ELT primary mirror segments finished in France set for transport to Chile

At a plant in Saint-Benoît, a small town in the Poitou region, Safran Reosc has finished the last of the 931 hexagonal segments that will form the primary mirror of the Extremely Large Telescope. The factory, equipped with robotic and partially automated lines since 2020, tags each piece with an RFID chip to track production data. Polishing time has been cut dramatically, from two years per segment at launch to two months in 2024, allowing the team to produce and test a segment each day.

The finished segment will embark on a multi-modal journey—hundreds of kilometres by truck followed by thousands of kilometres by ship—to reach the summit of Cerro Armazones in Chile’s Atacama Desert. Once assembled, the 39-metre mirror will gather roughly twenty times more light than the Very Large Telescope, enhancing the ability to separate closely spaced celestial objects such as exoplanets from their host stars. The telescope’s dome, standing 80 metres tall, will dominate the landscape of the remote site.