Thermal decomposition of MgCO3during the atmospheric entry of micrometeoroids
| Autor: | Savino Longo, G. Micca Longo |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010504 meteorology & atmospheric sciences
Physics and Astronomy (miscellaneous) business.industry Magnesium Thermal decomposition Mineralogy chemistry.chemical_element Atmospheric sciences 01 natural sciences Decomposition Silicate chemistry.chemical_compound chemistry Space and Planetary Science Atmospheric entry 0103 physical sciences Thermal Earth and Planetary Sciences (miscellaneous) Carbonate business 010303 astronomy & astrophysics Ecology Evolution Behavior and Systematics Thermal energy 0105 earth and related environmental sciences |
| Zdroj: | International Journal of Astrobiology. 16:368-378 |
| ISSN: | 1475-3006 1473-5504 |
| DOI: | 10.1017/s1473550416000495 |
| Popis: | In this paper, a first study of the atmospheric entry of carbonate micrometeoroids, in an astrobiological perspective, is performed. Therefore an entry model, which includes two-dimensional dynamics, non-isothermal atmosphere, ablation and radiation losses, is build and benchmarked to literature data for silicate micrometeoroids. A thermal decomposition model of initially pure magnesium carbonate is proposed, and it includes thermal energy, mass loss and the effect of changing composition as the carbonate grain is gradually converted into oxide. Several scenarios are obtained by changing the initial speed, entry angle and grain diameter, producing a systematic comparison of silicate and carbonate grain. The results of the composite model show that the thermal behaviour of magnesium carbonate is markedly different from that of the corresponding silicate, much lower equilibration temperatures being reached in the first stages of the entry. At the same time, the model shows that the limit of a thermal protection scenario, based on magnesium carbonate, is the very high decomposition speed even at moderate temperatures, which results in the total loss of carbon already at about 100 km altitude. The present results show that, although decomposition and associated cooling are important effects in the entry process of carbonate grains, the specific scenario of pure MgCO3micrograin does not allow complex organic matter delivery to the lower atmosphere. This suggests us to consider less volatile carbonates for further studies. |
| Databáze: | OpenAIRE |
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