Researchers develop a new method for analyzing rock glaciers

Standing on a rock glacier is what Tyler Meng imagines it could be like to face on the floor of Mars. The glacier’s barren and wrinkled panorama seems to be like Foolish Putty that is drooped below gravity’s pull, providing few clues {that a} frozen, debris-laden large lurks beneath the floor.

Rock glaciers are so named as a result of in contrast to pure ice glaciers, they’re a mixture of frozen water, sand and rocks. They’re typically discovered on the base of steep mountainsides or cliffs which have slowly dropped rock particles, which then mixes with glacier ice and refrozen snowmelt. Rock glaciers additionally exist on Mars.

Meng—who’s pursuing a doctoral degree in planetary science on the College of Arizona, with a minor in geosciences—is lead writer of a research within the Journal of Glaciology that describes a brand new methodology to find out rock glaciers’ ice thickness and the ratio of ice to mess, permitting for extra exact measurements of those glaciers than beforehand attainable. Meng and his adviser and co-author Jack Holt, a UArizona planetary sciences and geosciences professor, used this data to create maps of 4 rock glaciers in Colorado, Wyoming and Alaska.

Their work, and future work that makes use of this methodology, will enable scientists to higher perceive water sources on each Earth and Mars, in addition to how resilient one of these buried ice might be to the altering local weather on each planets.

Greater than ice

Rock glaciers are hidden and insulated by particles on prime of ice, and their motion is affected by the rocks trapped inside them.

“You may consider the rocks like an insulating blanket,” Meng mentioned. “Past a sure thickness, insulation principally turns off the melting, permitting for the ice to be preserved and slowly transfer or move down a valley at elevations and temperatures the place clear ice could also be utterly melted.”

Each pure ice glaciers and rock glaciers can transfer throughout landscapes—very slowly. Nevertheless, the particles in rock glaciers causes them to move much more slowly than ice glaciers, because the inclusion of rocks makes them a lot stiffer. They’re additionally usually smaller and thinner than clear ice glaciers, measuring only a couple miles in size, a number of hundred or thousand ft huge and between 50 and 200 ft thick. Ice glaciers, in distinction, may be many miles in size and 1000’s of ft thick.

To gather the knowledge wanted to map and characterize these hidden giants, Meng, Holt, different UArizona college students and their collaborators hiked rugged mountain terrain within the western U.S., lugging computer systems, battery packs and radar antennas on their backs. They navigated steep landscapes with free rocks ranging in measurement from grains of sand to homes.

“Standing on a debris-covered glacier is fairly surreal, as a result of it is on this barren space on a mountainside, and every rock glacier appears to have its personal character,” Meng mentioned. “They every have a barely completely different kind of bedrock supplying particles, and the valley geometry dictates its form and look.”

Utilizing two completely different antenna configurations, the researchers used ground-penetrating radar to measure each the radar wave pace and the angle at which the wave was mirrored from the subsurface. In the identical approach that people have two eyes to see in three dimensions, two antenna configurations allowed the researchers to higher calculate the size of the rock glacier. Additionally they estimated the ratio of ice to rock at every survey location utilizing radar wave velocity.

“Within the course of, we made essentially the most exact estimates of rock glacier geometry and composition up to now,” Meng mentioned.

From Earth to Mars

Understanding rock glaciers on Earth is essential as a result of they’re primarily water reservoirs, Meng mentioned.

“Our analysis provides us a greater thought of the total water finances in mountainous areas, the place main rivers have headwaters,” he mentioned. “Snow is a year-to-year accumulation that covers a complete panorama, whereas rock glaciers are a extra localized however everlasting water reservoir that truly shops water for what may very well be a whole lot to a couple thousand years.”

The researchers are persevering with their evaluation to grasp indicators of previous local weather change in rock glaciers and the way these glaciers may need advanced by previous local weather modifications.

“By having a map of the particles thickness and ice focus, we will primarily characterize the flexibility of rock glaciers to face up to results of a warming local weather in comparison with clear ice glaciers,” Meng mentioned.

Different scientists additionally acknowledged rock glaciers on Mars by their wrinkled putty-like move sample, even earlier than radar knowledge detected them.

Martian rock glaciers are nonetheless not nicely understood, Meng mentioned, however it’s recognized that they’re usually discovered between 30 and 60 levels latitude in each of the planet’s hemispheres and are a lot older than the Martian polar ice.

“These Martian rock glaciers are potential targets for water sources on Mars, too, as a result of they’re really actually massive in comparison with those on Earth, like a whole lot of meters thick,” Meng mentioned. “They’re additionally extra accessible than polar ice as a result of spacecraft would not have to vary their orbits as a lot as they’d in the event that they have been to land on a pole, which requires much more gas to succeed in.”

One of many massive challenges for scientists is figuring out the thickness of the floor rock masking the glaciers on Mars. If there may be 30 ft of rock and particles on rugged Martian terrain, then it won’t be definitely worth the hassle for astronauts to try to entry the ice for water resources, Meng mentioned.

“Our aim is to make use of these rock glaciers on Earth as an analog for processes on Mars,” Meng mentioned. “By mapping the patterns of particles thickness on Earth, we’re attempting to grasp how that particles thickness can also differ on Mars. Additionally, by studying in regards to the variations in move parameters between clear ice and debris-rich ice, that can assist simulations for the Martian case as nicely.”

Shifting ahead, Holt’s analysis group is constant to make comparable measurements utilizing surface-based radar whereas amassing new knowledge utilizing drones. This drone-based knowledge assortment will assist the group to realize a extra full understanding of rock glacier move and subsurface traits, whereas additionally testing new geophysical strategies which may be utilized in future exploration of Earth and Mars.