When
Where
Dr. Steven Desch, Associate Professor at Arizona State University, is the scheduled speaker.
The Despite their small sizes, low temperatures, and their general remove from other bodies, Kuiper Belt objects (KBOs) nonetheless surely experience such geological processes as small impacts that alter their surfaces, large impacts that strip their surfaces, differentiation, and also possibly cryovolcanism, in which liquid water acts as lava. Because water ice is amorphized by cosmic rays on short timescales, the presence of crystalline water ice on the surfaces of KBOs and icy satellites, inferred from reflectance spectra, indicates a renewed surface. Cryovolcanism has been suggested as the renewing agent, but I will show that ice on outer planet satellites is rapidly annealed due to localized heating by micrometeorite impacts, and KBO surfaces may be similarly annealed if dust fluxes are about 100 times greater than at 18 AU.
Despite the lack of compelling spectral evidence for it, cryovolcanism may nonetheless be common on KBOs. I will present thermal evolution models of KBOs that show that the presence of a few percent ammonia in the ice will enable partial differentiation of KBOs and effective trapping of radiogenic heat. Even KBOs as small as Charon (radius 600 km) may retain subsurface liquid today, and I discuss mechanisms by which this liquid could be brought to the surface. Finally, I discuss the likely state of the surface of the KBO Haumea when it was struck by another KBO and its surface was stripped. I discuss implications for the numbers and spectral characteristics of the objects in Haumea's collisional family.