78 FR 40078 - Proposed Establishment of Class E Airspace; Cody, WY

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-03

...: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). SUMMARY: This action proposes to establish Class E airspace at the Cody VHF Omni-Directional Radio Range/Distance... proposing this action to enhance the safety and management of aircraft operations within the National...

[Genetic polymorphisms of 21 non-CODIS STR loci].

PubMed

Shao, Wei-bo; Zhang, Su-hua; Li, Li

2011-02-01

To investigate genetic polymorphisms of 21 non-CODIS STR loci in Han population from the east of China and to explore their forensic application value. Twenty-one non-CODIS STR loci, were amplified with AGCU 21+1 STR kit and DNA samples were obtained from 225 unrelated individuals of the Han population from the east of China. The PCR products were analyzed with 3130 Genetic Analyzer and genotyped with GeneMapper ID v3.2 software. The genetic data were statistically analyzed with PowerStats v12.xls and Cervus 2.0 software. The distributions of 21 non-CODIS STR loci satisfied the Hardy-Weinberg equilibration. The heterozygosity (H) distributions were 0.596-0.804, the discrimination power (DP) were 0.764-0.948, the probability of exclusion of duo-testing (PEduo) were 0.176-0.492, the probability of exclusion of trios-testing (PEtrio) were 0.334-0.663, and the polymorphic information content (PIC) were 0.522-0.807. The cumulative probability of exclusion (CPE) of duo-testing was 0.999707, the CPE of trios-testing was 0.9999994, and the cumulated discrimination power (CDP) was 0.99999999999999999994. Twenty-one non-CODIS STR loci are highly polymorphic. They can be effectively used in personal identification and paternity testing in trios cases. They can also be used as supplement in the difficult cases of diad paternity testing.

Controlled branched-chain amino acids auxotrophy in Listeria monocytogenes allows isoleucine to serve as a host signal and virulence effector

PubMed Central

Borovok, Ilya; Sigal, Nadejda

2018-01-01

Listeria monocytogenes (Lm) is a saprophyte and intracellular pathogen. Transition to the pathogenic state relies on sensing of host-derived metabolites, yet it remains unclear how these are recognized and how they mediate virulence gene regulation. We previously found that low availability of isoleucine signals Lm to activate the virulent state. This response is dependent on CodY, a global regulator and isoleucine sensor. Isoleucine-bound CodY represses metabolic pathways including branched-chain amino acids (BCAA) biosynthesis, however under BCAA depletion, as occurs during infection, BCAA biosynthesis is upregulated and isoleucine-unbound CodY activates virulence genes. While isoleucine was revealed as an important input signal, it was not identified how internal levels are controlled during infection. Here we show that Lm regulates BCAA biosynthesis via CodY and via a riboregulator located upstream to the BCAA biosynthesis genes, named Rli60. rli60 is transcribed when BCAA levels drop, forming a ribosome-mediated attenuator that cis-regulates the downstream genes according to BCAA supply. Notably, we found that Rli60 restricts BCAA production, essentially starving Lm, a mechanism that is directly linked to virulence, as it controls the internal isoleucine pool and thereby CodY activity. This controlled BCAA auxotrophy likely evolved to enable isoleucine to serve as a host signal and virulence effector. PMID:29529043

Controlled branched-chain amino acids auxotrophy in Listeria monocytogenes allows isoleucine to serve as a host signal and virulence effector.

PubMed

Brenner, Moran; Lobel, Lior; Borovok, Ilya; Sigal, Nadejda; Herskovits, Anat A

2018-03-01

Listeria monocytogenes (Lm) is a saprophyte and intracellular pathogen. Transition to the pathogenic state relies on sensing of host-derived metabolites, yet it remains unclear how these are recognized and how they mediate virulence gene regulation. We previously found that low availability of isoleucine signals Lm to activate the virulent state. This response is dependent on CodY, a global regulator and isoleucine sensor. Isoleucine-bound CodY represses metabolic pathways including branched-chain amino acids (BCAA) biosynthesis, however under BCAA depletion, as occurs during infection, BCAA biosynthesis is upregulated and isoleucine-unbound CodY activates virulence genes. While isoleucine was revealed as an important input signal, it was not identified how internal levels are controlled during infection. Here we show that Lm regulates BCAA biosynthesis via CodY and via a riboregulator located upstream to the BCAA biosynthesis genes, named Rli60. rli60 is transcribed when BCAA levels drop, forming a ribosome-mediated attenuator that cis-regulates the downstream genes according to BCAA supply. Notably, we found that Rli60 restricts BCAA production, essentially starving Lm, a mechanism that is directly linked to virulence, as it controls the internal isoleucine pool and thereby CodY activity. This controlled BCAA auxotrophy likely evolved to enable isoleucine to serve as a host signal and virulence effector.

Lower Cody Shale (Niobrara equivalent) in the Bighorn Basin, Wyoming and Montana: thickness, distribution, and source rock potential

USGS Publications Warehouse

Finn, Thomas M.

2014-01-01

The lower shaly member of the Cody Shale in the Bighorn Basin, Wyoming and Montana is Coniacian to Santonian in age and is equivalent to the upper part of the Carlile Shale and basal part of the Niobrara Formation in the Powder River Basin to the east. The lower Cody ranges in thickness from 700 to 1,200 feet and underlies much of the central part of the basin. It is composed of gray to black shale, calcareous shale, bentonite, and minor amounts of siltstone and sandstone. Sixty-six samples, collected from well cuttings, from the lower Cody Shale were analyzed using Rock-Eval and total organic carbon analysis to determine the source rock potential. Total organic carbon content averages 2.28 weight percent for the Carlile equivalent interval and reaches a maximum of nearly 5 weight percent. The Niobrara equivalent interval averages about 1.5 weight percent and reaches a maximum of over 3 weight percent, indicating that both intervals are good to excellent source rocks. S2 values from pyrolysis analysis also indicate that both intervals have a good to excellent source rock potential. Plots of hydrogen index versus oxygen index, hydrogen index versus Tmax, and S2/S3 ratios indicate that organic matter contains both Type II and Type III kerogen capable of generating oil and gas. Maps showing the distribution of kerogen types and organic richness for the lower shaly member of the Cody Shale show that it is more organic-rich and more oil-prone in the eastern and southeastern parts of the basin. Thermal maturity based on vitrinite reflectance (Ro) ranges from 0.60–0.80 percent Ro around the margins of the basin, increasing to greater than 2.0 percent Ro in the deepest part of the basin, indicates that the lower Cody is mature to overmature with respect to hydrocarbon generation.

How William F. Cody Helped Save the Buffalo without Really Trying

ERIC Educational Resources Information Center

Nesheim, David

2007-01-01

Most historians have focused their attention on two elements about the restoration of the American bison: western ranchers who started the earliest private herds and eastern conservationists who raised funds and lobbied for the creation of the first national preserves. However, no one was a more effective popularizer than William F. Cody, despite…

Disaster victim investigation recommendations from two simulated mass disaster scenarios utilized for user acceptance testing CODIS 6.0.

PubMed

Bradford, Laurie; Heal, Jennifer; Anderson, Jeff; Faragher, Nichole; Duval, Kristin; Lalonde, Sylvain

2011-08-01

Members of the National DNA Data Bank (NDDB) of Canada designed and searched two simulated mass disaster (MD) scenarios for User Acceptance Testing (UAT) of the Combined DNA Index System (CODIS) 6.0, developed by the Federal Bureau of Investigation (FBI) and the US Department of Justice. A simulated airplane MD and inland Tsunami MD were designed representing a closed and open environment respectively. An in-house software program was written to randomly generate DNA profiles from a mock Caucasian population database. As part of the UAT, these two MDs were searched separately using CODIS 6.0. The new options available for identity and pedigree searching in addition to the inclusion of mitochondrial DNA (mtDNA) and Y-STR (short tandem repeat) information in CODIS 6.0, led to rapid identification of all victims. A Joint Pedigree Likelihood Ratio (JPLR) was calculated from the pedigree searches and ranks were stored in Rank Manager providing confidence to the user in assigning an Unidentified Human Remain (UHR) to a pedigree tree. Analyses of the results indicated that primary relatives were more useful in Disaster Victim Identification (DVI) compared to secondary or tertiary relatives and that inclusion of mtDNA and/or Y-STR technologies helped to link family units together as shown by the software searches. It is recommended that UHRs have as many informative loci possible to assist with their identification. CODIS 6.0 is a valuable technological tool for rapidly and confidently identifying victims of mass disasters. Crown Copyright © 2010. Published by Elsevier Ireland Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolan, Sean Gregory; Berryman, Judy; Shackley, M. Steven

Eden projectile points associated with the Cody complex are underrepresented in the late Paleoindian record of the American Southwest. EDXRF analysis of an obsidian Eden point from a site in Sierra County, New Mexico demonstrates this artifact is from the Cerro del Medio (Valles Rhyolite) source in the Jemez Mountains. Lastly, we contextualize our results by examining variability in obsidian procurement practices beyond the Cody heartland in southcentral New Mexico.

Life on a Tricycle: A Case Study of Language Impairment from 4 to 19

ERIC Educational Resources Information Center

Brinton, Bonnie; Fujiki, Martin; Robinson, Lee A.

2005-01-01

This article presents a longitudinal case study of a child named Cody identified with specific language impairment. Cody was followed from 4 to 19 years of age, at which time he compared his social skills with those of peers: "It's like they're driving sports car and I'm on a tricycle." His initial long- and short-term intervention goals are…

Admixture and genetic relationships of Mexican Mestizos regarding Latin American and Caribbean populations based on 13 CODIS-STRs.

PubMed

Salazar-Flores, J; Zuñiga-Chiquette, F; Rubi-Castellanos, R; Álvarez-Miranda, J L; Zetina-Hérnandez, A; Martínez-Sevilla, V M; González-Andrade, F; Corach, D; Vullo, C; Álvarez, J C; Lorente, J A; Sánchez-Diz, P; Herrera, R J; Cerda-Flores, R M; Muñoz-Valle, J F; Rangel-Villalobos, H

2015-02-01

Short tandem repeats (STRs) of the combined DNA index system (CODIS) are probably the most employed markers for human identification purposes. STR databases generated to interpret DNA profiles are also helpful for anthropological purposes. In this work, we report admixture, population structure, and genetic relationships of Mexican Mestizos with respect to Latin American and Caribbean populations based on 13 CODIS-STRs. In addition, new STR population data were included from Tijuana, Baja California (Northwest, Mexico), which represents an interesting case of elevated genetic flow as a bordering city with the USA. Inter-population analyses included CODIS-STR data from 11 Mexican Mestizo, 12 Latin American and four Caribbean populations, in addition to European, Amerindian, and African genetic pools as ancestral references. We report allele frequencies and statistical parameters of forensic interest (PD, PE, Het, PIC, typical PI), for 15 STRs in Tijuana, Baja California. This Mexican border city was peculiar by the increase of African ancestry, and by presenting three STRs in Hardy-Weinberg disequilibrium, probably explained by recurrent gene flow. The Amerindian ancestry in Central and Southeast of Mexico was the greatest in Latin America (50.9-68.6%), only comparable with the North of Central America and Ecuador (48.8-56.4%), whereas the European ancestry was prevalent in South America (66.7-75%). The African ancestry in Mexico was the smallest (2.2-6.3%) in Latin America (≥ 2.6%), particularly regarding Brazil (21%), Honduras (62%), and the Caribbean (43.2-65.2%). CODIS-STRs allowed detecting significant population structure in Latin America based on greater presence of European, Amerindian, and African ancestries in Central/South America, Mexican Mestizos, and the Caribbean, respectively. Copyright © 2014 Elsevier GmbH. All rights reserved.

Repression of branched-chain amino acid synthesis in Staphylococcus aureus is mediated by isoleucine via CodY, and by a leucine-rich attenuator peptide.

PubMed

Kaiser, Julienne C; King, Alyssa N; Grigg, Jason C; Sheldon, Jessica R; Edgell, David R; Murphy, Michael E P; Brinsmade, Shaun R; Heinrichs, David E

2018-01-01

Staphylococcus aureus requires branched-chain amino acids (BCAAs; isoleucine, leucine, valine) for protein synthesis, branched-chain fatty acid synthesis, and environmental adaptation by responding to their availability via the global transcriptional regulator CodY. The importance of BCAAs for S. aureus physiology necessitates that it either synthesize them or scavenge them from the environment. Indeed S. aureus uses specialized transporters to scavenge BCAAs, however, its ability to synthesize them has remained conflicted by reports that it is auxotrophic for leucine and valine despite carrying an intact BCAA biosynthetic operon. In revisiting these findings, we have observed that S. aureus can engage in leucine and valine synthesis, but the level of BCAA synthesis is dependent on the BCAA it is deprived of, leading us to hypothesize that each BCAA differentially regulates the biosynthetic operon. Here we show that two mechanisms of transcriptional repression regulate the level of endogenous BCAA biosynthesis in response to specific BCAA availability. We identify a trans-acting mechanism involving isoleucine-dependent repression by the global transcriptional regulator CodY and a cis-acting leucine-responsive attenuator, uncovering how S. aureus regulates endogenous biosynthesis in response to exogenous BCAA availability. Moreover, given that isoleucine can dominate CodY-dependent regulation of BCAA biosynthesis, and that CodY is a global regulator of metabolism and virulence in S. aureus, we extend the importance of isoleucine availability for CodY-dependent regulation of other metabolic and virulence genes. These data resolve the previous conflicting observations regarding BCAA biosynthesis, and reveal the environmental signals that not only induce BCAA biosynthesis, but that could also have broader consequences on S. aureus environmental adaptation and virulence via CodY.

Techniques for identifying dust devils in mars pathfinder images

USGS Publications Warehouse

Metzger, S.M.; Carr, J.R.; Johnson, J. R.; Parker, T.J.; Lemmon, M.T.

2000-01-01

Image processing methods used to identify and enhance dust devil features imaged by IMP (Imager for Mars Pathfinder) are reviewed. Spectral differences, visible red minus visible blue, were used for initial dust devil searches, driven by the observation that Martian dust has high red and low blue reflectance. The Martian sky proved to be more heavily dust-laden than pre-Pathfinder predictions, based on analysis of images from the Hubble Space Telescope. As a result, these initial spectral difference methods failed to contrast dust devils with background dust haze. Imager artifacts (dust motes on the camera lens, flat-field effects caused by imperfections in the CCD, and projection onto a flat sensor plane by a convex lens) further impeded the ability to resolve subtle dust devil features. Consequently, reference images containing sky with a minimal horizon were first subtracted from each spectral filter image to remove camera artifacts and reduce the background dust haze signal. Once the sky-flat preprocessing step was completed, the red-minus-blue spectral difference scheme was attempted again. Dust devils then were successfully identified as bright plumes. False-color ratios using calibrated IMP images were found useful for visualizing dust plumes, verifying initial discoveries as vortex-like features. Enhancement of monochromatic (especially blue filter) images revealed dust devils as silhouettes against brighter background sky. Experiments with principal components transformation identified dust devils in raw, uncalibrated IMP images and further showed relative movement of dust devils across the Martian surface. A variety of methods therefore served qualitative and quantitative goals for dust plume identification and analysis in an environment where such features are obscure.

KSC-02pp1745

NASA Image and Video Library

2002-11-10

KENNEDY SPACE CENTER, FLA. - An elder of her Navaho tribe, Dorothy Cody shares the stage with her granddaughter Radmilla Cody (not shown), the 2001 Miss Navaho Nation, who is singing the "Star Spangled Banner" in her native language during a pre-launch Native American ceremony. The ceremony was part of several days' activities commemorating John B. Herrington as the first tribally enrolled Native American astronaut to fly on a Shuttle mission. Herrington is a Mission Specialist on STS-113.

Marine Structural Steel Toughness Data Bank (Abridged Edition)

DTIC Science & Technology

1990-08-31

for Table Column Headings: Break? Did specimen fracture completely? CODIc Critical COD CODi Initial COD CVN Energy Charpy V Energy Crack lgth Crack...Standard Y ear ........ .................. * Onen Test Temp KQ CODi CODIc Curve 3l degF ksi*in**0.5 mils mils in-lb/in2 L-T -166...Standard Method .... BS5762 -Standard Year . Test Temp CODIc degC mm -30 0.57 -30 0.68 -30 11.26 (continued) -not reported

The source provenance of an obsidian Eden point from Sierra County, New Mexico

DOE PAGES

Dolan, Sean Gregory; Berryman, Judy; Shackley, M. Steven

2016-01-02

Eden projectile points associated with the Cody complex are underrepresented in the late Paleoindian record of the American Southwest. EDXRF analysis of an obsidian Eden point from a site in Sierra County, New Mexico demonstrates this artifact is from the Cerro del Medio (Valles Rhyolite) source in the Jemez Mountains. Lastly, we contextualize our results by examining variability in obsidian procurement practices beyond the Cody heartland in southcentral New Mexico.

CcpA and CodY Coordinate Acetate Metabolism in Streptococcus mutans.

PubMed

Kim, Jeong Nam; Burne, Robert A

2017-04-01

In the dental caries pathogen Streptococcus mutans , phosphotransacetylase (Pta) and acetate kinase (Ack) convert pyruvate into acetate with the concomitant generation of ATP. The genes for this pathway are tightly regulated by multiple environmental and intracellular inputs, but the basis for differential expression of the genes for Pta and Ack in S. mutans had not been investigated. Here, we show that inactivation in S. mutans of ccpA or codY reduced the activity of the ackA promoter, whereas a ccpA mutant displayed elevated pta promoter activity. The interactions of CcpA with the promoter regions of both genes were observed using electrophoretic mobility shift and DNase protection assays. CodY bound to the ackA promoter region but only in the presence of branched-chain amino acids (BCAAs). DNase footprinting revealed that the upstream region of both genes contains two catabolite-responsive elements ( cre1 and cre2 ) that can be bound by CcpA. Notably, the cre2 site of ackA overlaps with a CodY-binding site. The CcpA- and CodY-binding sites in the promoter region of both genes were further defined by site-directed mutagenesis. Some differences between the reported consensus CodY binding site and the region protected by S. mutans CodY were noted. Transcription of the pta and ackA genes in the ccpA mutant strain was markedly different at low pH relative to transcription at neutral pH. Thus, CcpA and CodY are direct regulators of transcription of ackA and pta in S. mutans that optimize acetate metabolism in response to carbohydrate, amino acid availability, and environmental pH. IMPORTANCE The human dental caries pathogen Streptococcus mutans is remarkably adept at coping with extended periods of carbohydrate limitation during fasting periods. The phosphotransacetylase-acetate kinase (Pta-Ack) pathway in S. mutans modulates carbohydrate flux and fine-tunes the ability of the organisms to cope with stressors that are commonly encountered in the oral cavity. Here, we show that CcpA controls transcription of the pta and ackA genes via direct interaction with the promoter regions of both genes and that branched-chain amino acids (BCAAs), particularly isoleucine, enhance the ability of CodY to bind to the promoter region of the ackA gene. A working model is proposed to explain how regulation of pta and ackA genes by these allosterically controlled regulatory proteins facilitates proper carbon flow and energy production, which are essential functions during infection and pathogenesis as carbohydrate and amino acid availability continually fluctuate. Copyright © 2017 American Society for Microbiology.

Searching for a Different Understanding of Operational Art

DTIC Science & Technology

2016-05-26

that “hampered by 35 Bruce Menning, “Operational Art’s Origins,” in Historical Perspectives of the Operational Art, ed. Michael D. Krause and R. Cody...war or theater of 43 Clayton Newell, “Introduction,” in On Operational Art, ed. Clayton Newell and Michael Krause (Washington, DC: US Army Center of...Menning, Bruce. “Operational Art’s Origins.” In Historical Perspectives of the Operational Art, edited by Michael D. Krause and R. Cody Phillips, 3

Integrative Genomic Analysis Identifies Isoleucine and CodY as Regulators of Listeria monocytogenes Virulence

PubMed Central

Lobel, Lior; Sigal, Nadejda; Borovok, Ilya; Ruppin, Eytan; Herskovits, Anat A.

2012-01-01

Intracellular bacterial pathogens are metabolically adapted to grow within mammalian cells. While these adaptations are fundamental to the ability to cause disease, we know little about the relationship between the pathogen's metabolism and virulence. Here we used an integrative Metabolic Analysis Tool that combines transcriptome data with genome-scale metabolic models to define the metabolic requirements of Listeria monocytogenes during infection. Twelve metabolic pathways were identified as differentially active during L. monocytogenes growth in macrophage cells. Intracellular replication requires de novo synthesis of histidine, arginine, purine, and branch chain amino acids (BCAAs), as well as catabolism of L-rhamnose and glycerol. The importance of each metabolic pathway during infection was confirmed by generation of gene knockout mutants in the respective pathways. Next, we investigated the association of these metabolic requirements in the regulation of L. monocytogenes virulence. Here we show that limiting BCAA concentrations, primarily isoleucine, results in robust induction of the master virulence activator gene, prfA, and the PrfA-regulated genes. This response was specific and required the nutrient responsive regulator CodY, which is known to bind isoleucine. Further analysis demonstrated that CodY is involved in prfA regulation, playing a role in prfA activation under limiting conditions of BCAAs. This study evidences an additional regulatory mechanism underlying L. monocytogenes virulence, placing CodY at the crossroads of metabolism and virulence. PMID:22969433

The metabolic regulator CodY links L. monocytogenes metabolism to virulence by directly activating the virulence regulatory gene, prfA

PubMed Central

Lobel, Lior; Sigal, Nadejda; Borovok, Ilya; Belitsky, Boris R.; Sonenshein, Abraham L.; Herskovits, Anat A.

2015-01-01

Summary Metabolic adaptations are critical to the ability of bacterial pathogens to grow within host cells and are normally preceded by sensing of host-specific metabolic signals, which in turn can influence the pathogen's virulence state. Previously, we reported that the intracellular bacterial pathogen Listeria monocytogenes responds to low availability of branched-chain amino acids (BCAA) within mammalian cells by up-regulating both BCAA biosynthesis and virulence genes. The induction of virulence genes required the BCAA-responsive transcription regulator, CodY, but the molecular mechanism governing this mode of regulation was unclear. In this report, we demonstrate that CodY directly binds the coding sequence of the L. monocytogenes master virulence activator gene, prfA, 15 nt downstream of its start codon, and that this binding results in up-regulation of prfA transcription specifically under low concentrations of BCAA. Mutating this site abolished CodY binding and reduced prfA transcription in macrophages, and attenuated bacterial virulence in mice. Notably, the mutated binding site did not alter prfA transcription or PrfA activity under other conditions that are known to activate PrfA, such as during growth in the presence of glucose-1-phosphate. This study highlights the tight crosstalk between L. monocytogenes metabolism and virulence' while revealing novel features of CodY-mediated regulation. PMID:25430920

CodY Promotes Sporulation and Enterotoxin Production by Clostridium perfringens Type A Strain SM101

PubMed Central

Li, Jihong; Freedman, John C.; Evans, Daniel R.

2017-01-01

ABSTRACT Clostridium perfringens type D strains cause enterotoxemia and enteritis in livestock via epsilon toxin production. In type D strain CN3718, CodY was previously shown to increase the level of epsilon toxin production and repress sporulation. C. perfringens type A strains producing C. perfringens enterotoxin (CPE) cause human food poisoning and antibiotic-associated diarrhea. Sporulation is critical for C. perfringens type A food poisoning since spores contribute to transmission and resistance in the harsh food environment and sporulation is essential for CPE production. Therefore, the current study asked whether CodY also regulates sporulation and CPE production in SM101, a derivative of C. perfringens type A food-poisoning strain NCTC8798. An isogenic codY-null mutant of SM101 showed decreased levels of spore formation, along with lower levels of CPE production. A complemented strain recovered wild-type levels of both sporulation and CPE production. When this result was coupled with the earlier results obtained with CN3718, it became apparent that CodY regulation of sporulation varies among different C. perfringens strains. Results from quantitative reverse transcriptase PCR analysis clearly demonstrated that, during sporulation, codY transcript levels remained high in SM101 but rapidly declined in CN3718. In addition, abrB gene expression patterns varied significantly between codY-null mutants of SM101 and CN3718. Compared to the levels in their wild-type parents, the level of abrB gene expression decreased in the CN3718 codY-null mutant strain but significantly increased in the SM101 codY-null mutant strain, demonstrating CodY-dependent regulation differences in abrB expression between these two strains. This difference appears to be important since overexpression of the abrB gene in SM101 reduced the levels of sporulation and enterotoxin production, supporting the involvement of AbrB repression in regulating C. perfringens sporulation. PMID:28052992

Gusev Dust Devil Movie, Sol 459 (Enhanced)

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows a dust devil scooting across a plain inside Gusev Crater on Mars as seen from the NASA rover Spirit's hillside vantage point during the rover's 459th martian day, or sol (April 18, 2005). The individual images were taken about 20 seconds apart by Spirit's navigation camera, and the contrast has been enhanced for anything in the images that changes from frame to frame, that is, for the dust devil.

The movie results from a new way of watching for dust devils, which are whirlwinds that hoist dust from the surface into the air. Spirit began seeing dust devils in isolated images in March 2005. At first, the rover team relied on luck. It might catch a dust devil in an image or it might miss by a few minutes. Using the new detection strategy, the rover takes a series of 21 images. Spirit sends a few of them to Earth, as well as little thumbnail images of all of them. Team members use the 3 big images and all the small images to decide whether the additional big images have dust devils. For this movie, they specifically told Spirit to send back frames that they knew had dust devils.

The images were processed in three steps. All images were calibrated to remove known camera artifacts. The images were then processed to remove stationary objects. The result is a gray scene showing only features that change with time. The final step combined the original image with the image that shows only moving features, showing the martian scene and the enhanced dust devils.

Scientists expected dust devils since before Spirit landed. The landing area inside Gusev Crater is filled with dark streaks left behind when dust devils pick dust up from an area. It is also filled with bright 'hollows,' which are dust-filled miniature craters. Dust covers most of the terrain. Winds flow into and out of Gusev crater every day. The Sun heats the surface so that the surface is warm to the touch even though the atmosphere at 2 meters (6 feet) above the surface would be chilly. That temperature contrast causes convection. Mixing the dust, winds, and convection should trigger dust devils.

Scientists will use the images to study several things. Tracking the dust devils tells which way the wind blows at different times of day. Statistics on the size of typical dust devils will help with estimates of how much dust they pump into the atmosphere every day. By watching individual dust devils change as they go over more-dusty and less-dusty terrain, researchers can learn about the turbulent motion near the surface. Ultimately, that motion of wind and dust near the surface relates these small dust devils with Mars' large dust storms.

Gusev Dust Devil Movie, Sol 456 (Enhanced)

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows a dust devil scooting across a plain inside Gusev Crater on Mars as seen from the NASA rover Spirit's hillside vantage point during the rover's 456th martian day, or sol (April 15, 2005). The individual images were taken about 20 seconds apart by Spirit's navigation camera, and the contrast has been enhanced for anything in the images that changes from frame to frame, that is, for the dust devil.

The movie results from a new way of watching for dust devils, which are whirlwinds that hoist dust from the surface into the air. Spirit began seeing dust devils in isolated images in March 2005. At first, the rover team relied on luck. It might catch a dust devil in an image or it might miss by a few minutes. Using the new detection strategy, the rover takes a series of 21 images. Spirit sends a few of them to Earth, as well as little thumbnail images of all of them. Team members use the 3 big images and all the small images to decide whether the additional big images have dust devils. For this movie, they specifically told Spirit to send back frames that they knew had dust devils.

The images were processed in three steps. All images were calibrated to remove known camera artifacts. The images were then processed to remove stationary objects. The result is a gray scene showing only features that change with time. The final step combined the original image with the image that shows only moving features, showing the martian scene and the enhanced dust devils.

Scientists expected dust devils since before Spirit landed. The landing area inside Gusev Crater is filled with dark streaks left behind when dust devils pick dust up from an area. It is also filled with bright 'hollows,' which are dust-filled miniature craters. Dust covers most of the terrain. Winds flow into and out of Gusev crater every day. The Sun heats the surface so that the surface is warm to the touch even though the atmosphere at 2 meters (6 feet) above the surface would be chilly. That temperature contrast causes convection. Mixing the dust, winds, and convection should trigger dust devils.

Scientists will use the images to study several things. Tracking the dust devils tells which way the wind blows at different times of day. Statistics on the size of typical dust devils will help with estimates of how much dust they pump into the atmosphere every day. By watching individual dust devils change as they go over more-dusty and less-dusty terrain, researchers can learn about the turbulent motion near the surface. Ultimately, that motion of wind and dust near the surface relates these small dust devils with Mars' large dust storms.

Activities commemorating John B. Herrington as first Native American astronaut

NASA Technical Reports Server (NTRS)

2002-01-01

KENNEDY SPACE CENTER, FLA. - An elder of her Navaho tribe, Dorothy Cody shares the stage with her granddaughter Radmilla Cody (not shown), the 2001 Miss Navaho Nation, who is singing the 'Star Spangled Banner' in her native language during a pre-launch Native American ceremony. The ceremony was part of several days' activities commemorating John B. Herrington as the first tribally enrolled Native American astronaut to fly on a Shuttle mission. Herrington is a Mission Specialist on STS-113.

Automatic detection of typical dust devils from Mars landscape images

NASA Astrophysics Data System (ADS)

Ogohara, Kazunori; Watanabe, Takeru; Okumura, Susumu; Hatanaka, Yuji

2018-02-01

This paper presents an improved algorithm for automatic detection of Martian dust devils that successfully extracts tiny bright dust devils and obscured large dust devils from two subtracted landscape images. These dust devils are frequently observed using visible cameras onboard landers or rovers. Nevertheless, previous research on automated detection of dust devils has not focused on these common types of dust devils, but on dust devils that appear on images to be irregularly bright and large. In this study, we detect these common dust devils automatically using two kinds of parameter sets for thresholding when binarizing subtracted images. We automatically extract dust devils from 266 images taken by the Spirit rover to evaluate our algorithm. Taking dust devils detected by visual inspection to be ground truth, the precision, recall and F-measure values are 0.77, 0.86, and 0.81, respectively.

Gusev Dust Devil Movie, Sol 456 (Plain and Isolated)

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows a dust devil scooting across a plain inside Gusev Crater on Mars as seen from the NASA rover Spirit's hillside vantage point during the rover's 456th martian day, or sol (April 15, 2005). The individual images were taken about 20 seconds apart by Spirit's navigation camera. Each frame in this movie has the raw image on the top half and a processed version in the lower half that enhances contrast and removes stationary objects, producing an image that is uniformly gray except for features that change from frame to frame.

The movie results from a new way of watching for dust devils, which are whirlwinds that hoist dust from the surface into the air. Spirit began seeing dust devils in isolated images in March 2005. At first, the rover team relied on luck. It might catch a dust devil in an image or it might miss by a few minutes. Using the new detection strategy, the rover takes a series of 21 images. Spirit sends a few of them to Earth, as well as little thumbnail images of all of them. Team members use the 3 big images and all the small images to decide whether the additional big images have dust devils. For this movie, they specifically told Spirit to send back frames that they knew had dust devils.

Scientists expected dust devils since before Spirit landed. The landing area inside Gusev Crater is filled with dark streaks left behind when dust devils pick dust up from an area. It is also filled with bright 'hollows,' which are dust-filled miniature craters. Dust covers most of the terrain. Winds flow into and out of Gusev crater every day. The Sun heats the surface so that the surface is warm to the touch even though the atmosphere at 2 meters (6 feet) above the surface would be chilly. That temperature contrast causes convection. Mixing the dust, winds, and convection should trigger dust devils.

Scientists will use the images to study several things. Tracking the dust devils tells which way the wind blows at different times of day. Statistics on the size of typical dust devils will help with estimates of how much dust they pump into the atmosphere every day. By watching individual dust devils change as they go over more-dusty and less-dusty terrain, researchers can learn about the turbulent motion near the surface. Ultimately, that motion of wind and dust near the surface relates these small dust devils with Mars' large dust storms.

Gusev Dust Devil Movie, Sol 459 (Plain and Isolated)

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows a dust devil scooting across a plain inside Gusev Crater on Mars as seen from the NASA rover Spirit's hillside vantage point during the rover's 459th martian day, or sol (April 18, 2005). The individual images were taken about 20 seconds apart by Spirit's navigation camera. Each frame in this movie has the raw image on the top half and a processed version in the lower half that enhances contrast and removes stationary objects, producing an image that is uniformly gray except for features that change from frame to frame.

The movie results from a new way of watching for dust devils, which are whirlwinds that hoist dust from the surface into the air. Spirit began seeing dust devils in isolated images in March 2005. At first, the rover team relied on luck. It might catch a dust devil in an image or it might miss by a few minutes. Using the new detection strategy, the rover takes a series of 21 images. Spirit sends a few of them to Earth, as well as little thumbnail images of all of them. Team members use the 3 big images and all the small images to decide whether the additional big images have dust devils. For this movie, they specifically told Spirit to send back frames that they knew had dust devils.

Scientists expected dust devils since before Spirit landed. The landing area inside Gusev Crater is filled with dark streaks left behind when dust devils pick dust up from an area. It is also filled with bright 'hollows,' which are dust-filled miniature craters. Dust covers most of the terrain. Winds flow into and out of Gusev crater every day. The Sun heats the surface so that the surface is warm to the touch even though the atmosphere at 2 meters (6 feet) above the surface would be chilly. That temperature contrast causes convection. Mixing the dust, winds, and convection should trigger dust devils.

Scientists will use the images to study several things. Tracking the dust devils tells which way the wind blows at different times of day. Statistics on the size of typical dust devils will help with estimates of how much dust they pump into the atmosphere every day. By watching individual dust devils change as they go over more-dusty and less-dusty terrain, researchers can learn about the turbulent motion near the surface. Ultimately, that motion of wind and dust near the surface relates these small dust devils with Mars' large dust storms.

Thick sequences of silicate and carbonate rocks of sedimentary origin in North America an interim report

USGS Publications Warehouse

Love, John David

1956-01-01

Thick sequences of silicate and carbonate rocks of sedimentary origin have been investigated in 64 areas in North America. The areas containing the thickest and most homogeneous stratigraphic sections more than 1,000 feet thick, buried at depths greater than 10,000 feet are: 1. Uinta Basin, Utah, where the Mancos shale is 1,300 to 5,000 feet thick, the Weber sandstone is 1,000 to 1,600 feet thick, and Mississippian limestones are 1,000 to 1,500 feet thick. 2. Washakie Basin, Wyoming, and Sand Wash Ba.sin, Colorado, where the Lewis shale is 1,000 to 2,000 feet thick and the Cody-Mancos shale is 4,500 to 5,500 feet thick. 3. Green River Basin, Wyoming, where the Cody-Hilliard-Baxter-Mancos shale sequence averages more than 3,000 feet, the siltstone and shale of the Chugwater formation totals 1,000 feet, and the Madison limestone ranges from 1,000 to 1,400 feet thick. 4. Red Desert (Great Divide) Basin, Wyoming, where the Cody shale is 4,000 feet thick. 5. Hanna Basin, Wyoming, where the Steele shale is 4,500 feet thick. 6. Wind River Basin, Wyoming, where the Cody shale is 3,600 to 5,000 feet thick. Geochemical characteristics of these rocks in these areas are poorly known but are being investigated. A summary of the most pertinent recent ana1yses is presented.

Dust as a versatile matter for high-temperature plasma diagnostic.

PubMed

Wang, Zhehui; Ticos, Catalin M

2008-10-01

Dust varies from a few nanometers to a fraction of a millimeter in size. Dust also offers essentially unlimited choices in material composition and structure. The potential of dust for high-temperature plasma diagnostic is largely unfulfilled yet. The principles of dust spectroscopy to measure internal magnetic field, microparticle tracer velocimetry to measure plasma flow, and dust photometry to measure heat flux are described. Two main components of the different dust diagnostics are a dust injector and a dust imaging system. The dust injector delivers a certain number of dust grains into a plasma. The imaging system collects and selectively detects certain photons resulted from dust-plasma interaction. One piece of dust gives the local plasma quantity, a collection of dust grains together reveals either two-dimensional (using only one or two imaging cameras) or three-dimensional (using two or more imaging cameras) structures of the measured quantity. A generic conceptual design suitable for all three types of dust diagnostics is presented.

Model of Image Artifacts from Dust Particles

NASA Technical Reports Server (NTRS)

Willson, Reg

2008-01-01

A mathematical model of image artifacts produced by dust particles on lenses has been derived. Machine-vision systems often have to work with camera lenses that become dusty during use. Dust particles on the front surface of a lens produce image artifacts that can potentially affect the performance of a machine-vision algorithm. The present model satisfies a need for a means of synthesizing dust image artifacts for testing machine-vision algorithms for robustness (or the lack thereof) in the presence of dust on lenses. A dust particle can absorb light or scatter light out of some pixels, thereby giving rise to a dark dust artifact. It can also scatter light into other pixels, thereby giving rise to a bright dust artifact. For the sake of simplicity, this model deals only with dark dust artifacts. The model effectively represents dark dust artifacts as an attenuation image consisting of an array of diffuse darkened spots centered at image locations corresponding to the locations of dust particles. The dust artifacts are computationally incorporated into a given test image by simply multiplying the brightness value of each pixel by a transmission factor that incorporates the factor of attenuation, by dust particles, of the light incident on that pixel. With respect to computation of the attenuation and transmission factors, the model is based on a first-order geometric (ray)-optics treatment of the shadows cast by dust particles on the image detector. In this model, the light collected by a pixel is deemed to be confined to a pair of cones defined by the location of the pixel s image in object space, the entrance pupil of the lens, and the location of the pixel in the image plane (see Figure 1). For simplicity, it is assumed that the size of a dust particle is somewhat less than the diameter, at the front surface of the lens, of any collection cone containing all or part of that dust particle. Under this assumption, the shape of any individual dust particle artifact is the shape (typically, circular) of the aperture, and the contribution of the particle to the attenuation factor for a given pixel is the fraction of the cross-sectional area of the collection cone occupied by the particle. Assuming that dust particles do not overlap, the net transmission factor for a given pixel is calculated as one minus the sum of attenuation factors contributed by all dust particles affecting that pixel. In a test, the model was used to synthesize attenuation images for random distributions of dust particles on the front surface of a lens at various relative aperture (F-number) settings. As shown in Figure 2, the attenuation images resembled dust artifacts in real test images recorded while the lens was aimed at a white target.

Guanine limitation results in CodY-dependent and -independent alteration of Staphylococcus aureus physiology and gene expression.

PubMed

King, Alyssa N; Borkar, Samiksha; Samuels, David J; Batz, Zachary; Bulock, Logan; Sadykov, Marat R; Bayles, Kenneth W; Brinsmade, Shaun R

2018-04-30

In Staphylococcus aureus , the global transcriptional regulator CodY modulates the expression of hundreds of genes in response to the availability of GTP and the branched-chain amino acids isoleucine, leucine, and valine (ILV). CodY DNA-binding activity is high when GTP and ILV are abundant. When GTP and ILV are limited, CodY's affinity for DNA drops, altering expression of CodY regulated targets. In this work, we investigated the impact of guanine nucleotides on S. aureus physiology and CodY activity by constructing a guaA null mutant (Δ guaA ). De novo biosynthesis of guanine monophosphate is abolished due to the guaA mutation; thus, the mutant cells require exogenous guanosine for growth. We also found that CodY activity was reduced when we knocked out guaA , activating the Agr two-component system and increasing secreted protease activity. Notably, in a rich, complex medium, we detected an increase in alternative sigma factor B activity in the Δ guaA mutant, which results in a 5-fold increase in production of the antioxidant pigment staphyloxanthin. Under biologically relevant flow conditions, Δ guaA cells failed to form robust biofilms when limited for guanine or guanosine. RNA-seq analysis of S. aureus transcriptome during growth in guanosine-limited chemostats revealed substantial CodY-dependent and -independent alteration of gene expression profiles. Importantly, these changes increase production of proteases and δ-toxin, suggesting that S. aureus exhibits a more invasive lifestyle when limited for guanosine. Further, gene-products upregulated under GN limitation, including those necessary for lipoic acid biosynthesis and sugar transport, may prove to be useful drug targets for treating Gram-positive infections. Importance Staphylococcus aureus infections impose a serious economic burden on healthcare facilities and patients because of the emergence of strains resistant to last-line antibiotics. Understanding the physiological processes governing fitness and virulence of S. aureus in response to environmental cues is critical for developing efficient diagnostics and treatments. De novo purine biosynthesis is essential for both fitness and virulence in S. aureus , since inhibiting production cripples S. aureus 's ability to cause infection. Here, we corroborate these findings and show that blocking guanine nucleotide synthesis severely affects S. aureus fitness by altering metabolic and virulence gene expression. Characterizing pathways and gene products upregulated in response to guanine limitation can aid in the development of novel adjuvant strategies to combat S. aureus infections. Copyright © 2018 American Society for Microbiology.

Evaluation of forensic genetic parameters of 12 STR loci in the Korean population using the InvestigatorⓇ HDplex kit.

PubMed

Jung, Ju Yeon; Kim, Eun Hye; Oh, Yu-Li; Park, Hyun-Chul; Hwang, Jung Ho; Lim, Si-Keun

2017-09-01

We genotyped and calculated the forensic parameters of 10 non-CODIS loci and 2 CODIS loci of 990 Korean individuals using the Investigator Ⓡ HDplex kit. No significant deviations from Hardy-Weinberg equilibrium (after Bonferroni correction for multiple testing) or genetic linkage disequilibrium were observed. The calculated matching probability and power of discrimination ranged from 0.0080 to 0.2014, and 0.7986 to 0.9920, respectively. We conclude that the markers of the kit are highly informative corroborative tools for forensic DNA analysis.

Dust devil vortices seen by the Mars Pathfinder camera

USGS Publications Warehouse

Metzger, S.M.; Carr, J.R.; Johnson, J. R.; Parker, T.J.; Lemmon, M.T.

1999-01-01

Discovery of dust devil vortices in Mars Pathfinder (MPF) images reveals a dust entrainment mechanism at work on Mars. Scattering of visible light by dust in the Martian atmosphere creates a pronounced haze, preventing conventional image processing from displaying dust plumes. Spectral differencing techniques have enhanced five localized dust plumes from the general haze in images acquired near midday, which we determine to be dust devils. Processing of 440 nm images highlights dust devils as distinct occultation features against the horizon. The dust devils are interpreted to be 14-79 m wide, 46-350 m tall, travel at 0.5-4.6 m/s, with dust loading of 7E-5 kg m-3, relative to the general haze of 9E-8 kg m-3, and total particulate transport of 2.2 - 700 kg. The vortices match predictions from terrestrial analog studies. Copyright 1999 by the American Geophysical Union.

Stratigraphic cross sections of the Niobrara interval of the Cody Shale and associated rocks in the Wind River Basin, central Wyoming

USGS Publications Warehouse

Finn, Thomas M.

2017-02-07

The Wind River Basin in Wyoming is one of many structural and sedimentary basins that formed in the Rocky Mountain foreland during the Laramide orogeny. The basin is nearly 200 miles long, 70 miles wide, and encompasses about 7,400 square miles in central Wyoming. The basin is bounded by the Washakie Range, Owl Creek uplift, and southern Bighorn Mountains on the north, the Casper arch on the east, the Granite Mountains on the south, and Wind River Range on the west.Many important conventional oil and gas fields producing from reservoirs ranging in age from Mississippian through Tertiary have been discovered in this basin. In addition, an extensive unconventional overpressured basin-centered gas accumulation has been identified in Cretaceous and Tertiary strata in the deeper parts of the basin. It has long been suggested that various Upper Cretaceous marine shales, including the Cody Shale, are the principal hydrocarbon source rocks for many of these accumulations. With recent advances and success in horizontal drilling and multistage fracture stimulation, there has been an increase in exploration and completion of wells in these marine shales in other Rocky Mountain Laramide basins that were traditionally thought of only as hydrocarbon source rocks.The two stratigraphic cross sections presented in this report were constructed as part of a project carried out by the U.S. Geological Survey to characterize and evaluate the undiscovered continuous (unconventional) oil and gas resources of the Niobrara interval of the Upper Cretaceous Cody Shale in the Wind River Basin in central Wyoming. The primary purpose of the cross sections is to show the stratigraphic relationship of the Niobrara equivalent strata and associated rocks in the lower part of the Cody Shale in the Wind River Basin. These two cross sections were constructed using borehole geophysical logs from 37 wells drilled for oil and gas exploration and production, and one surface section along East Sheep Creek near Shotgun Butte in the northwestern part of the basin. Both lines originate at the East Sheep Creek surface section and end near Clarkson Hill in the extreme southeastern part of the basin. The stratigraphic interval extends from the upper part of the Frontier Formation to the middle part of the Cody Shale. The datum is the base of the “chalk kick” marker bed, a distinctive resistivity peak or zone in the lower part of the Cody Shale. A gamma ray and (or) spontaneous potential (SP) log was used in combination with a resistivity log to identify and correlate units. Marine molluscan index fossils collected from nearby outcrop sections were projected into the subsurface to help determine the relative ages of the strata and aid in correlation.

Short-read, high-throughput sequencing technology for STR genotyping

PubMed Central

Bornman, Daniel M.; Hester, Mark E.; Schuetter, Jared M.; Kasoji, Manjula D.; Minard-Smith, Angela; Barden, Curt A.; Nelson, Scott C.; Godbold, Gene D.; Baker, Christine H.; Yang, Boyu; Walther, Jacquelyn E.; Tornes, Ivan E.; Yan, Pearlly S.; Rodriguez, Benjamin; Bundschuh, Ralf; Dickens, Michael L.; Young, Brian A.; Faith, Seth A.

2013-01-01

DNA-based methods for human identification principally rely upon genotyping of short tandem repeat (STR) loci. Electrophoretic-based techniques for variable-length classification of STRs are universally utilized, but are limited in that they have relatively low throughput and do not yield nucleotide sequence information. High-throughput sequencing technology may provide a more powerful instrument for human identification, but is not currently validated for forensic casework. Here, we present a systematic method to perform high-throughput genotyping analysis of the Combined DNA Index System (CODIS) STR loci using short-read (150 bp) massively parallel sequencing technology. Open source reference alignment tools were optimized to evaluate PCR-amplified STR loci using a custom designed STR genome reference. Evaluation of this approach demonstrated that the 13 CODIS STR loci and amelogenin (AMEL) locus could be accurately called from individual and mixture samples. Sensitivity analysis showed that as few as 18,500 reads, aligned to an in silico referenced genome, were required to genotype an individual (>99% confidence) for the CODIS loci. The power of this technology was further demonstrated by identification of variant alleles containing single nucleotide polymorphisms (SNPs) and the development of quantitative measurements (reads) for resolving mixed samples. PMID:25621315

Observations from the High Resolution Imaging Science Experiment (HiRISE): Martian dust devils in Gusev and Russell craters

NASA Astrophysics Data System (ADS)

Verba, Circe A.; Geissler, Paul E.; Titus, Timothy N.; Waller, Devin

2010-09-01

Two areas targeted for repeated imaging by detailed High Resolution Imaging Science Experiment (HiRISE) observations allow us to examine morphological differences and monitor seasonal variations of Martian dust devil tracks at two quite different locations. Russell crater (53.3°S, 12.9°E) is regularly imaged to study seasonal processes including deposition and sublimation of CO2 frost. Gusev crater (14.6°S, 175.4°E) has been frequently imaged in support of the Mars Exploration Rover mission. Gusev crater provides the first opportunity to compare “ground truth” orbital observations of dust devil tracks to surface observations of active dust plumes. Orbital observations show that dust devil tracks are rare, forming at a rate <1/110 that of the occurrence of active dust plumes estimated from Spirit's surface observations. Furthermore, the tracks observed from orbit are wider than typical plume diameters observed by Spirit. We conclude that the tracks in Gusev are primarily formed by rare, large dust devils. Smaller dust devils fail to leave tracks that are visible from orbit, perhaps because of limited surface excavation depths. Russell crater displays more frequent, smaller sinuous tracks than Gusev. This may be due to the thin dust cover in Russell, allowing smaller dust devils to penetrate through the bright dust layer and leave conspicuous tracks. The start of the dust devil season and peak activity are delayed in Russell in comparison to Gusev, likely because of its more southerly location. Dust devils in both sites travel in directions consistent with general circulation model (GCM)-predicted winds, confirming a laboratory-derived approach to determining dust devil travel directions based on track morphology.

Dust Devil Tracks

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 8 May 2002) The Science This image, centered near 50.0 S and 17.7 W displays dust devil tracks on the surface. Most of the lighter portions of the image likely have a thin veneer of dust settled on the surface. As a dust devil passes over the surface, it acts as a vacuum and picks up the dust, leaving the darker substrate exposed. In this image there is a general trend of many of the tracks running from east to west or west to east, indicating the general wind direction. There is often no general trend present in dust devil tracks seen in other images. The track patterns are quite ephemeral and can completely change or even disappear over the course of a few months. Dust devils are one of the mechanisms that Mars uses to constantly pump dust into the ubiquitously dusty atmosphere. This atmospheric dust is one of the main driving forces of the present Martian climate. The Story Vrrrrooooooooom. Think of a tornado, the cartoon Tasmanian devil, or any number of vacuum commercials that powerfully suck up swirls of dust and dirt. That's pretty much what it's like on the surface of Mars a lot of the time. Whirlpools of wind called

Automated determination of dust particles trajectories in the coma of comet 67P

NASA Astrophysics Data System (ADS)

Marín-Yaseli de la Parra, J.; Küppers, M.; Perez Lopez, F.; Besse, S.; Moissl, R.

2017-09-01

During more than two years Rosetta spent at comet 67P, it took thousands of images that contain individual dust particles. To arrive at a statistics of the dust properties, automatic image analysis is required. We present a new methodology for fast-dust identification using a star mask reference system for matching a set of images automatically. The main goal is to derive particle size distributions and to determine if traces of the size distribution of primordial pebbles are still present in today's cometary dust [1].

Mars Global Surveyor MOC Images

NASA Technical Reports Server (NTRS)

1999-01-01

Images of several dust devils were captured by the Mars Orbiter Camera (MOC) during its global geodesy campaign. The images shown were taken two days apart, May 13, 1999 and May 15, 1999. Dust devils are columnar vortices of wind that move across the landscape and pick up dust. They look like mini tornadoes.

Dust over Japan

NASA Image and Video Library

2017-12-08

March 24, 2010 - Dust over Japan This image of gray/brown dust being blown over Japan was captured on March 21, 2010 by the MODIS on the Terra satellite. On the left is the Korean peninsula. Japan stretches diagonally across the image, up to the top right corner. The dust is likely from the sandstorm that swept across the China the previous day. The sand and dust originated from the south and east of Inner Mongolia. In this image from March 20, the dust is nearly obscuring the Bohai Sea, which is just west of the Korean peninsula. Here is a handy map. For more information related to this image go to: modis.gsfc.nasa.gov/gallery/individual.php?db_date=2010-0... For more information about Goddard Space Flight Center go here: www.nasa.gov/centers/goddard/home/index.html

Image charge effects on electron capture by dust grains in dusty plasmas.

PubMed

Jung, Y D; Tawara, H

2001-07-01

Electron-capture processes by negatively charged dust grains from hydrogenic ions in dusty plasmas are investigated in accordance with the classical Bohr-Lindhard model. The attractive interaction between the electron in a hydrogenic ion and its own image charge inside the dust grain is included to obtain the total interaction energy between the electron and the dust grain. The electron-capture radius is determined by the total interaction energy and the kinetic energy of the released electron in the frame of the projectile dust grain. The classical straight-line trajectory approximation is applied to the motion of the ion in order to visualize the electron-capture cross section as a function of the impact parameter, kinetic energy of the projectile ion, and dust charge. It is found that the image charge inside the dust grain plays a significant role in the electron-capture process near the surface of the dust grain. The electron-capture cross section is found to be quite sensitive to the collision energy and dust charge.

Impact of Staphylococcus aureus regulatory mutations that modulate biofilm formation in the USA300 strain LAC on virulence in a murine bacteremia model

PubMed Central

Rom, Joseph S.; Atwood, Danielle N.; Beenken, Karen E.; Meeker, Daniel G.; Loughran, Allister J.; Spencer, Horace J.; Lantz, Tamara L.; Smeltzer, Mark S.

2017-01-01

ABSTRACT Staphylococcus aureus causes acute and chronic forms of infection, the latter often associated with formation of a biofilm. It has previously been demonstrated that mutation of atl, codY, rot, sarA, and sigB limits biofilm formation in the USA300 strain LAC while mutation of agr, fur, and mgrA has the opposite effect. Here we used a murine sepsis model to assess the impact of these same loci in acute infection. Mutation of agr, atl, and fur had no impact on virulence, while mutation of mgrA and rot increased virulence. In contrast, mutation of codY, sarA, and sigB significantly attenuated virulence. Mutation of sigB resulted in reduced accumulation of AgrA and SarA, while mutation of sarA resulted in reduced accumulation of AgrA, but this cannot account for the reduced virulence of sarA or sigB mutants because the isogenic agr mutant was not attenuated. Indeed, as assessed by accumulation of alpha toxin and protein A, all of the mutants we examined exhibited unique phenotypes by comparison to an agr mutant and to each other. Attenuation of the sarA, sigB and codY mutants was correlated with increased production of extracellular proteases and global changes in extracellular protein profiles. These results suggest that the inability to repress the production of extracellular proteases plays a key role in attenuating the virulence of S. aureus in acute as well as chronic, biofilm-associated infections, thus opening up the possibility that strategies aimed at the de-repression of protease production could be used to broad therapeutic advantage. They also suggest that the impact of codY, sarA, and sigB on protease production occurs via an agr-independent mechanism. PMID:28910576

Cost-effectiveness of a European ST-segment elevation myocardial infarction network: results from the Catalan Codi Infart network

PubMed Central

Bosch, Julia; Martín-Yuste, Victoria; Rosas, Alba; Faixedas, Maria Teresa; Gómez-Hospital, Joan Antoni; Figueras, Jaume; Curós, Antoni; Cequier, Angel; Goicolea, Javier; Fernández-Ortiz, Antonio; Macaya, Carlos; Tresserras, Ricard; Pellisé, Laura; Sabaté, Manel

2015-01-01

Objectives To evaluate the cost-effectiveness of the ST-segment elevation myocardial infarction (STEMI) network of Catalonia (Codi Infart). Design Cost-utility analysis. Setting The analysis was from the Catalonian Autonomous Community in Spain, with a population of about 7.5 million people. Participants Patients with STEMI treated within the autonomous community of Catalonia (Spain) included in the IAM CAT II-IV and Codi Infart registries. Outcome measures Costs included hospitalisation, procedures and additional personnel and were obtained according to the reperfusion strategy. Clinical outcomes were defined as 30-day avoided mortality and quality-adjusted life-years (QALYs), before (N=356) and after network implementation (N=2140). Results A substitution effect and a technology effect were observed; aggregate costs increased by 2.6%. The substitution effect resulted from increased use of primary coronary angioplasty, a relatively expensive procedure and a decrease in fibrinolysis. Primary coronary angioplasty increased from 31% to 89% with the network, and fibrinolysis decreased from 37% to 3%. Rescue coronary angioplasty declined from 11% to 4%, and no reperfusion from 21% to 4%. The technological effect was related to improvements in the percutaneous coronary intervention procedure that increased efficiency, reducing the average length of the hospital stay. Mean costs per patient decreased from €8306 to €7874 for patients with primary coronary angioplasty. Clinical outcomes in patients treated with primary coronary angioplasty did not change significantly, although 30-day mortality decreased from 7.5% to 5.6%. The incremental cost-effectiveness ratio resulted in an extra cost of €4355 per life saved (30-day mortality) and €495 per QALY. Below a cost threshold of €30 000, results were sensitive to variations in costs and outcomes. Conclusions The Catalan STEMI network (Codi Infart) is cost-efficient. Further studies are needed in geopolitical different scenarios. PMID:26656019

A simplified Suomi NPP VIIRS dust detection algorithm

NASA Astrophysics Data System (ADS)

Yang, Yikun; Sun, Lin; Zhu, Jinshan; Wei, Jing; Su, Qinghua; Sun, Wenxiao; Liu, Fangwei; Shu, Meiyan

2017-11-01

Due to the complex characteristics of dust and sparse ground-based monitoring stations, dust monitoring is facing severe challenges, especially in dust storm-prone areas. Aim at constructing a high-precision dust storm detection model, a pixel database, consisted of dusts over a variety of typical feature types such as cloud, vegetation, Gobi and ice/snow, was constructed, and their distributions of reflectance and Brightness Temperatures (BT) were analysed, based on which, a new Simplified Dust Detection Algorithm (SDDA) for the Suomi National Polar-Orbiting Partnership Visible infrared Imaging Radiometer (NPP VIIRS) is proposed. NPP VIIRS images covering the northern China and Mongolian regions, where features serious dust storms, were selected to perform the dust detection experiments. The monitoring results were compared with the true colour composite images, and results showed that most of the dust areas can be accurately detected, except for fragmented thin dusts over bright surfaces. The dust ground-based measurements obtained from the Meteorological Information Comprehensive Analysis and Process System (MICAPS) and the Ozone Monitoring Instrument Aerosol Index (OMI AI) products were selected for comparison purposes. Results showed that the dust monitoring results agreed well in the spatial distribution with OMI AI dust products and the MICAPS ground-measured data with an average high accuracy of 83.10%. The SDDA is relatively robust and can realize automatic monitoring for dust storms.

MISR Browse Images: Puerto Rico Dust Experiment (PRiDE)

Atmospheric Science Data Center

2013-04-02

MISR Browse Images: Puerto Rico Dust Experiment (PRiDE) These MISR Browse ... a quick visual overview of the region observed during the Puerto Rico Dust Experiment (PRiDE) field campaign. PRiDE was a study of the ...

The Two-faced Whirlpool Galaxy

NASA Image and Video Library

2017-12-08

NASA image release January 13, 2011 These images by NASA's Hubble Space Telescope show off two dramatically different face-on views of the spiral galaxy M51, dubbed the Whirlpool Galaxy. The image here, taken in visible light, highlights the attributes of a typical spiral galaxy, including graceful, curving arms, pink star-forming regions, and brilliant blue strands of star clusters. In the image above, most of the starlight has been removed, revealing the Whirlpool's skeletal dust structure, as seen in near-infrared light. This new image is the sharpest view of the dense dust in M51. The narrow lanes of dust revealed by Hubble reflect the galaxy's moniker, the Whirlpool Galaxy, as if they were swirling toward the galaxy's core. To map the galaxy's dust structure, researchers collected the galaxy's starlight by combining images taken in visible and near-infrared light. The visible-light image captured only some of the light; the rest was obscured by dust. The near-infrared view, however, revealed more starlight because near-infrared light penetrates dust. The researchers then subtracted the total amount of starlight from both images to see the galaxy's dust structure. The red color in the near-infrared image traces the dust, which is punctuated by hundreds of tiny clumps of stars, each about 65 light-years wide. These stars have never been seen before. The star clusters cannot be seen in visible light because dense dust enshrouds them. The image reveals details as small as 35 light-years across. Astronomers expected to see large dust clouds, ranging from about 100 light-years to more than 300 light-years wide. Instead, most of the dust is tied up in smooth and diffuse dust lanes. An encounter with another galaxy may have prevented giant clouds from forming. Probing a galaxy's dust structure serves as an important diagnostic tool for astronomers, providing invaluable information on how the gas and dust collapse to form stars. Although Hubble is providing incisive views of the internal structure of galaxies such as M51, the planned James Webb Space Telescope (JWST) is expected to produce even crisper images. Researchers constructed the image by combining visible-light exposures from Jan. 18 to 22, 2005, with the Advanced Camera for Surveys (ACS), and near-infrared light pictures taken in December 2005 with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook Credit: NASA, ESA, M. Regan and B. Whitmore (STScI), and R. Chandar (University of Toledo)

The Two-faced Whirlpool Galaxy

NASA Image and Video Library

2011-01-13

NASA image release January 13, 2011 These images by NASA's Hubble Space Telescope show off two dramatically different face-on views of the spiral galaxy M51, dubbed the Whirlpool Galaxy. The image above, taken in visible light, highlights the attributes of a typical spiral galaxy, including graceful, curving arms, pink star-forming regions, and brilliant blue strands of star clusters. In the image here, most of the starlight has been removed, revealing the Whirlpool's skeletal dust structure, as seen in near-infrared light. This new image is the sharpest view of the dense dust in M51. The narrow lanes of dust revealed by Hubble reflect the galaxy's moniker, the Whirlpool Galaxy, as if they were swirling toward the galaxy's core. To map the galaxy's dust structure, researchers collected the galaxy's starlight by combining images taken in visible and near-infrared light. The visible-light image captured only some of the light; the rest was obscured by dust. The near-infrared view, however, revealed more starlight because near-infrared light penetrates dust. The researchers then subtracted the total amount of starlight from both images to see the galaxy's dust structure. The red color in the near-infrared image traces the dust, which is punctuated by hundreds of tiny clumps of stars, each about 65 light-years wide. These stars have never been seen before. The star clusters cannot be seen in visible light because dense dust enshrouds them. The image reveals details as small as 35 light-years across. Astronomers expected to see large dust clouds, ranging from about 100 light-years to more than 300 light-years wide. Instead, most of the dust is tied up in smooth and diffuse dust lanes. An encounter with another galaxy may have prevented giant clouds from forming. Probing a galaxy's dust structure serves as an important diagnostic tool for astronomers, providing invaluable information on how the gas and dust collapse to form stars. Although Hubble is providing incisive views of the internal structure of galaxies such as M51, the planned James Webb Space Telescope (JWST) is expected to produce even crisper images. Researchers constructed the image by combining visible-light exposures from Jan. 18 to 22, 2005, with the Advanced Camera for Surveys (ACS), and near-infrared light pictures taken in December 2005 with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). Credit: NASA, ESA, S. Beckwith (STScI), and the Hubble Heritage Team (STScI/AURA) The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

Results from Automated Cloud and Dust Devil Detection Onboard the MER

NASA Technical Reports Server (NTRS)

Chien, Steve; Castano, Rebecca; Bornstein, Benjamin; Fukunaga, Alex; Castano, Andres; Biesiadecki, Jeffrey; Greeley, Ron; Whelley, Patrick; Lemmon, Mark

2008-01-01

We describe a new capability to automatically detect dust devils and clouds in imagery onboard rovers, enabling downlink of just the images with the targets or only portions of the images containing the targets. Previously, the MER rovers conducted campaigns to image dust devils and clouds by commanding a set of images be collected at fixed times and downloading the entire image set. By increasing the efficiency of the campaigns, more campaigns can be executed. Software for these new capabilities was developed, tested, integrated, uploaded, and operationally checked out on both rovers as part of the R9.2 software upgrade. In April 2007 on Sol 1147 a dust devil was automatically detected onboard the Spirit rover for the first time. We discuss the operational usage of the capability and present initial dust devil results showing how this preliminary application has demonstrated the feasibility and potential benefits of the approach.

Directional analysis and filtering for dust storm detection in NOAA-AVHRR imagery

NASA Astrophysics Data System (ADS)

Janugani, S.; Jayaram, V.; Cabrera, S. D.; Rosiles, J. G.; Gill, T. E.; Rivera Rivera, N.

2009-05-01

In this paper, we propose spatio-spectral processing techniques for the detection of dust storms and automatically finding its transport direction in 5-band NOAA-AVHRR imagery. Previous methods that use simple band math analysis have produced promising results but have drawbacks in producing consistent results when low signal to noise ratio (SNR) images are used. Moreover, in seeking to automate the dust storm detection, the presence of clouds in the vicinity of the dust storm creates a challenge in being able to distinguish these two types of image texture. This paper not only addresses the detection of the dust storm in the imagery, it also attempts to find the transport direction and the location of the sources of the dust storm. We propose a spatio-spectral processing approach with two components: visualization and automation. Both approaches are based on digital image processing techniques including directional analysis and filtering. The visualization technique is intended to enhance the image in order to locate the dust sources. The automation technique is proposed to detect the transport direction of the dust storm. These techniques can be used in a system to provide timely warnings of dust storms or hazard assessments for transportation, aviation, environmental safety, and public health.

Martian Arctic Dust Devil, Phoenix Sol 104

NASA Technical Reports Server (NTRS)

2008-01-01

The Surface Stereo Imager on NASA's Phoenix Mars Lander caught this dust devil in action west-southwest of the lander at 11:16 a.m. local Mars time on Sol 104, or the 104th Martian day of the mission, Sept. 9, 2008.

Dust devils have not been detected in any Phoenix images from earlier in the mission, but at least six were observed in a dozen images taken on Sol 104.

Dust devils are whirlwinds that often occur when the Sun heats the surface of Mars, or some areas on Earth. The warmed surface heats the layer of atmosphere closest to it, and the warm air rises in a whirling motion, stirring dust up from the surface like a miniature tornado.

The dust devil visible in the center of this image just below the horizon is estimated to be about 400 meters (about 1,300 feet) from Phoenix, and 4 meters (13 feet) in diameter. It is much smaller than dust devils that have been observed by NASA's Mars Exploration Rover Spirit much closer to the equator. It is closer in size to dust devils seen from orbit in the Phoenix landing region, though still smaller than those.

The image has been enhanced to make the dust devil easier to see.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

African Dust Blows over the Caribbean

NASA Technical Reports Server (NTRS)

2002-01-01

Shuttle astronauts frequently track Saharan dust storms as they blow from north Africa across the Atlantic Ocean. Dust palls blowing from Africa take about a week to cross the Atlantic. Recently, researchers have linked Saharan dust to coral disease, allergic reactions in humans, and red tides. The top photograph, a classic image showing African dust over the Caribbean, was taken at a time when few scientists had considered the possibility. The image was taken by Space Shuttle astronauts on July 11, 1994 (STS065-75-47). This photograph looks southwest over the northern edge of a large trans-Atlantic dust plume that blew off the Sahara desert in Africa. In this view, Caicos Island in the Bahamas and the mountainous spines of Haiti are partly obscured by the dust. Closer to the foreground, (about 26 degrees north latitude), the skies are clear. The lower photograph (STS105-723-7) was taken by Space Shuttle astronauts while docked to the International Space Station on August 19, 2001. The spacecraft is over the Atlantic Ocean at roughly 45oN, 60oW. The astronauts were looking obliquely to the south; the boundaries of the dust plumes can be traced visually by the abrupt change from clear to hazy atmosphere-the hazy line marks the northern edge of the dust pall near the Caribbean. Images provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

Use of Satellite and Ground-based Digital Images to Detect and Monitor Dust Storms in the Mojave Desert

NASA Astrophysics Data System (ADS)

Chavez, P. S.; MacKinnon, D. J.; Reynolds, R. L.; Velasco, M. G.

2002-12-01

Wind-induced dust emission from sources in the southwestern United States is not a major contributor to global dust flux, but it is important on a regional and national scale because of its effects on air quality, human health and safety, as well as ecosystem dynamics. Integrated remotely sensed satellite, airborne, and ground-based image data have strong potential to detect and monitor active dust storms and map areas vulnerable to wind erosion in the Southwest. Since 1999, high temporal resolution digital images collected by satellite and a ground-based, automated digital camera station have been used to detect, monitor, and analyze the location, size, frequency, duration, and transport patterns of large dust storms in the central Mojave Desert. One of the biggest dust storms of this past decade occurred on April 15, 2002, when at least several million metric tons of dust were emitted from the central Mojave Desert alone. During this storm, geostationary satellite (GOES) images documented the arrival of two very large dust plumes into the Las Vegas Valley, NV, one from a valley about 40 km to the west and the other from a heavily used area about 170 km to the southwest. Large, rapid increases in levels of PM10 (particulate matter less than 10 micrometers) in the Las Vegas area corresponded with the arrival of these plumes, with PM10 values increasing from a range of approximately 100 to 250 micrograms/m3 to 1,100 to 1,500 micrograms/m3 within 30 minutes. Satellite imaging systems currently available cannot detect and monitor dust storms of the size typically generated in the Southwest on an operational basis or be used to produce models for emission-rate predictions. The satellite imaging system on GOES is the only one available having adequate temporal resolution to detect and monitor active dust storms on a routine basis; however, it can only detect very large dust storms because its spatial and spectral resolutions are very low. A satellite imaging system with three to five spectral bands (with adjustable gain settings) and approximately 100 m spatial and 15 to 20 minutes temporal resolutions is needed to effectively monitor southwestern dust storms and events. Such a system would also be useful in other arid regions.

Detecting Exoplanets with the New Worlds Observer: The Problem of Exozodiacal Dust

NASA Technical Reports Server (NTRS)

Roberge, A.; Noecker, M. C.; Glassman, T. M.; Oakley, P.; Turnbull, M. C.

2009-01-01

Dust coming from asteroids and comets will strongly affect direct imaging and characterization of terrestrial planets in the Habitable Zones of nearby stars. Such dust in the Solar System is called the zodiacal dust (or 'zodi' for short). Higher levels of similar dust are seen around many nearby stars, confined in disks called debris disks. Future high-contrast images of an Earth-like exoplanet will very likely be background-limited by light scattered of both the local Solar System zodi and the circumstellar dust in the extrasolar system (the exozodiacal dust). Clumps in the exozodiacal dust, which are expected in planet-hosting systems, may also be a source of confusion. Here we discuss the problems associated with imaging an Earth-like planet in the presence of unknown levels of exozodiacal dust. Basic formulae for the exoplanet imaging exposure time as function of star, exoplanet, zodi, exozodi, and telescope parameters will be presented. To examine the behavior of these formulae, we apply them to the New Worlds Observer (NWO) mission. NWO is a proposed 4-meter UV/optical/near-IR telescope, with a free flying starshade to suppress the light from a nearby star and achieve the high contrast needed for detection and characterization of a terrestrial planet in the star's Habitable Zone. We find that NWO can accomplish its science goals even if exozodiacal dust levels are typically much higher than the Solar System zodi level. Finally, we highlight a few additional problems relating to exozodiacal dust that have yet to be solved.

36 CFR 200.2 - Field organization.

Code of Federal Regulations, 2011 CFR

2011-07-01

...): Colorado Arapaho-Roosevelt Fort Collins. Grand Mesa-Uncompahgre and Gunnison Delta. Pike-San Isabel Pueblo... Cody. Region 3, Southwestern Region (Regional Forester, Federal Bldg., 517 Gold Ave. SW., Albuquerque...

36 CFR 200.2 - Field organization.

Code of Federal Regulations, 2014 CFR

2014-07-01

...): Colorado Arapaho-Roosevelt Fort Collins. Grand Mesa-Uncompahgre and Gunnison Delta. Pike-San Isabel Pueblo... Cody. Region 3, Southwestern Region (Regional Forester, Federal Bldg., 517 Gold Ave. SW., Albuquerque...

36 CFR 200.2 - Field organization.

Code of Federal Regulations, 2013 CFR

2013-07-01

...): Colorado Arapaho-Roosevelt Fort Collins. Grand Mesa-Uncompahgre and Gunnison Delta. Pike-San Isabel Pueblo... Cody. Region 3, Southwestern Region (Regional Forester, Federal Bldg., 517 Gold Ave. SW., Albuquerque...

36 CFR 200.2 - Field organization.

Code of Federal Regulations, 2012 CFR

2012-07-01

...): Colorado Arapaho-Roosevelt Fort Collins. Grand Mesa-Uncompahgre and Gunnison Delta. Pike-San Isabel Pueblo... Cody. Region 3, Southwestern Region (Regional Forester, Federal Bldg., 517 Gold Ave. SW., Albuquerque...

Dust storm in the Gobi Desert, China

NASA Image and Video Library

2017-12-08

On March 8, 2013 dust plumes rose from the Gobi Desert and blew along the China-Mongolia border. Strong winds kept the dust aloft for several days, and dust appeared as far eastward as Henan Province and as far south as the Sichuan Basin by March 13. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this true-color image on March 9. The dust had continued traveling toward the southeast, and the camel-colored plume extended several hundred kilometers into eastern China. In the southeast (lower right corner of this image), the dust approached China’s coastal plain. Gray haze hung over that region and although the dust likely worsened air quality there, the gray color of the haze suggested other sources, such as urban and industrial smog, and smoke from fires. At least one fire sent a discernible smoke plume eastward, ahead of the dust. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Overview of the magnetic properties experiments on the Mars Exploration Rovers

NASA Astrophysics Data System (ADS)

Madsen, M. B.; Goetz, W.; Bertelsen, P.; Binau, C. S.; Folkmann, F.; Gunnlaugsson, H. P.; Hjøllum, J.; Hviid, S. F.; Jensen, J.; Kinch, K. M.; Leer, K.; Madsen, D. E.; Merrison, J.; Olsen, M.; Arneson, H. M.; Bell, J. F.; Gellert, R.; Herkenhoff, K. E.; Johnson, J. R.; Johnson, M. J.; Klingelhöfer, G.; McCartney, E.; Ming, D. W.; Morris, R. V.; Proton, J. B.; Rodionov, D.; Sims, M.; Squyres, S. W.; Wdowiak, T.; Yen, A. S.

2009-06-01

The Mars Exploration Rovers have accumulated airborne dust on different types of permanent magnets. Images of these magnets document the dynamics of dust capture and removal over time. The strongly magnetic subset of airborne dust appears dark brown to black in Panoramic Camera (Pancam) images, while the weakly magnetic one is bright red. Images returned by the Microscopic Imager reveal the formation of magnetic chains diagnostic of magnetite-rich grains with substantial magnetization (>8 Am2 kg-1). On the basis of Mössbauer spectra the dust contains magnetite, olivine, pyroxene, and nanophase oxides in varying proportions, depending on wind regime and landing site. The dust contains a larger amount of ferric iron (Fe3+/Fetot ˜ 0.6) than rocks in the Gusev plains (˜0.1-0.2) or average Gusev soil (˜0.3). Alpha Particle X-Ray Spectrometer data of the dust show that some of the iron in magnetite is substituted by titanium and chromium. The good correlation of the amount of calcium and sulfur in the dust may be caused by the presence of a calcium sulfate related phase. The overall mineralogical composition points to a basaltic origin of the airborne dust, although some alteration has taken place as indicated by the large degree of oxidation.

Overview of the magnetic properties experiments on the Mars Exploration Rovers

USGS Publications Warehouse

Madsen, M.B.; Goetz, W.; Bertelsen, P.; Binau, C.S.; Folkmann, F.; Gunnlaugsson, H.P.; Hjollum, J.I.; Hviid, S.F.; Jensen, J.; Kinch, K.M.; Leer, K.; Madsen, D.E.; Merrison, J.; Olsen, M.; Arneson, H.M.; Bell, J.F.; Gellert, Ralf; Herkenhoff, K. E.; Johnson, J. R.; Johnson, M.J.; Klingelhofer, G.; McCartney, E.; Ming, D. W.; Morris, R.V.; Proton, J.B.; Rodionov, D.; Sims, M.; Squyres, S. W.; Wdowiak, T.; Yen, A. S.

2009-01-01

The Mars Exploration Rovers have accumulated airborne dust on different types of permanent magnets. Images of these magnets document the dynamics of dust capture and removal over time. The strongly magnetic subset of airborne dust appears dark brown to black in Panoramic Camera (Pancam) images, while the weakly magnetic one is bright red. Images returned by the Microscopic Imager reveal the formation of magnetic chains diagnostic of magnetite-rich grains with substantial magnetization (>8 Am2 kg-1). On the basis of M??ssbauer spectra the dust contains magnetite, olivine, pyroxene, and nanophase oxides in varying proportions, depending on wind regime and landing site. The dust contains a larger amount of ferric iron (Fe3+/Fe tot ??? 0.6) than rocks in the Gusev plains (???0.1-0.2) or average Gusev soil (???0.3). Alpha Particle X-Ray Spectrometer data of the dust show that some of the iron in magnetite is substituted by titanium and chromium. The good correlation of the amount of calcium and sulfur in the dust may be caused by the presence of a calcium sulfate related phase. The overall mineralogical composition points to a basaltic origin of the airborne dust, although some alteration has taken place as indicated by the large degree of oxidation. Copyright 2009 by the American Geophysical Union.

