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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Compositional trends and cooling rates of group IVB iron meteorites

It is found, on the basis of new neutron activation data for group IVB, that log-element - log-Ni trends are best understood in terms of core formation and fractional crytstallizaion. The limited compositional range found in gorup IVB is thought to reflect the fact that, owing to the low concentrations of S, P, and C and the high concentration of Ni, the k sub x (the solid/liquid partition ratio) values are closer to unity than are those in other magmatic groups. Mean volatile abundances in group IVB are significantly lower than those found in any group of chondritic meteorites, indicating that these low abundances are not entirely the result of nebular processes and that planetary outgassing was also involved.

Rasmussen, K. L.↗
NASA NTRS1986

Error propagation in a digital avionic processor: A simulation-based study

An experimental analysis to study error propagation from the gate to the chip level is described. The target system is the CPU in the Bendix BDX-930, an avionic miniprocessor. Error activity data for the study was collected via a gate-level simulation. A family of distributions to characterize the error propagation, both within the chip and at the pins, was then generated. Based on these distributions, measures of error propagation and severity were defined. The analysis quantifies the dependency of the measured error propagation on the location of the fault and the type of instruction/microinstruction executed.

Lomelino, D.↗
NASA NTRS1986

Effects of the low Earth orbital environment on spacecraft materials

It is evident from space flights during the last three years that the low Earth orbital (LEO) environment interacts with spacecraft surfaces in significant ways. One manifestation of these interactions is recession of, in particular, organic-polymer-based surfaces presumably due to oxidation by atomic oxygen, the major component of the LEO environment. Three experiments have been conducted on Space Shuttle flights 5, 8 and 41-G to measure reaction rates and the effects of various parameters on reaction rates. Surface recession on these flights indicates reaction efficiencies approximately 3 x 10(-24) cu cm/atoms for unfilled organic polymers. Of the metals, silver and osmium are very reactive. Effects on spacecraft or experiment surfaces can be evaluated using the derived reaction efficiencies and a definition of the total exposure to atomic oxygen. This exposure is obtained using an ambient density model, solar activity data and spacecraft parameters of altitude, attitude and operational date. Oxygen flux on a given surface is obtained from the ambient density and spacecraft velocity and can then be integrated to provide the total exposure or fluence. Such information can be generated using simple computational programs and can be converted to various formats. Overall, the extent of damage is strongly dependent on the type of surface and total exposure time.

Leger, L. J.↗
NASA NTRS1986

A nonmagmatic origin of group-IIE iron meteorites

New neutron activation data on 10 elements in 12 IIE and IIE-related irons lead to a reclassification of several irons. Seymchan and Lonaconing are removed from IIE, and Leshan added. Four IIE members are designated IIE-An to call attention to some anomalous properties. The eight normal IIE members define element-Ni trends generally similar to those in the nonmagmatic group IAB; the small negative slopes on W-Ni and Ir-Ni diagrams are strongly indicative of a nonmagmatic origin of the IIE irons. It is proposed that IIE irons like IAB irons originated as individual pools of impact-produced melt in the near-surface region of a chondritic parent body. The positive As-Ni and Au-Ni trends are the only evidence suggesting fractional crystallization, but their slopes are lower than those in magmatic group IIIAB, and only slightly higher than those of Cu and Sb in IAB. It is suggested that the S and C contents of the IIE precursor materials were much lower than those of the IAB precursors, thus higher temperatures were required to generate enough metallic melt to segregate into pools. These higher temperatures are also reflected in the nonchondritic compositions of the silicate inclusions.

Wasson, J. T.↗
NASA NTRS1986

A modeling analysis program for the JPL Table Mountain Io sodium cloud data

Progress and achievements in the second year are discussed in three main areas: (1) data quality review of the 1981 Region B/C images; (2) data processing activities; and (3) modeling activities. The data quality review revealed that almost all 1981 Region B/C images are of sufficient quality to be valuable in the analyses of the JPL data set. In the second area, the major milestone reached was the successful development and application of complex image-processing software required to render the original image data suitable for modeling analysis studies. In the third area, the lifetime description of sodium atoms in the planet magnetosphere was improved in the model to include the offset dipole nature of the magnetic field as well as an east-west electric field. These improvements are important in properly representing the basic morphology as well as the east-west asymmetries of the sodium cloud.

