Segun la web del mismo... un espejo de 40 metros!!!! madre mia!!!
E-ELT
Name: European Extremely Large Telescope
Site: Cerro Armazones
Altitude: 3060 m
Enclosure: Hemispherical dome
Type: Optical/near-infrared Giant Segmented Mirror Telescope
Optical design: Five-mirror design — three-mirror on-axis anastigmat + two fold mirrors used for adaptive optics
Diameter. Primary M1: 39.30 m (798 hexagonal 1.4 m mirror segments)
Material. Primary M1: Not decided yet
Diameter. Secondary M2: 4 m
Material. Secondary M2: Not yet known
Diameter. Tertiary M3: 3.75 m
Mount: Alt-Azimuth mount
First Light date: Early 2020s
Active Optics: Yes
Adaptive Optics: 2.60 m adaptive M4 using 6 Laser Guide Stars
http://www.eso.org/public/spain/news/eso1225/