Engineering Marvel
March 5, 2021 8:49 PM Subscribe
The biggest mirror telescope ever has come closer to completion! Phys.org tells us Sixth mirror cast for Giant Magellan Telescope. The casting process will take 2.5 months before it reaches room temperature, and then begins 4 years of polishing. The lab where this is happening is under the UArizona football stadium. Here's a video from UArizona's Mirror Lab talking about the process, with footage of the process. [2m52s]
I remember when mirror 5 was cast a few years back, and was wondering what was going on with this project that I couldn't remember the name of. I was happy to see this update today and go "oh, yeah!" Also went "science is groovy!"
I remember when mirror 5 was cast a few years back, and was wondering what was going on with this project that I couldn't remember the name of. I was happy to see this update today and go "oh, yeah!" Also went "science is groovy!"
Fascinating stuff.
When I was a kid this was my favorite exhibit at the Corning Glass Museum. Still pretty awe-inspiring.
posted by kinnakeet at 5:55 AM on March 6, 2021 [2 favorites]
When I was a kid this was my favorite exhibit at the Corning Glass Museum. Still pretty awe-inspiring.
posted by kinnakeet at 5:55 AM on March 6, 2021 [2 favorites]
(In case you were wondering: previously and with some more background on the project and some cool videos, though I see one of these links is now dead.)
posted by Insert Clever Name Here at 8:07 AM on March 6, 2021
posted by Insert Clever Name Here at 8:07 AM on March 6, 2021
Did not know that borosilicate glass was dangerous. Interesting.
posted by Splunge at 8:19 AM on March 6, 2021
posted by Splunge at 8:19 AM on March 6, 2021
This video copy is still viewable. It's probably the same as one of the dead links from the "previously": Making the mirrors for the Giant Magellan Telescope. It's interesting to see the different methods from the Hale mirror in the Corning video above.
This video is all the steps from building the mold, melting, and removing the back ceramic. Not the polishing.
~~~~
The future Extremely Large Telescope is a different design. It's smaller segments are supported by active suspensions to control the mirror shape.
From the link:
...the 39-metre-diameter mirror will consist of 798 segments, each about 5 centimetres thick, measuring close to 1.5 metres across and weighing 250 kg, including its support. Since the segments have to work together as a single mirror, they require specific infrastructure and control schemes. This is extremely challenging, as the full structure will be moving constantly during an observation and will be affected by wind and thermal changes. To achieve the required scientific performance, the mirror needs to be maintained in position and in shape to an accuracy of tens of nanometres — 10000 times thinner than a human hair — across its entire 39-metre diameter!
posted by jjj606 at 8:26 AM on March 6, 2021 [6 favorites]
This video is all the steps from building the mold, melting, and removing the back ceramic. Not the polishing.
~~~~
The future Extremely Large Telescope is a different design. It's smaller segments are supported by active suspensions to control the mirror shape.
From the link:
...the 39-metre-diameter mirror will consist of 798 segments, each about 5 centimetres thick, measuring close to 1.5 metres across and weighing 250 kg, including its support. Since the segments have to work together as a single mirror, they require specific infrastructure and control schemes. This is extremely challenging, as the full structure will be moving constantly during an observation and will be affected by wind and thermal changes. To achieve the required scientific performance, the mirror needs to be maintained in position and in shape to an accuracy of tens of nanometres — 10000 times thinner than a human hair — across its entire 39-metre diameter!
posted by jjj606 at 8:26 AM on March 6, 2021 [6 favorites]
The process is much more manual than I'd imagine; placing glass from a rotating gantry...
posted by monocultured at 8:34 AM on March 6, 2021
posted by monocultured at 8:34 AM on March 6, 2021
This video copy is still viewable.
Ah! Yes, that was the one I recall from the previously (which now has a dead link). Thanks!
posted by Insert Clever Name Here at 8:35 AM on March 6, 2021
Ah! Yes, that was the one I recall from the previously (which now has a dead link). Thanks!
posted by Insert Clever Name Here at 8:35 AM on March 6, 2021
The portion of the video showing the hunks of glass liquefying is just beautiful. Does it first get turned into an essentially-flat plane, then polished into its curved form?
posted by migurski at 6:59 PM on March 6, 2021 [1 favorite]
posted by migurski at 6:59 PM on March 6, 2021 [1 favorite]
The spinning mold produces a parabolic surface due to the centrifugal forces. So they spin it to get a head start on the grinding.
posted by TheJoven at 7:16 PM on March 6, 2021 [2 favorites]
posted by TheJoven at 7:16 PM on March 6, 2021 [2 favorites]
Tuscon has a lot of cool astronomy options.
posted by gottabefunky at 7:45 PM on March 6, 2021 [1 favorite]
posted by gottabefunky at 7:45 PM on March 6, 2021 [1 favorite]
The spinning mold produces a parabolic surface due to the centrifugal forces. So they spin it to get a head start on the grinding.
It was amazing when the oven started spinning like The Neville Bros doing a show in a Theater in the Round.
posted by mikelieman at 4:25 AM on March 7, 2021
It was amazing when the oven started spinning like The Neville Bros doing a show in a Theater in the Round.
posted by mikelieman at 4:25 AM on March 7, 2021
OK, so this is really cool. I was able to tour the mirror lab a few years ago while they were making another one of the mirrors (and my season tickets for U of A football are close to the mirror lab, which is right up against the stadium but isn’t connected at all, as you wouldn’t want a noisy stadium causing unwanted vibrations in the lab during casting and polishing work.
But you wanna know something else really cool? Those mirrors can’t be taken apart for transport. They have to be hauled in one piece. That is no easy trick. The Large Binocular Telescope on Mt. Graham has similar sized mirrors, and these mirrors had to be hauled up a winding, steep. Mountain road. (I have been up this mountain several times and it’s absolutely amazing they were able to pull this off. That is the only road where I have ever gotten motion sickness. It’s crazy.) About 3000 man-hours went into the operation. Here’s a link with the description of how they had to prepare and haul the mirror, with pics at the end of the article. Hauling a giant mirror up a steep mountain
posted by azpenguin at 9:19 PM on March 7, 2021 [1 favorite]
But you wanna know something else really cool? Those mirrors can’t be taken apart for transport. They have to be hauled in one piece. That is no easy trick. The Large Binocular Telescope on Mt. Graham has similar sized mirrors, and these mirrors had to be hauled up a winding, steep. Mountain road. (I have been up this mountain several times and it’s absolutely amazing they were able to pull this off. That is the only road where I have ever gotten motion sickness. It’s crazy.) About 3000 man-hours went into the operation. Here’s a link with the description of how they had to prepare and haul the mirror, with pics at the end of the article. Hauling a giant mirror up a steep mountain
posted by azpenguin at 9:19 PM on March 7, 2021 [1 favorite]
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