Décollage réussi samedi pour le télescope spatial James Webb (JWST), attendu depuis trente ans par les astronomes du monde entier pour examinationr l’Univers avec des moyens inégalés, qui va pouvoir rejoindre son million poste de 1,servation in Earth.
JWST, the most powerful space telescope ever, blasted off an Ariane 5 rocket from the Guyana Space Center at 12:20 GMT, before separating 27 minutes later, as scheduled.
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“Web well-separated telescope, Go Webb,” launch director Jean-Luc Foer announced from the Kourou Control Center urn, to thunderous applause.
“An important step has been taken,” NASA, which built the JWST in collaboration with the European Space Agency (ESA) and Canadian Space Agency (ACS), wrote on Twitter. For its part, Arianespace Group hailed the “Best Christmas Gift” of the launch.
Immediately after take-off, the telescope flew over the Atlantic Ocean, then Africa, until the final separation, which occurred at an altitude of 1,400 km and a speed of more than 34,000 km / h. An onboard camera upstairs from Ariane showed this class and especially the solar panel deployment by James Webb.
The telescope will take about a month to reach its final location. With the ambition to shed more light on humanity in two questions that torment them: “Where did we come from?” and “Are we alone in the universe?”.
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Thus we see the glimmer of the “cosmic dawn”, when the first galaxies began to illuminate the universe since the Big Bang, 13.8 billion years ago.
It will allow us to better understand the formation of stars and galaxies, and to observe exoplanets from which astronomers are discovering more and more samples, in order perhaps one day to identify other planets.
James Webb will follow in the footsteps of the Hubble telescope, which revolutionized the observation of the universe: thanks to it, scientists discovered the presence of a galactic black hole in the center of all galaxies, or water vapor around exoplanets.
Imagined by NASA since Hubble’s launch in 1990, the James Webb Space Telescope is different in more ways than one.
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The size of its mirror, with a wingspan of 6.5 meters, gives a surface area and therefore a sensitivity seven times greater, which is enough to detect the heat signature of a bumblebee on the moon.
Another difference: the method of observation. Where Hubble observes space primarily in the visible light field, James Webb ventures at a wavelength that escapes the eye: the near and mid-infrared. Radiation that any object, star, human or flower emits naturally.
This light will be studied by four instruments, equipped with imaging devices and spectrophotometers to better dissect it. Their development mobilized a large number of engineers and scientists, under the leadership of American and European laboratories and manufacturers.
Thanks to this, “by looking at the same objects (as with Hubble), we will see new things,” explained in Paris astronomer Pierre Ferot, co-head science for the telescope at the European Space Agency. For example, the first galaxies, the objects that made their lights turn red. Or the colonies of young stars that grow hidden in the clouds of dust in their nurseries. or the atmosphere of the outer planets.
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A prerequisite for the correct operation of the JWST is an ambient temperature that is too low to interfere with the light inspection.
Hubble orbits at an altitude of 600 km above Earth. At this distance, JWST would be unusable, heated by the Sun and its reflection on Earth and the Moon.
It will be placed at the end of a one-month journey 1.5 million kilometers away. It will be protected from the sun by a heat shield consisting of five flexible heat-dissipating sails that lower the temperature (80 degrees) to -233 degrees on the side of the telescope.
But before getting there, the machine and its designers will have to achieve a real breakthrough: its flawless deployment, with a series of operations that includes, for example, for the shield alone, 140 opening mechanisms, 400 reels and nearly 400 meters of cable. .
Because the observatory, 12 meters high and a shield equivalent to a tennis court, had to be folded to slip into the Ariane 5 cover. The “wrapping” was carried out with laser guidance to avoid any damage to the device, a development that cost about ten billion dollars was developed.
For these maneuvers, NASA also enforced extreme hygiene measures to avoid any contamination of the telescope mirror, by particulates or even charged breathing…
It will take several weeks to see if the telescope is ready for use. With formal entry into service scheduled for June.
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