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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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NASA NTRS2012

Effect of Population III Multiplicity on Dark Star Formation

We numerically study the mutual interaction between dark matter (DM) and Population III (Pop III) stellar systems in order to explore the possibility of Pop III dark stars within this physical scenario. We perform a cosmological simulation, initialized at z approx. 100, which follows the evolution of gas and DM. We analyze the formation of the first mini halo at z approx. 20 and the subsequent collapse of the gas to densities of 10(exp 12)/cu cm. We then use this simulation to initialize a set of smaller-scale 'cut-out' simulations in which we further refine the DM to have spatial resolution similar to that of the gas. We test multiple DM density profiles, and we employ the sink particle method to represent the accreting star-forming region. We find that, for a range of DM configurations, the motion of the Pop III star-disk system serves to separate the positions of the protostars with respect to the DM density peak, such that there is insufficient DM to influence the formation and evolution of the protostars for more than approx. 5000 years. In addition, the star-disk system causes gravitational scattering of the central DM to lower densities, further decreasing the influence of DM over time. Any DM-powered phase of Pop III stars will thus be very short-lived for the typical multiple system, and DM will not serve to significantly prolong the life of Pop III stars.

Stacy, Athena↗
NASA NTRS1990

Platform evolution studies

The polar orbiting platform (POP), being developed by the Work Package 3 (WP3) Project at the Goddard Space Flight Center, will play a key role in the NASA Leadership Initiative, Mission to Planet Earth (MPE). It becomes, with the addition of payloads, an Earth observation satellite observatory. Mission to Planet Earth also has geostationary platforms (GEOP) as part of its global observational system. A study was begun in March 1988 to assess the applicability of the POP orbital replacement units (ORUs) for a geostationary Earth observing mission. Two test cases, representative of MPE payloads, were studied. Case A was used to emphasize the GEOP configuration and design; it used a Titan/Centaur to achieve orbit. Case B, considered to be much further in the future, included some assembly at the Space Station Freedom manned base and use of an orbital transfer vehicle to achieve orbit; requirements on the manned base to support such a mission were emphasized. The study found the POP systems more than adequate to meet GEOP requirements. Two types of changes were required for the POP ORUs: (1) modification to use only one surface for heat rejection; for the battery ORU, this meant 'opening up' the ORU to retain the radiator area with a corresponding decrease in depth; and (2) deletion of equipment not needed. The Case A configuration was shown to be within the planned capability of the Titan IV/Centaur. Assembly requirements were included for the Case B configuration, which is driven by the large microwave antennas of two of the payloads. The final review was April 19, 1989.

Walton, Barbara A.↗
NASA NTRS1986

Approach trajectory planning system for maximum concealment

A computer-simulation study was undertaken to investigate a maximum concealment guidance technique (pop-up maneuver), which military aircraft may use to capture a glide path from masked, low-altitude flight typical of terrain following/terrain avoidance flight enroute. The guidance system applied to this problem is the Fuel Conservative Guidance System. Previous studies using this system have concentrated on the saving of fuel in basically conventional land and ship-based operations. Because this system is based on energy-management concepts, it also has direct application to the pop-up approach which exploits aircraft performance. Although the algorithm was initially designed to reduce fuel consumption, the commanded deceleration is at its upper limit during the pop-up and, therefore, is a good approximation of a minimum-time solution. Using the model of a powered-lift aircraft, the results of the study demonstrated that guidance commands generated by the system are well within the capability of an automatic flight-control system. Results for several initial approach conditions are presented.

Warner, David N., Jr.↗
NASA NTRS1989

The shocking development of lithium (and boron) in supernovae

It is shown that significant amounts of Li-7 and B-11 are produced in Type 2 supernovae. The synthesis of these rare elements occurs as the supernova shock traverses the base of the hydrogen envelope burning He-3 to masses 7 and 11 via alpha capture. The yields in this process are sufficient to account for the difference in lithium abundance observed between Pop 2 and Pop 1 stars. Since lithium (and boron) would, in this manner, be created in the same stars that produce the bulk of the heavy elements, the lithium abundance even in old Pop 1 stars would be high (as observed). The B-11 production may remedy the long-standing problem of the traditional spallation scenario to account for the observed isotopic ratio of boron. Observational consequences of this mechanism are discussed, including the evolution of lithium and boron isotope ratios in the Galaxy and the possible use of the boron yields to constrain the number of blue progenitor Type 2 supernovae.

