Engineering topics

Rietmeijer, F. J. M.

Publications and source records attributed to Rietmeijer, F. J. M..

At least 19 records

NASA NTRS2004

Major and Trace Element Variations in Impact Crater Clay from Chicxulub, Lonar, and Mistastin, Implications for the Martian Soil

The catastrophic Chicxulub event should have generated a large hydrothermal system with volatile element mobilization, producing interesting alteration materials and clays. The Yaxcopoil-1 (YAX) drill hole is located in the annular trough, about 70 km southwest of the crater center, in an area where the impactite layers are relatively thin (approx. 100 m thick). We have analyzed samples from the YAX drill core and from other impact craters including Mistastin and Lonar to determine the nature of alteration and trace element mobilization.

Newsom, H. E.↗

NASA NTRS2004

First Report of Taenite in an Asteroidal Interplanetary Dust Particle: Flash-heating Simulates Nebular Dust Evolution

Metallic iron with a taenite structure rimmed by Fe3C carbide, kamacite with a magnetite rim, both approximately 200 nm in size, and les than 15 nm kamacite crystals embedded in equilibrated aggregates (or GEMS) were reported in IDPs. Here I report the first g-(Fe,Ni), taenite, in sulfide fragment -F6 particle with adhered patches of thermally modified aggregate IDP-like material belonging to cluster IDP L2011#21.

Rietmeijer, F. J. M.↗

NASA NTRS2002

Thermal Modification of Silicate Materials on Flash-heated Sulfide IDPs: The First Clues for Chemically Controlled, Early Silicate Mineral Evolution

Variable Ca-compositions of flash heated ferromagnesiosilica materials on massive sulfide IDPs provide the first clues for chemically controlled nucleation of pyroxenes during the earliest stages of silicate mineral evolution in solar nebula dust. Additional information is contained in the original extended abstract.

Rietmeijer, F. J. M.↗

NASA NTRS2001

Serpentine by Hydrogenation of Fe-rich Ferromagnesiosilica PCs in Aggregate IDPs

Condensed hydrogen-bearing magnesiosilica smokes support that hydrogenation at H2/H2O ratios may lead to the formation of rare Fe-rich serpentine plus metallic iron in ferromagnesiosilica PCs with appropriate (Mg,Fe)/Si ratios that were acquired during their formation. Additional information is contained in the original extended abstract.

Rietmeijer, F. J. M.↗

NASA NTRS2001

Heat-Treatment of MgSiO Smokes of Astrophysical Interest: Possible Implications for Olivine-Pyroxene-Silica Assemblages in Chondritic Aggregate IDPs

Anhydrous silicates in coarse-grained ferromagnesiosilica principal components (PCs) formed during atmospheric entry flash-heating also constrain the astromineralogy of astrophysical dust. This is because of the unique closed-system behavior of these PCs in chondritic aggregate interplanetary dust particles (IDPs). Additional information is contained in the original extended abstract.

Rietmeijer, F. J. M.↗

NASA NTRS1999

Nucleation, Growth, Annealing, and Coagulation of Refractory Oxides and Metals: Recent Experimental Progress and Applications to Astrophysical Systems

Starting with cooling, refractory vapors diluted in significant quantities of H and He there are four processes that most natural systems will undergo: nucleation, growth, annealing, and coagulation. Nucleation is the processes by which the first stable refractory nuclei form in the vapor. These are the seeds onto which the remaining vapors will condense during the growth stage. Solids of any composition will try to arrange themselves into the least energetic configuration, provided that there is sufficient energy available to support such processes as diffusion and the breaking of chemical bonds. There is a significant activation energy associated with the annealing process in refractory solids due to the relatively high energy of the chemical bonds in solids. The grains formed in most cosmochemical systems are extremely small and often tightly coupled to the gas. Because of their small physical cross sections coagulation may be a very slow process unless there is another driving force involved in addition to normal Brownian motion. In what follows we will briefly cover each of these four stages for refractory oxide and metal grains, although in inverse order.

Nuth, J. A.↗

NASA NTRS1991

Tridymite and maghemite formation in an Fe-SiO smoke

Grains produced in porous Fe-SiO smoke are analyzed by means of electron microscopy to determine their crystallographical, morphological, and chemical properties. The nucleation of metal oxide condensates takes place as the vapor evolves in a condensation-flow apparatus, initially producing simple crystalline phases. Fe nucleation follows, and the subsequent heterogeneous nucleation of quenched mixed high-Fe silica grains exhibits associated Fe-depletion, eventually producing pure silica grains. The coalescence exhibited by the pure silica grains is compatible with the higher surface energy found in the pure silica phase. During coagulation the grains melt and anneal to a chemically pure mixture of alpha- and beta-tridymite, and the precipitation of amorphous silica material is observed. The settling of grains in evolving solar nebula is theorized to be related to the stickiness of this material, and maghemite is suggested to contribute to the Fe/Si fractionation in solar nebula.

