Re: NASA being NASA :)
It's the only way to pack a 6.5m mirror into what was supposed to launch on a Delta4.
Above about 8m diameter it's tricky to make a single monolithic mirror so we've been building segmented ones since the early 90s.
The main problem with segmented mirrors at these IR wavelengths isn't aligning them - it's that you can see the glowing hot telescope floor through the gaps. Which is solved by putting it in space and keeping it very very cold.
The real achievement was doing the OSHA paperwork to get the Beryllium mirrors polished in California!
Biting the hand that feeds IT
