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31.
    
The overall objective of this experiment is exploratory reconnaissance of Jupiter, Saturn, their satellites, and Saturn's rings. Such reconnaissance, at resolutions and phase angles unobtainable from Earth, can be expected to provide much new data relevant to the atmospheric and/or surface properties of these bodies. The experiment also has the following specific objectives:Observe and characterize the global circulation of the atmospheres of Jupiter and Saturn;Determine the horizontal and vertical structure of the visible clouds and establish their relationship to the belted appearance and dynamical properties of the planetary atmospheres;Determine the vertical structure of high, optically-thin, scattering layers on Jupiter and Saturn;Determine the nature of anomalous features such as the Great Red Spot, South Equatorial Belt disturbances, etc.;Characterize the nature of the colored material in the clouds of Jupiter and Saturn, and identify the nature and sources of chromophores on Io and Titan;Perform comparative geologic studies of many satellites at less than 15-km resolution;Map and characterize the geologic structure of several satellites at high resolution (1 km);Investigate the existence and nature of atmospheres on the satellites;Determine the mass, size, and shape of many of the satellites by direct measurement;Determine the direction of the spin axes and periods of rotation of several satellites, and establish coordinate systems for the larger satellites;Map the radial distribution of material in Saturn's rings at high resolution;Determine the optical scattering properties of the primaries, rings, and satellites at several wavelengths and phase angles;Search for novel physical phenomena, e.g., phenomena associated with the Io flux tube, meteors, aurorae, lightning, or satellite shadows.Team leader.Deputy team leader.  相似文献   
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We have explored the direct and indirect radiative effects on climate of organic particles likely to have been present on early Earth by measuring their hygroscopicity and cloud nucleating ability. The early Earth analog aerosol particles were generated via ultraviolet photolysis of an early Earth analog gas mixture, which was designed to mimic possible atmospheric conditions before the rise of oxygen. An analog aerosol for the present-day atmosphere of Saturn's moon Titan was tested for comparison. We exposed the early Earth aerosol to a range of relative humidities (RHs). Water uptake onto the aerosol was observed to occur over the entire RH range tested (RH=80-87%). To translate our measurements of hygroscopicity over a specific range of RHs into their water uptake ability at any RH < 100% and into their ability to act as cloud condensation nuclei (CCN) at RH > 100%, we relied on the hygroscopicity parameter κ, developed by Petters and Kreidenweis. We retrieved κ=0.22?±0.12 for the early Earth aerosol, which indicates that the humidified aerosol (RH < 100 %) could have contributed to a larger antigreenhouse effect on the early Earth atmosphere than previously modeled with dry aerosol. Such effects would have been of significance in regions where the humidity was larger than 50%, because such high humidities are needed for significant amounts of water to be on the aerosol. Additionally, Earth organic aerosol particles could have activated into CCN at reasonable-and even low-water-vapor supersaturations (RH > 100%). In regions where the haze was dominant, it is expected that low particle concentrations, once activated into cloud droplets, would have created short-lived, optically thin clouds. Such clouds, if predominant on early Earth, would have had a lower albedo than clouds today, thereby warming the planet relative to current-day clouds.  相似文献   
33.
It recently has been shown in the literature that many dc-to-squarewave parallel inverters which are widely used in power-conditioning applications can be grouped into one of two families. Each family is characterized by an equivalent RLC network. Based on this approach, a classification procedure is presented for self-oscillating parallel inverters which makes evident natural relationships which exist between various inverter configurations. By utilizing concepts from the basic theory of negative resistance oscillators and the principle of duality as applied to nonlinear networks, a chain of relationships is established which enables a methodical transfer of knowledge gained about one family of inverters to any of the other families in the classification array.  相似文献   
34.
The predominance of nitrogen in highly volatile forms and of carbon in solids set the abundance ratios of these elements in the inner planets, meteorites and comets. The absence of carbon compounds in an atmosphere then signals large deposits of carbon-bearing compounds in surface and/or subsurface deposits. In contrast, the icy planetesimals that contributed heavy elements to Jupiter must have had identical enrichments (relative to hydrogen) of both C and N, as well as other heavy elements that have been measured, compared to solar values. Capture of N and Ar suggests that the icy planetesimals that carried these elements must have formed at low temperatures, <40 K. New measurements of isotopes of nitrogen support this picture, but we must have more measurements in more atmospheres to be certain of this scenario.  相似文献   
35.
The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm− 1 (1 mm to 7μ m), with a spectral resolution that can be set from 0.5 to 15.5 cm− 1. The far infrared portion of the spectrum (10–600 cm− 1) is measured with a polarizing interferometer having thermopile detectors with a common 4-mrad field of view (FOV). The middle infrared portion is measured with a traditional Michelson interferometer having two focal planes (600–1100 cm− 1, 1100–1400 cm− 1). Each focal plane is composed of a 1× 10 array of HgCdTe detectors, each detector having a 0.3-mrad FOV. CIRS observations will provide three-dimensional maps of temperature, gas composition, and aerosols/condensates of the atmospheres of Titan and Saturn with good vertical and horizontal resolution, from deep in their tropospheres to high in their mesospheres. CIRS’s ability to observe atmospheres in the limb-viewing mode (in addition to nadir) offers the opportunity to provide accurate and highly resolved vertical profiles of these atmospheric variables. The ability to observe with high-spectral resolution should facilitate the identification of new constituents. CIRS will also map the thermal and compositional properties of the surfaces of Saturn’s icy satellites. It will similarly map Saturn’s rings, characterizing their dynamical and spatial structure and constraining theories of their formation and evolution. The combination of broad spectral range, programmable spectral resolution, the small detector fields of view, and an orbiting spacecraft platform will allow CIRS to observe the Saturnian system in the thermal infrared at a level of detail not previously achieved.This revised version was published online in July 2005 with a corrected cover date.  相似文献   
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We summarize the current status of atmospheric chemistry in the atmospheres of the outer solar system with special emphasis on the question of HCN formation on Jupiter, differences between polar and equatorial compositions on Jupiter, the coloration of the Great Red Spot, and the unique environment of Titan.  相似文献   
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39.
A new procedure for the selection of magnetic cores for use in energy-storage dc-to-dc power converters that eliminates the need for an automated computer search algorithm and stored data file is presented. The converter configurations included in the procedure are the three commonly encountered single-winding converters for voltage stepup, for current stepup and voltage stepup/current stepup, and for the two-winding converter for voltage stepup/current stepup. For each converter configuration, three types of controllers are considered: constant-frequency, constant on-time, and constant off-time. Using concepts developed from analyses of these converters by considering the transfer of energy by means of an energystorage inductor or transformer, a special table of parameters calculated from magnetic core data is constructed, which leads to a considerably simplified design procedure.  相似文献   
40.
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