Manufacturing of the 949 segments of the ELT supermirror concludes

June 27 () –

The last of the 949 segments of the Extremely Large Telescope (ELT) primary mirror (M1), which is being built in the Chilean Atacama Desert, It has been manufactured in Germany.

With a diameter of more than 39 meters, M1 will be the largest mirror ever built for a telescope. Because it is too large to be a single piece of glass, the primary mirror, M1, will be composed of 798 hexagonal segments, each about five centimeters thick and 1.5 meters wide, which will work together to collect tens of millions of times more light than the human eye.

An additional 133 segments have been manufactured to facilitate maintenance and coating of the segments once the telescope is operational. ESO (European Southern Observatory), operator of the telescope, has also purchased 18 spare segments, which brings the total number to 949.

The M1 blanks (pieces of material that are shaped and then polished into mirror segments) are made of Zerodur, a low-expansion glass-ceramic material developed by the Schott company and optimized for the extreme temperature ranges that occur at the ELT location, in the Chilean Atacama Desert. This company has also manufactured the blanks for three other ELT mirrors (M2, M3 and M4) at its facilities in Mainz, Germany. In total, 230 tons of this special material have been produced.

Once polished and assembled, each M1 segment is shipped across the ocean to reach the ELT technical facilities at ESO’s Paranal Observatory in the Atacama Desert, a 10,000 kilometer journey that has already seen more than 70 segments completed. M1. In Paranal, a few kilometers from the ELT construction site, each segment is covered with a layer of silver to become reflective, after which it will be carefully stored until the main structure of the telescope is ready to receive them.

When it begins operations later this decade, ESO’s ELT will be the world’s largest eye to the sky. It will address the greatest astronomical challenges of our time and make discoveries still unimaginable, according to a statement from the ESO.