Specifying the electron radiation belts environment is crucial to enable satellite manufacturers and designers to adequately account for its harsh conditions, thereby mitigating risks of unforeseen malfunctions, data loss, and catastrophic failures that can impact spacecraft longevity. We present a novel statistical methodology for developing a radiation belt specification model that provides short- to long-term flux averages for spacecraft mission profiles, accounting for variability due to launch date and space weather/climate conditions. For this, we use an existing reanalysis database constructed using a physics-based radiation belt model and data assimilation. We analyse its flux distributions as well as the space and time correlation functions, and build a representative statistical model of the reanalysis database. Using this statistical representation, we build an innovative specification model prototype that is fast and easy to use, but can effectively be used for mission profiles at all timescales.

Calculating single event effect (SEE) rates is essential to ensure space mission reliability. Standard methods rely on ground data, which is not fully representative of the space radiation environment. In this article, we evaluate these methods using SEE data collected during 5.5 years from the single event upset (SEU) and single event latch-up (SEL) monitors aboard the Alphasat spacecraft in geostationary orbit.

During the second half of 2019, the Earth’s magnetosphere was impacted by a sequence of Corotating Interaction Regions (CIRs) during four consecutive solar rotations. Based on the solar wind properties, the CIRs can be divided in four groups, with the 3rd group, which arrived on August-September 2019, resulting in significant multi-MeV electron enhancements, up to ultra-relativistic energies of 9.9 MeV.Each CIR group has a different effect on the outer radiation belt electron populations; we investigate them by exploiting combined measurements from the Van Allen Probes, THEMIS, and Arase satellites. We produce Phase Space Density (PSD) radial profiles and inspect their dependence on the values of the first and second adiabatic invariants (μ,K), ranging from seed to ultra-relativistic electrons and from near-equatorial to off equatorial mirroring populations, respectively.Focusing on the 3rd CIR group, and in order to assess the relative contribution of radial diffusion and gyro-resonant acceleration, we perform numerical simulations of the radiation belt environment, combining several relevant models: EMERALD (NKUA), GEO model (NKUA), Salammbô (ONERA), VLF model (IAP), Plasmaspheric model (BIRA-IASB), FARWEST (ONERA). We further compare the temporal evolution of the simulated electron PSD with the above observations.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace project.

The Environmental Monitoring Units (EMU), on-board two satellites of the EU Galileo constellation, monitor the radiation environment along the GNSS orbit providing measurements of the energetic electron fluxes in the outer Van Allen Belt. With new calibration studies that take into account more realistic shielding provided by the spacecraft and the characteristics of the encountered environment along the satellite orbit, we have derived a new version of the GSAT/EMU Level 1 dataset that provides high quality validated fluxes of trapped energetic electrons within the 0.2-4.5 MeV energy range. In this work, we present an overview of the EMU measured electron fluxes over the last five years including recently completed validation studies with Arase [ERG] and RBSP energetic electron measurements. The new dataset, available to users from European member states registered at https://gssc.esa.int, will be used in the assimilation processes and/or the validation of the ONERA Salammbô electron radiation belt models - under the EU Safespace activity and ESA S2P RBFAN activity - leading to improved forecasts of the state of the outer belt. In addition, the quality of the time-coverage of the dataset permits their use in the development and/or evaluation of quantitative radiation environment specification models. This work has received funding from the European Union’s Horizon 2020 research and innovation programme "SafeSpace" under grant agreement No 870437, from the European Space Agency activity "Cross Calibration EMU Dataset with RBSP" under ESA Contract 4000135823/21/NL/GLC/mkn and the “SSA P3-SWE-X Space Environment Nowcast and Forecast Development” activity under ESA Contract 4000131381/20/D/CT.

The first two units of the ESA Next Generation Radiation Monitor (NGRM) sensor are flying onboard the European Data Relay System, Satellite-C (EDRS-C), and the Sentinel-6 Michael Freilich (S-6), providing critical information related to the space radiation environment. This work presents a first evaluation and analysis of the measurements of the unit hosted on EDRS-C during the geostationary transfer orbit (GTO) of the satellite. The evaluation studies include comprehensive comparisons with measurements from other radiation monitors and science-class experiments. NGRM datasets will become publicly available in real time from the space weather (SWE) data center through dedicated applications contributing to the monitoring of SWE and the characterization of the space radiation environment.

