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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Episodic total ozone minima and associated effects on heterogeneous chemistry and lower stratospheric transport

Three-dimensional model simulations are used to describe the January 31, 1989 ozone minihole over Stavanger, Norway. This minihole is typical of many transient events in the lower stratosphere that arise because of cyclonic-scale disturbances in the troposphere. Although the ozone reduction is a short-lived reversible dynamical event, through heterogeneous chemical processes there can be a significant transfer of chlorine from reservoir molecules to active radicals. This chemically perturbed air is defined as processed air, and it is found that a single event can produce enough processed air to reduce the HCl in the entire polar vortex. Chemical processing on clouds associated with transient events is shown to be a major source of processed air in the polar vortex in December before background temperatures are cold enough for more uniform heterogeneous conversion.

Rood, Richard B.↗
NASA NTRS1992

The Target: H2O on the Moon

The importance of H2O on the lunar surface has long been identified as a high priority for the existence of a human colony for mining activities and, more recently, for space fuel. Using the Earth as an analog, volcanic activity would suggest the generation of water during lunar history. Evidence of volcanism is found not only in present lunar morphology, but in over 400 locations of lunar transient events cataloged by Middlehurst and Kuiper in the 1960's. These events consisted of sightings since early history of vapor emissions and bright spots or flares. Later infrared scanning by Saari and Shorthill showed 'hot spots', many of which coincided with transient event sites. Many of the locations of Middlehurst and Kuiper were the sites of repeat events, leading to the conclusion that these were possibly volcanic in nature. The detection and use of H2O from the lunar surface is discussed.

Green, J.↗
NASA NTRS1993

Extreme Ultraviolet Explorer observations of the magnetic cataclysmic variable RE 1938-461

The magnetic cataclysmic variable RE 1938-461 was observed by the Extreme Ultraviolet Explorer (EUVE) Deep Survey instrument on 1992 July 8-9 during in-orbit calibration. It was detected in the Lexan/ boron (65-190 A) band, with a quiescent count rate of 0.0062 +/- 0.0017/s, and was not detected in the aluminum/carbon (160-360 A) band. The Lexan/boron count rate is lower than the corresponding ROSAT wide-field camera Lexan/boron count rate. This is consistent with the fact that the source was in a low state during an optical observation performed just after the EUVE observation, whereas it was in an optical high state during the ROSAT observation. The quiescent count rates are consistent with a virtual cessation of accretion. Two transient events lasting about 1 hr occurred during the Lexan/boron pointing, the second at a count rate of 0.050 +/- 0.006/s. This appears to be the first detection of an EUV transient during the low state of a magnetic cataclysmic variable. We propose two possible explanations for the transient events.

Warren, John K.↗
NASA NTRS1975

Continuous observations of long-term variations in cosmic X-ray sources

Results are reported for the Charged Particle Measurements Experiment which was conducted on board IMP-7 to detect X-ray fluxes from the sun, the galactic center, Tau X-1, and Sco X-1 over a nine-month period. Autocorrelation analysis of the data indicates a probable 80-day periodicity in the flux from Sco X-1, a 110-day periodicity in the flux from the galactic center, no periodicities in the flux from Tau X-1, and a strong 27-day periodicity in the solar X-ray flux. A transient event detected within the cluster of sources constituting the galactic center is reported which lasted about two months and had a flux roughly equal to the regular flux from this area. It is noted that this was the only transient event detected in the whole area under continuous observation for the duration of the experiment.

Wende, C. D.↗
NASA NTRS1984

Type II bursts, shock waves, and coronal transients - The event of 1980 June 29, 0233 UT

The metric Type-II solar burst event of June 29, 1980, is characterized on the basis of spatially resolved radioheliograph observations obtained at Culgoora, Australia, and visible-light observations obtained with the coronograph/polarimeter of the SMM satellite. The data are presented in images, diagrams, and graphs and discussed in detail. The Type-II emission is found to arise in the dense moving material behind the transient loops, which have sky-plane width 0.5 solar radius and line-of-sight depth 0.1-0.4 solar radius. A faint arc observed moving ahead of the transient loops at about 900 km/sec and not associated with the Type-II burst is attributed to a shock front, and the compression ratio and Alfven Mach number of the enhanced-density region are estimated as n2/n1 = 1.3-3 and M(A) = 1.2-3. The ambient material at 3 solar radii is determined to have Alfven speed 250-625 km/sec and magnetic-field strength 50-120 mG. The total mass of the event is calculated as 700 Tg; the total magnetic energy of the loops is (1.5-15) x 10 to the 29th ergs.

