Slashdot Mirror
Telescope Will Have Images 10X Sharper Than Hubble
jangobongo writes "After a 20 year struggle, the University of Arizona's $120 million Large Binocular Telescope was dedicated last week. This unique telescope will have twin 8.4-meter (27.6 foot) mirrors that sit on a single mount. Using methods similar to a medical CAT scan, a technique of "tomographic" image reconstruction will be used to produce pictures 10 times sharper (example) than the Hubble Space Telescope for a fraction of its $2 billion dollar cost."
I don't really think it's fair to compare this with the hubble, unless this telescope can orbit earth.
Here is a particularly good description of the LBT (Large Binocular Telescope) from an article in the Eastern Arizona Courier.
The LBT is made up of two 8.4-meter mirrors, which, when in place, will bring together the light, creating sharper images of faint objects in space. One mirror is in place at the Mount Graham International Observatory, and the other will arrive next spring. Each mirror is designed in a manner that allows it to reach the same temperature as the outside air up to two hours faster than any other mirror design. Under the solid glass surface are openings in a honeycomb pattern. Cold air is pushed up through those openings, cooling the glass to the desired temperature. The sooner the glass cools, the more science can get done, which is good from a business standpoint, assistant project director for LBT Jim Slagle said.
Not everbody is happy about this, though. The Apache people are protesting the use of the site for the telescope.
The U of A is finally dedicating it's Large Binocular Telescope (LBT), formerly called the Columbus Project, after years legal and money problems and at least a year before actual completion. (The U of A changed the name of the project after realizing it wasn't such a popular idea to name it the Columbus project and then, against the wills of the Apache people, place it on their most sacred site on top of the mountain.) The LBT is mainstay of the project. Investors will be wined and dined on Fri. at the La Paloma resort in the Catalina foothills and bused up to the mountain on Sat. to tour the scope site. Our job is to show the investors how controversial and unpopular this project is... and has been for decades.
http://www.busyweather.com/
A space-based telescope (like the Hubble) can be rotated and aimed at almost any object out there. In that sense, a Hubble is still superior in some aspects.
On the other hand, just the fact that adaptive optics and interferometry can clean up the images so spectacularly is simply amazing!
I wonder how long before I can get a consumer-grade version, to take pictures of the coeds^H^H^H^H <ahem> natural "scenery"... ;-)
"Seeing" is the wobbling back and forth of portions of an image caused by the turbulence of the atmosphere. The many "seeing cells" above a telescope act as lots of little lenses and distort an image taken from the ground. In general, the best sites in the world can sometimes allow "seeing"-limited observing down to around 0.2-0.4" (that is the best resolution possible -- which is much less than would be possible with a large telescope in space). However, adaptive optics (or interferometry) can sometimes beat this atmospheric limitation.
And yes, IAAA (I am an astronomer).
Seeing limited means limited by the turbulence in the Earth's atmosphere. There are lots of cells of turbulent air in the upper atmosphere that make the stars twinkle -- this is the bane of ground based observing. The whole point of putting a telescope in space (at least in the optical bands) is to avoid this 'twinkling' effect. Astronomers call this seeing, and go to great lengths to try to build telescopes in places (like Hawaii, Chile, etc.) where the seeing is good. Good seeing usually means about 1 arcsecond -- this is much better than what you see when you go out in your backyard in most places. Pretty exceptional seeing is 0.5 arcseconds or better. HST, which is above the atmosphere, is not limited by seeing, but IS limited by the size of it's mirror. Because of the wave nature of light, every telescope has a limit on how sharply resolved it's images can be based on the diameter of the telescope. A ground based large telescope, like Keck or the LBT, would always have better image quality that Hubble IF you could get that pesky atmosphere out of the way.
Now, in the past few years something called adaptive optics has become popular. It consists of techniques to correct for the twinkling and make the big, ground based telescopes, see more clearly (in some sense) than HST. The problem is that this only works in the infrared -- not in the optical bands. So we can now do better in some ways from the ground than in space, but not at all wavelengths.
The claim that the LBT is x times better than Hubble is somewhat misleading. Again, this only applies to the infrared -- NOT the optical. And even in the infrared the story isn't really that simple -- with adaptive optics (at least) you tend to get a narrow core that is really, really well defined, much better than Hubble, but then there is a large skirt of less corrected light around the sharply defined core. So for some purposes adaptive optics isn't really better -- like if you need to measure all of the light. This is (naturally) being worked on.
Another problem is that for most adaptive optics systems you need to have a pretty bright star right next to what you are looking at -- which isn't true for most parts of the sky. People are bulding laser systems that create artificial bright stars wherever they want to look, but they aren't as common, don't work as well, and are difficult to use -- among other things you have to file an observing plan with the FAA to make sure you don't accidentally shine the thing at a plane flying by.
