¹M. Eberhart,¹S. Loehle,²J. Vaubaillon,³P. Matlovič,³J. Tóth
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115868]
¹High Enthalpy Flow Diagnostics Group, Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart, Germany
²IMCCE, Observatoire de Paris, PSL, 77 Av. Denfert Rochereau, Paris, 75014, France
³Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
Copyright Elsevier

Experimental meteors are produced by exposing samples of meteoritic material to an air plasma flow in an arcjet driven plasma wind tunnel facility, simulating the aerothermal conditions of an entry into the Earth’s atmosphere. A plenoptic camera is used to record sequences of light field images during the tests, allowing for the first time to derive the transient evolution of the ablating and melting surface in three dimensions. Results are presented for samples of various meteorites, which show the potential of this technique for the volumetric analysis of the complex interaction between an extraterrestrial body and the upper atmosphere. Data allow to derive recession rates, heats of ablation and a shape factor, which has been redefined to meet the recorded information. Recession is found to be non-linear, with different rates for different meteorite types, with mean rates between 0.28 and 0.7 mm/s. Heats of ablation are not constant, but decrease during the experiment, with mean values between 1.7 and 10.1 MJ/kg. A fairly linear correlation is found between the materials’ iron content and both the recession rate and the heat of ablation. Shape factors decrease with time and reach a plateau after about 3 s.

¹Martin R. Lee,¹Lydia J. Hallis,^12,3Luke Daly,⁴Adrian J. Boyce
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14099]
¹School of Geographical & Earth Sciences, University of Glasgow, Glasgow, UK
²Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, New South Wales, Australia
³Department of Materials, University of Oxford, Oxford, UK
⁴Scottish Universities Environmental Research Centre, Glasgow, UK
Published by arrangement with John Wiley & Sons

CM carbonaceous chondrites can be used to constrain the abundance and H isotopic composition of water and OH in C-complex asteroids. Previous measurements of the water/OH content of the CMs are at the higher end of the compositional range of asteroids as determined by remote sensing. One possible explanation is that the indigenous water/OH content of meteorites has been overestimated due to contamination during their time on Earth. Here we have sought to better understand the magnitude and rate of terrestrial contamination through quantifying the concentration and H isotopic composition of telluric and indigenous water in CM falls by stepwise pyrolysis. These measurements have been integrated with published pyrolysis data from CM falls and finds. Once exposed to Earth’s atmosphere CM falls are contaminated rapidly, with some acquiring weight percent concentrations of water within days. The amount of water added does not progressively increase with time because CM falls have a similar range of adsorbed water contents to finds. Instead, the petrologic types of CMs strongly influence the amount of terrestrial water that they can acquire. This relationship is probably controlled by mineralogical and/or petrophysical properties of the meteorites that affect their hygroscopicity. Irrespective of the quantity of water that a sample adsorbs or its terrestrial age, there is minimal exchange of H in indigenous phyllosilicates with the terrestrial environment. The falls and finds discussed here contain 1.9–10.5 wt% indigenous water (average 7.0 wt%) that is consistent with recent measurements of C-complex asteroids including Bennu.