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  • 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.
11

Developing Communication and Data Systems for Space Station Facility Class Payloads

Hazra, Tushar K., Sun, Charles, Mian, Arshad M., Picinich, Louis M. 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / The driving force in modern space mission control has been directed towards developing cost effective and reliable communication and data systems. The objective is to maintain and ensure error-free payload commanding and data acquisition as well as efficient processing of the payload data for concurrent, real time and future use. While Mainframe computing still comprises a majority of commercially available communication and data systems, a significant diversion can be noticed towards utilizing a distributed network of workstations and commercially available software and hardware. This motivation reflects advances in modem computer technology and the trend in space mission control today and in the future. The development of communication and data involves the implementation of distributed and parallel processing concepts in a network of highly powerful client server environments. This paper addresses major issues related to developing and integrating communication and data system and the significance for future developments.
12

PREPARING A COTS GROUND TELEMETRY RECEIVER FOR USE IN THE INTERNATIONAL SPACE STATION

Champion, James 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Within the industry, telemetry receivers are used in ground-based telemetry receiving stations to receive telemetry data from air or space-based sources. Equipment for the typical telemetry application is widely available. But when requirements create the need for a space-based telemetry receiver to uplink data from the ground, what are the choices for equipment? In such situations, adapting COTS equipment may present the only solution to meet delivery and budgetary constraints. The first part of this paper provides technical and contractual points a COTS supplier needs to consider when bidding on a COTS contract. The second part of this paper covers a project concerned with modification of a general-purpose ground telemetry receiver for use on the International Space Station. The information within the paper is useful to other engineers and companies considering contracts to modify COTS equipment for use on Shuttle or other space-based projects.
13

Microbial responses to extreme radiation environments

Wadsworth, Jennifer Louise January 2018 (has links)
Microorganisms are known to tolerate a variety of extreme environments, such as high and low pH, desiccation and a wide range of temperatures that would prove uninhabitable for most eukaryotic cells. However, extreme radiation exposure is a ubiquitous hazard to pro- and eukaryotic viability. Ionising and non-ionising radiation, and their associated high energies, cause damage to a cell in the form of DNA double-strand breaks, membrane deterioration, and lethal mutations. Radiation also induces secondary effects such as the production of reactive oxygen species, which attack and degrade organic compounds. It is therefore not surprising that radiation is considered by the scientific community to be one of the main influencing factors when regarding habitability on the early Earth, as well as other planets, such as present-day Mars. This thesis explores the response of select microbes that have been exposed to extreme radiation environments, i.e. both high and ultra-low radiation. Understanding how radiation affects the geochemical environment is key to the assessment of its potential to support life and to harbour molecules associated with life. The effect of radiation-induced photochemistry on the early terrestrial and present-day Martian surface is explored in conjunction with Fenton chemistry. Iron oxides are abundant on both Earth and Mars and act as catalysts in Photo-Fenton reactions, enabling the production of free radicals. The resulting consequences for habitability are shown to be antagonistic, with iron oxide enabling both the protection or destruction of cells, depending on the local geochemistry. In addition, the photo-reactivity of perchlorate is investigated. The UV-induced activation of the strong oxidant, and recently confirmed Martian surface constituent, is demonstrated, revealing its severe bacteriocidal effect on microbes. It is also shown to significantly reduce microbial viability when combined with further Martian soil constituents and components required for Photo-Fenton chemistry. In order to accurately analyse the effects of low earth orbit radiation on prokaryotic life, cyanobacterial samples were attached to the outside of the International Space Station as part of the EXPOSE-R2 mission for 1.5 years. The samples were subjected to various conditions, including exposure to a minimally filtered space radiation environment and simulated Mars conditions. The experiment is designed to test the protection that biogenic and non-biogenic substances may provide to cells. The results in this work present the post-flight analysis of the samples and demonstrate the ability of these substances to maintain cyanobacteria viability. They also show that the cyanobacterial cells themselves can effectively act as a shield for a secondary, co-cultured bacteria species. On the other end of the radiation dose scale, this work addresses the gaps in knowledge with regard to the little-understood effects of low, sub-background radiation on prokaryotes. Using the Boulby Underground Lab in the functioning Boulby Mine, Cleveland UK, microbes are cultivated under regulated, extremely low radiation environments to test multiple dose-response models. The results show no change in cell's growth rates or gradients in low radiation exposure when compared to surface-dose controls. They also fail to exhibit any enhanced susceptibility to stress factors, such as UV irradiation, as suggested by previous work in the field. These experiments mark the first extensive and tightly controlled research into microbial responses in the near-absence of radiation. This work illustrates the importance of understanding both primary and secondary effects of radiation on microbes and begins to bridge the knowledge gap from both ends of the dose axis. These approaches show the far-reaching influence radiation has on astrobiologically relevant topics, such as habitat geochemistry and life detection, and demonstrate the capacity of life to survive in extreme radiation environments.
14

