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Cold War Spoils: Amateur Builds Telescope With 70-Inch Lens 101

Posted by timothy
from the just-winging-it dept.
First time accepted submitter 192_kbps writes "Mike Clements, a long-haul trucker from West Jordan, Utah, built the largest amateur telescope ever with a whopping 70 inch primary mirror he purchased at auction. The entire telescope is 35 feet tall, 900 pounds, and he hopes to tour it in parks. As a hand-turned Dobsonian the telescope lacks the photographic capacity and tracking required for professional astronomy but the views must be breathtaking." (Are there other compelling candidates out there for "largest amateur telescope ever"? The 71" scope listed by nitesky.org appears to be dormant.)
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Cold War Spoils: Amateur Builds Telescope With 70-Inch Lens

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  • by DaTrueDave (992134) * on Tuesday November 05, 2013 @02:34PM (#45337779)

    This is unclear to me:

    "One of the riskiest parts of the project was turning the huge 70-inch piece of glass into a mirror by applying the silvering himself."

    vs.

    "Clements bought the 900-pound mirror — which was originally destined to go into space as part of a spy satellite until the edge of it was chipped during its manufacture — after it was auctioned off."

    • by Anonymous Coward on Tuesday November 05, 2013 @02:40PM (#45337873)

      He put a reflective metal coating on a purchased piece of glass with the proper final curvature.

    • by pla (258480) on Tuesday November 05, 2013 @02:44PM (#45337925) Journal
      I took that to mean they just cancelled the satellite project after casting and polishing the mirror but before silvering it.

      Alternatively, the intended use may have involved some classified exotic coating that serves some special purpose and they needed to strip the coating before selling the mirror at auction.
      • by Frobnicator (565869) on Tuesday November 05, 2013 @03:02PM (#45338137) Journal

        I read it the same way.

        They probably cut the mirror and polished the glass, and then the edge chipped.

        A chip in the glass could be a fatal injury for a spy satellite as the article suggests was the intended use. Such telescopes use active optics to improve image quality; they apply pressure over the glass to bend it slightly. A chip could have micro-cracks and other damage that would easily spread across the surface. Without the actuators deforming the glass the image won't be as clear, but it would be good enough for a hobby telescope.

        Once the glass chipped they likely just stopped the process, so the new owner would need to add the mirror surface on his own.

        • by Anonymous Coward

          They talk about it over on cloudynights,
          The crack goes about a foot into the glass. The spray on coating leaves much to be desired, it needs to be re-coated every so often and it has a fairly low reflection index for whats commonly used in telescope mirrors. But with that said its still a hell of a project and I'd love to use it!

        • by wagnerrp (1305589) on Tuesday November 05, 2013 @05:49PM (#45340015)

          A chip in the glass could be a fatal injury for a spy satellite as the article suggests was the intended use. Such telescopes use active optics to improve image quality;

          Why? It's in microgravity and temperature controlled. There's not going to be any sort of variation during operation to make active optics worthwhile. It's certainly not going to be adaptive optics, because you're moving across the atmosphere too rapidly to have any hope of keeping up with localized distortions. The only reason I could see it being useful is it would allow for more lax manufacturing tolerances, since you could fine tune it once you hit orbit.

          • by HuguesT (84078)

            State of the art spy satellite require active optics because they look at things through the atmosphere. Not upward like a ground-based astronomy telescope, but downwards.

            • The atmosphere has nothing to do with anything. Active optics exist to maintain the shape of a mirror to compensate for changing external stresses. Unless you're inside the atmosphere, the atmosphere cannot produce external stress on the mirror. Of course, if you are inside the atmosphere, you have bigger issues than worrying about good quality images.
          • by Deadstick (535032) on Tuesday November 05, 2013 @08:29PM (#45341313)

            Why? It's in microgravity and temperature controlled.

            When you're in orbit, "temperature controlled" is a slippery concept. You've got direct sunlight on one side, dark space on the other side, temperatures to the fourth power fighting it out, and no air to redistribute heat -- and an hour later, the sides will have switched.

        • So what kind of detail can one see on the moon; maybe the Hollywood sets of the moon landings?
        • A chip in the glass could be a fatal injury for a spy satellite as the article suggests was the intended use. Such telescopes use active optics to improve image quality; they apply pressure over the glass to bend it slightly. A chip could have micro-cracks and other damage that would easily spread across the surface. Without the actuators deforming the glass the image won't be as clear, but it would be good enough for a hobby telescope.

          Once the glass chipped they likely just stopped the process, so the new owner would need to add the mirror surface on his own.

