Modeling International Space Station (ISS) Floating Potentials

The floating potential of the International Space Station (ISS) as a function of the electron current collection of its high voltage solar array panels is derived analytically. Based on Floating Potential Probe (FPP) measurements of the ISS potential and ambient plasma characteristics, it is shown that the ISS floating potential is a strong function of the electron temperature of the surrounding plasma. While the ISS floating potential has so far not attained the pre-flight predicted highly negative values, it is shown that for future mission builds, ISS must continue to provide two-fault tolerant arc-hazard protection for astronauts on EVA.