Scientists have discovered an ice sheet below the surface of Mars comparable in volume to the amount of water in Lake Superior.

In an examination of Mars’ Utopia Planitia region, scientists discovered  an ice deposit that ranges in thickness from about 260 feet (80 meters) to about 560 feet (170 meters). The deposit is composed of 50 to 85 percent water ice, mixed with dust or larger rocky particles.

“This deposit probably formed as snowfall accumulating into an ice sheet mixed with dust during a period in Mars history when the planet’s axis was more tilted than it is today,” said Cassie Stuurman of the Institute for Geophysics at the University of Texas, Austin. She is the lead author of a report in the journal Geophysical Research Letters.

Using the Mars orbiter’s ground-penetrating Shallow Radar (SHARAD) instrument, data (seen below) was able to indicate the presence of the ice sheet.

These two images show Shallow Radar (SHARAD) instrument data from two tracks in a part of Mars' Utopia Planitia region where the orbiting, ground-penetrating radar on NASA's Mars Reconnaissance Orbiter detected subsurface deposits rich in water ice. Credits: NASA/JPL-Caltech/Univ. of Rome/ASI/PSI

These two images show Shallow Radar (SHARAD) instrument data from two tracks in a part of Mars’ Utopia Planitia region where the orbiting, ground-penetrating radar on NASA’s Mars Reconnaissance Orbiter detected subsurface deposits rich in water ice.
Credits: NASA/JPL-Caltech/Univ. of Rome/ASI/PSI

It is believe that this ice sheet accumlated at an earlier period in Mars’ history where the planet’s axis was more tilted than it is today; currently, liquid water cannot exist on the surface of Mars, however it is possible that this ice sheet accumlated at an earlier period of time, when snowfall was entirely possible.

“This deposit probably formed as snowfall accumulating into an ice sheet mixed with dust during a period in Mars history when the planet’s axis was more tilted than it is today,” said Cassie Stuurman of the Institute for Geophysics at the University of Texas, Austin. She is the lead author of a report in the journal Geophysical Research Letters.

via: NASA