Some on the Moon's surface, some in orbit. How does 5 years sound? Do-able, right nerds?
The nukes-in-space ambitions of the current US administration have taken a step forward – and the US Office of Science and Technology Policy has just published its hopes for who does what.
The initiative [PDF] spells out expectations from an inter-agency perspective: NASA and, as the document refers to it, the Department of War Defense [still its legal name and we're sticking to it – Ed] are to conduct "parallel and mutually-reinforcing" design competitions to develop low- to mid-power space reactors "in orbit and on the lunar surface".
The Department of Energy is also involved (it controls the US stockpile of nuclear material). It has been instructed to "provide an assessment on the readiness of the US nuclear reactor industrial base to produce up to four space reactors within five years."
NASA has 30 days to kick off a program for a mid-power space reactor ready for launch by 2030. A lunar variant is required, as is an option for nuclear electric propulsion.
The Department of Defense has 90 days to develop an analysis and use cases for a mid-power in-space reactor by 2031. Its development is "pending availability of funding."
The idea of nuclear reactors in space is nothing new. As recently as 2022, NASA was planning for a nuclear future on the lunar surface. The agency's acting administrator, Sean Duffy, directed the agency to develop a plan in 2025, and the current administrator, Jared Isaacman, went further during the Ignition presentation in March, calling for the use of a fission reactor on interplanetary missions as soon as 2028.
The mid-power reactors will need to provide at least 20 kWe during "at least" three years in orbit and five years on the lunar surface. At least one of the designs must be extensible to 100 kWe, and the initiative calls on NASA to consider a low-power variant that could provide 1 kWe. The low-power option, according to the initiative, "offers lower cost and schedule risk."
Launch remains atop whatever is available in 2029, which means one of Blue Origin, SpaceX, or United Launch Alliance crafts. Not in the current roster of launchers is NASA's Space Launch System (SLS), which transported a crew of four astronauts around the Moon in April 2026. The final SLS launch is likely Artemis V, slated for a lunar landing mission in 2028.
The initiative, which spells out the inter-agency cooperation required and the sharing of funding, is an indication that this time the US administration is serious about nuclear reactors in space, after decades of ideas bouncing around NASA and billions spent with little result.
As with many such grand plans, however, much will depend on funding and focus that could extend beyond the end of the present US administration. ®