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Company Size
51-200
Company Stage
Grant
Total Funding
$757M
Headquarters
Los Angeles, California
Founded
2023
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Louisiana-based nuclear microreactor startup Antares has secured a $161 million Strategic Breakthrough award from the US Space Force to develop nuclear power systems for future space missions. The funding represents one of the largest current US defence investments in space nuclear power. Antares will first demonstrate its R1-S reactor design on the ground before integrating it with a spacecraft for flight certification. The company plans to begin testing its Mark-1 reactor in 2027, which will operate for over six months during the test campaign. The startup achieved a significant milestone in June when its Mark-0 microreactor reached initial criticality at Idaho National Laboratory, making Antares the first private company to achieve advanced-reactor criticality under the Department of Energy's Reactor Pilot Program. The US has not operated a nuclear reactor in space since NASA's SNAP-10A mission in 1965.
Antares wins $161 million Space Force award for nuclear reactor demonstration. September 11, 2026 Rendering of a nuclear-powered spacecraft in Earth orbit Antares has been selected for a $161 million Strategic Breakthrough award to demonstrate nuclear power technology for space, giving the nuclear energy company a path to test its R1-S reactor on the ground and integrate the system with a spacecraft ahead of flight certification and launch. The award was made through the Office of the Assistant Secretary of the Air Force for Space Acquisition and Integration and represents the largest Department of War award for space nuclear power to date, according to Antares. Under the program, Antares will conduct a nuclear ground demonstration of its R1-S system before integrating the reactor with a spacecraft for flight certification. The work moves the company's compact fission technology toward an operational space mission rather than limiting development to reactor testing. Antares will also use Mark-1, its electricity-producing reactor, to power an operational ground-to-space asset. Testing of Mark-1 is scheduled for 2027, creating another step in validating how the company's reactor and power-conversion technologies perform as an integrated energy system. "This partnership with the Space Force turns that long-held vision into a codified space mission," CEO and co-founder Jordan Bramble said. "Fission will unlock strategic capabilities that are impossible today." The program addresses one of the central infrastructure constraints for more power-intensive spacecraft: generating reliable electricity while maintaining sufficient propulsion capacity for maneuvering. Nuclear fission could provide continuous power for systems with heavier computing requirements and other high-demand payloads without depending on conventional spacecraft power architectures alone. Antares is targeting applications including advanced computing, directed-energy systems and electromagnetic warfare. The company also sees nuclear power as a way to reduce propulsion-related operational constraints, potentially allowing spacecraft to conduct more dynamic maneuvers while maintaining power for onboard systems. The award builds on a reactor milestone Antares reached earlier this year. On June 4, 2026, its Mark-0 microreactor achieved initial criticality at Idaho National Laboratory under Department of Energy authorization. Antares said the milestone made it the first private company to bring an advanced reactor to criticality through the DOE Reactor Pilot Program. The next stage centers on producing usable electricity. Antares plans to operate its Mark-1 reactor for more than six months in 2027, integrating it with the company's nitrogen closed Brayton cycle power-conversion system. That configuration is designed to move development beyond reactor physics and demonstrate an integrated system capable of converting reactor heat into electricity. Successfully coupling the reactor with power conversion is an important operational requirement for both terrestrial and space applications. The company's development sequence moves from Mark-0 criticality to extended Mark-1 electricity production, followed by the R1-S ground demonstration and spacecraft integration required for a potential flight mission. The Strategic Breakthrough program also aligns with federal plans to accelerate deployment of nuclear power beyond Earth. Antares said the award supports goals established by Executive Order 14369, "Ensuring American Space Superiority," and the National Initiative for American Space Nuclear Power established through NSTM-3. Those policies call for nuclear reactors to be launched into space as early as 2028 and deployed on the lunar surface by 2030. Founded in 2023, Antares is developing compact nuclear microreactors for defense and space applications. The company has raised more than $600 million and expects initial production deployments at U.S. military installations beginning in 2028. Antares operates facilities in Torrance, California; Idaho Falls, Idaho; and Aiken, South Carolina. The $161 million award adds a dedicated space mission to a development program that is now moving from reactor criticality toward electricity generation, spacecraft integration and eventual deployment.
