Miroir primaire de Webb

The James Webb Space Telescope has finished deploying its solar shield, now it’s time for mirrors

It’s done, the James Webb Space Telescope has successfully completed the operation that NASA officials had described as more complex and delicate. The 5-layer solar shield was able to be fully stretched on Tuesday, January 4, and the team can now focus on the next stage of deploying the $ 10 billion telescope.

The next step in setting up the space observatory is the configuration of the primary and secondary mirrors. On the evening of January 4, NASA officials indicated that the deployment of the mirrors would begin with that of the secondary mirror, and that this event would take place on the morning of Wednesday, January 5. However, the agency later announced during a press conference that the deployment is unlikely to take place for a few days.

According to Alphonso Stewart, Webb’s first deployment manager at NASA’s Goddard Space Flight Center, the process will likely begin by the weekend. He said that the operation to install the two mirrors will take around 10 days.

Webb’s mirrors

Webb is equipped with a primary mirror made up of 18 hexagonal segments. At the moment, this mirror is folded at its two sides, but after unfolding it will be 6.5 m wide. According to information, it was necessary to bend the “wings” of the mirror so that it could be placed inside the fairing of the Ariane 5 rocket.

As for the secondary mirror, it is the second surface where the light will arrive before reaching the four scientific instruments of the telescope. The secondary mirror, which measures 0.74 m, is placed opposite the primary mirror. It is held by rods which will also need to be deployed.

The installation of the secondary mirror will be done before that of the primary mirror. According to Stewart, this operation will be preceded by the preheating of the engines which will be used during the process.

The importance of the solar shield

During his time in space, Webb will be tasked with detecting very weak heat signals coming from the early Universe. For this, mirrors and instruments must remain at an extremely low temperature. This is the reason why the solar shield is so large with its size similar to that of a tennis court. Webb’s position in space, orbiting the second Lagrange point L2, will also allow it to remain aligned with the Earth, the Sun and the Moon. This will allow the solar shield to continuously block the light and heat from these objects.

After arriving at his destination, Webb will not be able to start working straight away. NASA technicians will still need to align the 18 segments of the primary mirror very precisely to function as a single block. Measuring instruments will also need to be calibrated.

According to NASA, it will take several more months before all preparation operations are completed. However, this is nothing compared to all the expected results.

SOURCE: Space.com

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