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All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Labile and nonlabile element relationships among Apollo 17 samples

Volatile and nonvolatile trace element contents in a suite of Apollo 17 soils and rocks are studied. It is found that the halogens exhibit a remarkable degree of coherence because of their apparent diverse geochemistry, that the F-Cl-P2O5 coherence previously noted persists among Apollo 17 samples, that both U and Ru-Os support lateral mixing of regolith on a local scale, and that the meteoritic Ru/Os ratios found in a few samples are attributed to primitive lunar material that has not been extensively recycled.

Jovanovic, S.↗
NASA NTRS1975

Size and modal analyses of fines and ultrafines from some Apollo 17 samples

Scanning electron and optical microscopy techniques have been used to determine the grain-size frequency distributions and morphology-based modal analyses of fine and ultrafine fractions of some Apollo 17 regolith samples. There are significant and large differences between the grain-size frequency distributions of the less than 10-micron size fraction of Apollo 17 samples, but there are no clear relations to the local geologic setting from which individual samples have been collected. This may be due to effective lateral mixing of regolith particles in this size range by micrometeoroid impacts. None of the properties of the frequency distributions support the idea of selective transport of any fine grain-size fraction, as has been proposed by other workers. All of the particle types found in the coarser size fractions also occur in the less than 10-micron particles. In the size range from 105 to 10 microns there is a strong tendency for the percentage of regularly shaped glass to increase as the graphic mean grain size of the less than 1-mm size fraction decreases, both probably being controlled by exposure age.

Greene, G. M.↗
NASA NTRS1982

The lunar regolith - Comparative studies of the Apollo and Luna sites. Petrology of soils from Apollo 17, Luna 16, 20, and 24

A progress report is presented concerning an investigation involving a comprehensive chemical and petrologic study of surface soils from all nine lunar sampling sites. The soils selected for this study are part of the lunar highlands soils suite and represent the soils at each site that contain abundant highland-derived material. The current report takes into consideration, in addition to the eight soils discussed by Labotka et al. (1980) and by Laul and Papike (1980), three Apollo 17 soils (72501, 76501, and 78221), and three Luna soils (21000, L-16; 22001, L-20; and 24999, L-24). Attention is given to the modal petrology of the 1000-90 micrometer fraction of all 14 soils, and the modes and mineral and glass chemistries of the 90-20 and 20-10 micrometer fractions of the Apollo 17 and Luna soils. In an evaluation of the obtained results, it is found that except for rare, large-scale impacts, lateral mixing is an inefficient process. Comminution and vertical mixing appear to be the dominant process.

Simon, S. B.↗
NASA NTRS1986

Eddy processes in the general circulation of the Jovian atmospheres

Two fundamentally different views of the general circulation of Jovian atmospheres have emerged. According to one view, the observed jet streams at the cloud tops are controlled by the vorticity transfers of small scale eddies generated by planetary wave instabilities within a shallow atmospheric layer. According to the alternate point of view, the zonal jets are surface manifestations of deep interior convection organized into cylindrical motion with axes parallel to the planetary rotation axis. Both approaches may be considered in the context of the very different roles assumed by the potential vorticity. A possible reconciliation of the two kinds of dynamical systems is considered in which the interior motion is overlaid with a statically stable cappling layer driven by turbulent energy injection from below. A simple model for the eddy driving of quasi-geostrophic dynamics in the capping layer is presented which is consistent with the tentative evidence for up-gradient momentum flux on Jupiter and IRIS observations of thermal contrast correlations with cyclonic and anticyclonic shear zones. Certain synoptic-scale cloud features in Jupiter's atmosphere are interpreted as breaking waves, which may also influence the lateral mixing of tracers such as the ortho-para hydrogen ratio.

Leovy, Conway↗
NASA NTRS2005

The Lunar-wide Effects of the Formation of Basins on the Megaregolith

The surface of the Moon underwent an intense bombardment during the first approx.700 my of it s history (e.g. [1]). During this time at least 43 basins [1,2] and countless smaller craters were formed across the entire surface [1,3]. A quantitative assessment of the regolith as formed and modified by basins is discussed here. The formation of the basins (craters >300km in diameter) caused a significant amount of material to be excavated and redistributed across the surface of the Moon [4,5,6,7]. The material excavated by each individual basin was deposited and laterally mixed with the surrounding surface. This resulted in the development of a lunar-wide mixed zone of fragmented material, several kilometers thick [5,8,9]. This mixed zone was developed further by subsequent impacts resulting in a fragmental zone 1-2km thick called the megaregolith [10]. The initial zone of mixed material formed by the basins is not expected to be uniform across the surface of the Moon because of the varied size and random distribution of the basins. The main topographic ring of the 43 basins discussed by Wilhelms and Spudis [1,2] are illustrated in Figure 1.

