The Mercury Radiometer and Thermal Infrared imaging Spectrometer (mertis) onboard Bepi Colombo: 2020 Moon flybys data results.

Abstract

The MErcury Radiometer and Thermal Infrared Spectrometer (MERTIS) is an instrument to study the mineralogy and temperature distribution of Mercury’s surface in unprecedented detail . During the nominal mission, MERTIS will map the whole surface at 500 m scale, combining a push-broom IR grating spectrometer (TIS) with a radiometer (TIR) sharing the same optics, instrument electronics, and in-flight calibration components for the whole wavelength range of 7-14um (TIS) and 7-40um (TIR) . MERTIS successfully completed its planned tests of the Near-Earth Commissioning Phase (NECP) in November 2018 and several checkouts, collecting thousands of measurements of its internal calibration bodies and deep space. Those data show a performance comparable with ground-based measurements. Scientific data will arrive well before the 2025 arrival at Mercury. MERTIS observed the Moon on in April 2020 producing ~12k TIS observation with ~3k measurements of the Moon at various angles. Even if the Moon is 7000 farther away and half maximum temperature than Mercury during nominal operation, the signal is clearly visible and shows the excellent MERTIS TIS sensor. MERTIS archival data are stored in Planetary Data System v4 format (PDS4) format, that actually describe 2 physical formats for each MERTIS channel. Each channel will be stored in Flexible Image Transport System (FITS) and in pure ASCII.