Effects of Atomic Oxygen on the Vacuum-Induced Mass Loss Properties of a Variety of Spacecraft Materials

The space environment influences spacecraft design and material selection in many ways. Two aspects of the space environment that were of interest for this research are the vacuum and atomic oxygen (AO) environments. This project used the outgassing testing chamber and the AO chamber in the Cal Poly Space Environments lab to test multiple common spacecraft materials and determine whether AO affects the outgassing properties of those materials. This research has relevant applications in the design and material selection for spacecraft in low-Earth orbits. AO and outgassing are both known to be individual contributors of spacecraft material mass loss and degradation, but laboratory tests on the synergy are rare. ASTM E595 standardized test procedures were used to determine the Total Mass Loss (TML) and Collected Volatile Condensable Materials (CVCM) values for each material, at which point the test group of materials were subjected to AO exposure according to ASTM E2089 while the control group remained under similar vacuum and temperature conditions. Finally, all of the materials were subjected to a second ASTM E595 test. The results show a statistically significant effect of AO on some materials\u27 outgassing properties. In particular, three of the four silicone materials tested showed a lower TML for the AO exposed group compared to the control group which can be explained by the glassification of silicone due to AO exposure. This explanation was confirmed by Fourier Transform Infrared (FTIR) spectroscopy. More testing is recommended to confirm the trends found during the testing and to re-test the materials whose wide variation in outgassing values prevented conclusions from being drawn