Thursday , July 29 2021

NASA detects a massive crater under Greenland ice



NASA makes endless discovery under Greenland ice

Two views on the Hiawatha crater region: one covered by Greenland ice sheet, the other shows the topography of the mountain under the ice, including the crater. Credits: NASA / Cindy Starr

An international research team, including a glaciologist from NASA, has discovered a major meteorite war crash hiding under more than half a mile of ice in northwestern Greenland. The crater – the first of any size found under Greenland's ice – is one of the 25 largest craters on earth, measuring about 1,000 feet deep and more than 19 miles in diameter, an area slightly larger than that found in the Washington Capital Beltway .

The group, led by researchers from the Copenhagen Center for GeoGenetics at the Danish Museum of Natural History, has been working for the last three years to verify their discovery, which they originally did in 2015 using NASA data. Their results are found in the November 14 issue of Science Advances.


An international team of researchers came together to tear up the mystery of Greenland's Hiawatha crater. This video shows how the discovery came together. Credits: NASA / Jefferson Beck

"NASA makes data that it collects freely available to researchers and the public worldwide," said Joe MacGregor, a NASA glaciologist at the Goddard Space Flight Center in Greenbelt, Maryland, who was involved in the investigation at his early stages. "It set the scene for our Danish colleague's" Eureka "moment."

The researchers first discovered the crater in July 2015, while inspecting a new map of the topography under Greenland's ice that used intrinsic radar data, mainly from NASA's Operation IceBridge – a multi-year airborne mission to track changes in the police – and former NASA flight missions in Greenland. The scientists noticed a huge, previously unexamined circular depression under the Hiawatha glacier, which is located at the edge of the ice in northwestern Greenland.

Using satellite images from the instrument of moderate resolution imaging spectral radiometers on NASA's Terra and Aqua satellites, MacGregor also examined the ice surface in the Hiawatha glacier area and quickly found evidence of a circular pattern on the ice surface that matched the one observed in the bed topography map.

To confirm their suspicions, in May 2016, the team sent a research plan from the German Alfred Wegener Institute to fly over the Hiawatha glacier and chart the crater and the overlying ice with a state-of-the-art ice-penetrating radar from the University of Kansas. MacGregor, an expert on radar measurements of ice, helped to design the airborne survey.

Unexpected discovery under Greenland ice

Radar data from an intensive aerial survey of the Hiawatha crater in May 2016 are shown here in watercolor curtains. A blue arrow points to the center of the crater. Credits: NASA / Cindy Starr

"Previously radar measurements of the Hiawatha glacier were part of a long-term NASA effort to map Greenland's ice-exchange," MacGregor said. "What we really needed to test our hypothesis was a tight and focused radar survey there. The survey exceeded all expectations and depicted depression in amazing detail: a clear circular edge, central elevation, disturbed and undisturbed ice storage and basalt debris – that's all there. "

The crater was formed less than 3 million years ago, according to the study, when an iron meteorite broke more than half a mile in northwestern Greenland. The resulting depression was then covered by ice.

"The crater is exceptionally well-preserved and it is surprising that ice ice is an incredibly effective erosive means that would soon have eliminated traces of effect," says Kurt Kjær, professor at the Center for GeoGenetics at the Danish Museum of Natural History and lead the author of the study.

Kjær said that the condition of the crater indicates that the support might have occurred towards the end of the last ice age, which would place the resulting crater among the youngest on the planet.

During the summer of 2016 and 2017, the research group returned to the Hiawatha glacier to map tectonic structures in the mountain near the glacier's foot and collect samples of sediment washed out of depression through a meltwater channel.

"Some quarries from the crater had planar deformation characteristics that indicate violent consequences. This is crucial evidence that the depression under the Hiawatha glacier is a meteorite crater," says Professor Nicolaj Larsen at Aarhus University in Denmark, one of the authors of the study.

Earlier studies have shown great consequences can greatly affect the climate of the earth, with major consequences for life on earth at that time. The researchers plan to continue their work in this area, address remaining questions about when and how the impact of the meteorites on the Hiawatha glacier affected the planet.

Publication: Kurt H. Kjær, et al., "A major battlefield under the Hiawatha glacier in northwestern Greenland," Science Advances, Nov. 14, 2018: Vol. 4, no. 11, eaar8173; DOI: 10.1126 / sciadv.aar8173


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