The Red Planet has survived between six and 20 separate ice ages over the past 300 to 800 million years, a new analysis of Mars’ glaciers has revealed.
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 masses of ice left rocks behind as evidence, dropping them as they scraped and carved paths as they moved toward the poles.
Martian glaciers, on the other hand, have never left. They remain frozen on the surface of the planet, which has an average temperature of negative 81 degrees Fahrenheit, for more than 300 million years – they have just been covered with debris.
“All the rocks and sand transferred to this ice have remained on the surface,”
The glaciers of Mars have long been a mystery to geologists who have tried to determine whether there was an extended Martian ice age that caused them to form, or whether they formed over multiple ice ages spanning millions of years.
The study of rocks found on the surface of glaciers could answer this question. Levy determined that because rocks erode over time, the discovery of rocks that shift from larger to smaller in size would suggest an ice age.
Given that it is not yet possible to visit Mars and study its surface in person, Levy and 10 students at Colgate University in New York have used images of 45 glaciers taken by a NASA intelligence orbiter.
The high resolution of the images allows researchers to count the scales and determine their size. Enlarging images in orbit allows the team to “see things the size of a dinner table” on the Martian surface, Levy said.
The researchers counted and measured a total of 60,000 scales. Artificial intelligence would reduce some of the work that took two summers, but AI could not distinguish the rocks from the surface of the glacier.
“We did some kind of virtual fieldwork, we went up and down these glaciers and we mapped the rocks,” Levy said.
Instead of a stable arrangement of rocks of different sizes, the researchers observed an unexpected coincidence.
“Actually, the stones told us a different story,” Levy said. “It didn’t matter their size; it was the way they were grouped or grouped.”
The rocks actually traveled inside the glaciers, not on the outside, so the rocks didn’t erode.
But they could be seen in ring debris on the surface of the glaciers. These rings help to mark different flows of ice formed during different ice ages.
Ice ages are caused when the tilt of the planet’s axis shifts, known as tilt, so these individual ice ages form separately to reflect the times when Mars was essentially swaying on its axis.
This sheds some light on the Martian climate and how it has changed.
“There are really good models for the orbital parameters of Mars over the last 20 million years,” Levy said. “Then the models tend to get chaotic.”
The team’s findings suggest that Mars has experienced many ice ages.
“This document is the first geological evidence of what the Martian orbit and tilt could do hundreds of millions of years ago,” Levy said. “These glaciers are small time capsules that take snapshots of what’s blowing in the atmosphere of Mars. 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 just take march on the surface. “
The contents of these glaciers may include evidence of life that once existed on Mars.
“If any biomarkers blow around, they will also be trapped in the ice,” Levy said.
The discovery of rock strips in glaciers is also useful information for astronauts who may one day land on Mars and break into glaciers to use its water ice.
Researchers will continue to map the glaciers of Mars in hopes of learning more about the planet’s past and whether life ever existed in its history.
“A lot of work needs to be done to understand the details of Mars’ climate history, including when and where it was warm and humid enough to have brine and liquid water,” Levy said.