In the field of contamination control, many unknowns exist. Often, contamination control engineers have to utilize multiple spectroscopic, macroscopic, and microscopic tools to identify contamination sources when there is a potential contamination exposure to space flight hardware. Understanding the chemical composition of the molecular contamination provides an opportunity for contamination control engineers to determine if this contamination is problematic or benign. In this study, an existing witness plate program for monitoring space flight hardware during the assembly, integration, and testing phases is coupled with micro Raman spectroscopy analysis. The main goal of this study is to determine the limitations, reproducibility, and throughput of micro Raman spectroscopy for characterizing molecular contamination. Micro Raman Spectroscopy will be an additional tool used by contamination control engineers to monitor the cleanliness of space flight hardware.
Contamination control engineers provide critical plans to monitor, mitigate, and reduce the impact of molecular and particulate contamination on spacecraft systems. Witness monitoring programs are dependable methods that utilize strategically placed witness samples on space flight hardware to monitor particulate and molecular contaminants during the assembly, integration, and test (AI&T) phases. Traditionally, optical characterization of these witness plates is the tool to determine the presence of molecular films on space flight hardware in the AI&T environment. Once a visual inspection or optical measurement identifies the presence of a contaminant, analysts collect tape lifts and wipe samples from the witness plate for analysis in an analytical lab with a potential contaminant identified within 24 hours. To speed up this process and reduce the impact to project schedule and cost the use of a non-invasive and in situ method for optical witness plate program with portable Raman spectroscopy to detect molecular contamination on spacecraft was explored.
KEYWORDS: Raman spectroscopy, Contamination, Space operations, Spectrometers, Chemical analysis, Luminescence, Silicon, Aluminum, System integration, Polymers
Contamination control engineers are constantly challenged by time-consuming processes during the system assembly, integration and test phase for spacecraft. Hardware components, subassemblies, and integrated systems must be visually inspected throughout the process, and any signs of contamination found are usually analyzed by processes that can take days to complete. Portable Raman spectroscopy is a promising technology for spacecraft integration, where it may be possible to probe hardware or witness surfaces and identify contaminants throughout the assembly, integration and test phase. This study explored detection of five common spacecraft contaminants with portable Raman spectroscopy: silicone, hydrocarbon, fluorocarbon, ester, and a glycol polymer. It was found portable Raman spectroscopy can provide a quick-look capability which can be followed by more detailed contaminant quantification analysis techniques. In this way, portable Raman spectroscopy can aid contamination control engineers in providing actionable information to projects earlier in the assembly, integration and test phase of the project lifecycle.
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