The Winchcombe meteorite crashed in Gloucestershire, England Leaving a trail in the night sky on February 28, 2021It came from an asteroid that had been heavily altered by water, broken up and reformed many times.
This is the result of a detailed analysis of the meteorite, fragments of which were found scattered across fields near the village of Winchcombe and even on a family’s driveway. This was the first meteorite fall recovered in the UK since 1991. Thanks to the UK Fireball Alliance’s sky-monitoring video camera network and eyewitness reports, scientists were able to triangulate the approximate area where the meteorite hit.
Search teams were at the scene the next day. They managed to retrieve fragments of the meteorite quickly, within hours of reaching land, and in some cases even earlier. earth atmosphere had managed to severely chemically alter the space rock (although some pieces showed terrestrial contamination). table salt). In total, 602 grams (21.2 ounces) worth of material was collected.
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Despite its fiery journey, the Winchcombe meteorite fragments are as intact as could be hoped for. The meteorite’s composition holds its hidden history, which scientists can reveal with techniques such as advanced transmission electron microscopy and electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, and atomic probe tomography.
These are all methods normally applied to valuable materials transported by ship. Soil with asteroid sample return missions; It’s all thanks to scientists being able to use these sensitive tools on the Winchcombe piece how well-maintained the samples are.
“This level of analysis of the Winchcombe meteorite is almost unprecedented for material not returned directly to Earth from space missions. Apollo program or from samples Ryugu asteroid collected by Hayabusa 2 investigation,” Leon Hicks from the University of Leicester said in a statement.
The research showed that the pieces were made from a breccia in which individual pieces of rock were glued together (not with the cement used to literally build houses, but with a mixture known as a cataclastic mixture). The Winchcombe meteorite is classified as a CM carbonaceous chondrite, a carbon-rich and stony rock. Analyzing the fragments at the nanometer scale, analysis found that the Winchcombe breccia consists of eight different types of CM chondrite, the most common variation of carbonaceous chondrite.
“We were fascinated to reveal how fragmented the breccias were in the Winchcombe sample we analysed,” said Luke Daly from the University of Glasgow, who led the research. “If you imagine the Winchcombe meteorite as a puzzle, what we saw in the analysis was that each of the puzzle pieces were broken into smaller pieces and then mixed into a bag full of pieces from seven other puzzles.”
This suggests that the parent asteroid of the Winchcombe meteorite was fragmented and reformed many times, probably following collisions with other asteroids in the early epochs. solar system‘s history.
Moreover, the meteorite fragments also show clear evidence of being chemically altered. liquid water before falling apart. In some cases, water-altered grains were found right next to unaltered grains, so mixed had the breccia become. There was also an unexpectedly high abundance of carbonate materials such as aragonite, calcite, and dolomite. These are carbon-based minerals, which means that Winchcombe’s parent asteroid once had large amounts of carbon dioxide ice. An event, perhaps an impact, melted this ice and chemically changed the rock, allowing it to form carbonates. This could also explain the surprising carbonate-rich veins found on the asteroid’s surface. bennu by NASA OSIRIS-REx mission.
“This gives us a clearer idea of how it has been hit and reshaped over and over again throughout its life, from the moment it swirled together out of the solar nebula billions of years ago,” Daly concluded.
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However, these findings are not the first discoveries made about the Winchcombe meteorite. Earlier this year, advanced electron microscopy was developed by several groups of scientists. amino acids found and nucleobases within the meteorite. Although these molecules are not directly involved in life as we know it, they are precursors to more complex amino acids known to be biologically useful.
The discovery of water on the parent asteroid of the Winchcombe meteorite could also help understand where water on Earth comes from. The leading theory is that they were brought to Earth by impacts, but were these the effects of impacts? comets or asteroids? Carbonaceous chondrites appear to be the most likely source, potentially making the water-altered Winchcombe samples important evidence if future studies can provide more information about whether the deuterium-to-hydrogen ratio in the asteroid’s water matches that of Earth’s water.
The research was published April 16 in the journal Meteoritics and Planetary Science.