Underground Ice on Mars Exposed by Impact Cratering

The High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter took these images of a fresh, 6-meter-wide (20-foot-wide) crater on Mars on Oct. 18, 2008, (left) and on Jan. 14, 2009. Each image is 35 meters (115 feet) across. This crater's depth is estimated to be 1.33 meters (4.4 feet).

Images (not shown here) taken by the Thermal Emission Imaging System camera on NASA's Mars Odyssey orbiter and by the Context Camera on the Mars Reconnaissance Orbiter show that the impact that excavated this crater occurred sometime between Dec. 22, 2008 and July 5, 2008.

The impact exposed water ice from below the surface. It is the bright material visible in this pair of images. The change in appearance from the earlier image to the later one resulted from some of the ice sublimating away during the Martian northern-hemisphere summer, leaving behind dust that had been intermixed with the ice. The thickening layer of dust on top obscured the remaining ice. This crater is at 43.28 degrees north latitude, 164.22 degrees east longitude.

These images are subframes of full-frame images that are available online at at http://hirise.lpl.arizona.edu/PSP_010440_2235 and http://hirise.lpl.arizona.edu/ESP_011574_2235.