Ballbot-Inspired orbital refueling depot and fluid-slosh effects on Spacecraft attitude dynamics

Orbital refueling has become a subject of increasing interest as longer, deep space missions and manned missions to the Moon and Mars are being contemplated once again. For fueling depots to become part of the infrastructure in space capable of enhancing deployment and service operations, there remains a slew of technical, operational, and engineering challenges which must be overcome. In this thesis, focus is placed mainly on the issue of fluid slosh and its effects on the spacecraft dynamics and the design of an attitude control system. In pursuit of overcoming the attitude tracking errors and instability from the fluid slosh, a novel satellite design is presented based on an omnidirectional ball-balanced robot (ball-bot) which aims at minimizing the control effort required to stabilize the satellite while also maximizing the amount of fuel it can carry. The satellite is comprised of two primary elements: a spherical tank, containing the fuel payload and a cuboid bus, containing the attitude control system (ACS) and other subsystems. The satellite bus is mobile and can displace itself over the surface of the sphere and has a sunshield which is deployed in orbit which shields the spherical tank from solar radiation. The cube is mobile and can displace itself on the surface of the sphere to point to the sun ensuring the protection of the fuel payload. A presentation of the state-of-the-art of orbital fuel depots is first presented, and subsequently, a contextualization of orbital dynamics, along with the mathematical modeling of the satellite, is carried out, complemented by a discussion about the limitations of the work and the assumptions of the model. A simulation of the satellite¿s dynamics with the fluid slosh is conducted using Simulink and the sun-tracking of the cuboid-bus with Mathematica. Finally, a set of conclusions are presented and recommendations for future research and improvements, based on the conclusions, are made.Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructur

Large space structures and systems in the space station era: A bibliography with indexes (supplement 05)

Bibliographies and abstracts are listed for 1363 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and July 31, 1992. Topics covered include technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion and solar power satellite systems

On-orbit serviceability of space system architectures

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2006.Includes bibliographical references (p. 171-182).On-orbit servicing is the process of improving a space-based capability through a combination of in-orbit activities which may include inspection; rendezvous and docking; and value-added modifications to a satellite's position, orientation, and operational status. As a means to extend the useful life or operational flexibility of spacecraft, on-orbit servicing constitutes one pathway to a responsive space enterprise. Following launch, traditional satellite operations are tightly constrained by an inability to access the orbiting vehicle. With the exception of software upgrades from ground controllers, operators are wedded to supporting payload technologies that become rapidly obsolete and to bus structures that deform during the stress of launch and degrade in the harsh environment of space. On-orbit servicing offers satellite operators an option for maintaining or improving space-based capabilities without launching a new spacecraft. Numerous studies have been performed on on-orbit servicing, particularly regarding the architecture of the servicing provider. Several customer valuation case studies have also been performed to identify the economic case (or lack thereof) for different categories of servicing missions.(cont.) Little work, however, has been done to analyze the tradespace of potential on-orbit servicing customers-a global analysis of operational satellites currently orbiting the Earth. The goal of this research is to develop and test a methodology to assess the physical amenability of satellites currently in operation to on-orbit servicing. As defined here, physical amenability of a target satellite, or "serviceability," refers to the relative complexity required of a teleoperated or autonomously controlled robotic vehicle to accomplish on-orbit servicing. A three-step process is followed to perform serviceability assessments. First, a taxonomy of space systems is constructed to add structure to the problem and to identify satellite attributes that drive servicing mission complexity. Second, a methodology is proposed to assess serviceability across the four servicing activities of rendezvous, acquire, access, and service.(cont.) This includes development of an agent-based model based on orbital transfers as well as a generalized framework in which serviceability is decomposed into four elements: (1) knowledge, (2) scale, (3) precision, and (4) timing. Third, the value of architecture frameworks and systems engineering modeling languages for conducting serviceability assessments is explored through the development of a discrete event simulation of the Hubble Space Telescope. The thesis concludes with prescriptive technical considerations for designing serviceable satellites and a discussion of the political, legal, and financial challenges facing servicing providers.by Matthew G. Richards.S.M