Slashdot Mirror
Powerful Optical Telescope Captures First Binocular Images
The Large Binocular Telescope consists of two 8.4-meter mirrors which function in tandem to provide resolution greater than that of the Hubble Telescope. The LBT's first "binocular" images were captured recently, marking the end to a long and laborious construction process. We previously discussed the LBT when images were captured from the first mirror to be installed. Quoting:
"The LBT ... will combine light to produce the image sharpness equivalent to a single 22.8-meter (75-foot) telescope. 'To have a fully functioning binocular telescope is not only a time for celebration here at LBT, but also for the entire astronomy community,' UA Steward Observatory Director, Regents' Professor and LBT Corp. President Peter A. Strittmatter said. 'The images that this telescope will produce will be like none seen before. The power and clarity of this machine is in a class of its own. It will provide unmatched ability to peer into history, seeing the birth of the universe.'"
Something like that already exists.
Everything will seen through an infinity-symbol-shaped viewing area.
And, you know, It Must Have Been A Beautiful Baby, Cause Baby, Look At It Now...
I'd be happy with a binocoular telescope that had pair of 15 cm objective mirrors and they get a pair of 840 cm mirrors.
Apocalypse Cancelled, Sorry, No Ticket Refunds
No hot chick changing clothes in her room will be safe now ...
If two telescopes are good, wouldn't three be even better?
It's not like two is some arbitrary limit... right?
[Fuck Beta]
o0t!
I go to school there and surprisingly enough the building that holds it is relatively small in comparison to other telescopes. I dono how they do it!
BSD is for people who love Unix, Linux is for people who hate Microsoft.
A high-quality binocular telescope starts work just when the next generation of 3D movie effects is rolled out. Am I the only one who's glad to live near a place that shows IMAX?
I've calculated my velocity with such exquisite precision that I have no idea where I am.
I would have named it the Binocular Large Telescope.
If you look through the other end, do things look really, REALLY small?
Have gnu, will travel.
In 2015 the European Space Agency is planning to launch Darwin. 4 spacecraft. 3 light collectors (based on the Herschel design) and one hub where the light is collected. If it works out (the telescopes and the hub must stay in formation with millimetre precision), we'll have a space telescope with an effective mirror size of several hundred meters.
The objective is the study of extrasolar planets, and the telescope will record in IR for purposes of recording signs of life.
Multiple mirror telescopes in space are probably the only way we will get to the point where we'll have close up pictures of extrasolar planets the size of earth.
And we're getting there.
I'm a dreamer, the world is my playpen. But hey, I'm a serious person, I can't dream all the time.
The ground-based telescopes are getting ever larger and more powerful. Atmospheric disturbance effects are nullified easily now. Are there any space telescope types that won't be obviated by these advancements?
Bearded Dragon
Meh... you can do that with the naked eye from the same distance.
Earth based telescopes are still limited by clear nights without cloud cover. Space based telescopes don't have this restriction. Also earth based telescopes are limited to the times of the day the sun is not up. ;)
Isn't there a way to make a "holographic sensor" into which light from a telescope could be directed, which would give the same increase in visual completeness that holograms give over stereographic imagery?
--
make install -not war
A giant View-Master
What?
Serious question: is the light that can be collected a few hundred meters away better or even different from the light that can be collected close to each other? In other words, is a group of small mirrors with the same surface area as a single large mirror inherently better? Or is this simply a matter of launcher-logistics (i.e. maximum launchable mirror size)?
;-) But not on the optics, and I'm not an astronomer...
BTW, I did a lot of work on the Herschel spacecraft
It's almost the same with microprocessors. Are the multi core better than a very quick single core (e.g. 2x2Ghz vs 4 Ghz)?
In the case of telescopes how big can you make a mirror without imperfections and tolerant to temperature changes? And then are coming the logistic problems.
For multiple telescopes you can enhance the image, compensate for defects in individual mirrors or atmospheric distortions but in absolute terms you'll obtain a better image from a single telescope with the equivalent mirror surface. There are other problems as well but these are the first coming in mind.
If you compare this NGC2770 image with the one taken by SDSS (Google Earth), one star is clearly missing on the SDSS image (the brightest one). That would certainly explain the choice of the target but there is no mention on the linked article. Anyway, I expected a larger difference in resolution between the image taken by a 2.5m wide-angle telescope (SDSS) and a 2x8.4m binocular telescope.
