Massive Construction Effort Begins For World's Largest Telescope 74
An anonymous reader writes with this selection from a press release issued by the Harvard-Smithsonian Center for Astrophysics: "Astronomers have begun to blast 3 million cubic feet of rock from a mountaintop in the Chilean Andes to make room for what will be the world's largest telescope when completed near the end of the decade. The telescope will be located at the Carnegie Institution's Las Campanas Observatory-one of the world's premier astronomical sites, known for its pristine conditions and clear, dark skies. Over the next few months, more than 70 controlled blasts will break up the rock while leaving a solid bedrock foundation for the telescope and its precision scientific instruments."
It'll be the largest optical telescope, IF... (Score:4, Informative)
and only if, it's completed before the (larger) Thirty Meter Telescope [tmt.org] in Hawaii, and the (larger still) European Extremely Large Telescope [eso.org] in Chile.
And even if it is completed before TMT and E-ELT, as soon as either of them is completed, it'll lose the title.
Did I mention both TMT and E-ELT are also targeting completion by the end of the decade? Yup.
So, good luck, GMT!
(And it goes without saying that non-optical radio telescopes, which use dishes instead of mirrors, have long been much larger. And that even submillimeter telescopes, which also use dishes, are working on staying larger, with the 25-meter CCAT [ccatobservatory.org] planned for Chile later this decade.)
Re:Ground vs Space (Score:4, Informative)
With the advances in both active (compensation for deformation of the mirror due to gravity and it's position) and adaptive (compensation of the mirror to negate the effects of atmospheric distortion) optics ground based telescopes can come close to if not equal what can be done in space. When you couple the fact that you can build much larger apertures on the ground for significant less money than what is launched into space I wonder why they are still fooling around with space based telescopes.
Hubble has a 2.4M mirror and cost about 1.5B at launch and over it's lifetime a total of about 6B when you figure in all of the shuttle trips for maintenance and the ground support costs. The 10M Keck telescopes cost 94M each when they were built. The James Webb telescope has become a CF of huge proportions with an estimated cost of close to 8.8B through 2018.
Don't get me totally wrong here. Some magnificent discoveries were made with Hubble along with Swift and Chandra. We do need some space based telescopes but the cost of space base instruments is enormous compared to ground based and there are significant advancements that are being made with sensors and other ground base instruments that are pushing the need for space base instruments further out of the picture.
Re:Why not on Nullarbor Plain? (Score:5, Informative)
Re:It'll be the largest optical telescope, IF... (Score:5, Informative)
Yep, of course. In fact, the telescope I run at my job had "the largest monolithic mirror ever made" from 1999 until 2004 (when Roger Angel started cranking out 8.4-meter ones). Wasn't considered the largest telescope, of course, because segmented 10-meter mirrors of the Keck twins (1992 and 1996) next door to it were larger overall, just segmented.
That said, using the phrase "world's largest" in the headline before the first concrete pour invites comments like mine. ;)
Re:Where is Greenpeace? (Score:4, Informative)
Extended and ongoing environmental impact studies are part and parcel of the final process of choosing a telescope site these days. We do try to be very careful to be considerate when building these facilities & work with teams of local environmental biologists. Also, in most cases nowadays, one of the preconditions for site use is that the site is returned to its original pristine state once the telescope in finally removed again.
There is, however, sometimes still local opposition. E.g. in Hawaii, this is usually on native cultural grounds, & nowadays, an effort is made to involve local native cultural leaders (in the early days, some culturally insensitive decisions were made, and both sides of the debate are aware of this).
In the case of Chile, such facilities are often welcomed, as they're much less damaging than the extensive mining operations already in existence there, but still provide good engineering and other technical jobs for Chileans. Plus, many Chileans are proud that their country can boast some of the finest such research facilities in the world.
(Full disclosure: I am both a professional observatory staff astronomer and a longtime member of Greenpeace).