No abstract

No abstract

[1] We studied visible to near-infrared (VNIR, 0.35-2.5 mm) and middle infrared (MIR, 1800-250 cm À1 , also called thermal infrared and vibrational) spectra of basaltic tephras from Mauna Kea volcano that were altered under ambient, hydrothermal (hydrolytic and acid sulfate), and dry heat conditions. Although models of MIR spectra of altered tephras generally produce fits whose quality is reduced compared to deconvolutions of primary lithologies, they successfully identify major alteration phases (cristobalite, oxide, phyllosilicate, and sulfate) except in palagonites. MIR spectra of the <45 mm fraction of all altered tephra samples exhibit an H 2 O peak at $1640 cm À1 , but it cannot be used as an indicator of H 2 O content. This feature is present with band strengths >1% in spectra of the 500-1000 mm fraction only if phyllosilicates are present. Although Mauna Kea palagonitic tephra is considered a VNIR analog to Martian dust, comparison of MIR altered tephra spectra (<45 mm fraction) to dust spectra retrieved from Mars Global Surveyor and Mars Exploration Rover instruments do not provide good spectral matches. The best MIR match is a tephra that has a strong plagioclase feldspar transparency feature and was altered under dry, high-temperature, oxidizing conditions. This sample is not a VNIR analog and is not a process analog, but it emphasizes the mineralogical importance of plagioclase feldspar in Martian dust. No single tephra is a good spectral analog across the VNIR and MIR. We found no evidence for substantial sulfates or phyllosilicates in Mini-Thermal Emission Spectrometer (Mini-TES) spectra from Gusev Crater.Citation: Hamilton, V. E., R. V. Morris, J. E. Gruener, and S. A. Mertzman (2008), Visible, near-infrared, and middle infrared spectroscopy of altered basaltic tephras: Spectral signatures of phyllosilicates, sulfates, and other aqueous alteration products with application to the mineralogy of the Columbia Hills of Gusev Crater, Mars,

This article is a U.S. government work, and is not subject to copyright in the United States. CrossMark a r t i c l e i n f o b s t r a c tDesert Research and Technology Studies (Desert RATS) is a multi-year series of hardware and operations tests carried out annually in the high desert of Arizona on the San Francisco Volcanic Field. These activities are designed to exercise planetary surface hardware and operations in conditions where long-distance, multi-day roving is achievable, and they allow NASA to evaluate different mission concepts and approaches in an environment less costly and more forgiving than space. The results from the RATS tests allow selection of potential operational approaches to planetary surface exploration prior to making commitments to specific flight and mission hardware development. In previous RATS operations, the Science Support Room has operated largely in an advisory role, an approach that was driven by the need to provide a loose science mission framework that would underpin the engineering tests. However, the extensive nature of the traverse operations for 2010 expanded the role of the science operations and tested specific operational approaches. Science mission operations approaches from the Apollo and Mars-Phoenix missions were merged to become the baseline for this test. Six days of traverse operations were conducted during each week of the 2-week test, with three traverse days each week conducted with voice and data communications continuously available, and three traverse days conducted with only two 1-hour communications periods per day. Within this framework, the team evaluated integrated science operations management using real-time, tactical science operations to oversee daily crew activities, and strategic level evaluations of science data and daily traverse results during a post-traverse planning shift. During continuous communications, both tactical and strategic teams were employed. On days when communications were reduced to only two communications periods per day, only a strategic team was employed. The Science Operations Team found that, if communications are good and down-linking of science data is ensured, high quality science returns is possible regardless of communications. What is absent from reduced communications is the scientific interaction between the crew on the planet and the scientists on the ground. These scientific interactions were a critical part of the science process and significantly improved mission science return over reduced communications conditions. The test also showed that the quality of science return is not measurable by simple numerical quantities but is, in fact, based on strongly non-quantifiable factors, such as the interactions between the crew and the Science Operations Teams. Although the metric evaluation data suggested some trends, there was not sufficient granularity in the data or specificity in the metrics to allow those trends to be understood on numerical data alone.Published by Elsevier Ltd. on behalf of IAA.

