Sulfides Versus Sulfur Mixes: Spectra in Wavelengths Relevant to BepiColombo's MERTIS and MIXS

Kurzfassung

In preparation for the BepiColombo mission to Mercury, we are investigating the ability for the onboard instruments to differentiate between sulfur and sulfides through reflectance and emission spectra measurements. Sulfur has been detected previously on Mercury’s surface and the data from BepiColombo will hopefully elucidate on the mineralogical phase it exists in [1]. The Mercury Imaging X-ray Spectrometer (MIXS) will observe the first 10-20 μm of Mercury’s surface and gather data regarding elemental compositions [2]. The Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) will observe Mercury’s surface in wavelengths of 7-14 μm with its IR-Spectrometer [3]. This instrument operates at these wavelengths to understand the mineralogy of the surface and is perfect for detecting sulfides on the surface [3]. Spectra were collected at the Deutsches Zentrum für Luft- und Raumfahrt in the Planetary Spectroscopy Laboratory (PSL) for the individual elements Ca, Mg, Fe and S as well as mixtures and the corresponding sulfides [3,4]. By creating mixes at the same weight percentages as the sulfides, we explore any impacts the molecular structure of these elements has on emission and reflectance spectra. We aim to observe any spectral features present due to the molecular structure of sulfides that would not be present in the elements alone and observe them in wavelengths relevant to the two instruments; this will display the ability for BepiColombo’s instruments to properly distinguish between elemental sulfur, even when mixed with other elements, and sulfides.