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The Thirty Meter Telescope (TMT) is an astronomical observatory with an Extremely Large Telescope (ELT) that has become the source of controversy over its planned location on Mauna Kea in the state of Hawaii. Scientists have been considering ELTs since the mid 1980s. In 2000, astronomers considered the possibility of a telescope with a light-gathering mirror larger than 20 meters in diameter. The technology to build a mirror larger than 8.4 meters does not exist; instead scientists considered using either small segments that create one large mirror, or a grouping of larger 8-meter mirrors working as one unit. The US National Academy of Sciences recommended a 30-meter telescope be the focus of U.S. interests, seeking to see it built within the decade. Scientists at the University of California and Caltech began development of a design that would eventually become the TMT, consisting of 492 segmented mirrors with nine times the power of the Keck telescope. Due to its immense light-gathering power and the optimal observing conditions which exist atop Mauna Kea, the TMT would enable astronomers to conduct research which is unfeasible with current instruments. The TMT is designed for near-ultraviolet to mid-infrared (0.31 to 28 μm wavelengths) observations, featuring adaptive optics to assist in correcting image blur. The TMT will be at the highest altitude of all the proposed ELTs. The telescope has government-level support from several R&D spending nations: China, Japan, Canada and India. Construction of the TMT on land which is sacred to native Hawaiians, attracted international coverage after October 2014, when construction was temporarily halted voluntarily due to protests. While construction of the telescope was set to resume on April 2 and later on June 24, 2015, it was blocked by further protests each time.〔 The observatory and telescope are expected to be operational on Mauna Kea by 2024.〔 ==History== In 2000, astronomers began considering the potential of telescopes larger than 20 meters in diameter. Two technologies were considered; segmented mirrors like that of the Keck Observatory and the use of a group of 8-meter mirrors mounted to form a single unit. The US National Academy of Sciences made a suggestion that a 30-meter telescope should be the focus of US astronomy interests and recommended it to be built within the decade. The University of California, along with Caltech began development of a 30-meter telescope that same year. The California Extremely Large Telescope (CELT) began development along with the Giant Magellan Telescope, the Giant Segmented Mirror Telescope (GSMT) and the Very Large Optical Telescope (VLOT). These studies would eventually become the Thirty Meter Telescope. The TMT would have nine times the collecting area of the older Keck telescope using slightly smaller mirror segments in a vastly larger group.〔 Another telescope of a large diameter in the works is the European Extremely Large Telescope (E-ELT) being built in northern Chile. The telescope is designed for observations from near-ultraviolet to mid-infrared (0.31 to 28 μm wavelengths). In addition, its adaptive optics system will help correct for image blur caused by the atmosphere of the Earth, helping it to reach the potential of such a large mirror. Among existing and planned ELTs, the TMT will have the highest altitude and will be the second-largest telescope once the E-ELT is built. Both use segments of small 1.44 m hexagonal mirrors—a design vastly different from the large mirrors of the Large Binocular Telescope (LBT) or the Giant Magellan Telescope (GMT). The TMT has government-level support from two large R&D spending nations; China and Japan, as well as other top R&D ones, including Canada and India. The United States is also contributing some funding, but less than the formal partnership. The telescope was given approval by the state Board of Land and Natural Resources in April 2013. The Intermediate Court of Appeals of the State of Hawaii declined to hear an appeal of the permit until the Hawaii Department of Land and Natural Resources first issued a decision from a contested case hearing that could then be appealed to the court. The dedication and ground-breaking ceremony was held, but interrupted by native Hawaiian protesters on October 7, 2014. The project has now become the focal point of escalating political conflict, police arrests, and continuing litigation due to concerns over proper use of conservation lands, continued environmental degradation and the process of environmental and cultural impact review, the status of the Hawaii ceded land trust, native Hawaiian cultural practice and religious rights, and concerns over the lack of meaningful and inclusive dialogue during the permitting process. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thirty Meter Telescope」の詳細全文を読む スポンサード リンク
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