NASA to test nuclear electric propulsion with 2028 mission to Mars
NASA announced on March 24 that the agency will launch Space Reactor 1 (SR‑1) Freedom at the end of 2028, a nuclear‑electric‑propulsion spacecraft destined for Mars. The mission, unveiled during the “Ignition” event in Washington, repurposes hardware originally built for the lunar Gateway and marks the first operational space nuclear reactor after decades of ground‑only studies. Administrator Jared Isaacman highlighted the shift from concept to flight, while program executive Steve Sinacore described SR‑1 as a “pathfinder” for future nuclear power in space.
SR‑1 Freedom will carry a NASA‑developed nuclear reactor that generates 20 kilowatts of electrical power using high‑assay low‑enriched uranium (HALEU). The reactor sits at one end of a structural truss, shielding the spacecraft’s electronics, while the Power and Propulsion Element (PPE) built by Lanteris Space Systems occupies the opposite end to provide electric thrust. Radiators mounted between the reactor and PPE dissipate waste heat, and solar arrays supply supplemental power during the launch phase before reactor startup. NASA will act as prime contractor, leveraging Department of Energy expertise for reactor design and assembly, and will release the design to industry without proprietary restrictions. The architecture is intended to scale to larger systems such as Lunar Reactor 1, slated for a 2030 launch with power outputs in the hundreds of kilowatts to megawatts range. Upon arrival at Mars roughly one year after launch, SR‑1 will deploy the SkyFall payload, which includes three Ingenuity‑derived helicopters equipped with cameras to survey a prospective human landing site and search for subsurface ice. Mission planners are still evaluating whether the spacecraft will remain in Mars orbit or conduct a flyby to further test the propulsion system.
The launch represents a strategic pivot for NASA, redirecting funds and capabilities from the abandoned Gateway program to a lunar base and a near‑term Mars demonstration. By addressing the four failure modes identified by the Idaho National Laboratory—lack of sustained mission demand, over‑ambitious scope, unrealistic timelines, and fragmented leadership—SR‑1 aims to establish a reliable development pathway for space nuclear power. The effort follows more than $20 billion in prior nuclear‑propulsion studies that never left the drawing board, and its success could enable higher‑energy missions, reduce reliance on solar power for deep‑space exploration, and provide a scalable power source for future lunar and Martian habitats.