Researchers are celebrating after discovering a massive meteorite impact crater beneath more than half a mile of ice in Greenland. NASA and an international team of geologists found the first impact crater in Greenland, measuring over 1,000 feet deep and more than 19 miles in diameter.
The discovery took over three years to verify its existence. The University of Copenhagen's Centre for GeoGenetics at the National History Museum of Denmark used NASA data to confirm the findings.
Digging through the data
For decades, NASA has made data from its space programs and global monitoring programs available to everyone interested. Thus, researchers can explore whatever interests them.
"NASA makes the data it collects freely available to scientists and the public all around the world,” said Joe MacGregor, a NASA glaciologist at Goddard Space Flight Center in Greenbelt, Maryland, who became involved in the investigation in its early stages. “That set the stage for our Danish colleagues’ ‘Eureka’ moment."
The Danish team first found the crater in 2015 during an inspection of a topographical map of Greenland's ice sheet. They used NASA's Operation IceBridge data as well as earlier NASA missions to Greenland. That's when the scientists noticed something interesting. There was an unexplored depression under the Hiawatha Glacier in the northwest part of Greenland.
The team then used satellite images from NASA's Terra and Aqua satellites. MacGregor also found evidence of a circular pattern on the ice surface that matched the topographical map.
The researchers waited a full year to confirm their suspicions. They sent a research plane to fly over the glacier and map what they believed to be a crater with an ice-penetrating radar developed by the University of Kansas.
"Previous radar measurements of Hiawatha Glacier were part of a long-term NASA effort to map Greenland’s changing ice cover," MacGregor said. "What we really needed to test our hypothesis was a dense and focused radar survey there. The survey exceeded all expectations and imaged the depression in stunning detail: a distinctly circular rim, central uplift, disturbed and undisturbed ice layering, and basal debris — it’s all there."
Curious about the crater
The impact crater made geologists' lists of the 25 largest impact craters ever discovered on Earth.
According to data estimates, the crater was formed more than 3 million years ago. The impact from an iron meteorite over a half a mile wide crashed into northwest Greenland, the study reported. The depression was quickly covered by ice.
"The crater is exceptionally well-preserved and that is surprising because glacier ice is an incredibly efficient erosive agent that would have quickly removed traces of the impact," said Kurt Kjær, a professor at the Center for GeoGenetics at the Natural History Museum of Denmark and lead author of the study.
The team spent the next two summers -- 2016 and 2017 -- going back to the Hiawatha Glacier to track the tectonic structures. They also did research of the samples being washed out from the glacier.
"Some of the quartz sand coming from the crater had planar deformation features indicative of a violent impact; this is conclusive evidence that the depression beneath the Hiawatha Glacier is a meteorite crater," said associate professor Nicolaj Larsen of Aarhus University in Denmark, one of the authors of the study.
The discovery helps geologists build a better picture of what early Earth looked like. It can also now be a point of interest for climatologists. By tracking the changes of the crater, they can get a better understanding of how its impact shaped any life on Earth at the time.