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!
This animation shows the Gaia spacecraft spinning in space scanning the sky.
Gaia’s mission relies on the systematic and repeating observation of star positions in two fields of view. As the detectors repeatedly measure the position of each celestial object, they will detect any changes in the object’s motion through space.
To achieve its mission the spacecraft is spinning slowly, sweeping its two telescopes across the entire celestial sphere to make four complete rotations per day.
Gaia’s telescopes point at two different portions of the sky, separated by a constant 106.5°. Therefore, objects arrive in the second field of view 106.5 minutes after they are observed in the first.
Meanwhile its spin axis precesses around the Sun with a period of about 63 days, allowing different parts of the sky to be scanned. This scanning strategy builds up an interlocking grid of positions, providing absolute – rather than relative – values of the stellar positions and motions.
The spacecraft spin axis makes an angle of 45° with the Sun direction, ensuring that the payload is shaded from the Sun, but that the solar arrays can still produce electricity efficiently.