¹Anna Zappatini et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70110]
¹Institute of Geological Sciences, University of Bern, Bern, Switzerland
Published by arrangement with John Wiley & Sons

A fireball camera system installed in 2022 by the Oman Meteorite MonitoringProject (OMMP) as part of the Global Fireball Observatory (GFO) recorded a 3.2 s fireballon March 8, 2022 at 8:15 p.m. UTC. A meteoroid of 4 2 kg entered the atmosphere at14.0 km/s. Its trajectory, with a slope of 68.4°, started at 67.6 km and ended at 30.2 kmwhere the meteoroid traveled at 7.36 km/s. Approximately 50 g survived atmospheric entry.On February 7, 2023, two meteorites of 13.85 g and 8.21 g were recovered at the predictedsite. Gamma spectrometry confirmed their young terrestrial age via short-lived cosmogenicradionuclides 54 Mn and 22 Na. Al-Khadhaf is thus the first camera-observed meteorite fallfrom Oman. Petrography and mineral composition classify it as an ordinary H5–6 S2 W1chondrite. Its pre-impact orbit (a = 1.72 AU, e = 0.45, i = 4.36°) is consistent withasteroid-belt delivery, with both inner-belt and Koronis-family sources remaining plausible.The cosmic ray exposure age of 8.57 1.2 Ma coincides with an exposure-age peak observedamong H chondrites. Al-Khadhaf adds to the record of camera-observed falls, linkingmeteorite compositions to their solar system context via orbit calculations.

¹Laura B. Seifert et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70093]
¹Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, Texas, USA
Published by arrangement with John Wiley & Sons

Calcium phosphates are ubiquitous in planetary materials, including samples returned from asteroid Bennu by the OSIRIS-REx mission. We characterized apatite [Ca5(PO4)3(F,Cl,OH)] grains in Bennu samples by scanning electron microscopy, electron microprobe analysis, and transmission electron microscopy to investigate their compositions, mineral associations, and microstructures. We find that Bennu apatite is halogen-poor, consistent with a composition of hydroxyapatite, and can be separated into two main structural types: single crystals, which often exhibit etched crystal faces, and anhedral polycrystalline assemblages. Both types exhibit zoning in cathodoluminescence imaging that results from incorporation of trace Mn2+ and rare earth elements into the apatite structure during crystal growth. Transmission electron microscopy of a single phosphate crystal and a polycrystalline assemblage reveals close association between apatite and phyllosilicates in the surrounding matrix. Phyllosilicates are either oriented parallel to intact apatite crystal facets or radiating from altered crystal faces. We interpret that single crystals with or without etched crystal faces are among the least aqueously altered of the observed apatites, whereas polycrystalline assemblages exhibiting a porous texture, consistent with successive dissolution–reprecipitation reactions, represent assemblages that experienced more extensive aqueous alteration. These microstructural data suggest that several stages of aqueous alteration likely occurred on Bennu’s parent body, leading to the mineral assemblages observed here.