CATAC Update on the Thirty Meter Telescope

By Michael Balogh (CATAC Chair)
(Cassiopeia – Autumn 2023)

Background Summary of the TMT Project

Recognizing that the Thirty Metre Telescope (TMT) is a project spanning multiple decades, many people new to the astronomy community will be unfamiliar with its history. Following is a short summary of the project’s background, with links to more information. Current updates detailing developments since our last report follow this background.

current news follows summary

The TMT is a proposed 30-m diameter, optical telescope with a state-of-the-art adaptive optics system that will achieve unprecedented sensitivity and resolution. It will enable transformative discoveries in a wide range of disciplines including exoplanets and the search for biomarkers, cosmology and the formation of the Universe, galaxies and stars, and much more, as described in the Detailed Science Case. TMT is one of only three planned telescopes of this type. The others are the 25-m Giant Magellan Telescope (GMT) and the 42-m European Extremely Large Telescope (ELT).

Canada has been engaged in the TMT project since 2003, with a significant scientific and technical leadership role. Canada joined the TMT International Observatory (TIO) corporation as a full member in 2015, following a $243M commitment from the federal government. These funds primarily support construction of the enclosure by Canadian industry, and the adaptive optics system, NFIRAOS, by Herzberg Astronomy and Astrophysics (HAA). Participation in the TMT has been strongly endorsed by the Long Range Planning exercise, starting with the midterm review in 2005. Canada has three seats on the TMT Board: the ACURA Executive Director (Gilles Joncas), the HAA Director General (Luc Simard); and a Science Governor (currently vacant). Canada also has three voting seats on the Science Advisory Committee, and one non-voting position usually occupied by the Science Governor. Canada’s share of observing time is expected to be in the range of 10-15%, though this depends on the outcome of negotiations for NSF partnership, and the final project cost.

TMT is a technically mature project, but construction requires both significant additional funding, and the support of the local community. Protests against TMT construction in 2014 and 2019 have prevented construction from proceeding. The position of CASCA and ACURA, endorsed by CATAC, is that unless the TMT project has consent from the Native Hawaiians, Canada’s astronomical community cannot support its construction on Maunakea. Several important changes have taken place since 2019, including the establishment of the Mauna Kea Stewardship and Oversight Authority (MKSOA). The formation of this body was recommended by a Working Group initiated by the State Governor, and signed into law on July 7, 2022. This Authority began work on July 1, 2023, and will take over management of the mountain from the University of Hawaii after a transition period of no more than five years. This Authority includes Native Hawaiian representatives and cultural practitioners, giving them a direct role in the management of these lands, including the issuing of leases to astronomy facilities.

The US Extremely Large Telescope Program (US-ELTP) is a partnership between TMT, the Giant Magellan Telescope (GMT) and NOIRLab, to advance US access to 30-m class telescopes in both hemispheres. A proposal to the NSF has led to a formal review of the project by that body, under the MREFC process. Following a recommendation by the US Astro2020 review, the NSF is considering a significant share of at least 25% in each of TMT and GMT. The review process includes federal environmental and cultural reviews, under the National Historic Preservation Act and the National Environmental Policy Act.

TMT does have legal right to construct on an alternative site, on La Palma, Canary Islands. There are still associated environmental, political and social complications, including motivated environmental groups opposing construction. The NSF review process is currently limited to Maunakea as a potential site.

Construction cannot begin until the NSF Final Design Phase is completed – a necessary but not sufficient condition. This phase nominally takes 1.5 years, and has not started yet. Assuming seven years for construction, the earliest possible first light date for TMT is 2033. Technical first light for the European ELT is planned for 2027, with the first four instruments commissioned and ready for science by 2030. It is disappointing to be behind the ELT, when at one point (in 2014) TMT was so far ahead. However, CATAC is mindful that these facilities have anticipated lifetimes of >40 years, serve very large communities and that current anticipated first light dates are subject to change.

Further information can be found on the TMT website. Previous CATAC reports and eCass articles can be found here.

