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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

The JPL Molecular Contamination Investigation Facility

The Molecular Contamination Investigation Facility (MCIF) is discussed in terms of its use for improving the far-UV performance of a camera and its broader applications. The MCIF incorporates two independent vacuum systems with sample isolation chambers and regulated heat exchangers as well as three quartz-crystal microbalances (QCMs) and a residual gas analyzer. One cryogenic QCM is heat sunk into an LN2 heat exchanger, while the others are thermoelectrically controlled and are heat sunk into a regulated heat exchanger. Outgas accumulation can be measured at three surface temperatures between -180 and 80 C simultaneously, and results are presented for the testing of 34 samples in a large-chambered system and 22 samples in a system with a smaller chamber. The MCIF results provide a database for fabrication processes, material selection, maximum bakeout temperatures, and the development of an ultraclean bakeout chamber.

Taylor, Daniel M.↗
NASA NTRS1991

Satellite orbit considerations for a global change technology architecture trade study

A study was conducted to determine satellite orbits for Earth observation missions aimed at obtaining data for assessing global climate change. A multisatellite system is required to meet the scientific requirements for temporal coverage over the globe. The best system consists of four Sun-synchronous satellites equally spaced in local time of equatorial crossing. This system can obtain data every three hours for all regions. Several other satellite systems consisting of combinations of Sun-synchronous orbits and either the Space Station Freedom or a mid-latitude equatorial satellite can provide three to six hour temporal coverage, which is sufficient for measuring many of the parameters required for the global change monitoring mission. Geosynchronous satellites are required to study atmospheric and surface processes involving variations on the order of a few minutes to an hour. Two or more geosynchronous satellites can be relocated in longitude to study processes over selected regions of Earth.

Harrison, Edwin F.↗
NASA NTRS1992

Trend analysis for large solid rocket motors - A program level approach

This paper defines a program-level trend analysis effort that can be applied to large solid rocket motors. The effort is especially applicable to large segmented rocket motors such as the Space Transportation System's solid rocket boosters. Five types of trend analysis are discussed for different aspects of a rocket motor program, (performance, reliability, problem, supportability, and programmatic). Ideas are offered for implementing and performing a program-level trend analysis effort by giving suggestions for selecting computer capabilities, choosing parameters, selecting statistical processes, routine screening for trends, analyzing significant trends (for example, looking for related trends and determining if adverse trends are resolved), and reporting results of trend analysis. The use of program-level trending allows for the ability to easily transfer data between organizations and easily use the data to correlate trends from the various organizations to find causal relationships. Efficiency is enhanced from upper level management to the shop floor at vendor locations by using the same trend analysis software and methodology at all organizations.

Babbitt, Norman E., III↗
NASA NTRS1993

Testing of ROMPS robot mechanical interfaces and compliant device

The Robot Operated Materials Processing System (ROMPS) has been developed at Goddard Space Flight Center (GSFC) under a flight project to investigate commercially promising in-space material processes and to design reflyable robot automated systems to be used in the above processes for low-cost operations. The ROMPS is currently scheduled for flight in 1994 as a Hitchhiker payload in a Get Away Special (GAS) can. An important component of the ROMPS is a three degree-of-freedom (DOF) robot which will be responsible for carrying out the required tasks of in-space processing of selected materials. This report deals with testing of the mating capability of the ROMPS robot fingers with its various mechanical interfaces. In particular, the test plan will focus on studying the capability of a compliance mechanism mounted on the robot fingers in accommodating misalignments between the robot fingers and the interfaces during the mating. The report is organized as follows: Section 2 represents the main components of the ROMPS robot and briefly describes its operations. Section 3 presents the objectives of the test and outlines the test plan. The testbed comprising a Steward Platform-based high precision manipulator and associated data acquisition and control systems is described in Section 4. Section 5 presents results of numerous experiments conducted to study the mating capability of the robot fingers with its various interfaces under misalignments. The report is concluded with observations and recommendations based on the test results.

