European researchers are developing batteries that use a radioactive isotope to power long missions in the Solar System.

ESA has relied on US or Russian partners, which have used plutonium-238 batteries.

Americium’s big advantage over plutonium is that it is cheaper and more abundant, repurposing waste that would otherwise be useless.

Americium has a longer half-life than plutonium-238, which means it lasts longer but packs less power per gram. But because americium is more readily available, producing one watt of power costs about one-fifth as much as it does using plutonium.

Over the next three years, the European Devices Using Radioisotope Energy (ENDURE) team will develop prototypes into models that can be tested in mission-like conditions.