Last generation of large telescopes faces several technical challenges in terms of design, manufacturing, and operation, but also in terms of assembly and maintenance. A new generation of multipurpose devices are required to access M1 to make regular and repetitive alignment, cleaning, and mirror manipulation activities in a reliable and productive way.

The Segment Exchange Manipulator, which is being developed for the ESO ELT operations, is the first generation of a multipurpose device for telescopes M1 assembly and maintenance operations. Its architecture and modularity make it possible to perform many different operations occurring on M1: structures handing for assembly operations and different maintenance operations, like handling, alignment measurement, cleaning (i.e., new laser cleaning devices), dust deposition measurement, among other potential applications.

The main architecture consists of a hoist for general purpose loads transfer, and a 6 DoF positioning, which attaches to the hoist subsystem, capable to accurately position loads on M1 curved surface. The positioning subsystem integrates a fast-attaching mechanism to rapidly fix different loads (including segment assemblies), a complete sensing system for telescope and mirror collision prevention, as well as an advance image acquisition and processing system capable of accurately positioning the load with respect to specific targets. The positioning can supply power and network communications to perform any required operation.

The current solution has been designed to handle passively and safely ELT M1 Segments, even under extreme earthquake conditions and can be adapted and scaled to different requirements in terms of positioning range, weight, and specific capabilities.