Most of the Martian ice has been observed from orbiting satellites such as NASA's Mars Reconnaissance Orbiter. But determining the size and dustiness of ice so far from the surface is difficult. And these aspects of ice are critical in helping scientists determine how old ice is and how it formed.
So planetary scientists Aditya Huller and Philip Christensen of Arizona State University, along with Stephen Warren, an Earth ice and snow expert at the University of Washington, developed a new approach to determine how dusty Martian ice really is.
By combining data from NASA's Phoenix Mars Lander and Mars Reconnaissance Orbiter spacecraft with computer simulations used to predict the brightness of snow and glacial ice on Earth, they were able to successfully match the brightness of Martian ice and determine its dustiness. Their findings were recently published in the AGU Journal of Geophysical Research: Planets.
Mars is a dusty planet, so much of its ice is also dusty and much darker than the fresh snow we can see on Earth. The more dusty the ice, the darker and therefore warmer it becomes, which can affect both its stability and evolution over time. Under certain conditions, this could also mean that ice on Mars could melt.
“There is a chance the dusty and dark ice could melt a few centimeters,” Huller said. "And any subsurface liquid water produced by melting will be protected from evaporation in the thin Mars atmosphere by a layer of ice that covers it."
Based on their simulations, they predict that the ice dug up by the Phoenix Mars Lander spacecraft has formed from dusty snowfall sometime over the past million years, like other ice deposits previously discovered in the mid-latitudes of Mars.
“It is widely believed that Mars has experienced several ice ages throughout its history, and the ice exposed in the mid-latitudes of Mars appears to be a remnant of this ancient dusty snowfall,” Huller said.
As the next steps, the team hopes to continue analyzing the effects of ice on Mars, assess whether the ice may indeed melt, and learn more about the history of Mars' climate.
“We are working on improved computer simulations of Martian ice to study how it develops over time and whether it could melt to form liquid water,” Huller said. "The results of this study will be integral to our work, because knowing how dark ice is directly affects how much it heats up."