Results 1 to 7 of 7

Thread: A 100-Meter Rotating Liquid Mirror Telescope on the Moon? Yes Please.

  1. #1
    Join Date
    Jul 2003
    Posts
    29,088

    A 100-Meter Rotating Liquid Mirror Telescope on the Moon? Yes Please.

    A team from UT Austin has renewed a proposal for a liquid-mirror telescope on the Moon that could study the first stars in the Universe.
    The post A 100-Meter Rotating Liquid Mirror Telescope on the Moon? Yes Please. appeared first on Universe Today.


    More...

  2. #2
    Join Date
    Dec 2001
    Posts
    100
    What would be the challenges involved in keeping the liquid Mercury isolated from moon dust due to it's highly conductive properties?

  3. #3
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    9,256
    Some early reflectors used rotating liquid metal such as brass or bronze. They had to be manually polished regularly to remove the oxides . I note the mercury is floating, I wonder what on? For weight I would prefer a aluminised mylar mirror with an electrostatic grid beneath to create and adjust the parabola. That is to adjust it from a catenary. Or an approximate plastic parabola with a thin liquid spinning. Resin is another possibility because on the moon you could sputter aluminium “easily” thanks to the vacuum. Dust is a problem, I think. But maybe a simple high fence all round would be enough. Another more exotic suggestion is to use an electron gun to create a fresnel mirror on a plastic sheet, melt it and metalise it. This can be remade many times with adjusted light frequencies. The gun is where the focus tower has to be.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  4. #4
    Join Date
    Jun 2007
    Posts
    5,921
    ...no thanks?

    Why do people keep thinking this kind of thing is a good idea? This telescope would only be able to observe a thin strip of the sky. Its field of view will sweep along that strip, taking about a month to complete a circuit as the moon rotates. It will be subject to extreme temperature swings. It will have to endure two week long nights with no solar power. It will be exposed to abrasive and mobile moon dust. And you could have a whole fleet of orbital telescopes for what it'd cost to land all the materials and construct it on the surface of the moon. Every ton of propellant spent landing materials/personnel on the moon is a ton of orbital telescope you sacrificed to do so.

  5. #5
    Join Date
    Mar 2004
    Posts
    19,317
    I’m wondering why not spin it in sunlight and then shade it to freeze it? After that, why not keep it shaded and cool so it stays frozen and can be tilted? But yeah, multi-segment mirrors are getting easier to make too, so a space based hundred meter scope probably makes more sense. Easier to work the other optics too in microgravity.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  6. #6
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    9,256
    Quote Originally Posted by cjameshuff View Post
    ...no thanks?

    Why do people keep thinking this kind of thing is a good idea? This telescope would only be able to observe a thin strip of the sky. Its field of view will sweep along that strip, taking about a month to complete a circuit as the moon rotates. It will be subject to extreme temperature swings. It will have to endure two week long nights with no solar power. It will be exposed to abrasive and mobile moon dust. And you could have a whole fleet of orbital telescopes for what it'd cost to land all the materials and construct it on the surface of the moon. Every ton of propellant spent landing materials/personnel on the moon is a ton of orbital telescope you sacrificed to do so.
    Exactly why a light mylar mirror is preferable. It can not only be a simple parabola it can be directed by its electrostatic sandwich, even scanned in a raster. It can be a distributed array too, modular design, rather like putting up tents. Shipping mercury to the moon? As to why, well like all telescopes, why look?
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  7. #7
    Join Date
    Jun 2007
    Posts
    5,921
    Quote Originally Posted by Van Rijn View Post
    I’m wondering why not spin it in sunlight and then shade it to freeze it? After that, why not keep it shaded and cool so it stays frozen and can be tilted? But yeah, multi-segment mirrors are getting easier to make too, so a space based hundred meter scope probably makes more sense. Easier to work the other optics too in microgravity.
    There's typically a big volume change on solidification in metals, and the formation of crystals might affect the surface finish. You'd need to grind and polish it to get back to the correct shape and finish. If you're going to do that, there's better ways of roughly shaping a reflector.

    Another advantage of a solid mirror is that it can be coated with a metal chosen for its optical properties, rather than making do with the extremely limited selection of metals with very low melting points. And you can actually cool the reflector for far infrared astronomy.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •