Nov. 14 (UPI) -- Researchers have found a massive crater left behind by an asteroid that struck Greenland some 12,000 years ago. The 19-mile-wide crater was discovered beneath a half-mile-thick slab of ice.
Scientists sussed out the contours of the crater using advanced radar technologies, including an ultra-wideband chirp radar system developed by researchers at the Center for the Remote Sensing of Ice Sheets at the University of Kansas.
The results of previous radar surveys, including NASA's Program for Arctic Regional Climate Assessment and Operation IceBridge, had hinted at the crater's presence beneath Hiawatha Glacier, located in northwest Greenland.
"We've collected lots of radar-sounding data over the last couple of decades, and glaciologists put these radar-sounding datasets together to produce maps of what Greenland is like underneath the ice," John Paden, associate professor of electrical engineering and computer science at Kansas, said in a news release.
Danish researchers first noticed the crater-like depression while studying the radar data collected by surveys conducted in 1997 and 2014.
"Based on this discovery, a detailed radar survey was conducted in May 2016 using a new state-of-the-art radar designed and built by Kansas University for the Alfred Wegener Institute in Germany," Paden said.
Researchers flew the new radar system, the Multichannel Coherent Radar Depth Sounder, over the remote glacier at low altitudes to get detailed data on the crater's dramatic dimensions.
"From the airplane it is subtle and hard to see unless you already know it's there," Paden said. "Using satellite imagery taken at a low sun angle that accentuates hills and valleys in the ice sheet's terrain -- you can really see the circle of the whole crater in these images."
To confirm the nature of the massive depression, scientists trekked to the base of the glacier to collect sediments deposited by the largest river draining the crater. Glass sediments analyzed in the lab revealed the presence of shocked quartz and other impact-related grains.
Researchers described their discovery this week in the journal Science Advances, but they are still working on precisely dating the impact. Scientists also want to better understand how the massive impact affected the climate, as well as the surrounding geography and ecosystems.
"There would have been debris projected into the atmosphere that would affect the climate and the potential for melting a lot of ice, so there could have been a sudden freshwater influx into the Nares Strait between Canada and Greenland that would have affected the ocean flow in that whole region," Paden said. "The evidence indicates that the impact probably happened after the Greenland Ice Sheet formed, but the research team is still working on the precise dating."