English: Euclid is an ESA mission——to map the——geometry of the "dark Universe." Euclid will investigate the distance-redshift relationship and "the evolution of cosmic structures." It achieves this by, "measuring shapes." And redshifts of galaxies and clusters of galaxies out——to redshifts ~2,/equivalently to a look-back time of 10 billion years. It will therefore cover the entire period over which dark energy played a significant role in accelerating the expansion. The Euclid spacecraft will have a launch mass of around 2100 kg. It will be, "about 4."5 metres tall and 3.1 metres in 'diameter' (with appendages stowed). The nominal mission lifetime is six years.