Keywords: aerospace environments; extravehicular activity; weightlessness; aerospace environments; Mars environment; lunar environment; space suits
Abstract: Our understanding of suited human performance in reduced-gravity environments includes observations from Apollo lunar surface extravehicular activities (EVAs) and studies in partial-gravity simulation environments. In developing design requirements for the next-generation lunar EVA suit, we initiated a series of tests to understand human performance and suit kinematics under simulated lunar EVA conditions. Study results will provide evidence-based recommendations for suit weight, mass, center of gravity (CG), pressure, and suit kinematic constraints. The EVA Walkback Test (EWT) used the Partial Gravity Simulator (POGO) in the Space Vehicle Mock-up Facility and the Mark III (MKIII) spacesuit. The MKIII provided dynamic ranges of motion for many planetary tasks. Results from EWT showed initial estimates for total metabolic cost of suited locomotion in the reduced-gravity lunar (1/6-g) and martian (3/8-g) environments and preliminary biomechanical parameters. For Integrated Suit Test-1 (IST-1), suited conditions had a constant CG location and suit mass while suit offload, pressure, and suit kinematic constraints varied. For unsuited conditions, the subject's mass was held constant while offload was varied or the subject's weight was held constant while the subject's mass was varied. This final report presents key findings of IST-1 as related to suited/unsuited human performance of treadmill locomotion on POGO.
Keywords: crew procedures (inflight); flight operations; lfie sciences; human factors engineering; human engineering; habitability; environmental monitoring; extravehicular activity
Abstract: This handbook provides guidance for crew health, habitability, environment, and human factors design of all NASA human space flight programs and projects. The two primary uses for the handbook are to help (1) requirement writers prepare contractual program-specific human interface requirements -- users include program managers and system requirement writers; and (2) designers develop designs and oeprations for human interfaces in spacecraft -- users include human factors practitioners, engineers and designers, crews and mission/flight controllers, and training and operations developers. The handbook is a resource document for NASA Space Flight Human Systems Standard (SFHSS), NASA-STD-3001 -- a two-volume set of NASA agency-level standards, established by the Office of the Chief Health and Medical Officer, that defines levels of acceptable risks to crew health and performance resulting from space flight. The handbook is a resource for implementing requirements in the SFHSS, providing the data and guidance necessary to derive and implement program-specific requirements compliant with SFHSS. The handbook addresses all crew operations inside and outside the spacecraft in space and on lunar and planetary surfaces, including design guidelines for crew interface with workstations, architecture, habitation facilities, and extravehicular activity systems; information describing crew capabilities and limitations (both physical and cognitive); and environmental support parameters.
Abstract: Contact the Mission Operations Directorate at the Johnson Space Center for information on this document or a copy of it.
Keywords: atmospheric entry; automatic flight control; automatic landing control; automatic pilots; fly by wire control; space shuttle orbiters; spacecraft control; spacecraft reentry; terminal area energy management
Abstract: The history of the development, verification, and flight testing of the Space Shuttle Orbiter entry flight control system (FCS)--also known as the entry digital autopilot (DAP)--is summarized. This report presents basic programmatic requirements and an overview of the evolutionary process from the mid-1970s through November 2009, including the entry FCS recerification after the STS-107 Columbia tragedy. Flight and ground test programs are summarized, with correlation between prediced results and flight data discussed where posible. An attempt is made to capture the thinking of engineers who designed the system and the logic used to make some of the critical design decisions. The document is not meant to give detailed data on operation of the control system, but to provide a general understanding of system history and of the effects that other systems (eg, guidance, navigation, aerodynamics, structures, and propulsion) have had on the development of the entry FCS.
