\tScience & Exploration<\/p>\n
\t\t\t\t\t\t10\/06\/2026
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The European Space Agency\u2019s (ESA) Science Programme Committee has adopted the Arrakihs<\/a> mission. Planned for launch by the end of 2030, Arrakihs will capture the faint light from nearby galaxy haloes. By seeing the unseen, Arrakihs will dig up cosmic history and reveal how galaxies like our own form and evolve.\u00a0\u00a0<\/p>\n Being adopted means that the study phase is complete, the mission is shown to be feasible, and ESA commits to implementing it. In the upcoming development phase, the spacecraft and its scientific instrumentation will be built, integrated and extensively tested.\u00a0\u00a0<\/p>\n Arrakihs is the second \u2018fast\u2019 or F-class mission of ESA\u2019s Cosmic Vision<\/a> programme, needing less than ten years from its selection in November 2022 until launch. The decision to adopt it was made at the Science Programme Committee meeting at the Instituto Astrof\u00edsico de Canarias, Tenerife (10\u201311 June 2026).\u00a0<\/p>\n \u201cArrakihs is a ground-breaking and unique galactic archaeology mission. By uncovering hard-to-see galaxy haloes, it will reveal new details of how galaxies form and whether the Milky Way galaxy is unique. Its rapid development showcases the flexibility and breadth of ESA\u2019s Science Programme,\u201d says Professor\u00a0Carole Mundell<\/a>, ESA\u2019s Director of Science.\u00a0<\/p>\n The mission name stands for Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys.<\/p>\n \t\t\t\t\t\t\tSimulated galaxy haloes<\/a><\/p>\n \t\tUncovering galactic history\u00a0<\/p>\n Picture a galaxy. You might imagine a glowing, spiralling disc of stars, gas and dust. What you probably don\u2019t picture is the much larger ball-shaped region surrounding this disc, filled with matter that is much harder to see.\u00a0<\/p>\n This region, called the galaxy halo, is mostly made up of invisible dark matter<\/a> acting as the galaxy\u2019s gravitational glue. The rest of the halo consists of normal matter, including stars and hot, charged gas. Arrakihs will observe diffuse stellar haloes and structures such as stellar streams<\/a> \u2013 remnants of small galaxies that were torn apart by gravity.\u00a0<\/p>\n Importantly, a galaxy\u2019s halo contains clear traces of how the galaxy formed and evolved over cosmic time. Scientists believe that galaxies grow over time by merging with others. Because galaxy haloes are so faint, we haven\u2019t been able to study enough of them to be sure that our models of galaxy formation \u2013 and by extension the role of dark matter \u2013 are correct.\u00a0\u00a0<\/p>\n By mapping stellar streams, Arrakihs will allow us to piece together the history of past mergers and give an estimate of the number of \u2018lonely\u2019 stars that were ripped away from their galaxies during mergers.\u00a0<\/p>\n In total, Arrakihs plans to investigate at least 80 galaxies with a similar mass to the Milky Way galaxy. This is a large enough number to get statistics on how a \u2018typical\u2019 galaxy forms, allowing us to understand how unique our home galaxy is.<\/p>\n \tTwo pairs of European eyes <\/p>\n \t\t\t\t\t\t\tWorking on one of Arrakihs’s binoculars<\/a><\/p>\n The mission needs to detect extremely faint objects with a \u2018low surface brightness\u2019. To do this, Arrakihs will carry one scientific instrument consisting of two pairs of \u2018binocular telescopes\u2019, a total of four cameras. Each camera is sensitive to a different band of wavelengths, spanning from the near-ultraviolet, through the visible spectrum, into the near-infrared.\u00a0\u00a0<\/p>\n The instrument is being designed and developed by a consortium of ESA Member States led by Spain. Other core consortium partners are Switzerland, Austria, Belgium, Norway, Portugal and Sweden. Many of the instrument contributions are supported through ESA’s Prodex<\/a> programme.\u00a0<\/p>\n Arrakihs will join ESA\u2019s fleet of Cosmic Observers<\/a>. These missions primarily address two top-level science themes of ESA\u2019s\u202fCosmic Vision 2015\u20132025<\/a>, namely: What are the fundamental physical laws of the Universe?\u202fand\u202fHow did the Universe originate and what is it made of?\u00a0<\/p>\n