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LAWRENCE – A Greenland ice survey showed evidence suggesting that a kilometer of iron asteroid hit the island about 12,000 years ago at the end of Pleistocene. The resulting 30-kilometer crater remained hidden beneath a sheet of ice half a kilometer away. Recently, he underwent a research into ultra-wideband radar radar systems developed at CRSSIS, based at Kansas University.
The impact crater under Hiawatha glaciers in the northwest of Greenland is detailed in a new Science Advances article.
It was identified by data collected by the Canadian University for the NASA Arctic Regional Climate Assessment and Operation IceBridge program from 1997 to 2014 and supplemented by additional data collected in May 2016 using KU's Multichannel Coherent Radar Depth Sounder (MCoRDS).
"In recent decades we have acquired a lot of radar data and glaciologists have put together these radar data files to create Greenland maps under ice," said co-author John Paden, associate professor of electrical engineering and computer science at KSU and researcher at CReSIS. "The Danish scientists looked at the map and saw this great crater's depression under the ice sheet and looked at the satellite images and – because the crater is on the edge of the ice layer – you can see a circular pattern . " The combination of these two things strongly showed that it was a crater Based on this discovery, a detailed radar survey was conducted in May 2016, using the latest state-of-the-art radar designed and built by KU for the Alfred Wegener Institute in Germany. "
Paden, who contributed to the development of MCoRDS software for radar signal processing, participated in low height flights in the grille model above the impact crater to examine the dimensions in detail.
"You can see a rounded structure at the edge of the ice sheet, especially when you fly up," he said. "For the most part, the crater is not visible from the plane's window, and it's funny that no one ever thought" Hey, what is the semicircular outline there? "It's hard to see on the plane if you do not know it's there, when the sun is a little over the horizon, highlighting the hills and valleys in the ice layer – you can actually see the crater circle in these images.
To confirm the satellite and radar findings, the research team carried out further field studies of the glaciofluvial sediment in the largest river that drives the crater. This highlighted the presence of "the impact of quartz and other affected grains," which include glass. The research team believes that these glassy rocks and skins probably came from the collision with the melting of cereals in the sediment base rock.
It is however necessary to specify the moment of the fall of the asteroid in Greenland. The authors write that the evidence "suggests that the Hiawatha crater was created during the Pleistocene, because this age is largely consistent with the findings in the data currently available." However, this wide time interval remains "unsafe." In the crater from the southwest, he found a region rich in possible fragments created during the accident, which could help narrow down the date range.
"The atmosphere would have dirt that would affect the climate and have the potential to melt a lot of ice, so a flood of fresh water could come to the Nares Strait between Canada and Greenland, which would affect the flow of the oceans in the region," said Paden. "Evidence suggests that the impact could arise after the capacity of ice in Greenland was created, but the research team is still working on a precise meeting."
Credit: University of Kansas
Other members of the KU staff who participated in the research that revealed the impact of the crater include Rick Hale, president of air engineering and associate director of CReSIS; Carla Leuschena, professor of electrical engineering and computer science and director of CReSIS, and Fernando Rodriguez-Morales, professor of electrical engineering and computer science. KU researchers have worked closely with colleagues at the University of Copenhagen and the Alfred Wegener Institute in Germany.
Paden says that for three years between discovering the crater and publishing this discovery, it was a pleasure and interest to be part of an exclusive group of scientists who knew of a massive impact.
"It was very cool – it was the kind of thing I told my kids when I came home," Paden said. "I said," Look at this, it's under the ice. "This was one of the fun moments, they were amazed; my research is often not interesting for them, but this impact crater was something that caught them."
Source: today.ku.edu
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