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Jul 15, 2023

Le télescope spatial Euclide va faire la lumière sur l’univers sombre

Par University College London2 août 2023

La mission Euclid de l'ESA est un projet très ambitieux entrepris par l'Agence spatiale européenne (ESA) pour étudier et comprendre la nature de deux composantes énigmatiques de notre Univers : la matière noire et l'énergie noire. Lancé le 1er juillet 2023, le vaisseau spatial observera des milliards de galaxies jusqu'à 10 milliards d'années-lumière pour construire la carte 3D la plus précise de l'Univers jamais réalisée. Crédit : ESA

Euclid, a space mission led by the European Space AgencyThe European Space Agency (ESA) is an intergovernmental organization dedicated to the exploration and study of space. ESA was established in 1975 and has 22 member states, with its headquarters located in Paris, France. ESA is responsible for the development and coordination of Europe's space activities, including the design, construction, and launch of spacecraft and satellites for scientific research and Earth observation. Some of ESA's flagship missions have included the Rosetta mission to study a comet, the Gaia mission to create a 3D map of the Milky Way, and the ExoMars mission to search for evidence of past or present life on Mars." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">L'Agence spatiale européenne (ESA), qui comprend une immense caméra optique conçue et construite par des chercheurs de l'University College de Londres (UCL), cartographiera les structures à grande échelle de l'univers pour mieux comprendre deux composants mystérieux : la matière noire et l'énergie noire.

Tout ce que nous pouvons voir et détecter dans le monde qui nous entoure – les étoiles, les galaxies, les fleurs, notre corps, les atomes – ne représente que 5 % de l’univers. Le reste, selon les théories actuelles, est constitué de deux composantes : la matière noire et l’énergie noire. Leur existence est déduite indirectement. La matière noire maintient les galaxies ensemble ; L'énergie noire accélère l'expansion de l'univers. Mais ce qu’ils sont est inconnu. Aujourd’hui, un télescope a été lancé dans l’espace pour aider à percer ce mystère.

Le professeur Tom Kitching, du Mullard Space Science Laboratory de l'UCL, est l'un des quatre coordinateurs scientifiques de la mission Euclid dirigée par l'Agence spatiale européenne. Il affirme que les données qu’il rapporte ont le potentiel de déterminer si l’énergie noire est ou non une « énergie du vide » – l’énergie de particules virtuelles qui apparaissent et disparaissent dans l’espace vide. Si tel est le cas, les théories fondamentales de la physique des particules devront être révisées, car cette énergie du vide devra être beaucoup plus forte que ce que prédisent les théories actuelles. Sinon, c'est la théorie de la gravité d'Einstein qui pourrait être fausse. « Dans tous les cas, ce serait une révolution en physique », dit-il.

Une réplique du vaisseau spatial Euclid dans les locaux de Thales Alenia Space à Cannes, France, en 2019. Crédit : Stéphane Corvaja/ESA

La mission est un projet collaboratif massif : le consortium qui l’a proposé à lui seul est composé de 2 000 scientifiques et ingénieurs répartis dans 15 pays. Le télescope dispose de deux instruments. L’un d’entre eux, le spectromètre et photomètre proche infrarouge (NISP), capturera la lumière du spectre invisible du proche infrarouge. L’autre, baptisé VIS, va capter la lumière visible. Le professeur Mark Cropper (UCL Mullard Space Science Laboratory) (photo ci-dessous) a dirigé la conception et le développement de la caméra optique VIS pendant plus de 16 ans, en collaboration avec des équipes de l'UCL, de l'Open University et de toute l'Europe.

Professeur Mark Cropper, Laboratoire de sciences spatiales UCL Mullard. Crédit : UCL

La caméra, l’une des plus grandes jamais envoyées dans l’espace, prendra des images panoramiques haute résolution d’une grande partie de l’univers, remontant à 10 milliards d’années et couvrant un tiers du ciel nocturne. À l’aide de ces données, les astronomes mesureront la forme de deux milliards de galaxies et utiliseront une technique appelée lentille gravitationnelle faible – observant comment la lumière des galaxies lointaines a été courbée par la gravité de la matière intermédiaire sur son chemin vers le télescope – pour en déduire la forme à grande échelle. distribution de la matière visible et noire plus précisément qu'auparavant.

