A massive asteroid broke apart within the inner Solar System and showered the Earth and Moon with up to fifty quadrillion kilograms of meteoroids, say a trio of Japanese scientists. That's approximately 30 to 60 times more cosmic material than the Chicxulub prang that thoroughly ruined the dinosaurs' day.
The academics analyzed data from Japan's JAXA Moon orbiter Kaguya, and lunar regolith collected by NASA’s Apollo missions, and found tantalizing clues that several large craters on the Moon formed at the same time, some 800 million years ago. Eight out of the 59 cavities studied dated back to a time just before the Cryogenian period, when the Earth was covered in ice.
One of the most prominent structures, the Copernicus crater, is surrounded by hundreds of smaller holes that were also created at the same time. “We determined the age distribution of lunar craters over three billion years, and we discovered the sporadic peak around several hundred million years ago,” Kentaro Terada, first author of a study into the findings, published in Nature Communications, and a professor of the planetary science group at Osaka University, told The Register.
The team estimated the total mass of the meteoroids left over from the ancient asteroid that broke apart by looking at the size of the craters. Bigger holes hint that the impact object is very large and heavy itself.
Two billion years ago, snowball Earth was defrosted in huge asteroid crash – and it's been downhill ever sinceREAD MORE
“There is a scaling-law model, which describes the relationship between the diameter of the crater and the mass of impact. Thus, we estimate the total mass of the impactor to the Moon. [Previous research] estimated the collision probability with Earth and Moon after the disruption of the asteroid,” Terada explained.
The evidence points to a large object measuring some 100 kilometres across, probably in the Eulalia asteroid family, which likely fragmented into meteoroids when it collided with other space rocks, and at least some of the debris rained down on the inner Solar System. The team believes that up to 5 x 1016 kilograms littered the Earth and Moon.
It’s difficult to confirm whether our world was indeed sprinkled with the fragments since evidence of these meteor impacts on our surface will have disappeared over time from erosion or been covered up by layers of rocks formed from volcanic eruptions
But there is more evidence that the researchers can try to find, such as determining the age of other asteroids from the Eulalia family. Some scientists reckon the asteroid Ryugu formed from a larger parent body from the Eulalia family – and JAXA's Hayabusa2 probe is due to return to Earth this December from Ryugu with a sample of the rock.
“My next research plan is to date the collected sample from asteroid Ryugu ... If we find the age to be 800 million years from the Ryugu sample, I will be so excited,” Terada added. ®