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At least 145 records · Page 8

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NASA NTRS1975

Evolution of the moon - The 1974 model

Based on the geological discoveries of the Apollo and Luna missions, the evolution of the moon is divided into seven major stages, beginning at some time near the end of the formation of the solar system. These stages are: (1) the beginning, 4.6 billion years ago (b.y.a.); (2) melting of the outer shell, 4.6 to 4.4 b.y.a.; (3) cratering of the highlands, 4.4 to 4.1 b.y.a.; (4) formation of the large basins, 4.1 to 3.9 b.y.a.; (5) formation of the light-colored plains, 3.9 to 3.8 b.y.a.; (6) formation of the basaltic maria, 3.8 to about 3.0 b.y.a.; and (7) the quiet-crust stage, about 3.0 b.y.a. to the present. Each Apollo and Luna mission is reviewed, emphasizing the most important discoveries and experiments performed. The limits on this interpretative understanding of the moon and the outlined sequence of events are pointed out.

Schmitt, H. H.↗

NASA NTRS1975

Dust injection into the Martian atmosphere

The sequence of events culminating in a global Martian dust storm is reviewed in the light of current theories on dust storm generation. Based upon experimental results, a mechanism for the initiation of global dust storms on Mars is proposed. According to this mechanism, the diurnal variation of surface temperature results in desorption of adsorbed CO2, which under certain conditions can inject large amounts of fine (1-10 microns) dust into the atmosphere.

Johnson, D. W.↗

NASA NTRS1976

The geology and geophysics of Mars

The current state of knowledge concerning the regional geology and geophysics of Mars is summarized. Telescopic observations of the planet are reviewed, pre-Mariner models of its interior are discussed, and progress achieved with the Mariner flybys, especially that of Mariner 9, is noted. A map of the Martian geological provinces is presented to provide a summary of the surface geology and morphology. The contrast between the northern and southern hemispheres is pointed out, and the characteristic features of the surface are described in detail. The global topography of the planet is examined along with its gravitational field, gravity anomalies, and moment of inertia. The general sequence of events in Martian geological history is briefly outlined.

Saunders, R. S.↗

NASA NTRS1977

Television observations of Mercury by Mariner 10

The morphology and optical properties of the surface of Mercury resemble those of the Moon in remarkable detail, recording a very similar sequence of events; chemical and mineralogical similarity of the outer layers is implied. Mercury is probably a differentiated planet with an iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of any landform is found. Large-scale scarps and ridges unlike lunar or Martian features may reflect a unique period of planetary compression near the end of heavy bombardment, perhaps related to contraction of the core.

Murray, B. C.↗

NASA NTRS1977

Volatile metal deposits on lunar soils: Relation to volcanism

Parallel leaching and volatilization experiments conducted on lunar samples and similar experiments on sphalerite do not supply the information needed to resolve the question of the chemical nature of pb 204, Zn, Bi and Tl deposits on lunar soil surfaces. It is proposed that in Apollo 17 mare and terra soils and fractions of pb 204, Zn and Tl that are insoluble under mild, hot pH 5HNO3, leaching conditions and involatile at 600 C were originally surface deposits which became immobilized by migration into the silicate substrate or by chemisorption. Only Bi is predominantly indigenous. The implication is also that the soils over their respective times of evolution were exposed to heavy metal vapors or that an episodic exposure occurred after they had evolved. A sequence of events is proposed to account for orange 74220 and black 74001 glasses by lava fountaining and for soil 74241 as tephra from an explosive volcanic eruption.

Reed, G. W., Jr.↗

NASA NTRS1978

Biochemical adaptations of antigravity muscle fibers to disuse atrophy

Studies are presented in four parts of this report. The four parts include; (1) studies to gain information on the molecular basis of atrophy by antigravity muscle; (2) studies on the work capacity of antigravity muscles during atrophy and during recovery from atrophy; (3) studies on recovery of degenerated antigravity fibers after removal of hind-limb casts; and (4) studies on the atrophy and recovery of bone. The philosophy of these studies was to identify the time sequence of events in the soleus muscle of the rat following immobilization of the hind limbs, so that the length of the soleus muscle within the fixed limb is less than its resting length. In two separate studies, no decline in the weight of the soleus muscle could be detected during the first 72 hours of limb immobilization.

