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NASA NTRS1985

Effect of superconducting solenoid model cores on spanwise iron magnet roll control

Compared with conventional ferromagnetic fuselage cores, superconducting solenoid cores appear to offer significant reductions in the projected cost of a large wind tunnel magnetic suspension and balance system. The provision of sufficient magnetic roll torque capability has been a long-standing problem with all magnetic suspension and balance systems; and the spanwise iron magnet scheme appears to be the most powerful system available. This scheme utilizes iron cores which are installed in the wings of the model. It was anticipated that the magnetization of these cores, and hence the roll torque generated, would be affected by the powerful external magnetic field of the superconducting solenoid. A preliminary study has been made of the effect of the superconducting solenoid fuselage model core concept on the spanwise iron magnet roll torque generation schemes. Computed data for one representative configuration indicate that reductions in available roll torque occur over a range of applied magnetic field levels. These results indicate that a 30-percent increase in roll electromagnet capacity over that previously determined will be required for a representative 8-foot wind tunnel magnetic suspension and balance system design.

Britcher, C. P.↗

NASA NTRS1975

Light element geochemistry of the Apollo 16 site

The abundance and isotopic composition of carbon, sulfur, and nitrogen, the abundance of helium and hydrogen, and the content of metallic iron are reported for lunar surface samples from the Apollo 16 landing site at Cayley-Descartes. The light elements show marked interstation variability at the site. The abundances in soils of C, N, He, and H are apparently controlled mainly by exposure to the solar wind, through implantation or stripping processes. Carbon abundances (but not observed isotopic distributions) are compatible with a model in which equilibrium is established after 10,000-100,000 yr between solar wind input and loss by proton stripping. Sulfur abundances in soils are apparently controlled by abundances in local country rocks, but the lunar S cycle is quite complex. A metallic iron component may have originated by solar wind reduction of lunar Fe(2+).

Kerridge, J. F.↗

NASA NTRS2012

Effects of High Dietary HEME Iron and Radiation on Cardiovascular Function

The radiation related health risks to astronauts is of particular concern to NASA. Data support that exposure to radiation is associated with a number of disorders including a heightened risk for cardiovascular diseases. Independent of radiation, altered nutrient status (e.g. high dietary iron) also increases ones risk for cardiovascular disease. However, it is unknown whether exposure to radiation in combination with high dietary iron further increases ones cardiovascular risk. The intent of our proposal is to generate compulsory data examining the combined effect of radiation exposure and iron overload on sensitivity to radiation injury to address HRP risks: 1) Risk Factor of Inadequate Nutrition; 2) Risk of Cardiac Rhythm Problems; and 3) Risk of Degenerative Tissue or other Health Effects from Space Radiation. Towards our goal we propose two distinct pilot studies using the following specific aims: Vascular Aim 1: To determine the short-term consequences of the independent and combined effects of exposure to gamma radiation and elevated body iron stores on measures of endothelial function and cell viability and integrity. We hypothesize that animals that have high body iron stores and are exposed to gamma radiation will show a greater reduction in endothelial dependent nitric oxid production and larger pathological changes in endothelial integrity than animals that have only 1 of those treatments (either high iron stores or exposure to gamma radiation). Vascular Aim 2: Identify and compare the effects of gamma radiation and elevated body iron stores on the genetic and epigenetic regulation of proteins associated with endothelial cell function. We hypothesize that modifications of epigenetic control and posttranslational expression of proteins associated with endothelial cell function will be differentially altered in rats with high body iron stores and exposed to gamma radiation compared to rats with only 1 type of treatment. Cardiac Aim 1: To determine the short-term consequences of the independent and combined effects of gamma radiation and elevated body iron stores on measures of cardiac structure. We hypothesize that modifications to cardiac structure and function will be greater in rats with high body iron stores and exposed to gamma radiation than in rats that have only 1 of those treatments. Cardiac Aim 2: Identify and compare the effects of gamma radiation and elevated body iron stores on the genetic and epigenetic regulation of proteins associated with cardiac structure and function. We hypothesize that modifications of epigenetic control and posttranslational expression of proteins associated with cardiac contractile function will be differentially altered in rats with high body iron stores and exposed to gamma radiation compared to rats with only 1 type of treatment.

