The Velvety Blue Dunes of Melas Chasma
The Velvety Blue Dunes of Melas Chasma
ESP_055322_1680  Science Theme: Aeolian Processes
This color-infrared image shows sand dunes in Melas Chasma, located within the Valles Marineris canyon system. The dark-blue and purple colors indicate coarse-grained sands that are comprised of basalt, an iron and magnesium-rich volcanic rock that formed from cooled lava millions of years ago when volcanism was an active process on Mars.

Migrating sand dunes often lead to the erosion and excavation of underlying material; regions where there are active dune fields are ideal places to search for exposed bedrock. Repeated imaging of dunes may also show changes that provide evidence for active surface processes related to wind patterns and climate.

Written by: Sarah Simpson, Alyssa Werynski, Jennifer Newman, Livio Tornabene (audio: Tre Gibbs)  (1 October 2018)
Acquisition date
16 May 2018

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
261.0 km (162.2 miles)

Original image scale range
26.5 cm/pixel (with 1 x 1 binning) so objects ~79 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
55°, with the Sun about 35° above the horizon

Solar longitude
176.4°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  17.5°
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   (707MB)

IRB color
map-projected   (445MB)

Black and white
map-projected  (350MB)
non-map           (387MB)

IRB color
map projected  (141MB)
non-map           (397MB)

Merged IRB
map projected  (175MB)

Merged RGB
map-projected  (169MB)

RGB color
non map           (414MB)
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.