Keywords: Spacecraft Performance, spacecraft rendezvous, spacecraft guidance
Abstract: Much can be learned from well-written descriptions of the technical and organizational factors that lead to an accident. Subsequent analysis by third parties of investigation reports and associated evidence collected during the investigations can lead to additional insight. Much can also be learned from documented close calls that do not result in loss of life or a spacecraft, such as the Mars Exploration Rover Spirit software anomaly, the SOHO mission interruption, and the NEAR burn anomaly. Seven space shuttle incidents fall into the latter category: Rendezvous Target Failure On STS-41B; Rendezvous Radar Anomaly and Trajectory Dispersion-STS-32 ;Rendezvous Lambert Targeting Anomaly-STS-49; Rendezvous Lambert Targeting Anomaly-STS-51; Zero Doppler Steering Maneuver Anomaly-STS-59; Excessive Propellant Consumption During Rendezvous-STS-69; Global Positioning System Receiver and Associated Shuttle Flight Software Anomalies-STS-91 Procedural work-arounds or software changes prevented them from threatening mission success. Extensive investigations, which included the independent recreation of the anomalies by multiple Shuttle Program organizations, were the key to determining the cause, accurately assessing risk, and identifying software and software process improvements. Lessons learned from these incidents not only validated long-standing operational best practices, but serve to promote discussion and mentoring among Program personnel and are applicable to future space flight programs.
Keywords: Solid propellant rocket engines,space shuttle boosters, space debris
Through an intensive collection and assimilation effort of SRM related data and resources, the author offers a resolution to the uncertainties surrounding SRM particulate generation, sufficiently so to enable a first-order incorporation of SRMs as a source term in space debris environment definition. The following five key conclusions are derived:
1) The emission of particles in the size regime of greatest concern from an orbital debris hazard perspective (D >100 µm), and in significant quantities, occurs only during the Tail-off phase of SRM burn activity.
2) The velocity of these emissions is correspondingly small - between 0 and 100 m/s.
3) The total Tail-off emitted mass is between approximately 0.04 and 0.65% of the initial propellant mass.
4) The majority of Tail-off emissions occur during the 30 second period that begins as the chamber pressure declines below approximately 34.5 kPa (5 psia).
5) The size distribution for the emitted particles ranges from 100 µm
Keywords: ignition, combustion, oxygen-enriched environment, oxygen hazards analysis
Abstract: Understanding and preventing fire hazards is necessary when designing, maintaining, and operating oxygen systems. Ignition risks can be minimized by controlling heat sources and using materials that will not ignite or will not support burning in the end-use environment. Because certain materials are more susceptible to ignition in oxygen-enriched environments, a compatibility assessment should be performed before the component is introduced into an oxygen system. This document provides an overview of oxygen fire hazards and procedures that are consistent with the latest versions of American Society for Testing and Materials (ASTM) Standards G63 (1999) and G94 (2005) to address fire hazards associated with oxygen systems. This document supersedes the previous edition, NASA Technical Memorandum 104823, Guide for Oxygen Hazards Analyses on Components and Systems (1996). The step-by-step oxygen compatibility assessment method described herein (see Section 4) enables oxygen-system designers, system engineers, and facility managers to determine areas of concern with respect to oxygen compatibility and, ultimately, prevent damage to a system or injury to personnel.
