Dawn Mission: Identifies Areas On Dwarf Planet, Ceres, Accumulate Ice Deposits

The scientists together with NASA's Dawn mission recognized permanently shadowed areas on the dwarf planet Ceres, indicating the ice deposits could exist there now. According to the researchers, most of these areas would likely have been cold enough to trap water ice for billion years.

The study was printed in Geophysical Research Letters, a journal of the American Geophysical Union this week. It was led by Norbert Schorghofer, a Dawn guest investigator at the University of Hawaii at Manoa, Erwan Mazarico, Thomas Platz, Frank Preusker, Stefan E. Schröder, Carol A. Raymond and Christopher T. Russell.

Schorghofer explained that the conditions on Ceres are right for collecting deposits of water ice. He further explained that Ceres has just enough mass to keep water molecules and the permanently shadowed regions we identified are extremely cold--colder than most that exist on the moon or Mercury.

The permanently shadowed areas are located on the crater floor and they do not receive direct sunlight. Although, the areas still receive indirect sunlight. On the other hand, if the temperature settles below about minus 240 degrees Fahrenheit (minus 151 degrees Celsius); the area is a cold trap, which is a good place for water ice to accumulate and remain stable. The cold trap is not yet identified on Ceres, according to the American Geophysical Union.

The researchers examined Cere's northern hemisphere. From Dawn's cameras, they perceived the dwarf's planet craters, plains and other features in three dimensions. They found dozens of sizeable permanently shadowed areas across the northern hemisphere. They spotted the largest one inside the 10-mile-wide (16-kilometer0 crater located less than 40 miles from the North Pole. The permanently shadowed areas occupy about 695 square miles (1,800 square kilometers). The team discovered that about 1 out of every 1,000 water molecules produced on the surface of Ceres will end up in a cold trap during a year on Ceres (1,682 days). That's enough to produce thin but detectable ice deposits over 100,000 years or so.

Chris Russell, principal investigator of the Dawn mission, based at the University of California, Los Angeles stated that some observations suggest Ceres may be a volatile-rich world that is not dependent on current-day external sources.

Ceres is the biggest of the minor planets within the orbit of Neptune and the largest object in the asteroid belt that lies between the orbits of Jupiter and Mars. It is about 945 kilometers in diameter. It is composed of rock and ice. It is estimated to comprise approximately one-third of the mass of the entire asteroid belt.