Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past.
Mohamed Ramy El-MaarryOlivier GroussinNicolas ThomasMaurizio PajolaA-T AugerB DavidssonX HuStubbe HviidJ KnollenbergC GüttlerCecilia TubianaSonia FornasierC FellerP HasselmannJean-Baptiste VincentH SierksC BarbieriP LamyR RodrigoD KoschnyH U KellerH RickmanMichael F A'HearnM Antonietta BarucciJ-L BertauxIvano BertiniS BesseDennis BodewitsGabriele CremoneseV Da DeppoS DebeiM De CeccoJ DellerJ D Prasanna DeshapriyaMarco FulleP J GutierrezM HofmannW-H IpL JordaGabor KovacsJ-R KrammEkkehard KührtMichael KüppersLuisa M LaraM LazzarinZ-Yi LinJose Juan Lopez-MorenoSimone MarchiF MarzariStefano MottolaGiampiero NalettoN OklayA PommerolFrank PreuskerF ScholtenXian ShiPublished in: Science (New York, N.Y.) (2017)
The Rosetta spacecraft spent ~2 years orbiting comet 67P/Churyumov-Gerasimenko, most of it at distances that allowed surface characterization and monitoring at submeter scales. From December 2014 to June 2016, numerous localized changes were observed, which we attribute to cometary-specific weathering, erosion, and transient events driven by exposure to sunlight and other processes. While the localized changes suggest compositional or physical heterogeneity, their scale has not resulted in substantial alterations to the comet's landscape. This suggests that most of the major landforms were created early in the comet's current orbital configuration. They may even date from earlier if the comet had a larger volatile inventory, particularly of CO or CO2 ices, or contained amorphous ice, which could have triggered activity at greater distances from the Sun.