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Traces of Life’s Building Blocks Found in Asteroid

It took years for scientists to gain access to the samples that NASA’s OSIRIS-REx mission took from the asteroid Bennu, but the wait is proving to be worth it.


Close up of the sample trays of OSIRIS-REx containing materials from asteroid Bennu
Close up of the sample trays of OSIRIS-REx containing materials from asteroid Bennu | NASA/Erika Blumenfeld & Joseph Aebersold

You may recall that the Osiris-Rex spacecraft successfully picked up materials from an asteroid called Bennu in October 2020, 205 million miles from Earth. It then took almost three years for the NASA probe to come home and drop off its precious cargo in a Utah desert. That happened on 24 September last year.


Now, an astonishing ingredient within the sample materials has been revealed.


A new study published on 29 January in Nature describes an unexpected discovery in the material delivered by OSIRIS-REx: residues of compounds left over by the evaporation of liquid water.


Tim McCoy, the paper’s lead author and the curator of meteorites at the Smithsonian’s National Museum of Natural History, tells Popular Science that the presence of these compounds was completely unexpected. “[Finding them] was a complete surprise,” he says. “Collectively, the team that wrote this paper has hundreds of years of experience examining meteorites and none of us - in fact, nobody - had ever seen some of these minerals.”


This evidence for the presence of liquid water on the ancient body from which Bennu formed provides a tantalizing possibility: Bennu’s progenitor may have seen the first stirrings of life. Brines of the sort that apparently formed in the pockets of liquid water on Bennu’s ancestor provide a favorable environment for the development of complex organic compounds. In a statement accompanying the release of the paper, McCoy said, “We now know from Bennu that the raw ingredients of life were combining in really interesting and complex ways on Bennu’s parent body.”


One leading theory about the origin of the water on Earth is that it was acquired by the capture of such water-rich objects. And if those objects contained brine solutions rich in organic compounds, it’s at least theoretically possible that life may have already been evolving in those environments before their arrival on Earth.

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