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  • Spacecraft Propulsion and Power  (1,025)
  • Fisheries
  • LUNAR AND PLANETARY EXPLORATION
  • Life and Medical Sciences
  • 2000-2004  (1,052)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Agriculture and human values 17 (2000), S. 125-139 
    ISSN: 1572-8366
    Keywords: Environment ; Fisheries ; Fordism ; Nation-State ; Regulation ; Supranational State ; Transnational corporations ; Transnational State
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This analysis uses an analytical frameworkgrounded in political economy perspectives of theglobalization of the agro-food sector combined with acase study approach focusing on the Marine StewardshipCouncil (MSC) to inform discussions regarding thecharacteristics of societal regulation in thepost-Fordist era. More specifically, this analysisuses the case of the emergence of the MSC toinvestigate propositions regarding the existence of,and location of, nascent forms of a transnationalState. The MSC proposes to regulate the certificationof sustainable fisheries at the global level throughan eco-labeling program. The MSC was created in 1996by the transnational environmental organization theWorld Wildlife Fund and the transnational corporationUnilever. The emergence of the MSC has generatedheated discussion in fisheries management circles thatis in general divided along North/South lines. Thisanalysis indicates that the case of the MSC providesvaluable insights into the possible characteristics ofsupranational regulatory mechanisms that might emulatethe role of the nation-State in the post-Fordist era.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Environment, development and sustainability 2 (2000), S. 277-304 
    ISSN: 1573-2975
    Keywords: Systems of Knowledge ; Local Knowledge ; Fisheries ; Resource Management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Sociology
    Notes: Abstract During the last 20 years, the existence of rich systems of local knowledge, and their vital support to resource use and management regimes, has been demonstrated in a wide range of biological, physical and geographical domains, such as agriculture, animal husbandry, forestry and agroforestry, medicine, and marine science and fisheries. Local knowledge includes empirical and practical components that are fundamental to sustainable resource management. Among coastal-marine fishers, for example, regular catches and, often, long-term resource sustainment are ensured through the application of knowledge that encompasses empirical information on fish behaviour, marine physical environments, fish habitats and the interactions among ecosystem components, as well as complex fish taxonomies. Local knowledge is therefore an important cultural resource that guides and sustains the operation of customary management systems. The sets of rules that compose a fisheries management system derive directly from local concepts and knowledge of the resources on which the fishery is based. Beyond the practical and the empirical, it is essential to recognise the fundamental socio-cultural importance of local knowledge to any society. It is through knowledge transmission and socialisation that worldviews are constructed, social institutions perpetuated, customary practices established, and social roles defined. In this manner, local knowledge and its transmission, shape society and culture, and culture and society shape knowledge. Local knowledge is of great potential practical value. It can provide an important information base for local resources management, especially in the tropics, where conventionally-used data are usually scarce to non-existent, as well as providing a shortcut to pinpoint essential scientific research needs. To be useful for resources management, however, it must be systematically collected and scientifically verified, before being blended with complementary information derived from Western-based sciences. But local knowledge should not be looked on with only a short-term utilitarian eye. Arguments widely accepted for conserving biodiversity, for example, are also applicable to the intellectual cultural diversity encompassed in local knowledge systems: they should be conserved because their utility may only be revealed at some later date or owing to their intrinsic value as part of the world's global heritage. At least in cultures with a Western liberal tradition, more than lip-service is now being paid to alternative systems of knowledge. The denigration of alternative knowledge systems as backward, inefficient, inferior, and founded on myth and ignorance has recently begun to change. Many such practices are a logical, sophisticated and often still-evolving adaptation to risk, based on generations of empirical experience and arranged according to principles, philosophies and institutions that are radically different from those prevailing in Western scientific circles, and hence all-but incomprehensible to them. But steadfastly held prejudices remain powerful. In this presentation I describe the 'design principles' of local knowledge systems, with particular reference to coastal-marine fishing communities, and their social and practical usefulness. I then examine the economic, ideological and institutional factors that combine to perpetuate the marginalisation and neglect of local knowledge, and discuss some of the requirements for applying local knowledge in modern management.
    Type of Medium: Electronic Resource
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  • 3
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-10-11
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stone, Richard -- New York, N.Y. -- Science. 2003 Oct 10;302(5643):221-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14551417" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Ecosystem ; *Eels/growth & development/physiology ; Fisheries ; Fresh Water ; Oceans and Seas ; Population Density ; Reproduction ; Seawater
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-08-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- New York, N.Y. -- Science. 2003 Aug 22;301(5636):1034-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12933987" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Anthozoa ; Atlantic Ocean ; Conservation of Natural Resources ; *Ecosystem ; Environment ; Fisheries ; *Fishes ; Geologic Sediments ; *Marine Biology ; Pacific Ocean ; *Seawater
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2000-08-19
    Description: At a press conference on 27 July, the National Marine Fisheries Service (NMFS) released a long-awaited plan to save the Columbia River's endangered salmon by restoring fish habitat, overhauling hatcheries, limiting harvest, and improving river flow. What the plan did not do, however, was call for immediate breaching of four dams on the Snake River, the Columbia's major tributary--an option that has been the subject of a nationwide environmental crusade. The NMFS will hold that option in abeyance while it sees whether the less drastic measures will do the trick. Responses from both sides were immediate and outraged.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mann, C C -- Plummer, M L -- New York, N.Y. -- Science. 2000 Aug 4;289(5480):716-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10950712" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Conservation of Natural Resources ; *Ecosystem ; Fisheries ; Fresh Water ; Government Agencies ; Northwestern United States ; *Salmon
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2001-08-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Magnuson, J J -- Safina, C -- Sissenwine, M P -- New York, N.Y. -- Science. 2001 Aug 17;293(5533):1267-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Limnology, University of Wisconsin, Madison, WI 53706, USA. jmagnuson@mhub.limnology.wisc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11509715" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Identification Systems ; Animals ; Atlantic Ocean ; *Behavior, Animal ; Body Temperature ; *Conservation of Natural Resources ; Diving ; *Ecosystem ; Fisheries ; Population Dynamics ; Reproduction ; Swimming ; Tuna/genetics/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-03-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, D -- New York, N.Y. -- Science. 2001 Jan 12;291(5502):227-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11253825" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Fisheries ; *Homing Behavior ; Isotopes ; Otolithic Membrane/*chemistry ; Perciformes/*physiology ; Population Dynamics ; Reproduction ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-02-24
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Collie, J -- Saila, S -- Walters, C -- Carpenter, S -- New York, N.Y. -- Science. 2000 Nov 3;290(5493):933-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11184733" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Conservation of Natural Resources ; *Ecosystem ; Fisheries ; Fresh Water ; Government Agencies ; Models, Biological ; Northwestern United States ; Population Dynamics ; *Salmon/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2000-10-29
    Description: The effects of climate variability on Pacific salmon abundance are uncertain because historical records are short and are complicated by commercial harvesting and habitat alteration. We use lake sediment records of delta15N and biological indicators to reconstruct sockeye salmon abundance in the Bristol Bay and Kodiak Island regions of Alaska over the past 300 years. Marked shifts in populations occurred over decades during this period, and some pronounced changes appear to be related to climatic change. Variations in salmon returns due to climate or harvesting can have strong impacts on sockeye nursery lake productivity in systems where adult salmon carcasses are important nutrient sources.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finney, B P -- Gregory-Eaves, I -- Sweetman, J -- Douglas, M S -- Smol, J P -- New York, N.Y. -- Science. 2000 Oct 27;290(5492):795-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK 99775, USA. finney@ims.uaf.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11052941" target="_blank"〉PubMed〈/a〉
    Keywords: Alaska ; Animals ; *Climate ; Diatoms ; *Ecosystem ; Fisheries ; Fresh Water ; Geologic Sediments/chemistry ; Industry ; Nitrogen Isotopes/analysis ; Pacific Ocean ; Plankton ; Salmon/*physiology ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 10
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-07-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zimmer, C -- New York, N.Y. -- Science. 2001 Jul 27;293(5530):627-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11474097" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Cnidaria ; *Ecosystem ; Eutrophication ; Fisheries ; International Cooperation ; Israel ; Jordan ; Marine Biology ; Oceans and Seas ; Time Factors ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-08-07
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ajayi, Thomas -- Sherman, Kenneth -- Tang, Qisheng -- New York, N.Y. -- Science. 2002 Aug 2;297(5582):772.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12162321" target="_blank"〉PubMed〈/a〉
    Keywords: Biomass ; Conservation of Natural Resources/*economics/*methods/trends ; *Ecosystem ; Europe ; Fisheries ; International Cooperation ; *Marine Biology/economics/trends ; North America ; Water Pollution/prevention & control
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 12
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-02-24
    Description: Using a novel technique, described on page 795, paleoceanographers have been able to chart the abundance of sockeye salmon in the Bristol Bay and Kodiak Island regions of Alaska over the past 300 years--by far the most complete record yet. Through time, they found, sockeye populations have alternately soared and slipped, following natural climate variations--well before commercial fishers began throwing nets over the sides of boats.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brown, K -- New York, N.Y. -- Science. 2000 Oct 27;290(5492):685-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11184190" target="_blank"〉PubMed〈/a〉
    Keywords: Alaska ; Animals ; *Climate ; *Ecosystem ; Fisheries ; Fresh Water ; Geologic Sediments/chemistry ; Nitrogen Isotopes/analysis ; Pacific Ocean ; Salmon/*physiology ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
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  • 13
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2000-05-08
    Description: Fish faunas across the continental United States have become more similar through time because of widespread introductions of a group of cosmopolitan species intended to enhance food and sport fisheries. On average, pairs of states have 15.4 more species in common now than before European settlement of North America. The 89 pairs of states that formerly had no species in common now share an average of 25.2 species. Introductions have played a larger role than extirpations in homogenizing fish faunas. Western and New England states have received the most introductions, which is a reflection of the small number of native fishes in these areas considered desirable gamefish by settlers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rahel, F J -- New York, N.Y. -- Science. 2000 May 5;288(5467):854-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA. frahel@uwyo.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10797007" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Ecosystem ; Fisheries ; *Fishes ; Species Specificity ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
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  • 14
    Publication Date: 2001-08-18
