International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"

Auroral footprint of Ganymede is produced by electric currents generated by motion of the satellite relative Jovian magnetic field. This current flows along Jupiter's magnetic field lines and exites the glow of the upper atmosphere. This ultraviolet image of Jupiter was taken with the Hubble Space Telescope Imaging Spectrograph (STIS) on November 26, 1998.

Tenuous oxygen atmosphere of 1.2 × 10 8 –7 × 10 8 cm −3 and hydrogen atoms of ~ 1.5 × 10 4 cm −3 Intrinsic magnetic moment is about 1.3 × T·m 3 directed against the Jovian magnetic moment. 720 nT at equator (Jovian magnetic field 120 nT). Moves relative to Jovian magnetic field with subsonic velocity. Its magnetosphere has diameter is 4–5 R G (R G = 2,631.2 km) Ganymede has airglow near ± 50° latitude, which is exactly the boundary between the open and closed field lines of the Ganymedian magnetosphere Relative motion induces magnetic field that suggests highly conducting ocean. Energetic electrons and ions (tens and hundreds of kiloelectronvolts) hit Ganymede’s surface that leads to sputtering International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"

Measurements requirements International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments" Combination of internal and induced magnetic fields -> open magnetosphere

Ganymede’s surface and atmosphere Atmospheric/ion composition and its losses to the magnetosphere Fluxes of accelerated ions and electrons near Ganymede and/or at its surface. Surface sputtering and implantation of energetic ions Mapping of surface composition Jovian magnetosphere and its interaction with Ganymede Ion composition of plasma and accelerated particles Ganymede’s role in magnetospheric plasma population Magnetospheric plasma dynamics Electromagnetic interaction with Jupiter International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"

Measurements of flux and velocity distribution of suprathermal and energetic ions, and mass/charge ion composition for investigation: - influence on Ganymede’s surface - surface composition - Ganymede’s atmospheric losses - composition of Ganymede and its atmosphere - Jovian magnetospheric plasma dynamics and the role of Ganymede in Jovian magnetosphere International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"

– collimator, 2 – electrostatic analyzer, 3 – light trap, 4 – diaphragm, 5 – wedge magnet, 6 – drift tube, 7 – grids, 8 – secondary electron multiplier (SEM), 9 – DC amplifier, 10 – pulse counter Velocity distributions of proton- and α -s measurements in May International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"

Structure of the instrument: 1 – angular scanner, 2 – electrostatic analyzer, 3 – drift tube, 4 – magnet, 5 – focusing electrode, 6 – MCP detector Simulation results for solar wind ions Fe +7 - Fe +12 and O +5 and O +6 with E/Q = 1 keV (1…20 keV/Q capability) International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"

Energy range, keV/Q1…20 Mass range, M/Q2…9 Mass resolution, M/Δm10-40 for E/Q = 1 keV Full angle of view30 0 х30 0 for E/Q = 1 keV Angular resolution~2 0 Analyzer dimensions, mm230х170х120 Estimated mass, kg3.5 International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"

—Measurements of ions, electrons and secondary neutral particles provide important tools for investigation of Ganymede’s surface characteristics and composition —Ion spectrometer under development can be considered as candidate for plasma suite developed by MSSL and IKI for exploration of planetary surfaces and planetary magnetospheres International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments"