Mystery Mounds
Mystery Mounds
PSP_008778_1685  Science Theme: Hydrothermal Processes
This image was targeted because a previous MOC image (R1100035) showed a distinctive field of mounds on the floor of an ancient, large, filled-in crater.

The origin of the mounds was unclear, so we hoped that a HiRISE image with higher resolution and color would solve the mystery. The HiRISE image shows much more detail on the mounds and other rough textures, indicating that this is an eroded bedrock surface, perhaps exposed by removal of an overlying layer of fine-grained materials by the wind.

But how did the rocks form, and why did they erode onto mounds? It could have been lava or impact ejecta or fluvial sediments, perhaps altered and indurated by groundwater. The mounds could be due to how it was deposited—like hummocky impact ejecta—or how it was indurated. In other words, we haven't solved the mystery!

Yet we may get new clues from future images of similar terrains in places where the origin is more interpretable, or from other datasets such as the mineral content determined by CRISM.

Written by: Alfred McEwen  (16 July 2008)
Acquisition date
10 June 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
265.2 km (164.8 miles)

Original image scale range
26.6 cm/pixel (with 1 x 1 binning) so objects ~80 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
61°, with the Sun about 29° above the horizon

Solar longitude
83.5°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  42.5°
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   (754MB)

IRB color
map-projected   (349MB)

Black and white
map-projected  (341MB)
non-map           (433MB)

IRB color
map projected  (122MB)
non-map           (322MB)

Merged IRB
map projected  (174MB)

Merged RGB
map-projected  (177MB)

RGB color
non map           (284MB)
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.