Studying the Composition and Mineralogy of the Hermean Surface with the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) for the BepiColombo Mission: An Update

Abstract

Launched onboard the BepiColombo Mercury Planetary Orbiter (MPO) in October 2018, the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) is on its way to planet Mercury. MERTIS consists of a push-broom IR-spectrometer (TIS) and a radiometer (TIR), which operate in the wavelength regions of 7-14 μm and 7-40 μm, respectively. This wavelength region is characterized by several diagnostic spectral signatures: the Christiansen feature (CF), Reststrahlen bands (RB), and the Transparency feature (TF), which will allow us to identify and map rock-forming silicates, sulfides as well as other minerals. Thus, the instrument is particularly well-suited to study the mineralogy and composition of the hermean surface at a spatial resolution of about 500 m globally and better than 500 m for approximately 5-10% of the surface. The instrument is fully functional onboard the BepiColombo spacecraft and exceeds all requirements (e.g., mass, power, performance). To prepare for the science phase at Mercury, the team developed an innovative operations plan to maximize the scientific output while at the same time saving spacecraft resources (e.g., data downlink). The upcoming fly-bys will be excellent opportunities to further test and adapt our software and operational procedures. In summary, the team is undertaking action at multiple levels, including performing a comprehensive suite of spectroscopic measurements in our laboratories on relevant analog materials, performing extensive spectral modeling, examining space weathering effects, and modeling the thermal behavior of the hermean surface.

Science Goals and Mission Concept for a Landed Investigation of Mercury

“…Although MESSEN-GERʼs compositional data acquired from orbit called into question previous models of the planetʼs formation and evolution, only in situ geochemical measurements will enable us to test new hypotheses. BepiColombo is positioned to add to our compositional knowledge (Rothery et al 2020), in particular by improving coverage of elemental compositional measurements over the southern hemisphere and better characterizing silicate mineralogy using orbital thermal infrared imaging spectroscopy (e.g., Hiesinger et al 2020). Yet, direct in situ elemental and mineralogical measurements on Mer-curyʼs surface are essential to address the new science questions that have arisen since MESSENGER.…”

BepiColombo Science Investigations During Cruise and Flybys at the Earth, Venus and Mercury

“…5.2). MERTIS (Hiesinger et al 2020, this journal) will allow sensing the atmosphere from the top to an altitude of about 60 km above the surface, just within the upper cloud deck. It will also be able to detect mid-infrared thermal emissions from the cloud top level at daytime, and from below the cloud top at nighttime.…”

Mid‐Infrared Spectroscopy of Anorthosite Samples From Near Manicouagan Crater, Canada, as Analogue for Remote Sensing of Mercury and Other Terrestrial Solar System Objects

“…manuscript submitted to JGR Planets nels (Spectrometer Channels/TIS) and from 7 µm to 40 µm (1429 cm −1 to 250 cm −1 ) with 2 channels (Radiometer Channels/TIR) (Hiesinger et al, 2010;Hiesinger et al, 2020).…”

“…In October 2018, the BepiColombo spacecraft was launched to investigate Mercury. Onboard the spacecraft is the MErcury Radiometer and Thermal Infrared Spectrometer (MERTIS), which will explore Mercury's surface in the mid-IR (Hiesinger et al, 2010(Hiesinger et al, , 2020. The goals of MERTIS are studying and mapping the surface mineralogy as well as the thermal inertia (Hiesinger et al, 2010).…”

“…The goals of MERTIS are studying and mapping the surface mineralogy as well as the thermal inertia (Hiesinger et al, 2010). For this, MERTIS measures in the wavelength region from 7 to 14 μm (1,429 cm −1 to 714 cm −1 ) with 78 channels (Spectrometer Channels/TIS) and from 7 to 40 μm (1,429 cm −1 to 250 cm −1 ) with 2 channels (Radiometer Channels/TIR) (Hiesinger et al, 2010(Hiesinger et al, , 2020.…”