Radioactive heat in Ceres drove the dwarf planet’s fractured geology
Radioactive matter within the dwarf planet Ceres may help drive geological activity there. With a diameter of about 940 kilometres (585 miles), Ceres is by far the largest member of the asteroid belt. In 2015 NASA’s Dawn spacecraft became the first orbiter around Ceres. The probe revealed the dwarf planet was covered in features resembling those from tectonic activity, such as a continent-like plateau and criss-crossing fractures. Now research suggests heat from the decay of radioactive elements within Ceres might help keep it geologically active.
Scientists analysed the interior of Ceres using computer models previously applied to bigger planets. Results suggested that because Ceres is relatively small, it lacked a gravitational pull strong enough to result in powerful collisions to heat it up. As such, Ceres may have started off cold. Over time, the decay of radioactive elements such as uranium and thorium within Ceres may have heated up the dwarf planet until its interior became unstable. “What I would see in the model is, all of a sudden, one part of the interior would start heating up and would be moving upwards and then the other part would be moving downwards,” study lead author Scott King, a geoscientist at Virginia Tech, said.
Such instability might explain some of the surface features the Dawn mission saw on Ceres. For example, its large plateau formed on just one side of the dwarf planet, with nothing similar on the other side, and its crisscrossing fractures were clustered around the plateau in a single location.
The concentration of these features in one hemisphere suggested instability concentrated on just one side of the asteroid. “It turned out that you could show in the model that where one hemisphere had this instability that was rising up, it would cause extension at the surface, and it was consistent with these patterns of fractures,” King said. These findings suggest Ceres did not follow a planet’s typical pattern of hot first and cool second, but a pattern of cool, hot and then cool again.