Spacecraft have observed evidence of mass wasting events such as landslides and avalanches on the nucleus of every comet they have visited. Missions to comets 9P/Tempel 1, 19P/Borrelly, 67P/Churyumov-Gerasimenko, 81P/Wild 2, and 103P/Hartley 2 have found that mass wasting contributed to the formation of pits, mesas, and smooth flows; caused scarps to retreat; and triggered dust jet activity and outbursts. This image of the Aswan region of Comet 69P/Chuyrymnov-Gerasimenko shows a crack preceding the cliff’s collapse (the arrow denotes the same location in each image), with mass-wasting debris clearly visible at the base of cliff.
However mass wasting events do more than merely change a comet’s surface topography; they are critical to the long-term evolution of comet nuclei. PSI Research Scientist Jordan Steckloff and Senior Scientist Nalin Samarasinha have determined that mass wasting events such as landslides and avalanches are critical to maintaining sublimative activity on comets, which is the defining process of comets. Further, they note that this process offers a mechanism for reactivating dormant comets, which is critical for understanding why comets seem to remain active for much longer than thought possible. “The sublimative torques of Jupiter Family Comets and mass wasting events on their nuclei” by Steckloff and Samarasinha was in the journal Icarus.
