Self-destruct charge ordnance component of the Agena D vehicle self-destruct system
Self-destruct explosive charge component of Agena D flight termination system
CHARGE↗
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Grain destruction in shocks in the interstellar medium
Destruction of interstellar dust occurs predominantly in supernova shock waves in the warm neutral/ionized medium (density approximately = 0.25/cu cm, temperature approximately = 10(exp 4) K). Recent theoretical developments and laboratory data for sputtering processes and grain-grain collisional vaporization allows us to better evaluate the grain destruction rate in interstellar shocks in the warm medium. We find that, independent of composition, grain denstruction in supernova blast waves is dominated by nonthermal sputtering for shock velocities greater than 50 km/s and less than or equal to 150 km/s and thermal sputtering at higher shock velocities. We use a detailed scheme for the vaporization of grains colliding at high velocities (v(sub s) greater than or equal to 20 km/s) and show that the grain-grain collision destruction process is only dominant for shock velocities of less than or equal to 50-80 km/s and is less important than previously assumed. Nevertheless, the grain-grain destruction rates are of order 30%-90% of the sputtering rates at v(sub s) greater than 100 km/s and less than 200 km/s and are important in vaporizing the cores of grains. Detailed results for grain destruction as a function of grain size and composition are presented. We also present results for silicon carbide, iron, ice, and porous test particles. For carbonaceous grains we find that the fractional destruction is less than or equal to 0.29, and for silicate it is less than or equal to 0.45, for v(sub s) less than or equal to 200 km/s. We have calculated grain lifetimes, using the three-phase model of the interstellar medium, and find lifetimes of 4 x 10(exp 8) yr for carbonaceous grains and 2.2 x 10(exp 8) yr for silicate grains. Given that the typical stardust injection timescale of 2.5 x 10(exp 9) yr, we conclude that efficient mechanisms for grain growth in the interstellar medium must exist in order that a significant fraction of the refractory elements be incorporated in dust, as observed. Therefore, although our improved model has less vaporization of dust due to grain-grain collisions, sputtering still destroys dust efficiently and grain mantle growth in the interstellar medium is required, a conclusion reached in previous models of grain destruction in the interstellar medium. Carbonaceous mantles on silicate grains can protect the silicate cores from sputtering destruction in interstellar shock waves, provided that the protective mantles can efficiently reform in the interstellar medium. Also, if the grains are porous the postshock grain velocities are lower than for solid particles, and grain destruction is reduced. Porosity and mantling may increase the grain lifetime by factors of approximately 3 and approximately 3-4, respectively. The fraction of interstellar silicon in silicate stardust is therefore less than or equal to 0.25, but more silicon might be depleted in the form of a grain mantle.
Jones, A. P.↗
Conceptual Design of an Experiment to Study Dust Destruction by Astrophysical Shock Waves
A novel laboratory experimental design is described that will investigate the processing of dust grains in astrophysical shocks. Dust is a ubiquitous ingredient in the interstellar medium (ISM) of galaxies; however, its evolutionary cycle is still poorly understood. Especially shrouded in mystery is the efficiency of grain destruction by astrophysical shocks generated by expanding supernova remnants. While the evolution of these remnants is fairly well understood, the grain destruction efficiency in these shocks is largely unknown. The experiments described herein will fill this knowledge gap by studying the dust destruction efficiencies for shock velocities in the range of approximately 10-30 kilometers per second (microns per nanosecond), at which most of the grain destruction and processing in the ISM takes place. The experiments focus on the study of grain-grain collisions by accelerating small (1 millimeter) dust particles into a large (approximately 5-10 millimeter diameter) population; this simulates the astrophysical system well in that the more numerous, small grains impact and collide with the large population. Facilities that combine the versatility of high-power optical lasers with the diagnostic capabilities of X-ray free-electron lasers, e.g., the Matter in Extreme Conditions instrument at the SLAC (originally named Stanford Linear Accelerator Center) National Accelerator Laboratory, provide an ideal laboratory environment to create and diagnose dust destruction by astrophysically relevant shocks at the micron scale.
