Assembly is now underway on the main telescope of Euclid; the highest-performance optical instrument that Airbus has ever constructed
The Euclid mission aims to map the geometry of the “dark universe” – the regions which are too cold to emit visible light. Its telescope, the most complex that Airbus has ever designed and built, according to Philippe Pham, head of Earth observation, navigation and science at Airbus, is made entirely of silicon carbide, a technology which the company employed in the building of the telescope for Herschel, a spacecraft active between 2009 and 2013 and at the time, the largest infrared telescope ever built.
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“With the ultimate goal to understand the origin of the Universe’s accelerating expansion, Euclid will map the geometry of the dark universe with unprecedented accuracy,” said mission project manager Giuseppe Racca. The spacecraft, operating at temperatures of 100K, will collect a different high resolution image every 80 minutes for six years.
The module currently being constructed at Airbus Space and Defence’s facility in Toulouse has three primary features: the main telescope, a 1.2m diameter mirror and a three-mirror Korsch telescope, a type of instruments designed to be free from the optical aberrations incurred by telescopes with only one mirror. Korsch telescopes are capable of a wider field of view than single-mirror types and on Euclid, will supply light to two scientific instruments that will analyse the wavelengths and provide information about the composition of the objects it is observing. Like all space telescopes, its assembly requires extreme accuracy and clean conditions: the precision required for mechanical assembly is in microns, and for optical alignment in nanometres.
The Toulouse team is currently assembling the main telescope. After mounting the truss onto the base plate – both components being made of silicon carbide – Airbus engineers are now performing optical alignment. After this is complete, the module will be sent to the main contractor for the mission, Thales Alenia Space, in Italy for further testing and integration with the main platform of the Euclid spacecraft.
Euclid’s ultimate goal is to help cosmologists understand dark matter and dark energy: the mysterious substances not made of conventional atoms which are known to comprise 80 per cent of the universe but have not been detectable by any scientific instrument to date. It will do this by measuring the shapes and distances to galaxies and clusters of galaxies and the relationship between distance and the speed at which they are moving away from Earth, or rather the Lagrange 2 point of the sun-Earth system, and from each other.
The distances it will measure are so large that it is effectively looking 10 billion years back in time – the entire period during which it is believed that dark energy is believed to have had most of its influence on the expansion of the universe. Euclid is classified as a medium-class mission, and as such its cost is capped at €500m. It involves 16 countries, including the UK, Canada and the US, and is planned for launch in June 2022.