1. Overview of the MarsREM Project Fan Lei, Ana Keating, Laurent Desorgher, Bart Quaghebeur, Francois Detraux, Hilde de Witte, Pete Truscott QinetiQ Ltd, Farnborough; LIP, Lisbon; SpaceIT, Bern; BIRA, Brussels Petteri Nieminen, Giovanni Santin ESA/ESTEC, Noordwijk Geant4 Workshop 2007, Hebden Bridge, Yorkshire The MarsREM Project is funded by the ESA Technology Research Programme under contract 19770/06/NL/JD Mars images courtesy of ESA PortalMultimedia Gallery

2. 2 Background Species and energy range of source particles –GCR: Very wide range in species, with noticeable dips after He and Fe Typical energy range of concern: 10’s MeV/A - 100’s GeV/A, although mean energy is several hundred MeV/A. –Solar particle events 10’s MeV/A to ~1 GeV/A: Impulsive, short-term events associated with solar flares have greater fraction of heavy particles CMEs produce gradual events that are proton-rich and last longer

3. 3 Background Data from W Schimmerling, J W Wilson, F Cucinota, and M-H Y Kim, 1998. Contribution of GCR and SPE ions very important to radiobiological dose in the interplanetary environment

4. 4 Background Assessment of influence of shielding on radiological effects of cosmic rays / solar particles –Long-duration manned spaceflight (interplanetary) –Investigating probability/possibility of extra-terrestrial life –Degradation of Martian “pregnancy test” kits - assessment of radiation on biological agents used to indicate presence of extra-terrestrial life Atmospheric interactions –Cosmic radiation at Earth strongly affected by the atmosphere and and to lesser extent surface materials: Secondaries maximise at ~60kfeet –On Mars low-density atmosphere means higher particle fluxes + surface materials more important: secondaries maximise beneath surface

5. 5 Project objectives Assess existing physics models in Geant4 covering energetic nuclear-nuclear and ion-electromagnetic interactions, and then develop, implement and verify additional or improved models Design, develop, implement and validate engineering tools, based on Geant4, to predict the Martian radiation environment for orbital spacecraft, and Mars planetary and moon landers or habitats The tools shall be easy-to-use by mission designers and planners (rather than developed just for radiation experts), web-based and interfaced with existing radiation shielding and effects simulation tools at the SPENVIS web-site Implement models to assess and compare the performance of passive and active radiation shielding, and apply to example cases to assess the performance of some active shielding cases

6. 6 The Detailed Model….

7. 7 dMEREM Developments such as: PLANETOCOSMICS (University of Bern) and MarsREC (LIP), detailed simulation models intended to provide precise predictions for scientific applications 5º Latitude 5º longitude

8. 8 Functional breakdown of the Detailed MEREM (dMEREM) application

9. 9 User inputs for mission parameters define source particle data Orbital ephemerides Start data / time & duration Long, lat, alts Ma.climate, Ma.weather Solar cycle Sp. Weather Start event Orbit generator (SAPRE-based) Physical occultation model for Mars + moons Long, lat, alt data with time GCR model CREME? SEP model (provisional: 1/R 2 scale JPL91, SPE?) X-ray flare (digitise example events) UV spectra (ECSS-E-10-04) Source radiation type Particle spectra (for duration) For orbiting spacecraft only For lander or habitat only Long, lat, alt data (I/F with SPENVIS) Source is cosmic ray Particle spectra (for duration) Particle spectra (for duration)

10. 10 Atmospheric Table -> MACLIDIG4 Location Surface Atmosphere

11. 11 Pre-Processor (SOILCOMPI) results summary Fe2O3 [Wt%] SiO2 [Wt%] H2O [Wt%] CO2 ice Thickness 0 8

12. 12 Detection Detailed Soil Description Detailed atmospheric description Detection at the surface or in height Mars Surface Soil CO2 if applicable Atmospheric layers

13. 13

14. 14 The Engineering Model….

15. 15 Functional breakdown of the Engineering MEREM (eMEREM) application Exposure function eMEREM Particle spectrum (for duration) Output requirements eMEREM G4 database eMEREM MCNPX database? eMEREM FLUKA database? Local topology & magnetic field conditions not included in eMEREM calculation Radiation dose & radiological dose Particle spectra (I/F with SPENVIS) dMEREM pre-processor Long, lat, alt data for orbit Start data / time & duration 

16. 16 Functional breakdown of the Engineering MEREM (eMEREM) database generation process

17. 17 Atmospheric effects Simple Model: Total depth ~ 22g/cm 2 CO 2 (95.%), N 2 (2.7%), Ar (1.6%) Scale height ~ 10.8 km Effects needs to be investigated: Temperature effect (neutrons) Effects of other rare elements (e.g. H 2 O, Ne) Scoping studies performed using FLUKA Soil/Rock ~ 50 km Atmosphere Amount of Air above Amount of Air below ~ 22 g/cm 2

