Planetary geology
Martian pole boasts icy detail

A new map of Mars’ south pole revealed that the ice cap is composed almost entirely of water ice and measures up to 3.7 kilometers thick (thick regions are depicted in red and thin regions in blue). The circle represents the region where data were not collected. Image is courtesy of NASA/JPL/ASI/ESA/Univ. of Rome/MOLA Science Team/USGS.

Melt away all of the ice locked within the frozen ice cap of Mars’ south pole, and the entire planet would be awash in water 11 meters deep. The calculation comes from precise new maps of the planet’s south pole obtained using a radar instrument aboard the European Space Agency’s (ESA) Mars Express spacecraft.

Previous measurements by other spacecraft, such as NASA’s Mars Global Surveyor, have estimated the volume of Mars’ polar ice caps, but “never with the level of confidence this radar makes possible,” said Jeffrey Plaut of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in an ESA news release.

By measuring the amount of time that elapsed between radar signals reflected from the ice surface and from the planet surface, researchers could determine the ice’s thickness across the cap. Publishing March 16 in Science, Plaut and colleagues report that the thickest regions of the cap measure 3.7 kilometers deep.

The radar also turned up surprising features on the planet below the ice: Multiple depressions ranging from 50 to 200 kilometers wide and 1 kilometer deep could be from the weight of the ice or from craters left behind from impacts prior to the ice cap’s formation.

Kathryn Hansen

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