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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 127 records · Page 7
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NASA NTRS2018

Statistical Analysis of Torus and Kink Instabilities in Solar Eruptions

A recent laboratory experiment of ideal magnetohydrodynamic instabilities revealed four distinct eruption regimes readily distinguished by the torus instability (TI) and helical kink instability (KI) parameters. To establish its observational counterpart, we collected 38 solar flares (stronger than GOES-class M5 in general) that took place within 45° of disk center during 2011–2017, 26 of which are associated with a halo or partial halo coronal mass ejection (CME; i.e., ejective events), while the others are CME-less (i.e., confined events). This is a complete sample of solar events satisfying our selection criteria detailed in the paper. For each event, we calculate a decay index n of the potential strapping field above the magnetic flux rope (MFR) in and around the flaring magnetic polarity inversion line (a TI parameter) and the unsigned twist number T(sub w) of the nonlinear force-free field lines forming the same MFR (a KI parameter). We then construct an n–T(sub w) diagram to investigate how the eruptiveness depends on these parameters. We find that (1) T(sub w) appears to play little role in discriminating between confined and ejective events; (2) the events with n ≳ 0.8 are all ejective, and all confined events have n ≲ 0.8. However, n ≳ 0.8 is not a necessary condition for eruption because some events with n ≲ 0.8 also erupted. In addition, we investigate the MFR’s geometrical parameters, apex height, and distance between footpoints, as a possible factors for the eruptiveness. We briefly discuss the difference of the present result for solar eruptions with that of the laboratory result in terms of the role played by magnetic reconnection.

Solar activity↗
NASA NTRS1992

NASA/DOD Aerospace Knowledge Diffusion Research Project. Report 11: Chronology of selected literature, reports, policy instruments, and significant events affecting Federal Scientific and Technical Information (STI) in the United States

The chronology is a comprehensive bibliography. It contains 512 entries covering a variety of selected literature, reports, policy instruments, and significant events affecting Federal Scientific and Technical Information (STI) from 1945 to 1990. It includes some publications and events of historic interest which relate to the evaluation of aerospace and aerospace knowledge diffusion. Each entry has been given an item number and items are arranged by columns. To provide an overview of Federal STI developments, the entries are generally arranged by date of publication and event.

Pinelli, Thomas E.↗
NASA NTRS1972

Irregular structure of thermal ion plasma near the plasmapause observed from Ogo 3 and Pc 1 measurements.

Independent measurements of the plasmapause and associated thermal plasma structure from Ogo 3 are compared with ground-based Pc 1 observations from the period 1966-67. Substantial agreement between the plasmapause crossing identified on the satellite and the Pc 1 occurrence positions observed on the ground at midlatitudes during the nighttime (including dawn and dusk) indicates that these nighttime Pc 1 events are closely associated with the plasmapause. A correlation of selected closely spaced events obtained in the nighttime under quiet to moderate activity provides good agreement in the proton concentrations near the plasmapause boundary. Preliminary results indicate Pc 1 excitation is associated with plasma irregularities near the plasmapause and is particularly favorable in the region of 'post-storm recovery' and in the region of diurnal 'plasma bulge' in the afternoon-dusk sector.

Kikuchi, H.↗
NASA NTRS1978

Summary of Voyager Design and Flight Loads

Estimates of flight loads for Voyager 1 and Voyager 2 are summarized and compared to the Voyager design loads obtained from the shock spectra/impedance method and to the loads obtained using space vehicle transient loads analysis. These estimates were obtained by using the measured flight accelerations at the launch vehicle/spacecraft interface as forcing functions for the Voyager mathematical model. Based on these data, an assessment of the shock spectra/impedance loads method used for Voyager is presented. The following conclusions were reached: (1) the shock spectra approach provided reasonable conservative design loads for Voyager, (2) care has to be executed to insure that all critical events are accounted for in constructing shock spectra envelopes, (3) the selection of critical events is not always obvious, especially for those flight events wherein the spacecraft dynamic characteristics are important, and (4) the success of the method is strongly dependent on the analysts' experience and judgement.

