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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Antimatter propulsion, status and prospects

The use of advanced propulsion techniques must be considered if the currently envisioned launch date of the manned Mars mission were delayed until 2020 or later. Within the next thirty years, technological advances may allow such methods as beaming power to the ship, inertial-confinement fusion, or mass-conversion of antiprotons to become feasible. A propulsion system with an ISP of around 5000 s would allow the currently envisioned mission module to fly to Mars in 3 months and would require about one million pounds to be assembled in Earth orbit. Of the possible methods to achieve this, the antiproton mass-conversion reaction offers the highest potential, the greatest problems, and the most fascination. Increasing the production rates of antiprotons is a high priority task at facilities around the world. The application of antiprotons to propulsion requires the coupling of the energy released in the mass-conversion reaction to thrust-producing mechanisms. Recent proposals entail using the antiprotons to produce inertial confinement fusion or to produce negative muons which can catalyze fusion. By increasing the energy released per antiproton, the effective cost, (dollars/joule) can be reduced. These proposals and other areas of research can be investigated now. These short term results will be important in assessing the long range feasibility of an antiproton powered engine.

Howe, Steven D.↗
NASA NTRS1986

Prospecting for planets in circumstellar dust - Sifting the evidence from Beta Pictoris

IRAS and near-IR coronographic data for the A5V star Beta Pic are analyzed for evidence of planetary formation. The light scattered from the central star in the system is integrated along the distance to the star to determine the disk magnitude at various distances from the star. A modified gamma distribution is applied to evaluate the scattering coefficient to test a hypothesis that the inner 30 AU of the disk has been swept out by planets. The scattering from the region around Beta Pic is compared with scattering around other A5V stars. Finally, the IR data at 0.89 micron is compared with scattering at the coronograph wavelengths. No evidence is found to support the hypothesis of clearing in the inner disk, although large particle densities can be found very close to Beta Pic. The study illustrates the effectiveness of using scattered light and IR data to discover and characterize matter distributions circumstellar disks.

Diner, D. J.↗
NASA NTRS1986

Prospects for advanced rocket-powered launch vehicles

The potential for advanced rocket-powered launch vehicles to meet the challenging cost, operational, and performance demands of space transportation in the early 21st century is examined. Space transportation requirements from recent studies underscoring the need for growth in capacity in support of an increasing diversity of space activities and the need for significant reductions in operational and life-cycle costs are reviewed. Fully reusable rocket powered concepts based on moderate levels of evolutionary advanced technology are described. These vehicles provide a broad range of attractive concept alternatives with the potential to meet demanding operational and cost goals and the flexibility to satisfy a variety of vehicle architecture, mission, vehicle concept, and technology options.

Eldred, C. H.↗
NASA NTRS1986

Prospects for observations of relativistic effects in the solar system

In this paper the authors concentrate on an experiment that promises a dramatic improvement in a classical test of general relativity - the deflection of light by solar gravity. The goal is to measure the post-post-Newtonian contribution of nearly 11 microarcseconds to this deflection. The proposed technique is based on use of an astrometric optical interferometer, POINTS, which could be operated from the bay of the Space Shuttle, mounted on the proposed Space Station, or supported by an independent spacecraft. POINTS should be able to measure the separation of stars about 90 deg apart with an uncertainty of only a few microarcseconds.

Reasenberg, R. D.↗
NASA NTRS1986

Thin-film temperature sensors for gas turbine engines Problems and prospects

The erosion and corrosion of thermocouples used to measure the temperature in turbine engines are studied. Structural and metallurgical interactions and instabilities at thermocouple interfaces are analyzed. Consideration is given to the adhesion, dielectric quality, surface topography, and hardness of the thermal oxides; it is observed that the structural and thermoelectric stability of thin-film thermocouple elements depends on adhesion, surface topography, and dielectric strength. The electrical conductivity and impurity content of the oxide scale are evaluated. Methods for improving the adhesion of thermocouples on the alumina surfaces are described. Compositional inhomogeneities in the sensors and contamination of the thermocouple elements are examined. The fabrication of the thermocouples is discussed. It is noted that Al2O3 and Si3N4 are useful for developing stable thermocouple elements on the surface of the blades and vanes.

Budhani, R. C.↗
NASA NTRS1986

Astrophysical data on 5 eV to 1 keV radiation from the radiative decay of fundamental particles - Current limits and prospects for improvement

Line emission from the decay of fundamental particles, integrated over cosmological distances, can give rise to detectable spectral features in the diffuse astronomical background between 5 eV and 1 keV. Spectroscopic observations may allow these features to be separated from line emission from the numerous local sources of radiation. The current observational status and existing evidence for such features are reviewed. No definitive detections of nongalactic line features have been made. Several local sources of background mask the features at many wavelengths and confuse the interpretation of the data. No systematic spectral observations have been carried out to date. Upcoming experiments which can be expected to provide significantly better constraints on the presence of spectral features in the diffuse background from 5 eV to 1 keV are reviewed.

