Contamination Monitoring During The Hubble Space Telescope Thermal Vacuum / Thermal Balance Test

Abstract

A comprehensive contamination control program was developed and implemented at LMSC for the Hubble Space Telescope (HST) Thermal Vacuum Test. The test program involved monitoring HST sensitive optical systems using both active (realtime) and passive molecular contamin-ation samples. Data and test conditions were monitored realtime to assure that molecular contamination accumulation would not threaten the telescope primary optics. The contamina-tion control program utilized six Temperature-controlled Quartz Crystal Microbalance (TQCM) sensors, nine magnesium fluoride-coated aluminum over glass optical witness samples (OWS), and particulate and nonvolatile residue (NVR) fallout samples. The program utilized wit-ness samples which were baselined before and analyzed after the vacuum test to characterize the particulate contamination levels and optics reflectance changes induced by the thermal vacuum environment. This paper describes the instrumentation and active and passive monitoring techniques used for the HST Thermal Vacuum Test as well as the contamination results and analyses. Rationale for selection of the sampling methods and locations relative to the spacecraft surfaces is included.