The National Astronomical Observatory of Japan (NAOJ) has been responsible for the telescope structure subsystem (STR) of the Thirty Meter Telescope since 2012 and has engaged Mitsubishi Electric Corporation (MELCO) for preliminary and final design and pre-production work. There are various subsystems on the telescope, such as instruments and moving optics. Power and fluids and other services are required to operate these subsystems and the telescope drives. TMT provides the following services: Electrical Power and Bonding/Grounding, Fire Alarm, Communication and Information System (CIS) Networks, Fixed Temperature Chilled Water (FTCW) and Variable Temperature Chilled Water (VTCW), Hydrostatic Bearing System (HBS) Oil, Facility Compressed Air (FCA), Cryogenic System (CRYO), Refrigerant System (REFR), and Lighting (Operational and Emergency). The TMT defines the Telescope Utility Services (TUS) as the infrastructure which includes the cables and pipes used to deliver these utilities, the structures that support and route them, and the other components (electrical or piping components such as electrical cabinets or manifolds, lighting fixtures, fire alarms, etc.) necessary to provide these services. The design work to attach the TUS components to the STR was complicated due to the wide variety of TUS components and the multitude of mounting configurations and locations throughout the telescope structure. In order to efficiently integrate the various types of TUS components onto the STR, several practices were established and refined in the development of the TUS and STR design: 1. Definition of SOW between TUS and STR to enable concurrent TUS and STR design development 2. Simultaneous development of TUS and STR using CAD model 3. Piping and Cabling allocation within the Azimuth/Elevation Wrap 4. Route planning for cabling and piping 5. Seismic evaluation of TUS components In this paper we present the approach and the design implementation of the TUS components onto the STR.
National Astronomical Observatory of Japan (NAOJ) is responsible for procuring the Telescope Structure System (STR) of the Thirty Meter Telescope (TMT) and engaged Mitsubishi Electric Corporation (MELCO) to perform the preliminary/final design and production readiness work since 2012. The final design of the TMT STR was deemed completed through a series of external design reviews covering structural and mechanical, controls, and auxiliary systems such as the Segment Handling System (SHS), Aerial Service Platform (ASP), Elevator (ELV), safety, and the seismic isolation system. TMT STR is currently in the production readiness phase and has already passed the Production Readiness Reviews (PRRs) for major rotating mechanical structures. In this paper we present an overview of the design progress of the TMT STR, matured through extensive studies, performance assessments, and design budgets derived from bottoms-up analyses. Additionally, we discuss prototype activities to mitigate risks to performance and manufacturability of complex designs, along with the current programmatic status of the project.
Hazard and Risk Assessment (HARA) is a critical Systems Engineering and safety activity used to ensure a safe environment for personnel and hardware. This paper discusses how TMT has tailored the Atlassian Jira tool and third-party embedded app, SoftComply Risk Manager, to provide a collaborative environment with subsystem teams in order to a develop a comprehensive HARA, starting with hazard identification and assessment and continuing through reassessment after mitigation. The paper shows how the tool was initially created for the Telescope Structure (STR) to facilitate collaboration with the National Astronomical Observatory of Japan (NAOJ) and Mitsubishi Electric Corporation (MELCO), and has since expanded to other subsystems as well as to the system-level, capturing intersystem hazards. From the system and subsystem HARAs, risk reduction actions are identified and if safety functions are used as a mitigation, they are described in terms of functional safety actions and associated SIL ratings. These safety functions are then traced to safety requirements imposed on the Observatory Safety System or on subsystems. This overall HARA process provides TMT with a comprehensive overview of all Observatory hazards and the status of the development and implementation of their mitigations thanks to the Jira and Risk Manager dashboards, risk matrix, and risk table views.
Not coincidentally, most of the world’s best astronomical sites are in seismically active areas. As telescopes increase in aperture, they become increasingly sensitive to seismic loads. In this workshop, we want to collect the knowledge, experience, and lessons learned from the previous generations of observatories, to inform the design and construction of future observatories, including the ELTs (ELT, GMT, and TMT). Topics for the workshop include earthquake-induced damage to observatories (telescopes, instruments, enclosures), seismic protection systems and improvements in existing observatories, design of seismic protection systems for new and future observatories, processes and operational procedures for recovery and return to operations following seismic events, and lessons learned that can be applied to the design and operation of future observatories.
National Astronomical Observatory of Japan (NAOJ) has had the responsibility for the Telescope Structure System (STR) of Thirty Meter Telescope (TMT) and engaged Mitsubishi Electric Corporation (MELCO) to take over the preliminary/final design and pre-production work since 2012. TMT defines that STR shall be designed to withstand earthquakes up to the levels of the 1000-years annual return period as keeping accelerations at the mirror/instrumental interface points below the specified thresholds. In this paper, we present the Seismic Isolation System (SIS) of TMT STR, as focusing on (1) the design to achieve compatibility of two conflicting performances that are the rigid connection to the ground during normal observations and flexible movement during seismic to suppress the seismic energy, (2) prototype results of the seismic isolation system, and (3) compliance status of the seismic requirements which is evaluated by time history analysis using the Finite Element Method (FEM) model of TMT STR.
The thermal behavior of the Thirty Meter Telescope (TMT) Telescope Structure (STR) and the STR mounted subsystems
depends on the heat load of the System, the thermal properties of component materials and the environment as
well as their interactions through convection, conduction and radiation.
In this paper the thermal environment is described and the latest three-dimensional Computational Solid Dynamics
(CSD) model is presented. The model tracks the diurnal temperature variation of the STR and the corresponding
deformations. The resulting displacements are fed into the TMT Merit Function Routine (MFR), which converts them
into translations and rotations of the optical surfaces. They, in turn, are multiplied by the TMT optical sensitivity matrix
that delivers the corresponding pointing error. Thus the thermal performance of the structure can be assessed for
requirement compliance, thermal drift correction strategies and look-up tables can be developed and design guidance can
be provided.
Results for a representative diurnal cycle based on measured temperature data from the TMT site on Mauna Kea and
CFD simulations are presented and conclusions are drawn.
KEYWORDS: Telescopes, Optical instrument design, Computer aided design, Mirrors, Electroluminescence, Control systems design, Control systems, Earthquakes, Safety, Thirty Meter Telescope
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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