NASA joins forces with DARPA on nuclear rocket program

The Defense Advanced Research Projects Agency has taken on NASA as a partner for a project aimed at demonstrating a nuclear-powered rocket that could someday send astronauts to Mars.

DARPA had already been working with commercial partners — including Blue Origin, the space venture created by Amazon founder Jeff Bezos, as well as Seattle-based Ultra Safe Nuclear Technologies, or USNC-Tech — on the Demonstration Rocket for Agile Cislunar Operations program, also known as DRACO. USNC-Tech supported Blue Origin plus another team led by Lockheed Martin during an initial round of DRACO design work.

Now DARPA and NASA will be working together on the next two rounds of the DRACO program, which call for a commercial contractor to design and then build a rocket capable of carrying a General Atomics fission reactor safely into space for testing. The current plan envisions an in-space demonstration in fiscal year 2027.

“With the help of this new technology, astronauts could journey to and from deep space faster than ever – a major capability to prepare for crewed missions to Mars,” NASA Administrator Bill Nelson said today in a news release. 

NASA’s deputy administrator, Pam Melroy, noted that the space agency has had a “long history of collaborating with DARPA on projects that enable our respective missions, such as in-space servicing.”

“Expanding our partnership to nuclear propulsion will help drive forward NASA’s goal to send humans to Mars,” she said.

In a nuclear thermal rocket, or NTR, the engine’s reactor heats propellant to extreme temperatures to produce thrust. DARPA says an NTR would have a thrust-to-weight ratio 10,000 times greater than electric propulsion systems, and a specific impulse that’s two to five times more efficient than traditional chemical propulsion systems.

“Since the NTR uses propellant more efficiently, it offers more aggressive trajectories and creative burn profiles to move heavy cargo more quickly in the cislunar domain as compared to today’s in-space propulsion methods,” Tabitha Dobson, DARPA program manager for DRACO, said in a news release.

NASA’s Space Technology Mission Directorate will lead technical development of a nuclear thermal engine that would be integrated with DARPA’s experimental spacecraft. DARPA is acting as the contracting authority for the development of the entire rocket stage and the engine, which includes the reactor. The U.S. Space Force has signaled its support for DRACO with the intent to provide the launch for the demonstration mission.

The DRACO engine would use high-assay, low-enriched uranium instead of highly enriched uranium, and DARPA said the engine’s fission reaction would be turned on only once it reaches space.

DARPA spokesman Randy Atkins said the contract for the next phase of the DRACO program is due to be awarded in March. “We can’t yet comment on who may or may not have bid for Phase 2,” he told GeekWire in an email.

DRACO isn’t the only program supporting the development of nuclear thermal propulsion systems. In partnership with Blue Origin and other companies, USNC-Tech won a $5 million contract from NASA and the Department of Energy in 2021 to work on a longer-range nuclear propulsion effort called the Power Adjusted Demonstration Mars Engine, or PADME.