Gary, D. E.↗
NASA NTRS2001

SWUIS-A: A Versatile, Low-Cost UV/VIS/IR Imaging System for Airborne Astronomy and Aeronomy Research

We have developed and successfully flight-tested on 14 different airborne missions the hardware and techniques for routinely conducting valuable astronomical and aeronomical observations from high-performance, two-seater military-type aircraft. The SWUIS-A (Southwest Universal Imaging System - Airborne) system consists of an image-intensified CCD camera with broad band response from the near-UV to the near IR, high-quality foreoptics, a miniaturized video recorder, an aircraft-to-camera power and telemetry interface with associated camera controls, and associated cables, filters, and other minor equipment. SWUIS-A's suite of high-quality foreoptics gives it selectable, variable focal length/variable field-of-view capabilities. The SWUIS-A camera frames at 60 Hz video rates, which is a key requirement for both jitter compensation and high time resolution (useful for occultation, lightning, and auroral studies). Broadband SWUIS-A image coadds can exceed a limiting magnitude of V = 10.5 in <1 sec with dark sky conditions. A valuable attribute of SWUIS-A airborne observations is the fact that the astronomer flies with the instrument, thereby providing Space Shuttle-like "payload specialist" capability to "close-the-loop" in real-time on the research done on each research mission. Key advantages of the small, high-performance aircraft on which we can fly SWUIS-A include significant cost savings over larger, more conventional airborne platforms, worldwide basing obviating the need for expensive, campaign-style movement of specialized large aircraft and their logistics support teams, and ultimately faster reaction times to transient events. Compared to ground-based instruments, airborne research platforms offer superior atmospheric transmission, the mobility to reach remote and often-times otherwise unreachable locations over the Earth, and virtually-guaranteed good weather for observing the sky. Compared to space-based instruments, airborne platforms typically offer substantial cost advantages and the freedom to fly along nearly any groundtrack route for transient event tracking such as occultations and eclipses.

Durda, Daniel D.↗
NASA NTRS2000

Development of Dynamic Flow Field Pressure Probes Suitable for Use in Large Scale Supersonic Wind Tunnels

A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10-by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor staff and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

Porro, A. Robert↗
NASA NTRS2001

Pressure Probe Designs for Dynamic Pressure Measurements in a Supersonic Flow Field

A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10- by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor stall and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

Porro, A. Robert↗
NASA NTRS2005

Sensor Webs: Autonomous Rapid Response to Monitor Transient Science Events

To better understand how physical phenomena, such as volcanic eruptions, evolve over time, multiple sensor observations over the duration of the event are required. Using sensor web approaches that integrate original detections by in-situ sensors and global-coverage, lower-resolution, on-orbit assets with automated rapid response observations from high resolution sensors, more observations of significant events can be made with increased temporal, spatial, and spectral resolution. This paper describes experiments using Earth Observing 1 (EO-1) along with other space and ground assets to implement progressive mission autonomy to identify, locate and image with high resolution instruments phenomena such as wildfires, volcanoes, floods and ice breakup. The software that plans, schedules and controls the various satellite assets are used to form ad hoc constellations which enable collaborative autonomous image collections triggered by transient phenomena. This software is both flight and ground based and works in concert to run all of the required assets cohesively and includes software that is model-based, artificial intelligence software.

Mandl, Dan↗
NASA NTRS2023

BatAnalysis - A Comprehensive Python Pipeline for Swift BAT Survey Analysis

The Swift Burst Alert Telescope (BAT) is a coded aperture gamma-ray instrument with a large field of view that primarily operates in survey mode when it is not triggering on transient events. The survey data consists of eighty-channel detector plane histograms that accumulate photon counts over time periods of at least 5 minutes. These histograms are processed on the ground and are used to produce the survey dataset between 14 and 195 keV. Survey data comprises >90% of all BAT data by volume and allows for the tracking of long term light curves and spectral properties of cataloged and uncataloged hard X-ray sources. Until now, the survey dataset has not been used to its full potential due to the complexity associated with its analysis and the lack of easily usable pipelines. Here, we introduce the BatAnalysis python package , a wrapper for HEASoftpy, which provides a modern, open-source pipeline to process and analyze BAT survey data. BatAnalysis allows members of the community to use BAT survey data in more advanced analyses of astrophysical sources including pulsars, pulsar wind nebula, active galactic nuclei, and other known/unknown transient events that may be detected in the hard X-ray band. We outline the steps taken by the python code and exemplify its usefulness and accuracy by analyzing survey data from the Crab Pulsar, NGC 2992, and a previously uncataloged MAXI Transient. The BatAnalysis package allows for ∼ 18 years of BAT survey to be used in a systematic way to study a large variety of astrophysical sources.