Keywords: heart rate; sensors, bioinstrumentation; extravehicular activity; electrocardiography; space suits
Abstract: This paper presents results of preliminary engineering evaluations of various heart rate (HR) sensors and recommends technologies for further evaluation by the extravehicular activity (EVA) suit contractor. It focuses on sensor type, location, and implementation, allowing quick and easy don/doff while providing the best chance for meeting HR performance requirements. Included are lessons learned from previous market studies and testing at the National Center for Human Performance, Ames Research Center, Johnson Space Center, and Glenn Research Center, and during Small Business Innovation Research studies. While many studies were originally performed on electrocardiogram systems, many applicable lessons can be taken for HR sensor performance -- assuming the more accurate the R-wave captured, the more accurate the HR calculation. Although this paper addresses sensor selection, it is important to note that overall performance is tied to the entire system’s configuration. Artifact rejection and return of signal quality after motion artifact depends on interaction of the signal conditioning/pulse detection circuitry and the electrodes themselves. Cables and connectors can be a considerable source of noise. Many commercial off-the-shelf systems mentioned in this paper have proprietary systems for noise and motion artifact reduction; this too will need to be considered by the EVA suit contractor.
Keywords: environmental control; spacecraft guidance; spacecraft configurations; posture, human body; crew procedures (inflight); seats; reentry effects; seat belts
Abstract: During the June 2009 Orion landing and recovery subsystem design review, it was noted that the human system and various vehicle systems (eg, the Environmental Control and Life Support System and Guidance, Navigation, and Control System) are negatively affected by Orion assuming a stable 2 (upside down) configuration post landing. The stable 2 configuration, which is predicted to occur about 50% of the time, will be countered by an active up-righting system. Post-landing balloons will deploy and inflate, causing the vehicle to assume or maintain the stable 1 (up-right) configuration. During the design review, it was proposed that the up-righting system could be capable of righting the vehicle within 60 sec. However, this time limit posed a series of constraints on the design that made it less robust than desired. This report focuses on assessing the human system in the posture assumed when Orion is in the stable 2 configuration. Stable 2 will place suited, seated, and restrained crew members in a prone, head-up position for a period of time dependent on the functionality of the up-righting systems, ability of crew members to release themselves from the seat and restraints, and/or time to arrival of rescue forces.
Keywords: optic disc edema, intraocular hypertension, choroidal folds, venous congestion, long- duration, ocular testing
Abstract: The Space Medicine Division at NASA Johnson Space Center is charged with maintaining the health of the astronaut corps during all phases of training, space flight, and rehabilitation. Additionally, it has an ongoing interest in understanding the effects of long-duration space flight on the crew in preparation for exploration missions. Health maintenance for space flight is re-examined periodically, and when new information becomes available from flight experience and ground studies. In accordance with this philosophy and due to recent documented changes in visual acuity in association with physical findings in crewmembers (e.g., optic disc edema, choroidal folds, and cotton wool spots) following long-duration space flight, the Advanced Projects Section of Wyle Integrated Science & Engineering organized a 2-day summit to examine the new data. The summit brought together experts in ophthalmology and related fields and sought to elicit evidence-based expert opinion on screening, diagnosis, and treatment options, identify gaps in knowledge and medical capability, and propose relevant research initiatives.
Keywords: Medical Condition List, SMEMCL, ExMC, mission profile, HRP
Abstract: The Human Research Program (HRP) has assigned the Exploration Medical Capabilities (ExMC) element the responsibility of addressing the overarching risk of “the inability to adequately treat an ill or injured crewmember.” The Space Medicine Exploration Medical Condition List (SMEMCL) was created in order to define the set of medical conditions that are most likely to occur during any one of seven distinct mission profiles, as the first step in addressing the above mentioned risk. The list was derived from the International Space Station (ISS) medical checklist, the Space Shuttle (STS) medical checklist, Longitudinal Study of Astronaut Health (LSAH) in-flight occurrence data, and the Delphi study, and assumes use of the new Crew Exploration Vehicle (CEV). The list of conditions was further prioritized for the seven specific missions with the assistance of the ExMC Advisory Group, which included flight surgeons and representatives from the astronaut office, Space Medicine Division management, and the National Space Biomedical Research Institute.
