Browsing by Author "Mcfarland, Shane"
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Item Development Of An Objective Space Suit Mobility Performance Metric Using Metabolic Cost And Functional Tasks(46th International Conference on Environmental Systems, 2016-07-10) Mcfarland, Shane; Norcross, JasonExisting methods for evaluating EVA suit performance and mobility have historically concentrated on isolated joint range of motion and torque. However, these techniques do little to evaluate how well a suited crewmember can actually perform during an EVA. An alternative method of characterizing suited mobility through measurement of metabolic cost to the wearer has been evaluated at Johnson Space Center over the past several years. The most recent study involved six test subjects completing multiple trials of various functional tasks in each of three different space suits; the results indicated it was often possible to discern between different suit designs on the basis of metabolic cost alone. However, other variables may have an effect on real-world suited performance; namely, completion time of the task, the gravity field in which the task is completed, etc. While previous results have analyzed completion time, metabolic cost, and metabolic cost normalized to system mass individually, it is desirable to develop a single metric comprising these (and potentially other) performance metrics. This paper outlines the background upon which this single-score metric is determined to be feasible, and initial efforts to develop such a metric. Forward work includes variable coefficient determination and verification of the metric through repeated testing.Item Mechanical Counter-Pressure EVA Suits: NASA Outlook and Development Strategy in 2022(51st International Conference on Environmental Systems, 7/10/2022) Mcfarland, ShaneMechanical counter-pressure has been investigated as a possible alternative architecture to traditional extra-vehicular activity suits for some time. MCP aims to provide physiological protection against the ambient vacuum environment by direct application of pressure to the skin by a fabric, as opposed to surrounding the occupant in pressurized gas as is the defining characteristic of a traditional gas-pressurized suit. In reviewing the concept of MCP, it offers distinct hypothetical advantages to traditional EVA suits: reduced mass, consumables, and complexity; increased mobility and comfort. In addition, as rudimentary feasibility of the concept was established in the 1960s with the testing of the Space Activity Suit, MCP seems poised to inevitably supplant traditional EVA architectures with a modest degree of concentrated development. However, a closer examination suggests something quite different. This paper serves as a comprehensive summary of the technical work that has been completed related to MCP from 1960 to 2022, the technical gaps that currently prohibit development of a flight-capable design, and outlines a development strategy that serves to address these gaps moving forward over the coming decades.Item NASA Advanced Space Suit Pressure Garment System Status and Development Priorities 2019(49th International Conference on Environmental Systems, 2019-07-07) Ross, Amy; Rhodes, Richard; Mcfarland, ShaneThis paper discusses the current focus of NASA’s Advanced Space Suit Pressure Garment Technology Development team’s efforts, the status of that work, and a summary of longer term technology development priorities and activities. The Exploration Extra-vehicular Activity Unit (xEMU) project’s International Space Station Demonstration Suit (xEMU Demo) project continues to be the team’s primary customer and effort. In 2018 the team was engaged in addressing hardware design changes identified in the Z-2 pressure garment prototype Neutral Buoyancy Laboratory (NBL) test results. These changes will be discussed. Additionally components whose first iterations were produced in 2018 will be discussed. A full pressure garment prototype, termed Z-2.5, was assembled that is composed of updated and first prototype iteration hardware. Z-2.5 NBL testing, performed from October 2018 through April 2019 will inform final design iterations in preparation for the xEMU Demo preliminary design review planned to occur in the third quarter of government fiscal year 2019. A primary objective of the Z-2.5 NBL testing is to validate changes made to the hard upper torso geometry, which depart from the planetary walking suit upper torso geometry that has been used over the last 30 years. The team continues to work technology development, with GFY2018 work being used to supplement and feed the gaps left by the scope defined for the xEMU Demo. Specifically, a Phase IIx Small Business Innovative Research Grant to mature durable bearings that are compatible with a dust environment and a grant funded by the Science Technology Mission Directorate, Lightweight and Robust Space Suit (LARSS) project, to mature planetary impact requirements and hardware will be described. Finally, a brief review of longer-term pressure garment challenges and technology gaps will be presented to provide an understanding of the advanced pressure garment team’s technology investment priorities and needs.Item NASA Advanced Space Suit Pressure Garment System Status and Development Priorities 2022(51st International Conference on Environmental Systems, 7/10/2022) Mcfarland, Shane; Rhodes, Richard; Campbell, DonThis paper discusses the current focus of NASA's Advanced Space Suit Pressure Garment Technology Development team's efforts, the status of that work, and a summary of longer-term technology development priorities and activities. For the past two years, the team has focused on the development and detailed design of the Extra-vehicular Mobility Unit (xEMU) to support two parallel missions: A 2023 deadline for delivery of the xEMU International Space Station (ISS) Demonstration configuration, and a planetary walking suit configuration to support landing on the Moon in 2024. The baselined design of the xEMU will be reviewed. The results of Design Verification Testing (DVT) will be presented and its ability to provide confidence in the hardware's ability to meet flight requirements will be discussed. To the extent possible, an impact assessment of the Exploration Extravehicular Activity Services (xEVAS) Contract will be provided. Finally, a brief review of longer-term pressure garment challenges and technology gaps will be presented to provide an understanding of the advanced pressure garment team's technology investment priorities and needs for future exploration missions.Item NASA Advanced Space Suit Pressure Garment System Status and Development Priorities 