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Preliminary Design Study of the TMT Telescope Structure System: Overview

Usuda, Tomonori and Ezaki, Yutaka and Kawaguchi, Noburu and Nagae, Kazuhiro and Kato, Atsushi and Takaki, Junji and Hirano, Masaki and Hattori, Tomoya and Tabata, Masaki and Horiuchi, Yasushi and Saruta, Yusuke and Sofuku, Satoru and Itoh, Noboru and Oshima, Takeharu and Takanezawa, Takashi and Endo, Makoto and Inatani, Junji and Iye, Masanori and Sadjadpour, Amir and Sirota, Mark and Roberts, Scott and Stepp, Larry (2014) Preliminary Design Study of the TMT Telescope Structure System: Overview. In: Ground-Based and Airborne Telescopes V. Proceedings of SPIE. No.9145. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 91452F. ISBN 978-0-8194-9613-3.

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We present an overview of the preliminary design of the Telescope Structure System (STR) of Thirty Meter Telescope (TMT). NAOJ was given responsibility for the TMT STR in early 2012 and engaged Mitsubishi Electric Corporation (MELCO) to take over the preliminary design work. MELCO performed a comprehensive preliminary design study in 2012 and 2013 and the design successfully passed its Preliminary Design Review (PDR) in November 2013 and April 2014. Design optimizations were pursued to better meet the design requirements and improvements were made in the designs of many of the telescope subsystems as follows: 1. 6-legged Top End configuration to support secondary mirror (M2) in order to reduce deformation of the Top End and to keep the same 4% blockage of the full aperture as the previous STR design. 2. “Double Lower Tube” of the elevation (EL) structure to reduce the required stroke of the primary mirror (M1) actuators to compensate the primary mirror cell (M1 Cell) deformation caused during the EL angle change in accordance with the requirements. 3. M1 Segment Handling System (SHS) to be able to make removing and installing 10 Mirror Segment Assemblies per day safely and with ease over M1 area where access of personnel is extremely difficult. This requires semi-automatic sequence operation and a robotic Segment Lifting Fixture (SLF) designed based on the Compliance Control System, developed for controlling industrial robots, with a mechanism to enable precise control within the six degrees of freedom of position control. 4. CO2 snow cleaning system to clean M1 every few weeks that is similar to the mechanical system that has been used at Subaru Telescope. 5. Seismic isolation and restraint systems with respect to safety; the maximum acceleration allowed for M1, M2, tertiary mirror (M3), LGSF, and science instruments in 1,000 year return period earthquakes are defined in the requirements. The Seismic requirements apply to any EL angle, regardless of the operational status of Hydro Static Bearing (HSB) system and stow lock pins. In order to find a practical solution, design optimization study for seismic risk mitigation was carried out extensively, including the performing of dynamic response analyses of the STR system under the time dependent acceleration profile of seven major earthquakes. The work is now moving to the final design phase from April 2014 for two years.

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Additional Information:© 2014 SPIE. We gratefully acknowledge the support of the TMT collaborating institutions. They are the Association of Canadian Universities for Research in Astronomy (ACURA), the California Institute of Technology, the University of California, the National Astronomical Observatory of Japan, the National Astronomical Observatories of China and their consortium partners, and the Department of Science and Technology of India and their supported institutes. This work was supported as well by the Gordon and Betty Moore Foundation, the Canada Foundation for Innovation, the Ontario Ministry of Research and Innovation, the National Research Council of Canada, the Natural Sciences and Engineering Research Council of Canada, the British Columbia Knowledge Development Fund, the Association of Universities for Research in Astronomy (AURA), the U.S. National Science Foundation and the National Institutes of Natural Sciences of Japan.
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Ontario Ministry of Research and InnovationUNSPECIFIED
National Research Council of CanadaUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
British Columbia Knowledge Development FundUNSPECIFIED
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
National Institutes of Natural Sciences of JapanUNSPECIFIED
Association of Canadian Universities for Research in Astronomy (ACURA)UNSPECIFIED
University of CaliforniaUNSPECIFIED
National Astronomical Observatory of JapanUNSPECIFIED
National Astronomical Observatories of ChinaUNSPECIFIED
Department of Science and Technology of IndiaUNSPECIFIED
Subject Keywords:Astronomy; Ground based Extremely Large Telescope (ELT); Telescope Structure; Mount Control System; Segment Handling System; Seismic risk mitigation
Series Name:Proceedings of SPIE
Issue or Number:9145
Record Number:CaltechAUTHORS:20150615-130558332
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Official Citation:Tomonori Usuda ; Yutaka Ezaki ; Noboru Kawaguchi ; Kazuhiro Nagae ; Atsushi Kato ; Junji Takaki ; Masaki Hirano ; Tomoya Hattori ; Masaki Tabata ; Yasushi Horiuchi ; Yusuke Saruta ; Satoru Sofuku ; Noboru Itoh ; Takeharu Oshima ; Takashi Takanezawa ; Makoto Endo ; Junji Inatani ; Masanori Iye ; Amir Sadjadpour ; Mark Sirota ; Scott Roberts ; Larry Stepp; Preliminary design study of the TMT Telescope structure system: overview . Proc. SPIE 9145, Ground-based and Airborne Telescopes V, 91452F (July 22, 2014); doi:10.1117/12.2055767
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58254
Deposited By: Jason Perez
Deposited On:19 Jun 2015 14:37
Last Modified:03 Oct 2019 08:34

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