Announcement

First segments of ELT’s main mirror arrive in Chile

16 January 2024

After a 10 000 km journey across the world, the first mirror segments of ESO’s Extremely Large Telescope (ELT) have safely arrived in their next home, the ELT Technical Facility at ESO’s Paranal Observatory in the Chilean Atacama Desert. A total of 18 segments (out of 798) of the telescope’s main mirror (M1) successfully made the trip from Europe to South America, first arriving in Chile at the Antofagasta Terminal International (ATI) port last week.

Once complete, the ELT’s M1 will be over 39 metres across, making it the world’s largest eye on the sky. Such scale means that the mirror can’t be cast in one piece, thus, 798 hexagonal segments will work together to form M1. An additional 133 will be produced to facilitate the segments’ recoating.

Embarking on a remarkable voyage that began near Poitiers, France, where the ELT segments were finished, they then traveled by road to the port of Le Havre. On 17 December 2023, these vital components of the ELT set off across the ocean. They arrived at the port of Antofagasta and continued their long journey on dry land, reaching ESO’s Paranal Observatory on 12 January 2024. There, ESO engineers performed extensive inspections to confirm they did not suffer any damage during transport.

With the segments at Paranal, the next phase in this intricate process involves the coating of the mirror segments in the ELT Technical Facility to give them their highly reflective finish, a process that will be reiterated on each segment every 18 months once the ELT begins observations. This monumental telescope, once operational later this decade, is poised to tackle the most profound astronomical challenges of our time, promising groundbreaking discoveries that were once unimaginable.