NASA’s SR-1 Freedom mission has reached a new milestone on its nuclear power module. In an article dated October 20, 2026, NASA said that Sierra Lobo Inc. will build the module’s closed Brayton cycle power conversion system, while the Department of Energy’s Idaho National Laboratory designs and develops the fission reactor. NASA calls Space Reactor-1 (SR-1) Freedom humanity’s first fission-powered spacecraft to travel beyond Earth’s orbit, and it is still aiming for a late-2028 launch to Mars. This article is based on NASA’s announcement.
What SR-1 Freedom is meant to do
SR-1 Freedom was announced during NASA’s “Ignition” event. NASA says the mission will demonstrate nuclear electric propulsion in deep space, using electricity from a fission reactor to power the spacecraft’s electric propulsion. On the way, it will deliver a science payload called SkyFall to Mars.
SkyFall is a team of three Mars helicopters that NASA says evolved from the Ingenuity design. According to the agency, they will collect scientific data, demonstrate exploration zones and help identify potential water sources on the Red Planet. For more on how researchers are mapping Mars, see our story on a student who classified 800 million Martian sites.
Inside the SR-1 Freedom nuclear power module
NASA says the nuclear power module sits at the end of the spacecraft’s boom. It has two main parts: a reactor that generates heat through nuclear fission, and a power conversion system that turns that heat into electricity for the spacecraft’s systems and its electric propulsion.
Sierra Lobo’s part is the closed Brayton cycle converter. In general terms, a closed Brayton cycle heats a working gas, runs it through a turbine to drive a generator, then cools and compresses the same gas and sends it around the loop again. NASA says Sierra Lobo’s work will be carried out 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 converter will then be integrated with Idaho National Laboratory’s reactor to complete the module.
Why NASA changed some contracts
To speed up development, NASA says it and its partners “mutually agreed to key contract actions” for the mission. The agency did not detail those actions or their value. Program director Steve Sinacore said they “reduce technical risk and help us maintain momentum toward our 2028 launch,” and that they keep SR-1 Freedom on track while “developing technology extensible to a vibrant space nuclear future.”
How NASA says it is handling nuclear safety
Any nuclear launch raises safety questions, and NASA addresses them directly. It says NASA and DOE build safety standards into the design and development of SR-1 Freedom, including interagency safety reviews, continuous oversight by a NASA chief safety officer, regulatory compliance and a safety design process focused on hazards, failure tolerance and nuclear safety. NASA also says the reactor will remain inactive until the spacecraft has left Earth orbit.
Two ways to read the SR-1 Freedom news
For supporters, this is a long-awaited step. NASA says the mission will pave the way for deeper space exploration and for next-generation fission power systems that could keep NASA’s Moon Base running through long periods of darkness and in places where solar power alone is not enough.
The more cautious view is that a late-2028 launch is not far away for a first-of-its-kind spacecraft, and the update is light on detail. NASA has not shared the reactor’s power output, the cost of the work or what exactly changed in the contracts. Public concern about launching nuclear material is also likely to come up again as the date approaches, even with the safety steps NASA lists.
My view on SR-1 Freedom
As a writer, I feel that fission power is one of the few realistic ways to run serious missions far from the Sun, so it is good to see named partners and hardware responsibilities rather than just a concept. At the same time, I would like NASA to publish more technical and budget detail as the mission moves forward. I am most curious about the three helicopters.
FAQ: SR-1 Freedom
What is SR-1 Freedom?
Space Reactor-1 Freedom is a NASA spacecraft that will demonstrate nuclear electric propulsion in deep space. NASA says it will be the first fission-powered spacecraft to travel beyond Earth’s orbit.
Who is building the nuclear power module?
Sierra Lobo Inc. will provide the closed Brayton cycle power conversion system, and the Department of Energy’s Idaho National Laboratory is designing and developing the fission reactor.
When will SR-1 Freedom launch?
NASA says it will launch in late 2028 and deliver SkyFall, a team of three Mars helicopters, to Mars.