Operating in the space environment: A spacecraft charging study of the advanced x-ray astrophysics facility-spectroscopy spacecraft

摘要

The effects attributed to spacecraft charging can be a serious engineering concern. Scientific instruments designed to measure properties of the natural space environment may have readings that are compromised due to the buildup of electric fields around the spacecraft. Charged surfaces may attract ionized contaminants, causing an increase in surface contamination. Arc-discharging is a rapid release of large amounts of charge. These discharges can cause physical surface damage and the discharge process can generate large structural currents which, when coupled into spacecraft electronics, can cause upsets and anomalies. Arc discharging is seen as the primary means by which spacecraft operations is disturbed by spacecraft charging. The effects of spacecraft charging bring about a need for space programs to adopt a plan to evaluate the impact of spacecraft charging related effects on spacecraft operations. This plan would be, in effect, a spacecraft charging protection plan. This protection plan involves defining the natural space plasma environment to which the spacecraft will be exposed, performing analyses to determine how interactions between the environment and spacecraft will affect the mission goals and objectives, and developing engineering design guidelines for the purpose of reducing or negating spacecraft charging related effects. This study presents the results of a spacecraft charging effects protection study conducted on the Advanced X-ray Astrophysics Facility-Spectroscopy (AXAF-S) spacecraft. Charging of the AXAF-S spacecraft due to auroral region environment is modeled using the POLAR (Potential Of Large spacecraft in Auroral Regions) computer code. Charging levels of exterior surfaces and the floating potential of the spacecraft relative to the ambient plasma are determined as a function of the spacecraft design, operational configuration, and orbital conditions. Areas where large surface voltage gradients exists on the AXAF-S spacecraft are identified as possible arc-discharge sites. Results of the charging analyses are the used to develop design recommendations that will limit the effects of spacecraft charging on the AXAF-S operation.