The European Extremely Large Telescope (E-ELT) will be the largest optical/near-infrared telescope in the world, boasting a primary mirror 39 m in diameter. Its aim is to measure the properties of the first stars and galaxies and to probe the nature of dark matter and dark energy, in addition to tracking down Earth-like planets.

At a ceremony in Garching bei München, Germany, on 25 May, the European Southern Observatory (ESO) signed a contract with the ACe Consortium for the construction of the dome and telescope structure of the E-ELT. With an approximate value of €400 million it is the largest contract ever awarded by ESO and the largest contract ever in ground-based astronomy. The occasion also saw the unveiling of the construction design of the E-ELT, which is due to enter operation in 2024.

The construction of the E-ELT dome and telescope structure can now commence, taking telescope engineering into new territory. The contract includes not only the enormous 85 m-diameter rotating dome, with a total mass of around 5000 tonnes, but also the telescope mounting and tube structure, with a total moving mass of more than 3000 tonnes. Both of these structures are by far the largest ever built for an optical/infrared telescope and dwarf all existing ones.

The E-ELT is being built on Cerro Armazones, a 3000 m-high peak about 20 km from ESO’s Paranal Observatory. The access road and leveling of the summit have already been completed and work on the dome is expected to start on site in 2017.