The European Space Agency (ESA) mission, led by Spain, will provide key insights into the behavior of dark matter.
The ARRAKIHS space mission, selected by the European Space Agency (ESA) and led by Spain, has begun its scientific preparation phase at the Javalambre Astrophysical Observatory (OAJ) in the province of Teruel. This milestone marks a key step toward the mission’s scheduled launch in 2030, which will study the galaxy formation process—including the role of dark matter—in systems like the Milky Way.
A ground-based demonstrator, closely resembling the one to be launched into space, is already operating at the OAJ. This is an iSIM-170 binocular camera built by Spanish company Satlantis and acquired by the Institute of Physics of Cantabria (IFCA, CSIC-UC). The camera features two telescopes and a multiband imaging system capable of observing both in the visible and near-infrared spectra. It has been fully adapted for ground-based operations, enabling it to capture highly detailed images of observed galaxies.
One aspect is that the demonstrator’s performance will be tested using real data to determine if it meets the required image depth and quality. It will also allow for testing and validating observation strategies and data analysis procedures, optimizing these aspects of the mission before launch.
“Our goal is to be as prepared as possible for launch while reducing any uncertainties,” says Antonio Marín-Franch, lead researcher at the OAJ and a member of the ARRAKIHS Core Team. “This will allow us to conduct feasibility studies for some of the mission’s critical elements,” he adds.
A Mission to Explore the Invisible
ARRAKIHS (Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys) aims to deepen our understanding of dark matter and galaxy formation, with a particular focus on the Milky Way.
Over a three-year period, it will observe more than seventy nearby galaxies similar to our own, in visible and infrared light, using a mini-satellite in low Earth orbit (650–800 kilometers). This approach will overcome the challenge of capturing deep images with very low surface brightness from Earth, which is hindered by atmospheric interference.
“The investment made by IFCA in this demonstrator is a huge help for our work,” says Biuse Casaponsa, IFCA researcher and coordinator of the mission’s project office. “Being able to test the instrument under real-world conditions like those at the OAJ is crucial for proper preparation.”
Location: Javalambre Astrophysical Observatory
The observatory, one of seven Unique Scientific and Technical Infrastructures (ICTS) for astronomy in Spain, provides the site and mount where the ground demonstrator is already installed. Specifically, it is located in the so-called Monitors building, and the tests being carried out also involve the setup of support services, remote access, and connectivity. This milestone, part of the instrument’s critical review, is one of the main contributions of the Centro de Estudios de Física del Cosmos de Aragón (CEFCA)—the institution that manages the observatory—to the mission at this stage.
The experience of the personnel and their ability to lead and develop international projects are some of the strengths of the CEFCA teams. Combined with the exceptional sky conditions, they make the OAJ an ideal location to test the ARRAKIHS mission.
With the camera installed at Javalambre, more than one hundred hours of observation will be dedicated to each of the target galaxies, similar to the Milky Way. This will help validate the instrument, the scientific approach, and the data analysis tools. After the satellite is launched in 2030, the ground demonstrator will continue supporting the space-based instrument, enabling valuable comparisons between terrestrial and orbital data.
“The ground demonstrator is a rather unconventional feature for a space mission. Having Earth-based observations using the same space camera at this early stage gives us a major advantage for optimizing the scientific instrument,” says Santiago Serrano, ARRAKIHS Instrument Lead, Chief Science Officer at Satlantis, and researcher at the Institute of Space Studies of Catalonia (IEEC) and the Institute of Space Sciences (ICE-CSIC). “It was spectacular to see these stunning deep-space images for the first time with the iSIM-170 camera. It exceeded our expectations.”
More Research and Training
In addition to testing the ARRAKIHS observation strategy and camera performance, the demonstrator installed at Javalambre will also be used to conduct Earth-based science. In the future, it could become a small observatory dedicated to studying extremely faint galaxies, which are hard to detect with standard telescopes.
The project also includes an educational component: PhD students and amateur astronomers will be trained to operate the system remotely.
Participation of IFCA and Satlantis
IFCA (CSIC-UC) is the national institution leading the mission and purchased the camera, funded by the State Research Agency (AEI) and co-financed by the European Union under the State Programme to Address the Priorities of Our Environment, part of the 2021–2023 State Plan for Scientific and Technical Research and Innovation (PCI2023-143421).
On the other hand, Satlantis, a Spanish company, leads the industrial side of the ARRAKIHS Mission Consortium (AMC), which includes tech companies from across Europe. The consortium also includes universities and research centers with scientific and engineering personnel from various European countries, including Spain, Austria, Belgium, Portugal, Norway, the United Kingdom, Sweden, and Switzerland.
