Astronomers have been talking about it for twenty years. After several delays and delays, the James Webb Telescope is set to launch this Saturday, December 25, thanks to an Ariane 5 rocket. Franceinfo explains why this new telescope, whose costs have exploded to reach $ 10 billion (8.9 billion euros) – funded by NASA, the European Space Agency and the Canadian Space Agency – will revolutionize space observation, whether it’s scrutiny relatively dense or very distant objects.
Because it’s the most powerful telescope ever sent into space
The James Webb Space Telescope (JWST), also simply called the James Webb, is considered as a jewel of space technology. It is equipped with a large mirror composed of 18 small hexagonal mirrors. Once in the room, the collection should unfold like an origami, as shown in this video (English).
When inserted, the JWST is 8 meters high and its five-layer thick awning spans an area the size of a tennis court. “Usually, mechanisms like those at JWST are a fear of space engineers. ” by that they fear that they will block or that they open poorly, says to franceinfo Olivier Berné, astrophysicist at CNRS. “There are hundreds of them there. It’s unprecedented, and it’s an already extraordinary mission from that point of view. “comments the one who is also responsible for a scientific project on James Webb.
Above all, the JWST, which weighs 6 tons, is the most powerful telescope ever sent into space. Returning to the mirror, which makes it possible to measure the power of a telescope, the of Launched in 1990, Hubble is 2.4 meters wide, while JWST is 6.5, as this NASA video explains (English).
Specifically, since James Webb’s mirror is larger than Hubble’s, it can capture more light and therefore look much longer. Which also has a better resolution.
“It is a hole technology achieved with James Webb, thanks to instruments never built before. “Anthony Boccaletti, astronomer at the Meudon Observatory
at france info
Unlike its cousins on Earth, JWST will not be hindered by the light and atmosphere of our planet: it will be located 1.5 million kilometers from us at the second Lagrange point (while Hubble is in orbit 570 km above our heads).
Because it will allow us to see the universe in new ways
“One of the scientific goals of JWST is to look at the light from the first stars formed shortly after the big bang.explains Olivier Berné. We do not really know how these first stars were created, necessary to enrich the universe with heavier chemical elements. “he continues.
But in order to look at such ancient and distant objects, it is necessary to be placed in the infrared. In fact, the universe is expanding, the planets, galaxies are constantly moving away from us. At this distance, the light from these celestial bodies shifts to the red, a phenomenon called “Doppler effect” in French (“red switch “ English).
Designed to work in the infrared, JWST will thus be able to probe the universe very deeply and for the first time observe very ancient objects formed 13.5 billion years ago (compared to 12.5 billion years for Hubble). In other words, we will be able to observe the universe since it was very young since the big bang took place about 13.7 billion years ago. Michel Blanc, astronomer emeritus at the Department of Research in Astrophysics and Planetology, evokes a “huge breakthrough”.
“While Hubble has employed observation in visible light and ultraviolet very well, James Webb is working above all in the infrared. It is opening new doors.”Michel Blanc, astronomer
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To better understand the contribution of infrared, here is an example of what it allows compared to visible light. In these two photos taken by Hubble and posted via James Webb’s official Twitter account, is the left image in visible light. The one on the right, in infrared light. We notice that on the other hand, the visible objects are much more numerous and that the infrared makes it possible to see through the dust.
.@NASAHubble demonstrates the differences between visible (left) and infrared (right) light in these images of a star kindergarten. #NASAWebb will see even more infrared light, and is working with Hubble to reveal more of our universe. Credit: NASA, ESA, STScI # FogNovember pic.twitter.com/EUEclK5gbX
—NASA Webb Telescope (@NASAWebb) November 21, 2021
And here’s a simulation of what James Webb might be able to do. The image on the left shows visible light, the image on the right gives an idea of what JWST could produce.
Webb is a heat finder that will detect invisible infrared light, unlike our phone cameras, which photograph visible light. The cameras on Web’s NIRCam and NIRISS instruments will both look in the near-infrared range, while its MIRI instrument will take pictures in mid-infrared. pic.twitter.com/pvTMOx6t6E
—NASA Webb Telescope (@NASAWebb) June 29, 2021
Working specifically in the infrared is nothing new. The Spitzer Telescope specializes in this area. But James Webb is 1,000 times stronger than the latter, according to NASA (English).
Such detailed observations will have several consequences. If he is careful about the content of the upcoming discoveries, Anthony Boccaletti, astronomer at the Observatory of Meudon (Hauts-de-Seine), tells Franceinfo to be “certain” that JWST will be the cause of important advances in our knowledge.
“There will be great progress in many areas of astrophysics thanks to JWST.”Anthony Boccaletti
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Because it will make it possible to rediscover already known celestial bodies
His ability to work in the infrared also allows James Webb to observe cold bodies, which are harder to detect. This is what will be shown by Thierry Fouchet, from the Laboratory for Space Studies and Instrumentation in Astrophysics in Paris.
He is working on a project that illustrates the possibilities of JWST. He will not point it in the direction of a distant object, but will dwell on those who are relatively close to us and cold: Jupiter, its rings, and its moons. By pushing James Webb’s tools to its limits, he will, among other things, study the satellites on the largest planet in our solar system, such as Io, Ganymede and Callisto. Its purpose: to map the ice on its surface, determine its age, its temperature, the rate at which it recomposes.
For the study of Jupiter, he admits he does not expect surprising news. “We want to be more in sophistication” of our current knowledge, he admits. The discoveries are rather expected for the satellites.
“I would not be surprised if someone is surprised. We have very little information. It is not clear what to expect and nothing has been solidly verified yet.”Thierry Fouchet, astrophysicist at the Paris Observatory
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Because it will help us to know exoplanets better
Since the discovery of the first planet outside our solar system in 1995, new discoveries have flooded in. Except that these often very distant stars are still unknown. “JWST will make it possible to observe them with unmatched precision”comments Olivier Berné, astrophysicist at CNRS and scientific project manager for the telescope.
“We will be able to look into planetary systems as if we were looking at our own. This is something particularly new.”Olivier Berné, astrophysicist
at france info
Astrophysicists will get accurate information about the composition of the atmosphere on exoplanets, such as temperature, density. They will also have data on the presence or absence of “organic molecules that can be precursors to life”notes the astrophysicist.
Targeted exoplanets “are very young, very large and very warm. So they can not support life or be habitable”temperament Anthony Boccaletti. “Discovering a habitable exoplanet and telling yourself that there is life elsewhere in the universe is the ultimate goal, but that’s not the majority of the observations we’re going to make with James Webb.”he adds.
Because it paves the way for the observation of very little studied phenomena
Nicole Nesvadba, an astrophysicist at the Observatoire de la Côte d’Azur, is interested in supermassive black holes, which are found in the center of galaxies and are between one million and several billion solar masses. If the first direct image of a supermassive black hole was published in 2019, “We know very little about these quite unusual phenomena“, She explains to franceinfo.
According to her, JWST will most likely be “revolutionary” to understand how supermassive black holes interact with their surroundings. It allows you to observe “in details” a phenomenon that has not been studied “seriously” only once thanks to the Spitzer telescope about ten years ago, she explains.
With JWST, researchers in particular will be able to take a closer look “galactic winds” generated by the supermassive black hole in the galaxy 3C326N, which is about 1 billion light-years from Earth. In the field of view: gases that can not be observed from the ground. Their behavior may shed light on why this galaxy has not formed stars for ten billion years.