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World's Largest Telescope Begins Production
JohnnyNapalm writes "The Aggie Daily News is reporting today that the first mirrors have been cast for the world's largest telescope. The result of cooperation from some of the foremost institutions in education and science in the nation, the Giant Magellan Telescope stands to operate at a resolution 10 times larger than the Hubble. The project, set to be constructed in Chile, is slated for completion in 2016."
Am I alone in feeling that we haven't even used hubble to the fullest extent of its abilities? Not sure why this is a priority right now.
If this is going to beat it out the lenses will have to be tremendous. It was considered a feat of engineering manufacturing and shipping the VLT's lenses
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Unfortunately adaptive optics doesn't help with frequencies that are blocked by the opaque (at those frequencies) atmosphere.
As far as I can tell this telescope does not use adaptive optics. Why not? Because the mirror is so enormous, I guess. Isn't there a method to use materials with variable refractive properties that can be placed on top of the mirror?
However, put that same sophisticated, adaptive telescope in space, and I'd be willing to bet you'd see yet further improvement. Besides which, even a composite telescope is going to be limited in size, due to the fact that you can't correct all of the errors - the machinary won't be capable of altering the positions of the mirrors accurately enough, or measuring their positions for computational correction.
In space, you should be able to build much larger composite mirrors, as you should be able to place things much more accurately. If the mirrors are made in space, then that would be even better, as there wouldn't be so many flaws that would need correcting.
Instead of building one super-giant telescope, they might be better building two or three slightly smaller giant telescopes, then hooking them up as an interferometry array. The reason being that you'll get diminishing returns on how much light you can get in anyway, an array allows you to obtain greater accuracy and you can use the array as multiple single telescopes if there is nothing requiring the extra detail.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
I had the wonderful experience of being an undergraduate in astrophysics at UC Santa Cruz, where a grant in adaptive optics was paving the way for ground-based telescopes. By shining a laser straight where the telescope is pointed, aberrations and distortions from the atmosphere can be measured and exactly countered by the telescope, effectively cancelling atmospheric effects to a remarkable degree. Check out http://cfao.ucolick.org./ The main telescope was outside of San Jose, CA, which might seem a strange location for a telescope due to its proximity to a large city. But since all of the streetlamps in San Jose are sodium (whose spectral properties are well known and simple), those features can be subtracted from any measured spectra and in conjunction with adaptive optics, the telescope outside northern california's largest city produces world-class astronomy. This telescope being built should be pretty neat. I wonder how they will deal with gravitational aberrations. Plus scientists won't ever need to face the threat of government letting their instrument "deorbit" while still producing good data.
NASA's purse a bit LIGHT? I can't think of many non-military organisations which have bigger budgets. Compared to the results they produce, NASA get astronomical amounts of money, no pun intended. Where does it all go?
We need a proper space age with proper engineers to build giant telescopes in space. None of this 'let's spend hundreds of billions on a badly-designed space shuttle then keep it on the ground because a spec of paint is out of place.'
Get some proper reliable, efficient launch systems, then get some telescope-building facilities in outer space, and build a 200m telescope, no flaws, no imperfections, and we can do some proper observing. With the money and technology available we should be able to see into the future by now, not a few low-detail pictures of nearby nebulae.
There is already a Magellan project, a 2 telescope optical interferometer
Grandparent has a point though. This naming convention is a poor choice. What will they call the next one? "OMG The Really REALLY Big Ginormous Magellan Telescope"? And the one after that?
Marketroids (and apparently the ivory tower residents responsible for naming telescopes) need to learn from the debacle of USB Hi-Speed vs Full-Speed. Future-proof the meaning of your technology's name by assigning it based on absolute, and NOT relative, criteria. "Giant" has no real meaning. "25.6m" (the resolving power of the GMT) does have a meaning that will persist into the future.
1) Absorption. The atmosphere absorbs in many wavelengths of interest, including the UV and parts of the IR. There are some projects that can never be done on the ground.
2) Background emission. The atmosphere "glows" at a number of wavelengths; this acts as a source of background contamination and reduces your sensitivity.
3) Blurring. The stars twinkle. This reduces the sharpness of ground-based images by an enormous factor (for GMT in the optical, excluding AO, by a factor of about 200).
People keep mentioning "adaptive optics" as a way to overcome the blurring from the atmosphere. But the harsh truth is that AO doesn't work all that well, for situations where you actually need to get rid of the effects of the atmosphere. Sure, it sharpens up pictures of binary stars pretty well, but it leaves a bunch of uncalibrated "scruff" near the star that e.g. makes it impossible to look for planets near that star. Another limitation of AO is that it requires a bright star to guide on - although lasers are becoming available. Mind you, the laser stuff seems to have even worse issues with calibration. Finally, AO has a very limited effective field of view; you can only correct over a small patch at a time. It makes it hard to do wide-field surveys that way.
Sooo, the upshot is that you need both, and will continue to need bothy for a long time. That being said, I wish the GMT guys lots of luck.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?