TMT Construction Proposal - Thirty Meter Telescope

1.2.6 Site
Ultimately, the performance of any optical-IR ground-based observatory is limited by its location. Currently,
TMT is executing a multi-year site testing program on five different mountains determined from satellite imagery
and meteorological data to have excellent potential. Final site selection is planned for mid-2008.
Location also has an impact on design and cost. For the purposes of detailed preliminary design, Cerro
Armazones in northern Chile has been chosen as the design reference site. This choice does not unduly
constrain the ultimate TMT site decision but does allow the kind of planning necessary to better define
requirements and estimate cost. Cerro Armazones is a good model for the Mexican site and other Chilean sites
under consideration. Relative to Armazones, the Hawaiian site under consideration is expected to have
somewhat reduced infrastructure requirements and hence lower cost. However, much of this cost differential is
reduced by cost rate differences in several key areas. In short, cost estimates for Cerro Armazones are
expected to be broadly applicable for all sites under consideration.
1.3 The TMT Project
The TMT Project was constituted to design and build the TMT Observatory as well as initiate early operations.
The project is nearing completion of site-independent design and development work. During this phase, we
have delivered a successfully reviewed conceptual design, a rigorous cost estimate, and carried out a value
engineering study resulting in a design optimization that retains the full science capabilities consistent with the
partner cost targets.
By early 2008, the project will provide the TMT Board with the information necessary to make a definitive site
selection and prepare for the transition to an implementation program that consists of three, overlapping
phases. First, completing site-specific facility design, industrializing production of the key TMT components,
producing first articles and carrying out low-rate initial production will bring all elements of the project to full
construction readiness. Second, construction will consist of full production of the serial elements of the primary
mirror (mirror segments, supports and controls, actuators, edge sensors and incidental components),
fabrication of all other technical elements, civil construction of summit and support facilities, erection of the
telescope enclosure and structure, and assembly, integration and verification of the complete system at the
observatory site. Finally, early operations will overlap construction as facilities are progressively delivered to
routine operations and as science capabilities are fully commissioned. Completion of these three phases will
enable full scientific operation of the TMT observatory.
1.4 The TMT Construction Proposal
In this document, we summarize work completed to date and provide an implementation roadmap. We start
with the science cases and science-driven requirements that motivate the TMT design. This is followed by highlevel
operational concepts, technical requirements, and observatory architecture description. Detailed
descriptions of the observatory sub-systems are followed by concepts for system assembly, integration and
verification followed by a description of how the observatory will be operated. We conclude with an overview of
how the project will be organized and a summary of project cost.
We intend to update this proposal over the next 12 – 18 months as TMT design work and implementation
planning are completed.
References
[1] Astronomy and Astrophysics in the New Millennium, Prepared by the National Research Council; the
Commission on Physical Sciences, Mathematics, and Applications (CPSMA); the Board on Physics and
Astronomy (BPA); and the Space Studies Board (SSB). The National Academies Press (2001).
[2] Science Advisory Committee (SAC) Report to the TMT Board, 23 Jan 2007, pg. 10, TMT.PSC.PRE.07.015.
[3] The Design and Construction of Large Optical Telescopes, Pierre Y. Bely, Editor, Springer (2002).
[4] Stepp, L., Daggert, L. and Gillett, P., "Estimating the costs of extremely large telescopes". Proc. SPIE 4840,
(2002).
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