Westby, Christian M.↗

NASA NTRS2013

Lunar Sulfur Capture System

The Lunar Sulfur Capture System (LSCS) protects in situ resource utilization (ISRU) hardware from corrosion, and reduces contaminant levels in water condensed for electrolysis. The LSCS uses a lunar soil sorbent to trap over 98 percent of sulfur gases and about two-thirds of halide gases evolved during hydrogen reduction of lunar soils. LSCS soil sorbent is based on lunar minerals containing iron and calcium compounds that trap sulfur and halide gas contaminants in a fixed-bed reactor held at temperatures between 250 and 400 C, allowing moisture produced during reduction to pass through in vapor phase. Small amounts of Earth-based polishing sorbents consisting of zinc oxide and sodium aluminate are used to reduce contaminant concentrations to one ppm or less. The preferred LSCS configuration employs lunar soil beneficiation to boost concentrations of reactive sorbent minerals. Lunar soils contain sulfur in concentrations of about 0.1 percent, and halogen compounds including chlorine and fluorine in concentrations of about 0.01 percent. These contaminants are released as gases such as H2S, COS, CS2,HCl, and HF during thermal ISRU processing with hydrogen or other reducing gases. Removal of contaminant gases is required during ISRU processing to prevent hardware corrosion, electrolyzer damage, and catalyst poisoning. The use of Earth-supplied, single-use consumables to entirely remove contaminants at the levels existing in lunar soils would make many ISRU processes unattractive due to the large mass of consumables relative to the mass of oxygen produced. The LSCS concept of using a primary sorbent prepared from lunar soil was identified as a method by which the majority of contaminants could be removed from process gas streams, thereby substantially reducing the required mass of Earth-supplied consumables. The LSCS takes advantage of minerals containing iron and calcium compounds that are present in lunar soil to trap sulfur and halide gases in a fixedbed reactor downstream of an in-ISRU process such as hydrogen reduction. The lunar-soil-sorbent trap is held at a temperature significantly lower than the operating temperature of the hydrogen reduction or other ISRU process in order to maximize capture of contaminants, but is held at a high enough temperature to allow moisture to pass through without condensing. The lunar soil benefits from physical beneficiation to remove ultrafine particles (to reduce pressure drop through a fixed bed reactor) and to upgrade concentrations of iron and/or calcium compounds (to improve reactivity with gaseous contaminants).

Berggren, Mark↗

NASA NTRS1991

Hydrogen reduction mechanisms of ilmenite between 823 and 1353 K

In situ gravimetric measurements and microscopic examinations were used to determine the mechanisms of oxygen removal from synthetic ilmenite disks between 823 and 1353 K. Under a hydrogen atmosphere, iron was observed to form a layer of low porosity on the surface of samples early in the reduction. This created diffusion limitations for hydrogen to the reaction front and for the escape of water vapor. A shrinking core reduction model, modified to include the growth of this iron film, was capable of predicting the conversion-time relationships of ilmenite samples. An activation energy of 43.2 +/- 2.6 kcal/gmole was determined to be representative of reaction control over the temperature range 823-1023 K.

Briggs, R. A.↗

NASA NTRS1979

Microbial Sulfate Reduction Measured by an Automated Electrical Impedance Technique

Electrical impedance measurements are used to investigate the rates of sulfate reduction by pure cultures of and sediments containing sulfur-reducing bacteria. Changes in the electrical impedance ratios of pure cultures of Desulfovibrio aestuarii and samples of reduced sediments from San Francisco Bay were measured by a Bactometer 32, and sulfate reduction was followed by measuring the incorporation of (S-35) sulfate into metal sulfides. The growth of the bacteria in pure culture is found to result in an increase of 0.2200 in the impedance ratio within 24 h, accompanied by increases in protein, ATP, sulfide and absorptance at 660 nm, all of which are inhibited by the addition of molybdate. Similar responses were observed in the sediments, although impedance ratio responses were not completely inhibited upon the addition of molybdate, due to the presence of nonsulfate-respiring microorganisms. Experiments conducted with sterile media and autoclaved sediments indicate that the presence of H2S together with iron is responsible for the impedance effect, and sulfate reduction rates ranging between 0.85 and 1.78 mmol/l per day are estimated for the sediments by the impedance technique.

