HR: 14:45h
AN: P43A-04    [Abstracts]
TI: Europa's Surface Composition by Measuring Pickup Ions: Model Calculations
AU: * Sittler, E C
EM: edward.c.sittler@nasa.gov
AF: NASA/Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, United States
AU: Cooper, J F
EM: john.f.cooper@nasa.gov
AF: NASA/Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, United States
AU: Hartle, R E
EM: richard.e.hartle@nasa.gov
AF: NASA/Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, United States
AU: Cassidy, T A
EM: tac2z@virginia.edu
AF: University of Virginia, Engineering Physics, Thornton Hall, Charlottesville, VA 22904, United States
AU: Johnson, R E
EM: rej@virginia.edu
AF: University of Virginia, Engineering Physics, Thornton Hall, Charlottesville, VA 22904, United States
AU: Andre, N
EM: nandre@rssd.esa.int
AF: Centre d'Etudes Spatiales des Rayonnements (CESR), 9, Avenue du Colonel Roche, BP 24346 31028, Toulouse, France
AU: Blanc, M F
EM: michel.blanc@cesr.fr
AF: ESTEC, Keplerlaan 1 - PO Box 299 - 2200 AG, Noordwijk ZH, Netherlands
AB: Using a polar orbiting spacecraft around Europa with height ~ 100 km and in situ package composed of the following instruments: 3D plasma ion composition spectrometer (3DPICS), 3D plasma electron spectrometer, hot plasma energetic particle instrument and vector magnetometer. With these on can determine Europa's surface composition in 4π steradians by measuring locally produced pickup ions. Our model calculations include Jupiter's magnetospheric interaction with Europa (see Saur et al., 1998), and a model of Europa's neutral exosphere with surface as its source term. We use measurements of Europa's surface composition from Galileo (Carlson et al., 1999) for comparison purposes. The approach is to alternate between times measuring pickup ions and times measuring plasma and magnetic field parameters along the spacecraft trajectory. By measuring the pickup ion energy, arrival direction and mass-per-charge, one can trace back in time its origin if one knows the electric field and magnetic field in 3D. In situ observations of plasma flow velocities and vector magnetic fields can be used to determine the local convective electric field (E = -VXB) along the spacecraft trajectory. Then by combining this information with models of the magnetospheric interaction with Europa one can generate 3D maps of the electric and magnetic field and compute the trajectories of the pickup ions back to their source points. The neutral exosphere model is needed to estimate production rates of pickup ions and determine if ion-neutral scattering is important. The hot plasma measurements are needed to correct for sputtering rates which can be time dependent and electron plasma observations for electron impact ionization rates. Instrument characteristics, field-of-view requirements, and modes of operation will be given. At minimum we will require the 3DPICS and vector magnetometer. Saur, J., D. F. Strobel and F. M. Neubauer, JGR, vol. 103, 19947, 1998 Carlson, R. W., R. E. Johnson and M. S. Anderson, Science, vol. 286, 97, 1999.
DE: 0406 Astrobiology and extraterrestrial materials
DE: 2732 Magnetosphere interactions with satellites and rings
DE: 6221 Europa
DE: 6297 Instruments and techniques
DE: 7807 Charged particle motion and acceleration
SC: Planetary Sciences [P]
MN: 2007 Joint Assembly