Engineering topics
Publications and source records attributed to Orndoff, Evelyne.
The 2020 exploration atmosphere and EVA prebreathe protocol validation will be the first test in elevated oxygen since the Skylab Medical Experiment Altitude Test (SMEAT).
The National Aeronautics and Space Administration (NASA) has led the development of unique flame retardant fibers for the specific requirements of different space programs. Three of these fibers have greatly contributed to the safety of all the space missions since the Apollo program. Beta alumina-silica microfiber developed for the outer layer of the space suit after the Apollo 1 fire is no longer used and has been replaced by other glass fibers. Expanded polytetrafluoroethylene (e-PTFE) fiber used in the current spacesuit is mostly known today through its trade mark Gore-Tex®. Polybenzimidazole (PBI) filament fiber used in many applications from the Apollo to the Space Shuttle program is no longer available. More recently, TOR"TM" copolymer of polyimide fiber developed during the space shuttle program to resist the atomic oxygen present in Low Earth Orbit has been barely used. The high cost and narrow range of aeronautical and aerospace applications have, however, led to a limited production of these fibers. Only fibers that found niche markets survived. Yet, deep space exploration will require more of these inherently flame retardant fibers than what is available today. There is a need for new flame retardant fabrics inside the space vehicles as well as a need for logistics reduction for long term space missions. Materials like modacrylic and polyimide are good candidates for future flame retardant aerospace fabrics. New fabrics must be developed for astronauts' clothing, as well as crew quarters and habitat. Therefore, both staple and filament fibers of various linear densities are needed for a three years mission to Mars.
The National Aeronautics and Space Administration (NASA) has led in the development of unique flame retardant fibers for human spaceflight since the beginning of the Apollo program. After the Apollo 1 fire which killed Command Pilot Virgil I 'Gus' Grissom, Senior Pilot Edward H. White II, and Pilot Roger B. Chaffee from cardiac arrest on January 27, 1967, the accident investigators found severe third degree burns and melted spacesuits on the astronauts bodies. NASA immediately initiated an extensive research program aimed at developing flame retardant and flame resistant fibers for the enriched oxygen atmosphere of the Apollo crew cabin. Fibers are flame retardant when they have been modified by chemical and thermal treatments. Fibers are flame resistant when they are made of inherently flame resistant materials (i.e. glass, ceramic, highly aromatic polymers). Immediately after this tragic accident, NASA funded extensive research in specifically developing flame retardant fibers and fabrics. The early developmental efforts for human spaceflight were for the outer layer of the Apollo spacesuit. It was imperative that non-flammable fabrics be used in a 100% oxygen environment. Owens-Corning thus developed the Beta fiber that was immediately used in the Apollo program and later in the Space Shuttle program. Aside from the urgent need for protective fabrics for the spacesuit, NASA also needed flame retardant fabrics for both clothing and equipment inside the spacecraft. From the mid-1960s to the early 1980's, NASA contracted with many companies to develop inherently flame retardant fibers and flame retardant finishes for existing fibers. Fluorocarbons and aromatic polyamides were the polymers of great interest for the development of new inherently flame retardant fibers for enriched oxygen environments. These enriched environments varied for different space programs. For example, the Apollo program requirements were for materials that would not support combustion in a 70%/30% oxygen/nitrogen environment at 6.3 pounds per square inch (psi). The Skylab program flammability requirements were set at 80%/20% oxygen/nitrogen ratios at 5 psi. While many fibers produced under several NASA contracts were never used, a few have become commercial products. The intent of this paper is to present the developmental history of some of these new or modified textile fibers. These developmental efforts are presented at various levels of details depending on the source of the historical records.
This report covers the use of ozone and mist with detergent to develop zero-gravity laundering technology. Different concentrations of detergent with and without ozone were applied to remove odor from t-shirts used during exercise. The fabrics of these shirts were categorized into two groups: hydrophobic (polyester and modacrylic) and hydrophilic (cotton and Merino wool). It was found that applying detergent solution as a mist sufficient to achieve saturation can be effective in eliminating odors from athletically soiled shirts either with or without exposure to ozone.
