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 CELIAS instrument aboard ESA's Soho satellite is studying the composition of the solar wind and of the solar and interplanetary accelerated energetic particles. It consists of three different sensors with associated electronics, each optimised each for a particular aspect of ion composition. These aspects are the elemental, isotopic and ionic charge composition of solar wind or energetic ions emanating from the Sun. In addition, CELIAS included the Solar EUV Monitor (SEM) for monitoring the absolute Extreme Ultra-Violet (EUV) flux from the Sun. [Image Date: 1997-09-00] [97.09.014-001]