Browsing by Author "Davis, Kristine"
Now showing 1 - 12 of 12
- Results Per Page
- Sort Options
Item Electrochromic Visors for Advanced Spacesuit Helmets(51st International Conference on Environmental Systems, 7/10/2022) Argun, Avni; Weber, Andrew; Markham, David; Davis, Kristine; Kukla, TymonNASA's Extravehicular Mobility Unit (EMU) is a personal spacecraft that comprises the spacesuit assembly and life support systems. The current EMU has a manually operated extravehicular visor assembly (EVVA) that uses a reflective gold visor to reduce the intensity of incoming solar radiation. This binary method requires crew members to manually raise or lower the visor depending on ambient light conditions. There is a need for developing an advanced visor system with tunable tinting to provide improved visibility with hands free operation. Integration of a dynamically switching technology with NASA�s next generation spacesuit helmet would provide continuous shading, radiation protection, and optimized light modulation. Taking advantage of solution processed electrochromic polymers (ECP), Giner is developing a functionally improved alternative to the existing EVVA. Giner�s automated polymer processing on doubly-curved surfaces and electrochromic device fabrication methods are readily adapted to a wide variety of substrates with unique geometries. By combining color-neutral ECPs with transparent electrode coatings, Giner has successfully demonstrated tunable optical switching on curved polycarbonate substrates and obtained high optical contrast (>55% ?T at 550 nm) with rapid response times (<3 sec). The devices show excellent switching stability (<5% ?T loss over 1,000 switches), long optical memory (<1% ?T loss after removal of power at open circuit), and low energy consumption (0.150 watt-Hours per 1,000 cycles for 6� x 10� active area). Fully developed, Giner�s dynamic visor will be compatible for integration with NASA�s new generation spacesuit helmet to allow instant darkening when exposed to sunlight to protect the astronaut�s eyes from solar glare. In addition, the versatile and scalable device platform could provide variable shading on windows used in space stations and vehicles, or on deep space shelters.Item Exploration Extravehicular Mobility Unit (xEMU) Helmet and Extravehicular Visor Assembly (EVVA) Chamber B Thermal Vacuum Testing Results(2024 International Conference on Environmnetal Systems, 2024-07-21) Swartout, Ben; Davis, Kristine; Westheimer, DavidNASA�s Exploration Extravehicular Mobility Unit (xEMU) is the government reference next-generation space suit design and is engineered to protect astronauts from extreme lunar environmental temperatures. To evaluate the xEMU hardware thermal requirements, the xEMU Testing Team invented, designed, and executed a dual-suit, uncrewed thermal vacuum (TVAC) test at Johnson Space Center�s (JSC) Chamber B. This paper details the test methodology, hardware setup, and results from the xEMU helmet and extravehicular visor assembly (EVVA). Two helmets/EVVAs were tested simultaneously in Chamber B, with different thermal environments and EVVA configurations. For the helmet/EVVA on the Short xEMU (SxEMU) test article, five thermal profiles were tested during five simulated EVAs, with varying visor and shade configurations. For the helmet/EVVA on the second xEMU, eleven unique thermal profiles were tested including both cold and hot environmental cases over the course of five continuous days of testing, with a single visor and shade configuration. The radiative thermal environment was controlled though exposure to liquid-nitrogen shrouds on the chamber walls and though a two separate heater cages surrounding each respective test article. The thermal effects of the Exploration Informatics (xINFO) lights and camera on the helmet/EVVA was also tested. Twenty-two temperature sensors were used to collect data in critical locations in the xEMU helmet/EVVA assembly. This paper will document the testing results and compare the test data against the xEMU helmet/EVVA and system-level thermal models for model validation. To conclude, this paper will address knowledge gaps presented by unmanned thermal vacuum testing with regard to the helmet and the current state of lunar helmet/EVVA thermal testing.Item Exploration Helmet Permanent Anti-fog Study(2023 International Conference on Environmental Systems, 2023-07-16) Davis, Kristine; Trude, GregFor the current Extravehicular Mobility Unit (EMU) spacesuit, an astronaut applies an anti-fog solution to the interior of the helmet bubble before each EVA. However, the anti-fog solution has been reported to cause eye discomfort during at least seven EMU EVAs when the anti-fog solution contacted the crew member’s eyes. During STS-100, astronaut Chris Hadfield reported the eye irritation temporarily blinded him during his spacewalk. In addition, the wipe on anti-fog solution is a consumable that needs to be accounted for and a supply launched for missions. To solve this, the Exploration EMU (xEMU) pressure bubble investigated using a permanent anti-fog coating during Design Verification and Test (DVT) human in the loop (HITL) events. Chosen for previous use in Constellation Space Suit develop, HTAF-601, a water based permanent anti-fog solution, was tested. However, major issues have arisen with further HITL testing with the coating. Cleaning the helmet has been a challenge to avoid damaging the permanent anti-fog coating. NASA has completed a set of different methods for cleaning the anti-fog to try to document a preferred method. Even with using a very gentle cleaning method of flushing with distilled or DI water and dabbing at facial oils, the permanent anti-fog starts to delaminate consistently after 50 hours manned pressurized time (MPT). Finally, the HTAF-601 coating is being discontinued by the vendor. Due to these issues, further investigation is being completed evaluating two solvent based anti-fog solutions: Exxene’s HCF-100 and FSI’s Visgard 106-94. Each coating will be evaluated on polycarbonate samples for application consistency, steam cycles (mimicking breath cycles), cleaning durability, haze, and light transmission. This study will determine if either coating is a viable option to pursue as a permanent anti-fog for spacesuit helmet applications.Item Initial Testing of the Exploration Extravehicular Mobility Unit (xEMU) in Lunar Environment Simulation at the Neutral Buoyancy Lab (NBL) in 2022(2023 International Conference on Environmental Systems, 2023-07-16) Davis, Kristine; Tejral, Zachary; Keomany, Tommy; Vu, LinhUnderstanding how to effectively train for Extravehicular Activities (EVAs) for Artemis missions is critical. Tasked by the new Extravehicular Activity and Human Surface Mobility Program (EHP), a team of stakeholders from engineering and flight operations worked together to test the Exploration Extravehicular Mobility (xEMU) in the Neutral Buoyancy Lab (NBL) simulating the lunar environment. The NBL is a pool in which astronauts are typically trained to complete simulated International Space Station (ISS) EVA tasks in a neutral weigh-out. The overall focus for this test series was evaluating how well the NBL could be used as an effective simulated environment for Artemis lunar EVAs. New NBL support hardware was manufactured to support this test series and update the interfaces to be more representative of xEMU hardware such as a new NBL Portable Life Support System (PLSS) mock-up and umbilical, lights and cameras, and display and control unit (DCU). To simulate the 1/6th-gravity (1/6-g) environment, extra weights were added around the suit to create an accurate center of gravity representation. The Partial Gravity Weigh-out Stand (PGWS) predicted where and how much weight would be required for the 1/6th-G simulation and predicted the center of gravity placement. After the weigh-out attempt was completed, the suited participant would complete a set of directed tasks such as kneeling, object pick-up, and walking to evaluate the weigh-out. To create the lunar environment, sand, boulders, and ramps were added to the pool floor. Overall, the NBL was able to create an acceptable lunar landscape and ability to have two subjects work side by side in pressurized xEMUs which currently cannot be achieved in other test environments. Achieving a stable 1/6th-G lunar weigh-out and clear, consistent dual suit communications was a challenge for this series. Future work is planned to continue to improve this simulation environment.Item Integrative Fit Assessments for Multi-Component Stack-Up of xEMU(50th International Conference on Environmental Systems, 7/12/2021) Davis, Kristine; Rhodes, Richard; Rajulu, Sudhakar; Hernandez, Yaritza; Benson, Elizabeth; Jarvis, Sarah; Gupta, Garima; Kim, HanSufficient mobility, proper fit, and adequate comfort are critical design goals for the Exploration Extravehicular Mobility Unit (xEMU), NASA's next generation spacesuit. While component-wise fit assessments can provide baseline information, the wearers' experience might be different when multiple components are stacked and integrated together. This study is concerned with the fit, comfort, and mobility associated with the stack-up of the Hard Upper Torso (HUT), Lower Torso Assembly (LTA) and other interconnecting components. The first aim of this study was to identify the sizing ring configuration preferred by wearers of different body shapes and sizes. Sizing rings are inserts placed between the Body Seal Closure of the HUT and the waist bearing. Sizing rings of different heights can be combined to accommodate the wearer's torso size. Human test subjects wore the stack-up of 3D printed mockups and performed prescribed functional EVA postures as they were surveyed for feedback on fit and comfort. The second aim was to assess the effect of elongating the brief height by 50.8 mm, instead of using a same height sizing ring. The hypothetical benefit was a closer alignment of the mechanical pivot point of the brief with the anatomical low back