Symmétrie was chosen to supply the positioners for the sub-reflectors of the twelve antennas of the Noema telescope at Pic de Bure in the Hautes Alpes.
Developed and operated by IRAM, the Institute for Millimeter Radio Astronomy, Noema will be the most powerful millimeter radio telescope in the northern hemisphere, thanks to the addition of six new antennas, bringing the total number of antennas from six to twelve. The sub-reflector is the equivalent of a secondary mirror on an optical telescope, and will reflect the millimeter waves collected by the primary reflector back to the instrument, which will then analyze the images obtained to study the origins and evolution of the Universe.
In collaboration with Iram, Symmetry designed a specific system based on the standard Breva hexapod, with these main objectives in mind: reliability in a high-mountain environment, mechanical performance, light weight, easy maintenance and controlled costs.
The main features of this hexapod are its long strokes, carbon fiber composite platforms and the thermally optimized design of the sub-reflector-support assembly. A specific thermomechanical decoupling device made from Invar provides a significant improvement in deformation under thermal stress. Invar is an iron-nickel alloy known for its very low coefficient of thermal expansion of 1 µm/m/°C.
As a first step, Symmetry produced an initial hexapod, which underwent accelerated ageing tests in a climatic chamber, as well as a complete winter at the top of the Bure plateau to assess the resistance of the system and its components to particularly harsh environmental conditions.
Following conclusive tests on the first hexapod, Iram has decided to equip the rest of the new antennas as well as the old ones on the basis of the hexapod model tested. Twelve Symmetry hexapods will be installed on Noema by 2022.
Learn more: www.symetrie.fr