Petro, . E.↗
NASA NTRS2010

Pulling Marbles from a Bag: Deducing the Regional Impact History of the SPA Basin from Impact-Melt Rocks

The South Pole Aitken (SPA) basin is the stratigraphically oldest identifiable lunar basin and is therefore one of the most important targets for absolute age-dating to help understand whether ancient lunar bombardment history smoothly declined or was punctuated by a cataclysm. A feasible near-term approach to this problem is to robotically collect a sample from near the center of the basin, where vertical and lateral mixing provided by post-basin impacts ensures that such a sample will be composed of small rock fragments from SPA itself, from local impact craters, and from faraway giant basins. The range of ages, intermediate spikes in the age distribution, and the oldest ages are all part of the definition of the absolute age and impact history recorded within the SPA basin.

Cohen, Barbara A.↗
NASA NTRS1974

The relationships between geology and soil chemistry at the Apollo 17 landing site

Within the wide compositional range of the Apollo 17 soils, three distinct chemical groups have been recognized, each one corresponding broadly with a major geological and physiographic unit. These groups are: (1) Valley Floor type soils, (2) South Massif type soils, and (3) North Massif type soils. The observed chemical variations within and between these three groups is interpreted by means of mixing models in terms of lateral transport and mixing of prevailing local rock types, such as high-titanium basalts, KREEP-like noritic breccias, anorthositic gabbro breccias and orange glass. According to these models, North Nassif types evolved on the lower slopes of the North Massif and Sculptured Hills where anorthositic gabbro predominates over noritic breccia and where lateral mixing with basalt is effective, whereas the South Massif type soils originally developed on the upper slopes of the South Massif, where anorthositic breccia and noritic breccias are equally abundant, and where lateral mixing with basalt was minimal.

Rhodes, J. M.↗
NASA NTRS1977

Comparison of orbital chemistry with crustal thickness and lunar sample chemistry

A correlation between orbital chemistry (FeO, Al2O3, Mg/Al, MgO/FeO, Th) and the lunar crustal thickness is examined. The correlation suggests either lack of complete homogenization by lateral or vertical mixing, or lateral variation in the differentiation process. In addition, links between orbital chemistry and lunar sample chemistry are investigated. In regions with crustal thickness between 100 and 110 km, gabbroic anorthosites are very abundant, while in regions with crustal thickness of about 80 km anorthositic gabbros are frequent. Special attention is given to the distribution of low-potassium Fra Mauro basalt, found in high concentrations in regions with 50 to 60 km crustal thickness.

Schonfeld, E.↗
NASA NTRS1975

Transport and emplacement of crater and basin deposits

Material is ejected from impact craters in ballastic trajectories; it impacts first near the crater rim and then at progressively greater ranges. Ejecta from craters smaller than approximately 1 km are laid predominantly on top of the surrounding surface. With increasing crater size, more and more surrounding surface will be penetrated by secondary cratering action, and these preexisting materials will be mixed with primary crater ejecta. Ejecta from large craters, and especially basin-forming events, not only excavate preexisting local materials, but also are capable of moving large amounts of material away from the crater. Thus mixing and lateral transport give rise to continuous deposits that contain materials from within and outside the primary crater. As a consequence, ejecta of basins and large highland craters have eroded and mixed highland materials throughout geologic time and deposited them in depressions inside and between older crater structures.

Oberbeck, V. R.↗
DOE OSTI2025

Observations of Subduction, Downward Heat Flux and Dense Filament Collapse in the Northern Gulf of Mexico

Submesoscale processes are important contributors to the global heat budget and generally support upward heat transport through restratification. However, in salinity‐stratified regions, such as the northern Gulf of Mexico with its influx of freshwater from the Mississippi‐Atchafalaya river system, temperature can act like a passive tracer and submesoscale processes can contribute to downward heat transport. Oceanic heat content is a factor in many environmental risks the region faces, for example, hurricane intensification, and marine heatwaves. During the 2022 field campaign of the Submesoscales Under Near‐Resonant Inertial Shear Experiment, a sampling plan was developed to study such submesoscale processes in high resolution. Over 31 hr, four assets (two research ships and two remotely controlled boats) drove in parallel across a dense filament, capturing its evolution in time and space. The observations show that surface waters, warmed by daytime solar radiation, were subducted and that the associated overturning circulation transported heat below the surface layer where it was later irreversibly mixed away. The estimated downward heat flux was as strong as the concurrent net air‐sea heat flux into the ocean. The filament was then observed to rapidly collapse which we attribute to boundary layer turbulence and the breakdown of geostrophic balance. The collapsing fronts display behaviors indicative of gravity currents. These observations highlight how in salinity‐stratified regions, frontal dynamics can be associated with downward heat flux and how the submesoscale can play an important role in the oceanic heat budget.

58 GEOSCIENCES↗
DOE OSTI2025

Extended Heat Transfer Model Dataset

Data repository for the paper: Molerus and Wirth's Heat Transfer Model for Bubbling Fluidized Beds: Proposal for an Extended Model Including Immersed Tube Banks and Particle Cross-Flow Powder Technology 2025

contact time↗
NASA NTRS1986

Variation of the urban NO2 concentration during a ground inversion situation

In February 1985 the NO2 concentration over Goeteborg, a major Swedish city, was monitored during two inversion situations. The differential absorption technique was employed and the results show the build-up of the concentration. In this experiment the laser beam was scanned horizontally over Goeteborg. The results were presented as maps over the NO2 concentration distribution. For security reasons the beam was not parallel to the ground, which gives a height gradient in some measurements. During the measurement period the NO2 concentration variation build-up from the morning to the afternoon was monitored. Great concentration variations were seen. Later the mixing below the inversion layer, resulting in a more uniform, high concentration was seen. The breakdown of the inversion when stronger winds start was also seen. Comparisons with a traditional point-measuring chemiluminiscence instrument and an optical method DOAS (Differential Optical Absorption Spectroscopy), were made. The results are discussed. Strong spatial concentration variations are shown by the lidar measurements. For a point-measuring system, the instrument must be very carefully placed since its location will strongly influence the values it gives.

Sunesson, A.↗
NASA NTRS1993

I-Xe structure of ILAFEGH 009 and shallowater: Evidence for early formation and rapid cooling of impact-derived enstatite meteorites

Enstatite meteorites have proven to be ideal samples for past studies of the I-Xe system. This work focuses on two enstatite meteorites that were formed by impact processes. Ilafegh 009 is a clast-free impact melt rock from the EL chondrite parent body. The Shallowater aubrite likely formed when a fully molten planetesimal collided with a solid planetesimal, mixing fragments of the solid planetesimal into the enstatite mantle of the molten planetesimal. A complex three-stage cooling history resulted from this mixing and later break-up and reassembly of the parent body. The present study indicates that the I-Xe structure of these two meteorites resulted from in situ decay of live I-129 and that both experienced xenon closure of the iodine host phase at approximately the same time. I-Xe cooling rates are consistent with the cooling rates derived from mineralogic and petrologic studies of these objects. The similarities in ages suggest that the region of the nebula in which enstatite parent bodies formed must have experienced an intense early bombardment.

Kehm, K.↗
NASA NTRS2004

Comparison of the Geologic Setting of the South Pole-Aitken Basin Interior with Apollo 16: Implications for Regolith Components

The interior of the South Pole-Aitken Basin (SPA) contains ancient cratered terrain that is possibly remnant of the original interior of the basin. This terrain has been modified by the addition of and mixing with foreign material introduced by later basins and craters of all sizes (lateral and vertical mixing). Since much of our thinking about ancient regolith is based on detailed analysis of samples from one nearside ancient heavily cratered highland site, Apollo 16 (Ap16), it is instructive to compare the interior of SPA with the Ap16 landing site. For this comparison we use a central location within SPA (SPA-1 at 60 deg. S, 160 deg. W). Two models have recently been presented that allow estimation of the amount of original SPA interior material likely to remain in the regolith of SPA. Although the details of each model are different, results consistently range from 50-82% original material in the regolith. The models also allow the contribution from individual basins to be predicted.

