Engineers will deploy covers that will protect the Webb Telescope from the sun, earth and moon

With the James Webb Space Telescope navigating through space, NASA engineers are ready to take on the most difficult task – deploying the sun visors. The engineers released and rolled up the sunscreens that protected the thin layers when the telescope was launched.

Deploying the blankets, which took about an hour, required the team to electrically activate the trigger devices, execute commands to roll up the blankets into a hold position, and expose the sunshade membranes to the sun. space for the first time. With the covers now out, the next step will be to deploy the intermediate arms of the sun visor, before tensioning the sun visor.

The team completed on Thursday the deployment of the observatory’s rear swing flap that will help reduce fuel consumption, which engineers will need to use throughout Webb’s life, helping to maintain the focus of the observatory in orbit. “As the photons of sunlight hit the large area of ​​the sunshade, they will put pressure on the sunshade, and if not properly balanced, that solar pressure would cause the observatory to rotate which must be supported by its reaction wheels. The rear momentum flap will navigate the pressure of these photons, balancing the sun visor and keeping the observatory stable, ”NASA said in a blog update.

The lens hood protects the telescope from external sources of light and heat (such as the Sun, Earth, and Moon). (Photo: Nasa)


The James Webb Telescope was designed precisely to observe the first light just after the Big Bang, when our universe was created. To do this, it will observe the universe in infrared light by detecting the weakest signals from distant objects and galaxies. In order to be able to detect these weak heat signals, the telescope itself must be kept extremely cold.

The James Webb telescope’s sunshades separate the observatory into two phases, a hot side and a cold side. The five-layer lens hood prevents sunlight from interfering with the telescope’s sensitive instruments which operate at -223 degrees Celsius. The three tennis court-sized membranes will always be between the Sun / Earth / Moon and the telescope. It can be positioned this way because JWST will orbit the Sun 1.5 million kilometers from Earth.

NASA said that in addition to keeping the telescope cool, the sunshade will also provide a thermally stable environment for the spacecraft, which is essential to maintain proper alignment of the primary mirror segments.


The James Webb Telescope Sunshade is a complex and innovative feat of materials science and engineering. Made from a unique material, each of the five layers has a specific thickness and size, and they must be separated with precision in space. Made up of a material called Kapton, each layer is covered with aluminum, and the sun-facing side of the two hottest layers has silicon doped to reflect the sun’s heat back into space.

Nasa said Kapton is a polyimide film developed by DuPont in the late 1960s. It has high heat resistance and remains stable over a wide temperature range from minus 269 to plus 400 degrees Celsius. Designed as a kite around the telescope, “The shape and design also directs heat to the sides, around the perimeter, between layers. The heat generated by the Spacecraft bus at the “core” or center, is expelled between the membrane layers so that it cannot heat the optics. The fifth layer is mainly for the margin against blemishes, micro-meteoroid holes, ”said James Cooper, head of the James Webb Space Telescope’s sunshade.

The mirrors of the James Webb telescope folded like an origami. (Photo: Nasa)

Each layer is made of different thickness, layer 1 will face the sun and is only 0.05mm thick, while the other four layers are 0.025mm thick. The material of the sunshade shrinks as it gets colder and the warmer layers expand.

Once the sunshade is deployed, engineers will focus on stretching the mirrors, which have been folded like origami to fit the fairing of the Ariane-5 rocket.

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