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The step was crucial for this machine to 10 billion dollars, otherwise it would not have worked. However, there are still several steps to be taken before James Webb can take his first images.
This is arguably the most impressive part of the telescope: its enormous main mirror, a diameter of 6.5 meters covered with a thin film of gold. It’s so big it had to be folded in three to fit in the Ariane 5 rocket that launched it into space.
Two weeks following lift-off, it has just been fully deployed. Webb is now in its final form. He is not going to start his observations right away, however. The machine must now be calibrated. This mirror is, for example, composed of 18 hexagonal panels, each equipped with a small motor to adjust them individually.
► To read also: Space: the James Webb telescope has deployed its heat shield
First image in June
The required precision is astounding: 10,000 times thinner than the thickness of a hair. It is however essential for the whole to behave like a single mirror and to be able to take stock correctly.
The next few weeks will also be used to continue cooling the telescope. It should operate at temperatures between -266 and -240 degrees. Its various scientific instruments will also be switched on and adjusted. It is only following that that Webb can begin to observe the universe. The first image is expected in June.
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