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Thread: Very Big Telescopes

  1. #1 Very Big Telescopes 
    Forum Professor arKane's Avatar
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    Of the telescopes listed below most should come online before 2020. I get excited just thinking about it. When you think about what's been discovered with current generation telescopes in the 10 m range, these behemoths should be able to resolve some of the big questions of our universe and spy on the aliens playing in there backyards.

    I'm just wondering if others on this forum share my excitement about these super scopes?


    THE EUROPEAN EXTREMELY LARGE TELESCOPE ("E-ELT") PROJECT (42 m)
    http://www.eso.org/sci/facilities/eelt/

    Overwhelmingly Large Telescope (OWL) (100 m)
    http://www.eso.org/sci/facilities/eelt/owl/

    MAXAT - the Maximum Aperture Telescope (30-50 m)
    http://www.gemini.edu/science/maxat/

    Thirty Meter Telescope Project (TMT)
    http://www.tmt.org/

    The LAMA* telescope employs an array of fixed 10-meter liquid-mirror telescopes. These are located in a closely-packed configuration with an overall diameter of 54 meters. Approximately 62% of the light that falls within this area is collected and focused on a common detector. This gives the array a light-collecting power equivalent to that of a 42 m telescope.
    http://www.astro.ubc.ca/LMT/lama/index.html

    Cerro Chajnantor Atacama Telescope (CCAT) (25 m)
    A giant sub-millimeter telescope that will be erected in the Chilean desert in order to help unravel the cosmic origins of stars, planets, and galaxies.
    http://submm.org/ccat.html

    The Very Large Telescope (VLT) is made up of four separate optical telescopes (the Antu telescope, the Kueyen telescope, the Melipal telescope, and the Yepun telescope) organized in an array formation, built and operated by the European Southern Observatory (ESO) at the Paranal Observatory on Cerro Paranal, a 2,635 m high mountain in the Atacama Desert in northern Chile. Each telescope has an 8.2 m aperture. The array is complemented by four movable Auxiliary Telescopes (ATs) of 1.8 m aperture. Working together in interferometric mode, the telescopes can achieve an angular resolution of around 1 milliarcsecond, meaning it could distinguish the gap between the headlights of a car located on the moon.
    http://eso.org/public/teles-instr/vlt.html

    The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope, scheduled for launch in 2014. Webb will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. Webb will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. Webb's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.
    Webb will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Both the mirror and sunshade won't fit onto the rocket fully open, so both will fold up and open once Webb is in outer space. Webb will reside in an orbit about 1.5 million km (1 million miles) from the Earth.
    http://www.jwst.nasa.gov/


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    I like these projects except for the James Webb Space Telescope.

    What I don't like about the James Webb Space Telescope are the huge cost overruns and high risk of failure. It will be orbiting at L2, which will be out of range for maintenance or repars for decades. It's too risky and too expensive. Given NASA's fragile public image and the grass roots movement to cut the government, a mishap could mean the end of entire program as we know it.


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    Quote Originally Posted by Lynx_Fox
    I like these projects except for the James Webb Space Telescope.

    What I don't like about the James Webb Space Telescope are the huge cost overruns and high risk of failure. It will be orbiting at L2, which will be out of range for maintenance or repars for decades. It's too risky and too expensive. Given NASA's fragile public image and the grass roots movement to cut the government, a mishap could mean the end of entire program as we know it.
    I can't say I don't have sympathy with your feelings about the James Webb Space Telescope. But if you recall the Hubble Telescope suffered pretty much the same criticisms and cost over runs. But once they finely got it up and working as promised it was spectacular and nobody was sorry to have spent the money.

    Part of the problem is NASA's bidding process. They are chronic under bidders of cost, because they fear they will not be funded if they gave a realistic bid on the project. It's much easier to get started then ask for more money once the hook has been set. After all if you've already spent 5 billion what's another billion and a half as compared with scrapping the project altogether?

    I think NASA should be made to handle much of their funding in a similar manner to the way all these other telescope projects do for their funding. I would be willing to bet there are ways they could do at least half their funding through private means.

