NASA says its SR-1 Freedom spacecraft will be “humanity’s first fission-powered spacecraft to travel outside Earth’s orbit,” with launch planned for late 2028. On Oct. 20, 2026, the agency’s Glenn Research Center in Cleveland announced contract actions meant to speed up the spacecraft’s nuclear power module, the reactor-and-generator assembly at the heart of the design. The ship’s job is to prove nuclear electric propulsion in deep space and then deliver three Mars helicopters, a pairing that NASA has described as a way to build fission power for both Mars and the Moon.
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Two parts of the nuclear power module
The power module sits at the end of the spacecraft’s long boom, away from the rest of the vehicle. Per NASA’s Oct. 20 release, written by public affairs specialist Jacqueline Minerd, it has two main parts: a fission reactor that generates heat, and a power conversion system that turns that heat into electricity for spacecraft systems and the electric thrusters. The reactor is being designed and developed by the Department of Energy’s Idaho National Laboratory, and the conversion hardware will be integrated with it. In plain terms, the reactor makes heat, the Brayton system turns the heat into electricity, and the electricity drives the thrusters that push the craft through space.
Sierra Lobo Inc. will supply the closed Brayton cycle power conversion system, the Glenn release says. That work falls under the Space Flight Systems Development and Operations Contract III, which NASA awarded in 2024 and which supports hardware work at Glenn. NASA’s announcement of that contract names Sierra Lobo of Fremont, Ohio as the awardee, puts its maximum potential value at about $282.1 million, and describes a three-year base period with two two-year options.
NASA’s SR-1 Freedom mission page adds specifics about the hardware. It lists a 20-kilowatt electric closed Brayton cycle power conversion system, an advanced electric propulsion system built around a 12-kilowatt Hall thruster, and a reactor fueled with high-assay low-enriched uranium. The page says the mission will demonstrate nuclear electric propulsion for the first time, with Mars as the destination for a flyby and for deploying science payloads.
Safety rules for a reactor that stays off until it leaves Earth orbit
The first question about any nuclear spacecraft is what happens if the rocket fails, and NASA’s answer is a sequencing rule. The reactor remains inactive until the spacecraft leaves Earth orbit, so the launch itself carries the fuel in an unpowered state. NASA also lists interagency safety reviews, continuous oversight by a NASA chief safety officer, regulatory compliance, and a design process focused on hazards, failure tolerance and nuclear safety.
Those commitments are part of the project plan rather than test results, and the release gives no reactor power-up date or thermal rating. The distinction matters for how the claim should be read: NASA is describing a design intent for a reactor that has not yet flown, and the interagency reviews it names are the checkpoints where that intent would be tested before launch.
SkyFall: three Mars helicopters evolved from Ingenuity
The spacecraft is more than a propulsion demonstration. SR-1 Freedom is billed as the carrier for SkyFall, a science mission built around three Mars helicopters evolved from the Ingenuity helicopter that flew on Mars. NASA’s SkyFall page says the rotorcraft will survey the planet and gather data including subsurface ice mapping, weather analysis and climate history, and will scout landing sites for future missions, including crewed ones. AeroVironment of Arlington, Virginia will co-design and co-manufacture the helicopters with NASA’s Jet Propulsion Laboratory, whose engineers worked with AeroVironment on Ingenuity.
The delivery sequence is unusual. At Mars, SR-1 Freedom releases a descent stage that is slowed by a parachute and braking rockets, and the helicopters are released in midair to fly to the surface individually. NASA describes that as the first time rotorcraft would be released midair during Mars entry, descent and landing. The page says the landing site has not been chosen, with a landing planned after a second Mars approach in fall 2030.
The Glenn release says the mission will also help build fission-powered systems for NASA’s Moon Base, including operation during lunar darkness and in locations where solar power alone is insufficient. NASA announced SR-1 Freedom at its Ignition event, held on March 24, 2026.
What NASA says about the schedule
Steve Sinacore, the SR-1 Freedom program director, said the contract actions reduce technical risk and help the team maintain momentum toward the 2028 launch, and that they ensure the program is building “the strongest possible foundation.” His comment is a statement of schedule confidence from the person running the program, not a guarantee that the 2028 date will hold.
The details still open are substantial. NASA says launch is planned for late 2028 and a Mars helicopter landing is planned after a second approach in fall 2030, but the landing site is unchosen and the reactor’s operating milestones have not been published in the sources reviewed here. Until the reactor is built and tested, the claim that SR-1 Freedom will be the first fission-powered spacecraft to leave Earth orbit remains NASA’s stated aim, not an accomplished fact.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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