The Canada-France-Hawaii-Telescope Corporation (CFHT) plans to repurpose its observatory on the summit of Maunakea and operate a (60 segment) 11.25m aperture wide field spectroscopic survey telescope, the Maunakea Spectroscopic Explorer (MSE). The prime focus telescope will be equipped with dedicated instrumentation to take advantage of one of the best sites in the northern hemisphere and offer its users the ability to perform large surveys. Central themes of the development plan are reusing and upgrading wherever possible. MSE will reuse the CFHT site and build upon the existing observatory infrastructure, using the same building and telescope pier as CFHT, while minimizing environmental impact on the summit. MSE will require structural support upgrades to the building to meet the latest building seismic code requirements and accommodate a new larger telescope and upgraded enclosure. It will be necessary to replace the current dome since a larger slit opening is needed for a larger telescope. MSE will use a thermal management system to remove heat generated by loads from the building, flush excess heat from lower levels, and maintain the observing environment temperature. This paper describes the design approach for redeveloping the CFHT facility for MSE. Once the project is completed the new facility will be almost indistinguishable on the outside from the current CFHT observatory. Past experience and lessons learned from CFHT staff and the astronomical community will be used to create a modern, optimized, and transformative scientific data collecting machine.
The suspension and rotation systems (typically called bogies) for Extremely Large Telescope (ELT) enclosures will carry structures that are 2-3 times greater in diameter and much heavier than enclosures for the previous generation of 6-10m telescopes. Via on-site visits and/or engineering documentation, we have surveyed eleven optical, infrared, and submillimeter 3-15m telescope enclosures, and report on key design features of the suspension and rotation systems, including wheel and track geometry, the wheel/track interface, average load per wheel, rotation drive method, etc. We discuss key considerations for the development of future suspension and rotation systems for ELT enclosures.
The Maunakea Spectroscopic Explorer is designed to be the largest non-ELT optical/NIR astronomical telescope, and will be a fully dedicated facility for multi-object spectroscopy over a broad range of spectral resolutions. The MSE design has progressed from feasibility concept into its current baseline design where the system configuration of main systems such as telescope, enclosure, summit facilities and instrument are fully defined. This paper will describe the engineering development of the main systems, and discuss the trade studies to determine the optimal telescope and multiplexing designs and how their findings are incorporated in the current baseline design.
Over the past two years, the New York Astronomical Corporation (NYAC), the business arm of the Astronomical Society of New York (ASNY), has continued planning and technical studies toward construction of a 12-meter class optical telescope for the use of all New York universities and research institutions. Four significant technical studies have been performed investigating design opportunities for the facility, the dome, the telescope optics, and the telescope mount. The studies were funded by NYAC and performed by companies who have provided these subsystems for large astronomical telescopes in the past. In each case, innovative and cost effective approaches were identified, developed, analyzed, and initial cost estimates developed. As a group, the studies show promise that this telescope could be built at historically low prices. As the project continues forward, NYAC intends to broaden the collaboration, pursue funding, to continue to develop the telescope and instrument designs, and to further define the scientific mission. The vision of a historically large telescope dedicated to all New York institutions continues to grow and find new adherents.
The Maunakea Spectroscopic Explorer (MSE; formerly Next Generation Canada-France-Hawaii Telescope) is a dedicated, 10m aperture, wide-field, fiber-fed multi-object spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The enclosure vent configuration design study is the last of three studies to examine the technical feasibility of the proposed MSE baseline concept. The enclosure vent configuration study compares the aero-thermal performance of three enclosure ventilation configurations based on the predicted dome thermal seeing and air flow attenuation over the enclosure aperture opening of a Calotte design derived from computational fluid dynamics simulations. In addition, functional and operation considerations such as access and servicing of the three ventilation configurations is discussed.