VIS’s wide field of view means that, while it will take images nearly as sharp as the Hubble Space TelescopeThe Hubble Space Telescope (often referred to as Hubble or HST) is one of NASA's Great Observatories and was launched into low Earth orbit in 1990. It is one of the largest and most versatile space telescopes in use and features a 2.4-meter mirror and four main instruments that observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. It was named after astronomer Edwin Hubble." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"Hubble Space Telescope, it will cover a much larger area of the sky – covering the same area in one day as Hubble covered over 25 years. Each image would require 300 high-definition TV screens to display. Over six years it will allow the shape of more than 1.5 billion galaxies to be measured. “These are huge, unprecedented images,” says Professor Cropper./p>

The laboratory, located in a Victorian mansion in the Surrey Hills, is staffed by 60 engineers and 140 scientists. It has supported 300 space missions. Instruments designed and built at MSSL have reached many corners of the solar system, from MarsMars is the second smallest planet in our solar system and the fourth planet from the sun. It is a dusty, cold, desert world with a very thin atmosphere. Iron oxide is prevalent in Mars' surface resulting in its reddish color and its nickname "The Red Planet." Mars' name comes from the Roman god of war." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">Mars to SaturnSaturn is the sixth planet from the sun and has the second-largest mass in the Solar System. It has a much lower density than Earth but has a much greater volume. Saturn's name comes from the Roman god of wealth and agriculture." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"Saturn to close to the Sun, and have helped illuminate the most distant galaxies. A model of Britain’s first rocket, the Skylark, sits at the bottom of a staircase./p>

When I visit shortly before the Euclid launch, engineers in a clean room (pictured above) are testing a plasmaPlasma is one of the four fundamental states of matter, along with solid, liquid, and gas. It is an ionized gas consisting of positive ions and free electrons. It was first described by chemist Irving Langmuir in the 1920s." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"plasma analyzer for a space weather satellite, Vigil (due to launch in the mid-2020s), by firing ions at it. Nitrogen is piped in through tubes to keep instruments cold, mimicking the environment in space./p>

This process — part of the ground segment, or ground-based element of the mission — is painstaking but crucial. “Every step of the ground segment has to be perfectly done,” says Professor Joachimi. “Any tiny mistake can mess up the science that comes out at the end. Some of the accuracyHow close the measured value conforms to the correct value." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"accuracy requirements can be measured as parts per million.” Euclid’s sharp view of galaxies – its increased resolution compared to previous surveys of the universe – “ups the ante on how accurately we have to process that information.”/p>

On July 1, 2023, Euclid successfully launched aboard a SpaceXCommonly known as SpaceX, Space Exploration Technologies Corp. is a private American aerospace manufacturer and space transport services company that was founded by Elon Musk in 2002. Headquartered in Hawthorne, California, the company designs, manufactures, and launches advanced rockets and spacecraft. SpaceX's ultimate goal is to reduce space transportation costs and enable the colonization of Mars." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station in Florida, USA. Its instruments were turned on 11 days later. The spacecraft has now reached the second Lagrangian Point, a stable hovering spot about 1.5 million kilometers (1 million miles) from Earth, joining the NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is "To discover and expand knowledge for the benefit of humanity." Its core values are "safety, integrity, teamwork, excellence, and inclusion." NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">NASA-led James Webb Space TelescopeThe James Webb Space Telescope (JWST or Webb) is an orbiting infrared observatory that will complement and extend the discoveries of the Hubble Space Telescope. It covers longer wavelengths of light, with greatly improved sensitivity, allowing it to see inside dust clouds where stars and planetary systems are forming today as well as looking further back in time to observe the first galaxies that formed in the early universe." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"James Webb Space Telescope and the ESA Gaia mission: UCL-MSSL provided parts of both of those missions too./p>Euclid, a space mission led by the European Space AgencyThe European Space Agency (ESA) is an intergovernmental organization dedicated to the exploration and study of space. ESA was established in 1975 and has 22 member states, with its headquarters located in Paris, France. ESA is responsible for the development and coordination of Europe's space activities, including the design, construction, and launch of spacecraft and satellites for scientific research and Earth observation. Some of ESA's flagship missions have included the Rosetta mission to study a comet, the Gaia mission to create a 3D map of the Milky Way, and the ExoMars mission to search for evidence of past or present life on Mars." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"European Space Agency (ESA) that includes a massive optical camera designed and built by University College London (UCL) researchers, will map the large-scale structures of the universe to better understand two mysterious components: dark matter and dark energy./strong>

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