The corresponding space telescope for exoplanet detection and spectral characterization is being planned for sooner than you may expect: https://www.jpl.nasa.gov/habex/.
This, or a similar concept, is hoped to be in the upcoming National Research Council decadal survey which recommends astronomical priorities for the 2020s. Current designs require as little as 4 meters.
Stability is one advantage of space telescopes. Integration times for spectral characterization can run into days.
Promising developments, but christ, could they move any slower?!
We know what technology we need to build. Why must we wait a full two more years for a report to get finished before even beginning funding proposals on which path to pursue, before beginning any construction or engineering?!
None of us are getting any younger. I know this is complicated technology to build, but contrast how fast technology moves in the valley compared to this, and you can see the ways in which NASA could really use a bit of startup hustle... (like back in the 60's, when NASA engineered and landed people to the moon within a decade.) There just appears to be no sense of urgency at all.
I don't have time to reply to this with the level of detail required, but I'll just say that you underestimate the level of tech needed to deploy a mirror this good, and you overestimate how much we understand the instrument design issues. That is, we don't know what to build.
The trade studies are highly complex (how big the aperture is, how long the mission is, how much propellant is needed to slew the spacecraft, what the yield will be in terms of number of spectral characterizations, whether you need an external star shade). The star shade, if needed, would be a separate spacecraft.
General comparisons to "how fast technology moves in the valley" are not specific enough to benchmark what's needed for this rather unique mission.
When money is tight, those in charge of allocations get more beaurocratic, thus wasting more money.
It would be fun to see part of NASA run on design/execution challenges. Have 5000 postdocs on salary, then offer a ($1B-X) bonus for the team which designs and launches a space telescope for X.
This, or a similar concept, is hoped to be in the upcoming National Research Council decadal survey which recommends astronomical priorities for the 2020s. Current designs require as little as 4 meters.
Stability is one advantage of space telescopes. Integration times for spectral characterization can run into days.