The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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The ESA-Roscosmos ExoMars Trace Gas Orbiter is investigating the martian atmosphere. Discovering new gases related to active process and looking for their sources is a key goal of the mission. ExoMars has discovered hydrogen chloride for the first time. It appeared during a global dust storm in 2018 and disappeared again afterwards. The detection was made in both hemispheres simultaneously so it is unlikely to come from volcanic activity. Seasonal change that triggers dust activity is thought to be the driving force behind the observation. Salt in the dusty surface – left over from when Mars had water on its surface earlier in its history – reacts with water vapour in the atmosphere to release chlorine. The chlorine and hydrogen react to create hydrogen chloride gas. The discovery of this new type of gas requires a change in understanding of Mars’ global atmospheric chemistry and processes.