Infrarot-Spektralanalysen an Merkur- Analogmaterialien

Abstract

The planet Mercury has been poorly explored due to its position relative to the sun and its extreme environmental conditions. The BepiColombo mission, a collaboration between ESA and JAXA, aims to change this. The infrared instrument MERTIS, which provides spectral data from Mercury’s surface, plays a key role in this mission. Real Mercury samples are not available. Therefore, so-called analogs are used. These are terrestrial rock samples whose composition is comparable to that of Mercury’s surface. The goal of this work is to provide spectral reference data for comparing and interpreting the MERTIS measurements. To achieve this, selected analog samples were spectroscopically analyzed in the UV, visible, near-infrared, and mid-infrared ranges under vacuum conditions at the Planetary Spectroscopy Laboratory of the German Aerospace Center in Berlin Adlershof. The focus was on identifying spectral signatures of mineral mixtures with varying grain sizes of the analog materials. The results show that even small amounts of graphite darken the overall spectrum. Sulfides, in contrast, only exhibit a significant influence on the overall spectrum at higher concentrations. For diopside and oligoclase, the smaller grain sizes lead to higher reflectance. The results are fundamental for the accurate calibration and interpretation of MERTIS data. This work contributes to a better understanding of the mineralogical composition of Mercury’s surface and provides direct support for the evaluation of the recent Mercury flyby of BepiColombo.