Keywords: Materials, fractures, tests, reaction control
Abstract: In April 2004, the Space Shuttle Orbiter Reaction Control System (RCS) thruster serial number (S/N) 120’s injector was found to be cracked while undergoing a nozzle retrofit at the White Sands Test Facility (WSTF). The RCS is composed of safety-critical propulsion hardware elements used to control the attitude of the space shuttle orbiter during virtually all operational mission phases. Since a failure resulting from an RCS thruster burn-through (initiated from a crack) could be catastrophic, an official flight constraint was issued until flight safety could be adequately demonstrated. One recommendation was to reproduce the cracking in the laboratory to understand fully the driving environments. The Johnson Space Center (JSC) Materials & Processes (M&P) Branch initiated an effort starting in January 2005 to reproduce the cracking in the niobium injector. The results were successful. The specific conditions necessary to cause cracking were explicitly established and bounded. Each of the following conditions is necessary in combination: 1. A mechanically disturbed/cold-worked free surface (plastic deformation from machining, handling, fastener installation, etc.) 2. An externally applied sustained tensile stress near yield strength 3. Presence of fluorine-containing fluids on exposed tensile/cold-worked free surfaces 4. Sustained exposure to temperatures greater than 400°F
Keywords: Human factors engineering, human factors laboratories
Abstract: This six-month gap analysis included literature reviews, database searches, interviews with NASA personnel, and then, a survey of NASA program and project managers as stakeholders. The primary focus of the GAP was on tools and methods to aid in the development of requirements and guidelines for the Crew Exploration Vehicle, since there was an immediate need for such information. However, the GAP is seen as a long-term effort and, therefore, future lunar and Mars exploration missions, as well as ground support needs for all missions, were also considered. The project was divided into four parts, two phases for data gathering, and two for compiling and prioritizing results. The Human Factors Background Review focused on the results of space program literature searches, review of human factors documents, and interviews of human factors personnel. The Field User Review focused on interviewing people outside the human factors area, but who work with crew interfaces. The results from these phases were then compiled and categorized into logical human factors topic areas. Using this compiled list, the Gap Evaluation phase began. In this phase the categories and description of potential research topics were rated by GAP personnel on seven different factors to create a reduced list to present to stakeholders. A more concise list of topic areas were then sent to NASA stakeholders to obtain their prioritization and buy-in of the important areas for human factors research. Last, the identified gaps were prioritized using four factors: CEV need, interview significance, stakeholder rating, and relevance to the Exploration Systems Architecture Study.
Keywords: Space debris, obstacle avoidance, Global Tracking Network, space surveillance, exclusion
Abstract: Both the “exclusion volume” and “maneuver threshold” methods have been carefully investigated by performing detailed calculations of debris risk over time and debris avoidance maneuver rate for the Space Transportation System Orbiter and the International Space Station. The underlying mathematics of the two methods is identical. Also, conjunction screening is based upon an exclusion volume; the efficiency of the screening exclusion volume is the limiting efficiency of the debris avoidance process, whether the threshold method or the exclusion box method is employed in the final decision process. This analysis shows the threshold method to have the advantages of somewhat better risk reduction and far fewer maneuvers. All computations are based on empirically determined covariance distributions for STS and the orbital debris population. The covariance of the ISS is assumed to be that of an orbital debris object, subject to the same atmospheric drag as the ISS. State vector covariances for STS were determined from recent tracking data for 2, 4, 8, and 12-hour propagation times for low, moderate, and high vehicle activity. These covariances were combined with the debris covariances, to determine the maneuver rate and fractional residual risk associated with different screening box shapes and sizes and different collision probability maneuver thresholds.
Keywords: Space debris, obstacle avoidance, Global Tracking Network, space surveillance, maneuvers
Abstract: The decision for the International Space Station to perform a maneuver to avoid orbital debris will be based upon a predicted collision probability. The collision probability will be calculated using real-time best estimates of the debris and ISS position state and position error covariance, propagated to the anticipated time of conjunction, or time of closest approach (TCA). If the computed collision probability exceeds a threshold value, the Red Threshold, a maneuver will be performed unless prevented by other operational considerations. The debris position and its uncertainty, propagated to TCA, will be supplied by United States Space Command, by processing observations from its Space Surveillance Network. Given the distribution of position errors for a space vehicle and the debris population, it is possible to calculate both the anticipated maneuver rate and the residual risk resulting from the choice of a maneuver threshold. The lower the probability threshold, the more maneuvers will be performed. However, no matter how many maneuvers are performed, risk can never be completely eliminated. Further, the performance of a debris avoidance maneuver disrupts the operation of the ISS micro-gravity laboratory and also complicates altitude management for ISS. Clearly the need is to achieve the maximum possible risk reduction while maintaining a sustainable maneuver rate.
