Bennu Samples Trace Outer Solar System Origins and Water Chemistry

A fresh batch of analyses from the Bennu samples collected by NASA’s OSIRIS-REx mission paints a detailed picture of the early solar system, revealing a complex lineage for the asteroid and offering a clearer view of how the cosmos took shape more than 4.5 billion years ago. The findings show Bennu’s material is a mosaic: presolar stardust, organic matter from interstellar space, high-temperature minerals formed near the young Sun, and a substantial record of chemical processing driven by water and space weathering. Taken together, the studies suggest Bennu is made from fragments of a much larger parent body that formed in a distant region of the solar system, was shattered by an impact, and later reassembled into the object we see today.

Researchers conclude Bennu’s parent asteroid formed in the outer reaches of the solar system, possibly beyond the giant planets, with fragments that carried materials from across the solar neighborhood and beyond. Isotopic analyses show a mix of solar-system-origin substances, presolar grains, and interstellar material, indicating that the original building blocks traveled long distances before coming together. The parent body likely formed...