Chen, J. C.↗
NASA NTRS1984

Dependence of the spectrum of Pc 3-4 pulsations on the interplanetary magnetic field

Dependence of the power spectrum of Pc 3-4 magnetic pulsations observed at the ATS 6 geosynchronous satellite on the interplanetary magnetic field (IMF) has been studied. Pulsation events that were observed near noon and exhibited harmonic structure are chosen for analysis. Further selected are pulsation events with identical fundamental frequency to study dependence of the power of pulsations at different harmonic bands on the IMF. A weak negative correlation is observed between the IMF cone angle theta-XB and the power of pulsations in the frequency range 20-70 mHz. Also, a positive correlation between the intensity of the IMF B(IMF) and the power of pulsations at 50-70 mHz is found. This B(IMF) control is present at all ranges of the cone angle. A comparison is conducted of this observation with the frequency of bow shock associated upstream waves predicted from a model of wave generation by a cyclotron resonance of ions reflected at the bow shock. The predicted frequency depends on the IMF as B(IMF) (cos theta-XB)-squared. Although this relation gives a proportionality between the frequency and B(IMF) qualitatively consistent with the observation, it does not explain the most obvious IMF control of the spectrum of the pulsations.

Takahashi, K.↗
NASA NTRS2014

First Searches for Optical Counterparts to Gravitational-Wave Candidate Events

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.

gravitational waves↗
NASA NTRS1988

Laser Doppler velocimeter multiplexer interface for simultaneous measured events

An Laser Doppler Velocimeter multiplexer interface (20) includes an event pulse synchronizer (162), which synchronizes data pulses from events A, B and C. Clock control (164) is connected to receive timing information on the data pushes from the synchronizer (162). Displays (24, 26, 28) are connected to receive clock signals from the clock control (164) for indicating a data rate for each of the measured events A, B and C. Display (3) is connected to receive clock signals form the clock control (164) to indicate a coincidence rate between data pulses for any selected combination of the measured events A, B and C. A multiplexer (156) receives the data pulses from the events A, B and C and rate data from the clock control (164). Multiplexer (156) has output (180) for supplying the data pulses and rate data to a single input of a data processing system. A multiplexer control (158) is connected to supply control signals to the multiplexer (156) for selecting the event data pulses and the rate data for output from the multiplexer (156). Multiplexer control (158) receives start signals from the pulse synchronizer (162) and user selected inputs for desired outputs from the multiplexer (156).

Dean R Harrison↗
NASA NTRS1998

Studies of Solar Flare and Interplanetary Particle Acceleration and Coordination of Ground-Based Solar Observations in Support of US and International Space Missions

A primary focus has been to conduct studies of particular types of hard X-ray evolution in solar flares and their associations with high energy interplanetary protons observed near Earth. Previously, two large investigations were conducted that revealed strong associations between episodes of progressive spectral hardening seen in solar events and interplanetary proton events (Kiplinger, 1995). An algorithm was developed for predicting interplanetary protons that is more accurate than those currently in use when hard X-ray spectra are available. The basic research on a third study of the remaining independent subset of Hard X-ray Burst Spectrometer (HXRBS) events randomly not selected by the original studies was completed. This third study involves independent analyses of the data by two analysts. The results echo the success of the earlier studies. Of 405 flares analyzed, 12 events were predicted to have associated interplanetary protons at the Space Environment Service Center (SESC) level. Of these, five events appear to be directly associated with SESC proton events, six other events had lower level associated proton events, and there was only one false alarm with no protons. Another study by Garcia and Kiplinger (1995) established that progressively hardening hard X-ray flares associated with interplanetary proton events are intrinsically cooler and not extremely intense in soft X-rays unless a "contaminating" large impulsive flare accompanies the hardening flare.

