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All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Telescience at the University of California, Berkeley

The University of California at Berkeley (UCB) is a member of a university consortium involved in telescience testbed activities under the sponsorship of NASA. The Telescience Testbed Project consists of three experiments using flight hardware being developed for the Extreme Ultraviolet Explorer project at UCB's Space Sciences Laboratory. The first one is a teleoperation experiment investigating remote instrument control using a computer network such as the Internet. The second experiment is an effort to develop a system for operation of a network of remote workstations allowing coordinated software development, evaluation, and use by widely dispersed groups. The final experiment concerns simulation as a method to facilitate the concurrent development of instrument hardware and support software. Progress in these areas is described.

Chakrabarti, S.↗
NASA NTRS1988

The Propagation Information Center at the University of Colorado

A Propagation Information Center is in the process of being established at the University of Colorado with connections to NAPEX and to the NASA program at Colodado University (CU) for Interdisciplinary Research in Telecommunications Policy and Technology Issues. The Propagation Information Center was conceived as a response to several items in the Science Review of the NASA Propagation Program carried out in September of 1986 by a distinguished panel of experts. The program for the Center is conceived as including archival aspects: a memory of past work by NAPEX members; accounts of relevant research activities around the world; papers published in pertinent areas of propagation; and pertinent propagation data files. Duties of the Center should include: exchanging information on future plans with research organizations around the world; scanning the literature for possible contributions; carrying out quick response studies requested by program management; conducting customer surveys of users; preparing a quarterly newsletter to help maintain communication amongst program participants; and assisting students and faculty who are working on policy issues for NASA in the propagation field.

Smith, Ernest K.↗
NASA NTRS1988

Phase transitions as the origin of large scale structure in the universe

A review of the formation of large scale structure through gravitational growth of primordial perturbations is given. This is followed by a discussion of how symmetry breaking phase transitions in the early universe might have produced the required perturbations, in particular through the formation and evolution of a network of cosmic strings. Finally, the statistical mechanics of string networks, for both cosmic and fundamental strings is discussed, leading to some more speculative ideas on the possible role of fundamental strings (superstrings or heterotic strings) in the very early universe.

Turok, Neil↗
NASA NTRS1984

Transportable, university-level educational programs in interactive information storage and retrieval systems

Pursuant to the specifications of a research contract entered into in December, 1983 with NASA, the Computer Science Departments of the University of Southwestern Louisiana and Southern University will be working jointly to address a variety of research and educational issues relating to the use, by non-computer professionals, of some of the largest and most sophiticated interactive information storage and retrieval systems available. Over the projected 6 to 8 year life of the project, in addition to NASA/RECON, the following systems will be examined: Lockheed DIALOG, DOE/RECON, DOD/DTIC, EPA/CSIN, and LLNL/TIS.

Dominick, Wayne D.↗
NASA NTRS1984

A report on the USL NASA/RECON project. Part 1: The development of a transportable, university level, IS and R educational program

A project is described which has as its goal the production of a set of system-independent, discipline-independent, transportable college level courses to educate science and engineering students in the use of large-scale information storage and retrieval systems. This project is being conducted with the cooperation and sponsorship of NASA by R and D teams at the University of Southwest Louisiana and Southern University. Chapter 1 is an introduction, providing an overview and a listing of the management phases. Chapter 2 furnishes general information regarding accomplishments in areas under development. Chapter 3 deals with the development of the course materials by presenting a series of diagrams and keys to depict the progress and interrelationships of various tasks and sub-tasks. Chapter 4 presents plans for activities to be conducted to complete and deliver course materials. The final chapter is a summary of project objectives, methods, plans, and accomplishments.

Dominick, Wayne D.↗
NASA NTRS1988

The distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter dominated universe

The evolution and distribution of galaxies and the intergalactic medium (IGM) have been studied, along with collisionless dark matter in a Universe dominated by cold dark matter. The Einstein-deSitter universe with omega sub 0 = 1 and h = 0.5 was considered (here h = H sub 0 bar 100/kms/Mpc and H sub 0 is the present value of the Hubble constant). It is assumed that initially dark matter composes 90 pct and baryonic matter composes 10 pct of total mass, and that the primordial baryonic matter is comprised of H and He, with the abundance of He equal to 10 pct of H by number. Galaxies are allowed to form out of the IGM, if the total density and baryonic density satisfy an overdensity criterion. Subsequently, the newly formed galaxies release 10 to the 60th ergs of energy into the IGM over a period of 10 to the 8th years. Calculations have been performed with 32 to the 3rd dark matter particles and 32 to the 3rd cells in a cube with comoving side length L = 9.6/h Mpc. Dark matter particles and galaxies have been followed with an N-body code, while the IGM has been followed with a fluid code.

