Interferometry
How about making 2 separate telescopes
behave as though they were 2 pieces of one much larger telescope. You get the
larger one’s resolution, but not its light-gathering power. The light from
the units
Must be combined “in phase” (preserving the character it
would have
had if it came off the same larger mirror). This is easy at radio wavelengths, but
hard
at optical wavelengths.