No abstract

containment and liquid and gas phase separation in microgravity by using microporous membranes to control Hydroponic culture has traditionally been used for controlled enviwater delivery to plants. In the present configuration ronment life support systems (CELSS) because the optimal environment for roots supports high growth rates. Recent developments in of this method, nutrient solution flows under a slight zeoponic substrate and microporous tube irrigation (ZPT) also offer negative pressure through microporous tubes and is dehigh control of the root environment. This study compared the effect livered by capillary action directly to roots (Dreschel of differences in water and nutrient status of ZPT or hydroponic and Sager, 1989) or to solid substrate (Morrow et al., culture on growth and yield of wheat (Triticum aestivum L. cv. USU-1994; Tibbitts et al., 1995). A nearly constant matric Apogee). In a side-by-side test in a controlled environment, wheat potential can be maintained in solid substrate by conwas grown in ZPT and recirculating hydroponics to maturity. Water trolling water flow and pressure through microporous use by plants grown in both culture systems peaked at 15 to 20 L m Ϫ2 tubes. The dynamics of water transport through a microd Ϫ1 up to Day 40, after which it declined more rapidly for plants grown porous tube-solid substrate-plant system was studied in ZPT culture due to earlier senescence of leaves. No consistent by Steinberg and Henninger (1997), who showed that differences in water status were noted between plants grown in the two culture systems. Although yield was similar, harvest index was water holding and transport characteristics of solid sub-28% lower for plants grown in ZPT than in hydroponic culture. Sterile strate determine the range of viable operating pressures green tillers made up 12 and 0% of the biomass of plants grown in of the system. ZPT and hydroponic culture, respectively. Differences in biomass Little is known about the growth and yield of plants partitioning were attributed primarily to NH 4 -N nutrition of plants grown in solid substrate maintained at a nearly constant grown in ZPT compared with NO 3 -N in hydroponic nutrient solution.matric potential by microporous tube irrigation as com-It is probable that NH 4 -N-induced Ca deficiency produced excess pared to hydroponic culture. Cao and Tibbitts (1996) tillering and lower harvest index for plants grown in ZPT culture. compared biomass production and gas exchange of po-These results suggest that further refinements in zeoponic substrate tato (Solanum tuberosum L.) grown in a microporous would make ZPT culture a viable alternative for achieving high protube irrigation system containing isolite (a porous ceductivity in a CELSS.

Clinoptilolite is a zeolite mineral with high cation exchange capacity used in zeoponic substrates that have been proposed as a solid medium for growing plants or as a fertilizer material. The kinetics of nitrification has not been measured for NH4+ saturated zeoponic substrate. Experiments were conducted to evaluate the production of NO2- and NO3-, and nitrifier populations in zeoponic substrates. Small columns were filled with zeoponic substrate inoculated with a commercial inoculum or soil enrichment culture of nitrifying bacteria. In addition to column studies, a growth chamber study was conducted to evaluate the kinetics of nitrification in zeoponic substrates used to grow radishes (Raphanus sativus L.). The zeoponic substrate provided a readily available source of NH4+, and nitrifying bacteria were active in the substrate. Ammonium oxidation rates in column studies ranged from 5 to 10 micrograms N g-1 substrate h-1, and NO2- oxidation rates were 2 to 9.5 micrograms N g-1 substrate h-1. Rates determined from the growth chamber study were approximately 1.2 micrograms N g-1 substrate h-1. Quantities of NH4+ oxidized to NO2- and NO3- in inoculated zeoponic substrate were in excess of plant up-take. Acidification as a result of NH4+ oxidation resulted in a pH decline, and the zeoponic substrate showed limited buffering capacity.

No abstract