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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Tether Transport System Study Summary Performed under Contract to Marshall Space Flight Center

The main rationale for this study is to reduce the mission cost of transporting payloads to GEO. A two stage tether transport system was proposed for boosting payloads from LEO to GTO/GEO. The feasibility of the concept is addressed from the point of view of orbital mechanics and other principles of physics. The report presents the results of an engineering analysis that defines the system, major elements and subsystems, and assesses the feasibility (i.e., the technology readiness level) of designing and developing the system. Results indicate that significant cost savings can be realized over traditional upper stages within a few launches. Certain key technical issues, such as payload rendezvous and capture, need to be addressed in future studies. Advancements in certain technology areas, such as power generation and highly efficient propulsion systems, will have significant effects on the overall system design.

Vonderwell, Dan↗
NASA NTRS1998

An Integrated Approach to Engineering Education in a Minority Community

Northeastern New Mexico epitomizes regions which are economically depressed, rural, and predominantly Hispanic. New Mexico Highlands University (NMHU), with a small student population of approximately 2800, offers a familiar environment attracting students who might otherwise not attend college. An outreach computer network of minority schools was created in northeastern New Mexico with NASA funding. Rural and urban minority schools gained electronic access to each other, to computer resources, to technical help at New Mexico Highlands University and gained access to the world via the Internet. This outreach program was initiated in the fall of 1992 in an effort to attract and to involve minority students in Engineering and the Mathematical Sciences. We installed 56 Kbs Internet connections to eight elementary schools, two middle schools, two high schools, a public library (servicing the home schooling community) and an International Baccalaureate school. For another fourteen rural schools, we provided computers and free dial-up service to servers on the New Mexico Highlands University campus.

Taylor, Bill↗
NASA NTRS1998

Lunar and Solar Torques on the Oceanic Tides

A general framework for calculating lunar and solar torques on the oceanic tides is developed in terms of harmonic constituents. Axial torques and their associated angular momentum and earth-rotation variations are deduced from recent satellite-altimeter and satellite-tracking tide solutions. Torques on the prograde components of the tide produce the familiar secular braking of the rotation rate. The estimated secular acceleration is approximately -1300 sec/century(sup 2) (less 4% after including atmospheric tides); the implied rate of change in the length of day is 2.28 milliseconds/century. Torques on the retrograde components of the tide produce periodic rotation variations at twice the tidal frequency. Interaction torques, e.g. solar torques on lunar tides, generate a large suite of rotation-rate variations at sums and differences of the original tidal frequencies. These are estimated for periods from 18.6 years to quarter-diurnal. At subdaily periods the angular momentum variations are 5 to 6 orders of magnitude smaller than the variations caused by ocean tidal currents.

Ray, Richard D.↗
NASA NTRS1998

Transportation: Destination Mars

As the agency space transportation lead center, Marshall Space Flight Center has been conducting transportation assessments for future robotic and human Mars missions to identify critical technologies. Five human Mars options are currently under assessment with each option including all transportation requirements from Earth to Mars and return. The primary difference for each option is the propulsion source from Earth to Mars. In case any of the options require heavy launch capability that is not currently projected as available, an in-house study has been initiated to determine the most cost effective means of providing such launch capability. This assessment is only considering launch architectures that support the overall human Mars mission cost goal of $25B. The guidelines for the launch capability study included delivery of 80 metric ton (176 KLB) payloads, 25 feet diameter x 92 feet long, to 220 nmi orbits at 28.5 degrees. The launch vehicle concept of the study was designated "Magnum" to differentiate from prior heavy launch vehicle assessments. This assessment along with the assessment of options for all transportation phases of a Mars mission are on-going.

Eoff, Bill↗
NASA NTRS1998

Utility of Lava Tubes on Other Worlds

On Mars, as on Earth, lava tubes are found in the extensive lava fields associated with shield volcanism. Lunar lava-tube traces are located near mare-highland boundaries, giving access to a variety of minerals and other resources, including steep slopes, prominent heights for local area communications and observation, large-surface areas in shade, and abundant basalt plains suitable for landing sites, mass-drivers, surface transportation, regolith harvesting, and other uses. Methods for detecting lava tubes include visual observations of collapse trenches and skylights, ground-penetrating radar, gravimetry, magnetometry, seismography, atmospheric effects, laser, lidar, infrared, and human or robotic exploration.

