Changes of contamination deposition on spacecraft surface and evaluation of control factors

After spacecraft launched into space environment, molecule contamination and tiny particle contamination deposit on spacecraft surface and constitute the surface contamination layer. This contamination phenomenon has different levels of negative impacts on some technical systems. The on-orbit detection results of spacecraft surface contamination both in China and abroad were discussed. Surface contamination deposition changes and control factors were preliminarily evaluated. The result shows that deposition changes of surface contamination within the first 1 to 2 years after launch are controlled by the spacecraft outgassing mass by itself, outgassing rate, spacecraft surface temperature and air flow direction. The deposition mass within early period is larger, which is controlled by more surface outgassing by spacecraft itself within early period and higher deposition rate after launch. And the deposition mass is more in the ram area than in the yield area. The surface deposition in the later period shows obvious drop or slow fluctuations, and possesses omnidirectional characteristics. Some control factors with omnidirectional effect were discussed, among which high-energy particle flux and solar ultraviolet radiation flux may be the main control factors.