In even the smallest backyard telescope, you can see the prominent ice caps at both of Mars's poles. Although the planet was probably warm enough to have liquid water on its surface, all that remains are these thick ice sheets at its poles. Astronomers assumed that these caps were ancient, formed at some point in the last few billion years when Mars lost its water. But new evidence shows that the northern sheet is young, forming between 2 and 12 million years ago.

Mars's northern ice cap is young with a cold, stiff mantle beneath

To understand the properties of the rocky mantle beneath Earth's continents, researchers use a little geophysical trick: they measure how fast large areas of land, once covered by kilometres of ice during the last ice age around 20,000 years ago, continue to rise today.

(www.dlr.de)