Computational tools


The section's computational tools are sub-divided in the field of specialisation. Several tools are developed by the section itself or by industry under ESA contract.
 
General space environment models
 
The Space Environment Information System (SPENVIS) is a user-friendly World Wide web tool providing space engineers and scientists with information on the space environment and its likely effects on space systems.

The space environment includes radiation environment due to the radiation belts, solar particles and cosmic rays; the plasma environments of the ionosphere and geomagnetic substorms; neutral gaseous environments, including upper-atmospheric atomic oxygen; micro-meteoroids and space debris; magnetic fields; solar emissions.

SPENVIS also includes several tools for calculating effects (radiation dose, charging levels, impacts risks, etc.), and an interactive version of the ECSS Space Environment standard. The SPENVIS system provides easy access to tools via integrated user-friendly interfaces. Streamlined production of results, both in graphical and textual form, as well as background information and on-line help is available.
 
 
Radiation transport and effects
 
The Geant4 particle transport toolkit is jointly developed by a world-wide collaboration and is intended for a range of applications in high energetic physics, medical, and space physics and engineering fields. In recent years, space and astrophysics has become a significant user category, with applications ranging from instrument and detector response verification to space radiation shielding optimisation, component effects predictions, support of scientific studies, and analysis of biological effects. The various domains include:

  • Space electronics and space science detector systems
  • Simulations of astronaut radiation hazards
  • Planetary exploration applications
  • Interfaces and tools to space environment analysis tools such as SPENVIS
  • Cosmic ray magnetospheric propagation analyses
  • Microdosimetry
  • Large-scale simulations requiring event biasing and internet-connected platform (Spacegrid) capabilities
  • General shielding optimisation applications
MUlti-LAyered Shielding SImulation Software (MULASSIS) is a Monte-Carlo simulation based tool for dose and particle fluence analysis associated with the use of radiation shields. Users can define the shielding and detector geometry as planar or spherical layers, with the material in each layer defined by its density and elemental/isotopic composition. Incident particles can be any Geant4 particles, these include protons, neutrons, electrons, gammas, alphas and light ions. There is a wide choice for their initial energy and angular distribution. In addition, radiation spectra produced by ESA's Space Environment Information system (SPENVIS) can be inputted when the tool is used within this system.

The Sector Shielding Analysis Tool (SSAT) performs ray-tracing from a user-defined point within a geometry to determine shielding levels (the fraction of solid angle for which the shielding is within a defined interval), shielding distribution (the mean shielding level as a function of look direction) and total (TID or NIEL) doses. To achieve this, the tool utilises the fictitious geantino particle, which undergoes no physical interactions, but flags boundary crossings along its trajectory. Ray-tracing options include SLANT, NORM and WEIGHTED modes. Knowledge of the positions of these boundary crossings together with the density of the material through which the particle has passed can be used to profile the shielding (in g/cm^2, cm, or radiation lengths) for a given point within the geometry. The shielding information can be used, together with a user-provided external dose-depth curve, to determine the total dose at a point.

The shielding provided by the geometry can be sampled as a function of spherical polar coordinates q and f, and the user may control the extent of the solid angle sampled. The number of geantino histories followed, which determines the statistical accuracy of the results, is also set by the user.

Geant4 Radiation Analysis for Space (GRAS) is a Geant4-based tool that deals with common radiation analyses types (including TID, NIEL, fluence, path length, charge deposit, dose equivalent, etc.) in generic 3D geometry models. The main requirements for the development of the GRAS tool were flexibility and modularity of the application. Thanks to the flexibility, GRAS can be used for obtaining a variety of simulation output types for whichever (GDML or C++) 3D geometry model. This avoids the creation of a new tailored C++ Geant4-based application for every new project. Thanks to the modular design, the GRAS analysis type capabilities are being easily extended.

SHIELDOSE and SHIELDOSE-2 are computer codes for space-shielding radiation dose calculations. They determine the absorbed dose as a function of depth in aluminium shielding material of spacecraft, given the electron and proton fluences encountered in orbit. The codes make use of pre-calculated, mono-energetic depth-dose data for an isotropic, broad-beam fluence of radiation incident on uniform aluminium plane media. Such data are particularly suitable for routine dose predictions in situations where the geometrical and compositional complexities of the spacecraft are not known. Furthermore, the restriction to these rather simple geometries has allowed for the development of accurate electron and electron-bremsstrahlung data sets based on detailed transport calculations rather than on more approximate methods.

SHIELDOSE and SHIELDOSE-2 calculates, for arbitrary proton and electron incident spectra, the dose absorbed in small volumes of different detector materials for the following aluminium shield geometries:
  • In a semi-infinite plane medium, as a function of depth; irradiation is from one side only (the assumed infinite backing effectively insures this).
  • At the transmission surface of a plane slab, as a function of slab thickness; irradiation is from one side only.
  • At the centre of a solid sphere, as a function of sphere radius; irradiation is from all directions.

