Mirrors...

I was just at a talk at the Space Telescope Institute
that described a telescope that would be suspended
from a balloon over the South Pole. There was no one
mirror. It was a composite of 10 smaller mirrors that
were layed out over a grid. They did all sorts of studies
on the harmonics. 

It was not clear to me, though, that the array could be
folded up. I'm sure that they needed very careful alignment. 

-Peter