<p>I suppose that (especially space) telescope costs is dominated by design and development, not by material and manufacturing. So once a telescope has been developed and designed, how much extra would it cost to build a second copy of it? It seems as if spy satellites are built in batches of similar designs.</p>

<p>Would the science value of a second similar telescope be modest, compared to a unique instrument, or improvements on the single telescope, for the same cost?</p>

<p>I suppose that using two telescopes as an interferometer would be quite a different instrument design to begin with than just two of the same.</p>

CC BY-SA 3.0
2016-04-26T08:47:03.400Z
Not an answer, but related:   http://www.atlasobscura.com/places/large-binocular-telescope
userLTK
CC BY-SA 4.0
2019-01-29T15:33:16.837Z
It depends if there are any limitations on the observational parameters of the first, that a second one could lift. Simple example: The HARPS instrument can only observe on the southern hemisphere, so HARPS-North was built. Otherwise it would be hard to justify against just observing longer with only one scope/instrument.
AtmosphericPrisonEscape
CC BY-SA 4.0
2019-02-02T22:24:44.097Z
@userLTK "Today the telescope is busy taking **stereoscopic** images of spiral galaxies, the crab nebula..." It isn't really doing that is it? If so I'd expect Brian May to be all over it! I'd asked [What are the raisons d'être for the Large Binocular Telescope “binocularity”?](https://astronomy.stackexchange.com/q/24163/7982) earlier because I don't really understand the choice of that configuration.
uhoh
CC BY-SA 4.0
2020-11-22T22:47:35.027Z
Well, with two identical telescopes, even sitting next to each other, you can observe two objects at the same time, so twice as many observation programs…
Pierre Paquette
<telescope><space-telescope>
What is the cost and benefit of building two identical telescopes?
LocalFluff
# What is the cost and benefit of building two identical telescopes?

(Asked by: username_0 on 2015-10-16)

I suppose that (especially space) telescope costs is dominated by design and development, not by material and manufacturing. So once a telescope has been developed and designed, how much extra would it cost to build a second copy of it? It seems as if spy satellites are built in batches of similar designs.

Would the science value of a second similar telescope be modest, compared to a unique instrument, or improvements on the single telescope, for the same cost?

I suppose that using two telescopes as an interferometer would be quite a different instrument design to begin with than just two of the same.

**Tags:** telescope, space-telescope

> **Comments:**
> **username_1**: Not an answer, but related:   http://www.atlasobscura.com/places/large-binocular-telescope  
> **username_2**: It depends if there are any limitations on the observational parameters of the first, that a second one could lift. Simple example: The HARPS instrument can only observe on the southern hemisphere, so HARPS-North was built. Otherwise it would be hard to justify against just observing longer with only one scope/instrument.  
> **username_3**: @username_1 "Today the telescope is busy taking **stereoscopic** images of spiral galaxies, the crab nebula..." It isn't really doing that is it? If so I'd expect Brian May to be all over it! I'd asked [What are the raisons d'être for the Large Binocular Telescope “binocularity”?](https://astronomy.stackexchange.com/q/24163/7982) earlier because I don't really understand the choice of that configuration.  
> **username_4**: Well, with two identical telescopes, even sitting next to each other, you can observe two objects at the same time, so twice as many observation programs…  

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## 0 answers

