Browsing by Author "Cox, Marlon"
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Item NextSTEP Appendix A Modular ECLSS Effort Lessons Learned(2023 International Conference on Environmental Systems, 2023-07-16) Clawson, James; Barta, Daniel; Schneider, Walter; Howard, David; Cox, MarlonThe first appendix under NextSTEP-2, Appendix A, focused on developing deep space habitation concepts, engineering design and development, and risk reduction efforts leading to a habitation capability in cislunar space. Collins Aerospace, formerly UTC Aerospace Systems (UTAS), was awarded a Phase 1 and subsequent Phase 2 contract to �develop concepts that group ECLS systems into logical modules maximizing the use of common components and the development of unique methods and design concepts that support in-flight maintenance and repair for future exploration systems.� This effort developed and matured a modular palletization concept to enable standard rack interfaces, post-launch outfitting, and decoupling of structural supports that withstand launch environments from those needed for lower on-orbit loads, Collins also assessed numerous architecture trades, including the use of condensing and noncondensing heat exchangers, the ability of modular units to accommodate various habitat volumes and thermal loading, and the most appropriate order and timing of delivery of regenerative ECLSS hardware to orbital habitats. Collins additionally developed software approaches for distributed/modular command, control, and communication systems and innovative Bayesian fault detection and isolation techniques. Finally, the effort explored advanced maintainability and supportability concepts including the definition of maintenance units (MUs) in place of the traditional Orbital Replacement Units (ORUs), increasing parts commonality to reduce the number and type of spare parts, the use of augmented reality to guide crews during maintenance and repair procedures, and how crews would prepare for and recover from long durations of habitat dormancy. Now that the NextSTEP Modular ECLSS effort has come to a close, it's important to summarize the work accomplished under this effort and identify the lessons learned and where they can be leveraged to improve NASA's broader program of ECLSS technology development and demonstration and ultimately how they can increase the performance of future surface and orbital habitats.Item Oxygen Compatibility and Challenge Testing of the Portable Life Support System Variable Oxygen Regulator for the Advanced Extravehicular Mobility Unit(47th International Conference on Environmental Systems, 2017-07-16) Campbell, Colin; Cox, Marlon; Falconi, Eric; Meginnis, Carly; Barnes, Bruce; Conger, BruceThe Variable Oxygen Regulator (VOR), a stepper-actuated two-stage mechanical regulator, is being developed for the purpose of serving as the Primary Oxygen Regulator (POR) and Secondary Oxygen Regulator (SOR) within the Advanced Extravehicular Mobility Unit (EMU) Portable Life Support System (PLSS), now referred to as the xEMU and xPLSS. Three prototype designs have been fabricated and tested as part of this development. Building upon the lessons learned from the 35 years of Space Shuttle/International Space Station EMU Program operation, including the fleet-wide EMU Secondary Oxygen Pack (SOP) contamination failure that occurred in 2000, NASA is analyzing, designing, and testing the VOR for oxygen compatibility with controlled Non-Volatile Residue (NVR) and a representative worst-case hydro-carbon system contamination event (>100 mg/ft2 dodecane). This paper discusses the steps taken in testing of VOR 2.0 for oxygen compatibility, and discusses follow-on design changes implemented in the VOR 3.0 (3rd prototype) as a result.Item Space Suit Portable Life Support System (PLSS) 2.0 Pre-Installation Acceptance (PIA) Testing(46th International Conference on Environmental Systems, 2016-07-10) Anchondo, Ian; Cox, Marlon; Watts, Carly; Westheimer, David; Vogel, MatthewFollowing successful completion of the space suit Portable Life Support System (PLSS) 1.0 development and testing in 2011, the second system-level prototype, PLSS 2.0, was developed in 2012 to continue the maturation of the advanced PLSS design. This advanced PLSS is intended to reduce consumables, improve reliability and robustness, and incorporate additional sensing and functional capabilities over the current Space Shuttle/International Space Station Extravehicular Mobility Unit (EMU) PLSS. PLSS 2.0 represents the first attempt at a packaged design comprising first generation or later component prototypes and medium-fidelity interfaces within a flight-like representative volume. Pre-Installation Acceptance (PIA) is carryover terminology from the Space Shuttle Program referring to the series of test sequences used to verify functionality of the EMU PLSS prior to installation into the Space Shuttle airlock for launch. As applied to the PLSS 2.0 development and testing effort, PIA testing designated the series of 27 independent test sequences devised to verify component and subsystem functionality, perform in situ instrument calibrations, generate mapping data, define set-points, evaluate control algorithms, evaluate hardware performance against advanced PLSS design requirements, and provide quantitative and qualitative feedback on evolving design requirements and performance specifications. PLSS 2.0 PIA testing was carried out in 2013 and 2014 using a variety of test configurations to perform test sequences that ranged from stand-alone component testing to system-level testing, with evaluations becoming increasingly integrated as the test series progressed. Each of the 27 test sequences was vetted independently, with verification of basic functionality required before completion. Because PLSS 2.0 design requirements were evolving concurrently with PLSS 2.0 PIA testing, the requirements were used as guidelines to assess performance during the tests; after the completion of PIA testing, test data served to improve the fidelity and maturity of design requirements as well as plans for future advanced PLSS functional testing.Item Space Suit Portable Life Support System 2.0 Unmanned Vacuum Environment Testing(47th International Conference on Environmental Systems, 2017-07-16) Anchondo, Ian; Cox, Marlon; Meginnis, Carly; Westheimer, David; Vogel, MatthewFor the first time in more than 30 years, an advanced space suit Portable Life Support System (PLSS) design was operated inside a vacuum chamber representative of the flight operating environment. The test article, PLSS 2.0, was the second system-level integrated prototype of the advanced PLSS design, featuring first generation or later prototypes for all components less instrumentation, tubing and fittings. Developed throughout 2012, PLSS 2.0 was the first attempt to package the system into a flight-like representative volume. PLSS 2.0 testing included an extensive functional evaluation called Pre-Installation Acceptance (PIA) testing, Human-in-the-Loop testing in which the PLSS 2.0 prototype was integrated via umbilicals to a manned space suit for 19 two-hour simulated EVAs, and unmanned vacuum environment testing. The latter test sequence took place from 1/9/15-7/9/15 with PLSS 2.0 located inside a vacuum chamber. Test sequences included performance mapping of several components, carbon dioxide removal evaluations at simulated intravehicular activity (IVA) conditions, a regulator pressure schedule assessment, and culminated with 25 simulated extravehicular activities (EVAs). During the unmanned vacuum environment test series, PLSS 2.0 accumulated 378 hours of integrated testing including 291 hours of operation in a vacuum environment and 199 hours of simulated EVA time. In addition to generating an extensive database of PLSS 2.0 performance data, achievements included requirements and operational concepts verification, as well as demonstration of vehicular interfaces, consumables sizing and recharge, and water quality control.