Thirty Meter Telescope

In 2000, astronomers began considering the potential of telescopes larger than in diameter. The technology to build a mirror larger than does not exist; instead scientists considered two methods: either segmented smaller mirrors as used in the Keck Observatory, or a group of 8-meter (26') mirrors mounted to form a single unit. The US National Academy of Sciences made a suggestion that a telescope should be the focus of US astronomy interests and recommended that it 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 Segmented Mirror Telescope (GSMT), and the Very Large Optical Telescope (VLOT). These studies would eventually define 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. Each night, the TMT would collect 90 terabytes of data. The TMT has government-level support from the following countries: Canada, Japan and India. The United States is also contributing some funding, but less than the formal partnership. Proposed locations In cooperation with AURA, the TMT project completed a multi-year evaluation of six sites: • Roque de los Muchachos Observatory, La Palma, Canary Islands, Spain • Cerro Armazones, Antofagasta Region, Republic of Chile • Cerro Tolanchar, Antofagasta Region, Republic of Chile • Cerro Tolar, Antofagasta Region, Republic of Chile • Mauna Kea, Hawaii, United States (This site was chosen and approval was granted in April 2013) • San Pedro Mártir, Baja California, Mexico • Hanle, Ladakh, India The TMT Observatory Corporation board of directors narrowed the list to two sites, one in each hemisphere, for further consideration: Cerro Armazones in Chile's Atacama Desert and Mauna Kea on Hawaii Island. On July 21, 2009, the TMT board announced Mauna Kea as the preferred site. The final TMT site selection decision was based on a combination of scientific, financial, and political criteria. Chile is also where the European Southern Observatory is building the ELT. If both next-generation telescopes were in the same hemisphere, there would be many astronomical objects that neither could observe. The telescope was given approval by the state Board of Land and Natural Resources in April 2013. based on potential disruption to the fragile alpine environment of Mauna Kea due to construction, traffic, and noise, which is a concern for the habitat of several species, and because Mauna Kea is a sacred site for the Native Hawaiian culture. The Hawaii Board of Land and Natural Resources conditionally approved the Mauna Kea site for the TMT in February 2011. The approval has been challenged; however, the Board officially approved the site following a hearing on February 12, 2013. Partnerships and funding The Gordon and Betty Moore Foundation has committed US$200 million for construction. Caltech and the University of California have committed an additional US$50 million each. Japan, which has its own large telescope at Mauna Kea, the Subaru, is also a partner. In 2008, the National Astronomical Observatory of Japan (NAOJ) joined TMT as a collaborator institution. The following year, the telescope cost was estimated to be $970 million to $1.4 billion. That same year, the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) joined TMT as an observer. The observer status is the first step in becoming a full partner in the construction of the TMT and participating in the engineering development and scientific use of the observatory. By 2024, China was not a partner in TMT. In 2010, a consortium of Indian Astronomy Research Institutes (IIA, IUCAA and ARIES) joined TMT as an observer, subject to approval of funding from the Indian government. Two years later, India and China became partners with representatives on the TMT board. Both countries agreed to share the telescope construction costs, expected to top $1 billion. India became a full member of the TMT consortium in 2014. In 2019 the India-based company Larsen & Toubro (L&T) were awarded the contract to build the segment support assembly (SSA), which "are complex optomechanical sub-assemblies on which each hexagonal mirror of the 30-metre primary mirror, the heart of the telescope, is mounted". The continued financial commitment from the Canadian government had been in doubt due to economic pressures. In April 2015, Prime Minister Stephen Harper announced that Canada would commit $243.5 million over a period of 10 years. The telescope's unique enclosure was designed by Dynamic Structures Ltd. in British Columbia. In a 2019 online petition, a group of Canadian academics called on succeeding Canadian Prime Minister Justin Trudeau together with Industry Minister Navdeep Bains and Science Minister Kirsty Duncan to divest Canadian funding from the project. , the Canadian astronomy community has named TMT its top facility priority for the decade ahead. ==Design==

The TMT would be housed in a general-purpose observatory capable of investigating a broad range of astrophysical problems. The total diameter of the dome will be with the total dome height at (comparable in height to an eighteen-storey building). The total area of the structure is projected to be within a complex. Telescope The centerpiece of the TMT Observatory is to be a Ritchey-Chrétien telescope with a diameter primary mirror. This mirror is to be segmented and consist of 492 smaller (), individual hexagonal mirrors. The shape of each segment, as well as its position relative to neighboring segments, will be controlled actively. A secondary mirror is to produce an unobstructed field-of-view of 20 arcminutes in diameter with a focal ratio of 15. A flat tertiary mirror is to direct the light path to science instruments mounted on large Nasmyth platforms. The telescope is to have an alt-azimuth mount. Target acquisition and system configuration capabilities need to be achieved within 5 minutes, or ten minutes if relocating to a newer device. To achieve these time limitations the TMT will use a software architecture linked by a service based communications system. The moving mass