2023(2023 International Conference on Environmental Systems, 2023-07-16) Mcfarland, Shane; Campbell, Don; Rhodes, RichardThis paper discusses the current focus of NASA’s Advanced Space Suit Pressure Garment Technology Development team’s efforts, the status of that work, and a summary of longer term technology development priorities and activities. The Exploration Extra-vehicular Activity Mobility Unit (xEMU) has been the team’s primary effort over the past several years. ICES papers in 2022 detailed the design of the xEMU pressure garment components. This paper outlines the design updates to the xPGS since that time. More notably, this paper documents the various tests executed with the xPGS to evaluate its performance, durability, and acceptability for microgravity and Lunar missions. An overview of ongoing and planned xEMU testing and training is provided. The PGS team’s transition from xEMU development and testing, to supporting the Exploration Extravehicular Activity Services (xEVAS) vendors is discussed. In addition, technology development efforts in coordination with the EVA and Human Surface Mobility Program (EHP), the NASA Engineering Safety Council (NESC) and the Small Business Innovation Research (SBIR) Program will be discussed in the context of supporting sustaining EVA operations on the Lunar surface over the coming decade. Finally, a brief review of longer-term pressure garment challenges and technology gaps will be presented to provide an understanding of the advanced pressure garment team’s technology investment priorities and needs.Item NASA Advanced Space Suit xEMU Development Report -- Liquid Cooling and Ventilation Garment(51st International Conference on Environmental Systems, 7/10/2022) Mcfarland, Shane; Cox, DavidFor the past several years, the Exploration Extra-Vehicular Mobility Unit (xEMU) team at NASA's Johnson Space Center has focused on the development and detailed design of the xEMU to support missions to the International Space Station (ISS) and a moon landing in 2024. In that context, this paper examines the development and baseline detailed design of the xEMU liquid cooling and ventilation garment (LCVG). This paper will outline the challenging technical requirements, significant architectural trades, technical solutions required to overcome these challenges, and a current status of the detailed design. The preliminary results of Design Verification Testing (DVT) as it relates specifically to this hardware will also be provided, along with a forward strategy for final maturation into a flight-ready design.Item NASA Advanced Space Suit xEMU Development Report -- Lunar Boots(51st International Conference on Environmental Systems, 7/10/2022) Mcfarland, Shane; Fester, ZacharyFor the past several years, the Exploration Extra-Vehicular Mobility Unit (xEMU) team at NASA's Johnson Space Center has focused on the development and detailed design of the xEMU to support missions to the International Space Station (ISS) and a moon landing in 2024. In that context, this paper examines the development and baseline detailed design of the Lunar Boots. This paper will outline the challenging technical requirements, significant architectural trades, technical solutions required to overcome these challenges, and a current status of the detailed design. The preliminary results of Design Verification Testing (DVT) as it relates specifically to this hardware will also be provided, along with a forward strategy for final maturation into a flight-ready design.Item The “Space Activity Suit” – A Historical Perspective and A Primer On The Physiology of Mechanical Counter-Pressure(49th International Conference on Environmental Systems, 2019-07-07) Mcfarland, Shane; Ross, Amy; Sanders, RobertSince the 1950s, mechanical counter-pressure [MCP] has been investigated as a possible alternative design concept to traditional extra-vehicular activity [EVA] space suits. While traditional gas-pressurized EVA suits provide physiological protection against the ambient vacuum by means of pressurized oxygen to at least 3.1 psia (160 mmHg), MCP provides protection by direct application of pressure on the skin by a fabric. In reviewing the concept, MCP offers distinct potential advantages to traditional EVA suits: lower mass, reduced consumables, increased mobility, increased comfort, less complexity, and improved failure modes. In the mid 1960s to early 1970s, Dr. Paul Webb of Webb Associates developed and tested such a suit under funding from NASA Langley Research Center. This “Space Activity Suit” [SAS] was improved many times while testing in the laboratory and an altitude chamber to as low as 0.3 psia (15 mmHg). This testing, and the reports by Webb documenting it, are often presented as evidence of the feasibility of MCP. In addition, the SAS reports contain a wealth of information regarding the physiological requirements to make MCP work at the time, which is still accurate today. This paper serves to document the Space Activity Suit effort and analyze it in today’s context.Item Z-2 Space Suit: A Case Study in Human Spaceflight Public Outreach(46th International Conference on Environmental Systems, 2016-07-10) Mcfarland, ShaneNASA Johnson Space Center’s Z-series of planetary space suit prototypes is an iterative development platform with a Mars-forward design philosophy, targeting a Mars surface mission in the mid-2030s. The first space suit assembly, called the Z-1, was delivered in 2012. While meeting the project’s stated requirements and objectives, the general public’s reception primarily focused on the color scheme, which vaguely invoked similarity to a certain animated cartoon character. The public at large has and continues to be exposed to varying space suit design aesthetics from popular culture and low TRL technology maturation efforts such as mechanical counterpressure. The lesson learned was that while the design aesthetic is not important from an engineering perspective, the perception of the public is important for NASA and human spaceflight in general. For the Z-2 space suit, an integrated public outreach strategy was employed to engage, excite and educate the public on the current technology of space suits and NASA’s plans moving forward. The keystone of this strategy was a public vote on three different suit cover layer aesthetics, the winner of which would be used as inspiration in fabrication. Other components included social media, university collaboration, and select media appearances, the cumulative result of which, while intangible in its benefit, was ultimately a positive effect in terms of the image of NASA as well as the dissemination of information vital to dispelling public misconceptions.