Prospects for destructive self-induced interactions in a vortex pair
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Rossow, Vernon J.↗
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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.↗
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.↗
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↗
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.↗
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↗
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↗
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↗
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.↗
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.↗
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.↗
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.↗
On the design of man-machine systems - Principles, practices and prospects
A large proportion of the problems associated with complex systems have been attributed, at least in part, to the human operators, maintenance personnel, or managers who work within these systems. It appears, therefore, that improving man-machine system design may contribute to decreasing substantially the frequency of problems in complex systems. In this paper, alternative views of how the design of man-machine systems might be improved are described and contrasted. A two-part approach for achieving the desired improvements is proposed.
Rouse, William B.↗
Europa - The prospects for an ocean
Tidal dissipation in the satellites of a giant planet may provide sufficient heating to maintain a liquid water ocean below a thin ice layer. In the solar system, Europa, one of the Galilean satellites of Jupiter, may have such an ocean. Both theoretical calculations and certain observations support its existence, although proof is lacking. The putative ocean would probably have temperatures, pressures, and chemistry conducive to biologic activity. However, the environment would be severely energy limited. Possible energy sources include transient transmission of sunlight through fractures in the ice and hydrothermal activity on the ocean floor. While temporary conditions could exist that are within the range of adaptation of certain terrestrial organisms, origin of life under such conditions seems unlikely. In other solar systems, however, larger satellites with more significant heat flow could provide environments that are stable over an order of aeons and in which life could perhaps evolve.
Reynolds, R. T.↗
The technology issues and the prospects for the use of lithium batteries in space
Lithium Primary and Secondary Cells are being considered for applications in space to enhance energy storage capability. In this paper the authors describe the past, present and future application and program objectives as well as the technology issues that must be addressed.
Halpert, Gerald↗
Solar spectroscopy in the far-ultraviolet-X-ray wavelength regions - Status and prospects
Progress made by space experimentation in obtaining solar spectra satisfactory for extensive applications of plasma diagnostic techniques is reviewed. Particular attention is given to solar spectroscopy in the FUV-X-ray wavelength regions in the 1.7-2000 A range. The quality of the available spectra obtained in each region is evaluated, concentrating on spectral resolution, wavelength coverage and accuracy, and line intensity and line-profile information.
Feldman, U.↗
Prospects for coherent lidar systems and technology development
A coherent lidar is a powerful technique for remote measurements of velocity fields, and at middle infrared wavelengths it also has advantages compared with direct-detection lidar in extended range measurement of atmospheric species. These qualities are obtained at the cost of additional complexity and more stringent requirements on the coherence properties of the lasers which are used. An attempt is made to summarize the technological requirements of certain coherent lidar applications and discuss relevant technology development, emphasizing the CO2 and solid-state laser components.
Menzies, Robert T.↗
The prospects for detecting spectral shifts due to satellite sensor aging
Along with responsivity changes due to sensor aging, there may be concurrent spectral changes. A field-measurement approach for detecting postlaunch spectral changes is described. For illustration, one hypothetical model of change (spectral band shift) is explored through simulation for five satellite sensors. Two different types of natural terrain - vegetation and bare soil - are used as test targets.
Suits, G.↗