16,132 research outputs found

    Launch vehicle effluent measurements during the August 20, 1977, Titan 3 launch at Air Force Eastern Test Range

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    Airborne effluent measurements within the launch cloud and visible and infrared measurements of cloud physical behavior are discussed. Airborne effluent measurements include concentrations of HCl, Cl2, NO, NOX, and particulates as a function of time during each sampling pass through the exhaust cloud. The particle size distribution was measured for each pass through the cloud. Mass concentration as a function of particle diameter was measured over the size range of 0.05- to 25 micron diameter, and particle number density was measured as a function of diameter over a size range of 0.5 to 7.5 micron. Effluent concentrations in the cloud ranged from about 30 ppm several minutes after launch to about 1 to 2 ppm at 100 minutes. Maximum Cl2 concentrations were about 40 to 55 ppb and by 20 minutes were less than 1.0 ppb. A tabulated listing of the airborne data is given in the appendix. Usable cloud imaging data were limited to the first 16 minutes after launch

    Instrumentation of sampling aircraft for measurement of launch vehicle effluents

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    An aircraft was selected and instrumented to measure effluents emitted from large solid propellant rockets during launch activities. The considerations involved in aircraft selection, sampling probes, and instrumentation are discussed with respect to obtaining valid airborne measurements. Discussions of the data acquisition system used, the instrument power system, and operational sampling procedures are included. Representative measurements obtained from an actual rocket launch monitoring activity are also presented

    Instrument for measuring potentials on two dimensional electric field plots Patent

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    Instrument for measuring potentials on two dimensional electric field plo

    Biophysical, morphological, canopy optical property, and productivity data from the Superior National Forest

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    Described here are the results of a NASA field experiment conducted in the Superior National Forest near Ely, Minnesota, during the summers of 1983 and 1984. The purpose of the experiment was to examine the use of remote sensing to provide measurements of biophysical parameters in the boreal forests. Leaf area index, biomass, net primary productivity, canopy coverage, overstory and understory species composition data are reported for about 60 sites, representing a range of stand density and age for aspen and spruce. Leaf, needle, and bark high-resolution spectral reflectance and transmittance data are reported for the major boreal forest species. Canopy bidirectional reflectance measurements are provided from a helicopter-mounted Barnes Multiband Modular Radiometer (MMR) and the Thematic Mapper Simulator (TMS) on the NASA C-130 aircraft

    Oxygen18 as Tracer in the Catalytic Decomposition of Potassium Chlorate

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    There is evidence that the catalytic action of manganese on the decomposition of potassium chlorate involves an alternate oxidation and reduction of the manganese. This evidence can be tested by enriching the oxygen of the catalyst with oxygen18 isotope. Oxygen liberated from chlorate decomposition with an enriched catalyst should contain oxygen18. Recently Forkushima et al (1) carried out a similar experiment. They enriched potassium chlorate with oxygen18 and decomposed it with Mn02.H20 containing ordinary oxygen. Water was formed from successive portions of the liberated oxygen. The density of this water was less than the density of water prepared from oxygen liberated from KC103 without a catalyst. They concluded that some unstable compound is formed between KC103 and Mn02, and that oxygen is liberated from this compound. They further concluded that only a limited portion of the catalyst is used in the reaction. In the present experiment the manganese dioxide was enriched with oxygen18, and the KC103 was normal. Isotopic ratios of liberated oxygen were determined directly by use of a mass spectrograph

    Effluent monitoring of the December 10, 1974, Titan 3-E launch at Air Force Eastern Test Range, Florida

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    Surface and airborne field measurements of the cloud behavior and effluent dispersion from a solid rocket motor launch vehicle are presented. The measurements were obtained as part of a continuing launch vehicle effluent monitoring program to obtain experimental field measurements in order to evaluate a model used to predict launch vehicle environmental impact. Results show that the model tends to overpredict effluent levels

    Radiochlorine36 as a Tracer in the Decomposition of Potassium Chlorate

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    The thermal decomposition of potassium chlorate has been shown to be complex. Oxygen is evolved and, depending upon the conditions, various quantities of perchlorate are formed. At least two sets of equations have been proposed to explain the reaction. Otto and Fry (5) proposed that potassium chlorate decomposes by two simultaneous reactions

    X-ray Timing of PSR J1852+0040 in Kesteven 79: Evidence of Neutron Stars Weakly Magnetized at Birth

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    The 105-ms X-ray pulsar J1852+0040 is the central compact object (CCO) in SNR Kes 79. We report a sensitive upper limit on its radio flux density of 12 uJy at 2 GHz using the NRAO GBT. Timing using XMM and Chandra over a 2.4 yr span reveals no significant change in its spin period. The 2 sigma upper limit on the period derivative leads, in the dipole spin-down formalism, to an energy loss rate E-dot < 7e33 ergs/s, surface magnetic field strength B_p < 1.5e11 G, and characteristic age tau_c = P/2P-dot > 8 Myr. This tau_c exceeds the age of the SNR by 3 orders of magnitude, implying that the pulsar was born spinning at its current period. However, the X-ray luminosity of PSR J1852+0040, L(bol) ~ 3e33(d/7.1 kpc)^2 ergs/s is a large fraction of E-dot, which challenges the rotation-powered assumption. Instead, its high blackbody temperature, 0.46+/-0.04 keV, small blackbody radius ~ 0.8 km, and large pulsed fraction, ~ 80%, may be evidence of accretion onto a polar cap, possibly from a fallback disk made of supernova debris. If B_p < 1e10 G, an accretion disk can penetrate the light cylinder and interact with the magnetosphere while resulting torques on the neutron star remain within the observed limits. A weak B-field is also inferred in another CCO, the 424-ms pulsar 1E 1207.4-5209, from its steady spin and soft X-ray absorption lines. We propose this origin of radio-quiet CCOs: the B-field, derived from a turbulent dynamo, is weaker if the NS is formed spinning slowly, which enables it to accrete SN debris. Accretion excludes neutron stars born with both B_p 0.1 s from radio pulsar surveys, where B_p 40 Myr) or recycled pulsars. Finally, such a CCO, if born in SN 1987A, could explain the non-detection of a pulsar there.Comment: 8 pages, 3 figures, to appear in The Astrophysical Journa
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