Manuel, M. J.-E.↗
Do Sub-Mesoscales Inhibit Destruction of PV?
We present the first explicit form of the three components, advective, diabatic and frictional of the PV J fluxes contributed by sub-mesoscales SM. Of particular interest is the surface value of the vertical frictional PV flux which when positive, can induce destruction of PV by down-front winds. The 2005 numerical simulations of Thomas confirmed that this is indeed the case. However, since the 12 km numerical resolution could not account for sub-mesoscales SM (0.1-10) km, the effect of SM on the PV destruction process could not be quantified. The goal of this work is to provide an answer to that question asked in the title. The two SM parameterizations entering the problem, the vertical buoyancy flux and the momentum flux (Reynolds stresses), bring about a new feature, the dependence on the SM kinetic energy (represented by the dimensionless Rossby number Ro), that causes unexpected results. While in the absence of SM, there were no restrictions on where PV destruction could occur, in the presence of SM, the condition of a positive surface vertical frictional flux is restricted to SM regimes with very low Ro<1 and very high Ro>10. Since the SM kinetic energy is location dependent, so is PV destruction. The effect of SM seems to make PV destruction a much rarer occurrence than previously thought.
potential vorticity↗
On the rate of destruction of lithium in late-type main-sequence stars
It it shown that the rate of destruction of lithium by nuclear reactions in the outer mixed layers of late-type main-sequence stars depends on both the depth of the region where mixing occurs and the stratification within it. The mixed region includes and probably extends beneath the base of the convection zone. As the star evolves on the main sequence, the properties of the convection zone vary in a simple manner. If the mixed layer behaves similarly, then the mean destruction rate can easily be related to the present local value evaluated at the base of the mixed layer. In the case of the sun, it is found that if mixing is rapid compared with the nuclear destruction rate, then the mean destruction rate is approximately equal to one-half the present local value.
Christensen-Dalsgaard, J.↗
The Effect of Localized Damage on the Electrical Conductivity of Bare Carbon Fiber Tow and its Use as a Non-Destructive Evaluation Tool for Composite Overwrapped Pressure Vessels
Composite materials are beneficial because of their high specific strength and low weight. Safety, Destructive testing and destructive testing, Non-Destructive Testing (NDT) and Non-Destructive Evaluation (NDE). Problem: Neither NDT nor NDE can provide sufficient data to determine life expectancy or quantify the damage state of a composite material.
Wentzel, Daniel↗
Comparison of Destructive Wind Forces of Hurricane Irma and Other Hurricanes Impacting NASA Kennedy Space Center, 2004-2017
Hurricane Irma produced sustained hurricane force winds (lowest altitude occurrence at 54-ft) resulting in facility damage at Kennedy Space Center (KSC) on September 10-11, 2017. Irma's large destructive wind footprint also caused significant wind damage across the adjacent communities within Brevard County. Wind damage was augmented by frequent gusts of higher magnitude, along with several embedded tornadoes. Hurricanes have previously impacted and produced significant wind damage to infrastructure at KSC as a result of kinetic energy dissipated, in part, through contact with man-made structures. This paper is intended to provide information specific to the destructive force of Hurricane Irma's sustained winds and previous hurricanes of 2004, 2005 and 2016 as calculated from sustained 10 meters per second wind speeds measured from wind towers at KSC for the onset and cessation of destructive forces. Other factors such as pre-existing condition of impacted infrastructure, upstream structures causing turbulent wind patterns, and associated severe convective weather, are contributing factors but are not analyzed here.
