The European Space Agency’s (ESA) Science Programme Committee has adopted the Arrakihs mission, clearing it to move from study into development. ESA stated the spacecraft is planned for launch by the end of 2030 and will be designed to capture extremely faint light from nearby galaxy haloes to study how galaxies form and evolve.
Key Details
- Adoption indicates the study phase is complete, the mission has been shown to be feasible, and ESA is committing to implement it.
- The next stage involves building, integrating, and extensively testing the spacecraft and its scientific instrumentation.
- Arrakihs is the second “fast” (F-class) mission in ESA’s Cosmic Vision programme, intended to take less than 10 years from selection to launch.
- The decision was taken during the Science Programme Committee meeting at the Instituto Astrofísico de Canarias in Tenerife on 10–11 June 2026.
Mission Objectives
- Focus on galaxy haloes—large, faint regions surrounding galactic discs that contain mostly invisible dark matter as well as stars and hot, charged gas.
- Observe diffuse stellar haloes and structures such as stellar streams, described as remnants of smaller galaxies disrupted by gravity.
- By mapping stellar streams, Arrakihs aims to help reconstruct the history of past galaxy mergers and estimate the number of stars stripped during those events.
- Investigate at least 80 galaxies with similar mass to the Milky Way to provide statistical insight into galaxy formation and whether the Milky Way is unusual.
Instrumentation
- Carry a single scientific instrument made up of two pairs of “binocular telescopes,” for a total of four cameras.
- Each camera will cover a different wavelength band, from near-ultraviolet through visible light into near-infrared.
Professor Carole Mundell, ESA’s Director of Science, described Arrakihs as a ground-breaking and unique galactic archaeology mission that will reveal new details of how galaxies form and whether the Milky Way galaxy is unique. She noted its rapid development showcases the flexibility and breadth of ESA’s Science Programme.
Background
- The mission name is an acronym for Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys.
- The instrument is being designed and developed by a consortium of ESA Member States led by Spain, with Switzerland, Austria, Belgium, Norway, Portugal and Sweden as core partners. Many contributions are supported through ESA's Prodex programme.
- Arrakihs will join ESA’s fleet of “Cosmic Observers,” aligned to the Cosmic Vision 2015–2025 science themes, including questions about fundamental physical laws and the Universe's origins and composition.