DID THEY* PERSIST...OR INSTEAD GET INUNDATED, THEN MEANDER, AND FINALLY BE BLOWN BY THE WIND? FIRST-HAND DISCOVERIES IN FLOOD, FLUVIAL AND AEOLIAN PLANETARY GEOLOGY

This solicited first-hand account of exciting discoveries in planetary geology begins with the discovery – under the advisorship of the 2019 Gilbert awardee – of extremely late Amazonian outflow channels on Mars. Impelled by the striking streamlined forms revealed by early Mars Orbital Camera images, this graduate school work expanded into studies of flooding on three planetary bodies and today forms the foundation for continued investigations into those same Martian flood channels, for which that former graduate student is now the advisor. Data from the Gilbert winner’s High Resolution Imaging Science Experiment (HiRISE) was coeval a shift in the author’s scientific focus from flood to fluvial geomorphology and enabled the discovery of ancient meandering river deposits on Mars. Sadly, this discovery was dismissed by some institutional faculty colleagues because meandering on early Earth is not well-documented and is broadly correlated in time with the rise of plants. Happily, the compensatory result was the spawning of field investigations to understand how meandering could have occurred without plants. It also led more recently into the technique of geologic mapping, the modest success of which suggests that, even as a senior scientist, one can teach oneself new tricks (with the invaluable help of a few good graduate students). The discovery of the alien-but-Earth-like nature of geologic processes on the surface of Titan, revealed in part through the Gilbert awardee’s work on the Cassini mission, opened up opportunities to expand fluvial analyses on Earth and Mars into cryogenic conditions, as well as to launch into experimental investigations, including planetary wind tunnel studies. Hampered by various challenges, including pervasive ignorance of wind tunnel studies by the author, the results of this wind tunnel work saw the light roughly a decade after the initial proposal, presenting a story either of persistence as per a theme of this session or simply of poor judgment with regard to career-building. That Titan aeolian work, however, did encourage contemplation of the broader concept of aeolian studies and led to aeolian investigations on Mars. Fittingly, these on-going investigation are – once again – enabled by this year’s Gilbert winner, in the form data from the HiRISE instrument.