An Enclosure for the European Extremely Large Telescope

In the last decades of the XXth century the development of new technologies such as the thin monolithic meniscus mirrors with active optics, the segmented mirrors and the adaptive optics broke the limitations in the feasible diameter for the primary mirror and caused the origin of the 8–10m class telescopes. Considering the successful operation of 8–10m class telescopes in operation as the KECKs and the VLTs, both the American Community and the European Community began to prepare the next generation of telescopes, the Extremely Large Telescopes. Within the American-Australian Community two projects are currently being developed: the TMT (Thirty Meters Telescope), a 30m segmented mirror telescope developed by USA and Canada, and the GMT (Giant Magellan Telescope), a 24.5 meter aperture multi mirror telescope developed by USA and Australia. In Europe, the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) launched in December 2006 the Detailed Study of the European Extremely Large Telescope (E-ELT). The E-ELT is a 42m segmented primary mirror telescope with a five mirrors optical configuration. With respect to its enclosure, after some preliminary studies of different alternatives, a non co-rotating spherical dome configuration was selected.