Keywords: ARRBOD, Radiation, Acute Radiation Risk, BRYNTRN, SUMDOSE, organ dose, SPE
Abstract: The space radiation environment, particularly solar particle events (SPEs), poses the risk of acute radiation sickness (ARS) to humans; and organ doses from SPE exposure may reach critical levels during EVAs or within lightly shielded spacecraft. NASA has developed an organ dose projection model using the BRYNTRN with SUMDOSE computer algorithms, and a probabilistic model of Acute Radiation Risk (ARR). The risk projection models of organ doses and ARR take the output from BRYNTRN as an input to their calculations, but BRYNTRN requires extensive input preparation. With a graphical user interface (GUI) to handle input and output for BRYNTRN, the response models can be connected easily and correctly to BRYNTRN in a user-friendly way. A GUI for the Acute Radiation Risk and BRYNTRN Organ Dose (ARRBOD) projection code provides seamless integration of input and output manipulations, which are required for operations of the ARRBOD modules. The ARRBOD GUI is intended for mission planners, radiation shield designers, space operations in the mission operations directorate (MOD), and space biophysics researchers. The ARRBOD GUI will serve as a proof-of-concept example for future integration of other human space applications risk projection models. This version of the ARRBOD GUI is a new self-contained product and will have follow-on versions The major components of the overall system, the subsystem interconnections, and external interfaces are described in this report; and the ARRBOD GUI product is explained step by step in order to serve as a tutorial.
Keywords: oxygen production; electrolysis, water splitting; heat radiators; compressors, coolers; heat exchangers
Abstract: Concepts for liquefying oxygen generated from water electrolysis subsystems on the lunar surface were explored. Concepts for oxygen liquefaction units capable of generating 1.38 lb/hr (0.63 kg/hr) liquid oxygen were developed. Heat and mass balance calculations for the liquefaction concepts were conducted. Stream properties, duties of radiators, heat exchangers, and compressors for the selected concepts were calculated and compared.
Keywords: carbon dioxide, operational exposure, ppCO2, dyspnea
Abstract: The effects of ambient carbon dioxide and exposure limits have been well studied on Earth. However, informal crew reports on the International Space Station have suggested that astronauts are developing CO2-related symptoms such as headache and lethargy at lower than expected CO2 levels and that symptoms tend to resolve when CO2 level is decreased. In-flight data to date support an association between elevated ppCO2 and CO2-related symptoms, but more research is needed to conclude causality. What appears to be increased CO2 sensitivity in microgravity may be attributable to individual predisposition to CO2 retention, adaptation to microgravity, and local fluctuations in CO2 that are not measured by fixed sensors. A review of the current occupational exposure limits supports lowering of the permissible exposure limit for the ISS and beyond, although evidence-based limits for space flight have yet to be defined.
Keywords: decompression sickness, DCS, hypobaric, patent foramen ovale, PFO
Abstract: Astronauts are at risk for developing decompression sickness (DCS) while exposed to the hypobaric environment of the extravehicular suit in space, in terrestrial hypobaric chambers, and during ascent from neutral buoyancy training dives. There is increasing recognition that DCS risk is different between diving and altitude exposures, with many individual parameters and environmental factors implicated as risk factors for development of DCS in divers but are not recognized as risk factors in altitude exposures. Much of the literature to date has focused on patent foramen ovale (PFO), which has long been considered a major risk factor for DCS in diving exposures, but its link to serious DCS in altitude exposures remains unclear. Knowledge of those risk factors specific to hypobaric DCS may help identify susceptible individuals and aid in astronaut selection, crew assignment, and mission planning. This paper reviews the current literature pertaining to these risk factors, including PFO, anthropometric parameters, gender, menstrual cycle, lifetime diving experience, physical fitness, biochemical levels, complement activation, cigarette smoking, fluid balance, and ambient temperature. Further research to evaluate pertinent risk factors for DCS in altitude exposures is recommended.
Keywords: arrhythmia, lone atrial fibrillation
Abstract: To evaluate current standards and practices related to atrial arrhythmias in astronauts, Space Medicine’s Advanced Projects Section was tasked with organizing a 1-day summit to discuss Space Medicine’s approach to atrial arrhythmias in the astronaut cohort. Since 1959, 11 cases of atrial fibrillation, atrial flutter, or supraventricular tachycardia have been recorded among active corps crewmembers. Six additional cases have been identified among retired astronauts. Most of the cases were paroxysmal (intermittent), although a few were sustained. While most of the affected crewmembers were asymptomatic, those slated for long-duration space flight underwent radiofrequency ablation treatment to prevent further episodes of the arrhythmia. The summit was thus convened to solicit expert opinion on screening, diagnosis, and treatment options, to identify gaps in knowledge, and to propose relevant research initiatives.
