NASA advances development of fission-powered SR-1 Freedom spacecraft for Mars mission

Contract actions for nuclear power module move forward as agency prepares for 2028 launch

By LineZotpaper

Published20 October 2026

Read Time2 min

NASA announced progress on the Space Reactor-1 (SR-1) Freedom, the first fission-powered spacecraft designed to operate beyond Earth orbit. Key contract actions have been taken to advance the development of the nuclear power module, a critical element of the spacecraft's propulsion and power systems. The mission is scheduled for launch in late 2028, when SR-1 Freedom will deliver the SkyFall science payload, a trio of Mars helicopters evolved from the Ingenuity design, to collect scientific data, identify potential water sources, and demonstrate exploration zones.

NASA’s Space Reactor-1 (SR-1) Freedom will be humanity’s first fission-powered spacecraft to travel outside Earth’s orbit. Announced during the agency's Ignition event, the mission aims to demonstrate nuclear electric propulsion in deep space.

Progress is now underway on the nuclear power module, which sits at the end of the spacecraft’s boom and contains both the fission reactor and a power conversion system. Sierra Lobo Inc. has been selected to provide the module’s closed Brayton cycle power conversion system, which will convert thermal energy from the reactor into electrical power for the spacecraft’s systems and electric propulsion. The work will be performed under the Space Flight Systems Development and Operations Contract III, awarded in 2024, at NASA’s Glenn Research Center in Cleveland.

The fission reactor itself is being designed and developed by the Department of Energy’s Idaho National Laboratory. NASA and DOE are incorporating thorough safety standards through interagency reviews, continuous oversight by a NASA chief safety officer, and a rigorous design process focusing on hazards and failure tolerance. The nuclear reactor will remain inactive until the spacecraft has left 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.”

The mission is intended to pave the way for deep space exploration and next-generation fission-powered systems, including those that could keep NASA’s Moon Base operating through periods of darkness and in locations where solar power alone is insufficient.

Analysis

Why This Matters

SR-1 Freedom represents a major step toward practical nuclear propulsion for deep space, potentially reducing travel times and enabling more ambitious missions to Mars and beyond.
Success would demonstrate that fission reactors can operate safely and reliably beyond Earth orbit, opening the door for sustained operations on the Moon and elsewhere.
The technology could eventually power habitats, life support, and other infrastructure in locations where solar energy is scarce, such as the lunar poles or the outer solar system.

Background

NASA has used nuclear power in space for decades, primarily through radioisotope thermoelectric generators (RTGs) that convert heat from decaying plutonium into electricity. However, SR-1 Freedom will be the first spacecraft to carry a fully functional fission reactor beyond Earth orbit, generating far more power than RTGs alone. The project is a collaboration between NASA and the Department of Energy, which handles the reactor design through Idaho National Laboratory. The SkyFall payload, consisting of three Mars helicopters, builds on the pioneering flights of NASA's Ingenuity helicopter, which flew 72 times on Mars between 2021 and 2024.

Key Perspectives

NASA: The agency sees fission power as essential for expanding the reach and capability of human and robotic exploration. Programme director Steve Sinacore emphasised that the contract actions reduce technical risk and strengthen collaboration while laying groundwork for a broader space nuclear future. Department of Energy: DOE's Idaho National Laboratory is contributing its expertise in nuclear reactor design and safety. The partnership ensures that the reactor meets both spaceflight and nuclear regulatory standards. Critics and safety watchdogs: Some observers may raise concerns about launching nuclear material, even an inactive reactor, into Earth orbit. NASA and DOE have put in place interagency safety reviews, continuous oversight, and a design that keeps the reactor inert until the spacecraft is safely away from Earth.

What to Watch

Completion and testing of the closed Brayton cycle power conversion system, which is a key technology demonstration.
Integration of the nuclear power module with the rest of the spacecraft and any schedule adjustments leading up to the late 2028 launch window.
The performance of the SkyFall helicopters once on Mars, as they will rely on data returned by SR-1 Freedom's own systems during transit.

Sources

NASA’s SR-1 Freedom Advances with Progress on Nuclear Power Module · NASA

Checked

12 claims in this story checked against 1 source: 10 supported.

Show each claim

SupportedNASA is advancing development of the fission-powered SR-1 Freedom spacecraft for a Mars mission.NASA: “Destined for Mars and beyond, NASA’s Space Reactor-1 (SR-1) Freedom will be humanity’s first fission-powered spacecraft to travel outside Earth’s orbit.”
Partly supportedContract actions are advancing the nuclear power module as NASA prepares for a 2028 launch.NASA: “To expedite development of the spacecraft, NASA and its partners have mutually agreed to key contract actions that will advance the SR‑1 Freedom mission.”
Partly supportedSR-1 Freedom is the first fission-powered spacecraft designed to operate beyond Earth orbit.NASA: “Space Reactor-1 Freedom will be the first spacecraft ever to demonstrate fission power beyond Earth’s orbit”
SupportedThe mission is scheduled to launch in late 2028 and deliver SkyFall, three Mars helicopters evolved from Ingenuity, to collect data, identify potential water sources and demonstrate exploration zones.NASA: “Launching in late 2028, SR‑1 Freedom will deliver the SkyFall science mission, a team of three Mars helicopters evolved from the Ingenuity design, to collect scientific data, demonstrate exploration zones, and identify potential water sources.”
SupportedSteve Sinacore said the contract actions reduce technical risk, maintain momentum toward the 2028 launch and strengthen collaboration across partners.NASA: ““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.”
SupportedSteve Sinacore said the actions keep SR-1 Freedom on track and help build a foundation for NASA’s first fission-powered voyage beyond Earth orbit and future space nuclear technology.NASA: ““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.””
SupportedSierra Lobo Inc. will provide the module’s closed Brayton cycle power conversion system.NASA: “Sierra Lobo Inc. will provide the nuclear power module’s closed Brayton cycle power conversion system”
SupportedThe work will be performed under a contract awarded in 2024 at NASA’s Glenn Research Center in Cleveland.NASA: “The work will be conducted under the Space Flight Systems Development and Operations Contract III, awarded in 2024 , to support spaceflight hardware design, development, testing, and operations at NASA’s Glenn Research Center in Cleveland.”
SupportedThe fission reactor is being designed and developed by the Department of Energy’s Idaho National Laboratory.NASA: “The power conversion system will be integrated with the fission reactor, which is being designed and developed by the Department of Energy (DOE)’s Idaho National Laboratory”
SupportedNASA and DOE are using interagency reviews, safety oversight and a rigorous design process focused on hazards and failure tolerance.NASA: “NASA and DOE incorporate thorough safety standards throughout the design and development of the SR-1 Freedom spacecraft, including 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.”
SupportedThe reactor will remain inactive until the spacecraft has left Earth orbit.NASA: “In addition, the nuclear reactor portion of SR-1 Freedom will remain inactive until the spacecraft leaves Earth orbit.”
SupportedThe mission is intended to pave the way for next-generation fission-powered systems that could keep NASA’s Moon Base operating through darkness and where solar power is insufficient.NASA: “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.”