Rietmeijer, F. J. M.↗

NASA NTRS1989

Ultrafine-grained mineralogy and matrix chemistry of olivine-rich chondritic interplanetary dust particles

Olivine-rich chondritic interplanetary dust particles (IDPs) are an important subset of fluffy chondritic IDPs collected in the earth's stratosphere. Particles in this subset are characterized by a matrix of nonporous, ultrafine-grained granular units. Euhedral single crystals, crystals fragments, and platey single crystals occur dispersed in the matrix. Analytical electron microscopy of granular units reveals predominant magnesium-rich olivines and FeNi-sulfides embedded in amorphous carbonaceous matrix material. The variable ratio of ultrafine-grained minerals vs. carbonaceous matrix material in granular units support variable C/Si ratios, and some fraction of sulfur is associated with carbonaceous matrix material. The high Mg/(Mg+Fe) ratios in granular units is similar to this distribution in P/Comet Halley dust. The chondritic composition of fine-grained, polycrystalline IDPs gradually breaks down into nonchondritic, and ultimately, single mineral compositions as a function of decreased particle mass. The relationship between particle mass and composition in the matrix of olivine-rich chondritic IDPs is comparable with the relationship inferred for P/Comet Halley dust.

Rietmeijer, F. J. M.↗

NASA NTRS1987

Kinetics in a turbulent nebular cloud

Model calculations, which include the effects of turbulence during subsequent solar nebula evolution after the collapse of a cool interstellar cloud, can reconcile some of the apparent differences between physical parameters obtained from theory and the cosmochemical record. Two important aspects of turbulence in a protoplanetary cloud include the growth and transport of solid grains. While the physical effects of the process can be calculated and compared with the probable remains of the nebula formulation period, the more subtle effects on primitive grains and their survival in the cosmochemical record cannot be readily evaluated. The environment offered by the Space Station (or Space Shuttle) experimental facility can provide the vacuum and low gravity conditions for sufficiently long time periods required for experimental verification of these cosmochemical models.

Mackinnon, Ian D. R.↗

NASA NTRS1986

Nucleation experiments in a microgravity environment

A simple experimental apparatus is described in which a wide variety of vapor phase nucleation studies of refractory materials could be performed aboard NASA's KC-135 Research Aircraft. The chief advantage of a microgravity environment for these studies is the expected absence of thermally driven convective motions in the gas. The absence of convection leads to much more accurate knowledge of both the temperature distribution in the system and the time evolution of the refractory vapor concentration as a function of distance from the crucible.The evolution of the apparatus will be described as more experience is gained with the microgravity environment. Such experiments will be used to prepare for similar ones carried out aboard either the shuttle or Space Station where considerably longer duration experiments are possible.

Nuth, J. A.↗

NASA NTRS1986

Analytical electron microscopy of Mg-SiO smokes - A comparison with infrared and XRD studies

Analytical electron microscopy conducted for Mg-SiO smokes (experimentally obtained from samples previously characterized by IR spectroscopy) indicates that the microcrystallinity content of unannealed smokes increases with increased annealing for up to 30 hr. The growth of forsterite microcrystallites in the initially nonstoichiometric smokes may give rise to the contemporaneous growth of the SiO polymorph tridymite and MgO; after 4 hr of annealing, these react to form enstatite. It is suggested that XRD analysis and IR spectroscopy should be conducted in conjunction with detailed analytical electron microscopy for the detection of emerging crystallinity in vapor-phase condensates.

Rietmeijer, F. J. M.↗

NASA NTRS1986

What predictions can be made on the nature of carbon and carbon-bearing compounds (hydrocarbons) in the interstellar medium based on studies of interplanetary dust particles?

The nature of hydrocarbons and properties of elemental carbon in circumstellar, interstellar, and interplanetary dust is a long standing problem in astronomy and meteorite research. The textures and crystallographical properties of poorly graphitized carbon (PGC) from carbonaceous chondrites and Chondritic Porous Aggregates (CPAs) are comparable with PGCs formed by dehydrogenation and carbonization of hydrocarbon precursors under natural terrestrial and experimental conditions. A multistage model of hydrocarbon diagenesis in CPA and carbonaceous chondrite (proto-) planetary parent bodies was proposed in which hydrocarbons are subjected to low temperature hydrous pyrolysis. Continued efforts to recognize hydrocarbons and elemental phases in CPAs may allow understanding of the multistage hydrocarbon/elemental carbon model.

Rietmeijer, F. J. M.↗

NASA NTRS1986

Metastable carbon in two chondritic porous interplanetary dust particles

An understanding of carbonaceous matter in primitive extraterrestrial materials is an essential component of studies on dust evolution in the interstellar medium and the early history of the Solar System. Analytical Electron Microscopy (AEM) on carbonaceous material in two Chondritic Porous (CP) aggregrates is presented. The study suggests that a record of hydrocarbon carbonization may also be preserved in these materials.

