Drone radar reveals buried glaciers on Earth, guiding the search for water on Mars
by Kylianne Chadwick, University of Arizona
Understanding how to explore hidden glaciers on Mars begins not in a laboratory, but in remote field camps across Alaska and Wyoming.
Armed with mosquito repellent, bear spray and drone batteries charged by a generator the night before, a team of researchers at the University of Arizona spent long days driving off-road, hiking rugged terrain and launching drones.
In a study published in the Journal of Geophysical Research: Planets, the team demonstrated that ground-penetrating radar mounted on drones can map the thickness of rocky debris covering glaciers on Earth. These results could help future astronauts locate accessible water locked in buried ice on the Red Planet.
"If you want to make decisions about where to drill on Mars, you need to know if the ice you're trying to find is under one meter of debris or 10," said Roberto Aguilar, a doctoral researcher at the University of Arizona Lunar and Planetary Laboratory and first author of the paper. "That's the kind of information a drone-based system could provide."
How debris-covered glaciers differ
Most people picture glaciers as massive blocks of exposed ice, dusted with bright white, powdery snow. Debris-covered glaciers, however, appear very different, with their icy core hidden by thick layers of rock and sediment. These glaciers are found in mountainous regions on Earth, including warmer areas such as Colorado and California, where debris helps insulate and keep the ice underneath from melting.
On Mars, debris-covered glaciers are found in mid-latitude regions, halfway between the equator and the polar caps. According to Aguilar, some Martian ice deposits occur in craters that have been filled with ice and later covered by dust. Others form in large valleys where ice accumulated and was subsequently buried by debris. In mountainous regions, rockfall can also act as a protective layer, shielding the underlying ice from escaping into the atmosphere.
"Some of these deposits are large enough that radars on orbiting spacecraft can detect and estimate the amount of ice, but current technology cannot determine fine details, such as how thick the overlying debris layer is, or if there are internal, rocky layers hidden from view," Aguilar said.
Testing drone radar on Earth
According to Aguilar, buried ice could be one of Mars' most valuable resources. Water ice on Mars could preserve a record of past environmental conditions, support future astronauts through drinking water supplies, oxygen production and agriculture, and help guide drilling for astrobiology research.
To get there, however, the team first needed to test the approach on Earth.
What the radar revealed inside
The team compared measurements obtained with radar to those from excavating and drilling into the glaciers. The measurements of debris thickness matched, validating their method as reliable and effective.
Because drones can fly much closer to the surface than orbiting spacecraft, they can image the ground at much higher resolution. This allowed the researchers to not only estimate debris thickness but also assess the purity of the ice and spot any rocky layers hidden inside.
"The internal layers we're seeing are important because they're a record of past climate cycles," Aguilar said. "Each layer represents a different period of ice accumulation and environmental conditions over centuries or millennia, and it is likely we would see similar layers on Mars."
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