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Giant Magellan Telescope Set To Revolutionize Ground-Based Astronomy
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.
I certainly see a lot of GMTO articles around the 'net, as opposed to the other two projects. Interesting, that.
Once again we get a link to Forbes ...
We should really ask Bennet Haselton about this.
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!
It's a cool idea, no doubt. But no matter how good your telescope is, I doubt it can easily surpass observing systems in space like the Hubble. At its altitude, roughly 25% of the atmosphere is beneath it, which reduces the problem of scintillation. Furthermore, the position in the Atacama Desert means it's a dry place, so there isn't a big problem with moisture causing differences in air density, leading to scintillation or even just refraction by the atmosphere. That said, why in Chile? Why not in Tibet, where it could be positioned at an even higher altitude but with many of the same favorable characteristics of being dry and away from light and air pollution? I recognize that it just isn't possible to build an observatory at the summit of one of the higher Andean peaks, but Tibet is probably a better place. That said, why don't we have plans (that I know of) for a replacement for the aging Hubble?
Pinky: I think so, Brain, but... where are we going to get a Giant Magellan?
You're another asswipe who doesn't know a Magellan from a TMT. Hawaiians have a word for people like you: Haole. Just saying. Must suck to be you.
-- "I'm not in a hurry; I'm in Hawaii." The Homeless Guy
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.
Lost at C:>. Found at C.
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.
I was disappointed when the 100 meter conceptual OWL (Overwhelming Large Telescope) project was abandoned as impractical. Now that would have been cool to have an instrument officially described as "overwhelming large"!
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
and a REALLY BIG dust problem.
Is that much of a problem? Doesn't it just stay on the ground?
systemd is Roko's Basilisk.
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/ ... 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 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!
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".
I am Slashdot. Are you Slashdot as well?
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
http://gizmodo.com/the-giant-magellan-telescopes-fourth-mirror-melting-is-1736954773
http://www.gmto.org/resources/
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 hate all anonymous shitbags. Log in, you filthy bastards.
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. 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 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.
...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?
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
and a REALLY BIG dust problem.
Is that much of a problem? Doesn't it just stay on the ground?
No, it doesn't..
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
You're dealing with a Space Nutter. Just pretend his posts are the enthusiastic crayon scribblings of an 8 year old.
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 traditional imaging techniques.
That's pretty much what world-class scientific instruments are made from. Of course, there are a lot of intermediate steps. (I should also point out that "really easy" are your words, not mine.)
Lunar dust is the main deal-breaker from us setting up Anarctic-style science facilities there. There is no weather abrasion, so the lunar dust is like massive piles of the best abrasive known to man. Your "hoverboard" will fail catastrophically there.
There you are. I figured you were sleeping late.
As careysub already posted with a different link, no, it doesn't. 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 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, coupled with a fairly simple static-charged chicken-wire fence to divert or intercept laterally-propelled dust, might well make the problem manageable.
True, but the instrument you mean is the TMT. Having been rejected by Hawaii, the project now has to find a new home. It must be in the norther hemisphere so that long baseline observations can be performed as a twin to the Magellan.
One longshot tactic for getting it built in the original location remains: legalize pot in Hawaii.
There you are. I figured you were sleeping late.
He was milking those cows.
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 .
The dust particles levitate because of electric charge. It could be possible to electrically charge the mirror of a telescope to repel them, and/or make a charged dust collector that encircles the telescope's aperture and catches the dust as is enters.
Speaking of the moon, I really hope they point it at the Apollo landing sites.
Did the subject get truncated or is that wishful thinking?
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Obvious drawbacks
You forgot: no atmosphere also means no protection against micrometeorites, and nothing to slow them down.
A grain of sand can shatter a mirror when it hits at a few miles per second.
High speed impacts of small objects don't shatter large optics, they implant and leave a small, linear defect. Instruments already in space are designed with this in mind. Unless you built you mirror poorly, it won't have enough stress to shatter without a massive impact of any kind.
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.
Good, inexpensive web hosting
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.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
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 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.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
every instrument made out of glass was once just handful of sand.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
At least it wasn't his own articles (or at least I think they weren't - I never checked) and they had actually had some kind of "news" content about them.Somewhat the same with Hugh Pickens who often linked to the NYT. Where the fuck is whipslash on this?
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 transit before they figured out how to pack them properly. (I work in the same building as the GMT and the LBT folks.)
The determined Real Programmer can write Fortran programs in any language.
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 option would be put the telescope on a higher higher solar orbit than the earth. This way, you can get imagery (mostly) without light pollution and objects in the way. The main disadvantage is that should the telescope need repairing it might be a year or so before robots could be launched to repair it.
http://jwst.nasa.gov/
It is going to be Huge! If it all goes to plan... The video simulation of deployment looks pretty complicated.
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 it works, particular in comparison to the (by now well-established) practice of using lots of small hexagons.
Village idiot in some extremely smart villages.
There is no suggestion or prospect of doing long baseline optical interferometry with any of these telescopes, mainly because no one knows how to do it. Optical interferomteres cover at most 100m or so.
The reason for wanting one of these telescopes in the Northern hemisphere is simply so it can see the Northern sky.
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 power collection).
You also have the prospect of astronauts visiting if you need repairs/upgrades your robot can;t do.
Earth-sun L2 (where Gaia) is, is the other serious contender -- a very stable environment, but out of reach for humans and requiring a little fuel for station-keeping.
The ariticle I read about these in also mentioned the top of the Dome A in antarctica as a serious contender -- very still dry cold air all winter, compacted snow as a building material and relatively cheap and hospitable for humans.
