Weathering, erosion and landscape processes on Mars identified from recent rover imagery, and possible Earth analogues

Abstract

The search for evidence of water on Mars has been a principal objective during NASA's current 2003 – 2004 series of Mars Exploration Rover (MER) missions. The missions were designed to explore the Martian surface for signs, past or present, of liquid water. However, some attention has also been given to other erosional and landscape processes that may be inferred from the abundance of images now available. On Earth, the main physical weathering processes are frost weathering, salt weathering, and wetting and drying. These processes commonly result in exfoliation, spalling, and granular disintegration. Some of the forms present on the Martian surface also suggest that chemical weathering has taken place. There are also diverse aeolian processes that, in addition to dune forms, result in small abrasion forms on exposed rocks. NASA's recent MER missions imaged numerous micro- and meso-scale features on the surface of the planet, many resembling the results of these terrestrial processes. Using imagery collected by NASA's Spirit and Opportunity rovers, we describe and categorise features using a basic geomorphic classification and compare a number of these features with possible Earth analogues. Our comparisons show that many of the features on the surface of Mars could be formed by processes common on Earth. We conclude that in most cases it is not necessary to seek complex or exotic processes to explain Martian geomorphology.