A Simple Model of the Effect of Solar Array Orientation on SMART-1 Floating Potential

Results from SMART-1 plasma measurements indicate that the spacecraft is, in general, floating 10 to 30 V negative with respect to the ambient plasma and that the floating potential varies with the orientation of the solar array with respect to the direction of the thrust. It is shown in this paper that a wake created behind the solar panel by the plasma generated in the plume by charge exchange and expanding toward the spacecraft may explain such a potential variation.