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Sample records for debris records spanning

  1. Glacial-Interglacial Climate Changes Recorded by Debris Flow Grain Size, Eastern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    D'Arcy, M. K.; Whittaker, A. C.; Roda Boluda, D. C.

    2015-12-01

    Uncertainties remain about the sensitivity of eroding landscapes to climate changes over a range of frequencies and amplitudes. Numerical models suggest that simple catchment-fan systems should be responsive to glacial-interglacial climate cycles, recording them in both sediment flux and the grain size distribution of their deposits. However these models are largely untested and the propagation of climatic signals through simple sediment routing systems remains contentious. Here, we present detailed sedimentological data from 8 debris flow fans in Owens Valley, eastern California. These fans have an exceptionally well-constrained depositional record spanning the last 120 ka, which we use to examine how sediment export has varied as a function of high-amplitude climate changes. We find a strong and sustained relationship between debris flow grain size and paleoclimate proxies over an entire glacial-interglacial cycle, with significantly coarser-grained deposits correlated with warm and dry conditions. Our data suggest these systems are highly reactive to climate forcing, with a short response timescale of <10 ka and no evidence of signal buffering, which we interpret to be driven by rapid sediment transfer from source to sink. We demonstrate that debris flow grain size follows an exponential relationship with temperature, coarsening at a rate of ~10 % per °C. Using this observation, and a known relationship between temperature and storm intensity, we propose that the climate signal recorded in these fan deposits captures changing storm intensity during the last glacial-interglacial cycle. This study offers a direct test of existing models of catchment-fan systems, confirming that glacial-interglacial climate changes can be clearly expressed in their grain size records. Our results also suggest that these debris flow deposits contain a high-resolution, testable record of past storm intensity, and that storminess is the primary control on their sedimentological

  2. Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

    Treesearch

    David R. Montgomery; Kevin M. Schmidt; William E. Dietrich; Jim. McKean

    2009-01-01

    The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium....

  3. Obliquity-paced climate change recorded in Antarctic debris-covered glaciers

    PubMed Central

    Mackay, Sean L.; Marchant, David R.

    2017-01-01

    The degree to which debris-covered glaciers record past environmental conditions is debated. Here we describe a novel palaeoclimate archive derived from the surface morphology and internal debris within cold-based debris-covered glaciers in Antarctica. Results show that subtle changes in mass balance impart major changes in the concentration of englacial debris and corresponding surface topography, and that over the past ∼220 ka, at least, the changes are related to obliquity-paced solar radiation, manifest as variations in total summer energy. Our findings emphasize solar radiation as a significant driver of mass balance changes in high-latitude mountain systems, and demonstrate that debris-covered glaciers are among the most sensitive recorders of obliquity-paced climate variability in interior Antarctica, in contrast to most other Antarctic archives that favour eccentricity-paced forcing over the same time period. Furthermore, our results open the possibility that similar-appearing debris-covered glaciers on Mars may likewise hold clues to environmental change. PMID:28186094

  4. Obliquity-paced climate change recorded in Antarctic debris-covered glaciers

    NASA Astrophysics Data System (ADS)

    Mackay, Sean L.; Marchant, David R.

    2017-02-01

    The degree to which debris-covered glaciers record past environmental conditions is debated. Here we describe a novel palaeoclimate archive derived from the surface morphology and internal debris within cold-based debris-covered glaciers in Antarctica. Results show that subtle changes in mass balance impart major changes in the concentration of englacial debris and corresponding surface topography, and that over the past ~220 ka, at least, the changes are related to obliquity-paced solar radiation, manifest as variations in total summer energy. Our findings emphasize solar radiation as a significant driver of mass balance changes in high-latitude mountain systems, and demonstrate that debris-covered glaciers are among the most sensitive recorders of obliquity-paced climate variability in interior Antarctica, in contrast to most other Antarctic archives that favour eccentricity-paced forcing over the same time period. Furthermore, our results open the possibility that similar-appearing debris-covered glaciers on Mars may likewise hold clues to environmental change.

  5. Obliquity-paced climate change recorded in Antarctic debris-covered glaciers.

    PubMed

    Mackay, Sean L; Marchant, David R

    2017-02-10

    The degree to which debris-covered glaciers record past environmental conditions is debated. Here we describe a novel palaeoclimate archive derived from the surface morphology and internal debris within cold-based debris-covered glaciers in Antarctica. Results show that subtle changes in mass balance impart major changes in the concentration of englacial debris and corresponding surface topography, and that over the past ∼220 ka, at least, the changes are related to obliquity-paced solar radiation, manifest as variations in total summer energy. Our findings emphasize solar radiation as a significant driver of mass balance changes in high-latitude mountain systems, and demonstrate that debris-covered glaciers are among the most sensitive recorders of obliquity-paced climate variability in interior Antarctica, in contrast to most other Antarctic archives that favour eccentricity-paced forcing over the same time period. Furthermore, our results open the possibility that similar-appearing debris-covered glaciers on Mars may likewise hold clues to environmental change.

  6. Debris Flows and Record Floods from Extreme Mesoscale Convective Thunderstorms over the Santa Catalina Mountains, Arizona

    USGS Publications Warehouse

    Magirl, Christopher S.; Shoemaker, Craig; Webb, Robert H.; Schaffner, Mike; Griffiths, Peter G.; Pytlak, Erik

    2007-01-01

    Ample geologic evidence indicates early Holocene and Pleistocene debris flows from the south side of the Santa Catalina Mountains north of Tucson, Arizona, but few records document historical events. On July 31, 2006, an unusual set of atmospheric conditions aligned to produce record floods and an unprecedented number of debris flows in the Santa Catalinas. During the week prior to the event, an upper-level area of low pressure centered near Albuquerque, New Mexico generated widespread heavy rainfall in southern Arizona. After midnight on July 31, a strong complex of thunderstorms developed over central Arizona in a deformation zone that formed on the back side of the upper-level low. High atmospheric moisture (2.00' of precipitable water) coupled with cooling aloft spawned a mesoscale thunderstorm complex that moved southeast into the Tucson basin. A 15-20 knot low-level southwesterly wind developed with a significant upslope component over the south face of the Santa Catalina Mountains advecting moist and unstable air into the merging storms. National Weather Service radar indicated that a swath of 3-6' of rainfall occurred over the lower and middle elevations of the southern Santa Catalina Mountains. This intense rain falling on saturated soil triggered over 250 hillslope failures and debris flows throughout the mountain range. Sabino Canyon, a heavily used recreation area administered by the U.S. Forest Service, was the epicenter of mass wasting, where at least 18 debris flows removed structures, destroyed the roadway in multiple locations, and closed public access for months. The debris flows were followed by streamflow floods which eclipsed the record discharge in the 75-year gaging record of Sabino Creek. In five canyons adjacent to Sabino Canyon, debris flows approached or excited the mountain front, compromising floow conveyance structures and flooding some homes.

  7. Glacial-interglacial climate changes recorded by debris flow fan deposits, Owens Valley, California

    NASA Astrophysics Data System (ADS)

    D'Arcy, Mitch; Roda-Boluda, Duna C.; Whittaker, Alexander C.

    2017-08-01

    It is hotly debated whether and how climate changes are recorded by terrestrial stratigraphy. Basin sediments produced by catchment-alluvial fan systems may record past climate over a variety of timescales, and could offer unique information about how climate controls sedimentation. Unfortunately, there are fundamental uncertainties about how climatic variables such as rainfall and temperature translate into sedimentological signals. Here, we examine 35 debris flow fan surfaces in Owens Valley, California, that record deposition throughout the past 125,000 years, during which climate has varied significantly. We show that the last full glacial-interglacial cycle is recorded with high fidelity by the grain size distributions of the debris flow deposits. These flows transported finer sediment during the cooler glacial climate, and became systematically coarser-grained as the climate warmed and dried. We explore the physical mechanisms that might explain this signal, and rule out changes in sediment supply through time. Instead, we propose that grain size records past changes in storm intensity, which is responsible for debris flow initiation in this area and is decoupled from average rainfall rates. This is supported by an exponential Clausius-Clapeyron-style scaling between grain size and temperature, and also reconciles with climate dynamics and the initiation of debris flows. The fact that these alluvial fans exhibit a strong, sustained sensitivity to orbital climate changes sheds new light on how eroding landscapes and their sedimentary products respond to climatic forcing. Finally, our findings highlight the importance of threshold-controlled events, such as storms and debris flows, in driving erosion and sedimentation at the Earth's surface in response to climate change.

  8. Multiproxy Paleoenvironmental Records Spanning the INTIMATE Timescale from Auckland Maar Lakes, New Zealand

    NASA Astrophysics Data System (ADS)

    Augustinus, Paul; D'Costa, Donna; Stephens, Tom; Atkin, Dan; Shane, Phil; Cochran, Ursula; Snowball, Ian; Nilsson, Andreas; Street-Perrott, Alayne; Davies, Sarah

    2010-05-01

    High-resolution Late Quaternary paleoclimate archives are preserved in the lake sediment records contained in several maar craters from the Auckland region in northern New Zealand. Tephrochronology, AMS 14C and Ar/Ar -based chronostratigraphies were developed with several lakes containing laminated sediment records spanning much of the last glacial cycle. A multi-proxy approach was taken to construct a reliable record of local and regional paleoenvironments including: pollen and diatom paleoecology, environmental magnetism, grain size, XRF geochemistry, TOC, TN, TS, organic matter δ13C, δ15N and δD, as well as δ18O in biogenic silica. Pollen and diatom analysis of records spanning the last ca 60 ka show marked vegetation changes that reflect orbital forcing, although diatoms suggest significant hydrological changes that are not reflected in the pollen. Reduction of forest with expansion of grass and shrublands at the start of the LGM (29 ka BP), is accompanied by cool, dry and windy conditions, although the situation is complex with multiple brief warmer phases punctuating the LGM. Post-glacial warming commenced ca 17.9 ka BP and is reflected in several proxies, although the pollen record does not display the marked changes displayed in many of the other proxies during the LGIT and Holocene. Some of the inferred environmental changes are similar to the nature and timing of short-duration events during the last glacial cycle from the North Atlantic region, although others appear to reflect a southern polar forcing. The multi-proxy approach used has produced one of the most complete, well-dated and high-resolution paleoenvironmental records spanning the INTIMATE timescale from the mid-latitude Southern Hemisphere with implications for the nature, timing and forcings of climate change in the Southwest Pacific region.

  9. Debris flows and Record Floods from Extreme Mesoscale Convective Thunderstorms over the Santa Catalina Mountains, Arizona

    NASA Astrophysics Data System (ADS)

    Magirl, C. S.; Shoemaker, C.; Webb, R. H.; Schaffner, M.; Griffiths, P. G.; Pytlak, E.

    2006-12-01

    Ample geologic evidence indicates early Holocene and Pleistocene debris flows from the south side of the Santa Catalina Mountains north of Tucson, Arizona, but few records document historical events. On July 31, 2006, an unusual set of atmospheric conditions aligned to produce record floods and an unprecedented number of debris flows in the Santa Catalinas. During the week prior to the event, an upper-level area of low pressure centered near Albuquerque, New Mexico generated widespread heavy rainfall in southern Arizona. After midnight on July 31, a strong and widespread complex of thunderstorms developed over the Mogollon Rim in central Arizona in a deformation zone that formed on the back side of the upper-level low. High atmospheric moisture (50 mm of precipitable water) coupled with cooling aloft spawned a mesoscale thunderstorm complex that moved southeast into the Tucson basin. These thunderstorms interacted with a low- to mid-level zone of atmospheric instability to create an initial wave of rainfall across the Tucson metropolitan area in the early morning hours. A second wave of thunderstorms and heavy rain developed over the Santa Catalina Mountain near dawn. A 15-20 knot low-level southwesterly wind developed with a significant upslope component over the south face of the Santa Catalina Mountains advecting moist and unstable air into the merging storms. NEXRAD radar indicates that a swath of 75-150 mm of rainfall occurred over the lower and middle elevations of the southern Santa Catalina Mountains in three increments: (1) from 2-6 AM, moderate intensity rainfall up to 65 mm; (2) from 6-7 AM, intensities up to 75 mm in 45 minutes; and (3) a final burst approaching 50 mm in 45 minutes from 8-9 AM. This intense rain falling on saturated soil triggered multiple debris flows in four adjacent canyons. Sabino Canyon, a heavily used recreation area administered by the U.S. Forest Service, was the epicenter of mass wasting where at least 18 debris flows removed

  10. Fish debris record the hydrothermal activity in the Atlantis II deep sediments (Red Sea)

    SciTech Connect

    Oudin, E.; Cocherie, A.

    1988-01-01

    The REE and U, Th, Zr, Hf, Sc have been analyzed in samples from Atlantis II and Shaban/Jean Charcot Deeps in the Red Sea. The high Zr/Hf ratio in some sediments indicates the presence of fish debris or of finely crystallized apatite. The positive ..sigma..REE vs P/sub 2/O/sub 5/ and ..sigma..REE vs Zr/Hf correlations show that fish debris and finely crystallized apatite are the main REE sink in Atlantis II Deep sediments as in other marine environments. The hydrothermal sediments and the fish debris concentrates have similar REE patterns, characterized by a LREE enrichment and a large positive Eu anomaly. This REE pattern is also observed in E.P.R. hydrothermal solutions. Fish debris from marine environments acquire their REE content and signature mostly from sea water during early diagenesis. The hydrothermal REE signature of Atlantis II Deep fish debris indicate that they probably record the REE signature of their hydrothermal sedimentation and diagenetic environment. The different REE signatures of the Shaban/Jean Charcot and Atlantis II Deep hydrothermal sediments suggest a sea water-dominated brine in the Shaban/Jean Charcot Deep as opposed to the predominantly hydrothermal brine in Atlantis II Deep. Atlantis II Deep fish debris are also characterized by their high U but low Th contents. Their low Th contents probably reflect the low Th content of the various possible sources (sea water, brine, sediments). Their U contents are probably controlled by the redox conditions of sedimentation.

  11. First record of sea snake (Hydrophis elegans, Hydrophiinae) entrapped in marine debris.

    PubMed

    Udyawer, Vinay; Read, Mark A; Hamann, Mark; Simpfendorfer, Colin A; Heupel, Michelle R

    2013-08-15

    Entanglement in derelict fishing gear and other marine debris is a major threat to the survival of large marine wildlife like cetaceans, seabirds and sea turtles. However, no previous reports of entanglement or entrapment have been recorded in sea snakes (Hydrophiinae). We report here on a sea snake (Hydrophis elegans) found with a ceramic washer encircling its body captured from the north-east coast of Queensland, Australia. The ring had constricted the body and over time caused extensive damage to the underlying tissues. A post-mortem examination showed the snake was severely emaciated as the ring restricted the passage of food to the stomach and intestine. This is the first record of mortality due to marine debris entrapment in sea snakes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Record of late holocene debris avalanches and lahars at Iliamna Volcano, Alaska

    USGS Publications Warehouse

    Waythomas, C.F.; Miller, T.P.; Beget, J.E.

    2000-01-01

    Iliamna Volcano is a 3053-meter high, glaciated stratovolcano in the southern Cook Inlet region of Alaska and is one of seven volcanoes in this region that have erupted multiple times during the past 10,000 yr. Prior to our studies of Iliamna Volcano, little was known about the frequency, magnitude, and character of Holocene volcanic activity. Here we present geologic evidence of the most recent eruptive activity of the volcano and provide the first outline of Late Holocene debris-avalanche and lahar formation. Iliamna has had no documented historical eruptions but our recent field investigations indicate that the volcano has erupted at least twice in the last 300 yr. Clay-rich lahar deposits dated by radiocarbon to ???1300 and ???90 yr BP are present in two major valleys that head on the volcano. These deposits indicate that at least two large, possibly deep-seated, flank failures of the volcanic edifice have occurred in the last 1300 yr. Noncohesive lahar deposits likely associated with explosive pyroclastic eruptions date to 2400-1300,>1500,???300, and <305 yr BP. Debris-avalanche deposits from recent and historical small-volume slope failures of the hydrothermally altered volcanic edifice cover most of the major glaciers on the volcano. Although these deposits consist almost entirely of hydrothermally altered rock debris and snow and ice, none of the recently generated debris avalanches evolved to lahars. A clay-rich lahar deposit that formed <90??60 radiocarbon yr BP and entered the Johnson River Valley southeast of the volcano cannot be confidently related to an eruption of Iliamna Volcano, which has had no known historical eruptions. This deposit may record an unheralded debris avalanche and lahar. ?? 2000 Elsevier Science B.V. All rights reserved.

  13. Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

    USGS Publications Warehouse

    Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.

    2009-01-01

    The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

  14. High-resolution speleothem record of precipitation from the Yucatan Peninsula spanning the Maya Preclassic Period

    NASA Astrophysics Data System (ADS)

    Medina-Elizalde, Martín; Burns, Stephen J.; Polanco-Martínez, Josué M.; Beach, Timothy; Lases-Hernández, Fernanda; Shen, Chuan-Chou; Wang, Hao-Cheng

    2016-03-01

    We produced a new high-resolution absolute U-Th dated stalagmite oxygen isotope record (δ18O) from Río Secreto, Playa del Carmen, Yucatan Peninsula (YP). This new 1434-year stalagmite record (named Itzamna after the Maya god of creation) spans the time interval between BCE 1037 and CE 397 with an average resolution of 8 ± 2 years. It provides a novel view of climate evolution over the Preclassic and early Classic periods in Maya history. To understand the controls of regional precipitation δ18O on seasonal time scales, we characterized the amount effect between precipitation amount (P) and precipitation δ18O (δP). We found that precipitation δ18O in the Yucatan Peninsula is controlled by the amount effect on seasonal scales (δP/ΔP = - 0.0137 ± 0.0031‰ per mm, r = 0.9), as suspected but never before demonstrated. Cave drip δ18O is consistent with the annual amount-weighted δ18O composition of precipitation. Multiple lines of evidence suggest that stalagmite δ18O reflects isotopic equilibrium conditions and thus stalagmite δ18O changes are interpreted to reflect precipitation amount. We determined quantitative precipitation changes from the stalagmite δ18O record following previous methods (Medina-Elizalde and Rohling, 2012). The stalagmite precipitation record suggests twelve periods of anomalous precipitation reductions ranging between about 30 and 70% below mean conditions at the time and with durations from 6 years to 31 years. Between BCE 520 and 166, the speleothem precipitation record suggests that the YP experienced an interval of high precipitation labeled the Late Preclassic Humid Period (LPHP) with precipitation maxima of up to + 86 ± 20%. Preclassic Maya cultural expansion in El Mirador Basin, located in northern Guatemala, took place while the peninsula transitioned from the LPHP to an interval with below average precipitation. We find that the Preclassic abandonment of major centers in the Mirador Basin and others around the Maya

  15. Magnitude-frequency relationships of debris flows — A case study based on field surveys and tree-ring records

    NASA Astrophysics Data System (ADS)

    Stoffel, Markus

    2010-03-01

    Debris-flow activity in a watershed is usually defined in terms of magnitude and frequency. While magnitude-frequency (M-F) relations have long formed the basis for risk assessment and engineering design in hydrology and fluvial hydraulics, only fragmentary and insufficiently specified data for debris flows exists. This paper reconstructs M-F relationships of 62 debris flows for an aggradational cone of a small (< 5 km 2), high elevation watershed in the Swiss Alps since A.D. 1863. The frequency of debris flows is obtained from tree-ring records. The magnitude of individual events is given as S, M, L, XL, and derived from volumetric data of deposits, grain size distributions of boulders, and a series of surrogates (snout elevations, tree survival, lateral spread of surges). Class S and M debris flows (< 5 × 10 3 m 3) encompass a typical size of events and have mean recurrence intervals of 5.4 (SD: 3.2) and 7.4 years (SD: 6.7), respectively. Class XL events (10 4-5 ×10 4 m 3) are, in contrast, only identified three times over the past 150 years, and major erosional activity on the cone was restricted to two of these events in 1948 and 1993. A comparison of results with hydrometeorological records shows that class L and XL events are typically triggered by advective storms (rainfall > 50 mm) in August and September, when the active layer of the rock glacier in the source area of debris flows is largest. Over the past ˜ 150 years, climate has exerted control on material released from the source area and prevented triggering of class XL events before 1922. With the projected climatic change, permafrost degradation and the potential increase in storm intensity are likely to produce " class XXL" events in the future with volumes surpassing 5 × 10 4 m 3 at the level of the debris-flow cone.

  16. KENNEDY SPACE CENTER, FLA. - During a media tour of the Columbia Debris Hangar, a video cameraman records some of the debris collected from search and recovery efforts in East Texas. About 83,000 pieces of debris from Columbia were shipped to KSC, which represents about 38 percent of the dry weight of Columbia, equaling almost 85,000 pounds. The debris is being packaged for storage in an area of the Vehicle Assembly Building.

    NASA Image and Video Library

    2003-09-11

    KENNEDY SPACE CENTER, FLA. - During a media tour of the Columbia Debris Hangar, a video cameraman records some of the debris collected from search and recovery efforts in East Texas. About 83,000 pieces of debris from Columbia were shipped to KSC, which represents about 38 percent of the dry weight of Columbia, equaling almost 85,000 pounds. The debris is being packaged for storage in an area of the Vehicle Assembly Building.

  17. Records of ocean sunfish Mola mola along the Norwegian coast spanning two centuries, 1801-2015.

    PubMed

    Frafjord, K; Bakken, T; Kubicek, L; Rønning, A-H; Syvertsen, P O

    2017-09-12

    Records of the ocean sunfish Mola mola along the Norwegian coast were compiled from all possible sources: literature, media, databases and museums. A total of 216 records were found between 1801 and 2015. They were distributed along the whole coast, except for the most north-eastern part. Nearly all years with more than five records were after 2000, with 1985 as the only exception and with a maximum of 23 records in 2014. Most, 92·4%, were from July to December. Records from before 1979 were more incidental and random and no sunfish were recorded in 54 separate years between 1879 and 2015. The northernmost record was from 70° 44' N in December 1881. No relationship between year and latitude was found. Forty-four per cent of the records were of sunfish caught in fishing gear, 27% were found stranded and 30% were observed alive at sea. A trend of a decrease in numbers of observations of living individuals and an increase in numbers of strandings as dead individuals as autumn progressed was found. Geographical differences in the three categories of observation were also found. Among the specimens whose size was recorded, most were small, <30 kg and 70 cm in total length. Only 10 were heavier than 100 kg, all these were from before 1960. Annual numbers correlated weakly with sea temperatures. This was supported by a weak negative correlation with the North Atlantic Oscillation (NAO) index, because the majority of years since 2000 had a negative NAO. © 2017 The Fisheries Society of the British Isles.

  18. Acatlán Complex, southern Mexico: Record spanning the assembly and breakup of Pangea

    NASA Astrophysics Data System (ADS)

    Damian Nance, R.; Miller, Brent V.; Keppie, J. Duncan; Brendan Murphy, J.; Dostal, Jaroslav

    2006-10-01

    New structural, geochronological, and geochemical data from the Acatlán Complex of southern Mexico show that it preserves a complete history of Pangea, from assembly to breakup. Previously interpreted to be a vestige of the Iapetus suture, the Acatlán Complex records a history that can be sequentially linked to the Rheic Ocean, the paleo-Pacific, and the Gulf of Mexico. This record is interpreted to reflect: (1) the development of a rift-passive margin on the southern flank of the Rheic Ocean in the Cambrian Ordovician; (2) the formation of an extensional regime along the formerly active northern margin of Gondwana throughout the Ordovician; (3) closure of the Rheic Ocean documented by subduction-related eclogite facies metamorphism and exhumation during the Late Devonian Mississippian; (4) Permian Triassic convergent tectonics on the paleo-Pacific margin of Pangea; and (5) interaction with a Jurassic mantle plume coeval with the opening of the Gulf of Mexico.

  19. Solid state track recorder neutron dosimetry measurements for fuel debris assessment of TMI-2 demineralizer-A

    SciTech Connect

    Ruddy, F.H.; Roberts, J.H.; Gold, R.; Preston, C.C.; Ulseth, J.A.

    1982-12-01

    Solid State Track Recorder (SSTR) neutron dosimetry measurements have been made in TMI-2 makeup Demineralizer A Cubicle in order to assess the amount of fuel debris present by means of the specific neutron activity of TMI-2 fuel. Based on recent calibration data and the results of the TMI-2 SSTR neutron dosimetry, the amount of fuel present is estimated to be 1.7 +- 0.6 kg. This value is in excellent agreement with a value determined independently by Compton recoil gamma-ray spectrometry. Sources of uncertainty in and proposed refinements of the present SSTR measurements are discussed.

  20. Increased frequency of debris flows during a regional late Holocene drought inferred from a Dead Sea sediment record

    NASA Astrophysics Data System (ADS)

    Ahlborn, Marieke; Armon, Moshe; Ben Dor, Yoav; Enzel, Yehouda; Morin, Efrat; Neugebauer, Ina; Schwab, Markus J.; Tjallingii, Rik; Brauer, Achim

    2017-04-01

    Conclusive understanding of the relationship between extreme-flow-producing torrential rainstorms and the long-term climate trend is crucial for developing future scenarios and assessing of impacts of global and regional climate change. Here we present a unique record of late Holocene torrential rainstorms, which accumulate during a multi-century regional drought in the Eastern Mediterranean, providing evidence for changes in the synoptic atmospheric circulation pattern. Shallow water sediment core DSEn from the Dead Sea provides a late Holocene record of debris flows, which are preserved in the shape of discrete graded layers in regularly laminated sediments. Present-day observations show that debris flows are induced by torrential rainstorms over the nearby steep western escarpments when precipitation exceeds 30 mm h-1 for the duration of one hour. Such rainstorms are associated with the Active Red Sea Trough synoptic atmospheric circulation pattern. We established a time series of torrential rainstorms for the time interval between 3.3 and 1.8 cal ka BP from core DSEn. Microfacies analysis revealed twenty-three discrete graded layers, which accumulate during a multi-century regional drought (3.0-2.4 cal ka BP). A higher frequency of debris flows and associated rainstorms during this drought indicates a shift in the synoptic atmospheric circulation pattern during the investigated period. We suggest that fewer passages of eastern Mediterranean cyclones caused the regional drought and thereby favored an increased frequency of the Active Red Sea Troughs in the Dead Sea basin resulting in more rainstorms during this drought. These inferences are confirmed by modern meteorological data from nearby gauging stations, which show an increased frequency of torrential rainstorms in drier climate regions. Considering the ongoing decrease in annual rainfall in the eastern Mediterranean our results offer valuable insights in linking torrential rainstorms and long-term climate

  1. Carbon isotopic record of terrestrial ecosystems spanning the Late Miocene extinction of Oreopithecus bambolii, Baccinello Basin (Tuscany, Italy).

    PubMed

    Matson, Samuel D; Rook, Lorenzo; Oms, Oriol; Fox, David L

    2012-07-01

    Oreopithecus bambolii is a Late Miocene hominoid with an extensive fossil record in the Baccinello Basin (Tuscany, Italy), and was the only western European hominoid to survive a major extinction event ca. 9.6 Ma (millions of years ago). Oreopithecus lived in the insular Tusco-Sardinian paleobioprovince, where it evolved many unique anatomical specializations that make it important for understanding the mechanisms and history of Late Miocene hominoid evolution. The eventual extinction of Oreopithecus and its associated fauna ca. 6.5 Ma has generally been attributed to interaction with species that arrived from continental Europe following tectonic collision of the Tusco-Sardinian province with mainland Italy, but palynological, paleontological, and sedimentological records indicate an environmental shift toward more variable climate across the extinction event. To explore the possibility of environmental change as a contributing factor in the extinction of Oreopithecus, we developed a stable carbon and oxygen isotope record from organic matter in paleosols from the Baccinello Basin. These data show very low temporal and spatial variability (indicating plant ecosystem stability through time and space) and provide no evidence for ecologically significant changes in floral composition spanning the extinction event, suggesting that environmental change was not an underlying cause for the extinction of Oreopithecus and its associated fauna. The carbon isotope values fall entirely within the range of isotopic variability for modern plants following the C(3) photosynthetic pathway (trees, shrubs, cool-season grasses), indicating that C(4) vegetation (warm-season grasses) was not an important component of biomass. When corrected for temporal variation in the carbon isotopic composition of atmospheric carbon dioxide, the paleosol carbon isotope values are consistent with predicted values based on modern plants and the Baccinello palynoflora, supporting the reliability of

  2. Meteoroid and orbital debris record of the Long Duration Exposure Facility's frame

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Atkinson, Dale; See, Thomas; Allbrooks, Martha; Simon, Charles; Finckenor, Miria

    1991-01-01

    The gravity stabilization feature of the NASA Long Duration Exposure Facility (LDEF), which was recovered in January 1990 after 5.7 years of continuous exposure to the LEO environment, has allowed the resolution of the flux and trajectories of impacting meteoroids and space-debris particulates. Attention is presently given to the stereoscopic video imaging results obtained for the large impact features on the LDEF's aluminum frame. Extreme directionalities appear to typify impacting particulates larger than 0.1 mm in diameter; this is not explainable in light of current models. Recommendations for further LDEF analyses to ensure the safe design of future spacecraft are presented.

  3. Detailed Sea Level Record from Barbados Spanning 13,000 to 11,000 Years Before Present

    NASA Astrophysics Data System (ADS)

    Abdul, N. A.; Mortlock, R. A.; Wright, J. D.; Fairbanks, R. G.

    2013-12-01

    Th/U dated reef-crest corals (Acropora palmata) obtained from new Barbados offshore drill cores provide a local sea level reconstruction in unprecedented detail. The time interval, 13,000 to 11,000 years before present (BP), spans the well-studied Younger Dryas pollen zone, a period that has given rise to more than three decades of sensational climate interpretations and popular press. Widely described as a time when Earth's climate reverted to "glacial-like conditions" the various hypotheses that attempt to explain the "cause" of the Younger Dryas climate event have their staunch supporters as well as their critics but there remains little consensus. The Barbados sea level record for this time interval shows that sea level continued to rise during the Younger Dryas, albeit at a slower rate than prior to 13,000 or following 11,000 years BP. The decrease in the rate of sea level rise can simply be explained by the slow expansion of the Fennoscandian Ice Sheet beginning 12,800 years BP followed by its faster demise contributing to a period of rapid sea level increase known as Melt Water Pulse 1B. We calculate the ice volume history of the Fennoscandian Ice Sheet and it compares favorably to the moraine history and ice models. The Younger Dryas climate event is most often defined by the rapid shifts in atmospheric proxies measured in ice cores from Greenland. The ice core proxies shift into and out of the Younger Dryas climate event in only a few years to a few decades. Abrupt shifts in the climate state associated with the onset and termination of the Younger Dryas as revealed in Greenland Ice cores are not expressed in the smooth Barbados deglacial sea level record. We make the case that these Greenland atmospheric records mark regional atmospheric frontal shifts and changes in air mass sources over an ice sheet that largely did not participate in the deglaciation or sea level change. As proposed decades ago, the warming of the North Atlantic between 14,000 and 13

  4. Estimating debris-flow probability using fan stratigraphy, historic records, and drainage-basin morphology, Interstate 70 highway corridor, central Colorado, U.S.A

    USGS Publications Warehouse

    Coe, J.A.; Godt, J.W.; Parise, M.; Moscariello, A.; ,

    2003-01-01

    We have used stratigraphic and historic records of debris-flows to estimate mean recurrence intervals of past debris-flow events on 19 fans along the Interstate 70 highway corridor in the Front Range of Colorado. Estimated mean recurrence intervals were used in the Poisson probability model to estimate the probability of future debris-flow events on the fans. Mean recurrence intervals range from 7 to about 2900 years. Annual probabilities range from less than 0.1% to about 13%. A regression analysis of mean recurrence interval data and drainage-basin morphometry yields a regression model that may be suitable to estimate mean recurrence intervals on fans with no stratigraphic or historic records. Additional work is needed to verify this model. ?? 2003 Millpress.

  5. Magnitude-frequency relations of debris-flows on cones: evidence from tree-ring records, field surveys and meteorological data

    NASA Astrophysics Data System (ADS)

    Stoffel, Markus

    2010-05-01

    Debris-flow activity in a watershed is usually defined in terms of magnitude and frequency. While magnitude-frequency (M-F) relations have long formed the basis for risk assessment and engineering design in hydrology and fluvial hydraulics, only fragmentary and insufficiently specified data for debris flows exists. This paper reconstructs M-F relationships of 62 debris flows for an aggradational cone of a small (< 5 km2), high elevation watershed in the Swiss Alps since A.D. 1863. The frequency of debris flows is obtained from tree-ring records. The magnitude of individual events is given as S, M, L, XL, and derived from volumetric data of deposits, grain size distributions of boulders, and a series of surrogates (snout elevations, tree survival, lateral spread of surges). Class S and M debris flows (< 5 × 103 m3) encompass a typical size of events and have mean recurrence intervals of 5.4 (SD: 3.2) and 7.4 years (SD: 6.7), respectively. Class XL events (104 - 5 × 104 m3) are, in contrast, only identified three times over the past 150 years, and major erosional activity on the cone was restricted to two of these events in 1948 and 1993. A comparison of results with hydrometeorological records shows that class L and XL events are typically triggered by advective storms (rainfall > 50 mm) in August and September, when the active layer of the rock glacier in the source area of debris flows is largest. Over the past ~150 years, climate has exerted control on material released from the source area and prevented triggering of class XL events before 1922. With the projected climatic change, permafrost degradation and the potential increase in storm intensity are likely to produce "class XXL" events in the future with volumes surpassing 5 × 104 m3 at the level of the debris-flow cone.

  6. Extensive Middle Amazonian mantling of debris aprons and plains in Deuteronilus Mensae, Mars: Implications for the record of mid-latitude glaciation

    NASA Astrophysics Data System (ADS)

    Baker, David M. H.; Head, James W.

    2015-11-01

    The mid-latitudes of Mars are host to a record of recent episodes of accumulations of ice-rich materials. The record includes debris aprons, interpreted to be debris-covered glaciers, that may represent the preserved remnants of a much more extensive ice sheet. We assessed the possibility of former glacial extents by examining debris aprons and the surrounding plains in Deuteronilus Mensae. Geomorphic units and stratigraphic relationships were mapped and documented from Mars Reconnaissance Orbiter (MRO) Context (CTX) and High Resolution Imaging Science Experiment (HiRISE) camera images, and crater retention ages were estimated from crater size-frequency distributions. Three major units are observed within the study area: debris aprons, lower plains, and upper plains. Debris aprons exhibit characteristics typical for these features documented elsewhere and in previous studies, including integrated flow lineations and patterns, convex-upward profiles, and knobby and brain terrain surface textures. A lower bound on the age for debris aprons is estimated to be 0.9 Ga. Debris aprons are superposed on a lower plains unit having a lower bound age of 3.3-3.5 Ga. A 50-100 m thick upper plains unit superposes both debris apron landforms and lower plains units and has a best-fit minimum age of 0.6 Ga. The upper plains unit exhibits characteristics of atmospherically-emplaced mantle material, including fine-grained nature, sublimation textures, cyclic layering, draping character, and widespread spatial distribution. Fracturing and subsequent sublimation/erosion of upper plains on debris aprons has contributed to many of the surface textures on debris aprons. The upper plains unit has also been eroded from the lower plains and plateaus, evidenced by isolated blocks of upper plains in the interiors of craters and on the walls and tops of plateaus. While no conclusive evidence diagnostic of former cold-based ice sheets are observed in the plains within the study region, such

  7. Frequency of the debris flow of four selected low-order streams in central Taiwan by using sequential aerial photographs and typhoon rainfall records

    NASA Astrophysics Data System (ADS)

    Chang, J.-C.; Shen, S.-M.; Liu, Y.-S.

    2003-04-01

    The Taiwan Island, located at the collision boundary of the Eurasia Plate and the Philippine Sea Plate, is characterized by intensive weathering, frequent landslides and debris flows. The latter, however, had never been regarded as a serious threat until the extensive debris flows, induced by Typhoon Herb in 1996 and/or Typhoon Toraji in 2001, caused unprecedented hazardous damages in many low-order streams, especially in the Chenyulan river basin, central Taiwan. Certain streams that remained intact in 1996 experienced dramatic change in 2001. For a better understanding of the historical records of the debris flow, a thorough examination of 17~29 versions of aerial photographs (ranging from 1951 to 2000) of four selected small catchments, which are located in the northern part of the Chenyulan basin, were conducted. The result shows that the Fengchiu stream has experienced six debris flow events over last 50 years and stands for the most vulnerable group in the basin. Statistically, the accumulation rainfall amount of an individual typhoon over 200 mm may trigger debris flow in this stream. During the same period, the other three streams did not experience any dramatic change Typhoon Toraji (>400 mm / 12 hrs). The devastating earthquake (magnitude 7.3), which occurred in 1999 and caused extensive landslides and rockfalls, is also believed playing an important role.

  8. Debris dams and the relief of headwater streams.

    Treesearch

    S.T. Lancaster; G.E. Grant

    2005-01-01

    In forested, mountain landscapes where debris flows are common, valley-spanning debris dams formed by debris-flow deposition are a common feature of headwater valleys. In this paper, we examine how wood and boulder steps, i.e., debris dams, affect longitudinal profile relief and gradient at the debris-flow-fluvial transition in three sites in the Oregon Coast Range,...

  9. Modeling debris-covered glaciers: response to steady debris deposition

    NASA Astrophysics Data System (ADS)

    Anderson, Leif S.; Anderson, Robert S.

    2016-05-01

    Debris-covered glaciers are common in rapidly eroding alpine landscapes. When thicker than a few centimeters, surface debris suppresses melt rates. If continuous debris cover is present, ablation rates can be significantly reduced leading to increases in glacier length. In order to quantify feedbacks in the debris-glacier-climate system, we developed a 2-D long-valley numerical glacier model that includes englacial and supraglacial debris advection. We ran 120 simulations on a linear bed profile in which a hypothetical steady state debris-free glacier responds to a step increase of surface debris deposition. Simulated glaciers advance to steady states in which ice accumulation equals ice ablation, and debris input equals debris loss from the glacier terminus. Our model and parameter selections can produce 2-fold increases in glacier length. Debris flux onto the glacier and the relationship between debris thickness and melt rate strongly control glacier length. Debris deposited near the equilibrium-line altitude, where ice discharge is high, results in the greatest glacier extension when other debris-related variables are held constant. Debris deposited near the equilibrium-line altitude re-emerges high in the ablation zone and therefore impacts melt rate over a greater fraction of the glacier surface. Continuous debris cover reduces ice discharge gradients, ice thickness gradients, and velocity gradients relative to initial debris-free glaciers. Debris-forced glacier extension decreases the ratio of accumulation zone to total glacier area (AAR). Our simulations reproduce the "general trends" between debris cover, AARs, and glacier surface velocity patterns from modern debris-covered glaciers. We provide a quantitative, theoretical foundation to interpret the effect of debris cover on the moraine record, and to assess the effects of climate change on debris-covered glaciers.

  10. Grade Span.

    ERIC Educational Resources Information Center

    Renchler, Ron

    2000-01-01

    This issue reviews grade span, or grade configuration. Catherine Paglin and Jennifer Fager's "Grade Configuration: Who Goes Where?" provides an overview of issues and concerns related to grade spans and supplies profiles of eight Northwest schools with varying grade spans. David F. Wihry, Theodore Coladarci, and Curtis Meadow's…

  11. KENNEDY SPACE CENTER, FLA. - Workers in the Columbia Debris Hangar record the first items of the STS-107 debris to be transferred to storage in the Vehicle Assembly Building. About 83,000 pieces were shipped to KSC during search and recovery efforts in East Texas.

    NASA Image and Video Library

    2003-09-02

    KENNEDY SPACE CENTER, FLA. - Workers in the Columbia Debris Hangar record the first items of the STS-107 debris to be transferred to storage in the Vehicle Assembly Building. About 83,000 pieces were shipped to KSC during search and recovery efforts in East Texas.

  12. Pleistocene ice-rafted debris events recorded at the Agulhas Plateau - indicators of intermittent Indian-Atlantic gateway closure

    NASA Astrophysics Data System (ADS)

    Ziegler, M.; Hall, I. R.; Siret, P. J.; Zahn, R.

    2012-04-01

    Interocean exchange of heat and salt around South Africa - the so called 'Agulhas Leakage' - is thought to be a key link in the maintenance of the Atlantic meridional overturning circulation (AMOC). It takes place at the Agulhas Retroflection, largely by the intermittent shedding of enormous rings that penetrate into the South Atlantic Ocean (Lutjeharms, 1996, Biastoch et al., 2008; Beal et al., 2011). Recent palaeoceanographic studies suggest that variability in the latitudinal position of the subtropical front (STF) in the Southern Ocean, act as a gatekeeper for the Agulhas retroflection and moreover, that a variable northward migration of the STF potentially modulated the severity of glacial periods by altering the amount of Agulhas leakage with consequences for the AMOC (Bard and Rickaby, 2009). Here we present a high-resolution record of ice rafted debris (IRD) from the southern Agulhas Plateau (sediment core MD02-2588, 41°19,90 S and 25°49,70 E, 2907 m water depth) covering the last 350,000 years. We find distinct millennial scale events with high abundances of IRD in the sediments. Scanning-electron microscope analysis of individual grains shows a wide range of morphologies, with a high degree of angularity being a dominant feature, with surface microfeatures (linear fractures, grooves and troughs) that are typical for glacial origin and transport. We interpret these IRD events as indicators for a northward shift of the Southern Ocean frontal system, thereby allowing sufficient cooling and iceberg survivability as far north as the Agulhas Plateau. Our proxy record suggests significant millennial scale variability of the frontal movements throughout the last three glacial cycles. Largest IRD peaks occur during marine isotope stage 8 (~300 ka BP) and hence during a period for which an extreme northward shift in the STF has been identified previously (Bard and Rickaby, 2009). We compare our IRD record with records of millennial scale climate variability in

  13. A high-resolution paleoclimate record spanning the past 25,000 years in southern East Africa.

    PubMed

    Johnson, Thomas C; Brown, Erik T; McManus, James; Barry, Sylvia; Barker, Philip; Gasse, François

    2002-04-05

    High-resolution profiles of the mass accumulation rate of biogenic silica and other geochemical proxies in two piston cores from northern Lake Malawi provide a climate signal for this part of tropical Africa spanning the past 25,000 years. The biogenic silica mass accumulation rate was low during the relatively dry late Pleistocene, when the river flux of silica to the lake was suppressed. Millennial-scale fluctuations, due to upwelling intensity, in the late Pleistocene climate of the Lake Malawi basin appear to have been closely linked to the Northern Hemisphere climate until 11 thousand years ago. Relatively cold conditions in the Northern Hemisphere coincided with more frequent north winds over the Malawi basin, perhaps resulting from a more southward migration of the Intertropical Convergence Zone.

  14. Geomorphic variation in riparian tree mortality and stream coarse woody debris recruitment from record flooding in a coastal plain stream

    Treesearch

    Brian J. Palik; Stephen W. Golladay; P. Charles Goebel; Brad W. Taylor

    1998-01-01

    Large floods are an important process controlling the structure and function of stream ecosystems. One of the ways floods affect streams is through the recruitment of coarse woody debris from stream-side forests. Stream valley geomorphology may mediate this interaction by altering flood velocity, depth, and duration. Little research has examined how floods and...

  15. A Deep-Sea Coral Clumped Isotope Record From Southern Ocean Intermediate Water Spanning the Most Recent Glacial Termination

    NASA Astrophysics Data System (ADS)

    Hines, S.; Eiler, J. M.; Adkins, J. F.

    2015-12-01

    Movement of intermediate waters plays an important role in global heat and carbon transport in the ocean and changes in their distribution are closely tied to glacial-interglacial climate change. Ocean temperature is necessarily linked to circulation because density is a function of temperature and salinity. In the modern ocean, stratification is dominated by differences in temperature, but this may not have been the case in the past. Coupled radiocarbon and U/Th dates on deep-sea Desmophyllum dianthus corals allow for the reconstruction of past intermediate water circulation rates. The addition of temperature measurements further aids in understanding of the mechanisms driving the observed signals, since there are different boundary conditions for resetting these two properties at the surface. In the modern Southern Ocean, temperature and radiocarbon are broadly correlated. At the surface there are meridional gradients of these properties, with colder, more radiocarbon-depleted water closer to the Antarctic continent. We present a high-resolution time series of clumped isotope temperature measurements on 30 corals spanning the Last Glacial Maximum through the end of the Antarctic Cold Reversal (ACR). These samples have previously been U/Th and radiocarbon dated. Corals were collected south of Tasmania from depths of between ~1450 - 1900 m, with 70% between 1500 and 1700 m. Uranium and thorium measurements were made by MC-ICP-MS on a ThermoFinnigan Neptune, radiocarbon was measured by AMS at the KCCAMS Laboratory at UC Irvine, and clumped isotope temperatures were measured on a MAT 253 attached to an automated carbonate preparation line. Preliminary results show constant temperature between ~20 - 18 ka, a gradual rise of ~6 ºC through Heinrich Stadial 1 (~18 - 15 ka), an abrupt drop of ~7 ºC directly preceeding the start of the Bølling at 14.7 ka, and another slight rise of ~4 ºC through the ACR (14.7 - 12.8 ka). The addition of clumped isotope temperatures to

  16. Enhancing debris flow modeling parameters integrating Bayesian networks

    NASA Astrophysics Data System (ADS)

    Graf, C.; Stoffel, M.; Grêt-Regamey, A.

    2009-04-01

    Applied debris-flow modeling requires suitably constraint input parameter sets. Depending on the used model, there is a series of parameters to define before running the model. Normally, the data base describing the event, the initiation conditions, the flow behavior, the deposition process and mainly the potential range of possible debris flow events in a certain torrent is limited. There are only some scarce places in the world, where we fortunately can find valuable data sets describing event history of debris flow channels delivering information on spatial and temporal distribution of former flow paths and deposition zones. Tree-ring records in combination with detailed geomorphic mapping for instance provide such data sets over a long time span. Considering the significant loss potential associated with debris-flow disasters, it is crucial that decisions made in regard to hazard mitigation are based on a consistent assessment of the risks. This in turn necessitates a proper assessment of the uncertainties involved in the modeling of the debris-flow frequencies and intensities, the possible run out extent, as well as the estimations of the damage potential. In this study, we link a Bayesian network to a Geographic Information System in order to assess debris-flow risk. We identify the major sources of uncertainty and show the potential of Bayesian inference techniques to improve the debris-flow model. We model the flow paths and deposition zones of a highly active debris-flow channel in the Swiss Alps using the numerical 2-D model RAMMS. Because uncertainties in run-out areas cause large changes in risk estimations, we use the data of flow path and deposition zone information of reconstructed debris-flow events derived from dendrogeomorphological analysis covering more than 400 years to update the input parameters of the RAMMS model. The probabilistic model, which consistently incorporates this available information, can serve as a basis for spatial risk

  17. High resolution stalagmite climate record from the Yucatán Peninsula spanning the Maya terminal classic period

    NASA Astrophysics Data System (ADS)

    Medina-Elizalde, Martín; Burns, Stephen J.; Lea, David W.; Asmerom, Yemane; von Gunten, Lucien; Polyak, Victor; Vuille, Mathias; Karmalkar, Ambarish

    2010-09-01

    The decline of the Classic Maya civilization was complex and geographically variable, and occurred over a ~ 150-year interval, known as the Terminal Classic Period (TCP, C.E. 800-950). Paleoclimate studies based on lake sediments from the Yucatán Peninsula lowlands suggested that drought prevailed during the TCP and was likely an important factor in the disintegration of the Classic Maya civilization. The lacustrine evidence for decades of severe drought in the Yucatán Peninsula, however, does not readily explain the long 150-year socio-political decline of the Classic Maya civilization. Here we present a new, absolute-dated, high-resolution stalagmite δ18O record from the northwest Yucatán Peninsula that provides a much more detailed picture of climate variability during the last 1500 years. Direct calibration between stalagmite δ18O and rainfall amount offers the first quantitative estimation of rainfall variability during the Terminal Classic Period. Our results show that eight severe droughts, lasting from 3 to 18 years, occurred during major depopulation events of Classic Maya city-states. During these droughts, rainfall was reduced by 52% to 36%. The number and short duration of the dry intervals help explain why the TCP collapse of the Mayan civilization occurred over 150 years.

  18. Ophiolites debris in the Aveto unit (Trebbia Valley, Northern Apennines, Italy): a record of the Early Oligocene apenninic foredeep?

    NASA Astrophysics Data System (ADS)

    Catanzariti, R.; Cerrina Feroni, A.; Marroni, M.; Ottria, G.; Pandolfi, L.

    2003-04-01

    In the Northern Apennines, the Aveto succession, belonging to the Subligurian domain, sedimented during the Early Oligocene. This time represents a main step in the Alps-Apennines evolution characterized by several geodynamic events such as the Voltri Group exhumation or the development of the Calk-alcaline volcanism The Aveto succession represents a complex depositional system outcropping in the Northern Apennines located, in the palinspastic reconstructions, between the Mesoalpine belt and the Tuscan Domain. The occurrence of andesitic debris in the Aveto succession can be considered a fondamental tool to understand the geodynamic processes that occurred in the Alps-Apennines linkage area. The Aveto succession is characterized by an almost 500m thick turbiditic sequence (the so-called Aveto Formation) characterized by andesitic-bearing coarse grained arenites and conglomerates. The age of this succession has been determined using Nannofossils assemblage that indicates the biozone MNP23 (Early Oligocene). An age of 32ma (Early Oligocene) has been also provided by radiometric datings on the andesitic clasts. Up to now the basement and the top of the Aveto succession have never been recognized because of pervasive deformations related to the the thrusting of the Liguride units onto the Subligurian and Tuscan ones. New biostratigraphic and field data, derived from the new 1:50.000 italian mapping project, have evidenced, the presence of a new stratigraphic unit at the top of Aveto succession cropping out in the Trebbia Valley. This unit is characterized by a sudden change in the sedimentary facies with development of choesive debris flow characterized by the occurence of ophiolitic fragments.The ophiolitic debris is made up of serpentinized peridotites, basalts, radiolarites and limestones of Late Cretaceous-Paleocene age. According to theirs age, petrographic features and absence of metamorphism, these clast can be related to a typical Liguride succession that

  19. Woody debris

    Treesearch

    Donna B. Scheungrab; Carl C. Trettin; Russ Lea; Martin F. Jurgensen

    2000-01-01

    Woody debris can be defined as any dead, woody plant material, including logs, branches, standing dead trees, and root wads. Woody debris is an important part of forest and stream ecosystems because it has a role in carbon budgets and nutrient cycling, is a source of energy for aquatic ecosystems, provides habitat for terrestrial and aquatic organisms, and contributes...

  20. Orbital Debris

    NASA Technical Reports Server (NTRS)

    Kessler, D. J. (Compiler); Su, S. Y. (Compiler)

    1985-01-01

    Earth orbital debris issues and recommended future activities are discussed. The workshop addressed the areas of environment definition, hazards to spacecraft, and space object management. It concluded that orbital debris is a potential problem for future space operations. However, before recommending any major efforts to control the environment, more data are required. The most significant required data are on the population of debris smaller than 4 cm in diameter. New damage criteria are also required. When these data are obtained, they can be combined with hypervelocity data to evaluate the hazards to future spacecraft. After these hazards are understood, then techniques to control the environment can be evaluated.

  1. Exploring Northern Hemisphere Ice Sheet Variability in the Pliocene using Ice Rafted Debris Records and Iceberg Trajectory Modelling

    NASA Astrophysics Data System (ADS)

    Smith, Y.; Haywood, A. M.; Hill, D. J.; Dolan, A. M.; Dowsett, H. J.; Robinson, M. M.

    2015-12-01

    The Greenland Ice Sheet (GRIS) contains approximately 7.36m of sea level equivalent that could melt over the next 1000 years. Therefore understanding the response of the GRIS during past warm periods is fundamentally important. The Late Pliocene (LP) has similarities to the projected 21st Century climate, and there is enough available data to constrain ice sheet and iceberg modelling studies, thus it make the LP a useful palaeoclimate modelling target. Within the LP, the mid Piacenzian Warm Period (mPWP) is particularly well documented. The USGS PRISM (Pliocene Research, Interpretation & Synoptic Mapping) project focuses on the mPWP (3.26 -3.025Ma) and was chosen for the similarities to modern in paleogeography, CO2 levels and because fossil assemblages of LP foraminifera are largely composed of extant species. Data sets of PRISM are used as boundary conditions in climate models which simulate ice sheet and iceberg scenarios in warm conditions of the mid/high latitudes. In the mPWP, temperatures were 2-3°C warmer than present and CO2 level was about 405ppmv. Multi-climate and multi-ice sheet modelling studies show retreat in the GRIS to higher elevation. However, immediately prior to the mPWP, Marine Isotope Stage M2 (3.3Ma) is a cold period in the warmer LP background. Localized evidence of ice during the M2 exists but if a larger northern hemisphere (NH) glaciation occurred, evidence has been erased. Evidence shows a drop in sea level up to 60m and CO2 at 220ppmv. Climate models show a medium/large NH ice cover is plausible at the M2. The exact extent during both warm and cold periods in the LP remains unclear. Evidence of this extent can be seen in marine sediment cores as ice rafted debris (IRD) which helps decipher the state of the ice sheet. The distribution of mPWP North Atlantic IRD in space and time tells us about the location of iceberg-producing glaciers of the NH. Using the M2 and mPWP climate scenarios, we have modelled iceberg trajectories to see

  2. Debris Flow

    NASA Image and Video Library

    2015-04-14

    This image captured by NASA 2001 Mars Odyssey spacecraft shows downslope movement of material from the hill at the top of the image. Linear ridges and channels are visible on the surface to the debris flow deposit.

  3. STS-125 Orbital Debris

    NASA Image and Video Library

    2009-07-02

    JSC2010-E-054445 (2 July 2009) --- Members of the Orbital Debris Program Office and the Hypervelocity Impact Technology Facility at JSC record images of impact craters and other surface data on the returned Wide Field and Planetary Camera (WFPC-2) of the Hubble Space Telescope. Inspection took place at the Goddard Space Flight Center during the summer of 2009. Photo credit: NASA or National Aeronautics and Space Administration

  4. Evolution of a giant debris flow in the transitional mountainous region between the Tibetan Plateau and the Qinling Mountain range, Western China: Constraints from broadband seismic records

    NASA Astrophysics Data System (ADS)

    Huang, Xinghui; Li, Zhengyuan; Yu, Dan; Xu, Qiang; Fan, Junyi; Hao, Zhen; Niu, Yanping

    2017-10-01

    The catastrophic Sanyanyu and Luojiayu debris flows, which were induced by heavy rainfall, occurred at approximately midnight, August 7th, 2010 (Beijing time, UTC + 8) and claimed 1,765 lives. Most seismic stations located within 150 km did not detect the debris flows except for the closest seismic station, ZHQ, indicating that the seismic signals generated by the debris flows decayed rapidly. We analyzed broadband seismic signals from the ZHQ seismic station, beginning approximately 20 min before the outbreak of the Sanyanyu debris flow, to rebuild its evolution processes. Seismic signals can detect development of the Sanyanyu debris flow approximately 20 min after a heavy rain started falling in its initiation area; this time was characterized by a gradual increase in seismic amplitude accompanied by a series of spike signals that were probably generated by rock collapses within the catchment. The frequency contents and the characteristics of seismic signals before and after 23:33:15 (T1) are distinctively different, which we interpret as being generated by a large quantity of flowing material entering the main channel, marking the formation of the Sanyanyu debris flow. We attribute seismic amplitude increases between 23:33:15 (T1) and 23:34:26 (T2) and between 23:35:40 (T3) and 23:36:49 (T4) to entrainment of the deposit material after initiation of the debris flow and to its flow through a colluvial deposit area, respectively. The main frequency band broadening of seismic signals after 23:37:30 (T5) is believed to have been induced by impacts between the flowing material and check dams.

  5. Columbia Debris

    NASA Image and Video Library

    2003-05-06

    George D'Heilly and John Cassanto, scientists with Instrumentation Technology Associates, Inc., display for the media part of the apparatus recovered during the search for Columbia debris. It was part of the Commercial ITA Biomedical Experiments payload on mission STS-107 that included the Growth of Bacterial Biofilm on Surfaces during Spaceflight (GOBBSS) experiment and crystals grown for cancer research. The GOBBSS experiment was sponsored by the Planetary Society, with joint participation of an Israeli and a Palestinian student, and developed by the Israeli Aerospace Medical Institute and JSC Astrobiology Center.

  6. Galactic Archaeology and Minimum Spanning Trees

    NASA Astrophysics Data System (ADS)

    MacFarlane, B. A.; Gibson, B. K.; Flynn, C. M. L.

    2016-10-01

    Chemical tagging of stellar debris from disrupted open clusters and associations underpins the science cases for next-generation multi-object spectroscopic surveys. As part of the Galactic Archaeology project TraCD (Tracking Cluster Debris), a preliminary attempt at reconstructing the birth clouds of now phase-mixed thin disk debris is undertaken using a parametric minimum spanning tree (MST) approach. Empirically-motivated chemical abundance pattern uncertainties (for a 10-dimensional chemistry-space) are applied to NBODY6-realized stellar associations dissolved into a background sea of field stars, all evolving in a Milky Way potential. We demonstrate that significant population reconstruction degeneracies appear when the abundance uncertainties approach ˜0.1 dex and the parameterized MST approach is employed; more sophisticated methodologies will be required to ameliorate these degeneracies.

  7. 2. View northeast. South elevation Westminster span, link span, ...

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

    2. View northeast. South elevation - Westminster span, link span, Walpole span. - Walpole-Westminster Bridge, Spanning Connecticut River between Walpole, NH & Westminster, VT, Walpole, Cheshire County, NH

  8. 1. View south. North elevation Walpole span, link span, ...

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

    1. View south. North elevation - Walpole span, link span, and Westminster span. - Walpole-Westminster Bridge, Spanning Connecticut River between Walpole, NH & Westminster, VT, Walpole, Cheshire County, NH

  9. The impact of debris on marine life.

    PubMed

    Gall, S C; Thompson, R C

    2015-03-15

    Marine debris is listed among the major perceived threats to biodiversity, and is cause for particular concern due to its abundance, durability and persistence in the marine environment. An extensive literature search reviewed the current state of knowledge on the effects of marine debris on marine organisms. 340 original publications reported encounters between organisms and marine debris and 693 species. Plastic debris accounted for 92% of encounters between debris and individuals. Numerous direct and indirect consequences were recorded, with the potential for sublethal effects of ingestion an area of considerable uncertainty and concern. Comparison to the IUCN Red List highlighted that at least 17% of species affected by entanglement and ingestion were listed as threatened or near threatened. Hence where marine debris combines with other anthropogenic stressors it may affect populations, trophic interactions and assemblages. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Microplastic debris in sandhoppers

    NASA Astrophysics Data System (ADS)

    Ugolini, A.; Ungherese, G.; Ciofini, M.; Lapucci, A.; Camaiti, M.

    2013-09-01

    Adults of the sandhopper Talitrus saltator were fed with dry fish food mixed with polyethylene microspheres (diameter 10-45 μm). Observations of homogenized guts revealed the presence of microspheres independently of their dimensions. The gut resident time (GRT) was recorded and most of the microspheres are expelled in 24 h. Microspheres are totally expelled in one week. Preliminary investigations did not show any consequence of microsphere ingestion on the survival capacity in the laboratory. FT-IR analyses carried out on faeces of freshly collected individuals revealed the presence of polyethylene and polypropylene. This confirms that microplastic debris could be swallowed by T. saltator in natural conditions.

  11. 3. VIEW NORTH SHOWING FIXED SPAN, COVERED SPAN, MOVEABLE TRANSITION ...

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

    3. VIEW NORTH SHOWING FIXED SPAN, COVERED SPAN, MOVEABLE TRANSITION SPAN AND PONTOON FLOATING SPAN - Lacey V. Murrow Memorial Floating Bridge, Spanning Lake Washington at I-90, Seattle, King County, WA

  12. Atmospheric lead and heavy metal pollution records from a Belgian peat bog spanning the last two millenia: human impact on a regional to global scale.

    PubMed

    De Vleeschouwer, François; Gérard, Laëtitia; Goormaghtigh, Catherine; Mattielli, Nadine; Le Roux, Gaël; Fagel, Nathalie

    2007-05-15

    Europe has been continuously polluted throughout the last two millennia. During the Roman Empire, these pollutions were mainly from ore extraction and smelting across Europe. Then, during the Middle Ages and the Early times of Industrial revolution (i.e. 1750), these pollutions extended to coal burning and combustion engine. Belgian ombrotrophic peat bogs have proved an effective archive of these pollutants and provide the opportunity to reconstruct the history of atmospheric deposition in NW Europe. The results of recent and past trace metal accumulation and Pb isotopes from a one-meter peat core (in the Misten peat bog) have been derived using XRF and Nu-plasma MC-ICP-MS. Combined with (14)C and (210)Pb dates these data have enabled us to trace fluxes in anthropogenic pollution back to original Roman times. Several periods of well-known Pb pollution events are clearly recorded including the Early and Late Roman Empire, the Middle Ages and the second industrial revolution. Also recorded is the introduction of leaded gasoline, and more recently the introduction of unleaded gasoline. Lead isotopes in this site have also enabled us to fingerprint several regional and global sources of anthropogenic particles.

