SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Topic considered include: environmental health services; health physics; ionizing radiation; pollution control; contamination investigations; natural resources; surface water; health hazard evaluations; combustion gas; launch support; asbestos; hazardous noise; and ventilation.
A hazard to all spacecraft orbiting the earth and exploring the unknown in deep space is the existence of a harsh and ever changing environment with its subsequent effects. Some of these environmental hazards, such as plasma, extreme thermal excursions, meteoroids, and ionizing radiation result from natural sources, whereas others, such as orbital debris and neutral contamination are induced by the presence of spacecraft themselves. The subsequent effects can provide damaging or even disabling effects on spacecraft, its materials, and its instruments. In partnership with industry, academia, and other government agencies, National Aeronautics & Space Administration's (NASA's) Space Environments & Effects (SEE) Program defines the space environments and advocates technology development to accommodate or mitigate these harmful environments on the spacecraft. This program provides a very comprehensive and focused approach to understanding the space environment, to define the best techniques for both flight and ground-based experimentation, to update the models which predict both the environments and the environmental effects on spacecraft, and finally to ensure that this information is properly maintained and inserted into spacecraft design programs. This paper will provide an overview of the Program's purpose, goals, database management and technical activities. In particular, the SEE Program has been very active in developing improved ionizing radiation models and developing related flight experiments which should aid in determining the effect of the radiation environment on modern electronics.
Galactic cosmic rays (GCR) consisting of nuclei of all the known elements with kinetic energies extending from tens to millions of MeV pose a significant health hazard to future deep space operations. Even half of the radiation exposures expected in ISS will result from GCR components. The biological actions of these radiations are known to depend on the details of the energy deposition (not just linear energy transfer, LET, but the lateral dispersion of energy deposition about the particle track). Energy deposits in tissues are dominated by the transfer of tens to hundreds of eV to the tissue's atomic electrons. In the case of low LET radiations, the collisions are separated by large dimensions compared to the size of important biomolecular structures. If such events are also separated in time, then the radiation adds little to the background of radicals occurring from ordinary metabolic processes and causes little or no biological injury. Hence, dose rate is a strong determinant of the action of low LET exposures. The GCR exposures are dominated by ions of high charge and energy (HZE) characterized by many collisions with atomic electrons over biomolecular dimensions, resulting in high radical- density events associated with a few isolated ion paths through the cell and minimal dose rate dependence at ordinary exposure levels. The HZE energy deposit declines quickly laterally and merges with the background radical density in the track periphery for which the exact lateral distribution of the energy deposit is the determinant of the biological injury. Although little data exists on human exposures from HZE radiations, limited studies in mice and mammalian cell cultures allow evaluation of the effects of track structure on shield attenuation properties and evaluation of implications for dosimetry. The most complete mammalian cell HZE exposure data sets have been modeled including the C3H10T1/2 survival and transformation data of Yang et al., the V79 survival and mutation data of various groups, and the Harderian gland tumor data of Alpen et al. Model results for the Harderian gland tumor data in comparison with data from Alpen et al. The Harderian target cell initiation cross section compares closely with the transformation cross section found for the C3H10T1/2 cell transformation data of Yang et al. The most notable feature of the cross sections are the multivalued cross sections for a given LET which implies the corresponding relative biological effectiveness (RBE) is dependent not only on the LET but also the ion type. This fact is at variance with the latest ICRP recommended quality factor which is a defined function of only the LET.
A space-qualified silicone polymer, DC93-500 (Dow Corning, Midland, MI), has been used as a spacecraft solar cell adhesive and has been proposed for use in a Fresnel lens solar concentrator for space power applications. Applications of DC93-500 for exterior space system surfaces require an understanding of its overall space environmental durability. Vacuum ultraviolet (VUV) radiation is among the space environment elements that can be hazardous to the properties of DC93-500, causing degradation in optical and mechanical properties. For materials or components that have not been tested previously for long-duration performance in space, such as DC93-500 in freestanding film form, ground laboratory testing is an important tool for assuring durability. However, differences between the space environment and ground laboratory testing environments lead to complexities in interpreting the ground test results. Two important differences between space and laboratory vacuum ultraviolet exposure conditions are irradiance spectra and light intensity. These important differences were the basis for laboratory experiments conducted to examine VUV wavelength dependence and VUV intensity dependence of DC93-500 degradation. Testing conducted at the NASA Glenn Research Center along with additional data provided through a grant with the University of Nebraska-Lincoln, has advanced the understanding of VUV effects on DC93-500 and has provided important conclusions regarding the use of ground laboratory VUV testing to predict the space environment performance of DC93-500.
