VIDEO.James Webb space telescope: Relive its launch this Saturday
By Johann Foucault published updated lemis on 25 Dec 21 to 16: 00 act my news
Successful takeoff this Saturday, December 25, 2021 for the James Webb space telescope (JWST), expected for thirty years by astronomers around the world to examine the universe with unrivaled means, which will be able to join its observation post, 1, 1,5 million km of the earth.
The JWST, the most powerful space telescope never designed, took off with an Ariane 5 rocket from the Guyanese space center at 12:20 GMT, before separating 27 minutes later, as expected.
See the first galaxies
Imagined by NASA from the launch of Hubble in 1990, and built from 2004, with the collaboration of European space agencies (ESA) and Canadian (CSA), the JWST is distinguished in more than one way.
The size of its mirror, 6.5 meters wide, gives it a surface and therefore a sensitivity seven times greater, sufficient to detect the thermal signature of a bumblebee on the moon.
Another difference: its mode of observation.Where Hubble observes the space essentially in the field of visible light, James Webb ventures in a wavelength escaping the eye: the near and average infrage.A radiation that any body, star, human or flower, naturally emits.
This light will be studied by four instruments, equipped with imaging and spectrographs to better dissect it.Their development has mobilized a plethora of engineers and scientists, under the leadership of American and European laboratories and industrialists.
Thanks to that "looking at the same objects (as with Hubble), we will see new things", explained in Paris the astronomer Pierre Ferruit, a scientific co-responsible for the telescope for the ESA.For example the first galaxies, objects whose distance has made their light turn to red.Or the young stars colonies, who grow up masked in the dust clouds of their bumps.Or the atmosphere of exoplanets.
A 1.5 million km trip
The imperative condition for the proper functioning of the JWST is a room temperature so low that it does not disturb the light examination.
Hubble is in orbit some 600 km above the earth.At this distance, the jwst would be unusable, heated by the sun and its reflection on the earth and the moon.
It will be placed after a one -month trip to 1.5 million km away.And will be protected from solar radiation by a thermal shield of five flexible sails which will dissipate heat, lowering the temperature (which is 80 °) to -233 degrees on the telescope side.
Avoid contaminations
But before arriving there, the machine and its designers will have to achieve a real feat: its unfailing deployment, with a series of operations involving for example for the only shield 140 opening mechanisms, 400 pulleys and almost 400 meterscable.
Because the observatory, with its 12 meters high and a shield equivalent to a tennis court, had to be folded to slip into the cap of Ariane 5."Encapsulage" was done with laser guidance to avoid damage to the instrument, whose development cost some ten billion dollars.
For these maneuvers, NASA also imposed draconian cleanliness measures to avoid any contamination of the telescope mirror, by particles or even loaded breath ...
Entry into service in June
Finally, a tailor -made depressurization system was installed by Arianespace so that the separation from the launcher, 120 km altitude, no brutal pressure of pressure is damaged the beast."A exceptional" customer ", exceptional measures," an ESA official in Kourou explained on Thursday.
This operation seals a little more cooperation between NASA and its European partners.For space, "strong cooperation is essential to achieve great things," said ESA and NASA officials in Kourou.
However, it will take several weeks to find out if the telescope is ready to operate.With an official entry into service scheduled for June.
Source: © 2021 AFP
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