Europe's Gaia satellite to map a billion stars
21 August 2013 Last updated at 11:17 BST
The European Space Agency plans to launch its Gaia surveyor mission towards the end of this year.
The satellite will map the positions on the sky of a billion stars, providing new insights on the history of our Milky Way galaxy.
Gaia, which carries the largest camera ever built to go into space, should also discover thousands of new planets, asteroids and comets.
This video shows how Gaia will unfurl the shield that will protect its careful measurements from the glare of the Sun.