If you were riding aboard NASA’s Dawn spacecraft as it orbits dwarf planet Ceres, you would see something like the softly cratered world in the video above. Released today, the animation used 80 images from Dawn to construct a 3-D representation of Ceres, the largest body in the asteroid belt. A background starfield has been added and vertical relief is exaggerated by a factor of two. In other words, the flat-bottomed craters on Ceres’ surface are even smoother than they appear here — a characteristic that could be caused by a layer of buried water ice, perhaps the frozen remnant of a former underground ocean.
“The Dawn team is investigating what the landforms imply about the presence and nature of any water reservoirs in Ceres,” says UCLA’s Christopher Russell, principal investigator for the Dawn mission.
And then there are those enigmatic bright spots pockmarking the surface. Scientists still aren’t sure what the bright spots are, but speculation is centered on the spots being highly reflective ice. Just how that ice ends up on the surface is not yet clear.
“I can’t take my eyes off those bright spots. They really make Ceres special and add to the mystery at this point rather than settle any debate,” Russell says. (You can vote for your own favorite explanation here.)
Since early March, ion-propelled Dawn has been orbiting Ceres and gently spiraling to lower altitudes. The images used to produce this animation were shot from 13,600 and 5,100 kilometers away. Now, Dawn is hovering just 4,400 kilometers above Ceres, getting ready to take an even closer look at a world that is warmer and more watery than any of its neighbors.
Before arriving at Ceres, Dawn visited Vesta — a large, dense body that is the second-most massive in the asteroid belt. Unlike Ceres, Vesta has a heavily scarred surface. Enormous impact basins are gouged into its south pole, and its equator is marked with deep troughs comparable in size to the Grand Canyon. Ultimately, comparing these two giants among space rocks will help scientists learn more about the early ages of the solar system, as well as the histories of the two bodies themselves.
For now, “I cannot help but contrast the Ceres surface with that of Vesta,” Russell says. “While both are pockmarked with craters, there seems to be much more land motion on Ceres — flows, landslides, collapses of structures, relaxation of structures.”