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Sample records for saturn entry probe

  1. The Hera Saturn entry probe mission

    Science.gov (United States)

    Mousis, O.; Atkinson, D. H.; Spilker, T.; Venkatapathy, E.; Poncy, J.; Frampton, R.; Coustenis, A.; Reh, K.; Lebreton, J.-P.; Fletcher, L. N.; Hueso, R.; Amato, M. J.; Colaprete, A.; Ferri, F.; Stam, D.; Wurz, P.; Atreya, S.; Aslam, S.; Banfield, D. J.; Calcutt, S.; Fischer, G.; Holland, A.; Keller, C.; Kessler, E.; Leese, M.; Levacher, P.; Morse, A.; Muñoz, O.; Renard, J.-B.; Sheridan, S.; Schmider, F.-X.; Snik, F.; Waite, J. H.; Bird, M.; Cavalié, T.; Deleuil, M.; Fortney, J.; Gautier, D.; Guillot, T.; Lunine, J. I.; Marty, B.; Nixon, C.; Orton, G. S.; Sánchez-Lavega, A.

    2016-10-01

    The Hera Saturn entry probe mission is proposed as an M-class mission led by ESA with a contribution from NASA. It consists of one atmospheric probe to be sent into the atmosphere of Saturn, and a Carrier-Relay spacecraft. In this concept, the Hera probe is composed of ESA and NASA elements, and the Carrier-Relay Spacecraft is delivered by ESA. The probe is powered by batteries, and the Carrier-Relay Spacecraft is powered by solar panels and batteries. We anticipate two major subsystems to be supplied by the United States, either by direct procurement by ESA or by contribution from NASA: the solar electric power system (including solar arrays and the power management and distribution system), and the probe entry system (including the thermal protection shield and aeroshell). Hera is designed to perform in situ measurements of the chemical and isotopic compositions as well as the dynamics of Saturn's atmosphere using a single probe, with the goal of improving our understanding of the origin, formation, and evolution of Saturn, the giant planets and their satellite systems, with extrapolation to extrasolar planets. Hera's aim is to probe well into the cloud-forming region of the troposphere, below the region accessible to remote sensing, to the locations where certain cosmogenically abundant species are expected to be well mixed. By leading to an improved understanding of the processes by which giant planets formed, including the composition and properties of the local solar nebula at the time and location of giant planet formation, Hera will extend the legacy of the Galileo and Cassini missions by further addressing the creation, formation, and chemical, dynamical, and thermal evolution of the giant planets, the entire solar system including Earth and the other terrestrial planets, and formation of other planetary systems.

  2. Shock Radiation Tests for Saturn and Uranus Entry Probes

    Science.gov (United States)

    Cruden, Brett A.; Bogdanoff, David W.

    2014-01-01

    This paper describes a test series in the Electric Arc Shock Tube at NASA Ames Research Center with the objective of quantifying shock-layer radiative heating magnitudes for future probe entries into Saturn and Uranus atmospheres. Normal shock waves are measured in Hydrogen/Helium mixtures (89:11 by mole) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 km/s. No shock layer radiation is detected below 25 km/s, a finding consistent with predictions for Uranus entries. Between 25-30 km/s, radiance is quantified from the Vacuum Ultraviolet through Near Infrared, with focus on the Lyman-alpha and Balmer series lines of Hydrogen. Shock profiles are analyzed for electron number density and electronic state distribution. The shocks do not equilibrate over several cm, and distributions are demonstrated to be non-Boltzmann. Radiation data are compared to simulations of Decadal survey entries for Saturn and shown to be significantly lower than predicted with the Boltzmann radiation model.

  3. DSMC Shock Simulation of Saturn Entry Probe Conditions

    Science.gov (United States)

    Higdon, Kyle J.; Cruden, Brett A.; Brandis, Aaron M.; Liechty, Derek S.; Goldstein, David B.; Varghese, Philip L.

    2016-01-01

    This work describes the direct simulation Monte Carlo (DSMC) investigation of Saturn entry probe scenarios and the influence of non-equilibrium phenomena on Saturn entry conditions. The DSMC simulations coincide with rarefied hypersonic shock tube experiments of a hydrogen-helium mixture performed in the Electric Arc Shock Tube (EAST) at the NASA Ames Research Center. The DSMC simulations are post-processed through the NEQAIR line-by-line radiation code to compare directly to the experimental results. Improved collision cross-sections, inelastic collision parameters, and reaction rates are determined for a high temperature DSMC simulation of a 7-species H2-He mixture and an electronic excitation model is implemented in the DSMC code. Simulation results for 27.8 and 27.4 km/s shock waves are obtained at 0.2 and 0.1 Torr, respectively, and compared to measured spectra in the VUV, UV, visible, and IR ranges. These results confirm the persistence of non-equilibrium for several centimeters behind the shock and the diffusion of atomic hydrogen upstream of the shock wave. Although the magnitude of the radiance did not match experiments and an ionization inductance period was not observed in the simulations, the discrepancies indicated where improvements are needed in the DSMC and NEQAIR models.

  4. Hydrogen-Helium shock Radiation tests for Saturn Entry Probes

    Science.gov (United States)

    Cruden, Brett A.

    2016-01-01

    This paper describes the measurement of shock layer radiation in Hydrogen/Helium mixtures representative of that encountered by probes entering the Saturn atmosphere. Normal shock waves are measured in Hydrogen-Helium mixtures (89:11% by volume) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 km/s. Radiance is quantified from the Vacuum Ultraviolet through Near Infrared. An induction time of several centimeters is observed where electron density and radiance remain well below equilibrium. Radiance is observed in front of the shock layer, the characteristics of which match the expected diffusion length of Hydrogen.

  5. The Hera Entry Probe Mission to Saturn, an ESA M-class mission proposal

    Science.gov (United States)

    Mousis, O.; Atkinson, D. H.; Spilker, T.; Venkatapathy, E.; Poncy, J.; Coustenis, A.; Reh, K.

    2015-10-01

    A fundamental goal of solar system exploration is to understand the origin of the solar system, the initial stages, conditions, and processes by which the solar system formed, how the formation process was initiated, and the nature of the interstellar seed material from which the solar system was born. Key to understanding solar system formation and subsequent dynamical and chemical evolution is the origin and evolution of the giant planets and their atmospheres. Additionally, the atmospheres of the giant planets serve as laboratories to better understand the atmospheric chemistries, dynamics, processes, and climates on all planets in the solar system including Earth, offer a context and provide a ground truth for exoplanets and exoplanetary systems,and have long been thought to play a critical role in the development of potentially habitable planetary systems. Remote sensing observations are limited when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the value of in situ probe measurements is illustrated by the exploration of Jupiter, where key measurements such as noble gases abundances and the precise measurement of the helium mixing ratio have only been made available through in situ measurements by the Galileo probe. Representing the only method providing ground-truth to connect the remote sensing inferences with physical reality, in situ measurements have only been accomplished twice in the history of outer solar system exploration, via the Galileo probe for Jupiter and the Huygens probe for Titan. In situ measurements provide access to atmospheric regions that are beyond the reach of remote sensing, enabling the dynamical, chemical and aerosol-forming processes at work from the thermosphere to the troposphere below the cloud decks to be studied. A proposal for a Saturn entry probe mission named Hera was recently submitted to the European Space Agency Medium Class mission announcement of

  6. Hera - an ESA M-class Saturn Entry Probe Mission Proposal

    Science.gov (United States)

    Atkinson, D. H.; Mousis, O.; Spilker, T. R.; Venkatapathy, E.; Poncy, J.; Coustenis, A.; Reh, K. R.

    2015-12-01

    A fundamental goal of solar system exploration is to understand the origin of the solar system, the initial stages, conditions, and processes by which the solar system formed, how the formation process was initiated, and the nature of the interstellar seed material from which the solar system was born. Key to understanding solar system formation and subsequent dynamical and chemical evolution is the origin and evolution of the giant planets and their atmospheres. Additionally, the atmospheres of the giant planets serve as laboratories to better understand the atmospheric chemistries, dynamics, processes, and climates on all planets in the solar system including Earth, offer a context and provide a ground truth for exoplanets and exoplanetary systems, and have long been thought to play a critical role in the development of potentially habitable planetary systems. Remote sensing observations are limited when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the value of in situ measurements is provided by measurements of Jupiter's noble gas abundances and helium mixing ratio by the Galileo probe. In situ measurements provide direct access to atmospheric regions that are beyond the reach of remote sensing, enabling the dynamical, chemical and aerosol-forming processes at work from the thermosphere to the troposphere below the cloud decks to be studied. Studies for a newly proposed Saturn atmospheric entry probe mission named Hera is being prepared for the upcoming European Space Agency Medium Class (M5) mission announcement of opportunity. A solar powered mission, Hera will take approximately 8 years to reach Saturn and will carry instruments to measure the composition, structure, and dynamics of Saturn's atmosphere. In the context of giant planet science provided by the Galileo, Juno, and Cassini missions to Jupiter and Saturn, the Hera Saturn probe will provide critical measurements of composition

  7. Digital simulation of a communication link for Pioneer Saturn Uranus atmospheric entry probe, part 1

    Science.gov (United States)

    Hinrichs, C. A.

    1975-01-01

    A digital simulation study is presented for a candidate modulator/demodulator design in an atmospheric scintillation environment with Doppler, Doppler rate, and signal attenuation typical of the conditions of an outer planet atmospheric probe. The simulation results indicate that the mean channel error rate with and without scintillation are similar to theoretical characterizations of the link. The simulation gives information for calculating other channel statistics and generates a quantized symbol stream on magnetic tape from which error correction decoding is analyzed. Results from the magnetic tape data analyses are also included. The receiver and bit synchronizer are modeled in the simulation at the level of hardware component parameters rather than at the loop equation level and individual hardware parameters are identified. The atmospheric scintillation amplitude and phase are modeled independently. Normal and log normal amplitude processes are studied. In each case the scintillations are low pass filtered. The receiver performance is given for a range of signal to noise ratios with and without the effects of scintillation. The performance is reviewed for critical reciever parameter variations.

  8. Requirements on Atmospheric Entry of Small Probes for Several Planets: Venus, Saturn, Neptune and Uranus in Preparation for the Future ESA Cosmic Vision Missions

    Science.gov (United States)

    Tomuta, D.; Rebuffat, D.; Larranaga, J.; Erd, C.; Bavdaz, M.; Falkner, P.

    2011-02-01

    In preparation for the ESA Cosmic Vision new call for medium class missions, a set of entry probes for inner and outer planets have been preliminary investigated by ESA using its Concurrent Design Facility. These Entry Probe missions are hypothetically assumed for launching time 2020-2035. A preliminary design of the probes arrived at a mass of about 300kg. In the following, the study is focused on the entry conditions for each of the planets Venus, Saturn, Neptune and Uranus with the aim to define the conditions for the Entry and Descent System (EDS) and its required technologies. For Venus case, two scenarios where considered: one where the entry probe is released during a typical gravity assist by a large interplanetary mission and another scenario featuring a stand alone mission targeted to Venus. During the entry in Venus atmosphere (mainly composed of CO2 (96.5%) and N2 (3.5%)), the probes are subjected to maximum heat fluxes of 60MW/m2, which is highly demanding in both scenarios. For the outer planet missions, only flyby scenarios with a targeted release of the probe were considered. The entry probes for the outer planets are subjected to heat fluxes above 100MW/m2, which is even more challenging the Thermal Protection Systems (TPS) and therefore requiring the use of special high temperature protection technology to prevent the destruction during the entry. ESA efforts for future missions are directed towards the development of an European Light Ablative Material (ELAM), though used in PEP study only for the Back Cover of the Entry Module. The TPS as well as both radiative and convective heat fluxes need simulations and verification by means of ground facility experiments. Based on the lessons learned from previous mission studies (mission to a near-Earth objects c.f. Marco Polo, Deimos Sample return), an Atmospheric Mars Sample Return is now under study. For sample return missions on return to Earth, a passive re-entry capsule delivering the sample

  9. Outer planet atmospheric entry probes - An overview of technology readiness

    Science.gov (United States)

    Vojvodich, N. S.; Reynolds, R. T.; Grant, T. L.; Nachtsheim, P. R.

    1975-01-01

    Entry probe systems for characterizing, by in situ measurements, the atmospheric properties, chemical composition, and cloud structure of the planets Saturn, Uranus, and Jupiter are examined from the standpoint of unique mission requirements, associated subsystem performance, and degree of commonality of design. Past earth entry vehicles (PAET) and current planetary spacecraft (Pioneer Venus probes and Viking lander) are assessed to identify the extent of potential subsystem inheritance, as well as to establish the significant differences, in both form and function, relative to outer planet requirements. Recent research results are presented and reviewed for the most critical probe technology areas, including: science accommodation, telecommunication, and entry heating and thermal protection. Finally presented is a brief discussion of the use of decision analysis techniques for quantifying various probe heat-shield test alternatives and performance risk.

  10. Saturn PRobe Interior and aTmosphere Explorer (SPRITE)

    Science.gov (United States)

    Simon, Amy; Banfield, D.; Atkinson, D.; Atreya, S.; Brinckerhoff, W.; Colaprete, A.; Coustenis, A.; Fletcher, L.; Guillot, T.; Hofstadter, M.; hide

    2016-01-01

    The Vision and Voyages Planetary Decadal Survey identified a Saturn Probe mission as one of the high priority New Frontiers mission targets[1]. Many aspects of the Saturn system will not have been fully investigated at the end of the Cassini mission, because of limitations in its implementation and science instrumentation. Fundamental measurements of the interior structure and noble gas abundances of Saturn are needed to better constrain models of Solar System formation, as well as to provide an improved context for exoplanet systems. The SPRITE mission will fulfill the scientific goals of the Decadal Survey Saturn probe mission. It will also provide ground truth for quantities constrained by Cassini and conduct new investigations that improve our understanding of Saturn's interior structure and composition, and by proxy, those of extrasolar giant planets.

  11. In Situ Probe Science at Saturn

    Science.gov (United States)

    Atkinson, D.H.; Lunine, J.I.; Simon-Miller, A. A.; Atreya, S. K.; Brinckerhoff, W.; Colaprete, A.; Coustenis, A.; Fletcher, L. N.; Guillot, T.; Lebreton, J.-P.; hide

    2014-01-01

    A fundamental goal of solar system exploration is to understand the origin of the solar sys-tem, the initial stages, conditions, and processes by which the solar system formed, how the formation pro-cess was initiated, and the nature of the interstellar seed material from which the solar system was born. Key to understanding solar system formation and subsequent dynamical and chemical evolution is the origin and evolution of the giant planets and their atmospheres. Several theories have been put forward to explain the process of solar system formation, and the origin and evolution of the giant planets and their atmospheres. Each theory offers quantifiable predictions of the abundances of noble gases He, Ne, Ar, Kr, and Xe, and abundances of key isotopic ratios 4He3He, DH, 15N14N, 18O16O, and 13C12C. Detection of certain dis-equilibrium species, diagnostic of deeper internal pro-cesses and dynamics of the atmosphere, would also help discriminate between competing theories. Measurements of the critical abundance profiles of these key constituents into the deeper well-mixed at-mosphere must be complemented by measurements of the profiles of atmospheric structure and dynamics at high vertical resolution and also require in situ explora-tion. The atmospheres of the giant planets can also serve as laboratories to better understand the atmospheric chem-istries, dynamics, processes, and climates on all planets including Earth, and offer a context and provide a ground truth for exoplanets and exoplanetary systems. Additionally, Giant planets have long been thought to play a critical role in the development of potentially habitable planetary systems. In the context of giant planet science provided by the Galileo, Juno, and Cassini missions to Jupiter and Sat-urn, a small, relatively shallow Saturn probe capable of measuring abundances and isotopic ratios of key at-mospheric constituents, and atmospheric structure in-cluding pressures, temperatures, dynamics, and cloud

  12. Pioneer Saturn Encounter. [Pioneer 11 space probe

    Science.gov (United States)

    1979-01-01

    The Pioneer Saturn Spacecraft, which began its journey as Pioneer 11, provided the first close view of the rings of Saturn as well as its system of moons. Its payload of 11 operating instruments obtained or confirmed data about the mass, temperature, composition, radiation belts, and atmosphere of the planet and its larger satellite, Titan. It made photometric and polarization measurements of lapetus, Rhea, Dione, and Tethys, as well as discovered additional rings. Scientific highlights of the mission are summarized. Color imagery provided by the photopolarimeter is included along with illustrations of the planet's magnetic field and radiation belts.

  13. The Saturn Probe Interior and aTmosphere Explorer (SPRITE) Mission

    Science.gov (United States)

    Simon, Amy; Banfield, Donald; Atkinson, David; SPRITE Science Team

    2018-01-01

    A key question in planetary science is how the planets formed in our Solar System, and, by extension, in exoplanet systems. The abundances of the noble gases (He, Ne, Ar, Kr, Xe), heavy elements (C, N, O, S), and their isotopes provide important forensic clues as to location and time of formation in the early Solar System. Jupiter and Saturn contain most of the planetary mass in our solar system, and their chemical fingerprints will distinguish between competing models of the formation of all the planets. After the end of the Cassini mission, some of these elements have only ambiguous values above the cloud tops, while others (particularly the noble gases) have not been measured at all. Resolving this requires direct in situ measurements. The proposed NASA New Frontiers Saturn PRobe Interior and aTmosphere Explorer (SPRITE) mission delivers an instrumented entry probe from a carrier relay spacecraft that also provides context imaging. The powerful probe instrument suite is comprised of a Quadrupole Mass Spectrometer, a Tunable Laser Spectrometer, and an Atmospheric Structure Instrument including a Doppler Wind Experiment and a simple backscatter nephelometer. These instruments measure the elemental and isotopic abundances of helium, the heavier noble gases, and the major elements, as well as constraining cloud properties, 3-D atmospheric dynamics, and disequilibrium chemistry to at least 10 bars in Saturn's troposphere. In situ measurements of Saturn's atmosphere by SPRITE will provide a significantly improved context for interpreting the results from the Galileo probe, Juno, and Cassini missions. SPRITE will revolutionize our understanding of the formation and evolution of the gas giant planets, and ultimately the present-day structure of the Solar System.

  14. Heatshield for Extreme Entry Environment Technology (HEEET) for Missions to Saturn and Beyond

    Science.gov (United States)

    Ellerby, D.; Blosser, M.; Chinnapongse, R.; Fowler, M.; Gasch, M.; Hamm, K.; Kazemba, C.; Ma, J.; Milos, F.; Nishioka, O.; hide

    2015-01-01

    This poster provides an overview of the requirements, design, development and testing of the 3D Woven TPS being developed under NASAs Heatshield for Extreme Entry Environment Technology (HEEET) project. Under this current program, NASA is working to develop a Thermal Protection System (TPS) capable of surviving entry into Saturn. A primary goal of the project is to build and test an Engineering Test Unit (ETU) to establish a Technical Readiness Level (TRL) of 6 for this technology by 2017.

  15. Saturn

    CERN Document Server

    Vescia, Monique

    2017-01-01

    Saturn is one of the most surreal of all the planets in our solar system. With this intriguing curriculum-correlated book, young readers can learn just why. Saturn has many unusual features, such as rings made of ice, ammonia storms, and methane rain. Its density is less than that of water so theoretically it could float on water. The features of its many moons are sometimes even stranger. The Pioneer and Voyager missions in 1970s and 1980s offered stunning images included in the book, which will allow readers to have an armchair experience of exploring this fascinating planet.

  16. The Saturn PRobe Interior and aTmosphere Explorer (SPRITE) Mission Concept

    Science.gov (United States)

    Atkinson, David H.; Simon, Amy; Banfield, Don

    2017-04-01

    The proposed NASA New Frontiers Saturn PRobe Interior and aTmosphere Explorer (SPRITE) mission would measure the abundance of helium and the other noble gases, elemental and isotopic abundances, the clouds, dynamics, and processes within Saturn's troposphere. In situ measurements of Saturn's atmosphere by SPRITE would provide a significantly improved context for understanding the results from the Galileo Jupiter probe, and the formation and evolution of the gas giant planets, resulting in a paradigm shift in our understanding of the formation, evolution, and ultimately the present day structure of the solar system. The proposed SPRITE concept carries an instrument payload to measure Saturn's atmospheric structure, dynamics, composition, chemistry, and clouds to at least 10 bars. A Quadrupole Mass Spectrometer measures noble gases and noble gas isotopes to accuracies that exceed the Galileo probe measurements at Jupiter and allows for discrimination between competing theories of giant planet formation, evolution, and possible migration. Of particular importance are measurements of helium, key to understanding Saturn's thermal evolution. A Tunable Laser Spectrometer measures molecular abundances and isotope ratios to determine the chemical structure of Saturn's atmosphere, and disequilibrium species such as PH3 and CO which can be used to predict Saturn's deep water abundance. An Atmospheric Structure Instrument provides the pressure/temperature profile of Saturn's atmosphere to determine the altitude profile of static stability, and when combined with cloud measurements from the SPRITE Nephelometer, would elucidate processes that determine the location and structure of Saturn's multiple cloud layers. Coupled with the measurement of atmospheric vertical velocities from the Atmospheric Structure Instrument, a Doppler Wind Experiment provides a measure of the 3-dimensional dynamics of the Saturn atmosphere, including the profile of zonal winds with depth and vertical

  17. Development of a Net Flux Radiometer for the Hera Saturn Probe Mission

    Science.gov (United States)

    Aslam, Shahid; Amato, Michael; Atkinson, David; Mousis, Olivier; Nixon, Conor; Simon, Amy A.; Hera Probe Mission Team

    2016-10-01

    In situ exploration of all the giant planets in the outer solar system is an imperative and a Saturn probe is the next compelling step beyond Galileo's in situ exploration of Jupiter, the remote investigation of its interior, gravity, and magnetic fields by the Juno mission, and the Cassini spacecraft's similar orbital reconnaissance of Saturn. One such proposed future mission is "HERA: an international atmospheric probe to unveil the depths of Saturn" a nominal configuration is a combined ESA/Class-M probe mission accompanied by a launch vehicle and carrier relay spacecraft provided by NASA. One of the instruments being considered for inclusion on the probe is a Net Flux Radiometer (NFR) to unravel the vertical structure and properties of Saturn's cloud and haze layers. A NFR concept is presented that can be included in an atmospheric structure instrument suite for the Hera mission. The current design has two spectral channels i.e., a solar channel (0.4-to-5 µm) and a thermal channel (4-to-50 µm). The NFR is capable of viewing five distinct viewing angles during the descent. Non-imaging Winston cones with window and filter combinations define the spectral channels with a 5° Field-Of View (FOV). Uncooled thermopile detectors are used in each spectral channel and are read out using a custom designed radiation-hard Application Specific Integrated Circuit (ASIC).

  18. Data link relay design. [space probe with entry at Uranus

    Science.gov (United States)

    Parsons, P.

    1974-01-01

    The data link for the Ames baseline probe as applied to the MJU spacecraft specifically with an entry at Uranus is analyzed. A frequency analysis, a trajectory analysis, and a discussion of the effects on the spacecraft design by the data link are presented. The possibilities of a two-way link are considered.

  19. HUBBLE VIEWS THE GALILEO PROBE ENTRY SITE ON JUPITER

    Science.gov (United States)

    2002-01-01

    [left] - This Hubble Space Telescope image of Jupiter was taken on Oct. 5, 1995, when the giant planet was at a distance of 534 million miles (854 million kilometers) from Earth. The arrow points to the predicted site at which the Galileo Probe will enter Jupiter's atmosphere on December 7, 1995. At this latitude, the eastward winds have speeds of about 250 miles per hour (110 meters per second). The white oval to the north of the probe site drifts westward at 13 miles per hour (6 meters per second), rolling in the winds which increase sharply toward the equator. The Jupiter image was obtained with the high resolution mode of Hubble's Wide Field Planetary Camera 2 (WFPC2). Because the disk of the planet is larger than the field of view of the camera, image processing was used to combine overlapping images from three consecutive orbits to produce this full disk view of the planet. [right] - These four enlarged Hubble images of Jupiter's equatorial region show clouds sweeping across the predicted Galileo probe entry site, which is at the exact center of each frame (a small white dot has been inserted at the centered at the predicted entry site). The first image (upper left quadrant) was obtained with the WFPC2 on Oct. 4, 1995 at (18 hours UT). The second, third and fourth images (from upper right to lower right) were obtained 10, 20 and 60 hours later, respectively. The maps extend +/- 15 degrees in latitude and longitude. The distance across one of the images is about three Earth diameters (37,433 kilometers). During the intervening time between the first and fourth maps, the winds have swept the clouds 15,000 miles (24,000 kilometers) eastward. Credit: Reta Beebe (New Mexico State University), and NASA

  20. A lander mission to probe subglacial water on Saturn's moon Enceladus for life

    Science.gov (United States)

    Konstantinidis, Konstantinos; Flores Martinez, Claudio L.; Dachwald, Bernd; Ohndorf, Andreas; Dykta, Paul; Bowitz, Pascal; Rudolph, Martin; Digel, Ilya; Kowalski, Julia; Voigt, Konstantin; Förstner, Roger

    2015-01-01

    The plumes discovered by the Cassini mission emanating from the south pole of Saturn's moon Enceladus and the unique chemistry found in them have fueled speculations that Enceladus may harbor life. The presumed aquiferous fractures from which the plumes emanate would make a prime target in the search for extraterrestrial life and would be more easily accessible than the moon's subglacial ocean. A lander mission that is equipped with a subsurface maneuverable ice melting probe will be most suitable to assess the existence of life on Enceladus. A lander would have to land at a safe distance away from a plume source and melt its way to the inner wall of the fracture to analyze the plume subsurface liquids before potential biosignatures are degraded or destroyed by exposure to the vacuum of space. A possible approach for the in situ detection of biosignatures in such samples can be based on the hypothesis of universal evolutionary convergence, meaning that the independent and repeated emergence of life and certain adaptive traits is wide-spread throughout the cosmos. We thus present a hypothetical evolutionary trajectory leading towards the emergence of methanogenic chemoautotrophic microorganisms as the baseline for putative biological complexity on Enceladus. To detect their presence, several instruments are proposed that may be taken aboard a future subglacial melting probe. The "Enceladus Explorer" (EnEx) project funded by the German Space Administration (DLR), aims to develop a terrestrial navigation system for a subglacial research probe and eventually test it under realistic conditions in Antarctica using the EnEx-IceMole, a novel maneuverable subsurface ice melting probe for clean sampling and in situ analysis of ice and subglacial liquids. As part of the EnEx project, an initial concept study is foreseen for a lander mission to Enceladus to deploy the IceMole near one of the active water plumes on the moon's South-Polar Terrain, where it will search for

  1. Titan Imagery with Keck AO during and after Probe Entry

    Energy Technology Data Exchange (ETDEWEB)

    de Pater, I; Adamkovics, M; Bouchez, A H; Brown, M E; Gibbard, S G; Marchis, F; Roe, H G; Schaller, E L; Young, E

    2006-02-03

    We present adaptive optics data from the 10-m W.M. Keck telescope that were taken during the time the Huygens probe descended through Titan's atmosphere, and on the days following touch-down. The spatial resolution of the images is typically {approx}0.04-inch, or {approx}240 km on Titan (60 km/pixel). No probe entry signal was detected at levels exceeding 0.8 {micro}Jy (3-{sigma}) per pixel (0.01-inch), which although within the range of predicted flux levels, cannot constrain any models. We present data on Titan's surface, troposphere and stratosphere during the days following probe entry, when the solar phase angle varied from 0.05{sup o} up to 0.8{sup o}, with the Sun in the West. Contrary to expectation, the data often showed the East side to be brightest. Adding data obtained with Keck and Gemini over the past few years reveals that the East-West asymmetry can be explained by a combination of the solar phase angle effect together with a general preponderance of haze on Titan's East or morning hemisphere. The troposphere was characterized by quiescent weather; only a few small clouds were present near the south pole, at typical altitudes of 30-40 km. While stratospheric haze was prominent over the northern hemisphere, tropospheric haze dominated the south, from the S. pole up to latitudes of {approx} -45{sup o}. An intriguing observation is that obtained at 1.22 {micro}m, which revealed haze in the form of a collar at -60{sup o}, in contrast to the polar haze cap as usually seen. A comparison of narrow band JHK images of Titan's surface with that obtained by Cassini ISS shows a striking resemblance in small-scale features. After a decent attempt to remove the atmosphere from the images, the surface contrast between dark and bright areas may be larger at 2 {micro}m than at 1.6 and 1.3 {micro}m. If true, this could imply that the dark areas on Titan's surface are covered by a coarser grained frost than the bright areas, and/or that there

  2. Density waves in Saturn's rings probed by radio and optical occultation - Observational tests of theory

    Science.gov (United States)

    Brophy, Thomas G.; Rosen, Paul A.

    1992-01-01

    A parallel examination is conducted of Voyager radio and photopolarimeter occultation observations of the Saturn A ring's density waves. The radio instrument waves exhibit an average -90 deg offset from the dynamical phase. A warping height of about 100-m amplitude can qualtitatively reproduce this phase shift, while preserving the overall model wave shape. These results may be profoundly relevant for satellite-ring torque calculations in Saturn's rings, given the deposition of all of the net torque of the standard model in the first wavelength.

  3. Thermal net flux measurements on the Pioneer Venus entry probes

    Science.gov (United States)

    Revercomb, H. E.; Sromovsky, L. A.; Suomi, V. E.; Boese, R. W.

    1985-01-01

    Corrected thermal net (upward minus downward flux) radiation data from four Pioneer Venus probes at latitudes of 4 deg and 60 deg N, and 27 deg and 31 deg S, are presented. Comparisons of these fluxes with radiative transfer calculations were interpreted in terms of cloud properties and the global distribution of water vapor in the lower atmosphere of Venus. The presence of an as yet undetected source of IR opacity is implied by the fluxes in the upper cloud range. It was also shown that beneath the clouds the fluxes at a given altitude increase with latitude, suggesting greater IR cooling below the clouds at high latitudes and a decrease of the water vapor mixing ratios toward the equator.

  4. Miniaturized In Situ Atmospheric Probe Sampling Inlet System for Uranus or Saturn Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorleaf Research, Inc. proposes to develop a miniaturized in situ atmospheric probe sampling inlet system for measuring chemical and isotopic composition of the...

  5. Analytical theories for spacecraft entry into planetary atmospheres and design of planetary probes

    Science.gov (United States)

    Saikia, Sarag J.

    This dissertation deals with the development of analytical theories for spacecraft entry into planetary atmospheres and the design of entry spacecraft or probes for planetary science and human exploration missions. Poincare's method of small parameters is used to develop an improved approximate analytical solution for Yaroshevskii's classical planetary entry equation for the ballistic entry of a spacecraft into planetary atmospheres. From this solution, other important expressions are developed including deceleration, stagnation-point heat rate, and stagnation-point integrated heat load. The accuracy of the solution is assessed via numerical integration of the exact equations of motion. The solution is also compared to the classical solutions of Yaroshevskii and Allen and Eggers. The new second-order analytical solution is more accurate than Yaroshevskii's fifth-order solution for a range of shallow (-3 deg) to steep (up to -90 deg) entry flight path angles, thereby extending the range of applicability of the solution as compared to the classical Yaroshevskii solution, which is restricted to an entry flight path of approximately -40 deg. Universal planetary entry equations are used to develop a new analytical theory for ballistic entry of spacecraft for moderate to large initial flight path angles. Chapman's altitude variable is used as the independent variable. Poincare's method of small parameters is used to develop an analytical solution for the velocity and the flight path angle. The new solution is used to formulate key expressions for range, time-of-flight, deceleration, and aerodynamic heating parameters (e.g., stagnation-point heat rate, total stagnation-point heat load, and average heat input). The classical approximate solution of Chapman's entry equation appears as the zero-order term in the new solution. The new solution represents an order of magnitude enhancement in the accuracy compared to existing analytical solutions for moderate to large entry

  6. High temperature reflectance of hyperpure slip cast silica. [for Outer Planet Entry Probe reflective heat shields

    Science.gov (United States)

    Dillow, C. F.; Schmitt, R. J.; Blome, J. C.

    1976-01-01

    An experimental program to optically characterize hyperpure slip cast silica at elevated temperatures is described. This sintered ceramic material is being used in the development of a reflective heat shield for the Outer Planet Entry Probe. A unique high temperature integrating sphere reflectometer is described and reflectance data in the spectral range 0.23-2.3 micron are presented at temperatures up to 1427 C in air and helium environments. Kubelka-Munk (K-M) scattering and absorptance coefficients (K and S), using the Reichman extension of the K-M theory, are presented as is a unique method of obtaining K and S from the Reichman equations using only reflectance data. The hyperpure slip cast silica material was found to retain its high diffuse reflectance at temperatures up to 1204 C, with slight degradation occurring at higher temperatures.

  7. KRONOSEISMOLOGY: USING DENSITY WAVES IN SATURN'S C RING TO PROBE THE PLANET'S INTERIOR

    Energy Technology Data Exchange (ETDEWEB)

    Hedman, M. M.; Nicholson, P. D., E-mail: mmhedman@astro.cornell.edu [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14850 (United States)

    2013-07-01

    Saturn's C ring contains multiple spiral patterns that appear to be density waves driven by periodic gravitational perturbations. In other parts of Saturn's rings, such waves are generated by Lindblad resonances with Saturn's various moons, but most of the wave-like C-ring features are not situated near any strong resonance with any known moon. Using stellar occultation data obtained by the Visual and Infrared Mapping Spectrometer on board the Cassini spacecraft, we investigate the origin of six unidentified C-ring waves located between 80,900 and 87,200 km from Saturn's center. By measuring differences in the waves' phases among the different occultations, we are able to determine both the number of arms in each spiral pattern and the speeds at which these patterns rotate around the planet. We find that all six of these waves have between two and four arms and pattern speeds between 1660 Degree-Sign day{sup -1} and 1861 Degree-Sign day{sup -1}. These speeds are too large to be attributed to any satellite resonance. Instead, they are comparable to the predicted pattern speeds of waves generated by low-order normal-mode oscillations within the planet. The precise pattern speeds associated with these waves should therefore provide strong constraints on Saturn's internal structure. Furthermore, we identify multiple waves with the same number of arms and very similar pattern speeds, indicating that multiple m = 3 and m = 2 sectoral (l = m) modes may exist within the planet.

  8. A Survey of the Rapidly Emerging Field of Nanotechnology: Potential Applications for Scientific Instruments and Technologies for Atmospheric Entry Probes

    Science.gov (United States)

    Meyyappan, M.; Arnold, J. O.

    2005-01-01

    The field of Nanotechnology is well funded worldwide and innovations applicable to Solar System Exploration are emerging much more rapidly than thought possible just a few years ago. This presentation will survey recent innovations from nanotechnololgy with a focus on novel applications to atmospheric entry science and probe technology, in a fashion similar to that presented by Arnold and Venkatapathy at the previous workshop forum at Lisbon Portugal, October 6-9, 2003. Nanotechnology is a rapidly emerging field that builds systems, devices and materials from the bottom up, atom by atom, and in so doing provides them with novel and remarkable macro-scale performance. This technology has the potential to revolutionize space exploration by reducing mass and simultaneously increasing capability. Thermal, Radiation, Impact Protective Shields: Atmospheric probes and humans on long duration deep space missions involved in Solar System Exploration must safely endure 3 significant hazards: (i) atmospheric entry; (ii) radiation; and (iii) micrometeorite or debris impact. Nanostructured materials could be developed to address all three hazards with a single protective shield, which would involve much less mass than a traditional approach. The concept can be ready in time for incorporation into NASA s Crew Exploration Vehicle, and possible entry probes to fly on the Jupiter Icy Moons

  9. Black Saturn

    OpenAIRE

    Elvang, Henriette; Figueras, Pau

    2007-01-01

    Using the inverse scattering method we construct an exact stationary asymptotically flat 4+1-dimensional vacuum solution describing Black Saturn: a spherical black hole surrounded by a black ring. Angular momentum keeps the configuration in equilibrium. Black saturn reveals a number of interesting gravitational phenomena: (1) The balanced solution exhibits 2-fold continuous non-uniqueness for fixed mass and angular momentum; (2) Remarkably, the 4+1d Schwarzschild black hole is not unique, sin...

  10. Meteorite Atmospheric Entry Reproduced in Plasmatron II: Iron Oxidation State Change Probed by Xanes

    Science.gov (United States)

    Giuli, G.; Lepore, G. O.; Pittarello, L.; McKibbin, S.; Goderis, S.; Soens, B.; Bariselli, F.; Barros Dias, B. R.; Zavalan, F. L.; Magin, T.; Helber, B.; Claeys, P.

    2017-09-01

    Heating experiments are one of the approaches used to investigate those changes experienced by meteoroids during their atmospheric entry. In this work, we are going to present the preliminary results from scanning electron microscopy and X-ray Adsorption Spectroscopy, in order to quantify the oxidation state of Fe produced in the VKI Plasmatron.

  11. The Descent Imager/Spectral Radiometer (DISR) Experiment on the Huygens Entry Probe of Titan

    Science.gov (United States)

    Tomasko, M. G.; Buchhauser, D.; Bushroe, M.; Dafoe, L. E.; Doose, L. R.; Eibl, A.; Fellows, C.; Farlane, E. M.; Prout, G. M.; Pringle, M. J.; Rizk, B.; See, C.; Smith, P. H.; Tsetsenekos, K.

    2002-07-01

    The payload of the Huygens Probe into the atmosphere of Titan includes the Descent Imager/Spectral Radiometer (DISR). This instrument includes an integrated package of several optical instruments built around a silicon charge coupled device (CCD) detector, a pair of linear InGaAs array detectors, and several individual silicon detectors. Fiber optics are used extensively to feed these detectors with light collected from three frame imagers, an upward and downward-looking visible spectrometer, an upward and downward looking near-infrared spectrometer, upward and downward looking violet phtotometers, a four-channel solar aerole camera, and a sun sensor that determines the azimuth and zenith angle of the sun and measures the flux in the direct solar beam at 940 nm. An onboard optical calibration system uses a small lamp and fiber optics to track the relative sensitivity of the different optical instruments relative to each other during the seven year cruise to Titan. A 20 watt lamp and collimator are used to provide spectrally continuous illumination of the surface during the last 100 m of the descent for measurements of the reflection spectrum of the surface. The instrument contains software and hardware data compressors to permit measurements of upward and downward direct and diffuse solar flux between 350 and 1700 nm in some 330 spectral bands at approximately 2 km vertical resolution from an alititude of 160 km to the surface. The solar aureole camera measures the brightness of a 6° wide strip of the sky from 25 to 75° zenith angle near and opposite the azimuth of the sun in two passbands near 500 and 935 nm using vertical and horizontal polarizers in each spectral channel at a similar vertical resolution. The downward-looking spectrometers provide the reflection spectrum of the surface at a total of some 600 locations between 850 and 1700 nm and at more than 3000 locations between 480 and 960 nm. Some 500 individual images of the surface are expected which can

  12. Wind estimation using air data probe measurements to evaluate meteorological measurements made during Space Shuttle entries

    Science.gov (United States)

    Kelly, G. M.; Findlay, J. T.; Compton, H. R.

    1982-01-01

    Deterministic and weighted least squares methods for obtaining estimates of the horizontal winds encountered during the Shuttle entry phase are described. The estimates are based on in situ Air Data System (ADS) measurements of angle-of-attack, side-slip angle and true airspeed, in conjunction with inertial trajectory parameters obtained from the post flight trajectory reconstruction. Accuracies in the wind estimates obtained from each method are assessed using both theoretical arguments and flight results. Comparisons of derived winds with meteorological measurements taken during the first three Shuttle entries have demonstrated: (1) the usefulness of the wind estimators for evaluating meteorological measurements below 50 kft, and (2) the potential for adequate wind determinations in the absence of independent wind measurements. Comparisons of STS-3 flight-derived L/D versus predicted values from the LaRC aerodynamic data base are presented from 50 kft to touchdown. These results exemplify the importance of such determinations to enhance the ongoing Shuttle aerodynamic and aerothermodynamic research.

  13. Measurement Campaigns on Mars Entry Plasmas Using ICP Torches. Characterization by Emission Spectroscopy and Probes Techniques

    Science.gov (United States)

    Lohle, S.; Vacher, D.; Menecier, S.; Dudeck, M.; Liebhart, H.; Marynowski, T.; Herdrich, G.; Fasoulas, S.; Andre, P.

    2011-02-01

    The inductively coupled plasma torch of the Laboratoire Arc Electrique et Plasma Thermique (LAEPT) is used to generate plasma at atmospheric pressure in order to investigate the radiation behavior of different plasma flows in chemical and thermal equilibrium. In the present study, the determination of the local specific enthalpy was assessed in order to compare results of optical emission spectroscopy. The comparison is realized using an enthalpy probe of Institut für Raumfahrtsysteme (IRS) of the University of Stuttgart. However, the original approach of the enthalpy probe could not be applied, but the measured heat flux was interpreted in terms of forced convection of the hot plasma to the cooled copper surface. Following this theory, the flow temperature in thermal and chemical equilibrium can be determined which compares very well to the measured temperatures using Mach-Zehnder-Interferometry.

  14. Saturn Systems.

    Science.gov (United States)

    U Rehman, Habib; McKee, Nida A; McKee, Michael L

    2016-01-15

    Several ring systems (Saturn systems) have been studied using DFT methods that include dispersion effects. Comparison with X-ray structures are made with three systems, and the agreement is quite good. Binding enthalpies and binding free energies in dichloromethane and toluene have been computed. The effect of an encapsulated lithium cation is accessed by comparing C60 @(C6 H4 )10 and [Li@C60 @(C6 H4 )10 ](+). The [Li@C60 ](+) cation is a much better acceptor than C60 which leads to greater donor-acceptor interactions and larger charge transfer from the ring to [Li@C60 ](+). © 2015 Wiley Periodicals, Inc.

  15. Seasonal Changes In Saturn's Clouds

    Science.gov (United States)

    Carroll, Patricia A.; Yanamandra-Fisher, P. A.; Momary, T. W.; Kim, J. H.; Baines, K. H.

