Rock Abrasion and Landscape Modification by Windblown Sand as Documented by the Msl Curiosity Rover

Introduction Mars is a dry planet, with actively blowing sand in many regions [1-5]. In the absence of stable liquid water and an active hydrosphere, rates of chemical weathering are slow, such that aeolian abrasion is a dominant agent of landscape modification where sand is present and winds above threshold occur at sufficient frequency. Reflecting this activity, ventifacts, rocks that have been abraded by windborne particles, are common on the Martian surface. They provide invaluable markers of the Martian wind record and insight into climate and landscape modification. Yardangs are also indicative of sand abrasion, but, given their size of several meters to kilometers, reflect larger scale wind patterns. The Mars Science Laboratory (MSL) Curiosity payload is well suited for studying ventifacts and modern wind patterns which are relevant for understanding current and past abrasion/wind conditions [6]. The rover mast cameras, Navcam, Mastcam, and the ChemCam Remote Micro Imager (RMI) provide images of varying coverage and spatial scale. In particular, the Mastcam M100 (right eye) and ChemCam Remote Micro Imager (RMI), with pixel scales 74 [7] and 19.6 µrad [8-9], provide fine details of rock textures. The ChemCam Laser Induced Breakdown Spectrometer (LIBS) gives elemental composition as a function of depth down to ~10s of µm beneath rock surfaces, penetrating the outer dust layer and providing clues to the presence of any rock coating or rind [11,12]. The Rover Environmental Monitoring Station measures wind speed and direction, pressure, relative humidity, air temperature, ground temperature, and ultraviolet radiation, with 1 Hz sampling for over 5 min every hour and periodic (generally daily) observations for durations of an hour or more [13]. Finally, the HiRISE camera on the Mars Reconnaissance Orbiter provides 25 cm pixel-scale images which are used to compare MSL results to regional scale geology and topography, including the presence and inferred formative wind directions of dunes and yardangs. Here we provide the latest measurements and interpretations of the rock abrasion record in Gale Crater, adding to the data that was previously analyzed through Sol 100 [6]. Methods Ventifacts through Sol 438 were identified in systematic searches through all M100 mosaics and associated RMI