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Electrical Sounding on Ganymede

[nasa.gov]. Electrical Sounding on Ganymede. A. Przyklenk , A. Hördt IGEP TU Braunschweig Ganymede Lander Colloquium and Workshop. 06. March 2013 | Electrical Sounding on Ganymede. Motivation. Open q uestions : Composition of Ganymede‘s subsurface ? Which non- ice materials occur ?

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Electrical Sounding on Ganymede

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  1. [nasa.gov] Electrical Sounding on Ganymede A. Przyklenk, A. Hördt IGEP TU Braunschweig Ganymede Lander Colloquium and Workshop 06. March 2013 | Electrical Sounding on Ganymede

  2. Motivation Open questions: • CompositionofGanymede‘ssubsurface? • Which non-icematerialsoccur? • Isthere a regolithlayer? [modified after Placky, 1988] 06. March 2013 | Electrical Sounding on Ganymede | 2

  3. Motivation Open Questions: • CompositionofGanymede‘ssubsurface? • Which non-icematerialsoccur? • Isthere a regolithlayer? Measurement ofelectricalparameters with ERIC (Electrical Resistivity Imaging via Capacitive Electrodes) [Kuras, 2002] 06. March 2013 | Electrical Sounding on Ganymede | 3

  4. Outline • Motivation • Quadrupole anditsimpedance • ERIC • Operating Modes • Measurements on Earth • Integration on a Lander • Conclusion 06. March 2013 | Electrical Sounding on Ganymede | 4

  5. Quadrupole and its impedance A A V V c c c c [after Kuras, 2002] 06. March 2013 | Electrical Sounding on Ganymede | 5

  6. Quadrupole and its impedance A A V V c c c c [after Kuras, 2002] 06. March 2013 | Electrical Sounding on Ganymede | 6

  7. Quadrupole and its impedance 4-Point-Array over a half-space: • Sensitivityranges displacement current → ε ρcrit conduction current → ρ 06. March 2013 | Electrical Sounding on Ganymede | 7

  8. Operating Modes Main Mode: • ImpedanceZ • 4 electrodearray • Soundingdepth: arraysize A V c c c c 06. March 2013 | Electrical Sounding on Ganymede | 8

  9. Operating Modes Potential option 1: • Contactimpedance ZC [Hördt et al., 2013] • 2 electrodearray • Soundingdepth: electrodesize Main Mode: • ImpedanceZ • 4 electrodearray • Soundingdepth: arraysize A A V V c c c c c c 06. March 2013 | Electrical Sounding on Ganymede | 9

  10. Operating Modes Potential option 2:combine E- and B-fieldmeasurments • Jupiter rotation: magneticfieldvariation on Ganymede • 100nT @ 10hrs • ElectromagneticimpedanceZEM • Penetration depth: 100km-scale • Deriveinformation on conductiveocean • Expectedelecticfieldsignal: 1Ωm (conductiveocean): 1µV Methodisveryattractive but 1MΩm (noocean): 1mV not testeduntillnow! 06. March 2013 | Electrical Sounding on Ganymede | 10

  11. Measurements on Earth Determiningelectricalparametersofice • Soundingdepth: • Z ~ 0.5m • ZC ~ 0.05m • ρ=1MΩm • εr=120[Sheshadri et al., 2008] Potential electrodes Receiver Transmitter Current electrodes 06. March 2013 | Electrical Sounding on Ganymede | 11

  12. Integration on a lander ConfigurationasproposedforthePhobosGrunt Mission: Main Mode: Impedancemeasurement: soundingdepth 2m V A 06. March 2013 | Electrical Sounding on Ganymede | 12

  13. Integration on a lander ConfigurationasproposedforthePhobosGrunt Mission: Potential option 1: Contactimpedancemeasurement: soundingdepth 0.2m V A 06. March 2013 | Electrical Sounding on Ganymede | 13

  14. Integration on a lander ConfigurationasproposedforthePhobosGrunt Mission: Potential option 2: Electromagneticimpedancemeasurement: soundingdepth 100km-scale + magnetometer V A 06. March 2013 | Electrical Sounding on Ganymede | 14

  15. Data processing in FPGA ADC DAC • Controlling of AD and DA conversion • Calculating of physical units • Pre-calibration • Packaging • Timing • HK processing data interface ADC power interface DAC Integration on a lander Usingexistingstructures: measuring dB/dt excitation feedback E-field measurement active stimulation 06. March 2013 | Electrical Sounding on Ganymede | 15

  16. Data processing in FPGA ADC DAC • Controlling of AD and DA conversion • Calculating of physical units • Pre-calibration • Packaging • Timing • HK processing data interface ADC power interface DAC Integration on a lander Usingexistingstructures: measuring dB/dt excitation feedback E-field measurement active stimulation 06. March 2013 | Electrical Sounding on Ganymede | 16

  17. Conclusion • ElectricalparametersareadaptedtodetermineGanymedessurface/subsurfacecomposition. • ERIC appointstransferandcontactimpedance. Combinedwiththemagnetometer also theelectromagneticimpedance. • Weareexperienced in measuring on earth. • Thereisalready a concepttointegrate ERIC on thelander (proposalforthePhobosGrunt Mission). 06. March 2013 | Electrical Sounding on Ganymede | 17

  18. Thank you for listening! • I also want to thank the for funding. 06. March 2013 | Electrical Sounding on Ganymede | 18

  19. 2. Quadrupole and its transfer impedance A A V V h c c c c [after Kuras, 2002] 06. March 2013 | Electrical Sounding on Ganymede | 19

  20. Determine permittivity

  21. Determine resistivity

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