Scope
Radiation shielding is essential to protect sensitive space hardware from the space environment, especially electronics and electrical systems, as well as for protection of crew for human spaceflight. Its optimisation is critical for all space systems, and is considered to be one of the biggest challenges for future exploration of the Moon and Mars.
This short workshop aims to map the current state of the art in Europe in the field of radiation shielding for space applications, and to define areas for future research. This will include traditional approaches to radiation shielding as well novel shielding techniques which could be enabling technologies for future missions.
Experts working in non-space domain are also very welcome to attend.
Workshop format
The format will be quite flexible, consisting of a combination of key note lectures, presentations, short pitches and posters. Space will also be available for product/company display if required. There will be sufficient time for discussion and networking during the breaks. The workshop is in-person only.
NUSES is a space mission proposed and coordinated by the Gran Sasso Science Institute (GSSI) in collaboration with INFN, several academic institutions, and Thales Alenia Space Italy (TAS-I). It comprises two key scientific instruments, known as Ziré and Terzina. Ziré is designed to measure the energy spectra of electrons, protons, and light nuclei up to about 300 MeV with the aim of studying low energy cosmic rays, monitoring the Van Allen belts and space weather phenomena, and analyzing magnetosphere-ionosphere-lithosphere coupling (MILC) systems. Moreover, gamma rays ranging from 0.1 to 10 MeV could also be detected.
To fulfil its mission objectives, Ziré relies on a detection system comprised of four primary sub-detectors: 1) a precision tracker based on the use of scintillating fibers, 2) an array of plastic X-Y scintillation bars, 3) a calorimeter utilizing lutetium-yttrium-oxyorthosilicate (LYSO) crystals as the detection target, and 4) an anti-coincidence system to tag background-induced events. A dedicated Low Energy Module (LEM) will extend the sensitive energy range down to the MeV scale for charged particles as well. The sub-detectors of Ziré are based on the use of silicon photomultipliers (SiPMs) to read out the scintillation light released by particle interactions in the target. Ensuring the proper operation of SiPMs in space poses challenges, particularly due to radiation-induced damage.
In this context, this contribution seeks to present the outcomes derived from simulations depicting the radiative environment encountered during the NUSES mission, focusing on Total Ionizing Dose (TID) and Total Non-Ionizing Dose (TNID) damage. Additionally, the contribution outlines the strategy employed to mitigate the expected radiation dose on the SiPMs
Composite materials provide an alluring alternative for radiation shielding in mass-sensitive environments such as spaceborne applications. The typical design flow starts with selecting key materials for the composite, determining the environment where it would be used, use some computer program, like Spenvis to determine the typical radiation spectra and use energy-transport programs, like Geant4 to optimize the composition to achieve the best shielding. When the pre-selection of materials is done based on simulation results it is mandatory to test the solution with irradiating the resulting material and measuring its shielding properties. To register the dose with and without shielding could be done with conventional detectors. In my talk I would like to give a cost efficient alternative to this traditional approach by introducing an COTS-based electronic framework which uses readily available COTS electronic components and matched measurement units to quantify the shielding efficiency of composite materials.
The high-energy particle composition below approximately 10 g/cm^2 of spacecraft and instrument material has been studied as a function of solar activity with galactic cosmic rays and solar energetic particles (SEPs) by using the images of the Metis coronagraph on board Solar Orbiter in the years 2020-2024.
A visual analysis of cosmic-ray matrices obtained with an algorithm implemented in the Metis electronics and Monte Carlo simulations have been carried out to study the composition of particles at the origin of the Solar Orbiter spacecraft's deep charging.
Proton energy spectra incident on the Solar Orbiter spacecraft measured by EPD/HET have been used as input data for the simulations.
We stress the importance of measuring SEP fluxes on board long-term space missions above hundreds of MeV, found to play a key role in affecting the performance of instruments hosted on board the satellites. To this end, we present the design of a new detector developed by the INFN-HASPIDE Collaboration.
Space radiation is one of the major showstoppers for the human exploration of the Solar System. Astronauts and mission-critical electronic devices are constantly exposed to highly energetic particles coming from deep space and the Sun, namely Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). Therefore, it is of paramount importance to study and characterize the possible effects arising from such an exposure. Ground-based studies have traditionally utilized particle accelerators with independent and serialized irradiation schemes, overlooking the synergistic effects of the complex radiation mixtures found in space. To address this gap, the necessity of developing a GCR Simulator has emerged. The concept behind the GCR Simulator at GSI is the use of a hybrid active-passive technology where the energy of the primary 56Fe beam is actively switched in conjunction with passive beam modulators. This approach allows for simultaneous irradiation with a continuous all-particle energy spectrum mimicking the complexity of the environment encountered in space.
In this presentation, we will discuss the design, implementation, and future challenges of the GCR Simulator at GSI-FAIR. In addition, we will show Geant4-based Monte Carlo simulations of the spectra resulting from the 6 different experimental setups whose combination is expected to match the reference GCR spectrum. A novel GCR Simulator, established through collaboration between GSI-FAIR and the European Space Agency (ESA), is now operational in Europe. With humans set to return to the Moon in this decade, and beyond in the near future, this facility provides a unique tool for replicating space-like environments on Earth. This advancement is crucial for enhancing our understanding of the effects of space radiation on matter, paving the way for future space exploration.
This work is supported by the European Space Agency (ESA), Directorate of Human and Robotic Exploration Program, contract # ECR-4000102355-03 and is performed in the frame of FAIR-phase-0 at the at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany).
We are developing at the SIS18 synchrotron at GSI (Darmstadt, DE) a new Galactic Cosmic Radiation (GCR) simulator to reproduce the space radiation environment on ground. The measurement and validation of the resulting radiation field is a major challenge due to its high complexity in terms of both particle population and broad energy distribution. One tool for studying mixed radiation fields, which is regaining importance over the last decade, is microdosimetry. Microdosimetry is particularly suitable for measuring highly mixed fields, producing microdosimetric spectra that span several orders of magnitude, ideal for highly heterogenic radiation fields. In addition, microdosimetric measurements provide an estimate of the radiation quality by collecting the energy deposition at the micrometer level, typical of cell dimensions, where energy deposition exhibits stochastic behavior, linking the biological effect more directly to its physical description.
To characterize the simulated GCR spectrum obtained at GSI with the new GCR simulator, several types of microdosimeters were used: silicon-based from the University of Wollongong (AUS), silicond-based from CERN (CH) and GSI's gas-based Tissue Equivalent Proportional Counter (TEPC).
In this talk, we will present the results obtained with the TEPC measurements of the 6 experimental setups required to recreate the GCR-like radiation. Furthermore, we will compare each of the 6 microdosimetric spectra with Monte Carlo simulations based on Geant4. Overall, it will be shown how microdosimetry is an essential tool to assess the extremely complex GCR-like radiation field experimentally produced at GSI.
This work is supported by the European Space Agency (ESA), Directorate of Human and Robotic Exploration Program, contract # ECR-4000102355-03 and is performed in the frame of FAIR-phase-0 at the at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany).
Materials to be deployed in space applications have to undergo a variety of different test scenarios, simulating actual space conditions. Among these materials solar photovoltaic cells, optics, meta-materials and more will be directly exposed to space radiation and must be tested accordingly. From the design phase of such target materials to the final production, it is important to obtain information about their behavior and performance in defined irradiation scenarios and qualify them following the directions of relevant ECSS/ESA standards. An excellent method to cover part of these tests in a laboratory scale is the high-flux, high-fluence electron irradiation with the help of industrial electron beam generators.
The collaboration has developed different irradiation test setups and procedures, adapted to the existing electron beam generators at IPF in Dresden, Germany covering an energy range between 100 keV to 1.5 MeV. The test setups, aiming for high electron flux, uniform and large irradiation field sizes, and their capabilities for use in irradiation qualification tests for space applications are described in this paper.
Further, we will describe an experimental setup developed aiming to irradiate samples under UV radiation (200 nm-400 nm) for accelerated test for solar effects according the relevant ECSS/ESA standards. This facility has been already used for projects belonging to large space programs (Cosmic Vision, Artes) for simulations up to 3,500 e.s.h. (equivalent sun hours). In particular, we detail the calculation of the UV dose delivered by Sun, the calibration of the detectors, the spatial distribution of the UV radiation on samples, the remote control 24/24-7/7 of both samples’ temperature and lamp radiation, the sample’s heat dissipation and operation in a helium atmosphere.
MRADSIM is an innovative modular software toolkit developed to simulate the effects of radiation on electronic components, human beings and materials. It has innovative features to increase parametric precision and to decrease computing time while adding additional functions to perform modular calculations specific for a range of applications. MRADSIM will be the first simulation toolkit using innovative AI/ML algorithms aiming to effectively identify potential problems induced by radiation thus helping to implement mitigation techniques to prevent catastrophic failures on mission-critical systems. These systems could be Earth based (manmade or natural) or space-borne. Unique features of MRADSIM will position it among the front-line tools to study the radiation susceptibility of the systems. The researchers from INFN (National Institute for Nuclear Physics) are the debuggers and commenters of MRADSIM.
