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Space Politics

Giant Magellan Telescope Set To Revolutionize Ground-Based Astronomy 105

StartsWithABang writes: If you want to see farther, deeper and at higher resolution than ever before into the Universe, you need four things: the largest aperture possible, the best-quality optical systems and cameras/CCDs, the least interference from the atmosphere, and the analytical techniques and power to make the most of every photon. While the last three have improved tremendously over the past 25 years, telescope size hasn't increased at all. That's all about to change over the next decade, as three telescopes — the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope — are set to take us from 8-10 meter class astronomy to 25-40 meter class. While the latter two are fighting over funding, construction rights and other political concerns, the Giant Magellan Telescope is already under construction, and is poised to be the first in line to begin the future of ground-based astronomy.
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Giant Magellan Telescope Set To Revolutionize Ground-Based Astronomy

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  • by Skewray ( 896393 ) on Saturday February 06, 2016 @01:31PM (#51453275) Homepage
    I certainly see a lot of GMTO articles around the 'net, as opposed to the other two projects. Interesting, that.
    • by Z00L00K ( 682162 )

      At least the interesting part of the article is the references to three different large telescopes.

      What REALLY would be interesting is if someone could put such a large telescope into space. That way we could avoid all atmospheric interference. Of course there would be other problems involved instead.

      • by mikael ( 484 )

        Here's a list of the largest telescopes in space and on the ground:

        http://phys.org/news/2015-01-b... [phys.org]

        The diagram is probably the most informative part of the document:

        http://cdn.phys.org/newman/csz... [phys.org]

        Imagine if both Europe and the USA could build two large telescopes that could be combined together to form a stereoscopic telescope the size of the planet...

        • by KGIII ( 973947 )

          At school, we had a tiny (compared to those) telescope in the observatory. I think it's just a 10" telescope? I used to get stoned and go play in the observatory but I never took any astronomy courses. 'Twas in the Dunn Science Building. I should think it would be kind of fun to use one of these giant ones but I'm damned near positive that they'll never let me have so much as a peek out of one. I'm also positive that I'd have no idea how to use it nor would I know what I was looking at without guidance.

          • by mikael ( 484 )

            I don't think anyone is allowed near those telescopes. They don't have to as everything is accessed through the internet. Each astronomer gets funding for a project. A portion of the funding goes to booking time on a telescope. They specify the target, the time, the telescope, pictures are taken electronically via high-resolution CCD at the eyepiece of the telescope and placed on a server. There are some telescopes which are just continually recording data non-stop to high-capacity RAID array storage packs.

            • by KGIII ( 973947 )

              Yeah, they have sensors that exceed human capacity but that doesn't mean that I'd not like to spend some time at an attached eyepiece. The telescope we had at school (I went to Kents Hill - it's a preparatory school in Central Maine and was what inspired me to return and retire to Maine) had an eyepiece and a camera attachment. (This was in the early 1970s.)

              The modern ones are all just grabbed with sensors and no eyeballs are directly used any more but I understand that all the big telescopes do actually ha

      • by mikael ( 484 )

        Astronomers have found ways to get around atmospheric interference. Amateur or pro-amateur astronomers used lucky imaging [wikipedia.org]. They use a high-speed CCD to catch multiple images of a particular target and keep the ones that are in focus (or even just the bits of image that have a high level of sharpness). Then they can combine these together to make a perfect picture.

        With the larger telescopes, they have adaptive optics to compensate for the refraction caused by air turbulence. They fire off a laser into the sc

    • To me, this is no surprise. The science case [gmto.org] for the GMT is a drool-worthy cornucopia of astrophysics, including formation of stars and planetary systems, properties of exoplanets (including their atmospheres), chemical evolution in stellar populations, dark matter and dark energy (including synergy with the LSST), galaxy formation and evolution, and the first light and reionization of the universe. The potential for observing non-equilibrium chemistry in extrasolar planetary atmospheres is pretty darned e

  • by cruff ( 171569 )
    Once again we get a link to Forbes ...
    • Re: (Score:2, Insightful)

      Yeah, fuck them and their paywall. Didn't read, didn't care enough to try to bypass it. Get used to that, Forbes...

  • The editors of Slashdot should not allow self-promotion. StartsWithABang is Ethan Siegel and we had several of these astronomy and science stories submitted by him that link to his own Forbes articles!
    • Please, half the posters always link to the same sites for any submission .. which means it's all self promotion, or paid shills these days.

