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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.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Blood volume and orthostatic responses of men and women to a 13-day bedrest

Changes in blood volume during space flight are thought to contribute to decrements in postflight orthostatic function. The purpose of this study was to determine whether gender affects red cell mass and plasma volume during a short exposure to simulated microgravity, and whether gender differences in orthostatic tolerance ensure. Methods: Ten men (31.5 plus or minus 5.2 years, STD) and eleven normally menstruating women (33.3) plus or minus 6.0 STD) underwent 13 days of 6 degree head-down bedrest. Plasma volume (Iodine 125 labeled human serum albumin) and red cell mass (Carbon 51 labeled red blood cells) were measured before bedrest and on bedrest day 13. On the same days, orthostatic tolerance (OT) was determined as the maximal pressure during a presyncopalimited lower body negative pressure test. Results: Plasma volume (PV) and red cell mass (RCM) decreased in both groups with a greater PV decrease (P less than 0.05) in men (6.3 plus or minus 0.7 ml/kg) than in women (4.1 plus or minus 0.6 ml/kg). Decreases in red cell mass were similar (1.7 plus or minus 0.2 ml/kg in men and 1.7 plus or minus 0.2 ml/kg in women). OT was similar for men and women before bedrest (minus 78 plus or minus 6 mmHg in men versus minus 70 plus or minus 4 mmHg in women) and decreased by a similar degree (by an average of 11 mmHg in both groups) after bedrest. The changes in OT did not correlate with changes in plasma volume during bedrest (r(exp 2) = 0.002). Conclusion: Thus, although female hormones may protect PV during bedrest, they do no appear to offer an advantage in terms of loss of orthostatic function.

Fortney, S.↗
NASA NTRS1995

Program Implements Variable-Sampling Procedures

MIL-STD-414 Variable Sampling Procedures (M414) computer program developed to automate calculations and acceptance/rejection procedures of MIL-STD-414, "Sampling Procedures and Tables for Inspection by Variables for Percent Defective." M414 automates entire calculation-and-decision process by use of computational algorithms determining threshold acceptability values for lots. Menu-driven and user-friendly. Reduces burden of manual operations, promoting variable-sampling practice in industry in lieu of "go/no-go" inspection. Written in BASIC.

Huang, Zhaofeng↗
NASA NTRS1996

Interface Circuit For Connecting Instruments To Computers

Circuit card designed to act as interface between K-bus remote terminal. Enables digital communication between electronic instrumentation designed to communicate with other equipment via K-bus and control and telemetry-monitoring computer designed to communicate with other equipment via MIL-STD-1553B (or MIL-STD-1773) bus. Provides K-bus interface for as many as four instrumentation circuit cards.

Katz, Richard B.↗
NASA NTRS2000

A Cost Effective System Design Approach for Critical Space Systems

NASA-JSC required an avionics platform capable of serving a wide range of applications in a cost-effective manner. In part, making the avionics platform cost effective means adhering to open standards and supporting the integration of COTS products with custom products. Inherently, operation in space requires low power, mass, and volume while retaining high performance, reconfigurability, scalability, and upgradability. The Universal Mini-Controller project is based on a modified PC/104-Plus architecture while maintaining full compatibility with standard COTS PC/104 products. The architecture consists of a library of building block modules, which can be mixed and matched to meet a specific application. A set of NASA developed core building blocks, processor card, analog input/output card, and a Mil-Std-1553 card, have been constructed to meet critical functions and unique interfaces. The design for the processor card is based on the PowerPC architecture. This architecture provides an excellent balance between power consumption and performance, and has an upgrade path to the forthcoming radiation hardened PowerPC processor. The processor card, which makes extensive use of surface mount technology, has a 166 MHz PowerPC 603e processor, 32 Mbytes of error detected and corrected RAM, 8 Mbytes of Flash, and I Mbytes of EPROM, on a single PC/104-Plus card. Similar densities have been achieved with the quad channel Mil-Std-1553 card and the analog input/output cards. The power management built into the processor and its peripheral chip allows the power and performance of the system to be adjusted to meet the requirements of the application, allowing another dimension to the flexibility of the Universal Mini-Controller. Unique mechanical packaging allows the Universal Mini-Controller to accommodate standard COTS and custom oversized PC/104-Plus cards. This mechanical packaging also provides thermal management via conductive cooling of COTS boards, which are typically designed for convection cooling methods.