You shouldn't have this problem with the LBT, but I don't know about the previous one. And, as far as I can tell, it also only works in the infrared.
> This isn't intended to be a troll, but I just don't get space exploration. I mean, there are a lot of good causes that all these dollars could be going to right here on Earth: stopping wars, battling diseases, increasing literacy, fighting pollution.
Better yet, why not use the money we spend on wars for all that good stuff, and maybe we'll have enough left to do some space exploration anyway.
Sheesh, evil *and* a jerk. -- Jade
"theres not air in space..."
But there's an Air in Space Museum?
Unknown host pong.
I spy, with my $120m eye...
something black and vacuous!
It's only a model.
(I forgot to log in last time so I'm reposting this under my account this time... D'oh!)
You forgot Spitzer (Link), which is up there today. There have already been more than a few collaborative projects between this space telescope and Hubble.
And on the subject of space telescopes that can see places Earth-based telescopes will never be able to see because of the blocking effects of the atmosphere: Chandra (Link), which can see X-ray sources. This one is my favorite Chandra picture.
--- Journals are boring; Go to my web page instead
The story gives the impression that the LBT will completely replace Hubble, and do a better job, while being vastly cheaper.
This is an overstatement. There is lots that Hubble can do that no other telescope can, being a unique combination of aperature (light gathering power and resolution), instruments (many wavelengths, imaging and spectroscopic) and being above the atmosphere (no 'seeing', no atmospheric absorption or emission in UV and IR.)
(This is not to downplay the LBT - doing better than HST in some aspects, and as well but much cheaper in others, is very valuable.)
Having quickly scanned the website for this telescope, I can't see how they are counteracting the bluring of 'seeing' (atmospheric turbulance). It is inconceivable that they have neglected it, but I don't see where. Adaptive optics can help, but have limitations of their own.
Another limitation of the LBT is that the high resolution reconstruction will require 3 observations at different times - so it only works well with non-time-varying targets. This is a minor limitation, however - a large majority of targets for which you want high resolution are non-variable.
(IWAA: I was an astonomer. PhD, but no further.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
It will permit formation of images of sufficient sharpness (diffraction-limited) that the planet could be detected against only a low surface brightness halo of residual scattered light. In this manner, a Jupiter-like planet could be detected, if present, around some fifty of the nearest stars. The interferometric mode will enhance the planet/background contrast even further, thus increasing the number of candidate stars and the sensitivity of the survey. The direct detection of such a planet would surely be counted as one of the major steps forward in determining the likelihood of life existing elsewhere in the Universe and in understanding our place in it.
So, gas giants, but no mention of anything Earth-like. Too bad. I'd definitely be psyched to someday hear about "Earth-sized planet discovered about an AU away from a Sun-sized star."
The instruments in the Hubble are likely to be damaged by the brightness of the Earth.
But don't worry, the Keyhole scopes the US intelligence community use are basically Hubbles pointing at the earth, with appropriate instruments. Of course they don't let anyone see the pictures or admit they exist, but that's a minor detail.
Actually I think you are missing something... NASA was is space in the 60's. Private enterprise only made it in '04 because someone was willing to throw a lot of money at a prize. In fact NASA works with private enterprise on almost everything it does,,, it just happens to be very expensive doing it first.
but as an astronomer,
/me ducks
so, you took up space in college eh?
"goodbye and hello, as always" ~Prince Corwin, from Zelazny's Amber series
Well, you have to realize, the Hubble is very, very old technology. It was actually completed in 1985, although it wasn't launched until 1990, because of the Challenger disaster.
With that TWENTY YEAR OLD technology, we have gotten absolutely amazing results, as you have seen. After two decades of advancement, we can do even better from the ground, but that doesn't invalidate the science we have already done. (like that huge meteor strike on Jupiter; because of the Hubble, we practically had front-row seats). The money involved to keep Hubble running isn't that large, relatively speaking; the initial build and launch were very expensive, but we have already paid for those. Fixing the Hubble just needs to be cheaper than building a ground-based 'scope of similar quality, and I don't think there's any argument about that. And even if the Arizona telescope is better, that hardly makes the Hubble useless. There's never enough observation time for everyone on the really big instruments, and having several available would be good.
The Hubble's successor should be as far past its ground-based competition as the Hubble was. Like it or not, that atmosphere is annoying: we can correct for its presence to some degree (which we couldn't twenty years ago), but it's even better to not have it in the way. We're trying to look unbelievably far away, and if we're not spending a great deal of time correcting for the atmosphere, we can spend time correcting for much smaller problems.... ultimately giving us far better pictures.
