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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1966

Dynamic Environment of the Ranger Spacecraft I Through IX (Final Report)

The dynamic environment of the Ranger spacecraft (I through IX)during the launch portion of flight is defined in this Report. Flight data from each of nine spacecraft launches have been reviewed and are included. The environments receiving emphasis herein include liftoff acoustics, liftoff and transonic vibration, and the transient vibrations of the various pyrotechnic and staging events in the launch sequence. The systems for data acquisition and analysis are briefly described. In addition, post-flight comparison of flight data and ground test specification levels is made, and the dynamic test program is briefly discussed.

SHOCK↗
NASA NTRS1972

Shuttle/Agena study. Volume 2, part 3: Preliminary test plans

Proposed testing for the Agena tug program is based upon best estimates of shuttle and Agena tug requirements and upon the Agena configuration currently envisioned to meet these requirements. The proposed tests are presented in development, qualification, system, and launch base test plans. These plans are based upon generalized requirements and assumed situations. The limitations of this study precluded all but minimal consideration of related shuttle orbiter and shuttle ground systems. The test plans include provisions for all testing from major component to systems level, identified as necessary to aid in confirmation of the modified Agena configuration for the space tug; considerations that crew safety requirements and new environmental conditions from shuttle interface effects do impose some new Agena testing requirements; considerations that many existing Agena flight-qualified components will be utilized and qualification testing will be minimal; testing not only for the Agena tug but also for new or modified items of handling or servicing equipment for supporting the Agena factory-to-launch sequence; and the assembly of required testing into a sequence-ordered series of events.

Source record↗
NASA NTRS1975

New evidence for impact origin of the Bushveld Complex, South Africa

The importance of hypervelocity impacts as a geologic process is demonstrated by the example of the Bushveld Complex and the (nearby) Vredefort Ring. Each is interpreted as the result of four simultaneous impacts modified by large-scale endogenic processes triggered by the impact event. The layered mafic sequence and the voluminous red granite associated with the complex are endogenic magmas, probably generated by pressure release accompanying crater excavation. Shock melting of older sedimentary rocks must have produced a layer of impact melt (the Rooiberg Felsite), the upper part of which was extruded over its originally chilled crust as a series of thick lava flows. Field evidence and radiometric age determinations indicate that the Bushveld Complex formed approximately 2000 billion years ago.

Rhodes, R. C.↗
NASA NTRS1980

Project Intelsat 5

With 12,000 voice circuits and 2 television channels, intelsat 5, the first of a new generation of international telecommunication satellites, has almost double the communication capability of early satellites in the series. The 1,928 kilogram (at a lunch) satellite will be placed into geosynchronous orbit over the Atlantic Ocean to provide communications between North America and Europe. The characteristics of the Atlas Centaur launch vehicle to be used are described and the flights events of the launch sequence are tabulated.

Source record↗
NASA NTRS1981

Mars - Paleostratigraphic restoration of buried surfaces in Tharsis montes

Volcanism in the Tharsis province of Mars occurred in several different areas and was generally continuous without large time intervals between eruptive episodes. Major lava flow units are numerous and extensive, but relatively thin. In many places, impact craters on buried surfaces project above younger flows that overlie them. A new application of crater dating methods has been developed to aid in the identification of these buried surfaces and to determine their lateral extent. The technique is especially adaptable to the Tharsis region where the stratigraphic succession of major flow units has been established by detailed geologic mapping. Knowledge of the overall stratigraphy allows correlations to be made between known and unknown surfaces by comparing their crater frequencies at diameters large enough to insure their recognition on the buried unit. The method has been applied to aid in the restoration of buried rock units and to construct a series of paleostratigraphic maps showing the sequence of major eruptive events in the Tharsis region.

Scott, D. H.↗
NASA NTRS1980

How many theories for the origin of /proto/life

The sequence of primordial chemical events leading to contemporary metabolism is considered, taking into account primordial reactants, amino acids, proteinoid, protocells, ATP, polynucleotides, and protein. The right kind of matter, thermal copolyamino acids, can organize itself into cell-like structures, in the absence of discrete lipid, when triggered to do so by water. Another unpredicted result of examination of the microsystems formed was the step-by-step realization that the component processes of a primitive form of replication were latent in the proteinoid microsystems. At the present time, four modes of primitive replication of proteinoid microsystems have been identified, plus one that has the appearance of protosexual reproduction. Two main conceptual pathways have received attention. One is the proteinoid theory, derived from experiments. The other is the DNA-first theory, for which attempts at conceptual construction and experimental support continue to be sought.