    Description: The deployment of electronic data storage tags that are surgically implanted or satellite-linked provides marine researchers with new ways to examine the movements, environmental preferences, and physiology of pelagic vertebrates. We report the results obtained from tagging of Atlantic bluefin tuna with implantable archival and pop-up satellite archival tags. The electronic tagging data provide insights into the seasonal movements and environmental preferences of this species. Bluefin tuna dive to depths of 〉1000 meters and maintain a warm body temperature. Western-tagged bluefin tuna make trans-Atlantic migrations and they frequent spawning grounds in the Gulf of Mexico and eastern Mediterranean. These data are critical for the future management and conservation of bluefin tuna in the Atlantic.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Block, B A -- Dewar, H -- Blackwell, S B -- Williams, T D -- Prince, E D -- Farwell, C J -- Boustany, A -- Teo, S L -- Seitz, A -- Walli, A -- Fudge, D -- New York, N.Y. -- Science. 2001 Aug 17;293(5533):1310-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Tuna Research and Conservation Center, Stanford University, Hopkins Marine Station, Oceanview Boulevard, Pacific Grove, CA 93950, USA. bblock@stanford.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11509729" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Identification Systems ; Animals ; Atlantic Ocean ; *Behavior, Animal ; Body Temperature ; Conservation of Natural Resources ; Diving ; *Ecosystem ; Female ; Fisheries ; Male ; Reproduction ; Seasons ; Swimming ; Temperature ; Tuna/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 15
    Publication Date: 2003-07-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sanchirico, James N -- Stoffle, Richard -- Broad, Kenny -- Talaue-McManus, Liana -- New York, N.Y. -- Science. 2003 Jul 4;301(5629):47-9; author reply 47-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12843376" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; California ; *Conservation of Natural Resources ; *Ecosystem ; Fisheries ; *Fishes ; Humans ; Seawater
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 16
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-04-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Service, Robert F -- New York, N.Y. -- Science. 2003 Apr 4;300(5616):36-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12677035" target="_blank"〉PubMed〈/a〉
    Keywords: Agriculture ; Animals ; California ; *Conservation of Natural Resources ; *Cypriniformes/physiology ; *Ecology ; Ecosystem ; Environment ; Fisheries ; *Fresh Water ; Government Agencies ; National Academy of Sciences (U.S.) ; *Oncorhynchus kisutch/physiology ; Oregon ; United States ; Water Movements
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
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  • 17
    Publication Date: 2004-11-13
    Description: The multibillion-dollar trade in bushmeat is among the most immediate threats to the persistence of tropical vertebrates, but our understanding of its underlying drivers and effects on human welfare is limited by a lack of empirical data. We used 30 years of data from Ghana to link mammal declines to the bushmeat trade and to spatial and temporal changes in the availability of fish. We show that years of poor fish supply coincided with increased hunting in nature reserves and sharp declines in biomass of 41 wildlife species. Local market data provide evidence of a direct link between fish supply and subsequent bushmeat demand in villages and show bushmeat's role as a dietary staple in the region. Our results emphasize the urgent need to develop cheap protein alternatives to bushmeat and to improve fisheries management by foreign and domestic fleets to avert extinctions of tropical wildlife.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brashares, Justin S -- Arcese, Peter -- Sam, Moses K -- Coppolillo, Peter B -- Sinclair, A R E -- Balmford, Andrew -- New York, N.Y. -- Science. 2004 Nov 12;306(5699):1180-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Conservation Biology Group, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK. brashares@nature.berkeley.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15539602" target="_blank"〉PubMed〈/a〉
    Keywords: Agriculture ; Animals ; *Animals, Wild ; Biodiversity ; Biomass ; Commerce ; Conservation of Natural Resources ; Fisheries ; *Fishes ; *Food Supply ; Ghana ; Humans ; *Mammals ; *Meat ; Population Density ; Population Dynamics
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-08-31
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grimm, David -- New York, N.Y. -- Science. 2004 Aug 27;305(5688):1235.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15333821" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biodiversity ; *Ecosystem ; Fisheries ; *Fishes ; Humans ; Population Density ; *Recreation ; United States
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  • 19
    Publication Date: 2004-09-14
    Description: It is now widely accepted that global warming is occurring, yet its effects on the world's largest ecosystem, the marine pelagic realm, are largely unknown. We show that sea surface warming in the Northeast Atlantic is accompanied by increasing phytoplankton abundance in cooler regions and decreasing phytoplankton abundance in warmer regions. This impact propagates up the food web (bottom-up control) through copepod herbivores to zooplankton carnivores because of tight trophic coupling. Future warming is therefore likely to alter the spatial distribution of primary and secondary pelagic production, affecting ecosystem services and placing additional stress on already-depleted fish and mammal populations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Richardson, Anthony J -- Schoeman, David S -- New York, N.Y. -- Science. 2004 Sep 10;305(5690):1609-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sir Alister Hardy Foundation for Ocean Science, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK. anr@sahfos.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15361622" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atlantic Ocean ; *Climate ; Copepoda/*growth & development ; *Ecosystem ; Fisheries ; Fishes ; *Food Chain ; Greenhouse Effect ; Meta-Analysis as Topic ; Phytoplankton/*growth & development ; Population Dynamics ; Seawater ; Temperature ; Zooplankton/*growth & development
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-08-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Proffitt, Fiona -- New York, N.Y. -- Science. 2004 Aug 20;305(5687):1090.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15326320" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Birds/*physiology ; *Ecosystem ; *Eels ; Fisheries ; Food Chain ; North Sea ; Plankton ; Population Density ; *Reproduction ; Scotland ; Seawater ; Temperature
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-06-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wright, Bruce A -- Okey, Thomas A -- New York, N.Y. -- Science. 2004 Jun 25;304(5679):1903.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15218125" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Conservation of Natural Resources ; *Ecosystem ; *Environment ; Fisheries ; Humans ; Information Dissemination ; Population Growth ; Public Policy
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-08-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Allison, Edward H -- Seeley, Janet A -- New York, N.Y. -- Science. 2004 Aug 20;305(5687):1104.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15326332" target="_blank"〉PubMed〈/a〉
    Keywords: Asia/epidemiology ; Female ; Fisheries ; HIV Infections/*epidemiology/transmission ; Humans ; Male ; Occupations ; Prevalence ; Sexual Partners ; *Transients and Migrants
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 23
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-05-10
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zimmer, Carl -- New York, N.Y. -- Science. 2003 May 9;300(5621):895.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12738833" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Breeding ; *Conservation of Natural Resources ; Environment ; Fisheries ; *Fishes/genetics/growth & development/physiology ; Plant Development ; Reproduction ; *Selection, Genetic ; Sexual Maturation
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 24
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-07-27
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rembold, Christopher M -- New York, N.Y. -- Science. 2004 Jul 23;305(5683):475; author reply 475.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15273376" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Coronary Artery Disease/mortality/*prevention & control ; *Diet ; Environmental Pollutants/toxicity ; Fatty Acids, Omega-3/*administration & dosage ; Fisheries ; *Food Contamination ; Humans ; Neoplasms/chemically induced/epidemiology ; Randomized Controlled Trials as Topic ; Risk Assessment ; *Salmon ; Toxicity Tests
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 25
    Publication Date: 2004-09-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stokstad, Erik -- New York, N.Y. -- Science. 2004 Sep 10;305(5690):1548-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15361593" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atlantic Ocean ; *Climate ; *Ecosystem ; Fisheries ; *Food Chain ; Phytoplankton/*growth & development ; Population Dynamics ; Seawater ; Temperature ; Zooplankton/*growth & development
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 26
    Publication Date: 2002-12-10
    Description: There is debate concerning the most effective conservation of marine biodiversity, especially regarding the appropriate location, size, and connectivity of marine reserves. We describe a means of establishing marine reserve networks by using optimization algorithms and multiple levels of information on biodiversity, ecological processes (spawning, recruitment, and larval connectivity), and socioeconomic factors in the Gulf of California. A network covering 40% of rocky reef habitat can fulfill many conservation goals while reducing social conflict. This quantitative approach provides a powerful tool for decision-makers tasked with siting marine reserves.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sala, Enric -- Aburto-Oropeza, Octavio -- Paredes, Gustavo -- Parra, Ivan -- Barrera, Juan C -- Dayton, Paul K -- New York, N.Y. -- Science. 2002 Dec 6;298(5600):1991-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, La Jolla, CA 92093, USA. esala@ucsd.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12471258" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; California ; Computer Simulation ; *Conservation of Natural Resources ; *Ecosystem ; Environment ; Fisheries ; Fishes ; Invertebrates ; *Models, Biological ; *Seawater
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 27
    Publication Date: 2003-08-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Webster, Paul -- New York, N.Y. -- Science. 2003 Aug 29;301(5637):1167.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12947169" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Conservation of Natural Resources/economics ; *Ecosystem ; *Environment ; Financial Support ; Fisheries ; Fresh Water ; Pacific Ocean ; Russia ; *Salmon ; United Nations/economics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 28
    Publication Date: 2004-12-03
    Description: Photovoltaic (PV) systems (cells and arrays) for spacecraft power have become an international market. This market demands accurate prediction of the solar array power output in space throughout the mission life of the spacecraft. Since the beginning of space flight, space-faring nations have independently developed methods to calibrate solar cells for power output in low Earth orbit (LEO). These methods rely on terrestrial, laboratory, or extraterrestrial light sources to simulate or approximate the air mass zero (AM0) solar intensity and spectrum.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 101-104; NASA/CP-2002-211831
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  • 29
    Publication Date: 2004-12-03
    Description: Laser-based combustion diagnostics, such as single-pulse UV Raman spectroscopy and visible Raman spectroscopy, have been successfully applied to optically-accessible rocket-like test articles. If an independent pressure measurement is available, Raman major species concentration measurements can also provide a temperature measurement. However it is desirable to obtain a Raman-derived temperature measurement without the need for simultaneous pressure measurement, especially when chamber pressure may vary spatially. This report describes Raman temperature measurements obtained by exploiting the variation in shape of the H2 Raman spectrum. Hydrogen is advantageous since it is ubiquitous in H2-O2 systems and its Raman spectrum is simpler than for other diatomics. However the influence of high pressure on the H2 Raman spectrum must be investigated. At moderate pressures, well below those of rocket engines, the Raman spectra of O2 and N2 are known to become featureless due to collisional broadening.
    Keywords: Spacecraft Propulsion and Power
    Type: Research Reports: 2001 NASA/ASEE Summer Faculty Fellowship Program; LII-1 - LII-5; NASA/CR-2002-211840
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  • 30
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    In:  CASI
    Publication Date: 2004-10-30
    Description: Europa is the only body in the solar system besides Mars that is currently viewed as a body of significant interest relative to the process of chemical evolution and/or the origin of life or for which scientific opinion provides a significant chance of contamination which could jeopardize a future biological experiment. Thus, both NASA and COSPAR policy require that Europa be protected from biological contamination that could result from scientific exploration conducted by robotic spacecraft. In 2000, the Task Group on the Forward Contamination of Europa (Space Studies Board) published its report on Preventing the Forward Contamination of Europa recommending a limit of 10(exp -4) probability of contamination of Europa's ocean per mission (at any time in the future) by a single viable terrestrial microbe. While NASA guidelines do not yet explicitly reflect this new recommendation, it is likely that the SSB recommendation will be adopted by NASA planetary protection in the form of a sterility requirement or at least a stringent total microbial burden requirement. In our presentation, we will present an overview of the anticipated planetary protection requirements for both orbiters and landers destined for Europa and some of the challenges these requirements will present.