Keywords: functional mobility testing, suited subjects, Constellation Suit Element, EVA
Abstract: A novel approach was used in this test for the creation of mobility requirements to be fed into the Human-Systems Integration Requirements and Engineering Requirements Documents. Existing suits may not provide adequate mobility to perform all functional tasks required in future missions. Looking solely at maximum unsuited mobility could be unrealistic and unnecessary to design into a suit. The new approach focused instead on functional range of motion. Setting design requirements based on the mobility necessary to perform a broad spectrum of functional tasks should save resources while still providing a suit capable of performing all tasks that a suited crewmember is likely to encounter. Unsuited functional mobility testing revealed some interesting nuances of human movement including variances in mobility utilized when completing functional tasks as well as the impact of compound joint motions and the influence of joint loading on range of motion. Suited requirements must reflect the fact that altered movement strategies are utilized while wearing a space suit. Improved methods for the creation of space suit design requirements should lead to improved suit performance while maintaining crewmember safety and reducing overall costs.
Keywords: aerospace environments; extravehicular activity; weightlessness; aerospace environments; Mars environment; lunar environment; space suits
Abstract: Observations from Apollo lunar surface extravehicular activities (EVAs) and a few studies conducted in partial-gravity simulation environments have helped us understand suited human performance in reduced-gravity environments. The Constellation Program EVA Systems Project Office initiated a series of tests aimed at increasing our understanding of human performance and suit kinematics under various simulated lunar EVA conditions, including matched unsuited controls, to identify the specific metabolic costs and biomechanics of the prototype Mark III Advanced Spacesuit Technology Demonstrator. A primary goal of the series is to provide evidence-based recommendations for suit mass, center of gravity, pressure, and suit kinematic constraints that optimize human performance in partial-gravity environments. Results will be combined with studies in other lunar analogs to evaluate the effectiveness and limitations of these environment. As our understanding of suited human performance matures, different combinations of variables can be evaluated to determined whether significant interactions exist between parameters. This report provides an overview of key findings of Integrated Suit Test (IST)-2. As future tests are completed, focusing on other suit factors, analog environments, or different suits, study results will be combined and reevaluated. The series of tests comprising IST-2 was conducted from June 13, 2007 through October 24, 2007.
Keywords: center of gravity; human performance; metabolism; gravitational fields; lunar gravitation; environment simulation; stability tests; posture, human body
Abstract: This test evaluated the effects of varying center-of-gravity (CG) locations on unsuited (ie, shirtsleeve) human performance. Although different performance results were noted, data analysis indicates many of these performance differences may have resulted from system dynamics, hardware setup, and/or testing methodology. Three of the configurations unexpectedly had almost identical metabolic values. This lack of variability indicates that either there were no notable differences in human performance among them or other factors may have compromised our ability to effectively vary CG using an overhead suspension lunar gravity simulator. Metabolic and subjective results among CG conditions for ambulation were very similar, leading to the same conclusions. Although the Space Vehicle Mockup Facility’s partial-gravity simulator "POGO" provided a reasonable ground-based analog for testing postural stability during reduced-gravity loading, mechanical couplings limit observations to a single plane of motion (sagittal), and its upward force vector may have a mechanical and/or physiologic (haptic) stabilizing influence on balance control that could reduce apparent instabilities. Postural stability appeared to be degraded during the simulated reduced-gravity loading conditions tested in this experiment. We therefore recommend that follow-up experiments be performed, probably during parabolic flight, to verify these findings without the potential mechanical-based confounding factors of the POGO system
Keywords: human behavior; human factors engineering, manned space flight; man environment interactions; morale, psychology; human performance, adjustment
Abstract: Personal journals maintained by NASA astronauts during 6-month expeditions on board the International Space Station (ISS) were analyzed to obtain information concerning a wide range of behavioral and human factors issues. Astronauts wrote most about their work, followed by outside communications (with Mission Control, family, and friends), adjustment to the conditions, interactions with crew mates, recreation/leisure, equipment (installation, maintenance), events (launches, docking, hurricanes, etc.), organization/management, sleep, and food. The study found evidence of a decline in morale during the third quarters of the missions, and identified key factors that contribute to sustained adjustment and optimal performance during long-duration space expeditions. Astronauts reported that they benefited personally from writing in their journals because it helped them maintain perspective on their work and relations with others. Responses to questions asked before, during, and after the expeditions show that living and working on board the ISS is not as difficult as the astronauts anticipate before starting their 6-month tours of duty. Recommendations include application of study results and continuation of the experiment to obtain additional data as crew size increases and operations evolve.
