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The remains of a glacier have been found near the equator of Mars, suggesting that some form of water could still exist in an area on the red planet where humans may one day land.
The ice mass no longer exists, but scientists have spotted telltale remnants among other mineral deposits near the equatorial region of Mars. The deposits there usually contain light-colored sulfates.
When scientists took a closer look, they recognized the features of a glacier, including ridges called moraines—debris deposited or pushed by a moving glacier. The research team also spotted fissure fields, or deep wedge-shaped openings that form within glaciers.
The findings were shared Wednesday at the 54th Lunar and Planetary Science Conference in The Woodlands, Texas.
“What we found is not ice, but a salt deposit with the detailed morphological features of a glacier,” said lead study author Dr. Pascal Lee, senior planetary scientist at the SETI Institute and the Mars Institute, in a statement.
“What we think happened here is that the salt formed on top of a glacier while preserving the shape of the ice below, down to details like the fissure fields and moraine bands.”
Researchers believe the glacier was 3.7 miles (6 km) long and 2.5 miles (about 4 km) wide, with an elevation of 0.8 to 1.1 miles (1.3 to 1.7 km).
Scientists have an idea of how the glacier footprint came about, based on evidence of volcanic material in the area. 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 the glacier ice, chemical reactions would have taken place at the boundary between the two to form a hardened layer of sulfates,” said study co-author Sourabh Shubham, a PhD student in geology. in university. of Maryland, College Park, in a statement.
“This is the most likely explanation for the hydrated and hydroxylated sulfates we observe in this light-colored deposit.”
The volcanic material likely eroded over time, revealing the salty layer that captured an imprint of the glacier’s ice and features, said study co-author John Schutt, a geologist at the Mars Institute and a guide to Arctic and Antarctic ice fields. .
Mars has a thin atmosphere, which allows space rocks to regularly collide with the planet’s surface. But the fine, detailed features of the glacier 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 Amazonian Martian geologic period, which began 2.9 billion years ago and is still ongoing.
“We know of glacial activity on Mars in many locations, including the equator in the more distant past. And we’ve known about recent glacial activity on Mars, but so far, only at higher latitudes,” Lee said. “A relatively young glacier at this location tells us that Mars experienced surface ice recently, even near the equator, which is young.”
Researchers don’t know if ice remains beneath the deposit.
“Water ice is not, at present, 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 is possible that all of the glacier’s water ice has sublimated by now. But there is also a possibility that some of them are still protected at a shallow depth under the sulfates.”
During the study, the team also looked at ancient ice islands called salars in the Bolivian Altiplano salt flats in South America. Blankets of salt have protected old glacial ice from melting or evaporating, leading researchers to believe that a similar scenario may have occurred on Mars.
Next, the researchers want to determine if there is ice left from the glacier, and if so, how much exists at shallow depths below the salt deposits. If this particular salt deposit is protecting the ice, it is likely that there are other pockets of ice nearby.
Orbiters orbiting the planet have shown ice deposits at the cold poles of Mars, but if water exists in any form at the warmer equatorial lower latitudes, it could have implications for our understanding of the red planet’s history and possible habitability. – and future human exploration.
“The desire to land humans in a location where they could extract water ice from the ground prompted mission planners to consider higher latitude sites,” Lee said. “But the latter environments are typically colder and more difficult 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 worlds: warmer conditions for human exploration and still access to the ice.”