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This slide presentation reviews a method for planet finding using microelectromechanical systems (MEMS) Adaptive Optics (AO). The use of a deformable mirror (DM) is described as a part of the instrument that was designed with a nulling interferometer. The strategy that is used is described in detail.
We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array images at A = 7 mm with approx.0.15 milliarcsec resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long timescales (months/ years), but the correspondence is poorer on shorter timescales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.
The Autonomy Operating System (AOS) is a software system that enables core capabilities for the autonomous operations for an unmanned aircraft. It is based on the NASA cFS system and provides a higher-level layer of infrastructure and applications for the execution of flight plans, natural-language communication with Air Traffic Control, Diagnostics, Prognostics, and contingency planning.
In this talk we present an overview of NASA's Atmosphere Observing System (AOS) mission, including plans for making use of object tracking.
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It is noted that 11 high-resolution spectra in the far-ultraviolet and two high-resolution spectra in the mid-ultraviolet were obtained. A high-velocity stellar wind exists as indicated by narrow shortward-displaced absorption features superposed on the P Cygni lines of N V, Si IV, and C IV. Absorption lines caused by N IV and C III are present and show nonorbital velocities of about -50 to -150 km/sec. Several weak photospheric lines of the primary star are detected. A few lines of Fe IV and Fe V are detectable near phase 0.50 and, less prominently, near phase 0.00. It is noted that the He II absorption line appears doubled except near phases 0.00 and 0.50 and that the weaker component appears to be attributable to the secondary component of the system. The mean velocity of the stellar wind is -1879 + or - 51(p.e.) km/sec and is nearly constant over the period of observation, although the absorption strength is found to vary.
The high-redshift blazar A0 0235 + 164 exhibits flux-density variations which are primarily of the less common variety in which low-frequency flux-density variations track the high-frequency variations but are delayed and of smaller amplitude. Observational results based on five years of monitoring are presented which are correlated over at least a factor of 50 frequency range in the sense expected for an expanding synchrotron component: outbursts propagating toward lower frequencies with diminishing amplitudes. A simple, semiempirical jet model is developed which accounts reasonably well for the radio properties of the object. The predictions of the model are compared with observations, examining the radio flux-density histories, the radio spectral evolution, the radio structure, and evidence for relativistic bulk motion.
The experiment A0 138-6 was located on the trailing edge of LDEF as part of the Experiment FRECOPA. Material specimens 2 x 2 cm, independently mounted in sample-holders with their surface in the same reference plane, were exposed to space. Materials include paints (conductive or not), SSMs, polymeric films, surface coatings, composite materials, and metals. The results show that for some materials the degradation was higher for samples in the canister than for those directly mounted on the tray; contamination problems were ruled out, the higher temperature experienced by the samples inside the canister probably explains this phenomenon.
The results are presented of experiments located in one of FRECOPA canister on epoxy-matrix carbon fiber reinforced composite materials, adhesives, and thermal coatings. Only thermal coatings and some composite materials were exposed to direct space environment for the first year, while other materials (for mechanical and expansion tests) were located in the lower levels (subjected to only vacuum and thermal cycling). In order to assess the degradation of materials after space aging, reference specimens were stored in clean room for the duration of LDEF mission and tested at the same time as the aged specimens.
The experiment objectives are: to detect a variation of the coefficient of thermal expansion (CTE) of composite samples; to detect an evolution of mechanical properties; to compare the behavior of two epoxy resins. The CTE is measured by interferometric method in a vacuum chamber. The following mechanical tests are achieved on the samples: interlaminar shear strength; flexural strength; flatwise tensile strength. The results are reported.
The aim of this experiment was to test the optical behavior of 20 components and coatings subjected to space exposure. Most of them are commonly used for their reflective or transmittive properties in spaceborne optics. They consist in several kind of metallic and dielectric mirrors designed for the 0.12 to 10 microns spectrum, UV, and NIR bandpass filters, visible, and IR antireflecting coatings, visible/IR dichroic beam splitters, and visible beam splitter. The coatings were deposited on various substrates such as glasses, germanium, magnesium fluoride, quartz, zinc selenide, and kanigened aluminum. Several coating materials were used such as Al, Ag, Au, MgF2, LaF3, ThF3, ThF4, SiO2, TiO2, ZrO2, Al2O3, MgO, Ge, and ZnSe. Five samples of each component were manufactured. Two flight samples were mounted in such a way that one was directly exposed to space and the other looking backwards. The same arrangement was used for the spare samples stored on ground in a box identical to the flight one and they were kept under vacuum during the LDEF mission. Finally, one set of reference components was stocked in a sealed box under a dry nitrogen atmosphere. By comparing the preflight and postflight optical performances of the five samples of each component, it is possible to detect the degradations due to the space exposure.
