Asteroid Bennu Holds Secrets to Life’s Origins

Asteroid Bennu not only held water at some point in its distant past but also contains briny residue that harbors some of the crucial building blocks for life, according to a team of scientists that studied samples of the space rock.

New Discoveries on Bennu

The brine contains compounds that have never been previously observed in asteroid samples, including compounds of sodium carbonate. The brine can also be distinguished from brine samples on Earth, as it is much richer in phosphorus—an element abundant on asteroids but uncommon on Earth. The team’s findings shake up the story of Bennu, whose rocky bits were valiantly collected by NASA in 2020, and hint at the ways life may have taken root from the chemical cocktail of the cosmos.

Breakthroughs in Asteroid Research

Two studies published today in Nature and Nature Astronomy reveal some of the first analyses done of the Bennu samples. The papers describe briny residue found in the samples, which differs from the composition of Earth’s brines, as well as protein-building amino acids and the five nucleobases that form the building blocks of RNA and DNA. In other words, the sample con…eladus is an exciting venue for astrobiology—the search for extraterrestrial life—because it is thought to harbor a subsurface ocean of liquid water and has been caught spitting up other ingredients for life, including hydrogen cyanide and phosphorus.

Astrobiologists React to the Findings

In 2023, astrobiologists told Gizmodo just how significant the Bennu samples could be for understanding the building blocks of life and how water arrived on our primordial world. The new findings add promise and intrigue to that hype. "This is the kind of finding you hope you’re going to make on a mission," McCoy said. "We found something we didn’t expect, and that’s the best reward for any kind of exploration."

The Future of Asteroid Research

The wealth of samples taken from Bennu—again, nearly double what scientists had planned for—will continue to provide valuable insights into the history of our solar system and the distribution of key ingredients for life within it. So far, the samples are delivering on the promise that made OSIRIS-REx such a compelling mission, and our understanding of the cosmos is all the better for it.