  13. A 38,000-year record of floods and debris flows in the Ilo region of southern Peru and its relation to El Niño events and great earthquakes

    USGS Publications Warehouse

    Keefer, David K.; Moseley, Michael E.; DeFrance, Susan D.

    2003-01-01

    Previous work throughout the Ilo region of south coastal Peru has documented the existence of flood and debris-flow deposits produced by two El Niño events evidently much more severe than any in recent history. These two events have been dated to ca. AD 1300–1400 and AD 1607–08. The Late Pleistocene to Holocene record of older sedimentary deposits in this region is dominated by flood and debris-flow deposits of similar scale. These older deposits have been described and dated from three coastal, alluvial-fan sites. These deposits, which are as old as 38 200 years, are dominated by massive debris-flow deposits, several tens of cm thick, typically composed of cobble- and boulder-sized clasts in a matrix of silty sand, with characteristics indicating generation by heavy rainfall in an arid environment. Twenty-two radiocarbon dates and a single infrared-stimulated luminescence date show that particularly severe El Niño events occurred throughout the Late Pleistocene and two of three divisions of the Holocene with significantly different frequencies. The period of greatest activity was during the Early Holocene when at least six such events took place during a period of ca. 3600 years, beginning near the end of the Younger Dryas ca. 12 000 years ago. One of these events produced a debris flow that may have caused abandonment of the Paleo-Indian site at Quebrada Tacahuay, one of the oldest on the Andean coast. No severe events took place during the Middle Holocene between ca. 8400 and 5300 years ago, when a wide variety of other paleoclimate proxy records indicate that the El Niño–Southern Oscillation regime was particularly weak. Since ca. 5300 years ago, four of these severe events have taken place. The Late Pleistocene sequence is constrained by only two dates, which indicate that at least ten severe events took place between ca. 38 200 and 12 900 years ago. Mechanisms probably responsible for generating these large-scale deposits include: (1)

  14. Space Shuttle Debris Transport

    NASA Technical Reports Server (NTRS)

    Gomez, Reynaldo J., III

    2010-01-01

    This slide presentation reviews the assessment of debris damage to the Space Shuttle, and the use of computation to assist in the space shuttle applications. The presentation reviews the sources of debris, a mechanism for determining the probability of damaging debris impacting the shuttle, tools used, eliminating potential damaging debris sources, the use of computation to assess while inflight damage, and a chart showing the applications that have been used on increasingly powerful computers simulate the shuttle and the debris transport.

  15. A 12,000-Year-Long, Annually-Resolved Varve Record Spanning the Last Interglacial from Lake Bosumtwi, Southern Ghana

    NASA Astrophysics Data System (ADS)

    McKay, N.; Overpeck, J. T.; Shanahan, T. M.; Peck, J. A.; Heil, C. W.; King, J. W.; Scholz, C. A.

    2012-12-01

    The impact of continued global warming on the likelihood of severe drought in sub-Saharan West Africa remains uncertain, as climate models generally do not simulate realistic climate dynamics in the region and have inconsistent projections for the future. The Last Interglacial period (LIG), occurring between 128 and 116 thousand years ago, is a partial analog for future warming because at its peak, global temperatures were slightly higher, and this warming was accentuated in Northern Hemisphere terrestrial summer temperatures. Here we present a new, annually-resolved, 12,100-year-long varve record for the LIG from Lake Bosumtwi in southern Ghana (6.5°N, 1.4°W). The abundance of terrigenous elements in the sediment, varve thickness, and the isotope geochemistry and mineralogy of authigenic carbonates in the sediment were used to infer changes in lake level. The varve chronology, varve thickness and elemental abundance records were developed with a new ensemble approach that allows for a more robust determination of uncertainty in the record. The new records reveal a dynamic history of hydrologic variability during the LIG. The LIG lake highstand was lower and shorter-lived than the the prolonged highstand in the early Holocene, and unlike the Holocene, the lake never overflowed during LIG. The overall drier conditions during the LIG are most likely driven by amplified precessional forcing during the interval, resulting in a northward shift in the rainbelt. The LIG, like the Holocene, had two distinct millennial-scale moist intervals, from 125 - 123 and 121 - 120 ka. In both the LIG and the Holocene, these peaks occurred during times of precession-driven insolation maxima in July and October, corresponding to the two rainy seasons in the modern climatology. This suggests that, at least during interglacials, prolonged wet conditions occur at the lake when rainy season insolation is highest. Over the course of the LIG, lake level generally tracked sea surface

  16. SPAN: Ocean science

    NASA Technical Reports Server (NTRS)

    Thomas, Valerie L.; Koblinsky, Chester J.; Webster, Ferris; Zlotnicki, Victor; Green, James L.

    1987-01-01

    The Space Physics Analysis Network (SPAN) is a multi-mission, correlative data comparison network which links space and Earth science research and data analysis computers. It provides a common working environment for sharing computer resources, sharing computer peripherals, solving proprietary problems, and providing the potential for significant time and cost savings for correlative data analysis. This is one of a series of discipline-specific SPAN documents which are intended to complement the SPAN primer and SPAN Management documents. Their purpose is to provide the discipline scientists with a comprehensive set of documents to assist in the use of SPAN for discipline specific scientific research.

  17. Disaster Debris Recovery Database - Recovery

    EPA Pesticide Factsheets

    The US EPA Region 5 Disaster Debris Recovery Database includes public datasets of over 6,000 composting facilities, demolition contractors, transfer stations, landfills and recycling facilities for construction and demolition materials, electronics, household hazardous waste, metals, tires, and vehicles in the states of Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia and Wisconsin.In this update, facilities in the 7 states that border the EPA Region 5 states were added to assist interstate disaster debris management. Also, the datasets for composters, construction and demolition recyclers, demolition contractors, and metals recyclers were verified and source information added for each record using these sources: AGC, Biocycle, BMRA, CDRA, ISRI, NDA, USCC, FEMA Debris Removal Contractor Registry, EPA Facility Registry System, and State and local listings.

  18. Disaster Debris Recovery Database - Landfills

    EPA Pesticide Factsheets

    The US EPA Region 5 Disaster Debris Recovery Database includes public datasets of over 6,000 composting facilities, demolition contractors, transfer stations, landfills and recycling facilities for construction and demolition materials, electronics, household hazardous waste, metals, tires, and vehicles in the states of Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia and Wisconsin.In this update, facilities in the 7 states that border the EPA Region 5 states were added to assist interstate disaster debris management. Also, the datasets for composters, construction and demolition recyclers, demolition contractors, and metals recyclers were verified and source information added for each record using these sources: AGC, Biocycle, BMRA, CDRA, ISRI, NDA, USCC, FEMA Debris Removal Contractor Registry, EPA Facility Registry System, and State and local listings.

  19. HEO space debris orbit predictions.

    NASA Astrophysics Data System (ADS)

    Gregorowicz, Dorota; Pospieszynski, Remigiusz; Golembiewska, Justyna; Wnuk, Edwin

    2012-07-01

    HEO (Highly Elliptical Orbit) satellites are objects with an elliptic orbit with a low-altitude perigee and a high-altitude apogee. Perigee mainly cross the LEO orbits and apogee reaches regions above GEO orbits. Number of satellites on the orbits are old racket bodies and other space debris. Most of HEO objects has the eccentricity more than 0.7. Many trackable objects are included in the NORAD TLE Catalogue but much more small debris exist which we could not track. Objects on as highly elliptical orbit are very danger for satellites in LEO region because of increasing velocity near the perigee. In order to calculate the trajectory of space debris we have to take into account force model consisting of geopotential, luni-solar effects, solar radiation pressure and for objects with low-altitude of perigee, atmospheric drag. This last perturbation is very important to calculate orbits with high accuracy but also one of the hardest to predict. Many atmospheric space debris objects parameters should be taken into account in this case, but we do not have sufficient data from observations, in particular S/M (area-to-mass) ratio. Fortunately we have some archival data for some debris included in TLE Catalogue, which are very helpful to estimate the approximate value of the parameter. In this paper we present the results of calculations of orbit predictions for short and medium time span (up to several weeks). We tried to designate the S/M parameter for some HEO objects from archival data from the TLE Catalogue and predict its orbital elements for several weeks. With better knowledge about approximate mean value of the S/M parameter we are able to improve the accuracy of predicted orbits.

  20. Orbital Debris: A Chronology

    NASA Technical Reports Server (NTRS)

    Portree, Davis S. F. (Editor); Loftus, Joseph P., Jr. (Editor)

    1999-01-01

    This chronology covers the 37-year history of orbital debris concerns. It tracks orbital debris hazard creation, research, observation, experimentation, management, mitigation, protection, and policy. Included are debris-producing, events; U.N. orbital debris treaties, Space Shuttle and space station orbital debris issues; ASAT tests; milestones in theory and modeling; uncontrolled reentries; detection system development; shielding development; geosynchronous debris issues, including reboost policies: returned surfaces studies, seminar papers reports, conferences, and studies; the increasing effect of space activities on astronomy; and growing international awareness of the near-Earth environment.

  1. Roll Call Debris - Race

    EPA Pesticide Factsheets

    Marine debris degrades ocean habitats, endangers marine and coastal wildlife, causes navigation hazards, results in economic losses to industry and governments, and threatens human health and safety. EPA Pacific Southwest (Region 9) is tapping existing programs and resources to advance the prevention, reduction and clean-up of marine debris in the North Pacific Ocean. EPA Pacific Southwest activities build upon specific recommendations of the Interagency Marine Debris Coordinating Committee by targeting threats and sources of debris and responding to debris impacts. EPA is initiating a three-pronged effort to reduce sources of marine debris, prevent trash from entering the oceans, and assess the human and ecosystem impacts and potential for cleanup.

  2. Fleet Debris Levels

    EPA Pesticide Factsheets

    Marine debris degrades ocean habitats, endangers marine and coastal wildlife, causes navigation hazards, results in economic losses to industry and governments, and threatens human health and safety. EPA Pacific Southwest (Region 9) is tapping existing programs and resources to advance the prevention, reduction and clean-up of marine debris in the North Pacific Ocean. EPA Pacific Southwest activities build upon specific recommendations of the Interagency Marine Debris Coordinating Committee by targeting threats and sources of debris and responding to debris impacts. EPA is initiating a three-pronged effort to reduce sources of marine debris, prevent trash from entering the oceans, and assess the human and ecosystem impacts and potential for cleanup.

  3. Special Report Debris - Race

    EPA Pesticide Factsheets

    Marine debris degrades ocean habitats, endangers marine and coastal wildlife, causes navigation hazards, results in economic losses to industry and governments, and threatens human health and safety. EPA Pacific Southwest (Region 9) is tapping existing programs and resources to advance the prevention, reduction and clean-up of marine debris in the North Pacific Ocean. EPA Pacific Southwest activities build upon specific recommendations of the Interagency Marine Debris Coordinating Committee by targeting threats and sources of debris and responding to debris impacts. EPA is initiating a three-pronged effort to reduce sources of marine debris, prevent trash from entering the oceans, and assess the human and ecosystem impacts and potential for cleanup.

  4. SPAN: Astronomy and astrophysics

    NASA Technical Reports Server (NTRS)

    Thomas, Valerie L.; Green, James L.; Warren, Wayne H., Jr.; Lopez-Swafford, Brian

    1987-01-01

    The Space Physics Analysis Network (SPAN) is a multi-mission, correlative data comparison network which links science research and data analysis computers in the U.S., Canada, and Europe. The purpose of this document is to provide Astronomy and Astrophysics scientists, currently reachable on SPAN, with basic information and contacts for access to correlative data bases, star catalogs, and other astrophysic facilities accessible over SPAN.

  5. 4. DETAIL VIEW FIXED SPAN INCLUDING TRUSS, MOVEABLE SPAN WHICH ...

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

    4. DETAIL VIEW FIXED SPAN INCLUDING TRUSS, MOVEABLE SPAN WHICH THE NEXT UNIT TO THE RIGHT, AND FIRST UNIT OF PONTOON FLOATING SPAN. - Lacey V. Murrow Memorial Floating Bridge, Spanning Lake Washington at I-90, Seattle, King County, WA

  6. 4. View northwest. South elevation Walpole span, link span, ...

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

    4. View northwest. South elevation - Walpole span, link span, and Westminster span. Structure on east pier is stream level gauge station. - Walpole-Westminster Bridge, Spanning Connecticut River between Walpole, NH & Westminster, VT, Walpole, Cheshire County, NH

  7. Report on orbital debris

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The success of space endeavors depends upon a space environment sufficiently free of debris to enable the safe and dependable operation of spacecraft. An environment overly cluttered with debris would threaten the ability to utilize space for a wide variety of scientific, technological, military, and commercial purposes. Man made space debris (orbital debris) differs from natural meteoroids because it remains in earth orbit during its lifetime and is not transient through the space around the Earth. The orbital debris environment is considered. The space environment is described along with sources of orbital debris. The current national space policy is examined, along with ways to minimize debris generation and ways to survive the debris environment. International efforts, legal issues and commercial regulations are also examined.

  8. Turbomachinery debris remover

    DOEpatents

    Krawiec, Donald F.; Kraf, Robert J.; Houser, Robert J.

    1988-01-01

    An apparatus for removing debris from a turbomachine. The apparatus includes housing and remotely operable viewing and grappling mechanisms for the purpose of locating and removing debris lodged between adjacent blades in a turbomachine.

  9. Debris exhaust system

    DOEpatents

    McBride, Donald D.; Bua, Dominic; Domankevitz, Yacov; Nishioka, Norman

    1998-01-01

    A debris removal system removes debris from a work site by flowing fluid away from the work site toward the periphery of a structure. The fluid flow can be kept constant around the periphery so that debris is removed evenly. The structure can have a reduced cross section between the fluid inlet and the work site so that the resulting increased fluid velocity works to prevent debris from escaping.

  10. Debris exhaust system

    DOEpatents

    McBride, D.D.; Bua, D.; Domankevitz, Y.; Nishioka, N.

    1998-06-23

    A debris removal system removes debris from a work site by flowing fluid away from the work site toward the periphery of a structure. The fluid flow can be kept constant around the periphery so that debris is removed evenly. The structure can have a reduced cross section between the fluid inlet and the work site so that the resulting increased fluid velocity works to prevent debris from escaping. 9 figs.

  11. A replicated record of multi-centennial climate variability in the northern Gulf of Mexico spanning the last 4.4 kyrs from paired δ18O and Mg/Ca in G. ruber

    NASA Astrophysics Data System (ADS)

    Thirumalai, K.; Quinn, T. M.; Reynolds, C.; Richey, J. N.

    2013-12-01

    Sea-surface temperatures (SST) in the Gulf of Mexico (GOM) are an important influence on the moisture budget of the Western Hemisphere and play a key role in tropical to extra-tropical heat transport in the region. Changes in the hydroclimate of the GOM region also influence sea-surface salinity (SSS). Marine sediment records from the Pigmy Basin suggest significant SST variability in the northern GOM over the last two millennia. Some, but not all of this SST variability is also observed in paleoclimate records from the Caribbean-GOM region. To assess the spatial coherency of a regional SST signal, we present marine sediment records from another GOM basin, Garrison Basin (26°43'N, 93°55'W), which is located ~250 km west of Pigmy Basin. We generated time series of paired Mg/Ca (SST proxy) and δ18O (SST and SSS proxy) variations in planktic foraminifer Globigerinoides ruber (white variety) from three multi-cores collected in 2010. A radiocarbon-based chronology indicates that these cores span the last 4400 calendar yrs BP. Initial stable isotopic results reveal excellent replication between the multi-cores and indicate coherent, multi-centennial variability in foraminiferal δ18O. Preliminary Mg/Ca-SST results from one of the cores compare well with published results from the Pigmy Basin. Our replicated results in tandem with a Mg/Ca-δ18O calibration study from a sediment trap located ~350 km east of the Garrison Basin lend confidence that downcore geochemical variations in this region are a robust record of paleoclimate variability.

  12. Space Shuttle Systems Engineering Processes for Liftoff Debris Risk Mitigation

    NASA Technical Reports Server (NTRS)

    Mitchell, Michael; Riley, Christopher

    2011-01-01

    This slide presentation reviews the systems engineering process designed to reduce the risk from debris during Space Shuttle Launching. This process begins the day of launch from the tanking to the vehicle tower clearance. Other debris risks (i.e., Ascent, and micrometeoroid orbital debit) are mentioned) but are not the subject of this presentation. The Liftoff debris systems engineering process and an example of how it works are reviewed (i.e.,STS-119 revealed a bolt liberation trend on the Fixed Service Structure (FSS) 275 level elevator room). The process includes preparation of a Certification of Flight Readiness (CoFR) that includes (1) Lift-off debris from previous mission dispositioned, (2) Flight acceptance rationale has been provided for Lift-off debris sources/causes (3) Lift-off debris mission support documentation, processes and tools are in place for the up-coming mission. The process includes a liftoff debris data collection that occurs after each launch. This includes a post launch walkdown, that records each liftoff debris, and the entry of the debris into a database, it also includes a review of the imagery from the launch, and a review of the instrumentation data. There is also a review of the debris transport analysis process, that includes temporal and spatial framework and a computational fluid dynamics (CFD) analysis. which incorporates a debris transport analyses (DTA), debris materials and impact tests, and impact analyses.

  13. January | 201span>6 | Space Station - NASA

    NASA Website

    August 201span>6; July 201span>6; June 201span>6; May 201span>6; April 201span>6; March 201span>6; February 201span>6; January 201span>6; December 2015; November 2015; October 2015; ...

  14. Organic biomarker records spanning the last 34,800 years from the southeastern Brazilian upper slope: links between sea surface temperature, displacement of the Brazil Current, and marine productivity

    NASA Astrophysics Data System (ADS)

    Lourenço, Rafael André; de Mahiques, Michel Michaelovitch; Wainer, Ilana Elazari Klein Coaracy; Rosell-Melé, Antoni; Bícego, Márcia Caruso

    2016-10-01

    Collective assessment of marine and terrigenous organic biomarkers was performed on a sediment core spanning the last 34,800 years on the upper slope southeast of Brazil to verify the signatures of climatic variations in sea surface temperature (SST), marine productivity, and the flux of terrigenous material in this region. This evaluation is based on marine and terrigenous proxies including alkenones, chlorins, aliphatic hydrocarbons, n-alcohols, and fatty acids. This first report of organic biomarker data for this region confirms a correlation between SST, changes in terrigenous organic matter flow into the ocean, and marine productivity over the last 34.8 ka as a response to the displacement of the Brazil Current. Conditions prevailing during marine isotopic stage (MIS) 3 may be considered intermediate between the last glacial maximum (LGM) and the Late Holocene. For MIS 2, a period of low relative sea level, it was verified that the lowest SSTs were associated with the LGM and higher marine productivity. SST increased by up to 4.4 °C between the LGM and the Holocene. This reveals synchronicity between SST on the southeastern Brazilian upper slope and the North Atlantic Ocean SST records reported in earlier studies.

  15. View of approach span and movable span, looking southeast from ...

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

    View of approach span and movable span, looking southeast from navy land. Note that navigational channel exists only on north side of movable span. - Naval Supply Annex Stockton, Rough & Ready Island, Stockton, San Joaquin County, CA

  16. 4. From Skew Span to portal on span 1 looking ...

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

    4. From Skew Span to portal on span 1 looking up grade toward the south end. - Monongahela Connecting Railroad Company, Hot Metal Bridge, Spanning Monongahela River at mile post 3.1, Pittsburgh, Allegheny County, PA

  17. GENERAL AERIAL VIEW OF WEST CHANNEL SPANS, SPANS 3, 4 ...

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

    GENERAL AERIAL VIEW OF WEST CHANNEL SPANS, SPANS 3, 4 AND 5 REMOVED, LOOKING EAST. - Walnut Street Bridge, Spanning Susquehanna River at Walnut Street (State Route 3034), Harrisburg, Dauphin County, PA

  18. Truncated span west of verticallift span, from SW. Pennsylvania ...

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

    Truncated span west of vertical-lift span, from SW. - Pennsylvania & New Jersey Railroad, Delaware River Bridge, Spanning Delaware River, south of Betsy Ross Bridge (State Route 90), Philadelphia, Philadelphia County, PA

  19. EAST END FROM MID SPAN OF EASTERN SPAN (THREE DIFFERENT ...

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

    EAST END FROM MID SPAN OF EASTERN SPAN (THREE DIFFERENT TRUSSES, EAST SOUTHEAST 110 DEGREES) - Honey Run Bridge, Spanning Butte Creek, bypassed section of Honey Run Road (originally Carr Hill Road), Paradise, Butte County, CA

  20. Observations of space debris

    NASA Technical Reports Server (NTRS)

    Taff, L. G.

    1991-01-01

    Optical observations of near Earth and deep-space debris conducted at M.I.T.'s artificial satellite observatory will be discussed. A brief review of observing technique, regions of high debris density, and amount of debris in orbit will be given. The unique, duplex facilities of the observatory allow the discrimination of debris from meteors, the construction of an orbital element set, and real-time identification of catalogued artificial satellites. Near-Earth debris is present in large numbers in all the popular near-Earth orbits; at least 5-6 times the 5000-6000 objects in the NORAD catalog. In deep-space, the new presence of Ariane-related debris adds significantly to the existing population which is treble that catalogued by NORAD.

  1. Optical orbital debris spotter

    NASA Astrophysics Data System (ADS)

    Englert, Christoph R.; Bays, J. Timothy; Marr, Kenneth D.; Brown, Charles M.; Nicholas, Andrew C.; Finne, Theodore T.

    2014-11-01

    The number of man-made debris objects orbiting the Earth, or orbital debris, is alarmingly increasing, resulting in the increased probability of degradation, damage, or destruction of operating spacecraft. In part, small objects (<10 cm) in Low Earth Orbit (LEO) are of concern because they are abundant and difficult to track or even to detect on a routine basis. Due to the increasing debris population it is reasonable to assume that improved capabilities for on-orbit damage attribution, in addition to increased capabilities to detect and track small objects are needed. Here we present a sensor concept to detect small debris with sizes between approximately 1.0 and 0.01 cm in the vicinity of a host spacecraft for near real time damage attribution and characterization of dense debris fields and potentially to provide additional data to existing debris models.

  2. Space debris detection and mitigation

    SciTech Connect

    Allahdadi, F.

    1993-01-01

    Space debris is defined as all useless man-made objects in space. This conference covers the following areas: debris detection, tracking, and surveillance; orbital debris analytical modeling; debris environment and safety issues; and orbital debris mitigation. Separate abstracts were prepared for 26 papers in this conference.

  3. What is SPAN?

    NASA Astrophysics Data System (ADS)

    SPAN is the Space Physics Analysis Network. This important research tool of the NASA scientific community links space researchers from over 50 institutions throughout the United States. The SPAN system is growing within the United States, and it also is expanding to connect NASA scientists with European and Japanese space research institutions.The SPAN system serves many functions. Its paramount purpose is to provide scientists with a tool that improves their productivity. SPAN has traditionally been used to exchange mail messages, to send data back and forth for scientific papers and analysis workshops, and to share scientific software. SPAN has played a crucial role by disseminating spacecraft data in near-real time during several recent NASA and ESA program successes, such as the International Cometary Explorer (ICE) spacecraft encounter with Comet Giacobini-Zinner (see “Behind the Scenes During a Comet Encounter” by J.L. Green and J.H. King, Eos, March 4, 1986, p. 105), the Voyager 2 encounter with Uranus, and the Giotto spacecraft encounter with Comet Halley (see “Networking Ground-Based Images of Comet Halley during the Giotto Encounter” by D. Rees et al., Eos, December 16, 1986, p. 1385). Of course, SPAN has served a variety of broader purposes. It has provided (and will continue to provide) an excellent testing ground for trying new technologies and for evaluating ideas about processing, storing, and transferring various kinds of information. Until the recent availability of computers sponsored by the National Science Foundation, the SPAN network provided one of the few opportunities for NASA researchers to have ready access to the supercomputers needed for large-scale numerical simulation of magnetospheric and ionospheric plasma systems. SPAN has also increased its usefulness substantially by the addition of the National Space Science Data Center (NSSDC) as a data node on the system. The network, which was originally based on a starshaped

  4. Origin of marine debris is related to disposable packs of ultra-processed food.

    PubMed

    Andrades, Ryan; Martins, Agnaldo S; Fardim, Lorena M; Ferreira, Juliana S; Santos, Robson G

    2016-08-15

    Marine debris is currently distributed worldwide, and the discard and contamination pose hazards to human and wildlife health. One of the gaps in debris science is tracking the source of debris to better evaluate and avoid the pathway of debris from the source to marine environment. For this, we evaluated three beaches of different urbanization levels and environmental influences; a low urbanized beach, a highly urbanized beach and a non-urbanized estuary-associated beach, in order to determine the sources and original use of debris. Plastic was the major material found on beaches, and the urbanized beach recorded the highest debris densities. Marine debris was primarily from land-based sources, and the debris recorded in all beaches was mainly assigned as food-related items. Our results highlight the major presence of disposable and short-lived products comprising the majority of debris that enters the ocean and draw attention to the unsustainable lifestyle of current society.

  5. Geophysical features influence the accumulation of beach debris on Caribbean islands.

    PubMed

    Schmuck, Alexandra M; Lavers, Jennifer L; Stuckenbrock, Silke; Sharp, Paul B; Bond, Alexander L

    2017-08-15

    Anthropogenic beach debris was recorded during beach surveys of 24 Caribbean islands during April 2014-April 2016. Beach debris was classified according to material type (e.g., polystyrene) and item use (e.g., fishing). Geophysical features (substrate type, beach direction, and human accessibility) of sample sites were recorded in order to investigate their relationship with debris density. Results suggest the density of macro debris (items >5mm) is highest on uninhabited, sandy beaches facing a leeward direction. Higher debris quantities on inaccessible beaches may be due to less frequent beach clean ups. Frequently accessed beaches exhibited lower macro, but higher micro debris (items 1-5mm) densities, possibly due to removal of macro debris during frequent beach clean ups. This suggests that while geophysical features have some influence on anthropogenic debris densities, high debris densities are occurring on all islands within the Caribbean region regardless of substrate, beach direction, or human accessibility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Debris Disks: An Overview

    NASA Astrophysics Data System (ADS)

    Backman, D.

    2004-12-01

    An overview regarding planetary debris disks: First, more history to complement Low and Aumann's summary appearing elsewhere in this volume. Then, commentary on the nature of debris disks and what we've learned from them: properties of the original ``Fabulous Four" archetypes, results from surveys showing that a large fraction of ordinary stars may be hosts for debris disks, and relatively detailed discussion of β Pictoris, the most prominent disk. Finally, discussion of the connection between debris disks, our solar system's Kuiper Belt, and the zodiacal dust cloud. Open questions about these objects will be highlighted which can lead on to the remainder of the proceedings.

  7. Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Burns, Susan H.

    2012-01-01

    Orbital debris in Low Earth Orbit (LEO) is an international problem that threatens the success of future space ventures. An analysis of a wide variety of alternative solutions for active debris removal (ADR) has been performed. The solution selected is an efficient, effective, and executable solution to remove large debris in LEO, primarily spent rocket bodies. Removing large debris objects is a critical step in reducing the hazard from orbital debris, because of the large amount of medium and small debris created through large body collisions. Based on the analysis of alternatives, the concept and design for a vehicle which could efficiently address the debris hazard by disposing of several large objects per mission has been developed. This concept establishes a comprehensive, detailed technical approach for an actual end-to-end, on-orbit ADR solution to remove large debris. This robust solution enables the start of solving the problem of debris removal before it reaches a critical and potentially irreversible state by "getting there as soon as possible, as economically as possible, with the most capability".

  8. Orbital debris issues

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.

    1985-01-01

    Man-made orbital debris, identified as a potential hazard to future space activities, is grouped into size categories. At least 79 satellites have broken up in orbit to date and, in combination with exploded rocket casings and antisatellite debris, threaten 10 km/sec collisions with other orbiting platforms. Only 5 percent of the debris is connected to payloads. The total population of orbiting objects over 4 cm in diameter could number as high as 15,000, and at 1 cm in diameter could be 32,000, based on NASA and NORAD studies. NASA has initiated the 10 yr Space Debris Assessment Program to characterize the hazards of orbiting debris, the potential damage to typical spacecraft components, and to identify means of controlling the damage.

  9. Orbital Debris Mitigation

    NASA Technical Reports Server (NTRS)

    Kelley, R. L.; Jarkey, D. R.; Stansbery, G.

    2014-01-01

    Policies on limiting orbital debris are found throughout the US Government, many foreign space agencies, and as adopted guidelines in the United Nations. The underlying purpose of these policies is to ensure the environment remains safe for the operation of robotic and human spacecraft in near- Earth orbit. For this reason, it is important to consider orbital debris mitigation during the design of all space vehicles. Documenting compliance with the debris mitigation guidelines occurs after the vehicle has already been designed and fabricated for many CubeSats, whereas larger satellites are evaluated throughout the design process. This paper will provide a brief explanation of the US Government Orbital Debris Mitigation Standard Practices, a discussion of international guidelines, as well as NASA's process for compliance evaluation. In addition, it will discuss the educational value of considering orbital debris mitigation requirements as a part of student built satellite design.

  10. Gear Damage Detection Using Oil Debris Analysis

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.

    2001-01-01

    The purpose of this paper was to verify, when using an oil debris sensor, that accumulated mass predicts gear pitting damage and to identify a method to set threshold limits for damaged gears. Oil debris data was collected from 8 experiments with no damage and 8 with pitting damage in the NASA Glenn Spur Gear Fatigue Rig. Oil debris feature analysis was performed on this data. Video images of damage progression were also collected from 6 of the experiments with pitting damage. During each test, data from an oil debris sensor was monitored and recorded for the occurrence of pitting damage. The data measured from the oil debris sensor during experiments with damage and with no damage was used to identify membership functions to build a simple fuzzy logic model. Using fuzzy logic techniques and the oil debris data, threshold limits were defined that discriminate between stages of pitting wear. Results indicate accumulated mass combined with fuzzy logic analysis techniques is a good predictor of pitting damage on spur gears.

  11. Span efficiency in hawkmoths.

    PubMed

    Henningsson, Per; Bomphrey, Richard J

    2013-07-06

    Flight in animals is the result of aerodynamic forces generated as flight muscles drive the wings through air. Aerial performance is therefore limited by the efficiency with which momentum is imparted to the air, a property that can be measured using modern techniques. We measured the induced flow fields around six hawkmoth species flying tethered in a wind tunnel to assess span efficiency, ei, and from these measurements, determined the morphological and kinematic characters that predict efficient flight. The species were selected to represent a range in wingspan from 40 to 110 mm (2.75 times) and in mass from 0.2 to 1.5 g (7.5 times) but they were similar in their overall shape and their ecology. From high spatio-temporal resolution quantitative wake images, we extracted time-resolved downwash distributions behind the hawkmoths, calculating instantaneous values of ei throughout the wingbeat cycle as well as multi-wingbeat averages. Span efficiency correlated positively with normalized lift and negatively with advance ratio. Average span efficiencies for the moths ranged from 0.31 to 0.60 showing that the standard generic value of 0.83 used in previous studies of animal flight is not a suitable approximation of aerodynamic performance in insects.

  12. Span efficiency in hawkmoths

    PubMed Central

    Henningsson, Per; Bomphrey, Richard J.

    2013-01-01

    Flight in animals is the result of aerodynamic forces generated as flight muscles drive the wings through air. Aerial performance is therefore limited by the efficiency with which momentum is imparted to the air, a property that can be measured using modern techniques. We measured the induced flow fields around six hawkmoth species flying tethered in a wind tunnel to assess span efficiency, ei, and from these measurements, determined the morphological and kinematic characters that predict efficient flight. The species were selected to represent a range in wingspan from 40 to 110 mm (2.75 times) and in mass from 0.2 to 1.5 g (7.5 times) but they were similar in their overall shape and their ecology. From high spatio-temporal resolution quantitative wake images, we extracted time-resolved downwash distributions behind the hawkmoths, calculating instantaneous values of ei throughout the wingbeat cycle as well as multi-wingbeat averages. Span efficiency correlated positively with normalized lift and negatively with advance ratio. Average span efficiencies for the moths ranged from 0.31 to 0.60 showing that the standard generic value of 0.83 used in previous studies of animal flight is not a suitable approximation of aerodynamic performance in insects. PMID:23658113

  13. Dependence of debris cloud formation on projectile shape

    NASA Astrophysics Data System (ADS)

    Konrad, C. H.; Chhabildas, L. C.; Boslough, M. B.; Piekutowski, A. J.; Poormon, K. L.; Mullin, S. A.; Littlefield, D. L.

    1994-07-01

    A two-stage lights-gas gun has been used to impact thin zinc bumpers by zinc projectiles over the velocity range of 2.4 km/s to 6.7 km/s to determine the propagation characteristics of the impact generated debris. Constant-mass projectiles in the form of spheres, discs, cylinders, and rods were used in these studies. Radiographic techniques were employed to record the debris cloud generated upon impact and the dynamic formation of the resulting rupture in an aluminum backing plate resulting from the loading of the debris cloud. The characteristics of the debris cloud generated upon impact is found to depend on the projectile shape. The data indicate that the debris front velocity is independent of the shape of the projectile, whereas the debris lateral/radial velocity is strongly dependent on projectile geometry. Spherical impactors generate the most radially dispersed debris cloud while the normal plate impactors result in column-like debris. It has been observed that the debris generated by the impact of thin plates on a thin bumper shield is considerably more damaging to a backwall than the debris generated by an equivalent-mass sphere.

  14. Debris flow, debris avalanche and flood hazards at and downstream from Mount Rainier, Washington

    USGS Publications Warehouse

    Scott, Kevin M.; Vallance, J.W.

    1995-01-01

    Mount Rainier volcano has produced many large debris flows and debris avalanches during the last 10,000 years. These flows have periodically traveled more than 100 kilometers from the volcano to inundate parts of the now-populated Puget Sound Lowland. Meteorological floods also have caused damage, but future effects will be partly mitigated by reservoirs. Mount Rainier presents the most severe flow risks of any volcano in the United States. Volcanic debris flows (lahars) are of two types: (1) cohesive, relatively high clay flows originating as debris avalanches, and (2) noncohesive flows with less clay that begin most commonly as meltwater surges. Three case histories represent important subpopulations of flows with known magnitudes and frequencies. The risks of each subpopulation may be considered for general planning and design. A regional map illustrates the extent of inundation by the case-history flows, the largest of which originated as debris avalanches and moved from Mount Rainier to Puget Sound. The paleohydrologic record of these past flows indicates the potential for inundation by future flows from the volcano. A map of the volcano and its immediate vicinity shows examples of smaller debris avalanches and debris flows in the 20th century.

  15. Effect of perturbations on debris-to-debris orbital transfers: A quantitative analysis

    NASA Astrophysics Data System (ADS)

    Kumar, Kartik; Hekma, Enne; Agrawal, Abhishek; Topputo, Francesco

    2017-03-01

    We investigated the applicability of the Lambert solver (Izzo, 2014) for preliminary design of Multi-Target Active Debris Removal missions. Firstly, we computed ≈25 million debris-to-debris transfers using the Lambert solver for selected sets of debris objects in Low Earth Orbit, Geostationary Transfer Orbit, and Geosynchronous Orbit. Subsequently, we propagated the departure states of the Lambert transfers below selected ΔV cut-offs using the SGP4/SDP4 propagator (Vallado et al., 2006). We recorded the arrival position and velocity error vectors incurred by neglecting perturbations and analyzed the results for each orbital regime. Our results indicate that perturbations can play a significant role in determining the feasibility of debris-to-debris transfers. By using the Lambert solver and neglecting perturbations, the errors in the arrival position and velocity for individual legs can be large. The largest errors were obtained for transfers between debris objects in Sun-Synchronous Orbit (O (100) km error in magnitude of position vector and O (0.1) km/s error in magnitude of velocity vector). Hence, solely employing the Lambert solver to rank transfer legs could lead to incorrect choices for sequencing of multi-target trajectories. This is particularly relevant for transfers in Low Earth Orbit, where the effects of perturbations are the strongest.

  16. Sources, composition and spatial distribution of marine debris along the Mediterranean coast of Israel.

    PubMed

    Pasternak, Galia; Zviely, Dov; Ribic, Christine A; Ariel, Asaf; Spanier, Ehud

    2017-01-30

    Marine debris (litter) is a complex problem that affects human activities and the marine environment worldwide. The Clean Coast Program in Israel has had some success in keeping most of the coasts clean most of the time, but without understanding the mechanisms of accumulation of marine debris on the coasts of Israel. In 2012, we initiated a study to characterize the types of marine debris, its origins and spatial distribution. Nineteen surveys were done from June 2012 to March 2015 on eight beaches that spanned the coast of Israel. Average debris density was 12.1 items per 100m(2) and 90% of the items were plastic. The top debris categories were food wrappers and disposables, plastic bags and cigarette butts. However, there was variation in the top debris categories among the beaches indicating that a flexible approach with multiple options will be important when addressing the marine debris problem. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Sources, composition and spatial distribution of marine debris along the Mediterranean coast of Israel

    USGS Publications Warehouse

    Pasternak, Galia; Zviely, Dov; Ribic, Christine; Ariel, Asaf; Spanier, Ehud

    2017-01-01

    Marine debris (litter) is a complex problem that affects human activities and the marine environment worldwide. The Clean Coast Program in Israel has had some success in keeping most of the coasts clean most of the time, but without understanding the mechanisms of accumulation of marine debris on the coasts of Israel. In 2012, we initiated a study to characterize the types of marine debris, its origins and spatial distribution. Nineteen surveys were done from June 2012 to March 2015 on eight beaches that spanned the coast of Israel. Average debris density was 12.1 items per 100 m2 and 90% of the items were plastic. The top debris categories were food wrappers and disposables, plastic bags and cigarette butts. However, there was variation in the top debris categories among the beaches indicating that a flexible approach with multiple options will be important when addressing the marine debris problem.

  18. Current orbital debris environment

    NASA Technical Reports Server (NTRS)

    Kessler, Donald J.

    1989-01-01

    NASA has instituted a plan for the definition of activities and resources required over the coming decade for the deepening of current understanding of anthropogenic orbital debris, and its effects on future mission operations. This understanding will be the basis of policy definition and policy implementation efforts. The most immediate requirement is the definition of the debris environment, with emphasis on data for debris sizes smaller than 4 cm. Systems-damage criteria and hypervelocity-impact theory will then be used to define the hazard to specific spacecraft.

  19. SPECS: Orbital debris removal

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The debris problem has reached a stage at which the risk to satellites and spacecraft has become substantial in low Earth orbit (LEO). This research discovered that small particles posed little threat to spacecraft because shielding can effectively prevent these particles from damaging the spacecraft. The research also showed that, even though collision with a large piece of debris could destroy the spacecraft, the large pieces of debris pose little danger because they can be tracked and the spacecraft can be maneuvered away from these pieces. Additionally, there are many current designs to capture and remove large debris particles from the space environment. From this analysis, it was decided to concentrate on the removal of medium-sized orbital debris, that is, those pieces ranging from 1 cm to 50 cm in size. The current design incorporates a transfer vehicle and a netting vehicle to capture the medium-sized debris. The system is based near an operational space station located at 28.5 deg inclination and 400 km altitude. The system uses ground-based tracking to determine the location of a satellite breakup or debris cloud. These data are uploaded to the transfer vehicle, which proceeds to rendezvous with the debris at a lower altitude parking orbit. Next, the netting vehicle is deployed, tracks the targeted debris, and captures it. After expending the available nets, the netting vehicle returns to the transfer vehicle for a new netting module and continues to capture more debris in the target area. Once all the netting modules are expended, the transfer vehicle returns to the space station's orbit where it is resupplied with new netting modules from a space shuttle load. The new modules are launched by the shuttle from the ground and the expended modules are taken back to Earth for removal of the captured debris, refueling, and repacking of the nets. Once the netting modules are refurbished, they are taken back into orbit for reuse. In a typical mission, the

  20. Characterizing the Space Debris Environment with a Variety of SSA Sensors

    NASA Technical Reports Server (NTRS)

    Stansbery, Eugene G.

    2010-01-01

    Damaging space debris spans a wide range of sizes and altitudes. Therefore no single method or sensor can fully characterize the space debris environment. Space debris researchers use a variety of radars and optical telescopes to characterize the space debris environment in terms of number, altitude, and inclination distributions. Some sensors, such as phased array radars, are designed to search a large volume of the sky and can be instrumental in detecting new breakups and cataloging and precise tracking of relatively large debris. For smaller debris sizes more sensitivity is needed which can be provided, in part, by large antenna gains. Larger antenna gains, however, produce smaller fields of view. Statistical measurements of the debris environment with less precise orbital parameters result. At higher altitudes, optical telescopes become the more sensitive instrument and present their own measurement difficulties. Space Situational Awareness, or SSA, is concerned with more than the number and orbits of satellites. SSA also seeks to understand such parameters as the function, shape, and composition of operational satellites. Similarly, debris researchers are seeking to characterize similar parameters for space debris to improve our knowledge of the risks debris poses to operational satellites as well as determine sources of debris for future mitigation. This paper will discuss different sensor and sensor types and the role that each plays in fully characterizing the space debris environment.

  1. Characterizing the Space Debris Environment with a Variety of SSA Sensors

    NASA Astrophysics Data System (ADS)

    Stansbery, Eugene

    Damaging space debris spans a wide range of sizes and altitudes. Therefore no single method or sensor can fully characterize the space debris environment. Space debris researchers use a variety of radars and optical telescopes to characterize the space debris environment in terms of number, altitude, and inclination distributions. Some sensors, such as phased array radars, are designed to search a large volume of the sky and can be instrumental in detecting new breakups and cataloging and precise tracking of relatively large debris. For smaller debris sizes more sensitivity is needed which can be provided, in part, by large antenna gains. Larger antenna gains, however, produce smaller fields of view. Statistical measurements of the debris environment with less precise orbital parameters result. At higher altitudes, optical telescopes become the more sensitive instrument and present their own measurement difficulties. Space Situational Awareness, or SSA, is concerned with more than the number and orbits of satellites. SSA also seeks to understand such parameters as the function, shape, and compo-sition of operational satellites. Similarly, debris researchers are seeking to characterize similar parameters for space debris to improve our knowledge of the risks debris poses to operational satellites as well as determine sources of debris for future mitigation. This paper will discuss different sensor and sensor types and the role that each plays in fully characterizing the space debris environment.

  2. Orbital debris: A technical assessment

    NASA Technical Reports Server (NTRS)

    Gleghorn, George; Asay, James; Atkinson, Dale; Flury, Walter; Johnson, Nicholas; Kessler, Donald; Knowles, Stephen; Rex, Dietrich; Toda, Susumu; Veniaminov, Stanislav

    1995-01-01

    To acquire an unbiased technical assessment of (1) the research needed to better understand the debris environment, (2) the necessity and means of protecting spacecraft against the debris environment, and (3) potential methods of reducing the future debris hazard, NASA asked the National Research Council to form an international committee to examine the orbital debris issue. The committee was asked to draw upon available data and analyses to: characterize the current debris environment, project how this environment might change in the absence of new measures to alleviate debris proliferation, examine ongoing alleviation activities, explore measures to address the problem, and develop recommendations on technical methods to address the problems of debris proliferation.

  3. 16. Overall view of the swing span (Span G) turning ...

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

    16. Overall view of the swing span (Span G) turning drum, showing rollers and drive chains; looking W. (Ceronie) - Rock Island Arsenal, Rock Island Bridge, Fort Armstrong Avenue, Rock Island, Rock Island County, IL

  4. Disposal of Cleaning Debris

    DTIC Science & Technology

    1976-04-01

    trees. In addition, the debris contains some plastic bottles , balls, rubber items, and glass . The wood debris is in various stages of...the upper portion, which contains vegetation falls into the river. Plastic bottles and various other discarded objects periodically float into the...the reservoir includes tree stumps, tree branches, tree trunks, tires, oil drums, plastic bottles , signs from recreational areas in the White

  5. Orbital Debris Modeling

    NASA Technical Reports Server (NTRS)

    Liou, J. C.

    2012-01-01

    Presentation outlne: (1) The NASA Orbital Debris (OD) Engineering Model -- A mathematical model capable of predicting OD impact risks for the ISS and other critical space assets (2) The NASA OD Evolutionary Model -- A physical model capable of predicting future debris environment based on user-specified scenarios (3) The NASA Standard Satellite Breakup Model -- A model describing the outcome of a satellite breakup (explosion or collision)

  6. Albedo estimates for debris

    NASA Technical Reports Server (NTRS)

    Potter, A. E.; Henize, Karl G.; Talent, D. L.

    1989-01-01

    The albedo of upper-stage breakup debris is proposed as an accurate discriminator among the various possible causes of breakup, which encompass residual fuel explosions and hypervelocity particle impacts. The fragments from an impact are covered with a thin layer of soot deposited from the destruction of polymeric circuit boards, while pressure vessel explosion fragments can be expected to remain soot-free. Albedo also facilitates the interpretation of small-debris optical telescope measurements.

  7. View of approach span and movable span, looking southeast from ...

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

    View of approach span and movable span, looking southeast from navy land. Note that navigational channel exists only on north side of movable span. - Naval Supply Annex Stockton, Daggett Road Bridge, Daggett Road traversing Burns Cut Off, Stockton, San Joaquin County, CA

  8. Shielding against debris

    NASA Technical Reports Server (NTRS)

    Cour-Palais, Burton G.; Avans, Sherman L.

    1988-01-01

    The damage to spacecraft caused by debris and design of the Space Station to minimize damage from debris are discussed. Although current estimates of the debris environment show that fragments bigger than 2 cm are not likely to hit the Space Station, orbital debris from about 0.5 mm to 2 cm will pose a hazard, especially on brittle surfaces, such as glass. Spacesuits are being designed to reduce debris caused dangers to astronauts during EVA. About 5 cm of high-strength aluminum are needed to prevent penetration by a 1 cm piece of aluminum with a mass near 1.5 g colliding at 10 km/sec. Because aluminum bumpers have the drawback of metallic debris ejected outward after a hypervelocity collision, the use of nonmetallic materials for bumpers is being studied. Methods of reducing the weight and volume of the shield for the Space Station are also being researched. A space station habitation module using bumpers has a 99.6 percent chance of avoiding penetration during its lifetime.

  9. Characterization of Debris from the DebriSat Hypervelocity Test

    NASA Technical Reports Server (NTRS)

    Rivero, M.; Kleespies, J.; Patankar, K.; Fitz-Coy, N.; Liou, J.-C.; Sorge, M.; Huynh, T.; Opiela, J.; Krisko, P.; Cowardin, H.

    2015-01-01

    The DebriSat project is an effort by NASA and the DoD to update the standard break-up model for objects in orbit. The DebriSat object, a 56 kg representative LEO satellite, was subjected to a hypervelocity impact in April 2014. For the hypervelocity test, the representative satellite was suspended within a "soft-catch" arena formed by polyurethane foam panels to minimize the interactions between the debris generated from the hypervelocity impact and the metallic walls of the test chamber. After the impact, the foam panels and debris not caught by the panels were collected and shipped to the University of Florida where the project has now advanced to the debris characterization stage. The characterization effort has been divided into debris collection, measurement, and cataloguing. Debris collection and cataloguing involves the retrieval of debris from the foam panels and cataloguing the debris in a database. Debris collection is a three-step process: removal of loose debris fragments from the surface of the foam panels; X-ray imaging to identify/locate debris fragments embedded within the foam panel; extraction of the embedded debris fragments identified during the X-ray imaging process. As debris fragments are collected, they are catalogued into a database specifically designed for this project. Measurement involves determination of size, mass, shape, material, and other physical properties and well as images of the fragment. Cataloguing involves a assigning a unique identifier for each fragment along with the characterization information.

  10. Marine debris in harbour porpoises and seals from German waters.

    PubMed

    Unger, B; Herr, H; Benke, H; Böhmert, M; Burkhardt-Holm, P; Dähne, M; Hillmann, M; Wolff-Schmidt, K; Wohlsein, P; Siebert, U

    2017-09-01

    Records of marine debris in and attached to stranded harbour porpoises (Phocoena phocoena), harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) were studied comprising information on 6587 carcasses collected along the German coast between 1990 and 2014, the decomposition state allowed for necropsy in 1622 cases. Marine debris items were recorded in 31 carcasses including 14 entanglements (5 harbour porpoises, 6 harbour seals, 3 grey seals) and 17 cases of ingestion (4 harbour porpoises, 10 harbour seals, 3 grey seals). Objects comprised general debris (35.1%) and fishing related debris (64.9%). Injuries associated with marine debris included lesions, suppurative ulcerative dermatitis, perforation of the digestive tract, abscessation, suppurative peritonitis and septicaemia. This study is the first investigation of marine debris findings in all three marine mammal species from German waters. It demonstrates the health impacts marine debris can have, including severe suffering and death. The results provide needed information on debris burdens in the North and Baltic Seas for implementing management directives, such as the Marine Strategy Framework Directive (MSFD). Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Atmospheric Rivers as a Trigger for Landslides and Post-Fire Debris Flows in Southern California

    NASA Astrophysics Data System (ADS)

    Oakley, N.; Lancaster, J.; Stock, J. D.; Cerovski-Darriau, C.; Kaplan, M.; Ralph, F. M.

    2016-12-01

    Episodic storms strike the steeplands of Southern California, triggering shallow landslides and post-wildfire debris flows. These hazards have killed and injured people and destroyed property and infrastructure, in some cases with little warning. In the absence of more evolved monitoring networks, the National Weather Service, working with USGS, has proposed rainfall intensity-duration threshold values to forecast the risk of such mass-wasting events. Absent from this procedure, however, is an understanding of what kinds of storms have exceeded these thresholds and generated historic mass-wasting events. With the goal of testing what atmospheric conditions are associated with historic mass wasting episodes, we explored the instrumental record for mass-wasting events spanning several decades. We summarized meteorological conditions for 19 storm events associated with post-wildfire debris flows and 24 storm events associated with shallow landslides. In these catalogs, we found that 74% of post-wildfire debris flow events and 75% of shallow landslide events occurred during atmospheric river (AR) conditions. ARs are narrow corridors of high water vapor transport, typically in the lowest 2-3 km of the atmosphere. Previous work has attributed ARs to many of California's heavy precipitation events. Our analysis shows that AR conditions favor precipitation intensities and durations that trigger landsliding. These results suggest that AR-specific forecasting tools may provide Southern California communities with some level of early warning for widespread landsliding. An improved understanding of AR events can help preparedness and hazard mitigation related to landslides, post-wildfire debris flows, and flooding in southern California.

  12. Space Debris & its Mitigation

    NASA Astrophysics Data System (ADS)

    Kaushal, Sourabh; Arora, Nishant

    2012-07-01

    Space debris has become a growing concern in recent years, since collisions at orbital velocities can be highly damaging to functioning satellites and can also produce even more space debris in the process. Some spacecraft, like the International Space Station, are now armored to deal with this hazard but armor and mitigation measures can be prohibitively costly when trying to protect satellites or human spaceflight vehicles like the shuttle. This paper describes the current orbital debris environment, outline its main sources, and identify mitigation measures to reduce orbital debris growth by controlling these sources. We studied the literature on the topic Space Debris. We have proposed some methods to solve this problem of space debris. We have also highlighted the shortcomings of already proposed methods by space experts and we have proposed some modification in those methods. Some of them can be very effective in the process of mitigation of space debris, but some of them need some modification. Recently proposed methods by space experts are maneuver, shielding of space elevator with the foil, vaporizing or redirecting of space debris back to earth with the help of laser, use of aerogel as a protective layer, construction of large junkyards around international space station, use of electrodynamics tether & the latest method proposed is the use of nano satellites in the clearing of the space debris. Limitations of the already proposed methods are as follows: - Maneuvering can't be the final solution to our problem as it is the act of self-defence. - Shielding can't be done on the parts like solar panels and optical devices. - Vaporizing or redirecting of space debris can affect the human life on earth if it is not done in proper manner. - Aerogel has a threshold limit up to which it can bear (resist) the impact of collision. - Large junkyards can be effective only for large sized debris. In this paper we propose: A. The Use of Nano Tubes by creating a mesh

  13. Benefits of Active Debris Removal on the LEO Debris Population

    NASA Astrophysics Data System (ADS)

    Maniwa, Kazuaki; Hanada, Toshiya; Kawamoto, Satomi

    Since the launch of Sputnik, orbital debris population continues to increase due to ongoing space activities, on-orbit explosions, and accidental collisions. In the future, a great deal of fragments can be expected to be created by explosions and collisions. In spite of prevention of satellite and rocket upper stage explosions and other mitigation measures, debris population in low Earth orbit may not be stabilized. To better limit the growth of the future debris population, it is necessary to remove the existing debris actively. This paper studies about the effectiveness of active debris removal in low Earth orbit where the collision rate with and between space debris is high. This study does not consider economic problems, but investigates removing debris which may stabilize well the current debris population based on the concept of Japan Aerospace Exploration Agency.

  14. Space debris detection

    NASA Astrophysics Data System (ADS)

    Eather, Robert H.

    1992-12-01

    A feasibility study on the possibility of detecting less than or = 10 cm space debris using a large-aperture ground-based telescope (with an intensified CCD detector) was completed, showing that detection should be possible. A detector system was designed and built, and installed on the 2.54 m WRDC telescope at Wright Patterson AFB. Bad seeing conditions in the Dayton area prevented the expected debris detection. Subsequently, a small 40 cm telescope was built and operated from the Haystack Observatory (Groton, MA). Known objects were used to test pointing and acquisition procedures, and the system was then shipped to Rattlesnake Observatory (Richland, WA) for participation in the ODERAC's debris calibration experiment from the Space Shuttle. This experiment failed, and our instrument has been stored at Rattlesnake in anticipation of a new ODERAC's flight in late 1993.

  15. Meteoroid/Debris Shielding

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.

    2003-01-01

    This report provides innovative, low-weight shielding solutions for spacecraft and the ballistic limit equations that define the shield's performance in the meteoroid/debris environment. Analyses and hypervelocity impact testing results are described that have been used in developing the shields and equations. Spacecraft shielding design and operational practices described in this report are used to provide effective spacecraft protection from meteoroid and debris impacts. Specific shield applications for the International Space Station (ISS), Space Shuttle Orbiter and the CONTOUR (Comet Nucleus Tour) space probe are provided. Whipple, Multi-Shock and Stuffed Whipple shield applications are described.

  16. Dendrogeomorphic evidence of debris flow frequency and magnitude at Mount Shasta, California

    NASA Astrophysics Data System (ADS)

    Hupp, C. R.

    1984-06-01

    Debris-flow deposits and woody vegetation adjacent to and growing within the channels of Whitney, Bolam, Mud, Ash, and Panthe creeks provide a 300-year record of debris-flow frequency at Mount Shasta Dendrochronologic (tree-ring) dating methods for the debris flows proved consistent with available documented records of debris flows Nine debris flows not reported in the historic record were documented and dated dendrochronologically. The oldest tree-ring date for a mudflow was about 1670 Combined geomorphic and botanical evidence shows that debris flows are a common occurrence at Mount Shasta Debris flows traveling at least 2 km have occurred at the rate of about 8 3 per century Smaller debris flows occur substantially more frequently and usually do not proceed as far downslope as larger debris flows. Cyclic scouring and filling by debris flows, in and adjacent to the stream channels, is suggested by dendrogeomorphic evidence and appears to be related to their magnitude and frequency Debris flows, small and large, may be the major surficial geomorphic agent in the vicinity of mount Shasta, sculpturing the channels and developing large alluvial fans

  17. Dendrogeomorphic evidence of debris flow frequency and magnitude at Mount Shasta, California

    USGS Publications Warehouse

    Hupp, C.R.

    1984-01-01

    Debris-flow deposits and woody vegetation adjacent to and growing within the channels of Whitney, Bolam, Mud, Ash, and Panthe creeks provide a 300-year record of debris-flow frequency at Mount Shasta Dendrochronologic (tree-ring) dating methods for the debris flows proved consistent with available documented records of debris flows Nine debris flows not reported in the historic record were documented and dated dendrochronologically. The oldest tree-ring date for a mudflow was about 1670 Combined geomorphic and botanical evidence shows that debris flows are a common occurrence at Mount Shasta Debris flows traveling at least 2 km have occurred at the rate of about 8 3 per century Smaller debris flows occur substantially more frequently and usually do not proceed as far downslope as larger debris flows. Cyclic scouring and filling by debris flows, in and adjacent to the stream channels, is suggested by dendrogeomorphic evidence and appears to be related to their magnitude and frequency Debris flows, small and large, may be the major surficial geomorphic agent in the vicinity of mount Shasta, sculpturing the channels and developing large alluvial fans ?? 1984 Springer-Verlag New York Inc.

  18. Orbital Debris: A Policy Perspective

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2007-01-01

    A viewgraph presentation describing orbital debris from a policy perspective is shown. The contents include: 1) Voyage through near-Earth Space-animation; 2) What is Orbital Debris?; 3) Orbital Debris Detectors and Damage Potential; 4) Hubble Space Telescope; 5) Mir Space Station Solar Array; 6) International Space Station; 7) Space Shuttle; 8) Satellite Explosions; 9) Satellite Collisions; 10) NASA Orbital Debris Mitigation Guidelines; 11) International Space Station Jettison Policy; 12) Controlled/Uncontrolled Satellite Reentries; 13) Return of Space Objects; 14) Orbital Debris and U.S. National Space Policy; 15) U.S Government Policy Strategy; 16) Bankruptcy of the Iridium Satellite System; 17) Inter-Agency Space Debris Coordination Committee (IADC); 18) Orbital Debris at the United Nations; 19) Chinese Anti-satellite System; 20) Future Evolution of Satellite Population; and 21) Challenge of Orbital Debris

  19. Space Debris Mitigation Guidelines

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2011-01-01

    The purpose of national and international space debris mitigation guides is to promote the preservation of near-Earth space for applications and exploration missions far into the future. To accomplish this objective, the accumulation of objects, particularly in long-lived orbits, must be eliminated or curtailed.

  20. The response of debris-covered glaciers to climate change: A numerical modeling approach

    NASA Astrophysics Data System (ADS)

    Anderson, Leif S.; Anderson, Robert S.

    2016-04-01

    foundation to interpret the effect of debris cover on the moraine record, and to forecast the likely effects of climate change on debris-covered glaciers.

  1. EISCAT Space Debris during the IPY- A 5000-Hour Campaign

    NASA Astrophysics Data System (ADS)

    Markkanen, J.; Jehn, R.; Krag, H.

    2009-03-01

    During the International Polar Year (IPY) in 2007-2009, EISCAT measured space debris at its Svalbard radar (ESR, latitude 78.2°N), simultaneously with the standard ionospheric measurement. From the 239 000 events which were recorded in 5060 hours only a "Quality Set" (QS) was extracted for further analysis. The QS essentially consists of 101 complete 24-hour beam park debris measurements, between 13 Mar 2007 and 10 Feb 2008, and contains about 95 000 events. The data provide a relatively dense sampling of the debris environment above ESR in the first year following the Chinese ASAT event, in January 2007. The QS is freely available in the web.

  2. First Sentinel-1 detections of avalanche debris

    NASA Astrophysics Data System (ADS)

    Malnes, E.; Eckerstorfer, M.; Vickers, H.

    2015-03-01

    Snow avalanches are natural hazards, occurring in snow covered mountain terrain worldwide. Present avalanche research and forecasting relies on complete avalanche activity records in a given area over an entire winter season, which cannot be provided with traditional, mainly field based methods. Remote sensing, using weather, and light independent SAR satellites has the potential of filling these data gaps, however, to date their use was limited by high acquisition costs, long repeat cycles, and small ground swath. Sentinel-1A (S1A), on the other hand, operational since October 2014 provides free-of-charge, 20 m spatial resolution, 250 km × 150 km ground swath images every 12 days. In this paper, we present for the first time, that it is possible to detect avalanche debris using S1A images. We successfully apply a change detection method that enhances avalanche debris zones, by comparing repeat pass images before and after the avalanche occurred. Due to the increase in backscatter from avalanche debris, manual detection is possible. With this first proof-of-concept, we show the detection of 489 avalanche debris zones in a S1A image from 6 January 2015, covering the counties Troms and parts of Nordland in Northern Norway. We validate our avalanche detection using very high resolution Radarsat-2 Ultrafine images, as well as extensive field reconnaissance. Our results give us confidence, that S1A detection of avalanches is a critical step towards operational use of SAR avalanche detection in avalanche forecasting.

