NASA says James Webb Space Telescope passed critical sunshield test

Ahead of its planned 2021 launch, the James Webb Space Telescope has passed a new critical test, according to NASA. All five layers of the telescope's sunshields were completely deployed and tensioned last week, meaning the sunshield is now installed in the same way it will be when the James Webb telescope is in space. This is the first time the sunshield has been deployed in this way and the result is described as "stunning."

The James Webb telescope packs a huge number of technologies that will enable it to eventually observe parts of the universe humanity hasn't yet studied. One of those technologies is the five-layer sunshield, which — as its name suggests — is designed to protect the telescope's sensitive components from the Sun's heat and light.

In order to ensure the machine's sensor and optics stay cold enough to operate as intended, the James Webb telescope will need to successfully deploy the sunshield after it launches, meaning tests on Earth are necessary to make sure everything will go as planned. The Webb team was tasked with testing the deployment and subsequent tensioning of each of the five sunshield layers, according to NASA.

Each of these layers are made from Kapton, a polymer material coated with aluminum, NASA explains. This coating is designed to reflect heat away from the optics and sensors, something joined by a treated silicon coating on the two layers that'll be most exposed to the Sun's ultraviolet radiation.

Ultimately, NASA says this sunshield has a wingspan equivalent to a full tennis court despite the fact that it can be packed into a rocket payload fairing that measures 16ft in diameter. Now that the deployment test is complete, the Webb team has been tasked with folding the sunshield into this compact, stowed position so that additional tests can take place.