Walden, Bryce E.↗
NASA NTRS1998

Climate-Rotation Feedback on Mars

It has long been understood that changes in the orbital and rotational geometry of Mars will influence the seasonal and latitudinal pattern of insolation, and this will likely dominate climatic fluctuations on timescales of 105 to 107 yr [6-91. Equally important, but less widely appreciated, is the influence climatic change can have on rotational dynamics. The primary means by which climate influences rotation is via its influence on transport of mass (volatiles and dust) into and out of the polar regions. Both the rate and direction of Mars rotation can be changed by these mass fluxes, but only the directional changes are climatically relevant.

Bills, B. G.↗
NASA NTRS1997

Mars Dynamics from Earth-Based Tracking of the Mars Pathfinder Lander

Measurements of Mars' rotational variations can be conducted via Earth-based radio tracking observations of the Mars Pathfinder lander during an extended mission. Two-way range measurements between an Earth tracking station and the lander will enable precise monitoring of the planet's orientation, allowing details of Mars' internal structure and global surface/atmosphere interactions to be determined. An analysis has been performed to investigate the accuracy with which key physical parameters of Mars can be determined using the Earth-based radio tracking measurements. Acquisition of such measurements over one Martian year should enable determination of Mars' polar moment of inertia to 1% or better, providing a strong constraint on radial density profiles (and hence on the iron content of the core and mantle) and on long-term variations of the obliquity, which influences the climate. Variations in Mars length of day and polar motion should also be detectable, and will yield information on the seasonal cycling of carbon dioxide between the atmosphere and the surface.

Folkner, W. M.↗
NASA NTRS1999

Preliminary Findings: Issues in Surface Movement

The final report for the grant is presented. The recent goals for this project have been: (1) To identify common surface movement challenges which affect the airlines and Air Traffic Control; (2) To map out possible solutions to these challenges; (3) To start generalizing about the information we are receiving so that major, abstract categories of challenges and potential solutions will begin to emerge. In particular, there are several areas of opportunity which are beginning to emerge from the data, dealing with the need for: (1) Tools to support information exchange regarding priorities (both within an individual airline and between the ATC tower and airlines). Such priorities include both concerns affecting departure throughput as well as the ordering of departures to accommodate other airline considerations; (2) Planning tools to help ATC and airline Ramp staff deal with information about priorities; (3) Implementation of strategies to enable greater flexibility in queueing flights for departures; (4) Tools to provide better coordination and situation awareness during taxiing (within an airline as well as between airlines and between the airlines); (5) Tools to support planning and to deal with the interactions between departures and arrivals. Thus far, the initial interviews and observations at three airlines and two ATC facilities have been completed.

Smith, Philip J.↗
NASA NTRS1998

Effects of Convective Solute and Impurity Transport in Protein Crystal Growth

High-resolution optical interferometry was used to investigate the effects of forced solution convection on the crystal growth kinetics of the model protein lysozyme. Most experiments were conducted with 99.99% pure protein solutions. To study impurity effects, approx. 1% of lysozyme dimer (covalently bound) was added in some cases. We show that the unsteady kinetics, corresponding to bunching of growth steps, can be characterized by the Fourier components of time traces of the growth rate. Specific Fourier spectra are uniquely determined by the solution conditions (composition, temperature, and flow rate) and the growth layer source activity. We found that the average step velocity and growth rate increase by approx. I0% with increasing flow rate, as a result of the enhanced solute supply to the interface. More importantly, faster convective transport results in lower fluctuation amplitudes. This observation supports our rationale for system-dependent effects of transport on the structural perfection of protein crystals. We also found that solution flow rates greater than 500 microns/s result in stronger fluctuations while the average growth rate is decreased. This can lead to growth cessation at low supersaturations. With the intentionally contaminated solutions, these undesirable phenomena occurred at about half the flow rates required in pure solutions. Thus, we conclude that they are due to enhanced convective supply of impurities that are incorporated into the crystal during growth. Furthermore, we found that the impurity effects are reduced at higher crystal growth rates. Since the exposure time of terraces is inversely proportional to the growth rate, this observation suggests that the increased kinetics instability results from impurity adsorption on the interface. Finally, we provide evidence relating earlier observations of "slow protein crystal growth kinetics" to step bunch formation in response to nonsteady step generation.