A new NASA document entitled "Terrestrial Environment (Climatic) Criteria Handbook for Use in Aerospace Vehicle Development (NASA-HDBK-1001A) has been developed. The Handbook provides terrestrial environment information, data bases, models, recommendations, etc. for use in the design, development, trade studies, testing, and mission analyses for space (or launch) .vehicles. This document is organized into fourteen specific natural environment disciplines of which some are winds, atmospheric models, thermal radiation, precipitation-for-icing, cloud cover, atmospheric electricity, geologic hazards, toxic chemical release by propulsion systems, and sea state. Atmospheric phenomena play a significant role in the design and flight of aerospace vehicles and in the integrity of the associated aerospace systems and structures. Environmental design criteria guidelines in this document are based on measurements and observations of atmospheric and climatic phenomena relative to various aerospace development, operational, and vehicle launch locations. The natural environment criteria guidelines data presented in this Handbook were formulated based on discussions with and requests from engineers involved in aerospace vehicle development and operations. Therefore, they represent responses to actual engineering problems and are not just a general compilation of environmental data. The Handbook addresses the basis for the information presented, the interpretations of the terrestrial environment guideline given in the Handbook, and its application to the development of aerospace vehicle design requirements. Specific examples of the Handbook content and associated "lessons lenmed" are given in this paper.
A new NASA document entitled "Terrestrial Environment (Climatic) Criteria Handbook for Use in Aerospace Vehicle Development (NASA-HDBK-IOO1A) has been developed. The Handbook provides terrestrial environment information, data bases, models, recommendations, etc. for use in the design, development, trade studies, testing, and mission analyses for space (or launch) vehicles. This document is organized into fourteen specific natural environment disciplines of which some are winds, atmospheric models, thermal radiation, precipitation-for-icing, cloud cover, atmospheric electricity, geologic hazards, toxic chemical release by propulsion systems, and sea state. Atmospheric phenomena play a significant role in the design and flight of aerospace vehicles and in the integrity of the associated aerospace systems and structures. Environmental design criteria guidelines in this document are based on measurements and observations of atmospheric and climatic phenomena relative to various aerospace development, operational, and vehicle launch locations. The natural environment criteria guidelines data presented in this Handbook were formulated based on discussions with and requests from engineers involved in aerospace vehicle development and operations. Therefore, they represent responses to actual engineering problems and are not just a general compilation of environmental data. The Handbook addresses the basis for the information presented, the interpretations of the terrestrial environment guideline given in the Handbook, and its application to the development of aerospace vehicle design requirements. Specific examples of the Handbook content and associated "lessons lenmed" are given in this paper.
NASA utilizes an evidence based system to perform risk assessments for the human system for spaceflight missions. The center of this process is the multi-disciplinary Human System Risk Board (HSRB). The HSRB is chartered from the Chief Health and Medical Officer (OCHMO) at NASA Headquarters. The HSRB reviews all human system risks via an established comprehensive risk and configuration management plan based on a project management approach. The HSRB facilitates the integration of human research (terrestrial and spaceflight), medical operations, occupational surveillance, systems engineering and many other disciplines in a comprehensive review of human system risks. The HSRB considers all factors that influence human risk. These factors include pre-mission considerations such as screening criteria, training, age, sex, and physiological condition. In mission factors such as available countermeasures, mission duration and location and post mission factors such as time to return to baseline (reconditioning), post mission health screening, and available treatments. All of the factors influence the total risk assessment for each human risk. The HSRB performed a comprehensive review of all potential inflight medical conditions and events and over the course of several reviews consolidated the number of human system risks to 30, where the greatest emphasis is placed for investing program dollars for risk mitigation. The HSRB considers all available evidence from human research and, medical operations and occupational surveillance in assessing the risks for appropriate mitigation and future work. All applicable DRMs (low earth orbit for 6 and 12 months, deep space for 30 days and 1 year, a lunar mission for 1 year, and a planetary mission for 3 years) are considered as human system risks are modified by the hazards associated with space flight such as microgravity, exposure to radiation, distance from the earth, isolation and a closed environment. Each risk has a summary two-page assessment representing the state of knowledge/evidence of that risk, available risk mitigations, traceability to the Space Flight Human System Standards (SFHSS) and program requirements, and future work required. These data then can drive coordinated budgets across the Human Research Program, the International Space Station, Crew Health and Safety and Advanced Exploration System budgets to provide the most economical and timely mitigations. The risk assessments were completed for the 6 DRMs and serve as the baseline for which subsequent research and technology development and crew health care portfolios can be assessed. The HSRB reviews each risk at least annually or when new evidence/information is available that adds to the body of evidence. The current status of each risk can be reported to program management for operations, budget reviews and general oversight of the human system risk management program.
