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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Data and scripts associated with “Allometric scaling of hyporheic respiration across basins in the Pacific Northwest USA"

This data package is associated with the publication “Allometric scaling of hyporheic respiration across basins in the Pacific Northwest USA” submitted to JGR-Biogeosciences (Regier et al. 2025).This study used reach-scale modeled estimates of hyporheic aerobic respiration made by the River Corridor Model (Fang et al. 2020) and watershed characteristics across the Willamette and Yakima River basins to explore potential allometric scaling (i.e., power-law relationships between size and function) of cumulative hyporheic respiration across catchment-to-basin scales. Scaling was explored quantitatively via the R2, slope, and y-intercept of relationships between cumulative hyporheic respiration and watershed area, divided into hyporheic exchange flux (HEF) quantiles. We also explored relationships between allometric scaling and other watershed characteristics through linear regression, spatial patterns, and mutual information analyses. Our results also suggest variability of hyporheic respiration allometry for middle exchange flux quantiles, and in relation to land-cover. Our findings provide initial evidence that allometric scaling may be useful for predicting hyporheic biogeochemical dynamics across watersheds from reach to basin scales. This data package is associated with the GitHub repository found at https://github.com/peterregier/rc_wrb_yrb_scaling. The data package is organized into several key directories. The “data” folder contains multiple CSV files, including landscape heterogeneity, scaling analysis, and watershed boundary data. The “figures” folder has all figure files in both PDF and PNG formats. Core analysis scripts and figure generation scripts are in the “scripts” directory, systematically numbered for sequential execution. The root directory includes essential project files; please see the file ending in “flmd.csv” for a list and description of all files contained in this data package and the file ending in “dd.csv” for data dictionaries used to describe tabular column headers.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

A semi-analytic study of self-interacting dark-matter haloes with baryons

ABSTRACT We combine the isothermal Jeans model and the model of adiabatic halo contraction into a semi-analytic procedure for computing the density profile of self-interacting dark-matter (SIDM) haloes with the gravitational influence from the inhabitant galaxies. The model agrees well with cosmological SIDM simulations over the entire core-forming stage up to the onset of gravothermal core-collapse. Using this model, we show that the halo response to baryons is more diverse in SIDM than in CDM and depends sensitively on galaxy size, a desirable feature in the context of the structural diversity of bright dwarfs. The fast speed of the method facilitates analyses that would be challenging for numerical simulations – notably, we quantify the SIDM halo response as functions of the baryonic properties, on a fine mesh grid spanned by the baryon-to-total-mass ratio, Mb/Mvir, and galaxy compactness, r1/2/Rvir; we show with high statistical precision that for typical Milky-Way-like systems, the SIDM profiles are similar to their CDM counterparts; and we delineate the regime of core-collapse in the Mb/Mvir − r1/2/Rvir space, for a given cross section and concentration. Finally, we compare the isothermal Jeans model with the more sophisticated gravothermal fluid model, and show that the former yields faster core formation and agrees better with cosmological simulations. We attribute the difference to whether the target CDM halo is used as a boundary condition or as the initial condition for the gravothermal evolution, and thus comment on possible improvements of the fluid model. We have made our model publicly available at https://github.com/JiangFangzhou/SIDM.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Fracture Shearing in the Eau Claire Formation

This data set consists of Computed Tomographic (CT) data for five sheared Eau Claire Formation core samples with complex and heterogeneous lithology. Each sample was prefractured, housed in a specially adapted core holder, and sheared in incremental fashion. CT scans were taken before and after each shearing event.

Computed Tomography↗
DOE OSTI2024

SPRUCE 13C-Phospholipid Fatty Acid (13C-PLFA) Abundances, June 2014-June 2015

This data set provides the results of 13C phospholipid fatty acid analysis (13C-PLFA) of peat samples collected from ambient and experimental plots in the SPRUCE experiment site. The samples used to generate this data set were collected just prior to initiation of deep peat heating (DPH; 03 June 2014), after 3 months (09 September 2014), and after 10 months (16 June 2015). This data set includes the abundances and delta-13C isotopic signatures of individual lipids and of groups of lipids indicating total biomass, fungi, Gram-positive bacteria, Gram-negative bacteria, actinomycetes, and anaerobic bacteria. This dataset contains two files in comma separate (*.csv) format. Cores extending to 250 cm (200 cm in June 2015) were collected and subsampled at 10 cm intervals from 0 and 100 cm and 25 cm intervals below 100 cm depth. During the lipid extraction procedure, samples were pooled into the following depth increments in order to obtain sufficient material to achieve adequate lipid yield: 0-20, 20-50, 50-100, 100-150, 150-200, and 200-250cm.

actinomycetes↗
NASA NTRS1976

Thermal expansion and thermal stress in the moon and terrestrial planets - Clues to early thermal history

The paper discusses how features of the surface geology of the moon and also Mars and Mercury impose constraints on the volumetric expansion or contraction of a planet and consequently provide a test of thermal history models. The moon has changed very little in volume over the last 3.8 b.y. Thermal models satisfying this constraint involve early heating and perhaps melting of the outer 200 km of the moon and an initially cold interior. Mercury has contracted by about 2 km in radius since emplacement of its present surface, so core formation must predate that surface. A hot initial temperature distribution is implied.

