Browsing by Author "Greene, Benjamin"
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Item High Risk Spacecraft Materials Offgassing(2024 International Conference on Environmnetal Systems, 2024-07-21) Buchanan, Vanessa; Silva, Emmanuel; Padilla, Julio; Greene, Benjamin; Reys, Ilse; Harper, SusanaNASA-STD-6001B Determination of Offgassed Products (Test 7) provides the offgassing characteristics under standardized conditions for materials and assembled articles to be located within habitable spacecraft environments. Experience with Test 7 has found certain material types above many others to be of high risk for offgassing undesirable compounds aboard spacecraft. Formaldehyde and acrolein are historically high T value offgassed components of the offgassed compound target list because they have low spacecraft maximum allowable concentration (SMAC) values assigned by the JSC Toxicology Group. Carbon disulfide, benzene, acrylonitrile, and furan are additional target compounds of concern due to their lower thresholds of toxicity as determined by the JSC Toxicology Group. Materials offgassing siloxanes are also of concern due to their degradation effects on environmental control and life support system (ECLSS) components and performance. Spacecraft materials and articles defined in this manuscript as high risk were identified after examining and condensing data for these compounds of concern from approximately 3000 tests performed over 30 years. Summaries of high risk material and article types based on highest Multi-purpose Crew Vehicle (MPCV) T values are also presented. Historical analysis shows high risk components are produced largely from test materials and articles in the general categories of electronic/powered components, foams, paints/coatings/films, adhesives/tapes, epoxy/resins, liquids/gels, Nomex� with surface treatments, markers/pens/inks, dry film lubricants, thermoplastics, hygiene items (deodorants, lip balms), and silicone rubber. These data are intended to be a resource for spacecraft materials and processes managers, designers and toxicologists. High risk materials and articles intended for use aboard spacecraft should be tested in accordance with NASA-STD-6001B Test 7.Item History of NASA's Odor Assessment (Test 6)(51st International Conference on Environmental Systems, 7/10/2022) Greene, Benjamin; Buchanan, Vanessa; Tapia Harper, SusanaNASA's Odor Assessment (Test 6) for nonmetallic materials and assembled articles for spacecraft has evolved since the Apollo program in 1966 to meet various habitable spacecraft nonmetallic programmatic requirements. The purpose of Test 6 is to determine if the odor from a material or assembled article is objectionable or revolting on an odor-characteristic scale of 0 to 4. Samples of the toxicity-screened test atmosphere from a conditioned specimen container are administered to an Odor Panel of qualified human research subject volunteers using a syringe and mask, and are assigned a scored odor characteristic of undetectable (0), barely detectable (1), easily detectable (2), objectionable (3), or revolting (4). The odor from a material or assembled article is objectionable or revolting if an average rating of 2.5 or higher is assigned by an Odor Panel. This manuscript presents the history of Test 6, beginning with the Apollo spacecraft nonmetallic materials selection guidelines and test requirements from 1966, in which tests were performed in oxygen atmospheres, and follows the odor test through Skylab, Space Shuttle, International Space Station, and Orion nonmetals testing, and acceptance requirements.Item History of NASA’s Determination of Offgassed Products (Test 7)(49th International Conference on Environmental Systems, 2019-07-07) Greene, Benjamin; Buchanan, Vanessa; Harper, Susana TapiaNASA’s Determination of Offgassed Products (Test 7) from materials and assembled articles for spaceflight has evolved since the Apollo program for over 50 years to meet various habitable spacecraft non-metallic programmatic requirements. Now mandated by NASA STD-6016A Standard Materials and Processes Requirements for Spacecraft, all nonmetallic materials used in habitable flight compartments, with the exception of ceramics, metal oxides, inorganic glasses, and materials used in sealed containers must meet the offgassing requirements in NASA-STD-6001B Test 7. This manuscript presents the history of Test 7 beginning with the Apollo spacecraft nonmetallic materials selection guidelines and test requirements in 1967, in which tests were performed in mostly oxygen atmospheres, and progressing through Skylab, Space Shuttle, International Space Station non-metals testing and acceptance requirements with milder test environments, and now imposed on Commercial Crew Transportation, Space Launch System/Project Orion programs, and other NASA-funded programs. This review of the history of Test 7 presents the reader with a perspective on the development and changes undergone since inception to the present. Related NASA standard tests (some now former, discontinued, combined, or supplemental) including Test 6 (Odor Assessment), Test 16 (Determination of Offgassed Products from Assembled Articles), and Test 12 (Total Spacecraft Cabin Offgassing) are discussed in context.Item SERFE Project Overview(51st International Conference on Environmental Systems, 7/10/2022) Westheimer, David; Campbell, Colin; Contreras-Baker, Alicia; Greene, Benjamin; Korona, Adam; Everett, ShonnNASA has been developing a new spacesuit, called the Exploration Extravehicular Mobility Unit (xEMU) for over a decade. This spacesuit is underdevelopment to support missions to the International Space Station (ISS) and also to the Moon. Improvements in the life and robustness of the Portable Life Support System (PLSS) has been a major objective of these efforts. The Suit Water Membrane Evaporator (SWME) was chosen as the technology to provide cooling to the xEMU and has undergone several iterations of development over this period. An ISS flight experiment centered around the SWME and other thermal loop technologies was developed and has been under test in an ISS EXpedite PRocessing of Experiments to the Space Station (EXPRESS) rack since November of 2020. In addition to the SWME, The SWME EXPRESS Rack Flight Experiment (SERFE) contains several technology demonstrations from the xEMU project and has been demonstrating their performance in micro-gravity and over an extended duration. This paper summarizes the design and operation of the SERFE experiment and provides a basis for subsequent papers to focus on more specific aspects of performance of individual technologies.