1 / 18

Energetic Neutral Atom Imaging of the Ganymede - Jovian Magnetosphere Interaction

Energetic Neutral Atom Imaging of the Ganymede - Jovian Magnetosphere Interaction S. Barabash 1 , Y. Futaana 1 , M. Wieser 1 , X. Jia 2 , P. Wurz 3 , P. Brandt 4 , K. Asamura 5 1 Swedish Institute of Space Physics, Kiruna, Sweden

booth
Download Presentation

Energetic Neutral Atom Imaging of the Ganymede - Jovian Magnetosphere Interaction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Energetic Neutral Atom Imaging of the Ganymede - Jovian Magnetosphere Interaction S. Barabash1, Y. Futaana1, M. Wieser1, X. Jia2 , P. Wurz3, P. Brandt4, K. Asamura5 1Swedish Institute of Space Physics, Kiruna, Sweden 2Dept. of Atmospheric, Oceanic, and Space Science, U. of Michigan, Ann Arbor, USA 3 University of Bern, Physikalisches Institut, Bern, Switzerland 4Applied Physics Laboratory, Johns Hopkins University, Laurel, USA 5Institute of Space and Astronautical Science,Sagamihara, Japan

  2. Energetic neutral atom imaging of Ganymede will be performed: Particle Environment Package (PEP), a particle sensor suite including an ENA imager, was selected to fly onboard JUICE

  3. PEP configuration (baseline) • 6 sensors selected (Core configuration) • 3 units • Combines first-ever at Jupiter energetic neutral atom imaging with in-situ 3D plasma measurements • Performs first-ever high resolution gas mass spectroscopy at icy moons to identify surface constituents • JNA: Jovian Neutrals Analyzer

  4. A0 A+ B0 A+ surface surface (B) ENA imaging concept • Energetic Neutral Atoms (ENAs) propagate unaffected by electromagnetic forces • For E >> Eesc (0.64 eV, oxygen) the gravitation bending of trajectories is negligible • ENA can be used for remote diagnostic of the region of the origin • Relevant sources: • Backscattering of precipitating ions • Sputtering of the Ganymede surface materials • ENA flux

  5. ENA imaging of the Moon. Chandrayaan-1 results ENA relative flux • Chandrayaan-1/SARA experiment showed that imaging backscattered ENAs is a new and powerful diagnostic tool to investigate plasma - surface interactions • High backscattered hydrogen flux (20% vs. < 1% expected) • Mini-magnetospheres screening-off a fraction of the solar wind is well visible on ENA images Magnetic anomaly

  6. ENA production at Ganymede • Focus on plasma - surface interaction: charge - exchange ENAs are only relevant for global imaging • Plasma at the surface • Co-rotating plasma precipitating along open field lines • Energetic particles from the rad. belts • Two main mechanisms to produce ENAs • Backscattering (H, O, S) • Sputtering (mostly H and O) • Imaging of the precipitating plasma via ENAs • Geometry of the precipitation regions: open/closed field line region • Dynamics of the precipitation • Correlation with albedo features

  7. H+ S3+ S+

  8. Sputtered ENAs (1) Sputtered yields are very high (> 10) for heavy projectiles on water ices (Baragiola et al., 2003) BUT

  9. Sputtered ENAs (2) • Spectrum of the sputtered ENA is: Thomson - Siegmund (pure metal) but with very low very binding energy (Shematovich, private communication) • Estimations of the fluxes are difficult

  10. Laboratory experiment on particle irradiation of ice (1) • To understand the sputtering and backscattering processes dedicated ice experiments on particle irradiation of H2O ices were conducted using a PEP / JNA prototype at the ion facilities at U. of Bern ENA sensor Backscattering ENA Ice block Ion beam

  11. Laboratory experiment on particle irradiation of ice (2) • Typical conditions: • “Dirty” water ice T= 150 K • Pressure 10-5 mbar • ø5mm beams H+ and O+ • Energy range from 1 keV to 43 keV • Masses analyzed: H, O, and “heavy” neutrals • ENA spectra in 9 energy bands centered at from 10 eV to 2560 eV

  12. H+ beams Backscattering Sputtering Sputtering No corrections for energy - dependent sensitivity

  13. O+ beams Recolled H Sputtered No corrections for energy - dependent sensitivity

  14. Summary of the results • Backscattered H-ENA spectrum (1 keV H+) is Maxwellian (T=290 eV). Similar to the regolith but T is 2-3 times higher. • Sputtered H-ENA spectrum (33 keV O+) is different from both Maxwellian and Thompson-Siegmuind. Cut-off at 2-3 keV much lowers than predicted 8 keV. • The backscattered coefficient 27% (similar to 19% observed from the Moon)

  15. ENA imaging of Ganymede (1)

  16. Plasma precipitation regions Jia et al., 2011, MHD - model

  17. ENA imaging of Ganymede (2)

  18. Relevance of the ENA imaging from an orbiter for lander • ENA imaging from an orbiter (JUICE): • Provide remote diagnostic of the plasma (ion) environment at the lander surface • Temporal variations and correlations with the surface properties variations measured locally at the lander • Define energy and particle inputs (fluences) to the local areas around the lander

More Related