Use of dust storm observations on satellite images to identify areas vulnerable to severe wind erosion

USGS Publications Warehouse

Breed, C.S.; McCauley, J.F.

1986-01-01

Blowing dust is symptomatic of severe wind erosion and deterioration of soils in areas undergoing dessication and/or devegetation. Dust plumes on satellite images can commonly be traced to sources in marginally arable semiarid areas where protective lag gravels or vegetation have been removed and soils are dry, as demonstrated for the Portales Valley, New Mexico. Images from Landsat and manned orbiters such as Skylab and the Space Shuttle are useful for illustrating the regional relations of airborne dust plumes to source areas. Geostationary satellites such as GOES are useful in tracking the time-histories of episodic dust storms. These events sometimes go unrecognized by weather observers and are the precursors of long-term land degradation trends. In areas where soil maps and meteorological data are inadequate, satellite images provide a means for identifying problem areas where measures are needed to control or mitigate wind erosion. ?? 1986 D. Reidel Publishing Company.

NGC 7538 IRS. 1. Interaction of a Polarized Dust Spiral and a Molecular Outflow

NASA Astrophysics Data System (ADS)

Wright, M. C. H.; Hull, Charles L. H.; Pillai, Thushara; Zhao, Jun-Hui; Sandell, Göran

2014-12-01

We present dust polarization and CO molecular line images of NGC 7538 IRS 1. We combined data from the Submillimeter Array, the Combined Array for Research in Millimeter-wave Astronomy, and the James Clerk Maxwell Telescope to make images with ~2.''5 resolution at 230 and 345 GHz. The images show a remarkable spiral pattern in both the dust polarization and molecular outflow. These data dramatically illustrate the interplay between a high infall rate onto IRS 1 and a powerful outflow disrupting the dense, clumpy medium surrounding the star. The images of the dust polarization and the CO outflow presented here provide observational evidence for the exchange of energy and angular momentum between the infall and the outflow. The spiral dust pattern, which rotates through over 180° from IRS 1, may be a clumpy filament wound up by conservation of angular momentum in the infalling material. The redshifted CO emission ridge traces the dust spiral closely through the MM dust cores, several of which may contain protostars. We propose that the CO maps the boundary layer where the outflow is ablating gas from the dense gas in the spiral.

Saharan Dust on the Move

NASA Image and Video Library

2017-12-08

A piece of Africa—actually lots of them—began to arrive in the Americas in June 2014. On June 23, a lengthy river of dust from western Africa began to push across the Atlantic Ocean on easterly winds. A week later, the influx of dust was affecting air quality as far away as the southeastern United States. This composite image, made with data from the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP, shows dust heading west toward South America and the Gulf of Mexico on June 25, 2014. The dust flowed roughly parallel to a line of clouds in the intertropical convergence zone, an area near the equator where the trade winds come together and rain and clouds are common. In imagery captured by the Moderate Resolution Imaging Spectroradiometer (MODIS), the dust appeared to be streaming from Mauritania, Senegal, and Western Sahara, though some of it may have originated in countries farther to the east. Saharan dust has a range of impacts on ecosystems downwind. Each year, dust events like the one pictured here deliver about 40 million tons of dust from the Sahara to the Amazon River Basin. The minerals in the dust replenish nutrients in rainforest soils, which are continually depleted by drenching, tropical rains. Research focused on peat soils in the Everglades show that African dust has been arriving regularly in South Florida for thousands of years as well. In some instances, the impacts are harmful. Infusion of Saharan dust, for instance, can have a negative impact on air quality in the Americas. And scientists have linked African dust to outbreaks of certain types of toxic algal blooms in the Gulf of Mexico and southern Florida. Read more: 1.usa.gov/1snkzmS NASA images by Norman Kuring, NASA’s Ocean Color web. Caption by Adam Voiland. Credit: NASA Earth Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Trace Elemental Characterization of Chalk Dust and Their Associated Health Risk Assessment.

PubMed

Maruthi, Y A; Ramprasad, S; Lakshmana Das, N

2017-02-01

It is evident that chalk produces dust on use, i.e., particulate matter, which will alter the air quality of classrooms and can cause health hazards in teachers. The possible causes for health effects of chalk dust on teachers are still unclear. Hence, the aim of this study is to estimate the concentration of trace elements (Al, Cr, Mn, Fe, Co, Ni, Si, Pb) in chalk dust collected from classrooms by using ICP-MS. Both suspended and settled chalk dust was collected from selected classrooms. Suspended chalk dust was collected with PM2.5 filter paper using fine dust sampler, and settled chalk dust was collected by placing petriplates at a distance of 3 m from the board for a duration period of 30 min. Scanning electron microscopy images of chalk dust were taken up. Potential health risk analysis was also assessed. Results showed that Al, Fe, and Mn are in higher concentration (>1000 μg kg -1 ) in both settled and suspended chalk dust. Cr, Mn, Fe, Co, and Ni were beyond the minimal risk levels in both settled and suspended chalk dust. There are no minimal risk levels for the elements Al, Si, and Pb. The concentration of trace elements in suspended chalk dust was higher than that in settled chalk dust. The SEM images of PM2.5 filter papers (suspended chalk dust) showed that all pores of the sampled filter papers are clogged with chalk dust. The few SEM images of the settled chalk dust showed fibrous shape which is associated with good-quality chalk whereas others showed circular and more aggregated nature of chalk dust from low-quality chalk from which the dust production will be very high. As observed from the result that the trace elements concentration was high in the suspended chalk dust, the fact can be correlated with the SEM images which have shown high density of absorbed chalk dust. With reference to human health risk, dermal exposure was the main route of exposure followed by inhalation and ingestion. Al (aluminum), Fe (iron), Si (silicon), and Mn (manganese) are the major contributors for the non-carcinogenic effects. For all the elements, the carcinogenic effect calculated (LADD) is within the global acceptable limit (10 -6 -10 -4 ).

Dust Devils in Gusev Crater, Sol 463

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows a several dust devils -- whirlwinds that loft dust into the air -- moving across a plain below the hillside vantage point of NASA's Mars Exploration Rover Spirit. Several of the dust devils are visible at once in some of the frames in this sequence. The local solar time was about 2 p.m., when the ground temperature was high enough to cause turbulence that kicks up dust devils as the wind blows across the plain. The number of seconds elapsed since the first frame is indicated at lower left of the images, typically 20 seconds between frames. Spirit's navigation camera took these images on the rover's 463rd martian day, or sol (April 22, 2005.) Contrast has been enhanced for anything in the images that changes from frame to frame, that is, for the dust devil.

Scientists expected dust devils since before Spirit landed. The landing area inside Gusev Crater is filled with dark streaks left behind when dust devils pick dust up from an area. It is also filled with bright 'hollows,' which are dust-filled miniature craters. Dust covers most of the terrain. Winds flow into and out of Gusev crater every day. The Sun heats the surface so that the surface is warm to the touch even though the atmosphere at 2 meters (6 feet) above the surface would be chilly. That temperature contrast causes convection. Mixing the dust, winds, and convection can trigger dust devils.

Several Dust Devils in Gusev Crater, Sol 461

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows a several dust devils -- whirlwinds that loft dust into the air -- moving across a plain below the hillside vantage point of NASA's Mars Exploration Rover Spirit. Several of the dust devils are visible at once in some of the 21 frames in this sequence. The local solar time was about 2 p.m., when the ground temperature was high enough to cause turbulence that kicks up dust devils as the wind blows across the plain. The number of seconds elapsed since the first frame is indicated at lower left of the images, typically 20 seconds between frames. Spirit's navigation camera took these images on the rover's 461st martian day, or sol (April 20, 2005.) Contrast has been enhanced for anything in the images that changes from frame to frame, that is, for the dust devil.

Scientists expected dust devils since before Spirit landed. The landing area inside Gusev Crater is filled with dark streaks left behind when dust devils pick dust up from an area. It is also filled with bright 'hollows,' which are dust-filled miniature craters. Dust covers most of the terrain. Winds flow into and out of Gusev crater every day. The Sun heats the surface so that the surface is warm to the touch even though the atmosphere at 2 meters (6 feet) above the surface would be chilly. That temperature contrast causes convection. Mixing the dust, winds, and convection can trigger dust devils.

Sunset over Ares Vallis

NASA Technical Reports Server (NTRS)

1997-01-01

Every several days, Mars Pathfinder will image the sunrise and sunset on Mars. Future images will show a larger area -- we have a higher data rate than we expected when we planned this image, so we can get more information. Images taken at sunset, like this, and up to two hours later, will be used to investigate the distribution of dust within the Martian atmosphere. Already, we can see some dust layers in the images. By seeing how the twilight fades with time -- it lasts for over two hours -- we can determine that the dust extends high into the atmosphere.

Mapping the Spatial Distribution of Dust Extinction in NGC 959 Using Broadband Visible and Mid-Infrared Filters

NASA Astrophysics Data System (ADS)

Tamura, K.; Jansen, R. A.; Windhorst, R. A.

2009-12-01

We present a method to estimate and map the two-dimensional distribution of dust extinction in the late-type spiral galaxy NGC 959 from the theoretical and observed flux ratio of optical V and mid-IR (MIR) 3.6 μm images. Our method is applicable to both young and old stellar populations for a range of metallicities, and is not restricted to lines of sight toward star-formation (SF) regions. We explore this method using a pixel-based analysis on images of NGC 959 obtained in the V band at the Vatican Advanced Technology Telescope and at 3.6 μm (L band) with Spitzer/Infrared Array Camera. We present the original and extinction corrected Galaxy Evolution Explorer (GALEX) far-UV (FUV) and near-UV (NUV) images, as well as optical UBVR images of NGC 959. While the dust lanes are not clearly evident at GALEX resolution, our dust map clearly traces the dust that can be seen silhouetted against the galaxy's disk in the high-resolution Hubble Space Telescope (HST) images of NGC 959. The advantages of our method are (1) it only depends on two relatively common broadband images in the optical V band and in the MIR at 3.6 μm (but adding a near-UV band improves its fidelity); and (2) it is able to map the two-dimensional spatial distribution of dust within a galaxy. This powerful tool could be used to measure the detailed distribution of dust extinction within higher redshift galaxies to be observed with, e.g., the Hubble Space Telescope (HST)/WFC3 (optical near-IR) and James Webb Space Telescope (mid-IR), and to distinguish properties of dust within galaxy bulges, spiral arms, and inter-arm regions.

Characterisation of mineral dust emission in the Middle EAST using the Spinning Enhanced Visible and Infrared Imager (SEVIRI)

NASA Astrophysics Data System (ADS)

Hennen, M.; Shahgedanova, M.; White, K.

2015-12-01

Using the Spinning Enhanced Visual and InfraRed Imager (SEVIRI) on-board Meteosat's second generation satellite (MSG), mineral dust emissions from the Middle East were observed at a high temporal and spatial resolution between the years 2006 and 2013. This research provides a subjective derivation of mineral dust source locations in the Middle East using the thermal infrared Dust RGB product. Focusing on the brightness temperature difference around 10.8 µm channel and their spectral contrast with clear sky conditions, the Dust RGB product has been recognised as a major asset in detecting dust. While the product has already been used to map dust emissions in Sahara and south Africa, this research is the first to map dust emissions in the Middle East using SEVIRI, one of the dustiest regions in the world second only to the Sahara Desert. For every dust storm activation within the Middle East, the point of first emission is derived from visual inspection of each 15 minute image, these points were then recorded in a dust source climatology (DSC) database, along with time and direction of dust movement. To take account of potential errors inherent in this subjective detection method, a degree of confidence is associated with each data point with relevance to time of day (which has a strong effect on ability to detect dust in these products) and weather conditions, in particular presence of clouds. These results are compared with an automated retrieval using Aerosol Optical Depth (AOD) measurements form the Moderate Resolution Image Spectrometer (MODIS); which, due to its sun-synchronous orbit allows a measurement of dust in the atmosphere once a day. Differences in the spatial distribution of SEVIRI dust sources and MODIS inferred dust source regions can be explained by inherent transport bias in the latter's low sampling rate and prevailing wind conditions. This database will provide an important tool in further understanding dust emission processes in the region, laying the foundations for future studies relating to climatic conditions, especially droughts, and changes in land cover.

Martian Arctic Dust Devil and Phoenix Meteorology Mast

NASA Technical Reports Server (NTRS)

2008-01-01

The Surface Stereo Imager on NASA's Phoenix Mars Lander caught this dust devil in action west-southwest of the lander at 11:16 a.m. local Mars time on Sol 104, or the 104th Martian day of the mission, Sept. 9, 2008.

Dust devils have not been detected in any Phoenix images from earlier in the mission, but at least six were observed in a dozen images taken on Sol 104.

Dust devils are whirlwinds that often occur when the Sun heats the surface of Mars, or some areas on Earth. The warmed surface heats the layer of atmosphere closest to it, and the warm air rises in a whirling motion, stirring dust up from the surface like a miniature tornado.

The vertical post near the left edge of this image is the mast of the Meteorological Station on Phoenix. The dust devil visible at the horizon just to the right of the mast is estimated to be 600 to 700 meters (about 2,000 to 2,300 feet) from Phoenix, and 4 to 5 meters (10 to 13 feet) in diameter. It is much smaller than dust devils that have been observed by NASA's Mars Exploration Rover Spirit much closer to the equator. It is closer in size to dust devils seen from orbit in the Phoenix landing region, though still smaller than those.

The image has been enhanced to make the dust devil easier to see.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

An Investigation of Dust Storms Observed with the Mars Color Imager

NASA Technical Reports Server (NTRS)

Guzewich, Scott D.; Toigo, Anthony D.; Wang, Huiqun

2017-01-01

Daily global imaging by the Mars Color Imager (MARCI) continues the record of the Mars Orbiter Camera (MOC) and has allowed creation of a long-duration record of Martian dust storms. We observe dust storms over the first two Mars years of the MARCI record, including tracking individual storms over multiple sols, as well as tracking the growth and recession of the seasonal polar caps. Using the combined 6 Mars year record of textured dust storms (storms with visible textures on the observed dust cloud tops), we study the relationship between textured dust storm activity and meteorology (as simulated by the MarsWRF general circulation model) and surface properties. We find that textured dust storms preferentially occur in places and seasons with above average surface wind stress. Textured dust storm occurrence also has a modest linear anti-correlation with surface albedo (0.43) and topography (0.40). Lastly, we perform an empirical orthogonal function (EOF) analysis on the distribution of occurrence of textured dust storms and find that over 50 of the variance in textured dust storm activity can be explained by two EOF modes. We associate the first EOF mode with cap-edge storms just before Ls = 180deg and the second EOF mode with flushing dust storms that occur from Ls = 180-210deg and again near Ls = 320deg.

Extracting lunar dust parameters from image charge signals produced by the Lunar Dust Experiment

NASA Astrophysics Data System (ADS)

Stanley, J.; Kempf, S.; Horanyi, M.; Szalay, J.

2015-12-01

The Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) is an impact ionization dust detector used to characterize the lunar dust exosphere generated by the impacts of large interplanetary particles and meteor streams (Horanyi et al., 2015). In addition to the mass and speed of these lofted particles, LDEX is sensitive to their charge. The resulting signatures of impact events therefore provide valuable information about not only the ambient plasma environment, but also the speed vectors of these dust grains. Here, impact events produced from LDEX's calibration at the Dust Accelerator Laboratory are analyzed using an image charge model derived from the electrostatic simulation program, Coulomb. We show that parameters such as dust grain speed, size, charge, and position of entry into LDEX can be recovered and applied to data collected during LADEE's seven-month mission.

Martian Dust Devil Action in Gale Crater, Sol 1597

NASA Image and Video Library

2017-02-27

This frame from a sequence of images shows a dust-carrying whirlwind, called a dust devil, scooting across the ground inside Gale Crater, as observed on the local summer afternoon of NASA's Curiosity Mars Rover's 1,597th Martian day, or sol (Feb. 1, 2017). Set within a broader southward view from the rover's Navigation Camera, the rectangular area outlined in black was imaged multiple times over a span of several minutes to check for dust devils. Images from the period with most activity are shown in the inset area. The images are in pairs that were taken about 12 seconds apart, with an interval of about 90 seconds between pairs. Timing is accelerated and not fully proportional in this animation. A dust devil is most evident in the 10th, 11th and 12th frames. In the first and fifth frames, dust blowing across the ground appears as pale horizontal streak. Contrast has been modified to make frame-to-frame changes easier to see. A black frame is added between repeats of the sequence. On Mars as on Earth, dust devils are whirlwinds that result from sunshine warming the ground, prompting convective rising of air that has gained heat from the ground. Observations of Martian dust devils provide information about wind directions and interaction between the surface and the atmosphere. An animation is available at http://photojournal.jpl.nasa.gov/catalog/PIA21270

Orbitally modulated dust formation by the WC7+O5 colliding-wind binary WR140

NASA Astrophysics Data System (ADS)

Williams, P. M.; Marchenko, S. V.; Marston, A. P.; Moffat, A. F. J.; Varricatt, W. P.; Dougherty, S. M.; Kidger, M. R.; Morbidelli, L.; Tapia, M.

2009-05-01

We present high-resolution infrared (2-18 μm) images of the archetypal periodic dust-making Wolf-Rayet binary system WR140 (HD 193793) taken between 2001 and 2005, and multi-colour (J - [19.5]) photometry observed between 1989 and 2001. The images resolve the dust cloud formed by WR140 in 2001, allowing us to track its expansion and cooling, while the photometry allows tracking the average temperature and total mass of the dust. The combination of the two data sets constrains the optical properties of the dust, and suggests that they differ from those of the dust made by the WC9 dust-makers, including the classical `pinwheel', WR104. The photometry of individual dust emission features shows them to be significantly redder in (nbL'-[3.99]), but bluer in ([7.9]-[12.5]), than the binary, as expected from the spectra of heated dust and the stellar wind of a Wolf-Rayet star. The most persistent dust features, two concentrations at the ends of a `bar' of emission to the south of the star, were observed to move with constant proper motions of 324 +/- 8 and 243 +/- 7 mas yr-1. Longer wavelength (4.68 and 12.5 μm) images show dust emission from the corresponding features from the previous (1993) periastron passage and dust formation episode, showing that the dust expanded freely in a low-density void for over a decade, with dust features repeating from one cycle to the next. A third persistent dust concentration to the east of the binary (the `arm') was found to have a proper motion ~320 mas yr-1, and a dust mass about one-quarter that of the `bar'. Extrapolation of the motions of the concentrations back to the binary suggests that the eastern `arm' began expansion four to five months earlier than those in the southern `bar', consistent with the projected rotation of the binary axis and wind-collision region (WCR) on the sky. A comparison of model dust images and the observations constrains the intervals when the WCR was producing sufficiently compressed wind for dust nucleation in the WCR, and suggests that the distribution of this material was not uniform about the axis of the WCR, but more abundant in the following edge in the orbital plane.

Spectral mixture modeling - A new analysis of rock and soil types at the Viking Lander 1 site. [on Mars

NASA Technical Reports Server (NTRS)

Adams, J. B.; Smith, M. O.; Johnson, P. E.

1986-01-01

A Viking Lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust, gray andesitelike rock, and a coarse rocklike soil. The rocks are covered to varying degrees by dust but otherwise appear unweathered. Rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander. This soil probably is derived from the rocks by wind abrasion and/or spallation. Dust is the major component of the soil and covers most of the surface. The dust is unrelated spectrally to the rock but is equivalent to the global-scale dust observed telescopically. A new method was developed to model a multispectral image as mixtures of end-member spectra and to compare image spectra directly with laboratory reference spectra. The method for the first time uses shade and secondary illumination effects as spectral end-members; thus the effects of topography and illumination on all scales can be isolated or removed. The image was calibrated absolutely from the laboratory spectra, in close agreement with direct calibrations. The method has broad applications to interpreting multispectral images, including satellite images.

Atmospheric imaging results from the Mars Exploration Rovers

NASA Astrophysics Data System (ADS)

Lemmon, M.; Athena Science Team

The Athena science payload of the Spirit and Opportunity Mars Exploration Rovers contains instruments capable of measuring radiometric properties of the Martian atmosphere in the visible and the thermal infrared. Remote sensing instruments include Pancam, a color panoramic camera covering 0.4-1.0 microns, and Mini-TES, a thermal infrared spectrometer covering 5-29 microns. Results from atmospheric imaging by Pancam will be covered here. Visible and near-infrared aerosol opacity is monitored by direct solar imaging. Early results show dust opacity near 1 when both rovers landed. Both Spirit and Opportunity have seen dust opacity fall with time, somewhat faster at Spirit's Gusev crater landing site. Diurnal variations are also being monitored at both sites. There is no direct probe of the dust's vertical distribution, but images of the Sun near the horizon and of the twilight will provide constraints on the dust distribution. Dust optical properties and a cross-section weighted aerosol size will be estimated from Pancam images of the sky at varying geometries and times of day. A series of sky imaging sequences has been run with varying illumination geometry. The observations are similar to those reported for Mars Pathfinder.

Curiosity ChemCam Removes Dust

NASA Image and Video Library

2013-04-08

This pair of images taken a few minutes apart show how laser firing by NASA Mars rover Curiosity removes dust from the surface of a rock. The images were taken by the remote micro-imager camera in the laser-firing Chemistry and Camera ChemCam.

Dust Mantle Near Pavonis Mons

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-356, 10 May 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a thick mantle of dust covering lava flows north of Pavonis Mons so well that the flows are no longer visible. Flows are known to occur here because of the proximity to the volcano, and such flows normally have a very rugged surface. Fine dust, however, has settled out of the atmosphere over time and obscured the flows from view. The cliff at the top of the image faces north (up), the cliff in the middle of the image faces south (down), and the rugged slope at the bottom of the image faces north (up). The dark streak at the center-left was probably caused by an avalanche of dust sometime in the past few decades. The image is located near 4.1oN, 111.3oW. Sunlight illuminates the scene from the right/lower right.

Pancam and Microscopic Imager observations of dust on the Spirit Rover: Cleaning events, spectral properties, and aggregates

USGS Publications Warehouse

Vaughan, Alicia F.; Johnson, Jeffrey R.; Herkenhoff, Kenneth E.; Sullivan, Robert; Landis, Geoffrey A.; Goetz, Walter; Madsen, Morten B.

2010-01-01

This work describes dust deposits on the Spirit Rover over 2000 sols through examination of Pancam and Microscopic Imager observations of specific locations on the rover body, including portions of the solar array, Pancam and Mini-TES calibration targets, and the magnets. This data set reveals the three "cleaning events" experienced by Spirit to date, the spectral properties of dust, and the tendency of dust particles to form aggregates 100 um and larger.

Airport Activity Statistics of Certified Route Air Carriers: Calendar Year 1991

DTIC Science & Technology

1991-12-31

M otitpeilier/Barre Battle Creek, Ml . ...... .... ...... .................... ... Kalamazoo/Battle Creek Bay City. M l...Saginaw,/ Bay City/M idland Beaufori. NC...Green Bay /Clintonville Cody, WY................................................ . .. . .. .. . .. . .. . Lovell/ Powell[/Codyv Coffeyville

Cody Miller Initiative for Safer Prescriptions Act

THOMAS, 113th Congress

Sen. Gillibrand, Kirsten E. [D-NY

2013-04-17

Senate - 04/17/2013 Read twice and referred to the Committee on Health, Education, Labor, and Pensions. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

Cody Miller Initiative for Safer Prescriptions Act

THOMAS, 112th Congress

Sen. Gillibrand, Kirsten E. [D-NY

2012-05-22

Senate - 05/22/2012 Read twice and referred to the Committee on Health, Education, Labor, and Pensions. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

3-D Simulations of the Inner Dust Comae for Comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Marschall, Raphael; Liao, Ying; Su, Cheng-Chin; Wu, Jong-Shinn; Thomas, Nicolas; Rubin, Martin; Lai, Ian Lin; Ip, Wing-Huen; Keller, Horst Uwe; Knollenberg, Jörg; Kührt, Ekkehard; Skorov, Yuri; Altwegg, Kathrin; Vincent, Jean-Baptiste; Gicquel, Adeline; Shi, Xian; Sierks, Holger; Naletto, Giampiero

2015-04-01

The aims of this study are to (1) model the gas flow-field in the innermost coma for a plausible activity distributions of ROSETTA's target comet 67P/Churyumov-Gerasimenko (67P) using the SHAP2 model, (2) compare this with the ROSINA/COPS gas density (3) investigate the acceleration of dust by gas drag and the resulting dust distribution, (4) produce artificial images of the dust coma brightness as seen from different viewing geometries for a range of heliocentric distances and (5) compare the artificial images quantitatively with observations by the OSIRIS imaging system. We calculate the dust distribution in the coma within the first ten kilometers of the nucleus by assuming the dust to be spherical test particles in the gas field without any back coupling. The motion of the dust is driven by the drag force resulting from the gas flow. We assume a quadratic drag force with a velocity and temperature-dependent drag coefficient. The gravitational force of a point nucleus on the dust is also taken into account which will e.g. determine the maximal liftable size of the dust. Surface cohesion is not included. 40 dust sizes in the range between 8 nm and 0.3 mm are considered. For every dust size the dust densities and velocities are calculated by tracking around one million simulation particles in the gas field. We assume the distribution of dust according to size follows a power law, specifically the number of particles n or a particular radius r is specified by n ~ r-β with usual values of 3 ≤ β ≤ 4 where β = 3 corresponds to the case of equal mass per size and β = 4 to a shift of the mass towards the small particles. For the comparison with images of the high resolution camera OSIRIS on board ESAs ROSETTA spacecraft the viewing geometry of the camera can be specified and a line of sight integration through the dust density is performed. By means of Mie scattering on the particles the dust brightness can be determined. A variety of dust size distributions, gas to dust mass ratios, wavelengths and optical properties can thus be studied and compared with the data.

Policy implications for familial searching

PubMed Central

2011-01-01

In the United States, several states have made policy decisions regarding whether and how to use familial searching of the Combined DNA Index System (CODIS) database in criminal investigations. Familial searching pushes DNA typing beyond merely identifying individuals to detecting genetic relatedness, an application previously reserved for missing persons identifications and custody battles. The intentional search of CODIS for partial matches to an item of evidence offers law enforcement agencies a powerful tool for developing investigative leads, apprehending criminals, revitalizing cold cases and exonerating wrongfully convicted individuals. As familial searching involves a range of logistical, social, ethical and legal considerations, states are now grappling with policy options for implementing familial searching to balance crime fighting with its potential impact on society. When developing policies for familial searching, legislators should take into account the impact of familial searching on select populations and the need to minimize personal intrusion on relatives of individuals in the DNA database. This review describes the approaches used to narrow a suspect pool from a partial match search of CODIS and summarizes the economic, ethical, logistical and political challenges of implementing familial searching. We examine particular US state policies and the policy options adopted to address these issues. The aim of this review is to provide objective background information on the controversial approach of familial searching to inform policy decisions in this area. Herein we highlight key policy options and recommendations regarding effective utilization of familial searching that minimize harm to and afford maximum protection of US citizens. PMID:22040348

Policy implications for familial searching.

PubMed

Kim, Joyce; Mammo, Danny; Siegel, Marni B; Katsanis, Sara H

2011-11-01

In the United States, several states have made policy decisions regarding whether and how to use familial searching of the Combined DNA Index System (CODIS) database in criminal investigations. Familial searching pushes DNA typing beyond merely identifying individuals to detecting genetic relatedness, an application previously reserved for missing persons identifications and custody battles. The intentional search of CODIS for partial matches to an item of evidence offers law enforcement agencies a powerful tool for developing investigative leads, apprehending criminals, revitalizing cold cases and exonerating wrongfully convicted individuals. As familial searching involves a range of logistical, social, ethical and legal considerations, states are now grappling with policy options for implementing familial searching to balance crime fighting with its potential impact on society. When developing policies for familial searching, legislators should take into account the impact of familial searching on select populations and the need to minimize personal intrusion on relatives of individuals in the DNA database. This review describes the approaches used to narrow a suspect pool from a partial match search of CODIS and summarizes the economic, ethical, logistical and political challenges of implementing familial searching. We examine particular US state policies and the policy options adopted to address these issues. The aim of this review is to provide objective background information on the controversial approach of familial searching to inform policy decisions in this area. Herein we highlight key policy options and recommendations regarding effective utilization of familial searching that minimize harm to and afford maximum protection of US citizens.

Internal validation of the DNAscan/ANDE™ Rapid DNA Analysis™ platform and its associated PowerPlex® 16 high content DNA biochip cassette for use as an expert system with reference buccal swabs.

PubMed

Moreno, Lilliana I; Brown, Alice L; Callaghan, Thomas F

2017-07-01

Rapid DNA platforms are fully integrated systems capable of producing and analyzing short tandem repeat (STR) profiles from reference sample buccal swabs in less than two hours. The technology requires minimal user interaction and experience making it possible for high quality profiles to be generated outside an accredited laboratory. The automated production of point of collection reference STR profiles could eliminate the time delay for shipment and analysis of arrestee samples at centralized laboratories. Furthermore, point of collection analysis would allow searching against profiles from unsolved crimes during the normal booking process once the infrastructure to immediately search the Combined DNA Index System (CODIS) database from the booking station is established. The DNAscan/ANDE™ Rapid DNA Analysis™ System developed by Network Biosystems was evaluated for robustness and reliability in the production of high quality reference STR profiles for database enrollment and searching applications. A total of 193 reference samples were assessed for concordance of the CODIS 13 loci. Studies to evaluate contamination, reproducibility, precision, stutter, peak height ratio, noise and sensitivity were also performed. The system proved to be robust, consistent and dependable. Results indicated an overall success rate of 75% for the 13 CODIS core loci and more importantly no incorrect calls were identified. The DNAscan/ANDE™ could be confidently used without human interaction in both laboratory and non-laboratory settings to generate reference profiles. Published by Elsevier B.V.

Infrared fluorescent automated detection of thirteen short tandem repeat polymorphisms and one gender-determining system of the CODIS core system.

PubMed

Ricci, U; Sani, I; Guarducci, S; Biondi, C; Pelagatti, S; Lazzerini, V; Brusaferri, A; Lapini, M; Andreucci, E; Giunti, L; Giovannucci Uzielli, M L

2000-11-01

We used an infrared (IR) automated fluorescence monolaser sequencer for the analysis of 13 autosomal short tandem repeat (STR) systems (TPOX, D3S1358, FGA, CSF1PO, D5S818, D7S820, D8S1179, TH01, vWA, D13S317, D16S359, D18S51, D21S11) and the X-Y homologous gene amelogenin system. These two systems represent the core of the combined DNA index systems (CODIS). Four independent multiplex reactions, based on the polymerase chain reaction (PCR) technique and on the direct labeling of the forward primer of every primer pair, with a new molecule (IRDye800), were set up, permitting the exact characterization of the alleles by comparison with ladders of specific sequenced alleles. This is the first report of the whole analysis of the STRs of the CODIS core using an IR automated DNA sequencer. The protocol was used to solve paternity/maternity tests and for population studies. The electrophoretic system also proved useful for the correct typing of those loci differing in size by only 2 bp. A sensibility study demonstrated that the test can detect an average of 10 pg of undegraded human DNA. We also performed a preliminary study analyzing some forensic samples and mixed stains, which suggested the usefulness of using this analytical system for human identification as well as for forensic purposes.

Seeking Planets in the Dust Artist Concept

NASA Image and Video Library

2014-12-02

A dusty planetary system left is compared to another system with little dust in this artist concept. Dust can make it difficult for telescopes to image planets because light from the dust can outshine that of the planets.

China Dust and Sand

Atmospheric Science Data Center

2013-04-16

... article title:  Dust and Sand Sweep Over Northeast China     View Larger Image ... these views of the dust and sand that swept over northeast China on March 10, 2004. Information on the height of the dust and an ...

Identification of Dust Source Regions at High-Resolution and Dynamics of Dust Source Mask over Southwest United States Using Remote Sensing Data

NASA Astrophysics Data System (ADS)

Sprigg, W. A.; Sahoo, S.; Prasad, A. K.; Venkatesh, A. S.; Vukovic, A.; Nickovic, S.

2015-12-01

Identification and evaluation of sources of aeolian mineral dust is a critical task in the simulation of dust. Recently, time series of space based multi-sensor satellite images have been used to identify and monitor changes in the land surface characteristics. Modeling of windblown dust requires precise delineation of mineral dust source and its strength that varies over a region as well as seasonal and inter-annual variability due to changes in land use and land cover. Southwest USA is one of the major dust emission prone zone in North American continent where dust is generated from low lying dried-up areas with bare ground surface and they may be scattered or appear as point sources on high resolution satellite images. In the current research, various satellite derived variables have been integrated to produce a high-resolution dust source mask, at grid size of 250 m, using data such as digital elevation model, surface reflectance, vegetation cover, land cover class, and surface wetness. Previous dust source models have been adopted to produce a multi-parameter dust source mask using data from satellites such as Terra (Moderate Resolution Imaging Spectroradiometer - MODIS), and Landsat. The dust source mask model captures the topographically low regions with bare soil surface, dried-up river plains, and lakes which form important source of dust in southwest USA. The study region is also one of the hottest regions of USA where surface dryness, land use (agricultural use), and vegetation cover changes significantly leading to major changes in the areal coverage of potential dust source regions. A dynamic high resolution dust source mask have been produced to address intra-annual change in the aerial extent of bare dry surfaces. Time series of satellite derived data have been used to create dynamic dust source masks. A new dust source mask at 16 day interval allows enhanced detection of potential dust source regions that can be employed in the dust emission and transport pathways models for better estimation of emission of dust during dust storms, particulate air pollution, public health risk assessment tools and decision support systems.

Interstellar matter in Shapley-Ames elliptical galaxies. II. The distribution of dust and ionized gas

NASA Astrophysics Data System (ADS)

Goudfrooij, P.; Hansen, L.; Jorgensen, H. E.; Norgaard-Nielsen, H. U.

1994-06-01

We present results of deep optical CCD imaging for a complete, optical magnitude-limited sample of 56 elliptical galaxies from the RSA catalog. For each galaxy we have obtained broad-band images (in B, V, and I) and narrow-band images using interference filters isolating the Hα+[NII] emission lines to derive the amount and morphology of dust and ionized gas. Detailed consideration of systematic errors due to effects of sky background subtraction and removal of stellar continuum light from the narrow-band images is described. The flux calibration of the narrow-band images is performed by deconvolving actually measured spectral energy distributions with the filter transmission curves. We also present optical long-slit spectroscopy to determine the [NII]/Hα intensity ratio of the ionized gas. Dust lanes and/or patches have been detected in 23 galaxies (41%) from this sample using both colour-index images and division by purely elliptical model images. We achieved a detection limit for dust absorption of A_B_~0.02. Accounting for selection effects, the true fraction of elliptical galaxies containing dust is estimated to be of order 80%. This detection rate is comparable to that of the IRAS satellite, and significantly larger than results of previous optical studies. Ionized gas has been detected in 32 galaxies (57%). The spectroscopic data confirm the presence and distribution of ionized gas as seen in the direct imaging. All elliptical galaxies in our sample in which a number of emission lines is detected show very similar emission-line intensity ratios, which are typical of LINER nuclei. The amounts of detectable dust and ionized gas are generally small--of order 10^4^-10^5^Msun_ of dust and 10^3^-10^4^Msun_ of ionized gas. The dust and ionized gas show a wide variety of distributions-extended along either the apparent major axis, or the minor axis, or a skewed axis, indicating that triaxiality is in general required as a galaxy figure. In some cases (NGC 1275, NGC 2325, NGC 3136, NGC 3962, NGC 4696, NGC 5018, NGC 5044, NGC 5813, IC 1459) the interstellar matter has a patchy or filamentary distribution, suggestive of a recent interaction event. The distributions of dust and ionized gas are consistent with being physically associated with each other.

Swirling Dust in Gale Crater, Mars, Sol 1613

NASA Image and Video Library

2017-02-27

This frame from a sequence of images shows a dust-carrying whirlwind, called a dust devil, on lower Mount Sharp inside Gale Crater, as viewed by NASA's Curiosity Mars Rover during the summer afternoon of the rover's 1,613rd Martian day, or sol (Feb. 18, 2017). Set within a broader southward view from the rover's Navigation Camera, the rectangular area outlined in black was imaged multiple times over a span of several minutes to check for dust devils. Images from the period with most activity are shown in the inset area. The images are in pairs that were taken about 12 seconds apart, with an interval of about 90 seconds between pairs. Timing is accelerated and not fully proportional in this animation. Contrast has been modified to make frame-to-frame changes easier to see. A black frame provides a marker between repeats of the sequence. On Mars as on Earth, dust devils result from sunshine warming the ground, prompting convective rising of air that has gained heat from the ground. Observations of dust devils provide information about wind directions and interaction between the surface and the atmosphere. An animation is available at http://photojournal.jpl.nasa.gov/catalog/PIA21483

The dust environment of 67P/Churyumov-Gerasimenko as seen through Rosetta/OSIRIS

NASA Astrophysics Data System (ADS)

Tubiana, Cecilia; Bertini, Ivano; Deller, Jakob; Drolshagen, Esther; Frattin, Elisa; Güttler, Carsten; Hofmann, Marc; Koschny, Detlef; Oklay, Nilda; Ott, Theresa; Shi, Xian; Sierks, Holger; Vincent, Jean-Baptiste; OSIRIS Team

2016-10-01

The ESA's Rosetta spacecraft had the unique opportunity to stay in the vicinity of the comet for two years, observing how the comet evolved while approaching the Sun, passing through perihelion and then moving outwards. OSIRIS, the Optical, Spectroscopic, and Infrared Remote Imaging System onboard Rosetta, imaged the nucleus and the dust environment of 67/Churyumov-Gerasimenko since the beginning of post-hibernation operations in March 2014. We focus here on dust studies carried on with OSIRIS.Images obtained in different filters in the visible wavelength range have been used to study the unresolved dust coma, investigating its diurnal and seasonal variations and providing insights into the dust composition. A correlation has been found between the level of diurnal activity and the region of the nucleus surface in sunlight, suggesting that the topography and/or composition of the surface play an important role. The overall activity increases while the comet is approaching the Sun, peaking about a month after perihelion. Comparison with ground-based observations will allow to understand if the dust coma behaves in similar ways at small scales - as observed by Rosetta/OSIRIS - and at large scales - as observed from ground. Several times during the mission, we acquired images spanning the phase angle range 0-165 degrees. They are used to determine the dust phase function in different wavelengths, its evolution with heliocentric distance and to investigate the intimate nature of cometary dust aggregates by solving the inverse scattering problem. A large amount of individual aggregates is present in the vicinity of 67P/Churyumov-Gerasimenko. We used OSIRIS NAC and WAC images to determine the aggregate properties: size and distance distributions, colors and rotation. Thanks to observations performed at different heliocentric distances, we address how those properties are changing with heliocentric distance.

COLLISIONAL GROOMING MODELS OF THE KUIPER BELT DUST CLOUD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuchner, Marc J.; Stark, Christopher C., E-mail: Marc.Kuchner@nasa.go, E-mail: starkc@umd.ed

2010-10-15

We modeled the three-dimensional structure of the Kuiper Belt (KB) dust cloud at four different dust production rates, incorporating both planet-dust interactions and grain-grain collisions using the collisional grooming algorithm. Simulated images of a model with a face-on optical depth of {approx}10{sup -4} primarily show an azimuthally symmetric ring at 40-47 AU in submillimeter and infrared wavelengths; this ring is associated with the cold classical KB. For models with lower optical depths (10{sup -6} and 10{sup -7}), synthetic infrared images show that the ring widens and a gap opens in the ring at the location of Neptune; this feature ismore » caused by trapping of dust grains in Neptune's mean motion resonances. At low optical depths, a secondary ring also appears associated with the hole cleared in the center of the disk by Saturn. Our simulations, which incorporate 25 different grain sizes, illustrate that grain-grain collisions are important in sculpting today's KB dust, and probably other aspects of the solar system dust complex; collisions erase all signs of azimuthal asymmetry from the submillimeter image of the disk at every dust level we considered. The model images switch from being dominated by resonantly trapped small grains ('transport dominated') to being dominated by the birth ring ('collision dominated') when the optical depth reaches a critical value of {tau} {approx} v/c, where v is the local Keplerian speed.« less

76 FR 2190 - Qualification of Drivers; Exemption Applications; Vision

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-12

.... The exemptions expire on January 12, 2012. FOR FURTHER INFORMATION CONTACT: Dr. Mary D. Gunnels..., Donald G. Brock, Jr., Anthony D. Buck, Cody W. Cook, Marvin R. Daly, Douglas R. Duncan, Douglas K. Esp...

Seeing Beyond the Monkey Head

NASA Image and Video Library

2015-08-20

Scores of baby stars shrouded by dust are revealed in this infrared image of the star-forming region NGC 2174, as seen by NASA Spitzer Space Telescope. Found in the constellation Orion, NGC 2174 is located around 6,400 light-years away. Some of the clouds in the region resemble the face of a monkey in visible-light images, hence the nebula's nickname: the "Monkey Head." However, in infrared images such as this, the monkey disappears. That's because different clouds are highlighted in infrared and visible-light images. Found in the northern reaches of the constellation Orion, NGC 2174 is located around 6,400 light-years away. Columns of dust, slightly to the right of center in the image, are being carved out of the dust by radiation and stellar winds from the hottest young stars recently born in the area. Spitzer's infrared view provides us with a preview of the next clusters of stars that will be born in the coming millennia. The reddish spots of light scattered through the darker filaments are infant stars swaddled by blankets of warm dust. The warm dust glows brightly at infrared wavelengths. Eventually, these stars will pop out of their dusty envelopes and their light will carve away at the dust clouds surrounding them. In this image, infrared wavelengths have been assigned visible colors we see with our eyes. Light with a wavelength of 3.5 microns is shown in blue, 8.0 microns is green, and 24 microns in red. The greens show the organic molecules in the dust clouds, illuminated by starlight. Reds are caused by the thermal radiation emitted from the very hottest areas of dust. Areas around the edges that were not observed by Spitzer have been filled in using infrared observations from NASA's Wide Field Infrared Survey Explorer, or WISE. http://photojournal.jpl.nasa.gov/catalog/PIA19836

A Dust Devil Making a Streak and Climbing a Crater Wall

NASA Technical Reports Server (NTRS)

2002-01-01

MGS MOC Release No. MOC2-318, 8 August 2002 [figure removed for brevity, see original site] One of the key elements of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is to look for and monitor changes taking place on the planet over the course of a second--and, eventually, a third--martian year. MGS is now well into its second Mars year, which will draw to a close in December 2002. Among the changes the MOC has observed are streaks believed to be caused by the passage of dust devils. Thousands of MOC images show these streaks, dozens show that they change over time, but far fewer images have actually captured a dust devil in the act of creating a streak. At the center right of this image (above left) is a dust devil that, on May 21, 2002, was seen climbing the wall of a crater at 4.1oS, 9.5oW. This crater (above right) is in western Terra Meridiani. The dust devil was moving toward the northeast (upper right), leaving behind a dark trail where a thin coating of surficial dust was removed or disrupted as the dust devil advanced. Dust devils most commonly form after noon on days when the martian air is still (that is, when there isn't even a faint breeze). On such days, the ground is better able to heat up the air immediately above the surface. As the warmed near-surface air begins to rise, it also begins to spin, creating a vortex. The spinning column then moves across the surface and picks up loose dust (if any is present). The dust makes the vortex visible and gives it a tornado-like appearance. The dust devil in this image has a very short, dark shadow cast to the right of the bright column; this shadow is short because the sun was nearly overhead.

Gone with the heat: a fundamental constraint on the imaging of dust and molecular gas in the early Universe.

PubMed

Zhang, Zhi-Yu; Papadopoulos, Padelis P; Ivison, R J; Galametz, Maud; Smith, M W L; Xilouris, Emmanuel M

2016-06-01

Images of dust continuum and carbon monoxide (CO) line emission are powerful tools for deducing structural characteristics of galaxies, such as disc sizes, H2 gas velocity fields and enclosed H2 and dynamical masses. We report on a fundamental constraint set by the cosmic microwave background (CMB) on the observed structural and dynamical characteristics of galaxies, as deduced from dust continuum and CO-line imaging at high redshifts. As the CMB temperature rises in the distant Universe, the ensuing thermal equilibrium between the CMB and the cold dust and H2 gas progressively erases all spatial and spectral contrasts between their brightness distributions and the CMB. For high-redshift galaxies, this strongly biases the recoverable H2 gas and dust mass distributions, scale lengths, gas velocity fields and dynamical mass estimates. This limitation is unique to millimetre/submillimetre wavelengths and unlike its known effect on the global dust continuum and molecular line emission of galaxies, it cannot be addressed simply. We nevertheless identify a unique signature of CMB-affected continuum brightness distributions, namely an increasing rather than diminishing contrast between such brightness distributions and the CMB when the cold dust in distant galaxies is imaged at frequencies beyond the Raleigh-Jeans limit. For the molecular gas tracers, the same effect makes the atomic carbon lines maintain a larger contrast than the CO lines against the CMB.

The Martian Story Ares 4 Landing Site

NASA Image and Video Library

2015-10-05

This image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter shows a location on Mars associated with the best-selling novel and Hollywood movie, "The Martian." It is the science-fiction tale's planned landing site for the Ares 4 mission. The novel placed the Ares 4 site on the floor of a very shallow crater in the southwestern corner of Schiaparelli Crater. This HiRISE image shows a flat region there entirely mantled by bright Martian dust. There are no color variations, just uniform reddish dust. A pervasive, pitted texture visible at full resolution is characteristic of many dust deposits on Mars. No boulders are visible, so the dust is probably at least a meter thick. Past Martian rover and lander missions from NASA have avoided such pervasively dust-covered regions for two reasons. First, the dust has a low thermal inertia, meaning that it gets extra warm in the daytime and extra cold at night, a thermal challenge to survival of the landers and rovers (and people). Second, the dust hides the bedrock, so little is known about the bedrock composition and whether it is of scientific interest. This view is one image product from HiRISE observation ESP_042014_1760, taken July 14, 2015, at 3.9 degrees south latitude, 15.2 degrees east longitude. http://photojournal.jpl.nasa.gov/catalog/PIA19914

Identification of dust storm source areas in West Asia using multiple environmental datasets.

PubMed

Cao, Hui; Amiraslani, Farshad; Liu, Jian; Zhou, Na

2015-01-01

Sand and Dust storms are common phenomena in arid and semi-arid areas. West Asia Region, especially Tigris-Euphrates alluvial plain, has been recognized as one of the most important dust source areas in the world. In this paper, a method is applied to extract SDS (Sand and Dust Storms) sources in West Asia region using thematic maps, climate and geography, HYSPLIT model and satellite images. Out of 50 dust storms happened during 2000-2013 and collected in form of MODIS images, 27 events were incorporated as demonstrations of the simulated trajectories by HYSPLIT model. Besides, a dataset of the newly released Landsat images was used as base-map for the interpretation of SDS source regions. As a result, six main clusters were recognized as dust source areas. Of which, 3 clusters situated in Tigris-Euphrates plain were identified as severe SDS sources (including 70% dust storms in this research). Another cluster in Sistan plain is also a potential source area. This approach also confirmed six main paths causing dust storms. These paths are driven by the climate system including Siberian and Polar anticyclones, monsoon from Indian Subcontinent and depression from north of Africa. The identification of SDS source areas and paths will improve our understandings on the mechanisms and impacts of dust storms on socio-economy and environment of the region. Copyright © 2014 Elsevier B.V. All rights reserved.

a Comparison of Empirical and Inteligent Methods for Dust Detection Using Modis Satellite Data

NASA Astrophysics Data System (ADS)

Shahrisvand, M.; Akhoondzadeh, M.

2013-09-01

Nowadays, dust storm in one of the most important natural hazards which is considered as a national concern in scientific communities. This paper considers the capabilities of some classical and intelligent methods for dust detection from satellite imagery around the Middle East region. In the study of dust detection, MODIS images have been a good candidate due to their suitable spectral and temporal resolution. In this study, physical-based and intelligent methods including decision tree, ANN (Artificial Neural Network) and SVM (Support Vector Machine) have been applied to detect dust storms. Among the mentioned approaches, in this paper, SVM method has been implemented for the first time in domain of dust detection studies. Finally, AOD (Aerosol Optical Depth) images, which are one the referenced standard products of OMI (Ozone Monitoring Instrument) sensor, have been used to assess the accuracy of all the implemented methods. Since the SVM method can distinguish dust storm over lands and oceans simultaneously, therefore the accuracy of SVM method is achieved better than the other applied approaches. As a conclusion, this paper shows that SVM can be a powerful tool for production of dust images with remarkable accuracy in comparison with AOT (Aerosol Optical Thickness) product of NASA.

Devilish Details

NASA Technical Reports Server (NTRS)

2005-01-01

23 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small, springtime dust devil creating a dark streak on the plains of Argyre. The small, bright dot is the dust devil. Many other dark streaks on the plains indicate the areas where other dust devils had passed within the past several weeks before this July 2005 image was acquired.

Location near: 44.6oS, 40.3oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

Scientific assessment of the quality of OSIRIS images

NASA Astrophysics Data System (ADS)

Tubiana, C.; Güttler, C.; Kovacs, G.; Bertini, I.; Bodewits, D.; Fornasier, S.; Lara, L.; La Forgia, F.; Magrin, S.; Pajola, M.; Sierks, H.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; Rickman, H.; Keller, H. U.; Agarwal, J.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Besse, S.; Boudreault, S.; Cremonese, G.; Da Deppo, V.; Davidsson, B.; Debei, S.; De Cecco, M.; El-Maarry, M. R.; Fulle, M.; Groussin, O.; Gutiérrez-Marques, P.; Gutiérrez, P. J.; Hoekzema, N.; Hofmann, M.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Knollenberg, J.; Kramm, J.-R.; Kührt, E.; Küppers, M.; Lazzarin, M.; Lopez Moreno, J. J.; Marzari, F.; Massironi, M.; Michalik, H.; Moissl, R.; Naletto, G.; Oklay, N.; Scholten, F.; Shi, X.; Thomas, N.; Vincent, J.-B.

2015-11-01

Context. OSIRIS, the scientific imaging system onboard the ESA Rosetta spacecraft, has been imaging the nucleus of comet 67P/Churyumov-Gerasimenko and its dust and gas environment since March 2014. The images serve different scientific goals, from morphology and composition studies of the nucleus surface, to the motion and trajectories of dust grains, the general structure of the dust coma, the morphology and intensity of jets, gas distribution, mass loss, and dust and gas production rates. Aims: We present the calibration of the raw images taken by OSIRIS and address the accuracy that we can expect in our scientific results based on the accuracy of the calibration steps that we have performed. Methods: We describe the pipeline that has been developed to automatically calibrate the OSIRIS images. Through a series of steps, radiometrically calibrated and distortion corrected images are produced and can be used for scientific studies. Calibration campaigns were run on the ground before launch and throughout the years in flight to determine the parameters that are used to calibrate the images and to verify their evolution with time. We describe how these parameters were determined and we address their accuracy. Results: We provide a guideline to the level of trust that can be put into the various studies performed with OSIRIS images, based on the accuracy of the image calibration.

Dust Storm Hits Canary Islands

NASA Technical Reports Server (NTRS)

2002-01-01

A thick pall of sand and dust blew out from the Sahara Desert over the Atlantic Ocean yesterday (January 6, 2002), engulfing the Canary Islands in what has become one of the worst sand storms ever recorded there. In this scene, notice how the dust appears particularly thick in the downwind wake of Tenerife, the largest of the Canary Islands. Perhaps the turbulence generated by the air currents flowing past the island's volcanic peaks is churning the dust back up into the atmosphere, rather than allowing it to settle toward the surface. This true-color image was captured by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on January 7, 2002. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

The Continuous Monitoring of Desert Dust using an Infrared-based Dust Detection and Retrieval Method

NASA Technical Reports Server (NTRS)

Duda, David P.; Minnis, Patrick; Trepte, Qing; Sun-Mack, Sunny

2006-01-01

Airborne dust and sand are significant aerosol sources that can impact the atmospheric and surface radiation budgets. Because airborne dust affects visibility and air quality, it is desirable to monitor the location and concentrations of this aerosol for transportation and public health. Although aerosol retrievals have been derived for many years using visible and near-infrared reflectance measurements from satellites, the detection and quantification of dust from these channels is problematic over bright surfaces, or when dust concentrations are large. In addition, aerosol retrievals from polar orbiting satellites lack the ability to monitor the progression and sources of dust storms. As a complement to current aerosol dust retrieval algorithms, multi-spectral thermal infrared (8-12 micron) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Meteosat-8 Spinning Enhanced Visible and Infrared Imager (SEVIRI) are used in the development of a prototype dust detection method and dust property retrieval that can monitor the progress of Saharan dust fields continuously, both night and day. The dust detection method is incorporated into the processing of CERES (Clouds and the Earth s Radiant Energy System) aerosol retrievals to produce dust property retrievals. Both MODIS (from Terra and Aqua) and SEVERI data are used to develop the method.

Dust storm off Western Africa

NASA Technical Reports Server (NTRS)

2002-01-01

The impacts of Saharan dust storms reach far beyond Africa. Wind-swept deserts spill airborne dust particles out over the Atlantic Ocean where they can enter trade winds bound for Central and North America and the Caribbean. This Moderate Resolution Imaging Spectroradiometer (MODIS) image shows a dust storm casting an opaque cloud of cloud across the Canary Islands and the Atlantic Ocean west of Africa on June 30, 2002. In general it takes between 5 and 7 days for such an event to cross the Atlantic. The dust has been shown to introduce foreign bacteria and fungi that have damaged reef ecosystems and have even been hypothesized as a cause of increasing occurrences of respiratory complaints in places like Florida, where the amount of Saharan dust reaching the state has been increasing over the past 25 years.

77 FR 74273 - Qualification of Drivers; Exemption Applications; Vision

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-13

... (SD) Terry L. Anderson (PA) Sammy J. Barada (NE) Timothy Bradford (TN) Cody W. Cook (OK) Marvin R...) Thomas L. Oglesby (GA) Garrick Pitts (AR) Jonathan C. Rollings (IA) Preston S. Salisbury (MT) Victor M...

View of the highway, looking west towards Little Bear Lake ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of the highway, looking west towards Little Bear Lake Fen where the fen bridge will be installed on the existing alignment - Beartooth Highway, Red Lodge, Montana to Cooke City, Montana, Cody, Park County, WY

View of the highway crossing Little Bear Lake Fen, looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of the highway crossing Little Bear Lake Fen, looking northeast. The fen bridge will be installed on the existing alignment - Beartooth Highway, Red Lodge, Montana to Cooke City, Montana, Cody, Park County, WY

Views of the Apollo 11 Twentieth Anniversary Black Tie reception

NASA Technical Reports Server (NTRS)

1989-01-01

View from the Apollo 11 Twentieth Anniversary Black Tie reception at the downtown Houston Hyatt Regency Hotel. Scene show NASA/JSC Director Aaron Cohen talking with NASA Administrator Richard H. Truly and his wife, Cody.

Active Lifting During Martian Dust Storm

NASA Image and Video Library

2017-03-09

This false-color scene from the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity documents movement of dust as a regional dust storm approached the rover's location on Feb. 24, 2017, during the 4,653rd Martian day, or sol, of the rover's work on Mars. Key to detecting the movement is that Pancam color images are combinations of different images taken a short time apart through different color filters. Note that along the horizon, the left portion of the image has a bluish band (with label and arrow in Figure 1). The component image admitting blue light was taken about 150 seconds after the component image admitting red light. A layer of dust-carrying wind hadn't reached this location by the earlier exposure, but had by the later one. This Sol 4653 Opportunity view is toward the north from the rover's location on the western rim of Endeavour Crater in the Meridiani Planum region of Mars. http://photojournal.jpl.nasa.gov/catalog/PIA21485

Indirect Charged Particle Detection: Concepts and a Classroom Demonstration

NASA Astrophysics Data System (ADS)

Childs, Nicholas B.; Horányi, Mihály; Collette, Andrew

2013-11-01

We describe the principles of macroscopic charged particle detection in the laboratory and their connections to concepts taught in the physics classroom. Electrostatic dust accelerator systems, capable of launching charged dust grains at hypervelocities (1-100 km/s), are a critical tool for space exploration. Dust grains in space typically have large speeds relative to the probes or satellites that encounter them. Development and testing of instruments that look for dust in space therefore depends critically on the availability of fast, well-characterized dust grains in the laboratory. One challenge for the experimentalist is to precisely measure the speed and mass of laboratory dust particles without disturbing them. Detection systems currently in use exploit the well-known effect of image charge to register the passage of dust grains without changing their speed or mass. We describe the principles of image charge detection and provide a simple classroom demonstration of the technique using soup cans and pith balls.

Dust Accumulation on Mars

NASA Technical Reports Server (NTRS)

2005-01-01

Since landing on Mars a year ago, NASA's pair of six-wheeled geologists have been constantly exposed to martian winds and dust. As a result, the Spirit rover has gradually experienced a slight decline in power as a thin layer of dust has accumulated on the solar panels, blocking some of the sunlight that is converted to electricity. In this enlarged image of a postage-stamp-size (3-centimeter-square, 1.2-inch-square) portion of one of Spirit's solar panels, a fine layer of martian dust coats electrical connections and metal surfaces. Individual silt grains or clumps of dust are visible where sediment has accumulated in crevices between solar cells and circuits. The upper right half of the image shows the edge of one of the rover's solar cells. The lower left half shows electrical wires bonded with silicon adhesive to the underlying composite surface; the circular abrasions are the result of sanding by hand on Earth. The braided wire is connected to a thermocouple used to measure temperature based on electrical resistance. Spirit took this image with its microscopic imager on martian day, or sol, 350 (Dec. 26, 2004).

The dust environment of 67P/Churyumov-Gerasimenko as seen through Rosetta/OSIRIS

NASA Astrophysics Data System (ADS)

Tubiana, C.; Güttler, C.; Sierks, H.; Bertini, I.; Osiris Team

2017-09-01

The ESA's Rosetta spacecraft had the unique opportunity to be in the vicinity of comet 67P/Churyumov-Gerasimenko for 2.5 years, observing how the comet evolved while approaching the Sun, passing through perihelion and then moving back into the outer solar system. OSIRIS, the scientific camera system onboard Rosetta, imaged the nucleus and the comet dust environment during the entire mission. We studied the unresolved dust coma, investigating its diurnal and seasonal variations and providing insights into the dust composition. Hundreds of individual particles, identified in the thousands of images dedicated to dust studies, have been characterized in terms of color, size distribution, distance, light curves and orbits.

Martian Dust Devils: 2 Mars Years of MGS MOC Observations

NASA Astrophysics Data System (ADS)

Cantor, B. A.; Edgett, K. S.

2002-12-01

Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide and narrow angle images have captured more than 1000 active dust devils over 2 Mars years. In the most recent Mars year, we repeatedly imaged (and are continuing to image) several areas to monitor dust devil occurrence. Some Mars dust devils are as small as a few to 10s of meters across, others are 100s of meters across and over 6 km high. Each Martian hemisphere has a "dust devil season" that generally follows the subsolar latitude. An exception is NW Amazonis, which has frequent, large dust devils throughout northern spring and summer (probably every afternoon; observations are acquired 2-3 times a week). The Amazonis and other MOC observations show no evidence that dust devils cause, lead to, or have a systematic relationship with dust storms. However, dust devils sometimes do occur near small, localized storms; and one specific relation occurred during the onset of the global dust events of 2001: slightly elevated levels of atmospheric dust (an optically thin cloud) triggered a very short period of dust devil activity in NW Amazonis in early northern autumn. The redistribution of dust by the 2001 global events may have also affected subsequent spring and summer dust devil activity in Hellas, where considerably fewer dust devils occurred in 2001-2002 than 1999-2000. In SW Syria, frequent, large dust devils occurred after the 2001 global events and persisted through southern summer. While dust devils have no specific relation to dust storms, they might play a role in the seasonal "wave of darkening" at middle and high latitudes by removing or disrupting thin veneers of dust. Dust devils have been observed to create thin, filamentary streaks. Some streaks are darker than their surroundings, while others are lighter. Some dust devils do not create streaks. At mid-latitudes, surfaces darken in spring as 100s of crisscrossing streaks form on widely-varied terrain. Some rare streaks exhibit cycloidal patterns similar to those created on Earth by tornadoes with multiple sub-vortices. The streaks occur at nearly all latitudes and elevations, from north polar dunes to the south polar layered terrain, from the summit of Olympus Mons to the floor of Hellas. During "dust devil season" at a given latitude, tremendous changes in streak patterns occur in periods as short as 1 month. These observations, along with repeated imaging in NW Amazonis and SW Syria, provide some idea of the frequency of dust devils. Uncertain is whether dust devils are responsible for all thin, filamentary streaks: while active vortices have been seen creating the plethora of streaks at southern mid-latitudes, none have been observed on the northern plains, despite observation of similar streak patterns. Perhaps northern plains dust devils occur at a different time of day relative to the MGS 1400 LT orbit, or perhaps dust devils did not form them. We monitored removal of dust from surfaces after the 2001 global dust events in several locations. Of particular interest was western Syrtis Major, which had brightened considerably after the 2001 storms. We observed this area for several months while very little change occurred. Finally, in January 2002, the surface was swept clean of most of its 2001 veneer of dust in a period of about 1 week. Dust devils played no role in this process; instead, regional surface winds were responsible.

Retrieving Atmospheric Dust Loading on Mars Using Engineering Cameras and MSL's Mars Hand Lens Imager (MAHLI)

NASA Astrophysics Data System (ADS)

Wolfe, C. A.; Lemmon, M. T.

2015-12-01

Dust in the Martian atmosphere influences energy deposition, dynamics, and the viability of solar powered exploration vehicles. The Viking, Pathfinder, Spirit, Opportunity, Phoenix, and Curiosity landers and rovers each included the ability to image the Sun with a science camera equipped with a neutral density filter. Direct images of the Sun not only provide the ability to measure extinction by dust and ice in the atmosphere, but also provide a variety of constraints on the Martian dust and water cycles. These observations have been used to characterize dust storms, to provide ground truth sites for orbiter-based global measurements of dust loading, and to help monitor solar panel performance. In the cost-constrained environment of Mars exploration, future missions may omit such cameras, as the solar-powered InSight mission has. We seek to provide a robust capability of determining atmospheric opacity from sky images taken with cameras that have not been designed for solar imaging, such as the engineering cameras onboard Opportunity and the Mars Hand Lens Imager (MAHLI) on Curiosity. Our investigation focuses primarily on the accuracy of a method that determines optical depth values using scattering models that implement the ratio of sky radiance measurements at different elevation angles, but at the same scattering angle. Operational use requires the ability to retrieve optical depth on a timescale useful to mission planning, and with an accuracy and precision sufficient to support both mission planning and validating orbital measurements. We will present a simulation-based assessment of imaging strategies and their error budgets, as well as a validation based on the comparison of direct extinction measurements from archival Navcam, Hazcam, and MAHLI camera data.

Dust measurements in tokamaks (invited).

PubMed

Rudakov, D L; Yu, J H; Boedo, J A; Hollmann, E M; Krasheninnikov, S I; Moyer, R A; Muller, S H; Pigarov, A Yu; Rosenberg, M; Smirnov, R D; West, W P; Boivin, R L; Bray, B D; Brooks, N H; Hyatt, A W; Wong, C P C; Roquemore, A L; Skinner, C H; Solomon, W M; Ratynskaia, S; Fenstermacher, M E; Groth, M; Lasnier, C J; McLean, A G; Stangeby, P C

2008-10-01

Dust production and accumulation present potential safety and operational issues for the ITER. Dust diagnostics can be divided into two groups: diagnostics of dust on surfaces and diagnostics of dust in plasma. Diagnostics from both groups are employed in contemporary tokamaks; new diagnostics suitable for ITER are also being developed and tested. Dust accumulation in ITER is likely to occur in hidden areas, e.g., between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In the DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering is able to resolve particles between 0.16 and 1.6 microm in diameter; using these data the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in two-dimension with a single camera or three-dimension using multiple cameras, but determination of particle size is challenging. In order to calibrate diagnostics and benchmark dust dynamics modeling, precharacterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase in carbon line (CI, CII, C(2) dimer) and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.

Reuyl Crater Dust Avalanches

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 13 May 2002) The Science The rugged, arcuate rim of the 90 km crater Reuyl dominates this THEMIS image. Reuyl crater is at the southern edge of a region known to be blanketed in thick dust based on its high albedo (brightness) and low thermal inertia values. This thick mantle of dust creates the appearance of snow covered mountains in the image. Like snow accumulation on Earth, Martian dust can become so thick that it eventually slides down the face of steep slopes, creating runaway avalanches of dust. In the center of this image about 1/3 of the way down is evidence of this phenomenon. A few dozen dark streaks can be seen on the bright, sunlit slopes of the crater rim. The narrow streaks extend downslope following the local topography in a manner very similar to snow avalanches on Earth. But unlike their terrestrial counterparts, no accumulation occurs at the bottom. The dust particles are so small that they are easily launched into the thin atmosphere where they remain suspended and ultimately blow away. The apparent darkness of the avalanche scars is due to the presence of relatively dark underlying material that becomes exposed following the passage of the avalanche. Over time, new dust deposition occurs, brightening the scars until they fade into the background. Although dark slope streaks had been observed in Viking mission images, a clear understanding of this dynamic phenomenon wasn't possible until the much higher resolution images from the Mars Global Surveyor MOC camera revealed the details. MOC images also showed that new avalanches have occurred during the time MGS has been in orbit. THEMIS images will allow additional mapping of their distribution and frequency, contributing new insights about Martian dust avalanches. The Story The stiff peaks in this image might remind you of the Alps here on Earth, but they really outline the choppy edge of a large Martian crater over 50 miles wide (seen in the context image at right). While these aren't the Alps, you will find quite a few avalanches. Avalanches of dust, however, not snow. Martian dust can become so thick in this area that it eventually slides down the steep slopes, creating runaway avalanches of dust. No dedicated, Swiss-like avalanche rescue teams would be needed much on Mars, however. Unlike snow, the dust doesn't pile up and accumulate at the bottom. Instead, dust particles are so small that they get launched into the atmosphere where they remain suspended until . . . poof! They are blown away and distributed lightly elsewhere. For evidence of past avalanches, check out the dark streaks running down the bright, sunlit slopes (western side of the peaks about 1/3 of the way down the image). These avalanche scars are dark because the underlying surface is not as bright as the removed dust. Eventually, new dust will settle over these scars, and the streaks will brighten until they fade into the background. The neat thing is that we'll be able to see all of these changes happening over time. Our current two Mars orbiters (called Mars Global Surveyor and 2001 Mars Odyssey) are showing that avalanche action is happening right now, all of the time on Mars. For example, the camera on Mars Global Surveyor has already taken pictures of the Martian surface in some areas that showed no avalanches - the first time the picture was snapped, that is. The next time around, the camera took a picture of the same area, only voila! New streaks, meaning new avalanches! That's why it can be so exciting to look at the Martian landscape over time to see how it changes. The THEMIS camera on Odyssey will continue to map out the places where the avalanches occur and how often. This information will really help scientists understand how dust is works to shape the terrain and to influence the Martian climate as it constantly swings into the atmosphere, falls down to the ground, and rises back up again. Stay tuned to see if you too can pick out the changes over time!

Dust Storm over the Red Sea

NASA Technical Reports Server (NTRS)

2002-01-01

In the summer months in the Northern Hemisphere, dust storms originating in the deserts around the Arabian Peninsula have a significant impact on the amount of solar radiation that reaches the surface. Winds sweep desert sands into the air and transport them eastward toward India and Asia with the seasonal monsoon. These airborne particles absorb and deflect incoming radiation and can produce a cooling effect as far away as North America. According to calculations performed by the NASA Goddard Institute for Space Studies (GISS), the terrain surrounding the southern portions of the Red Sea is one of the areas most dramatically cooled by the presence of summertime dust storms. That region is shown experiencing a dust storm in this true-color image from the Moderate Resolution Imaging Spectroradiometer (MODIS) acquired on July 11, 2002. The GISS model simulations indicate that between June and August, the temperatures would be as much as 2 degrees Celsius warmer than they are if it weren't for the dust in the air-a cooling equivalent to the passage of a rain cloud overhead. The image shows the African countries of Sudan (top left), Ethiopia (bottom left), with Eritrea nestled between them along the western coast of the Red Sea. Toward the right side of the image are Saudi Arabia (top) and Yemen (bottom) on the Arabian Peninsula. Overlooking the Red Sea, a long escarpment runs along the western edge of the Arabian Peninsula, and in this image appears to be blocking the full eastward expansion of the dust storm. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

Forensic-paternity effectiveness and genetics population analysis of six non-CODIS mini-STR loci (D1S1656, D2S441, D6S1043, D10S1248, D12S391, D22S1045) and SE33 in Mestizo and Amerindian populations from Mexico.

PubMed

Burguete-Argueta, Nelsi; Martínez De la Cruz, Braulio; Camacho-Mejorado, Rafael; Santana, Carla; Noris, Gino; López-Bayghen, Esther; Arellano-Galindo, José; Majluf-Cruz, Abraham; Antonio Meraz-Ríos, Marco; Gómez, Rocío

2016-11-01

STRs are powerful tools intensively used in forensic and kinship studies. In order to assess the effectiveness of non-CODIS genetic markers in forensic and paternity tests, the genetic composition of six mini short tandem repeats-mini-STRs-(D1S1656, D2S441, D6S1043, D10S1248, D12S391, D22S1045) and the microsatellite SE33 in Mestizo and Amerindian populations from Mexico were studied. Using multiplex polymerase chain reactions and capillary electrophoresis, this study genotyped all loci from 870 chromosomes and evaluated the statistical genetic parameters. All mini-STRs studied were in agreement with HW and linkage equilibrium; however, an important HW departure for SE33 was found in the Mestizo population (p ≤ 0.0001). Regarding paternity and forensic statistical parameters, high values of combined power discrimination and mean power of exclusion were found using these seven markers. The principal co-ordinate analysis based on allele frequencies of three mini-STRs showed the complex genetic architecture of the Mestizo population. The results indicate that this set of loci is suitable to genetically identify individuals in the Mexican population, supporting its effectiveness in human identification casework. In addition, these findings add new statistical values and emphasise the importance of the use of non-CODIS markers in complex populations in order to avoid erroneous assumptions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudakov, D. L.; Yu, J. H.; Boedo, J. A.

Dust production and accumulation present potential safety and operational issues for the ITER. Dust diagnostics can be divided into two groups: diagnostics of dust on surfaces and diagnostics of dust in plasma. Diagnostics from both groups are employed in contemporary tokamaks; new diagnostics suitable for ITER are also being developed and tested. Dust accumulation in ITER is likely to occur in hidden areas, e.g., between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In the DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers,more » visible imaging, and spectroscopy. Laser scattering is able to resolve particles between 0.16 and 1.6 {mu}m in diameter; using these data the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in two-dimension with a single camera or three-dimension using multiple cameras, but determination of particle size is challenging. In order to calibrate diagnostics and benchmark dust dynamics modeling, precharacterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase in carbon line (CI, CII, C{sub 2} dimer) and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.« less

HIRAS images of fossil dust shells around AGB stars

NASA Technical Reports Server (NTRS)

Waters, L. B. F. M.; Kester, Do J. M.; Bontekoe, Tj. Romke; Loup, C.

1994-01-01

We present high resolution HIRAS 60 and 100 micron images of AGB stars surrounded by fossil dust shells. Resolving the extended emission of the circumstellar dust allows a determination of the mass loss history of the star. We show that the geometry of the 60 micron emission surrounding HR 3126 agrees well with that of the optical reflection nebula. The emission around the carbon star U Hya is resolved into a central point source and a ring of dust, and the mass loss rate in the detached shell is 70 times higher than the current mass loss rate.

Image Analysis Based Estimates of Regolith Erosion Due to Plume Impingement Effects

NASA Technical Reports Server (NTRS)

Lane, John E.; Metzger, Philip T.

2014-01-01

Characterizing dust plumes on the moon's surface during a rocket landing is imperative to the success of future operations on the moon or any other celestial body with a dusty or soil surface (including cold surfaces covered by frozen gas ice crystals, such as the moons of the outer planets). The most practical method of characterizing the dust clouds is to analyze video or still camera images of the dust illuminated by the sun or on-board light sources (such as lasers). The method described below was used to characterize the dust plumes from the Apollo 12 landing.

Gone with the heat: a fundamental constraint on the imaging of dust and molecular gas in the early Universe

PubMed Central

Zhang, Zhi-Yu; Smith, M. W. L.; Xilouris, Emmanuel M.

2016-01-01

Images of dust continuum and carbon monoxide (CO) line emission are powerful tools for deducing structural characteristics of galaxies, such as disc sizes, H2 gas velocity fields and enclosed H2 and dynamical masses. We report on a fundamental constraint set by the cosmic microwave background (CMB) on the observed structural and dynamical characteristics of galaxies, as deduced from dust continuum and CO-line imaging at high redshifts. As the CMB temperature rises in the distant Universe, the ensuing thermal equilibrium between the CMB and the cold dust and H2 gas progressively erases all spatial and spectral contrasts between their brightness distributions and the CMB. For high-redshift galaxies, this strongly biases the recoverable H2 gas and dust mass distributions, scale lengths, gas velocity fields and dynamical mass estimates. This limitation is unique to millimetre/submillimetre wavelengths and unlike its known effect on the global dust continuum and molecular line emission of galaxies, it cannot be addressed simply. We nevertheless identify a unique signature of CMB-affected continuum brightness distributions, namely an increasing rather than diminishing contrast between such brightness distributions and the CMB when the cold dust in distant galaxies is imaged at frequencies beyond the Raleigh–Jeans limit. For the molecular gas tracers, the same effect makes the atomic carbon lines maintain a larger contrast than the CO lines against the CMB. PMID:27429763

Dust and Smoke

Atmospheric Science Data Center

2014-05-15

...     View Larger Image Desert dust particles tend to be larger in size than aerosols that originate ... for these two events. These MISR results distinguish desert dust, the most common non-spherical aerosol type, from pollution and ...

Characterization of Moving Dust Particles

NASA Technical Reports Server (NTRS)

Bos, Brent J.; Antonille, Scott R.; Memarsadeghi, Nargess

2010-01-01

A large depth-of-field Particle Image Velocimeter (PIV) has been developed at NASA GSFC to characterize dynamic dust environments on planetary surfaces. This instrument detects and senses lofted dust particles. We have been developing an autonomous image analysis algorithm architecture for the PIV instrument to greatly reduce the amount of data that it has to store and downlink. The algorithm analyzes PIV images and reduces the image information down to only the particle measurement data we are interested in receiving on the ground - typically reducing the amount of data to be handled by more than two orders of magnitude. We give a general description of PIV algorithms and describe only the algorithm for estimating the velocity of the traveling particles.

Dust Devil Tracks

NASA Image and Video Library

2017-03-06

This image captured by NASA 2001 Mars Odyssey spacecraft shows dust devil tracks in Aonia Terra. As the dust devil moves along the surface it scours the dust and fine materials away, revealing the darker rocky surface below the dust. Orbit Number: 66962 Latitude: -68.8221 Longitude: 241.346 Instrument: VIS Captured: 2017-01-17 13:13 http://photojournal.jpl.nasa.gov/catalog/PIA21501

Millimeter image of the HL Tau Disk: gaps opened by planets?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hui

2015-10-20

Several observed features which favor planet-induced gaps in the disk are pointed out. Parameters of a two-fluid simulation model are listed, and some model results are shown. It is concluded that (1) interaction between planets, gas, and dust can explain the main features in the ALMA observation; (2) the millimeter image of a disk is determined by the dust profile, which in turn is influenced by planetary masses, viscosity, disk self-gravity, etc.; and (3) models that focus on the complex physics between gas and dust (and planets) are crucial in interpreting the (sub)millimeter images of disks.

