Services provided in support of the planetary quarantine requirements, January - March 1969
Heat shock effects on bacterial spore recovery and Apollo 9, 10, and 11 microbial contamination data
Favero, M. S.↗
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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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Radiative capture of electrons by chlorine, bromine, and iodine atoms.
Radiative capture of electrons by chlorine, bromine and iodine atoms in shock heated plasma seeded with sodium halides from absolute intensities in continuous emission
Rothe, D. E.↗
Absolute gf-values for Fe I and Fe II lines.
Absolute gf values for Fe I and Fe II lines between 3190 and 3315 A measured by spectral absorption through shock heated gas containing Fe
Grasdalen, G. L.↗
Shock synthesis of amino acids in simulated primitive environments
Primitive earth prebiological organic synthesis via amino acids shock heating in atmosphere-simulating gas mixture, suggesting energy sources from atmospheric entry
Bar-Nun, A.↗
Shock-tube measurements of carbon to oxygen atom ratios for incipient soot formation with C2H2, C2H4, and C2H6 fuels
Critical atomic carbon to oxygen ratio measurement for incipient soot formation in shock heated acetylene, ethylene and ethane/oxygen/argon mixtures
Appleton, J. P.↗
Shock-tube measurements of carbon to oxygen atom ratios for incipient soot formation with C2H2, C2H4 and C2H6 fuels
The critical atomic carbon to oxygen ratios, Phi sub C, for incipient soot formation in shock heated acetylene, ethylene, ethane/oxygen/ argon mixtures was measured over the temperature range 2000 K to 2500 K for reactant partial pressures between 0.1 and 0.4 atoms. Absorption of light from a He-Ne laser at 6328A was was used to detect soot. It was observed that the values of Phi sub C for all three fuels increased uniformly with temperature such that at the highest temperatures Phi sub C was considerably greater than unity, i.e. greater than the value of about unity at which solid carbon should have been precipitated on a thermochemical equilibrium basis. Observations were made over periods extending up to about one millisecond, which was well in excess of the time required for the major heat release of the combustion reactions. The relevance of these experimental findings to the problem of soot formation in gas turbine combustion chambers is discussed.
Radcliffe, S. W.↗
Nonequilibrium ionization measurements in hydrogen-helium mixtures
Time-resolved emission measurements of several atomic line and continuum radiation channels were made behind the incident shock wave of an electric arc shock tube. Test times and nonequilibrium ionization times were obtained for shock velocities up to 2.5 X 10,000 m/sec in a 0.2 H2 - 0.8 He gas mixture. The shock-heated test gas was found to be free from driver gas contamination, and the test times were adequate to achieve steady state conditions. An activation energy of 4 eV was obtained from the nonequilibrium ionization time measurements. Modifications of experimental technique to determine the effect of test gas impurity level on ionization time measurements are discussed.
Leibowitz, L. P.↗
Pyrotechnic hazards classification and evaluation program. Electrostatic vulnerability of the E8 and XM15/XM165 clusters, phase 1
A survey of the electrostatic vulnerability of explosive manufacturing plants and recommendations for reducing the vulnerability are discussed. During the course of the investigations, the XM15/XM165 and the E8 launcher were shown to be susceptible to electrostatic ignition. The pyrotechnic hazard of prime concern associated with electrostatics is that of the spark which can be generated. The heat, shock, and ionization produced by the spark can cause ignition of pyrotechnics. However, as a result of the initial ignition tests (XM15 fuse train), changes have been incorporated to make the fusing system relatively safe from premature electrostatic activation.
Source record↗
Shock synthesis of amino acids in simulated primitive environments.
A single pulse shock tube of a uniform bore was used in the experiments. The reaction mixture consisted of 3.3 per cent methane, 11 per cent ethane, and 5.6 per cent ammonia, diluted with ultra-pure argon. The formation of glycine, alanine, valine, and leucine under conditions of shock heating was observed. Thermodynamic relations are discussed together with questions of conversion efficiency.
Bar-Nun, A.↗
Taylor instability in the shock layer on a Jovian atmosphere entry probe.
Investigation of the Taylor instability relative to the dynamical instability whose presence in the shock layer on a spacecraft entering the Jovian atmosphere is to be expected because of the difference in velocity across the shear layer. Presented calculations show that the Taylor instability at the interface between shock-heated freestream gas and ablation products is inconsequential in comparison to the shear layer instability.
Compton, D. L.↗
Atmospheric helium and geomagnetic field reversals.
The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.
Sheldon, W. R.↗
Impact of space shuttle orbiter reentry on mesospheric NOx.