Nguyen, Charles C.↗
NASA NTRS1993

Solving modal equations of motion with initial conditions using MSC/NASTRAN DMAP. Part 1: Implementing exact mode superposition

Within the MSC/NASTRAN DMAP (Direct Matrix Abstraction Program) module TRD1, solving physical (coupled) or modal (uncoupled) transient equations of motion is performed using the Newmark-Beta or mode superposition algorithms, respectively. For equations of motion with initial conditions, only the Newmark-Beta integration routine has been available in MSC/NASTRAN solution sequences for solving physical systems and in custom DMAP sequences or alters for solving modal systems. In some cases, one difficulty with using the Newmark-Beta method is that the process of selecting suitable integration time steps for obtaining acceptable results is lengthy. In addition, when very small step sizes are required, a large amount of time can be spent integrating the equations of motion. For certain aerospace applications, a significant time savings can be realized when the equations of motion are solved using an exact integration routine instead of the Newmark-Beta numerical algorithm. In order to solve modal equations of motion with initial conditions and take advantage of efficiencies gained when using uncoupled solution algorithms (like that within TRD1), an exact mode superposition method using MSC/NASTRAN DMAP has been developed and successfully implemented as an enhancement to an existing coupled loads methodology at the NASA Lewis Research Center.

Abdallah, Ayman A.↗
NASA NTRS1992

Space Station Furnace Facility. Volume 2: Summary of technical reports

The Space Station Furnace Facility (SSFF) is a modular facility for materials research in the microgravity environment of the Space Station Freedom (SSF). The SSFF is designed for crystal growth and solidification research in the fields of electronic and photonic materials, metals and alloys, and glasses and ceramics, and will allow for experimental determination of the role of gravitational forces in the solidification process. The facility will provide a capability for basic scientific research and will evaluate the commercial viability of low-gravity processing of selected technologically important materials. In order to accommodate the furnace modules with the resources required to operate, SSFF developed a design that meets the needs of the wide range of furnaces that are planned for the SSFF. The system design is divided into subsystems which provide the functions of interfacing to the SSF services, conditioning and control for furnace module use, providing the controlled services to the furnace modules, and interfacing to and acquiring data from the furnace modules. The subsystems, described in detail, are as follows: Power Conditioning and Distribution Subsystem; Data Management Subsystem; Software; Gas Distribution Subsystem; Thermal Control Subsystem; and Mechanical Structures Subsystem.

Source record↗
NASA NTRS1993

Planning collision free paths for two cooperating robots using a divide-and-conquer C-space traversal heuristic

A method was developed to plan feasible and obstacle-avoiding paths for two spatial robots working cooperatively in a known static environment. Cooperating spatial robots as referred to herein are robots which work in 6D task space while simultaneously grasping and manipulating a common, rigid payload. The approach is configuration space (c-space) based and performs selective rather than exhaustive c-space mapping. No expensive precomputations are required. A novel, divide-and-conquer type of heuristic is used to guide the selective mapping process. The heuristic does not involve any robot, environment, or task specific assumptions. A technique was also developed which enables solution of the cooperating redundant robot path planning problem without requiring the use of inverse kinematics for a redundant robot. The path planning strategy involves first attempting to traverse along the configuration space vector from the start point towards the goal point. If an unsafe region is encountered, an intermediate via point is identified by conducting a systematic search in the hyperplane orthogonal to and bisecting the unsafe region of the vector. This process is repeatedly applied until a solution to the global path planning problem is obtained. The basic concept behind this strategy is that better local decisions at the beginning of the trouble region may be made if a possible way around the 'center' of the trouble region is known. Thus, rather than attempting paths which look promising locally (at the beginning of a trouble region) but which may not yield overall results, the heuristic attempts local strategies that appear promising for circumventing the unsafe region.