Petro, N. E.↗
NASA NTRS2002

Fundamental Mixing and Combustion Experiments for Propelled Hypersonic Flight

The first experiment is a study of a coaxial jet discharging into stagnant laboratory air, with center jet of a mixture of 5% oxygen and 95% helium by volume and coflow jet of air. The exit flow pressure of both center-jet and coflow nozzles is 1 atmosphere. The presence of oxygen in the center jet is to allow the use of an oxygen flow-tagging technique (RELIEF4) to obtain non-intrusive velocity measurements. Both jets are nominally Mach 1.8, but, because of the greater speed of sound, the center jet velocity is more than twice that of the coflow. The mixing layer which forms between the center jet and the coflow near the nozzle exit is compressible, with a calculated convective Mach number of approximately 0.7. This geometry has several advantages: The streamwise development of the flow is generally dominated by turbulent stresses (rather than pressure forces), and thus calculations are sensitive to turbulence modeling. It includes features present in supersonic combustors, including a compressible mixing layer near the nozzle exit and a light-gas/air plume downstream. Since it is a free jet, it provides easy access for both optical instrumentation and probes. Since it is axisymmetric, it requires fewer experimental measurements to fully characterize, and calculations can be performed with more modest computer resources. However, weak shock waves formed at the nozzle exit strengthen and turn normal as they approach the axis, complicating the flow. Care is thus taken in the design of the facility to provide as near as possible to 1-D flow at the exit of both center and coflow nozzles, and to minimize the strength of waves generated at the nozzle exit. Results from this experiment are compared to CFD solutions obtained by VULCAN, a previously developed code used in engine analysis. The second experiment is a study of a supersonic combustor consisting of a diverging duct with single downstream-angled wall injector. Thus, the geometry is relatively simple and large regions of subsonic recirculating flow are avoided. The nominal entrance Mach number is 2 and the enthalpy of the test gas (hot air "simulant") is nominally that of Mach 7 flight. It was believed, on the basis of calculations performed that this would produce mixing-limited flow, that is to say, one for which chemical reaction to equilibrium proceeds at a much greater rate than mixing. It later proved that this was not the case. The primary experimental technique employed is coherent anti-Stokes Raman spectroscopy, known by its acronym CARS. The species probed is molecular nitrogen and the quantity measured is temperature. Intrusive probes, such as Pitot, total temperature, hot-wire, etc., are not used due to access difficulty and high heat flux in the combustor, and because they may alter the flow. CARS has several advantages over other optical methods. It is a relatively mature and well-understood technique. Signal levels are relatively high and the signal is in the form of a coherent (laser) beam that can be collected through small windows. Incoherent (non-CARS) interferences are rejected by spatial filtering.

Diskin, G. S.↗
NASA NTRS2005

Evolution of a Florida Cirrus Anvil

This paper presents a detailed study of a single thunderstorm anvil cirrus cloud measured on 21 July 2002 near southern Florida during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers--Florida Area Cirrus Experiment (CRYSTAL-FACE). NASA WB-57F and University of North Dakota Citation aircraft tracked the microphysical and radiative development of the anvil for 3 h. Measurements showed that the cloud mass that was advected downwind from the thunderstorm was separated vertically into two layers: a cirrus anvil with cloud-top temperatures of -45?C lay below a second, thin tropopause cirrus (TTC) layer with the same horizontal dimensions as the anvil and temperatures near -70?C. In both cloud layers, ice crystals smaller than 50 ?m across dominated the size distributions and cloud radiative properties. In the anvil, ice crystals larger than 50 ?m aggregated and precipitated while small ice crystals increasingly dominated the size distributions; as a consequence, measured ice water contents and ice crystal effective radii decreased with time. Meanwhile, the anvil thinned vertically and maintained a stratification similar to its environment. Because effective radii were small, radiative heating and cooling were concentrated in layers approximately 100 m thick at the anvil top and base. A simple analysis suggests that the anvil cirrus spread laterally because mixing in these radiatively driven layers created horizontal pressure gradients between the cloud and its stratified environment. The TTC layer also spread but, unlike the anvil, did not dissipate--perhaps because the anvil shielded the TTC from terrestrial infrared heating. Calculations of top-of-troposphere radiative forcing above the anvil and TTC showed strong cooling that tapered as the anvil evolved.

Garrett, T. J.↗
NASA NTRS2009

Pulling Marbles from a Bag: Deducing the Regional Impact History of the SPA Basin from Impact Melt Rocks

The South Pole-Aitken (SPA) basin is an important target for absolute age-dating. Vertical and lateral impact mixing ensures that regolith within SPA will contain rock fragments from SPA itself, local impact craters, and faraway giant basins. About 20% of the regolith at any given site is foreign [1, 2], but much of this material will be cold ejecta, not impact melt. We calculated the fraction of contributed impact melt using scaling laws to estimate the amount and provenance of impact melt, demonstrating that SPA melt is the dominant impact melt rock (>70%) likely to be present. We also constructed a statistical model to illustrate how many randomly-selected impact-melt fragments would need to be dated, and with what accuracy, to confidently reproduce the impact history of a site. A detailed impact history becomes recognizable after a few hundred to a thousand randomly-selected marbles, however, it will be useful to have more information (e.g. compositional, mineralogical, remote sensing) to group fragments. These exercises show that SPA melt has a high probability of being present in a scoop sample and that dating of a few hundred to a thousand impact-melt fragments will yield the impact history of the SPA basin.

Cohen, Barbara A.↗