Vekilov, Peter G.↗
NASA NTRS1996

Repartitioning of NaCl and Protein Impurities in Lysozyme Crystallization

Nonuniform precipitant and impurity incorporation in protein crystals can cause lattice strain and, thus, possibly decrease the X-ray diffraction resolution. To address this issue, a series of crystallization experiments were carried out, in which initial supersaturation, NaCl concentration, protein purity level and crystallized fraction were varied. Lysozyme and protein impurities, as well as sodium and chloride were independently determined in the initial solution, supernatant and crystals. The segregation coefficients for Na(+) and Cl(-) were found to be independent of supersaturation and NaCl concentration, and decreased with crystallized fraction/crystal size. Numerical evaluation of the extensive body of data, based on a nucleation-growth- repartitioning model, suggests a core of approx. 40 microns in which salt is incorporated in much greater concentrations than during later growth. Small crystals containing higher amounts of incorporated NaCl also had higher protein impurity contents. This suggests that the excess salt is associated with the protein impurities in the core. X-ray topography revealed strain fields in the center of the crystals comparable in size to the inferred core. The growth rates of crystals smaller than 30-40 pm in size were consistently 1.5-2 times lower than those of larger crystals, presumably due to higher chemical potentials in the core.

Vekilov, Peter G.↗
NASA NTRS1999

NASA/First Materials Science Research Rack (MSRR-1) Module Inserts Development for the International Space Station

The Material Science Research Rack 1 (MSRR-1) of the Material Science Research Facility (MSRF) contains an Experiment Module (EM) being developed collaboratively by NASA and the European Space Agency (ESA). This NASA/ESA EM will accommodate several different removable and replaceable Module Inserts (MIs) which are installed on orbit. Two of the NASA MIs being developed for specific material science investigations are described herein.

Crouch, Myscha↗
NASA NTRS1998

Lunar and Solar Torques on the Oceanic Tides

Brosche and Seiler recently suggested that direct lunar and solar tidal torques on the oceanic tides play a significant role in the earth's short-period angular momentum balance ("short-period" here meaning daily and sub-daily). We reexamine that suggestion here, concentrating on axial torques and hence on variations in rotation rate. Only those spherical harmonic components of the ocean tide having the same degree and order as the tidal potential induce nonzero torques. Prograde components (those moving in the same direction as the tide-generating body) produce the familiar secular braking of the earth's rotation. Retrograde components, however, produce rapid variations in UTI at twice the tidal frequency. There also exist interaction torques between tidal constituents, e.g. solar torques on lunar tides. They generate UTI variations at frequencies equal to the sums and differences of the original tidal frequencies. We give estimates of the torques and angular momentum variations for each of the important regimes, secular to quarter-diurnal. For the M(sub 2) potential acting on the M(sub 2) ocean tide, we find an associated angular momentum variation of amplitude 3 x 10(exp 19) N m. This is 5 to 6 orders of magnitude smaller than the angular momentum variations associated with tidal currents. We conclude that these torques do not play a significant role in the short-period angular momentum balance.

Ray, Richard D.↗
NASA NTRS1998

Climate Rotation Feedback on Mars

It has long been appreciated that changes in the orbital and rotational geometry of Mars will influence the seasonal and latitudinal pattern of insolation [1-5], and this will likely dominate climatic fluctuations on time scales of 101 to 107 years (6-9]. Equally important, but less widely appreciated, is the influence climatic change can have on rotational dynamics. The primary means by which climate influences rotation is via its influence on transport of mass (volatiles and dust) into and out of the polar regions. Both the rate and direction of Mars rotation can be changed by these mass fluxes, but only the directional changes are climatically relevant.