Keywords: space debris; geosynchronous orbits; Earth orbital environments; brightness; inclination, orbits; targets; range, orbital position estimation; astronomical telescopes
Abstract: Orbital debris is a concern to all nations that use satellites or launch space vehicles. The debris field scattered near Earth's geosynchronous orbit (GEO) poses a threat to anything residing in or passing through it. To mitigate risk and minimize the environment's expansion, the environment must be understood. NASA uses the Michigan Orbital DEbris Survey Telescope (MODEST), a University of Michigan-owned 0.61-m aperture Schmidt telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile, to help characterize the debris environment in GEO. The objectives for this survey are to determine the extent and character of debris in GEO, specifically by obtaining distributions for the brightness, inclination (INC), right ascension of ascending node (RAAN), and mean motion for the debris. This report describes the collection and analysis of 35 nights of data in contract year (CY) 2002 and 16 nights in CY 2003. Twenty-three objects on average were detected nightly for both years: in CY 2002, 76% were correlated targets (CTs) and 24% were uncorrelated targets (UCTs); in CY 2003, 66% were CTs and 34% were UCTs. Estimates can be made from correlated objects on errors associated with derived quantities of range, INC, and RAAN.
Keywords: human factors engineering; human resources; commercial spacecraft; space commercialization; assurance; redundancy; reliability
Abstract: The U.S., Russian, and China have each addressed the question of human-rating spacecraft. NASA's operational experience with human-rating primarily resides with Mercury, Gemini, Apollo, Space Shuttle, and International Space Station. NASA's latest developmental experience includes Constellation, X38, X33, and the Orbital Space Plane. If domestic commercial crew vehicles are used to transport astronauts to and from space, Soyuz is another example of methods that could be used to human-rate a spacecraft and to work with commercial spacecraft providers. For Soyuz, NASA's normal assurance practices were adapted. Building on NASA's Soyuz experience, this report contends all past, present, and future vehicles rely on a range of methods and techniques for human-rating assurance, the components of which include: requirements, conceptual development, prototype evaluations, configuration management, formal development reviews (safety, design, operations), component/system ground-testing, integrated flight tests, independent assessments, and launch readiness reviews. When constraints (cost, schedule, international) limit the depth/breadth of one or more preferred assurance means, ways are found to bolster the remaining areas. This report provides information exemplifying the above safety assurance model for consideration with commercial or foreign-government-designed spacecraft. Topics addressed include: U.S./Soviet-Russian government/agency agreements and engineeriung/safety assessments performed with lessons learned in historic U.S./Russian joint space ventures.
Keywords: space debris; geosynchronous orbits; Earth orbital environments; brightness; inclination, orbits; targets; range, orbital position estimation; astronomical telescopes
Abstract: Orbital debris is a concern to nations using satellites or launch space vehicles. The debris field scattered near Earth's geosynchronous orbit (GEO) poses a threat to anything residing in or passing through it. To mitigate risk and minimize this environment's expansion, the environment must be understood. NASA uses the Michigan Orbital DEbris Survey Telescope (MODEST), a Univesity of Michigan-owned 0.61-m aperture Schmidt telescope at Cerro Tololo Inter-American Observatory in Chile, to help characterize the GEO debris environment. Objectives for this survey are to determine the extent and character of debris in GEO, specifically by obtaining distributions for brightness, inclination (INC), right ascension of ascending node (RAAN), and mean motion for the debris. This report describes the collection and analysis of 42 nights of data in contract year (CY) 2004, 23 nights in CY 2005, and 35 nights in CY 2006. Eighteen objects on average were detected nightly: in CY 2004, 72% were correlated targets (CTs) and 27% were uncorrelated targets (UCTs); in CY 2005, 74% were CTs and 26% were UCTs; and in CY 2006, 76% were CTs and 24% were UCTs. Estimates can be made from correlated objects on errors associated with derived quantities of range, INC, and RAAN.
