NASA tests new americium-based nuclear power for deep space missions

For many years, NASA has explored deep space using radioisotope power systems. These nuclear power systems generate electricity for spacecraft and scientific instruments by converting the heat released from the natural decay of radioactive materials.

The radioisotope plutonium-238 (plutonium oxide) has been NASA’s go-to heat source fuel. However, interest in using americium-241 has long existed. Now, NASA, in collaboration with the University of Leicester, is turning that interest into reality by putting americium-241 to the test.

The project centers around a free-piston Stirling convertor, which turns radioisotope heat into electricity. Unlike traditional engines that use crankshafts, the Stirling convertor operates with pistons that float freely inside the engine. This design minimizes wear since it doesn’t rely on piston rings or rotating bearings. As a result, the convertor can produce more energy over time, supporting longer, more demanding deep space exploration.

The test setup featured contributions from both collaborators. The University of Leicester supplied the heat source simulators and generator housing, while NASA Glenn’s Stirling Research Lab provided the test station, convertor hardware, and support equipment. The Stirling generator testbed was powered by two electrically heated americium-241 heat source simulators, which were the same size as the real ones.

The test yielded satisfactory results. One key strength of the testbed design, as witnessed from the test, is its ability to sustain electrical power even in the event of a Stirling convertor failure. This breakthrough points to a viable future for the Americium-Radioisotope Stirling generator as a dependable energy source for extended deep space missions.

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