Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2002. / Cataloged from PDF version of thesis. / Includes bibliographical references (page 21). / The purpose of this thesis is to discuss the relationship between U.S. space policy and: 1) national technological prestige 2) military superiority 3) and ultimately the political competition between the United States and the Soviet Union. The paper will focus primarily on national and military prestige, while briefly touching on the price tag of the early space advancements. It will concentrate on the early days of space exploration. The thesis will examine the impact the Russian satellite, Sputnik, had on the American people and the reaction of the United States. The thesis will also look at the beginning of the Apollo program and the decision to send man to the Moon. In conclusion, the thesis will look at a possible future for the United States space program and analyze the decision of America's leaders to abandon ambitious endeavors since the Apollo Moon landing. / by Michael A. Barboza. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1987. / Includes bibliographies. / by Karen Jean Meech. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1985. / Microfiche copy available in Archives and Science. / Bibliography: leaves 166-170. / by Daniel Lewis Orange. / M.S.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 58-59). / The Acasta Gneiss Complex in Northwest Canada contains the oldest dated rocks in the world. The gneisses range in age from 4.03-3.6 Ga, as determined by U-Pb dating of zircons (Bowring and Williams 1999). U-Pb dating of xenocrystic cores in these zircons indicates a cryptic record of continental crust older than 4.0 Ga. In this study, zircons were selected and characterized from thirteen samples of Acasta Gneisses. Many of the zircons contain xenocrystic cores mantled by younger domains. U-Pb geochronological data were collected using laser ablation inductively coupled plasma mass spectrometery (LA-ICPMS). Twelve of the samples show evidence for two distinct crystallization events, one which formed the cores and another in which the mantle domain overgrew the cores. The oldest cores were dated at >4.0 Ga. This provides additional evidence for pre-4.0 Ga crust formation in the late Hadean. / by Roxana G. Safipour. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, February 2011. / Cataloged from PDF version of thesis. "December 20, 2010." "This thesis was submitted to the Institute Archives without all the required signatures"--Disclaimer Notice page. / Includes bibliographical references (pages 33-34). / This paper seeks to describe an impact glass from the K/T boundary layer at Beloc that is depleted in rare earth elements (REE) relative to continental crust. It is widely agreed that a large bolide struck the Yucatan Peninsula roughly 65 Ma spreading a worldwide iridium anomaly. However, there is only one case of a piece of the impactor being found (Kyte et al., 1995). Impact glass from the K/T boundary at Beloc, Haiti has been widely researched with several types of glass documented. So far, all of the documented glass exhibits a crustal REE compositional pattern. In this study, REE composition from two glass types from the same K/T boundary layer sample are examined using a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS). One glass type exhibits crustal REE composition which is enriched normalized to chondrite. The other glass type, however, displays a meteoritic REE composition signature. REE patterns for this glass are nearly flat when plotted normalized to chondrite with an average La/Sm ratio of 1.51 compared to 2.69 for crustal glass. Major element data were obtained through electron microprobe analysis and displays a composition that differs from one glass type to the other. Results suggest chondritic parent material from the Chicxulub impactor. / by Dennis W. Fantone. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2006. / Includes bibliographical references (leaves 173-177). / The instruments used to measure borehole acoustic data can be classified as either wireline or logging while drilling (LWD). The wireline tool measures formation speeds after the borehole is drilled, and the LWD tool measures formation speeds while the borehole is drilled. This thesis focuses on comparing the data collected by these tools and how formation properties affect their measurements. LWD and wireline measurements taken from the same borehole are compared. Discrepancies in estimated shear and compressional velocities, as calculated by time semblance methods, were found between the two data sets. We modeled radially layered formations with increasing or decreasing radial velocity profile to estimate the acoustic measurement penetration for each tool. We reprocessed sections of the data using frequency semblance methods and compared with layered model results. We found that a frequency-domain analysis is feasible and reduces the overall difference between the LWD and wireline shear and compressional velocity estimates. The remaining discrepancy can be explained by the different radial depths of penetration of these two tools, which naturally leads to a difference in the velocity estimates when there is a radial gradient in the velocity profile. / (cont.) We model axisymmetric propagation of waves in a borehole with a transversely isotropic (TI) formation. An algorithm is developed for an arbitrarily radially layered medium that can be used to approximate the steel LWD tool inside the fluid-filled borehole. We present a full description of modal arrivals, as a function of frequency and phase velocity, for the LWD tool and compare with the wireline case, both for isotropic and TI formation. The tool modes were found to be largely unaffected by the presence of a TI medium while the modes associated with the borehole fluid and formation, i.e. Stoneley, pseudo-Rayleigh and borehole flexural modes, displayed sensitivity to the TI formation parameters, specifically to C44 in the elastic stiffness matrix. Our analysis demonstrates that at a lower frequency of operation, the LWD tool can potentially measure the effect of a TI medium in the fundamental shear modes, if the modes are well-coupled to the formation (i.e., the formation is soft). This thesis makes two new contributions to the field of borehole geophysics. Firstly, we make an independent comparison of LWD and wireline measurements, and our work suggests that frequency-domain semblance processing may be a better method of analysis, particularly in radially varying formations. / (cont.) As industry moves toward faster and more cost efficient LWD measurements, it is essential to understand the implications of the LWD tool geometry in relation to its wireline counterpart and how traditional velocity processing methods are affected. Secondly, we present a modal analysis of the LWD tool in a transversely isotopic formation, which suggests that the newer generation of LWD tools, operating in a lower range of frequency may be able to measure TI formations. The TI medium is of major importance to exploration geophysics as it represents the anisotropy found in thinly layered media, i.e. sedimentary strata. This is the predominant form of anisotropy seen in many sedimentary basins, so that its effect on LWD measurements is of great interest to exploration geophysics. / by Victoria Alice Briggs. / Ph.D.

