Planetary surfaces

Decoding Titan landscapes with help from Earth and Mars

In exploring Saturn’s moon Titan, the Cassini mission revealed a surface with striking resemblances to Earth, including features formed by ponded and flowing liquid. The materials for landscapes on Titan – likely liquid hydrocarbons eroding and transporting material from an icy substrate – are markedly different from those on Earth. Yet familiar fluvial features occur at a range of scales, from rounded cobbles to drainage networks that can span hundreds of kilometers and empty into seas. An important caveat is that these inferences come largely from radar images that incompletely resolve the surface. Therefore, current data leave ambiguity about the processes that shape Titan’s surface, limiting our ability to reconstruct past landscape evolution and the modern hydroclimate. Together with collaborator Dr. Alexander Hayes and his team at Cornell University, we are actively developing a new framework to tackle these ambiguities using a comparative planetary approach, leveraging the landscapes of Earth and Mars. This work is funded by the NASA Solar System Workings Program.

Interpreting the sedimentary record of Mars climate

A comparison of low-latitude sedimentary deposits on Mars with the Selenga Delta, Russia (DiBiase et al., 2013)

The landscapes and sedimentary deposits of Mars hold a key record planetary climate. Ancient fluvial deposits at low latitudes record periods of surface water flow, while ice-rich deposits at mid- and high latitudes record more recent climate evolution through high-amplitude changes Mars’ orbit. Our group has used high-resolution satellite images and digital elevation models to identify and quantify stratigraphic relationships in these diverse settings in order to interpret Martian climate history. This work has yielded the identification of a repeating, meter-scale sequence in distantly separated outcrops of the north polar layered deposits, which suggests a quasi-periodic deposition process; and sedimentary evidence that a standing body of water once occupied the northern lowlands of Mars. In ongoing work funded by the Virginia Space Grant Consortium, we are developing new numerical models to test hypotheses for the development of the largest sedimentary fan on Mars, at the outlet of Hypanis Valles.