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 topicEarth-observing satellites travel in low-Earth orbit (LEO) gathering data and making a full circuit of Earth about every 100 minutes. They must wait to be over their respective ground stations to downlink the information they have acquired, however. Generally, this leaves only 10 minutes out of every 100 to transfer their information to the users on the ground. Any data gathered between these windows must be stored until the next downlink opportunity.
The European Data Relay System solves the downlink delay by connecting to the LEO satellites as they orbit past. EDRS collects the LEO data from its higher position in GEO and relays it down to its European ground stations, avoiding the time delay that occurs when the LEO satellite has to wait for ‘line of sight’ with its ground station. In fact, just one of the EDRS nodes can quadruple the Earth observer’s contact time with its ground segment.