Scattering matrices and expansion coefficients of Martian analogue palagonite particles

We present measurements of ratios of elements of the scattering matrix of Martian analogue palagonite particles for scattering angles ranging from 3 to 174 degrees and a wavelength of 632.8 nm. To facilitate the use of these measurements in radiative transfer calculations we have devised a method that enables us to obtain, from these measurements, a normalized synthetic scattering matrix covering the complete scattering angle range from 0 to 180 degrees. Our method is based on employing the coefficients of the expansions of scattering matrix elements into generalized spherical functions. The synthetic scattering matrix elements and/or the expansion coefficients obtained in this way, can be used to include multiple scattering by these irregularly shaped particles in (polarized) radiative transfer calculations, such as calculations of sunlight that is scattered in the dusty Martian atmosphere.Comment: 34 pages 7 figures 1 tabl

The development and technology transfer of software engineering technology at NASA. Johnson Space Center

The United State's big space projects of the next decades, such as Space Station and the Human Exploration Initiative, will need the development of many millions of lines of mission critical software. NASA-Johnson (JSC) is identifying and developing some of the Computer Aided Software Engineering (CASE) technology that NASA will need to build these future software systems. The goal is to improve the quality and the productivity of large software development projects. New trends are outlined in CASE technology and how the Software Technology Branch (STB) at JSC is endeavoring to provide some of these CASE solutions for NASA is described. Key software technology components include knowledge-based systems, software reusability, user interface technology, reengineering environments, management systems for the software development process, software cost models, repository technology, and open, integrated CASE environment frameworks. The paper presents the status and long-term expectations for CASE products. The STB's Reengineering Application Project (REAP), Advanced Software Development Workstation (ASDW) project, and software development cost model (COSTMODL) project are then discussed. Some of the general difficulties of technology transfer are introduced, and a process developed by STB for CASE technology insertion is described

Observing Ice Sublimation From Water-Doped Lunar Simulant at Cryogenic Temperatures

NASA's Resource Prospector (RP) mission is intended to characterize the three-dimensional nature of volatiles in lunar polar and permanently shadowed regions. The Near-Infrared Volatile Spectrometer System (NIRVSS) observes while a drill penetrates to a maximum depth of 1 m. Any 10 cm increment of soil identified as containing water ice can be delivered to a heating crucible with the evolved gas delivered to a gas chromatograph / mass spectrometer. NIRVSS consists of two components; a spectrometer box (SB) and bracket assembly (BA), connected by two fiber optic cables. The SB contains separate short- and long-wavelength spectrometers, SW and LW respectively, that collectively span the 1600-3400 nm range. The BA contains an IR emitter (lamp), drill observation camera (DOC, 2048 x 2048 CMOS detector), 8 different wavelength LEDs, and a longwave calibration sensor (LCS) measuring the surface emissivity at four IR wavelengths. Tests of various RP sub-systems have been under-taken in a large cryo-vacuum chamber at Glenn Re-search Center. The chamber accommodates a tube (1.2 m high x 25.4 cm diameter) filled with lunar simulant, NU-LHT-3M, prepared with known abundances of water. Thermocouples are embedded at different depths, and also across the surface of the soil tube. In the chamber the tube is cooled with LN2 as the pressure is reduced to approx. 5-6x10(exp -6) Torr. For the May 2016 tests two soil tubes were prepared with initially 2.5 Wt.% water. The shroud surrounding the soil tube was held at different temperatures for each tube to simulate a warm and cold lunar environment. Table 1 provides a summary of experimental conditions and Figure 1 shows the nominal view of the NIRVSS components, the drill foot, and the top of the soil tube. Once the average soil temperature reached approx. 178 K, drilling commenced. During drilling activities NIRVSS was alternating between obtaining spectra and obtaining images. Here we discuss NIRVSS spectral data obtained during controlled drill percussions

