Consolidating the French participation to MOSAIC for the Extremely Large Telescope – MOSAIC-FR

This proposal is intended to consolidate the French participation to the development of MOSAIC, the future multi-object fiber spectrograph for the European Southern Observatory (ESO) 39m Extremely Large Telescope (ELT). It is a first generation instrument, with unique capabilities in terms of multiplex, wavelength coverage and spectral resolution. It has been optimized to achieve the best possible signal-to-noise ratio on the faintest sources, from very faint stars in our Galaxy to distant galaxies at the epoch of the reionization. MOSAIC is designed to cover the largest possible area of the ELT focal plane (~40 arcmin²) thanks to an original stepped and tiled focal plane design which allows parallel observations in different modes.

MOSAIC is the only ELT instrument with a French PI. The project has received support at the highest priority level since 2016. It has entered its B1 Phase in 2023, and the management structure has been consolidated both at the French and international levels. With the beginning of Phase B, the resources available at the Consortium level and the responsibilities of the different Work Packages have been reviewed. The Technological Readiness Level of several sub-systems must be pushed to reach a mature enough level of development and unlock the next development phases. This project intends to conduct the main developments under French responsibility that still need additional funding to be completed: i) the development of a NIR camera prototype for the NIR-spectrograph, ii) the industrialization of the construction of a huge number for fiber-bundles, iii) the design of the final version of the optical relays, and iv) the prototyping of a remote control system for the integration of the different MOSAIC channels. The aim is to guarantee a successful participation to MOSAIC of the French laboratories, namely LAM (Marseille), GEPI (Paris), IRAP (Toulouse) and LAGRANGE (Nice).