Rebecka Wahlén

• Retselis, Anastasios-Faidon; Knutsen, Elise Wright; Holdcroft, Sam; Viet, Shayla; Wahlén, Rebecka & Virdis, Mario [Show all 19 contributors for this article] (2026). CENSSAT-1: A space weather mission and an educational platform. In Detrell, Gisela; Alarcia, Ramón María García; Messina, Vincenzo & Kinnaird, Alexander (Ed.), Proceedings of the 5th Symposium on Space Educational Activities (SSEA). Technical University of Munich. p. 852–857. doi: 10.14459/2026MD1857465. Full text in Research Archive Show summary

  The Symposium on Space Educational Activities (SSEA), organised by the European Space Agency’s Education Office, provides a forum for university students, professionals working in education, and other professionals in industry or agencies to present and discuss their experiences organising, running and/or participating in Educational Activities related to Space. After successful past events in Padova (2015), Budapest (2018), Leicester (2019), and Barcelona (2022), the 5th SSEA was held in April 2026 (the 8th, 9th, and 10th) in the TUM Aerospace Campus in Willy-Messerschmitt-Strasse 5, Taufkirchen, Germany. The local organisation team was led by the Technical University of Munich (TUM), involving Professors, PostDocs, PhD Candidates, and Master’s and Bachelor’s students, in close collaboration with the Bavarian aerospace ecosystem partners.

• Kohfeldt, Anja; Wahlén, Rebecka; Jebali, Ramsey Al & Teodoro, Luis Filipe Alves (2024). A Hybrid Gamma-Ray and Neutron Detector for In-Situ Resource Utilization. Proceedings of the International Astronautical Congress. ISSN 0074-1795. p. 962–967. doi: 10.52202/078357-0109. Full text in Research Archive Show summary

  Gamma-ray spectroscopy, as well as neutron detection (GRND) are powerful tools for mapping available resources both remotely and in-situ. GRND allows us to characterize the abundance of hydrogen and elemental composition of the top meter of airless celestial bodies , or asteroids. Compact instruments can be deployed on orbiters, landers or rovers for either mapping larger areas or narrowing down locations with targeted materials. For instance, Lunar Prospector (LP) quantied the abundances of ice water at the lunar polar regions during the last decade of the previous century. To achieve better resolution than these maps a satellite in a low altitude orbit or low periselene, below 30km, from the lunar surface is needed. This can be accomplished by a small satellite, like a CubeSat. We propose a hybrid gamma-ray and neutron detector based on scintillator technology for space exploration, sensitive to both gamma-rays in the spectral range of 30 keV to 8MeV and thermal to epithermal neutrons. The detector consists of an array of CLLBC scintillators that are read out by silicon photomultipliers attached to partially space-qualied read-out electronics developed by Integrated Detector Electronics AS (IDEAS). In the targeted conguration, the compact instrument will have the size of less than two CubeSat units (2U), where one unit is covered in Cd to allow for the distinction between epithermal and thermal neutrons. An understanding of the targeted radiation environment is vital for optimizing the instrument's design parameters before assembly. We report an environmental analysis for the Moon with the detector response simulated in GEANT4. With the detector response simulation, the detector design can be analyzed, and characterization measurement data from the physical instrument can be verifed. In this paper, we present preliminary results for the simulated detector response and compare them with measurements taken by a laboratory demonstrator, which was assembled and tested in a laboratory in 2023. First results look promising, showing that the targeted energy range for gamma-ray and neutrons can be detected. The performance of a monolithic prototype instrument will be elaborated and design decisions as well as the roadmap for the exploration instrument will be discussed.

• Virdis, Mario; Knutsen, Elise Wright; Kohfeldt, Anja; Jebali, Ramsey Al; Teodoro, Luis Filipe Alves & Skauli, Torbjørn [Show all 12 contributors for this article] (2024). University of Oslo CENSSAT-1 mission concept. Proceedings of the International Astronautical Congress. ISSN 0074-1795. Full text in Research Archive

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• Kohfeldt, Anja; Wahlén, Rebecka; Holdcroft, Sam; Teodoro, Luis Filipe Alves & Werner, Stephanie C. (2025). Element abundance mapping with the SER3NE Gamma-ray and neutron spectrometer. doi: 10.5194/epsc-dps2025-1439. Full text in Research Archive Show summary