Fox, S. W.↗
NASA NTRS1984

Magnetorotational iron core collapse

During its final evolutionary stages, a massive star, as considered in current astrophysical theory, undergoes rapid collapse, thereby triggering a sequence of a catastrophic event which results in a Type II supernova explosion. A remnant neutron star or a black hole is left after the explosion. Stellar collapse occurs, when thermonuclear fusion has consumed the lighter elements present. At this stage, the core consists of iron. Difficulties arise regarding an appropriate model with respect to the core collapse. The present investigation is concerned with the evolution of a Type II supernova core including the effects of rotation and magnetic fields. A simple neutrino model is developed which reproduced the spherically symmetric results of Bowers and Wilson (1982). Several two-dimensional computational models of stellar collapse are studied, taking into account a case in which a 15 solar masses iron core was artificially given rotational and magnetic energy.

Symbalisty, E. M. D.↗
NASA NTRS1989

Origin of the DA and non-DA white dwarf stars

Various proposals for the bifurcation of the white dwarf cooling sequence are reviewed. 'Primordial' theories, in which the basic bifurcation of the white dwarf sequence is rooted in events predating the white dwarf stage of stellar evolution, are discussed, along with the competing 'mixing' theories in which processes occurring during the white dwarf stage are responsible for the existence of DA or non-DA stars. A new proposal is suggested, representing a two-channel scenario. In the DA channel, some process reduces the hydrogen layer mass to the value of less than 10 to the -7th. The non-DA channel is similar to that in the primordial scenario. These considerations suggest that some mechanism operates in both channels to reduce the thickness of the outermost layer of the white dwarf. It is also noted that accretion from the interstellar medium has little to do with whether a particular white dwarf becomes a DA or a non-DA star.

Shipman, Harry L.↗
NASA NTRS1992

Statistical mechanics of violent relaxation

We propose a functional that is extremized through violent relaxation. It is based on the Ansatz that the wave-particle scattering during violent dynamical processes can be approximated as a sequence of discrete scattering events that occur near a particle's perigalacticon. This functional has an extremum whose structure closely resembles that of spheroidal stellar systems such as elliptical galaxies. The results described here, therefore, provide a simple framework for understanding the physical nature of violent relaxation and support the view that galaxies are structured in accord with fundamental statistical principles.

Spergel, David N.↗
NASA NTRS1994

Reliability and life prediction of ceramic composite structures at elevated temperatures

Methods are highlighted that ascertain the structural reliability of components fabricated of composites with ceramic matrices reinforced with ceramic fibers or whiskers and subject to quasi-static load conditions at elevated temperatures. Each method focuses on a particular composite microstructure: whisker-toughened ceramics, laminated ceramic matrix composites, and fabric reinforced ceramic matrix composites. In addition, since elevated service temperatures usually involve time-dependent effects, a section dealing with reliability degradation as a function of load history has been included. A recurring theme throughout this chapter is that even though component failure is controlled by a sequence of many microfailure events, failure of ceramic composites will be modeled using macrovariables.

Duffy, Stephen F.↗
NASA NTRS2000

Onset of the Magnetic Explosion in Filament-Eruption Flares and CMEs

We present three-dimensional sketches of the magnetic field before and during filament eruptions in flares and coronal mass ejections. Before the eruption, the overall magnetic field is a closed bipole in which the core field (the field rooted along the bipole's neutral line in the photospheric magnetic flux) is strongly sheared and has oppositely curved "elbows" that bulge out from the opposite ends of the neutral line. This core-field sigmoid runs under and is pressed down in the middle by the rest of the field in the bipole, the less-sheared envelope field rooted outside the core field (as in the model of Antiochos, Dahlburg, & Klimchuk 1994, ApJ, 420, L4 1). A filament of chromospheric-temperature plasma is often held in the core field over the neutral line. In a filament eruption, the core field undergoes an explosive eruption, the frozen-in filament plasma providing a visible tracer of the erupting field. The core-field explosion may be either confined (as in some flares) or ejective (as in CMEs that begin together with the onset of a long-duration two-ribbon flare). We present examples of each of these two kind of events as observed in sequences of coronal X-ray images from the Yohkoh SXT, and consider (1) how the explosion begins, and (2) whether confined eruptions begin in basically the same way as ejective eruptions.