    Keywords: Spacecraft Propulsion and Power
    Type: Forum on Concepts and Approaches for Jupiter Icy Moons Orbiter; 40; LPI-Contrib-1163
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  • 31
    Publication Date: 2004-12-03
    Description: Computational Fluid Dynamics (CFD) has considerably evolved in the last decade. There are many computer programs that can perform computations on viscous internal or external flows with chemical reactions. CFD has become a commonly used tool in the design and analysis of gas turbines, ramjet combustors, turbo-machinery, inlet ducts, rocket engines, jet interaction, missile, and ramjet nozzles. One of the problems of interest to NASA has always been the performance prediction for rocket and air-breathing engines. Due to the complexity of flow in these engines it is necessary to resolve the flowfield into a fine mesh to capture quantities like turbulence and heat transfer. However, calculation on a high-resolution grid is associated with a prohibitively increasing computational time that can downgrade the value of the CFD for practical engineering calculations. The Liquid Thrust Chamber Performance (LTCP) code was developed for NASA/MSFC (Marshall Space Flight Center) to perform liquid rocket engine performance calculations. This code is a 2D/axisymmetric full Navier-Stokes (NS) solver with fully coupled finite rate chemistry and Eulerian treatment of liquid fuel and/or oxidizer droplets. One of the advantages of this code has been the resemblance of its input file to the JANNAF (Joint Army Navy NASA Air Force Interagency Propulsion Committee) standard TDK code, and its automatic grid generation for JANNAF defined combustion chamber wall geometry. These options minimize the learning effort for TDK users, and make the code a good candidate for performing engineering calculations. Although the LTCP code was developed for liquid rocket engines, it is a general-purpose code and has been used for solving many engineering problems. However, the single zone formulation of the LTCP has limited the code to be applicable to problems with complex geometry. Furthermore, the computational time becomes prohibitively large for high-resolution problems with chemistry, two-equation turbulence model, and two-phase flow. To overcome these limitations, the LTCP code is rewritten to include the multi-zone capability with domain decomposition that makes it suitable for parallel processing, i.e., enabling the code to run every zone or sub-domain on a separate processor. This can reduce the run time by a factor of 6 to 8, depending on the problem.
    Keywords: Spacecraft Propulsion and Power
    Type: Research Reports: 2001 NASA/ASEE Summer Faculty Fellowship Program; XXXV-1 - XXXV-5; NASA/CR-2002-211840
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  • 32
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    In:  CASI
    Publication Date: 2004-12-03
    Description: The tools and techniques of three-dimensional computer imaging and animation are more than just a bag of new tricks. They have the power to communicate, inspire, and move the minds of people. Through these animations, it is the intent of the author to help the Propulsion Research Center educate and inspire the public about the vast possibilities of space exploration using Fission Electric Propulsion systems.
    Keywords: Spacecraft Propulsion and Power
    Type: Research Reports: 2001 NASA/ASEE Summer Faculty Fellowship Program; XXVIII-1 - XXVIII-5; NASA/CR-2002-211840
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  • 33
    Publication Date: 2004-12-03
    Description: This document explores the use of advanced computer technologies with an emphasis on object-oriented design to be applied in the development of software for a rocket engine to improve vehicle safety and reliability. The primary focus is on phase one of this project, the smart start sequence module. The objectives are: 1) To use current sound software engineering practices, object-orientation; 2) To improve on software development time, maintenance, execution and management; 3) To provide an alternate design choice for control, implementation, and performance.
    Keywords: Spacecraft Propulsion and Power
    Type: Research Reports: 2001 NASA/ASEE Summer Faculty Fellowship Program; V-1 - V-22; NASA/CR-2002-211840
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  • 34
    facet.materialart.
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    In:  CASI
    Publication Date: 2004-12-03
    Description: Magnetized target fusion (MTF) is under consideration as a means of building a low mass, high specific impulse, and high thrust propulsion system for interplanetary travel. This unique combination is the result of the generation of a high temperature plasma by the nuclear fusion process. This plasma can then be deflected by magnetic fields to provide thrust. Fusion is initiated by a small traction of the energy generated in the magnetic coils due to the plasma's compression of the magnetic field. The power gain from a fusion reaction is such that inefficiencies due to thermal neutrons and coil losses can be overcome. Since the fusion reaction products are directly used for propulsion and the power to initiate the reaction is directly obtained from the thrust generation, no massive power supply for energy conversion is required. The result should be a low engine mass, high specific impulse and high thrust system. The key is to successfully initiate fusion as a proof-of-principle for this application. Currently MSFC is implementing MTF proof-of-principle experiments. This involves many technical details and ancillary investigations. Of these, selected pertinent issues include the properties, orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the target plasma's behavior under compression and the convergence and mixing of the gun plasma are under investigation. This work is to focus on the gun characterization and development as it relates to plasma initiation and repeatability.
    Keywords: Spacecraft Propulsion and Power
    Type: Research Reports: 2001 NASA/ASEE Summer Faculty Fellowship Program; XVIII-1 - XVIII-6; NASA/CR-2002-211840
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  • 35
    Publication Date: 2011-08-23
    Description: The development of rocket based combined cycle (RBCC) engines are highly dependent upon integrating several different modes of operation into a single system. Due to the integrated nature of the propulsion system, each operating mode relies on the same expansion system to provide thrust. A fixed geometry, altitude-compensating aft-expansion configuration is used for the GTX flowpath configuration. Initial studies on the GTX expansion designs have demonstrated the importance of a smooth, highly integrated design for propulsion system performance. Based upon the results from the initial studies, further design improvements were made to the expansion system. Nozzles designed based on both conical and streamline traced flowfields; are discussed. Results from 3-D CFD calculations on an optimized geometry are also presented. A series of cold-flow experiments are proposed to validate the CFD analysis and quantify performance of the flowpath expansions surface design. A discussion is provided of the research hardware designs and experimental test plans.
    Keywords: Spacecraft Propulsion and Power
    Type: 26th JANNAF Airbreathing Propulsion Subcommittee Meeting; Volume 1; 271-279; CPIA-Publ-713-Vol-1
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  • 36
    Publication Date: 2011-08-23
    Description: Rapid transport of large payloads and human crews throughout the solar system requires propulsion systems having very high specific impulse (I(sub sp) 〉 10(exp 4) to 10(exp 5) s). It also calls for systems with extremely low mass-power ratios (alpha 〈 10(exp -1) kg/kW). Such low alpha are beyond the reach of conventional power-limited propulsion, but may be attainable with fusion and other nuclear concepts that produce energy within the propellant. The magnitude of energy gain must be large enough to sustain the nuclear process while still providing a high jet power relative to the massive energy-intensive subsystems associated with these concepts. This paper evaluates the impact of energy gain and subsystem characteristics on alpha. Central to the analysis are general parameters that embody the essential features of any 'gain-limited' propulsion power balance. Results show that the gains required to achieve alpha = 10(exp -1) kg/kW with foreseeable technology range from approximately 100 to over 2000, which is three to five orders of magnitude greater than current fusion state of the arL Sensitivity analyses point to the parameters exerting the most influence for either: (1) lowering a and improving mission performance or (2) relaxing gain requirements and reducing demands on the fusion process. The greatest impact comes from reducing mass and increasing efficiency of the thruster and subsystems downstream of the fusion process. High relative gain, through enhanced fusion processes or more efficient drivers and processors, is also desirable. There is a benefit in improving driver and subsystem characteristics upstream of the fusion process, but it diminishes at relative gains 〉 100.
    Keywords: Spacecraft Propulsion and Power
    Type: Journal of Propulsion and Power; Volume 17; No. 5; 988-994
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  • 37
    Publication Date: 2013-08-31
    Description: This is a preliminary assessment of the applicability and spacecraft-level impact of using very lightweight thin-film solar arrays with relatively large deployed areas for representative Earth orbiting missions. The most and least attractive features of thin-film solar arrays are briefly discussed. A simple calculation is then presented illustrating that from a solar array alone mass perspective, larger arrays with less efficient but lighter thin-film solar cells can weigh less than smaller arrays with more efficient but heavier crystalline cells. However, a proper spacecraft-level systems assessment must take into account the additional mass associated with solar array deployed area: the propellant needed to desaturate the momentum accumulated from area-related disturbance torques and to perform aerodynamic drag makeup reboost. The results for such an assessment are presented for a representative low Earth orbit (LEO) mission, as a function of altitude and mission life, and a geostationary Earth orbit (GEO) mission. Discussion of the results includes a list of specific mission types most likely to benefit from using thin-film arrays. NASA Glenn's low-temperature approach to depositing thin-film cells on lightweight, flexible plastic substrates is also briefly discussed to provide a perspective on one approach to achieving this enabling technology. The paper concludes with a list of issues to be addressed prior to use of thin-film solar arrays in space and the observation that with their unique characteristics, very lightweight arrays using efficient, thin-film cells on flexible substrates may become the best array option for a subset of Earth orbiting missions.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 74-83; NASA/CP-2002-211831
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  • 38
    Publication Date: 2013-08-31
    Description: While monolithic multi-junction cells are preferred for flat plate arrays, mechanically stacked multi-junction cells are superior for solar concentrator applications. Reasons for this are that the mechanical stacked configuration with high efficiency Gallium Antimonide cells allows utilization of a much wider range of the solar energy spectrum, and the ability to use voltage matched interconnects results in full use of low bandgap cell currents. Herein, data are presented for simple two terminal voltage-matched circuits using InGaP/GaAs/GaSb stacked cells showing 34% average circuit efficiency for a lot of 12 circuits given prismatic covers. These circuits have been designed to fit into the ultralight Stretched Lens Array being developed by NASA. With these new cell-interconnected-circuits, we project that the power density at GEO operating temperature can be increased from 296 W/m2 to 350 W/m2 while maintaining the specific power at 190 W/kg at the full wing level.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 24-31; NASA/CP-2002-211831
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  • 39
    facet.materialart.
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    In:  CASI
    Publication Date: 2013-08-31
    Description: This custom bibliography from the NASA Scientific and Technical Information Program lists a sampling of records found in the NASA Aeronautics and Space Database. The scope of this topic includes primarily nuclear thermal and nuclear electric technologies, to enable spacecraft and instrument operation and communications, particularly in the outer solar system, where sunlight can no longer be exploited by solar panels. This area of focus is one of the enabling technologies as defined by NASA s Report of the President s Commission on Implementation of United States Space Exploration Policy, published in June 2004.
    Keywords: Spacecraft Propulsion and Power
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  • 40
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    In:  CASI
    Publication Date: 2016-06-07
    Description: A rocket engine gas generator component development test was recently conducted at the Marshall Space Flight Center. This gas generator is intended to power a rocket engine turbopump by the combustion of Lox and RP-1. The testing demonstrated design requirements for start sequence, wall compatibility, performance, and stable combustion. During testing the gas generator injector was modified to improve distribution of outer wall coolant and the igniter boss was modified to investigate the use of a pyrotechnic igniter. Expected chamber pressure oscillations at longitudinal acoustic mode were measured for three different chamber lengths tested. High amplitude discrete oscillations resulted in the chamber-alone configurations when chamber acoustic modes coupled with feed-system acoustics modes. For the full gas generator configuration, which included a turbine inlet manifold, high amplitude oscillations occurred only at off-design very low power levels. This testing led to a successful gas generator design for the Fastrac 60,000 lb thrust engine.