MRADSIM needs to elaborate the following information: The detailed full geometry information in which there exists DUTs to be analyzed (i. e. electronic components inside satellites, large nuclear plants in which there is electronic/electromechanical instrumentation or human beings as targets) in a houses or habitats etc), selection of the DUTs to be analyzed, creation of radiation source model (nuclear explosion, local space radiation, radiotherapy sources, particle accelerators etc.). The transport of radiation from the source to the DUTs in order to analyze radiation effects on target materials and design appropriate radiation effects mitigations strategies if required. The modular architecture of MRADSIM allows to be easily tailored for various group of applications, so that the customers can choose the version that best fits to the type of DUTs/analysis they need to perform.
The cross-platform architectural design approach of the application is one of the most innovative aspects of MRADSIM, besides its best-in-class simulation and analysis capabilities, because it provides a seamless integration into existing customer infrastructures and minimizes changes in customer application. As a unique feature of MRADSIM, paramount importance has given to the implementation of innovative Artificial Intelligence (AI) and Machine Learning (ML) techniques to answer to the ever-increasing requirements of different markets to simulate the effects of radiation in many new application fields. The AI/ML use will provide possibility to simulate very large and complex projects exposed to harsh radiation environments by minimizing the need to use of large computing resources, long execution times as well as the necessity of the involvement of very highly skilled specialists [a very scarce resource] to run the projects.
GEANT4 is more and more used to model space environment effects on space systems. New and extended needs recently appeared with new missions, like for instance in 3D internal charging analysis or in the prediction of the Single Events Effects (SEE/SEU) in electronic devices. And radiations analysis, in its general terms, combine different processes and should be seen as a whole. To ease radiations analysis and address this, Artenum has build-up a self-consistency set of easy to use and interoperable tools. Innovative cases of application are presented and discussed.
As entry tool, EDGE is an interactive CAD tool dedicated to the modelling of geometries for radiations analysis, especially based on the GDML CAD format. Thanks to the recent evolutions of its STEP-AP importer, EDGE can now import rich geometries and simplify them. This importer also includes an innovative detesselation function, able to convert back to canonical CSG shapes and in most of the cases deeply optimises the imported geometries, significantly reducing the needed CPU effort in simulations. Downstream EDGE, MoOra is a frontal to the ESA/GRAS simulation kernel, allowing to fully set-up a radiations analysis through a simple GUI, including the import of GDML geometries, the settings of the environment and particles sources, as well as the definition of results to be extracted, like over time integrated dose or particles spectrum after shielding, for instance.
Regarding to Single Event (SEE/SEU), a new version of the open-source SEE-U single event prediction tool, developed by Artenum in partnership with ONERA, has been released last year. Through a fine 3D computation of the deposited energy of the incoming particles, with GEANT4, it is now possible to numerically evaluate the SEU cross-sections of digital devices for Ultra Deep SubMicron (UDSM) technologies depending on their design (size and the position of the transistors), independently on experimental measurements. Combined to MoOra/GRAS, for the computation of the particles spectra after shielding, and EDGE’s Sector Shielding analysis module, SAAM, SEE-U is able to evaluate the final Software Events Rate for selected devices in-situ the spacecraft structure and for realistic space environments. Moreover, SEE-U is now able to take into account the angular dependency of incident particles (including heavy ions and protons) on the final SER and remove the intrinsic limitations of previous models and methodologies based on Weibull’s fit.
Internal Charging is an another increasing risk factor, especially for missions passing through the radiations belts or in near PEO , such as constellations or heliosynchronous earth observation satellites. This is the focuce of the MoOra/GRAS/ SPIS-IC chain. Here, Monte-Carlo models are firstly used to compute the primary particles transport and deposited charges and doses rates inside the studied sensitive components. The internal charging code SPIS-IC is interfaced downstream then, to compute the detailed dynamics charges migration inside the dielectric and evaluate the resulting E-field and currents.
An innovating application of the MoOra/SPIS-IC internal charging chain has been recently done in the frame of the H2020 European project PAGER, where charging models have been integrated downstream space-weather forecast models to provide real-time charging risk forecast mission per mission and through simple indicators online. This successful integration has confirmed the relevance of the approach and the fact internal charging events might be not driven by punctual sever events only but may also result from a more dynamic and complex scenarios, gathering several successive medium amplitudes events and where the time variations of the space environment, on one hand, and the detailed dynamics of the charges migration inside the dielectric, on the other, must be modelled with care. Charging dynamic and environment variations are probably more relevant than a simple static “worst-case”.
