(CNN) The remains of a glacier have been found near the equator of Mars, suggesting that some form of water may still exist in an area of the Red Planet where humans may one day land.
The ice mass is no longer there, but scientists have spotted telltale remnants among other mineral deposits near Mars’ equatorial region. The deposits that usually contain bright sulfate salts.
When scientists looked closer, they recognized the features of a glacier, including ridges called moraines—debris deposited or pushed by a moving glacier. The research team also discovered fissure fields, or deep wedge-shaped openings that form inside glaciers.
The findings were shared Wednesday at the 54th Lunar and Planetary Science Conference in The Woodlands, Texas.
“What we have found is not ice, but a salt deposit with the detailed morphological features of a glacier,” said lead author of the study Dr. Pascal Lee, a senior planetary scientist at the SETI Institute and the Mars Institute, in a statement.
“What we think happened here is that salt formed on top of a glacier while preserving the shape of the ice below, down to details like fissure fields and moraine bands.”
The researchers believe the glacier was 3.7 miles (6 kilometers) long and 2.5 miles (about 4 kilometers) wide, with a height between 0.8 to 1.1 miles (1.3 to 1.7 kilometers) .
Volcanic activity creates a protective layer
Scientists have an idea of how the imprint of the glacier came to be, based on evidence of volcanic material in the region. When mixtures of volcanic ash, lava and volcanic glass called pumice react with water, a hard, crusty layer of salt can form.
“This region of Mars has a history of volcanic activity. And where some of the volcanic material came into contact with glacial ice, chemical reactions would have occurred at the boundary between the two to form a hardened layer of sulfate salts,” says study co-author Sourabh Shubham, a doctoral student in geology at the University of Maryland, College Park, said in a statement.
“This is the most likely explanation for the hydrated and hydroxylated sulfates we observe in this bright deposit.”
Geologically young surface ice near the equator
The volcanic material likely eroded over time, revealing the salty layer that captured an imprint of the glacial ice and its distinctive features, said study co-author John Schutt, a geologist at the Mars Institute and an Arctic and Antarctic ice field guide.
Mars has a thin atmosphere that allows space rocks to regularly collide with the planet’s surface. But the fine, detailed features of the glacier still remain largely undisturbed in the salt deposit, leading researchers to believe it is relatively “young”.
The study’s authors said they believe the glacier existed during the Martian Amazon geological period, which began 2.9 billion years ago and is still ongoing.
“We’ve known of glacial activity on Mars in many places, including near the equator in the more distant past. And we’ve known of recent glacial activity on Mars, but so far only at higher latitudes,” Lee said. “A relatively young relict glacier at this site tells us that Mars has experienced surface ice in recent times, even near the equator, which is new.”
The researchers do not know if there is ice left during the deposition.
“Water ice is not currently stable on the very surface of Mars near the equator at these altitudes,” Lee said. “So it’s not surprising that we don’t detect water ice at the surface. It’s possible that all of the glacier’s water ice has sublimated away now. But there’s also a chance that some of it is still protected at shallow depth beneath the sulfate salts.”
Potential for shallow ice pockets
During the study, the team also looked at ancient ice islands called salars in Bolivia’s Altiplano salt flats in South America. Blankets of salts have protected ancient glacial ice from melting or evaporating, leading scientists to believe that a similar scenario could have occurred on Mars.
Next, the researchers want to determine if there is ice left from the glacier, and if so, how much is present at shallow depths beneath the salt deposits. If this particular salt deposit protects ice, it is possible that other pockets of ice exist nearby.
Orbiters circling the planet have shown deposits of ice at the cold Martian poles, but if water exists in any form in the warmer equatorial lower latitudes, it could have implications for our understanding of the Red Planet’s history and potential habitability—and future human exploration.
“The desire to land humans in a place where they might be able to extract water ice from the ground has pushed mission planners to consider locations at higher latitudes,” Lee said. “However, the latter environments are typically colder and more challenging for humans and robots. If there were equatorial locations where ice could be found at shallow depth, then we would have the best of both environments: warmer conditions for human exploration and still access to ice. “