    Having said that I am still very much looking forward to the success of the mission.
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    Quote Originally Posted by Lance Wenban
    I can't say I don't have sympathy with your feelings about the James Webb Space Telescope. But if you recall the Hubble Telescope suffered pretty much the same criticisms and cost over runs. But once they finely got it up and working as promised it was spectacular and nobody was sorry to have spent the money.
    Hubble is a good example that NASA should have learned from. First off there were some early problems, particularly the bad lens which needed to be repaired. These machines are so complex that problems are almost likely. Unfortunately the James Webb space Telescope will be out of reach for any sort of hardware repairs--a really bad design decision. It would have made a lot more sense to wait a decade or so until we had a vehicle which could reach it after deployed.

    Another lesson they should have learned is not everything NASA does is about the science. Hubble reached the point of deminishing scientific returns many years ago which is why they tried to shut it down. But they continue to fail to understand that those fantastic pictures, whether they were of scientific interest, generated enormous popularity and interest from tax payers who pay their bills (indirectly). If you want support for large programs than you've got to get past the sterile objective science and make it "sexy," and understandable. (Heck I think this point goes towards all sciences in general).

    Part of the problem is NASA's bidding process.
    I don't know much about their particular bidding process but I have been around government most of my life and imagine how things work. It's hard to manage when a few skill sets are so vital to your program that it makes it difficult to make the hard choices and cut contractors off when they don't produce--yet that's what probably needs to happen to fix the culture.

    Having said that I am still very much looking forward to the success of the mission.
    I am too. (crosses fingers)
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  6. #5  
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    Quote Originally Posted by Lynx_Fox
    Hubble is a good example that NASA should have learned from. First off there were some early problems, particularly the bad lens which needed to be repaired. These machines are so complex that problems are almost likely. Unfortunately the James Webb space Telescope will be out of reach for any sort of hardware repairs--a really bad design decision. It would have made a lot more sense to wait a decade or so until we had a vehicle which could reach it after deployed.

    Another lesson they should have learned is not everything NASA does is about the science. Hubble reached the point of deminishing scientific returns many years ago which is why they tried to shut it down. But they continue to fail to understand that those fantastic pictures, whether they were of scientific interest, generated enormous popularity and interest from tax payers who pay their bills (indirectly). If you want support for large programs than you've got to get past the sterile objective science and make it "sexy," and understandable. (Heck I think this point goes towards all sciences in general).

    Part of the problem is NASA's bidding process.
    I don't know much about their particular bidding process but I have been around government most of my life and imagine how things work. It's hard to manage when a few skill sets are so vital to your program that it makes it difficult to make the hard choices and cut contractors off when they don't produce--yet that's what probably needs to happen to fix the culture.

    Having said that I am still very much looking forward to the success of the mission.
    I am too. (crosses fingers)
    You make a very strong point about waiting another decade, but as it is, the (JWST) will be lucky to launch by 2015 and that's half a decade. Then you also have to remember the return to the moon and Mars missions will be taking center stage after 2020. Next I have to believe they've taken into account where they plan to park the (JWST), one can only hope they know what they are doing. At least it's going to be outside the orbit of most of the junk floating around Earth and we will need capable space craft if we are going to start dealing with asteroid threats.

    I think if anything the government will have to step up their funding in many areas of off world activities, due to the Chinese and several other countries that are upping the ante in their own space programs. I'd be very surprised if we don't start having trouble holding the high ground over the next couple of decades.

    Also as far as the (JWST) goes, I'd like to see some results before I cash in my chips. I am hoping for another 20 years, but you never know.
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    I agree with some of the earlier statements. However, it is a GOOD design to place it at L2, just like previous missions like WMAP, Herschel and Planck. All these probes were and are very successful. Certainly, putting the telescope at such a distance requires the conceptional design as well as the pre-launch test campaign to be very robust and fool proof. In particular the idea of the unfolding main mirror and the flipping secondary mirror support gives me the chills. From internal discussions, I hear that the costs for the JWST is up at about 8 billion $ right now, and the launch is delayed at least until end 2015. Most experts expect a realistic launch window some time in 2017.
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    Quote Originally Posted by Dishmaster
    I agree with some of the earlier statements. However, it is a GOOD design to place it at L2, just like previous missions like WMAP, Herschel and Planck. All these probes were and are very successful. Certainly, putting the telescope at such a distance requires the conceptional design as well as the pre-launch test campaign to be very robust and fool proof. In particular the idea of the unfolding main mirror and the flipping secondary mirror support gives me the chills. From internal discussions, I hear that the costs for the JWST is up at about 8 billion $ right now, and the launch is delayed at least until end 2015. Most experts expect a realistic launch window some time in 2017.
    Did you say 8 billion now? That's quite a price tag for one instrument being placed in a difficult position to support. All I can say is success in this endeavor will be very impressive indeed. I'd prefer not thinking about what a failure will make us look like or how it would affect future support for big ticket projects. Having said that I'm glad we will be getting some high powered competition from the Chinese. There's nothing like the thought of being left behind to keep up a good level of motivation.
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    I'm so pleased with the mercury mirror zenith telescopes. Few things so embody genius.