Thesis: S.M. in Climate Physics and Chemistry, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 81-83). / This thesis works to evaluate the new rainfall algorithm that is used to simulate longterm tropical cyclone precipitation (TCP) climatology throughout the southeastern United States. The TCP climatology is based on a fleet of synthetic tropical cyclones developed using National Center for Atmospheric Research/National Centers for Environmental Prediction reanalysis data from 1980 to 2010 and the Coupled Hurricane Intensity Prediction System (CHIPS) model. The climatology is compared to hourly rainfall estimates from the WSR-88D Next Generation Weather Radar (NEXRAD-II) system. In general the synthetic TCP estimates show good agreement with radar-based observations. The rainfall algorithm appears to perform better at coastal locations versus inland ones, and in general has better agreement in the eastern locations considered in this study. In addition, the spatial dependence of radar rainfall estimates was addressed, and in general more extreme TCP-events exhibited a greater degree of event total precipitation variation at grid box-scale. Finally, preliminary work incorporating streamflow measurements as a metric for assessing TCP risk using the synthetic rainfall climatology was begun. Correlation between both grid box-specific and basin-average radar-based event TCP and surface streamflow measurements (from the U.S. Geological Survey National Water Information System) varied greatly, and was generally moderate, and future work should incorporate more thorough streamflow modeling in order to evaluate these comparisons. / by Sandra Michael Shedd. / S.M. in Climate Physics and Chemistry

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1984. / Microfiche copy available in Archives and Science. / Includes bibliographical references. / by David Michael Sherman. / Ph.D.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 169-177). / The recorded seismic signal contains full information about the source that generated the seismic waves and the path along which the seismic waves travel and interfere with subsurface. However, source information is not an explicit part of the seismic record and thus is a large source of uncertainty in seismic imaging and velocity analysis applications. In this thesis, we develop source-independent methods for seismic imaging, seismic trace interpolation and velocity analysis using the interference between pure (PP and SS) and converted-phase (PS and SP) waves. For seismic imaging, we develop amplitude-balancing source-independent converted-phase seismic imaging conditions and introduce a concept of conversion ratio coefficients to provide a physical and mathematical foundation for source-independent converted-phase (SICP) imaging. For seismic trace interpolation, we develop a scheme for migration/de-migration to suppress migration-based artifacts due to sparse station deployments. For velocity analysis, we present first a source-independent space-lag domain Extended SICP imaging condition (ESICP-IC). Then, we mathematically derive an optimization scheme for source independent converted-phase wave equation migration velocity analysis (SICP-WEMVA). We investigate numerically the stability and convergence of SICP-ICs, SICP interpolation and SICP-WEMVA with synthetic data. Finally, using the developed methodologies, we investigate the subsurface structure of the Hengill geothermal area in Iceland using the abundant micro-seismic activity of the region. The constructed SICP seismic images show detailed subsurface structure of the Hengill area that is well correlated with previous seismic and resistivity studies. Also, we find that the amplitudes of the images are well correlated with a low resistivity region of the geothermal area. The reason for this correlation is not fully understood, but may provide an additional tool for investigation of the Hengill site. / by Andrey Hanan Shabelansky. / Ph. D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 161-169). / The currently observed increase in atmospheric CO2 due anthropogenic emissions is substantially slowed by natural processes that incorporate CO2 into the terrestrial biota and the ocean. Year-to-year changes in the CO2 growth rate that exceed variations in the fossil fuel source indicate a significant variability in these global CO2 sinks. However, the enormous complexity of the terrestrial and oceanic biogeochemical systems that absorb atmospheric CO2 makes these sinks extremely difficult to understand and precisely quantify. Many techniques, including the interpretation of the relative changes in atmospheric CO2 and O2/N2, ocean modeling, and atmospheric data inversions, have been employed to estimate the mean and variability of global CO2 sinks. However, uncertainty remains large. The goal of this thesis is to improve understanding of global CO2 sinks by considering (1) the error in the atmospheric O2/N2 partitioning method due to the neglect of interannual variability in the air-sea fluxes of 02, and (2) the interannual variability of the ocean CO2 sink. / (cont.) A global, high-resolution ocean general circulation model is used to estimate the magnitude and understand the mechanisms of interannual variability in air-sea fluxes of both CO2 and 02. I find that the global variability in the fluxes of both gases are dominantly forced by large-scale physical processes governing upper ocean dynamics, particularly El Nifio / Southern Oscillation (ENSO) and, for 02, the North Atlantic Oscillation (NAO). Estimates of the extremes of CO2 and 02 flux variability for the period 1980-1998 are +/-0.5x1015 grams Carbon/yr (PgC/yr) and -70/+100x1012 mol/yr (Tmol/yr), respectively. Global 02 flux variability implies up to a 1.0 PgC/yr error in estimates of interannual variability in land and ocean CO2 sinks derived from atmospheric 02/N2 observations. This error is significant for estimates of annual sinks, but it is cumulatively negligible for estimates of mean sinks from October 1991 to April 1998. Increasing convergence of estimates of land. / by Galen Anile McKinley. / Ph.D.