of the telescope, optics, and instruments will be about . The design of the facility descends from the Keck Observatory. This system will produce diffraction-limited images over a 30-arc-second diameter field-of-view, which means that the core of the point spread function will have a size of 0.015 arc-second at a wavelength of 2.2 micrometers, almost ten times better than the Hubble Space Telescope. Scientific instrumentation Early-light capabilities Three instruments are planned to be available for scientific observations: • Wide Field Optical Spectrometer (WFOS) provides a seeing limit that goes down to the ultraviolet with optical (0.3–1.0 μm wavelength) imaging and spectroscopy capable of 40-square arc-minute field-of-view. The TMT will use precision cut focal plane masks and enable long-slit observations of individual objects as well as short-slit observations of hundreds of different objects at the same time. The spectrometer will use natural (uncorrected) seeing images. • Infrared Imaging Spectrometer (IRIS) mounted on the observatory MCAO system, capable of diffraction-limited imaging and integral-field spectroscopy at near-infrared wavelengths (0.8–2.5 μm). Principal investigators are James Larkin of UCLA and Anna Moore of Caltech. Project scientist is Shelley Wright of UC San Diego. • Infrared Multi-object Spectrometer (IRMS) allowing close to diffraction-limited imaging and slit spectroscopy over a 2 arc-minute diameter field-of-view at near-infrared wavelengths (0.8–2.5 μm). ==Approval process and protests==

Joshua Lanakila Mangauil, along with Kahoʻokahi Kanuha and Hawaiian sovereignty supporters block the access road to Mauna Kea in October 2014, demonstrating against the building of the Thirty Meter Telescope. In 2008, the TMT corporation selected two semi-finalists for further study, Mauna Kea and Cerro Amazones. In July 2009, Mauna Kea was selected. Mauna Kea is ranked as one of the best sites on Earth for telescope viewing and is home to 13 other telescopes built at the summit of the mountain, within the Mauna Kea Observatories grounds. Telescopes generate money for the big island, with millions of dollars in jobs and subsidies gained by the state. Mauna Kea is the most sacred mountain in Hawaiian culture as well as conservation land held in trust by the state of Hawaii. The BLNR held hearings on December 2 and December 3, 2010, on the application for a permit. On February 25, 2011, the board granted the permits after multiple public hearings. 2014-2015: First blockade, construction halts, State Supreme Court invalidates permit The dedication and ground-breaking ceremony was held, but interrupted by protesters on October 7, 2014. The project became the focal point of escalating political conflict, police arrests and continued litigation over the proper use of conservation lands. Native Hawaiian cultural practice and religious rights became central to the opposition, with concerns over the lack of meaningful dialogue during the permitting process. In late March 2015, demonstrators again halted the construction crews. On April 2, 2015, about 300 protesters gathered on Mauna Kea, some of them trying to block the access road to the summit; 23 arrests were made. Once the access road to the summit was cleared by the police, about 40 to 50 protesters began following the heavily laden and slow-moving construction trucks to the summit construction site. viewed the development as positive but said opposition to the project would continue. On April 8, 2015, Governor Ige announced that the project was being temporarily postponed until at least April 20, 2015. Construction was set to begin again on June 24, though hundreds of protesters gathered on that day, blocking access to the construction site for the TMT. Some protesters camped on the access road to the site, while others rolled large rocks onto the road. The actions resulted in 11 arrests. The TMT company chairman stated: "T.M.T. will follow the process set forth by the state." A revised permit was approved on September 28, 2017, by the Hawaii Board of Land and Natural Resources. On December 2, 2015, the Hawaii State Supreme Court ruled the 2011 permit from the State of Hawaii Board of Land and Natural Resources (BLNR) was invalid ruling that due process was not followed when the Board approved the permit before the contested case hearing. The high court stated: "BLNR put the cart before the horse when it approved the permit before the contested case hearing," and "Once the permit was granted, Appellants were denied the most basic element of procedural due process – an opportunity to be heard at a meaningful time and in a meaningful manner. Our Constitution demands more". 2017-2019: BLNR hearings, Court validates revised permit In March 2017, the BLNR hearing officer, retired judge Riki May Amano, finished six months of hearings in Hilo, Hawaii, taking 44 days of testimony from 71 witnesses. On July 26, 2017, Amano filed her recommendation that the Land Board grant the construction permit. On September 28, 2017, the BLNR, acting on Amano's report, approved, by a vote of 5-2, a Conservation District Use Permit (CDUP) for the TMT. Numerous conditions, including the removal of three existing telescopes and an assertion that the TMT is to be the last telescope on the mountain, were attached to the permit. On October 30, 2018, the Supreme Court of Hawaii ruled 4-1, that the revised permit was acceptable, allowing construction to proceed. 