Post by Dr Matthew Chojnacki
Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN
The 2011 arrival of the Mars Exploration Rover Opportunity at the western rim of Endeavour crater (Cape York) provided an excellent opportunity to look for aeolian dune activity over a multi-season time span (Figs. 1 & 2) and compare them to the decade-long orbital observations documented at that site (Chojnacki et al., 2011). Here are some of the first images from a dedicated Pancam campaign to monitor these dunes and to document any aeolian surface changes (also see Chojnacki et al., 2012).
The western dune field (Image. 1) consists of 26 barchans and one large barchanoid compound dune (Image. 2). The ~20 resolvable duneforms, informally named the “Greeley Dune Field” after late planetary scientist Ronald Greeley, are 6–8 km downwind from Cape York.
Opportunity has been monitoring the dune field over the past season (southern autumn, Ls 6–98°) and has detected a shift in a dark streak emulating from the northeastern most barchan dune. This shifting dark streak was observed by previous studies (Chojnacki et al., 2011; Sullivan et al., 2005; and Geissler et al., 2008) and is known to switch from a southern summer southerly wind regime to a southern winter northwesterly wind regime. Future Pancam monitoring of the dark streak may be able to better constrain dark streak activity.
Additional evidence for aeolian activity is found between super resolution sub-frames with observations of dust-lifting events south of the dune fields (Image 4). Future Pancam observations will attempt to monitor any dune deflation, dark streak activity, and dust-lifting events.
Acknowledgments: I would like to thank the Athena Science Team, Pancam operation support, Mark Lemmon for his animated Pancam movie, and the MRO team for their wonderful data.
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