Weaver, Johnathan M.↗
NASA NTRS1985

Carbon and nitrogen biogeochemistry in the ocean: A study using stable isotope natural abundance

Determining the biogeochemical pathways traveled by carbon and nitrogen in the ocean is fundamental to the understanding of how the ocean participates in the cycling of these elements within the biosphere. Because biological production, metabolism, and respiration can significantly alter the natural abundance of C-13 and N-15, these abundances can provide important information about the nature of these biological processes and their variability in the marine environment. The research initially seeks to characterize the spatial and temporal patterns of stable isotope abundances in organic matter, and to relate these abundances to C and N biogeochemical processes within selected areas of the northeastern Pacific Ocean.

Rau, G. H.↗
NASA NTRS1993

The GAMCIT gamma ray burst detector

The GAMCIT payload is a Get-Away-Special payload designed to search for high-energy gamma-ray bursts and any associated optical transients. This paper presents details on the design of the GAMCIT payload, in the areas of battery selection, power processing, electronics design, gamma-ray detection systems, and the optical imaging of the transients. The paper discusses the progress of the construction, testing, and specific design details of the payload. In addition, this paper discusses the unique challenges involved in bringing this payload to completion, as the project has been designed, constructed, and managed entirely by undergraduate students. Our experience will certainly be valuable to other student groups interested in taking on a challenging project such as a Get-Away-Special payload.

Mccall, Benjamin J.↗
NASA NTRS1994

Composite hot drape forming

This program was initiated to replace labor-intensive ply-by-ply layup of composite I-beam posts and angle stiffeners used in the Space Station Freedom (SSF) rack structure. Hot drape forming (HDF) has been successfully implemented by BCAG for 777 composite I-stringers and by Bell Helicopter/Textron for the V-22 I-stingers. The two companies utilize two vastly different approaches to the I-beam fabrication process. A drape down process is used by Bell Helicopter where the compacted ply charge is placed on top of a forming mandrel and heated. When the heated ply charge reached a set temperature, vacuum pressure is applied and the plies are formed over the mandrel. The BCAG 777 process utilizes an inverted forming process where the ply stack is placed on a forming table and the mandrel is inverted and placed upon the ply stack. A heating and vacuum bladder underneath the ply stack form the play stack up onto the mandrels after reaching the temperature setpoint. Both methods have their advantages, but the drape down process was selected for SSF because it was more versatile and could be fabricated from readily available components.

Ott, Thomas↗
NASA NTRS1995

Information Switching Processor (ISP) contention analysis and control

In designing a satellite system with on-board processing, the selection of a switching architecture is often critical. The on-board switching function can be implemented by circuit switching or packet switching. Destination-directed packet switching has several attractive features, such as self-routing without on-board switch reconfiguration, no switch control memory requirement, efficient bandwidth utilization for packet switched traffic, and accommodation of circuit switched traffic. Destination-directed packet switching, however, has two potential concerns: (1) contention and (2) congestion. And this report specifically deals with the first problem. It includes a description and analysis of various self-routing switch structures, the nature of contention problems, and contention and resolution techniques.

Inukai, Thomas↗
NASA NTRS1997

Method for Reducing Pumping Damage to Blood

Methods are provided for minimizing damage to blood in a blood pump wherein the blood pump comprises a plurality of pump components that may affect blood damage such as clearance between pump blades and housing, number of impeller blades, rounded or flat blade edges, variations in entrance angles of blades, impeller length, and the like. The process comprises selecting a plurality of pump components believed to affect blood damage such as those listed herein before. Construction variations for each of the plurality of pump components are then selected. The pump components and variations are preferably listed in a matrix for easy visual comparison of test results. Blood is circulated through a pump configuration to test each variation of each pump component. After each test, total blood damage is determined for the blood pump. Preferably each pump component variation is tested at least three times to provide statistical results and check consistency of results. The least hemolytic variation for each pump component is preferably selected as an optimized component. If no statistical difference as to blood damage is produced for a variation of a pump component, then the variation that provides preferred hydrodynamic performance is selected. To compare the variation of pump components such as impeller and stator blade geometries, the preferred embodiment of the invention uses a stereolithography technique for realizing complex shapes within a short time period.

