Dark Patches Formed by Craters
Dark Patches Formed by Craters
ESP_071661_1570  Science Theme: Geologic Contacts/Stratigraphy
In the ancient past, this area of Mars was bombarded by impactors, forming craters of various sizes in the light-toned material. Some time after that, a darker material blanketed and covered the field, filling in the craters. Eventually, that blanketed material itself became rock. Long after that, erosive forces (likely wind) acted in this area removing both dark and light-toned material, like an archeologist using a brush to reveal buried structures.

What we see today are a variety of dark circular features that are the remains of the layer that has been eroded back from the walls of the craters that formed them. In some cases, the crater rim is eroded and just a circular dark patch stands on a brighter exposure of rock.

Studying the thickness and characteristics of the dark layer might help scientists learn more about the processes that deposited the material, as well as those that eroded it.

Written by: Ross Beyer (narration: Tre Gibbs)  (14 March 2022)

This is a stereo pair with ESP_071806_1570.
Acquisition date
09 November 2021

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
259.7 km (161.4 miles)

Original image scale range
52.6 cm/pixel (with 2 x 2 binning) so objects ~158 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
70°, with the Sun about 20° above the horizon

Solar longitude
124.6°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  40.6°
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NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.