The red planet has experienced six to 20 different ice ages over the past 300-800 million years, a new analysis of glaciers on Mars has revealed.
During the last ice age on Earth, 20,000 years ago, our planet was covered in glaciers. Then those glaciers retreated to the poles. These ice masses left the rocks as evidence, causing them to fall as they scraped and sculpted the paths as they made their way towards the posts.
Martian glaciers, on the other hand, have never been gone. They have been frozen on the planet’s surface, which has an average negative temperature of 81 degrees Fahrenheit, for more than 300 million years; They have just been covered in debris.
“All the rocks and sand contained in that ice remained on the surface,” study author Joe Levy, a planetary geologist and assistant professor of geology at Colgate University, said in a statement. “It’s like putting ice in a refrigerator under all that sediment.”
Glaciers on Mars have long been a mystery to geologists who have tried to determine whether there was an extended Martian ice age that caused their formation or whether they formed over multiple ice ages spanning millions of years.
Studying the rocks found on the surface of glaciers could answer this question. Levy determined that as rocks erode over time, the discovery of rocks that have moved from higher to lower downhill would suggest an ice age.
Since it is not yet possible to visit Mars and study its surface in person, Levy and 10 students at Colgate University in upstate New York used images of 45 glaciers taken by NASA’s Mars Reconnaissance Orbiter.
The high resolution images allowed the researchers to count the rocks and determine their size. Zooming in on the orbiter images allowed the team “to see things the size of a dining table” on the Martian surface, Levy said.
The researchers counted and measured a total of 60,000 rocks. The AI would have reduced some of the work, which took two summers to complete, but the AI cannot distinguish the rocks on the glacier’s surface.
“We did kind of virtual fieldwork, going up and down these glaciers and mapping the rocks,” Levy said.
Instead of a stable arrangement of rocks of different sizes, the researchers observed unexpected randomness.
“In fact, the rocks were telling us a different story,” Levy said. “It wasn’t their size that mattered, it was how they were grouped or grouped.”
The rocks were actually traveling inside the glaciers, rather than outside of them, so the rocks were not eroded.
But they were visible in the debris rings on the surface of the glaciers. These rings help mark different ice currents that formed during different ice ages.
Ice ages occur when the tilt of a planet’s axis changes, known as obliquity, so these different ice ages formed separately to reflect the times when Mars essentially spun on its axis.
This sheds light on the Martian climate and how it has changed.
“There are really 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 findings suggested that Mars experienced multiple ice ages.
“This document is the first geological evidence of what the orbit and obliquity of Mars could have done for hundreds of millions of years,” Levy said. “These glaciers are small time capsules, which capture snapshots of what was blowing in 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; We can only take a long walk the surface. “
The contents of these glaciers could include evidence of life that may have once existed on Mars.
“If there are biomarkers around, those too will get stuck in the ice,” Levy said.
The discovery of bands of rock within glaciers is also useful information for astronauts who will one day land on Mars and drill into glaciers to use their frozen water.
Researchers will continue to map glaciers on Mars in hopes of learning more about the planet’s past and whether life has ever existed in its history.
“There is a lot of work to be done to understand the details of the history of the Martian climate, including when and where it was warm and humid enough to be brine and liquid water,” Levy said.