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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A schematic of atmospheric profiling by GPS radio occultation. An occultation occurs whenever a GPS satellite rises or sets on the Earth limbs as seen from the Low Earth orbit (LEO) satellite. The GPS signal is refracted and slowed as it traverses the Earth’s atmospheric limb. This causes a phase delay that relates to characteristics of the Earth's atmosphere.