Evaluating new spectral analysis techniques to study the hot surface of Mercury with MERTIS on BepiColombo

Abstract

Mercury is the closest planet to the Sun and its formation still remains unclear. It is an important boundary condition for formation models of our solar system and planetary system in general. Among the exoplanets many planets have been discovered in similar distances from their host star. Due to the closeness to the Sun Mercury experiences extreme temperature variations (-150degC – 450degC) during its day-night cycles. Spectroscopy is one of the most powerful techniques to study the surface mineralogy of any planetary body from its orbit. Various spectral ranges provide different insights to the surface we look at. In order to spectrally interpret the surface mineralogy, it is important to understand the spectral behavior of the planet’s analogues under its respective surface environment conditions in a controlled laboratory setup. This thesis focuses primarily on understanding the composition of Mercury from orbital remote sensing observations, especially with the Mercury Radiometer and Thermal Imaging Spectrometer (MERTIS) instrument onboard ESA-JAXA BepiColombo mission to Mercury. MERTIS will be the first radiometer and the first thermal infrared (TIR; 7-14 μm) hyperspectral spectrometer to orbit Mercury. To this purpose a specialized spectral library was created of various Mercury analogues under their extreme environmental conditions as a function of temperature under vacuum, the stability and spectral signature of a range of sulfides was studied, the derivation of various spectral parameters to facilitate the mapping of surface composition was evaluated and with these the analysis of data in the visible and near-infrared by the NASA MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) was revisited.