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. Announced during NASA’s “Ignition” event, this mission will demonstrate nuclear electric propulsion in deep space, and progress is underway on its key element: the nuclear power module. 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. 

“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.” 

Sierra Lobo Inc. will provide the nuclear power module’s closed Brayton cycle power conversion system, which converts thermal energy from its fission reactor into electrical power needed for SR-1 Freedom’s nuclear electric propulsion demonstration. 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.

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 to complete the nuclear power module. 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. In addition, the nuclear reactor portion of SR-1 Freedom will remain inactive until the spacecraft leaves Earth orbit.

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. 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.

For information about SR-1 Freedom, visit:

https://www.nasa.gov/mission/space-reactor-1-freedom/

If you’ve ever had your car start sluggishly, or not at all, on a particularly frigid winter morning, you know standard batteries do not like extreme cold. That’s why NASA researchers are working to develop a battery that could function in the brutal cold of the Moon’s South Pole, where nighttime temperatures plunge to minus 328 degrees Fahrenheit (minus 200 Celsius). 

For future lunar operations, a battery will need to work immediately when warmed up and be able to power everything from an astronaut’s emergency kit to a rover capable of exploring the Moon’s darkest craters — all without posing a fire hazard. 

A team of NASA researchers is working to make all that happen. The project is called Solid Power for Extreme Environment Adaptability and Resilience in Space (SPEARS), and it could provide NASA with an important tool to help power humanity’s sustained presence on the Moon through the Artemis campaign. 

“Batteries have become an important part of our lives here on Earth, which enable our laptops, cell phones, power tools, and even our vehicles,” said Donald Dornbusch, principal investigator for SPEARS at NASA’s Glenn Research Center in Cleveland, where the project is led. “We will need them on the Moon, too, and these batteries will be required to operate reliably and safely in this harsh environment. That’s why we’re working on this technology.” 

Splashy problem, solid solution

Traditional lithium-ion batteries like those in your cell phone and laptop have a critical weakness: they rely on liquid electrolytes. Cool a conventional battery to the Moon’s nighttime temperatures, and that liquid would freeze, potentially damaging the battery. Heat it up too much — say, to daytime lunar temperatures of 212 F (100 C) — and it won’t work until cooled. Expose the liquid to the vacuum of space, and it evaporates. 

SPEARS batteries solve these problems by replacing the liquid electrolyte with a solid ceramic- or polymer-based material. This change could unlock several advantages. First and foremost, they could operate in the heat and extreme cold. 

During recent thermal vacuum testing at NASA’s Langley Research Center in Hampton, Virginia, small prototype battery cells operated well up to 176 F (80 C), down to minus 76 F (minus 60 C), and with slightly reduced performance down to minus 112 F (minus 80 C). 

“We proved for the first time that these cells can work down to minus 80 degrees Celsius,” said Yi Lin, SPEARS testing and research lead at NASA Langley.  

Lin also said he’s confident they can improve performance and maybe even expand that range in coming years. 

The batteries need to remain reliable through exposure to the Moon’s wild temperature swings between day and night. The thermal vacuum testing showed that after exposure to temperature extremes from 212 F (100 C) to minus 274 F (minus 170 C), SPEARS batteries don’t sustain damage.  

Not even solid-state batteries will function while they’re at a temperature as low as minus 274 F, but because solid electrolytes don’t freeze like a liquid, the batteries can survive the extreme low temperatures.  

In order to get the batteries working again after exposure to such cold, small heaters come into play. SPEARS batteries wouldn’t need to be kept warm all the time, just warmed up to operational temperature. That could reduce the need for heavy thermal management systems in spacecraft and lunar habitats, allowing for lighter designs, lower costs, and longer mission durations. 

Power for Moon, Earth

The applications for these solid-state batteries are nearly limitless, from small tools like drills that must operate in shadowed lunar craters, to rovers and emergency power packs for astronauts. They also could provide power solutions for long-duration scientific instruments. 

“We can tune the chemistry by using different electrode materials,” said Lin. “Just like the chemistry in your earbuds is different from the chemistry in your phone, which is different from the chemistry in your car, all these chemistries can still function with a solid electrolyte. We can tune for energy, tune for power, tune for durability, depending on the application.” 

While SPEARS is designed for space, the technology could be spun off into Earth-based applications. In fact, SPEARS evolved out of a previous battery project Lin and Dornbusch worked on that focused on aeronautic applications. 

“The potential market for solid-state batteries is very broad,” said Ji Su, a polymer materials scientist and the task lead at NASA Langley. “Automobiles, cell phones, communication devices, drones — anything that needs a portable power supply.” 

The SPEARS project began in 2026 with funding through the Advanced Research and Technology division within the agency’s Research and Technology Mission Directorate. The project is set to focus on technology development in its first stages before potentially shifting toward commercial collaboration. NASA’s Ames Research Center in California’s Silicon Valley is working to develop flight hardware such as test boards and electronics to help prepare the SPEARS batteries for spaceflight and test them in space environments.