Scientists hunt for EC meteorite fragments
Scientists and volunteers have spent the last few days scouring for fragments of a meteorite in the Eastern Cape which entered the Earth’s atmosphere at 72 000km/h just over a week ago.
Known as the Nqweba meteorite, after the nearby town where it was discovered, the meteorite has also guaranteed 9-year old Eli-zé du Toit a place in history: she saw the dark rock fall from the sky and land near a wild fig tree in the garden while sitting on her grandparents’ porch in Nqweba.
Professor Roger Gibson from Wits University said it was a once-in-a-lifetime dream event for scientists.
“We only have a meteorite recovered from a set of lights in the sky, what we call a bolide. The last one was 1973 in Lichtenberg, so it is 51 years since that last happened.”
Gibson said while they had spotted meteorites over South Africa many times they hadn’t been able to find the fragments, until now.
“We’ve come close several times, but this event is unusual for us because not only do we have the fireball, not only do we have the eyewitness accounts, we have this rock literally being seen falling out of a tree. I don’t know if there are more than half a dozen occurrences in the history of the world where literally the rock has been seen before it hits the ground.”
He said Eli-zé had made the most amazing observation. “And then, of course, she went over and picked it up immediately. She didn’t ignore it. She literally, within seconds, had touched this rock that five minutes earlier was probably floating in outer space and hadn’t ever touched a planet before.”
When this happened at about 8.51am on Sunday, August 25, people from as far afield as the Free State and the Western Cape saw a bright blue-white and orange streak of light in the sky.
After splitting into several smaller fragments it disappeared and witnesses heard loud explosions.
At the time three teenagers, Zoë van der Merwe, MC Fereira and Stephen Sharp, were sitting on a dune at Cape St Francis Bay, when they spotted a bright flash and began filming it as several streaks of light moved across the sky before disappearing.
The sighting was followed by three loud explosions and a rumble and then they felt the sound vibrating through their bodies as the ground shook.
Experts said the rumbling thunder sound was the sonic booms caused by the meteorites as they broke through the sound barrier. It can sometimes be heard hundreds of kilometres away.
Gibson said a collaborative scientific investigation involving several leading universities in the country was now under way.
He said once he and his colleagues from other universities heard about the occurrence, it was a race against time to reach the Nqweba meteorite as soon as possible.
“They’re world events so that’s the first reason; to try to secure these because they are heritage items in South Africa according to the Heritage Resources Act of 1999. The second thing is, we want to describe them and the techniques we use to describe them; we want as little contamination from Earth because this is a foreign world. This rock never encountered oxygen or water before in its existence. And its existence goes back almost to the formation of the Sun,” said Gibson.
He said there were people who chased these events all over the world to collect meteorites.
“And this was a global event because there are sensors all over the world that monitor the upper atmosphere for incoming objects.
“It was mainly developed during the Cold War to try to monitor when rockets were being fired en masse into space, so an attack with intercontinental ballistic missiles was going to happen.
“We realised there were so many things shooting into the upper atmosphere all the time and these sensors are able to pick them up. In this case, the US sends the information of these events to Nasa and the computers and the clever people there churn out all the data. They told us this event had happened.”
A meteorite is a remnant of space rock that reaches the Earth’s surface. It enters the Earth’s atmosphere with a light streak called a bolide and if it’s large enough, it might hit the Earth’s surface or just burn up because of friction as it enters the planet’s atmosphere.
It can also cause considerable damage as witnessed when a meteor exploded in the sky over Chelyabinsk, southern Russia, in February 2013. The shockwave from the exploding meteorite injured 1 500 people and damaged 7 200 buildings in the region.