MODELING IMPACT BLAST WINDS ON MARS: THE FORMATION OF PERMANENT WIND STREAKS

Some bright wind streaks on Mars, revealed in THEMIS nighttime images, are thought to be the result of impact-generated winds that can extend great distances from the parent crater (e.g. [1]). These permanent wind streaks are the result of wind vortices that mobilize surface material and cause scouring of the surface. Here, we demonstrate the initial simulations and experiments for the blast wind study using the CTH shock physics code developed at Sandia National Laboratories. CTH is an Eulerian shock physics analysis code with several applications, among which are planetary impact simulations (e.g. [2-3]). Previous studies verified that both the Peak Pressure Method and the Final Temperature Method may be used to determine melting and vaporization of material in CTH (e.g. [4]). While the Peak Pressure Method is commonly used in the planetary community [5], the Final Temperature Method is useful to explore impact processes in more detail. We use both of these methods to study the production and expansion of melt and vapor in a three dimensional simulation of an impact on Mars. The dunite projectile impacted at 45° and 12 km/s into a (1) basalt target and (2) a basalt target overlain by 500 m of ice to enhance vaporization effects. Our initial results show that, as expected, the ice enhanced vaporization. We found that the vapor blast, which we suggest is related to the blast winds, may become coupled to the surface with velocity magnitudes of hundreds of meters per second. Future work will refine the impact model and incorporate laboratory experiments performed at the NASA Ames Vertical Gun Range.

[1] Schultz, P.H. & Quintana, S. (2013), LPSC 44, Abs. #2697

[2] Crawford, D. A. (2011), LPSC 42, Abs. #2112.

[3] Schultz, P. H. & Wrobel, K.E. (2012), JGR-Planets 117.

[4] Quintana, S., et al. (2013), LPSC 44, Abs. #1733.

[5] Pierazzo et al. (1997), Icarus 127.