Hurricane Irma↗
Destruction of Interstellar Dust
Interstellar dust is an important component of the interstellar medium. Dust grains are the dominant opacity source and thus regulate the radiative transfer in the interstellar medium. Besides the spectral characteristics of sources, dust therefore influences directly the molecular composition of clouds through photodissociation and the heating of the gas through the photoelectric effect. Furthermore, dust grains also provide surfaces for active chemistry. This paper will review the destruction of interstellar dust with an emphasis on processing by interstellar shocks. Interstellar dust is affected by a variety of processes. Stars in the late stages of their evolution form dust grains by chemical nucleation and growth and injected them into the ISM. Grains in the ISM are processed by strong shock waves which sputter, vaporize, diamondize, and shatter them. The physics of interstellar shock waves and of these destruction processes will be reviewed. The ISM is organized in a number of phases: HI and molecular clouds, warm (neutral/ionized) intercloud medium, and coroner gas. Dust destruction is dominated by supernova shock waves in the intercloud medium. Because of rapid exchange of dust and gas between the phases, the effects of this are felt through all phases. This will be briefly discussed.
Tielens, A. G. G. M.↗
Formation and Destruction Processes of Interstellar Dust: From Organic Molecules to carbonaceous Grains
The study of the formation and destruction processes of cosmic dust is essential to understand and to quantify the budget of extraterrestrial organic molecules. interstellar dust presents a continuous size distribution from large molecules, radicals and ions to nanometer-sized particles to micron-sized grains. The lower end of the dust size distribution is thought to be responsible for the ubiquitous spectral features that are seen in emission in the IR (UIBs) and in absorption in the visible (DIBs). The higher end of the dust-size distribution is thought to be responsible for the continuum emission plateau that is seen in the IR and for the strong absorption seen in the interstellar UV extinction curve. All these spectral signatures are characteristic of cosmic organic materials that are ubiquitous and present in various forms from gas-phase molecules to solid-state grains. Although dust with all its components plays an important role in the evolution of interstellar chemistry and in the formation of organic molecules, little is known on the formation and destruction processes of dust. Recent space observations in the UV (HST) and in the IR (ISO) help place size constraints on the molecular component of carbonaceous IS dust and indicate that small (ie., subnanometer) PAHs cannot contribute significantly to the IS features in the UV and in the IR. Studies of large molecular and nano-sized IS dust analogs formed from PAH precursors have been performed in our laboratory under conditions that simulate diffuse ISM environments (the particles are cold -100 K vibrational energy, isolated in the gas phase and exposed to a high-energy discharge environment in a cold plasma). The species (molecules, molecular fragments, ions, nanoparticles, etc) formed in the pulsed discharge nozzle (PDN) plasma source are detected with a high-sensitivity cavity ring-down spectrometer (CRDS). We will present new experimental results that indicate that nanoparticles are generated in the plasma. From these unique measurements, we derive information on the nature, the size and the structure of interstellar dust particles, the growth and the destruction processes of IS dust and the resulting budget of extraterrestrial organic molecules.
Salama, F.↗
Research Performed within the Non-Destructive Evaluation Team at NASA Glenn Research Center
Non-destructive testing is essential in many fields of manufacturing and research in order to perform reliable examination of potentially damaged materials and parts without destroying the inherent structure of the materials. Thus, the Non-Destructive Evaluation (NDE) Team at NASA Glenn Research Center partakes in various projects to improve materials testing equipment as well as analyze materials, material defects, and material deficiencies. Due to the array of projects within the NDE Team at this time, five research aims were supplemental to some current projects. A literature survey of "DE and testing methodologies as related to rocks was performed. Also, Mars Expedition Rover technology was assessed to understand the requirements for instrumentation in harsh space environments (e.g. temperature). Potential instrumentation and technologies were also considered and documented. The literature survey provided background and potential sources for a proposal to acquire funding for ultrasonic instrumentation on board a future Mars expedition. The laboratory uses a Santec Systems AcousticScope AS200 acoustography system. Labview code was written within the current program in order to improve the current performance of the acoustography system. A sample of Reinforced Carbon/Carbon (RCC) material from the leading edge of the space shuttle underwent various non-destructive tests (guided wave scanning, thermography, computed tomography, real time x-ray, etc.) in order to characterize its structure and examine possible defects. Guided wave scan data of a ceramic matrix composite (CMC) panel was reanalyzed utilizing image correlations and signal processing variables. Additional guided wave scans and thermography were also performed on the CMC panel. These reevaluated data and images will be used in future presentations and publications. An additional axis for the guided wave scanner was designed, constructed, and implemented. This additional axis allowed incremental spacing of the previously fixed transducers for ultrasonic velocity measurements.
