The Thirty-Meter Telescope, a leader in the new generation of mammoth telescopes, finally has a home: Mauna Kea, Hawaii (press release). To host the billion dollar project and what would be the largest telescope in the world, the Aloha State beat out its competitor, the remote peak of Cerro Armazones in Chile, based largely on Mauna Kea’s “atmospheric conditions, low average temperatures, and low humidity,” chair of the TMT board of directors Henry Yang announced 21 July.
On the northern slope of Mauna Kea, the TMT will join an impressive gathering of other sky-peepers, including the soon-to-be-dwarfed Keck telescopes which, with primary mirrors some 10-m in diameter, had been amongst the world’s largest optical and infrared telescopes. While the Keck mirrors are assemblages of 36 six-sided mirrors measuring 1.8 m across, the TMT’s will be comprised of 492 1.44-m mirrors — giving it nine times the light-gathering capacity.
The TMT will also be the first telescope ever with “adaptive optics” built in from the beginning, a technique that senses corrects for atmospheric turbulence, giving the telescope “spatial resolution more than 12 times sharper than what is achieved by the Hubble Space Telescope”. The TMT will use all of this hardware to “detect and study light from the earliest stars and galaxies, analyze the formation of planets around nearby stars, and test many of the fundamental laws of physics", says the press release.
The “consensus decision” to build on Mauna Kea has been two years in the making, says Yang, though “they’re both lovely sites” and “the people of both places are wonderful”. But scientifically-speaking, Mauna Kea had more going for it: it’s higher (by 3000 feet), drier (an important quality for infrared measurements), has less atmospheric turbulence, and its average temperature fluctuates less throughout the year and over a day, notes TMT board member Richard Ellis.
The main argument against Hawaii was cultural. The Mauna Kea summit is sacred to indigenous groups on the island, while Cerro Armazones has no known historical or cultural significance. A giant new telescope means many years of cranes, trucks, noise and pollution, giving the TMT team a few tough hurdles to cross — completing an Environmental Impact Statement and getting a Conservation District Use Permit approved by the state.
But Yang is optimistic, as the Hawaiian government already approved the TMT land use management plan. “We’ve devoted several years to understanding the environmental, cultural, and legal issues unique to Mauna Kea,” he says. “We’re confident that we made the right decision at this time.”
On-site construction for the TMT is scheduled to begin in 2011 and end in 2018, says Yang. If all goes as planned, TMT will be the largest telescope in the world. But this designation might not last for long — hot on the TMT’s heels (for now) is the European Southern Observatory’s own giant mirror with an equally clever name, the European Extremely Large Telescope, slated to be 42 meters in diameter. And down the road from TMT’s headquarters in Pasadena is the command center of its hometown rival: the Giant Magellan Telescope, a planned 7-mirrored scope with the collecting area equivalent to 21.4 m.