Keywords: weightlessness; parabolic flight; zero gravity; plant growth; astronaut health
Abstract: This document represents a summary of medical and scientific evaluations conducted on board the Zero G and other NASA sponsored aircraft from June 2011 to June 2012. A general overview of investigations manifested and coordinated by the Human Adaptation and Countermeasures Division is included. A collection of brief reports that describe tests conducted on board 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: spacecraft design, meteoroids, sheilding, protection
Abstract: The Apollo program drove the development of spacecraft meteoroid protection in the U.S. and provided the core technology used on succeeding space programs. The uncertain likelihood of a mission-ending collision with a meteoroid and the unknown consequences of a collision with particles at the very large speeds typical of meteoroids made it crucial to better understand the risk of meteoroid impact. While there are extensive records of the design and analysis of the Apollo spacecraft meteoroid shielding, the information is spread across a variety of archives and personal files. This is the first report to assemble the sources into a technical history. This report includes sections on the Apollo shielding requirements, Apollo meteoroid protection analysis results, the Manned Spacecraft Cetner Hypervelocity Impact Test Program, Command and Service Modules, the Lunar Module, and the Extravehicular Mobility Unit.
Keywords: radiation effects; biological effects; radiation exposure; radiation hazards; radiation injuries; radiation protection; radiation sickness; radiation tolerance; human tolerance
Abstract: Uncertainties in estimating health risks from galactic cosmic rays are a major limitation to the length of space missions and the evaluation of potential risk mitigations. NASA limits astronaut exposures to a 3% risk of exposure-induced death and protects against uncertainties in risks projections using an assessment of 95% confidence intervals in the projection model. Revisions to the NASA projection model for lifetime cancer risks from space radiation and new estimates of model uncertainties are described. Our report reviews models of space environments and transport code predictions of organ exposures, and characterizes uncertainties. We summarize recent analysis of low linear energy transfer radio-epidemiology data, including revision to the Japanese A-bomb survivor dosimetry, longer follow-up of exposed cohorts, and reassessments of dose and dose-rate reduction effectiveness factors. We compare newer projections and uncertainties with earlier estimates. Current understanding of radiation quality effects and recent data on factors of relative biological effectiveness and particle track structure are reviewed. Results from radiobiology experiments provide new information on solid cancer and leukemia risks from heavy ions; radiation quality effects are described. New findings and knowledge are used to revise the NASA risk projection model for space radiation cancer risks.
Keywords: Apollo lunar module; lunar landing; landing gear; touchdown; lunar soil; lunar surface
Abstract: The primary objective of this paper is to present an analysis and a historical review of the Apollo Lunar Module landing dynamics from the standpoint of touchdown dynamic stability, landing system energy absorption performance, and evaluation of the first-order terms of lunar soil mechanical properties at the Apollo 11 landing site. The first-order terms of lunar surface mechanical properties consisted primarily of the surface bearing strength and sliding friction coefficient. The landing dynamic sequence started at first footpad contact. The flight dynamics data used to assess the Apollo 11 landing system performance and the lunar soil mechanical properties included the body axis pitch, roll, and yaw rate time histories as measured by the on-board guidance computer during the Apollo 11 Lunar Module touchdown maneuver, and the landing gear stroke data derived from post-landing photographs. The conclusions drawn from these studies were that the landing gear system performance was more than adequate from a stability and energy absorption standpoint for all Apollo lunar landings, and the lunar soil parameters were well within the limits of the design assumptions for all Apollo landing sites.
Keywords: galactic cosmic rays; galactic radiation; radiation measurement; flux density
Abstract: The purpose of this work is to provide an accurate Galactic Cosmic Ray (GCR) energy spectrum that can be used by radiation health physicists for astronaut exposures and for Single Event Effect (SEE) rate prediction codes CRÈME-MC and CREME96. GCRs are the major cause of "quiet time" SEEs in spacecraft in the solar system and beyond. Accurate knowledge of the GCR spectrum is needed, especially during solar minimum when the GCR flux is at its maximum. All GCR energy spectra reported in this paper apply in free space – beyond the Earth's magnetosphere. An appropriate magnetic cutoff code should be used to get the GCR flux within the Earth's magnetic field. New results presented here model the "quiet time" GCR flux from 1955 to 2012 and provide the most comprehensive comparison compiled, to date, between model and GCR in-flight measurements made above the magnetic cutoff, from balloons (high latitude) and satellites (high altitude). The Badhwar-O’Neill model parameters are uniquely influenced by measurements from the NASA Advanced Composition Explorer Cosmic Ray Isotope Spectrometer that is measuring the low energy spectrum for all ions from lithium to nickel. This is a significant improvement to the overall accuracy of modeling the true GCR spectrum.
