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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Genesis stories for the millisecond pulsar

Theoretical models proposed to explain the origin of the millisecond pulsar (MP) PSR 1937+214 are reviewed, examining their ability to explain its low surface dipole magnetic field (B), its low birth temperature (less than 10 to the 8th K), the absence of a companion or remnant, and its low velocity perpendicular to the Galactic plane. The models discussed are a single isolated explosion forming a rapidly spinning neutron star, spin-up of a dead pulsar by accretion from a companion, collapse of an accreting spinning white dwarf, and fusion of a tight binary composed of two old neutron stars. Although all of the models have difficulties in explaining one or more of the MP characteristics, the second model is found to be most probable in the light of present knowledge. The lack of a companion is explained by its tidal disruption after it had fed the accreting pre-pulsar for 1 Gyr or more and its mass had decreased to about 0.01 solar mass. Neutron stars accreting in this way have been observed in Galactic-bulge X-ray sources.

Ruderman, M. A.↗
NASA NTRS1985

Valles Marineris Basin Beds: a Complex Story

High resolution stereoimages of the central Valles Marineris enabled detailed geologic mapping on Ophir and Candor Chasmata. Abundant light colored deposits, both layered and massive, fill the chasmata in this region. Units within these deposits were identified by their erosional characteristics and superposition and cross cutting relations. The Valles Marineris beds reflect a history of repeated faulting, volcanic eruptions, and deposition and erosion, resulting in stratigraphic sequences with several unconformities. Because of the preponderance of apparent volcanic deposits inside the troughs, the chasmata may not be simple grabens, but rather giant volcano tectonic depressions. Major events in chasmata development are examined.

Lucchitta, B. K.↗
NASA NTRS1985

Study of hadron bundles observed in Chacaltaya two-story emulsion chamber

The existence of hadron-rich families associated with few gamma-ray emission named Centauro and Mini-Centauro phemonena was reported. It was investigated whether these are produced by the special type of interaction different from the ordinary pion multiple production or not. The experimental results are compared with simulation calculation based on ordinary multiple pion production model. Both hadron multiplicity distribution, obtained from the present observation and the simulation calculation, show almost the same distribution which means that hadron bundles of such smaller multiplicities are considered to originate from successive interactions of surviving nucleon with the nature of multiple production during passage through the atmosphere.

Aoki, H.↗
NASA NTRS1987

Reaching for the stars: The story of astronaut training and the lunar landing

The training for the Mercury, Gemini, and Apollo programs is described. The form and function of training and the historical background which shaped the nature of that training are reviewed. For the three programs, the astronaut selection, the meeting of training requirements, and program management are addressed.

Goldstein, Stanley H.↗
NASA NTRS1988

Stellar wind variations in HD 45166: The continuing story

High resolution SWP IUE spectra of HD 45166 (qWR+B8V) obtained over a 36 hr continuous run, together with earlier observations, reveal 2 distinct modes of UV variability in this object. Gross, epoch-linked changes are seen in the strengths of the qWR emission lines, accompanied by large changes in its highly ionized photospheric absorption spectrum. Rapid (hours) variability in strong, multiple, high velocity, wind discrete absorption components (DAC), in the CIV lambda 1550 resonance lines, which superpose to give the appearance of a broad P Cygni absorption profile at many epochs is also observed. These multiple DAC's (often at least 3 are seen) propagate in velocity, from 0.6 to 1.0 v inf, on a timescale of 1 day, implying an acceleration of 180 cm/s comparable to that seen in O-type stars.

Willis, Allan J.↗
NASA NTRS1989

Neptune's story

It is conjectured that Triton was captured from a heliocentric orbit as the result of a collision with what was then one of Neptune's regular satellites. The immediate post-capture orbit was highly eccentric. Dissipation due to tides raised by Neptune in Triton caused Triton's orbit to evolve to its present state in less than one billion years. For much of this time Triton was almost entirely molten. While its orbit was evolving, Triton cannibalized most of the regular satellites of Neptune and also perturbed Nereid, thus accounting for that satellite's highly eccentric and inclined orbit. The only regular satellites of Neptune that survived were those that formed well within 5 Neptune radii, and they move on inclined orbits as the result of chaotic perturbations forced by Triton.

