The European Space Agency (ESA) has officially adopted Arrakihs, a new space mission dedicated to galactic archaeology. Named for 'Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys', Arrakihs will study the faint outer haloes of galaxies to uncover their formation history. Scheduled for launch by the end of 2030, it marks the second 'fast' mission in ESA’s Cosmic Vision programme, moving from selection to launch in under a decade.

Galaxy haloes, made mostly of dark matter and sparse stars, hold clues to how galaxies grow by merging over time. Current models are limited by a lack of observations of these faint structures. Arrakihs will observe at least 80 galaxies similar in mass to the Milky Way, mapping stellar streams—remnants of smaller galaxies torn apart by gravity. This will help scientists understand whether our galaxy is typical or unusual in the cosmos.

The mission carries a single instrument composed of two 'binocular' telescopes, totaling four cameras sensitive to wavelengths from near-ultraviolet to near-infrared. Led by a consortium of ESA member states including Spain, Switzerland, and Sweden, the instrument benefits from contributions coordinated through ESA’s Prodex programme. Once operational, Arrakihs will join ESA’s fleet of cosmic observatories probing fundamental questions about the Universe’s origin and structure.