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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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Background gamma ray observations attributed to decay of pi-mesons produced by extragalactic cosmic ray protons collisions, noting radiation sources age
A multispectral, variable magnification, glancing incidence, x-ray telescope capable of broadband, high resolution imaging of solar and stellar x-ray and extreme ultraviolet radiation sources is discussed. The telescope includes a primary optical system which focuses the incoming radiation to a primary focus. Two or more rotatable mirror carriers, each providing a different magnification, are positioned behind the primary focus at an inclination to the optical axis. Each carrier has a series of ellipsoidal mirrors, and each mirror has a concave surface covered with a multilayer (layered synthetic microstructure) coating to reflect a different desired wavelength. The mirrors of both carriers are segments of ellipsoids having a common first focus coincident with the primary focus. A detector such as an x-ray sensitive photographic film is positioned at the second respective focus of each mirror so that each mirror may reflect the image at the first focus to the detector at the second focus. The carriers are selectively rotated to position a selected mirror for receiving radiation from the primary optical system, and at least the first carrier may be withdrawn from the path of the radiation to permit a selected mirror on the second carrier to receive the radiation.
We present the initial results of a program to obtain high resolution images of Seyfert galaxies with the Planetary Camera aboard the Hubble Space Telescope (HST). In this paper we discuss the images of the type 2 Seyfert NGC 5929 and the type 1.5 Seyfert MCG 8-11-11 (= UGC 3374). The images were obtained in the emission lines of (O III) lambda lambda 4959 and 5007 A and H alpha + (N II) lambda lambda 6548 and 6583 A and their adjacent continua. The high-excitation gas in the narrow line region (NLR) of NGC 5929 is resolved into individual clouds in the central 1 sec .5. Although the (O III) emission is clearly not spherically symmetric with respect to the nucleus, it does not define a distinct 'bicone' morphology, as observed by the HST in a few other Seyfert galaxies. We find no direct evidence for the reddening and/or obscuration effects characteristic of a dusty torus, which, in the context of 'unified models', is expected to obscure the active galactic nucleus (AGN) in type 2 Seyfert galaxies. The correspondence between the emission line gas and the radio morphology suggests that the structure of the NLR in NGC 5929 is governed by matter ejected from the AGN. A comparison of the recombination rate of hydrogen in the brightest emission line cloud with an upper limit on the ionizing luminosity emitted toward Earth provides no evidence that the central ionizing source radiates anisotropically. The images of MCG 8-11-11 show only an unresolved nuclear source. No emission line gas associated with the extended radio source is detected. We estimate upper limits on the intensity of extended line emission in this galaxy and examine their significance.
Radiographic equipment incorporates two radiation sources, generating high-energy and low-energy beams. Recording equipment measures amount of radiation that has penetrated limb. Data are fed into computer that determines mass of the examined bone.
Operation Aurorozone was a highly coordinated sequence of 33 rocket flights launched from Poker Flat, Alaska, in September 1976. The effects of aurorally produced X-rays on stratospheric neutral and electrical parameters was studied. The sun/weather coupling between upper and lower regions of the atmosphere is thought to be related to these middle atmospheric parameters. The results show a consistent depletion of ozone above 1 mb during three independent auroral events, with magnitudes in excess of those expected from the measured energy radiation sources. Simultaneously, enhanced conductivity changes were observed to occur in accord with the measured ionizing radiations.
An introductory progress report is given on a research project to use the microwave Doppler velocimeter technique to measure the combustion response to an oscillating thermal radiation source (laser). The objective is to relate the measured burning rate response to the thermal radiation to an equivalent oscillation in pressure using existing thermal combustion theory. The test system is described, and the results of an initial test series on the composite propellant A-13 are presented.
A unique structure for constructing the emissive patch of a spaceborne radiative cooler is shown. The structure has very high emissivity for all angles up to a designed-in maximum angle and near zero emissivity for greater angles. The structure also allows the use of high emissivity, nonconducting paints while fully complying with the NASA Electrostatic Discharge Susceptibility requirements for spacecraft. To accomplish these tasks, two previous disadvantages of prior art methods are addressed; eliminating background thermal radiation sources and problems concerning the high emissivity paints used in association with the black body radiator. A reflector consisting of an array of parabolic concentrators is separated from a black body element by an electrically conductive spacer. The concentrators serve to limit the field of view while the conductive spacer eliminates the need to use a conductive paint on the emissive element.
An analytical solution is presented for determining the optimum location of a radiating source on the surface of a sphere, given multiple bearings. The bearings are assumed to have small errors of the order of 0-10 deg. The optimum location is found by minimizing the sum of the squares of the perpendicular great-circle distances from the source to the bearing lines. This is achieved analytically through an eigenvalue approach, rather than the usual iterative, numerical approach. Bearings of different weight are taken into account by approximating the distance from each direction finder to the source. The result is general and may have wide application. Since it is simple and nearly as fast as the triangulation technique for source location, it is now used in the SUNY-Albany East Coast Lightning Detection Network to compute the optimum location for lightning in real time.
