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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Areal measurement of Mercury's first quadrant

Various linear and areal measurements of Mercury's first quadrant which were used in geological map preparation, map analysis, and statistical surveys of crater densities are discussed. Accuracy of each method rests on the determination of the scale of the photograph, i.e., the conversion factor between distances on the planet (in km) and distances on the photograph (in cm). Measurement errors arise due to uncertainty in Mercury's radius, poor resolution, poor coverage, high Sun angle illumination in the limb regions, planetary curvature, limited precision in measuring instruments, and inaccuracies in the printed map scales. Estimates are given for these errors.

Leake, M. A.↗
NASA NTRS2019

Analysis of Mercury Laser Altimeter Crossovers with Improved Mercury and MESSENGER Ephemerides

Based on previous applications of laser altimetry to planetary geodesy at GSFC [Mazarico et al. (2014),(2016)] and taking advantage of new accurate Mercury and MESSENGER orbits by [Genova et al. (2019)], we analyze altimetric crossovers from the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) Laser Altimeter (MLA) to solve for orbital and geodetic parameters (e.g., rotation and orientation). We present our results based on a new Python software package recently developed at GSFC that can simulate and process altimetry data in a closed-loop. Realistic simulations of MLA data, including an appropriate range noise from the instrument and realistic terrain roughness, are performed in order to fully characterize the robustness of the solution. The simulation results are then applied to our analysis of the full dataset acquired by the MLA instrument.

Bertone, Stefano↗
DOE OSTI2024

Uptake, Efflux, and Sequestration of Mercury in the Asian Clam, Corbicula fluminea , at Environmentally Relevant Concentrations, and the Implications for Mercury Remediation

(1) Mercury (Hg) is a persistent, ubiquitous contaminant that readily biomagnifies into higher trophic level species in aquatic environments across the globe. It is crucial to understand the movement of environmentally relevant concentrations of Hg in impacted freshwater streams to minimize risks to ecological and human health. (2) The bioconcentration kinetics of aqueous Hg exposure (20, 100, and 200 ng/L) in the invasive Asian Clam, Corbicula fluminea, were measured. A toxicokinetic model, the first parameterized for Hg accumulation in freshwater clams, was developed to estimate uptake and efflux parameters and compared to previous parameter values estimated for other mollusk species. (3) Results demonstrated that even at low Hg concentrations, Corbicula record signals of contamination through bioconcentration, and both direct measurement and toxicokinetic models demonstrate large Hg bioconcentration factors (as high as 1.34 × 10 5 mL/g dry tissue), similar to partitioning coefficients seen in engineered Hg sorbents. (4) Our study found that Corbicula accumulated Hg at aqueous concentrations relevant to impacted streams, but well below regulatory drinking water limits, demonstrating their utility as a sensitive sentinel species and potential bioremediator.

bioaccumulation↗
NASA NTRS1973

Ion time-of-flight determinations of doubly to singly ionized mercury ion ratios from a mercury electron bombardment discharge

Doubly to singly charged mercury ion ratios in electron bombardment ion thruster exhaust beams have been determined as functions of bombardment discharge potential, thrust beam current, thrust beam radial position, acceleration-deceleration voltage ratio, and propellant utilization fraction. A mathematical model for two-step ionization processes has been derived, and calculated ion ratios are compared to observed ratios. Production of Hg(++) appears to result primarily from sequential ionization of Hg(+) in the discharge. Experimental and analytical results are presented, and design, construction, and operation features of an electrostatic deflection ion time-of-flight analyzer for the determination of the above-mentioned ratios are reviewed.

Sellen, J. M., Jr.↗
NASA NTRS1975

Mariner Venus-Mercury 1973 project. Volume 2: Extended mission-Mercury 2 and 3 encounters

The Mariner Venus/Mercury 1973 mission operations Extended Mission is described. The activities are summarized from shortly after Mercury I through the end of mission. The operational activities are reported by Mission Operations Systems functions providing a brief summary from each discipline. Based on these experiences recommendations for future projects are made.

