Orbital observations of contemporary dune activity in Endeavor crater, Meridiani Planum, Mars

Although aeolian landforms are pervasive on Mars, evidence for contemporary activity has been limited. The next major campaign for the Mars Exploration Rover Opportunity is the investigation of the ∼20 km diameter Endeavor crater, ∼6 km to southeast of the rover's position as of December 2010. We present evidence from orbital imagery that eight aeolian bed forms (∼14,000 m²) in Endeavor crater have been active within the past decade (2001-2009), at a spatial scale that should be directly observable by Opportunity from the crater rim. Two dunes appear to show translational migration (∼10-20 m), but all dunes indicate erosion to be the dominant process with up to 100% sediment removal. Thermophysical properties of these dunes are consistent with very fine to fine sand sizes, the particle sizes most easily moved by the Martian atmosphere. The dunes that show the most surface change have a rippled appearance without well-defined slip faces. Based on their morphology (elliptical shape), we classify them as dome dunes. Mesoscale atmospheric modeling is employed to provide insight into the atmospheric forcing of this aeolian system. The major wind regimes from modeling are consistent with observations of wind streaks, sand streamers, ripples, and slip faces of regional dune fields although modeled wind speeds are insufficient to move sand. The translation and erosion of these dunes constitutes the largest contemporary movement of sand-sized sediment reported on Mars to date and demonstrates that Endeavor crater has been subject to wind profiles exceeding the threshold velocity at the surface (daily/seasonally and/or episodically) in the recent past.