An international team of researchers, including the NASA Glaciologist, has discovered a large crater impact meteorite hiding under a mile of ice in northwestern Greenland.
The crater – the first of any size below Greenland's ice sheet – is one of the 25 largest craters on Earth, measuring 1,000 feet and a diameter of more than 19 kilometers.
The group, led by researchers from the University of Copenhagen's Center for GeoGenetics at the Natural History Museum of Denmark, has worked for the last three years to verify their discovery, which they initially did in 2015 using NASA data, according to the November 14 issue of Science Advances.
"NASA is making the data it collects freely for scientists and the public around the world," says Gregor Gregor, a NASA geologist at the Goddard Space Flight Center, who took part in the investigation in the early stages. "It set the stage for our Danish colleagues" Eureka's Moment. "
The researchers first identified the crater in July 2015, while testing a new topography map below the Greenland ice sheet, which used ice-penetrating radar data mainly from the NASA's "Icebridge" mission – an airborne multi-year mission to track The Arctic ice changes – and earlier NASA missions in Greenland, and scientists noticed a huge, previously untested, round depression under the glacier of the Hiawatta, at the tip of the ice tip in northwestern Greenland.
Using satellite imagery from the sophisticated imaging apparatus of television and aqua, McGregor also examined the surface of ice in the Hiawatha glacier, and quickly found evidence of a circular pattern on the ice surface corresponding to that seen in the bed topography map.
To confirm their suspicions, in May 2016, the team sent a research plane from the German Alfred Wagner Institute to fly over the Hewawath Glacier and find the crater and the ice above it using state-of-the-art radar from the University of Kansas, McGregor, Ice, helped shape the airborne survey.
"Previous radar measurements of the Hayawata Glacier were part of NASA's long-term effort to map Greenland's changing ice cover," McGregor said. "What we really need to test our hypothesis was a dense radar survey focused there. The survey exceeded all expectations and simulated the depression in amazing details: a clear circular language, a central ascension, a disturbed and undisturbed ice layer, and basic waste – everything is there. "
The crater was formed less than 3 million years ago, according to the study, when an iron meteorite more than half a kilometer crushed into northwestern Greenland. The subsequent depression was covered by ice.
"The crater has been remarkably preserved, which is surprising because glacial ice is a very effective evasive agent that would quickly remove its traces," says Kurt Kier, a professor at the Center for Geogenetics at the Natural History Museum of Denmark and lead author of the study.
Kjær says the state of the crater indicates that the impact could also occur towards the end of the last ice age, which will place the crater formed among the youngest on Earth.
During the summer of 2016 and 2017, the research team returned to the glacier Hiawatha to map tectonic structures in the rock near the foot of the glacier and collect samples of precipitation washed away from the depression through a watercourse.
"Some of the quartz sand coming from the crater has platelet deformation features that indicate violent influence," said Professor Nikolai Larsen of Aarhus University in Denmark, a co-author of the study.
Previous studies have shown great effects can affect the climate of the Earth, with serious consequences for life on Earth at that time. The researchers intend to continue their work in this field, addressing the remaining questions about when and how the meteorite impact on the Hiawatha glacier influenced the planet.
Picture shown: The Hiawatha impact crater is covered by the Greenland ice sheet, which flows just beyond the rim of the crater, forming a semi-circular tip. Part of this end (top of the picture) and the rim of the ice breaking the rim of the crater are shown in a photograph taken during a flight of Operation Isbridge. Of NASA on April 17.
Credits: NASA / John Sontag