Source record↗
NASA NTRS1976

Mariner Venus-Mercury 1973 Project. Volume 1: Venus and Mercury 1 Encounters

The primary mission report includes the Venus encounter and the first Mercury encounter. Plans and activities undertaken to successfully achieve the mission objectives are described. Operational activities are identified by mission operation system functions, providing a brief summary of each discipline. Spacecraft performance is summarized by subsystems.

Source record↗
NASA NTRS1982

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal histories of Mercury and the Moon

To determine a planet's thermal history, a wide range of data is necessary. These data include remote sensing results, photogeologic evidence, magnetic field and remanent magnetization data, composition and ages of samples, and physical parameters of the planet and its orbit. Few of these data form unambiguous constraints for thermal models of Mercury. Igneous Chronology as the time history of the differentiation and igneous activity, is defined. Igneous Chronology is used here in the sense of the apparent igneous or relative chronology of geologic events, such as plains formation (through whatever mechanism) relative to the crater production and tectonic history (lineament and scarp formation).

Leake, M. A.↗
NASA NTRS1982

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Discussion of the nature, origin and role of the intercrater plains of Mercury and the Moon

The nature and origin of the intercrater plains of Mercury and the Moon as determined through geologic mapping, crater statistics, and remotely sensed data are summarized. Implications of these results regarding scarp formation, absolute ages, and terrestrial planet surfaces are included. The role of the intercrater plains is defined and future work which might lead to a better understanding of these units and terrestrial planet evolution is outlined.

Leake, M. A.↗
NASA NTRS1982

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal models of Mercury

Recent and more complex thermal models of Mercury and the terrestrial planets are discussed or noted. These models isolate a particular aspect of the planet's thermal history in an attempt to understand that parameter. Among these topics are thermal conductivity, convection, radiogenic sources of heat, other heat sources, and the problem of the molten core and regenerative dynamo.

Leake, M. A.↗
NASA NTRS1982

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Chronology of surface history of Mercury

Phases in the history of the planet Mercury include: (1) condensation and accretion; (2) heating; (3) planetary expansion during heavy bombardment; (4) tidal spin-down and lineament formation; (5) P5 plains emplacement; (6) P4 plains emplacement; (7) peak planetary volume in P3 period; (8) scarp formation; (9) Caloris Basin formation, late class 3; (10) scarp formation and P2 plains formation; (11) smooth plains formation in and around large basins; (12) late or local tectonic stress; and (13) quiescent class 1 period. Although the cooling and contraction of the lithosphere are complete, the core remains molten as an active dynamo, producing the magnetic fields detected by Mariner 10. Plains produced since core formation (P3 to P-1) should record its magnetic activity. Cratering during the Class 2 and Class 1 periods is probably not enough to distribute ballistic materials and homogenize any color differences.

Leake, M. A.↗
NASA NTRS1970

20th Century NASA History: Mercury Manned Orbital Capsule Detail Specification and Project Mercury Capsule Flight Operations Manual

The detailed preparation required in attempting a mission of the magnitude and scope of PROJECT MERCURY obviously cannot and need not be covered in a document of the handbook type. Prior to any actual attempt to launch a manned capsule, many weeks will be spent in an extensive training and familiarization program. The information contained in this manual, therefore, will pre-suppose a detailed knowledge of the capsule systems and will be confined, for the most part, to procedural data.

Source record↗
NASA NTRS1973

Electrostatic Propulsion Beam Divergence Effects on Spacecraft Surfaces. Volume 2, Addendum 1: Ion Time-of-flight Determinations of Doubly to Singly Ionized Mercury Ion Ratios from a Mercury Electron Bombardment Discharge

The analysis of ion exhaust beam current flow for multiply charged ion species and the application to propellant utilization for the thruster are discussed. The ion engine in use in the experiments is a twenty centimeter diameter electromagnet electron bombardment engine. The experimental technique to determine the multiply charged ion abundance ratios using ion time of flight is described. An analytical treatment of the discharge action in producing various ion species has been carried out.

Sellen, J. M., Jr.↗