Dearborn, David S. P.↗
NASA NTRS1989

The shocking development of lithium (and boron) in supernovae

It is shown that significant amounts of Li-7 and B-11 are produced in Type 2 supernovae. The synthesis of these rare elements occurs as the supernova shock traverses the base of the hydrogen envelope burning He-3 to masses 7 and 11 via alpha capture. The yields in this process are sufficient to account for the difference in lithium abundance observed between Pop 2 and Pop 1 stars. Since lithium (and boron) would, in this manner, be created in the same stars that produce the bulk of the heavy elements, the lithium abundance even in old Pop 1 stars would be high (as observed). The B-11 production may remedy the long-standing problem of the traditional spallation scenario to account for the observed isotopic ratio of boron. Observational consequences of this mechanism are discussed, including the evolution of lithium and boron isotope ratios in the Galaxy and the possible use of the boron yields to constrain the number of blue progenitor Type 2 supernovae.

Dearborn, David S. P.↗
NASA NTRS2008

Investigation of Flow Instabilities in the Inlet Ducts of DP-1C VTOL Aircraft

An investigation of flow instabilities in the inlet ducts of a two-engine vertical takeoff and landing aircraft DP-1C is described in this report. Recent tests revealed that the engines stall during run ups while the aircraft is operating on the ground. These pop stalls occurred at relatively low power levels, sometimes as low as 60 percent of the engine full speed. Inability to run the engines up to the full speed level is attributed to in-ground effects associated with hot gas ingestion. Such pop stalls were never experienced when the aircraft was tested on a elevated grid platform, which ensured that the aircraft was operating in out-of-the-ground-effect conditions. Based on available information on problems experienced with other vertical takeoff and landing aircraft designs, it was assumed that the engine stalls were caused by partial ingestion of hot gases streaming forward from the main exit nozzle under the aircraft inlets, which are very close to the ground. It was also suggested that the nose wheel undercarriage, located between the inlets, may generate vortices or an unstable wake causing intense mixing of hot exit gases with incoming inlet flow, which would enhance the hot gas ingestion. After running a short three-day series of tests with fully instrumented engine inlets, it is now believed the most probable reason for engine pop stalls are random ingestions of a vortex generated between the two streams moving in opposite directions: outbound hot gas stream from the main nozzle close to the ground and inbound inlet flow above. Originally, the vortex is in a horizontal plane. However, at a certain velocity ratio of these two streams, the vortex attaches either to the ground or the aircraft surface at one end and the other end is swallowed by one of the aircraft inlets. Once the vortex enters the inlet duct, a puff of hot air can be sucked through the vortex core into the engine, which causes a serious inlet flow field distortion followed by an engine stall. Once the engine stalls, the outflow from the inlet pushes the vortex away and the engine resumes normal operation. This hypothesis needs to be verified experimentally; e.g., by extensive smoke flow visualization ahead of the aircraft inlets.

Lepicovsky, Jan↗
NASA NTRS2012

Constraining the Statistics of Population III Binaries

We perform a cosmological simulation in order to model the growth and evolution of Population III (Pop III) stellar systems in a range of host minihalo environments. A Pop III multiple system forms in each of the ten minihaloes, and the overall mass function is top-heavy compared to the currently observed initial mass function in the Milky Way. Using a sink particle to represent each growing protostar, we examine the binary characteristics of the multiple systems, resolving orbits on scales as small as 20 AU. We find a binary fraction of approx. 36, with semi-major axes as large as 3000 AU. The distribution of orbital periods is slightly peaked at approx. < 900 yr, while the distribution of mass ratios is relatively flat. Of all sink particles formed within the ten minihaloes, approx. 50 are lost to mergers with larger sinks, and 50 of the remaining sinks are ejected from their star-forming disks. The large binary fraction may have important implications for Pop III evolution and nucleosynthesis, as well as the final fate of the first stars.

