The arrival of NASA’s Dawn spacecraft at Ceres in 2015 allowed scientists to gain a better understanding of the space rock.
Ceres was previously thought to be a relatively boring dwarf planet that was covered in ice. However the latest findings suggest that the situation is more complex, and certainly more interesting, writes Eva Botkin-Kowacki for The Christian Science Monitor.
NASA spacecraft sends back valuable data
The prevailing opinion was that Ceres had a rocky core surrounded by a layer of ice, with a rocky surface on top. However Dawn has sent back new data which has led scientists to revise their opinion.
According to a new study published Wednesday in Nature Geoscience, Ceres is not as icy as thought. It now appears that the subsurface is made up of rock, ice, salts and other materials.
Another study suggests that the bright spots on the surface of Ceres are highly reflective due to the presence of a number of different salts. The spots were previously thought to have been caused by the impact of the Occator space rock, but data suggests that the salts were not deposited during the impact. It now appears that water-related processes were responsible.
Study of craters changes opinions of Ceres
Impact craters pockmark the surface of Ceres. However they are far deeper than would be expected if the subsurface were made primarily of ice, which would mean that the surface moves and makes the craters shallower.
It was also thought that the craters at the equator would be shallower than at the poles. This is because warmer temperatures would mean that the ice moves more at the equator and fills in the craters, however this is not the case.
“We suggest that you must not have more than about 30 or 40 percent water-ice by volume in Ceres’s interior, because if you had more than that, then the ice would be able to flow too easily and it would erase the topography,” said Michael Bland, lead author of the Nature Geosciences paper and a research scientist at the USGS Astrogeology Science Center and Washington University in St. Louis.
Further research needed into dwarf planet
However there must be other materials present because otherwise composition models would be too dense to match Ceres. “There may be a large inventory of salts on Ceres’ surface,” Julie Castillo-Rogez, a co-author on both papers and a planetary scientist at the California Institute of Technology and NASA’s Jet Propulsion Laboratory working on the Dawn mission. “And all together they could contribute to strengthening the shell.”
Further analysis was undertaken to get a better idea of what these salts might be. Scientists looked at the bright spots in the Occator crater and found large amounts of sodium carbonate.
“The huge amount of carbonates indicates that liquid water was present at Ceres subsurface … some time in the recent past,” said Maria Cristina De Sanctis, lead author of the Nature paper and a researcher at the Institute for Space Astrophysics and Planetology at the National Institute for Astrophysics in Rome.
Scientists believe that there may still be some liquid water present on Ceres, and both papers are pieces of the same puzzle. However it seems likely that it is a highly complicated puzzle with many missing pieces.
Some researchers believe that Ceres formed in the asteroid belt before being knocked out of orbit by a comet and settling in its current position. If that is the case, the dwarf planet could offer great insight into planetary formation.