    I have an idea, to build bigger ones. Currently, our dish is mounted on crazy-expensive bearings, to dampen vibrations from the motor. Of course the heavier the dish, the greater the expensive bearings.. 'till you just can't find machine shops capable of building them or you can't find the money. I propose "mounting" the dish in a slightly larger *dish* of water. The water would circulate around. Both dishes could be concrete, built the same way we build swimming pools and stadiums, on a similar scale.

    I guess in this idea are glaring problems I don't see.
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    Quote Originally Posted by Pong
    I'm so pleased with the mercury mirror zenith telescopes. Few things so embody genius.

    I have an idea, to build bigger ones. Currently, our dish is mounted on crazy-expensive bearings, to dampen vibrations from the motor. Of course the heavier the dish, the greater the expensive bearings.. 'till you just can't find machine shops capable of building them or you can't find the money. I propose "mounting" the dish in a slightly larger *dish* of water. The water would circulate around. Both dishes could be concrete, built the same way we build swimming pools and stadiums, on a similar scale.

    I guess in this idea are glaring problems I don't see.
    I find everything about big telescopes completely fascinating, but unfortunately I have no expertise in their construction and can't offer any advice about your idea or any possible glaring problems. But it looks like you might be trying to use water as a reflector. If that's true, can you elaborate a bit on how that might work. I do like naval ideas and original thinking.
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    The reflector would be mercury, like normal. That would spread in a spinning dish, like normal. The difference is that my dish would not be mounted on huge yet tightly enginered bearings, rather the dish would sit in another dish (of water), as a bearing.

    Obviously a concrete dish is very well supported in a pool of water, so there is no problem with the thing deforming under its own weight, or wobbling, etc.

    Gently circulating water can spin the dish, and center it. You won't get any motor vibrations.
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  12. #11  
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    Quote Originally Posted by Pong
    The reflector would be mercury, like normal. That would spread in a spinning dish, like normal. The difference is that my dish would not be mounted on huge yet tightly enginered bearings, rather the dish would sit in another dish (of water), as a bearing.

    Obviously a concrete dish is very well supported in a pool of water, so there is no problem with the thing deforming under its own weight, or wobbling, etc.

    Gently circulating water can spin the dish, and center it. You won't get any motor vibrations.
    That does sound very interesting, can you tell me how you might hold it on a fixed viewing position as the earth rotates? Also how would you be able to apply adaptive optics to this device?
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    Quote Originally Posted by Pong
    I have an idea, to build bigger ones. Currently, our dish is mounted on crazy-expensive bearings, to dampen vibrations from the motor. Of course the heavier the dish, the greater the expensive bearings.. 'till you just can't find machine shops capable of building them or you can't find the money. I propose "mounting" the dish in a slightly larger *dish* of water. The water would circulate around. Both dishes could be concrete, built the same way we build swimming pools and stadiums, on a similar scale.

    I guess in this idea are glaring problems I don't see.
    Since I read your post and what you said about bearings reaching their size limitations based on engineering and cost. I started thinking of other possible bearing types that might solve the problem and I remember seeing a program on TV about some guy that builds small wind generators that can be fitted on rooftops of houses and buildings, and this wind generator used magnetic bearings. They were completely silent and near frictionless in use. Then I started thinking of meglev trains and realized these magnetic fields can support very large structures. But like you I often miss glaring problems.
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    Quote Originally Posted by Lance Wenban
    can you tell me how you might hold it on a fixed viewing position as the earth rotates? Also how would you be able to apply adaptive optics to this device?
    Zenith telescopes point straight up. Moreover, with a liquid mirror type any move to aim the dish ripples its surface. So, you get to see just what your installation happens to be pointing at. *But* you get fantastically deep images, at low cost.

    The latest generation of these telescopes pads the bearings with compressed air.

