US military eyes nuclear thermal rocket for missions in Earth-moon space

DARPA awarded a $14 million task order to help make it happen.

Artist's impression of a spacecraft powered by nuclear thermal propulsion.

Artist’s impression of a spacecraft powered by nuclear thermal propulsion.(Image: © DARPA)

The U.S. military aims to get a nuclear thermal rocket up and running, to boost its ability to monitor the goings-on in Earth-moon space.

The Defense Advanced Research Projects Agency (DARPA) just awarded a $14 million task order to Gryphon Technologies, a company in Washington, D.C., that provides engineering and technical solutions to national security organizations.ADVERTISING

The money will support DARPA’s Demonstration Rocket for Agile Cislunar Operations (DRACO) program, whose main goal is to demonstrate a nuclear thermal propulsion (NTP) system in Earth orbit. 

NTP systems use fission reactors to heat propellants such as hydrogen to extreme temperatures, then eject the gas through nozzles to create thrust. This tech boasts a thrust-to-weight ratio about 10,000 times higher than that of electric propulsion systems and a specific impulse, or propellant efficiency, two to five times that of traditional chemical rockets, DARPA officials wrote in a description of the DRACO program.

Such improvements in propulsion technology are needed for “maintaining space domain awareness in cislunar space — the volume of space between the Earth and the moon,” the DRACO description reads.

Gryphon will work to help make this vision a reality, using the newly awarded $14 million.

“We are proud to support DRACO and the development and demonstration of NTP, a significant technological advancement in efforts to achieve cislunar space awareness,” Gryphon CEO P.J. Braden said in a statement.

DARPA is not alone in seeing great promise in NTP systems. NASA Administrator Jim Bridenstine has lauded the technology’s potential for crewed Mars exploration, for example, noting that NTP-powered spacecraft could get astronauts to the Red Planet in just three to four months — about half the time needed with traditional chemical rockets.

“That is absolutely a game-changer for what NASA is trying to achieve,” Bridenstine said during a meeting of the National Space Council last year. (NASA is working to get astronauts to the Red Planet in the 2030s.) “That gives us an opportunity to really protect life, when we talk about the radiation dose when we travel between Earth and Mars.”