The Next Generation Canada-France-Hawaii Telescope is a dedicated, 10m aperture, wide-field, fiber-fed multiobject
spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit
of Mauna Kea. The Next Generation Canada-France-Hawaii Telescope baseline concept assumes the new facility is
built on the existing Canada-France-Hawaii Telescope telescope pier and enclosure pier and occupies the same three
dimensional exterior “footprint”. Three technical studies have been planned to examine the validity of these
assumptions. The technical studies are executed in series as they represent technical decision points in a logical
sequence. The three technical studies in succession are: 1. Telescope Pier Study – Load Capacity and Structural
Interface, 2. Enclosure Fixed Base Study – Telescope and Enclosure Configuration and Load Capacity and 3. Aero-
Thermal Study – Dome Thermal Seeing and Air Flow Attenuation over the Enclosure Aperture Opening. The paper
outlines the baseline facility (telescope, spectrograph and enclosure) concept and the status of these studies, and
discusses the proposed telescope and enclosure configuration in terms of the redevelopment assumptions. A
consolidated feasibility study report will be submitted to the CFHT Board and Science Advisory Committee in the
Fall of 2012, with first light for the facility aiming to be in the early 2020s.
The enclosure design for the Thirty-Meter Telescope is now in final design phase. The focus of design activities now
turns to developing details and strategies enabling efficient manufacturing, construction and operations of the enclosure
on the selected Mauna Kea site. This paper provides an overview of the enclosure design and an outline of the proposed
The design of the calotte enclosure for the Thirty-Meter Telescope is currently in the preliminary design phase. Key
aspects of the design include an efficient structural/mechanical form, repetition of components, modular construction,
and operational efficiency. This paper includes an overall description of the enclosure design, as well as a description of
the major structural and mechanical subsystems. The enclosure incorporates features that influence the thermal and
aerodynamic environment of the telescope including ventilation openings and wind deflecting features. Other key
considerations of the preliminary design include the constructability and maintainability of a dynamic structure of this
scale at a remote mountain site.
The Thirty Meter Telescope (TMT) project has chosen a reference configuration with the telescope elevation axis above the primary mirror. The TMT telescope design has a segmented primary mirror, with 738 segments, nominally 1.2 m across corners, and it uses an articulated tertiary mirror to feed science light to predefined instrument positions on two large Nasmyth platforms. This paper outlines the development of the telescope structural design to meet the motion requirements related to the image quality error budget. The usage of opto-structural performance evaluation tools such as Merit Function Routine are described in addition with the optimization techniques used during the telescope structure design development.
Design of an extremely large optical telescope poses many technical challenges. One of these challenges includes the design of an enclosure that meets the necessary functional requirements while minimizing the financial cost. This study
describes the conceptual design of the Thirty Meter Telescope enclosure. Initially, four general enclosure styles were
considered including calotte, dome-shutter, carousel and co-rotating enclosure styles. Progressively detailed
comparative studies were completed to evaluate the structural, mechanical, aerodynamic, thermal and operational
characteristics of the candidates, and the associated capital and operational costs. As a result, the calotte enclosure was
selected as the preferred configuration to carry forward through the conceptual design phase. Continuing design and
analysis have brought all of the major calotte enclosure subsystems to a conceptual design level.
Cornell University and California Institute of Technology are currently studying the feasibility of constructing a 25
meter telescope to operate down to 200 micron wavelength to be sited on a high peak in the Atacama region of Chile.
An enclosure dome is required to protect the telescope from wind, solar heating, snow, and dust. A diameter of 50
meters at the equator is anticipated, larger than any existing opening telescope enclosure. A review of various
approaches indicates that a "calotte" type design, which uses two rotational axes to achieve full sky pointing, is
structurally and dynamically superior to other large enclosure approaches. The calotte design is balanced about both axes of rotation and features a circular aperture which provides optimal isolation from the wind. The nearly continuous
spherical shell lends itself to efficient space frame type structural form. An initial conceptual design was developed,
including structures, bearings, and drive systems. Analysis of these components was performed which illustrates the
feasibility of the chosen approach and provides indications of areas of critical risk in further development.
We describe the VLOT integrated model, which simulates the telescope optical performance under the influence of external disturbances including wind. Details of the implementation in the MATLAB/SIMULINK environment are given, and the data structures are described. The structural to optical interface is detailed, including a discussion of coordinate transformations. The optical model includes both an interface with ZEMAX to perform raytracing analysis and an efficient Linear Optics Model for producing telescope optical path differences from within MATLAB. An extensive set of optical analysis routines has been developed for use with the integrated model. The telescope finite element model, state-space formulation and the high fidelity 1500 mode modal state-space structural dynamics model are presented. Control systems and wind models are described. We present preliminary results, showing the delivered image quality under the influence of wind on the primary mirror, with and without primary mirror control.