Bennu’s Ancient Brine Sheds Light on Recipe for Life

The Science

NASA's OSIRIS-REx is the first U.S. mission to gather samples from Bennu, a carbon-rich asteroid. Although Bennu originated from an ancient, wet parent world, it now passes near Earth every six years. NASA gathered samples from Bennu to shed light on the origins of life and the solar system's history. One research team identified and determined the order in which salt minerals formed from brine (salty water) as it evaporated on Bennu's parent world. Another research group identified five nucleobases in the samples. (Nucleobases are the key building blocks of DNA and RNA for life on Earth.) This discovery would have been impossible without the preservation of pristine asteroid samples and the Department of Energy's (DOE) tools to analzye them. The researchers used the Molecular Foundry and the Advanced Light Source, both DOE Office of Science User Facilities hosted by DOE's Lawrence Berkeley National Laboratory.

The Impact

A briny environment offers favorable conditions for creating molecules that contain carbon. The findings from the Bennu samples support the idea that asteroids may have been a way to deliver water and essential chemical building blocks of life to Earth. Brines share features of icy dwarf planets and moons in our solar system. The results suggest that the potential ingredients and conditions for the origin of life could be widespread throughout the solar system.

Summary

NASA's OSIRIS-REx mission gathered the largest sample ever captured in space and returned to Earth from an extraterrestrial body beyond the Moon. Using the nearly 122 grams of material from Bennu, 40 institutions sought to investigate various components of the rocks. At the Molecular Foundry, experts used an ion beam to carve out microscopic sections of the Bennu samples. The samples were about a thousand times thinner than a sheet of paper. Researchers used the Advanced Light Source to probe the composition and chemistry of samples using non-destructive X-ray light. The results helped researchers determine the presence of specific chemical bonds at the nanometer scale. They also mapped out the different chemicals found in the asteroid. The results from Berkeley Lab and the contributing institutions clarified Bennu's chemical composition. These results will help everyone better understand how our solar system and planets evolved.

Contact

Scott SandfordNASA Ames Research [email protected]

Mathew MarcusAdvanced Light Source, Lawrence Berkeley National [email protected]

Funding

The research used resources at the Advanced Light Source and Molecular Foundry, both Department of Energy Office of Science user facilities.

Publications

McCoy, T. J., et al. "An evaporite sequence from ancient brine recorded in Bennu samples". Nature 637, 1072-1077 (2025). [https://doi.org/10.1038/s41586-024-08495-6]

Related Links

NASA's Asteroid Bennu Sample Reveals Mix of Life's Ingredients, NASA News

Bennu's Ancient Brine Sheds Light on Recipe for Life, Lawrence Berkeley Lab, Advanced Light Source

Berkeley Lab Helps Explore Mysteries of Asteroid Bennu, Berkeley Lab