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The Red Planet has experienced between six and 20 distinct ice ages over the past 300 to 800 million years, a new analysis of glaciers on Mars has found.
During the last ice age on Earth 20,000 years ago, our planet was covered with glaciers. These glaciers then retreated to the poles. These ice masses left rocks behind as evidence, dropping them scraping and carving paths as they moved toward the poles.
The Martian glaciers, on the other hand, never left. They have remained frozen on the surface of the planet, which has an average temperature of less than 81 degrees Fahrenheit, for more than 300 million years – they have just been covered with debris.
“All of the rocks and sand carried on this ice stayed on the surface,” study author Joe Levy, planetary geologist and assistant professor of geology at Colgate University, said in a statement. “It’s like putting ice in a cooler under all that sediment.”
The glaciers of Mars have long posed a mystery to geologists who have attempted to determine whether there was a prolonged Martian ice age that caused their formation or whether they formed over several ice ages spanning millions. years.
The study of rocks found on the surface of glaciers could answer this question. Levy determined that since rocks erode over time, finding rocks that have gone from larger to smaller on the way down would suggest an Ice Age.
Since it is not yet possible to visit Mars and study its surface in person, Levy and 10 students from Colgate University in New York State used images of 45 glaciers taken by NASA’s Mars Reconnaissance Orbiter.
The high resolution of the images allowed researchers to count rocks and determine their size. The magnification of the orbiter’s images allowed the team to “see things the size of a table” on the Martian surface, Levy said.
The researchers counted and measured 60,000 rocks in total. Artificial intelligence reportedly reduced some of the work, which took two summers, but AI cannot distinguish rocks on the glacier’s surface.
“We did a kind of virtual field work, going up and down these glaciers and mapping the rocks,” Levy said.
Rather than a regular arrangement of rocks of different sizes, the researchers observed an unexpected randomness.
“The rocks actually told us a different story,” Levy said. “It wasn’t their size that mattered; it was how they were grouped or grouped together.”
The rocks were actually traveling inside the glaciers, rather than outside, so the rocks didn’t erode.
But they were visible in rings of debris on the surface of glaciers. These rings help mark distinct flows of ice that have formed during different ice ages.
Ice ages are caused when the tilt of a planet’s axis shifts, called obliquity, so these distinct ice ages formed separately to reflect times when Mars essentially wobbled on its axis.
This sheds some light on the Martian climate and how it has changed.
“There are some very good models for the orbital parameters of Mars for the last 20 million years,” Levy said. “After that, the models tend to get chaotic.”
The team’s results suggest that Mars experienced several ice ages.
“This article is the first geological evidence of what the Martian orbit and obliquity could have done for hundreds of millions of years,” Levy said. “These glaciers are small time capsules, capturing snapshots of what blew through the Martian atmosphere. We now know that we have access to hundreds of millions of years of Martian history without having to dig deep into the crust. hike along the surface. “
The contents of these glaciers could include evidence of life that may have existed on Mars.
“If there are biomarkers blowing, those will be trapped in the ice as well,” Levy said.
The discovery of rock bands inside glaciers is also useful information for astronauts who may one day land on Mars and pierce glaciers to use its water ice.
Researchers will continue to map glaciers on Mars in hopes of learning more about the planet’s past and whether life ever existed in its history.
“There is a lot of work to be done to find the details of the history of the Martian climate, including when and where it was hot enough and humid enough that there was brines and liquid water,” said said Levy.
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