The renowned Winchcombe meteorite from the U.K. is aiding scientists in understanding distant asteroids in our solar system. Analyzing its chemical composition and comparing it with asteroid data can unveil mysteries of our cosmos. Since its 2021 landing in Gloucestershire, researchers have been decoding its secrets, granting a unique view of otherwise hard-to-study remote asteroids.
In a fresh paper in Meteoritics & Planetary Science, scientists delve into the meteorite's minerals, elemental makeup, and water content. This data on bulk composition is now guiding the study of similar space rocks.
Confirming its type as a CM carbonaceous chondrite, this research aligns with the meteorite's role as an ancient solar system relic. Dr. Helena Bates, lead author, highlights that accessing “bulk information” about meteorites aids in comparing distant asteroids.
“We're skilled at gathering this information,” adds Dr. Bates, an asteroid researcher at the Museum, emphasizing their practiced technique.
Why is the Winchcombe meteorite important?
On a Sunday evening, February 28, 2021, a stunning fireball streaked across the sky in western England, observed by numerous people. The next day, inhabitants of a Winchcombe house awoke to discover fragments of dark rock on their driveway. Swiftly, nearly 600 grams of this meteorite were collected and transported to the Museum for comprehensive examination.
The U.K. usually experiences two to three small meteorite falls each year, but retrieval is often challenging due to the locations. The Winchcombe incident was especially thrilling because it marked the first meteorite recovery in the country in over three decades.
This occurrence holds significance because once a meteorite lands on Earth, contamination sets in rapidly. In the case of Winchcombe, since the pieces were collected within 12 hours, the sample quality is comparable to those procured from asteroids by probes. Hence, it holds exceptional value for research.
Dr. Helena, discussing the study, explains, “We were able to examine the mercury content in the sample. Mercury measurement in meteorites is complex due to terrestrial contamination. Winchcombe's pristine state upon landing allowed us to precisely measure its mercury content, offering insights not often attainable.”
Believed to originate from the asteroid belt between Mars and Jupiter, the Winchcombe meteorite was once part of a larger asteroid for millions of years. A collision caused it to fragment and journey through space for 300,000 years until Earth's gravity pulled it in.
How have scientists been studying the meteorite?
Over the past couple of years, scientists have been meticulously studying the Winchcombe meteorite to gain insights into its asteroid origins.
In their quest, researchers dissolved a sample of the meteorite to examine its specific elements. The bulk elemental composition analysis revealed Winchcombe's alignment with a typical CM carbonaceous chondrite. A closer look at iron content indicated similarity with other CM carbonaceous chondrites in terms of iron abundance and the oxygen exposure of the iron.
The team also scrutinized the meteorite's bulk mineralogy by subjecting a 50-milligram sample to X-rays. The bending of X-rays provided information about atoms and bonds within the sample, unveiling the mineral makeup.
The mineral study suggested that Winchcombe had encountered water, evident from its clay-rich and water-bearing mineral content. The researchers sought to determine the source of this water. They heated a meteorite sample to 1,000 degrees and measured the change in weight as it heated up. Different minerals dehydrate at varying temperatures, allowing them to identify the water-holding minerals.
Given water's essential role in supporting life on Earth, scientists aim to unravel its origins and arrival. To compare the meteorite with asteroids, infrared spectroscopy was employed. By shining an infrared laser at the meteorite and analyzing the reflected light, characteristic gaps indicative of specific minerals were identified. This data was then compared to asteroid information.
Dr. Helena elucidates, “In essence, we recreated asteroid observations in a lab setting. By characterizing the meteorite and simulating its appearance in space, we can draw comparisons with existing celestial bodies.”
The study focuses on comparing Winchcombe with C complex asteroids, which exhibit signs of water-alteration. Notably, the Museum's involvement in asteroid sample return missions, OSIRIS-REx and Hayabusa2, aids this comparison. Additionally, vast data collected by telescopes provides a wealth of information about C complex asteroids, enriching the analysis of Winchcombe's unique attributes.
Source: Natural History Museum