      Apparently nobody give a damn ... just like how Nervals' Lobster never posted anything which didn't include a link to Dice.

    • by WSOGMM ( 1460481 ) on Saturday February 06, 2016 @02:13PM (#51453505)

      That's why I skip the articles and just look for the information I'm interested in. Like, hmm, how will this ground-based atmosphere-ridden telescope compare to the Hubble Space Telescope?

      From the FAQ on http://www.gmto.org/ [gmto.org] ... which is linked,

      The GMT will leverage cutting-edge optics technology to combine seven giant mirrors to achieve 10 times the angular resolution of the Hubble Space Telescope in the infrared region of the spectrum.

      When coupled with the GMT adaptive optics (AO) system they will produce images sharper than those from the Hubble or Webb Space Telescopes.

      And it goes on to explain that the atmospheric turbulence 200 meters up can be measured with lasers, and the one of the mirrors is physically deformed to compensate for the measured distortions. Pretty neat.

      • The adaptive optics system is quite something, if it's anything like the one at the LBT on Mt. Graham. They have been able to make diffraction-limited images with that one. When they turned it on for the first time, the results were so good that they thought it must have been an error. The downside is that it took about ten years to make the first adaptive secondary mirror and get it installed, as it's about 1m diameter and 1.6mm thick, with 600 magnets glued to its backside. A couple of them broke in trans
    • by OzPeter ( 195038 ) on Saturday February 06, 2016 @02:17PM (#51453527)

      The editors of Slashdot should not allow self-promotion. StartsWithABang is Ethan Siegel and we had several of these astronomy and science stories submitted by him that link to his own Forbes articles!

      Well given that Forbes doesn't like my ad blocker (and quite a few people on /. run ad blockers for very good reasons) I'd say he's shooting himself in the foot by linking to his own articles on Forbes. He'll never get page views from all of us ad blockers, and eventually someone will post a link to a similar story on an ad blocker friendly site and their page view stats will go up.

      But yeah. Shills still exist on /. no matter what whipslash* has said about cleaning them out, and stories like this always seem to bypass the firehouse.

      *We loved you Whipslash when you spoke about cleaning up /. but when need to see you follow through on this or we will turn on you and opine about "Meet the new boss, same as the old boss".

      • Did the subject get truncated or is that wishful thinking?

        • by KGIII ( 973947 )

          *snickers* Truncated. 50 characters is the max, if I recall correctly. Yes, yes I do suffer for insomnia and the curiosity of a cat. I was curious one late night and counted 'em. Being an insomniac (and hating the way the sleeping pills make me feel when I wake up) and being curious does have some benefits. I'm not entirely sure that counting characters is a benefit -- but this was a curious finding:

          There's an oddity with the character count. If you use the "&" character, it's supplanted by the HTML ent

          • I know about international keyboard layouts, I use UK extended/Welsh for the occasions where I have to write in French.

            Bizarre thing is (on crapdot) that If you quote an excerpt containing a funny character, they get mangled, which doesn't make any sense. Copy/pasted from parent:

            also enables you to type â £ Â¥ and ® with the [...] You can even do diacritics (i think that's what they're called) such as é, Ã, ñ, Ã, ü

            (In preview

            • by KGIII ( 973947 )

              Yeah, it doesn't like it if you do the U+12345 type of method but they like it just fine if you use the layout. The subject bar seems to work the same - except it counts the characters in the HTML entity towards the character count limit. In the body it doesn't matter but if you look at the resulting HTML it's using the entity instead of the character itself - just like in the subject bar, it's just not counted against a total.

              If there's a limit to character counts in the body, I've not met it. I guess I co

  • Pinky: I think so, Brain, but... where are we going to get a Giant Magellan?

  • by jeffb (2.718) ( 1189693 ) on Saturday February 06, 2016 @02:07PM (#51453473)

    It seems like the Moon's surface could be a fantastic place for an absurdly large optical telescope. No significant atmosphere, little or no vibration, low gravity (making for less distortion of the optics), and plentiful raw materials for making fused silica and aluminum surfaces.

    Obvious drawbacks: not a good place for humans, a two-week period of daylight (not necessarily a deal-breaker without an atmosphere, but a source of thermal stress), and a REALLY BIG dust problem.

    • and a REALLY BIG dust problem.

      Is that much of a problem? Doesn't it just stay on the ground?

