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Cold War Spoils: Amateur Builds Telescope With 70-Inch Lens
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.)
He put a reflective metal coating on a purchased piece of glass with the proper final curvature.
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.
Just a heads up for you non-Brits. There will be truth in this article... somewhere.
Technically Lord Rosse (https://en.wikipedia.org/wiki/William_Parsons,_3rd_Earl_of_Rosse) was an amateur, and his telescope was 72 inches.
How hard is it to rig up a camera adapter? That'd help demonstrate exactly how powerful it is...
PHEM - party like it's 1997-2003!
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?
Harrison's Postulate - "For every action there is an equal and opposite criticism"
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.
//TODO: Think of witty sig statement
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.
Second class citizen of the New Gilded Age
Cloudy nights thread and a another news article.
It was silvered with a spray-on solution using a weed sprayer; much too large for the regular vacuum deposition chambers.
-R C
"'Tis great confidence in a friend to tell him your faults, greater to tell him his." --Poor Richard's Almanac
Reflecting telescopes use front-side mirrors. The glass is just there to provide the shape; it is not part of the optical path.
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?
"Charlize Theron NSFW"
I keep clicking on those words, but nothing happens :(
You might owe yourself another slap. It's a reflecting telescope. Grins.
Trying to become famous by taking photos. Visit my homepage please.
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.
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.
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.
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.