• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 86
  • 24
  • 9
  • 8
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 180
  • 57
  • 53
  • 21
  • 18
  • 18
  • 17
  • 17
  • 14
  • 14
  • 13
  • 13
  • 12
  • 12
  • 12
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Dark Ages Lunar Interferometer : Deployment Rover - Suspension System and Transition Mecanism

Pasalic, Haris, Bernfort, Björn January 2014 (has links)
This thesis is a continuation of last year's work and it builds on earlier construction of a rover that will deploy an interferometer on the far side of the moon. The project is done in collaboration with (JPL) Jet Propulsion Laboratoryin Pasadena, California. Given the size of the mission, accuracy and time limit project has been split into several smaller projects. The areas that are the focus of this project are the suspension and the transition system. The transition system that is originated from the stage when the rover transforms from the transit mode to ready mode, and the suspension system, are in this thesis work presented by detailed conceptual design. The next step, not mentioned this thesis work, will be to perform aprimary structure design on the details. The project owner’s ultimate goal is to create a better understanding about the origins of the universe and its continual changing. This would give scientists an opportunity to study some of the most fundamental questions that are still are waiting for answers. Together with a group of energy engineers, Gustav Andersson and Emil Ericsson, we were caught by the very attractive project assignment, well aware that not many people get the chance or the opportunity to be involved or work with projects like this.
32

A value proposition for lunar architectures utilizing on-orbit propellant refueling

Young, James Jamy 20 January 2009 (has links)
In 2004, President Bush addressed the nation and presented NASA's new vision for space exploration. This vision included the completion of the International Space Station, the retirement of the Space Shuttle, the development of a new crew exploration vehicle, and the return of humans to the moon by 2020. NASA's Exploration Systems Architecture Study (ESAS) produced a transportation architecture for returning humans to the moon affordably and safely. This architecture requires the development of two new Shuttle-derived launch vehicles, an in-space transportation vehicle, a lunar descent and landing vehicle, and a crew exploration vehicle for human transportation. The development of an in-space propellant transfer capability could greatly improve the performance, cost, mission success, and mission extensibility of the overall lunar architecture, providing a more optimal solution for future exploration missions. The work done in this thesis will analyze how this new capability could affect the current NASA lunar architecture, and will outline the value proposition of propellant refueling to NASA. A value proposition for propellant refueling will be provided to establish why an architecture that utilizes propellant refueling is better equipped to meet the goals of the Vision for Space Exploration than the current baseline design. The primary goal addressed in this research is the development of a sustainable and affordable exploration program. The value proposition will outline various refueling strategies that can be used to improve each of the architecture Figures of Merit. These include a decrease in the Life Cycle Cost of both the lunar and Mars exploration campaigns, the ability to more than double the mission payload that can be delivered to the lunar surface during cargo missions, improving the probability of successfully completing each lunar mission, decreasing the uncertainty, and therefore risk, experienced during the development process, and improving the extensibility of the exploration architecture by utilizing a greater portion of the lunar program for future crewed mission. The ability to improve these Figures of Merit provides NASA with a more valuable architecture because NASA is able to achieve a greater return on its large initial investment.
33

Picturing knowledge : NASA's Pioneer plaque, Voyager record and the history of interstellar communication, 1957-1977

Macauley, William January 2010 (has links)
In the late twentieth century, science and technology facilitated exploration beyond the Solar System and extended human knowledge through messages comprised of pictures and mathematical symbols, transmitted from radio telescopes and inscribed on material artifacts attached to spacecraft. ‘Interstellar communication’ refers to collective efforts by scientists and co-workers to detect and transmit intelligible messages between humans and supposed extraterrestrial intelligence in remote star systems. Interstellar messages are designed to communicate universal knowledge without recourse to text, human linguistic systems or anthropomorphic content because it is assumed that recipients have no prior knowledge of humankind or the planet we inhabit. In addition to tracing and examining the history of interstellar communication during the period 1957-1977, I present an overview of scientific research on ‘interplanetary communication’ with the supposed inhabitants of Mars and other planets in the Solar System during the first half of the twentieth century. I show that it was not until the late 1950s that space exploration research provided the resources for humans to engage in systematic attempts to contact extraterrestrial civilizations in other star systems. My thesis focuses on two interstellar messages incorporated on specially designed material artifacts –NASA’s Pioneer plaque and Voyager Record—dispatched from Earth on board space probes during the 1970s. I critically examine how scientists designed and mobilized interstellar messages both to convey meaning and simultaneously support rhetorical claims about the universality of science and mathematics. I analyze how situated practices, craft skills and graphical technologies associated with scientific research on interstellar messages were deployed by scientists to produce and disseminate knowledge and support the claim that science and mathematics are universal. I examine the histories of technologies linked to space exploration including radio astronomy, television, communication satellites and space probes, tracing how knowledge practices and discourse associated with these technologies are enmeshed with the history of interstellar communication. In particular, I explain how and why television and other display technologies were appropriated by researchers working on interstellar communication to create visual representations of knowledge. I argue that televisual displays and radio telescopes constitute graphical technologies or ‘inscription devices’ deployed by scientists, media producers and others to translate natural objects, agency and culture into legible forms constituted in and through inscriptions, predominantly pictures and mathematical symbols, that convey knowledge within communication networks.
34

