Astronomers ended 2015 by finding a precious meteorite just hours before floods would have hidden it forever. They then narrowly avoided getting trapped by the same floods. All following remarkable detective work to locate the space rock.
Most meteorites are found without us knowing anything about their path to Earth. “It's like having a bunch of random rocks dumped in your backyard,” Curtin University Professor Phil Bland told IFLScience. However, if we have photographic evidence of their path through the atmosphere, we can calculate their orbits, making meteorites we can match to these images terrifically valuable.
Bland told IFLScience it is sometimes possible to match the meteorite to a family of asteroids, and sometimes even a specific asteroid from which the meteorite came. Almost all meteorites are 4.5 billion years old, older than the Earth, and establishing their origins could tell us how rock formation differed with distance from the Sun.
One of the camera images produced by the Desert Fireball Network that allowed researchers to calculate the landing site and find the meteorite. Curtin University/Desert Fireball Network
Half of the 20 meteorites whose paths have been photographed were pure luck, according to Bland, such as the one that landed near a football match, its path filmed by numerous fans. The rest resulted from a network of cameras that scan the skies looking for fireballs (bright meteors) and compute the landing sites of those large enough to make it to the ground.
Bland leads the Desert Fireball Network, 32 cameras strategically placed across Western and South Australia. “Our advantage is that we are doing this in a place where we know we can find meteorites on the ground,” Bland told IFLScience. Other networks lose most of their tracked meteorites in the vegetation.
The meteorite Bland's team has retrieved landed in Kati Thanda-Lake Eyre on November 27. This dry lakebed normally represents a perfect place to spot something unusual, but big rains have produced one of its rare, but spectacular, floods. The layer of mud and salt deposited in the process would have left no hope of finding the meteorite in their wake, inspiring a desperate quest to find the landing site in time.
Combining trails picked up by four cameras, reports from locals, aerial spotters, a drone and the local knowledge of the Arabana indigenous population, Bland hand-dug the 1.7-kilogram (4-pound) rock from a 42-centimeter (17-inch) hole at a site 6 kilometers (4 miles) from the lake's edge. After hightailing it back to the nearest hotel on New Year's Eve, Bland says the team had expected to be flooded in, and may have been the last car out before the dirt track was shut for the floods' duration.
Professor Phil Bland celebrates finding his first Desert Fireball Network meteorite. He called the project cheap compared to space agencies' billion dollar missions to return samples from asteroids. Curtin University/Desert Fireball Network
The team have records for 10 other fireballs they expect to have produced meteorites, but Bland isn't worried about floods at these locations. The success, he says, “demonstrates beyond doubt that this giant machine that we’ve built really works.”
The rock itself is a chondrite, easily the most common type of meteorite, but Bland hopes isotopic analysis will reveal when it was knocked off a larger object and help us determine its history.