Geophysical and remote sensing study of terrestrial planets
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The overarching theme of this dissertation is the study of the evolution of terrestrial planets and its effect on surface processes and planetary habitability. In many regards, planetary habitability is an enthralling yet obscure topic because our understanding is limited by our terrestrial experience. The utmost necessity for habitability, based on terrestrial experience and general chemical principles, is water. The dissertation provides key spectroscopic evidence for contemporary liquid water on Mars. Pure water is highly unstable on Mars, so any water on the surface would likely be salty. The spectral data from Mars further provides evidence for hygroscopic salts called perchlorates that may be aiding in the formation of these present day brine streaks on Mars. Similar hygroscopic salts are found elsewhere on Mars; in every instance their presence occurs near known ice deposits, ancient sedimentary rocks or modern day brines. The important role of these hygroscopic salts in the present and past Martian water cycle and on habitability is discussed. Change is an inevitable part of natural processes, and nowhere is it manifested more exuberantly than in planetary landscapes. Planets evolve, and the corroboration of change is evident in surface features. An effort to understand the evolution of terrestrial planets in our own solar system, to better understand the formation and evolution of terrestrial planets elsewhere in the universe, is the second central theme of the dissertation. Specifically, by using the gravity data from the orbiters, a series of predictions about the InSight landing site is made. These predictions will test the validity of various methodologies and help constrain the radiogenic content of the Martian crust. In the long term, the measurements from InSight will help answer the evolutionary course Mars took, and what effect higher heat flow during the early stage of its history may have had on the loss of liquid water from the surface.