Scientia —
Euclid is an ESA medium class astronomy and astrophysics space mission. Euclid was selected by ESA in October 2011 (see the Euclid ESA page). Its launch is planned for Q1 2020. In June 2012 ESA officially selected the “Euclid Consortium” as the single team having the scientific responsibility of the mission, the data production and of the scientific instruments.
The Euclid mission aims at understanding why the expansion of the Universe is accelerating and what is the nature of the source responsible for this acceleration which physicists refer to as dark energy. Dark energy represents around 75% of the energy content of the Universe today, and together with dark matter it dominates the Universes’ matter-energy content. Both are mysterious and of unknown nature but control the past, present and future evolution of Universe.
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, as well as on the physics of the early universe and 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).
To accomplish the Euclid mission ESA has selected Thales Alenia Space (see also the ESA press release ) for the construction of the satellite and its Service Module and Airbus Defence and Space (ex-Astrium) for the Payload Module.
Euclid will be equipped with a 1.2 m diameter Silicon Carbide (SiC) mirror telescope made by Airbus Defence and Space feeding 2 instruments, VIS and NISP, built by the Euclid Consortium : a high quality panoramic visible imager (VIS), a near infrared 3-filter (Y, J and H) photometer (NISP-P) and a slitless spectrograph (NISP-S). With these instruments physicists will probe the expansion history of the Universe and the evolution of cosmic structures by measuring the modification of shapes of galaxies induced by gravitational lensing effects of dark matter and the 3-dimension distribution of structures from spectroscopic redshifts of galaxies and clusters of galaxies.
The satellite will be launched by a Soyuz ST-2.1B rocket and then travel to the L2 Sun-Earth Lagrangian point for a 6 years mission.
Euclid will observe 15,000 deg2 of the darkest sky that is free of contamination by light from our Galaxy and our Solar System (see the ESA Euclid mission summary ). Two “Euclid Deep Fields” covering around 20 deg2 each will be also observed extending the scientific scope of the mission the high-redshift universe.
The complete survey represents hundreds of thousands images and several tens of Petabytes of data. About 10 billion sources will be observed by Euclid out of which more than 1 billion will be used for weak lensing and several tens of million galaxy redshifts will be also measured and used for galaxy clustering. The scientific analysis and interpretation of these data is led by the scientists of the Euclid Consortium.
Euclid Scientific Objectives
Euclid is primarily a cosmology and fundamental physics mission. Its main scientific objective is to understand the source of the accelerating expansion of the Universe and discover its very nature that physicists refer to as dark energy.
Euclid will then address to the following questions:
- is dark energy merely a cosmological constant, as first discussed by Einstein, or
- is it a new kind of field that evolves dynamically with the expansion of the universe?
- alternatively, is dark energy instead a manifestation of a breakdown of General Relativity and deviations from the law of gravity?
- what are the nature and properties of dark matter?
- what are the initial conditions which seed the formation of cosmic structure?
- what will be the future of the Universe over the next ten billion years?
The imprints of dark energy and gravity will be detected from their signatures on the expansion rate of the Universe and the growth of cosmic structures using gravitational lensing effects on galaxies (Weak Lensing) and the properties of galaxy clustering (Baryonic Acoustic Oscillations and Redshift Space Distortion). Baryon acoustic oscillations provide a direct distance-redshift probe to explore the expansion rate of the Universe. Weak lensing provides an almost direct probe of dark matter but combines together angular distances that probes the expansion rate and the mass density contrast that probe the growth rate of structure and gravity. In contrast, redshift space distortion probes the growth rate of cosmic structures and gravity. Combined together these three probes are solid and complementary probes of the effects of dark energy.
These observations will be complemented by independent observations also derived from Euclid data on clusters of galaxies and the Integrated Sachs-Wolf effect. They will be used to cross-check the results obtained from Weak Lensing, Baryonic Acoustic Oscillations and Redshift Space Distortion and to better understand and control systematic errors.
Illustration of the primary probes of the Euclid mission. Left: Baryon acoustic oscillations, (BAO), Redshift Space Distortion (RSD). Right: Weak Lensing (WL)- Courtesy Euclid Consortium/Science Working Group.
– Credit and Resource –
For more information, check out the Euclid site from our awesome friends at the ESA.
The Euclid Spacecraft
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