Euclid mission to probe dark cosmos
Europe has given the final go-ahead to a space mission to investigate the "dark universe".
The Euclid telescope, external will look deep into the cosmos for clues to the nature of dark matter and dark energy.
These phenomena dominate the Universe, and yet scientists concede they know virtually nothing about them.
Prof Bob Nichol, who is part of the Euclid Consortium, told our correspondent Jonathan Amos about the aims of the mission.