Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2007. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 49-50). / Stabe isotope probe (SIP) incubation studies were performed using ¹³C-labeled carbon substrates on hyperthermophilic filamentous streamer communities inhabiting Octopus Spring in Yellowstone National Park. Biomass was removed from the outflow stream and incubated at near-in situ conditions with labeled bicarbonate, formate, or acetate. Lipids from the biomass were extracted and analyzed using gas chromatography-mass spectroscopy (GC-MS) and gas chromatography-isotope ratio monitoring-mass spectroscopy(GC-IRMS). We observed incorporation of ¹³C-labeled acetate into the total biomass, archaeal lipids, and a small number of bacterial lipids, but no incorporation of labeled formate or bicarbonate. During 67 hours of incubation, 0.060 [mu]g of labeled acetate was incorporated by the archaeal and bacterial community. The lack of acetate incorporation by most bacteria, or formate and bicarbonate incorporation by any community member may reflect rates of carbon turnover, the carbon acquisition pathway used, or inhibition under experimental conditions, / by Augusta K. Dibbell. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2003. / Cataloged from PDF version of thesis. In title on title page, "[alpha] appears as lower case Greek letter. "May 21, 2003." / Includes bibliographical references (page 31). / We present results from observations of H107[alpha] recombination-line emission and the related 4800 MHz continuum emission of the HII region RCW 38 using the Australia Telescope Compact Array. We find the continuum emission to be concentrated in a ring-like structure with the 05 star, IRS2, approximately centered in the cavity within the ring. The temperature of the ionized gas ranges from 5200 to 7500 K and the emission is optically thin. The H107[alpha] line emission appears to be confined within the continuum ring. We also find the continuum ring to encircle the peak in the diffuse X-ray gas. The radio continuum emission matches closely to NIR observations with a bright western ridge containing the peak in the 10[mu]m emission known as IRS1 (Frogel et al. 1974) apparent in both observations. From calculations of continuum and line parameters, we estimate the spectral type of the ionizing source for the region to be an 05/06 star which is consistent with the spectral type of IRS2. / by Miquela Vigil. / S.B.

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 25-30). / Sahara 99555 (SAH 99555) is the oldest dated angrite sample, a rare type of meteorite, and is only ~2 Myr younger than the age of the solar system (1, 2). SAH 99555 shows no post-cooling brecciation or weathering from the parent body, and does not display signs of significant terrestrial weathering. Therefore, paleomagnetic experiments were conducted for the first time on SAH 99555 to discover if it contains a primary paleomagnetism and then to determine a paleointensity estimate and its ferromagnetic mineralogy. Our studies show that the primary ferromagnetic mineral in SAH 99555 is magnetite and there are also some accessory ferromagnetic minerals including titanomagnetite and hematite. The natural remanent magnetization (NRM) of SAH 99555 appears to have a low-coercivity component probably from a collector's hand magnet or the Earth's field as well as a high-coercivity component, similar to D'Orbigny, another angrite. The paleointensity measurements of the high-coercivity component of SAH 99555,5 agree with the paleointensity estimates made for other angrites (D'Orbigny and A-881371) by Weiss et al. (2008) (4). Therefore, it appears that SAH 99555 does record a primary paleofield from when it was on the angrite parent body, which would be the oldest known paleomagnetic record yet identified in a planetary rock. Further studies are suggested to verify these conclusions, which make SAH 99555 one more key data point in the understanding of the early solar system. / by Sarah P. Slotznick. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991. / Includes bibliographical references. / by Randall Lee Mackie. / Ph.D.

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.