FASTRAD is a software dedicated to the assessment of radiation effects in space. It is conceived, developed and distributed by TRAD. It contains various tools including modeling, calculation (with GEANT4 physics-based Monte-Carlo and Ray-tracing methods) and post-processing tools. We present here the main functionalities available to design, study and optimize the shielding in the scope of human exploration missions. Ongoing developments that will be include in the next version of FASTRAD are also discussed, notably the integration of Monte-Carlo calculation for heavy ions. We also present some of the current projects for space explorations we’re involved in, notably two PhD theses: one on the use of regolith as a shielding for lunar habitat (by Yulia Akisheva) and another one, on manned missions to Mars, including the development of an environment model as well as a multi-layer shielding optimization (by Gabin Charpentier).
Multilayer radiation shielding is only effective if it is optimised for the specific radiation environment in which it is used. Even though the parameter space of possible multilayer radiation shielding configurations is infinite, it can be systematically explored by simulating all permutations of pre-selected materials in layers of equal mass. Using the Geometry Description Markup Language (GDML), large numbers of shielding and detector volumes can be procedurally generated. The shielding performance can then be evaluated using Monte Carlo particle transport software like the ESA software Geant4 Radiation Analysis for Space (GRAS). It can track particle spectra through the shielding layers and record the Total Ionising Dose (TID) in detector volumes behind the shields. The configurations that lead to the lowest TID behind the shield can then be further optimised by varying the mass allocation between the layers.
As part of the Finnish Centre of Excellence for Sustainable Space (FORESAIL), several thousand multilayer configurations were simulated against the trapped particle spectra of the Van-Allen belts to determine the most effective shielding arrangement for minimal TID inside a CubeSat on Geostationary Transfer Orbit (GTO). Thousands of permutations with up to five layers of common satellite shielding materials were simulated. The best shields against the trapped particles use low atomic number (low-Z) materials (e.g. polyethylene) on top of high-Z materials (e.g. lead). Increasing the number of layers did not lead to any improvement in shielding performance. This contradicts previously published claims about “Z-graded” shielding with high numbers of layers, warranting further investigation. A selection of the best two-layer combinations was then further optimised by varying the mass allocation between the layers. If the two layers have a large difference in Z-number, the resulting TID versus mass allocation curves are highly non-linear. In the case of a low-Z material on top of a high-Z material, the minimum of the TID curve is up to 30% lower than the TID behind the same mass of either of the contributing materials. Optimisation of three-layer configurations consistently reduced the thickness of one of the materials to zero, which means three-layer shields were always less effective than the best optimised two-layer shields of the same mass.
To verify the findings of the simulations an instrument for the Foresail-2 CubeSat is proposed. It is planned to measure the dose rate behind polyethylene-lead two-layer shielding of five different mass ratios, as well as aluminium shielding of different thicknesses using RadFET TID sensors over a mission duration of 6 months on GTO.
The interactions of galactic cosmic and solar energetic particle radiation with planetary atmospheres and surface regolith/bedrock may lead to significant modification to the local surface particle field due to the attenuation of the primary radiation and secondary particle production in the materials. This paper introduces a new Geant4-based tool, GRAPPA, that generates GDML geometries and other associated inputs needed to perform 3D calculations of Martian and Lunar radiation environments using ESA’s GRAS model. GRAPPA produces position-, seasonal- and local time-dependent geometry and magnetic field information based on:
The input command set allows for easy control of the geometry, the dimensions of which can be for local (~10s metres) to planetary scales. For “local scale” GRAPPA surface geometries, recent changes to GRAS allow the user to easily overlay GDML-defined habitat geometries, mission equipment and anthropomorphic phantoms, thus allowing very detailed analyses of the local radiation environment on astronaut crews. This paper will include discussion of potential use-cases for the software and also briefly describe the GUI interface to GRAPPA provided through ESA's Human Interplanetary Exploration Radiation Risk Assessment System (HIERRAS).
This work will target the current challenges of radiation shielding in space through the lens of modern materials science, focusing on the development and optimization of novel shielding materials. We will examine innovative solutions such as tungsten composites, tungsten-based nonporous structures, advanced aluminium alloys, and high-temperature ceramics as potential shielding materials candidates. These are to be designed to offer multipurpose shielding capabilities, providing robust protection against both electromagnetic radiation and energetic particle irradiation. The integration of electromagnetic and particle radiation transport codes (such as MCNP, EVENT, SERPENT, etc.) with various material design criteria and shielding strategies remains an unresolved issue that needs to be addressed considering the irradiation environment of the space. Such a unified approach not only underscores the potential of new materials but also aims to enhance safety and functionality for space missions, including the protection of human crews. By integrating these advancements, the presentation sets the stage for significant breakthroughs in applying materials science to space exploration, paralleling our existing efforts to design new materials for shielding and structural components in Earth-based Small Modular Reactors (SMRs) [1], but that also find applicability in Micro-Reactors (MRs) [2–4] for space applications.
