Mars may contain a record of its last few millions years of climate change in its polar ice sheets, including the Polar Layered Deposits (PLD). However, what these geologic features tell us about the link to current and past climates is not well understood.
I have used impact craters as a tool for understanding the surface ages of these ice sheets to place a fixed time in their stratigraphic record. My wide variety of projects and collaborations, from understanding interannual changes in powder "avalanche" events and ice lenses within small craters to a new USGS Science Investigation Map of the South Polar Layered Deposits and surroundings, all work towards understanding the recent history of the PLDs and what that means for how these polar ice sheets formed and are behaving in the present day. Future plans include proposing instruments to the next generation of Mars orbiting spacecraft.
For the Moon, I focus on understanding where water ice and other volatiles may be thermally stable on the surface and in the near-subsurface in the present-day. While these deposits could have potential resource value, they could also record traces of either a cometary or volcanic origin. This is key to understanding if rocky planet volatiles come from delivery via icy objects or internally, through volcanism, and hold implications for airless rocky bodies within and outside of our solar system.
I have worked with Diviner lunar radiometer data to understand where volatiles would be present on the lunar surface and subsurface in the present day. This work suggests several Diviner-footprint (~300 m) sized regions where volatiles from volcanic and cometary sources would be predicted to be stable at the surface. These are regions where future exploration could reveal the presence or absence of “tell tale” volatiles from their source processes.
Outside of volatiles directly, I am a co-investigator on the Lunar-VISE mission team. The Grutheisen domes are unique as they may be silicic domes, which is not typically expected from lunar mare volcanic processes. Understanding how these domes formed is key to understanding how late-stage lunar volcanism changed from earlier, volatile-delivering mare volcanism. My role on the project is to achieve science closure between nuclear spectroscopy and thermal observations, working across instruments and measurement techniques to answer the mission’s key science questions.
The discovery of Main Belt Comets and confirmation from the Dawn mission that Ceres is in fact ice-rich has re-emphasized the importance of this question in understanding how water ice could be delivered to the inner solar system. My research to answer this question has been focused on Ceres, and in mission development for exploring the Themis asteroid family.
For Ceres, my work focuses on how near-surface water ice escapes to space, including what conditions could explain the largest asteroid’s periodically detected exosphere. How asteroid-like airless bodies lose volatiles is key to understanding how viable a source of major amounts of water asteroids could be if scattered into the inner solar system.
My data-driven modeling efforts during the mission found that while exposed water ice patches could match telescopic observations of Ceres’ exosphere from the Herschel Space telescope, these water-ice patches would be short-lived as regolith contamination would build up at the surface. Using an impact Monte Carlo model, I was able to demonstrate that small impacts can contribute in a major way to Ceres’ exosphere perhaps more consistently than other transient events, like solar energetic particle bombardment.
As part of the GRaND team during and after the mission, I utilize neutron data from the Dawn mission to explore how complex craters may enhance the near-surface abundance of hydrogen (and therefore water). I have developed numerical models that incorporate ice retreat and salt dehydration to narrow down how Ceres can keep water ice near the surface. I currently co-advise a postdoctoral scholar, whose Ceres project quantifies how volatile escape feeds the persistently shadowed regions. This work complements broader projects in understanding the interior chemistry and evolution of Ceres, a potential relic Ocean World.