I'm passingly familiar with the old Keyhole/Hubble optical satellites, but I didn't think we launched any of those recently after the Shuttle shut down. The more interesting tech is probably sigint-targeted radio analysis, where antenna and LNA design is more important than physical aperture, I wouldn't be able to tell anything about those with a physical dimension. What would the new satellites launch on?
NRO Orion sats are probably the largest antennas ever in space (100m).
"These satellites at geostationary orbits collect radio emissions (SIGINT) and act as replacements for the older constellation of Magnum satellites. The satellites have estimated mass close to 5,200 kg and very large (estimated 100 m diameter) radio reflecting dishes."
