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NASA NTRS1991

A proposed time transfer experiment between the USA and the South Pacific

This paper describes the concept, architecture and preliminary details of an experiment directc<l towards providing continuous Ultra High Precision (UHP) time transfer between Washington, DC; Salisbury, SA Australia; Orroral Valley, ACT Australia; arid Lower Hutt, New Zealand. It further describes a proposed method of distributing UTC(USNO) at a high level of precision to passive users over a broad area of the South Pacific. The concept is based on active two-way satellite time transfer from the United States Naval Observatory (USNO) to the proposed USNO Master Clock West (MCW) in Wahiwa, HI USA at the 1 nanosecond level using active satellite two-way time transfer augmented by Precise Positioning Service (PPS) of the Global Positioning System (GPS). MCW would act as an intermediate transfer/reference station, again linked to Salisbury at the 1 nanosecond level using active satellite two-way time transfer augmented by PPS GPS. From this point, time would bc distributed within the region by two methods. The first is an existing TV line sync system using an Australian communications satellite (AUSSAT K1) which is useful to the 20 nanosecond level. The second approach is RF ranging and multilateration between Salisbury, Orroral Observatory, Lower Hutt and the AUSSAT B1 and B2 to be launched in 1992. Orroral Observatory will provide precise laser ranging to the AUSSAT B1/B2 retro reflectors which will reduce ephemeris related time transfer errors to below 1 nanosecond. The corrected position will be transmitted by both the time transfer modem and the existing TV line sync dissemination process. Multilateration has the advantage of being an all weather approach and when used with the laser ranging technique will provide a precise measurement of the propagation path delays. This will result in time transfer performance levels on the order of 10 nanoseconds to passive users in both Australia and New Zealand.

John Luck↗

NASA NTRS1991

Spectral signature of oxidized pyroxenes - Implications to remote sensing of terrestrial planets

The effect of the structural Fe(3+) or disseminated ferric oxides in oxidized ferromagnesian silicates on the reflectance spectral profiles of the remnant Fe(2+) ions in oxidized silicates was investigated. Results of spectral measurements in the visible NIR region, performed on several well-characterized pyroxenes representative of different structural types and compositions, were correlated with data obtained from the Mossbauer spectra of the oxidation products. The measurements made it possible to determine the relative proportions of Fe(2+) and Fe(3+) ions present in the oxidized pyroxenes and provided information on the amorphous ferric oxide phases present in the oxidation products. The results also suggest a mechanism for producing the nanophase hematite popularly considered to be responsible for the features observed around 0.62 and 0.87 micron in the remotely sensed spectra of Mars.

Straub, D'arcy W.↗

NASA NTRS1991

Overview of the Astrophysics Data System

The Astrophysics Division of NASA has built a geographically and logically distributed heterogeneous information system for the dissemination and coordinated multispectral analysis of data from astrophysics missions. The Astrophysics Data System (ADS) is a truly distributed system in which the data and the required processing are physically distributed. To accommodate the anticipated growth and changes in both requirements and technology, the ADS employs a server/client architecture which allows services and data to be added or replaced without having to change the basic architecture or interfaces. Current datasets accessible through the system include all the tabular astronomical data available at each of six existing astrophysics data centers. Additional data nodes, at both NASA data centers and academic institutions, will be added shortly. The future evolution of the system will be driven in large part by user services mounted both by the ADS project itself and by members of the astrophysics community.

Good, John C.↗

NASA NTRS1990

Prelaunch processing scientific payloads since Challenger - Lessons learned exercise

The 'lessons learned' process that follows each NASA payload-processing operation is described with attention given to the development of a knowledge base from the results. The process is based on the subjective evaluation of operations problems by test-team members following a mission. The lessons learned from four Space Shuttle missions - STS-26R, -29R, -30R, and -30 - are examined with categorizations of incidents which is based on operational, documentation, hardware, and software categories. Recommendations for ways to address the incidents are categorized similarly, with operational categories such as admonitory, documentation modifications, and support changes. A basic numerical dataset is developed based on the results, and the data show that STS-26R had the highest number of incidents. The process is found to be an effective educational tool in payload-processing operations because it disseminates key individual experiences.