          Not so. Firstly, adaptive optics is still fairly rare and likely this mirror was never intended for use in such a telescope. Secondly, the mirror deformations on a telescope with adaptive optics are not done at the primary mirror (the large chipped one) but at the secondary or even tertiary mirror. It's much easier to do this on a small, thin, mirror than large, thick one. Finally, a little chip is no big deal. You just coat the mirror as normal then paint over the chipped area. You'll never see the differ

          • I don't know this for a fact but I am dubious that adaptive optics can or are used for telescopes looking down at earth. From my lay understand of adaptive optics, a "guide star" or artificial star (artificial spot in the sky lit up with a frickin laser!) is used to correct for the atmospheric disturbances. I am having a hard time thinking of what could be used as a point source when looking at the ground from space. Maybe a point light source near the area of interest?

            • by Anonymous Coward

              I'm a scientist working in adaptive optics. Reading this whole thread, in which essentially every statement made is untrue or imprecise, gives me some idea of what it must be like to be a climate scientist listening to constant babble from people trying to talk about a technical area outside their area of expertise. (No insult intended toward any commenters in this thread, I'm just sharing my epiphany.)

            • by drinkypoo (153816)

              I am having a hard time thinking of what could be used as a point source when looking at the ground from space. Maybe a point light source near the area of interest?

              So just to be clear, you're having such a hard time figuring it out, that you just figured it out?

            • by cellocgw (617879)

              No, the main reason that AO is not used for atmospheric correction in satellite systems is the so-called "shower curtain" effect. The atmospheric aberration effect is strong for ground telescopes because the atmosphere is near the 'scope, and thus is in the region where the light's phase is important. Looking down from a satellite (analogous to looking from the far side of the room at a person just behind a shower curtain), the atmosphere is where the light's angle is important, not phase.

    • by Hadlock (143607)

      If you stick a 900 lb piece of glass on top of a rumbling shaking rocket and expose it to 5Gs of acceleration, rapid heating and cooling cycles etc, you probably don't want a chip in the glass where forces can propagate a crack. It's easier to make a new one rather than wait for it to fail in space.

      For something that will only see occasional use with slow temperature changes it's ideal for a "low cost" telescope. It will still fail eventually, but it won't shatter in orbit while imaging a North Kore

      • by kimvette (919543)

        > it will still fail eventually

        Not necessarily, if he took the time to de-stress the chip. It will still be a weak point but will not necessarily propagate.

  • by Arkh89 (2870391) on Tuesday November 05, 2013 @02:48PM (#45337969)

    According to TFA : enabling users to see constellations previously visible only through the $2.5 billion Hubble Space Telescope
    Hahaha, but no...

    • by Virtucon (127420) on Tuesday November 05, 2013 @02:59PM (#45338109)

      Riiight.. I mean the guy lives in Utah so there are dark skies close enough to him but I'm plagued with air pollution and light pollution in my area and have to go at least 3 hours away to get a decent night of observation. Even then you still have upper atmospheric interference at times whereas the HST doesn't have any of that. The other problem I'd see with a Dobsonian of this size is maneuvering it and hauling it without damaging it. Props too him though for building it though, I wonder how many times he had to go to Home Depot to finish it?

      • by gandhi_2 (1108023)

        Actually, west jordan is in the massive sprawl complex that stretches from North Ogden to Nephi. He would probably have at least a couple hours drive to get up past Park City, Heber, Payson, or out towards the west desert, Tooele, or even Dugway He will have some driving if he wants darkness. Utah'ns in general take a "consumptive model" view of nature, and aren't big into reducing pollution, let alone LIGHT pollution.

      • Also, I think any of the scopes on Mauna Kea or the Andes would blow this thing out of the water.
        Cool project, though.
    • It's an impressive amateur engineering feat, but its performance as a telescope might not be anything to write home about. It probably shares one quality with the hubble that you wouldn't want: a problem with gravity.

      Remember how when it first went up, the hubble had problems focusing clearly? The designers forgot that its mirrors would be deformed/reshaped by the lack of gravity. Essentially, the hubble's primary mirror was optically designed to work as a telescope mirror on earth, not in space. It w
      • by the_other_chewey (1119125) on Wednesday November 06, 2013 @02:08AM (#45342833)

        Remember how when it first went up, the hubble had problems focusing clearly? The designers forgot that its mirrors would be deformed/reshaped by the lack of gravity. Essentially, the hubble's primary mirror was optically designed to work as a telescope mirror on earth, not in space.

