Euclid is an ESA medium class space mission (M2 slot), selected in October 2011 and with its launch planned for 2020. The Euclid mission aims at understanding why the expansion of the Universe is accelerating and the cause for this acceleration which physicists refer to as dark energy. Euclid will explore how the Universe evolved over the past 10 billion years to address questions related to fundamental physics and cosmology on the nature and properties of dark energy, dark matter and gravity. Euclid will also provide insightful information on the physics of the early universe and on the initial conditions which seed the formation of cosmic structure.
The imprints of dark energy and gravity will be tracked by using two complementary cosmological probes to capture signatures of the expansion rate of the Universe and the growth of cosmic structures: Weak gravitational Lensing and Galaxy Clustering (Baryonic Acoustic Oscillations and Redshift Space Distortion). Euclid will be equipped with a 1.2 m diameter mirror telescope feeding 2 instruments: a high quality panoramic visible imager (VIS); and a near infrared 3- filter photometer and a slitless spectrograph (NISP).
Euclid will carry out a wide survey covering 15,000 square degrees and a deep survey of 40 square degrees in a 6-year mission operating at the L2 Lagrangian point. The scientific analysis and interpretation of the mission data is led by the scientists of the Euclid Consortium.