Statistics↗
NASA NTRS2017

Short-Term Forecasts Using NU-WRF for the Winter Olympics 2018

The NASA Unified-Weather Research and Forecasting model (NU-WRF) will be included for testing and evaluation in the forecast demonstration project (FDP) of the International Collaborative Experiment −PyeongChang 2018 Olympic and Paralympic (ICE-POP) Winter Games. An international array of radar and supporting ground based observations together with various forecast and now-cast models will be operational during ICE-POP. In conjunction with personnel from NASA's Goddard Space Flight Center, the NASA Short-term Prediction Research and Transition (SPoRT) Center is developing benchmark simulations for a real-time NU-WRF configuration to run during the FDP. ICE-POP observational datasets will be used to validate model simulations and investigate improved model physics and performance for prediction of snow events during the research phase (RDP) of the project The NU-WRF model simulations will also support NASA Global Precipitation Measurement (GPM) Mission ground-validation physical and direct validation activities in relation to verifying, testing and improving satellite-based snowfall retrieval algorithms over complex terrain.

forecasting↗
NASA NTRS1984

The X-ray emission of normal spiral galaxies

Some results of an Einstein Observatory survey of X-ray emitting spiral galaxies are reported. The sources were normally 10-100 times further away than M31. Luminosities of 10 to the 38th to 10 to the 40th erg/sec were calculated and could have been generated by Pop I and Pop II binary systems, supernova remnants and small nuclear sources. Highly positive correlations were found among properties such as the integrated X-ray, optical and radio emissions. The data will also be compared with similar data from star burst and elliptical galaxies.

Fabbiano, G.↗
NASA NTRS1985

Chondrules in the Qingzhen type-3 enstatite chondrite Possible precursor components and comparison to ordinary chondrite chondrules

The mineral composition of chondrules from a fragment of Qingzhen (EH3) fall was analyzed by neutron activation method. Unlike the ordinary chondrite (OC) chondrules (Gooding and Keil, 1981), the Qingzhen radial pyroxene (RP) and porphyritic pyroxene (PP) chondrules have similar bulk compositions. Porphyritic olivine-pyroxene (POP) chondrules are richer than PP and RP chondrules in refractory lithophiles and siderophiles. Elements in each of the following sets intercorrelate significantly: (1) Fe-Co-Ni-Ir-Au, probably derived from a metal component; (2) Ca-Eu-Se, which suggests an oldhamite-rich precursor; (3) Al-Sc-Hf, occurring in high concentrations in POP chondrules, this set suggesting the existence of a refractory lithophile-rich and olivine-rich component; (4) Na REE; and (5) Cl-Br. Sets (2) and (4) were not precursors of OC. The interelement ratios of refractory lithophiles such as Ca, Al, Ti, Sc, and REE are similar to CI ratios, suggesting that they originated in the earliest phases as silicates, which were sulfurized before chondrule formation.

Grossman, J. N.↗
NASA NTRS1988

Environments and populations of supernova remnants in the Large Magellanic Cloud

The stellar and interstellar environments of the 32 known SNRs in the LMC have been examined to determine the relative numbers of population I and II progenitors. At least 2/3 of the LMC SNRs are associated with pop I environments. The data suggest that the existing SNR surveys are biased against the detection of SNRs located in evolved star-forming regions, such as supershells produced by OB asociations, and in the cores of luminous H II regions. Therefore, the fraction of SNRs in pop I environments may be even higher. The results are compared to previous studies of SN statistics in late-type galaxies.