Kiplinger, Alan L.↗
NASA NTRS1988

Occultation studies of the solar system

Occultations of stars by planets, satellites, planetary ring systems, asteroids, and comets provide valuable opportunities to probe the Solar System in ways otherwise impossible from the surface of the earth. For example, one can precisely measure the size and shape of objects which are much too small to be resolved directly, accurately map the structure and transparency of ring systems, and detect the faintest trace of an atmosphere. In this investigation, researchers identify upcoming occultations through wide-ranging computer searches, provide accurate predictions for the more important events, and observe selected occultations with our specially designed portable photometric equipment. During the past year, researchers produced accurate predictions for an occultation of AG+40 degrees 0783 by 324 Bamberga on 8 December 1987 and coordinated efforts to observe this event. The occultation was successfully observed at 13 sites including two manned by Lowell Observatory astronomers.

Millis, Robert L.↗
NASA NTRSDate not supplied

Assessing Sediment Inputs into the Shoshone River in Wyoming to Determine Areas for Protection and Restoration Practices

In 2016, a routine repair operation at the Willwood Dam released tons of built-up sediment into the Shoshone River, polluting the river and killing thousands of fish. This release greatly concerned the communities that rely on the river for farming, recreation, and tourism. In partnership with the Wyoming Department of Environmental Quality (WDEQ), Shoshone River Partners, and the United States Geological Survey (USGS) Wyoming-Montana Water Science Center, this multipart project illustrated the application of high-resolution satellite imagery and hydrological modeling techniques to identify major tributaries contributing to sediment influxes into the Shoshone River between the Buffalo Bill Dam and the Willwood Dam. The team used PlanetScope and Sentinel-2 Multi-Spectral Instrument (MSI) satellite images to assess changes in the surface reflectance of the river in response to precipitation events. To determine these storm events, the team selected dates of interest using Global Precipitation Measurement (GPM) Integrated Multi-Spectral Retrieval (IMERG) and gauge precipitation data from the Global Historical Climatology Network Daily (GHCNd). The continuation of this research further quantified sediment influx in the Shoshone River following snowfall and melt events using the Soil & Water Assessment Tool (SWAT). The precipitation analysis and sediment contribution maps helped the partner organizations prioritize their current decision making and best management practices to specific sites along the river. The results demonstrated the feasibility of using PlanetScope data for categorizing sediment in the Shoshone River.

Caroline Williams↗
NASA NTRS2018

Combining Sparsity DEM Inversions with Event Tracking for AIA Data

We introduce a modified version of the ASGARD code (Automated Selection and Grouping of events in A/A Regional Data). Originally written to detect and group brightenings ("events") in the AIA EUV channels, it now includes the sparsity DEM inversion method and instead detects emission measure enhancements in different temperature bins. Ultimately, the goal is to automatically determine heating and cooling rates in different coronal structures.

Bethge, Christian↗
NASA NTRS1980

Coherent substructure of turbulence near the stagnation zone of a bluff body

The evolution of freestream turbulence in crossflow about a circular cylinder was studied in order to identify the existence of a coherent substructure which is the outcome of the amplification of freesteam turbulence by the stretching mechanism in diverging flow about a bluff body. Visualization of the flow events revealed the selective stretching of cross-vortex tubes and the emergence of an organized turbulent flow pattern near the cylinder stagnation zone. Significant amplification of the total turbulent energy of the streamwise fluctuating velocity was consistently monitored. Realization of selective amplification at scales larger than the neutral scale of the stagnation flow was indicated by the variation of the discrete streamwise turbulent energy. A most amplified scale, characteristic of the energy containing eddies within the coherent substructure and commensurate with the boundary-layer thickness, was detected. Penetration of the amplified turbulence into the cylinder boundary layer led to the retardation of separation and to a concurrent decrease in the drag coefficient at subcritical cylinder-diameter Reynolds numbers.

