Water and organic matter found on the surface of an asteroid could explain how life formed on Earth, the first ever sample reveals.
Researchers from Royal Holloway, University of London, analysed a single “grain” from the asteroid, known as ‘Itokawa’, and discovered it had evolved chemically over time.
Their findings, published today in the journal Scientific Reports, reveal “complex details” of the asteroid’s history and could help explain the evolution pathway of Earth, they said.
Samples taken from the asteroid were returned from the inner Solar System by the Japan Aerospace Exploration Agency’s first Hayabusa mission in 2010.
A team of international researchers then analysed a single grain of the sample, nicknamed ‘Amazon’, and discovered both unheated and heated organic matter.
“The organic matter that has been heated indicates that the asteroid had been heated to over 600°C in the past,” said Dr Queenie Chan from the Department of Earth Sciences at Royal Holloway.
“The presence of unheated organic matter very close to it, means that the infall of primitive organics arrived on the surface of Itokawa after the asteroid had cooled down.”
Itokawa has been constantly evolving over billions of years, the findings suggest, by taking in water and organic materials from foreign extra-terrestrial material – similar to Earth.
The asteroid would have undergone extreme heating, dehydration and “shattering” due to a catastrophic impact, the researchers said.
That impact is likely to have taken place “rather recently”, 1.3 to 1.4billion years ago, they added.
Despite this, Itokawa reformed from the shattered fragments and “rehydrated itself” with water from carbon-rich meteorites or infall of dust.
Itokawa is an S-type asteroid, similar to most of Earth’s meteorites, and these latest findings reveal they contain “raw ingredients of life”.
The findings also change previous views that the origins of life on Earth, which focused on C-type, carbon rich asteroids.
“Studying ‘Amazon’ has allowed us to better understand how the asteroid constantly evolved by incorporating newly-arrived exogenous water and organic compounds,” Dr Chan said.
“These findings are really exciting as they reveal complex details of an asteroid’s history and how its evolution pathway is so similar to that of the prebiotic Earth.
“The success of this mission and the analysis of the sample that returned to Earth has since paved the way for a more detailed analysis of carbonaceous material returned by missions such as JAXA’s Hayabusa2 and NASA’s OSIRIS-Rex missions.
“Both of these missions have identified exogeneous materials on the target asteroids Ryugu and Bennu, respectively. Our findings suggest that mixing of materials is a common process in our solar system.”