Titan

The Cassini-Huygens mission revealed that the largest moon of Saturn, Titan, is incredibly similar to our own planet. Much like Earth, nitrogen dominates the atmospheric composition, followed by methane and other trace species. Methane participates in the equivalent of Earth’s hydrological cycle, raining down onto the surface, pooling in lakes and seas, and evaporating back into the atmosphere. A vast desert of organic sands wraps around Titan’s equator where winds organize the sand into longitudinal dunes much like the Namib Sand Sea. Channels emerging from mountainous terrain suggest fluvial creation and movement of sediment, perhaps like the cobbles observed in the only image taken at the surface.

Evaporites

Under certain conditions, lakes can deposit relatively pure sediments when they evaporate (think the Bonneville Salt Flats in Utah or Salar de Uyuni in Bolivia). Identifying these evaporites on the surface of Titan can tell us where liquids have been in the past.

The space between the dunes

The sand that makes up Titan’s sand dunes is likely a mixture of organics. Though most spectral images of the surface have too coarse of spatial sampling to resolve dunes and interdunes, one sequences of images revealed an impressive heterogeneity in the areas between the dunes, the interdunes. Within tens of kilometers, the interdune areas exhibit distinctly different spectral signatures, indicating a difference in composition and/or grain size.

Radiative transfer in the atmosphere

The very atmosphere that makes Titan’s geology so unique complicates direct imaging of the surface in the visible and near infrared. Radiative transfer modeling can help disambiguate these atmospheric influences on surface signal. Specifically, I’m interested in understanding the additive (photons that scatter in the atmosphere towards the detector) and blurring (photons scattered off the surface and forward scattered towards the detector) processes at work both to better interpret Cassini data and to facilitate best imaging practices in the next missions to Titan. These scattering processes are particularly important at Titan, but also other worlds with hazy atmospheres like Pluto, our own Earth, and perhaps even exoplanets. For more on our radiative transfer model for Titan, see Barnes et al. 2018.

Astrobiology

Titan’s sediments are likely ultimately sourced from the plethora of organic chemistry at work in the atmosphere. Eventually, atmospheric products find their way to the surface where they are further processed by geological and perhaps further chemical reactions. When Titan haze analogs are mixed with liquid water, they quickly react to form amino acids. Thus, sampling Titan’s sediments offers a unique opportunity to investigate the limits of prebiotic chemistry.

Enceladus

Enceladus is one of the the best locations to search for life elsewhere in the solar system. We investigated what Flagship-class missions to Enceladus might look like in the 2023-2032 decade as preparation for the National Academies Planetary Science and Astrobiology Decadal Survey. Read more about our favored concepted, Enceladus Orbilander in the associated papers on the science and mission concept.