1. Theoretical Models in support of RPWIIo
Ganymede
Europa
I. Mueller-Wodarg
Imperial College London

2. Plasma environment Europa Ganymede Callisto Bo (nT) 370-460 64-113
4-42
Ne (cm-3)
18-250
1-10
Ti (eV)
50-400
10-100
Te (eV)
100
300
500
Orbital vel (km/s) 14 11 8
Plasma vel (km/s)
70-100
95-163
Alfvén speed (km/s)
Ped conductance (S)
~30 2
~1000
Plasma freq e- (kHz)
38-140
9-28
Plasma freq ions (Hz)
Ion gyroradius (km)
8-12
36-13
530-34
Pickup ion gyro-r (km)
19-15

3. Atmospheres of Galilean Moons
Formation: Sputtering
Surface sputtering by magnetospheric ions (primary)
Sputtering by ionospheric pickup ions: accelerated by corotation electric field (secondary)
Loss:
Thermal escape (Jeans escape)
Ionization, pickup
Atmospheric sputtering: trajectories outside exobase

4. Atmosphere properties
Europa
Ganymede
Callisto
O2 (cm-2)
x 1014
(1-10) x 1014
3 x 1016 (?)
O (cm-2)
< 1013
(?)
CO2 (cm-2)
8 x 1014
Na (cm-2)
4 x 109 (5 RE)
< 108 (3-6 RG)
H (cm-2)
2.4 x 1012
Ionosphere
≤ 104 cm-3
(need illumination of trailing hemisph)
~102 cm-3
2 x 104 cm-3
Atmospheres & ionospheres highly variable
Self-regulation: enhanced neutral densities lead to larger ionosphere densities, hence stronger currents & reduced ionospheric E-field; increases shielding & reduces sputtering

5. Europa
Kliore et al. (1997)

6. Ganymede
Eviatar et al. (2001)

7. Callisto
Kliore et al. (2002)

8. Approaches for simulating plasma environment and atmospheres
Analytical solutions not possible
Atmospheres: Monte Carlo codes
Plasma & magnetic environment: MHD and Hybrid models
Atmosphere-magnetosphere interaction: Monte Carlo model combined with fixed B field

9. Moon atmosphere models
Europa:
Ip (1996): Europa O2 exosphere model
Saur et al. (1998): neutral atmosphere and plasma interaction model for Europa
Kabin et al. (1999)
Liu et al. (2000)
Shematovich and Johnson (2001): 1D Monte Carlo Europa oxygen model
Smyth and Marconi (2006) (2D Monte Carlo model)

10. Moon atmosphere models
Callisto
Liang et al. (2005)
Ganymede
Yung and McElroy (1977)
Purves and Pilcher (1980)
Wong et al. (1999) (2D)
Marconi (2007) (Multi-species, 2D)

11. Atmosphere-Magnetosphere Models
Ganymede:
Stone and Armstrong (2001) (MHD)
Kopp and Ip (2002) (MHD)
Paty and Winglee (2004) (Multi-fluid)
Europa:
Saur et al. (1998)
Kabin et al. (1999)
Liu et al. (2000)
Zimmer et al. (2000)
Schilling et al. (2007)

12. Other models
Mercury magnetosphere hybrid model (Trávnícek et al., 2009)
Enceladus, Titan?

13. Needs for RPWI
Engineering models for moon neutral atmosphere and ionosphere densities
Average B field engineering model describing vicinity of Galilean moons
E field model
Software for interfacing simulated RPWI with atmosphere & plasma environment models
Any more?