Gravitational geomicrobiology : biofilms and their mineral interactions under terrestrial and altered gravity

Nicholson, Natasha Elizabeth January 2018 (has links)
Experiments with microbial biofilms in microgravity and simulated microgravity have revealed altered growth kinetics, but geomicrobial biofilms have not yet been studied in low gravity environments. No characterisation of biofilms, geomicrobial or otherwise, have been conducted at hypergravity. This thesis explores factors affecting microbe-mineral interactions under terrestrial conditions, lays the groundwork for a scheduled microgravity experiment, and provides the first data on biofilms grown at hypergravity. As a first step in understanding microbe-mineral interactions in altered gravity environments, experiments were undertaken to identify factors that constrain attachment in a terrestrial environment. The model organism Sphingomonas desiccabilis and basaltic rock from Iceland were selected, and the minerals that make up the basalt were identified and procured in their pure form. The relative significance of physical factors such as hydrophobicity, surface charge, porosity and nutritional value were examined in relationship to the success with which biofilms colonised the mineral surfaces. Growth was measured by the quantity of biofilm biomass after a ifxed time period, using Crystal Violet stain, in order to draw conclusions about the most influential physical conditions on biofilm attachment to a substrate. It was found that mineral attachment is influenced more by porosity and nutritional value than by hydrophobicity or surface charge. To explore how reduced gravity affects biofilm formation and weathering rates, a European Space Agency experiment, BioRock, is underway. Samples of basalt, with monocultures of three different organisms, will be sent to the International Space Station in 2019 for long-term exposure to Martian and micro-gravity. Research testing proof of concepts, material compatibility, and experimental procedure and equipment is described. Confocal laser scanning microscopy (CLSM) was used to image the biofilms, and inductively coupled plasma mass spectroscopy (ICP-MS) experiments were conducted to compare biotic and abiotic elemental release rates from basalt. Both of these methods will be employed for post-flight analysis of BioRock. Preliminary terrestrial ICP-MS experiments indicated that rare Earth elements (REEs) showed the most reliable reflection of leaching patterns overall, as a consequence of their high molecular weight and low volatility during the ashing procedure. To fully understand gravity's effect on microbiological processes it is important to investigate what occurs when its influences are removed, but also to establish what occurs when extra gravitational force is applied. Using simulated hypergravity, achieved through hyper-acceleration on a geotechnical centrifuge, the effects of 10 x g on biofilm development and the leaching of basalt were investigated. As this was the first time that biofilms had been studied under hypergravity, additional substrates were included with the basalt, to enable characterisation of the more general response of biofilms to hypergravity. In contrast to previous experiments conducted on planktonic bacteria, which found decreased population sizes, the biofilms grown at 10 x g showed greater biomass than the 1 x g samples. ICP-MS showed no difference in the average weathering rates, but greater variability in the higher gravity samples. The data collected here advances our understanding of microbial interactions with geologically important substrates, with implications for an ISS microgravity experiment and future human space exploration. It also presents new intelligence on the previously unstudied effects of hypergravity on biofilms and rock weathering.
15