  3. Alaskan wave and river hydrokinetic energy resource assessment, river energy converter testing and surface debris mitigation performance

    NASA Astrophysics Data System (ADS)

    Johnson, J.; Kasper, J.; Schmid, J.; Duvoy, P.; Ravens, T. M.; Hansen, N.; Montlaur, A.

    2014-12-01

    The Alaska Hydrokinetic Energy Research Center (AHERC) is conducting a wave energy assessment study at Yakutat, Alaska, and conducting ongoing river technology studies at the Tanana River Tests Site (TRTS) at Nenana, Alaska. In Aug. 2013 an acoustic Doppler current profiler (ADCP) was deployed in 40 m of water off Cannon Beach in Yakutat, AK as part of the Yakutat area wave energy resource assessment. Over the course of the 1.5 year deployment, the ADCP will record area wave and current data in order to verify the area wave energy resource. Preliminary data analysis shows a vigorous wave field with maximum wave heights up to 16 m in Nov. 2013. In addition to the in-situ directional wave data recorded by the ADCP, a SWAN wave climatology spanning the past 20 years is being developed along with a simulation of the wave field for the near shore (5 mdebris diversion platform (RDDP) at protecting a 5 kW New Energy hydrokinetic turbine from river debris flows and to determine the effect of RDDP generated river current turbulence on turbine efficiency. Previous tests have shown that the RDDP effectively sheds debris, however, large debris objects can cause RDDP rotation about its mooring point requiring that a stable attachment between the RDDP and protected floating structure be in place to ensure that debris is diverted away from the protected structure. Performance tests of an Oceana hydrokinetic power turbine will be conducted in late August or early September, 2014 at the TRTS in realistic Alaskan river conditions of current turbulence, high sediment flow and debris. Measurements of river sediment concentration, current velocity and river stage will be made, and current turbulence will be derived. CFD simulations of the RDDP interaction with the river flow will be completed to compare current velocity and turbulence results, depending on

  4. Debris - Onboard GT-10

    NASA Image and Video Library

    1966-07-18

    S66-46241 (18 July 1966) --- Debris on spacecraft window in picture taken from inside the Gemini-10 spacecraft. At this time Gemini-10 was docked with the Agena Target Docking Vehicle 5005. Taken with a modified 70mm Hasselblad camera, using Eastman Kodak, Ektachrome, MS (S.O. 217) color film. The Gemini-10 crew is astronaut John W. Young, command pilot, and Michael Collins, pilot. Photo credit: NASA

  5. Orbital debris issues

    NASA Astrophysics Data System (ADS)

    Kessler, D. J.

    Orbital debris issues fall into three major topics: Environment Definition, Spacecraft Hazard, and Space Object Management. The major issue under Environment Definition is defining the debris flux for sizes smaller (10 cm in diameter) than those tracked by the North American Aerospace Defense Command (NORAD). Sources for this size debris are fragmentation of larger objects, either by explosion or collision, and solid rocket motor products. Modeling of these sources can predict fluxes in low Earth orbit which are greater than the meteoroid environment. Techniques to measure the environment in the size interval between 1 mm and 10 cm are being developed, including the use of telescopes and radar both on the ground and in space. Some impact sensors designed to detect meteoroids may have detected solid rocket motor products. Once the environment is defined, it can be combined with hypervelocity impact data and damage criteria to evaluate the Spacecraft Hazard. Shielding may be required to obtain an acceptable damage level. Space Object Management includes techniques to control the environment and the desired policy to effectively minimize the hazard to spacecraft. One control technique - reducing the likelihood of future explosions in space - has already been implemented by NASA. The effectiveness of other techniques has yet to be evaluated.

  6. Simultaneous infrared and optical observations of the transiting debris cloud around WD 1145+017

    NASA Astrophysics Data System (ADS)

    Zhou, G.; Kedziora-Chudczer, L.; Bailey, J.; Marshall, J. P.; Bayliss, D. D. R.; Stockdale, C.; Nelson, P.; Tan, T. G.; Rodriguez, J. E.; Tinney, C. G.; Dragomir, D.; Colon, K.; Shporer, A.; Bento, J.; Sefako, R.; Horne, K.; Cochran, W.

    2016-12-01

    We present multiwavelength photometric monitoring of WD 1145+017, a white dwarf exhibiting periodic dimming events interpreted to be the transits of orbiting, disintegrating planetesimals. Our observations include the first set of near-infrared light curves for the object, obtained on multiple nights over the span of 1 month, and recorded multiple transit events with depths varying between ˜20 and 50 per cent. Simultaneous near-infrared and optical observations of the deepest and longest duration transit event were obtained on two epochs with the Anglo-Australian Telescope and three optical facilities, over the wavelength range of 0.5-1.2 μm. These observations revealed no measurable difference in transit depths for multiple photometric pass bands, allowing us to place a 2σ lower limit of 0.8 μm on the grain size in the putative transiting debris cloud. This conclusion is consistent with the spectral energy distribution of the system, which can be fit with an optically thin debris disc with minimum particle sizes of 10^{+5}_{-3} μm.

  7. Space Debris Modeling at NASA

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2001-01-01

    Since the Second European Conference on Space Debris in 1997, the Orbital Debris Program Office at the NASA Johnson Space Center has undertaken a major effort to update and improve the principal software tools employed to model the space debris environment and to evaluate mission risks. NASA's orbital debris engineering model, ORDEM, represents the current and near-term Earth orbital debris population from the largest spacecraft to the smallest debris in a manner which permits spacecraft engineers and experimenters to estimate the frequency and velocity with which a satellite may be struck by debris of different sizes. Using expanded databases and a new program design, ORDEM2000 provides a more accurate environment definition combined with a much broader array of output products in comparison with its predecessor, ORDEM96. Studies of the potential long-term space debris environment are now conducted with EVOLVE 4.0, which incorporates significant advances in debris characterization and breakup modeling. An adjunct to EVOLVE 4.0, GEO EVOLVE has been created to examine debris issues near the geosynchronous orbital regime. In support of NASA Safety Standard 1740.14, which establishes debris mitigation guidelines for all NASA space programs, a set of evaluation tools called the Debris Assessment Software (DAS) is specifically designed for program offices to determine whether they are in compliance with NASA debris mitigation guidelines. DAS 1.5 has recently been released with improved WINDOWS compatibility and graphics functions. DAS 2.0 will incorporate guideline changes in a forthcoming revision to NASA Safety Standard 1740.14. Whereas DAS contains a simplified model to calculate possible risks associated with satellite reentries, NASA's higher fidelity Object Reentry Survival Analysis Tool (ORSAT) has been upgraded to Version 5.0. With the growing awareness of the potential risks posed by uncontrolled satellite reentries to people and property on Earth, the

  8. January | 201span>6 | Ground Systems Development and Operations ...

    NASA Website

    August 201span>6; July 201span>6; June 201span>6; May 201span>6; April 201span>6; March 201span>6; February 201span>6; January 201span>6; December 2015; November 2015; October 2015; ...

  9. Origin of Subglacial Debris-bed Friction

    NASA Astrophysics Data System (ADS)

    Cohen, D. O.; Byers, J.; Iverson, N. R.

    2011-12-01

    Numerical models of glaciers sliding on hard beds assume that basal flow resistance is controlled entirely by viscous drag on bedrock bumps. However, observations and measurements indicate that basal ice can contain large concentrations of rock debris that exert significant frictional resistance: for example, locally high shear stress (˜500 kPa) was measured below 200 m of ice on a smooth rock tablet at the bed of Engabreen, Norway. This value of shear stress is an order of magnitude greater than estimated by leading theories. To better understand the origin of debris-bed friction, we built a new laboratory apparatus that recorded the contact force between a clast and a hard bed as a function of ice velocity toward the bed. An independent experiment with the same apparatus in which the clast is isolated from the bed was used to obtain the ice viscosity. After correcting for cavity formation and ice flow geometry, results indicate that the contact force between a clast and a hard bed is about twice the drag force on the same clast estimated using Stokes's law. This value is insufficient to explain the high debris-bed friction measured beneath Engabreen. An alternative explanation is that longitudinal ice extension caused by ice flowing over the rough topography near the smooth rock tablet increased the rate of ice convergence with the bed by a factor of 5. Our measurements confirm that debris-bed friction is controlled by contact forces caused by flow of ice towards the bed due to basal melting and longitudinal ice extension. This form of frictional drag has yet to be included in models of ice flow. Inclusion of debris-bed friction may prove important to properly estimating rates of basal sliding, energy dissipation and meltwater production at the bed, and, more importantly, to quantifying the stick-slip behavior of hard-bedded glaciers.

  10. External tank space debris considerations

    NASA Technical Reports Server (NTRS)

    Elfer, N.; Baillif, F.; Robinson, J.

    1992-01-01

    Orbital debris issues associated with maintaining a Space Shuttle External Tank (ET) on orbit are presented. The first issue is to ensure that the ET does not become a danger to other spacecraft by generating space debris, and the second is to protect the pressurized ET from penetration by space debris or meteoroids. Tests on shield designs for penetration resistance showed that when utilized with an adequate bumper, thermal protection system foam on the ET is effective in preventing penetration.

  11. DEBRIS FLOWS AND HYPERCONCENTRATED STREAMFLOWS.

    USGS Publications Warehouse

    Wieczorek, Gerald F.

    1986-01-01

    Examination of recent debris-flow and hyperconcentrated-streamflow events in the western United States reveals (1) the topographic, geologic, hydrologic, and vegetative conditions that affect initiation of debris flows and (2) the wide ranging climatic conditions that can trigger debris flows. Recognition of these physiographic and climatic conditions has aided development of preliminary methods for hazard evaluation. Recent developments in the application of electronic data gathering, transmitting, and processing systems shows potential for real-time hazard warning.

  12. Current Issues in Orbital Debris

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2011-01-01

    During the past two decades, great strides have been made in the international community regarding orbital debris mitigation. The majority of space-faring nations have reached a consensus on an initial set of orbital debris mitigation measures. Implementation of and compliance with the IADC and UN space debris mitigation guidelines should remain a high priority. Improvements of the IADC and UN space debris mitigation guidelines should continue as technical consensus permits. The remediation of the near-Earth space environment will require a significant and long-term undertaking.

  13. Depositional processes in large-scale debris-flow experiments

    USGS Publications Warehouse

    Major, J.J.

    1997-01-01

    This study examines the depositional process and characteristics of deposits of large-scale experimental debris flows (to 15 m3) composed of mixtures of gravel (to 32 mm), sand, and mud. The experiments were performed using a 95-m-long, 2-m-wide debris-flow flume that slopes 31??. Following release, experimental debris flows invariably developed numerous shallow (???10 cm deep) surges. Sediment transported by surges accumulated abruptly on a 3?? runout slope at the mouth of the flume. Deposits developed in a complex manner through a combination of shoving forward and shouldering aside previously deposited debris and through progressive vertical accretion. Progressive accretion by the experimental flows is contrary to commonly assumed en masse sedimentation by debris flows. Despite progressive sediment emplacement, deposits were composed of unstratified accumulations of generally unsorted debris; hence massively textured, poorly sorted debris-flow deposits are not emplaced uniquely en masse. The depositional process was recorded mainly by deposit morphology and surface texture and was not faithfully registered by interior sedimentary texture; homogeneous internal textures could be misinterpreted as the result of en masse emplacement by a single surge. Deposition of sediment by similar, yet separate, debris flows produced a homogenous, massively textured composite deposit having little stratigraphic distinction. Similar deposit characteristics and textures are observed in natural debris-flow deposits. Experimental production of massively textured deposits by progressive sediment accretion limits interpretations that can be drawn from deposit characteristics and casts doubt on methods of estimating flow properties from deposit thickness or from relations between particle size and bed thickness.

  14. Removal of orbital debris

    NASA Technical Reports Server (NTRS)

    Petro, Andrew J.; Talent, David L.

    1989-01-01

    The several methods presently identified for the reduction of orbital debris populations are broadly classifiable as either preventive or remedial, and fall within distinctive operational regimes. For all particles, (1) in the 250-2000-km altitude band, intelligent sweepers may be used; (2) for large objects, in the 80-250-km altitude band, orbital decay renders removal impractical; (3) for the 250-750-km altitude band, deorbit devices should be used; (4) for 750-2500-km altitude, OMV rendezvous for propulsive deorbit package attachment is foreseeable; and beyond 2500 km, (5) propulsive escape from earth orbit is required.

  15. Space Debris Hazard Evaluation

    NASA Technical Reports Server (NTRS)

    Davison, Elmer H.; Winslow, Paul C., Jr.

    1961-01-01

    The hazard to space vehicles from natural space debris has been explored. A survey of the available information pertinent to this problem is presented. The hope is that this presentation gives a coherent picture of the knowledge to date in terms of the topic covered. The conclusion reached is that a definite hazard exists but that it can only be poorly assessed on the basis of present information. The need for direct measurement of this hazard is obvious, and some of the problems involved in making these direct measurements have been explored.

  16. Removal of orbital debris

    NASA Astrophysics Data System (ADS)

    Petro, Andrew J.; Talent, David L.

    The several methods presently identified for the reduction of orbital debris populations are broadly classifiable as either preventive or remedial, and fall within distinctive operational regimes. For all particles, (1) in the 250-2000-km altitude band, intelligent sweepers may be used; (2) for large objects, in the 80-250-km altitude band, orbital decay renders removal impractical; (3) for the 250-750-km altitude band, deorbit devices should be used; (4) for 750-2500-km altitude, OMV rendezvous for propulsive deorbit package attachment is foreseeable; and beyond 2500 km, (5) propulsive escape from earth orbit is required.

  17. Removal of orbital debris

    NASA Technical Reports Server (NTRS)

    Petro, Andrew J.; Talent, David L.

    1989-01-01

    The several methods presently identified for the reduction of orbital debris populations are broadly classifiable as either preventive or remedial, and fall within distinctive operational regimes. For all particles, (1) in the 250-2000-km altitude band, intelligent sweepers may be used; (2) for large objects, in the 80-250-km altitude band, orbital decay renders removal impractical; (3) for the 250-750-km altitude band, deorbit devices should be used; (4) for 750-2500-km altitude, OMV rendezvous for propulsive deorbit package attachment is foreseeable; and beyond 2500 km, (5) propulsive escape from earth orbit is required.

  18. An efficient algorithm for orbital evolution of space debris

    NASA Astrophysics Data System (ADS)

    Abdel-Aziz, Y.; Abd El-Salam, F.

    satellites and space debris. The present paper developes a second order theory of perturbations (in the sense of the Hori-Lie perturbation method), that include the geopotential effect, luni-solar perturbations, solar radiation pressure and atmospheric drag. Resonance and very long period perturbations are modeled with the use of semi-secular terms for a short time span predictions. We present a comparision of our analytical solution with numerical integration of motion for chosen artificial satellites at (Low, MEO, GEO), also for different spase debris objets with different are-to-mass ratios showing good accuracy of the theory.

  19. A debris avalanche at Forest Falls, San Bernardino County, California, July 11, 1999

    USGS Publications Warehouse

    Morton, Douglas M.; Hauser, Rachel M.

    2001-01-01

    This publication consists of the online version of a CD-ROM publication, U.S. Geological Survey Open-File Report 01-146. The data for this publication total 557 MB on the CD-ROM. For speed of transfer, the main PDF document has been compressed (with a subsequent loss of image quality) from 145 to 18.1 MB. The community of Forest Falls, California, is frequently subject to relatively slow moving debris flows. Some 11 debris flow events that were destructive to property have been recorded between 1955 and 1998. On July 11 and 13, 1999, debris flows again occurred, produced by high-intensity, short-duration monsoon rains. Unlike previous debris flow events, the July 11 rainfall generated a high-velocity debris avalanche in Snow Creek, one of the several creeks crossing the composite, debris flow dominated, alluvial fan on which Forest Falls is located. This debris avalanche overshot the bank of the active debris flow channel of Snow Creek, destroying property in the near vicinity and taking a life. The minimum velocity of this avalanche is calculated to have been in the range of 40 to 55 miles per hour. Impact from high-velocity boulders removed trees where the avalanche overshot the channel bank. Further down the fan, the rapidly moving debris fragmented the outer parts of the upslope side of large pine trees and embedded rock fragments into the tree trunks. Unlike the characteristic deposits formed by debris flows, the avalanche spread out down-slope and left no deposit suggestive of a debris avalanche. This summer monsoon-generated debris avalanche is apparently the first recorded for Forest Falls. The best indications of past debris avalanches may be the degree of permanent scars produced by extensive abrasion and splintering of the outer parts of pine trees that were in the path of an avalanche.

  20. Space debris executive summary

    SciTech Connect

    Canavan, G.H.; Judd, O.; Naka, R.F.

    1996-09-01

    Spacecraft, boosters, and fragments are potential hazards to space vehicles, and it is argued that collisions between them could produce a cascade that could preclude activity in LEO in 25 to 50 years. That has generated pressure for constraints on military space operations, so the AF SAB performed a study of technical aspects of the debris problem. The Study was independent of the efforts of the Air Force Space Command (AFSPC) as well as those of and NASA Johnson Space Center (JSC), which is the principal advocate for cascades and constraints. Most work on space debris has been performed by AFSPC and JSC, so the Study was in part an assessment of their efforts, in which both have been cooperative. The Study identified the main disagreements and quantified their impacts. It resolved some issues and provided bounds for the rest. It treated radar and optical observations; launch, explosion, and decay rates; and the number and distribution of fragments from explosions and collisions. That made it possible to address hazard to manned spacecraft at low altitudes and the possibility of cascading at higher altitudes, both of which now appear less likely.

  1. Debris-carrying camouflage among diverse lineages of Cretaceous insects.

    PubMed

    Wang, Bo; Xia, Fangyuan; Engel, Michael S; Perrichot, Vincent; Shi, Gongle; Zhang, Haichun; Chen, Jun; Jarzembowski, Edmund A; Wappler, Torsten; Rust, Jes

    2016-06-01

    Insects have evolved diverse methods of camouflage that have played an important role in their evolutionary success. Debris-carrying, a behavior of actively harvesting and carrying exogenous materials, is among the most fascinating and complex behaviors because it requires not only an ability to recognize, collect, and carry materials but also evolutionary adaptations in related morphological characteristics. However, the fossil record of such behavior is extremely scarce, and only a single Mesozoic example from Spanish amber has been recorded; therefore, little is known about the early evolution of this complicated behavior and its underlying anatomy. We report a diverse insect assemblage of exceptionally preserved debris carriers from Cretaceous Burmese, French, and Lebanese ambers, including the earliest known chrysopoid larvae (green lacewings), myrmeleontoid larvae (split-footed lacewings and owlflies), and reduviids (assassin bugs). These ancient insects used a variety of debris material, including insect exoskeletons, sand grains, soil dust, leaf trichomes of gleicheniacean ferns, wood fibers, and other vegetal debris. They convergently evolved their debris-carrying behavior through multiple pathways, which expressed a high degree of evolutionary plasticity. We demonstrate that the behavioral repertoire, which is associated with considerable morphological adaptations, was already widespread among insects by at least the Mid-Cretaceous. Together with the previously known Spanish specimen, these fossils are the oldest direct evidence of camouflaging behavior in the fossil record. Our findings provide a novel insight into early evolution of camouflage in insects and ancient ecological associations among plants and insects.

  2. Debris-carrying camouflage among diverse lineages of Cretaceous insects

    PubMed Central

    Wang, Bo; Xia, Fangyuan; Engel, Michael S.; Perrichot, Vincent; Shi, Gongle; Zhang, Haichun; Chen, Jun; Jarzembowski, Edmund A.; Wappler, Torsten; Rust, Jes

    2016-01-01

    Insects have evolved diverse methods of camouflage that have played an important role in their evolutionary success. Debris-carrying, a behavior of actively harvesting and carrying exogenous materials, is among the most fascinating and complex behaviors because it requires not only an ability to recognize, collect, and carry materials but also evolutionary adaptations in related morphological characteristics. However, the fossil record of such behavior is extremely scarce, and only a single Mesozoic example from Spanish amber has been recorded; therefore, little is known about the early evolution of this complicated behavior and its underlying anatomy. We report a diverse insect assemblage of exceptionally preserved debris carriers from Cretaceous Burmese, French, and Lebanese ambers, including the earliest known chrysopoid larvae (green lacewings), myrmeleontoid larvae (split-footed lacewings and owlflies), and reduviids (assassin bugs). These ancient insects used a variety of debris material, including insect exoskeletons, sand grains, soil dust, leaf trichomes of gleicheniacean ferns, wood fibers, and other vegetal debris. They convergently evolved their debris-carrying behavior through multiple pathways, which expressed a high degree of evolutionary plasticity. We demonstrate that the behavioral repertoire, which is associated with considerable morphological adaptations, was already widespread among insects by at least the Mid-Cretaceous. Together with the previously known Spanish specimen, these fossils are the oldest direct evidence of camouflaging behavior in the fossil record. Our findings provide a novel insight into early evolution of camouflage in insects and ancient ecological associations among plants and insects. PMID:27386568

  3. A quantification of the standing stock of macro-debris in Majuro lagoon and its effect on hard coral communities.

    PubMed

    Richards, Zoe T; Beger, Maria

    2011-08-01

    The accumulation of debris is an insidious problem throughout the world's oceans. Here we document 234.24 items of macro-debris/km2 in the shallow populated parts of Majuro lagoon (Republic of the Marshall Islands) which is the second highest standing stock of macro-debris recorded to date in any benthic marine habitat in the world. The majority of macro-debris was from household sources (78.7%) with the peak abundance recorded in areas of medium affluence. Marine debris causes suffocation, shading, tissue abrasion and mortality of corals and we show a significant negative correlation exists between the level of hard coral cover and coverage of marine debris. Given long decomposition times, even if the input of rubbish to Majuro lagoon is stopped immediately, the standing stock of debris will persist for centuries. Multiple new initiatives are needed to curtail the direct and indirect dumping of waste in Majuro lagoon.

  4. Space debris modeling at NASA

    NASA Astrophysics Data System (ADS)

    Johnson, Nicholas L.

    2001-10-01

    Since the Second European Conference on Space Debris in 1997, the Orbital Debris Program Office at the NASA Johnson Space Center has undertaken a major effort to update and improve the principal software tools employed to model the space debris environment and to evaluate mission risks. NASA's orbital debris engineering model, ORDEM, represents the current and near-term Earth orbital debris population from the largest spacecraft to the smallest debris in a manner which permits spacecraft engineers and experimenters to estimate the frequency and velocity with which a satellite may be struck by debris of different sizes. Using expanded databases and a new program design, ORDEM2000 provides a more accurate environment definition combined with a much broader array of output products in comparison with its predecessor, ORDEM96. Studies of the potential long-term space debris environment are now conducted with EVOVLE 4.0, which incorporates significant advances in debris characterization and breakup modeling. An adjunct to EVOLVE 4.0, GEO EVOLVE has been created to examine debris issues near the geosynchronous orbital regime. In support of NASA Safety Standard (NSS) 1740.14, which establishes debris mitigation guidelines for all NASA space programs, a set of evaluation tools called the Debris Assessment Software (DAS) is specifically designed for program offices to determine whether they are in compliance with NASA debris mitigation guidelines. DAS 1.5 has recently been completed with improved WINDOWS compatibility and graphics functions. DAS 2.0 will incorporate guideline changes in a forthcoming revision to NSS 1740.14. Whereas DAS contains a simplified model to calculate possible risks associated with satellite reentries, NASA's higher fidelity Object Reentry Survival Analysis Tool (ORSAT) has been upgraded to Version 5.0. With the growing awareness of the potential risks posed by uncontrolled satellite reentries to people and property on Earth, the application of

  5. Remote Sensing of Plastic Debris

    NASA Astrophysics Data System (ADS)

    Garaba, S. P.; Dierssen, H. M.

    2016-02-01

    Plastic debris is becoming a nuisance in the environment and as a result there has been a dire need to synoptically detect and quantify them in the ocean and on land. We investigate the possible utility of spectral information determined from hand held, airborne and satellite remote sensing tools in the detection and identification polymer source of plastic debris. Sampled debris will be compared to our derived spectral library of typical raw polymer sources found at sea and in household waste. Additional work will be to determine ways to estimate the abundance of plastic debris in target areas. Implications of successful remote detection, tracking and quantification of plastic debris will be towards validating field observations over large areas and at repeated time intervals both on land and at sea.

  6. The Challenge of Orbital Debris

    NASA Technical Reports Server (NTRS)

    Matney, Mark

    2012-01-01

    Since the dawn of the Space Age more than 50 years ago, humans have been launching objects into the space environment faster than they have been removed by active means or natural decay. This has led to a proliferation of debris -- derelict satellites, discarded rocket upper stages, and pieces from satellite breakups -- in Earth orbit, especially in well-used orbital regimes. This talk will summarize the current knowledge of the debris environment and describe plans to address the challenges orbital debris raises for the future usability of near-Earth space. The talk will be structured around 4 categories: Measurements, Modeling, Shielding, and Mitigation. This will include discussions of the long-term prognosis of debris growth (i.e., the "Kessler Syndrome") as well as plans for active debris removal.

  7. July | 201span>6 | ISS On-Orbit Status Report

    NASA Website

    Monday, 08/01: Airway Monitoring Airlock ops, SPHERES, ... August 201span>6; July 201span>6; June 201span>6; May 201span>6; April 201span>6; March 201span>6; February 201span>6; January ...

  8. Space debris: modeling and detectability

    NASA Astrophysics Data System (ADS)

    Wiedemann, C.; Lorenz, J.; Radtke, J.; Kebschull, C.; Horstmann, A.; Stoll, E.

    2017-01-01

    High precision orbit determination is required for the detection and removal of space debris. Knowledge of the distribution of debris objects in orbit is necessary for orbit determination by active or passive sensors. The results can be used to investigate the orbits on which objects of a certain size at a certain frequency can be found. The knowledge of the orbital distribution of the objects as well as their properties in accordance with sensor performance models provide the basis for estimating the expected detection rates. Comprehensive modeling of the space debris environment is required for this. This paper provides an overview of the current state of knowledge about the space debris environment. In particular non-cataloged small objects are evaluated. Furthermore, improvements concerning the update of the current space debris model are addressed. The model of the space debris environment is based on the simulation of historical events, such as fragmentations due to explosions and collisions that actually occurred in Earth orbits. The orbital distribution of debris is simulated by propagating the orbits considering all perturbing forces up to a reference epoch. The modeled object population is compared with measured data and validated. The model provides a statistical distribution of space objects, according to their size and number. This distribution is based on the correct consideration of orbital mechanics. This allows for a realistic description of the space debris environment. Subsequently, a realistic prediction can be provided concerning the question, how many pieces of debris can be expected on certain orbits. To validate the model, a software tool has been developed which allows the simulation of the observation behavior of ground-based or space-based sensors. Thus, it is possible to compare the results of published measurement data with simulated detections. This tool can also be used for the simulation of sensor measurement campaigns. It is

  9. Orbital Debris Research at NASA

    NASA Technical Reports Server (NTRS)

    Stansbery, Eugene G.

    2009-01-01

    The United States has one of the most active programs of research of the orbital debris environment in the world. Much of the research is conducted by NASA s Orbital Debris Program Office at the Johnson Space Center. Past work by NASA has led to the development of national space policy which seeks to limit the growth of the debris population and limit the risk to spacecraft and humans in space and on the Earth from debris. NASA has also been instrumental in developing consistent international policies and standards. Much of NASA's efforts have been to measure and characterize the orbital debris population. The U.S. Department of Defense tracks and catalogs spacecraft and large debris with it's Space Surveillance Network while NASA concentrates on research on smaller debris. In low Earth orbit, NASA has utilized short wavelength radars such as Haystack, HAX, and Goldstone to statistically characterize the population in number, size, altitude, and inclination. For higher orbits, optical telescopes have been used. Much effort has gone into the understanding and removal of observational biases from both types of measurements. NASA is also striving to understand the material composition and shape characteristics of debris to assess these effects on the risk to operational spacecraft. All of these measurements along with data from ground tests provide the basis for near- and long-term modeling of the environment. NASA also develops tools used by spacecraft builders and operators to evaluate spacecraft and mission designs to assess compliance with debris standards and policies which limit the growth of the debris environment.

  10. An Introduction to Space Debris

    NASA Astrophysics Data System (ADS)

    Wright, David

    2008-04-01

    Space debris is any human-made object in orbit that no longer serves a useful purpose, including defunct satellites, discarded equipment and rocket stages, and fragments from the breakup of satellites and rocket stages. It is a concern because--due to its very high speed in orbit--even relatively small pieces can damage or destroy satellites in a collision. Since debris at high altitudes can stay in orbit for decades or longer, it accumulates as more is produced and the risk of collisions with satellites grows. Since there is currently no effective way to remove large amounts of debris from orbit, controlling the production of debris is essential for preserving the long-term use of space. Today there are 860 active satellites in orbit, supporting a wide range of civil and military uses. The 50 years of space activity since the launch of Sputnik 1 has also resulted in well over half a million pieces of orbiting debris larger than 1 cm in size. There are two main sources of space debris: (1) routine space activity and the accidental breakup of satellites and stages placed in orbit by such activity, and (2) the testing or use of destructive anti-satellite (ASAT) weapons that physically collide with satellites at high speed. The international community is attempting to reduce the first category by developing strict guidelines to limit the debris created as a result of routine space activities. However, the destruction of a single large spy satellite by an ASAT weapon could double the total amount of large debris in low earth orbit, and there are currently no international restrictions on these systems. This talk will give an introduction to what's in space, the origins of space debris, efforts to stem its growth, the threat it poses to satellites in orbit, and the long-term evolution of the debris population.

  11. Contrasting rainfall generated debris flows from adjacent watersheds at Forest Falls, southern California, USA

    USGS Publications Warehouse

    Morton, D.M.; Alvarez, R.M.; Ruppert, K.R.; Goforth, B.

    2008-01-01

    channel. After the channel is blocked, subsequent debris flows cut a new channel upstream from the blockage that results in the deposition of new debris-flow deposits on the lower part of the fan. Shifting the location of debris flows on the Rattlesnake Creek fan tends to prevent trees from becoming mature. Dense growths of conifer seedlings sprout in the spring on the late summer debris flow deposits. This repeated process results in stands of even-aged trees whose age records the age of the debris flows. ?? 2007.

  12. Influence of hydrometeorological controls on debris flows near Chilliwack, British Columbia

    NASA Astrophysics Data System (ADS)

    Sutton, L.; Kohfeld, K. E.; Cooper, A. B.

    2011-12-01

    The combination of mountainous terrain, coastal weather systems, and orographic precipitation leaves communities in southwestern British Columbia susceptible to human and economic losses caused by precipitation driven debris flows. Between 1980 and 2007 the region around Chilliwack, BC was struck by 30 reported debris flows which closed highways, stopped rail service, and caused many residents to evacuate their homes. All of these debris flow occurred during storms with greater than 50 mm of rain. Understanding which hydrometeorological conditions are associated with debris flow occurrence in the past may provide information for planners responsible for decision making in the face of climate change. Throughout the next century, climate change is expected to influence precipitation patterns, including frequency and intensity, which in turn may affect the occurrence of future debris flows. This study aims to identify hydrometeorological variables which have initiated past debris flows in order to gain insight about conditions that could inform emergency planning. A database of 185 storms from 1980 to 2007 and their hydrometeorological characteristics, including storm total rainfall and duration, intense rainfall total and duration, and 1 to 4 week cumulative antecedent rainfall were compiled. Storms were classified as debris flow initiating or non-debris flow initiating based on a historical record of reported debris flows. Logistic regression was used to determine the probability of a storm's classification as debris flow or non-debris flow initiating based on significant hydrometeorological variables. The outcome of this statistical analysis revealed three main findings. First, the analysis suggests that the total amount of consecutive days of intense rainfall above 25 mm/24 hours is the most significant hydrometeorological variable contributing to debris flows near Chilliwack. Second, although intense rainfall total was significant, it does not fully differentiate

  13. Contrasting rainfall generated debris flows from adjacent watersheds at Forest Falls, southern California, USA

    NASA Astrophysics Data System (ADS)

    Morton, Douglas M.; Alvarez, Rachel M.; Ruppert, Kelly R.; Goforth, Brett

    2008-04-01

    . After the channel is blocked, subsequent debris flows cut a new channel upstream from the blockage that results in the deposition of new debris-flow deposits on the lower part of the fan. Shifting the location of debris flows on the Rattlesnake Creek fan tends to prevent trees from becoming mature. Dense growths of conifer seedlings sprout in the spring on the late summer debris flow deposits. This repeated process results in stands of even-aged trees whose age records the age of the debris flows.

  14. Spatial patterns of plastic debris along Estuarine shorelines.

    PubMed

    Browne, Mark A; Galloway, Tamara S; Thompson, Richard C

    2010-05-01

    The human population generates vast quantities of waste material. Macro (>1 mm) and microscopic (<1 mm) fragments of plastic debris represent a substantial contamination problem. Here, we test hypotheses about the influence of wind and depositional regime on spatial patterns of micro- and macro-plastic debris within the Tamar Estuary, UK. Debris was identified to the type of polymer using Fourier-transform infrared spectroscopy (FT-IR) and categorized according to density. In terms of abundance, microplastic accounted for 65% of debris recorded and mainly comprised polyvinylchloride, polyester, and polyamide. Generally, there were greater quantities of plastic at downwind sites. For macroplastic, there were clear patterns of distribution for less dense items, while for microplastic debris, clear patterns were for denser material. Small particles of sediment and plastic are both likely to settle slowly from the water-column and are likely to be transported by the flow of water and be deposited in areas where the movements of water are slower. There was, however, no relationship between the abundance of microplastic and the proportion of clay in sediments from the strandline. These results illustrate how FT-IR spectroscopy can be used to identify the different types of plastic and in this case was used to indicate spatial patterns, demonstrating habitats that are downwind acting as potential sinks for the accumulation of debris.

  15. Assessment of marine debris on the Belgian Continental Shelf.

    PubMed

    Van Cauwenberghe, Lisbeth; Claessens, Michiel; Vandegehuchte, Michiel B; Mees, Jan; Janssen, Colin R

    2013-08-15

    A comprehensive assessment of marine litter in three environmental compartments of Belgian coastal waters was performed. Abundance, weight and composition of marine debris, including microplastics, was assessed by performing beach, sea surface and seafloor monitoring campaigns during two consecutive years. Plastic items were the dominant type of macrodebris recorded: over 95% of debris present in the three sampled marine compartments were plastic. In general, concentrations of macrodebris were quite high. Especially the number of beached debris reached very high levels: on average 6429±6767 items per 100 m were recorded. Microplastic concentrations were determined to assess overall abundance in the different marine compartments of the Belgian Continental Shelf. In terms of weight, macrodebris still dominates the pollution of beaches, but in the water column and in the seafloor microplastics appear to be of higher importance: here, microplastic weight is approximately 100 times and 400 times higher, respectively, than macrodebris weight.

  16. Implementation of the hazardous debris rule

    SciTech Connect

    Sailer, J.E.

    1993-01-05

    Hazardous debris includes objects contaminated with hazardous waste. Examples of debris include tree stumps, timbers, boulders, tanks, piping, crushed drums, personal protective clothing, etc. Most of the hazardous debris encountered comes from Superfund sites and other facility remediation, although generators and treaters of hazardous waste also generate hazardous debris. Major problems associated with disposal of debris includes: Inappropriateness of many waste treatments to debris; Difficulties in obtaining representative samples; Costs associated with applying waste specific treatments to debris; Subtitle C landfill space was being used for many low hazard debris types. These factors brought about the need for debris treatment technologies and regulations that addressed these issues. The goal of such regulation was to provide treatment to destroy or remove the contamination if possible and, if this is achieved, to dispose of the cleaned debris as a nonhazardous waste. EPA has accomplished this goal through promulgation of the Hazardous Debris Rule, August 18, 1992.

  17. Temporal variability of marine debris deposition at Tern Island in the Northwestern Hawaiian Islands.

    PubMed

    Agustin, Alyssa E; Merrifield, Mark A; Potemra, James T; Morishige, Carey

    2015-12-15

    A twenty-two year record of marine debris collected on Tern Island is used to characterize the temporal variability of debris deposition at a coral atoll in the Northwestern Hawaiian Islands. Debris deposition tends to be episodic, without a significant relationship to local forcing processes associated with winds, sea level, waves, and proximity to the Subtropical Convergence Zone. The General NOAA Operational Modeling Environment is used to estimate likely debris pathways for Tern Island. The majority of modeled arrivals come from the northeast following prevailing trade winds and surface currents, with trajectories indicating the importance of the convergence zone, or garbage patch, in the North Pacific High region. Although debris deposition does not generally exhibit a significant seasonal cycle, some debris types contain considerable 3 cycle/yr variability that is coherent with wind and surface pressure over a broad region north of Tern.

  18. The SPAN cookbook: A practical guide to accessing SPAN

    NASA Technical Reports Server (NTRS)

    Mason, Stephanie; Tencati, Ronald D.; Stern, David M.; Capps, Kimberly D.; Dorman, Gary; Peters, David J.

    1990-01-01

    This is a manual for remote users who wish to send electronic mail messages from the Space Physics Analysis Network (SPAN) to scientific colleagues on other computer networks and vice versa. In several instances more than one gateway has been included for the same network. Users are provided with an introduction to each network listed with helpful details about accessing the system and mail syntax examples. Also included is information on file transfers, remote logins, and help telephone numbers.

  19. JSC Orbital Debris Website Description

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2006-01-01

    Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as

  20. JSC Orbital Debris Website Description

    NASA Astrophysics Data System (ADS)

    Johnson, Nicholas L.

    2006-01-01

    Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as

  1. Debris flow hazards and risks on Cheekye Fan, British Columbia

    NASA Astrophysics Data System (ADS)

    Jakob, M.

    2009-04-01

    Natural hazard and risk assessments hinge fundamentally on a detailed understanding of the relationship between frequency and magnitude of the hazardous process under investigation. When information is sought from the deep past (i.e. several thousand years), continuous event records do not exist and the researcher has to rely on proxy data to develop the F-M model. Such work is often prohibitively expensive and few well researched examples for mass movement are available worldwide. Cheekye fan is a desirable location for land development and has a depth and breadth of previous research unprecedented on any debris flow fan in Canada. We pursued two principal strains of research to formulate a reliable frequency-magnitude relationship. The first focuses on stratigraphic analyses combined with radiometric dating and dendrochronology to reconstruct a comprehensive picture of Holocene debris flow activity. The second approach examines hydrological limitations of rock avalanche evolution into debris flows through either entrainment of saturated sediments or by failure of a landslide-generated dam and upstream impoundment. We thus hypothesize that debris flows from Cheekye River can be separated into two quasi homogenous populations: those that are typically triggered by relatively small debris avalanches, slumps or rock falls or simply by progressive bulking of in-stream erodible sediments; and those that are thought to result from transformation of rock avalanches. Our work suggests that debris flows exceeding some 3 million cubic metres in volume are unlikely to reach Cheekye fan due to limited water available to fully fluidize a rock avalanche. This analysis has also demonstrated that in order to arrive at reasonable estimates for the frequency and magnitude of debris flows on a complex alluvial fan, significant multidisciplinary efforts are required. As a second step in the analysis, we model the design debris flow using a two-dimensional debris flow runout model

  2. Debris disks: a theorist's view

    NASA Astrophysics Data System (ADS)

    Krivov, A. V.

    2007-08-01

    Debris disks are roughly solar system-sized, optically thin, gas-poor dust disks that encircle a notable fraction of main-sequence stars at ages ranging from about 10 Myr to several Gyr. They are thought to be continuously replenished by collisions between "exoasteroids" and activity of "exocomets", small bodies left over from the planet formation process. I will first outline main physical mechanisms operating in debris disks and compare them with other dusty systems: protoplanetary disks, dusty planetary rings, and classical Saturn's rings. I will then review basic methods and essential results of debris disks modeling, covering both steady-state and stochastic models of axisymmetric and structured disks.

  3. Herschel DEBRIS survey of debris discs around A stars

    NASA Astrophysics Data System (ADS)

    Thureau, N.

    2014-11-01

    The Herschel DEBRIS survey (Disc Emission via a Bias-free Reconnaissance in the Infrared/Submillimetre) brings a unique perspective to the study of debris discs around main-sequence A-type stars. We have observed a sample of 89 A-stars with the Photodetector Array Camera and Spectrometer (PACS) on the Herschel space telescope at 100 and 160 μm. A statistical analysis of the data shows a lower debris disc rate than has previously been found. The drop is due in part to the fact that some excess sources were resolved as background objects by the superior angular resolution (a factor of 2.5) of PACS-100 relative to that of Spitzer (MIPS-70). We found a 3-σ detection rate of 23 myblue which is similar to the the detection rate around main-sequence F, G and K stars. Most of the debris discs were detected around the youngest and hottest stars in our sample. The incidence of discs in single and multiple systems was similar. The debris discs in multiple systems ware found either in tight binary systems (<1 AU) or wide ones (>100 AU). Debris discs in both tight and wide binary systems have physical properties that are statistically similar to those of discs around single stars. We did not detect any debris discs in binary systems with intermediate separation, in which the orbit and the debris disc would be on the same scale. One possible explanation is that discs in intermediate systems have evolved much faster owing to the disc-companion interactions and they are now undetectable.

  4. Field observations of particle impacts by debris flows and debris floods on instrumented rock samples

    NASA Astrophysics Data System (ADS)

    McArdell, B. W.; Hsu, L.; Fritschi, B.; Dietrich, W. E.

    2011-12-01

    Bedrock incision and sediment entrainment by debris flows are important processes in torrent channels. As part of our effort to gain a better understanding of these processes, we installed instrumented rock samples in the bed of the Illgraben channel. Three rock samples, 0.4 m long (in the flow direction), 0.3 m wide, and 0.2 m thick, were installed in steel frames which were mounted on the upslope side of a concrete check dam, with the surface of the stones flush with the channel bed. Accelerometer sensors were installed on the bottom of one rock sample, with a range of up to 500 g (vertical) and 200 g (horizontal, parallel to the channel axis), where g is the acceleration due to gravity. Elastomer elements, typically used in the field as overload protection for load sensors, were placed between the rock samples and the steel frames. Data were sampled at 2 kHz and stored on a computer outside of the channel. The sensors provided data for 4 debris floods and part of one debris flow. For all of the events, the vertical acceleration data indicate a large background noise in the range of ±10 g, punctuated by very short duration impulses of up to several hundred g. The large accelerations are interpreted to represent hard impacts of cobbles or boulders in the flow with the rock tablet. Using a value of >20 g to define the occurrence of a large particle impact, it is possible to differentiate between debris floods (which have on the order of 0.1 impact per second) and the debris flow (on the order of 1 impact per second). The frequency of the sampling is too small to resolve details about the impacts, so it is not possible to precisely determine the maximum accelerations. However the peak recorded values are larger for debris flows, with values up to the measurement limit of the sensors, whereas for floods the maximum accelerations are typically less than 100 g. The results for the accelerometer which measures accelerations in the downstream direction generally mirror

  5. DEBRIS: a computer program for analyzing channel cross sections

    Treesearch

    Patrick Deenihan; Thomas E. Lisle

    1988-01-01

    DEBRIS is a menu-driven, interactive computer program written in FORTRAN 77 for recording and plotting survey data and for computing hydraulic variables and depths of scour and fill. It was developed for use with the USDA Forest Service's Data General computer system, with the AOS/VS operation system. By using menus, the operator does not need to know any...

  6. DEBRIS: A computer program for analyzing channel cross sections

    Treesearch

    Patrick Deenihan; Thomas E. Lisle

    1988-01-01

    DEBRIS is a menu-driven, interactive computer program written in FORTRAN 77 for recording and platting survey data and for computing hydraulic variables and depths of scour and fill. It was developed for use with the USDA Forest Service's Data General computer system, with the AOS/VS operating system. By using menus, the operator does not need to know any...

  7. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  8. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  9. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 44 Emergency Management and Assistance 1 2013-10-01 2013-10-01 false Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  10. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 44 Emergency Management and Assistance 1 2014-10-01 2014-10-01 false Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  11. Exploring the Dimensionality of Digit Span

    ERIC Educational Resources Information Center

    Bowden, Stephen C.; Petrauskas, Vilija M.; Bardenhagen, Fiona J.; Meade, Catherine E.; Simpson, Leonie C.

    2013-01-01

    The Digit Span subtest from the Wechsler Scales is used to measure Freedom from Distractibility or Working Memory. Some published research suggests that Digit Span forward should be interpreted differently from Digit Span backward. The present study explored the dimensionality of the Wechsler Memory Scale-III Digit Span (forward and backward)…

  12. Effects of basal debris on glacier flow.

    PubMed

    Iverson, Neal R; Cohen, Denis; Hooyer, Thomas S; Fischer, Urs H; Jackson, Miriam; Moore, Peter L; Lappegard, Gaute; Kohler, Jack

    2003-07-04

    Glacier movement is resisted partially by debris, either within glaciers or under glaciers in water-saturated layers. In experiments beneath a thick, sliding glacier, ice containing 2 to 11% debris exerted shear traction of 60 to 200 kilopascals on a smooth rock bed, comparable to the total shear traction beneath glaciers and contrary to the usual assumption that debris-bed friction is negligible. Imposed pore-water pressure that was 60 to 100% of the normal stress in a subglacial debris layer reduced shear traction on the debris sufficiently to halt its deformation and cause slip of ice over the debris. Slip resistance was thus less than debris shearing resistance.

  13. DIAGNOSING CIRCUMSTELLAR DEBRIS DISKS

    SciTech Connect

    Hahn, Joseph M.

    2010-08-20

    A numerical model of a circumstellar debris disk is developed and applied to observations of the circumstellar dust orbiting {beta} Pictoris. The model accounts for the rates at which dust is produced by collisions among unseen planetesimals, and the rate at which dust grains are destroyed due to collisions. The model also accounts for the effects of radiation pressure, which is the dominant perturbation on the disk's smaller but abundant dust grains. Solving the resulting system of rate equations then provides the dust abundances versus grain size and dust abundances over time. Those solutions also provide the dust grains' collisional lifetime versus grain size, and the debris disk's optical depth and surface brightness versus distance from the star. Comparison to observations then yields estimates of the unseen planetesimal disk's radius, and the rate at which the disk sheds mass due to planetesimal grinding. The model can also be used to measure or else constrain the dust grain's physical and optical properties, such as the dust grains' strength, their light-scattering asymmetry parameter, and the grains' efficiency of light scattering Q{sub s}. The model is then applied to optical observations of the edge-on dust disk orbiting {beta} Pictoris, and good agreement is achieved when the unseen planetesimal disk is broad, with 75 {approx}< r {approx}< 150 AU. If it is assumed that the dust grains are bright like Saturn's icy rings (Q{sub s} = 0.7), then the cross section of dust in the disk is A{sub d} {approx_equal} 2 x 10{sup 20} km{sup 2} and its mass is M{sub d} {approx_equal} 11 lunar masses. In this case, the planetesimal disk's dust-production rate is quite heavy, M-dot {sub d{approx}}9 M {sub +} Myr{sup -1}, implying that there is or was a substantial amount of planetesimal mass there, at least 110 Earth masses. If the dust grains are darker than assumed, then the planetesimal disk's mass-loss rate and its total mass are heavier. In fact, the apparent dearth

  14. Imaging Debris Disks with CCAT

    NASA Astrophysics Data System (ADS)

    Carpenter, John M.; Bryden, G.; Matthews, B. C.; Isella, A.; Ricci, L.; Swift, J.

    2013-01-01

    Debris disks are sustained by the collisional grinding of planetesimals down to micron-sized particles. The mechanisms by which the planetesimals are perturbed include stirring by planetary mass bodies, which interact gravitationally to sculpt the disk by scattering dust particles out of the disk, and capturing dust in mean motion resonances as particles drift inwards from Poynting-Robertson drag or as planets migrate. Thus the location of the debris dust can trace where planetesimals have formed, as well as the dynamical history of the disk. With high angular resolution and high sensitivity at submillimeter wavelengths, CCAT will be a powerful telescope to discover and image the structure of debris disks around nearby stars. This poster will describe various surveys that CCAT will conduct to search for new debris disks.

  15. Lightweight Shield Against Space Debris

    NASA Technical Reports Server (NTRS)

    Redmon, John W., Jr.; Lawson, Bobby E.; Miller, Andre E.; Cobb, W. E.

    1992-01-01

    Report presents concept for lightweight, deployable shield protecting orbiting spacecraft against meteoroids and debris, and functions as barrier to conductive and radiative losses of heat. Shield made in four segments providing 360 degree coverage of cylindrical space-station module.

  16. Lightweight Shield Against Space Debris

    NASA Technical Reports Server (NTRS)

    Redmon, John W., Jr.; Lawson, Bobby E.; Miller, Andre E.; Cobb, W. E.

    1992-01-01

    Report presents concept for lightweight, deployable shield protecting orbiting spacecraft against meteoroids and debris, and functions as barrier to conductive and radiative losses of heat. Shield made in four segments providing 360 degree coverage of cylindrical space-station module.

  17. NASA Orbital Debris Baseline Populations

    NASA Technical Reports Server (NTRS)

    Krisko, Paula H.; Vavrin, A. B.

    2013-01-01

    The NASA Orbital Debris Program Office has created high fidelity populations of the debris environment. The populations include objects of 1 cm and larger in Low Earth Orbit through Geosynchronous Transfer Orbit. They were designed for the purpose of assisting debris researchers and sensor developers in planning and testing. This environment is derived directly from the newest ORDEM model populations which include a background derived from LEGEND, as well as specific events such as the Chinese ASAT test, the Iridium 33/Cosmos 2251 accidental collision, the RORSAT sodium-potassium droplet releases, and other miscellaneous events. It is the most realistic ODPO debris population to date. In this paper we present the populations in chart form. We describe derivations of the background population and the specific populations added on. We validate our 1 cm and larger Low Earth Orbit population against SSN, Haystack, and HAX radar measurements.

  18. Hydraulic System Wear Debris Analysis.

    DTIC Science & Technology

    1982-08-03

    drawn. Each one-=L sample was drawn with a clean plastic pipette of one-mL capacity. The samples were placed in clean Ferrogram preparation bottles ...and from cavities in a block which held linear seals into sampling bottles . Several photographs of this debris , which was deposited on Ferro- grams...silicon in the glass overshadowed the elements of the wear debris . To overcome this difficulty, the Ferrogram should be pre- pared on a carbon-filled

  19. DebriSat Laboratory Analyses

    DTIC Science & Technology

    2015-01-05

    thomas.huynh@us.af.mil Jesse Edwards SMC/ENC jesse.edwards.4@us.af.mil J.-C. Liou NASA-JSC jer -chyi.l iou-1 @nasa.gov John Opiela NASA-JSC...DebriSat Team Members: J.-C. Liou : NASA Space Debris Program Office, NASA JSC AEDC Range G Light Gas Gun Staff Charles Griffice: Aerospace Marlon

  20. Backwater development by woody debris

    NASA Astrophysics Data System (ADS)

    Geertsema, Tjitske; Torfs, Paul; Teuling, Ryan; Hoitink, Ton

    2017-04-01

    Placement of woody debris is a common method for increasing ecological values in river and stream restoration, and is thus widely used in natural environments. Water managers, however, are afraid to introduce wood in channels draining agricultural and urban areas. Upstream, it may create backwater, depending on hydrodynamic characteristics including the obstruction ratio, the Froude number and the surface level gradient. Patches of wood may trigger or counter morphological activity, both laterally, through bank erosion and protection, and vertically, with pool and riffle formation. Also, a permeable construction composed of wood will weather over time. Both morphodynamic activity and weathering cause backwater effects to change in time. The purpose of this study is to quantify the time development of backwater effects caused by woody debris. Hourly water levels gauged upstream and downstream of patches and discharge are collected for five streams in the Netherlands. The water level drop over the woody debris patch relates to discharge in the streams. This relation is characterized by an increasing water level difference for an increasing discharge, up to a maximum. If the discharge increases beyond this level, the water level difference reduces to the value that may represent the situation without woody debris. This reduction depends primarily on the obstruction ratio of the woody debris in the channel cross-section. Morphologic adjustments in the stream and reorientation of the woody material reduce the water level drop over the patches in time. Our results demonstrate that backwater effects can be reduced by optimizing the location where woody debris is placed and manipulating the obstruction ratio. Current efforts are focussed on representing woody debris in a one-dimensional numerical model, aiming to obtain a generic tool to achieve a stream design with woody debris that minimizes backwater.

  1. Optimizing Orbital Debris Monitoring with Optical Telescopes

    DTIC Science & Technology

    2010-09-01

    Continued growth in the orbital debris population has renewed concerns over the long-term use of space. Debris poses an increasing risk to manned...in a catalog. Passive optical systems hold great promise to provide a cost-effective means to monitor orbital debris . Recent advances in optical...non-tracking mode for uncued debris detection. The governing radiometric equations for sensing orbital debris are developed, illustrating the

  2. Decision time on orbital debris

    NASA Technical Reports Server (NTRS)

    Loftus, Joseph P.; Tilton, Lee E.; Temple, L. Parker, III

    1988-01-01

    The problem of orbital debris, especially in LEO is discussed, stressing ways to minimize hazards caused by debris. There are over 7,000 objects making up 2.4 X 10 to the 6th kg of debris in LEO with velocities up to 7 km/sec. The least costly way of minimizing hazards from debris is to make spent rocket stages inert, to preclude failures after their useful life, by insuring that all residual propellants and pressurant gases are vented while the stage is still subject to command. A more costly option is the actively controlled deorbit of spent stages and spacecraft at the end of their useful mission life. The removal of inert stages or spacecraft is too costly to be practical. The least expensive methods of removal are deorbit for altitudes below 25,000 km and placing the object in earth-escape trajectory for objects at higher altitudes. NASA is developing a special radar to measure the existing small-particle debris and its changes over time, and international agreements are expected to set standards of operational practices to minimize debris.

  3. Plastic debris straps on threatened blue shark Prionace glauca.

    PubMed

    Colmenero, Ana I; Barría, Claudio; Broglio, Elisabetta; García-Barcelona, Salvador

    2017-02-15

    Juveniles of blue shark Prionace glauca caught in pelagic longlines targeting tuna and swordfish in the Atlantic Ocean and the Mediterranean Sea were found entangled with plastic straps around their gill region. The plastic debris were identified as strapping bands and caused several degrees of injuries on the dorsal musculature and pectoral fins. They were also obstructing the gill slits probably causing breathing issues. These records were uploaded in the web site seawatchers.org, and highlight the potential of citizen science in revealing the occurrence of such problems which could help to measure the effects of plastic debris on marine life. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Debris Dams, Sediment Impoundment, and the Relief of Headwater Streams

    NASA Astrophysics Data System (ADS)

    Lancaster, S. T.; Grant, G. E.

    2004-12-01

    In forested, mountain landscapes where debris flows are common, valley-spanning debris dams formed by debris-flow deposition are a common feature of headwater valleys. In this paper, the effects of debris dams on the evolution of headwater valley profiles over geologic time are examined. The main channels of three small (approximately 2 sq. km) watersheds in the Oregon Coast Range, USA, were surveyed, with special care given to capturing the relief of each significant step and noting the step-forming agent, whether wood, boulders, a complex mixture of the two, or bedrock (although the last is not treated herein). Channel and valley widths were also measured, and surface bed material measurements (pebble counts) were taken at one of the sites. The amount of relief in wood and/or boulder steps is highly variable within and among sites, reaching a maximum of 58% at one location. The surveyed steps comprise 9.8%, 19%, and 6.4% of total basin relief in the three sites, respectively. A model of valley profile evolution is derived that accounts for the facts that (a) only a fraction of the valley width is occupied by the channel at any given time and (b) bedrock is often shielded from erosion by sediment impounded behind debris dams. Under the assumption of steady-state incision, the equation for incision rate is solved for valley gradient as a function of contributing area, parameter values are estimated or supplied by field data, and the results are compared to plots of gradient vs. contributing area for the field sites. These comparisons suggest--but do not demonstrate--a strong effect of network structure, which varies significantly among the sites, on profile shape and relief because of the different susceptibilities to debris-flow deposition and, therefore, debris-dam formation. Specifically, in a reach where the ratio of step height to spacing drops abruptly, stream gradient also falls more steeply in a way consistent with model predictions. Finally, for one site

  5. Magnitude and frequency data for historic debris flows in Grand Canyon National Park and vicinity, Arizona

    USGS Publications Warehouse

    Melis, T.S.; Webb, R.H.; Griffiths, P.G.; Wise, T.J.

    1995-01-01

    Debris flows occur in 529 tributaries of the Colorado River in Grand Canyon between Lees Ferry and Diamond Creek, Arizona (river miles 0 to 225). An episodic type of flash flood, debris flows transport poorly-sorted sediment ranging in size from clay to boulders into the Colorado River. Debris flows create and maintain debris fans and the hundreds of associated riffles and rapids that control the geomorphic framework of the Colorado River downstream from Glen Canyon Dam. Between 1984 and 1994, debris flows created 4 new rapids and enlarged 17 existing rapids and riffles. Debris flows in Grand Canyon are initiated by slope failures that occur during intense rainfall. Three of these mechanisms of slope failure are documented. Failures in weathered bedrock, particularly in the Hermit Shale and Supai Group, have initiated many historic debris flows in Grand Canyon. A second mechanism, termed the fire-hose effect, occurs when runoff pours over cliffs onto unconsolidated colluvial wedges, triggering a failure. A third initiation mechanism occurs when intense precipitation causes failures in colluvium overlying bedrock. Multiple source areas and extreme topographic relief in Grand Canyon commonly result in combinations of these three initiation mechanisms. Interpretation of 1,107 historical photographs spanning 120 years, supplemented with aerial photography made between 1935 and 1994, yielded information on the frequency of debris flows in 168 of the 529 tributaries (32 percent) of the Colorado River in Grand Canyon. Of the 168 tributaries, 96 contain evidence of debris flows that have occurred since 1872, whereas 72 tributaries have not had a debris flow during the last century. The oldest debris flow we have documented in Grand Canyon occurred 5,400 years ago in an unnamed tributary at river mile 63.3-R. Our results indicate that the frequency of debris flows ranges from one every 10 to 15 years in certain eastern tributaries, to less than one per century in other

  6. P300 Latency and the Development of Memory Span.

    ERIC Educational Resources Information Center

    Howard, Lawrence

    The way cognitive, event-related brain potentials (ERPs) can aid in further understanding of memory span change in children is discussed. ERPs are time-dependent changes in electrical activity of the brain (as recorded by scalp electrodes) following the presentation of a physical stimulus through auditory, visual, or somatosensory modalities. The…

  7. Interim Report of the Meteoroid and Debris Special Investigation Group

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Zook, Herbert A.; Horz, Fred; Atkinson, Dale R.; Coombs, Cassandra R.; Watts, Alan J.; Dardano, Claire B.; See, Thomas H.; Simon, Charles G.; Kinard, William H.

    1992-01-01

    The LDEF Meteoroid and Debris Special Investigation Group (hereafter M&D SIG) was formed to maximize the data harvest from LDEF by permitting the characterization of the meteoroid and space debris impact record of the entire satellite. Thus, our work is complementary to that of the various M&D PIs, all of whom are members of the SIG. This presentation will summarize recent results and discussions concerning five critical SIG goals: (1) Classification of impactors based upon composition of residues; (2) Small impact (microimpact) features; (3) Impact cratering and penetration data to derive projectile sizes and masses; (4) Particulate flux estimates in low-Earth orbit; (5) The LDEF Meteoroid and Debris database.

  8. Report of the Meteoroid and Debris Special Investigation Group

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Zook, Herbert A.; Horz, Fred; Atkinson, Dale R.; Coombs, Cassandra R.; Watts, Alan J.; Dardano, Claire B.; See, Thomas H.; Simon, Charles G.; Kinard, William H.

    1993-01-01

    The LDEF Meteoroid and Debris Special Investigation Group (hereafter M&D SIG) was formed to maximize the data harvest from LDEF by permitting the characterization of the meteoroid and space debris impact record of the entire satellite. Thus, our work is complementary to that of the various M&D PI's, all of whom are members of the SIG. This presentation will summarize recent results and discussions concerning five critical SIG goals: (1) classification of impactors based upon composition of residues, (2) small impact (microimpact) features, (3) impact cratering and penetration data to derive projectile sizes and masses, (4) particulate flux estimates in low-Earth orbit, and (5) the LDEF Meteoroid and Debris database.

  9. Ultraviolet spectroscopy of meteoric debris of comets

    NASA Technical Reports Server (NTRS)

    Wdowiak, T. J.; Kubinec, W. R.; Nuth, J. A.