Reemember the Hubble Deep Field -- in the darkest part of the sky, in an area about as large as a grain of sand held at arm's length, we saw at least 1,500 GALAXIES.
There's a lot to see out there.
A requirement on all observing proposals to Hubble is that the observation can't be done by any ground based telescope. This is so we don't waste the expensive telescope time on something that can be done by the chearper telescopes. So when LBT starts operation, there may be some observations that would have been done on Hubble going to LBT instead. But certainly not all of them.
In any case, the way things are going at NASA HQ, it'll be lucky if Hubble is still operating by the time LBT starts observing with both mirrors.
First, all "these dollars" are spent right here on earth anyway. The idea that somehow or other money spent on research for space or technology is gone when the space craft is launched seems to be a common fallacy. It is also a faovorite that is often promulgated by parties with an interest in keeping frontiers closed and humanity in bulk pig-ignorant (religious zealots, some political parties, etc.).
Second, I doubt that any amount of spending will "stop" a war. Wars are inherently economic at root. A Cheney or a bin Laden or a Bush, a Haliburton or an Enron is always, always in the background with an "interest" in the objective of any conflict. Ideals and religious rationalizations are used by all sides in a war, but curiously, neither the idealists nor the religious seem to supply more than cannon fodder. The commonest example of this these days are the leaders of Muslim terrortist groups. You don't see THEM with a pound of semtex strapped to their bodies, or out taking lessons in crashing airliners. Nope, its some poor sap with a burning desire to purify the land for his religion or to get even for a real or imagined harm done by some equyally misguided zealot on the other side. What would stop wars is for the "followers" to hand their leaders the bag and say, "O.K. boss, your turn."
------ The only greater hazard to your liberty than n politicians is n+1 politicians.
The radius of the earth is about 6400 km, and hubble only orbits about about 570 km above that. If you do the trig, hubble only has a 225 deg feild of view at any one time compared to 180 on the earth (disregarding the atmosphere in both cases).
Furthermore, both hubble and an earth bound telescop would have a somewhat limited view due to their "orbit". Concider a telescope on the equator. It would have a 180 degree field of view at any given time, and over the course of a day, everything would be in it's field of view except a cylinder the width of the earth, centering around the earths rotational axis, and extending to infinity in either direction. If you have telescope further north, it's daily field of view would have a cone shaped blind spot to the south. Hubbles orbital blind spot would be nearly non-existant over its orbit period, slightly better than the observatory at the equator, but that is easily solved by having two observatories - one in each hemisphere.
Concidering how inexpensive these are to build relative to a space based telescope, there is no reason why we can't do this. In fact we have hundreds of observatories across the world, each new or improved one slightly better than the one befores, but only one space based telescope. Improvements in ground telescopes will also be available to many more researchers, than with just one expensive space telescope.
I have seen several stories of telescopes that promise equal-or-better than hubble images. Usually there are some drawbacks. Here are some of the drawbacks that came up:
1. Limited range of sky
2. Frequencies different than hubble, such as only infrared.
3. Only works near bright stars due to "guide-star" anti-blur technology.
Let's see if new techniques get around these.
Table-ized A.I.
With that TWENTY YEAR OLD technology, we have gotten absolutely amazing results,
Some of it has been upgrade by shuttle service missions.
Table-ized A.I.
Oh for heaven's sakes, this would have taken you maybe five seconds to check online.
The NRAO's headquarters are in Charlottesville, Virginia, and have been for a very long time.
The NRAO has facilities in a variety of locations, of which Green Bank is one.
The two 8.4 meter (331 inch) diameter primary mirrors are mounted with a 14.4-meter center-center separation.
Nobody's eyes are that far apart.
You're using her as bait, Master!
I am only an ameteur astronomer but wouldn't a more valid comparison be to (the slightly lesser known) Keck Telescopes on Mauna Kea? For those of you who are not familiar there are twin 10-meter telescopes on Mauna Kea, which I'd be willing to be has infinitely better seeing (read: atmospheric conditions; the light is distorted less) than New Mexico.
In addition, one can add instrumentation and the like to ground based telescopes and not really to space based onces - hence, Keck would be a much better comparison.
Finally, I don't understand why such a big deal is made of the implied revolutionary methods that are used to combine the images from each scope. If anyone knows, is this different from any other dual telescope setup?
The basic limitation to the size of a telescope you can take off the Earth's surface is the diameter of the launch vehicle, not platform stability. For reference, Hubble's primary mirror is 2.4m diameter, and the shuttle's bay (largest payload capacity available, I believe?) is 4.5m across.