joint center, especially for wearers with a longer torso. Human-in-the-loop testing was performed to compare the baseline and elongated brief configurations, with a focus on mobility and comfort differences. Based on the test outcome, a statistical model is currently in development to predict the optimal sizing ring and brief configuration as a function of the wearer's anthropometry. This study can also help to determine the largest and smallest body sizes in crew populations that can be accommodated with the HUT-to-LTA stack-up, with increased mobility and comfort.Item LTV-xEVA Applied Injury Biomechanics(2024 International Conference on Environmnetal Systems, 2024-07-21) Yates, Keegan; Drake, Aaron; Davis, KristineBeginning in Artemis V, Lunar Terrain Vehicles (LTV) will be utilized to enable astronauts to explore the lunar south pole and conduct science farther from the landing site than during the Apollo program. However, LTV operation has the potential to cause injury to the suited crew member during their Extravehicular Activity (EVA). Injury risk caused by LTV acceleration and jerk combined with blunt loading from rigid suit components needs to be better understood. An effort began to create requirements, model, and address the injury risk caused by the LTV combined with Exploration EVA (xEVA) suits. Mitigation of crew injury is a shared responsibility between LTV and the suit since neither can accomplish this independently. The modeling completed in Fiscal Year 2023 (FY23) helped to verify the fidelity of the requirements and parse out vendor responsibility (LTV, xEVAS, or NASA) for Artemis V+. The scope of the modeling in FY23 used the LTV System Requirements Document (SRD) as worst-case inputs and modeled female 5th, male 50th, and male 95th percentile subjects in hard-mounted seated and semi-standing postures. Soft-mounted (i.e. lap belt) and testing to validate the analysis was determined out of scope for FY23 work.Item NASA Advanced Space Suit xEMU Development Report -- Helmet and Extra-Vehicular Visor Assembly (EVVA)(51st International Conference on Environmental Systems, 7/10/2022) Davis, Kristine; Kukla, TymonFor 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 Helmet and Extra-Vehicular Visor Assembly (EVVA). 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 -- Waist Brief Hip(51st International Conference on Environmental Systems, 7/10/2022) Davis, Kristine; Grimes, Jaren; Stephens, ChanelFor 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 Waist Brief Hip (WBH). 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 Performance of the Z-2 Space Suit in a Simulated Microgravity Environment(48th International Conference on Environmental Systems, 2018-07-08) Meginnis, Ian; Davis, Kristine; Rhodes, RichardThe Z-2 space suit is the product of the last fifty years of NASA’s space suit research and testing experience. The suit was originally built as a prototype exploration space suit to evaluate advances in suit design and technology for use on a planetary surface. After the delivery of Z-2, however, NASA shifted focus and sought to evaluate the feasibility of using design features of the Z-2 suit to inform the design of the xEMU Demo space suit, which will be demonstrated on the International Space Station (ISS). Aside from being developed primarily to evaluate the overall architecture of the xEMU space suit, the xEMU Demo may also supplement or replace the existing Extravehicular Mobility Unit (EMU). To evaluate the microgravity performance of the Z-2 architecture for compatibility on the ISS, the suit was tested in NASA’s Neutral Buoyancy Laboratory (NBL), which is the primary microgravity testing environment for space suits. The Z-2 NBL test series began in the fall of 2016 and concluded in the fall of 2017. Five astronauts performed various tasks that are representative of the tasks performed on the ISS. Test subjects performed tasks in the Z-2 suit and the EMU so that relative comparisons could be drawn between the two suits. Two configurations of the Z-2 space suit were evaluated during this test series: the ELTA configuration and the ZLTA configuration. The ELTA configuration, which was the primary test configuration, is comprised of the Z-2 upper torso and the EMU lower torso. The ZLTA configuration is comprised of the Z-2 upper torso with the Z-2 lower torso, which contains additional mobility elements. This paper discusses the test results from the Z-2 NBL test series.Item Testing of the NASA Exploration Extravehicular Mobility Unit Demonstration (xEMU Demo) Architecture at the Neutral Buoyancy Laboratory(49th International Conference on Environmental Systems, 2019-07-07) Davis, Kristine; Meginnis, IanFollowing Z-2 space suit testing that occurred from 2016-2017, the Exploration Extravehicular Mobility Unit (xEMU) Project was tasked with building a demonstration unit of the xEMU space suit to test on the International Space Station (ISS) in 2023. This suit is called xEMU Demonstration Suit (xEMU Demo). Based on feedback