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  • 1
    Language: English
    In: Acta Astronautica, May 2018, Vol.146, pp.378-386
    Description: “Space Settlements” – i.e., permanent human communities beyond Earth's biosphere – have been discussed within the space advocacy community since the 1970s. Now, with the end of the International Space Station (ISS) program fast approaching (planned for 2024–2025) and the advent of low cost Earth-to-orbit (ETO) transportation in the near future, the concept is coming once more into mainstream. Considerable attention has been focused on various issues associated with the engineering and human health considerations of space settlement such as artificial gravity and radiation shielding. However, relatively little attention has been given to the biological implications of a self-sufficient space settlement. Three fundamental questions are explored in this paper: (1) what are the biological “foundations” of truly self-sufficient space settlements in the foreseeable future, (2) what is the minimum scale for such self-sustaining human settlements, and (3) what are the integrated biologically-driven system requirements for such settlements? The paper examines briefly the implications of the answers to these questions in relevant potential settings (including free space, the Moon and Mars). Finally, this paper suggests relevant directions for future research and development in order for such space settlements to become viable in the future.
    Keywords: Engineering
    ISSN: 0094-5765
    E-ISSN: 1879-2030
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  • 2
    Language: English
    In: Science (New York, N.Y.), 01 November 2002, Vol.298(5595), pp.981-7
    Description: Stabilizing the carbon dioxide-induced component of climate change is an energy problem. Establishment of a course toward such stabilization will require the development within the coming decades of primary energy sources that do not emit carbon dioxide to the atmosphere, in addition to efforts to reduce end-use energy demand. Mid-century primary power requirements that are free of carbon dioxide emissions could be several times what we now derive from fossil fuels (approximately 10(13) watts), even with improvements in energy efficiency. Here we survey possible future energy sources, evaluated for their capability to supply massive amounts of carbon emission-free energy and for their potential for large-scale commercialization. Possible candidates for primary energy sources include terrestrial solar and wind energy, solar power satellites, biomass, nuclear fission, nuclear fusion, fission-fusion hybrids, and fossil fuels from which carbon has been sequestered. Non-primary power technologies that could contribute to climate stabilization include efficiency improvements, hydrogen production, storage and transport, superconducting global electric grids, and geoengineering. All of these approaches currently have severe deficiencies that limit their ability to stabilize global climate. We conclude that a broad range of intensive research and development is urgently needed to produce technological options that can allow both climate stabilization and economic development.
    Keywords: Sciences (General) ; Biology;
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 3
    In: Journal of Aerospace Engineering, April, 2001, Vol.14(2), p.38
    Description: Large space solar-power systems have intermittently been a topic for consideration during the past 30 years. However, the last major studies in the United States on these concepts were conducted in the late 1970s. After two decades of relative inactivity, large-scale space solar power (SSP), including the generation of solar power in space for transmission to terrestrial markets, has recently reemerged as a potential energy option. This occurrence is timely because global energy demand continues to grow dramatically while environmental concerns increase. Demand for power in space is also likely to increase during the same time frame. A wide range of technology advances would be needed to enable such systems. In addition to very low cost space transportation and highly efficient and high voltage solar arrays, significant developments must also take place in technologies such as wireless power transmission, large space structures, robotic assembly and maintenance, and others. However, recent NASA studies and focused research and development progress in a number of key areas suggest that such systems are technically feasible. This paper presents an overview of the subject of space solar power, including results of recent NASA activities.
    Keywords: Solar Energy -- Usage ; Power Resources -- Innovations
    ISSN: 0893-1321
    E-ISSN: 19435525
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  • 4
    In: Journal of Aerospace Engineering, April, 2001, Vol.14(2), p.46
    Description: The capability to generate power in space for transmission to terrestrial markets is a long-term visionary goal that embodies a wide range of technical challenges. Space solar-power (SSP) systems will be very large, but they must be affordable if they are to be developed some day. Addressing the technologies required to construct gigawatt-class, commercial "solar-power satellites" in the distant future can open many other applications opportunities in space and on Earth in the near future. Technical hurdles have been explored and characterized by NASA's recent SSP Exploratory Research and Technology Program. The strategic technology areas examined include solar power generation; wireless power transmission; onboard power management and distribution; structural concepts, materials, and controls; and others. Important progress has been achieved since major space power system studies were conducted in the 1970s. However, significant and highly challenging research and technology development must be conducted successfully across a wide range of areas so that affordable and abundant SSP can be realized.
