Cassini's floating potential in Titan's ionosphere: 3-D particle-in-cell simulations

Accurate determination of Cassini’s spacecraft potential in Titan’s ionosphere is important for interpreting measurements by its low energy plasma instruments. Estimates of the floating potential varied significantly, however, between the various different plasma instruments. In this study we utilize 3-D particle-in-cell simulations to understand the key features of Cassini’s plasma interaction in Titan’s ionosphere. The spacecraft is observed to charge to negative potentials for all scenarios considered, and close agreement is found between the current onto the simulated Langmuir Probe and that observed in Titan’s ionosphere. These simulations are therefore shown to provide a viable technique for modeling spacecraft interacting with Titan’s dusty ionosphere

Saturn’s near-equatorial ionospheric conductivities from in situ measurements

Cassini’s Grand Finale orbits provided for the first time in-situ measurements of Saturn’s topside ionosphere. We present the Pedersen and Hall conductivities of the top near-equatorial dayside ionosphere, derived from the in-situ measurements by the Cassini Radio and Wave Plasma Science Langmuir Probe, the Ion and Neutral Mass Spectrometer and the fluxgate magnetometer. The Pedersen and Hall conductivities are constrained to at least 10⁻⁵–10⁻⁴ S/m at (or close to) the ionospheric peak, a factor 10–100 higher than estimated previously. We show that this is due to the presence of dusty plasma in the near-equatorial ionosphere. We also show the conductive ionospheric region to be extensive, with thickness of 300–800 km. Furthermore, our results suggest a temporal variation (decrease) of the plasma densities, mean ion masses and consequently the conductivities from orbit 288 to 292

Manifestations of Culture in Website Design

The web is a global phenomenon and its reach and influence ignores political and cultural boundaries. However, the web’s global presence and easy accessibility does not also mean there are no issues related to the understanding and interpretations of its content. Of particular interest to us is to find out whether there is any effect of culture on web design. In this paper, we report on our research into the identification of elements that can be attributed to culture on website design. We examined and compared South Korean and UK’s charity websites and identified these elements of the websites. The findings suggest that there are some differences and preferences in the website design that are mostly related to whether the websites employ multimedia and provide facilities for user input. <!--EndFragment--

Titan conductivities (Cassini)

This is the dataset for the article &quot;Conductivities of Titan&apos;s dusty ionosphere&quot;, Journal of Geophysical Research: Space Physics, DOI: 10.1029/2021JA029910Please see the article for the description and references for data derivations.ephemerides.xlsx contents (one flyby per sheet):UTC time stampaltitude [km] altitude above Titan surfacesc_Velocity [km/s] magnitude of Cassini spacecraft velocitySolar_Zenith_Angle [degrees] angle from the Sun direction (X-axis in solar ecliptic coordinates)sub_solar_lat [degrees] of sub-solar latitude (i.e. Titan geographic latitude where Sun is in zenith)Saturn_Local_time [hours] azimuthal coordinate of Cassini with respect to SaturnLocal_Time [hours] azimuthal coordinate of Cassini with respect to TitanLat [degrees] Titan geographic latitudeWest_Long [degrees] Titan geographic longitude, counted westwardRx_ecl_km, Ry_ecl_km, Rz_ecl_km [km] Titan-centered solar ecliptic coordinates of Cassini (X-axis towards Sun, Z-axis is the component of Titan angular rotation vector orthogonal to X, Y-axis completes right-handed set)input_data.xlsx contents (one flyby per sheet)% &lt;variable&gt;_err is the 2-sigma uncertainty in the same units as the variableUTC time stampN2 [cm^-3] molecular nitrogen number densityCH4 [cm^-3] methane number densityNe [cm^-3] electron charge densityNi [cm^-3] positive ion charge densityZN [cm^-3] negative dust charge number densityTe [K] electron temperatureTi [K] positive ion temperatureTd [K] negative dust temperatureZd mean negative dust charge numberMi [amu] mean positive ion massMd [amu] mean negative ion massB [T] magnetic fieldconductivities.xlsx contents (one flyby per sheet):% &lt;variable&gt;_err is the 2-sigma uncertainty in the same units as the variableUTC time stampnyElectrons [s^-1] total electron momentum transfer collision frequencynyIons [s^-1] total positive ion momentum transfer collision frequencynyDust [s^-1] total negative dust momentum transfer collision frequencysig_Parallel [S/m] field-parallel conductivitysig_Pedersen [S/m] Pedersen conductivitysig_Hall [S/m] Hall conductivitycasesl.xlsx contents (one time stamp per sheet):% &lt;variable&gt;_err is the 2-sigma uncertainty in the same units as the variableUTC time stampaltitude [km] altitude above Titan surfaceZd mean negative dust charge numbersig_Par [S/m] field-parallel conductivity for given Zdsig_P [S/m] Pedersen conductivity for given Zdsig_H [S/m] Hall conductivity for given Zdmi_spec [amu] positive ion mass spectra (INMS &amp; IBS combined)Ni_spec [cm^-3] positive ion charge density as a function of massmd_spec [amu] negative dust/ion mass spectra (ELS)Nd_spec [cm^-3] negative dust/ion charge density as a function of mas