    Keywords: Spacecraft Propulsion and Power
    Type: The Tenth Thermal and Fluids Analysis Workshop; NASA/CP-2001-211141
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  • 41
    Publication Date: 2016-06-07
    Description: Propellant injector development at MSFC includes experimental analysis using optical techniques, such as Raman, fluorescence, or Mie scattering. For the application of spontaneous Raman scattering to hydrocarbon-fueled flows a technique needs to be developed to remove the interfering polycyclic aromatic hydrocarbon fluorescence from the relatively weak Raman signals. A current application of such a technique is to the analysis of the mixing and combustion performance of multijet, impinging-jet candidate fuel injectors for the baseline Mars ascent engine, which will burn methane and liquid oxygen produced in-situ on Mars to reduce the propellant mass transported to Mars for future manned Mars missions. The present technique takes advantage of the strongly polarized nature of Raman scattering. It is shown to be discernable from unpolarized fluorescence interference by subtracting one polarized image from another. Both of these polarized images are obtained from a single laser pulse by using a polarization-separating calcite rhomb mounted in the imaging spectrograph. A demonstration in a propane-air flame is presented.
    Keywords: Spacecraft Propulsion and Power
    Type: The Tenth Thermal and Fluids Analysis Workshop; NASA/CP-2001-211141
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  • 42
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: This paper will describe the thermal analysis techniques used to predict temperatures in the film-cooled ablative rocket nozzle used on the Fastrac 60K rocket engine. A model was developed that predicts char and pyrolysis depths, liner thermal gradients, and temperatures of the bondline between the overwrap and liner. Correlation of the model was accomplished by thermal analog tests performed at Southern Research, and specially instrumented hot fire tests at the Marshall Space Flight Center. Infrared thermography was instrumental in defining nozzle hot wall surface temperatures. In-depth and outboard thermocouple data was used to correlate the kinetic decomposition routine used to predict char and pyrolysis depths. These depths were anchored with measured char and pyrolysis depths from cross-sectioned hot-fire nozzles. For the X-34 flight analysis, the model includes the ablative Thermal Protection System (TPS) material that protects the overwrap from the recirculating plume. Results from model correlation, hot-fire testing, and flight predictions will be discussed.
    Keywords: Spacecraft Propulsion and Power
    Type: The Tenth Thermal and Fluids Analysis Workshop; NASA/CP-2001-211141
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  • 43
    Publication Date: 2016-06-07
    Description: This study provides for development and test verification of a thermal model used for prediction of joint heating environments, structural temperatures and seal erosions in the Space Shuttle Reusable Solid Rocket Motor (RSRM) Nozzle Joint-4. The heating environments are a result of rapid pressurization of the joint free volume assuming a leak path has occurred in the filler material used for assembly gap close out. Combustion gases flow along the leak path from nozzle environment to joint O-ring gland resulting in local heating to the metal housing and erosion of seal materials. Analysis of this condition was based on usage of the NASA Joint Pressurization Routine (JPR) for environment determination and the Systems Improved Numerical Differencing Analyzer (SINDA) for structural temperature prediction. Model generated temperatures, pressures and seal erosions are compared to hot fire test data for several different leak path situations. Investigated in the hot fire test program were nozzle joint-4 O-ring erosion sensitivities to leak path width in both open and confined joint geometries. Model predictions were in generally good agreement with the test data for the confined leak path cases. Worst case flight predictions are provided using the test-calibrated model. Analysis issues are discussed based on model calibration procedures.
    Keywords: Spacecraft Propulsion and Power
    Type: The Tenth Thermal and Fluids Analysis Workshop; NASA/CP-2001-211141
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  • 44
    Publication Date: 2016-06-07
    Description: The tasks outlined in this viewgraph presentation on safe life propulsion design technologies (third generation propulsion research and technology) include the following: (1) Ceramic matrix composite (CMC) life prediction methods; (2) Life prediction methods for ultra high temperature polymer matrix composites for reusable launch vehicle (RLV) airframe and engine application; (3) Enabling design and life prediction technology for cost effective large-scale utilization of MMCs and innovative metallic material concepts; (4) Probabilistic analysis methods for brittle materials and structures; (5) Damage assessment in CMC propulsion components using nondestructive characterization techniques; and (6) High temperature structural seals for RLV applications.
    Keywords: Spacecraft Propulsion and Power
    Type: ST Day 2000: Risk Reduction for The Next Generations
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  • 45
    Publication Date: 2016-06-07
    Description: The Science Laboratory operated by GB Tech was tasked by the Environmental Office at the NASA Marshall Space Flight Center (MSFC) to collect rocket plume samples and to measure gaseous components and airborne particulates from the hot test firings of the Atlas III/RD 180 test article at MSFC. This data will be used to validate plume prediction codes and to assess environmental air quality issues.
    Keywords: Spacecraft Propulsion and Power
    Type: Proceedings of The 4th Conference on Aerospace Materials, Processes, and Environmental Technology; NASA/CP-2001-210427
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  • 46
    Publication Date: 2016-06-07
    Description: In this viewgraph presentation, IMWG (IHPRPT Materials Working Group) government and industry members, together with the IHPRPT (Integrated High Payoff Rocket Propulsion Technologies Program Material Development Plan) National Component Leads, have developed a materials plan to address the critical needs of the IHPRPT community: (1) liquids boost and orbit transfer; (2) solids boost and orbit transfer; (3) tactical propulsion; and (4) spacecraft propulsion. Criticality of materials' role in achieving IHPRPT goals is evidenced by the significant investment over the next five years.
    Keywords: Spacecraft Propulsion and Power
    Type: Proceedings of the 4th Conference on Aerospace Materials, Processes, and Environmental Technology; NASA/CP-2001-210427
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  • 47
    Publication Date: 2015-05-11
    Description: The Analysis and Management branch of the Power and Propulsion Office at NASA Glenn Research Center is responsible for performing complex analyses of the space power and In-Space propulsion products developed by GRC. This work quantifies the benefits of the advanced technologies to support on-going advocacy efforts. The Power and Propulsion Office is committed to understanding how the advancement in space technologies could benefit future NASA missions. They support many diverse projects and missions throughout NASA as well as industry and academia. The area of work that we are concentrating on is space technology investment strategies. Our goal is to develop a Monte-Carlo based tool to investigate technology impacts in space electric power systems. The framework is being developed at this stage, which will be used to set up a computer simulation of a space electric power system (EPS). The outcome is expected to be a probabilistic assessment of critical technologies and potential development issues. We are developing methods for integrating existing spreadsheet-based tools into the simulation tool. Also, work is being done on defining interface protocols to enable rapid integration of future tools. Monte Carlo-based simulation programs for statistical modeling of the EPS Model. I decided to learn and evaluate Palisade's @Risk and Risk Optimizer software, and utilize it's capabilities for the Electric Power System (EPS) model. I also looked at similar software packages (JMP, SPSS, Crystal Ball, VenSim, Analytica) available from other suppliers and evaluated them. The second task was to develop the framework for the tool, in which we had to define technology characteristics using weighing factors and probability distributions. Also we had to define the simulation space and add hard and soft constraints to the model. The third task is to incorporate (preliminary) cost factors into the model. A final task is developing a cross-platform solution of this framework.
    Keywords: Spacecraft Propulsion and Power
    Type: Research Symposium II
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  • 48
    Publication Date: 2013-08-24
    Description: The design of a single-stage-to-orbit air breathing propulsion system requires the simultaneous development of a reference launch vehicle in order to achieve the optimal mission performance. Accordingly, for the GTX study a 300-lb payload reference vehicle was preliminary sized to a gross liftoff weight (GLOW) of 238,000 lb. A finite element model of the integrated vehicle/propulsion system was subjected to the trajectory environment and subsequently optimized for structural efficiency. This study involved the development of aerodynamic loads mapped to finite element models of the integrated system in order to assess vehicle margins of safety. Commercially available analysis codes were used in the process along with some internally developed spread-sheets and FORTRAN codes specific to the GTX geometry for mapping of thermal and pressure loads. A mass fraction of 0.20 for the integrated system dry weight has been the driver for a vehicle design consisting of state-of-the-art composite materials in order to meet the rigid weight requirements. This paper summarizes the methodology used for preliminary analyses and presents the current status of the weight optimization for the structural components of the integrated system.
    Keywords: Spacecraft Propulsion and Power
    Type: 26th JANNAF Airbreathing Propulsion Subcommittee Meeting; Volume 1; 291-303; CPIA-Publ-713-Vol-1
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  • 49
    Publication Date: 2013-08-29
    Description: Solar-thermal propulsion is a concept for producing thrust sufficient for orbital transfers and requires innovative, lightweight structures. This note presents a description of an inflatable concentrator that consists of a torus, lens simulator, and three tapered struts. Modal testing was discussed for characterization and verification of the solar concentrator assembly. Finite element shell models of the concentrator were developed using a two-step nonlinear approach, and results were compared to test data. Reasonable model-to-test agreement was achieved for the torus, and results for the concentrator assembly were comparable to the test for several modes.
    Keywords: Spacecraft Propulsion and Power
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  • 50
    Publication Date: 2013-08-29
    Description: Modern computational and experimental tools for aerodynamics and propulsion applications have matured to a stage where they can provide substantial insight into engineering processes involving fluid flows, and can be fruitfully utilized to help improve the design of practical devices. In particular, rapid and continuous development in aerospace engineering demands that new design concepts be regularly proposed to meet goals for increased performance, robustness and safety while concurrently decreasing cost. To date, the majority of the effort in design optimization of fluid dynamics has relied on gradient-based search algorithms. Global optimization methods can utilize the information collected from various sources and by different tools. These methods offer multi-criterion optimization, handle the existence of multiple design points and trade-offs via insight into the entire design space, can easily perform tasks in parallel, and are often effective in filtering the noise intrinsic to numerical and experimental data. However, a successful application of the global optimization method needs to address issues related to data requirements with an increase in the number of design variables, and methods for predicting the model performance. In this article, we review recent progress made in establishing suitable global optimization techniques employing neural network and polynomial-based response surface methodologies. Issues addressed include techniques for construction of the response surface, design of experiment techniques for supplying information in an economical manner, optimization procedures and multi-level techniques, and assessment of relative performance between polynomials and neural networks. Examples drawn from wing aerodynamics, turbulent diffuser flows, gas-gas injectors, and supersonic turbines are employed to help demonstrate the issues involved in an engineering design context. Both the usefulness of the existing knowledge to aid current design practices and the need for future research are identified.
    Keywords: Spacecraft Propulsion and Power
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  • 51
    Publication Date: 2013-08-29
    Description: Micro-electromechanical systems (MEMS) techniques offer great potential in satisfying the mission requirements for the next generation of "micro-scale" satellites being designed by NASA and Department of Defense agencies. More commonly referred to as "nanosats", these miniature satellites feature masses in the range of 10-100 kg and therefore have unique propulsion requirements. The propulsion systems must be capable of providing extremely low levels of thrust and impulse while also satisfying stringent demands on size, mass, power consumption and cost. We begin with an overview of micropropulsion requirements and some current MEMS-based strategies being developed to meet these needs. The remainder of the article focuses the progress being made at NASA Goddard Space Flight Center towards the development of a prototype monopropellant MEMS thruster which uses the catalyzed chemical decomposition of high concentration hydrogen peroxide as a propulsion mechanism. The products of decomposition are delivered to a micro-scale converging/diverging supersonic nozzle which produces the thrust vector; the targeted thrust level approximately 500 N with a specific impulse of 140-180 seconds. Macro-scale hydrogen peroxide thrusters have been used for satellite propulsion for decades; however, the implementation of traditional thruster designs on a MEMS scale has uncovered new challenges in fabrication, materials compatibility, and combustion and hydrodynamic modeling. A summary of the achievements of the project to date is given, as is a discussion of remaining challenges and future prospects.