Using Engineering Cameras on Mars Landers and Rovers to Retrieve Atmospheric Dust Loading

NASA Astrophysics Data System (ADS)

Wolfe, C. A.; Lemmon, M. T.

2014-12-01

Dust in the Martian atmosphere influences energy deposition, dynamics, and the viability of solar powered exploration vehicles. The Viking, Pathfinder, Spirit, Opportunity, Phoenix, and Curiosity landers and rovers each included the ability to image the Sun with a science camera that included a neutral density filter. Direct images of the Sun provide the ability to measure extinction by dust and ice in the atmosphere. These observations have been used to characterize dust storms, to provide ground truth sites for orbiter-based global measurements of dust loading, and to help monitor solar panel performance. In the cost-constrained environment of Mars exploration, future missions may omit such cameras, as the solar-powered InSight mission has. We seek to provide a robust capability of determining atmospheric opacity from sky images taken with cameras that have not been designed for solar imaging, such as lander and rover engineering cameras. Operational use requires the ability to retrieve optical depth on a timescale useful to mission planning, and with an accuracy and precision sufficient to support both mission planning and validating orbital measurements. We will present a simulation-based assessment of imaging strategies and their error budgets, as well as a validation based on archival engineering camera data.

Martian Magnets Under the Microscope

NASA Technical Reports Server (NTRS)

2004-01-01

NASA's Mars Exploration Rover Spirit acquired this microscopic imager view of its capture magnet on sol 92 (April 6, 2004). Both Spirit and the Mars Exploration Rover Opportunity are equipped with a number of magnets. The capture magnet, as seen here, has a stronger charge than its sidekick, the filter magnet. The lower-powered filter magnet captures only the most magnetic airborne dust with the strongest charges, while the capture magnet picks up all magnetic airborne dust.

The magnets' primary purpose is to collect the martian magnetic dust so that scientists can analyze it with the rovers' Moessbauer spectrometers. While there is plenty of dust on the surface of Mars, it is difficult to confirm where it came from, and when it was last airborne. Because scientists are interested in learning about the properties of the dust in the atmosphere, they devised this dust-collection experiment.

The capture magnet is about 4.5 centimeters (1.8 inches) in diameter and is constructed with a central cylinder and three rings, each with alternating orientations of magnetization. Scientists have been monitoring the continual accumulation of dust since the beginning of the mission with panoramic camera and microscopic imager images. They had to wait until enough dust accumulated before they could get a Moessbauer spectrometer analysis. The results of that analysis, performed on sol 92, have not been sent back to Earth yet.

Parameterizing the Dust Around Herbig Ae/Be Stars: Multiwavelength Imaging, Radiative Transfer Modeling, and Near-Infrared Instrumentation

NASA Astrophysics Data System (ADS)

Doering, Ryan L.

2009-01-01

Determining Herbig Ae/Be star dust parameters provides constraints for planet formation theory, and yields information about the matter around intermediate-mass stars as they approach the main sequence. In this dissertation talk, I present the results of a multiwavelength imaging and radiative transfer modeling study of Herbig Ae/Be stars, and a near-infrared instrumentation project, with the aim of parameterizing the dust in these systems. The Hubble Space Telescope was used to search for optical light scattered by dust in a sample of young stars. This survey provided the first scattered-light image of the circumstellar environment around the Herbig Ae/Be star HD 97048. Structure is observed in the dust distribution similar to that seen in other Herbig Ae/Be systems. A ground-based near-infrared imaging study of Herbig Ae/Be candidates was also carried out. Photometry was collected for spectral energy distribution construction, and binary candidates were resolved. Detailed dust modeling of HD 97048 and HD 100546 was carried out with a two-component geometry consisting of a flared disk and an extended envelope. The models achieve a reasonable global fit to the spectral energy distributions, and produce images with the desired geometry. The disk midplane densities are found to go as r-0.5 and r-1.8, giving disk dust masses of 3.0 x 10-4 and 5.9 x 10-5 Msun for HD 97048 and HD 100546, respectively. A gas-to-dust mass ratio lower limit of 3.2 was calculated for HD 97048. Furthermore, I have participated in the development of the WIYN High Resolution Infrared Camera. The instrument operates in the near-infrared ( 0.8 - 2.5 microns), includes 13 filters, and has a pixel size of 0.1 arcsec, resulting in a field of view of 3 arcmin x 3 arcmin. An angular resolution of 0.25 arcsec is anticipated. I provide an overview of the instrument and report performance results.

Monitoring An Intensive Dust Event over Northern China Using Multi-satellite Observation

NASA Astrophysics Data System (ADS)

She, L.; Xue, Y.; Guang, J.; Mei, L.; Che, Y.; Fan, C.; Xie, Y.

2017-12-01

The deserts in western/northern China are one of the major mineral dust source regions of the world. Large amount of dust are emitted and blown east and southeast, especially in spring. An intensive dust event occurred over Northern China during May 3 - 8, 2017. The dust storms came from deserts in China and Mongolia. Due to the long-distance transport, more than ten provinces were affected by this dust event, several provinces occurred strong dust storm. In this study, multi-satellite data were employed to analyse the spatial-temporal evolution and dynamic transport behaviour of the dust plume, especially the geostationary satellite data - Himawari8 Advanced Himawari Imager (AHI) data. AHI data was used to estimate hourly Aerosol Optical Depth (AOD) to monitoring the aerosol distribution as well as the dust plume movements, as the dust storms often characterized by high AOD. A simple dust index was also calculated based on AHI VIS and TIR data to estimate the dust intensity. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data and the Ozone Monitoring Instrument (OMI) Aerosol Index were used as additional data sources to monitor the dust vertical distribution and provide independent information of dust presence. MODIS aerosol product and AERONET aerosol measurements were compared with the AHI retrieved AODs, the comparisons show a good agreement. The dust index was compared with the ground measurements as well as the corresponding RGB image. Simulations from HYSPLIT back-trajectory analysis shows similar temporal variation with the calculated AOD and dust index of the dust plume. Those comparisons with other satellite products and ground measurements suggested both the calculated AOD and dust index well depicted the dust events compared.

Middle East Health and Air Quality Utilizing NASA EOS in the Saharan and Arabian Deserts to Examine Dust Particle Size and Mineralogy of Aerosols

NASA Technical Reports Server (NTRS)

Keeton, Tiffany; Barrick, Bradley; Cooksey, Kirstin; Cowart, Kevin; Florence, Victoria; Herdy, Claire; Padgett-Vasquez, Steve; Luvall, Jeffrey; Molthan, Andrew

2012-01-01

Ground-based studies conducted in Iraq have revealed the presence of potential human pathogens in airborne dust. According to the Environmental Protection Agency (EPA), airborne particulate matter below 2.5micron (PM2.5) can cause long-term damage to the human respiratory system. NASA fs Earth Observing System (EOS) can be used to determine spectral characteristics of dust particles and dust particle sizes. Comparing dust particle size from the Sahara and Arabian Deserts gives insight into the composition and atmospheric transport characteristics of dust from each desert. With the use of NASA SeaWiFS DeepBlue Aerosol, dust particle sizes were estimated using Angstrom Exponent. Brightness Temperature Difference (BTD) equation was used to determine the area of the dust storm. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra satellite was utilized in calculating BTD. Mineral composition of a dust storm that occurred 17 April 2008 near Baghdad was determined using imaging spectrometer data from the JPL Spectral Library and EO-1 Hyperion data. Mineralogy of this dust storm was subsequently compared to that of a dust storm that occurred over the Bodele Depression in the Sahara Desert on 7 June 2003.

Global Albedo Variations on Mars from Recent MRO/MARCI and Other Space-Based Observations

NASA Astrophysics Data System (ADS)

Bell, J. F., III; Wellington, D. F.

2017-12-01

Dramatic changes in Mars surface albedo have been quantified by telescopic, orbital, and surface-based observations over the last 40 years. These changes provide important inputs for global and mesoscale climate models, enabling characterization of seasonal and secular variations in the distribution of mobile surface materials (dust, sand) in the planet's current climate regime. Much of the modern record of dust storms and albedo changes comes from synoptic-scale global imaging from the Viking Orbiter, Mars Global Surveyor (MGS), Hubble Space Telescope (HST), and Mars Reconnaissance Orbiter (MRO) missions, as well as local-scale observations from long-lived surface platforms like the Spirit and Opportunity rovers. Here we focus on the substantial time history of global-scale images acquired from the MRO Mars Color Imager (MARCI). MARCI is a wide-angle multispectral imager that acquires daily coverage of most of the surface at up to 1 km/pixel. MARCI has been in orbit since 2006, providing six Mars years of continuous surface and atmospheric observations, and building on the nearly five previous Mars years of global-scale imaging from the MGS Mars Orbiter Camera Wide Angle (MOC/WA) imager, which operated from 1997 to 2006. While many of the most significant MARCI-observed changes in the surface albedo are the result of large dust storms, other regions experience seasonal darkening events that repeat with different degrees of annual regularity. Some of these are associated with local dust storms, while for others, frequent surface changes take place with no associated evidence for dust storms, suggesting action by seasonally-variable winds and/or small-scale storms/dust devils too small to resolve. Discrete areas of dramatic surface changes across widely separated regions of Tharsis and in portions of Solis Lacus and Syrtis Major are among the regions where surface changes have been observed without a direct association to specific detectable dust storm events. Deposition following the annual southern summer dusty season plays a significant role in maintaining the cyclic nature of these changes. These and other historical observations also show that major regional or global-scale dust storms produce unique changes that may require several Mars years to reverse.

Martian Dust Devil Movie, Phoenix Sol 104

NASA Technical Reports Server (NTRS)

2008-01-01

The Surface Stereo Imager on NASA's Phoenix Mars Lander caught this dust devil in action west of the lander in four frames shot about 50 seconds apart from each other between 11:53 a.m. and 11:56 a.m. local Mars time on Sol 104, or the 104th Martian day of the mission, Sept. 9, 2008.

Dust devils have not been detected in any Phoenix images from earlier in the mission, but at least six were observed in a dozen images taken on Sol 104.

Dust devils are whirlwinds that often occur when the Sun heats the surface of Mars, or some areas on Earth. The warmed surface heats the layer of atmosphere closest to it, and the warm air rises in a whirling motion, stirring dust up from the surface like a miniature tornado.

The dust devil visible in this sequence was about 1,000 meters (about 3,300 feet) from the lander when the first frame was taken, and had moved to about 1,700 meters (about 5,600 feet) away by the time the last frame was taken about two and a half minutes later. The dust devil was moving westward at an estimated speed of 5 meters per second (11 miles per hour), which is similar to typical late-morning wind speed and direction indicated by the telltale wind gauge on Phoenix.

This dust devil is about 5 meters (16 feet) in diameter. This is much smaller than dust devils that have been observed by NASA's Mars Exploration Rover Spirit much closer to the equator. It is closer in size to dust devils seen from orbit in the Phoenix landing region, though still smaller than those..

The image has been enhanced to make the dust devil easier to see. Some of the frame-to-frame differences in the appearance of foreground rocks is because each frame was taken through a different color filter.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

SPITZER SEARCH FOR DUST DISKS AROUND CENTRAL STARS OF PLANETARY NEBULAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bilikova, Jana; Chu Youhua; Gruendl, Robert A.

2012-05-01

Two types of dust disks have been discovered around white dwarfs (WDs): small dust disks within the Roche limits of their WDs and large dust disks around hot WDs extending to radial distances of 10-10{sup 2} AU. The majority of the latter WDs are central stars of planetary nebulae (CSPNs). We have therefore used archival Spitzer Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) observations of PNs to search for CSPNs with IR excesses and to make a comparative investigation of dust disks around stars at different evolutionary stages. We have examined available images of 72 resolvedmore » PNs in the Spitzer archive and found 56 of them large enough for the CSPN to be resolved from the PN. Among these, only 42 CSPNs are visible in IRAC and/or MIPS images and selected for photometric measurements. From the spectral energy distributions (SEDs) of these CSPNs, we find 19 cases with clear IR excess. Of these, seven are [WC]-type stars, two have apparent visual companions that account for the observed excess emission, two are symbiotic CSPNs, and in eight cases the IR excess originates from an extended emitter, likely a dust disk. For some of these CSPNs, we have acquired follow-up Spitzer MIPS images, Infrared Spectrograph spectra, and Gemini NIRI and Michelle spectroscopic observations. The SEDs and spectra show a great diversity in the emission characteristics of the IR excesses, which may imply different mechanisms responsible for the excess emission. For CSPNs whose IR excesses originate from dust continuum, the most likely dust production mechanisms are (1) breakup of bodies in planetesimal belts through collisions and (2) formation of circumstellar dust disks through binary interactions. A better understanding of post-asymptotic giant branch binary evolution as well as debris disk evolution along with its parent star is needed to distinguish between these different origins. Future observations to better establish the physical parameters of the dust disks and the presence of companions are needed for models to discern between the possible dust production mechanisms.« less

Pixel-based dust-extinction mapping in nearby galaxies: A new approach to lifting the veil of dust

NASA Astrophysics Data System (ADS)

Tamura, Kazuyuki

In the first part of this dissertation, I explore a new approach to mapping dust extinction in galaxies, using the observed and estimated dust-free flux- ratios of optical V -band and mid-IR 3.6 micro-meter emission. Inferred missing V -band flux is then converted into an estimate of dust extinction. While dust features are not clearly evident in the observed ground-based images of NGC 0959, the target of my pilot study, the dust-map created with this method clearly traces the distribution of dust seen in higher resolution Hubble images. Stellar populations are then analyzed through various pixel Color- Magnitude Diagrams and pixel Color-Color Diagrams (pCCDs), both before and after extinction correction. The ( B - 3.6 microns) versus (far-UV - U ) pCCD proves particularly powerful to distinguish pixels that are dominated by different types of or mixtures of stellar populations. Mapping these pixel- groups onto a pixel-coordinate map shows that they are not distributed randomly, but follow genuine galactic structures, such as a previously unrecognized bar. I show that selecting pixel-groups is not meaningful when using uncorrected colors, and that pixel-based extinction correction is crucial to reveal the true spatial variations in stellar populations. This method is then applied to a sample of late-type galaxies to study the distribution of dust and stellar population as a function of their morphological type and absolute magnitude. In each galaxy, I find that dust extinction is not simply decreasing radially, but that is concentrated in localized clumps throughout a galaxy. I also find some cases where star-formation regions are not associated with dust. In the second part, I describe the application of astronomical image analysis tools for medical purposes. In particular, Source Extractor is used to detect nerve fibers in the basement membrane images of human skin-biopsies of obese subjects. While more development and testing is necessary for this kind of work, I show that computerized detection methods significantly increase the repeatability and reliability of the results. A patent on this work is pending.

A New Dusts Sensor for Cultural Heritage Applications Based on Image Processing

PubMed Central

Proietti, Andrea; Leccese, Fabio; Caciotta, Maurizio; Morresi, Fabio; Santamaria, Ulderico; Malomo, Carmela

2014-01-01

In this paper, we propose a new sensor for the detection and analysis of dusts (seen as powders and fibers) in indoor environments, especially designed for applications in the field of Cultural Heritage or in other contexts where the presence of dust requires special care (surgery, clean rooms, etc.). The presented system relies on image processing techniques (enhancement, noise reduction, segmentation, metrics analysis) and it allows obtaining both qualitative and quantitative information on the accumulation of dust. This information aims to identify the geometric and topological features of the elements of the deposit. The curators can use this information in order to design suitable prevention and maintenance actions for objects and environments. The sensor consists of simple and relatively cheap tools, based on a high-resolution image acquisition system, a preprocessing software to improve the captured image and an analysis algorithm for the feature extraction and the classification of the elements of the dust deposit. We carried out some tests in order to validate the system operation. These tests were performed within the Sistine Chapel in the Vatican Museums, showing the good performance of the proposed sensor in terms of execution time and classification accuracy. PMID:24901977

Dust Devil Tracks

NASA Image and Video Library

2017-02-20

Today's VIS image shows dust devil tracks on the plains of Aonia Terra. As the dust devil moves across the surface it scours the fine dust particles, revealing the darker rock surface below. Orbit Number: 66800 Latitude: -65.2605 Longitude: 239.338 Instrument: VIS Captured: 2017-01-04 04:52 http://photojournal.jpl.nasa.gov/catalog/PIA21316

Dust Streams from Tunisia

NASA Technical Reports Server (NTRS)

2002-01-01

On October 6, 2001, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) captured this true-color image of a large dust storm blowing northeastward across the Mediterranean Sea from Tunisia. According to Joseph Prospero, professor of atmospheric science at the University of Miami, there is an unusual arc-shaped 'front' to the dust cloud. The storm's shape suggests that the source of the dust is rather small and that the meteorology driving it rather unusual. The dust seems to be coming out of the wadis, dry lakebeds and riverbeds, at the base of the Tell Atlas Mountains in northern Tunisia and eastern Algeria. The dust appears to be blowing toward the island of Sicily, Italy (toward the upper righthand corner). Also notice there is a relatively thin plume of smoke emanating eastward from the top of Mount Etna on Sicily. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

Featured Image: Making Dust in the Lab

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-12-01

This remarkable photograph (which spans only 10 m across; click for a full view) reveals what happens when you form dust grains in a laboratory under conditions similar to those of interstellar space. The cosmic life cycle of dust grains is not well understood we know that in the interstellar medium (ISM), dust is destroyed at a higher rate than it is produced by stellar sources. Since the amount of dust in the ISM stays constant, however, there must be additional sources of dust production besides stars. A team of scientists led by Daniele Fulvio (Pontifical Catholic University of Rio de Janeiro and the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena) have now studied formation mechanisms of dust grains in the lab by mimicking low-temperature ISM conditions and exploring how, under these conditions, carbonaceous materials condense from gas phase to form dust grains. To read more about their results and see additional images, check out the paper below.CitationDaniele Fulvio et al 2017 ApJS 233 14. doi:10.3847/1538-4365/aa9224

The Dust Ring of Luminous Blue Variable Candidate HD 168625: Infrared Observations and Model Calculations

NASA Astrophysics Data System (ADS)

O'Hara, Timothy B.; Meixner, Margaret; Speck, Angela K.; Ueta, Toshiya; Bobrowsky, Matthew

2003-12-01

We present a 2.218 μm image from the Hubble Space Telescope/Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and a 55 μm image from ISOPHOT of the dust ring surrounding the luminous blue variable (LBV) candidate HD 168625, together with new temperature and optical depth maps derived from mid-IR images. The shell is detached from the star in the near-IR, and substructure in the overall toroidal shell is visible. The far-IR image constrains the extent of the dust shell to ~25" in diameter, providing an upper radius limit for modeling. The temperature maps and the NICMOS image show evidence for very small transiently heated dust grains in the shell. The opacity maps show higher optical depth in the limbs, consistent with interpretation of the dust shell as an equatorially enhanced torus inclined ~60° with respect to the observer. An overall trend in the dust emission location with wavelength is observed and interpreted as a variation with respect to location in the nebula of either the dust grain size distribution or gas-to-dust mass ratio. Radiative transfer calculations using 2-DUST indicate that a mass-loss event occurred ~5700 yr ago with a rate of (1.9+/-0.1)×10-4Msolaryr-1, creating a dust torus that currently has a τV~0.22 in the equatorial plane and a dust mass of (2.5+/-0.1)×10-3Msolar. Using published values for the gas mass, we find a gas-to-dust mass ratio of 840, which is ~4 times higher than current estimates for the interstellar medium. In addition to a high equator-to-pole density ratio (~31) torus, an elliptical midshell is needed to reproduce the appearance and spectral energy distribution of the dust. Therefore, HD 168625 is an excellent example of proposed models of LBV nebulae in which a stellar wind interacts with a preexisting density contrast and creates a blowout in the polar direction perpendicular to the equatorial ring. The circumstellar shell is much lower in mass than that of LBV η Carinae, suggesting that HD 168625 had a lower mass progenitor. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555 these observations are associated with proposal 7898. Based also on observations with ISO, an ESA project with instruments funded by ESA member states (especially the PI countries: France, Germany, the Netherlands, and the United Kingdom) and with the participation of ISAS and NASA.

Zeta Ophiuchi -- Runaway Star Plowing through Space Dust

NASA Image and Video Library

2011-01-24

The blue star near the center of this image is Zeta Ophiuchi. Zeta Ophiuchi is actually a very massive, hot, bright blue star plowing its way through a large cloud of interstellar dust and gas in this image from NASA Wide-field Infrared Survey Explorer.

DIRBE obtained at infrared wavelengths of 25, 60 and 100 Aum

NASA Technical Reports Server (NTRS)

2002-01-01

This image combines data from the DIRBE obtained at infrared wavelengths of 25, 60 and 100 Aum. The sky brightness at these wavelengths is represented respectively by blue, green, and red colors in the image. The plane of the Milky Way Galaxy lies horizontally across the middle of the image with the Galactic center at the center. The image is dominated by the thermal emission from interstellar dust in the Milky Way. The wispy-looking dust features are called 'infrared cirrus.' The structured, warmer emission from interplanetary dust, shown in blue, is also prominent. The image shows a number of well-known dusty regions in the Milky Way, such as the Orion molecular clouds (below the plane, far right) which are active 'stellar nurseries' in our Galaxy. Two neighboring galaxies, the Large and Small Magellanic Clouds also can be distinguished (below the plane, approximately halfway between the center and right edge of the image).

Dust transport and deposition observed from the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Kaufman, Y. J.; Koren, I.; Remer, L. A.; Tanré, D.; Ginoux, P.; Fan, S.

2005-05-01

Meteorological observations, in situ data, and satellite images of dust episodes were used already in the 1970s to estimate that 100 Tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and are deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but it deteriorates air quality, as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport, and deposition. The Terra spacecraft, launched at the dawn of the last millennium, provides the first systematic well-calibrated multispectral measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and to evaluate the African dust column concentration, transport, and deposition. We found that 240 ± 80 Tg of dust are transported annually from Africa to the Atlantic Ocean, 140 ± 40 Tg are deposited in the Atlantic Ocean, 50 Tg fertilize the Amazon Basin (four times as previous estimates, thus explaining a paradox regarding the source of nutrition to the Amazon forest), 50 Tg reach the Caribbean, and 20 Tg return to Africa and Europe. The results are compared favorably with dust transport models for maximum particle diameter between 6 and 12 μm. This study is a first example of quantitative use of MODIS aerosol for a geophysical research.

THEMIS VIS and IR observations of a high-altitude Martian dust devil

USGS Publications Warehouse

Cushing, G.E.; Titus, T.N.; Christensen, P.R.

2005-01-01

The Mars Odyssey Thermal Emission Imaging System (THEMIS) imaged a Martian dust devil in both visible and thermal-infrared wavelengths on January 30, 2004. We believe this is the first documented infrared observation of an extraterrestrial dust devil, and the highest to be directly observed at more than 16 kilometers above the equatorial geoid of Mars. This dust devil measured over 700 meters in height and 375 meters across, and the strongest infrared signature was given by atmospheric dust absorption in the 9-micron range (THEMIS IR band 5). In addition to having formed in the extremely low-pressure environment of about 1 millibar, this dust devil is of particular interest because it was observed at 16:06 local time. This is an unusually late time of day to find dust devils on Mars, during a period when rapid surface cooling typically reduces the boundary-layer turbulence necessary to form these convective vortices. Understanding the mechanisms for dust-devil formation under such extreme circumstances will help to constrain theories of atmospheric dynamics, and of dust lifting and transport mechanisms on Mars. Copyright 2005 by the American Geophysical Union.

Spirit Captures Two Dust Devils On the Move

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Figure 1 Annotated

At the Gusev site recently, skies have been very dusty, and on its 421st sol (March 10, 2005) NASA's Mars Exploration Rover Spirit spied two dust devils in action. This is an image from the rover's navigation camera.

Views of the Gusev landing region from orbit show many dark streaks across the landscape -- tracks where dust devils have removed surface dust to show relatively darker soil below -- but this is the first time Spirit has photographed an active dust devil.

Scientists are considering several causes of these small phenomena. Dust devils often occur when the Sun heats the surface of Mars. Warmed soil and rocks heat the layer of atmosphere closest to the surface, and the warm air rises in a whirling motion, stirring dust up from the surface like a miniature tornado. Another possibility is that a flow structure might develop over craters as wind speeds increase. As winds pick up, turbulence eddies and rotating columns of air form. As these columns grow in diameter they become taller and gain rotational speed. Eventually they become self-sustaining and the wind blows them down range.

One sol before this image was taken, power output from Spirit's solar panels went up by about 50 percent when the amount of dust on the panels decreased. Was this a coincidence, or did a helpful dust devil pass over Spirit and lift off some of the dust?

By comparing the separate images from the rover's different cameras, team members estimate that the dust devils moved about 500 meters (1,640 feet) in the 155 seconds between the navigation camera and hazard-avoidance camera frames; that equates to about 3 meters per second (7 miles per hour). The dust devils appear to be about 1,100 meters (almost three-quarters of a mile) from the rover.

Dust Devils Seen by Spirit

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Figure 1 Annotated

At the Gusev site recently, skies have been very dusty, and on its 421st sol (March 10, 2005) NASA's Mars Exploration Rover Spirit spied two dust devils in action. This pair of images is from the rover's rear hazard-avoidance camera. Views of the Gusev landing region from orbit show many dark streaks across the landscape -- tracks where dust devils have removed surface dust to show relatively darker soil below -- but this is the first time Spirit has photographed an active dust devil.

Scientists are considering several causes of these small phenomena. Dust devils often occur when the Sun heats the surface of Mars. Warmed soil and rocks heat the layer of atmosphere closest to the surface, and the warm air rises in a whirling motion, stirring dust up from the surface like a miniature tornado. Another possibility is that a flow structure might develop over craters as wind speeds increase. As winds pick up, turbulence eddies and rotating columns of air form. As these columns grow in diameter they become taller and gain rotational speed. Eventually they become self-sustaining and the wind blows them down range.

One sol before this image was taken, power output from Spirit's solar panels went up by about 50 percent when the amount of dust on the panels decreased. Was this a coincidence, or did a helpful dust devil pass over Spirit and lift off some of the dust?

By comparing the separate images from the rover's different cameras, team members estimate that the dust devils moved about 500 meters (1,640 feet) in the 155 seconds between the navigation camera and hazard-avoidance camera frames; that equates to about 3 meters per second (7 miles per hour). The dust devils appear to be about 1,100 meters (almost three-quarters of a mile) from the rover.

Chalk dustfall during classroom teaching: particle size distribution and morphological characteristics.

PubMed

Majumdar, Deepanjan; William, S P M Prince

2009-01-01

The study was undertaken to examine the nature of particulate chalk dust settled on classroom floor during traditional teaching with dusting and non-dusting chalks on two types of boards viz. rough and smooth. Settling chalk particles were collected for 30 min during teaching in glass Petri plates placed in classrooms within 3 m distance from the teaching boards. Particle size distribution, scanning electron microscopic images of chalk dusts and compressive strength of two types of chalks were tested and evaluated. Results showed that a larger proportion of dusts generated from anti-dusting chalks were of <4.5 and <2.5 microm size on both smooth and rough boards, as compared to dusting chalks. Non-dusting chalks, on an average, produced about 56% and 62% (by volume) of <4.5 microm (respirable) diameter, on rough and smooth boards, respectively, while the corresponding values for dusting chalks were 36% and 45%. Also, on an average, 83% and 94% (by volume) of the particles were <11 microm (thoracic) in case of non-dusting chalks against 61% and 72% for dusting chalks on rough and smooth boards, respectively. Interestingly, taking into account the mass of chalk dust produced per unit time, which was higher in dusting chalks than non dusting chalks, the former was actually producing higher amount of PM <4.5 and <11 particles from both types of boards. Scanning electron microscope images revealed that chalk particles had random shape, although in dusting chalks prevalence of elongated particles was observed, apparently due to the longitudinal breaking of the chalks during writing, which was confirmed during compressive strength testing. We could conclude that dusting chalks could be potentially more harmful than anti dusting chalks, as they produced higher amount of potentially dangerous PM 4.5 and PM 11.

Airborne Sea of Dust over China

NASA Technical Reports Server (NTRS)

2002-01-01

TDust covered northern China in the last week of March during some of the worst dust storms to hit the region in a decade. The dust obscuring China's Inner Mongolian and Shanxi Provinces on March 24, 2002, is compared with a relatively clear day (October 31, 2001) in these images from the Multi-angle Imaging SpectroRadiometer's vertical-viewing (nadir) camera aboard NASA's Terra satellite. Each image represents an area of about 380 by 630 kilometers (236 by 391 miles). In the image from late March, shown on the right, wave patterns in the yellowish cloud liken the storm to an airborne ocean of dust. The veil of particulates obscures features on the surface north of the Yellow River (visible in the lower left). The area shown lies near the edge of the Gobi desert, a few hundred kilometers, or miles, west of Beijing. Dust originates from the desert and travels east across northern China toward the Pacific Ocean. For especially severe storms, fine particles can travel as far as North America. The Multi-angle Imaging SpectroRadiometer, built and managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., is one of five Earth-observing instruments aboard the Terra satellite, launched in December 1999. The instrument acquires images of Earth at nine angles simultaneously, using nine separate cameras pointed forward, downward and backward along its flight path. The change in reflection at different view angles affords the means to distinguish different types of atmospheric particles, cloud forms and land surface covers. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team

China Dust

Atmospheric Science Data Center

2013-04-16

... SpectroRadiometer (MISR) nadir-camera images of eastern China compare a somewhat hazy summer view from July 9, 2000 (left) with a ... arid and sparsely vegetated surfaces of Mongolia and western China pick up large quantities of yellow dust. Airborne dust clouds from the ...

Dust Devil Track Occurrence in Argyre Planitia.

NASA Astrophysics Data System (ADS)

Whelley, P. L.; Balme, M. R.; Greeley, R.

2002-12-01

Martian dust devil tracks were first observed in Viking Orbiter images [Thomas et al., 1985]. While the interpretation of these features was at first controversial, it is now widely accepted that the tracks are formed by the passage of small convective vortices (dust devils). As the dust devils travel across the surface the atmosphere is loaded with fine particles creating a visible trail inferred to be removal or deposition of material [Greeley et al., 2001]. Mars Global Surveyor (MGS) Mars Orbital Camera (MOC) images of dust devil tracks in Argyre Planitia were used to asses dust devil track abundance as a function of Martian season as well as elevation using Mars Orbiter Laser Altimeter (MOLA) data. Argyre Planitia is a large impact basin in the southern hemisphere (55° to 33°W and 35° to 58°S), with topographic relief of 7 km with the median at -1km. We have studied the 564 Narrow Angle MOC images (taken as of summer 2002) covering the area. The images were divided into two categories: those with devil tracks and those without. The Ls (solar longitude degrees as a fraction of orbit) and elevation of all of the images with and without devil tracks were noted. The elevation was recorded at the center point of each MOC image using MOLA data. A polar plot of all of the images shows a statistically random distribution throughout the Martian year. A context map of the images shows a representative distribution over the area of the crater itself. A polar plot of dust devil track occurrence within the area observed shows a major concentration of tracks between Ls 200° and 360° (southern spring to late summer). A seasonal breakdown of devil track occurrence as a percentage of total area observed yields: fall 11.25%, winter 2.24%, spring 27.21%, and summer 46.49%. We therefore conclude that dust devils tracks are formed preferentially in summer and are destroyed, fade or are covered, over a period of a few months. The elevation of all 564 images was measured and 1km bins were used to calculate the percent of occurrence. We discovered that, at 3km 0% of the observed area contain dust devil tracks, 2km 7.69%, 1km 12.90%, at Datum 15.95%, -1km 8.97%, -2km 28.92%, -3km% 50.00%, -4km 50.00%. Independent of the season a majority of the devil tracks were observed below -3km. Therefore elevation is a key factor governing the formation of dust devils or their ability to produce tracks. Our interpretation of these results is that dust devils are much more likely to form during the summer and, as suggested by recent experiments [Balme et al., 2002], that they are more efficient at moving materials on the surface in areas where the atmospheric pressure is greatest (in the lowest elevations). The short timescale for disappearance of tracks suggests that the distinct albedo variations of the tracks result from only the removal or deposition of a very thin layer of material. Thomas. P. et al., 1985, Science v. 230 Greeley. R. et al., 2001, LPSC XXXII Balme. M. et al., 2002, LPSC XXXIII

Slope Streaks on a Dusty Planet

NASA Image and Video Library

2015-05-06

Mars is a dusty place and in some locations thick blankets of its characteristically red dust can slowly settle out of the atmosphere and accumulate on slopes. This dust is also a lot brighter than the dust-free terrain on Mars; so, if you scrape off the dust, you'll see a darker surface underneath. This particular image shows one of these dusty areas. The dark streaks on the slopes are locations where the dust has slumped downhill revealing a less dusty surface underneath. In some cases, these slope streaks might be triggered by Marsquakes or nearby meteorite impacts. Scientists think they form quickly: more like an avalanche than dust slowly creeping downhill. Look more closely and you'll notice that some streaks are darker than others. Dust is settling out of the atmosphere all the time and these dark streaks get slowly buried by fresh dust so that they fade back into their brighter redder surroundings. It's not certain how long this fading takes to happen, but it's probably close to a few decades. Dust is an important player in the weather and climate on Mars. Images like this are used to monitor slow changes in these streaks over time to better understand how much dust is settling on the surface. http://photojournal.jpl.nasa.gov/catalog/PIA19456

Case study of dust event sources from the Gobi and Taklamakan deserts: An investigation of the horizontal evolution and topographical effect using numerical modeling and remote sensing.

PubMed

Fan, Jin; Yue, Xiaoying; Sun, Qinghua; Wang, Shigong

2017-06-01

A severe dust event occurred from April 23 to April 27, 2014, in East Asia. A state-of-the-art online atmospheric chemistry model, WRF/Chem, was combined with a dust model, GOCART, to better understand the entire process of this event. The natural color images and aerosol optical depth (AOD) over the dust source region are derived from datasets of moderate resolution imaging spectroradiometer (MODIS) loaded on a NASA Aqua satellite to trace the dust variation and to verify the model results. Several meteorological conditions, such as pressure, temperature, wind vectors and relative humidity, are used to analyze meteorological dynamic. The results suggest that the dust emission occurred only on April 23 and 24, although this event lasted for 5days. The Gobi Desert was the main source for this event, and the Taklamakan Desert played no important role. This study also suggested that the landform of the source region could remarkably interfere with a dust event. The Tarim Basin has a topographical effect as a "dust reservoir" and can store unsettled dust, which can be released again as a second source, making a dust event longer and heavier. Copyright © 2016. Published by Elsevier B.V.

Cometary dust at the nanometre scale - the MIDAS view after perihelion

NASA Astrophysics Data System (ADS)

Bentley, M. S.; Torkar, K.; Jeszenszky, H.; Romstedt, J.; Schmied, R.; Mannel, T.

2015-10-01

The MIDAS instrument on-board the Rosetta orbiter [1] is a unique combination of a dust collection and handling system and a high resolution Atomic Force Microscope (AFM). By building three-dimensional images of the dust particle topography with nano- to micrometre resolution, MIDAS addresses a range of fundamental questions in Solar System and cometary sciences. The greatest number of particles is expected to be collected around perihelion and the initial results of imaging these will be presented.

Staphylococcus aureus hyaluronidase is a CodY-regulated virulence factor.

PubMed

Ibberson, Carolyn B; Jones, Crystal L; Singh, Shweta; Wise, Matthew C; Hart, Mark E; Zurawski, Daniel V; Horswill, Alexander R

2014-10-01

Staphylococcus aureus is a Gram-positive pathogen that causes a diverse range of bacterial infections. Invasive S. aureus strains secrete an extensive arsenal of hemolysins, immunomodulators, and exoenzymes to cause disease. Our studies have focused on the secreted enzyme hyaluronidase (HysA), which cleaves the hyaluronic acid polymer at the β-1,4 glycosidic bond. In the study described in this report, we have investigated the regulation and contribution of this enzyme to S. aureus pathogenesis. Using the Nebraska Transposon Mutant Library (NTML), we identified eight insertions that modulate extracellular levels of HysA activity. Insertions in the sigB operon, as well as in genes encoding the global regulators SarA and CodY, significantly increased HysA protein levels and activity. By altering the availability of branched-chain amino acids, we further demonstrated CodY-dependent repression of HysA activity. Additionally, through mutation of the CodY binding box upstream of hysA, the repression of HysA production was lost, suggesting that CodY is a direct repressor of hysA expression. To determine whether HysA is a virulence factor, a ΔhysA mutant of a community-associated methicillin-resistant S. aureus (CA-MRSA) USA300 strain was constructed and found to be attenuated in a neutropenic, murine model of pulmonary infection. Mice infected with this mutant strain exhibited a 4-log-unit reduction in bacterial burden in their lungs, as well as reduced lung pathology and increased levels of pulmonary hyaluronic acid, compared to mice infected with the wild-type, parent strain. Taken together, these results indicate that S. aureus hyaluronidase is a CodY-regulated virulence factor. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Investigation of dust formations in the atmosphere on the basis of satellite observations

NASA Astrophysics Data System (ADS)

Ivanchik, M. V.; Kliushnikov, S. I.; Krovotyntsev, V. A.; Serebrennikov, A. N.

1984-06-01

A method for the computer processing of space photographs is described which makes it possible to determine dust formations in the atmosphere. Dust formations are identified according to the character of contrast-density distribution. Processed images are compared with actinometric data collected in a dust storm area (Conakry, Guinea, May 1983).

Dust loading in Gusev crater, Mars: Results from two active dust devil seasons

NASA Astrophysics Data System (ADS)

Waller, D. A.; Greeley, R.; Neakrase, L. D.; Landis, G. A.; Whelley, P.; Thompson, S. D.

2009-12-01

Dust devils dominate the volcanic plains at the Mars Exploration Rover (MER) landing site within the Low Albedo Zone (LAZ) in Gusev Crater. Previous studies indicate that the inferred pressure drop within the dust devil core allows the vortex to lift large amounts of unconsolidated dust high into the atmosphere which contributes to the atmospheric haze. Previous laboratory results indicate that dust devils are efficient in lifting very fine-grained (<10 μm) material, even when boundary layer winds do not exceed previously predicted threshold wind speeds (~30-35 m/s at 1.5 m above the surface for Mars conditions). Since landing in Gusev crater in January 2004, MER Spirit has obtained data for two dust devil seasons (defined as the period of time when the first and last dust devils were imaged), with a third season currently being analyzed. These seasons typically correspond to southern spring and summer, when winds capable of lifting sediment are determined to be most frequent. All observations for Season One were taken as Spirit neared the summit of Husband Hill. During Season Two Spirit imaged dust devils in the plains as it traversed within the Inner Basin, a low-lying area in the Columbia Hills complex. All results were extrapolated so that they are representative of the entire LAZ. Season One lasted 270 sols (March 2005 to December 2005 corresponding to Ls 173.2 to 339.5 degrees), whereas Season Two lasted 153 sols (January 2007 to June 2007 corresponding to Ls 171.2 to 266.7 degrees) and ended suddenly on sol 1240 just after the dust devil frequency peaked for the season. This abrupt drop in dust devil activity corresponded to atmospheric opacity levels that exceeded 1.0 and the onset of a global dust storm that originated in the southern hemisphere that engulfed Gusev within weeks. Results show a large contrast in activity between the two seasons. An 81% decrease in dust devil frequency across the plains was found in Season Two. 533 dust devils were imaged during Season One and resulted in an average of ~50 active dust devils/km2/sol extrapolated out to the LAZ while 103 dust devils were imaged during Season Two resulting in an average of ~5 active dust devils/km2/sol within the LAZ. This drop in dust devil frequency from one season to the next was coupled with a 50% decrease in the amount of dust loaded into the atmosphere during Season Two (~19 kg/km2/sol in Season One and ~10 kg/km2/sol in Season Two). Previous models indicate that the increased amount of dust in the atmosphere during the storm decreased the amount of solar insolation to the surface therefore also decreasing the surface heat flux. The rapidly decreasing surficial heat flux prevents the temperature lapse rate (change in temperature gradient with elevation) from becoming super-adiabatic and therefore causes the low-altitude atmospheric temperature profile to become too homogeneous to sustain convective plumes.

A new false color composite technique for dust enhancement and point source determination in Middle East

NASA Astrophysics Data System (ADS)

Karimi, Khadijeh; Taheri Shahraiyni, Hamid; Habibi Nokhandan, Majid; Hafezi Moghaddas, Naser; Sanaeifar, Melika

2011-11-01

The dust storm happens in the Middle East with very high frequency. According to the dust storm effects, it is vital to study on the dust storms in the Middle East. The first step toward the study on dust storm is the enhancement of dust storms and determination of the point sources. In this paper, a new false color composite (FCC) map for the dust storm enhancement and point sources determination in the Middle East has been developed. The 28 Terra-MODIS images in 2008 and 2009 were utilized in this study. We tried to replace the Red, Green and Blue bands in RGB maps with the bands or maps that enhance the dust storms. Hence, famous indices for dust storm detection (NDDI, D and BTD) were generated using the different bands of MODIS images. These indices with some bands of MODIS were utilized for FCC map generation with different combinations. Among the different combinations, four better FCC maps were selected and these four FCC are compared using visual interpretation. The results of visual interpretations showed that the best FCC map for enhancement of dust storm in the middle east is an especial combination of the three indices (Red: D, Green: BTD and Blue: NDDI). Therefore, we utilized of this new FCC method for the enhancement of dust storms and determination of point sources in Middle East.

Multi-Wavelength Views of Messier 81

NASA Technical Reports Server (NTRS)

2003-01-01

[figure removed for brevity, see original site] Click on individual images below for larger view

[figure removed for brevity, see original site]

[figure removed for brevity, see original site]

[figure removed for brevity, see original site]

[figure removed for brevity, see original site]

The magnificent spiral arms of the nearby galaxy Messier 81 are highlighted in this image from NASA's Spitzer Space Telescope. Located in the northern constellation of Ursa Major (which also includes the Big Dipper), this galaxy is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years.

The main image is a composite mosaic obtained with the multiband imaging photometer for Spitzer and the infrared array camera. Thermal infrared emission at 24 microns detected by the photometer (red, bottom left inset) is combined with camera data at 8.0 microns (green, bottom center inset) and 3.6 microns (blue, bottom right inset).

A visible-light image of Messier 81, obtained at Kitt Peak National Observatory, a ground-based telescope, is shown in the upper right inset. Both the visible-light picture and the 3.6-micron near-infrared image trace the distribution of stars, although the Spitzer image is virtually unaffected by obscuring dust. Both images reveal a very smooth stellar mass distribution, with the spiral arms relatively subdued.

As one moves to longer wavelengths, the spiral arms become the dominant feature of the galaxy. The 8-micron emission is dominated by infrared light radiated by hot dust that has been heated by nearby luminous stars. Dust in the galaxy is bathed by ultraviolet and visible light from nearby stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles are composed of silicates (chemically similar to beach sand), carbonaceous grains and polycyclic aromatic hydrocarbons and trace the gas distribution in the galaxy. The well-mixed gas (which is best detected at radio wavelengths) and dust provide a reservoir of raw materials for future star formation.

The 24-micron multiband imaging photometer image shows emission from warm dust heated by the most luminous young stars. The infrared-bright clumpy knots within the spiral arms show where massive stars are being born in giant H II (ionized hydrogen) regions. Studying the locations of these star forming regions with respect to the overall mass distribution and other constituents of the galaxy (e.g., gas) will help identify the conditions and processes needed for star formation.

Wind vs. Dust Devil Streaks

NASA Technical Reports Server (NTRS)

2004-01-01

22 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image presents a fine illustration of the difference between streaks made by dust devils and streaks made by wind gusts. Dust devils are usually solitary, spinning vortices. They resemble a tornado, or the swirling motion of a familiar, Tasmanian cartoon character. Wind gusts, on the other hand, can cover a larger area and affect more terrain at the same time. The dark, straight, and parallel features resembling scrape marks near the right/center of this image are thought to have been formed by a singular gust of wind, whereas the more haphazard dark streaks that crisscross the scene were formed by dozens of individual dust devils, acting at different times. This southern summer image is located in Noachis Terra near 67.0oS, 316.2oW. Sunlight illuminates the scene from the upper left; the picture covers an area 3 km (1.9 mi) wide.

House-Dust Allergy

PubMed Central

Johnson, C. A.

1982-01-01

House-dust allergy is a common cause of perennial allergic rhinitis and extrinsic asthma. Symptoms tend to be worse when the patient is in bed. A positive skin test properly performed and interpreted confirms the diagnosis. The house-dust mite is the most important antigenic component of house-dust. Treatment consists of environmental control directed at reducing the mite content of bedroom dust, plus control of symptoms with drugs. Immunotherapy is controversial. ImagesFig. 1 PMID:21286201

PPS GPS: What Is It? And How Do I Get It

DTIC Science & Technology

1994-06-01

Positioning Service, Selective Availabilit B.PRICE CODIE 17. SECURITY CLASSIFICATION II. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20...the TEC Water Detection Response Team which operates in remote areas of the world. These activities, require the GPS receiver to be capable of removing

Comparing Standard and Selective Degradation DNA Extraction Methods: Results from a Field Experiment with Sexual Assault Kits^.

PubMed

Campbell, Rebecca; Pierce, Steven J; Sharma, Dhruv B; Shaw, Jessica; Feeney, Hannah; Nye, Jeffrey; Schelling, Kristin; Fehler-Cabral, Giannina

2017-01-01

A growing number of U.S. cities have large numbers of untested sexual assault kits (SAKs) in police property facilities. Testing older kits and maintaining current case work will be challenging for forensic laboratories, creating a need for more efficient testing methods. We evaluated selective degradation methods for DNA extraction using actual case work from a sample of previously unsubmitted SAKs in Detroit, Michigan. We randomly assigned 350 kits to either standard or selective degradation testing methods and then compared DNA testing rates and CODIS entry rates between the two groups. Continuation-ratio modeling showed no significant differences, indicating that the selective degradation method had no decrement in performance relative to customary methods. Follow-up equivalence tests indicated that CODIS entry rates for the two methods could differ by more than ±5%. Selective degradation methods required less personnel time for testing and scientific review than standard testing. © 2016 American Academy of Forensic Sciences.

An assessment of SEVIRI imagery at different temporal resolutions and the effect on accurate dust emission mapping

NASA Astrophysics Data System (ADS)

Hennen, Mark; White, Kevin; Shahgedanova, Maria

2017-04-01

This paper compares Dust RGB products derived from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) data at 15 minute, 30 minute and hourly temporal resolutions. From January 2006 to December 2006, observations of dust emission point sources were observed at each temporal resolution across the entire Middle East region (38.50N; 30.00E - 10.00N; 65.50E). Previous work has demonstrated that 15-minute resolution SEVIRI data can be used to map dust sources across the Sahara by observing dust storms back through sequential images to the point of first emission (Schepanski et al., 2007; 2009; 2012). These observations have improved upon lower resolution maps, based on daily retrievals of aerosol optical depth (AOD), whose maxima can be biased by prevalent transport routes, not necessarily coinciding with sources of emissions. Based on the thermal contrast of atmospheric dust to the surface, brightness temperature differences (BTD's) in the thermal infrared (TIR) wavelengths (8.7, 10.8 and 12.0 µm) highlight dust in the scene irrespective of solar illumination, giving both increased accuracy of dust source areas and a greater understanding of diurnal emission behaviour. However, the highest temporal resolution available (15-minute repeat capture) produces 96 images per day, resulting in significantly higher data storage demands than 30 minute or hourly data. To aid future research planning, this paper investigates what effect lowering the temporal resolution has on the number and spatial distribution of the observed dust sources. The results show a reduction in number of dust emission events observed with each step decrease in temporal resolution, reducing by 17% for 30-minute resolution and 50% for hourly. These differences change seasonally, with the highest reduction observed in summer (34% and 64% reduction respectively). Each resolution shows a similar spatial distribution, with the biggest difference seen near the coastlines, where near-shore convective cloud patterns obscure atmospheric dust soon after emission, restricting the opportunity to be observed at hourly resolution.

First Dust Devil Seen by Opportunity

NASA Image and Video Library

2010-07-28

This is the first dust devil that NASA rover Opportunity has observed in the rover six and a half years on Mars. This image has been carefully calibrated and the contrast stretched to make the dust devil easier to see against the Martian sky.

Enigmatic Extinction: An Investigation of the 2175Å Extinction Bump in M101

NASA Astrophysics Data System (ADS)

Danowski, Meredith E.; Cook, Timothy; Gordon, Karl D.; Chakrabarti, Supriya; Lawton, Brandon L.; Misselt, Karl A.

2014-06-01

Evidence from studies of starburst galaxies indicates that active formation of high mass stars modifies the UV dust extinction curve as seen by a lack of the characteristic 2175Å bump. For over 45 years, the source of the 2175Å extinction feature has yet to be positively identified. Small aromatic/PAH grains are suggested as a leading contender in dust grain models. The face-on spiral galaxy M101 is an ideal laboratory for the study of dust, with many well-studied HII regions and a steep metallicity and ionization gradient.The Interstellar Medium Absorption Gradient Experiment Rocket (IMAGER) probes the correlation between dust extinction, and the metallicity and radiation environment in M101 at ultraviolet wavelengths. IMAGER simultaneously images M101 in three 400Å-wide bandpasses, measuring the apparent strength of the 2175Å bump and the UV continuum.Combining data from IMAGER with high S/N far- and near- UV observations from the MAMA detectors on the Hubble STIS instrument, we examine the apparent strength of the 2175Å bump in HII regions of M101. With additional infrared data from Spitzer, the DIRTY radiative transfer model, and stellar evolution models, we probe the correlation between the 2175Å feature and the aromatic/PAH features across HII regions of varying metallicity and radiation field hardness. The results of this experiment will directly impact our understanding of the nature of dust and our ability to accurately account for the effects of dust on observations at all redshifts.

Terra Sirenum

NASA Technical Reports Server (NTRS)

2002-01-01

[figure removed for brevity, see original site]

This image is from a region called Terra Sirenum in Mars' southern hemisphere. This region was named in 1958 for the Sea of the Sirens from Greek Mythology. This is not a sea, however, but a relatively dusty, high albedo region of Mars. There are numerous dust devil tracks that are apparent in the center- left of the image. The dust devils act like vacuum cleaners and lift dust off of the surface leaving a less dusty and relatively lower albedo surface behind. Dust devils are very common on Mars and are thought to be the primary mechanism for constantly lifting the dust into the atmosphere. Dust is constantly present in the Martian atmosphere in greater abundances than typically seen on Earth. The Martian dust is one of the main factors that affect the present Martian climate and clearly displays the relationship between Mars' geology and atmosphere.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Computer Model Predicts the Movement of Dust

NASA Technical Reports Server (NTRS)

2002-01-01

A new computer model of the atmosphere can now actually pinpoint where global dust events come from, and can project where they're going. The model may help scientists better evaluate the impact of dust on human health, climate, ocean carbon cycles, ecosystems, and atmospheric chemistry. Also, by seeing where dust originates and where it blows people with respiratory problems can get advanced warning of approaching dust clouds. 'The model is physically more realistic than previous ones,' said Mian Chin, a co-author of the study and an Earth and atmospheric scientist at Georgia Tech and the Goddard Space Flight Center (GSFC) in Greenbelt, Md. 'It is able to reproduce the short term day-to-day variations and long term inter-annual variations of dust concentrations and distributions that are measured from field experiments and observed from satellites.' The above images show both aerosols measured from space (left) and the movement of aerosols predicted by computer model for the same date (right). For more information, read New Computer Model Tracks and Predicts Paths Of Earth's Dust Images courtesy Paul Giroux, Georgia Tech/NASA Goddard Space Flight Center

The Infrared Hunter

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

This image composite compares infrared and visible views of the famous Orion nebula and its surrounding cloud, an industrious star-making region located near the hunter constellation's sword. The infrared picture is from NASA's Spitzer Space Telescope, and the visible image is from the National Optical Astronomy Observatory, headquartered in Tucson, Ariz.

In addition to Orion, two other nebulas can be seen in both pictures. The Orion nebula, or M42, is the largest and takes up the lower half of the images; the small nebula to the upper left of Orion is called M43; and the medium-sized nebula at the top is NGC 1977. Each nebula is marked by a ring of dust that stands out in the infrared view. These rings make up the walls of cavities that are being excavated by radiation and winds from massive stars. The visible view of the nebulas shows gas heated by ultraviolet radiation from the massive stars.

Above the Orion nebula, where the massive stars have not yet ejected much of the obscuring dust, the visible image appears dark with only a faint glow. In contrast, the infrared view penetrates the dark lanes of dust, revealing bright swirling clouds and numerous developing stars that have shot out jets of gas (green). This is because infrared light can travel through dust, whereas visible light is stopped short by it.

The infrared image shows light captured by Spitzer's infrared array camera. Light with wavelengths of 8 and 5.8 microns (red and orange) comes mainly from dust that has been heated by starlight. Light of 4.5 microns (green) shows hot gas and dust; and light of 3.6 microns (blue) is from starlight.

Cerberus Wind Streaks

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 6 May 2002) The Science Cerberus is a dark region on Mars that has shrunk down from a continuous length of about 1000 km to roughly three discontinuous spots a few 100 kms in length in less than 20 years. There are two competing processes at work in the Cerberus region that produce the bright and dark features seen in this THEMIS image. Bright dust settles out of the atmosphere, especially after global dust storms, depositing a layer just thick enough to brighten the dark surfaces. Deposition occurs preferentially in the low wind 'shadow zones' within craters and downwind of crater rims, producing the bright streaks. The direction of the streaks clearly indicates that the dominant winds come from the northeast. Dust deposition would completely blot out the dark areas if it were not for the action of wind-blown sand grains scouring the surface and lifting the dust back into the atmosphere. Again, the shadow zones are protected from the blowing sand, preserving the bright layer of dust. Also visible in this image are lava flow features extending from the flanks of the huge Elysium volcanoes to the northwest. Two shallow channels and a raised flow lobe are just barely discernable. The lava channel in the middle of the image crosses the boundary of the bright and dark surfaces without any obvious change in its morphology. This demonstrates that the bright dust layer is very thin in this location, perhaps as little as a few millimeters. The Story Mars is an ever-changing land of spectacular contrasts. This THEMIS image shows the Cerberus region of Mars, a dark area located near the Elysium volcanoes and fittingly named after the three-headed, dragon-tailed dog who guards the door of the underworld. Two opposing processes are at work here: a thin layer of dust falling from the atmosphere and/or dust storms creating brighter surface areas (e.g. the top left portion of this image) and dust being scoured away by the action of the Martian wind disturbing the sand grains and freeing the lighter dust to fly away once more (the darker portions of this image). There are, however, some darker areas that are somewhat shielded and protected from the wind that have yielded bright, dusty crater floors and wind streaks that trail out behind the craters. These wind streaks tell a story all their own as to the prevailing wind direction coming from the northeast. This, added to the fact that this dark region was once 1000 km in length and has dwindled to just a few isolated dark splotches of 100 kilometers in the past 20 years, help us to see that the Martian environment is still quite dynamic and capable of changing. Finally, this being a volcanic region, a lobe of a lava flow from the immense Elysium volcanoes to the northwest is visible stretching across the bottom one-quarter of the image.

Enhancing the Scientific Return from HST Imaging of Debris Disks

NASA Astrophysics Data System (ADS)

Weinberger, Alycia

2016-10-01

We propose realistic modeling of scattering of light by small aggregate dust grains that will enable us to interpret visible to near-infrared imaging of debris disks. We will determine if disk colors, phase functions, and polarizations place unique constraints on the composition of debris dust. Ongoing collisions of planetesimals generate dust; therefore, the dust provides unique information on compositions of the parent bodies. These exosolar analogs of asteroids and comets can bear clues to the history of a planetary system including migration and thermal processing. Because directly imaged debris disks are cold, they have no solid state emission features. Grain scattering properties as a function of wavelength are our only tool to reveal their compositions. Solar system interplanetary dust particles are fluffy aggregates, but most previous work on debris disk composition relied on Mie theory, i.e. assumed compact spherical grains. Mie calculations do not reproduce the observed colors and phase functions observed from debris disks. The few more complex calculations that exist do not explore the range of compositions and sizes relevant to debris disk dust. In particular, we expect porosity to help distinguish between cometary-like parent bodies, which are fluffy due to high volatile content and low collisional velocities, and asteroidal-like parent bodies that are compacted.

HUBBLE SPACE TELESCOPE AND HI IMAGING OF STRONG RAM PRESSURE STRIPPING IN THE COMA SPIRAL NGC 4921: DENSE CLOUD DECOUPLING AND EVIDENCE FOR MAGNETIC BINDING IN THE ISM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenney, Jeffrey D. P.; Abramson, Anne; Bravo-Alfaro, Hector, E-mail: jeff.kenney@yale.edu

Remarkable dust extinction features in the deep Hubble Space Telescope (HST) V and I images of the face-on Coma cluster spiral galaxy NGC 4921 show in unprecedented ways how ram pressure strips the ISM from the disk of a spiral galaxy. New VLA HI maps show a truncated and highly asymmetric HI disk with a compressed HI distribution in the NW, providing evidence for ram pressure acting from the NW. Where the HI distribution is truncated in the NW region, HST images show a well-defined, continuous front of dust that extends over 90° and 20 kpc. This dust front separatesmore » the dusty from dust-free regions of the galaxy, and we interpret it as galaxy ISM swept up near the leading side of the ICM–ISM interaction. We identify and characterize 100 pc–1 kpc scale substructure within this dust front caused by ram pressure, including head–tail filaments, C-shaped filaments, and long smooth dust fronts. The morphology of these features strongly suggests that dense gas clouds partially decouple from surrounding lower density gas during stripping, but decoupling is inhibited, possibly by magnetic fields that link and bind distant parts of the ISM.« less

Spring Dust Storm Smothers Beijing

NASA Technical Reports Server (NTRS)

2002-01-01

A few days earlier than usual, a large, dense plume of dust blew southward and eastward from the desert plains of Mongolia-quite smothering to the residents of Beijing. Citizens of northeastern China call this annual event the 'shachenbao,' or 'dust cloud tempest.' However, the tempest normally occurs during the spring time. The dust storm hit Beijing on Friday night, March 15, and began coating everything with a fine, pale brown layer of grit. The region is quite dry; a problem some believe has been exacerbated by decades of deforestation. According to Chinese government estimates, roughly 1 million tons of desert dust and sand blow into Beijing each year. This true-color image was made using two adjacent swaths (click to see the full image) of data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, on March 17, 2002. The massive dust storm (brownish pixels) can easily be distinguished from clouds (bright white pixels) as it blows across northern Japan and eastward toward the open Pacific Ocean. The black regions are gaps between SeaWiFS' viewing swaths and represent areas where no data were collected. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

SUV Tracks On Mars? The 'Devil' is in the Details

NASA Technical Reports Server (NTRS)

1998-01-01

Sport Utility Vehicles (SUVs) on Mars? Imagine the MOC imaging team's surprise on the morning of April 27, 1998, as the latest images came in from the 'Red Planet.'

A picture taken by the camera on Mars Global Surveyor just one day earlier showed several thin, dark lines that--at first glance--looked like pathways blazed by off-road sport utility vehicles. Who's been driving around on Mars?

The MOC image in question (#26403), seen here at full resolution of 13.8 meters (45 feet) per pixel, was obtained around 10:22 a.m. PDT on April 26, 1998, during Mars Global Surveyor's 264th orbit. North is approximately up, illumination is from the lower right. Located in eastern Arabia Terra near 16.5o N latitude, 311.4o W longitude, the image showed a number of natural features--small craters formed by meteor impact, several buttes and mesas left by erosion of the surrounding terrain, small dunes and drifts, and a mantle of dust that varies in thickness from place to place. But the new picture also showed two dark lines--each varying in width up to about 15 meters (49 feet)--that extended several kilometers/miles across the image.

Lines like these have been seen before on Mars. They are most likely the result of dust devils--columnar vortices of wind that move across the landscape, pick up dust, and look somewhat like miniature tornadoes. Dust devils are a common occurrence in dry and desert landscapes on Earth as well as Mars. They form when the ground heats up during the day, warming the air immediately above the surface. As pockets of warm air rise and interfere with one another, they create horizontal pressure variations that, combined with other meteorological winds, cause the upward moving air to spin (the direction of the spin is controlled by the same Coriolis forces that cause terrestrial hurricanes to spin in specific directions). As the spinning column of air moves across the surface, it occasionally encounters dust on the surface, which it can suck upward. This dust rises into the spinning air, giving the appearance of a tornado-like column that moves across the landscape. As the column of air moves, its ability to pick up dust varies--sometimes they hold a lot of dust and are nearly opaque; sometimes you cannot even see them. Dust-devils rarely last long, since their very motion changes the conditions that allowed them to form in the first place.

Mars Pathfinder detected the passage of several dust devils during its 83 days of operation on Mars in 1997. Mariner 9 and the Viking landers and orbiters of the 1970s also found evidence that dust devils occur on Mars; indeed, some Viking Orbiter images actually show dust devil clouds. MOC image 26403 is the latest entry in the body of evidence for the work of wind in the modern martian environment. The MOC Science Team is continuing to study these and other streaks caused by wind interacting with the martian surface.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

Comet 103P/Hartley 2 at perihelion: gas and dust activity

NASA Astrophysics Data System (ADS)

Lara, L. M.; Lin, Z.-Y.; Meech, K.

2011-08-01

Context. The comet 103P/Hartley 2, target of the EPOXI mission (NASA), was supposed to be observed for 3 days around its perihelion, from October 27 to 29, 2010, but photometric data were obtained only on October 27 and 29, 2010. On both dates, the comet visibility was not optimal due to its proximity to the Moon, as projected on the plane of the sky, whereas on October 28, the comet could not be observed at all. Aims: The goal of the campaign was to give ground support to the EPOXI mission by establishing a baseline of activity at perihelion to be compared with in situ activity observed by the space mission about 7 days later on Nov. 4, 2010. We aimed to assess gas and dust production rates, to study the gas and dust coma morphology, to investigate the behaviour of the refractory component by analysing the dust colour variations with date and with projected cometocentric distance, ρ, and to determine the slope of the surface brightness profiles, B, as a function of ρ. Methods: Long-slit spectra and optical broad- and narrowband images were acquired with the instrument ACAM mounted on the William Herschel Telescope (WHT) at La Palma Observatory. We investigated the evolution of the dust coma morphology from the images acquired with specific continuum cometary filters (in the blue and red wavelength region) with image-enhancing techniques. We studied (1) the gas and dust production rates; (2) the dust radial brightness profiles; (3) the profiles of the CN, C2, C3 and NH2 column densities, and (4) the CN and C3 coma morphologies. The dust and gas profiles were azimuthally averaged, as well as measured in both the E-W direction (~Sun-antisolar direction) and in a direction defined by the slit orientation at PA 70 to 250 degrees. Results: The morphological analysis of the dust coma reveals only one structure. Aside from the dust tail in the west direction, a bright jet is detected in images acquired on October 27 at 03:00-04:00 UT. This jet turns on and off and it is not clearly detected at any time on the images obtained during October 29. This structure is enhanced by making use of the radial renormalization and the Larson-Sekanina method. It is also confirmed by the distortion of the isophotes at the same position angle (PA). The Afρ parameter, a proxy to the dust production rate, and the gas (CN, C3, C2, and NH2) production rate, Qi, have been measured at perihelion, rh ≈ 1.058 AU. The quotient QC2/QCN ~ 1.3 places 103P/Hartley 2 as a typical comet in terms of long-chain hydrocarbon abundance. The gas-to-dust mass ratio is ~3-6, indicating that 103P/Hartley 2 is a relatively gas-rich comet. At perihelion, Afρ, as measured in a circular aperture of ~4700 km ranges from ~60 cm in the blue to ~110 cm in the red, which indicates an overall change in the optical properties of the dust grains. On the other hand, the Afρ is rather stable in the innermost coma when it is computed from the spectroscopic measurements within several continuum spectral ranges from 482-685 nm. Both 2D dust colour maps and profiles in the directions imposed by the slit indicate that there are variations with ρ with a trend towards bluer dust colour with increasing ρ. This could indicate sublimation of ices as the cameras on board the EPOXI mission have shown. The average dust reddening is ~24%/100 nm. The azimuthally averaged surface brightness profiles of the continuum from the broad band images can be well fitted with m ~ 1 in the tail direction, whereas in the opposite direction the dust profiles are much flatter at ρ ≤ 10 000 km. The azimuthally averaged profiles of the comet images acquired with the blue and red continuum cometary filters show a nominal behaviour of log B ~ - mlog ρ with m ~ 1. Based on observations made with the William Herschel Telescope (WHT) operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

Advances in Mineral Dust Source Composition Measurement with Imaging Spectroscopy at the Salton Sea, CA

NASA Astrophysics Data System (ADS)

Green, R. O.; Realmuto, V. J.; Thompson, D. R.; Mahowald, N. M.; Pérez García-Pando, C.; Miller, R. L.; Clark, R. N.; Swayze, G. A.; Okin, G. S.

2015-12-01

Mineral dust emitted from the Earth's surface is a principal contributor to direct radiative forcing over the arid regions, where shifts in climate have a significant impact on agriculture, precipitation, and desert encroachment around the globe. Dust particles contribute to both positive and negative forcing, depending on the composition of the particles. Particle composition is a function of the surface mineralogy of dust source regions, but poor knowledge of surface mineralogy on regional to global scales limits the skill of Earth System models to predict shifts in regional climate around the globe. Earth System models include the source, emission, transport and deposition phases of the dust cycle. In addition to direct radiative forcing contributions, mineral dust impacts include indirect radiative forcing, modification of the albedo and melting rates of snow and ice, kinetics of tropospheric photochemistry, formation and deposition of acidic aerosols, supply of nutrients to aquatic and terrestrial ecosystems, and impact on human health and safety. We demonstrate the ability to map mineral dust source composition in the Salton Sea dust source region with imaging spectroscopy measurements acquired as part of the NASA HyspIRI preparatory airborne campaign. These new spectroscopically derived compositional measurements provide a six orders of magnitude improvement over current atlases for this dust source region and provide a pathfinder example for a remote measurement approach to address this critical dust composition gap for global Earth System models.

Top-down estimate of dust emissions through integration of MODIS and MISR aerosol retrievals with the GEOS-Chem adjoint model

NASA Astrophysics Data System (ADS)

Wang, Jun; Xu, Xiaoguang; Henze, Daven K.; Zeng, Jing; Ji, Qiang; Tsay, Si-Chee; Huang, Jianping

2012-04-01

Predicting the influences of dust on atmospheric composition, climate, and human health requires accurate knowledge of dust emissions, but large uncertainties persist in quantifying mineral sources. This study presents a new method for combined use of satellite-measured radiances and inverse modeling to spatially constrain the amount and location of dust emissions. The technique is illustrated with a case study in May 2008; the dust emissions in Taklimakan and Gobi deserts are spatially optimized using the GEOS-Chem chemical transport model and its adjoint constrained by aerosol optical depth (AOD) that are derived over the downwind dark-surface region in China from MODIS (Moderate Resolution Imaging Spectroradiometer) reflectance with the aerosol single scattering properties consistent with GEOS-chem. The adjoint inverse modeling yields an overall 51% decrease in prior dust emissions estimated by GEOS-Chem over the Taklimakan-Gobi area, with more significant reductions south of the Gobi Desert. The model simulation with optimized dust emissions shows much better agreement with independent observations from MISR (Multi-angle Imaging SpectroRadiometer) AOD and MODIS Deep Blue AOD over the dust source region and surface PM10 concentrations. The technique of this study can be applied to global multi-sensor remote sensing data for constraining dust emissions at various temporal and spatial scales, and hence improving the quantification of dust effects on climate, air quality, and human health.

Top-down Estimate of Dust Emissions Through Integration of MODIS and MISR Aerosol Retrievals With the Geos-chem Adjoint Model

NASA Technical Reports Server (NTRS)

Wang, Jun; Xu, Xiaoguang; Henze, Daven K.; Zeng, Jing; Ji, Qiang; Tsay, Si-Chee; Huang, Jianping

2012-01-01

Predicting the influences of dust on atmospheric composition, climate, and human health requires accurate knowledge of dust emissions, but large uncertainties persist in quantifying mineral sources. This study presents a new method for combined use of satellite-measured radiances and inverse modeling to spatially constrain the amount and location of dust emissions. The technique is illustrated with a case study in May 2008; the dust emissions in Taklimakan and Gobi deserts are spatially optimized using the GEOSChem chemical transport model and its adjoint constrained by aerosol optical depth (AOD) that are derived over the downwind dark-surface region in China from MODIS (Moderate Resolution Imaging Spectroradiometer) reflectance with the aerosol single scattering properties consistent with GEOS-chem. The adjoint inverse modeling yields an overall 51% decrease in prior dust emissions estimated by GEOS-Chem over the Taklimakan-Gobi area, with more significant reductions south of the Gobi Desert. The model simulation with optimized dust emissions shows much better agreement with independent observations from MISR (Multi-angle Imaging SpectroRadiometer) AOD and MODIS Deep Blue AOD over the dust source region and surface PM10 concentrations. The technique of this study can be applied to global multi-sensor remote sensing data for constraining dust emissions at various temporal and spatial scales, and hence improving the quantification of dust effects on climate, air quality, and human health.

Dust Studies in DIII-D and TEXTOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudakov, D L; Litnovsky, A; West, W P

2009-02-17

Studies of naturally occurring and artificially introduced carbon dust are conducted in DIII-D and TEXTOR. In DIII-D, dust does not present operational concerns except immediately after entry vents. Submicron sized dust is routinely observed using Mie scattering from a Nd:Yag laser. The source is strongly correlated with the presence of Type I edge localized modes (ELMs). Larger size (0.005-1 mm diameter) dust is observed by optical imaging, showing elevated dust levels after entry vents. Inverse dependence of the dust velocity on the inferred dust size is found from the imaging data. Direct heating of the dust particles by the neutralmore » beam injection (NBI) and acceleration of dust particles by the plasma flows are observed. Energetic plasma disruptions produce significant amounts of dust. Large flakes or debris falling into the plasma may result in a disruption. Migration of pre-characterized carbon dust is studied in DIII-D and TEXTOR by introducing micron-size dust in plasma discharges. In DIII-D, a sample holder filled with {approx}30 mg of dust is introduced in the lower divertor and exposed to high-power ELMing H-mode discharges with strike points swept across the divertor floor. After a brief exposure ({approx}0.1 s) at the outer strike point, part of the dust is injected into the plasma, raising the core carbon density by a factor of 2-3 and resulting in a twofold increase of the radiated power. In TEXTOR, instrumented dust holders with 1-45 mg of dust are exposed in the scrape-off layer 0-2 cm radially outside of the last closed flux surface in discharges heated with neutral beam injection (NBI) power of 1.4 MW. At the given configuration of the launch, the dust did not penetrate the core plasma and only moderately perturbed the edge plasma, as evidenced by an increase of the edge carbon content.« less

Parameterizing the dust around Herbig Ae/Be stars: Multiwavelength imaging radiative transfer modeling, and near-infrared instrumentation

NASA Astrophysics Data System (ADS)

Doering, Ryan Lee

Herbig Ae/Be stars are considered the intermediate-mass analogs of the low-mass pre-main sequence T Tauri stars. Observations reveal that they are surrounded by dusty matter that may provide the solid-state material for building planets. Determining the dust parameters provides constraints for planet formation theory, and yields information about the matter around intermediate-mass stars as they approach the main sequence. In this dissertation, I present the results of a multiwavelength imaging and radiative transfer modeling study of Herbig Ae/Be stars, and a near-infrared instrumentation project, with the aim of parameterizing the dust in these systems. The Hubble Space Telescope was used to search for optical light scattered by dust in a sample of young stars. This survey provided the first scattered-light image of the circumstellar environment around the Herbig Ae/Be star HD 97048. Structure is observed in the dust distribution similar to that seen in other Herbig Ae/Be systems. A ground-based near-infrared imaging study of Herbig Ae/ Be candidates was also carried out. Photometry was collected for spectral energy distribution construction, and binary candidates were resolved. A mid- infrared image of the low-mass debris system, AU Microscopii, is presented, being relevant to the study of Herbig Ae/Be stars. Detailed dust modeling of HD 97048 and HD 100546 was carried out with a two- component geometry consisting of a flared disk and an extended envelope. The models achieve a reasonable global fit to the spectral energy distributions, and produce images with the desired geometry. The disk midplane densities are found to go as r -0.5 and r -1.8 , giving disk dust masses of 3.0 × 10^-4 and 5.9 × 10 ^5 [Special characters omitted.] for HD 97048 and HD 100546, respectively. A gas-to-dust mass ratio lower limit of 3.2 was calculated for HD 97048. In order to advance the imaging capabilities available for observations of Herbig Ae/Be stars, I have participated in the development of the WIYN High Resolution Infrared Camera. The instrument operates in the near-infrared (~0.8 - 2.5 mm), includes 13 filters, and has a pixel size of ~0.1 inches, resulting in a field of view of ~3' × 3'. An angular resolution of ~0.25 inches is anticipated. I provide an overview of the instrument, and report performance results with an emphasis on detector characterization.

Laboratory Measurements of Radar Transmission Through Dust with Implications for Radar Imaging on Mars

NASA Technical Reports Server (NTRS)

Williams, K. K.; Greeley, R.

2001-01-01

Measurements of radar transmission through a Mars analog dust are used to calculate values of signal attenuation over a frequency range of 0.5-12 GHz. These values are discussed in the context of a Mars radar imaging mission. Additional information is contained in the original extended abstract.

Mars Atmospheric Temperature and Dust Storm Tracking

NASA Image and Video Library

2016-06-09

This graphic overlays Martian atmospheric temperature data as curtains over an image of Mars taken during a regional dust storm. The temperature profiles extend from the surface to about 50 miles (80 kilometers) up. Temperatures are color coded, ranging from minus 243 degrees Fahrenheit (minus 153 degrees Celsius) where coded purple to minus 9 F (minus 23 C) where coded red. The temperature data and global image were both recorded on Oct. 18, 2014, by instruments on NASA's Mars Reconnaissance Orbiter: Mars Climate Sounder and Mars Color Imager. On that day a regional dust storm was active in the Acidalia Planitia region of northern Mars, at the upper center of this image. A storm from this area in typically travels south and grows into a large regional storm in the southern hemisphere during southern spring. That type of southern-spring storm and two other large regional dust storms repeat as a three-storm series most Martian years. The pattern has been identified from their effects on atmospheric temperature in a layer about 16 miles (25 kilometers) above the surface. http://photojournal.jpl.nasa.gov/catalog/PIA20747

77 FR 50163 - Manufacturer of Controlled Substances, Notice of Registration, Cody Laboratories, Inc.

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-20

... DEPARTMENT OF JUSTICE Drug Enforcement Administration Manufacturer of Controlled Substances..., Wyoming 82414, made application by letter to the Drug Enforcement Administration (DEA) to be registered as a bulk manufacturer of the following basic classes of controlled substances: Drug Schedule 4-Anilino...

Chapter 4: The Cretaceous-Lower Tertiary Composite Total Petroleum System, Wind River Basin, Wyoming

USGS Publications Warehouse

Johnson, R.C.; Finn, Thomas M.; Kirschbaum, Mark A.; Roberts, Stephen B.; Roberts, Laura N.R.; Cook, Troy; Taylor, David J.