Abbott, Larry Wayne↗
NASA NTRS2001

Experimental Structural Dynamic Response of Plate Specimens Due to Sonic Loads in a Progressive Wave Tube

The objective of the current study was to assess the repeatability of experiments at NASA Langley's Thermal Acoustic Fatigue Apparatus (TAFA) facility and to use these experiments to validate numerical models. Experiments show that power spectral density (PSD) curves were repeatable except at the resonant frequencies, which tended to vary between 5 Hz to 15 Hz. Results show that the thinner specimen had more variability in the resonant frequency location than the thicker sample, especially for modes higher than the first mode in the frequency range. Root Mean Square (RMS) tended to be more repeatable. The RMS behaved linearly through the SPL range of 135 to 153 dB. Standard Deviations (STDs) of the results tended to be relatively low constant up to about 147 dB. The RMS results were more repeatable than the PDS results. The STD results were less than 10% of the RMS results for both the 0.125 in (0.318 cm) and 0.062 in (0.1588 cm) thick plate. The STD of the PSD results were around 20% to 100% of the mean PSD results for non-resonant and resonant frequencies, respectively, for the 0.125 in (0.318 cm) thicker plate and between 25% to 125% of the mean PSD results, for nonresonant and resonant frequencies, respectively, for the thinner plate.

Betts, Juan F.↗
NASA NTRS2001

Flight Computer Design for the Space Technology 5 (ST-5) Mission

As part of NASA's New Millennium Program, the Space Technology 5 mission will validate a variety of technologies for nano-satellite and constellation mission applications. Included are: a miniaturized and low power X-band transponder, a constellation communication and navigation transceiver, a cold gas micro-thruster, two different variable emittance (thermal) controllers, flex cables for solar array power collection, autonomous groundbased constellation management tools, and a new CMOS ultra low-power, radiation-tolerant, +0.5 volt logic technology. The ST-5 focus is on small and low-power. A single-processor, multi-function flight computer will implement direct digital and analog interfaces to all of the other spacecraft subsystems and components. There will not be a distributed data system that uses a standardized serial bus such as MIL-STD-1553 or MIL-STD-1773. The flight software running on the single processor will be responsible for all real-time processing associated with: guidance, navigation and control, command and data handling (C&DH) including uplink/downlink, power switching and battery charge management, science data analysis and storage, intra-constellation communications, and housekeeping data collection and logging. As a nanosatellite trail-blazer for future constellations of up to 100 separate space vehicles, ST-5 will demonstrate a compact (single board), low power (5.5 watts) solution to the data acquisition, control, communications, processing and storage requirements that have traditionally required an entire network of separate circuit boards and/or avionics boxes. In addition to the New Millennium technologies, other major spacecraft subsystems include the power system electronics, a lithium-ion battery, triple-junction solar cell arrays, a science-grade magnetometer, a miniature spinning sun sensor, and a propulsion system.

Speer, David↗
NASA NTRS2003

Standard Spacecraft Interfaces and IP Network Architectures: Prototyping Activities at the GSFC

Advancements in fright semiconductor technology have opened the door for IP-based networking in spacecraft architectures. The GSFC believes the same signlJicant cost savings gained using MIL-STD-1553/1773 as a standard low rate interface for spacecraft busses cun be realized for highspeed network interfaces. To that end, GSFC is developing hardware and software to support a seamless, space mission IP network based on Ethernet and MIL-STD-1553. The Ethernet network shall connect all fright computers and communications systems using interface standards defined by the CCSDS Standard Onboard InterFace (SOIF) Panel. This paper shall discuss the prototyping effort underway at GSFC and expected results.

Schnurr, Richard↗
NASA NTRS2003

Reference Material Kydex(registered trademark)-100 Test Data Message for Flammability Testing

The Marshall Space Flight Center (MSFC) Materials and Processes Technical Information System (MAPTIS) database contains, as an engineering resource, a large amount of material test data carefully obtained and recorded over a number of years. Flammability test data obtained using Test 1 of NASA-STD-6001 is a significant component of this database. NASA-STD-6001 recommends that Kydex 100 be used as a reference material for testing certification and for comparison between test facilities in the round-robin certification testing that occurs every 2 years. As a result of these regular activities, a large volume of test data is recorded within the MAPTIS database. The activity described in this technical report was undertaken to mine the database, recover flammability (Test 1) Kydex 100 data, and review the lessons learned from analysis of these data.