References
[1] Tunes, M. A., de Oliveira, C. R. E. & Schön, C. G. Multi-objective optimization of a compact pressurized water nuclear reactor computational model for biological shielding design using innovative materials. Nuclear Engineering and Design 313, 20–28 (2017).
[2] Parkison, D., Tunes, M.A. et al. Fabrication of bulk delta-phase Zirconium Hydride from Zircaloy-4 for use as moderators in microreactors. Scr Mater 239, 115771 (2024).
[3] Tunes, M. A. et al. Challenges in Developing Materials for Microreactors: A Case-Study of Yttrium Dihydride in Extreme Conditions. SSRN Preprint 4652643 (2024) doi:10.2139/SSRN.4652643.
[4] Tunes, M. A., Stemper, L., Greaves, G., Uggowitzer, P. J. & Pogatscher, S. Prototypic Lightweight Alloy Design for Stellar‐Radiation Environments. Advanced Science 7, 2002397 (2020).
The new age of space has given rise to many technological advancements in spacecraft design and manufacturing. A primary example is the space industry's migration from Aluminium to lightweight composite materials such as carbon fibre-reinforced polymers (CFRPs). However, limited information exists that explicitly assesses the radiation shielding performance in low earth orbit (LEO) of these lightweight composite satellite designs compared to the traditionally employed solid Aluminium structures.
In this work, we perform a comprehensive assessment of the radiation shielding provided by CFRP panels for satellites in LEO. A range of solid and sandwich panel designs to replace Aluminium as the primary structural panels for small satellites (< 500 kg). These panel designs, driven by engagement with industry partners, are being fabricated by the Space Technology and Industry Institute (STII) at Swinburne University of Technology, Australia as demonstrators for advancing Australia's domestic space capabilities. Here, we present a shielding performance study of these CFRP sandwich panels for the radiation exposure conditions expected for LEO missions. The radiation shielding performance is assessed via Geant4 simulations that calculate the reduction in absorbed dose, the particle species and energy spectra of the satellite's internal environment, and the resulting quality factor of the internal radiation field. Preliminary results demonstrate the feasibility of CFRP panels to provide adequate radiation shielding to support mission lengths of over 1000 days, based on typical lifetime dose limits for commercially available electronics. To further extend these mission lifetimes, we explore the use of thin, metallic (high Z) foils and spray coatings. To validate the results of this simulation study, experimental measurements will be conducted at accelerator facilities. The results of this work align with multiple of the conference themes, including multi-layer and composite shielding, radiation shielding modelling, experimental testing and validation of shielding, and shielding solutions for small satellites.
The pursuit of ‘Active shielding’, whether magnetic or electrostatic, has often felt like chasing a mirage. However, the effectiveness of magnetospheres on Earth hints at a viable path forward. Complex engineering proposals to safeguard spacecraft or lunar bases have consistently encountered obstacles: heavy hardware, demanding power requirements, and disruptive effects on other systems. These challenges stem from oversimplified models assuming that energetic ions can be solely controlled by the Lorenz force from artificial electric or magnetic fields, overlooking the complexities of interplanetary space as a near-perfect plasma. This necessitates a shift towards understanding the interaction of energetic particles with magnetospheric environments, emphasizing the importance of miniaturizing magnetospheres for practicality. Despite initial doubts regarding the deflection capabilities of mini-magnetospheres, observations of natural phenomena highlight their effectiveness in scattering particles through turbulence, collisionless shock, and diamagnetic cavity formation. The key challenge lies in enhancing and optimizing these effects within an artificial system.
Inspired by analyses of natural phenomena such as the Moon's mini-magnetospheres and artificial comet experiments, AEGIS (Active Electromagnetically Generated Inductive Shield), an ESA-funded GSTP project led by RAL Space, the University of Oxford, and Strathclyde, endeavors to harness electromagnetic shielding techniques for spacecraft and astronaut protection. By integrating insights from natural occurrences and laboratory research, AEGIS aims to revolutionize space radiation protection by effectively managing and manipulating ‘miniature’ magnetospheres, drawing on techniques developed in laser plasma accelerators and fusion tokamaks. This approach holds the promise of overcoming past limitations and providing a realistic solution for active shielding, complementing passive shielding as solar storm shelters, akin to the protection offered by Earth's magnetic field.
