Announcement

Contract Signed for ELT Primary Mirror Segment Supports

19 April 2018

ESO has signed a contract with VDL ETG Projects B.V. (the Netherlands) for the manufacture, assembly, testing and delivery of the Segment Support Mechanics for the primary mirror of ESO’s Extremely Large Telescope (ELT). The segment supports together act as the backbone of the primary mirror, holding each of the 798 mirror segments in place. Sensors and actuators monitor and control each segment’s shape and position to very high accuracy.

The contract was signed by Harrie Schonewille, Managing Director of VDL ETG Projects, Willem van der Leegte, President VDL and Xavier Barcons, Director General of ESO, at a ceremony at ESO Headquarters in Garching, Germany on 19 April 2018.

When completed, the ELT’s primary mirror (M1) will be 39 metres in diameter and will consist of 798 hexagonal mirror segments. The hexagonal shape means that a common support structure can be used for all segments. Each segment will be connected to the back-structure by means of a segment support system. This is composed of three linkage mechanisms that balance the forces applied and hold the segment via 27 axial actuators and one lateral actuator. The shape of each segment can also be optimised by means of warping harness actuators. Each segment, some 1.4 metres across and weighing 250 kilograms, will be mounted on three position actuators.

ELT first light is planned for 2024, when it will begin to tackle the biggest astronomical challenges of our time. The giant telescope is expected to allow the exploration of completely unknown realms of the Universe — it will be “the world’s biggest eye on the sky”.