Planetary Science Seminar spring-2016

The hydro-geomorphic history of Gale crater

The Curiosity rover was sent to Gale crater where we are in a unique position to determine the extent to which topography can tell us the evolutionary history of a place on another planet, since our hypotheses can actually be tested with ground-based observations. Here I report results of rover-based investigations coupled with satellite-derived information, which suggests alternating wet-and-dry periods of varying duration and magnitude. Sedimentary sequences discovered along the rover’s traverse show evidence for an ancient lake early in Gale’s history, but the size and duration of this lake is difficult to discern from the stratigraphy. Eventually, there was a period of drying and infilling of the crater with wind-derived sediments, before erosion formed the central mound. Post-formation of the mound there were a sequence of large lakes (the deepest being 700 m) that required at least 30 m/yr of runoff to maintain the last lake stand. After the lakes disappeared, reduced hydrologic activity continued, evidenced by a period of fan building (including the Peace Vallis fan). This sequence of events suggests an episodic shift through time from relatively wet regional conditions to a drier environment with local runoff.