I visited the LBT last fall and it seemed pretty large to me. The base of the building is about 5 stories high and the top part that houses the telescope and rotates is 10 stories high. It's a great tour.
It's not "better", it's "just as good" while being vastly, vastly cheaper. Also, it's not the surface area itself that matters for resolution. So several small mirrors (with a smaller surface area), spaced apart, can deliver the same resolution as one huge mirror.
Not true, I'm afraid: Darwin was not picked by ESA as one of the missions to be studied for the so-called L (large) slot for launch in 2017-2018 during the recent Cosmic Vision selection exercise. Large missions in the running for that slot are XEUS (large X-ray telescope), LISA (gravitational wave observatory), and TANDEM/LAPLACE (missions to the outer planets, Titan and Jupiter, respectively, only one of which would happen). All of these would be collaborations with other space agencies.
It was felt that the precision formation-flying and interferometric beam combination techniques needed to make Darwin work were not mature enough for implementation yet. The science it's aiming at is of very great importance and such a project will undoubtedly return for consideration in future rounds of Cosmic Vision, but I'd say there's little chance of something like Darwin flying prior to 2022-2025.
In passing, you're right that Darwin would have the angular resolution of telescope several hundred metres in diameter, but it wouldn't have the collecting area of such a telescope. For direct detection of terrestrial-mass exoplanets close to their bright parent stars, that's fine; for other science such as studying galaxies forming just after the Big Bang, a larger collecting area would also be required. Comparison of the parts of parameter space covered by projects as disparate as Darwin, LBT, JWST, and future ELTs (ground-based extremely large telescopes, diameters and collecting areas of 30-40m diameter, under development for 2015-2020) is non-trivial.
This was my question when I read the FA. Like another respondent, I thought that with the stars so far away there wouldn't even be any parallax. I decided to ask my friend Google what are the advantages of a binocular telescope and found this...
"So what does it feel like to actually use a large aperture binocular telescope? David gives us his account; Mind blowing is probably the phrase that springs to mind..."
"The incredible sense of total immersion in the reality of the experience is what binoculars are all about. It's astronomy at another level. Seeing the large globular cluster Omega Centauri for the first time almost made me fall backwards off the step. The depth and resolving power on this object is spellbinding. Moving just outside the field of view of this object and panning slowly towards it, you're firstly presented with a pitch black sky with a scattering of random stars. As you move onto the object your eyes and senses are completely overwhelmed. You can look deeper and deeper inside this cluster and there is always more to see. It feels as though I've arrived on the doorstep to this cluster in my spaceship."
"A definite three-dimensional feeling is present, the objects appear to float almost in front of you, even though this is obviously not possible due to the enormous distance of these objects. One explanation is an effect called chromatic stereopsis, which due to chromatic aberrations in your eyes makes the red and blue stars focus at slightly different distances. Simple things, like double stars that have never captured my imagination are suddenly transformed into objects worth gazing at. Smaller and much fainter globular clusters all benefited from the relaxing view using two eyes. The fainter globular clusters if viewed with only one eye, needed averted version to make them visible, however with both eyes open, they were blatantly obvious."
This amateur astronomer with a binocular 16" telescope concludes after 6 months of constant use: "So far I have not found any category of object to observe that does not benefit greatly from the advantages of a true binocular telescope."
As an amateur astronomer I can say that what you wrote is absolutely true. It's something very different and wonderful to be able to observe with both your eyes even if the image they are getting is completely the same. Still, it has nothing to do with why people build large binocular observatories such as this. One reason is that it is probably cheaper to build two 8.4m mirrors that won't distort under their weight then one large mirror of the same surface area. The other is the resolution gain that is possible with the binocular setup through interferometry.
The other is the resolution gain that is possible with the binocular setup through interferometry.
Could you please elaborate on that? I found one of the original research papers that led to this telescope, and it said something like "the advantages of a binocular telescope to interferometry are well known" - not very helpful to us non-astronomers.
