Proceedings Article | 18 July 2018
KEYWORDS: Telescopes, Large Synoptic Survey Telescope, Cameras, Optical instrument design, Mirrors, Control systems design, Motion controllers, Control systems, Optical fabrication, Capacitors
On June 9th, 2014, the design/build contract for the Large Synoptic Survey Telescope (LSST) Mount Assembly (TMA) system was awarded to GHESA Ingeniería y Tecnología, S.A. and Asturfeito, S.A. This paper describes the current status of the fabrication, assembly, and verification, along with the logistic plans to ship the mount and equipment to Cerro Pachón in Chile. The design of the mount successfully passed the final design review on January 29, 2016, and is currently under full-scale construction at Asturfeito’s factory in Avilés, Spain.
A detailed description the critical design, fabrication challenges, and the state of testing is presented for the following subsystems:
Azimuth track assembly: The 16-m diameter azimuth track which was fabricated in four large sectors provides the mounting surfaces for the axial and radial hydrostatic bearings. This high precision surface has been machined to high flatness and circularity to meet the high pointing repeatability requirements.
Azimuth structure: The azimuth structure consists of 20 large weldments. These large heat-treated weldments were designed to minimize pointing hysteresis and yet be small enough to be transported by truck.
Elevation structure: The elevation structure consists of a large central ring structure that supports both the M1M3 mirror cell and the optical support for the M2 and camera.
Azimuth mechanicals: The azimuth structure uses 16 linear motors designed and fabricated by Phase Motion Control. All motors, motion control, and capacitor banks have been delivered to the factory and are being prepared for installation
Hydrostatic bearings: All hydrostatic bearings have been designed and fabricated by SKF. The oil supply system was designed by SKF and HYDX hydraulic solutions. The azimuth bearings have been installed and tested using the azimuth platform.
Mount control system hardware and software: The hardware, engineering interface and the software that connects to the telescope control system was designed, assembled, and tested by iK4 Tekniker. This system has been tested using the camera cable wrap and the M1M3 mirror covers at Tekniker. The system is now being installed the factory to begin testing on the assembled mount.
Camera cable wrap: The top end of the telescope requires a complex cable wrap for all of the cameras services and utilities. This wrap successfully passed verification testing and is now installed on the telescope top end.
M1M3 mirror cover: This unique four-fan design was developed and tested at ik4 Tekniker. After verification at Tekniker it was shipped to the factory and is now assembled on the azimuth ring assembly.
Utility distribution: Fluid distribution system includes a large network of coolants, refrigerants, air, fibers optics, and data communication lines. The unique challenges to routing throughout the telescope all of these services required coordinated design and implementation and four cable wraps. The azimuth cable wrap is a motorized drape design designed by Empresarios Agrupados and Tekniker. The two elevation drapes were designed by Empresarios Agrupados and Kabbleschlepp.
An overview of the logistics required for shipping, ground transportation, and cranes will be described.
