The perilous deployment in space of the James Webb telescope, which ended on Saturday with its main mirror, is “100% successful,” said NASA, celebrating a feat that brings the observatory a little closer to the beginning of his exploration of the cosmos, in five and a half months.
“I am so moved,” said live from the control center Thomas Zurbuchen, head of science missions at NASA, the US space agency. We have a telescope deployed in orbit! “
The telescope’s iconic primary mirror measures around 6.5 meters in diameter, so it was too large to fit into a rocket when it took off two weeks ago. Its two sides must therefore have been folded back.
The first of these two wings was deployed on Friday, and the second opened on Saturday morning, as planned. The space agency teams then spent several hours locking it in place, in order to secure it permanently.
The operation was piloted from the Space Telescope Science Institute, located in Baltimore, on the US East Coast. Dozens of engineers exploded with joy once this last step was confirmed, according to images broadcast live.
NASA boss Bill Nelson then spoke via video link: “What a great day,” he said, visibly very moved. NASA is a place where the impossible becomes possible. “
The deployment in space of an object of this magnitude, not only its mirrors but also its heat shield earlier this week, had never been attempted in the past.
“We can confirm that the deployments that have just taken place have been 100% successful,” John Durning, deputy project manager for James Webb, told a press conference on Saturday.
Astronomers around the world, who will use this space observatory, can thus breathe a big sigh of relief, the mission now appearing to be on the right track for success.
“The last two weeks have been great,” said Project Manager Bill Ochs. “That was probably the highest risk part of the mission, but that doesn’t mean all risk goes away.”
Before being operational, the telescope will still have to reach its final orbit, 1.5 million kilometers from Earth, in two weeks (it is already more than a million kilometers away).
Each of the 18 hexagonal segments forming this huge primary mirror – coated in gold to better reflect light – will also need to be carefully adjusted. A process which will begin in the coming days and will take three months.
Scientific instruments will have to continue to cool, and be very precisely calibrated.
Edge of the Universe
The first images will be made public at the end of the commissioning period, in the summer, six months after take-off.
The most powerful space observatory ever designed, James Webb must notably make it possible to observe the first galaxies, formed only about 200 million years after the Big Bang.
It must also take a big step in the exploration of exoplanets, orbiting stars other than the Sun. He will examine their atmosphere, in search of conditions conducive to the appearance of life.
Also planned are closer observations, in our solar system, of Mars or Europe, a moon of Jupiter.
To detect the faint gleams from the far reaches of the universe, James Webb needed a main mirror larger than any sent into orbit so far.
The secondary mirror, much smaller and placed at the end of a tripod in front of the main mirror, had been successfully deployed on Wednesday. It is used to focus the light from the primary mirror, before directing it to a third mirror and the four scientific instruments.
On Tuesday, the mission had reached a major milestone with the most difficult deployment, that of the heat shield.
Composed of five layers each the size of a tennis court, but as thin as a hair, this sun visor protects scientific instruments from the heat of our star.
The face closest to the Sun can reach 125 ° C, and the furthest away -235 ° C.
The great novelty of this telescope is that it will operate only in the near and mid infrared (wavelengths invisible to the naked eye), and its instruments can therefore only operate in total darkness and at temperatures extremely low.
James Webb, worth some $ 10 billion, is expected to operate for at least 5 years, and potentially up to 10 years.
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