Goldreich, P.↗
NASA NTRS1992

A recent Cleanroom success story: The Redwing project

Redwing is the largest completed Cleanroom software engineering project in IBM, both in terms of lines of code and project staffing. The product provides a decision-support facility that utilizes artificial intelligence (AI) technology for predicting and preventing complex operating problems in an MVS environment. The project used the Cleanroom process for development and realized a defect rate of 2.6 errors/KLOC, measured from first execution. This represents the total amount of errors that were found in testing and installation at three field test sites. Development productivity was 486 LOC/PM, which included all development labor expended in design specification through completion of incremental testing. In short, the Redwing team produced a complex systems software product with an extraordinarily low error rate, while maintaining high productivity. All of this was accomplished by a project team using Cleanroom for the first time. An 'introductory implementation' of Cleanroom was defined and used on Redwing. This paper describes the quality and productivity results, the Redwing project, and how Cleanroom was implemented.

Hausler, Philip A.↗
NASA NTRS1993

Angrite LEW87051: Are the olivines pheno's or xeno's? A continuing story

The achondrite LEW87051 is a porphyritic basalt consisting of large subhedral to euhedral zoned olivines in a finer-grained groundmass. The texture of this groundmass looks remarkably like a quenched melt. However, although the rock is clearly igneous, its exact origins and history are under dispute. From petrographic observations, Prinz felt that the large olivines were xenocrysts and that the zoning reflected interaction with an unrelated, CAI-enriched melt. McKay et al. was able to model the olivines as phenocrysts, whose zoning was the result of a parent melt that changed in composition as material crystallized, e.g., fractional crystallization in a closed system, and calculated a parent melt composition. Jurewicz and McKay compared the calculated parent melt composition with actual partial melts from CV and CM chondrites. They showed that the calculated melt was substantially different from equilibrium melts of these chondrites; however, the LEW87051 groundmass composition was similar to some of the low temperature partial melts, although slightly enriched in AN (or depleted in OL) components. This study presents the results of an independent petrologic look at other olivines in LEW87051 and the preliminary results of a quantitative model for the major zoning in these olivines as diffusive-exchange with an olivine-saturated, low temperature angritic melt.

Jurewicz, A. J. G.↗
NASA NTRS1994

The in-flight calibration of the Hubble Space Telescope fine guidance sensors, 2 (a success story)

The Hubble Space Telescope's fine guidance sensors (FGS's) are unique in the performance levels being attempted; spacecraft control and astrometric research with accuracies better than 3 milli-arcseconds (mas) are the ultimate goals. This paper presents a review of the in-flight calibration of the sensors, describing both the algorithms used and the results achieved to date. The work was done primarily in support of engineering operations related to spacecraft pointing and control and secondarily in support of the astrometric science calibration effort led by the Space Telescope Astrometry Team. Calibration items of principal interest are distortion, sensor magnification, and relative alignment. An initial in-flight calibration of the FGS's was performed in December 1990; this calibration has been used operationally over the past few years. Followup work demonstrated that significant, unexpected temporal variations in the calibration parameters are occurring; provided good characterization of the variation; and set the stage for a distortion calibration designed to achieve the full design accuracy for one of the FGS's. This full distortion calibration, using data acquired in January 1993, resulted in a solution having single-axis residuals with a standard deviation of 2.5 mas. Scale and alignment calibration results for all of the FGS's have been achieved commensurate with the best ground-based astrometric catalogs (root-mean-square error approximately 25 mas). A calibration monitoring program has been established to allow regular updates of the calibration parameters as needed.

