The LSST secondary mirror (M2) substrate has been safely relocated from Harvard University in Cambridge, MA to the Exelis facility in Rochester, NY. The mirror’s trek, which involved the use of a 50-ton internal bridge crane to load the mirror transport box onto a wide-load flatbed truck and a 70-ton external crane to offload it at destination, covered 604 miles in a little over a day. The truck and pilot vehicle departed Harvard at 1 pm on October 20 and arrived in Rochester at 3 pm on October 21. Subsequently, Exelis personnel have disassembled the transport box and thoroughly inspected the substrate.
LSST Head of Safety Chuck Gessner observed the loading of the M2 transport box from Harvard Physics Lab storage onto the truck. LSST Telescope and Site Subsystem Manager Bill Gressler observed the mirror’s offloading at Exelis’ receiving area. Accelerometers were used to monitor and record acceleration, temperature, and movement forces on the mirror during its road trip. Neither the active nor the passive accelerometers indicated any problems during transport.
Delivery of the M2 substrate to Exelis highlighted the kick-off of the M2 Cell Assembly Fabrication effort. Exelis has been awarded the contract to process the M2 substrate to a finished polished state and also to provide final design, fabrication, assembly, test, and delivery of the M2 Cell Assembly. The M2 assembly will ultimately be integrated onto the telescope on Cerro Pachón in Chile. The 3.4-meter diameter mirror is a solid meniscus design fabricated from ultra low expansion (ULE™) glass manufactured by Corning Incorporated, Corning, NY.
The photo at left shows the M2 backing into the Exelis loading dock after being transferred via 70-ton external crane to an adjustable height trailer.