Webb sunshield fully deployed

The sunshield – about the size of a tennis court at full size – was folded to fit inside the Ariane 5 rocket’s nose cone prior to launch. The Webb team began remotely deploying the sunshield on 28 December 2021, three days after launch. The five-layered sunshield will protect the telescope from the light and heat of the Sun, Earth and Moon.

The unfolding occurred in the following order, over the course of eight days:

• two pallet structures – forward and aft – unfolded to bring the observatory to its full 21 m length;
• the Deployable Tower Assembly deployed to separate the telescope and instruments from the sunshield and the main body of the spacecraft, allowing room for the sunshield to fully deploy;
• the aft momentum flap and membrane covers were released and deployed;
• the mid-booms deployed, expanding perpendicular to the pallet structures and allowing the sunshield to extend to its full width of 14 m;
• finally, the sunshield was fully tensioned and secured into position, marking the completion of the sunshield deployment.

The unfolding and tensioning of the sunshield involved 139 of Webb’s 178 release mechanisms, 70 hinge assemblies, eight deployment motors, roughly 400 pulleys, and 90 individual cables totaling almost half a kilometre in length. The team also paused deployment operations for a day to work on optimising Webb’s power systems and tensioning motors, to ensure Webb was in prime condition before beginning the major work of sunshield tensioning.

The world’s largest and most complex space science observatory has another 5.5 months of setup still to come, including deployment of the secondary mirror and primary mirror wings, alignment of the telescope optics, and calibration of the science instruments. After that, Webb will deliver its first images.

The telescope’s revolutionary technology will explore every phase of cosmic history – from within our Solar System to the most distant observable galaxies in the early Universe, to everything in between. Webb will reveal new and unexpected discoveries and help humankind understand the origins of the Universe and our place in it.

Read more in the NASA release.

Webb is the largest, most powerful telescope ever launched into space. As part of an international collaboration agreement, ESA has provided the telescope’s launch service using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and for the procurement of the launch service by Arianespace.

Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA).