Detectability of Coastal Landforms on Titan With the Cassini RADAR

Abstract

Earth's coastlines serve as the intersection for numerous physical and chemical processes between terrestrial and marine systems. Liquids of different compositions meet, materials eroded from the continents are concentrated in sedimentary deposits, and the diverse planform morphologies of coastal landforms are shaped by erosional and sediment transport processes. Accordingly, coastal landscapes preserve valuable records of processes that govern Earth's climate, materials, and tectonic history. Applying our understanding from Earth to the coastlines around Titan's liquid hydrocarbon seas allows us to investigate the climate history of the only other known active hydrological system. The study of Titan's coastlines, particularly its deltas, however, remains challenging due to the limitations of Cassini Synthetic Aperture Radar (SAR) data and the transparency of Titan's fluids to microwave radiation. To understand these limitations, we developed a numerical model to simulate Earth's coastlines as they would appear in Cassini SAR images. We show that multi-kilometer-scale landforms are detectable on Titan, provided there is sufficient contrast between the land surface and seafloor. We revisit Titan and show that many of its large coastal rivers do not terminate in deltas, in contrast to Earth. Additionally, we uncover submerged features on Titan's seafloors, suggesting sea-level cycling and/or active sub-aqueous flow. We propose preliminary hypotheses to explain the presence or absence of various coastal landforms on Titan, offering directions for future investigations into Titan's climate and materials. Moreover, we emphasize the opportunities and benefits a superior imaging system at Titan could provide to both Titan science and studies of Earth's changing coasts.