Slashdot Mirror
Construction of World's Largest Optical Telescope Approved
The University of Hawaii at Hilo has been granted a permit by the Hawaii Board of Land and Natural Resources to begin construction of the $1.3 billion Thirty Meter Telescope (TMT). From the article: "The TMT has been in development for over a decade, but the large amount of land needed for its construction raised concerns over the environmental and cultural impact of such a project. Now, however, the land board has rendered a final decision, saying that the university had satisfied the eight criteria necessary under Hawaiian state law to allow the venture to go forward. The giant TMT will be an optical and infrared telescope with enough coverage area and sharpness to observe light from 13 billion years ago, track extrasolar planets, and observe planets and stars in their early formative years."
I would be very interested to know how the mirror is constructed because it must be an engineering marvel.
Acording to Wikipedia:
This mirror will be segmented and consist of 492 smaller (1.4 m), individual hexagonal mirrors. The shape of each segment, as well as its position relative to neighboring segments, will be controlled actively.
Actually, strictly speaking you could almost buy two. The average cost per unit of $2.1 billion is mostly born by one time, already sunk development costs, the flyaway cost is a "mere" $0.7 billion.
The reason they're so damn expensive is that the Cold War ended when they were almost finished and most of the money had been spent, meaning instead of building hundreds of the things, they only built 21. A weapon like the B2 is only needed against a well armed and geographically huge opponent, such as the Russia, China or the United States itself, none of which America has the pressing need to bomb in the near future. So they just built a few, made them public as some sort of national prestige stunt for scaring "rogue states" with the threat that a heavy bomber could be flying over their territory without anyone knowing, rather than building en masse to become a credible attack force towards large powers as they were intended.
In contrast fhe F-22 project cost 66 Billion compared to the B-2's 44 Billion, the difference is, they built hundreds of those, so the cost looks lower.
When Argumentum ad Hominem falls short, try Argumentum ad Matrem
NASA has that covered: the James Web Space Telescope will be at the Earth-Sun L2 point. It is much smaller than 30 meters though: its mirror is 6.5 meters.
You'll also notice that the Webb telescope costs a lot more than the 30-meter telescope, which is another part of the answer to your question. There is enough going on in astronomy today that we need more than one really good telescope. It makes sense to build the multiple telescopes with different properties so they're specialized for different science.
[Sir Garlon] is the marvellest knight that is now living, for he destroyeth many good knights, for he goeth invisible.
Because it will have a lot more optical clarity than Hubble. There's a distinct limit to the aperature acheivable with space launch. Hubble's beyond it; the shuttle is retired. While space is great for optical bands that are absorbed by the atmosphere, it's worse for *EVERYTHING* else. It costs more, it's slower to design, it's harder to fix, it has hard aperature and focal length limitations, it has bandwidth caps, it has vibration problems, it has thermal stability problems, it has power limitations, it has pointing challenges, it has shit flying into it at speeds that would be hypersonic in the atmosphere, it has radiation problems, and it has "science fair project" political problems.