Squiggles in Hellas Planitia
NASA/JPL-Caltech/UArizona
Squiggles in Hellas Planitia
ESP_051770_1345  Science Theme: Seasonal Processes
At around 2,200 kilometers in diameter, Hellas Planitia is the largest visible impact basin in the Solar System, and hosts the lowest elevations on Mars’ surface as well as a variety of landscapes. This image covers a small central portion of the basin and shows a dune field with lots of dust devil trails.

In the middle, we see what appears to be long and straight “scratch marks” running down the southeast (bottom-right) facing dune slopes. If we look closer, we can see these scratch marks actually squiggle back and forth on their way down the dune. These scratch marks are linear gullies.

Just like on Earth, high-latitude regions on Mars are covered with frost in the winter. However, the winter frost on Mars is made of carbon dioxide ice (dry ice) instead of water ice. We believe linear gullies are the result of this dry ice breaking apart into blocks, which then slide or roll down warmer sandy slopes, sublimating and carving as they go.

The linear gullies exhibit exceptional sinuosity (the squiggle pattern) and we believe this to be the result of repeated movement of dry ice blocks in the same path, possibly in combination with different hardness or flow resistance of the sand within the dune slopes. Determining the specific process that causes the formation and evolution of sinuosity in linear gullies is a question scientists are still trying to answer. What do you think causes the squiggles?



Written by: Matthew Maclay (audio: Tre Gibbs)  (23 October 2017)

This is a stereo pair with ESP_051836_1345.
 
Acquisition date
12 August 2017

Local Mars time
14:50

Latitude (centered)
-45.304°

Longitude (East)
67.213°

Spacecraft altitude
257.9 km (160.3 miles)

Original image scale range
26.4 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
Equirectangular

Emission angle
12.6°

Phase angle
81.9°

Solar incidence angle
74°, with the Sun about 16° above the horizon

Solar longitude
46.3°, Northern Spring

For non-map projected images
North azimuth:  96°
Sub-solar azimuth:  53.6°
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Black & white is 5 km across; enhanced color about 1 km
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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-Caltech/UArizona

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.