Keywords: Sensorimotor performance, physiological tests, vestibular tests
Abstract: This short report provides a brief history of space flight, serves as a valuable resource for neurovestibular and sensorimotor space flight experiments conducted by all countries through 2005, and finally, it provides a comprehensive set of space flight physiology references with an emphasis on sensorimotor documents. Therefore, the intent and purpose of this historical overview of neuroscience and space flight is two-fold: First to equip researchers with a single, common reference document, and second, to allow those who helped create this history, a record of accomplishment.
Keywords: physical work; psychological factors; astronaut performance; space flight stress; emotional factors; human factors engineering; training analysis
Abstract: Long-duration space missions place on crewmembers unique physical, environmental, and psychological demands that directly affect their ability to live and work in space. A growing body of research on crews working for extended periods in isolated, confined environments reveals the existence of psychological and performance problems in varying degrees of magnitude. Research has also demonstrated that although the environment plays a cathartic role, many of the problems encountered are due to interpersonal frictions that affect individuals differently. Consequently, crewmembers often turn to maladaptive behaviors as coping mechanisms, resulting in decreased productivity and psychological discomfort. From this research, critical skills have been identified that can help a crewmember better navigate the psychological challenges of long-duration spaceflight. Although most people lack several of these skills, the majority can be learned, so a training program can be designed to teach crewmembers effective leadership, teamwork, and self-care strategies that will help minimize the emergence of maladaptive behaviors. The purpose of this report is to review the training literature to help determine the optimal instructional methods to use in delivering psychological skill training to the U.S. Astronaut Expedition Corps, and to detail the structure and content of the proposed Astronaut Expedition Corps Psychological Training Program.
Keywords: Space suits, protective clothing, Mars exploration
Abstract: The MarsSuit Project is an innovative research initiative that will engage multiple universities in a coordinated and synergistic effort to assist NASA in the formidable task of designing a lightweight, blue-collar Mars Extravehicular Mobility Unit for human exploration of the Mars. It is a revolutionary and evolutionary project, using a collaborative design Web site to link 16 university teams with NASA, industry, and other external institutions in a virtual organization mirroring an NASA Project Office. The MarsSuit Project will add to, focus, and galvanize the efforts of other universities into a nationwide program that will involve technology identification, assessment, and development; systems engineering; systems design; and education enhancing opportunities for participants. It will partner underrepresented minority institutions with established universities having a rich legacy of NASA research experiences. To assure relevance to NASA’s requirements there will be a strong NASA presence through a NASA MarsSuit Advisory Panel led by the EVA Program Office; Joseph J. Kosmo, JSC’s Senior EVA Project Engineer; and Astronaut Dr. Michael Gernhardt. To assure reality in the design and its ability to be reproduced by industry, an Industry Advisory Panel will be established as well, with representation from Hamilton Sundstrand and ILC Dover, leaders in the design and development of NASA space suits.
Keywords: Exploration, space flight, lunar exploration, Mars exploration, experimentation, risk contingency
Abstract: The NASA Deputy Administrator charted an internal NASA planning group to develop the rationale for exploration beyond low-Earth orbit. This team, termed the Exploration Blueprint, performed architecture analyses to develop roadmaps for how to accomplish the first steps beyond Low-Earth Orbit through the human exploration of Mars. Following the results of the Exploration Blueprint study, the NASA Administrator asked for a recommendation on the next steps in human and robotic exploration. Much of the focus during this period was on integrating the results from the previous studies into more concrete implementation strategies in order to understand the relationship between NASA programs, timing, and resulting budgetary implications. This resulted in an integrated approach including lunar surface operations to retire risk of human Mars missions, maximum use of common and modular systems including what was termed the exploration transfer vehicle, Earth orbit and lunar surface demonstrations of long-life systems, collaboration of human and robotic missions to vastly increase mission return, and high-efficiency transportation systems (nuclear) for deep-space transportation and power. The data provided in this summary presentation was developed to begin to address one of the key elements of the emerging implementation strategy, namely how lunar missions help retire risk of human missions to Mars. During this process the scope of the activity broadened into the issue of how testing in general, in various venues including the moon, can help reduce the risk for Mars missions.