      • The stuff already there does but there's a lot of incoming dust that'll happily coat anything it lands on. That's a really big problem alright!

      • by careysub ( 976506 ) on Saturday February 06, 2016 @02:40PM (#51453639)

        and a REALLY BIG dust problem.

        Is that much of a problem? Doesn't it just stay on the ground?

        No, it doesn't. [nasa.gov].

      • As careysub already posted with a different link, no, it doesn't [wikipedia.org]. In fact, it appears to rise up and coat things that are left on the lunar surface, darkening them.

        One of the source articles for the Wikipedia entry above [airspacemag.com] talks about this in more detail, but also points out that lunar soil appears to sinter really, really easily when microwaved. It seems like this could be an effective and (via plentiful electricity from sunlight) economical way to "dust-proof" limited regions of the lunar surface. That, co

      • by sosume ( 680416 )

        Speaking of the moon, I really hope they point it at the Apollo landing sites.

        • by ihtoit ( 3393327 )

          it'd be a waste of time, the best ground based telescopes (read: largest) can still only obtain a resolution down to 500m. You're not spotting the landing stage of A11, but under certain conditions (local sunset) you can make out the long shadow it throws. here [space.com] is a shot from the Lunar Reconnaisance Orbiter from an altitude of 15 miles of the A11 site. Note the lack of shadow from the flag - it was blown over by the exhaust from the ascent stage.

          • by KGIII ( 973947 )

            Not necessarily? I just watched the TED talk that was presented by the lady who is kind of in charge of the GMT. I think you're correct, given her verbiage, but we might still be able to detect something. She said that if someone were to light a candle on the moon that the telescope would be able to detect it. Another metric given was that at 200 miles away, you'll be able to clearly make out the face on a quarter. I suspect that you're still correct in that they won't get the resolution they're expecting b

            • It's a fairly easy calculation. A 30m diffraction-limited telescope working in violet light (300nm) has an angular resolution of about 300nm/30m (radians) which is about 10^-8 radians. At the distance of the moon (4 x 10^8 m) that is about 4m, So theoretically the Apollo descent stage might be about 1 pixel across. In reality, I don't think adaptive optics yet allows diffraction limited imaging at such short wavelengths, so I would expect the best achievable resolution to be more like 10m.

              • by KGIII ( 973947 )

                That makes sense. I kind of figured there was a formula to figuring it out - as the lady was quite certain of the abilities prior to the building. Your math and description puts it on par with what I was thinking, I'd listened carefully to the lady's verbiage which was "detect." Much thanks!

      • by ihtoit ( 3393327 )

        there is an extremely tenuous atmosphere on the Moon, which all but doubled in density in the early 1970s - albeit temporarily. It does nothing to slow down interplanetary dust which smacks into the surface at orbital speed. Enough of that plows into a mirror, you've got a wrecked mirror.

    • ...plentiful raw materials for making fused silica and aluminum surfaces.

      Because it is really easy to make a world-class scientific instrument out of dirt?

    • It seems like the Moon's surface could be a fantastic place for an absurdly large optical telescope.

      Put it on the back side and you don't have to worry about any light pollution from the Earth. And, you can also set up a huge radio telescope back there because you won't have to worry about any interference from all of the the Earth's broadcast communications.
    • It seems like the Moon's surface could be a fantastic place for an absurdly large optical telescope.

      I don't see the advantage over just having the telescope in space. And there a numerous disadvantages: the moon's horizon will always obscure half of the sky, the surface will reflect light and pollute the imagery, fixing the base of the telescope means that you will only be able to focus on certain areas of the sky when the moon is in the right position etc.

      and plentiful raw materials for making fused silica and aluminum surfaces.

      There is a notable lack of aluminium smelters and robots to operate them - making the presence of those materials moot.

      It seems to me that the best o

      • The biggest advantage of the Moon is that you can fasten your telescope down and use the mass of the Moon to absorb heat and vibration. In space you need to deal with them. There are also designs for small-scale processing units that will make "mooncrete" from lunar dust (and a small percentage of additives) or extract aluminium, which might be useful for the structure. There are crater bottoms at the South pole of the moon which are in permanent darkness with nearby mountain peaks in permanent light (for p

        • The biggest advantage of the Moon is that you can fasten your telescope down and use the mass of the Moon to absorb heat and vibration.

          Really? I wouldn't have thought the Moon would be any better at absorbing heat than the earth (which is generally terrible at it). Also, what would be generating the heat?

