Early Tuesday morning, a softball-sized satellite built by Miami’s City Labs reached low Earth orbit aboard a SpaceX Falcon 9, becoming the first commercially built spacecraft to carry a nuclear power source and the first commercial nuclear mission cleared under the Federal Aviation Administration’s new launch approval process.
The BOHR satellite — short for Betavoltaic Orbital High-Reliability — flew as one of 81 payloads on SpaceX’s Transporter-17 rideshare mission from Vandenberg Space Force Base in California. It settled into low Earth orbit carrying a tritium-powered battery roughly the size of a pencil eraser that City Labs hopes will open a regulatory and technical door for commercial nuclear spacecraft.
City Labs CEO Peter Cabauy described the launch as a historic step for commercial nuclear power in space. According to City Labs, BOHR demonstrates the readiness of safe, compact, regulatory-approved nuclear power systems for routine commercial deployment.
What actually flew
BOHR is a 1U CubeSat — the smallest standard size in the modular satellite format — and its everyday operations run on solar panels. The nuclear component is a payload, not the primary bus power. City Labs is treating this flight as a technology demonstration, not an operational nuclear satellite in the way that phrase would apply to, say, a Voyager probe.
The power source is a betavoltaic battery. Rather than using heat from radioactive decay, as the plutonium-fueled radioisotope thermoelectric generators on NASA’s deep-space probes do, a betavoltaic device converts beta particles emitted by decaying tritium directly into electricity using a semiconductor. The output is measured in nanowatts to microwatts.
That is a small number. It is enough to keep a low-power sensor alive or a security key alive for years, but nowhere near enough to run a communications satellite, let alone a lunar habitat.
Why tritium, and why now
Tritium is a radioactive isotope of hydrogen with a half-life of about 12 years. Its emissions are weak. The Nuclear Regulatory Commission describes the radiation as a low-energy beta particle similar to an electron that cannot penetrate skin and does not travel far in air. That property is what makes commercial launch approval plausible in the first place.
The batteries are safe enough to ship to a residential address, a distinction from the usual handling regime for nuclear materials, which typically move only between facilities licensed to handle radiation.
The tritium in BOHR’s battery is expected to keep producing usable current for roughly a decade, though City Labs expects to have flight data on the payload’s performance within weeks to months.
The regulatory pathway matters more than the wattage
For the commercial space industry, the significance of BOHR is less about the electricity it produces and more about the paperwork it survived. It is the first commercial nuclear payload authorized under the FAA’s launch approval process implemented following National Security Presidential Memorandum-20, a policy signed on August 20, 2019 that restructured how the U.S. government reviews launches of spacecraft carrying nuclear material.
Before this pathway existed, any nuclear payload effectively required a case-by-case interagency review at the highest levels of government. That worked for the handful of NASA science missions carrying plutonium-238, but it did not scale for a commercial industry that might eventually want to fly hundreds of small nuclear payloads on rideshare missions.
The FAA issued its affirmative payload authorization for BOHR on September 30, 2025, following a safety analysis led by City Labs’ Kevin Makinson and independently validated by Sandia National Laboratories. That authorization is now a template.
Other companies working on radioisotope power for small spacecraft — and there are several — now have a documented example of how the review works, what the FAA required, and what the timeline looks like. For a sector that has spent years arguing that regulatory uncertainty is the biggest obstacle to commercial nuclear power, that is real progress.
The gap between BOHR and a Moon base
Cabauy is candid about the ceiling on betavoltaic technology as it exists today. Nanowatts to microwatts will not run a rover. It will not run a radio strong enough to reach Earth from the lunar south pole. It will not keep astronauts warm through a 14-day lunar night.
What it can do is keep a sensor node alive in a permanently shadowed crater — the kind of environment where solar panels are useless and chemical batteries freeze. NASA has been working with City Labs on exactly that application, exploring tritium power sources for instruments in the shadowed regions near the Moon’s poles that are of increasing interest for water ice extraction.
The company is also developing heat-producing versions of the technology, which Cabauy said can generate tens of watts of thermal output — closer to what small lunar surface missions actually need. That figure is still an order of magnitude short of what a crewed base would draw, which is why NASA is separately funding development of full fission surface reactors for the Moon, targeted for deployment by 2030.
National security is the quiet customer
BOHR was funded through a Department of Defense contract, and City Labs holds additional research awards from both the U.S. Air Force Research Laboratory and SpaceWERX. City Labs indicated the mission could serve as a pathfinder for future nuclear-powered spacecraft in both civil and national security applications.
The military interest is straightforward. Low-power, long-life batteries that do not depend on sunlight are useful for classified sensor payloads, secure communications nodes, and any spacecraft that might need to operate in shadowed orbits or drift for years without maintenance. A power source with a decade-long half-life and no moving parts is attractive to mission planners who value reliability above all else.
That dual-use character — civilian science and military utility riding the same regulatory approval — is a familiar pattern in space policy. It is also part of why the FAA pathway matters. Commercial nuclear approval built for a small Miami startup can also be used by a large defense contractor.
What to watch next
City Labs says the tritium payload will report performance data within weeks. That data will determine whether the betavoltaic device behaves in orbit the way it does in the lab — surviving launch vibration, thermal cycling, and the radiation environment of low Earth orbit without measurable degradation. Lockheed Martin ran environmental tests on the company’s tritium devices beginning in 2008, and those units are reportedly still functioning, but ground testing is not orbital operation.
The broader question is whether other companies follow. If a second commercial nuclear payload flies within the next year or two under the same FAA process, BOHR will have done what its builders hoped: turned a one-off approval into a routine one. If it remains the only example, the flight will still stand as a technical first, but the commercial nuclear era will remain theoretical.
Either way, a softball-sized satellite carrying a battery smaller than a paper clip has now flown as the leading edge of a category the space industry has been talking about for decades. The wattage is trivial. The precedent is not.
