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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2010

DISCOVERY OF A 1.6 YEAR MAGNETIC ACTIVITY CYCLE IN THE EXOPLANET HOST STAR {iota} HOROLOGII

The Mount Wilson Ca HK survey revealed magnetic activity variations in a large sample of solar-type stars with timescales ranging from 2.5 to 25 years. This broad range of cycle periods is thought to reflect differences in the rotational properties and the depths of the surface convection zones for stars with various masses and ages. In 2007, we initiated a long-term monitoring campaign of Ca II H and K emission for a sample of 57 southern solar-type stars to measure their magnetic activity cycles and their rotational properties when possible. We report the discovery of a 1.6 year magnetic activity cycle in the exoplanet host star {iota} Horologii and obtain an estimate of the rotation period that is consistent with Hyades membership. This is the shortest activity cycle so far measured for a solar-type star and may be related to the short-timescale magnetic variations recently identified in the Sun and HD 49933 from helioseismic and asteroseismic measurements. Future asteroseismic observations of {iota} Hor can be compared to those obtained near the magnetic minimum in 2006 to search for cycle-induced shifts in the oscillation frequencies. If such short activity cycles are common in F stars, then NASA's Kepler mission should observe their effects in many of its long-term asteroseismic targets.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

ORNL Post-irradiation Examination (LAMDA) Final Report on Characterization of Irradiated Grade 92 Ferritic-Martensitic Steels

Irradiation effects on ferritic-martensitic steel Grade 92 were investigated in this project. Samples from two heats of Grade 92, i.e., G92-2b and NF616, were selected, which were irradiated in the High Flux Isotope Reactor (HFIR) and the Advanced Test Reactor (ATR), respectively. Samples from two heats of ferriticmartensitic steel T91, irradiated in the ATR, were also selected as references for the Grade 92 samples. The selected G92-2b samples were irradiated to 0.5–14.7 displacements per atom (dpa) at two temperature regimes: 400–497 °C and 683–720°C. The selection of the high irradiation temperatures up to ~720°C is to test the performance at such upper bound temperatures, which would provide insights for the upper bound applicable temperature for Grade 92. The selected NF616 and T91 samples were irradiated to 3–8.2 dpa at 292–448°C. Except for T91 heat2 samples in 3-mm diameter discs, all the other selected samples are of type SS-J2 miniature tensile specimens. Two Nuclear Science User Facilities (NSUF), i.e., the Irradiated Materials Examination and Testing (IMET) hot cell facility and the Low Activation Materials Design and Analysis (LAMDA) facility, were used in the Post-Irradiation Examination (PIE) activities for the selected samples, which include: Tensile tests at room temperature (IMET); Fractography of the tensile fracture surfaces (LAMDA: scanning electron microscopy and energy; dispersive spectroscopy); Vickers hardness measurements (LAMDA); and Microstructural characterization (LAMDA: electron backscatter diffraction, focused-ion beam, and transmission electron microscopy).

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS2010

Lunar and Meteorite Sample Education Disk Program - Space Rocks for Classrooms, Museums, Science Centers, and Libraries

NASA is eager for students and the public to experience lunar Apollo samples and meteorites first hand. Lunar rocks and soil, embedded in Lucite disks, are available for educators to use in their classrooms, museums, science centers, and public libraries for education activities and display. The sample education disks are valuable tools for engaging students in the exploration of the Solar System. Scientific research conducted on the Apollo rocks reveals the early history of our Earth-Moon system and meteorites reveal much of the history of the early solar system. The rocks help educators make the connections to this ancient history of our planet and solar system and the basic processes accretion, differentiation, impact and volcanism. With these samples, educators in museums, science centers, libraries, and classrooms can help students and the public understand the key questions pursued by many NASA planetary missions. The Office of the Curator at Johnson Space Center is in the process of reorganizing and renewing the Lunar and Meteorite Sample Education Disk Program to increase reach, security and accountability. The new program expands the reach of these exciting extraterrestrial rocks through increased access to training and educator borrowing. One of the expanded opportunities is that trained certified educators from science centers, museums, and libraries may now borrow the extraterrestrial rock samples. Previously the loan program was only open to classroom educators so the expansion will increase the public access to the samples and allow educators to make the critical connections to the exciting exploration missions taking place in our solar system. Each Lunar Disk contains three lunar rocks and three regolith soils embedded in Lucite. The anorthosite sample is a part of the magma ocean formed on the surface of Moon in the early melting period, the basalt is part of the extensive lunar mare lava flows, and the breccias sample is an important example of the violent impact history of the Moon. The disks also include two regolith soils and orange glass from a pyroclastic deposit. Each Meteorite Disk contains two ordinary chondrites, one carbonaceous chondrite, one iron, one stony iron, and one achondrite. These samples will help educators share the early history of the solar system with students and the public. Educators may borrow either lunar or meteorite disks and the accompanying education materials through the Johnson Space Center Curatorial Office. In trainings provided by the NASA Aerospace Education Services Program specialists, educators certified to borrow the disk learn about education resources, the proper use of the samples, and the special security for care and shipping of the disks. The Lunar and Meteorite Sample Education Disk Program will take NASA exploration to more people. Getting Space Rocks out to the public and inspiring the public about new space exploration is the focus of the NASA disk loan program.

