I.W. Iqbal¹, J.W. Head III^b, L. Wueller^a, H. Hiesinger^a, C.H. van der Bogert^a, D.R. Scott^b,c

Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116791]
^aInstitut für Planetologie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
^bDepartment of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA
^aApollo 15 Commander, USA
Copyright Elsevier

Eloy PENA-ASENSIO^1,2, Denis VIDA^3,4, Ingrid CNOSSEN⁵ , and Esteban FERRER²
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70046]
¹Department of Geosciences, University of Arizona Geosciences, Tucson, Arizona, USA
²School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
³Lawrence Livermore National Laboratory, Livermore, California, US
Published by arrangement with John Wiley & Sons

Climate change is inducing a global atmospheric contraction above the tropopause (~10 km), leading to systematic decrease in neutral air density. The impact of climate change on small meteoroids has already been observed over the last two decades, with documented shifts in their ablation altitudes in the mesosphere (~50–85 km) and lower thermosphere (~85–120 km). This study evaluates the potential effect of these changes on meteorite-dropping fireballs, which typically penetrate the stratosphere (~10–50 km). As a case study, we simulate the atmospheric entry of the fragile Winchcombe carbonaceous chondrite under projected atmospheric conditions for the year 2100 assuming a moderate future emission scenario. Using a semi-empirical fragmentation and ablation model, we compare the meteoroid’s light curve and deceleration under present and future atmospheric density profiles. The results indicate a modest variation of the ablation heights, with the catastrophic fragmentation occurring 300 m lower and the luminous flight terminating 190 m higher. The absolute magnitude peak remains unchanged, but the fireball would appear 0.5 dimmer above ~120 km. The surviving meteorite mass is reduced by only 0.1 g. Our findings indicate that century-scale variations in atmospheric density caused by climate change moderately influence bright fireballs and have a minimal impact on meteorite survival.

Isaiah SPRING¹, Ananya MALLIK¹, Jason KIRK¹, Pranabendu MOITRA¹, Richard HERVIG², and Lars BORG³
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70047]
¹Department of Geosciences, University of Arizona Geosciences, Tucson, Arizona, USA
²School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
³Lawrence Livermore National Laboratory, Livermore, California, US
Published by arrangement with John Wiley & Sons

We used trace element analyses of plagioclase from Mg-suite troctolite 76535 to estimate the Rare Earth Element (REE) concentrations of its parental liquid and assess the feasibility of an urKREEP contribution to the Mg-suite parental liquid. We measured 33 trace elements in 76535 plagioclase separates. Our measurements revealed enrichments in incompatible elements consistent with previous analyses. Using the measured REE concentrations, we estimated the REE concentrations of the unfractionated Mg-suite parental liquid using a RhyoliteMELTS-based forward model. Compared to chondritic concentrations, the Mg-suite parental liquid is ~100 times more enriched in light REEs and ~10 times more enriched in heavy REEs. We sought to explore the feasibility of reproducing these enrichments in the parental liquid through assimilation of urKREEP by a partial melt of rising LMO cumulates during cumulate mantle overturn. We show that these enrichments can be reproduced by a 30%–50% addition of fully molten urKREEP to the LMO cumulate melt, if the LMO cumulate melt and urKREEP are in thermal equilibrium with each other. However, the Mg# of these mixtures (57–68) is too low to produce the most Mg-rich olivine (Fo 91) observed in Mg-suite troctolites. Alternatively, assuming that the LMO cumulate melt and urKREEP are in thermal disequilibrium, we reproduced both the REE abundances and Mg# of the Mg-suite parental liquid with only a 10% addition of the urKREEP partial melt. These results support the feasibility of urKREEP assimilation as a mechanism for generating the incompatible element enrichments in Mg-suite magmas while preserving their major element chemistry.