Oremland, R. S.↗

NASA NTRS1996

Observations of Two Non-Standard Grain Components

We discuss evidence for two non-standard grain components: small conglomerates and astronomical iron. The small conglomerates are small, temperature fluctuating grains made up of loosely bound 12 micron emitters (either PAH's or dielectrics). When these grains are exposed to strong UV radiation fields they break apart into smaller pieces. For high UV radiation regimes, such as H II regions, conglomerate grains best explain the reduction of 25 micron emission relative to 12 micron. Astronomical iron was originally proposed for isolated cirrus clouds in order to account for the strength of the 60 micron emission. Within the diffuse ISM, these grains emit at a relatively high equilibrium temperature of 50 K. Our analysis of IRAS data shows the presence of a strong 60 micron emitter in the Lambda Orionis H II region and a component within the Rosette Nebula emitting primarily at 25 micron. Both of these observations can be accommodated by the presence of iron grains within the H II regions.

Shipman, R. F.↗

NASA NTRS2002

Red blood cell and iron metabolism during space flight

Space flight anemia is a widely recognized phenomenon in astronauts. Reduction in circulating red blood cells and plasma volume results in a 10% to 15% decrement in circulatory volume. This effect appears to be a normal physiologic adaptation to weightlessness and results from the removal of newly released blood cells from the circulation. Iron availability increases, and (in the few subjects studied) iron stores increase during long-duration space flight. The consequences of these changes are not fully understood.

STS Shuttle Project↗

NASA NTRS2000

Nonbiological fractionation of iron isotopes

Laboratory experiments demonstrate that iron isotopes can be chemically fractionated in the absence of biology. Isotopic variations comparable to those seen during microbially mediated reduction of ferrihydrite are observed. Fractionation may occur in aqueous solution during equilibration between inorganic iron complexes. These findings provide insight into the mechanisms of iron isotope fractionation and suggest that nonbiological processes may contribute to iron isotope variations observed in sediments.

NASA Discipline Exobiology↗

NASA NTRS1972

Investigation of a possible solar-wind darkening of the lunar surface by photoelectron spectroscopy.

Detailed sequential study by photoelectron spectroscopy of the change in valence states of iron in Fe2O3, Fe3O4, FeO, and Fe foil samples, showing that chemical reduction does take place on the sample surface when argon ion bombardment occurs. These spectra give evidence that, after prolonged ion bombardment, the surface of all four samples consisted predominantly of iron in the metallic state. Argon ion sputtering of 15 silicate and oxide samples under similar experimental conditions produced surface darkening only in samples containing iron. Monitoring of the photoelectron peak of carbon during the experiment indicates that ion-bombardment darkening is not due to the buildup of hydrocarbon surface contaminants in the oil-free high-vacuum system used by the authors. On the basis of these studies, it is concluded that solar-wind bombardment should be included as one of the possible mechanisms for producing darkening of the lunar surface.