2007-01-01

The Cretaceous-Lower Tertiary Composite Total Petroleum System (TPS) of the Wind River Basin Province includes all strata from the base of the Lower Cretaceous Cloverly Formation to the base of the Waltman Shale Member of the Paleocene age Fort Union Formation and, where the Waltman is absent, includes strata as young as the Eocene Wind River Formation. Locally, Cretaceous-sourced gas migrated into strata as old as the Mississippian Madison Limestone, and in these areas the TPS extends stratigraphically downward to include these reservoirs. The extensive vertical migration of gases in highly fractured areas of the Wind River Basin led to the commingling of gases from several Upper Cretaceous and lower Tertiary sources, thus only two petroleum systems are recognized in these rocks, the Cretaceous-Lower Tertiary Composite TPS, the subject of this report, and the Waltman Shale TPS described by Roberts and others (Chapter 5, this CD-ROM). The Cretaceous-lower Tertiary Composite TPS was subdivided into (1) seven continuous gas assessment units (AU): (a) Frontier-Muddy Continuous Gas AU, (b) Cody Sandstone Continuous Gas AU, (c) Mesaverde--Meeteetse Sandstone Gas AU, (d) Lance-Fort Union Sandstone Gas AU, (e) Mesaverde Coalbed Gas AU, (f) Meeteetse Coalbed Gas AU, and (g) Fort Union Coalbed Gas AU; (2) one continuous oil assessement unit--- Cody Fractured Shale Continuous Oil AU; and (3) one conventional assessment Unit--- Cretaceous-Tertiary Conventional Oil and Gas AU. Estimates of undiscovered resources having the potential for additions to reserves were made for all but the Cody Fractured Shale Continuous Oil AU, which is considered hypothetical and was not quantitively assessed. The mean estimate of the total oil is 41.99 million barrels, mean estimate of gas is 2.39 trillion cubic feet, and mean estimate of natural gas liquids is 20.55 million barrels. For gas, 480.66 billion cubic feet (BCFG) is estimated for the Frontier-Muddy Continuous Gas AU, 115.34 BCFG for the Cody Sandstone Continuous Gas AU, 383.16 BCFG for the Mesaverde-Meeteetse Sandstone Continuous Gas AU, 711.30 BCFG for the Lance-Fort Union Sandstone Gas AU, 107.18 BCFG for the Mesaverde Coalbed Gas AU, 21.29 BCFG for the Meeteetse Coalbed Gas AU, and 118.08 BCFG for the Fort Union Coalbed Gas AU. All the undiscovered oil and 98.94 BCFG of undiscovered gas is in the Cretaceous-Tertiary Conventional Oil and Gas AU.

A new dust source map of Central Asia derived from MODIS Terra/Aqua data using dust enhancement techniques

NASA Astrophysics Data System (ADS)

Nobakht, Mohamad; Shahgedanova, Maria; White, Kevin

2017-04-01

Central Asian deserts are a significant source of dust in the middle latitudes, where economic activity and health of millions of people are affected by dust storms. Detailed knowledge of sources of dust, controls over their activity, seasonality and atmospheric pathways are of crucial importance but to date, these data are limited. This paper presents a detailed database of sources of dust emissions in Central Asia, from western China to the Caspian Sea, obtained from the analysis of the Moderate Resolution Imaging Spectroradiometer (MODIS) data between 2003 and 2012. A dust enhancement algorithm was employed to obtain two composite images per day at 1 km resolution from MODIS Terra/Aqua acquisitions, from which dust point sources (DPS) were detected by visual analysis and recorded in a database together with meteorological variables at each DPS location. Spatial analysis of DPS has revealed several active source regions, including some which were not widely discussed in literature before (e.g. Northern Afghanistan sources, Betpak-Dala region in western Kazakhstan). Investigation of land surface characteristics and meteorological conditions at each source region revealed mechanisms for the formation of dust sources, including post-fire wind erosion (e.g. Lake Balkhash basin) and rapid desertification (e.g. the Aral Sea). Different seasonal patterns of dust emissions were observed as well as inter-annual trends. The most notable feature was an increase in dust activity in the Aral Kum.

Sahara Dust Cloud

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24

A continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean.

These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward.

In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the cloud in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no clouds present on top of the dust; when clouds are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005.

In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust Cloud Click on the image for Quicktime movie

The dust cloud is contained within a dry adiabatic layer which originates over the Sahara Desert. This Saharan Air Layer (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the AIRS retrieved total water vapor product as a region of depressed water vapor (brown in the images) migrating slowly Westward toward the Caribbean. The SAL phenomenon inhibits the formation of tropical cyclones and thus has given the West Indies and the East Coast of the US a respite from hurricanes.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

Dust studies in DIII-D and TEXTOR

NASA Astrophysics Data System (ADS)

Rudakov, D. L.; Litnovsky, A.; West, W. P.; Yu, J. H.; Boedo, J. A.; Bray, B. D.; Brezinsek, S.; Brooks, N. H.; Fenstermacher, M. E.; Groth, M.; Hollmann, E. M.; Huber, A.; Hyatt, A. W.; Krasheninnikov, S. I.; Lasnier, C. J.; McLean, A. G.; Moyer, R. A.; Pigarov, A. Yu.; Philipps, V.; Pospieszczyk, A.; Smirnov, R. D.; Sharpe, J. P.; Solomon, W. M.; Watkins, J. G.; Wong, C. P. C.

2009-08-01

Studies of naturally occurring and artificially introduced carbon dust are conducted in DIII-D and TEXTOR. In DIII-D, dust does not present operational concerns except immediately after entry vents. Submicrometre sized dust is routinely observed using Mie scattering from a Nd : Yag laser. The source is strongly correlated with the presence of type I edge localized modes (ELMs). Larger size (0.005-1 mm diameter) dust is observed by optical imaging, showing elevated dust levels after entry vents. Inverse dependence of the dust velocity on the inferred dust size is found from the imaging data. Heating of the dust particles by the neutral beam injection (NBI) and acceleration of dust particles by the plasma flows are observed. Energetic plasma disruptions produce significant amounts of dust; on the other hand, large flakes or debris falling into the plasma may induce a disruption. Migration of pre-characterized carbon dust is studied in DIII-D and TEXTOR by introducing micrometre-size particles into plasma discharges. In DIII-D, a sample holder filled with 30-40 mg of dust is inserted in the lower divertor and exposed, via sweeping of the strike points, to the diverted plasma flux of high-power ELMing H-mode discharges. After a brief dwell (~0.1 s) of the outer strike point on the sample holder, part of the dust penetrates into the core plasma, raising the core carbon density by a factor of 2-3 and resulting in a twofold increase in the radiated power. In TEXTOR, instrumented dust holders with 1-45 mg of dust are exposed in the scrape-off-layer 0-2 cm radially outside of the last closed flux surface in discharges heated with 1.4 MW of NBI. Launched in this configuration, the dust perturbed the edge plasma, as evidenced by a moderate increase in the edge carbon content, but did not penetrate into the core plasma.

SN 1987A after 18 Years: Mid-Infrared GEMINI and SPITZER Observations of the Remnant

NASA Technical Reports Server (NTRS)

Bouchet, Patrice; Dwek, Eli; Danziger, John; Arendt, Richard G.; DeBuizer, James M.; Park, Sangwook; Suntzeff, Nicholas B.; Kirshner, Robert P.; Challis, Peter

2007-01-01

We present high resolution 11.7 and 18.3 micron mid-IR images of SN 1987A obtained on day 6526 since the explosion with the Thermal-Region Camera and Spectrograph (T-ReCS) attached to the Gemini South 8m telescope. The 11.7 micron flux has increased significantly since our last observations on day 6067. The images clearly show that all the emission arises from the equatorial ring (ER). Nearly contemporaneous spectra obtained on day 6184 with the MIPS at 24 micron, on day 6130 with the IRAC in 3.6- 8 micron region, and on day 6190 with the IRS in the 12-37 micron instruments on board the Spitzer Space Telescope's show that the emission consists of thermal emission from silicate dust that condensed out in the red giant wind of the progenitor star. The dust temperature is 1662(sup +18) (sub -12) K, and the emitting dust mass is (2.6(sup +2.0 (sub -1.4)) x 10 (exp -6) M(solar). Lines of [Ne II] 12.82 micron and [Ne III] 15.56 pm are clearly present in the Spitzer spectrum, as well as a weak [Si II] 3 34.8 micron line. We also detect two lines near 26 micron which we tentatively ascribe to [Fe II] 25.99 pm and [0 IV] 25.91 micron. Comparison of the mid-IR Gemini 11.7 micron image with X-ray images obtained by Chandra, UV-optical images obtained by HST, and radio synchrotron images obtained by the ATCA show generally good correlation of the images across all wavelengths. Because of the limited resolution of the mid-IR images we cannot uniquely determine the location. or heating mechanism of the dust giving rise to the emission. The dust could be collisionally heated by the X-ray emitting plasma, providing a unique diagnostic of plasma conditions. Alternatively, the dust could be radiatively heated in the dense UV-optical knots that are overrun by the advancing supernova blast wave. In either case the dust-to-gas mass ratio in the circumstellar medium around the supernova is significantly lower than that in the general interstellar medium of the LMC, suggesting either a low condensation efficiency in the wind of the progenitor star, or the efficient destruction of the dust by the SN blast wave. Overall, we are witnessing the interaction of the SN blast wave with its surrounding medium, creating an environment that is rapidly evolving at all wavelengths. Continuous multiwavelength observations of SN 1987A such as these provide unique snapshots of the very early evolution of supernova remnants.

Dust devils on Mars

NASA Astrophysics Data System (ADS)

Thomas, P.; Gierasch, P. J.

1985-10-01

Viking Orbiter photographic imagery has confirmed the occurrence of dust devils on Mars. The images were of small bright clouds with long, tapered shadows viewed from a nearly-nadir angle. Spectra of the features were consistent with dust and not condensates. A maximum height of 6.8 km and width of 1 km were measured. The dust devils appeared on smooth planes, and had average dimensions of 2 km height and 200 m diam, carrying 3000 kg of dust. The data may be of use in interpreting convective processes on earth.

Formal Specification and Verification of Concurrent Programs

DTIC Science & Technology

1993-02-01

of examples from the emerging theory of This book describes operating systems in general programming languages. via the construction of MINIX , a UNIX...look-alike that runs on IBM-PC compatibles. The book con- Wegner72 tains a complete MINIX manual and a complete Wegnerflisting of its C codie. egner

77 FR 60143 - Importer of Controlled Substances; Notice of Registration; Cody Laboratories, Inc.

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-02

... importer of the following basic classes of controlled substances: Drug Schedule Opium, raw (9600) II Concentrate Poppy Straw (9670) II Tapentadol (9780) II The company plans to import narcotic raw materials for... several controlled substances that are manufactured from opium raw, and poppy straw concentrate. The...

Imagine...Opportunities and Resources for Academically Talented Youth, 1999-2000.

ERIC Educational Resources Information Center

Hartman, Melissa E., Ed.

2000-01-01

Designed to encourage gifted students to develop their talents, the first issue in the volume focuses on academic competitions and includes articles on: "The Joys of Competition"; "Why Bother with Math Contests?" (Sam Vandervelde); "Science Competitions"; Humanities Competitions"; "Designing in Metal" (Cody Chance); and "Discovering My Chinese…

Does reproduction compromise defense in woody plants?

Treesearch

Daniel A. Herms; William J. Mattson

1991-01-01

A general principle of adaptive allocation was proposed by Cody (1966) who hypothesized that 1) all living organisms have finite resources to partition among growth and competing physiological processes such as reproduction and defense; and 2) natural selection results in the evolution of unique resource allocation patterns that maximize fitness in different...

Multitemporal observations of identical active dust devils on Mars with the High Resolution Stereo Camera (HRSC) and Mars Orbiter Camera (MOC)

NASA Astrophysics Data System (ADS)

Reiss, D.; Zanetti, M.; Neukum, G.

2011-09-01

Active dust devils were observed in Syria Planum in Mars Observer Camera - Wide Angle (MOC-WA) and High Resolution Stereo Camera (HRSC) imagery acquired on the same day with a time delay of ˜26 min. The unique operating technique of the HRSC allowed the measurement of the traverse velocities and directions of motion. Large dust devils observed in the HRSC image could be retraced to their counterparts in the earlier acquired MOC-WA image. Minimum lifetimes of three large (avg. ˜700 m in diameter) dust devils are ˜26 min, as inferred from retracing. For one of these large dust devil (˜820 m in diameter) it was possible to calculate a minimum lifetime of ˜74 min based on the measured horizontal speed and the length of its associated dust devil track. The comparison of our minimum lifetimes with previous published results of minimum and average lifetimes of small (˜19 m in diameter, avg. min. lifetime of ˜2.83 min) and medium (˜185 m in diameter, avg. min. lifetime of ˜13 min) dust devils imply that larger dust devils on Mars are active for much longer periods of time than smaller ones, as it is the case for terrestrial dust devils. Knowledge of martian dust devil lifetimes is an important parameter for the calculation of dust lifting rates. Estimates of the contribution of large dust devils (>300-1000 m in diameter) indicate that they may contribute, at least regionally, to ˜50% of dust entrainment by dust devils into the atmosphere compared to the dust devils <300 m in diameter given that the size-frequency distribution follows a power-law. Although large dust devils occur relatively rarely and the sediment fluxes are probably lower compared to smaller dust devils, their contribution to the background dust opacity by dust devils on Mars could be at least regionally large due to their longer lifetimes and ability of dust lifting into high atmospheric layers.

Clouds and Dust Storms

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site]

Released 2 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

Image information: VIS instrument. Latitude 68.4, Longitude 180 East (180 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Trans-Pacific transport of Asian dust: the CESM model analysis and comparison with satellite observations

NASA Astrophysics Data System (ADS)

Wu, M.; Liu, X.; Luo, T.; Wang, Z.; Yang, K.; Wu, C.; Wang, H.; Zhang, K.

2017-12-01

Mineral dust plays an important role in the Earth's climate system due to its effects on radiation budgets, clouds, chemistry and biosphere. However, modeled dust aerosol is not well constrained and large uncertainties exist in modeled dust lifecycles. We evaluate dust spatial distributions in the Community Earth System Model (CESM) with new dust extinction retrievals (Luo et al., 2015a, b) based on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO) and CloudSat measurement, with special focus on the Asian dust transport across the Pacific. It is shown that the default CESM underestimates the dust extinction over the Pacific by 1-2 order of magnitude. Especially, the model fails to capture the observed high values of dust extinction occurring from 850 to 500 hPa across the North Pacific (20°N-50°N). Modeled dust optical depth (DOD) decreases faster across the Pacific compared to the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multi-angle Imaging SpectroRadiometer (MISR) observations. Sensitivity experiments with altered emission, vertical transport and deposition schemes have been conducted to identify the key process impacting dust transport. For that purpose, two new dust emission schemes by Kok et al. (2014a, b) and Ginoux et al. (2001), a new dry deposition scheme by Petroff and Zhang (2010) are implemented to the CESM. In addition, a new unified scheme for convective transport and wet removal of aerosols (Wang et al., 2013) is implemented to the same version of CESM to examine the influence of convective transport and wet deposition on dust transport. It is found that changes in wet scavenging and convective transport can strongly impact dust transport over the Pacific compared to changes in other processes. One of the new emission schemes further decreases the dust extinction across the Pacific. Dust extinction across the Pacific slightly increases when dry deposition velocity for fine particles is reduced.

Casting Light and Shadows on a Saharan Dust Storm

NASA Technical Reports Server (NTRS)

2003-01-01

On March 2, 2003, near-surface winds carried a large amount of Saharan dust aloft and transported the material westward over the Atlantic Ocean. These observations from the Multi-angle Imaging SpectroRadiometer (MISR) aboard NASA's Terra satellite depict an area near the Cape Verde Islands (situated about 700 kilometers off of Africa's western coast) and provide images of the dust plume along with measurements of its height and motion. Tracking the three-dimensional extent and motion of air masses containing dust or other types of aerosols provides data that can be used to verify and improve computer simulations of particulate transport over large distances, with application to enhancing our understanding of the effects of such particles on meteorology, ocean biological productivity, and human health.

MISR images the Earth by measuring the spatial patterns of reflected sunlight. In the upper panel of the still image pair, the observations are displayed as a natural-color snapshot from MISR's vertical-viewing (nadir) camera. High-altitude cirrus clouds cast shadows on the underlying ocean and dust layer, which are visible in shades of blue and tan, respectively. In the lower panel, heights derived from automated stereoscopic processing of MISR's multi-angle imagery show the cirrus clouds (yellow areas) to be situated about 12 kilometers above sea level. The distinctive spatial patterns of these clouds provide the necessary contrast to enable automated feature matching between images acquired at different view angles. For most of the dust layer, which is spatially much more homogeneous, the stereoscopic approach was unable to retrieve elevation data. However, the edges of shadows cast by the cirrus clouds onto the dust (indicated by blue and cyan pixels) provide sufficient spatial contrast for a retrieval of the dust layer's height, and indicate that the top of layer is only about 2.5 kilometers above sea level.

Motion of the dust and clouds is directly observable with the assistance of the multi-angle 'fly-over' animation (Below). The frames of the animation consist of data acquired by the 70-degree, 60-degree, 46-degree and 26-degree forward-viewing cameras in sequence, followed by the images from the nadir camera and each of the four backward-viewing cameras, ending with 70-degree backward image. Much of the south-to-north shift in the position of the clouds is due to geometric parallax between the nine view angles (rather than true motion), whereas the west-to-east motion is due to actual motion of the clouds over the seven minutes during which all nine cameras observed the scene. MISR's automated data processing retrieved a primarily westerly (eastward) motion of these clouds with speeds of 30-40 meters per second. Note that there is much less geometric parallax for the cloud shadows owing to the relatively low altitude of the dust layer upon which the shadows are cast (the amount of parallax is proportional to elevation and a feature at the surface would have no geometric parallax at all); however, the westerly motion of the shadows matches the actual motion of the clouds. The automated processing was not able to resolve a velocity for the dust plume, but by manually tracking dust features within the plume images that comprise the animation sequence we can derive an easterly (westward) speed of about 16 meters per second. These analyses and visualizations of the MISR data demonstrate that not only are the cirrus clouds and dust separated significantly in elevation, but they exist in completely different wind regimes, with the clouds moving toward the east and the dust moving toward the west.

[figure removed for brevity, see original site]

(Click on image above for high resolution version)

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. These data products were generated from a portion of the imagery acquired during Terra orbit 17040. The panels cover an area of about 312 kilometers x 242 kilometers, and use data from blocks 74 to 77 within World Reference System-2 path 207.

MISR was built and is managed by NASA's Jet Propulsion Laboratory,Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyra, Wladimir; Lin, Min-Kai, E-mail: wlyra@caltech.edu, E-mail: mklin924@cita.utoronto.ca

The Atacama Large Millimeter Array has returned images of transitional disks in which large asymmetries are seen in the distribution of millimeter sized dust in the outer disk. The explanation in vogue borrows from the vortex literature and suggests that these asymmetries are the result of dust trapping in giant vortices, excited via Rossby wave instabilities at planetary gap edges. Due to the drag force, dust trapped in vortices will accumulate in the center and diffusion is needed to maintain a steady state over the lifetime of the disk. While previous work derived semi-analytical models of the process, in thismore » paper we provide analytical steady-steady solutions. Exact solutions exist for certain vortex models. The solution is determined by the vortex rotation profile, the gas scale height, the vortex aspect ratio, and the ratio of dust diffusion to gas-dust friction. In principle, all of these quantities can be derived from observations, which would validate the model and also provide constrains on the strength of the turbulence inside the vortex core. Based on our solution, we derive quantities such as the gas-dust contrast, the trapped dust mass, and the dust contrast at the same orbital location. We apply our model to the recently imaged Oph IRS 48 system, finding values within the range of the observational uncertainties.« less

Hypervelocity Dust Injection for Plasma Diagnostic Applications

NASA Astrophysics Data System (ADS)

Ticos, Catalin

2005-10-01

Hypervelocity micron-size dust grain injection was proposed for high-temperature magnetized plasma diagnosis. Multiple dust grains are launched simultaneously into high temperature plasmas at several km/s or more. The hypervelocity dust grains are ablated by the electron and ion fluxes. Fast imaging of the resulting luminous plumes attached to each grain is expected to yield local magnetic field vectors. Combination of multiple local magnetic field vectors reproduces 2D or even 3D maps of the internal magnetic field topology. Key features of HDI are: (1) a high spatial resolution, due to a relatively small transverse size of the elongated tail, and (2) a small perturbation level, as the dust grains introduce negligible number of particles compared to the plasma particle inventory. The latter advantage, however, could be seriously compromised if the gas load from the accelerator has an unobstructed access to the diagnosed plasma. Construction of a HDI diagnostic for National Spherical Torus Experiment (NSTX), which includes a coaxial plasma gun for dust grain acceleration, is underway. Hydrogen and deuterium gas discharges inside accelerator are created by a ˜ 1 mF capacitor bank pre-charged up to 10 kV. The diagnostic apparatus also comprises a dust dispenser for pre-loading the accelerator with dust grains, and an imaging system that has a high spatial and temporal resolution.

Dust Plume off the Coast of Egypt

NASA Technical Reports Server (NTRS)

2007-01-01

Dwarfing the Nile, a river of dust flowed out of the deserts of northern Egypt on May 19, 2007. As the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite passed overhead at 12:05 p.m. local time in Cairo, the sensor captured this image of the dust spreading northward over the Mediterranean Sea from the sandy deserts that span the country. At the margins of the plume, ribbons and ripples of dust are translucent, allowing a glimpse of the desert and water beneath, but in the center, the cloud is opaque, revealing nothing of the surface below. The part of north-central Egypt hidden by the dust plume is the Qattara Depression, the country's lowest point. Dipping down to 133 meters below sea level (436 feet), the depression is home to sandy deserts and dry lake beds that occasionally flood. The sand and fine, lake bed sediments are easily lofted into the air by strong winds that scour the area in late winter and early spring. In the eastern (right-hand) part of the image, the Nile River is lined by narrow ribbons of dull green vegetation. The fan-shaped delta is dotted with tan-colored spots, marking the location of cities and towns. The Nile Valley and Delta make up only a small fraction of the country's total land area, yet they support almost the entire population. The large image provided above has a spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response Team provides this image in additional resolutions. The Earth Observatory also provides a 250-meter-resolution KMZ file of this image for use with Google Earth.

Debris Disk Dust Characterization through Spectral Types: Deep Visible-Light Imaging of Nine Systems

NASA Astrophysics Data System (ADS)

Choquet, Elodie

2017-08-01

We propose STIS coronagraphy of 9 debris disks recently seen in the near-infrared from our re-analysis of archival NICMOS data. STIS coronagraphy will provide complementary visible-light images that will let us characterize the disk colors needed to place constraints on dust grain sizes, albedos, and anisotropy of scattering of these disks. With 3 times finer angular resolution and much better sensitivity, our STIS images will dramatically surpass the NICMOS discovery images, and will more clearly reveal disk local structures, cleared inner regions, and test for large-scale asymmetries in the dust distributions possibly triggered by associated planets in these systems. The exquisite sensitivity to visible-light scattering by submicron particles uniquely offered by STIS coronagraphy will let us detect and spatially characterize the diffuse halo of dust blown out of the systems by the host star radiative pressure. Our sample includes disks around 3 low-mass stars, 3 solar-type stars, and 3 massive A stars; together with our STIS+NICMOS imaging of 6 additional disks around F and G stars, our sample covers the full range of spectral types and will let us perform a comparative study of dust distribution properties as a function of stellar mass and luminosity. Our sample makes up more than 1/3 of all debris disks imaged in scattered light to date, and will offer the first homogeneous characterization of the visible-light to near-IR properties of debris disk systems over a large range of spectral types. Our program will let us analyze how the dynamical balance is affected by initial conditions and star properties, and how it may be perturbed by gas drag or planet perturbations.

Near-infrared morphology of protoplanetary nebulae - The icy dust torus of Minkowski's Footprint (M1-92)

NASA Technical Reports Server (NTRS)

Eiroa, C.; Hodapp, K.-W.

1989-01-01

High-resolution near-infrared images and ice-band spectra of the protoplanetary nebula M1-92 (Minkowski's Footprint) are presented. The direct images of the object display a typical bipolar morphology with the star located in the center of the nebula illuminating two lobes. The overall dimensions are the same in the J, H, and K infrared bands, and they are similar to those in the optical range. The near-infrared color images clearly reveal a dust torus around the central star. The orientation of the object in the plane of the sky allows the simultaneous view of the illuminating star, the nebular lobes, and the dust torus in a highly favorable perspective, only rarely found in other bipolar nebulae. The ice-band spectra make it possible to locate the H2O-ice grains within the dust torus; in addition, the narrow ice feature indicates that the ices are primarily pure crystalline water.

Martian Dust Storm on May 18, 2008

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site] Click on image for animation

This false-color polar map was generated from images obtained by the Mars Reconnaissance Orbiter's Mars Color Imager (MARCI) on May 18, 2008. It shows a large local dust storm that researchers were monitoring to see if it would affect weather conditions at NASA's Phoenix spacecraft's landing site on landing day, May 25, 2008. The landing site is labeled and marked with the yellow dot.

The dust storm, indicated with yellow arrows in the close-up view, is the sinuous, light-colored feature to the left of the white northern polar cap at the center of the map.

This dust storm was too early and too far away to affect the lander.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Dust Removal Target on 'Vera Rubin Ridge'

NASA Image and Video Library

2017-11-01

This image from the Mars Hand Lens Imager (MAHLI) camera on NASA's Curiosity Mars rover shows effects of using the rover's wire-bristled Dust Removal Tool (DRT) on a rock target called "Christmas Cove." The tool brushed an area about 2.5 inches (6 centimeters) across on Sept. 16, 2017, during the 1,118th Martian day, or sol of Curiosity's work on Mars. MAHLI took this image later the same sol. Both DRT and MAHLI are on the turret of tools at the end of Curiosity's arm. The site is partway up "Vera Rubin Ridge" on lower Mount Sharp, in an area where reconnaissance imaging with science filters revealed variability in indications of the mineral hematite. Removing dust from part of the Christmas Cove target was part of an experiment to check whether dust is subduing the apparent indications of hematite in some of the area's bedrock. The brushed area's purplish tint in this MAHLI image, accentuated even more when observed with science filters of the rover's Mast Camera, is characteristic of fine-grained hematite. Brushing of this target also exposed details in the fine layering and bright veins within the bedrock of this part of Vera Rubin Ridge. The image is oriented so that sunlight comes from upper left. Layers are lower (older) toward lower right. https://photojournal.jpl.nasa.gov/catalog/PIA22064

HERschel Observations of Edge-on Spirals (HEROES). III. Dust energy balance study of IC 2531

NASA Astrophysics Data System (ADS)

Mosenkov, Aleksandr V.; Allaert, Flor; Baes, Maarten; Bianchi, Simone; Camps, Peter; De Geyter, Gert; De Looze, Ilse; Fritz, Jacopo; Gentile, Gianfranco; Hughes, Thomas M.; Lewis, Fraser; Verstappen, Joris; Verstocken, Sam; Viaene, Sébastien

2016-07-01

We investigate the dust energy balance for the edge-on galaxy IC 2531, one of the seven galaxies in the HEROES sample. We perform a state-of-the-art radiative transfer modelling based, for the first time, on a set of optical and near-infrared galaxy images. We show that by taking into account near-infrared imaging in the modelling significantly improves the constraints on the retrieved parameters of the dust content. We confirm the result from previous studies that including a young stellar population in the modelling is important to explain the observed stellar energy distribution. However, the discrepancy between the observed and modelled thermal emission at far-infrared wavelengths, the so-called dust energy balance problem, is still present: the model underestimates the observed fluxes by a factor of about two. We compare two different dust models, and find that dust parameters, and thus the spectral energy distribution in the infrared domain, are sensitive to the adopted dust model. In general, the THEMIS model reproduces the observed emission in the infrared wavelength domain better than the popular BARE-GR-S model. Our study of IC 2531 is a pilot case for detailed and uniform radiative transfer modelling of the entire HEROES sample, which will shed more light on the strength and origins of the dust energy balance problem. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.The reduced images (as FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A71

A multidisciplinary approach to trace Asian dust storms from source to sink

NASA Astrophysics Data System (ADS)

Yan, Yan; Sun, Youbin; Ma, Long; Long, Xin

2015-03-01

Tracing the source of dust storm (DS) in mega-cities of northern China currently suffers ambiguities from different approaches including source-sink proxy comparison, air mass back trajectory modeling, and satellite image monitoring. By integrating advantages of all three methods, we present a multidisciplinary approach to trace the provenance of dust fall in Xi'an during the spring season (March to May) of 2012. We collected daily dust fall to calculate dust flux variation, and detected eight DS events with remarkable high flux values based on meteorological comparison and extreme detection algorithm. By combining MODIS images and accompanying real-time air mass back trajectories, we attribute four of them as natural DS events and the other four as anthropogenic DS events, suggesting the importance of natural and anthropogenic processes in supplying long-range transported dust. The primary sources of these DS events were constrained to three possible areas, including the northern Chinese deserts, Taklimakan desert, and Gurbantunggut desert. Proxy comparisons based upon the quartz crystallinity index and oxygen isotope further confirmed the source-to-sink linkage between the natural DS events in Xi'an and the dust emissions from the northern Chinese deserts. The integration of geochemical and meteorological tracing approaches favors the dominant contribution of short-distance transportation of modern dust fall on the Chinese Loess Plateau. Our study shows that the multidisciplinary approach could permit a better source identification of modern dust and should be applied properly for tracing the provenance fluctuations of geological dust deposits.

A Dust Devil Playground

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] Context image for PIA02185 A Dust Devil Playground

Dust Devil activity in this region between Brashear and Ross Craters is very common. Large regions of dust devil tracks surround the south polar region of Mars.

Image information: VIS instrument. Latitude -55.2N, Longitude 244.2E. 17 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Enhancing weak transient signals in SEVIRI false color imagery: Application to dust source detection in southern Africa

NASA Astrophysics Data System (ADS)

Murray, J. E.; Brindley, H. E.; Bryant, R. G.; Russell, J. E.; Jenkins, K. F.; Washington, R.

2016-09-01

A method is described to significantly enhance the signature of dust events using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI). The approach involves the derivation of a composite clear-sky signal for selected channels on an individual time step and pixel basis. These composite signals are subtracted from each observation in the relevant channels to enhance weak transient signals associated with either (a) low levels of dust emission or (b) dust emissions with high salt or low quartz content. Different channel combinations, of the differenced data from the steps above, are then rendered in false color imagery for the purpose of improved identification of dust source locations and activity. We have applied this clear-sky difference (CSD) algorithm over three (globally significant) source regions in southern Africa: the Makgadikgadi Basin, Etosha Pan, and the Namibian and western South African coast. Case study analyses indicate three notable advantages associated with the CSD approach over established image rendering methods: (i) an improved ability to detect dust plumes, (ii) the observation of source activation earlier in the diurnal cycle, and (iii) an improved ability to resolve and pinpoint dust plume source locations.

Improving dust emission characterization in dust models using dynamic high-resolution geomorphic erodibility map

NASA Astrophysics Data System (ADS)

Parajuli, S. P.; Yang, Z.; Kocurek, G.

2013-12-01

Dust is known to affect the earth radiation budget, biogeochemical cycle, precipitation, human health and visibility. Despite the increased research effort, dust emission modeling remains challenging because dust emission is affected by complex geomorphological processes. Existing dust models overestimate dust emission and rely on tuning and a static erodibility factor in order to make simulated results comparable to remote sensing and ground-based observations. In most of current models, dust emission is expressed in terms of threshold friction speed, which ultimately depends mainly upon the percentage clay content and soil moisture. Unfortunately, due to the unavailability of accurate and high resolution input data of the clay content and soil moisture, estimated threshold friction speed commonly does not represent the variability in field condition. In this work, we attempt to improve dust emission characterization by developing a high resolution geomorphic map of the Middle East and North Africa (MENA), which is responsible for more than 50% of global dust emission. We develop this geomorphic map by visually examining high resolution satellite images obtained from Google Earth Pro and ESRI base map. Albeit subjective, our technique is more reliable compared to automatic image classification technique because we incorporate knowledge of geological/geographical setting in identifying dust sources. We hypothesize that the erodibility is unique for different geomorphic landforms and that it can be quantified by the correlation between observed wind speed and satellite retrieved aerosol optical depth (AOD). We classify the study area into several key geomorphological categories with respect to their dust emission potential. Then we quantify their dust emission potential using the correlation between observed wind speed and satellite retrieved AOD. The dynamic, high-resolution geomorphic erodibility map thus prepared will help to reduce the uncertainty in current dust models associated with poor characterization of dust sources. The baseline dust scheme used in this study is the Dust Entrainment and Deposition (DEAD) model, which is also a component of the community land model (CLM). Proposed improvements in the dust emission representation will help to better understand the accurate effect of dust on climate processes.

Ultraviolet Radiative Transfer Modeling of Nearby Galaxies with Extraplanar Dusts

NASA Astrophysics Data System (ADS)

Shinn, Jong-Ho; Seon, Kwang-Il

2015-12-01

In order to examine their relation to the host galaxy, the extraplanar dusts of six nearby galaxies are modeled, employing a three-dimensional Monte Carlo radiative transfer code. The targets are from the highly inclined galaxies that show dust-scattered ultraviolet halos, and the archival Galaxy Evolution Explorer FUV band images were fitted with the model. The observed images are generally well-reproduced by two dust layers and one light source layer, whose vertical and radial distributions have exponential profiles. We obtained several important physical parameters, such as star formation rate (SFRUV), face-on optical depth, and scale-heights. Three galaxies (NGC 891, NGC 3628, and UGC 11794) show clear evidence for the existence of an extraplanar dust layer. However, it is found that the remaining three targets (IC 5249, NGC 24, and NGC 4173) do not necessarily need a thick dust disk to model the ultraviolet (UV) halo, because its contribution is too small and the UV halo may be caused by the wing part of the GALEX point spread function. This indicates that the galaxy samples reported to have UV halos may be contaminated by galaxies with negligible extraplanar (halo) dust. The galaxies showing evidence of an extraplanar dust layer fall within a narrow range on the scatter plots between physical parameters such as SFRUV and extraplanar dust mass. Several mechanisms that could possibly produce the extraplanar dust are discussed. We also found a hint that the extraplanar dust scale-height might not be much different from the polycyclic aromatic hydrocarbon emission characteristic height.

Dust Devils Seen Streaking Across Mars: PART II--They're the Work of the Devil!

NASA Technical Reports Server (NTRS)

2000-01-01

[figure removed for brevity, see original site]

[figure removed for brevity, see original site]

In December 1999, the MOC team finally had an answer! A dust devil, shown in the above left figure, was caught in the act of creating a swirly, dark streak! An eerie sensation washed over the first team members who saw this picture--here was an event on Mars 'caught in the act' just hours before the picture was played back to Earth. A 'smoking gun.'

The first dust devil seen making a streak--located in Promethei Terra (above, left)--was traveling from right (east) to left (west). A columnar shadow was cast by sunlight coming from the upper left. This shadow indicates the true shape of the dust devil. The bright dust devil itself does not look like a column because the picture was taken from a camera looking straight down on it. The dust devil is less than 100 meters (less than 100 yards) wide and the picture covers an area approximately 1.5 by 1.7 kilometers (about 1 by 1 mile).

Dust devils are spinning, columnar vortices of wind that move across the landscape, pick up dust, and look somewhat like miniature tornadoes. Dust devils are a common occurrence in dry and desert landscapes on Earth as well as Mars. They form when the ground heats up during the day, warming the air immediately above the surface. As the warmed air nearest the surface begins to rise, it spins. The spinning column begins to move across the surface and picks up loose dust (if any is present). The dust makes the vortex visible and gives it the 'dust devil' or tornado-like appearance. On Earth, dust devils typically last for only a few minutes.

The fourth picture (above, right) shows a surface in southwestern Terra Sirenum near 63oS, 168oW, that has seen the activity of so many dust devils that it looks like a plate of dark gray spaghetti. This image, taken in early summer during February 2000, covers an area 3 km wide and 30 km long (1.9 by 19 miles). In fact, a dust devil can be seen in the upper right of this image. Like the other pictures shown here, the Terra Sirenum image is illuminated by sunlight from the upper left.

How much dust does Enceladus eject?

NASA Astrophysics Data System (ADS)

Kempf, Sascha; Horanyi, Mihaly; Schmidt, Jürgen; Southworth, Ben

2015-04-01

There is an ongoing argument how much dust per second the ice volcanoes on Saturn's ice moon Enceladus eject. By adjusting their plume model to the dust flux measured by the Cassini dust detector during the close Enceladus flyby in 2005, as well as to the plume brightness in Cassini imaging, Schmidt et al. (2008) obtained a total dust production rate in the plumes of about 5 kg/s. On the other hand, Ingersoll and Ewald (2011) derived a dust production rate of 51 kg/s from photometry of very high phase-angle images of the plume, a method that is sensitive also to particles in the size range of microns and larger. Knowledge of the production rate is essential for estimating the dust to gas mass ratio, which in turn is an important constraint for finding the plume source mechanism. Here we report on numerical simulations of the Enceladus dust plume. We run a large number of dynamical simulations including gravity and Lorentz force to investigate the earliest phase of the ring particle life span. The magnetic field in the vicinity of Enceladus is based on the model by Simon et al. (2012). The evolution of the electrostatic charge carried by the initially uncharged grains is treated self-consistently. Our numerical simulations reproduce dust measurements by the Cassini Cosmic Dust Analyzer (CDA) during Cassini plume traversals as well as the snowfall pattern derived from ISS observations of the Enceladus surface (Schenk et al, 2011, EPSC abstract). Based on our simulation results we are able to draw conclusions about the dust production rate as well as wether the Enceladus dust plume constitutes a dusty plasma.

Metal Evolution and TrAnsport in the Large Magellanic Cloud (METAL): Probing Dust Evolution in Star Forming Galaxies

NASA Astrophysics Data System (ADS)

Roman-Duval

2016-10-01

METAL is a large spectroscopic and imaging program with HST dedicated to the study of dust evolution in the Large Magellanic Cloud (LMC). The program will obtain FUV and NUV medium-resolution spectra of 33 massive stars in the LMC with STIS and COS complementing existing archival data to measure gas-phase and dust-phase (depletion) elemental abundances. With these spectra, we will subsequently directly measure the dust composition and abundance as a function of environment (surface density, radiation field, dynamical conditions, such as the proximity of supernova remnants or expanding HI shells). The depletion information will be complemented with dust UV extinction curves (i.e., the UV opacity of dust grains as a function of wavelength) derived from either archival IUE, or new COS and low-resolution STIS spectra acquired as part of this program. Together, the depletions and extinction curves will constrain how the dust abundance and properties (composition, size distribution) vary with environment at Z=0.5Zo. In parallel to the spectroscopic observations, we will obtain WFC3 NUV-NIR imaging to map dust extinction parameters (AV, RV) in the vicinity of our targets and calibrate the far-infrared (FIR) emissivity of dust. Our observations we will improve the accuracy of dust mass and extinction estimates in the local and high-redshift universe by up to an order of magnitude.METAL will complement a Cycle 23 HST/STIS program (GO-13778) focused on dust evolution in the Small Magellanic Cloud (SMC) at Z=0.2Zo, and previously published depletion studies in the Milky Way (Jenkins et al. 2009) to provide a comprehensive view of dust evolution as a function of metallicity.

Stardust Sample Collection at Wild 2 and Its Preliminary Examination

NASA Technical Reports Server (NTRS)

Tsou, P.; Brownlee, D. E.; Hoerz, F.; Newburn, R. L.; Sandford, S. A.; Sekanina, Z.; Zolensky, M. E.

2004-01-01

The primary objective of STARDUST is to collect coma samples from 81P/Wild 2. This was made on January 2, 2004. Before the encounter three significant model predictions existed for the number and size of samples to be captured. Three investigations during the Wild 2 encounter (Dust Flux Monitor, Comet and Interstellar Dust Analyzer and Dynamic Science) made in situ measurements of the dust. Spectacular images were captured of the Wild 2 nucleus and dust jets. This abstract compares the model predictions with the in situ measurements and Wild 2 images and assesses the likely samples to be returned for analysis on January 15, 2006. To give some lead time for sample analysts to prepare for the analyses of the returned samples, the organization of the Preliminary Examination is presented.

Dust devils as aeolian transport mechanisms in southern Nevada and the Mars Pathfinder landing site

NASA Astrophysics Data System (ADS)

Metzger, Stephen M.

Discovery of dust devils vortices in Mars Pathfinder images by this study is direct evidence of a dust entrainment mechanism at work on Mars. Dust devils on Earth can entrain fine material from crusted as well as unconsolidated surfaces, even when forced-convection wind speeds are below threshold. Terrestrial dust devils are commonly ``squat'' V-shaped vortices lasting several minutes. Well developed vortices consist of an outer cylinder of high rotation (<25 m/s), an Intermediate cylinder of moderate vertical lift (<13 m/s), and a inner cylindrical core of low pressure (<1.5% below ambient pressure) and elevated temperature (up to 20°C above ambient air temperature). Directly sampled dust devils on Earth were found to carry from 30 to over 2000 kg of soil. On average, the Eldorado Valley, NV, experienced 42 observable dust devils per summer day, each lofting over 200 kg for a daily total of 9 metric tonnes from this desert basin. Spectral differencing techniques have enhanced five localized dust plumes against the general haze in Mars Pathfinder images acquired near midday, which are determined to be dust devils. Given interpreted geographic locations relative to the lander, the dust devils are 14 to 79 m wide, 46 to over 350 m tall, and travel over ground at 0.5 to 4.6 m/s. Their dust loading was approximately 7 × 10-5 kg/m3, relative to the general haze of 9 × 10-8 kg/m3. With an estimated vertical dust flux of 0.5 g m-2 s-1, total particulate transport of these Martian dust devils may have ranged from 2.2 kg for a small dust devil lasting 35 s to over 700 kg for a large plume of 400 s duration. Observed characteristics of these plumes are consistent with expectations based on theory and the lessons of terrestrial field studies. The increasingly apparent role of dust devils in the dust aeolian transport cycle may largely explain the continued concentration of the general Martian dust haze and perhaps the Initiation mechanism for global dust storms.

SN 1987A after 18 Years: Mid-Infrared Gemini and Spitzer Observations of the Remnant

NASA Astrophysics Data System (ADS)

Bouchet, Patrice; Dwek, Eli; Danziger, John; Arendt, Richard G.; De Buizer, I. James M.; Park, Sangwook; Suntzeff, Nicholas B.; Kirshner, Robert P.; Challis, Peter

2006-10-01

Using the Gemini South 8 m telescope, we obtained high-resolution 11.7 and 18.3 μm mid-IR images of SN 1987A on day 6526 since the explosion. All the emission arises from the equatorial ring. Nearly contemporaneous spectra obtained at 5-38 μm with the Spitzer Space Telescope show that this is thermal emission from silicate dust that condensed out in the red giant wind of the progenitor star. The dust temperature is 166+18-12 K, and the emitting dust mass is 2.6+2.0-1.4×10-6 Msolar. Comparison of the Gemini 11.7 μm image with Chandra X-ray images, HST UV-optical images, and ATCA radio synchrotron images shows generally good correlation across all wavelengths. If the dust resides in the diffuse X-ray-emitting gas then it is collisionally heated. The IR emission can then be used to derive the plasma temperature and density, which were found to be in good agreement with those inferred from the X-rays. Alternatively, the dust could reside in the dense UV-optical knots and be heated by the radiative shocks that are propagating through the knots. In either case the dust-to-gas mass ratio in the CSM around the supernova is significantly lower than that in the general interstellar medium of the LMC, suggesting either a low condensation efficiency in the wind of the progenitor star or the efficient destruction of the dust by the SN blast wave. Overall, we are witnessing the interaction of the SN blast wave with its surrounding medium, creating an environment that is rapidly evolving at all wavelengths. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under cooperative agreement with the National Science Foundation (NSF) on behalf of the Gemini partnership: the NSF (United States), the Particle Physics and Astronomy research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong Ruobing; Rafikov, Roman; Zhu Zhaohuan

Through detailed radiative transfer modeling, we present a disk+cavity model to simultaneously explain both the spectral energy distribution (SED) and Subaru H-band polarized light imaging for the pre-transitional protoplanetary disk PDS 70. In particular, we are able to match not only the radial dependence but also the absolute scale of the surface brightness of the scattered light. Our disk model has a cavity 65 AU in radius, which is heavily depleted of sub-micron-sized dust grains, and a small residual inner disk that produces a weak but still optically thick near-IR excess in the SED. To explain the contrast of themore » cavity's edge in the Subaru image, a factor of {approx}1000 depletion for the sub-micron-sized dust inside the cavity is required. The total dust mass of the disk may be on the order of 10{sup -4} M {sub Sun }, only weakly constrained due to the lack of long-wavelength observations and the uncertainties in the dust model. The scale height of the sub-micron-sized dust is {approx}6 AU at the cavity edge, and the cavity wall is optically thick in the vertical direction at H-band. PDS 70 is not a member of the class of (pre-)transitional disks identified by Dong et al., whose members only show evidence of the cavity in the millimeter-size dust but not the sub-micron-sized dust in resolved images. The two classes of (pre-)transitional disks may form through different mechanisms, or they may simply be at different evolution stages in the disk-clearing process.« less

Comparative study of the dust emission of 19P/Borrelly (Deep Space 1) and 1P/Halley

USGS Publications Warehouse

Ho, T.-M.; Thomas, N.; Boice, D.C.; Kollein, C.; Soderblom, L.A.

2003-01-01

Images obtained by the Miniature Integrated Camera and Imaging Spectrometer (MICAS) experiment onboard the Deep Space 1 spacecraft which encountered comet 19P/Borrelly on September 22nd 2001 show a dust coma dominated by jets. In particular a major collimated dust jet on the sunward side of the nucleus was observed. Our approach to analyse these features is to integrate the observed intensity in concentric envelopes around the nucleus. The same procedures has been used on the Halley Multicolour Camera images of comet 1P/Halley acquired on March 14th 1986. We are able to show that at Borrelly the dust brightness dependence as a function of radial distance is different to that of Halley. At large distances both comets show constant values as the size of the concentric envelopes increases (as one would expect for force free radial outflow). For Halley the integral decreases as one gets closer to the nucleus. Borrelly shows opposite behaviour. The main cause for Halley's intensity distribution is either high optical thickness or particle fragmentation. For Borrelly, we have constructed a simple model of the brightness distribution near the nucleus. This indicates that the influence of deviations from point source geometry is insufficient to explain the observed steepening of the intensity profile close to the nucleus. Dust acceleration or fragmentation into submicron particles appear to be required. We also estimate the dust production rate of Borrelly with respect to Halley and compare their dust to gas ratios. ?? 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Tendrils of Cold Dust

NASA Image and Video Library

2010-03-17

This three-color combination constructed from ESA Planck two highest frequency channels and an image obtained with the NASA Infrared Astronomical Satellite shows local dust structures within 500 light-years of the sun.

A Dielectric-Filled Waveguide Antenna Element for 3D Imaging Radar in High Temperature and Excessive Dust Conditions.

PubMed

Xu, Ding; Li, Zhiping; Chen, Xianzhong; Wang, Zhengpeng; Wu, Jianhua

2016-08-22

Three-dimensional information of the burden surface in high temperature and excessive dust industrial conditions has been previously hard to obtain. This paper presents a novel microstrip-fed dielectric-filled waveguide antenna element which is resistant to dust and high temperatures. A novel microstrip-to-dielectric-loaded waveguide transition was developed. A cylinder and cuboid composite structure was employed at the terminal of the antenna element, which improved the return loss performance and reduced the size. The proposed antenna element was easily integrated into a T-shape multiple-input multiple-output (MIMO) imaging radar system and tested in both the laboratory environment and real blast furnace environment. The measurement results show that the proposed antenna element works very well in industrial 3D imaging radar.

Late-summer Martian Dust Storm

NASA Technical Reports Server (NTRS)

2008-01-01

This is an image of Mars taken from orbit by the Mars Reconnaissance Orbiter's Mars Color Imager (MARCI). The Red Planet's polar ice-cap is in the middle of the image. Captured in this image is a 37,000 square-kilometer (almost 23,000 miles) dust storm that moved counter-clockwise through the Phoenix landing site on Oct 11, 2008, or Sol 135 of the mission.

Viewing this image as if it were the face of a clock, Phoenix is shown as a small white dot, located at about 10 AM. The storm, which had already passed over the landing site earlier in the day, is located at about 9:30 AM.

Earth Observations taken by the Expedition 15 Crew

NASA Image and Video Library

2007-05-12

ISS015-E-07874 (12 May 2007) --- A major dust storm (center right) along the east side of the Aral Sea, Kazakhstan, is featured in this image photographed by an Expedition 15 crewmember on the International Space Station while passing over central Asia. The white, irregular lines along the bottom of the image are salt and clay deposits on the present coastline. On the spring day when the ISS crew shot the image, winds were blowing from the west (lower left). The gray, puffy appearance is typical of dust clouds, allowing scientists to distinguish dust from fog and smog. The dust in this image is rising from the sea bed of the Aral Sea, from a point close to the middle of the original Aral Sea of 40--50 years ago, then the fourth largest inland sea on Earth. Heavy extraction of water from the main supply river, the Amu Dary'a, has resulted in rapid shrinking of the sea. According to scientists, dust storms have been occurring in the Aral Sea region for thousands of years, but since the drastic shrinking of the sea over the past half-century an important change in dust composition has occurred. The dust now includes fertilizer and pesticide washed into the Sea from the extensive cotton fields of the Amu Dary'a floodplain. Years of liberal application of agricultural chemicals have resulted in concentration of these pollutants on the sea bed. These are now exposed to the wind and transported hundreds of kilometers in a generally easterly direction. Research suggests that the remobilized chemicals are the cause of high rates of many diseases in the populations along the north, east and southern margins of the Aral Sea. This is one of the unintended consequences of the shrinking of the sea, which has made international news for many years due to the loss of the fishing industry and other significant ecological problems.

NASA Galaxy Mission Celebrates Sixth Anniversary

NASA Image and Video Library

2009-04-28

NASA Galaxy Evolution Explorer Mission celebrates its sixth anniversary studying galaxies beyond our Milky Way through its sensitive ultraviolet telescope, the only such far-ultraviolet detector in space. Pictured here, the galaxy NGC598 known as M33. The mission studies the shape, brightness, size and distance of distant galaxies across 10 billion years of cosmic history, giving scientists a wealth of data to help us better understand the origins of the universe. One such object is pictured here, the galaxy NGC598, more commonly known as M33. This image is a blend of the Galaxy Evolution Explorer's M33 image and another taken by NASA's Spitzer Space Telescope. M33, one of our closest galactic neighbors, is about 2.9 million light-years away in the constellation Triangulum, part of what's known as our Local Group of galaxies. Together, the Galaxy Evolution Explorer and Spitzer can see a broad spectrum of sky. Spitzer, for example, can detect mid-infrared radiation from dust that has absorbed young stars' ultraviolet light. That's something the Galaxy Evolution Explorer cannot see. This combined image shows in amazing detail the beautiful and complicated interlacing of the heated dust and young stars. In some regions of M33, dust gathers where there is very little far-ultraviolet light, suggesting that the young stars are obscured or that stars farther away are heating the dust. In some of the outer regions of the galaxy, just the opposite is true: There are plenty of young stars and very little dust. Far-ultraviolet light from young stars glimmers blue, near-ultraviolet light from intermediate age stars glows green, and dust rich in organic molecules burns red. This image is a 3-band composite including far infrared as red. http://photojournal.jpl.nasa.gov/catalog/PIA11998

76 FR 22721 - Notice of Availability of Draft Resource Management Plans and Associated Environmental Impact...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-22

... DEPARTMENT OF THE INTERIOR Bureau of Land Management [LLWYR0000.L16100000.DP0000.LXSS042K0000] Notice of Availability of Draft Resource Management Plans and Associated Environmental Impact Statement for the Bighorn Basin Resource Management Plan Revision Project, Cody and Worland Field Offices...

EVALUATION OF THE RCRA (RESOURCE CONSERVATION AND RECOVERY ACT) EXTRACTION PROCEDURE - LYSIMETER STUDIES WITH MUNICIPAL/INDUSTRIAL WASTES

EPA Science Inventory

A study was initiated to determine the accuracy with which the Extraction Procedures (EP), employed in the regulations promulgated under Section 3001 of the Resource Conservation and Recovery Act (40 CFR 26.124), simulates the leaching an industrial waste would undergo when codis...

76 FR 10583 - Environmental Impacts Statements; Notice of Availability

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-25

... No. 20110048, Draft EIS, DOE, 00, Disposal of Greater-Than-Class C (GTCC) Low-Level Radioactive Waste and GTCC-Like Waste, Proposed Development, Operation, and Long-Term Management of a Disposal Facility... Period Ends: 03/28/2011, Contact: Cody Wheeler 816-389-3739. EIS No. 20110051, Draft EIS, USN, CA, Marine...

NASA's Phoenix Lander on Mars, Nearly a Decade Later

NASA Image and Video Library

2018-02-20

This is one of two images taken nearly a decade apart of NASA's Mars Phoenix Lander and related hardware around the mission's May 25, 2008, landing site on far-northern Mars. By late 2017, dust had obscured much of what was visible two months after the landing. Both images were taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The one with three patches of darker ground -- where landing events removed dust -- was taken on July 20, 2008. It is Fig. 1, an excerpt of HiRISE observation PSP_009290_2485. The one with a more even coating of pale dust throughout the area was taken on Dec. 21, 2017. It is Fig. 2, an excerpt of HiRISE observation ESP_053451_2485. Both cover an area roughly 300 meters wide at 68 degrees north latitude, 234 degrees east longitude, and the two are closely matched in viewing and illumination geometry, from about five Martian years apart in northern hemisphere summers. An animation comparing the two images shows a number of changes between mid-2008 and late 2017. The lander (top) appears darker, and is now covered by dust. The dark spot created by the heat shield impact (right) is brighter, again due to dust deposition. The back shell and parachute (bottom) shows a darker parachute and brighter area of impact disturbance, thanks again to deposits of dust. We also see that the parachute has shifted in the wind, moving to the east. In August 2008, Phoenix completed its three-month mission studying Martian ice, soil and atmosphere. The lander worked for two additional months before reduced sunlight caused energy to become insufficient to keep the lander functioning. The solar-powered robot was not designed to survive through the dark and cold conditions of a Martian arctic winter. An animation and both images are available at https://photojournal.jpl.nasa.gov/catalog/PIA22223

The global regulator CodY is required for the fitness of Bacillus cereus in various laboratory media and certain beverages.

PubMed

Kovács, Ákos T

2016-07-01

The impact of gene mutations on the growth of the cells can be studied using pure cultures. However, the importance of certain proteins and pathways can be also examined via co-culturing wild type and its mutant derivative. Here, the relative fitness of a mutant strain that lacks the global nitrogen regulator, CodY, was examined in Bacillus cereus, a food poisoning Gram-positive bacterium. Fitness measurements revealed that the ΔcodY strain was outcompeted when cocultured with the wild-type ATCC 14579 under various rich laboratory medium, and also when inoculated in certain beverages. In nutrient-poor minimal medium, the ΔcodY mutant had comparable fitness to the wild-type strain. Interestingly, the relative fitness of the ΔcodY strain was antagonistic when it was cultivated in apple or orange juices due to unknown properties of these beverages, highlighting the importance of chemical composition of the test medium during the bacterial fitness measurements. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Two-component Thermal Dust Emission Model: Application to the Planck HFI Maps

NASA Astrophysics Data System (ADS)

Meisner, Aaron M.; Finkbeiner, Douglas P.

2014-06-01

We present full-sky, 6.1 arcminute resolution maps of dust optical depth and temperature derived by fitting the Finkbeiner et al. (1999) two-component dust emission model to the Planck HFI and IRAS 100 micron maps. This parametrization of the far infrared thermal dust SED as the sum of two modified blackbodies serves as an important alternative to the commonly adopted single modified blackbody dust emission model. We expect our Planck-based maps of dust temperature and optical depth to form the basis for a next-generation, high-resolution extinction map which will additionally incorporate small-scale detail from WISE imaging.

Using NASA EOS in the Arabian and Saharan Deserts to Examine Dust Particle Size and Spectral Signature of Aerosols

NASA Astrophysics Data System (ADS)

Brenton, J. C.; Keeton, T.; Barrick, B.; Cowart, K.; Cooksey, K.; Florence, V.; Herdy, C.; Luvall, J. C.; Vasquez, S.

2012-12-01

Exposure to high concentrations of airborne particulate matter can have adverse effects on the human respiratory system. Ground-based studies conducted in Iraq have revealed the presence of potential human pathogens in airborne dust. According to the Environmental Protection Agency (EPA), airborne particulate matter below 2.5μm (PM2.5) can cause long-term damage to the human respiratory system. Given the relatively high incidence of new-onset respiratory disorders experienced by US service members deployed to Iraq, this research offers a new glimpse into how satellite remote sensing can be applied to questions related to human health. NASA's Earth Observing System (EOS) can be used to determine spectral characteristics of dust particles, the depth of dust plumes, as well as dust particle sizes. Comparing dust particle size from the Sahara and Arabian Deserts gives insight into the composition and atmospheric transport characteristics of dust from each desert. With the use of NASA SeaWiFS DeepBlue Aerosol, dust particle sizes were estimated using Angström exponent. Brightness Temperature Difference (BTD) equation was used to determine the distribution of particle sizes, the area of the dust storm, and whether silicate minerals were present in the dust. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra satellite was utilized in calculating BTD. Minimal research has been conducted on the spectral characteristics of airborne dust in the Arabian and Sahara Deserts. Mineral composition of a dust storm that occurred 17 April 2008 near Baghdad was determined using imaging spectrometer data from the Jet Propulsion Laboratory Spectral Library and EO-1 Hyperion data. Mineralogy of this dust storm was subsequently compared to that of a dust storm that occurred over the Bodélé Depression in the Sahara Desert on 7 June 2003.

Earth Observation

NASA Image and Video Library

2012-07-15

ISS032-E-008976 (15 July 2012) --- Saharan dust reaching the Americas is featured in this image photographed by an Expedition 32 crew member on the International Space Station. Weather satellites frequently document major dust palls blowing from the Sahara Desert westward from Africa out into the tropical Atlantic Ocean. Space station crew members frequently see these Saharan dust masses as very widespread atmospheric haze. Dust palls blowing from Africa can be transported right across the Atlantic Ocean. It takes about a week to reach either North America (in northern hemisphere summer) or South America (in northern hemisphere winter). This puts the Caribbean basin on the receiving end of many of these events. Recently, researchers have linked Saharan dust to coral disease, allergic reactions in humans, and red tides. The margin of the hazy air in this image reaches as far as Haiti (top center) and the nearby Turks and Caicos Islands (top left) ? but the eastern tip of Cuba in the foreground remains in the clear air.

Mapping erodibility in dust source regions based on geomorphology, meteorology, and remote sensing

NASA Astrophysics Data System (ADS)

Parajuli, Sagar Prasad; Yang, Zong-Liang; Kocurek, Gary

2014-09-01

Mineral dust in the atmosphere has implications for Earth's radiation budget, biogeochemical cycles, hydrological cycles, human health, and visibility. Currently, the simulated vertical mass flux of dust differs greatly among the existing dust models. While most of the models utilize an erodibility factor to characterize dust sources, this factor is assumed to be static, without sufficient characterization of the highly heterogeneous and dynamic nature of dust source regions. We present a high-resolution land cover map of the Middle East and North Africa (MENA) in which the terrain is classified by visually examining satellite images obtained from Google Earth Professional and Environmental Systems Research Institute Basemap. We show that the correlation between surface wind speed and Moderate Resolution Imaging Spectroradiometer deep blue aerosol optical depth (AOD) can be used as a proxy for erodibility, which satisfactorily represents the spatiotemporal distribution of soil-derived dust sources. This method also identifies agricultural dust sources and eliminates the satellite-observed dust component that arises from long-range transport, pollution, and biomass burning. The erodible land cover of the MENA region is grouped into nine categories: (1) bedrock: with sediment, (2) sand deposit, (3) sand deposit: on bedrock, (4) sand deposit: stabilized, (5) agricultural and urban area, (6) fluvial system, (7) stony surface, (8) playa/sabkha, and (9) savanna/grassland. Our results indicate that erodibility is linked to the land cover type and has regional variation. An improved land cover map, which explicitly accounts for sediment supply, availability, and transport capacity, may be necessary to represent the highly dynamic nature of dust sources in climate models.

Dust Transport and Deposition Observed from the Terra-Moderate Image Spectrometer (MODIS) Space Observations

NASA Technical Reports Server (NTRS)

Kaufman, Y.

2004-01-01

Meteorological observations, in situ data and satellite images of dust episodes were used already in the 1970s to estimate that 100 tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but deteriorates air quality and caries pathogens as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport and deposition. The Terra spacecraft launched at the dawn of the last millennium provides first systematic well calibrated multispectral measurements from the MODIS instrument, for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and evaluate the African dust column concentration, transport and deposition. We found that 230 plus or minus 80 tg of dust are transported annually from Africa to the Atlantic Ocean, 30 tg return to Africa and Europe, 70 tg reach the Caribbean, 45 tg fertilize the Amazon Basin, 4 times as previous estimates thus explaining a paradox regarding the source of nutrition to the Amazon forest, and 120 plus or minus 40 tg are deposited in the Atlantic Ocean. The results are compared favorably with dust transport models for particle radius less than or equal to 12 microns. This study is a first example of quantitative use of MODIS aerosol for a geophysical study.

Dust Storm in Southern California

NASA Technical Reports Server (NTRS)

2007-01-01

Along historic Route 66, just southeast of the little town of Amboy, California, lies a dried-up lake. Dry lakebeds are good sources of two things: salt and dust. In this image, the now-parched Bristol Lake offers up both. On April 12, 2007, dust storms menaced the area around Amboy. To the northwest, near Newberry Springs, California, dust hampered visibility and led to a multi-car collision on Interstate 40, killing two people and injuring several others. The same day, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of a dust storm in the dry remains of Bristol Lake. Many small dust clouds boil up from the ground surface, casting their shadows to the northwest. A bright white cloud floating over the dust also throws its shadow onto the ground below. East of the dust storm are salt works that stand out from the surrounding landscape thanks to their straight lines and sharp angles. Dark ground surfaces alternate with mined white salt in a network of stripes. When lakes evaporate, chemicals that had been dissolved in the water stay behind, making dry lake beds an ideal place to find heavy concentrations of minerals, including salt. Besides the salt works, something else appears in stark contrast to this arid place. Lush green fields of irrigated crops appear in the east. Besides their color, their orderly arrangement reveals their human-made origin.

Measurements of Martian dust devil winds with HiRISE

USGS Publications Warehouse

Choi, D.S.; Dundas, C.M.

2011-01-01

We report wind measurements within Martian dust devils observed in plan view from the High Resolution Imaging Science Experiment (HiRISE) orbiting Mars. The central color swath of the HiRISE instrument has three separate charge-coupled devices (CCDs) and color filters that observe the surface in rapid cadence. Active features, such as dust devils, appear in motion when observed by this region of the instrument. Our image animations reveal clear circulatory motion within dust devils that is separate from their translational motion across the Martian surface. Both manual and automated tracking of dust devil clouds reveal tangential winds that approach 20-30 m s -1 in some cases. These winds are sufficient to induce a ???1% decrease in atmospheric pressure within the dust devil core relative to ambient, facilitating dust lifting by reducing the threshold wind speed for particle elevation. Finally, radial velocity profiles constructed from our automated measurements test the Rankine vortex model for dust devil structure. Our profiles successfully reveal the solid body rotation component in the interior, but fail to conclusively illuminate the profile in the outer regions of the vortex. One profile provides evidence for a velocity decrease as a function of r -1/2, instead of r -1, suggestive of surface friction effects. However, other profiles do not support this observation, or do not contain enough measurements to produce meaningful insights. Copyright 2011 by the American Geophysical Union.

Dust Devil Art

NASA Technical Reports Server (NTRS)

2005-01-01

12 December 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark squiggles and streaks created by passing spring and summer dust devils near Pallacopas Vallis in the martian southern hemisphere.

Location near: 53.9oS, 17.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

Tropical Atlantic Dust and Smoke Aerosol Variations Related to the Madden-Julian Oscillation in MODIS and MISR Observations

NASA Technical Reports Server (NTRS)

Guo, Yanjuan; Tian, Baijun; Kahn, Ralph A.; Kalashnikova, Olga; Wong, Sun; Waliser, Duane E.

2013-01-01

In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) fine mode fraction and Multi-angle Imaging SpectroRadiometer (MISR) nonspherical fraction data are used to derive dust and smoke aerosol optical thickness (T(sub dust) and T(sub smoke)) over the tropical Atlantic in a complementary way: due to its wider swath, MODIS has 3-4 times greater sampling than MISR, but MISR dust discrimination is based on particle shape retrievals, whereas an empirical scheme is used for MODIS. MODIS and MISR show very similar dust and smoke winter climatologies. T(sub dust) is the dominant aerosol component over the tropical Atlantic, accounting for 40-70 percent of the total aerosol optical thickness (AOT), whereas T(sub smoke) is significantly smaller than T(sub dust). The consistency and high correlation between these climatologies and their daily variations lends confidence to their use for investigating the relative dust and smoke contributions to the total AOT variation associated with the Madden-Julian Oscillation (MJO). The temporal evolution and spatial patterns of the tdus anomalies associated with the MJO are consistent between MODIS and MISR: the magnitude of MJO-realted T(sub dust) anomalies is comparable to or even larger than that of the total T, while the T(sub smoke) anomaly represents about 15 percent compared to the total, which is quite different from their relative magnitudes to the total T on the climatological time scale. This suggests that dust and smoke are not influenced by the MJO in the same way. Based on correlation analysis, dust is strongly influenced by the MJO-modulated trade wind and precipitation anomalies, and can last as long as one MJO phase, whereas smoke is less affected.

Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068

NASA Astrophysics Data System (ADS)

Lopez-Rodriguez, E.; Packham, C.; Roche, P. F.; Alonso-Herrero, A.; Díaz-Santos, T.; Nikutta, R.; González-Martín, O.; Álvarez, C. A.; Esquej, P.; Espinosa, J. M. Rodríguez; Perlman, E.; Ramos Almeida, C.; Telesco, C. M.

2016-06-01

We present subarcsecond 7.5-13 μm imaging- and spectro-polarimetric observations of NGC 1068 using CanariCam on the 10.4-m Gran Telescopio CANARIAS. At all wavelengths, we find: (1) A 90 × 60 pc extended polarized feature in the northern ionization cone, with a uniform ˜44° polarization angle. Its polarization arises from dust and gas emission in the ionization cone, heated by the active nucleus and jet, and further extinguished by aligned dust grains in the host galaxy. The polarization spectrum of the jet-molecular cloud interaction at ˜24 pc from the core is highly polarized, and does not show a silicate feature, suggesting that the dust grains are different from those in the interstellar medium. (2) A southern polarized feature at ˜9.6 pc from the core. Its polarization arises from a dust emission component extinguished by a large concentration of dust in the galaxy disc. We cannot distinguish between dust emission from magnetically aligned dust grains directly heated by the jet close to the core, and aligned dust grains in the dusty obscuring material surrounding the central engine. Silicate-like grains reproduce the polarized dust emission in this feature, suggesting different dust compositions in both ionization cones. (3) An upper limit of polarization degree of 0.3 per cent in the core. Based on our polarization model, the expected polarization of the obscuring dusty material is ≲0.1 per cent in the 8-13 μm wavelength range. This low polarization may be arising from the passage of radiation through aligned dust grains in the shielded edges of the clumps.

COBE'S INFRARED VIEW OF THE UNIVERSE

NASA Technical Reports Server (NTRS)

2002-01-01

These three pictures are maps of the full sky as seen in infrared light. The top two are composite images taken in wavelengths of 60, 100, and 240 micrometers. The 60-micrometer brightness is shown in blue, the 100- micrometer brightness in green, and the 240-micrometer brightness in red. The bottom image shows just the 240-micrometer brightness after foreground light from the solar system and Galaxy has been removed. The images were compiled from data taken between December 1989 and September 1990 by the Diffuse Infrared Background Experiment (DIRBE) on board NASA's Cosmic Background Explorer (COBE). They illustrate the steps scientists used to find the cosmic infrared background, which is a radiative fossil containing cumulative starlight which now appears in the infrared due to the cosmic redshift and by absorption and re-emission by dust in the universe since the Big Bang. The top picture represents the brightness of the full sky as seen in infrared light. The bright yellow-orange line across the center of the image arises from interstellar dust in the plane of our Milky Way Galaxy, with the center of the Galaxy at the center of the image. The red color above and below this line shows additional wispy clouds of interstellar dust. The blue S-shaped color arises from interplanetary dust in the solar system. The middle picture represents a view of the sky after the foreground glow of the solar system dust has been extracted. This image is dominated by emission from interstellar dust in the Milky Way Galaxy. The two bright objects in the center of the lower right quadrant are nearby galaxies, the Large and Small Magellanic Clouds. After the infrared light from our solar system and galaxy has been removed, what remains is a uniform cosmic infrared background. The line across the center is an artifact from removal of galactic light. The DIRBE team reports detection of this cosmic background light also at 140 micrometers, and has set limits to its brightness at eight other infrared wavelengths from 1.25 to 100 micrometers. Credits: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA's Office of Space Science

Optical image of a cometary nucleus: 1980 flyby of Comet Encke

NASA Technical Reports Server (NTRS)

Wells, W. C.; Benson, R. S.; Anderson, A. D.; Gal, G.

1974-01-01

The feasibility was investigated of obtaining optical images of a cometary nucleus via a flyby of Comet Encke. A physical model of the dust cloud surrounding the nucleus was developed by using available physical data and theoretical knowledge of cometary physics. Using this model and a Mie scattering code, calculations were made of the absolute surface brightness of the dust in the line of sight of the on-board camera and the relative surface brightness of the dust compared to the nucleus. The brightness was calculated as a function of heliocentric distance and for different phase angles (sun-comet-spacecraft angle).

Inference of dust opacities for the 1977 Martian great dust storms from Viking Lander 1 pressure data

NASA Technical Reports Server (NTRS)

Zurek, R. W.

1981-01-01

The tidal heating components for the dusty Martian atmosphere are computed based on dust optical parameters estimated from Viking Lander imaging data, and used to compute the variation of the tidal surface pressure components at the Viking Lander sites as a function of season and the total vertical extinction optical depth of the atmosphere. An atmospheric tidal model is used which is based on the inviscid, hydrostatic primitive equations linearized about a motionless basic state the temperature of which varies only with height, and the profiles of the tidal forcing components are computed using a delta-Eddington approximation to the radiative transfer equations. Comparison of the model results with the observed variations of surface pressure and overhead dust opacity at the Viking Lander 1 site reveal that the dust opacities and optical parameters derived from imaging data are roughly representative of the global dust haze necessary to reproduce the observed surface pressure amplitudes, with the exception of the model-inferred asymmetry parameter, which is smaller during the onset of a great storm. The observed preferential enhancement of the semidiurnal tide with respect to the diurnal tide during dust storm onset is shown to be due primarily to the elevation of the tidal heating source in a very dusty atmosphere.

Establishing Extreme Dynamic Range with JWST: Decoding Smoke Signals in the Glare of a Wolf-Rayet Binary

NASA Astrophysics Data System (ADS)

Lau, Ryan; Hankins, M.; Kasliwal, M.; Sivaramakrishnan, A.; Thatte, D.

2017-11-01

Dust is a key ingredient in the formation of stars and planets. However, the dominant channels of dust production throughout cosmic time are still unclear. With its unprecedented sensitivity and spatial resolution in the mid-IR, the James Webb Space Telescope (JWST) is the ideal platform to address this issue by investigating the dust abundance, composition, and production rates of various dusty sources. In particular, colliding-wind Wolf-Rayet (WR) binaries are efficient dust producers in the local Universe, and likely existed in the earliest galaxies. To study these interesting objects, we propose JWST observations of the archetypal colliding-wind binary WR 140 to study its dust composition, abundance, and formation mechanisms. We will utilize two key JWST observing modes with the medium resolution spectrometer (MRS) on the Mid-Infrared Instrument (MIRI) and the Aperture Masking Interferometry (AMI) mode with the Near Infrared Imager and Slitless Spectrograph (NIRISS). Our proposed observations will yield high impact scientific results on the dust forming properties WR binaries, and establish a benchmark for key observing modes for imaging bright sources with faint extended emission. This will be valuable in various astrophysical contexts including mass-loss from evolved stars, dusty tori around active galactic nuclei, and protoplanetary disks. We are committed to designing and delivering science-enabling products for the JWST community that address technical issues such as bright source artifacts that will limit the maximum achievable image contrast.

Effects of dust on forest tree health in Zagros oak forests.

PubMed

Moradi, A; Taheri Abkenar, K; Afshar Mohammadian, M; Shabanian, N

2017-10-10

Dust is one of the most devastating factors for the environment threatening all animal and plant species. In many regions, the ecological and economic impact of microdust on scarce species is critical. In the western region of Iran, the Zagros forests have been exposed to dust storms for many years. In this study, the effect of dust on oak trees, the most important trees of Zagros forests, is investigated. For this purpose, 3-year-old seedlings of three species of oak trees under natural conditions were exposed to dust during spring and summer months. Seedlings were divided into two groups; one group was assigned as dust treatment and the other as control that the control group washed regularly to remove dust. Anatomical characteristics of leaves and dust deposits on leaves during the study period were examined by scanning electron microscope (SEM). The rate of photosynthesis and gas exchange in control and treated plants was examined by IRGA, LCI. SEM images showed that stomata structure, trichome density, and epicuticular waxes of leaves are different in all three species. This difference in micromorphology of species influences the effects of dust deposited on the leaves. A comparison of leaf species images in control and dust treatment showed that in dust treatment the percentage of stomata blocked by dust in three species (per unit area) of Quercus infectoria, Q. libni, and Q. brantii were 61/6, 48/4, and 38/1%, respectively. The results of leaf gas exchange investigation indicated that stomatal occlusion by dust had a negative impact on the examined parameters of three oak species (P ≤ 0.01). Thus, gas exchange and photosynthetic rates of the treated species were significantly reduced. The results of both parts of the study showed the vulnerability of the three species to dust as Q. infectoria > Q. libni > Q. brantii. Therefore, based on these findings, dust can disrupt the physiological activities of the studied species and the continuation of the exposure to dust will accelerate the process of destruction of these forests.

