A T Party on Mars
A T Party on Mars
ESP_062151_2540  Science Theme: Seasonal Processes
The dunes of Mars clearly sent out an invitation to a “T Party,” but it looks like none of us were invited. Forming a veritable maze of sand and rock, these unusually shaped dunes are located in the north polar region.

The shape and the form of the dunes serve as weathervanes. In crescent or “barchan” dune forms, the pointed tips of the sand dunes align with the dominant wind direction. The sand grains move with the wind, progressing the dunes forward over time. The T Party dunes are similar to “barchan” dunes, but they deviate from the characteristic crescent shape, thus it is less clear which direction is indicated. They may be suggesting varying wind conditions and perhaps the dunes are in the process of changing directions.

These polar dunes form as piles of basaltic sands that are covered with bright carbon dioxide frost as the Martian winter descends every year. In this early northern summer image, the dunes have thawed, the frost has sublimated to gas, and the underlying dark sand is exposed. Small ripples on the dunes and the underlying polygonized surface and boulders are also visible in this enhanced color cutout.

Written by: Leah Sacks, Livio Leonardo Tornabene, Vidhya Ganesh Rangarajan, and Chimira Andres  (9 February 2020)

Acquisition date
30 October 2019

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
317.8 km (197.5 miles)

Original image scale range
31.8 cm/pixel (with 1 x 1 binning) so objects ~95 cm across are resolved

Map projected scale
25 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
53°, with the Sun about 37° above the horizon

Solar longitude
99.9°, Northern Summer

For non-map projected images
North azimuth:  101°
Sub-solar azimuth:  326.1°
Black and white
map projected  non-map

IRB color
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Merged IRB
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Merged RGB
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RGB color
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Black and white
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IRB color
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Black and white
map-projected  (353MB)
non-map           (338MB)

IRB color
map projected  (145MB)
non-map           (265MB)

Merged IRB
map projected  (191MB)

Merged RGB
map-projected  (181MB)

RGB color
non map           (252MB)
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.