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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 1,531 records · Page 85

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NASA NTRS1984

Mars geoscience/climatology orbiter low cost mission operations

It will not be possible to support the multiple planetary missions of the magnitude and order of previous missions on the basis of foreseeable NASA funding. It is, therefore, necessary to seek innovative means for accomplishing the goals of planetary exploration with modestly allocated resources. In this connection, a Core Program set of planetary exploration missions has been recommended. Attention is given to a Mission Operations design overview which is based on the Mars Geoscience/Climatology Orbiter Phase-A study performed during spring of 1983.

Erickson, K. D.↗

NASA NTRS1982

The International Halley Watch

The International Halley Watch (IHW) is a program designed to promote cooperation, standardization, and archival documentation in all phases of study of Comet Halley during its 1985-86 apparition. Discipline Specialists have been selected to create cooperative nets of ground-based observers encompassing seven different technical areas and to coordinate the observations and publication of results in each. The IHW will promote cooperation among ground-based and space studies of Comet Halley wherever reasonable and feasible. More specifically, the IHW will make ephemerides from the astrometric net available to any country flying a deep space mission. It will coordinate special Halley Watch Days with the arrival dates of space probes or periods of observation from earth orbit. And the IHW will provide a permanent archive in published form of all scientific observations of Comet Halley.

Rahe, J.↗

NASA NTRS1984

Turbulent transport and length scale measurement experiments with comfined coaxial jets

A three phase experimental study of mixing downstream of swirling and nonswirling confined coaxial jets was conducted to obtain data for the evaluation and improvement of turbulent transport models currently employed in a variety of computational procedures. The present effort was directed toward the acquisition of length scale and dissipation rate data that provide more accurate inlet boundary conditions for the computational procedures and a data base to evaluate the turbulent transport models in the near jet region where recirculation does not occur, and the acquisition of mass and momentum turbulent transport data for a nonswirling flow condition with a blunt inner jet inlet configuration rather than the tapered inner jet inlet. A measurement technique, generally used to obtain approximate integral length and microscales of turbulence and dissipation rates, was computerized. Results showed the dissipation rate varied by 2 1/2 orders of magnitude across the inlet plane, by 2 orders of magnitude 51 mm from the inlet plane, and by 1 order of magnitude at 102 mm from the inlet plane for a nonswirling flow test conditions.

Johnson, B. V.↗

NASA NTRS1984

Evaluation of high temperature structural adhesives for extended service

High temperature stable adhesive systems were evaluated for potential Supersonic Cruise Research (SCR) vehicle applications. The program was divided into two major phases: Phase I 'Adhesive Screening' evaluated eleven selected polyimide (PI) and polyphenylquinoxaline (PPQ) adhesive resins using eight different titanium (6Al-4V) adherend surface preparations; Phase II 'Adhesive Optimization and Characterization' extensively evaluated two adhesive systems, selected from Phase I studies, for chemical characterization and environmental durability. The adhesive systems which exhibited superior thermal and environmental bond properties were LARC-TPI polyimide and polyphenylquinoxaline both developed at NASA Langley. The latter adhesive system did develop bond failures at extended thermal aging due primarily to incompatibility between the surface preparation and the polymer. However, this study did demonstrate that suitable adhesive systems are available for extended supersonic cruise vehicle design applications.

Hendricks, C. L.↗

NASA NTRS1986

Nucleation experiments in a microgravity environment

A simple experimental apparatus is described in which a wide variety of vapor phase nucleation studies of refractory materials could be performed aboard NASA's KC-135 Research Aircraft. The chief advantage of a microgravity environment for these studies is the expected absence of thermally driven convective motions in the gas. The absence of convection leads to much more accurate knowledge of both the temperature distribution in the system and the time evolution of the refractory vapor concentration as a function of distance from the crucible.The evolution of the apparatus will be described as more experience is gained with the microgravity environment. Such experiments will be used to prepare for similar ones carried out aboard either the shuttle or Space Station where considerably longer duration experiments are possible.

Nuth, J. A.↗

NASA NTRS1986

Transportation

A summary of tether transportation is given. Four steps were used over a period of time. First, theoretical engineering feasibility and technology requirements were determined. Then the survivors of that effort went into step two in the analysis of promising candidates. Those survivors went into the third phase which is engineering design and cost benefits. Survivors entered into the demonstration mission definition phase. Transportation studies have covered two kinds of deployments. First, steady state deployment was studied. Like the TSS, it's nearly vertical. It takes a long time to deploy and involves relatively high tether tension. Secondly, dynamic deployment was studied. Deployment started in an almost horizontal direction under a very shallow angle which allows a high deployment rate under very low tension. Momentum transfer here occurs by libration. Specific payloads were used to study tethered transportation benefits. Four transportation concepts were studied with regard to cost benefits. A tethered orbiter deboost from the space station, an OTV boost up from the Space Station, a science platform on a tether with a possible micro-g lab moving in between platform and station, and a tethered boost of payloads fromthe orbiter are the four concepts. These benefits are examined in detail.

