NASA advances SR-1 Freedom nuclear power module for 2028 Mars mission

NASA has announced progress on the nuclear power module for its Space Reactor-1 (SR-1) Freedom mission, a spacecraft designed to be the first to demonstrate fission power beyond Earth’s orbit. The mission, destined for Mars, will also deliver a science payload known as SkyFall. To expedite development, NASA and its partners have mutually agreed to key contract actions.

Contract Actions and Partnerships

Sierra Lobo Inc. will provide the closed Brayton cycle power conversion system for the nuclear power module. This system converts thermal energy from the fission reactor into electrical power required for the spacecraft’s nuclear electric propulsion demonstration. The work will be conducted under the Space Flight Systems Development and Operations Contract III, which was awarded in 2024 to support spaceflight hardware design, development, testing, and operations at NASA’s Glenn Research Center in Cleveland.

The fission reactor itself is being designed and developed by the Department of Energy (DOE)’s Idaho National Laboratory. Once integrated with the power conversion system, these components will complete the nuclear power module, which is located at the end of the spacecraft’s boom.

Safety and Development Timeline

Steve Sinacore, SR-1 Freedom program director, stated that the new contract actions are critical for the mission's schedule. "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 Sinacore. He added that the 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."

NASA and the DOE incorporate thorough safety standards throughout the design and development process. These measures include interagency safety reviews, continuous oversight by a NASA chief safety officer, regulatory compliance, and a rigorous safety design process focusing on hazards, failure tolerance, and nuclear safety. According to NASA, the nuclear reactor portion of SR-1 Freedom will remain inactive until the spacecraft leaves Earth orbit.

Mission Objectives

SR-1 Freedom is scheduled to launch in late 2028. The mission will deliver the SkyFall science mission, which consists of a team of three Mars helicopters evolved from the Ingenuity design. These helicopters will collect scientific data, demonstrate exploration zones, and identify potential water sources on Mars.

NASA states that the mission will pave the way for deep space exploration and next-generation fission-powered systems. These systems are designed to keep NASA’s Moon Base operating through periods of darkness and in locations where solar power alone is not sufficient.

Why it matters

The advancement of the SR-1 Freedom nuclear power module marks a significant step toward demonstrating nuclear electric propulsion in deep space. By successfully integrating the Sierra Lobo power conversion system with the DOE's Idaho National Laboratory reactor, NASA aims to validate technology that could support future long-duration missions to Mars and sustained operations on the Moon, where solar energy is intermittent.

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Sources

• nasa.gov: NASA’s SR-1 Freedom Advances with Progress on Nuclear Power Module - NASA

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