Keywords: histories; documentation; records; simulator; simulation; thermal-vacuum; vacuum; rotation; temperature; mobility; lunar; environment; laboratory
Abstract: Few undertakings in the history of humanity can compare to the great technological achievement known as Project Apollo. Among those who witnessed Armstrong’s flickering television image were thousands of people who had directly contributed to this historic moment. Amongst those in this vast anonymous cadre were the personnel of the Space Environment Simulation Laboratory (SESL) at the Manned Spacecraft Center (MSC) in Houston, Texas. SESL houses two large thermal-vacuum chambers with solar simulation capabilities. At a time when NASA engineers had a limited understanding of the effects of extremes of space on hardware and crews, SESL was designed to literally create the conditions of space on Earth. With interior dimensions of 90 feet in height and a 55-foot diameter, Chamber A dwarfed the Apollo command/service module (CSM) it was constructed to test. The chamber’s vacuum pumping capacity of 1 x 10-6 torr can simulate an altitude greater than 130 miles above the Earth. A lunar plane capable of rotating a 150,000-pound test vehicle 180 deg replicates the revolution of a craft in space. To reproduce the temperature extremes of space, interior chamber walls cool to -280°F as two banks of carbon arc modules simulate the unfiltered solar light/heat of the Sun.With capabilities similar to that of Chamber A, early Chamber B tests included the Gemini modular maneuvering unit, Apollo EVA mobility unit and the lunar module. Since Gemini astronaut Charles Bassett first ventured into the chamber in 1966, Chamber B has assisted astronauts in testing hardware and preparing them for work in the harsh extremes of space.
Keywords: radiation, galactic cosmic rays, fluence, radiation absorption, radiation shielding, radiation transport
Abstract: space radiation transport models for shielding applications. The NASA space radiation transport model now predicts dose and dose equivalent in Earth and Mars orbit to an accuracy of +20%. However, larger error may occur in particle fluence predictions and there is interest in further assessments and improvements in NASA’s space radiation transport model. In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR) and the isotopic dependence of nuclear fragmentation cross-sections on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. Using NASA’s quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, we study the effect of the isotopic dependence of the primary GCR composition and secondary nuclei on shielding calculations. The QMSFRG is shown to accurately describe the iso-spin dependence of nuclear fragmentation. The principle finding of this study is that large errors (+100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid (~170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (<20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.
Keywords: decompression sickness, extravehicular activity, Hypobaric Decompression Sickness Databank, Cox proportional hazards model, censoring, frailty model, model validation
Abstract: In this paper we fit Cox proportional hazards models to a subset of data from the Hypobaric Decompression Sickness Databank. The data bank contains records on the time to decompression sickness (DCS) and venous gas emboli (VGE) for over 130,000 person-exposures to high altitude in chamber tests. The subset we use contains 1,321 records, with 87% censoring, and has the most recent experimental tests on DCS made available from Johnson Space Center. We build on previous analyses of this data set by considering more expanded models and more detailed model assessments specific to the Cox model. Our model, which is stratified on the quartiles of the final ambient pressure at altitude, includes the final ambient pressure at altitude as a nonlinear continuous predictor, the computed tissue partial pressure of nitrogen at altitude, and whether exercise was done at altitude. We conduct various assessments of our model, many of which are recently developed in the statistical literature, and conclude where the model needs improvement. We consider the addition of frailties to the stratified Cox model, but found that no significant gain was attained above a model that does not include frailties. Finally, we validate some of the models that we fit.
Keywords: Moon, Human Exploration, Lunar Science, Technology Demonstrations, Human Health and Performance, Candidate Sites, Timelines
Abstract: The goals and objectives of future lunar exploration are defined in terms of science, preparation for long-duration stays on the Moon, preparation for human exploration of Mars, exploring the possibility of economic uses of the Moon, and maintaining the health and performance of humans and machines on the Moon. These objectives can be met by carrying out a set of functional activities on the Moon such as scientific field investigations; sample collection and analysis; deployment of surface scientific instruments such as seismometers and telescopes; teleoperation of exploration and technology demonstration systems; intravehicular activity, maintenance and repair; and other activities. These are combined into a set of surface exploration mission options. Short-stay missions (e.g., 4 people for 4 days) that principally address scientific and technology verification are defined for three different types of sites, and long-stay missions (e.g., 4 people for 30 days), which can build up infrastructure for longer duration stays, are defined for two sites, including a south polar site. Representative timelines for crew surface activities are presented.This document is considered to be a snapshot that will be revised as the nature of human lunar missions become better understood.
Keywords: human factors engineering; spacecraft design; human performance; human tolerances; human behavior; aerospace engineering; long-duration spaceflight; human safety
Abstract: These guidelines and capabilities identify points of intersection between human spaceflight crews and mission considerations such as architecture, vehicle design, technologies, operations, and science requirements. In these pages we provide clear, top-level guidelines for human-related exploration studies and technology research that will address common questions and requirements. The human element is likely the most complex and difficult element of mission design because it significantly influences every aspect of mission planning - from basic parameters, such as duration, to more complex trade-offs including mass, volume, power, risk, and cost. Beyond a cause-and-effect statement, human-driven requirements are highly variable because of destination, operational environment, mission objectives, and more. Often a precise quantification of parameters for a human mission is difficult without further study or arriving at a precise definition of a specific mission architecture. Each mission design requires several iterations as the effects of the crew on the system architecture (and vice versa) coalesce. We thus see this document as a tool that mission designers can use to understand the many trade-offs inherent in planning a human spaceflight mission, with an emphasis on human safety, health, and performance.
Keywords: posture, human body, microgravity, physiological effects, gravitational physiology, human factors engineering
Abstract: Research has shown that the space environment induces physiological changes in the human body, such as fluid shifts in the upper body and chest cavity, spinal lengthening, muscular atrophy, space motion sickness, cardiopulmonary deconditioning, and bone mass loss, as well as some changes in visual perception. These require a period of adaptation and can substantially affect both crew member performance and posture. These physiological effects, when work activities are conducted, have been known to impact the body’s center of gravity, reach, flexibility, and dexterity. All these aspects of posture must be considered to safely and efficiently design space systems and hardware. NASA has documented its microgravity body posture in the Man-Systems Integration Standards (MSIS); the space community uses the MSIS posture to design workstations and tools for space application. However, the microgravity body posture should be further investigated for several reasons, including small sample size in previous studies, possible imprecision, and lack of detail. JSC undertook this study to investigate human body posture exhibited under microgravity conditions. STS-57 crew members were instructed to assume a relaxed posture that was not oriented to any work area or task. Crew members were asked to don shorts and tank tops and to be blindfolded while data were recorded. Video data were acquired once during the mission from each of the six crew members. No one crew member exhibited the typical NBP called out in the MSIS; one composite posture is not adequate. A range of postures may be more constructive for design purposes. Future evaluations should define precise posture requirements for workstation, glove box, maintenance, foot-restraint, and handhold activities.
Keywords: exercise physiology; human body; locomotion; physiological effects; treadmills; physical exercise; contingency
Abstract: The treadmill with vibration isolation system (TVIS) was developed to counteract cardiovascular, musculoskeletal, and neurovestibular deconditioning during long-duration missions to the ISS. However, recent hardware failures have necessitated the development of a short-term, temporary contingency exercise countermeasure for TVIS until nominal operations could be restored. The purpose of our evaluation was twofold: 1) to examine whether a slick-plate/contingency exercise surface (CES) could be used as a walking/running surface and could elicit a heart rate (HR) ³ 70% HR maximum and 2) to determine the optimal hardware configuration, in microgravity, to simulate running/walking in a 1-g environment. One subject participated in the slick surface evaluation and two subjects participated in the microgravity evaluation of the slick surface configuration. During the slick surface evaluation, the subject was suspended in a parachute harness and bungee cord configuration to offset the subject’s body weight. Using another bungee cord configuration, we added a vertical load back to the subject, who was then asked to run for 20 minutes on the slick surface. The microgravity evaluation simulated the ISS TVIS, and we evaluated two different slick surfaces for use as a CES. We evaluated each surface with the subject walking and running, with and without a handrail, and while wearing either socks or nylon booties over shoes. In the slick surface evaluation, the subject ran for 20 minutes and reached a maximum HR of 170 bpm. In the microgravity evaluation, the subjects chose the aluminum plate coated with Tufram as the CES, while wearing a pair of nylon booties over running shoes and using a handrail, as the optimal hardware configuration.
Keywords: orbital debris, meteoroids, hypervelocity impact, shielding, ISS, Shuttle, Orbiter, CONTOUR, impact protection, Hypervelocity Impact Technology Facility
Abstract: This report provides innovative, low-weight shielding solutions for spacecraft and the ballistic limit equations that define the shield's performance in the meteoroid/debris environment. Analyses and hypervelocity impact testing results are described that have been used in developing the shields and equations. Spacecraft shielding design and operational practices described in this report are used to provide effective spacecraft protection from meteoroid and debris impacts. Specific shield applications for the International Space Station (ISS), Space Shuttle Orbiter and the CONTOUR (Comet Nucleus Tour) space probe are provided. Whipple, Multi-Shock and Stuffed Whipple shield applications are described.
Keywords: decompression sickness, extravehicular activity, NASA Decompression Sickness Database, Prebreathe Reduction Protocol Database, spacesuit, venous gas emboli
Abstract: One hundred and three cases of hypobaric decompression sickness (DCS) are documented, with 6 classified as Type II DCS. The presence and grade of venous gas emboli (VGE) are part of the case descriptions. Cases were diagnosed from 731 exposures in 5 different altitude chambers from 4 different laboratories between the years 1982 and 1999. Research was funded by NASA to develop operational prebreathe (PB) procedures that would permit safe extravehicular activity from the Space Shuttle and International Space Station using an extravehicular mobility unit (spacesuit) operated at 4.3 psia. Both vehicles operate at 14.7 psia with an "air" atmosphere, so a PB procedure is required to reduce nitrogen partial pressure in the tissues to an acceptable level prior to depressurization to 4.3 psia. Thirty-two additional descriptions of symptoms that were not diagnosed as DCS together with VGE information are also included. The information for each case resides in logbooks from 32 different tests. Additional information is stored in the NASA Decompression Sickness Database and the Prebreathe Reduction Protocol Database, both maintained by the Environmental Physiology Laboratory at the Johnson Space Center. Both sources were reviewed to provide the narratives that follow.
Keywords: trauma; acute trauma; pulmonary; critical care; ISS; International Space Station
Abstract: The NASA critical path road map identifies “trauma and acute medical problems” as a clinical capability risk category. Specific risks include major trauma, organ laceration or contusion, hemoperitoneum, pulmonary failure, pneumo- and hemothorax, burn, open bone fracture, blunt head trauma, and penetrating injury. Risk mitigation includes capability for critical care monitoring. Currently, the ISS Crew Health Care System does not provide such capability. The Clinical Space Medicine Strategic Planning Forum (1997) identified developing trauma care capabilities as a top priority for space medicine. The Clinical Care Capability Development Project (CCCDP) subsequently undertook the task to address this need. In January 2000, JSC Medical Operations Branch was invited to participate in the RIMPAC 2000/Strong Angel exercise, which involved seven nations and several public health and disaster-response organizations, establishing a 300-person mock refugee camp to simulate mass dislocation due to conflict or natural disaster. A wireless network and satellite system connected the camp to the East Carolina University School of Medicine. One of Strong Angel’s objectives was to build a nomadic computing network matrix to link the 7 countries participating in this exercise through the ECU bridge. Medical Operations personnel used this exercise to evaluate critical care monitors in a real-world telemedicine setting analogous to ISS conditions and to simulate potential ISS medical scenarios. This exercise afforded a unique opportunity to work with commercial vendors and evaluate their leading-edge technology and evaluate the feasibility of treating an astronaut aboard ISS using limited medical resources. These opportunities were consistent with the CCCDP critical path toward enhancing long-term Advanced Life Support System capabilities.
Keywords: Time-varying electromagnetic field, rotating wall vessel, three-dimensional culture, neural tissue regeneration
Abstract: The present investigation details the development of model systems for growing two and three-dimensional human neural progenitor cells within a culture medium facilitated by a time-varying electromagnetic field (TVEMF). The cells and culture medium are contained within a two or three-dimensional culture vessel, and the electromagnetic field is emitted from an electrode or coil. These studies further provide methods to promote neural tissue regeneration by means of culturing the neural cells in either configuration. Grown in two-dimensions, neuronal cells extended longitudinally forming tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time-varying electrical current was conducted. In the three-dimensional aspect exposure to TVEMF resulted in the development of three-dimensional aggregates, which emulated organized neural tissues. In both experimental configurations, the proliferation rate of the TVEMF cells was 2.5 to 4.0 times the rate of the non-waveform cells. Each of the experimental embodiments resulted in similar molecular genetic changes regarding the growth potential of the tissues as measured by gene chip analyses, which measured more than 10,000 human genes simultaneously
Keywords: ultrasound; video data; video equipment; video tape recorders; echocardiography; sonography; Doppler; field rate; MPEG; resolution; radiology; analog; digital
Abstract: Most medical equipment on the International Space Station (ISS) is manifested as part of the U.S. or the Russian medical hardware systems. However, certain medical hardware is also available as part of the Human Research Facility. The HRF and the JSC Medical Operations Branch established a Memorandum of Agreement for joint use of certain medical hardware, including the HRF ultrasound system, the only diagnostic imaging device currently manifested to fly on ISS. The outcome of a medical contingency may be changed drastically, or an unnecessary evacuation may be prevented, if clinical decisions are supported by timely and objective diagnostic information. In many higher-probability medical scenarios, diagnostic ultrasound is a first-choice modality or provides significant diagnostic information. Accordingly, the Clinical Care Capability Development Project is evaluating the HRF ultrasound system for its utility in relevant clinical situations on board ISS. For effective management of these ultrasound-supported ISS medical scenarios, the resulting data should be available for viewing and interpretation on the ground, and bidirectional voice communication should be readily available to allow ground experts (sonographers, physicians) to provide guidance to the Crew Medical Officer. It may also be vitally important to have the capability of real-time guidance via video uplink to the CMO-operator during an exam to facilitate the diagnosis in a timely fashion. In this document, we strove to verify that the HRF ultrasound video output is compatible with the ISS video system, identify ISS video system field rates and resolutions that are acceptable for varying clinical scenarios, and evaluate the HRF ultrasound video with a commercial, off-the-shelf video converter, and compare it with the ISS video system.
Keywords: hydrogen, combustion, flammability, detonation, fire, slush, hazards, hydrogen embrittlement, hazards analysis
Abstract: The physical and combustion properties of hydrogen give rise to hazards that one must consider when designing and operating a hydrogen system. One of the major concerns is fire or detonation because of hydrogen’s wide flammability range, low ignition energy, and flame speed. Other concerns include contact and interaction with materials, such as the hydrogen embrittlement of materials and the formation of hydrogen hydrides. The low temperature of liquid and slush hydrogen bring other concerns related to material compatibility and pressure control; this is especially important when dissimilar, adjoining materials are involved. The potential hazards arising from these properties and design features necessitate a proper hydrogen hazards analysis before introducing a material, component, or system into hydrogen service. The objective of this guide is to describe the NASA Johnson Space Center White Sands Test Facility hydrogen hazards analysis method one should perform before hydrogen is used in components and/or systems. The method is consistent with standard practices for analyzing hazards. It is recommended that this analysis be made before implementing a hydrogen component qualification procedure. A hydrogen hazards analysis is a useful tool for hydrogen-system designers, system and safety engineers, and facility managers. A hydrogen hazards analysis can identify problem areas before hydrogen is introduced into a system, preventing damage to hardware, delay or loss of mission or objective, and possible injury or loss of life. This guide is based on information from the NASA Safety Standard for Hydrogen and Hydrogen Systems (NSS 1740.16) and experience derived from the development of a similar protocol for oxygen system hazards analysis. It was previously published as TP-WSTF-937
Keywords: radiation, shielding, space suit, electrons, space radiation, anisotropy, radiation damage, radiation protection, albedo, EMU, low Earth orbit
Abstract: This publication describes recent investigations that evaluate radiation shielding characteristics of NASA’s and the Russian Space Agency’s space suits. The Introduction describes the suits and presents goals of several experiments performed with them. The first chapter provides background information about the dynamic radiation environment experienced at ISS and summarizes radiation health and protection requirements for activities in low Earth orbit. Supporting studies report the development and application of a computer model of the EMU space suit and the difficulty of shielding EVA crewmembers from high-energy reentrant electrons, a previously unevaluated component of the space radiation environment. Chapters 2 through 6 describe experiments that evaluate the space suits' radiation shielding characteristics. Chapter 7 describes a study of the potential radiological health impact on EVA crewmembers of two virtually unexamined environmental sources of high-energy electrons - reentrant trapped electrons and atmospheric albedo or “splash” electrons. The radiological consequences of those sources have not been evaluated previously and, under closer scrutiny. A detailed computational model of the shielding distribution provided by components of the NASA astronauts’ EMU is being developed for exposure evaluation studies. The model is introduced in Chapters 8 and 9 and used in Chapter 10 to investigate how trapped particle anisotropy impacts female organ doses during EVA. Chapter 11 presents a review of issues related to estimating skin cancer risk from space radiation. The final chapter contains conclusions about the protective qualities of the suit brought to light from these studies, as well as recommendations for future operational radiation protection investigations and practices. The recent programmatic focus on radiation protection for EVA exposures is only one component of the NASA Space Radiation Health Project Office’s proactive management of radiation protection for human activities in space. Ionizing radiation exposures to long-term ISS crewmembers are increased by a factor of ~10 or more above typical Space Shuttle experiences, and it is quite possible that some individuals will receive doses that will restrict their time allowed on EVA or on orbit. Anticipation of these events prompted programmatic reviews and development of improved technologies and new procedures for the radiation mission support team, including near-real-time space weather monitoring, information analysis, integration, and reporting to flight surgeons and mission controllers. New research and dosimetry technologies and skills acquired by the NASA Space Radiation Health Project Office and its supporting research programs include improved spacecraft environmental and personnel dosimetry, improved ground-based physics and radiation transport models, leading-edge radiobiology studies of the deleterious effects of space-like ionizing radiation fields, and broadening and deepening investigations of risk analysis.
Keywords: injury; extravehicular activity; EVA; International Space Station; NBL; Neutral Buoyancy Lab; inverted body position; training; shoulder injury; musculoskeletal
Abstract: The number and complexity of extravehicular activities required for the completion and maintenance of the International Space Station is unprecedented. It is not surprising that training to perform these space walks presents a risk of overuse musculoskeletal injuries. The goal of this tiger team, created in December 2002, was to identify the different factors contributing to the risk of EVA training-related shoulder injury in the Neutral Buoyancy Lab at the Sonny Carter Training Facility and to make recommendations that would either significantly reduce or eliminate those risks. Since 1999, concerns have been expressed about the risk of shoulder injury associated with EVA training at the NBL, particularly in inverted body positions (McMonigal, 1999). A survey was developed and administered to 42 astronauts and astronaut candidates; the results suggest a causal relationship between EVA training at the NBL and the observed injuries. Also, during the tiger team review, it became evident that training in the extravehicular mobility unit may also result in other types of injuries, including fingernail delamination, elbow pain, knee pain, foot pain, and nerve compression leading to transient loss of sensation in certain areas of the upper or lower extremity. A multi-directorate team to detect, evaluate and respond to the medical issues associated with EVA training should be implemented immediately and given the appropriate resources and authority to reduce the risk of injury to crew during training to a level as low as reasonably achievable.
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