ESA Science & Technology - Seasonal exposure of carbon dioxide ice on the nucleus of comet 67P/Churyumov-Gerasimenko

Publication date: 17 November 2016

Authors: Filacchione, G., et al.

Journal: Science
Year: 2016

Copyright: AAAS

Published online 17 November 2016

Carbon dioxide is one of the most abundant species in cometary nuclei, but due to its high volatility CO₂ ice is generally only found beneath the surface. We report the infrared spectroscopic identification of a CO₂ ice-rich surface area, located in the Anhur region of comet 67P/Churyumov-Gerasimenko. Spectral modeling shows that about 0.1% of the 80×60 m area is CO₂ ice. This exposed ice was observed a short time after exiting from local winter; following the increased illumination, the CO₂ ice completely disappeared over about three weeks. We estimate the mass of the sublimated CO₂ ice and the depth of the surface eroded layer. The presence of CO₂ ice is interpreted as the result of the extreme seasonal changes induced by the rotation and orbit of the comet.