Antares wins $161M award for space nuclear power. Friday September 11, 2026 Waxing Crescent Payload in your inbox. In-depth research, exclusive data, and expert analysis on the business and policy of space. Get ahead of the competition.
The Army just put A price on five nuclear microreactors for U.S. Bases. The Army just put a price on its plan to install nuclear microreactors at five military bases across the eastern U.S. - $2.2 billion. The payout flows to five nuclear energy players, including BWX Technologies and Westinghouse Government. Microreactors can be a thousand times smaller than conventional reactors, with correspondingly small footprints that lend themselves to factory assembly, delivery by truck or air, and flexible deployment. They're part of the Trump administration's push to quench surging electricity demand, much of it AI-driven, with nuclear power. How This Uranium Enrichment Technology Aims To Solve The Nuclear Fuel Bottleneck For Big Tech AI data centers require 24/7 power, a demand only nuclear energy can meet. But the industry faces a major hurdle: fuel supply. LIS Technologies CEO Jay Yu breaks down the shift toward domestic uranium enrichment and the roadmap to securing America's energy future. How This Uranium Enrichment Technology Aims To Solve The Nuclear Fuel Bottleneck For Big Tech See All Videos Microreactors are a category of especially petite small modular reactors (SMRs), defined by the Energy Information Administration as ranging from 1 to 20 megawatts of output. The low end of that range is enough to power hundreds of homes at peak demand. None of these development-stage reactors is yet ready for commercial use or military deployment. BWX, Westinghouse land contracts. BWX Technologies (BWXT) is the sole publicly traded vendor selected by the Army. It's set to design and deploy a microreactor for Kentucky's Fort Campbell. Westinghouse Government - a unit of Westinghouse Electric, a joint venture owned by Brookfield Renewable Partners (BEP) and Cameco Corp. (CCJ) - is slated to do the same for New York's Fort Drum. BWX traded close to 1% lower Monday afternoon. Shares are down 12% year to date, after rallying 54% in 2025. Cameco stock shed more than 2%, narrowing its 2026 gain to just under 7%. It rocketed 78% in 2025. Private firms Radiant Industries, General Atomics Electromagnetic Systems and Antares Nuclear will develop units in Georgia, Texas and North Carolina. Each vendor is contracted to design, own, deploy and operate their respective microreactors. They're also responsible for handling nuclear waste disposal within two years, the New York Times reports. IBD newsletters. Get exclusive IBD analysis and actionable news daily. Several SMRs have so far successfully produced stable chain reactions during the second Trump administration. None operate commercially in the U.S. to date. There are dozens of SMRs in various stages of development and deployment across the U.S. "With the private sector funding expected along with these government dollars, the Army expects more than 20 total nuclear microreactors will be built and operated across Department of War installations," the military said in a statement. Microreactors: opportunities and challenges. Microreactors rely on nuclear fission to generate heat and turn turbines with steam. Their primary perk is modularity, which means developers can build and ship them, while buyers could stack modules as needed to meet rising energy demand. The extra small reactors are "(price-competitive) with technologies with similar scale and application," according to a 2021 review published in the journal Progress in Nuclear Energy. But microreactors still yield radioactive waste and face strict regulatory hurdles. Specifically, the availability of the specialized HALEU fuel remains a critical bottleneck for the technology. The Army expects to secure enough high-assay low-enriched uranium (HALEU) for about 20 microreactors, a spokesperson told the New York Times. Beyond that, the Energy Department is attempting to kick-start a domestic supply chain for the fuel through purchase agreements. Follow Harriet Weber on LinkedIn and Bluesky. Find her on Signal: hew.04. YOU MAY ALSO LIKE:
