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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Use of remote sensing technology provided by the NASA/WFC Chesapeake Bay Ecological Program

Use of remote sensing technology provided through the NASA/Wallops Chesapeake Bay Ecological Program was investigated by means of extensive interviews with users. Since the inception of the Program four years ago, the technology has been used in 136 different managerial projects. Sixty-five regional managerial agencies took part in projects that the authors categorized as socioeconomic, political/managerial, monetary, legal, and other. Remote sensing technology was considered successful in 88.6 percent of the completed projects and unsuccessful in 2.8 percent.

Harman, D. M.↗
NASA NTRS1978

Quaternary geology of the Channeled Scabland and adjacent areas

The quaternary history of the channeled scabland is characterized by discrete episodes of catastrophic flooding and prolonged periods of loess accumulation and soil formation. The loess sequence was correlated with Richmond's Rocky Mountain glacial chronology. At least five major catastrophic flood events occurred in the general vicinity of the channeled scabland. The earliest episode occurred prior to the extensive deposition of the Palouse formation. The last major episode of flooding occurred between about 18,000 and 13,000 years ago. It probably consisted of two outbursts from glacial Lake Missoula.

Baker, V. R.↗
NASA NTRS1977

Endosymbionts and mitochondrial origins

The possibility is put forth that the mitochondrion did not originate from an endosymbiosis 1-2 billion years ago involving an aerobic bacterium. Rather, it arose by endosymbiosis in a much earlier anaerobic period and was initially a photosynthetic organelle analogous to the modern chloroplast. This suggestion arises from a reconsideration of the nature of endosymbiosis. It explains the remarkable diversity in mitochondrial information storage and processing systems.

Woese, C. R.↗
NASA NTRS1977

The origin of comets

Empirical data related to questions regarding the origin of comets are examined, taking into account the primitive temperature and its evolution, the cometary C-12/C-13 isotope ratio, the chemistry of comets, and the solar-system related orbits of the comets. The theories of cometary origin considered are related to a condensation of comets from the solar nebula and a later ejection into Oort's cloud, a recent condensation of comets in situ, a capture of interstellar comets, and a reversal of the arrow of time in the traditional evolution of comets. The only hypothesis which seems to survive an evaluation of the theories on the basis of the existing data is that the comets were condensed some five billion years ago in the vicinity of the giant planets or beyond, at the outer edge of the solar nebula.

Delsemme, A. H.↗
NASA NTRS1978

The evolution of the atmosphere of the earth

Computer simulations of the evolution of the earth's atmospheric composition and surface temperature have been carried out. The program took into account changes in the solar luminosity, variations in the earth's albedo, the greenhouse effect, variation in the biomass, and a variety of geochemical processes. Results indicate that prior to two billion years ago the earth had a partially reduced atmosphere, which included N2, CO2, reduced carbon compounds, some NH3, but no free H2. Surface temperatures were higher than now, due to a large greenhouse effect. When free O2 appeared the temperature fell sharply. Had earth been only slightly further from the sun, runaway glaciation would have occurred at that time. Simulations also indicate that a runaway greenhouse would have occurred early in earth's history had earth been only a few percent closer to the sun. It therefore appears that, taking into account the possibilities of either runaway glaciation or a runaway greenhouse effect, the continuously habitable zone about a solar-type star is rather narrow, extending only from roughly 0.95 to 1.01 AU.

Hart, M. H.↗
NASA NTRS1978

Imbrian-age highland volcanism on the moon - The Gruithuisen and Mairan domes

The Gruithuisen and Mairan domes on the moon represent morphologically and spectrally distinct nonmare extrusive volcanic features of Imbrian age. The composition, morphology, and age relationships of the domes indicate that nonmare extrusive volcanism in the northern Procellarum region of the moon continued until about 3.3 x 10 to the 9th to 3.6 x 10 to the 9th years ago and was partially contemporaneous with the emplacement of the main sequence of mare deposits.

Head, J. W., III↗
NASA NTRS1977

Origin of asteroids and the missing planet

Consideration is given to Ovenden's (1972) theory concerning the existence of a planet of 90 earth masses which existed from the beginning of the solar system and then disappeared 16 million years ago, leaving only asteroids. His model for secular perturbations is reviewed along with the principle of least interaction action (1972, 1973, 1975) on which the model is based. It is suggested that the structure of the asteroid belt and the origin of meteorites are associated with the vanished planet. A figure of 0.001 earth masses is proposed as a close estimate of the mass of the asteroidal belt. The hypothesis that the planet was removed through an explosion is discussed, noting the possible origin of asteroids in such a manner. Various effects of the explosion are postulated, including the direct impact of fragments on the earth, their impact on the sun and its decreased radiation, and the direct radiation of the explosion. A model for the disappearance of the planet by ejection in a gravitational encounter with a passing mass is also described.

