Browsing by Author "Bekdash, Omar"
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Item Characterization of the Nasal Cannula as a Carbon Dioxide Washout Measurement Technique in the Mark III Space Suit(46th International Conference on Environmental Systems, 2016-07-10) Meginnis, Ian; Norcross, Jason; Bekdash, Omar; Ploutz-Snyder, RobertA space suit must provide adequate carbon dioxide (CO2) washout inside the helmet to prevent symptoms of hypercapnia. In the past, an oronasal mask has been used to measure the inspired air of suited subjects to determine a space suit’s CO2 washout capability during ground-based tests. Although sufficient for super-ambient pressure testing of space suits, the oronasal mask fails to meet several human factors and operational criterion needed for future sub-ambient pressure testing (e.g., compatibility with a Valsalva device). This paper describes the evaluation of a nasal cannula as a device for measuring inspired air within a space suit. Eight test subjects were tasked with walking on a treadmill or operating an arm ergometer to achieve target metabolic rates of 1000, 2000, and 3000 British thermal units per hour (BTU/hr) at helmet ventilation flow rates of 2, 4, and 6 actual cubic feet per minute (ACFM). The test points at lower metabolic rates were conducted twice, with subjects instructed to breathe either through the nose only or however they felt comfortable. Comparing nasal cannula test data to historical oronasal mask data shows that the nasal cannula provides more statistically consistent data across test subjects than the oronasal mask, regardless of the breathing style. The data also shows that inhaling/exhaling through only the nose provides a lower sample variance than an unrestricted breathing style. However, it may not be realistic to require nose-only breathing for future CO2 washout evaluations because test subjects cannot breathe through their nose continuously at high metabolic rates. The test subjects in this study also provided feedback to human factors criteria, reporting that the nasal cannula is comfortable and can be used with a Valsalva device.Item Development and Evaluation of the Active Response Gravity Offload System as a Lunar and Martian EVA Simulation Environment(2020 International Conference on Environmental Systems, 2020-07-31) Bekdash, Omar; Valle, Paul; Kim, Kyoung Jae; Jarvis, Sarah; Dunn, Jocelyn; Norcross, Jason; Abercromby, AndrewIn preparation for future exploration missions, NASA seeks the ability to simulate partial-gravity operations for use in ground-based research, crew training, and engineering design evaluations. The Active Response Gravity Offload System (ARGOS) at the Johnson Space Center (JSC) is designed to simulate reduced-gravity environments, such as lunar, Martian, or microgravity, using a robotic system similar to an overhead bridge crane. The ARGOS continuously offloads a portion of a suited human’s weight during all dynamic motions within the test facility, which can include basic functional movements such as walking, running, and jumping, as well as a wide range of planetary surface activities. This system will be used as part of a metabolic-rate task characterization study to determine the workload associated with partial-gravity extravehicular activity (EVA). Pilot testing was conducted using the MKIII prototype planetary space suit and 2 gimbal designs to determine the ability of the ARGOS test environment to simulate planetary EVA operations. This paper will describe the lessons learned from the feasibility testing, simulation-environment mockup design, and the results from the pilot tests and their influence into the final study design. Being able to effectively simulate partial-gravity environments and characterize the performance of crewmembers will have an impact on multiple domains including suit design, task design, thermal models, and life-support-system capacity verification plans, among others.Item Monitoring Human Performance during Suited Operations: A Technology Feasibility Study Using Extravehicular Mobility Unit Gloves(45th International Conference on Environmental Systems, 2015-07-12) Bekdash, Omar; Norcross, Jason; McFarland, ShaneMobility tracking of human subjects while conducting suited operations still remains focused on the external movement of the suit and little is known about the human movement within. For this study, accelerometers and bend-sensitive resistors were integrated into a custom-carrier glove to quantify range-of-motion and dexterity from within the pressurized- glove environment as a first-stage feasibility study of sensor hardware, integration, and reporting capabilities. Sensors were also placed on the exterior of the pressurized glove to determine whether it was possible to compare a glove-joint angle to the anatomical-joint angle of the subject during tasks. Quantifying human movement within the suit was feasible, with accelerometers clearly detecting movements in the wrist and reporting expected joint angles at maximum flexion or extension postures with repeatability of ±5o between trials. Bend sensors placed on the proximal interphalangeal and distal interphalangeal joints performed less well than the