          As for vibrations, what is moving that would cause the telescope to vibrate? Certainly hubble had some vibrations (caused by the doors opening and shutting) but you could get around that by re-designing the doors (or designing them out of equation).

          There are also designs for small-scale processing units that will make "mooncrete" from lunar dust (and a small percentage of additives) or extract aluminium, which might be useful for the structure.

          I've done some research: this [stackexchange.com] is the only site I could find with an actual treatment on h

          • This article explores the pros and cons of the three sites (Antarcita, Moon and L2) in some depth

            http://citeseerx.ist.psu.edu/v... [psu.edu]

            • Very interesting - thank you. The article indicates that a shield would be used to protect the instrument from the sun, and thus allow it to reach 50 K or below. This makes sense. There are some details that don't make sense to me though:

              1. The proposal to use a liquid mirror. If the instrument is cooled to 50K what is the liquid in the liquid mirror made from? It could only be something gaseous at normal temperatures, but there no metallic gases?

              2. The article mentions that the azimuth on the telescope

              • The article seems to discuss a number of different ideas for a Lunar South Pole telescope with different purposes and limitations.

                The liquid mirror idea seems to come from http://science.nasa.gov/scienc... [nasa.gov]. They talk about a non-metallic liquid with a very thin layer of silver leaf (actually solid, but so thin and flexible that it follows the curve of the liquid) as the mirror.

                Since it's at the pole and pointing straight up, tracking isn't really a concern. You can rotate the camera once per month, either

  • I was disappointed when the 100 meter conceptual OWL (Overwhelming Large Telescope [wikipedia.org]) project was abandoned as impractical. Now that would have been cool to have an instrument officially described as "overwhelming large"!

  • by spork invasion ( 4443495 ) on Saturday February 06, 2016 @02:30PM (#51453581)
    For those who don't want to visit Forbes, a site with a history of malware in their ads but insists that visitors disable ad blockers (and script blockers like Noscript)...

    Here are a few links with more information than you'll get from Ethan's article, plus they don't require disabling ad blockers:
    http://www.space.com/31079-giant-magellan-telescope-groundbreaking-travelogue.html [space.com]
    http://gizmodo.com/the-giant-magellan-telescopes-fourth-mirror-melting-is-1736954773 [gizmodo.com]
    http://www.gmto.org/resources/ [gmto.org]

    The technology is pretty damn cool, especially the adaptive optics to deal with atmospheric turbulence. It's worth a read, especially when you don't have to try to visit Forbes.

    I really wish the Slashdot editors would stop letting this crap through. But because they do, it's a good service to everyone if users can provide alternate links that are better. In this case, there's a hell of a lot of good information on the actual GMTO site.
    • I really wish the Slashdot editors would stop letting this crap through.

      Maybe Dice and Forbes have an "arrangement"...

      • by KGIII ( 973947 )

        If you use a browser based on Chromium (I use Opera) you can just copy the URL, paste it into the address bar, and change http:/// [http] to cache:// so, in this case, it is:
        cache://www.forbes.com/sites/startswithabang/2016/02/05/the-future-of-astronomy-the-giant-25-meter-magellan-telescope/#68d3f8536899

        That makes the browser automatically resolve to:
        http://webcache.googleusercont... [googleusercontent.com]

        It takes a minute but both scripts and ads are blocked. It probably wouldn't take a whole lot to automatically do that using GreaseMo

  • by dogvomit ( 979755 ) on Saturday February 06, 2016 @02:35PM (#51453605)

    I was incredibly fortunate to be invited to the official groundbreaking event for the GMT last November, which concluded with one of the most memorable experiences of my life.

    Just a couple of kilometers away from the GMT site are the twin Magellan telescopes [carnegiescience.edu]. These telescopes are both 6.5 meter aperture and have a large number of instruments that astronomers can use, with fairly easy switching between instruments. That night the telescope staff did something extremely rare. They fitted the Clay telescope with an actual eyepiece and all 190 guests were allowed to look through this 6.5 meter telescope! (The president of Chile got to go first, of course.) For this event, the telescope was trained on the saturn nebula [wikipedia.org] and with this much aperture the colors were quite striking even to human eyes.

    One of the astronomers told me that the number of people who have actually looked through such a telescope doubled that night.

    • That's... amazing. Color me incredibly jealous.