Bozeman, Richard J., Jr.↗
NASA NTRS1997

Finite Element Analysis of Magnetic Damping Effects on G-Jitter Induced Fluid Flow

This paper reports some interim results on numerical modeling and analyses of magnetic damping of g-jitter driven fluid flow in microgravity. A finite element model is developed to represent the fluid flow, thermal and solute transport phenomena in a 2-D cavity under g-jitter conditions with and without an applied magnetic field. The numerical model is checked by comparing with analytical solutions obtained for a simple parallel plate channel flow driven by g-jitter in a transverse magnetic field. The model is then applied to study the effect of steady state g-jitter induced oscillation and on the solute redistribution in the liquid that bears direct relevance to the Bridgman-Stockbarger single crystal growth processes. A selection of computed results is presented and the results indicate that an applied magnetic field can effectively damp the velocity caused by g-jitter and help to reduce the time variation of solute redistribution.

Pan, Bo↗
NASA NTRS2000

Low-Cost Approach to the Design and Fabrication of a LOX/RP-1 Injector

NASA Marshall Space Flight Center (MSFC) has designed, built, and is currently testing Fastrac, a liquid oxygen (LOX)/RP-1 fueled 60K-lb thrust class rocket engine. One facet of Fastrac, which makes it unique is that it is the first large-scale engine designed and developed in accordance with the Agency's mandated "faster, better, cheaper" (FBC) program policy. The engine was developed under the auspices of MSFC's Low Cost Boost Technology office. Development work for the main injector actually began in 1993 in subscale form. In 1996, work began on the full-scale unit approximately 1 year prior to initiation of the engine development program. In order to achieve the value goals established by the FBC policy, a review of traditional design practices was necessary. This internal reevaluation would ultimately challenge more conventional methods of material selection. design process, and fabrication techniques. The effort was highly successful. This "new way" of thinking has resulted in an innovative injector design, one with reduced complexity and significantly lower cost. Application of lessons learned during this effort to new or existing designs can have a similar effect on costs and future program successes.

Shadoan, Michael D.↗
NASA NTRS2001

Superconducting Nb DHEB Mixer Arrays for Far-Infrared Spectroscopy

We are developing a heterodyne focal plane array with up to eight elements to study lines of the interstellar medium and planetary atmospheres with frequencies of 2 THz and above. Our fabrication process utilizes selective ion milling techniques to produce Nb Diffusion-Cooled Hot Electron Bolometric (DHEB) mixers from a bilayer thin film of Au/Nb deposited on a silicon substrate. A micro-bridge of 10 nm thick Nb forms the HEB device. The first generation of devices with lateral dimensions of 100 nm by 80 nm were fabricated at the feed of a broadband spiral antenna with a frequency response designed for up to 16 THz. Harmonic multiplier sources becoming available within the next few years should have sufficient power to provide a local-oscillator source for small-format, quasi-optically coupled arrays of these mixers. First generation devices measured at our laboratory have demonstrated a critical temperature (Tc) of 4.8 K with a 0.5 K transition width. These DHEB mixers are expected to have an optimum operational temperature of 1.8-2.0 K. The current four element array mixer block will ultimately be replaced by a dual polarization slot-ring array configuration with up to eight elements.

