Thirty Meter Telescope

The Thirty Meter Telescope (TMT) is a planned extremely large telescope (ELT) that has become controversial due to its location on Mauna Kea, on the island of Hawaiʻi. The TMT would become the largest visible-light telescope on Mauna Kea. 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 (65') in diameter, using either small segments that create one large mirror, or a grouping of larger 8-meter (26') mirrors working as one unit. The US National Academy of Sciences recommended a 30-meter (100') telescope be the focus of U.S. interests, seeking to see it built within the decade. Scientists at the University of California, Santa Cruz and Caltech began development of a design that would eventually become the TMT, consisting of a 492-segment primary mirror with nine times the power of the Keck Observatory. Due to its light-gathering power and the optimal observing conditions which exist atop Mauna Kea, the TMT would enable astronomers to conduct research which is infeasible 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 nations. Demonstrations attracted press coverage after October 2014, when construction was temporarily halted due to a blockade of the roadway. When construction of the telescope was set to resume, construction was blocked by further protests each time. In 2015, Governor David Ige announced several changes to the management of Mauna Kea, including a requirement that the TMT's site will be the last new site on Mauna Kea to be developed for a telescope. The Board of Land and Natural Resources approved the TMT project, but the Supreme Court of Hawaii invalidated the building permits in December 2015, ruling that the board had not followed due process.