Smyth, W. H.↗
NASA NTRS1986

Rotational modulation and flares on RS CVn and BY Dra-type stars. I - Photometry and spot models for BY Dra, AU Mic, AR Lac, II Peg and V 711 Tau (= HR 1099)

Multicolor wide-band photometry of five active stars is presented. The observations were carried out at several places before, during and after the period of IUE observations for the purpose of determining the location, sizes, and evolution of photospheric spots at the time when chromospheric, transition region, and coronal activity data were obtained from UV and radio observations. II Peg, BY Dra, and AU Mic show fairly stable quasi-sinusoidal light curves, while AR Lac and V 711 Tau show double-peaked light curves. For V 711 Tau, a remarkable evolution of the spotted area extent and/or longitude distribution is found. Small, but definite color variations that are consistent with the cool spot hypothesis have also been detected for BY Dra, II Peg and V 711 Tau.

Rodono, M.↗
NASA NTRS1987

Distinct meteoroid families identified on the lunar seismograms

The meteoroid impact-seismic activity data recorded by the Apollo lunar seismic network is examined. The study investigates the difference in temporal distribution between large and small impacts, clustering of impacts in a two-dimensional space of the time of the year and the time of the month, and the relationship of these observations with terrestrial observations. Several distinct families of meteoroids impacting the moon are identified. Most meteoroids producing small impact-seismic events, including ones associated with cometary showers, appear to approach from retrograde heliocentric orbits. In contrast, most meteoroids associated with large impact-seismic events appear to approach from prograde orbits; the observation is consistent with a hypothesis that many of them represent stony asteroidal material. It is suggested that the previously reported discrepancy between lunar and terrestrial meteoroid-flux estimates may be due to the differences in lunar and terrestrial detection efficiency among various families of meteoroids.

Oberst, Jurgen↗
NASA NTRS1988

Monthly mean global climatology of temperature, wind, geopotential height, and pressure for 0 - 120 km

A monthly mean climatology is presented of temperature, wind, and geopotential height with nearly pole-to-pole coverage (80 S to 80 N) for 0 to 210 km, which can be used as a function of altitude and pressure. The purpose is to provide a reference for various atmospheric research and analysis activities. Data sources and methods of computation are described; in general, hydrostatic and thermal wind balance are maintained at all levels and latitudes. As observed in a series of cross-sectional plots, this climatology accurately reproduces most of the characteristic features of the atmosphere such as equatorial wind and the general structure of the tropopause, stratopause, and mesopause. A series of zonal wind profiles is also represented comparing this climatological wind with monthly mean climatological direct wind measurements in the upper mesosphere and lower thermosphere. The temperature and zonal wind climatology at stratospheric levels is compared with corresponding data from the National Meteorological Center, and general agreement is observed between the two data sets. Tables of the climatological values as a function of latitude and height for each month are contained in Appendix B, and are also available in floppy disk.

Fleming, Eric L.↗
NASA NTRS1989

Global atmospheric moisture variability

Research efforts during FY-88 have focused on completion of several projects relating to analysis of FGGE data during SOP-1 and on expanded studies of global atmospheric moisture. In particular, a revised paper on the relationship between diabatic heating and baroclinicity in the South Pacific Convergence Zone (SPCZ) was submitted. A summary of completed studies on diagnostic convective parameterization was presented at the Satellite Meteorology and Oceanography Convergence last February. These investigations of diabatic heating in the SPCZ have demonstrated the requirement for a more quantitative description of atmospheric moisture. As a result, efforts were directed toward use of passive remote microwave measurements from the Nimbus-7 SMMR and the DOD's Special Sensor Microwave Imager (SSMI/I) as critical sources of moisture data. Activities this year are summarized.

Robertson, Franklin R.↗
NASA NTRS1991

Remote sensing of water vapor features

The three major objectives of the project are outlined: (1) to describe atmospheric water vapor features as functions of space and time; (2) to evaluate remotely sensed measurements of water vapor content; and (3) to study relations between fine-scale water vapor fields and convective activity. Data from several remote sensors were used. The studies used the GOES/VAS, HIS, and MAMS instruments have provided a progressively finer scale view of water vapor features.

Fuelberg, Henry E.↗
NASA NTRS1991

Radio interferometry

Geodetic and geophysical applications of radio interferometry are reviewed for the period 1987-1990. Emphasis is placed on geodetic very long baseline interferometry using Mark III and IIIA technology. Consideration is also given to observing campaigns and activities, data analysis techniques, and technique improvements.

Ray, Jim R.↗
NASA NTRS2017

Thermodynamics of iron-aluminum alloys at 1573 K

The activities of iron (Fe) and aluminum (Al) were measured in Fe-Al alloys at 1573 K using the ion-current-ratio technique in a high-temperature Knudsen cell mass spectrometer. The Fe-Al solutions exhibited negative deviations from ideality over the entire composition range. The activity coefficientsγ Fe, andγ A1 are given by the following equations as a function of mole fraction (x Fe,x Al): 0<χA1<0.4 ln(γ(Fe))=−4.511(±0.008)χ^(2)(A1) ln(γ(A1))=−4.462(±0.029)χ^(2)(Fe) +0.325(±0.013) 0.6<χ(A1)<1.0 ln(γ(Fe))=−4.065(±0.006)χ^(2)(A1)+0.099(±0.003) ln(γ(A1))=−4.092(±0.026)χ^(2)(Fe)+0.002(±0.001) The results showed good agreement with those obtained from previous investigations at other temperatures by extrapolation of the activity data to 1573 K.