With constant evolutions in materials composition due to regulation, geo-political issues or innovation, materials resistance under radiation is still an important chapter in materials qualification. With the cost and duration issues, rationale to perform or not testing is weighted carefully. On the other hand, with more stringent mission and extended mission duration, an adequate approach in order not to overtest materials is needed.
In this background, this presentation will recall a quick overview of COMET CNES workshop on modelisation and impact of space radiations on materials to focus on some tools and modelisation means for evaluation radiation effects on materials. In a second part, methodology for testing materials behavior under radiations will be described.
As a response to an ESA call a contracted R&D activity is running with ambition to develop new efficient, lightweight radiation shielding solution for electronic components on GEO telecommunication satellites. Based on physical understanding of interactions of different kind of radiations with different target materials our idea is to use optimized combination of low and high Z materials either in a multilayer stack or composite structure. Both the geometrical and material thickness of the shielding is constrained by an equivalent of 5 mm (1.35 g/cm2) of aluminum. For the optimization we have used the relevant space radiation environment in GEO including trapped electrons and mission fluence of solar particle event protons. The Geant4, HZETRN2015 and Shieldose2 transport codes were used for model calculations. For optimization purpose the total ionizing dose in silicon-dioxide was selected as response parameter. With the same areal mass density as of 5 mm aluminum we predicted around 45% dose reduction using our optimized configuration. Our novel shielding stacks were already tested for total ionizing dose reduction capabilities using electrons from a LINAC electron accelerator with degraded energy from a 6 MeV nominal energy. Our shielding stacks have been proven to perform accordingly to model simulations and for this particular radiation field they reached nearly 70% dose reduction when compared to aluminum.
It is well known that space radiation environment, which has contributions from galactic cosmic rays (GCRs), solar energetic particles (SEPs), and the trapped particles within the Van Allen belts, directly influences space systems. These systems rely on complex and fragile electronic devices, which, as a consequence of the action of the radiation and its related phenomena: total ionizing dose (TID), single event effects (SEE) and displacement damages (DD), its performance could be degraded. This could cause failures to arise due to different mechanisms, from parametric drift - failures, such as leakage current, threshold voltage, among others, to destructive effects, like single event Latch up (SEL) or single event burn-out (SEB).
These failures in the electronics affect the systems reliability and its performance, which could compromise the mission success. Considering this, the main objective of the SRPROTEC project is to develop and validate new composite materials with better shielding performance against space radiation, in order to increase the radiation tolerance of microelectronic devices built employing these materials.
For this purpose, different composites will be synthesized using liquid resins and solid epoxy-based matrixes, mixed in different proportions with two main fillers: Bi2O3 and Al2O3.
These developed materials will be exhaustively characterized: tensile and flexural strength tests, hardness test, thermomechanical analysis, thermal, electrical and moisture absorption characterization, rheometry, outgassing test, etc., will be performed, to ensure the new materials show not only enhanced radiation shielding levels, but also the required properties for materials to be suitable for packaging of microelectronic devices.
Then, after the material characterization is completed, the best formulations will be chosen to encapsulate real electronic components, using different semiconductor dies with known radiation sensitivity, which will be used as test vehicles. A test campaign will be designed and performed based on classic validation test sequence at component level, including: radiation tests, environmental stress tests, physical test (scanning acoustic microscopy, external, radiographic inspection, etc.).
Finally, the presentation will cover a summary of the project objectives, a description of the work packages, as well as the new developments achieved.
Besides standard shielding materials such as Aluminum and plastics also composite materials are being increasingly used in space. Knowledge of their shielding effectivity, which is essential for customized design and their optimal deployment on spacecraft, is available namely from models or numerical calculations. In this work, detailed experimental data is provided by dedicated measurements from particle accelerator beams (protons, electrons) and well-defined reference fields (gamma rays, X rays). High-resolution wide-range results are obtained by using the semiconductor pixel detector Timepix which provides photon-counting response, radiation-type sensitivity and quantum-imaging visualization of varying radiation fields. Applying the spectral-sensitive technique of particle tracking on single particle tracks, the radiation field decomposition is directly measured in detail of the transmitted field (shielded) and open field (non-shielded). Changes in the primary beam/field are resolved as well as the onset of secondary component. Small and wide-range variations are produced in terms of field composition, flux, dose rate, deposited energy spectra (energy loss) and linear-energy-transfer (LET) as well as position and also direction. Extensive experimental results are provided on a collection of composite materials of specific composition and are evaluated/compared with standard nuclear shielding materials (Al, steel, plastic/PE, lead).
Developing and studying radiation protection shielding solutions is of paramount importance as enabling technologies for manned exploration missions beyond Low Earth orbit (LEO). As astronauts venture further into space, they face increased exposure to space radiation, which poses significant health risks.
