Scientists discover evidence of a potentially new asteroid

22 Dec 2020

A false-colour micrograph of the meteorite sample. Image: © NASA/USRA/Lunar and Planetary Institute

A team of researchers studying a small meteorite shard said it is likely to have come from a previously unknown parent asteroid.

While hundreds of thousands of asteroids have been discovered by researchers, scientists and amateur observers all over the world, it only a fraction of what is likely to exist in space. The more asteroids that are discovered, the more they can be studied and analysed.

Now, scientists from the Southwest Research Institute (SwRI) in Texas have identified a potentially new meteorite parent asteroid by studying a small shard of a meteorite that arrived on Earth a dozen years ago.

The SwRI-led team was tasked with studying the composition of a 50mg piece of meteorite, which indicated that its parent body was an asteroid roughly the size of Ceres, the largest object in the main asteroid belt, and that it was formed in the presence of water under intermediate temperatures and pressures.

In a paper published in Nature Astronomy, Dr Vicky Hamilton said carbonaceous chondrite meteorites such as this one are significant because they record the geological activity during the earliest stages of the Solar System and provide insight into their parent bodies’ histories.

“Some of these meteorites are dominated by minerals, providing evidence for exposure to water at low temperatures and pressures. The composition of other meteorites points to heating in the absence of water. Evidence for metamorphism in the presence of water at intermediate conditions has been virtually absent, until now.”

Hamilton said that spectral analysis identified a range of hydrated minerals, in particular amphibole, which is a rare find in carbonaceous chondrite meteorites. It indicates “intermediate temperatures and pressures and a prolonged period of aqueous alteration” on a parent asteroid of at least 643km in diameter, but it could be up to 1,770km.

Key information about the formation of the Solar System

This discovery follows two sample collecting missions from known asteroids Ryugu and Bennu. In October, NASA’s OSIRIS-REx mission team collected more than 60g of surface material from the Bennu asteroid, with the sample due to return to Earth in 2023. Meanwhile, Japanese spacecraft Hayabusa2 returned to Earth earlier this month with dust from the Ryugu asteroid.

The samples from Ryugu could give researchers important insights into the early evolution of planets and help to explain the origins of water on Earth. According to Nature, approximately 10pc of the material from Ryugu will be sent to NASA in December 2021 in exchange for samples from Bennu.

Following the success of the Ryugu mission, Ed Kruzins, director of the Canberra Deep Space Communication Complex at the Commonwealth Scientific and Industrial Research Organisation, said: “The samples containing precious asteroid material will provide scientists with key information about the formation of the Solar System.”

Jenny Darmody is the deputy editor of Silicon Republic

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