Solomon, S. C.↗
NASA NTRS1977

Origin and relative age of lunar and Mercurian intercrater plains

Differences in the diameter/density distribution of craters in the size range 7-100 km between heavily cratered areas and areas of intercrater plains indicate the deposition of both lunar and Mercurian intercrater plains has preferentially obliterated craters not greater than about 30 km diameter. This obliteration has altered the original lunar population distribution function from about a -1.3 slope to about -0.7 slope. At least a significant portion of both the lunar and Mercurian intercrater plains appear to be volcanic deposits emplaced during the later stages of heavy bombardment on each body rather than basin ejecta or an ancient primordial surface. The very widespread distribution of intercrater plains on Mercury compared to the moon may be related to Mercury's core formation which would have resulted in a large radius increase leading to widespread extensional fracturing to provide egress for the eruption of volcanic deposits on a global scale. This was followed by a radius decrease due to contraction of the lithosphere to produce thrust faulting represented by Mercury's lobate scarps.

Strom, R. G.↗
NASA NTRS1978

Thermal history and evolution of Mars

A thermal history of Mars is developed on the basis of available geophysical and geological data, including information obtained by the Viking missions. Specification of initial temperatures, composition and heat sources takes into account conduction and subsolidus mantle convection. Four phases in the Martian thermal history are distinguished. Core formation and crust differentiation occur during the first billion years. Partial melting, differentiation and outgassing of the mantle have taken place by the end of 3 billion years. In the 3- to 4-billion year epoch, the lithosphere thickens and the partial melt zone becomes deeper. By 4.6 billion years after commencement of evolution, volcanic activity has subsided, while the partial melt zone continues to shrink.

Toksoz, M. N.↗
NASA NTRS1977

Thermal evolution of planetary size bodies

The size dependence of planetary thermal evolution is investigated through calculations which take into account the effects of heat source differentiation and convection. The theoretical computations make use of hypothetical bodies for minor planets; Mercury, Venus and Mars are employed to represent the size spectrum of the inner planets. If started at a cold initial condition, an object with a radius less than 1000 km is unlikely to reach melting. Accretional heating, inductive heating and short half-life radioactive heating are among the mechanisms which may produce early melting and differentiation in larger planets. Core formation in Mercury and Venus is also discussed.

Hsui, A. T.↗
NASA NTRS1979

Past obliquity oscillations of Mars - The role of the Tharsis uplift

The paper deals with possible ancient variations of the obliquity of Mars. Consideration of data on internal differentiation, Tharsis uplift and crustal phenomena, mantle convection, and eigenfrequencies and mean motion suggest that (1) differentiation with core formation decreased the primeval spin precession constant (alpha) by 4-5%, driving it through resonance with the j = 2 orbital term; (2) a combination of geophysical processes caused alpha to drift back and forth through resonance with the j = 2 orbital term during part of Mars' history; (3) this situation was turned off by the Tharsis uplift, which drove alpha away from j = 2 resonance and possibly through the j = 26 resonance. The consequences of such events for the planet's obliquity are analyzed. Various types of motions are calculated, demonstrating the sensitivity of the obliquity to passage through resonance with such minor orbital terms.

Ward, W. R.↗
NASA NTRS1981

Orbital stability constraints on the nature of planetary systems

A fully self-consistent, N-body computer code is used to study conditions under which model planetary systems, each consisting of a star and two 'planetary' companions, become orbitally unstable as a result of gravitational interactions between the companions. A formula describing a necessary condition for orbital stability is given. It is found that giant gaseous protoplanets of the type postulated by Cameron (1978) to be precursors of the present-day solar system planets could have stable orbits for at least 10,000 years, the time required for significant core formation in a typical giant gaseous protoplanet.

