The European Extremely Large Telescope (E-ELT) is a planned ground-based extremely large telescope for the optical/near-infrared range, to be built by the European Southern Observatory (ESO) on a mountain top in Cerro Armazones, Chile. The design comprises a reflecting telescope with a 39.3 metre diameter primary mirror, a 4.2 m diameter secondary mirror, and will be supported by adaptive optics and multiple instruments. On 11 June 2012, the ESO Council approved The E-ELT programme to begin construction of the telescope, pending agreement with the governments of some member states.
It is expected to allow astronomers to probe the earliest stages of the formation of planetary systems and to detect water and organic molecules in proto-planetary discs around stars in the making.
On 26 April 2012, the European Southern Observatory (ESO) Council selected Cerro Armazones, Chile, as the baseline site for the planned E-ELT. Other sites that were under discussion included Cerro Macon, Salta, in Argentina; Roque de los Muchachos Observatory, on the Canary Islands; and sites in South Africa, Morocco, and Antarctica.
Early designs included a filled single aperture mirror with a diameter of 42 metres and area of about 1300 m2, with a secondary mirror with a diameter of 5.9 m. However, in 2011 a proposal was put forward to reduce its size by 13% to 978 m2, for a 39.3 m diameter primary mirror and a 4.2 m diameter secondary mirror. It reduced projected costs from 1.275 billion to 1.055 billion euros and should allow the telescope to be finished sooner.
ESO’s Director General commented in a 2011 press release that “With the new E-ELT design we can still satisfy the bold science goals and also ensure that the construction can be completed in only 10-11 years.” The ESO Council endorsed the revised baseline design in June 2011 and expected a construction proposal for approval in December 2011. Funding was subsequently included in the 2012 budget for initial work to begin in early 2012. The project received preliminary approval in June 2012, with some funding details still needing to be worked out.
The E-ELT will complete its detailed-design phase by the end of 2011 and its construction is planned for 2012. The design phase of the 5-mirror anastigmat is fully funded within the ESO budget. With the recent changes in the baseline design (such as a reduction in the size of the primary mirror from 42m to 39.3m), the construction cost is estimated to be €1055M (including first generation instruments). The start of operations is planned for the early 2020s