    2008-09-01

    Previous investigations indicate that Saturn's atmosphere consists of many hydrocarbons and trace chemical species such as methane (CH4), ammonia (NH3), and phosphine (PH3). NIR observations acquired from 1995 to 2006, equivalent to half a Saturnian year, are reduced and analyzed to study seasonal changes in the global distribution of these species in Saturn's clouds. The data was acquired from ground-based NASA/InfraRed Telescope Facility with NSFCAM and NSFCAM2 (1995-2006) and spacecraft Cassini/VIMS (2004-2006). Global cylindrical maps of reflectivitiy (or I/F) were created to extract latitudinal and pole-to-pole profiles of the planet's albedo. Since 1995, as Saturn's south pole received increasing solar insolation, the albedo maps (for wavelengths shorter than 3.0-microns) exhibit an increase in reflectivity at mid-latitudes in the southern hemisphere, decreasing towards the equator and the south pole. Our preliminary results indicate that at deeper levels in the atmosphere probed at 5.2-microns, Saturn's south pole is brightest, displaying trends opposite to those observed at shorter wavelengths. Baines et al. (2007, BAAS 38, 488) report north-south atmospheric asymmetry at 5-microns, based on Cassini/VIMS data. Data acquired from IRTF in February 2004 are consistent with Cassini/VIMS July 2004 data. We use this intersection of 2004 data sets as a benchmark to extend cloud models to the last ring plane crossing of 1995. We will apply Momary et al.'s (2007, BAAS 38, 487) cloud model to both IRTF and Cassini/VIMS data of 2004. Any difference between model and data will be quantified by adjusting the model input parameters to better match model output with observation. This project is pertinent for understanding the changing nature of Saturn;s clouds - differences in the opacity of different species, as Saturn approachs equinox in the near future. This project was supported by the NASA/Undergraduate Student Research Program (USRP) office.

  16. Huygens probe on target

    Science.gov (United States)

    1995-07-01

    In October 1997, a Titan/Centaur rocket lifting-off from Cape Canaveral will boost the spacecraft into a 6.7 year trajectory to reach Saturn. The trajectory will use two swing-bys of Venus in April 1998 and June 1999, followed by an Earth swing-by in August 1999 and a Jupiter swing-by in December 2000 to boost speed and reach Saturn in July 2004. A few months after going into orbit around Saturn, the Cassini spacecraft will release the Huygens probe for its descent through the atmosphere of Titan, the largest satellite of Saturn. The Huygens probe will measure the abundance of elements and compounds in Titan's atmosphere, the distribution of trace gases and aerosols, winds, temperature, pressure and surface state and its composition. A multi-spectral camera on the probe will provide images of the landscape of Titan. Titan is a unique planetary body in the solar system. It has an atmosphere which is primarily nitrogen. but is also rich in hydrocarbons. Due to the vast distance of the Saturnian system from the Sun, this atmosphere is at a very low temperature, thus greatly slowing down all the chemical processes. A study of this atmosphere will throw light on the development of our own atmosphere and contribute to our understanding of the origins of life on Earth. The Huygens probe is being developed by ESA with Aerospatiale (F) as the industrial prime contractor. Since the start of the programme in April 1990, very good progress has been made in design and hardware development. The entry into the Titan atmosphere will result in a very high surface temperature on the probe, generated as it decelerates due to the friction of the upper atmospheric layers. After the probe has slowed down sufficiently, a system of parachutes ensures a slow descent to the surface of Titan in approximately two and a half hours. The scientific measurements can only begin after the heat shield, which is needed to protect the probe during the high temperature entry phase, has been ejected

  17. Illustration of Saturn's Rings

    Science.gov (United States)

    2001-01-01

    This illustration shows a close-up of Saturn's rings. These rings are thought to have formed from material that was unable to form into a Moon because of tidal forces from Saturn, or from a Moon that was broken up by Saturn's tidal forces.

  18. Deep Space Network Capabilities for Receiving Weak Probe Signals

    Science.gov (United States)

    Asmar, Sami; Johnston, Doug; Preston, Robert

    2005-01-01

    Planetary probes can encounter mission scenarios where communication is not favorable during critical maneuvers or emergencies. Launch, initial acquisition, landing, trajectory corrections, safing. Communication challenges due to sub-optimum antenna pointing or transmitted power, amplitude/frequency dynamics, etc. Prevent lock-up on signal and extraction of telemetry. Examples: loss of Mars Observer, nutation of Ulysses, Galileo antenna, Mars Pathfinder and Mars Exploration Rovers Entry, Descent, and Landing, and the Cassini Saturn Orbit Insertion. A Deep Space Network capability to handle such cases has been used successfully to receive signals to characterize the scenario. This paper will describe the capability and highlight the cases of the critical communications for the Mars rovers and Saturn Orbit Insertion and preparation radio tracking of the Huygens probe at (non-DSN) radio telescopes.

  19. The Saturn System

    OpenAIRE

    Stone, E. C.; T.C. Owen

    1984-01-01

    Saturn is a giant planet surrounded by numerous rings, many satellites, and a large magnetosphere. Although the Saturn system bears a general resemblance to the Jovian system, it has many unique attributes which provide new insight into the formation and evolution of planetary systems. This introductory chapter provides an overview of the results of recent studies of the Saturn system which are described in detail in the following chapters.

  20. Saturn's outer satellite, Phoebe

    Science.gov (United States)

    1981-01-01

    Voyager 2 took this photo of Saturn's outer satellite, Phoebe, on Sept. 4, 1981, from 2.2 million kilometers (1.36 million miles) away. The photo shows that Phoebe is about 200 kilometers (120 miles) in diameter, about twice the size of Earth-based measurements; and dark, with five percent reflectivity -- much darker than any other Saturnian satellite. That, and information from Earth-based observations, indicates Phoebe is almost certainly a captured asteroid, and did not form in the original Saturn nebula as Saturn's other satellites did. Phoebe is the only Saturnian satellite that does not always show the same face to Saturn: Its orbital period is 550 days. Its rotation period (length of day), determined from Voyager 2 observations, is nine to ten hours. Other ground-based observations that indicate that Phoebe is a captured asteroid: It orbits Saturn in the ecliptic plane (the plane in which Earth and most other planets orbit the Sun), rather than in Saturn's equatorial plane as the other Saturn satellites do. And Phoebe's orbit is retrograde -- in the direction opposite to that of the other satellites. Voyager is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory.

  1. Saturn chorus latitudinal variations

    National Research Council Canada - National Science Library

    Menietti, J. D; Hospodarsky, G. B; Shprits, Y. Y; Gurnett, D. A

    2014-01-01

    The variation of propagation properties of whistler mode chorus as a function of latitude is not well known at Saturn but is important for the calculation of pitch angle diffusion and nonlinear growth of chorus...

  2. Cassini observations of Saturn's southern polar cusp

    Science.gov (United States)

    Arridge, C. S.; Jasinski, J. M.; Achilleos, N.; Bogdanova, Y. V.; Bunce, E. J.; Cowley, S. W. H.; Fazakerley, A. N.; Khurana, K. K.; Lamy, L.; Leisner, J. S.; Roussos, E.; Russell, C. T.; Zarka, P.; Coates, A. J.; Dougherty, M. K.; Jones, G. H.; Krimigis, S. M.; Krupp, N.

    2016-04-01

    The magnetospheric cusps are important sites of the coupling of a magnetosphere with the solar wind. The combination of both ground- and space-based observations at Earth has enabled considerable progress to be made in understanding the terrestrial cusp and its role in the coupling of the magnetosphere to the solar wind via the polar magnetosphere. Voyager 2 fully explored Neptune's cusp in 1989, but highly inclined orbits of the Cassini spacecraft at Saturn present the most recent opportunity to repeatedly study the polar magnetosphere of a rapidly rotating planet. In this paper we discuss observations made by Cassini during two passes through Saturn's southern polar magnetosphere. Our main findings are that (i) Cassini directly encounters the southern polar cusp with evidence for the entry of magnetosheath plasma into the cusp via magnetopause reconnection, (ii) magnetopause reconnection and entry of plasma into the cusp can occur over a range of solar wind conditions, and (iii) double cusp morphologies are consistent with the position of the cusp oscillating in phase with Saturn's global magnetospheric periodicities.

  3. Worlds Smaller than Saturn

    Science.gov (United States)

    2001-03-01

    Computerized animations show the following: (1) an artist's conception of a Saturn-like extrasolar planet; (2) star and planet motion; and (3) young stellar disk and planet formation. Footage shows the outside of the Mauna Kea Observatories in Hawaii and Geoff Marcy and Paul Butler inside while they are processing information. Then a press conference,'Worlds Smaller than Saturn', is seen. Anne Kinney, Origins Science Director, NASA Headquarters, introduces Geoff Marcy, Paul Butler, Alan Boss, and Heidi Hammel. They discuss the discovery of the two new Saturn-sized extrasolar planets that are orbiting the stars HD46375 and 79 Seti, giving details on the search technique and size distribution. They then answer questions from the press.

  4. Saturn's Rings are Fractal

    OpenAIRE

    Li, Jun; Ostoja-Starzewski, Martin

    2012-01-01

    Over the past few decades, various conjectures were advanced that Saturn's rings are Cantor-like sets, although no convincing fractal analysis of actual images has ever appeared. We focus on the images sent by the Cassini spacecraft mission: slide #42 "Mapping Clumps in Saturn's Rings" and slide #54 "Scattered Sunshine". Using the box-counting method, we determine the fractal dimension of rings seen here (and in several other images from the same source) to be consistently about 1.6~1.7. This...

  5. Cloud forms on Saturn

    Science.gov (United States)

    Burke, J. J.; Gehrels, T.; Strickland, R. N.

    1980-01-01

    The imaging photopolarimeter on Pioneer Saturn provided spin-scan images of Saturn's cloudtops. Only subtle departures from a uniform brightness distribution were apparent, except in the polar regions. At other latitudes the images show only a few features; they primarily support the conclusion that the visible atmosphere is a deep haze. Belts and zones are seen, and some detail in a zone near + or - 60 deg latitude. The North Equatorial Belt consists of two dark belts separated by a brighter zone exhibiting longitudinal structure.

  6. "Saturn" remains in orbit

    Directory of Open Access Journals (Sweden)

    Glushechenko E. N.

    2013-05-01

    Full Text Available The article is dedicated to scientific and production enterprise "Saturn" — since its foundation up to the present day. The authors describe the determining stages of its development and its team’s scientific and technological achievements over the 45-year history of the enterprise.

  7. Rings around Saturn.

    Science.gov (United States)

    Preskill, Hallie; And Others

    1994-01-01

    Describes difficulties of Saint Paul's Saturn School of Tomorrow from planner, implementor, and evaluator viewpoints. The plan for a citywide, ungraded, downtown middle school called for an extended school year and the latest technology in a completely redesigned building with 4 teachers, 4 interns, and 162 students. Teachers were overworked, test…

  8. Saturn Nebula (NGC 7009)

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    A planetary nebula in the constellation Aquarius, position RA 21 h 04.4 m, dec. -11° 22'. It measures 25'' and shines with a greenish hue. It is of eighth magnitude and for a planetary nebula has a high surface brightness. Two small lobes on either side give it the appearance of the planet Saturn....

  9. Saturn Ring Seismology: Interpreting the Seismogram

    Science.gov (United States)

    Marley, Mark Scott

    2013-01-01

    Marley (1990) and Marley and Porco (1993) proposed that f-mode oscillations of Saturn could excite resonant density and bending waves in the inner C-ring. They hypothesized that certain wave features discovered by Rosen et al. (1991) that were not associated with known satellite resonances could be the result of such resonant interactions with the planetary oscillation modes. They also predicted that if this was the case the waves would be found to be density (and not bending) waves by Cassini and predicted the azimuthal wave number of the C-ring waves m. Employing Cassini VIMS stellar occultation data Hedman and Nicholson (2013) have now confirmed the predictions and demonstrated that at least some of the C-ring features identified by Rosen et al. are indeed likely caused by resonant oscillation modes of Saturn. Given this context we have taken a fresh look at the Saturn ring seismology. First we propose that an apparent bending wave denoted 'j' by Rosen may be a second order outer vertical resonance with the l=3, m=2 f-mode of Saturn and discuss the locations of other plausible second order resonances in the rings. Since only a handful of ring resonances have been identified, measuring even one or two additional planetary mode frequencies would substantially assist the process of inverting mode frequencies to constrain Saturn interior's structure. Using the available mode frequencies, modern inversion technique employed in stellar seismology, and a recent set of Saturn interior models we provide an initial estimation of what available mode frequencies are telling us about the interior structure of the planet. Since the f-modes are confined relatively closely to the planetary surface, most of the observed modes probe only the outermost layers of the planet that are already comparatively well understood. However the l = 2 mode does probe relatively deeply into the planet and we will discuss the potential the measurement of this mode frequency has for placing new

  10. Saturn's Spectacular Ring System

    Science.gov (United States)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Saturn's beautiful rings have fascinated astronomers since they were first observed by Galileo in 1610. The main rings consist of solid particles mostly in the 1 cm - 10 m range, composed primarily of water ice. The ring disk is exceptionally thin - the typical local thickness of the bright rings is tens of meters, whereas the diameter of the main rings is 250,000 km! The main rings exhibit substantial radial variations "ringlets", many of which are actively maintained via gravitational perturbations from Saturn's moons. Exterior to the main rings lie tenuous dust rings, which have little mass but occupy a very large volume of space. This seminar will emphasize the physics of ring-moon interactions, recent advances in our understanding of various aspects of the rings obtained from observations taken during 1995 when the rings appeared edge-on to the Earth and then to the Sun, and observations in subsequent years from HST.

  11. Saturn's largest ring.

    Science.gov (United States)

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus.

  12. Neptune Polar Orbiter with Probes

    Science.gov (United States)

    Bienstock, Bernard; Atkinson, David; Baines, Kevin; Mahaffy, Paul; Steffes, Paul; Atreya, Sushil; Stern, Alan; Wright, Michael; Willenberg, Harvey; Smith, David; hide

    2005-01-01

    The giant planets of the outer solar system divide into two distinct classes: the gas giants Jupiter and Saturn, which consist mainly of hydrogen and helium; and the ice giants Uranus and Neptune, which are believed to contain significant amounts of the heavier elements oxygen, nitrogen, and carbon and sulfur. Detailed comparisons of the internal structures and compositions of the gas giants with those of the ice giants will yield valuable insights into the processes that formed the solar system and, perhaps, other planetary systems. By 2012, Galileo, Cassini and possibly a Jupiter Orbiter mission with microwave radiometers, Juno, in the New Frontiers program, will have yielded significant information on the chemical and physical properties of Jupiter and Saturn. A Neptune Orbiter with Probes (NOP) mission would deliver the corresponding key data for an ice giant planet. Such a mission would ideally study the deep Neptune atmosphere to pressures approaching and possibly exceeding 1000 bars, as well as the rings, Triton, Nereid, and Neptune s other icy satellites. A potential source of power would be nuclear electric propulsion (NEP). Such an ambitious mission requires that a number of technical issues be investigated, however, including: (1) atmospheric entry probe thermal protection system (TPS) design, (2) probe structural design including seals, windows, penetrations and pressure vessel, (3) digital, RF subsystem, and overall communication link design for long term operation in the very extreme environment of Neptune's deep atmosphere, (4) trajectory design allowing probe release on a trajectory to impact Neptune while allowing the spacecraft to achieve a polar orbit of Neptune, (5) and finally the suite of science instruments enabled by the probe technology to explore the depths of the Neptune atmosphere. Another driving factor in the design of the Orbiter and Probes is the necessity to maintain a fully operational flight system during the lengthy transit time

  13. The Small Next-generation Atmospheric Probe (SNAP) for Exploration of the Ice Giants - A PSDS3 Mission Concept Study

    Science.gov (United States)

    Atkinson, David H.; Sayanagi, Kunio M.; Dillman, robert A.; Hope, Drew J.; Li, Jing; Saikia, Sarag J.; Simon, Amy A.; Spilker, Thomas R.; Wong, Michael H.

    2017-10-01

    The Small Next-generation Atmospheric Probe (SNAP) mission concept was selected under the NASA Planetary Science Deep Space Small Satellite (PSDS3) call. Envisioned as a secondary probe on a future ice giant flagship mission nominally comprising an orbiter and primary probe, SNAP would provide measurements of spatially variable atmospheric properties such as the abundances of key volatiles, the distribution of clouds and cloud-forming chemical species, thermal stratification and stability of the atmosphere, and the vertical profile of zonal wind speeds at the probe descent location. In addition to Uranus and Neptune, the SNAP design is also a viable Saturn entry probe.The SNAP mission concept would comprise a 30-kg entry probe with a diameter of ~0.5m (less than half the size of the Galileo probe) that could descend through at least 5-bars. The baseline payload would include an atmospheric structure instrument to measure the altitude profile of atmospheric pressure and temperature, an atmospheric composition sensor, and an ultrastable oscillator to enable radio science measurements including Doppler wind tracking. An identical ultrastable oscillator would be carried within the probe relay link receiver hardware on the carrier spacecraft. All probe data, including pre-entry and entry calibration and housekeeping data, entry accelerometry, and descent pressures, temperatures, composition, and zonal winds, would be returned to Earth by utilizing the carrier as a relay station.The in-situ atmospheric investigations enabled by SNAP would lead to an improved understanding of the chemical and physical processes that shape giant planet atmospheres, which in turn would shed light on the formation and evolution processes of the giant planets and the Solar System. The composition measurements would also provide chemical evidence addressing theories of planetary migration, thereby improving the understanding of the giant planets' role in promoting a habitable planetary systems.

  14. Outer planet probe navigation. [considering Pioneer space missions

    Science.gov (United States)

    Friedman, L.

    1974-01-01

    A series of navigation studies in conjunction with outer planet Pioneer missions are reformed to determine navigation requirements and measurement systems in order to target probes. Some particular cases are established where optical navigation is important and some cases where radio alone navigation is suffucient. Considered are a direct Saturn mission, a Saturn Uranus mission, a Jupiter Uranus mission, and a Titan probe mission.

  15. Flight characteristics of probes in the atmospheres of Mars, Venus, and the outer planets

    Science.gov (United States)

    Intrieri, P. F.; Derose, C. E.; Kirk, D. B.

    1976-01-01

    Density, pressure, and temperature profiles of an unknown planetary atmosphere can be obtained from the high-speed entry of a probe provided the aerodynamic characteristics of the probe in this atmosphere are accurately known. An investigation of the effect of gas composition on probe aerodynamics has been conducted in the Ames Hypersonic Free Flight Facility by gun launching small-scale models into atmospheres representative of Mars, Venus, Jupiter, and Saturn. Aerodynamic data at conditions matching the velocity and Reynolds number at a number of points on the Viking trajectory (Mars) were obtained in both air and carbon dioxide and significant differences were noted. Aerodynamic data are also presented from tests in hydrogen and hydrogen-helium mixtures, gases which characterize the atmospheres of the outer planets.

  16. Saturn: atmosphere, ionosphere, and magnetosphere.

    Science.gov (United States)

    Gombosi, Tamas I; Ingersoll, Andrew P

    2010-03-19

    The Cassini spacecraft has been in orbit around Saturn since 30 June 2004, yielding a wealth of data about the Saturn system. This review focuses on the atmosphere and magnetosphere and briefly outlines the state of our knowledge after the Cassini prime mission. The mission has addressed a host of fundamental questions: What processes control the physics, chemistry, and dynamics of the atmosphere? Where does the magnetospheric plasma come from? What are the physical processes coupling the ionosphere and magnetosphere? And, what are the rotation rates of Saturn's atmosphere and magnetosphere?

  17. Saturn Ring Observer

    Science.gov (United States)

    Spilker, T. R.

    2001-01-01

    Answering fundamental questions about ring particle characteristics, and individual and group behavior, appears to require close-proximity (a few km) observations. Saturn's magnificent example of a ring system offers a full range of particle sizes, densities, and behaviors for study, so it is a natural choice for such detailed investigation. Missions implementing these observations require post-approach Delta(V) of approximately 10 km/s or more, so past mission concepts called upon Nuclear Electric Propulsion. The concept described here reduces the propulsive Delta(V) requirement to as little as 3.5 km/s, difficult but not impossible for high-performance chemical propulsion systems. Additional information is contained in the original extended abstract.

  18. Saturn's outer satellite - Phoebe

    Science.gov (United States)

    1999-01-01

    Voyager 2 took these images of Saturn's outer satellite Phoebe, on Sept. 4, 1981, from 2.2 million kilometers (1.36 million miles)away. This pair shows two different hemispheres of the satellite. The left image shows a bright mountain on the upper right edge reflecting the light of the setting sun. This mountain is possibly the central peak of a large impact crater taking up most of the upper right quadrant of Phoebe in this view. The right images shows a hemisphere with an intrinsically bright spot in the top portion of the image as well as the ridges appearing bright in the sunset light of the lower right. These images were processed by the Multimission Image Processing Laboratory of the Jet Propulsion Laboratory. The Jet Propulsion Laboratory manages the Voyager Project for NASA's Office of Space Science and Applications.

  19. Mass of Saturn's A ring

    Science.gov (United States)

    Horn, L. J.; Russell, C. T.

    1993-01-01

    The mass of Saturn's A ring is reestimated using the behavior of spiral density waves embedded in the ring. The Voyager photopolarimeter (PPS) observed the star delta-Scorpii as it was occulted by Saturn's rings during the Voyager 2 flyby of Saturn in 1981 producing a radial profile of the rings. We examined forty spiral density waves in the Voyager PPS data of the A ring including 10 weaker waves that have not been previously analyzed by means of an autoregressive power spectral technique called Burg. The strengths of this new method for ring studies are that weaker, less extended waves are easily detected and characterized. This method is also the first one which does not require precise knowledge of the resonance location and phase of the wave in order to calculate the surface mass density. Uncertainties of up to 3 km are present in the currently available radial scales for Saturn's rings.

  20. Cassini at Saturn Huygens results

    CERN Document Server

    Harland, David M

    2007-01-01

    "Cassini At Saturn - Huygens Results" will bring the story of the Cassini-Huygens mission and their joint exploration of the Saturnian system right up to date. Cassini is due to enter orbit around Saturn on the 1 July 2004 and the author will have 8 months of scientific data available for review, including the most spectacular images of Saturn, its rings and satellites ever obtained by a space mission. As the Cassini spacecraft approached its destination in spring 2004, the quality of the images already being returned by the spacecraft clearly demonstrate the spectacular nature of the close-range views that will be obtained. The book will contain a 16-page colour section, comprising a carefully chosen selection of the most stunning images to be released during the spacecraft's initial period of operation. The Huygens craft will be released by Cassini in December 2004 and is due to parachute through the clouds of Saturn's largest moon, Titan, in January 2005.

  1. Resin-Impregnated Carbon Ablator: A New Ablative Material for Hyperbolic Entry Speeds

    Science.gov (United States)

    Esper, Jaime; Lengowski, Michael

    2012-01-01

    Ablative materials are required to protect a space vehicle from the extreme temperatures encountered during the most demanding (hyperbolic) atmospheric entry velocities, either for probes launched toward other celestial bodies, or coming back to Earth from deep space missions. To that effect, the resin-impregnated carbon ablator (RICA) is a high-temperature carbon/phenolic ablative thermal protection system (TPS) material designed to use modern and commercially viable components in its manufacture. Heritage carbon/phenolic ablators intended for this use rely on materials that are no longer in production (i.e., Galileo, Pioneer Venus); hence the development of alternatives such as RICA is necessary for future NASA planetary entry and Earth re-entry missions. RICA s capabilities were initially measured in air for Earth re-entry applications, where it was exposed to a heat flux of 14 MW/sq m for 22 seconds. Methane tests were also carried out for potential application in Saturn s moon Titan, with a nominal heat flux of 1.4 MW/sq m for up to 478 seconds. Three slightly different material formulations were manufactured and subsequently tested at the Plasma Wind Tunnel of the University of Stuttgart in Germany (PWK1) in the summer and fall of 2010. The TPS integrity was well preserved in most cases, and results show great promise.

  2. Black Saturn with dipole ring

    OpenAIRE

    Yazadjiev, Stoytcho

    2007-01-01

    We present a new stationary, asymptotically flat solution of 5D Einstein-Maxwell gravity describing a Saturn-like black object: a rotating black hole surrounded by a rotating dipole black ring. The solution is generated by combining the vacuum black Saturn solution and the vacuum black ring solution with appropriately chosen parameters. Some basic properties of the solution are analyzed and the basic quantities are calculated.

  3. Saturn's Helium Abundance from Cassini CIRS and RSS Data

    Science.gov (United States)

    Achterberg, Richard K.; Schinder, Paul J.; Flasar, F. Michael

    2016-10-01

    The ratio of helium to hydrogen in Saturn's atmosphere provides an important constraint on models of Saturn's formation and evolution, but has been poorly constrained by available data. Measurements combining Voyager infrared and radio data [1] gave a He/H2 mole ratio of 0.034 ± 0.024, far below the protosolar value and requiring either significant helium loss or sequestration in the interior. Prompted by discrepancies between the Voyager infrared/radio and Galileo probe measurements of helium on Jupiter, Conrath and Gautier [2] reevaluated the helium abundance on Saturn from Voyager infrared data only, obtaining a He/H2 mole ratio of 0.135 ± 0.025, inconsistent with the previous results. Because of this discrepancy, estimating Saturn's atmospheric helium abundance has been a major goal of the Cassini mission.We are estimating the He/H2 mole ratio in Saturn's atmosphere using a combination of data from the Cassini Radio Science Subsystem (RSS) and Composite InfraRed Spectrometer (CIRS). Radio occultations, in which a carrier signal is observed as Cassini passed behind Saturn as seen from antennas on Earth, give a vertical profile of atmospheric refractivity, which can be converted to temperature as a function of pressure assuming a mean molecular weight. The assumed molecular weight is adjusted until synthetic thermal infrared spectra match spectra observed by CIRS at the same latitude and time. Preliminary results from a set of eleven near-equatorial occultations taken in 2005 give He/H2 mole ratios varying between ~0.060 and 0.085.[1] Conrath, B. J., et al., 1984, Ap. J., 282:807-815[2] Conrath, B. J. and D. Gautier, 2000, Icarus, 144:124-134

  4. Identification of Saturn-driven bending waves in Saturn's inner C ring

    Science.gov (United States)

    French, Richard; Colwell, Joshua; Nicholson, Phillip; Marouf, Essam; McGhee-French, Colleen; Hedman, Matthew

    2016-07-01

    Saturn's C ring is host to more than a dozen wavelike features whose detailed nature has been a mystery since their discovery in high-resolution Voyager radio occultations of the rings. Rosen et al. (1991 Icarus 93, 25) enumerated several of these, and the list was augmented by Baillié et al. (2011 Icarus 216, 292), based on a detailed analysis of Cassini UVIS stellar occultation profiles. Recently, Hedman and Nicholson (2013 Astron. J. 146, 12; 2014 MNRAS 444, 1369) were able to identify the wavenumbers and pattern speeds for several of the waves. They showed that several Outer Lindblad Resonances (OLR) density waves had properties that were in general quite consistent with the predictions of Marley and Porco (1993 Icarus, 106, 508) and Marley (2014 Icarus, 234, 194) that Saturn's acoustic oscillations had pattern speeds with corresponding resonance radii in the C ring. Hedman and Nicholson also identified a set of Inner Lindblad Resonance density waves with pattern speeds very close to Saturn's rotation period. Finally, French et al. (2016 Icarus, in press) identified an inward-propagating m=2 wave in the Maxwell Ringlet. These new identifications ushered in the field of Kronoseismology -- the probing of the nature of Saturn's interior from the analysis of Saturn-driven waves in the rings. Here, we report the identification of six additional wave features, all in the inner C ring, from Cassini occultation measurements. Two of the waves are OLRs: Baillié feature #5 (B1 = W76.022 (i.e., r=76022 km)) with wavenumber m=-9, and Baillié #9 (B9 = W76.435) with m=-2. The first of these is presumably Saturn-driven, but of unknown origin; W76.435 fits very nicely in the pattern predicted by Marley (2014) for an m=l-2, q=2 internal oscillation. We also report the identification of a new class of Saturn-driven waves: B1 (W74.666), B3 (W74.936), B4 (W74.941), and B6 (W76.234) are all bending waves at Outer Vertical Resonances (OVR) with wavenumbers between m=-4 and m=-9

  5. Saturn and How to Observe it

    CERN Document Server

    Benton, Julius L

    2005-01-01

    Saturn is the second largest planet in the solar system, and the only one with a spectacular ring system easily visible from Earth. Julius Benton's Saturn and How to Observe It provides a compendium of the latest information, amateur and professional images of Saturn. These images are followed by advice on how to observe Saturn using a variety of telescope apertures, color filters and magnifications. This text is a goldmine of information for all levels of amateur observers, from the beginner to the highly experienced. Brought to life by crisp color photographs, Saturn and How to Observe It is a modern comprehensive review of Saturn as a planet and its magnificent ring system. The book includes some of the latest detailed theories and physical descriptions of Saturn and its satellites. The techniques for observing Saturn are outlined in this book, giving the reader a thorough explanation of what they are viewing.

  6. Auroral Morphologies of Jupiter and Saturn

    OpenAIRE

    Grodent, Denis

    2015-01-01

    We review the principal differences and similarities of the morphologies of Jupiter and Saturn's auroral emissions. We then show some examples of UV images that are expected to be acquired with Cassini UVIS at Saturn and Juno UVS at Jupiter.

  7. 7. Saturne study meeting; Septiemes journees d`etudes saturne

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This Saturne workshop has welcomed 120 scientists. 3 sessions have been organized: accelerators, physics and miscellaneous. The most recent experiments realized or scheduled at Saturne have been presented and the discussions which followed showed the high scientific interest taken in that equipment and made the participants regret its definitive closing down. Presentations by european teams about existent equipment, machines under construction or new projects opened the way to new perspectives. A lot of contributions were dedicated to the realization of high intensity particle beams and to the applications of accelerators. (A.C.)

  8. Cassini observations of ionospheric plasma in Saturn's magnetotail lobes.

    Science.gov (United States)

    Felici, M; Arridge, C S; Coates, A J; Badman, S V; Dougherty, M K; Jackman, C M; Kurth, W S; Melin, H; Mitchell, D G; Reisenfeld, D B; Sergis, N

    2016-01-01

    Studies of Saturn's magnetosphere with the Cassini mission have established the importance of Enceladus as the dominant mass source for Saturn's magnetosphere. It is well known that the ionosphere is an important mass source at Earth during periods of intense geomagnetic activity, but lesser attention has been dedicated to study the ionospheric mass source at Saturn. In this paper we describe a case study of data from Saturn's magnetotail, when Cassini was located at ≃ 2200 h Saturn local time at 36  R S from Saturn. During several entries into the magnetotail lobe, tailward flowing cold electrons and a cold ion beam were observed directly adjacent to the plasma sheet and extending deeper into the lobe. The electrons and ions appear to be dispersed, dropping to lower energies with time. The composition of both the plasma sheet and lobe ions show very low fluxes (sometimes zero within measurement error) of water group ions. The magnetic field has a swept-forward configuration which is atypical for this region, and the total magnetic field strength is larger than expected at this distance from the planet. Ultraviolet auroral observations show a dawn brightening, and upstream heliospheric models suggest that the magnetosphere is being compressed by a region of high solar wind ram pressure. We interpret this event as the observation of ionospheric outflow in Saturn's magnetotail. We estimate a number flux between (2.95 ± 0.43) × 10 9 and (1.43 ± 0.21) × 10 10  cm -2  s -1 , 1 or about 2 orders of magnitude larger than suggested by steady state MHD models, with a mass source between 1.4 ×10 2 and 1.1 ×10 3  kg/s. After considering several configurations for the active atmospheric regions, we consider as most probable the main auroral oval, with associated mass source between 49.7 ±13.4 and 239.8 ±64.8 kg/s for an average auroral oval, and 10 ±4 and 49 ±23 kg/s for the specific auroral oval morphology found during this event. It is not clear how

  9. Saturn's Misbegotten Moonlets

    Science.gov (United States)

    Spitale, Joseph N.

    2017-06-01

    Saturn's rings are interspersed with numerous narrow (tens of km wide) gaps. Two of the largest of these gaps -- Encke and Keeler -- contain satellites -- Pan and Daphnis -- that maintain their respective gaps via the classical Goldreich/Tremaine-style shepherding mechanism wherein angular momentum is transferred across the essentially empty gap via torques acting between the satellites and the ring. Other prominent gaps are shepherded by resonances with external satellites or planetary modes: Mimas shepherds the outer edge of the B ring, clearing the inner part of the Cassini Division, Titan shepherds the Columbo ringlet / gap, and the Maxwell ringlet / gap is likely maintained by a resonance with a planetary mode. Prior to Cassini, it was expected that all of the gaps would be shepherded in a similar manner.However, many small gaps do not correspond with known resonances, and no satellites were spotted within those gaps during Cassini's prime and extended mission. To address this issue, a series of Cassini imaging observations were planned to examine 11 gaps in the C ring and Cassini division at a resolution and longitudinal coverage sufficient to either discover the shepherds or rule out their presence. The survey discovered no embedded satellites. Longitudinal coverage was incomplete, but within longitudes covered by the survey, satellites are ruled out to sizes in the 100-m range, far too small keep the observed gaps open. It is possible (about even odds) that there could be a larger satellite residing at a longitude not covered in the survey, but the probability that the survey was unfortunate enough to miss significant satellites in all 11 gaps is exceedingly small (~0.002%). Moreover, these gaps appear in earlier imaging sequences, with some high-resolution coverage, so the true probability is smaller yet. Therefore, a new theory is likely needed to explain the presence of the gaps.

  10. An Explanation for Saturn's Hexagon

    Science.gov (United States)

    Kohler, Susanna

    2015-08-01

    For over three decades, weve been gathering observations of the mysterious hexagonal cloud pattern encircling Saturns north pole. Now, researchers believe they have a model that can better explain its formation.Fascinating GeometrySaturns northern Hexagon is a cloud band circling Saturns north pole at 78 N, first observed by the Voyager flybys in 198081. This remarkable pattern has now persisted for more than a Saturn year (29.5 Earth years).Eight frames demonstrating the motion within Saturns Hexagon. Click to watch the animation! The view is from a reference frame rotating with Saturn. [NASA/JPL-Caltech/SSI/Hampton University]Observations by Voyager and, more recently, Cassini have helped to identify many key characteristics of this bizarre structure. Two interesting things weve learned are:The Hexagon is associated with an eastward zonal jet moving at more than 200 mph.The cause of the Hexagon is believed to be a jet stream, similar to the ones that we experience on Earth. The path of the jet itself appears to follow the hexagons outline.The Hexagon rotates at roughly the same rate as Saturns overall rotation.While we observe individual storms and cloud patterns moving at different speeds within the Hexagon, the vertices of the Hexagon move at almost exactly the same rotational speed as that of Saturn itself.Attempts to model the formation of the Hexagon with a jet stream have yet to fully reproduce all of the observed features and behavior. But now, a team led by Ral Morales-Juberas of the New Mexico Institute of Mining and Technology believes they have created a model that better matches what we see.Simulating a Meandering JetThe team ran a series of simulations of an eastward, Gaussian-profile jet around Saturns pole. They introduced small perturbations to the jet and demonstrated that, as a result of the perturbations, the jet can meander into a hexagonal shape. With the initial conditions of the teams model, the meandering jet is able to settle into a

  11. An Infrared View of Saturn

    Science.gov (United States)

    1998-01-01

    In honor of NASA Hubble Space Telescope's eighth anniversary, we have gift wrapped Saturn in vivid colors. Actually, this image is courtesy of the new Near Infrared Camera and Multi-Object Spectrometer (NICMOS), which has taken its first peek at Saturn. The false-color image - taken Jan. 4, 1998 - shows the planet's reflected infrared light. This view provides detailed information on the clouds and hazes in Saturn's atmosphere.The blue colors indicate a clear atmosphere down to a main cloud layer. Different shadings of blue indicate variations in the cloud particles, in size or chemical composition. The cloud particles are believed to be ammonia ice crystals. Most of the northern hemisphere that is visible above the rings is relatively clear. The dark region around the south pole at the bottom indicates a big hole in the main cloud layer.The green and yellow colors indicate a haze above the main cloud layer. The haze is thin where the colors are green but thick where they are yellow. Most of the southern hemisphere (the lower part of Saturn) is quite hazy. These layers are aligned with latitude lines, due to Saturn's east-west winds.The red and orange colors indicate clouds reaching up high into the atmosphere. Red clouds are even higher than orange clouds. The densest regions of two storms near Saturn's equator appear white. On Earth, the storms with the highest clouds are also found in tropical latitudes. The smaller storm on the left is about as large as the Earth, and larger storms have been recorded on Saturn in 1990 and 1994.The rings, made up of chunks of ice, are as white as images of ice taken in visible light. However, in the infrared, water absorption causes various colorations. The most obvious is the brown color of the innermost ring. The rings cast their shadow onto Saturn. The bright line seen within this shadow is sunlight shining through the Cassini Division, the separation between the two bright rings. It is best observed on the left side, just

  12. The Voyager encounters with Saturn

    Science.gov (United States)

    Stone, E. C.

    1984-04-01

    In 1972, the Voyager Program was undertaken by NASA as a major step in the exploration of the outer solar system. Recently the objectives of this program have been extended to include an investigation of Uranus and possibly Neptune. In connection with the present investigation, a brief description of the Voyager spacecraft is presented and an overview of the scientific results from the Saturn encounters is provided. Two essentially identical Voyager spacecraft were launched in 1977 toward encounters with the Jovian and Saturnian planetary systems. The Voyager 1 trajectory at Saturn was chosen to provide a close encounter with Titan, a planet-sized satellite with an atmosphere, and to provide an optimum geometry for dual-frequency radio occultation studies of Saturn's rings. The Voyager 2 trajectory provided improved viewing of the rings.

  13. Three-dimensional modeling of lightning-induced electromagnetic pulses on Venus, Jupiter, and Saturn

    Science.gov (United States)

    Pérez-Invernón, F. J.; Luque, A.; Gordillo-Vázquez, F. J.

    2017-07-01

    While lightning activity in Venus is still controversial, its existence in Jupiter and Saturn was first detected by the Voyager missions and later on confirmed by Cassini and New Horizons optical recordings in the case of Jupiter, and recently by Cassini on Saturn in 2009. Based on a recently developed 3-D model, we investigate the influence of lightning-emitted electromagnetic pulses on the upper atmosphere of Venus, Saturn, and Jupiter. We explore how different lightning properties such as total energy released and orientation (vertical, horizontal, and oblique) can produce mesospheric transient optical emissions of different shapes, sizes, and intensities. Moreover, we show that the relatively strong background magnetic field of Saturn can enhance the lightning-induced quasi-electrostatic and inductive electric field components above 1000 km of altitude producing stronger transient optical emissions that could be detected from orbital probes.

  14. Encouragement from Jupiter for Europe's Titan Probe

    Science.gov (United States)

    1996-04-01

    remaining after searching reviews of the Probe's design and readiness. Shock tests will check that Huygens is not harmed by the firing of pyrotechnic devices used to release the protective shell and the parachutes, after the Probe's incandescent entry into Titan's atmosphere. In addition, the so-called Titan Test will be repeated. This subjects the Probe to a simulation of the very cold atmosphere of the target moon. A previous test showed some components in Huygens approaching the lower limit of acceptable temperatures. The repeated test will verify that subsequent minor modifications have succeeded in reducing effect of the chilling. Background facts about the Cassini/Huygens mission Huygens is a medium-sized mission of ESA's Horizon 2000 programme for space science, and a contribution to the joint NASA-ESA Cassini mission. Christiaan Huygens discovered Saturn's moon Titan in 1655, and the mission named after him aims to deliver a 343-kilogram Probe to Titan and carry a package of scientific instruments through the atmosphere. Six sets of instruments will analyse the chemical composition of the atmosphere, observe the weather and topography of Titan, and examine the nature of its surface. Titan is larger than the planet Mercury, and its unique atmosphere rich in nitrogen and hydrocarbons may resemble the atmosphere of the primitive Earth, before life began. Nominal dates for the Huygens mission are as follows: - launch, 6 October 1997 - arrival at Saturn, 26 June 2004 - release of Huygens, 6 November 2004 - entry into Titan's atmosphere, 27 November 2004. The Saturn Orbiter, the other element in the Cassini mission, will relay the signals from Huygens to the Earth, before settling down to prolonged observations of Saturn and its rings and moons. European and American scientists are partners in all the experiments, both in the Orbiter and in the Huygens Probe. Farthest out for Europe Huygens will travel to a greater distance from the Sun than any previous ESA mission, out

  15. Saturn from Cassini-Huygens

    CERN Document Server

    Dougherty, Michele K; Krimigis, Stamatios M

    2009-01-01

    This book reviews our current knowledge of Saturn featuring the latest results obtained by the Cassini-Huygens mission. A global author team addresses the planet’s origin and evolution, internal structure, composition and chemistry, the atmosphere and ionosphere, the magnetosphere, as well as its ring system. Furthermore, Saturn's icy satellites are discussed. The book closes with an outlook beyond the Cassini-Huygens mission. Colorfully illustrated, this book will serve as a reference to researchers as well as an introduction for students.

  16. Dust characteristics of dusty plasma ring of Saturn

    Science.gov (United States)

    Morooka, M.; Wahlund, J.-E.; Ye, S.-Y.; Persoon, A. M.; Kurth, W. S.

    2017-09-01

    During the Ring Grazing orbit, starting from December 2016, Cassini carried out twenty of the faint Saturn ring crossing observations at the distance of 2.45-2.51 RS (1RS 60,268 km) from Saturn center. We will show the electron and the ion density measurements of the RPWS/Langmuir Probe (LP) during these orbits. In most of the orbits significant ion/electron density differences have been observed, which indicates the presence of the charged nm and µm sized grains. The relationship between the observed charge densities and the electrical potential of the grains shows that the grains and the ambient electrons and ions are electro dynamical ensemble, a dusty plasma. The results show that characteristic dust size changes depending on the distance from the ring center. The result suggests that a dusty plasma state is related to the dynamics of the grain sizes.

