Northern Plains Seasonal Frost at Phoenix Landing Site
Northern Plains Seasonal Frost at Phoenix Landing Site
PSP_007207_2485  Science Theme: Glacial/Periglacial Processes
This image shows seasonal frost in the northern hemisphere plains of Mars, showing a portion of the landing ellipse for the Mars Scout spacecraft Phoenix. Phoenix will land somewhere within the ellipse on 25 May 2008 (Memorial Day in the United States.)

The bright surfaces in this image are covered with seasonal carbon dioxide frost (dry ice snow). During the winter, the entire surface was covered with a blanket of carbon dioxide frost about a foot deep. Now the frost is slowly sublimating away (changing directly from ice to gas) revealing small hexagonal and polygonal patterns a few meters (yards) in size in the darker soil beneath the surface.

The polygonal patterns on the surface are commonly referred to as “patterned ground” and are often found in high latitude and high alpine environments on Earth. The patterns are the result of annual thermal contraction in ice-cemented soil or permafrost that forms a honeycomb network of small fractures below the surface. This network of fractures is eventually manifested as small shallow troughs at the surface forming the hexagonal and polygonal patterns visible in this image. Bright carbon dioxide frost still fills the shallow troughs accentuating these patterns.

Written by: Maria Banks  (3 March 2008)
Acquisition date
09 February 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
312.1 km (194.0 miles)

Original image scale range
31.2 cm/pixel (with 1 x 1 binning) so objects ~94 cm across are resolved

Map projected scale
25 cm/pixel

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Emission angle

Phase angle

Solar incidence angle
60°, with the Sun about 30° above the horizon

Solar longitude
29.3°, Northern Spring

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North azimuth:  99°
Sub-solar azimuth:  316.8°
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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’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.