Keywords: Exploration, space flight, lunar exploration, Mars exploration, experimentation, risk contingency spacecraft design, aerospace engineering
Abstract: n June 1999, the NASA Administrator chartered an internal NASA task force, termed the Decadal Planning Team, to create new integrated vision and strategy for space exploration. The efforts of the Decadal Planning Team evolved into the Agency-wide team known as the NASA Exploration Team (NEXT). This team was also instructed to identify technology roadmaps to enable the science-driven exploration vision, established a cross-enterprise, cross-center systems engineering team with emphasis focused on revolutionary not evolutionary approaches. The strategy of the DPT and NEXT teams was to “Go Anywhere, Anytime” by conquering key exploration hurdles of space transportation, crew health and safety, human/robotic partnerships, affordable abundant power, and advanced space systems performance. During the DPT and NEXT study cycles, several architectures were analyzed including missions to the Earth-Sun Libration Point, the Earth-Moon Gateway and Earth-Moon Libration Point, the lunar surface, Mars (both short and long stays), one-year round trip Mars, and near-Earth asteroids. Although there was much emphasis placed on utilization of existing launch capabilities, the team concluded that missions in near-Earth space are only marginally feasible and human missions to Mars were not feasible without a heavy lift launch capability. In addition, the team concluded that missions in Earth’s neighborhood, such as to the moon, can serve as stepping-stones toward further deep-space missions in terms of proving systems, technologies, and operational concepts.
Keywords: Space Shuttle Orbiter, aerothermodynamics, boundary layer transition
Abstract: The Space Shuttle Orbiter Aerothermodynamic Test, MH-13, was performed at Calspan/University of Buffalo Research Center in the Large Energy National Shock Tunnels facility. A highly instrumented 0.018 scale Orbiter model was tested at several flight-like reentry conditions. Data were collected for basic environmental trends, including Reynolds number and Mach number sweeps, and configuration trends, including angle of attack, side slip, and control surface deflection sweeps. Studies were also completed on windward side and wing leading edge (in the area of the shock-shock interaction) boundary layer transition. The resulting data will be used for computational data comparison and possible improvements in real-time flight support analysis methodology.
Keywords: Exploration, space flight, lunar exploration, Mars exploration, experimentation, risk contingency spacecraft design, aerospace engineering
Abstract: The material contained in this report was compiled to capture the work performed by the National Aeronautics and Space Administration’s (NASA’s) Exploration study team in the late 2002 timeframe. The “Exploration Blueprint Data Book” documents the analyses and findings of the 90-day Agency-wide study conducted from September – November 2002. The NASA Deputy Administrator requested that a study be performed with the following objectives: Develop the rationale for exploration beyond low-Earth orbit, roadmaps for how to accomplish the first steps through humans to Mars, design reference missions as a basis for the roadmaps and make recommendations on what can be done now to effect this future This planning team performed architecture analyses to develop roadmaps for how to accomplish the first steps beyond LEO through the human exploration of Mars. The reference missions resulting from the analysis performed by the Exploration Blueprint team formed the basis for requirement definition, systems development, technology roadmapping, and risk assessments for future human exploration beyond low-Earth orbit. Emphasis was placed on developing recommendations on what could be done now to effect future exploration activities. The team embraced the “Stepping Stone” approach to exploration where human and robotic activities are conducted through progressive expansion outward beyond low-Earth orbit. Results from this study produced a long-term strategy for exploration with near-term implementation plans, program recommendations, and technology investments.
Keywords: bodyweight, human body locomotion, physical exercise
Abstract: The purpose of this investigation was to determine if increasing body mass while maintaining bodyweight would affect ground reaction forces and joint kinetics during walking and running. It was hypothesized that performing gait with increased mass while maintaining body weight would result in greater ground reaction forces, and would affect the net joint torques and work at the ankle, knee and hip when compared to gait with normal mass and bodyweight. Vertical ground reaction force was measured for ten subjects (5M/5F) during walking and running on a treadmill. Subjects completed one minute of locomotion at normal mass and bodyweight and at four added mass conditions (10%, 20%, 30% and 40% of body mass) in random order. Three-dimensional joint position data were collected via videography. The addition of mass resulted in several effects. Peak impact forces and loading rates increased during walking, but decreased during running. Peak propulsive forces decreased during walking and did not change during running. Stride time increased and hip extensor angular impulse and positive work increased as mass was added for both styles of locomotion. Work increased at a greater rate during running than walking. The adaptations to additional mass that occur during walking are different than during running. Increasing mass during exercise in microgravity may be beneficial to increasing ground reaction forces during walking and strengthening hip musculature during both walking and running.
