Over the next fifteen years, multiple space agencies and their commercial partners intend to mount crewed missions to the Moon and Mars. In addition to placing “footprints and flags” on these celestial bodies, there are plans to establish the infrastructure to allow for a long-term human presence. To meet these mission requirements and ensure astronaut safety, several technologies are currently being researched and developed.

At their core, these technologies are all about achieving self-sufficiency in terms of resources, materials, and energy. To ensure that these missions have all the energy they need to conduct operations, NASA is developing a Fission Surface Power (FSP) system that will provide a safe, efficient, and reliable electricity supply. In conjunction with solar cells, batteries, and fuel cells, this technology will allow for long-term missions to the Moon and Mars in the near future.

For NASA, having fission reactors for lunar surface operations is a vital part of the Artemis Program, which aims to create a program of “sustained lunar exploration.” This means infrastructure is required, like the Lunar Gateway (where spacecraft will dock and resupply) and the Artemis Base Camp on the surface, where astronauts will eat, exercise, and sleep when not conducting extravehicular activities (EVAs) – i.e., surface operations.

Artist’s impression of the Kilopower fission reactor on the Moon. Credit: NASA/JPL-Caltech

This base will require a considerable amount of electricity so astronauts can recharge rovers, conduct experiments, and produce water, propellant, building materials, and oxygen gas using the Moon’s natural resources – a process known as In-Situ Resource Utilization (ISRU). Jim Reuter is the associate administrator for NASA’s Space Technology Mission Directorate (STMD), which funds the fission surface power project.

“Plentiful energy will be key to future space exploration,” he said in a NASA press release. “I expect fission surface power systems to greatly benefit our plans for power architectures for the Moon and Mars and even drive innovation for uses here on Earth.” The concept builds on NASA’s Kilopower project, an effort to create a small, lightweight fission system that could provide up to 10 kilowatts (kW) of power continuously for at least ten years.

The project wrapped up in March 2018 with the successful completion of the Kilopower Reactor Using Stirling Tech (KRUSTY) demonstrator. This prototype consisted of a solid, cast uranium-235 reactor core (about the size of a paper towel roll) and passive sodium heat pipes that transferred the heat generated by slow fission reactions to high-efficiency Stirling engines, which convert the heat to electricity. 

Based on this success, NASA has since partnered with the U.S. Department of Energy (DoE) – through the Idaho National Laboratory (INL) operated by Battelle Energy Alliance – to develop the Kilopower-inspired FSP for the Artemis Program. This will culminate with a technology demonstration, tentatively scheduled for the early 2030s, which will see a prototype reactor will be sent to the Moon to test its capabilities under lunar conditions.

Artist’s concept of a fission surface power system on Mars. Credit: NASA

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