Influence of the Solar Array s on the Floating Potential of SMART -1: Numerical Simulations

research is inves tigating this anomaly with the numerical code SmartPic. The most recent results of this investigation are presented in the present paper . They indeed show that the solar array rotation is responsible for the observed anomaly. The relative position of the s olar array, or to be more precise, of the interconnectors on the array, to the thruster plasma governs the electron current collected by the spacecraft. The variation of the available interconnector surface to collect the electron current then determines t he floating potential. SmartPic successfully predict s very similar variations of the floating potential as the measurements on -board of SMART -1. The SPEDE probes were successfully implemented and simulated. The results of the se simulation show that the difference in collected current of the two probes is due to their position on two opposite sides of the spacecraft. The one probe closer to the neutralizer is in a region of higher charge exchange number densities therefore increasing the current flux on the probe.