Limits to telescope size

(Henry Spencer) :

In article .com,
wrote:
How about this: putting 3 or 4 Hubble-sized (for redundancy & time-use
issues) craft in Jovian Trojan orbits would give you a 10 1/2
AU-equivalent instrument! That would almost see planets in Andromeda!

Only if you could hold the distance between them stable to within a
fraction of a wavelength of light, *and* beam the light gathered by one
to another across that distance without losing much of it. That...
presents problems, to put it mildly.

People are still struggling to make imaging interferometry work well at
distances of a hundred *meters* with both telescopes resting on solid rock.

Henry, correct me if I am wrong. But I thought with present day computers
you don't need to hold the distance steady between the scopes. Rather you
needed to know the distance to a fraction of a wavelenght between the scopes
at the time the signals are recorded.

I seem to remember that this has already been done with radio telescopes on
earth where two telescopes used a single atomic clock to timestamp the
recording.

Opps, just realized with long radiowaves even the phase shift can be measured
- if you need the phase of visible light to be recorded at both scopes at the
same time I don't think we have reach that tech yet.

Earl Colby Pottinger

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