Nicolas André

1. Jupiter Radiation Environment Nicolas André RPWI Kick-Off Meeting, Uppsala, Sweden, November 26-27 2009

2. Jupiter Radiation Environments • 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

3. Jupiter Radiation Environments FromHank Garrett, JPL

4. Jupiter Radiation Environments

5. Jupiter Radiation Environments

6. Jupiter Radiation Environments 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

7. Jupiter Radiation Environments • ESA Approach #1 (2006-2009) 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)

8. Jupiter Radiation Environments • NASA/ESA Approach (2008-…) 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 !

9. Jupiter Radiation Environments • JGO Mission Profile 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

10. Jupiter Radiation Environments • 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

11. Jupiter Radiation Environments • Implications for the design of JGO Mission analysis From Arno Wielders, ESTEC From Karla Clark, JPL

12. Jupiter Radiation Environments • Implications for the design of JGO Jun et al., 2005 (GIRE)

13. Jupiter Radiation Environments • 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)

14. Jupiter Radiation Environments • 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)

15. Jupiter Radiation Environments • 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

16. 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/

17. Jupiter Radiation Environments • ESA Approach #2 (under QinetiQ contract) 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