‘Abundant’ Water Ice Found in Asteroid Belt

Ceres’ Haulani Crater, with a diameter of 21 miles (34 kilometers), shows evidence of landslides from its crater rim as seen by NASA’s Dawn spacecraft. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

(CN) – A rocky dwarf planet with mysterious bright spots could have water ice hidden in shadowy crater floors, according to NASA studies that also analyzed images of dark pockets that might conceal ice volcanoes.

The findings, presented Thursday at a meeting of the American Geophysical Union, come after cameras on NASA’s Dawn spacecraft revealed flowing material on the floors of several craters on Ceres, a dwarf planet in the asteroid belt between Mars and Jupiter.

“The members of the (Dawn science) team expected a lot of things, but not what we finally got,” said Ralf Jaumann of the German Aerospace Center. “I was completely surprised, and ‘completely’ means ‘completely’.”

The material erupts from weak spots along the dwarf planet’s surface caused by collisions with large space rocks or other objects. Jaumann and his colleagues believe that the flowing material is a mixture of mud, ice and salts.

While ice volcanoes are not yet confirmed, the observations show that Ceres has water ice in the permanent shadow of crater bottoms that can reach several hundred degrees Fahrenheit below zero.

“These studies support the idea that ice separated from rock early in Ceres’ history, forming an ice-rich crustal layer, and that ice has remained near the surface over the history of the solar system,” said Carol Raymond, deputy principal investigator of the Dawn mission.

Water ice on Ceres is the latest example of nearby – in space terms – planetary bodies that might have once supported life.

“By finding bodies that were water-rich in the distant past, we can discover clues as to where life may have existed in the early solar system,” Raymond said.

Researchers used Dawn’s gamma ray and neutron detector (GRaND) to determine the concentrations of hydrogen, potassium and iron up to a yard below the surface of Ceres. GRaND measures the number and energy of gamma rays and neutrons emanating from the dwarf planet. The limited release of neutrons suggested that the ice contains hydrogen.

“These results confirm predictions made nearly three decades ago that ice can survive for billions of years just beneath the surface of Ceres,” said Thomas Prettyman, GRaND’s principal investigator. “The evidence strengthens the case for the presence of near-surface water ice on the main belt asteroids.”