NASA Finds Second Impact Crater Under Greenland Ice Sheet

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Greenland’s ice sheet is the second largest body of ice in the world, so scientists are naturally interested in how it’s changing with the climate and what’s under there. Recent studies of the ice sheet with radar revealed something unexpected: an impact crater. What’s more unexpected than an impact crater? A second impact crater. NASA says it just spotted a second crater just over a hundred miles from the first one, and the team believes they formed at different times.

In November of 2018, NASA announced the discovery of an impact crater under the Hiawatha glacier. This discovery came thanks to NASA’s Operation IceBridge, a project employing a fleet of aircraft to conduct radar scans of glaciers. The Hiawatha crater clocks in at 19 miles (31 kilometers) in diameter, and was most likely created by an iron meteorite strike. After finding this unexpected crater, scientists started looking for more evidence of ancient impacts under the ice.

The latest radar scans of Greenland appear to show a second crater, slightly larger than the first at 22 miles (36.5 kilometers) across. It has the characteristic flat bowl depression, along with an elevated rim and centrally located peaks. Operation IceBridge measurements also detected a negative gravity anomaly in the area, a common sign of impact craters. This is only the second impact crater discovered under ice, but it will be the 22nd largest in the world if confirmed via additional measurements.

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The two features are only 114 miles apart (the new crater is more inland than the Hiawatha crater). At first, the team wondered if the two craters came from the same impact event. For example, a binary paid of asteroids falling into Earth’s atmosphere. However, researchers have mostly discarded that idea. The new crater is far more eroded than the Hiawatha crater, and the morphology is shallower. So, the team currently believes they were formed at different points in Earth’s history.

The best current estimate dates the new crater around 2.6 million years old, much older than the Hiawatha crater at roughly 100,000 years. The new crater doesn’t have a name yet, but once its existence is confirmed, the team recommends Paterson crater. The name would honor glaciologist Stan Paterson who reconstructed climate data from the last 100,000 years from Greenland ice cores. 

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