Comprehensive high-energy SXRF analyses of Ca-rich phases of the two main lithologies found on asteroid Bennu

We will apply high-energy synchrotron X-ray fluorescence (SXRF) spectroscopy (90 keV) at beamline ID15A on samples collected on asteroid Bennu and brought back to Earth during NASA’s OSIRIS-Rex space mission. Thin sections (30 µm thick) of two main groups of Bennu rock fragments, the angular type and the hummocky type, will be sent by NASA to many laboratories for analysis applying many different techniques. As the only team selected by NASA to perform SXRF analysis on these two lithologies, we have the unique opportunity to measure the trace element content, especially rare-earth elements (REEs), in Ca-rich minerals (e.g. Ca-phosphates and carbonates) for direct comparison of the two main rock types found on the surface of asteroid Bennu. Our SXRF results of REE enrichments in these rocks will help to better understand the aqueous alteration and geological history of Bennu and provide unique insight into the role of fluids in such ancient asteroids from the early Solar System years.