Thales Alenia Space (TAS), a leading space technology company, has been and is currently involved in multiple projects and studies focused on radiation shielding technologies for manned explorations TAS's involvement primarily centres around its system engineering capabilities, innovative shielding materials and solution, complex Monte Carlo simulations, and as potential user of the developed technologies, as it is a leader in orbital infrastructure for human flight.
The aim of the talk is to give an overview of the TAS activities and expertise in radiation shielding projects l(e.g. PERSEO, SR2S,ROSSNI; HEARTS). Additionally, leveraging the experience gained from the PERSEO project, TAS has collaborated with D-AIR LAB to explore the development of a radiation protection suit for potential use in manned exploration missions beyond low Earth orbit (LEO).
The ROSSINI (Radiation Shielding by ISRU and Innovative Materials for EVA, Vehicles, and Habitats) projects, funded by the European Space Agency (ESA), were dedicated to investigating innovative shielding techniques for deep space and planetary manned exploration missions. Several passive shielding material solutions were studied, manufactured and tested during the projects evolution, including Moon and Mars regolith simulants, as well as multilayer and composite materials and innovative materials with high Hydrogen content. Test campaigns were conducted during the projects to evaluate the selected materials' shielding effectiveness using high-energy ions and proton beams. The experimental results were compared with various Monte Carlo simulation codes, such as Geant4/GRAS, PHITS, and FLUKA.
Additionally, complex simulation models were developed to evaluate radiation fields in different mission scenarios, including deep space, moon and Mars surface missions. These activities also led to the creation of a Reference Radiation Simulation Scenarios, a collection of MC macros and detailed geometry models with the purpose to provide access to end-users in the space (exploration) domain to realistic modular geometry elements for their radiation simulations. As a result of these activities, a Reference Radiation Simulation Scenarios was created. This comprises a collection of Monte Carlo models, specifically designed to offer end-users in the space exploration field access to realistic modular geometry elements for their radiation simulations.
Deep-space radiation is among the biggest hindrances to human space exploration. Therefore, radiation protection in space is a very active field of research. Despite its limitations, passive shielding is currently the most promising radiation protection strategy. It consists of adding shielding material to the walls of spacecrafts and planetary bases. Throughout the ESA-funded ROSSINI3 and DEIMOS projects, accelerator-based experimental campaigns were performed, respectively, at the GSI (Helmholtz Centre for Heavy-Ion Research) and HIT (Heidelberg Ion-Beam Therapy Centre) facilities with some of the most relevant ion beams for radiation protection in space. These beams included high and low-energy protons, He and Fe-ions. Targets included several structural (aluminium alloys), in situ (Moon regolith and concrete simulants), standard (high-density polyethylene), and innovative shielding materials (Li-based hydrides, pure and stabilised in a paraffin matrix). For long-duration exploration scenarios, heavy ions are the main contributors to the biological effects of cosmic radiation behind thin shields, while light ions are behind thick shields [1]. While the predominant effect with Fe-ions is dose attenuation due to projectile fragmentation [2], a strong inverse shielding effect (dose buildup) is observed for light ions [3].
The experimental data were compared with the simulation results of the most commonly used Monte Carlo codes in this field of research, namely FLUKA, PHITS, and Geant4. The simulations showed significant and systematic differences among the codes mainly due to the different nuclear cross-section models.
Therefore, two nuclear cross-section databases (total reaction [4] and fragment production [5] cross-sections) were generated. The collected nuclear reaction cross-section data were compared to the parametrisations used in the Monte Carlo codes. An optimisation of one of these parametrisations (the Tripathi-Cucinotta-Wilson) was proposed [6]. An important gap in the experimental data was also pointed out for high energies. The databases are available for open access online [7].
[1] Norbury, John W., et al. "Are further cross section measurements necessary for space radiation protection or ion therapy applications? Helium projectiles." Frontiers in Physics 8 (2020): 565954.
[2] Luoni, Francesca, et al. "Dose attenuation in innovative shielding materials for radiation protection in space: measurements and simulations." Radiation Research 198.2 (2022): 107-119.
[3] Luoni, Francesca, et al. "Dose Build-Up of High-Energy 1H and 4He Ions in Standard, Innovative, and In Situ Shielding Materials: Measurements and Simulations" in preparation for Communications Physics
[4] Luoni, F., et al. "Total nuclear reaction cross-section database for radiation protection in space and heavy-ion therapy applications." New Journal of Physics 23.10 (2021): 101201
[5] Luoni, Francesca. "Radiation Shielding during Deep-Space Missions: Dose Measurements, Monte Carlo Simulations, and Nuclear Cross-Sections." (2023).
