James Webb Telescope: from takeoff to the first images, we tell you about the four stages that await the space mission



Thirty two years. This is the number of years that elapsed between the idea of ​​building this ultra-powerful telescope in 1989 and its final launch into space, scheduled for Saturday, December 25, barring new unforeseen events. The James Webb Telescope (JWST), named after a former NASA executive, is touted as the successor to the Hubble Telescope. He must explore with unparalleled precision all phases of the cosmos, right down to the first ages of the universe and the formation of the first galaxies.

A more than ambitious challenge for this latest generation space observation tool which will be placed in orbit around the Sun, 1.5 million kilometers from the Earth. The fruit of 40 million hours of work carried out by 14 countries, this little technological gem, sometimes considered too expensive, almost remained in the pipeline, as reported by TV5 Monde.

Its launch has also been postponed several times, whether for technical or meteorological reasons. No bigger than a private plane, it must finally take off on Christmas day between 1:20 p.m. and 1:52 p.m. from the base of Kourou, in Guyana, powered by the Ariane 5 rocket. A look back at the four stages of this titanic project.

1A take-off that has been delayed several times

Will it really take off one day? This is the question that ended up asking, a little annoyed, the American, European and Canadian scientists who have been working for more than 30 years on putting it into orbit. In 2011, the first grain of sand: the American Congress announced its wish to no longer participate in the financing of this project estimated at 10 billion euros and the cost of which has tripled in a few years. But thanks to the mobilization of astrophysicists, this revolutionary telescope was barely saved.

The recent transport by boat of the telescope from Cafornie to Kourou was not easy either, according to Daniel de Chambure, engineer and responsible for adapting Ariane 5 for the mission, cited by 20 minutes. Its 10,000 km journey, passing through the Panama Canal, the telescope passed it in a container specially designed to protect it from any contamination. The goal? Above all, do not harm the quality of its future observations.

Other twists and turns will then delay the takeoff of the aircraft. Despite successive postponements in March and September 2021, it was at the end of December that the Arianespace space agency wanted to stop its orbiting schedule. First scheduled for December 18, then postponed to 22 after an incident during preparations for takeoff, it was finally for the 24th that the launch was confirmed. The reason for this new postponement? One “communication problem between the observatory and the launch system”, according to the Arianespace Twitter account. Finally, “from adverse weather conditions “ forced the space agency to shift again “Flight VA256 intended to launch the James Webb Space Telescope” to Saturday 25 December.

2A puzzle to enter Ariane 5

Perhaps the most colossal challenge of this project was to be able to fit the telescope into the fairing of the Ariane 5 rocket. Too large with its 6.5 m mirror, it was necessary to develop a mirror that folds up, stored in the launcher like an origami. For this, the The multibillion-euro telescope therefore found itself suspended from a cable 40 m high before being delicately placed up to the top of the rocket.

James Webb, who will have a vision a hundred times more precise than his predecessor Hubble, is also composed 18 smaller hexagonal mirrors covered with gold to better reflect light in space. A huge sun visor made up of five layers protects the mirror and all observation instruments. Constructed of kapton, this sun visor must withstand extreme temperatures near the sun.

3 A journey of 1.5 million kilometers

It will take a month for the James Webb telescope to reach its destination, and the space mission will last between five and ten years. The space telescope will orbit the Sun, in a stable and almost unknown place in the universe: “The Lagrange point L2”, located 1.5 million kilometers from Earth. At this distance, and thanks to his infrared technology, James Webb will have three major missions.

The first will be observe the formation of the first galaxies, until the Big Bang, 13.8 billion years ago. The second will be to accelerate the study of exoplanets to ddetermine the composition of their atmosphere, their cloud, and detect the possible presence of water. Finally, the telescope will be responsible for studying the mystery of the formation of giant black holes and observe beyond the orbit of Neptune to better understand the formation of the solar system.

4 First images in June 2022?

After the launch from the Guyanese base at Kourou on December 25 and the mandatory separation of the telescope from the rocket for about thirty minutes, it will take about fifteen days for James Webb to deploy his heat shield. In total, over 200 mechanisms must be activated during this time for full deployment.

Once this delicate operation has been carried out, the 6.5-tonne telescope will travel a further fifteen days before finally reaching its parking area at the point of Lagrange L2. It will then be necessary calibrate the telescope and its observation instruments so that it is in a position to function optimally.

This phase is expected to last five months. If everything goes as scientists have imagined, the first usable data will therefore arrive no earlier than June 2022.



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