Sadeh, W. Z.↗
NASA NTRS1979

NASA's participation in the AVE-SESAME '79 program

NASA's Marshall Space Flight Center participated with its AVE (Atmospheric Variability Experiment) in a large interagency mesoscale and severe storms experiment identified herein as AVE-SESAME '79 (Atmospheric Variability Experiment-Severe Environmental Storms and Mesoscale Experiment 1979). A primary objective of NASA was to support an effort to acquire carefully edited sets of rawinsonde data during selected severe weather events for use in correlative and diagnostic studies with satellite and radar data obtained at approximately the same times. Data were acquired during six individual 24-h experiments on both the regional and storm scales over a network in the central United States that utilized approximately 20 supplemental rawinsonde sites meshed among 23 standard National Weather Service sites. Included among the six experiments are data obtained between 1200 GMT on April 10 and 1200 GMT on April 11, encompassing the formation and development period for the tornado-producing systems that devastated Wichita Falls, Texas, and other sections of Oklahoma and Texas. The other dates for which data sets are available are April 19-20 and 25-26, May 9-10 and 20-21, and June 7-8, 1979.

Hill, K.↗
NASA NTRS1981

A measurement of the antiproton flux in the cosmic rays

A balloon-borne instrument has been used to detect cosmic-ray antiprotons. These are identified topologically by the appearance of annihilation prongs in a thick lead-plate spark chamber. The initial recording of the data is enriched in potential antimatter events by a selective trigger. After a small subtraction for background, 14 identified antiprotons yield a flux of 1.7 plus or minus 0.00005 antiproton/(sq m ster sec MeV) between 130 and 320 MeV at the top of the atmosphere. When combined with higher energy antiproton flux measurements, this result indicates that the antiprotons have a spectrum whose shape is the same as that of the protons, but with a magnitude reduced by a factor of 1/3000.

Buffington, A.↗
NASA NTRS1984

The structure and energetics of midlatitude disturbances accompanying cold-air outbreaks over East Asia

The evolution of extratropical transient waves as they propagate eastward from the Eurasian land mass toward the Pacific during selected cold surge events in the winter Monsoon Experiment (MONEX) is studied. The outstanding cold surge episodes during MONEX are first identified, and the salient synoptic features related to these events are described using composite streamline charts. The structure of rapidly varying disturbances accompanying the cold surges and the associated energetics are examined, and the behavior of those fluctuations over relatively longer time scales is addressed.

Lau, N.-C.↗
NASA NTRS1985

Gamma-radiation with E gamma 5 MeV detected from Seyfert galaxy 3C120 and region with 1" = 190 deg and b" = 20 deg

The observation of the Galaxy anticenter region in gamma-rays with E gamma = 5 / 100 MeV was made by gamma-telescope Natalya-1 in a balloon flight. The flight was performed at the ceiling 5.1 + or - 0.1 g/sq cm, magnetic cutoff being 17 GV. The description of the instrument and the analysis of the experiment conditions are given. The tracks of electron-positron pairs generated by gamma-quanta in the convertors were detected by wire spark chambers. The recorded events were classified manually by an operator using a graphic display into three classes: pairs, single and bad events. The arrival angle of gamma-quanta and their energy for selected gamma-ray events (pairs and singles) were determined through multiple scattering of pair components in the convertors. On the basis of the data obtained the celestial maps were made in gamma-rays for E sub gamma 5 MeV and E gamma 20 MeV energy ranges.

Damle, S. V.↗
NASA NTRS1985

Search for long-lived massive particles in extensive air showers

Air showers containing delayed sub-showers which may be produced by a long-lived massive particle have been investigated by using twelve detectors. Ten events have been selected out as the candidates. However, a definite conclusion cannot be reached at the present time.

Kawamoto, M.↗
NASA NTRS1991

Occultation studies of the solar system

Occultations of stars by planets, satellites, planetary ring systems, and asteroids offer opportunities to study the occulting bodies in ways not otherwise possible from the surface of the Earth. For example, one can detect even an extremely tenuous atmosphere and can measure the temperature and density profiles of the atmosphere in regions not ordinarily sampled by spacecraft. Occultations also permit direct measurement of the size and shape of solar system objects too small to be directly resolved by groundbased telescopes. The accuracy of such determinations is typically 1-2 percent and, moreover, is independent of the distance to the object. In this investigation, upcoming occultations through wide-ranging computer searches are identified, and accurate predictions for the more important events are provided. Selected occultations are observed with specially designed portable photometric equipment.

Millis, Robert L.↗