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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Semikinetic and generalized transport models of the polar and solar winds

In order to gain a better understanding of the relative merits of the transport and kinetic approaches to modeling thermal space plasmas, a comparison is presented of a transport (bi-Maxwellian-based 16-moment equations) and a semikinetic description of supersonic flow in the solar wind and also of both supersonic and subsonic flows in the polar wind for 'steady state' conditions. The study shows: remarkable agreement between the two models for supersonic collisionless flows, even for the higher-order moments; the inadequacy of the semikinetic approach for modeling subsonic flows; and the superiority of the 16-moment transport over the semikinetic approach for modeling the solar wind. Further evidence that the bi-Maxwellian-based transport equations are a useful tool for studying 'thermal' space plasmas that develop non-Maxwellian features is provided.

Demars, H. G.↗
NASA NTRS1992

Cargo transfer vehicle - An element of the National Launch System

The paper describes the cargo transport vehicle (CTV), a rendezvous- and capture-capable on-orbit maneuvering stage of the NASA/DOD National Launch System (NLS) developed for off-loading the Space Shuttle for cargo delivery to the Space Station Freedom. Special attention is given to the background of the NLS CTV technology, a typical Space Station delivery mission profile, the design features of the payload accommodation system, and the forward propulsion module. The feasibility of the CTV functioning as an upper stage, in addition to acting as an on-orbit maneuvering system, is being presently considered.

Buchanan, Harry↗
NASA NTRS1993

Narrow band imaging and long slit spectroscopy of UGC 5101

UGC 5101 (z = 0.04; D is approximately equal to 240 Mpc) is one of the so called Ultraluminous IRAS sources. Two important properties of the members of this group are their L(sub IR) is greater than or equal to 10(exp 12) solar luminosity, and their space density in the universe up to z is less than 0.1 is equal or even larger than the space density of the quasars. Further noteworthy features of the Ultraluminous IRAS sources are their being morphologically peculiar and the fact that they all seem to host active nuclei in their center. We have observed UGC 5101 in an effort to study the interplay between the gas ionized by the central active nucleus and that gas ionized by other processes which may hold important clues to the understanding of the entire picture of this object. In particular these other ionizing processes could well be massive stars formed recently after the galactic encounter and shocks possibly also related to the galaxy collision. The data that we discuss were obtained between Dec. 1989 and Jan. 1992 with the WHT 4.2 m telescope using the two-arm spectrograph ISIS. Several spectral frames were obtained at three different position angles: PA 84--along the tail of the galaxy; PA 32--along the dust lane; and PA 110. The blue spectra are centered on the H beta line, while the red spectra are centered on the H alpha line. In the configuration we used for the long slit spectra, the spectral scale was 0.74 A per pixel, and the spatial scale was .37 arcsec per pixel; we also observed the H alpha region with a spectral scale of .37 A per pixel, at position angle 84. The narrow band images were obtained at the auxiliary port of ISIS, with a scale of .2 arcsec per pixel, and were centered at the H alpha wavelength, and on the adjacent continuum. The H alpha images and the spectra support the following model. UGC 5101 hosts an active nucleus; the NLR extends up to about 1.5 kpc and shows a complex velocity field, superimposed on the rotation curve of the galaxy. Besides the NLR, in the H alpha image are visible tow bright cones that extend up to 3 kpc along PA 32. The long slit spectra at PA 32 show that the velocity field of the gas in these regions is peculiar, while the ionization structure of the gas is similar to that of the NLR.

Stanga, R. M.↗
NASA NTRS1992

Update on the advanced Stirling conversion system project for 25 kW dish Stirling applications

Technology development for Stirling convertors directed toward a dynamic power source for space applications is examined. The free-piston Stirling engine has the potential for both solar and nuclear space power applications. Two parallel design directions feature a solar receiver/liquid metal heat transport system, and a free-piston Stirling convertor which incorporates a linear alternator to directly provide the electrical output of about 25 kW to a utility grid. The Cummins Engine Company (CEC) free-piston Stirling convertor incorporates a linear alternator along with hydrodynamic gas bearings to provide noncontacting, wear-free support to the pistons. The Stirling Technology Company design incorporates linear alternator technology with flexures that provide noncontacting support while also supplying much of the spring stiffness needed to obtain proper resonance.

Shaltens, Richard K.↗
NASA NTRS1989

STS-27 Crew Presentation Clip

This video features scenes from this Department of Defense Space Shuttle Mission. Included are launch, landing, the crew playing weightless football and exercising, and food preparation on middeck.

