Preliminary design for an enclosure for the European Extremely Large Telescope

The baseline design for the enclosure of the E-ELT is based on a spherical dome concept. This dome is tightly fitted to the TRV so that its surface, the enclosed volume and consequently the system overall cost are minimized. The large slit that is required for observation-as compared to the enclosure volume-, much larger than in smaller telescopes, poses a big challenge to the design. This affects the slit covering system design, for which dynamic issues must be carefully considered in order to prevent operation problems, as well as the dome structure and other mechanisms such as the windscreen and the crane, that have to cover a large 45m span. This paper presents a design that solves all these difficulties in both a cost-effective and reliable way. The design work presented in this paper has been performed under contract with the European Southern Observatory.