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Buried Martian glaciers could cover the planet in water

Elizabeth Howell, News Writer
Apr 9, 2015, 22:03 UTC

Sen—Mars has enough water in buried glaciers to cover the entire planet in water one metre deep, a new study reveals.

While the glaciers themselves have been known for some time—NASA's Mars Reconnaissance Orbiter (MRO) found evidence in 2008—the new study uses a decade of radar observations from the spacecraft to better understand their composition and extent.

The glaciers are one of the few places on Mars where water can exist. It is believed that the thick layer of dust on top of the ice prevents them from evaporating into the atmosphere, as exposed water on the surface would. Ice also exists at the north and south poles of Mars, and perhaps mixed in with the dust as well in certain latitudes.

"The glaciers probably represent a time (more than 5 million years ago) when the water ice that is now on the poles was deposited at the mid-latitudes. Later the water migrated back to the poles (because the climate changed), and the glaciers are remnants of this ice-cover and were 'left behind' so to speak," Nanna Bjørnholt Karlsson, a postdoctoral researcher at the Niels Bohr Institute at the University of Copenhagen, told Sen in an email.

"The next step would be to include more data in the analysis, and to investigate other areas of the planet," Karlsson added.

Most of the glaciers are found on Mars at northern or southern mid-latitudes similar to where Denmark lies on Earth. High-resolution data only exists for a portion of these locations, but combined with modelling, the researchers were able to come up with a figure of 150 billion cubic metres of ice.

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Hellas Crater, where a glacier likely deposited sediment (as seen in the troughs and ridges). Image credit: NASA/JPL-Caltech/Univ. of Arizona

Mars, once considered a planet bereft of water, is now known as a location where the liquid was abundant in the past. NASA's three rovers (Spirit, Opportunity and Curiosity) all located rocks on the surface that formed in the presence of water, such as hematite. Similar minerals have also been spotted from orbit.

Additionally, observations with spacecraft such as MRO and ESA's Mars Express have revealed extensive networks of gullies with similar characteristics created by water on Earth. Curiosity's observations have found evidence of an ancient lake bed and other surface formations likely created by water, as well.

What is puzzling scientists is where all the water went. A new NASA spacecraft called MAVEN (Mars Atmosphere and Volatile Evolution) is examining the rate at which the atmosphere thins, which could help explain how the water left the surface. Answering this question will better narrow down how hospitable Mars is or was to microbes.

The new research was published in Geophysical Research Letters.