Booth, F. W.↗

NASA NTRS1978

The behavior of a convergent plate boundary - Crustal deformation in the South Kanto district, Japan

The northwesternmost part of the Sagami trough, a part of the Philippine Sea-Eurasian plate boundary, was ruptured during the great South Kanto earthquake in 1923. Very extensive and frequent geodetic measurements of crustal deformation have been made in the South Kanto district since the 1890's, and these constitute the most complete data set on crustal movements in the world. These data were reanalyzed and interpreted and according to our interpretation indicate the following sequence of events. The coseismic movements were due to oblique thrust and right lateral slip of about 8 m on a fault outcropping at the base of the Sagami trough. This was followed by postseismic deformation resulting from reversed afterslip of 20-60 cm that occurred at an exponentially decaying rate in time. The interseismic deformation is produced by steady subduction at a rate of about 1.8 cm/yr. During subduction the top 10-15 km of the plate boundary is apparently locked, while deeper parts slip aseismically at an irregular rate. No significant precursory deformation was observed. The recurrence time for 1923 type earthquakes is 200-300 years. The Boso and Miura peninsulas are broken into a series of fault-bound blocks that move semi-independently of the surrounding region. The subduction zone itself, where it is exposed on land, is shown to be a wide zone encompassing several faults that are active at different times.

Scholz, C. H.↗

NASA NTRS1977

Microbial metabolic activity in soil as measured by dehydrogenase determinations

The dehydrogenase technique for measuring the metabolic activity of microorganisms in soil was modified to use a 6-h, 37 C incubation with either glucose or yeast extract as the electron-donating substrate. The rate of formazan production remained constant during this time interval, and cellular multiplication apparently did not occur. The technique was used to follow changes in the overall metabolic activities of microorganisms in soil undergoing incubation with a limiting concentration of added nutrient. The sequence of events was similar to that obtained by using the Warburg respirometer to measure O2 consumption. However, the major peaks of activity occurred earlier with the respirometer. This possibly is due to the lack of atmospheric CO2 during the O2 consumption measurements.

Casida, L. E., Jr.↗

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

Volatile metal deposits on lunar soils - Relation to volcanism

Parallel leaching and volatilization experiments conducted on lunar samples and similar experiments on sphalerite do not supply the information needed to resolve the question of the chemical nature of Pb-204, Zn, Bi, and Tl deposits on lunar soil surfaces. It is proposed that in Apollo 17 mare and terra soils the fractions of Pb-204, Zn, and Tl that are insoluble under mild, hot pH 5 HNO3, leaching conditions and involatile at 600 C were originally surface deposits which became immobilized by migration into the silicate substrate or by chemisorption. Most of the Bi does not seem to be the result of such a deposit. The implication is also that the soils, over their respective times of evolution, were exposed to heavy metal vapors or that an episodic exposure occurred after they had evolved. A sequence of events is proposed to account for orange 74220 and black 74001 glasses by lava fountaining and for soil 74241 as tephra from an explosive volcanic eruption.

Reed, G. W., Jr.↗

NASA NTRS1979

Voyager program. Voyager 1 encounter at Jupiter, 5 March 1979

Highlights of Voyager 1 activity during the observatory and far-encounter phases are summarized. Daily sequence of events for the spacecraft during the period of greatest encounter activity (Feb. 26 through Mar. 7) the near-encounter phase is given. Times shown designate the time of signal reception at Deep Space Network stations. Events listed emphasize activities pertaining to the four remote sensing instruments on the scan platforms. However, the other 7 experiments will continuously collect data throughout the encounter period.

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NASA NTRS1978

A surface flow visualisation technique for use in cryogenic wind tunnels

A method of surface flow visualization for use in cryogenic wind tunnels is described which requires injection of a cryogenic liquid onto the model while the tunnel is running. This necessitates the use of a substance that remains liquid over a large range of cryogenic wind tunnel operating temperatures. It is found that propane (C3H8) is a suitable substance. Experiments are conducted in a subsonic cryogenic wind tunnel to assess the practical application of liquid propane flow visualization. The propane is stored in a chamber cooled by liquid nitrogen and when required is pumped through pipes to a gallery inside the model and then out onto the surface through small holes. To color the liquid a suspension of pigment particles is used. Propane is supplied to the cooled chamber in gaseous form from a standard liquefied gas cylinder. The sequence of events is illustrated on a propane temperature-entropy diagram. The use of liquefied propane for flow visualization in a cryogenic tunnel operating at pressures up to 40 atm appears to be feasible. Illustrative examples are provided.

