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  • Lunar and Planetary Science and Exploration  (6)
  • NUCLEAR ENGINEERING  (2)
  • 1
    Publication Date: 2011-08-16
    Description: A critical experiment with spherical symmetry has been conducted on the gas core nuclear reactor concept. The nonspherical perturbations in the experiment were evaluated experimentally and produce corrections to the observed eigenvalue of approximately 1% delta k. The reactor consisted of a low density, central uranium hexafluoride gaseous core, surrounded by an annulus of void or low density hydrocarbon, which in turn was surrounded with a 97-cm-thick heavy water reflector.
    Keywords: NUCLEAR ENGINEERING
    Type: Nuclear Science and Engineering; 47; Jan. 197
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  • 2
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    In:  Other Sources
    Publication Date: 2018-06-08
    Keywords: Lunar and Planetary Science and Exploration
    Type: Looking at EAP Intervention Techniques; Vancouver, British Columbia; Canada
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  • 3
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    Publication Date: 2018-06-08
    Keywords: Lunar and Planetary Science and Exploration
    Type: Looking at EAP Intervention Techniques; Vancouver, British Columbia; Canada
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  • 4
    Publication Date: 2019-06-27
    Description: Variations in cavity wall and injection configurations of the gas core reactor were aimed at establishing flow patterns that give a maximum of the nuclear criticality eigenvalue. Correlation with the nuclear effect was made using multigroup diffusion theory normalized by previous benchmark critical experiments. Air was used to simulate the hydrogen propellant in the flow tests, and smoked air, argon, or Freon to simulate the central nuclear fuel gas. Tests were run both in the down-firing and upfiring directions. Results showed that acceptable flow patterns with volume fraction for the simulated nuclear fuel gas and high flow rate ratios of propellant to fuel can be obtained. Using a point injector for the fuel, good flow patterns are obtained by directing the outer gas at high velocity long the cavity wall, using louvered injection schemes. Recirculation patterns were needed to stabilize the heavy central gas when different gases are used.
    Keywords: NUCLEAR ENGINEERING
    Type: NASA-CR-121191 , ANCR-1118
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  • 5
    Publication Date: 2019-07-20
    Description: The Mars Science Laboratory (MSL) Curiosity rover has spent the last two years investigating a prominent resistant ridge, informally named the Vera Rubin Ridge (VRR), at the base of Mount Sharp (Aeolis Mons). The ridge has been a high priority science target for the MSL mission since landing in Gale crater more than 6 years ago because of the detection of a strong hematite spectral signature, and its distinct topography. Examining the chemistry of the ridge can aid in determining the relationship to other rocks analyzed during the rover traverse, specifically the Murray formation (fm) encountered below the ridge. We can also determine compositional trends with elevation and/or laterally within the ridge, and whether spectral properties observed on the ridge, both from orbit and in situ, correspond with changes in chemistry. The composition of the ridge, combined with mineralogy of drilled samples, can help to elucidate bigger picture questions regarding depositional environment, possible changing lake water chemistry and diagenetic/alteration history.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN66081 , Lunar and Planetary Science Conference (LPSC); Mar 18, 2019 - Mar 22, 2019; Woodlands, TX; United States
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  • 6
    Publication Date: 2019-07-30
    Description: Characterizing the history of aqueous activity at the martian surface has been an objective of the Mars Exploration Rovers (MER) and the Mars Science Laboratory (MSL). Although the geologic context of the three landing sites are different, comparisons across the datasets can provide greater insight than using data from one mission alone. The Alpha Particle X-ray Spectrometer (APXS) is common to all three rovers (Spirit at Gusev crater, Opportunity at Meridiani Planum, and Curiosity at Gale crater) and provides a consistent basis for these comparisons. Soil and Dust: Fine grained basaltic soils and dust are remarkably uniform in chemical composition across multiple landing sites. These similarities in the concentrations of major, minor, and a few trace elements (Fig. 1) are indicative of planet-wide consistency in the composition of source materials for the soils. S and Cl vary by a factor of two in the soil and dust, but there is no clear association with any bulk cation (e.g., no correlation between S and total Ca, Mg, or Fe in soils). These volatile elements, however, are clearly associated with the nanophase-ferric iron component in the soil established by Mssbauer spectroscopy [1,2]. S and Cl likely originated as acidic species from volcanic out-gassing and subsequently coalesced on dust and sand grain surfaces, possibly with an affinity towards Fe3+ sites. Importantly, given the mobility of S and Cl in aqueous exposures, soil samples maintaining the typical molar S/Cl ratio of ~3.7:1 indicate minimal interactions with liquid water after the addition of S and Cl. In contrast to this well-established baseline, soil samples have been discovered at all three landing sites with atypical S/Cl ratios (e.g., subsurface soils), indicative of a more complex aqueous history.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN70395 , International Conference on Mars; Jul 22, 2019 - Jul 25, 2019; Pasadena, CA; United States
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  • 7
    Publication Date: 2019-08-06
    Description: The S contents of rocks and soils are indicative of various alteration processes on Mars, e.g.[1]. It has been quantified along traverses at 4 landing sites Pathfinder, both MERs and MSL by the APXS [2,3]. At the MSL and MER sites, sulfur abundances, correlations with likely bound cations and other elements, and complementary mineralogical and textural data have provided important insights into alteration processes and periods of more habitable environments in the distant past.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN70393 , International Conference on Mars; Jul 22, 2019 - Jul 25, 2019; Pasadena, CA; United States
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  • 8
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    Publication Date: 2019-07-10
    Description: Evidence for dissected duricrust was identified in high resolution MOC images. Analysis of all available images was used to map the global distribution of this terrain. It is apparently restricted to two latitude bands: 30-60 deg. N and 30-60 deg. S.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Lunar and Planetary Science XXXI; LPI-Contrib-1000
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