    Keywords: Spacecraft Propulsion and Power
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  • 52
    Publication Date: 2013-08-31
    Description: A historical view of the research and development in photovoltaics from the perspective of both the terrestrial and the space communities is presented from the early days through the '70s and '80s and the '90s and beyond. The synergy of both communities in the beginning and once again in the present and hopefully future are highlighted, with examples of the important features in each program. The space community which was impressed by the light-weight and reliability of photovoltaics drove much of the early development. Even up to today, nearly every satellites and other scientific space probe that has been launched has included some solar power. However, since the cost of these power systems were only a small fraction of the satellite and launch cost, the use of much of this technology for the terrestrial marketplace was not feasible. It was clear that the focus of the terrestrial community would be best served by reducing costs. This would include addressing a variety of manufacturing issues and raising the rate of production. Success in these programs and a resulting globalization of effort resulted in major strides in the reduction of PV module costs and increased production. Although, the space community derived benefit from some of these advancements, its focus was on pushing the envelope with regard to cell efficiency. The gap between theoretical efficiencies and experimental efficiencies for silicon, gallium arsenide and indium phosphide became almost non-existent. Recent work by both communities have focused on the development thin film cells of amorphous silicon, CuInSe2 and CdTe. These cells hold the promise of lower costs for the terrestrial community as well as possible flexible substrates, better radiation resistance, and higher specific power for the space community. It is predicted that future trends in both communities will be directed toward advances through the application of nanotechnology. A picture is emerging in which the space and terrestrial solar cell communities shall once again share many common goals and, in fact, companies may manufacture both space and terrestrial solar cells in III-V materials and thin film materials. Basic photovoltaics research including these current trends in nanotechnology provides a valuable service for both worlds in that fundamental understanding of cell processes is still vitally important, particularly with new materials or new cell structures. It is entirely possible that one day we might have one solar array design that will meet the criteria for success in both space and on the Earth or perhaps the Moon or Mars.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 202-210; NASA/CP-2002-211831
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  • 53
    Publication Date: 2013-08-31
    Description: Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 C using the single source precursor (PPh3)2CuIn(SEt)4 in an argon atmosphere. The absorber ranges in thickness from 0.75 - 1.0 micrometers, and exhibits a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a (112) orientation. Schottky diodes prepared by thermal evaporation of aluminum contacts on to the CuInS2 yielded diodes for films that were annealed at 600 C. Solar cells were prepared using annealed films and had the (top down) composition of Al/ZnO/CdS/CuInS2/Mo/Glass. The Jsc, Voc, FF and (eta) were 6.46 mA per square centimeter, 307 mV, 24% and 0.35%, respectively for the best small area cells under simulated AM0 illumination.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 84-90; NASA/CP-2002-211831
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  • 54
    Publication Date: 2013-08-31
    Description: Real concerns of spacecraft charging and experience with solar array augmented electrostatic discharge arcs on spacecraft have minimized the use of high voltages on large solar arrays despite numerous vehicle system mass and efficiency advantages. Boeing's solar tile (patent pending) allows high voltage to be generated at the array without the mass and efficiency losses of electronic conversion. Direct drive electric propulsion and higher power payloads (lower spacecraft weight) will benefit from this design. As future power demand grows, spacecraft designers must use higher voltage to minimize transmission loss and power cable mass for very large area arrays. This paper will describe the design and discuss the successful test of Boeing's 500-Volt Solar Tile in NASA Glenn's Tenney chamber in the Space Plasma Interaction Facility. The work was sponsored by NASA's Space Solar Power Exploratory Research and Technology (SERT) Program and will result in updated high voltage solar array design guidelines being published.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 49-54; NASA/CP-2002-211831
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  • 55
    Publication Date: 2013-08-31
    Description: A high-performance, ultralight, photovoltaic concentrator array is being developed for space power. The stretched lens array (SLA) uses stretched-membrane, silicone Fresnel lenses to concentrate sunlight onto triple-junction photovoltaic cells. The cells are mounted to a composite radiator structure. The entire solar array wing, including lenses, photovoltaic cell flex circuits, composite panels, hinges, yoke, wiring harness, and deployment mechanisms, has a mass density of 1.6 kg/sq.m. NASA Glenn has measured 27.4% net SLA panel efficiency, or 375 W/sq.m. power density, at room temperature. At GEO operating cell temperature (80 C), this power density will be 300 W/sq.m., resulting in more than 180 W/kg specific power at the full wing level. SLA is a direct ultralight descendent of the successful SCARLET array on NASA's Deep Space 1 spacecraft. This paper describes the evolution from SCARLET to SLA, summarizes the SLA's key features, and provides performance and mass data for this new concentrator array.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 14-23; NASA/CP-2002-211831
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  • 56
    Publication Date: 2013-08-31
    Description: Future space nuclear power systems will require radiator technology to dissipate excess heat created by a nuclear reactor. Large radiator fins with circulating coolant are in development for this purpose and an investigation of how to make them most efficient is underway. Maximizing the surface area while minimizing the mass of such radiator fins is critical for obtaining the highest efficiency in dissipating heat. Processes to develop surface roughness are under investigation to maximize the effective surface area of a radiator fin. Surface roughness is created through several methods including oxidation and texturing. The effects of atomic oxygen impingement on carbon-carbon surfaces are currently being investigated for texturing a radiator surface. Early studies of atomic oxygen impingement in low Earth orbit indicate significant texturing due to ram atomic oxygen. The surface morphology of the affected surfaces shows many microscopic cones and valleys which have been experimentally shown to increase radiation emittance. Further study of this morphology proceeded in the Long Duration Exposure Facility (LDEF). Atomic oxygen experiments on the LDEF successfully duplicated the results obtained from materials in spaceflight by subjecting samples to 4.5 eV atomic oxygen from a fixed ram angle. These experiments replicated the conical valley morphology that was seen on samples subjected to low Earth orbit.
    Keywords: Spacecraft Propulsion and Power
    Type: Interm Summary Reports
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  • 57
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The amount of chemical propellant required to accomplish certain NASA s planned missions is too immense such that the spacecraft will never be able to lift off. To address this concern, electric propulsion systems have been chosen as the primary propulsion systems for some NASA s future missions, including DAWN and JIMO. Research Center is a proposed engine for the JIMO mission, which will visit three of Jupiter s icy moons. Optimizing thruster s lifetime and efficiency are the two foci for the engineers on the Ion Team. One qualitative study of the engine s efficiency can be accomplished by examining the ratio of doubly- to singly-charged ions in the ion beam of the engine. Thrust efficiency directly relates to this ratio. The bulk of this project is to redesign and build an EXB probe to obtain this qualitative measurement. Once this probe is built, it can be installed in a vacuum tank (VF 65 in building 301) behind the exit plane of the HiPEP engine to collect data. Current chemical propulsion technology cannot address the needs of some deep space The HiPEP (High Power Electric Propulsion) engine being developed at NASA Glenn Research Center is a proposed engine for the JIMO mission, which will visit three Jupiter's icy moons.
    Keywords: Spacecraft Propulsion and Power
    Type: Interm Summary Reports; 5
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  • 58
    Publication Date: 2013-08-31
    Description: This custom bibliography from the NASA Scientific and Technical Information Program lists a sampling of records found in the NASA Aeronautics and Space Database. The scope of this topic includes technologies for the crew exploration vehicle. This area of focus is one of the enabling technologies as defined by NASA s Report of the President s Commission on Implementation of United States Space Exploration Policy, published in June 2004.
    Keywords: Spacecraft Propulsion and Power
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  • 59
    Publication Date: 2013-08-31
    Description: CuIn(1-x)Ga(x)S2 (CIGS2) thin-film solar cells are of interest for space power applications because of the near optimum bandgap for AM0 solar radiation in space. CIGS2 thin film solar cells on flexible stainless steel (SS) may be able to increase the specific power by an order of magnitude from the current level of 65 Wkg(sup -1). CIGS solar cells are superior to the conventional silicon and gallium arsenide solar cells in the space radiation environment. This paper presents research efforts for the development of CIGS2 thin-film solar cells on 127 micrometers and 20 micrometers thick, bright-annealed flexible SS foil for space power. A large-area, dual-chamber, inline thin film deposition system has been fabricated. The system is expected to provide thickness uniformity of plus or minus 2% over the central 5" width and plus or minus 3% over the central 6" width. During the next phase, facilities for processing larger cells will be acquired for selenization and sulfurization of metallic precursors and for heterojunction CdS layer deposition both on large area. Small area CIGS2 thin film solar cells are being prepared routinely. Cu-rich Cu-Ga/In layers were sputter-deposited on unheated Mo-coated SS foils from CuGa (22%) and In targets. Well-adherent, large-grain Cu-rich CIGS2 films were obtained by sulfurization in a Ar: H2S 1:0.04 mixture and argon flow rate of 650 sccm, at the maximum temperature of 475 C for 60 minutes with intermediate 30 minutes annealing step at 120 C. Samples were annealed at 500 C for 10 minutes without H2S gas flow. The intermediate 30 minutes annealing step at 120 C was changed to 135 C. p-type CIGS2 thin films were obtained by etching the Cu-rich layer segregated at the surface using dilute KCN solution. Solar cells were completed by deposition of CdS heterojunction partner layer by chemical bath deposition, transparent-conducting ZnO/ZnO: Al window bilayer by RF sputtering, and vacuum deposition of Ni/Al contact fingers through metal mask. PV parameters of a CIGS2 solar cell on 127 micrometers thick SS flexible foil measured under AM 0 conditions at NASA GRC were: V(sub oc) = 802.9 mV, J(sub sc) = 25.07 mA per square centimeters, FF = 60.06%, and efficiency 0 = 8.84%. For this cell, AM 1.5 PV parameters measured at NREL were: V(sub oc) = 788 mV, J(sub sc) = 19.78 mA per square centimeter, FF = 59.44%, efficiency 0 = 9.26%. Quantum efficiency curve showed a sharp QE cutoff equivalent to CIGS2 bandgap of approximately 1.50 eV, fairly close to the optimum value for efficient AM0 PV conversion in the space.
    Keywords: Spacecraft Propulsion and Power
    Type: 17th Space Photovoltaic Research and Technology Conference; 91-100; NASA/CP-2002-211831
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  • 60
    Publication Date: 2013-08-31
    Description: The historical background and characteristics of the experimental flights of ion propulsion systems and the major ground-based technology demonstrations are reviewed. The results of the first successful ion engine flight in 1964, Space Electric Rocket Test (SERT) I, which demonstrated ion beam neutralization, are discussed along with the extended operation of SERT II starting in 1970. These results together with the technologies employed on the early cesium engine flights, the applications technology satellite series, and the ground-test demonstrations, have provided the evolutionary path for the development of xenon ion thruster component technologies, control systems, and power circuit implementations. In the 1997-1999 period, the communication satellite flights using ion engine systems and the Deep Space 1 flight confirmed that these auxiliary and primary propulsion systems have advanced to a high level of flight readiness.
