Like in the title. With E-ELT we are pushing the limit of what we can build on the ground. With JWST we are pushing the limit of what can we launch into space.

So instead, why don't we launch tools and materials to build a telescope and polish its mirror in orbit? This has several benefits. The environment is vacuum and microgravity, so very large components can be moved with small and light tools. The structure can be very light and fragile, bacause it doesn't have to survive the launch. It can be huge, because it doesn't have to fit into a rocket. Errors can corrected before it is commisioned.

I am sure, I'm not the first one to have this idea, but I failed to find any existing projects (upcoming or future) on the web. Do you know any such projects being considered?

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    $\begingroup$ It takes more than 1000 people to build a telescope like JWST, not to mention all the facilities needed for the construction... $\endgroup$
    – Pulsar
    Aug 13, 2013 at 9:24
  • $\begingroup$ I am not saying it would be easy. But i was wondering how to build something as large or larger than E-ELT and put that into space. It seems, that the best way to go would be to build it in space. I assume the cost would be greater than building the ISS. I am only asking if there are any existing proposals of such a project. I am not saying it has to be comissioned in the next 5 years. It can be for year 2050 or even 2100. Are any people (scientists and engineers) even considering such a project? $\endgroup$
    – Eiver
    Aug 13, 2013 at 9:31
  • $\begingroup$ My advisor once informed me that there were plans for building a telescope on the "dark" side of the moon, but were nothing beyond that: plans on paper $\endgroup$
    – Kyle Kanos
    Aug 13, 2013 at 11:25

2 Answers 2


For the optical wavelengths that are not absorbed by earth's atmosphere, there is hardly a need for space-based telescopes. We can build football-field-size optics, if we want. The enabling technology is adaptive optics which successfully combats the image degrading effects of atmospheric turbulence.

  • $\begingroup$ OWL looks very interesting. This is an example of a concept I was asking for, though it is ground based. Still, building such huge structures on ground is challenging from an engineering point of view. They even have to take wind into consideration. Majority of mass is used support the whole thing. In space a telescope of this size could be much less massive and simpler (no adaptive optics), but still the material would have to be brought to LEO (expensive). I still wonder at which point it would be advantageous to build in space. $\endgroup$
    – Eiver
    Aug 14, 2013 at 7:10

Space based manufacturing was something of a dream of 50's and 60's sci-fi writers.

Unfortunately the huge setup costs are enough to put anyone off trying this other than billionaire speculators (Planetary Resources).

The infrasctructure to build JWST spans several continents and budgets, admittedly it is one of the more expensive projects. But even so the fine measurement and correction carried out in manufacture would require massive investment in buildings and people (c. 1000 people maybe?).

A more realistic approach to emulate the resolution of 40m-100m dishes is through interferometry, ie many smaller sattelites flown at large seperations etc.


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