Rietmeijer, F. J. M.↗

NASA NTRS1986

The solar maximum satellite capture cell: Impact features and orbital debris and micrometeoritic projectile materials

The physical properties of impact features observed in the Solar Max main electronics box (MEB) thermal blanket generally suggest an origin by hypervelocity impact. The chemistry of micrometeorite material suggests that a wide variety of projectile materials have survived impact with retention of varying degrees of pristinity. Impact features that contain only spacecraft paint particles are on average smaller than impact features caused by micrometeorite impacts. In case both types of materials co-occur, it is belevied that the impact feature, generally a penetration hole, was caused by a micrometeorite projectile. The typically smaller paint particles were able to penetrate though the hole in the first layer and deposit in the spray pattern on the second layer. It is suggested that paint particles have arrived with a wide range of velocities relative to the Solar Max satellite. Orbiting paint particles are an important fraction of materials in the near-Earth environment. In general, the data from the Solar Max studies are a good calibration for the design of capture cells to be flown in space and on board Space Station. The data also suggest that development of multiple layer capture cells in which the projectile may retain a large degree of pristinity is a feasible goal.

Mckay, D. S.↗

NASA NTRS1986

The importance of capturing unmodified chondritic porous micrometeorites on the space station

The survival of interplanetary dust particles (IDP's) during deceleration by the Earth's atmosphere is determined by their entry parameters, velocity, size and mass. These IDP's reach their terminal velocity at about 55 to 95 km altitude before they gradually settle to 18 to 21 km altitude where they are collected by high flying aircraft. Chondritic porous IDP's (also called chondritic porous (CP) aggregates) show properties consistent with an extraterrestrial origin. It is conceivable that CP aggregates may be collected above the Earth's atmosphere using capture devices on a space station or satellite. In order to preserve pristine CP aggregates, i.e., aggregates with minimal perturbation or degradation of its particulate matter, it is necessary to transfer the kinetic energy on impact so that a minimum amount of energy is dissipated into the impacting particle. It is likely that low-temperature minerals (e.g., layer silicates), volatile phases (e.g., sulfides), structural defects (e.g. nuclear tracks) and hydrocarbons in CP aggregates are sensitive to the efficiency of kinetic energy dissipation.

Rietmeijer, F. J. M.↗

NASA NTRS1986

An inadvertent capture cell for orbital debris and micrometeorites - The main electronics box thermal blanket of the solar maximum satellite

The physical properties of impact features in the Solar Max main electronics box thermal blanket are consistent with hypervelocity impacts of particles in the near-earth space environment. The majority of particles are orbital debris and include spacecraft paints and bismuth-rich particles. At least 30 percent of all impact features are caused by micrometeorites, which include silicates and sulfides. Some micrometeorites survive impact with only minor shock-metamorphic effects or chemical fractionation. Currently calibration experiments are under way to relate flux to particle diameter (or mass).

Rietmeijer, F. J. M.↗

NASA NTRS1985

Layer silicates in a chondritic porous interplanetary dust particle

Analytical electron microscopy on individual grains from a portion of a chondritic porous interplanetary dust particle (aggregate W7029C1 from the NASA Johnson Space Center Cosmic Dust Collection) shows that layer silicates compose 50 percent of the silicate fraction examined. These layer silicates can be classified into two distinct crystallochemical groups: (1) fine-grained, polycrystalline smectite minerals; and (2) well-ordered, single crystals of kaolinite and Mg-poor talc. The layer silicates in this portion of sample W7029(asterisk)A are dissimilar to those described in other chondritic porous aggregates. The predominant layer silicate assemblage in W7029(asterisk)A indicates that heating of the aggregate during atmospheric entry was brief and probably to a temperature less than 300 C. Comparison with terrestrial phyllosilicate occurrences suggests that some layer silicates in aggregate W7029(asterisk)A may have been formed by alteratiton from preexisting silicate minerals at low temperatures (less than 25 C) after aggregate formation.

Rietmeijer, F. J. M.↗

NASA NTRS1985

Poorly graphitized carbon as a new cosmothermometer for primitive extraterrestrial materials

A description is presented for the most common carbon phase in carbon-rich chondritic porous (CP) aggregate collected from the stratosphere by NASA researchers as part of the Cosmic Dust Program. An extraterrestrial origin was confirmed for the samples by microscopic examinations. The sample grains contained 45 percent carbon-rich phases and 30 percent low-temperature phases. Studies of the d002 interlayer spacing of the carbon clumps indicated that graphitization occurred at metamorphic temperatures after solar nebular condensation, yet early in solar system formation. Graphitized terrestrial materials served as a useful reference against which the CP materials were compared.

Rietmeijer, F. J. M.↗