Antares, a nuclear power startup, has announced a significant milestone, securing $96 million in a Series B funding round on December 2nd. This financial boost is earmarked for advancing the development of small nuclear reactors, designed for use in various sectors, including space exploration.
The company reported that the Series B round included $71 million in equity, spearheaded by Shine Capital, with backing from Alt Capital, Caffeinated, FiftyThree Stations, Industrious, and additional investors. Furthermore, Antares secured $25 million in debt financing. This 60-person startup, with operations across California, Idaho, and South Carolina, is focused on creating scalable nuclear reactors for both terrestrial and extraterrestrial applications. The new funding will facilitate the establishment of a California-based factory with the capacity to produce 10 reactors annually, alongside the procurement of essential equipment and uranium fuel.
“We’re months away from our first reactor demonstration, which will validate our control systems and neutronics models, develop our testing facility and fabricate our fuel ahead of our upcoming full-scale electricity-producing prototype in 2027,” said Jordan Bramble, chief executive of Antares, in a statement. This initial reactor demonstration, known as Mark-0, is scheduled to commence testing next year at the Department of Energy’s Idaho National Laboratory. It will contribute to the development of the Mark-1 prototype reactor, slated for 2027.
Antares is also collaborating with NASA on specific aspects of its reactor technology. The company revealed that it conducted thermal and mechanical testing on an electrically heated prototype at Marshall Space Flight Center during the summer. The company anticipates opportunities with both the military and NASA for its microreactors, which are compact, transportable units intended to supply power in remote locations, including space.
Antares has expressed interest in NASA’s Fission Surface Power (FSP) program, which seeks to develop a reactor capable of generating at least 100 kilowatts on the lunar surface. “This program’s requirements align with our manufacturing core competencies and design,” Bramble stated regarding FSP. “We believe nuclear power is critical to enabling a space-based industrial economy.”
NASA unveiled new plans in August for developing nuclear reactors for lunar deployment. A directive signed by Acting Administrator Sean Duffy called for collaborations with private entities to foster the development of a reactor ready for deployment on the moon by 2030. This directive followed a report from Idaho National Laboratory that advocated for accelerated development of nuclear power and propulsion technologies. NASA issued a draft solicitation in late August, called an Announcement for Partnership Proposals, for the program. It called for using Space Act Agreements to support reactor development. Companies would own the reactors they develop and sell power to NASA or other customers through services contracts. NASA had planned to release a final version of the solicitation in early October, but the timeline was delayed by the six-week government shutdown that began Oct. 1. In a Nov. 19 procurement notice, NASA said it would issue a second draft Dec. 5, with the final version now expected in early 2026.