Burns, Erin A.↗
In-situ Measurements of the Radiolytic Destruction of Glycine in Ices: Applications to the Martian Subsurface
Amino acids and other organic molecules are thought to be easily destroyed on the surface of Mars by the high flux of incident ultraviolet rays or by chemical interactions with oxidizing substances in the soil. However, organic molecules may survive in the subsurface, where chemical processes are driven by penetrating galactic cosmic rays such as MeV protons. Models of the radiation dose as a function of depth on Mars have shown that the contribution of galactic cosmic rays dominates from about one centimeter to a few meters [1 J. Theoretical models have also been published to aid in understanding molecular destruction at these depths, but these usually are based on room-temperature laboratory data, studies of single-component samples, and ex-situ methods of chemical analysis. Recent studies of amino-acid survivability include those involving UV photolysis [2, 3J and gamma radiolysis [4], but nearly all chemical and kinetic analyses from such experiments involved room-temperature measurements on samples irradiated and then removed from sealed containers. We report new laboratory studies of the radiation-induced destruction of glycine-containing ices. In-situ infrared spectroscopy was used to study decay rates as a function of temperature and initial glycine concentrations. Our results indicate that glycine's destruction rate depends on temperature, the presence of H20-ice, and the initial relative abundance of glycine. These trends are not obvious in previous work, suggesting that room-temperature measurements on pure glycine's radiation stability are not directly applicable to Mars and other environments.
Gerakines, Perry A.↗
A Distributive, Non-Destructive, Real-Time Approach to Snowpack Monitoring
This invention is designed to ascertain the snow water equivalence (SWE) of snowpacks with better spatial and temporal resolutions than present techniques. The approach is ground-based, as opposed to some techniques that are air-based. In addition, the approach is compact, non-destructive, and can be communicated with remotely, and thus can be deployed in areas not possible with current methods. Presently there are two principal ground-based techniques for obtaining SWE measurements. The first is manual snow core measurements of the snowpack. This approach is labor-intensive, destructive, and has poor temporal resolution. The second approach is to deploy a large (e.g., 3x3 m) snowpillow, which requires significant infrastructure, is potentially hazardous [uses a approximately equal to 200-gallon (approximately equal to 760-L) antifreeze-filled bladder], and requires deployment in a large, flat area. High deployment costs necessitate few installations, thus yielding poor spatial resolution of data. Both approaches have limited usefulness in complex and/or avalanche-prone terrains. This approach is compact, non-destructive to the snowpack, provides high temporal resolution data, and due to potential low cost, can be deployed with high spatial resolution. The invention consists of three primary components: a robust wireless network and computing platform designed for harsh climates, new SWE sensing strategies, and algorithms for smart sampling, data logging, and SWE computation.
