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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 91 records · Page 5

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NASA NTRS1975

Ancient meteoritic component in Apollo 17 boulders

The reported investigation is concerned with the resolution of a number of questions related to the ancient meteoritic component in Apollo 17 boulders. Numerical taxonomic methods have been adopted to objectively group the components. Only the nonvolatile siderophile elements have been used for the classification. Efforts were made to obtain data on the metal composition of breccias analyzed for trace elements, to determine if metal homogeneity was reflected in siderophile ratios. Thirty-one samples were analyzed of which twenty-eight have significant siderophile contents. It is concluded that highland breccias are largely the product of large basin-forming impacts. Highland soils are then produced by comminution of the breccias by small local impacts and micrometeorite bombardment. The long-lived component of bulk soils considered by Baedecker et al. (1974) is thought to contain a substantial micrometeorite contribution, plus assorted debris.

Higuchi, H.↗

NASA NTRS1977

Solar energetic particles below 10 MeV

The information on solar acceleration and coronal propagation contained in low energy solar particle observations must be extracted from the effects of propagation in a dynamic interplanetary medium and the proximity of the earth's magnetosphere. The resulting separation reveals long-lived coronal injection and strong spatial ordering of coronal propagation.

Roelof, E. C.↗

NASA NTRS1976

OAST Space Theme Workshop. Volume 2: Theme summary. 1: Space power (no. 7). A. Theme statement. B. 26 April 1976 presentation. C. Summary. D. Initiative action

A long-lived space-based system that converts on-orbit solar and/or nuclear energy to a suitable form for distribution to using space systems is described. Mission applications, requirements, issues, problems, benefits, and technology thrusts are identified for the multipurpose power platform. Power levels of at least 10-100Kw are required for space manufacturing, satellites, and space station operations. Two Mw are needed for a proposed passive radar system. Propulsion system requirements are in the 100Kw-100Mw range.

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NASA NTRS1979

Association of corotating magnetic sector structure with Jupiters decameter-wave radio emissions

Chree (superposed epoch) analyses of Jupiter's decameter-wave radio emission taken from the new Thieman (1979) catalog show highly significant correlation with solar activity indicated by the geomagnetic Ap index. The correlation effects can be explained in terms of corotating interplanetary magnetic sector features. At times when the solar wind velocity is relatively low, about 300 to 350 km/s, a sector boundary can encounter the Earth and Jupiter almost simultaneously during the period immediately before opposition. After opposition this will not normally occur as the solar wind velocities necessary are too low. The correlation effects are much enhanced for the three apparitions of 1962-1964 during which a relatively stable and long-lived sector pattern was present. Chree analyses for this period indicate periodicities, approximately equal to half the solar rotation period, in the Jupiter data.

Barrow, C. H.↗

NASA NTRS1979

Titanium-alloy, metallic-fluid heat pipes for space service

Reactivities of titanium limit its long-term terrestrial use for unprotected heat-pipe envelopes to about 870 K (1100 F). But this external thermochemical limitation disappears when considerations shift to space applications. In such hard-vacuum utilization much higher operating temperatures are possible. Primary restrictions in space environment result from vaporization, thermal creep, and internal compatibilities. Unfortunately, a respected head-pipe reference indicates that titanium is compatible only with cesium from the alkali-metal working-fluid family. This problem and others are subjects of the present paper which advocates titanium-alloy, metallic-fluid heat pipes for long-lived, weight-effective space service between 500 and 1300 K (440 and 1880 F).

Morris, J. F.↗

NASA NTRS1979

Gas core reactors for actinide transmutation

The preliminary design of a uranium hexafluoride actinide transmutation reactor to convert long-lived actinide wastes to shorter-lived fission product wastes was analyzed. It is shown that externally moderated gas core reactors are ideal radiators. They provide an abundant supply of thermal neutrons and are insensitive to composition changes in the blanket. For the present reactor, an initial load of 6 metric tons of actinides is loaded. This is equivalent to the quantity produced by 300 LWR-years of operation. At the beginning, the core produces 2000 MWt while the blanket generates only 239 MWt. After four years of irradiation, the actinide mass is reduced to 3.9 metric tonnes. During this time, the blanket is becoming more fissile and its power rapidly approaches 1600 MWt. At the end of four years, continuous refueling of actinides is carried out and the actinide mass is held constant. Equilibrium is essentially achieved at the end of eight years. At equilibrium, the core is producing 1400 MWt and the blanket 1600 MWt. At this power level, the actinide destruction rate is equal to the production rate from 32 LWRs.

