Astromat

Here, we report the mass-independent Ti isotope composition of the Bennu quick-look sample OREX-501018-100. We also present data for the terrestrial standard BHVO-2 and the CM2 chondrite Aguas Zarcas, which were used to monitor data quality. Mass-independent isotope analyses were carried out at ETH Zurich (Switzerland) using a Neptune Plus MC-ICP-MS. The composition of Bennu is 0.26 ± 0.18 (±2SE; n=4), 0.03 ± 0.07 and 1.94 ± 0.16 for ε46Ti/47Ti, ε48Ti/47Ti and ε50Ti/47Ti, respectively. The Ti isotope data of Bennu overlaps with that of CI chondrites and Ryugu. Therefore, the composition of Bennu closely resembles our best estimate of the initial composition of the solar system. This confirms the mission hypothesis that Bennu formed in the carbonaceous reservoir, which consists of material that originated beyond the snowline.