[6] Luoni, F., et al. "Optimisation of the Tripathi model using a nuclear reaction cross-section database." New Journal of Physics 25.12 (2023): 123024.
[7] https://gsi.de/fragmentation
Preparing for human exploration on Mars is a challenging task when it comes to shielding from cosmic radiation for inevitable long-term stays. The equivalent dose at the surface – 0.64 mSv/day in average measured by the Curiosity rover [1] – combined with the dose received while in transit can amount to a value higher than the limit established for the entire career of an astronaut (1 Sv [2]). One option for radiation mitigation explored in the literature is the use of regolith as a shielding material [3,4], for example in the construction of habitats, given an appropriate wall thickness.
Here, we aim to develop adobe structures for radiation shielding by employing slurries from clay-bearing regolith and brine simulants for Additive Manufacturing (AM). The deliquescence of regolith minerals, forming brines with eutectic temperatures lower than the freezing point of pure water [5-7], gives plasticity to clay-rich soils – an appropriate feedstock for Material Extrusion (ME). The goal is to use the mineral diversity and hydration states of the Martian soil to produce multi-layer shields using a layer-by-layer approach with AM. Combining high-Z and hydrogen-rich materials that target specific types of radiation can improve the efficacy of the shield. Radiation shielding simulations performed on models of regolith simulants from different Martian sites show differences in particle transport, in which the type of radiation determines the performance of the material. Irradiation tests will support an investigation on deviations between theoretical and experimental results, possibly supporting the development of models for complex materials systems such as regolith.
References
[1] Hassler, D.M., et al., Mars’ Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover. Science 2014;343(1244797), DOI:10.1126/science.1244797.
[2] Straube, U., Berger, T., Reitz, G., Facius, R., Fuglesang, C., Reiter, T., et al., Operational radiation protection for astronauts and cosmonauts and correlated activities of ESA Medical Operations. Acta Astronautica 2010;66:963–73, DOI:10.1016/j.actaastro.2009.10.004.
[3] Meurisse, A., Cazzaniga, C., Frost, C., Barne, A., Makaya, A., Sperl, M., Neutron radiation shielding with sintered lunar regolith. Radiation Measurements 2020;132:106247, DOI:10.1016/j.radmeas.2020.106247.
[4] Un, A., Sahin, Y., Determination of mass attenuation coefficients, effective atomic numbers, effective electron numbers and kermas for Earth and Martian soils. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 2012;288:42–7, DOI:10.1016/j.nimb.2012.07.031.
[5] Chevrier, V. F., Rivera-Valentín, E.G., Soto, A., Altheide, T.S. Global Temporal and Geographic Stability of Brines on Present-day Mars. Planet Sci J 2020;1(3):64, DOI:10.3847/psj/abbc14.
[6] Nuding, D. L., Davis, R. D., Gough, R. V., Tolbert, M. A., The aqueous stability of a Mars salt analog: Instant Mars. J. Geophys. Res. Planets 2015, 120,588–598, DOI:10.1002/2014JE004722.
[7] Möhlmann D, Thomsen K. Properties of cryobrines on Mars. Icarus 2011;212(1):123–30, DOI:10.1016/j.icarus.2010.11.025.
In a recently completed ESA activity, the collaborating parties aimed at developing efficient lightweight radiation shielding materials for manned deep space missions focusing especially on Moon orbiting and Lunar landing missions. Galactic cosmic rays (GCRs) from protons to uranium ions at solar maximum and solar minimum as well as protons from selected historic extreme solar particle events (SPE) were considered as primary sources of the space radiation environment. On Moon orbit and on the Moon surface lunar secondary (albedo) particles were also considered. Radiation shielding properties were studied by computer simulations for composites that combined different amount of a great variety of high hydrogen content materials in a carbon-fiber reinforced epoxy matrix. We have used the Geant4 and the HZETRN2015 transport codes for model calculations. The effective dose and dose equivalent, which are relevant for stochastic effects and tissue reactions in humans, were calculated in tissue equivalent material as response parameters. Optimization was constrained by special requirements that must be met under the harsh space environment for the selected composites.
A number of test samples of the selected composite type were manufactured for ground-based radiation shielding property testing. Gamma and accelerator-based neutrons, both with wide and monoenergetic spectra were used for radiation testing. In addition to shielding properties the radiation hardness, mechanical characteristics (uniaxial tensile-, flexural strength), and thermal degradation of the selected composite were also laboratory tested up to 170 krad (1700 Gy) of absorbed dose.