        Uh, no. That would've been an amateur mistake to make and didn't happen.
        Instead, the amateur mistake made was not to properly verify that the grinding
        machine was actually grinding correctly. They even ignored measurments by
        another instrument showing a faulty shape, assuming the instrument to be faulty instead.
        And skipped the final post-assembly check to save time and money.

        The mirror simply was ground extremely precisely into a wrong shape, and nobody noticed.

        But as always in cases like this, the whole story is more complex and consists of a lot of
        things not going as planned. It's a good and instructive read. [tamu.edu]

        • by hubie (108345)
          The beauty, of course, is because it was so precisely ground into a wonderfully specific shape (it gave perfect spherical aberration), it was easy to make corrective lenses.
  • by Joining Yet Again (2992179) on Tuesday November 05, 2013 @02:48PM (#45337973)

    Just a heads up for you non-Brits. There will be truth in this article... somewhere.

  • by Anonymous Coward on Tuesday November 05, 2013 @02:49PM (#45337997)

    Technically Lord Rosse (https://en.wikipedia.org/wiki/William_Parsons,_3rd_Earl_of_Rosse) was an amateur, and his telescope was 72 inches.

    • by Servaas (1050156)

      I think once you carry the Lord title you can never again be revered to as an amateur in anything.

      • It's not as impressive as it sounds. The title is heretitary, so it basically means 'My ancestors were filthy stinking rich, and I probably am too.'

        When we want to grant someone a title of respect, they get the 'Sir' before their name, not Lord. You have to earn that one personally, not just get born into it.

        • by gandhi_2 (1108023)

          This guy earned "Long Haul Trucker" and is building a telescope with money he works for.

          I find that much more respectable than the right honorable lord sir fuckface pursuing hobbies with leisure time and leisure money.

      • by forkazoo (138186)

        To the contrary, you can never be referred to as a professional. Having to work a job is for the little non Lord people.

    • by careysub (976506)

      Lord Rosse's telescope used a cast speculum metal mirror [wikipedia.org], basically pewter, which had a reflectivity of 66%. Glass silvering technology had not been developed to a level adequate for astronomical mirrors. As a result the light gathering power of the 72" Leviathan of Parsontown was equivalent to a 58" mirror of 100% reflectivity. Clement's mirror is coated with silver, and with even a mediocre silvering job a reflectivity at least 90% should be obtained. This makes his mirror equivalent to a 66" mirror of 10

      • by martinux (1742570)

        William Parsons (Lord Rosse) cast and figured his mirrors with 1845 technology that he helped improve through his own efforts. It doesn't matter what the sensitivity or apparent size is in relation to a mirror created with 20th century technology developed by Lockheed with unknown millions in government funding. The Leviathan has a larger diameter mirror which is the criteria many news sources are using to claim that Mr. Clements's telescope is the largest ever built.

        I'm saddened to see that this has turned

        • by martinux (1742570)

          Correction: Obviously 1845 was not over 200 years ago. I don't think this undermines the point, however.

  • You really don't need a mirror this large to spy on your neighbor.

    Or so I've heard.
    • No, but oriented in the proper way, you can start fires at random locations all over their property, causing them to believe that they have poltergeists.
    • You really don't need a mirror this large to spy on your neighbor.

      It depends on how large the neighbor is...

  • How hard is it to rig up a camera adapter? That'd help demonstrate exactly how powerful it is...
    • I was wondering the same thing. Thought it might be a stability issue since the rig has no gears and it's moved by hand?

      • Even with tracking capability, which isn't that hard for a dobsonion, alta-azimuth mounts like this suffer from field rotation effects and exposures longer than about 30 seconds are not ideal. But you can take many 30 second exposures and stack them to give you something resembling a much longer exposure. The stacking de-rotates the images and aligns them.
        • Or you can build a rotating camera mount, or insert a rotating element in the optical path. Either way, you're supporting and moving a relatively small weight, so it's a much easier task than building the main drive.

          • Yep field de-rotators are an option. Sometimes the right option, but they are an added drive system and can be pesky. I would say in this case a much better option than trying to build an equatorial mount for an instrument this large.
        • by careysub (976506) on Tuesday November 05, 2013 @05:15PM (#45339667)

          Taking short exposures and processing them on a computer is the "poor man's adaptive optics". A very powerful technique (if the object is bright enough) is too take a large number (thousands) of short exposures, then sort through them for a "lucky" image - one in which the atmosphere is momentarily stable. Multiple lucky images can be stacked together to get longer exposures. This really is a very powerful technique, not requiring extremely expensive high precision tracking hardware.

