Rom & Matt - I agree entirely: what a piece of engineering (let alone manufacturing techniques)!
That the (
very) gradual solidification of the initially molten glass takes a whole year astounds me.
Given that typical glasses liquify around 1500 deg. C, the cool-down rate (over 12 months) is approx. 4 deg. C per day - and each component mirror does so while being constantly spun to form the parabolic reflecting surface
https://en.wikipedia.org/wiki/Glass.
BIG stuff!
Dean