Bowyer, Stuart↗
NASA NTRS1985

NASA's new technology reporting system: A review and future prospects

A systematic effort is made to describe how NASA's new technology reporting system operates today, and how that system might be enhanced. The system is documented in terms of organization, operational practices, and other program benefits. Identified and assessed are incentives or disincentives to reporting, program management, program follow through, and the feasibility of various means for improving the general process. NASA has the only system in the Federal Government for capturing and disseminating new technology developed under its sponsorship of research and development. This system can be improved in many ways, some of which require additional resources and/or more senior management attention, but many of which can be instituted within the authority of the leadership of the Technology Utilization program. The suggested options and actions presented are mutually compatible. Any single action will contribute to improving the process. However, the first and most important step is undoubtedly to gain senior management's attention to the central role played by a vigorous new technology reporting system in the success and value of NASA's broader technology utilization and technology transfer activities.

Chapman, Richard L.↗
NASA NTRS1987

Plant cell technologies in space: Background, strategies and prospects

An attempt is made to summarize work in plant cell technologies in space. The evolution of concepts and the general principles of plant tissue culture are discussed. The potential for production of high value secondary products by plant cells and differentiated tissue in automated, precisely controlled bioreactors is discussed. The general course of the development of the literature on plant tissue culture is highlighted.

Kirkorian, A. D.↗
NASA NTRS1987

The imaging of extra-galactic low-energy gamma-ray sources prospects, techniques, and instrumentation

Improved understanding of the nature of active galaxies will require detailed observations of 10 to 20 sources, while understanding of their gamma ray luminosity function and its evolution will require the detection of approximately 100 sources. Instruments capable of detecting 100 active galaxies at low-energy, gamma ray energies are achievable. The angular resolution of an instrument, as well as its sensitivity, can limit the number of sources it can observe. An investigation of the angular resolution requirements for future low-energy gamma ray instruments is presented. It was found that the strictest requirements arise not from the need to resolve detectable sources, but from the need to control the level of direction-to-direction fluctuations in the diffuse background level. It was concluded that gamma-ray instruments capable of detecting 100 active galaxies must have sub-degree angular resolution. The use of the coded aperture imaging technique is proposed as a method of achieving accurate control of systematic errors and fine angular resolution without unduly increasing the time needed to conduct full sky surveys. An analysis of coded aperture imaging is presented for instruments that employ masks based on hexagonal uniformly redundant arrays. An instrument, the gamma-ray imaging payload, was built that employs these imaging techniques. The design and testing of the instrument is described in detail. Preliminary results from a balloon flight of the instruments are shown, demonstrating its imaging performance.

Finger, Mark Harold↗
NASA NTRS1987

Water facilities in retrospect and prospect: An illuminating tool for vehicle design

Water facilities play a fundamental role in the design of air, ground, and marine vehicles by providing a qualitative, and sometimes quantitative, description of complex flow phenomena. Water tunnels, channels, and tow tanks used as flow-diagnostic tools have experienced a renaissance in recent years in response to the increased complexity of designs suitable for advanced technology vehicles. These vehicles are frequently characterized by large regions of steady and unsteady 3-D flow separation and ensuing vortical flows. The visualization and interpretation of the complicated fluid motions about isolated vehicle components and complete configurations in a time and cost effective manner in hydrodynamic test facilities is a key element in the development of flow control concepts, and, hence, improved vehicle designs. A historical perspective of the role of water facilities in the vehicle design process is presented. The application of water facilities to specific aerodynamic and hydrodynamic flow problems is discussed, and the strengths and limitations of these important experimental tools are emphasized.

Erickson, Gary E.↗
NASA NTRS1987

Prospects for observations of nucleosynthetic gamma-ray lines and continuum from SN 1987A

Expected flux levels for nucleosynthetic gamma-ray line and continuum emissions from SN 1987A are calculated for several models. The dominant line emission is from freshly synthesized Ni-56 and its decay daughters, and the continuum is from Compton scattering of line photons. For a 15 solar mass Type II model, the light curve for the 0.847 MeV gamma-ray line peaks in September 1988 at 3 x 10 to the -4th photons/sq cm/s. This is detectable only by new, ultrasensitive balloon-borne spectrometers. For models with substantial mass loss from their envelopes, the peak is in early 1988 at about 0.01 photons/sq cm/s, which is detectable at high significance levels by all current instruments. The continuum emission in the 0.05-0.5 MeV band peaks about 100 days before the 0.847 MeV line peak. This Compton precursor is observable at about the same significance level as the lines.

