The NOMAD (“Nadir and Occultation for MArs Discovery”) spectrometer suite on board the ExoMars Trace Gas Orbiter (TGO) has been designed to investigate the composition of Mars’ atmosphere, with a particular focus on trace gases, clouds and dust. The detection sensitivity for trace gases is considerably improved compared to previous Mars missions, compliant with the science objectives of the TGO mission. This will allow for a major leap in our knowledge and understanding of the Martian atmospheric composition and the related physical and chemical processes. The instrument is a combination of three spectrometers, covering a spectral range from the UV to the mid-IR, and can perform solar occultation, nadir and limb observations. In this paper, we present the science objectives of the instrument and explain the technical principles of the three spectrometers. We also discuss the expected performance of the instrument in terms of spatial and temporal coverage and detection sensitivity.

中文翻译：

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NOMAD，用于 ExoMars 痕量气体任务的三个光谱仪的集成套件：技术描述、科学目标和预期性能

ExoMars 微量气体轨道飞行器 (TGO) 上的 NOMAD（“火星发现的天底和掩星”）光谱仪套件旨在研究火星大气的成分，特别关注微量气体、云和灰尘。与之前的火星任务相比，微量气体的检测灵敏度得到了显着提高，符合 TGO 任务的科学目标。这将使我们对火星大气成分和相关物理和化学过程的认识和理解发生重大飞跃。该仪器是三台光谱仪的组合，覆盖了从紫外到中红外的光谱范围，可以进行太阳掩星、天底和边缘观测。在本文中，我们介绍了仪器的科学目标并解释了三种光谱仪的技术原理。我们还讨论了仪器在空间和时间覆盖范围和检测灵敏度方面的预期性能。