Chu, You-Hua↗
NASA NTRS1989

The Earth Observing System (EOS) SAR ground data system

NASA, in association with ESA and NASDA, will launch the Space Station Freedom in 1993. As a complement to the Space Station, several unmanned Polar-Orbit Platforms (POPs) will be developed, built and launched with suites of instruments devoted to remote-sensing for earth surface and atmosphere observations or to planetary and deep-space studies. Attention is presently given to the POPs-associated Earth Observing System SAR Ground Data System, which encompasses a SAR processor, a postprocessing subsystem, a geophysical processor, and a data management and control subsystem.

Curlander, John C.↗
NASA NTRS1991

Analysis of the potential application of the Davenport/Short information technology model to a research and development organization

Part of the role of the Mission Operations Lab is the development of budget inputs for Huntsville Operations/Payload Crew Training Center/Payload Operations Control Center (HOSC/PCTC/POCC) activity. These budget inputs are part of the formal Program Operating Plan (POP) process, which occurs twice yearly, and of the formal creation of the yearly operating plan. Both POPs and the operation plan serve the purpose of mapping out planned expenditures for the next fiscal year and for a number of outlying years. Based on these plans, the various Project Offices at the Center fund the HOSC/PCTC/POCC activity. Because of Mission Operations Lab's role in budget development, some of the Project Offices have begun looking to Mission Operations, and specifically the EO02 branch, to track expenditures and explain/justify any deviations from plans. EO02 has encountered difficulties acquiring the necessary information to perform this function. It appears that the necessary linkages with other units had not been fully developed and integrated with the flow of information in budget implementation. The purpose of this study is to document the budget process from the point of view of EO02 and to identify the steps necessary for it to effectively perform this role on a continuous basis.

Decker, Deron R.↗
NASA NTRS1996

Air Traffic Complexity Measurement Environment (ACME): Software User's Guide

A user's guide for the Air Traffic Complexity Measurement Environment (ACME) software is presented. The ACME consists of two major components, a complexity analysis tool and user interface. The Complexity Analysis Tool (CAT) analyzes complexity off-line, producing data files which may be examined interactively via the Complexity Data Analysis Tool (CDAT). The Complexity Analysis Tool is composed of three independently executing processes that communicate via PVM (Parallel Virtual Machine) and Unix sockets. The Runtime Data Management and Control process (RUNDMC) extracts flight plan and track information from a SAR input file, and sends the information to GARP (Generate Aircraft Routes Process) and CAT (Complexity Analysis Task). GARP in turn generates aircraft trajectories, which are utilized by CAT to calculate sector complexity. CAT writes flight plan, track and complexity data to an output file, which can be examined interactively. The Complexity Data Analysis Tool (CDAT) provides an interactive graphic environment for examining the complexity data produced by the Complexity Analysis Tool (CAT). CDAT can also play back track data extracted from System Analysis Recording (SAR) tapes. The CDAT user interface consists of a primary window, a controls window, and miscellaneous pop-ups. Aircraft track and position data is displayed in the main viewing area of the primary window. The controls window contains miscellaneous control and display items. Complexity data is displayed in pop-up windows. CDAT plays back sector complexity and aircraft track and position data as a function of time. Controls are provided to start and stop playback, adjust the playback rate, and reposition the display to a specified time.

Source record↗
NASA NTRS1999

Integrated Advanced Microwave Sounding Unit-A (AMSU-A). As-Designed Parts List: Electrical, Electronic and Electromechanical (EEE) As-Designed Parts List

This report comprises the Electrical, Electronic, and Electromechanical (EEE) As Designed Parts List to be used in the Integrated Advanced Microwave Sounding Unit-A (AMSU-A) instrument. The purpose of the EEE As-Designed Parts List is to provide a listing of EEE parts identified for use on the Integrated AMSU-A. All EEE parts used on the AMSU-A must meet the parts control requirements as defined in the Parts Control Plan (POP). All part applications are reviewed by the Parts Control Board (PCB) and granted approval if POP requirements are met. The "As Designed Parts Lists" indicates PCB approval status, and thus also serves as the Program Approved Parts List.

