New Ionising Radiation Models for Mars Missions: dMEREM and eMEREM
- Paper number
IAC-08.A1.4.8
- Author
Dr. Pete Truscott, Qinetiq Ltd., United Kingdom
- Coauthor
Dr. Fan Lei, QinetiQ Ltd, United Kingdom
- Coauthor
Mrs. Ana Keating, LIP, Portugal
- Coauthor
Ms. Sara Valente, LIP, Portugal
- Coauthor
Dr. Patricia Gonçalves, LIP, Portugal
- Coauthor
Dr. Laurent Desorgher, SpaceIT, Switzerland
- Coauthor
Dr. Norma Crosby, Belgian Institute for Space Aeronomy (BISA), Belgium
- Coauthor
Dr. Daniel Heynderickx, DH Consultancy BVBA, Belgium
- Coauthor
Ms. Hilde De Witte, BISA, Belgium
- Coauthor
Mr. Gérald Degreef, Belgian Institute for Space Aeronomy (BISA), Belgium
- Coauthor
Dr. Petteri Nieminen, European Space Agency (ESA), The Netherlands
- Coauthor
Dr. Giovanni Santin, European Space Agency (ESA), The Netherlands
- Year
2008
- Abstract
Unlike low-Earth orbit, which provides our only source of experience for long-term manned spaceflight, Mars mission spacecraft and landers will be exposed to cosmic rays and solar particles outside of the protection of the geomagnetic field. Once on the surface of the planet, the tenuous atmosphere provides little protection, and it is only at locations beneath the surface or within well-shielded habitats that the secondary radiation generated by cosmic rays starts to diminish. To better understand and quantify the Martian radiation environment, ESA has commissioned the MarsREM Project to develop two models (dMEREM and eMEREM) to predict particle fluxes and radiological doses in Mars satellite orbit, within the Martian atmosphere and for sub-surface conditions, as well as for the surfaces of Phobos and Deimos.
The Detailed Mars Energetic Radiation Environment Model (dMEREM) simulates the interactions of galactic cosmic ray ions, solar energetic protons and α-particles, and X-rays from solar flares, with the Martian atmosphere and planetary surface. The model is based on the Geant4 Monte Carlo radiation transport toolkit, and treats the detailed physical interaction processes (nuclear and electromagnetic), including simulation of all secondary particle propagation in 3D. dMEREM makes use of the European Mars Climate Database (MCD) to provide an accurate description of the location- and time-dependent atmospheric composition and density. Surface topology is based on the results of the Mars Orbiter Laser Altimeter, and the user can provide her/his own surface composition or select defaults. For the latter, the amount of dry-ice present in the polar regions is determined from the MCD, whilst data from the Mars Odyssey Gamma Ray Spectrometer is used to determine the concentration of water ice and iron (III) oxide for the user-provided longitude and latitude.
Whilst dMEREM provides a detailed simulation for precise prediction in scientific applications, the Engineering MEREM (eMEREM) predicts the radiation environment for Mars planetary and orbital conditions based on an extensive response function database from FLUKA radiation transport simulations. Depending upon the atmospheric density (from MCD) and surface composition, the response functions are integrated over the incident particle spectrum (cosmic-ray or solar particle protons or α-particles) to determine residual primary and secondary particle levels as a function of depth within the atmosphere.
This paper will review the foundations of these new models, the results to date (highlighting the importance of water on the local radiation environment), and accessibility of the models through the SPENVIS space environment web-site.
- Abstract document
- Manuscript document
(absent)