NICMOS PEERS THROUGH DUST TO REVEAL YOUNG STELLAR DISKS

NASA Technical Reports Server (NTRS)

2002-01-01

The following images were taken by NASA Hubble Space Telescope's Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). All of the objects are extremely young stars, 450 light-years away in the constellation Taurus. Most of the nebulae represent small dust particles around the stars, which are seen because they are reflecting starlight. In the color-coding, regions of greatest dust concentration appear red. All photo credits: D. Padgett (IPAC/Caltech), W. Brandner (IPAC), K. Stapelfeldt (JPL) and NASA [Top left]: CoKu Tau/1. This image shows a newborn binary star system, CoKu Tau/1, lying at the center of four 'wings' of light extending as much as 75 billion miles from the pair. The 'wings' outline the edges of a region in the stars' dusty surroundings, which have been cleared by outflowing gas. A thin, dark lane extends to the left and to right of the binary, suggesting that a disk or ring of dusty material encircles the two young stars. [Top center]: DG Tau B - An excellent example of the complementary nature of Hubble's instruments may be found by comparing the infrared NICMOS image of DG Tau B to the visible-light Wide Field and Planetary Camera 2 (WFPC2) image of the same object. WFPC2 highlights the jet emerging from the system, while NICMOS penetrates some of the dust near the star to more clearly outline the 50 billion-mile-long dust lane (the horizontal dark band, which indicates the presence of a large disk forming around the infant star). The young star itself appears as the bright red spot at the corner of the V-shaped nebula. [Top right]: Haro 6-5B - This image of the young star Haro 6-5B shows two bright regions separated by a dark lane. As seen in the WFPC2 image of the same object, the bright regions represent starlight reflecting from the upper and lower surfaces of the disk, which is thicker at its edges than its center. However, the infrared view reveals the young star just above the dust lane. [Bottom left]: I04016 - A very young star still deep within the dusty cocoon from which it formed is shown in this image of IRAS 04016+2610. The star is visible as a bright reddish spot at the base of a bowl-shaped nebula about 100 billion miles across at the widest point. The nebula arises from dusty material falling onto a forming circumstellar disk, seen as a partial dark band to the left of the star. The necklace of bright spots above the star is an image artifact. [Bottom center]: I04248 - In this image of IRAS 04248+2612, the infrared eyes of NICMOS peer through a dusty cloud to reveal a double-star system in formation. A nebula extends at least 65 billion miles in opposite directions from the twin stars, and is illuminated by them. This nebula was formed from material ejected by the young star system. The apparent 'pinching' of this nebula close to the binary suggests that a ring or disk of dust and gas surrounds the two stars. [Bottom right]: I04302 - This image shows IRAS 04302+2247, a star hidden from direct view and seen only by the nebula it illuminates. Dividing the nebula in two is a dense, edge-on disk of dust and gas which appears as the thick, dark band crossing the center of the image. The disk has a diameter of 80 billion miles (15 times the diameter of Neptune's orbit), and has a mass comparable to the Solar Nebula, which gave birth to our planetary system. Dark clouds and bright wisps above and below the disk suggest that it is still building up from infalling dust and gas.

Constraints on Circumstellar Dust Grain Sizes from High Spatial Resolution Observations in the Thermal Infrared

NASA Technical Reports Server (NTRS)

Bloemhof, E. E.; Danen, R. M.; Gwinn, C. R.

1996-01-01

We describe how high spatial resolution imaging of circumstellar dust at a wavelength of about 10 micron, combined with knowledge of the source spectral energy distribution, can yield useful information about the sizes of the individual dust grains responsible for the infrared emission. Much can be learned even when only upper limits to source size are available. In parallel with high-resolution single-telescope imaging that may resolve the more extended mid-infrared sources, we plan to apply these less direct techniques to interpretation of future observations from two-element optical interferometers, where quite general arguments may be made despite only crude imaging capability. Results to date indicate a tendency for circumstellar grain sizes to be rather large compared to the Mathis-Rumpl-Nordsieck size distribution traditionally thought to characterize dust in the general interstellar medium. This may mean that processing of grains after their initial formation and ejection from circumstellar atmospheres adjusts their size distribution to the ISM curve; further mid-infrared observations of grains in various environments would help to confirm this conjecture.

Stormy Clouds of Star Birth

NASA Technical Reports Server (NTRS)

2004-01-01

Hidden behind a shroud of dust in the constellation Cygnus is an exceptionally bright source of radio emission called DR21. Visible light images reveal no trace of what is happening in this region because of heavy dust obscuration. In fact, visible light is attenuated in DR21 by a factor of more than 10,000,000,000,000,000,000,000,000,000, 000,000,000,000 (ten thousand trillion heptillion).

New images from NASA's Spitzer Space Telescope allow us to peek behind the cosmic veil and pinpoint one of the most massive natal stars yet seen in our Milky Way galaxy. The never-before-seen star is 100,000 times as bright as the Sun. Also revealed for the first time is a powerful outflow of hot gas emanating from this star and bursting through a giant molecular cloud.

This image shows a 24-micron image mosaic, obtained with the Multiband Imaging Photometer aboard Spitzer (MIPS). This image maps the cooler infrared emission from interstellar dust found throughout the interstellar medium. The DR21 complex is clearly seen near the center of the strip, which covers about twice the area of the IRAC image.

Perhaps the most fascinating feature in this image is a long and shadowy linear filament extending towards the 10 o'clock position of DR21. This jet of cold and dense gas, nearly 50 light-years in extent, appears in silhouette against a warmer background. This filament is too long and massive to be a stellar jet and may have formed from a pre-existing molecular cloud core sculpted by DR21's strong winds. Regardless of its true nature, this jet and the numerous other arcs and wisps of cool dust signify the interstellar turbulence normally unseen by the human eye.

Twilight at Gusev

NASA Technical Reports Server (NTRS)

2005-01-01

Here is the martian twilight sky at Gusev crater, as imaged by the panoramic camera on NASA's Mars Exploration Rover Spirit around 6:20 in the evening of the rover's 464th martian day, or sol (April 23, 2005). Spirit was commanded to stay awake briefly after sending that sol's data to Mars Odyssey at sunset. This small panorama of the western sky was obtained using camera's 750-nanometer, 530-nanometer and 430-nanometer color filters. This filter combination allows false color images to be generated that are similar to what a human would see, but with the colors exaggerated. In this image, the bluish glow in the sky above where the Sun had just set would be visible to us if we were there, but the redness of the sky farther from the sunset is exaggerated compared to the daytime colors of the martian sky.

These kinds of images are beautiful and evocative, but they also have important scientific purposes. Specifically, twilight images are occasionally acquired by the science team to determine how high into the atmosphere the martian dust extends, and to look for dust or ice clouds. Other images have shown that the twilight glow remains visible, but increasingly fainter, for up to two hours before sunrise or after sunset. The long martian twilight compared to Earth's is caused by sunlight scattered around to the night side of the planet by abundant high altitude dust. Similar long twilights or extra-colorful sunrises and sunsets sometimes occur on Earth when tiny dust grains that are erupted from powerful volcanoes scatter light high in the atmosphere. These kinds of twilight images are also more sensitive to faint cloud structures, though none were detected when these images were acquired. Clouds have been rare at Gusev crater during Spirit's 16-month mission so far.

GT1_mbaes_1: HERschel Observations of Edge-on Spirals (HEROES)

NASA Astrophysics Data System (ADS)

Baes, M.

2010-03-01

We propose to use PACS and SPIRE to map the dust distribution in a sample of seven large edge-on spiral galaxies with regular dust lanes. We will look for the presence of cold dust at large galactocentric radii and investigate the link between dust, gas and metallicity as a function of radius. We will also constrain the vertical distribution of the dust and particularly look for dust emission at large heights above the plane of the galaxies. We will compare the observed Herschel maps with simulated maps resulting from detailed radiative transfer models based on optical and near-infrared images. This will enable us to investigate whether we can confirm the existence of a dust energy balance problem suggested by previous observations (the dust seen in absorption in optical maps underestimates the dust seen in emission) and investigate possible ways to alleviate this potential problem.

Dust Devils Whip by Spirit

NASA Technical Reports Server (NTRS)

2007-01-01

On sol 1120 (February 26, 2007), the navigation camera aboard NASA's Mars Exploration Rover Spirit captured one of the best dust devils it's seen in its three-plus year mission. The series of navigation camera images were put together to make a dust devil movie.

The dust devil column is clearly defined and is clearly bent in the down wind direction. Near the end of the movie, the base of the dust devil becomes much wider. The atmospheric science team thinks that this is because the dust devil encountered some sand and therefore produced a 'saltation skirt,' an apron of material that is thrown out of the dust devil because it is too large to be carried up into suspension.

Also near the end of the movie the dust devil seems to move faster across the surface. This is because Spirit began taking pictures less frequently, and not because the dust devil sped up.

How MIDAS improved our understanding of micrometre-sized cometary dust

NASA Astrophysics Data System (ADS)

Mannel, T.; Bentley, M. S.; Boakes, P.; Jeszenszky, H.; Levasseur-Regourd, A. C.; Schmied, R.; Torkar, K.

2017-09-01

The MIDAS atomic force microscope on the Rosetta orbiter was an instrument developed to investigate, for the first time, the morphology of nearly unaltered cometary dust. It acquired the 3D topography of about 1 - 50 µm sized dust particles with resolutions down to a few nanometres. These images showed the agglomerate character of the dust and confirmed that the smallest subunit sizes were less than 100 nm. MIDAS acquired the first direct proof of a fractal dust particle, opening a new approach to investigate the history of our early Solar System and of comets.

A Dielectric-Filled Waveguide Antenna Element for 3D Imaging Radar in High Temperature and Excessive Dust Conditions

PubMed Central

Xu, Ding; Li, Zhiping; Chen, Xianzhong; Wang, Zhengpeng; Wu, Jianhua

2016-01-01

Three-dimensional information of the burden surface in high temperature and excessive dust industrial conditions has been previously hard to obtain. This paper presents a novel microstrip-fed dielectric-filled waveguide antenna element which is resistant to dust and high temperatures. A novel microstrip-to-dielectric-loaded waveguide transition was developed. A cylinder and cuboid composite structure was employed at the terminal of the antenna element, which improved the return loss performance and reduced the size. The proposed antenna element was easily integrated into a T-shape multiple-input multiple-output (MIMO) imaging radar system and tested in both the laboratory environment and real blast furnace environment. The measurement results show that the proposed antenna element works very well in industrial 3D imaging radar. PMID:27556469

2018 Giant Dust Storm on Mars

NASA Image and Video Library

2018-06-13

This set of images from NASA's Mars Reconnaissance Orbiter (MRO) shows a fierce, giant dust storm is kicking up on Mars, with rovers on the surface indicated as icons. The spread of the storm can be seen in the salmon-colored overlay. These images from MRO's Mars Color Imager start from May 31, when the dust event was first detected, and go through June 11, 2018. MRO creates global maps of Mars but roll maneuvers for targeted observations produce gaps in the coverage, which appear as black gores in the maps. On some days there are data drops where partial or full orbits of coverage are missing. Green and purple observed in the south polar region indicate saturated pixels. Latitude is indicated along the vertical axis. Longitude is indicated along the horizontal axis. https://photojournal.jpl.nasa.gov/catalog/PIA22519

Churned-Up Rocky Debris and Dust (False Color)

NASA Technical Reports Server (NTRS)

2005-01-01

NASA's Mars Exploration Rover Spirit has been analyzing sulfur-rich rocks and surface materials in the 'Columbia Hills' in Gusev Crater on Mars. This image shows rocky debris and dust, which planetary scientists call 'regolith' or 'soil,' that has been churned up by the rover wheels. This 40-centimeter-wide (16-inch-wide) patch of churned-up dirt, nicknamed 'Paso Robles,' contains brighter patches measured to be high in sulfur by Spirit's alpha particle X-ray Spectrometer. Spirit's panoramic camera took this false-color image on martian day, or sol, 400 (Feb. 16, 2005), using filters at wavelengths of 750, 530, and 430 nanometers. Darker red hues in the image correspond to greater concentrations of oxidized soil and dust. Whiter and bluer hues correspond to sulfur-rich deposits that are not as heavily coated with soils or are not as highly oxidized.

NICMOS PEELS AWAY LAYERS OF DUST TO SHOW INNER REGION OF DUSTY NEBULA

NASA Technical Reports Server (NTRS)

2002-01-01

The revived Near Infrared Camera and Multi-Object Spectrometer (NICMOS) aboard NASA's Hubble Space Telescope has penetrated layers of dust in a star-forming cloud to uncover a dense, craggy edifice of dust and gas . This region is called the Cone Nebula (NGC 2264), so named because, in ground-based images, it has a conical shape. NICMOS enables the Hubble telescope to see in near-infrared wavelengths of light, so that it can penetrate the dust that obscures the nebula's inner regions. But the Cone is so dense that even the near-infared 'eyes' of NICMOS can't penetrate all the way through it. The image shows the upper 0.5 light-years of the nebula. The entire nebula is 7 light-years long. The Cone resides in a turbulent star-forming region, located 2,500 light-years away in the constellation Monoceros. Radiation from hot, young stars [located beyond the top of the image] has slowly eroded the nebula over millions of years. Ultraviolet light heats the edges of the dark cloud, releasing gas into the relatively empty region of surrounding space. NICMOS has peeled away the outer layers of dust to reveal even denser dust. The denser regions give the nebula a more three-dimensional structure than can be seen in the visible-light picture at left, taken by the Advanced Camera for Surveys aboard the Hubble telescope. In peering through the dusty facade to the nebula's inner regions, NICMOS has unmasked several stars [yellow dots at upper right]. Astronomers don't know whether these stars are behind the dusty nebula or embedded in it. The four bright stars lined up on the left are in front of the nebula. The human eye cannot see infrared light, so colors have been assigned to correspond with near-infrared wavelengths. The blue light represents shorter near-infrared wavelengths and the red light corresponds to longer wavelengths. The NICMOS color composite image was made by combining photographs taken in J-band, H-band, and Paschen-alpha filters. The NICMOS images were taken on May 11, 2002. Credits for NICMOS image: NASA, the NICMOS Group (STScI, ESA), and the NICMOS Science Team (University of Arizona) Credits for ACS image: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA

Analysis of land surface and synoptic conditions during dust storm events in the Middle East via a new high resolution inventory of mineral dust derived from SEVIRI.

NASA Astrophysics Data System (ADS)

Hennen, Mark

2017-04-01

This paper provides the most up-to-date dust climatology for the Middle East, presenting a new high resolution inventory of over 27,000 dust emission events observed over the Middle East in 2006 - 2013. The inventory was derived from the dust RGB product of the Spinning Enhanced Visual and InfraRed Imager (SEVIRI) on-board Meteosat's second generation satellite (MSG). Mineral dust emissions were derived from visual inspection of the SEVIRI scenes which have 4-5 km2 spatial and 15-minute temporal resolution. The location of every emission event was recorded in a database, along with time and trajectory of dust movement. This is an improvement on previous studies, which derive dust source areas from the daily observations of Aerosol Optical Depth whose maxima do not necessarily coincide with sources of emissions and produces more accurate information on the location of the key dust sources in the region. Results showed that dust sources are constrained to relatively small areas, with 21% of dust emission generated from just 0.9% of total surface area of the Middle East, mainly from eight source regions including the Tigris-Euphrates flood plains of Iraq and Syria, Western and Northern Saudi Arabia and the Sistan Basin in Eastern Iran. The Tigris-Euphrates flood plain was the most active dust region, producing 41% of all dust events with a peak activity in 2009. The southern areas of the Arabian Peninsula recorded very few dust emission observations, in contrast to many previous studies which do not use such high temporal resolution data. The activation and frequency of dust emissions are characterised by strong seasonality developing in response to specific synoptic conditions. To characterise synoptic conditions conducive to the development of dust storms, dust days' emission thresholds, based on number of dust emission events per day / per region and specific to each of the eight main dust emitting regions, were determined. ERA Interim reanalysis data were used to characterise synoptic conditions on the identified dust days. With vegetation cover dictating the ability for surface areas to deflate, Normalised Difference Vegetation Index (NDVI) data was acquired from the Moderate Resolution Imaging Spectrodiometer (MODIS) (MOD13A2) 1km database and correlated with dust emission frequency data in the region of greatest dust activity, the Tigris and Euphrates flood plain in Iraq and Syria.

Wide-field Imaging Survey of Dust Continuum Emissions at lambda = 1.1 mm toward the Chamaeleon and Lupus Regions with AzTEC on ASTE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Momose, Munetake; Hiramatsu, Masaaki; Tsukagoshi, Takashi

2009-08-05

We carried out an imaging survey of dust continuum emissions toward the Chamaeleon and Lupus regions. Observations were made with the 144-element bolometer array camera AzTEC mounted on the 10-meter sub-millimeter telescope ASTE during 2007-2008. The preliminary results of disk search and the cloud structure of Lupus III are presented.

Straightforward fabrication of black nano silica dusting powder for latent fingerprint imaging

NASA Astrophysics Data System (ADS)

Komalasari, Isna; Krismastuti, Fransiska Sri Herwahyu; Elishian, Christine; Handayani, Eka Mardika; Nugraha, Willy Cahya; Ketrin, Rosi

2017-11-01

Imaging of latent fingerprint pattern (aka fingermark) is one of the most important and accurate detection methods in forensic investigation because of the characteristic of individual fingerprint. This detection technique relies on the mechanical adherence of fingerprint powder to the moisture and oily component of the skin left on the surface. The particle size of fingerprint powder is one of the critical parameter to obtain excellent fingerprint image. This study develops a simple, cheap and straightforward method to fabricate Nano size black dusting fingerprint powder based on Nano silica and applies the powder to visualize latent fingerprint. The nanostructured silica was prepared from tetraethoxysilane (TEOS) and then modified with Nano carbon, methylene blue and sodium acetate to color the powder. Finally, as a proof-of-principle, the ability of this black Nano silica dusting powder to image latent fingerprint is successfully demonstrated and the results show that this fingerprint powder provides clearer fingerprint pattern compared to the commercial one highlighting the potential application of the nanostructured silica in forensic science.

Rift Valley fever virus incorporates the 78kDa glycoprotein into virions matured in C6/36 2 mosquito cells

USDA-ARS?s Scientific Manuscript database

Rift Valley fever virus (RVFV), genus Phlebovirus, family Bunyaviridae is a zoonotic arthropod-borne virus able to transition between distant host species, causing potentially severe disease in humans and ruminants. Viral proteins are encoded by three genomic segments, with the medium M segment codi...

Type Theory, Computation and Interactive Theorem Proving

DTIC Science & Technology

2015-09-01

postdoc Cody Roux, to develop new methods of verifying real-valued inequalities automatically. They developed a prototype implementation in Python [8] (an...he has developed new heuristic, geometric methods of verifying real-valued inequalities. A python -based implementation has performed surprisingly...express complex mathematical and computational assertions. In this project, Avigad and Harper developed type-theoretic algorithms and formalisms that

77 FR 43861 - Importer of Controlled Substances; Notice Of Application; Cody Laboratories, Inc.

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-26

... basic class of any controlled substance in schedule I or II are, and will continue to be, required to... importer of the following basic classes of controlled substances: Drug Schedule Opium, Raw (9600) II Concentrate Poppy Straw (9670) II Tapentadol (9780) II The company plans to import narcotic raw materials for...

Submillimeter Imaging of Dust Around Main Sequence Stars

NASA Technical Reports Server (NTRS)

Jewitt, David

1998-01-01

This grant was to image circumstellar dust disks surrounding main-sequence stars. The delivery of the SCUBA detector we had planned to use for this work was delayed repeatedly, leading us to undertake a majority of the observations with the UKT14 submillimeter detector at the JCMT (James Clerk Maxwell Telescope) and optical imagers and a coronagraph at the University of Hawaii 2.2-m telescope. Major findings under this grant include: (1) We discovered 5 asymmetries in the beta Pictoris regenerated dust disk. The discovery of these asymmetries was a surprise, since smearing due to Keplerian shear should eliminate most such features on timescales of a few thousand years. One exception is the "wing tilt" asymmetry, which we interpret as due to the scattering phase function of dust disk particles. From the wing tilt and a model of the phase function, we find a disk plane inclination to the line of sight of < 5 degrees. Other asymmetries (e.g. the butterfly asymmetry) suggest a disk that has been recently disturbed. We searched for possible nearby perturbers but found no clear candidates. Low mass stars (M dwarfs) and brown dwarfs would have fallen beneath the sensitivity threshhold of our survey, however. (2) We calculated a set of disk models to assess the detectability of dust disks around stars as a function of (a) distance, (b) disk, inclination (c) dust optical depth/mass, and (d) imaging resolution. These models guided our observational strategy on Mauna Kea. (3) We performed a coronagraphic survey of approx. 100 main-sequence stars in search of additional examples of circumstellar disks. The best new candidate disk, around the 5 M(sun) star BD+31deg.643, is distinguished by its large extent (few x 10( exp 3) AU). This disk, if real, cannot be rotationally supported. We suggest that the dust particles are ejected from a smaller, unseen disk (Kuiper Belt?) by strong radiation pressure forces due to the high luminosity central star. (4) SCUBA images of circumstellar dust disks were obtained at 850 gm in 1997/8. These images show extended, asymmetric emission, but have a signal-to-noise ratio too low to permit disk mapping to large projected distances. Our images of beta Pic, in particular, are in agreement with those obtained by Holland et al., and appear to confirm the blob-structure reported first by these authors. We have not yet been able to confirm that the structure is intrinsic to the disk, since beta Pic is at -50 degree declination, and suitable observing opportunities from northern latitudes are comparatively rare (even at the +20 degree latitude of JCMT). It is possible, for instance, that the main 850 micro-m blob is merely a galaxy or other high-z source projected onto the beta Pic mid-plane.

Phoenix Magnetic Properties Experiments Using the Surface Stereo Imager and the MECA Microscopy Station

NASA Astrophysics Data System (ADS)

Madsen, M. B.; Drube, L.; Falkenberg, T. V.; Haspang, M. P.; Ellehoj, M.; Leer, K.; Olsen, L. D.; Goetz, W.; Hviid, S. F.; Gunnlaugsson, H. P.; Hecht, M. H.; Parrat, D.; Lemmon, M. T.; Morris, R. V.; Pike, T.; Sykulska, H.; Vijendran, S.; Britt, D.; Staufer, U.; Marshall, J.; Smith, P. H.

2008-12-01

Phoenix carries as part of its scientific payload a series of magnetic properties experiments designed to utilize onboard instruments for the investigation of airborne dust, air-fall samples stirred by the retro-rockets of the lander, and sampled surface and sub-surface material from the northern plains of Mars. One of the aims of these experiments on Phoenix is to investigate any possible differences between airborne dust and soils found on the northern plains from similar samples in the equatorial region of Mars. The magnetic properties experiments are designed to control the pattern of dust attracted to or accumulated on the surfaces to enable interpretation of these patterns in terms of certain magnetic properties of the dust forming the patterns. The Surface Stereo Imager (SSI) provides multi-spectral information about dust accumulated on three iSweep targets on the lander instrument deck. The iSweeps utilize built in permanent magnets and 6 different background colors for the dust compared to only 1 for the MER sweep magnet. Simultaneously these iSweep targets are used as in-situ radiometric calibration targets for the SSI. The visible/near-infrared spectra acquired so far are similar to typical Martian dust and soil spectra. Because of the multiple background colors of the iSweeps the effect of the translucence of thin dust layers can be estimated. High resolution images (4 micrometers/px) acquired by the Optical Microscope (OM) showed subtle differences between different soil samples in particle size distribution, color and morphology. Most samples contain (typically 50 micrometer) large, subrounded particles that are substantially magnetic. The colors of these particles range from red, brown to (almost) black. Based on results from the Mars Exploration Rovers, these dark particles are believed to be enriched in magnetite. Occasionally, also very bright, whitish particles were found on the magnet substrates, likely held by cohesion forces to the magnet surface and/or to other (magnetic) particles.

The fragmentation of dust in the innermost comae of comets: Possible evidence from ground-based images

NASA Technical Reports Server (NTRS)

Combi, Michael R.

1994-01-01

Dust particles when released from the nucleus of a comet are entrained in the expanding gas flow created by the vaporization of ices (mainly water ice). Traditional approaches to dusty-gas dynamics in the inner comae of comets consider there to be an initial distribution of dust particle sizes which do not fragment or evaporate. The standard Finson-Probstein model (and subsequent variations) yields a one-to-one-to-one correspondence between the size of a dust particle, its terminal velocity owing to gas drag, and its radiation pressure acceleration which creates the notable cometary dust tail. The comparison of a newly developed dust coma model shows that the typical elongated shapes of isophotes in the dust comae of comets on the scale of greater than 10(exp 4) km from the nucleus requires that the one-to-one-to-one relationship between particle size, terminal velocity and radiation pressure acceleration cannot in general be correct. There must be a broad range of particles including those having a small velocity but large radiation pressure acceleration in order to explain the elongated shape. A straightforward way to create such a distribution is if particle fragmentation, or some combination of fragmentation with vaporization, routinely occurs within and/or just outside of the dusty-gas dynamic acceleration region (i.e., up to several hundred km). In this way initially large particles, which are accelerated to fairly slow velocities by gas-drag, fragment to form small particles which still move slowly but are subject to a relatively large radiation pressure acceleration. Fragmentation has already been suggested as one possible interpretation for the flattened gradient in the spatial profiles of dust extracted from Giotto images of Comet Halley. Grain vaporization has been suggested as a possible spatially extended source of coma gases. The general elongated isophote shapes seen in ground-based images for many years represents another possible signature of fragmentation.

Monitoring Atmospheric Dust Opacity at High Latitudes on Mars by Imaging Spectroscopy

NASA Astrophysics Data System (ADS)

Doute, S.; Vincendon, M.; Langevin, Y.; Spiga, A.; Bibring, J.; OMEGA Team

2010-12-01

Micrometer sized mineral particles drifting over Mars surface greatly influence both solar and thermal radiative fluxes in the atmosphere, thus its energy balance and its global circulation. Furthermore any kind of remotely sensed data in the optical domain includes their strong, spatially varying, often annoying contributions. Monitoring the particles as well as identifying the sources and the sinks in relation with surface activity is of paramount importance. Since 2004 and 2006 respectively, the imaging spectrometers OMEGA@MEX and CRISM@MRO perform nadir-looking and EPF observations in the VIS and the NIR for the study of the surface and atmosphere alike. We propose an original method to retrieve the optical depth τ dust of the Martian dust over the targeted scenes at a reference wavelength of one micron. Our method works even if the underlying surface is completely made of minerals (low contrast between surface and atmospheric dust) while being observed at a fixed geometry. Nevertheless it provides the maximum of information when applied to spectra acquired over the same area at different emergence angles. The method is based on a parametrization of the radiative coupling between particles and gas that determines, with local altimetry and the meteorological situation, the absorption band depth of gaseous CO2. The coupling depends on (i) the acquisition geometry (ii) the type, abundance and vertical distribution of particles (iii) the surface albedo As. For each spectro-pixel of an image, comparison of band depths estimated on the one hand from the observed spectrum and on the other hand from a calculated transmission spectrum through the atmospheric gases alone, one can build a precious new observable that directly depends on τ dust. Combining the latter with the radiance factor in the continuum, we evaluate after LUT inversion τ dust and As. After validation on test images, we have applied the present method - associated with a complementary approach proposed by [1] - in order to map dust abundance at high southern latitudes from early to late spring of MY 27 and 28. For that purpose we use a time series of OMEGA images for global coverage associated with a limited number of more spatially focused CRISM observations to determine the scale height of dust vertical distribution. As a result, we obtain de-trended and extended maps that are corrected for changes of optical depth due to varying atmospheric height because of topography. They clearly show dust activity within and around the area covered by the CO2 seasonal deposits. Atmospheric mineral particles are clearly depleted above the latter compared to the surroundings, even if occasional incursions of dusty clouds can occur. We note sudden, strong and spatially localized enhancements of dust opacity that can be traced as they migrate before disappearance. [1] Vincendon et al. JGR 2008

Sources, Sinks, and Transatlantic Transport of North African Dust Aerosol: A Multimodel Analysis and Comparison With Remote Sensing Data

NASA Technical Reports Server (NTRS)

Kim, Dongchul; Chin, Mian; Yu, Hongbin; Diehl, Thomas; Tan, Qian; Kahn, Ralph A.; Tsigaridis, Kostas; Bauer, Susanne E.; Takemura, Toshihiko; Pozzoli, Luca;

Using Aerosol Reflectance for Dust Detection

NASA Astrophysics Data System (ADS)

Bahramvash Shams, S.; Mohammadzade, A.

2013-09-01

In this study we propose an approach for dust detection by aerosol reflectance over arid and urban region in clear sky condition. In urban and arid areas surface reflectance in red and infrared spectral is bright and hence shorter wavelength is required for this detections. Main step of our approach can be mentioned as: cloud mask for excluding cloudy pixels from our calculation, calculate Rayleigh path radiance, construct a surface reflectance data base, estimate aerosol reflectance, detect dust aerosol, dust detection and evaluations of dust detection. Spectral with wavelength 0.66, 0.55, 0.47 μm has been used in our dust detection. Estimating surface reflectance is the most challenging step of obtaining aerosol reflectance from top of atmosphere (TOA) reflectance. Hence for surface estimation we had created a surface reflectance database of 0.05 degree latitude by 0.05 degree longitude resolution by using minimum reflectivity technique (MRT). In order to evaluate our dust detection algorithm MODIS aerosol product MOD04 and common dust detection method named Brightness Temperature Difference (BTD) had been used. We had implemented this method to Moderate Resolution Imaging Spectroradiometer (MODIS) image of part of Iran (7 degree latitude and 8 degree longitude) spring 2005 dust phenomenon from April to June. This study uses MODIS LIB calibrated reflectance high spatial resolution (500 m) MOD02Hkm on TERRA spacecraft. Hence our dust detection spatial resolution will be higher spatial resolution than MODIS aerosol product MOD04 which has 10 × 10 km2 and BTD resolution is 1 km due to the band 29 (8.7 μm), 31 (11 μm), and 32 (12 μm) spatial resolutions.

Characterization of synoptic patterns causing dust outbreaks that affect the Arabian Peninsula

NASA Astrophysics Data System (ADS)

Hermida, L.; Merino, A.; Sánchez, J. L.; Fernández-González, S.; García-Ortega, E.; López, L.

2018-01-01

Dust storms pose serious weather hazards in arid and semiarid regions of the earth. Understanding the main synoptic conditions that give rise to dust outbreaks is important for issuing forecasts and warnings to the public in cases of severe storms. The aim of the present study is to determine synoptic patterns that are associated with or even favor dust outbreaks over the Arabian Peninsula. In this respect, red-green-blue dust composite images from the Meteosat Second Generation (MSG) satellite are used to detect dust outbreaks affecting the Arabian Peninsula, with possible influences in southwestern Asia and northeastern Africa, between 2005 and 2013. The Meteosat imagery yielded a sample of 95 dust storm days. Meteorological fields from NCEP/NCAR reanalysis data of wind fields at 10 m and 250 hPa, mean sea level pressure, and geopotential heights at 850 and 500 hPa were obtained for the dust storm days. Using principal component analysis in T-mode and non-hierarchical k-means clustering, we obtained four major atmospheric circulation patterns associated with dust outbreaks during the study days. Cluster 4 had the largest number of days with dust events, which were constrained to summer, and cluster 3 had the fewest. In clusters 1, 2 and 3, the jet stream favored the entry of a low-pressure area or trough that varied in location between the three clusters. Their most northerly location was found in cluster 4, along with an extensive low-pressure area supporting strong winds over the Arabian Peninsula. The spatial distribution of aerosol optical depth for each cluster obtained was characterized using the Moderate Resolution Imaging Spectroradiometer data. Then, using METAR stations, clusters were also characterized in terms of frequency and visibility.

Dust devils on Mars

NASA Technical Reports Server (NTRS)

Thomas, P. G.; Gierasch, P.

1985-01-01

Large columns of dust have been discovered rising above plains on Mars. The storms are probably analogous to terrestrial dust devils, but their size indicates that they are more similar to tornadoes in intensity. They occur at locations where the soil has been strongly warmed by the Sun, and there the surface is smooth and fine grained. These are the same conditions that favor dust devils on Earth. Warm gas from the lowest atmospheric layer converges and rises in a thin column, with intense swirl developing at the edge of the column. In one area a mosaic of Viking images shows 97 vortices in a three day period. This represents a density of vortices of about one in each 900 square kilometers. Thus, these dust devils may be important in moving dust or starting over dust storms.

Summertime Dust Devil

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-464, 26 August 2003

Dust devils are spinning, columnar vortices of air that move across a landscape, picking up dust as they go. They are common occurrences during summer on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired during northern summer, shows a dust devil in the Phlegra region of Mars near 32.0oN, 182.1oW. Sunlight illuminates the scene from the lower left; the dust devil is casting a columnar shadow toward the upper right. Some dust devils on Mars make streaks as they disrupt the fine coating of dust on the surface--but others do not make streaks. This one did not make a streak. The view shown here is 3 km (1.9 mi) wide.

Image computing techniques to extrapolate data for dust tracking in case of an experimental accident simulation in a nuclear fusion plant.

PubMed

Camplani, M; Malizia, A; Gelfusa, M; Barbato, F; Antonelli, L; Poggi, L A; Ciparisse, J F; Salgado, L; Richetta, M; Gaudio, P

2016-01-01

In this paper, a preliminary shadowgraph-based analysis of dust particles re-suspension due to loss of vacuum accident (LOVA) in ITER-like nuclear fusion reactors has been presented. Dust particles are produced through different mechanisms in nuclear fusion devices, one of the main issues is that dust particles are capable of being re-suspended in case of events such as LOVA. Shadowgraph is based on an expanded collimated beam of light emitted by a laser or a lamp that emits light transversely compared to the flow field direction. In the STARDUST facility, the dust moves in the flow, and it causes variations of refractive index that can be detected by using a CCD camera. The STARDUST fast camera setup allows to detect and to track dust particles moving in the vessel and then to obtain information about the velocity field of dust mobilized. In particular, the acquired images are processed such that per each frame the moving dust particles are detected by applying a background subtraction technique based on the mixture of Gaussian algorithm. The obtained foreground masks are eventually filtered with morphological operations. Finally, a multi-object tracking algorithm is used to track the detected particles along the experiment. For each particle, a Kalman filter-based tracker is applied; the particles dynamic is described by taking into account position, velocity, and acceleration as state variable. The results demonstrate that it is possible to obtain dust particles' velocity field during LOVA by automatically processing the data obtained with the shadowgraph approach.

Image computing techniques to extrapolate data for dust tracking in case of an experimental accident simulation in a nuclear fusion plant

NASA Astrophysics Data System (ADS)

Camplani, M.; Malizia, A.; Gelfusa, M.; Barbato, F.; Antonelli, L.; Poggi, L. A.; Ciparisse, J. F.; Salgado, L.; Richetta, M.; Gaudio, P.

2016-01-01

In this paper, a preliminary shadowgraph-based analysis of dust particles re-suspension due to loss of vacuum accident (LOVA) in ITER-like nuclear fusion reactors has been presented. Dust particles are produced through different mechanisms in nuclear fusion devices, one of the main issues is that dust particles are capable of being re-suspended in case of events such as LOVA. Shadowgraph is based on an expanded collimated beam of light emitted by a laser or a lamp that emits light transversely compared to the flow field direction. In the STARDUST facility, the dust moves in the flow, and it causes variations of refractive index that can be detected by using a CCD camera. The STARDUST fast camera setup allows to detect and to track dust particles moving in the vessel and then to obtain information about the velocity field of dust mobilized. In particular, the acquired images are processed such that per each frame the moving dust particles are detected by applying a background subtraction technique based on the mixture of Gaussian algorithm. The obtained foreground masks are eventually filtered with morphological operations. Finally, a multi-object tracking algorithm is used to track the detected particles along the experiment. For each particle, a Kalman filter-based tracker is applied; the particles dynamic is described by taking into account position, velocity, and acceleration as state variable. The results demonstrate that it is possible to obtain dust particles' velocity field during LOVA by automatically processing the data obtained with the shadowgraph approach.

Development of High-Resolution Dynamic Dust Source Function - A Case Study with a Strong Dust Storm in a Regional Model

NASA Technical Reports Server (NTRS)

Kim, Dongchul; Chin, Mian; Kemp, Eric M.; Tao, Zhining; Peters-Lidard, Christa D.; Ginoux, Paul

2017-01-01

A high-resolution dynamic dust source has been developed in the NASA Unified-Weather Research and Forecasting (NU-WRF) model to improve the existing coarse static dust source. In the new dust source map, topographic depression is in 1-km resolution and surface bareness is derived using the Normalized Difference Vegetation Index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS). The new dust source better resolves the complex topographic distribution over the Western United States where its magnitude is higher than the existing, coarser resolution static source. A case study is conducted with an extreme dust storm that occurred in Phoenix, Arizona in 0203 UTC July 6, 2011. The NU-WRF model with the new high-resolution dynamic dust source is able to successfully capture the dust storm, which was not achieved with the old source identification. However the case study also reveals several challenges in reproducing the time evolution of the short-lived, extreme dust storm events.

Development of High-Resolution Dynamic Dust Source Function -A Case Study with a Strong Dust Storm in a Regional Model

PubMed Central

Kim, Dongchul; Chin, Mian; Kemp, Eric M.; Tao, Zhining; Peters-Lidard, Christa D.; Ginoux, Paul

2018-01-01

A high-resolution dynamic dust source has been developed in the NASA Unified-Weather Research and Forecasting (NU-WRF) model to improve the existing coarse static dust source. In the new dust source map, topographic depression is in 1-km resolution and surface bareness is derived using the Normalized Difference Vegetation Index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS). The new dust source better resolves the complex topographic distribution over the Western United States where its magnitude is higher than the existing, coarser resolution static source. A case study is conducted with an extreme dust storm that occurred in Phoenix, Arizona in 02-03 UTC July 6, 2011. The NU-WRF model with the new high-resolution dynamic dust source is able to successfully capture the dust storm, which was not achieved with the old source identification. However the case study also reveals several challenges in reproducing the time evolution of the short-lived, extreme dust storm events. PMID:29632432

Development of High-Resolution Dynamic Dust Source Function -A Case Study with a Strong Dust Storm in a Regional Model.

PubMed

Kim, Dongchul; Chin, Mian; Kemp, Eric M; Tao, Zhining; Peters-Lidard, Christa D; Ginoux, Paul

2017-06-01

A high-resolution dynamic dust source has been developed in the NASA Unified-Weather Research and Forecasting (NU-WRF) model to improve the existing coarse static dust source. In the new dust source map, topographic depression is in 1-km resolution and surface bareness is derived using the Normalized Difference Vegetation Index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS). The new dust source better resolves the complex topographic distribution over the Western United States where its magnitude is higher than the existing, coarser resolution static source. A case study is conducted with an extreme dust storm that occurred in Phoenix, Arizona in 02-03 UTC July 6, 2011. The NU-WRF model with the new high-resolution dynamic dust source is able to successfully capture the dust storm, which was not achieved with the old source identification. However the case study also reveals several challenges in reproducing the time evolution of the short-lived, extreme dust storm events.

The Circumstellar Disk HD 169142: Gas, Dust, and Planets Acting in Concert?

NASA Astrophysics Data System (ADS)

Pohl, A.; Benisty, M.; Pinilla, P.; Ginski, C.; de Boer, J.; Avenhaus, H.; Henning, Th.; Zurlo, A.; Boccaletti, A.; Augereau, J.-C.; Birnstiel, T.; Dominik, C.; Facchini, S.; Fedele, D.; Janson, M.; Keppler, M.; Kral, Q.; Langlois, M.; Ligi, R.; Maire, A.-L.; Ménard, F.; Meyer, M.; Pinte, C.; Quanz, S. P.; Sauvage, J.-F.; Sezestre, É.; Stolker, T.; Szulágyi, J.; van Boekel, R.; van der Plas, G.; Villenave, M.; Baruffolo, A.; Baudoz, P.; Le Mignant, D.; Maurel, D.; Ramos, J.; Weber, L.

2017-11-01

HD 169142 is an excellent target for investigating signs of planet-disk interaction due to previous evidence of gap structures. We perform J-band (˜1.2 μm) polarized intensity imaging of HD 169142 with VLT/SPHERE. We observe polarized scattered light down to 0.″16 (˜19 au) and find an inner gap with a significantly reduced scattered-light flux. We confirm the previously detected double-ring structure peaking at 0.″18 (˜21 au) and 0.″56 (˜66 au) and marginally detect a faint third gap at 0.″70-0.″73 (˜82-85 au). We explore dust evolution models in a disk perturbed by two giant planets, as well as models with a parameterized dust size distribution. The dust evolution model is able to reproduce the ring locations and gap widths in polarized intensity but fails to reproduce their depths. However, it gives a good match with the ALMA dust continuum image at 1.3 mm. Models with a parameterized dust size distribution better reproduce the gap depth in scattered light, suggesting that dust filtration at the outer edges of the gaps is less effective. The pileup of millimeter grains in a dust trap and the continuous distribution of small grains throughout the gap likely require more efficient dust fragmentation and dust diffusion in the dust trap. Alternatively, turbulence or charging effects might lead to a reservoir of small grains at the surface layer that is not affected by the dust growth and fragmentation cycle dominating the dense disk midplane. The exploration of models shows that extracting planet properties such as mass from observed gap profiles is highly degenerate. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 095.C-0273.

Numerical simulation of "An American Haboob"

NASA Astrophysics Data System (ADS)

Vukovic, A.; Vujadinovic, M.; Pejanovic, G.; Andric, J.; Kumjian, M. R.; Djurdjevic, V.; Dacic, M.; Prasad, A. K.; El-Askary, H. M.; Paris, B. C.; Petkovic, S.; Nickovic, S.; Sprigg, W. A.

2013-10-01

A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land-atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High resolution numerical models are required for accurate simulation of the small-scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME-DREAM with 3.5 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the Normalized Difference Vegetation Index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (~ 25 km), the model PM10 surface dust concentration reached ~ 2500 μg m-3, but underestimated the values measured by the PM10stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osorio, Mayra; Anglada, Guillem; Macías, Enrique

We present Very Large Array observations at 7 mm that trace the thermal emission of large dust grains in the HD 169142 protoplanetary disk. Our images show a ring of enhanced emission of radius ∼25-30 AU, whose inner region is devoid of detectable 7 mm emission. We interpret this ring as tracing the rim of an inner cavity or gap, possibly created by a planet or a substellar companion. The ring appears asymmetric, with the western part significantly brighter than the eastern one. This azimuthal asymmetry is reminiscent of the lopsided structures that are expected to be produced as a consequence of trappingmore » of large dust grains. Our observations also reveal an outer annular gap at radii from ∼40 to ∼70 AU. Unlike other sources, the radii of the inner cavity, the ring, and the outer gap observed in the 7 mm images, which trace preferentially the distribution of large (millimeter/centimeter sized) dust grains, coincide with those obtained from a previous near-infrared polarimetric image, which traces scattered light from small (micron-sized) dust grains. We model the broadband spectral energy distribution and the 7 mm images to constrain the disk physical structure. From this modeling we infer the presence of a small (radius ∼0.6 AU) residual disk inside the central cavity, indicating that the HD 169142 disk is a pre-transitional disk. The distribution of dust in three annuli with gaps in between them suggests that the disk in HD 169142 is being disrupted by at least two planets or substellar objects.« less

Back-to-Back Martian Dust Storms

NASA Image and Video Library

2017-03-09

This frame from a movie clip of hundreds of images from NASA's Mars Reconnaissance Orbiter shows a global map of Mars with atmospheric changes from Feb. 18, 2017 through March 6, 2017, a period when two regional-scale dust storms appeared. It combines hundreds of images from the Mars Color Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter. The date for each map in the series is given at upper left. Dust storms appear as pale tan. In the opening frames, one appears left of center, near the top (north) of the map, then grows in size as it moves south, eventually spreading to about half the width of the map after reaching the southern hemisphere. As the dust from that first storm becomes more diffuse in the south, another storm appears near the center of the map in the final frames. In viewing the movie, it helps to understand some of the artifacts produced by the nature of MARCI images when seen in animation. MARCI acquires images in swaths from pole-to-pole during the dayside portion of each orbit. The camera can cover the entire planet in just over 12 orbits, and takes about one day to accumulate this coverage. The individual swaths for each day are assembled into a false-color, map-projected mosaic for the day. Equally spaced blurry areas that run from south-to-north result from the high off-nadir viewing geometry in those parts of each swath, a product of the spacecraft's low orbit. Portions with sharper-looking details are the central part of an image, viewing more directly downward through less atmosphere than the obliquely viewed portions. MARCI has a 180-degree field of view, and Mars fills about 78 percent of that field of view when the camera is pointed down at the planet. However, the Mars Reconnaissance Orbiter often is pointed to one side or the other off its orbital track in order to acquire targeted observations by other imaging systems on the spacecraft. When such rolls exceed about 20 degrees, gaps occur in the mosaic of MARCI swaths. Other dark gaps appear where data are missing. It isn't easy to see the actual dust motion in the atmosphere in these images, owing to the apparent motion of these artifacts. However, by concentrating on specific surface features (craters, prominent ice deposits, etc.) and looking for the tan clouds of dust, it is possible to see where the storms start and how they grow, move and eventually dissipate. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA21484

Measuring Dust Emission from the Mojave Desert (USA) by Daily Remote-Camera Observations and Wind-Erosion Measurements: Bearing on "Unseen" Sources and Global Dust Abundance

NASA Astrophysics Data System (ADS)

Reynolds, R. L.; Urban, F.; Goldstein, H. L.; Fulton, R.

2017-12-01

A large gap in understanding the effects of atmospheric dust at all spatial scales is uncertainty about how much and whence dust is emitted annually. Digital recording of dust emission at high spatial and temporal resolution would, together with periodic flux measurements, support improved estimates of local-scale dust flux where infrastructure could support remote internet enabled cameras. Such recording would also elucidate wind-erosion dynamics when combined with meteorological data. Remote camera recording of dust-emitting settings on and around Soda Lake (Mojave Desert) was conducted every 15 minutes during daylight between 10 Nov. 2010 and 31 Dec. 2016 and images uploaded to a web server. Examination of 135,000 images revealed frequent dust events, termed "dust days" when plumes obscured mountains beyond source areas. Such days averaged 68 (sd=10) per year (2011 through 2016). We examined satellite retrievals (MODIS, GOES) for dust events during six cloudless days of highest and longest duration dust emission but none were observed. From Apr. 2000 through May 2013, aeolian sediments collected at three sites were sampled and weighed. Estimates of the emitted mass of silt- and clay-size fractions were made on the basis of measured horizontal mass flux, particle sizes of sediment in collectors, and roughly determined areas of dust generation. Over this period, nearly 4 Tg yr-1 of dust (as particulate matter <63 micrometers) were emitted across the study area. Much higher rates (about 7 Tg yr-1) were estimated for a subset period from Jan. 2011 through May 2013 following a major Mojave River flood in the basin in late Dec. 2010 that deposited flood sediment across the lake basin. Increased emission was likely related to the availability of fresh, unanchored flood sediment. Within the Mojave and Great Basin deserts of North America, many settings akin to those at Soda Lake similarly emit dust that is rarely detected in satellite retrievals. These findings strongly imply that local and regional dust emissions from western North America are far underestimated and that, by extension to relatively small dust-source areas across all drylands, global dust emissions may also be underestimated.

Multi-Angle View of the Canary Islands

NASA Technical Reports Server (NTRS)

2000-01-01

A multi-angle view of the Canary Islands in a dust storm, 29 February 2000. At left is a true-color image taken by the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite. This image was captured by the MISR camera looking at a 70.5-degree angle to the surface, ahead of the spacecraft. The middle image was taken by the MISR downward-looking (nadir) camera, and the right image is from the aftward 70.5-degree camera. The images are reproduced using the same radiometric scale, so variations in brightness, color, and contrast represent true variations in surface and atmospheric reflectance with angle. Windblown dust from the Sahara Desert is apparent in all three images, and is much brighter in the oblique views. This illustrates how MISR's oblique imaging capability makes the instrument a sensitive detector of dust and other particles in the atmosphere. Data for all channels are presented in a Space Oblique Mercator map projection to facilitate their co-registration. The images are about 400 km (250 miles)wide, with a spatial resolution of about 1.1 kilometers (1,200 yards). North is toward the top. MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

Particle-Image Velocimeter Having Large Depth of Field

NASA Technical Reports Server (NTRS)

Bos, Brent

2009-01-01

An instrument that functions mainly as a particle-image velocimeter provides data on the sizes and velocities of flying opaque particles. The instrument is being developed as a means of characterizing fluxes of wind-borne dust particles in the Martian atmosphere. The instrument could also adapted to terrestrial use in measuring sizes and velocities of opaque particles carried by natural winds and industrial gases. Examples of potential terrestrial applications include monitoring of airborne industrial pollutants and airborne particles in mine shafts. The design of this instrument reflects an observation, made in field research, that airborne dust particles derived from soil and rock are opaque enough to be observable by use of bright field illumination with high contrast for highly accurate measurements of sizes and shapes. The instrument includes a source of collimated light coupled to an afocal beam expander and an imaging array of photodetectors. When dust particles travel through the collimated beam, they cast shadows. The shadows are magnified by the beam expander and relayed to the array of photodetectors. Inasmuch as the images captured by the array are of dust-particle shadows rather of the particles themselves, the depth of field of the instrument can be large: the instrument has a depth of field of about 11 mm, which is larger than the depths of field of prior particle-image velocimeters. The instrument can resolve, and measure the sizes and velocities of, particles having sizes in the approximate range of 1 to 300 m. For slowly moving particles, data from two image frames are used to calculate velocities. For rapidly moving particles, image smear lengths from a single frame are used in conjunction with particle- size measurement data to determine velocities.

Evolution of the physical properties of dust and cometary dust activity from 67P/Churyumov-Gerasimenko measured in situ by Rosetta/COSIMA

NASA Astrophysics Data System (ADS)

Merouane, Sihane; Stenzel, Oliver; Hilchenbach, Martin; Schulz, Rita; Altobelli, Nicolas; Fischer, Henning; Hornung, Klaus; Kissel, Jochen; Langevin, Yves; Mellado, Eva; Rynö, Jouni; Zaprudin, Boris

2017-07-01

The Cometary Secondary Ion Mass Analyzer (COSIMA) collects dust particles in the coma of 67P/Churyumov-Gerasimenko, images them with a resolution of 14 μm × 14 μm, and measures their composition via time-of-flight secondary ion mass spectrometry. The particles are collected on targets exposed to the cometary flux for periods ranging from several hours to a week. Images are acquired with the internal camera, the COSISCOPE, before and after each exposure period. This paper focuses on the evolution of the dust flux and of the size distribution of the particles derived from the COSISCOPE images during the two years of the mission. The dust flux reaches its maximum at perihelion. We suggest that the delay of 20 d between the activity measured by COSIMA and the gas activity measured by the other instruments on Rosetta is caused by the presence of a volatile-poor dust layer on the nucleus that is removed around perihelion, uncovering volatile-rich layers that then become active. The difference in morphology between the northern and southern hemispheres observed by OSIRIS, the south being more sintered, is also recorded in the COSIMA data by a change in the size distribution during the southern summer, as the large porous aggregates disappear from the COSIMA collection. The properties of the particles collected during an outburst in early September 2016 indicate that these particles were ejected by a violent event and might originate from regions of low tensile strength.

The minimum mass of detectable planets in protoplanetary discs and the derivation of planetary masses from high-resolution observations.

PubMed

Rosotti, Giovanni P; Juhasz, Attila; Booth, Richard A; Clarke, Cathie J

2016-07-01

We investigate the minimum planet mass that produces observable signatures in infrared scattered light and submillimetre (submm) continuum images and demonstrate how these images can be used to measure planet masses to within a factor of about 2. To this end, we perform multi-fluid gas and dust simulations of discs containing low-mass planets, generating simulated observations at 1.65, 10 and 850 μm. We show that the minimum planet mass that produces a detectable signature is ∼15 M ⊕ : this value is strongly dependent on disc temperature and changes slightly with wavelength (favouring the submm). We also confirm previous results that there is a minimum planet mass of ∼20 M ⊕ that produces a pressure maximum in the disc: only planets above this threshold mass generate a dust trap that can eventually create a hole in the submm dust. Below this mass, planets produce annular enhancements in dust outwards of the planet and a reduction in the vicinity of the planet. These features are in steady state and can be understood in terms of variations in the dust radial velocity, imposed by the perturbed gas pressure radial profile, analogous to a traffic jam. We also show how planet masses can be derived from structure in scattered light and submm images. We emphasize that simulations with dust need to be run over thousands of planetary orbits so as to allow the gas profile to achieve a steady state and caution against the estimation of planet masses using gas-only simulations.

Wind-Eroded Landscape

NASA Technical Reports Server (NTRS)

2005-01-01

5 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust-mantled, wind-eroded landscape in the Medusae Sulci region of Mars. Wind eroded the bedrock in this region, and then, later, windblown dust covered much of the terrain.

Location near: 5.7oS, 160.2oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

Martian Dust Collected by Phoenix's Arm

NASA Technical Reports Server (NTRS)

2008-01-01

This image from NASA's Phoenix Lander's Optical Microscope shows particles of Martian dust lying on the microscope's silicon substrate. The Robotic Arm sprinkled a sample of the soil from the Snow White trench onto the microscope on July 2, 2008, the 38th Martian day, or sol, of the mission after landing.

Subsequently, the Atomic Force Microscope, or AFM, zoomed in one of the fine particles, creating the first-ever image of a particle of Mars' ubiquitous fine dust, the most highly magnified image ever seen from another world.

The Atomic Force Microscope was developed by a Swiss-led consortium in collaboration with Imperial College London. The AFM is part of Phoenix's Microscopy, Electrochemistry and Conductivity Analyzer instrument.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Methanol extract of grain dust shows complement fixing activity and other characteristics similar to tannic acid.

PubMed Central

Skea, D; Broder, I

1986-01-01

We have found several similarities between tannic acid and grain dust extract prepared with methanol. Both formed a precipitate with IgG, and these interactions were inhibited by albumin. In addition, both preparations fixed complement; this activity was heat stable and was removed by prior adsorption of the preparations with hide powder. Adsorption with polyvinyl polypyrrolidone reduced the complement-fixing activity of tannic acid but not that of the methanol grain dust extract. The similarities between tannic acid and the methanol grain dust extract are consistent with the presence of a tannin or tanninlike material in grain dust. Images FIGURE 1. PMID:3709479

Mapping the circumsolar dust ring near the orbit of Venus

NASA Astrophysics Data System (ADS)

Jones, M. H.; Bewsher, D.; Brown, D. S.

2017-05-01

Synoptic images obtained from the HI-2 instrument on STEREO-A and -B between 2007 and 2014 have been used to further investigate the circumsolar dust ring at the orbit of Venus that was reported by Jones et al. (2013). The analysis is based on high signal-to-noise ratio photometry of the zodiacal light, using data acquired over 10-day intervals, followed by a process of extracting spatial variability on scales up to about 6.5°. The resulting images provide information about the structure of the ring at the location where it is viewed tangentially. We identify 65 usable data sets that comprise about 11% of the available HI-2 data. Analysis of these images show that the orientation of the ring appears to be different to that of the orbit of Venus, with an inclination of 2.1° and longitude of ascending node of 68.5°. We map the variation of ring density parameters in a frame of reference that is co-rotating with Venus and find a pattern suggestive of dust in a 3: 2 orbital resonance. However, the location of the maxima of dust densities is not as expected from theoretical models, and there is some evidence that the dust density distribution in the ring has a pattern speed that differs from the mean motion of Venus.

Devastated Stellar Neighborhood

NASA Technical Reports Server (NTRS)

2008-01-01

This image from NASA's Spitzer Space Telescope shows the nasty effects of living near a group of massive stars: radiation and winds from the massive stars (white spot in center) are blasting planet-making material away from stars like our sun. The planetary material can be seen as comet-like tails behind three stars near the center of the picture. The tails are pointing away from the massive stellar furnaces that are blowing them outward.

The picture is the best example yet of multiple sun-like stars being stripped of their planet-making dust by massive stars.

The sun-like stars are about two to three million years old, an age when planets are thought to be growing out of surrounding disks of dust and gas. Astronomers say the dust being blown from the stars is from their outer disks. This means that any Earth-like planets forming around the sun-like stars would be safe, while outer planets like Uranus might be nothing more than dust in the wind.

This image shows a portion of the W5 star-forming region, located 6,500 light-years away in the constellation Cassiopeia. It is a composite of infrared data from Spitzer's infrared array camera and multiband imaging photometer. Light with a wavelength of 3.5 microns is blue, while light from the dust of 24 microns is orange-red.

An 11-year analysis of satellite retrievals of dust aerosol over the Red Sea and the Persian Gulf

NASA Astrophysics Data System (ADS)

Banks, Jamie; Brindley, Helen; Schepanski, Kerstin; Stenchikov, Georgiy

2017-04-01

As enclosed seas bordering two large desert regions, the Saharan and Arabian deserts, the maritime environments of the Red Sea and the Persian Gulf are heavily influenced by the presence of desert dust aerosol. The inter-annual variability of dust presence over the Red Sea is analysed and presented, with respect to the summer-time latitudinal gradient in dust loading, which is at a maximum in the far south of the Red Sea and at a minimum in the far north. Two satellite aerosol optical depth (AOD) products from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) and the MODerate resolution Imaging Spectroradiometer (MODIS) instruments are used to quantify this loading over the region. Over an eleven-year period from 2005-2015 the July mean SEVIRI AODs at 630 nm vary between 0.48 and 1.45 in the southern half of the Sea, while in the north this varies between 0.22 and 0.66. Inter-retrieval offsets are observed to occur at higher dust loadings, with pronounced positive MODIS-SEVIRI AOD offsets at AODs greater than 1, indicating substantial and systematic differences between the retrievals over the Red Sea at high dust loadings. These differences appear to be influenced in part by the differences in scattering angle range of the satellite measurements, implying that assumptions of particle shape introduce more substantial biases at the highest dust loadings.

The Dirt on Andromeda

NASA Image and Video Library

2010-02-17

This image from NASA Wide-field Infrared Survey Explorer highlights the dust that speckles the Andromeda galaxy spiral arms. The hot dust, which is being heated by newborn stars, traces the spidery arms all the way to the center of the galaxy.

Hypercat - Hypercube of Clumpy AGN Tori

NASA Astrophysics Data System (ADS)

Nikutta, Robert; Lopez-Rodriguez, Enrique; Ichikawa, Kohei; Levenson, Nancy; Packham, Christopher C.

2017-06-01

Dusty tori surrounding the central engines of Active Galactic Nuclei (AGN) are required by the Unification Paradigm, and are supported by many observations, e.g. variable nuclear absorber (sometimes Compton-thick) in X-rays, reverberation mapping in optical/UV, hot dust emission and SED shapes in NIR/MIR, molecular and cool-dust tori observed with ALMA in sub-mm.While models of AGN torus SEDs have been developed and utilized for a long time, the study of the resolved emission morphology (brightness maps) has so far been under-appreciated, presumably because resolved observations of the central parsec in AGN are only possible very recently. Currently, only NIR+MIR interferometry is capable of resolving the nuclear dust emission (but not of producing images, until MATISSE comes online). Furthermore, MIR interferometry has delivered also puzzling results, e.g. that in some resolved sources the light emanates preferentially from polar directions above the "torus" system, and not from the equatorial plane, where most of the dust is located.We are preparing the release of a panchromatic, fully interpolable hypercube of brightness maps and projected dust images for a large number of CLUMPY torus models (Nenkova+2008), that will help facilitate studies of resolved AGN emission and dust morphologies. Together with the cube we will release a comprehensive set of open-source tools (Python) that will enable researches to work efficiently with this large hypercube:* easy sub-cube selection + memory-mapping (mitigating the too-big-for-RAM problem)* multi-dim image interpolation (get an image at any wavelength & model parameter combination)* simulation of observations with telescopes (compute/provide + apply a PSF) and interferometers (get visibilities)* analyze images with respect to the power contained at all scales and orientations (via 2D steerable wavelets), addressing the seemingly puzzling results mentioned aboveA series of papers is in preparation, aiming at solving the puzzles, and at making predictions about the resolvability of all nearby AGN tori with any combination of current and future instruments (e.g. VLTI+MATISSE, TMT+MICHI, GMT, ELT, JWST, ALMA).

Cloud Interactions

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site]

Released 1 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

Image information: VIS instrument. Latitude 68.4, Longitude 258.8 East (101.2 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Imaging-based dust sensors: equipment and methods

NASA Astrophysics Data System (ADS)

Bonifazi, Giuseppe; Greco, Sonia

2004-05-01

Dust detection and control in real time, represent one of the most challenging problem in all those environments where fine and ultrafine airborne particulate solids products are present. The presence of such products can be linked to several factors, often directly related and influenced by the working-production actions performed. Independently from the causes generating dust, airborne contaminants are an occupational problem of increasing interest as they are related to a wide number of diseases. In particular, airborne dusts are well known to be associated with several classical occupational lung diseases, such as the pneumoconiosis, especially at high levels of exposure. Nowadays there is also an increasing interest in other dust related diseases, from the most serious as cancer and asthma, to those related with allergies or irritation and other illnesses, also occurring at lower levels of exposure. Among the different critical factors influencing health risk for airborne dust exposure, mainly four have to be considered, that is: i) nature of the dust resulting from working in terms of presence of specific poisoning material, i.e. free silica, and morphological and morphometrical attributes of particulates constituting airborne dust; ii) size of the particles, iii) duration of exposure time and, finally, iv) airborne dust concentration in the breathing zone where the worker performs his activity. A correct dust detection is not easy, especially if some of the previous mentioned factors, have to be detected and quantified in real time in order to define specific "on-line" control actions aimed to reduce the level of the exposure to dust of the workers, as for example: i) modification of aspirating devices operating condition, change of filtering cleaning sequence, etc. . The more severe are the environmental conditions, in terms of dust presence (in quantity and quality) more difficult is to utilize efficient sampling devices. Detection devices, in fact, tend to become "blind" to dust as dust presence increases, on the other hand severe dust production conditions is exactly the case where control strategies have to be applied to realize safer conditions for the workers. In this paper the possibility to utilize a new logic to perform an "on-line" airborne dust sampling and analysis utilizing imaging is described with particular reference to dusts flowing in a duct after the caption and before their abatement by classical mechanical filtering. The study was particularly addressed to define, design and implement a logic able to extract those parameters affecting airborne dust behavior with respect to its efficient abatement. All dust sampling was performed directly in an industrial plant where tests were carried out in a controlled environment.

Curiosity Observes Whirlwinds Carrying Martian Dust

NASA Image and Video Library

2017-02-27

Dust devils dance in the distance in this frame from a sequence of images taken by the Navigation Camera on NASA's Curiosity Mars rover on Feb. 12, 2017, during the summer afternoon of the rover's 1,607th Martian day, or sol. Within a broader context view, the rectangular area outlined in black was imaged multiple times over a span of several minutes to check for dust devils. Images from the period with most activity are shown in the inset area. The images are in pairs that were taken about 12 seconds apart, with an interval of about 90 seconds between pairs. Timing is accelerated and not fully proportional in this animation. One dust devil appears at the right edge of the inset -- toward the south from the rover -- in the first few frames. Another appears on the left -- toward south-southeast -- later in the sequence. Contrast has been modified to make frame-to-frame changes easier to see. A black frame is added between repeats of the sequence. Portions of Curiosity are visible in the foreground. The cylindrical UHF (ultra-high frequency) antenna on the left is used for sending data to Mars orbiters, which relay the data to Earth. The angled planes to the right of this antenna are fins of the rover's radioisotope thermoelectric generator, which provides the vehicle's power. The post with a knob on top at right is a low-gain, non-directional antenna that can be used for receiving transmissions from Earth, as backup to the main high-gain antenna (not shown here) used for that purpose. On Mars as on Earth, dust devils are whirlwinds that result from sunshine warming the ground, prompting convective rising of air that has gained heat from the ground. Observations of Martian dust devils provide information about wind directions and interaction between the surface and the atmosphere. An animation is available at http://photojournal.jpl.nasa.gov/catalog/PIA21482

NASA Galaxy Mission Celebrates Sixth Anniversary

NASA Image and Video Library

2009-04-28

NASA Galaxy Evolution Explorer Mission celebrates its sixth anniversary studying galaxies beyond our Milky Way through its sensitive ultraviolet telescope, the only such far-ultraviolet detector in space. The mission studies the shape, brightness, size and distance of distant galaxies across 10 billion years of cosmic history, giving scientists a wealth of data to help us better understand the origins of the universe. One such object is pictured here, the galaxy NGC598, more commonly known as M33. This image is a blend of the Galaxy Evolution Explorer's M33 image and another taken by NASA's Spitzer Space Telescope. M33, one of our closest galactic neighbors, is about 2.9 million light-years away in the constellation Triangulum, part of what's known as our Local Group of galaxies. Together, the Galaxy Evolution Explorer and Spitzer can see a broad spectrum of sky. Spitzer, for example, can detect mid-infrared radiation from dust that has absorbed young stars' ultraviolet light. That's something the Galaxy Evolution Explorer cannot see. This combined image shows in amazing detail the beautiful and complicated interlacing of the heated dust and young stars. In some regions of M33, dust gathers where there is very little far-ultraviolet light, suggesting that the young stars are obscured or that stars further away are heating the dust. In some of the outer regions of the galaxy, just the opposite is true: There are plenty of young stars and very little dust. Far-ultraviolet light from young stars glimmers blue, near-ultraviolet light from intermediate age stars glows green, near-infrared light from old stars burns yellow and orange, and dust rich in organic molecules burns red. The small blue flecks outside the spiral disk of M33 are most likely distant background galaxies. This image is a four-band composite that, in addition to the two ultraviolet bands, includes near infrared as yellow/orange and far infrared as red. http://photojournal.jpl.nasa.gov/catalog/PIA11999

Astronomy in Denver: Spatial distributions of dust properties via far-IR broadband map with HerPlaNS

NASA Astrophysics Data System (ADS)

Asano, Kentaro; Ueta, Toshiya; Ladjal, Djazia; Exter, Katrina; Otsuka, Masaaki; HerPlaNS Consortium

2018-06-01

We present the results of our analyses on dust properties in all of Galactic planetary nebulae based on 5-band broadband images in the far-IR taken with the Herschel Space Observatory.By fitting surface brightness distributions of dust thermal emission at 70, 160, 250, 350 and 500 microns with a single-temperature modified black body function, we derive spatially resolved maps of the dust emissivity power-law index (beta) and dust temperature (Td), as well as the column density.We find that circumstellar dust grains in PNe occupy a specific region in the beta-Td space, which is distinct from that occupied by dust grains in the Interstellar Matter (ISM) and star forming regions (SFRs). Unlike those in the ISM and SFRs, dust grains in PNe exhibit little variation in beta while a large spread in Td, suggesting rather homogeneous dust properties.This work is part of the Herschel Planetary Nebula Survey Plus (HerPlaNS+) supported by the NASA Astrophysics Data Analysis Program.

Field measurements of horizontal forward motion velocities of terrestrial dust devils: Towards a proxy for ambient winds on Mars and Earth

NASA Astrophysics Data System (ADS)

Balme, M. R.; Pathare, A.; Metzger, S. M.; Towner, M. C.; Lewis, S. R.; Spiga, A.; Fenton, L. K.; Renno, N. O.; Elliott, H. M.; Saca, F. A.; Michaels, T. I.; Russell, P.; Verdasca, J.

2012-11-01

Dust devils - convective vortices made visible by the dust and debris they entrain - are common in arid environments and have been observed on Earth and Mars. Martian dust devils have been identified both in images taken at the surface and in remote sensing observations from orbiting spacecraft. Observations from landing craft and orbiting instruments have allowed the dust devil translational forward motion (ground velocity) to be calculated, but it is unclear how these velocities relate to the local ambient wind conditions, for (i) only model wind speeds are generally available for Mars, and (ii) on Earth only anecdotal evidence exists that compares dust devil ground velocity with ambient wind velocity. If dust devil ground velocity can be reliably correlated to the ambient wind regime, observations of dust devils could provide a proxy for wind speed and direction measurements on Mars. Hence, dust devil ground velocities could be used to probe the circulation of the martian boundary layer and help constrain climate models or assess the safety of future landing sites. We present results from a field study of terrestrial dust devils performed in the southwest USA in which we measured dust devil horizontal velocity as a function of ambient wind velocity. We acquired stereo images of more than a 100 active dust devils and recorded multiple size and position measurements for each dust devil. We used these data to calculate dust devil translational velocity. The dust devils were within a study area bounded by 10 m high meteorology towers such that dust devil speed and direction could be correlated with the local ambient wind speed and direction measurements. Daily (10:00-16:00 local time) and 2-h averaged dust devil ground speeds correlate well with ambient wind speeds averaged over the same period. Unsurprisingly, individual measurements of dust devil ground speed match instantaneous measurements of ambient wind speed more poorly; a 20-min smoothing window applied to the ambient wind speed data improves the correlation. In general, dust devils travel 10-20% faster than ambient wind speed measured at 10 m height, suggesting that their ground speeds are representative of the boundary layer winds a few tens of meters above ground level. Dust devil ground motion direction closely matches the measured ambient wind direction. The link between ambient winds and dust devil ground velocity demonstrated here suggests that a similar one should apply on Mars. Determining the details of the martian relationship between dust devil ground velocity and ambient wind velocity might require new in situ or modelling studies but, if completed successfully, would provide a quantitative means of measuring wind velocities on Mars that would otherwise be impossible to obtain.

HUBBLE REVEALS THE HEART OF THE WHIRLPOOL GALAXY

NASA Technical Reports Server (NTRS)

2002-01-01

New images from NASA's Hubble Space Telescope are helping researchers view in unprecedented detail the spiral arms and dust clouds of a nearby galaxy, which are the birth sites of massive and luminous stars. The Whirlpool galaxy, M51, has been one of the most photogenic galaxies in amateur and professional astronomy. Easily photographed and viewed by smaller telescopes, this celestial beauty is studied extensively in a range of wavelengths by large ground- and space-based observatories. This Hubble composite image shows visible starlight as well as light from the emission of glowing hydrogen, which is associated with the most luminous young stars in the spiral arms. M51, also known as NGC 5194, is having a close encounter with a nearby companion galaxy, NGC 5195, just off the upper edge of this image. The companion's gravitational pull is triggering star formation in the main galaxy, as seen in brilliant detail by numerous, luminous clusters of young and energetic stars. The bright clusters are highlighted in red by their associated emission from glowing hydrogen gas. This Wide Field Planetary Camera 2 image enables a research group, led by Nick Scoville (Caltech), to clearly define the structure of both the cold dust clouds and the hot hydrogen and link individual clusters to their parent dust clouds. Team members include M. Polletta (U. Geneva); S. Ewald and S. Stolovy (Caltech); R. Thompson and M. Rieke (U. of Arizona). Intricate structure is also seen for the first time in the dust clouds. Along the spiral arms, dust 'spurs' are seen branching out almost perpendicular to the main spiral arms. The regularity and large number of these features suggests to astronomers that previous models of 'two-arm' spiral galaxies may need to be revisited. The new images also reveal a dust disk in the nucleus, which may provide fuel for a nuclear black hole. The team is also studying this galaxy at near-infrared wavelengths with the NICMOS instrument onboard Hubble. At these wavelengths, the dusty clouds are more transparent and the true distribution of stars is more easily seen. In addition, regions of star formation that are obscured in the optical images are newly revealed in the near-infrared images. This image was composed by the Hubble Heritage Team from Hubble archival data of M51 and is superimposed onto ground-based data taken by Travis Rector (NOAO) at the 0.9-meter telescope at the National Science Foundation's Kitt Peak National Observatory (NOAO/AURA) in Tucson, AZ. Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: N. Scoville (Caltech) and T. Rector (NOAO)

Comparison of Morphologies of Apollo 17 Dust Particles with Lunar Simulant, JSC-1

NASA Technical Reports Server (NTRS)

Liu, Yang; Taylor, Lawrence A.; Hill, Eddy; Kihm, Kenneth D.; Day, James D. M.

2005-01-01

Lunar dust (< 20 microns) makes up approx.20 wt.% of the lunar soil. Because of the abrasive and adhering nature of lunar soil, a detailed knowledge of the morphology (size, shape and abundance) of lunar dust is important for dust mitigation on the Moon. This represents a critical step towards the establishment of long-term human presence on the Moon (Taylor et al. 2005). Machinery design for in-situ resource utilization (ISRU) on the Moon also requires detailed information on dust morphology and general physical/chemical characteristics. Here, we report a morphological study of Apollo 17 dust sample 70051 and compare it to lunar soil stimulant, JSC-1. W e have obtained SEM images of dust grains from sample 70051 soil (Fig. 1). The dust grains imaged are composed of fragments of minerals, rocks, agglutinates and glass. Most particles consist largely of agglutinitic impact glass with their typical vesicular textures (fine bubbles). All grains show sub-angular to angular shapes, commonly with sharp edges, common for crushed glass fragments. There are mainly four textures: (1) ropey-textured pieces (typical for agglutinates), (2) angular shards, (3) blocky bits, and (4) Swiss-cheese grains. This last type with its high concentration of submicron bubbles, occurs on all scales. Submicron cracks are also present in most grains. Dust-sized grains of lunar soil simulant, JSC-1, were also studied. JSC-1 is a basaltic tuff with relatively high glass content (approx.50%; McKay et al. 1994). It was initially chosen in the early 90s to approximate the geotechnical properties of the average lunar soil (Klosky et al. 1996). JSC-1 dust grains also show angular blocky and shard textures (Fig. 2), similar to those of lunar dust. However, the JSC-1 grains lack the Swiss-cheese textured particles, as well as submicron cracks and bubbles in most grains.

Revealing the Galactic Center in the Far-Infrared with SOFIA/FORCAST

NASA Astrophysics Data System (ADS)

Lau, Ryan M.; Herter, Terry; Morris, Mark; Li, Zhiyuan; Becklin, Eric; Adams, Joseph; Hankins, Matthew

2015-08-01

We present a summary of far-infrared imaging observations of the inner 40 pc of the Galactic center addressing the dense, dusty torus around Sgr A*, massive star formation, and dust production around massive stars and in the Sgr A East supernova remnant. Observations of warm dust emission were performed using the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST). The Circumnuclear Ring (CNR) surrounding and heated by central cluster in the vicinity of Sgr A* shows no internal active star formation but does exhibit significant density “clumps,” a surprising result because tidal shearing should act quickly to smear out structure. G-0.02-0.07, a complex consisting of three compact HII regions and one ultracompact HII region, is site of the most recent confirmed star formation within ~10 pc of the Galactic center. Our observations reveal the dust morphologies and SEDs of the regions to constrain the composition and gas-to-dust mass ratios of the emitting dust and identify heating sources candidates from archival near-IR images. FORCAST observations Luminous Blue Variables (LBVs) located in and near the Quintuplet Cluster reveal the asymmetric, compressed shell of hot dust surrounding the Pistol Star and provide the first detection of the thermal emission from the symmetric, hot dust envelope surrounding G0.120-0.048. These two LBV’s have nebulae with similar quantities of dust (~0.02 M⊙) but exhibit contrasting appearances due to the external influence of their different environments. Finally, the far-infrared observations indicate the presence of ~0.02 M⊙ of warm (~100 K) dust in the hot interior of the ~10,000 yr-old SgrA East supernova remnant indicating the dust has survived the passage of the reverse shock. The results suggest that supernovae may indeed be the dominant dust production mechanism in the dense environment of early Universe galaxies.

Reuyl Crater Dust Avalanches

NASA Image and Video Library

2002-06-04

The rugged, arcuate rim of the 90 km crater Reuyl dominates this NASA Mars Odyssey image. Reuyl crater is at the southern edge of a region known to be blanketed in thick dust based on its high albedo brightness and low thermal inertia values.

78 FR 32245 - Notice of Receipt of Pesticide Products; Registration Applications To Register New Uses

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-29

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DNA Profiling of Convicted Offender Samples for the Combined DNA Index System

ERIC Educational Resources Information Center

Millard, Julie T

2011-01-01

The cornerstone of forensic chemistry is that a perpetrator inevitably leaves trace evidence at a crime scene. One important type of evidence is DNA, which has been instrumental in both the implication and exoneration of thousands of suspects in a wide range of crimes. The Combined DNA Index System (CODIS), a network of DNA databases, provides…

Teachers, Leaders, and Social Justice: A Critical Reflection on a Complicated Exchange

ERIC Educational Resources Information Center

Miller, Cody

2017-01-01

Cody Miller was asked to present on a panel with a fellow doctoral student and a current principal at a local elementary school for a social justice and diversity in school leadership course. Miller's experience on the panel became an informal type of capstone experience as he found himself having to argue and defend social justice teaching…

DNA Fingerprint Analysis of Three Short Tandem Repeat (STR) Loci for Biochemistry and Forensic Science Laboratory Courses

ERIC Educational Resources Information Center

McNamara-Schroeder, Kathleen; Olonan, Cheryl; Chu, Simon; Montoya, Maria C.; Alviri, Mahta; Ginty, Shannon; Love, John J.

