Mars images courtesy of ESA Portal Multimedia Gallery Mars Radiation Environment Characterization Results, previous and ongoing activities Ana Keating Ali Mohammadzadeh Petteri Nieminen Mario Pimenta Eamonn Daly MarsREC + Ongoing activities

16/11/063rd Space weather Week2 Outline  MarsREC model description  Radiation Environment at the surface –Fluences –Doses –Dose Equivalents  Variability of the Radiation Environment –Dependence on Time of the day –Dependence on Solar Longitude –Dependence on Landing Location  MarsREM ongoing activities –Dependence on soil density –Dependence on subsoil composition  Conclusions

LIP & ESA ESA 18121/04/NL/CH Ana Keating MarsREC 5º longitude

16/11/063rd Space weather Week4 Abstract MarsREC :  Integrated simulation tool for Mars Radiation Environment and Radiation induced Effect in EEE Components. –landing locations, time and season of the Martian year. MarsREC consists of two Modules: –Radiation Environment Characterization Module –Radiation Effects Module. Models features include –input solar cycle modulated GCR and SEP spectra, both based on CREME-96, –transport thru the Martian atmosphere and regolith, –creation of secondary radiation, using the Geant4 Monte-Carlo toolkit –atmosphere MCD –Seasonal and diurnal variations are considered for different location. –Surface topology (MOLA) Outputs: –Energetic particle transport histories, maps of radiation fluxes, doses dose equivalents and SEU rate predictions.

16/11/063rd Space weather Week5 Atmospheric Database  European Martian Climate Database (MCD) –Temperature, wind, density, pressure, radiative fluxes, etc –Stored on a 5ºx5 º, longitude-latitude grid from the surface to 120km –Height of each atmospheric layer –Fields (wind, temperature, pressure...) are averaged and stored 12 times a day (Mars Universal Time at longitude 0 o ), –for 12 Martian “seasons” –Each season covers 30º in solar longitude (L s )

MACLIDIG4MACLIDIG4 Updated version

16/11/063rd Space weather Week7 Topology  Radiation Environment mapping  Mars Orbiter Laser Altimeter (MOLA) on board NASA's Mars Global Surveyor (MGS) spacecraft. Data converted into a 5ºx5º Grid highly dependent on the topology.

16/11/063rd Space weather Week8 Atmosphere and Geology  The Martian atmospheric density being very low (in the order of magnitude of Kg m -3 ), works as a soft attenuator for incoming radiation.  Important contribution from secondary particles generated and backscattered at the surface of Mars.  Mars soil is about 3.75 g cm -3 and the mantle and crust bulk composition consist mainly of SiO 2 and Fe x O y.  The impact of different dust scenarios is not expected to be very significant!  Dust density is typically less than g/cm 2 (= 0.5x10 -3 % of the atmospheric density).

16/11/063rd Space weather Week9 Simulation Setup The geometry implemented in Geant4 program takes into account:  The pixel size given by the 5ºx5º accuracy of MCD, for each (long, latitude) location  Average composition of the soil of 30% Fe 2 O 3 and 70% of SiO2, and density of 3.75 g/cm3;  The thickness of the 32 atmospheric layers given by the sigma levels of MCD;  A fix atmospheric composition consisting of: –95% CO2 –2.5% N2 –1.25% Ar –1.15% O2 –0.07% CO –0.03% H2O  The atmospheric density, temperature and pressure are given by the 32 layers of the atmospheric table computed from MCD.  Different times of the Martian Day correspond to different geometry set-ups 5º

16/11/063rd Space weather Week10 Radiation inputs  CREME96 for near-Earth interplanetary.  Galactic cosmic rays (GCR) –Solar-quiet proton flux in the solar maximum –Simulated as isotropic momentum distribution: 10 5 protons  Particle events (SPE) –Energetic protons : “worst week” model –Simulated perpendicularly to the surface : 10 5 protons  Models are based on measurements at Earth (1AU)  The phasing in the solar cycle : foreseen for ExoMars.

