Saharan Dust Devil Tracks: Mars Analog Field Study Areas

Dust devil tracks are seasonal erosional albedo patterns left by the passage of active dust devils (dry convective atmospheric vortices). Nearly ubiquitous features on the surface of Mars, dust devil tracks are rarely identified on Earth (Rossi et al., 2004; Whelley et al., 2007). Hundreds of tracks have been identified in northern Africa from publicly available images on Google Earth. Track locations include the putative Kebira impact structure (24.67 N, 024.97 E) on the Egypt-Libya border, in southern Libya (22.89 N, 018.50 E) ~50 km north of Chad, and within a few km (north and south) of the Libya-Niger border (23.22 N, 013.40 E). Terrestrial tracks range in size from 2 to ~20 m wide and 0.1 to 10 km compared to their martian equivalent ranges of 10 to ~200 m wide (Balme et al., 2003) and from a few meters to tens of kilometers in length (Cantor et al., 2006). African dust devil tracks could provide accessible analogs to tracks and seasonal dust storms observed on Mars, such as those observed in Gusev Crater by the Mars Exploration Rover, Spirit. Key questions to be addressed include: what surface materials promote or prohibit tracks? How much sediment is removed in a dust devil event? How are tracks preserved or destroyed? How rapidly do tracks disappear over time? What role do seasonal dust storms play in dust deposition? Terrestrial dust devil track sites could provide valuable clues for the conditions and mechanisms driving seasonal dust devil sediment transport on Earth and Mars today.