Dwarf planets

The United States has begun manufacturing nuclear spacecraft fuel for the first time in a generation, but full production of the stuff likely won't begin until 2023 at the earliest.

NASA had been splitting costs with the U.S. Deparment of Energy.

NASA is facing a plutonium shortage that may thwart future missions.

The Department of Energy has made its first plutonium-238 in a quarter century.

A rare type of plutonium has been found in the crust below the deep sea, offering new clues as to how heavy metals form in star explosions and mergers.

Strange hexagonal diamonds may have been jettisoned into space when a dwarf planet collided with a large asteroid around 4.5 billion years ago.

A new model exploring the dwarf planet Ceres suggests radioactivity deep in the small world may have created criss-crossed geology at its surface.