Yin, L. I.↗

NASA NTRS2003

Small, Untethered, Mobile Robots for Inspecting Gas Pipes

Small, untethered mobile robots denoted gas-pipe explorers (GPEXs) have been proposed for inspecting the interiors of pipes used in the local distribution natural gas. The United States has network of gas-distribution pipes with a total length of approximately 109 m. These pipes are often made of iron and steel and some are more than 100 years old. As this network ages, there is a need to locate weaknesses that necessitate repair and/or preventive maintenance. The most common weaknesses are leaks and reductions in thickness, which are caused mostly by chemical reactions between the iron in the pipes and various substances in soil and groundwater. At present, mobile robots called pigs are used to inspect and clean the interiors of gas-transmission pipelines. Some carry magnetic-flux-leakage (MFL) sensors for measuring average wall thicknesses, some capture images, and some measure sizes and physical conditions. The operating ranges of pigs are limited to fairly straight sections of wide transmission- type (as distinguished from distribution- type) pipes: pigs are too large to negotiate such obstacles as bends with radii comparable to or smaller than pipe diameters, intrusions of other pipes at branch connections, and reductions in diameter at valves and meters. The GPEXs would be smaller and would be able to negotiate sharp bends and other obstacles that typically occur in gas-distribution pipes.

Wilcox, Brian↗

NASA NTRS1974

Texturing and residual stress in metals as a result of sliding

Pole figures of the texturing produced by friction in the alloys Cu - 10 at. % Sn, Cu - 10 at. % Si, 440 C stainless steel, and AISI 52100 bearing steel were obtained with an energy-dispersive X-ray diffractometer. While the texturing behavior of these alloys is generally similar to that of pure metals, the 52100 steel and the Cu5Si phase of Cu - 10 at. % Si show no texturing at the loads and speeds used in this experiment. Photographic methods were used in an attempt to measure the uniform residual stress in the wear tracks produced on some pure metals. The stress in copper and iron was, however, below the limit of detectability - about 4.3 x 10 to the 7th power N/sq m (6000 psi). Line broadening under all test conditions in the case of copper and at high load and speed conditions in iron is attributed, at least in part, to the reduction of crystallite size and, perhaps, to nonuniform residual stress, as well.

Wheeler, D. R.↗

NASA NTRS1976

The Redox Flow System for solar photovoltaic energy storage

The interfacing of a Solar Photovoltaic System and a Redox Flow System for storage was workable. The Redox Flow System, which utilizes the oxidation-reduction capability of two redox couples, in this case iron and titanium, for its storage capacity, gave a relatively constant output regardless of solar activity so that a load could be run continually day and night utilizing the sun's energy. One portion of the system was connected to a bank of solar cells to electrochemically charge the solutions, while a separate part of the system was used to electrochemically discharge the stored energy.

Odonnell, P.↗

NASA NTRS2005

Workshop on Oxygen in Asteroids and Meteorites

Contents include the following: Constraints on the detection of solar nebula's oxidation state through asteroid observation. Oxidation/Reduction Processes in Primitive Achondrites. Low-Temperature Chemical Processing on Asteroids. On the Formation Location of Asteroids and Meteorites. The Spectral Properties of Angritic Basalts. Correlation Between Chemical and Oxygen Isotopic Compositions in Chondrites. Effect of In-Situ Aqueous Alteration on Thermal Model Heat Budgets. Oxidation-Reduction in Meteorites: The Case of High-Ni Irons. Ureilite Atmospherics: Coming up for Air on a Parent Body. High Temperature Effects Including Oxygen Fugacity, in Pre-Planetary and Planetary Meteorites and Asteroids. Oxygen Isotopic Variation of Asteroidal Materials. High-Temperature Chemical Processing on Asteroids: An Oxygen Isotope Perspective. Oxygen Isotopes and Origin of Opaque Assemblages from the Ningqiang Carbonaceous Chondrite. Water Distribution in the Asteroid Belt. Comparative Planetary Mineralogy: V Systematics in Planetary Pyroxenes and fo 2 Estimates for Basalts from Vesta.