Keywords: Ergometers, exercise physiology.
Abstract: The purpose of this study was to compare the U.S. and Russian cycle ergometers, focusing on the mechanical differences of the devices and the physiological differences observed while using the devices. First, the mechanical loads provided by the U.S. Cycle Ergometer with Vibration Isolation System (CEVIS) and the Russian Veloergometer were measured using a calibration dynamometer. Results were compared and conversion equations were modeled to determine the actual load provided by each device. Second, 10 male subjects experienced with both cycling and exercise testing completed a standardized submaximal exercise test protocol on CEVIS and Veloergometer. The exercise protocol involved eight submaximal workloads each lasting three minutes for a total of 24 minutes per session, or until the end of the stage when the subject reached 85% of peak oxygen consumption or age-predicted maximum heart rate. The workload started at 50 watts (W), increased to 100 W, and then increased 25 W every three minutes until reaching a peak workload of 250 W. Physiological variables were then compared at each workload by repeated measures Analysis of Variance (ANOVA) or paired t-tests (p<0.05). While both CEVIS and Veloergometer produced significantly lower workloads than the displayed workload, CEVIS produced even lower loads than Veloergometer (p<0.05) at each indicated workload. Despite this fact, the only physiological variables that showed a significant difference between the ergometers were expired ventilation (125 – 250W), oxygen consumption (175 and 250 W), and carbon dioxide production (175 W). All other physiological data were not statistically different between CEVIS and Veloergometer.
Keywords: Aerospace medicine, exploration
Abstract: Medical requirements for the future Crew Exploration Vehicle (CEV), Lunar Surface Access Module (LSAM), advanced Extravehicular Activity (EVA) suits and Lunar habitat are currently being developed. Crews returning to the lunar surface will construct the lunar habitat and conduct scientific research. Inherent in aggressive surface activities is the potential risk of injury to crewmembers. Physiological responses to and the operational environment of short forays during the Apollo lunar missions were studied and documented. Little is known about the operational environment in which crews will live and work and the hardware that will be used for long-duration lunar surface operations.Additional informantion is needed regarding productivity and the events that affect crew function such as a compressed timeline. The Space Medicine Division at the NASA Johnson Space Center (JSC) requested a study in December 2005 to identify Apollo mission issues relevant to medical operations that had impact to crew health and/or performance. The operationally oriented goals of this project were to develop or modify medical requirements for new exploration vehicles and habitats, create a centralized database for future access, and share relevant Apollo information with the multiple entities at NASA and abroad participating in the exploration effort.
Keywords: Aerospace medicine, exploration
Abstract: The Medical Informatics and Health Care Systems group in the Office of Space Medicine at NASA Johnson Space Center (JSC) has been tasked by NASA with improving overall medical care on the International Space Station and providing insights for medical care for future exploration missions. A three day Operational and Research Musculoskeletal Summit was held on August 23-25, 2005, at Space Center Houston to review NASA’s current strategy for preflight health maintenance and injury screening, current treatment methods in-flight, and risk mitigation strategy for musculoskeletal injuries or syndromes that could occur or impact the mission. Additionally, summit participants provided a list of research topics NASA should consider to mitigate risks to astronaut health. Prior to the summit, participants participated in a web-based pre-summit forum to review the NASA Space Medical Conditions List of musculoskeletal conditions that may occur on ISS as well as the resources currently available to treat them. Data from the participants were compiled and integrated with the summit proceedings. Summit participants included experts from the extramural physician and researcher communities, and representatives from NASA Headquarters, the astronaut corps, JSC Medical Operations and Human Adaptations and Countermeasures Offices, Glenn Research Center Human Research Office, and the Astronaut Strength, Conditioning, and Reconditioning group. The recommendations in this document are based on a summary of summit discussions and the best possible evidence-based recommendations for musculoskeletal care for astronauts while on the ISS, and include recommendations for exploration class missions.
