The world’s first commercial satellite with a nuclear power source has entered orbit. The small spacecraft carries a battery that converts the energy from tritium decay directly into electricity. This technology is designed to operate in conditions of permanent shadow, where solar panels do not work.
Energy from Beta Particles
The Florida-based company City Labs has developed the NanoTritium micro-power source based on betavoltaic technology. Tritium, a radioactive isotope of hydrogen, emits beta particles as it decays, and a semiconductor converts them into electric current. In principle, this resembles a solar panel, except that instead of photons, it uses electrons.
Tritium has a half-life of 12.3 years, so the power output of this source gradually decreases, but even after two decades it continues to generate current. Radioisotope thermoelectric generators, or RTGs, such as those used on the Voyager probes, obtain heat from plutonium-238 and convert it into electricity. The new technology does not require an intermediate heating stage and produces electricity directly.
Testing in Flight
A Falcon 9 rocket launched on July 7 from Vandenberg Space Force Base in California carrying 81 payloads. Among them was the BOHR satellite, or Betavoltaic Orbital High-Reliability, developed by City Labs.
Falcon 9 launch with the Transporter-17 mission and first-stage landing. Video: SpaceX / SciNews.
At this stage, the tritium core is not the spacecraft’s main power source, and BOHR uses solar panels for current operations. The purpose of the launch is to test the performance of the betavoltaic battery in orbital conditions, Space.com reports.
An Alternative for the Lunar Night
Permanently shadowed craters at the Moon’s poles are unsuitable for long-term operation of spacecraft powered by solar panels. Temperatures in such areas drop below −170°C.
Landing missions under the Artemis program are aimed at the lunar south pole region, where deposits of water ice are concentrated near shadowed craters. Studying them requires power sources that do not depend on sunlight.
NASA is already funding the development of nuclear reactors to support a lunar base. Although NanoTritium currently generates too little power for such tasks, City Labs expects to gradually increase its output.
A Regulatory Precedent
The development of BOHR and City Labs’ tritium technologies was funded by the U.S. Department of Defense. The spacecraft also became the first with a nuclear component to be approved by the Federal Aviation Administration under the procedure established by the 2019 National Security Presidential Memorandum NSPM-20.
The company believes that, after successful testing, similar power sources will become available for both defense and private space programs. The low radiation level of tritium has already allowed NanoTritium batteries to be integrated into a standard commercial launch environment without additional safety measures.