SHIELDOSE-2 Differs from SHIELDOSE mainly in that it contains new cross sections and supports several new detector materials, and has a better treatment of proton nuclear interactions.
 
 
Micro-meteoroids and space debris
 
The ESABASE2/Debris micro-meteoroids and space debris risk assessment tool was developed by eta_max space under ESA contract. The debris analysis software kernel is based on the former ESABASE Unix-Version, which now has been integrated into a PC-based framework.

ESABASE2/Debris provides wizards for the generation of spacecraft geometry models, and enables the import of ESABASE BAS-files as well as CAD-based geometries via a STEP import filter. Editors for the geometry, as well as for mission and debris/meteoroid analysis related input are available. The analysis results are provided by means of 3D and 2D graphics, but also as so called listing files containing tabled data.

ESABASE2/Debris provides an ergonomic and freely configurable graphical user interface. The current version of ESABASE2/Debris provides full geometry modelling and results analysis capabilities and comes with the "Debris" Application.

Meteoroid and Space Debris Terrestrial Environment Reference 2005 (MASTER-2005) is a software tool that can be used to analyze space debris flux and spatial densities. The following sources of debris are considered: launch and mission-related objects, explosion and collision fragments, solid rocket motor slag and dust, NaK droplets, surface degradation products, ejecta, and meteoroids. MASTER-2005 can deliver flux and spatial density analysis for all epochs between 1957 and 2055. For all historic epochs (up to the MASTER-2005 reference epoch - May 1st, 2005), the lower size threshold is one micron. The analysis of the future debris environment is possible based on three different future scenarios (business as usual, intermediate mitigation, full mitigation). The lower size threshold for future analysis is 1 millimetre.
 
 
Planetary environments
 
The Mars Climate Database (MCD) is a database of statistics describing the climate and environment of the Martian atmosphere. It is constructed directly on the basis of output from mulitannual integrations of a Global Climate Model (GCM) developed by Laboratoire de Météorologie Dynamique du CNRS (France) in collaboration with the University of Oxford (UK), the Instituto de Astrofisica de Andalucia (Spain), Service d'Aeronomie (France) with support from ESA and Centre National d'Etudes Spatiales (CNES).

The MCD can be used as a tool for mission planning and is applied to prepare for many missions in Europe and the USA. It also provides useful predictions for any scientist or mission design specialists.
 
 
Contamination
 
The COntamination Modelling Outgassing & Vent Analysis (COMOVA) tool is ESA's new reference software for spacecraft molecular external contamination modelling. It is operated in an open computing environment through the interfacing with commercial pre/post-processing tools.
 
 
Spacecraft plasma interaction
 
The Spacecraft Plasma Interaction System (SPIS) project aims at developing a software toolkit for spacecraft-plasma interactions and spacecraft charging modelling. Code development started in December 2002 by the ESA contractors, ONERA, Artenum and University Paris 7. This project also organises the SPINE meetings and coordinates with the wider plasma interactions community.

The SPIS code, while still being developed, is a physics-rich, 3D Particle-In-Cell (PIC), simulation software dedicated to accurate quantitative simulation of spacecraft plasma interactions and developed in the context of a European scientific and industrial network.

SPIS uses unstructured meshing schemes to describe the spacecraft and simulation volume geometry employing Capacitance-Matrix methods in the field derivation in order to model realistic 3D geometries.

The code is organized as an open and versatile object-oriented library and is fully written developed in Java. It is believed that this code will meet the requirements of the scientific community in terms of geometric and physics accuracy especially for instrument calibration and observational analysis. The summary of objectives for the SPIS project are to:

  1. Create a library of scientific numerical routines to perform spacecraft plasma interactions simulations in 3D;
  2. Provide this library free of charge to all potentially interested plasma modellers;
  3. Maintain and update the code via feedback from the users and a community of developers.

 
 
 
Last update: 4 April 2007


Related sites:

 •  Space Environment Information System (http://www.spenvis.oma.be)
 •  Geant4 for space (http://geant4.esa.int/)
 •  MULASSIS (http://reat.space.qinetiq.com/mulassis/)
 •  SSAT (http://www.space.qinetiq.com/geant4/ssat.html)
 •  GRAS (PDF) (http://ieeexplore.ieee.org/iel5/23/33493/01589198.pdf?tp= &arnumber=1589198 &isnumber=33493)
 •  ESABASE2/Debris (http://www.esabase2.net)
 •  MASTER-2005 (http://www.master-model.org/index.html)
 •  Martian Climate Database (http://www-mars.lmd.jussieu.fr/)
 •  COMOVA (http://wwwe.onecert.fr/comova/#)
 •  SPIS (http://dev.spis.org/projects/spine/home/)
 •  Spacegrid (http://www.spacegrid.org/)