Project Status

Earlier this year, the US National Science Foundation (NSF) completed a Preliminary Design Review (PDR) of the US Extremely Large Telescope Program (US-ELTP). The report was positive, and it is expected that a recommendation will be made to the National Science Board (NSB) to move into the Final Design Review (FDR) stage. The next meeting of the NSB is Nov 29-30, 2023.

The NSF Environmental Impact Statement (EIS) and Section 106 process continues, with updates and FAQ provided here. This process continues to move slowly, due in part to the large volume of comments submitted during the scoping process.

While the NSF process takes place, the corresponding delay to TMT construction is of concern, as the potential for a large gap between E-ELT and TMT first light dates grows. LRP recommendation #16 reads:

We recommend that NRC address any lack of access to a VLOT due to delays in TMT construction through arrangements that give Canadians access to other VLOT facilities.

CATAC looks forward to participating in future discussions with HAA and the astronomy community about this recommendation.

As part of the NSF review process, the TMT Detailed Science Case is being updated, led by the International Science Development Teams (ISDTs). All chapter editors have now been identified. The plan is to deliver a complete draft by the end of 2023 for review and comments.


The Mauna Kea Stewardship and Oversight Authority (MKSOA) began their work on July 1, 2023, and are in the process of hiring staff. Full transfer of authority from the University of Hawaii to MKSOA will happen within five years; no new leases or subleases may be signed before then. It is still too early to know if there will be a process for lease negotiation in the interim.

The Caltech Submillimeter Observatory (CSO) is on path to be decommissioned this year, with the telescope itself being removed this month. Detailed, up to date information about the process is available at the CSO website.

On July 14, a petition was filed to the United Nations Committee on the Elimination of Racial Discrimination (CERD), requesting a decision under the Early Warning and Urgent Action Procedures (EWUAP). The request is a joint submission from three petitioners: KAHEA: The Hawaiian-Environmental Alliance, (2) Ziibiing Lab: Global Indigenous Politics Research Collaboratory, and (3) the Transnational Law and Racial Justice Network (TLRJN). Among other things, the petition requests that CERD urge Canada to divest support from TMT. This petition is now before CERD and the process, which can take several years, is a closed one between the committee and the Canadian government. ACURA’s response to this petition, and the petition itself, can be found here.

Upcoming Workshops

There will be three ELT-JWST synergy workshops: one in North America, one in Asia, and one in Europe. Registration is open for the first, to be held at UCLA Dec 11-15, 2023: “The Landscape for ELTs after the launch of JWST.” Canadians are strongly encouraged to attend. Some travel support may be available – please contact for more information. The European and Asian meetings are anticipated to be held in 2024.

The last TMT Science Forum was in China in 2019. Plans to hold one in Canada in 2021 were postponed due to COVID and then finally cancelled in 2022. It is now anticipated that the next forum will be held in Washington, D.C., in late 2024.

CATAC Membership Changes

After six years of excellent service, inaugural CATAC member Harvey Richer has come to the end of his term. We are grateful for his work on this committee, and in particular for leading the effort to host the Science Forum in Vancouver, unfortunately thwarted by the pandemic. ACURA has nominated Suresh Sivanandam (U Toronto) to take Harvey’s place on CATAC.

Gilles Joncas has replaced Don Brooks as ACURA Executive Director and serves on CATAC in a non-voting, ex-officio role. Similarly, as CASCA President, Sarah Gallagher takes over from Chris Wilson.

CATAC Membership

Michael Balogh (University of Waterloo), Chair,
Bob Abraham (University of Toronto; TIO SAC)
Stefi Baum (University of Manitoba)
Laura Ferrarese (NRC)
Suresh Sivanandam (University of Toronto)
Jason Rowe (Bishop’s)
Stan Metchev (Western University; TIO SAC Canadian co-chair)
Gilles Joncas (ACURA Executive Director, non-voting, ex-officio)
Luc Simard (Director General of NRC-HAA, non-voting, ex-officio)
Sarah Gallagher (CASCA President, non-voting, ex-officio)
Tim Davidge (TIO SAC; NRC, observer)

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