Ceres is a dwarf planet and the largest object in the asteroid belt between Mars and Jupiter. NASA's Dawn mission is studying the remote world, and the Dawn team have two new findings relating to a global ocean that might have at one time covered the surface of Ceres. One of the studies indicates that the crust of Ceres is made up of ice, salts and hydrated materials that are the leftovers of an ancient ocean, and another related study indicates that under the hard crust is a softer, deformable layer that is a signature of residual liquid left over from an ocean.
Julie Castillo-Rogez, co-author of both the studies says, "More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground."
Highly precise measurements of changes in the orbit of the spacecraft has indicated that there are gravitational anomalies on Ceres, which can be correlated with surface features such as craters and a lonely mountain on Ceres known as Ahuna Mons. The findings suggest that Ceres was geologically active at one point of time, if not at the present. The finding indicates a variable density of the crust of Ceres which was light like ice, but strong and hard at the same time. This seemingly contradictory finding led the researchers to model the changes to the surface of Ceres over time.
The models of the change in the surface over time indicates that there are reservoirs of water, remnants of the ancient global surface ocean, deep within the interiors of Ceres. The researchers believe that the surface of Ceres once had more pronounced features, that have eroded or flattened out over a period of time. Such a transformation requires the outer crust to be very hard, as well as a softer layer beneath the surface. The study indicates that the global surface ocean on Ceres existing more than four billion years ago.
Landing a craft on Ceres can potentially contaminate the dwarf planet, so scientists find it better to observe the world from a distance. Ceres has a number of mysterious features, including almost perfectly pyramidal mountains and unusually bright spots in the craters, all of which can be seen on Google Maps.