Radar profile through Mars's north polar ice shield
Radar profile through Mars's north polar ice shield
This image shows a cross-section of Mars's north polar cap, derived from data acquired by the Mars Reconnaissance Orbiter's Shallow Radar (SHARAD), one of six instruments on the spacecraft. The data reveals the internal structure of the polar cap, with the transition from ice to the rocky crust marked by a dashed line. In some areas, the ice is three kilometres thick. Researchers have discovered that the crust show’s a surprising lack of depression (see how the dashed line is nearly perfectly flat), suggesting that the polar cap is young and the crust has not had enough time to substantially subside. The bending rate of the crust is estimated to be a maximum of 0.13 millimetres per year – a low speed that indicates the rocky mantle of Mars, deep under the polar cap, has a very high viscosity.