Gehrels, Neil↗
NASA NTRS1987

Prospects for Eulerian CFD analysis of helicopter vortex flows

The applicability of current finite-volume CFD algorithms based on the Euler equations to the vortex flow over a helicopter in forward flight is investigated analytically. The general characteristics of the flow are reviewed; existing Euler, Navier-Stokes, perturbation, high-order, and adaptive methods are briefly characterized; and a novel Eulerian/Lagrangian approach with entropy and vorticity corrections is presented in detail. Numerical results for simple convection of a finite-core Lamb vortex moving downstream with its axis perpendicular to the flow are presented in graphs, and the possibility of extending the method to three-dimensional, viscous, and shock flows is discussed.

Drela, Mark↗
NASA NTRS1987

Prospects for gamma-ray line observations of individual supernovae

The gamma-ray line emission from individual type I and type II supernovae are studied using numerical simulations and photon propagation codes to predict the flux levels and line shapes. For both types, the gamma ray lines with the highest flux from an individual event are the 0.847 and 1.238 MeV lines from the Ni-56 to Co-56 to Fe-56 decay chain. For type I supernovae, the 0.847 MeV line peaks at about 70 days after event onset. The historical record indicates an approximate discovery rate of once in 10 years for balloon-borne instruments, once in two to three years for the Gamma-Ray Observatory, and once in one to two years for a proposed space mission. The 0.847 MeV line flux from type II supernovae peaks at about 600 days after event onset at a low level which restricts observations to the events in the Galaxy and its nearest neighbors. The expected line shape is narrower than for type I supernovae.

Gehrels, Neil↗
NASA NTRS1987

On the prospect of using butterfly diagrams to predict cycle minimum

Features enabling the prediction of the beginning and the length of a solar cycle, in addition to the turning points in the period-growth dichotomy, have been identified based on butterfly diagrams for the period from 1874 to the present. The present results indicate that cycle 21 will be a long-period cycle ending after July 1987. On the assumption that April 1985 was the first occurrence of high latitude new cycle (cycle 22) spots during the decline of cycle 21 (the old cycle), it is suggested that the last occurrence of high latitude old cycle spots was September 1983 and that the minimum for cycle 22 will be about 1986.7 + or - 1.1 yr.

Wilson, Robert M.↗
NASA NTRS1988

Astrophysical implications and observational prospects of X-ray polarimetry

X-ray polarimetry is a prime tool for investigating the physics of compact objects, which has not been adequately exploited thus far. However, current low-cost technology and modest launch requirements could provide a large number of positive observations with a sensitivity factor at least 100 greater than 10 years ago.The amount of astrophysical information potentially to be gained from this is enormous. The introduction of polarimetric information (direction and degree) would bring a quantum jump in the parameter space used to investigate compact objects, from the current two (spectra and time variability) to four independent parameters that models need to satisfy. This should greatly improve our ability to discriminate between various possible models. Such observations could lead to an elucidation of the rotation-powered and accretion-powered pulsar radiation mechanisms, could help clinch the identification of black hole canditates, and could decide between thermal and nonthermal AGN radiation models, as well as pin down the geometry of the accretion flows in both galactic and extragalactic sources.

Meszaros, P.↗
NASA NTRS1988

Space science at NASA - Retrospect and prospect

Following a brief overview of past accomplishments in space science, a status report is given concerning progress toward recovering from the Challenger accident and a number of trends are described which are likely to have a major influence on the future of the NASA Space Science program. Key changes in process include a trend toward a program centered on the use of large, long-lived facilities, the emergence of strong space capabilities outside the U.S., and steps being taken toward the diversification of NASA's launch capability. A number of recent planning activities are also discussed. Major considerations which will specifically need to be taken into account in NASA's prgram planning include the need for provision of a spectrum of flight activities and the need to recognize likely resource limitations and to do more realistic program planning.

Rosendhal, Jeffrey D.↗
NASA NTRS1987

Prospective lunar, planetary and deep space applications of tethers

Projected flights of an internationally managed Tethered Satellite System from the Space Shuttle in the early 1990s will investigate the behavior, first, of an insulated conducting wire 20 km long as it travels at orbital speeds through the ionosphere and earth magnetic field; subsequently, a nonconducting tether will be used to lower an instrumented 'subsatellite' 100 km downward to investigate upper-atmosphere conditions. Further consideration is presently given to other scientific, electrodynamic, transportational, and artificial gravity-generating applications of the tether concept.

Penzo, Paul A.↗