Astronaut clothes for exploration missions beyond low Earth orbit need to satisfy several challenges not met by the currently-used mostly-cotton clothing. A laundering system is not expected to be available, and thus soiled garments must be trashed. Jettisoning waste does not seem feasible at this time. The cabin oxygen concentration is expected to be higher than standard, and thus fabrics must better resist ignition and burning. Fabrics need to be identified that reduce logistical mass, that can be worn longer before disposal, that are at least as comfortable as cotton, and that resist ignition or that char immediately after ignition. Human factors and psychology indicate that crew well-being and morale require a variety of colors and styles to accommodate personal identity and preferences. Over the past four years, the Logistics Reduction Project under NASA's Advanced Exploration Systems Program has sponsored the Advanced Clothing System Task to conduct several ground studies and one ISS study. These studies have evaluated length of wear and personal preferences of commercially-available exercise- and routine-wear garments made from several fabrics (cotton, polyester, Merino wool, and modacrylic), woven and knitted. Note that Merino wool and modacrylic char like cotton in ambient air, while polyester unacceptably melts. This paper focuses on the two components of an International Space Station study, onboard and on the ground, with astronauts and cosmonauts. Fabrics were randomized to participants. Length of wear was assessed by statistical survival analysis, and preference by exact binomial confidence limits. Merino wool and modacrylic t-shirts were worn longer on average than polyester t-shirts. Interestingly, self-assessed preferences were inconsistent with length-of-wear behavior, as polyester was preferred to Merino wool and modacrylic.
The goal of the Advanced Clothing System (ACS) is to use advanced commercial off-theshelf fibers and antimicrobial treatments with the goal of directly reducing the mass and volume of a logistics item. The current clothing state-of-the-art on the International Space Station (ISS) is disposable, mostly cotton-based, clothing with no laundry provisions. Each clothing article has varying use periods and will become trash. The goal is to increase the length of wear of the clothing to reduce the logistical mass and volume. The initial focus has been exercise clothing since the use period is lower. Various ground studies and an ISS technology demonstration have been conducted to evaluate clothing preference and length of wear. The analysis indicates that use of ACS selected garments (e.g. wool, modacrylic, polyester) can increase the breakeven point for laundry to 300 days.
The goal of the Advanced Clothing System (ACS) is to use advanced commercial off-the-shelf fibers and antimicrobial treatments with the goal of directly reducing the mass and volume of a logistics item. The current clothing state-of-the-art on the International Space Station (ISS) is disposable, mostly cotton-based, clothing with no laundry provisions. Each clothing article has varying use periods and will become trash. The goal is to increase the length of wear of the clothing to reduce the logistical mass and volume. The initial focus has been exercise clothing since the use period is lower. Various ground studies and an ISS technology demonstration have been conducted to evaluate clothing preference and length of wear. The analysis indicates that use of ACS selected garments (e.g. wool, modacrylic, polyester) can increase the breakeven point for laundry to 300 days.
All human space missions require significant logistical mass and volume that will become an excessive burden for long duration missions beyond low Earth orbit. The current International Space Station (ISS) crew wardrobe has already evolved not only to reduce some of the logistical burden but also to address crew preference. The present study was undertaken to find ways further to reduce this logistical burden while examining human response to different types of clothes. The primary objective of the study is to measure how long people can wear the same exercise garment, depending on the type of fabric and the presence of antimicrobial treatment. The secondary objective is to assess the reasons for length of wear from perceptions of clothing characteristics, including nine ordinal scales. Cardiovascular exercise was chosen as the activity in this experiment for its profuse sweating effect and because it is considered a more severe treatment applied to the clothes than every-day usage. Study garments were exercise T-shirts and shorts purchased from various vendors. Fabric construction, fabric composition, and finishing treatment were defined as the key variables. A web-based questionnaire was used for self-reported data collection. The study was divided in three balanced experiments: a cotton-polyester-wool (CPW) T-shirts study with 61 participants, a polyester-modacrylic-polyester/cocona (PMC) T-shirts study with 40 participants, and a shorts study with 70 participants. In the CPW study, the T-shirts were made of 100% cotton, or of 100% polyester or of 100% wool, and categorized into open and tight knit constructions. In the PMC study, the T-shirts were made of 100% polyester, or of 82% modacrylic, or of 95% polyester with 5% cocona fiber, without construction distinction. The shorts were made either of 100% cotton or of 100% polyester, and were knitted or woven. Some garments were treated with Bio-Protect 500 antimicrobial finish according the experimental design. The data collected from the questionnaire included garment identification, level of exertion, duration of exercise session, number of exercise sessions, an ordinal preference scale for nine sensory elements, and reason for retiring a used garment. From the analysis of the combined CPW and PMC shirt studies, there are statistically significant differences among the mean lifetimes of various types of shirts. The exercise shirts with the longest mean lifetimes are untreated wool (600 minutes), treated cotton (526 minutes), and untreated modacrylic (515 minutes). From the combined CPW and PMC shirt studies, the most preferred material was untreated open-knit wool, which is one of the two materials that jointly were worn the longest, untreated wool, both open-knit and tight-knit. For the CP shorts study, there were no statistically significant differences in mean lifetimes of the exercise shorts at the 5% significance level due to the treatment combinations. There was therefore no justification to examine differences among levels of main effects or interactions. The preference for shorts was in this order: untreated woven polyester, untreated knitted polyester, untreated woven cotton, and treated knitted cotton.The nine preference scales were tabulated to determine the preference responses at the end of those exercise periods which were prior to the period when a garment was retired and a new garment was started. The assumption is that an unfavorable assessment of a garment leads to its retirement. The scent scale response was predominantly unfavorable at the end of the exercise period immediately prior to the exercise period when a new garment was started. Additional work on wool clothing is needed to assess if this material can be part of a crew wardrobe for long duration missions. The results of this study informed the choice of fabrics for an upcoming ISS intra-vehicular clothing study.
