COMPARISON OF VENTIFACT ORIENTATIONS AND RECENT WIND DIRECTION INDICATORS NEAR THE MARS 2020 OCTAVIA E. BUTLER LANDING SITE ON MARS

Wind-abraded rocks and aeolian bedforms have been observed at the Mars 2020 Perseverance landing site, providing evidence for recent and more ancient wind directions. We measured the orientations of various eolian features using Perseverance imaging data to infer the orientation of the winds that formed them, and compared these azimuths with orbital observations, climate model predictions, and wind data acquired by the Mars Environmental Dynamics Analyzer [1]. The Mastcam-Z [2] and navigation cameras [3] have acquired stereo images that have been used to derive high-resolution digital terrain models (DTMs). We used the DTMs to measure the 3-dimensional orientation of flutes, regolith wind tails, and other aeolian features. One or two flutes were measured on each of 13 ventifacts in the DTM derived from a Mastcam-Z stereo panorama acquired on Sol 3, yielding a mean azimuth of 294° ± 7° (wind from the west-northwest). However, similar measurements of 16 regolith wind tails indicate that recent sand-driving winds have been blowing from the east-southeast, nearly the opposite direction (mean azimuth = 112° ± 17°). Atmospheric modeling generally predicts net annual sand transport from the east-southeast at present [4], consistent with Perseverance regolith wind tail and orbital observations [5]. The orientation of ventifact flutes thus indicates that they were formed under a different climate regime. Differences in orientations of recent and paleo-wind indicators have been noted at other Mars locations [6] and may be a result of major orbital/axial changes that can cause significant changes in atmospheric circulation [7]. Such observations may thus provide insight into the past climate in this region.

[1] Rodriguez-Manfredi, J.A. et al. (2021), Space Sci. Rev. 217, doi.org/10.1007/s11214-021-00816-9.

[2] Bell, J. F. et al. (2021), Space Sci. Rev. 217, doi:10.1007/s11214-020-00755-x.

[3] Maki, J. N. et al. (2021), Space Sci. Rev. 216, doi:10.1007/s11214-020-00765-9.

[4] Newman, C. E. et al. (2021), Space Sci. Rev. 217, doi:10.1007/s11214-020-00788-2.

[5] Day, M. and T. Dorn (2019), Geophys. Res. Lett. 46, doi:10.1029/2019GL-82218.

[6] Laity, J. E. and N. T. Bridges (2008), Geomorphology, doi:10.1016/j.geomorph.2008.09.014.

[7] Fenton et al. (2018), J. Geophy. Res. 123, doi.org/10.1002/2017JE005503.