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NASA NTRS1994

Interactive shape metamorphosis

A technique for controlled metamorphosis between surfaces in 3-space is described. Well-understood techniques to produce shape metamorphosis between models in a 2D parametric space is applied. The user selects morphable features interactively, and the morphing process executes in real time on a high-performance graphics multicomputer.

Chen, David T.↗
NASA NTRS1995

Time-distance helioseismology in the vicinity of sunspots

We use the ray description of acoustic-gravity modes to calculate time-distance diagrams for the quiet Sun and for regions in the vicinity of a sunspot with a monolithic flux-tube structure. Time-distance curves for the quiet Sun match the observations of Duvall et al. In the vicinity of a sunspot these quiet Sun curves split into a family of closely spaced curves. The structure of this bandlike feature is found to be sensitive to the sunspot model and can be a diagnostic of the subsurface geometry of the sunspot flux tube.

D'Silva, Sydney↗
NASA NTRS1996

SPACE: Enhancing Life on Earth. Proceedings Report

The proceedings of the 12th National Space Symposium on Enhancing Life on Earth is presented. Technological areas discussed include: Space applications and cooperation; Earth sensing, communication, and navigation applications; Global security interests in space; and International space station and space launch capabilities. An appendices that include featured speakers, program participants, and abbreviation & acronyms glossary is also attached.

Hobden, Alan↗
NASA NTRS1997

Long-Duration Space Flight

Session WA1 includes short reports concerning: (1) Medical and Physiological Studies During 438-Day Space Flights: (2) Human Performance During a 14 Month Space Mission: (3) Homeostasis in Long-Term Microgravity Conditions; (4) Strategy of Preservation of Health of Cosmonauts in Prolonged and Superprolonged Space Flights; (5) Rehabilitation of Cosmonauts Health Following Long-Term Space Missions; and (6) Perfect Cosmonauts: Some Features of Bio-Portrait.

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NASA NTRS1999

The Conductor-Dielectric Junctions in a Low Density Plasma

A conductor-dielectric junction exposed to the space environment is a frequent spacecraft design feature. Due to spacecraft charging and/or solar array operation, the conductor can acquire a high potential with respect to the surrounding plasma. If this potential is positive the insulators adjacent to exposed conductors can collect current as if they were conductors themselves. This phenomenon, called snapover, results in a substantial increase in current collection, and may even result in a glow discharge if the potential is high enough. If a conductor has a negative potential, arcing can occur at the site of a junction. Both of these phenomena negatively affect spacecraft operation. To prevent negative consequences, the physical mechanisms of snapover and arc inception require investigation. In this paper, results are presented of an experimental and theoretical study of snapover, glow discharge, and arc phenomena for different materials immersed in argon or xenon plasmas. The effect of snapover is investigated for several metal-dielectric junctions: copper-teflon, copper-Kapton, copper-glass, aluminum-teflon, aluminum-Kapton, steel-teflon, anodized aluminum with pinholes, and copper-ceramics. I-V curves are measured and snapover inception voltages, essential parameters (increase in current and collection area due to secondary electrons), and glow discharge inception thresholds are determined. Optical spectra are obtained for glow discharges in both argon and xenon plasmas. These spectra provide information regarding atomic species entrapped in the glow region. Some spectral lines can be used to estimate plasma parameters in the discharge area. A video-camera and linear array were used to confirm that snapover inception is accompanied by very low intensity visible light emission. This result seems to be important for the estimate of the light pollution around spacecraft. Optical spectra (wavelengths 380-650 nm) of arcs are also obtained on a negatively biased chromic acid anodized aluminum plate immersed in low density argon and xenon plasmas. Analysis of these spectra confirms our earlier findings that aluminum atoms are ejected from the arc site. Moreover, it is found that chromium atoms are also quite abundant in the arc plasma. It is believed that the latter results contribute considerably to the understanding of processes of plasma contamination caused by arcing.

