Martian Ice Caps Reveal Insights into Ancient Climate Shifts

Martian Ice Caps Reveal Insights into Ancient Climate Shifts
by Agatha Bordonaro
Hanover, NH (SPX) Aug 30, 2024

Katherine Lutz, a PhD student at the Guarini School of Graduate and Advanced Studies and National Science Foundation Fellow, began her journey in planetary science by examining satellite images of Mars' polar ice caps. These images revealed spiraling patterns across the ice caps, which are composed of alternating layers of ice and dusty deposits and range between 400 to 1,000 meters deep. These spiral formations, unique to Mars, sparked her curiosity.

"These look amazing, but do we actually understand why they form or how they evolve over time?" Lutz asked. Her research in the lab of professor Marisa Palucis, who specializes in planetary landscape evolution, seeks to uncover the reasons behind these formations and their implications.

The layers of the Martian polar ice cap provide scientists with one of the most reliable climate records for Mars. "Mars has undergone massive climate change and we spend a lot of time as planetary scientists trying to understand that," Palucis explained. "The question of how much water has flowed across its surface (and when) has been central to its exploration."

Previous research in 2013 suggested that these "troughs" might result from katabatic winds - rapidly moving winds that cause erosion before slowing down and depositing material, leading to asymmetric trough walls and cloud formations corresponding with wind activity.

However, Lutz, Palucis, and Earth sciences professor Robert Hawley analyzed a decade's worth of new Mars images and data. They found that while 80% of the troughs were indeed asymmetric, about 20% were not. The troughs on the outer edges of the ice cap were found to form a fairly uniform "V" shape, with walls of similar height on either side, and not all troughs were associated with cloud cover.

In a paper published this year in the 'Journal of Geophysical Research: Planets', the researchers propose that these outer troughs are younger than those at the center of the polar ice cap and likely result from heavy erosion rather than a katabatic wind cycle. This suggests that 4 to 5 million years ago, a shift in the Martian climate may have altered the planet's water cycle, influencing the movement of winds, clouds, and ice.

This finding could explain the differences between the troughs at the center and those at the edges of the ice cap: they formed during different periods under varying climate conditions.

Such discoveries are critical in understanding whether Mars can support - or has ever supported - life. "If we ever want to have people on Mars, we need to figure out the history of this water source," Lutz said, referring to the ice layers in these spirals. "Could we potentially be using it to, say, extract drinkable water? And if we ever want to find evidence of life there now, we're not going to look at the outer edges of the ice cap, where it's just a lot of erosion and no water going into the system and there's not a lot of heating."

Lutz emphasized that these ice-cap layers represent records of the climate on modern Mars. Additional modeling is necessary to further understand the history and function of these spiral features, with the ultimate goal of deploying a rover to Mars to gather more concrete data about the troughs.