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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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Preventive maintenance, calibration procedures, system verification, system operating procedures, systems software fundamentals, data base (program files), and patchboard layout are discussed.
Across the nightside of Venus, daily measurements from the PV Orbiter Ion Mass Spectrometer often indicate an ionosphere of relatively abundant concentration, with a composition characteristic of the dayside ionosphere. Such conditions are interspersed by other days on which the ionosphere appears to largely 'disappear' down to about 200 km, with ion concentrations at lower heights also much reduced. These characteristics, coupled with observations of strong day to night flows of O(+) in the upper ionosphere, support arguments that ion transport from the dayside is important for the maintenance of the nightside ionosphere. In the range 140-160 km, strong concentrations of O2(+) and NO(+) indicate that the ionization peak is at times composed of at least two prominent ion species. Nightside concentrations of O2(+) and NO(+) as large as 100,000 and 10,000/cu cm, respectively, appear to require sources in addition to that provided by transport. The most probable sources are considered briefly, and no satisfactory explanation is yet found for the observed NO(+) concentrations.
Alterations in the neuromuscular junction were observed in rats preceding loss of muscle mass. In view of the possibility that these alterations involve changes in the secretion of myotrophic agents by presynaptic motor neurons, an investigation was undertaken to characterize a neuronall factor which is thought to be involved in the initiation and maintenance of cholinergic synapses. This factor, which is secreted into the incubation medium by NG108-15 neuroblastoma x glioma hybrid cells, induces the aggregation of nicotinic acetylcholine receptors on primary cultures of rat hindlimb myotubes. Previous attempts to purify this factor failed. Extensive washing of the NG108-15 cells with hepes-buffered salt solution followed by short (4 hour) collection times resulted in the collection of incubation medium containing maximal aggregation activity with as little as 5 ug secreted protein per ml of fresh medium. A three-fold increase in specific activity was obtained after anion exchange chromatography.
The winter simulations of the GLAS climate model and the NCAR community climate model are used to examine the maintenance of the atmospheric kinetic energy. It is found that the kinetic energy is generated in the lower latitudes south of the maximum westerlies, transported northward and then, destroyed in the midlatitudes north of the maximum westerlies. Therefore, the atmospheric kinetic energy is maintained by the counterbalance between the divergence (convergence) of kinetic energy flux and generation (destruction) of kinetic energy in lower (middle) latitudes.
The Space Station crew will be a critical resource for economical operation of science and commercial payloads. Core station housekeeping and maintenance functions should be provided in a manner that requires a minimum of crew interaction. This paper outlines a prospective functional architecture for allocation of autonomous and automated control of these functions and discusses implementation issues arising from safety of manned operations, integration test requirements, and evolution of future station capabilities.
A system of computer programs has been developed to model general three-dimensional surfaces. Surfaces are modeled as sets of parametric bicubic patches. There are also capabilities to transform coordinate to compute mesh/surface intersection normals, and to format input data for a transonic potential flow analysis. A graphical display of surface models and intersection normals is available. There are additional capabilities to regulate point spacing on input curves and to compute surface intersection curves. Internal details of the implementation of this system are explained, and maintenance procedures are specified.
Living human cells require attachment to a suitable surface and special culture conditions in order to grow. These requirements are modified and amplified when cells are taken into a weightless environment. Special handling and maintenance systems are required for routine laboratory procedures conducted in the Orbiter and in the Spacelab. Methods were developed to maintain cells in special incubators designed for the Orbiter middeck, however, electrophoresis and other experiments require cells to be harvested off of the culture substrate before they can be processed or used. The cell transport assembly (CTA) was flown on STS-8, and results show that improvements are required to maintain adequate numbers of cells in this device longer than 48 hours. The life sciences middeck centrifuge probably can be used, but modifications will be required to transfer cells from the CTA and keep the cells sterile. Automated systems such as the Skylab SO-15 flight hardware and crew operated systems are being evaluated for use on the Space Shuttle, Spacelab, and Space Station research modules.