18. 18 First Response Matrices Production 22 g/cm 2 in 22 layers (1g/cm 2 per layer), extend to 50 km altitude –H0.000014-C0.2637-N0.0174-O0.7041-Ar0.0147 14 layers for the ground 5000 g/cm2 thick –O0.4301-Mg0.0239-Al0.0560-Si0.1892-Ca0.0318-Fe0.2690 Proton or alpha incident particle, 100-1000000 MeV/n in 40 channels Radiation particle type recorded: e, γ, p, n, muons, pions and alpha Up/downwards particle energy spectra at layer boundaries –10 keV (1 eV, n) – 100 GeV FLUKA simulations and saved in Hbook files

19. 19 Albedo radiation at ~ 40 km altitude, for 22g/cm 2 and 8g/cm 2 atmosphere thickness Neutron radiation at the ground surface, for 22g/cm 2 and 8g/cm 2 atmosphere thickness

20. 20 Back scattered neutron spectra at the surface For ground soil densities of 3.4 and 2 g/cm 3 CO 2 ground compared to default ground Downward neutron spectra at the surface Back scattered neutron spectra at the surface H 2 O ground compared to default ground Downward neutron spectra at the surface Back scattered neutron spectra at the surface

21. 21 Nuclear-Nuclear Physics improvements….

22. 22 Existing Geant4 Nuclear-Nuclear Final State Models Binary Light Ions Photon Evap Multifragment Fermi breakup Evaporation Pre- compound Rad. Decay Ions Wilson Abrasion EM Dissociation Thermal 1 MeV 10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV (energy/nuc) Ablation (from T Koi, 28/07/06) JAM interface Intrinsic G4 Interfaced (not available publicly) JQMD interface INCL4/5-ABLA Nuclear-nuclear interactions for ion beam testing Atmospheric radiation propagation QQ is implementing interface between Geant4 and DPMJET2.5 model 5  10 11 GeV/nuc

23. 23 DPMJET-2.5 Interface –DPMJET treats hadron-nuclear and nuclear-nuclear interactions >5 GeV/nuc, with the upper limited reported to be of order 1000TeV –Two versions currently available, both of which treat nuclear-nuclear interactions: DPMJET-2.5 (Johannes Ranft) - source code publicly released DPMJET-3 (Stefan Roesler) - access to source controlled by Roesler –Under the ESA MarsREM contract, QinetiQ is developing an interface with DPMJET-2.5 (G4DPMJET2_5Model) specifically to treat nuclear-nuclear interactions. –Attempting to complete during September (delays due to debugging anomalies in the results).

24. 24 12 C on C @10 GeV/n

25. 25 Active Shielding Analysis Tools

26. 26 Development of Tools for Active Shielding Analysis Implement models to assess and compare the performance of passive and active radiation shielding, and apply to example cases to assess the performance of some active shielding cases

27. /MagneticFieldModels/RacetrackCoil/SetRout 1.25 m /MagneticFieldModels/RacetrackCoil/SetD1 5 cm /MagneticFieldModels/RacetrackCoil/SetD2 5. cm /MagneticFieldModels/RacetrackCoil/SetL1 3. m /MagneticFieldModels/RacetrackCoil/SetL2 0.01 m /MagneticFieldModels/RacetrackCoil/SetI 1700000. ampere /MagneticFieldModels/CreateAParametrizedField RacetrackCoil Field1 Racetrack Coil Linear Segment 1d numerical integration of the field produced by a surface current Circular Segment 2d numerical integration of the field produced by a surface current very time consuming

28. /MagneticFieldModels/CreateAParametrizedField RacetrackCoil Field1 #Replication of Field1 /MagneticFieldModels/ReplicateField/SelectField Field1 /MagneticFieldModels/ReplicateField/SetR 3. m /MagneticFieldModels/ReplicateField/SetPhi0 90. degree /MagneticFieldModels/ReplicateField/SetdPhi 7.2 degree /MagneticFieldModels/ReplicateField/SetNCopies 50 /MagneticFieldModels/CreateAParametrizedField ReplicateField Field2 Toroid Definition The time needed for computing the magnetic field from a toroid is too long - impossible to use this model in an extensive simulation. Therefore: Pre computing the field on a grid Interpolation of the field between grid nodes 3D Cartesian grid for the entire world 2D Cartesian grid for azimuthally symmetric field ~500x faster

29. 29 Status and summary Detailed and engineering models are being developed to predict the Martian radiation environment (in atmosphere, in orbit, and on moons) –Atmosphere & geology preprocessor generated –dMEREM and eMEREM applications being developed or in prototype –eMEREM database bing created These tools will ultimately be accessible thro SPENVIS website Improvements being implemented to nuclear-nuclear physics (DPMJET2.5) Developing active shielding analysis tools to enable analysis of efficacy of additional magnetic protection for astronauts