Moore, Ronald L.↗
NASA NTRS2000

Onset of the Magnetic Explosion in Filament-Eruption Flares and Coronal Mass Ejections: Single-Bipole Events

We present three-dimensional sketches of die magnetic field before and during filament eruptions in flares and coronal mass ejections. Before the eruption, the overall magnetic field is a closed bipole in which the core field (the field rooted along the bipole's neutral line in the photospheric magnetic flux) is strongly sheared and has oppositely curved "elbows" that bulge out from the opposite ends of the neutral line. This core-field sigmoid runs under and is pressed down in the middle by the rest of the field in the bipole, the less-sheared envelope field rooted outside the core field (as in the model of Antiochos, Dahlburg, & Klimchuk. A filament of chromospheric-temperature plasma is often held in the core field over the neutral line. In a filament eruption, the core field undergoes an explosive eruption, the frozen-in filament plasma providing a visible tracer of the erupting field. The core-field explosion may be either confined (as in some flares) or ejective (as in CMEs that begin together with the onset of a long-duration two-ribbon flare). We present examples of each of these two kind of events as observed in sequences of coronal X-ray images from the Yohkoh SXT, and consider (1) how the explosion begins, and (2) whether confined eruptions begin in basically the same way as ejective eruptions.

Moore, Ron L.↗
NASA NTRS2003

Furrow microtubules and localized exocytosis in cleaving Xenopus laevis embryos

In dividing Xenopus eggs, furrowing is accompanied by expansion of a new domain of plasma membrane in the cleavage plane. The source of the new membrane is known to include a store of oogenetically produced exocytotic vesicles, but the site where their exocytosis occurs has not been described. Previous work revealed a V-shaped array of microtubule bundles at the base of advancing furrows. Cold shock or exposure to nocodazole halted expansion of the new membrane domain, which suggests that these microtubules are involved in the localized exocytosis. In the present report, scanning electron microscopy revealed collections of pits or craters, up to approximately 1.5 micro m in diameter. These pits are evidently fusion pores at sites of recent exocytosis, clustered in the immediate vicinity of the deepening furrow base and therefore near the furrow microtubules. Confocal microscopy near the furrow base of live embryos labeled with the membrane dye FM1-43 captured time-lapse sequences of individual exocytotic events in which irregular patches of approximately 20 micro m(2) of unlabeled membrane abruptly displaced pre-existing FM1-43-labeled surface. In some cases, stable fusion pores, approximately 2 micro m in diameter, were seen at the surface for up to several minutes before suddenly delivering patches of unlabeled membrane. To test whether the presence of furrow microtubule bundles near the surface plays a role in directing or concentrating this localized exocytosis, membrane expansion was examined in embryos exposed to D(2)O to induce formation of microtubule monasters randomly under the surface. D(2)O treatment resulted in a rapid, uniform expansion of the egg surface via random, ectopic exocytosis of vesicles. This D(2)O-induced membrane expansion was completely blocked with nocodazole, indicating that the ectopic exocytosis was microtubule-dependent. Results indicate that exocytotic vesicles are present throughout the egg subcortex, and that the presence of microtubules near the surface is sufficient to mobilize them for exocytosis at the end of the cell cycle.

Non-NASA Center↗
NASA NTRS1998

Analysis of Tile-Reinforced Composite Armor: Advanced Modeling and Strength Analyses - Part 1

The results of an analytical and experimental study of the structural response and strength of tile-reinforced components of the Composite Armored Vehicle are presented. The analyses are based on specialized finite element techniques that properly account for the effects of the interaction between the armor tiles, the surrounding elastomers, and the glass-epoxy sublaminates. To validate the analytical predictions, tests were conducted with panels subjected to three-point bending loads. The sequence of progressive failure events for the laminates is described. This paper describes the results of Part 1 of a study of the response and strength of tile-reinforced composite armor.