Lorenz, E.↗
NASA NTRS2004

The Vaguries of Pyroxene Nucleation and the Resulting Chondrule Textures

Pyroxene is a major phase in chondrules, but often follows olivine in the crystallization sequence and depending on the melting temperature and time may not nucleate readily upon cooling. Dynamic crystallization experiments based on total or near total melting were used to study PO (porphyritic olivine) and PP (Porphyritic pyroxene) compositions as defined by. The experiments showed that pyroxene nucleated only at subliquidus temperatures in the PP melts and rarely in the PO melts. Porphyritic chondrules with phenocrysts of both olivine and pyroxene (POP chondrules) were not easily produced in the experiments. POP chondrules are common and it is important for deciphering their formation that we understand pyroxene nucleation properties of chondrule melts.

Lofgren, G. E.↗
NASA NTRS2001

Aspect-Oriented Programming

Computer science has experienced an evolution in programming languages and systems from the crude assembly and machine codes of the earliest computers through concepts such as formula translation, procedural programming, structured programming, functional programming, logic programming, and programming with abstract data types. Each of these steps in programming technology has advanced our ability to achieve clear separation of concerns at the source code level. Currently, the dominant programming paradigm is object-oriented programming - the idea that one builds a software system by decomposing a problem into objects and then writing the code of those objects. Such objects abstract together behavior and data into a single conceptual and physical entity. Object-orientation is reflected in the entire spectrum of current software development methodologies and tools - we have OO methodologies, analysis and design tools, and OO programming languages. Writing complex applications such as graphical user interfaces, operating systems, and distributed applications while maintaining comprehensible source code has been made possible with OOP. Success at developing simpler systems leads to aspirations for greater complexity. Object orientation is a clever idea, but has certain limitations. We are now seeing that many requirements do not decompose neatly into behavior centered on a single locus. Object technology has difficulty localizing concerns invoking global constraints and pandemic behaviors, appropriately segregating concerns, and applying domain-specific knowledge. Post-object programming (POP) mechanisms that look to increase the expressiveness of the OO paradigm are a fertile arena for current research. Examples of POP technologies include domain-specific languages, generative programming, generic programming, constraint languages, reflection and metaprogramming, feature-oriented development, views/viewpoints, and asynchronous message brokering. (Czarneclu and Eisenecker s book includes a good survey of many of these technologies).

Elrad, Tzilla↗
NASA NTRS2004

Arrays of Bolometers for Far-infrared and Submillimeter Astronomy

We describe 12 x 32 arrays of semiconducting cryogenic bolometers designed for use in far-infrared and submillimeter cameras. These 12 x 32 arrays are constructed from 1 x 32 monolithic pop-up detectors developed at NASA Goddard Space Flight Center. The pop-up technology allows the construction of large arrays with high filling factors that provide efficient use of space in the focal planes of far-infrared and submillimeter astronomical instruments. This directly leads to a significant decrease in observing time. The prototype array is currently operating in SHARC II, a facility instrument in use at the Caltech Submillimeter Observatory (CSO). The elements of this array employ a bismuth absorber coating and quarter wave backshort to optimize the bolometer absorption for a passband centered at 350 microns. However, this resonant structure also provides good bolometer performance at 450 and 850 microns, the two additional SHARC II passbands. A second array is to be installed in the High-resolution Airborne Widebandwidth Camera (HAWC), a far-infrared imaging camera for the Stratospheric Observatory for Infrared Astronomy (SOFIA). This array is currently in the final stage of construction, and its completion is expected in early 2004. HAWC is scheduled for commissioning in 2005. The HAWC array employs titanium-gold absorbers and is optimized for uniform absorption from 40 to 300 microns to accommodate all four of its far-infrared passbands. We describe the details of the array construction including the mechanical design and electrical characterization of the constituent linear arrays, comparing the SHARC II and HAWC cases. We also summarize the overall characteristics of the final two-dimensional arrays. Finally, we show examples of array performance in the form of images obtained with SHARC II.

Chuss, D. T.↗