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Tetraethyl orthosilicate (TEOS) mixture fills chips and cracks in glazed tile surface. Filler is made by mixing hydrolyzed TEOS, silicon tetraboride powder, and pulverized tile material. Repaired tiles survived testing by intense acoustic emissions, arc jets, and intense heat radiation. Repair is reliable and rapid, performed in 1-1 1/2 hours with tile in any or orientation.
The major observational features of one new component of Jupiter's radio emission spectrum, the broadband kilometer-wavelenth radiation or bKOM are described. The Voyager planetary radio astronomy experiments reveal that the overall occurrence morphology, total power, and polarization character of bKOM are strong functions of the latitude and/or local time geometry of the observations. The post-encounter data show a decline in the mean occurrence rates and power level of bKOM and, in particular, a depletion in the occurrence rate at those same longitudes where the detection rate is a maximum before encounter. Additionally, the polarization sense undergoes a permanent reversal in sign after encounter, whereas the time-averaged wave axial ratio and degrees of polarization remain relatively unchanged. No evidence of any control by Io is found. The strong dependence of the morphology on local time suggests a source whose beam is nearly fixed relative to the Jupiter-sun line.
Preliminary results of the infrared radiometer experiment on Pioneer Saturn are reported. The instrument made use of two broadband channels centered at 20 and 45 microns which scan at a fixed 75-deg angle with respect to the spacecraft spin axis to acquire 10,000 image pairs of Saturn and its rings in the 2.5 h before closest approach, as well as several observations of Titan. The intensities of radiation observed in both bands indicate an effective temperature of 94.4 + or - 3 K for the planet, implying a total emission greater than twice the absorbed sunlight. Infrared data also indicates a molecular abundance of 0.85 for H2 relative to H2 + He, which can be improved by comparing the derived temperature profiles and radio occultation data. Planetary temperatures are found to range from a minimum of 83 to 140 K at the 1 bar level, with differences of 2.5 K between belts and zones up to the 0.06-bar level, while ring temperatures range from 60 to 70 K on the illuminated side and from less than 60 to 67 K in the planet's shadow and average 55 K on the unilluminated side. Preliminary estimates indicate a 45-micron brightness temperature of 80 + or - 10 K for Titan.
The paper describes the major observational features of one new component of Jupiter's radio emission spectrum, the broadband kilometer wavelength radiation, or bKOM. This study, using the Voyager Planetary Radio Astronomy (PRA) experiments, reveals that the overall occurrence morphology, dynamic spectra, and polarization character of bKOM are strong functions of the latitude and/or local time geometry of the observations. The postencounter data show a decline in the mean occurrence rates and power level of bKOM and, in particular, a depletion in the occurrence rate at those same longitudes where the detection rate is a maximum before encounter. Additionally, the polarization sense undergoes a permanent reversal in sign after encounter, whereas the time-averaged wave axial ratio and degree of polarization remain relatively unchanged. Finally, no evidence of any control by Io is found. The strong dependence of the morphology on local time suggests a source whose beam is nearly fixed relative to the Jupiter-sun line
Implementation of SOLARES will input large quantities of heat continuously into a stationary location on the Earth's surface. The quantity of heat released by each of the SOlARES ground receivers, having a reflector orbit height of 6378 km, exceeds by 30 times that released by large power parks which were studied in detail. Using atmospheric models, estimates are presented for the local weather effects, the synoptic scale effects, and the global scale effects from such intense thermal radiation.
A technique is described for obtaining passive microwave measurements from space with high spatial resolution for remote sensing applications. The technique involves measuring the product of the signal from pairs of antennas at many different antenna spacings, thereby mapping the correlation function of antenna voltage. The intensity of radiation at the source can be obtained from the Fourier transform of this correlation function. Theory is presented to show how the technique can be applied to large extended sources such as the Earth when observed from space. Details are presented for a system with uniformly spaced measurements.
It is now reasonably well established that the intense noise radiated by a single turbulent, heated, under or overexpanded round jet of high specific thrust can be significantly reduced if instead, 'equivalent' multinozzle coaxial supersonic jet flows of the same total thrust and mass flow rate were to be operated in the inverted pressure mode. A summary of some of the relevant observations on the coaxial supersonic jet flows and their shock structure is presented. Attention is given to the scope of the optical studies, the development of shock structure, the effects of exit stagger, coaxial supersonic jet flows with inner nozzle overexpanded, the role of the lip thickness, the role of the exit area ratios, cold/heated coaxial supersonic jet flows, acoustic observations, the conventional pressure mode of operation, comparative noise reduction assessment, and problems and prospects of noise prediction.