Ryu, Dongsu↗
NASA NTRS1989

On the generation of a bubbly universe - A quantitative assessment of the CfA slice

A first attempt is made to calculate the properties of the matter distribution in a universe filled with overlapping bubbles produced by multiple explosions. Each spherical shell follows the cosmological Sedov-Taylor solution until it encounters another shell. Thereafter, mergers are allowed to occur in pairs on the basis of N-body results. At the final epoch, the matrix of overlapping shells is populated with 'galaxies' and the properties of slices through the numerically constructed cube compare well with CfA survey results for specified initial conditions. A statistic is found which measures the distance distribution from uniformly distributed points to the nearest galaxies on the projected plane which appears to provide a good measure of the bubbly character of the galaxy distribution. In a quantitative analysis of the CfA 'slice of the universe', a very good match is found between simulation and the real data for final average bubble radii of (13.5 + or - 1.5)/h Mpc with formal filling factor 1.0-1.5 or actual filling factor of 65-80 percent.

Ostriker, J. P.↗
NASA NTRS1989

Universal features of the equation of state of solids

A study of the energetics of solids leads to the conclusion that the equation of state for all classes of solids in compression can be expressed in terms of a universal function. The form of this universal function is determined by scaling experimental compression data for measured isotherms of a wide variety of solids. The equation of state is thus known (in the absence of phase transitions), if zero-pressure volume and isothermal compression and its pressure derivative are known. The discovery described in this paper has two immediate consequences: first, despite the well known differences in the microscopic energetics of the various classes of solids, there is a single equation of state for all classes in compression; and second, a new method is provided for analyzing measured isotherms and extrapolating high-pressure data from low-pressure (e.g. acoustic) data.

Vinet, Pascal↗
NASA NTRS1990

Extraterrestrial life in the universe

The possibility that life exists elsewhere in the universe, even in our own planetary system, has intrigued scientists, philosophers, and theologians for centuries. The spaceflight programs of NASA have provided much new information about our planetary neighbors and have put to rest some speculations about the existence of life on those planets or their satellites. However, there are still undetermined questions about the possibility of some form of life existing in the far distant past in our planetary system. Beyond our planetary system, the astronomical quest for scientific clues about life continues, largely via the radio telescope. Thus far there is no conclusive evidence. Here, some of the recent findings about our planetary neighbors are reviewed and the question about life elsewhere in the universe is addressed.

Graham, Robert W.↗
NASA NTRS1989

Large-scale cosmic microwave background anisotropies in isocurvature baryon open universe models

The large-angular-scale cosmic microwave background anisotropy is calculated in a low-density baryon-dominated universe with isocurvature primordial inhomogeneities. In models in which the initial power spectra of perturbations are steeper than white noise, predictions for the quadrupole moment of the anisotropy are found to be in conflict with existing observational limits, if the universe remained fully ionized and Compton drag inhibited growth of inhomogeneities until z = about 100. In order to lower the amplitude of the anisotropy, it is necessary to substantially prolong the duration of the growth phase of density perturbations, while smearing out fine-scale anisotropies, thereby requiring reionization to occur at a redshift smaller than 100, but larger than the redshift of the last scattering surface (in a reionized model).

Gorski, Krzysztof M.↗
NASA NTRS1989

Hubble Space Telescope - New view of an ancient universe

Scheduled for a March 1990 Shuttle launch, the Hubble Space Telescope (HST) will give astronomers a tool of unprecedented accuracy to observe the universe: an optically superb instrument free of the atmospheric turbulence, distortion, and brightness that plague all earthbound telescopes. The observatory will carry into orbit two cameras, a pair of spectrographs, a photometer, and fine guidance sensors optimized for astrometry. The diffraction limit for the 2.4-m aperture of the HST corresponds to 90 percent of the radiation from a point source falling within a circle of 0.1 arcsec angular radius at a wavelength of 633 nm. The 15-year mission will make observations in the ultraviolet as well as the optical spectral region, thus, widening the wavelength window to a range extending from the Lyman alpha wavelengnth of 122 nm to just about 2 microns. The observational program that awaits the HST will include the study of planetary atmospheres, in particular the search for aerosols; the study of globular star clusters within the Galaxy; and the determination of the present rate of expansion of the universe. The HST will achieve resolutions of 0.1 arcsec consistently, regardless of observation duration. The HST engineering challenge is also discussed.

Leckrone, David S.↗
NASA NTRS1989

Mapping the universe

Maps of the galaxy distribution in the nearby universe reveal large coherent structures. The extent of the largest features is limited only by the size of the survey. Voids with a density typically 20 percent of the mean and with diameters of 5000 km/s are present in every survey large enough to contain them. Many galaxies lie in thin sheet-like structures. The largest sheet detected so far is the 'Great Wall' with a minimum extent of 60/h Mpc x 170/h Mpc, where h is the Hubble constant in units of 100 km/s per Mpc. The frequent occurrence of these structures is one of several serious challenges to our current understanding of the origin and evolution of the large-scale distribution of matter in the universe.

