Loren Pechtel wrote:You lose most of the energy due to dispersion, not due to the atmosphere.
Fair enough, but if they can have effective laser and graser weapons at hundreds of thousands of km, bouncing low-power lasers and getting a few photons back should be easy. As I said, we're doing it right now. And unlike the EHT, those ships would all have line-of-sight to make perfect measurements.
And before its collapse, the Arecibo Observatory was also a transmitter, allowing us to have not only radio astronomy, but radar astronomy. The resolution was horrible, but photons in the radio frequency travel as fast as those in the X-ray range, so for ranging (the second R in RADAR) it was more than enough.
I wouldn't be surprised to find out that VLBI is exactly how those massive arrays detecting hyper signals in Manticore are built. Which in turn means that now that they have FTL signalling, the Manticore-built arrays might be even better than everyone else's.