eso9810 — Organisation Release
Another Job Well Done at Paranal
M1 Mirror Cell and Dummy 8.2-m Mirror Attached to First Telescope
10 March 1998
The VLT assembly work at the ESO Paranal Observatory continues in great strides. During the past week, the mirror cell for the 8.2-m main mirror (the M1 cell ) was successfully attached to the bottom of the telescope tube of Unit Telescope 1 (UT1). The present `picture story' illustrates the various phases of this delicate operation.
For this, a dummy concrete mirror of the same size and weight as the main Zerodur mirror was placed in the M1 cell. This allowed the members of the technical crew to familiarize themselves with the various steps of this complex operation without any risk to the precious Zerodur mirror. This is still stored in its protective box outside the Mirror Maintenance Building (MMB) after the transport to Paranal.
The operation began inside the MMB at the base camp by lowering the 22 tons, 8.2-m dummy mirror onto the 150 active supports in the M1 cell. The cell with the mirror was then lifted by a handling device and placed on a low, heavy-load trailer.
Pulled by two heavy-duty trucks, the trailer was moved along the wide road to the top of the Paranal mountain and placed under another handling tool, just outside the UT1 enclosure. The cell was lifted and placed on a special carriage moving on air cushions.
This carriage was then moved into the telescope enclosure through the wide door foreseen for this and was positioned directly under the telescope tube. Then the cell was lifted and finally attached to the lower telescope struts. The carriage was removed from the building.
The M1 cell is now hanging free and is an incredible sight on the back of the telescope. According to one of the ESO engineers: It really makes the telescope look like a real astronomical machine!
In a next step, the secondary mirror (M2) and its mirror support (the M2 Unit) will be placed at the top of the telescope.
Later, the M1 cell with the concrete mirror will be removed and brought down to the MMB. Here the first 8.2-m Zerodur mirror - now coated with aluminium in the giant coating tank - will be put on the M1 cell and brought to the telescope. Soon thereafter, the UT1 First Light Event will take place.
In this connection, please note also the meeting for media representatives at the ESO Headquarters (Garching, Germany) on April 27 - 28, 1998.
More information about the Very Large Telescope (VLT) project is available on the ESO Web.