Engel, Carl D.↗
NASA NTRS2004

A New Test Method for Material Flammability Assessment in Microgravity and Extraterrestrial Environments

The standard oxygen consumption (cone) calorimeter (described in ASTM E 1354 and NASA STD 6001 Test 2) is modified to provide a bench-scale test environment that simulates the low velocity buoyant or ventilation flow generated by or around a burning surface in a spacecraft or extraterrestrial gravity level. The Equivalent Low Stretch Apparatus (ELSA) uses an inverted cone geometry with the sample burning in a ceiling fire (stagnation flow) configuration. For a fixed radiant flux, ignition delay times for characterization material PMMA are shown to decrease by a factor of three at low stretch, demonstrating that ignition delay times determined from normal cone tests significantly underestimate the risk in microgravity. The critical heat flux for ignition is found to be lowered at low stretch as the convective cooling is reduced. At the limit of no stretch, any heat flux that exceeds the surface radiative loss at the surface ignition temperature is sufficient for ignition. Regression rates for PMMA increase with heat flux and stretch rate, but regression rates are much more sensitive to heat flux at the low stretch rates, where a modest increase in heat flux of 25 kW/m2 increases the burning rates by an order of magnitude. The global equivalence ratio of these flames is very fuel rich, and the quantity of CO produced in this configuration is significantly higher than standard cone tests. These results [2] demonstrate the ELSA apparatus allows us to conduct normal gravity experiments that accurately and quantifiably evaluate a material s flammability characteristics in the real-use environment of spacecraft or extra-terrestrial gravitational acceleration. These results also demonstrate that current NASA STD 6001 Test 2 (standard cone) is not conservative since it evaluates materials flammability with a much higher inherent buoyant convective flow.

Olson, S. L.↗
NASA NTRS2005

Promoted Metals Combustion at Ambient and Elevated Temperatures

Promoted combustion testing of materials, Test 17 of NASA STD-6001, has been used to assess metal propensity to burn in oxygen rich environments. An igniter is used at the bottom end of a rod to promote ignition, and if combustion is sustained, the burning progresses from the bottom to the top of the rod. The physical mechanisms are very similar to the upward flammability test, Test 1 of NASA STD-6001. The differences are in the normal environmental range of pressures, oxygen content, and sample geometry. Upward flammability testing of organic materials can exhibit a significant transitional region between no burning to complete quasi-state burning. In this transitional region, the burn process exhibits a probabilistic nature. This transitional region has been identified for metals using the promoted combustion testing method at ambient initial temperatures. The work given here is focused on examining the transitional region and the quasi-steady burning region both at conventional ambient testing conditions and at elevated temperatures. A new heated promoted combustion facility and equipment at Marshall Space Flight Center have just been completed to provide the basic data regarding the metals operating temperature limits in contact with oxygen rich atmospheres at high pressures. Initial data have been obtained for Stainless Steel 304L, Stainless Steel 321, Haynes 214, and Inconel 718 at elevated temperatures in 100-percent oxygen atmospheres. These data along with an extended data set at ambient initial temperature test conditions are examined. The pressure boundaries of acceptable, non-burning usage is found to be lowered at elevated temperature.

Engel, Carl D.↗
NASA NTRS2006

Structural Requirements for the Space Propulsion Engine Systems

In January 2004, the National Aeronautics and Space Administration (NASA) was given a vision for Space Exploration by President Bush, setting our sight on a bold new path to go back to the Moon, then to Mars and beyond. As NASA gets ready to meet the vision set by President Bush, failures are not an option. Reliability of the propulsion engine systems will play an important role in establishing an overall safe and reliable operation of these new space systems. A new standard, NASA-STD-5012, Strength and Life Assessment for Space Propulsion System Engines, has been developed to provide structural requirements for assessment of the propulsion systems engine. This standard is a complement to the current NASA-wide standard NASA-STD-5001, Structural Design and Test Factors of Safety for Spaceflight Hardware, which excluded the requirement for the engine systems (rotatory structures) along with pressure vessels. As developed, this document builds on the heritage of the multiple industrial standards related to strength and life assessment of the structures. For assuring a safe and reliable operation of a product and/or mission, establishing a set of structural assessment requirements is a key ingredient. Hence, a concentrated effort was made to improve the requirements where there are known lessons learned during the design, test, and operation phases of the Space Shuttle Main Engine (SSME) and other engine development programs. Requirements delineated in this standard are also applicable for the reusable and/or human missions. It shall be noted that "reliability of a system cannot be tested and inspected but can only be achieved if it is first designed into a system." Hence, these strength and life assessment requirements for the space propulsion system engines shall be used along with other good engineering practices, requirements, and policies.

