NASA scientists have looked at some special features on the surface of Ceres which they believe formed due to material moving within the dwarf planet.
Based on detailed observations from NASA’s Dawn spacecraft, researchers have discovered a new class of fractures, which they called pit chains and crater chains. The team identified over 2,000 cracks greater than 1 kilometer (0.6 miles) in length around craters on Ceres' surface. But as reported in Geophysical Research Letters, they believe that pit chains have a different origin.
Several explanations have been put forward to explain them but the team considers only one to be likely. Based on their location, researchers first suggested that craters and pit chains had a common origin. When an asteroid hit the dwarf planet, the surface around it cracked under the stress. But crater chains differ significantly from pit chains since pit chains are more irregular and lack raised rims. This striking diversity in morphology makes this explanation unconvincing.
Another explanation is related to the global ocean that, according to researchers, might have covered the dwarf planet, once upon a time. Could the ocean freezing form such structures on the surface? The team doesn’t believe so as the fractures aren't evenly distributed around Ceres.
The researchers instead point the finger at internal dynamics. They think motions of less dense material form the best explanation. These would create an upwelling in the deeper layer of the planet, which would make the corresponding region on the surface primed for the formation of pit chains.
"As this material moved upward from underneath Ceres' surface, portions of Ceres' outer layer were pulled apart, forming the fractures," lead author Dr Jennifer Scully, an associate of the Dawn science team at NASA's Jet Propulsion Laboratory, said in a statement.
The team hopes that these observations will be incorporated into new models explaining how the dwarf planet has evolved since the formation of the Solar System. Ceres is the largest object in the Asteroid Belt and the only dwarf planet in the inner solar system. It is orbited by NASA’s Dawn whose mission has just been extended into late 2018.