Calcium pyroxenes at Mercurian surface temperatures: investigation of in-situ emissivity spectra and thermal expansion.

摘要: The European Space Agency and Japan Aerospace mission to Mercury, named BepiColombo, will carry on board the Mercury Radiometer Thermal Infrared Spectrometer (MERTIS) that be able provide surface Infra-Red (TIR) emissivity spectra from 7 14 µm. This range of wavelengths is very useful identify fine-scale structural properties several silicates. For mineral families as pyroxenes, peak positions are good indicators composition. A complication in interpretation MERTIS data could arise extreme daily temperature (70 725 K) significantly affects crystal structure density minerals consequently should affect TIR spectral signature each single present planet. In preparation for analysis, we extensively investigating at high temperatures conditions phases potentially detectable Mercury. Two C2/c augitic with constant calcium content different magnesium iron ratio, were studied by situ high-temperature thermal infrared spectroscopy (up 750 single-crystal X-ray diffraction 770 K). The two samples show similar band center shifts main three bands toward lower wavenumbers increasing temperature. Our results indicate position 1 2 strictly dependent temperature, whereas 3 a strong function composition regardless temperature. These suggest indications pyroxene contents allow correct independently acquisition