Keywords: hatches; air locks; manned space flight; Mercury project; Gemini project; Apollo project; Apollo Soyuz test project; Soyuz spacecraft; Space Shuttle orbiters
Abstract: The Johnson Space Center (JSC) Flight Safety Office has developed this compilation of historical information on spacecraft crew hatches to assist the Safety Technical Authority in the evaluation and analysis of worldwide spacecraft crew hatch designs and performance. Among the programs addressed are: the United States Mercury, Gemini, Apollo, Skylab, Apollo-Soyuz (a joint US-USSR project), and Space Shuttle Orbiter; the Russian Vostok, Voskhod, Soyuz, Progress, Almaz, Salyut, Mir, and Buran; and the Chinese Shenzhou. The observations and findings are presented first by country and then organized within each country section by program in chronological order of emergence. A host of reference sources used to augment the personal observations and comments of the author are listed in the reference section of this document. Careful attention to the selection and inclusion of photographs, drawings, and diagrams is used to give visual asociation and clarity to the topic areas examined. Because of the scope of this report, recommendations and conclusions are not offered.
Keywords: investigation; simulation; radiation transport; radiation dosage; radiation shielding; radiation spectra; particle interactions
Abstract: In this paper, we report the results of modeling and simulation studies in which the radiation transport code FLUKA (FLUktuierende Kaskade) is used to determine the changes in total ionizing dose (TID) and single-event effect (SEE) environments behind aluminum, polyethylene, carbon, and titanium shielding masses when the assumed form (ie, Band or Exponential) of the solar particle event (SPE) kinetic energy spectra is changed. FLUKA simulations have fully three spatial dimensions with an isotropic particle flux incident on a concentric spherical shell shielding mass and detector structure. The effects are reported of both energetic primary protons penetrating the shield mass and secondary particle showers caused by energetic primary protons colliding with shielding mass nuclei. SPE heavy ion spectra are not addressed. Our results, in agreement with previous studies, show that use of the Exponential form of the event spectra can seriously underestimate spacecraft SPE TID and single-event environments in some, but not all, shielding mass cases.
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 2009 to June 2010. 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 the 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: cryogenic propellants, hypergolic, in situ fuel generation, reaction control system, RCS, Liquid Oxygen/Ethanol and Liquid Oxygen/Methane
Abstract: Since 2001, the National Aeronautics and Space Administration (NASA) has worked to develop spacecraft reaction control systems (RCSs) that use nontoxic and cryogenic propellant combinations, such as liquid oxygen (LO2) and ethanol and LO2 and liquid methane (LCH4), as alternatives to common systems that rely on the highly toxic and more expensive hypergolic fuels. Compared with these propellants, cryogenics offer higher performance, easier ground handling, and can be generated in situ on the Moon or Mars. System studies have shown performance benefits for an integrated main engine and RCS that reduces mass and simplifies the system. However, advanced technology is required to store cryogenic propellants in liquid form and feed them to a pulsing RCS engine. Testing began with the firing of three 870-lbf (3870-N) thrust engines on a LO2/ethanol feed system; the engines were later modified and fired on a LO2/LCH4 feed system across a matrix of propellant inlet temperatures and pressures, engine duty cycles, and pulse times. 1,685 firings using LO2/ethanol propellants and 733 firings using LO2/LCH4 propellants were completed. The impulse bit pulse-to-pulse repeatability of both the LO2/ethanol and LO2/LCH4 thrusters was typically within 5%. Several problems related to igniter ignition reliability were uncovered and resolved, and it was determined that more oxygen in the main chamber was required for reliable main-stage ignition. The hardware proved durable given the number of off-nominal engine firings, and the cryogenic feed system and Thermodynamic Vent System (TVS) were able to maintain propellant temperatures within tight tolerances. Overall, LCH4 is a better match with LO2 than ethanol because of its lower freezing point and higher vapor pressure.