Space--Our Future: A Script for Group Interpretation

Bishop, Laura M. (Laura Maria) 08 1900 (has links)
The purpose of this thesis has been to prepare a group interpretation script based on the National Aeronautics and Space Administration and its major manned programs. The script is designed to inform high school students and the general public of the space program. Available literature on oral interpretation and readers theatre have been investigated with particular attention given to the value of readers theatre as a means of instruction. Questionnaires were circulated among aerospace professors throughout the country and companies involved in the space industry. In their responses, aerospace company officials indicate strong support of this thesis and indicate a pressing need for such an informative script.
35

Open Source IPSEC Software in Manned and Unmanned Space Missions

Edwards, Jacob 11 August 2012 (has links)
Network security is a major topic of research because cyber attackers pose a threat to national security. Securing ground-space communications for NASA missions is important because attackers could endanger mission success and human lives. This thesis describes how an open source IPsec software package was used to create a secure and reliable channel for ground-space communications. A cost efficient, reproducible hardware testbed was also created to simulate ground-space communications. The testbed enables simulation of low-bandwidth and high latency communications links to experiment how the open source IPsec software reacts to these network constraints. Test cases were built that allowed for validation of the testbed and the open source IPsec software. The test cases also simulate using an IPsec connection from mission control ground routers to points of interest in outer space. Tested open source IPsec software did not meet all the requirements. Software changes were suggested to meet requirements.
36

Navigation System Design with Application to the Ares I Crew Launch Vehicle and Space Launch Systems

Oliver, Ted Emerson 11 May 2013 (has links)
For a launch vehicle, the Navigation System is responsible for determining the vehicle state and providing state and state derived information for Guidance and Controls. The accuracy required of the Navigation System by the vehicle is dependent upon the vehicle, vehicle mission, and other consideration, such as impact foot print. NASAs Ares I launch vehicle and SLS are examples of launch vehicles with are/where to employ inertial navigation systems. For an inertial navigation system, the navigation system accuracy is defined by the inertial instrument errors to a degree determined by the method of estimating the initial navigation state. Utilization of GPS aiding greatly reduces the accuracy required in inertial hardware to meet the same accuracy at orbit insertion. For a launch vehicle with lunar bound payload, the navigation accuracy can have large implications on propellant required to correct for state errors during trans-lunar injection.
37

The Sputnik Crisis And America's Response

Kennedy, Ian 01 January 2005 (has links)
On 4 October 1957, the Soviet Union launched Sputnik, the world's first artificial satellite, and the Space Age had arrived. While not an American achievement, Sputnik stands as a significant juncture in United States history. This thesis explores the resulting American political crisis, its development in the final three months of 1957, and the impact Sputnik had on American life. The thesis also examines the social and political context of the Sputnik crisis and will challenge some long-standing analysis of how America's reaction to the Soviet satellite developed. To accomplish this task, it was necessary to consult both primary and secondary sources. Important primary sources include government documents from both the Legislative and Executive Branches of the United States Government, attained from both printed volumes and online archives. The memoirs of key individuals also shed light on the mindset of prominent politicians and policymakers of the period. Newspapers and magazines from the era were examined to explore the media and public reaction to the Sputnik Crisis and related events. Secondary sources are used as both avenues of information and theory regarding the events, and also for the purposes of examining the consensus of others who have explored this topic. The topics covered in the thesis include the flow of events before, during, and after the Sputnik Crisis of 1957; analysis of contextual issues such as missile and satellite development and American culture of the period; and analysis of how the Sputnik Crisis unfolded and how this impacted American culture and national policy.
38

