The ARRAKIHS mission will study dark matter in the universe, which is five times more abundant than ordinary matter according to cosmological observables
2 November 2022
The Science Programme Committee of the European Space Agency (ESA) has today officially approved the selection of the ARRAKIHS mission, the first ESA Science Programme mission to be led from Spain, in particular from the Institute of Physics of Cantabria (IFCA), a joint centre of the Spanish National Research Council (CSIC) and the University of Cantabria (UC), with the aim of launching it in 2030.
The team responsible for ARRAKIHS will be led by Rafael Guzmán, CSIC researcher, member of the Observational Cosmology and Instrumentation Group at IFCA and professor at the University of Florida, and a research group from the Complutense University of Madrid (UCM), the Instituto de Astrofísica de Andalucía (IAA-CSIC), the Instituto de Ciencias del Espacio (ICE-CSIC), the Centro de Astrobiología (CAB, INTA-CSIC) and the Centro de Estudios de Física del Cosmos de Aragón (CEFCA), in collaboration with the company Satlantis.
The ARRAKIHS mission (acronym for "Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys") was submitted to ESA's Fast Missions Opportunities programme in February this year, and an international consortium is participating in its development, with research centres from Spain, Switzerland, the United Kingdom, Belgium, Sweden, Austria and the United States, in response to the announcement published by ESA in December 2021. Subsequently, in August, it received support from the Spanish Ministry of Science and Innovation through its qualification in ESA's PRODEX programme, managed by the Centre for the Development of Industrial Technology (CDTI).
The main scientific objective of the mission is the study of dark matter in the universe, which according to different cosmological observables could be up to five times more abundant than ordinary matter. Because of its properties, its direct detection is very complex and, for now, we are only aware of its existence through its gravitational effects. It is precisely these effects on satellites orbiting in the halo of galaxies like our Milky Way that ARRAKIHS will be able to discover and characterise in order to reveal the nature of dark matter.
An astronomical milestone
For the mission, the company Satlantis has designed and developed a binocular visible and infrared camera that will make it possible to image one hundred galaxies similar to the Milky Way, reaching a surface brightness 5-100 times deeper than the best images taken from ground-based observatories. The depth, resolution and large field of the images provided by ARRAKIHS will be an astronomical milestone and will provide key information about the knowledge of dark matter in the Universe and its origin.
The Satlantis iSIM binocular camera will provide ultra-low surface brightness images of the Universe in four visible and infrared bands./Satlantis
Through these images, and using novel signal processing methodologies, it is expected to be able to determine whether the nature of dark matter, as suggested by other cosmological observations, is of the cold type, i.e. made up of particles moving at non-relativistic velocities (moving at speeds significantly smaller than light). This is a key aspect, because while the cold dark matter model seems to be the preferred model for large-scale cosmological observations, some of its properties on small scales, the size of galaxy halos, are in tension with current observations.
Thus, the sensitivity and ultra-low surface brightness expected from ARRAKIHS will allow the predictions of the cold dark matter model to be confirmed or disconfirmed on the scales of galaxy halos, and at unexplored surface brightness levels.
In addition, the IFCA will host the mission's data processing centre, which is key to obtaining the maximum possible knowledge of dark matter from the ARRAKIHS data.