Scientists analyzing radar images from NASA's Mars Reconnaissance Orbiter spacecraft have found as many as seven distinct layers of ice and dust beneath the north pole.
Roger J. Phillips, a scientist with the Southwest Research Institute in Boulder, Colo., said the layering was probably caused by changes in the planet's orbit over the last 4 million years.
When the planet tilts strongly on its axis, the surface ice erodes and is covered by a layer of dust, Phillips said.
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| This image provided by NASA is a small portion of an exposure taken in March 2008 by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Some high-latitude areas on Mars and Earth exhibit similarly patterned ground where shallow fracturing has drawn polygons on the surface. This patterning may result from cycles of freezing and thawing. |
