CONTAMINATION ANALYSIS OF DEEP IMPACT INSTRUMENTS

摘要

On the evening of July 3, 2005, Deep Impact, built by Ball Aerospace & Technologies Corp forrnone of NASA's Discovery Missions, rendezvoused with comet 9P/Tempel 1. Following thernspacecraft impactor module's launch into the comet nucleus, onboard visible and IR instrumentsrnwere used to monitor newly exposed surfaces at the crater site. The instruments had the criticalrnfunction of guiding the impactor onto a collision course with the comet, while taking sciencerndata before, during, and after the impact. Post-encounter data gathered from the instruments hasrnprovided a wealth of information that continues to reveal great details of the chemicalrncomposition of 9P/Tempel 1(1). Contributing to the success of this mission are the instrumentrncontamination analyses and design mitigations that were implemented to ensure opticalrnthroughput performance. This includes simulation and assessment of water transport into therncryogenic HRI instrument during the on-orbit graphite composite telescope outgassing phase andrnof the outgassing and transport of organic contamination from coatings and adhesives. Effects onrnoptical throughput and IR detector performance are discussed. Diffusion outgassing rates of nonmetallicsrnand non-volatile residue (NVR) surface desorption are modeled as a function ofrnchanging orbital thermal profile. Analysis theory, setup and results are discussed and designrnmitigations are reviewed.