in pictures | Successful launch of the James Webb Space Telescope

The James Webb Space Telescope (JWST), which astronomers around the world have waited for thirty years to examine the universe in unparalleled means, blasted off an Ariane 5 rocket on Saturday to reach its observation point, 1.5 million kilometers from Earth.

We’ll know 27 minutes after take-off if the propulsive phase of the flight went well.

With liftoff from Guyanese Space Center on time at 12:20 GMT, JWST will become the most advanced universe-monitoring instrument ever sent into space. But it will take another 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?”.

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.

Envisioned by NASA since Hubble launched in 1990, and built from 2004, in collaboration with the European Space Agency (ESA) and Canada (CSA), the JWST differs in more than one way.

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.

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…

Finally, a specially designed aerodynamic decompression system was installed by Arianespace so that, when separated from the actuator, at an altitude of 120 km, a sudden change in pressure would not damage the beast. “For an exceptional customer, exceptional measures,” an ESA official in Kourou explained on Thursday.

It will take several weeks to see if the telescope is ready for use. With formal entry into service scheduled for June.