Active mirror supports in VLT M1 cell

The primary mirrors (M1) of the four Unit Telescopes weigh 22 tonnes, measure 8.2 m across and are only 17 cm thick. Each of them rests on 150 computer-controlled supports that are installed in an exceedingly rigid M1 Cell that weighs about 11 tonnes. The supports are an integral part of the VLT Active Optics system which ensures that the large mirrors always have the optimal shape.