      I'd guess they were throwing away nearly all that aperture -- to get all the scope's light through a 4mm exit pupil, you'd need close to 2000x magnification, which would make the nebula look like it was about 24 degrees across -- okay, that would fit perfectly into a normal field of view.

      So, yeah. I hate you even more.

      (Wonder what kind of 4mm lens could successfully catch all the light from a system that size? It's been a long, long time since I was immersed in

      • The guy who was running admitted he thought they were wasting about half the aperture. I didn't want to think about that; I just wanted to drool over getting to look through such an instrument! :-).

      • by amorsen ( 7485 )

        Somehow I think they picked the nebula because it happened to fill the field of view...

      • by Skewray ( 896393 )

        That's... amazing. Color me incredibly jealous.

        I'd guess they were throwing away nearly all that aperture -- to get all the scope's light through a 4mm exit pupil, you'd need close to 2000x magnification, which would make the nebula look like it was about 24 degrees across -- okay, that would fit perfectly into a normal field of view.

        So, yeah. I hate you even more.

        (Wonder what kind of 4mm lens could successfully catch all the light from a system that size? It's been a long, long time since I was immersed in the amateur-telescope-maker literature...)

        The exit pupil of the eyepiece is probably more like 20 mm, so that the observers don't have to get their eye exactly in the right place. Wastes a lot of light. I was there last time they put an eye piece on Magellan. I remember being able to spot four moons by moving my eye around, but I no longer remember if it was Jupiter or Saturn.

    • by Anonymous Coward

      Wow, how reckless. With that kind of aperture, a passing plane or meteor will blind a human for life, which is the actual reason why eyepieces are never fitted to 6.5 meter telescopes.

      • by jeffb (2.718) ( 1189693 ) on Saturday February 06, 2016 @10:31PM (#51455315)

        No. No, they won't.

        Think about the distance to an airplane in flight. Next, think about the area of the sphere with that radius, and how little of that area even a giant telescope's mirror will intercept. You're not going to be blinded. You might be surprised, and you might lose your dark adaptation, but you're not going to be blinded.

        Now, think about the area subtended by the telescope's field of view -- in the example above, a circle perhaps one minute of arc in diameter. What are the odds that a bright meteor will pass through that area during an observing session, slowly enough to linger long enough to cause damage? Pretty darn tiny. (Your odds may actually be worse if you aren't using the telescope, because then you're more vulnerable to a really bright meteor crossing your wide native field of view.)

        The "real reason" eyepieces are rarely fitted to huge telescopes is because it's wasteful. The human eye is much less sensitive than the instruments normally fitted to such a telescope, and it doesn't record its perceptions for later analysis. Demand for real scientific observations from a large telescope always exceeds available time, so nobody wants to waste the machine's capability for some momentary sensual gratification.

        As for safety, until planes are outfitted with multi-watt lasers specifically targeting telescope facilities, or until we're ambushed by a dense swarm of very bright meteors again targeting telescopes (so their apparent motion is slow enough to make them linger in a tiny field of view), our visual observers are pretty darn safe.

        Besides, you only look through the eyepiece with one eye at a time, so you'll have a spare...

    • I recently got a tour of the 200 inch Hale telescope, which is outfitted with an optical eyepiece, although it was daytime so I didn't get to peek through it. My have to stop by at night some time to do so. (It helps if you know the site supervisor or one of the astronomers.)
  • you need four things: the largest aperture possible, the best-quality optical systems and cameras/CCDs, the least interference from the atmosphere, and the analytical techniques and power to make the most of every photon

    Nope, you only need the best acquisition method possible to get out the most information per photon. This is not equivalent to having the best CCD camera or the best optical system. It actually can be the opposite now that we have a lot of processing capabilities (of both light beams and digital imaging).
    We can, for instance, make high resolution images from low resolution sensors while being less sensitive to noise; or even introducing known aberrations in the system to correct for the shortcomings of trad

  • by ndverdo ( 799508 )

    The European Extremely Large Telescope (ELT) is already under construction, no political BS, and with 39m diameter a much larger class than the 26m GMT's .

  • GMT's approach of using a small number of very large round mirrors, instead of a large number of small hexagonal ones, is very different from the path chosen by E-ELT and TMT (and GTC, and SALT, and HET, and Keck I and II)... in fact, other than possibly the original design of the MMT, I'm unsure whether anyone's done this before. (And of course the original design of the MMT was chosen because nobody knew how to make a 6.5-meter mirror at that point in time.) It will be very interesting to see how well i

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