Keywords: extravehicular activity; decompression sickness; hypoxia; controlled atmospheres; environmental control
Abstract: Extravehicular activity (EVA) is at the core of a manned space exploration program. Some elements of exploration may be safely and effectively performed by robots, but certain critical elements will require the trained, assertive, and reasoning mind of a human crewmember. To effectively use these skills, NASA needs a safe, effective, and efficient EVA component integrated into the human exploration program. The EVA preparation time should be minimized and the suit pressure should be low to accommodate EVA tasks without undue fatigue, physical discomfort, or suit-related trauma. Commissioned in 2005, the Exploration Atmospheres Working Group (EAWG) had the primary goal of recommending to NASA an internal environment that allowed efficient and repetitive EVAs for missions that were to be enabled by the former Constellation Program. At the conclusion of the EAWG meeting, the 8.0 psia and 32% oxygen (O2) environment were recommended for EVA-intensive phases of missions. This paper provides a literature review of the human health and performance risks associated with the 8 psia / 32% O2 environment.
Keywords: International Space Station; spaceborne experiments;cells (biology); microbiology; tissue engineering
Abstract: In March 2013, an external panel of experts from various cell biology, microbiology, and tissue engineering fields was convened to develop and recommend a set of scientific requirements that could be used to steer strategic planning and tactical execution of these fields of research on the International Space Station (ISS) National Laboratory. Panel discussions focused on feasibility assessments, culture and specimen types, the in-flight culture environment, in-flight experiment handling and processing, and sample return. The panel made 41 recommendations for the future of cell biology experiments on ISS National Laboratory. Recommendations fall within these categories: overarching strategies; cryopreservation ; culture ; sample analysis and storage ; and quality. Panel members discussed the need to establish a world-class research facility that can address the 2011 National Research Council Decadal Survey mandate to provide research that both “enables space exploration” and is “enabled by access to space.” Panel members were made aware that requirements should be implemented immediately and with urgency. Furthermore, the panel was asked to elucidate new sample processing and analysis capabilities needed to maximize scientific return for the benefit of human health and quality of life.
Keywords: acceleration; acceleration tolerance; acceleration protection; impact; landings; escape systems
Abstract: Currently, NASA occupant protection standards are primarily based on the Multi-axial Dynamic Response Criteria, which NASA refers to as the Brinkley Dynamic Response Criterion (BDRC). The BDRC was developed by the United States Air Force and adopted by NASA in the mid-1990s during the development of the Assured Crew Return Vehicle and evaluation of the Soyuz three-person crew vehicle landing impact tests. BDRC criteria includes a dynamic model, used to evaluate the risk of injury using a series of lumped parameter models with mass, spring, and damping properties. During BDRC development, model responses were related to human injury data to develop low, medium, and high injury risk limits. Because of its simplicity, the BDRC is attractive to designers. However, because of the simplifications and the specific characteristics of the seating systems used, application criteria or rules are necessary to correctly apply the model and interpret the results. In addition, several limitations have been identified that limit the injury prediction capabilities of the model. The purpose of this document is to review the BDRC development, document the rules necessary to apply the BDRC, identify limitations for NASA’s application, and describe additional testing and analysis methods necessary to supplement the BDRC.
Keywords: sleep; fatigue; spacecraft environments; astronaut training; long duration space flight
Abstract: In 2009, the NASA Human Research Program Behavioral Health and Performance (BHP) Element, in collaboration with the Space Medicine Division, implemented a study to characterize the subjective sleep experience of astronauts during Space Shuttle missions. Study participants were NASA astronauts who have flown Shuttle since the “Return to Flight” missions (STS-114) in 2005, through those on STS-130 in February 2010. A total of 64 astronauts completed both the survey and the interview; an additional 10 astronauts completed just the interview. Content of the survey relates to sleep during Shuttle missions and sleep on Earth, including factors that may inhibit sleep; and specific countermeasure strategies used and their subjective effectiveness. Follow-up interviews provided an opportunity to gather additional information on sleep stressors and countermeasures. The survey results indicated individual variability exists with regard to sleep in flight. Some factors predictive of reported sleep quality were identified. Results from this investigation will be used to provide recommendations to astronauts preparing for spaceflight missions to the International Space Station, the Soyuz, and those training for future missions. This study will also help identify gaps related to needed countermeasure development and implementation, and provide insight into the use of sleep medications in space.
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