11 minute read | April.22.2026
With NASA’s Artemis II—the first crewed lunar flyby in more than 50 years—successfully completed, attention is now turning to what’s next: establishing an enduring presence on the moon. Through a series of low-Earth orbit and lunar surface missions over the next several years, the Artemis program is intended to lay the groundwork for a sustained lunar base and, ultimately, missions to Mars and beyond.
Nuclear power is likely to be central to those ambitions. There has been a notable surge in recent government activity in this space, aimed at jumpstarting a commercial nuclear space industry and accelerating deployment timelines. Last December, the President issued Executive Order 14369, Ensuring American Space Superiority, making it U.S. policy to deploy nuclear reactors in orbit and on the Moon by the end of this decade. And this past week, on April 14, 2026, the Administration followed with the National Initiative for American Space Nuclear Power memorandum (NSTM-3), which provides guidance to federal agencies on how to achieve these goals.
Space exploration at scale requires energy systems that are compact, reliable and capable of operating for years in harsh environments where resupply is difficult or impossible. Nuclear systems can provide dense, continuous power for habitats, communications, life-support systems, scientific equipment, mining operations, and on-site resource utilization. That capability becomes particularly important in places where solar power is constrained or unavailable, for example, during the Moon’s approximately two-week lunar night, in permanently shadowed craters near the lunar poles, during Martian dust storms, or in deep space where sunlight weakens with distance from the sun.
Nuclear propulsion may also change the economics and feasibility of deep-space travel. Compared with conventional chemical rockets, advanced nuclear propulsion systems could move larger payloads farther and faster, potentially reducing transit times for crewed missions to Mars, improving mission flexibility, and lowering exposure to radiation and other risks associated with long-duration travel. Over the longer term, nuclear and potentially fusion systems may be essential to support permanent settlements on the Moon or Mars, asteroid mining, and sustained operations across cislunar and deep-space environments.
Now, as the U.S. pursues renewed space leadership, nuclear power is moving from legacy technology to strategic priority. NASA’s Space Reactor-1 Freedom proposal—a near-term nuclear-powered spacecraft—and the administration’s cross-agency National Initiative for American Space Nuclear Power reflect growing momentum behind using nuclear systems to reach space, move through it, and power operations once there. Below we examine how we got here, what comes next, and the legal and policy hurdles that remain.
Nuclear energy in space isn’t just in science fiction—it’s history. Nuclear systems have been part of the space program since the beginning of the space age, providing power and heat for many of the most complex and critical space missions.
NASA has used nuclear power in space nearly since the agency’s inception. With technical support from the U.S. Department of Energy (DOE), nuclear systems have supported over twenty NASA missions in deep space and on Mars.
Historically, space nuclear has taken the form of Radioisotope Power Systems (RPS), which essentially function as a “nuclear battery,” providing low but constant heat or electricity for space operations. Unlike a reactor, an RPS does not rely on a chain reaction. Instead, power in an RPS comes from heat generated by radioactive decay of a contained isotope, usually plutonium-238.
Two types of RPS have long been used in space missions:
While RPSs still have an important role to play in space—such as on the upcoming Dragonfly, a Multi-Mission RTG-powered rotorcraft set to explore Saturn’s moon Titan in the 2030s—their use is inherently limited by the relatively small amount of power produced through radioactive decay.
The power output by an RTG declines over time, beginning before launch, and can reduce power output for the spacecraft by nearly 30% in 17 years of operation.
For anything needing power on the megawatt scale, like a nuclear-powered lunar base or nuclear-propelled spacecraft for deep space exploration, a different option will be needed.
Modern efforts to put nuclear power in space focus on two key areas: propulsion and surface power. Nuclear-propelled spacecraft, including nuclear electric propulsion (NEP) and nuclear thermal propulsion (NTP), can offer high-density power that can enable faster, further space travel—bringing Mars and beyond within reach. Sited nuclear reactors, called fission surface power (FSP), can provide the stable, dense power necessary to support operations or power a base on the Moon or Mars.
Recent presidential administrations have explored deployment of nuclear reactors in space for these purposes.
During both administrations, the Defense Advanced Research Projects Agency (DARPA) collaborated with DOE and NASA on a project called Demonstration Rocket for Agile Cislunar Operations (DRACO), which would have demonstrated an NTP system in orbit. The DRACO project was cancelled in mid-2025 for economic reasons, citing decreasing launch costs as making it hard to justify the up-front R&D investments necessary to develop an NTP system. Nevertheless, the project offered a chance for private industry and the Department of War (DOW) to collaborate on space nuclear power, ties that provide a foundation for what’s coming next.
Recent announcements place nuclear power at the center of U.S. space exploration goals, signaling a new era for space travel and new opportunities for nuclear energy.
Executive Order 14369, Ensuring American Space Superiority (Dec. 2025) sets U.S. policy to deploy nuclear reactors in orbit and on the Moon by the end of this decade. On April 14, 2026, the Administration followed with the National Initiative for American Space Nuclear Power memorandum (NSTM-3), directing federal agencies on how to implement these objectives.