Tyler Parsotan↗
NASA NTRS2007

The Cusp: Open Questions

The northern and southern cusps play an important role in the overall solar wind-magnetosphere- ionosphere interaction. Optical, radar, and ground magnetometer observations of transient events in the dayside auroral oval provide strong evidence for bursty reconnection on the dayside magnetopause occurring along extended reconnection lines during periods of southward and/or ecliptic IMF orientation. During periods of northward IMF orientation, the same ground-based observations provide evidence for reconnection on the magnetopause poleward of the cusps. Cluster observations in the cusp have confirmed the transition in reconnection locations from the dayside to the high-latitude magnetopause as a function of IMF orientation, while in situ observations of the dayside magnetopause indicate that bursty reconnection frequently generates transient events marked by symmetric bipolar magnetic field signatures normal to the nominal magnetopause and magnetic field strength enhancements. In this talk we review recent and invoke new results from analytical, two-dimensional hybrid, and three-dimensional MHD codes to describe the motion and fate of the newly-reconnected magnetic field lines within FTEs, with a view to predicting (I) the locations where events form, (2) the mechanism(s) by which they are generated, (3) their signatures on the dayside and flank magnetopause, (4) their antisunward motion, (5) their interaction with the cusps, and (6) their signatures in the dayside auroral oval, including their occurrence patterns as a function of season. We compare these predictions with observations, in particular the results of a statistical study of Interball-1 FTEs and new multipoint THEMIS observations of FTEs.

Sibeck, D. G.↗
NASA NTRS2009

Radiation tolerant combinational logic cell

A system has a reduced sensitivity to Single Event Upset and/or Single Event Transient(s) compared to traditional logic devices. In a particular embodiment, the system includes an input, a logic block, a bias stage, a state machine, and an output. The logic block is coupled to the input. The logic block is for implementing a logic function, receiving a data set via the input, and generating a result f by applying the data set to the logic function. The bias stage is coupled to the logic block. The bias stage is for receiving the result from the logic block and presenting it to the state machine. The state machine is coupled to the bias stage. The state machine is for receiving, via the bias stage, the result generated by the logic block. The state machine is configured to retain a state value for the system. The state value is typically based on the result generated by the logic block. The output is coupled to the state machine. The output is for providing the value stored by the state machine. Some embodiments of the invention produce dual rail outputs Q and Q'. The logic block typically contains combinational logic and is similar, in size and transistor configuration, to a conventional CMOS combinational logic design. However, only a very small portion of the circuits of these embodiments, is sensitive to Single Event Upset and/or Single Event Transients.

Maki, Gary R.↗
NASA NTRS1985

A transient heating event in the history of a highlands troctolite from Apollo 12 soil 12033

A 2-mm particle, consisting of a troctolite clast attached to a small amount of glassy soil breccia, was found in a thin section of grains from Apollo 12 sample 12033,66. A description is given of the evolutionary history of the troctolite, taking into account the unique texture. It appears that the particle was broken from its parent rock and projected to Oceanus Procellarum from a source area in the highlands. Before, during, or after the flight, the troctolite was welded to a soil breccia by a minor amount of melting along the contact. It is argued that two separate heating events may be involved. The hypothesis is considered that the partial remelting and quenching of the troctolite took place very rapidly. Attention is given to melting experiments which test and confirm this hypothesis.

Marvin, U. B.↗
NASA NTRS1989

A transient auroral event on the dayside

A strong perturbation lasting about 10 min, beginning at 0930 UT on December 5, 1986, was recorded by high-latitude magnetometer stations in Greenland, Iqaluit, and the South Pole. Viking and Polar Bear satellite observations of the perturbation and observations of similar perturbations on the afternoon side in Svalbard, Heiss Island, and northern Siberia are also reported. It is suggested that the likely source of the perturbation is a magnetic disturbance in the solar wind observed by ISEE 1/2 and IMP 8. The perturbation is interpreted as an impulsive penetration of solar wind plasma on an interplanetary magnetic flux tube occurring through the magnetopause, ending in the low latitude boundary layer.

Heikkila, Walter J.↗