Allen, Jaclyn↗
NASA NTRS2014

Integrated Attitude Control Strategy for the Asteroid Redirect Mission

A deep-space mission has been proposed to redirect an asteroid to a distant retrograde orbit around the moon using a robotic vehicle, the Asteroid Redirect Vehicle (ARV). In this orbit, astronauts will rendezvous with the ARV using the Orion spacecraft. The integrated attitude control concept that Orion will use for approach and docking and for mated operations will be described. Details of the ARV's attitude control system and its associated constraints for redirecting the asteroid to the distant retrograde orbit around the moon will be provided. Once Orion is docked to the ARV, an overall description of the mated stack attitude during all phases of the mission will be presented using a coordinate system that was developed for this mission. Next, the thermal and power constraints of both the ARV and Orion will be discussed as well as how they are used to define the optimal integrated stack attitude. Lastly, the lighting and communications constraints necessary for the crew's extravehicular activity planned to retrieve samples from the asteroid will be examined. Similarly, the joint attitude control strategy that employs both the Orion and the ARV attitude control assets prior, during, and after each extravehicular activity will also be thoroughly discussed.

Lopez, Pedro, Jr.↗
DOE OSTI2013

Preconcentrator with high volume chiller for high vapor pressure particle detection

Apparatus and method for collecting particles of both high and low vapor pressure target materials entrained in a large volume sample gas stream. Large volume active cooling provides a cold air supply which is mixed with the sample gas stream to reduce the vapor pressure of the particles. In embodiments, a chiller cools air from ambient conditions to 0-15.degree. C. with the volumetric flow rate of the cold air supply being at least equal to the volumetric flow rate of the sample gas stream. In further embodiments an adsorption media is heated in at least two stages, a first of which is below a threshold temperature at which decomposition products of the high vapor pressure particle are generated.

47 OTHER INSTRUMENTATION↗
DOE OSTI2014

Morphology-controlled synthesis of Ti{sup 3+} self-doped yolk–shell structure titanium oxide with superior photocatalytic activity under visible light

Ti{sup 3+} self-doped yolk–shell structure titanium oxide nanoparticle aggregates are fabricated through an environmental template-free route and the reduction reaction at low temperature subsequently. After the Ti{sup 3+} doping, the reduced TiO{sub 2} sample exhibits a wide visible-light absorption ranged from 400 nm to 800 nm. The intrinsic hollow core–shell microstructure can make multiple reflections of light within the chamber, and thus results in more efficient use of the light source compared with solid structure. Besides, the large surface area can render the sample with a high activity. Therefore, Ti{sup 3+} self-doped yolk–shell structure titanium oxide exhibits a superior photocatalytic activity under visible light. This strategy is simple, cheap and mass-productive, which may shed light on a new avenue for large scale production of self-doped yolk–shell structural nano functional materials for catalyst, sensors, energy storage and other new applications. - Graphical abstract: A facile generic strategy is employed to prepare Ti{sup 3+} self-doped yolk–shell structure titanium oxide nanoparticle aggregates with the superior photocatalytic activity under visible light. - Highlights: • Yolk–shell TiO{sub 2} mesospheres are synthesized by solvothermal alcoholysis. • Ti{sup 3+} self-doped yolk–shell structure titanium oxide is obtained at low temperature. • It exhibits a remarkable photocatalytic activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

