A unique instrument for the biggest telescope


The Extremely Large Telescope (ELT), i.e., ESO's future 39 meter telescope, will probably be the most ambitious ground-based optical astronomical facility of the century. Its main scientific objectives are the detection and study of the formation of the very first structures in the early Universe, 10-13 billion years ago, and obtaining the very first images of super exo-Earths and more generally the systematic characterization of extrasolar planets and their formation process.

The ELT is particularly innovative since it proposes for the first time to integrate the concept of adaptive optics directly within the telescope (Ground Layer Adaptive Optics, GLAO), which will provide uniform image quality and reduce the dependence of the observations to atmospheric conditions. Its great collecting power will reach sensitivities unmatched by any competing american ELT project. It will provide european astronomers with the most ambitious optical astronomical observation tool and the most powerful telescope ever built.

A fundamental prediction of cosmological models is that structures evolved "hierarchically" by successive mergers of more and more massive objects from the Big Bang to the galaxies we see around us today. Questions such as what seeded the growth of the first primordial galaxies and the history of galaxies like our own Milky Way remain unclear - only the ELT can bring the answers within our reach.

A major challenge is awaiting astronomers: the Universe contains hundreds of billions of galaxies, each of which consists of hundreds of billions of stars! Surveying these systems efficiently calls for a multi-object spectrograph (MOS) know as ELT-MOS as soon as possible after first light of the ELT in 2024.

The international MOSAIC Consortium is gathering together efforts across Europe and beyond to build this ELT survey machine. It includes major players in instrument development and conception, which built a number of effective and scientifically productive instruments for the VLT (FLAMES, KMOS, NACO, X-SHOOTER).

The most prominent objective of MOSAIC will be to conduct the first exhaustive inventory of matter in the distant Universe. This will lift the veil on how matter is distributed in and between distant galaxies, by accounting for all kinds of regular matter, comprising stars and different phases of gas, as well as so-called dark matter.

The MOSAIC design has also been driven by 6 core science cases (below), but with its design also strongly influenced by other cases developed by the community in the MOS White Paper to ensure we are as ready as possible for the exciting discoveries awaiting in the late 2020s.

MOSAIC will give a tremendous leap forward in our understanding of how present-day galaxies formed and evolved. This includes detecting nearby primordial stars, the very first galaxies at the epoch of re-ionization, the most exhaustive dynamical survey of distant galaxies ever undertaken, and detailed study of stars in galaxies millions of light years beyond the Milky Way.


 Click here to list the MOSAIC science team.