Giant crater on Ceres with bright spots may be the most fascinating place in the Solar System
For a few months in 2018, as NASA’s Dawn spacecraft used up its last drops of fuel, it gave scientists an incredibly detailed look at one of the strangest places in the Solar System: Occator crater. That’s the name of a massive impact site on the dwarf planet Ceres, tucked away in the asteroid belt. In the mission’s last months, Dawn flew just 35 kilometres (22 miles) above the dwarf planet’s surface and focused its energies on Occator crater. The data collected from Dawn suggests that cryovolcanism may have begun just 9 million years ago on Ceres, continuing for several million years. A series of bright deposits formed over that time from brine seeping out from Ceres’ mantle through the upper layer of rock, with activity recorded as recently as a million years ago.
Another finding is a specific form of salt found so far only on Earth – and now on Ceres – that is particularly short-lived, on the scale of centuries. The combination suggests that the brines that deposited them on the surface must have done so very recently. These salts could also solve the puzzle of what’s keeping Ceres relatively warm without gravitational tugging, and could be responsible for maintaining pockets of liquid within the dwarf planet.