I am no expert, but as I understand it, the total amount of light collected is only a factor in increasing the power of the telescope. So, two telescopes of a certain size would collect the same amount of light however fare apart they were. However, when the light is combined they can use interferometry principles to obtain a higher resolution image than would be otherwise be possible from the same location (and no, the kind of distance apart that they are would not provide meaningful parallax info at stellar distances). So, having them further apart will increase the resolving power of the telescope. Basically, the distant stars and galaxies will look just as bright, but it's the difference between seeing a bright spec, blurred by maladjusted lenses, compared to a sharp image, with lots of detail given by well focused lenses. Total surface area provides brightness. Spacing provides detail and resolution. At least this is how I understand it. Those more knowledgeable will be able to answer better.
I like my dinosaurs feathery, and my pterosaurs hairy (or is it pycnofibery?)
Here is a nice explanation: http://en.wikipedia.org/wiki/Astronomical_interferometer
I would have modded you up, but I also want to comment.
You're no doubt right that it's extremely difficult make a space telescope like Darwin a reality. But I still think that they should give it very high priority to make it happen. There's little you can do in science or space engineering that has more potential than this. Just imagine what an impact it would have, if we found a planet 15 or 20 light years away, that showed every sign of being teeming with abundant life. Just like Earth.
It would inspire school children, politicians, Hollywood and everybody else enormously, I think. People would demand an interstellar space probe sent out. Even knowing that it would take a century or more, before the probe could begin to send back pictures. NASA would have to develop some super ion engine or something, with interstellar capabilities. They would have something really inspiring to do again.
I don't know why authors don't point to original sources instead of news sites.
http://medusa.as.arizona.edu/lbto
has links to the press release, but a lot of other stuff as well, including why it was built at:
http://medusa.as.arizona.edu/lbto/why.htm
and information about the telescope, including photos, at:
http://medusa.as.arizona.edu/lbto/telescope.htm
The 'why it was built' article could have answered the speculation in many of the above posts.
What you do with a computer does not constitute the whole of computing.
Resolution increases linearly with aperture. The effective aperture for the LBT would then be the separation of the two telescopes plus twice the aperture (8.4 m) of either. You only get that increased resolution directly along only one axis--the one through both telescopes. So you take multiple images and do some math, and in many cases you should be able to arrive at the max resolution--which is equivalent to a single instrument of 22.8 m aperture.
See my post above, open the 'why build' link in another tab, and scroll down to the simulated infrared images of Io. Now see
http://www.keckobservatory.org/article.php?id=54
which is another image of Io in infrared, from Keck, which is a very large, highly-capable system, at one of the best sites in the world. If the LBT reality is as good as the simulations--wow.
BTW, the light-gathering power varies as the square of aperture. So this pair of 8.4 m mirrors gives you the equivalent of a single 11.8 m instrument. So as a light-bucket, it's quite as much of a win as it is in resolution. But 11.8 m is still huge. The Keck telescopes are 10 m., for instance, and astronomers were stoked about them coming on line.
This stuff knocks me out. I remember seeing images of the Jovian moons in which you barely tell Io was a bit off-white.
What you do with a computer does not constitute the whole of computing.
Serious question: is the light that can be collected a few hundred meters away better or even different from the light that can be collected close to each other? In other words, is a group of small mirrors with the same surface area as a single large mirror inherently better?
There are two main factors determining the power of a telescope mirror.
1) Collecting area. A bigger mirror will collect more light and allow you to see fainter objects. A group of small mirrors will have a collecting area more or less equivalent to a single mirror with the same total area.
2) Resolving power, that is, the ability of detecting very small details. For diffractive optics reasons, this is proportional to the diameter of the mirror. If you have a group of telescopes, it is instead proportional to the distance between them, and if you can space them say 100 meters apart it's potentially *much* better. Such a system is called an interferometer
Combining light in interferometric mode from two or more telescopes is difficult. For example, you have to know the exact distance between them within a small fraction of the wavelength you are observing. For optical or infrared observation, that means a small fraction of a micron. On the LBT, it is easier than usual because the two mirror are mounted on the same supporting structure. Radio interferometers are common because they work with millimeter and centimeter wavelengths, and beam combining is relatively easy.
Another problem is that an interferometer will "see" an image only along a single direction - it will detect changes in illumination (corresponding to the features in the image: borders, points, etc.) only if they are perpendicular to the line connecting the two mirrors. If you want a more or less complete image, you have to rotate the telescope with respect to the sky, or use many telescopes so that you have many different directions to play with.
Hope this helps.
What kind of resolution would something like that have if it was in orbit... pointed at us?