2006-01-01

We have devised and implemented a DNA fingerprinting module for an upper division undergraduate laboratory based on the amplification and analysis of three of the 13 short tandem repeat loci that are required by the Federal Bureau of Investigation Combined DNA Index System (FBI CODIS) data base. Students first collect human epithelial (cheek)…

Optical bandgap of single- and multi-layered amorphous germanium ultra-thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Pei; Zaslavsky, Alexander; Longo, Paolo

2016-01-07

Accurate optical methods are required to determine the energy bandgap of amorphous semiconductors and elucidate the role of quantum confinement in nanometer-scale, ultra-thin absorbing layers. Here, we provide a critical comparison between well-established methods that are generally employed to determine the optical bandgap of thin-film amorphous semiconductors, starting from normal-incidence reflectance and transmittance measurements. First, we demonstrate that a more accurate estimate of the optical bandgap can be achieved by using a multiple-reflection interference model. We show that this model generates more reliable results compared to the widely accepted single-pass absorption method. Second, we compare two most representative methods (Taucmore » and Cody plots) that are extensively used to determine the optical bandgap of thin-film amorphous semiconductors starting from the extracted absorption coefficient. Analysis of the experimental absorption data acquired for ultra-thin amorphous germanium (a-Ge) layers demonstrates that the Cody model is able to provide a less ambiguous energy bandgap value. Finally, we apply our proposed method to experimentally determine the optical bandgap of a-Ge/SiO{sub 2} superlattices with single and multiple a-Ge layers down to 2 nm thickness.« less

The nature of (sub-)micrometre cometary dust particles detected with MIDAS

NASA Astrophysics Data System (ADS)

Mannel, T.; Bentley, M. S.; Torkar, K.; Jeszenszky, H.; Romstedt, J.; Schmied, R.

2015-10-01

The MIDAS Atomic Force Microscope (AFM) onboard Rosetta collects dust particles and produces three-dimensional images with nano- to micrometre resolution. To date, several tens of particles have been detected, allowing determination of their properties at the smallest scale. The key features will be presented, including the particle size, their fragile character, and their morphology. These findings will be compared with the results of other Rosetta dust experiments.

PICTURE-C: A NASA Balloon Mission to Directly Image Exozodiacal Dust Around Nearby Stars

NASA Astrophysics Data System (ADS)

Mendillo, Christopher; Hewawasam, Kuravi; Howe, Glenn A.; Martel, Jason; Finn, Susanna; Cook, Timothy; Chakrabarti, Supriya

2018-01-01

The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) mission will directly image debris disks and exozodiacal dust around nearby stars from a high-altitude balloon using a vector vortex coronagraph (VVC). The mission will consist of two flights, the first in September, 2018 and the second in September, 2019. The second flight will also include a microwave kinetic inductance detector (MKID) to provide spectral imaging. We present a progress report for the mission, which recently completed its critical design review. This will include a description of recent major optical design changes that occurred due to a change in the deformable mirror vendor.

MRO MARCI Weather Report for the week of 3 November 2008 - 9 November 2008

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site]

The MARCI acquires a global view of the red planet and its weather patterns every day. Please click on the image above and play the Quicktime movie to see how the weather on Mars changed during this time.

As in previous weeks, notable dust activity continued on Mars this past week. Early in the week, several smaller dust storms were observed near the edge of the residual North Polar Cap. By mid-week, a series of large dust storms coalesced to cloak the southern mid-latitudes. Dust storm activity was also observed closer to the equator over Solis and east of Hesperia. The latter storm has already affected operations at the MER-A (Spirit) landing site in Gusev Crater. Despite relatively clear skies over the Phoenix landing site this past week, the dwindling incoming solar radiation at the landing site proved insufficient for continued operations. After several months of exciting discoveries, the Phoenix mission has officially ended. On a more positive note, the skies over MER-B (Opportunity) in Meridiani remained relatively clear throughout the week.

Earlier Mars Weather Reports are available at the [figure removed for brevity, see original site] Click on image for larger version of Reference Map

The image(s) and caption seen here are value-added products. MSSS personnel processed the images and wrote the caption information. While the image(s) are in the Public Domain, NASA/JPL-Caltech/MSSS requests that you credit the source of the image(s). Re-use of the caption text without credit is plagiarism. Please give the proper credit for use of the image(s) and/or caption.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. Malin Space Science Systems, San Diego, provided and operates the Context Camera and Mars Color Imager.

THE STRUCTURE OF PRE-TRANSITIONAL PROTOPLANETARY DISKS. II. AZIMUTHAL ASYMMETRIES, DIFFERENT RADIAL DISTRIBUTIONS OF LARGE AND SMALL DUST GRAINS IN PDS 70 {sup ,}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashimoto, J.; Wisniewski, J.; Tsukagoshi, T.

The formation scenario of a gapped disk, i.e., transitional disk, and its asymmetry is still under debate. Proposed scenarios such as disk-planet interaction, photoevaporation, grain growth, anticyclonic vortex, eccentricity, and their combinations would result in different radial distributions of the gas and the small (sub-μm size) and large (millimeter size) dust grains as well as asymmetric structures in a disk. Optical/near-infrared (NIR) imaging observations and (sub-)millimeter interferometry can trace small and large dust grains, respectively; therefore multi-wavelength observations could help elucidate the origin of complicated structures of a disk. Here we report Submillimeter Array observations of the dust continuum atmore » 1.3 mm and {sup 12}CO J = 2 → 1 line emission of the pre-transitional protoplanetary disk around the solar-mass star PDS 70. PDS 70, a weak-lined T Tauri star, exhibits a gap in the scattered light from its disk with a radius of ∼65 AU at NIR wavelengths. However, we found a larger gap in the disk with a radius of ∼80 AU at 1.3 mm. Emission from all three disk components (the gas and the small and large dust grains) in images exhibits a deficit in brightness in the central region of the disk, in particular, the dust disk in small and large dust grains has asymmetric brightness. The contrast ratio of the flux density in the dust continuum between the peak position to the opposite side of the disk reaches 1.4. We suggest the asymmetries and different gap radii of the disk around PDS 70 are potentially formed by several (unseen) accreting planets inducing dust filtration.« less

A mini outburst from the nightside of comet 67P/Churyumov-Gerasimenko observed by the OSIRIS camera on Rosetta

NASA Astrophysics Data System (ADS)

Knollenberg, J.; Lin, Z. Y.; Hviid, S. F.; Oklay, N.; Vincent, J.-B.; Bodewits, D.; Mottola, S.; Pajola, M.; Sierks, H.; Barbieri, C.; Lamy, P.; Rodrigo, R.; Koschny, D.; Rickman, H.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J. L.; Bertini, I.; Cremonese, G.; Davidsson, B.; Da Deppo, V.; Debei, S.; De Cecco, M.; Fornasier, S.; Fulle, M.; Groussin, O.; Gutiérrez, P. J.; Ip, W.-H.; Jorda, L.; Keller, H. U.; Kührt, E.; Kramm, J. R.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Lopez Moreno, J. J.; Marzari, F.; Naletto, G.; Thomas, N.; Güttler, C.; Preusker, F.; Scholten, F.; Tubiana, C.

2016-12-01

Context. On 12 March 2015 the OSIRIS WAC camera onboard the ESA Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko observed a small outburst originating from the Imhotep region at the foot of the big lobe of the comet. These measurements are unique since it was the first time that the initial phase of a transient outburst event could be directly observed. Aims: We investigate the evolution of the dust jet in order to derive clues about the outburst source mechanism and the ejected dust particles, in particular the dust mass, dust-to-gas ratio and the particle size distribution. Methods: Analysis of the images and of the observation geometry using comet shape models in combination with gasdynamic modeling of the transient dust jet were the main tools used in this study. Synthetic images were computed for comparison with the observations. Results: Analysis of the geometry revealed that the source region was not illuminated until 1.5 h after the event implying true nightside activity was observed. The outburst lasted for less than one hour and the average dust production rate during the initial four minutes was of the order of 1 kg/s. During this time the outburst dust production rate was approximately constant, no sign for an initial explosion could be detected. For dust grains between 0.01-1 mm a power law size distribution characterized by an index of about 2.6 provides the best fit to the observed radiance profiles. The dust-to-gas ratio of the outburst jet is in the range 0.6-1.8.

The Structure of Pre-Transitional Protoplanetary Disks. II Azimuthal Asymmetries, Different Radial Distributions of Large and Small Dust Grains in PDS 70

NASA Technical Reports Server (NTRS)

Hashimoto, J.; Tsukagoshi, T.; Brown, J. M.; Dong, R.; Muto, T.; Zhu, Z.; Wisniewski, J.; Ohashi, N.; Kudo, T.; Kusakabe, N.;

Plains Traveler

NASA Technical Reports Server (NTRS)

2006-01-01

10 April 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust devil traveling across a plain west-southwest of Schiaparelli Crater, in far eastern Sinus Meridiani. The dust devil is casting a shadow toward the northeast, just south (below) of an egg-shaped crater.

Location near: 6.4oS, 349.3oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Summer

Eagle Nebula Flaunts its Infrared Feathers

NASA Technical Reports Server (NTRS)

2007-01-01

[figure removed for brevity, see original site] Figure 1 [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 2 Figure 3

This set of images from NASA's Spitzer Space Telescope shows the Eagle nebula in different hues of infrared light. Each view tells a different tale. The left picture shows lots of stars and dusty structures with clarity. Dusty molecules found on Earth called polycyclic aromatic hydrocarbons produce most of the red; gas is green and stars are blue.

The middle view is packed with drama, because it tells astronomers that a star in this region violently erupted, or went supernova, heating surrounding dust (orange). This view also reveals that the hot dust is shell shaped, another indication that a star exploded.

The final picture highlights the contrast between the hot, supernova-heated dust (green) and the cooler dust making up the region's dusty star-forming clouds and towers (red, blue and purple).

The left image is a composite of infrared light with the following wavelengths: 3.6 microns (blue); 4.5 microns (green); 5.8 microns (orange); and 8 microns (red). The right image includes longer infrared wavelengths, and is a composite of light of 4.5 to 8.0 microns (blue); 24 microns (green); and 70 microns (red). The middle image is made up solely of 24-micron light.

Derivation of an observation-based map of North African dust emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evan, Amato T.; Fiedler, Stephanie; Zhao, Chun

Changes in the emission, transport and deposition of aeolian dust have profound effects on regional climate, so that characterizing the lifecycle of dust in observations and improving the representation of dust in global climate models is necessary. A fundamental aspect of characterizing the dust cycle is quantifying surface dust fluxes, yet no spatially explicit estimates of this flux exist for the World’s major source regions. Here we present a novel technique for creating a map of the annual mean emitted dust flux for North Africa based on retrievals of dust storm frequency from the Meteosat Second Generation Spinning Enhanced Visiblemore » and InfraRed Imager (SEVIRI) and the relationship between dust storm frequency and emitted mass flux derived from the output of five models that simulate dust. Our results suggest that 64 (±16)% of all dust emitted from North Africa is from the Bodélé depression, and that 13 (±3)% of the North African dust flux is from a depression lying in the lee of the Aïr and Hoggar Mountains, making this area the second most important region of emission within North Africa.« less

Gusev Dust Devil, sol 532

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows a dust devil seen by NASA's Mars Exploration Rover Spirit during the rover's 532nd martian day, or sol (July 2, 2005). The dust-carrying whirlwind is moving across a plain inside Gusev Crater and viewed from Spirit's vantage point on hills rising from the plain. The clip consists of frames taken by Spirit's navigation camera, processed to enhance contrast for anything in the images that changes from frame to frame. The total elapsed time during the taking of these frames was 8 minutes, 48 seconds.

Spirit began seeing dust devil activity around the beginning of Mars' spring season. Activity increased as spring continued, but fell off again for about two weeks during a dust storm. As the dust storm faded away, dust devil activity came back. In the mid-afternoons as the summer solstice approached, dust devils were a very common occurrence on the floor of Gusev crater. The early-spring dust devils tended to move southwest-to-northeast, across the dust devil streaks in Gusev seen from orbit. Increasingly as the season progresses, the dust devils are seen moving northwest-to-southeast, in the same direction as the streaks. Scientists are watching for the big dust devils that leave those streaks.

Mid-infrared multi-wavelength imaging of Ophiuchus IRS 48 transitional disk†

NASA Astrophysics Data System (ADS)

Honda, Mitsuhiko; Okada, Kazushi; Miyata, Takashi; Mulders, Gijs D.; Swearingen, Jeremy R.; Kamizuka, Takashi; Ohsawa, Ryou; Fujiyoshi, Takuya; Fujiwara, Hideaki; Uchiyama, Mizuho; Yamashita, Takuya; Onaka, Takashi

2018-04-01

Transitional disks around the Herbig Ae/Be stars are fascinating targets in the contexts of disk evolution and planet formation. Oph IRS 48 is one of such Herbig Ae stars, which shows an inner dust cavity and azimuthally lopsided large dust distribution. We present new images of Oph IRS 48 at eight mid-infrared (MIR) wavelengths from 8.59 to 24.6 μm taken with COMICS mounted on the 8.2 m Subaru Telescope. The N-band (7 to 13 μm) images show that the flux distribution is centrally peaked with a slight spatial extent, while the Q-band (17 to 25 μm) images show asymmetric double peaks (east and west). Using 18.8- and 24.6 μm images, we derived the dust temperature at both east and west peaks to be 135 ± 22 K. Thus, the asymmetry may not be attributed to a difference in the temperature. Comparing our results with previous modeling works, we conclude that the inner disk is aligned to the outer disk. A shadow cast by the optically thick inner disk has a great influence on the morphology of MIR thermal emission from the outer disk.

Mid-infrared multi-wavelength imaging of Ophiuchus IRS 48 transitional disk†

NASA Astrophysics Data System (ADS)

Honda, Mitsuhiko; Okada, Kazushi; Miyata, Takashi; Mulders, Gijs D.; Swearingen, Jeremy R.; Kamizuka, Takashi; Ohsawa, Ryou; Fujiyoshi, Takuya; Fujiwara, Hideaki; Uchiyama, Mizuho; Yamashita, Takuya; Onaka, Takashi

2018-06-01

Transitional disks around the Herbig Ae/Be stars are fascinating targets in the contexts of disk evolution and planet formation. Oph IRS 48 is one of such Herbig Ae stars, which shows an inner dust cavity and azimuthally lopsided large dust distribution. We present new images of Oph IRS 48 at eight mid-infrared (MIR) wavelengths from 8.59 to 24.6 μm taken with COMICS mounted on the 8.2 m Subaru Telescope. The N-band (7 to 13 μm) images show that the flux distribution is centrally peaked with a slight spatial extent, while the Q-band (17 to 25 μm) images show asymmetric double peaks (east and west). Using 18.8- and 24.6 μm images, we derived the dust temperature at both east and west peaks to be 135 ± 22 K. Thus, the asymmetry may not be attributed to a difference in the temperature. Comparing our results with previous modeling works, we conclude that the inner disk is aligned to the outer disk. A shadow cast by the optically thick inner disk has a great influence on the morphology of MIR thermal emission from the outer disk.

Herschel View of G49 Filament

NASA Image and Video Library

2015-05-28

New images of huge filamentary structures of gas and dust from ESA's Herschel space observatory reveal how matter is distributed across our Milky Way galaxy. Long and flimsy threads emerge from a twisted mix of material, taking on complex shapes. This image shows a filament called G49, which contains 80,000 suns' worth of mass. This huge but slender structure of gas and dust extends about 280 light-years in length, while its diameter is only about 5 light-years across. In this image, longer-wavelength light has been assigned visible colors. Light with wavelengths of 70 microns is blue; 160-micron light is green; and 350-micron light is red. Cooler gas and dust are seen in red and yellow, with temperatures as low as minus 421 degrees Fahrenheit (minus 252 degrees Celsius). In the densest and coolest clumps, the seeds of new generations of stars are taking shape. A brighter clump of matter is visible at the left tip of the wispy thread. This filament is about 18,000 light-years away. The image is oriented with northeast toward the left of the image and southwest toward the right. http://photojournal.jpl.nasa.gov/catalog/PIA19340

The HOSTS Survey—Exozodiacal Dust Measurements for 30 Stars

NASA Astrophysics Data System (ADS)

Ertel, S.; Defrère, D.; Hinz, P.; Mennesson, B.; Kennedy, G. M.; Danchi, W. C.; Gelino, C.; Hill, J. M.; Hoffmann, W. F.; Rieke, G.; Shannon, A.; Spalding, E.; Stone, J. M.; Vaz, A.; Weinberger, A. J.; Willems, P.; Absil, O.; Arbo, P.; Bailey, V. P.; Beichman, C.; Bryden, G.; Downey, E. C.; Durney, O.; Esposito, S.; Gaspar, A.; Grenz, P.; Haniff, C. A.; Leisenring, J. M.; Marion, L.; McMahon, T. J.; Millan-Gabet, R.; Montoya, M.; Morzinski, K. M.; Pinna, E.; Power, J.; Puglisi, A.; Roberge, A.; Serabyn, E.; Skemer, A. J.; Stapelfeldt, K.; Su, K. Y. L.; Vaitheeswaran, V.; Wyatt, M. C.

2018-05-01

The Hunt for Observable Signatures of Terrestrial Systems survey searches for dust near the habitable zones (HZs) around nearby, bright main-sequence stars. We use nulling interferometry in the N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early-type and Sun-like stars, but decrease from {60}-21+16% for stars with previously detected cold dust to {8}-3+10% for stars without such excess, confirming earlier results at higher sensitivity. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 13 zodis (95% confidence) for a sample of stars without cold dust and of 26 zodis when focusing on Sun-like stars without cold dust. However, our data suggest that a more complex luminosity function may be more appropriate. For stars without detectable Large Binocular Telescope Interferometer (LBTI) excess, our upper limits are almost reduced by a factor of two, demonstrating the strength of LBTI target vetting for future exo-Earth imaging missions. Our statistics are limited so far, and extending the survey is critical to informing the design of future exo-Earth imaging surveys.

Spiral Structure and Differential Dust Size Distribution in the LkH(alpha) 330 Disk

NASA Technical Reports Server (NTRS)

Akiyama, Eiji; Hashimoto, Jun; Liu, Hauyu Baobabu; Li, Jennifer I-hsiu; Bonnefoy, Michael; Dong, Ruobing; Hasegawa, Yasuhiro; Henning, Thomas; Sitko, Michael L.; Janson, Markus;

Limb clouds and dust on Mars from images obtained by the Visual Monitoring Camera (VMC) onboard Mars Express

NASA Astrophysics Data System (ADS)

Sánchez-Lavega, A.; Chen-Chen, H.; Ordoñez-Etxeberria, I.; Hueso, R.; del Río-Gaztelurrutia, T.; Garro, A.; Cardesín-Moinelo, A.; Titov, D.; Wood, S.

2018-01-01

The Visual Monitoring Camera (VMC) onboard the Mars Express (MEx) spacecraft is a simple camera aimed to monitor the release of the Beagle-2 lander on Mars Express and later used for public outreach. Here, we employ VMC as a scientific instrument to study and characterize high altitude aerosols events (dust and condensates) observed at the Martian limb. More than 21,000 images taken between 2007 and 2016 have been examined to detect and characterize elevated layers of dust in the limb, dust storms and clouds. We report a total of 18 events for which we give their main properties (areographic location, maximum altitude, limb projected size, Martian solar longitude and local time of occurrence). The top altitudes of these phenomena ranged from 40 to 85 km and their horizontal extent at the limb ranged from 120 to 2000 km. They mostly occurred at Equatorial and Tropical latitudes (between ∼30°N and 30°S) at morning and afternoon local times in the southern fall and northern winter seasons. None of them are related to the orographic clouds that typically form around volcanoes. Three of these events have been studied in detail using simultaneous images taken by the MARCI instrument onboard Mars Reconnaissance Orbiter (MRO) and studying the properties of the atmosphere using the predictions from the Mars Climate Database (MCD) General Circulation Model. This has allowed us to determine the three-dimensional structure and nature of these events, with one of them being a regional dust storm and the two others water ice clouds. Analyses based on MCD and/or MARCI images for the other cases studied indicate that the rest of the events correspond most probably to water ice clouds.

Possible influences of Asian dust aerosols on cloud properties and radiative forcing observed from MODIS and CERES

NASA Astrophysics Data System (ADS)

Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

2006-03-01

The effects of dust storms on cloud properties and Radiative Forcing (RF) are analyzed over Northwestern China from April 2001 to June 2004 using data collected by the MODerate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. Due to changes in cloud microphysics, the instantaneous net RF is increased from -161.6 W/m2 for dust-free clouds to -118.6 W/m2 for dust-contaminated clouds.

Curiosity Checks Under the Dust on a Martian Rock

NASA Image and Video Library

2017-11-01

On a part of "Vera Rubin Ridge" where rover-team researchers sought to determine whether dust coatings are hiding rocks' hematite content, the Mast Camera (Mastcam) on NASA's Curiosity Mars rover took this image of a rock surface that had been brushed with the rover's Dust Removal Tool. The image is shown in the usual full color of featured Mastcam images: with a color adjustment similar to white balancing for approximating how the rocks and sand would appear under daytime lighting conditions on Earth. Sunlight on Mars is tinged by the dusty atmosphere and this adjustment helps geologists recognize color patterns they are familiar with on Earth. In this case, the purplish tint of the brushed area suggested fine-grained hematite. Bright lines within the rocks are fractures filled with calcium sulfate minerals. The brushed area is about 2.5 inches (6 centimeters) across. The image was taken on Sept. 17, 2017, during the 1,819th Martian day, or sol, of Curiosity's work on Mars. Mastcam also imaged this same scene using three special filters that help to identify hematite, an iron-oxide mineral that can provide information about ancient environmental conditions. A science-filters image identifies hematite in this brushed target even more clearly. https://photojournal.jpl.nasa.gov/catalog/PIA22067

Distance determination method of dust particles using Rosetta OSIRIS NAC and WAC data

NASA Astrophysics Data System (ADS)

Drolshagen, E.; Ott, T.; Koschny, D.; Güttler, C.; Tubiana, C.; Agarwal, J.; Sierks, H.; Barbieri, C.; Lamy, P. I.; Rodrigo, R.; Rickman, H.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Bertini, I.; Cremonese, G.; da Deppo, V.; Davidsson, B.; Debei, S.; de Cecco, M.; Deller, J.; Feller, C.; Fornasier, S.; Fulle, M.; Gicquel, A.; Groussin, O.; Gutiérrez, P. J.; Hofmann, M.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Keller, H. U.; Knollenberg, J.; Kramm, J. R.; Kührt, E.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Lopez Moreno, J. J.; Marzari, F.; Naletto, G.; Oklay, N.; Shi, X.; Thomas, N.; Poppe, B.

2017-09-01

The ESA Rosetta spacecraft has been tracking its target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, in close vicinity for over two years. It hosts the OSIRIS instruments: the Optical, Spectroscopic, and Infrared Remote Imaging System composed of two cameras, see e.g. Keller et al. (2007). In some imaging sequences dedicated to observe dust particles in the comet's coma, the two cameras took images at the same time. The aim of this work is to use these simultaneous double camera observations to calculate the dust particles' distance to the spacecraft. As the two cameras are mounted on the spacecraft with an offset of 70 cm, the distance of particles observed by both cameras can be determined by a shift of the particles' apparent trails on the images. This paper presents first results of the ongoing work, introducing the distance determination method for the OSIRIS instrument and the analysis of an example particle. We note that this method works for particles in the range of about 500-6000 m from the spacecraft.

The Relation Between Lung Dust and Lung Pathology in Pneumoconiosis*

PubMed Central

Nagelschmidt, G.

1960-01-01

Methods of isolation and analysis of dust from pneumoconiotic lungs are reviewed, and the results of lung dust analyses for different forms of pneumoconiosis are presented. A tentative classification separates beryllium, aluminium, abrasive fume, and asbestos, which cause interstitial or disseminated fibrosis from quartz, coal, haematite, talc, kaolin, and other dusts, which cause a nodular or focal fibrosis which may change to forms with massive lesions. The data suggest that in the first, but not in the second, group the dusts are relatively soluble; only in the second group do amounts of dust and severity of fibrosis go in parallel for a given form of pneumoconiosis. In classical silicosis the quartz percentage is higher and the amount of total dust much lower than in coal-miners' pneumoconiosis. Mixed forms of both groups occur, for instance, in diatomite workers. The need for more research, especially in the first group, is pointed out. Images PMID:13727444

A new method for analyzing IRAS data to determine the dust temperature distribution

NASA Technical Reports Server (NTRS)

Xie, Taoling; Goldsmith, Paul F.; Zhou, Weimin

1991-01-01

In attempting to analyze the four-band IRAS images of interstellar dust emission, it is found that an inversion theorem recently developed by Chen (1990) enables distribution of the dust to be determined as a function of temperature and thus the total dust column density, for each line of sight. The method and its application to a hypothetical IRAS data set created by assuming a power-law dust temperature distribution, which is characteristic of the actual IRAS data for the Monoceros R2 cloud, are reported. To use the method, the wavelength dependence of the dust emissivity is assumed and a simple function is fitted to the four intensity-wavelength data points. The method is shown to be very successful at retrieving the dust temperature distribution in this case and is expected to have wide applicability to astronomical problems of this type.

High Energy Studies of Astrophysical Dust

NASA Astrophysics Data System (ADS)

Corrales, Lia Racquel

Astrophysical dust---any condensed matter ranging from tens of atoms to micron sized grains---accounts for about one third of the heavy elements produced in stars and disseminated into space. These tiny pollutants are responsible for producing the mottled appearance in the spray of light we call the "Milky Way." However these seemingly inert particles play a strong role in the physics of the interstellar medium, aiding star and planet formation, and perhaps helping to guide galaxy evolution. Most dust grains are transparent to X-ray light, leaving a signature of atomic absorption, but also scattering the light over small angles. Bright X-ray objects serendipitously situated behind large columns of dust and gas provide a unique opportunity to study the dust along the line of sight. I focus primarily on X-ray scattering through dust, which produces a diffuse halo image around a central point source. Such objects have been observed around X-ray bright Galactic binaries and extragalactic objects that happen to shine through the plane of the Milky Way. I use the Chandra X-ray Observatory, a space-based laboratory operated by NASA, which has imaging resolution ideal for studying X-ray scattering halos. I examine several bright X-ray objects with dust-free sight lines to test their viability as templates and develop a parametric model for the Chandra HETG point spread function (PSF). The PSF describes the instrument's imaging response to a point source, an understanding of which is necessary for properly measuring the surface brightness of X-ray scattering halos. I use an HETG observation of Cygnus X-3, one of the brightest objects available in the Chandra archive, to derive a dust grain size distribution. There exist degenerate solutions for the dust scattering halo, but with the aid of Bayesian analytics I am able to apply prior knowledge about the Cyg X-3 sight line to measure the relative abundance of dust in intervening Milky Way spiral arms. I also demonstrate how information from a single scattering halo can be used in conjunction with X-ray spectroscopy to directly measure the dust-to-gas mass ratio, laying the groundwork for future scattering halo surveys. Distant quasars also produce X-rays that pierce the intergalactic medium. These sources invite the unique opportunity to search for extragalactic dust, whether distributed diffusely throughout intergalactic space, surrounding other galaxies, or occupying reservoirs of cool intergalactic gas. I review X-ray scattering in a cosmological context, examining the range and sensitivity of Chandra to detect the low surface brightness levels of intergalactic scattering. Of particular interest is large "grey" dust, which would cause systematic errors in precision cosmology experiments at a level comparable to the size of the error bars sought. This requires using the more exact Mie scattering treatment, which reduces the scattering cross-section for soft X-rays by a factor of about ten, compared to the Rayleigh-Gans approximation used for interstellar X-ray scattering studies. This allows me to relax the limit on intergalactic dust imposed by previous X-ray imaging of a z=4.3 quasar, QSO 1508+5714, which overestimated the scattering intensity. After implementing the Mie solution with the cosmological integral for scattering halo intensity, I found that intergalactic dust will scatter 1-3% of soft X-ray light. Unfortunately the wings of the Chandra PSF are brighter than the surface brightness expected for these intergalactic scattering halos. The X-ray signatures of intergalactic dust may only be visible if a distant quasar suddenly dimmed by a factor of 1000 or more, leaving behind an X-ray scattering echo, or "ghost" halo.

Early Science with the Large Millimeter Telescope: Detection of Dust Emission in Multiple Images of a Normal Galaxy at z > 4 Lensed by a Frontier Fields Cluster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pope, Alexandra; Battisti, Andrew; Wilson, Grant W.

We directly detect dust emission in an optically detected, multiply imaged galaxy lensed by the Frontier Fields cluster MACSJ0717.5+3745. We detect two images of the same galaxy at 1.1 mm with the AzTEC camera on the Large Millimeter Telescope leaving no ambiguity in the counterpart identification. This galaxy, MACS0717-Az9, is at z > 4 and the strong lensing model ( μ = 7.5) allows us to calculate an intrinsic IR luminosity of 9.7 × 10{sup 10} L {sub ⊙} and an obscured star formation rate of 14.6 ± 4.5 M {sub ⊙} yr{sup −1}. The unobscured star formation rate frommore » the UV is only 4.1 ± 0.3 M {sub ⊙} yr{sup −1}, which means the total star formation rate (18.7 ± 4.5 M {sub ⊙} yr{sup −1}) is dominated (75%–80%) by the obscured component. With an intrinsic stellar mass of only 6.9 × 10{sup 9} M {sub ⊙}, MACS0717-Az9 is one of only a handful of z > 4 galaxies at these lower masses that is detected in dust emission. This galaxy lies close to the estimated star formation sequence at this epoch. However, it does not lie on the dust obscuration relation (IRX- β ) for local starburst galaxies and is instead consistent with the Small Magellanic Cloud attenuation law. This remarkable lower mass galaxy, showing signs of both low metallicity and high dust content, may challenge our picture of dust production in the early universe.« less

ESA scientist discovers a way to shortlist stars that might have planets

NASA Astrophysics Data System (ADS)

2002-02-01

Traces of the disc surrounding our Solar System Credits: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA Traces of the disc surrounding our Solar System Traces of the disc surrounding our Solar System. The blue band curving across this image is created by the dust disc surrounding our Solar System. Viewed from afar this would show up as a bright ring surrounding the Sun. The bright band running across the centre of the image is from dust in our Galaxy. This image, taken by the COBE satellite, is a composite of three far-infrared wavelengths (60, 100, and 240 microns). (Photo: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA) Disc surrounding the Sun Credits: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA Viewed from afar our Solar System would have a bright disc surrounding the Sun Viewed from afar our Solar System would have a bright dust disc surrounding the Sun similar to the disc surrounding this star. This image, taken with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), shows a dust ring around a star called HR 4796A. The image was taken on March 15, 1998. (Photo: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA) Ulysses in flight configuration hi-res Size hi-res: 117 Kb Credits: ESA/Dave Hardy Ulysses at Jupiter encounter Ulysses in flight configuration passing by Jupiter. Remarkably, their discovery gives astronomers a way to determine which other stars in the Galaxy are most likely to harbour planets and allows mission planners to draw up a 'short-list' of stars to be observed by ESA's future planet-search missions, Eddington and Darwin. The discovery of the Solar System's dust ring strengthens the idea that such features around mature stars are signposts to planetary systems. The reason for this is that planetary systems are thought to condense from a cloud of gas and dust. Planets form near the central star, where the material is densest. However, at great distances from the star, the gas and dust is sparse and can coalesce only into a vast band of small, icy bodies. In our Solar System, they form the so-called Edgeworth-Kuiper belt that extends out beyond the orbit of Neptune. Any remaining dust is lost to deep space. Ordinarily, dust is either incorporated into larger celestial bodies or ejected from the Solar System. For it still to be present today, means that something is replenishing it. "In order to sustain such a ring, 50 tonnes of dust have to be generated every second," says Landgraf. He and his colleagues believe that collisions between the icy remnants of the Edgeworth-Kuiper belt create the Solar System's dust ring. If the same is going on in other planetary systems, then those stars will also have dusty rings around them. "If you have a dust disc around a star that's not particularly young, then it's extremely interesting because the dust has to come from somewhere. The only explanation is that the star has planets, comets, asteroids or other bodies that collide and generate the dust," says Malcolm Fridlund, ESA's study scientist for Darwin, the mission under development to search for life-supporting planets around other stars. To trace the collisions in the Edgeworth-Kuiper Belt, Landgraf and colleagues had to do some celestial detective work. They began by sifting through data from the 1970s and early 1980s, when NASA space probes Pioneer 10 and 11 first found dust particles of unknown origin beyond Saturn's orbit. The hypothesis of dust coming from comets was discarded: in fact near the Earth, comets give off dust; beyond Saturn, however, they freeze and shed little material. So, no one knew whether the Pioneer dust grains were coming from inside the Solar System - from a source other than comets - or beyond it from the interstellar space. Now, using data from ESA's Ulysses spacecraft, which has been orbiting the poles of the Sun for more than 10 years, Landgraf and colleagues have been able to rule out an origin beyond the Solar System. The Ulysses data shows that dust grains of interstellar origin are considerably smaller than interplanetary dust grains, which originate in the Solar System. The interstellar grains detected by Ulysses are typically ten to a hundred times smaller than the smallest grain that could be detected by Pioneer. Thus, the Pioneer grains have to be made somewhere within our Solar System. So, by a process of elimination and computer simulations, the scientists came to the conclusion that the only possible source of the dust is the collisions between the small, icy objects in the Edgeworth-Kuiper belt. Since these are the remnants of planet formation, the team believe that planetary systems around other stars will also produce constantly replenishing dust rings. From the number of dust particles detected by the Pioneers, Landgraf and colleagues were able to calculate the density of dust in the ring. "There's only one dust particle every 50 cubic kilometres but it's enough for a bright dust ring like those we see around other stars," says Landgraf. Indeed, a number of such features have been observed shining brightly at infrared wavelengths around stars such as Vega and Epsilon Eridani. Future missions, such as ESA's Herschel mission will search for many more and take detailed pictures of them. As these images become available, astronomers will be able to predict the sizes and orbits of giant planets within the alien solar system. "If we see a similar dust ring around a main sequence star (a mature star, like the Sun), we'll know it must have asteroids or comets. If we see gaps in the dust ring, it will probably have planets which are sweeping away the dust as they orbit," says Landgraf. The result slots into place another piece of the puzzle for those scientists working on ESA's missions that will search for extrasolar planets, as it will allow them to draw up a well motivated list of target stars based upon whether they are surrounded by dust rings. "This finding has exciting implications for both missions," confirms Fridlund. The full details of Landgraf's results will be published in a future issue of The Astrophysical Journal.

The dust mass in Cassiopeia A

NASA Astrophysics Data System (ADS)

De Looze, Ilse; Barlow, Mike; Marcowith, Alexandre; Tatischef, Vincent

2016-06-01

Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1 Msun) and potentially responsible for most of the dust production in the early Universe. Observational evidence for this dust production efficiency has remained limited. Herschel observations from 70-500 microns of the 335-year old Cassiopeia A have indicated the presence of ˜0.1 Msun of cool (T˜35 K) dust interior to the reverse shock (Barlow et al. 2010), while Dunne et al. (2009) have claimed a detection of ˜1 Msun of cold (˜20 K) dust, based on SCUBA 850-micron polarimetric data. At sub-millimeter wavelengths, the supernova dust emission is heavily contaminated by interstellar dust emission and by the synchrotron radiation from the SNR. We present the first spatially resolved analysis of the infrared and submillimeter emission of Cas, A at better than 1 parsec resolution, based on our Herschel PACS and SPIRE 70-500um images. We used our PACS IFU and SPIRE FTS spectra to remove the contaminating emission from bright lines (e.g. [OIII]88, [CII]158). We updated the spectral index of the synchrotron emission based on recent Planck data, and extrapolated this synchrotron spectrum from a 3.7 mm VLA image to infrared/submillimeter wavelengths. We modeled the interstellar dust emission using a Galactic dust emission template from Jones et al. (2013), while the ISM dust mass is scaled to reproduce the continuum emission in the SPIRE FTS spectra at wavelengths > 650 micron (after subtraction of synchrotron emission). The UV radiation field that illuminates the ISM dust was constrained through PDR modelling of the [CI] 1-0, 2-1 and CO 4-3 lines observed in the SPIRE FTS spectra, and was found to range between 0.3 G0 and 1.0 G0 in units of the Draine IS radiation field. Within the uncertainties of the radiation field that illuminates the ISM material and the observational errors, we detect a dust mass of up to 0.8 Msun in Cas, A, with an average temperature of 30 K, in the region interior to the reverse shock. Our SN dust mass map has a rather smooth appearance, which suggests that dust formed uniformly throughout the ejecta. A Cas A dust mass of up to 0.8 Msun is in the same range as the ˜0.7 Msun of dust found in SN 1987A (Matsuura et al. 2015) and the ˜0.2 Msun of dust found in the Crab Nebula (Gomez et al. 2012; Owen & Barlow 2015). With these dust masses core-collapse supernovae can potentially account for the very large large masses of dust that have been observed in some high redshift galaxies.

HERSCHEL OBSERVATIONS OF GAS AND DUST IN THE UNUSUAL 49 Ceti DEBRIS DISK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberge, A.; Kamp, I.; Montesinos, B.

2013-07-01

We present far-IR/sub-mm imaging and spectroscopy of 49 Ceti, an unusual circumstellar disk around a nearby young A1V star. The system is famous for showing the dust properties of a debris disk, but the gas properties of a low-mass protoplanetary disk. The data were acquired with the Herschel Space Observatory PACS and SPIRE instruments, largely as part of the ''Gas in Protoplanetary Systems'' (GASPS) Open Time Key Programme. Disk dust emission is detected in images at 70, 160, 250, 350, and 500 {mu}m; 49 Cet is significantly extended in the 70 {mu}m image, spatially resolving the outer dust disk formore » the first time. Spectra covering small wavelength ranges centered on eight atomic and molecular emission lines were obtained, including [O I] 63 {mu}m and [C II] 158 {mu}m. The C II line was detected at the 5{sigma} level-the first detection of atomic emission from the disk. No other emission lines were seen, despite the fact that the O I line is the brightest one observed in Herschel protoplanetary disk spectra. We present an estimate of the amount of circumstellar atomic gas implied by the C II emission. The new far-IR/sub-mm data fills in a large gap in the previous spectral energy distribution (SED) of 49 Cet. A simple model of the new SED confirms the two-component structure of the disk: warm inner dust and cold outer dust that produces most of the observed excess. Finally, we discuss preliminary thermochemical modeling of the 49 Cet gas/dust disk and our attempts to match several observational results simultaneously. Although we are not yet successful in doing so, our investigations shed light on the evolutionary status of the 49 Cet gas, which might not be primordial gas but rather secondary gas coming from comets.« less

Herschel Observations of Gas and Dust in the Unusual 49 Ceti Debris Disk

NASA Technical Reports Server (NTRS)

Roberge, A.; Kamp, I.; Montesinos, B.; Dent, W. R. F.; Meeus, G.; Donaldson, J. K.; Olofsson, J.; Moor, A.; Augereau, J.-C.; Howard, C.;

Herschel Observations of Gas and Dust in the Unusual 49 Ceti Debris Disk

NASA Astrophysics Data System (ADS)

Roberge, A.; Kamp, I.; Montesinos, B.; Dent, W. R. F.; Meeus, G.; Donaldson, J. K.; Olofsson, J.; Moór, A.; Augereau, J.-C.; Howard, C.; Eiroa, C.; Thi, W.-F.; Ardila, D. R.; Sandell, G.; Woitke, P.

2013-07-01

We present far-IR/sub-mm imaging and spectroscopy of 49 Ceti, an unusual circumstellar disk around a nearby young A1V star. The system is famous for showing the dust properties of a debris disk, but the gas properties of a low-mass protoplanetary disk. The data were acquired with the Herschel Space Observatory PACS and SPIRE instruments, largely as part of the "Gas in Protoplanetary Systems" (GASPS) Open Time Key Programme. Disk dust emission is detected in images at 70, 160, 250, 350, and 500 μm 49 Cet is significantly extended in the 70 μm image, spatially resolving the outer dust disk for the first time. Spectra covering small wavelength ranges centered on eight atomic and molecular emission lines were obtained, including [O I] 63 μm and [C II] 158 μm. The C II line was detected at the 5σ level—the first detection of atomic emission from the disk. No other emission lines were seen, despite the fact that the O I line is the brightest one observed in Herschel protoplanetary disk spectra. We present an estimate of the amount of circumstellar atomic gas implied by the C II emission. The new far-IR/sub-mm data fills in a large gap in the previous spectral energy distribution (SED) of 49 Cet. A simple model of the new SED confirms the two-component structure of the disk: warm inner dust and cold outer dust that produces most of the observed excess. Finally, we discuss preliminary thermochemical modeling of the 49 Cet gas/dust disk and our attempts to match several observational results simultaneously. Although we are not yet successful in doing so, our investigations shed light on the evolutionary status of the 49 Cet gas, which might not be primordial gas but rather secondary gas coming from comets.

Sol 568 Dust Devil in Gusev, Unenhanced

NASA Technical Reports Server (NTRS)

2005-01-01

This movie clip shows several dust devils moving from right to left across a plain inside Mars' Gusev Crater, as seen from the vantage point of NASA's Mars Exploration Rover Spirit in hills rising from the plain. The clip consists of frames taken by Spirit's navigation camera during the rover's 543rd martian day, or sol (July 13, 2005). Unlike some other movie clips of dust devils seen by Spirit, the images in this clip have not been processed to enhance contrast of the dust devils. The total time elapsed during the taking of these frames was 12 minutes, 17 seconds.

Spirit began seeing dust devil activity around the beginning of Mars' spring season. Activity increased as spring continued, but fell off again for about two weeks during a dust storm. As the dust storm faded away, dust devil activity came back. In the mid-afternoons as the summer solstice approached, dust devils were a very common occurrence on the floor of Gusev crater. The early-spring dust devils tended to move southwest-to-northeast, across the dust devil streaks in Gusev seen from orbit. Increasingly as the season progresses, the dust devils are seen moving northwest-to-southeast, in the same direction as the streaks. Scientists are watching for the big dust devils that leave those streaks.

Athena Microscopic Imager investigation

NASA Astrophysics Data System (ADS)

Herkenhoff, K. E.; Squyres, S. W.; Bell, J. F.; Maki, J. N.; Arneson, H. M.; Bertelsen, P.; Brown, D. I.; Collins, S. A.; Dingizian, A.; Elliott, S. T.; Goetz, W.; Hagerott, E. C.; Hayes, A. G.; Johnson, M. J.; Kirk, R. L.; McLennan, S.; Morris, R. V.; Scherr, L. M.; Schwochert, M. A.; Shiraishi, L. R.; Smith, G. H.; Soderblom, L. A.; Sohl-Dickstein, J. N.; Wadsworth, M. V.

2003-11-01

The Athena science payload on the Mars Exploration Rovers (MER) includes the Microscopic Imager (MI). The MI is a fixed-focus camera mounted on the end of an extendable instrument arm, the Instrument Deployment Device (IDD). The MI was designed to acquire images at a spatial resolution of 30 microns/pixel over a broad spectral range (400-700 nm). The MI uses the same electronics design as the other MER cameras but has optics that yield a field of view of 31 × 31 mm across a 1024 × 1024 pixel CCD image. The MI acquires images using only solar or skylight illumination of the target surface. A contact sensor is used to place the MI slightly closer to the target surface than its best focus distance (about 66 mm), allowing concave surfaces to be imaged in good focus. Coarse focusing (~2 mm precision) is achieved by moving the IDD away from a rock target after the contact sensor has been activated. The MI optics are protected from the Martian environment by a retractable dust cover. The dust cover includes a Kapton window that is tinted orange to restrict the spectral bandpass to 500-700 nm, allowing color information to be obtained by taking images with the dust cover open and closed. MI data will be used to place other MER instrument data in context and to aid in petrologic and geologic interpretations of rocks and soils on Mars.

Long range transport of fine grained sediments on Mars: Atmospheric dust loading, as inferred from Viking Lander imaging data

NASA Technical Reports Server (NTRS)

Pollack, J. B.; Colburn, D. S.

1984-01-01

During the first Viking year, two global dust storms occurred and they contributed about 90% of the dust suspended in the Martian atmosphere on a global average, over the course of this year. The remainder was due to the cumulative effect of local dust storms. When globally distributed, the amount of suspended dust introduced into the atmosphere this Martian year was about 5x10(-3) g/sq cm. This mass loading was derived from the incremental optical depths measured over this year and estimates of the mean size of the dust particles (2.5 microns). During the second Martian year, global dust storms were far more muted than during the first year. No near perihelion dust storm occurred, and a somewhat weaker dust storm may have occurred near the start of the spring season in the Southern Hemisphere, at about the same time that the first global dust storm of the first year occurred. Thus, the dust loading derived for the first Martian year may be somewhat higher than the average over many Martian years, a conclusion that appears to be supported by preliminary studies of Martian years beyond the second Viking year on Mars.

Hubble Space Telescope Imaging of the Circumnuclear Environments of the CfA Seyfert Galaxies: Nuclear Spirals and Fueling

NASA Technical Reports Server (NTRS)

Pogge, Richard W.; Martini, Paul

2002-01-01

We present archival Hubble Space Telescope (HST) images of the nuclear regions of 43 of the 46 Seyfert galaxies found in the volume limited,spectroscopically complete CfA Redshift Survey sample. Using an improved method of image contrast enhancement, we created detailed high-quality " structure maps " that allow us to study the distributions of dust, star clusters, and emission-line gas in the circumnuclear regions (100-1000 pc scales) and in the associated host galaxy. Essentially all of these Seyfert galaxies have circumnuclear dust structures with morphologies ranging from grand-design two-armed spirals to chaotic dusty disks. In most Seyfert galaxies there is a clear physical connection between the nuclear dust spirals on hundreds of parsec scales and large-scale bars and spiral arms in the host galaxies proper. These connections are particularly striking in the interacting and barred galaxies. Such structures are predicted by numerical simulations of gas flows in barred and interacting galaxies and may be related to the fueling of active galactic nuclei by matter inflow from the host galaxy disks. We see no significant differences in the circumnuclear dust morphologies of Seyfert 1s and 2s, and very few Seyfert 2 nuclei are obscured by large-scale dust structures in the host galaxies. If Sevfert 2s are obscured Sevfert Is, then the obscuration must occur on smaller scales than those probed by HST.

Nine martian years of dust optical depth observations: A reference dataset

NASA Astrophysics Data System (ADS)

Montabone, Luca; Forget, Francois; Kleinboehl, Armin; Kass, David; Wilson, R. John; Millour, Ehouarn; Smith, Michael; Lewis, Stephen; Cantor, Bruce; Lemmon, Mark; Wolff, Michael

2016-07-01

We present a multi-annual reference dataset of the horizontal distribution of airborne dust from martian year 24 to 32 using observations of the martian atmosphere from April 1999 to June 2015 made by the Thermal Emission Spectrometer (TES) aboard Mars Global Surveyor, the Thermal Emission Imaging System (THEMIS) aboard Mars Odyssey, and the Mars Climate Sounder (MCS) aboard Mars Reconnaissance Orbiter (MRO). Our methodology to build the dataset works by gridding the available retrievals of column dust optical depth (CDOD) from TES and THEMIS nadir observations, as well as the estimates of this quantity from MCS limb observations. The resulting (irregularly) gridded maps (one per sol) were validated with independent observations of CDOD by PanCam cameras and Mini-TES spectrometers aboard the Mars Exploration Rovers "Spirit" and "Opportunity", by the Surface Stereo Imager aboard the Phoenix lander, and by the Compact Reconnaissance Imaging Spectrometer for Mars aboard MRO. Finally, regular maps of CDOD are produced by spatially interpolating the irregularly gridded maps using a kriging method. These latter maps are used as dust scenarios in the Mars Climate Database (MCD) version 5, and are useful in many modelling applications. The two datasets (daily irregularly gridded maps and regularly kriged maps) for the nine available martian years are publicly available as NetCDF files and can be downloaded from the MCD website at the URL: http://www-mars.lmd.jussieu.fr/mars/dust_climatology/index.html

JWST DD ERS Team Update: Decoding Smoke Signals from WR140 using NIRISS+AMI and MIRI/MRS

NASA Astrophysics Data System (ADS)

Lau, Ryan M.; Hankins, Matt; WR DustERS Team

2018-06-01

Dust is a key component of the interstellar medium and plays and important role in the formation of stars and planets. However, the dominant channels of dust production throughout cosmic time are uncertain. With its unprecedented sensitivity and spatial resolution in the mid-IR, the James Webb Space Telescope (JWST) is the ideal platform to address this issue by investigating the dust abundance, composition, and production rates of various dusty sources. In particular, colliding-wind Wolf-Rayet (WR) binaries are known to be efficient dust producers in the local Universe and likely existed in the earliest galaxies. In our Early Release Science (ERS) program, we will use JWST to observe the archetypal colliding-wind binary, WR 140, to study its dust composition, abundance, and formation mechanisms. We will utilize two key JWST observing modes with the medium-resolution spectrometer (MRS) on the Mid-Infrared Instrument (MIRI) and the Aperture Masking Interferometry (AMI) mode with the Near Infrared Imager and Slitless Spectrograph (NIRISS).Our planned observations will establish a benchmark for key observing modes for imaging bright sources with faint extended emission at high spatial resolutions. This will be valuable in various astrophysical contexts including mass-loss from evolved stars, dusty tori around active galactic nuclei, and protoplanetary disks. We are committed to delivering science-enabling products for the JWST community that include high-level pipeline tools to mitigate bright source artifacts and image reconstruction tools compatible with NIRISS+AMI data.

Subjective Mapping of Dust-Emission Sources by Using MODIS Imagery

DTIC Science & Technology

2017-05-01

within the inset of Panel A. Panel A is a True Color image that depicts white clouds against a brown landscape; a bird’s eye representation of Earth...shows the location of the Hamun dry lakes, which are an important dust source in the region. The enlarged image box in the top right depicts the...Bacon and McDonald 2016). For example, dry lakebeds filled with unconsolidated ERDC/CRREL TR-17-8 4 fine-grained sediments are commonly

Multiwavelength studies of the gas and dust disc of IRAS 04158+2805

NASA Astrophysics Data System (ADS)

Glauser, A. M.; Ménard, F.; Pinte, C.; Duchêne, G.; Güdel, M.; Monin, J.-L.; Padgett, D. L.

2008-07-01

We present a study of the circumstellar environment of IRAS 04158+2805 based on multi-wavelength observations and models. Images in the optical and near-infrared, a polarisation map in the optical, and mid-infrared spectra were obtained with VLT-FORS1, CFHT-IR, and Spitzer-IRS. Additionally we used an X-ray spectrum observed with Chandra. We interpret the observations in terms of a central star surrounded by an axisymmetric circumstellar disc, but without an envelope, to test the validity of this simple geometry. We estimate the structural properties of the disc and its gas and dust content. We modelled the dust disc with a 3D continuum radiative transfer code, MCFOST, based on a Monte-Carlo method that provides synthetic scattered light images and polarisation maps, as well as spectral energy distributions. We find that the disc images and spectral energy distribution narrowly constrain many of the disc model parameters, such as a total dust mass of 1.0-1.75×10-4 M_⊙ and an inclination of 62°-63°. The maximum grain size required to fit all available data is of the order of 1.6-2.8 μm although the upper end of this range is loosely constrained. The observed optical polarisation map is reproduced well by the same disc model, suggesting that the geometry we find is adequate and the optical properties are representative of the visible dust content. We compare the inferred dust column density to the gas column density derived from the X-ray spectrum and find a gas-to-dust ratio along the line of sight that is consistent with the ISM value. To our knowledge, this measurement is the first to directly compare dust and gas column densities in a protoplanetary disc. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Based also on data collected at ESO/VLT during observation program 68-C.0171.

The peculiar asymmetry of NGC 949

NASA Image and Video Library

2015-05-04

This image provides the clearest ever view of galaxy NGC 949, which lies over 30 million light-years away in the constellation of Triangulum. The galaxy has an unusual shape, made more obscure due to its inclination. From our point of view, it is difficult to discern exactly what type of galaxy NGC 949 is, but it is certainly a disc galaxy of some kind, most likely a spiral. NGC 949 was first discovered by Sir William Herschel on 21 September 1786, using an 18.7-inch reflecting telescope. The galaxy was one of about 3000 objects Herschel catalogued as "nebulae" during an intense and systematic deep sky survey, the results of which eventually formed the bulk of the New General Catalogue (NGC). Taken with Hubble’s Advanced Camera for Surveys (ACS), this new image shows extraordinary detail. This detail allows us to see a strange asymmetric alignment in the dark lanes of dust that snake across the galaxy. The top-right half of the galaxy appears considerably more marbled with dust in this image; a curious observation explained by stars tending to favour locations towards the centre of a galaxy, and dust preferring almost invariably to reside along the galactic plane. When a galaxy is inclined as NGC 949 is, some regions — in this case the top-right — are tipped towards us and the light from the stars we see in these regions has had to travel through more dust. This causes the light to appear redder — the result of the same process that gives the sun’s light a red hue at dusk — or else disappear entirely, making the dust appear more prominent on that side of the galaxy. In the part tipped away from us, the light from the stars has had to pass through much less dust to reach us, so it appears brighter, and the dust is much less prominent. Were it possible to view NGC 949 from the opposite side, the apparent alignment of the dust would be reversed. The scientific advantages of this effect were recently displayed in suitably stunning style in the M31 PHAT mosa

The HERschel Inventory of the Agents of Galaxy Evolution in the Magellanic Clouds, a HERschel Open Time Key Program

NASA Technical Reports Server (NTRS)

Meixner, Margaret; Panuzzo, P.; Roman-Duval, J.; Engelbracht, C.; Babler, B.; Seale, J.; Hony, S.; Montiel, E.; Sauvage, M.; Gordon, K.;

Longwave Radiative Forcing of Saharan Dust Aerosols Estimated from MODIS, MISR and CERES Observations on Terra

NASA Technical Reports Server (NTRS)

Zhang, Jiang-Long; Christopher, Sundar A.

2003-01-01

Using observations from the Multi-angle Imaging Spectroradiometer (MISR), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Clouds and the Earth's Radiant Energy System (CERES) instruments onboard the Terra satellite; we present a new technique for studying longwave (LW) radiative forcing of dust aerosols over the Saharan desert for cloud-free conditions. The monthly-mean LW forcing for September 2000 is 7 W/sq m and the LW forcing efficiency' (LW(sub eff)) is 15 W/sq m. Using radiative transfer calculations, we also show that the vertical distribution of aerosols and water vapor are critical to the understanding of dust aerosol forcing. Using well calibrated, spatially and temporally collocated data sets, we have combined the strengths of three sensors from the same satellite to quantify the LW radiative forcing, and show that dust aerosols have a "warming" effect over the Saharan desert that will counteract the shortwave "cooling effect" of aerosols.

Ringed Structures of the HD 163296 Protoplanetary Disk Revealed by ALMA

NASA Astrophysics Data System (ADS)

Isella, Andrea; Guidi, Greta; Testi, Leonardo; Liu, Shangfei; Li, Hui; Li, Shengtai; Weaver, Erik; Boehler, Yann; Carperter, John M.; De Gregorio-Monsalvo, Itziar; Manara, Carlo F.; Natta, Antonella; Pérez, Laura M.; Ricci, Luca; Sargent, Anneila; Tazzari, Marco; Turner, Neal

2016-12-01

We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicate the presence of dust depleted gaps at about 60, 100, and 160 A.U. from the central star. The maps of the 12CO, 13CO, and C 18O J =2 -1 emission do not show such structures but reveal a change in the slope of the radial intensity profile across the positions of the dark rings in the continuum image. By comparing the observations with theoretical models for the disk emission, we find that the density of CO molecules is reduced inside the middle and outer dust gaps. However, in the inner ring there is no evidence of CO depletion. From the measurements of the dust and gas densities, we deduce that the gas-to-dust ratio varies across the disk and, in particular, it increases by at least a factor 5 within the inner dust gap compared to adjacent regions of the disk. The depletion of both dust and gas suggests that the middle and outer rings could be due to the gravitational torque exerted by two Saturn-mass planets orbiting at 100 and 160 A.U. from the star. On the other hand, the inner dust gap could result from dust accumulation at the edge of a magnetorotational instability dead zone, or from dust opacity variations at the edge of the CO frost line. Observations of the dust emission at higher angular resolution and of molecules that probe dense gas are required to establish more precisely the origins of the dark rings observed in the HD 163296 disk.

Martian Dust Aerosol Size and Shape as Constrained by Phoenix Lander Polarimetry

NASA Astrophysics Data System (ADS)

Lemmon, Mark T.; Mason, Emily L.

2014-11-01

Dust aerosol morphology is important to dust transport and the radiative heating of the Martian atmosphere. Previous analyses of Mars dust have shown that spherical particles are a bad analog for the dust, in terms of reproducing the distribution of scattered light. Parameterized scattering, based on laboratory observations of scattering by irregular dust particles, has been used for Viking, Pathfinder and Mars Exploration Rover data [Pollack et al., J. Geophys. Res. 100, 1995; Tomasko et al., J. Geophys. Res. 104, 1999; Lemmon et al., Science 306, 2004]. Analytical calculations have shown that cylinders are a better scattering analog than spheres [Wolff et al., J. Geophys. Res. 114, 2009]. Terrestrial studies have shown that a diverse assortment of triaxial ellipsoids is a good analog for dust aerosol [Bi et al., Applied Optics 48, 2009].The Phoenix Lander operated in the Martian arctic for 5 months of 2008, around the northern summer solstice. During the mission atmospheric optical depth was tracked through direct solar imaging by the Surface Stereo Imager (SSI). For solar longitude (Ls) 78-95 and 140-149, small dust storms dominated the weather. Low-dust conditions (optical depths <0.4) dominated during Ls 95-140, with sporadic ice clouds becoming more common after Ls 108. The SSI also obtained occasional cross-sky photometric data through several filters from 440 to 1000 nm and cross-sky polarimetry at 750 nm wavelength. Radiative transfer models of the sky radiance distribution are consistent with dust aerosols in the same 1.3-1.6 micron range reported for models of observations from previous missions. Cylinders, triaxial ellipsoids, and the parametric model can fit sky radiances; spheres cannot. The observed linear polarization, which reached 4-5% and had a similar angular distribution to Rayleigh polarization, is similar to the triaxial ellipsoid model, but not spheres or cylinders. An extension to the parametric model using 7-10% Rayleigh scattering mixed with unpolarized scattering is also an adequate model.

Ringed Structures of the HD 163296 Protoplanetary Disk Revealed by ALMA.

PubMed

Isella, Andrea; Guidi, Greta; Testi, Leonardo; Liu, Shangfei; Li, Hui; Li, Shengtai; Weaver, Erik; Boehler, Yann; Carperter, John M; De Gregorio-Monsalvo, Itziar; Manara, Carlo F; Natta, Antonella; Pérez, Laura M; Ricci, Luca; Sargent, Anneila; Tazzari, Marco; Turner, Neal

2016-12-16

We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicate the presence of dust depleted gaps at about 60, 100, and 160 A.U. from the central star. The maps of the ^{12}CO, ^{13}CO, and C^{18}O J=2-1 emission do not show such structures but reveal a change in the slope of the radial intensity profile across the positions of the dark rings in the continuum image. By comparing the observations with theoretical models for the disk emission, we find that the density of CO molecules is reduced inside the middle and outer dust gaps. However, in the inner ring there is no evidence of CO depletion. From the measurements of the dust and gas densities, we deduce that the gas-to-dust ratio varies across the disk and, in particular, it increases by at least a factor 5 within the inner dust gap compared to adjacent regions of the disk. The depletion of both dust and gas suggests that the middle and outer rings could be due to the gravitational torque exerted by two Saturn-mass planets orbiting at 100 and 160 A.U. from the star. On the other hand, the inner dust gap could result from dust accumulation at the edge of a magnetorotational instability dead zone, or from dust opacity variations at the edge of the CO frost line. Observations of the dust emission at higher angular resolution and of molecules that probe dense gas are required to establish more precisely the origins of the dark rings observed in the HD 163296 disk.

Infrared Luminosities and Dust Properties of z ≈ 2 Dust-obscured Galaxies

NASA Astrophysics Data System (ADS)

Bussmann, R. S.; Dey, Arjun; Borys, C.; Desai, V.; Jannuzi, B. T.; Le Floc'h, E.; Melbourne, J.; Sheth, K.; Soifer, B. T.

2009-11-01

We present SHARC-II 350 μm imaging of twelve 24 μm bright (F 24 μm > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1 mm imaging of a subset of two DOGs. These objects are selected from the Boötes field of the NOAO Deep Wide-Field Survey. Detections of four DOGs at 350 μm imply infrared (IR) luminosities which are consistent to within a factor of 2 of expectations based on a warm-dust spectral energy distribution (SED) scaled to the observed 24 μm flux density. The 350 μm upper limits for the 8 non-detected DOGs are consistent with both Mrk 231 and M82 (warm-dust SEDs), but exclude cold dust (Arp 220) SEDs. The two DOGs targeted at 1 mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T dust > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ≈3 × 108 M sun. In comparison to other dusty z ~ 2 galaxy populations such as submillimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2 × 1013 L sun versus 6 × 1012 L sun for the other galaxy populations) that are driven by warmer dust temperatures (>35-60 K versus ~30 K) and lower inferred dust masses (3 × 108 M sun versus 3 × 109 M sun). Wide-field Herschel and Submillimeter Common-User Bolometer Array-2 surveys should be able to detect hundreds of these power-law-dominated DOGs. We use the existing Hubble Space Telescope and Spitzer/InfraRed Array Camera data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24 μm bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although much larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z ~ 2 involves a submillimeter bright, cold-dust, and star-formation-dominated phase followed by a 24 μm bright, warm-dust and AGN-dominated phase.

MIRIS observation of near-infrared diffuse Galactic light

NASA Astrophysics Data System (ADS)

Onishi, Yosuke; Sano, Kei; Matsuura, Shuji; Jeong, Woong-Seob; Pyo, Jeonghyun; Kim, Il-Jong; Seo, Hyun Jong; Han, Wonyong; Lee, DaeHee; Moon, Bongkon; Park, Wonkee; Park, Younsik; Kim, MinGyu; Matsumoto, Toshio; Matsuhara, Hideo; Nakagawa, Takao; Tsumura, Kohji; Shirahata, Mai; Arai, Toshiaki; Ienaka, Nobuyuki

2018-06-01

We report near-infrared (IR) observations of high Galactic latitude clouds to investigate diffuse Galactic light (DGL), which is starlight scattered by interstellar dust grains. The observations were performed at 1.1 and 1.6 μm with a wide-field camera instrument, the Multi-purpose Infra-Red Imaging System (MIRIS) onboard the Korean satellite STSAT-3. The DGL brightness is measured by correlating the near-IR images with a far-IR 100 μm map of interstellar dust thermal emission. The wide-field observation of DGL provides the most accurate DGL measurement achieved to-date. We also find a linear correlation between optical and near-IR DGL in the MBM32 field. To study interstellar dust properties in MBM32, we adopt recent dust models with and without μm-sized very large grains and predict the DGL spectra, taking into account the reddening effect of the interstellar radiation field. The result shows that the observed color of the near-IR DGL is closer to the model spectra without very large grains. This may imply that dust growth in the observed MBM32 field is not active owing to the low density of its interstellar medium.

THEMIS Observations of Mars Aerosol Optical Depth from 2002-2008

NASA Technical Reports Server (NTRS)

Smith, Michael D.

2009-01-01

We use infrared images obtained by the Thermal Emission Imaging System (THEMIS) instrument on-board Mars Odyssey to retrieve the optical depth of dust and water ice aerosols over more than 3.5 martian years between February 2002 (MY 25, Ls=330 ) and December 2008 (MY 29, Ls=183). These data provide an important bridge between earlier TES observations and recent observations from Mars Express and Mars Reconnaissance Orbiter. An improvement to our earlier retrieval to include atmospheric temperature information from THEMIS Band 10 observations leads to much improved retrievals during the largest dust storms. The new retrievals show moderate dust storm activity during Mars Years 26 and 27, although details of the strength and timing of dust storms is different from year to year. A planet-encircling dust storm event was observed during Mars Year 28 near Southern Hemisphere Summer solstice. A belt of low-latitude water ice clouds was observed during the aphelion season during each year, Mars Years 26 through 29. The optical depth of water ice clouds is somewhat higher in the THEMIS retrievals at approximately 5:00 PM local time than in the TES retrievals at approximately 2:00 PM, suggestive of possible local time variation of clouds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarugaku, Yuki; Ueno, Munetaka; Ishiguro, Masateru

We report contemporaneous imaging observations of the short-period comet 2P/Encke in infrared and optical wavelengths during the 2003 return. Both images show the same unique morphology consisting of a spiky dust cloud near the nucleus and a dust trail extending along the orbit. We conducted a dynamical simulation of dust particles to characterize the morphology and found that dust particles were ejected intensively for a short duration (≲10 days) a few days after perihelion passage. The maximum particle size is at least on the order of 1 cm in radius following a differential power-law size distribution with an index ofmore » −3.2 to −3.6. The total mass ejected in the 2003 return is at least 1.5 × 10{sup 9}–1.2 × 10{sup 10} kg, which corresponds to 0.003%–0.03% of the nucleus mass. We derived the albedo of the dust cloud as 0.01–0.04 at a solar phase angle of 26.°2, which is consistent with or possibly greater than that of the nucleus. We suppose that impulsive activity such as an outburst is a key to understanding the peculiar appearance of 2P/Encke.« less

Results From an International Measurement Round Robin of III-V Triple-Junction Solar Cells Under Air Mass Zero

DTIC Science & Technology

2006-05-01

Loreto Pazos Bazán13, Sheila Bailey14 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) AND ADDRESS(ES) 8. PERFORMING...Toporow12, Trinidad Gómez13, Loreto Pazos Bazán13 Sheila Bailey14 1Ohio Aerospace Institute, 2QinetiQ, Cody Technology Park, 3Fraunhofer Institute

Hacking the Silos: Eliminating Information Barriers Between Public Health and Law Enforcement

DTIC Science & Technology

2018-03-01

ELIMINATING INFORMATION BARRIERS BETWEEN PUBLIC HEALTH AND LAW ENFORCEMENT by Cody L. Minks March 2018 Thesis Advisor: Anke Richter...burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching...existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information . Send comments regarding this

Forensic DNA Profiling and Database

PubMed Central

Panneerchelvam, S.; Norazmi, M.N.

2003-01-01

The incredible power of DNA technology as an identification tool had brought a tremendous change in crimnal justice . DNA data base is an information resource for the forensic DNA typing community with details on commonly used short tandem repeat (STR) DNA markers. This article discusses the essential steps in compilation of COmbined DNA Index System (CODIS) on validated polymerase chain amplified STRs and their use in crime detection. PMID:23386793

Marine Structural Steel Toughness Data Bank. Volume 4

DTIC Science & Technology

1990-08-31

Break? Did specimen fracture completely? CODIc Critical COD CODi Initial COD CVN Energy Charpy V Energy Crack lgth Crack Length Curve Curve Shape DT...Onien Test Temp COIi CODIc i1 imax Tear Mod degF in In in-lb/in**2 in-lb/in**2 in-lb/in**2 L-T 72 0.0236 0.0380 4346 4315 260.2 L-T 72

Carbohydrate and protein contents of grain dusts in relation to dust morphology.

PubMed Central

Dashek, W V; Olenchock, S A; Mayfield, J E; Wirtz, G H; Wolz, D E; Young, C A

1986-01-01

Grain dusts contain a variety of materials which are potentially hazardous to the health of workers in the grain industry. Because the characterization of grain dusts is incomplete, we are defining the botanical, chemical, and microbial contents of several grain dusts collected from grain elevators in the Duluth-Superior regions of the U.S. Here, we report certain of the carbohydrate and protein contents of dusts in relation to dust morphology. Examination of the gross morphologies of the dusts revealed that, except for corn, each dust contained either husk or pericarp (seed coat in the case of flax) fragments in addition to respirable particles. When viewed with the light microscope, the fragments appeared as elongated, pointed structures. The possibility that certain of the fragments within corn, settled, and spring wheat were derived from cell walls was suggested by the detection of pentoses following colorimetric assay of neutralized 2 N trifluoroacetic acid hydrolyzates of these dusts. The presence of pentoses together with the occurrence of proteins within water washings of grain dusts suggests that glycoproteins may be present within the dusts. With scanning electron microscopy, each dust was found to consist of a distinct assortment of particles in addition to respirable particles. Small husk fragments and "trichome-like" objects were common to all but corn dust. Images FIGURE 4. FIGURE 5. PMID:3709476

Mid-Infrared Interferometry on Spectral Lines. II. Continuum (Dust) Emission Around IRC +10216 and VY Canis Majoris

NASA Astrophysics Data System (ADS)

Monnier, J. D.; Danchi, W. C.; Hale, D. S.; Lipman, E. A.; Tuthill, P. G.; Townes, C. H.

2000-11-01

The University of California Berkeley Infrared Spatial Interferometer has measured the mid-infrared visibilities of the carbon star IRC +10216 and the red supergiant VY CMa. The dust shells around these sources have been previously shown to be time variable, and these new data are used to probe the evolution of the dust shells on a decade timescale, complementing contemporaneous studies at other wavelengths. Self-consistent, spherically symmetric models at maximum and minimum light both show the inner radius of the IRC +10216 dust shell to be much larger (150 mas) than expected from the dust-condensation temperature, implying that dust production has slowed or stopped in recent years. Apparently, dust does not form every pulsational cycle (638 days), and these mid-infrared results are consistent with recent near-infrared imaging, which indicates little or no new dust production in the last 3 yr. Spherically symmetric models failed to fit recent VY CMa data, implying that emission from the inner dust shell is highly asymmetric and/or time variable.

The Herschel Virgo Cluster Survey. XIII. Dust in early-type galaxies

NASA Astrophysics Data System (ADS)

di Serego Alighieri, S.; Bianchi, S.; Pappalardo, C.; Zibetti, S.; Auld, R.; Baes, M.; Bendo, G.; Corbelli, E.; Davies, J. I.; Davis, T.; De Looze, I.; Fritz, J.; Gavazzi, G.; Giovanardi, C.; Grossi, M.; Hunt, L. K.; Magrini, L.; Pierini, D.; Xilouris, E. M.

2013-04-01

Aims: We study the dust content of a large optical input sample of 910 early-type galaxies (ETG) in the Virgo cluster, also extending to the dwarf ETG, and examine the results in relation to those on the other cold ISM components. Methods: We have searched for far-infrared emission in all galaxies in the input sample using the 250 μm image of the Herschel Virgo Cluster Survey (HeViCS). This image covers a large fraction of the cluster with an area of ~55 square degrees. For the detected ETG we measured fluxes in five bands from 100 to 500 μm, and estimated the dust mass and temperature with modified black-body fits. Results: Dust is detected above the completeness limit of 25.4 mJy at 250 μm in 46 ETG, 43 of which are in the optically complete part of the input sample. In addition, dust is present at fainter levels in another six ETG. We detect dust in the four ETG with synchrotron emission, including M 87. Dust appears to be much more concentrated than stars and more luminous ETG have higher dust temperatures. Considering only the optically complete input sample and correcting for the contamination by background galaxies, dust detection rates down to the 25.4 mJy limit are 17% for ellipticals, about 40% for lenticulars (S0 + S0a), and around 3% for dwarf ETG. Dust mass does not correlate clearly with stellar mass and is often much greater than expected for a passive galaxy in a closed-box model. The dust-to-stars mass ratio anticorrelates with galaxy luminosity, and for some dwarf ETG reaches values as high as for dusty late-type galaxies. In the Virgo cluster slow rotators appear more likely to contain dust than fast ones. Comparing the dust results with those on Hi there are only eight ETG detected both in dust and in Hi in the HeViCS area; 39 have dust but only an upper limit on Hi, and eight have Hi but only an upper limit on dust. The locations of these galaxies in the cluster are different, with the dusty ETG concentrated in the densest regions, while the Hi rich ETG are at the periphery. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Table A.1 is available in electronic form at http://www.aanda.org

Images of the 10-micron source in the Cygnus 'Egg'

NASA Technical Reports Server (NTRS)

Jaye, D.; Fienberg, R. Tresch; Fazio, G. G.; Gezari, D. Y.; Lamb, G. M.; Shu, P. K.; Hoffmann, W. F.; Mccreight, C. R.

1989-01-01

Mid-IR images of AFGL 2688, the Egg nebula, obtained with a 16 x 16 pixel array camera (field of view 12.5 x 12.5 arcsec) resolve the central source. It appears as a centrally peaked ellipsoid with major axis of symmetry parallel to the axis of the visible nebulosity. This is contrary to the expected extension perpendicular to this axis implied by proposed dust-toroid models of the IR source. Maps of the spatial distribution of 8-13 micron color temperature and warm dust opacity derived from the multiwavelength images further characterize the IR emission. The remarkable flatness of the color temperature conflicts with the radial temperature gradient expected across a thick shell of material with a single heat source at its center. The new data suggest instead that the source consists of a central star surrounded by a dust shell that is too thin to provide a detectable temperature gradient and too small to permit the resolution of limb brightening.

Circles and Streaks

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-544, 14 November 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired less than a week ago on 8 November 2003, shows a typical southern middle-to-high latitude scene at this time of year. It is summer in the southern hemisphere, and regions such as Promethei Terra, where this image was acquired, are being streaked by dust devils that remove or disrupt the coating of dust that was deposited over the region in the previous autumn or winter. While no active dust devils were captured in this scene, their tell-tale tracks are scratched all across the image. The circular features are the sites of buried meteor impact craters; their rims form dark rings; the material that fills the craters has become cracked. This picture is located near 68.1oS, 247.9oW. The area shown is approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.

Dust in the wind: long range transport of dust in the atmosphere and its implications for global public and ecosystem health

USGS Publications Warehouse

Griffin, Dale W.; Kellogg, Christina A.; Shinn, Eugene A.

2001-01-01

Movement of soil particles in atmospheres is a normal planetary process. Images of Martian dust devils (wind-spouts) and dust storms captured by NASA's Pathfinder have demonstrated the significant role that storm activity plays in creating the red atmospheric haze of Mars. On Earth, desert soils moving in the atmosphere are responsible for the orange hues in brilliant sunrises and sunsets. In severe dust storm events, millions of tons of soil may be moved across great expanses of land and ocean. An emerging scientific interest in the process of soil transport in the Earth's atmosphere is in the field of public and ecosystem health. This article will address the benefits and the potential hazards associated with exposure to particle fallout as clouds of desert dust traverse the globe.

Identification of dust source regions and dust emission trends across North Africa and the Middle East using MISR satellite observations

NASA Astrophysics Data System (ADS)

Yu, Y.; Kalashnikova, O. V.; Garay, M. J.; Notaro, M.

2017-12-01

Global arid and semi-arid regions supply 1100 to 5000 Tg of Aeolian dust to the atmosphere each year, primarily from North Africa and secondarily from the Middle East. Previous dust source identification methods, based on either remotely-sensed aerosol optical depth (AOD) or dust activity, yield distinct dust source maps, largely due to the limitations in each method and remote-sensing product. Here we apply a novel motion-based method for dust source identification. Dust plume thickness and motion vectors from Multi-angle Imaging SpectroRadiometer (MISR) Cloud Motion Vector Product (CMVP) are examined to identify the regions with high frequency of fast moving-dust plumes, by season. According to MISR CMVP, Bodele depression is the most important dust source across North Africa, consistent with previous studies. Seasonal variability of dust emission across the North Africa is largely driven by climatology of wind and precipitation, featuring the influence of Sharav Cyclone and western African monsoon. In the Middle East, Iraq, Kuwait, and eastern Saudi Arabia are identified as dust source regions, especially during summer months, when the Middle Eastern Shamal wind is active. Furthermore, dust emission trend at each dust source are diagnosed from the motion-based dust source dataset. Increase in dust emission from the Fertile Crescent, Sahel, and eastern African dust sources are identified from MISR CMVP, implying potential contribution from these dust sources to the upward trend in AOD and dust AOD over the Middle East in the 21st century. By comparing with various dust source identification studies, we conclude that the motion-based identification of dust sources is an encouraging alternative and compliment to the AOD-only source identification method.

