Samples from asteroid Bennu contain the key ingredients of life

We’ve had a first look at samples from a 4.5-billion-year-old asteroid and they are full of carbon and water – the necessary ingredients for life.

“As we peer into the ancient secrets preserved within the dust and small rocks of asteroid Bennu, we are unlocking a time capsule that offers us profound insights into the origins of our solar system,” said Dante Lauretta at the University of Arizona, the principal investigator on NASA’s OSIRIS-Rex mission, in a statement. “The bounty of carbon-rich material and the abundant presence of water-bearing clay minerals are just the tip of the cosmic iceberg.”

The samples were extracted from Bennu by the OSIRIS-REx spacecraft in 2020. The spacecraft travelled millions of kilometres in order to return to Earth. The sample-filled capsule touched down in the Utah desert on 24 September. The capsule was then transported to NASA’s Johnson Space Center in Houston, where researchers started analysing its contents in clean rooms built especially for the mission.

OSIRIS-REx’s goal was to collect about 60 grams of material from Bennu to allow researchers to study space rocks that formed billions of years ago and were not subsequently changed by heat or water, as happens to meteorites that hit the Earth. The capsule actually contained much more material. In fact, the researchers have not yet analysed all its contents. Instead, they studied the charcoal-coloured dust and tiny Bennu pebbles (see image above) that settled on the lid and around the base of the sample-holding canister. They subjected this material to a battery of analytical tests, which revealed the presence of water, carbon and several organic molecules.

“Carbon and water are not life, but they are the building blocks that life needs, and there are other pivotal materials and minerals there,” says Timothy Glotch at Stony Brook University in New York. He says that researchers could predict some of the elements that have been identified in the samples, but analysing them further will show how water may have changed the rocky asteroid over time, beginning early in the development of the solar system.

Paul Byrne at the Washington University in St. Louis says that this may have implications for how water came to Earth and the timeline of water’s presence on other planets. Learning just how much water there is on Bennu could tell us “whether Earth was born wet, or born dry and then water was brought to it”. Researchers could extrapolate this understanding to planets like Venus that are currently dry but may have once carried water, he says.

NASA’s researchers will continue analysing and characterising the samples for the next two years. But they will preserve at least 70 per cent of the material for further research by scientists worldwide and in the future.