On February 28, 2021, a meteorite fell in the UK for the first time in 30 years and was later recovered by scientists. Today, there is an international effort to study this space rock and learn more about its place in the early solar system.
This meteorite is named after Winchcombe, the Gloucestershire town where several fragments were recovered, including one that landed in the driveway of a family home.
The meteorite was formed 4.5 billion years ago in the far outer solar system, beyond the orbit of Jupiter. We call such objects primitive because they contain some of the earliest solid materials formed in our cosmic environment, offering insight into a time when our solar system was in its infancy.
Over time, much of this solid material merged into larger objects, eventually leading to the formation of planets. Some of the early building blocks that were not consumed in this process of planetary assembly are present today as asteroids or even smaller objects. The Winchcombe meteorite is one such celestial body.
Some of these free-roaming planetary building blocks may have been responsible for providing water to the early Earth. Therefore, Winchcombe can glimpse the activity of water on solid bodies in the ancient solar system.
Away through space
Winchcombe is a rare type of meteorite known as CM chondrite. These meteorites are characterized by high concentrations of water and organic matter (molecules with chains of carbon atoms), both of which are essential ingredients for the origin of life.
We know the path through space the Winchcombe object took – its orbit – before it fell to Earth. It is one of only five primitive, water-carrying chondrites for which scientists have this information. Knowing its orbit, we can pinpoint where in the solar system it came from.
The pieces of this meteorite were recovered very quickly – within 12 hours of arriving on Earth. This means there was little time for water from Earth’s atmosphere to react with and contaminate the meteorite. Together with the meteorite’s rarity, primitive features and distant origin, its rapid recovery makes it an ideal candidate for studying the role of asteroids in the early solar system.
The meteorite was probably once part of a larger asteroid. But when we examined the pieces of the Winchcombe object under the microscope, it quickly became clear that it was not just one rock, but many—a complex mix of fragments loosely held together. This structure is the result of collisions between larger asteroids in space.
The debris field created by the collision then merged to form a new population of smaller second-generation asteroids called debris pile objects because of their loose, blocky configuration. Winchcombe emerged from one of these rubble piles – fragmented remains of the diverse rocky objects that existed in the age before planets.
Space mud
Each rock fragment that makes up the Winchcombe meteorite records a clear history, revealing differences in the amount of water it interacted with, for example, suggesting that the original asteroid had a complex structure.
These observations indicate either variable amounts of water on that parent body, which condensed as ice as the asteroid grew, or the uneven flow of water through the asteroid. When space rocks come into contact with liquid water, they begin to change, forming an unusual form of dark black, fine-grained “space mud”.
Researchers from all over the world are jumping at the chance to study these minerals because their crystal structure contains molecules of the original water that flowed on these asteroids.
A group of scientists has carefully measured the different isotopes (or chemical forms) of the hydrogen present in Winchcombe. Along with oxygen, hydrogen is one of the two chemical elements in water. The scientists’ findings showed that the water in the meteorite is very similar to the water on Earth.
This reinforces a theory that asteroids played a critical role in providing water to the early Earth and thus generating the oceans we see today.
Catastrophic collision
At one point, chemical reactions between water and rock were halted by the catastrophic collision with another asteroid. This event shattered the meteorite’s parent body. Most of the rock fragments in the Winchcombe meteorite are very small, less than 1 mm in size. This pattern of small pieces is evidence of the high-energy collision, but also the signature of a faint asteroid.
As our understanding of planetary building blocks grows, we increasingly recognize that the types of planetary bodies represented by the Winchcombe meteorite no longer exist in their original forms.
Most, if not all, small asteroids (less than 10 km in diameter) are probably rubble. Winchcombe is a relic of that era and a testament to the fate of most asteroids. We can sum up their history in a few simple words: hot and wet, then smashed to rubble.
Studying Winchcombe has also helped us understand how these types of meteorites break up in the atmosphere and therefore why they are rarely found as large rocks.
The research on Winchcombe continues and there are many more scientific questions we hope to answer. One particularly interesting study relates to the type and amount of organic matter at Winchcombe and whether organic matter delivered by meteorites played a role in providing nutrients – essentially food – for emerging life on Earth.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Dr. Martin D. Suttle has received funding from the UKRI Science and Technology Facilities Council (STFC).