    1986-01-01

    It is proposed to carry out slitless spectroscopy at ultraviolet wavelengths from orbit of meteoric debris associated with comets. The Eta Aquarid and Orionid/Halley and the Perseid/1962 862 Swift-Tuttle showers would be principal targets. Low light level, ultraviolet video technique will be used during night side of the orbit in a wide field, earthward viewing mode. Data will be stored in compact video cassette recorders. The experiment may be configured as a GAS package or in the HITCHHIKER mode. The latter would allow flexible pointing capability beyond that offered by shuttle orientation of the GAS package, and doubling of the data record. The 1100 to 3200 A spectral region should show emissions of atomic, ionic, and molecular species of interest on cometary and solar system studies.

  10. The physics of debris flows

    USGS Publications Warehouse

    Iverson, R.M.

    1997-01-01

    Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ???10 m3 of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate

  11. Space Debris Environment Remediation Concepts

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.; Klinkrad, Heiner

    2009-01-01

    Long-term projections of the space debris environment indicate that even drastic measures, such as an immediate, complete halt of launch and release activities, will not result in a stable environment of man-made space objects. Collision events between already existing space hardware will within a few decades start to dominate the debris population, and result in a net increase of the space debris population, also in size regimes which may cause further catastrophic collisions. Such a collisional cascading will ultimately lead to a run-away situation ("Kessler syndrome"), with no further possibility of human intervention. The International Academy of Astronautics (IAA) has been investigating the status and the stability of the space debris environment in several studies by first looking into space traffic management possibilities and then investigating means of mitigating the creation of space debris. In an ongoing activity, an IAA study group looks at ways of active space debris environment remediation. In contrast to the former mitigation study, the current activity concentrates on the active removal of small and large objects, such as defunct spacecraft, orbital stages, and mission-related objects, which serve as a latent mass reservoir that fuels initial catastrophic collisions and later collisional cascading. The paper will outline different mass removal concepts, e.g. based on directed energy, tethers (momentum exchange or electrodynamic), aerodynamic drag augmentation, solar sails, auxiliary propulsion units, retarding surfaces, or on-orbit capture. Apart from physical principles of the proposed concepts, their applicability to different orbital regimes, and their effectiveness concerning mass removal efficiency will be analyzed. The IAA activity on space debris environment remediation is a truly international project which involves more than 23 contributing authors from 9 different nations.

  12. Optical Observations of Space Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Abercromby, Kira; Rodriquez, Heather; Barker, Edwin S.; Kelecy, Thomas

    2008-01-01

    This viewgraph presentation reviews the use of optical telescopes to observe space debris. .It will present a brief review of how the survey is conducted, and what some of the significant results encompass. The goal is to characterize the population of debris objects at GEO, with emphasis on the faint object population. Because the survey observations extend over a very short arc (5 minutes), a full six parameter orbit can not be determined. Recently we have begun to use a second telescope, the 0.9-m at CTIO, as a chase telescope to do follow-up observations of potential GEO debris candidates found by MODEST. With a long enough sequence of observations, a full six-parameter orbit including eccentricity can be determined. The project has used STK since inception for planning observing sessions based on the distribution of bright cataloged objects and the anti-solar point (to avoid eclipse). Recently, AGI's Orbit Determination Tool Kit (ODTK) has been used to determine orbits, including the effects of solar radiation pressure. Since an unknown fraction of the faint debris at GEO has a high area-to-mass ratio (A/M), the orbits are perturbed significantly by solar radiation. The ODTK analysis results indicate that temporal variations in the solar perturbations, possibly due to debris orientation dynamics, can be estimated in the OD process. Additionally, the best results appear to be achieved when solar forces orthogonal to the object-Sun line are considered. Determining the A/M of individual objects and the distribution of A/M values of a large sample of debris is important to understanding the total population of debris at GEO

  13. Mount Baker lahars and debris flows, ancient, modern, and future

    USGS Publications Warehouse

    Tucker, David S; Scott, Kevin M.; Grossman, Eric E.; Linneman, Scott

    2014-01-01

    Holocene lahars and large debris flows (>106 m3) have left recognizable deposits in the Middle Fork Nooksack valley. A debris flow in 2013 resulting from a landslide in a Little Ice Age moraine had an estimated volume of 100,000 m3, yet affected turbidity for the entire length of the river, and produced a slug of sediment that is currently being reworked and remobilized in the river system. Deposits of smaller-volume debris flows, deposited as terraces in the upper valley, may be entirely eroded within a few years. Consequently, the geologic record of small debris flows such as those that occurred in 2013 is probably very fragmentary. Small debris flows may still have significant impacts on hydrology, biology, and human uses of rivers downstream. Impacts include the addition of waves of fine sediment to stream loads, scouring or burying salmon-spawning gravels, forcing unplanned and sudden closure of municipal water intakes, damaging or destroying trail crossings, extending river deltas into estuaries, and adding to silting of harbors near river mouths.

  14. Deriving debris-flow characteristics from vertical laser profile scanners

    NASA Astrophysics Data System (ADS)

    Jacquemart, Mylène; Felix, Morsdorf; Graf, Christoph

    2015-04-01

    Two well-known debris-flow channels in the Swiss Alps, the Dorfbach, in the community of Randa, canton of Valais and the Spreitgraben (community of Guttannen, BE) were fitted with a setup of two laser profile scanners each. Since 2011 (Randa site) and 2012 (Spreitgraben site), these devices have been scanning the passing debris flows at rates of 50 Hz or 75 Hz, recording several million across bed profiles with point densities of roughly 20 points per meter during debris-flow events. In order to comprehend the vast possibilities this extraordinary data set offers, a preliminary evaluation has been undertaken, writing code that allows for a semi-automatic extraction of the main debris-flow characteristics maximum flow height, peak discharge, total discharge as well as spatially distributed flow velocity. The analysis of 13 events, of which 12 took place at the Dorfbach site, and one took place at the Spreitgraben site, revealed that a large-scale Particle Image Velocimetry (PIV) approach can be used to derive flow velocities, and these in turn can be used to compute discharge curves for all of the recorded events. Total automation has proven to be unrealistic, because the choice of the bed geometry greatly influences discharge results. Also, excluding outlying velocity values is necessary, in order to find reliable peak discharge values. Nevertheless, we find that the laser scanners offer distinct advantages over the 'established' setup consisting of geophones and a radar gauge because the scanners catch the debris flow as it changes its flow path and offer much higher resolution in terms of distributed flow height measurements. Furthermore, the single profiles of the recorded debris flows were analyzed with regard to their surface geometry by fitting fourth order polynomials to find the points of inflection along the profiles. From this, we have been able to estimate the amount of flow height that debris flows gain by building their well-known convex fronts, and

  15. Seismological Aspects of the August 7th Zhouqu Debris Flows

    NASA Astrophysics Data System (ADS)

    Dan, Y.; Huang, X.

    2016-12-01

    Broadband seismic records have been proven to be a sufficient tool in extracting movement characteristics of debris flows in the last decades. The catastrophic Sanyanyu and Luojiayu debris flows, which were induced by a heavy rainfall, occurred at approximately the midnight of August 7th, 2010 (Beijing time, UTC+8) and claimed 1,765 lives. Broadband seismic signals recorded by the Zhouqu seismic station positioned only 150 meters away from the exit are acquired and analyzed in this study. Seismic signals reveal that the Sanyanyu debris flow started developing after a major rock collapse at approximately 23:23:50. The formation time of the Sanyanyu debris flow to separate its development stage and maturity stage was determined at 23:33:15 using spectrograms and amplitude variation patterns of seismic signals. Seismic signals, before and after the formation time, have distinctively different frequency characteristics. The frequency content of seismic signals generated by the maturity stage is more regular than that generated by the development stage. The maturity stage was further divided into five sub stages according to its amplitude variation patterns, including three increase sub stages and two stable sub stages alternately distributed. These five sub stages belong to two processes of the Sanyanyu debris flow which generate seismic signals with different frequency contents. The main frequency band of the first four sub stages continuously varies from approximately 2 - 8.5 Hz at start to approximately 3 - 9.5 Hz in the end. For the last sub stage, the upper boundary of the main frequency increases in a near linear way and reaches approximately 13 - 16 Hz in the end. Two sub stages are recognized from the satellite image of the Sanyanyu flow path, and the mean movement velocities of the Sanyanyu debris flow during these two sub stages are estimated to be 9.2 m/s and 9.7 m/s respectively.

  16. Adaptive optics for laser space debris removal

    NASA Astrophysics Data System (ADS)

    Bennet, Francis; Conan, Rodolphe; D'Orgeville, Celine; Dawson, Murray; Paulin, Nicolas; Price, Ian; Rigaut, Francois; Ritchie, Ian; Smith, Craig; Uhlendorf, Kristina

    2012-07-01

    Space debris in low Earth orbit below 1500km is becoming an increasing threat to satellites and spacecrafts. Radar and laser tracking are currently used to monitor the orbits of thousands of space debris and active satellites are able to use this information to manoeuvre out of the way of a predicted collision. However, many satellites are not able to manoeuvre and debris-on debris collisions are becoming a signicant contributor to the growing space debris population. The removal of the space debris from orbit is the preferred and more denitive solution. Space debris removal may be achieved through laser ablation, whereby a high power laser corrected with an adaptive optics system could, in theory, allow ablation of the debris surface and so impart a remote thrust on the targeted object. The goal of this is to avoid collisions between space debris to prevent an exponential increase in the number of space debris objects. We are developing an experiment to demonstrate the feasibility of laser ablation for space debris removal. This laser ablation demonstrator utilises a pulsed sodium laser to probe the atmosphere ahead of the space debris and the sun re ection of the space debris is used to provide atmospheric tip{tilt information. A deformable mirror is then shaped to correct an infrared laser beam on the uplink path to the debris. We present here the design and the expected performance of the system.

  17. Controls on sediment transfer and storage on debris flow fans

    NASA Astrophysics Data System (ADS)

    Schürch, Peter; Densmore, Alexander L.; Rosser, Nick J.; McArdell, Brian W.

    2010-05-01

    Debris flows are important in transporting sediment from mountain slopes to valley floors. Debris flow fans are regarded as sediment traps, but often little is known about what proportion of the input at the fan apex is stored on the fan (the fan efficiency, ef) or how individual debris flow volumes evolve via entrainment and deposition along the flow path. It is therefore crucial to investigate the controls on debris flow volume change along the whole flow path in order to understand the role that debris flows play within the integrated sediment routing system. We present high spatial resolution data on the volume change of debris flows due to entrainment and deposition on the Illgraben fan, Switzerland. This fan has experienced 36 debris flows since June 2000, generally in response to summer (May-October) convective storms. We compare debris flow hydrographs from fan apex and fan toe with locally measured lag rates from terrestrial laser scanning (TLS) of a 300 m study reach for several of these events. Debris flow volumes are calculated from hydrographs measured by radar sensors, and flow velocity estimates are based on geophone measurements of flow front position. The debris flow lag rate is defined as the volume change per unit channel length. We present high-resolution (0.2 m grid) change maps from successive sets of TLS topographic data along the study reach. We use the change maps to derive reach-scale lag rates of single debris flow events by projecting the volume change onto a flow axis down the channel thalweg. We use video recordings of the flow fronts and recordings of geophones and radar sensors to investigate flow properties in two locations along the flow path. The flow hydrograph data show that flow volumes can change by up to one order of magnitude between fan apex and fan toe. Both increasing and decreasing flow volumes are observed in different events moving through the same channel. Lag rates measured in the study reach with TLS data are

  18. Initiation of Recent Debris Flows on Mount Rainier, Washington: A Climate Warming Signal?

    NASA Astrophysics Data System (ADS)

    Copeland, E. A.; Kennard, P.; Nolin, A. W.; Lancaster, S. T.; Grant, G. E.

    2008-12-01

    The first week of November 2006 an intense rainstorm inundated the Pacific Northwest and triggered debris flows on many large volcanoes in the Cascade Range of Washington and Oregon. At Mount Rainier, Washington, 45.7 cm of rain was recorded in 36 hours; the storm was preceded by a week of light precipitation and moderate temperatures, so that rain fell on nearly-saturated ground with minimal snow cover. The November 2006 storm was exceptional in that it resulted in a 100-year flood and caused an unprecedented six-month closure of Mount Rainier National Park. It also focused inquiry as to whether debris flows from Cascade volcanoes are likely to occur more frequently in the future as glaciers recede due to climate warming, leaving unstable moraines and sediment that can act as initiation sites. We examined the recent history of debris flows from Mount Rainier using aerial photographs and field surveyed debris flow tracks. Prior to 2001, debris flows were recorded in association with rainfall or glacial outburst floods in 4 drainages, but 3 additional drainages were first impacted by debris flows in 2001, 2005, and 2006, respectively. We discovered that most of the recent debris flows initiated as small gullies in unconsolidated material at the edge of fragmented glaciers or areas of permanent snow and ice. Other initiation sites occur on steep-sided un-vegetated moraines. Of the 28 named glaciers on Mount Rainier, debris flows initiated near five glaciers in the exceptional storm of 2006 (Winthrop, Inter, Kautz-Success, Van Trump, Pyramid, and South Tahoma). Less exceptional storms, however, have also produced wide-spread debris flows: in September 2005, 15.3 cm of rain fell in 48 hours on minimal snow cover and caused debris flows in all except 2 of the glacier drainages that initiated in 2006. Debris flows from both storms initiated at elevations of 1980 to 2400 m, traveled 5 to 10 kilometers, and caused significant streambed aggradation. These results suggest a

  19. Biological response to prosthetic debris

    PubMed Central

    Bitar, Diana; Parvizi, Javad

    2015-01-01

    Joint arthroplasty had revolutionized the outcome of orthopaedic surgery. Extensive and collaborative work of many innovator surgeons had led to the development of durable bearing surfaces, yet no single material is considered absolutely perfect. Generation of wear debris from any part of the prosthesis is unavoidable. Implant loosening secondary to osteolysis is the most common mode of failure of arthroplasty. Osteolysis is the resultant of complex contribution of the generated wear debris and the mechanical instability of the prosthetic components. Roughly speaking, all orthopedic biomaterials may induce a universal biologic host response to generated wear débris with little specific characteristics for each material; but some debris has been shown to be more cytotoxic than others. Prosthetic wear debris induces an extensive biological cascade of adverse cellular responses, where macrophages are the main cellular type involved in this hostile inflammatory process. Macrophages cause osteolysis indirectly by releasing numerous chemotactic inflammatory mediators, and directly by resorbing bone with their membrane microstructures. The bio-reactivity of wear particles depends on two major elements: particle characteristics (size, concentration and composition) and host characteristics. While any particle type may enhance hostile cellular reaction, cytological examination demonstrated that more than 70% of the debris burden is constituted of polyethylene particles. Comprehensive understanding of the intricate process of osteolysis is of utmost importance for future development of therapeutic modalities that may delay or prevent the disease progression. PMID:25793158

  20. Space Telescopes and Orbital Debris

    NASA Astrophysics Data System (ADS)

    Seitzer, Patrick

    2009-01-01

    Almost 12,000 artificial objects orbiting the Earth are currently in the public catalog of orbital elements maintained by the USAF. Only a small fraction of them are operational satellites. The remainder is satellites whose missions have ended, rocket bodies, and parts and debris from larger parent objects. And the catalog only contains the biggest and brightest of the objects in orbit. The Low Earth Orbit (LEO) regime where most of this population concentrates is also a regime of incredible interest to astronomers, since it is where flagship missions such as the Hubble Space Telescope and other Great Observatories operate. I'll review the current state of knowledge of the orbital debris population, how it has grown with time, and how this environment could affect current and future space telescopes. There are mitigation measures which many spacecraft operators have adopted which can control the growth of the debris population. Orbital debris research at the University of Michigan is funded by NASA's Orbital Debris Program Office, Johnson Space Center, Houston, Texas.

  1. Modeling UHMWPE wear debris generation.

    PubMed

    Baudriller, H; Chabrand, P; Moukoko, D

    2007-02-01

    It is widely recognized that polyethylene wear debris is one of the main causes of long-term prosthesis loosening. The noxious bioreactivity associated with this debris is determined by its size, shape, and quantity. The aim of this study was to develop a numerical tool that can be used to investigate the primary polyethylene wear mechanisms involved. This model illustrates the formation of varying flow of polyethylene debris with various shapes and sizes caused by elementary mechanical processes. Instead of using the classical continuum mechanics formulation for this purpose, we used a divided materials approach to simulate debris production and release. This approach involves complex nonlinear bulk behaviors, frictional adhesive contact, and characterizes material damage as a loss of adhesion. All the associated models were validated with various benchmark tests. The examples given show the ability of the numerical model to generate debris of various shapes and sizes such as those observed in implant retrieval studies. Most of wear mechanisms such as abrasion, adhesion, and the shearing off of micro-asperities can be described using this approach. Furthermore, it could be applied to study the effects of friction couples, macroscopic geometries, and material processing (e.g. irradiation) on wear. (c) 2006 Wiley Periodicals, Inc.

  2. Hydroplaning and submarine debris flows

    NASA Astrophysics Data System (ADS)

    de Blasio, Fabio V.; Engvik, Lars; Harbitz, Carl B.; ElverhøI, Anders

    2004-01-01

    Examination of submarine clastic deposits along the continental margins reveals the remnants of holocenic or older debris flows with run-out distances up to hundreds of kilometers. Laboratory experiments on subaqueous debris flows, where typically one tenth of a cubic meter of material is dropped down a flume, also show high velocities and long run-out distances compared to subaerial debris flows. Moreover, they show the tendency of the head of the flow to run out ahead of the rest of the body. The experiments reveal the possible clue to the mechanism of long run-out. This mechanism, called hydroplaning, begins as the dynamic pressure at the front of the debris flow becomes of the order of the pressure exerted by the weight of the sediment. In such conditions a layer of water can intrude under the sediment with a lubrication effect and a decrease in the resistance forces between the sediment and the seabed. A physical-mathematical model of hydroplaning is presented and investigated numerically. The model is applied to both laboratory- and field-scale debris flows. Agreement with laboratory experiments makes us confident in the extrapolation of our model to natural flows and shows that long run-out distances can be naturally attained.

  3. Geosynchronous Earth orbital debris campaign

    NASA Astrophysics Data System (ADS)

    Africano, John L.; Sydney, Paul F.; Talent, David L.; Stansbery, Eugene G.; Jarvis, Kandy S.; Monet, David G.; Seitzer, Patrick

    2000-10-01

    The National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) is conducting systematic searches of the Geosynchronous Earth Orbit (GEO) environment as part of an international measurement campaign under the auspices of the Inter-Agency Space Debris Coordination Committee (IADC). The objectives for this survey are to determine the extent and character of debris in GEO, buy obtaining distributions for the brightness, inclination, Right Ascension of Ascending Node (RAAN), and mean motion of the debris. The Charged Coupled Device (CCD) Debris Telescope (CDT), an automated 0.32 meter aperture, transportable Schmidt telescope presently located at Cloudcroft, New Mexico, is used nightly to monitor the GEO debris environment. The CDT is equipped with a CCD camera capable of detecting 17th magnitude objects in a 20 second exposure. This corresponds to a 0.6 meter diameter object having a 0.2 albedo at 36000 km. Two other larger telescopes have been used for this purpose, the United States Naval Observatory's new 1.3 meter telescope located in Flagstaff Arizona and a 0.6 m Schmidt telescope located at Cerro Tololo Inter-American Observatory (CTIO) near La Serena Chile. Data reduction and analysis software used to reduce this data exploit tools developed by both the astronomical and DoD communities. These tools and data results are presented.

  4. Optical surveys for space debris

    NASA Astrophysics Data System (ADS)

    Schildknecht, Thomas

    2007-01-01

    Space debris—man-made non-functional objects of all sizes in near-Earth space—has been recognized as an increasing threat for current and future space operations. The debris population in near-Earth space has therefore been extensively studied during the last decade. Information on objects at altitudes higher than about 2,000 km is, however, still comparatively sparse. Debris in this region is best detected by surveys utilizing optical telescopes. Moreover, the instruments and the applied observation techniques, as well as the processing methods, have many similarities with those used in optical surveys for ‘astronomical’ objects like near-Earth objects (NEOs). The present article gives a general introduction to the problem of space debris, presents the used observation and processing techniques emphasizing the similarities and differences compared to optical surveys for NEOs, and reviews the results from optical surveys for space debris in high-altitude Earth orbits. Predictions on the influence of space debris on the future of space research and space astronomy in particular are reported as well.

  5. Development of the perceptual span in reading: A longitudinal study.

    PubMed

    Sperlich, Anja; Meixner, Johannes; Laubrock, Jochen

    2016-06-01

    The perceptual span is a standard measure of parafoveal processing, which is considered highly important for efficient reading. Is the perceptual span a stable indicator of reading performance? What drives its development? Do initially slower and faster readers converge or diverge over development? Here we present the first longitudinal data on the development of the perceptual span in elementary school children. Using the moving window technique, eye movements of 127 German children in three age groups (Grades 1, 2, and 3 in Year 1) were recorded at two time points (T1 and T2) 1 year apart. Introducing a new measure of the perceptual span, nonlinear mixed-effects modeling was used to separate window size effects from asymptotic reading performance. Cross-sectional differences were well replicated longitudinally. Asymptotic reading rate increased monotonously with grade, but in a decelerating fashion. A significant change in the perceptual span was observed only between Grades 2 and 3. Together with results from a cross-lagged panel model, this suggests that the perceptual span increases as a consequence of relatively well-established word reading. Stabilities of observed and predicted reading rates were high after Grade 1, whereas the perceptual span was only moderately stable for all grades. Comparing faster and slower readers as assessed at T1, in general, a pattern of stable between-group differences emerged rather than a compensatory pattern; second and third graders even showed a Matthew effect in reading rate and the perceptual span, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Homological Computation Using Spanning Trees

    NASA Astrophysics Data System (ADS)

    Molina-Abril, H.; Real, P.

    We introduce here a new mathbb{F}_2 homology computation algorithm based on a generalization of the spanning tree technique on a finite 3-dimensional cell complex K embedded in ℝ3. We demonstrate that the complexity of this algorithm is linear in the number of cells. In fact, this process computes an algebraic map φ over K, called homology gradient vector field (HGVF), from which it is possible to infer in a straightforward manner homological information like Euler characteristic, relative homology groups, representative cycles for homology generators, topological skeletons, Reeb graphs, cohomology algebra, higher (co)homology operations, etc. This process can be generalized to others coefficients, including the integers, and to higher dimension.

  7. Ingestion and defecation of marine debris by loggerhead sea turtles, Caretta caretta, from by-catches in the South-West Indian Ocean.

    PubMed

    Hoarau, Ludovic; Ainley, Lara; Jean, Claire; Ciccione, Stéphane

    2014-07-15

    Marine debris, caused by anthropogenic pollution, is a major problem impacting marine wildlife worldwide. This study documents and quantifies the ingestion and defecation of debris by 74 loggerhead sea turtles, Caretta caretta, in the South-West Indian Ocean. Debris was found in 51.4% of gut or fecal samples of loggerheads by-catch from Reunion Island long liners. Anthropogenic debris was ubiquitous in our samples with plastics accounting for 96.2% of the total debris collected. No significant relationship was detected between the characteristics of ingested debris and the biometric characteristics of loggerheads. The number, weight, volume and mean length of debris were higher in gut content of deceased loggerheads than in fecal samples of live turtles, but not significantly, except for the mean length. This is the first record of debris ingestion by sea turtles in the Indian Ocean and our results highlight the magnitude of this pollution of the marine environment.

  8. Adaptive prolonged postreproductive life span in killer whales.

    PubMed

    Foster, Emma A; Franks, Daniel W; Mazzi, Sonia; Darden, Safi K; Balcomb, Ken C; Ford, John K B; Croft, Darren P

    2012-09-14

    Prolonged life after reproduction is difficult to explain evolutionarily unless it arises as a physiological side effect of increased longevity or it benefits related individuals (i.e., increases inclusive fitness). There is little evidence that postreproductive life spans are adaptive in nonhuman animals. By using multigenerational records for two killer whale (Orcinus orca) populations in which females can live for decades after their final parturition, we show that postreproductive mothers increase the survival of offspring, particularly their older male offspring. This finding may explain why female killer whales have evolved the longest postreproductive life span of all nonhuman animals.

  9. Summary of Orbital Debris Workshop

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.

    1982-01-01

    An Orbital Debris Workshop was conducted in July 1982. The working groups established were related to measurements of large particles, modeling of large particles, measurements of small particles, spacecraft hazard and shielding requirements, and space object management. The results of the Orbital Debris Workshop reaffirm the need for research to better understand the character of orbital debris, its effects on future spacecraft, and the related requirements for policy. A clear charter is required for this research to receive the necessary support, focus, and coordination. It was recommended that NASA assume the role of lead agency. The first task is to develop an overall plan with both Department of Defense and the North American Aerospace Defense Command participation.

  10. Atomic gas in debris discs

    NASA Astrophysics Data System (ADS)

    Hales, Antonio S.; Barlow, M. J.; Crawford, I. A.; Casassus, S.

    2017-04-01

    We have conducted a search for optical circumstellar absorption lines in the spectra of 16 debris disc host stars. None of the stars in our sample showed signs of emission line activity in either Hα, Ca II or Na I, confirming their more evolved nature. Four stars were found to exhibit narrow absorption features near the cores of the photospheric Ca II and Na I D lines (when Na I D data were available). We analyse the characteristics of these spectral features to determine whether they are of circumstellar or interstellar origins. The strongest evidence for circumstellar gas is seen in the spectrum of HD 110058, which is known to host a debris disc observed close to edge-on. This is consistent with a recent ALMA detection of molecular gas in this debris disc, which shows many similarities to the β Pictoris system.

  11. Thirty-one years of debris-flow observation and monitoring near La Honda, California, USA

    USGS Publications Warehouse

    Wieczorek, G.F.; Wilson, R.C.; Ellen, S.D.; Reid, M.E.; Jayko, A.S.

    2007-01-01

    From 1975 until 2006,18 intense storms triggered at least 248 debris flows within 10 km2 northwest of the town of La Honda within the Santa Cruz Mountains, California. In addition to mapping debris flows and other types of landslides, studies included soil sampling and geologic mapping, piezometric and tensiometer monitoring, and rainfall measurement and recording. From 1985 until 1995, a system with radio telemetered rain gages and piezometers within the La Honda region was used for issuing six debris-flow warnings within the San Francisco Bay region through the NOAA ALERT system. Depending upon the relative intensity of rainfall during storms, debris flows were generated from deep slumps, shallow slumps, shallow slides in colluvium and shallow slides over bedrock. Analysis shows the storms with abundant antecedent rainfall followed by several days of steady heavy intense rainfall triggered the most abundant debris flows. ?? 2007 millpress.

  12. Life-Span Learning: A Developmental Perspective

    ERIC Educational Resources Information Center

    Thornton, James E.

    2003-01-01

    The article discusses learning as embedded processes of development and aging, and as social activity over the life course. The concept of life-span learning is proposed and outlined to discuss these processes as aspects of and propositions in life-span development and aging theory. Life-span learning processes arise and continuously develop in a…

  13. C-SPAN Networks: Professors' Guide.

    ERIC Educational Resources Information Center

    C-SPAN in the Classroom, 1993

    1993-01-01

    The intention of this guide is to serve as a forum for college faculty members to share ideas and articles about using C-SPAN programming in college classrooms and in academic research. The first article, "C-SPAN as a 'Lecture Launcher'" (Stephen Frantzich) illustrates how well-chosen segments of C-SPAN programming can be used to…

  14. Rainfall Generated Debris flows on Mount Shasta: July 21, 2015

    NASA Astrophysics Data System (ADS)

    Mikulovsky, R. P.; De La Fuente, J. A.; Courtney, A.; Bachmann, S.; Rodriguez, H.; Rust, B.; Schneider, F.; Veich, D.

    2015-12-01

    Convective storms on the evening of July 21, 2015 generated a number of debris flows on the SE flank of Mount Shasta Volcano, Shasta-Trinity National Forest. Widespread rilling, gullying and sheet erosion occurred throughout the affected area. These storms damaged roads by scouring drainage ditches, blocking culverts, eroding road prisms, and depositing debris where streams emerged from their incised channels and flowed over their alluvial fans. Effects were limited geographically to a narrow band about 6 miles wide trending in a northeasterly direction. Debris flows were identified at Pilgrim Creek and nearby channels, and Mud Creek appears to have experienced sediment laden flows rather than debris flows. Doppler radar data reveal that the storm cells remained nearly stationary for two hours before moving in a northeasterly direction. Debris flows triggered by convective storms occur often at Mount Shasta, with a similar event recorded in 2003 and a larger one in 1935, which also involved glacial melt. The 1935 debris flow at Whitney Creek buried Highway 97 north of Weed, CA, and took out the railroad above the highway. In September, 2014, a large debris flow occurred in Mud Creek, but it was associated solely with glacial melt and was not accompanied by rain. The 2014 event at Mud Creek filled the channel and parts of the floodplain with debris. This debris was in turn reworked and eroded by sediment laden flows on July 21, 2015. This study was initiated in August, 2015, and began with field inventories to identify storm effects. Lidar data will be used to identify possible avulsion points that could result in unexpected flash flooding outside of the main Mud Creek channel and on adjacent streams. The results of this study will provide critical information that can be used to assess flash flood risk and better understand how to manage those risks. Finally, some conclusions may be drawn on the kinds of warning systems that may be appropriate for possible flash

  15. Space Debris Environent Remediation Concepts

    NASA Astrophysics Data System (ADS)

    Klinkrad, H.; Johnson, N. L.

    2009-03-01

    Long-term projections of the space debris environment indicate that even drastic measures, such as an immediate, complete halt of launch and release activities, will not result in a stable environment of man-made space objects. Collision events between already existing space hardware will within a few decades start to dominate the debris population, and result in a net increase of the space debris population, also at sizes which may cause further catastrophic collisions. A collisional cascading may ultimately lead to a run-away situation ("Kessler syndrome"), with no further possibility of human intervention.The International Academy of Astronautics (IAA) has been investigating the status and the stability of the space debris environment in several studies by first looking into space traffic management possibilities, and then investigating means of mitigating the creation of space debris. In an on-going activity, an IAA study group looks into methods of active space debris environment remediation. In contrast to the former mitigation study, the current activity concentrates on the active removal of large objects, such as defunct spacecraft, orbital stages, and mission-related objects, which serve as a latent mass reservoir that fuels initial castastrophic collisions and later collisional cascading. The paper will outline different mass removal concepts, e.g. based on directed energy, tethers (momentum exchange or electro-dynamic), aerodynamic drag augmentation, solar sails, auxiliary propulsion units, retarding surfaces, or on-orbit capture. Apart from physical principles of the proposed concepts, their applicability to different orbital regimes, and their effectiveness concerning mass removal efficiency will be discussed.

  16. Looking inside a debris flow

    NASA Astrophysics Data System (ADS)

    Bowman, Elisabeth; Sanvitale, Nicoletta; Bird, Joshua

    2014-05-01

    Debris flows, masses of saturated, channelized, granular materials that flow at high speeds downslope, present a hazard to lives and infrastructure in regions of high relief and runoff. They also present a challenge to modelling due to the heterogeneous, multi-phase, nature of the constituent materials, with particles ranging from boulder-size to silt-size and fluid viscosity being altered by the presence of fine particles and clay. As a debris flow travels on its flow path, it will tend to segregate, with larger particles being focused to the flow front and fluid being concentrated in the tail - resulting in different rheological behaviour in time and space. It will also tend to erode and deposit material as it moves through different channel segments or reaches, with this behaviour influenced by the confinement of the channel and the angle of the slope within each reach. Flume studies offer the potential to examine in detail the behaviour of model debris flows within the penultimate and final (deposit fan area) reaches - zones which are generally of most interest in terms of human risk. Flume studies which are conducted using transparent debris offer additional benefits to more traditional methods that use opaque materials, enabling insights to the flow behaviour that are inaccessible via other physical methods. We present flume model work which has been designed to capture some essential aspects of debris flow behaviour using well graded (polydisperse) transparent debris, albeit at reduced scale. These aspects include the final deposit spread or runout increasing for a lower concentration of solids and a higher penultimate reach slope angle, and observable particle size segregation during downslope motion. We present time-varying measurements made internally and externally at a point in the channel via Plane Laser Induced Fluorescence and Particle Image Velocimetry, PIV. The measurements enable velocity distributions of the segregating flows over time to be

  17. Control works in debris-flow channels: influence on morphology and sediment transfer

    NASA Astrophysics Data System (ADS)

    Marchi, L.

    2012-04-01

    Extensive torrent control works, such as grade-control dams, debris basins, deflecting walls, etc. have been implemented in the European Alps since the last decades of 19th century. These structural measures, aimed at stabilizing channels and to control sediment transport, are also widespread in Japan and are increasingly present in other mountain regions. As debris flows are one of the most destructive processes in steep mountain channels, hydraulic works are often intended to attenuate debris-flow hazard. Multi-temporal aerial photos and historic records permit evaluating the long term effects of torrent control works on the morphological settings of the channels and the delivery of sediment. The experience arising from over one century of torrent control works in debris-flow channels of the Alps permits also to improve the management of steep headwater catchments. A basic issue in the management of debris-flow channels is the recognition of success versus failure of engineering control works. Successful debris-flow control works provide benchmarks for further implementations, whereas the failure in reducing debris-flow hazard may lead to refinements in planning and design of control works or to the choice of preferring non-structural measures for coping with debris flows. Data from historical archives on debris-flow occurrence and on the performance of control works are the basic sources of information for these analyses. Moreover, when dealing with hydraulic structures for debris-flow control, it should be reminded that the artificial morphology resulting from the construction of check dams provides only a temporary stability to the channel and adjacent banks. This stresses the importance of evaluating the state of conservation and the effectiveness of control works and implies the need for their careful and continuous maintenance. Inventories of hydraulic structures, coupled with detailed data on catchment and channel topography, sediment sources and supply

  18. January | 201span>6 | Space Station | Page 2

    NASA Website

    Posted on January 7, 201span>6 at 12:00 pm by Mark Garcia. 1 Reply. ... August 201span>6; July 201span>6; June 201span>6; May 201span>6; April 201span>6; March 201span>6; February 201span>6; ...

  19. DebriSat Project Update and Planning

    NASA Technical Reports Server (NTRS)

    Sorge, M.; Krisko, P. H.

    2016-01-01

    DebriSat Reporting Topics: DebriSat Fragment Analysis Calendar; Near-term Fragment Extraction Strategy; Fragment Characterization and Database; HVI (High-Velocity Impact) Considerations; Requirements Document.

  20. Physical Properties of Supraglacial Debris on Mars

    NASA Astrophysics Data System (ADS)

    Baker, D. M. H.; Carter, L. M.

    2016-09-01

    The thickness and physical properties of surface debris preserving glacial ice in the mid-latitudes of Mars is assessed using crater morphology and radar sounding data. We suggest that this debris layer is much thicker than has been hypothesized.

  1. NASA Orbital Debris Requirements and Best Practices

    NASA Technical Reports Server (NTRS)

    Hull, Scott

    2014-01-01

    Limitation of orbital debris accumulation is an international and national concern, reflectedin NASA debris limitation requirements. These requirements will be reviewed, along with some practices that can be employed to achieve the requirements.

  2. What is the velocity profile of debris flows?

    NASA Astrophysics Data System (ADS)

    Walter, Fabian; McArdell, Brian

    2015-04-01

    cross-correlation scheme after calculating the signal envelope and low pass filtering it. In this sense, we do not target individual particle impacts. Rather, we measure debris flow velocities by tracking activity bursts across sensor triplets sharing the same height. Our method is therefore ideally applied to debris flows, whose geophone records show long-term modulations of signal amplitudes. For certain debris flow records our procedure provides vertical flow velocity profiles. We compare these with independent measurements of debris flow front speeds and flow depths. Furthermore, we discuss important limitations of the shear wall set up. Specifically, the channel bed below the instruments is erodible and thus varying with time. Moreover, debris deposits near the channel wall may locally perturb the debris flow and thus divert it from the direction parallel to the channel centerline. Nevertheless, we believe that our vertical flow profile results are the first of their kind and shed light on the interior of a debris flow, which is usually shielded from direct observations.

  3. Space Debris: Its Causes and Management

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2002-01-01

    Orbital debris is internationally recognized as an environmental issue which needs to be addressed today to preserve near-Earth space for future generations. All major space agencies are committed to mitigating the growth of the debris environment. Many commercial space system operators have responded positively to orbital debris mitigation principles and recommendations. Orbital debris mitigation measures are most cost-effective if included in the design development phase.

  4. A Search for Optically Faint GEO Debris

    DTIC Science & Technology

    2011-09-01

    similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American...Examples are the results from the European Space Debris Facility in the Canary Islands, MODEST (the Michigan orbital DEbris Survey Telescope at Cerro ...filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American

  5. Orbital Debris: Cost Impact on Setting Policy.

    DTIC Science & Technology

    1996-06-01

    As the exploration of space increases, the problems associated with orbital debris also increase. 0rbital debris continues to grow at a linear rate...and at worst, unusable. When mitigating orbital debris , cost and policy issues must be addressed. Currently no policy exists that makes the mitigation...of orbital debris mandatory but it only strongly recommends mitigation as long as it is cost effective. This thesis addresses the cost impact of

  6. Applying Knowledge from Terrestrial Debris-Covered Glaciers to Constrain the Evolution of Martian Debris-Covered Ice

    NASA Astrophysics Data System (ADS)

    Koutnik, M. R.; Pathare, A. V.; Todd, C.; Waddington, E.; Christian, J. E.

    2016-09-01

    We will discuss the application of terrestrial knowledge on debris emplacement, the effects of debris on glacier-surface topography, debris transport by ice flow, deformation of debris-laden ice, and atmosphere-glacier feedbacks to Mars ice.

  7. A new inventory of glaciers and supraglacial debris for the Alaska Range with a case study of rock avalanche loading

    NASA Astrophysics Data System (ADS)

    Herreid, S. J.; Arendt, A. A.; Hock, R. M.; Kienholz, C.

    2010-12-01

    Glacier area is in constant fluctuation and, to date, the only available inventory of glaciers within the Alaska Range was compiled from imagery acquired in 1948 to 1956 by the US Geological Survey. This study presents a new comprehensive inventory of Alaska Range glaciers that was digitized manually from Landsat and ASTER satellite images spanning 2004 to 2010. Glacier flow divides were derived using an automated watershed algorithm, and supraglacial debris was mapped using spectral image classification. This inventory also includes outlines of rockslide avalanche debris, as well as dates of debris deposition, when known. Variations in melt rate from supraglacial debris cover likely introduces errors when extrapolating glacier surface elevation from limited data and applying regional mass balance models. To address this problem at a location where the time of debris deposition is known, a case study of glacier response to rock avalanche loading was conducted on the West Fork Robertson Glacier during summer 2010. A rockslide avalanche with a surface area of about 1.5 km2 was deposited onto the glacier in the early 1980s. Surface ablation was measured over one month at seven sites surrounding the rockslide debris, and several boulders were surveyed to calculate glacier melt under the debris cover. In addition, ground penetrating radar measurements were taken across the rockslide to estimate debris thickness. Results from this study will help improve regional modeling and extrapolation methods for Alaska Range glaciers.

  8. Extended attention span training system

    NASA Technical Reports Server (NTRS)

    Pope, Alan T.; Bogart, Edward H.

    1991-01-01

    Attention Deficit Disorder (ADD) is a behavioral disorder characterized by the inability to sustain attention long enough to perform activities such as schoolwork or organized play. Treatments for this disorder include medication and brainwave biofeedback training. Brainwave biofeedback training systems feed back information to the trainee showing him how well he is producing the brainwave pattern that indicates attention. The Extended Attention Span Training (EAST) system takes the concept a step further by making a video game more difficult as the player's brainwaves indicate that attention is waning. The trainee can succeed at the game only by maintaining an adequate level of attention. The EAST system is a modification of a biocybernetic system that is currently being used to assess the extent to which automated flight management systems maintain pilot engagement. This biocybernetic system is a product of a program aimed at developing methods to evaluate automated flight deck designs for compatibility with human capabilities. The EAST technology can make a contribution in the fields of medical neuropsychology and neurology, where the emphasis is on cautious, conservative treatment of youngsters with attention disorders.

  9. Orbital Debris and Future Environment Remediation

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2011-01-01

    This slide presentation is an overview of the historical and current orbital debris environment. Included is information about: Projected growth of the future debris population, The need for active debris removal (ADR), A grand challenge for the 21st century and The forward path

  10. Microchemical Analysis Of Space Operation Debris

    NASA Technical Reports Server (NTRS)

    Cummings, Virginia J.; Kim, Hae Soo

    1995-01-01

    Report discusses techniques used in analyzing debris relative to space shuttle operations. Debris collected from space shuttle, expendable launch vehicles, payloads carried by space shuttle, and payloads carried by expendable launch vehicles. Optical microscopy, scanning electron microscopy with energy-dispersive spectrometry, analytical electron microscopy with wavelength-dispersive spectrometry, and X-ray diffraction chosen as techniques used in examining samples of debris.

  11. Simulations of SSLV Ascent and Debris Transport

    NASA Technical Reports Server (NTRS)

    Rogers, Stuart; Aftosmis, Michael; Murman, Scott; Chan, William; Gomez, Ray; Gomez, Ray; Vicker, Darby; Stuart, Phil

    2006-01-01

    A viewgraph presentation on Computational Fluid Dynamic (CFD) Simulation of Space Shuttle Launch Vehicle (SSLV) ascent and debris transport analysis is shown. The topics include: 1) CFD simulations of the Space Shuttle Launch Vehicle ascent; 2) Debris transport analysis; 3) Debris aerodynamic modeling; and 4) Other applications.

  12. RTF Analysis-Shuttle Debris Transport

    NASA Technical Reports Server (NTRS)

    Aftosmis, Michael

    2004-01-01

    This demo will rewew the findings of the Shuttle's Debris Transport analysis. The demo focuses on aero analysis of the entlre vehicle in ascent (orbiter, SRB and ET together at low Mach number) for debris transoort and determining maximum allowable debris sizes from various sources. We will present analysis results along with performance data of the simulation runs on Supercomputers such as Columbia.

  13. Debris flow grain size scales with sea surface temperature over glacial-interglacial timescales

    NASA Astrophysics Data System (ADS)

    D'Arcy, Mitch; Roda Boluda, Duna C.; Whittaker, Alexander C.; Araújo, João Paulo C.

    2015-04-01

    Debris flows are common erosional processes responsible for a large volume of sediment transfer across a range of landscapes from arid settings to the tropics. They are also significant natural hazards in populated areas. However, we lack a clear set of debris flow transport laws, meaning that: (i) debris flows remain largely neglected by landscape evolution models; (ii) we do not understand the sensitivity of debris flow systems to past or future climate changes; and (iii) it remains unclear how to interpret debris flow stratigraphy and sedimentology, for example whether their deposits record information about past tectonics or palaeoclimate. Here, we take a grain size approach to characterising debris flow deposits from 35 well-dated alluvial fan surfaces in Owens Valley, California. We show that the average grain sizes of these granitic debris flow sediments precisely scales with sea surface temperature throughout the entire last glacial-interglacial cycle, increasing by ~ 7 % per 1 ° C of climate warming. We compare these data with similar debris flow systems in the Mediterranean (southern Italy) and the tropics (Rio de Janeiro, Brazil), and find equivalent signals over a total temperature range of ~ 14 ° C. In each area, debris flows are largely governed by rainfall intensity during triggering storms, which is known to increase exponentially with temperature. Therefore, we suggest that these debris flow systems are transporting predictably coarser-grained sediment in warmer, stormier conditions. This implies that debris flow sedimentology is governed by discharge thresholds and may be a sensitive proxy for past changes in rainfall intensity. Our findings show that debris flows are sensitive to climate changes over short timescales (≤ 104 years) and therefore highlight the importance of integrating hillslope processes into landscape evolution models, as well as providing new observational constraints to guide this. Finally, we comment on what grain size

  14. Simulation of orbital debris impacts on bumper shields

    SciTech Connect

    Hertel, E.S. Jr.

    1992-12-31

    A series of numerical simulations have been performed using CTH to predict secondary debris formation and rear structure damage for typical bumper shields under a variety of impact geometries The simulations span a range of velocities from {approximately}3 to 12 km/s and are compared to the experiment data for the lower velocities (3 to 7 km/s). For one velocity ({approximately}7 km/s), CTH was used to demonstrate the effects of bumper thickness on secondary debris formation and rear structure damage. CTH was also used to stimulate a 12 km/s impact of a sphere on a simple Whipple bumper shield and this result will be compared to analytic damage predictions at that velocity. It has been found that CTH accurately predicts secondary debris propagation and rear damage for velocities throughout the experimentally accessible range. The CTH damage predictions at 12 km/s result in a higher ballistic limit than would be predicted from the analytic techniques.

  15. Space Debris Detection and Analysis

    DTIC Science & Technology

    1994-02-28

    7F AD-A282 012 PL.-TR-94-206 Space Debris Detection and Analysis Robert H. Eather Ron Siewert Keo Consultants 27 Irving St. Brookline MA 02146 28...PERFORMING ORGANIZATION REPORT NUMBER Keo Consultants 27 Irving St. Brookline MA 02146 9. SPONSORINGI MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING

  16. A Passive Nuclear Debris Collector.

    ERIC Educational Resources Information Center

    Griffin, John J.; And Others

    1979-01-01

    Describes a nuclear debris collector which removes trace substances from the lower atmosphere during rainfall. Suggests that the collector could be implemented into courses at various educational levels and could result in developing a network for monitoring the geographical extent of nuclear contamination. (Author/SA)

  17. A Passive Nuclear Debris Collector.

    ERIC Educational Resources Information Center

    Griffin, John J.; And Others

    1979-01-01

    Describes a nuclear debris collector which removes trace substances from the lower atmosphere during rainfall. Suggests that the collector could be implemented into courses at various educational levels and could result in developing a network for monitoring the geographical extent of nuclear contamination. (Author/SA)

  18. Photometric Studies of GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Edwin; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the SMARTS (Small and Medium Aperture Research Telescope System) 0.9-m at CTIO for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? In this paper we report on the photometric results. For a sample of 50 objects, more than 90 calibrated sequences of R-B-V-I-R magnitudes have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus

  19. Segregation dynamics in debris flows

    NASA Astrophysics Data System (ADS)

    Hill, K. M.; Fei, M.

    2014-12-01

    Debris flows are massive flows consisting of mixtures of particles of different sizes and interstitial fluids such as water and mud. In sheared mixtures of different-sized (same density) particles, it is well known that larger particles tend to go up (toward the free surface), and the smaller particles, down, commonly referred to as the "Brazil-nut problem" or "kinetic sieving". When kinetic sieving fluxes are combined with advection in flows, they can give rise to a spectacular range of segregation patterns. These segregation / advection dynamics are recognized as playing a role in the coarsening of a debris flow front (its "snout") and the coarsening of the self-formed channel sides or levees. Since particle size distribution influences the flow dynamics including entrainment of bed materials, modeling segregation dynamics in debris flows is important for modeling the debris flows themselves. In sparser systems, the Brazil-nut segregation is well-modeled using kinetic theory applied to dissipative systems, where an underlying assumption involves random, uncorrelated collisions. In denser systems, where kinetic theory breaks down we have recently developed a new mixture model that demonstrates the segregation fluxes are driven by two effects associated with the kinetic stress or granular temperature (the kinetic energy associated with velocity fluctuations): (1) the difference between the partitioning of kinetic and contact stresses among the species in the mixture and (2) a kinetic stress gradient. Both model frameworks involve the temperature gradient as a driving force for segregation, but kinetic theory sends larger particles toward lower temperatures, and our mixture model sends larger particles away from lower temperatures. Which framework works under what conditions appears to depend on correlations in the flow such as those manifested in clusters and force chains. We discuss the application of each theoretical framework to representing segregation dynamics

  20. SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH ...

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

    SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN vSHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN SHARP OBLIQUE PERSPECTIVE OF DECK AND APPROACH SPANS ALONG WITH PRINCIPLE CANTILEVER SPAN - Snake River Bridge at Lyons' Ferry, State Route 261 spanning Snake River, Starbuck, Columbia County, WA

  1. Investigation of Gear and Bearing Fatigue Damage Using Debris Particle Distributions

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Lewicki, David G.; Decker, Harry J.

    2004-01-01

    A diagnostic tool was developed for detecting fatigue damage to spur gears, spiral bevel gears, and rolling element bearings. This diagnostic tool was developed and evaluated experimentally by collecting oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig, Spiral Bevel Gear Test Facility, and the 500hp Helicopter Transmission Test Stand. During each test, data from an online, in-line, inductance type oil debris sensor was monitored and recorded for the occurrence of pitting damage. Results indicate oil debris alone cannot discriminate between bearing and gear fatigue damage.

  2. Floating Marine Debris in waters of the Mexican Central Pacific.

    PubMed

    Díaz-Torres, Evelyn R; Ortega-Ortiz, Christian D; Silva-Iñiguez, Lidia; Nene-Preciado, Alejandro; Orozco, Ernesto Torres

    2017-02-15

    The presence of marine debris has been reported recently in several oceans basins; there is very little information available for Mexican Pacific coasts, however. This research examined the composition, possible sources, distribution, and density of Floating Marine Debris (FMD) during nine research surveys conducted during 2010-2012 in the Mexican Central Pacific (MCP). Of 1820 floating objects recorded, 80% were plastic items. Sources of FMD were determined using key objects, which indicated that the most were related to the presence of the industrial harbor and of a growing fishing industry in the study area. Densities were relatively high, ranging from 40 to 2440objects/km(2); the highest densities were recorded in autumn. FMD were distributed near coastal regions, mainly in Jalisco, influenced by river outflow and surface currents. Our results seem to follow worldwide trends and highlight the need for further studies on potential ecological impacts within coastal waters of the MCP. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Detecting debris flows using ground vibrations

    USGS Publications Warehouse

    LaHusen, Richard G.

    1998-01-01

    Debris flows are rapidly flowing mixtures of rock debris, mud, and water that originate on steep slopes. During and following volcanic eruptions, debris flows are among the most destructive and persistent hazards. Debris flows threaten lives and property not only on volcanoes but far downstream in valleys that drain volcanoes where they arrive suddenly and inundate entire valley bottoms. Debris flows can destroy vegetation and structures in their path, including bridges and buildings. Their deposits can cover roads and railways, smother crops, and fill stream channels, thereby reducing their flood-carrying capacity and navigability.

  4. Orbital Debris Research in the United States

    NASA Technical Reports Server (NTRS)

    Stansbery, Gene

    2009-01-01

    The presentation includes information about growth of the satellite population, the U.S. Space Surveillance Network, tracking and catalog maintenance, Haystack and HAX radar observation, Goldstone radar, the Michigan Orbital Debris Survey Telescope (MODEST), spacecraft surface examinations and sample of space shuttle impacts. GEO/LEO observations from Kwajalein Atoll, NASA s Orbital Debris Engineering Model (ORDEM2008), a LEO-to-GEO Environment Debris Model (LEGEND), Debris Assessment Software (DAS) 2.0, the NASA/JSC BUMPER-II meteoroid/debris threat assessment code, satellite reentry risk assessment, optical size and shape determination, work on more complicated fragments, and spectral studies.

  5. An optimal trajectory design for debris deorbiting

    NASA Astrophysics Data System (ADS)

    Ouyang, Gaoxiang; Dong, Xin; Li, Xin; Zhang, Yang

    2016-01-01

    The problem of deorbiting debris is studied in this paper. As a feasible measure, a disposable satellite would be launched, attach to debris, and deorbit the space debris using a technology named electrodynamic tether (EDT). In order to deorbit multiple debris as many as possible, a suboptimal but feasible and efficient trajectory set has been designed to allow a deorbiter satellite tour the LEO small bodies per one mission. Finally a simulation given by this paper showed that a 600 kg satellite is capable of deorbiting 6 debris objects in about 230 days.

  6. The photometric detection of known sun occluding orbital debris

    NASA Astrophysics Data System (ADS)

    Poller, Brian J.

    2009-06-01

    In this research, discrete, digital, Sun transit images are used for the photometric detection of the shadows of Sun occluding satellites. A theoretical pixel occlusion ratio is developed for use in the detection and the occluding area determination of satellites and orbital debris, traveling over known, or predicted, spatial temporal paths during transit. To verify the occluding area determination of a large satellite, a recorded transit of the International Space Station is analyzed. Also an experimental system, funded by a Beverly Sears Grant and a Sigma-Xi Grant-In-Aid of Research, consisting of a Meade ETX-90 telescope, and a Lumenera LU-075 camera is constructed to detect satellites and orbital debris in solar transits. The photometrically measured total occluding area of the Terra EOS-AM1 satellite, recorded in two separate transits, is shown to be consistent with the predicted occluding area of the satellite shadow. Further investigated is the theoretical resolution limit of this detection, as the occluding shadow becomes much smaller than a pixel area. The central limit theorem is used to approximate the maximum detection statistic, which can be achieved when integrating a matched spatial temporal path, containing the moving shadow. This detection statistic is predicted to be a function of the pixel occlusion ratio, the design parameters of the spatial temporal path, and the approximated Poisson variance of the photon count in each pixel. When the measured detection statistics of the two recorded transits are compared with the prediction model, the measurements agree with half the predicted value. This experimental error is largely attributed to filter mismatch in the spatial temporal path, and a spatial temporal variance in the recorded Sun transit images, which is larger than predicted by theory. These experimental verifications of the proposed theory are used to extrapolate the general limitations and capabilities of a system designed to detect Sun

  7. Recent increase in debris flow activity in the Tatras Mountains: results of high-mountain environmental changes?

    NASA Astrophysics Data System (ADS)

    Šilhán, K.

    2016-12-01

    Debris flows are very frequent geomorphic agents that form the relief of the High Tatras Mountains. The knowledge of their history is based on lichenometric dating, historical orthophotos and incomplete archival records. Nevertheless, complete chronologies of debris flows at an annual resolution for the Tatras Mountains have not yet been reconstructed. Accordingly, dendrogeomorphic research in the southern region of the mountains (the Great Cold Valley and Small Cold Valley) was undertaken to reconstruct regional year-to-year chronologies of debris flows, which would present unique perspectives on the debris flow activity. A total of 474 scars on the stems and branches of 414 P. mugo were dated with seasonal precision (the best tool for distinguishing debris flow scars from snow avalanche scars) in 12 debris flow tracks. 22 debris flows over the last circa 30 years (the valid chronological range) in six event years were reconstructed. A significant increase in debris flow activity (verified using historical orthophotos) has occurred since AD 2007 (21 of 22 events occurred during the last decade). Two basic spatial patterns of debris flow activity were identified: regional events with at least five debris flows in one or both valleys and local events with a maximum of two debris flows per year. Based on reports by several authors, increases in extreme precipitation events during the last decade have been observed, but debris flows have not occurred even during the most extreme precipitation events in the study area. Preparatory factors must play an important role at this stage. A significant increase in summer and autumn temperatures at the turn of the 21st century has been reported in the High Tatras Mountains. This could accelerate (dis)continuous permafrost thawing in the source zones, increase the amount of material for the next transport and influence the increase in debris flow activity.

  8. Orbiting space debris: Dangers, measurement and mitigation

    NASA Astrophysics Data System (ADS)

    McNutt, Ross T.

    1992-06-01

    Space debris is a growing environmental problem. Accumulation of objects in earth orbit threatens space systems through the possibility of collisions and runaway debris multiplication. The amount of debris in orbit is uncertain due to the lack of information on the population of debris between 1 and 10 centimeters diameter. Collisions with debris even smaller than 1 cm can be catastrophic due to the high orbital velocities involved. Research efforts are under way at NASA, United States Space Command and the Air Force Phillips Laboratory to detect and catalog the debris population in near-earth space. Current international and national laws are inadequate to control the proliferation of space debris. Space debris is a serious problem with large economic, military, technical and diplomatic components. Actions need to be taken now to: determine the full extent of the orbital debris problem; accurately predict the future evolution of the debris population; decide the extent of the debris mitigation procedures required; implement these policies on a global basis via an international treaty. Action must be initiated now, before the loss of critical space systems such as the space shuttle or the space station.

  9. Orbiting space debris: Dangers, measurement, and mitigation

    NASA Astrophysics Data System (ADS)

    McNutt, Ross T.

    1992-01-01

    Space debris is a growing environmental problem. Accumulation of objects in Earth orbit threatens space systems through the possibility of collisions and runaway debris multiplication. The amount of debris in orbit is uncertain due to the lack of information on the population of debris between 1 and 10 centimeters diameter. Collisions with debris even smaller than 1 cm can be catastrophic due to the high orbital velocities involved. Research efforts are under way at NASA, Unites States Space Command and the Air Force Phillips Laboratory to detect and catalog the debris population in near-Earth space. Current international and national laws are inadequate to control the proliferation of space debris. Space debris is a serious problem with large economic, military, technical, and diplomatic components. Actions need to be taken now for the following reasons: determine the full extent of the orbital debris problem; accurately predict the future evolution of the debris population; decide the extent of the debris mitigation procedures required; implement these policies on a global basis via an international treaty. Action must be initiated now, before the the loss of critical space systems such as the Space Shuttle or the Space Station.

  10. Metric half-span model support system

    NASA Technical Reports Server (NTRS)

    Jackson, C. M., Jr.; Dollyhigh, S. M.; Shaw, D. S. (Inventor)

    1982-01-01

    A model support system used to support a model in a wind tunnel test section is described. The model comprises a metric, or measured, half-span supported by a nonmetric, or nonmeasured half-span which is connected to a sting support. Moments and forces acting on the metric half-span are measured without interference from the support system during a wind tunnel test.

  11. The fast debris evolution model

    NASA Astrophysics Data System (ADS)

    Lewis, H. G.; Swinerd, G. G.; Newland, R. J.; Saunders, A.

    2009-09-01

    The 'particles-in-a-box' (PIB) model introduced by Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] removed the need for computer-intensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FADE), employs a first-order differential equation to describe the rate at which new objects ⩾10 cm are added and removed from the environment. Whilst Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FADE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FADE model has been implemented as a client-side, web-based service using JavaScript embedded within a HTML document. Due to the simple nature of the algorithm, FADE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ⩾10 cm LEO debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model

  12. Space Tourism: Orbital Debris Considerations

    NASA Astrophysics Data System (ADS)

    Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

    2002-01-01

    Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a

  13. Formation of lobate debris aprons on Mars: Assessment of regional ice sheet collapse and debris-cover armoring

    NASA Astrophysics Data System (ADS)

    Fastook, James L.; Head, James W.; Marchant, David R.

    2014-01-01

    ice sheet and exposure of bedrock cliffs. This scenario helps resolve many of the unusual characteristics of lobate debris aprons (LDA) and lineated valley fill (LVF). For example, the distribution of LVF is very consistent with extensive flow of glacial ice from plateau icefields, and the acquisition of a debris cover in the waning stages of retreat of the regional cover as the bedrock scarps are exposed. The typical concentric development of LDA around massifs is much more consistent with ice sheet retreat than insolation-related local accumulation and flow. We thus conclude that the retreating ice-sheet model is robust and should be investigated and tested in more detail. In addition, these results clearly show that the lobate debris aprons in the vicinity of the Dichotomy Boundary could not have attained temperatures near or above the ice melting point and retained their current shape, a finding that supports subzero temperatures for the last several hundred million years, the age of the LDA surfaces. A further implication is that the LDA ice has been preserved for at least several hundred million years, and could potentially contain the record of the climate of Mars, preserved since that time below a sublimation lag deposit.

  14. Space Debris Alert System for Aviation

    NASA Astrophysics Data System (ADS)

    Sgobba, Tommaso

    2013-09-01

    - entry Breakup Recorder (REBR) concept developed by The Aerospace Corporation, often called the black box of spacecraft, and of the Shuttle Hazard Area to Aircraft Calculator (SHAAC). Unlike the REBR, whichdownloads data via satellite link for later analysis, the R-DBAS is intended as a direct communication tool with the end user. As a spacecraft carrying R-DBAS re- enters into the atmosphere, it relays a message with the coordinates of the falling debris footprint area to anyone with a receiver and a display like laptop or iPad, warning them of the hazard.Much like the REBR, the R-DBAS is designed to release from its host vehicle when it experiences significant heat which melts the attachment point and closes the power circuit. Once activated, the R-DBAS determines its own location and computes the final coordinates of the preloaded debris footprint which is then broadcasted to anyone holding a receiver in the proximity of the hazard area.The R-DBAS is intended to provide precise information directly to the cockpit. An airplane would have about 5- 7 minutes to get out of the way. Being the hazard area 1,000-2000 km long but very narrow, 30 -70 km, an escape manoeuvre from the risky area can be readily performed or go on holding before crossing the hazard area.By equipping aircraft and other vulnerable systems with a simple receivers that can be attached to a common laptop, escape manoeuvres can be performed as in front of bad weather or shelter can be taken by people on ground.

