Keywords: spacecraft design, micrometeoroids, space debris, shielding, protection
Abstract: Spacecraft are subject to micro-meteoroid and orbital debris (MMOD) impact damage which have the potential to degrade performance, shorten the mission, or result in catastrophic loss of the vehicle. Specific MMOD protection requirements are established by NASA for each spacecraft early in the program/project life to ensure the spacecraft meets desired safety and mission success goals. Both the design and operations influences spacecraft survivability in the MMOD environment, and NASA considers both in meeting MMOD protection requirements. The purpose of this handbook is to provide spacecraft designers and operations personnel with knowledge gained by NASA in implementing effective MMOD protection for the International Space Station (ISS), Space Shuttle, and various science spacecraft. It has been drawn from a number of previous publications, as well as new work. This handbook documents design and operational methods to reduce MMOD risk. In addition, this handbook describes tools and equations needed to design proper MMOD protection. It is a living report in that it will be updated and re-released periodically in future with additional information.
Keywords: light sources, lighting equipment, aircraft lights, illuminating, US Laboratory Module
Abstract: Solid state lights (SSLs) are being developed to potentially replace the general luminaire assemblies (GLAs) currently in service in the ISS and included in designs of modules for the ISS. The SSLs consist of arrays of light emitting diodes (LEDs), small solid state electronic devices that produce visible light in proportion to the electrical current flowing through them. Recent progressive advances in electrical power-to-light conversion efficiency in LED technology have allowed the consideration of LEDs as replacements for incandescent and fluorescent light sources in many circumstances, and their inherent advantages in ruggedness, reliability, and life expectancy make them attractive for applications in spacecraft. One potential area of application for the SSLs is in the US Laboratory Module of the ISS. This study addresses the suitability of the SSLs as replacements for the GLAs in this application.
Keywords: International Space Station; research facilities; bioastronautics; space technology experiments; biology; physical science, space flight; technology assessment
Abstract: This report summarizes research accomplishments on the International Space Station (ISS) through the first 15 Expeditions. When reseach programs for early Expeditions were established, five administrative organizations were executing research on ISS: bioastronautics research, fundamental space biology, physical science, space product development, and space flight. The Vision for Space Exploration led to changes in NASA's administrative structures, so we have grouped experiments topically by scientific themes--human research for exploration, physical and biological sciences, technology development, observing the Earth, and educating and inspiring the next generation--even when these do not correspond to the administrative structure at the time at which they were completed. The research organizations at the time at which the experiments flew are preserved in the appendix of this document. These investigations on the ISS have laid the groundwork for research planning for Expeditions to come. Humans performing scientific investigations on ISS serve as a model for the goals of future Exploration missions. The success of a wide variety of investigations is an important hallmark of early research on ISS. Of the investigations summarized here, some are completed with results released, some are completed with preliminary results, and some remain ongoing.
Keywords: Skylab 1; Skylab 2; Skylab 3; Skylab program; long duration space flight; life sciences; astronomy; solar physics; materials science; Earth observations; extravehicular activity
Abstract: From May 1973 to February 1974, NASA conducted a series of three human missions to the Skylab space station, which was a voluminous vehicle largely descendant of Apollo hardware and the first U.S. space station. Crew members of these missions spent record-breaking durations of time in microgravity (28, 59, and 84 days, respectively) and gave the U.S. space program its first experiences with long-duration space flight. The program overcame a number of obstacles to conduct a lauded scientific program that encompassed life sciences, astronomy, solar physics, materials sciences, and Earth observations. Yet Skylab has more to offer than the results of these scientific efforts. The operations that were conducted by the crews and ground personnel represent a rich legacy of operational experience. As we plan a return to the moon and subsequent human exploration of Mars, it is essential to use the experiences and insights of those who were involved in previous programs. Skylab and Skylab Medical Experiments Altitude Test personnel possess unique insight into operations that are being planned for the Constellation Program, such as umbilical extravehicular activity and water landing/recovery of long-duration crew members. The Skylab Program was also well known for its habitability and extensive medical suite.
Keywords: lunar dust; lunar exploration; Apollo 12 flight; Apollo 16 flight; Apollo 17 flight; space suits; extravehicular mobility units; lunar soil; lunar dust; pyroxenes; feldspars
Abstract: Crew-worn systems/components of Apollo spacesuits were studied to determine contamination, abrasion, and wear or loss of function due to lunar soil particles. Materials studied included outermost soft fabric layers on Apollo 12 and 17 integrated thermal micrometeorite garment assemblies and outermost fabrics on Apollo 17 extravehicular pressure gloves. Scanning electron microscope (SEM) examination of Apollo 12 T-164 woven Teflon« fabric confirms that lunar-soil particles separated and frayed the fibers. Optical imaging, chemical analysis, and particle sampling of the outer fabric of the Apollo 17 spacesuit identified Ti as a potentially useful chemical marker for comparing the amount of lunar soil retained on spacesuit outer fabric. High-yield particle sampling determined that 80% of particles were lunar soil, averaging 10.5 Ám in diameter, consisting of plagioclase feldspar and various glassy particles, with a subordinate amount of pyroxene. Pyroxene particles seem to have better retention on the spacesuit outer fabric. SEM examination revealed no measurable difference in wear and abrasion in the wrist rotation bearing on an Apollo 16 pressure glove worn only in the vehicle with one worn only on the moon; either the bearing prevented entry of lunar dust, or the dust was insufficiently abrasive to damage the bearing, or both.
Keywords: gloves; protective clothing;e xtravehicular activity; micrometeoroids; fabrics; multilayer insulation; reinforcing materials; impact damage; reinforcing fibers
Abstract: Cut damages to crew member extravehicular mobility unit (EMU) gloves during extravehicular activity (EVA) on board the International Space Station (ISS) resulted from contact with sharp edges or pinch points. One possible source of cut-hazards is protruding sharp-edged crater lips that result from the impact of micrometeoroid and orbital debris (MMOD) particles in external metallic handrails along EVA translation paths. During hypervelocity impact of MMOD particles, an evacuation flow develops behind the shockwave, resulting in the formation of crater lips that can protrude above the target surface. In this study, two modifications to ISS handrails were evaluated to limit EMU glove cut-hazards due to MMOD impact craters. In the first phase, four flexible overwrap configurations were evaluated. All four overwrap configurations proved effective in limiting contact between EMU gloves and impact crater profiles, but the multilayer Beta-cloth configuration proved the most effective. In the second phase of the study, four material alternatives to current aluminum and stainless-steel alloys were evaluated. Of the four, only fiberglass formed a less-hazardous damage profile than the baseline metallic target. In parallel with EMU glove redesign efforts, modifications to metallic ISS handrails provide the means by which to significantly reduce cut-hazards from MMOD impact craters.
Keywords: computer programs; health; radiation sickness; radiation absorption; computer aided design
Abstract: This document provides a manual for users who wish to operate the Pro/ENGINEERING (ProE) Wildfire 3.0 with the NASA Space Radiation Program custom-designed toolkit, "Fishbowl," for ray-tracing of complex spacecraft geometries that are given by a ProE CAD model. The analysis of spacecraft geometry through ray-tracing is a vital part in the calculation of health risks from space radiation. Space radiation poses severe risks of cancer, degenerative diseases, and acute radiation sickness during long-term exploration missions, and shielding optimization is an important component in the applicatino of radiation risk models. Ray-tracking is a technique in which 3D vehicle geometry can be represented as the input for the space radiation transport code and subsequent risk calculations. This manual will first list, for the user, the contact information for help in installing ProE and Fishbowl in addition to notes on platform support and system requirements information. The document will then show the user how to use the software to ray-trace a ProE-designed 3D assembly, and will serve later as a reference for troubleshooting. The user is assumed to have previous knowledge of ProE and CAD modeling.
Keywords: computer programs, software engineering; shielding; micrometeoroids; space debris; hypervelocity projectiles; impact damage; meteoritic damage
Abstract: A software program has been developed that enables the user to quickly and simply perform ballistic limit calculations for shield configurations that are subject to hypervelocity meteoroid/orbital debris (MMOD) impacts. This analysis program consists of two core modules: a design module and a performance module. The design module enables a user to calculate preliminary dimensions of a shield configuration (e.g., thicknesses/areal densities, spacing, etc.) for a "design" particle (diameter, density, impact velocity, incidence). The performance module enables a more detailed shielding analysis, providing the performance of a user-defined shielding configuration over the range of relevant in-orbit impact conditions.
Keywords: shielding; spacecraft shielding; micrometeoroids; space debris; foams; metal foams; impact damage; damage; hypervelocity impact
Abstract: The presence of honeycomb core in a multi-wall shielding configuration for protection against micrometeoroid and orbital debris (MMOD) particle impacts at hypervelocity is generally considered detrimental as the cell walls act to restrict fragment cloud expansion, creating a more concentrated load on the shield rear wall. As mission requirements often prevent the inclusion of a dedicated MMOD shield, structural honeycomb sandwich panels are among the most prevalent shield types. Open-cell metallic foams are a relatively new material with novel mechanical and thermal properties that have shown promising results in preliminary hypervelocity impact shielding evaluations. In this study, an International Space Station-representative MMOD shielding configuration has been modified to evaluate the potential performance enhancement gained by substituting honeycomb for open-cell foam. The baseline shielding configuration consists of a double-mesh outer layer, two honeycomb sandwich panels, and an aluminum rear wall. In the modified configuration, the two honeycomb cores are replaced by open-cell foam. To compensate for the heavier core material, facesheets have been removed from the second sandwich panel in the modified configuration. Twenty-one tests are reported on the double-layer honeycomb and double-layer foam configurations; and previously identified weaknesses have been investigated and found to be negligible for the double-layer configuration.
Keywords: weightlessness; weightlessness simulation; parabolic flight; zero gravity; aerospace medicine; astronaut performance; bioprocessing; space manufacturing
Abstract: This document represents a summary of medical and scientific evaluations conducted aboard the C-9 and other NASA-sponsored aircraft from June 2008 to June 2009. Included is a general overview of investigations manifested and coordinated by the Human Adaptation and Countermeasures Division. A collection of brief reports that describe tests conducted aboard the NASA-sponsored aircraft follows the overview. Principal investigators and test engineers contributed significantly to the content of this report, describing their particular experiment or hardware evaluation. Although this document follows general guidelines, each report format may vary to accommodate differences in experiment design and procedures. This document concludes with an appendix that provides background information concerning the Reduced Gravity Program.
Keywords: human performance data, 10-km ambulation, EVA Walkback, EWT, MKIII suit, space suit design
Abstract: The primary objective was to collect human performance data regarding the feasibility of a suited 10-km walkback to a habitat in the event of a failed rover. All subjects completed the walkback in less than 2 hours and with little difficulty. A secondary objective was to understand human performance limitations of the suit. Preliminary analysis indicated that metabolic cost was significant. Weight-matched unsuited trials provided an initial estimate of metabolic cost of increased suit weight. But additional factors could not be isolated, and additional tests will be needed. Results of this test also clearly indicate that crew members in the MKIII suit may eprform well on the moon but may not perform well on Mars due to the increased gravity. In the Mars-related trials, subjects rapidly approached near-maximal physiolgic effort while brisk walking. Another secondary objective was proving human performance and suit biomechanical data for use in the suit and PLSS design. The data provide a critical step forward to understanding and quantifying suited human performance in reduced gravity. Future studies will be needed to foster a thorough understanding of how human performance is affected by extravehicular activity suits and reduced-gravity environments.
Keywords: astronaut performance; risk; biological effects; safety; boredom; emotional factors; physiological effects; psychological effects; interpersonal relations; human tolerances
Abstract: The Human Research Program (HRP), which is within the NASA Exploration Systems Mission Directorate, is a directed and applied research program that addresses agency needs for human health and performance risk mitigation strategies in support of space exploration as described in the Vision for Space Exploration, the U.S. National Space Policy, and the NASA Strategic Plan. These exploration undertakings include missions to the moon and Mars. Although all of them will involve some of the same human health and performance challenges, each mission also will include specific challenges that depend on the nature of the exact undertaking and the development schedule. Accordingly, HRP research and technology development are focused on the highest-priority risks to crew health and safety, with the goal of ensuring mission success and maintaining long-term crew health.
Keywords: aerospace medicine; air quality; radiation protection; hypergolic rocket propellants; fuel cells; robotics; software development tools; test equipment; comets, nondestructive tests
Abstract: The Biennial Research and Technology Development Report highlights the diverse technical, scientific, and engineering research and technology development under way at the Johnson Space Center (JSC). The articles contained within this report further JSC's and NASA's historical tradition of working with colleges and universities, industry, federal laboratories, and other research and technology development organizations for the betterment of humankind. The report is organized into nine broad categories: (1) human health and medicine, including analog medical research (e.g., medical issues in Antarctica) as well as new, cutting-edge medical technologies; (2) environmental technology (e.g., recycling and recovery technologies, air quality monitoring, and radiation protection research; (3) materials development and testing (e.g., new developments in nondestructive evaluation tests, single-wall carbon nanotube growth); (4) flammability and explosion testing, including protection and testing standards; (5) power, battery, and propulsion technologies (e.g., NASA fuel cells and high-sensitivity measurements for permeation of hypergol); (6) robotics and automation technologies; (7) technologies for harsh environments, including extravehicular activity technologies; (8) space and ground operations (e.g., software developments for space station operations, data mining, and a low-impact docking system); and (9) planetary sciences (i.e., new discoveries of cometary particle, results from planetary and rover research, and educational and outreach initiatives).
Keywords: muscle; microgravity; knee; ankle; trunk; concentric; eccentric
Abstract: To assess changes in muscular strength and endurance after microgravity exposure, NASA measures isokinetic strength and endurance across multiple sessions before and after long-duration spaceflight. Accurate interpretation of pre- and post-flight measures depends on the reliability of each measure. The purpose of this study was to evaluate the test-retest reliability of the ISS Isokinetic Protocol. Twenty-four subjects volunteered to participate. Isokinetic knee, ankle, and trunk flexion and extension strength as well as endurance of the knee flexors and extensors were measured during four weekly sessions. Repeated measures ANOVA were used to identify weekly differences in isokinetic measures. Tet-retest reliability was evaluated by ICC. No significant differences were found between weeks in any of the strength measures, and the reliability of the strength measures was considered excellent, except for concentric ankle dorsi-flexion. Although a significant difference was noted in weekly endurance measures of knee extension, the reliability of endurance measures by week was considered excellent for knee flexion and extension. Except for concentric ankle dorsi-flexion, the isokinetic strength and endurance measures are highly reliable when following the NASA ISS protocol. This protocol should allow accurate interpretation of isokinetic data even with a small number of crew members.
Keywords: HEF, iRED, BMD, horizontal exercise fixture, interim resistive exercise device, bone mineral density, countermeasures, muscle loss
Abstract: INTRODUCTION: Countermeasure exercises have been developed to reduce bone and muscle loss during space flight; however, until now no exercise device has been available to mimic vertical pelvis displacement in squat exercises with supine subjects during bed rest. A horizontal exercise fixture (HEF) was designed to be used with the interim Resistive Exercise Device (iRED) to mimic the biomechanical characteristics of a standing squat. The pelvic sled of the HEF is equipped with a counterweight that balances the pelvis in the vertical direction. PURPOSE: The purpose was to determine if iRED exercises could be performed on the HEF. Additionally, this evaluation sought to compute the appropriate counterweight for the pelvic sled exercises and to evaluate the electrical activity of the Vastus Lateralis Oblique (VLO). METHODS: Phase 1 used a 5th percentile female and a 95th percentile male to determine if the highest and lowest force levels were appropriate for a range of test subjects, and if a supine exercise could be performed with similar mechanics to the upright position. Phase II assessed the pelvis sled counterweights for various exercises, along with VLO activity. RESULTS: A number of exercises were performed on the HEF without any significant performance issues, and therefore could be performed in a bed rest study. Additionally, regression equations were developed to predict the ideal counterweight. CONCLUSION: A bed rest study using the HEF could be performed in which subjects execute a large number of the exercises that are similar to upright exercise.
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