THE NATURE OF EXTREMELY RED H - [4.5] > 4 GALAXIES REVEALED WITH SEDS AND CANDELS

We have analyzed a sample of 25 extremely red H - [4.5] > 4 galaxies, selected using 4.5 {mu}m data from the Spitzer SEDS survey and deep H-band data from the Hubble Space Telescope CANDELS survey, over {approx}180 arcmin{sup 2} of the UKIDSS Ultra-Deep Survey field. Our aim is to investigate the nature of this rare population of mid-infrared (mid-IR) sources that display such extreme near-to-mid-IR colors. Using up to 17-band photometry (U through 8.0 {mu}m), we have studied in detail their spectral energy distributions, including possible degeneracies in the photometric redshift/internal extinction (z{sub phot}-A{sub V} ) plane. Our sample appears to include sources of very different nature. Between 45% and 75% of them are dust-obscured, massive galaxies at 3 < z{sub phot} < 5. All of the 24 {mu}m detected sources in our sample are in this category. Two of these have S(24 {mu}m)>300 {mu}Jy, which at 3 < z{sub phot} < 5 suggests that they probably host a dust-obscured active galactic nucleus. Our sample also contains four highly obscured (A{sub V} > 5) sources at z{sub phot} < 1. Finally, we analyze in detail two z{sub phot} {approx} 6 galaxy candidates, and discuss their plausibility and implications. Overall, our red galaxy sample contains the tip of the iceberg of a larger population of z > 3 galaxies to be discovered with the future James Webb Space Telescope.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2012

The Cosmic History of Hot Gas Cooling and Radio AGN Activity in Massive Early-Type Galaxies

We study the X-ray properties of 393 optically selected early-type galaxies (ETGs) over the redshift range of z approx equals 0.0-1.2 in the Chandra Deep Fields. To measure the average X-ray properties of the ETG population, we use X-ray stacking analyses with a subset of 158 passive ETGs (148 of which were individually undetected in X-ray). This ETG subset was constructed to span the redshift ranges of z = 0.1-1.2 in the approx equals 4 Ms CDF-S and approx equals 2 Ms CDF-N and z = 0.1-0.6 in the approx equals 250 ks E-CDF-S where the contribution from individually undetected AGNs is expected to be negligible in our stacking. We find that 55 of the ETGs are detected individually in the X-rays, and 12 of these galaxies have properties consistent with being passive hot-gas dominated systems (i.e., systems not dominated by an X-ray bright Active Galactic Nucleus; AGN). On the basis of our analyses, we find little evolution in the mean 0.5-2 keY to B-band luminosity ratio (L(sub x) /L(sub Beta) varies as [1 +z]) since z approx equals 1.2, implying that some heating mechanism prevents the gas from cooling in these systems. We consider that feedback from radio-mode AGN activity could be responsible for heating the gas. We select radio AGNs in the ETG population using their far-infrared/radio flux ratio. Our radio observations allow us to constrain the duty cycle history of radio AGN activity in our ETG sample. We estimate that if scaling relations between radio and mechanical power hold out to z approx equals 1.2 for the ETG population being studied here, the average mechanical power from AGN activity is a factor of approx equals1.4 -- 2.6 times larger than the average radiative cooling power from hot gas over the redshift range z approx equals 0-1.2. The excess of inferred AGN mechanical power from these ETGs is consistent with that found in the local Universe for similar types of galaxies.

Danielson, A. L. R.↗
NASA NTRS1999

Prediction of ECS and SSC Models for Flux-Limited Samples of Gamma-Ray Blazars

The external Compton scattering (ECS) and synchrotron self-Compton (SSC) models make distinct predictions for the amount of Doppler boosting of high-energy gamma-rays emitted by Nazar. We examine how these differences affect the predicted properties of active galactic nucleus (AGN) samples selected on the basis of Murray emission. We create simulated flux-limited samples based on the ECS and SSC models, and compare their properties to those of identified EGRET blazars. We find that for small gamma-ray-selected samples, the two models make very similar predictions, and cannot be reliably distinguished. This is primarily due to the fact that not only the Doppler factor, but also the cosmological distance and intrinsic luminosity play a role in determining whether an AGN is included in a flux-limited gamma-ray sample.

