contributed by Ken Herkenhoff
I like this part of the Sol 3 Mastcam-Z panorama, showing the rocket “blast zone” on the north side of the rover, for a couple reasons. First, it shows the effects of the plume from the rockets that slowed Perseverance to a stop just above the Martian surface. It illustrates one of the reasons the “sky crane” maneuver was used to place Curiosity and Perseverance on Mars: the descent rockets are powerful enough to blow soil off the surface, potentially damaging the rover. Indeed, one of the wind sensors on Curiosity was destroyed during landing in 2014 by material thrown into the air by the rocket plume. If the rover had not been lowered below the descent stage by the sky crane, the damage to the vehicle would have been even more severe.
Second, this part of the panorama shows that the rocket plume removed bright material from the gray rocks in the foreground. The bright coating was completely removed from the rocks just below right of center, while less of the coating was removed from rocks toward the left and in the background. This shows that the coating is not very resistant to wind erosion, but stronger than a loose coating of airfall dust. Such a dust coating would be expected to cover the entire surface, but the darker material between bright rocks in the background shows that bright dust has not completely covered the surface here. So while the bright rock coating may be composed mostly of dust, something has at least partly cemented it to the surface of the dark rocks.
February 21, 2021