While the dwarf planet Ceres is typically described as a dark and heavily cratered object whose brightest spots are comprised of reflective salts, new research based on findings from the Dawn mission have found evidence of water ice located at or near the dwarf planet’s surface.
The findings, reported online Thursday in the journal Nature Astronomy, “support the idea that ice separated from rock early in Ceres’ history, forming an ice-rich layer, and that ice has remained near the surface over the history of the solar system,” NASA’s Carol Raymond, deputy principal investigator of the Dawn mission, explained in a statement.
As Space.com explained, water is “not entirely uncommon” on Ceres, with both water vapor and in rare cases, exposed water ice having been previously detected on the dwarf planet. In addition, studies have suggested that Ceres is home to a significant amount of underground water ice.
Now, researchers have analyzed images of craters located in the northern polar region of Ceres and found that at least 634 of them were covered in perpetual shadow, accounting for more than 820 square miles (2,120 square kilometers) of the dwarf planet’s surface, the website reported.
Of these craters, only 10 were found to have so-called “bright spots” that reflected high levels of sunlight, the researchers said. By analyzing the wavelengths of light reflected by these areas, the authors of the study determined that only one of these surfaces contained amounts of water ice.
Unlikely that life could survive in such conditions, scientists say
The analysis, which was led by Thomas Platz from the Max Planck Institute for Solar System Research in Germany, focused on “cold traps” – perpetually dark and extremely cold craters in the northern hemisphere of Ceres – NASA explained. These regions are so icy that only a small amount of the ice they contain will turn into vapor over the span of one billion years.
The crater that was found to contain ice was partially sunlit and confirmed by Dawn’s infrared mapping spectrometer, the US space agency said. Its existence demonstrates that “cold traps” on the dwarf planet can be contain water ice, similar to cold, dark craters on Mercury and the moon. While the ice on those two objects likely came from meteors and other objects crashing into their surfaces, the origins of the ice on Ceres are not yet fully understood.
“It could have come from Ceres’ ice-rich crust, or it could have been delivered from space,” co-author Norbert Schorghofer of the University of Hawaii said in a statement. However, as Platz told Space.com, “It is unlikely that the solar wind formed much of the water on Ceres, since it’s so far away from the sun,” He also called it “surprising” that ice was only found in one crater.
While evidence of water would normally be encouraging in terms of the hunt for life on other planets, Platz noted that the cold conditions on Ceres, which can reach 60 Kelvin (-351 degrees Fahrenheit, -213 degrees Celsius) in the permanently shadowed regions all but eliminated such a possibility. Mining the ice for use in rocket fuel is somewhat more likely, he told Space.com, but even that would require robots running on batteries, not solar power, due to the lack of light.
Image credit: NASA JPL