Carbon Dioxide Ice in the Late Summer
Carbon Dioxide Ice in the Late Summer
ESP_023464_0945  Science Theme: Climate Change
Mars has extremely large temperature changes from winter to summer compared to the Earth. It gets cold enough to freeze carbon dioxide out of the atmosphere during the winter, but this ice is unstable when the warmer summer arrives and forces it to sublimate (transform directly back into a gas) away.

Near the South Pole though, it stays cold enough for some of this seasonal ice to stick around all year and even accumulate from year to year. This image shows a portion of this permanent carbon dioxide ice cap. This slab of ice is a few meters (about 10 feet) thick and is penetrated by the flat-floored pits shown here. The quasi-circular pits in the center of the scene are about 60 meters (200 feet) across.

The distinct color of the pit walls may be due to dust mixed into the ice. For most of the year these walls are covered with bright frost, but they defrost and show their true colors at the end of the summer.

Written by: Shane Byrne  (7 September 2011)
Acquisition date
29 July 2011

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
245.2 km (152.4 miles)

Original image scale range
49.1 cm/pixel (with 2 x 2 binning) so objects ~147 cm across are resolved

Map projected scale
50 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
78°, with the Sun about 12° above the horizon

Solar longitude
336.2°, Northern Winter

For non-map projected images
North azimuth:  125°
Sub-solar azimuth:  57.1°
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Black & white is 5 km across; enhanced color about 1 km
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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.