I'll give 'em all the acreage they want in NW Maine and let 'em flatten a mountain top to do it. I ask only that they pipe a feed to my house via fiber and occasionally let me take a peek out of it. However, I'm pretty sure they don't want to put it there considering that it's up above the 45th and the mountains aren't exactly very tall as glaciers have worn 'em to stumps over the years.
And no, there are no glaciers currently in Maine. Yes, yes I have been asked that question.
"So long and thanks for all the fish."
*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 entity (which, oddly, contains the ampersand) and the entity is counted against the limit. So, it is "& amp ;" (sans spaces) to make & which is four extra characters, or counts as five characters against the fifty character limit.
I seem to recall that the other whitelisted entities are processed the same way. So "& copy ;" (also sans spaces and to make ©)* would actually count as six characters, which means a total of five extra characters being counted against the limit.
However, to the point! Err... I don't have a really good point but... What you did there? I see it.
* If you use an International Keyboard Layout then you can just insert the © symbol by using the appropriate shortcuts. In this layout it is Right ALT + C. It also enables you to type € £ ¥ and ® with the use of the Right ALT or Right Alt + Shift, depending on the desired symbol. You can even do diacritics (i think that's what they're called) such as é, í, ñ, ú, ü, and whatever else is whitelisted by the overlords. However, Rei's "thorn" does not work. If one does not wish to use the alternative keyboard layouts then you can click here** and use the table to find the HTML entity.
** No, using the target="_blank" does not work so that will open in the same tab/window, even if I told it to open in a new window/tab. No, I have no idea why that is stripped out.
"So long and thanks for all the fish."
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 but they might be able to make out something - adaptive optics and whatnot might help that to some extent.
Probably salient, the particular verbiage used. She didn't say they'd be able to see the candle but that they'd be able to "detect it." What that means, exactly, is not something that I know. I also lack the expertise to speculate on the clarity. But, I suppose, perhaps they'll be able to make out some of the larger items that were left behind? I really have no idea and only know what I know 'cause I watched the TED talk.
Also, I'm not sure what the value of that would be. The goal is to look at things with scientific value with the telescope and there are surely time constraints. There's limited value in it when we've already got the ability to look at it with closer telescopes. Not even the Hubble can see the landing sites but this is supposed to be significantly higher resolution. If I understand correctly, it's the size and the added light that they're able to collect.
"So long and thanks for all the fish."
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:
(In preview they're showing as various uppercase A variants.)
I'll type some direct:
MÃtÃrhead, HÃgar the Horrible, chÃteau.
I also suspect that the subject line sometimes acts differently to the body. But heck, I can't be bothered debugging my own shit, why would I bother with whipdice's?
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
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 is the only site I could find with an actual treatment on how aluminium extraction would work: in short, exactly as it does on earth, a process with a prohibitively high energy budget.
There are crater bottoms at the South pole of the moon which are in permanent darkness with nearby mountain peaks in permanent light (for power collection).
But again, wouldn't placing a telescope in a crater mean that a large portion of the sky is blocked by the moon?
You also have the prospect of astronauts visiting if you need repairs/upgrades your robot can;t do.
Hard to imagine a repair that a robot couldn't perform better than an astronaut - it is actually quite difficult for humans to operate on things in space, owing to the impediment of the suit.
Earth-sun L2 (where Gaia) is, is the other serious contender -- a very stable environment, but out of reach for humans and requiring a little fuel for station-keeping.
True, but then there's no reason for humans to go there (or anywhere in space other than LEO, come to think of it). An Ion engine might suffice to keep it in place for a reasonable time. Perhaps if we had a collection of craft nearby they could be refueled by a refueling drone of some sort.
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 could test for it. I just might do that the next time I'm that bored. However, when you hit reply and then hit quote parent, it converts then back to what the original poster used. That sentence is as clear as a mud-puddle when I read it.
If you hit reply and quote the parent text using the quote parent button it quotes what was actually typed. Meaning, if I typed © with the keyboard, it will just show the symbol in the body text input field. If I used the HTML entity, © (& copy ; but without the spaces), and you quote the parent then it will show the actual HTML entity that I typed out. In both cases, the resulting HTML entity is used in the resulting page. So, if you view source, you'll see the "& copy ;" entity used no matter what method I used type it.
So, that's still about as clear as mud. Yeah, that's as good as it's gonna get as for an explanation for me. I'm just not that articulate. ;-) It's also just an observation and I have no idea why. It also seems to matter if you copy/paste but not always and I've not yet figured out the mechanism for that. I've just not yet been that bored. It could happen but I'm pretty sure that entropy is my natural state so it's a bit unlikely. I only discovered the above because I'd seen the very truncated subject lines that contained the ampersand. That was enough to overcome my lethargy.
Like you alluded to, 'snot our problem. It's whipslash's problem now and I wish 'em luck with it.
"So long and thanks for all the fish."
gstoddart, you've been asked, repeatedly, to spare us your simian thought patterns put to written words from your mongoloid cretin's doltish brain!
LOL, don't you usually spend Sunday mornings in a gimp suit bent over a saw horse?
Lost at C:>. Found at C.
Ah, yet more crude unoriginal simian mentality level scribblings from the dim cretinish monogoloid brain of gstoddart housed in his microcephalic skull case!
Hahahahahahahahaha
gstoddart, your dim cretinish dolt brain reveals truths about you yet again in projecting your own strange habits. How's that go with your cheerios there, mongoloid? Hahahahaha!
It's rather obvious you do gstoddart. Doesn't it make drinking your coffee a mess once ole' gimp starts pumping you giving you that home made high colonic you like? ROTFLMAO!
This article explores the pros and cons of the three sites (Antarcita, Moon and L2) in some depth
http://citeseerx.ist.psu.edu/v...
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.
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!
"So long and thanks for all the fish."