HR: 1330h
AN: SM42C-0613    [PDF]
TI: Spacecraft Charging Specification Using Model Environments
AU: * Hilmer, R V
EM: Robert.Hilmer@Hanscom.af.mil
AF: Air Force Research Laboratory/ Space Vehicles Directorate, AFRL/VSBXR, 29 Randolph Rd, Hanscom AFB, MA 01731 United States
AU: Cooke, D L
EM: David.Cooke@Hanscom.af.mil
AF: Air Force Research Laboratory/ Space Vehicles Directorate, AFRL/VSBXR, 29 Randolph Rd, Hanscom AFB, MA 01731 United States
AB: The specification and prediction of spacecraft charging at geosynchronous orbit represents an important goal of space weather research. While significant correlations exist between geomagnetic indices and the occurrence of satellite frame charging, for example with sunlit frame charging of the DSCS III satellite [Krause et al., IEEE Trans. Nucl. Sci., 47(6), 2000], the relationships are inadequate for useful predictions of charging at specific locations. Charged particles drift across the geosynchronous orbital path, and not along it, so spacecraft within less than an hour in local time experience completely different charging conditions. To account for these differences, a simple geosynchronous spacecraft surface charging application is driven using particle environments from the Magnetospheric Specification Model (MSM). Preliminary analysis using the NASCAP spacecraft-plasma interaction code indicated that spacecraft geometry and materials are responsible for the partial suppression of photoelectrons leading to frequent daylight charging of the DSCS III B-7 spacecraft. Analysis of the minimal spacecraft approximation we employ, i.e., a sunlit kapton sphere, also indicates that this so-called bootstrap charging phenomena is active. Surface charging is therefore identified by the net electron current to the kapton spacecraft determined by integrating electron, proton, and oxygen fluxes from the MSM along with secondary and backscatter yields specified as a function of energy. Spacecraft frame charging measurements from the Charge Control System on board the DSCS III satellite are compared with results obtained from the MSM-driven charging model. MSM/charging algorithm simulation output will be characterized at all local times in an effort to evaluate the model's potential effectiveness as a practical spacecraft charging specification tool.
DE: 2722 Forecasting
DE: 2764 Plasma sheet
DE: 7855 Spacecraft sheaths, wakes, charging
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting