You are looking at the largest piece of tin foil in the planet, one of the James Webb Space Telescope's sunshield membranes. There will be five of these membranes, which will keep its core at 50 Kelvin (-369.67F or -223.15C).
The sunshield is a new technology concept developed specifically for the Webb. It's actually made of a material called Kapton, a polyimide film developed by DuPont. Kapton's structure remains stable going from 0 to 673 Kelvin (−459 to 752F or −273 to +400C) and, for this sunshield, it has been coated with aluminium and doped-silicon. The coating will reflect the Sun and Earth's heat back into space, keeping the heart of the telescope cool.
According to NASA, each of these "five layers has to be precisely spaced with respect to the next." It's going to be excited to see the Webb in space. Not only because it's going to see further into the past than any other telescope in existence, but also because it's such an amazing technology feat. I still can't believe this giant ship is going to be launched in a tiny capsule on top of an Ariane 5 rocket in 2018. [Flickr]