After approximately one month, it reached its destination, a halo orbit around the Sun-Earth second Lagrange point L2, at an average distance of 1.5 million kilometres beyond Earth's orbit (or about four times the distance from the Earth to the Moon). There the telescope is expected to remain operational for at least six years. It joins the Gaia and James Webb Space Telescope missions at L2.
Euclid is a medium-class ("M-class") mission and is part of the Cosmic Vision campaign of ESA's Science Programme. This class of missions have an ESA budget cap at around €500 million. Euclid was chosen in October 2011 together with Solar Orbiter, out of several competing missions.[12]Euclid was launched by a Falcon 9.[13][4]
On 7 November 2023 ESA revealed Euclid 's first full-colour images of the cosmos. The telescope has created razor-sharp astronomical images across a large patch of the sky, looking far into the distant universe. The first five images illustrate Euclid 's full potential to create the most extensive 3D map of the universe yet.[14][15]
Scientific objectives and methods
Euclid will probe the history of the expansion of the universe and the formation of cosmic structures by measuring the redshift of galaxies out to a value of 2, which is equivalent to seeing back 10 billion years into the past.[16] The link between galactic shapes and their corresponding redshift will help to show how dark energy contributes to the increased acceleration of the universe. The methods employed exploit the phenomenon of gravitational lensing, measurement of baryon acoustic oscillations, and measurement of galactic distances by spectroscopy.[17]
Gravitational lensing (or gravitational shear) is a consequence of the deflection of light rays caused by the presence of matter that locally modifies the curvature of space-time: light emitted by galaxies, and therefore observed images, are distorted as they pass close to matter lying along the line of sight. This matter is composed partly of visible galaxies but it is mostly dark matter. By measuring this shear, the amount of dark matter can be inferred, furthering the understanding of how it is distributed in the universe.[18]
Spectroscopic measurements will permit measuring the redshifts of galaxies and determining their distances using Hubble's Law. In this way, one can reconstruct the three-dimensional distribution of galaxies in the universe.[16]
From these data, it is possible to simultaneously measure the statistical properties concerning the distribution of dark matter and galaxies and measure how these properties change as the spacecraft looks further back in time. Highly precise images are required to provide sufficiently accurate measurements. Any distortion inherent in the sensors must be accounted for and calibrated out, otherwise the resultant data would be of limited use.[16]
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 the father of geometry. In October 2011, Euclid was selected by ESA's Science Programme Committee for implementation, and on 25 June 2012 it was formally adopted.[1]
ESA selected Thales Alenia Space's Italian division for the construction of the satellite in Turin. Euclid is 4.5 metres long with a diameter of 3.1 metres and a mass of 2 tonnes.[3]
Meanwhile, the Euclid payload module was the responsibility of Airbus Defence and Space's French division in Toulouse. It consists of a Korsch telescope with a primary mirror 1.2 meters in diameter, which covers an area of 0.91deg2.[19][20]
An international consortium of scientists, the Euclid consortium, comprising scientists from 13 European countries and the United States, provided the visible-light camera (VIS)[7] and the near-infraredspectrometer and photometer (NISP).[8] Together, they will map the 3D distribution of up to two billion galaxies spread over more than a third of the whole sky.[21] These large-format cameras will be used to characterise the morphometric, photometric and spectroscopic properties of galaxies.
NISP, a camera composed of a mosaic of 4×4 Teledyne H2RG detectors sensitive to near-infrared light radiation (920–2020nm) with 65 million pixels, is designed for the following:
provide low-precision measurements of redshifts, and thus distances, of over a billion galaxies from multi-color (3-filter (Y, J and H)) photometry (photometric redshift technique); and
The telescope bus includes solar panels that provide power and stabilise the orientation and pointing of the telescope to better than 35 milliarcseconds (170nrad). The telescope is carefully insulated to ensure good thermal stability so as to not disturb the optical alignment.[citation needed]
The telecommunications system is capable of transferring 850 gigabits per day. It uses the Ka band and CCSDS File Delivery Protocol to send scientific data at a rate of 55 megabits per second during the allocated period of 4 hours per day to the 35m dish Cebreros ground station in Spain, when the telescope is above the horizon. Euclid has an onboard storage capacity of at least 300GB.[24][failed verification]
The service module (SVM) hosts most of the spacecraft subsystems:[citation needed]
TT&C – Telemetry and Telecommand
AOCS – Attitude Orbit Control System
CDMS – Central Data Management System
EPS – Electrical Power System
RCS – Reaction Control System
MPS – Micro-Propulsion System
AOCS provides stable pointing with a dispersion beneath 35 milli-arcseconds per visual exposure. A high thermal stability is required to protect the telescope assembly from optical misalignments at those accuracies.[24]
Milestones
NASA signed a memorandum of understanding with ESA on 24 January 2013 describing its participation in the mission. NASA provided 20 detectors for the near-infrared band instrument, which operate in parallel with a camera in the visible-light band. The instruments, the telescope, and the satellite were built in and are 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.[25]
In 2015, Euclid passed a preliminary design review, having completed a large number of technical designs as well as built and tested key components.[26]
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.[27]
In July 2020, the two instruments (visible and NIR) were delivered to Airbus, Toulouse, France for integration with the spacecraft.[28]
After Russia withdrew in 2022 from the Soyuz-planned launch of Euclid, the ESA reassigned it to a SpaceX Falcon 9 launch vehicle, which launched on 1 July 2023.[13][29][11]
Following a travel time of 30 days after launch, it began to orbit the Sun-Earth Lagrangian point L2[3] in an eclipse-free halo orbit about 1 million km wide.
Upon receiving the initial images, a problem surfaced as scientists discovered a small gap in the spacecraft's hull. This gap allowed sunlight to infiltrate the imaging sensor, resulting in a degradation of image quality.[30] To tackle this issue, the team adjusted the spacecraft's orientation by a few degrees, effectively blocking sunlight from entering the identified gap. This corrective measure successfully resolved the problem.[31]
During its nominal mission, which will last at least six years, Euclid will observe about 15,000deg2 (4.6sr), about a third of the sky, focusing on the extragalactic sky (the sky facing away from the Milky Way).[2] It will generate approximately 100 gigabytes of compressed data per day throughout its six-year mission.[32] The survey will be complemented by additional observations of three deep fields to 5 times the signal-to-noise of the wide survey; the deep fields cover 50deg2 (15.2msr).[33] The three fields will be regularly visited during the whole duration of the mission. They will be used as calibration fields and to monitor the telescope and instrument performance stability as well as to produce scientific data by observing the most distant galaxies and quasars in the universe.[34] Two of the deep fields will overlap with deep fields of existing surveys[35] and the third deep field is proposed as a location for one of the LSST deep drilling fields at the Vera C. Rubin Observatory.[36]
To measure a photometric redshift for each galaxy with sufficient accuracy, the Euclid mission depends on additional photometric data obtained in at least four filters at optical wavelengths. This data will be obtained from ground-based telescopes located in both northern and southern hemispheres to cover the full 15,000deg2 of the mission.[37][38] In total each galaxy of the Euclid mission will get photometric information in at least seven different filters covering the whole range 460–2000nm.[39]
About 10 billion astronomical sources will be observed by Euclid, of which one billion will be used for weak lensing (to have their gravitational shear measured)[40] with a precision 50 times more accurate than is possible today using ground-based telescopes. Euclid will measure spectroscopic redshifts for at least 30 million objects to study galaxy clustering.
