A group of researchers from TU Delft and the Institute for Planetary Research of the German Aerospace Center have been able to the determinate the Mars’s interior structure and the age of the large ice sheet covering its north pole. They have published their findings in Nature. The team used the same geophysical trick on Mars that geologists use here on Earth to: measure how large areas of land are deformed by the ice sheet that presses down on the planet itself. That in turn says a lot about the material and structure underneath all that ice.