  15. Comparison of space debris estimates

    SciTech Connect

    Canavan, G.H.; Judd, O.P.; Naka, R.F.

    1996-10-01

    Debris is thought to be a hazard to space systems through impact and cascading. The current environment is assessed as not threatening to defense systems. Projected reductions in launch rates to LEO should delay concerns for centuries. There is agreement between AFSPC and NASA analyses on catalogs and collision rates, but not on fragmentation rates. Experiments in the laboratory, field, and space are consistent with AFSPC estimates of the number of fragments per collision. A more careful treatment of growth rates greatly reduces long-term stability issues. Space debris has not been shown to be an issue in coming centuries; thus, it does not appear necessary for the Air Force to take additional steps to mitigate it.

  16. Debris flow study in Malaysia

    NASA Astrophysics Data System (ADS)

    Bahrin Jaafar, Kamal

    2016-04-01

    The phenomenon of debris flow occurs in Malaysia occasionally. The topography of Peningsular Malysia is characterized by the central mountain ranges running from south to north. Several parts of hilly areas with steep slopes, combined with high saturation of soil strata that deliberately increase the pore water pressure underneath the hill slope. As a tropical country Malaysia has very high intensity rainfall which is triggered the landslide. In the study area where the debris flow are bound to occur, there are a few factors that contribute to this phenomenon such as high rainfall intensity, very steep slope which an inclination more than 35 degree and sandy clay soil type which is easily change to liquidity soil. This paper will discuss the study of rainfall, mechanism, modeling and design of mitigation measure to avoid repeated failure in future in same area.

  17. Debris Disks and Hidden Planets

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc

    2008-01-01

    When a planet orbits inside a debris disk like the disk around Vega or Beta Pictoris, the planet may be invisible, but the patterns it creates in the disk may give it away. Observing and decoding these patterns may be the only way we can detect exo-Neptunes orbiting more than 20 AU from their stars, and the only way we can spot planets in systems undergoing the late stages of planet formation. Fortunately, every few months, a new image of a debris disk appears with curious structures begging for explanation. I'll describe some new ideas in the theory of these planet-disk interactions and provide a buyers guide to the latest models (and the planets they predict).

  18. Workers Search for Columbia's Debris

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Members of a US Forest Service search team walk a grid during a Columbia recovery search near the Hemphill, Texas site. The group is accompanied by a space program worker able to identify potential hazards of Shuttle parts. Workers from every NASA Center and numerous federal, state, and local agencies searched for Columbia's debris in the recovery effort. For more information on STS-107, please see GRIN Columbia General Explanation

  19. Net Catches Debris From Explosion

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B.; Schneider, William C.

    1992-01-01

    Device restrains fragments and absorbs their kinetic energy. Net of stitched webbing folds compactly over honeycomb plug. Attaches to frame mounted on wall around rectangular area to be cut out by explosion. Honeycomb panel absorbs debris from explosion and crumples into net. Dissipates energy by ripping about 9 in. of stitched net. Developed for emergency escape system in Space Shuttle, adaptable to restraint belts for vehicles; subjecting passengers to more gradual deceleration and less shock.

  20. Comparison of debris flux models

    NASA Astrophysics Data System (ADS)

    Sdunnus, H.; Beltrami, P.; Klinkrad, H.; Matney, M.; Nazarenko, A.; Wegener, P.

    The availability of models to estimate the impact risk from the man-made space debris and the natural meteoroid environment is essential for both, manned and unmanned satellite missions. Various independent tools based on different approaches have been developed in the past years. Due to an increased knowledge of the debris environment and its sources e.g. from improved measurement capabilities, these models could be updated regularly, providing more detailed and more reliable simulations. This paper addresses an in-depth, quantitative comparison of widely distributed debris flux models which were recently updated, namely ESA's MASTER 2001 model, NASA's ORDEM 2000 and the Russian SDPA 2000 model. The comparison was performed in the frame of the work of the 20t h Interagency Debris Coordination (IADC) meeting held in Surrey, UK. ORDEM 2000ORDEM 2000 uses careful empirical estimates of the orbit populations based onthree primary data sources - the US Space Command Catalog, the H ystackaRadar, and the Long Duration Exposure Facility spacecraft returned surfaces.Further data (e.g. HAX and Goldstone radars, impacts on Shuttle windows andradiators, and others) were used to adjust these populations for regions in time,size, and space not covered by the primary data sets. Some interpolation andextrapolation to regions with no data (such as projections into the future) wasprovided by the EVOLVE model. MASTER 2001The ESA MASTER model offers a full three dimensional description of theterrestrial debris distribution reaching from LEO up to the GEO region. Fluxresults relative to an orbiting target or to an inertial volume can be resolved intosource terms, impactor characteristics and orbit, as well as impact velocity anddirection. All relevant debris source terms are considered by the MASTERmodel. For each simulated source, a corresponding debris generation model interms of mass/diameter distribution, additional velocities, and directionalspreading has been developed. A

  1. BINARIES AMONG DEBRIS DISK STARS

    SciTech Connect

    Rodriguez, David R.; Zuckerman, B.

    2012-02-01

    We have gathered a sample of 112 main-sequence stars with known debris disks. We collected published information and performed adaptive optics observations at Lick Observatory to determine if these debris disks are associated with binary or multiple stars. We discovered a previously unknown M-star companion to HD 1051 at a projected separation of 628 AU. We found that 25% {+-} 4% of our debris disk systems are binary or triple star systems, substantially less than the expected {approx}50%. The period distribution for these suggests a relative lack of systems with 1-100 AU separations. Only a few systems have blackbody disk radii comparable to the binary/triple separation. Together, these two characteristics suggest that binaries with intermediate separations of 1-100 AU readily clear out their disks. We find that the fractional disk luminosity, as a proxy for disk mass, is generally lower for multiple systems than for single stars at any given age. Hence, for a binary to possess a disk (or form planets) it must either be a very widely separated binary with disk particles orbiting a single star or it must be a small separation binary with a circumbinary disk.

  2. Orbital Debris Observations with WFCAM

    NASA Astrophysics Data System (ADS)

    Kendrick, R.; Mann, B.; Read, M.; Kerr, T.; Irwin, M.; Cross, N.; Bold, M.,; Varricatt, W.; Madsen, G.

    2014-09-01

    The United Kingdom Infrared Telescope has been operating for 35 years on the summit of Mauna Kea as a premier Infrared astronomical facility. In its 35th year the telescope has been turned over to a new operating group consisting of University of Arizona, University of Hawaii and the LM Advanced Technology Center. UKIRT will continue its astronomical mission with a portion of observing time dedicated to orbital debris and Near Earth Object detection and characterization. During the past 10 years the UKIRT Wide Field CAMera (WFCAM) has been performing large area astronomical surveys in the J, H and K bands. The data for these surveys have been reduced by the Cambridge Astronomical Survey Unit in Cambridge, England and archived by the Wide Field Astronomy Unit in Edinburgh, Scotland. During January and February of 2014 the Wide Field CAMera (WFCAM) was used to scan through the geostationary satellite belt detecting operational satellites as well as nearby debris. Accurate photometric and astrometric parameters have been developed by CASU for each of the detections and all data has been archived by WFAU. This paper will present the January and February results of the orbital debris surveys with WFCAM.

  3. Lightcurves of Extreme Debris Disks

    NASA Astrophysics Data System (ADS)

    Rieke, George; Meng, Huan; Su, Kate

    2012-12-01

    We have recently discovered that some planetary debris disks with extreme fractional luminosities are variable on the timescale of a few years. This behavior opens a new possibility to understand planet building. Two of the known variable disks are around solar-like stars in the age range of 30 to 100+ Myr, which is the expected era of the final stages of terrestrial planet building. Such variability can be attributed to violent collisions (up to ones on the scale of the Moon-forming event between the proto-Earth and another proto-planet). The collisional cascades that are the aftermaths of these events can produce large clouds of tiny dust grains, possibly even condensed from silica vapor. A Spitzer pilot program has obtained the lightcurve of such a debris disk and caught two minor outbursts. Here we propose to continue the lightcurve monitoring with higher sampling rates and to expand it to more disks. The proposed time domain observations are a new dimension of debris disk studies that can bring unique insight to their evolution, providing important constraints on the collisional and dynamical models of terrestrial planet formation.

  4. Debris-Flow Deposition, Valley Storage, and Fluvial Evacuation in Headwater Valleys

    NASA Astrophysics Data System (ADS)

    Lancaster, S. T.; Casebeer, N. E.

    2006-12-01

    Sediment from landscape disturbance often winds up in temporary storage, to be evacuated over longer time spans. In steeplands, there are few constraints on the rate at which sediment stored in valleys is released. We hypothesize that sediment in reaches characterized by debris-flow deposition and evacuation has a distribution of residence times that is distinguishable from those of sediment that is primarily released by fluvial processes. We use field surveys and extensive radiocarbon dating to assess the distribution of deposit ages in two mainstem reaches of a 2.23-km2 watershed in the Oregon Coast Range. In the downstream reach, fluvial deposits are impounded by encroaching debris fans, debris-flow, fine fluvial, and coarse fluvial deposits comprise roughly equal parts of valley storage, and deposits must be evacuated by fluvial erosion. Evacuation times are exponentially distributed with a sample mean of 1.22×103 14C yrs, a distribution indicating uniform probability of evacuation from storage. In the upstream reach, valley-spanning debris jams impound debris-flow deposits comprising >95% of valley storage, which is routinely scoured by debris flows. Evacuation times >100 14C yrs have a power law distribution with a sample mean of 4.43×102 14C yrs, a distribution indicating preferential evacuation of younger deposits and retention of older deposits. In both reaches most sediment is evacuated within short times (<500 14C yrs), but significant volumes remain for millennia. Less than half of basin-wide denudation passes through these "reservoirs," but the latter are still significant buffers between hillslope disturbance and downstream aquatic habitat.

  5. In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

    USGS Publications Warehouse

    Kean, J.W.; Staley, D.M.; Cannon, S.H.

    2011-01-01

    Debris flows often occur in burned steeplands of southern California, sometimes causing property damage and loss of life. In an effort to better understand the hydrologic controls on post-fire debris-flow initiation, timing and magnitude, we measured the flow stage, rainfall, channel bed pore fluid pressure and hillslope soil-moisture accompanying 24 debris flows recorded in five different watersheds burned in the 2009 Station and Jesusita Fires (San Gabriel and Santa Ynez Mountains). The measurements show substantial differences in debris-flow dynamics between sites and between sequential events at the same site. Despite these differences, the timing and magnitude of all events were consistently associated with local peaks in short duration (< = 30 min) rainfall intensity. Overall, debris-flow stage was best cross-correlated with time series of 5-min rainfall intensity, and lagged the rainfall by an average of just 5 min. An index of debris-flow volume was also best correlated with short-duration rainfall intensity, but found to be poorly correlated with storm cumulative rainfall and hillslope soil water content. Post-event observations of erosion and slope stability modeling suggest that the debris flows initiated primarily by processes related to surface water runoff, rather than shallow landslides. By identifying the storm characteristics most closely associated with post-fire debris flows, these measurements provide valuable guidance for warning operations and important constraints for developing and testing models of post-fire debris flows. copyright. 2011 by the American Geophysical Union.

  6. In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

    NASA Astrophysics Data System (ADS)

    Kean, Jason W.; Staley, Dennis M.; Cannon, Susan H.

    2011-12-01

    Debris flows often occur in burned steeplands of southern California, sometimes causing property damage and loss of life. In an effort to better understand the hydrologic controls on post-fire debris-flow initiation, timing and magnitude, we measured the flow stage, rainfall, channel bed pore fluid pressure and hillslope soil-moisture accompanying 24 debris flows recorded in five different watersheds burned in the 2009 Station and Jesusita Fires (San Gabriel and Santa Ynez Mountains). The measurements show substantial differences in debris-flow dynamics between sites and between sequential events at the same site. Despite these differences, the timing and magnitude of all events were consistently associated with local peaks in short duration (< = 30 min) rainfall intensity. Overall, debris-flow stage was best cross-correlated with time series of 5-min rainfall intensity, and lagged the rainfall by an average of just 5 min. An index of debris-flow volume was also best correlated with short-duration rainfall intensity, but found to be poorly correlated with storm cumulative rainfall and hillslope soil water content. Post-event observations of erosion and slope stability modeling suggest that the debris flows initiated primarily by processes related to surface water runoff, rather than shallow landslides. By identifying the storm characteristics most closely associated with post-fire debris flows, these measurements provide valuable guidance for warning operations and important constraints for developing and testing models of post-fire debris flows.

  7. Space Shuttle Solid Rocket Booster Debris Assessment

    NASA Technical Reports Server (NTRS)

    Kendall, Kristin; Kanner, Howard; Yu, Weiping

    2006-01-01

    The Space Shuttle Columbia Accident revealed a fundamental problem of the Space Shuttle Program regarding debris. Prior to the tragedy, the Space Shuttle requirement stated that no debris should be liberated that would jeopardize the flight crew and/or mission success. When the accident investigation determined that a large piece of foam debris was the primary cause of the loss of the shuttle and crew, it became apparent that the risk and scope of - damage that could be caused by certain types of debris, especially - ice and foam, were not fully understood. There was no clear understanding of the materials that could become debris, the path the debris might take during flight, the structures the debris might impact or the damage the impact might cause. In addition to supporting the primary NASA and USA goal of returning the Space Shuttle to flight by understanding the SRB debris environment and capability to withstand that environment, the SRB debris assessment project was divided into four primary tasks that were required to be completed to support the RTF goal. These tasks were (1) debris environment definition, (2) impact testing, (3) model correlation and (4) hardware evaluation. Additionally, the project aligned with USA's corporate goals of safety, customer satisfaction, professional development and fiscal accountability.

  8. Behavior of tethered debris with flexible appendages

    NASA Astrophysics Data System (ADS)

    Aslanov, Vladimir S.; Yudintsev, Vadim V.

    2014-11-01

    Active exploration of the space leads to growth of a near-Earth space pollution. The frequency of the registered collisions of space debris with functional satellites highly increased during last 10 years. As a rule a large space debris can be observed from the Earth and catalogued, then it is possible to avoid collision with the active spacecraft. However every large debris is a potential source of a numerous small debris particles. To reduce debris population in the near Earth space the large debris should be removed from working orbits. The active debris removal technique is considered that intend to use a tethered orbital transfer vehicle, or a space tug attached by a tether to the space debris. This paper focuses on the dynamics of the space debris with flexible appendages. Mathematical model of the system is derived using the Lagrange formalism. Several numerical examples are presented to illustrate the mutual influence of the oscillations of flexible appendages and the oscillations of a tether. It is shown that flexible appendages can have a significant influence on the attitude motion of the space debris and the safety of the transportation process.

  9. LAD-C: A large area debris collector on the ISS

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Giovane, F. J.; Corsaro, R. D.; Burchell, M. J.; Drolshagen, G.; Kawai, H.; Stansbery, E. G.; Tabata, M.; Westphal, A. J.; Yano, H.

    2006-01-01

    The Large Area Debris Collector (LAD-C) is a 10 sq m aerogel and acoustic sensor system under development by the U.S. Naval Research Laboratory (NRL) with main collaboration from the NASA Orbital Debris Program Office at Johnson Space Center, JAXA Institute of Space and Astronautical Science (ISAS), Chiba University (Japan), ESA Space Debris Office, University of California at Berkeley, and University of Kent at Canterbury (UK). The U.S. Department of Defense (DoD) Space Test Program (STP) has assumed the responsibility for having the system manifested and deployed on the International Space Station (ISS), and then having it retrieved and returned to Earth after one to two years. LAD-C will attempt to utilize the ISS as a scientific platform to characterize the near-Earth meteoroid and orbital debris environment in the size regime where little data exist. In addition to meteoroid and orbital debris sample return, the acoustic sensors will record impact time, location, signal strength, and acoustic waveform data of the largest collected samples. A good time-dependent meteoroid and orbital debris flux estimate can be derived. Analysis of the data will also enable potential source identification of some of the collected samples. This dynamical link can be combined with laboratory composition analysis of impact residuals extracted from aerogel to further our understanding of orbital debris population, and the sources of meteoroids, asteroids and comets.

  10. Marine debris ingestion in loggerhead sea turtles, Caretta caretta, from the Western Mediterranean.

    PubMed

    Tomás, J; Guitart, R; Mateo, R; Raga, J A

    2002-03-01

    Marine debris represents an important threat for sea turtles, but information on this topic is scarce in some areas, such as the Mediterranean sea. This paper quantifies marine debris ingestion in 54 juvenile loggerhead sea turtles (Caretta caretta) illegally captured by fishermen in Spanish Mediterranean waters. Curved carapace length was measured, necropsies were performed and debris abundance and type was recorded. Different types of debris appeared in the gastrointestinal tract of 43 turtles (79.6%), being plastics the most frequent (75.9%). Tar, paper, Styrofoam, wood, reed, feathers, hooks, lines, and net fragments were also present. A regression analysis showed that the volume of debris increased proportionally to the size of the turtles. The high variety of debris found and the large differences in ingestion among turtles indicated low feeding discrimination of this species that makes it specially prone to debris ingestion. Our data suggest that more severe control of litter spills and greater promotion of environmental educational programmes are needed in the Western Mediterranean.

  11. Assessment of the debris-flow susceptibility in tropical mountains using clast distribution patterns

    NASA Astrophysics Data System (ADS)

    de Carvalho Faria Lima Lopes, Laís; de Almeida Prado Bacellar, Luís; Amorim Castro, Paulo de Tarso

    2016-12-01

    Channel morphometric parameters and clast distribution patterns in selected basins of the Ferriferous Quadrangle tropical mountains, Brazil, were analyzed in order to assess susceptibility to debris flows. Median bed surface clast size (D50) in the main stream channel of these basins shows a coarsening downstream trend with drainage areas of up to 6 km2, which is attributed to debris flow dominated-channels by some authors. The composition and roundness of the bed load, clast sand, and the presence of allochthonous large boulders throughout the channels also suggest the occurrence of past debris flow in the region. Luminescence Optically Stimulated (LOE) dating points out that debris flow could have occurred as a consequence of climate changes in the Late Pleistocene and Holocene and it can now be triggered by deforestation or extreme rainfall events. There has not been any record of past debris flow in the study area, or in other mountainous regions of Brazil where debris flows have recently occurred. Thus, the adopted approach can be useful to assess debris flow susceptibility in this and other similar areas.

  12. Debris Flow Distributed Propagation Model

    NASA Astrophysics Data System (ADS)

    Gregoretti, C.

    The debris flow distributed propagation model is a DEM-based model. The fan is dis- cretized by square cells and each cell is assigned an altitude on the sea level. The cells of the catchment are distinguished in two categories: the source cells and the stripe cells. The source cells receive the input hydograph: the cells close to the torrent which are flooded by the debris flow overflowing the torrent embankment are source cells. The stripes cells are the cells flooded by debris flow coming from the surrounding cells. At the first time step only the source cells are flooded by debris flow coming from the torrent. At the second time step a certain number of cells are flooded by de- bris flow coming from the source cells. These cells constitute a stripe of cells and are assigned order two. At the third time step another group of cells are flooded by the debris flow coming from the cells whose order is two. These cells constitute another stripe and are assigned order three. The cell order of a stripe is the time step number corresponding to the transition from dry to flooded state. The mass transfer or mo- mentum exchange between cells is governed by two different mechanisms. The mass transfer is allowed only by a positive or equal to zero flow level difference between the drained cell and the receiving cell. The mass transfer is limited by a not negative final flow level difference between the drained cell and the receiving cells. This limitation excludes the case of possible oscillations in the mass transfer. Another limitation is that the mass drained by a cell should be less than the available mass in that cell. This last condition provides the respect of mass conservation. The first mechanism of mass transfer is the gravity. The mass in a cell is transferred to the neighbouring cells with lower altitude and flow level according to an uniform flow law: The second mecha- nism of mass transfer is the broad crested weir. The mass in a cell is transferred to the

  13. Node degree distribution in spanning trees

    NASA Astrophysics Data System (ADS)

    Pozrikidis, C.

    2016-03-01

    A method is presented for computing the number of spanning trees involving one link or a specified group of links, and excluding another link or a specified group of links, in a network described by a simple graph in terms of derivatives of the spanning-tree generating function defined with respect to the eigenvalues of the Kirchhoff (weighted Laplacian) matrix. The method is applied to deduce the node degree distribution in a complete or randomized set of spanning trees of an arbitrary network. An important feature of the proposed method is that the explicit construction of spanning trees is not required. It is shown that the node degree distribution in the spanning trees of the complete network is described by the binomial distribution. Numerical results are presented for the node degree distribution in square, triangular, and honeycomb lattices.

  14. Risk assessment reveals high exposure of sea turtles to marine debris in French Mediterranean and metropolitan Atlantic waters

    NASA Astrophysics Data System (ADS)

    Darmon, Gaëlle; Miaud, Claude; Claro, Françoise; Doremus, Ghislain; Galgani, François

    2017-07-01

    Debris impact on marine wildlife has become a major issue of concern. Mainy species have been identified as being threatened by collision, entanglement or ingestion of debris, generally plastics, which constitute the predominant part of the recorded marine debris. Assessing sensitive areas, where exposure to debris are high, is thus crucial, in particular for sea turtles which have been proposed as sentinels of debris levels for the Marine Strategy Framework Directive and for the Unep-MedPol convention. Our objective here was to assess sea turtle exposure to marine debris in the 3 metropolitan French fronts. Using aerial surveys performed in the Channel, the Atlantic and the Mediterranean regions in winter and summer 2011-2012, we evaluated exposure areas and magnitude in terms of spatial overlap, encounter probability and density of surrounding debris at various spatial scales. Major overlapping areas appeared in the Atlantic and Mediterranean fronts, concerning mostly the leatherback and the loggerhead turtles respectively. The probability for individuals to be in contact with debris (around 90% of individuals within a radius of 2 km) and the density of debris surrounding individuals (up to 16 items with a radius of 2 km, 88 items within a radius of 10 km) were very high, whatever the considered spatial scale, especially in the Mediterranean region and during the summer season. The comparison of the observed mean debris density with random distribution suggested that turtles selected debris areas. This may occur if both debris and turtles drift to the same areas due to currents, if turtles meet debris accidentally by selecting high food concentration areas, and/or if turtles actively seek debris out, confounding them with their preys. Various factors such as species-specific foraging strategies or oceanic features which condition the passive diffusion of debris, and sea turtles in part, may explain spatio-temporal variations in sensitive areas. Further research

  15. The influence of selected containment structures on debris dispersal and transport following high pressure melt ejection from the reactor vessel

    SciTech Connect

    Pilch, M.; Tarbell, W.W.; Brockmann, J.E.

    1988-09-01

    High pressure expulsion of molten core debris from the reactor pressure vessel may result in dispersal of the debris from the reactor cavity. In most plants, the cavity exits into the containment such that the debris impinges on structures. Retention of the debris on the structures may affect the further transport of the debris throughout the containment. Two tests were done with scaled structural shapes placed at the exit of 1:10 linear scale models of the Zion cavity. The results show that the debris does not adhere significantly to structures. The lack of retention is attributed to splashing from the surface and reentrainment in the gas flowing over the surface. These processes are shown to be applicable to reactor scale. A third experiment was done to simulate the annular gap between the reactor vessel and cavity wall. Debris collection showed that the fraction of debris exiting through the gap was greater than the gap-to-total flow area ratio. Film records indicate that dispersal was primarily by entrainment of the molten debris in the cavity. 29 refs., 36 figs., 11 tabs.

  16. Debris Flows Within The Greater Caucasus Northern Slope

    NASA Astrophysics Data System (ADS)

    Panova, S.

    Debris flows are recorded everywhere within the Greater Caucasus northern slope. In last decades studies of debris flows appeared to be very important due to an intensive anthropogenic activity in the mountainous areas. Debris flow spatial distribution, as well as their genesis and means of protection are critical, too. The studied terri- tory has significant absolute altitudes, especially in the central and eastern parts. Also large amount of atmospheric precipitation with maximum in a warm period is typical for the region. Modern glaciation with soil-covered moraine deposits of modern and Holocene age is developed in the region. Geological and geomorphological conditions lead to debris flows formation within the entire territory. However, the amount of atmospheric precipitation drastically decreases from west to east and in the eastern part (Dagestan) debris flow is less active than in the central even under the presence of enormous amounts of loose detrital material of different genesis. In the western part debris flows are less developed due to insignificant altitudes and considerable forest coverage and soil-cover. Powerful modern glaciation with vast development of purely moraine and fluvial-glacial deposits results in intensive debris flow activity in the central part of the northern slope (the Terek river basin). In the upper reaches of all the Terek tributaries moraine deposits reach up to several dozen meters. They are widespread at altitudes higher than 2000 m (above the forest boundary) and almost everywhere uncovered by soils. They are a key source of sediments under debris flow formation. Within the Greater Caucasus northern slope there are 1700 debris flow basins with the total area about 7000 km2. Their average area is 4.0 km2 with minimum 0.20 km2 and maximum 173.8 km2. Moreover, there are many riverbeds in the area where form mountain mud floods more than 3000 km long. Debris flows occur between January and October with clear altitudinal zoning

  17. 2. DETAIL VIEW OF ON RIGHT FOREGROUND FIXED SPAN TO ...

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

    2. DETAIL VIEW OF ON RIGHT FOREGROUND FIXED SPAN TO TRANSITIONAL MOVEABLE SPAN TO FLOATING SPAN IN MIDDLEGROUND - Lacey V. Murrow Memorial Floating Bridge, Spanning Lake Washington at I-90, Seattle, King County, WA

  18. 3. View west. North elevation Walpole span in foreground, ...

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

    3. View west. North elevation - Walpole span in foreground, link span; Westminster span in background. - Walpole-Westminster Bridge, Spanning Connecticut River between Walpole, NH & Westminster, VT, Walpole, Cheshire County, NH

  19. Orbital debris characterization with impact flash signatures

    SciTech Connect

    Ang, J.A.

    1991-12-31

    Orbital debris is recognized as a serious and growing threat to man`s utilization and exploration of space. While some information is available on the material composition of orbital debris, most measurements of orbital debris size and velocity distributions do not distinguish material type. The analysis and understanding of impact flash signatures can lead to an in-situ detector system with the ability to determine size and impact velocity distribution for orbital debris segregated by material type. This detector concept is based on an understanding of how material shock properties govern the flash signature arising from the impact of a piece of orbital debris (impactor) against a witness plate (target). Analytical results are presented that identify the most promising witness plate materials with respect to producing impact flash signatures that characterize the orbital debris material. 7 refs.

  20. Orbital debris characterization with impact flash signatures

    SciTech Connect

    Ang, J.A.

    1991-01-01

    Orbital debris is recognized as a serious and growing threat to man's utilization and exploration of space. While some information is available on the material composition of orbital debris, most measurements of orbital debris size and velocity distributions do not distinguish material type. The analysis and understanding of impact flash signatures can lead to an in-situ detector system with the ability to determine size and impact velocity distribution for orbital debris segregated by material type. This detector concept is based on an understanding of how material shock properties govern the flash signature arising from the impact of a piece of orbital debris (impactor) against a witness plate (target). Analytical results are presented that identify the most promising witness plate materials with respect to producing impact flash signatures that characterize the orbital debris material. 7 refs.

  1. Orbital debris: Technical issues and future directions

    NASA Technical Reports Server (NTRS)

    Potter, Andrew (Editor)

    1992-01-01

    An international conference on orbital debris sponsored jointly by the American Institute of Aeronautics and Astronautics, NASA, and the Department of Defense, was held in Baltimore, Maryland, 16-19 Apr. 1990. Thirty-three papers were presented. The papers were grouped into the areas of measurements, modeling, and implications of orbital debris for space flight. New radar and optical measurements of orbital debris were presented that showed the existence of a large population of small debris. Modeling of potential future environments showed that runaway growth of the debris population from random collisions was a real possibility. New techniques for shielding against orbital debris and methods for removal of satellites from orbit were discussed.

  2. Debris impact on Earth-orbiting spacecraft

    NASA Technical Reports Server (NTRS)

    Smith, D. G.

    1985-01-01

    The accumulation of Earth-orbiting space debris leads to important new design considerations. Some 5,000 orbiting objects, many of them explosion fragments, are currently being tracked and future collision of these objects with each other is predicted. These collisions will occur at high velocities. Each collision will be explosive, ejecting thousands, of new orbiting objects, in turn increasing the frequency of future collisions. The debris population may thus become self-regenerative, and the future flux of orbiting debris will exceed that of meteoroids. As a result, a large space structure in Earth-orbit for several years has a significant probability of impact by debris objects. As a design problem, debris impact is significantly different from meteoroid impact. Protection against such large objects may require structural measures. The consideration of debris impact in the design of large, Earth-orbiting spacecraft is recommended.

  3. Evaluating tsunami hazards from debris flows

    USGS Publications Warehouse

    Watts, P.; Walder, J.S.; ,

    2003-01-01

    Debris flows that enter water bodies may have significant kinetic energy, some of which is transferred to water motion or waves that can impact shorelines and structures. The associated hazards depend on the location of the affected area relative to the point at which the debris flow enters the water. Three distinct regions (splash zone, near field, and far field) may be identified. Experiments demonstrate that characteristics of the near field water wave, which is the only coherent wave to emerge from the splash zone, depend primarily on debris flow volume, debris flow submerged time of motion, and water depth at the point where debris flow motion stops. Near field wave characteristics commonly may be used as & proxy source for computational tsunami propagation. This result is used to assess hazards associated with potential debris flows entering a reservoir in the northwestern USA. ?? 2003 Millpress,.

  4. Distribution and assessment of marine debris in the deep Tyrrhenian Sea (NW Mediterranean Sea, Italy).

    PubMed

    Angiolillo, Michela; Lorenzo, Bianca di; Farcomeni, Alessio; Bo, Marzia; Bavestrello, Giorgio; Santangelo, Giovanni; Cau, Angelo; Mastascusa, Vincenza; Cau, Alessandro; Sacco, Flavio; Canese, Simonepietro

    2015-03-15

    Marine debris is a recognized global ecological concern. Little is known about the extent of the problem in the Mediterranean Sea regarding litter distribution and its influence on deep rocky habitats. A quantitative assessment of debris present in the deep seafloor (30-300 m depth) was carried out in 26 areas off the coast of three Italian regions in the Tyrrhenian Sea, using a Remotely Operated Vehicle (ROV). The dominant type of debris (89%) was represented by fishing gears, mainly lines, while plastic objects were recorded only occasionally. Abundant quantities of gears were found on rocky banks in Sicily and Campania (0.09-0.12 debris m(-2)), proving intense fishing activity. Fifty-four percent of the recorded debris directly impacted benthic organisms, primarily gorgonians, followed by black corals and sponges. This work provides a first insight on the impact of marine debris in Mediterranean deep ecosystems and a valuable baseline for future comparisons. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Debris Removal: An Opportunity for Cooperative Research?

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2007-01-01

    Space debris mitigation practices will be insufficient to prevent the continued growth of the Earth satellite population. Removal of orbital debris can improve the reliability of present and future space systems. The challenges of developing an effective, affordable debris removal capability are considerable. The time is right for a new look at space remediation concepts. In concert with or following the current IAA study An international approach to the remediation of the near-Earth space environment will likely be required.

  6. Orbiting Space Debris: Dangers, Measurement and Mitigation

    DTIC Science & Technology

    1992-01-01

    B.5 Raw Video Signal of Debris Streak - Single Frame 281 Figure B.6 50 Shifted and Added Video Frames After 282 Background Subtraction Figure B.7...caused collisions. The leading candidate for a hyper-velocity collision with debris is the Cosmos 1275 fragmentation in 1981 which created 281 ...sensitivity. 280 SA ~ .0 . n I I4 MOM- Figure B.5 Raw Video Signal of Debris Streak - Single Frame 281 Figure B.6 50 Shifted and Added Video Frames After

  7. Best Mitigation Paths To Effectively Reduce Earth's Orbital Debris

    NASA Technical Reports Server (NTRS)

    Wiegman, Bruce M.

    2009-01-01

    This slide presentation reviews some ways to reduce the problem posed by debris in orbit around the Earth. It reviews the orbital debris environment, the near-term needs to minimize the Kessler syndrome, also known as collisional cascading, a survey of active orbital debris mitigation strategies, the best paths to actively remove orbital debris, and technologies that are required for active debris mitigation.

  8. Variations in debris distribution and thickness on Himalayan debris-covered glaciers

    NASA Astrophysics Data System (ADS)

    Gibson, Morgan; Rowan, Ann; Irvine-Fynn, Tristram; Quincey, Duncan; Glasser, Neil

    2016-04-01

    Many Himalayan glaciers are characterised by extensive supraglacial debris coverage; in Nepal 33% of glaciers exhibit a continuous layer of debris covering their ablation areas. The presence of such a debris layer modulates a glacier's response to climatic change. However, the impact of this modulation is poorly constrained due to inadequate quantification of the impact of supraglacial debris on glacier surface energy balance. Few data exist to describe spatial and temporal variations in parameters such as debris thickness, albedo and surface roughness in energy balance calculations. Consequently, improved understanding of how debris affects Himalayan glacier ablation requires the assessment of surface energy balance model sensitivity to spatial and temporal variability in these parameters. Measurements of debris thickness, surface temperature, reflectance and roughness were collected across Khumbu Glacier during the pre- and post-monsoon seasons of 2014 and 2015. The extent of the spatial variation in each of these parameters are currently being incorporated into a point-based glacier surface energy balance model (CMB-RES, Collier et al., 2014, The Cryosphere), applied on a pixel-by-pixel basis to the glacier surface, to ascertain the sensitivity of glacier surface energy balance and ablation values to these debris parameters. A time series of debris thickness maps have been produced for Khumbu Glacier over a 15-year period (2000-2015) using Mihalcea et al.'s (2008, Cold Reg. Sci. Technol.) method, which utilised multi-temporal ASTER thermal imagery and our in situ debris surface temperature and thickness measurements. Change detection between these maps allowed the identification of variations in debris thickness that could be compared to discrete measurements, glacier surface velocity and morphology of the debris-covered area. Debris thickness was found to vary spatially between 0.1 and 4 metres within each debris thickness map, and temporally on the order of 1

  9. Process Knowledge Summary Report for Materials and Fuels Complex Contact-Handled Transuranic Debris Waste

    SciTech Connect

    R. P. Grant; P. J. Crane; S. Butler; M. A. Henry

    2010-02-01

    This Process Knowledge Summary Report summarizes the information collected to satisfy the transportation and waste acceptance requirements for the transfer of transuranic (TRU) waste between the Materials and Fuels Complex (MFC) and the Advanced Mixed Waste Treatment Project (AMWTP). The information collected includes documentation that addresses the requirements for AMWTP and the applicable portion of their Resource Conservation and Recovery Act permits for receipt and treatment of TRU debris waste in AMWTP. This report has been prepared for contact-handled TRU debris waste generated by the Idaho National Laboratory at MFC. The TRU debris waste will be shipped to AMWTP for purposes of supercompaction. This Process Knowledge Summary Report includes information regarding, but not limited to, the generation process, the physical form, radiological characteristics, and chemical contaminants of the TRU debris waste, prohibited items, and packaging configuration. This report, along with the referenced supporting documents, will create a defensible and auditable record for waste originating from MFC.

  10. Debris flows: geologic process and hazard; illustrated by a surge sequence at Jiangjia Ravine, Yunnan, China

    USGS Publications Warehouse

    Scott, Kevin M.; Yuyi, Wang

    2004-01-01

    Debris flows are slurries of sediment and water that are both an important geologic process and a major hazard. They present large risks to those living in mountainous areas, as well as downstream from volcanoes in the case of the flows known as lahars that may travel 100200 kilometers (62-124 miles). The accompanying video records a series of debris flow surges at Jiangjia Ravine, in Yunnan Province in southern China. This rugged and remote site is famous for the annual occurrence of debris flows triggered each summer by monsoonal rains. The video illustrates the unique characteristics of debris flows, how they behave, and why they cause large losses of life and property in China and many other parts of the world. This report is a summary for those wishing more information than is presented in the video, and for the specialist we include dynamical data on the flows and textural data on their deposits.

  11. Primary dispersal of supraglacial debris and debris cover formation on alpine glaciers

    NASA Astrophysics Data System (ADS)

    Kirkbride, M. P.; Deline, P.

    2009-04-01

    Debris-covered glaciers are receiving increased attention due to the modulation of runoff by supraglacial covers, and to the lake outburst flood hazard at many covered glacier termini. Observed increases in debris cover extents cannot presently be explained in terms of glaciological influences. The supply of englacial debris to the supraglacial zone has previously been understood only in terms of local dispersal due to differential ablation between covered and uncovered ice, for example on medial moraines. Here, we introduce the term primary dispersal to describe the process of migration of the outcrops of angled debris septa across melting, thinning ablation zones. Understanding primary debris dispersal is an essential step to understanding how supraglacial debris cover is controlled by glaciological variables, and hence is sensitive to climatically-induced fluctuation. Three measures of a glacier's ability to evacuate supraglacial debris are outlined: (1) a concentration factor describing the focussing of englacial debris into specific supraglacial mass loads; (2) the rate of migration of a septum outcrop relative to the local ice surface; and (3) a downstream velocity differential between a septum outcrop and the ice surface. (1) and (2) are inversely related, while (3) increases downglacier to explain why slow-moving, thinning ice rapidly becomes debris covered. Data from Glacier d'Estelette (Italian Alps) illustrate primary dispersal processes at a site where debris cover is increasing in common with many other shrinking alpine glaciers. We develop a model of the potential for debris cover formation and growth in different glaciological environments. This explains why glaciers whose termini are obstructed often have steep debris septa feeding debris covers which vary slowly in response to mass balance change. In contrast, at glaciers with gently-dipping debris-bearing foliation, the debris cover extent is sensitive to glaciological change. These findings

  12. Debris Selection and Optimal Path Planning for Debris Removal on the SSO: Impulsive-Thrust Option

    NASA Astrophysics Data System (ADS)

    Olympio, J. T.; Frouvelle, N.

    2013-08-01

    The current paper deals with the mission design of a generic active space debris removal spacecraft. Considered debris are all on a sun-synchronous orbit. A perturbed Lambert's problem, modelling the transfer between two debris, is devised to take into account J2 perturbation, and to quickly evaluate mission scenarios. A robust approach, using techniques of global optimisation, is followed to find optimal debris sequence and mission strategy. Manoeuvres optimization is then performed to refine the selected trajectory scenarii.

  13. Debris-cloud collisions: Accretion studies in the space station

    NASA Technical Reports Server (NTRS)

    Schultz, P. H.; Gault, D. E.

    1986-01-01

    The growth of planetesimals in the Solar system reflects the success of collisional aggregation over disruption. Recent experiments performed at the NASA-Ames Vertical Gun Range are discussed using the production of debris cloud impaction to model protoplanetary accretion. The impact experiment assessed the differences between clustered and single body impacts on particulate surfaces. The preliminary results would indicate that collisions between two debris clouds might produce aggregates, thereby increasing particle sizes, whereas a single particle impacting a particle results in disruption and comminution. Such an experiment could provide new insight for early planetary growth processes and for interpreting the record of this stage. The use of the microgravity environment of the Space Station to further the research is discussed.

  14. Space debris measurement program at Phillips Laboratory

    NASA Technical Reports Server (NTRS)

    Dao, Phan D.; Mcnutt, Ross T.

    1992-01-01

    Ground-based optical sensing was identified as a technique for measuring space debris complementary to radar in the critical debris size range of 1 to 10 cm. The Phillips Laboratory is building a staring optical sensor for space debris measurement and considering search and track optical measurement at additional sites. The staring sensor is implemented in collaboration with Wright Laboratory using the 2.5 m telescope at Wright Patterson AFB, Dayton, Ohio. The search and track sensor is designed to detect and track orbital debris in tasked orbits. A progress report and a discussion of sensor performance and search and track strategies will be given.

  15. Space debris mitigation measures in India

    NASA Astrophysics Data System (ADS)

    Adimurthy, V.; Ganeshan, A. S.

    2006-02-01

    The Indian Space Research Organization (ISRO) recognizes the importance of the current space debris scenario, and the impact it has on the effective utilization of space technology for the improvement in the quality of life on the Earth. ISRO is committed to effective management of the threats due to space debris. Towards this commitment ISRO works on different aspects of space debris, including the debris mitigation measures. This paper highlights the activities and achievements in the implementation of the mitigation measures. ISRO successfully designed and developed a propellant venting system for implementation in the existing upper stage of India's Polar Satellite Launch Vehicle (PSLV), which uses Earth-storable liquid propellants. GSLV also employs passivation of the Cryogenic Upper Stage at the end of its useful mission. ISRO's communication satellites in GSO are designed with adequate propellant margins for re-orbiting at the end of their useful life to a higher graveyard orbit. A typical successful operation in connection with INSAT-2C is described. ISRO developed its debris environmental models and software to predict the close approach of any of the debris to the functional satellites. The software are regularly used for the debris risk management of the orbiting spacecraft and launch vehicles. ISRO recognizes the role of international cooperation in the debris mitigation measures and actively contributes to the efforts of the Inter-Agency Space Debris Coordination Committee (IADC) and United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS).

  16. The feeding habit of sea turtles influences their reaction to artificial marine debris

    PubMed Central

    Fukuoka, Takuya; Yamane, Misaki; Kinoshita, Chihiro; Narazaki, Tomoko; Marshall, Greg J.; Abernathy, Kyler J.; Miyazaki, Nobuyuki; Sato, Katsufumi

    2016-01-01

    Ingestion of artificial debris is considered as a significant stress for wildlife including sea turtles. To investigate how turtles react to artificial debris under natural conditions, we deployed animal-borne video cameras on loggerhead and green turtles in addition to feces and gut contents analyses from 2007 to 2015. Frequency of occurrences of artificial debris in feces and gut contents collected from loggerhead turtles were 35.7% (10/28) and 84.6% (11/13), respectively. Artificial debris appeared in all green turtles in feces (25/25) and gut contents (10/10), and green turtles ingested more debris (feces; 15.8 ± 33.4 g, gut; 39.8 ± 51.2 g) than loggerhead turtles (feces; 1.6 ± 3.7 g, gut; 9.7 ± 15.0 g). In the video records (60 and 52.5 hours from 10 loggerhead and 6 green turtles, respectively), turtles encountered 46 artificial debris and ingested 23 of them. The encounter-ingestion ratio of artificial debris in green turtles (61.8%) was significantly higher than that in loggerhead turtles (16.7%). Loggerhead turtles frequently fed on gelatinous prey (78/84), however, green turtles mainly fed marine algae (156/210), and partly consumed gelatinous prey (10/210). Turtles seemed to confuse solo drifting debris with their diet, and omnivorous green turtles were more attracted by artificial debris. PMID:27305858

  17. The feeding habit of sea turtles influences their reaction to artificial marine debris.

    PubMed

    Fukuoka, Takuya; Yamane, Misaki; Kinoshita, Chihiro; Narazaki, Tomoko; Marshall, Greg J; Abernathy, Kyler J; Miyazaki, Nobuyuki; Sato, Katsufumi

    2016-06-16

    Ingestion of artificial debris is considered as a significant stress for wildlife including sea turtles. To investigate how turtles react to artificial debris under natural conditions, we deployed animal-borne video cameras on loggerhead and green turtles in addition to feces and gut contents analyses from 2007 to 2015. Frequency of occurrences of artificial debris in feces and gut contents collected from loggerhead turtles were 35.7% (10/28) and 84.6% (11/13), respectively. Artificial debris appeared in all green turtles in feces (25/25) and gut contents (10/10), and green turtles ingested more debris (feces; 15.8 ± 33.4 g, gut; 39.8 ± 51.2 g) than loggerhead turtles (feces; 1.6 ± 3.7 g, gut; 9.7 ± 15.0 g). In the video records (60 and 52.5 hours from 10 loggerhead and 6 green turtles, respectively), turtles encountered 46 artificial debris and ingested 23 of them. The encounter-ingestion ratio of artificial debris in green turtles (61.8%) was significantly higher than that in loggerhead turtles (16.7%). Loggerhead turtles frequently fed on gelatinous prey (78/84), however, green turtles mainly fed marine algae (156/210), and partly consumed gelatinous prey (10/210). Turtles seemed to confuse solo drifting debris with their diet, and omnivorous green turtles were more attracted by artificial debris.

  18. The feeding habit of sea turtles influences their reaction to artificial marine debris

    NASA Astrophysics Data System (ADS)

    Fukuoka, Takuya; Yamane, Misaki; Kinoshita, Chihiro; Narazaki, Tomoko; Marshall, Greg J.; Abernathy, Kyler J.; Miyazaki, Nobuyuki; Sato, Katsufumi

    2016-06-01

    Ingestion of artificial debris is considered as a significant stress for wildlife including sea turtles. To investigate how turtles react to artificial debris under natural conditions, we deployed animal-borne video cameras on loggerhead and green turtles in addition to feces and gut contents analyses from 2007 to 2015. Frequency of occurrences of artificial debris in feces and gut contents collected from loggerhead turtles were 35.7% (10/28) and 84.6% (11/13), respectively. Artificial debris appeared in all green turtles in feces (25/25) and gut contents (10/10), and green turtles ingested more debris (feces; 15.8 ± 33.4 g, gut; 39.8 ± 51.2 g) than loggerhead turtles (feces; 1.6 ± 3.7 g, gut; 9.7 ± 15.0 g). In the video records (60 and 52.5 hours from 10 loggerhead and 6 green turtles, respectively), turtles encountered 46 artificial debris and ingested 23 of them. The encounter-ingestion ratio of artificial debris in green turtles (61.8%) was significantly higher than that in loggerhead turtles (16.7%). Loggerhead turtles frequently fed on gelatinous prey (78/84), however, green turtles mainly fed marine algae (156/210), and partly consumed gelatinous prey (10/210). Turtles seemed to confuse solo drifting debris with their diet, and omnivorous green turtles were more attracted by artificial debris.

  19. Model simulations of flood and debris flow timing in steep catchments after wildfire

    NASA Astrophysics Data System (ADS)

    Rengers, F. K.; McGuire, L. A.; Kean, J. W.; Staley, D. M.; Hobley, D. E. J.

    2016-08-01

    Debris flows are a typical hazard on steep slopes after wildfire, but unlike debris flows that mobilize from landslides, most postwildfire debris flows are generated from water runoff. The majority of existing debris flow modeling has focused on landslide-triggered debris flows. In this study we explore the potential for using process-based rainfall-runoff models to simulate the timing of water flow and runoff-generated debris flows in recently burned areas. Two different spatially distributed hydrologic models with differing levels of complexity were used: the full shallow water equations and the kinematic wave approximation. Model parameter values were calibrated in two different watersheds, spanning two orders of magnitude in drainage area. These watersheds were affected by the 2009 Station Fire in the San Gabriel Mountains, CA, USA. Input data for the numerical models were constrained by time series of soil moisture, flow stage, and rainfall collected at field sites, as well as high-resolution lidar-derived digital elevation models. The calibrated parameters were used to model a third watershed in the burn area, and the results show a good match with observed timing of flow peaks. The calibrated roughness parameter (Manning's n) was generally higher when using the kinematic wave approximation relative to the shallow water equations, and decreased with increasing spatial scale. The calibrated effective watershed hydraulic conductivity was low for both models, even for storms occurring several months after the fire, suggesting that wildfire-induced changes to soil-water infiltration were retained throughout that time. Overall, the two model simulations were quite similar suggesting that a kinematic wave model, which is simpler and more computationally efficient, is a suitable approach for predicting flood and debris flow timing in steep, burned watersheds.

  20. Model simulations of flood and debris flow timing in steep catchments after wildfire

    USGS Publications Warehouse

    Rengers, Francis; Mcguire, Luke; Kean, Jason W.; Staley, Dennis M.; Hobley, D.E.J

    2016-01-01

    Debris flows are a typical hazard on steep slopes after wildfire, but unlike debris flows that mobilize from landslides, most post-wildfire debris flows are generated from water runoff. The majority of existing debris-flow modeling has focused on landslide-triggered debris flows. In this study we explore the potential for using process-based rainfall-runoff models to simulate the timing of water flow and runoff-generated debris flows in recently burned areas. Two different spatially distributed hydrologic models with differing levels of complexity were used: the full shallow water equations and the kinematic wave approximation. Model parameter values were calibrated in two different watersheds, spanning two orders of magnitude in drainage area. These watersheds were affected by the 2009 Station Fire in the San Gabriel Mountains, CA, USA. Input data for the numerical models were constrained by time series of soil moisture, flow stage, and rainfall collected at field sites, as well as high-resolution lidar-derived digital elevation models. The calibrated parameters were used to model a third watershed in the burn area, and the results show a good match with observed timing of flow peaks. The calibrated roughness parameter (Manning's $n$) was generally higher when using the kinematic wave approximation relative to the shallow water equations, and decreased with increasing spatial scale. The calibrated effective watershed hydraulic conductivity was low for both models, even for storms occurring several months after the fire, suggesting that wildfire-induced changes to soil-water infiltration were retained throughout that time. Overall the two model simulations were quite similar suggesting that a kinematic wave model, which is simpler and more computationally efficient, is a suitable approach for predicting flood and debris flow timing in steep, burned watersheds.

  1. Flood and Debris Flow Hazard Predictions in Steep, Burned Landscapes

    NASA Astrophysics Data System (ADS)

    Rengers, Francis; McGuire, Luke; Kean, Jason; Staley, Dennis

    2016-04-01

    Post-wildfire natural hazards such as flooding and debris flows threaten infrastructure and can even lead to loss of life. The risk from these natural hazards could be reduced if floods and debris flows could be predicted from modeling. Our ability to test predictive models is primarily constrained by a lack of observational data that can be used for comparison with model predictions. Following the 2009 Station Fire in the San Gabriel Mountains, CA, USA, we conducted a study with high-resolution topography and hydrologic measurements to test the effectiveness of two different hydrologic routing models to predict flood and debris flow timing. Our research focuses on comparing the performance of two hydrologic models with differing levels of complexity and efficiency using high-resolution, lidar-derived digital elevation models. The simpler model uses the kinematic wave approximation to route flows, while the more complex model uses the full shallow water equations. In both models precipitation is spatially uniform and infiltration is simulated using the Green-Ampt infiltration equation. Input data for the numerical models was constrained by time series data of soil moisture, and rainfall collected at field sites as well as high-resolution lidar-derived digital elevation models. We ran the numerical models and varied parameter values for the roughness coefficient and hydraulic conductivity. These parameter values were calibrated by minimizing the difference between the simulated and observed flow timing. Moreover, the two parameters were calibrated in two different watersheds, spanning two orders of magnitude in drainage area. The calibrated parameters were subsequently used to model a third watershed, and the results show a good match with observed timing of flow peaks for both models. Calibrated roughness coefficients are generally higher when using the kinematic wave approximation relative to the full shallow water equations, and decrease with increasing spatial

  2. Sexual Conflict, Life Span, and Aging

    PubMed Central

    Adler, Margo I.; Bonduriansky, Russell

    2014-01-01

    The potential for sexual conflict to influence the evolution of life span and aging has been recognized for more than a decade, and recent work also suggests that variation in life span and aging can influence sexually antagonistic coevolution. However, empirical exploration of these ideas is only beginning. Here, we provide an overview of the ideas and evidence linking inter- and intralocus sexual conflicts with life span and aging. We aim to clarify the conceptual basis of this research program, examine the current state of knowledge, and suggest key questions for further investigation. PMID:24938876

  3. 33 CFR 151.3000 - Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... the purposes of the Marine Debris Research, Prevention, and Reduction Act. 151.3000 Section 151.3000... Definition of Marine Debris for the Purposes of the Marine Debris Research, Prevention, and Reduction Act § 151.3000 Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and...

  4. 33 CFR 151.3000 - Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the purposes of the Marine Debris Research, Prevention, and Reduction Act. 151.3000 Section 151.3000... Definition of Marine Debris for the Purposes of the Marine Debris Research, Prevention, and Reduction Act § 151.3000 Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and...

  5. 33 CFR 151.3000 - Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... the purposes of the Marine Debris Research, Prevention, and Reduction Act. 151.3000 Section 151.3000... Definition of Marine Debris for the Purposes of the Marine Debris Research, Prevention, and Reduction Act § 151.3000 Definition of marine debris for the purposes of the Marine Debris Research, Prevention,...

  6. 33 CFR 151.3000 - Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the purposes of the Marine Debris Research, Prevention, and Reduction Act. 151.3000 Section 151.3000... Definition of Marine Debris for the Purposes of the Marine Debris Research, Prevention, and Reduction Act § 151.3000 Definition of marine debris for the purposes of the Marine Debris Research, Prevention,...

  7. Columbia Debris - Congressman Dave Weldon

    NASA Image and Video Library

    2003-02-20

    Congressman Dave Weldon (second from right) looks over the pieces of Columbia debris stored in the RLV Hangar. At right is Steve Altemus, Space Shuttle test director . Accompanying Weldon are (left toright) Greg Katnick, Grant Case, J.B. Kump and Center Director Roy Bridges. Workers will attempt to reconstruct the orbiter as part of the ongoing investigation of the accident that destroyed the Columbia and claimed the lives of seven astronauts as they returned to Earth after a 16-day research mission, STS-107.

  8. Improved Quantitative Debris Monitoring Capability

    DTIC Science & Technology

    1987-04-01

    voltage increase. A rate increase of the output was expected. The results were inconclusive because the oil contained 12 - r b a large amount of the 10...34ME%7A= - %ZT.ATQf This research was partially funded by the in-house 1 rdt )eri (lent research fund. 𔃻 CCSATI CODIES a S%.9jECT bE~,ohq. n~f...q.-bwrI This report describes the operation and performance evaluation results of a QDmi Mark TI prototype fine ferrous debris monitoring system

  9. The Fast Debris Evolution Model

    NASA Astrophysics Data System (ADS)

    Lewis, Hugh G.; Swinerd, Graham; Newland, Rebecca; Saunders, Arrun

    The ‘Particles-in-a-box' (PIB) model introduced by Talent (1992) removed the need for computerintensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FaDE), employs a first-order differential equation to describe the rate at which new objects (˜ 10 cm) are added and removed from the environment. Whilst Talent (1992) based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FaDE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FaDE model has been implemented as a client-side, web-based service using Javascript embedded within a HTML document. Due to the simple nature of the algorithm, FaDE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ˜ 10 cm low Earth orbit (LEO) debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model. The results demonstrate that the FaDE model is able to capture comparable time-series of collisions and number of objects as predicted by DAMAGE in several scenarios. Further, and perhaps more importantly

  10. Causes of death and life span in Finnish gelsolin amyloidosis.

    PubMed

    Schmidt, Eeva-Kaisa; Atula, Sari; Tanskanen, Maarit; Nikoskinen, Tuuli; Notkola, Irma-Leena; Kiuru-Enari, Sari

    2016-08-01

    Finnish type of hereditary gelsolin amyloidosis (AGel amyloidosis) is an autosomal dominant disorder. Until recently, there has only been little knowledge of fatal complications of the disease and its possible impact on the patients' life span. We identified 272 deceased patients based on patient interviews and genealogical data. After collecting their death certificates, we recorded the patients' underlying and immediate causes of death (CoD) and life span and compared them to the general Finnish population. We then calculated proportional mortality ratios (PMR), standardised for age and sex, for the CoDs. The underlying CoD in 20% of the patients was AGel amyloidosis (PMR = 114.2; 95% CI: 85.6-149.4). The frequency of fatal cancers (10%) was significantly diminished (PMR = 0.47; 95% CI: 0.31-0.69). Renal complications were overrepresented as the immediate CoD in female patients (PMR = 2.82 95% CI: 1.13-5.81). The mean life span for male patients was 73.9 years (95% CI: 72.0-75.6) and 78.0 years for female patients (95% CI: 76.4-79.5) compared to 72.1 and 80.1 years for the general population. Our results suggest that the disease increases the risk of fatal renal complications but does not substantially shorten the life span, possibly due to the significantly lower frequency of fatal cancers. Key Messages AGel amyloidosis may increase the risk of renal complications, especially among female patients. The frequency of fatal cancers is significantly lower. The patients' life span is comparable to that of the general population.

  11. NAAMES-II Expedition: June 1, 201span>6 : Notes from the Field ...

    NASA Website

    August 201span>6; July 201span>6; June 201span>6; May 201span>6; April 201span>6; March 201span>6; February 201span>6; January 201span>6; December 2015; November 2015; October 2015; ...

  12. NAAMES-II Expedition: May 31, 201span>6 : Notes from the Field ...

    NASA Website

    August 201span>6; July 201span>6; June 201span>6; May 201span>6; April 201span>6; March 201span>6; February 201span>6; January 201span>6; December 2015; November 2015; October 2015; ...

  13. High-precision dating and correlation of ice, marine and terrestrial sequences spanning Heinrich Event 3: Testing mechanisms of interhemispheric change using New Zealand ancient kauri (Agathis australis)

    NASA Astrophysics Data System (ADS)

    Turney, Chris S. M.; Palmer, Jonathan; Bronk Ramsey, Christopher; Adolphi, Florian; Muscheler, Raimund; Hughen, Konrad A.; Staff, Richard A.; Jones, Richard T.; Thomas, Zoë A.; Fogwill, Christopher J.; Hogg, Alan

    2016-04-01

    Robustly testing hypotheses of geographic synchroneity of abrupt and extreme change during the late Pleistocene (60,000 to 11,650 years ago) requires a level of chronological precision often lacking in ice, marine and terrestrial sequences. Here we report a bidecadally-resolved New Zealand kauri (Agathis australis) tree-ring sequence spanning two millennia that preserves a record of atmospheric radiocarbon (14C) during ice-rafted debris event Heinrich Event 3 (HE3) in the North Atlantic and Antarctic Isotope Maximum 4 (AIM4) in the Southern Hemisphere. Using 14C in the marine Cariaco Basin and 10Be preserved in Greenland ice, the kauri 14C sequence allows us to precisely align sequences across this period. We observe no significant difference between atmospheric and marine 14C records during HE3, suggesting no stratification of surface waters and collapse in Atlantic Meridional Overturning Circulation (AMOC). Instead our results support recent evidence for a weakened AMOC across at least two millennia of the glacial period. Our work adds to a growing body of literature confirming that Heinrich events are not the cause of stadial cooling and suggests changes in the AMOC were not the primary driver of antiphase temperature trends between the hemispheres. Decadally-resolved 14C in ancient kauri offers a powerful new (and complementary) approach to polar ice core CH4 alignment for testing hypotheses of abrupt and extreme climate change.

  14. Mode localization in multi-span beams

    NASA Technical Reports Server (NTRS)

    Lust, S. D.; Friedmann, P. P.; Bendiksen, O. O.

    1990-01-01

    The influence of numerous effects on mode localization in multi-span beams is investigated. Finite-element methods are used to study localization as a function of: Timoshenko beam effects; beam end conditions; span length, mass, and stiffness imperfection; viscous damping; axial force; transverse support and rotational coupling stiffness; and modeling resolution. Three configurations are studied, commencing with two different two-span models, and culminating in a ten-span configuration resembling lattice-type large space structures. Results indicate that, in addition to the ratio of imperfection to coupling stiffness being an important localization parameter, transverse support stiffness and Timoshenko beam effects greatly affect the tendency of a structure to exhibit localized modes.

  15. Autogenic dynamics of debris-flow fans

    NASA Astrophysics Data System (ADS)

    van den Berg, Wilco; de Haas, Tjalling; Braat, Lisanne; Kleinhans, Maarten

    2015-04-01

    Alluvial fans develop their semi-conical shape by cyclic avulsion of their geomorphologically active sector from a fixed fan apex. These cyclic avulsions have been attributed to both allogenic and autogenic forcings and processes. Autogenic dynamics have been extensively studied on fluvial fans through physical scale experiments, and are governed by cyclic alternations of aggradation by unconfined sheet flow, fanhead incision leading to channelized flow, channel backfilling and avulsion. On debris-flow fans, however, autogenic dynamics have not yet been directly observed. We experimentally created debris-flow fans under constant extrinsic forcings, and show that autogenic dynamics are a fundamental intrinsic process on debris-flow fans. We found that autogenic cycles on debris-flow fans are driven by sequences of backfilling, avulsion and channelization, similar to the cycles on fluvial fans. However, the processes that govern these sequences are unique for debris-flow fans, and differ fundamentally from the processes that govern autogenic dynamics on fluvial fans. We experimentally observed that backfilling commenced after the debris flows reached their maximum possible extent. The next debris flows then progressively became shorter, driven by feedbacks on fan morphology and flow-dynamics. The progressively decreasing debris-flow length caused in-channel sedimentation, which led to increasing channel overflow and wider debris flows. This reduced the impulse of the liquefied flow body to the flow front, which then further reduced flow velocity and runout length, and induced further in-channel sedimentation. This commenced a positive feedback wherein debris flows became increasingly short and wide, until the channel was completely filled and the apex cross-profile was plano-convex. At this point, there was no preferential transport direction by channelization, and the debris flows progressively avulsed towards the steepest, preferential, flow path. Simultaneously

  16. Small Orbital Debris Mitigation Mission Architecture

    NASA Technical Reports Server (NTRS)

    Wiegmann, Bruce M.