Experiments on the the Long Duration Exposure Facility involving the study of the behavior of diffraction gratings, ruled replica, holographic, and ion etched masters with a long exposure to the space environment are discussed. To separate the metallic coatings compartment, some mirrors were added to the experiment. In order to be free from grating senescence on ground, one set of reference compounds was stored. Two sets of compounds were loaded, exposed, and shaded typed, in order to differentiate vacuum influences and sun illumination, cosmic dust, and radiation incidences. The investigation of possible damages was operated according to the fundamental triple point of view of wavefront flatness, absolute efficiency, and stray light level.
The Passive Exposure of Earth Radiation Budget Experiment Components (PEERBEC) experiment of the Long Duration Exposure Facility (LDEF) mission was composed of sensors and components associated with the measurement of the earth radiation budget (ERB) from satellites. These components included the flight spare sensors from the ERB experiment which operated on Nimbus 6 and 7 satellites. The experiment components and materials as well as the pertinent background and ancillary information necessary for the understanding of the intended mission and the results are described. The extent and timing of the LDEF mission brought the exposure from solar minimum between cycles 21 and 22 through the solar maximum of cycle 22. The orbital decay, coupled with the events of solar maximum, caused the LDEF to be exposed to a broader range of space environmental effects than were anticipated. The mission spanned almost six years concurrent with the 12 year (to date) Nimbus 7 operations. Preliminary information is presented on the following: (1) the changes in transmittance experienced by the interference filters; (2) the results of retesting of the thermopile sensors, which appear to be relatively unaffected by the exposure; and (3) the results of the recalibration of the APEX cavity radiometer. The degradation and recovery of the filters of the Nimbus 7 ERB are also discussed relative to the apparent atomic oxygen cleaning which also applies to the LDEF.
The unexpected duration for the flight of the Long Duration Exposure Facility (LDEF) conducted CNES to create a special investigation group in order to analyze all the materials and systems which compose the French Cooperative Payload (FRECOPA) except the experiments especially prepared for the flight. The FRECOPA tray was on the trailing face (V-) of the LDEF and protected from the atomic oxygen flux during all the flight. However, the solar irradiation was very important with solar flux quite perpendicular to the experiment once an orbit. There was also a good vacuum environment. The objectives are to test the effects of the combined space environment on materials and components like: structure, thermal control coatings and blankets, electronic unit, motors, and mechanical fixtures. When the LDEF returned to Kennedy Space Center, a visual inspection showed the very good behavior of the materials used and it was noted that the three mechanisms to open and close the experiment canisters worked completely. Many impacts of micrometeoroids or space debris on the structure and on the thermal protections were observed. After FRECOPA was brought back to Toulouse, many tests were performed and include: working order tests, mechanical tests (tension), optical and electronic microscopy (SEM), surface analysis (ESCA, SIMS, RBS, AUGER, etc.), thermal analysis, pressure measurements, and gas analysis (outgassing tests). The results of these experiments are discussed.
The experiment was aimed at checking compatibility of the aluminum conductors with conventional conductors and contacts under different conditions of manufacturing (mechanical or magnetostrictive crimping) and storage in laboratory or in long-duration space environment. The electrical characteristics of connections built from nickel-plated conductors and glided copper contacts were noted to vary over the duration of the experiment. These variations are unrelated with the crimping or storage conditions or with metal pairing (nickel-plated aluminum/tinned or silver copper). Such evolutions, even slight, are detrimental to connection quality. The same observations hold for some like connections subjected to long-duration thermal cycles. Therefore, work on aluminum technology was reoriented toward a silver aluminum conductor/ golded aluminum contact solution. The first evaluation test performed according to this definition have yielded satisfactory results.
High dispersion ultrahigh signal to noise Reticon spectra of Vega were obtained with the coude spectrograph of the 1.2 m telescope. A mean signal to noise ratio of 2500 over the spectral region lambdas from 3825 to 5435 was achieved. Examination of the line profiles confirmed the presence of two different types of profiles which were previously seen in IIIaJ and lower signal to noise Reticon spectra. The profiles of the strong lines are essentially classical rotational profiles with enhanced wings which are slightly stronger than expected while those of weak lines are clearly flat-bottomed resulting in a trapezoidal appearance. A few possible theoretical explanations are presented.
The Microabrasion Foil Experiment comprises arrays of frames, each supporting two layers of closely spaced metallic foils and a back-stop plate. The arrays, deploying aluminum and brass foil ranging from 1.5 to some 30 microns were exposed for 5.78 years on NASA's LDEF at a mean altitude of 458 km. They were deployed on the North, South, East, West, and Space pointing faces; results presented comprise the perforation rates for each location as a function of foil thickness. Initial results refer primarily to aluminum of 5 microns thickness or greater. This penetration distribution, comprising 2,342 perforations in total, shows significantly differing characteristics for each detector face. The anisotropy confirms, incorporating the dynamics of particulate orbital mechanics, the dominance of incorporating extraterrestrial particulates penetrating thicknesses greater than 20 microns in Al foil, yielding fluxes compatible with hyperbolic geocentric velocities. For thinner foils, a disproportionate increase in flux of particles on the East, North, and South faces shows the presence of orbital particulates which exceed the extraterrestrial component perforation rate at 5 micron foil thickness by a factor of approx. 4.