Additional evidence supports suspected cryovolcanism on Ceres

Studies of the surface of the dwarf planet Ceres show evidence of long-postulated “cryovolcanism” in which volcanoes spew cryomagma—slurries of water, ice, and volatiles—rather than lava. Many icy moons, such as Saturn’s Enceladus and Jupiter’s Europa, have features suggesting cryovolcanism. But the identity of that geological activity hasn’t been confirmed. The new data come from NASA’s Dawn spacecraft, which has been orbiting Ceres since March 2015 as it floats in the asteroid belt between Mars and Jupiter. A set of six papers published in Science last week includes an analysis from a team led by NASA Goddard Space Flight Center scientist Ottaviano Ruesch. The researchers studied an area on Ceres known as Ahuna Mons, which they believe was formed by relatively recent eruptions of materials involving carbonates, water ice, and chlorine salts (DOI: 10.1126/science.aaf4286). In addition, a team led by Debra L. Buczkowski of Johns Hopkins University’s Applied Physics Laboratory found evidence that cryovolcanism has occurred at various locations on Ceres (DOI: 10.1126/science.aaf4332). That Ceres appears to be rich in ice and water jibes with previous data sent back from Dawn and increasingly indicates that Ceres has characteristics of both a comet and an asteroid.