Survey of International Space Station Charging Events

With the negative grounding of the 160V Photovoltaic (PV) arrays, the International Space Station (ISS) can experience varied and interesting charging events. Since August 2006, there has been a multi-probe p ackage, called the Floating Potential Measurement Unit (FPMU), availa ble to provide redundant measurements of the floating potential of th e ISS as well as the density and temperature of the local plasma environment. The FPMU has been operated during intermittent data campaigns since August 2006 and has collected over 160 days of information reg arding the charging of the ISS as it has progressed in configuration from one to three PV arrays and with various additional modules such as the European Space Agency?s Columbus laboratory and the Japan Aeros pace Exploration Agency's Kibo laboratory. This paper summarizes the charging of the ISS and the local environmental conditions that contr ibute to those charging events, both as measured by the FPMU.