Geller, Margaret J.↗
NASA NTRS1989

Dynamical evolution of domain walls in an expanding universe

Whenever the potential of a scalar field has two or more separated, degenerate minima, domain walls form as the universe cools. The evolution of the resulting network of domain walls is calculated for the case of two potential minima in two and three dimensions, including wall annihilation, crossing, and reconnection effects. The nature of the evolution is found to be largely independent of the rate at which the universe expands. Wall annihilation and reconnection occur almost as fast as causality allows, so that the horizon volume is 'swept clean' and contains, at any time, only about one, fairly smooth, wall. Quantitative statistics are given. The total area of wall per volume decreases as the first power of time. The relative slowness of the decrease and the smoothness of the wall on the horizon scale make it impossible for walls to both generate large-scale structure and be consistent with quadrupole microwave background anisotropy limits.

Press, William H.↗
NASA NTRS1990

Joint University Program for Air Transportation Research, 1989-1990

Research conducted during the academic year 1989-90 under the NASA/FAA sponsored Joint University Program for Air Transportation research is discussed. Completed works, status reports and annotated bibliographies are presented for research topics, which include navigation, guidance and control theory and practice, aircraft performance, human factors, and expert systems concepts applied to airport operations. An overview of the year's activities for each university is also presented.

Morrell, Frederick R.↗
NASA NTRS1990

Investigation of Air Transportation Technology at Ohio University, 1989-1990

The activities of the participants in the Joint University Program (JUP) at Ohio University are briefly surveyed. During 1989 to 1990, five topics received emphasis. A spectrum-efficient weather data uplink system was designed, constructed, and flight tested. An integrated Global Positioning System/Inertial Navigation System (GPS/INS) study continued, utilizing the Redundant strapdown Inertial Measurement Unit (IMU) on loan from NASA. The Ridge Regression theory was refined and applied to air navigation scenarios. System Identification theory was applied to GPS data to point the way to better understanding of the effects of Selective Availability on civilian users of this navigation system. An analysis of thought-related (electroencephalographic) signals for application to control of computer systems that could have significance in aiding paraplegics or for hands-off systems control in industrial or air traffic control areas was carried out.

Lilley, Robert W.↗
NASA NTRS1989

Jackson State University's Center for Spatial Data Research and Applications: New facilities and new paradigms

Jackson State University recently established the Center for Spatial Data Research and Applications, a Geographical Information System (GIS) and remote sensing laboratory. Taking advantage of new technologies and new directions in the spatial (geographic) sciences, JSU is building a Center of Excellence in Spatial Data Management. New opportunities for research, applications, and employment are emerging. GIS requires fundamental shifts and new demands in traditional computer science and geographic training. The Center is not merely another computer lab but is one setting the pace in a new applied frontier. GIS and its associated technologies are discussed. The Center's facilities are described. An ARC/INFO GIS runs on a Vax mainframe, with numerous workstations. Image processing packages include ELAS, LIPS, VICAR, and ERDAS. A host of hardware and software peripheral are used in support. Numerous projects are underway, such as the construction of a Gulf of Mexico environmental data base, development of AI in image processing, a land use dynamics study of metropolitan Jackson, and others. A new academic interdisciplinary program in Spatial Data Management is under development, combining courses in Geography and Computer Science. The broad range of JSU's GIS and remote sensing activities is addressed. The impacts on changing paradigms in the university and in the professional world conclude the discussion.

Davis, Bruce E.↗
NASA NTRS1991

Industry-university cooperation/research

The paper concentrates on the commercial development of space programs through cooperative research with the U.S. universities and industry. The origins of the programs are discussed, beginning with the Communication Satellite Act of 1963. The National Space Policy is outlined, and the creation of NASA's Office of Commercial Programs is emphasized, along with its Centers for the Commercial Development of Space. It is noted that the centers are consortia of university, industry, and government involved in commercial-space-technology database development and research and testing of potentially valuable products and services. The center titles, locations, and brief descriptions for such area of research as remote sensing, life sciences, materials processing, space power, space propulsion, materials and space structures, and automation and robotics centers are listed, along with some results of the programs.

Whitten, Raymond P.↗
NASA NTRS1991

Did the universe recombine?

The Zel'dovich-Sunyaev model-independent arguments for the existence of a neutral hydrogen phase is reviewed in light of new limits on the Compton y parameter from COBE. It is concluded that with baryon densities compatible with standard cosmological nucleosynthesis, the universe could have remained fully ionized throughout its history without producing a detectable spectral distortion. It is argued that it is unlikely that spectral observations of the cosmic microwave background will ever require the universe to have recombined for flat cosmologies.

Bartlett, James G.↗