In July of 2015 the New Horizons spacecraft flew through the Pluto system, initiating detailed exploration of the Kuiper belt. Pluto turned out to be a world of remarkable geologic diversity, and its surfaces display a range of ages, suggesting geologic activity of various forms has persisted for much of Pluto’s history. Pluto has some familiar features (e.g., tectonics, cratering) but also features that are unique (e.g., a giant convecting nitrogen ice sheet, and large cryovolcanic constructs). Pluto also has a thin atmosphere that creates seasonal cycles of volatile ice (N2, CH4, and CO) sublimation and redeposition that reshape and mantle Pluto’s surface.
I will give an overview of Pluto and the New Horizons mission, and then focus on my recent work to understand a very large area of cryovolcanic resurfacing on Pluto. This region is dominated by enormous broad rises with hummocky flanks (tens of km across and a few to ~7 km high). Similar features do not exist anywhere else in the imaged solar system. Through analysis and modelling of the geomorphology and composition of the region, we conclude creation of this terrain required multiple eruption sites and a large volume of material (>10^4 km^3) to form what we propose are multiple domes, some of which merge to form more complex planforms. The existence of these massive features suggests Pluto’s interior structure and evolution allows for either enhanced retention of heat or more heat overall than was anticipated before New Horizons, which permitted mobilization of water-ice-rich materials late in Pluto’s history.