Ground-Breaking Geologic Processes in the Solar System

Abstract:

NASA mission proposals of today must promise “ground-breaking” new results. “Ground-breaking” is a buzzword, but sounds good to a geologist who likes to study active processes. Great progress in understanding active processes on the Moon and Mars has resulted from very-high-resolution (sub-meter scale) repeat imaging (monitoring) by LROC and HiRISE. Such changes include new impact craters and mass wasting on both the Moon and Mars. One martian surprise was not just finding that the gullies or ravines are forming today, but that they are forming in times and places with CO₂ frost on the ground. The geomorphology of these gullies is a perfect match for water-carved gullies on Earth, but the CO₂ buffers the ground and air temperatures to near 150 K, far too cold for liquid water to play a role. Snapshot geomorphology, even at very high resolution, does not enable a unique interpretation of geologic processes. Repeat imaging led to discovery of the martian Recurring Slope Lineae (RSL), which form at the warmest times and places and may be seeps of salty water. A source of water in a non-polar location is needed to support a future human presence on Mars, but Planetary Protection will be a challenge (or impossible). Jupiter’s moon Io is the ideal natural laboratory to understand groundbreaking volcanism and tectonism. Very large-scale energetic processes that have shaped the planets are active today on Jupiter’s moon Io, so this is the best place to study these processes. Is there active venting on Europa? We don’t know (yet) because we haven’t looked with the proper combination of resolution (<20 km), phase angle, and coverage. Understanding active geologic and atmospheric processes and how they affect spectral signatures will determine the interpretability of exoplanet spectra and inform the search for ET life. However, the most amazing planetary habitability experiment in this arm of the galaxy is Earth.