Interim Access to the International Space Station

Smith, Tyson Karl 01 December 2009 (has links)
This thesis evaluates mission scenarios using the existing Evolved Expendable Launch Vehicles for delivering the Crew Exploration Vehicle to the International Space Station. The Space Shuttle is scheduled to retire in the year 2011 and the Ares I is being developed to replace it. With its current schedule, the earliest that the Ares I will become fully operational is 2016. The configurations in this thesis are presented to narrow the gap in which the USA does not have direct access to the International Space Station. They also present "buy down" options for the USA human space operations, if the current development issues of the Ares I cause it to not become operational at all. The three Launch options presented are the Atlas V HLV, the Delta IV Heavy, and the Delta IV with three common core boosters as the first stage and the Orion service module to be used as the second stage. The first configuration, the Atlas V HLV requires significant impulse from the Orion service module in order to reach the final International Space Station orbit. The second option, the Delta IV Heavy, launches the Orion as a passive payload and requires no impulsive maneuvering from the service module in order to reach the International Space Station orbit. The third configuration, the Delta IV Heavy with three common core boosters as the first stage, and the Orion spacecraft acting as the second stage, requires significant impulse from Orion's service module engine to achieve the International Space Station orbit. After final orbit insertion all three configurations still have sufficient propellent for de-orbit and re-entry.The third configuration has a certain appeal, by eliminating the second stage only the common core booster on the Delta IV Heavy system need be human-rated. Finally, reliability and development cost assessments are presented and compared to the Ares I.
16

Trade Study of Decomissioning Strategies for the International Space Station

Herbort, Eric 06 September 2012 (has links)
This thesis evaluates decommissioning strategies for the International Space Station ISS. A permanent solution is attempted by employing energy efficient invariant manifolds that arise in the circular restricted three body problem CRTBP to transport the ISS from its low Earth orbit LEO to a lunar orbit. Although the invariant manifolds provide efficient transport, getting the the ISS onto the manifolds proves quite expensive, and the trajectories take too long to complete. Therefore a more practical, although temporary, solution consisting of an optimal re-boost maneuver with the European Space Agency's automated transfer vehicle ATV is proposed. The optimal re-boost trajectory is found using control parameterization and the sequential quadratic programming SQP algorithm. The model used for optimization takes into account the affects of atmospheric drag and gravity perturbations. The optimal re-boost maneuver produces a satellite lifetime of approximately ninety-five years using a two ATV strategy.
17

INITIAL DESIGN, MANUFACTURE, AND TESTING OF A CUBELAB MODULE FRAME FOR BIOLOGICAL PAYLOADS ABOARD THE INTERNATIONAL SPACE STATION

Clements, Twyman Samuel 01 January 2011 (has links)
This thesis investigates the design of a CubeLab Module frame to facilitate biological research aboard the International Space Station (ISS). With the National Laboratory designation of the ISS by the United States Congress the barriers for use of the facility have been lowered for commercial and academic entities, allowing greater volume and diversity in the research that can be done. Researchers in biology and other areas could benefit from development and adoption of a plug-and-play payload containment system for use in the microgravity/space environment of the ISS. This research includes design and analysis of such a system. It also includes production and testing of a prototype. The relevant NASA requirements are documented, and they were considered during the design phase. Results from finite element analyses to predict performance of a proposed design under expected service conditions are reported. Results from functional testing of the prototype are also provided. A discussion of future work needed before the structure outlined in this thesis can become commercially viable is also presented.
18

Transatlantic relations the role of nationalism in multinational space cooperation /

Crooks, Heather R. January 2009 (has links) (PDF)
Thesis (M.A. in Security Studies (Europe and Eurasia))--Naval Postgraduate School, June 2009. / Thesis Advisor(s): Abenheim, Donald. "June 2009." Description based on title screen as viewed on July 13, 2009. Author(s) subject terms: NASA, European Space Agency, ESA, International Cooperation, Transatlantic Relations, Nationalism, INTELSAT, Ulysses, Galileo, SOFIA, ISS, International Space Station, Constellation, Aurora, Vision for Space Exploration, Moon, Mars. Includes bibliographical references (p. 85-95). Also available in print.
19

