The mysteries of the Occator crater on Ceres have continued to puzzle astronomers and the public, even as we have seen increasing resolution in recent photos. The latest photos show a resolution of 140 meters per pixel and reveal striking details, though the jury is still out on what exactly the bright material is and where it came from.
It seems incredibly likely that the bright spots are ices of some sort, maybe even water ice, since Ceres is a water-rich body, and may have more water than Earth! One hypothesis is that Ceres has a subsurface layer of water, almost like a global ocean, and the collision that formed the Occator crater broke through to this layer, forcing water upward to create the icy region we see.
More data is coming in, as the Dawn spacecraft is working through its science operations around Ceres with low altitude mapping runs. Each image the spacecraft takes of the crater helps us create a 3D map of the surface feature, since each picture taken is from a slightly different angle as the spacecraft moves in its orbit. The video below shows the map in a beautiful rendering, from the Dawn team.
The most interesting part of the footage for me is seeing the false colour map showing the elevation of layers. notice that all of the bright icy spots are located in the deepest part of the crater, a supporting argument for the upwelling and eventual freezing of water from below the crust.
As the data comes in, we will see exactly what the ice is made of. Dawn has a Neutron and Gamma Ray detector, which can characterize the elemental composition of the dwarf planet. It also has a visible and infrared mapping spectrometer, which tells uis what minerals are present on the surface. Combined with the visual data, we can characterize what the surface composition of this alien world really is.