EFFECTS FROM LARGE SOLAR PROTON EVENTS ON PERFORMANCE OF SPACE SOLAR ARRAYS IN GEOSTATIONATY ORBIT ENVIRONMENT

摘要

This paper contains an analysis of the radiation-induced degradation of silicon-based solar arrays on board of the SESAT (Siberia-Europe satellite) and the YAMAL commercial telecommunications spacecraft, launched into the geostationary Earth orbit on April 18, 2000 and September 6, 1999 respectively and currently continuing their operational service. A comparative study of the forecasted and the observed behavior of the current generated by both solar arrays given in this work has revealed a significant impact on their performance caused by the large solar flares registered during July 14-15 and November 8-9, 2000. Basing on such information as duration, scale and spectral composition of the proton flux, registered during these solar flares, the value of radiation―induced degradation of the solar arrays was assessed. As was shown by calculations, in terms of the equivalent flux of 1 MeV ― electron the impact from a single proton flare of July 14-15, 2000 was equivalent to the flux of 3.5 x 10~(13) cm~(-2,) which exceeded the annual equivalent flux of protons and electrons which had been forecasted for these two spacecraft. Results of this assessment were corroborated by the downlinked telemetry data indicating observed changes in the current generated by the space solar arrays.