Davila, C. G.↗
NASA NTRS2009

R4SA for Controlling Robots

The R4SA GUI mentioned in the immediately preceding article is a userfriendly interface for controlling one or more robot(s). This GUI makes it possible to perform meaningful real-time field experiments and research in robotics at an unmatched level of fidelity, within minutes of setup. It provides such powerful graphing modes as that of a digitizing oscilloscope that displays up to 250 variables at rates between 1 and 200 Hz. This GUI can be configured as multiple intuitive interfaces for acquisition of data, command, and control to enable rapid testing of subsystems or an entire robot system while simultaneously performing analysis of data. The R4SA software establishes an intuitive component-based design environment that can be easily reconfigured for any robotic platform by creating or editing setup configuration files. The R4SA GUI enables event-driven and conditional sequencing similar to those of Mars Exploration Rover (MER) operations. It has been certified as part of the MER ground support equipment and, therefore, is allowed to be utilized in conjunction with MER flight hardware. The R4SA GUI could also be adapted to use in embedded computing systems, other than that of the MER, for commanding and real-time analysis of data.

Aghazarian, Hrand↗
NASA NTRS2011

The 2010 May Flaring Episode of Cygnus X-3 in Radio, X-Rays, and gamma-Rays

In 2009, Cygnus X-3 (Cyg X-3) became the first microquasar to be detected in the GeV gamma-ray regime, via the satellites Fermi and AGILE. The addition of this new band to the observational toolbox holds promise for building a more detailed understanding of the relativistic jets of this and other systems. We present a rich dataset of radio, hard and soft X-ray, and gamma-ray observations of Cyg X-3 made during a flaring episode in 2010 May. We detect a approx.3-d softening and recovery of the X-ray emission, followed almost immediately by a approx.1-Jy radio flare at 15 GHz, followed by a 4.3sigma gamma-ray flare (E > 100 MeV) approx.1.5 d later. The radio sampling is sparse, but we use archival data to argue that it is unlikely the gamma-ray flare was followed by any significant unobserved radio flares. In this case, the sequencing of the observed events is difficult to explain in a model in which the gamma-ray emission is due to inverse Compton scattering of the companion star's radiation field. Our observations suggest that other mechanisms may also be responsible for gamma-ray emission from Cyg X-3.

Williams, Peter K. G.↗
NASA NTRS2015

Low Density Supersonic Decelerator Flight Dynamics Test-1 Flight Design and Targeting

NASA's Low Density Supersonic Decelerator (LDSD) program was established to identify, develop, and eventually qualify to Test [i.e. Technology] Readiness Level (TRL) - 6 aerodynamic decelerators for eventual use on Mars. Through comprehensive Mars application studies, two distinct Supersonic Inflatable Aerodynamic Decelerator (SIAD) designs were chosen that afforded the optimum balance of benefit, cost, and development risk. In addition, a Supersonic Disk Sail (SSDS) parachute design was chosen that satisfied the same criteria. The final phase of the multi-tiered qualification process involves Earth Supersonic Flight Dynamics Tests (SFDTs) within environmental conditions similar to those that would be experienced during a Mars Entry, Descent, and Landing (EDL) mission. The first of these flight tests (i.e. SFDT-1) was completed on June 28, 2014 with two more tests scheduled for the summer of 2015 and 2016, respectively. The basic flight design for all the SFDT flights is for the SFDT test vehicle to be ferried to a float altitude of 120 kilo-feet by a 34 thousand cubic feet (Mcf) heavy lift helium balloon. Once float altitude is reached, the test vehicle is released from the balloon, spun-up for stability, and accelerated to supersonic speeds using a Star48 solid rocket motor. After burnout of the Star48 motor the vehicle decelerates to pre-flight selected test conditions for the deployment of the SIAD system. After further deceleration with the SIAD deployed, the SSDS parachute is then deployed stressing the performance of the parachute in the wake of the SIAD augmented blunt body. The test vehicle/SIAD/parachute system then descends to splashdown in the Pacific Ocean for eventual recovery. This paper will discuss the development of both the test vehicle and the trajectory sequence including design trade-offs resulting from the interaction of both engineering efforts. In addition, the SFDT-1 nominal trajectory design and associated sensitivities will be discussed as well as an overview of the on-board flight software used to trigger and sequence the main flight events necessary to deploy the deceleration technologies. Finally, as-flown performance of the SFDT-1 system will be discussed.

Ivanov, Mark↗