Kell, D. M.↗

NASA NTRS1978

Isotopic fractionation of silicon in Allende inclusions

The variations of Si-30/Si-28 and Si-29/Si-28 in Allende inclusions are large, and are due predominantly to mass-dependent fractionation effects. Gas-soild or gas-liquid condensation processes at high temperatures have sufficiently large fractionation factors to account for the heavy-isotope enrichments in coarse-grained inclusions. Heavy isotope depletions are found in some Allende samples, and apparently result from a late-stage condensation. Thus, the silicon isotopic compositions may be useful for determining the sequence of events in forming the Allende meteorite. The peculiar Allende inclusion, Cl, has a very large mass-fractionated enrichment of Si-30/Si-28, and in addition, perhaps a small nuclear enrichment of Si-29. Olivine from the unusual pallasite, Eagle Station, has normal silicon isotope abundances even though it has a large O-16 excess.

Clayton, R. N.↗

NASA NTRS1979

Tensile and flexural strength of non-graphitic superhybrid composites: Predictions and comparisons

Equations are presented and described which can be used to predict bounds on the tensile and flexural strengths of nongraphitic superhybrid (NGSH) composites. These equations are derived by taking into account the measured stress-strain behavior, the lamination residual stresses and the sequence of events leading to fracture. The required input for using these equations includes constituents, properties (elastic and strength), NGSH elastic properties, cure temperature, and ply stress influence coefficients. Results predicted by these equations are in reasonably good agreement with measured data for strength and for the apparent knees in the nonlinear stress-strain curve. The lower bound values are conservative compared to measured data. These equations are relatively simple and are suitable for use in the preliminary design and initial sizing of structural components made from NGSH composites.

Chamis, C. C.↗

NASA NTRS1979

Scientific need for a cometary mission

Known facts about comets are reviewed including their organic and inorganic content. Photographs are used to show the differences in the physical appearances of the three types of comets. Space missions will provide the opportunity to determine the sequence of events that led to their formation and that of the solar system; how volatiles arrived on earth; and the basis for the existence of life on earth; and the source of the outer planetary system.

Whipple, F. L.↗

NASA NTRS1979

Introduction to the Apollo collections: Part 2: Lunar breccias

Basic petrographic, chemical and age data for a representative suite of lunar breccias are presented for students and potential lunar sample investigators. Emphasis is on sample description and data presentation. Samples are listed, together with a classification scheme based on matrix texture and mineralogy and the nature and abundance of glass present both in the matrix and as clasts. A calculus of the classification scheme, describes the characteristic features of each of the breccia groups. The cratering process which describes the sequence of events immediately following an impact event is discussed, especially the thermal and material transport processes affecting the two major components of lunar breccias (clastic debris and fused material).

Mcgee, P. E.↗

NASA NTRS1980

Prelaunch summary: NOAA-B launch

The NOAA-B satellite will launch from the Western Test Range into Sun-synchronous orbit to replace the TIROSN-satellite as part of the national operational environmental satellite system in support of the Global Atmospheric Research Program and the World Weather Watch. The mission objectives, primary environmental sensors, launch particulars, flight sequence of events, mission support, and project costs for NOAA-A through NOAA-G are discussed. NASA's responsibilities include launch, in-orbit evaluation and spacecraft checkout.

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NASA NTRS1979

Shuttle program. STS-7 conceptual flight profile. IUS/TDRS-A

The Space Transportation System (STS) Flight Assignment Manifest has has scheduled a Tracking and Data Relay Satellite System (TDRSS) spacecraft for a February 1981 launch on STS Flight 7. The preliminary flight profile that conceptually implements the flight requirements and constraints levied by the STS, inertial upper stage (IUS), and the TDRS spacecraft is presented. The integrated major flight design guidelines and requirements used in the development of the flight profile are included together with a flight sequence of events and time line that describe the profile and reflect implementation of the integrated set of requirements.

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