During July to October of 2019, a sequence of isolated Corotating Interaction Regions (CIRs) impacted the magnetosphere, for four consecutive solar rotations, without any interposed Interplanetary Coronal Mass Ejections. Even though the series of CIRs resulted in relatively weak geomagnetic storms, the net effect of the outer radiation belt during each disturbance was different, depending on the electron energy. During the August-September CIR group, significant multi-MeV electron enhancements occurred, up to ultra-relativistic energies of 9.9 MeV in the heart of the outer Van Allen radiation belt. These characteristics deemed this time period a fine case for studying the different electron acceleration mechanisms. In order to do this, we exploited coordinated data from the Van Allen Probes, the Time History of Events and Macroscale Interactions during Substorms Mission (THEMIS), Arase and Galileo satellites, covering seed, relativistic and ultra-relativistic electron populations, investigating their Phase Space Density (PSD) profile dependence on the values of the second adiabatic invariant K, ranging from near-equatorial to off equatorial mirroring populations. Our results indicate that different acceleration mechanisms took place for different electron energies. The PSD profiles were dependent not only on the μ value, but also on the K value, with higher K values corresponding to more pronounced local acceleration by chorus waves. The 9.9 MeV electrons were enhanced prior to the 7.7 MeV, indicating that different mechanisms took effect on different populations. Finally, all ultra-relativistic enhancements took place below geosynchronous orbit, emphasizing the need for more Medium Earth Orbit (MEO) missions.

Very often the satellite platform geometry as well as the equipment one are confidential and cannot be shared between partners in a space project. In order to perform radiation analysis at electronic component level, the 6-faces method is commonly used for geometry information exchange between primes and subcontractors. However, this method is known to be quite conservative. In the frame of the ESA funded project GTREFF the margins induced by the use of the 6-faces method were identified and analyzed for a typical geostationary mission. Following this, a new method was proposed and studied in the frame of a CNES funded project, with promising results.

Electron variability at geosynchronous orbit (GEO) plays a key role in satellite operations especially concerning the low energies which can lead to surface charging effects on spacecraft. In this work, we use 9 years (2011–2019) of electron measurements from GOES‐13, 14 and 15 satellites to study the evolution of electron fluxes with respect to various solar, solar wind, and magnetospheric parameters. The source electron fluxes are shown to be well correlated with AE index and Newell's function, while the seed electron fluxes are shown to be well correlated with solar wind speed. Based on these findings, we have developed a predictive multiple regression model for electron fluxes in the 30–600 keV energy range which uses solely solar wind parameters' measurements. The model may have a variety of applications related to the nowcasting/forecasting of the distribution of electron fluxes at GEO including serving as low‐energy boundary conditions for studying electron acceleration to relativistic energies or providing information for predicting surface and/or internal charging effects on spacecraft.

We investigate pitch angle distributions in the inner radiation belt for L-shells between 2-2.5 REarth and in the equatorial regions with B/B 0 of <1.05. The data from the INTEGRAL Radiation Monitor (IREM) onboard ESA’s INTEGRAL satellite is analysed for the years from 2010-2014 and 2019-2020 during its descent into the proton belt during two solar minima. The Proton Telescope (PROTEL) onboard the CRRES mission (NASA, U.S. Department of Defense; 1990-1991) is used for comparison of the data in the same regions, divided into a pre-storm, storm and post-storm period. The channels used for this study are most susceptible to protons and least affected by electron contamination. The pitch angles of the instruments to the magnetic field is retrieved and their countrate dependence is investigated. The peak countrates are observed at around 90°for all investigated channels. For IREM, the fitted anisotropy factor (n) is larger (n=8-9) for the lower energy channel (>12 MeV) for the L-shell 2 - 2.25 R E and lower (n=2-4) for the higher energy channels (>43 MeV). For L-shell= 2.25-2.5 R E the anisotropy factors for the lower energy channel are also large (n=6-7) and for the higher energy channels low (n=2-6). Similar behaviour is found for the PROTEL data. In the low energy channel (>11 MeV) the highest anisotropy (n=5.5) is found. During the storm the anistropy increases to about 20 in the higher energy channels (>44 MeV) and stays elevated in the post-storm period.

Abstract Accurate measurements of trapped energetic electron fluxes are of major importance for the studies of the complex nature of radiation belts and the characterization of space radiation environment. The harmonization of measurements between different instruments increases the accuracy of scientific studies and the reliability of data‐driven models that treat the specification of space radiation environment. An intercalibration analysis of the energetic electron flux measurements of the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron‐Proton Telescope (REPT) instruments on‐board the Van Allen Probes (VAP) Mission versus the measurements of the Extremely High Energy Electron Experiment (XEP) unit on‐board Arase satellite is presented. The performed analysis demonstrates a remarkable agreement between the majority of MagEIS and XEP measurements and suggests the rescaling of MagEIS HIGH unit and of REPT measurements for the treatment of flux spectra discontinuities. The proposed adjustments were validated successfully using measurements from ESA Environmental Monitoring Unit (EMU) on‐board GSAT0207 and the Standard Radiation Monitor (SREM) on‐board INTEGRAL. The derived results lead to the harmonization of science‐class experiments on‐board VAP (2012–2019) and Arase (2017–) and propose the use of the data sets as reference in a series of space weather and space radiation environment developments.

