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Full list of authors: Enya, Keigo; Kobayashi, Masanori; Kimura, Jun; Araki, Hiroshi; Namiki, Noriyuki; Noda, Hirotomo; Kashima, Shingo; Oshigami, Shoko; Ishibashi, Ko; Yamawaki, T.; Tohara, Kazuyuki; Saito, Yoshifumi; Ozaki, Masanobu; Mizuno, Takahide; Kamata, Shunichi; Matsumoto, Koji; Sasaki, Sho; Kuramoto, Kiyoshi; Sato, Yuki; Yokozawa, Takeshi; Numata, Tsutomu; Mizumoto, Satoko; Mizuno, Hiroyuki; Nagamine, Kenta; Sawamura, Akihiko; Tanimoto, Kazuo; Imai, Hisato; Nakagawa, Hiroyuki; Kirino, Okiharu; Green, David; Fujii, Masayuki; Iwamura, Satoru; Fujishiro, Naofumi; Matsumoto, Yoshiaki; Lingenauber, Kay; Kallenbach, Reinald; Althaus, Christian; Behnke, Thomas; Binger, Jan; Daurskikh, Anna; Eisenmenger, Henri; Heer, Ulrich; Hüttig, Christian; Lara, Luisa M.; Lichopoj, Alexander; Lötzke, Horst-Georg; Lüdicke, Fabian; Michaelis, Harald; Pablo Rodriguez Garcia, Juan; Rösner, Kerstin; Stark, Alexander; Steinbrügge, Gregor; Thabaut, Pascal; Thomas, Nicolas; del Togno, Simone; Wahl, Daniel; Wendler, Belinda; Wickhusen, Kai; Willner, Konrad; Hussmann, Hauke.--This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/)., The Jupiter Icy Moons Explorer (JUICE) is a science mission led by the European Space Agency, being developed for launch in 2023. The Ganymede Laser Altimeter (GALA) is an instrument onboard JUICE, whose main scientific goals are to understand ice tectonics based on topographic data, the subsurface structure by measuring tidal response, and small-scale roughness and albedo of the surface. In addition, from the perspective of astrobiology, it is imperative to study the subsurface ocean scientifically. The development of GALA has proceeded through an international collaboration between Germany (the lead), Japan, Switzerland, and Spain. Within this framework, the Japanese team (GALA-J) is responsible for developing three receiver modules: the Backend Optics (BEO), the Focal Plane Assembly (FPA), and the Analog Electronics Module (AEM). Like the German team, GALA-J also developed software to simulate the performance of the entire GALA system (performance model). In July 2020, the Proto-Flight Models of BEO, FPA, and AEM were delivered from Japan to Germany. This paper presents an overview of JUICE/GALA and its scientific objectives and describes the instrumentation, mainly focusing on Japan's contribution. © 2021 COSPAR., NSO/Kitt Peak data (synoptic maps of He I Å intensity) used here are produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL. Sunspot number (version 2) comes from the Sunspot Index and Long-term Solar Observations at Royal Observatory of Belgium, Brussels. All used data are courtesy to be downloaded from their web sites. The authors would like to express their deep thanks to the staffs of these web sites. This work is supported by the National Natural Science Foundation of China (11973085, 11903077, 11803086, and 11633008), the Yunnan Ten-Thousand Talents Plan (the Yunling-Scholar Project), the national project for large scale scientific facilities (2019YFA0405001), and the Chinese Academy of Sciences., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

At DLR we have developed a spectral and radiometric calibration target that will allow a cross calibration of the MARA and the TIR instrument. We use a serpentinite rock sample, which in the thermal infrared shows a strong spectral slope as well as well defined spectral feature. Obtaining measurements of this target with both instruments will greatly facilitate the correlation of orbital measurements obtained by the TIR with in-situ measurements by MARA. The calibration target is portable and highly adaptable, which will allow use for future mission.

Radiative heat transfer plays a major role in the thermal behavior of any space application compared to a typical Earth-based system. Space systems are known to operate in an environment characterized by a wide range of temperatures and heat loads, such as planetary and solar fluxes or deep space, planet and sun temperature. All these factors will critically impact upon the thermal design of spacecraft and special thermal coatings are generally used in thermal control. Many of these coatings present temperature dependent thermo-optical properties, which cannot be neglected in the design of space systems. However, in most thermal models, the temperature dependence is often reduced to the definition of two sets of properties, namely the IR and UV ranges. In addition, space systems usually present complex 3D geometries like antennas, optical devices or reflective baffles. For such components, the thermal behaviour is generally strongly coupled to their geometry, for instance the amount of rejected environmental radiation of a reflective baffle depends upon the shape of its reflective surfaces. It is therefore essential to model their surfaces with high accuracy. Unfortunately, complex shapes are often not fully implemented in thermal software. The objective of this paper is to present a general method to implement temperature dependant thermo-optical properties and to approximate complex 3D geometry using ESATAN-TMS, the European standard thermal analysis package. Practical applications for current space missions will be used to illustrate both methods and a comparison between different models will be presented to show the high inaccuracy that occurs when temperature dependencies are neglected.

In the frame of the ESA BepiColombo mission to the planet Mercury the German Aerospace Center (DLR), in cooperation with the University of Bern, is designing the first European laser altimeter for planetary exploration (BELA). While orbiting Mercury the solar flux reaches 14 kW and strikes on the instrument at angles of > 38 deg from the instrument line of sight. The planet surface reaches 700 K while the view factor with the instrument aperture is high due to the low orbit altitude. Under these conditions a major challenge is the design of the instrument baffles, which shall avoid direct sunlight to reach the optics, minimize the heat load to the instrument and the S/C cavity and reduce stray light. We describe the thermal model of the transmitter baffle, focusing on advanced features like the approximation of ellipsoids and hyperboloids in the geometrical mathematical model, its optimization with respect to computational time and baffle efficiency, the dynamic implementation of wavelength dependant thermo- optical properties for the calculation of both absorbed planetary fluxes – as function of Mercury surface temperature – and radiative conductances (GR). The worst cases selection in the scenario of the whole Mercury orbit about the sun is also presented followed by a detailed overview of the analysis results.