Airglow and Aurora in the Martian Atmosphere: Contributions by the Mars Express and ExoMars TGO Missions

The study of atmospheric emissions from orbit to probe the middle and upper atmosphere of Mars, which started with the Mariner missions, is living a golden era thanks to the European Space Agency (ESA) Mars Express mission and other subsequent missions built upon its success, including the ESA ExoMars Trace Gas Orbiter (TGO) mission. Here we summarize the most relevant information obtained by the analysis of atmospheric emissions data from Mars Express and TGO, about the temperature and density structure, the atmospheric dynamics, the chemistry and the atmospheric escape to space. Mars Express also opened a new field of research on Mars with the discovery of aurorae on the planet. We present here the most outstanding results collected by Mars Express about aurorae. Finally, we also discuss how later measurements by other missions have complemented Mars Express and TGO results, and the potential future developments relevant to this field of research.