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 or other NASA-sponsored aircraft from June 30, 2006, to June 30, 2007. Included is a general overview of investigations manifested and coordinated by the Human Adaptation and Countermeasures Office. 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 about the Reduced Gravity Program.
Keywords: Exercise physiology, fitness, ergometers, pulmonary functions
Abstract: Aerobic deconditioning occurs during long-duration spaceflight despite the use of exercise countermeasures. As a part of International Space Station (ISS) medical operations, periodic tests designed to estimate aerobic capacity are performed prior to, during, and after missions of greater than 30 days in duration. These tests track changes in aerobic fitness and determine the effectiveness of exercise countermeasures. The purpose of this investigation was to compare exercise metabolic gas analysis measurements (including oxygen consumption) obtained by the Pulmonary Function System (PFS) to those collected using a reference metabolic gas analysis system: the ParvoMedics TrueOne© 2400 system (ParvoMedics, Salt Lake City, UT). This system has been extensively validated and is currently utilized by the NASA’s Exercise Physiology Laboratory for pre- and post-flight testing astronauts assigned to ISS flights. Laboratory evaluation of the PFS demonstrated that it provides similar results to those measured by the reference metabolic gas analysis system. It is recommended that the PFS be incorporated into the standard periodic fitness evaluation testing performed onboard the ISS
Keywords: Exploration, space flight, planetary aerial vehicles, planetary environments, long term space flight
Abstract: NASA has recently formed the Constellation Program to achieve the objectives of maintaining American presence in low Earth orbit, returning to the moon for purposes of establishing an outpost, and laying the foundation to explore Mars and beyond in the first half of the 21st century. The Constellation Program’s heritage rests on the successes and lessons learned from NASA’s previous human spaceflight programs: Mercury, Gemini, Apollo, Space Shuttle and International Space Station (ISS). This paper describes the rationale behind the formulation of the Constellation Program, including organizational structure, and workforce structure, as well as the approaches to requirements generation, budget formulation, operational philosophies, and procurement strategies.
Keywords: Physiology, thermoregulation, tolerances.
Abstract: This study, conducted on behalf of the EVA Physiology, Systems and Performance Project at NASA-JSC, was initiated to verify and correlate mathematical models used to predict the thermal limits of crewmembers practicing rescue techniques aboard the International Space Station (ISS) during Extravehicular Activity (EVA). While the impetus for this work came from excessive heat storage predictions by an existing EMU SINDA model, the resulting correlations and results have potential benefits for a wide range of safety-of- flight operations performed by astronauts during nominal and contingency operations.
Keywords: extravehicular activiy, medical equipment
Abstract: PURPOSE: To determine how the use of a shoulder harness during Extravehicular Activity (EVA) training activities subjectively and objectively affects the likelihood of shoulder discomfort and injury by assessment of shoulder motion and subject comfort during task performance. Data were collected during two separate phases. In phase 1, video and verbal data were collected from subjects during inverted operations at the Neutral Buoyancy Laboratory (NBL). Discomfort ratings were collected during shoulder maneuvers, and comments were recorded regarding subjective evaluations before, during, and after movements. In phase 2, sensors measured the load distribution and average pressure on the shoulders during simulated inversion in the laboratory. A force equal to the subjects’ body weight was placed on each subjects’ shoulders, and pressures were recorded during shoulder motions. During actual inversion in the NBL, subjects reported lower pain ratings while using the harness than without the harness. Subjects reported a sense of decreased shoulder range of motion while using the harness, although video records do not suggest that range of motion was affected. In general, subjects reported that the decreased sense of range of motion was the cost for the increased comfort. With both harness and no harness conditions, however, the reports of pain and discomfort were evident, suggesting that the harness may reduce discomfort, but not eliminate it.