    Keywords: Spacecraft Propulsion and Power
    Type: Journal on Propulsion and Power; Volume 17; No. 3; 517-526
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  • 61
    Publication Date: 2013-08-31
    Description: A series of Reynolds-averaged Navier-Stokes calculations were employed to study the performance of rocket-based combined-cycle systems operating in an all-rocket mode. This parametric series of calculations were executed within a statistical framework, commonly known as design of experiments. The parametric design space included four geometric and two flowfield variables set at three levels each, for a total of 729 possible combinations. A D-optimal design strategy was selected. It required that only 36 separate computational fluid dynamics (CFD) solutions be performed to develop a full response surface model, which quantified the linear, bilinear, and curvilinear effects of the six experimental variables. The axisymmetric, Reynolds-averaged Navier-Stokes simulations were executed with the NPARC v3.0 code. The response used in the statistical analysis was created from Isp efficiency data integrated from the 36 CFD simulations. The influence of turbulence modeling was analyzed by using both one- and two-equation models. Careful attention was also given to quantify the influence of mesh dependence, iterative convergence, and artificial viscosity upon the resulting statistical model. Thirteen statistically significant effects were observed to have an influence on rocket-based combined-cycle nozzle performance. It was apparent that the free-expansion process, directly downstream of the rocket nozzle, can influence the Isp efficiency. Numerical schlieren images and particle traces have been used to further understand the physical phenomena behind several of the statistically significant results.
    Keywords: Spacecraft Propulsion and Power
    Type: Journal of Propulsion and Power; Volume 16; No. 6; 1030-1039
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  • 62
    Publication Date: 2011-08-23
    Description: A goal of the GTX effort has been to demonstrate the feasibility of a single stage- to- orbit (SSTO) vehicle that delivers a small payload to low earth orbit. The small payload class was chosen in order to minimize the risk and cost of development of this revolutionary system. A preliminary design study by the GTX team has resulted in the current configuration that offers considerable promise for meeting the stated goal. The size and gross lift-off weight resulting from scaling the current design to closure however may be considered impractical for the small payload. In lieu of evolving the project's reference vehicle to a large-payload class, this paper offers the alternative of using solid-rocket motors in order to close the vehicle at a practical scale. This approach offers a near-term, quasi-reusable system that easily evolves to reusable SSTO following subsequent development and optimization. This paper presents an overview of the impact of the addition of SRM's to the GTX reference vehicle's performance and trajectory. The overall methods of vehicle modeling and trajectory optimization will also be presented. A key element in the trajectory optimization is the use of the program OTIS 3.10 that provides rapid convergence and a great deal of flexibility to the user. This paper will also present the methods used to implement GTX requirements into OTIS modeling.
    Keywords: Spacecraft Propulsion and Power
    Type: 26th JANNAF Airbreathing Propulsion Subcommittee Meeting; Volume 1; 305-320; CPIA-Publ-713-Vol-1
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  • 63
    Publication Date: 2016-06-07
    Description: Joints in the Space Shuttle solid rocket motors are sealed by O-rings to contain combustion gases inside the rocket that reach pressures of up to 900 psi and temperatures of up to 5500 F. To provide protection for the O-rings, the motors are insulated with either phenolic or rubber insulation. Gaps in the joints leading up to the O-rings are filled with polysulfide joint-fill compounds as an additional level of protection. The current RSRM nozzle-to-case joint design incorporating primary, secondary, and wiper O-rings experiences gas paths through the joint-fill compound to the innermost wiper O-ring in about one out of every seven motors. Although this does not pose a safety hazard to the motor, it is an undesirable condition that NASA and rocket manufacturer Thiokol want to eliminate. Each nozzle-to-case joint gas path results in extensive reviews and evaluation before flights can be resumed. Thiokol and NASA Marshall are currently working to improve the nozzle-to-case joint design by implementing a more reliable J-leg design that has been used successfully in the field and igniter joint. They are also planning to incorporate the NASA Glenn braided carbon fiber thermal barrier into the joint. The thermal barrier would act as an additional level of protection for the O-rings and allow the elimination of the joint-fill compound from the joint.
    Keywords: Spacecraft Propulsion and Power
    Type: 1999 NASA Seal/Secondary Air System Workshop; Volume 1; 299-315; NASA/CP-2000-210472/VOL1
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  • 64
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The NASA Glenn Research Center is developing Rocket-Based Combined-Cycle (RBCC) propulsion technology for application to reusable launch vehicles in its "Trailblazer" program. This presentation will explain the cost reduction potential of RBCC propulsion, highlight the major technical issues, and describe the elements of the Trailblazer program.
    Keywords: Spacecraft Propulsion and Power
    Type: 1999 NASA Seal/Secondary Air System Workshop; Volume 1; 433-457; NASA/CP-2000-210472/VOL1
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  • 65
    Publication Date: 2016-06-07
    Description: This paper presents the status of analyses on three Rocket Based Combined Cycle (RBCC) configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics (CFD) analysis on a Penn State RBCC test rig, the proposed Draco axisymmetric RBCC engine and the Trailblazer engine. The intent of the analysis on the Penn State test rig is to benchmark the Finite Difference Navier Stokes (FDNS) code for ejector mode fluid dynamics. The Draco analysis was a trade study to determine the ejector mode performance as a function of three engine design variables. The Trailblazer analysis is to evaluate the nozzle performance in scramjet mode. Results to date of each analysis are presented.
    Keywords: Spacecraft Propulsion and Power
    Type: The Tenth Thermal and Fluids Analysis Workshop; NASA/CP-2001-211141
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  • 66
    Publication Date: 2016-06-07
    Description: Current system simulations are mature, difficult to modify, and poorly documented. Probabilistic life prediction techniques for space applications are in their early application stage. Many parts of the full system, variable fidelity simulation, have been demonstrated individually or technology is available from aeronautical applications. A 20% reduction in time to design with improvements in performance and risk reduction is anticipated. GRC software development will proceed with similar development efforts in aeronautical simulations. Where appropriate, parallel efforts will be encouraged/tracked in high risk areas until success is assured.
    Keywords: Spacecraft Propulsion and Power
    Type: ST Day 2000: Risk Reduction for The Next Generations
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  • 67
    Publication Date: 2016-06-07
    Description: It is the goal of this activity to develop 50 kW class Hall thruster technology in support of cost and time critical mission applications such as orbit insertion. NASA Marshall Space Flight Center is tasked to develop technologies that enable cost and travel time reduction of interorbital transportation. Therefore, a key challenge is development of moderate specific impulse (2000-3000 s), high thrust-to-power electric propulsion. NASA Glenn Research Center is responsible for development of a Hall propulsion system to meet these needs. First-phase, sub-scale Hall engine development completed. A 10 kW engine designed, fabricated, and tested. Performance demonstrated 〉2400 s, 〉500 mN thrust over 1000 hours of operation documented.
    Keywords: Spacecraft Propulsion and Power
    Type: ST Day 2000: Risk Reduction for The Next Generations
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  • 68
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
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  • 69
    Publication Date: 2018-06-08
    Description: Development of MEMS (Microelectromechanical Systems) micropropulsion at the Jet Propulsion Laboratory (JPL) is reviewed. This includes a vaporizing liquid micro-thruster for microspacecraft attitude control, a micro-ion emgine for microspacecraft primary propulsion or large spacecraft fine attitude control, as well as several valve studies, including a solenoid valve studied in collaboration with Moog Space Products Division, and a piezoelectric micro-valve.
    Keywords: Spacecraft Propulsion and Power
    Type: IAAA Symposium for Small Satellite for Earth Observation; Berlin; Germany
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  • 70
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: Deep Space 1 Technology Validatation Symposium; Pasadena, CA; United States
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  • 71
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: 2000 IEEE Aerospace Conference; Big Sky, MT; United States
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  • 72
    Publication Date: 2018-06-08
    Description: Formation flying and microspacecraft constellation missions pose new propulsion requirements. Formationflying spacecraft, due to the tight positioning and pointing control requirements, may need thrust control within 1- 20 uN to an accuracy of 0.1 uN for LISA and ST-7, for example. Future missions may have extended thrust ranges into the sub - mN range. However, all do require high specific impulses (〉500 sec) due to long required thruster firings.
    Keywords: Spacecraft Propulsion and Power
    Type: AIAA Nanotech 2002; Houston, TX; United States
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  • 73
    Publication Date: 2018-06-08
    Description: This paper focuses on Nuclear Electric Propulsion (NEP) as a means to transport large payloads to targets in the solar system which are energetically difficult to reach.
    Keywords: Spacecraft Propulsion and Power
    Type: Space Technology and Applications International Forum 2001 18th Symposium on nuclear power and propulsion; Albuquerque, NM; United States
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  • 74
    Publication Date: 2018-06-08
    Description: The successful demonstration of ion propulsion on NASA's Deep Space 1 mission has stimulated substantial interest in the application of this technology to future solar system exploration missions.
    Keywords: Spacecraft Propulsion and Power
    Type: 2003 Joint Propulsion Conference; Huntsville, AL; United States
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  • 75
    Publication Date: 2018-06-08
    Description: A Vaporizing Liquid Micro-Thruster (VLM) microfabricated thruster was tested on water propellant on a thrust stand and performance data obtained.
    Keywords: Spacecraft Propulsion and Power
    Type: International Electric Propulsion Conference 2003; Toulouse; France
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  • 76
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: 28th International Electric Propulsion Conference; Toulouse; France
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  • 77
    Publication Date: 2018-06-08
    Description: This paper presents a piezoelectric microvalve technology with a high pressure handling capability for micropropulsion applications.
    Keywords: Spacecraft Propulsion and Power
    Type: ASME International Mechanical Congree and Exposition; New Orleans, LA; United States
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  • 78
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    In:  Other Sources
    Publication Date: 2018-06-11
    Description: This viewgraph presentation reviews the design and development of the Disturbance Reduction System (DRS). The colloidal microthrusters will allow for precise, quiet spacecraft position and attitude control. The DRS will be attached to ESAS's SMART-2 spacecraft.
    Keywords: Spacecraft Propulsion and Power
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  • 79
    Publication Date: 2018-06-08
    Description: This paper provides an overview of the system and presents the first flight validation data on an ion propulsion system in interplanetary space.
    Keywords: Spacecraft Propulsion and Power
    Type: IEEE Aerospace Conference; Big Sky, MT; United States
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  • 80
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: DS1 Technology Validation Symposium; Pasadena, CA; United States
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  • 81
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: 2nd International Workshop on Liquid Rocket Propulsion; Heilbronn; Germany
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  • 82
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: Informational Electric Propulsion Conference; Toulouse; France
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  • 83
    Publication Date: 2018-06-12
    Description: The advantages, development, and fabrication of toroidal propellant tanks are profiled in this viewgraph presentation. Several images are included of independent research and development (IR&D) of toroidal propellant tanks at Marshall Space Flight Center (MSFC). Other images in the presentation give a brief overview of Thiokol conformal tank technology development. The presentation describes Thiokol's approach to continuous composite toroidal tank fabrication in detail. Images are shown of continuous and segmented toroidal tanks fabricated by Thiokol.
