Status of the Mercury Thermal Radiometer and Thermal Infrared Spectrometer (MERTIS) for BepiColombo

Abstract

The Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) is an innovative instrument for studying the surface composition and mineralogy of planet Mercury. In particular, the scientific objectives of MERTIS include 1.) Study of Mercury’s surface composition, 2.) Identification of rock-forming minerals, 3.) Mapping of the surface mineralogy, and 4.) Study of surface temperature variations and the thermal inertia. The instrument combines an uncooled grating push-broom IR-spectrometer (TIS) with a radiometer (TIR), which will operate in the wavelength region of 7-14 um and 7-40 um, respectively [1,2]. The thermal infrared range offers unique diagnostic capabilities to study the surface composition of Mercury. For example, feldspars can easily be detected and characterized, because they show several diagnostic spectral signatures in the 7-14 um range: the Christiansen feature, reststrahlen bands, and the transparency feature. In addition, MERTIS will allow identifying and mapping of elemental sulfur, pyroxenes, olivines, and other complex minerals. Scheduled for launch on-board the BepiColombo Mercury Planetary Orbiter (MPO) in 2016, MERTIS will arrive at Mercury in 2024. From its nominal orbit, MERTIS will map the surface globally at a spatial resolution of about 500 m and for approximately 5-10% of the surface at a resolution of up to 280 m