Schuiling, R. L.↗

NASA NTRS1992

Quantitative image processing in fluid mechanics

The current status of digital image processing in fluid flow research is reviewed. In particular, attention is given to a comprehensive approach to the extraction of quantitative data from multivariate databases and examples of recent developments. The discussion covers numerical simulations and experiments, data processing, generation and dissemination of knowledge, traditional image processing, hybrid processing, fluid flow vector field topology, and isosurface analysis using Marching Cubes.

Hesselink, Lambertus↗

NASA NTRS1993

A synopsis of test results and knowledge gained from the Phase-0 CSI evolutionary model

The Phase-0 CSI Evolutionary Model (CEM) is a testbed for the study of space platform global line-of-sight (LOS) pointing. Now that the tests have been completed, a summary of hardware and closed-loop test experiences is necessary to insure a timely dissemination of the knowledge gained. The testbed is described and modeling experiences are presented followed by a summary of the research performed by various investigators. Some early lessons on implementing the closed-loop controllers are described with particular emphasis on real-time computing requirements. A summary of closed-loop studies and a synopsis of test results are presented. Plans for evolving the CEM from phase 0 to phases 1 and 2 are also described. Subsequently, a summary of knowledge gained from the design and testing of the Phase-0 CEM is made.

Belvin, W. Keith↗

NASA NTRS1992

The AGARD tip research agenda for Scientific and Technical Information (STI)

The Research Agenda contains three themes: information management, provision of information, and access to information. Provision of information is further divided into two subordinate themes, dissemination and bibliographic control; access to information is also further divided into two subordinate themes, barriers and equity and networking. Each theme or sub-theme was examined from four possible aspects, namely, human resources, quality assurance, cost, and technology. It was concluded that, in fact, a theme or sub-theme need not contain all four aspects.

Blados, Walter R.↗

NASA NTRS1992

Flight Testing

It is considered by the Flight Mechanics Panel of AGARD as vitally important that the NATO flight test community meet regularly so that new techniques for flight test, instrumentation and data analysis and lessons learned from past and on-going programs be disseminated to ensure that safe efficient cost-effective and timely testing is accomplished. There are many new systems being tested or planned for testing in the near future. These include programmable signal processor radars, integrated flight, fire and propulsion control systems, thrust vectoring, low observable technologies, multifunction pilot displays and multisensor integration. Acquisition and processing of large quantities of avionics multiplex data are challenges that must be met. There is a need for greater use of simulators and other hardware-in-the-loop ground test facilities.

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NASA NTRS1992

Einstein Slew Survey: Data analysis innovations

Several new methods were needed in order to make the Einstein Slew X-ray Sky Survey. The innovations which enabled the Slew Survey to be done are summarized. These methods included experimental approach to large projects, parallel processing on a LAN, percolation source detection, minimum action identifications, and rapid dissemination of the whole data base.

Elvis, Martin S.↗

NASA NTRS1991

MIT Space Engineering Research Center testbed programs

The Space Engineering Research Center (SERC) at M.I.T., started in July 1988, has completed two and one-half years of research. This Semi-Annual Report presents annotated viewgraph material presented at the January 1991 Steering Committee and Technical Representative Review. The objective of the Space Engineering Research Center is to develop and disseminate a unified technology of controlled structures. There has been continued evolution of the concept of intelligent structures (including in this past year the first successful embedding of a microelectronic component into a structural element).

Crawley, Edward F.↗

NASA NTRS1993

Thermal protection system of the Space Shuttle's orbiter

It is the teams view that there is a general lack of awareness of orbiter tile susceptibility to damage by debris - the same applies to the care and critical nature of the shuttle elements and operations process so necessary to minimizing damaging debris - it is essential that all involved employees, both government and contractor, understand that minuscule loose objects or materials coming off the elements will most likely cause some tile damage at the speed encountered during ascent. It is recommended that descriptive material, photos, video tape, debris samples and other appropriate matter be assembled and provided to the proper organizations for dissemination to their employees - it should emphasize that the tiles perform outstanding in their debris-free design environment; but, are extremely sensitive to small particle damage.

Jones, Frank E.↗

NASA NTRS1993

Newly available technologies present expanding opportunities for scientific and technical information exchange

The potential for expanded communication among researchers, scholars, and students is supported by growth in the capabilities for electronic communication as well as expanding access to various forms of electronic interchange and computing capabilities. Research supported by the National Aeronautics and Space Administration points to a future where workstations with audio and video monitors and screen-sharing protocols are used to support collaborations with colleagues located throughout the world. Instruments and sensors all over the world will produce data streams that will be brought together and analyzed to produce new findings, which in turn can be distributed electronically. New forms of electronic journals will emerge and provide opportunities for researchers and scientists to electronically and interactively exchange information in a wide range of structures and formats. Ultimately, the wide-scale use of these technologies in the dissemination of research results and the stimulation of collegial dialogue will change the way we represent and express our knowledge of the world. A new paradigm will evolve-perhaps a truly worldwide 'invisible college'.

