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Dusty snow unearthed by NASA’s Phoenix Mars Lander, inches below the surface. The blue box represents ice and the red box represents the ground. Credit: NASA / JPL-Caltech / University of Arizona / Texas A&M University.
Over the past two decades, scientists have found ice in many places on Mars. Most of the Martian ice has been observed from orbital satellites like NASA’s Mars Reconnaissance Orbiter. But determining the grain size and dust content of the ice from this distance above the surface is a challenge. And these aspects of ice are crucial in helping scientists determine the age of ice and how it settled.
So, planetologists Aditya Khuller and Philip Christensen of Arizona State University, along with Stephen Warren, a land ice and snow expert at the University of Washington, developed a new approach to determine how much ice in March is really dusty.
By combining data from NASA’s Phoenix Mars Lander and NASA’s Mars Reconnaissance Orbiter with computer simulations used to predict the brightness of snow and glaciers on Earth, they were able to match the brightness of Martian ice and determine its dust content. Their results were recently published in AGU’s 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 might see on Earth. The dustier the ice, the darker and therefore hotter the ice becomes, which can affect both its stability and its evolution over time. Under certain conditions, it could also mean that ice could melt on Mars.
Illustration of how small amounts of Martian dust can reduce the brightness and change the color of Martian snow. The colored lines in the graph (blue, red, yellow, and purple) correspond to how small amounts of dust reduce the brightness of pure snow (represented by a black line) to the brightness of pure Martian dust (represented by a gray line). The simulated “color” of each type of snow / dust is shown in the black boxes. Notice how the color of snow with 0.1% dust looks very similar to the color of pure dust, as also seen on the Curiosity rover after a dust storm (right) Credit: NASA / JPL-Caltech / MSSS.
“There’s a chance that dusty, dark ice will melt a few inches away,” Khuller said. “And any underground liquid water produced by the melt will be protected from evaporation in the vaporous atmosphere of Mars by the overlying ice cover.”
Based on their simulations, they predict that the ice carved by Phoenix Mars Lander has formed by dusty snowfall, over the past million years, similar to other ice deposits previously found at mid-latitudes. Of March.
Ice unearthed by NASA’s Phoenix Mars Lander, a few inches below the surface. The red and blue boxes indicate the locations of the brightness measurements shown on the right. Blue represents ice and red represents ground. Credit: NASA / JPL-Caltech / University of Arizona / Texas A&M University. The ice and soil measurements by Blaney et al. (2009).
“It is widely believed that Mars has experienced several ice ages in its history, and it appears that the ice exposed to the mid-latitudes of Mars is a remnant of that ancient dusty snowfall,” Khuller said.
For the next steps, the team hopes to deepen the analysis of ice exposure on Mars, assess whether the ice might actually melt, and learn more about the climate history of Mars.
As the snow grains grow larger and larger, the amount of air between the grains decreases and the ice appears darker. This reduces the number of light reflections in the ice and increases the likelihood that the light will be absorbed by the ice. As the squalls grow larger, the brightness decreases and older snow, névé and glacier ice appear darker than fresh, clean snow. The figure on the right illustrates how the air contained in the snow gradually shrinks to form snowfield and eventually glacial ice. Credit: Mattavelli (2016).
“We are working on developing improved computer simulations of Martian ice to study how it changes over time and whether it might melt to form liquid water,” Khuller said. “The results of this study will be an integral part of our work, because knowing how dark the ice is directly influences the heat it makes.”
Melting dusty ice may have carved Martian ravines
Aditya R. Khuller et al, Spectral Albedo of Dusty Martian H 2 O Snow and Ice, Journal of Geophysical Research: Planets (2021). DOI: 10.1029 / 2021JE006910
Provided by Arizona State University
Quote: Martian snow is dusty, could potentially melt, according to a new study (2021, August 23) retrieved on August 23, 2021 from https://phys.org/news/2021-08-martian-dusty-potentially.html
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