Keywords: Radiation shielding, radiation measurement, radiation protection
Abstract: The ray-tracing technique is a powerful scientific tool that enables the analysis of radiation shielding properties of a spacecraft based on a geometry model. We discuss a method to describe spacecraft geometry as defined by one of the modern computer-aided drafting tools, ProE. A suite of software tools, called Fishbowl, is presented to convert the spacecraft geometric data to the areal density map, which is used for space radiation shielding analysis in the habitable area of the spacecraft. This tool allows users to create elaborate models of spacecraft. The areal density map is given as a function of the ray position originating from a given point inside a spacecraft or human body. The map is then input to the high-charge-and-energy transport computer program (HZETRN) code developed at NASA. The HZETRN code calculates energy spectra of high-energy particles passing through the spacecraft material of a certain thickness and takes into account fragments created by nuclear reactions. The flux at a dose point can be determined with this tool, as well as a false color ball displaying "hot" and "cold" spots of radiation penetrating the spacecraft wall, which can be useful for suggesting more efficient spacecraft geometries for radiation shielding. In other words, the directionality of the received radiation is described for the analysis of the spacecraft design to make it more optimal for radiation protection. Two examples of the validation of the ProE-based model with a simpler OpenGL/C++ in-house tool are presented. Several dose rate data are presented at points within the Lunar Transfer Vehicle and within the astronaut’s body received from space radiation. A human phantom model constructed from several parts was introduced in ProE too. Examples of radiation shielding calculations for lunar mission are described.
Keywords: International Space Station; payload stations; access control; JEM; Columbus-EPF; Express Logistics Carrier; U.S. truss
Abstract: External payload accommodations are provided at attachment sites on the U.S.-provided Express Logistis Carrier, U.S. truss, Japanese Experiment Module-Exposed Facility (JEM-EF), and Columbus-EPF (External Payload Facilities). The integrated truss segment attaches solar and thermal control arrays to the International Space Station (ISS), houses cable distribution trays and spacewalk support equipment, and provides for extravehicular robotic accommodations. The JEM-EF accommodates up to eight payloads, which can be serviced via the JEM PM airlock and dedicated robotic arm. The Columbus-EPF can accommodate two zenith- and nadir-looking payloads. The ISS command and data handling (C&DH) system consists of hardware and software that provide services for command, control, and data distribution for all ISS systems, subsystems, and payloads. The system-level C&DH architecture contains redundant command and control (C&C) multiplexers/demultiplexers (MDMs) and MIL-STD-1553B control buses. The payload service includes the payload MDM for low-rate data link (LRDL) data and command distribution, and a high-rate data link (HRDL) for payload-to-payload communication and data-downlink service. LRDL data are downlinked via the HRDL to the ground. Safety-related data are routed via the C&C MDM to S-band data services for downlink. The Personal Computer System is used by the crew for command and display interface.
Keywords: meteorites; robotics; Mars exploration; lunar exploration; comets; electric batteries; atmospheric entry; artificial gravity; robot sensors; oxygen analyzers
Abstract: The Biennial Research and Technology Development Report is a compilation of advances in research and technology accomplished by Johnson Space Center (JSC) engineers and scientists. It contains astromaterials research and exploration science, space life science, engineering, extravehicular activity, White Sands Test Facility (WSTF), and education and center operations. Examples of astromaterials research and exploration science demonstrate major improvements in handling and analysis of extremely small solar and asteroid particles. Space life sciences research includes neurovestibular research and arterial and cardiac function in six-degree head-down tilt bed rest. Engineering research includes the designing of a prototype ultra-wide-band tracking system for lunar operations where navigation tools are not available. JSC is also studying ramifications of applying laser peening to friction stir welding for space operations. The extravehicular program is developing medical and engineering practices to maintain a productive healthy crew during difficult and dangerous work situations. WSTF’s research on ignition testing on multiple spacesuit materials placed in various oxygen concentrations is critical for future exploration missions. JSC’s commitment to science, technology, engineering, and math educational programs for elementary schools through post-doctorate programs is strong. Finally, advances in technology are needed for JSC’s work with the community, and for facilitating space center operations.
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