Vayner, Boris↗
NASA NTRS1994

Hubble Space Telescope Briefing: HST Science Overview

This NASA Kennedy Space Center video release presents a broad overview of the science that is now possible as a result of the servicing of the Hubble Space Telescope (HST). Dr. Ed Weiler (HST Program Scientist, NASA Headquarters), Dr. Dave Leckrone (HST, Senior Project Scientist, Goddard Space Flight Center (GSFC)), Dr. John Trauger (Wide Field Planetary Camera 2 (WFPC2) Principal Investigator, Jet Propulsion Lab. (JPL)), Dr. Chris Burrows (WFPC2 Co-Investigator, Space Telescope Science Inst.(STSci)-European Space Agency (ESA), Jim Crocker ((Corrective Optics Space Telescope Axial Replacement) COSTAR Team Leader, STSci), Dr. Holland Ford (COSTAR Project Scientist, Johns Hopkins Univ., STSci), and Dr. Duccio Machetto (European Space Agency (ESA)) give brief presentations, which feature images of stars and galaxies taken from the ground, from WFPC1 (prior to the servicing mission), and from WFPC2 (after the servicing mission). The main theme of the discussions center around the spherical aberration that was found in the images prior to servicing and the corrected images seen without the aberration following servicing. A question and answer period rounds out the press conference, with questions posed from scientific journalists at GSFC and other NASA centers.

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NASA NTRS1999

ISS Operations for the Special Purpose Dexterous Manipulator (SPDM) Experiences from the Robotic Systems Evaluation Laboratory (RSEL)

The International Space Station (ISS) will present a new era of telerobotic operations on-orbit. Operating the Special Purpose Dexterous Manipulator (SPDM) in its tasks of maintaining the multitude of Space Station Orbital Replaceable Units (ORUs) creates numerous operational considerations not seen in the existing Shuttle Remote Manipulator System (SRMS) or the future Space Station Remote Manipulator System (SSRMS). The differences between the large arms and the dexterous arm greatly affect the interconnection of man, robot, and task. This paper presents some of the issues arising from this new breed of on-orbit robotics as garnered from over three years of ORU testing experience within the Robotic Systems Evaluation Laboratory (RSEL) at NASA Johnson Space Center. The effects of new robotic features on operations, the issues surrounding targets and visual cues, the differences in operating with Force Moment Accommodation (FMA), the effects of changes in task complexity and scale, the lack of supporting flight information, and the changes in procedures required by the dexterous task will be discussed.

Spinler, Anthony B.↗
NASA NTRS2002

Lightning Return-Stroke Current Waveforms Aloft, From Measured Field Change, Current, and Channel Geometry

Direct current measurements are available near the attachment point from both natural cloud-to-ground lightning and rocket-triggered lightning, but little is known about the rise time and peak amplitude of return-stroke currents aloft. We present, as functions of height, current amplitudes, rise times, and effective propagation velocities that have been estimated with a novel remote-sensing technique from data on 24 subsequent return strokes in six different lightning flashes that were triggering at the NASA Kennedy Space Center, FL, during 1987. The unique feature of this data set is the stereo pairs of still photographs, from which three-dimensional channel geometries were determined previously. This has permitted us to calculate the fine structure of the electric-field-change (E) waveforms produced by these strokes, using the current waveforms measured at the channel base together with physically reasonable assumptions about the current distributions aloft. The computed waveforms have been compared with observed E waveforms from the same strokes, and our assumptions have been adjusted to maximize agreement. In spite of the non-uniqueness of solutions derived by this technique, several conclusions seem inescapable: 1) The effective propagation speed of the current up the channel is usually significantly (but not unreasonably) faster than the two-dimensional velocity measured by a streak camera for 14 of these strokes. 2) Given the deduced propagation speed, the peak amplitude of the current waveform often must decrease dramatically with height to prevent the electric field from being over-predicted. 3) The rise time of the current wave front must always increase rapidly with height in order to keep the fine structure of the calculated field consistent with the observations.

Willett, J. C.↗
NASA NTRS2003

Standards Advisor-Advanced Information Technology for Advanced Information Delivery

Developers of space systems must deal with an increasing amount of information in responding to extensive requirements and standards from numerous sources. Accessing these requirements and standards, understanding them, comparing them, negotiating them and responding to them is often an overwhelming task. There are resources to aid the space systems developer, such as lessons learned and best practices. Again, though, accessing, understanding, and using this information is often more difficult than helpful. This results in space systems that: 1. Do not meet all their requirements. 2. Do not incorporate prior engineering experience. 3. Cost more to develop. 4. Take longer to develop. The NASA Technical Standards Program (NTSP) web site at http://standards.nasa.gov has made significant improvements in making standards, lessons learned, and related material available to space systems developers agency-wide. The Standards Advisor was conceived to take the next steps beyond the current product, continuing to apply evolving information technology that continues to improve information delivery to space systems developers. This report describes the features of the Standards Advisor and suggests a technical approach to its development.

