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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."
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/
Because to build a space based telescope costs a lot more money than a ground based one. Not to mention launch and maintenance costs associated with something like hubble.
http://en.wikipedia.org/wiki/Seeing_(astronomy)
{googled "seeing astronomy" wikipedia link was on second page of links that Google returned )
"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.
I think you answered all of your own questions. You can't compensate for the atmosphere completely, but its a lot cheaper to build a really huge telescope on the ground than in space. I have a feeling they will go with the best price-performance ratio. If you could convince someone to cough up a cool $10 billion for a cutting edge telescope I'm sure they would do it. I'd chip in but I'm about $10.000005 short.
Did you look at the comparison in the summary?
Karma: Segmentation fault (tried to dereference a null post)
I'd suspect it would have something to do with it not being able to focus that close. Just like if you point a camera at something 5 cm in front of the lens, it wouldn't be able to focus on it, and you'd get a really fuzzy picture.
You are referring to JWST (James Web Space Telescope), which is still ~7 years from launch (my guess is more like 10, but at least they have a design now).
Doug
Venn ist das nurnstuck git und Slotermeyer? Ya! Beigerhund das oder die Flipperwaldt gersput!
Adaptive optics is great but what about UV and IR spectrography and imaging? One of the HST's best features is the ability to image and get spectrums from UV all the way to IR. Ground based telescopes only get a fraction of the spectrographic information the HST receives. A great deal of the recent information regarding supernovae has come from UV images and spectra from the HST as have excellent H2 and dust maps of our own galaxy. For cosmological structure observations ground based telescopes with adaptive optics can be wonderful tools but at the same time there is a definite need for observatories outside of the atmosphere.
I'm a loner Dottie, a Rebel.
Sadly, I'm not qualified for any of them.
Win a signed Stephen Carpenter ESP Guitar from the Deftones: http://def-tag.com/?r=0008781
the earth rotates too quickly to begin with, the hubble's minimum exposure time is 1/10th of a second, and hence the earth will have rotated a large distance in that time; in addition to hubble moving, since it orbits aproximately once every 100 minutes. also, it might be slightly too close to get good definition of its target
In the future, we will all be very smart or very stupid.
Agreed, it's not a completely fair comparison. Adaptive optics and interferometry technology on ground-based telescopes will be great advances but they can only operate at near-infrared wavelengths and only create images over a very tiny field of view. Hubble has the advantages of being able to observe in the UV and visible and to have a completely stable image quality, which you would not get from the ground even with adaptive optics. There are still a great variety of scientific projects that can only currently be done with Hubble. It would be really inaccurate to claim that these kinds of ground-based imaging technologies can replace the diverse capabilities of Hubble.
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."
Sorry to say it, but it's already done.
The horizon limits you to viewing half the sky. Atmospheric effects make it difficult/unviable to view close to the horizon, so in practice this is even more limited - say 1/3 of the sky. In addition, daylight restricts your observing time by a factor of more than two, and for faint diffuse objects (glaxies, nebulae) you also can't observe when a bright moon is in the sky, nor, of course, when it is cloudy - so maybe you end up with 4 hours per day of good observing time per night, on average. A space telescope suffers none of these limitations. (Well, just a little - you can't observe too close to the sun, moon or earth.)
However, although you can only observe 1/3 of the sky at a given moment, the motion of the stars through the night and year means you can observe much more of the sky if you're prepared to wait. Furthermore, if the telescope costs a small fraction of the cost of a space telescope, you can build many of them in different parts of the world, to overcome these limitations.
There are other reasons for going into space - atmospheric bluring, absorption and emission.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
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.
The practical viewing area is even smaller, because objects near the horizon are obscured by atmospheric effects...so there's plenty of advantage to being in space.
rj
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.
Actually, as far as Field of Regard goes (Field of view is a measure of how much you can see looking through the sensor...) there is very little difference between a telescope in Low Earth Orbit (LEO) and one on the Earth's surface. In both cases, the Earth blocks out about 2/3 of the viewable universe. Being 600 km above the surface of an object that is 12600 km in diameter doesn't help too much. However, Hubble of course moves through its orbit many times over one Earth day, so what its FOR changes pretty rapidy - this can be both good and bad... for instance if you are trying to take a very long exposure...
"It takes considerable knowledge just to realize the extent of your own ignorance." - Thomas Sowell
As another astronomer, I'll chime in that it's still apples and oranges. We couldn't build the LBT 15-20 years ago, and Hubble would be cheaper and better if we built it now. The points about the UV coverage of Hubble are especially good ones -- LBT will never work in the UV, and some science requires the UV. Furthermore, the results from the LBT will not be simply "10x" better resolution -- there is atmospheric effects to worry about and compensate for, and there is only a single baseline (to get 360 degree interferometry will require quite extended observations to get what astronomers call "coverage in the u-v plane).
