NASA’s first asteroid samples came from ‘ancient ocean world’: Scientists find fragments from Bennu are high in carbon and water

The first asteroid sample brought back to Earth may have come from an ancient oceanic world, which may have had suitable conditions for life.

The initial analysis, conducted in October, determined Bennu contained large amounts of water and carbon – and scientists suggested that such asteroids may have delivered the building blocks for life on Earth.

Now, researchers at the University of Arizona believe Bennu was part of a water-rich planet that existed billions of years ago.

The team determined that some of the dark rocks on the asteroid are coated in a thin crust of brighter material that has been observed on Saturn’s moon Enceladus, which is believed to have a a global ocean of liquid salty water.

‘My working hypothesis is that this was an ancient ocean world,’ Dante Lauretta at the University of Arizona and the mission’s principal investigator told NewScientist.

He added that the asteroid sample contains structures that could provide clues about the origins of life.

Lauretta has not yet published his hypothesis or findings but said his analysis of the material over the last few months showed that much of the rock is made of clay, including minerals called serpentites. 

These materials form on Earth when rock is pushed into a seabed and exposed to water creating an exothermic reaction which generates heat.

The team also noticed that brighter material covered Bennu’s dark rock and Lauretta said it is an extremely rare calcium and magnesium-rich phosphate mineral.

Because the same material is found on Enceladus, scientists have theorized that life may have started in the icy seabed. 

Fabian Klenner at the University of Washington in Seattle told NewScientist: ‘There are indeed similarities between the mineralogy of Bennu and what has been found on Enceladus.’

The researchers aren’t claiming that the findings showed life existed on the planet, but that ‘origins of life is a big area of study for these samples.’

NASA’s OSIRIS-REx mission dropped off samples from the asteroid Bennu in 2023 after launching to the space rock in 2016.

The space agency sent a probe to the 1,250-foot asteroid Bennu in 2020 as part of a landmark mission to collect samples. 

The mission brought back about eight ounces of debris, which NASA believes holds building blocks from the dawn of our solar system and could provide clues to understanding how life formed on Earth.

NASA chose to sample Bennu because it is believed to be rich in organic compounds.

Bennu is a remnant of the formation of the solar system, and NASA believes the mission could provide insight into Earth’s history because weather, erosion, and plate tectonics have wiped away all evidence of how Earth formed.

‘We’re going back to the dawn of the solar system, we’re looking for clues as to why Earth is a habitable world, this rare jewel in outer space that has oceans, it has a protective atmosphere,’ Lauretta said after receiving samples from the OSIRIS-REx mission in September.

‘The biggest question is the origin of life and we believe that we’re bringing back that kind of material, maybe the seeds of life that these asteroids delivered at the beginning.’