Although actively-forming gullies are common in the middle latitudes of Mars, there are also pristine-looking gullies in equatorial regions.

In this scene, the gullies have very sharp channels and different colors where the gullies have eroded and deposited material. Over time, the topography becomes smoothed over and the color variations disappear, unless there is recent activity.

Changes have not been visible here from before-and-after images, and maybe such differences are apparent compared to older images, but nobody has done a careful comparison. What may be needed to see subtle changes is a new image that matches the lighting conditions of an older one. Equatorial gully activity is probably much less common—perhaps there is major downslope avalanching every few centuries—so we need to be lucky to see changes.

MRO has now been imaging Mars for over 16 years, and the chance of seeing rare activity increases as the time interval widens between repeat images.

ID: ESP_072612_1685
date: 22 January 2022
altitude: 263 km

https://uahirise.org/hipod/ESP_072612_1685
NASA/JPL-Caltech/UArizona
#Mars #science #NASA