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All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Toward a lunar base

A research program leading to the development of a design for a permanent manned lunar base is described. Attention is given to the advantages offered by the lunar environment for materials processing and scientific investigations, due to the absence of an atmosphere and the plentiful supply of certain materials (iron and titanium). It is shown that once a controlled environment capsule is placed on the lunar surface, work could begin toward the construction of a permanent facility using lunar materials. It is pointed out that the research effort required for the design of a lunar base could perform concurrently with the R&D for the Space Station, resulting in the emplacement of a controlled environment capsule by the year 2007.

Duke, M. B.↗
NASA NTRS1988

Issues in management of artificial intelligence based projects

Now that Artificial Intelligence (AI) is gaining acceptance, it is important to examine some of the obstacles that still stand in the way of its progress. Ironically, many of these obstacles are related to management and are aggravated by the very characteristcs that make AI useful. The purpose of this paper is to heighten awareness of management issues in AI development and to focus attention on their resolution.

Kiss, P. A.↗
NASA NTRS2000

Evidence for Doppler-Shifted Iron Emission Lines in Black Hole Candidate 4U 1630-47

We report the first detection of a pair of correlated the X-ray spectrum of black hole candidate 4U 1630-47 outburst, based on Rossi X-Ray Timing Explorer (RXTE) emission lines in during its 1996 observations of the source. At the peak plateau of the outburst, the emission lines are detected, centered mostly at approx. 5.7 and approx. 7.7 keV, respectively, while the line energies exhibit random variability approx. 5%. Interestingly, the lines move in a concerted manner to keep their separation roughly constant. The lines also vary greatly in strength, but with the lower energy line always much stronger than the higher energy one. The measured equivalent width ranges from approx. 50 to approx. 270 eV for the former, and from insignificant detection to approx. 140 eV for the latter; the two are reasonably correlated. The correlation between the lines implies a causal connection; perhaps they share a common origin. Both lines may arise from a single K & alpha; line of highly ionized iron that is Doppler shifted either in a Keplerian accretion disk or in a bipolar outflow or even both. In both scenarios, a change in the line energy might simply reflect a change in the ionization state of line-emitting matter. We discuss the implication of the results and also raise some questions about such interpretations.

Cui, Wei↗
NASA NTRS1981

The sub-iron to iron ratios and the cosmic ray pathlength distribution

Data on the ratios of nuclei in the 21-25 charge range to iron, from the Danish-French cosmic ray isotope experiment on HEAO 3, are compared with cosmic ray propagation calculations based upon the latest cross sections. The results are incompatible with models in which the path length distribution has a peak at a path length larger than 1 g/sq cm, e.g., those in which there is more than 1 g/sq cm of matter around the cosmic ray source. They are most consistent with models in which the path length distribution includes substantial probabilities of having traversed very little matter.

Ormes, J. F.↗
NASA NTRS1989

Improving the low temperature ductility of NiAl

As part of a study aimed at developing a ductile NiAl-based alloy, ingots of Ni-Fe-Al alloys were cast and hot extruded to rods. The purpose of the iron additions was two-fold viz; to produce a change in the slip vector from 001 to 111 line and, in one alloy, to add a L1(2)-structured ductile second phase. Extruded Ni-20Al-30Fe was two-phase, containing a pro-eutectic B2 phase in a fine lamellar structure of B2+L1(2) phases. Room temperature tensile testing of both single extruded and double extruded alloys resulted in 8-percent and 22-percent plastic elongation and yield stresses of 850 and 760 MPa, respectively. Fracture in both cases occurred by ductile tearing of the eutectic and transgranular cleavage of the proeutectic phase at 1350 MPa. The ductility in double extruded condition is higher than that reported earlier in rapidly solidified wires by Inoue et al. (1984). By comparison, extruded single-phase B2-structured Ni-30Al-20Fe exhibited a fracture strength of 780 MPa, no plasticity, and a mixture of intergranular fracture and transgranular cleavage. This is contrast to earlier work by Inoue et al. where a yield stress of 400 MPa, 5 percent plastic strain, and a mixture of dimple and intergranular fracture was reported.