2019 blockade and aftermath On July 15, 2019, renewed protests blocked the access road, again preventing construction from commencing. On July 17, 38 protestors were arrested, all of whom were kupuna (elders) as the blockage of the access road continued. The blockade lasted 4 weeks and shut down all 12 observatories on Mauna Kea, the longest shut down in the 50-year history of the observatories. The full shut down ended when state officials brokered a deal that included building a new road around the campsite of the demonstrations and providing a complete list of vehicles accessing the road to show they are not associated with the TMT. The protests were labeled a fight for indigenous rights and a field-defining moment for astronomy. While there is both native and non-native Hawaiian support for the TMT, a "substantial percentage of the native Hawaiian population" oppose the construction and see the proposal itself as a continued disregard to their basic rights. The 50 years of protests against the use of Mauna Kea has drawn into question the ethics of conducting research with telescopes on the mountain. The controversy is about more than the construction and is about generations of conflict between Native Hawaiians, the US Government and private interests. The American Astronomical Society stated through their Press Officer, Rick Fienberg; "The Hawaiian people have numerous legitimate grievances concerning the way they've been treated over the centuries. These grievances have simmered for many years, and when astronomers announced their intention to build a new giant telescope on Maunakea, things boiled over". On July 18, 2019, an online petition titled "Impeach Governor David Ige" was posted to Change.org. The petition gathered over 25,000 signatures. The governor and others in his administration received death threats over the construction of the telescope. On December 19, 2019, Hawaii Governor David Ige announced that the state would reduce its law enforcement personnel on Mauna Kea. At the same time, the TMT project stated it was not prepared to start construction anytime soon. 2020s Early in 2020, TMT and the Giant Magellan Telescope (GMT) jointly presented their science and technical readiness to the US National Academies Astro2020 panel. Chile is the site for GMT in the south and Mauna Kea is being considered as the primary site for TMT in the north. The panel has produced a series of recommendations for implementing a strategy and vision for the coming decade of US astronomy and astrophysics frontier research and prioritize projects for future funding. In July 2020, TMT confirmed it would not resume construction on TMT until 2021, at the earliest. The COVID-19 pandemic resulted in TMT's partnership working from home around the world and presented a public health threat as well as travel and logistical challenges. On August 13, 2020, the Speaker of the Hawaii House of Representatives, Scott Saiki announced that the National Science Foundation (NSF) has initiated an informal outreach process to engage stakeholders interested in the Thirty Meter Telescope project. After listening to and considering the stakeholders’ viewpoints, the NSF acknowledged a delay in the environmental review process for TMT while seeking to provide a more inclusive, meaningful, and culturally appropriate process. In November 2021, Fengchuan Liu was appointed the Project Manager of TMT and moved his office to Hilo. , no further construction was announced or initiated. Continued progress on instrument design, mirror casting and polishing, and other critical operational technicalities were worked through or were being worked on. In July 2023 a new state appointed board, the Maunakea Stewardship Oversight Authority, began a five-year transition to assume management over the Mauna Kea site and all telescopes on the mountain. While there are no specific timelines or schedules regarding new start or completion dates, activist Noe Noe Wong-Wilson is quoted by Astronomy magazine as saying, "It's still early in the life of the new authority, but there's actually a pathway forward." The authority includes representatives from Native Hawaiian communities and cultural practitioners as well as astronomers and others. The body will have full control of the site from July 2028. On December 2024, the NSF released the US Extremely Large Telescopes External Evaluation Panel Report on the TMT and the Giant Magellan Telescope (GMT) to assess their readiness to move into the major facility Final Design Phase. The panel noted that site access was an existential threat to TMT, and that mitigation for this risk in the form of the La Palma alternate site was insufficient. TMT's outreach was also unfavorably compared to the GMT, having been focused largely on Indigenous Hawaiians. In June 2025 the United States' National Science Foundation dropped support for the TMT in favor of the GMT. This lack of funding puts the TMT's future in doubt, although the scientists in the TMT international consortium said they would press forward. == Alternative site in the Canary Islands ==

In response to the ongoing protests that occurred in July 2019, the TMT project officials requested a building permit for a second site choice, the Spanish Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands. Rafael Rebolo, the director of the Instituto de Astrofísica de Canarias, confirmed that he had received a letter requesting a building permit for the site as a backup in case the Hawaii site cannot be constructed. Some astronomers argue however that La Palma is not an adequate site to build the telescope due to the island’s comparatively low elevation, which would enable water vapor to frequently interfere with observations due to water vapor’s tendency to absorb light at midinfrared wavelengths. Encinas ruled that the land concessions were invalid as they were not covered by an international treaty on scientific research and that the TMT International Observatory consortium did not express firm intent to build on the La Palma site as opposed to the site in Mauna Kea. On July 19, 2022, the National Science Foundation announced it will carry out a new environmental survey of the possible impacts of the construction of the Thirty Meter Telescope at proposed building sites at both Mauna Kea and at the Canary Islands. Continued funding for the telescope will not be considered prior to the results of the environmental survey, updates on the project's technical readiness, and comments from the public. ==See also==