Standing on a rocky glacier, Tyler Meng imagines what it would be like to stand on the surface of Mars. The barren, wrinkled landscape of the glacier resembles the Stupid Putty sinking under the force of gravity, offering few clues that a frozen, rubble-filled giant lurks below the surface. Rock glaciers are so named because, unlike pure glaciers, they are a mixture of frozen water, sand and rock. They are usually found at the base of steep mountain slopes or cliffs where pieces of rock slowly fall and then mix with glacial ice and frozen melted snow. There are also rock glaciers on Mars.
Meng, who holds a PhD in planetary science from the University of Arizona with a specialization in earth sciences, is the lead author of the study. Journal of Glaciologydescribes a new method for determining rock glacier ice thickness and ice-to-debris ratio, providing more accurate measurements of these glaciers than previously possible. Meng and his advisor and co-author Jack Holt, professor of planetary and earth sciences at the University of Arizona, used this information to create maps of four rock glaciers in Colorado, Wyoming, and Alaska. Their work and future work using this method will allow scientists to better understand the water resources on both Earth and Mars, and how resilient this type of buried ice will be to climate change on both planets.
more than ice
Rock glaciers are hidden and isolated by debris from the top of the ice, and their movement is affected by the trapped rocks.
“You can think of rocks as an insulating blanket,” Meng said. “Above a certain thickness, the insulation basically stops melting, allowing the ice to continue and slowly move or flow down the valley at heights and temperatures where pure ice can melt completely.”
Both pure glaciers and rock glaciers can move very slowly between landscapes. However, rock glacier remnants cause them to flow more slowly than ice glaciers because the rock inclusions make them much harder. They are also generally smaller and thinner than pure ice glaciers, only a few miles long, a few hundred or thousands feet wide, and 50 to 200 feet thick. In contrast, ice glaciers can be kilometers long and thousands of feet thick.
Meng, Holt, other University of Arizona students and collaborators take a hike through the rugged mountainous terrain of the western United States, taking with them computers, batteries, and radar antennae to gather the information needed to map and characterize these hidden giants. ridges. With loose stones the size of grains of sand, they crossed cliffs and reached the houses.
“Standing on a glacier covered in debris is pretty surreal because it’s a barren area on the mountainside, and each rock glacier seems to have its own personality,” Meng said. “Each has a slightly different type of bedrock that feeds the debris, and the geometry of the valley determines its shape and appearance.”
Using two different antenna configurations, the researchers used ground-penetrating radar to measure both the speed of the radar wave and the angle of the wave rebound from the ground. Just as humans need two eyes to see a three-dimensional image, the two antenna configurations allowed the researchers to better calculate the size of the rock glacier. They also estimated the ice-rock ratio in each study area using radar wave velocities.
“During this process, we made the most accurate predictions ever of rock glacier geometry and composition,” Meng said. Said.
Earth to Mars
Understanding rock glaciers on Earth is important because they are essentially reservoirs of water, Meng said.
“Our study gives us a better idea of the overall water balance in mountainous regions where major rivers have their sources,” he said. “Snow is an accumulation that covers the entire landscape each year, whereas rock glaciers are a more local but permanent reservoir of water that stores water for hundreds or thousands of years.”
The researchers continue their analysis to understand the signatures of past climate change in rock glaciers and how these glaciers may have evolved due to past climate changes.
“By having a map of debris thickness and ice concentration, we can essentially characterize the ability of rock glaciers to withstand the effects of climate warming compared to pure glaciers,” Meng said. Said.
Other scientists have also recognized rock glaciers on Mars from crumpled paste-like flow patterns before they were detected by radar data. Martian rock glaciers are still not fully understood, but they are typically found between 30 and 60 degrees latitude in both hemispheres of the planet and are known to be much older than Martian polar ice, Meng said.
“These Martian rock glaciers are potential targets for water supplies on Mars because they’re actually so large compared to Earth’s, they’re hundreds of meters thick,” Meng said. Said. “They’re also more accessible than polar ice because they don’t have to change the orbits of the spacecraft as if they were going to land on the mast, which requires a lot more fuel to reach.”
One of the biggest problems for scientists is determining the thickness of the surface rocks that cover the glaciers on Mars. If the rugged terrain of Mars has 30 feet of rock and debris, perhaps astronauts shouldn’t be trying to access the ice for water, Meng said.
“Our goal is to use these rock glaciers on Earth to simulate processes on Mars,” Meng said. “By viewing patterns of debris thickness on Earth, we are trying to understand how debris thickness may also vary on Mars. Learning about the differences in flow parameters between clean ice and debris-rich ice will also aid modeling for the Martian state.”
Going forward, Holt’s research team continues to make similar measurements using ground-based radar while collecting new data using drones. This drone data collection will help the team gain a more complete understanding of glacial flow and subsurface rock features, as well as test new geophysical techniques that could be used in future exploration of Earth and Mars.
Source: Port Altele
