Deployable mirrors

What's the current state of the art in deployable mirrors? I know NGST's
mirror is to be deployable via two folds:

\ /
\ /
\________/

but I remember reading during the period when the NGST proposals were
being decided on about systems which would deploy several petals
around the outside of a central mirror.

Is the plan to launch NGST without a preliminary "can we actually
deploy mirrors in space" Discovery-class mission?

I suppose it's not realistic to expect much public information about
the development of a technology whose major (in cost of procured
items) application will be at the National Reconnaissance Office, with
astronomical missions coming a distant second.

Tom

Thomas Womack wrote:
What's the current state of the art in deployable mirrors? I know NGST's
mirror is to be deployable via two folds:

\ /
\ /
\________/

but I remember reading during the period when the NGST proposals were
being decided on about systems which would deploy several petals
around the outside of a central mirror.

Is the plan to launch NGST without a preliminary "can we actually
deploy mirrors in space" Discovery-class mission?

That used to be the plan (NEXUS mission) but this precursor
has now vanished into cost control. Scuttlebutt has it that the
technique has been demonstrated for longer-wavelength optics for,
umm, agencies whose acronyms aren't supposed to be widely known...

Bill Keel