  17. A giant thunderstorm on Saturn.

    Science.gov (United States)

    Fischer, G; Kurth, W S; Gurnett, D A; Zarka, P; Dyudina, U A; Ingersoll, A P; Ewald, S P; Porco, C C; Wesley, A; Go, C; Delcroix, M

    2011-07-06

    Lightning discharges in Saturn's atmosphere emit radio waves with intensities about 10,000 times stronger than those of their terrestrial counterparts. These radio waves are the characteristic features of lightning from thunderstorms on Saturn, which last for days to months. Convective storms about 2,000 kilometres in size have been observed in recent years at planetocentric latitude 35° south (corresponding to a planetographic latitude of 41° south). Here we report observations of a giant thunderstorm at planetocentric latitude 35° north that reached a latitudinal extension of 10,000 kilometres-comparable in size to a 'Great White Spot'-about three weeks after it started in early December 2010. The visible plume consists of high-altitude clouds that overshoot the outermost ammonia cloud layer owing to strong vertical convection, as is typical for thunderstorms. The flash rates of this storm are about an order of magnitude higher than previous ones, and peak rates larger than ten per second were recorded. This main storm developed an elongated eastward tail with additional but weaker storm cells that wrapped around the whole planet by February 2011. Unlike storms on Earth, the total power of this storm is comparable to Saturn's total emitted power. The appearance of such storms in the northern hemisphere could be related to the change of seasons, given that Saturn experienced vernal equinox in August 2009. ©2011 Macmillan Publishers Limited. All rights reserved

  18. Spallation neutron experiment at SATURNE

    Energy Technology Data Exchange (ETDEWEB)

    Meigo, Shin-ichiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-11-01

    The double differential cross sections for (p,xn) reactions and the spectra of neutrons produced from the thick target have been measured at SATURNE in SACLAY from 1994 to 1997. The status of the experiment and the preliminary experimental results are presented. (author)

  19. Charged Grains In Saturn's F-Ring: Interaction With Saturn's Magnetic Field

    OpenAIRE

    Matthews, L. S.; Hyde, T. W.

    2003-01-01

    Saturn's dynamic F-Ring still presents a challenge for understanding and explaining the kinematic processes that lead to the changing structure visible in our observations of this ring. This study examines the effect of Saturn's magnetic field on the dynamics of micron-sized grains that may become electrically charged due to interaction with plasma in Saturn's rigidly corotating magnetosphere. The numerical model calculates the dynamics of charged dust grains and includes forces due to Saturn...

  20. Edge-on View of Saturn's Rings

    Science.gov (United States)

    1996-01-01

    TOP - This is a NASA Hubble Space Telescope snapshot of Saturn with its rings barely visible. Normally, astronomers see Saturn with its rings tilted. Earth was almost in the plane of Saturn's rings, thus the rings appear edge-on.In this view, Saturn's largest moon, Titan, is casting a shadow on Saturn. Titan's atmosphere is a dark brown haze. The other moons appear white because of their bright, icy surfaces. Four moons - from left to right, Mimas, Tethys, Janus, and Enceladus - are clustered around the edge of Saturn's rings on the right. Two other moons appear in front of the ring plane. Prometheus is on the right edge; Pandora, on the left. The rings also are casting a shadow on Saturn because the Sun was above the ring plane.BOTTOM - This photograph shows Saturn with its rings slightly tilted. The moon called Dione, on the lower right, is casting a long, thin shadow across the whole ring system due to the setting Sun on the ring plane. The moon on the upper left of Saturn is Tethys.Astronomers also are studying the unusual appearance of Saturn's rings. The bottom image displays a faint, narrow ring, the F-ring just outside the main ring, which normally is invisible from Earth. Close to the edge of Saturn's disk, the front section of rings seem brighter and more yellow than the back due to the additional lumination by yellowish Saturn.The color images were assembled from separate exposures taken August 6 (top) and November 17 (bottom), 1995 with the Wide Field Planetary Camera-2.The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  1. Future studies of planetary rings by space probes

    Science.gov (United States)

    Stone, E. C.

    1984-01-01

    Recent space probe observations of the rings of Jupiter and Saturn have furnished a substantial enhancement of the current understanding of the outer planets' rings. Voyager 2 offers further opportunities for the study of the Neptune and Uranus ring systems. The Galileo mission to Jupiter furnishes the first opportunity for long term space probe studies of a planetary ring system. It is suggested that an appropriately instrumented Saturn orbiter would not only provide a similar opportunity for the study of the Saturn rings, but may also be the only means by which to adequately address the nature of the diverse phenomena displayed by this prototypical planetary ring system.

  2. The Irregular Moons of Saturn

    Science.gov (United States)

    Denk, Tilmann; Mottola, Stefano; Tosi, Federico; Bottke, William; Hamilton, Douglas P.

    2017-10-01

    The 38 irregular moons of Saturn, all but Phoebe discovered between 2000 and 2007, outnumber the planet's classical satellites. Observations from the ground and from near-Earth space have revealed orbits, sizes, and colors and have hinted at the existence of dynamical families, indicative of collisional evolution and common progenitors. More recently, remote observations of many irregular satellites with the Cassini spacecraft produced lightcurves that helped determine rotational periods, coarse shape models, potential hemispheric color heterogeneities, and other basic properties.From Cassini, a total of 25 Saturnian irregulars have been observed with the ISS camera. Their rotational periods range from 5.45 h to 76.13 h. The absence of fast rotators is evident. Among main-belt asteroids of the same size range (~4 to ~45 km), one third of the objects have faster rotations, indicating that many irregulars should be low-density objects.While the origin of the irregulars is still debated, capture of comets via three-body interactions during giant planets encounters does the best job thus far at reproducing the observed prograde/retrograde orbits. Data from the ground, near-Earth spacecraft, and Cassini as well as modeling results suggest the population visible today has experienced substantial collisional evolution. It may be that only Phoebe has survived relatively intact. The small particle debris drifts toward Saturn by P-R drag, with most of it swept up by Titan. Only remnants of this process are visible today.Our current knowledge on the Saturnian irregulars will be summarized in a chapter [1] in the book "Enceladus and the Icy Moons of Saturn" [2]. The talk will give an overview on the chapter's content, which covers the following topics: Orbital "architecture" (a,e,i), sizes and colors, Cassini observations and results, Phoebe, origin, an outlook.[1] Denk, T., Mottola, S., Tosi, F., Bottke, W.F., Hamilton, D.P. (2018): The Irregular Satellites of Saturn. In

  3. About separation and collision of Saturn rings particles

    Science.gov (United States)

    Tchernyi (Cherny), Vladimir

    There is no yet clear picture of the origin of Saturn's rings. We follow importance of electromag-netic idea that rings could originate and form from the frozen particles of the protoplanetary cloud after the appearance of the magnetic field of Saturn due to electromagnetic interaction of icy particles with the planetary magnetic field. The Sun heats the rings weakly, temperature in the area of the rings is about 70-110 K. It makes possible the existence of the superconduct-ing substance in the space behind the belt of asteroids. Theoretical electromagnetic modeling demonstrates that superconductivity can be the physical reason of the origin of the sombrero of rings of Saturn from the frozen particles of the protoplanetary cloud. The sombrero appears during some time after magnetic field of planet appears. Finally, all the Kepler's orbits of the superconducting particles are localizing as a sombrero disk of rings in the magnetic equator plane, where the energy of particles in the magnetic field of Saturn has a minimum value. Recently space probe "Cassini" discovered collisions and separation of the Saturn's rings parti-cles. It is also important fact that from electromagnetic modeling follows possibility of collide of the rings particles on the vertical direction within the width of the sombrero. It could be a reason for the formation of the particles of the bigger size due to coalescence, until gravity and centrifugal force will destroy them to the particles of smaller size again. From the solution of the electromagnetic problem we will demonstrate how rings of Saturn could be originated from the iced particles located within the protoplanetary cloud. Before appearance of the magnetic field of Saturn all particles within the protoplanetary cloud are located on such an orbit as Kepler's, where there is a balance of the force of gravity and the centrifugal force. With the occurrence of the magnetic field of the Saturn the superconducting particles of the protoplane

  4. About separation and collision of the Saturn rings particles

    Science.gov (United States)

    Tchernyi (Cherny), Vladimir

    There is no yet clear picture of the origin of Saturn's rings. We follow importance of electromag-netic idea that rings could originate and form from the frozen particles of the protoplanetary cloud after the appearance of the magnetic field of Saturn due to electromagnetic interaction of icy particles with the planetary magnetic field. The Sun heats the rings weakly, temperature in the area of the rings is about 70-110 K. It makes possible the existence of the superconduct-ing substance in the space behind the belt of asteroids. Theoretical electromagnetic modeling demonstrates that superconductivity can be the physical reason of the origin of the sombrero of rings of Saturn from the frozen particles of the protoplanetary cloud. The sombrero appears during some time after magnetic field of planet appears. Finally, all the Kepler's orbits of the superconducting particles are localizing as a sombrero disk of rings in the magnetic equator plane, where the energy of particles in the magnetic field of Saturn has a minimum value. Recently space probe "Cassini" discovered collisions and separation of the Saturn's rings parti-cles. It is also important fact that from electromagnetic modeling follows possibility of collide of the rings particles on the vertical direction within the width of the sombrero. It could be a reason for the formation of the particles of the bigger size due to coalescence, until gravity and centrifugal force will destroy them to the particles of smaller size again. From the solution of the electromagnetic problem we will demonstrate how rings of Saturn could be originated from the iced particles located within the protoplanetary cloud. Before appearance of the magnetic field of Saturn all particles within the protoplanetary cloud are located on such an orbit as Kepler's, where there is a balance of the force of gravity and the centrifugal force. With the occurrence of the magnetic field of the Saturn the superconducting particles of the protoplane

  5. Edges of Saturn's rings are fractal.

    Science.gov (United States)

    Li, Jun; Ostoja-Starzewski, Martin

    2015-01-01

    The images recently sent by the Cassini spacecraft mission (on the NASA website http://saturn.jpl.nasa.gov/photos/halloffame/) show the complex and beautiful rings of Saturn. Over the past few decades, various conjectures were advanced that Saturn's rings are Cantor-like sets, although no convincing fractal analysis of actual images has ever appeared. Here we focus on four images sent by the Cassini spacecraft mission (slide #42 "Mapping Clumps in Saturn's Rings", slide #54 "Scattered Sunshine", slide #66 taken two weeks before the planet's Augus't 200'9 equinox, and slide #68 showing edge waves raised by Daphnis on the Keeler Gap) and one image from the Voyager 2' mission in 1981. Using three box-counting methods, we determine the fractal dimension of edges of rings seen here to be consistently about 1.63 ~ 1.78. This clarifies in what sense Saturn's rings are fractal.

  6. Fluorescent hydroxyl emissions from Saturn's ring atmosphere.

    Science.gov (United States)

    Hall, D T; Feldman, P D; Holberg, J B; McGrath, M A

    1996-04-26

    Just before earth passed through Saturn's ring plane on 10 August 1995, the Hubble Space Telescope Faint Object Spectrograph detected ultraviolet fluorescent emissions from a tenuous atmosphere of OH molecules enveloping the rings. Brightnesses decrease with increasing distance above the rings, implying a scale height of about 0.45 Saturn radii (Rs). A spatial scan 0.28Rs above the A and B rings indicates OH column densities of about 10(13) cm(-2) and number densities of up to 700 cm(-3). Saturn's rings must produce roughly 10(25) to 10(29) OH molecules per second to maintain the observed OH distribution.

  7. Cassini CIRS Observations of Saturn's Rings

    Science.gov (United States)

    Spilker, Linda J.; Pilorz, Stuart H.; Wallis, Brad D.; Brooks, Shawn M.; Edgington, Scott G.; Flasar, F. Michael; Pearl, John C.; Showalter, Mark R.; Ferrari, Cecile; Achterberg, Richard K.

    2005-01-01

    In the spring of 2004, during Cassini s approach to Saturn, the Cassini Composite Infrared Spectrometer (CIRS) began acquiring thermal spectra of Saturn s rings. CIRS is a Fourier-transform spectrometer that measures radiation in the thermal infrared from 7 microns to 1 millimeter (1400 to 10/cm). CIRS has a set of 21 detectors, consisting of two 1 x 10 linear arrays with a pixel size of 0.3 mrad, and one 4 mrad circular detector. Just after the completion of the Saturn orbit insertion (SOI) burn, CIRS performed an especially high spatial resolution scan of portions of Saturn s A, B and C rings. In the months following SOI, additional ring measurements have been obtained, including radial scans on the lit and unlit sides of the rings, and azimuthal scans across the shadowed regions of the A, B and C rings.

  8. SATURN. Studying Atmospheric Pollution in Urban Areas

    DEFF Research Database (Denmark)

    Moussiopoulos, N.; Hout, K. D. van den; Mestayer, P.

    SATURN is a subproject under EUROTRAC-2. (EUROTRAC-2 is the EUREKA Project on the Transport and Chemical Transformation of Environmentally Relevant Trace Constituents in the Troposphere over Europe; Second Phase)....

  9. The Cassini-Huygens Mission to Saturn and Titan

    Science.gov (United States)

    Lunine, Jonathan I.; Pappalardo, R. T.; Matson, D. L.

    2008-09-01

    The Cassini-Huygens exploration of Saturn has completed its prime mission and is now entering a two-year phase called the Equinox Mission. During its four-year tour of Saturn, the Cassini Orbiter found intricate dynamical structures hidden below the haze of Saturn's atmosphere, a previously unseen inner radiation belt, unexpected "channel" structures in the B-ring where opacity changes dramatically over just a few kilometers, an active Enceladus with plumes that are the source of the E-ring and the engine supplying particles to the Saturnian magnetosphere, and a methane hydrologic cycle on Titan that is a remarkable analog of the Earth's. The epic descent of the Huygens probe to a landing on Titan's surface in 2005 provided vistas of dendritic channels presumably carved by methane in ice hills, and key data on nitrogen and noble gases that bespeak an active past in which ammonia was converted to the molecular nitrogen we see today. Cassini's two year Equinox mission will allow for key scientific objectives to be pursued that follow from discoveries made during the prime mission. For example, the source of the Enceladus plumes may be either liquid water or warm ice, given what is known at present. Liquid water has important implications for the potential for life under Enceladus' surface, since both water and organic molecules are present in the plumes. Seven flybys will provide an opportunity to address this problem. For Titan, being able to observe the northern hemisphere lakes in sunlight affords the possibility of detecting ethane in the lakes, as has recently been done in the south, and of observing changes as the seasons proceed. An opportunity to see the rings at low solar incidence angle will allow the three-dimensional structure to be inferred. Seasonal and solar cycle changes in the Saturnian aurora are expected and will be tracked.

  10. US Ports of Entry

    Data.gov (United States)

    Department of Homeland Security — HSIP Non-Crossing Ports-of-Entry A Port of Entry is any designated place at which a CBP officer is authorized to accept entries of merchandise to collect duties, and...

  11. Origin and Evolution of Saturn's Ring System

    OpenAIRE

    Charnoz, Sebastien; Dones, Luke; Esposito, Larry W.; Estrada, Paul R.; Hedman, Matthew M.

    2009-01-01

    The origin and long-term evolution of Saturn's rings is still an unsolved problem in modern planetary science. In this chapter we review the current state of our knowledge on this long-standing question for the main rings (A, Cassini Division, B, C), the F Ring, and the diffuse rings (E and G). During the Voyager era, models of evolutionary processes affecting the rings on long time scales (erosion, viscous spreading, accretion, ballistic transport, etc.) had suggested that Saturn's rings are...

  12. Long term observations of Saturn's northern auroras

    Science.gov (United States)

    Nichols, Jonathan

    2011-10-01

    Auroral emissions are a vital tool in diagnosing the dynamics of planetary magnetospheres. While SaturnA?s southern UV auroras have been observed with high-sensitivity cameras onboard the Hubble Space Telescope {HST}, the northern auroras have only been observed at very oblique angles. Our understanding of SaturnA?s auroral emissions is thus only half complete. However, Saturn has now passed equinox and is moving toward summer in the northern hemisphere, such that the northern auroras are now visible from Earth, and recent results from HST have indicated that SaturnA?s northern auroras are not simply mirror images of the southern. The changing seasons are also expected to result in significant changes in magnetospheric phenomena related to the auroras. Observing these changes is a specific goal of the Cassini Solstice Mission {CSM} and, since joint HST-Cassini observations have repeatedly proved to be invaluable, CSM operations are currently being planned specifically with joint HST observations in mind. The observations proposed here will thus execute over Cycles 18-20, and will address the following science questions:What is the morphology of SaturnA?s northern auroras? Do SaturnA?s auroras change with the planetA?s season? How are the auroral emissions of different wavelengths related?The importance of long term HST observations of SaturnA?s northern auroras are highlighted by the fact that recent key discoveries would have been missed without the multiyear archive of observations of the planetA?s southern auroras. The opportunity to obtain HST images while Cassini makes specifically-tailored supporting observations is an extremely valuable opportunity, and HST is the only instrument capable of providing sustained, high time resolution observations of Saturns auroral emission.

  13. Polar heating in Saturn's thermosphere

    Directory of Open Access Journals (Sweden)

    C. G. A. Smith

    2005-10-01

    Full Text Available A 3-D numerical global circulation model of the Kronian thermosphere has been used to investigate the influence of polar heating. The distributions of temperature and winds resulting from a general heat source in the polar regions are described. We show that both the total energy input and its vertical distribution are important to the resulting thermal structure. We find that the form of the topside heating profile is particularly important in determining exospheric temperatures. We compare our results to exospheric temperatures from Voyager occultation measurements (Smith et al., 1983; Festou and Atreya, 1982 and auroral H3+ temperatures from ground-based spectroscopic observations (e.g. Miller et al., 2000. We find that a polar heat source is consistent with both the Smith et al. determination of T∞~400 K at ~30° N and auroral temperatures. The required heat source is also consistent with recent estimates of the Joule heating rate at Saturn (Cowley et al., 2004. However, our results show that a polar heat source can probably not explain the Festou and Atreya determination of T∞~800 K at ~4° N and the auroral temperatures simultaneously. Keywords. Ionosphere (Planetary ionosphere – Magnetospherica physics (Planetary magnetospheres – Meterology and atmospheric dynamics (Thermospheric dynamics

  14. D/H Ratios on Saturn and Jupiter from Cassini CIRS

    Science.gov (United States)

    Pierel, J. D. R.; Nixon, C. A.; Lellouch, E.; Fletcher, L. N.; Bjoraker, G. L.; Achterberg, R. K.; Bézard, B.; Hesman, B. E.; Irwin, P. G. J.; Flasar, F. M.

    2017-11-01

    We present new measurements of the deuterium abundance on Jupiter and Saturn, showing evidence that Saturn’s atmosphere contains less deuterium than Jupiter’s. We analyzed far-infrared spectra from the Cassini Composite Infrared Spectrometer to measure the abundance of HD on both giant planets. Our estimate of the Jovian D/H = (2.95 ± 0.55) × 10-5 is in agreement with previous measurements by ISO/SWS: (2.25 ± 0.35) × 10-5, and the Galileo probe: (2.6 ± 0.7) × 10-5. In contrast, our estimate of the Saturn value of (2.10 ± 0.13) × 10-5 is somewhat lower than on Jupiter (by a factor of {0.71}-0.15+0.22), contrary to model predictions of a higher ratio: Saturn/Jupiter = 1.05-1.20. The Saturn D/H value is consistent with estimates for hydrogen in the protosolar nebula (2.1 ± 0.5) × 10-5, but its apparent divergence from the Jovian value suggests that our understanding of planetary formation and evolution is incomplete, which is in agreement with previous work.

  15. Equatorial Oscillations in Jupiter's and Saturn's Atmospheres

    Science.gov (United States)

    Flasar, F. Michael; Guerlet, S.; Fouchet, T.; Schinder, P. J.

    2011-01-01

    Equatorial oscillations in the zonal-mean temperatures and zonal winds have been well documented in Earth's middle atmosphere. A growing body of evidence from ground-based and Cassini spacecraft observations indicates that such phenomena also occur in the stratospheres of Jupiter and Saturn. Earth-based midinfrared measurements spanning several decades have established that the equatorial stratospheric temperatures on Jupiter vary with a cycle of 4-5 years and on Saturn with a cycle of approximately 15 years. Spectra obtained by the Composite Infrared Spectrometer (CIRS) during the Cassini swingby at the end of 2000, with much better vertical resolution than the ground-based data, indicated a series of vertically stacked warm and cold anomalics at Jupiter's equator; a similar structurc was seen at Saturn's equator in CIRS limb measurements made in 2005, in the early phase of Cassini's orbital tour. The thermal wind equation implied similar patterns of mean zonal winds increasing and decreasing with altitude. On Saturn the peak-to-pcak amplitude of this variation was nearly 200 meters per second. The alternating vertical pattern of wanner and colder cquatorial tcmperatures and easterly and westerly tendencies of the zonal winds is seen in Earth's equatorial oscillations, where the pattern descends with time, The Cassini Jupiter and early Saturn observations were snapshots within a limited time interval, and they did not show the temporal evolution of the spatial patterns. However, more recent Saturn observations by CIRS (2010) and Cassini radio-occultation soundings (2009-2010) have provided an opportunity to follow the change of the temperature-zonal wind pattern, and they suggest there is descent, at a rate of roughly one scale height over four years. On Earth, the observed descent in the zonal-mean structure is associated with the absorption of a combination of vertically propagating waves with easlerly and westerly phase velocities. The peak-to-peak zonal wind

  16. Managing Cassini Safe Mode Attitude at Saturn

    Science.gov (United States)

    Burk, Thomas A.

    2010-01-01

    The Cassini spacecraft was launched on October 15, 1997 and arrived at Saturn on June 30, 2004. It has performed detailed observations and remote sensing of Saturn, its rings, and its satellites since that time. In the event safe mode interrupts normal orbital operations, Cassini has flight software fault protection algorithms to detect, isolate, and recover to a thermally safe and commandable attitude and then wait for further instructions from the ground. But the Saturn environment is complex, and safety hazards change depending on where Cassini is in its orbital trajectory around Saturn. Selecting an appropriate safe mode attitude that insures safe operation in the Saturn environment, including keeping the star tracker field of view clear of bright bodies, while maintaining a quiescent, commandable attitude, is a significant challenge. This paper discusses the Cassini safe table management strategy and the key criteria that must be considered, especially during low altitude flybys of Titan, in deciding what spacecraft attitude should be used in the event of safe mode.

  17. Trapped radiation belts of Saturn - First look

    Science.gov (United States)

    Fillius, W.; Ip, W. H.; Mcilwain, C. E.

    1980-01-01

    Data on the magnetosphere of Saturn obtained with the trapped radiation detector package on board the Pioneer 11 spacecraft is reported. Radiation belt profiles determined by the trapped radiation detectors on Pioneer 10 and 11 indicate that Saturn's magnetosphere is intermediate in size between those of the earth and Jupiter, with particle intensities similar to those of the earth. The outer region of the Saturn magnetosphere is found to contain particles of lower energy than the outer region, being strongly influenced by the time-varying solar wind. The moons and rings of Saturn are observed to be effective absorbers of trapped particles, confirming the discoveries of the F ring, the Pioneer ring division and the moon 1979 S 2. Particle diffusion rates are used to estimate a cross-sectional area of greater than 7 x 10 to the 13th sq cm and an opacity greater than 0.00001 for the F ring. It is suggested that cosmic-ray albedo neutron decay be studied as a possible source of energetic particles in the inner magnetosphere of Saturn.

  18. Polarization of Saturn's moon Iapetus

    Science.gov (United States)

    Ejeta, C. T.; Boehnhardt, H.; Bagnulo, S.; Muinonen, K.; Kolokolova, L.; Tozzi, G.

    2012-12-01

    One way to constrain the surface properties of atmosphereless solar system objects is to investigate the properties of the polarized light scattered from their surfaces. Using FORS2 instrument of the ESO VLT, we have carried out a series of polarization measurements of Saturn's moon Iapetus, with an accuracy of ~0.1%, over the maximum phase angle range accessible from the ground (~ 6.0 deg), and over a broad spectral range (400 - 900 nm); thereby identifying the polarimetric characteristics of the bright surface material on its trailing side and, that of the dark material on its leading side. While our linear polarizatiom measurements of Iapetus' two hemispheres show an opposite trend of phase angle dependence, the polarization values measured for the two hemispheres around similar phase angles (between ~3 - 6.0deg) differ by a factor of three. Aimed at providing a quantitative assessment of the polarization observed for Iapetus, we have also carried out simulation of the scattering and absorption properties of light by a medium consisting of spherical volume of randomly positioned monodisperse particles. For this purpose, we used the numerically exact solutions of the Maxwell equations employing the multiple sphere T-matrix method [1]. The modeling entails physical characteristics of the particulate surface such as, porosity of the particulate medium; the number of constituent particles; the size, and optical properties of the scatterers. Our model has retrived, a particle size of ~ 0.10 ≤ r ≤ 0.20μm is dominating both the dark and bright material of Iapetus. Moreover, utilizing the scattering matrix parametrization for single-particle scattering with double Henyey-Greenstein (2HG) scattering phase function, to characterize the resulting multiple scattering, we have carried out coherent backscattering simulations for a spherical random media of scatterers [2], with the goal to obtain polarimetric phase function of Iapetus. The geometric albedo values of

  19. Spin of Planetary Probes in Atmospheric Flight

    Science.gov (United States)

    Lorenz, R. D.

    Probes that enter planetary atmospheres are often spun during entry or descent for a variety of reasons. Their spin rate histories are influenced by often subtle effects. The spin requirements, control methods and flight experience from planetary and earth entry missions are reviewed. An interaction of the probe aerodynamic wake with a drogue parachute, observed in Gemini wind tunnel tests, is discussed in connection with the anomalous spin behaviour of the Huygens probe.

  20. Hydrocarbons on the Icy Satellites of Saturn

    Science.gov (United States)

    Cruikshank, Dale P.

    2010-01-01

    The Visible-Infrared Mapping Spectrometer on the Cassini Spacecraft has obtained spectral reflectance maps of the satellites of Saturn in the wavelength region 0.4-5.1 micrometers since its insertion into Saturn orbit in late 2004. We have detected the spectral signature of the C-H stretching molecular mode of aromatic and aliphatic hydrocarbons in the low albedo material covering parts of several of Saturn's satellites, notably Iapetus and Phoebe (Cruikshank et al. 2008). The distribution of this material is complex, and in the case of Iapetus we are seeking to determine if it is related to the native grey-colored materials left as lag deposits upon evaporation of the ices, or represents in-fall from an external source, notably the newly discovered large dust ring originating at Phoebe. This report covers our latest exploration of the nature and source of this organic material.

  1. Nanograin densities outside Saturn's A-ring

    CERN Document Server

    Johnson, Robert E; Elrod, Meredith K; Persoon, Ann M

    2016-01-01

    The observed disparity between the radial dependence of the ion and electron densities measured by the Cassini plasma and radio science instruments are used to show that the region between the outer edge of Saturn's main rings and its tenuous G-ring is permeated with small charged grains (nanograins). These grains emanate from the edge of the A-ring and from the tenuous F-ring and G-ring. This is a region of Saturn's magnetosphere that is relatively unexplored, but will be a focus of Cassini's F-ring orbits prior to the end of mission in September 2017. Confirmation of the grain densities predicted here will enhance our ability to describe the formation and destruction of material in this important region of Saturn's magnetosphere.

  2. An evolving view of Saturn's dynamic rings.

    Science.gov (United States)

    Cuzzi, J N; Burns, J A; Charnoz, S; Clark, R N; Colwell, J E; Dones, L; Esposito, L W; Filacchione, G; French, R G; Hedman, M M; Kempf, S; Marouf, E A; Murray, C D; Nicholson, P D; Porco, C C; Schmidt, J; Showalter, M R; Spilker, L J; Spitale, J N; Srama, R; Sremcević, M; Tiscareno, M S; Weiss, J

    2010-03-19

    We review our understanding of Saturn's rings after nearly 6 years of observations by the Cassini spacecraft. Saturn's rings are composed mostly of water ice but also contain an undetermined reddish contaminant. The rings exhibit a range of structure across many spatial scales; some of this involves the interplay of the fluid nature and the self-gravity of innumerable orbiting centimeter- to meter-sized particles, and the effects of several peripheral and embedded moonlets, but much remains unexplained. A few aspects of ring structure change on time scales as short as days. It remains unclear whether the vigorous evolutionary processes to which the rings are subject imply a much younger age than that of the solar system. Processes on view at Saturn have parallels in circumstellar disks.

  3. Saturn facility oil transfer automation system

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Nathan R.; Thomas, Rayburn Dean; Lewis, Barbara Ann; Malagon, Hector Ricardo.

    2014-02-01

    The Saturn accelerator, owned by Sandia National Laboratories, has been in operation since the early 1980s and still has many of the original systems. A critical legacy system is the oil transfer system which transfers 250,000 gallons of transformer oil from outside storage tanks to the Saturn facility. The oil transfer system was iden- ti ed for upgrade to current technology standards. Using the existing valves, pumps, and relay controls, the system was automated using the National Instruments cRIO FGPA platform. Engineered safety practices, including a failure mode e ects analysis, were used to develop error handling requirements. The uniqueness of the Saturn Oil Automated Transfer System (SOATS) is in the graphical user interface. The SOATS uses an HTML interface to communicate to the cRIO, creating a platform independent control system. The SOATS was commissioned in April 2013.

  4. On the evolution of Saturn's 'Spokes' - Theory

    Science.gov (United States)

    Morfill, G. E.; Gruen, E.; Goertz, C. K.; Johnson, T. V.

    1983-01-01

    Starting with the assumption that negatively charged micron-sized dust grains may be elevated above Saturn's ring plane by plasma interactions, the subsequent evolution of the system is discussed. The discharge of the fine dust by solar UV radiation produces a cloud of electrons which moves adiabatically in Saturn's dipolar magnetic field. The electron cloud is absorbed by the ring after one bounce, alters the local ring potential significantly, and reduces the local Debye length. As a result, more micron-sized dust particles may be elevated above the ring plane and the spoke grows. This process continues until the electron cloud has dissipated.

  5. Conformal Ablative Thermal Protection Systems (CA-TPS) for Venus and Saturn Backshells

    Science.gov (United States)

    Beck, R.; Gasch, M.; Stackpoole, M.; Wilder, M.; Boghozian, T.; Chavez-Garcia, J.; Prabhu, Dinesh; Kazemba, Cole D.; Venkatapathy, E.

    2016-01-01

    This poster provides an overview of the work performed to date on the Conformal Ablative TPS (CA-TPS) element of the TPSM project out of GCDP. Under this element, NASA is developing improved ablative TPS materials based on flexible felt for reinforcement rather than rigid reinforcements. By replacing the reinforcements with felt, the resulting materials have much higher strain-to-failure and are much lower in thermal conductivity than their rigid counterparts. These characteristics should allow for larger tile sizes, direct bonding to aeroshells and even lower weight TPS. The conformal phenolic impregnated carbon felt (C-PICA) is a candidate for backshell TPS for both Venus and Saturn entry vehicles.

  6. Drifting waves in Saturn's C ring, evidence for changes in Saturn's interior

    Science.gov (United States)

    Hedman, Matthew M.; El Moutamid, Maryame; Nicholson, Philip D.

    2017-06-01

    Recent analyses of spiral density waves in Saturn's C ring have revealed that many of these waves are generated by either normal-mode oscillations or asymmetries in Saturn's interior. The waves generated by normal-mode oscillations exhibit remarkably stable pattern speeds, indicating that the oscillations inside the planet that generate these waves have frequencies that remain constant for years to decades. However, close inspection of the waves with pattern speeds close to Saturn's rotation rate reveals that several of these waves have been moving inwards over the course of the Cassini mission at rates of around 1 kilometer per year. These "drifting waves" suggest that the frequencies of the relevant driving forces are increasing over time. Hence some aspect of Saturn's internal structure must be slowly changing on decadal timescales. Furthermore, since these waves are generated by forces that are not strictly periodic, they provide new opportunities to examine how disturbances propagate within dense rings.

  7. Saturn's Rings, the Yarkovsky Effects, and the Ring of Fire

    Science.gov (United States)

    Rubincam, David Parry

    2004-01-01

    The dimensions of Saturn's A and B rings may be determined by the seasonal Yarkovsky effect and the Yarkovsky-Schach effect; the two effects confine the rings between approximately 1.68 and approximately 2.23 Saturn radii, in reasonable agreement with the observed values of 1.525 and 2.267. The C ring may be sparsely populated because its particles are transients on their way to Saturn; the infall may create a luminous Ring of Fire around Saturn's equator. The ring system may be young: in the past heat flow from Saturn's interior much above its present value would not permit rings to exist.

  8. An isolated, bright cusp aurora at Saturn

    Science.gov (United States)

    Kinrade, J.; Badman, S. V.; Bunce, E. J.; Tao, C.; Provan, G.; Cowley, S. W. H.; Grocott, A.; Gray, R. L.; Grodent, D.; Kimura, T.; Nichols, J. D.; Arridge, C. S.; Radioti, A.; Clarke, J. T.; Crary, F. J.; Pryor, W. R.; Melin, H.; Baines, K. H.; Dougherty, M. K.

    2017-06-01

    Saturn's dayside aurora displays a number of morphological features poleward of the main emission region. We present an unusual morphology captured by the Hubble Space Telescope on 14 June 2014 (day 165), where for 2 h, Saturn's FUV aurora faded almost entirely, with the exception of a distinct emission spot at high latitude. The spot remained fixed in local time between 10 and 15 LT and moved poleward to a minimum colatitude of 4°. It was bright and persistent, displaying intensities of up to 49 kR over a lifetime of 2 h. Interestingly, the spot constituted the entirety of the northern auroral emission, with no emissions present at any other local time—including Saturn's characteristic dawn arc, the complete absence of which is rarely observed. Solar wind parameters from propagation models, together with a Cassini magnetopause crossing and solar wind encounter, indicate that Saturn's magnetosphere was likely to have been embedded in a rarefaction region, resulting in an expanded magnetosphere configuration during the interval. We infer that the spot was sustained by reconnection either poleward of the cusp or at low latitudes under a strong component of interplanetary magnetic field transverse to the solar wind flow. The subsequent poleward motion could then arise from either reconfiguration of successive open field lines across the polar cap or convection of newly opened field lines. We also consider the possible modulation of the feature by planetary period rotating current systems.

  9. Saturn Ring Data Analysis and Thermal Modeling

    Science.gov (United States)

    Dobson, Coleman

    2011-01-01

    CIRS, VIMS, UVIS, and ISS (Cassini's Composite Infrared Specrtometer, Visual and Infrared Mapping Spectrometer, Ultra Violet Imaging Spectrometer and Imaging Science Subsystem, respectively), have each operated in a multidimensional observation space and have acquired scans of the lit and unlit rings at multiple phase angles. To better understand physical and dynamical ring particle parametric dependence, we co-registered profiles from these three instruments, taken at a wide range of wavelengths, from ultraviolet through the thermal infrared, to associate changes in ring particle temperature with changes in observed brightness, specifically with albedos inferred by ISS, UVIS and VIMS. We work in a parameter space where the solar elevation range is constrained to 12 deg - 14 deg and the chosen radial region is the B3 region of the B ring; this region is the most optically thick region in Saturn's rings. From this compilation of multiple wavelength data, we construct and fit phase curves and color ratios using independent dynamical thermal models for ring structure and overplot Saturn, Saturn ring, and Solar spectra. Analysis of phase curve construction and color ratios reveals thermal emission to fall within the extrema of the ISS bandwidth and a geometrical dependence of reddening on phase angle, respectively. Analysis of spectra reveals Cassini CIRS Saturn spectra dominate Cassini CIRS B3 Ring Spectra from 19 to 1000 microns, while Earth-based B Ring Spectrum dominates Earth-based Saturn Spectrum from 0.4 to 4 microns. From our fits we test out dynamical thermal models; from the phase curves we derive ring albedos and non-lambertian properties of the ring particle surfaces; and from the color ratios we examine multiple scattering within the regolith of ring particles.

  10. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff Mathiasen, Anne-Gitte

    2013-01-01

    Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  11. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff, Anne-Gitte

    2012-01-01

    and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings......Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  12. Saturn ring particles as dynamic ephemeral bodies.

    Science.gov (United States)

    Davis, D R; Weidenschilling, S J; Chapman, C R; Greenberg, R

    1984-05-18

    Although Saturn's rings are within the Roche zone, the accretion of centimeter-sized particles into large aggregates many meters in diameter occurs readily, on a time scale of weeks. These aggregates are disrupted when tidal stresses exceed their very low strengths; thus most of the mass of the ring system is continually processed through a population of large "dynamic ephemeral bodies," which are continually forming and disintegrating. These large aggregates are not at all like the idealized ice spheres often used in modeling Saturn's ring dynamics. Their coefficient of restitution is low, hence they form a monolayer in the ring plane. The optically observable characteristics of the rings are dominated by the swarm of centimeter-sized particles.

  13. Intense Harmonic Emissions Observed in Saturn's Ionosphere

    Science.gov (United States)

    Sulaiman, A. H.; Kurth, W. S.; Persoon, A. M.; Menietti, J. D.; Farrell, W. M.; Ye, S.-Y.; Hospodarsky, G. B.; Gurnett, D. A.; Hadid, L. Z.

    2017-12-01

    The Cassini spacecraft's first Grand Finale orbit was carried out in April 2017. This set of 22 orbits had an inclination of 63° with a periapsis grazing Saturn's ionosphere, thus providing unprecedented coverage and proximity to the planet. Cassini's Radio and Plasma Wave Science instrument repeatedly detected intense electrostatic waves and their harmonics near closest approach in the dayside equatorial topside ionosphere. The fundamental modes were found to both scale and trend best with the H+ plasma or lower hybrid frequencies, depending on the plasma composition considered. The fine-structured harmonics are unlike previous observations, which scale with cyclotron frequencies. We explore their generation mechanism and show strong evidence of their association with whistler mode waves, consistent with theory. The possibility of Cassini's presence in the ionosphere influencing the resonance and harmonics is discussed. Given their link to the lower hybrid frequency, these emissions may offer clues to constraining Saturn's ionospheric properties.

  14. Size and shape of Saturn's moon Titan

    Science.gov (United States)

    Zebker, Howard A.; Stiles, Bryan; Hensley, Scott; Lorenz, Ralph; Kirk, Randolph L.; Lunine, Jonathan

    2009-01-01

    Cassini observations show that Saturn's moon Titan is slightly oblate. A fourth-order spherical harmonic expansion yields north polar, south polar, and mean equatorial radii of 2574.32 ± 0.05 kilometers (km), 2574.36 ± 0.03 km, and 2574.91 ± 0.11 km, respectively; its mean radius is 2574.73 ± 0.09 km. Titan's shape approximates a hydrostatic, synchronously rotating triaxial ellipsoid but is best fit by such a body orbiting closer to Saturn than Titan presently does. Titan's lack of high relief implies that most—but not all—of the surface features observed with the Cassini imaging subsystem and synthetic aperture radar are uncorrelated with topography and elevation. Titan's depressed polar radii suggest that a constant geopotential hydrocarbon table could explain the confinement of the hydrocarbon lakes to high latitudes.

  15. A dynamic, rotating ring current around Saturn.

    Science.gov (United States)

    Krimigis, S M; Sergis, N; Mitchell, D G; Hamilton, D C; Krupp, N

    2007-12-13

    The concept of an electrical current encircling the Earth at high altitudes was first proposed in 1917 to explain the depression of the horizontal component of the Earth's magnetic field during geomagnetic storms. In situ measurements of the extent and composition of this current were made some 50 years later and an image was obtained in 2001 (ref. 6). Ring currents of a different nature were observed at Jupiter and their presence inferred at Saturn. Here we report images of the ring current at Saturn, together with a day-night pressure asymmetry and tilt of the planet's plasma sheet, based on measurements using the magnetospheric imaging instrument (MIMI) on board Cassini. The ring current can be highly variable with strong longitudinal asymmetries that corotate nearly rigidly with the planet. This contrasts with the Earth's ring current, where there is no rotational modulation and initial asymmetries are organized by local time effects.

  16. Overview of Heatshield for Extreme Entry Environment Technology (HEEET)

    Science.gov (United States)

    Driver, David M.; Ellerby, Donald T.; Gasch, Matthew J.; Mahzari, Milad; Milos, Frank S.; Nishioka, Owen S.; Stackpoole, Margaret M.; Venkatapathy, Ethiraj; Young, Zion W.; Gage, Peter J.; hide

    2018-01-01

    The Heatshield for Extreme Entry Environment Technology (HEEET) projects objective is to mature a 3-D Woven Thermal Protection System (TPS) to Technical Readiness Level (TRL) 6 to support future NASA missions to destinations such as Venus and Saturn. The scope of the project, status of which will be discussed, encompasses development of manufacturing and integration processes, fabrication of a prototype 1m diameter engineering test unit (ETU) that will undergo a series of structural tests, characterizing material aerothermal performance including development of a material response model, and structural testing and analysis to develop tools to support design and establish system capability.

  17. GALILEO PROBE NMS RAW DATA SET

    Data.gov (United States)

    National Aeronautics and Space Administration — This Galileo Probe Mass Spectrometer (GPMS) data set includes: (1) Jupiter atmospheric entry data from December 7, 1995; (2) Instrument characterization data; March...

  18. The DISTO Data Acquisition System at SATURNE

    OpenAIRE

    The DISTO Collaboration

    1997-01-01

    The DISTO collaboration has built a large-acceptance magnetic spectrometer designed to provide broad kinematic coverage of multi-particle final states produced in $pp$ scattering. The spectrometer has been installed in the polarized proton beam of the Saturne accelerator in Saclay to study polarization observables in the $\\vec{p} p \\to p K^{+} \\vec{Y}$ ($Y = \\Lambda, \\Sigma^{0}$ or $Y^{*}$) reaction and vector meson production ($\\phi, \\omega$ and $\\rho$) in $pp$ collisions. The data acquisiti...

  19. Jovian-like aurorae on Saturn.

    Science.gov (United States)

    Stallard, Tom; Miller, Steve; Melin, Henrik; Lystrup, Makenzie; Cowley, Stan W H; Bunce, Emma J; Achilleos, Nicholas; Dougherty, Michele

    2008-06-19

    Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic field (although other processes form aurorae at both planets). At Saturn, only the main auroral oval has previously been observed and there remains much debate over its origin. Here we report the discovery of a secondary oval at Saturn that is approximately 25 per cent as bright as the main oval, and we show this to be caused by interaction with the middle magnetosphere around the planet. This is a weak equivalent of Jupiter's main oval, its relative dimness being due to the lack of as large a source of ions as Jupiter's volcanic moon Io. This result suggests that differences seen in the auroral emissions from Saturn and Jupiter are due to scaling differences in the conditions at each of these two planets, whereas the underlying formation processes are the same.

