Far plasma wake of Titan from the RPWS observations: A case study

The Titan's plasma wake has been investigated using observations from the Radio and Plasma Wave Science (RPWS) instrument onboard the Cassini spacecraft during one Titan flyby on December 26, 2005. The Langmuir Probe and the wideband receiver suggest a strong asymmetry of the plasma wake, which is displaced from the ideal wake. Two distinct structures are identified inbound and outbound of the flyby with significantly different electron number densities (n_e). The maximum electron number density reached 14 cm^-3 on the Saturn side, connected to the sunlit ionosphere, while on the opposite side of Saturn observations indicate a density smaller than 2 cm^-3. Other derived parameters of the Langmuir probe analysis suggest also a difference in plasma composition between the two structures, where heavy and light ions dominate the Saturn and anti-Saturn side respectively. The total ion outflow is estimated at 2-7 × 10²⁵ ions/s assuming a cylindrical geometry for the plasma wake.