    Keywords: Solar Energy -- Usage ; Power Transmission (Mechanical) -- Innovations ; Power Resources -- Innovations
    ISSN: 0893-1321
    E-ISSN: 19435525
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Acta Astronautica, 2009, Vol.65(1), pp.146-156
    Description: Several of the central issues associated with the eventual realization of the vision of solar power from space for terrestrial markets resolve around the expect costs associated with the assembly, inspection, maintenance and repair of future solar power satellite (SPS) stations. In past studies (for example, NASA's “Fresh Look Study”, c. 1995–1997) efforts were made to reduce both the scale and mass of large, systems-level interfaces (e.g., the power management and distribution (PMAD) system) and on-orbit fixed infrastructures through the use of modular systems strategies. These efforts have had mixed success (as reflected in the projected on-orbit mass of various systems concepts. However, the author remains convinced of the importance of modular strategies for exceptionally large space systems in eventually realizing the vision of power from space. This paper will introduce some of the key issues associated with cost-competitive space solar power in terrestrial markets. It will examine some of the relevant SPS concepts and will assess the ‘pros and cons’ of each in terms of space assembly, maintenance and servicing (SAMS) requirements. The paper discusses at a high level some relevant concepts and technologies that may play r role in the eventual, successful resolution of these challenges. The paper concludes with an example of the kind of novel architectural approach for space solar power that is needed.
    Keywords: Engineering
    ISSN: 0094-5765
    E-ISSN: 1879-2030
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  • 6
    Language: English
    In: Acta Astronautica, 2009, Vol.65(9), pp.1190-1195
    Description: The current emphasis in the US and internationally on lunar robotic missions is generally viewed as a precursor to possible future human missions to the Moon. As initially framed, the implementation of high level policies such as the US Vision for Space Exploration (VSE) might have been limited to either human lunar sortie missions, or to the testing at the Moon of concepts-of-operations and systems for eventual human missions to Mars [White House, Vision for Space Exploration, Washington, DC, 14 January, 2004. ]. However, recently announced (December 2006) US goals go much further: these plans now place at the center of future US—and perhaps international—human spaceflight activities a long-term commitment to an outpost on the Moon. Based on available documents, a human lunar outpost could be emplaced as early as the 2020–2025 timeframe, and would involve numerous novel systems, new technologies and unique operations requirements. As such, substantial investments in research and development (R&D) will be necessary prior to, during, and following the deployment of such an outpost. It seems possible that such an outpost will be an international endeavor, not just the undertaking of a single country—and the US has actively courted partners in the VSE. However, critical questions remain concerning an international lunar outpost. What might such an outpost accomplish? To what extent will “sustainability” be built into the outpost? And, most importantly, what will be the outpost's life cycle cost (LCC)? This paper will explore these issues with a view toward informing key policy and program decisions that must be made during the next several years. The paper will (1) describe a high-level analytical model of a modest lunar outpost, (2) examine (using this model) the parametric characteristics of the outpost in terms of the three critical questions indicated above, and (3) present rough estimates of the relationships of outpost goals and “sustainability” to LCC. The paper will also consider possible outpost requirements for near-term investments in enabling research in light of experiences in past advanced technology programs.
    Keywords: Engineering
    ISSN: 0094-5765
    E-ISSN: 1879-2030
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  • 7
    Language: English
    In: Acta Astronautica, 2009, Vol.65(9), pp.1216-1223
    Description: The development of new system capabilities typically depends upon the prior success of advanced technology research and development efforts. These systems developments inevitably face the three major challenges of any project: performance, schedule and budget. Done well, advanced technology programs can substantially reduce the uncertainty in all three of these dimensions of project management. Done poorly, or not at all, and new system developments suffer from cost overruns, schedule delays and the steady erosion of initial performance objectives. It is often critical for senior management to be able to determine which of these two paths is more likely—and to respond accordingly. The challenge for system and technology managers is to be able to make clear, well-documented assessments of technology readiness and risks, and to do so at key points in the life cycle of the program. In the mid 1970s, the National Aeronautics and Space Administration (NASA) introduced the concept of “technology readiness levels” (TRLs) as a discipline-independent, programmatic figure of merit (FOM) to allow more effective assessment of, and communication regarding the maturity of new technologies. In 1995, the TRL scale was further strengthened by the articulation of the first definitions of each level, along with examples (J. Mankins, Technology readiness levels, A White Paper, NASA, Washington, DC, 1995. ). Since then, TRLs have been embraced by the U.S. Congress’ General Accountability Office (GAO), adopted by the U.S. Department of Defense (DOD), and are being considered for use by numerous other organizations. Overall, the TRLs have proved to be highly effective in communicating the status of new technologies among sometimes diverse organizations. This paper will review the concept of “technology readiness assessments”, and provide a retrospective on the history of “TRLs” during the past 30 years. The paper will conclude with observations concerning prospective future directions for the important discipline of technology readiness assessments.