Initial conclusions of a feasibility study for a low-cost, short-duration mission to measure the space environment whilst simultaneously measuring effects on components, testing mitigation strategies and giving flight heritage to new detectors and components.

Solar energetic particles are one of the main sources of particle radiation seen in space. In the first part of September 2017 the most active solar period of cycle 24 produced four large X‐class flares and a series of (interplanetary) coronal mass ejections, which gave rise to radiation storms seen over all energies and at the ground by neutron monitors. This paper presents comprehensive cross comparisons of in situ radiation detector data from near‐Earth satellites to give an appraisal on the state of present data processing for monitors of such particles. Many of these data sets have been the target of previous cross calibrations, and this event with a hard spectrum provides the opportunity to validate these results. As a result of the excellent agreement found between these data sets and the use of neutron monitor data, this paper also presents an analytical expression for fluence spectrum for the event. Derived ionizing dose values have been computed to show that although there is a significant high‐energy component, the event was not particularly concerning as regards dose effects in spacecraft electronics. Several sets of spacecraft data illustrating single event effects are presented showing a more significant impact in this regard. Such a hard event can penetrate thick shielding; human dose quantities measured inside the International Space Station and derived through modeling for aircraft altitudes are also presented. Lastly, simulation results of coronal mass ejection propagation through the heliosphere are presented along with data from Mars‐orbiting spacecraft in addition to data from the Mars surface.

Ray-Tracing and Reverse Monte-Carlo are the two most widely used methods to estimate the dose at component level for space applications. The Ray-Tracing method is fast but presents intrinsic limitations while the Reverse Monte-Carlo method is more precise but more time consuming. In the frame of the ESA GTREFF project, a statistical comparison between these two methods has been performed, based on realistic satellite models for GEO orbit and using FASTRAD®. Results are presented and analyzed.

We present the analysis of data taken by the Space Application of Timepix Radiation Monitor (SATRAM). It is centred on a Timepix detector (300 mu m thick silicon sensor, pixel pitch 55 mu m, 256 x 256 pixels). It was flown on Proba-V, an Earth observing satellite of the European Space Agency (ESA) from an altitude of 820 km on a sun-synchronous orbit, launched on May 7, 2013. A Monte Carlo simulation was conducted to determine the detector response to electrons (0.5-7 MeV) and protons (10-400 MeV) in an omnidirectional field taking into account the shielding of the detector housing and the satellite. With the help of the simulation, a strategy was developed to separate electrons, protons and ions in the data. The measured dose rate and stopping power distribution are presented as well as SATRAM's capability to measure some of the stronger events in Earth's magnetosphere. The stopping power, the cluster height and the shape of the particle tracks in the sensor were used to separate electrons, protons and ions. The results are presented as well. Finally, the pitch angles for a short period of time were extracted from the data and corrected with the angular response determined by the simulation. (C) 2018 COSPAR. Published by Elsevier Ltd. All rights reserved.

The recent introduction of all-electric propulsion on geosynchronous satellites enables lower-cost access to space by replacing chemical propellant. However, the time period required to initially raise the satellite to geostationary orbit (GEO) is around 200 days. During this time the satellite can be exposed to dynamic increases in trapped flux, which are challenging to model. To understand the potential penalty of this new technique in terms of radiation exposure, the influence of several key parameters on solar cell degradation during the electric orbit raising period has been investigated. This is achieved by calculating the accumulation of nonionizing dose through time for a range of approaches. We demonstrate the changes in degradation caused by launching during a long-lived (hundreds of days) enhancement in megaelectron volt trapped proton flux for three different electric orbit raising scenarios and three different thicknesses of coverglass. Results show that launching in an active environment can increase solar cell degradation due to trapped protons by similar to 5% before start of service compared with a quiet environment. The crucial energy range for such enhancements in proton flux is 3-10 MeV (depending on shielding). Further changes of a few percent can occur between different trajectories, or when a 50-mu m change in coverglass thickness is applied.

