Gassing processes during space simulation and thermal vacuum testing of spacecraft

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Gassing processes during space simulation and thermal vacuum testing of spacecraft

Nuss, H.E. / Streuff, I.

Vacuum conditions, outgassing of test article's materials and desorbing gas loads from spacecraft or test facility during thermal testing can have an essential impact on the thermal balance conditions, potential contamination processes und functional performance of specific spacecraft components or experiments. For the medium size (some 50 m³ volume) and the large thermal testing facility (some 500 m³ volume) of IABG (Industrieanlagen-Betriebsgesellschaft) measurements of the outgassing rate have been performed for dry runs and for satellite thermal tests. By pressure rise measurements the gassing rate for the facilities and their time dependence were determined. The data show that the processes include diffusion and desorption processes, and indicate a leak rate determination method. In addition to gassing rates and their impact on optimization of the pumpdown procedure and of the available He refrigerator cryopump pumping capacity, the desorption and outgassing from inner spacecraft surfaces and the resulting inner volume pressure are important with respesct to functional performance of spacecraft experiments and components.