Shuttle orbiter reentry will produce large amounts of nitric oxide (NO) through shock heating at mesospheric altitudes. The effects of this reentry are modeled by considering an impulsive source of NO in time-dependent equations including photochemistry and transport. The model uses an odd-nitrogen approach similar to Strobel's. Parameterized flux boundary conditions are imposed at the mesopause and stratopause and concentrations of the odd nitrogen species (NO, NO2, NO+, N(4S) and N(2D) are found numerically by a finite difference scheme. A localized disturbance can last many hours, depending on the effectiveness of eddy transport. Although the model is one-dimensional, effects of horizontal transport are also included approximately.
Stolarski, R. S.↗
Ultrasonic thermometry using pulse techniques.
Ultrasonic pulse techniques have been developed which, when applied to inert gases, provide temperature measurements up to 8000 K. The response time can be less than 1 msec. This is a significant feature in studying shock-heated or combusting gases. Using a momentary contact coupling technique, temperature has been measured inside steel from 300 to 1500 K. Thin-wire sensors have been used above 2000 K in nuclear and industrial applications where conditions preclude the use of thermocouples, resistance devices, or optical pyrometers. At 2500 K, temperature sensitivity of 0.1% is obtained in Re wire sensors 5 cm long by timing five round trips with an electronic instrument that resolves the time interval between selected echoes to 0.1 microsec. Sensors have been operated at rotational speeds over 2000 rpm and in noisy environments. Temperature profiling of up to ten regions using only a single guided path or beam has also been accomplished.
Lynnworth, L. C.↗
Measurements of hydrogen-helium radiation at shock-layer temperatures appropriate for Jupiter entry.
Shock waves traveling at approximately 16 km/sec into a gas mixture of 7% H2 and 93% He were used to simulate the shock-layer conditions for a representative shallow entry into the Jovian atmosphere. The absolute intensities of line and continuum radiation were measured and the radiative cooling of the shock-heated gas is shown.
Cooper, D. M.↗
Recommended radiative property data for Venusian entry calculations
A compilation of experimental and calculated data on the radiative properties species important in Venusian entry is presented. Molecular band systems, atomic lines, free-bound, and free-free continua are considered for the principal radiating species of shock heated carbon dioxide. A limited amount of data pertinent to the species in the ablation layer is also included. The assumption is made that the Venus atmosphere so closely approximates pure CO2 that the inviscid layer radiation is due almost entirely to thermally excited CO2. The only exception is the inclusion of data on the Violet band system of CN. Recommendations are made as to best property values for radiative heating calculations. A review of the basic equations and the relationships of the various emission-absorption gas porperties is also included.
Jones, J. J.↗
Hook-method measurements of gf-values for ultraviolet Fe I and Fe II lines on a shock tube
Transition probabilities for 14 lines of Fe II and 12 lines of Fe I in the wavelength region 2560-2737 A were measured by use of a shock tube and the hook method. Absolute oscillator strengths for resonance lines of Fe I reported by Banfield and Huber were used to determine the number density of neutral iron in the shock-heated gas. With the assumption of thermal equilibrium, the density of singly ionized iron atoms in this gas was then computed from the measured temperature and pressure with the aid of the Saha equation. Our results on the 12 strongest of the 13 lines belonging to the first ultraviolet multiplet of Fe II indicate that the multiplet f-value is larger by a factor of 2 than that derived from lifetime measurements by Assousa and Smith.
Huber, M. C. E.↗
Radiative property data for Venusian entry: A compendium
A compilation of experimental and calculated data on the radiative properties of species important in Venusian entry is presented. Molecular band systems, atomic lines, free-bound continua, and free-free continua are considered for the principal radiating species of shock-heated carbon dioxide. Data pertinent to the species in the ablation layer are included. The Venus atmosphere so closely approximates pure carbon dioxide (CO2) that the inviscid layer radiation is due almost entirely to thermally excited CO2. Data are included on the violet band system of the cyanogen radical CN. Recommendations are made as to best property values for radiative heating calculations. A review of the basic equations and the relationships of the various emission-absorption gas properties is included.
Jones, J. J.↗
Glass production differences for equal-diameter impact craters
A thermodynamic model of meteorite impact is used to investigate the possibility that the creation of two impact craters of the same apparent diameter may have been accompanied by dissimilar shock heating regimes. For small craters, the idea may be concisely represented by the question of which event produces more glass, a large slow meteorite or a small fast one, if the resulting craters are of the same diameter. So that the results may be most apparent, the only parameters varied in this study are meteorite size and impact velocity. Identical basaltic material is assumed for meteorite and target. For impact velocities between 10 and 70 km/sec, an available model determines the radius of a spherical meteorite which would produce a crater diameter of 20 cm.
Rehfuss, D. E.↗