Guha, Sumit↗
NASA NTRS2004

Narrow Scale Flow and a Weak Field by the Top of Earth's Core: Evidence from Orsted, Magsat and Secular Variation

As Earth's main magnetic field weakens, our magnetic shield against the onslaught of the solar wind thins. And the field strength needed to fend off battering by solar coronal mass ejections is decreasing, just when the delicate complexity of modem, vulnerable, electro-technological systems is increasing at an unprecedented rate. Recently, a working group of distinguished scientist from across the nation has asked NASA's Solid Earth and Natural Hazards program a key question: What are the dynamics of Earth s magnetic field and its interactions with the Earth system? Paleomagnetic studies of crustal rocks magnetized in the geologic past reveal that polarity reversals have occurred many times during Earth s history. Networked super-computer simulations of core field and flow, including effects of gravitational, pressure, rotational Coriolis, magnetic and viscous forces, suggest how this might happen in detail. And space-based measurements of the real, time-varying magnetic field help constrain estimates of the speed and direction of fluid iron flowing near the top of the core and enable tests of some hypotheses about such flow. Now scientists at NASA s Goddard Space Flight Center have developed and applied methods to test the hypotheses of narrow scale flow and of a dynamically weak magnetic field near the top of Earth s core. Using two completely different methods, C. V. Voorhies has shown these hypotheses lead to specific theoretical forms for the "spectrum" of Earth s main magnetic field and the spectrum of its rate of change. Much as solar physicists use a prism to separate sunlight into its spectrum, from long wavelength red to short wavelength blue light, geophysicists use a digital prism, spherical harmonic analysis, to separate the measured geomagnetic field into its spectrum, from long to short wavelength fields. They do this for the rate of change of the field as well.

Voorhies, Coerte V.↗
NASA NTRS1999

Syntrophus aciditrophicus sp. nov., a new anaerobic bacterium that degrades fatty acids and benzoate in syntrophic association with hydrogen-using microorganisms

Strain SBT is a new, strictly anaerobic, gram-negative, nonmotile, non-sporeforming, rod-shaped bacterium that degrades benzoate and certain fatty acids in syntrophic association with hydrogen/formate-using microorganisms. Strain SBT produced approximately 3 mol of acetate and 0.6 mol of methane per mol of benzoate in coculture with Methanospirillum hungatei strain JF1. Saturated fatty acids, some unsaturated fatty acids, and methyl esters of butyrate and hexanoate also supported growth of strain SBT in coculture with Desulfovibrio strain G11. Strain SBT grew in pure culture with crotonate, producing acetate, butyrate, caproate, and hydrogen. The molar growth yield was 17 +/- 1 g cell dry mass per mol of crotonate. Strain SBT did not grow with fumarate, iron(III), polysulfide, or oxyanions of sulfur or nitrogen as electron acceptors with benzoate as the electron donor. The DNA base composition of strain SBT was 43.1 mol% G+C. Analysis of the 16 S rRNA gene sequence placed strain SBT in the delta-subdivision of the Proteobacteria, with sulfate-reducing bacteria. Strain SBT was most closely related to members of the genus Syntrophus. The clear phenotypic and genotypic differences between strain SBT and the two described species in the genus Syntrophus justify the formation of a new species, Syntrophus aciditrophicus.

Non-NASA Center↗
NASA NTRSDate not supplied

NASA GeneLab Platform Utilized for Biological Response to Space Radiation in Animal Models

Ionizing radiation from Galactic Cosmic Rays (GCR) is one of the major risk factors that will impact the health of astronauts on extended missions outside the protective effects of Earth’s magnetic field. The NASA GeneLab project has detailed information on radiation exposure using animal models with curated dosimetry information for spaceflight experiments. We analyzed multiple GeneLab omics datasets associated with both ground-based and spaceflight radiation studies that included in vivo and in vitro approaches. A range of ions from protons to iron particles with doses from 0.1 Gy to 1.0 Gy for ground studies and samples flown in Low Earth Orbit (LEO) with total doses of 1.0 mGy to 30 mGy were utilized From this analysis we were able to identify distinct biological signatures associating specific ions with specific biological responses due to radiation exposure in space. For example, we discovered changes in mitochondrial function, ribosomal assembly, and immune pathways as a function of dose. We provided a summary of how the GeneLab’s rich database of omics experiments with animal models can be used to generate novel hypotheses to better understand human health risks from GCR exposures.

Afshin Beheshti↗
NASA NTRSDate not supplied

NASA GeneLab Platform Utilized for Space Radiation Dosimetry Biological Response Compared to Radiation Ground Studies

Ionizing radiation from Galactic Cosmic Rays (GCR) is one of the major risk factors that will impact the health of astronauts on extended missions outside the protective effects of Earth’s magnetic field. The NASA GeneLab project has detailed information on radiation exposure using animal models with curated dosimetry information for spaceflight experiments. We analyzed multiple GeneLab omics datasets associated with both ground-based and spaceflight radiation studies that included in vivo and in vitro approaches. A range of ions from protons to iron particles with doses from 0.1 Gy to 1.0 Gy for ground studies and samples flown in Low Earth Orbit (LEO) with total doses of 1.0 mGy to 30 mGy were utilized From this analysis we were able to identify distinct biological signatures associating specific ions with specific biological responses due to radiation exposure in space. For example, we discovered changes in mitochondrial function, ribosomal assembly, and immune pathways as a function of dose. We provided a summary of how the GeneLab’s rich database of omics experiments with animal models can be used to generate novel hypotheses to better understand human health risks from GCR exposures.