All human space missions require significant logistical mass and volume that add an unprecedented burden on longduration missions beyond low-Earth orbit. For these missions with limited cleaning resources, a new wardrobe must be developed to reduce this logistical burden by reducing clothing mass and extending clothing wear. The present studies have been undertaken, for the first time, to measure length of wear and to assess the acceptance of such extended wear. Garments in these studies are commercially available exercise T-shirts and shorts, routine-wear T-shirts, and longsleeved pullover shirts. Fabric composition (cotton, polyester, light-weight, superfine Merino wool, modacrylic, cotton/rayon, polyester/Cocona, modacrylic/Xstatic, modacrylic/rayon, modacrylic/lyocell/aramid), construction (open knit, tight knit, open weave, tight weave), and finishing treatment (none, quaternary ammonium salt) are the independent variables. Eleven studies are reported here: five studies of exercise T-shirts, three of exercise shorts, two of routine wear Tshirts, and one of shirts used as sleep-wear. All studies are conducted in a climate-controlled environment, similar to a space vehicle's. For exercise clothing, study participants wear the garments during aerobic exercise. For routine wear clothing, study participants wear the T-shirts daily in an office or laboratory. Daily questionnaires collected data on ordinal preferences of nine sensory elements and on reason for retiring a used garment. Study 1 compares knitted cotton, polyester, and Merino exercise T-shirts (61 participants), study 2, knitted polyester, modacrylic, and polyester/Cocona exercise T-shirts (40 participants), study 3, cotton and polyester exercise shorts, knitted and woven (70 participants), all three using factorial experimental designs with and without a finishing treatment, conducted at the Johnson Space Center, sharing study participants. Study 4 compares knitted polyester and ZQ Merino exercise T-shirts, study 5, knitted ZQ Merino and modacrylic routine-wear T-shirts, with study 6 using only knitted polyester exercise shorts. No finishing treatment is used. Studies 4 and 5 use cross-over experimental designs, and all three studies were conducted aboard the ISS with six crew. Studies 4 and 6 were repeated on the ground with the same participants to learn if perception was affected microgravity. Study 7 is a longer-term, single-blind panel study of knitted routine-wear undershirts with at least 12 participants to assess tolerance to Merino by comparing it with a cotton/rayon blends, using a cross-over design, eliminating carryover effects with wash-out periods between shirts.
All human space missions require significant logistical mass and volume that will become an excessive burden for long duration missions beyond low Earth orbit. The goal of the Advanced Exploration Systems (AES) Logistics Reduction & Repurposing (LRR) project is to bring new ideas and technologies that will enable human presence in farther regions of space. The LRR project has five tasks: 1) Advanced Clothing System (ACS) to reduce clothing mass and volume, 2) Logistics to Living (L2L) to repurpose existing cargo, 3) Heat Melt Compactor (HMC) to reprocess materials in space, 4) Trash to Gas (TTG) to extract useful gases from trash, and 5) Systems Engineering and Integration (SE&I) to integrate these logistical components. The current International Space Station (ISS) crew wardrobe has already evolved not only to reduce some of the logistical burden but also to address crew preference. The ACS task is to find ways to further reduce this logistical burden while examining human response to different types of clothes. The ACS task has been broken into a series of studies on length of wear of various garments: 1) three small studies conducted through other NASA projects (MMSEV, DSH, HI-SEAS) focusing on length of wear of garments treated with an antimicrobial finish; 2) a ground study, which is the subject of this report, addressing both length of wear and subject perception of various types of garments worn during aerobic exercise; and 3) an ISS study replicating the ground study, and including every day clothing to collect information on perception in reduced gravity in which humans experience physiological changes. The goal of the ground study is first to measure how long people can wear the same exercise garment, depending on the type of fabric and the presence of antimicrobial treatment, and second to learn why. Human factors considerations included in the study consist of the Institutional Review Board approval, test protocol and participants' training, and a web-based data collection questionnaire. Cardiovascular exercise was chosen as the activity in this experiment for its profuse sweating effect and because it is considered a more severe treatment applied to the clothes than every-day usage. Study garments were exercise T-shirts and shorts purchased from various vendors. Fabric construction, fabric composition, and finishing treatment were defined as the key variables. The study was divided into three balanced experiments: a cotton-polyester-wool (CPW) T-shirts study with 61 participants, a polyester-modacrylic-polyester/cocona (PMC) T-shirts study with 40 participants, and a shorts study with 70 participants. In the CPW study, the T-shirts were made of 100% cotton, or of 100% polyester or of 100% wool, and categorized into open and tight knit constructions. In the PMC study, the T-shirts were made of 