Waxing and Waning Winds
Waxing and Waning Winds
ESP_076986_1375  Science Theme: Aeolian Processes
The Hellespontus Montes is a rugged mountain range located on the western rim of one of the largest impact basins in the Solar System: Hellas Basin.

The 7-kilometer depth of Hellas and its location in the Southern Hemisphere form an active atmospheric system that directly impacts local landscape evolution. Hellespontus has a large accumulation of sand dunes and other wind-created bedforms that have been migrating on a continual basis since HiRISE began imaging Mars.

A dune’s steepest area, called a “slip face,” indicates the down-wind side of the dune and its migration direction as driven by local winds. At this location, there are many dunes influenced by eastward winds that were draining into Hellas. Meanwhile, other locations show that migration had shifted towards the opposite direction to the west.

In certain cases, we see these opposing dune directions in proximity. The complex patterns are not due to winds that are constant in magnitude or direction, but rather they wax and wane over the course of the Martian year.

Written by: Matthew Chojnacki  (5 April 2023)
Acquisition date
29 December 2022

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
253.8 km (157.8 miles)

Original image scale range
51.0 cm/pixel (with 2 x 2 binning) so objects ~153 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
56°, with the Sun about 34° above the horizon

Solar longitude
1.3°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  44.9°
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
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RGB color
non-map projected

Black and white
map-projected   (341MB)

IRB color
map-projected   (191MB)

Black and white
map-projected  (178MB)
non-map           (254MB)

IRB color
map projected  (91MB)
non-map           (214MB)

Merged IRB
map projected  (346MB)

Merged RGB
map-projected  (318MB)

RGB color
non map           (204MB)
10K (TIFF)

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’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.