Hawker, J. Scott↗
NASA NTRS2004

Space Weathering of Apollo 16 Sample 62255: Lunar Rocks as Witness Plates for Deciphering Regolith Formation Processes

Space weathering, or alteration that occurs at the surfaces of materials exposed directly to space, has been one of the primary areas of focus of lunar studies for the past several years. It is caused by processes such as micrometeorite impacts and solar wind bombardment, and effects can include microcraters, spall zones, and vapor deposits. Much of the recent work on space weathering has been concentrated on nanoscale features, especially the amorphous rims commonly found on individual lunar soil grains. The rims typically contain nanophase Fe metal globules, which, along with Fe metal globules in agglutinates, have a profound effect on optical properties of lunar soils. The nanophase metallic iron globules cause the characteristic optical changes (reddening and darkening) found in mature lunar soils.

Wentworth, S. J.↗
NASA NTRS2006

Real Time On-line Space Research Laboratory Environment Monitoring with Off-line Trend and Prediction Analysis

One of the responsibilities of the NASA Glenn Principal Investigator Microgravity Services is to support NASA sponsored investigators in the area of reduced-gravity acceleration data analysis, interpretation and the monitoring of the reduced-gravity environment on-board various carriers. With the International Space Station currently operational, a significant amount of acceleration data is being down-linked and processed on ground for both the space station onboard environment characterization (and verification) and scientific experiments. Therefore, to help principal investigator teams monitor the acceleration level on-board the International Space Station to avoid undesirable impact on their experiment, when possible, the NASA Glenn Principal Investigator Microgravity Services developed an artificial intelligence monitoring system, which detects in near real time any change in the environment susceptible to affect onboard experiments. The main objective of the monitoring system is to help research teams identify the vibratory disturbances that are active at any instant of time onboard the International Space Station that might impact the environment in which their experiment is being conducted. The monitoring system allows any space research scientist, at any location and at any time, to see the current acceleration level on-board the Space Station via the World Wide Web. From the NASA Glenn s Exploration Systems Division web site, research scientists can see in near real time the active disturbances, such as pumps, fans, compressor, crew exercise, re-boost, extra-vehicular activity, etc., and decide whether or not to continue operating or stopping (or making note of such activity for later correlation with science results) their experiments based on the g-level associated with that specific event. A dynamic graphical display accessible via the World Wide Web shows the status of all the vibratory disturbance activities with their degree of confidence as well as their g-level contribution to the environment. The system can detect both known and unknown vibratory disturbance activities. It can also perform trend analysis and prediction by analyzing past data over many Increments of the space station for selected disturbance activities. This feature can be used to monitor the health of onboard mechanical systems to detect and prevent potential system failure as well as for use by research scientists during their science results analysis. Examples of both real time on-line vibratory disturbance detection and off-line trend analysis are presented in this paper. Several soft computing techniques such as Kohonen s Self-Organizing Feature Map, Learning Vector Quantization, Back-Propagation Neural Networks, and Fuzzy Logic were used to design the system.

Jules, Kenol↗
NASA NTRS2003

Project Status Update and SIM Science Breadth Discussion for the Origins Subcommittee (OS)

This viewgraph presentation is composed of two sections The first reviews the features and the science goals of the Space Interferometry Mission (SIM). The goals are: (1) Perform a search for other planetary systems by surveying 2000 nearby stars for astrometric signatures of planetary companion, (2) Survey a sample of 200 nearby stars for orbiting planets down to terrestrial-type masses (3) Improve best current catalog of star positions by >lOOx and extend to fainter stars to allow extension of stellar knowledge to include our entire galaxy (4) Study dynamics and evolution of stars and star clusters in our galaxy to understand how our galaxy was formed and how it will evolve. (5) Calibrate luminosities of important stars and cosmological distance indicators to improve our understanding of stellar processes and to measure precise distance in the distant universe. The presentation also reviews the accomplishments since 2002, the plans for the subsequent 6 months. The second entitled "The Breadth of SIM Science," reviews SIM science goals in a larger context. SIM will serve to complement and pave the way for the Terrestrial Planet Finder (TPF). SIM observations of the motions of stars will tell us about the distribution of all gravitating mass (light plus dark matter) in the Galaxy. SIM observations of the motions of dwarf galaxies around our own will determine the mass distribution (light plus dark matter in the Halo. SIM will greatly extend these observations to test the theories of accretion disks around super massive black holes. SIM has advantages for studying AGN and other very compact objects.

Michelson stellar interferometers↗