  Selene’s Explorer for Roughness, Regolith, Resources, Neutrons and Elements (SER3NE) is a proposed small satellite mission in lunar orbit, aiming to characterize the lunar surface to unravel its volatile origin and delivery processes, in addition to uncovering the geological processes that shaped the Moon. Global element abundance mapping will prospect lunar resources for ISRU at future landing sites. Further, the mission is aiming to determine a more precise space-based neutron lifetime and the orbital evolution of the Earth-Moon system. To achieve these goals, SER3NE will host three instruments: a gamma-ray and neutron spectrometer (GRiNS, by UiO), the Lunar Infrared Point spectrometer (LIPS, by ROB/BIRA-IASB), and the SER3NE Laser Altimeter (S3LA, by DLR).Here, we present the current Gamma-Ray-including-Neutrons Spectrometer (GRiNS) design, performance specifications and preliminary results of the GRiNS laboratory demonstrator. GRiNS is part of the CLUNGAS family, that was reported on earlier.1By detecting gamma-ray and neutron radiation moderated by the lunar surface after GCR impact, GRiNS will be able to create global compositional maps and their abundances of different elements, such as Al, Ca, Fe, K, Mg, Si, Ti, Th, as well as hydrogen. In previous missions2 this was demonstrated with LaBr3 as main gamma-ray detector, proving the suitability of this technology. The default approach for hydrogen mapping are He3 pressurized tubes3, however, recently mission approaches with scintillator-based neutron detectors were launched4. In our approach we combine gamma-ray and neutron detection in one hybrid detector for reducing weight, cost, and space, and enabling deployment on small satellite missions.   GRiNS is a compact detector  capable of gamma-ray detection in the range of 100 keV to 8 MeV as well as the detection of thermal to epithermal neutrons. There shall be two detector units, facing nadir (for mapping) and zenith (in addition for neutron lifetime), as depicted in fig.1. The comparison of the ascending and descending gravitational bound thermal neutrons allow for the determination of the neutron lifetime along their flight path. The primary detecting material is a CLLBC (Cs2LiLa(Br,Cl)6:Ce), a dual-mode scintillator capable of both high-resolution gamma-ray spectroscopy and thermal to epi-thermal neutron detection. The preliminary detector layout aims for a 2x2 array where CLLBC is accompanied by lanthanum bromide (LaBr3), a crystal scintillator used in previous lunar mission2 for high-resolution gamma-ray spectroscopy, for improved gamma-ray – neutron discrimination. CLLBC and LaBr3 provide a good spectral resolution of

• Wahlén, Rebecka; Jebali, Ramsey Al; Teodoro, Luis & Kohfeldt, Anja (2025). A Gamma Ray and Neutron Spectrometer (GRNS) for mapping lunar surface composition and water abundance on the SER3NE mission. doi: 10.5194/egusphere-egu25-17007. Full text in Research Archive Show summary

  Selene's Explorer for Roughness, Regolith, Resources, Neutrons and Elements (SER3NE) is a lunar orbiter mission designed to map the topmost composition of the lunar surface, including elemental composition and water abundance. Planned instruments include a Gamma Ray and Neutron Spectrometer (GRNS) for elemental composition, including hydrogen indicating water, a Laser Altimeter (LA) for surface roughness and albedo observations, and a near-infrared spectrometer (LIPS) to determine water forms. The GRNS detector is designed for both in situ utilization as well as remote sensing. It has a core of CLLBC and LaBr3 crystal scintillators in a chessboard pattern for high-resolution gamma-ray detection (30 keV-8MeV) and thermal to epithermal neutron sensitivity. Gd foil on CLLBC allows separation of thermal and epithermal neutrons, while LaB3 and CLLBC enable advanced neutron detection analysis. Encapsulated by EJ-248M plastic scintillators, the detector includes anti-coincidence detector for charged particle rejection. With gamma-ray spectroscopy, rock-forming elements as well as KREEP and trace elements can be detected in the shallow surface of the moon. The local count rates of thermal and epithermal neutrons allow for the analysis of the distribution of hydrogen on the lunar surface, as well as for estimation of neutron lifetime from the lunar orbit. A demonstrator of the GRNS instrument has been successfully tested in the lab. A prototype of this lunar GRNS instrument will fly on the CENSSat-1 Bifrost CubeSat mission, scheduled for launch 2027.In this presentation, the GRNS instrument concept will be presented, focusing on the detector design and suitability for elemental composition analysis on a lunar orbiter.

• Holdcroft, Sam; Bocci, Alessio; Scholtz, Laura-Kristin; Retselis, Anastasios-Faidon; Knutsen, Elise Wright & Jebali, Ramsey Al [Show all 20 contributors for this article] (2025). CENSSAT-1 mission concept: a CubeSat for space weather monitoring. doi: 10.5281/ZENODO.17036544. Full text in Research Archive Show summary

  This paper presents an introduction to the CENSSAT-1 mission, an 8U CubeSat, which aims to study space situational awareness. It will investigate the effects of space weather on Earth from a 500 km orbit, using a camera, multi-purpose particle detector, and a Langmuir probe. It will additionally monitor space debris using a radar instrument, and conduct experiments on optimal control and drag based manoeuvring. CENSSAT-1 is aiming for launch in 2027.

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