    2011-01-01

    Small orbital debris in LEO (1-10 cm in size) presents a clear and present danger to operational LEO spacecraft. This debris field has dramatically increased (nearly doubled) in recent years following the Chinese ASAT Test in 2007 and the Iridium/Cosmos collision in 2009. Estimates of the number of small debris have grown to 500,000 objects after these two events; previously the population was 300,000 objects. These small, untracked debris objects (appproximately 500,000) outnumber the larger and tracked objects (appproximately 20,000) by a factor 25 to 1. Therefore, the risk of the small untracked debris objects to operational spacecraft is much greater than the risk posed by the larger and tracked LEO debris objects. A recent study by The Aerospace Corporation found that the debris environment will increase the costs of maintaining a constellation of government satellites by 5%, a constellation of large commercial satellites by 11%, and a constellation of factory built satellites by 26% from $7.6 billion to $9.57 billion. Based upon these facts, the NASA Marshall Space Flight Center (MSFC) Advanced Concepts Office (ACO) performed an architecture study on Small Orbital Debris Active Removal (SODAR) using a space-based nonweapons- class laser satellite for LEO debris removal. The goal of the SODAR study was to determine the ability of a space-based laser system to remove the most pieces of debris (1 cm to 10 cm, locations unknown), in the shortest amount of time, with the fewest number of spacecraft. The ESA developed MASTER2005 orbital debris model was used to probabilistically classify the future debris environment including impact velocity, magnitude, and directionality. The study ground rules and assumptions placed the spacecraft into a high inclination Low Earth Orbit at 800 km as an initial reference point. The architecture study results found that a spacecraft with an integrated forward-firing laser is capable of reducing the small orbital debris flux within

  17. Sampling supraglacial debris thickness using terrestrial photogrammetry

    NASA Astrophysics Data System (ADS)

    Nicholson, Lindsey; Mertes, Jordan

    2017-04-01

    The melt rate of debris-covered ice differs to that of clean ice primarily as a function of debris thickness. The spatial distribution of supraglacial debris thickness must therefore be known in order to understand how it is likely to impact glacier behaviour, and meltwater contribution to local hydrological resources and global sea level rise. However, practical means of determining debris cover thickness remain elusive. In this study we explore the utility of terrestrial photogrammetry to produce high resolution, scaled and texturized digital terrain models of debris cover exposures above ice cliffs as a means of quantifying and characterizing debris thickness. Two Nikon D5000 DSLRs with Tamron 100mm lenses were used to photograph a sample area of the Ngozumpa glacier in the Khumbu Himal of Nepal in April 2016. A Structure from Motion workflow using Agisoft Photoscan software was used to generate a surface models with <10cm resolution. A Trimble Geo7X differential GPS with Zephyr antenna, along with a local base station, was used to precisely measure marked ground control points to scale the photogrammetric surface model. Measurements of debris thickness along the exposed cliffline were made from this scaled model, assuming that the ice surface at the debris-ice boundary is horizontal, and these data are compared to 50 manual point measurements along the same clifftops. We conclude that sufficiently high resolution photogrammetry, with precise scaling information, provides a useful means to determine debris thickness at clifftop exposures. The resolution of the possible measurements depends on image resolution, the accuracy of the ground control points and the computational capacity to generate centimetre scale surface models. Application of such techniques to sufficiently high resolution imagery from UAV-borne cameras may offer a powerful means of determining debris thickness distribution patterns over debris covered glacier termini.

  18. Space debris, remarks on current legal issues

    NASA Astrophysics Data System (ADS)

    Kerrest, Armel

    2001-10-01

    A legal definition of space debris must take into consideration its consequences on the legal status of the object. For the purpose of mitigation of space debris at the time of the launch, any object launched in outer pace will turn sooner or later into a space debris. For liability purposes, a definition of a "space object " is more useful that the notion of "space debris". It must be sure that every space debris is considered as a space objet according to the liability convention. At the end and certainly a more difficult issue is the qualification of a space object as a space debris when it will be technically feasible to remove it. The question of the property of the debris or object should be important. States are responsible and liable for space debris. According to article VI and VII of the Outer Space Treaty, they must authorise and control any national space activity and make sure these activities will not be conducted against the law. In the case of an accident and excepting the use of nuclear power sources, the main problem lies on damage in outer space to other spacecraft. In that case, the victim must prove a fault. According with the lack of precise rules it should be difficult. It should be necessary to precise the law applicable to space debris. At the domestic level, rules must be taken to prevent space debris through an assessment of risk within the licensing process. At the international level, the principle of an obligation to mitigate debris should be clearly accepted. Some general rules should be useful to avoid breach of competition between commercial actors. The adoption of a clear and precise code of conduct should be of great help because it would determine the good launching States' behaviour and greatly helps the judge appreciating the proof of a fault in case of an accident.

  19. Assessment and prediction of debris-flow hazards

    USGS Publications Warehouse

    Wieczorek, Gerald F.; ,

    1993-01-01

    Study of debris-flow geomorphology and initiation mechanism has led to better understanding of debris-flow processes. This paper reviews how this understanding is used in current techniques for assessment and prediction of debris-flow hazards.

  20. Social network sampling using spanning trees

    NASA Astrophysics Data System (ADS)

    Jalali, Zeinab S.; Rezvanian, Alireza; Meybodi, Mohammad Reza

    2016-12-01

    Due to the large scales and limitations in accessing most online social networks, it is hard or infeasible to directly access them in a reasonable amount of time for studying and analysis. Hence, network sampling has emerged as a suitable technique to study and analyze real networks. The main goal of sampling online social networks is constructing a small scale sampled network which preserves the most important properties of the original network. In this paper, we propose two sampling algorithms for sampling online social networks using spanning trees. The first proposed sampling algorithm finds several spanning trees from randomly chosen starting nodes; then the edges in these spanning trees are ranked according to the number of times that each edge has appeared in the set of found spanning trees in the given network. The sampled network is then constructed as a sub-graph of the original network which contains a fraction of nodes that are incident on highly ranked edges. In order to avoid traversing the entire network, the second sampling algorithm is proposed using partial spanning trees. The second sampling algorithm is similar to the first algorithm except that it uses partial spanning trees. Several experiments are conducted to examine the performance of the proposed sampling algorithms on well-known real networks. The obtained results in comparison with other popular sampling methods demonstrate the efficiency of the proposed sampling algorithms in terms of Kolmogorov-Smirnov distance (KSD), skew divergence distance (SDD) and normalized distance (ND).

  1. Riding a Trail of Debris

    NASA Technical Reports Server (NTRS)

    2005-01-01

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

    This image taken by NASA's Spitzer Space Telescope shows the comet Encke riding along its pebbly trail of debris (long diagonal line) between the orbits of Mars and Jupiter. This material actually encircles the solar system, following the path of Encke's orbit. Twin jets of material can also be seen shooting away from the comet in the short, fan-shaped emission, spreading horizontally from the comet.

    Encke, which orbits the Sun every 3.3 years, is well traveled. Having exhausted its supply of fine particles, it now leaves a long trail of larger more gravel-like debris, about one millimeter in size or greater. Every October, Earth passes through Encke's wake, resulting in the well-known Taurid meteor shower.

    This image was captured by Spitzer's multiband imaging photometer when Encke was 2.6 times farther away than Earth is from the Sun. It is the best yet mid-infrared view of the comet at this great distance. The data are helping astronomers understand how rotating comets eject particles as they circle the Sun.

  2. Orbital Debris Observations with WFCAM

    NASA Technical Reports Server (NTRS)

    Bold, Matthew; Cross, Nick; Irwin, Mike; Kendrick, Richard; Kerr, Thomas; Lederer, Susan; Mann, Robert; Sutorius, Eckhard

    2014-01-01

    The United Kingdom Infrared Telescope has been operating for 35 years on the summit of Mauna Kea as a premier Infrared astronomical facility. In its 35th year the telescope has been turned over to a new operating group consisting of University of Arizona, University of Hawaii and the LM Advanced Technology Center. UKIRT will continue its astronomical mission with a portion of observing time dedicated to orbital debris and Near Earth Object detection and characterization. During the past 10 years the UKIRT Wide Field CAMera (WFCAM) has been performing large area astronomical surveys in the J, H and K bands. The data for these surveys have been reduced by the Cambridge Astronomical Survey Unit in Cambridge, England and archived by the Wide Field Astronomy Unit in Edinburgh, Scotland. During January and February of 2014 the Wide Field CAMera (WFCAM) was used to scan through the geostationary satellite belt detecting operational satellites as well as nearby debris. Accurate photometric and astrometric parameters have been developed by CASU for each of the detections and all data has been archived by WFAU.

  3. Dynamical Processes in Debris Disks

    NASA Astrophysics Data System (ADS)

    Beust, H.

    2010-01-01

    Debris disks are dusty and/or gasous disk that are viewed in scattered light and thermal emission around stars around 107-108 yr. It is well known that the dust in these system is not primodial. It is short lived and must be continuously replenished by colliding planetesimals. Most of them appear distorted by the gravitational pertubations by inner planets or stellar companions. This is why these systems are viewed today as young planetary systems. Debris disks are collisional systems. Thanks to collisional cascade towards smaller size, the dust particles are transported outwards by radiation or stellar wind pressure. Below a given blow-off size they escape the system. This model explains the radial density profiles observed. The various asymmetries, clumps and other dynamical structures such as spiral arms are though to originate in gravitational perturbations by planets and/or companions. Planets usually create gaps in disks, but they also sculpt disks via their mean-motion resonances. Clumpy structures are often invoked as resulting from such an interaction. Stellar companions usually truncate the disk, sometimes confining them to thin annular structures. They also help creating spiral patterns, either tidally or by secular interaction. In this context, the situation is different whether the perturbing companions are bound or just passing stars. In any case, dynamical studies (often specific to each system) can greatly help constraining the configuration and the past history of these systems.

  4. Two-temperature Debris Disks: Signposts for Directly Imaged Planets?

    NASA Astrophysics Data System (ADS)

    Kennedy, Grant M.; Wyatt, Mark C.

    2016-01-01

    This work considers debris disks whose spectra can be modelled by dust emission at two different temperatures. These disks are typically assumed to be a sign of multiple belts, but only a few cases have been confirmed via high resolution observations. We derive the properties of a sample of two-temperature disks, and explore whether this emission can arise from dust in a single narrow belt. While some two-temperature disks arise from single belts, it is probable that most have multiple spatial components. These disks are plausibly similar to the outer Solar System's configuration of Asteroid and Edgeworth-Kuiper belts separated by giant planets. Alternatively, the inner component could arise from inward scattering of material from the outer belt, again due to intervening planets. For either scenario, the ratio of warm/cool component temperatures is indicative of the scale of outer planetary systems, which typically span a factor of about ten in radius.

  5. Formation Flying Guidance for Space Debris Observation, Manipulation and Capture

    NASA Astrophysics Data System (ADS)

    Peters, Thomas V.

    This article provides a brief overview of the space debris population, debris attitude dynamics, technologies for debris removal, followed by a more in-depth discussion of robotic arm based capture of debris. Guidance aspects of active debris removal missions are discussed. Mission phases for active debris removal missions are rendezvous, inspection, attitude synchronization and capture and de-tumbling. The need for attitude synchronization is driven by recent observations of Envisat which exhibits a fairly high rotation rate.

  6. Estimates of current debris from flux models

    SciTech Connect

    Canavan, G.H.

    1997-01-01

    Flux models that balance accuracy and simplicity are used to predict the growth of space debris to the present. Known and projected launch rates, decay models, and numerical integrations are used to predict distributions that closely resemble the current catalog-particularly in the regions containing most of the debris.

  7. STS-107 Columbia debris reconstruction team

    NASA Image and Video Library

    2002-02-12

    Astronauts Lee Archambault and Joan Higginbotham look at a piece of Columbia debris placed on the grid in the RLV Hangar. The debris was shipped from Barksdale Air Force Base, Shreveport, La. As part of the ongoing investigation into the tragic accident, workers will attempt to reconstruct the orbiter inside the RLV.

  8. STS-107 Columbia debris reconstruction team

    NASA Image and Video Library

    2002-02-12

    Shuttle Program Manager Ron Dittemore (leaning over) examines a piece of Columbia debris in the RLV Hangar. The debris was shipped from the collection point at Barksdale Air Force Base, Shreveport, La. As part of the ongoing investigation into the tragic accident that claimed Columbia and her crew of seven, workers will attempt to reconstruct the orbiter inside the RLV.

  9. STS-107 Columbia debris reconstruction team

    NASA Image and Video Library

    2002-02-12

    The reconstruction team checks out the Columbia debris after it was offloaded at the RLV Hangar. The debris was shipped from Barksdale Air Force Base, Shreveport, La. As part of the ongoing investigation into the tragic accident, workers will attempt to reconstruct the orbiter inside the RLV.

  10. STS-107 Columbia debris reconstruction team

    NASA Image and Video Library

    2002-02-12

    A worker examines a piece of the Columbia debris on the floor of the RLV Hangar. The debris was shipped from Barksdale Air Force Base, Shreveport, La. As part of the ongoing investigation into the tragic accident, workers will attempt to reconstruct the orbiter inside the RLV.

  11. STS-107 Columbia debris reconstruction team

    NASA Image and Video Library

    2002-02-12

    Members of the reconstruction team check out the Columbia debris inside the RLV Hangar. The debris was shipped from Barksdale Air Force Base, Shreveport, La. As part of the ongoing investigation into the tragic accident, workers will attempt to reconstruct the orbiter inside the RLV.

  12. A high severity space hazard - Orbital debris

    NASA Technical Reports Server (NTRS)

    Bahr, G. K.; Disimile, P. J.

    1990-01-01

    This paper examines the orbital debris-meteoroid hazard that will be encountered by the Space Station Freedom. Recent reports on the orbital debris studies are discussed with special attention given to the procedures and techniques that can be used to minimize the impact damage, to avoid the collision, and to design shielding distribution so as to reduce the penetration damage.

  13. Interagency Report on Orbital Debris, 1995

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This 1995 report updates the findings and recommendations of the 1989 report and reflects the authors' progress in understanding and managing the orbital debris environment. It provides an up-to-date portrait of their measurement, modeling, and mitigation efforts; and a set of recommendations outlining specific steps they should pursue, both domestically and internationally, to minimize the potential hazard posed by orbital debris.

  14. Reflectance Spectra of Space Debris in GEO

    NASA Astrophysics Data System (ADS)

    Schildknecht, T.; Vannanti, A.; Krag, H.; Erd, C.

    The space debris environment in the Geostationary Earth Orbit (GEO) region is mostly investigated by means of optical surveys. Such surveys revealed a considerable amount of debris in the size range of 10 centimeter to one meter. Some of these debris exhibit particularly high area-to-mass ratios as derived from the evolution of their orbits. In order to understand the nature and eventually the origin of these objects, observations allowing to derive physical characteristics like size, shape and material are required. Information on the shape and the attitude motion of a debris piece may be obtained by photometric light curves. The most promising technique to investigate the surface material properties is reflectance spectroscopy. This paper discusses preliminary results obtained from spectrometric observations of space debris in GEO. The observations were acquired at the 1-meter ESA Space Debris Telescope (ESASDT) on Tenerife with a low-resolution spectrograph in the wavelength range of 450-960 nm. The target objects were space debris of different types with brightness as small as magnitude 15. Some simple-shaped, intact "calibration objects" with known surface materials like the MSG-2 satellites were also observed. The spectra show shape variations expected to be caused by the different physical properties of the objects. The determination of the possible materials is still in a preliminary phase. Limitations of the acquisition process of the spectra and the subsequent analysis are discussed. Future steps planned for a better characterization of the debris from the observed data are briefly outlined.

  15. Calculation of average landslide frequency using climatic records

    Treesearch

    L. M. Reid

    1998-01-01

    Abstract - Aerial photographs are used to develop a relationship between the number of debris slides generated during a hydrologic event and the size of the event, and the long-term average debris-slide frequency is calculated from climate records using the relation.

  16. Development of the Space Debris Sensor (SDS)

    NASA Technical Reports Server (NTRS)

    Hamilton, Joe; Liou, J. -C.; Anz-Meador, P.; Matney, M.; Christiansen, E.

    2017-01-01

    Debris Resistive/Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) is an impact sensor designed to detect and characterize collisions with small orbital debris: from 50 microns to greater than 1millimeter debris size detection; Characterizes debris size, speed, direction, and density. The Space Debris Sensor (SDS) is a flight demonstration of DRAGONS on the International Space Station: Approximately 1 square meter of detection area facing the ISS velocity vector; Minimum two year mission on Columbus External Payloads Facility (EPF); Minimal obstruction from ISS hardware; Development is nearing final checkout and integration with the ISS; Current launch schedule is SpaceX13, about September 2017, or SpaceX14, about Jan 2018.

  17. Debris flows: behavior and hazard assessment

    USGS Publications Warehouse

    Iverson, Richard M.

    2014-01-01

    Debris flows are water-laden masses of soil and fragmented rock that rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form lobate deposits when they spill onto valley floors. Because they have volumetric sediment concentrations that exceed 40 percent, maximum speeds that surpass 10 m/s, and sizes that can range up to ~109 m3, debris flows can denude slopes, bury floodplains, and devastate people and property. Computational models can accurately represent the physics of debris-flow initiation, motion and deposition by simulating evolution of flow mass and momentum while accounting for interactions of debris' solid and fluid constituents. The use of physically based models for hazard forecasting can be limited by imprecise knowledge of initial and boundary conditions and material properties, however. Therefore, empirical methods continue to play an important role in debris-flow hazard assessment.

  18. Aquatic Debris Detection Using Embedded Camera Sensors

    PubMed Central

    Wang, Yong; Wang, Dianhong; Lu, Qian; Luo, Dapeng; Fang, Wu

    2015-01-01

    Aquatic debris monitoring is of great importance to human health, aquatic habitats and water transport. In this paper, we first introduce the prototype of an aquatic sensor node equipped with an embedded camera sensor. Based on this sensing platform, we propose a fast and accurate debris detection algorithm. Our method is specifically designed based on compressive sensing theory to give full consideration to the unique challenges in aquatic environments, such as waves, swaying reflections, and tight energy budget. To upload debris images, we use an efficient sparse recovery algorithm in which only a few linear measurements need to be transmitted for image reconstruction. Besides, we implement the host software and test the debris detection algorithm on realistically deployed aquatic sensor nodes. The experimental results demonstrate that our approach is reliable and feasible for debris detection using camera sensors in aquatic environments. PMID:25647741

  19. Development of the Space Debris Sensor

    NASA Technical Reports Server (NTRS)

    Hamilton, J.; Liou, J.-C.; Anz-Meador, P. D.; Corsaro, B.; Giovane, F.; Matney, M.; Christiansen, E.

    2017-01-01

    The Space Debris Sensor (SDS) is a NASA experiment scheduled to fly aboard the International Space Station (ISS) starting in 2017. The SDS is the first flight demonstration of the Debris Resistive/Acoustic Grid Orbital NASA-Navy Sensor (DRAGONS) developed and matured by the NASA Orbital Debris Program Office. The DRAGONS concept combines several technologies to characterize the size, speed, direction, and density of small impacting objects. With a minimum two-year operational lifetime, SDS is anticipated to collect statistically significant information on orbital debris ranging from 50 micron to 500 micron in size. This paper describes the SDS features and how data from the ISS mission may be used to update debris environment models. Results of hypervelocity impact testing during the development of SDS and the potential for improvement on future sensors at higher altitudes will be reviewed.

  20. The debris-flow rheology myth

    USGS Publications Warehouse

    Iverson, R.M.; ,

    2003-01-01

    Models that employ a fixed rheology cannot yield accurate interpretations or predictions of debris-flow motion, because the evolving behavior of debris flows is too complex to be represented by any rheological equation that uniquely relates stress and strain rate. Field observations and experimental data indicate that debris behavior can vary from nearly rigid to highly fluid as a consequence of temporal and spatial variations in pore-fluid pressure and mixture agitation. Moreover, behavior can vary if debris composition changes as a result of grain-size segregation and gain or loss of solid and fluid constituents in transit. An alternative to fixed-rheology models is provided by a Coulomb mixture theory model, which can represent variable interactions of solid and fluid constituents in heterogeneous debris-flow surges with high-friction, coarse-grained heads and low-friction, liquefied tails. ?? 2003 Millpress.

  1. Spatial Density Evolution of Space Debris Environment

    NASA Astrophysics Data System (ADS)

    Li, Canan; Pang, Baojun; Ding, Li

    2009-03-01

    It is known that the space debris provide great risks to the safety of on-orbit space vehicles, which makes it necessary to establish a model to evaluate their impact risks. In order to provide the scenario of the future space debris environment for space vehicle designers, this paper addresses a simplified mathematical model for the future evolution of space debris environment. While the spatial density is of more concern to engineers, this paper is devoted to study the evolution of the distribution of spatial density of space debris. Given the initial spatial density, this paper develops the algorithm to obtained the spatial density of space debris at any moment of future, by considering the orbital propagation and collisions.

  2. Development of the Space Debris Sensor (SDS)

    NASA Technical Reports Server (NTRS)

    Hamilton, J.; Liou, J.-C.; Anz-Meador, P. D.; Corsaro, B.; Giovane, F.; Matney, M.; Christiansen, E.

    2017-01-01

    The Space Debris Sensor (SDS) is a NASA experiment scheduled to fly aboard the International Space Station (ISS) starting in 2018. The SDS is the first flight demonstration of the Debris Resistive/Acoustic Grid Orbital NASA-Navy Sensor (DRAGONS) developed and matured at NASA Johnson Space Center's Orbital Debris Program Office. The DRAGONS concept combines several technologies to characterize the size, speed, direction, and density of small impacting objects. With a minimum two-year operational lifetime, SDS is anticipated to collect statistically significant information on orbital debris ranging from 50 microns to 500 microns in size. This paper describes the features of SDS and how data from the ISS mission may be used to update debris environment models. Results of hypervelocity impact testing during the development of SDS and the potential for improvement on future sensors at higher altitudes will be reviewed.

  3. Molecular Gas In Young Debris Disks

    NASA Astrophysics Data System (ADS)

    Moór, Attila

    2016-07-01

    Debris disks are generally thought to be the gas poor descendants of protoplanetary disks. While this characteristic may be true for most debris systems, recent surveys in rotational transitions of carbon monoxide led to a growing sample of debris disks where gas has been detected. The origin of gas in these disks is unclear yet. It may be secondary, i.e., similarly to dust grains it is continuously replenished via erosion of larger bodies. However, because of their youth, one cannot exclude that some disks may be hybrid in the sense that they retain their residual primordial gas, while the dust component may predominantly be second generation. The first observations of gaseous debris disks with ALMA provided examples of both types. This talk will review the currently known CO-rich debris disks with special emphasis on the origin of gas and on the commonly shared disk/host star properties.

  4. Dynamics of Debris Supply and Removal from Coastal Cliffs

    NASA Astrophysics Data System (ADS)

    Dickson, M. E.; Vann Jones, E. C.; Payo, A.; Matsumoto, H.

    2016-12-01

    Progress in obtaining a morphodynamic understanding of rocky shores has been limited by slow rates of change and lack of preserved evidence of erosion processes. As a result we do not have a detailed understanding of the relative contributions of failure events across the magnitude-frequency spectrum. This talk describes field experiments, supported by simple stock-flow modelling, on a coastal cliff-face in eastern New Zealand. Key features of this site are that it is composed of near-homogenous rapidly eroding mudstone, and it is fronted by a wide intertidal rock platform that results in the cliff toe being exposed to waves every high tide. Several techniques were used to measure the cliff debris supply-removal system. Sediment traps at the cliff toe directly recorded rates of debris supply from the cliff-face at five discrete locations. Repeated high-resolution terrestrial laser scans over several consecutive low-tide stages documented changes in cliff-toe talus volumes along 50m of shoreline. Optical back-scatter sensors located on the rock shore platform in front of the cliff toe constrained the timing of talus-debris resuspension during tidal inundation of the cliff toe. Wave pressure gauges were used to characterise the wave field acting on the cliff. Results demonstrate that high-resolution (<5mm) laser scanning can meaningfully characterise rates of coastal cliff erosion at the very high-frequency low-magnitude end of the erosion spectrum. We find that rates of debris supply from the cliff face are dependent on the subaerial weathering system, in particular wetting and drying and associated expansion and contraction of clay minerals within the cliff rock. Rates of debris removal from the cliff toe depend on tide and wave conditions: even under low wave-energy conditions, waves at infragravity frequencies can access the cliff toe at high tide leading to sediment suspension. We explore the basic feedback structure of cliff, talus and debris removal using a

  5. In-situ Observations of Space Debris at ESA

    NASA Astrophysics Data System (ADS)

    Drolshagen, G.

    Information on the small size (millimetre or smaller) space debris and meteoroid population in space can only be obtained by in-situ detectors or the analysis of retrieved hardware. Past, ongoing and planned ESA activities in this field are presented. In 1996 the GORID impact detector was launched into a geostationary orbit on-board the Russian Express-2 telecommunication satellite. This impact ionisation detector had a sensor surface of 0.1 m2. Until July 2002 when the spacecraft was shut down it recorded more than 3000 impacts in the micrometre size range. Inter alia, GORID measured numerous clusters of events, believed to result from debris clouds, and indicated that debris fluxes in GEO are larger than predicted by present models. Another in-situ detector, DEBIE-1, was launched in October 2001 and is operating on-board the small technology satellite PROBA in a low polar orbit. It has two sensors, each of 0.01m2 size, pointing in different directions. A second detector of this type, DEBIE-2 with 3 sensors, is ready for flight on the EuTEF carrier (external payload to ISS). The data from GORID and DEBIE-1 are stored on-line in EDID (European Detector Impact Database). Post-flight impact analyses of retrieved hardware provide detailed information on the encountered meteoroid and debris fluxes over a large range of sizes. ESA initiated several analyses in the past ((EURECA, Hubble Space Telescope (HST) solar arrays). The most recent impact analysis was performed for the HST solar arrays retrieved in March 2002. Measured crater sizes in solar cells ranged from about 1 micron to 7 mm. A total of 175 complete penetrations of the 0.7 mm thick arrays were observed. A chemical analysis of impact residues allowed the distinction between space debris and natural meteoroids. Space debris was found to dominate for sizes smaller than 10 microns and larger than about 1 mm. For intermediate sizes impacts are mainly from meteoroids. Results of the analysis and comparisons with

  6. Fate of debris from the Borealis basin impact on Mars and from the formation of the Earth-Moon system

    NASA Astrophysics Data System (ADS)

    Asphaug, Erik; Jackson, Alan P.; Gabriel, Travis; Minton, David A.; Hesselbrock, Andrew

    2016-10-01

    Giant planet-forming collisions can inject significant amounts of debris into the inner solar system. Dynamically the fate of this debris is primarily to re-impact the target body and the other terrestrial planets, defining a post-giant-impact epoch. Giant impact debris leave signatures on the surfaces of terrestrial bodies, influencing and perhaps dominating their early cratering record, and for the largest giant impacts, to intensive surface evolution and even changes in bulk crustal material composition. We use high-resolution N-body simulations to study the fate of debris released by specific giant impacts suggested to have formed the Borealis basin on Mars, and compare it to the fate of debris released by giant impact scenarios for Earth's Moon. We consider how the velocity dependence of Earth-Moon accretion leads to differing velocity distributions of debris-impactors for Earth and Moon, and thus different crater distributions, and study how different assumptions on the size distribution of debris effects these results. We also investigate the influence of collisional grinding within the debris distribution, and the possibility of trapped populations.

  7. Geosynchronous Large Debris Reorbiter: Challenges and Prospects

    NASA Astrophysics Data System (ADS)

    Schaub, Hanspeter; Moorer, Daniel F.

    2012-06-01

    An elegant solution is proposed to an old problem of how to remove expired or malfunctioning satellites from the geosynchronous belt. Previous "space-tug" concepts describe a scenario where one craft (the tug) docks with another (debris) and then boosts that object to a super-synchronous orbit. The most challenging aspect of these concepts is the very complex proximity operations to an aging, possibly rotating and, probably, non-cooperative satellite. Instead, the proposed method uses an elegant blend of electrostatic charge control and low-thrust propulsion to avoid any contact requirement. The Geosynchronous Large Debris Reorbiter (GLiDeR) uses active charge emission to raise its own absolute potential to 10's of kilovolts and, in addition, directs a stream of charged particles at the debris to increase its absolute potential. In a puller configuration the opposite polarity of the debris creates an attractive force between the GLiDeR and the debris. Pusher configurations are feasible as well. Next, fuel-efficient micro-thrusters are employed to gently move the reorbiter relative to the debris, and then accelerate the debris out of its geosynchronous slot and deposit it in a disposal orbit. Preliminary analysis shows that a 1000 kg debris object can be re-orbited over two-four months. During the reorbit phase the separation distance is held nominally fixed without physical contact, even if the debris is tumbling, by actively controlling the charge transfer between the reorbiter and the debris. Numerical simulations are presented illustrating the expected performance, taking into account also the solar radiation pressure.

  8. Component Analysis of Simple Span vs. Complex Span Adaptive Working Memory Exercises: A Randomized, Controlled Trial

    PubMed Central

    Gibson, Bradley S.; Kronenberger, William G.; Gondoli, Dawn M.; Johnson, Ann C.; Morrissey, Rebecca A.; Steeger, Christine M.

    2012-01-01

    There has been growing interest in using adaptive training interventions such as Cogmed-RM to increase the capacity of working memory (WM), but this intervention may not be optimally designed. For instance, Cogmed-RM can target the primary memory (PM) component of WM capacity, but not the secondary memory (SM) component. The present study hypothesized that Cogmed-RM does not target SM capacity because the simple span exercises it uses may not cause a sufficient amount of information to be lost from PM during training. To investigate, we randomly assigned participants to either a standard (simple span; N = 31) or a modified (complex span; N = 30) training condition. The main findings showed that SM capacity did not improve, even in the modified training condition. Hence, the potency of span-based WM interventions cannot be increased simply by converting simple span exercises into complex span exercises. PMID:23066524

  9. Calendar life-span versus fission life-span of Paramecium aurelia.

    PubMed

    Smith-Sonneborn, J; Reed, J C

    1976-01-01

    The hypothesis that paramecia use fissions, not days, to measure length of cell life-span was investigated. Parallel cell lines were grown at 27 C and at 24 C. The daily fission rate of the cells at 24 C was lower than at 27 C. If the cells count fissions, not days, the life-span in fissions should remain unchanged, whereas the cell life-span in days should increase in the lines with reduced daily fission rate. The results showed a significant increase in cell life-span in days when the cells were cultivated for 70-100% of their life cycle at 24 C. The life-span as measured by fissions, however, remained unchanged regardless of the time of the life cycle when cells were shifted to 24 C. The data indicate that, as a model system for cellular aging, paramecia are comparable to cells which use cell doublings to measure life-span.

  10. Improving The Near-Earth Meteoroid And Orbital Debris Environment Definition With LAD-C

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Giovane, F. J.; Corsaro, R. C.; Burchell, M. J.; Drolshagen, G.; Kawai, H.; Tabata, M.; Stansbery, E. G.; Westphal, A. J.; Yano, H.

    2006-01-01

    To improve the near-Earth meteoroid and orbital debris environment definition, a large area particle sensor/collector is being developed to be placed on the International Space Station (ISS). This instrument, the Large Area Debris Collector (LAD-C), will attempt to record meteoroid and orbital debris impact flux, and capture the same particles with aerogel. After at least one year of deployment, the whole system will be brought back for additional laboratory analysis of the captured meteoroids and orbital debris. This project is led by the U.S. Naval Research Laboratory (NRL) while the U.S. Department of Defense (DoD) Space Test Program (STP) is responsible for the integration, deployment, and retrieval of the system. Additional contributing team members of the consortium include the NASA Orbital Debris Program Office, JAXA Institute of Space and Astronautical Science (ISAS), Chiba University (Japan), ESA Space Debris Office, University of Kent (UK), and University of California at Berkeley. The deployment of LAD-C on the ISS is planned for 2008, with the system retrieval in late 2009.

  11. Plastic debris in the Mediterranean Sea: Types, occurrence and distribution along Adriatic shorelines.

    PubMed

    Munari, Cristina; Scoponi, Marco; Mistri, Michele

    2017-09-01

    Small plastic debris in sediments from five beaches were investigated to evaluate their occurrence and abundance in the Northern Adriatic coast for the first time. Plastic debris extracted from sediments were counted, weighted and identified by Fourier-transform infrared spectroscopy (FT-IR). A total of 1345 items of debris (13.491g) were recorded, with a mean density of 12.1 items kg(-1) d.w. and 0.12gkg(-1) d.w. Fragments were the most frequent type of small plastics debris detected. In terms of abundance, microplastics (<5mm) accounted for 61% of debris, showing their wide distribution on Adriatic coasts, even far-away from densely populated areas. The majority of the polymers found were polyolefins: there were greater quantities of polyethylene and polypropylene compared to other types of plastic. Primary microplastics accounted for only 5.6% of the total plastic debris. There were greater quantities of microplastics at sites subjected to stronger riverine runoff. The results will provide useful background information for further investigations to understand the sink and sources of this emergent and priority contaminant. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Processing the ground vibration signal produced by debris flows: the methods of amplitude and impulses compared

    NASA Astrophysics Data System (ADS)

    Arattano, M.; Abancó, C.; Coviello, V.; Hürlimann, M.

    2014-12-01

    Ground vibration sensors have been increasingly used and tested, during the last few years, as devices to monitor debris flows and they have also been proposed as one of the more reliable devices for the design of debris flow warning systems. The need to process the output of ground vibration sensors, to diminish the amount of data to be recorded, is usually due to the reduced storing capabilities and the limited power supply, normally provided by solar panels, available in the high mountain environment. There are different methods that can be found in literature to process the ground vibration signal produced by debris flows. In this paper we will discuss the two most commonly employed: the method of impulses and the method of amplitude. These two methods of data processing are analyzed describing their origin and their use, presenting examples of applications and their main advantages and shortcomings. The two methods are then applied to process the ground vibration raw data produced by a debris flow occurred in the Rebaixader Torrent (Spanish Pyrenees) in 2012. The results of this work will provide means for decision to researchers and technicians who find themselves facing the task of designing a debris flow monitoring installation or a debris flow warning equipment based on the use of ground vibration detectors.

  13. The influence of supraglacial debris on proglacial runoff fluctuations and water chemistry

    NASA Astrophysics Data System (ADS)

    Fyffe, Catriona; Brock, Ben; Kirkbride, Martin; Black, Andrew; Smiraglia, Claudio; Diolaiuti, Guglielmina

    2016-04-01

    This paper seeks to explore how the debris' influence on glacial ablation, topography and drainage structure impacts on the water chemistry and runoff signal of the proglacial stream. This was achieved through analysis of the supraglacial and proglacial water chemistry and the proglacial hydrograph of Miage Glacier, Western Italian Alps. Although the supraglacial water chemistry was influenced by the debris, there was also evidence that the less efficient hydrological system beneath the debris-covered lower tongue also increased the ion concentration of the proglacial stream. Compared to published data for clean glaciers, fewer diurnally classified daily hydrographs were found in the proglacial discharge record, with the amplitude of the diurnal signal peaking later and being relatively low in amplitude. These hydrograph characteristics were thought due to the debris' attenuation of the melt signal, and the smaller input streams and less efficient subglacial drainage system beneath the debris-covered lower tongue. Warmer than average weather conditions were required for strongly diurnal hydrographs to be shown, with a 'saw-toothed' hydrograph shown under average conditions. The diurnal relationship between conductivity and discharge often demonstrated anti-clockwise hysteresis, indicating that the more rapidly routed dilute melt component from the mid-glacier peaked before the peak in discharge. Components from higher up glacier and the lower debris-covered tongue likely had longer transit times and reached the proglacial stream later.

  14. Beach debris in the Azores (NE Atlantic): Faial Island as a first case study.

    PubMed

    Pieper, Catharina; Ventura, Maria A; Martins, Ana; Cunha, Regina T

    2015-12-30

    Marine debris is widely recognised as a global environmental problem. This study assesses density, type, and temporal trends of marine debris in two sandy beaches of Faial Island (Azores, NE-Atlantic). During seven months (six days per month) the beaches were surveyed by performing 10 random transects at each site. Recorded items within the range 2-30 cm were organised into seven categories. Densities of total debris varied from 0 to 1.940 items m(-2), with plastics dominating both areas. Both beaches, presented the highest debris abundance in February, most probably related to prevailing winds and swell. Location and/or time of year also seemed to influence the type of debris present. These findings provide new insights into debris accumulation rates in the Azores, where no previous studies were made. It also confirms the global trend of increased plastics accumulation on shorelines, highlighting the need for further research in remote islands. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Span graphics display utilities handbook, first edition

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Green, J. L.; Newman, R.

    1985-01-01

    The Space Physics Analysis Network (SPAN) is a computer network connecting scientific institutions throughout the United States. This network provides an avenue for timely, correlative research between investigators, in a multidisciplinary approach to space physics studies. An objective in the development of SPAN is to make available direct and simplified procedures that scientists can use, without specialized training, to exchange information over the network. Information exchanges include raw and processes data, analysis programs, correspondence, documents, and graphite images. This handbook details procedures that can be used to exchange graphic images over SPAN. The intent is to periodically update this handbook to reflect the constantly changing facilities available on SPAN. The utilities described within reflect an earnest attempt to provide useful descriptions of working utilities that can be used to transfer graphic images across the network. Whether graphic images are representative of satellite servations or theoretical modeling and whether graphics images are of device dependent or independent type, the SPAN graphics display utilities handbook will be the users guide to graphic image exchange.

  16. Sediment storage and evacuation in headwater valleys at the transition between debris-flow and fluvial processes

    NASA Astrophysics Data System (ADS)

    Lancaster, Stephen T.; Casebeer, Nathan E.

    2007-11-01

    Sediment from landscape disturbance often enters temporary storage in valleys and evacuates over longer times, which in steeplands are poorly delimited. We hypothesize that, across process transitions (e.g., debris flow versus fluvial transport), distributions of sediment transit times also change. We use field surveys and extensive radiocarbon dating to assess the distribution of transit (residence) times through the proxy measurement of ages of bank deposits in two mainstem reaches of a 2.23 km2 watershed in the Oregon Coast Range. In the downstream reach, debris fans impound fluvial deposits; debris-flow, fine fluvial, and coarse fluvial deposits compose nearly equal parts of the valley fill; and fluvial erosion evacuates deposits. Transit times have a sample mean of 1.22 × 103 14C yr and an exponential distribution, indicating uniform probability of evacuation from storage. In the upstream reach, valley-spanning debris jams impound debris-flow deposits composing >95% of the valley fill, which is routinely scoured by debris flows. Transit times have a sample mean of 4.43 × 102 14C yr and, if >100 14C yr, a power-law distribution, indicating preferential evacuation of younger deposits and retention of older deposits. In both reaches, most sediment has short transit times (<600 14C yr), but significant volumes remain for millennia. Less than 20% of basin-wide denudation passes through these reservoirs, but the latter are still significant buffers between hillslope disturbance and downstream aquatic habitat, especially for coarse sediment.

  17. Erosion of steepland valleys by debris flows

    USGS Publications Warehouse

    Stock, J.D.; Dietrich, W.E.

    2006-01-01

    Episodic debris flows scour the rock beds of many steepland valleys. Along recent debris-flow runout paths in the western United States, we have observed evidence for bedrock lowering, primarily by the impact of large particles entrained in debris flows. This evidence may persist to the point at which debris-flow deposition occurs, commonly at slopes of less than ???0.03-0.10. We find that debris-flow-scoured valleys have a topographic signature that is fundamentally different from that predicted by bedrock river-incision models. Much of this difference results from the fact that local valley slope shows a tendency to decrease abruptly downstream of tributaries that contribute throughgoing debris flows. The degree of weathering of valley floor bedrock may also decrease abruptly downstream of such junctions. On the basis of these observations, we hypothesize that valley slope is adjusted to the long-term frequency of debris flows, and that valleys scoured by debris flows should not be modeled using conventional bedrock river-incision laws. We use field observations to justify one possible debris-flow incision model, whose lowering rate is proportional to the integral of solid inertial normal stresses from particle impacts along the flow and the number of upvalley debris-flow sources. The model predicts that increases in incision rate caused by increases in flow event frequency and length (as flows gain material) downvalley are balanced by rate reductions from reduced inertial normal stress at lower slopes, and stronger, less weathered bedrock. These adjustments lead to a spatially uniform lowering rate. Although the proposed expression leads to equilibrium long-profiles with the correct topographic signature, the crudeness with which the debris-flow dynamics are parameterized reveals that we are far from a validated debris-flow incision law. However, the vast extent of steepland valley networks above slopes of ???0.03-0.10 illustrates the need to understand debris

  18. Lessons Learned from Natural Space Debris in Heliocentric Orbit: An Analogue for Hazardous Debris in Earth Orbit

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Wei, Hanying; Connors, Martin; Lai, Hairong; Delzanno, Gian Luca

    Interplanetary Field Enhancements (IFEs) were discovered almost 30 years ago in the PVO magnetic-field records. Our current understanding is that IFEs result from interactions between solar wind and clouds of nanometer-scale charged dust released in interplanetary collisions. These charged dust clouds are then accelerated by the solar wind and moving away from the Sun at near solar wind speed and detected by spacecraft in heliocentric orbit. The dynamics of the debris in heliocentric orbit is analogous to that mankind has placed into Earth orbit. There are lessons here that are worth exploring. The IFE formation hypothesis was supported by the discovery of co-orbiting materials associated with asteroid 2201 Oljato: IFE rate peaked when Oljato was close and IFE occurrence clustered in the longitudes near which the orbit of Oljato intersects the orbital plane of Venus. A followed up study with Venus Express observations suggested that the co-orbiting materials dissipated in 30 years. An important aspect of this evolution is that at collisional speeds of 20 km/s, a small body can destroy one 106 times more massive. This destruction of large debris by small debris could also be important in the evolution of the terrestrial debris. At 1AU, based on ACE and Wind observations, IFEs have a significant cluster in the longitude range between 195° and 225°. Thus we use the same IFE technique to identify the ‘parent’ Near-Earth Objects of co-orbiting materials which should be responsible for those IFEs. There are more than 5000 JPL documented NEOs whose ecliptic plane crossings are near to or inside the Earth’s orbit and whose orbital periods are less than five years. By comparing their trajectories, we find that the asteroid 138175 is a good candidate for the ‘parent’ body. This asteroid orbits the Sun in a 5.24° inclined elliptical orbit with a period of 367.96 days. Its descending node is at about 206°, where the IFE occurrence rate peaks. We also find that

  19. Listening to debris flows: What can ground vibrations tell us about debris-flow entrainment and flow density?

    NASA Astrophysics Data System (ADS)

    Kean, J. W.; Coe, J. A.; Coviello, V.; Smith, J. B.; McCoy, S. W.; Arattano, M.

    2015-12-01

    Debris flows generate seismic waves as they travel downslope and can grow in size and destructive potential by entraining sediment along their paths. Recent observations from the Chalk Cliffs monitoring site in central Colorado show there is a systematic relation between the magnitude of seismic waves and both (1) the amount of erodible sediment beneath the flow, and (2) the density of the flow. Specifically, we observed that the spectral power of debris-flow induced ground motion increased by two orders of magnitude after a 34-cm layer of bed sediment was eroded from a bedrock channel. We also observed that high-density (sediment-rich) debris-flow surges generate about two orders of magnitude greater spectral power than low-density (water-rich) surges of similar thickness. These observations lead us to the hypothesis that the recorded ground motions are generated primarily by the impacts of grains on bedrock sections of the channel. This hypothesis is supported by ball drop tests which showed that impacts on deformable loose bed sediment in the channel (if present) generate negligibly small surface waves compared to impacts on bedrock. We thus expect debris-flow induced ground motion to increase as sediment entrainment exposes bedrock in channel, and as the flow density (and number of grains) increase. We explored the connection between ground motions and debris-flow entrainment/density by adapting a model from fluvial seismology [Tsai et al., GRL, 2012]. We used the adapted model to estimate rates of sediment entrainment and the density of flows over bare bedrock channels. Our estimates of sediment entrainment compared favorably with previous direct measurements of entrainment rates at the site. Estimates of flow density are sufficiently accurate to distinguish between three density levels: low (<1200 kg/m3), medium (1200-1600 kg/m3), and high (<1600 kg/m3). Although more testing is needed, these initial results suggest the approach may be a new indirect way to

  20. The Technology of Modeling Debris Cloud Produced by Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Ma, Zhaoxia; Huang, Jie; Liang, Shichang; Zhou, Zhixuan; Ren, Leisheng; Liu, Sen

    2013-08-01

    Because of the large amount of debris in a debris cloud, it is hard to achieve a complete description of all the debris by a simple function. One workable approach is to use a group of complete distribution functions and MonteCarlo method to simplify the debris cloud simulation. Enough debris samples are produced by SPH simulation and debris identification program firstly. According to the distribution functions of debris mass, velocity and space angles determined by statistical analysis, the engineering model of debris cloud is set up. Combining the engineering model and MonteCarlo method, the fast simulation of debris cloud produced by an aluminum projectile impacting an aluminum plate is realized. An application example of the debris cloud engineering model to predict satellite damage caused by space debris impact is given at the end.

  1. Characterizing Secondary Debris Impact Ejecta

    NASA Technical Reports Server (NTRS)

    Schonberg, W. P.

    1999-01-01

    All spacecraft in low-Earth orbit are subject to high-speed impacts by meteoroids and orbital debris particles. These impacts can damage flight-critical systems which can in turn lead to catastrophic failure of the spacecraft. Therefore, the design of a spacecraft for an Earth-orbiting mission must take into account the possibility of such impacts and their effects on the spacecraft structure and on all of its exposed subsystem components. In addition to threatening the operation of the spacecraft itself, on-orbit impacts also generate a significant amount of ricochet particles. These high-speed particles can destroy critical external spacecraft subsystem and also increase the contamination of the orbital environment. This report presents a summary of the work performed towards the development of an empirical model that characterizes the secondary ejecta created by a high-speed impacta on a typical aerospace structural surface.

  2. Space debris studies in Japan

    NASA Astrophysics Data System (ADS)

    Toda, Susumu; Yasaka, Tetsuo

    1993-08-01

    The Space Debris Study Group of the Japan Society for Aeronautical and Space Sciences was established in September 1990 and the Interim Report was published in January 1992. The group has five subgroups: Observation, Cause, Modeling, Protection, and Social Impact. It intends to promote an awareness for the problem and put together related researches, to define the urgently needed activity area by first describing the present situation in each engineering field and then summarizing on-going respective researches. It is expected that sound technological base line understandings to the problem are to be attained at various institutions. International cooperations are indispensable, and Japanese efforts should be focused on those which do not duplicate but are complementary to achievements in other countries. Some of the results obtained by the group are presented and several examples of individual researches are summarized.

  3. LDEF meteoroid and debris database

    NASA Technical Reports Server (NTRS)

    Dardano, C. B.; See, Thomas H.; Zolensky, Michael E.

    1994-01-01

    The Long Duration Exposure Facility (LDEF) Meteoroid and Debris Special Investigation Group (M&D SIG) database is maintained at the Johnson Space Center (JSC), Houston, Texas, and consists of five data tables containing information about individual features, digitized images of selected features, and LDEF hardware (i.e., approximately 950 samples) archived at JSC. About 4000 penetrations (greater than 300 micron in diameter) and craters (greater than 500 micron in diameter) were identified and photodocumented during the disassembly of LDEF at the Kennedy Space Center (KSC), while an additional 4500 or so have subsequently been characterized at JSC. The database also contains some data that have been submitted by various PI's, yet the amount of such data is extremely limited in its extent, and investigators are encouraged to submit any and all M&D-type data to JSC for inclusion within the M&D database. Digitized stereo-image pairs are available for approximately 4500 features through the database.

  4. Application of the Empirical Thresholds of Precipitation to the Debris Flows in Mexico

    NASA Astrophysics Data System (ADS)

    Cardoso-Landa, G.

    2013-05-01

    The debris flows are particularly dangerous for the life and the properties due to its high speeds and great destructive force, destroying houses, ways, bridges, trees and cultures, currents and ecosystems throughout its trajectory. The extraordinary precipitation events are one of the predominant physical processes that produce the genesis of the debris flows. The empirical thresholds of precipitation are based on the historical analyses of the occurrence relation precipitation/debris flow, for example statistical analyses. At the present time a limited number of this type of empirical thresholds exists and have been used different diagrams to represent them, depending on the combinations of precipitation parameters more commonly used: antecedent precipitation, duration, accumulated intensity and rain, and the most commons are that obtained by Caine and Aleotti. An analytical presentation of the concept of threshold of precipitation of a debris flow was recently introduced by Iritanno et al. (1998), who introduced the called function of mobilization Y(t), indirectly describing all the factors that contribute to trigger a process of landslides and that is dependent, in every moment of time t, the amount of water infiltrate on the ground before the time t. In the full article was applied the Iritanno's function of mobilization to the records of precipitation that produced the debris flows in the north of Puebla State, in the country of México, obtaining relationships intensity of rain-duration for these debris flows are greater from 3.43 to 2.1 times over empirical thresholds of precipitation generators of debris flows proposed by Caine and Aleotti in other regions of the world. .Intensity of precipitation for the debris flows in Mexicot;

  5. Probabilistic rainfall thresholds for triggering debris flows in a human-modified landscape

    NASA Astrophysics Data System (ADS)

    Giannecchini, Roberto; Galanti, Yuri; D'Amato Avanzi, Giacomo; Barsanti, Michele

    2016-03-01

    In the Carrara Marble Basin (CMB; Apuan Alps, Italy) quarrying has accumulated widespread and thick quarry waste, lying on steep slopes and invading valley bottoms. The Apuan Alps are one of the rainiest areas in Italy and rainstorms often cause landslides and debris flows. The stability conditions of quarry waste are difficult to assess, owing to its textural, geotechnical and hydrogeological variability. Therefore, empirical rainfall thresholds may be effective in forecasting the possible occurrence of debris flows in the CMB. Three types of thresholds were defined for three rain gauges of the CMB and for the whole area: rainfall intensity-rainfall duration (ID), cumulated event rainfall-rainfall duration (ED), and cumulated event rainfall normalized by the mean annual precipitation-rainfall intensity (EMAPI). The rainfall events recorded from 1950 to 2005 was analyzed and compared with the occurrence of debris flows involving the quarry waste. They were classified in events that triggered one or more debris flows and events that did not trigger debris flows. This dataset was fitted using the logistic regression method that allows us to define a set of thresholds, corresponding to different probabilities of failure (from 10% to 90%) and therefore to different warning levels. The performance of the logistic regression in defining probabilistic thresholds was evaluated by means of contingency tables, skill scores and receiver operating characteristic (ROC) analysis. These analyses indicate that the predictive capability of the three types of threshold is acceptable for each rain gauge and for the whole CMB. The best compromise between the number of correct debris flow predictions and the number of wrong predictions is obtained for the 40% probability thresholds. The results obtained can be tested in an experimental debris flows forecasting system based on rainfall thresholds, and could have implications for the debris flow hazard and risk assessment in the CMB.

  6. Simulation of Micron-Sized Debris Populations in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Xu, Yu-Lin; Matney, Mark; Liou, J.-C.; Hyde, James; Prior, Thomas G.

    The update of ORDEM2000, the NASA Orbital Debris Engineering Model, to its new version -ORDEM2010, is nearly complete. As a part of the ORDEM upgrade, this paper addresses the simulation of micro-debris (greater than 10 µm and smaller than 1 mm in size) populations in low Earth orbit. The principal data used in the modeling of the micron-sized debris popu-lations are in-situ hypervelocity impact records, accumulated in post-flight damage surveys on the space-exposed surfaces of returned spacecrafts. The development of the micro-debris model populations follows the general approach to deriving other ORDEM2010-required input popu-lations for various components and types of debris. This paper describes the key elements and major steps in the statistical inference of the ORDEM2010 micro-debris populations. A crucial step is the construction of a degradation/ejecta source model to provide prior information on the micron-sized objects (such as orbital and object-size distributions). Another critical step is to link model populations with data, which is rather involved. It demands detailed information on area-time/directionality for all the space-exposed elements of a shuttle orbiter and damage laws, which relate impact damage with the physical properties of a projectile and impact con-ditions such as impact angle and velocity. Also needed are model-predicted debris fluxes as a function of object size and impact velocity from all possible directions. In spite of the very limited quantity of the available shuttle impact data, the population-derivation process is satis-factorily stable. Final modeling results obtained from shuttle window and radiator impact data are reasonably convergent and consistent, especially for the debris populations with object-size thresholds at 10 and 100 µm.

  7. Simulation of Micron-Sized Debris Populations in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Hyde, J. L.; Prior, T.; Matney, Mark

    2010-01-01

    The update of ORDEM2000, the NASA Orbital Debris Engineering Model, to its new version ORDEM2010, is nearly complete. As a part of the ORDEM upgrade, this paper addresses the simulation of micro-debris (greater than 10 m and smaller than 1 mm in size) populations in low Earth orbit. The principal data used in the modeling of the micron-sized debris populations are in-situ hypervelocity impact records, accumulated in post-flight damage surveys on the space-exposed surfaces of returned spacecrafts. The development of the micro-debris model populations follows the general approach to deriving other ORDEM2010-required input populations for various components and types of debris. This paper describes the key elements and major steps in the statistical inference of the ORDEM2010 micro-debris populations. A crucial step is the construction of a degradation/ejecta source model to provide prior information on the micron-sized objects (such as orbital and object-size distributions). Another critical step is to link model populations with data, which is rather involved. It demands detailed information on area-time/directionality for all the space-exposed elements of a shuttle orbiter and damage laws, which relate impact damage with the physical properties of a projectile and impact conditions such as impact angle and velocity. Also needed are model-predicted debris fluxes as a function of object size and impact velocity from all possible directions. In spite of the very limited quantity of the available shuttle impact data, the population-derivation process is satisfactorily stable. Final modeling results obtained from shuttle window and radiator impact data are reasonably convergent and consistent, especially for the debris populations with object-size thresholds at 10 and 100 m.

  8. Simulation of Micron-Sized Debris Populations in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Hyde, J. L.; Prior, T.; Matney, Mark

    2010-01-01

    The update of ORDEM2000, the NASA Orbital Debris Engineering Model, to its new version ORDEM2010, is nearly complete. As a part of the ORDEM upgrade, this paper addresses the simulation of micro-debris (greater than 10 m and smaller than 1 mm in size) populations in low Earth orbit. The principal data used in the modeling of the micron-sized debris populations are in-situ hypervelocity impact records, accumulated in post-flight damage surveys on the space-exposed surfaces of returned spacecrafts. The development of the micro-debris model populations follows the general approach to deriving other ORDEM2010-required input populations for various components and types of debris. This paper describes the key elements and major steps in the statistical inference of the ORDEM2010 micro-debris populations. A crucial step is the construction of a degradation/ejecta source model to provide prior information on the micron-sized objects (such as orbital and object-size distributions). Another critical step is to link model populations with data, which is rather involved. It demands detailed information on area-time/directionality for all the space-exposed elements of a shuttle orbiter and damage laws, which relate impact damage with the physical properties of a projectile and impact conditions such as impact angle and velocity. Also needed are model-predicted debris fluxes as a function of object size and impact velocity from all possible directions. In spite of the very limited quantity of the available shuttle impact data, the population-derivation process is satisfactorily stable. Final modeling results obtained from shuttle window and radiator impact data are reasonably convergent and consistent, especially for the debris populations with object-size thresholds at 10 and 100 m.

  9. Simulation of Micron-Sized Debris Populations in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Matney, M.; Liou, J.-C.; Hyde, J. L.; Prior, T. G.

    2010-01-01

    The update of ORDEM2000, the NASA Orbital Debris Engineering Model, to its new version . ORDEM2010, is nearly complete. As a part of the ORDEM upgrade, this paper addresses the simulation of micro-debris (greater than 10 micron and smaller than 1 mm in size) populations in low Earth orbit. The principal data used in the modeling of the micron-sized debris populations are in-situ hypervelocity impact records, accumulated in post-flight damage surveys on the space-exposed surfaces of returned spacecrafts. The development of the micro-debris model populations follows the general approach to deriving other ORDEM2010-required input populations for various components and types of debris. This paper describes the key elements and major steps in the statistical inference of the ORDEM2010 micro-debris populations. A crucial step is the construction of a degradation/ejecta source model to provide prior information on the micron-sized objects (such as orbital and object-size distributions). Another critical step is to link model populations with data, which is rather involved. It demands detailed information on area-time/directionality for all the space-exposed elements of a shuttle orbiter and damage laws, which relate impact damage with the physical properties of a projectile and impact conditions such as impact angle and velocity. Also needed are model-predicted debris fluxes as a function of object size and impact velocity from all possible directions. In spite of the very limited quantity of the available shuttle impact data, the population-derivation process is satisfactorily stable. Final modeling results obtained from shuttle window and radiator impact data are reasonably convergent and consistent, especially for the debris populations with object-size thresholds at 10 and 100 micron.

  10. Frequency and magnitude of debris flows on Cheekye River, British Columbia

    NASA Astrophysics Data System (ADS)

    Jakob, M.; Friele, P.

    2010-01-01

    Natural hazard and risk assessments are predicated on a detailed understanding of the relationship between frequency and magnitude of the hazardous process under investigation. When information is sought from the deep past (i.e., several thousand years), continuous event records do not exist and the researcher has to rely on proxy data to develop the frequency-magnitude ( F- M) model. Such work is often prohibitively expensive and few well-researched examples for mass movement are available worldwide. The Cheekye fan is a desirable location for land development and has a depth and breadth of previous research unprecedented on any debris-flow fan in Canada. We pursued two principal strains of research to formulate a reliable F- M relationship. The first focuses on stratigraphic analyses combined with radiometric dating and dendrochronology to reconstruct a comprehensive picture of Holocene debris-flow activity. The second approach examines hydrological limitations of rock avalanche evolution into debris flows through either entrainment of saturated sediments or by failure of a landslide-generated dam and upstream impoundment. We thus hypothesize that debris flows from Cheekye River can be separated into two quasi-homogenous populations: those that are typically triggered by relatively small debris avalanches, slumps, or rock falls or simply by progressive bulking of in-stream erodible sediments; and those that are thought to result from transformation of rock avalanches. Our work suggests that debris flows exceeding some 3 million m 3 in volume are unlikely to reach the Cheekye fan as a result of limited water available to fully fluidize a rock avalanche. This analysis has also demonstrated that in order to arrive at reasonable estimates for the frequency and magnitude of debris flows on a complex alluvial fan significant multidisciplinary efforts are required. Without the significant precursor investigations and the additional efforts of this study, life and

  11. Final Design for a Comprehensive Orbital Debris Management Program

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The rationale and specifics for the design of a comprehensive program for the control of orbital debris, as well as details of the various components of the overall plan, are described. The problem of orbital debris has been steadily worsening since the first successful launch in 1957. The hazards posed by orbital debris suggest the need for a progressive plan for the prevention of future debris, as well as the reduction of the current debris level. The proposed debris management plan includes debris removal systems and preventative techniques and policies. The debris removal is directed at improving the current debris environment. Because of the variance in sizes of debris, a single system cannot reasonably remove all kinds of debris. An active removal system, which deliberately retrieves targeted debris from known orbits, was determined to be effective in the disposal of debris tracked directly from earth. However, no effective system is currently available to remove the untrackable debris. The debris program is intended to protect the orbital environment from future abuses. This portion of the plan involves various environment from future abuses. This portion of the plan involves various methods and rules for future prevention of debris. The preventative techniques are protective methods that can be used in future design of payloads. The prevention policies are rules which should be employed to force the prevention of orbital debris.

  12. Weathering rinds on clasts: Examples from Earth and Mars as short and long term recorders of paleoenvironment

    NASA Astrophysics Data System (ADS)

    Mahaney, W. C.; Fairén, Alberto G.; Dohm, James M.; Krinsley, D. H.