100% polyester, or of 82% modacrylic, or of 95% polyester with 5% cocona fiber, without construction distinction. The shorts were made either of 100% cotton or of 100% polyester, and were knitted or woven. Some garments were treated with Bio-Protect 500 antimicrobial finish according to the experimental design. The data collected from the questionnaire included garment identification, level of exertion, duration of exercise session, number of exercise sessions, an ordinal preference scale for nine sensory elements, and reason for retiring a used garment. From the analysis of the combined CPW and PMC shirt studies, there are statistically significant differences among the mean lifetimes of various types of shirts. The exercise shirts with the longest mean lifetimes are untreated wool (600 minutes), treated cotton (526 minutes), and untreated modacrylic (515 minutes). From the combined CPW and PMC shirt studies, the most preferred material was untreated open-knit wool, which is one of the two materials that jointly were worn the longest, untreated wool, both open-knit and tight-knit. For the CP shorts study, there were no statistically significant differences in mean lifetimes of the exercise shorts at the 5% significance level due to the treatment combinations. There was therefore no justification to examine differences among levels of main effects or interactions. The preference for shorts was in this order: untreated woven polyester, untreated knitted polyester, untreated woven cotton, and treated knitted cotton. The nine preference scales were tabulated to determine the preference responses at the end of those exercise periods which were prior to the period when a garment was retired and a new garment was started. The assumption is that an unfavorable assessment of a garment leads to its retirement. The scent scale response was predominantly unfavorable at the end of the exercise period immediately prior to the exercise period when a new garment was started.
This paper outlines a preliminary study that was conducted to review, test, and improve on current space suit biocontamination control. Biocontamination from crew members can cause space suit damage and objectionable odors and lead to crew member health hazards. An understanding of the level of biocontamination is necessary to mitigate its effects. A series of tests were conducted with the intent of evaluating current suit materials, ground and on-orbit disinfectants, and potential commercial off-the-shelf antimicrobial materials. Included in this paper is a discussion of the test methodology, results, and analysis method.
Several candidate advanced pressure bladder membrane materials have been developed for NASA Johnson Space Center by DSM Biomedical for selective permeability of carbon dioxide and water vapor. These materials were elasthane and two other formulations of thermoplastic polyether polyurethane. Each material was tested in two thicknesses for permeability to carbon dioxide, oxygen and water vapor. Although oxygen leaks through the suit bladder would amount to only about 60 cc/hr in a full size suit, significant amounts of carbon dioxide would not be rejected by the system to justify its use. While the ratio of carbon dioxide to oxygen permeability is about 48 to 1, this is offset by the small partial pressure of carbon dioxide in acceptable breathing atmospheres of the suit. Humidity management remains a possible use of the membranes depending on the degree to which the water permeability is inhibited by cations in the sweat. Tests are underway to explore cation fouling from sweat.
Three methods are being developed for keeping water from freezing during high-altitude climbs so that mountaineers can remain hydrated. Three strategies have been developed. At the time of this reporting two needed to be tested in the field and one was conceptual. The first method is Passive Thermal Control Using Aerogels. This involves mounting the fluid reservoir of the climber s canteen to an inner layer of clothing for better heat retention. For the field test, bottles were mounted to the inner fleece layer of clothing, and then aerogel insulation was placed on the outside of the bottle, and circumferentially around the drink straw. When climbers need to drink, they can pull up the insulated straw from underneath the down suit, take a sip, and then put it back into the relative warmth of the suit. For the field test, a data logger assessed the temperatures of the water reservoir, as well as near the tip of the drink straw. The second method is Passive Thermal Control with Copper-Shielded Drink Straw and Aerogels, also mounted to inner layers of clothing for better heat retention. Braided wire emanates from the inside of the fleece jacket layer, and continues up and around the drink straw in order to use body heat to keep the system-critical drink straw warm enough to keep water in the liquid state. For the field test, a data logger will be used to compare this with the above concept. The third, and still conceptual, method is Active Thermal Control with Microcontroller. If the above methods do not work, microcontrollers and tape heaters have been identified that could keep the drink straw warm even under extremely cold conditions. Power requirements are not yet determined because the thermal environment inside the down suit relative to the external environment has not been established. A data logger will be used to track both the external and internal temperatures of the suit on a summit day.