    Seems to me the more elegant way to support a dish, level, is in water. Especially for dishes a few hundred meters diameter. Water costs practically nothing to supply and maintain.
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    Quote Originally Posted by Pong
    Zenith telescopes point straight up. Moreover, with a liquid mirror type any move to aim the dish ripples its surface. So, you get to see just what your installation happens to be pointing at. *But* you get fantastically deep images, at low cost.
    I'd be very interested in seeing some pictures from one of these Zenith telescopes. Can you post a web site I can visit to view these pictures?

    Also, I was always under the impression that to get fantastically deep images required a long exposure time which would be impossible with a Zenith telescope. Can you explain why the Zenith system works so well?
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    Let's await the aptly named Dishmaster.
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    Quote Originally Posted by Pong
    Let's await the aptly named Dishmaster.
    Maybe this can help to save my reputation:
    http://www.astro.ubc.ca/lmt/
    http://science.nasa.gov/science-news..._liquidmirror/
    http://www.aeos.ulg.ac.be/LMT/
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  18. #17  
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    Quote Originally Posted by Dishmaster
    Quote Originally Posted by Pong
    Let's await the aptly named Dishmaster.
    Maybe this can help to save my reputation:
    http://www.astro.ubc.ca/lmt/
    http://science.nasa.gov/science-news..._liquidmirror/
    http://www.aeos.ulg.ac.be/LMT/
    Your reputation is safe. The information at those sites was just what I needed to understand the liquid mirror concept.

    I especially liked the concept of putting a large one on the moon. I did notice they talked about using a superconducting bearing for the moon system. I can see the advantage of that given the environment it would be operating in.
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    [quote="Lynx_Fox"]
    Quote Originally Posted by Lance Wenban
    IAnother lesson they should have learned is not everything NASA does is about the science. Hubble reached the point of deminishing scientific returns many years ago which is why they tried to shut it down. But they continue to fail to understand that those fantastic pictures, whether they were of scientific interest, generated enormous popularity and interest from tax payers who pay their bills (indirectly). If you want support for large programs than you've got to get past the sterile objective science and make it "sexy," and understandable. (Heck I think this point goes towards all sciences in general).
    .
    The same can be said for the Apollo program. The moon landings captured the public imagination - certainly mine. There was also the political incentive to beat the Russians to the moon in light of the fact that the Russians had achieved all the other space 'firsts' prior to this. Not that we will see that sort of competition again, the trip to Mars will need to be an international effort.

    Incidentally, I had a bit of exchange of emails with an American guy who runs a conspiracy web site running amongst other things, a moon landing denial which in light of recent LRO pictures is in my opinion a lost argument. I really don't understand why anyone would deny such a huge achievement. If it was my country that had achieved this I would be so proud.

    I liked the quote in Neil Armstrongs book 'First Man' where he ranks folks in denial of the Lunar landings along side "flat Earthers and the Elvis lives mob"
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  20. #19  
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    [quote="tszy"]
    Quote Originally Posted by Lynx_Fox
    Quote Originally Posted by Lance Wenban
    IAnother lesson they should have learned is not everything NASA does is about the science. Hubble reached the point of deminishing scientific returns many years ago which is why they tried to shut it down. But they continue to fail to understand that those fantastic pictures, whether they were of scientific interest, generated enormous popularity and interest from tax payers who pay their bills (indirectly). If you want support for large programs than you've got to get past the sterile objective science and make it "sexy," and understandable. (Heck I think this point goes towards all sciences in general).
    .
    The same can be said for the Apollo program. The moon landings captured the public imagination - certainly mine. There was also the political incentive to beat the Russians to the moon in light of the fact that the Russians had achieved all the other space 'firsts' prior to this. Not that we will see that sort of competition again, the trip to Mars will need to be an international effort.

    Incidentally, I had a bit of exchange of emails with an American guy who runs a conspiracy web site running amongst other things, a moon landing denial which in light of recent LRO pictures is in my opinion a lost argument. I really don't understand why anyone would deny such a huge achievement. If it was my country that had achieved this I would be so proud.

    I liked the quote in Neil Armstrongs book 'First Man' where he ranks folks in denial of the Lunar landings along side "flat Earthers and the Elvis lives mob"

    I agree with what you said, however that quote is not mine and I would ask that you edit to correct that. Give Lynx_Fox credit for that quote.
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