  20. The auroral footprint of Enceladus on Saturn.

    Science.gov (United States)

    Pryor, Wayne R; Rymer, Abigail M; Mitchell, Donald G; Hill, Thomas W; Young, David T; Saur, Joachim; Jones, Geraint H; Jacobsen, Sven; Cowley, Stan W H; Mauk, Barry H; Coates, Andrew J; Gustin, Jacques; Grodent, Denis; Gérard, Jean-Claude; Lamy, Laurent; Nichols, Jonathan D; Krimigis, Stamatios M; Esposito, Larry W; Dougherty, Michele K; Jouchoux, Alain J; Stewart, A Ian F; McClintock, William E; Holsclaw, Gregory M; Ajello, Joseph M; Colwell, Joshua E; Hendrix, Amanda R; Crary, Frank J; Clarke, John T; Zhou, Xiaoyan

    2011-04-21

    Although there are substantial differences between the magnetospheres of Jupiter and Saturn, it has been suggested that cryovolcanic activity at Enceladus could lead to electrodynamic coupling between Enceladus and Saturn like that which links Jupiter with Io, Europa and Ganymede. Powerful field-aligned electron beams associated with the Io-Jupiter coupling, for example, create an auroral footprint in Jupiter's ionosphere. Auroral ultraviolet emission associated with Enceladus-Saturn coupling is anticipated to be just a few tenths of a kilorayleigh (ref. 12), about an order of magnitude dimmer than Io's footprint and below the observable threshold, consistent with its non-detection. Here we report the detection of magnetic-field-aligned ion and electron beams (offset several moon radii downstream from Enceladus) with sufficient power to stimulate detectable aurora, and the subsequent discovery of Enceladus-associated aurora in a few per cent of the scans of the moon's footprint. The footprint varies in emission magnitude more than can plausibly be explained by changes in magnetospheric parameters--and as such is probably indicative of variable plume activity.

  1. Seeing ghosts - Photometry of Saturn's G Ring

    Science.gov (United States)

    Showalter, Mark R.; Cuzzi, Jeffrey N.

    1993-01-01

    Saturn's faint and narrow G Ring is only visible to the eye in two Voyager images, each taken at a rather high solar phase angle of about 160 deg. In this paper we introduce a new photometric technique for averaging across multiple Voyager images, and use it to detect the G Ring at several additional viewing geometries. The resultant phase curve suggests that the G Ring is composed of dust particles obeying a very steep power-law size distribution. The dust is generally smaller than that seen in other rings, ranging down to 0.03 micron. The G Ring occupies the region between orbital radii 166,000 and 173,000 km, and has a peak somewhat closer to the inner edge. Based on these limits, we demonstrate that Voyager 2 passed through and directly sampled this ring during its 1981 encounter with Saturn. Combined analysis of additional data sets suggests that a population of larger bodies is also present in the G Ring; these bodies occupy a narrower band near the observed peak and are likely the source for the visible dust. Based on some preliminary dynamical models, we propose that these larger bodies represent leftover debris from the collisional breakup of a small moon in Saturn's distant past.

  2. Whistler mode waves upstream of Saturn

    Science.gov (United States)

    Sulaiman, A. H.; Gurnett, D. A.; Halekas, J. S.; Yates, J. N.; Kurth, W. S.; Dougherty, M. K.

    2017-01-01

    Whistler mode waves are generated within and can propagate upstream of collisionless shocks. They are known to play a role in electron thermodynamics/acceleration and, under certain conditions, are markedly observed as wave trains preceding the shock ramp. In this paper, we take advantage of Cassini's presence at 10 AU to explore the importance of whistler mode waves in a parameter regime typically characterized by higher Mach number (median of 14) shocks, as well as a significantly different interplanetary magnetic field structure, compared to near Earth. We identify electromagnetic precursors preceding a small subset of bow shock crossings with properties which are consistent with whistler mode waves. We find these monochromatic, low-frequency, and circularly polarized waves to have a typical frequency range of 0.2-0.4 Hz in the spacecraft frame. This is due to the lower ion and electron cyclotron frequencies near Saturn, between which whistler waves can develop. The waves are also observed as predominantly right handed in the spacecraft frame, the opposite sense to what is typically observed near Earth. This is attributed to the weaker Doppler shift, owing to the large angle between the solar wind velocity and magnetic field vectors at 10 AU. Our results on the low occurrence of whistler waves upstream of Saturn also underpin the predominantly supercritical bow shock of Saturn.

  3. Entry at Venus

    Science.gov (United States)

    Venkatapathy, Ethiraj; Smith, Brandon

    2016-01-01

    This is lecture to be given at the IPPW 2016, as part of the 2 day course on Short Course on Destination Venus: Science, Technology and Mission Architectures. The attached presentation material is intended to be introduction to entry aspects of Venus in-situ robotic missions. The presentation introduces the audience to the aerodynamic and aerothermodynamic aspects as well as the loads, both aero and thermal, generated during entry. The course touches upon the system design aspects such as TPS design and both high and low ballistic coefficient entry system concepts that allow the science payload to be protected from the extreme entry environment and yet meet the mission objectives.

  4. Stratospheric benzene and hydrocarbon aerosols observed in Saturn's upper atmosphere

    Science.gov (United States)

    Guerlet, S.; Koskinen, T.

    2017-09-01

    We review recent observations of benzene and hydrocarbon aerosols in Saturn's middle and upper atmosphere by Cassini/CIRS and Cassini/UVIS. These results support the link between the precipitation of energetic electrons (ion chemistry) and the production of benzene and aerosols in Saturn's polar regions, and that solar-driven ion chemistry could also play a significant role in producing benzene at low and mid-latitudes. We also evaluate the radiative impact of the haze on Saturn's stratospheric temperatures.

  5. Optimisation of Code_Saturne for Petascale Simulations

    OpenAIRE

    Moulinec, C.

    2012-01-01

    Some of the optimisations required to prepare Code_Saturne for petascale simulations are presented in this white paper, along with the performance of the code. A mesh multiplication package based on parallel global refinement of hexahedral meshes has been developed for Code_Saturne to handle meshes containing billions† of cells and to efficiently exploit PRACE Tier-0 system capabilities. Several parallel partitioning tools have been tested and Code_Saturne performance has been assessed up to ...

  6. The CIRS Investigation on Cassini after Six Years at Saturn

    Science.gov (United States)

    Jennings, Donald

    2010-01-01

    The CIRS investigation designed to provide: 1) infrared spectroscopy of thermal emission from atmospheres, rings, and surfaces in 10 +/- 1450 cm(exp -1) (1000 +/- 7 micron) region; 2) global mapping in atmospheres of three dimensional and temporal variation of gas composition, temperatures, dynamics, and aerosols and clouds; and 3) mapping of rings and icy satellite surfaces for composition and thermal properties. Topics include: optical and mechanical layouts, instrument description, preparation for launch, Saturn's rings in the light spectrum, Saturn brightness temperature spectrum, and views of Saturn's surface, rings, and Saturn's moons and their atmospheres.

  7. Correction terms for the thermodynamics of a black Saturn

    Energy Technology Data Exchange (ETDEWEB)

    Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Pourhassan, Behnam, E-mail: b.pourhassan@du.ac.ir [School of Physics, Damghan University, Damghan (Iran, Islamic Republic of)

    2015-12-17

    In this paper, we will analyze the effects of thermal fluctuations on the stability of a black Saturn. The entropy of the black Saturn will get corrected due to these thermal fluctuations. We will demonstrate that the correction term generated by these thermal fluctuations is a logarithmic term. Then we will use this corrected value of the entropy to obtain bounds for various parameters of the black Saturn. We will also analyze the thermodynamical stability of the black Saturn in presence of thermal fluctuations, using this corrected value of the entropy.

  8. Corrections Terms for the Thermodynamics of a Black Saturn

    CERN Document Server

    Faizal, Mir

    2015-01-01

    In this paper, we will analyze the effects of thermal fluctuations on the stability of a black Saturn. The entropy of the black Saturn will get corrected due to these thermal fluctuations. We will demonstrate that the correction term generated by these thermal fluctuations is a logarithmic term. Then we will use this corrected value of the entropy to obtain bounds for various parameters of the black Saturn. We will also analyze the thermodynamical stability of the black Saturn in presence of thermal fluctuations, using this corrected value of the entropy.

  9. Density Structures, Dynamics, and Seasonal and Solar Cycle Modulations of Saturn's Inner Plasma Disk

    Science.gov (United States)

    Holmberg, M. K. G.; Shebanits, O.; Wahlund, J.-E.; Morooka, M. W.; Vigren, E.; André, N.; Garnier, P.; Persoon, A. M.; Génot, V.; Gilbert, L. K.

    2017-12-01

    We present statistical results from the Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe measurements recorded during the time interval from orbit 3 (1 February 2005) to 237 (29 June 2016). A new and improved data analysis method to obtain ion density from the Cassini LP measurements is used to study the asymmetries and modulations found in the inner plasma disk of Saturn, between 2.5 and 12 Saturn radii (1 RS=60,268 km). The structure of Saturn's plasma disk is mapped, and the plasma density peak, nmax, is shown to be located at ˜4.6 RS and not at the main neutral source region at 3.95 RS. The shift in the location of nmax is due to that the hot electron impact ionization rate peaks at ˜4.6 RS. Cassini RPWS plasma disk measurements show a solar cycle modulation. However, estimates of the change in ion density due to varying EUV flux is not large enough to describe the detected dependency, which implies that an additional mechanism, still unknown, is also affecting the plasma density in the studied region. We also present a dayside/nightside ion density asymmetry, with nightside densities up to a factor of 2 larger than on the dayside. The largest density difference is found in the radial region 4 to 5 RS. The dynamic variation in ion density increases toward Saturn, indicating an internal origin of the large density variability in the plasma disk rather than being caused by an external source origin in the outer magnetosphere.

  10. Double entry bookkeeping vs single entry bookkeeping

    Directory of Open Access Journals (Sweden)

    Ileana Andreica

    2016-11-01

    Full Text Available Abstract: A financial management eficiently begin, primarily, with an accounting record kept in the best possible conditions, this being conditioned on the adoption of a uniform forms, rational, clear and simple accounting. Throughout history, there have been known two forms of accounting: the simple and double entry. Romanian society after 1990 underwent a substantial change in social structure, the sector on which put a great emphasis being private, that of small manufacturers, peddler, freelance, who work independently and authorized or as associative form (family enterprises, various associations (owners, tenants, etc., liberal professions, etc.. They are obliged to keep a simple bookkeeping, because they have no juridical personality. Companies with legal personality are required to keep double entry bookkeeping; therefore, knowledge and border demarcation between the two forms of organisation of accounting is an essential. The material used for this work is mainly represented by the financial and accounting documents, by the analysis of the economic, by legislative updated sources, and as the method was used the comparison method, using hypothetical data, in case of an authorized individual and a legal entity. Based on the chosen material, an authorized individual (who perform single entry accounting system and a juridical entity (who perform double entry accounting system were selected comparative case studies, using hypothetical data, were analysed advantages and disadvantages in term of fiscal, if using two accounting systems, then were highlighted some conclusion that result.

  11. Entry Skills for BSNs.

    Science.gov (United States)

    Stull, Mary K.

    1986-01-01

    Describes the Continuing Education for Consensus on Entry Skills project, designed to bring the expectations of nursing service and nursing education closer on entry-level competencies of new baccalaureate graduates. Discusses teaching and collaboration skills, planning and evaluation of patient care skills, interpersonal relations/communication…

  12. Atmospheric Entry Experiments at IRS

    Science.gov (United States)

    Auweter-Kurtz, M.; Endlich, P.; Herdrich, G.; Kurtz, H.; Laux, T.; Löhle, S.; Nazina, N.; Pidan, S.

    2002-01-01

    simulations. PHLUX: Based on experiences with PYREX, a sensor for heat flux measurements is being developed at IRS. This experiment is to estimate the dissociation degree during a entry using measured heat fluxes on different catalytic sur- faces. Such information are of importance for the understanding of thermo-chemical relation between plasma and TPS wall. The sensor delivers heat fluxes at wall temperature while most of the existing heat flux measurement systems use heat sink based methodologies meaning that temperatures on these sensors are not the real wall temperatures. Such measurements were planned in the PYREX-KAT38 (X-38) program but had to be set back due to problems with the foreseen catalytic surfaces. Boundary Layer Probe is to determine the boundary layer thickness and pressure. The retractable probe is used to measure the pressure in the flight body boundary layer perpendicular to the material surface. The pressure curve can be used to determine the position and thickness of the shock front. Radiometer: With high enthalpy entries and many interplanetary missions such as missions to Mars or Venus, the radiative portion of the heat flux to a vehicle cannot be neglected. High enthalpy and radiative intensities of some car- bonaceous molecules cause high radiation intensities which is, e.g., the case for the Huygens mission. At IRS, the heat shield material for Huygens was tested and the qualification was carried out. Within this context a radiometer probe for wind tunnel application was developed.

  13. Saturn Ring Seismology: Evidence for Stable Stratification in the Deep Interior of Saturn

    Science.gov (United States)

    Fuller, J.

    2014-12-01

    Seismology allows for direct observational constraints on the interior structures of stars and planets. Recent observations of Saturn's ring system have revealed the presence of density waves within the rings excited by oscillation modes within Saturn, allowing for precise measurements of a limited set of the planet's mode frequencies. We construct interior structure models of Saturn, compute the corresponding mode frequencies, and compare them with the observed mode frequencies. The fundamental mode frequencies of our models match the observed frequencies (of the largest amplitude waves) to an accuracy of roughly 1%, confirming that these waves are indeed excited by Saturn's f-modes. The presence of the lower amplitude waves (finely split in frequency from the f-modes) can only be reproduced in models containing gravity modes that propagate in a stably stratified region of the planet. The stable stratification must exist deep within the planet near the large density gradients between the core and envelope. Our models cannot easily reproduce the observed fine splitting of the m=3 modes, suggesting that additional effects (e.g., significant latitudinal differential rotation) may be important.

  14. Mysterious Saturn--Some Ancient and Modern Views

    Science.gov (United States)

    Agarwal, Pankaj

    2011-01-01

    The familiar image of Saturn and its rings has come to symbolise our idea of a planet but there is still much about Saturn and its system that we do not understand. The history of our beliefs and knowledge about it, one of the most distant planets visible to the naked eye, is described, from the early myths, such as the Indian village that…

  15. X-Rays from Saturn and its Rings

    Science.gov (United States)

    Bhardwaj, Anil; Elsner, Ron F.; Waite, J. Hunter; Gladstone, G. Randall; Cravens, Tom E.; Ford, Peter G.

    2005-01-01

    In January 2004 Saturn was observed by Chandra ACIS-S in two exposures, 00:06 to 11:00 UT on 20 January and 14:32 UT on 26 January to 01:13 UT on 27 January. Each continuous observation lasted for about one full Saturn rotation. These observations detected an X-ray flare from the Saturn's disk and indicate that the entire Saturnian X-ray emission is highly variable -- a factor of $\\sim$4 variability in brightness in a week time. The Saturn X-ray flare has a time and magnitude matching feature with the solar X-ray flare, which suggests that the disk X-ray emission of Saturn is governed by processes happening on the Sun. These observations also unambiguously detected X-rays from Saturn's rings. The X-ray emissions from rings are present mainly in the 0.45-0.6 keV band centered on the atomic OK$\\alpha$ fluorescence line at 525 eV: indicating the production of X-rays due to oxygen atoms in the water icy rings. The characteristics of X-rays from Saturn's polar region appear to be statistically consistent with those from its disk X-rays, suggesting that X-ray emission from the polar cap region might be an extension of the Saturn disk X-ray emission.

  16. Thermal Infrared Spectroscopy of Saturn and Titan from Cassini

    Science.gov (United States)

    Jennings, Donald E.; Brasunas, J. C.; Carlson, R. C.; Flasar, F. M.; Kunde, V. G.; Mamoutkine, A. A.; Nixon, A.; Pearl, J. C.; Romani, P. N.; Simon-Miller, A. A.; hide

    2009-01-01

    The Cassini spacecraft completed its nominal mission at Saturn in 2008 and began its extended mission. Cassini carries the Composite Infrared Spectrometer (CIRS); a Fourier transform spectrometer that measures the composition, thermal structure and dynamics of the atmospheres of Saturn and Titan, and also the temperatures of other moons and the rings.

  17. In Situ Surveying of Saturn's Rings

    Science.gov (United States)

    Clark, P. E.; Curtis, S. A.; Rilee, M. L.; Cheung, C.

    2004-01-01

    The Saturn Autonomous Ring Array (SARA) mission concept is a new application for the Autonomous Nano-Technology Swarm (ANTS) architecture, a paradigm being developed for exploration of high surface area and/or multibody targets to minimize costs and maximize effectiveness of survey operations. Systems designed with ANTS architecture are built from potentially very large numbers of highly autonomous, yet socially interactive, specialists, in approximately ten specialist classes. Here, we analyze requirements for such a mission as well as specialized autonomous operations which would support this application.

  18. A photometric study of Saturn's F Ring

    Science.gov (United States)

    Showalter, Mark R.; Pollack, James B.; Ockert, Maureen E.; Doyle, Laurance R.; Dalton, J. B.

    1992-01-01

    The Saturn F Ring's radially integrated brightness has been measured over a wide range of phase angles from Voyager images; in order to model the resultant phase curve, the ring population has been divided into a dust regime and one of larger bodies, and while single scattering properties of small particles are modeled by semiempirical nonspherical/randomly oriented particles, those of large bodies are based on the photometric behavior of satellites. It is suggested that the dust in the envelope arises from micrometeoroid impacts into the large core particles, and then migrates inward.

  19. The fractal theory of the Saturn Ring

    OpenAIRE

    Zelikin, Mikhail

    2015-01-01

    The true reason for partition of the Saturn ring as well as rings of other planets into great many of sub-rings is found. This reason is the theorem of Zelikin-Lokutsievskiy-Hildebrand about fractal structure of solutions to generic piece-wise smooth Hamiltonian systems. The instability of two-dimensional model of rings with continues surface density of particles distribution is proved both for Newtonian and for Boltzmann equations. We do not claim that we have solved the problem of stability...

  20. Oxygen ions observed near Saturn's A ring.

    Science.gov (United States)

    Waite, J H; Cravens, T E; Ip, W-H; Kasprzak, W T; Luhmann, J G; McNutt, R L; Niemann, H B; Yelle, R V; Mueller-Wodarg, I; Ledvina, S A; Scherer, S

    2005-02-25

    Ions were detected in the vicinity of Saturn's A ring by the Ion and Neutral Mass Spectrometer (INMS) instrument onboard the Cassini Orbiter during the spacecraft's passage over the rings. The INMS saw signatures of molecular and atomic oxygen ions and of protons, thus demonstrating the existence of an ionosphere associated with the A ring. A likely explanation for these ions is photoionization by solar ultraviolet radiation of neutral O2 molecules associated with a tenuous ring atmosphere. INMS neutral measurements made during the ring encounter are dominated by a background signal.

  1. Infrared thermal models for Saturn's ring

    Science.gov (United States)

    Price, M. J.

    1976-01-01

    Infrared (10 and 20 microns) thermal emission data for Saturn's rings are discussed in terms of simple isothermal radiative transfer models of finite optical thickness. Recent brightness temperature measurements, corresponding to essentially maximum ring tilt, indicate that optical single scattering albedos less than 0.75 are required to provide sufficient heating of the ring material. Reconciliation with analyses of the optical scattering properties of the ring requires the backscattering efficiency to be even higher than for a macroscopic sphere. Historical brightness temperature measurements are used to show that no unique isothermal ring model exists. Instead, a temperature gradient perpendicular to the ring plane appears to be present.

  2. First determination of the tropospheric CO abundance in Saturn

    Science.gov (United States)

    Fouchet, Thierry; Lellouch, Emmanuel; Cavalié, Thibault; Bézard, Bruno

    2017-10-01

    In Giant Planets, CO has two potential origins: i) an external source in form of cometary impacts, infalling ring/satellite dust or/and interplanetary particles; ii) an internal origin that involves convective transport from the deep, dense, hot atmosphere where the thermodynamic equilibrium CO abundance is relatively large.In Saturn, submilimeter stratospheric CO emissions have been detected (Cavalié et al. A&A, 510, A88, 2010; Cavalié et al. Icarus, 203, 531, 2009), suggesting a cometary impact 200 years ago. In contrast, no observation was in position to confirm or rule out the presence of CO in Saturn's troposphere (Noll et al. Icarus, 89, 168, 1990).Here, we present CRIRES/ELT 5-μm observations of Saturn that definitely confirm the presence of CO in Saturn's troposphere. We will present the derived CO abundance and its implication for Saturn's tropospheric transport rate and water deep abundance.

  3. Compositional maps of Saturn's moon Phoebe from imaging spectroscopy.

    Science.gov (United States)

    Clark, Roger N; Brown, Robert H; Jaumann, Ralf; Cruikshank, Dale P; Nelson, Robert M; Buratti, Bonnie J; McCord, Thomas B; Lunine, J; Baines, K H; Bellucci, G; Bibring, J-P; Capaccioni, F; Cerroni, P; Coradini, A; Formisano, V; Langevin, Y; Matson, D L; Mennella, V; Nicholson, P D; Sicardy, B; Sotin, C; Hoefen, Todd M; Curchin, John M; Hansen, Gary; Hibbits, Karl; Matz, K-D

    2005-05-05

    The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, circular orbits) probably accreted within the sub-nebula in which Saturn itself formed. Here we report imaging spectroscopy of Phoebe resulting from the Cassini-Huygens spacecraft encounter on 11 June 2004. We mapped ferrous-iron-bearing minerals, bound water, trapped CO2, probable phyllosilicates, organics, nitriles and cyanide compounds. Detection of these compounds on Phoebe makes it one of the most compositionally diverse objects yet observed in our Solar System. It is likely that Phoebe's surface contains primitive materials from the outer Solar System, indicating a surface of cometary origin.

  4. The electron density of Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    M. W. Morooka

    2009-07-01

    Full Text Available We have investigated statistically the electron density below 5 cm−3 in the magnetosphere of Saturn (7–80 RS, Saturn radii using 44 orbits of the floating potential data from the RPWS Langmuir probe (LP onboard Cassini. The density distribution shows a clear dependence on the distance from the Saturnian rotation axis (√X2+Y2 as well as on the distance from the equatorial plane (|Z|, indicating a disc-like structure. From the characteristics of the density distribution, we have identified three regions: the extension of the plasma disc, the magnetodisc region, and the lobe regions. The plasma disc region is at L<15, where L is the radial distance to the equatorial crossing of the dipole magnetic field line, and confined to |Z|<5 RS. The magnetodisc is located beyond L=15, and its density has a large variability. The variability has quasi-periodic characteristics with a periodicity corresponding to the planetary rotation. For Z>15 RS, the magnetospheric density distribution becomes constant in Z. However, the density still varies quasi-periodically with the planetary rotation also in this region. In fact, the quasi-periodic variation has been observed all over the magnetosphere beyond L=15. The region above Z=15 RS is identified as the lobe region. We also found that the magnetosphere can occasionally move latitudinally under the control of the density in the magnetosphere and the solar wind. From the empirical distributions of the electron densities obtained in this study, we have constructed an electron density model of the Saturnian nightside magnetosphere beyond 7 RS. The obtained model can well reproduce the observed density distribution, and can thus be useful for magnetospheric modelling studies.

  5. Border Crossing Entry Data

    Data.gov (United States)

    Department of Transportation — The Bureau of Transportation Statistics (BTS) Border Crossing/Entry Data provides summary statistics for inbound crossings at the U.S.-Canadian and the U.S.-Mexican...

  6. Source mechanism of Saturn narrowband emission

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2010-04-01

    Full Text Available Narrowband emission (NB is observed at Saturn centered near 5 kHz and 20 kHz and harmonics. This emission appears similar in many ways to Jovian kilometric narrowband emission observed at higher frequencies, and therefore may have a similar source mechanism. Source regions of NB near 20 kHz are believed to be located near density gradients in the inner magnetosphere and the emission appears to be correlated with the occurrence of large neutral plasma clouds observed in the Saturn magnetotail. In this work we present the results of a growth rate analysis of NB emission (~20 kHz near or within a probable source region. This is made possible by the sampling of in-situ wave and particle data. The results indicate waves are likely to be generated by the mode-conversion of directly generated Z-mode emission to O-mode near a density gradient. When the local hybrid frequency is close n fce (n is an integer and fce is the electron cyclotron frequency with n=4, 5 or 6 in our case, electromagnetic Z-mode and weak ordinary (O-mode emission can be directly generated by the cyclotron maser instability.

  7. Cassini Can Constrain Tidal Dissipation in Saturn

    Science.gov (United States)

    Luan, Jing; Fuller, Jim; Quataert, Eliot

    2017-10-01

    Tidal dissipation inside giant planets is important for the orbital evolution of their natural satellites. It is conventionally treated by parameterized equilibrium tidal the- ory, in which the tidal torque declines rapidly with distance, and orbital expansion was faster in the past. However, Lainey et al. (2017) find that some Saturnian satellites are currently migrating outward faster than predicted by equilibrium tidal theory. Reso- nance locking between satellites and internal oscillations of Saturn, proposed by Fuller et al. (2016), naturally matches the observed migration rates. Here, we show that the resonance locking theory predicts dynamical tidal perturbations to Saturn’s gravita- tional field in addition to those produced by equilibrium tidal bulges. We show that these perturbations can likely be detected during Cassini’s proximal orbits if migra- tion of satellites results from resonant gravity modes, but will likely be undetectable if migration results from inertial wave attractors or dissipation of the equilibrium tide. Additionally, we show that the detection of gravity modes would place constraints on the size of the hypothetical stably stratified region in Saturn.

  8. Source mechanism of Saturn narrowband emission

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2010-04-01

    Full Text Available Narrowband emission (NB is observed at Saturn centered near 5 kHz and 20 kHz and harmonics. This emission appears similar in many ways to Jovian kilometric narrowband emission observed at higher frequencies, and therefore may have a similar source mechanism. Source regions of NB near 20 kHz are believed to be located near density gradients in the inner magnetosphere and the emission appears to be correlated with the occurrence of large neutral plasma clouds observed in the Saturn magnetotail. In this work we present the results of a growth rate analysis of NB emission (~20 kHz near or within a probable source region. This is made possible by the sampling of in-situ wave and particle data. The results indicate waves are likely to be generated by the mode-conversion of directly generated Z-mode emission to O-mode near a density gradient. When the local hybrid frequency is close n fce (n is an integer and fce is the electron cyclotron frequency with n=4, 5 or 6 in our case, electromagnetic Z-mode and weak ordinary (O-mode emission can be directly generated by the cyclotron maser instability.

  9. Doppler effects on periodicities in Saturn's magnetosphere

    Science.gov (United States)

    Carbary, J. F.

    2015-11-01

    The magnetosphere of Saturn exhibits a wide variety of periodic phenomena in magnetic fields, charged particles, and radio emissions. The periodicities are observed from a moving spacecraft, so an issue arises about the periodicities being influenced by the Doppler effects. Doppler effects can be investigated using models of the periodicities and then flying the spacecraft through the model, effectively measuring any Doppler phenomena with the simulation. Using 200 days of typical elliptical orbits from the Cassini mission at Saturn, three models were tested: an azimuthal wave (or "searchlight") model, a radial wave (or "pond ripple") model, and a model of an outwardly traveling spiral wave. The azimuthal wave model produced virtually no Doppler effects in the periodicities because its wave vector is nearly perpendicular to the spacecraft trajectory. The radial wave model generated strong Doppler effects of an upshifted and a downshifted signal (a dual period) on either side of the true period, because the wave vector is either parallel or antiparallel to the spacecraft trajectory. Being intermediate to the searchlight and radial waves, the spiral wave produced Doppler effects but only for low wave speeds (<10 RS/h). For higher wave speeds the Doppler effects were not as clear. The Doppler effects can be mitigated by employing only observations beyond ~15 RS where the spacecraft speed is low compared to the wave speed. The observed periodicities over the same 200 day interval do not show evidence of Doppler effects but generally display a single feature at the expected ~10.7 h period.

  10. Saturn's Inner Satellites at True Opposition

    Science.gov (United States)

    Verbiscer, Anne

    2004-07-01

    We request one HST orbit to observe Janus, Epimetheus, Mimas, and Enceladus with WFPC2 exactly at opposition, when the Earth transits the center of the solar disk seen from Saturn on UT 13/14 January 2005. Data obtained at this unique viewing geometry are essential to determining physical properties of the moon's surface, related to its emplacement and evolution, and critical for the interpretation of photometric data obtained by Cassini at higher phase angles. This single observation will be the capstone of 9 years of legacy HST WFPC2 observations of the saturnian system {Cycles 6-12, R. French, PI} from which we have constructed precise, multiwavelength phase curves which demonstrate how the reflectance of these satellites varies with solar phase angle from 0.07 to 6.4 degrees. Each satellite exhibits a dramatic increase in brightness, or "opposition effect", as phase angles decrease below 1 degree. Since 1998 {Cycle 7} the minimum observable phase angle at opposition has decreased each year to 0.07 degrees in Cycle 12; however, the absolute minimum observable phase angle, about 0.02 degrees {limited by the angular size of the Sun viewed from Saturn}, has not been accessible until Cycle 13. Using the same set of broadband filters for continuity with our previous programs, we will place observations made during the Earth transit on the existing UVBRI phase curves and establish the amplitude of each satellite's opposition surge. From these observations we will determine surface properties such as porosity, grain size distribution and particle opacity using radiative transfer models. While the Cassini spacecraft will obtain images at larger phase angles, it will miss entirely the narrow brightness surge near opposition due to orbital constraints. Because these inner satellites will be either lost in or contaminated by the glare of the fully open rings, they are not accessible to ground-based telescopes. The 2005 opposition prese nts the only opportunity for HST to

  11. Effect of thermal fluctuations on a charged dilatonic black Saturn

    Directory of Open Access Journals (Sweden)

    Behnam Pourhassan

    2016-04-01

    Full Text Available In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  12. Effect of thermal fluctuations on a charged dilatonic black Saturn

    Energy Technology Data Exchange (ETDEWEB)

    Pourhassan, Behnam, E-mail: b.pourhassan@du.ac.ir [School of Physics, Damghan University, Damghan (Iran, Islamic Republic of); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada)

    2016-04-10

    In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  13. The Saturn System Through the Eyes of Cassini

    Science.gov (United States)

    Green, James

    2017-01-01

    More than 400 years ago, Galileo Galilei trained his homemade telescope on the night sky and observed that Saturn had two objects closely related to the planet extending on either side. At the time, in 1610, Galileo declared them to be moons. A few decades later, Saturn moon science accelerated at a dizzying pace. Christiaan Huygens first observed Saturn's largest moon Titan in 1655 and was the first to describe the extended moon-like features at Saturn as a disk of material sounding the planet. From 1671 to 1674, Giovanni Cassini discovered the moons lapetus, Rhea, Dione and Tethys. In 1675, Cassini discovered the gap in Saturn's rings that we now know as the Cassini Division. In the space age, before the Cassini-Huygens mission, we had only hints of the discoveries awaiting us at Saturn. Pioneer 11 and Voyagers 1 and 2 conducted flybys decades ago. But these quick encounters didn't allow time for more extensive research. NASA and the European Space Agency created a partnership to orbit a Saturn orbiter (Cassini) and a lander (Huygens) on Titan. Like its namesakes, the Cassini-Huygens mission not only discovered previously unknown moons, but it also helped us understand the science behind their formation, their interactions with the rings, and how truly diverse they are. The Cassini-Huygens mission revolutionized what we know about the Saturn system. The rings of Saturn, the moons, and the planet itself offer irresistible and inexhaustible subjects for intense study, and Cassini-Huygens did not disappoint. The Saturnian system proved to be a rich ground for science exploration and discoveries, and Cassini has been nothing short of a discovery machine. At the time Cassini plunged into Saturn at the end of its mission, it had observed the planet for a little less than half of a Saturn year. But it also orbited the gas giant 293 times, forever changing our understanding of the Saturn system and yielding tremendous insight for understanding the entire Solar System.

  14. Cassini Imaging Science: initial results on Saturn's atmosphere.

    Science.gov (United States)

    Porco, C C; Baker, E; Barbara, J; Beurle, K; Brahic, A; Burns, J A; Charnoz, S; Cooper, N; Dawson, D D; Del Genio, A D; Denk, T; Dones, L; Dyudina, U; Evans, M W; Giese, B; Grazier, K; Helfenstein, P; Ingersoll, A P; Jacobson, R A; Johnson, T V; McEwen, A; Murray, C D; Neukum, G; Owen, W M; Perry, J; Roatsch, T; Spitale, J; Squyres, S; Thomas, P; Tiscareno, M; Turtle, E; Vasavada, A R; Veverka, J; Wagner, R; West, R

    2005-02-25

    The Cassini Imaging Science Subsystem (ISS) began observing Saturn in early February 2004. From analysis of cloud motions through early October 2004, we report vertical wind shear in Saturn's equatorial jet and a maximum wind speed of approximately 375 meters per second, a value that differs from both Hubble Space Telescope and Voyager values. We also report a particularly active narrow southern mid-latitude region in which dark ovals are observed both to merge with each other and to arise from the eruptions of large, bright storms. Bright storm eruptions are correlated with Saturn's electrostatic discharges, which are thought to originate from lightning.

  15. Effect of Thermal Fluctuations on a Charged Dilatonic Black Saturn

    CERN Document Server

    Pourhassan, Behnam

    2016-01-01

    In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  16. Identification of Saturn's magnetospheric regions and associated plasma processes: Synopsis of Cassini observations during orbit insertion

    OpenAIRE

    Andre, N; Blanc, M; Maurice, S.; Schippers, P.; Pallier, E.; Gombosi, T. I.; Hansen, K. C.; Young, D. T.; Crary, F. J.; Bolton, S; Sittler, E. C.; Smith, H.T.; Johnson, R E; Baragiola, R. A.; Coates, A J

    2008-01-01

    Saturn's magnetosphere is currently studied from the microphysical to the global scale by the Cassini-Huygens mission. During the first half of 2004, in the approach phase, remote sensing observations of Saturn's magnetosphere gave access to its auroral, radio, UV, energetic neutral atom, and dust emissions. Then, on 1 July 2004, Cassini Saturn orbit insertion provided us with the first in situ exploration of Saturn's magnetosphere since Voyager. To date, Saturn orbit insertion is the only Ca...

  17. Outreach for Cassini Huyghens mission and future Saturn and Titan exploration: From the Antikythera Mechanism to the TSSM mission

    Science.gov (United States)

    Moussas, Xenophon; Bampasidis, Georgios; Coustenis, Athena; Solomonidou, Anezina

    2010-05-01

    These days Outreach is an activity tightly related to success in science. The public with its great interest to space and astronomy in general, the solar system exploration and Saturn and Titan in particular, loves the scientific outcome of Cassini and Huygens. This love of the public gives a lot, as its known interest to space, persuades politicians and policy makers to support space and future Saturn and Titan explorations. We use the scientific results from Cassini and Huyghens together with a mosaic from ancient science concerning the history of solar system exploration, such as the oldest known complex astronomical device, the Antikyhtera Mechanism, in outreach activities to ensure future missions and continuous support to present ones. A future mission to the Saturnian System focusing on exotic Titan will broaden people's interest not only to Physics and Astronomy, but to Mechanics, Technology and even Philosophy as well, since, obviously, the roots of the vast contribution of Space Science and Astronomy to the contemporary society can be traced back to the first astronomers of Antiquity. As an example we use the Antikythera Mechanism, a favourite astronomical device for the public, which is the first geared astronomical device ever, constructed that combines the spirit of the ancient Astronomy and scientific accuracy. It is common belief that Astronomy and Astrophysics is a perfect tool to easily involve people in Science, as the public is always interested in space subjects, captivated by the beauty and the mystery of the Universe. Years after the successful entry, descent and landing of the Huygens probe on Titan's surface, the outstanding achievements of the Cassini-Huygens mission enhance the outreach potential of Space Science. Titan is an earth-like world, embedded in a dense nitrogen atmospheric envelop and a surface carved by rivers, mountains, dunes and lakes, its exploration will certainly empower the perspective of the society for space activities

  18. Pickering Membranes Stabilized by Saturn Particles.

    Science.gov (United States)

    Krejca, Matthias M; Wüstner, Cornell; Goedel, Werner A

    2017-10-17

    We report on a novel method to synthesize particles-called by us Saturn particles-having two hydrophobic caps that oppose each other and are separated from each other by a hydrophilic belt that encircles the particle. Mixtures of these particles with water and air, without the usage of low molar mass surfactants, easily form Pickering foams and Pickering membranes that are stable for days. These Pickering membranes are composed of a thin film of water into which the particles are embedded in such a way that the belt is surrounded by the water and the caps protrude out of the water into the air at the top and bottom side of the water film. As expected for a liquid membrane, these Pickering membranes are permeable for gases, with the permeance being proportional to the solubility and diffusion coefficient of the gas considered. Experimentally obtained permeance values agree reasonably well with theoretical calculations.

  19. Very energetic protons in Saturn's radiation belt

    Science.gov (United States)

    Fillius, W.; Mcilwain, C.

    1980-01-01

    Very energetic protons are trapped in the inner Saturnian radiation belt. The University of California at San Diego instrument on Pioneer 11 has definitely identified protons of energy greater than 80 MeV on channel M3 and has tentatively detected protons of energy greater than 600 MeV on channel C3. The spatial distribution of the protons is distinct from that of the trapped electrons, the main difference being that the protons are strongly absorbed by the innermost moons and that the electrons are not. The source strength for injecting protons by the decay of cosmic ray albedo neutrons generated in the rings of Saturn has been estimated. The required proton lifetime is approximately 20 years.

  20. Voyager Photometry of Saturn's A Ring

    Science.gov (United States)

    Dones, Luke; Cuzzi, Jeffrey N.; Showalter, Mark R.

    1993-01-01

    Saturn's A Ring samples a wide range of dynamical environments, from the relatively unperturbed, optically thick inner region to the outer part of the ring, which contains numerous density waves. We analyze Voyager images of the A Ring to determine how the reflectivity of different radial regions varies with lighting and viewing geometry. We model our data with a classical radiative transfer code that includes the illumination of the rings by the Sun and Saturn. The particles in the inner and mid-A Ring have Bond albedos near 0.5 and are more backscattering than satellites of comparable albedo. The region outside the Encke Gap becomes progressively less backscattering with increasing radius. Particle properties change abruptly outside the Keeler Gap; particles here have an albedo near 0.6 and a Lambert-like phase function. In contrast with previous suggestions, the abundance of free, submicrometer "dust" is small throughout the entire A Ring; this conclusion holds even in the outermost A Ring, which is strongly perturbed by density waves. Models derived from low-phase data, assuming only macroscopic particles, correctly predict the highphase reflectivity of the outer A Ring and individual strong density waves in the mid-A Ring. However, the inner and mid-A Ring are typically darker at high phase by a factor of two than our models predict. This discrepancy may be due to the reduced multiple scattering from a layer in which the particles are more closely packed. We have also studied the quadrupole azimuthal brightness asymmetry of the A Ring. The asymmetry has a full amplitude of 35% in the mid-A Ring in low-phase Voyager 2 images. We present results on its behavior and possible implications for the structure of the rings. Finally, we compare our results with studies using other data sets to synthesize our current understanding of the nature of the A Ring.

  1. Viral Entry into Cells

    Science.gov (United States)

    D'Orsogna, Maria R.

    2010-09-01

    Successful viral infection of a healthy cell requires complex host-pathogen interactions. In this talk we focus on the dynamics specific to the HIV virus entering a eucaryotic cell. We model viral entry as a stochastic engagement of receptors and coreceptors on the cell surface. We also consider the transport of virus material to the cell nucleus by coupling microtubular motion to the concurrent biochemical transformations that render the viral material competent for nuclear entry. We discuss both mathematical and biological consequences of our model, such as the formulation of an effective integrodifferential boundary condition embodying a memory kernel and optimal timing in maximizing viral probabilities.

  2. IR spectra of Saturn's ring spokes and multiple shines in the Saturn-rings system

    Science.gov (United States)

    D'Aversa, Emiliano; Bellucci, Giancarlo; Filacchione, Gianrico; Cerroni, Priscilla; Nicholson, Phil D.; Carrozzo, Filippo G.; Altieri, Francesca; Oliva, Fabrizio; Geminale, Anna; Sindoni, Giuseppe; Hedman, Matthew M.

    2017-04-01

    During the last Saturn equinox, in 2009 August, spokes on the Saturn's B ring have been observed for the first time spectroscopically, at visible and infrared wavelengths. Measurements were obtained by Cassini-VIMS (Visual and Infrared Mapping Spectrometer) instrument in the 0.35-5.1 micron range. Spokes are either dark or bright features appearing on the B ring straddling the equinoxes, round to elongated in shape, lasting for minutes to hours, and moving partially pushed by Saturn's magnetic field. Previous spokes observations date back to the Voyager (1980 equinox,[1]), followed by a HST campaign (1995 equinox,[2]), and more recently Cassini-ISS images (2009 equinox,[3]). Theoretical models of spoke formation and evolution have been developed based on those observations, but there is not unanimous consensus on them. The most spread model considers the spoke as a cloud of very fine particles electrostatically levitating from the regolith of ring's boulders, and hovering on the ring plane while interacting with the ambient plasma until complete charge neutralization. The process triggering the grain charging is not yet clear (meteoroid bombardment, impacts of Saturn's lightnings electrons, etc.) but in any case a very small grain mass (high charge-to-mass ratio) is needed to allow electrostatic repulsion. From the observational point of view, small grain sizes (0.3-0.5 micron) have been retrieved by modeling the spoke reflectance in the visible spectral range (both Voyager, HST, and Cassini were equipped with multispectral imaging cameras). However, a first VIMS spoke observation ([4]) inferred a more spread size distribution (0.3 to 2.5 microns) to explain the high spoke contrast measured in the infrared. Here we will report about an analysis of two selected sets of spokes observed by VIMS. This selection aimed to include both high and low phase angle observations, and to take advantage from the highest spatial resolution data achieved in the infrared. We will

  3. Noncircular features in Saturn's rings IV: Absolute radius scale and Saturn's pole direction

    Science.gov (United States)

    French, Richard G.; McGhee-French, Colleen A.; Lonergan, Katherine; Sepersky, Talia; Jacobson, Robert A.; Nicholson, Philip D.; Hedman, Mathew M.; Marouf, Essam A.; Colwell, Joshua E.

