Protonilus Mensae Glaciation
NASA/JPL/UArizona
Protonilus Mensae Glaciation
ESP_068044_2240  Science Theme: Glacial/Periglacial Processes
During periods in Mars’ history when the planet had greater axial tilt, shifts in atmospheric circulation may have favored the extensive accumulation of snow in some locations. Protonilus Mensae is just such a site of extensive glaciation.

We can see a flow of material through the valleys between a complex of small mesas. Streamlines and flow fronts appear as subtle ridges. Some ridges appear perpendicular to the mesas indicating flow direction. Others appear concentric to the mesas and parallel to the valleys, where debris and now-underlying ice bunched up and moved down valley.

Deflation of the ice has led to a rich collection of small-scale features. Polygonal patterns of fractures and fissures may be related to a combination of thermal contraction cycles and overall subsidence of the surface. Larger fractures may be glacial crevasses, caused by differential flow rates in the underlying ice. Other more complex patterns of swirled pits and hummocks may result from the continual loss of unstable ice in the present-day dry climate.

Written by: Mike Mellon (narration: Tre Gibbs)  (15 April 2021)
 
Acquisition date
31 January 2021

Local Mars time
14:38

Latitude (centered)
43.600°

Longitude (East)
51.628°

Spacecraft altitude
297.9 km (185.2 miles)

Original image scale range
30.0 cm/pixel (with 1 x 1 binning) so objects ~90 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
6.9°

Phase angle
51.9°

Solar incidence angle
57°, with the Sun about 33° above the horizon

Solar longitude
356.5°, Northern Winter

For non-map projected images
North azimuth:  96°
Sub-solar azimuth:  324.9°
JPEG
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

JP2
Black and white
map-projected   (728MB)

IRB color
map-projected   (401MB)

JP2 EXTRAS
Black and white
map-projected  (310MB)
non-map           (348MB)

IRB color
map projected  (109MB)
non-map           (272MB)

Merged IRB
map projected  (195MB)

Merged RGB
map-projected  (189MB)

RGB color
non map           (262MB)
ADDITIONAL INFORMATION
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products
HiView

NB
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

USAGE POLICY
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

POSTSCRIPT
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.