This design of the liquid-cooling garment for NASA spacesuits allows the suit to remove metabolic heat from the human body more effectively, thereby increasing comfort and performance while reducing system mass. The garment is also more flexible, with fewer restrictions on body motion, and more effectively transfers thermal energy from the crewmember s body to the external cooling unit. This improves the garment s performance in terms of the maximum environment temperature in which it can keep a crewmember comfortable. The garment uses flexible, highly thermally conductive sheet material (such as graphite), coupled with cooling water lines of improved thermal conductivity to transfer the thermal energy from the body to the liquid cooling lines more effectively. The conductive sheets can be layered differently, depending upon the heat loads, in order to provide flexibility, exceptional in-plane heat transfer, and good through-plane heat transfer. A metal foil, most likely aluminum, can be put between the graphite sheets and the external heat source/sink in order to both maximize through-plane heat transfer at the contact points, and to serve as a protection to the highly conductive sheets. Use of a wicking layer draws excess sweat away from the crewmember s skin and the use of an outer elastic fabric ensures good thermal contact of the highly conductive underlayers with the skin. This allows the current state of the art to be improved by having cooling lines that can be more widely spaced to improve suit flexibility and to reduce weight. Also, cooling liquid does not have to be as cold to achieve the same level of cooling. Specific areas on the human body can easily be targeted for greater or lesser cooling to match human physiology, a warmer external environment can be tolerated, and spatial uniformity of the cooling garment can be improved to reduce vasoconstriction limits. Elements of this innovation can be applied to other embodiments to provide effective heat transfer over a flexible and surface-conformable fashion without the limitation of fluid freeze points.
Water vapor permeability is shown to be useful in rejecting heat and managing moisture accumulation in launch-and-entry pressure suits. Currently this is accomplished through a porous Gortex layer in the Advanced Crew and Escape Suit (ACES) and in the baseline design of the Constellation Suit System Element (CSSE) Suit 1. Non-porous dense monolithic membranes (DMM) that are available offer potential improvements for water vapor permeability with reduced gas leak. Accordingly, three different pressure bladder materials were investigated for water vapor permeability and oxygen leak: ElasthaneTM 80A (thermoplastic polyether urethane) provided from stock polymer material and two custom thermoplastic polyether urethanes. Water vapor, carbon dioxide and oxygen permeability of the DMM's was measured in a 0.13 mm thick stand-alone layer, a 0.08 mm and 0.05 mm thick layer each bonded to two different nylon and polyester woven reinforcing materials. Additional water vapor permeability and mechanical compression measurements were made with the reinforced 0.05 mm thick layers, further bonded with a polyester wicking and overlaid with moistened polyester fleece thermal underwear .This simulated the pressure from a supine crew person. The 0.05 mm thick nylon reinforced sample with polyester wicking layer was further mechanically tested for wear and abrasion. Concepts for incorporating these materials in launch/entry and Extravehicular Activity pressure suits are presented.
This paper describes the effort and accomplishments for developing flexible fabrics with high thermal conductivity (FFHTC) for spacesuits to improve thermal performance, lower weight and reduce complexity. Commercial and additional space exploration applications that require substantial performance enhancements in removal and transport of heat away from equipment as well as from the human body can benefit from this technology. Improvements in thermal conductivity were achieved through the use of modified polymers containing thermally conductive additives. The objective of the FFHTC effort is to significantly improve the thermal conductivity of the liquid cooled ventilation garment by improving the thermal conductivity of the subcomponents (i.e., fabric and plastic tubes). This paper presents the initial system modeling studies, including a detailed liquid cooling garment model incorporated into the Wissler human thermal regulatory model, to quantify the necessary improvements in thermal conductivity and garment geometries needed to affect system performance. In addition, preliminary results of thermal conductivity improvements of the polymer components of the liquid cooled ventilation garment are presented. By improving thermal garment performance, major technology drivers will be addressed for lightweight, high thermal conductivity, flexible materials for spacesuits that are strategic technical challenges of the Exploration