;)
Future space telescope concepts include deployable mirrors and such.
The moon's only advantage would be if you had a mirror manufacturing facility there, which clearly isn't going to happen anytime soon.
Every space-exploration article draws this kind of post that says, "but we have more important problems here on Earth we should spend the money on."
And would spending the money spent on space actually fix these problems? No. There's enough food in the world, to take one problem, but other issues (politics) interfere with distribution.
This criticism can be reduced to the absurd very easily. In the most extreme case, should we identify the "top priority problem" and spend 100% of our resources to fix it? And then move down some list?
Of course not. That notion is absurd.
The case for space expoloration is exactly the case as for basic research of any kind. You never know what you will discover or its importance until you do it, and supporting basic capability in science and technology is always a good idea for a society. It pays off economically in lots of ways, so it doesn't even cost what it looks like on paper.
Personally, I find it gratifying to live in a culture that values studying the universe and understanding our place within it. That says something noble about humans in a world that is too often filled with the mundane and the tragic.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
Well, almost all. There are a couple of difficulties with respect to pointing. Even under a sixth of normal gravity, you still need a much beefier structure to rigidly support a telescope on the Moon, compared to the same object in space. Particularly when the direction of that gravitational force changes as you tilt the telescope to follow objects.
In principle, you could build a space telescope of hundreds of meters in diameter, and it wouldn't sag. You'd have to brace it a bit for aiming motions, but you can do those at a hundredth of a gee, not a sixth--and the stress is off again once you're aimed.
For a really big telescope, that's another advantage of being in space--you don't have to move it while imaging. Point it, and it keeps looking at the same object for as long as you want to integrate. On the Moon, you have to track objects across the sky.
The ESA's Darwin project proposes a free-flying array of six(!) 1.5 meter telescopes up to five hundred meters apart, with their relative positions controlled to within micrometers to do optical interferometry. They want to be able to do things like 40 day exposures to measure the spectra of extrasolar planets and possibly detect life. I don't mean to suggest that such a facility isn't possible on the Moon, but assembling and reconfiguring it (if necessary) is probably a lot easier in space where you don't have to pour concrete foundations.
~Idarubicin
The size of a telescope's primary mirror determines its lighter gathering property (LGP). The larger the primary mirror, the more light it collects and thus the more light over a period of time it collects. The Hubble only has a 2.4m (94.5") primrary mirror, the LBT has two 8.4m (331") mirrors that combined act as a single circular 11.8m (465") mirror.
The LBT therefore collects far more light per unit of time than Hubble does. For many types of imaging the LBT ought to be able to get Hubble-quality or better images in less time than it takes Hubble to get them. A four day exposure from Hubble might only take a single day on the LBT.
This however doesn't necessarily answer the question of how far the LBT can see. Hubble is in an enviable position of being extra atmospheric. It can image in parts of the spectrum that are entirely blocked out by the various gasses floating around here on Earth. Hubble is able to take those deep universe images by imaging mostly in the IR band of the spectrum. Galaxies billions upon billions of lightyears away have enormous amounts of redshift. What they originally emitted in visible light has stretched into infrared as it's traveled to reach us. The pretty images NASA releases are just that, pretty images. They're greyscale images that have been given false colors as to be more appealing to non-astronomers.
Hubble will still be able to peer deeper into space than the LBT. The LBT however will be able to image faint visual objects quicker than Hubble (in many cases) and get far better optical resolution of large cosmological structures. A small telescope on the ground might be able to see M31 (the Andromeda galaxy). Hubble might be able to see fairly large structures like globular clusters, large dust clouds, and larger groups of stars. The LBT however will be able to see even smaller structures than Hubble. With higher resolving power the LBT will be able to produce more detailed visual band images which can be combined with other images or studies (Hubble IR or UV images for example) to provide a ton of information about the structure of that galaxy. The LBT isn't designed so much to replace Hubble or anything else, simply to expand our capability to observe and study objects in the sky.
I'm a loner Dottie, a Rebel.
The moon isn't that great a place to build a telescope -- it isn't as stable a platform as being in space-- things hit it and shake it, and there's dust falling all over. You also have the problem of having to land everything gently as it drops into the moon's gravity well, which ends up costing you more energy. You're also in a varying thermal and solar environment, which is hard on equipment and decreases throughput.
Heliocentric orbits (e.g. earth trailing) or the Lagrange points (cue ZZ top) are nicer, more stable environments to put your space telescope into.
There's an article Buyer s guide to telescopes at the best sites which considers deep space lunar and Antartica locations in detail. All have pros and cons.