Keywords: cabin atmospheres; controlled atmospheres; life support systems; decompression sickness; hypoxia; fire resistance; habitats; Constellation Program
Abstract: The authors of this document recommend that, to enable missions to the moon and Mars, NASA's Constellation vehicles, habitats, and spacesuits employ an integrated set of internal atmospheres rather than a single design for all elements. These atmospheres must mitigate the risks of fire, decompression sickness, and hypoxia while enabling crew excursions on planetary surfaces. It should be noted that the recommendations provided in this document are not requirements; instead, they reflect technical considerations only. To support the recommendations made herein, Constellation should institute a modified standard NASA flammability test as soon as possible to generate ignition threshold data for key spacecraft materials. This modified test will allow the agency to identify materials at risk from increases in oxygen concentration, minimize potential impacts, and allow for development of sound requirements for landers and habitats. The Human Research, Technology Development, and Constellation Programs should also initiate activities to enable atmosphere designs for, respectively, human research, technology development, and program-specific studies to validate these recommendations for the Constellation habitable elements.
Keywords: DRATS, SPR, LER, rover, lunar, traverse, Black Point Lava Flow,
Abstract: A system of two or more Small Pressurized Rovers (SPRs), also referred to as Lunar Electric Rovers (LERs), is an integral part of NASA’s plans for returning humans to the moon. In the SPR concept, each vehicle includes a small pressurized cabin to safely sustain two crewmembers on the surface for 14 to 28 days. Through suit ports, crewmembers may rapidly egress and ingress the cabin for EVAs. In addition to achieving a surface exploration range that is potentially orders of magnitude greater than what was achievable during the Apollo Program, the SPR concept offers many other benefits, particularly with respect to the health, safety, and productivity of crewmembers. The primary purpose of the DRATS 2008 field test, at Black Point Lava Flow in Arizona, was to objectively and quantitatively compare the scientific productivity and human factors during 1-day exploration, mapping, and geological traverses performed using SPR and Unpressurized Rover (UPR) prototype vehicles. The habitability, human factors, and performance characteristics of the SPR vehicle and crew were also recorded throughout a high-fidelity 3-day lunar traverse simulation. Quantitative assessment of crew productivity by on-site expert field geologists found that compared with UPR traverses, the same crewmembers were 57% more productive during SPR traverses and used 61% less EVA time. The habitability and human factors of the SPR throughout the 3-day traverses was acceptable, although suggested modifications to several vehicle subsystems were identified in the assessment.
Keywords: environment simulation; gravitational physiology; artificial gravity; gravitational effects; environment effects; human factors engineering; space suits
Abstract: Simulating partial gravity on Earth is difficult. Many methods exist; all have significant limitations. This report focuses on: characterizing the partial-gravity analog environments used during integrated suit tests conducted between 2006 and 2009; how subjects performed in the two testing environments; how the test environments compared with each other; how strengths and weaknesses associated with each environment affected the quality of partial-gravity simulation for human performance testing; and general lessons learned on usability and features of each environment. The primary partial-gravity analog environments discussed are: the Space Vehicle Mockup Facility partial gravity simulator (POGO), which uses a vertically oriented, manually adjusted, servo-controlled pneumatic cylinder to create a selectable offload of a subject and allows for up to 2.4 m vertical travel; and the Reduced Gravity office C-9 parabolic-flight aircraft, which allows unrestrained movement in all 6 degrees-of-freedom and provides a true lunar-gravity kinetic environment with all aspects of subject and suit offloaded to the same partial-gravity level. We believe a ground-based, partial-gravity analog that has the advantages of POGO while improving on POGO's limitations offers the best primary test bed for characterizing suited human performance. Parabolic flight would then be used for specific tests and limited verification of ground-based simulators.