Welter, Gary L.↗
NASA NTRS1989

The Story of PI

The early history and the uses of the mathematical notation - pi - are presented through both film footage and computer animation in this 'Project Mathematics' series video. Pi comes from the first letter in the Greek word for perimeter. Archimedes, and early Greek mathematician, formulated the equations for the computation of a circle's area using pi and was the first person to seriously approximate pi numerically, although only to a few decimal places. By 1985, pi had been approximated to over one billion decimal places and was found to have no repeating pattern. One use of pi is the application of its approximation calculation as an analytical tool for determining the accuracy of supercomputers and software designs.

Apostol, Tom M.↗
NASA NTRS1996

Lewis Research Center: Commercialization Success Stories

The NASA Lewis Research Center, located in Cleveland, Ohio, has a portfolio of research and technology capabilities and facilities that afford opportunities for productive partnerships with industry in a broad range of industry sectors. In response to the President's agenda in the area of technology for economic growth (Clinton/Gore 1993), the National Performance Review (1993), NASA's Agenda for Change (1994), and the needs of its customers, NASA Lewis Research Center has sought and achieved significant successes in technology transfer and commercialization. This paper discusses a sampling of Lewis Research Center's successes in this area, and lessons learned that Lewis Research Center is applying in pursuit of continuous improvement and excellence in technology transfer and commercialization.

Heyward, Ann O.↗
NASA NTRS1997

The In-Orbit Performance of Batteries on the Skynet 4 Spacecraft Fleet: A NIckel-Cadmium Success Story

The SKYNET 4 constellation consists of three spacecraft which were launched between December 1988 and August 1990. The spacecraft are three-axis stabilized geostationary earth-orbiting military communications satellites with a design life of seven years on station. With the mission objective achieved all the batteries continue to give excellent performance. This paper presents a review of the history of the six batteries from cell procurement to the end of their design life and beyond. Differences in operational strategies are discussed and the lifetime trends in performance are analyzed. The combination of procurement acceptance criteria and the on-station battery management strategy utilized are presented as the prime factors in achieving completely successful battery performance throughout the mission.

Johnson, P. J.↗
NASA NTRS2000

Marshall Convergent Coating Development Team: An Aerospace Success Story

The external thermal insulation systems for the Space Shuttle solid rocket boosters and the Air Force Titan IV payload fairings were in jeopardy due to EPA regulatory problems, endangering the flight status of both vehicles. The Marshall Convergent Coating (MCC-1) Development Team was formed in February 1994 to develop and implement an EPA-compliant external thermal insulation system for both systems. MCC-1 made use of a process known as Convergent Spray Technology (CST), a solventless, sprayable process that eliminated the environmentally hazardous chemicals involved with the old methods. Implemented in record time, the new insulation was so successful that it was selected for two additional flight vehicles, Boeing's Sea Launch and Delta TV. The activity also led to commercial spin-off pilot projects. The team continues today to share data between the various production sites, resolve production issues, expand the material's use, and consider potential improvements for the future.

Lester, Carl N.↗
NASA NTRS2000

Fault Tree in the Trenches, A Success Story

Getting caught up in the explanation of Fault Tree Analysis (FTA) minutiae is easy. In fact, most FTA literature tends to address FTA concepts and methodology. Yet there seems to be few articles addressing actual design changes resulting from the successful application of fault tree analysis. This paper demonstrates how fault tree analysis was used to identify and solve a potentially catastrophic mechanical problem at a rocket motor manufacturer. While developing the fault tree given in this example, the analyst was told by several organizations that the piece of equipment in question had been evaluated by several committees and organizations, and that the analyst was wasting his time. The fault tree/cutset analysis resulted in a joint-redesign of the control system by the tool engineering group and the fault tree analyst, as well as bragging rights for the analyst. (That the fault tree found problems where other engineering reviews had failed was not lost on the other engineering groups.) Even more interesting was that this was the analyst's first fault tree which further demonstrates how effective fault tree analysis can be in guiding (i.e., forcing) the analyst to take a methodical approach in evaluating complex systems.

Long, R. Allen↗