Bills, Bruce G.↗
NASA NTRS1999

Climate-Rotation Feedback on Mars

A new model is presented for the coupled evolution of climate and rotation, as applied to Mars. It has long been appreciated that changes in the orbital and rotational geometry of Mars will influence the seasonal and latitudinal pattern of insolation [1-5], and this will likely dominate climatic fluctuations on time scales of 10(exp 5) to 10(exp 7) years [6-9]. Equally important, but less widely appreciated, is the influence climatic change can have on rotational dynamics. The primary means by which climate influences rotation is via its influence on transport of mass (volatiles and dust) into and out of the polar regions. Many important issues remain unresolved: What are the ages of the polar caps? What climatic periods are recorded in the polar layered deposits? What is the long term obliquity history?

Bills, Bruce G.↗
NASA NTRS1999

The Rondonia Lightning Detection Network: Network Description, Science Objectives, Data Processing/Archival Methodology, and First Results

A four station Advanced Lightning Direction Finder (ALDF) network was recently established in the state of Rondonia in western Brazil through a collaboration of U.S. and Brazilian participants from NASA, INPE, INMET, and various universities. The network utilizes ALDF IMPACT (Improved Accuracy from Combined Technology) sensors to provide cloud-to-ground lightning observations (i.e., stroke/flash locations, signal amplitude, and polarity) using both time-of-arrival and magnetic direction finding techniques. The observations are collected, processed and archived at a central site in Brasilia and at the NASA/ Marshall Space Flight Center (MSFC) in Huntsville, Alabama. Initial, non-quality assured quick-look results are made available in near real-time over the internet. The network will remain deployed for several years to provide ground truth data for the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite which was launched in November 1997. The measurements will also be used to investigate the relationship between the electrical, microphysical and kinematic properties of tropical convection. In addition, the long-term observations from this network will contribute in establishing a regional lightning climatological data base, supplementing other data bases in Brazil that already exist or may soon be implemented. Analytic inversion algorithms developed at NASA/Marshall Space Flight Center (MSFC) are now being applied to the Rondonian ALDF lightning observations to obtain site error corrections and improved location retrievals. The processing methodology and the initial results from an analysis of the first 6 months of network operations will be presented.

Blakeslee, Rich↗
NASA NTRS2000

Insert Concepts for the Material Science Research Rack (MSRR-1) of the Material Science Research Facility (MSRF) on the International Space Station (ISS)

The Material Science Research Rack I (MSRR-1) of the Material Science Research Facility (MSRF) contains an Experiment Module (EM) being developed collaboratively by NASA and the European Space Agency (ESA). This NASA/ESA EM will accommodate several different removable and replaceable Module Inserts (MIs) which are installed on orbit NASA's planned inserts include the Quench Module Insert (QMI) and the Diffusion Module Insert (DMI). The QMI is a high-gradient Bridgman-type vacuum furnace with quench capabilities used for experiments on directional solidification of metal alloys. The DMI is a vacuum Bridgman-Stockbarger-type furnace for experiments on Fickian and Soret diffusion in liquids. This paper discusses specific design features and performance capabilities of each insert. The paper also presents current prototype QMI hardware analysis and testing activities and selected results.

Crouch, Myscha↗
NASA NTRS1999

Dynamic Ground Effects Simulation Using OVERFLOW-D

This presentation is broken into 5 logical sections. The Background Information section describes the technical issues being address by this study. The Approach section describes the organization of the contract effort which was laid out as the most effective means of quantifying, with validated methods, the magnitude of dynamic ground effects for the TCA (Technology Concept Aircraft) configuration. The Validation Case section describes the analysis of the XB-70 configuration in both static and dynamic ground effect, with comparisons to wind tunnel and flight test data. The TCA Analysis section then describes the application of the same codes and methodologies to the TCA in both static and dynamic ground effect. Comparisons are made between the static and dynamic, as well as to early static data from a recent wind tunnel test on the TCA configuration. Finally, the work to date is summarized and the future direction of this study is outlined.

Dwyer, Bill↗
NASA NTRS2000

Concept for Determining the Life of Ceramic Matrix Composites Using Nondestructive Characterization Techniques

Damping measurements have been taken on ceramic matrix composite (CMC) turbopump blisks in the as fabricated, post proof testing, and post turbopump testing conditions. These results indicate that damping is able to quantify fatigue of the CMC blisk. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction and how changes in damping and ultrasonic elastic modulus data have established the concept as a possibility.

Effinger, Michael↗