Euclid is a space telescope that can able to observe in near infrared region. It is developed by European Space Agency (ESA) and Euclid consortium. The main objective of the Euclid mission is to better understand dark energy and dark matter by accurately measuring the acceleration of the universe. Generally a Korsch type of telescope will measure the shape of the galaxies which are at far distance from earth and determines the relationship between distance and redshift. Many astrophysicist believe that dark energy is responsible for increased acceleration of expanding universe. The budget of this mission if $545 million USD.
Euclid will measure the history of expansion of universe and formation of cosmic structures like nebula, black holes etc, by measuring the redshift ( increase in wavelength of radiation ) of galaxies out to a value of 2, which is equivalent to seeing back 10 billion years in the past. The relation between galaxies shapes and their corresponding redshift will show how dark energy causes increased acceleration of expanding universe. The methods employed exploit the phenomenon of gravitational lensing, measurement of baryon acoustic oscillations ( fluctuations in density of baryonic matter in universe ) , and measurement of galactic distances by spectroscopy.
SPACECRAFT
Euclid emerged from two mission concepts that were proposed in response to the ESA Cosmic Vision 2015-2025 Call for Proposals, issued in March 2007: DUNE, the Dark Universe Explorer, and SPACE, the Spectroscopic All-Sky Cosmic Explorer. Both missions proposed complementary techniques to measure the geometry of the Universe, and after an assessment study phase, a combined mission resulted. The new mission concept was called Euclid, honouring the Greek mathematician Euclid of Alexandria (~300 BC) who is considered as the father of geometry. In October 2011, Euclid was selected by ESA's Science Programme Committee for implementation, and the 25 June 2012 it was formally adopted.
Euclid will measure the history of expansion of universe and formation of cosmic structures like nebula, black holes etc, by measuring the redshift ( increase in wavelength of radiation ) of galaxies out to a value of 2, which is equivalent to seeing back 10 billion years in the past. The relation between galaxies shapes and their corresponding redshift will show how dark energy causes increased acceleration of expanding universe. The methods employed exploit the phenomenon of gravitational lensing, measurement of baryon acoustic oscillations ( fluctuations in density of baryonic matter in universe ) , and measurement of galactic distances by spectroscopy.
SPACECRAFT
Euclid emerged from two mission concepts that were proposed in response to the ESA Cosmic Vision 2015-2025 Call for Proposals, issued in March 2007: DUNE, the Dark Universe Explorer, and SPACE, the Spectroscopic All-Sky Cosmic Explorer. Both missions proposed complementary techniques to measure the geometry of the Universe, and after an assessment study phase, a combined mission resulted. The new mission concept was called Euclid, honouring the Greek mathematician Euclid of Alexandria (~300 BC) who is considered as the father of geometry. In October 2011, Euclid was selected by ESA's Science Programme Committee for implementation, and the 25 June 2012 it was formally adopted.
ESA selected Thales Alenia Space, Italy for the construction of the satellite. Euclid is 4.5 metres long with a diameter of 3.1 metres and a mass of 2160 kg.
The Euclid payload module is managed by Airbus Defence and Space, Toulouse, France. It consists of a Korsch telescope with a primary mirror 1.2 meter in diameter, which covers an area of 0.5 deg2.
An international consortium of scientists, the Euclid consortium, comprising scientists from 13 European countries and the United States, will provide a visible-light camera (VIS) and a near-infrared camera/spectrometer (NISP). Together, they will map the 3D distribution of up to two billion galaxies spread over more than a third of the whole sky. These large format cameras will be used to characterise the morphometric, photometric and spectroscopic properties of galaxies:
- a camera operating at visible wavelengths (550–920 nm) made of a mosaic of 6 x 6 e2v Charge Coupled Detectors, containing 600 million pixels, allows measurement of the deformation of galaxies
- a camera composed of a mosaic of 4 x 4 Teledyne H2RG detectors sensitive to near-infrared light radiation (1000–2000 nm) with 65 million pixels to:
- provide low precision measurements of redshifts, and thus distances, of over a billion galaxies from multi-color photometry (photometric redshift technique); and
- use a spectrometer to analyse the spectrum of light in near-infrared (1000–2000 nm), to acquire precise redshifts and distances of million galaxies, with an accuracy 10 times better than photometric redshifts, and to determine the baryon acoustic oscillations.
The telescope bus includes solar panels that provide power and stabilises the orientation and pointing of the telescope to better than 35 milliarcseconds. The telescope is carefully insulated to ensure good thermal stability so as to not disturb the optical alignment.
The telecommunications system is capable of transferring 850 gigabits per day. It uses the Ka band to send scientific data at a rate of 55 megabits per second during the allocated period of 4 hours per day to the 35-m dish Cebreros ground station in Spain, when the telescope is visible from Earth. Euclid will have an onboard storage capacity of at least 300 GB.
NASA has signed a memorandum of understanding, on 24 January 2013, with ESA describing its participation in the mission. NASA will provide 20 detectors for the near-infrared band instrument, which will operate in parallel with a camera in the visible-light band. The instruments, the telescope, and the satellite will be built and operated from Europe. NASA has also appointed 40 American scientists to be part of the Euclid consortium, which will develop the instruments and analyse the data generated by the mission. Currently, this consortium brings together more than 1000 scientists from 13 European countries and the United States.
In 2015, Euclid passed a preliminary design review, having completed a large number of technical designs as well as built and tested key components.
In December 2018, Euclid passed its critical design review, which validated the overall spacecraft design and mission architecture plan, and final spacecraft assembly was allowed to commence.
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