accelerometers and did not reflect joint positions accurately. It was not possible to determine the actual joint angle using these bend sensors, but these sensors could be used to determine when the joint was flexed to its maximum and provide a general range of mobility needed to complete a task. Now that we understand the requirements and limitations of embedding hardware in the suit environment, further work includes additional testing with accelerometers and the possible inclusion of hardware such as magnetometers or gyroscopes to more precisely locate the joint in three-dimensional space. We hope to eventually expand beyond the hand and glove and develop a more comprehensive suit sensor suite to characterize motion across more joints (e.g., knee, elbow, shoulder, etc.) and fully monitor the human body operating within the suit environment.Item Physical and Cognitive Exploration Simulations: Development of Exploration Tasks and Analog Environment Testing Capabilities(50th International Conference on Environmental Systems, 7/12/2021) Bekdash, Omar; Welsh, Lawrence; Scheib, Bridget; Dunn, Jocelyn; Kim, Kyoung Jae; Abercromby, AndrewIn preparation for future exploration missions, NASA seeks the ability to acceptably simulate partial gravity operations for use in ground-based research, crew training, and engineering design evaluations. Performing extravehicular activity (EVA) in the partial gravity environments of the moon and Mars will require higher workloads and greater crew autonomy than current International Space Station (ISS) EVAs. Understanding how this increased demand on the crewmember impacts performance or drives changes to EVA system design or operations is necessary for mission success. The Physical and Cognitive Exploration Simulations (PACES) project at the Johnson Space Center (JSC), is a platform for development of EVA simulation capabilities and performance measurement methods to perform those evaluations. PACES aims to define flight-like exploration tasks which simulate the physical and cognitive workload associated with exploration EVA operations. Each task contains specific objectives, performance metrics, and outcomes of performing the actions; these metrics can be used to evaluate a wide range of mission parameters and capabilities, such as timelines, EVA informatics technologies, task procedures, and EVA hardware designs, among others. These modules are then implemented across a wide variety of analog and training environments (e.g., partial gravity simulators, hybrid reality, field work) to consistently evaluate and compare crew performance from a common catalog of activities. By maintaining commonality of task implementation and measurement methods, PACES helps to enable development of tools such as timeline trackers, human health and performance predictive models, and EVA decision support systems which can be deployed consistently in any analog environment. This paper will describe the PACES development methodology and standard measures, tasks that have been developed to simulate lunar EVAs, and summary results from analog environment testing at the Neutral Buoyancy Laboratory (NBL) and Active Response Gravity Offload System (ARGOS) facility.Item Validation of Inspired Carbon Dioxide Measurement Methods in the Extravehicular Mobility Unit Space Suit(48th International Conference on Environmental Systems, 2018-07-08) Bekdash, Omar; Norcross, Jason; Fricker, John; Meginnis, Ian; Abercromby, Andrew; Young, MillenniaNASA seeks a validated, standardized methodology for measuring the inspired carbon dioxide gas (CO2) in Extravehicular Activity (EVA) and Launch, Entry, Abort (LEA) pressure suits to verify that ventilation designs maintain safe levels of CO2 during all suited operations. To date, various methods have been used to assess the CO2 washout capability of different spacesuits using a variety of in-suit sampling techniques and devices, however, none have enabled adoption of a standard method applicable to all space suit testing. Previous work conducted at the NASA Johnson Space Center characterized inspired CO2 measurement equipment and methods to develop a standard method for verification of suit CO2 washout performance. This method minimizes and quantifies test equipment induced measurement error, and defines the analysis methods for calculation of the in-suit inspired CO2 and washout performance. In this follow-on study, human-in-the-loop (HITL) testing was completed using the Extravehicular Mobility Unit (EMU) to validate this new methodology and gather data for characterization of the washout performance of the longest continually operating EVA space suit design. This included sample probe efficacy assessment, analysis of the potential importance of subject selection during HITL CO2 washout testing by gathering physiological data characterizing intra-subject and inter-subject variability, and collection of in-suit transcutaneous CO2 measurements for added contextual evidence of washout performance. Data collected in this methodology validation will be used to characterize the EMU which will ultimately inform the development of standard test practices and provide data for evidence-based in-suit CO2 exposure requirements.