
Scientists at ETH Zurich have published surprising findings from NASA’s OSIRIS-REx mission, which in 2023 delivered approximately 120 grams of material from asteroid Bennu to Earth. A 0.5-gram sample was allocated to Maria Schönbächler, a professor of isotope geochemistry, whose team analyzed isotopes of iron, titanium, and chromium to determine the asteroid’s origins.
The results, published in *Science Advances*, reveal that titanium and iron are evenly distributed across Bennu. The asteroid shares a near-identical isotopic fingerprint with asteroid Ryugu and CI chondrites, a rare class of carbon-rich meteorites found on Earth. This suggests all three formed from the same reservoir of cosmic dust, distinct from other known asteroids, meteorite groups, or planets.
The data contradict prior assumptions that Bennu formed in the outer solar system or late in its evolution. Instead, Schönbächler’s team proposes it originated near the water-ice line, where dust and ice mixed 4.5 billion years ago. “Bennu is a hybrid,” Schönbächler said, as its material does not fit neatly into either the inner or outer solar system categories .
Follow us for live European news
9 further sources not geolocated