Tolzman, Jean M.↗

NASA NTRS1992

Technology utilization and American competitiveness

This session of discussions reports on two sides of the technology transfer issue. The speakers are representatives of the aluminum industry (Alcoa Aluminum) and the National Aeronautics and Space Administration, Office of Commercial Programs. They discuss what technology transfer means, what NASA does for industry, and how information is disseminated.

Penaranda, Frank↗

NASA NTRS1990

Coordinating Council. First Meeting: NASA/RECON database

A Council of NASA Headquarters, American Institute of Aeronautics and Astronautics (AIAA), and the NASA Scientific and Technical Information (STI) Facility management met (1) to review and discuss issues of NASA concern, and (2) to promote new and better ways to collect and disseminate scientific and technical information. Topics mentioned for study and discussion at subsequent meetings included the pros and cons of transferring the NASA/RECON database to the commercial sector, the quality of the database, and developing ways to increase foreign acquisitions. The input systems at AIAA and the STI Facility were described. Also discussed were the proposed RECON II retrieval system, the transmittal of document orders received by the Facility and sent to AIAA, and the handling of multimedia input by the Departments of Defense and Commerce. A second meeting was scheduled for six weeks later to discuss database quality and international foreign input.

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NASA NTRS1992

International organisation of ocean programs: Making a virtue of necessity

When faced with the needs of climate prediction, a sharp contrast is revealed between existing networks for the observation of the atmosphere and for the ocean. Even the largest and longest-serving ocean data networks were created for their value to a specific user (usually with a defence, fishing or other maritime purpose) and the major compilations of historical data have needed extensive scientific input to reconcile the differences and deficiencies of the various sources. Vast amounts of such data remain inaccessible or unusable. Observations for research purposes have been generally short lived and funded on the basis of single initiatives. Even major programs such as FGGE, TOGA and WOCE have been driven by the dedicated interest of a surprisingly small number of individuals, and have been funded from a wide variety of temporary allocations. Recognising the global scale of ocean observations needed for climate research, international cooperation and coordination is an unavoidable necessity, resulting in the creation of such bodies as the Committee for Climatic Changes and the Ocean (CCCO), with the tasks of: (1) defining the scientific elements of research and ocean observation which meet the needs of climate prediction and amelioration; (2) translating these elements into terms of programs, projects or requirements that can be understood and participated in by individual nations and marine agencies; and (3) the sponsorship of specialist groups to facilitate the definition of research programs, the implementation of cooperative international activity and the dissemination of results.

Mcewan, Angus↗

NASA NTRS1992

Modeling and analysis tools

The topics covered are presented in viewgraph form and include the following: the effect of the Mars environment on systems; the design of models and modeling tools; space environment interaction information dissemination; tools used in the development and validation of models; Space Exploration Initiative planning; and systems integration.

Jongeward, Gary↗

NASA NTRS1992

Opening remarks

The year's accomplishments at the onset of the yearly NAPEX meetings are reviewed. Therefore, I will present the last year's accomplishments and the plans for the next year. The studies supported by the Propagation Program during the last year are listed: OLYMPUS data collection and analysis; the ACTS Propagation Program; low elevation angle 11-GHz measurements; satellite broadcast and mobile studies; radiometric techniques; propagation models database; NASA Reference Publication 1274; CCIR activities; fade detection and compensation; rain rate measurements; and information dissemination.

Davarian, Faramaz↗

NASA NTRS1991

Astrophysics science operations in the Great Observatories era

Plans for Astrophysics science operations during the decade of the nineties are described from the point of view of a scientist who wishes to make a space-borne astronomical observation or to use archival astronomical data. 'Science Operations' include the following: proposal preparation, observation planning and execution, data collection, data processing and analysis, and dissemination of results. For each of these areas of science operations, we derive technology requirements for the next ten to twenty years. The scientist will be able to use a variety of services and infrastructure, including the 'Astrophysics Data System.' The current status and plans for these science operations services are described.

Riegler, Guenter R.↗