Spacecraft Charging in the Earth's Upper Atmosphere

Phillip C. Anderson

W. B. Hanson Center for Space Sciences

University of Texas at Dallas

The electrostatic charging of a satellite in a space plasma is the result of charged particles impinging on or being ejected from the spacecraft. The resultant charge is a function of the properties of the spacecraft materials and the various sources of charged particles such as thermal electrons and ions, photoelectrons, secondary electrons, and energetic electrons of magnetospheric origin. The differential charging of satellites in Earth orbit has been the cause of a number of anomalies including complete loss of spacecraft. There are also fears of possible electrostatic discharge hazards to astronauts performing EVA (Extra-Vehicular Activities) during the construction of the International Space Station (ISS). Indeed, an instrument designed to measure the electrostatic charging on the ISS was recently installed on the space station. I will discuss the physics of spacecraft charging and the charging environments associated with the various orbital regimes, focusing primarily on low-Earth orbit. I will show charging data collected on various platforms including the ISS and the Defense Meteorological Satellite Program (DMSP) spacecraft and will discuss the modeling efforts that are being undertaken in an attempt to understand the spacecraft charging phenomena. I will also discuss the various strategies designed to mitigate the effects of spacecraft charging and protect on-orbit spacecraft and the astronauts.