Mars has frozen water beneath its dust cover, say Niels Bohr researchers

Researchers at the Niels Bohr Institute in Copenhagen, Denmark, say Mars has huge glaciers of frozen water covered with thick layer of dust that appears as surface of the ground.

The belts of frozen water that researchers located at its central latitudes in both the southern and northern hemispheres are in addition to the distinct polar ice caps of Mars.

The study was carried out using satellite images and radar observations combined with ice flow modelling. Researchers have now calculated the size of the glaciers and the amount of water in the glaciers to be the equivalent of all of Mars being covered by more than one meter of ice.

Several satellites orbit Mars and using satellite images researchers have been able to observe the shape of glaciers just below the surface.

For a long time scientists did not know if the ice was made of frozen water (H2O) or of carbon dioxide (CO2) or whether it was mud.

The Niels Bohr researchers used radar measurements from the NASA satellite, Mars Reconnaissance Orbiter, to determine that is water ice.

The results are published in the scientific journal, Geophysical Research Letter.

''We have looked at radar measurements spanning ten years back in time to see how thick the ice is and how it behaves. A glacier is after all a big chunk of ice and it flows and gets a form that tells us something about how soft it is. We then compared this with how glaciers on Earth behave and from that we have been able to make models for the ice flow,'' says Nanna Bjørnholt Karlsson, a post-doctoral researcher at the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.

Karlsson explains that earlier studies have identified thousands of glacier-like formations on the planet. The glaciers are located in belts around Mars between the latitudes 300-500 - equivalent to just south of Denmark's location on Earth. The glaiciers are found on both the northern and southern hemispheres.

From some locations on Mars they have good detailed high-resolution data, while they only have more sparse data from other areas. But by supplementing the sparse data with information about the flow and form of the glaciers from the very well studied areas, they have been able to calculate how thick and voluminous the ice is across the glacier belts.

''We have calculated that the ice in the glaciers is equivalent to over 150 billion cubic meters of ice - that much ice could cover the entire surface of Mars with 1.1 meters of ice. The ice at the mid-latitudes is therefore an important part of Mars' water reservoir,'' explains Karlsson.

That the ice has not evaporated out into space could actually mean that the thick layer of dust is protecting the ice. The atmospheric pressure on Mars is so low that water ice simply evaporates and becomes water vapour. But the glaciers are well protected under the thick layer of dust.