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Jupiter Radiation Environment. Nicolas André. RPWI Kick-Off Meeting, Uppsala, Sweden , November 26-27 2009. Jupiter Radiation Environments. Radiation effects . Radiation environments. Total Ionizing Dose (TID) - Cumulative long- term ionizing damage

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Jupiter

Radiation Environment

Nicolas André

RPWI Kick-Off Meeting, Uppsala, Sweden, November 26-27 2009


  • Radiation effects

  • Radiation environments

  • Total Ionizing Dose (TID)

  • - Cumulative long-termionizing damage

    • mainly due to protons and electrons

  • Displacement Damage Dose (DDD)

  • - Cumulative long term non-ionizing

  • damage mainly due to protons, electrons,

  • and neutrons

  • Single Event Effects (SEE)

  • - Event caused by a single chargedparticle

    • (heavy ion and/or protons) traversing

    • the active volume of microelectronicdevice

  • Charging

  • - Internalcharging, surface charging

  • Materialdegradation

  • Noise in science instrument

  • SolarEnergeticParticles (SEP)

  • - TID, DDD, SEE

  • GalacticCosmic Rays (GCR)

    • - SEE

  • Low-energy (<100 keV) Joviantrappedparticles

  • - surface charging, materialdegradation

  • High-energy (>100 keV) Joviantrappedparticles

  • - TID, DDD, SEE, IESD

  • FromInsoo Jun, JPL


    FromHank Garrett, JPL




    Salammbô “Family” of Radiation Models

    • Jupiter radiation physical modeling

      • - At ONERA, Toulouse, France (A. Sicard, S. Bourdarie)

      • At SwRI, San Antonio, USA (D. Santos-Costa)

    • Diffusion theory, Fokker-Planck transport equation

      • Boundary conditions based on spacecraft observations

      • Averaged trapped particle populations deduced from simulations

      • Comparison with spacecraft and synchrotron data

    • Various physical processes included


    Philosophy:

    Take advantage of all these pre-existing models by combining them together and then get the best specification we could obtain at the present time for any spacecraft which will fly in the Jovian magnetosphere

    In practice: (e.g., electron model)

    The model currently available at ESA allows to combine D&G83, plus GIRE plus Salammbô. The selection from one model to the other is done first according to L and then according to the energy.

    => JOP/JOE model provided by ONERA

    On-goingcontractwithQinetiq (ONERA) to improve the model and implementit in SPENVIS

    (engineering model)


    The end results of the models are used to constrain potential mission scenarios and estimate the total radiation dose.

    It is therefore critical tohave a good and robust understanding of the radiation environment of Jupiter.

    => Radiation Working Group set up (Dec. 2010)

    Recommandations only !


    Courtesy of Arnaud Boutonnet, ESOC

    (27/05/2008)

    The JGO willalwaysorbitbeyond ~12 Rj

    In orbitaround

    Ganymede

    Mission requirement: total radiation dose below 150 kradbehind 8 mm Al shielding


    • Implications for the design of JGO

    Jovian radiation belts (electron, protons) have been modelled empirically (D&G, GIRE) and physically (Salammbô) by various groups in the United States (JPL, SwRI) and in Europe (ONERA):

    a) different approaches

    b) different input parameters (e.g., magnetic field models)

    c) different spatial coverage

    d) different energy coverage

    Courtesy of Sébastien Bourdarie, ONERA

    EPD data

    The JGO willalwaysorbitbeyond ~12 Rj => use of the GIRE or D&G models


    • Implications for the design of JGO

    Mission analysis

    From Arno Wielders, ESTEC

    From Karla Clark, JPL


    • Implications for the design of JGO

    Jun et al., 2005 (GIRE)


    • The local radiation environment around Ganymede

    Khurana et al., Icarus, 2007

    When in orbitaroundGanymede:

    The JGO spacecraft (assumed ~POLAR) willencounterdifferentfieldlinestopology

    and, hence, different radiation doses

    Shieldingeffectfrom the moon not yetmodelled (itwilldecrease the dose)


    • The local radiation environment around Ganymede

    Khurana et al., Icarus, 2007

    Ganymede’s polar regions are brightened in response to being open to jovian plasma

    Leading/trailinghemisphericasymmetriesatlower latitudes (closedfieldlines)


    • The local radiation environment around Ganymede

    In blue:

    The countscorresponding

    to the Jovian plasma

    In red:

    Inside Ganymede’smagnetosphere

    Spike-likedecreasesobserved

    for ions and electrons:

    => Wewere on fieldlinesconnected

    to bothGanymede and jupiter

    Cleardecreaseobserved

    insideGanymede’smagnetosphere

    by a factor up to 10 !

    Williams et al., JGR, 1998


    • Jupiter Radiation Environments

      • A lot of (very) useful information exist on the web (Use it !!!) :

      • Adopt a coordinatedstrategywrtmodels and toolsusedbtw all RPWI teams

        • Necessary to understand/compare ourresults

        • Necessary dialogue with ESA (bothway): ourneeds / theirneeds

    • Recommendations

    http://opfm.jpl.nasa.gov/library/2009opfminstrumentworkshop/

    http://www.openchannelfoundation.org/projects/GIRE/


    Disadvantages of combining all existingmodelstogether: discontinuities …

    Re-analysis of all existing data, empricialfitsproposedundervariousassumptions

    Far frombeing mature and totallyagreed, but couldbe the reference model (ESA)

    in a few months (not before end of assessment phase …)

    => New Radiation model currently built by ONERAand reviewed by ESA and Radiation Working Group


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