VLT mirror handling

Handling VLT mirrors requires an extreme level of care — breaking one would result in far more than seven years of bad luck.

This photo shows one of the most dramatic moments of the handling of the fragile, 8.2-m Zerodur mirror for the UT1.

The 22-tonnes mirror has been lifted out of its transport box and is suspended over the floor of the main hall of the Mirror Maintenance Building (MMB). This facility is located at the Paranal Base Camp at the foot of the mountain and also houses the large coating plant in which a thin, highly reflective layer of aluminium will later be deposited on the mirror surface.

The Mirror Cell (to the left, on an air cushion carriage) is being moved under the mirror, after which it will be lowered onto its supports at the top of the cell.

The 150 cups attached to the inferior side of the mirror are well visible. They fit exactly into the 150 supports in the Cell and distribute the load of the mirror evenly.

At this moment, the thin mirror (177 mm) is suspended by a number of clamps along the rim and others at the central hole. It would not be possible to lift it with those at the rim or those at the hole alone - the mirror would then break under its own weight.