Gerecht, E.↗
NASA NTRS2002

Regulatory and Technical Issues Concerning the Detection and Treatment of NDMA-Contaminated Groundwater at NASA WSTF

The National Aeronautics and Space Administration (NASA) White Sands Test Facility (WSTF) was established in 1963 primarily to provide rocket engine testing services for several NASA programs. The groundwater underlying the site has been contaminated as a result of historical operations. Groundwater contaminants include several volatile organic compounds (VOCs) and two semi-volatile compounds: N-nitrosodimethylamine (NDMA) and N-nitrodimethylamine (DMN). This paper discusses some of the technical, analytical, regulatory, and health risk issues associated with the contaminant plume. The plume has moved approximately 2.5 miles downgradient of the facility industrial boundary, with evidence of continued migration. As a result, NASA has proposed a pump and treat system using air strippers and ultraviolet (UV) oxidation to stabilize future movement of the contaminant plume. The system has been designed to treat 1,076 gallons (4,073 liters) per minute, with provisions for future expansion. The UV oxidation process was selected to treat NDMA-contaminated groundwater based on successes at other NDMA-contaminated sites. Bench- and pilot-scale testing of WSTF groundwater confirmed the ability of UV oxidation to destroy NDMA and generated sufficient data to design the proposed full-scale treatment system. NDMA is acutely toxic and is a probable human carcinogen. EPA-recommended health risk criteria for the residential consumption of NDMA/DMN-contaminated groundwater was used to determine that a 1.0 x 10(exp -6) excess cancer risk corresponds to 1.7 parts per trillion (ppt). EPA analytical methods are unable to detect NDMA and DMN in the low ppt range. EPA's current Appendix IX analytical method used to screen for NDMA, Method 8270, can detect NDMA only at levels that are orders of magnitude greater than the recommended health risk level. Additionally, EPA Method 607, the most sensitive EPA approved method, has a detection limit of 150 ppt. This corresponds to an excess cancer risk of 9.0 x 10(exp -5), which exceeds the State of New Mexico's water quality standard of a cancer risk less than 1 x 10(exp -5). The treatment system has been engineered to treat contaminated groundwater to levels significantly below the New Mexico standard. However, the inability of EPA-approved analytical methods to detect NDMA and DMN at low ppt levels, and to provide verification of compliance with the 1 x 10(exp -5) cancer risk, introduces a notable risk to the long-term operation of the system. WSTF has been working with Southwest Research Institute to develop a non-EPA analytical method that can achieve a reporting limit of 1 ppt, which corresponds to an excess cancer risk of 7.6 x 10(exp -7). WSTF is currently developing a proposal to obtain approval from the New Mexico Environment Department (NMED) of this non-EPA method.

Wiebe, D. T.↗
NASA NTRS2002

NASA's Laboratory Astrophysics Workshop: Opening Remarks

The Astronomy and Physics Division at NASA Headquarters has an active and vibrant program in Laboratory Astrophysics. The objective of the program is to provide the spectroscopic data required by observers to analyze data from NASA space astronomy missions. The program also supports theoretical investigations to provide those spectroscopic parameters that cannot be obtained in the laboratory; simulate space environment to understand formation of certain molecules, dust grains and ices; and production of critically compiled databases of spectroscopic parameters. NASA annually solicits proposals, and utilizes the peer review process to select meritorious investigations for funding. As the mission of NASA evolves, new missions are launched, and old ones are terminated, the Laboratory Astrophysics program needs to evolve accordingly. Consequently, it is advantageous for NASA and the astronomical community to periodically conduct a dialog to assess the status of the program. This Workshop provides a forum for producers and users of laboratory data to get together and understand each others needs and limitations. A multi-wavelength approach enables a cross fertilization of ideas across wavelength bands.

Hasan, Hashima↗
NASA NTRS2003

Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg-0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300F for 24hours. In this study, a two-step aging treatment was developed through a comprehensive 2(exp 4) full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175F and 250F. The second step aging temperatures was varied between 275F and 325F, which is in the range of the single-step aging temperature. The results of the design of experiments used for the T8 temper as well as a smaller set of experiments for the T6 temper will be presented. The process of selecting the optimum aging treatment, based on the measured mechanical properties at room and cryogenic temperature as well as the observed deformation mechanisms, will be presented in detail. The implications for the use of alloy C458 in cryotanks will be discussed.

Sova, B. J.↗