We use electron flux derived from the environment monitoring unit "(EMU)-SURF" current monitor on board a Galileo Global Navigation Satellite System (GNSS) constellation satellite to modify and update the model of outer belt electrons for dielectric internal charging (MOBE-DIC). We describe how this data set, together with data from similar current-measuring instruments on Van Allen Probes, Giove-A, and STRV1d, are used to improve and expand the model. We have extended the spatial range to include the inner belt, exploited EMU data to widen the energy range for the electron spectrum, updated the statistical analysis of flux variation using a data set double the size used for the original model, and established a new and independent latitude function that yields improved agreement in medium earth orbit compared to the original model. The model is entirely characterized by a set of equations and parameters that produce fluxes as a function of magnetic coordinates at three distinct statistical levels.

The radiation data collected by the Standard Radiation Environment Monitor (SREM) aboard ESA missions INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory), Rosetta, Herschel, Planck and Proba-1, and by the high-energy neutron detector (HEND) instrument aboard Mars Odyssey, are analysed with an emphasis on characterising galactic cosmic rays (GCRs) in the inner heliosphere. A cross calibration between all sensors was performed for this study, which can also be used in subsequent works. We investigate the stability of the SREM detectors over long-term periods. The radiation data are compared qualitatively and quantitatively with the corresponding solar activity. Based on INTEGRAL and Rosetta SREM data, a GCR helioradial gradient of 2.96 % AU−1 is found between 1 and 4.5 AU. In addition, the data during the last phase of the Rosetta mission around comet 67P/Churyumov–Gerasimenko were studied in more detail. An unexpected yet unexplained 8 % reduction of the Galactic Comic Ray flux measured by Rosetta SREM in the vicinity of the comet is noted.

The radiation environment of the Galileo spacecraft is severe and poorly characterized. The Galileo orbit takes the spacecraft through the heart of the outer radiation belt, while the low levels of geomagnetic shielding throughout the orbit expose the spacecraft to intermittent intense fluxes of protons during solar energetic particle events. In the Galileo constellation, two environmental monitoring units (EMUs) are currently flying in two different orbital planes. These units monitor the radiation environment and provide critical information related to hazards for the host spacecraft and its payload. In this paper, we present the results from the analysis of the surface charge collecting plates and the proton telescope sensors. The performed numerical calibration of the EMU sensors and the application of novel unfolding and in-flight cross-calibration techniques allow the calculation of high-quality proton and electron differential fluxes. The creation of a high-quality, long-term EMU electron flux data set, is a step forward toward the improved characterization of medium earth orbit (MEO) environment through the update of the existing or the development of new radiation environment models.

The multifunctional spectrometer (MFS) is a radiation monitor installed on the X panel of the Alphasat satellite, in geostationary orbit (GEO) since July 2013. The MFS was specially tailored to characterize the space radiation environment in GEO and it is expected to acquire scientific data during a total lifetime of five years. An end-to-end Geant4 simulation of the MFS flight model based on the full geometry of the MFS, imported from computer-aided design (CAD) to geometry description markup language, was implemented and validated with the MFS ground-test results obtained in Paul Scherrer Institute facilities in 2010. The MFS simulation was then used to derive response functions for the MFS electron and proton channels. This paper describes the implementation of a maximum likelihood fit method to reconstruct particle spectra from MFS data, and its application to the reconstruction of the electron spectra for a 20-day period centered on the occurrence of January 2, 2014, solar energetic particle event. The obtained electron integral fluxes for this period are in reasonable agreement with GOES-15 public data and with the predictions of the AE8MIN update and IGE-2006 models.

The reliable and accurate calculation of incident particle radiation fluxes from space radiation monitor measurements, i.e. count-rates, is of great interest and importance. Radiation monitors are relatively simple and easy to implement instruments found on board multiple spacecrafts and can thus provide information about the radiation environment in various regions of space ranging from Low Earth orbit to missions in Lagrangian points and even interplanetary missions. However, the unfolding of fluxes from monitor count-rates, being an ill-posed inverse problem, is not trivial and prone to serious errors due to the inherent difficulties present in such problems. In this work we present a novel unfolding method which uses tools from the fields of Artificial Intelligence and Machine Learning to achieve good unfolding of monitor measurements. The unfolding method combines a Case Based Reasoning approach with a Genetic Algorithm, which are both widely used. We benchmark the method on data from European Space Agency’s (ESA) Standard Radiation Environment Monitor (SREM) on board the INTEGRAL mission by calculating proton fluxes during Solar Energetic Particle Events and electron fluxes from measurements within the outer Radiation Belt. Extensive evaluation studies are made by comparing the unfolded proton fluxes with data from the SEPEM Reference Dataset v2.0 and the unfolded electron fluxes with data from the Van Allen Probes mission instruments Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron Proton Telescope (REPT).