    2012-12-01

    Weathering rinds on clasts of different lithologic species are an underappreciated inventory of paleoenvironmental information and, as recorders of long term exposure to the subaerial atmosphere and in some cases to burial and influx of groundwater followed by exhumation, they provide logged information over varying planetary time spans. Whereas weathered coatings of nanometer thickness have been explored by numerous workers, rinds in cold environments have not received much attention except as relative-age indicators. Rinds in terrestrial materials in certain circumstances may reveal weathering trends over time, snapshots often extending back millions of years and containing weathering zones not unlike horizons in paleosols. Wetting ‘fronts’ in rinds on coarse clastic debris (i.e. boulder, cobble, and pebble grade size material) are similar to wetting ‘depths’ in similar chemically-energized paleosols resident in moraines or mass wasted debris. Even considering erosion along terrestrial clast surfaces, new data reveal variations in primary mineral alteration, development of secondary mineral complexes, embedded pollen, fossil microbes, and various internal distributions of Fe oxides. Similar long-range recorders of paleoenvironment deduced from meteorites analyzed by the Opportunity rover on Meridiani Planum provide evidence of weathering over a ∼Gy time frame in the humid Noachian paleoenvironment of Early Mars followed by subsequent burial and later exhumation. Despite lithological variations between different sets of clasts-terrestrial and Martian-the retention of rinds as paleoweathering recorders over long and short time frames illustrates their value in paleoenvironmental reconstruction.

  13. Late Holocene Marine Sediment Record from the Bransfield Basin, Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Barnard, A.; Wellner, J. S.

    2009-12-01

    A comparison of published records of marine sediment cores from fjords around the northern Antarctic Peninsula suggests that climate change during the deglacial period occurred diachronously across the region. This is in contrast to the widespread retreat observed today. However, detailed records of the Holocene climate from the Antarctic Peninsula are widely spaced and this paucity does not allow for an understanding of the controls on the changes in different areas, or if the apparent diachronous change is simply due to poor chronostratigraphic controls. The purpose of this study is to correlate studies that are separated by large distances with a new record in a central location. The Bransfield Basin is located between the Antarctic Peninsula and the South Shetland Islands and links marine records from the Firth of Tay, Maxwell Bay, Palmer Deep and the western Bransfield Basin. This study focuses on a 22 m sediment core collected in 2007 from the deep central Bransfield Basin, which spans the last 4000 years. Analyses completed to date include core descriptions, laser particle size analysis, multi-sensor core logger analysis, X-ray radiograph fabric description, pebble count and petrography. Ongoing analyses include TOC, total C, total N, 12-13C and 14-15N. The core lithology is dominantly characterized by diatomaceous mud with varying amounts of terrigenous sediment and ice rafted debris. Interpretation of the sedimentary facies suggests that this is a high-resolution record of climatic change that may be used to link other records in this region.

  14. Optical scattering (TAOS) by tire debris particles: preliminary results

    NASA Astrophysics Data System (ADS)

    Crosta, Giovanni F.; Camatini, Marina C.; Zomer, Simeone; Holler, Stephen; Pan, Yongle; Bhaskara, Praveena; Muangchareon, Pongphisanu; Sung, Changmo; Cencetti, Simone; Regazzoni, Claudia

    2001-03-01

    Tire debris particles from low severity laboratory wear tests have been investigated by the TAOS optical scattering facility at Yale University. The incident wavelength is 532 nm. After the TAOS event some particle samples have been imaged by a scanning electron microscope and microanalyzed. The TAOS intensity patterns recorded within a solid angle in the backward sector have been processed by cluster analysis and compared with the patterns computed by a T-matrix code. Preliminary agreement has been found between TAOS data and the particle models (size, shape, refractive index). The purpose of the investigation is to obtain signatures of the material, based on its TAOS pattern.

  15. Optical scattering (TAOS) by tire debris particles: preliminary results.

    PubMed

    Crosta, G; Camatini, M; Zomer, S; Holler, S; Pan, Y; Bhaskara, P; Muangchareon, P; Sung, C; Cencetti, S; Regazzoni, C

    2001-03-12

    Tire debris particles from low severity laboratory wear tests have been investigated by the TAOS optical scattering facility at Yale University. The incident wavelength is 532 nm. After the TAOS event some particle samples have been imaged by a scanning electron microscope and microanalyzed. The TAOS intensity patterns recorded within a solid angle in the backward sector have been processed by cluster analysis and compared with the patterns computed by a T-matrix code. Preliminary agreement has been found between TAOS data and the particle models (size, shape, refractive index). The purpose of the investigation is to obtain signatures of the material, based on its TAOS pattern.

  16. Orbital debris removal and meteoroid deflection

    NASA Astrophysics Data System (ADS)

    Campbell, Jonathan W.; Taylor, Charles R.; Smalley, Larry L.; Dickerson, Thomas

    1998-11-01

    Orbital debris in low-Earth orbit in the size range from 1 to 10 cm in diameter can be detected but not tracked reliably enough to be avoided by spacecraft. It can cause catastrophic damage even to a shielded spacecraft. With adaptive optics, a ground-based pulsed laser ablating the debris surface can produce enough propulsion in several hundred pulses to cause such debris to reenter the atmosphere. A single laser station could remove all of the 1 - 10 cm debris in three years or less. A technology demonstration of laser space propulsion is proposed which would pave the way for the implementation of such a debris removal system. The cost of the proposed demonstration is comparable with the estimated annual cost of spacecraft operations in the present orbital debris environment. Orbital debris is not the only space junk that is deleterious to the Earth's environment. Collisions with asteroids have caused major havoc to the Earth's biosphere many times in the ancient past. Since the possibility still exists for major impacts of asteroids with the Earth, it shown that it is possible to scale up the systems to prevent these catastrophic collisions providing sufficient early warning is available from new generation space telescopes plus deep space radar tracking.

  17. The ESA Space Debris Mitigation Handbook 2002

    NASA Astrophysics Data System (ADS)

    Klinkrad, H.; Beltrami, P.; Hauptmann, S.; Martin, C.; Sdunnus, H.; Stokes, H.; Walker, R.; Wilkinson, J.

    2004-01-01

    The ESA Space Debris Mitigation Handbook 2002 was jointly produced by an industrial consortium and ESA, under an ESA contract. The Handbook is a non-regulatory, self-standing document, providing technical information in support of European debris mitigation standards. The necessity of debris mitigation is illustrated in the context of historic launch activities and operational practices, which led to the current debris environment, with corresponding collision flux levels. Based on detailed population evolution models, this initial population is analyzed with respect to its growth and stability under different traffic assumptions. The implementation of debris mitigation measures, in particular the de-orbiting of spacecraft and upper stages, is shown to reduce the debris growth to an acceptable level within a few decades. The risk on ground due to re-entering space objects, its assessment, and its control is also analyzed. For on-orbit systems, collision risk reduction by avoidance manoeuvres, and passive protection by shielding is outlined. ESA's Handbook also compares recommended debris mitigation and risk reduction practices proposed by several other space agencies. The Handbook will be available at the begin of 2003.

  18. The ESA Space Debris Mitigation Handbook 2002

    NASA Astrophysics Data System (ADS)

    Klinkrad, H.; Beltrami, P.; Hauptmann, S.; Martin, C.; Sdunnus, H.; Stokes, H.; Walker, R.; Wilkinson, J.

    The ESA Space Debris Mitigation Handbook 2002 was jointly produced by an industrial consortium and ESA, under an ESA contract. The Handbook is a non-regulatory, self-standing document, providing technical information in support of European debris mitigation standards. The necessity of debris mitigation is illustrated in the context of historic launch activities and operational practices, which led to the current debris environment, with corresponding collision flux levels. Based on detailed population evolution models, this initial population is analysed with respect to its growth and stability under different traffic assumptions. The implementation of debris mitigation measures, in particular the de-orbiting of spacecraft and upper stages, is shown to reduce the debris growth to an acceptable level within a few decades. The risk on ground due to re-entering space objects, its assessment, and its control is also analysed. For on-orbit systems, collision risk reduction by avoidance manoeuvres, and passive protection by shielding is outlined. ESA's Handbook also compares recommended debris mitigation and risk reduction practices proposed by several other space agencies. The Handbook will be available by the end of 2002.

  19. Nuclear-powered space debris sweeper

    NASA Technical Reports Server (NTRS)

    Metzger, John D.; Leclaire, Rene J., Jr.; Howe, Steven D.; Burgin, Karen C.

    1989-01-01

    Future spacecraft design will be affected by collisions with man-made debris orbiting the earth. Most of this orbital space debris comes from spent rocket stages. It is projected that the source of future debris will be the result of fragmentation of large objects through hypervelocity collisions. Orbiting spacecraft will have to be protected from hypervelocity debris in orbit. The options are to armor the spacecraft, resulting in increased mass, or actively removing the debris from orbit. An active space debris sweeper is described which will utilize momentum transfer to the debris through laser-induced ablation to alter its orbital parameters to reduce orbital lifetime with eventual entry into the earth's atmosphere where it will burn. The paper describes the concept, estimates the amount of velocity change (Delta V) that can be imparted to an object through laser-induced ablation, and investigates the use of a neutral particle beam for the momentum transfer. The space sweeper concept could also be extended to provide a collision avoidance system for the space station and satellites, or could be used for collision protection during interplanetary travel.

  20. Quantitative reconstruction of late Holocene surface evolution on an alpine debris-flow fan

    NASA Astrophysics Data System (ADS)

    Schürch, Peter; Densmore, Alexander L.; Ivy-Ochs, Susan; Rosser, Nick J.; Kober, Florian; Schlunegger, Fritz; McArdell, Brian; Alfimov, Vasili

    2016-12-01

    Debris-flow fans form a ubiquitous record of past debris-flow activity in mountainous areas, and may be useful for inferring past flow characteristics and consequent future hazard. Extracting information on past debris flows from fan records, however, requires an understanding of debris-flow deposition and fan surface evolution; field-scale studies of these processes have been very limited. In this paper, we document the patterns and timing of debris-flow deposition on the surface of the large and exceptionally active Illgraben fan in southwestern Switzerland. We use terrain analysis, radiocarbon dating of sediment fill in the Illgraben catchment, and cosmogenic 10Be and 36Cl exposure dating of debris-flow deposits on the fan to constrain the temporal evolution of the sediment routing system in the catchment and on the fan during the past 3200 years. We show that the fan surface preserves a set of debris-flow lobes that were predominantly deposited after the occurrence of a large rock avalanche near the fan apex at about 3200 years ago. This rock avalanche shifted the apex of the fan and impounded sediment within the Illgraben catchment. Subsequent evolution of the fan surface has been governed by both lateral and radial shifts in the active depositional lobe, revealed by the cosmogenic radionuclide dates and by cross-cutting geometrical relationships on the fan surface. This pattern of frequent avulsion and fan surface occupation provides field-scale evidence of the type of large-scale compensatory behavior observed in experimental sediment routing systems.

  1. Boundary Spanning Leadership Practices for Population Health.

    PubMed

    Shirey, Maria R; White-Williams, Connie

    2015-09-01

    This department highlights change management strategies that may be successful in strategically planning and executing organizational change initiatives. In this article, the authors discuss boundary spanning leadership practices for achieving the Triple Aim of simultaneously improving the health of populations, improving the patient experience, and reducing per-capita cost of health care. Drawing on experience with an existing population-focused heart failure clinic borne of an academic-practice partnership, the authors discuss boundary spanning leadership practices aimed at achieving the Triple Aim concept and its intended design.

  2. Orbital Debris and NASA's Measurement Program

    NASA Astrophysics Data System (ADS)

    Africano, J. L.; Stansbery, E. G.

    2002-05-01

    Since the launch of Sputnik in 1957, the number of manmade objects in orbit around the Earth has dramatically increased. The United States Space Surveillance Network (SSN) tracks and maintains orbits on over nine thousand objects down to a limiting diameter of about ten centimeters. Unfortunately, active spacecraft are only a small percentage ( ~ 7%) of this population. The rest of the population is orbital debris or ``space junk" consisting of expended rocket bodies, dead payloads, bits and pieces from satellite launches, and fragments from satellite breakups. The number of these smaller orbital debris objects increases rapidly with decreasing size. It is estimated that there are at least 130,000 orbital debris objects between one and ten centimeters in diameter. Most objects smaller than 10 centimeters go untracked! As the orbital debris population grows, the risk to other orbiting objects, most importantly manned space vehicles, of a collision with a piece of debris also grows. The kinetic energy of a solid 1 cm aluminum sphere traveling at an orbital velocity of 10 km/sec is equivalent to a 400 lb. safe traveling at 60 mph. Fortunately, the volume of space in which the orbiting population resides is large, collisions are infrequent, but they do occur. The Space Shuttle often returns to earth with its windshield pocked with small pits or craters caused by collisions with very small, sub-millimeter-size pieces of debris (paint flakes, particles from solid rocket exhaust, etc.), and micrometeoroids. To get a more complete picture of the orbital-debris environment, NASA has been using both radar and optical techniques to monitor the orbital debris environment. This paper gives an overview of the orbital debris environment and NASA's measurement program.

  3. POST Earthquake Debris Management - AN Overview

    NASA Astrophysics Data System (ADS)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  4. POST Earthquake Debris Management — AN Overview

    NASA Astrophysics Data System (ADS)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  5. How marine debris ingestion differs among megafauna species in a tropical coastal area.

    PubMed

    Di Beneditto, Ana Paula Madeira; Awabdi, Danielle Rodrigues

    2014-11-15

    The marine debris ingested by megafauna species (Trichiurus lepturus, Chelonia mydas, Pontoporia blainvillei, and Sotalia guianensis) was recorded in a coastal area of southeastern Brazil (21-23°S). Marine debris was recorded in all species, mainly consisting of plastic material (flexible and hard plastics - clear, white, and colored- and nylon filaments). The 'pelagic predators' T. lepturus and S. guianesis showed the lowest percent frequencies of debris ingestion (0.7% and 1.3%, respectively), followed by the 'benthic predator' P. blainvillei (15.7%) and the 'benthic herbivorous C. mydas (59.2%). The debris found in C. mydas stomachs was opportunistically ingested during feeding activities on local macroalgal banks. In the study area, the benthic environment accumulates more anthropogenic debris than the pelagic environment, and benthic/demersal feeders are more susceptible to encounters and ingestion. The sub-lethal effects observed in C. mydas, such as intestinal obstruction due to hardened fecal material, should be considered a local conservation concern. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Debris in the deep: Using a 22-year video annotation database to survey marine litter in Monterey Canyon, central California, USA

    NASA Astrophysics Data System (ADS)

    Schlining, Kyra; von Thun, Susan; Kuhnz, Linda; Schlining, Brian; Lundsten, Lonny; Jacobsen Stout, Nancy; Chaney, Lori; Connor, Judith

    2013-09-01

    Anthropogenic marine debris is an increasing concern because of its potential negative impacts on marine ecosystems. This is a global problem that will have lasting effects for many reasons, including: (1) the input of debris into marine environments is likely to continue (commensurate with population increase and globalization), (2) accumulation, and possibly retention, of debris will occur in specific areas due to hydrography and geomorphology, and (3) the most common types of debris observed to date will likely persist for centuries. Due to the technical challenges and prohibitive costs of conducting research in the deep sea, little is known about the abundance, types, sources, and impacts of human refuse on this vast habitat, and the extreme depths to which this debris is penetrating has only recently been exposed. We reviewed 1149 video records of marine debris from 22 years of remotely operated vehicle deployments in Monterey Bay, covering depths from 25 m to 3971 m. We characterize debris by type, examine patterns of distribution, and discuss potential sources and dispersal mechanisms. Debris was most abundant within Monterey Canyon where aggregation and downslope transport of debris from the continental shelf are enhanced by natural canyon dynamics. The majority of debris was plastic (33%) and metal (23%). The highest relative frequencies of plastic and metal observations occurred below 2000 m, indicating that previous studies may greatly underestimate the extent of anthropogenic marine debris on the seafloor due to limitations in observing deeper regions. Our findings provide evidence that submarine canyons function to collect debris and act as conduits for debris transport from coastal to deep-sea habitats.

  7. 23 | September | 201span>6 | ISS On-Orbit Status Report

    NASA Website

    Opening of Lab MCA Hand Valve 01; HRF2 Supply Kit Resupply; ... August 201span>6; July 201span>6; June 201span>6; May 201span>6; April 201span>6; March 201span>6; February 201span>6; ...

  8. Succession of desert plants on debris flow terraces, Grand Canyon, Arizona, U.S.A.

    USGS Publications Warehouse

    Bowers, Janice E.; Webb, R.H.; Pierson, E.A.

    1997-01-01

    Vegetation sampling on 11 debris flow terraces in Grand Canyon National Park, Arizona, U.S.A., showed that plant assemblages changed as age of surface increased. The terraces ranged in age from about 5 to about 3100 years. There were distinct differences among sites in the life history characteristics of the dominant plants. Young terraces (5-55 years) were dominated by short-lived plants that had high reproductive potential. Older surfaces were dominated by species with longer life-spans and lower reproductive potential. Density and cover of long-lived species increased with age of surface; for short-lived plants, density was inversely related to surface age. Species composition was also correlated with site age; however, location, exposure, and other factors ensured that no two debris flows supported identical mixtures of species. Succession on recent Grand Canyon debris flows is driven in part by life-history strategies, particularly life-span and seed dispersal traits, and also by climatic factors, especially those that control germination and establishment of the long-lived dominants.

  9. Collector/Compactor for Waste or Debris

    NASA Technical Reports Server (NTRS)

    Mangialiardi, John K.

    1987-01-01

    Device collects and compacts debris by sweeping through volume with net. Consists of movable vane, fixed vane, and elastic net connected to both vanes. Movable vane is metal strip curved to follow general contour of container with clearance to prevent interference with other parts on inside wall of container. One end of movable vane mounted in bearing and other end connected to driveshaft equipped with handle. User rotates movable vane, net stretched and swept through container. Captures most of debris coarser than mesh as it moves, compressing debris as it arrives at fixed vane. Applications include cleaning swimming pools and tanks.

  10. Modelling of space debris and meteoroids

    NASA Astrophysics Data System (ADS)

    Mandeville, J. C.; Alby, F.

    1997-05-01

    Since several years, CNES has undertaken studies in the field of debris and meteoroids since the knowledge of this environment is of prime importance for space activities and will be a growing concern in the future. In the frame of this study, the main available models concerning space debris and meteoroids have been analysed: origin, principle of modelization, limits and evolution as a function of time. A reference model has been choosen and evaluated through comparisons with available data, coming from in flight experiments such as LDEF, EURECA, MIR and HUBBLE. This work will lead in the future to improve the models, particularly for the small size debris.

  11. Space Shuttle crew compartment debris-contamination

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Villarreal, Leopoldo J.

    1992-01-01

    Remedial actions undertaken to reduce debris during manned flights and ground turnaround operations at Kennedy Space Center and Palmdale are addressed. They include redesign of selected ground support equipment and Orbiter hardware to reduce particularization/debris generation; development of new detachable filters for air-cooled avionics boxes; application of tape-on screens to filter debris; and implementation of new Orbiter maintenance and turnaround procedures to clean filters and the crew compartment. Most of these steps were implemented before the return-to-flight of STS-26 in September 1988 which resulted in improved crew compartment habitability and less potential for equipment malfunction.

  12. Algorithms for the Computation of Debris Risks

    NASA Technical Reports Server (NTRS)

    Matney, Mark

    2017-01-01

    Determining the risks from space debris involve a number of statistical calculations. These calculations inevitably involve assumptions about geometry - including the physical geometry of orbits and the geometry of non-spherical satellites. A number of tools have been developed in NASA's Orbital Debris Program Office to handle these calculations; many of which have never been published before. These include algorithms that are used in NASA's Orbital Debris Engineering Model ORDEM 3.0, as well as other tools useful for computing orbital collision rates and ground casualty risks. This paper will present an introduction to these algorithms and the assumptions upon which they are based.

  13. Algorithms for the Computation of Debris Risk

    NASA Technical Reports Server (NTRS)

    Matney, Mark J.

    2017-01-01

    Determining the risks from space debris involve a number of statistical calculations. These calculations inevitably involve assumptions about geometry - including the physical geometry of orbits and the geometry of satellites. A number of tools have been developed in NASA’s Orbital Debris Program Office to handle these calculations; many of which have never been published before. These include algorithms that are used in NASA’s Orbital Debris Engineering Model ORDEM 3.0, as well as other tools useful for computing orbital collision rates and ground casualty risks. This paper presents an introduction to these algorithms and the assumptions upon which they are based.

  14. Collector/Compactor for Waste or Debris

    NASA Technical Reports Server (NTRS)

    Mangialiardi, John K.

    1987-01-01

    Device collects and compacts debris by sweeping through volume with net. Consists of movable vane, fixed vane, and elastic net connected to both vanes. Movable vane is metal strip curved to follow general contour of container with clearance to prevent interference with other parts on inside wall of container. One end of movable vane mounted in bearing and other end connected to driveshaft equipped with handle. User rotates movable vane, net stretched and swept through container. Captures most of debris coarser than mesh as it moves, compressing debris as it arrives at fixed vane. Applications include cleaning swimming pools and tanks.

  15. Apparatus for controlling nuclear core debris

    DOEpatents

    Jones, Robert D.

    1978-01-01

    Nuclear reactor apparatus for containing, cooling, and dispersing reactor debris assumed to flow from the core area in the unlikely event of an accident causing core meltdown. The apparatus includes a plurality of horizontally disposed vertically spaced plates, having depressions to contain debris in controlled amounts, and a plurality of holes therein which provide natural circulation cooling and a path for debris to continue flowing downward to the plate beneath. The uppermost plates may also include generally vertical sections which form annular-like flow areas which assist the natural circulation cooling.

  16. 8. VIEW OF SUPERSTRUCTURE OF MOVABLE SPAN TRUSS WORK AND ...

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

    8. VIEW OF SUPERSTRUCTURE OF MOVABLE SPAN TRUSS WORK AND ROADWAY OF MOVABLE SPAN, LOOKING NORTH (taken in December 1983) - Sharptown Bridge, Spanning Nanticoke River, State Route 313, Sharptown, Wicomico County, MD

  17. 41. Detail showing meeting of two fixed land span segments, ...

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

    41. Detail showing meeting of two fixed land span segments, bridge land span at left, viaduct at right. VIEW NORTH - Broadway Bridge, Spanning Foundry Street, MBTA Yard, Fort Point Channel, & Lehigh Street, Boston, Suffolk County, MA

  18. 347. Caltrans, Photographer April 10, 1935 "500 FT. SPANS"; VIEW ...

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

    347. Caltrans, Photographer April 10, 1935 "500 FT. SPANS"; VIEW OF THROUGH TRUSS (500 FT. SPANS) UNDER CONSTRUCTION. 7-613 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  19. 26. Central compression lock, north span facing north. Compression lock ...

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

    26. Central compression lock, north span facing north. Compression lock locks two spans together at highest point. There are three compression locks. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  20. 5. LOOKING SOUTHEAST, VIEW OF CENTER TURN SPAN AND SOUTHWESTERNMOST ...

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

    5. LOOKING SOUTHEAST, VIEW OF CENTER TURN SPAN AND SOUTHWESTERNMOST SPAN FROM ADJACENT INTERSTATE 40 BRIDGE - St. Francis River Bridge, Spanning St. Francis River at U.S. Highway 70, Forrest City, St. Francis County, AR

  1. 3. GENERAL ELEVATION, FROM THE NORTH, SHOWING ENTIRE BASCULE SPAN ...

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

    3. GENERAL ELEVATION, FROM THE NORTH, SHOWING ENTIRE BASCULE SPAN AND FOCUSING ON FIXED SPAN IN FOREGROUND - Seddon Island Scherzer Rolling Lift Bridge, Spanning Garrison Channel from Tampa to Seddon Island, Tampa, Hillsborough County, FL

  2. 10. DETAIL, SOUTHEAST SPAN THROUGH CANAL, VIEW BLOCKED BY STEEL, ...

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

    10. DETAIL, SOUTHEAST SPAN THROUGH CANAL, VIEW BLOCKED BY STEEL, CLAD COUNTER WEIGHT, WATER SPAN RAISED OUT OF VIEW - Cape Cod Canal Lift Bridge, Spanning Cape Cod Canal, Buzzards Bay, Barnstable County, MA

  3. 13. VIEW TO WEST. DETAIL, WEST PIER, WEST APPROACH SPAN, ...

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

    13. VIEW TO WEST. DETAIL, WEST PIER, WEST APPROACH SPAN, LOCKING GEAR AT WEST END OF SWING SPAN. (photographed from boat) - Gianella Bridge, Spanning Sacramento River at State Highway 32, Hamilton City, Glenn County, CA

  4. 20. Detail view of west swing span abutment through swing ...

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

    20. Detail view of west swing span abutment through swing span truss, looking north - India Point Railroad Bridge, Spanning Seekonk River between Providence & East Providence, Providence, Providence County, RI

  5. 20. DETAIL OF WEST ANCHOR SPAN, CANTILEVER ARMS AND WEST ...

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

    20. DETAIL OF WEST ANCHOR SPAN, CANTILEVER ARMS AND WEST HALF OF SUSPENDED SPAN OF THROUGH TRUSS. VIEW TO NORTHEAST. - MacArthur Bridge, Spanning Mississippi River on Highway 34 between IA & IL, Burlington, Des Moines County, IA

  6. Estimates of downed woody debris decay class transitions for forests across the eastern United States

    Treesearch

    Matthew B. Russell; Christopher W. Woodall; Shawn Fraver; Anthony W. D' Amato

    2013-01-01

    Large-scale inventories of downed woody debris (DWD; downed dead wood of a minimum size) often record decay status by assigning pieces to classes of decay according to their visual/structural attributes (e.g., presence of branches, log shape, and texture and color of wood). DWD decay classes are not only essential for estimating current DWD biomass and carbon stocks,...

  7. General closeup view of the swing span bridge in the ...

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

    General close-up view of the swing span bridge in the close position, looking upriver. The pivot/center pier is positioned in the center of Tennessee River. Note: Each arm of the continuous swing span acts as simple spans. The total span over four (4) supports is partially continuous-- the middle panel at the center pier is continuous for bending moments, but discontinuous for shears. - Bridgeport Swing Span Bridge, Spanning Tennessee River, Bridgeport, Jackson County, AL

  8. Full Scale Span Load Distribution on a Tapered Wing with Split Flaps of Various Spans

    NASA Technical Reports Server (NTRS)

    Parsons, John F; Silverstein, Abe

    1937-01-01

    Pressure-distribution tests were conducted in the full-scale wind tunnel on a 2:1 tapered U.S.A. 45 airfoil equipped with 20 percent chord split trailing-edge flaps of various spans. A special installation was employed in the tests utilizing a half-span airfoil mounted vertically above a reflection plane. The airfoil has a constant chord center section and rounded tips and is tapered in thickness from 18 percent c at the root to 9 percent c at the tip. The aerodynamic characteristics, given by the usual dimension less coefficients, are presented graphically as functions of flap span and angle of attack as well as by semispan load diagrams. The results indicate, in general, that only a relatively small increase in the normal-force coefficient is to be expected by extending the flap span of an airfoil-flap combination, similar to the one tested, beyond 70 percent of the wing span.

  9. Sedimentology, Behavior, and Hazards of Debris Flows at Mount Rainier, Washington

    USGS Publications Warehouse

    Scott, K.M.; Vallance, J.W.; Pringle, P.T.

    1995-01-01

    middle segments of flow waves that begin and end as flood surges. Proximally, through the bulking of poorly sorted volcaniclastic debris on the flanks of the volcano, flow waves expand rapidly in volume by transforming from water surges through hyperconcentrated stream flow (20 to 60 percent sediment by volume) to debris flow. Distally, the transformations occur more slowly in reverse order - from debris flow, to hyperconcentrated flow, and finally to normal streamflow with less than 20 percent sediment by volume. During runout of the largest noncohesive flows, hyperconcentrated flow has continued for as much as 40 to 70 kilometers. Lahars (volcanic debris flows and their deposits) have occurred frequently at Mount Rainier over the past several thousand years, and generally they have not clustered within discrete eruptive periods as at Mount St. Helens. An exception is a period of large noncohesive flows during and after construction of the modern summit cone. Deposits from lahar-runout flows, the hyperconcentrated distal phases of lahars, document the frequency and extent of noncohesive lahars. These deposits also record the following transformations of debris flows: (1) the direct, progressive dilution of debris flow to hyperconcentrated flow, (2) deposition of successively finer grained lobes of debris until only the hyperconcentrated tail of the flow remains to continue downstream, and (3) dewatering of coarse debris flow deposits to yield fine-grained debris flow or hyperconcentrated flow. Three planning or design case histories represent different lengths of postglacial time. Case I is representative of large, infrequent (500 to 1,000 years on average) cohesive debris flows. These flows need to be considered in long-term planning in valleys around the volcano. Case II generalizes the noncohesive debris flows of intermediate size and recurrence (100 to 500 years). This case is appropriate for consideration in some structural design. Case III flows are

  10. Objective definition of rainfall intensity-duration thresholds for the initiation of post-fire debris flows in southern California

    USGS Publications Warehouse

    Staley, Dennis; Kean, Jason W.; Cannon, Susan H.; Schmidt, Kevin M.; Laber, Jayme L.

    2012-01-01

    Rainfall intensity–duration (ID) thresholds are commonly used to predict the temporal occurrence of debris flows and shallow landslides. Typically, thresholds are subjectively defined as the upper limit of peak rainstorm intensities that do not produce debris flows and landslides, or as the lower limit of peak rainstorm intensities that initiate debris flows and landslides. In addition, peak rainstorm intensities are often used to define thresholds, as data regarding the precise timing of debris flows and associated rainfall intensities are usually not available, and rainfall characteristics are often estimated from distant gauging locations. Here, we attempt to improve the performance of existing threshold-based predictions of post-fire debris-flow occurrence by utilizing data on the precise timing of debris flows relative to rainfall intensity, and develop an objective method to define the threshold intensities. We objectively defined the thresholds by maximizing the number of correct predictions of debris flow occurrence while minimizing the rate of both Type I (false positive) and Type II (false negative) errors. We identified that (1) there were statistically significant differences between peak storm and triggering intensities, (2) the objectively defined threshold model presents a better balance between predictive success, false alarms and failed alarms than previous subjectively defined thresholds, (3) thresholds based on measurements of rainfall intensity over shorter duration (≤60 min) are better predictors of post-fire debris-flow initiation than longer duration thresholds, and (4) the objectively defined thresholds were exceeded prior to the recorded time of debris flow at frequencies similar to or better than subjective thresholds. Our findings highlight the need to better constrain the timing and processes of initiation of landslides and debris flows for future threshold studies. In addition, the methods used to define rainfall thresholds in this

  11. Spatial Abilities across the Adult Life Span

    ERIC Educational Resources Information Center

    Borella, Erika; Meneghetti, Chiara; Ronconi, Lucia; De Beni, Rossana

    2014-01-01

    The study investigates age-related effects across the adult life span on spatial abilities (testing subabilities based on a distinction between spatial visualization, mental rotation, and perspective taking) and spatial self-assessments. The sample consisted of 454 participants (223 women and 231 men) from 20 to 91 years of age. Results showed…

  12. Spatial Abilities across the Adult Life Span

    ERIC Educational Resources Information Center

    Borella, Erika; Meneghetti, Chiara; Ronconi, Lucia; De Beni, Rossana

    2014-01-01

    The study investigates age-related effects across the adult life span on spatial abilities (testing subabilities based on a distinction between spatial visualization, mental rotation, and perspective taking) and spatial self-assessments. The sample consisted of 454 participants (223 women and 231 men) from 20 to 91 years of age. Results showed…

  13. Sensorimotor Synchronization across the Life Span

    ERIC Educational Resources Information Center

    Drewing, Knut; Aschersleben, Gisa; Li, Shu-Chen

    2006-01-01

    The present study investigates the contribution of general processing resources as well as other more specific factors to the life-span development of sensorimotor synchronization and its component processes. Within a synchronization tapping paradigm, a group of 286 participants, 6 to 88 years of age, were asked to synchronize finger taps with…

  14. Complex Systems: Boundary-Spanning Training Techniques.

    ERIC Educational Resources Information Center

    Adler, Terry; Black, Janice A.; Loveland, John P.

    2003-01-01

    The complex system dynamics of organizations and the influence of information technology requires workers to have boundary-spanning skills and the ability to work in virtual teams. The integrated business core is an experiential graduate-level course designed to develop these skills; it is also adaptable for inservice training. (Contains 69…

  15. School Organization: Grade Span. Trends and Issues.

    ERIC Educational Resources Information Center

    Renchler, Ron

    This paper examines grade spans (grade configurations) and their importance in community school systems. Research has shown that geographic location often dictates the kind of grade configuration districts use. Furthermore, every grade configuration has strengths and weaknesses, and school officials must focus on developing the positive potential…

  16. SPAN C - Terminal sterilization process analysis program

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Computer program, SPAN-C, measures the dry heat thermal sterilization process applied to a planetary capsule and calculates the time required for heat application, steady state conditions, and cooling. The program is based on the logarithmic survival of micro-organisms. Temperature profiles must be input on cards.

  17. SPAN - Terminal sterilization process analysis program

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Computer program, SPAN, measures the dry heat thermal sterilization process applied to a planetary capsule and calculates the time required for heat application, steady state conditions, and cooling. The program is based on the logarithmic survival of micro-organisms. Temperature profiles must be input on tape.

  18. Mantle Debris in Giant Impacts: Parameter-Space Study and Scaling Laws

    NASA Astrophysics Data System (ADS)

    Gabriel, Travis; Reufer, Andreas; Jackson, Alan P.; Asphaug, Erik

    2016-10-01

    Collisions between similar-sized planetesimals are prevalent throughout the early stages of the formation of the Solar System. N-body dynamics simulations commonly employed to understand planetary evolution depend on parameterized disruption/accretion criteria in order to consider the diversity of outcomes of these collisions. Additionally, understanding the debris from collisions is essential in tracing the source regions of volatiles, placing constraints on collisional grinding, and explaining the formation of small solar system bodies. We describe the transport of mantle material through debris production in giant impacts using a large database of SPH hydrocode simulations. We then develop new scaling laws that accurately capture the production of diverse debris products found in giant impacts with a range of relative velocities up to a few times the mutual escape velocity and a complete range of impact geometries. At typical impact angles it is found that giant impacts are significantly less erosive than suggested by existing scaling laws. This discrepancy grows with impact velocity and the impactor-to-target mass ratio, and thus it grows with the kinetic energy of the system. Our database spans a wide parameter space of pre-impact initial conditions, and includes chondritic and icy, chondritic material representative of the bulk abundances in the inner and outer solar system respectively. Implications for this new understanding in debris production through giant impacts are discussed.

  19. Evolution of the Debris Cloud Generated by the Fengyun-1C Fragmentation Event

    NASA Technical Reports Server (NTRS)

    Pardini, Carmen; Anselmo, Luciano

    2007-01-01

    The cloud of cataloged debris produced in low earth orbit by the fragmentation of the Fengyun-1C spacecraft was propagated for 15 years, taking into account all relevant perturbations. Unfortunately, the cloud resulted to be very stable, not suffering substantial debris decay during the time span considered. The only significant short term evolution was the differential spreading of the orbital planes of the fragments, leading to the formation of a debris shell around the earth approximately 7-8 months after the breakup, and the perigee precession of the elliptical orbits. Both effects will render the shell more "isotropic" in the coming years. The immediate consequence of the Chinese anti-satellite test, carried out in an orbital regime populated by many important operational satellites, was to increase significantly the probability of collision with man-made debris. For the two Italian spacecraft launched in the first half of 2007, the collision probability with cataloged objects increased by 12% for AGILE, in equatorial orbit, and by 38% for COSMO-SkyMed 1, in sun-synchronous orbit.

  20. 25. DETAIL VIEW OF COMMEMORATIVE NAMEPLATE PLAQUE, NORTH END SPAN ...

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

    25. DETAIL VIEW OF COMMEMORATIVE NAMEPLATE PLAQUE, NORTH END SPAN - East Bloomsburg Bridge, Spanning Susquehanna River at Pennsylvania Route 487 (Legislative Route 283), Bloomsburg, Columbia County, PA

  1. Perspective view of span over French Creek and east abutment, ...

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

    Perspective view of span over French Creek and east abutment, looking NW. - Pennsylvania Railroad, French Creek Trestle, Spanning French Creek, north of Paradise Street, Phoenixville, Chester County, PA

  2. 22. Detail view of approach span, showing bottom chord construction, ...

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

    22. Detail view of approach span, showing bottom chord construction, looking east - India Point Railroad Bridge, Spanning Seekonk River between Providence & East Providence, Providence, Providence County, RI

  3. 13. View of swing span showing bridge operator's control cabin, ...

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

    13. View of swing span showing bridge operator's control cabin, looking northeast - India Point Railroad Bridge, Spanning Seekonk River between Providence & East Providence, Providence, Providence County, RI

  4. Cross-stratified Wood: Enigmatic Woody Debris Deposits in Warm-Polar Fluvial Sediments (Pliocene Beaufort Formation, Nunavut)

    NASA Astrophysics Data System (ADS)

    Davies, N. S.; Gosse, J. C.; Rybczynski, N.

    2012-04-01

    Woody debris has been an important sediment component and a significant geomorphic agent in pristine fluvial systems since the Devonian. In recent years a large volume of research has focussed on various aspects of the importance of woody debris within the fluvial realm; from the evolutionary significance of fossil wood accumulations in the rock record to studies of the biogeomorphological and ecological importance of woody debris in modern rivers. In this presentation we describe cross-stratified woody debris deposits comprising organic detritus from a boreal-type treeline forest that included species of pine, birch, poplar, alder, spruce, eastern cedar, and larch, in both shrub and tree form. The cross-stratified wood is an enigmatic subset of fine woody debris which, to our knowledge, has never before been described from either the global stratigraphic record or modern fluvial environments. The deposits we describe are located within the Pliocene Beaufort Formation on Meighen Island, Nunavut, Canada, at a latitude of 80°N, and are compared with other cross-stratified woody debris deposits that have been noted elsewhere in the Pliocene of the Canadian Arctic. We make the robust observation that these deposits appear to be geographically and stratigraphically restricted to polar latitudes from a period of warm climatic conditions during the Pliocene (15-20 °C warmer mean annual temperature than the present day). In this regard it is possible to speculate that the transport of large amounts of woody debris as bedload is potentially a unique feature of forested high latitude rivers. Such bedload deposition requires a large amount of woody debris with a greater density than the fluid transporting it. The softwood composition of the debris suggests that this was most likely attained by saturation and subsequent entrainment of extensive accumulations of deadwood, promoted by unusually high rates of tree mortality and low rates of bacterial decomposition arising from

  5. Debris Examination Using Ballistic and Radar Integrated Software

    NASA Technical Reports Server (NTRS)

    Griffith, Anthony; Schottel, Matthew; Lee, David; Scully, Robert; Hamilton, Joseph; Kent, Brian; Thomas, Christopher; Benson, Jonathan; Branch, Eric; Hardman, Paul; Stuble, Martin

    2012-01-01

    The Debris Examination Using Ballistic and Radar Integrated Software (DEBRIS) program was developed to provide rapid and accurate analysis of debris observed by the NASA Debris Radar (NDR). This software provides a greatly improved analysis capacity over earlier manual processes, allowing for up to four times as much data to be analyzed by one-quarter of the personnel required by earlier methods. There are two applications that comprise the DEBRIS system: the Automated Radar Debris Examination Tool (ARDENT) and the primary DEBRIS tool.

  6. Protoplanetary and Debris Disk Morphologies

    NASA Astrophysics Data System (ADS)

    Lomax, Jamie R.; Wisniewski, John P.; Grady, Carol A.; McElwain, Michael W.; Hashimoto, Jun; Donaldson, Jessica; Debes, John H.; Malumuth, Eliot; Roberge, Aki; Weinberger, Alycia J.; SEEDS Team

    2016-01-01

    The types of planets that form around other stars are highly dependent on their natal disk conditions. Therefore, the composition, morphology, and distribution of material in protoplanetary and debris disks are important for planet formation. Here we present the results of studies of two disk systems: AB Aur and AU Mic.The circumstellar disk around the Herbig Ae star AB Aur has many interesting features, including spirals, asymmetries, and non-uniformities. However, comparatively little is known about the envelope surrounding the system. Recent work by Tang et al (2012) has suggested that the observed spiral armss may not in fact be in the disk, but instead are due to areas of increased density in the envelope and projection effects. Using Monte Carlo modeling, we find that it is unlikely that the envelope holds enough material to be responsible for such features and that it is more plausible that they form from disk material. Given the likelihood that gravitational perturbations from planets cause the observed spiral morphology, we use archival H band observations of AB Aur with a baseline of 5.5 years to determine the locations of possible planets.The AU Mic debris disk also has many interesting morphological features. Because its disk is edge on, the system is an ideal candidate for color studies using coronagraphic spectroscopy. Spectra of the system were taken by placing a HST/STIS long slit parallel to and overlapping the disk while blocking out the central star with an occulting fiducial bar. Color gradients may reveal the chemical processing that is occuring within the disk. In addition, it may trace the potential composition and architecture of any planetary bodies in the system because collisional break up of planetesimals produces the observed dust in the system. We present the resulting optical reflected spectra (5200 to 10,200 angstroms) from this procedure at several disk locations. We find that the disk is bluest at the innermost locations of the

  7. Debris ingestion by juvenile marine turtles: an underestimated problem.

    PubMed

    Santos, Robson Guimarães; Andrades, Ryan; Boldrini, Marcillo Altoé; Martins, Agnaldo Silva

    2015-04-15

    Marine turtles are an iconic group of endangered animals threatened by debris ingestion. However, key aspects related to debris ingestion are still poorly known, including its effects on mortality and the original use of the ingested debris. Therefore, we analysed the impact of debris ingestion in 265 green turtles (Chelonia mydas) over a large geographical area and different habitats along the Brazilian coast. We determined the death rate due to debris ingestion and quantified the amount of debris that is sufficient to cause the death of juvenile green turtles. Additionally, we investigated the original use of the ingested debris. We found that a surprisingly small amount of debris was sufficient to block the digestive tract and cause death. We suggested that debris ingestion has a high death potential that may be masked by other causes of death. An expressive part of the ingested debris come from disposable and short-lived products. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. An Assessment of the Current LEO Debris Environment and the Need for Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2010-01-01

    The anti-satellite test on the Fengun-1 C weather satellite in early 2007 and the collision between Iridium 33 and Cosmos 2251 in 2009 dramatically altered the landscape of the human-made orbital debris environment in the low Earth orbit (LEO). The two events generated approximately 5500 fragments large enough to be tracked by the U.S. Space Surveillance Network. Those fragments account for more than 60% increase to the debris population in LEO. However, even before the ASAT test, model analyses already indicated that the debris population (for those larger than 10 cm) in LEO had reached a point where the population would continue to increase, due to collisions among existing objects, even without any future launches. The conclusion implies that as satellites continue to be launched and unexpected breakup events continue to occur, commonly-adopted mitigation measures will not be able to stop the collision-driven population growth. To remediate the debris environment in LEO, active debris removal must be considered. This presentation will provide an updated assessment of the debris environment after the Iridium 33/Cosmos 2251 collision, an analysis of several future environment projections based on different scenarios, and a projection of collision activities in LEO in the near future. The need to use active debris removal to stabilize future debris environment will be demonstrated and the effectiveness of various active debris removal strategies will be quantified.

  9. NASA's Long-term Debris Environment and Active Debris Removal Modeling Activities

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.

    2009-01-01

    This slide presentation reviews the modeling activities for modeling of the long-term debris environment, the updated assessments of the environment, and the necessity to model the effectiveness of the technologies aimed at the removal of orbital debris. The model being used is named a LEO to GEO environment debris (LEGEND). It is a high fidelity three dimensional numerical simulation model with the capability to treat objects individually. It uses a Monte Carlo approach and a collision probability evaluation algorithm to simulate future satellite breakups and the growth of the debris populations.

  10. Comparison of an Inductance In-Line Oil Debris Sensor and Magnetic Plug Oil Debris Sensor

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Tuck, Roger; Showalter, Stephen

    2012-01-01

    The objective of this research was to compare the performance of an inductance in-line oil debris sensor and magnetic plug oil debris sensor when detecting transmission component health in the same system under the same operating conditions. Both sensors were installed in series in the NASA Glenn Spiral Bevel Gear Fatigue Rig during tests performed on 5 gear sets (pinion/gear) when different levels of damage occurred on the gear teeth. Results of this analysis found both the inductance in-line oil debris sensor and magnetic plug oil debris sensor have benefits and limitations when detecting gearbox component damage.

  11. Comparison of an Inductance In-Line Oil Debris Sensor and Magnetic Plug Oil Debris Sensor

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Tuck, Roger; Showalter, Stephen

    2012-01-01

    The objective of this research was to compare the performance of an inductance in-line oil debris sensor and magnetic plug oil debris sensor when detecting transmission component health in the same system under the same operating conditions. Both sensors were installed in series in the NASA Glenn Spiral Bevel Gear Fatigue Rig during tests performed on 5 gear sets (pinion/gear) when different levels of damage occurred on the gear teeth. Results of this analysis found both the inductance in-line oil debris sensor and magnetic plug oil debris sensor have benefits and limitations when detecting gearbox component damage.

  12. Spacelab J air filter debris analysis

    NASA Technical Reports Server (NTRS)

    Obenhuber, Donald C.

    1993-01-01

    Filter debris from the Spacelab module SLJ of STS-49 was analyzed for microbial contamination. Debris for cabin and avionics filters was collected by Kennedy Space Center personnel on 1 Oct. 1992, approximately 5 days postflight. The concentration of microorganisms found was similar to previous Spacelab missions averaging 7.4E+4 CFU/mL for avionics filter debris and 4.5E+6 CFU/mL for the cabin filter debris. A similar diversity of bacterial types was found in the two filters. Of the 13 different bacterial types identified from the cabin and avionics samples, 6 were common to both filters. The overall analysis of these samples as compared to those of previous missions shows no significant differences.

  13. Managing Debris After a Natural Disaster

    EPA Pesticide Factsheets

    Hauling Hurricane-related debris to the curb in participating areas. Following these specific guidelines (PDF) will make for a speedier removal process. Check with your local government on what is available to you.

  14. Remote sensing and characterization of anomalous debris

    NASA Technical Reports Server (NTRS)

    Sridharan, R.; Beavers, W.; Lambour, R.; Gaposchkin, E. M.; Kansky, J.; Stansbery, E.

    1997-01-01

    The analysis of orbital debris data shows a band of anomalously high debris concentration in the altitude range between 800 and 1000 km. Analysis indicates that the origin is the leaking coolant fluid from nuclear power sources that powered a now defunct Soviet space-based series of ocean surveillance satellites. A project carried out to detect, track and characterize a sample of the anomalous debris is reported. The nature of the size and shape of the sample set, and the possibility of inferring the composition of the droplets were assessed. The technique used to detect, track and characterize the sample set is described and the results of the characterization analysis are presented. It is concluded that the nature of the debris is consistent with leaked Na-K fluid, although this cannot be proved with the remote sensing techniques used.

  15. NASA-GSFC Orbital Debris Research Priorities

    NASA Technical Reports Server (NTRS)

    Hull, Scott M.

    2014-01-01

    While quite a lot is known about the orbital debris environment and how to limit its growth, more remains to be learned. The curent priorities for research and development, from the NASA Goddard Space Flight Center perspective, will be discussed.

  16. Orbital Debris Shape Characterization Project Abstract

    NASA Technical Reports Server (NTRS)

    Pease, Jessie

    2016-01-01

    I have been working on a project to further our understanding of orbital debris by helping create a new dataset previously too complex to be implemented in past orbital debris propagation models. I am doing this by creating documentation and 3D examples and illustrations of the shape categories. Earlier models assumed all orbital debris to be spherical aluminum fragments. My project will help expand our knowledge of shape populations to 6 categories: Straight Needle/Rod/Cylinder, Bent Needle/Rod/Cylinder, Flat Plate, Bent Plate, Nugget/Parallelepiped/Spheroid, and Flexible. The last category, Flexible, is still up for discussion and may be modified. These categories will be used to characterize fragments in the DebriSat experiment.

  17. Molecular Gas in Young Debris Disks

    NASA Astrophysics Data System (ADS)

    Moór, Attila; Kóspál, Ágnes; Ábrahám, Péter; Juhász, Attila; Apai, Dániel; Csengeri, Timea; Grady, Carol; Henning, Thomas; Kiss, Csaba; Pascucci, Ilaria

    2013-07-01

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. So far only a very few debris disks with measurable gas component have been known. We carried out a survey with the APEX radio telescope to detect molecular gas at millimeter wavelengths in 28 infrared-luminous young debris disks, and discovered two new systems with substantial amount of CO. Motivated to understand the origin, physics, and evolutionary status of the gas in these systems we observed one of them, HD 21997, with ALMA and Herschel. Our results suggest that HD 21997 may be a hybrid system where secondary debris dust and residual primordial gas coexist. This poses a serious question to the current paradigm, since the age of the system (30 Myr) significantly exceeds model predictions for disk clearing and the ages of the oldest transitional disks.

  18. Mountain Relief in Tropical Granitic Landscapes Spanning Diverse Tectonic Environments

    NASA Astrophysics Data System (ADS)

    Hilley, G. E.; Porder, S.; Aron, F.; Baden, C. W.; Johnstone, S. A.; Liu, F.; Sare, R.; Steelquist, A.; Young, H.

    2016-12-01

    Fluvial processes are thought to limit the relief on our planet, and in its simplest conception, this relief should scale with erosion rate as captured by a power-law incision rule. Existing studies attempting to quantify relationships between relief and erosion rate have been obfuscated by a lack of control of lithologies and climatic conditions across a broad (i.e., four orders-of-magnitude) erosion-rate gradient. We tested the power-law incision rule by systematically sampling tropical granitic landscapes that, in retrospect, spanned a four-and-a-half order-of-magnitude variation in erosion rate. We found that at low channel steepness values (calculated using an integral form of channel steepness), averaged channel steepness values scaled approximately linearly with erosion rate (determined using detrital 10Be erosion rates; n = 0.74, R-squared = 0.96). Inferred rock erodibility values for these conditions are in line with calibrated estimates in similar lithologies (K = 0.5-2.6 x 10-5 m0.2/yr). However, as channel steepness values approached 100 m0.8, channel steepnesses became insensitive to increasing erosion rate. Global compilations also show that every compiled sampled basin has channel steepness values < 100 m0.8, which is smaller than what would be expected given the range of observed erosion rates and calibrated values of the rock erodibility constant (K). Likewise, steepness values imaged using the HydroSheds 500m dataset are all < 200 m0.8, which is orders-of-magnitude less than what would be expected from extrapolation of erosion rate and steepness values in low-relief landscapes. This suggests that some process/processes (perhaps debris-flow incision, channel width-adjustments, or mass-failure) may limit inferences of erosion rate in steep landscapes, and may limit the total relief in active mountain belts on our planet.

  19. An adaptive strategy for active debris removal

    NASA Astrophysics Data System (ADS)

    White, Adam E.; Lewis, Hugh G.

    2014-04-01

    Many parameters influence the evolution of the near-Earth debris population, including launch, solar, explosion and mitigation activities, as well as other future uncertainties such as advances in space technology or changes in social and economic drivers that effect the utilisation of space activities. These factors lead to uncertainty in the long-term debris population. This uncertainty makes it difficult to identify potential remediation strategies, involving active debris removal (ADR), that will perform effectively in all possible future cases. Strategies that cannot perform effectively, because of this uncertainty, risk either not achieving their intended purpose, or becoming a hindrance to the efforts of spacecraft manufactures and operators to address the challenges posed by space debris. One method to tackle this uncertainty is to create a strategy that can adapt and respond to the space debris population. This work explores the concept of an adaptive strategy, in terms of the number of objects required to be removed by ADR, to prevent the low Earth orbit (LEO) debris population from growing in size. This was demonstrated by utilising the University of Southampton’s Debris Analysis and Monitoring Architecture to the Geosynchronous Environment (DAMAGE) tool to investigate ADR rates (number of removals per year) that change over time in response to the current space environment, with the requirement of achieving zero growth of the LEO population. DAMAGE was used to generate multiple Monte Carlo projections of the future LEO debris environment. Within each future projection, the debris removal rate was derived at five-year intervals, by a new statistical debris evolutionary model called the Computational Adaptive Strategy to Control Accurately the Debris Environment (CASCADE) model. CASCADE predicted the long-term evolution of the current DAMAGE population with a variety of different ADR rates in order to identify a removal rate that produced a zero net

  20. 33 CFR 151.3000 - Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Definition of marine debris for the purposes of the Marine Debris Research, Prevention, and Reduction Act. 151.3000 Section 151.3000... Definition of Marine Debris for the Purposes of the Marine Debris Research, Prevention, and Reduction Act...

  1. Analyzing costs of space debris mitigation methods

    NASA Astrophysics Data System (ADS)

    Wiedemann, C.; Krag, H.; Bendisch, J.; Sdunnus, H.

    The steadily increasing number of space objects poses a considerable hazard to all kinds of spacecraft. To reduce the risks to future space missions different debris mitigation measures and spacecraft protection techniques have been investigated during the last years. However, the economic efficiency has not been considered yet in this context. This economical background is not always clear to satellite operators and the space industry. Current studies have the objective to evaluate the mission costs due to space debris in a business as usual (no mitigation) scenario compared to the missions costs considering debris mitigation. The aim i an estimation of thes time until the investment in debris mitigation will lead to an effective reduction of mission costs. This paper presents the results of investigations on the key problems of cost estimation for spacecraft and the influence of debris mitigation and shielding on cost. The shielding of a satellite can be an effective method to protect the spacecraft against debris impact. Mitigation strategies like the reduction of orbital lifetime and de- or re-orbit of non-operational satellites are methods to control the space debris environment. These methods result in an increase of costs. In a first step the overall costs of different types of unmanned satellites are analyzed. The key problem is, that it is not possible to provide a simple cost model that can be applied to all types of satellites. Unmanned spacecraft differ very much in mission, complexity of design, payload and operational lifetime. It is important to classify relevant cost parameters and investigate their influence on the respective mission. The theory of empirical cost estimation and existing cost models are discussed. A selected cost model is simplified and generalized for an application on all operational satellites. In a next step the influence of space debris on cost is treated, if the implementation of mitigation strategies is considered.

  2. X-ray transmissive debris shield

    DOEpatents

    Spielman, Rick B.

    1994-01-01

    A composite window structure is described for transmitting x-ray radiation and for shielding radiation generated debris. In particular, separate layers of different x-ray transmissive materials are laminated together to form a high strength, x-ray transmissive debris shield which is particularly suited for use in high energy fluences. In one embodiment, the composite window comprises alternating layers of beryllium and a thermoset polymer.

  3. Deformation of debris-ice mixtures

    NASA Astrophysics Data System (ADS)

    Moore, Peter L.

    2014-09-01

    Mixtures of rock debris and ice are common in high-latitude and high-altitude environments and are thought to be widespread elsewhere in our solar system. In the form of permafrost soils, glaciers, and rock glaciers, these debris-ice mixtures are often not static but slide and creep, generating many of the landforms and landscapes associated with the cryosphere. In this review, a broad range of field observations, theory, and experimental work relevant to the mechanical interactions between ice and rock debris are evaluated, with emphasis on the temperature and stress regimes common in terrestrial surface and near-surface environments. The first-order variables governing the deformation of debris-ice mixtures in these environments are debris concentration, particle size, temperature, solute concentration (salinity), and stress. A key observation from prior studies, consistent with expectations, is that debris-ice mixtures are usually more resistant to deformation at low temperatures than their pure end-member components. However, at temperatures closer to melting, the growth of unfrozen water films at ice-particle interfaces begins to reduce the strengthening effect and can even lead to profound weakening. Using existing quantitative relationships from theoretical and experimental work in permafrost engineering, ice mechanics, and glaciology combined with theory adapted from metallurgy and materials science, a simple constitutive framework is assembled that is capable of capturing most of the observed dynamics. This framework highlights the competition between the role of debris in impeding ice creep and the mitigating effects of unfrozen water at debris-ice interfaces.

  4. Hot Wax Sweeps Debris From Narrow Passages

    NASA Technical Reports Server (NTRS)

    Ricklefs, Steven K.

    1990-01-01

    Safe and effective technique for removal of debris and contaminants from narrow passages involves entrainment of undesired material in thermoplastic casting material. Semisolid wax slightly below melting temperature pushed along passage by pressurized nitrogen to remove debris. Devised to clean out fuel passages in main combustion chamber of Space Shuttle main engine. Also applied to narrow, intricate passages in internal-combustion-engine blocks, carburetors, injection molds, and other complicated parts.

  5. Dimensional analysis of natural debris flows

    NASA Astrophysics Data System (ADS)

    Zhou, Gordon; Ouyang, Chaojun

    2015-04-01

    Debris flows occur when masses of poorly sorted sediment, agitated and saturated with water, surge down slopes in response to gravitational attraction. They are of great concern because they often cause catastrophic disasters due to the long run-out distance and large impact forc-es. Different from rock avalanches and sediment-laden water floods, both solid and fluid phases affected by multiple parameters can influence the motion of debris flows and govern their rheological properties. A dimensional analysis for a systematic study of the governing parameters is presented in this manuscript. Multiple dimensionless numbers with clear physical meanings are critically reviewed. Field data on natural debris flows are available here based on the fifty years' observation and measurement in the Jiangjia Gully, which is located in the Dongchuan City, Yunnan Province of China. The applications of field data with the dimensional analysis for studying natural debris flows are demonstrated. Specific values of dimensionless numbers (e.g., modified Savage Number, Reynolds number, Friction number) for classifying flowing regimes of natural debris flows on the large scales are obtained. Compared to previous physical model tests conducted mostly on small scales, this study shows that the contact friction between particles dominates in natural debris flows. In addition, the solid inertial stress due to particle collisions and the pore fluid viscous shear stress play key roles in governing the dynamic properties of debris flows and the total normal stress acting on the slope surfaces. The channel width as a confinement to the flows can affect the solids discharge per unit width significantly. Furthermore, a dimensionless number related to pore fluid pressure dissipation is found for distinguishing surge flows and continuous flows in field satisfactorily. It indicates that for surge debris flows, the high pore fluid pressures generated in granular body dissipate quite slowly and may

  6. DebriSat Hypervelocity Impact Test

    DTIC Science & Technology

    2015-08-01

    public release; distribution unlimited.  Targets: Scaled Multishock Shield, DebrisLV, and DebriSat  500-600 g hollow aluminum and nylon projectile...solar cells), NBK7 glass, titanium, sapphire, T1000 fiber, M55J carbon fiber, PVE film (sheet, wire ), kevlar, HDPE, polyurethane plastic, mylar...impact project. The design (Fig. 7) used a hollow aluminum cylinder made of 7075-T651 aluminum with a nylon sleeve. During assembly the aluminum

  7. Toward an operational use of debris-flow monitoring stations

    NASA Astrophysics Data System (ADS)

    Fontaine, Firmin; Bel, Coraline; Bellot, Hervé; Liébault, Frédéric

    2017-04-01

    The detection and the characterization of both debris flows and their occurrence conditions using monitoring stations was increasingly developed during the last two decades. The devices operate with various types of sensors and techniques, and in particular rain gauge, ground vibration sensors, flow stage sensors or video cameras. In case of debris-flow detection, such sensors make it possible to estimate the peak flow depth, the mean flow velocity, the flow discharge and the transported volume. These flow characteristics as well as the occurrence frequency are quantitative information relevant for hazard assessment. The multiplication of instrumented debris-flow prone sites could improve the evaluation of regional influences which affect, for instance, the occurrence conditions used in regional early-warning system. However, because debris-flow monitoring stations have to operate in harsh conditions and require both, strong maintenance and time-consuming post-processing, their use in operational context is still limited. A key element of the post-processing relies on the seismic signal from geophones. Indeed, such a signal is used for the recognition of the flow process involved and for estimating the surge velocity. Because very high frequency recording is not suitable for such monitoring stations, the seismic signal has to be conditioned while maintaining flow signature. We developed an electronic interface for analogically processing the raw signal, similarly to the so-called amplitude method: it allows us to preserve the signal energy while degrading the temporal resolution. For dealing with the continuum of sediment processes, from bedload transport to debris flow, but also with the sensor sensitivity to vibration source distance, the system has been adapted. A better characterization of the sediment transport process is expected. It should improve the automatic classification of rainfall events responsible for large, small and no flow occurrence. Finally

  8. Debris flow sensitivity to glacial-interglacial climate change - supply vs transport

    NASA Astrophysics Data System (ADS)

    D'Arcy, Mitch; Roda Boluda, Duna C.; Whittaker, Alexander C.