from astronauts during the Z-2 NBL test series, design changes were made, resulting in a new prototype suit called the Z-2.5 space suit. The design of the Z-2.5 space suit with an exploration Portable Life Support Systems (xPLSS) mock-up represents the architecture of xEMU Demo. The team is testing Z-2.5 in the NBL to evaluate this architecture and validate changes made from Z-2. The results will inform the xEMU Demo design going forward to its Preliminary Design Review (PDR) in the summer of 2019. This Z-2.5 NBL test series focuses on evaluating the microgravity performance of the suit and the ability to complete ISS-related tasks. The series is comprised of 10 manned runs and an unmanned corn-man run. Six test subjects, including four astronauts, will participate. The test objective is to evaluate ability xEMU Demo architecture to perform ISS microgravity tasks. Each crew members will complete both a familiarization run and a nominal EMU EVA timeline run. Qualitative and quantitative data will be collected to aid the assessment of the suit. Preliminary feedback from astronauts who have completed the test series evaluate the xEMU Demo architecture as acceptable to complete a demonstration mission on the ISS.Item Testing the Exploration Conops(Excon) Mockup Suit in Lunar Analog Environments in 2022(2023 International Conference on Environmental Systems, 2023-07-16) Tejral, Zachary; Flaspohler, Christine; Keomany, Tommy; Graff, Trevor; Fester, Zachary; Davis, Kristine; Coan, DaveUnderstanding how to effectively train for Extravehicular Activities (EVAs) for Artemis missions is critical. Developing high-fidelity simulation environments is important for Artemis mission preparation. Because the actual Lunar exploration environment cannot be fully replicated on Earth, it is paramount to determine where and how to properly train the Artemis team. The overall focus for this test series was developing the capability to perform Artemis simulated EVAs in high-fidelity, full-scale environments. This test series was broken into 3 distinct tests titled after the EHP integrated test team: Joint EVA Test Team (JETT). The test locations are planned to serve as Artemis training sites and were selected because of their relevance to the expected Artemis Lunar terrain. JETT1 was conducted near Kilbourne Hole by El Paso, Texas and focused on hardware development and checkout. JETT2 was conducted in the Icelandic Highlands and began the transition towards EVA concept operations (con-ops), risks and technology. JETT3 was conducted near SP Crater by Flagstaff Arizona and focused on simulating the Artemis III mission with a simulated Houston based Flight Control Team (FCT) and a Science Mission Directorate (SMD) science team. All three JETT tests utilized the Excon mockup space suit. The Excon mockup suit is a light-weight, unpressurized Exploration Extravehicular Mobility Unit (xEMU) simulator. While it cannot replicate the feel of working within a pressurized suit, it does introduce similar volume constraints and some of the mobility programing to simulate the user experience in the xEMU. Overall, the JETT testing was able to create a simulated Lunar EVA and have two subjects perform full scale operations in line with Artemis III mission expectations. Future work is planned to continue to improve the simulation quality of Lunar EVA simulations.Item xEMU Lower Torso Assembly (LTA) Brief Fleet Sizing Study(2020 International Conference on Environmental Systems, 2020-07-31) Davis, Kristine; Rhodes, Richard; Kim, Han; Benson, Elizabeth; Hernandez, Yaritza; Vu, Linh; Rajulu, SudhakarThe Exploration Extravehicular Mobility Unit (xEMU) project is tasked with building a spacesuit for the lunar 2024 missions. These missions will require a mobile Lower Torso Assembly (LTA) to fit the required range of astronauts’ anthropometry with optimal mobility. The goal of this work is to predict the proportion of the current and projected crew population accommodated by the new LTA design. Initially, virtual fit checks were conducted via CAD modeling. Body shape manikins were iteratively positioned inside the CAD geometry. The resultant suit-to-body contact and overlap was quantified and used to develop a statistical model to predict the probability of fit. Twenty test subjects whose predicted fit is at a borderline level are currently being assessed. The subjects don/doff a 3D printed LTA mockup, and perform basic functional movements, including walking, kneeling and squatting. 3D scans are recorded, and a questionnaire is administered for the overall fit and any discomfort locations. The statistical model will be updated using the physical test outcome and projected to a large database of approximately 2000 male and 1000 female body shapes from the US Army. The model will estimate the overall proportion of the accommodated population to characterize the anthropometry of the crew who would fit in the LTA. This will determine if the current LTA sizing is adequate to meet the xEMU requirements.