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Verification of Electron Beam Irradiation as a Lipid Decontamination Method for Life Detection Instrumentation
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  • Denise Buckner,
  • Mary Beth Wilhelm,
  • Michael Gaffey,
  • Antonio Ricco,
  • Margaret Abraham
Denise Buckner
Blue Marble Space Institute of Science

Corresponding Author:[email protected]

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Mary Beth Wilhelm
NASA Ames Research Center
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Michael Gaffey
University of North Dakota
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Antonio Ricco
NASA Ames Research Center
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Margaret Abraham
Aerospace Corporation Pasadena
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Lipids are key targets for current, proposed, and future life detection missions to both rocky and icy worlds. With the high accuracy and low limit of detection (LoD) required by many new and future instruments (sub ~ppb range), decontamination of life detection hardware, particularly components that handle or process planetary samples in situ, is necessary to prevent false positives. Lipids are a biosignature of interest as they are ubiquitous to all life as we know it, can survive in the geologic record for an order of magnitude longer than any other biomolecule (i.e. billions of years), and are able to form through both biotic and abiotic processes. Traditional NASA contamination control (CC) for life detection instruments primarily focuses on hardware fabrication in sterile cleanroom environments, killing of microbes, and flushing/mechanically removing contaminants off instrument and spacecraft components. However, recent studies suggest that standard cleaning methods are unlikely to sufficiently remove lipid contaminants to meet instrument LoD. These include NASA-approved methods for Planetary Protection (PP) (e.g., dry heat microbial reduction and vapor phase H2O2) and cleanroom decontamination methods (e.g., protective clothing, HEPA air filtration, surface cleaning with detergents/water/isopropyl alcohol, autoclave, ethylene oxide treatment). Effective laboratory standard decontamination methods (ashing at 550° C, chlorinated solvent flushes) are efficient at eliminating lipid contamination, but are often incompatible with sensitive materials required in the construction of life detection instrument components. We will present the results of a study to determine the efficiency of lipid decontamination using a “nontraditional” CC method, Electron Beam Irradiation (EBI), that would be compatible with common major instrument materials used in life detection instrumentation. Percent lipid reduction following EBI application will be compared to percent reduction following treatment with traditional NASA PP methods, using standards from four classes of lipid molecules that are proposed targets of life detection instrumentation.