A meteorite fragment believed to be older than Earth itself has been discovered in Australia, and it almost washed away before scientists had a chance to get to it.
The recovery operation involved a network of 32 remote camera observatories, a mass of complicated geographical calculations, an aerial spotter, a remotely operated drone, two human searchers, and a whole lot of luck.
It all began on 27 November 2015, when the fragment was hurtled down to Earth's surface from space. Locals in the William Creek and Marree areas of South Australia witnessed its descent, and it was also spotted by the Desert Fireball Network (DFN) - a series of linked digital cameras that monitor the skies above the outback and look for traces of incoming meteorites. Once the rock had been spotted, the race was on to find it.
|Australian Geologists Discover Meteorite Older Than Earth. Photo: Curtin University
After some image analysis, triangulation, and other calculations, the search began in earnest around the Kati Thanda-Lake Eyre area - the lowest natural point in Australia - on December 29. An unmanned drone and a manned light aircraft were used to guide DFN team members, Phil Bland and Robert Howie from Curtin University, to the correct spot, with the assistance of a local search party.
Three days into the search, they found it: a 1.7-kg (3.7-lb) rock embedded in thick salt lake mud, some 42 cm (16.5 inches) below the surface. If the researchers had been a few days later, heavy rains would've washed away the rock for good.
The meteorite fall was witnessed on 27 November by a number of locals in the William Creek and Marree areas, and captured by Desert Fireball Network cameras stationed at William Creek, Mount Barry, Billa Kalina and Wilpoorina.
Desert Fireball Network team members then went to work on image analysis, triangulation and dynamic calculations in order to locate the fall site in Kati Thanda-Lake Eyre.
The three day recovery operation that followed was a complex logistical exercise involving an aerial spotter (piloted by William Creek local Trevor Wright), a remotely operated drone, two searchers on the lake’s surface, and guidance around the area by local Arabana men Dean Stuart and Dave Strangways.
Fellow team member, mechatronic engineer Dr Jonathan Paxman, said the fall site of the meteorite was very difficult to access, being more than six kilometres from a remote part of the lake’s edge, and with the surface quite soft in places due to recent rainfall in the area.
“The fact we have managed to retrieve the meteorite at all is remarkable,” Dr Paxman said.
“Our people worked around the clock to reduce the data, enabling rapid recovery of something that would have been lost if we’d gotten there any later.
“Observations from the air turned out to be quite critical in the end. The impact site had deteriorated quite considerably in recent rain, and as a result was quite hard to see from the ground.”
Team member Robert Howie said the meteorite was embedded in the thick salt lake mud, and covered by softer and wetter mud due to rain which had fallen between the time of impact and recovery. Heavy rainfall has since started to fill Kati Thanda-Lake Eyre with water.
Professor Bland said the meteorite – thought to be a chondrite or stony meteorite – provided an example of material created during the early formation of the Solar System more than 4.5 billion years ago.
“This meteorite is of special significance as the camera observations used to calculate the fall positions have also enabled the solar system orbit of the meteorite to be calculated, giving important contextual information for future study,”
“It demonstrates beyond doubt that this giant machine that we’ve built really works.
“We’ve got a lot more rocks on the ground. This recovery will be the first of many – and every one of those meteorites will give us a unique window into the formation of the Solar System.”
Professor Bland said the team certainly hadn’t expected to spend New Year’s Eve digging for a meteorite on Lake Eyre, but the result had made it all worthwhile.
“A big thanks to the Arabana people as well for giving us access to the lake surface at such short notice. We couldn’t have done this without them.”