Cyanide and pulsed lasers as possible coherent sources of infrared radiation
A one-speed Boltzmann transport theory, with diffusion approximations, is applied to study the radiative transfer properties of lightning in optically thick thunderclouds. Near-infrared (lambda = 0.7774 micrometers) photons associated with a prominent oxygen emission triplet in the lightning spectrum are considered. Transient and spatially complex lightning radiation sources are placed inside a rectangular parallelepiped thundercloud geometry and the effects of multiple scattering are studied. The cloud is assumed to be composed of a homogeneous collection of identical spherical water droplets, each droplet a nearly conservative, anisotropic scatterer. Conceptually, we treat the thundercloud like a nuclear reactor, with photons replaced by neutrons, and utilize standard one-speed neutron diffusion techniques common in nuclear reactor analyses. Valid analytic results for the intensity distribution (expanded in spherical harmonics) are obtained for regions sufficiently far from sources. Model estimates of the arrival-time delay and pulse width broadening of lightning signals radiated from within the cloud are determined and the results are in good agreement with both experimental data and previous Monte Carlo estimates. Additional model studies of this kind will be used to study the general information content of cloud top lightning radiation signatures.
The evolution and appearance of protostellar disks can be significantly altered by their UV environment. We follow the evolution after the external UV radiation source has been turned on.
The possibility of localizing sources of electromagnetic radiation by measurement of the time of passage of the radiation or the measurement of its phase at various points of cosmic space, at which are located satellite observatories is examined. Algorithms are proposed for localization using two, three, and four astronomical observatories. The precision of the localization and several partial results of practical significance are deduced.
The effects of ionizing radiation emitted by quasi-stellar objects on intergalactic hydrogen are studied. The hydrogen is assumed to expand with the Universe, and the amount of ionizing radiation is estimated from observations of the QSO luminosity function. The discreteness of the radiation sources is taken into account in computing the thermal history of the medium. The amount of ionizing radiation is shown to be sufficient to allow the existence of a universal medium with a temperature less than 10,000 K and a density several times the smeared-out density of luminous matter in galaxies. Such a medium would escape detection with presently available techniques.
Outside earth's protective magnetosphere crew members and sensitive equipment need to be protected against two primary radiation sources, namely Galactic Cosmic Rays (GCR) and Solar Energetic Particles (SEP). For planetary missions, this combination of radiation particles could result in doses that are higher than the allowable level currently permitted for low-earth orbit manned missions. This SBIR project aims to develop a multifunctional and lightweight composite material that not only provides sufficient radiation shielding but also provides sufficient structural integrity to be considered as a spacecraft material. This presentation will discuss the deep space radiation problem and the material based solutions being proposed by BAE SYS scientists to overcome this problem. The presentation will focus on the initiative taken by BAE SYS scientists to proactively engage and team with experts at NASA, small business, and other federal laboratories to develop and test a dual phase composite material. The presentation will also highlight the potential benefits to our customer, NASA and also to BAE SYS.
ISO-26262, the road vehicle functional safety standard, underwent a major overhaul that was released in December 2018. Radiation effects, and single-event effect (SEE) hazards in particular, play an important role in autonomous vehicle safety. This connection will only increase as the level of driving automation goes from "hands off," to "eyes off," to "mind off." This translates to increased coupling with space climate and weather in addition to other traditional terrestrial radiation sources like thorium and uranium contamination in process and packaging materials. We will focus on autonomous vehicle radiation effects and present both benefits and challenges to the space weather and radiation engineering communities.
With recent advances in solid state imaging technology and the increasing availability of synchrotron x-ray radiation sources, synchrotron x-ray microtomography is emerging as a nondestructive technique for the evaluation of the structure and composition of small specimens with spatial resolution in the micron range. Synchrotron radiation offers the following advantages over conventional x-ray sources: high brightness, continuous emission which is tunable over a large energy range, faster data collection rates, and a highly collimated beam of large cross section permitting the illumination of large specimens. Synchrotron x-ray microtomography enables the structure of individual spheres to be evaluated in order to reveal the concentricity and sphericity of the internal void and the uniformity of the shell wall in the case of high quality spherical shells for Sandia National Laboratories' Inertial Confinement Fusion project.
If a collision of two large, massive, fast gas clouds occurs, their kinetic energy is converted to radiation in a pair of shock fronts at their interface. The resulting structure is described, and the relevance of this as a radiation source for quasi-stellar objects is considered.
The Long Duration Exposure Facility (LDEF) satellite was recovered after almost six years in space. It was well-instrumented with ionizing radiation dosimeters, including thermoluminescent dosimeters, plastic nuclear track detectors, and a variety of metal foil samples for measuring nuclear activation products. The extensive LDEF radiation measurements provide the type of radiation environments and effects data needed to evaluate and help resolve uncertainties in present radiation models and calculational methods. A calculational program was established to aid in LDEF data interpretation and to utilize LDEF data for assessing the accuracy of current models. A summary of the calculational approach is presented. The purpose of the reported calculations is to obtain a general indication of: (1) the importance of different space radiation sources (trapped, galactic, and albedo protons, and albedo neutrons); (2) the importance of secondary particles; and (3) the spatial dependence of the radiation environments and effects expected within the spacecraft. The calculational method uses the High Energy Transport Code (HETC) to estimate the importance of different sources and secondary particles in terms of fluence, absorbed dose in tissue and silicon, and induced radioactivity as a function of depth in aluminum.