Tekniker installs Nasmyth rotators in the Canary Islands Great Telescope

The telescope is located at almost 3,000 metres altitude, in the Roque de los Muchachos of La Palma island. The installation involved highly delicate manoeuvres, given the great size and weight of the structures being handled as well as the complexity and vulnerability of its structure and instrumentation.

The procedure was to lift the rotators, hoisting them on to the platform, fit them into their definitive position and align them with the optical axes of the telescope.

The Canary Islands Great Telescope is located in one of the three best places on the planet for quality of astronomic observations, due to their clear skies. Its primary mirror is made up of a mosaic of 36 hexagonal vitroceramic elements that fit together in such a way that it they form a surface area equivalent to that of a 10.4 m diameter mirror that is parabolic and has a circular perimeter. Thus, next year when it is inaugurated, the “Grantecan” will be the telescope with the largest segmented primary mirror in the world.

The Nasmyth rotators developed by Tekniker are two twinned systems, fitted either side of the main structure of the telescope, the aim of which being to move and position the instrument with precision in response to movements of stars. In mechanical terms, the Nasmyth rotators of the GTC telescope are made up of a main support structure and a mobile structure of two bearings, the first being a reference and anchor for the various instruments integrated in the installation, the second bearing on which the capture and guidance system of the telescope is supported. Both structures are united by means of a a set of roll cross bearings that enable a very high level of smoothness of rotation while providing high rigidity to the structure. The operation of the rotators is carried out by direct actuators based on synchronous linear motors. These motors are made up of 20 independent stators inserted in the fixed support structure and a rotor of permanent magnets located on the mobile structure. The measurement of the angular position, which is, at the same time, a feedback system for the links between speed and position, is undertaken by means of a encoded tape fixed to the mobile structure and six reader heads inserted in the fixed structure. The mobile structure itself carries out, moreover, the rotation of the cables and conductors that are necessary for both the instruments of observation and the system of capture and guidance system of the telescope.

This venture places Tekniker amongst the select few suppliers of mecatronics who are able to take on projects of this level of exigency and risk. All of this has been made possible by the proven capacity of Tekniker in technologies such as the magnetic positioning and displacement, control, precision and metrology of large structures.

Over the next few months and when all the various activities around the Great Telescope of the Canaries allow, our technical personnel will put their final touches to the work, the fitting and plaiting of the cables and placing them in a drag chain and the final acceptance trials before putting the rotators into operation. After a few more months, humanity will have a great new eye open to the Universe and its correct functioning will be in part due to Basque technology.