Frolik, Jeff↗
Hypergolic Propellant Destruction Evaluation Cost Benefit Analysis
At space vehicle launch sites such as Vandenberg Air Force Base (VAFB), Cape Canaveral Air Force Station (CCAFS) and Kennedy Space Center (KSC), toxic vapors and hazardous liquid wastes result from the handling of commodities (hypergolic fuels and oxidizers), most notably from transfer operations where fuel and oxidizer are transferred from bulk storage tanks or transfer tankers to space launch vehicles. During commodity transfer at CCAFS and KSC, wet chemical scrubbers (typically containing four scrubbing towers) are used to neutralize fuel saturated vapors from vent systems on tanks and tanker trailers. For fuel vapors, a citric acid solution is used to scrub out most of the hydrazine. Operation of both the hypergolic fuel and oxidizer vapor scrubbers generates waste scrubber liquor. Currently, scrubber liquor from the fuel vapor scrubber is considered non-hazardous. The scrubber liquor is defined as spent citric acid scrubber solution; the solution contains complexed hydrazine I methylhydrazine and is used to neutralize nonspecification hypergolic fuel generated by CCAFS and KSC. This project is a collaborative effort between Air Force Space Command (AFSPC), Space and Missile Center (SMC), the CCAFS, and National Aeronautics and Space Administration (NASA) to evaluate microwave destruction technology for the treatment of non-specification hypergolic fuel generated at CCAFS and KSC. The project will capitalize on knowledge gained from microwave treatment work being accomplished by AFSPC and SMC at V AFB. This report focuses on the costs associated with the current non-specification hypergolic fuel neutralization process (Section 2.0) as well as the estimated costs of operating a mobile microwave unit to treat non-specification hypergolic fuel (Section 3.0), and compares the costs for each (Section 4.0).The purpose of this document is to assess the costs associated with waste hypergolic fuel. This document will report the costs associated with the current fuel neutralization process and also examine the costs of an alternative technology, microwave destruction of waste hypergolic fuel. The microwave destruction system is being designed as a mobile unit to treat non-specification hypergolic fuel at CCAFS and KSC.
Kessel, Kurt↗
Destructive Single-Event Failures in Schottky Diodes
This presentation contains test results for destructive failures in DC-DC converters. We have shown that Schottky diodes are susceptible to destructive single-event effects. Future work will be completed to identify parameter that determines diode susceptibility.
Schottky Diodes↗
Formation and destruction rates of interstellar H2
In the model of Hollenbach et al. (1971), hydrogen molecules are formed on grains. Molecular hydrogen is destroyed by absorption of radiation in the Lyman bands. A study has been conducted regarding the formation and destruction rates of molecular hydrogen. The ultraviolet radiation field has been calculated to determine the rate of molecular hydrogen destruction resulting from absorption in the Lyman bands. An estimate of an upper limit for the molecular hydrogen formation rate is obtained from observations involving stars in which very little molecular hydrogen is observed.
Jura, M.↗
Effect of water vapor on the destruction of ozone in the stratosphere perturbed by ClX or NOx pollutants
Results are presented for a self-consistent one-dimensional coupled flow calculation for Ox, NOx, HOx, ClX, H2O, H2, CH4, H2O2, and N2O densities between 10 and 120 km. The results agree well with observations for the normal midlatitude atmosphere over this altitude range. ClX, NOx, and H2O are varied independently in the model considered. It is shown that the effect of depletion of ozone by ClX is to remove ozone preferentially above 30 km and to lower the altitude of maximum ozone density. This leads to enhanced solar heating of the lower stratosphere and tropopause and suggests the possibility of an increased flux of water into the stratosphere. Increasing water vapor in the stratosphere greatly enhances the rate of destruction of O3 by ClX and also causes an increase in the rate of destruction of O3 in the NOx-perturbed atmosphere.
Liu, S. C.↗
Bioprocessing development: Immune/cellular applications: Anti-Ig autoantibody and complement-mediated destruction of neoplastic cells
This space bioprocessing contract effort was comprised of four general objectives. These were: (1) the evaluation of current separation processes, (2) the identification of problems relevant to the separation of important biologicals, (3) the identification of ground-based assay methods needed for pre- and postflight analysis of space bioprocessing separation technology; and (4) the establishment of methods to determine the efficiency of space bioprocessing separation procedures. Immunology was deemed advantageous to study the diversity of cells and cell products involved and the extensive interest being given to their separation. Upon recognition of a cellular or molecular agent as foreign to the body, the immune system becomes activated to produce cells whose function is to destroy that agent and cell products whose function is to inactivate the agent and assist in its destruction. Long after the agent is removed from the body, some cells remain in a state of readiness to continue these destructive actions specifically against that agent should further exposure to it occur. This is the basis of acquired immunity to disease.
Twomey, J. J.↗