Science Background

Aeolian sand dune systems are known to occur on four bodies in our solar system (Earth, Mars, Venus, and Titan). Aeolian bedforms have even been observed on airless bodies with transient atmospheres (e.g. comets). Despite the range of atmospheric pressures, composition and gravity, many of the dune forms appear similar, albeit with notable differences in dune scale and composition for some bodies.

The high volume of data returned recently from planetary surfaces (especially Mars) has triggered a new era in planetary studies. Consequently, researchers are currently in the exploration and discovery phase of extra-terrestrial dune systems. Whereas the majority of these data are obtained from space-borne platforms, landers and rovers also return images captured on the surface. The Mars Science Laboratory (Curiosity) is currently traversing the edge of a dune field located in Gale Crater. Curiosity has and will continue to take in situ samples for compositional and grain-size analysis, thus providing ground-truth for all of the remote sensing data acquired.

Much of our understanding of planetary dune systems comes from the application of Earth analogs. While the majority of analog sites have been located in arid and semi-arid environments, the addition of subaqueous dunes as analogs will be a new focus. In addition, important findings have resulted from wind tunnel experiments and modeling studies that employ the different atmospheric, orbital, and gravitational parameters pertinent to each of the bodies.

Each new mission utilizes instruments with higher spatial and spectral resolution. These produce a stream of new data that sometimes deliver unexpected results (e.g. the discovery of a strong sulfate signature in the North Polar dunes on Mars). Earth analogs become increasingly useful as discoveries of the similarities and differences in dune systems on the different bodies continue to emerge. In some cases these analogs find renewed application on Earth. For example, Schatz et al. use the morphology of oil-soaked barchans in Saudi Arabia to suggest that dune cementation/induration may cause the unusual elliptical shape of some barchans in the North Polar region on Mars. In turn, cohesion is invoked to explain the formation of linear dunes in China and on Titan.

The study of dunes within our solar system requires research collaborations across many fields of expertise to achieve significant results. A small, well-focused dunes workshop provides that opportunity.