Detailed investigation of spacecraft glow.

摘要

The phenomenon of spacecraft glow is simulated in detail, using a three-step procedure. The goals of the study are defined.; Characteristics of the glow phenomenon are described. The experimental behavior of glow observed around several orbital vehicles and in ground-based laboratory experiments is described. Emissions from electrically-excited nitrogen dioxide is identified as the source of the glow. Examples of typical glow spectra are presented. An overview of the atmospheric characteristics at relevant altitudes is included.; The direct simulation Monte Carlo (DSMC) technique is described and resolution difficulties in simulating rare species and events are noted. Common approaches to overcoming resolution problems are outlined. The DSMC overlay technique is described along with its benefits and limitations. Specific attention is given to the accurate inclusion of rare chemical events.; The set of surface events to be simulated is defined and is described in differential form. A Runge-Kutta method is employed to solve the resulting differential equations. Modifications to the method to account for satellite rotation are described. A steady-state analysis of the system of equations is performed. The flux of emitted, excited nitrogen dioxide is calculated. An analytical model is used to calculate the brightness of glow based on this emitted flux.; Results from each stage of the solution procedure are analyzed. The flow field results are found to be typical of rarefied, hypersonic flow. The extreme non-equilibrium behavior of the flow is captured. The importance of chemical production at the lower altitudes is shown. A dependence of the surface concentrations on both the total and relative incident fluxes is observed. Critical surface events are identified via a sensitivity study. Comparison of the variation of glow brightness with experimental results is favorable. The trend is for the simulated results to overpredict the brightness. The agreement is poorer at the upper altitudes, due to greater uncertainties in the initial conditions. The importance of the ambient density of nitric oxide is shown.