Keywords: EVA, SEV, exploration, rover, metabolic energy consumption
Abstract: The purpose of this report is to document preliminary, predicted, life sciences implications of expected operational concepts for lunar surface extravehicular activity (EVA). Algorithms developed through simulation and testing in lunar analog environments were used to predict crew metabolic rates and ground reaction forces experienced during lunar EVA. Subsequently, the total metabolic energy consumption, the daily bone load stimulus, total oxygen needed, and other variables were calculated and provided to Human Research Program and Exploration Systems Mission Directorate stakeholders. To provide context to the modeling, the report includes an overview of some scenarios that have been considered. Concise descriptions of the analog testing and development of the algorithms are also provided. This document may be updated to remain current with evolving lunar or other planetary surface operations, assumptions and concepts, and to provide additional data and analyses collected during the ongoing analog research program.
Keywords: parabolic flight, varying gravity on movement biomechanics
Abstract: his test was a continuation of the testing series, sponsored by the Constellation Program (CxP) EVA Systems Project Office (ESPO), that is being conducted to enable development of optimized design requirements for the next-generation lunar extravehicular activity (EVA) suit. The test series is a collaborative effort of the Crew and Thermal Systems Division (CTSD), the EVA Physiology, Systems, and Performance Project (EPSP), the Anthropometry and Biomechanics Facility (ABF), and the Usability Testing and Analysis Facility (UTAF). The investigators aim to understand human performance and suit kinematics under a variety of simulated lunar EVA conditions produced by a parabolic flight aircraft. The ways in which suit kinematics, weight, mass, center of gravity (CG), and pressure affect human performance during EVA-relevant tasks are being systematically evaluated. Investigators are developing a parametric understanding of the interrelationships between suit weight, mass, pressure, CG, and crew anthropometrics and performance, while defining the limitations and correction factors associated with each environment. This test was designed to provide data to compare with earlier human performance testing on the Space Vehicle Mockup Center’s Partial Gravity Simulator (POGO) and to provide guidance for the design of other reduced-gravity simulator projects such as ARGOS (Active Response Gravity Offload System). The test was also designed to conduct new research into the effects of varied CG and varied mass on suited human performance. The results will provide insights that may drive CxP requirement definitions and suit designs that are optimized for the anthropometric range of crewmembers and for the targeted operational environment.
Keywords: Knee extension, knee flexion, protocol repeatability
Abstract: The purpose of this protocol evaluation was to compare the repeatability of a discrete protocol with a continuous protocol for determining maximum muscular strength on the HUMAC NORM dynamometer. Eight subjects performed concentric knee extension and flexion at 60 degrees per second to test muscular strength. Each subject performed two different testing protocols twice with different operators. The protocols were 1) Continuous Protocol – the subject performed five repetitions of concentric knee extension and flexion continuously at a rate of 60 degrees per second in the same test trial – and 2) Discrete Protocol – the subject performed five repetitions of concentric knee extension, with brief periods of rest between repetitions, at a rate of 60 degrees per second in one test trial and then performed another trial of five repetitions to test concentric knee flexion. The comparison of the discrete and continuous protocols was inconclusive. The discrete protocol was slightly more repeatable during knee extension, with a percent difference of 7.28% compared to a percent difference of 9.70% for the continuous protocol. However, when subjects performed knee flexion, using the discrete protocol resulted in a percent difference of 3.78%, which indicated slightly lower repeatability than the 2.98% found with the continuous protocol. Therefore, no meaningful difference was found between the two protocols.
Keywords: system safety analysis, FMEA, hazard report, , STAT
Abstract: This is a progress report for work performed in 2009 concerning the development of automated tools for system safety analysis. This involves a suite of two application software packages, Semantic Text Analysis Tool (STAT) and the Hazard Identification Tool (HIT). STAT is used to extract key information from FMEAs and hazard reports, then HIT generated models integrate the information into a visualization or graphical display. These visualizations are helpful to safety engineers by revealing information that is redundant (e.g., multiple FMEAs on the same component), innaccurate or out of date.
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