This sun visor is made up of five layers each the size of a tennis court, intended to protect scientific instruments from the heat of our star.
They have been carefully unfolded and stretched one by one since Monday.
Too large to fit into a rocket, the telescope had to be folded on itself like an origami and requires deployment into space, an ultra-perilous procedure.
Deploying this sunshade was one of the most difficult steps.
The most powerful space telescope ever designed, James Webb is awaited by astronomers around the world and must make it possible to observe in particular the first galaxies, formed only a few hundred million years after the Big Bang.
The observatory took off a little over a week ago from French Guiana and is currently over 900,000 kilometers from Earth.
It is still on its way to reach its final orbit, 1.5 million kilometers from us - four times the Earth-Moon distance.
In this place, in the event of a problem, no repair mission can be envisaged.
Its deployment, piloted from Baltimore, on the American east coast, must therefore be carried out without any missteps.
More than a hundred engineers are currently working there 24 hours a day to ensure that everything is going as planned.
Nasa broadcast the event live on the internet on Monday morning.
As there is no camera on board James Webb, the only images available were from the operations control room, where the deployment teams cheered with joy after the fifth layer power-up was announced.
© 2022 AFP