NASA's Bennu Samples Reveal a 4.5-Billion-Year-Old Solar System Secret

A study now published in Science Advances, drawing on the roughly 120 grams of material NASA's OSIRIS-REx spacecraft returned from asteroid Bennu to Utah in 2023, has overturned previous assumptions about Bennu's origin. Researchers found that Bennu shares strikingly similar isotopic fingerprints with asteroid Ryugu and rare CI meteorites, indicating all three formed from the same ancient cosmic dust reservoir near the solar system's water-ice line — the boundary where temperatures fell cold enough for water to freeze. The team's leading hypothesis is that Jupiter, which coalesced within the first million years of the Sun's birth, acted as a gravitational barrier that kept larger particles from crossing its orbit while allowing fine dust from the inner and outer disk to mix freely in this transition zone. Lead researcher Maria Schönbächler, Professor of Isotope Geochemistry at ETH Zurich, noted that Bennu may offer humanity's best direct glimpse of the primordial chemical mix from which Earth's building blocks ultimately came, and its samples may carry clues to how the ingredients for life arrived on the young Earth.