Clement, J. D.↗

NASA NTRS1979

Space augmentation of military high-level waste disposal

Space disposal of selected components of military high-level waste (HLW) is considered. This disposal option offers the promise of eliminating the long-lived radionuclides in military HLW from the earth. A space mission which meets the dual requirements of long-term orbital stability and a maximum of one space shuttle launch per week over a period of 20-40 years, is a heliocentric orbit about halfway between the orbits of earth and Venus. Space disposal of high-level radioactive waste is characterized by long-term predictability and short-term uncertainties which must be reduced to acceptably low levels. For example, failure of either the Orbit Transfer Vehicle after leaving low earth orbit, or the storable propellant stage failure at perihelion would leave the nuclear waste package in an unplanned and potentially unstable orbit. Since potential earth reencounter and subsequent burn-up in the earth's atmosphere is unacceptable, a deep space rendezvous, docking, and retrieval capability must be developed.

English, T.↗

NASA NTRS1978

The radial variation of corotating energetic particle streams in the inner and outer solar system

Spacecraft observations of 0.9 to 2.2 MeV protons are used to evaluate the radial gradient of long-lived corotating energetic particle streams for several time periods from mid-1973 to mid-1976. New evidence is presented for a positive gradient between 0.3 and some 3-4 AU and a negative one beyond some 3-5 AU. The relation between the corotating events in the inner solar system and the accompanying interplanetary magnetic field and solar wind is examined. It is shown, independently of possible secondary latitudinal effects, that between 0.3 and 1 AU, in a region where gradients up to 300%/AU exist, the particle stream is propagating inside a fast solar wind stream in a region adjacent to low- and high-speed stream interactions.

Van Hollebeke, M. A. I.↗

NASA NTRS1978

Crossed beam studies of O/-/ + D2 yields OD/-/ + D

Using the crossed-beam machine EVA measurements have been conducted of the product angular and energy distributions of the reaction O(-) + D2 yields OD(-) + D in the relative energy range of 1.2-4.7 eV (5.7-23.1 eV LAB). Below 2.5 eV the product distribution is centered about the center of mass, indicating a long-lived complex. Above 2.5 eV the distribution slowly moves forward. Most of the available energy goes into internal energy of the products.

Johnson, S. G.↗

NASA NTRS1978

Coronal holes, solar wind streams, and geomagnetic activity during the new sunspot cycle

The paper presents results obtained for 1976-1977 using daily He I 10830 A spectroheliograms and photospheric magnetograms. It was found that as the magnetic field patterns changed, the solar atmosphere evolved from a structure with a few large long-lived low-latitude coronal holes to one with numerous small short-lived high-latitude holes. High-latitude holes recurred with a synodic rotation period of 28-29 days instead of the 27-day period already known to be characteristic of low-latitude holes. A Bartels display of the occurrence of holes, wind speed, and geomagnetic activity is considered.

Sheeley, N. R., Jr.↗

NASA NTRS1978

The relationship between solar activity and coronal hole evolution

The relationship between coronal hole evolution and solar active regions during the Skylab period is examined. A tendency is found for holes to grow or remain stable when the activity nearby, seen as calcium plages and bright regions in X-rays, is predominantly large, long-lived regions. It is also found that there is a significantly higher number of small, short-lived active regions, as indicated by X-ray bright points, in the vicinity of decaying holes than there is near other holes. This is interpreted to mean that holes disappear at least in part because they become filled with many small scale, magnetically closed, X-ray emitting features. This interpretation, together with the observation that the number of X-ray bright points was much larger near solar minimum than it was during the Skylab period, provides a possible explanation for the disappearance of the large, near-equatorial coronal holes at the time of solar minimum.

Nolte, J. T.↗

NASA NTRS1979

Six collapses

The self-consistent dynamical development of six stellar systems, started from rotating spherical configurations, has been studied by means of a fully three-dimensional n-body integration. The six examples had different initial angular velocities and velocity dispersions. All settled down into prolate bars rotating about a short axis within two initial rotation periods. The bars are long-lived, robust, and stable. Bars are the natural form toward which rapidly rotating stellar dynamical systems develop, instead of the flattened axisymmetric disks that had been expected. The early stages of each collapse are reasonably well described by a theoretical model according to which a collapse passes through a sequence of rigidly rotating, uniform-density spheroids. The first significant departures from spheroidal form were axisymmetric in all cases. Rings formed in some examples, sheets in others, with transition cases between these extremes. Nonaxisymmetric forms developed from these intermediate stages.