Opik, E. J.↗
NASA NTRS1978

Scale covariant cosmology and the temperature of the earth

Geological data are used as cosmological determinants in a study of the temperature of the early earth (2.3 to 4.5 billion years ago). It is known that the energy output of the sun during that period was on the order of 30-40% lower than at present, and deduced that the mean temperature of the earth should have fallen to as low as 245 K, i.e., below the freezing point of seawater. Strong evidence exists, however, to indicate that algae (therefore liquid water) was present. To reconcile the discrepancies, a model is proposed whereby terrestrial G and M vary. It is further noted that atmosphere H2 may be a better agent than NH3 for producing a greenhouse effect.

Canuto, V.↗
NASA NTRS1978

Rb-Sr isochron age of the Manicouagan melt sheet, Quebec, Canada

Rb-Sr isotopic data for mineral separates from a rock of the Manicouagan impact melt sheet define an isochron of age T = 214 + or - 5 (2 sigma) m.y. which agrees with the K-Ar age of 210 + or - 8 (2 sigma) calculated by Wolfe (1971). The initial Sr-87/Sr-86 ratio I is found to be 0.70991 + or - 0.00007 (2 sigma); four whole rock samples yield age-corrected I values ranging from 0.70965 to 0.71006. These high I values support the hypothesis that the melt sheet was derived by total melting of Grenville basement rocks during the impact event 214 m.y. ago.

Jahn, B.↗
NASA NTRS1978

Martian cratering V - Toward an empirical Martian chronology, and its implications

This paper estimates ages of Martian features by dividing least-square-fitted crater densities by an estimated Martian crater production rate. This method is more rigorous than methods based purely on assumptions about correspondence of lunar and Martian cratering rates. Results are interpreted as supporting the conclusion of Burns et al (in press) that Mars shifted climatic states due to a change in obliguity caused by buildup of massive volcanics. Prior to a few gy. ago, conditions favored erosion, deposition, and fluvial channel formation. Recent volcanics postdate this era, and the surfaces of the major shields are fairly well constrained in age to a few hundred my, in agreement with Masursky et al.

Hartmann, W. K.↗
NASA NTRS1977

Geology of the Imbrium Basin Apennine Mountains and relation to the Apollo 15 landing site

Detailed mapping of the Imbrium Basin Apennine Mountains has emphasized several important factors in the geologic evolution of this region. Pre-Imbrian topography was composed of two types of landforms: (1) the nearby Serenitatis, South Imbrium, Aestuum, and Vaporum basins which produced widely spaced regional lows and a sequence of basin deposits; (2) pre-Imbrian craters that reworked existing basin deposits and produced local topographic lows. The sequence of events during the Imbrium impact can be summarized as follows: intensive structural uplift along the Apennine Front occurred prior to the emplacement of ballistic ejecta. Ejecta became more discontinuous toward the backslope and produced radial texture by sedimentary erosional and depositional processes. Post-ejecta-emplacement downfaulting exposed pre-Imbrian deposits along the front and caused severe seismic disturbances that reworked many of the previous units and accentuated pre-basin structures. Tectonic mapping and orbital geophysical data support the idea that little structural modification has occurred in the Apennines since their formation 3.9 b.y. ago.

Spudis, P.↗
NASA NTRS1977

Depositional history of the Apollo 16 deep drill core

Ferromagnetic resonance and magnetic hysteresis loop measurements were performed on 212 samples from the Apollo 16 deep drill core. The total iron content is generally uniform with a mean value of 5.7 plus or minus 0.9 wt%. The soils range in maturity from immature to mature. Two major contacts were observed. The contact at 13 cm depth represents a fossil surface whereas the contact at 190 cm depth has no time-stratigraphic significance. The data suggest that the core section below 13 cm depth was deposited in a single impact event and subjected to meteoritic gardening for about 450 m.y. However, our data do not preclude deposition by a series of closely spaced events. About 50 m.y. ago, the top 13 cm were added. Comparison with the Apollo 16 double drive tube 60009/60010 does not yield any evidence for a stratigraphic correlation with the deep drill core.