Lister, Matthew L.↗
DOE OSTI2011

Exploration Of Activity Measurements And Equilibrium Checks For Sediment Dating Using Thick-Window Germanium Detectors

Activity measurements on sediment samples for trapped-charge geological dating using gamma-ray spectroscopy are an important verification of the field-site dose rate determination. Furthermore gamma-ray spectroscopy can check if the natural decay series are in secular equilibrium which is a crucial assumption in such dating. Typically the activities of leading members of the Thorium and Uranium decay series are measured, which requires Germanium detectors with thin windows and good energy resolution in order to effectively detect the associated low energy gamma-rays. Such equipment is not always readily available. The potential of conventional Germanium detectors with thick entrance window has been explored towards routine gamma-ray spectroscopy of sediment samples using higher energy gamma-rays. Alternative isotopes, such as Ac-228 and Pb-212 for the Thorium series, and Pa-234m, Ra-226 and Bi-214 for the Uranium series, have been measured in order to determine the mass-specific activity for the respective series and possibly provide a check of secular equilibrium. In addition to measurements of the K-40 activity, with the alternative approach, the activities of both decay series can be accurately determined. The secular equilibrium condition may be tested for the Thorium series. Measurement accuracy for Pa-234m is, however, not sufficient to permit also a reliable check of equilibrium for the Uranium series.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2018

Radiation History of Fission Gamma-Ray Spectra Relevant to Post-Detonation Debris Analysis

Quantifying the fissile content within trace amounts of nuclear material is of significant importance to safeguards and nuclear forensics communities. Traditionally, measurement methods have relied on destructive analysis (DA) measurements or passive detection of gamma/neutron signatures through nondestructive assay (NDA). These methods are highly accurate and employed globally as both a nuclear forensics capability and a material accountability measurement. However, common DA techniques rely on sample dissolution, a time-consuming process which can be particularly difficult for certain sample matrices, such as melt-glass formed from nuclear fallout. Likewise, trace quantities of nuclear materials prove difficult to measure using passive NDA techniques due to relatively low emission rates and potential interference from activated materials within the sample matrix.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1983

An H-alpha survey of southern hemisphere active chromosphere stars

Because of the variety of extraordinary phenomena exhibited by active chromosphere objects, discovery of new, bright surface-active stars is of considerable importance. Ca II emission is a well-known signature of chromospheric activity, serving even as one of the points of definition of the class of RS CVn binary stars. In connection with the present investigation, spectroscopic observations of 27 Ca II emission stars have been conducted. The observations make it possible to identify unambiguously the most chromospherically active stars in the sample. By observing the H-alpha line, rather than H and K, it is possible to distinguish nine of these stars which are likely to be observational targets as interesting as the extremely surface active objects V711 Tau or FK Com. Of the 27 stars surveyed, two (HD 86005, HD 204128) showed H-alpha as an emission feature above continuum, with estimated equivalent width 1-2 A.

Bopp, B. W.↗
NASA NTRS2000

A Review of New and Developing Technology to Significantly Improve Mars Sample-Return Missions

A JPL development activity was initiated in FY 1999 for the purpose of examining and evaluating technologies that could materially improve future (i.e., beyond the 2005 launch) Mars sample return missions. The scope of the technology review was comprehensive and end-to-end; the goal was to improve mass, cost, risk, and scientific return. A specific objective was to assess approaches to sample return with only one Earth launch. While the objective of the study was specifically for sample-return, in-situ missions can also benefit from using many of the technologies examined.

Carsey, F.↗
DOE OSTI2020

Engineering Active Fe Sites on Nickel–Iron Layered Double Hydroxide through Component Segregation for Oxygen Evolution Reaction

Nickel-iron layered double hydroxide (NiFe LDH) is a promising oxygen evolution reaction (OER) electrocatalyst under alkaline conditions. Much research has been performed to understand the structure-activity relationship of NiFe LDH under OER conditions. However, the specific role of the Fe species remains unclear and under debate. Herein, based on DFT calculations, it was discovered that the edge Fe sites show higher activity towards OER than either the edge Ni sites or lattice sites. Therefore, a facile acid-etching method was proposed to controllably induce the formation of edge Fe sites in NiFe LDH, and the obtained sample exhibited higher OER activity. X-ray absorption near edge structure and extended X-ray absorption fine structure analyses further revealed that the interaction of the edge Fe species with Ni is believed to contribute to the enhancement of the OER performance. This work provides a new understanding of the structure-activity relationship in NiFe LDH and offers a facile method for the design of efficient electrocatalysts in an alkaline environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Functional Principal Component Analysis of Radio–Optical Reference Frame Tie