It is pointed out that most advances of cosmic-ray physics have been directly related to the development of observational techniques. A review is presented of the history of the evolution of the techniques and equipment for the study of cosmic-ray physics, taking into account the new scientific advances accompanying each new development related to experimental technology. All of the early observations were performed by means of ionization chambers. These chambers had already been in use for a number of years, when they were first applied to the study of cosmic rays in the early years of this century. However, an application to the low-intensity cosmic radiation required special refinements. Attention is given to the design of suitable electrometers, the development of self-recording instruments, the 'tube counter', the development of the coincidence method, a cosmic-ray 'telescope', a magnetic lens for cosmic rays, an arrangement of Geiger-Mueller counters for the demonstration of secondary radiation, cloud chambers, scintillation counters, and air shower experiments.
The performance of the infrared (IR) rig used for the thermal balance testing of the Olympus S/C thermal model is discussed. Included in this evaluation are the rig effects themselves, the IRFLUX computer code used to predict the radiation inputs, the Monitored Background Radiometers (MBR's) developed to measure the absorbed radiation flux intensity, the Uniform Temperature Reference (UTR) based temperature measurement system and the data acquisition system. A preliminary set of verification tests were performed on a 1 m x 1 m zone to assess the performance of the IR lamps, calrods, MBR's and aluminized baffles. The results were used, in part, to obtain some empirical data required for the IRFLUX code. This data included lamp and calrod characteristics, the absorptance function for various surface types, and the baffle reflectivities.
Observations from two dates 5 Jan. and 7 Jan. 1986 are presented. The images were obtained with the Durham imaging polarimeter on the 1-m telescope of the Wise Observatory, Israel. The observations were made through a broadband filter centered at 0.67 microns with a 0.17 micron effective bandwidth. This wavelength region should be dominated by continuum radiation. The intensity images cover 46 x 78 arcsecs. The intensity images are shown in logorithmic form and they are analyzed.
Four problems were defined which had aspects which would be reasonably assigned to an interdisciplinary design team. The design problems are: (1) design of a thermal shield for a lunar telescope (thermal protection for a lunar telescope); (2) selenotextile shielding structure (a structure to protect a lunar habitat from intense solar radiation of tubes of woven polytetrafluoroethylene coated fiberglass fabric); (3) pneumatically assisted elbow joint design for the NASA Zero-prebreathe suit (will allow astronauts to make the transition from a high pressure internal environment to a lower pressure suit without spending time in an air lock); and (4) electrochemical system to power assist an astronaut's finger joints (assist in the movement of an astronaut's distal and proximal interphalangeal finger joints).
The Heavy Ions In Space (HIIS) experiment has two primary objectives: (1) to measure the elemental composition of ultraheavy galactic cosmic rays, beginning in the tin-barium region of the periodic table; and (2) to study heavy ions which arrive at LDEF below the geomagnetic cutoff, either because they are not fully stripped of electrons or because their source is within the magnetosphere. Both of these objectives have practical as well as astrophysical consequences. In particular, the high atomic number of the ultraheavy galactic cosmic rays puts them among the most intensely ionizing particles in Nature. They are therefore capable of upsetting electronic components normally considered immune to such effects. The below cutoff heavy ions are intensely ionizing because of their low velocity. They can be a significant source of microelectronic anomalies in low inclination orbits, where Earth's magnetic field protects satellites from most particles from interplanetary space. The HIIS results will lead to significantly improved estimates of the intensely ionizing radiation environment.
The wavefunction of a system is explicitly written down in a fully anti-symmetric way between a fermion pair and a medium, and the equations for each one of them are derived from the variation of total energy for bound systems and by forming appropriate scalar products for continuum states. High-energy particles, such as protons, electrons, and nuclei impinging upon spacecraft, produce secondary radiations. In order to protect the internal environment of spacecraft from these radiations, their intensities are determined in many instances theoretically, and an appropriate program has been developed in the High Energy Science Branch. The purpose of this research is to investigate the problem of indistinguishability of an incident projectile with one of the same in a target.
Infrared spectra of dusty galactic environments often contain emission features attributed to polycyclic aromatic hydrocarbons or PAHs, which can be considered to be very small grains or very large molecules. Although IR spectra of starburst galaxies almost always show these emission features, similar spectra of active galaxies are usually featureless. Even in those active galaxies that do exhibit PAH emission, the PAHs still appear to be eradicated from the nuclear region. This dichotomy suggests that PAHs are destroyed by the intense hard radiation field from an AGN. Laboratory experiments show that certain PAHs are, in fact, so effectively destroyed by individual EUV and X-ray photons that they cannot survive even at kiloparsec distances from active nuclei. Regions within active galaxies that do show PAH emission must therefore be shielded from the central X-ray source by a substantial column density of X-ray absorbing gas.