A Hubble Study of the Peculiar Asymmetry of NGC 949

NASA Image and Video Library

2015-05-08

This image provides the clearest ever view of galaxy NGC 949, which lies over 30 million light-years away in the constellation of Triangulum. The galaxy has an unusual shape, made more obscure due to its inclination. From our point of view, it is difficult to discern exactly what type of galaxy NGC 949 is, but it is certainly a disk galaxy of some kind, most likely a spiral. NGC 949 was first discovered by Sir William Herschel on September 21, 1786, using an 18.7-inch reflecting telescope. The galaxy was one of about 3,000 objects Herschel cataloged as "nebulae" during an intense and systematic deep sky survey, the results of which eventually formed the bulk of the New General Catalogue (NGC). Taken with Hubble’s Advanced Camera for Surveys (ACS), this image shows extraordinary detail. This detail allows us to see a strange asymmetric alignment in the dark lanes of dust that snake across the galaxy. The top-right half of the galaxy appears considerably more marbled with dust in this image; a curious observation explained by stars tending to favor locations towards the center of a galaxy, and dust preferring almost invariably to reside along the galactic plane. When a galaxy is inclined as NGC 949 is, some regions — in this case the top-right — are tipped toward us and the light from the stars we see in these regions has had to travel through more dust. This causes the light to appear redder — the result of the same process that gives the sun’s light a red hue at dusk — or else disappear entirely, making the dust appear more prominent on that side of the galaxy. In the part tipped away from us, the light from the stars has had to pass through much less dust to reach us, so it appears brighter, and the dust is much less prominent. Were it possible to view NGC 949 from the opposite side, the apparent alignment of the dust would be reversed. The scientific advantages of this effect were recently displayed in suitably stunning style in the M31 PHAT mosaic, which allowed astronomers to produce a partial three-dimensional dust map of M31 four times clearer than any previously attempted. Credit: ESA/Hubble & NASA NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

HST Imaging of Dust Structures and Stars in the Ram Pressure Stripped Virgo Spirals NGC 4402 and NGC 4522: Stripped from the Outside In with Dense Cloud Decoupling

NASA Astrophysics Data System (ADS)

Abramson, A.; Kenney, J.; Crowl, H.; Tal, T.

2016-08-01

We describe and constrain the origins of interstellar medium (ISM) structures likely created by ongoing intracluster medium (ICM) ram pressure stripping in two Virgo Cluster spirals, NGC 4522 and NGC 4402, using Hubble Space Telescope (HST) BVI images of dust extinction and stars, as well as supplementary H I, Hα, and radio continuum images. With a spatial resolution of ˜10 pc in the HST images, this is the highest-resolution study to date of the physical processes that occur during an ICM-ISM ram pressure stripping interaction, ram pressure stripping's effects on the multi-phase, multi-density ISM, and the formation and evolution of ram-pressure-stripped tails. In dust extinction, we view the leading side of NGC 4402 and the trailing side of NGC 4522, and so we see distinct types of features in both. In both galaxies, we identify some regions where dense clouds are decoupling or have decoupled and others where it appears that kiloparsec-sized sections of the ISM are moving coherently. NGC 4522 has experienced stronger, more recent pressure and has the “jellyfish” morphology characteristic of some ram-pressure-stripped galaxies. Its stripped tail extends up from the disk plane in continuous upturns of dust and stars curving up to ˜2 kpc above the disk plane. On the other side of the galaxy, there is a kinematically and morphologically distinct extraplanar arm of young, blue stars and ISM above a mostly stripped portion of the disk, and between it and the disk plane are decoupled dust clouds that have not been completely stripped. The leading side of NGC 4402 contains two kiloparsec-scale linear dust filaments with complex substructure that have partially decoupled from the surrounding ISM. NGC 4402 also contains long dust ridges, suggesting that large parts of the ISM are being pushed out at once. Both galaxies contain long ridges of polarized radio continuum emission indicating the presence of large-scale, ordered magnetic fields. We propose that magnetic fields could bind together gas of different densities, causing nearby gas of different densities to be stripped at the same rate and creating the large, coherent dust ridges and upturns. A number of factors likely play roles in determining what types of structures form as a result of ram pressure, including ram pressure strength and history, the location within the galaxy relative to the leading side, and pre-existing substructure in the ISM that may be bound together by magnetic fields during stripping.

Fingerprints in the Dust

NASA Technical Reports Server (NTRS)

2001-01-01

These MISR nadir-camera images of eastern China compare a somewhat hazy summer view from July 9, 2000 (left) with a spectacularly dusty spring view from April 7, 2001 (middle). The left-hand and middle images are from Terra orbits 2967 and 6928, respectively, and extend from central Manchuria near the top to portions of North and South Korea at the bottom. They are approximately 380 kilometers in width.

Asia's desert areas are prone to soil erosion, as underground water tables are lowered by prolonged drought and by industrial and agricultural water use. Heavy winds blowing eastward across the arid and sparsely vegetated surfaces of Mongolia and western China pick up large quantities of yellow dust. Airborne dust clouds from the April 2001 storm blew across the Pacific Ocean and were carried as far as North America. The minerals transported in this manner are believed to provide nutrients for both oceanic and land ecosystems.

According to the Xinhua News Agency in China, nearly one million tons of Gobi Desert dust blow into Beijing each year. During a similar dust outbreak last year, the Associated Press reported that the visibility in Beijing had been reduced the point where buildings were barely visible across city streets, and airline schedules were significantly disrupted. The dust has also been implicated in adverse health effects such as respiratory discomfort and eye irritation.

The image on the right is a higher resolution MISR nadir-camera view of a portion of the April 7, 2001 dust cloud. It covers an area roughly 250 kilometers wide by 470 kilometers high. When viewed at full magnification, a number of atmospheric wave features, like the ridges and valleys of a fingerprint, are apparent. These are probably induced by surface topography, which can disturb the wind flow. A few small cumulus clouds are also visible, and are casting shadows on the thick lower dust layer.

Analyses of images such as these constitute one phase of MISR's participation in the Asian-Pacific Regional Aerosol Characterization Experiment, an international campaign aimed at studying the offshore transport of airborne particles from the Asian continent. For more about this international endeavor, see http://saga.pmel.noaa.gov/aceasia/.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

Thermal emission from interstellar dust in and near the Pleiades

NASA Technical Reports Server (NTRS)

White, Richard E.

1989-01-01

IRAS survey coadds for a 8.7 deg x 4.3 deg field near the Pleiades provide evidence for dynamical interaction between the cluster and the surrounding interstellar medium. The far-infrared images show large region of faint emission with bright rims east of the cluster, suggestive of a wake. Images of the far-infrared color temperature and 100 micron optical depth reveal temperature maxima and optical depth minima near the bright cluster stars, as well as a strong optical depth peak at the core of the adjacent CO cloud. Models for thermal dust emission near the stars indicate that most of the apparent optical depth minima near stars are illusory, but also provide indirect evidence for small interaction between the stars and the encroaching dust cloud.

Valley Near Nilus Chaos

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-504, 5 October 2003

This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a valley near Nilus Chaos, around 25.2oN, 80.3oW. The scene has a uniform albedo, indicating that all of the landforms are probably mantled by fine, bright dust. Dark streaks on the valley walls indicate places where recent dust avalanches have occurred. The ripple-like dune features on the valley floor were formed by wind, but today they are inactive and covered with dust. A few craters, created by impacting debris, have formed on the dunes, again attesting to their inactivity in the modern martian environment. The image covers an area 3 km (1.9 mi) wide; it is illuminated by sunlight from the lower left.

Three mars years: Viking lander 1 imaging observations

USGS Publications Warehouse

Arvidson, R. E.; Guinness, E.A.; Moore, H.J.; Tillman, J.; Wall, S.D.

1983-01-01

The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3:3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohesion of the undisturbed surface material.

Three Mars years: viking lander 1 imaging observations.

PubMed

Arvidson, R E; Guinness, E A; Moore, H J; Tillman, J; Wall, S D

1983-11-04

The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3:3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohesion of the undisturbed surface material.

Three Mars years - Viking Lander 1 imaging observations

NASA Technical Reports Server (NTRS)

Arvidson, R. E.; Guinness, E. A.; Moore, H. J.; Tillman, J.; Wall, S. D.

1983-01-01

The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3.3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohension of the undisturbed surface material.

Dust Storm over the Middle East: Retrieval Approach, Source Identification, and Trend Analysis

NASA Astrophysics Data System (ADS)

Moridnejad, A.; Karimi, N.; Ariya, P. A.

2014-12-01

The Middle East region has been considered to be responsible for approximately 25% of the Earth's global emissions of dust particles. By developing Middle East Dust Index (MEDI) and applying to 70 dust storms characterized on MODIS images and occurred during the period between 2001 and 2012, we herein present a new high resolution mapping of major atmospheric dust source points participating in this region. To assist environmental managers and decision maker in taking proper and prioritized measures, we then categorize identified sources in terms of intensity based on extracted indices for Deep Blue algorithm and also utilize frequency of occurrence approach to find the sensitive sources. In next step, by implementing the spectral mixture analysis on the Landsat TM images (1984 and 2012), a novel desertification map will be presented. The aim is to understand how human perturbations and land-use change have influenced the dust storm points in the region. Preliminary results of this study indicate for the first time that c.a., 39 % of all detected source points are located in this newly anthropogenically desertified area. A large number of low frequency sources are located within or close to the newly desertified areas. These severely desertified regions require immediate concern at a global scale. During next 6 months, further research will be performed to confirm these preliminary results.

Monitoring of Saharan dust fallout on Crete and its contribution to soil formation

NASA Astrophysics Data System (ADS)

Nihlén, Tomas; Mattsson, Jan O.; Rapp, Anders; Gagaoudaki, Chrisoula; Kornaros, Georges; Papageorgiou, John

1995-07-01

A series of 6 dust traps was established in 1988 distributed over the island of Crete (Greece). Eolian dust has been collected in the traps each year and in each season during the 4years of investigation which is still going on. The mean deposition rate for the 6 stations and 4years was calculated as 21.3g m2yr1. Using the highest and lowest values, the deposition can be extrapolated to 6.6-21.4mm for 1000years, which is in agreement with other researchers' findings. The trapped dust shows a homogeneous grain-size distribution. Its mineralogy is similar to what characterizes soil samples from Psiloritis on Crete and source areas in southern Tunisia. In the fine fraction of the soil (particles < 10µm), the contents of the clay mineral kaolinite and of quartz are high. In addition, the oxygen isotope composition of the 3 types of substrate is similar but differs from the weathering products of the limestone bedrock. Statistics of dust episodes covering the period c. 1955-1990 from 10 meteorological stations in Greece revealed that long-distance transport of dust in combination with winds from a southerly sector is common in the Aegean area during spring.

Dust Removal on Mars Using Laser-Induced Breakdown Spectroscopy

NASA Technical Reports Server (NTRS)

Graff, T. G.; Morris, R. V.; Clegg, S. M.; Wiens, R. C.; Anderson, R. B.

2011-01-01

Dust coatings on the surface of Mars complicate and, if sufficiently thick, mask the spectral characteristics and compositional determination of underlying material from in situ and remote sensing instrumentation. The Laser-Induced Breakdown Spectroscopy (LIBS) portion of the Chemistry & Camera (ChemCam) instrument, aboard the Mars Science Laboratory (MSL) rover, will be the first active remote sensing technique deployed on Mars able to remove dust. ChemCam utilizes a 5 ns pulsed 1067 nm high-powered laser focused to less than 400 m diameter on targets at distances up to 7 m [1,2]. With multiple laser pulses, dust and weathering coatings can be remotely analyzed and potentially removed using this technique [2,3]. A typical LIBS measurement during MSL surface operations is planned to consist of 50 laser pulses at 14 mJ, with the first 5 to 10 pulses used to analyze as well as remove any surface coating. Additionally, ChemCam's Remote Micro-Imager (RMI) is capable of resolving 200 m details at a distance of 2 m, or 1 mm at 10 m [1,4]. In this study, we report on initial laboratory experiments conducted to characterize the removal of dust coatings using similar LIBS parameters as ChemCam under Mars-like conditions. These experiments serve to better understand the removal of surface dust using LIBS and to facilitate the analysis of ChemCam LIBS spectral data and RMI images.

Unraveling the Mystery of Exozodiacal Dust

NASA Astrophysics Data System (ADS)

Ertel, S.; Augereau, J.-C.; Thébault, P.; Absil, O.; Bonsor, A.; Defrère, D.; Kral, Q.; Le Bouquin, J.-B.; Lebreton, J.; Coudé du Foresto, V.

2014-01-01

Exozodiacal dust clouds are thought to be the extrasolar analogs of the Solar System's zodiacal dust. Studying these systems provides insights in the architecture of the innermost regions of planetary systems, including the Habitable Zone. Furthermore, the mere presence of the dust may result in major obstacles for direct imaging of earth-like planets. Our EXOZODI project aims to detect and study exozodiacal dust and to explain its origin. We are carrying out the first large, near-infrared interferometric survey in the northern (CHARA/FLUOR) and southern (VLTI/PIONIER) hemispheres. Preliminary results suggest a detection rate of up to 30% around A to K type stars and interesting trends with spectral type and age. We focus here on presenting the observational work carried out by our team.

Adhesion of Lunar Dust

NASA Astrophysics Data System (ADS)

Walton, Otis R.

2007-04-01

This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

Dust Storm Covers Opportunity

NASA Image and Video Library

2018-06-10

This global map of Mars shows a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter spacecraft. The blue dot shows the approximate location of Opportunity. The storm was first detected on June 1. The MARCI camera has been used to monitor the storm ever since. Full dust storms like this one are not surprising, but are infrequent. They can crop up suddenly but last weeks, even months. During southern summer, sunlight warms dust particles, lifting them higher into the atmosphere and creating more wind. That wind kicks up yet more dust, creating a feedback loop that NASA scientists still seek to understand. https://photojournal.jpl.nasa.gov/catalog/PIA22329

A new method to generate dust with astrophysical properties

NASA Astrophysics Data System (ADS)

Hansen, J. F.; van Breugel, W.; Bringa, E. M.; Eberly, B.; Graham, G. A.; Remington, B. A.; Taylor, E. A.; Tielens, A. G. G. M.

2011-05-01

To model the size distribution and composition of interstellar and interplanetary dust grains, and their effect on a wide range of phenomena, it is vital to understand the mechanism of dust-shock interaction. We demonstrate a new laser experiment that subjects dust grains to pressure spikes similar to those of colliding astrophysical dust, and that accelerates the grains to astrophysical velocities. This new method generates much larger data sets than earlier methods; we show how large quantities (thousands) of grains are accelerated at once, rather than accelerating individual grains, as is the case of earlier methods using electric fields. We also measure the in-flight velocity ( ~ 4.5km/s) of hundreds of grains simultaneously by use of a particle image velocimetry (PIV) technique.

The Micro Imaging and Dust Analysis System - New Possibilities for Space Sciences

NASA Astrophysics Data System (ADS)

Schmied, R.; Torkar, K..; Jeszenszky, H.; Romstedt, J.; Mannel, T.; Bentley, M. S.

2015-10-01

The Rosetta mission addresses a range of fundamental questions in Solar System and cometary science and the MIDAS instrument on-board the orbiter is one of the dust analysis systems. While GIADA analyses the dust flux and spatial distribution as a function of time and space and COSIMA investigates the elemental composition of cometary grains, MIDAS is a unique high resolution Atomic Force Microscope (AFM) combined with a dust collection and handling system designed to reveal the three-dimensional topographical structure of nanoand micrometer sized dust particles [1]. In this work we concentrate on the instrumental functionality and limitations coming from the constcution and operation dealing with an AFM fabricated nearly 20 years ago and operating in a harsh environment.

Adhesion of Lunar Dust

NASA Technical Reports Server (NTRS)

Walton, Otis R.

2007-01-01

This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

MGS Approach Image - 352.2o W longitude

NASA Technical Reports Server (NTRS)

1997-01-01

The bright area at the center of this view of Mars taken by the MGS/MOC is called Arabia. It contains some of the brightest ground on Mars, thought to be especially deep or fresh dust deposits. Syrtis Major, the dark feature curving north-south near the center edge of the planet, is devoid of large amounts of dust, probably because sand moves for frequently there and kicks up the dust into the martian air where it can be transported away. The dark 'splotches' near the middle top of the image are small sand dune fields trapped in the depressions of the Protonilus and Nilosyrtis 'fretted terrain' (a zone of valleys formed by tectonic fracturing and subsequent erosion). In the lower portion of the image is Terra Sabaea, a heavily cratered area near regions where major dust storms occur. The light, semicircular indentation is the 480 km diameter crater Schiaparelli.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

Smoke Ring for a Halo

NASA Image and Video Library

2017-12-08

Two stars shine through the center of a ring of cascading dust in this image taken by the NASA/ESA Hubble Space Telescope. The star system is named DI Cha, and while only two stars are apparent, it is actually a quadruple system containing two sets of binary stars. As this is a relatively young star system it is surrounded by dust. The young stars are molding the dust into a wispy wrap. The host of this alluring interaction between dust and star is the Chamaeleon I dark cloud — one of three such clouds that comprise a large star-forming region known as the Chamaeleon Complex. DI Cha's juvenility is not remarkable within this region. In fact, the entire system is among not only the youngest but also the closest collections of newly formed stars to be found and so provides an ideal target for studies of star formation. Image credit: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The Sword of Orion

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] [figure removed for brevity, see original site] AnimationFigure 1

This infrared image from NASA's Spitzer Space Telescope shows the Orion nebula, our closest massive star-making factory, 1,450 light-years from Earth. The nebula is close enough to appear to the naked eye as a fuzzy star in the sword of the popular hunter constellation.

The nebula itself is located on the lower half of the image, surrounded by a ring of dust. It formed in a cold cloud of gas and dust and contains about 1,000 young stars. These stars illuminate the cloud, creating the beautiful nebulosity, or swirls of material, seen here in infrared.

In the center of the nebula (bottom inset of figure 1) are four monstrously massive stars, up to 100,000 times as luminous as our sun, called the Trapezium (tiny yellow smudge to the lower left of green splotches. Radiation and winds from these stars are blasting gas and dust away, excavating a cavity walled in by the large ring of dust.

Behind the Trapezium, still buried deeply in the cloud, a second generation of massive stars is forming (in the area with green splotches). The speckled green fuzz in this bright region is created when bullets of gas shoot out from the juvenile stars and ram into the surrounding cloud.

Above this region of intense activity are networks of cold material that appear as dark veins against the pinkish nebulosity (upper inset pf figure 1). These dark veins contain embryonic stars. Some of the natal stars illuminate the cloud, creating small, aqua-colored wisps. In addition, jets of gas from the stars ram into the cloud, resulting in the green horseshoe-shaped globs.

Spitzer surveyed a significant swath of the Orion constellation, beyond what is highlighted in this image. Within that region, called the Orion cloud complex, the telescope found 2,300 stars circled by disks of planet-forming dust and 200 stellar embryos too young to have developed disks.

This image shows infrared light captured by Spitzer's infrared array camera. Light with wavelengths of 8 and 5.8 microns (red and orange) comes mainly from dust that has been heated by starlight. Light of 4.5 microns (green) shows hot gas and dust; and light of 3.6 microns (blue) is from starlight.

Adapting MODIS Dust Mask Algorithm to Suomi NPP VIIRS for Air Quality Applications

NASA Astrophysics Data System (ADS)

Ciren, P.; Liu, H.; Kondragunta, S.; Laszlo, I.

2012-12-01

Despite pollution reduction control strategies enforced by the Environmental Protection Agency (EPA), large regions of the United States are often under exceptional events such as biomass burning and dust outbreaks that lead to non-attainment of particulate matter standards. This has warranted the National Weather Service (NWS) to provide smoke and dust forecast guidance to the general public. The monitoring and forecasting of dust outbreaks relies on satellite data. Currently, Aqua/MODIS (MODerate resolution Imaging Spectrometer) and Terra/MODIS provide measurements needed to derive dust mask and Aerosol Optical Thickness (AOT) products. The newly launched Suomi NPP VIIRS (Visible/Infrared Imaging Radiometer Suite) instrument has a Suspended Matter (SM) product that indicates the presence of dust, smoke, volcanic ash, sea salt, and unknown aerosol types in a given pixel. The algorithm to identify dust is different over land and ocean but for both, the information comes from AOT retrieval algorithm. Over land, the selection of dust aerosol model in the AOT retrieval algorithm indicates the presence of dust and over ocean a fine mode fraction smaller than 20% indicates dust. Preliminary comparisons of VIIRS SM to CALIPSO Vertical Feature Mask (VFM) aerosol type product indicate that the Probability of Detection (POD) is at ~10% and the product is not mature for operational use. As an alternate approach, NESDIS dust mask algorithm developed for NWS dust forecast verification that uses MODIS deep blue, visible, and mid-IR channels using spectral differencing techniques and spatial variability tests was applied to VIIRS radiances. This algorithm relies on the spectral contrast of dust absorption at 412 and 440 nm and an increase in reflectivity at 2.13 μm when dust is present in the atmosphere compared to a clear sky. To avoid detecting bright desert surface as airborne dust, the algorithm uses the reflectances at 1.24 μm and 2.25 μm to flag bright pixels. The algorithm flags pixels that fall into the glint region so sun glint is not picked up as dust. The algorithm also has a spatial variability test that uses reflectances at 0.86 μm to screen for clouds over water. Analysis of one granule for a known dust event on May 2, 2012 shows that the agreement between VIIRS and MODIS is 82% and VIIRS and CALIPSO is 71%. The probability of detection for VIIRS when compared to MODIS and CALIPSO is 53% and 45% respectively whereas the false alarm ratio for VIIRS when compared to MODIS and CALIPSO is 20% and 37% respectively. The algorithm details, results from the test cases, and the use of the dust flag product in NWS applications will be presented.

The Effect of Asian Dust Aerosols on Cloud Properties and Radiative Forcing from MODIS and CERES

NASA Technical Reports Server (NTRS)

Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

2005-01-01

The effects of dust storms on cloud properties and radiative forcing are analyzed over northwestern China from April 2001 to June 2004 using data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of the cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. The humidity differences are larger in the dusty region than in the dust-free region, and may be caused by removal of moisture by wet dust precipitation. Due to changes in cloud microphysics, the instantaneous net radiative forcing is reduced from -71.2 W/m2 for dust contaminated clouds to -182.7 W/m2 for dust-free clouds. The reduced cooling effects of dusts may lead to a net warming of 1 W/m2, which, if confirmed, would be the strongest aerosol forcing during later winter and early spring dust storm seasons over the studied region.

MISR Decadal Observations of Mineral Dust: Property Characterization and Climate Applications

NASA Technical Reports Server (NTRS)

Kalashnikova, Olga V.; Garay, Michael J.; Sokolik, Irina; Kahn, Ralph A.; Lyapustin, A.; Diner, David J.; Lee, Jae N.; Torres, Omar; Leptoukh, Gregory G.; Sabbah, Ismail

2012-01-01

The Multi-angle Imaging SpectroRadiometer (MISR) provides a unique, independent source of data for studying dust emission and transport. MISR's multiple view angles allow the retrieval of aerosol properties over bright surfaces, and such retrievals have been shown to be sensitive to the non-sphericity of dust aerosols over both land and water. MISR stereographic views of thick aerosol plumes allow height and instantaneous wind derivations at spatial resolutions of better than 1.1 km horizontally and 200m vertically. We will discuss the radiometric and stereo-retrieval capabilities of MISR specifically for dust, and demonstrate the use of MISR data in conjunction with other available satellite observations for dust property characterization and climate studies.First, we will discuss MISR non-spherical (dust) fraction product over the global oceans. We will show that over the Atlantic Ocean, changes in the MISR-derived non-spherical AOD fraction illustrate the evolution of dust during transport. Next, we will present a MISR satellite perspective on dust climatology in major dust source regions with a particular emphasis on the West Africa and Middle East and discuss MISR's unique strengths as well as current product biases. Finally, we will discuss MISR dust plume product and climatological applications.

Clouds Over the North Pole

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site]

Released 29 June 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

Like yesterday's image, the linear 'ripples' are water-ice clouds. As spring is deepening at the North Pole these clouds are becoming more prevalent.

Image information: VIS instrument. Latitude 68.9, Longitude 135.5 East (224.5 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

What's Old is New in the Large Magellanic Cloud

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] Poster Version Large Magellanic Cloud

This vibrant image from NASA's Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy.

The infrared image, a mosaic of 300,000 individual tiles, offers astronomers a unique chance to study the lifecycle of stars and dust in a single galaxy. Nearly one million objects are revealed for the first time in this Spitzer view, which represents about a 1,000-fold improvement in sensitivity over previous space-based missions. Most of the new objects are dusty stars of various ages populating the Large Magellanic Cloud; the rest are thought to be background galaxies.

The blue color in the picture, seen most prominently in the central bar, represents starlight from older stars. The chaotic, bright regions outside this bar are filled with hot, massive stars buried in thick blankets of dust. The red color around these bright regions is from dust heated by stars, while the red dots scattered throughout the picture are either dusty, old stars or more distant galaxies. The greenish clouds contain cooler interstellar gas and molecular-sized dust grains illuminated by ambient starlight.

Astronomers say this image allows them to quantify the process by which space dust -- the same stuff that makes up planets and even people -- is recycled in a galaxy. The picture shows dust at its three main cosmic hangouts: around the young stars, where it is being consumed (red-tinted, bright clouds); scattered about in the space between stars (greenish clouds); and in expelled shells of material from old stars (randomly-spaced red dots).

The Large Magellanic Cloud, located 160,000 light-years from Earth, is one of a handful of dwarf galaxies that orbit our own Milky Way. It is approximately one-third as wide as the Milky Way, and, if it could be seen in its entirety, would cover the same amount of sky as a grid of about 480 full moons. About one-third of the entire galaxy can be seen in the Spitzer image.

This picture is a composite of infrared light captured by Spitzer. Light with wavelengths of 3.6 (blue) and 8 (green) microns was captured by the telescope's infrared array camera; 24-micron light (red) was detected by the multiband imaging photometer.

What Old is New in the Large Magellanic Cloud

NASA Image and Video Library

2006-09-01

This vibrant image from NASA's Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy. The infrared image, a mosaic of 300,000 individual tiles, offers astronomers a unique chance to study the lifecycle of stars and dust in a single galaxy. Nearly one million objects are revealed for the first time in this Spitzer view, which represents about a 1,000-fold improvement in sensitivity over previous space-based missions. Most of the new objects are dusty stars of various ages populating the Large Magellanic Cloud; the rest are thought to be background galaxies. The blue color in the picture, seen most prominently in the central bar, represents starlight from older stars. The chaotic, bright regions outside this bar are filled with hot, massive stars buried in thick blankets of dust. The red color around these bright regions is from dust heated by stars, while the red dots scattered throughout the picture are either dusty, old stars or more distant galaxies. The greenish clouds contain cooler interstellar gas and molecular-sized dust grains illuminated by ambient starlight. Astronomers say this image allows them to quantify the process by which space dust -- the same stuff that makes up planets and even people -- is recycled in a galaxy. The picture shows dust at its three main cosmic hangouts: around the young stars, where it is being consumed (red-tinted, bright clouds); scattered about in the space between stars (greenish clouds); and in expelled shells of material from old stars (randomly-spaced red dots). The Large Magellanic Cloud, located 160,000 light-years from Earth, is one of a handful of dwarf galaxies that orbit our own Milky Way. It is approximately one-third as wide as the Milky Way, and, if it could be seen in its entirety, would cover the same amount of sky as a grid of about 480 full moons. About one-third of the entire galaxy can be seen in the Spitzer image. This picture is a composite of infrared light captured by Spitzer. Light with wavelengths of 3.6 (blue) and 8 (green) microns was captured by the telescope's infrared array camera; 24-micron light (red) was detected by the multiband imaging photometer. http://photojournal.jpl.nasa.gov/catalog/PIA07137

Results From Mars Show Electrostatic Charging of the Mars Pathfinder Sojourner Rover

NASA Technical Reports Server (NTRS)

Kolecki, Joseph C.; Siebert, Mark W.

1998-01-01

Indirect evidence (dust accumulation) has been obtained indicating that the Mars Pathfinder rover, Sojourner, experienced electrostatic charging on Mars. Lander camera images of the Sojourner rover provide distinctive evidence of dust accumulation on rover wheels during traverses, turns, and crabbing maneuvers. The sol 22 (22nd Martian "day" after Pathfinder landed) end-of-day image clearly shows fine red dust concentrated around the wheel edges with additional accumulation in the wheel hubs. A sol 41 image of the rover near the rock "Wedge" (see the next image) shows a more uniform coating of dust on the wheel drive surfaces with accumulation in the hubs similar to that in the previous image. In the sol 41 image, note particularly the loss of black-white contrast on the Wheel Abrasion Experiment strips (center wheel). This loss of contrast was also seen when dust accumulated on test wheels in the laboratory. We believe that this accumulation occurred because the Martian surface dust consists of clay-sized particles, similar to those detected by Viking, which have become electrically charged. By adhering to the wheels, the charged dust carries a net nonzero charge to the rover, raising its electrical potential relative to its surroundings. Similar charging behavior was routinely observed in an experimental facility at the NASA Lewis Research Center, where a Sojourner wheel was driven in a simulated Martian surface environment. There, as the wheel moved and accumulated dust (see the following image), electrical potentials in excess of 100 V (relative to the chamber ground) were detected by a capacitively coupled electrostatic probe located 4 mm from the wheel surface. The measured wheel capacitance was approximately 80 picofarads (pF), and the calculated charge, 8 x 10(exp -9) coulombs (C). Voltage differences of 100 V and greater are believed sufficient to produce Paschen electrical discharge in the Martian atmosphere. With an accumulated net charge of 8 x 10(exp -9) C, and average arc time of 1 msec, arcs can also occur with estimated arc currents approaching 10 milliamperes (mA). Discharges of this magnitude could interfere with the operation of sensitive electrical or electronic elements and logic circuits. Sojourner rover wheel tested in laboratory before launch to Mars. Before launch, we believed that the dust would become triboelectrically charged as it was moved about and compacted by the rover wheels. In all cases observed in the laboratory, the test wheel charged positively, and the wheel tracks charged negatively. Dust samples removed from the laboratory wheel averaged a few ones to tens of micrometers in size (clay size). Coarser grains were left behind in the wheel track. On Mars, grain size estimates of 2 to 10 mm were derived for the Martian surface materials from the Viking Gas Exchange Experiment. These size estimates approximately match the laboratory samples. Our tentative conclusion for the Sojourner observations is that fine clay-sized particles acquired an electrostatic charge during rover traverses and adhered to the rover wheels, carrying electrical charge to the rover. Since the Sojourner rover carried no instruments to measure this mission's onboard electrical charge, confirmatory measurements from future rover missions on Mars are desirable so that the physical and electrical properties of the Martian surface dust can be characterized. Sojourner was protected by discharge points, and Faraday cages were placed around sensitive electronics. But larger systems than Sojourner are being contemplated for missions to the Martian surface in the foreseeable future. The design of such systems will require a detailed knowledge of how they will interact with their environment. Validated environmental interaction models and guidelines for the Martian surface must be developed so that design engineers can test new ideas prior to cutting hardware. These models and guidelines cannot be validated without actual flighata. Electrical charging of vehicles and, one day, astronauts moving across the Martian surface may have moderate to severe consequences if large potential differences develop. The observations from Sojourner point to just such a possibility. It is desirable to quantify these results. The various lander/rover missions being planned for the upcoming decade provide the means for doing so. They should, therefore, carry instruments that will not only measure vehicle charging but characterize all the natural and induced electrical phenomena occurring in the environment and assess their impact on future missions.

Ground truth of (sub-)micrometre cometary dust - Results of MIDAS onboard Rosetta

NASA Astrophysics Data System (ADS)

Mannel, Thurid; Bentley, Mark; Schmied, Roland; Torkar, Klaus; Jeszenszky, Harald; Romsted, Jens; Levasseur-Regourd, A.; Weber, Iris; Jessberger, Elmar K.; Ehrenfreund, Pascale; Köberl, Christian; Havnes, Ove

2016-10-01

The investigation of comet 67P by Rosetta has allowed the comprehensive characterisation of pristine cometary dust particles ejected from the nucleus. Flying alongside the comet at distances as small as a few kilometres, and with a relative velocity of only centimetres per second, the Rosetta payload sampled almost unaltered dust. A key instrument to study this dust was MIDAS (the Micro-Imaging Dust Analysis System), a dedicated atomic force microscope that scanned the surfaces of hundreds of (sub-)micrometre sized particles in 3D with resolutions down to nanometres. This offers the unique opportunity to explore the morphology of smallest cometary dust and expand our current knowledge about cometary material.Here we give an overview of dust collected and analysed by MIDAS and highlight its most important features. These include the ubiquitous agglomerate nature of the dust, which is found at all size scales from the largest (>10 µm) through to the smallest (<1 µm) dust particles. The sub-units show characteristic sizes and shapes that are compared with model predictions for interstellar dust.Our findings constrain key parameters of the evolution of the early Solar System. We will discuss which dust growth model is favoured by the observed morphology and how the results restrict cometary formation. Finally, dust particles detected by MIDAS resemble primitive interplanetary dust which is a strong argument for a common cometary origin.

Dust Devil Tracks and Wind Streaks in the North Polar Region of Mars: A Study of the 2007 Phoenix Mars Lander Sites

NASA Technical Reports Server (NTRS)

Drake, Nathan B.; Tamppari, Leslie K.; Baker, R. David; Cantor, Bruce A.; Hale, Amy S.

2006-01-01

The 65-72 latitude band of the North Polar Region of Mars, where the 2007 Phoenix Mars Lander will land, was studied using satellite images from the Mars Global Surveyor (MGS) Mars Orbiter Camera Narrow-Angle (MOC-NA) camera. Dust devil tracks (DDT) and wind streaks (WS) were observed and recorded as surface evidence for winds. No active dust devils (DDs) were observed. 162 MOC-NA images, 10.3% of total images, contained DDT/WS. Phoenix landing Region C (295-315W) had the highest concentration of images containing DDT/WS per number of available images (20.9%); Region D (130-150W) had the lowest (3.5%). DDT and WS direction were recorded for Phoenix landing regions A (110-130W), B (240-260W), and C to infer local wind direction. Region A showed dominant northwest-southeast DDT/WS, Region B showed dominant north-south, east-west and northeast-southwest DDT/WS, and region C showed dominant west/northwest - east/southeast DDT/ WS. Results indicate the 2007 Phoenix Lander has the highest probability of landing near DDT/WS in landing Region C. Based on DDT/WS linearity, we infer Phoenix would likely encounter directionally consistent background wind in any of the three regions.

First images of a possible CO(+)-tail of comet P/Schwassmann-Wachmann 1 observed against the dust coma background

NASA Technical Reports Server (NTRS)

Jockers, Klaus; Bonev, T.; Ivanova, Violeta; Rauer, H.

1992-01-01

Comet P/Schwassmann-Wachmann 1 was observed with the 2m-Ritchey-Cretien Telescope of the Bulgarian National Observatory, Rozhen, Bulgaria, using the CCD-camera and focal reducer of the Max-Planck-Institute for Aeronomy. Images were taken in a red continuum window and in the 2-0 A(exp 2)Pi - X(exp 2)Sigma(+) band of CO(+) located in the blue part of the spectrum. The red images reveal an extended dust coma. From a comparison of the red and blue images a dust reddening of 13.2 percent per 1000 A is derived. At 642 nm the magnitude of the comet with a square diaphragm of 4.5 arcsec is 16.6. The blue images, taken in the CO(+) band, show a significantly different brightness distribution which is interpreted as presence of a CO(+) coma and tail superimposed on the continuum. A column density of several 10(exp 10) CO(+) molecules cm(exp -2) is derived. The tail thickness of 10(exp 5) km is unexpectedly small. We estimate the CO(+) production rate to about 6 x 10(exp 26) CO(+) particles s(exp -1). This value does not support the idea that the outbursts of this comet are caused by crystallization of amorphous water ice.

Revealing the structure and dust content of debris disks on solar systems scales with GPI

NASA Astrophysics Data System (ADS)

Duchene, Gaspard; Fitzgerald, Michael P.; Kalas, Paul; Graham, James R.; Arriaga, Pauline; Bruzzone, Sebastian; Chen, Christine; Dawson, Rebekah Ilene; Dong, Ruobing; Draper, Zachary; Esposito, Thomas; Follette, Katherine; Hung, Li-Wei; Lawler, Samantha; Metchev, Stanimir; Millar-Blanchaer, Max; Murray-Clay, Ruth; Perrin, Marshall D.; Rameau, Julien; Wang, Jason; Wolff, Schuyler; Macintosh, Bruce; GPIES Team

2016-01-01

High contrast scattered light images offer the best prospect to assess the detailed geometry and structure of dusty debris disks. In turn, such images can yield profound insight on the architecture of the underlying planetary system as dust grains respond to the gravitational pull of planetary bodies. A new generation of extreme adaptive optics systems now enables an unprecedented exploration of circumstellar disks on solar system scales. Here we review the new science derived from over a dozen debris disks imaged with the Gemini Planet Imager (GPI) as part of the GPI Exoplanet Survey (GPIES). In addition to its exquisite imaging capability, GPI's polarimetric mode provides invaluable insight on the dust content of each disk, in most cases for the very first time. These early results typically reveal narrow belts of material with evacuated regions roughly 50-100 AU in radius, subtle asymmetries in structure and high degree of linear polarization. We will provide an overview of the disk observations made during the GPIES campaign to date and will discuss in more detail some of the most remarkable systems.This work is supported by grants NSF AST-0909188, -1411868, -1413718; NASA NNX-15AD95G, -14AJ80G, -11AD21G; and the NExSS research network.

Dust deposition and removal at the MER landing sites from observations of the Panoramic Camera (Pancam) calibration targets

NASA Astrophysics Data System (ADS)

Kinch, K. M.; Bell, J. F.; Madsen, M. B.

2012-12-01

The Panoramic Cameras (Pancams) [1] on NASA's Mars Exploration Rovers have each returned in excess of 17000 images of their external calibration targets (caltargets), a set of optically well-characterized patches of materials with differing reflectance properties. During the mission dust deposition on the caltargets changed their optical reflectance properties [2]. The thickness of dust on the caltargets can be derived with high confidence from the contrast between brighter and darker colored patches. The dustier the caltarget the less contrast. We present a new history of dust deposition and removal at the two MER landing sites. Our data reveals two quite distinct dust environments. At the Spirit landing site half the Martian year is dominated by dust deposition, the other half by dust removal that usually happens during brief sharp wind events. At the Opportunity landing site the Martian year has a four-season cycle of deposition-removal-deposition-removal with dust removal happening gradually throughout the two removal seasons. Comparison to atmospheric optical depth measurements [3] shows that dust removals happen during dusty high-wind periods and that dust deposition rates are roughly proportional to the atmospheric dust load. We compare with dust deposition studies from other Mars landers and also present some early results from observation of dust on a similar camera calibration target on the Mars Science Laboratory mission. References: 1. Bell, J.F., III, et al., Mars Exploration Rover Athena Panoramic Camera (Pancam) investigation. J. Geophys. Res., 2003. 108(E12): p. 8063. 2. Kinch, K.M., et al., Dust Deposition on the Mars Exploration Rover Panoramic Camera (Pancam) Calibration Targets. J. Geophys. Res., 2007. 112(E06S03): p. doi:10.1029/2006JE002807. 3. Lemmon, M., et al., Atmospheric Imaging Results from the Mars Exploration Rovers: Spirit and Opportunity. Science, 2004. 306: p. 1753-1756. Deposited dust optical depth on the Pancam caltargets as a function of time. The lower x-axes show sol number, the upper x-axes shows the areocentric longitude of the sun, Ls. Data shown are from caltarget observations with solar incidence angle i < 45°. Left column is Spirit. Right column is Opportunity. Top row shows our derived deposited optical depth in the L5 (535 nm) filter. Bottom row shows the atmospheric optical depth in the L8 (440 nm) filter as reported by the MER atmospheric team [3].

Numerical simulation of "an American haboob"

NASA Astrophysics Data System (ADS)

Vukovic, A.; Vujadinovic, M.; Pejanovic, G.; Andric, J.; Kumjian, M. R.; Djurdjevic, V.; Dacic, M.; Prasad, A. K.; El-Askary, H. M.; Paris, B. C.; Petkovic, S.; Nickovic, S.; Sprigg, W. A.

2014-04-01

A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land-atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High-resolution numerical models are required for accurate simulation of the small scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran Desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME-DREAM (Non-hydrostatic Mesoscale Model on E grid, Janjic et al., 2001; Dust REgional Atmospheric Model, Nickovic et al., 2001; Pérez et al., 2006) with 4 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The scope of this paper is validation of the dust model performance, and not use of the model as a tool to investigate mechanisms related to the storm. Results demonstrate the potential technical capacity and availability of the relevant data to build an operational system for dust storm forecasting as a part of a warning system. Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (~25 km), the model PM10 surface dust concentration reached ~2500 μg m-3, but underestimated the values measured by the PM10 stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health.

Hubble's Wide View of 'Mystic Mountain' in Infrared

NASA Image and Video Library

2010-04-23

NASA image release April 22, 2010 This is a NASA Hubble Space Telescope near-infrared-light image of a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby stars in the tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation Carina. The image marks the 20th anniversary of Hubble's launch and deployment into an orbit around Earth. The image reveals a plethora of stars behind the gaseous veil of the nebula's wall of hydrogen, laced with dust. The foreground pillar becomes semi-transparent because infrared light from background stars penetrates through much of the dust. A few stars inside the pillar also become visible. The false colors are assigned to three different infrared wavelength ranges. Hubble's Wide Field Camera 3 observed the pillar in February and March 2010. Object Names: HH 901, HH 902 Image Type: Astronomical Credit: NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI) To read learn more about this image go to: www.nasa.gov/mission_pages/hubble/science/hubble20th-img.... NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Lizard-Skin Surface Texture

NASA Technical Reports Server (NTRS)

2007-01-01

[figure removed for brevity, see original site] Figure 1

The south polar region of Mars is covered seasonally with translucent carbon dioxide ice. In the spring gas subliming (evaporating) from the underside of the seasonal layer of ice bursts through weak spots, carrying dust from below with it, to form numerous dust fans aligned in the direction of the prevailing wind.

The dust gets trapped in the shallow grooves on the surface, helping to define the small-scale structure of the surface. The surface texture is reminiscent of lizard skin (figure 1).

Observation Geometry Image PSP_003730_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 14-May-2007. The complete image is centered at -85.2 degrees latitude, 181.5 degrees East longitude. The range to the target site was 248.5 km (155.3 miles). At this distance the image scale is 24.9 cm/pixel (with 1 x 1 binning) so objects 75 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 06:04 PM and the scene is illuminated from the west with a solar incidence angle of 69 degrees, thus the sun was about 21 degrees above the horizon. At a solar longitude of 237.5 degrees, the season on Mars is Northern Autumn.

Infrared images of merging galaxies

NASA Technical Reports Server (NTRS)

Wright, G. S.; James, P. A.; Joseph, R. D.; Mclean, I. S.; Doyon, R.

1990-01-01

Infrared imaging of interacting galaxies is especially interesting because their optical appearance is often so chaotic due to extinction by dust and emission from star formation regions, that it is impossible to locate the nuclei or determine the true stellar distribution. However, at near-infrared wavelengths extinction is considerably reduced, and most of the flux from galaxies originates from red giant stars that comprise the dominant stellar component by mass. Thus near infrared images offer the opportunity to study directly components of galactic structure which are otherwise inaccessible. Such images may ultimately provide the framework in which to understand the activity taking place in many of the mergers with high Infrared Astronomy Satellite (IRAS) luminosities. Infrared images have been useful in identifying double structures in the nuclei of interacting galaxies which have not even been hinted at by optical observations. A striking example of this is given by the K images of Arp 220. Graham et al. (1990) have used high resolution imaging to show that it has a double nucleus coincident with the radio sources in the middle of the dust lane. The results suggest that caution should be applied in the identification of optical bright spots as multiple nuclei in the absence of other evidence. They also illustrate the advantages of using infrared imaging to study the underlying structure in merging galaxies. The authors have begun a program to take near infrared images of galaxies which are believed to be mergers of disk galaxies because they have tidal tails and filaments. In many of these the merger is thought to have induced exceptionally luminous infrared emission (cf. Joseph and Wright 1985, Sanders et al. 1988). Although the optical images of the galaxies show spectacular dust lanes and filaments, the K images all have a very smooth distribution of light with an apparently single nucleus.

Use of a Reflective Ultraviolet Imaging System (RUVIS) on Two-Dimensional Dust Impressions Created with Footwear on Multiple Substrates

NASA Astrophysics Data System (ADS)

Engelson, Brian Aaron

Footwear impression evidence in dust is often difficult to locate in ambient light and is a fragile medium that both collection and enhancement techniques can destroy or distort. The collection of footwear impression evidence always begins with non-destructive photographic techniques; however, current methods are limited to oblique lighting of the impression followed by an attempt to photograph in situ. For the vast majority of footwear impressions, an interactive collection method, and thus a potentially destructive procedure, is subsequently carried out to gather the evidence. Therefore, alternative non-destructive means for the preservation and enhancement of footwear impressions in dust merits further attention. Previous research performed with reflected ultraviolet (UV) photography and reflected ultraviolet imaging systems (RUVIS) has shown that there are additional non-destructive methodologies that can be applied to the search for and documentation of footwear impressions in dust. Unfortunately, these prior studies did not include robust comparisons to traditional oblique white light, instead choosing to focus on different UV wavelengths. This study, however, seeks to evaluate the use of a RUVIS device paired with a 254 nanometer (nm) UV light source to locate 2-D footwear impressions in dust on multiple substrates against standard oblique white light techniques and assess the visibility of the impression and amount of background interference present. The optimal angle of incident UV light for each substrate was also investigated. Finally, this study applied an image enhancement technique in order to evaluate its usefulness when looking at the visibility of a footwear impression and the amount of background interference present for enhanced white light and RUVIS pictures of footwear impressions in dust. A collection of eight different substrate types was gathered for investigation, including vinyl composition tile (VCT), ceramic tile, marble tile, magazine paper, steel sheet metal, vinyl flooring, wood flooring, and carpet. Heel impressions were applied to the various substrates utilizing vacuum collected dust and normal walking pressure. Each substrate was then explored and photographed in ambient fluorescent light, oblique white light at 0°, 15°, 30°, and 0° with the light source below the surface plane of the substrate, and 254 nm UV light at 0°, 15°, 30°, 45°, 60°, 75°, 90° and 0° with the light source below the surface plane of the substrate. All pictures were evaluated for clarity and visible detail of the footwear impression and the amount of background interference present, selecting for the best images within a lighting condition group. Additional intra- and intergroup comparisons were carried out to explore differences created by the various lighting conditions. Enhanced images were then created with the best scored pictures and evaluated for additional modifications in impression visibility and background interference. Photographs of footwear impressions in dust illuminated with ambient fluorescent light proved to be the most difficult conditions under which a footwear impression could be visualized. However, both oblique white light and 254 nm UV light lighting conditions showed improvements in either visualization or background dropout, or both, over ambient light conditions. An assessment of the white light and 254 nm UV light RUVIS images also demonstrated that the best angles for the light source for all substrates were oblique 0 and oblique 0° below the surface plane of the substrate lighting. It was found that white light photographs generally provided higher visibility ratings, while RUVIS 254 nm UV light photographs provided better grades for reducing background interference. Enhanced images of white light conditions provided generally poorer quality and quantity of details, while enhanced RUVIS images seemed to improve upon these areas. The use of a RUVIS to capture photographs of footwear impression evidence in dust was found to be a successful secondary non-destructive technique that can be paired with traditional oblique white light procedures. Additionally, the use of below the surface plane of the substrate lighting techniques were found to improve either visibility or background dropout, or both, over standard 0 oblique lighting, depending on the light source, and should be employed, when applicable. Finally, further investigation into digital photo-editing enhancement techniques for footwear impression evidence in dust is needed.

Martian Clouds

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site]

Released 28 June 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image was acquired during early spring near the North Pole. The linear 'ripples' are transparent water-ice clouds. This linear form is typical for polar clouds. The black regions on the margins of this image are areas of saturation caused by the build up of scattered light from the bright polar material during the long image exposure.

Image information: VIS instrument. Latitude 68.1, Longitude 147.9 East (212.1 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Searching for Cool Dust in the Mid-to-far Infrared: The Mass-loss Histories of the Hypergiants μ Cep, VY CMa, IRC+10420, and ρ Cas

NASA Astrophysics Data System (ADS)

Shenoy, Dinesh; Humphreys, Roberta M.; Jones, Terry J.; Marengo, Massimo; Gehrz, Robert D.; Helton, L. Andrew; Hoffmann, William F.; Skemer, Andrew J.; Hinz, Philip M.

2016-03-01

We present mid- and far-IR imaging of four famous hypergiant stars: the red supergiants μ Cep and VY CMa, and the warm hypergiants IRC +10420 and ρ Cas. Our 11-37 μm SOFIA/FORCAST imaging probes cool dust not detected in visual and near-IR imaging studies. Adaptive optics 8-12 μm imaging of μ Cep and IRC +10420 with MMT/MIRAC reveals extended envelopes that are the likely sources of these stars’ strong silicate emission features. We find μ Cep’s mass-loss rate to have declined by about a factor of five over a 13,000 year history, ranging from 5 × 10-6 down to ˜1× 10-6 M⊙ yr-1. The morphology of VY CMa indicates a cooler dust component coincident with the highly asymmetric reflection nebulae seen in the visual and near-IR. The lack of cold dust at greater distances around VY CMa indicates that its mass-loss history is limited to the last ˜1200 years, with an average rate of 6 × 10-4 M⊙ yr-1. We find two distinct periods in the mass-loss history of IRC +10420 with a high rate of 2 × 10-3 M⊙ yr-1 until approximately 2000 years ago, followed by an order of magnitude decrease in the recent past. We interpret this change as evidence of its evolution beyond the RSG stage. Our new infrared photometry of ρ Cas is consistent with emission from the expanding dust shell ejected in its 1946 eruption, with no evidence of newer dust formation from its more recent events. Based on observations obtained with: (1) the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart; and (2) the MMT Observatory on Mt. Hopkins, AZ, a joint facility of the Smithsonian Institution and the University of Arizona.

The deep space 1 encounter with comet 19P/Borrelly

USGS Publications Warehouse

Boice, D.C.; Soderblom, L.A.; Britt, D.T.; Brown, R.H.; Sandel, B.R.; Yelle, R.V.; Buratti, B.J.; Hicks, M.D.; Nelson, R.M.; Rayman, M.D.; Oberst, J.; Thomas, N.

2002-01-01

NASA's Deep Space 1 (DS1) spacecraft successfully encountered comet 19P/Borrelly near perihelion and the Miniature Integrated Camera and Spectrometer (MICAS) imaging system onboard DS1 returned the first high-resolution images of a Jupiter-family comet nucleus and surrounding environment. The images span solar phase angles from 88?? to 52??, providing stereoscopic coverage of the dust coma and nucleus. Numerous surface features are revealed on the 8-km long nucleus in the highest resolution images (47-58 m/pixel). A smooth, broad basin containing brighter regions and mesa-like structures is present in the central part of the nucleus that seems to be the source of jet-like dust features seen in the coma. High ridges seen along the jagged terminator lead to rugged terrain on both ends of the nucleus containing dark patches and smaller series of parallel grooves. No evidence of impact craters with diameters larger than about 200-m are present, indicating a young and active surface. The nucleus is very dark with albedo variations from 0.007 to 0.035. Short-wavelength, infrared spectra from 1.3 to 2.6 ??m revealed a hot, dry surface consistent with less than about 10% actively sublimating. Two types of dust features are seen: Broad fans and highly collimated "jets" in the sunward hemisphere that can be traced to the surface. The source region of the main jet feature, which resolved into at least three smaller "jets" near the surface, is consistent with an area around the rotation pole that is constantly illuminated by the sun during the encounter. Within a few nuclear radii, entrained dust is rapidly accelerated and fragmented and geometrical effects caused from extended source regions are present, as evidenced in radial intensity profiles centered on the jet features that show an increase in source strength with increasing cometocentric distance. Asymmetries in the dust from dayside to nightside are pronounced and may show evidence of lateral flow transporting dust to structures observed in the nightside coma. A summary of the initial results of the Deep Space 1 Mission is provided, highlighting the new knowledge that has been gained thus far.

Transpacific Transport of Dust to North American High-Elevation Sites: Integrated Dataset and Model Outputs

NASA Astrophysics Data System (ADS)

Kassianov, E.; Pekour, M. S.; Flynn, C. J.; Berg, L. K.; Beranek, J.; Zelenyuk, A.; Zhao, C.; Leung, L. R.; Ma, P. L.; Riihimaki, L.; Fast, J. D.; Barnard, J.; Hallar, G. G.; McCubbin, I.; Eloranta, E. W.; McComiskey, A. C.; Rasch, P. J.

2017-12-01

Understanding the effects of dust on the regional and global climate requires detailed information on particle size distributions and their changes with distance from the source. Awareness is now growing about the tendency of the dust coarse mode with moderate ( 3.5 µm) volume median diameter (VMD) to be rather insensitive to complex removal processes associated with long-range transport of dust from the main sources. Our study, with a focus on the transpacific transport of dust, demonstrates that the impact of coarse mode aerosol (VMD 3µm) is well defined at the high-elevation mountain-top Storm Peak Laboratory (SPL, about 3.2 km MSL) and nearby Atmospheric Radiation Measurement (ARM) Climate Research Facility Mobile Facility (AMF) during March 2011. Significant amounts of coarse mode aerosol are also found at the nearest Aerosol Robotic Network (AERONET) site. Outputs from the high-resolution Weather Research and Forecasting (WRF) Model coupled with chemistry (WRF-Chem) show that the major dust event is likely associated with transpacific transport of Asian and African plumes. Satellite data, including the Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging SpectroRadiometer (MISR) aerosol optical depth (AOD) and plume height from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar data provide the observational support of the WRF-Chem simulations. Our study complements previous findings by indicating that the quasi-static nature of the coarse mode appears to be a reasonable approximation for Asian and African dust despite expected frequent orographic precipitation over mountainous regions in the western United States.

Properties and evolution of dust in the interstellar medium.

NASA Astrophysics Data System (ADS)

Flagey, N.

2007-10-01

My thesis is dedicated to the properties and evolution of the dust in the Galactic interstellar medium (ISM), particularly the small sizes end of the dust size distribution. Throughout these three years, new infrared (IR) observations provided by the Spitzer Space Telescope helped me to bring my own contribution to the knowledge of the dust lifecycle. In order to get a view as global as possible, I have studied three different interstellar environments : the diffuse Galactic medium, a molecular cloud and a star forming region. I analyzed one line of sight that points towards the diffuse Galactic ISM, away from bright star forming regions. Combining spectroscopic and photometric data, I have built a mean Galactic near to mid IR spectrum of the dust, that I have afterwards used as a reference. The Polycyclic Aromatic Hydrocarbons (PAHs) bands are present on top of a continuum. In order to interpret the band intensity ratios in terms of PAHs size and ionization state, I have updated our dust model so that it takes into account the size dependent ionization state of the PAHs. The diffuse ISM spectrum is fit for a PAH mean size of about 60 carbon atoms and a cation fraction of about 40%. Molecular size and charged PAHs are thus present within the diffuse medium. A 3-5 μm continuum, first detected in reflection nebulae, is observed to be present in the diffuse ISM emission. This continuum accounts for 70% of the emission in the Spitzer/IRAC 3.6μm filter. Its origin is still unknown. I show that it is neither scattered light nor PAH fluorescence, as this process would require a photon conversion efficiency above 100%. I used Spitzer observations to quantify spatial variations of PAHs properties across the galaxy and on small scales within the Taurus molecular cloud. Analysis of a set of Galactic diffuse ISM sight lines show that the PAHs mean size exhibits significant dispersion, from 40 to 80 carbon atoms, while their ionization fraction stays constant within error bars. I have also analyzed mid and far-IR Spitzer images of the Taurus Molecular Cloud. Each dust component (PAHs, VSGs for Very Small Grains and BGs for Big Grains) can be related to one Spitzer channel (IRAC 8, MIPS 24 and MIPS 160 microns). A first difficulty was to obtain images of the low brightness diffuse emission across the entire cloud. I worked with Spitzer Science Center (SSC) experts to produce the IRAC 8 and MIPS 24 images. For the MIPS 160 I used an inversion algorithm developed to destripe the data. I validated the photometry of each image. The observations show that PAHs are present within a surface layer thinn! er than that penetrated by ultraviolet photons and that of VSGs emission. Such variations cannot be only explained by the extinction and must thus trace real PAH depletion within dense gas where the smallest dust particles may stick on large grains and/or coagulate. During my PhD thesis, I applied for a SSC Visiting Graduate Student grant in order to study the Eagle Nebula (M16), the object that made me decide to do astrophysics, more than ten years ago, when the Hubble Space Telescope imaged the iconic Pillars of Creation. My application was accepted and I spent 6 months within the MIPSGAL Science Team. My aim was to combine IRAC and MIPS data of M16 in order to analyze the properties of the dust within the dusty and gaseous structures, while being involved in the data processing enhancement. The MIPS 24 microns image defines a shell-like structure within the nebula while the pillars are observed at other wavelengths. M16 is a massive star forming region where the dust emission is expected to be powered by the massive stars radiation. However, we show that the UV field is one order of magnitude too small to account for the shell dust temperature. For comparison we analyzed several other Galactic shells. The M16 nebula stands out for having unusually high far-IR color temperature.We considered an alternative interpretation where the dust is heated by gas grain collisions. This interpretation would imply that the shell is a supernova remnant (SNR) about 3000 years old. If confirmed, the Eagle SNR would be the first one detected through dust emission and within a stellar cradle. Moreover, it would illustrate the importance of dust infrared emission within energetics of SNRs. At last, but not at least, the question of the formation and/or destruction of the iconic Pillars of Creation would be (re)opened.

Protective Clothing as a Factor in the Dust Hazard of Potters

PubMed Central

Bloor, W. A.; Dinsdale, A.

1962-01-01

Investigations into the factors affecting dust concentrations in the breathing zone of pottery operatives have shown that cotton overalls constitute a serious source of dust. Attempts to overcome this difficulty by treatment of the material were not successful, so other types of materials were investigated. Terylene was found to have outstandingly desirable properties; types of “terylene” material and designs of clothing were defined. Factory tests showed that with this new protective clothing reductions of up to 65% in breathing zone dust concentrations were achieved. This type of clothing is now being officially recommended by the Joint Standing Committee for the Pottery Industry. Images PMID:13971816

Spirit Feels Dust Gust

NASA Technical Reports Server (NTRS)

2007-01-01

On sol 1149 (March 28, 2007) of its mission, NASA's Mars Exploration Rover Spirit caught a wind gust with its navigation camera. A series of navigation camera images were strung together to create this movie. The front of the gust is observable because it was strong enough to lift up dust. From assessing the trajectory of this gust, the atmospheric science team concludes that it is possible that it passed over the rover. There was, however, no noticeable increase in power associated with this gust. In the past, dust devils and gusts have wiped the solar panels of dust, making it easier for the solar panels to absorb sunlight.

ALMA REVEALS THE ANATOMY OF THE mm-SIZED DUST AND MOLECULAR GAS IN THE HD 97048 DISK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walsh, Catherine; Maud, Luke T.; Juhász, Attila

Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ∼ mm wavelengths. We present the first spatially resolved ∼ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°–40°. HD 97048more » is another source for which the large (∼ mm-sized) dust grains are more centrally concentrated than the small (∼ μ m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10–20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.« less

ALMA Reveals the Anatomy of the mm-sized Dust and Molecular Gas in the HD 97048 Disk

NASA Astrophysics Data System (ADS)

Walsh, Catherine; Juhász, Attila; Meeus, Gwendolyn; Dent, William R. F.; Maud, Luke T.; Aikawa, Yuri; Millar, Tom J.; Nomura, Hideko

2016-11-01

Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ˜ mm wavelengths. We present the first spatially resolved ˜ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°-40°. HD 97048 is another source for which the large (˜ mm-sized) dust grains are more centrally concentrated than the small (˜μm-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10-20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

Dune and Dust Devil Tracks

NASA Technical Reports Server (NTRS)

2004-01-01

31 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark sand dune patch that occurs on the floor of a southern hemisphere crater near 64.1oS, 197.2oW. Passing dust devils have disrupted the fine, bright dust that coats the surrounding terrain, leaving wildly-varied streak patterns. Dark dots to the left (west) of the dune are boulders. The picture covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.

Dust mass distribution around comet 67P/Churyumov-Gerasimenko determined via parallax measurements using Rosetta's OSIRIS cameras

NASA Astrophysics Data System (ADS)

Ott, T.; Drolshagen, E.; Koschny, D.; Güttler, C.; Tubiana, C.; Frattin, E.; Agarwal, J.; Sierks, H.; Bertini, I.; Barbieri, C.; Lamy, P. I.; Rodrigo, R.; Rickman, H.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Boudreault, S.; Cremonese, G.; Da Deppo, V.; Davidsson, B.; Debei, S.; De Cecco, M.; Deller, J.; Feller, C.; Fornasier, S.; Fulle, M.; Geiger, B.; Gicquel, A.; Groussin, O.; Gutiérrez, P. J.; Hofmann, M.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Keller, H. U.; Knollenberg, J.; Kovacs, G.; Kramm, J. R.; Kührt, E.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Lin, Z.-Y.; López-Moreno, J. J.; Marzari, F.; Mottola, S.; Naletto, G.; Oklay, N.; Pajola, M.; Shi, X.; Thomas, N.; Vincent, J.-B.; Poppe, B.

2017-07-01

The OSIRIS (optical, spectroscopic and infrared remote imaging system) instrument on board the ESA Rosetta spacecraft collected data of 67P/Churyumov-Gerasimenko for over 2 yr. OSIRIS consists of two cameras, a Narrow Angle Camera and a Wide Angle Camera. For specific imaging sequences related to the observation of dust aggregates in 67P's coma, the two cameras were operating simultaneously. The two cameras are mounted 0.7 m apart from each other, as a result this baseline yields a parallax shift of the apparent particle trails on the analysed images directly proportional to their distance. Thanks to such shifts, the distance between observed dust aggregates and the spacecraft was determined. This method works for particles closer than 6000 m to the spacecraft and requires very few assumptions. We found over 250 particles in a suitable distance range with sizes of some centimetres, masses in the range of 10-6-102 kg and a mean velocity of about 2.4 m s-1 relative to the nucleus. Furthermore, the spectral slope was analysed showing a decrease in the median spectral slope of the particles with time. The further a particle is from the spacecraft the fainter is its signal. For this reason, this was counterbalanced by a debiasing. Moreover, the dust mass-loss rate of the nucleus could be computed as well as the Afρ of the comet around perihelion. The summed-up dust mass-loss rate for the mass bins 10-4-102 kg is almost 8300 kg s-1.

The structure of cometary dust - first results from the MIDAS Atomic Force Microscope onboard Rosetta

NASA Astrophysics Data System (ADS)

Bentley, M. S.; Torkar, K.; Romstedt, J.

2014-12-01

A decade after launch the European Space Agency's Rosetta spacecraft has finally arrived at comet 67P/Churyumov-Gerasimenko. Unlike previous cometary missions, Rosetta is not a flyby, limited to taking a snapshot of the comet at a single heliocentric distance. Instead, Rosetta intercepted the comet prior to the onset of major activity and will chart its evolution during its perihelion passage and beyond. Such a unique mission requires a unique payload; as well as the more typical remote sensing instruments, Rosetta also carries sensors to sample in situ the gas and dust environment. One of these instruments is MIDAS, an atomic force microscope designed to collect dust and image it in three dimensions with nanometre resolution. Equipped with an array of sharp tips, four of which are magnetised to allow magnetic force microscopy, MIDAS exposes targets to the incident flux after which they are moved to the microscope for analysis. As well as extending coverage of the dust size distribution down to the finest particles, MIDAS has the unique capability to determine the shape of pristine particles - to determine, for example, if they are compact or fluffy, and to look for features which may be diagnostic of their formation environment or evolution. The magnetic mode lets MIDAS probe samples for magnetic material and to map its location if present. Having been operating almost continuously after hibernation imaging empty targets before exposure, the first exposures were performed when Rosetta entered 30 km bound orbits. The first MIDAS images and analyses of collected dust grains are presented here.

High-Contrast NIR Polarization Imaging of MWC480

NASA Technical Reports Server (NTRS)

McElwain, M. W.; Kusakabe, N.; Hashimoto, J.; Kudo, T.; Kandori, R.; Miyama, S.; Morino, J.-I.; Suto, H.; Suzuki, R.; Tamura, M.;

Athena microscopic Imager investigation

USGS Publications Warehouse

Herkenhoff, K. E.; Squyres, S. W.; Bell, J.F.; Maki, J.N.; Arneson, H.M.; Bertelsen, P.; Brown, D.I.; Collins, S.A.; Dingizian, A.; Elliott, S.T.; Goetz, W.; Hagerott, E.C.; Hayes, A.G.; Johnson, M.J.; Kirk, R.L.; McLennan, S.; Morris, R.V.; Scherr, L.M.; Schwochert, M.A.; Shiraishi, L.R.; Smith, G.H.; Soderblom, L.A.; Sohl-Dickstein, J. N.; Wadsworth, M.V.

2003-01-01

The Athena science payload on the Mars Exploration Rovers (MER) includes the Microscopic Imager (MI). The MI is a fixed-focus camera mounted on the end of an extendable instrument arm, the Instrument Deployment Device (IDD). The MI was designed to acquire images at a spatial resolution of 30 microns/pixel over a broad spectral range (400-700 nm). The MI uses the same electronics design as the other MER cameras but has optics that yield a field of view of 31 ?? 31 mm across a 1024 ?? 1024 pixel CCD image. The MI acquires images using only solar or skylight illumination of the target surface. A contact sensor is used to place the MI slightly closer to the target surface than its best focus distance (about 66 mm), allowing concave surfaces to be imaged in good focus. Coarse focusing (???2 mm precision) is achieved by moving the IDD away from a rock target after the contact sensor has been activated. The MI optics are protected from the Martian environment by a retractable dust cover. The dust cover includes a Kapton window that is tinted orange to restrict the spectral bandpass to 500-700 nm, allowing color information to be obtained by taking images with the dust cover open and closed. MI data will be used to place other MER instrument data in context and to aid in petrologic and geologic interpretations of rocks and soils on Mars. Copyright 2003 by the American Geophysical Union.

ALMA REVEALS POTENTIAL LOCALIZED DUST ENRICHMENT FROM MASSIVE STAR CLUSTERS IN II Zw 40

DOE Office of Scientific and Technical Information (OSTI.GOV)

Consiglio, S. Michelle; Turner, Jean L.; Beck, Sara

2016-12-10

We present subarcsecond images of submillimeter CO and continuum emission from a local galaxy forming massive star clusters: the blue compact dwarf galaxy II Zw 40. At ∼0.″4 resolution (20 pc), the CO(3-2), CO(1-0), 3 mm, and 870 μ m continuum maps illustrate star formation on the scales of individual molecular clouds. Dust contributes about one-third of the 870 μ m continuum emission, with free–free accounting for the rest. On these scales, there is not a good correspondence between gas, dust, and free–free emission. Dust continuum is enhanced toward the star-forming region as compared to the CO emission. We suggestmore » that an unexpectedly low and spatially variable gas-to-dust ratio is the result of rapid and localized dust enrichment of clouds by the massive clusters of the starburst.« less

Advances in Dust Detection and Removal for Tokamaks

NASA Astrophysics Data System (ADS)

Campos, A.; Skinner, C. H.; Roquemore, A. L.; Leisure, J. O. V.; Wagner, S.

2008-11-01

Dust diagnostics and removal techniques are vital for the safe operation of next step fusion devices such as ITER. An electrostatic dust detector[1] developed in the laboratory is being applied to NSTX. In the tokamak environment, large particles or fibres can fall on the grid potentially causing a permanent short. We report on the development of a gas puff system that uses helium to clear such particles from the detector. Experiments with varying nozzle designs, backing pressures, puff durations, and exit flow orientations have obtained an optimal configuration that effectively removes particles from a 25 cm^2 area. Dust removal from next step tokamaks will be required to meet regulatory dust limits. A tripolar grid of fine interdigitated traces has been designed that generates an electrostatic travelling wave for conveying dust particles to a ``drain.'' First trials have shown particle motion in optical microscope images. [1] C. H. Skinner et al., J. Nucl. Mater., 376 (2008) 29.

Fast camera imaging of dust in the DIII-D tokamak

NASA Astrophysics Data System (ADS)

Yu, J. H.; Rudakov, D. L.; Pigarov, A. Yu.; Smirnov, R. D.; Brooks, N. H.; Muller, S. H.; West, W. P.

2009-06-01

Naturally occurring and injected dust particles are observed in the DIII-D tokamak in the outer midplane scrape-off-layer (SOL) using a visible fast-framing camera, and the size of dust particles is estimated using the observed particle lifetime and theoretical ablation rate of a carbon sphere. Using this method, the lower limit of detected dust radius is ˜3 μm and particles with inferred radius as large as ˜1 mm are observed. Dust particle 2D velocities range from approximately 10 to 300 m/s with velocities inversely correlated with dust size. Pre-characterized 2-4 μm diameter diamond dust particles are introduced at the lower divertor in an ELMing H-mode discharge using the divertor materials evaluation system (DiMES), and these particles are found to be at the lower size limit of detection using the camera with resolution of ˜0.2 cm 2 per pixel and exposure time of 330 μs.

Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA

NASA Technical Reports Server (NTRS)

Indebetouw, R.; Matsuura, M.; Dwek, E.; Zanardo, G.; Barlow, M. J.; Baes, M.; Bouchet, P.; Burrows, D. N.; Chevalier, R.; Clayton, G. C.;

Isotopic Ratios Measured in the Dust of Comet 67P/Churyumov-Gerasimenko Using Rosetta/COSIMA

NASA Astrophysics Data System (ADS)

Paquette, J. A.; Engrand, C.; Hilchenbach, M.; Fray, N.; Stenzel, O.; Merouane, S.

2017-12-01

The COSIMA instrument aboard the Rosetta orbiter captured dust from the coma of comet 67P/Churyumov-Gerasimenko on metal targets. The dust was then imaged, and some of it was subjected to Time of Flight Secondary Ion Mass Spectrometry, yielding information on the dust composition. Isotopic ratios for species such as oxygen and sulfur have been measured for a number of COSIMA dust particles and these measurements are presented in this talk. Isotopic ratios for several species have been measured for a number of comets, but with the exception of the Stardust results, these have been measurements in the gas phase. The measurements presented here are from the solid phase, most probably from silicate or carbonaceous material. The isotopic ratios measured in the dust are compared to the measurements in the gas, to values measured in the insoluble organic matter of meteorites, and to the values measured in interplanetary dust particles and Antarctic micrometeorites.

I Got Them Dust Bowl Blues: Wind Erosion in the Music of the Southern Great Plains

NASA Astrophysics Data System (ADS)

Lee, J. A.

2017-12-01

This paper deals with the role of wind erosion and blowing dust on the music of the Dust Bowl region, a portion of the southern Great Plains of the United States. A defining characteristic of the region is dust storms, and in the 1930s, severe dust storms created dramatic images that came to symbolize all of the economic, social and environmental hardships suffered by the people during the 1930s. The music of the time, by Woody Guthrie and others, suggested that the region was being destroyed, never to recover. The region was resilient, however, and in recent decades, dust has been depicted in songs either as an adversity to be endured or simply as a normal part of life in the area. It may be that blowing dust has become a defining characteristic of the region because of a somewhat warped sense of pride in living in an often-difficult environment.

Grain dust and the lungs.

PubMed Central

Chan-Yeung, M.; Ashley, M. J.; Grzybowski, S.

1978-01-01

Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler's lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust. Images p1272-a PMID:348288

Dust emission and transport over Iraq associated with the summer Shamal winds

NASA Astrophysics Data System (ADS)

Karam Francis, Diana Bou; Flamant, Cyrille; Chaboureau, Jean-Pierre; Banks, Jamie

2016-04-01

In this study, we investigate the diurnal evolution of the summer Shamal wind (a quasi-permanent low-level northwesterly wind feature) and its role in dust emission and transport over Iraq, using ground-based and space-borne observations together with a numerical simulation performed with the mesoscale model Meso-NH. A 6-year dataset from the synoptic stations over Iraq allows establishing the prominence of the link between strong near surface winds and reduced visibility in the summer. The detailed processes at play during Shamal events are explored on the basis of a Meso-NH simulation for a given, representative case study (25 June-3 July 2010). The Shamal exhibits an out-of-phase relationship between the surface wind and winds in the lower troposphere (typically 500 m above ground level), the maximum surface wind speeds being observed during the day while in altitude the maximum wind speeds are observed at night. The daytime near surface winds, at the origin of dust emission, are associated with the downward transfer of momentum from the nocturnal low-level jet to the surface due to turbulent mixing after solar heating commences each day. For the first time, an estimate of the dust load associated with summer Shamal events over Iraq has been made using aerosol optical depths derived from the Spinning Enhanced Visible and Infrared Imager, the Moderate Resolution Imaging Spectroradiometer, and the simulation. The dust load exhibits a large diurnal variability, with a daily minimum value of 1 Tg around 0600 UTC and a daily peak of 2.5 Tg or more around 1500 UTC, and is driven by the diurnal cycle of the near surface wind speed. The daily dust load peak associated with the summer Shamal over Iraq is in the same order of magnitude as those derived from simulations downstream of the Bodélé depression in Chad, known to be the world's largest dust source. Keywords: Dust, Low Level Jet, Shamal winds, Middle East, dust sources.

