250 million years ago a meteorite hit Antarctica | Polarjournal
Glowing meteor entering the earth’s atmosphere

An international team of researchers has discovered a huge impact crater under the ice of Antarctica with the help of two GRACE satellites. This could be one of the largest meteorite craters on Earth. The structure, which is more than 450 kilometres in size, is hidden under an ice sheet about one and a half kilometres thick. Is the gigantic impact related to the largest mass extinction in Earth’s history?

Wilkesland Crater is the largest known meteorite crater on Earth. It has a diameter of about 480 kilometers and is probably 250 million years old. (Graphic: Heiner Kubny)

Was the giant meteorite whose impact crater was discovered in Antarctica the greatest killer of all time? Researchers have discovered a crater 1.5 kilometres beneath the Antarctic ice crust, 482 kilometres in diameter. It probably dates back to a meteorite impact 250 million years ago. The force of the impact at Wilkesland was catastrophic for Earth and its inhabitants at the time, according to scientists. At that time, almost all life on Earth was wiped out.

The meteorite crater was first discovered in Antarctica in 2006. A joint mission by NASA and the German Aerospace Center, which attempted to measure anomalies in Earth’s gravitational field to show how mass is distributed on the planet and how it changes over time, was responsible for the discovery.

New details from 2018 about the gravity field of East Antarctica, obtained by the GRACE satellites, revealed a prominent positive gravity anomaly in a basin about 500 kilometers in diameter.

Some scientists are sure that in the bowels of Antarctica, in the area of Wilkes Land, hides an M-class asteroid, composed mainly of metals.

The discovery also sparked fierce debate among conspiracy theorists, who quickly recalled claims that the Nazis had built secret facilities there during World War II.

The twin satellite Gravity Recovery and Climate Experiment (GRACE) is a project for the precise determination of the Earth’s gravitational field in low orbit. The satellites were launched on March 17, 2002 into a near-polar and circular orbit with an initial altitude of 500 km. They circle the earth at a distance of about 200 km and continuously measure the mutual distance with microwaves. (Photo: Airbus)

The massive impact is believed to have thrown huge amounts of dust into the air, making for a very hostile environment – months of darkness and caustic acid rain have made the planet hell. Only a few primeval shellfish survived this inferno. Among them were the ancestors of the dinosaurs, which became the dominant group of animals in the following nearly 200 million years. What sounds like a grim future scenario actually ended the Permian age about 250 million years ago. “An estimated 80 to 90 percent of marine and terrestrial life died back then,” says Michael J. Benton, professor of paleontology at the University of Bristol.

How this mass extinction occurred 250 million years ago is disputed among scientists. While some researchers suspect meteorite impacts, others assume volcanic eruptions. “Volcanic activity, accompanied by colossal CO2 emissions, is now considered by many scientists to have triggered the mass extinction,” Benton says.

This is what the Chicxulub crater on Mexico’s Yucatan Peninsula might have looked like after the meteorite impact 66 million years ago. The diameter of the crater is estimated at 180 kilometers. Today it lies buried more than a kilometre below the surface. (Graphic: Detlev van Ravenswaay)

The impact crater discovered in East Antarctica is about three times the size of the Chicxulub crater on the Yucatan Peninsula. A meteorite had fallen there about 65 million years ago, which may have been responsible for the extinction of the dinosaurs. But the meteorite that smashed the giant scar into the Antarctic crust was several times larger than the “dinosaur killer”, with an estimated diameter of more than 45 kilometres.

Heiner Kubny, PolarJournal

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