New spectroscopic observations are presented that elucidate the spatial distribution, kinematics, and density structure of atomic and molecular gas within about 2 p from IRS 16/SgrA*. The measurements confirm the presence of a dense clumpy molecular gas ring surrounding a short-lived central cavity of much lower mean gas density. It appears that this ring consists of several distinct and probably short-lived gas streamers that result from accretion from the massive molecular clouds within 10-30 pc of the center toward the central gravitational potential. Within 1 pc of SgrA* a large atomic cloud is found that appears to be falling in from more than 3 pc Galactocentric distance into the central cavity. The northern and eastern 'arms' of ionized gas are very likely dense bright rims at the surface of this atomic cloud that is now exposed to the intense UV radiation from the few central arcsec surrounding IRS 16/SgrA*.
The present work reports on the recently completed infrared thermal balance/thermal vacuum testing of a MSAT satellite, the first satellite to provide mobile communications service for all of continental North America. MSAT is a two spacecraft program, using a three-axis stabilized Hughes HS-601 series Bus as the vehicle for the Canadian designed Payload. The thermal tests which were performed at the Canadian Space Agency's David Florida Laboratory in Ottawa, Canada, lasted approximately 35 days. The infrared (IR) heating rig was designed to provide radiant heat inputs into seven spacecraft zones during Thermal Vacuum (TV) testing. The TV test was divided into multiple phases. It began with a thermal balance cold phase, followed by a thermal cold cycle and a hot balance phase, complemented by a thermal hot cycle to finish with a thermal cycle with continuous monitoring of the Bus and Payload. The spacecraft's external heat fluxes were provided by IR lamp sources. To ensure flux uniformity, highly reflective baffles and IR East and West faces; the Earth facing (Nadir); and the inside of the thrust cylinder. The aft-end panel heat fluxes were provided by a heated LN2 shroud. The radiation flux intensity on the spacecraft zones from the various rig elements was measured using Monitored Background Radiometers (MBR's) and compared with direct calculations and with pretest predictions. The temperature measurement system was based on Uniform Temperature References (UTR's) located inside the chamber such that all feedthroughs were copper-copper. This system was devised to achieve a temperature measurement accuracy of plus/minus 0.5 C for over 850 thermocouples used in the test. A PC-(QNX-based) based real-time data acquisition system was utilized to provide continuous monitoring of all channels based on a 30-second time scan. In addition, the data acquisition system was able to retrieve telemetry stream from the Satellite Test Equipments (STE) station for real-time data manipulation. Preliminary results showed the test to be successful from both the thermal balance side and the electrical testing side.
We present Very Large Array measurements of H110 alpha radio recombination line emission from Sgr A West with a resolution of 11 x 20 arcsec. These observations detected a number of new kinematic components showing a dramatically different velocity field than expected from circular motion of ionized gas in Sgr A West about the dynamical center of the Galaxy. Recent high-resolution molecular observations show a cloud of absorbing gas at -180 km/s within 30 arcsec of the Galactic center. We find evidence of an ionized counterpart to this highly blueshifted molecular gas. This result places this highly blueshifted neutral gas in a hot UV dominated environment of the Galactic center. We suggest that the blueshifted clouds are photoionized externally by the intense UV radiation field at the Galactic center. We also detect H110 alpha emission from large-scale linear features known as the 'streamers', which run primarily perpendicular to the Galactic plane and lie exterior to the 'three-arm' spiral structure of Sgr A West and the circumstellar disk. These observations support an earlier suggestion that the streamers are thermal features whose kniematics deviate from circular motion.
Mesoscale Periodic Array Structures (MPAS, also known as crystalline colloidal arrays), composed of aqueous or nonaqueous dispersions of self-assembled submicron colloidal spheres are emerging toward the development of advanced optical devices for technological applications. This is because of their unique optical diffraction properties and the ease with which these intriguing properties can be modulated experimentally. Moreover our recent advancements in this area which include 'locking' the liquid MPAS into solid or semisolid polymer matrices for greater stability with longer life span, and incorporation of CdS quantum dots and laser dyes into colloidal spheres to obtain nonlinear optical (NLO) responses further corroborate the use of MPAS in optical technology. Our long term goal is fabrication of all-optical and electro-optical devices such as spatial light modulators for optical signal processing and flat panel display devices by utilizing intelligent nonlinear periodic array structural materials. Here we show further progress in the design of novel linear MPAS which have the ability to sense and respond to an external source such as temperature. This is achieved by combining the self-assembly properties of polymer colloidal spheres and thermoshrinking properties of smart polymer gels. At selected temperatures the periodic array efficiently Bragg diffracts light and transmits most of the light at other temperatures. Hence these intelligent systems are of potential use as fixed notch filters optical switches or limiters to protect delicate optical sensors from high intensity laser radiation.