    2016-04-01

    Numerical models suggest that small mountain catchment-alluvial fan systems might be sensitive to climate changes over glacial-interglacial cycles, and record these palaeoclimate signals in the sedimentology of their deposits. However, these models are still largely untested, and the propagation of climate signals through simple sediment routing systems remains contentious. Here, we present detailed sedimentological records from 8 debris flow fan systems in Owens Valley, California, that capture the past ~ 120 ka of deposition. We identify a strong and sustained relationship between deposit grain size and palaeoclimate records over a full glacial-interglacial cycle, with significantly coarser-grained deposits found in warm and dry periods. Our data show that these systems are highly sensitive to climate with a rapid response timescale of < 10ka, which we attribute to rapid transfer from source to sink. This sensitive record might be explained by changes in sediment supply and/or changes in sediment mobilisation, and we evaluate these mechanisms quantitatively. We find little evidence that changes in catchment hypsometry, weathering patterns, past glaciation or sediment production can explain the grain size changes we observe on the fans. However we do find that grain size has increased exponentially with rising temperatures, at a rate that matches the intensification of storms with warming. As these debris flows are triggered by surface runoff during intense storms, we interpret that enhanced runoff rates in warm and stormy conditions are responsible for entraining larger clasts during debris flow initiation. This implies that debris flow fans might record signals of past storm intensity. Our study utilises field sedimentology and focuses on short transport distances (~ 10 km) and climate changes over ~ 1-100 ka timespans, but could additionally have important implications for how eroding landscapes might respond to future warming scenarios. We address the

  9. Reflectance spectroscopy characterization of space debris

    NASA Astrophysics Data System (ADS)

    Vananti, A.; Schildknecht, T.; Krag, H.

    2017-05-01

    When characterizing the space debris environment one important point is the identification of the physical properties of the space debris objects. Reflectance spectroscopy is a possible technique to study the surface material of these objects with observations from the ground. In this work the results collected from spectroscopy observations of space debris in orbit are presented. The observations were performed at the 1-m ESA Space Debris Telescope (ESASDT) in Tenerife equipped with a spectrograph in the 450-960 nm wavelength range. A preliminary classification using three different categories purely based on the shape and appearance of the spectra was proposed. Two debris objects with high AMR could be successfully associated with materials analyzed in the laboratory. The results show that the two debris objects are probably pieces of Kapton MLI with 'gold' and 'silver' coating, respectively. Color indices were extracted from the spectroscopic measurements. For high AMR objects the colors seem to be consistent with the proposed classification in three categories. The B-R and R-I laboratory measurements of 'gold' and 'silver' MLI taken from the literature are comparable with the obtained results.

  10. HOT DEBRIS DUST AROUND HD 106797

    SciTech Connect

    Fujiwara, Hideaki; Onaka, Takashi; Yamashita, Takuya; Ishihara, Daisuke; Kataza, Hirokazu; Ootsubo, Takafumi; Murakami, Hiroshi; Nakagawa, Takao; Hirao, Takanori; Enya, Keigo; Fukagawa, Misato; Marshall, Jonathan P.; White, Glenn J.

    2009-04-10

    Photometry of the A0 V main-sequence star HD 106797 with AKARI and Gemini/T-ReCS is used to detect excess emission over the expected stellar photospheric emission between 10 and 20 {mu}m, which is best attributed to hot circumstellar debris dust surrounding the star. The temperature of the debris dust is derived as T {sub d} {approx} 190 K by assuming that the excess emission is approximated by a single temperature blackbody. The derived temperature suggests that the inner radius of the debris disk is {approx}14 AU. The fractional luminosity of the debris disk is 1000 times brighter than that of our own zodiacal cloud. The existence of such a large amount of hot dust around HD 106797 cannot be accounted for by a simple model of the steady state evolution of a debris disk due to collisions, and it is likely that transient events play a significant role. Our data also show a narrow spectral feature between 11 and 12 {mu}m attributable to crystalline silicates, suggesting that dust heating has occurred during the formation and evolution of the debris disk of HD 106797.

  11. Engineering Challenges for Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2011-01-01

    Recent modeling studies on the instability of the debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have underlined the need for active debris removal. A 2009 analysis by the NASA Orbital Debris Program Office shows that, in order to maintain the LEO debris population at a constant level for the next 200 years, an active debris removal of about five objects per year is needed. The targets identified for removal are those with the highest mass and collision probability products in the environment. Many of these objects are spent upper stages with masses ranging from 1 to more than 8 metric tons, residing in several altitude regions and concentrated in about 10 inclination bands. To remove five of those objects on a yearly basis, in a cost-effective manner, represents many challenges in engineering, technology development, and operations. This paper outlines a conceptual end-to-end debris removal operation, including launch, precision tracking, rendezvous, stabilization (of the tumbling targets), capture, and deorbit of the targets; and highlights major challenges associated with the operations. Pros and cons of several proposed removal techniques are also evaluated.

  12. Conceptual design of an orbital debris collector

    NASA Technical Reports Server (NTRS)

    Odonoghue, Peter (Editor); Brenton, Brian; Chambers, Ernest; Schwind, Thomas; Swanhart, Christopher; Williams, Thomas

    1991-01-01

    The current Lower Earth Orbit (LEO) environment has become overly crowded with space debris. An evaluation of types of debris is presented in order to determine which debris poses the greatest threat to operation in space, and would therefore provide a feasible target for removal. A target meeting these functional requirements was found in the Cosmos C-1B Rocket Body. These launchers are spent space transporters which constitute a very grave risk of collision and fragmentation in LEO. The motion and physical characteristics of these rocket bodies have determined the most feasible method of removal. The proposed Orbital Debris Collector (ODC) device is designed to attach to the Orbital Maneuvering Vehicle (OMV), which provides all propulsion, tracking, and power systems. The OMV/ODC combination, the Rocket Body Retrieval Vehicle (RBRV), will match orbits with the rocket body, use a spin table to match the rotational motion of the debris, capture it, despin it, and remove it from orbit by allowing it to fall into the Earth's atmosphere. A disposal analysis is presented to show how the debris will be deorbited into the Earth's atmosphere. The conceptual means of operation of a sample mission is described.

  13. Marine debris survey manual. Final report

    SciTech Connect

    Ribic, C.A.; Dixon, T.R.; Vining, I.; Duke, M.

    1991-10-01

    Over the last several years, concern has increased about the amount of man-made materials lost or discarded at sea and the potential impacts to the environment. The scope of the problem depends on the amounts and types of debris. One problem is making a regional comparison of debris is the lack of a standard methodology. The objective of this manual is to discuss designs and methodologies for assessment studies of marine debris. This manual has been written for managers, researchers, and others who are just entering this area of study and who seek guidance in designing marine debris surveys. Active researchers will be able to use this manual along with applicable references herein as a source for design improvement. To this end, the authors have reviewed and synthesized survey techniques that have been used in the past for assessing marine debris, such as sighting surveys, beach surveys, and trawl surveys, and have considered new methods (e.g., aerial photography). All techniques have been put into a general survey planning framework to assist in developing different marine debris surveys.

  14. Detection of Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2014-01-01

    There have been extensive optical surveys for debris at geosynchronous orbit (GEO) conducted with meter-class telescopes, such as those conducted with MODEST (the Michigan Orbital DEbris Survey Telescope, a 0.6-m telescope located at Cerro Tololo in Chile), and the European Space Agency's 1.0-m space debris telescope (SDT) in the Canary Islands. These surveys have detection limits in the range of 18th or 19th magnitude, which corresponds to sizes larger than 10 cm assuming an albedo of 0.175. All of these surveys reveal a substantial population of objects fainter than R = 15th magnitude that are not in the public U.S. Satellite Catalog. To detect objects fainter than 20th magnitude (and presumably smaller than 10 cm) in the visible requires a larger telescope and excellent imaging conditions. This combination is available in Chile. NASA's Orbital Debris Program Office has begun collecting orbital debris observations with the 6.5-m (21.3-ft diameter) "Walter Baade" Magellan telescope at Las Campanas Observatory. The goal is to detect objects as faint as possible from a ground-based observatory and begin to understand the brightness distribution of GEO debris fainter than R = 20th magnitude.

  15. LDEF meteoroid and debris database

    NASA Astrophysics Data System (ADS)

    Dardano, C. B.; See, Thomas H.; Zolensky, Michael E.

    The Long Duration Exposure Facility (LDEF) Meteoroid and Debris Special Investigation Group (M&D SIG) database is maintained at the Johnson Space Center (JSC), Houston, Texas, and consists of five data tables containing information about individual features, digitized images of selected features, and LDEF hardware (i.e., approximately 950 samples) archived at JSC. About 4000 penetrations (greater than 300 micron in diameter) and craters (greater than 500 micron in diameter) were identified and photo-documented during the disassembly of LDEF at the Kennedy Space Center (KSC), while an additional 4500 or so have subsequently been characterized at JSC. The database also contains some data that have been submitted by various PI's, yet the amount of such data is extremely limited in its extent, and investigators are encouraged to submit any and all M&D-type data to JSC for inclusion within the M&D database. Digitized stereo-image pairs are available for approximately 4500 features through the database.

  16. Micrometeoroids and debris on LDEF

    NASA Technical Reports Server (NTRS)

    Mandeville, Jean-Claude

    1993-01-01

    Two experiments within the French Cooperative Payload (FRECOPA) and devoted to the detection of cosmic dust were flown on the Long Duration Exposure Facility (LDEF). A variety of sensors and collecting devices have made possible the study of impact processes on dedicated sensors and on materials of technological interest. Examination of hypervelocity impact features on these experiments gives valuable information on the size distribution and nature of interplanetary dust particles in low-Earth orbit (LEO), within the 0.5-300 micrometer size range. However no crater smaller than 1.5 microns has been observed, thus suggesting a cut-off in the near Earth particle distribution. Chemical investigation of craters by EDX clearly shows evidence of elements (Na, Mg, Si, S, Ca, and Fe) consistent with cosmic origin. However, remnants of orbital debris have been found in a few craters; this can be the result of particles in eccentric orbits about the Earth and of the 8 deg offset in the orientation of LDEF. Crater size distribution is compared with results from other dust experiments flown on LDEF and with current models. Possible origin and orbital evolution of micrometeoroids is discussed. Use of thin foil detectors for the chemical study of particle remnants looks promising for future experiments.

  17. Postdetonation nuclear debris for attribution.

    PubMed

    Fahey, A J; Zeissler, C J; Newbury, D E; Davis, J; Lindstrom, R M

    2010-11-23

    On the morning of July 16, 1945, the first atomic bomb was exploded in New Mexico on the White Sands Proving Ground. The device was a plutonium implosion device similar to the device that destroyed Nagasaki, Japan, on August 9 of that same year. Recently, with the enactment of US public law 111-140, the "Nuclear Forensics and Attribution Act," scientists in the government and academia have been able, in earnest, to consider what type of forensic-style information may be obtained after a nuclear detonation. To conduct a robust attribution process for an exploded device placed by a nonstate actor, forensic analysis must yield information about not only the nuclear material in the device but about other materials that went into its construction. We have performed an investigation of glassed ground debris from the first nuclear test showing correlations among multiple analytical techniques. Surprisingly, there is strong evidence, obtainable only through microanalysis, that secondary materials used in the device can be identified and positively associated with the nuclear material.

  18. Postdetonation nuclear debris for attribution

    PubMed Central

    Fahey, A. J.; Zeissler, C. J.; Newbury, D. E.; Davis, J.; Lindstrom, R. M.

    2010-01-01

    On the morning of July 16, 1945, the first atomic bomb was exploded in New Mexico on the White Sands Proving Ground. The device was a plutonium implosion device similar to the device that destroyed Nagasaki, Japan, on August 9 of that same year. Recently, with the enactment of US public law 111-140, the “Nuclear Forensics and Attribution Act,” scientists in the government and academia have been able, in earnest, to consider what type of forensic-style information may be obtained after a nuclear detonation. To conduct a robust attribution process for an exploded device placed by a nonstate actor, forensic analysis must yield information about not only the nuclear material in the device but about other materials that went into its construction. We have performed an investigation of glassed ground debris from the first nuclear test showing correlations among multiple analytical techniques. Surprisingly, there is strong evidence, obtainable only through microanalysis, that secondary materials used in the device can be identified and positively associated with the nuclear material. PMID:21059943

  19. How to implement data for improved modelling - Results from an extensive field campaign on the debris covered Lirung Glacier in the Nepalese Himalayas

    NASA Astrophysics Data System (ADS)

    Petersen, Lene; Immerzeel, Walter; Shahi, Sonika; Baral, Prashant; Pellicciotti, Francesca

    2013-04-01

    Debris covered glaciers have become a focus of current research because of growing evidence of an increase in debris cover associated with a warming climate and the effect that debris has on melt rates. Mass balance models increasingly aim at including the melt rate enhancing/reduction effect due to a thin/thick debris layer, respectively. However, knowledge about debris cover and thickness, its distribution and characteristics is limited and data are scarce, especially in the HKKH region where debris-covered glaciers are numerous. In this work we present a data set that is complementary to modelling efforts carried out to improve our understanding of processes occurring at the debris cover surface and how debris effects can be implemented into melt and mass balance models of different complexity. A key requirement for distributed melt modelling is the availability of debris cover and thickness maps and knowledge about characteristics of the debris layer and their spatial variability. An extensive field campaign was conducted from May to October 2012 on the debris covered Lirung Glacier in the Nepalese Himalayas. The collected data set consists of observations from an automatic weather station (AWS) measuring wind direction, wind speed, air and surface temperature, incoming and outgoing shortwave radiation, relative humidity and snow height, 14 sensors measuring 2 m air temperature and 7 surface temperature sensors, 3 temperature systems (tinytags) measuring temperature at the debris surface and the ice below the debris layer and one thermistors chain (with 8 temperature sensors) measuring the temperature profile in the debris layer. In the study region there is a key difference between meteorological conditions during monsoon and the dry period. We analyze separately all meteorological records for these different climatic conditions and show how temperature, albedo, relative humidity and wind speed and direction are affected. Wind speed and direction show similar

  20. Active Debris Removal Using Modified Launch Vehicle Upper Stages

    NASA Astrophysics Data System (ADS)

    Nasseri, S. Ali; Emanuelli, Matteo; Raval, Siddharth; Turconi, Andrea

    2013-09-01

    During the past few years, several research programs have assessed the current state and future evolution of space debris in the Low Earth Orbit region. These studies indicate that space debris density could reach a critical level such that there will be a continuous increase in the number of debris objects, primarily driven by debris-debris collision activity known as the Kessler effect. These studies also highlight the urgency for active debris removal.An Active Debris Removal System (ADRS) is capable of approaching the debris object through a close-range rendezvous, stabilizing its attitude, establishing physical contact, and finally de-orbiting the debris object. The de-orbiting phase could be powered by propulsion systems such as chemical rockets or electrodynamic tether (EDT) systems.The aim of this project is to model and evaluate a debris removal mission in which an adapted rocket upper stage, equipped with an electrodynamic tether (EDT) system, is employed for de-orbiting a debris object. This ADRS package is installed initially as part of a launch vehicle on a normal satellite deployment mission, and a far-approach manoeuvre will be required to align the ADRS' orbit with that of the target debris. We begin by selecting a suitable target debris and launch vehicle, and then proceed with modelling the entire debris removal mission from launch to de-orbiting of the target debris object using Analytical Graphic Inc.'s Systems Tool Kit (STK).

  1. Global analysis of anthropogenic debris ingestion by sea turtles.

    PubMed

    Schuyler, Qamar; Hardesty, Britta Denise; Wilcox, Chris; Townsend, Kathy

    2014-02-01

    Ingestion of marine debris can have lethal and sublethal effects on sea turtles and other wildlife. Although researchers have reported on ingestion of anthropogenic debris by marine turtles and implied incidences of debris ingestion have increased over time, there has not been a global synthesis of the phenomenon since 1985. Thus, we analyzed 37 studies published from 1985 to 2012 that report on data collected from before 1900 through 2011. Specifically, we investigated whether ingestion prevalence has changed over time, what types of debris are most commonly ingested, the geographic distribution of debris ingestion by marine turtles relative to global debris distribution, and which species and life-history stages are most likely to ingest debris. The probability of green (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) ingesting debris increased significantly over time, and plastic was the most commonly ingested debris. Turtles in nearly all regions studied ingest debris, but the probability of ingestion was not related to modeled debris densities. Furthermore, smaller, oceanic-stage turtles were more likely to ingest debris than coastal foragers, whereas carnivorous species were less likely to ingest debris than herbivores or gelatinovores. Our results indicate oceanic leatherback turtles and green turtles are at the greatest risk of both lethal and sublethal effects from ingested marine debris. To reduce this risk, anthropogenic debris must be managed at a global level.

  2. A globally complete map of supraglacial debris cover and a new toolkit for debris cover research

    NASA Astrophysics Data System (ADS)

    Herreid, Sam; Pellicciotti, Francesca

    2017-04-01

    A growing canon of literature is focused on resolving the processes and implications of debris cover on glaciers. However, this work is often confined to a handful of glaciers that were likely selected based on criteria optimizing their suitability to test a specific hypothesis or logistical ease. The role of debris cover in a glacier system is likely to not go overlooked in forthcoming research, yet the magnitude of this role at a global scale has not yet been fully described. Here, we present a map of debris cover for all glacierized regions on Earth including the Greenland Ice Sheet using 30 m Landsat data. This dataset will begin to open a wider context to the high quality, localized findings from the debris-covered glacier research community and help inform large-scale modeling efforts. A global map of debris cover also facilitates analysis attempting to isolate first order geomorphological and climate controls of supraglacial debris production. Furthering the objective of expanding the inclusion of debris cover in forthcoming research, we also present an under development suite of open-source, Python based tools. Requiring minimal and often freely available input data, we have automated the mapping of: i) debris cover, ii) ice cliffs, iii) debris cover evolution over the Landsat era and iv) glacier flow instabilities from altered debris structures. At the present time, debris extent is the only globally complete quantity but with the expanding repository of high quality global datasets and further tool development minimizing manual tasks and computational cost, we foresee all of these tools being applied globally in the near future.

  3. Probabilistic forecasts of debris-flow hazard at the regional scale with a combination of models.

    NASA Astrophysics Data System (ADS)

    Malet, Jean-Philippe; Remaître, Alexandre

    2015-04-01

    Debris flows are one of the many active slope-forming processes in the French Alps, where rugged and steep slopes mantled by various slope deposits offer a great potential for triggering hazardous events. A quantitative assessment of debris-flow hazard requires the estimation, in a probabilistic framework, of the spatial probability of occurrence of source areas, the spatial probability of runout areas, the temporal frequency of events, and their intensity. The main objective of this research is to propose a pipeline for the estimation of these quantities at the region scale using a chain of debris-flow models. The work uses the experimental site of the Barcelonnette Basin (South French Alps), where 26 active torrents have produced more than 150 debris-flow events since 1850 to develop and validate the methodology. First, a susceptibility assessment is performed to identify the debris-flow prone source areas. The most frequently used approach is the combination of environmental factors with GIS procedures and statistical techniques, integrating or not, detailed event inventories. Based on a 5m-DEM and derivatives, and information on slope lithology, engineering soils and landcover, the possible source areas are identified with a statistical logistic regression model. The performance of the statistical model is evaluated with the observed distribution of debris-flow events recorded after 1850 in the study area. The source areas in the three most active torrents (Riou-Bourdoux, Faucon, Sanières) are well identified by the model. Results are less convincing for three other active torrents (Bourget, La Valette and Riou-Chanal); this could be related to the type of debris-flow triggering mechanism as the model seems to better spot the open slope debris-flow source areas (e.g. scree slopes), but appears to be less efficient for the identification of landslide-induced debris flows. Second, a susceptibility assessment is performed to estimate the possible runout distance

  4. Optimal decomposable witnesses without the spanning property

    SciTech Connect

    Augusiak, Remigiusz; Sarbicki, Gniewomir; Lewenstein, Maciej

    2011-11-15

    One of the unsolved problems in the characterization of the optimal entanglement witnesses is the existence of optimal witnesses acting on bipartite Hilbert spaces H{sub m,n}=C{sup m} x C{sup n} such that the product vectors obeying =0 do not span H{sub m,n}. So far, the only known examples of such witnesses were found among indecomposable witnesses, one of them being the witness corresponding to the Choi map. However, it remains an open question whether decomposable witnesses exist without the property of spanning. Here we answer this question affirmatively, providing systematic examples of such witnesses. Then, we generalize some of the recently obtained results on the characterization of 2 x n optimal decomposable witnesses [R. Augusiak et al., J. Phys. A 44, 212001 (2011)] to finite-dimensional Hilbert spaces H{sub m,n} with m,n{>=}3.

  5. Career development: a life span issue.

    PubMed

    Sterns, H L; Dorsett, J G

    1994-01-01

    One of the challenges for individuals pursuing a career throughout their life span is how to maintain a high level of professional competence. As the composition of the workforce changes, and new technologies are developed, workers are faced with changing job demands and pressures. A major issue for the 1990s is how long a worker's skills will remain current. With rapid technological changes, workers may find it necessary to update continually their knowledge, skills, and abilities or risk becoming obsolete. Factors such as individuals' motivation and attitudes and organizational climate can contribute to choices regarding career development. Current research on the factors that contribute to career development activities is reviewed, along with the impact of multiple career transitions throughout the life span. Interventions such as retraining and outplacement, which allow individuals in later life to continue work, change jobs, and further develop their careers, are also discussed.

  6. The Cost of Uncertain Life Span*

    PubMed Central

    Edwards, Ryan D.

    2012-01-01

    A considerable amount of uncertainty surrounds the length of human life. The standard deviation in adult life span is about 15 years in the U.S., and theory and evidence suggest it is costly. I calibrate a utility-theoretic model of preferences over length of life and show that one fewer year in standard deviation is worth about half a mean life year. Differences in the standard deviation exacerbate cross-sectional differences in life expectancy between the U.S. and other industrialized countries, between rich and poor countries, and among poor countries. Accounting for the cost of life-span variance also appears to amplify recently discovered patterns of convergence in world average human well-being. This is partly for methodological reasons and partly because unconditional variance in human length of life, primarily the component due to infant mortality, has exhibited even more convergence than life expectancy. PMID:22368324

  7. Spatial abilities across the adult life span.

    PubMed

    Borella, Erika; Meneghetti, Chiara; Ronconi, Lucia; De Beni, Rossana

    2014-02-01

    The study investigates age-related effects across the adult life span on spatial abilities (testing subabilities based on a distinction between spatial visualization, mental rotation, and perspective taking) and spatial self-assessments. The sample consisted of 454 participants (223 women and 231 men) from 20 to 91 years of age. Results showed nonlinear age-related effects for spatial visualization and perspective taking but linear effects for mental rotation; few or no age-related effects were found for spatial self-assessments. Working memory accounted for only a small proportion of the variance in all spatial tasks and had no effect on spatial self-assessments. Overall, our findings suggest that the influence of age on spatial skills across the adult life span is considerable, but the effects of age change as a function of the spatial task considered, and the effect on spatial self-assessment is more marginal.

  8. Radar-based observatiions of variable thickness debris cover on martian ice masses: evidence of debris transfer by flowing ice on Mars

    NASA Astrophysics Data System (ADS)

    Souness, Colin; Brough, Stephen; Woodward, John; Hubbard, Bryn; Davis, Joel; Grindrod, Peter

    2016-04-01

    The mid-latitudes of Mars host a wide range of ice-based landforms, many of which display surface morphologies indicative of viscous flow of that ice. Despite being shrouded beneath a layer of rocky debris, these viscous flow features (VFFs) are thought to have similarities with terrestrial glaciers. Until recently most studies that focussed on the origin, structure and role of these martian VFFs were restricted to observations made from satellite imagery. Little data have been available to gain a clearer picture of VFF internal structure, which has impeded our collective ability to infer many particulars of VFF growth and flow, including the extent to which these ice flows have interacted with, and potentially helped shape, the martian landscape. However, the Shallow Radar (SHARAD) system mounted on the Mars Reconnaissance Orbiter (MRO) can, in some cases, provide a valuable insight into what lies beneath the surface of these ice masses. We present a SHARAD-based study of glacial systems on Mars which reveals pronounced heterogeneity in the thickness of their observed superficial debris covers. The surface debris layers in question appear to thicken in a down-slope direction. Radar data indicates that in the lower reaches of each studied glacial catchment, ice surface debris cover exceeds 10 m in thickness. The observed flow-parallel a-symmetry in debris thickness atop these martian glaciers is similar to that recorded on many terrestrial glaciers, indicating that cumulative down-flow debris mass transfer such as occurs within glacierised catchments on Earth may also currently operate, or have operated, on Mars. This suggests that glaciers on Mars have played a substantial role in redistributing lithic material from mountainous catchments to lower-lying areas, potentially throughout the glacial regions of Mars' mid-latitudes, thus making an important processual contribution to the evolution of Mars' contemporary landscape.

  9. Plastic Beaches: occurrence and accumulation of marine debris on barrier islands in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Wessel, C.; Albins, K.; Cebrian, J.

    2016-02-01

    Marine debris is any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment (33USC§1951). Marine debris is an economic, environmental, human health and aesthetic problem posing a complex challenge. Coastal communities are among the most seriously affected because of increased expenses for beach cleaning, public health and waste disposal, as well as a loss of income from decreased tourism. To better document this problem we are monitoring the occurrence and accumulation rate of marine debris on 6 barrier islands in the northern Gulf of Mexico (nGoM). Surveys are conducted at low tide and consist of 100m-long transects along the shoreline extending from the water edge to the upland shoreline limit. All debris larger than 5 mm is collected and recorded. Debris is then sorted by material, and dry mass is recorded. With this information we are investigating four specific questions: (1) what are the major types and possible sources (land or ocean based) of shoreline debris; (2) does the rate of debris deposition onto the shoreline show seasonal oscillations; (3) how does debris deposition change from east to west in the nGoM; and (4) what are the possible causes of the temporal and spatial trends found (e.g. rainfall and runoff, human population, boat traffic)? During the first year of sampling we are beginning to see trends emerge. More trash consistently washes up on the ocean side versus the sound side of the barrier islands, which suggests either large amounts of trash in the nGoM is ocean-based debris, or it is driven by beach goers, or both. In addition, we have found a significant increase in the amount of trash on the shoreline during tourist/boating season (May to September), although trash items tend to be smaller in size during that season. At the presentation we will discuss these and other trends that emerge with a more complete data set.

  10. A real-scale field experiment of debris flow for investigating its deposition and entrainment

    NASA Astrophysics Data System (ADS)

    Paik, J.; Son, S.; Kim, T.; Kim, S.

    2012-12-01

    In mountain area debris flows typically mobilize from slides and entrain channel materials as they propagate down over the surface of hill slope and valley. Consequently, cross-sectional averaged discharge of debris flows may increases due to the entrainment of channel materials over steep slopes while decrease due to deposition of large material at mile slopes. In this work, the erosional and depositional patterns of debris flow have been investigated through a real-scale field experiment in a mountain basin in Gangwon, Korea. The experimental basin is about 800 m long and the channel width ranges between 8 m and 25 m. The angle of the channel slope varies from 38° near the upstream end to 5° at the downstream end where a check has been installed. In the experiment, 300 cubic meters of saturated solid-fluid mixture is suddenly released by opening a gate of a concrete reservoir installed at the upstream of the basin, along with additional 10.0 cubic meters of water per second for 30 seconds. We employ several sensors for measuring the speed, depth variation and total normal and fluid pore pressures at the channel bed as the debris flow propagates downslope. The velocity and depth of the debris flow are measured using ultrasonic sensors with a measuring range up to 10 m and video recording systems. A load cell and eight pore pressure transducers ranging up 30 psia are used to measure the total normal and pore-water pressures at the base of the debris flow. Through a quantitative analysis of these experimental measurements and high-resolution LiDAR topographic data we investigate the deposition and entrainment features of debris flow. We introduce the details of the full-scale experimental basin, facility, sensors and procedure, and provide some our experimental observations.

  11. Field investigations of the interaction between debris flows and forest vegetation in two Alpine fans

    NASA Astrophysics Data System (ADS)

    Michelini, Tamara; Bettella, Francesco; D'Agostino, Vincenzo

    2017-02-01

    A key objective in debris-flow hazard mitigation is the reduction of the potential depositional area in the fan. From this point of view, forested areas are able to provide a protective function hindering the flow motion and promoting the surge deposition. Despite extensive research on Alpine forests and their protective functions, relatively few studies in the literature have quantitatively focused on the relationship between debris-flow depositional features and vegetation. In light of the above, our research investigates how vegetation characteristics in the fan area interact with debris-flow deposition. Field investigations were carried out in two Alpine fans where debris-flow events occurred in the summer of 2012. By recording the characteristics of 1567 involved trees and the associated deposit thicknesses, this paper provides a data set that contributes to the improvement of the knowledge of these interaction processes. The integration of literature findings and the analysis of the collected dataset adds insights into the relationships between tree characteristics and the dynamics of debris flow during the runout path. The main results prove the capacity of the forest of uniformly promoting flow-energy dissipation, presence of high species diversity in debris-flow deposits when comparing disturbed and undisturbed forest stands, tree mortality largely affecting small diameters < 10 cm in the upper/medium part of the cone, and deposit thicknesses depending on the trunk diameter only if the debris-flow regime was collisional. Based on the field results and their analysis, some criteria for the management of protection forests in alluvial fans are suggested.

  12. Attitudes Toward Death Across the Life Span.

    ERIC Educational Resources Information Center

    Maiden, Robert; Walker, Gail

    To understand the change and development of people's attitudes toward death over the life span, a 62-item attitude questionnaire on death and dying was administered to 90 adults. Participants included five females and five males in each of nine age categories: 18-20, 20-24, 25-29, 30-34, 35-39, 40-49, 50-59, 60-64, and 65 or older. Participants…

  13. Vision in Flies: Measuring the Attention Span

    PubMed Central

    Koenig, Sebastian; Wolf, Reinhard; Heisenberg, Martin

    2016-01-01

    A visual stimulus at a particular location of the visual field may elicit a behavior while at the same time equally salient stimuli in other parts do not. This property of visual systems is known as selective visual attention (SVA). The animal is said to have a focus of attention (FoA) which it has shifted to a particular location. Visual attention normally involves an attention span at the location to which the FoA has been shifted. Here the attention span is measured in Drosophila. The fly is tethered and hence has its eyes fixed in space. It can shift its FoA internally. This shift is revealed using two simultaneous test stimuli with characteristic responses at their particular locations. In tethered flight a wild type fly keeps its FoA at a certain location for up to 4s. Flies with a mutation in the radish gene, that has been suggested to be involved in attention-like mechanisms, display a reduced attention span of only 1s. PMID:26848852

  14. Improving Memory Span in Children with Down Syndrome

    ERIC Educational Resources Information Center

    Conners, F. A.; Rosenquist, C. J.; Arnett, L.; Moore, M. S.; Hume, L. E.

    2008-01-01

    Background: Down syndrome (DS) is characterized by impaired memory span, particularly auditory verbal memory span. Memory span is linked developmentally to several language capabilities, and may be a basic capacity that enables language learning. If children with DS had better memory span, they might benefit more from language intervention. The…

  15. 9. VIEW SHOWING JUNCTION OF CONCRETE EAST APPROACH SPAN WITH ...

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

    9. VIEW SHOWING JUNCTION OF CONCRETE EAST APPROACH SPAN WITH STEEL SPAN, LOOKING NORTH. NOTE ROCKING CAST STEEL SHOE ATTACHED TO PIER TO ALLOW FOR EXPANSION OF STEEL SPAN - Jensen Bridge, Spanning Green River at Town of Jensen, Jensen, Uintah County, UT

  16. Improving Memory Span in Children with Down Syndrome

    ERIC Educational Resources Information Center

    Conners, F. A.; Rosenquist, C. J.; Arnett, L.; Moore, M. S.; Hume, L. E.

    2008-01-01

    Background: Down syndrome (DS) is characterized by impaired memory span, particularly auditory verbal memory span. Memory span is linked developmentally to several language capabilities, and may be a basic capacity that enables language learning. If children with DS had better memory span, they might benefit more from language intervention. The…

  17. Investigation of Bearing Fatigue Damage Life Prediction Using Oil Debris Monitoring

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Bolander, Nathan; Haynes, Chris; Toms, Allison M.

    2011-01-01

    Research was performed to determine if a diagnostic tool for detecting fatigue damage of helicopter tapered roller bearings can be used to determine remaining useful life (RUL). The taper roller bearings under study were installed on the tail gearbox (TGB) output shaft of UH- 60M helicopters, removed from the helicopters and subsequently installed in a bearing spall propagation test rig. The diagnostic tool was developed and evaluated experimentally by collecting oil debris data during spall progression tests on four bearings. During each test, data from an on-line, in-line, inductance type oil debris sensor was monitored and recorded for the occurrence of pitting damage. Results from the four bearings tested indicate that measuring the debris generated when a bearing outer race begins to spall can be used to indicate bearing damage progression and remaining bearing life.

  18. Entanglement of Steller sea lions (Eumetopias jubatus) in marine debris: identifying causes and finding solutions.

    PubMed

    Raum-Suryan, Kimberly L; Jemison, Lauri A; Pitcher, Kenneth W

    2009-10-01

    Entanglement in marine debris is a contributing factor in Steller sea lion (SSL; Eumetopias jubatus) injury and mortality. We quantified SSL entanglement by debris type, sex and age class, entanglement incidence, and estimated population level effects. Surveys of SSL haul-outs were conducted from 2000-2007 in Southeast Alaska and northern British Columbia. We recorded 386 individuals of all age classes as being either entangled in marine debris or having ingested fishing gear. Packing bands were the most common neck entangling material (54%), followed by rubber bands (30%), net (7%), rope (7%), and monofilament line (2%). Ingested fishing gear included salmon fishery flashers (lures: 80%), longline gear (12%), hook and line (4%), spinners/spoons (2%), and bait hooks (2%). Entanglement incidence was 0.26% (SD=0.0064, n=69 sites). "Lose the Loop!" Simple procedures such as cutting entangling loops of synthetic material and eliminating the use of packing bands can prevent entanglements.

  19. Meteoroid and debris special investigation group data acquisition procedures

    NASA Technical Reports Server (NTRS)

    See, Thomas H.; Allbrooks, Martha K.; Atkinson, Dale R.; Sapp, Clyde A.; Simon, Charles G.; Zolensky, Mike E.

    1992-01-01

    The entire LDEF spacecraft was examined by M&D SIG for impact (i.e., craters greater than or = 0.5 mm and penetrations greater than or = 0.3 mm in diameter) and related features (e.g., debris, secondaries). During the various detailed surveys conducted at NASA Kennedy, approx. 5,000 impact related features were photodocumented, and their locations measured and recorded; an additional approx. 30,000 smaller features were counted. The equipment and techniques used by the M&D SIG permitted the determination and recording of the locations and diameters of the 5,000 imaged features. A variety of experimental and LDEF structural hardware was acquired by the M&D SIG and is presently being examined and curated at NASA Johnson.

  20. Evidence for enhanced debris-flow activity in the Northern Calcareous Alps since the 1980s (Plansee, Austria)

    NASA Astrophysics Data System (ADS)

    Dietrich, A.; Krautblatter, M.

    2017-06-01

    Debris flows are among the most important natural hazards. The Northern Calcareous Alps with their susceptible lithology are especially affected by a double digit number of major hazard events per year. It is hypothesised that debris-flow intensity has increased significantly in the last decades in the Northern Calcareous Alps coincident to increased rainstorm frequencies, but yet there is only limited evidence. The Plansee catchment exposes extreme debris-flow activity due to the intensely jointed Upper Triassic Hauptdolomit lithology, being responsible for most of the debris-flow activity in the Northern Calcareous Alps. The debris flows feed into a closed sediment system, the Plansee Lake, where Holocene/Lateglacial sedimentation rates, rates since the late 1940s and recent rates can be inferred accurately. Using aerial photos and field mapping, the temporal and spatial development of eight active debris-flow fans is reconstructed in six time intervals from 1947, 1952, 1971, 1979, 1987, 2000 and 2010 and mean annual debris-flow volumes are calculated. These are compared with mean Holocene/Lateglacial debris-flow volumes derived from the most prominent cone whose contact with the underlying till is revealed by electrical resistivity tomography (ERT). Debris-flow activity there increased by a factor of 10 from 1947-1952 (0.23 ± 0.07 · 103 m3/yr) to 1987-2000 (2.41 ± 0.66 · 103 m3/yr). Mean post-1980 rates from all eight fans exceed pre-1980 rates by a factor of more than three coinciding with enhanced rainstorm activity recorded at meteorological stations in the Northern Calcareous Alps. The frequency of rain storms (def. 35 mm/d) has increased in the study area on average by 10% per decade and has nearly doubled since 1921. Recent debris-flow activity is also 2-3 times higher than mean Holocene/Lateglacial rates. The strong correlation between the non-vegetated catchment area and the annual debris-flow volume might indicate a decadal positive feedback between

  1. Erosion and deposition on a debris-flow fan

    NASA Astrophysics Data System (ADS)

    Densmore, A. L.; Schuerch, P.; Rosser, N. J.; McArdell, B. W.

    2011-12-01

    a 2d numerical model of debris-flow fan evolution to explore the key controls on debris-flow routing and topographic development over sequences of multiple flows. We find that fan topographic roughness plays an important role in both channel development and fan surface stability. We also find that, while first-order fan shape is largely insensitive to the input flow sequence, second-order variables such as the pattern of surface exposure ages and the distribution of channel characteristics hold more promise as robust recorders of past flow conditions. Further work is needed to understand the degree to which the TLS-derived (and Illgraben-specific) relationship between bed elevation change and flow depth can be applied in different settings, and to elucidate the role played by coarse debris in controlling patterns of erosion and deposition.

  2. Laser system for space debris cleaning

    NASA Astrophysics Data System (ADS)

    Rubenchik, A. M.; Erlandson, A. C.; Liedahl, D.

    2012-07-01

    Starting with intensity requirements for producing efficient ablation thrust, then applying orbital mechanics and taking beam transport into account, we have determined the laser pulse energy and the number of pulses required for removing orbital debris. Our calculations show that a ground-based, diode-pumped, gas-cooled multi-slab laser, that uses only modest extensions of existing technology, would be capable of removing most small debris from low-earth orbit, when used with a 3-m-diameter beam director. Such a laser would also be capable of moving large debris into orbits that avoid high-value satellites and of even removing large debris from orbit, by illuminating the debris over several encounters. The laser design we propose uses diode-pumped, Nd:glass, gas-cooled amplifiers with 25-cm square apertures. When operating at the laser fundamental wavelength of 1054 nm, each beamline would produce ˜ 8kJ/4ns pulses at 15 Hz. Two such beamlines, combined using established polarization-combining methods, would be sufficient for orbital debris cleaning. Alternatively, when operating at the second harmonic of 527 nm, each beamline would produce ˜ 7 kJ/4 ns pulses. Due to reduced beam divergence and a smaller beam diameter at the debris, a single harmonically-converted beamline can be useful. We estimate that the first-of-a-kind beamline could be deployed within 4-5 years of project start at a cost of 100-150M. Later beamlines would require less development and engineering costs and would have substantially lower overall cost.

  3. Orbital Debris Engineering Model (ORDEM) v.3

    NASA Technical Reports Server (NTRS)

    Matney, Mark; Krisko, Paula; Xu, Yu-Lin; Horstman, Matthew

    2013-01-01

    A model of the manmade orbital debris environment is required by spacecraft designers, mission planners, and others in order to understand and mitigate the effects of the environment on their spacecraft or systems. A manmade environment is dynamic, and can be altered significantly by intent (e.g., the Chinese anti-satellite weapon test of January 2007) or accident (e.g., the collision of Iridium 33 and Cosmos 2251 spacecraft in February 2009). Engineering models are used to portray the manmade debris environment in Earth orbit. The availability of new sensor and in situ data, the re-analysis of older data, and the development of new analytical and statistical techniques has enabled the construction of this more comprehensive and sophisticated model. The primary output of this model is the flux [#debris/area/time] as a function of debris size and year. ORDEM may be operated in spacecraft mode or telescope mode. In the former case, an analyst defines an orbit for a spacecraft and "flies" the spacecraft through the orbital debris environment. In the latter case, an analyst defines a ground-based sensor (telescope or radar) in terms of latitude, azimuth, and elevation, and the model provides the number of orbital debris traversing the sensor's field of view. An upgraded graphical user interface (GUI) is integrated with the software. This upgraded GUI uses project-oriented organization and provides the user with graphical representations of numerous output data products. These range from the conventional flux as a function of debris size for chosen analysis orbits (or views), for example, to the more complex color-contoured two-dimensional (2D) directional flux diagrams in local spacecraft elevation and azimuth.

  4. Searching for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Abercromby, Kira J.; Barker, Edwin S.; Burkhardt, Andrew; Cowardin, Heather; Krisko, Paula; Silha, Jiri

    2012-01-01

    We report on results from a search for optically faint debris (defined as R > 20th magnitude, or smaller than 10 cm assuming an albedo of 0.175)) at geosynchronous orbit (GEO) using the 6.5-m Magellan telescope "Walter Baade" at Las Campanas Observatory in Chile. Our goal is to characterize the brightness distribution of debris to the faintest limiting magnitude possible. Our data was obtained during 6 hours of observing time during the photometric nights of 26 and 27 March 2011 with the IMACS f/2 instrument, which has a field of view (fov) of 0.5 degrees in diameter. All observations were obtained through a Sloan r filter, and calibrated by observations of Landolt standard stars. Our primary objective was to search for optically faint objects from one of the few known fragmentations at GEO: the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris with the 6.5-m telescope, followed by a survey for unknown objects on similar orbits but with different mean anomalies. To establish the bright end of the debris population, calibrated observations were acquired on the same field centers, telescope rates, and time period with a similar filter on the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will show the calibrated brightness distributions from both telescopes, and compare the observed brightness distributions with that predicted for various population models of debris of different sizes.

  5. Debris analysis workstation: from concept to reality

    NASA Astrophysics Data System (ADS)

    Spencer, David B.; Maethner, Scott R.; Shubert, Ann J.; Yates, Ken W.

    1995-06-01

    Determining the hazards from debris generating events is a design and safety consideration for a number of space systems, both currently operating and planned. To meet these and other requirements, the US Air Force Phillips Laboratory Space Debris Research Program is developing a simulation platform called the Debris Analysis Workstation (DAW) which provides an analysis capability for assessing a wide variety of debris studies. DAW integrates several component debris analysis models and data visualization tools into a single analysis platform that meets the needs for DoD space debris analysis, and is both user friendly and modular. This allows for studies to be performed expeditiously by analysts that are not debris experts. DAW has gone from concept to reality with the recent deliveries of Versions 0.1 to 0.4 to a number of customers. The current version of DAW incorporates a spacecraft break-up model, drag inclusive propagator, a collision dispersion model, a graphical user interface, and data visualization routines, which together provide capabilities to conduct missile intercept range safety analyses. Work is progressing to add new capabilities with the incorporation of additional models and improved designs. The existing tools are in their initial integrated form, but the 'glue' that will ultimately bring them together into an integrated, user-friendly system, is an object oriented language layer that is scheduled to be added in 1995. Other candidate component models that are under consideration for incorporation include additional orbital propagators, error estimation routines, dispersion models, and other breakup models. At present, DAW resides on a SUN workstation, although future versions could be tailored for other platforms, depending on the need.

  6. Loopy, Floppy and Fragmented: Debris Characteristics Matter

    NASA Astrophysics Data System (ADS)

    Parrish, J.; Burgess, H. K.

    2016-02-01

    Marine debris is a world-wide problem threatening the health and safety of marine organisms, ecosystems, and humans. Recent and ongoing research shows that risk of harm is not associated with identity, but rather with a set of specific character states, where the character state space intersection is defined by the organism of interest. For example, intersections of material, color, rigidity and size predict the likelihood of an object being ingested: plastic, clear-white, floppy objects <100cm pose higher risks to sea turtles whereas yellow-red, rigid objects <10cm pose higher risks to albatrosses. A character state space approach allows prioritization of prevention and removal of marine debris informed by risk assessments for species of interest by comparing species ranges with spatio-temporal hotspots of all debris with characteristics known to be associated with increased risk of harm, regardless of identity. With this in mind, the Coastal Observation and Seabird Survey Team (COASST) developed and tested a 20 character data collection approach to quantifying the diversity and abundance of marine debris found on beaches. Development resulted in meta-analysis of the literature and expert opinion eliciting harmful character state space. Testing included data collection on inter-rater reliability and accuracy, where the latter included 75 participants quantifying marine debris characteristics on monthly surveys of 30 beaches along the Washington and Oregon coastlines over the past year. Pilot work indicates that characters must be simply and operationally defined, states must be listed, and examples must be provided for color states. Complex characters (e.g., windage, shape) are not replicable across multiple data collectors. Although data collection takes longer than other marine debris surveys for a given amount of debris and area surveyed, volunteer rapidity and accuracy improved within 3-5 surveys. Initial feedback indicated that volunteers were willing to

  7. Overview of the space debris environment

    NASA Astrophysics Data System (ADS)

    Meshishnek, M. J.

    1995-03-01

    There is a component of the space environment that is man-made pollution, termed 'space debris' it exists at all inclinations and, primarily, at altitudes of roughly 350 km to 2000 km. The size of this debris ranges from several meters to a fraction of a micrometer in diameter, and the particle distribution follows an inverse power law, with the smaller size component far exceeding that of the larger. Debris is composed primarily of alumina from solid rocket motor exhausts, aluminum from spacecraft structures, and zinc and titanium oxides from thermal control coatings. The accepted model of the space debris environment is that of Kessler et al., a complex model that predicts the number of particles that will impact a surface as a function of altitude, inclination, solar cycle, and particle diameter, as well as their collision velocities. Recent data from LDEF has demonstrated both the accuracy and shortcomings of the Kessler model. Measured debris impactor fluxes are in good agreement with the model for ram surfaces. However, predictions of the model for other surfaces of a spacecraft are less accurate, most notably for the wake or trailing side. While the Kessler model is appropriate for long-term, average flux predictions, spatial-temporal impact fluxes measured on LDEF dramatically illustrated the presence of strong debris clouds that do not dissipate quickly in space and will encounter an orbiting spacecraft cyclically and repeatedly over its lifetime. LDEF data has also indicated the presence of debris in elliptical orbits, a fact not predicted by the Kessler model. This fact is responsible for the discrepancy between measured impact fluxes and predictions on trailing edge surfaces.

  8. Mixed debris treatment at the Idaho National Engineering Laboratory (INEL)

    SciTech Connect

    Garcia, E.C.; Porter, C.L.; Wallace, M.T.

    1993-10-01

    August 18, 1992 the Environmental Protection Agency (EPA) published the final revised treatment standards for hazardous debris, including mixed debris. (1) Whereas previous standards had been concentration based, the revised standards are performance based. Debris must be treated prior to land disposal, using specific technologies from one or more of the following families of debris treatment technologies: Extraction, destruction, or immobilization. Seventeen specific technologies with generic application are discussed in the final rule. The existing capabilities and types of debris at the INEL were scrubbed against the debris rule to determine an overall treatment strategy. Seven types of debris were identified: combustible, porous, non-porous, inherently hazardous, HEPA filters, asbestos contaminated, and reactive metals contaminated debris. With the exception of debris contaminated with reactive metals treatment can be achieved utilizing existing facilities coupled with minor modifications.

  9. Characterization of marine debris in North Carolina salt marshes.

    PubMed

    Viehman, Shay; Vander Pluym, Jenny L; Schellinger, Jennifer

    2011-12-01

    Marine debris composition, density, abundance, and accumulation were evaluated in salt marshes in Carteret County, North Carolina seasonally between 2007 and 2009. We assessed relationships between human use patterns and debris type. Wave effects on marine debris density were examined using a GIS-based forecasting tool. We assessed the influence of site wave exposure, period, and height on debris quantity. Presence and abundance of debris were related to wave exposure, vegetation type and proximity of the strata to human population and human use patterns. Plastic pieces accounted for the majority of all debris. Small debris (0-5 cm) was primarily composed of foam pieces and was frequently affiliated with natural wrack. Large debris (>100 cm) was encountered in all marsh habitat types surveyed and was primarily composed of anthropogenic wood and derelict fishing gear. Marsh cleanup efforts should be targeted to specific habitat types or debris types to minimize further damage to sensitive habitats.

  10. The social context of managing diabetes across the life span.

    PubMed

    Wiebe, Deborah J; Helgeson, Vicki; Berg, Cynthia A

    2016-10-01

    Diabetes self-management is crucial to maintaining quality of life and preventing long-term complications, and it occurs daily in the context of close interpersonal relationships. This article examines how social relationships are central to meeting the complex demands of managing Type I and Type 2 diabetes across the life span. The social context of diabetes management includes multiple resources, including family (parents, spouses), peers, romantic partners, and health care providers. We discuss how these social resources change across the life span, focusing on childhood and adolescence, emerging adulthood, and adulthood and aging. We review how diabetes both affects and is affected by key social relationships at each developmental period. Despite high variability in how the social context is conceptualized and measured across studies, findings converge on the characteristics of social relationships that facilitate or undermine diabetes management across the life span. These characteristics are consistent with both Interpersonal Theory and Self-Determination Theory, 2 organizing frameworks that we utilize to explore social behaviors that are related to diabetes management. Involvement and support from one's social partners, particularly family members, is consistently associated with good diabetes outcomes when characterized by warmth, collaboration, and acceptance. Underinvolvement and interactions characterized by conflict and criticism are consistently associated with poor diabetes outcomes. Intrusive involvement that contains elements of social control may undermine diabetes management, particularly when it impinges on self-efficacy. Implications for future research directions and for interventions that promote the effective use of the social context to improve diabetes self-management are discussed. (PsycINFO Database Record

  11. Linking social drivers of marine debris with actual marine debris on beaches.

    PubMed

    Slavin, Chris; Grage, Anna; Campbell, Marnie L

    2012-08-01

    The drivers (social) and pressures (physical) of marine debris have typically been examined separately. We redress this by using social and beach surveys at nine Tasmanian beaches, across three coastlines and within three categories of urbanisation, to examine whether people acknowledge that their actions contribute to the issue of marine debris, and whether these social drivers are reflected in the amount of marine debris detected on beaches. A large proportion (75%) of survey participants do not litter at beaches; with age, gender, income and residency influencing littering behaviour. Thus, participants recognise that littering at beaches is a problem. This social trend was reflected in the small amounts of debris that were detected. Furthermore, the amount of debris was not statistically influenced by the degree of beach urbanisation, the coastline sampled, or the proximity to beach access points. By linking social and physical aspects of this issue, management outcomes can be improved. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Debris-flow and flooding hazards associated with the December 1999 storm in coastal Venezuela and strategies for mitigation

    USGS Publications Warehouse

    Wieczorek, G.F.; Larsen, M.C.; Eaton, L.S.; Morgan, B.A.; Blair, J.L.

    2001-01-01

    Heavy rainfall from the storm of December 14-16, 1999 triggered thousands of landslides on steep slopes of the Sierra de Avila north of Caracas, Venezuela. In addition to landslides, heavy rainfall caused flooding and massive debris flows that damaged coastal communities in the State of Vargas along the Caribbean Sea. Examination of the rainfall pattern obtained from the GOES-8 satellite showed that the pattern of damage was generally consistent with the area of heaviest rainfall. Field observations of the severely affected drainage basins and historical records indicate that previous flooding and massive debris-flow events of similar magnitude to that of December 1999 have occurred throughout this region. The volume of debris-flow deposits and the large boulders that the flows transported qualifies the 1999 event amongst the largest historical rainfall-induced debris flows documented worldwide.

  13. LAD-C: A Large Area Cosmic Dust and Orbital Debris Collector on the International Space Station

    NASA Astrophysics Data System (ADS)

    Liou, J.-C.; Giovane, F.; Corsaro, R.; Stansbery, E.

    2007-01-01

    A 10 m^2 aerogel and acoustic sensor system has been under development by the U.S. Naval Research Laboratory (NRL) with main collaboration from the NASA Orbital Debris Program Office at Johnson Space Center. This Large Area Debris Collector (LAD-C) is tentatively scheduled to be deployed by the U.S. Department of Defense Space Test Program (STP) on the International Space Station (ISS) in late 2007. The system will be retrieved, after one to two years of data and sample collection, for post-flight analysis. In addition to cosmic dust and orbital debris sample return, the acoustic sensors will record impact characteristics for potential orbit determination of some of the collected samples. Source identification based on their dynamical signatures may be possible. The LAD-C science return will benefit orbital debris, cosmic dust, and satellite safety communities. This paper presents an overview of the mission objectives, basic configuration, deployment consideration, and science return of the experiment.

  14. Showing partial side view of swing span in closed position. ...

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

    Showing partial side view of swing span in closed position. The two (2) arms act as simple spans, a small amount of negative bending is accommodated by the continous top and bottom truss chords due to a continuous condition. Note the inclined end post of each of the simple spans, the operator's house, center/pivot pier and the pivotal pole-line pole placed atop of bridge. - Bridgeport Swing Span Bridge, Spanning Tennessee River, Bridgeport, Jackson County, AL

  15. Debris mitigation techniques for petawatt-class lasers in high debris environments

    NASA Astrophysics Data System (ADS)

    Schwarz, Jens; Rambo, Patrick; Kimmel, Mark; Geissel, Matthias; Robertson, Grafton; Ramsey, Marc; Headley, Daniel; Atherton, Briggs

    2010-04-01

    This paper addresses debris mitigation techniques for two different kinds of debris sources that are found in the high-energy density community. The first debris source stems from the laser-target interaction and this debris can be mitigated by avoiding a direct line of sight to the debris source (e.g. by using a sacrificial fold mirror) or by inserting a thin debris shield. Several thin film debris shields have been investigated and nitrocellulose was found to be the best suited. The second debris source originates from an external high-energy density driver or experiment. In our specific case, this is the Z accelerator, a Z-pinch machine that generates 2 MJ of x rays at 300 TW. The center section of the Z accelerator is an extremely violent environment which requires the development of novel debris mitigation approaches for backlighting with petawatt lasers. Two such approaches are presented in this paper. First, a self-closing focusing cone. In our facility, the focused beam on target is fully enclosed inside a solid focusing cone. In the first debris mitigation scenario, the last part of the cone has a “flapper” that should seal the cone when the pressure wave from the Z-pinch explosion hits it. In the second scenario, an enclosed target assembly is used, with the last part of the focusing cone connected to a “target can” which houses the laser target. The laser produced x rays for backlighting escape through a 3 mm diameter hole that is protected by an x-ray filter stack. Both techniques are discussed in detail and have been successfully tested on the Z accelerator.

  16. DETECTION OF A NEARBY HALO DEBRIS STREAM IN THE WISE AND 2MASS SURVEYS

    SciTech Connect

    Grillmair, Carl J.; Cutri, Roc; Masci, Frank J.; Conrow, Tim; Sesar, Branimir; Eisenhardt, Peter R. M.; Wright, Edward L. E-mail: roc@ipac.caltech.edu E-mail: tim@ipac.caltech.edu E-mail: peter.r.eisenhardt@jpl.nasa.gov

    2013-06-01

    Combining the Wide-Field Infrared Survey Explorer All-Sky Release with the Two Micron All Sky Survey Point Source Catalog, we detect a nearby, moderately metal-poor stellar debris stream spanning 24° across the southern sky. The stream, which we designate Alpheus, is at an estimated distance of ∼1.9 kpc. Its position, orientation, width, estimated metallicity, and, to some extent, its distance, are in approximate agreement with what one might expect of the leading tidal tail of the southern globular cluster NGC 288.

  17. A Search for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Barker, Edwin S.; Cowardin, Heather; Abercromby, Kira J.; ilha, Jiri

    2011-01-01

    Existing optical surveys for debris at geosynchronous orbit (GEO) have been conducted with meter class telescopes, which have detection limits in the range of 18th-19th magnitude. We report on a new search for optically faint debris at GEO using the 6.5-m Magellan 1 telescope Walter Baade at Las Campanas Observatory in Chile. Our goal is to go as faint as possible and characterize the brightness distribution of debris fainter than R = 20th magnitude, corresponding to a size smaller than 10 cm assuming an albedo of 0.175. We wish to compare the inferred size distribution for GEO debris with that for LEO debris. We describe results obtained during 9.4 hours of observing time during 25-27 March 2011. We used the IMACS f/2 instrument, which has a mosaic of 8 CCDs, and a field of view of 30 arc-minutes in diameter. This is the widest field of view of any instrument on either Magellan telescope. All observations were obtained through a Sloan r filter. The limiting magnitude for 5 second exposures is estimated to be fainter than 22. With this small field of view and the limited observing time, our objective was to search for optically faint objects from the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris (SSN # 25001 and 33519) with the 6.5-m telescope, followed by a survey for objects on similar orbits but with a spread in mean anomaly. To detect bright objects over a wider field of view (1.6x1.6 degrees), we observed the same field centers at the same time through a similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will describe our experiences using Magellan, a telescope never used previously for orbital debris research, and our initial results.

  18. Debris Flow Models With Vertical Redistribution

    NASA Astrophysics Data System (ADS)

    Mcelwaine, J. N.; Kowalski, J.

    2011-12-01

    The destructive power of debris flows is enormous and hence there is a need for quantitative models that can accurately describe their behavior and predict their flow paths, heights, velocities and corresponding impact pressures. The dynamics of a debris flows is effected by the pore pressure, which can be measured in experiments and in the field, but existing theories to not model this well. We introduce a new class of shallow debris flow models that includes an equation for the vertical distribution of material and show how this gives predictions of the pore pressure and can effect flow mobility. Debris flows exhibit different flow forms depending on water and solid concentration, particle size distribution and the topography of the flow path. The complex interplay between the fluid and solids of a whole range of different grain sizes leads to physical phenomena such as the development of a front with large boulders, lateral levee formation and, due to a varying fraction of particles being in suspension, an effective basal fluid pressure that can exceed the pure fluids hydrostatic pressure. Large scale debris flow data of the Illgraben torrent, Switzerland, show that a varying basal fluid pressure is characteristic for the snout of debris flows with a granular front and significantly affects basal shear stresses. A comprehensive mathematical debris flow model that explains all the observed phenomena will be extremely complicated; if it is achievable at all. However, promising approaches exist that successfully describe some of the effects in simple situations. Yet the observed basal fluid pressure data in granular front flows is not explained satisfactorily up to this point. One reason for this is that any change of the effective basal fluid pressure is associated with an internal redistribution of the solids above, and hence is caused by relative motion between the phases within the flowing body. However, this inter-component slip is usually neglected in the

  19. A Search For Optically Faint GEO Debris

    NASA Astrophysics Data System (ADS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2011-09-01

    Existing optical surveys for debris at geosynchronous orbit (GEO) have been conducted with meter class telescopes, which have detection limits in the range of 18th-19th magnitude. We report on a new search for optically faint debris at GEO using the 6.5-m Magellan telescope ‘Walter Baade’ at Las Campanas Observatory in Chile. Our goal is to go as faint as possible and characterize the brightness distribution of debris fainter than R = 20th magnitude, corresponding to a size smaller than 10 cm assuming an albedo of 0.175. We wish to compare the inferred size distribution for GEO debris with that for LEO debris. We describe preliminary results obtained during 9.4 hours of observing time during 25-27 March 2011. We used the IMACS f/2 instrument, which has a mosaic of 8 CCDs, and a field of view of 30 arc-minutes in diameter. This is the widest field of view of any instrument on either Magellan telescope. All observations were obtained through a Sloan r’ filter. The limiting magnitude for 5 second exposures is measured to be fainter tan R = 21. With this small field of view and the limited observing time, our objective was to search for optically faint objects from the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris (SSN # 25001 and 33519) with the 6.5-m telescope, followed by a survey for objects on similar orbits but with a spread in mean anomaly. To detect bright objects over a wider field of view (1.6x1.6 degrees), we observed the same field centers at the same time through a similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will describe our experiences using Magellan, a telescope never used previously for orbital debris research, and our initial results.

  20. IQ and ability across the adult life span.

    PubMed

    Baxendale, Sallie

    2011-07-01

    The experience of cognitive decline can be a potent source of anxiety and concern for many people. While an IQ consistent with estimated optimal levels or previously recorded scores may indicate no significant change in cognitive function, the patient may be accurately reporting a normal age-related deterioration in actual ability. The aim of this article is to chart the age-related changes in intellectual abilities evident on the Wechsler Adult Intelligence Scales-Fourth Edition (WAIS-IV). The norms from the WAIS-IV manual were examined to plot the age-related changes in Full-Scale IQ (FSIQ) and composite scores across the adult life span, while holding actual ability level constant across the age groups. Here we present a graphical representation of the normal cognitive developments and declines in FSIQ, Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed across the adult life span. This graphical representation provides a rational basis for the identification of atypical profiles/complaints of cognitive deterioration that may require further specialist neuropsychological evaluation. These graphs can be used to provide reassurance for healthy adults with concerns of cognitive decline and as an educative tool for their referring agencies.