Evolution of secondary electron emission characteristics of spacecraft surfaces

The secondary electron emission (SEE) characterization of spacecraft materials, subjected to varying degrees and type of surface contamination to which operating spacecraft might realistically be subjected, is described. The dynamic evolution of secondary electron yields resulting from energetic electron and ion bombardment of surfaces within a rarefield atmosphere representative of the microenvironment surrounding space vehicles is investigated. The changes in the SEE characteristics of the surfaces leads to significant underestimation of the charging levels to which a particular vehicle may be subjected to a variety of environmental conditions.