Thin Current Sheets in the Magnetotail at Lunar Distances: Statistics of ARTEMIS Observations

The magnetotail current sheet's (CSs) spatial configuration and stability control the onset of magnetic reconnection - the driving process for magnetospheric substorms. The near-Earth CS has been thoroughly investigated by numerous missions, whereas the midtail CS has not been adequately explored. This is especially the case for the long-term variation of its configuration in response to the solar wind. We present a statistical analysis of 1261 magnetotail CS crossings by the Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) mission orbiting the moon (X similar to -60 RE), collected during the entirety of Solar Cycle 24. We demonstrate that the magnetotail CS typically remains extremely thin, with a characteristic thickness comparable to the thermal ion gyroradius, even at large distances from Earth's dipole. We also find that a substantial fraction (similar to one quarter) of the observed CSs have a partially force-free magnetic field configuration, with a significant contribution of the magnetic field shear component to the pressure balance. Further, we quantify the impact of the changing solar wind driving conditions on the properties of the midtail around the lunar orbit. During active solar wind driving conditions, we observe an increase in the occurrence rate of thin CSs, whereas quiet solar wind driving conditions seem to favor the formation of partially force-free CSs. We present a statistical analysis of magnetotail current sheets (CSs) collected by the ARTEMIS mission during 11 years of observations at similar to 60RE downtail We observe a large population (similar to 56%) of ion-kinetic scale CSs and a smaller population of partially force-free CSs (similar to 24%) We discuss the relationship between CS properties and solar wind driving conditions