The scientific exploitation of this enormous data set will be carried out by a European-led consortium of more than 1200 people in over 100 laboratories in 18 countries (Austria, Belgium, Denmark, Finland, France, Germany, Italy, the Netherlands, Norway, Portugal, Romania, Spain, Switzerland, UK, Canada, US, and Japan).[41] The Euclid Consortium[40] is also responsible for the construction of the Euclid instrument payload and for the development and implementation of the Euclid ground segment which will process all data collected by the satellite. The laboratories contributing to the Euclid Consortium are funded and supported by their national space agencies, which also have the programmatic responsibilities of their national contribution, and by their national research structures (research agencies, observatories, universities). Overall, the Euclid Consortium contributes to about 25% of the total budget cost of the mission until completion.[42]
The huge volume, diversity (space and ground, visible and near-infrared, morphometry, photometry, and spectroscopy) and the high level of precision of measurements demanded considerable care and effort in the data processing, making this a critical part of the mission. ESA, the national agencies and the Euclid Consortium are spending considerable resources to set up top-level teams of researchers and engineers in algorithm development, software development, testing and validation procedures, data archiving and data distribution infrastructures. In total, nine Science Data Centres spread over countries of the Euclid Consortium will process more than 170 petabytes of raw input images over at least 6 years to deliver data products (images, catalogues spectra) in three main public data releases in the Science Archive System of the Euclid mission to the scientific community.[43][39]
Around the Sun – Frame rotating with Earth – Top view
Around the Sun – Frame rotating with Earth – Viewed from the Sun
Euclid· Earth· Sun-Earth L2
Gallery of first test images
Euclid scans across the night sky using a 'step-and-stare' method, combining separate measurements to form the largest cosmological survey ever conducted in the visible and near-infrared.
Early commissioning test image VIS instrument
Early commissioning test image NISP instrument
Early commissioning test image NISP instrument grism mode
The Wilkinson Microwave Anisotropy Probe (WMAP), originally known as the Microwave Anisotropy Probe, was a NASA spacecraft operating from 2001 to 2010 which measured temperature differences across the sky in the cosmic microwave background (CMB) – the radiant heat remaining from the Big Bang. Headed by Professor Charles L. Bennett of Johns Hopkins University, the mission was developed in a joint partnership between the NASA Goddard Space Flight Center and Princeton University. The WMAP spacecraft was launched on 30 June 2001 from Florida. The WMAP mission succeeded the COBE space mission and was the second medium-class (MIDEX) spacecraft in the NASA Explorer program. In 2003, MAP was renamed WMAP in honor of cosmologist David Todd Wilkinson (1935–2002), who had been a member of the mission's science team. After nine years of operations, WMAP was switched off in 2010, following the launch of the more advanced Planck spacecraft by European Space Agency (ESA) in 2009.
XMM-Newton, also known as the High Throughput X-ray Spectroscopy Mission and the X-ray Multi-Mirror Mission, is an X-ray space observatory launched by the European Space Agency in December 1999 on an Ariane 5 rocket. It is the second cornerstone mission of ESA's Horizon 2000 programme. Named after physicist and astronomer Sir Isaac Newton, the spacecraft is tasked with investigating interstellar X-ray sources, performing narrow- and broad-range spectroscopy, and performing the first simultaneous imaging of objects in both X-ray and optical wavelengths.
The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. Its high-resolution and high-sensitivity instruments allow it to view objects too old, distant, or faint for the Hubble Space Telescope. This enables investigations across many fields of astronomy and cosmology, such as observation of the first stars and the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets.
The Infrared Space Observatory (ISO) was a space telescope for infrared light designed and operated by the European Space Agency (ESA), in cooperation with ISAS and NASA. The ISO was designed to study infrared light at wavelengths of 2.5 to 240 micrometres and operated from 1995 to 1998.
Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors.
Gaia is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until 2025. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented precision, and the positions of exoplanets by measuring attributes about the stars they orbit such as their apparent magnitude and color. The mission aims to construct by far the largest and most precise 3D space catalog ever made, totalling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars, among others.
The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was active from 2009 to 2013, and was the largest infrared telescope ever launched until the launch of the James Webb Space Telescope in 2021. Herschel carries a 3.5-metre (11.5 ft) mirror and instruments sensitive to the far infrared and submillimetre wavebands (55–672 µm). Herschel was the fourth and final cornerstone mission in the Horizon 2000 programme, following SOHO/Cluster II, XMM-Newton and Rosetta.
Planck was a space observatory operated by the European Space Agency (ESA) from 2009 to 2013. It was an ambitious project that aimed to map the anisotropies of the cosmic microwave background (CMB) at microwave and infrared frequencies, with high sensitivity and small angular resolution. The mission was highly successful and substantially improved upon observations made by the NASA Wilkinson Microwave Anisotropy Probe (WMAP).
