Case study


Mapping the geometry and nature of dark energy and dark matter with unprecedented accuracy.

Euclid spacecraft.
Artist's impression of the Euclid spacecraft. Credit: ESA.

Euclid is a high-precision survey mission to map the geometry of the Dark Universe and would effectively look back in time about 10 billion years, covering the period over which dark energy seems to have accelerated the expansion of the Universe. Mission overview:

  • the mission has now been selected to go forward as the M2 medium-class mission in ESA’s Cosmic Vision programme
  • launch scheduled for 2020
  • the multi lateral agreement between ESA and contributing nations was signed in November 2013
  • the nominal mission lifetime is 5 years, with scientific operations taking at least 4.5 years

Until about thirty years ago astronomers thought that the Universe was composed almost entirely of ordinary matter - protons, neutrons, electrons and atoms. In the intervening years the emerging picture of the composition of the Universe has changed dramatically.

It is now assumed that ordinary matter makes up only about 4% of the Universe, and that the mass-energy budget of the Universe is actually dominated by two mysterious components: dark energy and dark matter. This will be the focus for Euclid.

For more detailed information please see the Euclid pages on the ESA website.

Mission facts

The mission name ‘Euclid’ honours the Greek mathematician Euclid of Alexandria (~300 BC) who is considered as ‘the father of geometry’. Euclid will be launched by a Russian Soyuz ST launch vehicle and operate at L2 (second Lagrange point) which will ensure stable thermal and observing conditions.

As currently planned, Euclid would use two different methods to build its map. One of the methods – weak gravitational lensing – maps the dark matter and measures dark energy by measuring the distortions of galaxy images. The other method involves studying baryonic acoustic oscillations – wiggle patterns – imprinted in the clustering of galaxies, which provide a standard against which to measure dark energy and expansion in the Universe.

Dedicated teams from instrument consortia will process the very large volumes of high precision data generated from their instruments during the mission at specialised Instrument Operations Centres (IOCs) and several Science Data Centres (SDCs). The IOCs will be responsible for the first level standard data processing (calibration, removal of the instrumental effects, etc) and the SDCs will be in charge of second and third level data products and the development of simulation pipelines.


The mission design includes a telescope with a primary mirror of 1.2m diameter, feeding three scientific instrument channels:

  • the VIS (Visible Imager) for the weak lensing technique; the Focal Plane design is being lead by the UK
  • the NIP (Near Infrared Photometer) for the measure of the photometric redshifts
  • the NIS (Near Infrared Spectrometer) for the baryonic acoustic oscillations technique.

UK involvement

Nine institutes have involvement in instrument development or data processing / analysis activities. These are:

  • Mullard Space Science Laboratory of the University College London
  • Durham University
  • Institute for Astronomy, Edinburgh
  • UK ATC (Astronomy Technology Centre)
  • University of Oxford
  • University of Portsmouth
  • University of Hertfordshire
  • Open University
  • University of Cambridge
  • University College London

Funding from the UK Space Agency will allow the teams to take the UK development activities forward into the next phase.

UK industry will play a key role in mission development. CCDs are being developed by e2v, and other industrial involvement will be confirmed following mission selection.

Published 25 April 2014