    Keywords: Spacecraft Propulsion and Power
    Type: 5th Conference on Aerospace Materials, Processes, and Environmental Technology; NASA/CP-2003-212931
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  • 84
    Publication Date: 2018-06-12
    Description: The ion thruster is one of the most promising solar electric propulsion (SEP) technologies to support future Outer Planet missions (place provided link below here) for NASA's Office of Space Science. Typically, ion thrusters are used in high Isp- low thrust applications that require long lifetimes, as well as, higher efficiency over state-of-the-art chemical propulsion systems.Today, the standard for ion thrusters is the SEP Technology Application Readiness (NSTAR) thruster. Jet Propulsion Laboratory's (JPL's) extended life test (ELT) of the DS 1 flight spare NSTAR thruster began in October 1998. This test successfully demonstrated lifetime of the NSTAR flight spare thruster, which will provide a solid basis for selection of ion thrusters for future Code S missions. The NSTAR ELT was concluded on June 30,2003 after 30,352 hours. The purpose of the Next Generation Ion (NGI) activities is to advance Ion propulsion system technologies through the development of NASA's Evolutionary Xenon Thruster (NEXT). The goal of NEXT is to more than double the power capability and lifetime throughput (the total amount of propellant which can be processed) while increasing the Isp by 30% and the thrust by 120%.
    Keywords: Spacecraft Propulsion and Power
    Type: TECH ISP: Next Generation Ion
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  • 85
    Publication Date: 2018-06-12
    Description: Solar sailing is a unique form of propulsion where a spacecraft gains momentum from incident photons. Solar sails are not limited by reaction mass and provide continual acceleration, reduced only by the lifetime of the lightweight film in the space environment and the distance to the Sun. Once thought to be difficult or impossible, solar sailing has come out of science fiction and into the realm of possibility. Any spacecraft using this propulsion method would need to deploy a thin sail that could be as large as many kilometers in extent. The availability of strong, ultra lightweight, and radiation resistant materials will determine the future of solar sailing. The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) is concentrating research into the utilization of ultra lightweight materials for spacecraft propulsion. The Space Environmental Effects Team at MSFC is actively characterizing candidate solar sail material to evaluate the thermo-optical and mechanical properties after exposure to space environmental effects. This paper will describe the irradiation of candidate solar sail materials to energetic electrons, in vacuum, to determine the hardness of several candidate sail materials.
    Keywords: Spacecraft Propulsion and Power
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  • 86
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2018-06-11
    Description: This paper presents a piezoelectric microvalve technology with a high pressure handling capability for micropropulsion applications.
    Keywords: Spacecraft Propulsion and Power
    Type: Nanotech 2002 At the Edge of Revolution; Houston, TX; United States
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  • 87
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2018-06-11
    Keywords: Spacecraft Propulsion and Power
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  • 88
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2018-06-11
    Keywords: Spacecraft Propulsion and Power
    Type: 2004 Joint Propulsion Conference; FL; United States
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  • 89
    Publication Date: 2018-06-12
    Description: The objective of this study is to conduct a unified computational analysis for computing design parameters such as axial thrust, convective and radiative wall heat fluxes for regeneratively cooled liquid rocket engine nozzles, so as to develop a computational strategy for computing those parameters through parametric investigations. The computational methodology is based on a multidimensional, finite-volume, turbulent, chemically reacting, radiating, unstructured-grid, and pressure-based formulation, with grid refinement capabilities. Systematic parametric studies on effects of wall boundary conditions, combustion chemistry, radiation coupling, computational cell shape, and grid refinement were performed and assessed. Under the computational framework of this study, it is found that the computed axial thrust performance, flow features, and wall heat fluxes compared well with those of available data and calculations, using a strategy of structured-grid dominated mesh, finite-rate chemistry, and cooled wall boundary condition.
    Keywords: Spacecraft Propulsion and Power
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  • 90
    Publication Date: 2018-06-12
    Description: The focus of the evaluation was to develop a back-up method to cell plating for the improvement or repair of seal surface defects within D6-AC steel and 7075-T73 aluminum used in the RSRM program. Several techniques were investigated including thermal and non-thermal based techniques. Ideally the repair would maintain the inherent properties of the substrate without losing integrity at the repair site. The repaired sites were tested for adhesion, corrosion, hardness, microhardness, surface toughness, thermal stability, ability to withstand bending of the repair site, and the ability to endure a high-pressure water blast without compromising the repaired site. The repaired material could not change the inherent properties of the substrate throughout each of the test in order to remain a possible technique to repair the RSRM substrate materials. One repair method, Electro-Spark Alloying, passed all the testing and is considered a candidate for further evaluation.
    Keywords: Spacecraft Propulsion and Power
    Type: 5th Conference on Aerospace Materials, Processes, and Environmental Technology; NASA/CP-2003-212931
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  • 91
    Publication Date: 2018-06-06
    Description: Traditional methods of actuating spacecraft in sparse aperture arrays use propellant as a reaction mass. For formation flying systems, propellant becomes a critical consumable which can be quickly exhausted while maintaining relative orientation. Additional problems posed by propellant include optical contamination, plume impingement, thermal emission, and vibration excitation. For these missions where control of relative degrees of freedom is important, we consider using a system of electromagnets, in concert with reaction wheels, to replace the consumables. Electromagnetic Formation Flight sparse apertures, powered by solar energy, are designed differently from traditional propulsion systems, which are based on V. This paper investigates the design of sparse apertures both inside and outside the Earth's gravity field.
    Keywords: Spacecraft Propulsion and Power
    Type: Proceedings from the 2nd International Symposium on Formation Flying Missions and Technologies; NASA/CP-2005-212781
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  • 92
    Publication Date: 2018-06-06
    Description: The Wilkinson Microwave Anisotropy Probe is a follow-on to the Differential Microwave Radiometer instrument on the Cosmic Background Explorer. Attitude control system engineers discovered sixteen months before launch that configuration changes after the critical design review had resulted in a significant migration of the spacecraft's center of mass. As a result, the spacecraft no longer had a viable backup control mode in the event of a failure of the negative pitch-axis thruster. A tiger team was formed and identified potential solutions to this problem, such as adding thruster-plume shields to redirect thruster torque, adding or removing mass from the spacecraft, adding an additional thruster, moving thrusters, bending thruster nozzles or propellant tubing, or accepting the loss of redundancy. The project considered the impacts on mass, cost, fuel budget, and schedule for each solution, and decided to bend the propellant tubing of the two roll-control thrusters to allow the pair to be used for backup control in the negative pitch axis. This paper discusses the problem and the potential solutions, and documents the hardware and software changes and verification performed. Flight data are presented to show the on-orbit performance of the propulsion system and lessons learned are described.
    Keywords: Spacecraft Propulsion and Power
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  • 93
    Publication Date: 2018-06-05
    Description: The Radiation and Technology Demonstration (RTD) Mission is under joint study by three NASA Centers: the NASA Johnson Space Center, the NASA Goddard Space Flight Center, and the NASA Glenn Research Center at Lewis Field. This Earth-orbiting mission, which may launch on a space shuttle in the first half of the next decade, has the primary objective of demonstrating high-power electric thruster technologies. Secondary objectives include better characterization of Earth's Van Allen trapped-radiation belts, measurement of the effectiveness of the radiation shielding for human protection, measurement of radiation effects on advanced solar cells, and demonstration of radiation-tolerant microelectronics. During the mission, which may continue up to 1 year, the 2000-kg RTD spacecraft will first spiral outward from the shuttle-deployed, medium-inclination, low Earth orbit. By the phased operation of a 10-kW Hall thruster and a 10-kW Variable Specific Impulse Magneto-Plasma Rocket, the RTD spacecraft will reach a low-inclination Earth orbit with a radius greater than five Earth radii. This will be followed by an inward spiraling orbit phase when the spacecraft deploys 8 to 12 microsatellites to map the Van Allen belts. The mission will conclude in low Earth orbit with the possible retrieval of the spacecraft by the space shuttle. A conceptual RTD spacecraft design showing two photovoltaic (PV) array wings, the Hall thruster with propellant tanks, and stowed microsatellites is presented. Early power system studies assessed five different PV array design options coupled with a 120-Vdc power management and distribution system (PMAD) and secondary lithium battery energy storage. Array options include (1) state-of-the-art 10-percent efficient three-junction amorphous SiGe thin-film cells on thin polymer panels deployed with an inflatable (or articulated) truss, (2) SCARLET array panels, (3) commercial state-of-the-art, planar PV array rigid panels with 25-percent efficient, three-junction GaInP2/GaAs/Ge solar cells, (4) rigid panels with 25-percent efficient, three-junction GaInP2/GaAs/Ge solar cells, in a 2 -concentrator trough configuration, and (5) thin polymer panels with 25-percent efficient, three-junction GaInP2/GaAs/Ge solar cells deployed with an inflatable (or articulated) truss. To assess the relative merits of these PV array design options, the study group developed a dedicated Fortran code to predict power system performance and estimate system mass. This code also modeled Earth orbital environments important for accurately predicting PV array performance. The most important environmental effect, solar cell radiation degradation, was calculated from electron-proton fluence input from the industry standard AE8/AP8 trapped radiation models and the concept of damage equivalence. Power systems were sized to provide 10 kW of thruster power and approximately 1 kW of spacecraft power at end of life. Of the five PV array design options, the option 1 (thin-film cells) power system was the most massive 590 kg, whereas the option 4 (trough concentrator) power system was the lightest 260 kg. Arguably, the lowest cost would come from the option 3 (commercial array panels) power system with an acceptable, albeit greater, system mass of 320 kg. Predicted power system performance during the spiral-out mission phase is shown the preceding graph for the option 5 (flexible-panel) array. From the results, the radiation-induced power loss over time is evident as the spacecraft slowly spirals outward through the trapped proton belt. The importance of the spiral trip time is also evident in the two curves representing 74-day and 182-day spiral-out periods. The longer spiral time introduces a beginning-of-life power oversizing penalty greater than 1 kW. Future studies will analyze power system performance and mass with a 50-Vdc power management and distribution architecture favorable to the VASIMR thruster and longer missions.
