Icy Martian lake holds as much water as Lake Superior

New analysis conducted using the Mars Reconnaissance Orbiter’s Shallow Radar (SHARAD) instrument has revealed the existence of subsurface water ice roughly equal in volume as Lake Superior buried beneath cracked, pitted plains in the Red Planet’s mid-northern latitudes.

The discovery, made by a team led by Cassie Stuurman of the University of Texas Institute for Geophysics and published in a recent edition of Geophysical Research Letters, found the frozen water buried beneath a 3 to 33-foot thick layer of soil in the region known as Utopia Planitia.

Using data collected by SHARAD during more than 600 passes over the plains, Stuurman and her colleagues determined that the ice deposits range in thickness from around 260 feet to about 560 feet and had 50% to 85% water composition, as they were mixed with dust and other rocky particles, NASA’s Jet Propulsion Laboratory (JPL) in California said in a statement.

The deposit is located approximately halfway between the equator and the north pole, between 39 and 49 degrees latitude. While water ice cannot exist on the surface of Mars in this location due to the planet’s thin and dry atmosphere, the layer of soil that covers it keeps it from turning into water vapor, the study authors noted.

A resource for astronauts, and a possible hint at microbial life?

According to Stuurman, the deposit likely originated as snowfall that mixed with dust and other particles and accumulated into an ice sheet at a time in which the planet’s axis had more of a tilt than it does today. The newfound ice, she added, represents less than 1% of all known water ice on the Red Planet, but more than doubles the volume of ice sheets in the northern plains.

The discovery could be good news for astronauts, as ice deposits located near the surface are being considered as a possible resource for human travelers to Mars. As study co-author and UT professor Jack Holt explained, this particular deposit is “more accessible than most water ice on Mars, because it is at a relatively low latitude and it lies in a flat, smooth area where landing a spacecraft would be easier than at some of the other areas with buried ice.”

Currently, all of the water located beneath Utopia Planitia is frozen, as a melted layer of liquid H2O would have been detectable by the radar scans. However, the researchers emphasized that they cannot rule out that some of it would have melted during different climate conditions when the planet’s axis had a greater tilt. Does that mean that there may have been enough liquid water to support microbial life at some point in Mars history? “We just don’t know,” Holt said.

“It’s important to expand what we know about the distribution and quantity of Martian water,” added Leslie Tamppari, a Mars Reconnaissance Orbiter Deputy Project Scientist at JPL. “We know early Mars had enough liquid water on the surface for rivers and lakes. Where did it go?  Much of it left the planet from the top of the atmosphere. Other missions have been examining that process. But there’s also a large quantity that is now underground ice, and we want to keep learning more about that.”


Image credit: NASA/JPL-Caltech/Univ. of Arizona