Titan conductivities (Cassini)

This is the dataset for the article &quot;Conductivities of Titan&apos;s dusty ionosphere&quot;, Journal of Geophysical Research: Space Physics, DOI: 10.1029/2021JA029910Please see the article for the description and references for data derivations.ephemerides.xlsx contents (one flyby per sheet):UTC time stampaltitude [km] altitude above Titan surfacesc_Velocity [km/s] magnitude of Cassini spacecraft velocitySolar_Zenith_Angle [degrees] angle from the Sun direction (X-axis in solar ecliptic coordinates)sub_solar_lat [degrees] of sub-solar latitude (i.e. Titan geographic latitude where Sun is in zenith)Saturn_Local_time [hours] azimuthal coordinate of Cassini with respect to SaturnLocal_Time [hours] azimuthal coordinate of Cassini with respect to TitanLat [degrees] Titan geographic latitudeWest_Long [degrees] Titan geographic longitude, counted westwardRx_ecl_km, Ry_ecl_km, Rz_ecl_km [km] Titan-centered solar ecliptic coordinates of Cassini (X-axis towards Sun, Z-axis is the component of Titan angular rotation vector orthogonal to X, Y-axis completes right-handed set)input_data.xlsx contents (one flyby per sheet)% &lt;variable&gt;_err is the 2-sigma uncertainty in the same units as the variableUTC time stampN2 [cm^-3] molecular nitrogen number densityCH4 [cm^-3] methane number densityNe [cm^-3] electron charge densityNi [cm^-3] positive ion charge densityZN [cm^-3] negative dust charge number densityTe [K] electron temperatureTi [K] positive ion temperatureTd [K] negative dust temperatureZd mean negative dust charge numberMi [amu] mean positive ion massMd [amu] mean negative ion massB [T] magnetic fieldconductivities.xlsx contents (one flyby per sheet):% &lt;variable&gt;_err is the 2-sigma uncertainty in the same units as the variableUTC time stampnyElectrons [s^-1] total electron momentum transfer collision frequencynyIons [s^-1] total positive ion momentum transfer collision frequencynyDust [s^-1] total negative dust momentum transfer collision frequencysig_Parallel [S/m] field-parallel conductivitysig_Pedersen [S/m] Pedersen conductivitysig_Hall [S/m] Hall conductivitycasesl.xlsx contents (one time stamp per sheet):% &lt;variable&gt;_err is the 2-sigma uncertainty in the same units as the variableUTC time stampaltitude [km] altitude above Titan surfaceZd mean negative dust charge numbersig_Par [S/m] field-parallel conductivity for given Zdsig_P [S/m] Pedersen conductivity for given Zdsig_H [S/m] Hall conductivity for given Zdmi_spec [amu] positive ion mass spectra (INMS &amp; IBS combined)Ni_spec [cm^-3] positive ion charge density as a function of massmd_spec [amu] negative dust/ion mass spectra (ELS)Nd_spec [cm^-3] negative dust/ion charge density as a function of massTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

PIC simulation data of Cassini during the grand finale

This is the simulation data used in the publication Zhang et al. (2021): Particle-In-Cell Simulations of the Cassini Spacecraft's Interaction with Saturn's Ionosphere during the Grand Finale. This article was accepted on 8th March 2021, and full details on these simulations can be found in this article

Discovery of Alfven waves planetward of the Rings of Saturn

Between April and September 2017 in the final stages of the Cassini Saturn Orbiter mission the spacecraft executed 22 orbits passing planetward of the innermost ring, the D-ring. During periapsis passes on all these orbits oscillations were detected in the azimuthal magnetic field components on typical time scales from a few minutes to 10 minutes. We argue that the time-varying signals detected on the spacecraft are also primarily time-varying in the plasma frame. Nonetheless, we show that nearly all signals exhibit a distinct spatial effect, namely a magnetic node near the effective field line equator. The oscillations thus have a standing structure along the background magnetic field and it follows that they are field line resonances associated with Alfvén waves. The form of the signals suggests that the local field line resonances are most likely pumped from global sources. This is the first detection in a giant planet magnetosphere of a phenomenon known to be important at Earth