    2017-07-01

    We present a comprehensive solution for the geometry of Saturn's ring system, based on orbital fits to an extensive set of occultation observations of 122 individual ring edges and gaps. We begin with a restricted set of very high quality Cassini VIMS, UVIS, and RSS measurements for quasi-circular features in the C and B rings and the Cassini Division, and then successively add suitably weighted additional Cassini and historical occultation measurements (from Voyager, HST and the widely-observed 28 Sgr occultation of 3 Jul 1989) for additional non-circular features, to derive an absolute radius scale applicable across the entire classical ring system. As part of our adopted solution, we determine first-order corrections to the spacecraft trajectories used to determine the geometry of individual occultation chords. We adopt a simple linear model for Saturn's precession, and our favored solution yields a precession rate on the sky n^˙P = 0.207 ± 0 .006‧‧yr-1 , equivalent to an angular rate of polar motion ΩP = 0.451 ± 0 .014‧‧yr-1 . The 3% formal uncertainty in the fitted precession rate is approaching the point where it can provide a useful constraint on models of Saturn's interior, although realistic errors are likely to be larger, given the linear approximation of the precession model and possible unmodeled systematic errors in the spacecraft ephemerides. Our results are largely consistent with independent estimates of the precession rate based on historical RPX times (Nicholson et al., 1999 AAS/Division for Planetary Sciences Meeting Abstracts #31 31, 44.01) and from theoretical expectations that account for Titan's 700-yr precession period (Vienne and Duriez 1992, Astronomy and Astrophysics 257, 331-352). The fitted precession rate based on Cassini data only is somewhat lower, which may be an indication of unmodeled shorter term contributions to Saturn's polar motion from other satellites, or perhaps the result of inconsistencies in the assumed

  4. The Galileo Probe: How it Has Changed Our Understanding of Jupiter

    Science.gov (United States)

    Young, Richard E.

    2003-01-01

    The Galileo Mission to Jupiter, which arrived in December of 1995, provided the first study by an orbiter, and the first in-situ sampling via an entry probe, of an outer planet atmosphere. The rationale for an entry probe is that, even from an orbiter, remote sensing of the jovian atmosphere could not adequately retrieve the information desired. This paper provides a current summary of the most significant aspects of the data returned from the Galileo entry probe. As a result of the probe measurements, there has been a reassessment of our understanding of outer planet formation and evolution of the solar system. The primary scientific objective of the Galileo probe was to determine the composition of the jovian atmosphere, which from remote sensing remained either very uncertain, or completely unknown, with respect to several key elements. The probe found that the global He mass fraction is. significantly above the value reported from the Voyager Jupiter flybys but is slightly below the protosolar value, implying that there has been some settling of He to the deep jovian interior. The probe He measurements have also led to a reevaluation of the Voyager He mass fraction for Saturn, which is now determined to be much closer to that of Jupiter. The elements C, N, S, Ar, Kr, Xe were all found to have global abundances approximately 3 times their respective solar abundances. This result has raised a number of fundamental issues with regard to properties of planetesimals and the solar nebula at the time of giant planet formation. Ne, on the other hand, was found to be highly depleted, probably as the result of it being carried along with helium as helium settles towards the deep interior. The global abundance of O was not obtained by the probe because of the influence of local processes at the probe entry site (PES), processes which depleted condensible species, in this case H2O, well below condensation levels. Other condensible species, namely NH3 and H2S, were

  5. VOYAGER 1 SATURN PLASMA DERIVED ION FITS 96 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — THIS DATA SET CONTAINS THE ION PARAMETERS IN THE PLS VOLTAGE RANGE (10-5950 EV/Q) WITH FORMAL 1 SIGMA ERRORS OBTAINED FROM VOYAGER 1 DATA AT SATURN BY FITTING THE...

  6. VOYAGER 1 SATURN PLASMA DERIVED ION FITS BROWSE 96 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — THIS DATA SET CONTAINS THE ION DENSITIES, TEMPERATURES, AND VELOCITIES OBTAINED FROM VOYAGER 1 PLS DATA (VOLTAGE RANGE 10-5950 EV/Q) AT SATURN BY FITTING THE...

  7. VOYAGER 2 SATURN PLASMA DERIVED ELECTRON BROWSE 96 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — THIS DATA SET CONTAINS THE THERMAL ELECTRON DENSITY AND TEMPERATURE IN THE PLS ENERGY RANGE (10-5950 EV) FROM VOYAGER 2 AT SATURN DERIVED BY FITTING THE LOW ENERGY...

  8. VOYAGER 1 SATURN PLASMA DERIVED ELECTRON BROWSE 96 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — THIS DATA SET CONTAINS THE THERMAL ELECTRON DENSITY AND TEMPERATURE IN THE PLS ENERGY RANGE (10-5950 EV) FROM VOYAGER 1 AT SATURN DERIVED BY FITTING THE LOW ENERGY...

  9. Ring-Ringlet Interactions in Saturn's C Ring

    Science.gov (United States)

    Rappaport, N. J.

    1997-01-01

    The overall obejective of this work is to derive a theoretical model for the formation of gaps harboring isolated ringlets in order to explain the presence of such features in Saturn's C ring and Cassini division.

  10. VOYAGER 2 SATURN MAGNETOMETER RESAMPLED DATA 48.0 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 2 Saturn encounter magnetometer data that have been resampled at a 48.0 second sample rate. The data set is composed of 6 columns: 1)...

  11. VOYAGER 1 SATURN MAGNETOMETER RESAMPLED DATA 1.92 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 1 Saturn encounter magnetometer data that have been resampled at a 1.92 second sample rate. The data set is composed of 6 columns: 1)...

  12. VOYAGER 2 SATURN MAGNETOMETER RESAMPLED DATA 9.60 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 2 Saturn encounter magnetometer data that have been resampled at a 9.6 second sample rate. The data set is composed of 6 columns: 1)...

  13. VOYAGER 1 SATURN MAGNETOMETER RESAMPLED DATA 48.0 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 1 Saturn encounter magnetometer data that have been resampled at a 48.0 second sample rate. The data set is composed of 6 columns: 1)...

  14. VOYAGER 2 SATURN MAGNETOMETER RESAMPLED DATA 1.92 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 2 Saturn encounter magnetometer data that have been resampled at a 1.92 second sample rate. The data set is composed of 6 columns: 1)...

  15. VOYAGER 1 SATURN POSITION RESAMPLED DATA 48.0 SECONDS

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 1 Saturn encounter position data that have been generated at a 48.0 second sample rate using the NAIF SPICE kernals. The data set is...

  16. VOYAGER 2 SATURN POSITION RESAMPLED DATA 48.0 SECONDS

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 2 Saturn encounter position data that have been generated at a 48.0 second sample rate using the NAIF SPICE kernals. The data set is...

  17. VOYAGER 1 SATURN MAGNETOMETER RESAMPLED DATA 9.60 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes Voyager 1 Saturn encounter magnetometer data that have been resampled at a 9.6 second sample rate. The data set is composed of 6 columns: 1)...

  18. VOYAGER 2 SATURN PLASMA DERIVED ION FITS 96 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — THIS DATA SET CONTAINS THE ION PARAMETERS IN THE PLS VOLTAGE RANGE (10-5950 EV/Q) WITH FORMAL 1 SIGMA ERRORS OBTAINED FROM VOYAGER 2 DATA AT SATURN BY FITTING THE...

  19. Cassini discovers a kinematic spiral ring around Saturn.

    Science.gov (United States)

    Charnoz, S; Porco, C C; Déau, E; Brahic, A; Spitale, J N; Bacques, G; Baillie, K

    2005-11-25

    Since the time of the Voyager flybys of Saturn in 1980-1981, Saturn's eccentric F ring has been known to be accompanied on either side by faint strands of material. New Cassini observations show that these strands, initially interpreted as concentric ring segments, are in fact connected and form a single one-arm trailing spiral winding at least three times around Saturn. The spiral rotates around Saturn with the orbital motion of its constituent particles. This structure is likely the result of differential orbital motion stretching an initial cloud of particles scattered from the dense core of the F ring. Different scenarios of formation, implying ringlet-satellite interactions, are explored. A recently discovered moon candidate, S/2004 S6, is on an orbit that crosses the F-ring core at the intersection of the spiral with the ring, which suggests a dynamical connection between S/2004 S6 and the spiral.

  20. VOYAGER 1 SATURN PLASMA DERIVED ION MOMENTS 96 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — THIS DATA SET CONTAINS ESTIMATES OF THE ION MOMENT DENSITY IN THE PLS VOLTAGE RANGE (10-5950 EV/Q) AT SATURN DURING THE VOYAGER 1 ENCOUNTER. RIGID COROTATION IS...

  1. VOYAGER 2 SATURN PLASMA DERIVED ION MOMENTS 96 SEC

    Data.gov (United States)

    National Aeronautics and Space Administration — THIS DATA SET CONTAINS ESTIMATES OF THE ION MOMENT DENSITY IN THE PLS VOLTAGE RANGE (10-5950 EV/Q) AT SATURN DURING THE VOYAGER 2 ENCOUNTER. RIGID COROTATION IS...

  2. Lobbying on entry

    NARCIS (Netherlands)

    Perotti, E.C.; Volpin, P.

    2004-01-01

    We develop a model of endogenous lobby formation in which wealth inequality and political accountability undermine entry and financial development. Incumbents seek a low level of effective investor protection to prevent potential entrants from raising capital. They succeed because they can promise

  3. Data Entry Curriculum.

    Science.gov (United States)

    Chinatown Manpower Project, Inc., New York, NY.

    This document describes a project that provides full-time training in the microcomputing area of data entry/word processing as well as job-specific English as a second language (ESL) to adults whose first language is Chinese. The project includes a component that develops the trainees' language proficiency in business communications while…

  4. Deployable Entry-system Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Deployable Entry-system ProjecT (ADEPT) will develop requirements for the ADEPT flight test.  Prior entry systems used high mass thermal protection...

  5. Entry Decision and Pricing Policies

    OpenAIRE

    Sílvia Jorge; Cesaltina Pires

    2007-01-01

    We extend the analysis of the impact of firms' pricing policies upon entry to a framework where price competition and differentiated products are present. We consider a model where an incumbent serves two distinct and independent geographical markets and an entrant may enter in one of the markets. Entry under discriminatory pricing is more likely than under uniform pricing when entry is profitable under discriminatory pricing but unprofitable under uniform pricing. Our results show entry unde...

  6. Irregular Wavelike Structure in Saturn's Rings

    Science.gov (United States)

    Pollard, Benjamin J.

    2005-01-01

    We have searched Saturn's A, B, and C rings for irregular wavelike structure using Voyager Photopolarimeter (PPS), Ultraviolet Spectrometer (UVS), and Radio Science (RSS) occultation datasets, as well as ring reflectivity profiles derived from Voyager images. A maximum entropy technique for conducting spectral analysis was used to estimate wave frequency power in relation to radial location for each dataset. Using this method we have found irregular structure in the PPS and UVS inner B Ring occultation datasets previously identified in Voyager imaging data. Both finer structure, with a wavelength of around 20 km, and large structure with wavelengths of 200 to 1000 km, are visible in the occultation data and appear similar to that seen in the imaging data. After removing ringlets from the C-Ring data, we have identified what appears to be a 1000-km wave sustained throughout the ring. The large dominant wavelength appears in all datasets; however, tests are currently being conducted in an attempt to verify its existence. Irregular structure with a wavelength of approximately 20 km has been observed in the C Ring reflectivity profiles, but not within the occultation datasets. This leads us to doubt it is caused by ring surface mass density fluctuations detectable by the occultation experiments.

  7. Unraveling the strands of Saturn's F ring

    Science.gov (United States)

    Murray, C.D.; Gordon, M.K.; Giuliatti, Winter S.M.

    1997-01-01

    Several high-resolution Voyager 2 images of Saturn's F ring show that it is composed of at least four separate, non-intersecting strands extending ~45?? in longitude. Voyager 1 images show that the two brightest strands appear to intersect, giving rise to a "braided" morphology. From a study of all available Voyager images the detectable radial structure is cataloged and reviewed. Previous indications that there is fine material interior to the orbit of the F ring are confirmed. Evidence is presented that a model of four strands with comparable eccentricities and nearly aligned perichrones is consistent with all the Voyager observations. The observed perichrone offset of the two brightest strands suggests a minimum radial separation of ~20 km, which implies intersection of these strands when their finite radial widths are taken into account. The longitude range of such an intersection includes that observed in the Voyager 1 "braid" images. The proximity of these two strands at some longitudes may account for the apparent differences in the ring between the Voyager encounters, as well as provide a source for the short-lived features detected in the Hubble Space Telescope images of the F ring. There is no evidence that the locations of the individual strands are determined by resonant perturbations with known satellites. It is proposed that the radial structure is formed by the localized action of small satellites orbiting within the strand region. ?? 1997 Academic Press.

  8. Cassini plasma observations of Saturn's magnetospheric cusp

    Science.gov (United States)

    Jasinski, Jamie M.; Arridge, Christopher S.; Coates, Andrew J.; Jones, Geraint H.; Sergis, Nick; Thomsen, Michelle F.; Reisenfeld, Daniel B.; Krupp, Norbert; Waite, J. Hunter

    2016-12-01

    The magnetospheric cusp is a funnel-shaped region where shocked solar wind plasma is able to enter the high-latitude magnetosphere via the process of magnetic reconnection. The plasma observations include various cusp signatures such as ion energy dispersions and diamagnetic effects. We present an overview analysis of cusp plasma observations at the Saturnian magnetosphere from the Cassini spacecraft era. A comparison of the observations is made as well as classification into groups due to varying characteristics. The locations of the reconnection site are calculated and shown to vary along the subsolar magnetopause. We show the first in situ evidence for lobe reconnection that occurred at nearly the same time as dayside reconnection for one of the cusp crossings. Evidence for "bursty" and more "continuous" reconnection signatures is observed at different cusp events. The events are compared to solar wind propagation models, and it is shown that magnetic reconnection and plasma injection into the cusp can occur for a variety of upstream conditions. These are important results because they show that Saturn's magnetospheric interaction with the solar wind and the resulting cusp signatures are dynamic and that plasma injection in the cusp occurs due to a variety of solar wind conditions. Furthermore, reconnection can proceed at a variety of locations along the magnetopause.

  9. Voyager 2 Movie of Saturn's Moon: Phoebe

    Science.gov (United States)

    2000-01-01

    Voyager 2 took this photo sequence of Saturn's outer satellite, Phoebe, on Sept. 4, 1981, from 2.2 million kilometers (1.36 million miles) away. The top image is the normal version and the bottom is an enhanced version to increase resolution. This sequence lasts 23.4 hours and contains 35 images. The early images were taken about 43 minutes apart, while the later ones are about 29 minutes apart. There are two significant gaps in the sequence: images 7 and 8 are separated by 2.3 hours and images 19 and 20 are separated by 2.8 hours.Because the sunlight is coming from the left, mountains and ridges can best be seen as they reflect the sunlight near the terminator (right side of Phoebe). Other intrinsically bright spots can be seen rotating across the whole disk. In this time-lapse sequence, Phoebe appears to be a lumpy spheroid with possible large mountains sometimes showing on the limb (left side of Phoebe). The photos show that Phoebe is about 220 kilometers (132 miles) in diameter. Its rotation period (length of day) was determined from this set of images to be 9.4 hours (see Thomas, P., et al, 'Phoebe: Voyager 2 Observations', Journal of Geophysical Research, vol. 88, p. 8736, 1 November 1983).These images were processed by the Multimission Image Processing Laboratory of the Jet Propulsion Laboratory. The Voyager Project is managed for NASA by the Jet Propulsion Laboratory.

  10. [Biochemical principles of early saturnism recognition].

    Science.gov (United States)

    Tsimakuridze, M P; Mansuradze, E A; Zurashvili, D G; Tsimakuridze, M P

    2009-03-01

    The aim of the work is to determine the major sensitive criteria of biochemical indicators that allow timely discovery of negative influence of lead on organism and assist in early diagnosis of primary stages of saturnism. The workers of Georgian typographies, performing technological processes of letterpress printing were observed. Professional groups having contact with lead aerosols (main group of 66 people) and the workers of the same typography not being in touch with the poison (control group of 24 people) were studied. It was distinguished that, protracted professional contact with lead causes moderate increase of lead, coproporphyrin and DALA in daily urine in most cases; it is more clearly evidenced in the professional groups of lead smelters and lino operators and less clearly among typesetter and printers. Upon the checkup of people, having a direct contact with lead, biochemical analysis of urine should be given a preference, especially the determination of quantitative content of lead and coproporphyrin in urine with the aim of revealing the lead carrier, which is one of the first signals for occupational lookout and medical monitoring of the similar contingent.

  11. The Evolution of Hydrocarbons in Saturn's Northern Storm Region

    Science.gov (United States)

    Bjoraker, Gordon; Hesman, B. E.; Achterberg, R. K.; Romani, P. N.

    2012-01-01

    The massive storm at 40N on Saturn that began in December 2010 has produced significant and lasting effects in the northern hemisphere on temperature and species abundances (Fletcher et aL 2011). The northern storm region was observed on several occasions between March 2011 and April 2012 by Cassini's Composite Infrared Spectrometer (CIRS) at a spectral resolution (0.5/cm) which permits the study of trace species in Saturn's stratosphere. During this time period, stratospheric temperatures in regions referred to as "beacons" (warm regions at specific longitudes at the latitude of the storm) became significantly warmer than pre-storm values of 140K, peaking near 220K, and subsequently cooling. These warm temperatures led to greatly enhanced infrared emission due to C4H2, C3H4, C2H2, and C2H6 in the stratosphere as well as the first detection of C2H4 on Saturn in the thermal infrared (Hesman et al. 2012). Using CH4 as a thermometer of Saturn's stratosphere in the beacon regions, we can derive the mixing ratios of each of these molecules. The most common hydrocarbons (C2H2 and C2H6) serve as dynamical tracers on Saturn and their abundances may constrain vertical motion in the stratosphere. All of these hydrocarbons are products of methane photolysis. Since many of the photochemical reactions that produce heavier hydrocarbons such as C4H2 and C3H4 are temperature sensitive, the beacon region provides a natural laboratory for studying these reactions on Saturn. We will discuss the time evolution of the abundances of each of these hydrocarbons from their pre-storm values, through the period of maximum heating , and during the period of cooling that is taking place in Saturn's stratosphere.

  12. Cultural probes

    DEFF Research Database (Denmark)

    Madsen, Jacob Østergaard

    The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation.......The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation....

  13. Heatshield for Extreme Entry Environment Technology (HEEET) Development Status

    Science.gov (United States)

    Ellerby, Don; Gage, Peter; Kazemba, Cole; Mahzari, Milad; Nishioka, Owen; Peterson, Keith; Stackpoole, Mairead; Venkatapathy, Ethiraj; Young, Zion; Poteet, Carl; hide

    2016-01-01

    The Heat shield for Extreme Entry Environment Technology (HEEET) Project is a NASA STMD and SMD co-funded effort. The goal is to develop and mission infuse a new ablative Thermal Protection System that can withstand extreme entry. It is targeted to support NASAs high priority missions, as defined in the latest decadal survey, to destinations such as Venus and Saturn in-situ robotic science missions. Entry into these planetary atmospheres results in extreme heating. The entry peak heat-flux and associated pressure are estimated to be between one and two orders of magnitude higher than those experienced by Mars Science Laboratory or Lunar return missions. In the recent New Frontiers community announcement NASA has indicated that it is considering providing an increase to the PI managed mission cost (PIMMC) for investigations utilizing the Heat Shield for Extreme Entry Environment Technology (HEEET) and in addition, NASA is considering limiting the risk assessment to only their accommodation on the spacecraft and the mission environment. The HEEET ablative TPS utilizes 3D weaving technology to manufacture a dual layer material architecture. The 3-D weaving allows for flat panels to be woven. The dual layer consists of a top layer designed to withstand the extreme external environment while the inner or insulating layer by design, is designed to achieve low thermal conductivity, and it keeps the heat from conducting towards the structure underneath. Both arc jet testing combined with material properties have been used to develop thermal response models that allows for comparison of performance with heritage carbon phenolic. A 50 mass efficiency is achieved by the dual layer construct compared to carbon phenolic for a broad range of missions both to Saturn and Venus. The 3-D woven flat preforms are molded to achieve the shape as they are compliant and then resin infusion with curing forms a rigid panels. These panels are then bonded on to the aeroshell structure. Gaps

  14. On the dynamical nature of Saturn's North Polar hexagon

    Science.gov (United States)

    Rostami, Masoud; Zeitlin, Vladimir; Spiga, Aymeric

    2017-11-01

    An explanation of long-lived Saturn's North Polar hexagonal circumpolar jet in terms of instability of the coupled system polar vortex - circumpolar jet is proposed in the framework of the rotating shallow water model, where scarcely known vertical structure of the Saturn's atmosphere is averaged out. The absence of a hexagonal structure at Saturn's South Pole is explained similarly. By using the latest state-of-the-art observed winds in Saturn's polar regions a detailed linear stability analysis of the circumpolar jet is performed (i) excluding (;jet-only; configuration), and (2) including (;jet + vortex; configuration) the north polar vortex in the system. A domain of parameters: latitude of the circumpolar jet and curvature of its azimuthal velocity profile, where the most unstable mode of the system has azimuthal wavenumber 6, is identified. Fully nonlinear simulations are then performed, initialized either with the most unstable mode of small amplitude, or with the random combination of unstable modes. It is shown that developing barotropic instability of the ;jet+vortex; system produces a long-living structure akin to the observed hexagon, which is not the case of the ;jet-only; system, which was studied in this context in a number of papers in literature. The north polar vortex, thus, plays a decisive dynamical role. The influence of moist convection, which was recently suggested to be at the origin of Saturn's North Polar vortex system in the literature, is investigated in the framework of the model and does not alter the conclusions.

  15. Saturn's aurora in the January 2004 events

    Directory of Open Access Journals (Sweden)

    E. S. Belenkaya

    2006-07-01

    Full Text Available Differences in the solar wind interaction with the magnetosphere of Saturn relative to the Earth result from the decrease in the solar wind plasma density and magnetic field strength with distance from the Sun, and from the change in the average angle of the IMF at Saturn's orbit. Other reasons are related to Saturn's rapid rotation and internal magnetospheric plasma sources. Moreover, the IMF structure observed by Cassini in 2003–2004 during the approach to Saturn is consistent with corotating interaction regions (CIRs existing during the declining phase of the solar cycle. Two cases on 16 and 26 January 2004 are considered when disturbances in the solar wind passed Cassini and then Saturn. After the solar wind shock encountered the kronian magnetosphere, the auroral oval became brighter (especially at dawn with a reduced radius. In these cases the auroral power was anti-correlated with the radius of the oval. Possible mechanisms responsible for such unexpected behavior are presented and discussed in detail.

  16. Extracting the Radial Profile of Saturn's Phoebe Ring

    Science.gov (United States)

    Tamayo, Daniel; Markham, Stephen R.; Hedman, Matthew M.; Burns, Joseph A.

    2014-11-01

    Saturn is famous for its dramatic main rings. Less well known is that two orders of magnitude further away from the planet, Saturn also hosts the solar system’s largest known circumplanetary ring. This Phoebe ring is likely sourced by collisions with Saturn’s largest irregular satellite Phoebe, and presents an important opportunity to learn more generally about the collisional evolution of this distant population of irregular satellites. Debris from such collisions is likely ultimately responsible for the dramatic two-faced coloration of the odd moon Iapetus.We present results from recent observations with the Cassini spacecraft (in orbit about Saturn) in scattered optical light. Using a novel observational technique that exploits the moving shadow cast by Saturn, we have been able to clearly extract the exceedingly faint Phoebe ring signal (line-of-sight optical depth ˜ 10e-9, surface brightness ˜ 27 mag/arcsec^2). Additionally, we present reconstructed radial profiles over the broad range of distances from Saturn spanned by our observations.

  17. The Atmospheric Dynamics of Jupiter, Saturn, and Titan

    Science.gov (United States)

    Flasar, F. M.

    2009-01-01

    Comparative studies of Jupiter and Saturn often emphasize their similarities, but recent observations have highlighted important differences. The stratospheres of both planets exhibit an equatorial oscillation reminiscent of that in Earth's middle atmosphere. Jupiter's oscillation has a 4-5 year period, not linked to its season, and it has been modeled as an analog to the terrestrial quasi-biennial oscillation, driven by the stresses associated with vertically propagating waves. Saturn's equatorial oscillation is nearly semiannual, but wave activity may still be a driver. Jupiter's internal rotation rate is inferred from its steady modulated radio emission. Saturn's internal rotation is more enigmatic. It has been inferred from the modulation of the body's kilometric radio emission, but this period has varied by 1% over the last 25 years. Saturn's equatorial winds are also puzzling, as those inferred from cloud tracking by Cassini and more recent HST observations are weaker than those from Voyager. Whether this is attributable to a difference in altitudes of the tracked clouds in winds with vertical shear or a real temporal change in the winds is not known. Both winter and summer poles of Saturn exhibit very compact circumpolar vortices with warm cores, indicating subsidence. Titan's middle atmosphere is characterized by global cyclostrophic winds, particularly the strong circumpolar vortex in the winter hemisphere. In many ways, the spatial distribution of temperature, gaseous constituents, and condensates is reminiscent of conditions in terrestrial winter vortices, albeit with different chemistry. The meridional contrast in Titan's tropospheric temperatures is small, only a few kelvins.

  18. Exploration of the Saturn System by the Cassini Mission: Observations with the Cassini Infrared Spectrometer

    Science.gov (United States)

    Abbas, Mian M.

    2014-01-01

    Outline: Introduction to the Cassini mission, and Cassini mission Objectives; Cassini spacecraft, instruments, launch, and orbit insertion; Saturn, Rings, and Satellite, Titan; Composite Infrared Spectrometer (CIRS); and Infrared observations of Saturn and titan.

  19. Saturn's rings thickness with the shadow hiding

    Science.gov (United States)

    Deau, Estelle; Brahic, André; Porco, Carolyn

    Using the Hapke shadow hiding model on various curves phases of ISS/Cassini, we were able to compute the thickness of Saturn's rings through the photometric filling factor. Our results show that diffuse rings (C ring and Cassini Division) are distributed in a monolayer with a thickness from a few centimeters to 5 meters. This seems to suggest that the layer is smaller than the larger particles. For the A and B rings, we find a thickness ranging from 10 to 20 meters, then leading to multiple layers of particles. Our results for the A ring are systematically lower than the values derived by density waves (Tiscareno et al., 2007) and dynamical simulations of Salo and Kaarjalainen (2003). For the first one, this can be explain by the fact the vertical height of the density waves are the upper limit of the real height. Indeed, the wakes (Julian & Toomre, 1966; Salo 1995) conduce the viscosity in the A ring (Daisaka et al., 2001), and produce random speeds greater in the ring plane than in the vertical direction (Daisaka & Ida, 1999), thereby reducing the thickness given by the vertical random speed used to compute the vertical height. However, for the latter one, simulations lead in all the cases (A and B rings such as C ring and Cassini Division) to vertical height of few meters. This constancy can be explained by the fact that simulations take a size distribution too truncated, and a coefficient of restitution rather simple (indeed, rings reflect different surface conditions related to the optical depth, thus the Bridges' law could not promote only one type of collisions). Finally, our results prefer monolayer (layer smaller than the larger particles which allow multilayer of smaller particules) for the faint rings (C ring and Cassini Division) and multilayer for the A and B rings.

  20. Hydrocarbons on Saturn's satellites Iapetus and Phoebe

    Science.gov (United States)

    Cruikshank, D.P.; Wegryn, E.; Dalle, Ore C.M.; Brown, R.H.; Bibring, J.-P.; Buratti, B.J.; Clark, R.N.; McCord, T.B.; Nicholson, P.D.; Pendleton, Y.J.; Owen, T.C.; Filacchione, G.; Coradini, A.; Cerroni, P.; Capaccioni, F.; Jaumann, R.; Nelson, R.M.; Baines, K.H.; Sotin, Christophe; Bellucci, G.; Combes, M.; Langevin, Y.; Sicardy, B.; Matson, D.L.; Formisano, V.; Drossart, P.; Mennella, V.

    2008-01-01

    Material of low geometric albedo (pV ??? 0.1) is found on many objects in the outer Solar System, but its distribution in the saturnian satellite system is of special interest because of its juxtaposition with high-albedo ice. In the absence of clear, diagnostic spectral features, the composition of this low-albedo (or "dark") material is generally inferred to be carbon-rich, but the form(s) of the carbon is unknown. Near-infrared spectra of the low-albedo hemisphere of Saturn's satellite Iapetus were obtained with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft at the fly-by of that satellite of 31 December 2004, yielding a maximum spatial resolution on the satellite's surface of ???65 km. The spectral region 3-3.6 ??m reveals a broad absorption band, centered at 3.29 ??m, and concentrated in a region comprising about 15% of the low-albedo surface area. This is identified as the C{single bond}H stretching mode vibration in polycyclic aromatic hydrocarbon (PAH) molecules. Two weaker bands attributed to {single bond}CH2{single bond} stretching modes in aliphatic hydrocarbons are found in association with the aromatic band. The bands most likely arise from aromatic and aliphatic units in complex macromolecular carbonaceous material with a kerogen- or coal-like structure, similar to that in carbonaceous meteorites. VIMS spectra of Phoebe, encountered by Cassini on 11 June 2004, also show the aromatic hydrocarbon band, although somewhat weaker than on Iapetus. The origin of the PAH molecular material on these two satellites is unknown, but PAHs are found in carbonaceous meteorites, cometary dust particles, circumstellar dust, and interstellar dust. ?? 2007 Elsevier Inc. All rights reserved.

  1. The Voyager encounters with Saturn (Dryden Lectureship in Research)

    Science.gov (United States)

    Stone, E. C.

    1983-01-01

    In 1972, the Voyager Program was undertaken by NASA as a major step in the exploration of the outer solar system. Recently the objectives of this program have been extended to include an investigation of Uranus and possibly Neptune. In connection with the present investigation, a brief description of the Voyager spacecraft is presented and an overview of the scientific results from the Saturn encounters is provided. Two essentially identical Voyager spacecraft were launched in 1977 toward encounters with the Jovian and Saturnian planetary systems. The Voyager 1 trajectory at Saturn was chosen to provide a close encounter with Titan, a planet-sized satellite with an atmosphere, and to provide an optimum geometry for dual-frequency radio occultation studies of Saturn's rings. The Voyager 2 trajectory provided improved viewing of the rings.

  2. How Cassini can constrain tidal dissipation in Saturn

    Science.gov (United States)

    Luan, Jing; Fuller, Jim; Quataert, Eliot

    2018-02-01

    Tidal dissipation inside giant planets is important for the orbital evolution of their natural satellites. It is conventionally treated by parametrized equilibrium tidal theory, in which the tidal torque declines rapidly with distance, and orbital expansion was faster in the past. However, some Saturnian satellites are currently migrating outward faster than predicted by equilibrium tidal theory. Resonance locking between satellites and internal oscillations of Saturn naturally matches the observed migration rates. Here, we show that the resonance locking theory predicts dynamical tidal perturbations to Saturn's gravitational field in addition to those produced by equilibrium tidal bulges. We show that these perturbations can likely be detected during Cassini's proximal orbits if migration of satellites results from resonant gravity modes, but will likely be undetectable if migration results from inertial wave attractors or dissipation of the equilibrium tide. Additionally, we show that the detection of gravity modes would place constraints on the size of the hypothetical stably stratified region in Saturn.

  3. Particle Sizes and Self Gravity Wakes in Saturn's A Ring

    Science.gov (United States)

    Jerousek, R. G.; Colwell, J. E.; Esposito, L. W.; Nicholson, P. D.

    2015-12-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) and Visual and Infrared Mapping Spectrometer (VIMS) have measured normal optical depths throughout Saturn's rings by stellar occultations covering a wide range of viewing geometries. The UVIS photometer has an effective wavelength of 0.15 µm and a relatively wide (6.0 mrad × 6.4 mrad) field-of-view. VIMS, in occultation mode, measures at an effective wavelength of 2.9 µm and over a single pixel of angular dimensions 0.25 mrad × 0.5 mrad. Occultations measured by VIMS at the same viewing geometry as UVIS occultations overstate the optical depth if particles smaller than 1.22λVIMS/2θ ~ 8.36 mm are present because light diffracted out of the VIMS pixel by those particles is not replaced by neighboring particles. By measuring differential optical depths one can probe the parameters of the ring particle size distribution (i.e. Zebker et al. 1985, Icarus, 64, 531-548). The technique is complicated, however, by the geometric dependence of the optical depth imposed by the non-axisymmetric self-gravity wakes, which are ephemeral elongated aggregates, deformed by Keplerian shear. Beginning with the granola bar wake model of Colwell et al. (2006, Geophys. Res. Lett., 33, L07201), we introduce a free parameter τsmall which represents the excess normal optical depth measured by VIMS due to sub-cm particles between the opaque wakes and combine VIMS and UVIS occultations for particle size analysis while simultaneously determining the properties of the wakes. We find that throughout the A Ring the wake properties generally agree with previously published results (Colwell et al. 2006, Hedman et al. 2007, Astron. J., 133, 2624-2629). We find a significant fraction of sub-cm particles in the inner and outer A Ring and in the troughs of density waves near strong Lindblad resonances. While wake properties vary in the halo regions surrounding these resonances, the abundance of sub-cm particles varies little from 124

  4. Saturn's Rings II. Particle Sizes Inferred from Stellar Occultation Data

    Science.gov (United States)

    French, Richard G.; Nicholson, Philip D.

    2000-06-01

    We derive power-law particle size distributions for each of Saturn's main ring regions, using observations of the 3 July 1989 stellar occultation of 28 Sgr from Palomar, McDonald, and Lick observatories. We use the Voyager PPS δ Sco optical depth profile to estimate and then remove the directly transmitted signal from the 28 Sgr observations, leaving high SNR scattered light profiles at wavelengths of 3.9, 2.1, and 0.9 μm. The angular distribution of this diffracted signal depends on the ring particle size distribution: the sharpness of the forward lobe is set by the largest particles, while the overall breadth and amplitude of the scattered signal reflect the abundance of smaller, cm-sized particles. From a simple one-dimensional scattering model, we estimate characteristic particle sizes in the A, B, and C rings, and obtain a good match to the detailed structure of the observed scattered light profiles. To accommodate more realistic particle size distributions and to take proper account of the geometry of the occultation, we then develop a two-dimensional forward-scattering model. We assume for simplicity a single power law particle size distribution for each major ring region, and we determine the index q and lower and upper size cutoffs amin and amax that provide the best match to all three data sets in each region. Our results in the A and C rings are fairly consistent with values of q and amax derived from Voyager radio occultation (RSS) measurements (Zebker et al. 1985). We extend their results by determining lower limits to the particle size distributions and by probing the B Ring. We find a rather flat ( q=2.75) and narrow size distribution for both the inner A Ring and the B Ring, with a surprisingly large amin=30 cm. From the detailed shape of the scattered signal in the A and B rings, we find amax=20 m, a factor of two larger than the RSS result. The fraction of cm-sized particles increases between the inner and outer A Ring and is greatest in the C

  5. A conceptual Saturn ring observer mission using standard radioisotope power systems

    Science.gov (United States)

    Abelson, Robert D.; Spilker, Thomas R.

    2006-01-01

    Saturn remains of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields.

  6. Saturn's Internal Structure: A View through its Natural Seismograph

    Science.gov (United States)

    Mankovich, Christopher; Marley, Mark S.; Fortney, Jonathan J.; Movshovitz, Naor

    2017-10-01

    Saturn's nonradial oscillations perturb the orbits of ring particles. The C ring is fortuitous in that it spans several resonances with Saturn's fundamental acoustic (f-) modes, and its moderate optical depth allows the characterization of wave features using stellar occultations. The growing set of C-ring waves with precise pattern frequencies and azimuthal order m measured from Cassini stellar occultations (Hedman & Nicholson 2013, 2014; French et al. 2016) provides new constraints on Saturn's internal structure, with the potential to resolve long-standing questions about the planet's distribution of helium and heavier elements, its means of internal energy transport, and its rotation state.We construct Saturn interior models and calculate mode eigenfrequencies, mapping the planet mode frequencies to resonant locations in the rings to compare with the locations of observed spiral density and vertical bending waves in the C ring. While spiral density waves at low azimuthal order (m=2-3) appear strongly affected by resonant coupling between f-modes and deep g-modes (Fuller 2014), the locations of waves with higher azimuthal order can be fit reasonably well with a spectrum of pure f-modes for Saturn models with adiabatic envelopes and realistic equations of state. In particular, four observed bending waves (Nicholson et al., DPS 2016) align with outer vertical resonances for non-sectoral (m≠l) Saturn f-modes of relatively high angular degree, and we present preliminary identifications of these. We assess the range of resonance locations in the C and D rings allowed for the spectrum of f-modes given gravity field constraints and discuss what role a realistic helium distribution in the planet might play.

  7. Evolution of Saturn's mid-sized icy moons

    Science.gov (United States)

    Neveu, M.; Rhoden, A. R.

    2017-09-01

    We aim to reproduce the orbits (semi-major axes and eccentricities), and interiors (core radii, oceans) of the mid-sized moons of Saturn (Mimas, Enceladus, Tethys, Dione, and Rhea) as constrained by data from the Cassini spacecraft. We numerically model the coupled geophysical and orbital evolution of all moons, assuming they formed late from Saturn's rings. Our results closely reproduce observations, but only if Enceladus is initially warmer than what heating from impacts during its formation would provide. Notably, our models reconcile the moons' dynamical youth and geological diversity. We discuss next steps in improving the fidelity of our models.

  8. Paralympic Games sport entries mamual

    OpenAIRE

    2014-01-01

    This manual is designed to provide National Paralympic Committees (NPCs) with the Paralympic Sport Entries process, relevant policies, and instructions for completing the online registration for athletes participating in the Sochi 2014 Paralympic Winter Games and to assist NPCs in using the online Sport Entries and Qualification (ePEQ) system to complete the entries of their athletes to the Sochi 2014 Paralympic Winter Games.

  9. What confines the rings of Saturn?

    Science.gov (United States)

    Tajeddine, Radwan; Nicholson, Philip D.; El Moutamid, Maryame; Longaretti, Pierre-Yves; Burns, Joseph A.

    2017-10-01

    The viscous spreading of planetary rings is believed to be counteracted by satellite torques, either through an individual resonance or through overlapping resonances (when the satellite is close to the ring edge). For the A ring of Saturn, it has been commonly believed that the satellite Janus alone can prevent the ring from spreading via its 7:6 Lindblad resonance. We discuss this common misconception and show that, in reality, the A ring is confined by the contributions from the group of satellites Pan, Atlas, Prometheus, Pandora, Janus, Epimetheus, and Mimas, whose resonances gradually decrease the angular momentum flux transported outward through the ring via density and bending waves. We further argue that this decrease in angular momentum flux occurs through the mechanism of ‘flux reversal’.We find that the Janus 7:6 torque is relatively feeble, as is the comparable torque of the nearby small satellite Atlas, each amounting to less than one-tenth of the angular momentum transport carried by the A ring. But the cumulative torques of the many other satellite resonances in the A ring sufficiently reduce the angular momentum flux through the rings so that the torques due to Janus and Atlas are effective in confining the outer edge of the ring.Furthermore, we use the magnitude of the satellites’ resonance torques to estimate the effective viscosity profile across the A ring, showing that it decreases from ~50 cm2 s-1 at the inner edge to less than ~11 cm2 s-1 at the outer edge. The gradual estimated decrease of the angular momentum flux and effective viscosity are roughly consistent with results obtained by balancing the shepherding torques from Pan and Daphnis with the viscous torque at the edges of the Encke and Keeler gaps, as well as the edge of the A ring.On the other hand, the Mimas 2:1 Lindblad resonance alone seems to be capable of confining the edge of the B ring, and contrary to the situation in the A ring, we show that the effective viscosity

  10. Advertising and generic market entry.

    Science.gov (United States)

    Königbauer, Ingrid

    2007-03-01

    The effect of purely persuasive advertising on generic market entry and social welfare is analysed. An incumbent has the possibility to invest in advertising which affects the prescribing physician's perceived relative qualities of the brand-name and the generic version of the drug. Advertising creates product differentiation and can induce generic market entry which is deterred without differentiation due to strong Bertrand competition. However, over-investment in advertising can deter generic market entry under certain conditions and reduces welfare as compared to accommodated market entry.

  11. First Results of ISO-SWS Grating Observations of Saturn

    NARCIS (Netherlands)

    de Graauw, Th.; Encrenaz, Th.; Schaeidt, S.; Lellouch, E.; Feuchtgruber, H.; Beintema, D. A.; Bezard, B.; Drossart, P.; Griffin, M.; Heras, A.; Kessler, M.; Leech, K.; Morris, A.; Roelfsema, P. R.; Roos-Serote, M.; Salama, A.; Vandenbussche, B.; Valentijn, E. A.; Davies, G. R.; Naylor, D. A.

    1996-01-01

    The spectrum of Saturn has been recorded between 2.3 and 15 mu m, on June 13, 1996, with the grating mode of the Short-Wavelength Spectrometer of ISO (Infrared Space Observatory). The resolving power is about 1500 and the sensitivity is better than 1 Jy. As compared to Jupiter, the spectrum of

  12. Cassini at Saturn Proximal Orbits - Attitude Control Challenges

    Science.gov (United States)

    Burk, Thomas A.

    2013-01-01

    The Cassini mission at Saturn will come to an end in the spring and summer of 2017 with a series of 22 orbits that will dip inside the rings of Saturn. These are called proximal orbits and will conclude with spacecraft disposal into the atmosphere of the ringed world on September 15, 2017. These unique orbits that cross the ring plane only a few thousand kilometers above the cloud tops of the planet present new attitude control challenges for the Cassini operations team. Crossing the ring plane so close to the inner edge of the rings means that the Cassini orientation during the crossing will be tailored to protect the sensitive electronics bus of the spacecraft. This orientation will put the sun sensors at some extra risk so this paper discusses how the team prepares for dust hazards. Periapsis is so close to the planet that spacecraft controllability with RCS thrusters needs to be evaluated because of the predicted atmospheric torque near closest approach to Saturn. Radiation during the ring plane crossings will likely trigger single event transients in some attitude control sensors. This paper discusses how the attitude control team deals with radiation hazards. The angular size and unique geometry of the rings and Saturn near periapsis means that star identification will be interrupted and this paper discusses how the safe mode attitude is selected to best deal with these large bright bodies during the proximal orbits.