On April 22nd, 2017, the Cassini spacecraft made its final close targeted flyby of Titan, placing Cassini in the gap between Saturn and its innermost D-ring for the first time ever of its mission at Saturn. Cassini proceeded to fly through this region 22 times, and on September 15th, 2017, Cassini plunged into Saturn’s atmosphere, concluding a remarkable, nearly 20-year mission. The attitude control subsystem performance during these 22 “proximal” orbits exceeded expectations. Prior to the proximal orbits mission, the effects of dust hazards, Saturn atmospheric drag torque on Cassini’s control authority, radiation on the sensitive instruments, bright body interferences to the star tracker, pointing discrepancies caused by trajectory deviations, and possible fault protection scenarios were assessed. This paper discusses the results of these risks experienced by the attitude control subsystem over the proximal orbits mission, any interesting telemetry observed, as well as any last minute procedural changes implemented along the way.
The principal occupational health problem generally associated with high intensity arc lamps results from exposure of the eye and skin to ultraviolet radiation. Occasionally, the chorioretinal burns are of concern. The eye is generally more susceptible than the skin to injury from high intensity optical radiation sources whether ultraviolet, visible or infrared. Recent developments in technology have shown that some high intensity optical radiation sources which have output parameters greatly different from those encountered in the natural environment present a serious chorioretinal burn hazard.
This presentation has been a brief snapshot discussing electronics and Exploration-related challenges. The vision for Space Exploration creates a new paradigm for NASA missions. This includes transport (Crew Exploration Vehicle-CEV), and lunar and Mars Exploration and human presence. If one considers the additional hazards faced by these concepts versus more traditional NASA missions, multiple challenges surface for reliable utilization of electronic parts. The true challenge is to provide a risk as low as reasonably achievable (ALARA-a traditional biological radiation exposure term), while still providing cost effective solutions. This presentation also discusses the hazard for electronic parts and exploration, the types of electronic parts for exploration, and the critical juncture for space usage of commercial changes in the electronics world.
Radiation shielding analyses are performed for candidate lunar base habitation modules. The study primarily addresses potential hazards due to contributions from the galactic cosmic rays. The NASA Langley Research Center's high energy nucleon and heavy ion transport codes are used to compute propagation of radiation through conventional and regolith shield materials. Computed values of linear energy transfer are converted to biological dose-equivalent using quality factors established by the International Commision of Radiological Protection. Special fluxes of heavy charged particles and corresponding dosimetric quantities are computed for a series of thicknesses in various shield media and are used as an input data base for algorithms pertaining to specific shielded geometries. Dosimetric results are presented as isodose contour maps of shielded configuration interiors. The dose predictions indicate that shielding requirements are substantial, and an abbreviated uncertainty analysis shows that better definition of the space radiation environment as well as improvement in nuclear interaction cross-section data can greatly increase the accuracy of shield requirement predictions.
There is a robust and effective psychological support system on the ISS. Future exploration missions however will expose the crew to unprecedent hazards, included extended durations of isolation and confinement, distance from earth, galactic cosmic radiation. Research in spaceflight and terrestrial analogs demonstrate that while most participants remain psychologically healthy and high performing, some risks do emerge, including declines in positive adaptation and emotion recognition. We must understand and implement the right countermeasures to support the psychological health and performance in future exploration missions. Future challenges include high fidelity research platforms and characterizing effects of multiple hazards.
Our ability to confidently develop appropriate countermeasures for radiations in space in terms of shielding and design of a spacecraft, the mission scenario, or chemoprevention is severely limited by the uncertainties in both the risk itself and the change in that risk with intervention. Despite the fact that the risk of carcinogenesis from exposures of personnel to radiations on long-term missions is considered one of the worst hazards in space, only a limited amount of in-vivo data exist for tumor induction from exposures to protons or energetic heavy ions (HZEs) at lower doses. The most extensive work remains the landmark study. for tumor development in the harderian gland of the mouse. The objective of this study is to characterize the level of risk for tumor induction in another relevant animal model. Subsequent experiments are designed to test the hypothesis that the level of risk can be reduced by pharmaceutical intervention in the promoting and progressing stages of the disease rather than in the initiating stage. The work presented here results from a cooperative effort on the part of investigators from two projects of the Radiation-Effects Team of the National Space Biomedical Research Institute (NSBRI). The collaborating projects are the Core Project which is investigating the risk of carcinogenesis in Sprague-Dawley rats and the Chemoprevention Project which is investigating the ability of Tamoxifen to reduce the number of malignant tumors in the irradiated animals. Research at the cellular and subcellular levels is being conducted in two other projects of the Radiation-Effects Team, Cytogenetics with J. R. Williams as Principal Investigator and Mutations from Repeated DNA Sequences. Results for these other projects also are being presented at this Workshop.
