Cometary analogue material: Preparation, composition, and thin section petrography

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Abstract

Cometary analogue material has been synthesized in kilogram quantities by spraying suspensions of silicate mineral dust with a median grain size of 4–8 μm, and carbon (soot of −25 nm grain size) into liquid nitrogen under controlled conditions. The samples with densities between 0.3 and 0.7 g/cm3 were used for sublimation experiments and for uniaxial compression tests. In one case fragments of consolidated phionolitic tuff (0.6–2.5 and 2.5–10 mm size fractions) were admixed mechanically. By modifying existing techniques polished sections and thin sections were produced from these samples for optical microscopy. Changes in the intergrowth characteristics, the grain size of the ice crystals, and the porosity were observed in the irradiated and compressed samples. They are due to sublimation-condensation-recrystallization and compaction-recrystallization effects, respectively.

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