    Keywords: Spacecraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 94
    Publication Date: 2018-06-05
    Description: The Department of Energy (DOE), Germantown, Maryland, Stirling Technology Company (STC), Kennewick, Washington, and NASA Glenn Research Center are developing a free-piston Stirling convertor for a high-efficiency Stirling Radioisotope Generator for NASA Space Science missions. This generator is being developed for multimission use, including providing electric power for unmanned Mars rovers and for deep space missions. STC is developing the 55-W Technology Demonstration Convertor (TDC) under contract to DOE. Glenn is conducting an in-house technology project to assist in developing the convertor for readiness for space qualification and mission implementation. As part of this effort, a Stirling Research Laboratory was established to test the TDC's and related technologies. A key task is providing an independent verification and validation of the TDC performance. Four TDC's are now being tested at Glenn. Acceptance testing has been completed for all convertors, and in general, performance agreed well with that achieved by STC prior to the delivery of the convertors. Performance mapping has also been completed on two of the convertors over a range of hot-end temperatures (450 to 650 C), cold-end temperatures (80 to 120 C), and piston amplitudes (5.2 to 6.2 mm). These test data are available online at http://www.grc.nasa.gov/WWW/tmsb/. The TDC's can be tested in either a horizontal orientation with dual-opposed convertors or in a vertical orientation with a single convertor. Synchronized dual-opposed pairs are used for dynamically balanced operation that results in very low levels of vibration. The Stirling Research Laboratory also supports launch environment testing of the TDC's in Glenn's Structural Dynamics Laboratory and electromagnetic interference and electromagnetic compatibility characterization and reduction efforts. In addition, the TDC's will be used for long-term endurance testing, and preparations are underway for unattended operation.
    Keywords: Spacecraft Propulsion and Power
    Type: Research and Technology 2001; NASA/Tm-2002-211333
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  • 95
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-05
    Description: Pulse Detonation Engine Technology is currently being investigated at Glenn for both airbreathing and rocket propulsion applications. The potential for both mechanical simplicity and high efficiency due to the inherent near-constant-volume combustion process, may make Pulse Detonation Engines (PDE's) well suited for a number of mission profiles. Assessment of PDE cycles requires a simulation capability that is both fast and accurate. It should capture the essential physics of the system, yet run at speeds that allow parametric analysis. A quasi-one-dimensional, computational-fluid-dynamics-based simulation has been developed that may meet these requirements. The Euler equations of mass, momentum, and energy have been used along with a single reactive species transport equation, and submodels to account for dominant loss mechanisms (e.g., viscous losses, heat transfer, and valving) to successfully simulate PDE cycles. A high-resolution numerical integration scheme was chosen to capture the discontinuities associated with detonation, and robust boundary condition procedures were incorporated to accommodate flow reversals that may arise during a given cycle. The accompanying graphs compare experimentally measured and computed performance over a range of operating conditions for a particular PDE. Experimental data were supplied by Fred Schauer and Jeff Stutrud from the Air Force Research Laboratory at Wright-Patterson AFB and by Royce Bradley from Innovative Scientific Solutions, Inc. The left graph shows thrust and specific impulse, Isp, as functions of equivalence ratio for a PDE cycle in which the tube is completely filled with a detonable hydrogen/air mixture. The right graph shows thrust and specific impulse as functions of the fraction of the tube that is filled with a stoichiometric mixture of hydrogen and air. For both figures, the operating frequency was 16 Hz. The agreement between measured and computed values is quite good, both in terms of trend and magnitude. The error is under 10 percent everywhere except for the thrust value at an equivalence ratio of 0.8 in the left figure, where it is 14 percent. The simulation results shown were made using 200 numerical cells. Each cycle of the engine, approximately 0.06 sec, required 2.0 min of CPU time on a Sun Ultra2. The simulation is currently being used to analyze existing experiments, design new experiments, and predict performance in propulsion concepts where the PDE is a component (e.g., hybrid engines and combined cycles).
    Keywords: Spacecraft Propulsion and Power
    Type: Research and Technology 2000; NASA/TM-2001-210605
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  • 96
    Publication Date: 2018-06-12
    Description: Making measurements of electron emission properties of insulators is difficult since insulators can charge either negatively or positively under charge particle bombardment. In addition, high incident energies or high fluences can result in modification of a material s conductivity, bulk and surface charge profile, structural makeup through bond breaking and defect creation, and emission properties. We discuss here some of the charging difficulties associated with making insulator-yield measurements and review the methods used in previous studies of electron emission from insulators. We present work undertaken by our group to make consistent and accurate measurements of the electron/ion yield properties for numerous thin-film and thick insulator materials using innovative instrumentation and techniques. We also summarize some of the necessary instrumentation developed for this purpose including fast response, low-noise, high-sensitivity ammeters; signal isolation and interface to standard computer data acquisition apparatus using opto-isolation, sample-and-hold, and boxcar integration techniques; computer control, automation and timing using Labview software; a multiple sample carousel; a pulsed, compact, low-energy, charge neutralization electron flood gun; and pulsed visible and UV light neutralization sources. This work is supported through funding from the NASA Space Environments and Effects Program and the NASA Graduate Research Fellowship Program.
    Keywords: Spacecraft Propulsion and Power
    Type: 8th Spacecraft Charging Technology Conference; NASA/CP-2004-213091
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  • 97
    Publication Date: 2018-06-06
    Description: Theory and experiments involving single droplet combustion date back to 1953, with the first microgravity work appearing in 1956. The problem of a spherical droplet burning in an infinite, quiescent microgravity environment is a classical problem in combustion research with the classical solution appearing in nearly every textbook on combustion. The microgravity environment offered by ground-based facilities such as drop towers and space-based facilities is ideal for studying the problem experimentally. A recent review by Choi and Dryer shows significant advances in droplet combustion have been made by studying the problem experimentally in microgravity and comparing the results to one dimensional theoretical and numerical treatments of the problem. Studying small numbers of interacting droplets in a well-controlled geometry represents a logical step in extending single droplet investigations to more practical spray configurations. Studies of droplet interactions date back to Rex and co-workers, and were recently summarized by Annamalai and Ryan. All previous studies determined the change in the burning rate constant, k, or the flame characteristics as a result of interactions. There exists almost no information on how droplet interactions a effect extinction limits, and if the extinction limits change if the array is in the diffusive or the radiative extinction regime. Thus, this study examined experimentally the effect that droplet interactions have on the extinction process by investigating the simplest array configuration, a binary droplet array. The studies were both in normal gravity, reduced pressure ambients and microgravity facilities. The microgravity facilities were the 2.2 and 5.2 second drop towers at the NASA Glenn Research Center and the 10 second drop tower at the Japan Microgravity Center. The experimental apparatus and the data analysis techniques are discussed in detail elsewhere.
    Keywords: Spacecraft Propulsion and Power
    Type: Seventh International Workshop on Microgravity Combustion and Chemically Reacting Systems; 1-4; NASA/CP-2003-212376-REV1
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  • 98
    Publication Date: 2018-06-06
    Description: In recent years, there has been a tendency toward shrinking the size of spacecraft. New classes of spacecraft called micro-spacecraft have been defined by their mass, power, and size ranges. Spacecraft in the range of 20 to 100 kg represent the class most likely to be utilized by most small sat users in the near future. There are also efforts to develop 10 to 20 kg class spacecraft for use in satellite constellations. More ambitious efforts will be to develop spacecraft less than 10 kg, in which MEMS fabrication technology is required. These new micro-spacecraft will require new micro-propulsion technology. Although micro-propulsion includes electric propulsion approaches, the focus of this proposed program is micro-chemical propulsion which requires the development of microcombustors. As combustors are scaled down, the surface to volume ratio increases. The heat release rate in the combustor scales with volume, while heat loss rate scales with surface area. Consequently, heat loss eventually dominates over heat release when the combustor size becomes smaller, thereby leading to flame quenching. The limitations imposed on chamber length and diameter has an immediate impact on the degree of miniaturization of a micro-combustor. Before micro-combustors can be realized, such a difficulty must be overcome. One viable combustion alternative is to take advantage of surface catalysis. Micro-chemical propulsion for small spacecraft can be used for primary thrust, orbit insertion, trajectory-control, and attitude control. Grouping micro-propulsion devices in arrays will allow their use for larger thrust applications. By using an array composed of hundreds or thousands of micro-thruster units, a particular configuration can be arranged to be best suited for a specific application. Moreover, different thruster sizes would provide for a range of thrust levels (from N s to mN s) within the same array. Several thrusters could be fired simultaneously for thrust levels higher than the basic units, or in a rapid sequence in order to provide gradual but steady low-g acceleration. These arrays of micro-propulsion systems would offer unprecedented flexibility and redundancy for satellite propulsion and reaction control for launch vehicles. A high-pressure bi-propellant micro-rocket engine is already being developed using MEMS technology. High pressure turbopumps and valves are to be incorporated onto the rocket chip . High pressure combustion of methane and O2 in a micro-combustor has been demonstrated without catalysis, but ignition was established with a spark. This combustor has rectangular dimensions of 1.5 mm by 8 mm (hydraulic diameter 3.9 mm) and a length of 4.5 mm and was operated at 1250 kPa with plans to operate it at 12.7 MPa. These high operating pressures enable the combustion process in these devices, but these pressures are not practical for pressure fed satellite propulsion systems. Note that the use of these propellants requires an ignition system and that the use of a spark would impose a size limitation to this micro-propulsion device because the spark unit cannot be shrunk proportionately with the thruster. Results presented in this paper consist of an experimental evaluation of the minimum catalyst temperature for initiating/supporting combustion in sub-millimeter diameter tubes. The tubes are resistively heated and reactive premixed gases are passed through the tubes. Tube temperature and inlet pressure are monitored for an indication of exothermic reactions and composition changes in the gases.
    Keywords: Spacecraft Propulsion and Power
    Type: Seventh International Workshop on Microgravity Combustion and Chemically Reacting Systems; 385-388; NASA/CP-2003-212376/REV1
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  • 99
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-06
    Description: The fellowship work this summer will be in support of the development of a fuel mixer for a liquid fuel reformer that is upstream of a fuel cell. Tasks for the summer shall consist of design of a fuel mixer, setup of the laser diagnostics for determining the degree of fuel mixing, and testing of the fuel mixer. The fuel mixer shall be a venturi section with fuel injected at or near the throat, and an air swirler upstream of the venturi. Data to determine the performance of the mixer shall be taken using a Phase Doppler Particle Analyzer (PDPA).
    Keywords: Spacecraft Propulsion and Power
    Type: NASA-OAI Collaborative Aerospace Research and Fellowship Program; 12-15
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  • 100
    Publication Date: 2018-06-05
    Description: Space shuttle solid rocket motor case assembly joints are sealed with conventional O-ring seals that are shielded from 5500 F combustion gases by thick layers of insulation and by special joint-fill compounds that fill assembly splitlines in the insulation. On a number of occasions, NASA has observed hot gas penetration through defects in the joint-fill compound of several of the rocket nozzle assembly joints. In the current nozzle-to-case joint, NASA has observed penetration of hot combustion gases through the joint-fill compound to the inboard wiper O-ring in one out of seven motors. Although this condition does not threaten motor safety, evidence of hot gas penetration to the wiper O-ring results in extensive reviews before resuming flight. The solid rocket motor manufacturer (Thiokol) approached the NASA Glenn Research Center at Lewis Field about the possibility of applying Glenn's braided fiber preform seal as a thermal barrier to protect the O-ring seals. Glenn and Thiokol are working to improve the nozzle-to-case joint design by implementing a more reliable J-leg design and by using a braided carbon fiber thermal barrier that would resist any hot gases that the J-leg does not block.
    Keywords: Spacecraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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