Nuclear Revival: Antares Secures $161M DoD Space Reactor Contract

Terminal Access: Orbital Nuclear Propulsion

Energy scarcity in orbit is nearing a critical inflection point. According to Payload, the U.S. Department of Defense has awarded nuclear startup Antares a $161 million contract to accelerate the development of space-rated microreactors. This marks the largest DoD space nuclear award to date, signaling a shift toward high-energy orbital maneuvers.

Antares is tasked with a rigorous three-stage roadmap: ground-demonstrating the R1-S (a heat-pipe microreactor variant), integrating the system with a spacecraft for flight certification, and eventually powering an operational ground-to-space asset with the Mark-1 reactor. The company targets a six-month operational run in orbit by 2027.

Strategic Energy Superiority

The move follows Antares’ recent success under the Department of Energy’s Reactor Pilot Program, where its Mark-0 prototype became the first private advanced reactor to achieve criticality. Bolstered by a $470 million Series C round in July, the firm is positioning its technology as the backbone for next-generation Space Force requirements.

Solar arrays, while reliable, cannot sustain the heavy compute loads, directed energy systems, or continuous electromagnetic warfare assets required for modern defense. Nuclear fission offers "maneuver without regret," freeing spacecraft from the power-rationing constraints of battery and solar cycles.

Multi-Domain Expansion

This award is part of a broader DoD push. Antares is already engaged in the Army’s Project Janus for on-base power and the Air Force’s DIU initiative. While the space nuclear market remains in its infancy, the U.S. government is aggressively targeting 2028 for orbital deployment and 2030 for lunar surface operations to ensure American space dominance.

Source: Payload