Atmospheric Dynamics of Sub-Tropical Dust Storms

NASA Astrophysics Data System (ADS)

Pokharel, Ashok Kumar

Meso-alpha/beta scale observational and meso-beta/gamma scale numerical model analyses were performed to study the atmospheric dynamics responsible for generating Harmattan, Saudi Arabian, and Bodele Depression dust storms. For each dust storm case study, MERRA reanalysis datasets, WRF simulated very high resolution datasets, MODIS/Aqua and Terra images, EUMETSAT images, NAAPS aerosol modelling plots, CALIPSO images, surface observations, and rawinsonde soundings were analyzed. The analysis of each dust storm carried out separately and an in-depth comparison of the events shows some similarities among the three case studies: (1) the presence of a well-organized baroclinic synoptic scale system, (2) small scale dust emission events which occurred prior to the formation of the primary large-scale dust storms, (3) cross mountain flows which produced a strong leeside inversion layer prior to the large scale dust storm, (4) the presence of thermal wind imbalance in the exit region of the mid-tropospheric jet streak in the lee of the mountains shortly after the time of the inversion formation, (5) major dust storm formation was accompanied by large magnitude ageostrophic isallobaric low-level winds as part of the meso-beta scale adjustment process, (6) substantial low-level turbulence kinetic energy (TKE), (7) formation in the lee of nearby mountains, and (8) the emission of the dust occurred initially in narrow meso-beta scale zones parallel to the mountains, and later reached the meso-alpha scale when suspended dust was transported away from the mountains. In addition to this there were additional meso-beta scale and meso-gamma scale adjustment processes resulting in Kelvin waves in the Harmattan and the Bodele Depression cases and the thermally-forced MPS circulation in all of these three cases. The Kelvin wave preceded a cold pool accompanying the air behind the large scale cold front instrumental in the major dust storm. The Kelvin wave organized the major dust storm in a narrow zone parallel to the mountains before it expanded upscale. The thermally-forced meos-gamma scale adjustment processes, which occurred in the canyons/small valleys, resulted in the numerous dust streaks leading to the entry of the dust into the atmosphere due to the presence of significant vertical motion and the TKE generation. This indicates that there were meso-beta to meso-gamma scale adjustment processes at the lower levels after the imbalance within the exit region of the upper level jet streaks and these processes were responsible for causing the large scale dust storms. Most notably, the sub-tropical jet streak caused the dust storm nearer to the equatorial region after its interaction with the thermally perturbed air mass on the lee of the Tibesti Mountains in the Bodele case study, which is different than the two other cases where the polar jet streaks played this same role at higher latitudes. This represents an original finding. Additionally, a climatological analysis of 15 years (1997-2011) of dust events over the NASA Dryden Flight Research Center (DFRC) in the desert of Southern California was performed to evaluate how the extratropical systems influenced the cause of dust storms over this region. This study indicates that dust events were associated with the development of a deep convective boundary layer, turbulent kinetic energy ≥3 J/kg, a lapse rate between dry adiabatic and moist adiabatic, wind speed above the frictional threshold wind speed necessary to ablate dust from the surface (≥7.3m/s), above the surface the presence of a cold trough, and strong cyclonic jet. These processes are similar in many ways to the dynamics in the other subtropical case studies. This also indicated that the annual mean number of dust events, their mean duration, and the unit duration per number of event were positively correlated with each of the visibility ranges, when binned for <11.2km, <8km, <4.8km, <1.6km, and <1km. The percentage of the dust events by season show that most of the dust events occurred in autumn (44.7%), followed by spring (38.3%) and equally in summer and winter with these seasons each accounting for 8.5% of events.

MRO Mars Color Imager (MARCI) Investigation Primary Mission Results

NASA Astrophysics Data System (ADS)

Edgett, K. S.; Cantor, B. A.; Malin, M. C.; Science; Operations Teams, M.

2008-12-01

The Mars Reconnaissance Orbiter (MRO) Mars Color Imager (MARCI) investigation was designed to recover the wide angle camera science objectives of the Mars Climate Orbiter MARCI which was destroyed upon arrival at Mars in 1999 and extend the daily meteorological coverage of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle investigation that was systematically conducted from March 1999 to October 2006. MARCI consists of two wide angle cameras, each with a 180° field of view. The first acquires data in 5 visible wavelength channels (420, 550, 600, 650, 720 nm), the second in 2 UV channels (260, 320 nm). Data have been acquired daily, except during spacecraft upsets, since 24 September 2006. From the MRO 250 to 315 km altitude orbit, inclined 93 degrees, visible wavelength images usually have a pixel scale of about 1 km at nadir and the UV data are at about 8 km per pixel. Data are obtained during every orbit on the day side of the planet from terminator to terminator. These provide a nearly continuous record of meteorological events and changes in surface frost and albedo patterns that span more than 1 martian year and extend the daily global record of such events documented by the MGS MOC. For a few weeks in September and October 2006, both camera systems operated simultaneously, providing views of weather events at about 1400 local time (MOC) and an hour later at about 1500 (MARCI). The continuous meteorological record, now spanning more than 5 Mars years, shows very repeatable weather from year to year with cloud and dust-raising events occurring in the same regions within about 2 weeks of their prior occurrence in previous years. This provides a measure of predictability ideal for assessing future landing sites, orbiter aerobraking plans, and conditions to be encountered by the current landed spacecraft on Mars. However, less predictable are planet-encircling dust events. MOC observed one in 2001, the next was observed by MARCI in 2007. These occurred at different times of year. While popularly known as global dust storms, the nomenclature is misleading, as in each case a storm did not raise dust nor saltate sand on a global basis. Instead, multiple regional storms created a dust haze which obscured much of the martian surface from viewpoints above the lower atmosphere, but in each case the dust opacity was never so high that one could not determine where dust was being raised and where it was not. Within weeks of the end of the 2001 and 2007 global dust events, martian weather returned to its normal, repeatable pattern, with one exception: occasionally thereafter, dust storms were observed in regions where dust-raising had not been seen in the previous years. In these cases, winds capable of raising dust likely occurred at that location every year, but only became visible following a planet-encircling dust event and deposition of dust on a surface that previously did not have sufficient dust to raise. Other MARCI results center on seasonal monitoring of water vapor in the atmosphere, particularly by taking advantage of the anti-correlation between ozone (observable using the UV channels) and water vapor. Owing to their higher spatial resolution than the MOC daily global coverage, details of seasonal polar cap retreat became more apparent, as with these data it is now possible to separate surface frost from ground-hugging fog which forms along the retreating cap edge. MARCI images and meteorological observations are posted weekly on the Internet for public consumption, and the data are archived every 6 months with the NASA Planetary Data System.

Evaluating minerals of environmental concern using spectroscopy

USGS Publications Warehouse

Swayze, G.A.; Clark, R.N.; Higgins, C.T.; Kokaly, R.F.; Livo, K. Eric; Hoefen, T.M.; Ong, C.; Kruse, F.A.

2006-01-01

Imaging spectroscopy has been successfully used to aid researchers in characterizing potential environmental impacts posed by acid-rock drainage, ore-processing dust on mangroves, and asbestos in serpentine mineral deposits and urban dust. Many of these applications synergistically combine field spectroscopy with remote sensing data, thus allowing more-precise data calibration, spectral analysis of the data, and verification of mapping. The increased accuracy makes these environmental evaluation tools efficient because they can be used to focus field work on those areas most critical to the research effort. The use of spectroscopy to evaluate minerals of environmental concern pushes current imaging spectrometer technology to its limits; we present laboratory results that indicate the direction for future designs of imaging spectrometers.

The Center of Gravity, Systemically Understood

DTIC Science & Technology

2013-05-23

manner that gave him the time to pursue and destroy the retreating army. Centuries later, another great captain – Napoléon Bonaparte – employed...Jena-Auerstadt 1806 In 1806, Napoléon Bonaparte became the first operational artist in the history of modern war when he defeated the Prussian... Napoleon , Operational Art, and the Jena Campaign,” in Historical Perspectives of the Operational Art, ed. Michael D. Krause and R. Cody Phillips

Optical Amplification in 45 Deg - cut BaTiO3

DTIC Science & Technology

1989-12-01

Major Steve Rogers for his help, guidaiice. and inspirational teaching ability. Without his interest and support of research iII the electro-optics field...and most of the equipment used for experimentation. The extensive knowledge atid experience he shared with me was as invaluable as his tremendous...members of the DIME lab for sharing their experience, equipment, and engineering knowledge . I would especially like to thanik Bob Cody, Dave

Social Unrest in China

DTIC Science & Technology

2006-05-08

Responses to Rising Social Unrest,” Testimony Presented to the U.S.-China Economic and Security Review Commission, April 14, 2005. 18 Edward Cody, “A...Murray Scott Tanner, “Chinese Government Responses to Rising Social Unrest,” op. cit. involving over 50,000 workers between January-October 2004.17...Guangzhou officials promised to return some land to the farmers.23 Government Responses The PRC government’s efforts to address social unrest have been

Studying Dust Scattering Halos with Galactic X-ray Binaries

NASA Astrophysics Data System (ADS)

Beeler, Doreen; Corrales, Lia; Heinz, Sebastian

2018-01-01

Dust is an important part of the interstellar medium (ISM) and contributes to the formation of stars and planets. Since the advent of modern X-ray telescopes, Galactic X-ray point sources have permitted a closer look at all phases of the ISM. Interstellar metals from oxygen to iron — in both gas and dust form — are responsible for absorption and scattering of X-ray light. Dust scatters the light in a forward direction and creates a diffuse halo image surrounding many bright Galactic X-ray binaries. We use all the bright X-ray point sources available in the Chandra HETG archive to study dust scattering halos from the local ISM. We have described a data analysis pipeline using a combination of the data reduction software CIAO and Python. We compare our results from Chandra HETG and ACIS-I observations of a well studied dust scattering halo around GX 13+1, in order to characterize any systematic errors associated with the HETG data set. We describe how our data products will be used to measure ISM scaling relations for X-ray extinction, dust abundance, and dust-to-metal ratios.

Generation of multiple toroidal dust vortices by a non-monotonic density gradient in a direct current glow discharge plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Manjit, E-mail: manjit@ipr.res.in; Bose, Sayak; Chattopadhyay, P. K.

2015-09-15

Observation of two well-separated dust vortices in an unmagnetized parallel plate DC glow discharge plasma is reported in this paper. A non-monotonic radial density profile, achieved by an especially designed cathode structure using a concentric metallic disk and ring of different radii, is observed to produce double dust tori between cathode and anode. PIV analysis of the still images of the double tori shows oppositely rotating dust structures between the central disk and the ring. Langmuir probe measurements of background plasma shows a non-uniform plasma density profile between the disk and the ring. Location and sense of rotation of themore » dust vortices coincides with the location and direction of the radial gradient in the ion drag force caused by the radial density gradient. The experimentally observed dust vorticity matches well with the calculated one using hydrodynamic formulations with shear in ion drag dominating over the dust charge gradient. These results corroborate that a radial gradient in the ion drag force directed towards cathode is the principal cause of dust rotation.« less

Evaluation of forensic and anthropological potential of D9S1120 in Mestizos and Amerindian populations from Mexico

PubMed Central

Rangel-Villalobos, Héctor; Sánchez-Gutiérrez, Viviana M; Botello-Ruiz, Miriam; Salazar-Flores, Joel; Martínez-Cortés, Gabriela; Muñoz-Valle, José F; Phillips, Christopher

2012-01-01

Aim To carry out a deeper forensic and anthropological evaluation of the short tandem repeat (STR) D9S1120 in five Mestizo populations and eight Amerindian groups from Mexico. Methods We amplified the STR D9S1120 based on primers and conditions described by Phillips et al, followed by capillary electrophoresis in the genetic analyzer ABI Prism 310. Genotypes were analyzed with the GeneMapper ID software. In each population we estimated statistical parameters of forensic importance and Hardy-Weinberg equilibrium. Heterozygosity and FST-values were compared with those previously obtained with nine STRs of the Combined DNA Index System (CODIS-STRs). Results Amerindian and Mestizo populations showed high frequencies of the allele 9 and 16, respectively. Population structure analysis (AMOVA) showed a significant differentiation between Amerindian groups (FST = 2.81%; P < 0.0001), larger than between Mestizos (FST = 0.44%; P = 0.187). D9S1120 showed less genetic diversity but better population differentiation estimates than CODIS-STRs between Amerindian groups and between Amerindians and Mestizos, but not between Mestizo groups. Conclusion This study evaluated the ability of D9S1120 to be used for human identification purposes and demonstrated its anthropological potential to differentiate Mestizos and Amerindian populations. PMID:23100204

Distribution of dust during two dust storms in Iceland

NASA Astrophysics Data System (ADS)

Ösp Magnúsdóttir, Agnes; Dagsson-Waldhauserova, Pavla; Arnalds, Ólafur; Ólafsson, Haraldur

2017-04-01

Particulate matter mass concentrations and size fractions of PM1, PM2.5, PM4, PM10, and PM15 measured in transversal horizontal profile of two dust storms in southwestern Iceland are presented. Images from a camera network were used to estimate the visibility and spatial extent of measured dust events. Numerical simulations were used to calculate the total dust flux from the sources as 180,000 and 280,000 tons for each storm. The mean PM15 concentrations inside of the dust plumes varied from 10 to 1600 ?g?m?3 (PM10 = 7 to 583 ?g?m?3). The mean PM1 concentrations were 97-241 ?g?m?3 with a maximum of 261 ?g?m?3 for the first storm. The PM1/PM2.5 ratios of >0.9 and PM1/PM10 ratios of 0.34-0.63 show that suspension of volcanic materials in Iceland causes air pollution with extremely high PM1 concentrations, similar to polluted urban areas in Europe or Asia. Icelandic volcanic dust consists of a higher proportion of submicron particles compared to crustal dust. Both dust storms occurred in relatively densely inhabited areas of Iceland. First results on size partitioning of Icelandic dust presented here should challenge health authorities to enhance research in relation to dust and shows the need for public dust warning systems.

Stardust Interstellar Preliminary Examination II: Curating the Interstellar Dust Collector, Picokeystones, and Sources of Impact Tracks

NASA Technical Reports Server (NTRS)

Frank, David R.; Westphal, Andrew J.; Zolensky, Michael E.; Gainsforth, Zack; Butterworth, Anna L.; Bastien, Ronald K.; Allen, Carlton; Anderson, David; Bechtel, Hans A.; Sandford, Scott A.

2013-01-01

We discuss the inherent difficulties that arise during "ground truth" characterization of the Stardust interstellar dust collector. The challenge of identifying contemporary interstellar dust impact tracks in aerogel is described within the context of background spacecraft secondaries and possible interplanetary dust particles and beta-meteoroids. In addition, the extraction of microscopic dust embedded in aerogel is technically challenging. Specifically, we provide a detailed description of the sample preparation techniques developed to address the unique goals and restrictions of the Interstellar Preliminary Exam. These sample preparation requirements and the scarcity of candidate interstellar impact tracks exacerbate the difficulties. We also illustrate the role of initial optical imaging with critically important examples, and summarize the overall processing of the collection to date.

Resolving the Mass Production and Surface Structure of the Enceladus Dust Plume

NASA Astrophysics Data System (ADS)

Kempf, Sascha; Southworth, Benjamin; Spitale, Joseph; Srama, Ralf; Schmidt, Jürgen; Postberg, Frank

2017-04-01

There are ongoing arguments with regards to the Enceldaus plume, both on the total mass of ice particles produced by the plume in kg/s, as well as the structure of plume ejection along the tiger stripes. Herein, results from Cassini's Cosmic Dust Analyzer (CDA) and Imaging Science Subsystem (ISS) are used in conjunction with large-scale plume simulations to resolve each of these issues. Additional results are provided on the short-term variability of the plume, and the relation of specifc surface deposition features to emissions along given areas of the tiger stripes. By adjusting their plume model to the dust flux measured by the Cassini dust detector during the close Enceladus flyby in 2005, Schmidt et al. (2008) obtained a total dust production rate in the plumes of about

Catastrophic Disruption of Comet ISON

NASA Technical Reports Server (NTRS)

Keane, Jacqueline V.; Milam, Stefanie N.; Coulson, Iain M.; Kleyna, Jan T.; Sekanina, Zdenek; Kracht, Rainer; Riesen, Timm-Emmanuel; Meech, Karen J.; Charnley, Steven B.

2016-01-01

We report submillimeter 450 and 850 microns dust continuum observations for comet C/2012 S1 (ISON) obtained at heliocentric distances 0.31-0.08 au prior to perihelion on 2013 November 28 (rh?=?0.0125 au). These observations reveal a rapidly varying dust environment in which the dust emission was initially point-like. As ISON approached perihelion, the continuum emission became an elongated dust column spread out over as much as 60? (greater than 10(exp 5) km in the anti-solar direction. Deconvolution of the November 28.04 850 microns image reveals numerous distinct clumps consistent with the catastrophic disruption of comet ISON, producing approximately 5.2?×?10(exp 10) kg of submillimeter-sized dust. Orbital computations suggest that the SCUBA-2 emission peak coincides with the comet's residual nucleus.

GETTING TO THE HEART OF A GALAXY

NASA Technical Reports Server (NTRS)

2002-01-01

This collage of images in visible and infrared light reveals how the barred spiral galaxy NGC 1365 is feeding material into its central region, igniting massive star birth and probably causing its bulge of stars to grow. The material also is fueling a black hole in the galaxy's core. A galaxy's bulge is a central, football-shaped structure composed of stars, gas, and dust. The black-and-white image in the center, taken by a ground-based telescope, displays the entire galaxy. But the telescope's resolution is not powerful enough to reveal the flurry of activity in the galaxy's hub. The blue box in the galaxy's central region outlines the area observed by the NASA Hubble Space Telescope's visible-light camera, the Wide Field and Planetary Camera 2 (WFPC2). The red box pinpoints a narrower view taken by the Hubble telescope's infrared camera, the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). A barred spiral is characterized by a lane of stars, gas, and dust slashing across a galaxy's central region. It has a small bulge that is dominated by a disk of material. The spiral arms begin at both ends of the bar. The bar is funneling material into the hub, which triggers star formation and feeds the bulge. The visible-light picture at upper left is a close-up view of the galaxy's hub. The bright yellow orb is the nucleus. The dark material surrounding the orb is gas and dust that is being funneled into the central region by the bar. The blue regions pinpoint young star clusters. In the infrared image at lower right, the Hubble telescope penetrates the dust seen in the WFPC2 picture to reveal more clusters of young stars. The bright blue dots represent young star clusters; the brightest of the red dots are young star clusters enshrouded in dust and visible only in the infrared image. The fainter red dots are older star clusters. The WFPC2 image is a composite of three filters: near-ultraviolet (3327 Angstroms), visible (5552 Angstroms), and near-infrared (8269 Angstroms). The NICMOS image, taken at a wavelength of 16,000 Angstroms, was combined with the visible and near-infrared wavelengths taken by WFPC2. The WFPC2 image was taken in January 1996; the NICMOS data were taken in April 1998. Credits for the ground-based image: Allan Sandage (The Observatories of the Carnegie Institution of Washington) and John Bedke (Computer Sciences Corporation and the Space Telescope Science Institute) Credits for the WFPC2 image: NASA and John Trauger (Jet Propulsion Laboratory) Credits for the NICMOS image: NASA, ESA, and C. Marcella Carollo (Columbia University)

Stellar Incubators Seen Cooking up Stars

NASA Image and Video Library

2005-01-12

This image composite compares visible-light and infrared views from NASA's Spitzer Space Telescope of the glowing Trifid Nebula, a giant star-forming cloud of gas and dust located 5,400 light-years away in the constellation Sagittarius. Visible-light images of the Trifid taken with NASA's Hubble Space Telescope, Baltimore, Md. (inside left, figure 1) and the National Optical Astronomy Observatory, Tucson, Ariz., (outside left, figure 1) show a murky cloud lined with dark trails of dust. Data of this same region from the Institute for Radioastronomy millimeter telescope in Spain revealed four dense knots, or cores, of dust (outlined by yellow circles), which are "incubators" for embryonic stars. Astronomers thought these cores were not yet ripe for stars, until Spitzer spotted the warmth of rapidly growing massive embryos tucked inside. http://photojournal.jpl.nasa.gov/catalog/PIA07226

Dust and ionized gas in active radio elliptical galaxies

NASA Technical Reports Server (NTRS)

Forbes, D. A.; Sparks, W. B.; Macchetto, F. D.

1990-01-01

The authors present broad and narrow bandwidth imaging of three southern elliptical galaxies which have flat-spectrum active radio cores (NGC 1052, IC 1459 and NGC 6958). All three contain dust and extended low excitation optical line emission, particularly extensive in the case of NGC 1052 which has a large H alpha + (NII) luminosity. Both NGC 1052 and IC 1459 have a spiral morphology in emission-line images. All three display independent strong evidence that a merger or infall event has recently occurred, i.e., extensive and infalling HI gas in NGC 1052, a counter-rotating core in IC 1459 and Malin-Carter shells in NGC 6958. This infall event is the most likely origin for the emission-line gas and dust, and the authors are currently investigating possible excitation mechanisms (Sparks et al. 1990).

Albedo of Carbon Dioxide Ice in Mars' Residual South Polar Cap

NASA Astrophysics Data System (ADS)

James, P. B.; Wolff, M. J.; Bonev, B.

2015-12-01

The albedo of surface CO2 deposits in the Residual South Polar Cap (RSPC) of Mars controls their net condensation / sublimation over a martian year and is therefore a crucial parameter in determining RSPC stability. The albedo used in previous analyses is obtained by dividing I/F, determined from radiometrically calibrated imaging data, by the cosine of the incidence angle. Because of atmospheric aerosols, the albedo calculated from I/F above the atmosphere is not the surface albedo that enters into stability considerations. In order to determine the surface albedo, we interpolate optical depths determined from CRISM EPF measurements to provide estimates of the dust and ice opacities over the RSPC (Wolff et al., 2009) and use these to determine the actual surface albedos from MARCI images using the radiative transport program DISORT (Stamnes et al., 1988). Assuming that dust is the only contributor to atmospheric opacity, the retrieved surface albedos for the longer wavelength MARCI filters in MY 28 and 29 are found to be consistent despite very different dust opacities in the two years (James et al., 2014). However, this model fails to reproduce the short wavelength behavior in early summer and suggests either an additional opacity source or modification of the CRISM dust opacity or the dust phase function. The consequences of these changes will be discussed.

View of a dust storm taken from Atlantis during STS-106

NASA Image and Video Library

2000-09-11

STS106-718-056 (11 September 2000) --- One of the STS-106 crew members on board the Space Shuttle Atlantis used a handheld 70mm camera to photograph this image of Afghanistan dust/front winds in the upper Amu Darya Valley. The strong winds along the northern border of Afghanistan lofted thick, light brown dust into the air (top half of the view). In this desert environment land surfaces are not protected by vegetation from the effect of blowing wind. The central Asian deserts experience the greatest number of dust storm days on the planet each year. The sharp dust front shows that the dust has not traveled far, but has been raised from the surfaces in the view. Dust is entrained in the atmosphere by horizontal winds but also by vertical movements. Here the vertical component is indicated by the fact that the higher points along the dust front are each topped by a small cumulus cloud, which appear as a line of small white puffballs. Cumulus clouds indicate upward motion and here the air which has entrained the dust is lifting the air above to the level of condensation at each point where a small cloud has formed.

Coprates Chasma

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 21 June 2002) The Science This image covers a portion of Coprates Chasma, located near 15.5S, 57.8W, which is part of the Valles Marineris system of canyons that stretch for thousands of kilometers. This image displays clearly the contrast between bedrock, sand, and dust surfaces. The steepest slopes, such as on the canyon walls, appear to be free of the mantle of dust and sand that is nearly ubiquitous elsewhere in the image. Layering is clearly present in the bedrock unit, but it is not clear if that layering is due to sedimentary deposits or volcanic lava flows. Superimposed on the slopes is a mantle of dust in a manner that appears similar to snow covered mountains on Earth. This is because in both situations, fine-grained dry, particulate material is settling on a sloped surface. Collecting in the valleys and, in some cases, climbing up the slopes are several sand sheets. The amount of cover and the apparent thickness of these sands give some indication to the huge volume of material that is collected here. The orientation of the slip faces of the dunes in this image can be used to deduce the prevalent wind patterns in the region. In this case, the prevalent wind direction is towards the east but there are areas where the winds indicate a more complex system, perhaps indicating topographic control of the local winds. The Story The canyon walls of Coprates, the old name for the Persian River Ab-I-Diz, descend clearly at the top of this image, without being obscured by the dust that covers much of this region. Coprates Chasma is part of Valles Marineris, the largest canyon system in the solar system. In addition to the hard bedrock and dust, sand dunes also appear on the floor of the canyon. They almost look as though they've been raked by a Zen gardener, but the eastward-blowing wind is really responsible for their rows. Scientists can tell the direction of the wind by looking at the slip faces of the dunes -- that is, by identifying the steep, downward slope formed from loose, cascading sand. Some areas seem to have been formed by more complex wind patterns that may have emerged due to the topography of the area. This region is, in fact, pretty complex. The sand in this area looks like it is thick and abundant. Not only has it collected in the valleys, it has also built up enough to begin to 'climb up' the slopes. There is also layering in the bedrock, but who knows if this layering is made of deposits of 'dirt' and rock or from lava. Finally, at the bottom of this image, dust-covered slopes appear like snow-covered mountain s on Earth. This similar look occurs because both dust and snow are fine-grained particles and cover the slopes in comparable ways.

Application of Dusty Plasmas for Space

NASA Astrophysics Data System (ADS)

Bhavasar, Hemang; Ahuja, Smariti

In space, dust particles alone are affected by gravity and radiation pressure when near stars and planets. When the dust particles are immersed in plasma, the dust is usually charged either by photo ionization, due to incident UV radiation, secondary electron emission, due to collisions with energetic ions and electrons, or absorption of charged particles, due to collisions with thermal ions and electrons. A 1 micron radius dust particle in a plasma with an electron temperature of a few eV, will have a charge corresponding to a few thousand electron volts, with a resulting charge to mass ratio, Q/m ¡1. They will also be affected by electric and magnetic fields. Since the electrons are magnetized in these regions, electron E B or diamagnetic cross-field drifts may drive instabilities. Dust grains (micron to sub-micron sized solid particles) in plasma and/or radiative environments can be electrically charged by processes such as plasma current collection or photoemission. The effect of charged dust on known electrojet instabil-ities and low frequency dust acoustic and dust drift instabilities. As the plasma affects the dust particles, the dust particles can affect the plasma environment. In Dust Plasma, Plasma is Combination of ions and electrons. Dusty plasmas (also known as complex plasmas) are ordinary plasmas with embedded solid particles consisting of electrons, ions, and neutrals. The particles can be made of either dielectric or conducting materials, and can have any shape. The typical size range is anywhere from 100 nm up to say 100 m. Most often, these small objects or dust particles are electrically charged. Dusty plasmas are ubiquitous in the universe as proto-planetary and solar nebulae, molecular clouds, supernova explosions, interplanetary medium, circumsolar rings, and steroids. Closer to earth, there are the noctilucent clouds, clouds of tiny (charged) ice particles that form in the summer polar mesosphere at an altitude of about 85 km. In processing plasmas, dust particles are actually grown in the discharge from the reactive gases used to form the plasmas. Perhaps the most intriguing aspect of dusty plasmas is that the particles can be directly imaged and their dynamic behavior recorded as digital images. This is accomplished by laser light scattering from the particles. Since the particle mass is relatively high, their dynamical timescales are much longer than that of the ions or electrons. Dusty plasmas has a broad range of applications including interplanetary space dust, comets, planetary rings, dusty surfaces in space, and aerosols in the atmosphere.

INFRARED LUMINOSITIES AND DUST PROPERTIES OF z approx 2 DUST-OBSCURED GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bussmann, R. S.; Dey, Arjun; Jannuzi, B. T.

We present SHARC-II 350 mum imaging of twelve 24 mum bright (F{sub 24m}u{sub m} > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1 mm imaging of a subset of two DOGs. These objects are selected from the Booetes field of the NOAO Deep Wide-Field Survey. Detections of four DOGs at 350 mum imply infrared (IR) luminosities which are consistent to within a factor of 2 of expectations based on a warm-dust spectral energy distribution (SED) scaled to the observed 24 mum flux density. The 350 mum upper limits for the 8 non-detected DOGsmore » are consistent with both Mrk 231 and M82 (warm-dust SEDs), but exclude cold dust (Arp 220) SEDs. The two DOGs targeted at 1 mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T{sub dust} > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of approx3 x 10{sup 8} M{sub sun}. In comparison to other dusty z approx 2 galaxy populations such as submillimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2 x 10{sup 13} L{sub sun} versus 6 x 10{sup 12} L{sub sun} for the other galaxy populations) that are driven by warmer dust temperatures (>35-60 K versus approx30 K) and lower inferred dust masses (3 x 10{sup 8} M{sub sun} versus 3 x 10{sup 9} M{sub sun}). Wide-field Herschel and Submillimeter Common-User Bolometer Array-2 surveys should be able to detect hundreds of these power-law-dominated DOGs. We use the existing Hubble Space Telescope and Spitzer/InfraRed Array Camera data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24 mum bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although much larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z approx 2 involves a submillimeter bright, cold-dust, and star-formation-dominated phase followed by a 24 mum bright, warm-dust and AGN-dominated phase.« less

East Asian dust storm in May 2017: observations, modelling and its influence on Asia-Pacific region

USDA-ARS?s Scientific Manuscript database

A severe dust storm event originated from the Gobi Desert in Central and East Asia during 2-7 May, 2017. Based on moderate resolution imaging spectroradiometer (MODIS) satellite products, hourly environmental monitoring measurements from 367 Chinese cities and more than 2000 East Asian meteorologica...

Black Widow Nebula Hiding in the Dust

NASA Technical Reports Server (NTRS)

2005-01-01

In this Spitzer image, the two opposing bubbles are being formed in opposite directions by the powerful outflows from massive groups of forming stars. The baby stars can be seen as specks of yellow where the two bubbles overlap.

When individual stars form from molecular clouds of gas and dust they produce intense radiation and very strong particle winds. Both the radiation and the stellar winds blow the dust outward from the star creating a cavity or, bubble.

In the case of the Black Widow Nebula, astronomers suspect that a large cloud of gas and dust condensed to create multiple clusters of massive star formation. The combined winds from these groups of large stars probably blew out bubbles into the direction of least resistance, forming a double bubble.

The infrared image was captured by the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) Legacy project. The Spitzer picture is a four-channel false-color composite, showing emission from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red).

Cometary dust at the smallest scale - latest results of the MIDAS Atomic Force Microscope onboard Rosetta

NASA Astrophysics Data System (ADS)

Bentley, Mark; Torkar, Klaus; Jeszenszky, Harald; Romstedt, Jens; Schmied, Roland; Mannel, Thurid

2015-04-01

The MIDAS instrument onboard the Rosetta orbit is a unique combination of a dust collection and handling system and a high resolution Atomic Force Microscope (AFM). By building three-dimensional images of the dust particle topography, MIDAS addresses a range of fundamental questions in Solar System and cometary science. The first few months of dust collection and scanning revealed a deficit of smaller (micron and below) particles but eventually several 10 µm-class grains were discovered. In fact these were unexpectedly large and close to the limit of what is observable with MIDAS. As a result the sharp tip used by the AFM struck the particles from the side, causing particle breakage and distortion. Analyses so far suggest that the collected particles are fluffy aggregates of smaller sub-units, although determination of the size of these sub-units and high resolution re-imaging remains to be done. The latest findings will be presented here, including a description of the particles collected and the implications of these observations for cometary science and the Rosetta mission at comet 67P.

Churned-Up Rocky Debris and Dust (True Color)

NASA Technical Reports Server (NTRS)

2005-01-01

NASA's Mars Exploration Rover Spirit has been analyzing sulfur-rich rocks and surface materials in the 'Columbia Hills' in Gusev Crater on Mars. This image shows rocky debris and dust, which planetary scientists call 'regolith' or 'soil,' that has been churned up by the rover wheels. This 40-centimeter-wide (16-inch-wide) patch of churned-up dirt, nicknamed 'Paso Robles,' contains brighter patches measured to be high in sulfur by Spirit's alpha particle X-ray Spectrometer. Spirit's panoramic camera took this image on martian day, or sol, 400 (Feb. 16, 2005). The image represents the panoramic camera team's best current attempt at generating a true color view of what this scene would look like if viewed by a human on Mars. The image was generated from a combination of six calibrated, left-eye images acquired through filters ranging from 430-nanometer to 750-nanometer wavelengths.

Seasonal evolution of the Martian cryptic region: influence of the atmospheric opacity

NASA Astrophysics Data System (ADS)

Portyankina, G.; Markiewicz, W. J.; Kossacki, K. J.

2005-08-01

Mars Orbiter Camera (MOC) performed repeated observations of chosen areas in polar regions to monitor seasonal and/or annual changes. Images E09-00028 and R08-01730 centered at 82.5°S, 41°E were taken in years 2001 and 2003 respectively. They show the same morphological features, however differ significantly in surface albedo, the image from 2001 shows a lower albedo than the one from 2003. Imaged areas lie inside the cryptic region and show spider patterns. The observed interannual variability may be related to the global dust storm that happened in 2001 and finished around Ls=230°, i.e. just before image E09-00028 was taken. Here we model the seasonal ice sublimation/condensation cycle to show that the evolution of this particular area of the cryptic region was affected by the dust storm during year 2001. The model used for the present work has been described in Kossacki and Markiewicz, (2004). It includes self-consistent treatment of the sublimation and condensation of CO2 and H2O ices, and was used to calculate surface temperatures and thicknesses of CO2 and H2O ice layers for the corresponding conditions of these two years. Our modelling shows that the dust storm lowered surface temperatures, and thus caused later than usual seasonal sublimation of both CO2 and water ices. It also considerably decreased surface albedo and these two important effects almost cancel: the solar flux is reduced during a dust storm but at the same time the dust that precipitates onto the surface reduces the albedo and thus allows a bigger fraction of the solar radiation to be absorbed. The surface temperature stays at about 146K for almost half of the Martian year, both during 2001 and 2003. We also considered impact of the surface roughness: it results in some smoothing of the average temperature rise that is associated with the defrosting of the surface.

Cloud-Ground Interaction

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site]

Released 30 June 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image of the North Polar water-ice clouds shows how surface topography can affect the linear form. Notice that the crater at the bottom of the image is causing a deflection in the linear form.

Image information: VIS instrument. Latitude 68.4, Longitude 100.7 East (259.3 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Dance of the Light Echoes

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site] Click on image for larger poster version

This composite image from NASA's Spitzer Space Telescope shows the remnant of a star that exploded, called Cassiopeia A (center) and its surrounding 'light echoes' -- dances of light through dusty clouds, created when stars blast apart. The light echoes are colored and the surrounding clouds of dust are gray.

In figure 1, dramatic changes are highlighted in phenomena referred to as light echoes (colored areas) around the Cassiopeia A supernova remnant (center). Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died.

A light echo occurs when a star explodes, acting like a cosmic flashbulb. The light from this explosion zips through nearby dust clumps, illuminating and heating them up slightly. This brief period of warming causes them to glow in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light. In figure 1, this apparent motion can be seen here by the shift in colored dust clumps

Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. This remnant is located 11,000 light-years away in the northern constellation Cassiopeia.

This composite consists of six processed images taken over a time span of three years. Dust features that have not changed over time appear gray, while those that have changed are colored blue or orange. Bluer colors represent an earlier time and redder ones, a later time. The progression of the light echo through the dust can be seen here by the shift in colored dust clumps.

This light echo is the largest ever seen, stretching more than 300 light-years away from Cassiopeia A. If viewed from Earth, the entire frame would take up the same amount of space as seven full moons. The supernova remnant is located 11,000 light-years away in the northern constellation Cassiopeia.

The earliest Spitzer image shown here was taken in February 2005, and the latest one in January 2008. The image was processed to emphasize the light echo by enhancing the areas that change, which appear in color, and dimming regions that remain constant, seen in grayscale. Spurious color artifacts such as diffraction spikes around stars were removed by hand.

Dust deposition on the Mars Exploration Rover Panoramic Camera (Pancam) calibration targets

USGS Publications Warehouse

Kinch, K.M.; Sohl-Dickstein, J.; Bell, J.F.; Johnson, J. R.; Goetz, W.; Landis, G.A.

2007-01-01

The Panoramic Camera (Pancam) on the Mars Exploration Rover mission has acquired in excess of 20,000 images of the Pancam calibration targets on the rovers. Analysis of this data set allows estimates of the rate of deposition and removal of aeolian dust on both rovers. During the first 150-170 sols there was gradual dust accumulation on the rovers but no evidence for dust removal. After that time there is ample evidence for both dust removal and dust deposition on both rover decks. We analyze data from early in both rover missions using a diffusive reflectance mixing model. Assuming a dust settling rate proportional to the atmospheric optical depth, we derive spectra of optically thick layers of airfall dust that are consistent with spectra from dusty regions on the Martian surface. Airfall dust reflectance at the Opportunity site appears greater than at the Spirit site, consistent with other observations. We estimate the optical depth of dust deposited on the Spirit calibration target by sol 150 to be 0.44 ?? 0.13. For Opportunity the value was 0.39 ?? 0.12. Assuming 80% pore space, we estimate that the dust layer grew at a rate of one grain diameter per ???100 sols on the Spirit calibration target. On Opportunity the rate was one grain diameter per ???125 sols. These numbers are consistent with dust deposition rates observed by Mars Pathfinder taking into account the lower atmospheric dust optical depth during the Mars Pathfinder mission. Copyright 2007 by the American Geophysical Union.

Characteristics of mineral dust impacting the Persian Gulf

NASA Astrophysics Data System (ADS)

Ahmady-Birgani, Hesam; McQueen, Kenneth G.; Mirnejad, Hassan

2018-02-01

It is generally assumed that severe dust events in western Iran could be responsible for elevated levels of toxic and radioactive elements in the region. Over a period of 5 months, from January 2012 to May 2012, dust particles in the size range PM10 (i.e. <10 μm) were collected at Abadan, a site beside the Persian Gulf. The research aim was to compare chemical compositions of dust and aerosol samples collected during the non-dusty periods and during two severe dust events. Results of ICP-MS analysis of components indicate that during dust events the concentrations of major elements such as Ca, Mg, Al and K increase relative to ambient conditions when Fe and trace elements such as Cu, Cr, Ni, Pb and Zn are in higher proportions. Toxic trace elements that are generally ascribed to human activities, including industrial and urban pollution, are thus proportionately more abundant in the dust under calm conditions than during dust events, when their concentration is diluted by more abundant mineral particles of quartz, calcite and clay. The variability of chemical species during two dust events, noted by tracking the dust plumes in satellite images, was also assessed and the results relate to two different source areas, namely northern Iraq and northwestern Syria.

How Do Martian Dust Devils Vary Throughout the Sol?

NASA Astrophysics Data System (ADS)

Chapman, R.; Lewis, S.; Balme, M. R.; Steele, L.

2016-12-01

Dust devils are vortices of air made visible by entrained dust particles. Dust devils have been observed on Earth and captured in many Mars lander and orbiter images. Martian dust devils may be important to the global climate and are parameterised within Mars Global Circulation Models (MGCMs). We show that the dust devil parameterisation in use within most MGCMs results in an unexpectedly high level of dust devil activity during morning hours. In contrast to expectations, based on the observed behaviour of terrestrial dust devils and the diurnal maximum thermal contrast at the surface, we find that large areas of the modelled Martian surface experience dust devil activity during the morning as well as in the afternoon, and that many locations experience a peak in dust devil activity before mid-sol. Using the UK MGCM, we study the amount of surface dust lifted by dust devils throughout the diurnal cycle as a proxy for the level of dust devil activity occurring. We compare the diurnal variation in dust devil activity with the diurnal variation of the variables included in the dust devil parameterisation. We find that the diurnal variation in dust devil activity is strongly modulated by near-surface wind speeds. Within the range of daylight hours, higher wind speeds tend to produce more dust devil activity, rather than the activity simply being governed by the availability of heat at the planet's surface, which peaks in early afternoon. We compare our results with observations of Martian dust devil timings and obtain a good match with the majority of surface-based surveys. We do not find such a good match with orbital observations, but these data tend to be biased in their temporal coverage. We propose that the generally accepted description of dust devil behaviour on Mars is incomplete, and that theories of dust devil formation may need to be modified specifically for the Martian environment. Further dust devil observations are required to support any such modifications.

Optimization of high-inclination orbits using planetary flybys for a zodiacal light-imaging mission

NASA Astrophysics Data System (ADS)

Soto, Gabriel; Lloyd, James; Savransky, Dmitry; Grogan, Keith; Sinha, Amlan

2017-09-01

The zodiacal light caused by interplanetary dust grains is the second-most luminous source in the solar system. The dust grains coalesce into structures reminiscent of early solar system formation; their composition has been predicted through simulations and some edge-on observations but better data is required to validate them. Scattered light from these dust grains presents challenges to exoplanet imaging missions: resolution of their stellar environment is hindered by exozodiacal emissions and therefore sets the size and scope of these imaging missions. Understanding the composition of this interplanetary dust in our solar system requires an imaging mission from a vantage point above the ecliptic plane. The high surface brightness of the zodiacal light requires only a small aperture with moderate sensitivity; therefore a 3cm camera is enough to meet the science goals of the mission at an orbital height of 0.1AU above the ecliptic. A 6U CubeSat is the target mass for this mission which will be a secondary payload detaching from an existing interplanetary mission. Planetary flybys are utilized to produce most of the plane change Δv deep space corrective maneuvers are implemented to optimize each planetary flyby. We developed an algorithm which determines the minimum Δv required to place the CubeSat on a transfer orbit to a planet's sphere of influence and maximizes the resultant orbital height with respect to the ecliptic plane. The satellite could reach an orbital height of 0.22 AU with an Earth gravity assist in late 2024 by boarding the Europa Clipper mission.

Properties of a Martian local dust storm in Atlantis Chaos from OMEGA/MEX data

NASA Astrophysics Data System (ADS)

Oliva, F.; Geminale, A.; D'Aversa, E.; Altieri, F.; Bellucci, G.; Carrozzo, F. G.; Sindoni, G.; Grassi, D.

2018-01-01

In this study we present the analysis of the dust properties of a local storm imaged in the Atlantis Chaos region on Mars by the OMEGA imaging spectrometer on March 2nd, 2005. We use the radiative transfer model MITRA to study the dust properties at solar wavelengths between 0.5 μm and 2.5 μm and infer the connection between the local storm dynamics and the topography. We retrieve maps of effective grain radius (reff), optical depth at 9.3 μm (τ9.3) and top altitude (ta) of the dust layer. Our results show that large particles (reff = 1.6 μm) are gathered in the centre of the storm (lat = 33.5° S; lon = 183.5° W), where the optical depth is maximum (τ9.3 > 7.0) and the top altitude exceeds 18 km. Outside the storm, we obtain τ9.3<0.2, in agreement with the estimates derived from global climate models (GCM). We speculate that a low thermal inertia region at the western border of Atlantis Chaos is a possible source of the dust storm. Moreover, we find evidence that topography plays a role in confining the local storm in Atlantis Chaos. The vertical wind component from the GCM does not provide any hint for the triggering of dust lifting. On the other hand, the combination of the horizontal and vertical wind profiles suggests that the dust, once lifted, is pushed eastward and then downward and gets confined within the north-east ridge of Atlantis Chaos. From our results, the thickness of the dust layer collapsed on the surface ranges from about 1 μm at the storm boundaries up to more than 100 μm at its centre. We verify that a layer of dust thicker than 1 μm, deposited on the surface, can prevent the detection of mafic absorption features. However, such features are still present in OMEGA data of Atlantis Chaos registered after the storm. Hence, we deduce that, once the storm is over, the dust deposited on an area larger than the one where it has been observed.

Constraining martian atmospheric dust particle size distributions from MER Navcam observations.

NASA Astrophysics Data System (ADS)

Soderblom, J. M.; Smith, M. D.

2017-12-01

Atmospheric dust plays an important role in atmospheric dynamics by absorbing energy and influencing the thermal structure of the atmosphere [1]. The efficiency by which dust absorbs energy depends on its size and single-scattering albedo. Characterizing these properties and their variability is, thus, important in modeling atmospheric circulation. Near-sun observations of the martian sky from Viking Lander, Mars Pathfinder, and MER Pancam images have been used to characterize the atmospheric scattering phase function. The forward-scattering peak the atmospheric phase function is primarily controlled by the size of aerosol particles and is less sensitive to atmospheric opacity or particle shape and single-scattering albedo [2]. These observations, however, have been limited to scattering angles >5°. We use the MER Navcams, which experience little-to-no debilitating internal instrumental scattered light during near-Sun imaging, enabling measurements of the brightness of the martian sky down to very small scattering angles [3], making them more sensitive to aerosol particle size. Additionally, the Navcams band-pass wavelength is similar to the dust effective particle size, further increasing this sensitivity. These data sample a wide range of atmospheric conditions, including variations in the atmospheric dust loading across the entire martian year, as well as more rapid variations during the onset and dissipation of a global-scale dust storm. General circulation models (GCMs) predict a size-dependence for the transport of dust during dust storms that would result in both spatial (on regional-to-global scales) and temporal (days-to-months) variations in the dust size distribution [4]. The absolute calibration of these data, however, is limited. The instrument temperature measurement is limited to a single thermocouple on the Opportunity left Navcam CCD, and observations of the calibration target by Navcam are infrequent. We discuss ways to mitigate these uncertainties and provide improved recovery of dust particle size distributions from these data. [1] Gierasch and Goody, 1972, J. Atmos. Sci., 29, 400-402. [2] Hansen and Travis, 1974, Space Sci. Rev., 16, 527-610. [3] Soderblom et al., 2008; JGR E06S19. [4] Murphy et al., 1993, JGR 98(E2), 3197-3220.

Kiloparsec-scale Dust Disks in High-redshift Luminous Submillimeter Galaxies

NASA Astrophysics Data System (ADS)

Hodge, J. A.; Swinbank, A. M.; Simpson, J. M.; Smail, I.; Walter, F.; Alexander, D. M.; Bertoldi, F.; Biggs, A. D.; Brandt, W. N.; Chapman, S. C.; Chen, C. C.; Coppin, K. E. K.; Cox, P.; Dannerbauer, H.; Edge, A. C.; Greve, T. R.; Ivison, R. J.; Karim, A.; Knudsen, K. K.; Menten, K. M.; Rix, H.-W.; Schinnerer, E.; Wardlow, J. L.; Weiss, A.; van der Werf, P.

2016-12-01

We present high-resolution (0.″16) 870 μm Atacama Large Millimeter/submillimeter Array (ALMA) imaging of 16 luminous ({L}{IR}˜ 4× {10}12 {L}⊙ ) submillimeter galaxies (SMGs) from the ALESS survey of the Extended Chandra Deep Field South. This dust imaging traces the dust-obscured star formation in these z˜ 2.5 galaxies on ˜1.3 kpc scales. The emission has a median effective radius of R e = 0.″24 ± 0.″02, corresponding to a typical physical size of {R}e= 1.8 ± 0.2 kpc. We derive a median Sérsic index of n = 0.9 ± 0.2, implying that the dust emission is remarkably disk-like at the current resolution and sensitivity. We use different weighting schemes with the visibilities to search for clumps on 0.″12 (˜1.0 kpc) scales, but we find no significant evidence for clumping in the majority of cases. Indeed, we demonstrate using simulations that the observed morphologies are generally consistent with smooth exponential disks, suggesting that caution should be exercised when identifying candidate clumps in even moderate signal-to-noise ratio interferometric data. We compare our maps to comparable-resolution Hubble Space Telescope {H}160-band images, finding that the stellar morphologies appear significantly more extended and disturbed, and suggesting that major mergers may be responsible for driving the formation of the compact dust disks we observe. The stark contrast between the obscured and unobscured morphologies may also have implications for SED fitting routines that assume the dust is co-located with the optical/near-IR continuum emission. Finally, we discuss the potential of the current bursts of star formation to transform the observed galaxy sizes and light profiles, showing that the z˜ 0 descendants of these SMGs are expected to have stellar masses, effective radii, and gas surface densities consistent with the most compact massive ({M}* ˜ 1-2 × 1011 {M}⊙ ) early-type galaxies observed locally.

Hubble space telescope imaging of decoupled dust clouds in the ram pressure stripped Virgo spirals NGC 4402 and NGC 4522

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abramson, Anne; Kenney, Jeffrey D. P., E-mail: anne.abramson@yale.edu, E-mail: jeff.kenney@yale.edu

We present the highest-resolution study to date of the interstellar medium (ISM) in galaxies undergoing ram pressure stripping, using Hubble Space Telescope BVI imaging of NGC 4522 and NGC 4402, Virgo Cluster spirals that are well known to be experiencing intracluster medium (ICM) ram pressure. We find that throughout most of both galaxies, the main dust lane has a fairly well-defined edge, with a population of giant molecular cloud (GMC) sized (tens- to hundreds-of-pc scale), isolated, highly extincting dust clouds located up to ∼1.5 kpc radially beyond it. Outside of these dense clouds, the area has little or no diffusemore » dust extinction, indicating that the clouds have decoupled from the lower-density ISM material that has already been stripped. Several of the dust clouds have elongated morphologies that indicate active ram pressure, including two large (kpc scale) filaments in NGC 4402 that are elongated in the projected ICM wind direction. We calculate a lower limit on the H I + H{sub 2} masses of these clouds based on their dust extinctions and find that a correction factor of ∼10 gives cloud masses consistent with those measured in CO for clouds of similar diameters, probably due to the complicating factors of foreground light, cloud substructure, and resolution limitations. Assuming that the clouds' actual masses are consistent with those of GMCs of similar diameters (∼10{sup 4}-10{sup 5} M {sub ☉}), we estimate that only a small fraction (∼1%-10%) of the original H I + H{sub 2} remains in the parts of the disks with decoupled clouds. Based on Hα images, a similar fraction of star formation persists in these regions, 2%-3% of the estimated pre-stripping star formation rate. We find that the decoupled cloud lifetimes may be up to 150-200 Myr.« less

Polarized Light Imaging of the HD 142527 Transition Disk with the Gemini Planet Imager: Dust around the Close-in Companion

NASA Astrophysics Data System (ADS)

Rodigas, Timothy J.; Follette, Katherine B.; Weinberger, Alycia; Close, Laird; Hines, Dean C.

2014-08-01

When giant planets form, they grow by accreting gas and dust. HD 142527 is a young star that offers a scaled-up view of this process. It has a broad, asymmetric ring of gas and dust beyond ~100 AU and a wide inner gap. Within the gap, a low-mass stellar companion orbits the primary star at just ~12 AU, and both the primary and secondary are accreting gas. In an attempt to directly detect the dusty counterpart to this accreted gas, we have observed HD 142527 with the Gemini Planet Imager in polarized light at Y band (0.95-1.14 μm). We clearly detect the companion in total intensity and show that its position and photometry are generally consistent with the expected values. We also detect a point source in polarized light that may be spatially separated by ~ a few AU from the location of the companion in total intensity. This suggests that dust is likely falling onto or orbiting the companion. Given the possible contribution of scattered light from this dust to previously reported photometry of the companion, the current mass limits should be viewed as upper limits only. If the dust near the companion is eventually confirmed to be spatially separated, this system would resemble a scaled-up version of the young planetary system inside the gap of the transition disk around LkCa 15. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministrio da Cincia, Tecnologia e Inovao (Brazil), and Ministerio de Ciencia, Tecnologa e Innovacin Productiva (Argentina).

Long-term Monitoring of Comet 103P/Hartley 2

NASA Astrophysics Data System (ADS)

Lin, Z.-Y.; Lara, L. M.; Ip, W.-H.

2013-07-01

We report the spectrophotometric, photometric, and imaging monitoring results of comet 103P/Hartley 2 obtained at the Lulin (1 m), Calar Alto (2.2 m), and Beijing Astronomical (2.16 m) observatories from 2010 April to December. We found that a dust feature in the sunward direction was detected starting from the end of September until the beginning of December (our last observation from the Lulin and Calar Alto observatories). Two distinct sunward jet features in the processed images were observed on October 11 and after October 29 until November 2. In parallel, the CN images reveal two asymmetrical jet features which are nearly perpendicular to the Sun-nucleus direction, these asymmetrical features imply that the comet was in a nearly side-on view in late October and early November. In addition to the jet features, the average result of the C2-to-CN production rate ratio ranges from 0.7 to 1.5, consistent with 103P/Hartley 2 being of typical cometary chemistry. We found that the rh dependence for the dust production rate, Afρ (5000 km), is -3.75 ± 0.45 before perihelion and -3.44 ± 1.20 during the post-perihelion period. We detected higher dust reddening around the optocenter and decreased reddening along the sunward jet feature. We concluded that higher dust reddening could be associated with strong jet activity while lower dust reddening could be associated with the outburst or might imply changes in the optical properties. The average dust color did not appear to vary significantly as the comet passed through perihelion. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), at Lulin Observatory operated by the Institute of Astronomy, National Central University in Taiwan, and at Xinglong Station inaugurated by the National Astronomical Observatory (BAO), Beijing.

Short-Wavelength Infrared Views of Messier 81

NASA Technical Reports Server (NTRS)

2003-01-01

The magnificent spiral arms of the nearby galaxy Messier 81 are highlighted in this NASA Spitzer Space Telescope image. Located in the northern constellation of Ursa Major (which also includes the Big Dipper), this galaxy is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years from Earth.

Because of its proximity, M81 provides astronomers with an enticing opportunity to study the anatomy of a spiral galaxy in detail. The unprecedented spatial resolution and sensitivity of Spitzer at infrared wavelengths show a clear separation between the several key constituents of the galaxy: the old stars, the interstellar dust heated by star formation activity, and the embedded sites of massive star formation. The infrared images also permit quantitative measurements of the galaxy's overall dust content, as well as the rate at which new stars are being formed.

The infrared image was obtained by Spitzer's infrared array camera. It is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (yellow) and 8.0 microns (red). Winding outward from the bluish-white central bulge of the galaxy, where old stars predominate and there is little dust, the grand spiral arms are dominated by infrared emission from dust. Dust in the galaxy is bathed by ultraviolet and visible light from the surrounding stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles, composed of silicates (which are chemically similar to beach sand) and polycyclic aromatic hydrocarbons, trace the gas distribution in the galaxy. The well-mixed gas (which is best detected at radio wavelengths) and dust provide a reservoir of raw materials for future star formation.

The infrared-bright clumpy knots within the spiral arms denote where massive stars are being born in giant H II (ionized hydrogen) regions. The 8-micron emission traces the regions of active star formation in the galaxy. Studying the locations of these regions with respect to the overall mass distribution and other constituents of the galaxy (e.g., gas) will help identify the conditions and processes needed for star formation. With the Spitzer observations, this information comes to us without complications from absorption by cold dust in the galaxy, which makes interpretation of visible-light features uncertain.

The white stars scattered throughout the field of view are foreground stars within our own Milky Way galaxy.

Segmented Mirror Image Degradation Due to Surface Dust, Alignment and Figure

NASA Technical Reports Server (NTRS)

Schreur, Julian J.

1999-01-01

In 1996 an algorithm was developed to include the effects of surface roughness in the calculation of the point spread function of a telescope mirror. This algorithm has been extended to include the effects of alignment errors and figure errors for the individual elements, and an overall contamination by surface dust. The final algorithm builds an array for a guard-banded pupil function of a mirror that may or may not have a central hole, a central reflecting segment, or an outer ring of segments. The central hole, central reflecting segment, and outer ring may be circular or polygonal, and the outer segments may have trimmed comers. The modeled point spread functions show that x-tilt and y-tilt, or the corresponding R-tilt and theta-tilt for a segment in an outer ring, is readily apparent for maximum wavefront errors of 0.1 lambda. A similar sized piston error is also apparent, but integral wavelength piston errors are not. Severe piston error introduces a focus error of the opposite sign, so piston could be adjusted to compensate for segments with varying focal lengths. Dust affects the image principally by decreasing the Strehl ratio, or peak intensity of the image. For an eight-meter telescope a 25% coverage by dust produced a scattered light intensity of 10(exp -9) of the peak intensity, a level well below detectability.

X-Ray Scattering Echoes and Ghost Halos from the Intergalactic Medium: Relation to the Nature of AGN Variability

NASA Astrophysics Data System (ADS)

Corrales, Lia

2015-05-01

X-ray bright quasars might be used to trace dust in the circumgalactic and intergalactic medium through the phenomenon of X-ray scattering, which is observed around Galactic objects whose light passes through a sufficient column of interstellar gas and dust. Of particular interest is the abundance of gray dust larger than 0.1 μ m, which is difficult to detect at other wavelengths. To calculate X-ray scattering from large grains, one must abandon the traditional Rayleigh-Gans approximation. The Mie solution for the X-ray scattering optical depth of the universe is ∼ 1%. This presents a great difficulty for distinguishing dust scattered photons from the point source image of Chandra, which is currently unsurpassed in imaging resolution. The variable nature of AGNs offers a solution to this problem, as scattered light takes a longer path and thus experiences a time delay with respect to non-scattered light. If an AGN dims significantly (≳ 3 dex) due to a major feedback event, the Chandra point source image will be suppressed relative to the scattering halo, and an X-ray echo or ghost halo may become visible. I estimate the total number of scattering echoes visible by Chandra over the entire sky: {{N}ech}∼ {{10}3}({{ν }fb}/y{{r}-1}), where {{ν }fb} is the characteristic frequency of feedback events capable of dimming an AGN quickly.

Trapping Dust to Form Planets

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-10-01

Growing a planet from a dust grain is hard work! A new study explores how vortices in protoplanetary disks can assist this process.When Dust Growth FailsTop: ALMA image of the protoplanetary disk of V1247 Orionis, with different emission components labeled. Bottom: Synthetic image constructed from the best-fit model. [Kraus et al. 2017]Gradual accretion onto a seed particle seems like a reasonable way to grow a planet from a grain of dust; after all, planetary embryos orbit within dusty protoplanetary disks, which provides them with plenty of fuel to accrete so they can grow. Theres a challenge to this picture, though: the radial drift problem.The radial drift problem acknowledges that, as growing dust grains orbit within the disk, the drag force on them continues to grow as well. For large enough dust grains perhaps around 1 millimeter the drag force will cause the grains orbits to decay, and the particles drift into the star before they are able to grow into planetesimals and planets.A Close-Up Look with ALMASo how do we overcome the radial drift problem in order to form planets? A commonly proposed mechanism is dust trapping, in which long-lived vortices in the disk trap the dust particles, preventing them from falling inwards. This allows the particles to persist for millions of years long enough to grow beyond the radial drift barrier.Observationally, these dust-trapping vortices should have signatures: we would expect to see, at millimeter wavelengths, specific bright, asymmetric structures where the trapping occurs in protoplanetary disks. Such disk structures have been difficult to spot with past instrumentation, but the Atacama Large Millimeter/submillimeter Array (ALMA) has made some new observations of the disk V1247 Orionis that might be just what were looking for.Schematic of the authors model for the disk of V1247 Orionis. [Kraus et al. 2017]Trapped in a Vortex?ALMAs observations of V1247 Orionis are reported by a team of scientists led by Stefan Kraus (University of Exeter) in a recent publication. Kraus and collaborators show that the protoplanetary disk of V1247 Orionis contains a ring-shaped, asymmetric inner disk component, as well as a sharply confined crescent structure. These structures are consistent with the morphologies expected from theoretical models of vortex formation in disks.Kraus and collaborators propose the following picture: an early planet is orbiting at 100 AU within the disk, generating a one-armed spiral arm as material feeds the protoplanet. As the protoplanet orbits, it clears a gap between the ring and the crescent, and it simultaneously triggers two vortices, visible as the crescent and the bright asymmetry in the ring. These vortices are then able to trap millimeter-sized particles.Gas column density of the authors radiation-hydrodynamic simulation of V1247 Orioniss disk. [Kraus et al. 2017]The authors run detailed hydrodynamics simulations of this scenario and compare them (as well as alternative theories) to the ALMA observations of V1247 Orionis. The simulations support their model, producing sample scattered-light images thatmatchwell the one-armed spiral observed in previous scattered-light images of the disk.How can we confirm V1247 Orionis providesan example of dust-trapping vortices? One piece of supporting evidence would be the discovery of the protoplanet that Kraus and collaborators theorize triggered the potential vortices in this disk. Future deeper ALMA imaging may make this possible, helping to confirm our picture of how dust builds into planets.CitationStefan Kraus et al 2017 ApJL 848 L11. doi:10.3847/2041-8213/aa8edc

HUBBLE SNAPS 'FAMILY PORTRAIT'

NASA Technical Reports Server (NTRS)

2002-01-01

The Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has peered into the Cone Nebula, revealing a stunning image of six baby sun-like stars surrounding their mother, a bright, massive star. Known as NGC 2264 IRS, the massive star triggered the creation of these baby stars by releasing high-speed particles of dust and gas during its formative years. The image on the left, taken in visible light by a ground-based telescope, shows the Cone Nebula, located 2,500 light-years away in the constellation Monoceros. The white box pinpoints the location of the star nursery. The nursery cannot be seen in this image because dust and gas obscure it. The large cone of cold molecular hydrogen and dust rising from the lefthand edge of the image was created by the outflow from NGC 2264 IRS. The NICMOS image on the right shows this massive star - the brightest source in the region - and the stars formed by its outflow. The baby stars are only .04 to .08 light-years away from their brilliant mother. The rings surrounding the massive star and the spikes emanating from it are not part of the image. This pattern demonstrates the near-perfect optical performance of NICMOS. A near-perfect optical system should bend light from point-like sources, such as NGC 2264 IRS, forming these diffraction patterns of rings and spikes. This false color image was taken with 1.1-, 1.6-, and 2.2-micron filters. The image was taken on April 28, 1997. Credits: Rodger Thompson, Marcia Rieke and Glenn Schneider (University of Arizona), and NASA Image files in GIF and JPEG format and captions may be accessed on the Internet via anonymous ftp from ftp.stsci.edu in /pubinfo.

Bubbly Little Star

NASA Technical Reports Server (NTRS)

2007-01-01

In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive 'bubbles.' The star is 1,140 light-years away from Earth.

The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution.

This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

HST IMAGING OF DUST STRUCTURES AND STARS IN THE RAM PRESSURE STRIPPED VIRGO SPIRALS NGC 4402 AND NGC 4522: STRIPPED FROM THE OUTSIDE IN WITH DENSE CLOUD DECOUPLING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abramson, A.; Kenney, J.; Crowl, H.

We describe and constrain the origins of interstellar medium (ISM) structures likely created by ongoing intracluster medium (ICM) ram pressure stripping in two Virgo Cluster spirals, NGC 4522 and NGC 4402, using Hubble Space Telescope (HST) BVI images of dust extinction and stars, as well as supplementary H i, H α , and radio continuum images. With a spatial resolution of ∼10 pc in the HST images, this is the highest-resolution study to date of the physical processes that occur during an ICM–ISM ram pressure stripping interaction, ram pressure stripping's effects on the multi-phase, multi-density ISM, and the formation andmore » evolution of ram-pressure-stripped tails. In dust extinction, we view the leading side of NGC 4402 and the trailing side of NGC 4522, and so we see distinct types of features in both. In both galaxies, we identify some regions where dense clouds are decoupling or have decoupled and others where it appears that kiloparsec-sized sections of the ISM are moving coherently. NGC 4522 has experienced stronger, more recent pressure and has the “jellyfish” morphology characteristic of some ram-pressure-stripped galaxies. Its stripped tail extends up from the disk plane in continuous upturns of dust and stars curving up to ∼2 kpc above the disk plane. On the other side of the galaxy, there is a kinematically and morphologically distinct extraplanar arm of young, blue stars and ISM above a mostly stripped portion of the disk, and between it and the disk plane are decoupled dust clouds that have not been completely stripped. The leading side of NGC 4402 contains two kiloparsec-scale linear dust filaments with complex substructure that have partially decoupled from the surrounding ISM. NGC 4402 also contains long dust ridges, suggesting that large parts of the ISM are being pushed out at once. Both galaxies contain long ridges of polarized radio continuum emission indicating the presence of large-scale, ordered magnetic fields. We propose that magnetic fields could bind together gas of different densities, causing nearby gas of different densities to be stripped at the same rate and creating the large, coherent dust ridges and upturns. A number of factors likely play roles in determining what types of structures form as a result of ram pressure, including ram pressure strength and history, the location within the galaxy relative to the leading side, and pre-existing substructure in the ISM that may be bound together by magnetic fields during stripping.« less

Microscopic Comparison of Airfall Dust to Martian Soil

NASA Technical Reports Server (NTRS)

2008-01-01

This pair of images taken by the Optical Microscope on NASA's Phoenix Mars Lander offers a side-by-side comparison of an airfall dust sample collected on a substrate exposed during landing (left) and a soil sample scooped up from the surface of the ground beside the lander. In both cases the sample is collected on a silicone substrate, which provides a sticky surface holding sample particles for observation by the microscope.

Similar fine particles at the resolution limit of the microscope are seen in both samples, indicating that the soil has formed from settling of dust.

The microscope took the image on the left during Phoenix's Sol 9 (June 3, 2008), or the ninth Martian day after landing. It took the image on the right during Sol 17 (June 11, 2008).

The scale bar is 1 millimeter (0.04 inch).

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Imaging Red Supergiants with VLT/SPHERE/ZIMPOL

NASA Astrophysics Data System (ADS)

Cannon, Emily

2018-04-01

In the red supergiant (RSG) phase of evolution massive stars show powerful stellar winds, which strongly influence the supernova (progenitor) properties and control the nature of the compact object that is left behind. Material that is lost in the stellar wind, together with that ejected in the final core collapse, contributes to the chemical enrichment of the local interstellar medium. The mass-loss properties of RSGs are however poorly constrained. Moreover, little is known about the wind driving mechanism. To provide better constraints on both mass-loss rates and physics, high angular resolution observations are needed to unveil the inner regions of the circumstellar environment, where the mass loss is triggered. Using the VLT-SPHERE/ZIMPOL adaptive optics imaging polarimeter, spatially resolved images of four nearby RSGs were obtained in four filters. From these data, we obtain information on geometrical structures in the inner wind, the onset radius and spatial distribution of dust grains, and dust properties such as grain size. As dust grains may play a role in initiating and/or driving the outflow, this could provide us with clues as to the wind driving mechanism.

Do Bare Rocks Exist on the Moon?

NASA Technical Reports Server (NTRS)

Allen, Carlton; Bandfield, Joshua; Greenhagen, Benjamin; Hayne, Paul; Leader, Frank; Paige, David

2017-01-01

Astronaut surface observations and close-up images at the Apollo and Chang'e 1 landing sites confirm that at least some lunar rocks have no discernable dust cover. However, ALSEP (Apollo Lunar Surface Experiments Package) measurements as well as astronaut and LADEE (Lunar Atmosphere and Dust Environment Explorer) orbital observations and laboratory experiments possibly suggest that a fine fraction of dust is levitated and moves across and above the lunar surface. Over millions of years such dust might be expected to coat all exposed rock surfaces. This study uses thermal modeling, combined with Diviner (a Lunar Reconnaissance Orbiter experiment) orbital lunar eclipse temperature data, to further document the existence of bare rocks on the lunar surface.

Analysis of Dust Devils on Mars using CFD

NASA Astrophysics Data System (ADS)

Lange, C. F.; Chen, K.; Davis, J. A.; Gheynani, B. T.

2009-05-01

Recent Mars missions have reported evidence of the existence of dust devils. A detailed study of vortex dynamics will provide a better understanding of this swirling flow of the Martian atmosphere. Further, it is believed that there is a relationship between dust devils and water transport. Recently, the Phoenix Mars mission, designed to investigate ice water and natural events on Mars, has successfully finished. The Phoenix Surface Stereo Imager (SSI) camera captured images of the passage of dust devils over or close to the lander. Additionally, dustless devils, which have similar vortex characteristics but insufficient strength to raise dust from the surface, have been detected in the lander's pressure measurements. It was found that dust devils occur mainly in the early afternoon. Because of this, numerical models of a vortex generator are used to study the physics of this complex swirling flow and the effect of dust devils on the transport of water vapour from the regolith. Characteristic parameters such as core radius and swirl ratio are being explored for scaling factors. Scaling factors will be studied and tested, comparing the small and large scales of numerically generated vortices and laboratory generated vortices. Small scale of numerical models of atmospheric vortices are studied using a commercial software package, ANSYS/CFX11.0 with finite volume method (FVM). Large eddy simulations (LES) of planetary boundary layers are based on NCAR LES code to simulate convective vertical vortices that naturally form in quiescent convective boundary layers (CBL) over homogeneous flat surfaces. This will help to find the approximate location and physical characteristics of the vortices on the surface. The numerical models of atmospheric vortices and the experimental vortex generator validations will help to define the water vapour cycle on Mars.

Pinwheels in the sky, with dust: 3D modelling of the Wolf-Rayet 98a environment

NASA Astrophysics Data System (ADS)

Hendrix, Tom; Keppens, Rony; van Marle, Allard Jan; Camps, Peter; Baes, Maarten; Meliani, Zakaria

2016-08-01

The Wolf-Rayet 98a (WR 98a) system is a prime target for interferometric surveys, since its identification as a `rotating pinwheel nebulae', where infrared images display a spiral dust lane revolving with a 1.4 yr periodicity. WR 98a hosts a WC9+OB star, and the presence of dust is puzzling given the extreme luminosities of Wolf-Rayet stars. We present 3D hydrodynamic models for WR 98a, where dust creation and redistribution are self-consistently incorporated. Our grid-adaptive simulations resolve details in the wind collision region at scales below one percent of the orbital separation (˜4 au), while simulating up to 1300 au. We cover several orbital periods under conditions where the gas component alone behaves adiabatic, or is subject to effective radiative cooling. In the adiabatic case, mixing between stellar winds is effective in a well-defined spiral pattern, where optimal conditions for dust creation are met. When radiative cooling is incorporated, the interaction gets dominated by thermal instabilities along the wind collision region, and dust concentrates in clumps and filaments in a volume-filling fashion, so WR 98a must obey close to adiabatic evolutions to demonstrate the rotating pinwheel structure. We mimic Keck, ALMA or future E-ELT observations and confront photometric long-term monitoring. We predict an asymmetry in the dust distribution between leading and trailing edge of the spiral, show that ALMA and E-ELT would be able to detect fine-structure in the spiral indicative of Kelvin-Helmholtz development, and confirm the variation in photometry due to the orientation. Historic Keck images are reproduced, but their resolution is insufficient to detect the details we predict.

Stellar Snowflake Cluster

NASA Image and Video Library

2005-12-22

Newborn stars, hidden behind thick dust, are revealed in this image of a section of the Christmas Tree cluster from NASA Spitzer Space Telescope, created in joint effort between Spitzer infrared array camera and multiband imaging photometer instrument

Data Compression Algorithm Architecture for Large Depth-of-Field Particle Image Velocimeters

NASA Technical Reports Server (NTRS)

Bos, Brent; Memarsadeghi, Nargess; Kizhner, Semion; Antonille, Scott

2013-01-01

A large depth-of-field particle image velocimeter (PIV) is designed to characterize dynamic dust environments on planetary surfaces. This instrument detects lofted dust particles, and senses the number of particles per unit volume, measuring their sizes, velocities (both speed and direction), and shape factors when the particles are large. To measure these particle characteristics in-flight, the instrument gathers two-dimensional image data at a high frame rate, typically >4,000 Hz, generating large amounts of data for every second of operation, approximately 6 GB/s. To characterize a planetary dust environment that is dynamic, the instrument would have to operate for at least several minutes during an observation period, easily producing more than a terabyte of data per observation. Given current technology, this amount of data would be very difficult to store onboard a spacecraft, and downlink to Earth. Since 2007, innovators have been developing an autonomous image analysis algorithm architecture for the PIV instrument to greatly reduce the amount of data that it has to store and downlink. The algorithm analyzes PIV images and automatically reduces the image information down to only the particle measurement data that is of interest, reducing the amount of data that is handled by more than 10(exp 3). The state of development for this innovation is now fairly mature, with a functional algorithm architecture, along with several key pieces of algorithm logic, that has been proven through field test data acquired with a proof-of-concept PIV instrument.

The Dust-to-Gas Ratio in the Damped Ly alpha Clouds Towards the Gravitationally Lensed QSO 0957+561

NASA Technical Reports Server (NTRS)

Zuo, Lin; Beaver, E. A.; Burbidge, E. Margaret; Cohen, Ross D.; Junkkarinen, Vesa T.; Lyons, R. W.

1997-01-01

We present HST/FOS spectra of the two bright images (A and B) of the gravitationally lensed QSO 0957+561 in the wavelength range 2200-3300 A. We find that the absorption system (Z(sub abs)) = 1.3911) near z(sub em) is a weak, damped Ly alpha system with strong Ly alpha absorption lines seen in both images. However, the H(I) column densities are different, with the line of sight to image A intersecting a larger column density. The continuum shapes of the two spectra differ in the sense that the flux level of image A increases more slowly toward shorter wavelengths than that of image B. We explain this as the result of differential reddening by dust grains in the damped Ly alpha absorber. A direct outcome of this explanation is a determination of the dust-to-gas ratio, k, in the damped Ly alpha system. We derive k = 0.55 + 0.18 for a simple 1/lambda extinction law and k = 0.31 + 0.10 for the Galactic extinction curve. For gravitationally lensed systems with damped Ly alpha absorbers, our method is a powerful tool for determining the values and dispersion of k, and the shapes of extinction curves, especially in the FUV and EUV regions. We compare our results with previous work.

Levels of airborne dust in furniture making factories in the High Wycombe area

PubMed Central

Hounam, R. F.; Williams, J.

1974-01-01

Hounam, R. F. and Williams, J. (1974).British Journal of Industrial Medicine,31, 1-9. Levels of airborne dust in furniture making factories in the High Wycombe area. A dust survey was carried out in five furniture making factories in, or in the vicinity of, High Wycombe. The results, which are among the first to be reported for the United Kingdom, have provided information on the concentrations and size distributions of airborne dust to which wood machinists are currently exposed. Although measured concentrations covered a wide range, the average concentration was similar to the threshold limit value of 5 mg m-3 provisionally recommended by the American Conference of Governmental Industrial Hygienists. A high proportion by mass of the airborne dust was of a size which will be deposited in the nasal passages on inhalation. Images PMID:4821408

CATASTROPHIC DISRUPTION OF COMET ISON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keane, Jacqueline V.; Kleyna, Jan T.; Riesen, Timm-Emmanuel

2016-11-10

We report submillimeter 450 and 850 μ m dust continuum observations for comet C/2012 S1 (ISON) obtained at heliocentric distances 0.31–0.08 au prior to perihelion on 2013 November 28 ( r {sub h} = 0.0125 au). These observations reveal a rapidly varying dust environment in which the dust emission was initially point-like. As ISON approached perihelion, the continuum emission became an elongated dust column spread out over as much as 60″ (>10{sup 5} km) in the anti-solar direction. Deconvolution of the November 28.04 850 μ m image reveals numerous distinct clumps consistent with the catastrophic disruption of comet ISON, producingmore » ∼5.2 × 10{sup 10} kg of submillimeter-sized dust. Orbital computations suggest that the SCUBA-2 emission peak coincides with the comet's residual nucleus.« less

Operational Implications of the NATO Strategic Concept 2010 for European Countries in NATO and the EU

DTIC Science & Technology

2011-12-01

ofthe Operational Art, by Michael 0 . Krause and Cody R. Phillips (Washington D.C.: Center of Military History, 2007), 444. The level of multinational...Werner, and Wolfgang Fett. Bericht uber das gemeinsame Berliner Colloquium 2009 von Clausewitz-Gesellschafi und Bundesakademie fiir Sicherheilspolitik...Vol. 5, in Die Jahrbiicher der C/ausewitz-Gesellschafi e. V. - Jahrbuch 2009, by Werner Baach and Wolfgang Fett, 13-24. Hamburg: C lausewitz

Flood Mitigation and Response: Comparing the Great Midwest Floods of 1993 and 2008

DTIC Science & Technology

2010-12-01

The Galloway Commission ranged the damage between $12 and $16 billion; however, the report admits that its numbers were premature and not all...Foundation, June 18, 2008); Wright (2000); Sharing the Challenge; Galloway , 7; Georgianne Nienaber, “Is ‘Mother Nature’ really to Blame for the...Mattoon. 24 Wright (2000), 80–83; National Flood Programs (2007), 8; Sharing the Challenge (1994); Galloway (2005), 9. Cody and Carter, 7. 11

Committees

NASA Astrophysics Data System (ADS)

2010-01-01

INTERNATIONAL ADVISORY COMMITTEE FOR POSITRON WORKSHOP Roberto S Brusa (Italy) Michael Charlton (UK) Arnab S Ghosh (India) Franco A Gianturco (Italy) Gleb F Gribakin (UK) John Humberston (UK) Helge Knudsen (Denmark) Akos Kover (Hungary) Gaetana Laricchia (UK) Marco AP Lima (Brazil) Allen Mills (USA) Yasuyuki Nagashima (Japan) Clifford M Surko (USA) James Walters (UK) Sandra Ward (USA) LOCAL ORGANIZING COMMITTEE FOR POSITRON WORKSHOP Radu I Campeanu (York, Chairman) Jurij W Darewych (York) Allan D Stauffer (York) Cody Storry (York)