MESSIER is a space mission designed specifically at exploring the last remaining niche in observational parameter space: the very low surface brightness universe

The mission will drift-scan the entire sky in six filters covering the 200-1000 nm range, reaching the unprecedented surface brightness levels of 34 (optical) and 37 (UV) mag arcsec-2. These levels are required to achieve the main science goals of the mission: to critically test the ΛCDM paradigm through (1) the study of ultra-faint galaxies; (2) tracing the cosmic web, and (3) setting up a fundamental and unambiguous test of galaxy formation.


Mission Concept

An all-sky mission optimized for exploring the low surface Universe

The payload consists of an off-axis TMA telescope with a 40 cm primary mirror at f/2 which produces an ultra-stable PSF with ultra-low wings across the 2ºx4º field-of-view. This unprecedented FoV is tiled using 12 independent 2k x 4k curved CCDs. The optimized design of the MESSIER single instrument ensures a factor 200x better efficiency than HST in terms of surface brightness detection. MESSIER’s payload fits very well in existing platforms (SSTL-150, CHEOPS or PROBA-V).




MESSIER will be able to understand galaxy formation processes at all scales and epochs

Two ΛCDM predictions remain untested. On highly non-linear scales, the abundance of dark sub-haloes is several orders of magnitude larger than the one of dwarf galaxies, while on large scales there should be a pattern of filaments (the cosmic web) containing a sizeable fraction of the low redshift baryons.



A project led by European and international institutions

Designed for New Science

Complete Inventory of Galaxies, the Baryonic Cosmic Web, from Zodiacal Light to the Cosmological background

The First All-Sky Optical-UV LSB Survey 

A Unique Legacy Archive for the Astronomy Community with 100s of Millions of Stars and Galaxies

Low-Risk Implementation as a Small/Fast mission

Single Observing Mode, no moving parts, passive cooling