One dwarf planet, hold the ice
As research into the dwarf planet Ceres progresses, evidence of the existence of ice on its surface continues to grow. Scientists speculate that one in every 1,000 water molecules that circulates the planet gets caught in cold regions with temperatures that remain consistently below minus 240º F (-151º C). Over a period of billions of years, this could lead to the formation of ice layers that might be detectable today. However, a new study using data from NASA's Dawn spacecraft suggests that despite its presence, ice does not play a major role in the formation of Ceres' surface features.
After entering orbit around Ceres in March 2015, the Dawn spacecraft used its instruments to gather data on the dwarf planet that has led to the creation of digital terrain models and three-dimensional visualizations of its surface. Using these models and visualizations, the team behind the current study was able to analyze specific aspects of Ceres' topography – such as impact craters, linear structures, domical features and lobate flows – and paint a clearer picture of the planet's surface features.
The resulting imagery reveals a planet dominated by craters with sharp walls and floors that dig deep into its surface. In addition, the existence of angular polygonal craters on its surface suggests a fractured crust, a finding that the team says is only possible if Ceres' surface is brittle enough to allow for these fractures, while at the same time possessing enough strength for them to have been retained for extended periods of time.
"Based on our analysis, the crust of Ceres is too strong to be dominated by ice," says Debra Buczkowski of the Johns Hopkins University and lead author of the study. "While surface features such as the lobate flows show that water ice is present in the dwarf planet's upper crust and on the surface in some locations, it appears not to be a major factor in creating surface features."
The new data also suggests a water-rich mantle and a silicate core beneath Ceres' crust, as well as evidence of cryomagmatism – a collective term for the water, ammonia or methane that some planets expel from their cryovolcanoes – pointing to the possibility that the planet was geologically active at some point it in the past.
Although the goal of the new study – to answer the numerous lingering questions about the surface and interior makeup of Ceres – was partially achieved, further examination of its surface features will need to be conducted in order to answer remaining questions, including if and when geological activity took place in the planet's historical timeline.
The findings were published in the journal Science.
Source: Johns Hopkins University