Monitoring Active Gullies
Monitoring Active Gullies
ESP_063775_1295  Science Theme: 
Gullies are common on steep slopes of many impact craters on Mars. When gullies were first observed, there was a lot of excitement surrounding them because similar features form on Earth through the action of liquid water.

However, liquid water is currently unstable on the surface of Mars. Long-term observations have prompted many scientists to question a liquid water origin for the gullies, and alternative ideas have been suggested. These include flows of salt-rich (briny) water, as the salt would allow water to be liquid under lower temperatures than those for pure water. Also “dry” processes, which do not require the action of liquid water at all.

Monitoring of gullies by HiRISE could help scientists better understand the conditions where the gullies are active, and in doing so, help understand how they form.

Written by: M. Ramy El-Maarry (narration: Tre Gibbs)  (2 April 2020)
Acquisition date
04 March 2020

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
250.6 km (155.8 miles)

Original image scale range
50.2 cm/pixel (with 2 x 2 binning) so objects ~151 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
77°, with the Sun about 13° above the horizon

Solar longitude
161.0°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  36.4°
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
map projected

RGB color
non-map projected

Black and white
map-projected   (187MB)

IRB color
map-projected   (103MB)

Black and white
map-projected  (69MB)
non-map           (127MB)

IRB color
map projected  (27MB)
non-map           (123MB)

Merged IRB
map projected  (199MB)

Merged RGB
map-projected  (176MB)

RGB color
non map           (109MB)
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products

IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:
NASA/JPL/University of Arizona

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.