Subsurface analysis has led to the discovery of a huge reserve of frozen water under the North Pole of the red planet.
The amount of ice trapped between layers of underground sand is such that if it were to melt it could submerge the entire planet!
"It was a big surprise for us too," explains Stephen Nerozzi, from the University of Austin, Texas, lead author of the discovery.
A “lasagna” of sand and ice
The ice reserve has been located within several layers of mixed water to sand formed over the course of millions of years, and goes more than two kilometers below the surface of the planet: it is more than double that assumed in a study carried out in the past weeks and not yet widespread on a large scale.
The study was published in the journal Geophysical Research Letters and it is fruit of analyses made by SHARAD, the depth radar supplied to the Mars Reconnaissance Orbiter.
The volume of water compared to that of sand varies from 61% to 88%: it is as if the entire surface of Mars could be covered by a small sea one and a half meters deep: it is a gigantic quantity.
Near the Martian North Pole, the layers of water extend for up to 40 kilometers, and alternate with “thin” layers of sand ranging from 50 to 100 meters deep: they are the fruit of different periods that have seen the global temperature of the planet rise or fall, and therefore will also be a excellent system of recording how (and when) the Martian climate changed in the last million years.

The discovery now changes the entire perception of the planet in relation to its water availability: It is probable that this it is also found at several other latitudes and it is really, really a lot.
Good news for the "settlers" of the coming years, therefore, if not it was because of the difficulty to reach some of these underground "deposits", especially those beyond the two kilometers depth.