I launched the day of Noël 2021, the James-Webb spatial telescope is now offering the first Monday cadeau: a photo constellation of objects and galaxies releases a glimpse of the universe that is already thirteen million years around of.
Clearly, the telescope far away caught the first light from the Big Bang still traveling in space (by definition at the speed of light). There’s something dizzying about the feat, especially accomplished from a planet (only) 4.54 billion years old.
It must be said that the light projected by these stellar systems must travel abysmal distances to reach us. Still need to catch it. To do this, the James Webb telescope, which has been in the making for twenty years, relies on very complex technology. BFMTV.com takes stock of the issue this Tuesday.
far orbit
When we talk about the James-Webb Space Telescope (JWST, according to the abbreviation used by the scientists who developed it), we should not imagine a telescope installed in an observatory located on the ground of cows. The spacecraft is currently 1,500,000 kilometers from Earth, in orbit around the sun. Its main mission, as the explanatory video of the Atomic Energy Commission recalls below, and decisive for the entire project: to capture infrared radiation.
The success of the task is first and foremost a question of the environment: from its altitude, the JWST benefits from the cold and stable atmosphere it needs to function optimally. The proximity of the sun also makes it necessary to redouble the means implemented to cool the machine. In addition, the telescope is equipped with a five-layer sun shield provided for this purpose.
precision engineering
This is, of course, just one of the JWST’s many accessories. It also has a 6.6-meter primary mirror, behind which four instruments will be housed, the result of the work of different space agencies: as detailed here on the official website of the Government of Canada, there is the Canadian NIRISS, the NIRCam of the American NASA. , the European NIRSpec and finally the MIRI, a joint effort between the United States and Europe.
But what exactly are these instruments? They actually comprise a camera and an integral field spectrometer. Within the constituted optical system, a filter wheel will allow the perception of infrared radiation to be adjusted. At the end of this filtering, the image will be formed on a detector.
A technology at the service of a roadmap
To go further in understanding the operations performed by the JWST, it is now necessary to highlight the roadmap.
“We know that there was a time in the history of the universe when there was not a star, not a galaxy, nothing. We call it the first primordial night of the universe. It stops with the first sunrise and the birth of the first light sources. That is the grail that we are going to look for with this telescope”, explained David Elbaz, astrophysicist and scientific director of the department of astrophysics at CEA-Irfu, on our set this Tuesday morning, before continuing:
“The universe is a history book that shows us the past. And we know that there are billions of planets, some of them analogous to Earth, and we will try to explore the atmosphere of these planets and see if they are habitable. We will try to make diagnoses to see if the planet is conducive to life, and possibly if it has hosted any.
In addition to Monday’s delivery, the telescope is preparing to release four new photos this Tuesday around 5:00 p.m. Also a guest of our antenna, Pierre-Olivier Lagage, head of the astrophysics department of the Atomic Energy Commission and scientific director of the French contribution to the James-Webb telescope, described the interest: “They will show the scope of the topics on which you can advance the JWST: the formation of stars -we will have the image of a star nursery-, the end of the life of a star, the interaction between galaxies, the spectrum of ‘an exoplanet’.
method issues
Therefore, the telescope must scan several interstellar rabbits at the same time. This involves juggling various methods. hence the need to apply two different techniques.
To uncover the secrets of exoplanets, he will use phase-mask coronagraphy. In other words, the device will associate a mask at the lens level of its optical system with a diaphragm located on the filter wheel. A combination that is the condition. condition sine qua non to dim the light of the stars and thus be able to receive the particularly weak signal sent by exoplanets that, without it, would risk being drowned in this stray luminosity.
To learn more about the life of stars and planets, the JWST will use infrared spectrography this time. The process is then as follows: the telescope records the light returned by the atmosphere of a planet when it passes in front of its star, with the idea of observing the transits of planets with small orbital periods, as proposed here by the CEA.
Cogs and neurons
But the interplay of these gears and robotics, as impressive as it is, would be in vain without one final component: the gray matter. And the designers of the JWST – some 20,000 according to the accounts made by David Elbaz – already have enough to exercise theirs.
“We have a model of the evolution of the universe and we are trying to test it. We will see these first galaxies and their evolution over time. We have a lot of information in this image that is only ‘a very small part of the universe'”, Pierre-Olivier Lagage stressed, adding that he and his colleagues “will be able to work for several months to capture everything in this image.”
This work already promises to be an exercise in modesty according to the specialist: “The more we advance in our knowledge, the more we realize our ignorance.”
Source: BFM TV
