NASA Advances Nuclear Power Module for SR-1 Freedom Mars Mission

NASA has agreed to key contract actions that advance work on the nuclear power module for SR-1 Freedom, the first spacecraft intended to demonstrate fission power beyond Earth's orbit. The agency says the moves reduce technical risk and keep the mission on course for a late 2028 launch to Mars.

Space Reactor-1 Freedom was announced during NASA's "Ignition" event and will demonstrate nuclear electric propulsion in deep space. Progress is now underway on the mission's central element, the nuclear power module, with NASA and its partners mutually agreeing to contract actions to expedite development of the spacecraft.

Sierra Lobo Inc. will provide the module's closed Brayton cycle power conversion system, which converts thermal energy from the fission reactor into the electrical power needed for the nuclear electric propulsion demonstration. The work falls under the Space Flight Systems Development and Operations Contract III, awarded in 2024, which supports spaceflight hardware design, development, testing, and operations at NASA's Glenn Research Center in Cleveland. The power conversion system will be integrated with a fission reactor being designed and developed by the Department of Energy's Idaho National Laboratory to complete the nuclear power module, which sits at the end of the spacecraft's boom.

NASA and DOE incorporate safety standards throughout design and development, including interagency safety reviews, continuous oversight by a NASA chief safety officer, regulatory compliance, and a rigorous safety design process focused on hazards, failure tolerance, and nuclear safety. The nuclear reactor will remain inactive until the spacecraft leaves Earth orbit.

"These contract actions not only reduce technical risk and help us maintain momentum toward our 2028 launch, but they also strengthen collaboration across our partners," said Steve Sinacore, SR-1 Freedom program director. "These actions keep SR-1 Freedom on track and ensure we're building the strongest possible foundation for NASA's first fission-powered voyage beyond Earth orbit while developing technology extensible to a vibrant space nuclear future."

Launching in late 2028, SR-1 Freedom will deliver the SkyFall science mission, a team of three Mars helicopters evolved from the Ingenuity design. The payload will collect scientific data, demonstrate exploration zones, and identify potential water sources. NASA states the mission will pave the way for deep space exploration and next-generation fission-powered systems designed to keep NASA's Moon Base operating through periods of darkness and in locations where solar power alone is not sufficient.

Next milestones include integrating the Sierra Lobo power conversion system with the Idaho National Laboratory fission reactor to complete the nuclear power module ahead of the targeted late 2028 launch.