    Keywords: Engineering
    ISSN: 0094-5765
    E-ISSN: 1879-2030
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  • 8
    Language: English
    In: Acta Astronautica, 2009, Vol.65(9), pp.1208-1215
    Description: Systems that depend upon the application of new technologies inevitably face three major challenges during development: performance, schedule and budget. Technology research and development (R&D) programs are typically advocated based on argument that these investments will substantially reduce the uncertainty in all three of these dimensions of project management. However, if early R&D is implemented poorly, then the new system developments that plan to employ the resulting advanced technologies will suffer from cost overruns, schedule delays and the steady erosion of initial performance objectives. It is often critical for senior management to be able to determine which of these two paths is more likely—and to respond accordingly. The challenge for system and technology managers is to be able to make clear, well-documented assessments of technology readiness and risks, and to do so at key points in the life cycle of the program. Several approaches have been used to evaluate technology maturity and risk in order to better anticipate later system development risks. The “technology readiness levels” (TRLs), developed by NASA, are one discipline-independent, programmatic figure of merit (FOM) that allows more effective assessment of, and communication regarding the maturity of new technologies. Another broadly used management tool is of the “risk matrix”, which depends upon a graphical representation of uncertainty and consequences. However, for the most part these various methodologies have had no explicit interrelationship. This paper will examine past uses of current methods to improve R&D outcomes and will highlight some of the limitations that can arise. In this context, a new concept for the integration of the TRL methodology, and the concept of the “risk matrix” will be described. The paper will conclude with observations concerning prospective future directions for the important new concept of integrated “technology readiness and risk assessments”.
    Keywords: Engineering
    ISSN: 0094-5765
    E-ISSN: 1879-2030
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  • 9
    Language: English
    In: Energy Procedia, 2014, Vol.49, pp.1916-1921
    Description: With funding from the U.S. Department of Energy (DOE) and SolarThermoChemical LLC, PNNL is developing a solar-powered steam-methane reformer (SMR). The reformer sits at the focal point of a parabolic dish concentrator, with the concentrated solar energy providing the endothermic heat of reaction. The result is a syngas comprising mostly H2 and CO with a heating value approximately 27% higher than the entering natural gas. On-sun testing completed in 2013 achieved a solar-to-chemical energy conversion efficiency as high as 69%, based on the ratio of incremental chemical energy created to direct normal insolation striking the parabolic dish concentrator. Advanced designs are expected to improve upon this performance. Details regarding the design and performance of the solar reformer are presented elsewhere. This paper describes the projected economics of the parabolic dish SMR system. The key metrics are the levelized cost of electricity for a modified, combined-cycle power plant that operates with natural gas or syngas from the dish SMR, and the levelized cost of chemical energy based on the incremental chemical energy produced in the SMR. The latter can be compared to the levelized cost of natural gas over the life of the solar-powered system. Initial capital and annual maintenance cost estimates for each system component are also presented.
    Keywords: Solar ; Steam-Methane Reforming ; Cost ; Economic ; Engineering ; Economics
    ISSN: 1876-6102
    E-ISSN: 1876-6102
    Source: ScienceDirect Journals (Elsevier)
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  • 10
    Language: English
    In: Science, 01 November 2002, Vol.298(5595), pp.981-987
    Description: Stabilizing the carbon dioxide-induced component of climate change is an energy problem. Establishment of a course toward such stabilization will require the development within the coming decades of primary energy sources that do not emit carbon dioxide to the atmosphere, in addition to efforts to reduce end-use energy demand. Mid-century primary power requirements that are free of carbon dioxide emissions could be several times what we now derive from fossil fuels ( $\sim10^{13}$ watts), even with improvements in energy efficiency. Here we survey possible future energy sources, evaluated for their capability to supply massive amounts of carbon emission-free energy and for their potential for large-scale commercialization. Possible candidates for primary energy sources include terrestrial solar and wind energy, solar power satellites, biomass, nuclear fission, nuclear fusion, fission-fusion hybrids, and fossil fuels from which carbon has been sequestered. Non-primary power technologies that could contribute to climate stabilization include efficiency improvements, hydrogen production, storage and transport, superconducting global electric grids, and geoengineering. All of these approaches currently have severe deficiencies that limit their ability to stabilize global climate. We conclude that a broad range of intensive research and development is urgently needed to produce technological options that can allow both climate stabilization and economic development.
    Keywords: Fossil Fuels ; Climatic Changes ; Man-Induced Effects ; Greenhouse Effect ; Hydrogen ; Nuclear Power Plants ; Economic Feasibility ; Wind Power ; Energy Resources ; Solar Power ; Carbon Dioxide ; Biogas ; Fuel Economy ; Pollution Control ; Technology ; Atmospheric Pollution Control ; Climatic Change Causes ; Atmospheric Pollution Emission ; Carbon Dioxide in the Atmosphere ; Anthropogenic Climate Changes ; Climatic Changes ; Greenhouse Effect ; Air Pollution Control ; Nuclear Energy ; Human Factors ; Carbon Dioxide ; Energy Sources ; Solar Energy ; Biogas ; Freshwater ; Brackish ; Marine ; Prevention and Control ; Environmental Influences (551.588) ; Air Pollution;
    ISSN: 00368075
    E-ISSN: 10959203
    Source: Archival Journals (JSTOR)
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