Never-before-seen crystals found in meteorite dust
Researchers have discovered a new type of crystal hidden in tiny grains of perfectly preserved meteorite dust left behind by a massive space rock that exploded over Chelyabinsk, Russia, nine years ago. The 18-metre meteor exploded 14.5 miles above the city of Chelyabinsk in southern Russia, showering the surrounding area in tiny meteorites and avoiding a colossal single collision with the surface.
In a new study, researchers analysed some of the tiny fragments of space rock that were left behind after the meteor exploded, known as meteorite dust. Normally, meteors produce a small amount of dust as they burn up, but the tiny grains are lost to scientists because they are either too small to find, scattered by the wind, fall into water or are contaminated by the environment. However, after the Chelyabinsk meteor exploded, a massive plume of dust hung in the atmosphere for more than four days before eventually raining down on Earth’s surface. And luckily, layers of snow that fell shortly before and after the event trapped and preserved some dust samples until scientists could recover them shortly after.
The researchers stumbled upon the new types of crystals while they were examining specks of the dust under a standard microscope. One of these tiny structures, which was only just big enough to see under the microscope, was fortuitously in focus right at the centre of one of the slides when one team member peered through the eyepiece. If it had been anywhere else, the team would likely have missed it. After analysing the dust with more powerful electron microscopes, the researchers found many more of these crystals and examined them in much greater detail.
The new crystals came in two distinct shapes – quasi-spherical shells and hexagonal rods – both of which were “unique morphological peculiarities”. Further analysis using X-rays revealed that the crystals were made of layers of graphite – a form of carbon made from overlapping sheets of atoms and commonly used in pencils – surrounding a central nanocluster at the heart of the crystal. The researchers propose that the most likely candidates for these nanoclusters are buckminsterfullerene( C 60), ac age-like ball of carbon atoms, or poly hex acyclooc ta de cane (C18H12), a molecule made from carbon and hydrogen. The team suspects that the crystals formed in the high-temperature and highpressure conditions created by the meteor breaking apart, although the exact mechanism is still unclear. In the future the scientists hope to track down other samples of meteorite dust from other space rocks to see if these crystals are a common byproduct of meteor breakups or are unique to the Chelyabinsk explosion.