  13. Survey of Saturn electrostatic cyclotron harmonic wave intensity

    Science.gov (United States)

    Menietti, J. D.; Averkamp, T. F.; Kurth, W. S.; Ye, S.-Y.; Gurnett, D. A.; Cecconi, B.

    2017-08-01

    We conduct a survey of electrostatic electron cyclotron harmonic (ECH) emissions observed at Saturn by the radio and plasma wave science investigation on board the Cassini spacecraft. These emissions are known to be effective at interacting with electrons in the terrestrial inner magnetosphere, producing electron scattering into the loss cone and acceleration (cf. Horne and Thorne, 2000; Thorne et al., 2010). At Saturn ECH emission occurs with high probability and at strong intensity near the magnetic equator, outside the Enceladus torus in the range 5 < L < 10. Inside the inner boundary of the torus, ECH emissions are also observed near the equator and at higher latitude. Intensity levels of ECH emission are comparable to those observed at Earth, higher than Saturn chorus and Z-mode emission, and are likely to scatter electrons into the loss cone as at Earth. ECH waves are particularly intense and extend to higher harmonics within some plasma injection regions. We present results for a survey of over 8 years of Saturn data for fundamental and up to three harmonics of fce, the electron cyclotron frequency.

  14. Conductivity Probe

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  15. INMS measures an influx of molecules from Saturn's rings

    Science.gov (United States)

    Perry, Mark E.; Cassini INMS Team

    2017-10-01

    In 1984, Connerney and Waite proposed water influx from Saturn's rings to explain the low electron densities measured during Pioneer and Voyager radio occultation experiments. Charge exchange with this minor species depleted the H+ ions and provided a faster path to electron recombination. With ice the primary constituent of the rings, water was the most likely in-falling molecule.During the Grand Finale orbits, Cassini's Ion and Neutral Mass Spectrometer (INMS) detected and quantified an influx from the rings. Unexpectedly, the primary influx molecules are CH4 and a heavier carbon-bearing species. Water was detected, but quantities were factors of ten lower than these other species.Distribution in both altitude and latitude are consistent with a ring influx. The concentration of the minor species in Saturn's atmosphere shows that they enter Saturn's atmosphere from the top. Both molecules have their highest concentrations at the highest altitudes, with concentrations >0.4% at 3,500 km altitude and only 0.02% at 2,700 km. Molecules from the rings deorbit to Saturn's atmosphere at altitudes near 4,000 km, consistent with the INMS measurements.The latitudinal dependence of the minor species indicates that their source is near the equatorial plane. At high altitudes, the minor species were observed primarily at zero latitude, where the 28u species was six times more concentrated than at 5° latitude. At lower altitudes, the peaking ratio was 1, indicating that the species had diffused and was fully mixed into Saturn's H2 atmosphere. The lighter molecule, CH4, diffuses more rapidly than the 28u species. INMS also detected both of these species during the earlier F-ring passes, finding that the neutrals were centered at the ring plane and extended 3,000 km (half width, half max) north and south.

  16. Saturn's Ring: Pre-Cassini Status and Mission Goals

    Science.gov (United States)

    Cuzzi, Jeff N.; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    In November 1980, and again in August 1981, identical Voyager spacecraft flew through the Saturn system, changing forever the way we think about planetary rings. Although Saturn's rings had been the only known ring system for three centuries, a ring system around Uranus had been discovered by stellar occultations from Earth in 1977, and the nearly transparent ring of Jupiter was imaged by Voyager in 1979 (the presence of material there had been inferred from charged particle experiments on Pioneer 10 and 11 several years earlier). While Saturn had thus temporarily lost its uniqueness as having the only ring system, with Voyager it handily recaptured the role of having the most fascinating one. The Voyager breakthroughs included spiral density and bending waves such as cause galactic structure; ubiquitous fine-scale radial 'irregular' structure, with the appearance of record-grooves; regional and local variations in particle color; complex, azimuthally variable ring structure; empty gaps in the rings, some containing very regular, sharp-edged, elliptical rings and one containing both a small moonlet and incomplete arcs of dusty material; and shadowy 'spokes' that flicker across the main rings. One of the paradigm shifts of this period was the realization that many aspects of planetary rings, and even the ring systems themselves, could be 'recent' on geological timescales. These early results are reviewed and summarized in the Arizona Space Science series volumes 'Saturn'. (An excellent review of ring dynamics at a formative stage is by Goldreich and Tremaine.) From the mid 1980's to the time of this writing, progress has been steady, while at a less heady pace, and some of the novel ring properties revealed by Voyager 1 and 2 are beginning to be better understood. It is clearly impossible to cite, much less review, every advance over the last decade; however, below we summarize the main advances in understanding of Saturn's rings since the mid 1980's, in the context

  17. Pollution Probe.

    Science.gov (United States)

    Chant, Donald A.

    This book is written as a statement of concern about pollution by members of Pollution Probe, a citizens' anti-pollution group in Canada. Its purpose is to create public awareness and pressure for the eventual solution to pollution problems. The need for effective government policies to control the population explosion, conserve natural resources,…

  18. Mobile probes

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Jørgensen, Anna Neustrup; Noesgaard, Signe Schack

    2016-01-01

    to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...

  19. HIV: cell binding and entry

    National Research Council Canada - National Science Library

    Wilen, Craig B; Tilton, John C; Doms, Robert W

    2012-01-01

    The first step of the human immunodeficiency virus (HIV) replication cycle-binding and entry into the host cell-plays a major role in determining viral tropism and the ability of HIV to degrade the human immune system...

  20. Tactile Data Entry System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Building on our successful Phase I Tactile Data Entry program, Barron Associates proposes development of a Glove-Enabled Computer Operations (GECO) system to permit...

  1. Erratum: Voyager Color Photometry of Saturn's Main Rings

    Science.gov (United States)

    Estrada, Paul R.; Cuzzi, Jeffrey N.; Showalter, Mark R.; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    We correct a calibration error in our earlier analysis of Voyager color observations of Saturn's main rings at 14 deg phase angle and present thoroughly revised and reanalyzed radial profiles of the brightness of the main rings in Voyager G, V, and UV filters, and ratios of these brightnesses. These results are consistent with more recent HST results at 6 deg phase angle, once allowance is made for plausible phase reddening of the rings. Unfortunately, the Voyager camera calibration factors are simply not sufficiently well known for a combination of the Voyager and HST data to be used to constrain the phase reddening quantitatively. However, some interesting radial variations in reddening between 6-14 deg phase angles are hinted at. We update a ring-and-satellite color vs. albedo plot from Cuzzi and Estrada in several ways. The A and B rings are still found to be in a significantly redder part of color-albedo space than Saturn's icy satellites.

  2. Observations of ejecta clouds produced by impacts onto Saturn's rings.

    Science.gov (United States)

    Tiscareno, Matthew S; Mitchell, Colin J; Murray, Carl D; Di Nino, Daiana; Hedman, Matthew M; Schmidt, Jürgen; Burns, Joseph A; Cuzzi, Jeffrey N; Porco, Carolyn C; Beurle, Kevin; Evans, Michael W

    2013-04-26

    We report observations of dusty clouds in Saturn's rings, which we interpret as resulting from impacts onto the rings that occurred between 1 and 50 hours before the clouds were observed. The largest of these clouds was observed twice; its brightness and cant angle evolved in a manner consistent with this hypothesis. Several arguments suggest that these clouds cannot be due to the primary impact of one solid meteoroid onto the rings, but rather are due to the impact of a compact stream of Saturn-orbiting material derived from previous breakup of a meteoroid. The responsible interplanetary meteoroids were initially between 1 centimeter and several meters in size, and their influx rate is consistent with the sparse prior knowledge of smaller meteoroids in the outer solar system.

  3. Photometric changes on Saturn's Titan: Evidence for active cryovolcanism

    Science.gov (United States)

    Nelson, R.M.; Kamp, L.W.; Lopes, R.M.C.; Matson, D.L.; Kirk, R.L.; Hapke, B.W.; Wall, S.D.; Boryta, M.D.; Leader, F.E.; Smythe, W.D.; Mitchell, K.L.; Baines, K.H.; Jaumann, R.; Sotin, Christophe; Clark, R.N.; Cruikshank, D.P.; Drossart, P.; Lunine, J.I.; Combes, M.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Filacchione, G.; Langevin, Y.; McCord, T.B.; Mennella, V.; Nicholson, P.D.; Sicardy, B.; Irwin, P.G.J.; Pearl, J.C.

    2009-01-01

    We report infrared spectrophotometric variability on the surface of Saturn's moon Titan detected in images returned by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini Saturn Orbiter. The changes were observed at 7??S, 138??W and occurred between October 27, 2005 and January 15, 2006. After that date the surface was unchanged until the most recent observation, March 18, 2006. We previously reported spectrophotometric variability at another location (26??S, 78??W). Cassini Synthetic Aperture RADAR (SAR) images find that the surface morphology at both locations is consistent with surface flows possibly resulting from cryovolcanic activity (Wall et al., companion paper, this issue). The VIMS-reported time variability and SAR morphology results suggest that Titan currently exhibits intermittent surface changes consistent with present ongoing surface processes. We suggest that these processes involve material from Titan's interior being extruded or effiised and deposited on the surface, as might be expected from cryovolcanism. ?? 2009.

  4. Impact of saturn ring particles on pioneer 11.

    Science.gov (United States)

    Humes, D H; O'neal, R L; Kinard, W H; Alvarez, J M

    1980-01-25

    The particle flux measured by the meteoroid detectors on Pioneer 11 increased greatly while the spacecraft was near the rings of Saturn. The data suggest that the particles were associated with the rings and were not interplanetary meteoroids concentrated near the planet by gravitational focusing. The data also suggest that the E ring may be 1800 kilometers thick with an optical thickness greater than 10(-8).

  5. MeV proton flux predictions near Saturn's D ring.

    Science.gov (United States)

    Kollmann, P; Roussos, E; Kotova, A; Cooper, J F; Mitchell, D G; Krupp, N; Paranicas, C

    2015-10-01

    Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.

  6. Detection and Behavior of Pan Wakes in Saturn's A Ring

    Science.gov (United States)

    Horn, L. J.; Showalter, M. R.; Russell, C. T.

    1996-01-01

    Six previously unseen Pan wakes are found interior and exterior to the Encke gap in Saturn's A ring, one in the Voyager 2 photopolarimeter (PPS) stellar occultation data and five in the Voyager 1 radio science (RSS) Earth occultation data. Pan orbits at the center of the Encke gap and maintains it...The detection of Pan wakes at longitudes greater than 360(deg) demonstrates that wakes persist for much longer than originally hypothesized and may interact with one another.

  7. Sir John Herschel and the Stability of Saturn's Ring

    CERN Document Server

    Whiting, Alan B

    2011-01-01

    In a pioneering exposition of mathematical astronomy for the public, Sir John Herschel attributed the stability of the ring of Saturn to its being eccentric with respect to the planet and lopsided (asymmetric in mass) by a minute amount. Tracing the sources and effects of this error reveals several lessons of general relevance to science: on the formulation and interpretation of calculations, the use of cutting-edge observations and the combining of observations with theory. I emphasise the phenomenon of reinforcing errors.

  8. Resistive Heating and Ion Drag in Saturn's Thermosphere

    Science.gov (United States)

    Vriesema, Jess William; Koskinen, Tommi; Yelle, Roger V.

    2017-10-01

    One of the most puzzling observations of the jovian planets is that the thermospheres of Jupiter, Saturn, Uranus and Neptune are all several times hotter than solar heating can account for (Strobel and Smith 1973; Yelle and Miller 2004; Muller-Wodarg et al. 2006). On Saturn, resistive heating appears sufficient to explain these temperatures in auroral regions, but the particular mechanism(s) responsible for heating the lower latitudes remains unclear. The most commonly proposed heating mechanisms are breaking gravity waves and auroral heating at the poles followed by redistribution of energy to mid-and low latitudes. Both of these energy sources are potentially important but also come with significant problems. Wave heating would have to be continuous and global to produce consistently elevated temperatures and the strong Coriolis forces coupled with polar ion drag appear to hinder redistribution of auroral energy (see Strobel et al. 2016 for review). Here we explore an alternative: wind-driven electrodynamics that can alter circulation and produce substantial heating outside of the auroral region. Smith (2013) showed this in-situ mechanism to be potentially significant in Jupiter’s thermosphere. We present new results from an axisymmetric, steady-state model that calculates resistive (Joule) heating rates through rigorous solutions of the electrodynamic equations for the coupled neutral atmosphere and ionosphere of Saturn. At present, we assume a dipole magnetic field and neglect any contributions from the magnetosphere. We use ion mixing ratios from the model of Kim et al. (2014) and the observed temperature-pressure profile from Koskinen et al. (2015) to calculate the generalized conductivity tensor as described by Koskinen et al. (2014). We calculate the current density under the assumption that it has no divergence and use it to calculate the resistive heating rates and ion drag. Our results suggest that resistive heating and ion drag at low latitudes likely

  9. Dust Transport from Enceladus to the moons of Saturn

    Science.gov (United States)

    Juhasz, A.; Hsu, H. W.; Kempf, S.; Horanyi, M.

    2016-12-01

    Saturn's vast E-ring engulfs the satellites Mimas, Enceladus, Tethys, Dione, and Rea, reaching even beyond Titan, while its inner edge is adjacent with the outskirts of the A-ring. The E-ring is comprised of characteristically micron and submicron sized particles, originating mainly from the active plumes of Enceladus, and possibly the other moons as well due to their continual bombardment by interplanetary dust particles. The dynamics of the E-ring grains can be surprising as in addition to the gravity of Saturn and its moons, their motion is governed by radiation pressure, plasma drag, and electromagnetic forces as they collect charges interacting with the magnetospheric plasma environment of Saturn. Due to sputtering, their mass is diminishing and, hence, their charge-to-mass ratio is increasing in time. A "young" gravitationally dominated micron-sized particle will "mature" into a nanometer-sized grain whose motion resembles that of a heavy ion. Simultaneously with their mass loss, the dust particles are pushed outwards by plasma drag. Time to time, their evolving orbits intersect the orbits of the Saturnian moons and the E-ring particles can be deposited onto their surfaces, possibly altering their makeup and spectral properties. Using the Cassini magnetospheric observations, we have followed the orbital evolution of E-ring particles, through their entire life, starting at Enceladus, ending in: a) a collision with the A-ring or any of the satellites; or b) losing all their mass due to sputtering; or c) leave the magnetosphere of Saturn. This presentation will focus on the deposition rates and maps of E-ring particles to the surfaces of the moons.

  10. Extended Survey of Saturn Z/O-mode Wave Intensity

    Science.gov (United States)

    Menietti, J. D.; Averkamp, T. F.; Ye, S.; Kurth, W. S.

    2016-12-01

    The role of Z-mode emission in the diffusive scattering and resonant acceleration of electrons is believed to be important. A survey of the "5 kHz" component of this emission at Saturn indicates strong intensity in the lower density regions where fp/fc spatial coordinates. The goal is to parameterize these data for use in quasilinear models requiring thecalculation of pitch angle and momentum diffusion coefficients. In this report we present our initial results.

  11. On-line optimization code used at Saturne

    Science.gov (United States)

    Lagniel, J. M.; Lemaire, J. L.

    A computer code has been developped in order to make the tuning of the injection process easier in the Saturne synchrotron accelerator and search for sets of new values of parameters leading to the optimum of any criterion. The usual criterion being mainly the beam intensity given by current transformers or any non-destructive measurement device. Acquisition of the criterion is made at each cycle of the acceleration. The technique used has many advantages

  12. The vertical structure of Jupiter and Saturn zonal winds from nonlinear simulations of major vortices and planetary-scale disturbances

    Science.gov (United States)

    Garcia-Melendo, E.; Legarreta, J.; Sanchez-Lavega, A.

    2012-12-01

    Direct measurements of the structure of the zonal winds of Jupiter and Saturn below the upper cloud layer are very difficult to retrieve. Except from the vertical profile at a Jupiter hot spot obtained from the Galileo probe in 1995 and measurements from cloud tracking by Cassini instruments just below the upper cloud, no other data are available. We present here our inferences of the vertical structure of Jupiter and Saturn zonal wind across the upper troposphere (deep down to about 10 bar level) obtained from nonlinear simulations using the EPIC code of the stability and interactions of large-scale vortices and planetary-scale disturbances in both planets. Acknowledgements: This work has been funded by Spanish MICIIN AYA2009-10701 with FEDER support, Grupos Gobierno Vasco IT-464-07 and UPV/EHU UFI11/55. [1] García-Melendo E., Sánchez-Lavega A., Dowling T.., Icarus, 176, 272-282 (2005). [2] García-Melendo E., Sánchez-Lavega A., Hueso R., Icarus, 191, 665-677 (2007). [3] Sánchez-Lavega A., et al., Nature, 451, 437- 440 (2008). [4] Sánchez-Lavega A., et al., Nature, 475, 71-74 (2011).

  13. Ray-tracing temperatures of the Main Rings of Saturn

    Science.gov (United States)

    Flandes, Alberto; García, Ángel; Deau, Estelle; Spilker, Linda

    2017-10-01

    The temperature of the main rings of Saturn is strongly dependent upon the distribution and the general structure of the ensembles of particles that compose them, mainly due to shadowing effects that modulate how much energy reaches the individual particles granted that the direct solar energy is the main driver of the rings' temperature-. In this work we separate the main rings (A, CD, B and C) in 13 different regions along the radial direction and, based on the average properties of the structure of these regions derived from the Cassini UVIS observations, we simulate them using lambertian spherical particles. These simulations are then used to derive their shadowed/non-shadowed fractional areas as the solar elevation angle varies and then their temperature variation with the same angle. For this purpose we use a semi-analytical model where four energy sources are considered (solar direct and Saturn reflected energy, Saturn thermal energy and particles' thermal energies). The synthetic temperature results are compared to the Cassini measured temperatures (from -22 deg to equinox) with good agreement.

  14. A belt of moonlets in Saturn's A ring.

    Science.gov (United States)

    Sremcević, Miodrag; Schmidt, Jürgen; Salo, Heikki; Seiss, Martin; Spahn, Frank; Albers, Nicole

    2007-10-25

    The origin and evolution of planetary rings is one of the prominent unsolved problems of planetary sciences, with direct implications for planet-forming processes in pre-planetary disks. The recent detection of four propeller-shaped features in Saturn's A ring proved the presence of large boulder-sized moonlets in the rings. Their existence favours ring creation in a catastrophic disruption of an icy satellite rather than a co-genetic origin with Saturn, because bodies of this size are unlikely to have accreted inside the rings. Here we report the detection of eight new propeller features in an image sequence that covers the complete A ring, indicating embedded moonlets with radii between 30 m and 70 m. We show that the moonlets found are concentrated in a narrow 3,000-km-wide annulus 130,000 km from Saturn. Compared to the main population of ring particles (radius s ring-moon of Pan size or larger, locally contributing new material to the older ring. This supports the theory of catastrophic ring creation in a collisional cascade.

  15. Cassini Begins Close-Up Examination of Saturn System

    Science.gov (United States)

    Showstack, Randy

    2004-07-01

    The international Cassini-Huygens mission to Saturn and Titan already has returned some initial results which will help to re-write science textbooks, and some astounding images. The spacecraft entered orbit around Saturn on 30 June following a successful 96-minute engine burn as the spacecraft flew between the planet's F and G rings. Robert Mitchell, the Cassini program manager with the Jet Propulsion Laboratory, said the spacecraft could have been damaged if it had been hit by a grain of dust the size of a pea while crossing through the ring plane. Prior to the burn, he said flight controllers would ``chew their nails'' in nervousness as they awaited indication that the Saturn orbit insertion was successful. Mitchell added that the spacecraft did not fly through the rings due to any sort of scientific preference, but rather that the flyby was ``a combination of getting close enough to make the propellant cost one we could afford, and still be in a region as safe as we could make it.''

  16. Quasiperiodic ULF-pulsations in Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. Kleindienst

    2009-02-01

    Full Text Available Recent magnetic field investigations made onboard the Cassini spacecraft in the magnetosphere of Saturn show the existence of a variety of ultra low frequency plasma waves. Their frequencies suggest that they are presumably not eigenoscillations of the entire magnetospheric system, but excitations confined to selected regions of the magnetosphere. While the main magnetic field of Saturn shows a distinct large scale modulation of approximately 2 nT with a periodicity close to Saturn's rotation period, these ULF pulsations are less obvious superimposed oscillations with an amplitude generally not larger than 3 nT and show a package-like structure. We have analyzed these wave packages and found that they are correlated to a certain extent with the large scale modulation of the main magnetic field. The spatial localization of the ULF wave activity is represented with respect to local time and Kronographic coordinates. For this purpose we introduce a method to correct the Kronographic longitude with respect to a rotation period different from its IAU definition. The observed wave packages occur in all magnetospheric regions independent of local time, elevation, or radial distance. Independent of the longitude correction applied the wave packages do not occur in an accentuated Kronographic longitude range, which implies that the waves are not excited or confined in the same selected longitude ranges at all times or that their lifetime leads to a variable phase with respect to the longitudes where they have been exited.

  17. Small particles dominate Saturn's Phoebe ring to surprisingly large distances

    Science.gov (United States)

    Hamilton, Douglas P.; Skrutskie, Michael F.; Verbiscer, Anne J.; Masci, Frank J.

    2015-06-01

    Saturn's faint outermost ring, discovered in 2009 (ref. 1), is probably formed by particles ejected from the distant moon Phoebe. The ring was detected between distances of 128 and 207 Saturn radii (RS = 60,330 kilometres) from the planet, with a full vertical extent of 40RS, making it well over ten times larger than Saturn's hitherto largest known ring, the E ring. The total radial extent of the Phoebe ring could not, however, be determined at that time, nor could particle sizes be significantly constrained. Here we report infrared imaging of the entire ring, which extends from 100RS out to a surprisingly distant 270RS. We model the orbital dynamics of ring particles launched from Phoebe, and construct theoretical power-law profiles of the particle size distribution. We find that very steep profiles fit the data best, and that elevated grain temperatures, arising because of the radiative inefficiency of the smallest grains, probably contribute to the steepness. By converting our constraint on particle sizes into a form that is independent of the uncertain size distribution, we determine that particles with radii greater than ten centimetres, whose orbits do not decay appreciably inward over 4.5 billion years, contribute at most about ten per cent to the cross-sectional area of the ring's dusty component.

  18. 3-Dimensional simulations of storm dynamics on Saturn

    Science.gov (United States)

    Hueso, R.; Sanchez-Lavega, A.

    2000-10-01

    The formation and evolution of convective clouds in the atmosphere of Saturn is investigated using an anelastic three-dimensional time-dependent model with parameterized microphysics. The model is designed to study the development of moist convection on any of the four giant planets and has been previously used to investigate the formation of water convective storms in the jovian atmosphere. The role of water and ammonia in moist convection is investigated with varying deep concentrations. Results imply that most of the convective activity observed at Saturn may occur at the ammonia cloud deck while the formation of water moist convection may happen only when very strong constraints on the lower troposphere are met. Ammonia storms can ascend to the 300 mb level with vertical velocities around 30 ms-1. The seasonal effect on the thermal profile at the upper troposphere may have important effects on the development of ammonia storms. In the cases where water storms can develop they span many scale heights with peak vertical velocities around 160 ms-1 and cloud particles can be transported up to the 150 mb level. These predicted characteristics are similar to the Great White Spots observed in Saturn which, therefore, could be originated at the water cloud base level. This work has been supported by Gobierno Vasco PI 1997-34. R. Hueso acknowledges a PhD fellowship from Gobierno Vasco.

  19. Magnetotail Reconnection and Flux Circulation: Jupiter and Saturn Compared

    Science.gov (United States)

    Jackman, C. M.; Vogt, M. F.; Slavin, J. A.; Cowley, S. W. H.; Boardsen, S. A.

    2011-01-01

    The Jovian magnetosphere has been visited by eight spacecraft, and the magnetometer data have been used to identify dozens of plasmoids and 250 field dipolarizations associated with magnetic reconnection in the tail [e.g. Vogt et al., 2010]. Since the arrival of the Cassini spacecraft at Saturn in 2004, the magnetometer instrument has also been used to identify reconnection signatures. The deepest magnetotail orbits were in 2006, and during this time 34 signatures of plasmoids were identified. In this study we compare the statistical properties of plasmoids at Jupiter and Saturn such as duration, size, location, and recurrence period. Such parameters can be influenced by many factors, including the different Dungey cycle timescales and cross-magnetospheric potential drops at the two planets. We present superposed epoch analyses of plasmoids at the two planets to determine their average properties and to infer their role in the reconfiguration of the nightside of the magnetosphere. We examine the contributions of plasmoids to the magnetic flux transfer cycle at both planets. At Jupiter, there is evidence of an extended interval after reconnection where the field remains northward (analogous to the terrestrial post-plasmoid plasma sheet). At Saturn we see a similar feature, and calculate the amount of flux closed on average in reconnection events, leading us to an estimation of the recurrence rate of plasmoid release.

  20. On the Edgeworth-Kuiper Belt dust flux to Saturn

    Science.gov (United States)

    Poppe, A. R.; Horanyi, M.

    2012-09-01

    The Edgeworth-Kuiper Belt (EKB) produces approximately 3 × 107 tons/year of dust grains with radii between 0.1 and 10.0 μm through a combination of mutual collisions and bombardment by interstellar dust grains [1]. These grains migrate inward through the outer solar system under the combination of gravity, solar radiation pressure, solar wind drag, and the electromagnetic Lorentz force, forming a tenuous dust halo extending from the orbit of Jupiter out past the classical EKB, and in turn, EKB-generated grains are believed to be the dominant species of dust from Saturn outward [2]. In this talk, we present calculations of the EKB influx into Saturn using a dynamical dustgrain tracing model that is absolutely calibrated to both New Horizons Student Dust Counter and Pioneer 10 meteoroid detector measurements. We discuss the differences of our model with previous estimates of EKB influx to Saturn, and the implications that these differences may have on a variety of phenomena in the saturnian system.

  1. Low-energy charged particles in Saturn's magnetosphere - Results from Voyager 1

    Science.gov (United States)

    Krimigis, S. M.; Bostrom, C. O.; Keath, E. P.; Carbary, J. F.; Roelof, E. C.; Armstrong, T. P.; Axford, W. I.; Gloeckler, G.; Hamilton, D. C.; Lanzerotti, L. J.

    1981-01-01

    The Voyager 1 low-energy charged particle instrument measured electrons and ions with energies below 26 and 40 kiloelectron volts, respectively, in the Saturn magnetosphere. Spectra of all ion species were found to have an energy cutoff at levels greater than 2 million electron volts. In contrast to the magnetospheres of Jupiter and earth, there are no lobe regions essentially devoid of particles in Saturn's nighttime magnetosphere. One novel feature of the Saturn magnetosphere is a pervasive population of energetic molecular hydrogen.

  2. Theory, measurements, and models of the upper atmosphere and ionosphere of Saturn

    Science.gov (United States)

    Atreya, S. K.; Donahue, T. M.; Nagy, A. F.; Waite, J. H., Jr.; Mcconnell, J. C.

    1984-01-01

    The structure and composition of the thermosphere, exosphere, and ionosphere of saturn have been determined from observations at optical and radio wavelengths mainly by instruments aboard Voyager spacecraft. Techniques for determining the vertical profiles of temperature and density and the atmospheric vertical mixing in the upper Saturn atmosphere are discussed. Radio occultation measurements and theoretical models of Saturn's ionosphere are reviewed, and attempts to interpret the measurements using the models are discussed. Finally, mechanisms of thermospheric heating are examined.

  3. VOYAGER 1&2 SATURN IRIS DERIVED NORTH/SOUTH PARAMETERS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set contains Saturn atmospheric parameters derived from spectra obtained with the Voyager infrared interferometer spectrometer (IRIS). The data set is...

  4. Telecommunications and data acquisition systems support for Voyager missions to Jupiter and Saturn, 1972-1981, prelaunch through Saturn encounter

    Science.gov (United States)

    Traxler, M. R.; Beauchamp, D. F.

    1983-01-01

    The Deep Space Network has supported the Voyager Project for approximately nine years, during which time implementation, testing, and operational support was provided. Four years of this time involved testing prior to launch; the final five years included network operations support and additional network implementation. Intensive and critical support intervals included launch and four planetary encounters. The telecommunications and data acquisition support for the Voyager Missions to Jupiter and Saturn are summarized.

  5. The Source of Planetary Period Oscillations in Saturn's Magnetosphere

    Science.gov (United States)

    Khurana, Krishan K.; Mitchell, Jonathan L.; Mueller, Ingo C. F.

    2017-04-01

    In this presentation, we resolve a three-decades old mystery of how Saturn is able to modulate its kilometric wave radiation and many field and plasma parameters at the planetary rotation period even though its magnetic field is extremely axisymmetric. Such waves emanating from the auroral regions of planets lacking solid surfaces have been used as clocks to measure the lengths of their days, because asymmetric internal magnetic fields spin-modulate wave amplitudes. A review by Carbary and Mitchell (2013, Periodicities in Saturn's magnetosphere, Reviews of Geophysics, 51, 1-30) on the topic summarized findings from over 200 research articles, on what the phenomena is, how it is manifested in a host of magnetospheric and auroral parameters; examined several proposed models and pointed out their shortcomings. The topic has now been explored in several topical international workshops, but the problem has remained unsolved so far. By quantitatively modeling the amplitudes and phases of these oscillations in the magnetic field observed by the Cassini spacecraft, we have now uncovered the generation mechanism responsible for these oscillations. We show that the observed oscillations are the manifestations of two global convectional conveyor belts excited in Saturn's upper atmosphere by auroral heating below its northern and southern auroral belts. We demonstrate that a feedback process develops in Saturn system such that the magnetosphere expends energy to drive convection in Saturn's upper stratosphere but gains back an amplified share in the form of angular momentum that it uses to enforce corotation in the magnetosphere and power its aurorae and radio waves. In essence, we have uncovered a new mechanism (convection assisted loss of angular momentum in an atmosphere) by which gaseous planets lose their angular momentum to their magnetospheres and outflowing plasma at rates far above previous predictions. We next show how the m = 1 convection system in the upper

  6. Thermostructural design of a carbon-carbon heatshield for a Jovian entry

    Science.gov (United States)

    White, M. J.; Heightland, C. N.; Dirling, R. B., Jr.

    1979-01-01

    The thermostructural response of three candidate carbon-carbon composites for the Jovian entry probe heatshield was investigated. The analysis for the three materials, Sandia Felt, Carbitex 700, and SAI 4-D weave carbon-carbon was conducted using a dual finite element approach which involved heat conduction as well as the structural response. A receding boundary due to ablation and inertial loads encountered by the probe were included. Severe cracking, circumferential and radial, and interlaminar shear failure was observed during the radiative heating pulse for the Sandia Felt and Carbitex 700 materials, respectively. The 4-D weave material showed no failures over the entire entry.

  7. Autonomous gliding entry guidance with

    Directory of Open Access Journals (Sweden)

    Guo Jie

    2015-10-01

    Full Text Available This paper presents a novel three-dimensional autonomous entry guidance for relatively high lift-to-drag ratio vehicles satisfying geographic constraints and other path constraints. The guidance is composed of onboard trajectory planning and robust trajectory tracking. For trajectory planning, a longitudinal sub-planner is introduced to generate a feasible drag-versus-energy profile by using the interpolation between upper boundary and lower boundary of entry corridor to get the desired trajectory length. The associated magnitude of the bank angle can be specified by drag profile, while the sign of bank angle is determined by lateral sub-planner. Two-reverse mode is utilized to satisfy waypoint constraints and dynamic heading error corridor is utilized to satisfy no-fly zone constraints. The longitudinal and lateral sub-planners are iteratively employed until all of the path constraints are satisfied. For trajectory tracking, a novel tracking law based on the active disturbance rejection control is introduced. Finally, adaptability tests and Monte Carlo simulations of the entry guidance approach are performed. Results show that the proposed entry guidance approach can adapt to different entry missions and is able to make the vehicle reach the prescribed target point precisely in spite of geographic constraints.

  8. Saturn's Ionospheric Clock(s): A Concept for Generating and Maintaining Saturn's Observed Magnetospheric Periodicities

    Science.gov (United States)

    Mitchell, D. G.; Brandt, P. C.; Ukhorskiy, A. Y.

    2010-12-01

    Saturn’s 10.X hour periodicity, observed throughout the magnetosphere, remains a mystery. It has been observed in many regions, modulating many phenomena. During the Cassini mission most observations have shown a period at about 10.8 hours, expressed in Saturn kilometric radiation from the high latitude auroral zone, in magnetic field components (both equatorial and high latitude) from 3 to 12 Rs, in current sheet encounters in the outer magnetosphere and magnetotail, in energetic neutral atom emission from the equatorial magnetosphere, and in plasma and energetic particles throughout the magnetosphere. More recently, various authors have shown at least two dominant periods expressed (in SKR and in magnetic field components), with slightly different values in the southern and northern hemispheres. The cause of this behavior is still not accounted for. Although loosely associated with Saturn’s rotation, the variability in the period precludes a direct connection with Saturn’s interior (e.g., a magnetic anomaly). Other candidates that have been discussed by others are an ionospheric source (conductivity anomaly), a perturbation in the cold plasma circulation pattern, a magnetospheric cam, asymmetric ring current particle pressure, and/or a natural frequency of the magnetosphere (cavity mode or traveling wave front of some sort). In this paper we present a concept that derives its energy from the subcorotating cold, dense plasma (which exhibits a rotation period on the order of 13 to 14 hours throughout L-shells between ~3 and 20), but is triggered by a process linked with the ionosphere. Key components of the model include significant slippage between the ionosphere and the magnetosphere (with the ionosphere rotating at the expressed period in each hemisphere, only slightly more slowly than the planet interior), subcorotating cold dense plasma with a source in the inner magnetosphere, predominantly radial transport of the cold dense plasma in the rotational

  9. Constraints on atmospheric structure and helium abundance of Saturn from Cassini/UVIS and CIRS

    Science.gov (United States)

    Koskinen, Tommi; Guerlet, Sandrine

    2017-10-01

    We combine results from stellar occultations observed by Cassini/UVIS and infrared emissions observed by Cassini/CIRS to create empirical models of atmospheric structure on Saturn corresponding to the locations probed by the UVIS stellar occultations. These models span multiple occultation locations at different latitudes from 2005 to the end of 2015. In summary, we connect the temperature-pressure profiles retrieved from the CIRS data to the temperature-pressure profiles in the thermosphere retrieved from the occultations. A corresponding altitude scale is calculated and matched to the altitude scale of the density profiles that are retrieved directly from the occultations. In addition to the temperature structure, our ability to match the altitudes in the occultation light curves depends on the mean molecular weight of the atmosphere. We use the UVIS occultations to constrain the abundance of methane near the homopause, allowing us to constrain the eddy mixing rate of the atmosphere. In addition, our preliminary results are consistent with a mixing ratio of about 11% for helium in the lower atmosphere. Our results provide an important reference for future models of Saturn’s upper atmosphere.

  10. Spacecraft entry into an atmosphere

    Science.gov (United States)

    Iaroshevskii, Vasilii A.

    Problems related to the safe entry of spacecraft into the earth or other planetary atmospheres are discussed in a general manner. Attention is given to restrictions imposed on dynamical and thermal overloads, and an analysis is made of the aerodynamic characteristics of space vehicles of different types. Analytical and semianalytical methods for calculating entry trajectories are compared, and the applicability regions of approximate solutions are determined. The discussion also covers reentry trajectory optimization problems and the principal types of perturbations and navigation and control techniques.

  11. Regulation of entry into gametogenesis.

    Science.gov (United States)

    van Werven, Folkert J; Amon, Angelika

    2011-12-27

    Gametogenesis is a fundamental aspect of sexual reproduction in eukaryotes. In the unicellular fungi Saccharomyces cerevisiae (budding yeast) and Schizosaccharomyces pombe (fission yeast), where this developmental programme has been extensively studied, entry into gametogenesis requires the convergence of multiple signals on the promoter of a master regulator. Starvation signals and cellular mating-type information promote the transcription of cell fate inducers, which in turn initiate a transcriptional cascade that propels a unique type of cell division, meiosis, and gamete morphogenesis. Here, we will provide an overview of how entry into gametogenesis is initiated in budding and fission yeast and discuss potential conserved features in the germ cell development of higher eukaryotes.

  12. Economics of entry into marriage

    OpenAIRE

    Bowmaker, Simon W.

    2009-01-01

    This thesis contains three studies on the economics of entry into marriage; a life event that has been shown to have significant implications for the well-being (economic and otherwise) of men, women and their children. The first study examines the effect of family background on the timing of first marriage of 7,853 individuals born in 1970 in Great Britain. Hazard model analysis reveals that high levels of parental resources serve to delay entry into marriage for both males and femal...

  13. Searching for Seasonal Changes in Saturn's A Ring

    Science.gov (United States)

    Brooks, S. M.; Spilker, L. J.; Pilorz, S. H.; Edgington, S. G.; Wallis, B. D.; Altobelli, N.; Ferrari, C.

    2005-12-01

    An intriguing result from Cassini's first observations of Saturn's A ring from Saturn Orbit Insertion (SOI), was the lack of a temperature contrast between the ring's illuminated and unilluminated sides [1]. Determined from observations taken by Cassini's Composite Infrared Spectrometer (CIRS), this lack of contrast was unexpected, as direct solar heating is the largest factor in maintaining the rings' heat budget. Observations taken with the Infrared Radiometer and Spectrometer (IRIS) onboard Voyager 1, however, yield a temperature difference of ~ 5 - 10 K . CIRS observations would easily have revealed such a difference. Additionally, Voyager 1 temperatures are some 15 - 25 K colder than those measured at SOI. One explanation for this is seasonal changes in solar insolation. In 1980 Voyager 1 flew past Saturn after northern vernal equinox, when the solar inclination angle was just 4° . At SOI the Sun was 24° above the ring plane. Since then the Sun has dropped ~ 3° lower. Temperature contrasts have appeared in data taken since April 2005. However, whereas unlit ring temperatures are lower, lit side ring temperatures are now higher, suggesting that solar inclination angle is not the only factor involved. Indeed, observations taken since SOI have clearly shown that the observed temperature profile of the rings is a strong function of observing geometry. The temperature profile changes with phase angle, emission angle and local hour angle. Yet, the large temperature differences between SOI and the Voyager flybys seem most likely due to the change in Saturnian season. We will interpret CIRS A ring observations in the context of Voyager IRIS observations. And, we will attempt to determine to what extent the observed ring temperatures have been driven by the changing solar inclination angle, using ring thermal models and recent Cassini observations to sort out the effects of observation geometry. [1] F.M. Flasar, et al. 2005. ``Science'', vol. 307, pgs. 1247-1251.

  14. Saturn's equatorial jet structure from Cassini/ISS

    Science.gov (United States)

    García-Melendo, Enrique; Legarreta, Jon; Sánchez-Lavega, Agustín.; Pérez-Hoyos, Santiago; Hueso, Ricardo

    2010-05-01

    Detailed wind observations of the equatorial regions of the gaseous giant planets, Jupiter and Saturn, are crucial for understanding the basic problem of the global circulation and obtaining new detailed information on atmospheric phenomena. In this work we present high resolution data of Saturn's equatorial region wind profile from Cassini/ISS images. To retrieve wind measurements we applied an automatic cross correlator to image pairs taken by Cassini/ISS with the MT1, MT2, MT3 filters centred at the respective three methane absorbing bands of 619nm, 727nm, and 889nm, and with the adjacent continuum CB1, CB2, and CB3 filters. We obtained a complete high resolution coverage of Saturn's wind profile in the equatorial region. The equatorial jet displays an overall symmetric structure similar to that shown the by same region in Jupiter. This result suggests that, in accordance to some of the latest compressible atmosphere computer models, probably global winds in gaseous giants are deeply rooted in the molecular hydrogen layer. Wind profiles in the methane absorbing bands show the effect of strong vertical shear, ~40m/s per scale height, confirming previous results and an important decay in the wind intensity since the Voyager era (~100 m/s in the continuum and ~200 m/s in the methane absorbing band). We also report the discovery of a new feature, a very strong and narrow jet on the equator, about only 5 degrees wide, that despite the vertical shear maintains its intensity (~420 m/s) in both, the continuum and methane absorbing band filters. Acknowledgements: Work supported by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07.

  15. Saturn ring temperature changes before and after ring equinox

    Science.gov (United States)

    Spilker, Linda; Flandes, Alberto; Morishima, Ryuji; Leyrat, Cedric; Altobelli, Nicolas; Ferrari, Cecile; Brooks, Shawn; Pilorz, Stu

    2010-05-01

    The Cassini Composite infrared spectrometer (CIRS) retrieved the temperatures of Saturn's main rings at solar elevations ranging from 24 degrees to zero degrees at equinox (August 2009) as the sun traversed from the south to north side of the rings. Over this broad range of solar elevation the CIRS data show that the ring temperatures vary as much as 29K- 38K for the A ring, 22K-34K for the B ring and 18K-23K for the C ring. Interestingly the unlit sides of the rings show a similar decrease in temperature with the decreasing solar elevation. As equinox approached, the main rings cooled to their lowest temperatures measured to date. At equinox the solar input is very small and the primary heat sources for the rings are Saturn thermal and visible energy. Temperatures are almost identical for similar geometries on the north and south sides of the rings. The ring temperatures at equinox were: C ring, 55-75 K; B ring, 45-60 K; Cassini Division, 45 - 58 K; and A ring, 43 - 52 K. After Saturn equinox the solar elevation angle began to increase again and the temperatures on both the lit (north) and unlit (south) sides of the rings have begun to increase as well. Ring thermal models developed by Flandes and Morishima are able to reproduce most of the equinox temperatures observed by CIRS. Results before and after equinox will be presented. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA and at CEA Saclay supported by the "Programme National de Planetologie". Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

  16. The Pole Orientation, Pole Precession, and Moment of Inertia Factor of Saturn

    Science.gov (United States)

    Jacobson, R. A.; French, R. G.; Nicholson, P. D.; Hedman, M.; Colwell, J. E.; Marouf, E.; Rappaport, N.; McGhee, C.; Sepersky, T.; Lonergan, K.

