Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995. / Includes bibliographical references (p. 157-158). / by David Car. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1994. / Includes bibliographical references (leaves 127-129). / by Gregory Scott McNulty. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997. / Includes bibliographical references (leaves 166-170). / by Luc G. Fréchette. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1989. / Includes bibliographical references (leaves 81-82). / by Nicolas R. Goulet. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1989. / Includes bibliographical references (leaves 124-126). / by John Joseph Blandino. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005. / 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. 179-182). / In this thesis, I present neutral atmosphere, ionosphere and total delays experienced by GPS signals traveling to space vehicles during launch, orbit and reentry. I calculate these delays for receivers at 0 km to 1700 km altitude by ray-tracing through the Global Reference Atmosphere Model (1999) and the International Reference Ionosphere (2001). These delays are potentially much larger than those experienced by signals traveling to GPS receivers near the surface of the Earth, but are primarily experienced at negative elevation angles, and are therefore most relevant for space vehicles with limited visibility of GPS satellites and during launch and reentry. I compare these signal delays to the delays predicted by three onboard delay models: the Altshuler and NATO neutral atmosphere delay models, and the Klobuchar ionosphere delay model. I find that these models are inadequate when the space vehicle is in orbit. The NATO model will suffice during the final period of reentry, where it predicts the neutral atmosphere delay to within 1 m of the ray-traced value, but it will not suffice when a satellite is rising or setting. I propose a method to extend the NATO model for receivers at higher altitudes. The Klobuchar model will suffice for most satellites during reentry, but will potentially predict ionosphere delays with errors up to 30 m, and will not suffice when a satellite is rising or setting. / by Rachel Neville Thessin. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 56-63). / Alternative fuels have the potential to mitigate transportation's impact on the environment and enhance energy security. In this work, we investigate two alternative fuels: liquefied natural gas (LNG) as an aviation fuel, and middle distillate fuel derived from woody biomass for use in aviation or road transport. The use of LNG as a supplemental aircraft fuel is considered in the context of the Lockheed Martin C- 1 30H and C-130J transport aircraft. We estimate the cost of retrofitting these aircraft to use LNG and the savings from reduced fuel expenses. We evaluate the societal impacts of LNG within a cost-benefit framework, taking into account resource consumption, human health impacts related to air quality, and climate damage. We find that aircraft operators can save up to 14% on fuel expenses (retrofit costs included) by employing LNG retrofits, with a 95% confidence interval of 2-23%. Society can also benefit by 12% (3-20%) from LNG use as a result of improved surface air quality, lower resource consumption, and climate neutrality relative to conventional fuel. These results are highly dependent on fuel prices, the quantity and cost of the LNG retrofits, and the frequency and length of missions. Woody biomass harvested from old-growth forests produces a large carbon debt when used as a feedstock for transportation fuel. Managed forests are an attractive alternative for inexpensive biomass production with the potential to reduce this carbon debt. We study the effect of forest management practices on the carbon debt payback time resulting from harvesting woody biomass from managed forests for middle distillate fuel production. We also calculate the breakeven time in terms of radiative forcing, temperature change, and economic damages. We find that biofuels produced over a period of 30 years have higher CO 2 emissions than fossil fuels for 59 years, higher radiative forcing for 42 years, higher temperature change for 48 years, and higher cumulative discounted (1-2%) economic damages for more than 100 years. These damages never break even at discount rates above 2%. Payback times can be reduced by increasing the age at which biomass is harvested. When biofuel production is sustained indefinitely, greater climate benefits are achieved over the next 100 years by instead producing long-lived wood products like lumber. / by Mitch Russell Withers. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005. / Includes bibliographical references (p. 127-131). / The new solar system exploration objectives announced in January 2004 have the goal of sending humans back to the Moon by the year 2020 in preparation for human exploration of Mars. Advanced, but cost effective, surface navigation and communication capabilities are required to support these new exploration objectives. In response to this need, a set of three Navigation/Communication architectures have been designed: Minimalist, Simple, and Performance, as well as several augmentation options. The design and refinement of these architectures was performed using numerous models and tools developed for this work. A unique feature of the analysis in this thesis was that the architectures considered combine different navigation assets (onboard, on-surface and on-orbit). The three main Navigation/Communication architectures were then evaluated and compared using several metrics, such as navigation coverage, accuracy and operability, communication metrics, and mass. Based on this analysis we recommend the initial deployment of the Simple architecture for surface exploration of the Moon and Mars with a gradual accretion of assets and possibly transition to the Performance architecture. A specific combination of onboard and vision-based sensors is recommended as the fundamental navigation equipment. In addition to this navigation study, a control-based analysis of formation flying dynamic models around the libration point L₂ of the Sun-Earth system is also presented. The objective of this research was to assess the quality of different dynamical models of the relative motion of two spacecraft in orbit around Sun-Earth L₂. / (cont.) This was done using open-loop simulations to investigate the intrinsic fidelity of each model and closed-loop simulations to evaluate the impact of modeling errors on fuel costs. The conclusion from this analysis is that the more sophisticated models give appreciable better closed-loop performance, and that the difference appears to be sufficient to justify the additional effort required to implement them on-line. / by Thomas Chabot. / S.M.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1940. / Microfiche copy available in Barker. MIT copy bound with: Characteristics of gasoline-alcohol blends / Edgardo N. Accinelli. 1940. / by Paul M. Butman. / B.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001. / Includes bibliographical references (p. 99-100). / by Samuel A. Schweighart. / S.M.