Modeling of spacecraft rarefied environments using a proposed surface model

The modeling of spacecraft glow surrounding a small clean satellite is discussed. A direct simulation Monte Carlo (DSMC) technique was used to model the flowfield and included both surface and gas-phase chemical reactions. It has been suggested that emission from excited NO₂ molecules produces the spacecraft glow. The DSMC calculations included chemical reactions in the flowfield to produce NO, as well as surface chemical reactions to generate the NO₂. The orbit-dependent optical radiation was calculated and compared with data from the Atmosphere Explorer experiment over the 140-200-km altitude range. The results show that the surface model can account for the observed data in magnitude and altitude dependence for suitable choices of the surface heat of absorption and freestream NO concentration.