, on the other hand, could operate around the clock, day and night.

There are a lot of intriguing things that we could do with a steady power supply like that. For instance, a lunar nuclear reactor could power a charging station for rovers that would explore the geology and mineralogy of the Moon. Just a small fraction of that power could support long-term lunar astronomy facilities. A upcoming lunar lander will place a small radio telescope called LuSEE-Night on the Moon. It’s a pathfinder for a potential, much larger radio telescope on the Moon’s far side. Just imagine the experiments that would be possible with a stable lunar power supply.

And of course a lunar nuclear reactor could support a human research station, where scientists could conduct local studies of the lunar environment and could learn about the long-term health effects of living on a world with low gravity—an unexplored area of human health in space, and one that’s extremely relevant to any long-term outpost on the Moon or Mars.

Unfortunately, the new NASA leadership has not revealed plans to do any of these things. (Update: At a September 10 NASA press conference discussing possible biosignatures on Mars, Duffy insisted that his agency remains fully devoted to scientific research, despite the torrent of cuts and cancellations. Announcing potential science missions to accompany the planned lunar reactor would be a welcome way to back up that statement.)

The ostensible purpose of the lunar nuclear reactor — formally called fission surface power, or FSP — is to “power architectures for future human space exploration missions.” But for now, those missions are purely conceptual. There is no mission architecture, no budget, no timetable. There is an argument to be made for planning the infrastructure first, so that the engineers can then plan around that capacity. But given a half century of fantasy-based Moon and Mars issued by various U.S. presidents, it’s hard to trust that this “build it and they will come” approach will really work.

I note that Duffy’s directive also does not mention anything about doing scientific research on the Moon. That’s hardly a surprise, given the NASA directive’s explicit focus on competition with Russia and China for lunar resources. Let’s be honest, science wasn’t a driving motive of the Apollo program, either. Geopolitical competition drove the show, and science managed to come along for the ride. But Apollo was a very concrete, goal oriented program. This time around, it’s not clear that there will be any ride at all.

The Nuclear Precedent

There is another important, albeit more indirect, way that a lunar nuclear reactor could boost both human and robotic exploration of space: It could help break a longstanding political and psychological resistance to nuclear technology in space.

For decades, NASA and other agencies have experimented with nuclear-thermal and nuclear-electric propulsion. The former uses the heat from radioactive decay to drive a rocket; the latter uses a nuclear reactor to generate electricity that then powers an ion thruster.

Both technologies have intriguing potential to allow larger payloads and much faster journeys across the solar system. It’s hard to judge that potential, though, since they’ve received only small and inconsistent amounts of funding. The project to build a nuclear reactor on the Moon could sensibly be combined with a methodical program to explore the possibility of moving beyond chemical rockets and entering a new era of space exploration.

Unfortunately (you can see I’m going), that is not the direction NASA is taking. On the contrary, the current administration plans to eliminate these technology-development programs, taking an axe to a joint NASA-DARPA project called DRACO. The elimination of DRACO is part of a broader strategy of retreat and defeat at NASA, where current plans call for a wholesale cancellation of upcoming planetary missions, along with the destruction of existing, still-productive telescopes and spacecraft, such as the renowned Chandra X-Ray Observatory. (Call your representatives!)

Think Atomically, Act Locally

I’m still scouting around for reasons to be optimistic about NASA’s plans, though. There is one promising piece of specificity in Duffy’s directive to build the nuclear reactor on the Moon: The document identifies a primary function of that reactor is to enable “ISRU.”

ISRU is NASA-speak for “in-situ resource utilization,” which in turn is NASA-speak for “doing useful stuff using the materials around you.” The idea is that 100 kilowatts of steady nuclear power would allow a mix of public and private organizations to develop local manufacturing and mining operations on the Moon. For example, they might use 3D printers to turn lunar soil into building bricks, or they might find ways to extract oxygen and water from Moon dust.

We don’t know yet what types of “ISRU” are possible and practical, but that is kind of the point. With a steady power supply, people could begin to experiment. Local mining and manufacturing might then make all types of lunar activities simpler and cheaper.

A human outpost might produce its own water and air, making it much less dependent on resources delivered from Earth. Astronauts might be able to build their own habitats. The same technology could be used for, say, repairing robotic surveyors or for constructing a scaffolding for a lunar observatory.

There is no guarantee any of these activities will happen, either, but if the reactor really does get built, there will be a strong incentive for startup companies to get in on the action. Pilot mining and manufacturing operations would not require top-down government directives to get started. They wouldn’t even be dependent on the presence of human outpost on the Moon.

The emergence of a local lunar technology infrastructure could benefit commercial activity, exploration, and scientific investigation alike. It’s potential path to a totally new kind of activity on the Moon, one that could transcend the geopolitical jockeying that inspired the nuclear reactor in the first place.

It’s hopeful possibility, and I’ll reach for it.