Gose, W. A.↗
NASA NTRS1975

Pb loss from Apollo 17 glassy samples and Apollo 16 revisited

U-Th-Pb analyses of bulk samples of soil breccia 70019, when compared to KREEP data, indicate that different lunar samples are sometimes characterized by distinctly different initial Pb isotopic compositions. U-Th-Pb analyses on nonglassy samples and a glassy separate of soil breccia 70019, and bulk and agglutinate samples of soil 72701 showed that the glassy samples did lose considerable Pb relative to U less than 200 million years ago. These data support the contention of other investigators that vaporization of volatile elements owing to impact events significantly alters the chemistry of the lunar regolith. Metaclastic rock 60315 was reanalyzed and was found to be concordant at 3.93 billion years rather than slightly discordant, as was previously reported.

Nunes, P. D.↗
NASA NTRS1975

The source of sublimates on the Apollo 15 green and Apollo 17 orange glass samples

Elemental analyses of the thin film of micromounds which coat the surfaces of Apollo 15 green glass and Apollo 17 orange glass are reported. It is thought that Zn, Ga, Pb, Cu, Tl, S, F, and Cl condensed as a sublimate on the outside surface of these glass particles in lava fountains about 3.4 and 3.6 b.y. ago (Apollos 15 and 17, respectively). The heavy metals enriched in these samples may have been mobilized in a halide- and sulfide-rich vapor, while the source of these elements and of the glass may be a sulfide- and halide-rich pyroxenite inside the moon. The isotopic composition of lead on the surface of individual particles was determined, and the composition is considered with respect to the evolution of the source region. The lead on the surfaces is similar to lead that has been mixed into other soils and breccias at nearby sites.

Meyer, C., Jr.↗
NASA NTRS1975

Geology of the Taurus-Littrow valley floor

The paper surveys the geology of the Taurus-Littrow valley which is located in a graben that is radial to Mare Serenitatis. The basalt fill is characterized; basalt extrusion in the valley continued until about 3.7 b.y. ago and was quickly followed by deposition of glass beads that formed a mantling unit of probable pyroclastic origin. The glass-bead unit in combination with the overlying regolith forms an unconsolidated surficial deposit with an average thickness of about 14 m. The components of the regolith are described. It is thought that most of the craters are part of a secondary cluster formed by projectiles from Tycho. Age estimates for the central cluster and the light mantle are presented.

Wolfe, E. W.↗
NASA NTRS1978

Emergence of the continents

If early degassing of the Earth produced a global ocean several km deep overlying a global sialic crust, then late heavy bombardment of that crust by basin forming impacting bodies would have produced topography such that by 4 billion years ago dry continential landmasses would stand above sea level. From extrapolation of lunar crater statistics, at least 50% of an original global crust on the earth would have been converted into basins averaging 4 km deep after isostatic adjustment. These basins formed the sink into which such a global ocean would drain. If the ocean was initially 2 km deep, then approximately 50% of the early Earth would have stood above sea level when the late heavy bombardment came to a close.

Frey, H.↗
NASA NTRS1978

Titan's atmosphere: Comments on haze content, methane abundance, band shapes, and hydrogen upper limit

The existence of scatterers in Titan's atmosphere was demonstrated in a paper published in the Astrophysical Journal three years ago. This conclusion was not affected by recent laboratory investigations showing that certain CH4 bands are independent of pressure because it was shown that the reflecting layer model failed to explain Titan's CH4 absorptions regardless on which portion of the curve of growth Titan's CH4 lines lie. Saturn's atmosphere was utilized along the central meridian for studies of CH4 absorption, and to show that the conclusion is insensitive to the moderate scattering there. The quite pronounced role of scattering in Titan's atmosphere strongly suggests that Titan's surface is obscured.

Trafton, L.↗
NASA NTRS1979

Salyut-6--Soyuz-29: Our commentary, the crew and the station

A newspaper article written by an assistant flight director which stresses the importance of cosmonaut training is presented. The preliminary stage of training is discussed, and the training of a crewmaker on a real spacecraft is briefly covered. The success in training foreign cosmonauts by Soviets is also discussed. The author feels that training is even more important today than it was seven or eight years ago because of the increased complexity of the experiments and the length of time a cosmonaut spends in space now.

Kravets, V.↗