ICE Cubes Mission: Design, Development and Documentation of the Cube-Zero System

Mannes, Quentin January 2017 (has links)
The International Space Station provides a high-quality of microgravity and extended exposure time which makes it a platform of choice for microgravity research. In order to increase accessibility of onboard experimentation, Space Applications Services will soon launch the ICE Cubes facility as part of its ICE Cubes Service. The facility is foreseen to host standardized plug-and-play payload cubes to reduce overall cost and procedure time required to install payloads on the station. To remotely support the facility it is decided to develop a utility cube named Cube-Zero that will be launched and installed with the facility on the station. This thesis work included the complete design, development and documentation of the cube. The thesis started by conducting a preliminary needs and market study from which two specific purposes were defined for the cube. In addition to its original function of support-utility, the cube is tasked to be a technical commercial demonstrator for the service. This led to the conceptual design of the cube as a multidisciplinary framework able to host two user-defined experiment modules. The preliminary concept was further refined in this paper and with support of prototypes, simulations and analyses led to a final functional design for the Cube-Zero. The work is concluded with the manufacturing of an engineering model of the cube. The model is fully operational, can support the test of the facility before launch and can demonstrate to users its versatility and ease of use in operating any kind of experiment module. Eventually, the information gathered in this thesis report will support future users into developing their own Cube-Zero payload module and guide Space Applications Services into manufacturing, testing and operating the Cube-Zero protoflight model. / ICE Cubes
20

Capillary Phenomena: Investigations in Compressed Bubble Migration, Geometric Wetting, and Blade-Bound Droplet Stability

Blackmore, William Henry 04 January 2013 (has links)
Capillary flows continue to be important in numerous spacecraft systems where the effective magnitude of the gravity vector is approximately one millionth that of normal Earth gravity. Due to the free fall state of orbiting spacecraft, the effects of capillarity on the fluid systems onboard can dominate the fluid behavior over large length scales. In this research three investigations are pursued where the unique interplay between surface tension forces, wetting characteristics, and system geometry control the fluid behavior, whether in large systems aboard spacecraft, or micro-scale systems on Earth. First, efforts in support of two International Space Station (ISS) experiments are reported. A description of the development of a new NASA ground station at Portland State University is provided along with descriptions of astronaut training activities for the proper operation of four handheld experiments currently in orbit as part of the second iteration of the Capillary Flow Experiments (CFE-2). Concerning the latter, seven more vessels are expected to be launched to the ISS shortly. Analysis of the data alongside numerical simulations shows excellent agreement with theory, and a new intuitive method of viewing critical wetting angles and fluid bulk shift phenomena is offered. Secondly, during the CFE-2 space experiments, unplanned peripheral observations revealed that, on occasion, rapidly compressed air bubbles migrate along paths with vector components common to the residual acceleration onboard the ISS. Unexpectedly however, the migration velocities could be shown to be up to three orders of magnitude greater than the appropriate Stokes flow limit! Likely mechanisms are explored analytically and experimentally while citing prior theoretical works that may have anticipated such phenomena. Once properly understood, compressed bubble migration may be used as an elegant method for phase separation in spacecraft systems or microgravity-based materials manufacturing. Lastly, the stability of drops on surfaces is important in a variety of natural and industrial processes. So called 'wall-edge-vertex bound drops' (a.k.a. drops on blade tips or drops on leaf tips which they resemble) are explored using a numerical approach which applies the Surface Evolver algorithm through implementation of a new file layer and a multi-parameter sweep function. As part of a recently open sourced SE-FIT software, thousands of critical drop configurations are efficiently computed as functions of contact angle, blade edge vertex half-angle, and g-orientation. With the support of other graduate students, simple experiments are performed to benchmark the computations which are then correlated for ease of application. It is shown that sessile, pendant, and wall-edge bound drops are only limiting cases of the more generalized blade-bound drops, and that a ubiquitous 'dry leaf tip' is observed for a range of the critical geometric and wetting parameters.

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