Buried deep beneath Greenland’s ice, scientists have discovered what could potentially be a 22-mile-wide impact crater.
If that is the case, it would be the second discovery announced in the past few months.
Just 114 miles from the recently discovered crater beneath the Hiawatha Glacier, a NASA glaciologist saw signs of the possible crater in northwest Greenland by looking over satellite imagery and topographic maps of the area.
But how and when it formed exactly is still a mystery — but researches believe it may be over 80,000 years old.
“We’ve surveyed the Earth in many different ways, from land, air, and space – it’s exciting that discoveries like these are still possible,” said a glaciologist at NASA’s Goddard Space Flight Center, Joe MacGregor, who recently participated in the crater discovery announced in November 2018.
That particular crater – estimated to be 19 miles wide – sits underneath the Hiawatha Glacier – which is now the first ever impact crater to be found beneath Earth’s ice sheets.
It was previously believed that most evidence of ancient impacts would have been erased by erosion of the overlaying ice over many year but after the first discovery, the team suspected there may be others.
“I began asking myself ‘Is this another impact crater? Do the underlying data support that idea?'” MacGregor shared.
“Helping identify one large impact crater beneath the ice was already very exciting, but now it looked like there could be two of them.”
The reseracher then anayzed images from teh Moderate Resolution Imaging Spectroradiometer instruments on NASA’s Tera and Aqua satellites, along with those from NASA’s Operation IceBrdige — discovering what looked to be a bowl-shaped depression in the bedrock.
The suspected crater is estimated to be 22.7 miles wide.
The team says it would be the 22nd largest impact crater known to Earth — that is, if it really turns out to be one.
“The only other circular structure that might approach this size would be a collapsed volcanic caldera,” MacGregor shared.
“But the areas of known volcanic activity in Greenland are several hundred miles away. Also, a volcano should have a clear positive magnetic anomaly, and we don’t see that at all.”
Despite the new crater sitting only 114 miles away from the one announced in November, researchers believe they did not form at the same time.
The team says the ice in the area is at least 79,000 years old.
Researches say that if it really is an impact crater, it either happened over 79,000 years ago, or, if it was more recently, all of the ice from the time — eroded.
“The ice layers above this second crater are unambiguously older than those above Hiawatha, and the second crater is about twice as eroded,” MacGregor stated.
“If the two did form at the same time, then likely thicker ice above the second crater would have equilibrated with the crater much faster than for Hiawatha.”
The team also says it is possible that the two neighboring craters were formed by entirely separate impact events.
They say this is consistent with Earth’s cratering record.
“This does not rule out the possibility that the two new Greenland craters were made in a single event, such as the impact of a well separated binary asteroid, but we cannot make a case for it either,” said planetary scientist with the Southwest Research Institute in Boulder, Colorado, William Bottke.
“The existence of a third pair of unrelated craters is modestly surprising but we don’t consider it unlikely,” MacGregor stated.
“On the whole, the evidence we’ve assembled indicates that this new structure is very likely an impact crater, but presently it looks unlikely to be a twin with Hiawatha.”
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