The Gaia optical reference frame is intrinsically undefined with respect to global orientation and spin, so it needs to be anchored in the radio-based International Celestial Reference Frame (ICRF) to provide a referenced and quasi-inertial celestial coordinate system. The link between the two fundamental frames is realized through two samples of distant extragalactic sources, mostly active galactic nuclei and quasars, but only the smaller sample of radio-loud ICRF sources with optical counterparts is available to determine the mutual orientation. The robustness of this link can be mathematically formulated in the framework of functional principal component analysis using a set of vector spherical harmonics to represent the differences in celestial positions of the common objects. The weakest eigenvectors are computed, which describe the greatest deficiency of the link. The deficient or poorly determined terms are specific vector fields on the sphere that carry the largest errors of absolute astrometry using Gaia in reference to the ICRF. This analysis provides guidelines for the future development of the ICRF maximizing the accuracy of the link over the entire celestial sphere. A measure of the robustness of a least-squares solution, which can be applied to any linear model fitting problem, is introduced to help discriminate between reference frame tie models of different degrees.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1971

Meteoroid activity on the lunar surface from the Surveyor 3 sample examination

The Surveyor 3 television camera shroud and polished aluminum tube, retrieved as a result of the Apollo 12 mission after 2-1/2 years on the lunar surface, were examined at the NASA Manned Spacecraft Center for evidence of meteoroid impact. The results of this examination were compared with other estimates of the meteoroid flux in the lunar vicinity and are shown to be in good agreement with the Lunar Orbiter penetration rates. In addition, the relationship between a derived lunar surface meteoroid cumulative-flux model and the comparable near-earth model is discussed in the light of theoretical predictions. It is shown that the effect of the gravitational field of the earth on the near-earth environment was greater than previously predicted. The implication is that the average meteoroid velocity relative to the earth is probably 17 km/s. The many low velocity impacts on the Surveyor 3 camera and tube are shown to be of lunar surface origin and to be primarily the result of rocket exhaust interaction.

Cour-Palais, B. G.↗
NASA NTRS1972

Meteoroid activity on the lunar surface from the Surveyor 3 sample examination.

The Surveyor 3 television camera shroud and polished aluminum tube, retrieved as a result of the Apollo 12 mission after 2.5 years on the lunar surface, were examined for evidence of meteoroid impact. Resulting estimates of the meteoroid flux in the lunar vicinity are shown to be in good agreement with the Lunar Orbiter penetration rates. In addition, the relationship between a derived lunar-surface meteoroid cumulative-flux model and the comparable near-earth model is discussed in the light of theoretical predictions. It is shown that the effect of the gravitational field of the earth on the near-earth environment was greater than previously predicted.

Cour-Palais, B. G.↗
NASA NTRS2008

Extraction of Thermal Performance Values from Samples in the Lunar Dust Adhesion Bell Jar

A simulation chamber has been developed to test the performance of thermal control surfaces under dusty lunar conditions. The lunar dust adhesion bell jar (LDAB) is a diffusion pumped vacuum chamber (10(exp -8) Torr) built to test material samples less than about 7 cm in diameter. The LDAB has the following lunar dust simulant processing capabilities: heating and cooling while stirring in order to degas and remove adsorbed water; RF air-plasma for activating the dust and for organic contaminant removal; RF H/He-plasma to simulate solar wind; dust sieving system for controlling particle sizes; and a controlled means of introducing the activated dust to the samples under study. The LDAB is also fitted with an in situ Xe arc lamp solar simulator, and a cold box that can reach 30 K. Samples of thermal control surfaces (2.5 cm diameter) are introduced into the chamber for calorimetric evaluation using thermocouple instrumentation. The object of this paper is to present a thermal model of the samples under test conditions and to outline the procedure to extract the absorptance, emittance, and thermal efficiency from the pristine and sub-monolayer dust covered samples.

Gaier, James R.↗