ASTER Science Team.
Meteorite impacts have shaped the development of the Earth and life repeatedly in the past. The extinction of the dinosaurs, for instance, is thought to have been brought on by a mega-collision at the end of the Cretaceous period. But how many traces of large and small impacts have survived the test of time?
The probability of a meteorite impact on Earth is not fundamentally different than on Mars. However, the Earth’s surface changes much more quickly. As a result, the craters remain visible for a much shorter period of time, meaning that many less of them are detectable today. “The main challenge of the study was to estimate the long-term effect of erosion, which causes craters to disappear over time,” says Hergarten.
“A surprising, initially sobering finding we made was that there are not many craters of above six kilometers in diameter left to discover on the Earth’s surface,” reports Hergarten. In the case of smaller craters, on the other hand, the scientists found the current list to be far from complete: Around 90 craters with a diameter of one to six kilometers and a further 250 with a diameter of 250 to 1000 meters are still awaiting discovery. While there are undoubtedly still a number undiscovered large craters buried deep under sediments, they are much more difficult to detect and confirm.
Goat Paddock Crater, located on the Kimberley Plateau of northwestern Australia, appears to straddle the simple-complex category, according to a study published in 2005.
Freiburg students have been involved in the research since 2011: The course “Screening Earth – a Student (Re)search Project” is held each year for master’s students in Geology. The course enables aspiring young geologists to participate in the search for undiscovered craters. “The students will have to decide for themselves whether to focus on looking for small craters – or whether it might yet be possible to pull off the coup of discovering one of the last remaining large meteorite craters,” says Kenkmann, who received the Baden-Württemberg State Teaching Award for the course in 2012.