City Labs Seeks Approval for Tritium Satellite Heaters
The company aims to launch 10 million curies of tritium to provide lunar landers with heat during the night.
Updated on Oct. 31, 2026 in Nuclear
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City Labs has filed an application with the Federal Aviation Administration to increase its authorized tritium payload to 10 million curies per mission. This technology aims to provide essential heat to lunar landers, which currently face operational risks during the freezing lunar night.
Why it matters
Tritium heaters are designed to sustain lunar landers when solar power is unavailable, offering a mass-efficient alternative to heavy battery-based heating systems. Using these units could prevent the total loss of expensive missions that otherwise fail during the long lunar night.
Each individual heater unit generates approximately 30 milliwatts of heat using 1,000 curies of tritium. These modular units are designed to be placed directly on chips or batteries to provide necessary thermal regulation.
The players
City Labs
City Labs is a private aerospace company that specializes in developing modular nuclear radioisotope heating units for satellite and lunar missions.
Federal Aviation Administration
The Federal Aviation Administration is the national authority responsible for regulating commercial space transportation and payload authorizations in the United States.
The details
City Labs plans to expand upon its July 2026 satellite mission, which successfully utilized 20 curies of tritium. The company is seeking an amendment to its existing license class to scale its thermal output capabilities significantly.
Timeline
2019: National Security Presidential Memorandum 20 regulatory path opened.
July 2026: The BOHR nuclear-powered satellite launched.
October 2026: City Labs published BOHR satellite telemetry data.
December 2026: Expected formal submission of FAA application.
January 2027: Target date for FAA amendment approval.
The Big Picture
The application aligns with National Security Presidential Memorandum 20, which facilitates commercial access to nuclear isotopes in space. This marks a shift from state-run nuclear programs toward a commercialized model for spacecraft thermal management.
Successful adoption of these tritium heaters could lower the mass requirements for lunar landers, leading to more affordable and sustained robotic exploration of the Moon. This technology could ultimately enable longer-term scientific research on the lunar surface by replacing legacy battery-heavy heating designs.
The takeaway
Commercial nuclear isotope usage is moving toward higher payload limits to solve critical thermal management challenges in deep space. Developers must continue to navigate stringent FAA regulatory frameworks to ensure these power sources remain safe for orbital and lunar environments.
What happens next
City Labs expects to submit its formal application to the FAA in December 2026, with an amendment approval target of January 2027.
Further reading
For more information on nuclear space technologies, visit the Nuclear section.
Source note: This article includes information reported by Satnews.
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