Latest Mars Avalanche Likely Triggered by Impact Event

By Nancy Atkinson - May 10, 2010 02:29 PM UTC | Planetary Science

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The HiRISE team from the Mars Reconnaissance Orbiter has captured a few avalanches on Mars,

some actually while in progress.

But this latest landslide is a little different. Above is a dust

avalanche

that created a streak on the slopes of Olympus Mons, the solar system's largest volcano. While scientists believe some of the previous

avalanches

seen on Mars occur due to the expansion and contraction of ice from seasonal temperature differences, this one was caused by an impact event. This HiRISE image was taken on March 31, 2010 and reveals a small, pristine impact crater (blue arrow). "It shows a fuzzy source area, which resembles the airblast patterns seen at many other recent impact sites," said Alfred McEwen, Principal Investigator for HiRISE. "The crater is only about 4.5 meters across, meaning the bolide was only about a half a meter wide, so it didn't take much to trigger this landslide."

[caption id="attachment_64187" align="aligncenter" width="580" caption="CTX images from Nov. 18, 2007 and Feb. 14, 2010. Credit: NASA/JPL/University of Arizona"]

[/caption] MRO's Context Camera (CTX) took an image of this area on Nov. 18, 2007 (left) and the adjacent image on Feb. 14, 2010, which shows a large new avalanche. HiRISE then took the follow-up image in March. McEwen said slope streaks , or dust avalanches are common on Mars, but this one is unusually wide and began from an unusual extended or "fuzzy" source area. This made HiRISE team conclude that an impact event occurred sometime between the dates of the CTX images and triggered the large dust avalanche.

"Sometimes, these dust avalanches are easily triggered," McEwen told Universe Today. "We've seen them caused just by dust devils. The dark area was created by an atmospheric blast associated with the impact event, with the bolide coming in at about 10 km per second that distributes the dust. You can see that the upper most fresh dust on the surface is bright, so this landslide disturbed either bare substrate or compacted, older dust.

[caption id="attachment_64181" align="aligncenter" width="448" caption="Color image of the impact-triggered dust avalanche. Credit: NASA/JPL/University of Arizona"]

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Planetary scientists say that landslides or avalanches on Mars can also be caused by small Mars-quakes or the sublimation of carbon dioxide frost which dislodges rocks.

Sources:

HiRISE

, phone conversation with Alfred McEwen.

Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com