Supernovae and the extinction of the dinosaurs
Supernova explosion or solar outburst theory of climatic effects on mass extinction of organisms at Cretaceous-Tertiary boundary
Russell, D.↗
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Results for “Tucker”
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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Extragalactic X-ray sources and associations of galaxies
Extragalactic cosmic X ray sources at high galactic latitude from sounding rocket experiments, correlating with galactic clusters
Cavaliere, A. G.↗
A blast-wave model for the Vela X supernova remnant and the origin of the Gum Nebula
Vela X supernova remnant blast wave model and Gum Nebula formation, discussing kinetic and rotational energy transformation into radiation
Tucker, W. H.↗
Radiation from a high-temperature, low-density plasma - The X-ray spectrum of the solar corona
Solar coronal X ray spectrum calculation of high- temperature low-density plasma, considering line emission from electron collisional excitation and radiation
Koren, M.↗
Laboratory measurement of the 6-centimeter formaldehyde transitions
Formaldehyde transitions in ground and excited states at 6 cm, attaining line widths and hyperfine structure at 1-3 kHz
Thaddeus, P.↗
A method for estimating the components of lift of wing-body combinations at supersonic speeds
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Tucker, W. A.↗
Apollo experience report: Command and service module environmental control system
A comprehensive review is presented of the design philosophy of the Apollo environmental control system together with the development history of the total system and of selected components within the system. In particular, discussions are presented relative to the development history and to the problems associated with the equipment cooling coldplates, the evaporator and its electronic control system, and the space radiator system used for rejection of the spacecraft thermal loads. Apollo flight experience and operational difficulties associated with the spacecraft water system and the waste management system are discussed in detail to provide definition of the problem and the corrective action taken when applicable.
Samonski, F. H., Jr.↗
Natural Resource Information System, remote sensing studies
Potential applications of remote sensing data were reviewed, and available imagery was interpreted to provide input to a demonstration data base. A literature review was conducted to determine the types and qualities of imagery required to satisfy identified data needs. Ektachrome imagery available over the demonstration areas was reviewed to establish the feasibility of interpreting cultural features, range condition, and timber type. Using the same imagery, a land use map was prepared for the demonstration area. The feasibility of identifying commercial timber areas using a density slicing technique was tested on multispectral imagery available for a portion of the demonstration area.
Leachtenauer, J.↗
Mechanism for the X-ray pulsations in Cyg X-1.
The mechanism proposed involves the occurrence of a flare in a region of high magnetic field on the surface of a star. The flare produces oscillations in the magnetic field structure. The oscillations lead to heating of the plasma in a flux tube which emits thermal radiation. The heating may be caused by magnetic pumping or particles accelerated in periodic bursts by the flare. Synchrotron radiation from high energy particles accounts for the hard X-ray emission.
Blumenthal, G. R.↗
A model for the Centaurus X-3 phenomenon.
Description of a model for Cen X-3 according to which the X-ray emission comes from an atmosphere heated by shock waves produced by surface pulsations of a white dwarf. This model can explain the luminosity, period, and spectrum of Cen X-3. The way in which these quantities vary with pulsation period and amplitude is discussed.
Blumenthal, G. R.↗
Laboratory measurement of the 2-centimeter, 2/11/-2/12/ transition of normal formaldehyde and its carbon-13 and oxygen-18 species.
Beam-maser spectrometric measurements to an accuracy of about 100 Hz have been conducted of the 2(11)-2(12) transition for the isotopic species of greatest astronomical interest - i.e., H2CO, H2(13)CO, and H2C(18)O. The samples used were not isotopically enriched, monomeric formaldehyde vapors. For these species, all the coupling constants required to calculate the hyperfine structure of any rotational transition have been determined.
Tucker, K. D.↗
Relationship between X-ray luminosity and velocity dispersion in clusters of galaxies.
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Solinger, A. B.↗
On a galactic origin for the soft X-ray background.
Previous observations and some new data with high angular resolution are considered in the discussion of the galactic origin for the X-ray background. Aspects of instrumentation are discussed together with the observational results, and the parameters of a possible galactic distribution of point sources that would explain essentially all of the soft X-ray background. The excess flux at the poles is accounted for by the fact that the galactic distribution has a larger scale height than the interstellar gas.
Gorenstein, P.↗
Fan noise suppression
The principal suppressor parameters and their relationships have been used to formulate a suppressor design methodology which has been applied to the design of several full-scale suppressors. Tests of these suppressors on several full-scale fans have demonstrated noise reductions of the order of 10 PNdB. The amount of suppression in several instances seems to have been limited by reaching noise floors that are not clearly at the estimated jet noise level but are not far above it. In addition to identifying noise floors, two other areas are considered. The first is attenuation by the fan exhaust suppressors, which seems in most cases to be less than that of the inlet. The second is the effectiveness of outer cowl treatment alone on multiple pure tones. This question relates to whether a high-speed fan can become as quiet as a low-speed fan without a substantial increase in the amount of treatment.
Feiler, C. E.↗
Variable features on Mars 2: Mariner 9 global results
Mariner 9 observations of time variable Martian dark areas and semi-tone areas are commonly resolved into streaks and splotches caused by sand storm particles. Bright streaks are formed by the smaller particles and require exceptionally high velocities for their formation as compared with the more easily saltated larger particles in dark streak areas.
Sagan, C.↗
Variable features on Mars - Preliminary Mariner 9 television results.
Systematic Mariner 9 photography of a range of Martian surface features, observed with all three photometric angles approximately invariant, reveals three general categories of albedo variations: (1) an essentially uniform contrast enhancement due to the dissipation of the dust storm; (2) the appearance of splotches, irregular dark markings at least partially related to topography; and (3) the development of both bright and dark linear streaks, generally emanating from craters. Some splotches and streaks vary on characteristic timescales of about two weeks; they have characteristic dimensions of kilometers to tens of kilometers. The morphology and variability of streaks and splotches, and the resolution of at least one splotch into an extensive dune system, implicate windblown dust as the principal agent of Martian albedo differences and variability.
Sagan, C.↗
Hyperfine structure of furan.
The hfs of five rotational transitions of furan (C4H4O) has been resolved with a beam maser spectrometer with a resolution of about 500 Hz. All significant details of the observed structure are accounted for by the spin-spin and spin-rotation interactions of the four protons, and the coupling constants for these interactions have been determined to high precision. In particular, the diagonal elements of the spin-rotation tensors have been determined to about 10 Hz.
Tomasevich, G. R.↗