¹Patrick M. Shober et al. (>10)
Meteoritics & Plantetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13813]
¹Space Science & Technology Centre, School of Earth and Planetary Sciences, Curtin University, Bentley, Western Australia, 6102 Australia
Published by arrangement with John Wiley & Sons

On June 1, 2019, just before 7:30 p.m. local time, the Desert Fireball Network (DFN) detected a −9.3 magnitude fireball over South Australia near the Western Australia border. The event was observed by six fireball observatories, and lasted for 5 s. One station was nearly directly underneath the trajectory, greatly constraining the trajectory solution. This trajectory’s backward numerical integrations indicate that the object originated from the outer main belt with a semimajor axis of 2.75 au. A light curve was also extracted and showed that the body experienced very little fragmentation during its atmospheric passage. A search campaign was conducted with several DFN team members and other volunteers. One 42 g fragment was recovered within the predicted fall area based on the dark flight model. Based on measurements of short-lived radionuclides, the fragment was confirmed to be a fresh fall. The meteorite, Arpu Kuilpu, has been classified as an H5 ordinary chondrite. This marks the fifth fall recovered in Australia by the DFN, and the smallest meteoroid (≃2 kg) to ever survive entry and be recovered as a meteorite.

¹Chelsea D.Willett,¹William S.Cassata,¹Naomi E.Marks
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.04.017]
¹Nuclear and Chemical Science Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
Copyright Elsevier

Novel analytical approaches to determining the trapped 38Ar/36Ar ratio of gases contained within Martian meteorites are presented and applied to the Martian regolith breccia Northwest Africa (NWA) 7034 and paired stone NWA 11220. The resulting data indicate that extensive mass-dependent fractionation of atmospheric Ar may have occurred within 150 million years of planetary formation, ostensibly as a result of diffusion-limited hydrodynamic escape. The inferred fractional loss of Ar and lighter atmospheric constituents exceeds 50%. These data suggest that volatiles derived from planetary outgassing and/or impactors may dominate the present abundance of atmospheric Ar.