No description available.

Thesis (Ph.D.)--Universität Berlin, 2005. / Includes bibliographical references.

Thesis (Ph. D.)--California Institute of Technology, 1976. / Includes bibliographical references.

Existing martian relative age chronologies rely entirely or predominantly on Mariner 9 images, extrapolated numbers of craters, and craters 500(DEGREES)K) for the planet are consistent with the derived chronology.

Numerous wave and gap features observed in Voyager data of Saturn's rings are produced by resonances between the orbital frequencies of known external satellites and ring particle orbits. This thesis investigates the possibility that other, currently unassociated, ring features are generated by perturbations on ring participle orbits produced by non-axisymmetric gravitational fields resulting from acoustic oscillation modes of the planet. The frequencies of Saturnian low degree (l ≤ 8) fundamental (or f) mode oscillations are calculated for a variety of Saturn interior models which span the range of uncertainty of the interior structure of the planet. Corrections for rotation, oblateness, and possible differential rotation have been applied. Only the low degree f-modes are found to have frequencies and likely wave amplitudes in the range necessary to produce gap or wave features in the rings. The calculated positions of outer Lindblad resonances (OLR) for the degree l = 2,3,4, and 5 sectoral f-modes of a single Saturn model lie near four previously unassociated C-ring features. These features are the Maxwell gap and three waves identified as being forced at either OLR or inner vertical resonances. The outer vertical resonance (OVR) of the l = 5, m = 4 mode also overlaps the location of a wave which may be forced at either an OVR or an inner Lindblad resonance. Four other similar wave features, however, cannot be explained by oscillation mode resonances. This failure to account for all of the comparable unassociated C-ring waves is the principal inadequacy of the hypothesis. Other observed properties of the wave features, however, including their azimuthal wavenumbers m and the variation of amplitude with proposed oscillation mode degree are consistent with the proposed forcing. Planetary oscillation amplitudes of ∼1 m are required for gap opening; wave amplitudes of ∼10 cm are required for density wave production. The C-ring thus serves as a very sensitive f-mode detector. Observations by the Cassini spacecraft should unequivocally determine if the C-ring features are produced by planetary oscillation modes. If these observations confirm the association, significant new constraints could be placed on Saturnian energy transport, differential rotation, and core size.

Inaug.-Diss.--Kaiser Wilhelms Universität. / Includes bibliographical references.

published_or_final_version / Earth Sciences / Master / Master of Philosophy

An observational program was carried out to investigate the spectrum of Pluto at various points on its lightcurve. Spectrophotometry of Pluto in the wavelength range of 5600 to 10500 Å was obtained on four nights covering lightcurve phases of 0.18, 0.35, 0.49, and 0.98. The four phases included minimum light (0.98) and one near maximum light (0.49). The spectra reveal variations in the adsorption depths of the methane bands at 6200, 7200, 7900, 8400, 8600, 8900, and 10000 Å. The minimum amount of adsorption was found to occur at minimum light. A model for the surface and atmosphere of Pluto was constructed in an attempt to explain the phase variation observed. The model is based upon a previous photometric two-spot model which was constructed to explain the variations in the lightcurve from 1950 to 1982. Two dark circular spots (46° and 28° in radius, both at latitude -23°, separated by 134° in longitude) were used to constrain the surface distribution of methane frost on the surface of Pluto. The reflectance properties of the two terrains were modelled with a theory by B. Hapke (J.G.R., v. 86, p. 3039, 1981) which includes the effects of multiple scattering in the surface frost. The particle size and continuum optical depth of the frost particles were allowed to vary between the dark regions inside the spot boundaries and the brighter regions surrounding the spots. The transmission of the atmosphere was calculated using the Mayer-Goody band model. The model fit to the spectrum required the presence of a frost with particle sizes on the order of 1-20 mm in order to explain the observed phase dependence of the methane bands. Using only the atmosphere and no surface frost implies a variation in column abundance of 30% within three days. From energy balance considerations this variation in column abundance is not possible. By including the absorption of methane frost on the surface a range of model solutions was obtained. This range yields an approximate limit of 5.5 m-amagats to the amount of gas that can be present and still achieve a good fit to the phase variation of the 7200 Å band. If the atmosphere is removed from the model an equally good fit to the 7200 Å band is obtained. A major problem with the model is its failure to reproduce the relative absorption band depths. The gaseous atmospheric calculation on the other hand can fit the spectrum quite well. Possible explanations include a particle size distribution within a given terrain.

No description available.

Thesis (Ph.D.)--York University, 2005. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 113-120). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR11603