At its core, NSTM-3 is an attempt to leverage government programs to catalyze and de-risk private sector space nuclear deployment. It does this by leveraging parallel, multi-agency efforts to develop and deploy low- to mid-power space reactors—at power levels comparable to existing radioisotope systems—with eventual demonstration and deployment of higher-power space reactors.
By setting engineering goals, sharing early risk, and creating demand signals, these parallel agency efforts are poised to help develop a commercial space nuclear industry.
Private industry is positioned to support this demand. Companies developing space nuclear technologies include BWX Technologies, which is developing reactor and fuel technologies for space applications; Antares Industries, which is advancing nuclear-powered spacecraft concepts for cislunar and deep-space missions; Zeno Power, which is commercializing RPS for satellites and remote applications; and Lockheed Martin, Westinghouse, and X-energy, each of which has participated in government-backed space reactor or power initiatives, illustrate the growing role of private industry in next-generation space nuclear systems.
Mars may be the next major stop—and nuclear power will get us there, too. On March 24, 2026, NASA announced the Ignition initiative. One key element is Space Reactor-1 Freedom (SR-1 Freedom), a proposal to develop the first nuclear-powered interplanetary spacecraft and send it to Mars in the 2028 launch window. SR-1 Freedom will establish flight heritage nuclear hardware, set regulatory and launch precedent, and activate the industrial base for future fission power systems across propulsion, surface, and long‑duration missions. If successful, SR-1 Freedom has the potential to reshape space travel.
Despite clear policy direction to deploy nuclear power in space, substantial regulatory and legal challenges remain. Resolving these issues will be critical if space nuclear systems are to move beyond government demonstrations and into routine commercial deployment.
A threshold question is who regulates these systems before launch, during mission operations, and after reentry or end-of-life disposal. Historically, NASA radioisotope missions have proceeded through an interagency review process involving DOE and other federal agencies. A fission reactor intended for propulsion or surface power would likely face materially greater scrutiny given higher power levels, enriched fuel, launch accident scenarios, orbital safety considerations, cybersecurity, and potential debris or contamination risks.
The U.S. Nuclear Regulatory Commission retains authority over the manufacture, possession, testing, export, and domestic handling of U.S. civilian reactor technology. DOE and DOW may have narrower mission-specific authorities in certain contexts. How those authorities interact for space nuclear systems remains unsettled. Key questions include: who licenses ground testing; who authorizes fuel loading before launch; whether existing terrestrial reactor rules are fit for launch-bound systems; and what agency would oversee in-flight anomalies, recovery operations, or decommissioning of returned hardware.
Commercial deployment would also raise issues beyond reactor regulation itself. Launch providers, insurers, host states, and private investors will likely seek clear rules on indemnification, accident liability, cleanup responsibility, supply chain security, and ownership of nuclear material. Cross-border missions or allied partnerships may also implicate export controls, technology transfer restrictions, foreign investment review, and non-proliferation commitments.
International law presents an additional layer of complexity. The Outer Space Treaty prohibits national sovereignty claims in outer space and makes states internationally responsible for national activities in space, including those conducted by private entities. That framework raises practical questions for nuclear-powered lunar bases, asteroid mining, long-term commercial settlements, and operations involving multiple nations or private operators. Other unresolved issues include how liability conventions, physical protection standards, safeguards obligations, and debris mitigation rules would apply to nuclear reactors or propulsion systems operating beyond Earth.
For industry participants, solving these legal questions may be just as important as solving the engineering challenges. The first viable regulatory framework may become a significant competitive advantage for the nations and companies that establish it.
The next phase of space development may extend beyond fission. While not part of the U.S.’s immediate space exploration plans, fusion energy could play a role in longer-term space exploration.
Fusion-powered spacecraft offer power density, thrust and specific impulse benefits, meaning less fuel to reach higher speeds and sustain acceleration compared to chemical propellants. Fusion could thus enable ambitious goals that the U.S. and other world powers are considering, such as permanent colonies on the Moon and Mars, space access protection, planetary defense, asteroid mining, commercial space travel, and searching for life in the outer solar system. Both fusion and fission could also be deployed in lunar vehicles, for which reliable power is necessary in unfamiliar terrain and the Moon’s 14-day night cycle.
A report by the Fusion Industry Association (FIA), published last year, outlines the roadmap. As terrestrial fusion technologies continue to mature over the coming decade, the FIA recommends developing fusion-propelled spacecraft in relative tandem, beginning with a mid-2030s flight prototype and manned flights thereafter.
The hurdles are both technical, such as perfecting key systems engineering concepts, and regulatory, namely identifying clear standards applicable to space fusion deployment. However, the potential gains—the opportunity to lead advanced space capabilities—are likely worth the effort.
To achieve its ambitious space nuclear goals, the U.S., and its allies, must clear several hurdles.
These challenges are significant, but so is the opportunity. Resolving outstanding legal and policy challenges could help position space nuclear power to become a foundational capability for the next era of exploration, commerce and strategic competition.