Mental belastning inom bilkörning : En komparativ studie mellan olika körmiljöer

Karlsson, Kajsa January 2021 (has links)
The purpose of this study is to find out how the mental load varies among drivers in different driving environments, where the perceived stress will be compared with the biological stress while driving a car. Twenty-six experimental runs were performed where the driver drove a car in a real traffic environment. Test participants were both men and women between the ages of 20 and 48, where everyone who participated had a driving license. Galvanic Skin Response (GSR) was used to measuremental strain. After each run, the participants were asked to answer a questionnaire called NASA-TLX, a subjective multidimensional data load index. This is an evaluation tool used to measure the perceived workload. The participants’ self-assessment of the workload while driving was then compared with GSR data. The main result is that accessing the motorway and exiting the motorway means greater mental strain than the other driving environments. Data from GSR and NASA-TLX showed no difference, which means that the participants’ self-assessment is consistent with the physiological measure GSR.
39

Analysis of Low-Energy Lunar Transfers in a High-Fidelity Dynamics Model

Torchia, Patrick Jason 03 July 2023 (has links)
Renewed interest in returning to the Moon, emboldened by recent directives and missions by NASA, has necessitated the establishment of lunar infrastructure to support continuous human presence. With that, the objective of making this return more cost effective has gained significant importance. Low energy lunar transfers are more efficient ways to reach the Moon than the traditional Hohmann-type transfer. These trajectories leverage the multi-body gravitational effects to reduce overall delta-v requirements, in some cases removing the capture delta-v completely. While the time of flight for these transfers can be much longer than a Hohmann-type transfer, the chaotic design space of these transfers can enable large changes in arrival conditions at the Moon for small changes in initial conditions. Many investigations of these transfers take place in simplified dynamical models, such as the Planar Circular Restricted Three Body Problem, with very few higher-fidelity models being implemented. This approach is good to understand the dynamics of these trajectories as well as provide initial guesses for higher-fidelity models; but approximating the dynamics heavily make these models less applicable to mission design. This thesis aims to investigate the application of a higher-order model to simulate these trajectories. STK Astrogator was used to recreate the NASA GRAIL trajectory; and from the recreated trajectory, a nominal trajectory absent of mid-course corrections was established. This nominal trajectory was used to perform parametric and variational studies of departure and arrival conditions as well as compare to a nominal trajectory in a reduced-fidelity model. An investigation into the post launch correction burn requirements following launch vehicle under-performance was completed. Utilizing low energy transfers proved beneficial to adjusting arrival conditions for low delta-v requirements. All arrival inclinations are reasonably achievable for around 255 m/s. Using 255 m/s as a baseline, right ascension of the ascending node could be reached in a 40 degree range and argument of periapsis in a 50 degree range. Lunar insertion arrival can be varied by 7 hours on either side for less than 80 m/s. Trans-lunar injection epoch can be varied by 7 hours on either side of nominal departure for less than 4 m/s. Orbit radius and initial velocity are the most expensive errors to correct. These trajectories can be tuned to reduce the overall mid-course correction delta-v requirement for differing arrival inclinations if other orbital elements are relaxed. A relationship between placement of post-launch correction maneuver for velocity or radius errors was found. Comparing the trajectory in STK to the Inclined Bi-Elliptic Restricted Four Body problem, revealed that timing of the trajectory is variable while keeping the same arrival and departure conditions. However, solar radiation pressure cannot be ignored for more accurate simulation of these trajectories. This investigation has shown that low energy lunar transfers are a viable method to reach the Moon and their chaotic nature can be leveraged to relax restrictions in the design space. / Master of Science / Returning to the Moon has become a more important goal within the space industry. This has required more cost-efficient ways to reach the Moon; an important cost savings being fuel. Traditional ways to reach the Moon required large amounts of fuel to be expended to remain around the Moon after launch. Low energy lunar transfers aim to reduce fuel usage while still reaching the Moon, although they take much longer to reach their destination. Fuel and energy have direct comparisons and are used to evaluate these transfers. These transfers are highly susceptible to changes in their trajectory making them ideal for transferring to the Moon in different orientations. These changes can be made using very little fuel, allowing for more resources to be brought to the Moon. Navigating these transfers to the Moon require an accurate model of space for mission design.
40

PARAMETERS AFFECTING MENTAL WORKLOAD AND THE NUMBER OF SIMULATED UCAVS THAT CAN BE EFFECTIVELY SUPERVISED

Calkin, Bryan A. 18 April 2007 (has links)
No description available.

Page generated in 0.1206 seconds