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

2. Jupiter Radiation Environments
Radiation effects
Radiation environments
Total Ionizing Dose (TID)
- Cumulative long-term ionizing 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 charged particle
(heavy ion and/or protons) traversing
the active volume of microelectronic device
Charging
- Internal charging, surface charging
Material degradation
Noise in science instrument
Solar Energetic Particles (SEP)
- TID, DDD, SEE
Galactic Cosmic Rays (GCR)
- SEE
Low-energy (<100 keV) Jovian trapped particles
- surface charging, material degradation
High-energy (>100 keV) Jovian trapped particles
- TID, DDD, SEE, IESD
From Insoo Jun, JPL

3. Jupiter Radiation Environments
From Hank Garrett, JPL

4. Jupiter Radiation Environments

5. Jupiter Radiation Environments

6. Salammbô “Family” of Radiation Models
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 ( )
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-going contract with Qinetiq (ONERA) to improve the model and implement it 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 to have 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 will always orbit beyond ~12 Rj
In orbit around
Ganymede
Mission requirement: total radiation dose below 150 krad behind 8 mm Al shielding

10. Jupiter Radiation Environments
Implications for the design of JGO
Jupiter Radiation Environments
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 will always orbit beyond ~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
Jupiter Radiation Environments
Khurana et al., Icarus, 2007
When in orbit around Ganymede:
The JGO spacecraft (assumed ~POLAR) will encounter different field lines topology
and, hence, different radiation doses
Shielding effect from the moon not yet modelled (it will decrease 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/trailing hemispheric asymmetries at lower latitudes (closed field lines)

15. Jupiter Radiation Environments
The local radiation environment around Ganymede
In blue:
The counts corresponding
to the Jovian plasma
In red:
Inside Ganymede’s magnetosphere
Spike-like decreases observed
for ions and electrons:
=> We were on field lines connected
to both Ganymede and jupiter
Clear decrease observed
inside Ganymede’s magnetosphere
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 coordinated strategy wrt models and tools used btw all RPWI teams
Necessary to understand/compare our results
Necessary dialogue with ESA (both way): our needs / their needs
Recommendations

17. Jupiter Radiation Environments
ESA Approach #2 (under QinetiQ contract)
Disadvantages of combining all existing models together: discontinuities …
Re-analysis of all existing data, empricial fits proposed under various assumptions
Far from being mature and totally agreed, but could be 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