Mars is dead and barren now, but billions of years ago the Red Planet used to have a thick atmosphere that supported a warm and wet environment. Today, we can still see evidence of the planet’s wetter past in the form of channels and ridges that used to flow with rivers and oceans. Over time, the atmosphere got thinner and, spurred by the weaker gravity, most of Mars’ water evaporated and escaped into space.
That’s not to say, however, that Mars is completely devoid of water. Last year, NASA made a landmark announcement after its researchers found evidence of flowing salty water on the planet’s surface. The lion’s share of water on Mars, though, is trapped within the ice caps at the north and south poles of the planet. The caps are an average of 2 miles (3 kilometers) thick and, if completely melted, could cover the Martian surface with about 18 feet (5.6 meters) of water.
If we humans ever want to settle Mars, the first outpost will likely have to be located near a vast water deposit. One possible drop zone could be someplace in Mars’ Utopia Planitia (‘plains of paradise’) region where NASA scientists found a new ice stockpile. The frozen ice buried beneath a couple of meters of Martian soil was found by Mars Reconnaissance Orbiter’s Shallow Radar (SHARAD) which made 600 overhead passes.
“It’s important to expand what we know about the distribution and quantity of Martian water,” said Mars Reconnaissance Orbiter Deputy Project Scientist Leslie Tamppari of NASA’s Jet Propulsion Laboratory in Pasadena, California. “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.”
The team estimates the layer of ice is 79-171 meters (260-560 ft) thick and likely carries as much water as Lake Superior, the largest of the Great Lakes in the US. The spectrographic analysis revealed the ice is made of 85 percent water, while the rest is a mix of dust and other solids.
“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 University of Texas Institute for Geophysics, the lead author of a report in the journal Geophysical Research Letters.
The Utopia Planitia ice deposit is one of the most appealing for exploitation on Mars. It spans latitudes from 39 to 49 degrees within the plains and holds twice as much volume of water than other thick, buried ice sheets known in the northern plains.
“This deposit is probably 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,” said Jack Holt, a research professor at the University of Texas Institute for Geophysics.
“The ice deposits in Utopia Planitia aren’t just an exploration resource. They’re also one of the most accessible climate change records on Mars,” said Joe Levy of the University of Texas Institute for Geophysics, a co-author of the new study. “We don’t understand fully why ice has built up in some areas of the Martian surface and not in others. Sampling and using this ice with a future mission could help keep astronauts alive, while also helping them unlock the secrets of Martian ice ages.”