TECHNIQUE TO EVALUATE UV-INDUCED DEGRADATION OF SPACE OPTICS

OPTICAL SURFACES IN SPACECRAFT SUCH AS TELESCOPE REFLECTORS ARE KNOWN TO ACCUMULATE AN ABSORBING COATING OF CONTAMINANTSWHICH SIGNIFICANTLY REDUCES THEIR PERFORMANCE. WE NOW UNDERSTAND THIS PROCESS TO BE DUE TO UV LIGHT FROM THE SUN WHICH PHOTOLYZES ORGANIC MOLECULES FROM THE SPACECRAFT'S CONTAMINATION CLOUD. HOWEVER, NOT ENOUGH IS KNOWN ABOUT THERATES OF THE PROCESS OR ITS CHEMISTRY TO BE ABLE TO COUNTERACT THE PROCESS EITHER BY AVOIDING THE USE OF SENSITIVE MOLECULAR SUBGROUPS OR BY STIMULATING THE REMOVAL OF THE ACCUMULATED MATERIAL. IN THIS PROGRAM, WE PROPOSE TO DEVELOP THIS INFORMATION BY SIMULATING THE DAMAGE PROCESSAT A SYNCHROTRON RADIATION FACILITY IN AN EXISTING SURFACE ANALYSIS CHAMBER. WE WILL ADD THE CAPABILITY FOR DETECTING NEUTRAL FRAGMENTS WHICH EMERGE FROM THE PHOTON INDUCED REACTION, AND USE THE COMBINED SYSTEM TO DETERMINE THE REACTION CHANNELS FOR THE PHOTOCHEMICAL PROCESSES. THIS INFORMATION WILL MAKE POSSIBLE THE IDENTIFICATION OF THE MOLECULAR SUBGROUPS WHICH ARE THE PRINCIPAL CAUSE OF THE INDUCED ABSORPTION ON SPACE OPTICS. IN THIS PHASE I PROGRAM, WE PLAN TO DETERMINE THE FEASIBILITY OF OUR APPROACH BY ANALYZING THE SIGNAL AND NOISE LEVELS OF THE ALTERNATIVE METHODS FOR IONIZATION AND DETECTION OF THE NEUTRAL REACTION FRAGMENTS. IN PHASE II WE WOULD CONSTRUCT THE APPARATUS; PERFORM THE PHOTOLYSIS MEASUREMENTS; AND INTERPRET THE DATA ON THE COMPLEX LUBRICANT AND SOLVENT MOLECULES TYPICAL OF THE SPACE ENVIRONMENT IN THE LIGHT OF THE BEHAVIOR OF THEIR ISOLATED SUBGROUPS.