Martian Deltas: Experiments on the Impact of Sediment Density on Delta Morphology as a Proxy for Gravity

Deltas on Mars are prime targets for robotic exploration in the search for extraterrestrial life. While terrestrial deltas serve as a framework for interpreting Martian deltas, Mars' lower gravity affects sediment transport, potentially altering delta morphology (Braat et al., 2024). To explore this, we conducted physical experiments to investigate the impact of gravity on autonomous delta formation. By studying differences in delta evolution and morphodynamics between Earth and Mars, we can learn how to better apply our terrestrial knowledge to the Martian landscape.

Physical experiments were conducted in the Earth Simulation Laboratory at Utrecht University in a facility called the Metronome. Water (300 L/h) and sediment (2 L/h) were supplied to a 3 cm-deep flume, where we simulated Martian gravity by reducing sediment density (using nutshell grains, ~1350 kg/m³) without altering grain size. Comparisons are made to deltas with quartz particles (~2650 kg/m³) under otherwise identical conditions, isolating sediment density as a proxy for gravity.

Preliminary results indicate that reduced sediment density produces deltas with gentler slopes, larger surface areas for equal deltas volumes, more irregular coastlines, and different channel dynamics. Simulated Martian channels on the delta appear wider and shallower than their Earth counterparts under equal conditions and stay in place longer. While the data acquisition is being finalized, data analysis is still ongoing. Nonetheless, these findings show great promise to provide insights into how gravity influences delta morphology and improve our ability to apply our knowledge of deltas on Earth to ancient Martian environments.