The preparation of 30 controlled documents for each flight of the Space Shuttle involves 90 people in processing 200 or 300 changes to existing checklists, and building new procedures. A prototype system is discussed which stores and displays those precise sets of instructions, which include rationale and change history, by using readily available hardware. It provides a simple method of structuring the data in a form for easy undertanding and maintenance.
With the goal of trying to understand what software maintainers do, talking aloud, video taped protocols with four expert maintainers were conducted as they were actively engaged in the process of enhancing a relatively small, interactive database program. The subjects exhibited a number of different types of information gathering strategies. Underlying these patterns of behavior, however, was the use of expectations about what should be seen in the program under examination. These expectations were generated on the basis of knowledge previously acquired as to the goals and programming plans that are typically employed in realizing interactive database programs. Thus, while the experts seemed to posses adequate programming knowledge, their actual code patches violated a basic principle of program structure. This failure by the programmers was attributed to ineffective program documentation. Suggestions for changes in the content of program documentation that should better facilitate software maintenance are presented.
A laser photodetector station is used for detecting the arrival of a projectile at a specific point along a ballistic range. The system can be employed on either an open or evacuated range, with small projectiles, and at hypervelocities. The setup procedures, maintenance, and system components are described.
Source Management Utility (SMU) computer program is tool to manage development and maintenance of computer software. Its purpose to control organization of configured data sets containing source, object, and load-module files. Written in PL/1 and assembler.
The Health Maintenance Facility (HMF) requirements which enable/enhance manned Mars missions (MMMs) are addressed. It does not attempt to resolve any issues that may affect the feasibility of any given element in the HMF. Reference is made to current work being conducted in the design of the space station HMF. The HMF requirements are discussed within the context of two distinctly different scenarios: HMF as part of the Mars surface infrastructure, and HMF as part of the nine months translation from low Earth orbit to Mars orbit. Requirements for an HMF are provided, and a concept of HMF is shown.
The Nickel-Cadmium Battery Expert System (NICBES) is an expert system for fault diagnosis and advice of the nickel-cadmium batteries found in the Hubble Space Telescope (HST). The system application and security, equipment environment, and the program maintenance procedures are examined.
An analytical approach is presented which was developed and implemented at MSFC specifically for the Space Telescope Program to provide comparisons of critical item failures, system downstates, on-orbit servicing versus return for ground maintenance, overall system downtime, and to obtain a measure of expected uptime for science functions.
The goal is to define and establish Space Assembly, Maintenance, and Servicing (SAMS) capabilities to meet requirements for improved space systems. Consolidated requirements, hardware/tool concepts, systems analysis, related studies interaction, and schedule/milestones are outlined. This presentation is represented by charts and figures only.
A Health Maintenance Facility is currently under development for space station application which will provide capabilities equivalent to those found on Earth. This final report addresses the study of alternate means of diagnosis and evaluation of impaired tissue perfusion in a microgravity environment. Chemical data variables related to the dysfunction and the sensors required to measure these variables are reviewed. A technology survey outlines the ability of existing systems to meet these requirements. How the candidate sensing system was subjected to rigorous testing is explored to determine its suitability. Recommendations for follow-on activities are included that would make the commercial system more appropriate for space station applications.
The Spacecraft Assembly, Maintenance, and Servicing Study (SAMSS) is an effort to define and verify the most cost effective approach to spacecraft servicing, as a alternative to replacement, in the 1990's and beyond. The intent of the study is to assess the servicing of satellites in all orbit regimes. Elements of a space servicing infrastructure are developed and cost estimates are generated. Readiness is assessed and proof of concept demonstrations are identified. Cryogenic fuel resupply is discussed.
A series of intelligent tutoring systems, or intelligent maintenance simulators, is being developed based on expert and novice problem solving data. A graded series of authentic troubleshooting problems provides the curriculum, and adaptive instructional treatments foster active learning in trainees who engage in extensive fault isolation practice and thus in conditionalizing what they know. A proof of concept training study involving human tutoring was conducted as a precursor to the computer tutors to assess this integrated, problem based approach to task analysis and instruction. Statistically significant improvements in apprentice technicians' troubleshooting efficiency were achieved after approximately six hours of training.