14:30 〜 14:45
[PPS01-16] Ray Tracing for Titan’s Ionospheric Occultation of Saturn Radio Emissions: Implications for JUICE Mission
キーワード：土星、氷衛星、JUICE、電波、電離圏
Titan has an ionosphere with complex variations due to solar radiation and interactions with Saturn's magnetosphere. Previous studies have investigated Titan's electron density using methods such as radio occultation and in situ measurements (Garand et al., 2014; Chatain et al., 2021a, 2021b). Additional constraints on electron density are required for more detailed investigations.
In Yasuda et al. (2024), a new technique was developed to measure the electron densities of moons' ionospheres using planetary auroral radio emissions. This technique was successfully applied to the Galileo PWS data of Jovian radio waves, revealing new insights into the electron densities and formation processes of the ionospheres of Ganymede and Callisto, both of which have tenuous neutral atmospheres.
To extend this method using radio emissions from other planets or to adapt it for moons with dense atmospheres, we applied it to the Cassini RPWS data to derive Titan's ionospheric electron density. Our results demonstrate that Saturn’s radio emissions are refracted by Titan’s ionosphere, allowing us to measure the ionospheric electron density from radio data. We also present the derived electron density profiles of Titan's ionosphere during the Cassini Titan 15 flyby.
The Cassini RPWS observations provide the closest analog to the JUICE RPWI observations, which will provide not only the flux but also polarization measurements of the radio waves surrounding the outer planets' icy moons. Polarization measurements are crucial as they help constrain the location of radio sources and the total electron content of Saturn’s radio emissions. By applying our method to Cassini data, we can gain new insights that will contribute to future studies of icy moon ionospheres with JUICE RPWI.
In Yasuda et al. (2024), a new technique was developed to measure the electron densities of moons' ionospheres using planetary auroral radio emissions. This technique was successfully applied to the Galileo PWS data of Jovian radio waves, revealing new insights into the electron densities and formation processes of the ionospheres of Ganymede and Callisto, both of which have tenuous neutral atmospheres.
To extend this method using radio emissions from other planets or to adapt it for moons with dense atmospheres, we applied it to the Cassini RPWS data to derive Titan's ionospheric electron density. Our results demonstrate that Saturn’s radio emissions are refracted by Titan’s ionosphere, allowing us to measure the ionospheric electron density from radio data. We also present the derived electron density profiles of Titan's ionosphere during the Cassini Titan 15 flyby.
The Cassini RPWS observations provide the closest analog to the JUICE RPWI observations, which will provide not only the flux but also polarization measurements of the radio waves surrounding the outer planets' icy moons. Polarization measurements are crucial as they help constrain the location of radio sources and the total electron content of Saturn’s radio emissions. By applying our method to Cassini data, we can gain new insights that will contribute to future studies of icy moon ionospheres with JUICE RPWI.