Daniel Heynderickx

MULASSIS: a Geant4-based multilayered shielding simulation tool

Radiation shielding analysis is a crucial process in the spacecraft and space instrument development cycle. Simple tools such as SHIELDOSE-2 are used traditionally. With advances in computer and network technology and in energetic particle transport simulation codes, detailed Monte Carlo (M-C) simulation is no longer an approach reserved for research scientists but is widely becoming an important engineering tool. In this paper, we report on the main features of the multilayered shielding simulation software tool (MULASSIS) developed as part of the European Space Agency (ESA) activities in the Geant4 collaboration. It is based on the Geant4 M-C simulation toolkit developed by a large international collaboration lead by CERN. The software will be used as a general tool within ESA for radiation fluence, dose, and effects analysis. It has been integrated into the ESA SPENVIS system, thus, making it accessible to the wider space community over the World Wide Web.

Understanding space weather to shield society : A global road map for 2015-2025 commissioned by COSPAR and ILWS

There is a growing appreciation that the environmental conditions that we call space weather impact the technological infrastructure that powers the coupled economies around the world. With that co ...

Cross calibration of NOAA GOES solar proton detectors using corrected NASA IMP‐8/GME data

Solar proton flux measurements onboard Geostationary Operational Environmental Satellites (GOES) are of great importance as they cover several solar cycles, increasingly contributing to the development of long-term solar proton models and to operational purposes such as now-casting and forecasting of space weather. A novel approach for the cross calibration of GOES solar proton detectors is developed using as reference energetic solar proton flux measurements of NASA IMP-8 Goddard Medium Energy Experiment (GME). The spurious behavior in a part of IMP-8/GME measurements is reduced through the derivation of a nonlinear intercalibration function. The effective energy values of GOES solar proton detectors lead to a significant reduction of the uncertainties in spectra and may be used to refine existing scientific results, available models, and data products based on measurements over the last three decades. The methods presented herein are generic and may be used for calibration processes of other data sets as well.

New Geant4 based simulation tools for space radiation shielding and effects analysis

We present here a set of tools for space applications based on the Geant4 simulation toolkit, developed for radiation shielding analysis as part of the European Space Agency (ESA) activities in the Geant4 collaboration. The Sector Shielding Analysis Tool (SSAT) and the Materials and Geometry Association (MGA) utility will first be described. An overview of the main features of the MUlti-LAyered Shielding SImulation Software tool (MULASSIS) will follow. The tool is specifically addressed to shielding optimization and effects analysis. A Java interface allows the use of MULASSIS by the space community over the World Wide Web, integrated in the widely used SPENVIS package. The analysis of the particle transport output provides automatically radiation fluence, ionising and NIEL dose and effects analysis. ESA is currently funding the porting of this tools to a low-cost parallel processor facility using the GRID technology under the ESA SpaceGRID initiative. Other Geant4 present and future projects will be presented related to the study of space environment effects on spacecrafts.

SEPEM: A tool for statistical modeling the solar energetic particle environment

Solar energetic particle (SEP) events are a serious radiation hazard for spacecraft as well as a severe health risk to humans traveling in space. Indeed, accurate modeling of the SEP environment constitutes a priority requirement for astrophysics and solar system missions and for human exploration in space. The European Space Agencys Solar Energetic Particle Environment Modelling (SEPEM) application server is a World Wide Web interface to a complete set of cross-calibrated data ranging from 1973 to 2013 as well as new SEP engineering models and tools. Both statistical and physical modeling techniques have been included, in order to cover the environment not only at 1 AU but also in the inner heliosphere ranging from 0.2 AU to 1.6 AU using a newly developed physics-based shock-and-particle model to simulate particle flux profiles of gradual SEP events. With SEPEM, SEP peak flux and integrated fluence statistics can be studied, as well as durations of high SEP flux periods. Furthermore, effects tools are also included to allow calculation of single event upset rate and radiation doses for a variety of engineering scenarios.