The Solar Orbiter (SolO) is a Sun-observing probe developed by the European Space Agency (ESA) with a National Aeronautics and Space Administration (NASA) contribution. Solar Orbiter, designed to obtain detailed measurements of the inner heliosphere and the nascent solar wind, will also perform close observations of the polar regions of the Sun which is difficult to do from Earth. These observations are important in investigating how the Sun creates and controls its heliosphere.
International Ultraviolet Explorer, was the first space observatory primarily designed to take ultraviolet (UV) electromagnetic spectrum. The satellite was a collaborative project between NASA, the United Kingdom's Science and Engineering Research Council and the European Space Agency (ESA), formerly European Space Research Organisation (ESRO). The mission was first proposed in early 1964, by a group of scientists in the United Kingdom, and was launched on 26 January 1978 aboard a NASA Thor-Delta 2914 launch vehicle. The mission lifetime was initially set for 3 years, but in the end it lasted 18 years, with the satellite being shut down in 1996. The switch-off occurred for financial reasons, while the telescope was still functioning at near original efficiency.
Wide-field Infrared Explorer was a NASA satellite launched on 5 March 1999, on the Pegasus XL launch vehicle into polar orbit between 409 and 426 km above the surface of Earth. WIRE was intended to be a four-month infrared survey of the entire sky at 21-27 µm and 9-15 µm, specifically focusing on starburst galaxies and luminous protogalaxies.
The Great Observatories Origins Deep Survey, or GOODS, is an astronomical survey combining deep observations from three of NASA's Great Observatories: the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory, along with data from other space-based telescopes, such as XMM Newton, and some of the world's most powerful ground-based telescopes.
The Joint Dark Energy Mission (JDEM) was an Einstein probe that planned to focus on investigating dark energy. JDEM was a partnership between NASA and the U.S. Department of Energy (DOE).
PLAnetary Transits and Oscillations of stars (PLATO) is a space telescope under development by the European Space Agency for launch in 2026. The mission goals are to search for planetary transits across up to one million stars, and to discover and characterize rocky extrasolar planets around yellow dwarf stars, subgiant stars, and red dwarf stars. The emphasis of the mission is on Earth-like planets in the habitable zone around Sun-like stars where water can exist in a liquid state. It is the third medium-class mission in ESA's Cosmic Vision programme and is named after the influential Greek philosopher Plato. A secondary objective of the mission is to study stellar oscillations or seismic activity in stars to measure stellar masses and evolution and enable the precise characterization of the planet host star, including its age.
The Galaxy And Mass Assembly (GAMA) survey is a project to exploit the latest generation of ground-based wide-field survey facilities to study cosmology and galaxy formation and evolution. GAMA will bring together data from a number of world class instruments:
CHEOPS is a European space telescope. Its objective is to determine the size of known extrasolar planets, which will allow the estimation of their mass, density, composition and their formation. Launched on 18 December 2019, it is the first Small-class mission in ESA's Cosmic Vision science programme.
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SPHEREx is a future near-infrared space observatory that will perform an all-sky survey to measure the near-infrared spectra of approximately 450 million galaxies. In February 2019, SPHEREx was selected by NASA for its next Medium-Class Explorers mission, beating out two competing mission concepts: Arcus and FINESSE. As of August 2022, SPHEREx is targeted to launch no earlier than April 2025 on a Falcon 9 launch vehicle from Vandenberg Space Force Base. The principal investigator is James Bock at California Institute of Technology (Caltech) in Pasadena, California.
Peter Lawrence Capak is currently the Architect of Perception Systems at the Oculus division of Facebook. His current focus is developing machine perception technologies, sensors, displays, and compute architectures for the next generation of augmented (AR), mixed (MR) and virtual reality (VR) systems. His research has focused on using physical modeling and advanced statistical methods including artificial intelligence and machine learning to extract information from very large multi-wavelength (hyper-spectral) data sets. He has primarily used this to study structure formation in the universe, cosmology, and the nature of dark matter and dark energy.
↑ Racca, Giuseppe D.; etal. (2016). "The Euclid mission design". In MacEwen, Howard A.; Fazio, Giovanni G.; Lystrup, Makenzie; Batalha, Natalie; Siegler, Nicholas; Tong, Edward C. (eds.). Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave. Vol.9904. pp.99040O. arXiv:1610.05508. doi:10.1117/12.2230762. S2CID118513194.
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).
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