On-ground calibration and performance evaluation of the Martian moons eXploration (MMX) infrared spectrometer (MIRS) for the Japan Aerospace Exploration Agency (JAXA) MMX mission. II. Data analyses and results of the on-ground calibration campaign.

The Martian Moons eXploration (MMX) mission of the Japan Aerospace Exploration Agency is equipped with different cameras and one spectrometer [K. Kuramoto et al., Earth, Planets Space 74, 12 (2022)] called the MMX InfraRed Spectrometer (MIRS). The instrument is devoted to investigate the origin of the Martian moons, Phobos and Deimos, as well as the Martian atmosphere and surface [M.A. Barucci et al., Earth, Planets Space 73, 211 (2021) and M. A. Barucci et al., Prog. Earth Planet. Sci. 12, 69 (2025)]. It is designed to identify spectral features attributed to ice, dust, water vapor, minerals and organics, all detectable within the [0.9-3.6] μm wavelength range of the instrument. MIRS itself is composed of different parts, namely, the electronic box and the OBOX (optical box), which are both linked by an electronic harness. This paper presents the second part of the MIRS calibration. The first paper [G. Poggiali et al., Rev. Sci. Instrum. 97, 054501 (2026)] aimed to explain the calibration plan, present the materiel and the list of measurements performed, and demonstrate MIRS' compliance with the scientific and technical objectives. This paper details the methodology used to extract the spectral registration, correct data from distortion, verify the radiometric curve against the theoretical optical one and enhance it, and extract the pixel-to-pixel response of the instrument. Effect of the OBOX temperature and the scanner orientation will also be discussed as the current caveats, which will be addressed using inflight calibration during the cruise and the main phases of the MMX mission.