Hard on the heels to discover what could be a massive crash crater deep under the Greenlandic ice, the researchers believe they might have discovered another independent such structure nearby.
The new supposed crater is about 36 kilometers wide and, as the first structure, has not yet been defined as a crash crater. There are many more crater-like features on Earth than there are actual craters formed by meteorites that slam into the planet.
"I started to ask myself," is this another blow crater? Does the underlying data give the idea? "Author author Joe MacGregor, a glaciologist at NASA's Goddard Space Flight Center in Greenbelt, MD, said in a statement. "Helping to identify a large crater under the ice was already very exciting, but now it looked like there could be two of them." [In Pictures: The Giant Crater Beneath Greenland Explained]
MacGregor was also involved in identifying a slightly less possible batsman called Hiawatha, which was announced in November. In addition to its striking circular shape and the height features of an edge and a central height that scientists expect in a battleground, the Hiawatha discovery also finds sports minerals that have apparently been suddenly shocked by a dramatic event as a meteorite impact.
The new candidate lacks a similar mineral footprint and is believed to be from a meteor based only on elevation data collected by 11 different remote sensor programs. These data show a striking depth in the Earth's surface about 114 miles (183 km) southeast of the location of the first structure. The other structure is less circular than Hiawatha, but the researchers believe they find the same characteristic rims and inner peaks.
Despite the two features, the researchers are approaching that, although both were formed by meteorites that hit the ground, they were probably created separately. The team believes that the newly discovered structure formed more than 79,000 years ago before any of the ice over it was in place.
It leaves a large number of potential ages, so the team added another technique to try to estimate its age. By modeling what such a battleground might have looked like when it was first formed, the researchers were able to calculate how many thousands of years of ice erosion would have been needed to create its present form. This process suggested the structure that was first formed between 100,000 and 100 million years ago.
This range seems to be older than the Hiawatha structure, as originally dated between 3 million and 12,000 years ago; Researchers on this project suspected the alleged crater was on the younger side of this area.
Both potential impact craters must be verified as such before the researchers can tell about the history of the meteorites that are slipping into the ground. But the team is clearly still exciting in the news of studying these massive structures hidden deep under the ice – in this case worth over a mile (2 km) worth.
"We've explored the land in many different ways, from land, air and space – it's exciting that discoveries like these are still possible," MacGregor said.
The research is described in a paper published today (February 11) in the journal Geophysical Research Letters.