Jacobson, Nathan S.↗
NASA NTRS1999

Java RMI Software Technology for the Payload Planning System of the International Space Station

The Payload Planning System is for experiment planning on the International Space Station. The planning process has a number of different aspects which need to be stored in a database which is then used to generate reports on the planning process in a variety of formats. This process is currently structured as a 3-tier client/server software architecture comprised of a Java applet at the front end, a Java server in the middle, and an Oracle database in the third tier. This system presently uses CGI, the Common Gateway Interface, to communicate between the user-interface and server tiers and Active Data Objects (ADO) to communicate between the server and database tiers. This project investigated other methods and tools for performing the communications between the three tiers of the current system so that both the system performance and software development time could be improved. We specifically found that for the hardware and software platforms that PPS is required to run on, the best solution is to use Java Remote Method Invocation (RMI) for communication between the client and server and SQLJ (Structured Query Language for Java) for server interaction with the database. Prototype implementations showed that RMI combined with SQLJ significantly improved performance and also greatly facilitated construction of the communication software.

Bryant, Barrett R.↗
NASA NTRS2004

SAE Mil-1394 For Military and Aerospace Vehicle Applications

Unique opportunity to utilize new technology while increasing vehicle and crew member safety. Demonstration of new technology that can be utilized for Crew Exploration Vehicle and other future manned vehicles. Future work for other cameras in the vehicle that can be IEEE1394 based without major vehicle modifications. Demonstrates that LM can share information and knowledge between internal groups and NASA to assist in providing a product in support of the NASA Return to Flight Activities. This upgrade will provide a flight active data bus that is 100 times faster than any similar bus on the vehicle.

Dunga, Larry↗
NASA NTRS2016

Health and Climate Impacts of Ocean-Going Vessels in East Asia

East Asia has the most rapidly growing shipping emissions of both CO2 and traditional air pollutants, but the least in-depth analysis. Full evaluation of all pollutants is needed to assess the impacts of shipping emissions. Here, using an advanced method based on detailed dynamic ship activity data, we show that shipping emissions in East Asia accounted for 16% of global shipping CO2 in 2013, compared to only 4-7% in 2002-2005. Increased emissions lead to large adverse health impacts, with 14,500-37,500 premature deaths per year. Global mean radiative forcing from East Asian shipping is initially negative, but would become positive after approximately eight years for constant current emissions. As a large fraction of vessels are registered elsewhere, joint efforts are necessary to reduce emissions and mitigate the climate and health impacts of shipping in the region.

climate change impacts↗
NASA NTRS2016

EVA Suit Microbial Leakage Investigation Project

The objective of this project is to collect microbial samples from various EVA suits to determine how much microbial contamination is typically released during simulated planetary exploration activities. Data will be released to the planetary protection and science communities, and advanced EVA system designers. In the best case scenario, we will discover that very little microbial contamination leaks from our current or prototype suit designs, in the worst case scenario, we will identify leak paths, learn more about what affects leakage--and we'll have a new, flight-certified swab tool for our EVA toolbox.

Falker, Jay↗
NASA NTRS2019

The Joint ESA/NASA Galileo/GPS Receiver Onboard the ISS – the GARISS Project

ESA and NASA conducted a joint Galileo/GPS space receiver experiment on-board the International Space Station (ISS). The objectives (Enderle 2017) of the joint project were to demonstrate the robustness of a combined Galileo/GPS waveform uploaded to NASA hardware already operating in the challenging space environment - the SCaN (Space Communications and Navigation) software defined radio (SDR) testbed (FPGA) - on-board the ISS. These activities data included the analysis of the Galileo/GPS signal and on-board Position/Velocity/Time (PVT) performance, processing of the Galileo/GPS raw data (code- and carrier phase) for Precise Orbit Determination (POD), and validate the added value of a space-borne dual GNSS receiver compared to a single-system GNSS receiver operating under the same conditions. This paper will provide a general overview of the Galileo/GPS experiment – called GARISS - on-board the ISS, describe design, test and validation and also the operations of the experiment. Further, the various analysis conducted in the con is joint project and also the results obtained will be presented with a focus on the (Precise) Orbit Determination results.

Enderle, Werner↗