Afshin Beheshti↗
NASA NTRS1988

Observation of Fe II (26.0 microns) in SN 1987A

The first observation of the 26-micron line from singly ionized iron in SN 1987A is reported. The total flux is 4.5 + or - 0.9 x 20 to the -18th W/sq cm. The line width (FWHM) is 4000 + or - 600 km/s. The minimum iron mass is found to be about 0.02 solar, indicating that the emission originates in the heavy element mantle and not in the hydrogen-rich envelope. Since this mass is less than estimates based on near-infrared measurements or the optical light curve, the emission is probably optically thick. In this case, the flux measurement together with the observed line width suggest a temperature of 3500 + or - 1500 K for the mantle. The broad line width suggests that mixing of the ejected iron with lighter elements in overlying layers has occurred.

Erickson, Edwin F.↗
NASA NTRS2015

Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

Dust↗
NASA NTRS2011

Iron Abundance in the Prototype PG 1159 Star, GW Vir Pulsator PG 1159-035, and Related Objects

We performed an iron abundance determination of the hot, hydrogen deficient post-AGB star PG 1159-035. which is the prototype of the PG 1159 spectral class and the GW Vir pulsators, and of two related objects (PG 1520+525, PG 1144+005), based on the first detection of Fe VIII lines in stellar photospheres. In another PG 1159 star. PG 1424+535. we detect Fe VII lines. In all four stars, each within T(sub eff) = 110,000-150,000 K, we find a solar iron abundance. This result agrees with our recent abundance analysis of the hottest PG 1159 stars (T(sub eff) = 150,000-200,000 K) that exhibit Fe x lines. On the whole, we find that the PG 1159 stars are not significantly iron deficient, in contrast to previous notions.

Werner, K.↗
NASA NTRS1977

Impact-induced energy partitioning, melting, and vaporization on terrestrial planets

The reported investigation was conducted in connection with the desirability to obtain information regarding the response of a solidified planetary surface to the primary impact of a meteoroid whose dimensions are small compared to that of the planet. The investigation is an extension of studies conducted by Ahrens and O'Keefe (1977) concerned with a calculation via finite-difference techniques of the entire flow field, the energy partitioning, and the quantity of melt and vapor produced upon impact of an iron object on a gabbroic anorthosite half-space at 15 km/sec. The assumptions used in these calculations are summarized. Calculations based on an equation of state for the low- and high-pressure mineral assemblage of gabbroic anorthosite, initial density 2.94 g/cu cm are considered. An algorithm is formulated for the description of the phase transformation upon shock loading. It is shown that the relative volume of melt and the equivalent volume of shock-induced vapor is proportional to the meteoroid kinetic energy (at high speeds) using the similarity scaling of projectile and target properties as suggested by Dienes and Walsh (1970).

Okeefe, J. D.↗
NASA NTRS2009

Suzaku View of the Swift/BAT Active Galactic Nuclei (I): Spectral Analysis of Six AGNs and Evidence for Two Types of Obscured Population

We present a systematic spectral analysis with Suzaku of six AGNs detected in the Swift/BAT hard X-ray (15-200 keV) survey, Swift J0138.6-4001, J0255.2-0011, J0350.1-5019, J0505.7-2348, J0601.9-8636, and J1628.1-5145. This is considered to be a representative sample of new AGNs without X-ray spectral information before the BAT survey. We find that the 0.5-200 keV spectra of these sources can be uniformly fit with a base model consisting of heavily absorbed (log NH >23.5/sq cm) transmitted components, scattered lights, a reflection component, and an iron-K emission line. There are two distinct groups, three "new type" AGNs (including the two sources reported by Ueda et al. 2007) with an extremely small scattered fraction (f(sub scat) < 0:5%) and strong reflection component (R = omega/2pi > or equal to 0.8 where omega is the solid angle of the reflector), and three "classical type" ones with f(sub scat > 0.5% and R < or approx. 0.8. The spectral parameters suggest that the new type has an optically thick torus for Thomson scattering (N(sub H) approx. 10(exp 25)/sq cm) with a small opening angle theta approx. 20deg viewed in a rather face-on geometry, while the classical type has a thin torus (N(sub H) approx. 10(exp 23-24)/sq cm) with theta > or approx. 30deg. We infer that a significant number of new type AGNs with an edge-on view is missing in the current all-sky hard X-ray surveys. Subject headings: galaxies: active . gamma rays: observations . X-rays: galaxies . X-rays: general

