18 research outputs found

    MarcoPolo-R: Near-Earth Asteroid sample return mission selected for the assessment study phase of the ESA program cosmic vision

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    This paper presents the sample return mission to a primitive Near-Earth Asteroid (NEA) MarcoPolo-R proposed to the European Space Agency in December 2010. MarcoPolo-R was selected in February 2011 with three other missions addressing different science objectives for the two-year Assessment Phase of the Medium-Class mission competition of the Cosmic Vision 2 program for launch in 2022. The baseline target of MarcoPolo-R is the binary NEA (175706) 1996 FG3, which offers an efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of a binary target allows several scientific investigations to occur more easily than through a single object, in particular regarding the fascinating geology and geophysics of asteroids. MarcoPolo-R will rendezvous with a primitive, organic-rich NEA, scientifically characterize it at multiple scales, and return a bulk sample to Earth for laboratory analyses. The MarcoPolo-R sample will provide a representative sample from the surface of a known asteroid with known geologic context, and will contribute to the inventory of primitive material that is probably missing from the meteorite collection. The MarcoPolo-R samples will thus contribute to the exploration of the origin of planetary materials and initial stages of habitable planet formation, to the identification and characterization of the organics and volatiles in a primitive asteroid and to the understanding of the unique geomorphology, dynamics and evolution of a binary asteroid that belongs to the Potentially Hazardous Asteroid (PHA) population

    Design and construction of the MicroBooNE detector

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    This paper describes the design and construction of the MicroBooNE liquid argon time projection chamber and associated systems. MicroBooNE is the first phase of the Short Baseline Neutrino program, located at Fermilab, and will utilize the capabilities of liquid argon detectors to examine a rich assortment of physics topics. In this document details of design specifications, assembly procedures, and acceptance tests are reported

    Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond

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    Selecting fines recycle methods to optimize fluid bed combustor performance

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    Testing and analysis of a number of different fines recycle methods for fluid bed combustors has led to a generalized modeling technique. This model accounts for the effect of pertinent variables in determining overall combustion efficiencies. Computer application of this model has allowed trade-off studies to be performed that show the overall process effects of changes in individual operating parameters. Verification of the model has been accomplished in processing campaigns while combusting fuels such as graphite and bituminous coal. A 0.4 MW test unit was used for the graphite experimental work. Solid fuel was typically crushed to 5 mm maximum screen size. Bed temperatures were normally controlled at 900/sup 0/C; the combustor was an atmospheric unit with maximum in-bed pressures of 0.2 atm. Expanded bed depths ranged from 1.5 to 3 meters. Additional data was taken from recycle tests sponsored by EPRI on the B and W 6 ft x 6 ft fluid bed combustor. These tests used high sulfur coal in a 1.2 meter deep, 850/sup 0/C atmospheric fluidized bed of limestone, with low recycle rates and temperatures. Close agreement between the model and test data has been noted, with combustion efficiency predictions matching experimental results within 1%

    Putting Standards Into Practice: Evaluating the Utility of the NAGC Pre-K—Grade 12 Gifted Program Standards

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    Despite their importance, there has been surprisingly little scholarly examination of the NAGC Pre-K --Grade 12 Gifted Program Standards (NAGC, 2008/2000; Landrum, Callahan, & Shaklee, 2001) since their publication a decade ago. As part of a larger study investigating the effectiveness of local policies developed within the framework of state law, we used a qualitative approach to examine the ‘minimum’ and ‘exemplary’ criteria from the Student Identification portion of these NAGC Standards. Through this process we developed a 27-item checklist, which we then used to evaluate 43 locally developed plans for identifying diverse gifted learners from one large state in the southeastern United States. Based on this experience, we identify the strengths and weaknesses that we encountered in using the Standards for this purpose. We provide the checklist items we developed, and we offer specific suggestions for how the Gifted Program Standards in their currently ongoing revision process might be made more user-friendly for practitioners to apply toward effective evaluation of gifted program documents
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