It follows other space-centered proposals from the Trump administration—and might not be the last.
The White House released a directive Wednesday posing high-level policy goals and explicit directions for multiple federal agencies to drive the development of space-based nuclear systems and technologies.
Space Policy Directive 6, titled the “National Strategy for Space Nuclear Power and Propulsion” and deemed SPD-6 for short, sets a strategic roadmap for several ambitious aims—including to demonstrate a fission power system on the surface of the moon by the mid- to late- 2020s. Those systems operate by splitting uranium atoms inside nuclear reactors, to generate heat that’s converted to electricity.
In journeys into space environments too harsh for more common power sources—or so deep that it’s too dark for solar power or too far to bring much fuel—space nuclear systems can offer a useful means to power spacecraft. They include radioisotope power systems and nuclear reactors for power generation and propulsion.
Though NASA for decades has leaned on certain nuclear generators to power explorations distantly into the solar system, so far, space nuclear propulsion systems haven’t been launched to transcend Earth. But on a call with reporters Wednesday, senior administration officials said space nuclear power and propulsion, or SNPP systems “are fundamentally enabling technologies” for creating a sustainable presence on the moon as intended through NASA’s Artemis missions, and eventually, enabling deeper space missions to Mars and beyond.
“Nuclear power in a variety of ways is going to be important for the moon. As we look towards having a more robust science and more permanent human presence there on the lunar surface, then the fission reactor sizes that we are talking about are needed,” an official said. “So, I think we start with putting a power reactor on the moon. That will in turn support a surface architecture.”
The memorandum sets forth goals to advance SNPP development in support of existing and future missions. They involve: developing processing capabilities to produce fuel fit for diverse planetary surface and in-space SNPP applications; proving a fission power system on the moon’s surface; laying technical foundations to pave the way for in-space nuclear propulsion; and developing next-level radioisotope power systems to extend power reach and robotic exploration around the solar system. SD-6 also establishes that the U.S. “will adhere to principles of safety, security, and sustainability in its development and use of SNPP systems,” which are each expanded on in the document.
Further, the directive defines the roles and responsibilities for leaders of specific federal agencies—spanning NASA, the Defense, Energy, State, Transportation, and Commerce departments, as well as the Nuclear Regulatory Commission—to facilitate the work.
“Harnessing the power of space nuclear systems allows the United States to go farther, explore new frontiers, and aid American security,” White House Office of Science and Technology Policy Director Kelvin Droegemeier said in a statement.
When asked about the nuclear technology-focused directive’s potential to lead to implications related to weapons in space, senior administration officials on the call noted the U.S. follows hard guidelines to maintain peaceful operations in outer space, and added that they’ve also been part of “the international consensus about what safe operation means for nuclear reactors,” and are “very conscious” of nonproliferation issues.
“You'll see in the policy we talked about highly enriched uranium as not being something we want to use unless we absolutely have to,” an official said. “We set a pretty high bar on how to use enriched uranium. And on the wonky end of things, not only are there promising activities with low-enriched uranium, but high-assay low-enriched uranium ... is something where there's a lot of development in, that doesn't have the kind of weapons diversion potential that highly enriched uranium has.”
SD-6 follows five other space policy directives previously signed by President Donald Trump, since he released an executive order to revive the National Space Council in 2017. The fourth directive officially established the U.S. Space Force. SD-6 also comes one week after the White House issued a new, broader National Space Policy.
Though the Trump administration is embarking on the final weeks of its term, officials on the call said this might not mark its last space-related move.
“We're intending to keep working hard, and pressing, and trying to be as productive as possible,” an official said. “So, I wouldn't rule anything out—but nothing is real until the president signs it.”
What America’s space landscape will look like under the Biden administration remains unclear, though the president-elect’s party recently expressed support for “NASA’s work to return Americans to the moon and go beyond to Mars, taking the next step in exploring our solar system.”
“One of the things you try to do with space policy is to line it with enduring long-term national interests—economic, security, scientific interests. And so, I can't speak to what the Biden administration would do or not do, that’s not really my area of expertise,” the senior administration official said. “But I would say that we see this policy as representing a broad consensus within the community, and being in alignment with long-term national interests. So therefore I am hopeful that it will continue—but that's not my decision to make.”
Officials on the call did not confirm whether they’ve met with the Biden transition team.