A newly discovered crater in the Antarctic Ice may be the result of a meteorite impact. Craters are common, but if confirmed this could be by far the most recent large meteorite crater and a reminder of how little we know about the frozen continent.
Geoscientist Dr. Christian Müller of Fielax was conducting an aerial survey of the King Baudouin Ice Shelf on December 20 of last year when she spotted the crater. “About 5 or 6 kilometres away from the aircraft, I saw a massive circular structure about 2 kilometres across,” Müller said. Where there would normally be a flat ice shelf, there was broken ice that looked like icebergs.
The crater is small compared to the Chicxulub Crater associated with the end of the dinosaurs (180km) or the record-holding 300km Vredefort Crater, but these craters are tens or thousands of millions of years old.
Even Arizona's much smaller and better preserved Barringer Crater is around 50,000 years old. Müller's discovery makes those look positively ancient. It is likely to have been formed during the lifetime of people alive today, perhaps 25 years ago.
The discovery was a lucky find. Researchers at Belgium's Princess Elisabeth Research Station were planning to survey the continental bedrock further south. “We’d had some problems with the radar equipment and had taken it out of the Polar 6 aircraft for repairs. So in order to not waste a good flying day, we chose to fly the part of our planned survey that crosses the King Baudouin Ice Shelf,” said Dr. Graeme Eagles, a scientist at Germany's Alfred Wegener Institute.
Ice will not retain a deformity for long, so whatever caused the crater must be recent, at least on geological timescales. In 2004, a meteor blast occurred nearby, and Müller originally thought this may have created the shape he saw. However, satellite images indicate that the crater dates back at least to 1996.
Geologists use the rule of thumb that craters are generally 10-20 times larger than the objects that made them, which would require the initiator to be at least 100 meters across. "A very large explosion would have caused a 2-kilometer-wide crater — much larger than anything detected impacting Earth in recent history," Professor Peter Brown of the University of Western Ontario told Live Science. "So the feature seen is almost certainly not due to any meteorite impact."
However, the Wegener Institute are not ready to abandon the theory just yet, particularly in the absence of a convincing alternative explanation. They returned to the site on Boxing Day to map the ice surface with laser-scanning instruments and radar. Complicating the question, they also found several smaller circular structures nearby. The Wegener Institute is keen to search for meteorite fragments, but “we have to finish the survey we came out here to do,” Eagles said. “This circular structure will have to go on the back burner until then.”