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
Go to topicThank you for liking
You have already liked this page, you can only like it once!
Artist's impression of the protosolar cloud, a mass of gas and dust that gave rise to the Sun and planets 4.6 billion years ago.
Observations of the noble gas xenon, performed by ESA's Rosetta mission at Comet 67P/Churyumov-Gerasimenko, revealed that the blend of isotopes found at the comet closely resembles U-xenon, the primordial mixture that scientists believe was brought to Earth during the early stages of Solar System formation. In contrast, the comet's blend of this gas is quite different from the mixture of xenon isotopes found in meteorites deriving from asteroids, and in the solar wind – the flow of charged particles streaming from the Sun.
These measurements suggest that comets contributed about one fifth the amount of xenon in Earth's ancient atmosphere. They also indicate that the protosolar cloud from which the Sun, planets, and small bodies were born was a rather inhomogeneous place in terms of its chemical composition.