    • by necro81 (917438)
      Well, you see, the reporters from the Daily Mail came and did the interview and photographs during the daytime. They may have glossed over that part that astronomical telescopes are typically used at night.
  • by crunchygranola (1954152) on Tuesday November 05, 2013 @03:03PM (#45338143)

    Here is the scoop on the 70" telescope. Mike Clements purchased a polished but uncoated mirror that is 70" across that was intended for a spy satellite project that was cancelled. A huge uncoated mirror is not a telescope anymore than (car analogy - wait for it...) a V8 engine is a racecar. Building a good performing telescope (collimation tolerances are measured in thousandths of an inch) is a significant task, a huge telescope like this is a major engineering feat. What's more this is a transportable telescope. It is possibly the biggest transportable telescope in the world. This telescope is more powerful than any telescope that existed before 1917 (when the 100" Hooker telescope saw first light).

    Successfully silvering the mirror using updated 19th Cedntury mirror coating technology was nifty too.

  • I have a Dobsonian 22" Mirror that I built from scratch about 10 years ago.

    A telescope is only as good as it's lenses. Normal lenses I call Coyote Lenses because they are so crappy that they are only good for throwing at coyotes during star parties.

  • Some further info... (Score:5, Informative)

    by Zarquon (1778) on Tuesday November 05, 2013 @03:16PM (#45338229)

    Cloudy nights thread [cloudynights.com] and a another news article [ksl.com].

    It was silvered with a spray-on solution using a weed sprayer; much too large for the regular vacuum deposition chambers.

    -R C

  • by Bearhouse (1034238) on Tuesday November 05, 2013 @03:53PM (#45338679)

    Truely "news for Nerds". Brings back fond memories of building 'scope and staring at the skies with my father.
    This man has drive, dedication and the ability to both conceptualise and physically realise his dreams.

    Instead of bullshit "surveys" with no-longer-funny "CoboyNeal" options, here's a serious suggestion - how about we instigate the /. annual "Nerd" awards?

    Fuck it, this is going way offtopic, but I don't care...categories anyone?

    • Most nostalgic old guy crapping on new stuff in a Slashdot post.

    • by Inda (580031)
      Yep, more of these please.

      I know nothing of Astrology* and telescopes, but these stories spark imagination.

      *I know what word I typed.
  • by Flere Imsaho (786612) on Tuesday November 05, 2013 @04:31PM (#45339119)

    You don't really appreciate what an awesome amateur effort this is until you see pics http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/6146228/page/0/view/collapsed/sb/5/o/all/fpart/2/vc/1 [cloudynights.com]

    Being the owner of an 8" Schmidt–Cassegrain scope, this blows my mind.

  • Right after submitting this I noticed my goof in the title. As a refracting telescope the primary optical device is a mirror, not a lens. Slapping myself in the face.
  • he didnt bother to post any pictures captured with it. Only pictures of an ugly metal contraption.

    • by Noofus (114264) *

      Dobsonian-style telescopes are generally not capable of proper astrophotography. Withouth significant work to put this thing on a barn-door-style tracking motor drive, as well as a setup that rotates the camera in the "eyepiece" holder to account for field rotation, this wont work well to capture images.

  • My big lens story (Score:4, Interesting)

    by mknewman (557587) on Tuesday November 05, 2013 @05:39PM (#45339919)
    Years and years ago, around 1976, I had a tube type TV that went fritz so I took it to an Austin, Tx TV repair shop. The guy took it in the back to work on and while he was doing it I looked around his shop and there were quite a few very nice amateur astronomy photos, Jupiter, Saturn, the Moon and such. I was taking some astronomy classes at UT. When he came out we got talking and he told me he was into astronomy. Now, this shop was a WRECK, much like most TV repair shops I have ever seen. pretty much a dump. He asked me to come in the back to 'See something'. The guy was about 6'6" tall and BIG, and rough looking, and I am NOT, so I declined, but he insisted so I finally went through a maze of old junk, narrow dark halls, and finally got to the back of the store. I was kinda scared. He pointed to something on the ground. It was a round plug of glass on a large wooden palate. My jaw dropped, I asked him if it was what I thought and he confirmed it was a slug for a 6 ft telescope. I believe he said he got it at auction when a Swiss observatory had two made and the first worked out, so he got it cheap. It was unfinished, just a blob of glass, but at the time I'd only seen telescopes in the 36" range and this was huge! He was grinning ear to ear, and I was astounded. I believe his name was Chuck Knesek but I may be wrong or only close. It's been 35+ years. I never saw him again. If anyone knows what happened to him or his slug I'd love to know.

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