The European Extremely Large Telescope (E-ELT) will be a ground-based astronomical observatory with a 42-meter diameter segmented mirror. The design features a filled aperture mirror with an area of 1,300 m². On 26 April 2010, the European Southern Observatory (ESO) Council selected Cerro Armazones, Chile, as the baseline site for the planned E-ELT. The telescope's "eye" will be almost half the length of a soccer pitch in diameter and will gather 15 times more light than the largest optical telescopes operating today. The telescope has an innovative five-mirror design that includes advanced adaptive optics to correct for the turbulent atmosphere, giving exceptional image quality. The main mirror will be made up from almost 1000 hexagonal segments. If completed it will become the largest of a new generation of Extremely Large Telescopes.
The ESO is focusing on this design after a feasibility study concluded the proposed 100 metres (330 ft) diameter Overwhelmingly Large Telescope would cost €1.5 billion (£1 billion), and be too complex. Current fabrication technology limits single mirrors to being roughly 8 metres (26 ft) in a single piece. The next-largest telescopes currently in use are the Gran Telescopio Canarias and Southern African Large Telescope, which each use hexagonal mirrors fitted together to make a mirror more than 10 metres (33 ft) across. The E-ELT would need to use a similar design. In addition, the E-ELT would also need to use techniques to work around atmospheric distortion of incoming light, known as adaptive optics (AO).
Project E-ELT has the aim of observing the Universe in greater detail than even the Hubble Space Telescope. A mirror of approximately 42 metres (138 ft) would allow the study of the atmospheres of extrasolar planets. The E-ELT is now planned in the Astronet Infrastructure Roadmap, and “is currently going through a Phase B study that will end with a Final Design Review of the whole facility in 2009/2010. This Phase B study includes contracts with industry to design and manufacture prototypes of key elements like the primary mirror segments, the adaptive fourth mirror or the mechanical structure. It also includes concept studies for eight instruments.”
Because of the competition with some similar projects (in particular the Thirty Meter Telescope and the Giant Magellan Telescope), “the decision for the construction of the European ELT cannot be deferred later than 2010.” The construction period is estimated to be 7–8 years leading to first light around 2018. The design phase of the 5-mirror anastigmat (€57M) is fully funded within the ESO budget, and the construction cost is estimated to be €960M (including first generation instruments). “About €350M for the construction phase are available within the existing budget integrated over a period of ten years. One of the goals of the preparatory phase is to study the possibilities for additional funding. Additional activities on the organisation of the project and the mission design are supported through a €5M FP7 grant.”
Eight different instrument concepts and two post-focal AO modules are currently being studied, with the aim that two to three will be ready for first light, with the others becoming available at various points over the following decade. The instruments being studied are:
The two post-focal AO modules currently being studied are:
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Categories: Telescopes | Astronomical observatories in Chile | European Southern Observatory