Aggarwal, Pravin K.↗
NASA NTRS2004

Alternative Test Methods for Electronic Parts

It is common practice within NASA to test electronic parts at the manufacturing lot level to demonstrate, statistically, that parts from the lot tested will not fail in service using generic application conditions. The test methods and the generic application conditions used have been developed over the years through cooperation between NASA, DoD, and industry in order to establish a common set of standard practices. These common practices, found in MIL-STD-883, MIL-STD-750, military part specifications, EEE-INST-002, and other guidelines are preferred because they are considered to be effective and repeatable and their results are usually straightforward to interpret. These practices can sometimes be unavailable to some NASA projects due to special application conditions that must be addressed, such as schedule constraints, cost constraints, logistical constraints, or advances in the technology that make the historical standards an inappropriate choice for establishing part performance and reliability. Alternate methods have begun to emerge and to be used by NASA programs to test parts individually or as part of a system, especially when standard lot tests cannot be applied. Four alternate screening methods will be discussed in this paper: Highly accelerated life test (HALT), forward voltage drop tests for evaluating wire-bond integrity, burn-in options during or after highly accelerated stress test (HAST), and board-level qualification.

Plante, Jeannette↗
NASA NTRS2007

NASA Space Flight Human System Standards

NASA has begun a new approach to human factors design standards. For years NASA-STD-3000, Manned Systems Integration Standards, has been a source of human factors design guidance for space systems. In order to better meet the needs of the system developers, NASA is revising its human factors standards system. NASA-STD-3000 will be replaced by two documents: set of broad human systems specifications (including both human factors and medical topics) and a human factors design handbook

Tillman, Barry↗
NASA NTRS2007

Revitalization of Space-Related Human Factors, Environmental and Habitability Data

The NASA Chief Health and Medical Officer (CHMO) recently directed that the agency establish crew health standards to aid in the development of requirements for future vehicles and habitats. Response to this direction includes development of a new NASA habitability and human factors standard and an accompanying design handbook. The new standard contains high-level, over-arching principles to assure its applicability and usability across all NASA development programs. The handbook will provide detailed design requirements and suggestions that will meet the standards. The information contained in NASA-STD-3000 will be updated and included in the new design handbook. In this approach, each new program will derive detailed program-specific requirements from the new standard using the handbook as a design guide and resource. With the completion of the standard, the focus of this year s effort is the development of the new handbook: Human Integration Design Handbook (HIDH). This is an opportunity for the space flight human factors and habitability community to consolidate up-to-date data for use by NASA programs and designers as well as outside researchers and policy makers looking for the next research focus. The goal of the handbook is to help NASA design and build human space flight systems which accommodate the capabilities and limitations of the crew so as to provide an environment where the crew can live and work effectively, safely, and comfortably. Handbook contents will address that primary goal, addressing unique aspects of space flight and habitation, including reduced gravity conditions, time lags, EVA systems and day/night cycles, not addressed in other standards or handbooks. The handbook will be divided into topics similar to NASA-STD-3000 (anthropometrics, architecture, workstations, etc.) and each topic area will contain elements for designers, human factors practitioners, program managers, operators, and researchers. The handbook will include the following elements: (1) Design considerations include a clear and concise summary of what is important to designers in space vehicle / habitat design, design information to translate Earth-base knowledge to the space environment, space issues and the data necessary to address those issues, and a consistent set of terminology. (2) Updates to Lessons Learned and example solutions from Shuttle and Station program experience will provide historical examples to help prevent repeating mistakes or reinvention of the wheel. (3) Requirements will aid in the translation of standards into program specific requirements. The scope of included requirements will define the pool that each program needs to consider and tailor for their specific program. (4) Requirements rationale will help understanding of the importance of these considerations. The HIDH development team at JSC is finalizing the format of the new handbook, prioritizing topic areas for expansion and update, and contacting subject matter experts within the scientific community to assist with this effort. Plans are also being made to continue handbook expansion and maintenance to assure it remains a valuable resource for human factors and human space flight programs.

