More than half of the Extremely Large Telescope's mirror segments have reached Chile

28 October 2026

The European Southern Observatory says nearly 500 of the 931 segments made for the main mirror, M1, of the Extremely Large Telescope have now arrived in Chile, more than half the total produced. M1 itself uses 798 segments; the other 133 are spares, so a segment can be taken out for recoating without leaving a gap in the mirror. The segments are received, inspected and coated at the ELT Technical Facility at ESO's Paranal Observatory, and the telescope is being built on Cerro Armazones nearby. ESO describes the ELT as a 39-metre eye on the sky. SCHOTT in Germany made the glass-ceramic blanks and Safran Reosc in France figures, polishes and mounts the segments. The project is more than 75 per cent complete and the first observations with science instruments are planned for late 2030.