The effects of nonionizing electromagnetic (EM) field interactions with the human body were reported and human related studies were collected. Nonionizing EM fields are linked to cancer in humans in three different ways: cause, means of detection, and effective treatment. Bad and benign effects are expected from nonionizing EM fields and much more knowledge is necessary to properly categorize and qualify EM field characteristics. It is concluded that knowledge of the boundary between categories, largely dependent on field intensity, is vital to proper future use of EM radiation for any purpose and the protection of the individual from hazard.
Lunar dust causes a variety of problems for spacecraft. It can obscure vision, clog equipment, cause seal failures and abrade surfaces. Additionally, lunar dust is potentially toxic and therefore hazardous to astronauts. Lunar dust can be activated by meteorites, UV radiation and elements of solar wind and, if inhaled, could produce reactive species in the lungs (freshly fractured quartz). Methods of lunar dust deactivation must be determined before new lunar missions. This requires knowledge of how to reactivate lunar dust on Earth - thus far crushing/grinding, UV activation and heating have been tested as activation methods. Grinding of lunar dust leads to the production of hydroxyl radicals in solution and increased dissolution of lunar simulant in buffers of different pH. Decreases in pH lead to increased lunar simulant leaching. Additionally, both ground and unground lunar simulant and unground quartz have been shown to promote the production of IL-6 and IL-8, pro-inflammatory cytokines, by alveolar epithelial cells. The results suggest the need for further studies on lunar dust and simulants prior to returning to the lunar surface.
Spaceflight crews will be exposed to levels of radiation which exceed those experienced on the ground. In order to reduce the uncertainty in the evaluation of risks it is necessary to validate the responses of biological systems in space under conditions which simulate exposure levels expected during exploration class missions. The LifeSat system provides the experimental capabilities to satisfy these goals. Specifically, LifeSat is capable of long duration flights of up to 60 days, is able to fly directly into trapped radiation belts and in circular or eccentric polar orbits, has the ability to provide artificial gravity and imposes fewer restrictions than the STS on the use of hazardous materials such as chemical fixatives. These features along with reference missions and experiments are discussed with respect to radiation research goals.
The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. During the last couple of years, four EOS science missions were launched, representing observations of (i) total solar irradiance, (ii) Earth radiation budget, (iii) land cover & land use change, (iv) ocean processes (vector wind, sea surface temperature, and ocean color), (v) atmospheric processes (aerosol and cloud properties, water vapor, and temperature and moisture profiles), and (vi) tropospheric chemistry. In succeeding years many more satellites will be launched that will contribute immeasurably to our understanding of the Earth's environment. In this presentation I will describe how scientists are using NASA's Earth science data to examine land use and natural hazards, environmental air quality, including: dust storms over the worlds deserts, cloud and radiation properties, sea surface temperature, and winds over the ocean, with a special emphasis on satellite observations available for studying the southern African environment.
Zeroth order, maintenance of human health requires supportive protection from the hazards of space, including supplying breathable air, comfortable temperatures, a supportive diet/nutrition, radiation protection, and sufficient gravity to avoid the combinatorial impacts of such effecting human operability and health. Spacecraft operability must be “fail-safe” to ensure these basic human life support conditions are maintained throughout the mission and the mission(s) must be affordable. There are known effects and unknowns effects regarding aspects of human health for Mars duration missions. Mars has the order of a third g. We have no data regarding the health impacts of this on humans or the combinatorial effects associated with 45% GCR on the Martian surface over time. There is a suspicion that if humans survive such conditions over long times they will evolve to living at reduced g and become “Martians”. Cascading failures and subcritical degradations in systems of systems causing an overall unrecoverable failure are a potential issue. There are two exremely complex systems associated with humans-Mars missions: the technical, engineering, and architectural system of systems that enable the mission and the humans. Both need to be mutually configured and operated to mitigate the overall risks and hazards of the mission. Regarding the humans that mitigation includes both the mission risks and supporting-to-increasing the human immune and other concomitant physiological systems. This report will summarize the risks, current mitigation approaches, and putative approaches including lifestyle, nutrition, and “wellness” approaches to possibly improve the human capacity to withstand the large number of combinatorial human physiological rigors of the missions. The wellness observations also apply to and are derived from Earth terrestrial applicable research.