16/11/063rd Space weather Week11 Analysed Locations  6 different Locations  North and South, East& West  Solar Longitude 180º-210º Tyrrena Paterae G, H, I, J A,B,C,D,E,F Different times of the Martian day at Long. 0º: 02h, 12h, 22h

16/11/063rd Space weather Week12 Olympus Mons cliff (I), 1.3 km of elevation Fluxes of Particles At low energies: n, , e - At high energies : p GCR: The Ions mainly: Deuteron, Triton, Alpha SEP: No significant signature of Ions Backscattering GCR 60% All particles 96% Neutrons Backscattering SEP 19% All particles 51% Neutrons due to GCR due to SEP

16/11/063rd Space weather Week13 Fluences and Doses Tyrrhena Paterae. Total fluence (one year GCR) of neutrons with energy higher than 30MeV at the surface of Mars for due to GCR protons, at A, B, D, F Fluence Maps Fluences *Considered event duration of 338 hours Doses due to GCR

16/11/063rd Space weather Week14 Ambient Dose Equivalent  MarsREC post-processing module  Uses the FLUKA fluence-to-ambient dose equivalent conversion coefficients,  For each kind of particles  Convoluted by the MarsREC fluence as function of particle energy

16/11/063rd Space weather Week15 Transfer Functions Fluence at the surface varies with the atmospheric pressure at the surface These results are due to : Denser air column that primary particles travel through, higher probability of interaction, absorption and spallation Backscattered neutrons mostly due to Primary protons Secondaries increasePrimaries decrease Backscattered neutrons decrease

16/11/063rd Space weather Week16 Dependence with Solar Longitude Total integrated fluence of all detected particles at the surface of Mars

16/11/063rd Space weather Week17 Day and Night Variations

16/11/063rd Space weather Week18 Low Energy Neutrons Variation  Neutrons E< 30MeV  Mars Univarsal Time Martian Longitude 0º: –22h : 191K –02h : 208K –12h : 248K  Fluences Per year ~ 5x10 8 n/cm 2  Temperature changes -> 1%

16/11/063rd Space weather Week19 Dependence on landing site Surface pressure = 189,4 Pa Surface pressure = 1004 Pa *Maximum Differences in fluence expected => 35% In particular:  N =57%  P = 12%  E = 37%  = 26%

Mars images courtesy of ESA Portal Multimedia Gallery Preliminar results, ongoing A. Keating M. Pimenta L. Desorgher F. Lei P. Truscott B. Quaghebeur P.Nieminen 19770/06/NL/JD MarsREM

16/11/063rd Space weather Week21  Merge and extending MarsREC & Mars-Planetocosmic models for the Mars, Phobos and Deimos, including treatment of surface topology and composition, subsurface, atmospheric composition and density (including diurnal and annual variations), and local magnetic fields.  Create a user-friendly engineering tool (QARM)  Interface with SPENVIS  New ion physics MarsREM Aim

16/11/063rd Space weather Week22 Dependence on soil:  & Composition MarsREM

16/11/063rd Space weather Week23 MarsREM Conclusions MarsREC framework is capable of:  Predicting RE at the surface (locations, solar longitudes, Time)  Tracking all primary and secondary particles (backscattering)  Predicting RE variation with climate changes along the Martian year.  Evaluating Dose Equivalents and Dose depositions at the surface of Mars  Calculating the energy spectra and particle species, radiation fluxes at component level, energy depositions and doses  Computing SEU rates in specific components. Results show:  TID at the surface of Mars is of lesser concern to EEE components,  Dose Equivalents are of major concern for manned missions  Relative abundance of protons and neutrons may result in important DD and SEE effects.  Results show good agreement with experimental data and other software predictions. MarsREM - Activities will improve and merge de existent models for Mars and Moons - Results expected to improve with description of new ion physics, soil information...