The US has not operated a nuclear reactor in space since 1965. Antares now wants to change that with a $161 million defense award.<\/p>\n
The nuclear microreactor startup has won a Strategic Breakthrough award from the US Space Force. It will use the funding to advance nuclear power systems for future space missions.<\/p>\n
The award ranks among the largest current US defense investments in space nuclear power. It also gives Antares a path from reactor testing on Earth toward a potential flight system.<\/p>\n
The program could eventually give spacecraft a persistent source of electricity. That matters as military satellites demand more computing power and advanced onboard systems.<\/p>\n
Reactor built for space<\/p>\n
Antares will first demonstrate its R1-S reactor design on the ground. Engineers will then integrate the system with a spacecraft for flight certification before launch.<\/p>\n
The R1-S uses heat pipes to move heat away from its nuclear core. That design avoids many mechanical components found in conventional cooling systems.<\/p>\n
Antares also plans to use its Mark-1 reactor for an operational ground-to-space system. Testing is scheduled to begin in 2027.<\/p>\n
Mark-1 will generate electricity through a closed Brayton cycle power system. Antares expects the reactor to operate for more than six months during that test campaign.<\/p>\n
The company sees nuclear power as more than an energy source. A reactor could give spacecraft greater freedom to maneuver without quickly exhausting limited power reserves.<\/p>\n
Continuous electrical output could also support heavier computing workloads and directed-energy systems. Those capabilities could become increasingly important as military operations move into more contested orbital environments.<\/p>\n
Antares already crossed milestone<\/p>\n
Antares reached a major reactor milestone earlier this year. Its Mark-0 microreactor<\/a> achieved initial criticality at Idaho National Laboratory on June 4.<\/p>\n Initial criticality means the reactor sustained a self-supporting nuclear fission chain reaction. The Department of Energy authorized the test under its Reactor Pilot Program.<\/p>\n That milestone made Antares the first private company to achieve advanced-reactor criticality under the program. It also gave the startup practical operating experience before its larger Mark-1 test. The timing adds momentum to the space effort. Antares raised $470 million in a Series C financing round in July.<\/p>\n CEO and co-founder Jordan Bramble said<\/a> the company has pursued space applications since its founding. He described the award as the point where that ambition became an official mission.<\/p>\n The broader US effort also has a firm policy target. Executive Order 14369 calls for nuclear reactors in space as early as 2028.<\/p>\n A separate national initiative calls for nuclear power on the lunar surface by 2030. Those goals would require reliable systems that can survive launch and operate far from conventional power infrastructure.<\/p>\n Sixty-year gap<\/p>\n The US has only flown one nuclear reactor in space. NASA launched SNAP-10A in 1965 as an experimental nuclear power system.<\/p>\n More than six decades later, Antares<\/a> is pursuing a very different generation of reactor. Its systems target military spacecraft that need sustained electrical power and greater operational flexibility.<\/p>\n