SpaceX and City Labs Launch First Commercial Nuclear Satellite

What Happened?

On July 7, 2025, a SpaceX Falcon 9 rocket lifted off from Vandenberg Air Force Base in California carrying 81 payloads, including the BOHR (Betavoltaic Orbital High-Reliability) satellite developed by City Labs. It is the first commercial nuclear satellite ever launched. BOHR is a CubeSat that uses tritium to generate electricity through a betavoltaic process, where beta particles released by tritium decay are converted into electricity via a semiconductor. This launch was part of the Transporter-17 mission, a rideshare flight that included payloads from various companies and organizations, demonstrating the feasibility of integrating nuclear satellites into standard commercial missions.

The BOHR satellite weighs approximately 10 kg and measures 30x20x10 cm. According to City Labs, the CubeSat design has undergone rigorous safety testing to ensure that tritium is not released in the event of a launch failure. Tritium, an isotope of hydrogen, emits low-energy beta particles that are easily contained by a thin layer of material, significantly reducing the risks of radioactive contamination compared to other isotopes like plutonium.

Why Is This Important?

Historically, nuclear power in space has been the exclusive domain of government agencies such as NASA and ESA. NASA has used radioisotope thermoelectric generators (RTGs) with plutonium-238 in iconic missions like the Voyagers (launched in 1977 and still operational), the Cassini and New Horizons probes, and the Curiosity and Perseverance rovers on Mars. These RTGs convert heat from radioactive decay into electricity but require plutonium-238, a scarce and highly regulated material due to its radioactivity and potential weapons use. The launch of BOHR marks a paradigm shift: it demonstrates that private companies can safely and commercially develop and launch nuclear satellites. Tritium also emits far less radiation than plutonium, simplifying pre-launch logistics and safety. City Labs, founded in 2009, has spent over a decade developing betavoltaic batteries for terrestrial and space applications, and this milestone validates its technology in the orbital environment.

The use of tritium is not new in space applications; NASA has used small amounts in experiments, but never in a commercial satellite. Tritium's key advantage is its 12.3-year half-life, providing a continuous power source for over a decade, ideal for long-duration missions where solar panels are ineffective (e.g., on the dark side of the Moon, on asteroids, or in deep space). Additionally, the betavoltaic process produces no significant waste heat, simplifying satellite thermal design.

Consequences and Impact

This milestone paves the way for long-duration space missions, such as interstellar probes or lunar bases, that require reliable and long-lasting power sources. For the commercial space industry, it represents a new business opportunity: nuclear satellites can provide continuous power in environments where solar panels are ineffective (like the dark side of the Moon or deep space). It also reduces reliance on batteries and solar panels, which have limited lifespans and efficiency. Companies like Astrobotic, Blue Origin, and others are developing lunar landers that could benefit from this technology to maintain operations during the lunar night, which lasts 14 Earth days.

The impact on the small satellite market is significant. According to a 2024 Euroconsult report, the CubeSat market is expected to grow from $2.1 billion in 2023 to $4.6 billion by 2030, driven by communications, Earth observation, and defense applications. The availability of compact nuclear power sources could open new segments, such as long-duration low Earth orbit (LEO) missions requiring constant power for high-consumption payloads, or communications satellites in geostationary orbits where solar panels are large and heavy.

Additionally, the launch of BOHR could accelerate regulation of commercial nuclear satellites. Currently, regulations from the FAA and the White House Office of Space Policy require rigorous safety assessments for any nuclear payload. City Labs has worked with NASA and the Department of Energy to ensure compliance, setting a precedent for future launches.

What Readers Should Know

The use of tritium is a key advantage: its low radioactivity minimizes contamination risks in the event of a launch failure. Still, any nuclear satellite must comply with strict safety regulations. The Transporter-17 mission, being a rideshare launch, demonstrates that these satellites can be integrated into standard commercial missions. This is just the beginning; more companies are expected to follow City Labs' lead. In fact, U.S. company NanoAvionics has already announced plans to incorporate betavoltaic batteries into its satellite platforms, and the European Space Agency (ESA) is evaluating tritium for asteroid exploration missions.

However, challenges remain. The power generated by betavoltaic batteries is relatively low (on the order of milliwatts to watts), making them suitable for low-power loads or maintaining critical systems during periods of darkness. For high-power missions, such as electric propulsion or high-bandwidth communications, larger RTGs or nuclear fission reactors will be needed, which are still under development by NASA and the U.S. Department of Defense (project DRACO).

In summary, the launch of BOHR is a historic milestone marking the beginning of the commercial nuclear power era in space. While tritium offers safety advantages, betavoltaic technology still has power limitations. Nevertheless, it opens the door to a new generation of more autonomous and durable satellites, and could be a key step toward human exploration of the solar system.