Ices on the Satellites of Jupiter, Saturn, and Uranus

Three satellites of Jupiter, seven satellites of Saturn, and five satellites of Uranus show spectroscopic evidence of H2O ice on their surfaces, although other details of their surfaces are highly diverse. The icy surfaces contain contaminants of unknown composition in varying degrees of concentration, resulting in coloration and large differences in albedo. In addition to H2O, Europa has frozen SO2, and Ganymede has O2 in the surface; in both of these cases external causes are implicated in the deposition or formation of these trace components. Variations in ice exposure across the surfaces of the satellites are measured from the spectroscopic signatures. While H2O ice occurs on the surfaces of many satellites, the range of bulk densities of these bodies shows that its contribution to their overall compositions is highly variable from one object to another

Effect of Insecticides and Plutella xylostella (Lepidoptera: Plutellidae) Genotype on a Predator and Parasitoid and Implications for the Evolution of Insecticide Resistance

In the laboratory and in cages in the greenhouse, we evaluated the toxicity of two insecticides (lambda-cyhalothrin and spinosad) on the parasitoid, Diadegma insulare (Cresson), and the predator, Coleomegilla maculate (DeGeer), both natural enemies of the diamondback moth, Plutella xylostella (L.). Lambda-cyhalothrin was very toxic to both natural enemies. Spinosad was less toxic to C. maculata adults and larvae, and slightly toxic to D. insulare. Both natural enemies suppressed P. xylostella populations in cages with 80% spinosad-treated and 20% nontreated plants; such suppression was not seen when lambda-cyhalothrin was used. Using broccoli, Brassica oleracea L. variety italica, a common host for P. xylostella, we also studied direct and indirect effects of both natural enemies in the presence and absence of the two insecticides and to different P. xylostella genotypes: resistant to the insecticide, susceptible, or heterozygous. Neither natural enemy could distinguish host genotype if P. xylostella were feeding on nontreated plants. They could also not distinguish between larvae feeding on spinosad-treated plants and nontreated plants, but D. insulare could distinguish between larvae feeding on lambda-cyhalothrin treated and nontreated plants. Our studies suggest that lambda-cyhalothrin has direct toxicity to these two natural enemies, can affect their host foraging and acceptance of P. xylostella and consequently would not be compatible in conserving these natural enemies in a program for suppression of P. xylostella. In contrast, our studies suggest that treatment with spinosad has much less effect on these natural enemies and would allow them to help suppress populations of P. xylostella. These findings are discussed in relation to the evolution of insecticide resistance and suppression of the pest population

Effect of Bt Broccoli or Plants Treated With Insecticides on Ovipositional Preference and Larval Survival of Plutella xylostella (Lepidoptera: Plutellidae)

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), a major pest of cruciferous crops throughout the world, has demonstrated an ability to develop resistance to many different classes of insecticides, including proteins from Bacillus thuringiensis that are expressed in plants (Bt plants). The ovipositional preferences and larval survival of strains (resistant strain, RR; heterozygous strain, RS; susceptible strain, SS) of P. xylostella to Cry1Ac-expressing broccoli or broccoli plants treated with lambda-cyhalothrin or spinosad were studied under greenhouse condition. Numbers of eggs per plant did not differ between Bt broccoli and non-Bt broccoli for Bt-RR, Bt-RS, and Bt-SS adults. Ovipositing adults (spinosad-RR, spinosad-RS, and spinosad-SS) also could not discriminate between spinosad-treated and untreated plants, and oviposition did not increase over the 13 d after spinosad treatment. For broccoli treated with lambda-cyhalothrin at the diagnostic dose of 20 ppm, all three insect strains (lc-RR, lc-RS, and lc-SS) had constant oviposition over time based on linear regressions. At the field dose of 80 ppm, the lc-RR strain had constant oviposition over time. The lc-SS susceptible strain had increasing oviposition over time, but the oviposition pattern on the nonsprayed broccoli also increased over time. Susceptible females layed fewer eggs on plants sprayed with lambda-cyhalothrin than on unsprayed plants. A residue-persistence test showed that spinosad and lambda-cyhalothrin could effectively control SS P. xylostella larvae for 7-9 d after application. These results are discussed in relation to their potential impact on insecticide resistance management strategie

Kinetic Characterization of Salmonella FliK-FlhB Interactions Demonstrates Complexity of the Type III Secretion Substrate-Specificity Switch

The bacterial flagellum is a complex macromolecular machine consisting of more than 20000 proteins, most of which must be exported from the cell via a dedicated Type III secretion apparatus. At a defined point in flagellar morphogenesis, hook completion is sensed and the apparatus switches substrate specificity type from rod and hook proteins to filament ones. How the switch works is a subject of intense interest. FIiK and F1hBs play central roles. In the present study, two optical biosensing methods were used to characterize FIiK-F1hB interactions using wild-type and two variant FlhBs from mutants with severe flagellar structural defects. Binding was found to be complex with fast and slow association and dissociation components. Surprisingly, wild-type and variant FlhBs had similar kinetic profiles and apparent affinities, which ranged between I and 10.5 μM, suggesting that the specificity switch is more complex than presently understood. Other binding experiments provided evidence for a conformational change after binding. Liquid chromatography-mass spectrometry (LC-MS) and NMR experiments were performed to identify a cyclic intermediate product whose existence supports the mechanism of autocatalytic cleavage at FlhB residue N269. The present results show that while autocatalytic cleavage is necessary for proper substrate specificity switching, it does not result in an altered interaction with FIiK. strongly suggesting the involvement of other proteins in the mechanism

Phobos as a D-type captured asteroid, spectral modeling from 0.25 to 4.0 μm

This paper describes the spectral modeling of the surface of Phobos in the wavelength range between 0.25 and 4.0 μm. We use complementary data to cover this spectral range: the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System on board the ESA Rosetta spacecraft) reflectance spectrum that Pajola et al. merged with the VSK-KRFM-ISM (Videospectrometric Camera (VSK)-Combined Radiometer and Photometer for Mars (KRFM)-Imaging Spectrometer for Mars (ISM) on board the USSR Phobos 2 spacecraft) spectra by Murchie & Erard and the IRTF (NASA Infrared Telescope Facility, Hawaii, USA) spectra published by Rivkin et al. The OSIRIS data allow the characterization of an area of Phobos covering from 86.°8 N to 90° S in latitude and from 126° W to 286° W in longitude. This corresponds chiefly to the trailing hemisphere, but with a small sampling of the leading hemisphere as well. We compared the OSIRIS results with the Trojan D-type asteroid 624 Hektor and show that the overall slope and curvature of the two bodies over the common wavelength range are very similar. This favors Phobos being a captured D-type asteroid as previously suggested. We modeled the OSIRIS data using two models, the first one with a composition that includes organic carbonaceous material, serpentine, olivine, and basalt glass, and the second one consisting of Tagish Lake meteorite and magnesium-rich pyroxene glass. The results of these models were extended to longer wavelengths to compare the VSK-KRFM-ISM and IRTF data. The overall shape of the second model spectrum between 0.25 and 4.0 μm shows curvature and an albedo level that match both the OSIRIS and Murchie & Erard data and the Rivkin et al. data much better than the first model. The large interval fit is encouraging and adds weight to this model, making it our most promising fit for Phobos. Since Tagish Lake is commonly used as a spectral analog for D-type asteroids, this provides additional support for compositional similarities between Phobos and D-type asteroids. © 2013. The American Astronomical Society. All rights reserved

Validation of statistical clustering on TES dataset using synthetic Martian spectra

In this work we present some results concerning the analysis of Thermal Emission Spectrometer (TES) data, looking at the methane Q-branch spectral signature at 1304 cm-1. Such analysis has been enabled by producing some synthetic spectral datasets, simulating the atmospheric and surface variability observed on Mars, excluding the high latitude regions. The use of synthetic spectra is aimed to provide a better comprehension of the influence that the atmospheric state vector and its composition have on the spectral behavior. This effort is important, because the TES data are characterized by a low resolution (10 cm-1) and a significant random and systematic noise which could, in principle, give results whose quality needs to be improved. We apply statistical clustering of the synthetic spectra to evaluate the effectiveness of detecting methane, and estimating its abundance