News

Updates for TMT Telescope Structure and Utility Services

October 12th, 2022 • Engineering & Technology

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.

TMT Segment Exchange Animation.
TMT SHS robot travels along the Main and Secondary Bridges of the telescope structure and lifts out a segment from the mirror cell. The mirror segment is then transitioned to the SHP and lowered down to the observatory floor for recoating.
Credit: TMT International Observatory

TMT Segment Handling System Trolley design

TMT Segment Handling System Design - The Trolley supports the Segment Lifting Fixture and moves along the Secondary and Main Bridges to exchange primary mirror segments. Image Credit: TMT International Observatory / NAOJ-MELCO

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.

Key subsystems of the TMT Segment Handling System - TMT Segment Handling System Main and Secondary Bridges support the Trolley, which carries the robotic Segment Lifting Fixture that removes and installs M1 segments. Image Credit: TMT International Observatory / NAOJ-MELCO

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.

Segment Handling System Final Design Interim Review, March 2022 - Screenshot of the participants from NAOJ, MELCO, TMT Structure and Systems Engineering teams who assessed the progress of the SHS mechanical and structural design, and supporting documentation - Image credit: TMT International Observatory

“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.

View diagram of routes for TMT utility services - Global view of utilities pipes and cable trays, electrical cabinets, and storage tanks. All TMT telescope utilities pass through the azimuth wraps and are routed across the azimuth structure and to the lower levels of the Nasmyth platforms for distribution to the instruments and other systems mounted on the Nasmyth Platforms. Utilities are also sent to the equipment carrying all the telescope optics on the elevation structure - Image credit: TMT International Observatory / NAOJ

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^{^[1]}.

TMT Structure Telescope Utility Services (TUS) Final Design Review 1 closeout meeting, 15 March 2022 - Screenshot of the participants from NAOJ, MELCO, and TMT attending the meeting held via remote participation - Image credit: TMT International Observatory

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.

TMT Summit Facilities Design - TMT summit facilities accommodate all utilities needed for on-site operations of the telescope including pumps, compressors, refrigeration systems, power and computer facilities, control room, offices, workshops, kitchen, receiving area and more. The current design of the facilities has not been finalized yet - Image Credit: TMT International Observatory

^{^[1]} TMT News: TMT’s Telescope Utility Services Final Design Reaches Huge Milestone, https://www.tmt.org/news/480, January 2021