Recent Gullies in Equatorial Valles Marineris
Recent Gullies in Equatorial Valles Marineris
ESP_072612_1685  Science Theme: Mass Wasting Processes
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.

Written by: Alfred McEwen  (20 April 2022)
Acquisition date
22 January 2022

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
263.1 km (163.5 miles)

Original image scale range
from 26.5 cm/pixel (with 1 x 1 binning) to 53.1 cm/pixel (with 2 x 2 binning)

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
60°, with the Sun about 30° above the horizon

Solar longitude
161.8°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  21.6°
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non-map           (308MB)

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Black & white is 5 km across; enhanced color about 1 km
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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.