Source record↗

NASA NTRS2002

Studying the Iron Line Complex in the Bright Seyfert Galaxy NGC 5506

This grant was to support the reduction and analysis of our approved XMM observation of the nearby Seyfert 2 galaxy NGC 5506. The observation has been carried out simultaneously with a BeppoSAX observation of the same source. The proposal was aimed to study in detail the Compton reflection component and the complex Iron K line of this source, combining the still unique capability of BeppoSAX in hard X-rays (to strongly constrain the reflection component, and then the intrinsic nuclear continuum), and the sensitivity of XMM at the energy of the Iron Line complex. NGC 5506 is one of the brightest AGN in hard X-rays and has been intensively studied in the past. GINGA detected the complex iron line as well as the reflection component. Both ASCA (spectroscopically) and Rossi-XTE (through variability analysis) suggested that the FeK line is complex, possibly made up of several distinct components. The centroid of the FeK complex in a subsequent BeppoSAX observation was bluer than the 6.4 keV energy of the relatively low-ionization iron Kalpha transition. NGC 5506 has been observed simultaneously by NewtonXMM and BeppoSAX on February 2-3 2001. we have reduced and analyzed both the NewtonXMM and the BeppoSAX data, and have written and published a paper on our results (appeared in Volume 377 (page 31) of A&A-Letters). Our main results can be summarized as follows: (a) we confirm that the FeK line is complex, and for the first time disentangle its components: we find that at least two components made up the FeK complex, one neutral and narrow, at 6.4 keV (rest energy), and another one either broader and highly ionized, at about 6.7 keV (rest frame), or, in turn, made up of two narrow and unresolved components from the He-like and the H-like ions of Fe; (b) the two possible solution for the high-ionization Fe-K component, are statistically indistinguishable. However, physically, a blend of two narrow lines from photoionized matter seems to be preferable to emission of a relativistically broadened line from an ionized accretion disk; (c) The bulk of the Compton reflection continuum originates in neutral matter, and is therefore associated with the narrow FeK line at 6.4 keV: they are most likely emitted by distant matter.

Nicastro, Fabrizio↗

NASA NTRS2004

Fe-57 Moessbauer Spectroscopy of Fulgurites: Implications for Chemical Reduction

The high temperature (superliquidus) processing of silicates often results in very reduced products, such as Si-bearing Fe metal in type-1 chondrules and in lunar regolith agglutinates. Previous work on fulgurites (the glassy products of the lightning strike fusion of sand, soil, or rock) found silicon metal and iron-silicon alloys inside the silicate glass. The mechanism for this extreme reduction is not yet understood. In this work, we begin a Fe-57 Moessbauer spectroscopy study as well as continuing a microprobe study of several fulgurites in order to better constrain the extent and process of Fe reduction.

Sheffer, A. A.↗

NASA NTRS1991

An empirical approach to predicting long term behavior of metal particle based recording media

Alpha iron particles used for magnetic recording are prepared through a series of dehydration and reduction steps of alpha-Fe2O3-H2O resulting in acicular, polycrystalline, body centered cubic (bcc) alpha-Fe particles that are single magnetic domains. Since fine iron particles are pyrophoric by nature, stabilization processes had to be developed in order for iron particles to be considered as a viable recording medium for long term archival (i.e., 25+ years) information storage. The primary means of establishing stability is through passivation or controlled oxidation of the iron particle's surface. Since iron particles used for magnetic recording are small, additional oxidation has a direct impact on performance especially where archival storage of recorded information for long periods of time is important. Further stabilization chemistry/processes had to be developed to guarantee that iron particles could be considered as a viable long term recording medium. In an effort to retard the diffusion of iron ions through the oxide layer, other elements such as silicon, aluminum, and chromium have been added to the base iron to promote more dense scale formation or to alleviate some of the non-stoichiometric behavior of the oxide or both. The presence of water vapor has been shown to disrupt the passive layer, subsequently increasing the oxidation rate of the iron. A study was undertaken to examine the degradation in magnetic properties as a function of both temperature and humidity on silicon-containing iron particles between 50-120 deg C and 3-89 percent relative humidity. The methodology to which experimental data was collected and analyzed leading to predictive capability is discussed.

Hadad, Allan S.↗

NASA NTRS1992

An empirical approach to predicting long term behavior of metal particle based recording media

Hadad, Allan S.↗