Graziani, F.↗
NASA NTRS1984

Compositional trends and cooling rates of group IVB iron meteorites

It is found, on the basis of new neutron activation data for group IVB, that log-element - log-Ni trends are best understood in terms of core formation and fractional crytstallizaion. The limited compositional range found in gorup IVB is thought to reflect the fact that, owing to the low concentrations of S, P, and C and the high concentration of Ni, the k sub x (the solid/liquid partition ratio) values are closer to unity than are those in other magmatic groups. Mean volatile abundances in group IVB are significantly lower than those found in any group of chondritic meteorites, indicating that these low abundances are not entirely the result of nebular processes and that planetary outgassing was also involved.

Rasmussen, K. L.↗
NASA NTRS1985

Workshop on the Early Earth: The Interval from Accretion to the Older Archean

Presentation abstracts are compiled which address various issues in Earth developmental processes in the first one hundred million years. The session topics included: accretion of the Earth (processes accompanying immediately following the accretion, including core formation); impact records and other information from planets and the Moon relevant to early Earth history; isotopic patterns of the oldest rocks; and igneous, sedimentary, and metamorphic petrology of the oldest rocks.

Burke, K.↗
NASA NTRS1985

A review of noble gas geochemistry in relation to early Earth history

One of the most fundamental noble gas constraints on early Earth history is derived from isotopic differences in (129)Xe/(130)Xe between various terrestrial materials. The short half life (17 m.y.) of extinct (129I, parent of (129)Xe, means that these differences must have been produced within the first 100 m.y. after terrestrial accretion. The identification of large anomalies in (129)Xe/(130)Xe in mid ocean ridge basalts (MORB), with respect to atmospheric xenon, suggests that the atmosphere and upper mantle have remained separate since that time. This alone is a very strong argument for early catastrophic degassing, which would be consistent with an early fractionation resulting in core formation. However, noble gas isotopic systematics of oceanic basalts show that the mantle cannot necessarily be regarded as a homogeneous system, since there are significant variations in (3)He/(4)He, (40)Ar/(36)Ar, and (129)Xe/(130)Xe. Therefore, the early degassing cannot be considered to have acted on the whole mantle. The specific mechanisms of degassing, in particular the thickness and growth of the early crust, is an important variable in understanding present day noble gas inventories. Another constraint can be obtained from rocks that are thought to be derived from near the lithosphere asthenosphere boundary: ultramafic xenoliths.

Kurz, M. D.↗
NASA NTRS1984

Thermal evolution of Venus

A modification of the Boussinesq fluid assumption is the basis of the present theory of three-dimensional and finite amplitude convection in a viscous spherical shell with temperature- and pressure-dependent physical parameters. The theory is applied to the definition of thermal evolution models for Venus which emphasize the effects of certain physical parameters on thermal evolution, rather than the specific thermal history of the planet. It is suggested that a significant portion of the present temperature in the mantle and surface heat flux of Venus is due to the decay of a high temperature that was established in the planet at the completion of its core formation, and that Venus has been highly convective over the course of its history, until about 0.5 Ga ago.

Arkani-Hamed, J.↗
NASA NTRS1987

Meteoritic basalts: The nakhlites, their parental magmas, cooling rates, and equivalents on Earth

Proposed one-bar phase equilibrium experiments, designed to determine the compositions of the nakhlites' parental magmas, are in progress. Proposed field studies on Earth, designed to find occurrences of rocks like the nakhlites, were extraordinarily successful. Other work supported in the past year included: attendance at the 1986 national meeting of the Geological Society of America; attendance at the 18th Lunar and Planetary Science Conference; completion and publication of a study of core formation in the SNC parent body; initiation of a study of the flux of SNC meteorites onto the Earth; and initiation of petrologic study of the Angra dos Reis achondrite.

Treiman, Allan H.↗
NASA NTRS1987

Thermal evolution of a differentiated Ganymede and implications for surface features

Thermodynamic models are developed for the processes which controlled the evolution of the surface Ganymede, an icy Jovian satellite assumed to have a rock-rich core surrounded by a water-ice mantle. Account is taken of a heat pulse which would have arisen from a Rayleigh-Taylor instability at a deep-seated liquid-solid water interface, rapid fracturing from global stresses imposed by warm ice diapiric upwelling, impacts by large meteorites, and resurfacing by ice flows (rather than core formation). Comparisons are made with existing models for the evolution of Callisto, and the difficulties in defining a mechanism which produced the groove terrain of Ganymede are discussed.

Kirk, R. L.↗
NASA NTRS1988

Thermal models pertaining to continental growth

Thermal models are important to understanding continental growth as the genesis, stabilization, and possible recycling of continental crust are closely related to the tectonic processes of the earth which are driven primarily by heat. The thermal energy budget of the earth was slowly decreasing since core formation, and thus the energy driving the terrestrial tectonic engine was decreasing. This fundamental observation was used to develop a logic tree defining the options for continental growth throughout earth history.

Morgan, Paul↗