Cassini's floating potential in Titan's ionosphere: 3-D Particle-In-Cell Simulations

TL;DR

This paper uses 3-D particle-in-cell simulations to accurately model Cassini's floating potential in Titan's ionosphere, aiding interpretation of plasma measurements and understanding spacecraft charging.

Contribution

It introduces a simulation-based method to determine spacecraft potential in Titan's dusty ionosphere, improving accuracy over previous estimates.

Findings

Cassini charges to negative potentials in Titan's ionosphere

Simulation results closely match Langmuir Probe measurements

Method provides a viable approach for modeling spacecraft-plasma interactions

Abstract

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.