Vontiesenhausen, G.↗

NASA NTRS1985

Stratification of the extended atmosphere of the Wolf-Rayet component of V444 Cygni

Ultraviolet spectra covering both eclipses of V444 Cygni have been obtained. Longward of 1570 angstroms, the continuum brightness showed essentially the same variation seen in the optical (at 4244 angstroms). Striking atmospheric eclipses of up to 0.7 mag in depth were detected, however, in individual strong lines as well as over large ranges of the continuum shortward of 1500 angstroms. IUE data are used to estimate the degree of interstellar extinction and terminal expansion velocity of the system and to study the phase dependence of the continuum and line absorptions.

Eaton, J. A.↗

NASA NTRS1984

AXAF - A major spaceborne X-ray observatory

Attention is given to the design configuration and performance requirements of the Advanced X-ray Astrophysics Facility, as established by Phase A study results, noting the conceptual apprach to instrument accommodation by means of a focal plane assembly. Conceptually, the various instruments incorporated are modular in design, so that they may be replaced in orbit using standard interfaces. The instruments in question are high and moderate resolution imagers, a high resolution dispersive spectrometer, a moderate resolution spectrometer, and a focal plane polarimeter.

Wyman, C. L.↗

NASA NTRS1986

Table Mountain Observatory support to other programs

Over 20 asteroids were observed photometrically for period determinations and phase relation studies. These included 1036 Ganymed, the largest Mars-crossing asteroid known, and 1627 Ivar, an earth-approaching asteroid which is a potential space mission target. Doppler images of P/Halley from TMO were obtained. Initial testing of the JPL/TMO CCD camera system has supported by imaging P/Giacobini-Zinner and P/Halley.

Alan W. Harris↗

NASA NTRS1986

Off-line processing of ERS-1 synthetic aperture radar data with high precision and high throughput

The first European remote sensing satellite ERS-1 will be launched by the European Space Agency (ESA) in 1989. The expected lifetime is two to three years. The spacecraft sensors will primarily support ocean investigations and to a limited extent also land applications. Prime sensor is the Active Microwave Instrumentation (AMI) operating in C-Band either as Synthetic Aperture Radar (SAR) or as Wave-Scatterometer and simultaneously as Wind-Scatterometer. In Europe there will be two distinct types of processing for ERS-1 SAR data, Fast Delivery Processing and Precision Processing. Fast Delivery Proceessing will be carried out at the ground stations and up to three Fast Delivery products per pass will be delivered to end users via satellite within three hours after data acquisition. Precision Processing will be carried out in delayed time and products will not be generated until several days or weeks after data acquisition. However, a wide range of products will be generated by several Processing and Archiving Facilities (PAF) in a joint effort coordinated by ESA. The German Remote Sensing Data Center (Deutsches Fernerkundungsdatenzentrum DFD) will develop and operate one of these facilities. The related activities include the acquisition, processing and evaluation of such data for scientific, public and commercial users. Based on this experience the German Remote Sensing Data Center is presently performing a Phase-B study regarding the development of a SAR processor for ERS-1. The conceptual design of this processing facility is briefly outlined.

Gredel, J.↗

NASA NTRS1987

Six component robotic force-torque sensor

The results of a two-phase contract studying the feasibility of a miniaturized six component force-torque sensor and development of a working laboratory system were described. The principle of operation is based upon using ultrasonic pulse-echo ranging to determine the position of ultrasonic reflectors attached to a metal or ceramic cover plate. Because of the small size of the sensor, this technology may have application in robotics, to sense forces and torques at the finger tip of a robotic end effector. Descriptions are included of laboratory experiments evaluating materials and techniques for sensor fabrication and of the development of support electronics for data acquisition, computer interface, and operator display.

