TED Conversations

Nik Cronin

This conversation is closed.

Would a large network of small telescopes equal one large telescope?

The proposal.... Form a network of hundreds of amateur astronomers around the world focusing on the same objects at the same time using CCD's and automatic tracking mounts . Locate each telescope precisely with a carrier-wave GPS hack and network the whole lot through some glorious alloy of SeaDragon and PhotoSynth to produce one huge, stable, composite image.

The question.... Have I totally misunderstood the physics of magnification?

Share:
  • Nov 7 2013: Synchronizing all the data would be a hell of a chore (different elevations, positions on the earth, atmospheric interference...), and while the data may be very comprehensive, it'll also be of a low quality (multiple bad images cannot be complied into a good image after all).

    I wouldn't recommend it.
  • Nov 11 2013: This is not my area but can small telescopes collect enough light to see far into the galaxy? Thought that was the reason for larger telescopes to concentrate light.
    • Nov 12 2013: I'm thinking small scopes may only catch a few photons from a dim object so it would not be visible; but when we stack hundreds of images together they all have a few photons at that position lifting the image out of the noise.

      Certainly the optics need to be good quality and the CCDs need to be sensitive, but if each image is n-mega pixels and we combine hundreds of them we get a massive data set that we can zoom in on.
  • thumb
    Nov 8 2013: Optical resolution is limited by "seeing" which is distortion of the image due to atmospheric effects. Observatories have complex computer controlled systems to clear the view. Without these an optical telescope any bigger than about a metre across the mirror is pointless as its theoretical resolution excedes the resolution possible through the atmosphere. That's why they build observatories on mountain tops. Less air to see through. It's also why Hubble is so good. No air to see through.
    • Nov 8 2013: Understood Peter, but isn't the processor here doing the same job as the lasers and adaptive optics that the big scopes use? Providing a fixed point so you know how to adjust your image. Plus this network would be strong in places like the Canaries, Chile etc giving stable images.
      • thumb
        Nov 10 2013: The problem is you can't compensate for the atmospheric effect as it will be different for each individual telescope. It's a bit like looking through a dirty window. You could use a computer to attempt to compensate but every window has different dirt. Combining two images just combines two sets of problems. One good image is easier to produce.
        • Nov 11 2013: I agree. at these sensitivities even a minute gust of wind or temp fluctuations and even gravity humidity ect would be impossible to account for the 'noise' for even one telescope through our atmosphere at these distances. I wonder if computing facts from say 4 Hubble telescopes could allow us to see further! though it is my understanding that the problem is not distance, but breadth. we can only scan tiny pinpoints in the sky at any one time
        • Nov 11 2013: Well perhaps we can copy the big boys and put up a laser. One spot (a few spots?), near the target, that everyone can pick up. Perhaps we can encode time information in the beam to give another level of accuracy.
          As I understand it the pro's use the laser to change the shape of the mirror itself rather than the image but surely the physics would translate?
          Distributed systems are standard in radio astronomy and surely Gamma rays etc. are even higher wavelengths than light?
      • thumb
        Nov 11 2013: Large networks of radio telescopes are possible because the long wavelengths used aren't affected by the atmosphere. Gamma ray observations are generally done in space as they interact heavily with the atmosphere.
        http://en.wikipedia.org/wiki/Fermi_Gamma-ray_Space_Telescope
        • Nov 12 2013: Hmm, see what you're saying re the Gamma rays Peter, what say you to the laser idea? We know it works for a single scope, sure the processing would be fearsome but we run a distributed computer network to handle it, a la SETI.
  • Nov 8 2013: Very tricky, the processing, as you say Nadav, but I'd be surprised if it couldn't be done.
    You would have position and elevation pretty accurately for each telescope and all the data from the tracking mounts; not too precise maybe but then you have your processor mapping hundreds of these images together and adjusting for best fit. Maybe this gives you error correction on your positions and a fix for the atmospheric turbulence, especially if you have some good telescopes in places with excellent seeing. These stable images could be reference points for the whole network.
    Maybe the big problem with the processing is adjusting for the optics of different telescope types, if everybody involved had to own the same type or the same model you'd be very limited.

    Will the individual images be low quality? Perhaps they're low magnification but high quality? Can we zoom-in on the data set instead?
    • Nov 8 2013: The imaging is low quality because you're proposing we utilize amateur astronomers utilizing telescopes you apparently have the budget to buy by the hundreds.

      Its usually better to have a single, good quality image using proper facilities and trained personnel than it is to have multiple angles of poor quality.
      • Nov 8 2013: Well Nadav I hope we don't have to buy them at all as there are so many telescopes already out there.

        I love a giant telescope as much as the next man but they cost a fortune, take decades to build, have huge running costs, are weather dependant and highly temperamental. Plus of course they can only look in one direction at a time and then only at night. Probably 70% of the time they're doing no useful work at all.