The 4.2 m Discovery Channel Telescope requirements create interesting challenges for the Mount mechanical and control system design. The wide field of view survey telescope incorporates two operational foci: prime focus and cassegrain, either one must be available during any night's observing. The mission for observing requires fast slewing / offsets between each exposure with fast settling times to maintain the mission requirements. The prime focus arrangement includes a dedicated camera on the spider assembly and the cassegrain configuration includes a secondary mirror at the spider assembly with a dedicated instrument located at the cassegrain focus. This requirement challenges the design team to incorporate a prime focus / secondary mirror flipping mechanism within the secondary spider. The configuration requires a substantial prime focus and cassegrain payload with long focal distances creating a large inertia on the altitude axis. These are a few of the interesting challenges that are presented in this paper along with the design, trade-offs of different solutions, and the recommended design for the telescope Mount.
VertexRSI completed the 4.2-meter Southern Astrophysical Research (SOAR) Telescope Mount in 2001. The Mount is now in assembly and test at the site in Chile. This paper will discuss the final mechanical design of the Mount and the implementation of the design requirements during fabrication, factory integration and testing. The final design includes detailed finite element structural analysis, 3-D design models, and precise machining requirements. These requirements were implemented in the fabrication using standard and novel machining approaches. Factory integration proved out the design and fabrication process. The connection of these items with the success of the testing is presented.
The SOAR telescope dome is a 20 meter diameter 5/8 spherical structure built on a rotating steel frame with an over the top nesting shutter and covered with a fiberglass panel system. The insulated fiberglass panel system can be self- supporting and is typically used for radomes on ground based tracking systems. The enclosed observing area is ventilated using a down draft ventilation system. The rotating steel frame is comprised of a ring beam and dual arch girders to provide support to the panel system sections and guide the shutter. The dual door shutter incorporates a unique differential drive system that reduces the complexity of the control system. The dome, shutter and windscreen `track' the telescope for maximum wind protection. The dome rotates on sixteen fixed compliant bogie assemblies. The dome is designed for assembly in sections off the facility and lifted into place for minimal impact on assembly of other telescope systems. The expected cost of the complete dome; including structure, drives, and controls is under 1.7 million. The details covered in this paper are the initial trade-offs and rationale required by SOAR to define the dome, the detailed design performed by M3 Engineering and Technology, and the choices made during the design.
The next generation large telescope is expected to be on the order of a 20 to 50 meter diameter aperture. The facilities required for these large telescopes must be structurally efficient in design to be cost effective. A geodesic type, rotating aluminum dome is one possibility. A geodesic structure has the advantages of high specific strength and stiffness, easy of deployment to the site, rapid on-site assembly and installation in parallel with other telescope assembly tasks, and long life. This paper presents a feasibility study, cost estimates, and concept design for a 91 meters (300 feet) diameter geodesic aluminum dome suitable for the next generation large telescopes.
A large prime-focus robotic star tracking device has been designed and constructed and is now undergoing commissioning atop the 9.2-meter Hobby-Eberly Telescope at McDonald Observatory in West Texas. The novel, cost-effective tracker represents a major departure in the way very large astronomical telescopes are controlled in pointing, tracking, and guiding. The tracker development and design implementation included detailed structural analysis, the application of minimum constraint kinematic design to a large gantry-type motion control system, and the unique application of a large precision hexapod to solve the dynamic tilting and focus motion problems. Challenging fabrication, test, and on-telescope assembly problems were overcome. Performance data of the completed device demonstrate that the tracker design and implementation efforts were successful.