Grahn, Allen R.↗

NASA NTRS1987

An Investigation of the Dynamic Response of Spur Gear Teeth with Moving Loads

Two concepts relating to gear dynamics were studied. The first phase of the analysis involved the study of the effect of the speed of a moving load on the dynamic deflections of a gear tooth. A single spur gear tooth modelled using finite elements was subjected to moving loads with variable velocities. The tooth tip deflection time histories were plotted, from which it was seen that the tooth tip deflection consisted of a quasistatic response with an oscillatory response superimposed on it whose amplitude was dependent on the type of load engagement. Including the rim in the analysis added flexibility to the model but did not change the general behavior of the system. The second part of the analysis involved an investigation to determine the effect on the dynamic response of the inertia of the gear tooth. A simplified analysis using meshing cantilever beams was used. In one case, the beams were assumed massless. In the other, the mass (inertia) of the beams was included. From this analysis it was found that the inertia of the tooth did not affect the dynamic response of meshing cantilever beams.

Passerello, C. E.↗

NASA NTRS1987

Concerning the relationship between evapotranspiration and soil moisture

The relationship between the evapotranspiration and soil moisture during the drying, supply-limited phase is studied. A second scaling parameter, based on the evapotranspirational supply and demand concept of Federer (1982), is defined; the parameter, referred to as the threshold evapotranspiration, occurs in vegetation-covered surfaces just before leaf stomata close and when surface tension restricts moisture release from bare soil pores. A simple model for evapotranspiration is proposed. The effects of natural soil heterogeneities on evapotranspiration computed from the model are investigated. It is observed that the natural variability in soil moisture, caused by the heterogeneities, alters the relationship between regional evapotranspiration and the area average soil moisture.

Wetzel, Peter J.↗

NASA NTRS1988

Mg II line profiles of the Mira S Carinae

High-dispersion IUE observations obtained to investigate the evolution of the shock structure of the Mira S Carinae (S Car) produced, despite very limited phase coverage, a set of five spectra of the Mg II h and k lines. There is significant emission from both the h and k lines at velocities of -150 km/sec relative to the stellar photosphere. The h-to-k ratio of the Mg II doublet remains below the theoretically predicated values of 2:1 to 1:1, and shows a smooth dependence on the optical phase. Archival studies of other Miras (e.g., R Car) indicate that S Car is not unique in possessing unusual and highly variable Mg II h and k line profiles.

Brugel, Edward W.↗

NASA NTRS1987

Definition of a space transportation systems cargo element (Shuttle-C). Orientation

The Martin Marietta Shuttle-C project organization has been tailored to fit the tasks required for the Phase B study. Lead responsibilities have been assigned for Program Control, Safety, Reliability, and Quality Assurance (SR and QA); Systems Engineering and Integration (SE and I); Design and Analysis; Production and Test; and Operations. Details of the Performance Review and Orientation Program of November 1987 are given.

Source record↗

NASA NTRS1988

Design concept for the Flight Telerobotic Servicer (FITS)

NASA has just completed an in-house Phase B Study (one of three studies) for the preliminary definition of a teleoperated robotic device that will be used on the National Space Transportation System (NSTS) and the Space Station to assist the astronauts in the performance of assembly, maintenance, servicing, and inspection tasks. This device, the Flight Telerobotic Servicer (FTS), will become a permanent element on the Space Station. Although it is primarily a teleoperated device, the FTS is being designed to grow and evolve to higher states of autonomy. Eventually, it will be capable of working from the Orbital Maneuvering Vehicle (OMV) to service free-flying spacecraft at great distances from the Space Station. A version of the FTS could also be resident on the large space platforms that are part of the Space Station Program.

Andary, J. F.↗

NASA NTRS1988

MFE/Magnolia - A joint CNES/NASA mission for the earth magnetic field investigation

The joint phase B study in the CNES/NASA MFE/Magnolia mission to study the earth's magnetic field are reported. The scientific objectives are summarized and the respective responsibilities of NASA and CNES are outlined. The MFE/Magnolia structure and power systems, mass and power budgets, attitude control system, instrument platform and boom, tape recorders, rf system, propellant system, and scientific instruments are described.

Runavot, Josette↗

NASA NTRS1988

Numerical model-based diagnostic study of the rapid development phase of the Presidents' Day cyclone

A mesoscale model simulation of the Presidents' Day cyclone at 1200 GMT 18 February 1979 is presented which captures the upper-tropospheric intrusion of stratospheric air upstream of the East Coast and subsequent development of the surface cyclone. The model simulation is then used to examine the descent of the stratospheric air mass and the interaction of this air mass with a lower-tropospheric potential vorticity maximum associated with an inverted trough and coastal front along the East Coast. The model is also used to examine the processes that contribute to the rapid decrease of sea-level pressure and increase in lower-tropospheric cyclonic vorticity during the explosive development phase of the cyclone.

Whitaker, Jeffrey S.↗