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Record Details

Record 95 of 2276
Radio Sounding Techniques for the Galilean Icy Moons and their Jovian Magnetospheric Environment
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Author and Affiliation:
Green, James L.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Markus, Thursten(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Fung, Shing F.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Benson, Robert F.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Reinich, Bodo W.(Massachusetts Univ., Center for Atmospheric Research, Lowell, MA, United States)
Song, Paul(Massachusetts Univ., Center for Atmospheric Research, Lowell, MA, United States)
Gogineni, S. Prasad(Kansas Univ., Information and Telecommunication Technology Center, Lawrence, KS, United States)
Cooper, John F.(Raytheon Technical Services Co., Greenbelt, MD, United States)
Taylor, William W. L.(QSS Group, Inc., Greenbelt, MD, United States)
Garcia, Leonard(QSS Group, Inc., Greenbelt, MD, United States) Show more authors
Abstract: Radio sounding of the Earth's topside ionosphere and magnetosphere is a proven technique from geospace missions such as the International Satellites for Ionospheric Studies (ISIS) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Application of this technique to Jupiter's icy moons and the surrounding Jovian magnetosphere will provide unique remote sensing observations of the plasma and magnetic field environments and the subsurface conductivities, of Europa, Ganymede, and Callisto. Spatial structures of ionospheric plasma above the surfaces of the moons vary in response to magnetic-field perturbations from (1) magnetospheric plasma flows, (2) ionospheric currents from ionization of sputtered surface material, and (3) induced electric currents in salty subsurface oceans and from the plasma flows and ionospheric currents themselves. Radio sounding from 3 kHz to 10 MHz can provide the global electron densities necessary for the extraction of the oceanic current signals and supplements in-situ plasma and magnetic field measurements. While radio sounding requires high transmitter power for subsurface sounding, little power is needed to probe the electron density and magnetic field intensity near the spacecraft. For subsurface sounding, reflections occur at changes in the dielectric index, e.g., at the interfaces between two different phases of water or between water and soil. Variations in sub-surface conductivity of the icy moons can be investigated by radio sounding in the frequency range from 10 MHz to 50 MHz, allowing the determination of the presence of density and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts. The detection of subsurface oceans underneath the icy crusts of the Jovian moons is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. Preliminary modeling results show that return signals are clearly distinguishable be&een an ice crust with a thickness of 7 km on 1) an ocean and 2) a layer of bedrock. Knowledge of the ionospheric contributions to the time delay of the low-frequency subsurface radar is shown to be important in obtaining accurate depth information.
Publication Date: Sep 13, 2004
Document ID:
20040171687
(Acquired Dec 03, 2004)
Subject Category: GEOPHYSICS
Document Type: Preprint
Contract/Grant/Task Num: NASW-02037; NASW-99029; NAG5-11792; WBS 51-973-80-60
Financial Sponsor: NASA; Washington, DC, United States
NASA Goddard Space Flight Center; Greenbelt, MD, United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 43p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution under U.S. Government purpose rights
NASA Terms: JUPITER SATELLITES; GEOPHYSICS; GALILEAN SATELLITES; RADIOSONDES; MAGNETOSPHERES; GANYMEDE; ISIS SATELLITES; IMAGE SATELLITE; ELECTRIC FIELDS; GROUND PENETRATING RADAR; CALLISTO; EUROPA; EARTH IONOSPHERE
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