US Army taps 5 firms to build on-base microreactors in nuclear energy push. Eve Sampson Wed, August 26, 2026 at 1:48 PM PDT The Army is investing billions of dollars to bring nuclear power to military bases, selecting five companies to build nuclear microreactors at installations across the U.S., the service announced Wednesday in collaboration with the Pentagon's Defense Innovation Unit. Antares Nuclear will develop a microreactor - or microreactors - at Fort Bragg, North Carolina; BWXT Advanced Technologies at Fort Campbell, Kentucky; General Atomics Electronagnetic Systems at Fort Hood, Texas; Radiant Industries at Fort Benning, Georgia; and Westinghouse Government Services at Fort Drum, New York. The service said it expects to field more than 20 microreactors across Department of Defense installations. The agreements, worth up to $2.2 billion combined, mark a step in the Army's Janus program, an initiative that aims to introduce microreactors to power installations independently rather than relying on civilian electrical grids. The Army introduced the program in 2025 after an executive order called for the military to speed up its integration of nuclear power, with the goal of having an operational reactor at a military base by Sept. 30, 2028. "Awarding these contracts accelerates our ability to deliver safe, reliable baseload power directly to our installations," Secretary of the Army Dan Driscoll said in a release. "We are building the energy resilience necessary to project combat power globally, without relying on potentially vulnerable external grids." The reactors will be contractor-owned and operated, the Army said, adding that vendors will only be paid if they hit technical milestones. Each installation will remain on the commercial power grid, officials said at a Wednesday media briefing, and the reactors are not intended to power the base completely. The Janus program follows the Pentagon's 2022 announcement of "Project Pele," which sought to develop a portable 40-ton nuclear reactor that could generate one to five megawatts of power. None of the base's future reactors use highly enriched - or weapon's grade - uranium, according to Jeff Waksman, principal deputy assistant secretary of the Army for Installations, Energy and Environment. In the briefing, he said the push toward nuclear energy stemmed from the nation's growing awareness of security risks and reliance on fossil fuel. "Unlike in prior conflicts, we now know that our domestic electric grid is potentially at risk in a conflict," he said during the briefing. "We also know that we will not necessarily be able to move fossil fuels easily wherever we need them to go. Right now, all critical infrastructure that the Army has is backed up by some form of liquid fossil fuel, primarily diesel." Outside of the continental U.S., the threat remains, he said, as U.S. interests often rely on international ships. "We're often dependent. In a lot of our Pacific islands, we're dependent on foreign-shipped fuel from foreign-flagged vessels, and that doesn't give us a lot of comfort if there were to be a future conflict," he continued. Nuclear waste will not be stored on bases long-term, Waksman said. The effort comes as the U.S. is currently at war with Iran, with both countries insisting that the Strait of Hormuz, in which around one-fifth of the global oil supply passes, is under their respective control. The war has driven up energy costs worldwide. Installations were chosen based on a multilayered analysis including mission-set, power grid feasibility, environmental concerns and safety, according to Brandon Cockrell, deputy assistant secretary of the Army for Energy & Sustainability. He also nodded to the bases' role in deploying troops. "It's really difficult to look across the five and not draw the immediate conclusion that this is a direct link to power projection," he said, adding that such a component was part of the assessment. "This is because we have to be able to project power. We have to be able to meet the Army's mission if there is any vulnerabilities in the grid." In Nov. 2025, the Army said it was also considering Fort Wainwright, Holston Army Ammunition Plant, Joint Base Lewis-McChord and Redstone Arsenal. Energy resiliency has become an increasingly important facet of technology development across the Army, which has pitted three contractors against each other to build a light tactical vehicle capable of producing large amounts of energy to power counter-drone systems, electronic warfare and directed energy weapons. The Army did not disclose the contract amounts for each nuclear microreactor company. Radiant, which has a contract tied to a Georgia base, disclosed that it secured an agreement totaling $750 million for 15 Kaleidos nuclear microreactors, which are currently undergoing testing at the Idaho National Laboratory DOME facility. In a Wednesday release, the company said that the 1-megawatt microreactors would be transportable and "plug-in ready." General Atomics, which is tied to a Texas base, advanced its Tactical Energy System, or GA-TES, that has a baseline output of 5 megawatts and can scale up to 20 megawatts, a Wednesday announcement said. The GA-TES is transportable by rail or truck.