GALE CRATER AND IMPACT PROCESSES FROM THE MARS SCIENCE LABORATORY PERSPECTIVE INCLUDING ANALYSIS WITH VIRTUAL REALITY TECHNOLOGY

Curiosity has been exploring the ~150 km diam. Gale crater for 5 Earth years, 1756 Sols, and has driven 17 km. Impact processes were observed with the imagers on Curiosity including NavCam, MastCam, MAHLI and the ChemCam remote micro imager (RMI), which is the highest resolution camera for distance observations. Most of the images of small craters were taken in the vicinity of the rover during routine surveys by NavCam and MastCam, as foreshortening and topography makes it difficult to target features with MastCam and RMI beyond about 100 m from the rover. We are now analyzing the shape and rim characteristics of these craters using newly available Virtual Reality (VR) technology, including the Microsoft Hololens headset. The early part of the mission was spent on Bradbury Rise (Sol 0 – 124, 301- 703) and in Yellowknife Bay (Sols 124 – 300). Small craters on Bradbury Rise are heavily degraded with subdued rims, shallow (d/D <= 0.1) sand to gravel filled depressions, lacking ejecta blankets/blocks or other diagnostic features (shatter cones, impact breccias, etc.). Yellowknife Bay craters exhibit the same morphology, lacking even upturned rims, consistent with the more erodible 'mudstone' target material. A few fresh craters with continuous ejecta exist within Gale crater, but all are beyond MSL's nominal traverse path, although some long baseline stereo RMI imaging has been accomplished of the Slangnos crater (~ 4 km diam.). Beginning about Sol 700, Curiosity reached the Pahrump Hills and Mount Sharp units, especially the Murray formation, which contains only a few small craters. The minimum size of ~0.6 m is consistent with results from the MER rovers and suggests that the atmospheric density has been relatively low in recent eons. There is also a dearth of evidence for exhumed craters emplaced during deposition, consistent with statistical analysis suggesting that even with low deposition rates (~10 – 100 microns/yr), exhumed craters should be rare in outcrop. The extensive high resolution images of the surface by MAHLI and RMI have turned up essentially no evidence for impactites including shatter cones, except maybe some impact spherules. Impact breccias are also absent, although some enigmatic deposits could be impact related.