    2011-01-01

    This paper discusses our determination of the Saturn's pole orientation and precession using a combination of Earthbased and spacecraft based observational data. From our model of the polar motion and the observed precession rate we obtain a value for Saturn's polar moment of inertia

  17. Analysis of Stellar Occultation and Imaging Data for the Rings of Saturn and Uranus

    Science.gov (United States)

    Nicholson, Philip D.

    1998-01-01

    The principal goals of this research were as follows: 1. To carry out photometric modelling of Saturn's B Ring; 2. To re-examine dynamical perturbations of the Uranian c ring, 'While delivering relevant occultation data to the PDS Rings Node; and 3. Prepare data from the Saturn ring-plane crossing observations for delivery to the Rings Node.

  18. A report of advancements in structural dynamic technology resulting from Saturn 5 programs

    Science.gov (United States)

    1970-01-01

    Two volume report on practical aspects of structural dynamic analysis in Saturn 5 program is described. Volume 1 is oriented toward program managers of future structural dynamic programs. Volume 2, oriented toward technical leaders of programs, discusses methods and procedures used in Saturn 5 program.

  19. Energetic electron fluxes at Saturn from Cassini observations

    Science.gov (United States)

    Tang, Rongxin; Summers, Danny

    2012-06-01

    Energetic electron fluxes (18 keV-21 MeV) observed by the MIMI/LEMMS instrument on the Cassini mission during 2004 to 2008 are analyzed. We consider all 101 orbits and we select portions of the orbits that lie within 0.5 RS of the magnetic equatorial plane, where RS is Saturn's radius. We determine the average electron differential flux and integral flux at specified L-shells in the range 4.5 Kennel-Petschek theory. We find that at lower L-shells, L Kennel-Petschek limit; and at larger L-shells, 7 Kennel-Petschek limit.

  20. Regolith Growth and Darkening of Saturn Ring Particles

    Science.gov (United States)

    Esposito, L. W.; Elliott, J. P.

    2009-04-01

    Markov chain simulations compare the regolith growth and darkening on 1 m and 10m particles in Saturn's rings. Our results show that pollution of the larger ring particles is ten times slower, allowing the rings to be ancient and still meet strict upper limits on fractional pollution by meteoroid infall. Example UV spectra are shown. Our results indicate that regolith stirring by higher velocity collisions can mix the ring particle regolith, creating brighter haloes around strong density waves, as observed by Cassini VIMS and UVIS. Unfortunately, our incomplete knowledge of meteoritic bombardment rates, particle adhesion and size/velocity distributions do not allow an age estimate.

  1. Regolith Growth and Darkening of Saturn's Ring Particles

    Science.gov (United States)

    Esposito, L. W.; Elliott, J. P.; Albers, N.

    2008-12-01

    Markov chain simulations compare the regolith growth and darkening on 1 m and 10m particles in Saturn's rings. Our results show that pollution of the larger ring particles is ten times slower, allowing the rings to be ancient and still meet strict upper limits on fractional pollution by meteoroid infall. Example UV spectra are shown. Our results indicate that regolith stirring by higher velocity collisions can mix the ring particle regolith, creating brighter haloes around strong density waves, as observed by Cassini VIMS and UVIS. Unfortunately, our incomplete knowledge of meteoritic bombardment rates, particle adhesion and size/velocity distributions do not allow an age estimate.

  2. Saturn's rings - Particle size distributions for thin layer model

    Science.gov (United States)

    Zebker, H. A.; Marouf, E. A.; Tyler, G. L.

    1985-01-01

    A model incorporating limited interaction between the incident energy and particles in the ring is considered which appears to be consistent with the multiple scattering process in Saturn's rings. The model allows for the small physical thickness of the rings and can be used to relate Voyager 1 observations of 3.6- and 13-cm wavelength microwave scatter from the rings to the ring particle size distribution function for particles with radii ranging from 0.001 to 20 m. This limited-scatter model yields solutions for particle size distribution functions for eight regions in the rings, which exhibit approximately inverse-cubic power-law behavior.

  3. JANNAF Lessons Learned Panel: Selected Saturn V History

    Science.gov (United States)

    Urquhart, Skip

    2010-01-01

    Pogo occurs when the natural frequency of a propellant feed line comes close to a readily excited rocket longitudinal structural vibration natural frequency. Maximum Pogo response corresponds to close tuning of the structural and hydraulic frequencies. On Saturn V, accelerations up to 17 g's (Zero To Peak) at the Launch Vehicle/Payload Interface and up to 34 g's at an Engine have been observed. Nicknamed Pogo because it causes the Rocket to stretch and compress like a Pogo stick. First recognized with the Titan II in 1962, Pogo remains a prime consideration in design of launch vehicles today

  4. Direct detection of gaps in Saturn's A ring

    Science.gov (United States)

    Rehnberg, Morgan E.; Brown, Zarah L.; Esposito, Larry W.; Albers, Nicole

    2017-11-01

    Indirect observations spanning decades have indicated that Saturn's A ring is populated with a plethora of self-gravity wakes, small wavelike structures that arise from the gravitational attraction between ring particles. We present the direct detection of the gaps that represent the minima between the denser wakes. Through a statistical test, we analyze a series of seven high-resolution stellar occultations observed by the Cassini Ultraviolet Imaging Spectrograph to identify nearly half a million discrete regions with an optical depth less than a quarter of the surrounding ring. These gaps correlate strongly with previous observations of the A-ring brightness asymmetry.

  5. Large and small-scale structures in Saturn's rings

    Science.gov (United States)

    Albers, N.; Rehnberg, M. E.; Brown, Z. L.; Sremcevic, M.; Esposito, L. W.

    2017-09-01

    Observations made by the Cassini spacecraft have revealed both large and small scale structures in Saturn's rings in unprecedented detail. Analysis of high-resolution measurements by the Cassini Ultraviolet Spectrograph (UVIS) High Speed Photometer (HSP) and the Imaging Science Subsystem (ISS) show an abundance of intrinsic small-scale structures (or clumping) seen across the entire ring system. These include self-gravity wakes (50-100m), sub-km structure at the A and B ring edges, and "straw"/"ropy" structures (1-3km).

  6. Saturn's Rings: Pre-Cassini Status and Mission Goals

    Science.gov (United States)

    Cuzzi, Jeffrey N.; Colwell, J. E.; Esposito, L. W.; Porco, C. C.; Murray, C. D.; Nicholson, P. D.; Spilker, L.; Marouf, E. A.; French, R. C.; Rappaport, N.; hide

    2001-01-01

    Theoretical and observational progress in studies of Saturn's ring system since the mid-1980s is reviewed, focussing on advances in configuration and dynamics, composition and size distribution, dust and meteoroids, interactions of the rings with the planet and the magnetosphere, and relationships between the rings and various satellites. The Cassini instrument suite of greatest relevance to ring studies is also summarized, emphasizing how the individual instruments might work together to solve outstanding problems. The Cassini tour is described from the standpoint of ring studies, and major ring science goals are summarized.

  7. A wave dynamical interpretation of Saturn's polar hexagon

    Science.gov (United States)

    Allison, M.; Godfrey, D. A.; Beebe, R. F.

    1990-01-01

    The hexagonal, pole-centered cloud feature in Saturn's northern atmosphere, as revealed in Voyager close-encounter imaging mosaics, may be interpreted as a stationary Rossby wave. The wave is embedded within a sharply peaked eastward jet (of 100 meters per second) and appears to be perturbed by at least one anticyclonic oval vortex immediately to the south. The effectively exact observational determination of the horizontal wave number and phase speed, applied to a simple model dispersion relation, suggests that the wave is vertically trapped and provides a diagnostic template for further modeling of the deep atmospheric stratification.

  8. Interstellar Organics, the Solar Nebula, and Saturn's Satellite Phoebe

    Science.gov (United States)

    Pendleton, Y. J.; Cruikshank, D. P.

    2014-01-01

    The diffuse interstellar medium inventory of organic material (Pendleton et al. 1994, Pendleton & Allamandola 2002) was likely incorporated into the molecular cloud in which the solar nebula condensed. This provided the feedstock for the formation of the Sun, major planets, and the smaller icy bodies in the region outside Neptune's orbit (transneptunian objects, or TNOs). Saturn's satellites Phoebe, Iapetus, and Hyperion open a window to the composition of one class of TNO as revealed by the near-infrared mapping spectrometer (VIMS) on the Cassini spacecraft at Saturn. Phoebe (mean diameter 213 km) is a former TNO now orbiting Saurn. VIMS spaectral maps of PHoebe's surface reveal a complex organic spectral signature consisting of prominent aromatic (CH) and alophatic hydrocarbon (CH2, CH3) absorption bands (3.2-3.6 micrometers). Phoebe is the source of a huge debris ring encircling Saturn, and from which particles (approximately 5-20 micrometer size) spiral inward toward Saturn. They encounter Iapetus and Hperion where they mix with and blanket the native H2O ice of those two bodies. Quantitative analysis of the hydrocarbon bands on Iapetus demonstrates that aromatic CH is approximately 10 times as abundant as aliphatic CH2+CH3, significantly exceeding the strength of the aromatic signature in interplanetary dust particles, comet particles, ad in carbonaceous meteorites (Cruikshank et al. 2013). A similar excess of aromatics over aliphatics is seen in the qualitative analysis of Hyperion and Phoebe itself (Dalle Ore et al. 2012). The Iapetus aliphatic hydrocarbons show CH2/CH3 approximately 4, which is larger than the value found in the diffuse ISM (approximately 2-2.5). In so far as Phoebe is a primitive body that formed in the outer regions of the solar nebula and has preserved some of the original nebula inventory, it can be key to understanding the content and degree of procesing of the nebular material. There are other Phoebe-like TNOs that are presently

  9. Sharp Edges in Saturn's Rings: Radial Structure and Longitudinal Variability

    Science.gov (United States)

    Colwell, Joshua E.; Jerousek, R. G.; Esposito, L. W.

    2010-10-01

    The Cassini Ultraviolet Imaging Spectrograph has observed more than 100 occultations of stars by Saturn's rings with a typical ring plane radial resolution of preventing a fit from our smooth model. We find that the radial scale, characterized by a sigmoid function, over which the ring optical depth declines is typically 10-20 m. We are unable to place a tight constraint on the vertical thickness of the ring, however, because the light curve is dominated by the scale of the radial variation. We find large variability in the structure of the edges with no clear correlation to known possible perturbers in the system.

  10. Entry Facilitation by Environmental Groups

    NARCIS (Netherlands)

    van der Made, Allard; Schoonbeek, Lambert

    We consider a model of vertical product differentiation where consumers care about the environmental damage their consumption causes. An environmental group is capable of increasing consumers' environmental concern via a costly campaign. We show that the prospect of such a campaign can induce entry

  11. Phoebus: A Hypervelocity Entry Demonstrator

    Science.gov (United States)

    Ferracina, L.; Marraffa, L.; Longo, J.

    2012-12-01

    ESA is today considering various missions, such as Marco Polo R and (Moon of) Mars Sample Return, requiring capsules re-entering the Earth atmosphere at speeds up to 13 km/s.To mature critical high speed re-entry technologies and consequently to speed-up the development and reduce the development cost (and cost uncertainties) for future sample return mission, an in-flight technology demonstrator, named PHOEBUS (Project for a High- speed Of Entry Ballistic multi-User System), is presently under investigation at the European Space Research and Technology Centre (ESTEC) of ESA.This paper focuses on the preliminary aerothermodynamics feasibility assessment conducted within the Concurrent Design Facility (CDF) study at ESA-ESTEC for the design of the PHOEBUS re-entry capsule starting from a parametric analysis of the entry phase to enable a preliminary design and a baseline configuration selection and concluded with non- equilibrium reacting flow computations coupled with radiation and transport simulations to estimate the heat flux experience by the TPS at few selected trajectory points.

  12. Forcing Entry into the Nucleus.

    Science.gov (United States)

    Lomakin, Alexis; Nader, Guilherme; Piel, Matthieu

    2017-12-04

    Nuclear pore complexes tightly regulate nucleo-cytoplasmic transport, controlling the nuclear concentration of several transcription factors. In a recent issue of Cell, Elosegui-Artola et al. (2017) show that nuclear deformation modulates the nuclear entry rates of YAP/TAZ via nuclear pore stretching, clarifying how forces affect gene transcription. Copyright © 2017. Published by Elsevier Inc.

  13. The electrons and ion characteristics of Saturn's plasma disk inside the Enceladus orbit

    Science.gov (United States)

    Morooka, Michiko; Wahlund, Jan-Erik; Ye, Sheng-Yi; Kurth, William; Persoon, Ann; Holmberg, Mika

    2017-04-01

    Cassini observations revealed that Saturn's icy moon Enceladus and surrounding E ring are the significant plasma source of the magnetosphere. However, the observations sometimes show the electron density enhancement even inside the Enceladus orbiting distance, 4RS. Further plasma contribution from the inner rings, the G and the F rings and main A ring are the natural candidate as an additional plasma source. The Cassini/RPWS Langmuir Probe (LP) measurement provides the characteristics of the electrons and ions independently in a cold dense plasma. The observations near the center of the E ring showed that the ion density being larger than the electron density, indicating that there is additional particle as a negative charge carrier. Those are the small nm and μm sized dust grains that are negatively charged by the electron attachments. The faint F and G rings, located at R=2RS and 3RS, consist of small grains and similar electron/ion density discrepancies can be expected. We will show different types of the LP observations when Cassini traveled the equator region of the plasma disk down to 3RS. One with the electron density increasing inside 4RS, and another with the electron density decreasing inside 4RS. During the orbit 016 (2005 doy-284/285), the electron density continued to increase toward the planet. On the other hand, the ion currents, the LP measured currents from the negative bias voltage, turn to decreasing inside 4RS, implying the density decrease of the ions. By comparing the observed LP ion current characteristics and the modeled values using the obtained electron density, we found that the characteristic ion mass can be several times larger than the water ions (AMU=18) that we expected in this region. During the orbit 015 (2005 doy-266/267), on the other hand, the LP observed sharp electron density drop near 3RS. The dust signals from the RPWS antenna showed the density enhancement of the μm sized grains coincide the electron density drop and we

  14. Evaluation of fluid flow in the lower core of a PWR with Code-Saturne

    Energy Technology Data Exchange (ETDEWEB)

    Yvan Fournier; Celine Bechaud [EDF R et D, Fluid Mechanics and Heat Transfer 6 quai Watier, 78400 Chatou (France)

    2005-07-01

    Full text of publication follows: In order to better understand the stresses to which fuel rods are subjected, we need to improve our knowledge of the fluid flow inside the core. We are particularly interested in the first spacer grid region, as fuel rod fretting has sometimes been observed at that level. Entry conditions depend on the geometry of the lower core plate, of the assembly nozzles. Distribution of flow in the downcomer and lower plenum is also a factor. A series of calculations are thus run with our incompressible Navier-Stokes solver, Code-Saturne, using a classical RANS turbulence model. The first calculations involve a global geometry, including part of the cold legs, downcomer, lower plenum, and lower core of a pressurized water reactor. The level of detail includes most obstacles below the core. The lower core plate, being pierced with close to 800 holes, cannot be well represented within a practical mesh size, so that a head loss model is used. The lower core itself requiring even more detail is also represented with head losses. We make full use of Code-Saturne 's non conforming mesh possibilities to represent a complex geometry, being careful to retain a good mesh quality. Starting just under the lower core, the mesh is aligned with fuel rod assemblies, so that different types of assemblies can be represented through different head loss coefficients. These calculations yield steady-state or near steady-state results, which should be sufficient to yield realistic entry conditions for full core calculations at assembly width resolution, and beyond those mechanical strain calculations. We are especially interested in more detailed flow conditions and in the lower core area, so as in the future to quantify vibrational input. This requires a much higher resolution, which we limit to a scale of a few assemblies for practical reasons. At this scale, most of the features of the fuel rods, nozzles, and guide tubes are represented, though the

  15. Atmospheric structure from Phoenix atmospheric entry data

    Science.gov (United States)

    Catling, D. C.

    2008-12-01

    The atmospheric structure at the time of landing of NASA's Phoenix probe has been derived from measurements of the aerodynamic drag of the spacecraft during atmospheric entry and descent. The result provides the first atmospheric structure in Mars' polar environment obtained from in situ measurements. Phoenix was equipped with an inertial measurement unit (IMU) that used accelerometers for linear acceleration measurement in three Cartesian axes and ring-laser gyroscopes to measure the three- dimensional orientation of the probe (Taylor et al., 2008). The temperature structure of the atmosphere along the flight path was calculated via a four-step process: (i) integrating forward the IMU data to obtain the time history of the spacecraft velocity vector relative to the atmosphere as a function of altitude; (ii) calculating atmospheric density from drag, with iteration for aerodynamic coefficient dependence on density; (iii) integrating the hydrostatic equation to derive the vertical pressure; and (iv) calculating atmospheric temperature from the equation of state. Initial profile reconstruction shows reasonable agreement with predictions in the middle atmosphere for the given season and time of day (landing occurred at 16h 33min 37sec in local solar time expressed as a 24-hour clock). However, the derived lower atmospheric structure below ~0.1 mbar is generally warmer than predicted. A possible explanation could be a shallower vertical distribution of dust that usually assumed. References: P. A. Taylor, D. C. Catling, M. Daly, C. S. Dickinson, H. O. Gunnlaugsson, A-M. Harri, C. F. Lange, Temperature, pressure and wind instrumentation on the Phoenix meteorological package, J. Geophys. Res., 113, EA0A10, doi:10.1029/2007JE003015, 2008.

  16. Compositional mapping of Saturn's satellite Dione with Cassini VIMS and implications of dark material in the Saturn system

    Science.gov (United States)

    Clark, R.N.; Curchin, J.M.; Jaumann, R.; Cruikshank, D.P.; Brown, R.H.; Hoefen, T.M.; Stephan, K.; Moore, Johnnie N.; Buratti, B.J.; Baines, K.H.; Nicholson, P.D.; Nelson, R.M.

    2008-01-01

    Cassini VIMS has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. A very close fly-by of Dione provided key information for solving the riddle of the origin of the dark material in the Saturn system. The Dione VIMS data show a pattern of bombardment of fine, sub-0.5-??m diameter particles impacting the satellite from the trailing side direction. Multiple lines of evidence point to an external origin for the dark material on Dione, including the global spatial pattern of dark material, local patterns including crater and cliff walls shielding implantation on slopes facing away from the trailing side, exposing clean ice, and slopes facing the trailing direction which show higher abundances of dark material. Multiple spectral features of the dark material match those seen on Phoebe, Iapetus, Hyperion, Epimetheus and the F-ring, implying the material has a common composition throughout the Saturn system. However, the exact composition of the dark material remains a mystery, except that bound water and, tentatively, ammonia are detected, and there is evidence both for and against cyanide compounds. Exact identification of composition requires additional laboratory work. A blue scattering peak with a strong UV-visible absorption is observed in spectra of all satellites which contain dark material, and the cause is Rayleigh scattering, again pointing to a common origin. The Rayleigh scattering effect is confirmed with laboratory experiments using ice and 0.2-??m diameter carbon grains when the carbon abundance is less than about 2% by weight. Rayleigh scattering in solids is also confirmed in naturally occurring terrestrial rocks, and in previously published reflectance studies. The spatial pattern, Rayleigh scattering effect, and spectral properties argue that the dark material is only a thin coating on Dione's surface, and by extension is only a thin coating on Phoebe, Hyperion, and Iapetus, although the dark material abundance

  17. Analysis of plasma waves observed in the inner Saturn magnetosphere

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2008-09-01

    Full Text Available Plasma waves observed in the Saturn magnetosphere provide an indication of the plasma population present in the rotationally dominated inner magnetosphere. Electrostatic cyclotron emissions often with harmonics and whistler mode emission are a common feature of Saturn's inner magnetosphere. The electron observations for a region near 5 RS outside and near a plasma injection region indicate a cooler low-energy (<100 eV, nearly isotropic plasma, and a much warmer (E>1000 eV more pancake or butterfly distribution. We model the electron plasma distributions to conduct a linear dispersion analysis of the wave modes. The results suggest that the electrostatic electron cyclotron emissions can be generated by phase space density gradients associated with a loss cone that may be up to 20° wide. This loss cone is sometimes, but not always, observed because the field of view of the electron detectors does not include the magnetic field line at the time of the observations. The whistler mode emission can be generated by the pancake-like distribution and temperature anisotropy (T⊥/T||>1 of the warmer plasma population.

  18. Analysis of plasma waves observed in the inner Saturn magnetosphere

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2008-09-01

    Full Text Available Plasma waves observed in the Saturn magnetosphere provide an indication of the plasma population present in the rotationally dominated inner magnetosphere. Electrostatic cyclotron emissions often with harmonics and whistler mode emission are a common feature of Saturn's inner magnetosphere. The electron observations for a region near 5 RS outside and near a plasma injection region indicate a cooler low-energy (<100 eV, nearly isotropic plasma, and a much warmer (E>1000 eV more pancake or butterfly distribution. We model the electron plasma distributions to conduct a linear dispersion analysis of the wave modes. The results suggest that the electrostatic electron cyclotron emissions can be generated by phase space density gradients associated with a loss cone that may be up to 20° wide. This loss cone is sometimes, but not always, observed because the field of view of the electron detectors does not include the magnetic field line at the time of the observations. The whistler mode emission can be generated by the pancake-like distribution and temperature anisotropy (T/T||>1 of the warmer plasma population.

  19. Low-energy hot plasma and particles in Saturn's magnetosphere

    Science.gov (United States)

    Krimigis, S. M.; Bostrom, C. O.; Keath, E. P.; Carbary, J. F.; Roelof, E. C.; Armstrong, T. P.; Axford, W. I.; Gloeckler, G.; Hamilton, D. C.; Lanzerotti, L. J.

    1982-01-01

    Results of the low-energy charged particle experiment carried by Voyager 2 in the Saturn magnetosphere are presented. Measurements of ions of energy greater than 28 keV and electrons of energies greater than 22 keV revealed the presence of a region containing an extremely hot (30-50 keV) plasma extending from the orbit of Tethys past the orbit of Rhea, and a low-energy ion mantle inside the dayside and nightside magnetospheres. H, H2, H3, He, C and O at energies greater than 200 keV/n were found to be important constituents of the Saturn magnetosphere, at relative abundances suggestive of a solar wind origin. Low-energy electron flux enhancements were observed between the L shells of Rhea and Tethys which were absent during the Voyager 1 encounter, and persistent asymmetric electron pitch-angle distributions were noted in the outer magnetosphere in conjunction with the hot ion plasma torus. Signatures of the passage of Tethys and Enceladus through the magnetosphere were found, although not at the positions predicted by dipole magnetic field models.

  20. Stellar Occultation by Saturn's Rings in the UV

    Science.gov (United States)

    Becker, Tracy

    2017-08-01

    We propose to capitalize on the unique opportunity to observe the July 2018 stellar occultation of the star HD 168233 by Saturn's rings using the COS G230L mode on HST. Our program will characterize the particle size distribution of the rings through analyses of the starlight diffracted by the ring particles. It will also define the shape and structure of the rings through measurements of the optical depth of the variable F ring, the characterization of the self-gravity wakes, and by constraining the A ring edge dynamics six months after the radial swap of the co-orbital moons Janus and Epimetheus, which maintain the ring's outer edge. Saturn's rings are very dark at UV wavelengths; therefore, stellar occultations in the UV have a significantly lower background signal from the ring-reflected sunlight than at longer wavelengths. Furthermore, occultations at UV wavelengths are sensitive to the smallest particles in the rings. The geometry and wavelengths of the stellar occultation from HST COS will complement and extend the science return from the Cassini spacecraft nearly one year after the mission's end.

  1. Elusive Ethylene Detected in Saturns Northern Storm Region

    Science.gov (United States)

    Hesman, B. E.; Bjoraker, G. L.; Sada, P. V.; Achterberg, R. K.; Jennings, D. E.; Romani, P. N.; Lunsford, A. W.; Fletcher, L. N.; Boyle, R. J.; Simon-Miller, A. A.; hide

    2013-01-01

    The massive eruption at 40 deg. N (planetographic latitude) on Saturn in 2010 December has produced significant and lasting effects in the northern hemisphere on temperature and species abundances. The northern storm region was observed on many occasions in 2011 by Cassini's Composite Infrared Spectrometer (CIRS). In 2011 May, temperatures in the stratosphere greater than 200 K were derived from CIRS spectra in the regions referred to as "beacons" (warm regions in the stratosphere). Ethylene has been detected in the beacon region in Saturn's northern storm region using CIRS. Ground-based observations using the high-resolution spectrometer Celeste on the McMath-Pierce Telescope on 2011 May 15 were used to confirm the detection and improve the altitude resolution in the retrieved profile. The derived ethylene profile from the CIRS data gives a C2H4 mole fraction of 5.9 +/- 4.5 x 10(exp -7) at 0.5 mbar, and from Celeste data it gives 2.7 +/- 0.45 x 10(exp -6) at 0.1 mbar. This is two orders of magnitude higher than the amount measured in the ultraviolet at other latitudes prior to the storm. It is also much higher than predicted by photochemical models, indicating that perhaps another production mechanism is required or a loss mechanism is being inhibited.

  2. Proximal Probes Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Proximal Probes Facility consists of laboratories for microscopy, spectroscopy, and probing of nanostructured materials and their functional properties. At the...

  3. Airport Barriers to Entry in the US

    National Research Council Canada - National Science Library

    Dresner M; Windle R; Yao Y

    2002-01-01

    An examination is conducted on the effects of three airport barriers to entry - slot controls, gate constraints, and gate utilisation during peak operating periods - on both yields and entry in the US airline...

  4. Bi-weekly waterfowl survey data entry

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Data sheet for the entry of bi-weekly waterfowl survey data from the state of Kansas. This Excel file contains the data entry sheet and a chart displaying waterfowl...

  5. Flavivirus Entry Receptors: An Update

    Directory of Open Access Journals (Sweden)

    Manuel Perera-Lecoin

    2013-12-01

    Full Text Available Flaviviruses enter host cells by endocytosis initiated when the virus particles interact with cell surface receptors. The current model suggests that flaviviruses use at least two different sets of molecules for infectious entry: attachment factors that concentrate and/or recruit viruses on the cell surface and primary receptor(s that bind to virions and direct them to the endocytic pathway. Here, we present the currently available knowledge regarding the flavivirus receptors described so far with specific attention to C-type lectin receptors and the phosphatidylserine receptors, T-cell immunoglobulin and mucin domain (TIM and TYRO3, AXL and MER (TAM. Their role in flavivirus attachment and entry as well as their implication in the virus biology will be discussed in depth.

  6. Conceptual shape optimization of entry vehicles applied to capsules and winged fuselage vehicles

    CERN Document Server

    Dirkx, Dominic

    2017-01-01

    This book covers the parameterization of entry capsules, including Apollo capsules and planetary probes, and winged entry vehicles such as the Space Shuttle and lifting bodies. The aerodynamic modelling is based on a variety of panel methods that take shadowing into account, and it has been validated with flight and wind tunnel data of Apollo and the Space Shuttle. The shape optimization is combined with constrained trajectory analysis, and the multi-objective approach provides the engineer with a Pareto front of optimal shapes. The method detailed in Conceptual Shape Optimization of Entry Vehicles is straightforward, and the output gives the engineer insight in the effect of shape variations on trajectory performance. All applied models and algorithms used are explained in detail, allowing for reconstructing the design tool to the researcher’s requirements. Conceptual Shape Optimization of Entry Vehicles will be of interest to both researchers and graduate students in the field of aerospace engineering, an...

  7. Fragmentation and ablation during entry

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1997-09-01

    This note discusses objects that both fragment and ablate during entry, using the results of previous reports to describe the velocity, pressure, and fragmentation of entering objects. It shows that the mechanisms used there to describe the breakup of non-ablating objects during deceleration remain valid for most ablating objects. It treats coupled fragmentation and ablation during entry, building on earlier models that separately discuss the entry of objects that are hard, whose high heat of ablation permits little erosion, and those who are strong whose strength prevents fragmentation, which are discussed in ``Radiation from Hard Objects,`` ``Deceleration and Radiation of Strong, Hard, Asteroids During Atmospheric Impact,`` and ``Meteor Signature Interpretation.`` This note provides a more detailed treatment of the further breakup and separation of fragments during descent. It replaces the constraint on mass per unit area used earlier to determine the altitude and magnitude of peak power radiation with a detailed analytic solution of deceleration. Model predictions are shown to be in agreement with the key features of numerical calculations of deceleration. The model equations are solved for the altitudes of maximum radiation, which agree with numerical integrations. The model is inverted analytically to infer object size and speed from measurements of peak power and altitude to provide a complete model for the approximate inversion of meteor data.

  8. 19 CFR 122.42 - Aircraft entry.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Aircraft entry. 122.42 Section 122.42 Customs... AIR COMMERCE REGULATIONS Aircraft Entry and Entry Documents; Electronic Manifest Requirements for Passengers, Crew Members, and Non-Crew Members Onboard Commercial Aircraft Arriving In, Continuing Within...

  9. The evolution of Saturn's radiation belts modulated by changes in radial diffusion

    Science.gov (United States)

    Kollmann, P.; Roussos, E.; Kotova, A.; Paranicas, C.; Krupp, N.

    2017-12-01

    Globally magnetized planets, such as the Earth1 and Saturn2, are surrounded by radiation belts of protons and electrons with kinetic energies well into the million electronvolt range. The Earth's proton belt is supplied locally from galactic cosmic rays interacting with the atmosphere3, as well as from slow inward radial transport4. Its intensity shows a relationship with the solar cycle4,5 and abrupt dropouts due to geomagnetic storms6,7. Saturn's proton belts are simpler than the Earth's because cosmic rays are the principal source of energetic protons8 with virtually no contribution from inward transport, and these belts can therefore act as a prototype to understand more complex radiation belts. However, the time dependence of Saturn's proton belts had not been observed over sufficiently long timescales to test the driving mechanisms unambiguously. Here we analyse the evolution of Saturn's proton belts over a solar cycle using in-situ measurements from the Cassini Saturn orbiter and a numerical model. We find that the intensity in Saturn's proton radiation belts usually rises over time, interrupted by periods that last over a year for which the intensity is gradually dropping. These observations are inconsistent with predictions based on a modulation in the cosmic-ray source, as could be expected4,9 based on the evolution of the Earth's proton belts. We demonstrate that Saturn's intensity dropouts result instead from losses due to abrupt changes in magnetospheric radial diffusion.

  10. Near equality of ion phase space densities at earth, Jupiter, and Saturn

    Science.gov (United States)

    Cheng, A. F.; Krimigis, S. M.; Armstrong, T. P.

    1985-01-01

    Energetic-ion phase-space density profiles are strikingly similar in the inner magnetospheres of earth, Jupiter, and Saturn for ions of first adiabatic invariant near 100 MeV/G and small mirror latitudes. Losses occur inside L approximately equal to 7 for Jupiter and Saturn and inside L approximately equal to 5 at earth. At these L values there exist steep plasma-density gradients at all three planets, associated with the Io plasma torus at Jupiter, the Rhea-Dione-Tethys torus at Saturn, and the plasmasphere at earth. Measurements of ion flux-tube contents at Jupiter and Saturn by the low-energy charged-particle experiment show that these are similar (for O ions at L = 5-9) to those at earth (for protons at L = 2-6). Furthermore, the thermal-ion flux-tube contents from Voyager plasma-science data at Jupiter and Saturn are also very nearly equal, and again similar to those at earth, differing by less than a factor of 3 at the respective L values. The near equality of energetic and thermal ion flux-tube contents at earth, Jupiter, and Saturn suggests the possibility of strong physical analogies in the interaction between plasma and energetic particles at the plasma tori/plasma sheets of Jupiter and Saturn and the plasmasphere of earth.

  11. A Multidisciplinary Tool for Systems Analysis of Planetary Entry, Descent, and Landing (SAPE)

    Science.gov (United States)

    Samareh, Jamshid A.

    2009-01-01

    SAPE is a Python-based multidisciplinary analysis tool for systems analysis of planetary entry, descent, and landing (EDL) for Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Titan. The purpose of SAPE is to provide a variable-fidelity capability for conceptual and preliminary analysis within the same framework. SAPE includes the following analysis modules: geometry, trajectory, aerodynamics, aerothermal, thermal protection system, and structural sizing. SAPE uses the Python language-a platform-independent open-source software for integration and for the user interface. The development has relied heavily on the object-oriented programming capabilities that are available in Python. Modules are provided to interface with commercial and government off-the-shelf software components (e.g., thermal protection systems and finite-element analysis). SAPE runs on Microsoft Windows and Apple Mac OS X and has been partially tested on Linux.

  12. The 2010 Saturn's Great White Spot: Observations and models

    Science.gov (United States)

    Sanchez-Lavega, A.

    2011-12-01

    On December 5, 2010, a major storm erupted in Saturn's northern hemisphere at a planetographic latitude of 37.7 deg [1]. These phenomena are known as "Great White Spots" (GWS) and they have been observed once per Saturn year since the first case confidently reported in 1876. The last event occurred at Saturn's Equator in 1990 [2]. A GWS differs from similar smaller-scale storms in that it generates a planetary-scale disturbance that spreads zonally spanning the whole latitude band. We report on the evolution and motions of the 2010 GWS and its associated disturbance during the months following the outbreak, based mainly on high quality images obtained in the visual range submitted to the International Outer Planet Watch PVOL database [3], with the 1m telescope at Pic-du-Midi Observatory and the 2.2 m telescope at Calar Alto Observatory. The GWS "head source" extinguished by June 2011 implying that it survived about 6 months. Since this source is assumed to be produced by water moist convection, a reservoir of water vapor must exist at a depth of 10 bar and at the same time a disturbance producing the necessary convergence to trigger the ascending motions. The high temporal sampling and coverage allowed us to study the dynamics of the GWS in detail and the multi-wavelength observations provide information on its cloud top structure. We present non-linear simulations using the EPIC code of the evolution of the potential vorticity generated by a continuous Gaussian heat source extending from 10 bar to about 1 bar, that compare extraordinary well to the observed cloud field evolution. Acknowledgements: This work has been funded by Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464-07. The presentation is done on behalf of the team listed in Reference [1]. [1]Sánchez-Lavega A., et al., Nature, 475, 71-74 (2011) [2]Sánchez-Lavega A., et al., Nature, 353, 397-401 (1991) [3]Hueso R., et al., Planet. Space Sci., 58, 1152-1159 (2010).

  13. Heat-shield for Extreme Entry Environment Technology (HEEET) Development Status

    Science.gov (United States)

    Venkatapathy, Ethiraj; Ellerby, Don; Gage, Peter

    2016-01-01

    The Heat shield for Extreme Entry Environment Technology (HEEET) Project is a NASA STMD and SMD co-funded effort. The goal is to develop and mission infuse a new ablative Thermal Protection System that can withstand extreme entry. It is targeted to support NASA's high priority missions, as defined in the latest decadal survey, to destinations such as Venus and Saturn in-situ robotic science missions. Entry into these planetary atmospheres results in extreme heating. The entry peak heat-flux and associated pressure are estimated to be between one and two orders of magnitude higher than those experienced by Mars Science Laboratory or Lunar return missions. In the recent New Frontiers community announcement NASA has indicated that it is considering providing an increase to the PI managed mission cost (PIMMC) for investigations utilizing the Heat Shield for Extreme Entry Environment Technology (HEEET) and in addition, NASA is considering limiting the risk assessment to only their accommodation on the spacecraft and the mission environment. The HEEET ablative TPS utilizes 3D weaving technology to manufacture a dual layer material architecture. The 3-D weaving allows for flat panels to be woven. The dual layer consists of a top layer designed to withstand the extreme external environment while the inner or insulating layer by design, is designed to achieve low thermal conductivity, and it keeps the heat from conducting towards the structure underneath. Both arc jet testing combined with material properties have been used to develop thermal response models that allows for comparison of performance with heritage carbon phenolic. A 50% mass efficiency is achieved by the dual layer construct compared to carbon phenolic for a broad range of missions both to Saturn and Venus. The 3-D woven flat preforms are molded to achieve the shape as they are compliant and then resin infusion with curing forms a rigid panels. These panels are then bonded on to the aeroshell structure. Gaps

  14. Hydrodynamic ultrasonic probe

    Science.gov (United States)

    Day, Robert A.; Conti, Armond E.

    1980-01-01

    An improved probe for in-service ultrasonic inspection of long lengths of a workpiece, such as small diameter tubing from the interior. The improved probe utilizes a conventional transducer or transducers configured to inspect the tubing for flaws and/or wall thickness variations. The probe utilizes a hydraulic technique, in place of the conventional mechanical guides or bushings, which allows the probe to move rectilinearly or rotationally while preventing cocking thereof in the tube and provides damping vibration of the probe. The probe thus has lower friction and higher inspection speed than presently known probes.

  15. Predicting the Diversity of Foreign Entry Modes

    DEFF Research Database (Denmark)

    Hashai, Niron; Geisler Asmussen, Christian; Benito, Gabriel

    2007-01-01

    This paper expands entry mode literature by referring to multiple modes exerted in different value chain activities within and across host markets, rather than to a single entry mode at the host market level. Scale of operations and knowledge intensity are argued to affect firms' entry mode...... diversity across value chain activities and host markets. Analyzing a sample of Israeli based firms we show that larger firms exhibit a higher degree of entry mode diversity both across value chain activities and across host markets. Higher levels of knowledge intensity are also associated with more...... diversity in firms' entry modes across both dimensions....

  16. Discovery of a Jupiter/Saturn Analog with Gravitational Microlensing

    Energy Technology Data Exchange (ETDEWEB)

    Gaudi, B; Bennett, D; Udalski, A; Gould, A; Christie, G; Maoz, D; Dong, S; McCormick, J; Szymanski, M; Tristram, P; Nikolaev, S; Paczynski, B; Kubiak, M; Pietrzynski, G; Soszynski, I; Szewczyk, O; Ulaczyk, K; Wyrzykowski, L; DePoy, D; Han, C; Kaspi, S; Lee, C; Mallia, F; Natusch, T; Pogge, R; Park, B; Abe, F; Bond, I; Botzler, C; Fukui, A; Hearnshaw, J; Itow, Y; Kamiya, K; Korpela, A; Kilmartin, P; Lin, W; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okumura, T; Ohnishi, K; Rattenbury, N; Sako, T; Saito, T; Sato, S; Skuljan, L; Sullivan, D; Sumi, T; Sweatman, W; Yock, P; Albrow, M; Beaulieu, J; Burgdorf, M; Cook, K; Coutures, C; Dominik, M; Dieters, S; Fouque, P; Greenhill, J; Horne, K; Steele, I; Tsapras, Y; Chaboyer, B; Crocker, A; Frank, S; Macintosh, B

    2007-11-08

    Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the first detection of a multiple-planet system with microlensing. We identify two planets with masses of {approx} 0.71 and {approx} 0.27 times the mass of Jupiter and orbital separations of {approx} 2.3 and {approx} 4.6 astronomical units orbiting a primary of mass {approx} 0.50 solar masses. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only 6 confirmed microlensing planet detections suggests that solar system analogs may be common.

  17. On the generation of plasma waves in Saturn's inner magnetosphere

    Science.gov (United States)

    Barbosa, D. D.; Kurth, W. S.

    1993-01-01

    Voyager 1 plasma wave measurements of Saturn's inner magnetosphere are reviewed with regard to interpretative aspects of the wave spectrum. A comparison of the wave emission profile with the electron plasma frequency obtained from in situ measurements of the thermal ion density shows good agreement with various features in the wave data identified as electrostatic modes and electromagnetic radio waves. Theoretical calculations of the critical flux of superthermal electrons able to generate whistler-mode waves and electrostatic electron cyclotron harmonic waves through a loss-cone instability are presented. The comparison of model results with electron measurements shows excellent agreement, thereby lending support to the conclusion that a moderate perpendicular anisotropy in the hot electron distribution is present in the equatorial region of L = 5-8.

  18. Attitude control of Mariner Jupiter-Saturn spacecraft

    Science.gov (United States)

    Bahrami, K. A.

    1976-01-01

    A major challenge of the Mariner Jupiter-Saturn '77 spacecraft was devising a suboptimal attitude controller that could meet the demanding mission requirements. The challenge was met by implementing a discrete stochastic controller for a specially designed onboard computer. The paper describes the design and operation of the controller, based on a simple model of spacecraft dynamics. Two types of cruising modes are considered: inertial cruise, where spacecraft attitude is determined from gyro position outputs, and celestial cruise, where position information is obtained from sun sensors and a star tracker. These two cruise modes under conditions of disturbances were simulated on computer, and the results showed that the controller maintained the spacecraft attitude with low rates. An appendix gives details on the single-step predictor.

  19. Analysis of Electric Propulsion System for Exploration of Saturn

    Directory of Open Access Journals (Sweden)

    Carlos Renato Huaura Solórzano

    2009-01-01

    Full Text Available Exploration of the outer planets has experienced new interest with the launch of the Cassini and the New Horizons Missions. At the present time, new technologies are under study for the better use of electric propulsion system in deep space missions. In the present paper, the method of the transporting trajectory is used to study this problem. This approximated method for the flight optimization with power-limited low thrust is based on the linearization of the motion of a spacecraft near a keplerian orbit that is close to the transfer trajectory. With the goal of maximizing the mass to be delivered in Saturn, several transfers were studied using nuclear, radioisotopic and solar electric propulsion systems.

  20. The influence of Titan on Saturn kilometric radiation

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2010-02-01

    Full Text Available Previous studies have shown that the occurrence probability of Saturn Kilometric Radiation (SKR appears to be influenced by the local time of Titan. Using a more extensive set of data than the original study, we confirm the correlation of higher occurrence probability of SKR when Titan is located near local midnight. In addition, the direction finding capability of the Cassini Radio Plasma Wave instrument (RPWS is used to determine if this radio emission emanates from particular source regions. We find that most source regions of SKR are located in the mid-morning sector of local time even when Titan is located near midnight. However, some emission does appear to have a source in the Saturnian nightside, consistent with electron precipitation from field lines that have recently mapped to near Titan.

