What operators call a "strong back" is an extremely rigid circular lifting device that interfaces with the component through 18 attachments, equally distributed around its circumference. The 23-tonne device is attached to the overhead crane by a single hook, which facilitates the centring of the load and ensures perfect balance.
Attached to its ''strong back,'' the 50-tonne lower cryostat thermal shield has reached cruising altitude (23 metres) and speed (2 metres/minute). Its silvery surface reflects the colours, lights and distorted shapes of the environment.
When the component was positioned directly above the pit, it remained stationary for a time as real-time metrology was performed once again. During its transfer however, the load had rotated a few degrees and the temporary vertical rails inside the component, designed to fit into the guiding device of the "alignment tools" at the bottom of the pit, were slightly off target.
The component has travelled the whole length of the assembly theatre and is now positioned right above the pit. Two alignment tools, visible at the bottom of the large circular opening, will guide its final trajectory.
As the load is being transferred from the crane to an array of hydraulic jacks, a full-day operation comes to an end. A few more adjustments and final metrology and the day will be declared a success.