Will the LBT kick astronomical ass? Almost certainly.
Will Hubble still be able to do things LBT can't? Yes, indeed.
Will the LBT be able to do things Hubble can't? Of course.
The Hubble cost-analysis is way more complex than these simple comparisons on slashdot always seem to apply. At this point, the appropriate questions are things like, is Hubble worth the cost of maintaining? Does it still provide a unique capability? What is the value of that unique capability? When can a bigger, better replacement fly? Etc.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
The Hubble sensitivity is not that enhanced from being in orbit (the atmosphere doesn't absorb all that much optical light at most wavelengths). Hubble also suffers from not being that big -- it's never going to be able to detect faint surface brightness objects (e.g., diffuse nebulosity, extended galaxies, etc., if it's too faint). You need BIG telescopes like LBT for that work.
There is, however, an area of faint astronomy where Hubble is unbeatable. And that is working on concentrated or point sources. Because Hubble can point, with high stability, for extended periods, you can detect objects that are currently impossible to observe from the ground. Check out www.stsci.edu and their press releases and look for the Hubble Deep Field images. They're spectacular, and LBT won't be able to touch them.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
Yes, there are things that Hubble can do that no other satellites can do, but not for the reasons you listed.
Hubble is one of multiple telescopes in NASA's Great Observatories project.
There are currently three space-bound observatories for astronomy.
For instance, Spitzer meets the qualifications you gave, the difference being that it operates in the IR range, while Chandra looks at x-rays.
Hubble works in the visible range. But that's not to say that it's the only space-based visible spectrum satellite, as there's also SOHO, which points at the sun, and isn't used to point anywhere but the sun.
[I'm not an astronomer, but I work on the STEREO and VSO projects]
Build it, and they will come^Hplain.
The number one thing that comes to my mind that hubble can do that the others can't is to focus on one object for more than a few hours. With the fine control that they have with the gyros, hubble can point at the same object for weeks at a time, which allows it to pick up much fainter objects, even if it doesn't have the resolution.
Estimates I have heard (and IANAA) have put the cost for further service missions at around have a billion dollars, which would be around 4 times the cost of building this telescope. And remember that mission will only keep the Hubble out for a limited time. Afterwards more missions will be required to keep it up longer. And money isn't the only problem. Currently our space program is relying on rather ancient shuttles to get to space. Recently the saftey of those shuttles has been called into question. Thus not only are we risking hundreds of millions of dollars for this science fair project, but also the lives of American astronauts.
Mathematics is made of 50 percent formulas, 50 percent proofs, and 50 percent imagination.
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.
Why on earth are environmentalists opposed to an observatory? I mean astronomers not only like clear air, they even think light is pollution!
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.
OK, I agree with you that the telescopes on Graham should be built, but your characterization of the opposition is wrong. There were two main reasons why the telescopes were opposed: 1) Mt. Graham is the home of the endangered red squirrel. 2) Mt. Graham is the sacred peak of the San Carlos Apache. The environmentalists were worried about the effects the increased activity would have on the squirrel (the University eventually made concessions on this issue), and the Apache opposed it because they have burial grounds on the mountain and consider it theirs.
"Short sightedness has led to massive wildfires that have burned more destructively than if the standard fire cycle were allowed to occur,"
Yeah, that's been going on in the West for the last 80 years. To pin it on the environmentalists is a bit unfair, as the policy of fire suppression predates the modern environmental movement by quite a bit. Most environmentalists I know support controlled burns as a solution; the (current) administration pushes clear cut logging as the solution. Result: impasse. Also, you can bet that Mt. Graham isn't going to see anything like the "standard fire cycle" now that there are millions of dollars invested in it.
"Personally I'd like it if there were another decent sized community within four hours drive of Phoenix that wasn't also in the desert"
How about Flagstaff, Sedona, Prescott, Jerome or Bisbee? Most of the state is within four hours of Phoenix.
For sure, that's why we've got the Spitzer space telescope (IR), the Compton X-Ray Observatory (X-rays, and gamma-rays too, I think) and a host of others, currently in orbit or in planning. Visible light penetrates our atmosphere quite nicely, and if AO pays off (as it seems poised to do), there's less need to put orbiting telescopes up there to view things in the visible.
The first AO systems were active by 1974 and used for astronomy (at the US Air Force Starfire range
in, umm, New Mexico) before 1980. See papers by
J Hardy et al.
-- Thus conscience does make cowards of us all - Hamlet