Americium-241 Is Going to the Moon in Radioisotope Heater Unit Designed to Survive the Lunar Night

Not long ago, autoevolution brought you word of plans to integrate radioactive isotopes into astronauts' suits so that they’d have their own portable heat sources while exploring the Moon, even during the long and freezing lunar nights. The americium-241 isotope that’s at the core of this upcoming space tech will go to the Moon much sooner than that, though, and as part of a completely different system.

Americium-241, a radioactive isotope with a half-life of 432.6 years and potentially deadly if inhaled, swallowed, or otherwise absorbed inside the body, is at the center of space technologies developed by a company called Zeno Power Systems.

As already presented for spacesuit applications, in a form called Extended Astronaut Radioisotope-EVA in Nighttime and Deep-space Icy Landscapes (EARENDIL), it would be crucial to keeping astronauts comfortable for longer periods of time on the Moon by providing continuous, passive warmth.

For that to happen, though, Zeno would first have to test the merits of the idea and determine what it would require for americium-241 on the Moon to be safe. And that’s part of the reason why one of Zeno’s technologies powered by this isotope, the Survive-the-Night Package with a Radioisotope Heater Unit (RHU), will go to the Moon as soon as 2028.

The tech will fly to the Moon’s near side on board a Firefly Aerospace Blue Ghost lander performing a Commercial Lunar Payload Services (CLPS) mission on behalf of NASA. The main goal for its presence up there is to demo nuclear energy capabilities of operating in temperatures that can reach as low as minus 275 degrees Fahrenheit (minus 135 degrees Celsius).

The RHU Zeno is sending up there consists of a five-watt thermal americium-241 unit, complete with structural, communications, electrical power, command and data handling, and thermal management subsystems.

It is capable of generating passive thermal energy through the natural decay of the onboard radioactive material, an internal heat and power source that doesn’t require access to sunlight, for instance. No numbers on its exact capabilities have been released at the time of writing.

After the Blue Ghost lander makes contact with the lunar surface, during the lunar day, it will power the other onboard payloads using its own solar power system. When night descends, and for its entire two-week duration, that task will pass over to the Zeno RHU, allowing the lander’s payloads to continue to operate and send their data back to Earth.

If this novel idea works, it could become another proven path NASA could follow to ensure continuous operations on the lunar surface, something that is more or less crucial to the establishment of the planned Moon Base and the de facto start of humanity’s plans to colonize the suitable worlds in the solar system.