Dust scooped up from an asteroid by a NASA spacecraft 200 million miles from Earth has been found to contain material that is older than our sun.
The first major study of the chemistry of the asteroid Bennu identified “presolar grains” – stardust that condensed around dying stars billions of years ago.
An international team of scientists, including some from London’s Natural History Museum, say the samples are a snapshot of the early Solar System, more pristine than any meteorite on Earth.
Pic: Trustees of the Natural History Museum
In one of NASA‘s most audacious missions the spacecraft Osiris Rex briefly touched the surface of Bennu, using a robotic arm to collect around 120g of material which was packed into a capsule and returned to Earth in 2023.
Chemical analysis has now allowed scientists to piece together Bennu’s origins in the cold, dense gas and dust of the early Solar System.
Bennu seen from the Osiris-Rex.
Pic: NASA/AP
Professor Jessica Barnes, from the University of Arizona, who is one of the study’s authors, said: “Our data suggest that Bennu’s parent asteroid formed in the outer parts of the solar system, possibly beyond the orbit of Saturn.”
But the analysis also found a smorgasbord of other material in the sample, including organic matter from the outer Solar System and the interstellar medium – the gas and dust between stars – as well as high temperature materials that are thought to have formed close to the sun before drifting outwards.
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Pic: Trustees of the Natural History Museum
Osiris-Rex spacecraft touches the surface of asteroid Bennu in 2020. Pic: NASA/AP
Professor Sara Russell, planetary scientist at the Natural History Museum and another of the study’s authors, said: “We’re looking at a unique snapshot of the outer Solar System at [the time of] the birth of our sun.
“Some of these grains have survived billions of years of Solar System evolution almost untouched and can tell us more about the environment in which planets were born.”
Further research conducted at the Natural History Museum has found evidence in the samples of water-driven chemical reactions that began over 4.5 billion years ago, before Earth had fully formed.
The asteroid sample has proved to be an extraordinary window into the formation of the Solar System.
Earlier this year, scientists announced it contained the building blocks of life.
“Studying Bennu has given us the opportunity to investigate a novel type of space rock, and we are learning new things about it every day,” said Professor Russell.
“The lack of reaction with the Earth’s atmosphere has given us the opportunity to study the history of the asteroid, and the evolution of the minerals it contains, in incomparable detail.”
