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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| ARRAKIHS | 1/2 | https://en.wikipedia.org/wiki/ARRAKIHS | reference | science, encyclopedia | 2026-05-05T12:43:29.657368+00:00 | kb-cron |
ARRAKIHS (Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys) is a planned European Space Agency (ESA) space mission designed to study dark matter and galaxy formation by observing low-surface-brightness structures in the halos of nearby galaxies. Selected in November 2022 as an ESA F-class mission, ARRAKIHS is currently in its definition phase, with a projected launch in 2030. The mission aims to test the Λ-Cold Dark Matter (ΛCDM) model by analysing discrepancies between theoretical predictions and observations of small-scale structures, such as tidal stellar streams and dwarf satellite galaxies. To achieve this, ARRAKIHS will observe the local universe at very low surface brightness levels never before reached in visible and infrared wavelengths, using an innovative binocular telescope system designed specifically to capture ultra-low surface brightness images. The instrument will be launched on a mini-satellite that will orbit the Earth at an altitude of 800 km.
== Name == The mission is named after the planet Arrakis from science fiction novel Dune. The name is a backronym of "Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys".
== Objectives == ARRAKIHS was proposed by an international consortium of scientists to address the reported tensions between the ΛCDM model, baryonic physics (BP), and ground-based observations of small-scale structures (satellites and stellar streams) in the local universe. The mission objective is to compare three key halo properties with current models: the identification and measurement of tidal stellar structures in halos, the structure and luminosity profiles of galaxy stellar halos, and the mass functions of dwarf galaxy satellites. Many of these dwarf galaxies are expected to show signs of disruption, forming diffuse tidal structures as they are accreted by their host galaxy. These structures will contribute to intra-halo light, creating first stellar streams and then, after total disruption, contributing to the faint, extended halo around galaxies. The mission will offer a statistically significant sample of observables to evaluate whether discrepancies in the ΛCDM model are caused by selection biases or small sample sizes. If these tensions are confirmed, the mission will highlight inconsistencies in current galaxy formation models and may necessitate revisions or the exploration of alternative frameworks to explain the observed data more accurately.
== Mission profile == The telescope will be integrated into a small satellite platform with a total mass of approximately 600 kg. Operating in a sun-synchronous low Earth orbit (LEO) at an altitude of 800 km, for which the spacecraft is designed with specialized baffling and thermal control systems to minimize stray light and thermal noise, ensuring stable observational conditions. ARRAKIHS is planned to conduct a three-year survey, imaging roughly 100 square degrees of the sky observing approximately 75 Milky Way-type galaxy halos. The mission will have two operation modes: survey mode, where it will observe the sample galaxies for the ARRAKIHS science goals and the calibration mode. In the survey mode, each of these targets will be observed simultaneously in 4 bands for a total of 150h, with 900 exposures of 10 minutes each at different times. In the calibration mode, 7% of the observing time will be scheduled for calibration tasks including bias and pseudo-dark exposures, observation of flat-fielding correction, astrometric and photometric calibration, routine monitoring of the PSF and detector pixel operability.
== Instruments == The ARRAKIHS mission's primary payload is a dual binocular telescope system with a modified Maksutov Cassegrain design equipped with two visible-wavelength and two infrared cameras, optimized for low surface brightness astronomy. Developed by the Spanish aerospace company Satlantis, the prime contractor for the instrument's design and manufacturing, the system is designed to detect extremely faint stellar structures surrounding galaxies with high sensitivity and precision. The binocular telescope system features:
Telescope & Camera Module: Includes opto-mechanical assemblies, straylight baffles, instrument structure, focal plane assemblies with Visible CMOS sensors and H2RG detectors, and passive/active thermal control. Also includes the Straylight Baffle Assembly that rejects light outside the field of view such as bright stars and earth shine. Electronics Box: Houses control and data processing units, thermal regulation systems, and power distribution. Filters:
VIS filters, operating at visible wavelengths (VIS1: 280-420nm , VIS2: 381-863 nm), 2x Te2v CIS304 detectors. NIR filters, operating at near-infrared wavelengths (NIR 1: 857-1255nm , NIR2: 1168-1567 nm), 2x Teledyne H2RG detectors.
== Ground segment == The ground segment of a space mission encompasses all Earth-based infrastructure required for spacecraft operations, data reception, processing, archiving, and distribution. It consists of several key components, including ground stations that facilitate communication with the spacecraft and a mission control center responsible for its management. In the case of the ARRAKIHS mission, the ground segment also includes the computational infrastructure necessary to process raw data, specialized software for generating and archiving scientific images, and calibration tools to periodically adjust the onboard instruments. These elements ensure the mission's efficient operation and data dissemination. The responsaibility of the structural and scientific components of the ARRAKIHS Ground Segment is distributed between ESA and the ARRAKIHS Mission Consortium. The Science Ground Segment (SGS) is managed by ESA and includes ESA tracking facilities, the Mission Operation Center (MOC), the Science Operations Center (SOC), and the long-term archive of the mission: