RECENT ADVANCES IN MARTIAN AEOLIAN SCIENCE

Since the early 1970s, seven orbital and seven landed spacecraft have contributed to a boom in geological studies of Mars. This wealth of data has revealed much about the past of the Red Planet; one major discovery has been that aeolian processes have dominated landscape evolution on Mars over the past 3 Gyr. Many aeolian features and phenomena are familiar to those who study terrestrial deserts: sand dunes and drifts, both sand and coarse-grained ripples, wind tails, ventifacts, yardangs, sandstones, dust devils, and dust storms. Other features and phenomena appear to be (or are perhaps nearly) unique to Mars: transverse aeolian ridges, periodic bedrock ridges, bedforms made from dust, wind streaks, fine-grained dust mantles (possibly similar to loess), dust devils >10 km in height, dust devil tracks, and planet-encircling dust events. Most aeolian landforms are ancient, indurated, eroded, and in places only recently exhumed. However, actively migrating bedforms and continuous dust storm production indicate present-day vigorous wind activity, despite Mars’ currently low air density.

The amount of spacecraft data and the development of methods used by the terrestrial aeolian community have led to numerous recent advancements in our understanding of aeolian processes on Mars. Identification of aeolian facies in several locations on the planet has suggested that aeolian deposition has contributed significantly to the sedimentary rock record. Similarly, vast yardang fields attest to the influence of aeolian erosion on landscape development. The morphology and composition of modern dunes has been studied to constrain the incident wind regime, sand mineralogical maturity, and sand provenance. Some of these dunes may be among the few locations on Mars where liquid water currently forms, making them relevant to astrobiological investigations. Models of sediment transport and bedform dynamics have successfully described unusual martian dunes by considering multimodal wind regimes and the influence of induration. A deeper understanding of fluid and impact saltation thresholds on Mars may explain a long-standing discrepancy between modeled wind speeds and observations. These findings and many more underscore the rapid advancement of planetary aeolian science in the last decade.