The chemical building blocks of life have been found in the grainy dust of an asteroid called Bennu, analysis shows. The space rock samples, collected by a NASA probe and brought back to Earth, contain a wealth of minerals and thousands of organic compounds, the BBC reports.
Among them are amino acids, which are the molecules from which proteins are made, as well as nucleobases – the basic building blocks of DNA.
This doesn't mean that life ever existed on Bennu, but it supports the theory that asteroids brought these vital ingredients to Earth when they hit our planet billions of years ago.
Scientists believe that these same compounds could have been brought to other worlds in our solar system.
"What we've found out is incredible," said Professor Sarah Russell, a cosmic mineralogist at the Natural History Museum in London. "It tells us about our own origins and allows us to answer these really, really big questions about where life began. And who doesn't want to know how life began?"
The findings were published in two papers in the journal Nature. Collecting a piece of Bennu was one of the boldest missions NASA has ever undertaken.
A space probe named Osiris Rex deployed a robotic arm to collect a 500-meter-wide piece of the asteroid, which was then packed into a capsule and returned to Earth in 2023.
About 120 grams of black dust was collected, which was shared with scientists around the world. This may not sound like a lot of material, but it turned out to be a real treasure.
"Every grain tells us something new about Bennu," said Russell, who studies these tiny particles.
About a teaspoon of the asteroid has been sent to scientists in the UK. New research has shown that the space rock is packed with nitrogen- and carbon-rich compounds.
This includes 14 of the 20 amino acids that life on Earth uses to build proteins and all four ring-shaped molecules that make up DNA - adenine, guanine, cytosine and thymine.
The study also found various minerals and salts, suggesting that water once existed on the asteroid. Ammonia, which is important for biochemical reactions, was also detected in the sample.
Some of these compounds have been seen in space rocks that have fallen to Earth, but others have not been detected until now.
"It's just incredible how rich it is. It's full of these minerals that we haven't seen in meteorites before and combinations of them that we haven't seen before. It was really exciting to study this," Russell said.
This latest research adds to the growing evidence that asteroids brought water and organic material to Earth.
"The early solar system was a very turbulent place and there were millions of asteroids like Bennu flying around," explained Dr Ashley King, from the Natural History Museum.
The idea is that they bombarded the young Earth, seeding our planet with the ingredients that gave us oceans and made life possible.
However, Earth wasn't the only world hit by space rocks. Asteroids probably hit other planets as well.
"Earth is unique in that it's the only place we've found life so far, but we know that asteroids brought those ingredients, carbon and water, throughout the solar system," King said.
"And one of the big questions we're trying to answer now is, if the right conditions are there, why do we have life here on Earth – and could we potentially find life elsewhere in our solar system?"
That's a key question that scientists will continue to try to answer.
They have decades of research ahead of them on the dust brought back from Bennu, as well as parts of our cosmic neighborhood that still need to be explored.
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