NASA gets two military spy telescopes for astronomy - The Washington Post

1;2cIn article ,
Greg Goss wrote:
Fred J. McCall wrote:

That gives us a required aperture of around 7.66 meters to get "dime
sized resolution by military spy sats". That makes it around half
again as big as the absolute largest cargo diameter we have ever been
able to launch on anything other than a Saturn V.

Didn't one of the recent (or upcoming) astronomical scopes unfold
itself after reaching orbit?

Yes, JWST is intended to do so. And the fact that the unfolding
mirror wasn't regarded as the absolute greatest technical difficulty
of the project made it seem quite plausible (given also the Hubble
backstory) that NRO was using deployed mirrors already; moreover
there's http://www.navy.mil/submit/display.asp?story_id=51980 with a
segmented-mirror telescope made by Kodak and shipped to NPS because
NRO had no further use for it.

JWST is specified for about a 150nm RMS surface error, which is
quarter-wave quality at the 600nm shortest wavelength that its
instruments detect. But the JWST mirror segments have seven actuators
and the SMT ones have 'more than 100'; that degree of active surface
control sounds to me like what would be required for optical surface
quality. Note too
http://www.stsci.edu/stsci/meetings/...yMatthews1.pdf which
is a Kodak paper from 2003 describing a mostly-finished lightweight
actuated segmented mirror project.

JWST as an infra-red telescope at the L2 point has all sorts of
cryonics issues which a telescope designed for use from low Earth
orbit in the optical regime would not have to worry about; looking at
scenes illuminated by sunlight or by endogenous heat is a rather
different regime to looking at very distant galaxies.

(a human might be outputting about 100 watts at 250 kilometres; an
active galactic nucleus outputs about 10^33 watts at 250 megaparsecs
which is the equivalent of _one microwatt_ at 250 kilometres)

I would be unsurprised if the NRO used multi-metre unfolding
telescopes in Earth orbit at present; though I suspect it will be
thirty or more years before they release the relevant documents, and
it could be that the whole thing was part of the famously-disastrous
Future Imagery Architecture project and it never actually worked.

Tom