Tory Shepherd
Tory Shepherd is an Adelaide-based freelance journalist who has covered Space 2.0 for The Advertiser.
22 million years ago, something smashed into the big, bright Vesta asteroid, ejecting a meteoroid into space.
Scientists have mapped the long journey that meteroid – now a meteorite known as Motopi Pan – took: all the way from Vesta, which orbits the sun, to the Kalahari desert.
A chunk of rock blasted into space 160 million kilometres away was captured by CCTV as the fireball crashed to Earth.
It’s the first time such a voyage has been mapped.
The Australian National University SkyMapper Telescope, which is used to spot space junk and dangerous asteroids, played a crucial part in the international effort.
ANU astronomer Associate Professor Christian Wolf says the long-distance traveller broke up 27 kilometres above ground, at which point it was “20,000 times brighter than the full moon”.
His colleague at ANU, Dr Christopher Onken, analysed the images from SkyMapper’s camera.
“I could hardly believe my eyes when I came upon a little object that appeared to be moving across images taken by SkyMapper,” he says.
According to Onken, these images of the object just before it entered Earth’s atmosphere were SkyMapper’s biggest contribution.
“They helped to pinpoint both the search area for the meteorite fragments on Earth and the meteor’s origin in space.”
And that, he says, allowed them to trace the trajectory back to Vesta, the only asteroid bright enough to be (“sometimes”) visible to the unaided eye.
“The oldest known materials found both in Vesta and in the meteorite are Zircon grains that date back to more than 4.5 billion years ago, during the early phase of the Solar System,” he says.
Researchers from ANU and Western Australia’s Curtin University worked with scientists from NASA Ames Research Center and the SETI Institute to plot Motopi Pan’s path, which has been published in the journal Meteoritics and Planetary Science.
Curtin astronomer Dr Hadrien Devillepoix said their analysis showed the meteorite had been “deeply buried” under Vesta’s surface before it was ejected.
According to NASA, Vesta is nearly big enough to be classified as a dwarf planet. Fellow asteroids have collided with it several times, forming huge craters and spawning a range of meteorites that have been found on Earth.
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