Miller, R. H.↗

NASA NTRS1979

A correlation

The paper reports on some correlative features of two sets of space-based atmospheric measurements which are globally distributed with good statistical coverage. One set of data, pertaining to tropospheric processes, is lightning occurrence frequency derived from measurements aboard the DMSP satellite. The second set of data, pertaining to thermospheric processes, is the occurrence frequency of wavelike structures in neutral atmospheric density profiles derived from measurements aboard AE-C and AE-D. A significant correlation was found between the occurrence patterns of dawn lightning, which is indicative of massive long-lived tropospheric convective activity, and the occurrence patterns of wavelike structures in the thermosphere.

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NASA NTRS1979

Characteristics of the spectra of protons and alpha particles in recurrent events at 1 AU

A study of 31 individual recurrent events from three long-lived corotating particle streams is presented. The spectra of protons and alpha particles during these streams are fit well by an exponential in particle rigidity. Although the spectra show considerable temporal variation, the proton and alpha particle spectra are correlated so that the e-folding rigidities Po(alpha) and Po(p) of the two spectra are in the ratio Po(alpha)/Po(p) = 1.5 plus or minus 0.1. The consistency of this ratio may be a characteristic of the interplanetary acceleration process.

Mewaldt, R. A.↗

NASA NTRS1979

Nuclear gamma-rays from energetic particle interactions

Gamma-ray line emission due to nuclear deexcitation following energetic particle interactions with abundant constituents of cosmic matter is studied. Reactions induced by energetic protons and alpha particles in ambient nuclei (He, C, N, O, Ne, Mg, Al, Si, S, Ca, and Fe) are considered, along with inverse reactions in which energetic nuclei interact with ambient H and He. Line-production cross sections are evaluated by analyzing a large body of laboratory nuclear data. Both prompt gamma rays, produced by direct excitation of nuclear levels and by spallation reactions that leave the secondary nucleus in an excited state, and delayed emission from long-lived radioactive nuclei also produced in the energetic particle reactions are investigated. A line list is provided, and the shapes of the gamma-ray lines are determined. Gamma-ray line production in the interstellar medium is evaluated in detail.

Ramaty, R.↗

NASA NTRS1980

Core formation, evolution, and convection - A geophysical model

A model for the formation and evolution of the earth's core, which provides an adequate energy source for maintaining the geodynamo, is proposed. A modified inhomogeneous accretion model is proposed which leads to initial iron and refractory enrichment at the center of the planet. The probable heat source for melting of the core is the decay of Al-26. The refractory material is emplaced irregularly in the lowermost mantle with uranium and thorium serving as a long-lived heat source. Fluid motions in the core are driven by the differential heating from above and the resulting cyclonic motions may be the source of the geodynamo.

Ruff, L.↗

NASA NTRS1980

A study of the Jovian forbidden line S II nebula at high spectral resolution

Observations of forbidden line S II 6716-6731 A emissions from the Jovian magnetosphere have been carried out with a PEPSIOS spectrometer at the Hale 5 m telescope. Spectral resolving power was sufficient to resolve the forbidden line S II line widths. From measured 6716-6731 A doublet ratios and spectral line widths a thermal plasma is found characterized by temperatures about 2 x 10 to the 4th K and electron densities about 2000 cu cm. The source of forbidden line S II emissions was centered within a toroidal region of radius 5 Jupiter radii (inside the orbit of Io), with tight latitudinal confinement near the equilibrium equator for ions in the tilted corotating Jovian magnetic field, and significant long-lived longitudinal structure.

Trauger, J. T.↗

NASA NTRS1980

IUE spectra of a flare in the RS Canum Venaticorum-type system UX Arietis

IUE spectra of UX Ari obtained during the large flare of 1979 January 1 exhibit chromospheric and transition-region emission-line fluxes about 2.5 and 5.5 times brighter than quiescent fluxes, respectively, and up to 1400 times brighter than the quiet sun. A high-dispersion spectrum of the 2000-3000 A region exhibits enhanced Fe II emission, which is probably associated mainly with the K0 IV star, and enhanced Mg II emission with asymmetric wings extending to +475 km/s. These line wings are interpreted as evidence for mass flow from the K0 IV star to the G5 V star. A speculative scenario of major long-lived RS CVn flares is proposed in which the component stars have very large corotating flux tubes, which occasionally interact. Magnetic reconnection results in flux tubes that temporarily connect the two stars.

Simon, T.↗