Research by geologists in Alaska leads to Mars
Jeffrey Trop, left, and Craig Kochel.
Posted May 14, 2008; updated July 17, 2008
Astrobiology Magazine highlights research
In 2006, while Kochel and Trop were in Alaska studying icy debris fans, the result of falling snow, ice and sediment being eroded from upper-level ice-caps, the two geologists started work on a paper published online this month in the journal Icarus suggesting that the terrain of Alaska might help scientists better understand what's happening on Mars.
This spring, the High Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter sent back to Earth images showing geologic conditions not only similar to what the two Bucknell scientists had observed in Alaska's Wrangell Mountains, but a surprise as well.
The Mars orbiter's camera snapped what is described as the first-ever images of an active Martian avalanche.
The series of four photographs show tan clouds billowing away from the foot of a towering slope down which ice and dust had just cascaded. The dramatic images saw national press and scientific community interest and were featured on the Mars Reconnaissance Orbiter Web site. || More avalanche images from the High Resolution Imaging Science Experiment
"We asked NASA to consider targeting the HiRISE camera along the large steep escarpments of the Northern Polar Layered Terrain, particularly along the large canyon called Chasm Boreale," said Kochel. "Our thought was that fan-shaped deposits seen in earlier photographs might be similar to what we saw in the icy debris fans in
Trop explained that the polar region of Mars is similar to
"This sets up a situation where gravity can act along fractures in the ice to allow pieces to waste off the upper part of the escarpment and cascade to the base as avalanches," he said.
The Bucknell scientists ended an October 2007 Geological Society of America "Wet Mars" presentation by predicting that NASA would find similar avalanche deposits on the northern polar escarpments of Mars.
"Jeff and I saw this and we now have the good fortune of having our predictions realized," said Kochel. "But no one ever expected them to actually photograph the avalanches in action. But they caught four of them. It's truly amazing."
"The significance of avalanches on Mars is that this is a major active mass-wasting process driven by gravity," said Kochel. "This is a major discovery."
In the new research paper, "Earth Analog for High-Latitude Landforms and Recent Flows on Mars: Icy Debris Fans in the Wrangell Volcanic Field, Alaska," expected to published this year in Icarus, the International Journal of Solar System Studies, Kochel and Trop suggest that Alaska experience could help to explain the current geological process on Mars. (The online manuscript is here.)
Kochel and Trop said one implication is that these avalanches may be moving water in the form of ice from the Red Planet's high elevations to lower elevations. "This may be a mechanism to provide volumes of snow and ice necessary to contribute to glacier formation and movement without having to invoke significant precipitation," said Trop.
Their new paper also discusses what appears to be a never-before described geomorphic feature -- a "hybrid fan-glacier." That's when avalanches of snow and ice are so plentiful that the icy debris fan has begun to flow as a glacier.
"It has become a glacier because the thickness of ice has reached the point where it begins to deform, or flow, under its own weight," said Kochel. "It's actually a glacier on top of a glacier."
Cameras orbiting Mars have taken thousands of images, but NASA said "it is extremely rare to catch such a dramatic event in action" and that the avalanche photographs present a "very rare opportunity" for scientific study.
It is not known precisely what triggered the Mars avalanches.
NASA postulates it could be caused by the disappearance of the carbon dioxide frost, the expansion and contraction of the ice in response to temperature differences, a nearby Mars-quake or meteorite impact, and vibrations caused by the first fall in the area.
Clouds of material
NASA said the recently released images show material, likely including fine-grained ice and dust and possibly including large blocks, having become detached from a towering cliff and cascaded to the slopes below. The avalanches are "spectacularly revealed" by the accompanying clouds of fine material that continue to settle out of the air.
NASA said by imaging this scarp throughout the polar summer, scientists may be able to determine how much material falls over a given time period.
"These observations would help determine how much, and at what rate, ice is being eroded from the cliff. Understanding the processes and rates of erosion will help determine how the polar landscape has evolved, and help reveal how volatiles, such as water and carbon dioxide ices and gases, move around Mars," NASA said.
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