Rigidized polymers appear to be a feasible technology to create space telescopes larger than kilometer sizes. It should be possible to make 50 meter space telescope elements in 1000 kilometer baseline space telescope arrays.
The Event Horizon Telescope at 1.3 millimeter wavelength achieved 25 microarcsecond resolution on M87.
Many 50-meter space telescopes in a 1000 kilometer baseline array would 100 times better with 245 nanoarcsecond resolution using 1 micron wavelengths.
Making arrays of 40 or 50-meter space telescopes over a 1000 kilometer baseline would be better for imaging exo-earths (earth planets in other solar systems) and blackholes. They would also likely be cheaper to make than a kilometer space telescope.
The 1000 kilometer baseline arrays would have over 400,000 times the light collection of the Hubble Space telescope.
The six image above show the increases in image quality so that we can go from binary stars being a single point of light to seeing the two stars as separate points and then to more and more detail of the surface of the star.
50-meter space telescopes should be easily made from mylar inflation. Mylar inflation likely tops out at 100-meter space telescopes.
Larger monolithic inflated UV-cured solid apertures are theoretically possible up to 100 kilometers in size but we will need more space launch capabilities. They could be built after we have fully rapidly reusable launch capability.
Phased arrays of apertures are unlimited in aperture size.
They have a design with two concentric spheres and other optics to get diffraction limited space telescopes. Diffraction limited space telescopes are the resolution limit of regular physics.
There have been other work to exceed the diffraction limit but those have not been developed with this kind of size scaling. The diffraction limit designs are only for the large monolith space telescopes.
The telescope arrays are light buckets and do not try to push for the diffraction limit. They will be used for different kinds of imaging.