Pasadena, CA – The teams working on TMT’s Segment Handling System (SHS) and utility system design received some good news following a series of critical review meetings earlier this spring. The TMT Telescope Structure Subsystem (STR) and Summit Facility (SUM) groups conducted the reviews and based on the outcome, the teams may now proceed independently with the final design of their systems toward production preparation.
TMT Segment Handling System
TMT’s SHS is an innovative robotic system developed by STR’s main contractor, Mitsubishi Electric (MELCO). The SHS robot is designed to safely and efficiently install and remove primary mirror (M1) segments with high precision. As shown in the animation below, for M1 removal, the SHS Main Bridge is deployed over the M1 surface and rotated to align with the Secondary Bridge that is deployed. The Segment Lifting Fixture (SLF) then translates from the Segment Handling Platform (SHP) across the Secondary Bridge and onto the Main Bridge. The Secondary Bridge retracts to allow the Main Bridge to rotate into position over the M1 segment to be exchanged. The SLF then traverses between the underside of the main bridge and the M1 surface and is positioned over the targeted M1 segment which is raised above the M1 surface. The SLF reaches down, grasps and lifts the targeted segment, which is then translated back over the M1 surface to the SHP after the Main and Secondary Bridges are realigned. The removed segment is offloaded onto a M1 handling yoke before it is lowered to the observatory floor. At that point, the Optics team takes the segment away and places a freshly recoated segment onto the M1 handling yoke for installation into the mirror cell by SHS.
Once operational, TMT plans to exchange about 10 segments every two weeks. At this rate, all 492 segments making up the full M1 mirror can be recoated and replaced within two years.
As described in the segment exchange sequence, the Secondary Bridge is deployed from the SHP and aligned with the Main Bridge. The interface between the Main and Secondary Bridges has been carefully designed and includes precise alignment tolerances for smooth Trolley transition across the bridges.
The review also focused on the requirements of the interface between the SHS and the M1 cleaning arms. “We have to make sure the segment handling system bridge and its components provide proper clearance to the four robotic cleaning arms that will regularly clean TMT’s primary mirror segments,” said John Rogers, Deputy Systems Engineering Group Leader. Hazard analysis and risk assessments were also reviewed to ensure reliable and maintainable robot operations.
“Many thanks to the MELCO, TMTJ STR, and TIO STR and SE teams for the effort and stellar work over the last five years to address all these STR structural and mechanical design challenges for production preparation,” said Telescope Structures Group Leader Kyle Kinoshita. “Congratulations on a job well done!”
Utility Services on TMT Telescope
The STR subsystem provides the infrastructure for all the services required for operating the observatory: lighting, electrical power and bonding/grounding, safety network, communication, software, chilled water, refrigerant system, compressed air and hydrostatic bearing system. These services are provided through cable trays, pipe racks, wraps, and support hardware, which are attached directly to the telescope structure and organized to maximize operations and maintenance efficiency of the observatory.
In most cases, electrical power and communications cables run in cable trays while kilometers of piping run coolant, cryogen and air to keep the telescope and instrumentation at a suitable temperature while securing optimal conditions for every system to operate smoothly. The TMT piping and cabling support structures and power distribution boards are designed to survive significant seismic events.
The TMT Telescope Structure team successfully verified that (1) the Telescope Utility Services are compliant with standard safety codes to ensure the safety of the personnel and the protection of the mirrors and all critical observatory components, and (2) that all recommendations and actions had been implemented to complete the final design of the Telescope Utility Services.
Utility Services at the Summit Facility Building
In addition to the Telescope Utility Services, the review team also addressed the Summit Facility Utilities, which provide and distribute the services required for all operations taking place within the summit facility building. This facility hosts all equipment and infrastructure needed to support TMT summit operations, including administrative spaces, control room, mirror coating facilities and the mechanical and utility rooms.
This part of the review covered the design of the summit facilities, including the equipment and lines connecting to the Telescope Structure (STR). All of the telescope utilities from the facility building will go through the service tunnel, running below the observing floor, to reach the pier area and telescope structure within the enclosure.