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 plasma package called the Analyser of Space Plasmas and Energetic Atoms (ASPERA-4) on board ESA’s Venus Express has established, for the
first time, the composition of escaping plasma on Venus.
Venus loses mainly oxygen, hydrogen, and helium via its atmosphere’s interaction with the solar wind. The hydrogen that escapes, originates from
the small amounts of water present in the atmosphere. Water molecules in the atmosphere, or water vapour, break down under the action of the Sun’s
ultraviolet radiation to produce one oxygen atom and two hydrogen atoms. Solar ultraviolet light ionises the atoms that are then picked up by the
solar wind and accelerated. They eventually escape the planet. Oxygen can also originate from breaking carbon dioxide molecules.