Pristine piece of space rock found hours after hitting Earth may tell us about the birth of the solar system

Pristine piece of space rock found hours after hitting Earth may tell us about the birth of the solar system

At around 10 p.m. on the night of February 28, 2021, a ball of fire crossed the sky over England. The blazing alien visitor was seen by more than 1,000 people, and its descent was filmed by 16 dedicated UK Fireball Alliance meteor tracking cameras and numerous dashboard and doorbell cameras.

With the time difference to Australia, the team at Curtin University’s Global Fireball Observatory were the first to dig into their camera data, quickly realizing that there could be some very special meteorites to be found around the town of Winchcombe, Gloucestershire.

The news the next morning told locals to watch out for black rocks in their backyards. The Wilcock family discovered a pile of gunpowder and small rocky bits on their driveway. They called in specialists from the Natural History Museum who confirmed it was a meteorite and collected the space rubble for further analysis, all within 12 hours of its landing.

Other fragments were collected from the surrounding area over the following month. In total, the samples totaled around 600 grams of exceptionally pristine asteroid rock from the outer solar system.

We have been studying this precious find with colleagues around the world for 18 months. As we report in a new article in Scientists progress, it is a very fresh sample of an ancient rock formed in the early years of the solar system, rich in water and organic molecules that may have played a crucial role in the origin of life on Earth.

How to Catch a Fireball

Meteorites are rocks from space that have survived the fiery descent through our atmosphere. These are the remnants of our (very) distant past, when the planets were formed, holding clues to what our solar system was like billions of years ago.

There are over 70,000 meteorites in collections around the world. But the Winchcombe meteorite is quite special.

Why? Well, of all the meteorites ever found, only about 50 have been seen falling with enough precision to calculate their original orbit – the path they took to impact the Earth. Determining the orbit is the only way to understand where a meteorite is coming from.

The Global Fireball Observatory is a network of cameras on the lookout for meteorite falls. It is a collaboration of 17 partner institutions around the world, including the University of Glasgow and Imperial College in the UK. This collaboration grew out of Australia’s Desert Fireball Network, led by Curtin University. Of the few meteorite samples whose origin is known, more than 20% have now been recovered by the Global Fireball Observatory team.

Tracking the Winchcombe meteorite

The Winchcombe meteorite was one of the best observed to date. All these observations allowed us to determine that this special sample came from the main asteroid belt, between Mars and Jupiter.

The observation of a fireball from a network of cameras makes it possible to recreate the trajectory of the rock in the atmosphere and not only to calculate its orbit, but also its fall to the ground.

An illustration from Google Earth shows the estimated trajectory and landing site of the meteorite.
Observations from fireball cameras helped scientists calculate the meteorite’s likely landing area. Richard Greenwood / Open University / Google Earth

In an email to the UK team seven hours after the fireball, my colleague Hadrien Devillepoix pointed out that the unusual amount of fragmentation and the orbit could mean we would be looking for a type of meteorite less running.

A space rock usually stops burning when it reaches about 30 km altitude. The rest of the fall is affected by high altitude winds, so it’s not always easy to predict where the meteorite will land.

Curtin’s team played a major role in predicting the drop zone from the fireball data. We’ve recreated the space rock’s flight path to show people where to look for meteorite fragments.

Although many samples were found in the town of Winchcombe, the largest whole chunk was recovered from a field during a dedicated search, found within 400 yards of the predicted position.

The building blocks of life

Winchcombe is a very rare type of meteorite called a carbonaceous chondrite. It is similar to the Murchison meteorite that fell in Victoria in 1969. It contains complex carbon-based molecules called amino acids, which are considered the “building blocks of life”.

These meteorites are thought to have formed at the beginning of the solar system, billions of years ago. They formed far enough from the sun that the water had not completely evaporated and was about to be incorporated into these meteorites. They may have been responsible for bringing water to Earth later.

Carbonaceous chondrites are known to contain water, although most samples have been contaminated by long contact with the Earth’s atmosphere. Some pieces of the Winchcombe meteorite are barely contaminated as they were recovered within hours of its fall. These samples are incredibly pristine and contain almost 11% water by weight.

A space rock delivered to your home

Space agencies are doing a lot to find such fresh space rocks. In 2020, the Japanese Hayabusa2 mission brought back to Earth a few grams of material from a carbonaceous asteroid called Ryugu. Next year, NASA’s OSIRIS-REx will bring home a slightly larger piece of asteroid Bennu.

The speed with which samples of the Winchcombe meteorite were discovered, combined with the precise observations that determined its original orbit in the asteroid belt, puts it closer to material returned from space missions.

Winchcombe’s fireball triangulation, orbital analysis, retrieval and geochemical techniques used to study the history of this space rock required tremendous teamwork.

Besides the scientific secrets it will reveal, the story of the Winchcombe meteorite is a fantastic demonstration of the power of collaboration to unlock the mysteries of our solar system.The conversation

This article is republished from The conversation under Creative Commons license. Read the original article.

Image Credit: Sarah McMullan / UKFN / Global Fireball Observatory

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