Nowcast model for low‐energy electrons in the inner magnetosphere

We present the nowcast model for low-energy (<200 keV) electrons in the inner magnetosphere, which is the version of the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) for electrons. Low-energy electron fluxes are very important to specify when hazardous satellite surface-charging phenomena are considered. The presented model provides the low-energy electron flux at all L shells and at all satellite orbits, when necessary. The model is driven by the real-time solar wind and interplanetary magnetic field (IMF) parameters with 1 h time shift for propagation to the Earths magnetopause and by the real time Dst index. Real-time geostationary GOES 13 or GOES 15 (whenever each is available) data on electron fluxes in three energies, such as 40 keV, 75 keV, and 150 keV, are used for comparison and validation of IMPTAM running online. On average, the model provides quite reasonable agreement with the data; the basic level of the observed fluxes is reproduced. The best agreement between the modeled and the observed fluxes are found for <100 keV electrons. At the same time, not all the peaks and dropouts in the observed electron fluxes are reproduced. For 150 keV electrons, the modeled fluxes are often smaller than the observed ones by an order of magnitude. The normalized root-mean-square deviation is found to range from 0.015 to 0.0324. Though these metrics are buoyed by large standard deviations, owing to the dynamic nature of the fluxes, they demonstrate that IMPTAM, on average, predicts the observed fluxes satisfactorily. The computed binary event tables for predicting high flux values within each 1 h window reveal reasonable hit rates being 0.660–0.318 for flux thresholds of 5 ·104–2 ·105 cm−2 s−1 sr−1 keV−1 for 40 keV electrons, 0.739–0.367 for flux thresholds of 3 ·104–1 ·105 cm−2 s−1 sr−1 keV−1 for 75 keV electrons, and 0.485–0.438 for flux thresholds of 3 ·103–3.5 ·103 cm−2 s−1 sr−1 keV−1 for 150 keV electrons but rather small Heidke Skill Scores (0.17 and below). This is the first attempt to model low-energy electrons in real time at 10 min resolution. The output of this model can serve as an input of electron seed population for real-time higher-energy radiation belt modeling.

Toward Interplanetary Space Weather: Strategies for Manned Missions to Mars

Analysis of the interplanetary space weather environment will contribute to reducing uncertainties and assuring crew radiation safety.

Extreme internal charging currents in medium Earth orbit: Analysis of SURF plate currents on Giove-A

Relativistic electrons can penetrate spacecraft shielding and can damage satellite components. Spacecraft in medium Earth orbit pass through the heart of the outer radiation belt and may be exposed to large fluxes of relativistic electrons, particularly during extreme space weather events. In this study we perform an extreme value analysis of the daily average internal charging currents at three different shielding depths in medium Earth orbit as a function of L∗ and along the orbit path. We use data from the SURF instrument on board the European Space Agencys Giove-A spacecraft from December 2005 to January 2016. The top, middle, and bottom plates of this instrument respond to electrons with energies >500 keV, >700 keV, and >1.1 MeV, respectively. The 1 in 10 year daily average top plate current decreases with increasing L∗ ranging from 1.0 pA cm−2 at L∗=4.75 to 0.03 pA cm−2 at L∗=7.0. The 1 in 100 year daily average top plate current is a factor of 1.2 to 1.8 larger than the corresponding 1 in 10 year current. The 1 in 10 year daily average middle and bottom plate currents also decrease with increasing L∗ ranging from 0.4 pA cm−2 at L∗=4.75 to 0.01 pA cm−2 at L∗=7.0. The 1 in 100 year daily average middle and bottom plate currents are a factor of 1.2 to 2.7 larger than the corresponding 1 in 10 year currents. Averaged along the orbit path the 1 in 10 year daily average top, middle, and bottom plate currents are 0.22, 0.094, and 0.094 pA cm−2, respectively.

Simulation of the Radiation Environment Near Europa Using the Geant4-Based PLANETOCOSMICS-J Model

The Geant4-based PLANETOCOSMICS radiation simulation code has been extended to simulate the radiation environment in the vicinity of the Galilean moons. This software model treats in 3-dimensions the complex trajectories traced by charged particles in the combined effects of Jupiters and the moons intrinsic and induced fields. Furthermore, once the particles are incident upon the moons surface, the detailed nuclear and electromagnetic interactions are modeled and secondary particle emission treated. Treatment of these complex processes allows more accurate prediction required for radiation environment and hardness assurance for future missions to these moons. This paper describes the basis of the PLANETOCOSMICS-J model and the simulation approach for the Galilean moons. The first results from applying the model to Europa are presented and show potentially 60-75% reduction in total ionizing dose for 500 km to 100 km circular orbits around the moon.

Proton Spectra Detected by the Proton Switches on the CRRES Satellite

A thorough detector characterization method is described and applied to analyze the data from the proton switches flown on the Combined Release and Radiation Effects Satellite (CRRES). The results are compared with the CRRESPRO model based on observations of the proton telescope (PROTEL), which was on board the same satellite. A general good agreement is observed at positions where the flux of high energy protons is low. In regions of harder proton spectra, the CRRESPRO fluxes are higher than those deduced from the proton switches data. One possible explanation for this discrepancy may be that high energy protons penetrating into the PROTEL detector ly accounted for.