Eguchi, Satoshi↗
NASA NTRS2020

CALET on the International Space Station: the first three years of observations

The CALorimetric Electron Telescope CALET is a space instrument designed to carry out precision measurements of high energy cosmic-rays on the JEM-EF external platform on the International Space Station, where it has been collecting science data continuously since mid-October 2015. In addition to its primary goal of identifying nearby sources of high-energy electrons and possible signatures of dark matter in the electron spectrum, CALET is carrying out extensive measurements of the energy spectra, relative abundances and secondary-to-primary ratios of elements from proton to iron, and even above (up to Z = 40), studying the details of galactic particle propagation and acceleration. An overview of CALET based on the data taken during the first three years of observations is presented, including a direct measurement of the electron+positron energy spectrum from 11 GeV to 4.8 TeV. The proton spectrum has been measured from 50 GeV to 10 TeV covering, for the first time with a single space-borne instrument, the whole energy interval previously investigated in separate sub-ranges by magnetic spectrometers and calorimetric instruments. Preliminary spectra of cosmic-ray nuclei are also presented, together with gamma-ray observations and searches for an e.m. counterpart of LIGO/ Virgo GW events.

P Brogi↗
NASA NTRS1994

The metallicity of M4: Accurate spectroscopic fundamental parameters for four giants

High-quality spectra, covering the wavelength range 5480 to 7080 A, have been obtained for four giant stars in the intermediate-metallicity CN-bimodal globular cluster M4 (NGC 6121). We have employed a model atmosphere analysis that is entirely independent from cluster parameters, such as distance, age, and reddening, in order to derive accurate values for the stellar parameters effective temperature, surface gravity, and microturbulence, and for the abundance of iron relative to the Sun, (Fe/H), and of calcium, Ca/H, for each of the four stars. Detailed radiative transfer and statistical equilibrium calculations carried out for iron and calcium suggest that departures from local thermodynamic equilibrium are not significant for the purposes of our analysis. The spectroscopically derived effective temperatures for our program stars are hotter by about 200 K than existing photometric calibrations suggest. We conclude that this is due partly to the uncertain reddening of M4 and to the existing photometric temperature calibration for red giants being too cool by about 100 K. Comparison of our spectroscopic and existing photometric temperatures supports the prognosis of a significant east-west gradient in the reddening across M4. Our derived iron abundances are slightly higher than previous high-resolution studies suggested; the differences are most probably due to the different temperature scale and choice of microturbulent velocities adopted by earlier workers. The resulting value for the metallicity of M4 is (Fe/H )(sub M4) = -1.05 + or - 0.15. Based on this result, we suggest that metallicities derived in previous high-dispersion globular cluster abundance analyses could be too low by 0.2 to 0.3 dex. Our calcium abundances suggest an enhancement of calcium, an alpha element, over iron, relative to the Sun, in M4 of (Ca/H) = 0.23.

Drake, J. J.↗
NASA NTRS1975

Microwave resonance thermomagnetic analysis - A new method for characterizing fine-grained ferromagnetic constituents in lunar materials

Microwave resonance thermomagnetic analysis (MRTA) is the name given to a newly evolved technique for inferring the natures of fine-grained ferromagnetic constituents in lunar materials. Based on standard ferromagnetic resonance (FMR) procedures, the method makes use of the microwave skin effect for diagnosing the presence of metallic iron. Modelling experiments carried out on well-characterized iron and magnetitelike precipitates produced independently in simulated lunar glasses, coupled with published data for magnetite, provide a potential basis for detecting and discriminating between iron metal and ferric iron spinel, even when both are present in an unknown sample. Application of the technique to the lunar samples indicates the possible existence of magnetitelike phases in amounts up to about 0.3 wt% in soils from seven samples regions of the moon. These findings do not require any special geologic processes for their explanation, although some evidence supports the suggestion that fumarolic activity may have occurred in the lunar highlands.

Griscom, D. L.↗
NASA NTRS1976

Impact craters on Venus

Calculations are made to determine the sizes of stony and iron meteoroids which could penetrate the atmosphere of Venus and cause hypervelocity impact craters on the planet's surface. Using scaling relationships based on kinetic energy, impact crater size is related to meteoroid size. Finally, it is determined that the smallest impact craters that might exist on Venus are on the order of 150 to 300 meters in diameter.

Tauber, M. E.↗