Abstract
Abstract Meteoroids largely disintegrate during their entry into the atmosphere, contributing significantly to the input of cosmic material to Earth. Yet, their atmospheric entry is not well understood. Experimental studies on meteoroid material degradation in high-enthalpy facilities are scarce and when the material is recovered after testing, it rarely provides sufficient quantitative data for the validation of simulation tools. In this work, we investigate the thermo-chemical degradation mechanism of a meteorite in a high-enthalpy ground facility able to reproduce atmospheric entry conditions. A testing methodology involving measurement techniques previously used for the characterization of thermal protection systems for spacecraft is adapted for the investigation of ablation of alkali basalt (employed here as meteorite analog) and ordinary chondrite samples. Both materials are exposed to a cold-wall stagnation point heat flux of 1.2 MW m−2. Numerous local pockets that formed on the surface of the samples by the emergence of gas bubbles reveal the frothing phenomenon characteristic of material degradation. Time-resolved optical emission spectroscopy data of ablated species allow us to identify the main radiating atoms and ions of potassium, calcium, magnesium, and iron. Surface temperature measurements provide maximum values of 2280 K for the basalt and 2360 K for the chondrite samples. We also develop a material response model by solving the heat conduction equation and accounting for evaporation and oxidation reaction processes in a 1D Cartesian domain. The simulation results are in good agreement with the data collected during the experiments, highlighting the importance of iron oxidation to the material degradation.
Highlights
Meteoroids provide our primary source of extraterrestrial materials from the various nebular and planetary environments of the solar system and beyond
These naturally delivered samples, bringing in 50–100 tons of material every day (Flynn 2002), undergo melting and evaporation during their entry into the Earth’s atmosphere. This results in variable levels of modification that need to be distinguished from pre-entry features in order to understand processes occurring during transport in open space, residence in or on their parent body, and their original formation during the earliest history of the solar system
Not further detailed in this paper, the sample was first dried at 120 °C for two hours to remove any possible water contamination and was held in a cork holder with a gap between the lateral side of the sample to release any mechanical stress on the basalt sample from an expansion of the cork
Summary
Meteoroids provide our primary source of extraterrestrial materials from the various nebular and planetary environments of the solar system and beyond These naturally delivered samples, bringing in 50–100 tons of material every day (Flynn 2002), undergo melting and evaporation during their entry into the Earth’s atmosphere. This results in variable levels of modification that need to be distinguished from pre-entry features in order to understand processes occurring during transport in open space, residence in or on their parent body, and their original formation during the earliest history of the solar system.
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