This image taken by the Mars Reconnaissance Orbiter spacecraft shows sedimentary rock and sand within Danielson Crater, an impact crater about 42 miles or 67 kilometers in diameter, located in the southwest Arabia Terra region of Mars.
The rock was formed millions or billions of years ago when loose sediments settled into the crater, one layer at a time, and were later cemented in place. Cyclical variations in the sediment properties made some layers more resistant to erosion than others. After eons, these tougher layers protrude outward like stair steps. Across these steps, the winds have scattered sand (typically appearing darker and less red, i.e. “bluer” in contrast-enhanced color), giving rise to the zebra stripe-like patterns visible here.
This image completes a stereo pair over this location, which will allow measurement of the thicknesses of these sedimentary layers. The layer thicknesses and how they vary through time can provide some insight into the processes, possibly linked to ancient climate, that deposited the layers so long ago.
The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. (The original image scale is 57.2 centimeters [22.5 inches] per pixel [with 2 x 2 binning]; objects on the order of 172 centimeters [67.7 inches] across are resolved.) North is up.
图片来源:NASA/JPL-Caltech/University of Arizona