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Everyone knows of the issues the Hubble had with its primary mirror.
But could a space telescope be created that used a reflective material such as Mylar or other very reflective material?

Would it be possible to design a camera system that could compensate for the "rough" surface? Would such a telescope a telescope be able to peer at "close" object such as planets out to let's say 50 ly?

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  • $\begingroup$ I am not sure soft materials can maintain lambda/20 flatness over a very wide area. Using adaptive optics to compensate for the surface roughness would be costly in space. $\endgroup$
    – wcc
    Jun 18, 2019 at 14:17
  • $\begingroup$ Wasn’t there a spare primary mirror made that was perfect and kept in storage, but a political decision put the poor one up there due to keeping a "name" happy... $\endgroup$
    – user207455
    Jun 18, 2019 at 14:40
  • $\begingroup$ @SolarMike - there was a second camera not mirror. But it was identical to the original. The second camera was what was used to fix part of the distortion in Hubble. $\endgroup$
    – Rick
    Jun 18, 2019 at 14:45
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    $\begingroup$ @Rick So this is the mirror you say does not exist : airandspace.si.edu/collection-objects/… $\endgroup$
    – user207455
    Jun 18, 2019 at 14:49
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    $\begingroup$ And just for info : newscientist.com/article/… $\endgroup$
    – user207455
    Jun 18, 2019 at 14:51

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This seems to me to be how adaptive optics works, and people do indeed do this. I suspect that using a mirror made from some very light material like mylar would be problematic as it would be too hard to keep track of what shape the mirror actually was at any given moment, but telescopes certainly adapt the effective shape of their mirrors in real time to compensate for things like atmospheric conditions and deformation of the mirror as it points in different directions. As a comment said this might be expensive both in terms of power and having to lift the thing for a space telescope.

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  • $\begingroup$ Would the "mirror" change that much in space? especially if it was opened on a frame that was locked in place? $\endgroup$
    – Rick
    Jun 18, 2019 at 14:43
  • $\begingroup$ @Rick: that depends on how thermally-stable the whole thing is I suppose. But unless you know the shape of it in advance you still have to do all the work to compensate for its shape on the spacecraft: you just only have to do it once. $\endgroup$
    – user107153
    Jun 18, 2019 at 14:59
  • $\begingroup$ I was thinking of of a satellite that opened like a fan, but was very light, yet rigid. Something that could be very large in diameter. But able to focus onto a single point $\endgroup$
    – Rick
    Jun 18, 2019 at 17:33
  • $\begingroup$ @Rick: 'Very light, yet rigid', along with 'very light but repeatably accurate to tens of nanometers across a large surface when unfolded' is not a trivial engineering problem. $\endgroup$
    – user107153
    Jun 18, 2019 at 17:57
  • $\begingroup$ does it have to be an extreme engineering problem if you are trying to see items very close (within 50-100 ly). I am not discussing seeing things very far and very small. $\endgroup$
    – Rick
    Jun 18, 2019 at 23:05

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