Russo, Dane↗
NASA NTRS2008

Human Factors Engineering Standards at NASA

NASA has begun a new approach to human factors design standards. For years NASA-STD-3000, Manned Systems Integration Standards, has been a source of human factors design guidance for space systems. In order to better meet the needs of the system developers, NASA is revising its human factors standards system. NASA-STD-3000 will be replaced by two documents: set of broad human systems design standards (including both human factors and medical topics) and a human factors design handbook. At the present time the standards document is in final review with some disagreement on several critical issues. The handbook is progressing with November 2008 as the anticipated completion date.

Russo, Dane↗
NASA NTRS2008

Effect of Liquid Penetrant Sensitivity on Probability of Detection

The objective of the task is to investigate the effect of liquid penetrant sensitivity level on probability of crack detection (POD). NASA-STD-5009 currently requires the use of only sensitivity level 4 liquid penetrants. This requirement is based on the fact that the data generated in the NTIAC Nondestructive Evaluation (NDE) Capabilities Data Book was produced using only sensitivity level 4 penetrants. Many NDE contractors supporting NASA Centers routinely use sensitivity level 3 penetrants. Because of the new NASA-STD-5009 requirement, these contractors will have to either shift to sensitivity level 4 penetrants or perform formal POD demonstration tests to qualify their existing process.

Parker, Bradford H.↗
NASA NTRS2009

Quantifying Parameter Sensitivity, Interaction and Transferability in Hydrologically Enhanced Versions of Noah-LSM over Transition Zones

We use sensitivity analysis to identify the parameters that are most responsible for shaping land surface model (LSM) simulations and to understand the complex interactions in three versions of the Noah LSM: the standard version (STD), a version enhanced with a simple groundwater module (GW), and version augmented by a dynamic phenology module (DV). We use warm season, high-frequency, near-surface states and turbulent fluxes collected over nine sites in the US Southern Great Plains. We quantify changes in the pattern of sensitive parameters, the amount and nature of the interaction between parameters, and the covariance structure of the distribution of behavioral parameter sets. Using Sobol s total and first-order sensitivity indexes, we show that very few parameters directly control the variance of the model output. Significant parameter interaction occurs so that not only the optimal parameter values differ between models, but the relationships between parameters change. GW decreases parameter interaction and appears to improve model realism, especially at wetter sites. DV increases parameter interaction and decreases identifiability, implying it is overparameterized and/or underconstrained. A case study at a wet site shows GW has two functional modes: one that mimics STD and a second in which GW improves model function by decoupling direct evaporation and baseflow. Unsupervised classification of the posterior distributions of behavioral parameter sets cannot group similar sites based solely on soil or vegetation type, helping to explain why transferability between sites and models is not straightforward. This evidence suggests a priori assignment of parameters should also consider climatic differences.

Rosero, Enrique↗
NASA NTRS2009

Spaceflight Human System Standards

NASA created a new approach for human system integration and human performance standards. NASA created two documents a standard and a reference handbook. The standard is titled NASA Space Flight Human-System Standard (SFHSS) and consists of two-volumes: Volume 1- Crew Health This volume covers standards needed to support astronaut health (medical care, nutrition, sleep, exercise, etc.) Volume 2 Human Factors, Habitability and Environmental Health This volume covers the standards for system design that will maintain astronaut performance (ie., environmental factors, design of facilities, layout of workstations, and lighting requirements). It includes classic human factors requirements. The new standards document is written in terms so that it is applicable to a broad range of present and future NASA systems. The document states that all new programs prepare system-specific requirements that will meet the general standards. For example, the new standard does not specify a design should accommodate specific percentiles of a defined population. Rather, NASA-STD-3001, Volume 2 states that all programs shall prepare program-specific requirements that define the user population and their size ranges. The design shall then accommodate the full size range of those users. The companion reference handbook, Human Integration Design Handbook (HIDH), was developed to capture the design consideration information from NASA-STD-3000, and adds spaceflight lessons learned, gaps in knowledge, example solutions, and suggests research to further mature specific disciplines. The HIDH serves two major purposes: HIDH is the reference document for writing human factors requirements for specific systems. HIDH contains design guidance information that helps insure that designers create systems which safely and effectively accommodate the capabilities and limitations of space flight crews.

Holubec, Keith↗