The MAJIS (Moons And Jupiter Imaging Spectrometer) instrument on board the ESA JUICE (JUpiter ICy moon Explorer) mission is an imaging spectrometer operating in the visible and near-infrared spectral range from 0.50 to 5.55 μm in two spectral channels with a boundary at 2.3 μm and spectral samplings for the VISNIR and IR channels better than 4 nm/band and 7 nm/band, respectively. The IFOV is 150 μrad over a total of 400 pixels. As already amply demonstrated by the past and present operative planetary space missions, an imaging spectrometer of this type can span a wide range of scientific objectives, from the surface through the atmosphere and exosphere. MAJIS is then perfectly suitable for a comprehensive study of the icy satellites, with particular emphasis on Ganymede, the Jupiter atmosphere, including its aurorae and the spectral characterization of the whole Jupiter system, including the ring system, small inner moons, and targets of opportunity whenever feasible. The accurate measurement of radiance from the different targets, in some case particularly faint due to strong absorption features, requires a very sensitive cryogenic instrument operating in a severe radiation environment. In this respect MAJIS is the state-of-the-art imaging spectrometer devoted to these objectives in the outer Solar System and its passive cooling system without cryocoolers makes it potentially robust for a long-life mission as JUICE is. In this paper we report the scientific objectives, discuss the design of the instrument including its complex on-board pipeline, highlight the achieved performance, and address the observation plan with the relevant instrument modes.

ESA JUICE（木星 ICy 月球探测器）任务中搭载的 MAJIS（卫星和木星成像光谱仪）仪器是一种成像光谱仪，在 0.50 至 5.55 μm 的可见光和近红外光谱范围内工作，在两个光谱通道中运行，边界为 2.3 VISNIR 和 IR 通道的 μm 和光谱采样分别优于 4 nm/波段和 7 nm/波段。IFOV 为 150 μrad，总共 400 个像素。正如过去和现在执行的行星空间任务已经充分证明的那样，这种类型的成像光谱仪可以跨越从表面到大气层和外逸层的广泛科学目标。MAJIS 非常适合对冰卫星进行全面研究，特别是木卫三、木星大气层，包括极光和整个木星系统的光谱特征，包括环系统、小型内卫星和机会目标只要可行。准确测量来自不同目标的辐射（在某些情况下由于强吸收特性而特别微弱）需要在恶劣辐射环境下运行的非常灵敏的低温仪器。在这方面，MAJIS 是最先进的成像光谱仪，专门用于外太阳系的这些目标，其无制冷器的被动冷却系统使其具有像 JUICE 一样稳健的长寿命任务的潜力。在本文中，我们报告了科学目标，讨论了仪器的设计，包括其复杂的机载管道，强调了所实现的性能，并利用相关仪器模式制定了观测计划。