  1. Detection of Water Ice on Saturn's Satellite Phoebe

    Science.gov (United States)

    Owen, T. C.; Cruikshank, D. P.; DalleOre, C. M.; Geballe, T. R.; Roush, T. L.; deBergh, C.

    1999-01-01

    The near-infrared reflectance spectrum of Saturn's satellite Phoebe shows a broad absorption band at 2.0 micrometers and absorption at lambda > 2.2 micrometers, both characteristic of H2O ice. We have successfully modeled the surface of Phoebe with an intimate (granular) mix of H2O ice (3% by weight, grain size 500 micrometers) mixed with fine grains of H2O ice (0.25%) with amorphous carbon (grain size 900 micrometers) as the dominant component. This model reproduces the shape of the measured spectrum and the observed albedo of 0.10 for Phoebe, but it is not unique. The presence of ice establishes Phoebe as an original member of the outer Solar System rather than a renegade asteroid.

  2. Trace Species Identified in Saturn's Northern Storm Region

    Science.gov (United States)

    Bjoraker, Gordon L.; Hesman, B. E.; Achterberg, R. K.

    2011-01-01

    The massive storm at 40degN on Saturn that began in December 2010 has produced significant and lasting effects in the northern hemisphere on temperature and species abundances [I}. The northern storm region was observed at 0.5/cm spectral resolution in March 2011 by Cassini's Composite Infrared Spectrometer (CIRS). Temperatures in the stratosphere as high as 190 K were derived from CIRS spectra in warm regions referred to as "beacons". Other longitudes exhibit cold temperatures in the upper troposphere. These unusual conditions allow us to identify rare species such as C4H2, C3H4, and CO2 in the stratosphere, as well as to measure changes in the abundance of phosphine (PH3) in the troposphere. Phosphine is a disequilibrium species whose abundance is a tracer of upwelling from the deep atmosphere.

  3. Experimental results and modeling of a dynamic hohlraum on SATURN

    Energy Technology Data Exchange (ETDEWEB)

    Derzon, M.S.; Allshouse, G.O.; Deeney, C.; Leeper, R.J.; Nash, T.J. [Sandia National Labs., Albuquerque, NM (United States); Matuska, W.; Peterson, D.L. [Los Alamos National Lab., NM (United States); MacFarlane, J.J. [Univ. of Wisconsin, Madison, WI (United States); Ryutov, D.D. [Lawrence Livermore National Lab., CA (United States)

    1998-06-01

    Experiments were performed at SATURN, a high current z-pinch, to explore the feasibility of creating a hohlraum by imploding a tungsten wire array onto a low-density foam. Emission measurements in the 200--280 eV energy band were consistent with a 110--135 eV Planckian before the target shock heated, or stagnated, on-axis. Peak pinch radiation temperatures of nominally 160 eV were obtained. Measured early time x-ray emission histories and temperature estimates agree well with modeled performance in the 200--280 eV band using a 2D radiation magneto-hydrodynamics code. However, significant differences are observed in comparisons of the x-ray images and 2D simulations.

  4. How the Enceladus Dust Jets Form Saturn's E Ring

    Science.gov (United States)

    Kempf, S.; Uwe, B.; Schmidt, J.; Postberg, F.; Srama, R.

    2009-05-01

    Pre--Cassini models of Saturn's E ring failed to reproduce its peculiar vertical structure inferred from earth-bound observations. After the discovery of an active ice- volcanism of Saturn's icy moon Enceladus the relevance of the directed injection of particles for the vertical ring structure of the E ring was swiftly recognised. However, simple models for the delivery of particles from the plume to the ring predict a too small vertical ring thickness and overestimate the amount of the injected dust. Here we report on numerical simulations of grains leaving the plume and populating the dust torus of Enceladus. We run a large number of dynamical simulations including gravity and Lorentz force to investigate the earliest phase of the ring particle life span. The evolution of the electrostatic charge carried by the initially uncharged grains is treated selfconsistently. Freshly ejected plume particles are moving in almost circular orbits because the Enceladus orbital speed exceeds the particles' ejection speeds by far. Only a small fraction of grains that leave the Hill sphere of Enceladus survive the next encounter with the moon. The flux and the size distribution of the surviving grains, replenishing the ring particle reservoir, differs significantly from the flux and the size distribution of the ejected plume particles. Our numerical simulations reproduce the vertical ring profile measured by the Cassini dust instrument CDA. From our simulations we calculate the deposition rates of plume particles hitting Enceladus' surface. We find that at a distance of 100 m from a jet a 10 m sized ice boulder should be covered by plume particles in 105 to 106 years.

  5. Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

    Science.gov (United States)

    Sittler, E.; Cooper, J.; Hartle, R.; Simpson, D.; Johnson, R.; Thomsen, M.; Arridge, C.

    2011-01-01

    We present the present status of an investigation of the rotation rate of Saturn's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. for SOI and similar to that used by Thomsen et al.. This technique allows one to nearly cover the full energy range of the Cassini Plasma Spectrometer (CAPS) IMS from 1 V . E/Q frame, it does work during roll maneuvers. We make comparisons with the bi-Maxwellian fitting technique developed by Wilson et al. and the similar velocity moment technique by Thomsen et al. . We concentrate our analysis when ion composition data is available, which is used to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The chosen periods have high enough telemetry rates (4 kbps or higher) so that coincidence ion data, similar to that used by Sittler et al. for SOI is available. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. In the future we will then make comparisons with magnetic field observations, Saturn ionosphere conductivities as presently known and the field aligned currents necessary for the planet to enforce corotation of the rotating plasma.

  6. Saturn's Atmospheric Composition from Observations by the Cassini/Composite Infrared Spectrometer

    Science.gov (United States)

    Abbas, M. M.; Young, M.; LeClair, A. C.; Achterberg, R. K.; Flasar, F. M.; Kunde, V. G.

    2010-01-01

    Thermal emission infrared observation of Saturn s atmosphere are being made by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft since its insertion in Saturn s orbit on July 2nd, 2004. The measurements made in both limb and nadir modes of observations consist of infrared spectra in the 10-1400/cm region with a variable spectral resolution of 0.53/cm and 2.8/cm, and exhibit rotational and vibrational spectral features that may be analyzed for retrieval of the thermal structure and constituent distribution of Saturn s atmosphere. In this paper, we present a comprehensive analysis of the CIRS infrared observed spectra for retrieval of Saturn s atmospheric composition focusing on the distributions of some selected hydrocarbons, phosphine, ammonia, and possible determination of the isotopic ratios of some species with sufficiently strong isolated spectral features. A comparison of the retrieved constituent distributions with the available data in the literature will be made.

  7. HST SATURN WFPC2 3 RING PLANE CROSSING V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains images of the Saturn system taken by the Wide Field/Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST) through November 1995....

  8. Cassini Attitude and Articulation Control Subsystem Fault Protection Challenges During Saturn Proximal Orbits

    Science.gov (United States)

    Bates, David M.

    2015-01-01

    NASA's Cassini Spacecraft, launched on October 15th, 1997 arrived at Saturn on June 30th, 2004, is the largest and most ambitious interplanetary spacecraft in history. As the first spacecraft to achieve orbit at Saturn, Cassini has collected science data throughout its four-year prime mission (2004-08), and has since been approved for a first and second extended mission through 2017. As part of the final extended mission, Cassini will begin an aggressive and exciting campaign of high inclination low altitude flybys within the inner most rings of Saturn, skimming Saturn's outer atmosphere, until the spacecraft is finally disposed of via planned impact with the planet. This final campaign, known as the proximal orbits, presents unique fault protection related challenges, the details of which are discussed in this paper.

  9. VOYAGER 1&2 SATURN BRIGHTNESS NORTH/SOUTH MAP SET V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains Voyager 1 and 2 measurements of the brightness of Saturn at H Lyman alpha and in the H2 Lyman and Werner bands shortward of H Lyman alpha....

  10. Artists drawing of partial cutaway view of Apollo/Saturn IB space vehicle

    Science.gov (United States)

    1968-01-01

    Artists drawing of a partial cutaway view of an Apollo/Saturn IB space vehicle in a launch configuration. Arrow point to various features and components of the vehicle. This drawing is representative of the Apollo 7 space vehicle.

  11. Tidal Response of Jupiter and Saturn from CMS calculationsTidal Response of Jupiter and Saturn from CMS calculations

    Science.gov (United States)

    Wahl, Sean; Hubbard, William B.; Militzer, Burkhard

    2016-10-01

    The Juno gravity science system promises to provide observational data from Jupiter's gravitational field at an unprecedented precision. Meanwhile, recent ab-initio simulations on mixtures of hydrogen and helium allow for the construction of realistic interior models. The concentric Maclaurin spheroid (CMS) numerical method has been developed for efficient, non-perturbative, self-consistent calculations of shape and gravitational field of a rotating liquid body to this desired precision. Here we present a generalization of the CMS method to three dimensions and included the effect of tides from a satellite. We have identified a number of unexpected features of the static tidal response in the case where a planet's shape is dominated by the rotational bulge. In the general case, there is state mixing of the spherical-harmonic components of the response to the corresponding components of the rotational and tidal excitations. This breaks the degeneracy of the tidal love numbers knm with m, and introduces a dependence of knm on the orbital distance of the satellite. Notably for Jupiter and Saturn, the predicted value of k2 is significantly higher when the planet's high rotation rates are taken into account: k2=0.413 for Saturn and k2=0.590 for Jupiter, accounting for an ~13% and 10% increase over the non-rotating case respectively. We have also done preliminary estimates for the off-resonance dynamic response, which may lead to an additional significant increase in k2. Accurate models of tidal response will be essential for interpreting gravity observations from Juno and future studies, particularly for when filtering for signals from interior dynamics in the observed field. This work was supported by NASA's Juno project. Sean Wahl and Burkhard Militzer acknowledge the support of the National Science Foundation (astronomy and astrophysics research grant 1412646).

  12. Pico Reentry Probes: Affordable Options for Reentry Measurements and Testing

    Science.gov (United States)

    Ailor, William H.; Kapoor, Vinod B.; Allen, Gay A., Jr.; Venkatapathy, Ethiraj; Arnold, James O.; Rasky, Daniel J.

    2005-01-01

    It is generally very costly to perform in-space and atmospheric entry experiments. This paper presents a new platform - the Pico Reentry Probe (PREP) - that we believe will make targeted flight-tests and planetary atmospheric probe science missions considerably more affordable. Small, lightweight, self-contained, it is designed as a "launch and forget" system, suitable for experiments that require no ongoing communication with the ground. It contains a data recorder, battery, transmitter, and user-customized instrumentation. Data recorded during reentry or space operations is returned at end-of-mission via transmission to Iridium satellites (in the case of earth-based operations) or a similar orbiting communication system for planetary missions. This paper discusses possible applications of this concept for Earth and Martian atmospheric entry science. Two well-known heritage aerodynamic shapes are considered as candidates for PREP: the shape developed for the Planetary Atmospheric Experiment Test (PAET) and that for the Deep Space II Mars Probe.

  13. Near-infrared spectra of Saturn's ring spokes from Cassini-VIMS data

    Science.gov (United States)

    D'Aversa, E.; Bellucci, G.; Filacchione, G.; Cerroni, P.; Nicholson, P. D.; Carrozzo, F. G.; Altieri, F.; Oliva, F.; Geminale, A.; Sindoni, G.; Hedman, M. M.

    2017-09-01

    The spokes appearing on the Saturn's rings every about 14 years are still not fully understood. They were observed for the first time in the infrared from VIMS spectrometer on board Cassini. We will discuss ongoing analyses of spokes' spectral data, highlighting the relevance of Saturn and rings as further illumination sources for spokes other than direct sunlight. Biases and possible consequences will be discussed.

  14. Quantitative measurements of Jupiter, Saturn, their rings and satellites made from Voyager imaging data

    Science.gov (United States)

    Collins, S. A.; Bunker, A. S.

    1983-01-01

    The Voyager spacecraft cameras use selenium-sulfur slow scan vidicons to convert focused optical images into sensible electrical signals. The vidicon-generated data thus obtained are the basis of measurements of much greater precision than was previously possible, in virtue of their superior linearity, geometric fidelity, and the use of in-flight calibration. Attention is given to positional, radiometric, and dynamical measurements conducted on the basis of vidicon data for the Saturn rings, the Saturn satellites, and the Jupiter atmosphere.

  15. Mobile Game Probes

    DEFF Research Database (Denmark)

    Borup Lynggaard, Aviaja

    2006-01-01

    This paper will examine how probes can be useful for game designers in the preliminary phases of a design process. The work is based upon a case study concerning pervasive mobile phone games where Mobile Game Probes have emerged from the project. The new probes are aimed towards a specific target...... group and the goal is to specify the probes so they will cover the most relevant areas for our project. The Mobile Game Probes generated many interesting results and new issues occurred, since the probes came to be dynamic and favorable for the process in new ways....

  16. Titan Atmospheric Entry Radiative Heating

    Science.gov (United States)

    Brandis, Aaron; Cruden, Brett

    2017-01-01

    Detailed spectrally and spatially resolved radiance has been measured in the Electric Arc Shock Tube for conditions relevant to Titan entry, varying atmospheric composition, free-stream density (equivalent to altitude) and shock velocity. Permutations in atmospheric composition include 1.1, 2, 5 and 8.6 CH4 by mole with a balance of N2 and 1.5 CH4 0.5 Ar 98 N2 by mole, which is consistent with the current understanding of Titan's atmosphere. The effect of gas impurities identified in previous shock tube studies were also examined by testing in pure N2 and deliberate addition of air to the CH4N2 mixtures. The test campaign measured radiation at velocities from 4.7 kms to 8 kms and free-stream pressures from 0.1 to 0.47 Torr. These conditions cover a range of potential trajectories for flight missions, including a direct ballistic trajectory, a fly by or an extremely high speed entry. Radiances measured in this work are substantially larger compared to that reported both in past EAST test campaigns and other shock tube facilities. Depending on the metric used for comparison, the discrepancy can be as high as an order of magnitude. Potential causes for the discrepancy, such as the effect of oxygen due to Air leakage, gas composition and purity are discussed. The present work provides a new benchmark set of data to replace those published in previous studies.

  17. Galileo Space Probe News Conference. Part 1

    Science.gov (United States)

    1996-01-01

    This NASA Kennedy Space Center (KSC) video release presents Part 1 of a press conference regarding the successful entry of the Galileo Space Probe into Jupiter's atmosphere. The press conference panel is comprised of twelve principal investigators and project scientists that oversee the Galileo mission. Among these panelists, William J. O'Neil (Jet Propulsion Lab.) begins the video praising all of the scientists that worked on the orbiter mission. He then presents a visual overview of Galileo's overall mission trajectory and schedule. Marcie Smith (NASA Ames Research Center) then describes the Galileo Probe mission and the overall engineering and data acquisition aspects of the Probe's Jupiter atmospheric entry. Dr. Richard Young (NASA Ames Research Center) follows with a brief scientific overview, describing the measurements of the atmospheric composition as well as the instruments that were used to gather the data. Atmospheric pressure, temperature, density, and radiation levels of Jupiter were among the most important parameters measured. It is explained that these measurements would be helpful in determining among other things, the overall dynamic meteorology of Jupiter. A question and answer period follows the individual presentations. Atmospheric thermal structure, water abundances, wind profiles, radiation, cloud structure, chemical composition, and electricity are among the topics discussed. Parts 2 and 3 of the press conference can be found in document numbers NONP-NASA-VT-2000001074, and NONP-NASA-VT-2000001075.

  18. Cusp observation at Saturn's high-latitude magnetosphere by the Cassini spacecraft

    Science.gov (United States)

    Jasinski, J M; Arridge, C S; Lamy, L; Leisner, J S; Thomsen, M F; Mitchell, D G; Coates, A J; Radioti, A; Jones, G H; Roussos, E; Krupp, N; Grodent, D; Dougherty, M K; Waite, J H

    2014-01-01

    We report on the first analysis of magnetospheric cusp observations at Saturn by multiple in situ instruments onboard the Cassini spacecraft. Using this we infer the process of reconnection was occurring at Saturn's magnetopause. This agrees with remote observations that showed the associated auroral signatures of reconnection. Cassini crossed the northern cusp around noon local time along a poleward trajectory. The spacecraft observed ion energy-latitude dispersions—a characteristic signature of the terrestrial cusp. This ion dispersion is “stepped,” which shows that the reconnection is pulsed. The ion energy-pitch angle dispersions suggest that the field-aligned distance from the cusp to the reconnection site varies between ∼27 and 51 RS. An intensification of lower frequencies of the Saturn kilometric radiation emissions suggests the prior arrival of a solar wind shock front, compressing the magnetosphere and providing more favorable conditions for magnetopause reconnection. Key Points We observe evidence for reconnection in the cusp plasma at Saturn We present evidence that the reconnection process can be pulsed at Saturn Saturn's cusp shows similar characteristics to the terrestrial cusp PMID:25821276

  19. Cusp observation at Saturn's high-latitude magnetosphere by the Cassini spacecraft.

    Science.gov (United States)

    Jasinski, J M; Arridge, C S; Lamy, L; Leisner, J S; Thomsen, M F; Mitchell, D G; Coates, A J; Radioti, A; Jones, G H; Roussos, E; Krupp, N; Grodent, D; Dougherty, M K; Waite, J H

    2014-03-16

    We report on the first analysis of magnetospheric cusp observations at Saturn by multiple in situ instruments onboard the Cassini spacecraft. Using this we infer the process of reconnection was occurring at Saturn's magnetopause. This agrees with remote observations that showed the associated auroral signatures of reconnection. Cassini crossed the northern cusp around noon local time along a poleward trajectory. The spacecraft observed ion energy-latitude dispersions-a characteristic signature of the terrestrial cusp. This ion dispersion is "stepped," which shows that the reconnection is pulsed. The ion energy-pitch angle dispersions suggest that the field-aligned distance from the cusp to the reconnection site varies between ∼27 and 51 R S . An intensification of lower frequencies of the Saturn kilometric radiation emissions suggests the prior arrival of a solar wind shock front, compressing the magnetosphere and providing more favorable conditions for magnetopause reconnection. We observe evidence for reconnection in the cusp plasma at SaturnWe present evidence that the reconnection process can be pulsed at SaturnSaturn's cusp shows similar characteristics to the terrestrial cusp.

  20. Extended Bright Bodies - Flight and Ground Software Challenges on the Cassini Mission at Saturn

    Science.gov (United States)

    Sung, Tina S.; Burk, Thomas A.

    2016-01-01

    Extended bright bodies in the Saturn environment such as Saturn's rings, the planet itself, and Saturn's satellites near the Cassini spacecraft may interfere with the star tracker's ability to find stars. These interferences can create faulty spacecraft attitude knowledge, which would decrease the pointing accuracy or even trip a fault protection response on board the spacecraft. The effects of the extended bright body interference were observed in December of 2000 when Cassini flew by Jupiter. Based on this flight experience and expected star tracker behavior at Saturn, the Cassini AACS operations team defined flight rules to suspend the star tracker during predicted interference windows. The flight rules are also implemented in the existing ground software called Kinematic Predictor Tool to create star identification suspend commands to be uplinked to the spacecraft for future predicted interferences. This paper discusses the details of how extended bright bodies impact Cassini's acquisition of attitude knowledge, how the observed data helped the ground engineers in developing flight rules, and how automated methods are used in the flight and ground software to ensure the spacecraft is continuously operated within these flight rules. This paper also discusses how these established procedures will continue to be used to overcome new bright body challenges that Cassini will encounter during its dips inside the rings of Saturn for its final orbits of a remarkable 20-year mission at Saturn.

  1. Parametric Thermal Soak Model for Earth Entry Vehicles

    Science.gov (United States)

    Agrawal, Parul; Samareh, Jamshid; Doan, Quy D.

    2013-01-01

    The analysis and design of an Earth Entry Vehicle (EEV) is multidisciplinary in nature, requiring the application many disciplines. An integrated tool called Multi Mission System Analysis for Planetary Entry Descent and Landing or M-SAPE is being developed as part of Entry Vehicle Technology project under In-Space Technology program. Integration of a multidisciplinary problem is a challenging task. Automation of the execution process and data transfer among disciplines can be accomplished to provide significant benefits. Thermal soak analysis and temperature predictions of various interior components of entry vehicle, including the impact foam and payload container are part of the solution that M-SAPE will offer to spacecraft designers. The present paper focuses on the thermal soak analysis of an entry vehicle design based on the Mars Sample Return entry vehicle geometry and discusses a technical approach to develop parametric models for thermal soak analysis that will be integrated into M-SAPE. One of the main objectives is to be able to identify the important parameters and to develop correlation coefficients so that, for a given trajectory, can estimate the peak payload temperature based on relevant trajectory parameters and vehicle geometry. The models are being developed for two primary thermal protection (TPS) materials: 1) carbon phenolic that was used for Galileo and Pioneer Venus probes and, 2) Phenolic Impregnated Carbon Ablator (PICA), TPS material for Mars Science Lab mission. Several representative trajectories were selected from a very large trade space to include in the thermal analysis in order to develop an effective parametric thermal soak model. The selected trajectories covered a wide range of heatload and heatflux combinations. Non-linear, fully transient, thermal finite element simulations were performed for the selected trajectories to generate the temperature histories at the interior of the vehicle. Figure 1 shows the finite element model

  2. Titan Lifting Entry & Atmospheric Flight (T-LEAF) Science Mission

    Science.gov (United States)

    Lee, G.; Sen, B.; Ross, F.; Sokol, D.

    2016-12-01

    Northrop Grumman has been developing the Titan Lifting Entry & Atmospheric Flight (T-LEAF) sky rover to roam the lower atmosphere and observe at close quarters the lakes and plains of Saturn's ocean moon, Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in-situ instruments to the surface of Titan. T-LEAF is a highly maneuverable sky rover and its aerodynamic shape (i.e., a flying wing) does not restrict it to following prevailing wind patterns on Titan, but allows mission operators to chart its course. This freedom of mobility allows T-LEAF to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations. We will present a straw man concept of T-LEAF, including size, mass, power, on-board science payloads and measurement, and surface science dropsonde deployment CONOPS. We will discuss the various science instruments and their vehicle level impacts, such as meteorological and electric field sensors, acoustic sensors for measuring shallow depths, multi-spectral imagers, high definition cameras and surface science dropsondes. The stability of T-LEAF and its long residence time on Titan will provide for time to perform a large aerial survey of select prime surface targets deployment of dropsondes at selected locations surface measurements that are coordinated with on-board remote measurements communication relay capabilities to orbiter (or Earth). In this context, we will specifically focus upon key factors impacting the design and performance of T-LEAF science: science payload accommodation, constraints and opportunities characteristics of flight, payload deployment and measurement CONOPS in the Titan atmosphere. This presentation will show how these factors provide constraints as well as enable opportunities for novel long duration scientific studies of Titan's surface.

  3. Preventing re-entry to foster care.

    Science.gov (United States)

    Carnochan, Sarah; Rizik-Baer, Daniel; Austin, Michael J

    2013-01-01

    Re-entry to foster care generally refers to circumstances in which children who have been discharged from foster care to be reunified with their family of origin, adopted, or provided kinship guardianship are returned to foster care. In the context of the federal performance measurement system, re-entry refers specifically to a return to foster care following an unsuccessful reunification. The federal Children and Family Services Review measures re-entry to foster care with a single indicator, called the permanency of reunification indicator, one of four indicators comprising the reunification composite measure. This review focuses on research related to the re-entry indicator, including the characteristics of children, caregivers and families, as well as case and child welfare services that are associated with a higher or lower risk of re-entry to foster care. Promising post-reunification services designed to prevent re-entry to foster care are described.

  4. Risk Assessment for Destructive Re-Entry

    Science.gov (United States)

    Lips, T.; Koppenwallner, G.; Bianchi, L.; Klinkrad, H.

    2009-03-01

    From 2007 to 2008, Hypersonic Technology Göttingen (HTG) worked on a study called Risk Assessment for Destructive Re-entry (RADR). The main purposes of this study were to identify and to quantify the inherent uncertainties of re-entry analysis tools, and to provide possible risk mitigation measures. For these purposes, three basic risk scenarios were specified: a 1-ton-class satellite without propulsion for uncontrolled re-entry, a 6-ton-class satellite with propulsion and the capability to perform a controlled re-entry, and a 1-ton-class launcher upper stage re-entering uncontrolled. Based on the identified uncertainty parameters, variation analyses were conducted for these scenarios with the two ESA tools for re-entry analysis SCARAB (Spacecraft Atmospheric Reentry and Aerothermal Breakup) and SESAM (Spacecraft Entry Survival Analysis Module). This paper describes the major results of the RADR study.

  5. Entry menus in bilingual electronic dictionaries

    OpenAIRE

    Lew, Robert; Tokarek, Patryk

    2010-01-01

    The study undertakes to assess the efficiency of entry menus in bilingual dictionaries in the electronic format. An experimental dictionary interface is tested for performance in terms of access speed and task success. The task underlying dictionary use is guided Polish-to-English translation, performed under three conditions by 90 Polish learners of English. The first version of the dictionary displays a complete polysemous entry immediately after an entry is selected. In the second version ...

  6. Deciphering the embedded wave in Saturn's Maxwell ringlet

    Science.gov (United States)

    French, Richard G.; Nicholson, Philip D.; Hedman, Mathew M.; Hahn, Joseph M.; McGhee-French, Colleen A.; Colwell, Joshua E.; Marouf, Essam A.; Rappaport, Nicole J.

    2016-11-01

    The eccentric Maxwell ringlet in Saturn's C ring is home to a prominent wavelike structure that varies strongly and systematically with true anomaly, as revealed by nearly a decade of high-SNR Cassini occultation observations. Using a simple linear "accordion" model to compensate for the compression and expansion of the ringlet and the wave, we derive a mean optical depth profile for the ringlet and a set of rescaled, background-subtracted radial wave profiles. We use wavelet analysis to identify the wave as a 2-armed trailing spiral, consistent with a density wave driven by an m = 2 outer Lindblad resonance (OLR), with a pattern speed Ωp = 1769.17° d-1 and a corresponding resonance radius ares = 87530.0 km. Estimates of the surface mass density of the Maxwell ringlet range from a mean value of 11g cm-2 derived from the self-gravity model to 5 - 12gcm-2 , as inferred from the wave's phase profile and a theoretical dispersion relation. The corresponding opacity is about 0.12 cm2 g-1, comparable to several plateaus in the outer C ring (Hedman, M.N., Nicholson, P.D. [2014]. Mont. Not. Roy. Astron. Soc. 444, 1369-1388). A linear density wave model using the derived wave phase profile nicely matches the wave's amplitude, wavelength, and phase in most of our observations, confirming the accuracy of the pattern speed and demonstrating the wave's coherence over a period of 8 years. However, the linear model fails to reproduce the narrow, spike-like structures that are prominent in the observed optical depth profiles. Using a symplectic N-body streamline-based dynamical code (Hahn, J.M., Spitale, J.N. [2013]. Astrophys. J. 772, 122), we simulate analogs of the Maxwell ringlet, modeled as an eccentric ringlet with an embedded wave driven by a fictitious satellite with an OLR located within the ring. The simulations reproduce many of the features of the actual observations, including strongly asymmetric peaks and troughs in the inward-propagating density wave. We argue that

  7. Innate immunity modulation in virus entry.

    Science.gov (United States)

    Faure, Mathias; Rabourdin-Combe, Chantal

    2011-07-01

    Entry into a cell submits viruses to detection by pattern recognition receptors (PRRs) leading to an early innate anti-viral response. Several viruses evolved strategies to avoid or subvert PRR recognition at the step of virus entry to promote infection. Whereas viruses mostly escape from soluble PRR detection, endocytic/phagocytic PRRs, such as the mannose receptor or DC-SIGN, are commonly used for virus entry. Moreover, virion-incorporated proteins may also offer viruses a way to dampen anti-viral innate immunity upon virus entry, and entering viruses might usurp autophagy to improve their own infectivity. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Parallel Probe Readout

    NARCIS (Netherlands)

    Koelmans, W.W.

    2011-01-01

    In this thesis techniques are developed to read out nanoscale probes and arrays of probes.The main targeted application area is probe-based data storage.The work also contributes to other areas, such as metrology, biological sensing, materials research and nano-electro-mechanical switches. First, an

  9. Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

    Science.gov (United States)

    Sittler, E.; Cooper, J.; Simpson, D.; Paterson, W.

    2012-01-01

    We present the present status of an investigation of the rotation rate of Saturn 's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. (2005) [1] for SOI and similar to that used by Thomsen et al. (2010). This technique allows one to nearly cover the full energy range of the CAPS IMS from 1 V less than or equal to E/Q less than 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll manoeuvres. We have made comparisons with Wilson et al. (2008) [2] (2005-358 and 2005-284) who performs a bi-Maxwellian fit to the ion singles data and our results are nearly identical. We will also make comparisons with results by Thomsen et al. (2010) [3]. Our analysis uses ion composition data to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. Since our analysis is a velocity moments technique it will work within the inner magnetosphere where pickup ions are important and velocity distributions are non-Maxwellian. So, we will present results inside Enceladus' L shell and determine if mass loading is important. In the future we plan to make comparisons with magnetic field observations, use Saturn ionosphere conductivities as

  10. Compositional Evolution of Saturn's Rings Due to Meteoroid Bombardment

    Science.gov (United States)

    Cuzzi, J.; Estrada, P.; Young, Richard E. (Technical Monitor)

    1997-01-01

    In this paper we address the question of compositional evolution in planetary ring systems subsequent to meteoroid bombardment. The huge surface area to mass ratio of planetary rings ensures that this is an important process, even with current uncertainties on the meteoroid flux. We develop a new model which includes both direct deposition of extrinsic meteoritic "pollutants", and ballistic transport of the increasingly polluted ring material as impact ejecta. Our study includes detailed radiative transfer modeling of ring particle spectral reflectivities based on refractive indices of realistic constituents. Voyager data have shown that the lower optical depth regions in Saturn's rings (the C ring and Cassini Division) have darker and less red particles than the optically thicken A and B rings. These coupled structural-compositional groupings have never been explained; we present and explore the hypothesis that global scale color and compositional differences in the main rings of Saturn arise naturally from extrinsic meteoroid bombardment of a ring system which was initially composed primarily, but not entirely, of water ice. We find that the regional color and albedo differences can be understood if all ring material was initially identical (primarily water ice, based on other data, but colored by tiny amounts of intrinsic reddish, plausibly organic, absorber) and then evolved entirely by addition and mixing of extrinsic, nearly neutrally colored. plausibly carbonaceous material. We further demonstrate that the detailed radial profile of color across the abrupt B ring - C ring boundary can.constrain key unknown parameters in the model. Using new alternates of parameter values, we estimate the duration of the exposure to extrinsic meteoroid flux of this part of the rings, at least, to be on the order of 10(exp 8) years. This conclusion is easily extended by inference to the Cassini Division and its surroundings as well. This geologically young "age" is compatible

  11. South Polar Ammonia Clouds on Saturn°

    Science.gov (United States)

    Sromovsky, Lawrence A.; Baines, Kevin H.; Fry, Patrick M.

    2017-10-01

    Most of Saturn is covered by a thick cloud layer of unknown composition. Evidence of the underlying NH3 ice cloud (its strong 3-μm absorption signature) had so far been seen only in association with lightning storms, including the Great Storm of 2010-2011 (Sromovsky et al. 2013, Icarus 226, 402-418), near 35° N planetocentric latitude, and much smaller storms located near 36° S in the Storm Alley region (Baines et al. 2009, Planet. & Space Sci. 57, 1650-1658). In the Great Storm, NH3 ice reached the visible cloud tops. The Storm Alley clouds have more subtle 3-μm signatures, which is consistent with ammonia ice reaching into but not fully penetrating the upper cloud (Sromovsky et al. 2017, Icarus submitted). The presence of 3-μm absorption features in the south polar region is surprising because there is no associated lighting that would indicate deep convection. Radiation transfer modeling of October 2006 VIMS spectra of these features yields good fits with a stacked structure of a thin stratospheric haze, a physically thin and optically thin (~0.2 optical depths at 2 μm) layer of non-absorbing particles, a moderate layer of NH3 ice particles (r=2 μm, ~2 optical depths) near 550 mbar, then a clear region down to about 2 bars, which marks the top of a very optically thick layer of NH4SH particles, which provides a needed strong reduction in thermal emission in the 5-μm window. The structure of neighboring clouds differs dramatically in the NH4SH layer, which has a much lower optical depth and has a cloud top 1 bar deeper. But the ammonia layer is the main modulator of pseudo continuum I/F in reflected sunlight. That layer has an optical depth of about 1.3 in background clouds, but almost double that in the brightest clouds. What makes the 3-μm absorption of the NH3 ice layer more apparent in these polar clouds is the reduced optical depth of the upper cloud layer, which is an order of magnitude less than in other regions on Saturn, perhaps because of polar

  12. Sources of Mass and Energy Observed in Saturn's Rings

    Science.gov (United States)

    Riofrio, L. M.

    2005-12-01

    EVIDENCE from the laboratory of Saturn's Rings solves riddles of planet formation. Observations by Cassini and other spacecraft show conditions similiar to the birth of our Solar System. These observations lead to new theories of small-body accretion. Applications have benefits for physics and energy on Earth. There have been several open questions regarding the planets. Most puzzling is the formation of mountain-sized planetesimals from protostellar dust, for these objects could not form naturally. Power source of the "dynamo" generating planetary magnetic fields was also unknown. Internal heat generated by planets and even small moons is an additional mystery. These riddles may be explained by presence of primordial singularities in the Solar System's formation. Saturn's Rings are a field of ice in which the tracks of these objects may be seen. The Cassini spacecraft has returned many fascinating images of the Rings. We now know them to be home to massive unseen objects. Satellite objects glimpsed in the Encke and Keeler gaps show behaviour unlike moons of rock or ice. Discrete trails of dirt and molecular oxygen indicate radiation discharge emanating from these objects. Similiar trails photographed in Cassini's Division indicate massive objects where no large object has been sighted visually. We must consider whether the Rings could be a home to singularities. It is generally agreed the primordial singularities were created shortly after the Big Bang, and exist in unknown numbers today. Presence of these objects in the Solar System's formation would have seeded formation of planetesimals and larger bodies. Their hidden presence would explain both planetary magnetic fields and internal heat sources. They would also explain the Ring's presence and longetivity. The most convincing evidence for singularities would be radiation discharge. Observation of a polar "hot spot" on Enceladus can not be explained by old theories of radioactive decay. The only feasible source

  13. Saturn's satellites temperatures inferred from Cassini-VIMS reflectance spectra

    Science.gov (United States)

    Filacchione, G.; Capaccioni, F.; Clark, R. N.; Ciarniello, M.; Brown, R. H.; Cruikshank, D. P.; Buratti, B. J.; Cuzzi, J. N.; Spilker, L. J.; Nicholson, P. D.; Dalle Ore, C.; Cerroni, P.; Tosi, F.; Scipioni, F.

    2013-12-01

    The spectral position of the 3.6 μm continuum peak measured on Cassini-VIMS reflectance spectra is used as a marker to infer the temperature of the regolith particles covering the surfaces of Saturn's icy satellites. Laboratory measurements indicate that for pure water ice the position of the 3.6 μm peak is temperature-dependent: it shifts towards shorter wavelengths when the ice is cooled, moving from about 3.65 μm at T=123 K to about 3.55 μm at T=88 K. Starting from this experimental evidence we have used a 4th-degree polynomial fit between 3.2 and 3.8 µm to measure the wavelength at which the peak occurs with the view toward using it as a marker to retrieve the temperatures of the satellites. This method is applied to about 240 disk-integrated observations of Saturn's regular satellites collected by VIMS between 2004 and 2011 (Filacchione et al. Icarus 220, 2012) with solar phase in the 20-40 deg range, corresponding to late morning-early afternoon local times. From these observations we have retrieved average temperatures for Mimas (~88 K), Enceladus (trailing (~138K) and Iapetus leading hemisphere (>170K). For some satellites, like Tethys and Dione, for which observations on both leading and trailing hemispheres are available, we have measured average temperatures higher by about 10 K on the trailing than on the leading hemisphere. Temperatures measured by VIMS with this method are in general much higher than corresponding ones reported by CIRS: this is a consequence of the shallow skindepth (few microns) to which VIMS is sensitive while CIRS measures temperature at greater depth (few millimeters). Grain size and contaminants embedded in water ice may also play a role in the 3.6 μm peak properties and these effects have yet to be investigated. Combining VIMS and CIRS measurements will allow us to better characterize the regolith physical proper ties and heat transport mechanisms

  14. Constraints on Saturn's Tropospheric General Circulation from Cassini ISS Images

    Science.gov (United States)

    DelGenio, Anthony D.; Barbara, John M.

    2013-01-01

    An automated cloud tracking algorithm is applied to Cassini Imaging Science Subsystem high-resolution apoapsis images of Saturn from 2005 and 2007 and moderate resolution images from 2011 and 2012 to define the near-global distribution of zonal winds and eddy momentum fluxes at the middle troposphere cloud level and in the upper troposphere haze. Improvements in the tracking algorithm combined with the greater feature contrast in the northern hemisphere during the approach to spring equinox allow for better rejection of erroneous wind vectors, a more objective assessment at any latitude of the quality of the mean zonal wind, and a population of winds comparable in size to that available for the much higher contrast atmosphere of Jupiter. Zonal winds at cloud level changed little between 2005 and 2007 at all latitudes sampled. Upper troposphere zonal winds derived from methane band images are approx. 10 m/s weaker than cloud level winds in the cores of eastward jets and approx. 5 m/s stronger on either side of the jet core, i.e., eastward jets appear to broaden with increasing altitude. In westward jet regions winds are approximately the same at both altitudes. Lateral eddy momentum fluxes are directed into eastward jet cores, including the strong equatorial jet, and away from westward jet cores and weaken with increasing altitude on the flanks of the eastward jets, consistent with the upward broadening of these jets. The conversion rate of eddy to mean zonal kinetic energy at the visible cloud level is larger in eastward jet regions (5.2x10(exp -5) sq m/s) and smaller in westward jet regions (1.6x10(exp -5) sqm/s) than the global mean value (4.1x10(ep -5) sq m/s). Overall the results are consistent with theories that suggest that the jets and the overturning meridional circulation at cloud level on Saturn are maintained at least in part by eddies due to instabilities of the large-scale flow near and/or below the cloud level.

  15. Gene Therapy Targeting HIV Entry

    Directory of Open Access Journals (Sweden)

    Chuka Didigu

    2014-03-01

    Full Text Available Despite the unquestionable success of antiretroviral therapy (ART in the treatment of HIV infection, the cost, need for daily adherence, and HIV-associated morbidities that persist despite ART all underscore the need to develop a cure for HIV. The cure achieved following an allogeneic hematopoietic stem cell transplant (HSCT using HIV-resistant cells, and more recently, the report of short-term but sustained, ART-free control of HIV replication following allogeneic HSCT, using HIV susceptible cells, have served to both reignite interest in HIV cure research, and suggest potential mechanisms for a cure. In this review, we highlight some of the obstacles facing HIV cure research today, and explore the roles of gene therapy targeting HIV entry, and allogeneic stem cell transplantation in the development of strategies to cure HIV infection.

  16. Border Crossing/Entry Data - Border Crossing/Entry Data Time Series tool

    Data.gov (United States)

    Department of Transportation — The dataset is known as “Border Crossing/Entry Data.” The Bureau of Transportation Statistics (BTS) Border Crossing/Entry Data provides summary statistics to the...

  17. Orbits of Saturn's Inner Moons and Other Observations Connected with the 1995-1996 Saturnian Ring Plane Crossing

    Science.gov (United States)

    1997-01-01

    Keck infrared observations of Saturn's E and G rings during Earth's 1995 Ring Plane Crossing are reported along with the NASA's Mauna Kea IR Telescope Facility (IRTF) observations of Saturn's faint outer rings and small moons in the Near-IR Astronomy Program. Observations of the rings and satellites with the 5-m Hale telescope at Palomar Observatory, following the solar crossing of Saturn's ring plane on 19 Nov. 1995, are also addressed. Images of Saturn at radio wavelengths, the data containing information on the structure and composition of the rings as well as the planet's deep atmosphere between the 1- and 10-bar pressure levels, are discussed.

  18. Hydrophobic pocket targeting probes for enteroviruses

    Science.gov (United States)

    Martikainen, Mari; Salorinne, Kirsi; Lahtinen, Tanja; Malola, Sami; Permi, Perttu; Häkkinen, Hannu; Marjomäki, Varpu

    2015-10-01

    Visualization and tracking of viruses without compromising their functionality is crucial in order to understand virus targeting to cells and tissues, and to understand the subsequent subcellular steps leading to virus uncoating and replication. Enteroviruses are important human pathogens causing a vast number of acute infections, and are also suggested to contribute to the development of chronic diseases like type I diabetes. Here, we demonstrate a novel method to target site-specifically the hydrophobic pocket of enteroviruses. A probe, a derivative of Pleconaril, was developed and conjugated to various labels that enabled the visualization of enteroviruses under light and electron microscopes. The probe mildly stabilized the virus particle by increasing the melting temperature by 1-3 degrees, and caused a delay in the uncoating of the virus in the cellular endosomes, but could not however inhibit the receptor binding, cellular entry or infectivity of the virus. The hydrophobic pocket binding moiety of the probe was shown to bind to echovirus 1 particle by STD and tr-NOESY NMR methods. Furthermore, binding to echovirus 1 and Coxsackievirus A9, and to a lesser extent to Coxsackie virus B3 was verified by using a gold nanocluster labeled probe by TEM analysis. Molecular modelling suggested that the probe fits the hydrophobic pockets of EV1 and CVA9, but not of CVB3 as expected, correlating well with the variations in the infectivity and stability of the virus particles. EV1 conjugated to the fluorescent dye labeled probe was efficiently internalized into the cells. The virus-fluorescent probe conjugate accumulated in the cytoplasmic endosomes and caused infection starting from 6 hours onwards. Remarkably, before and during the time of replication, the fluorescent probe was seen to leak from the virus-positive endosomes and thus separate from the capsid proteins that were left in the endosomes. These results suggest that, like the physiological hydrophobic content

  19. 3D modeling of lightning-induced electromagnetic pulses on Venus, Jupiter and Saturn

    Science.gov (United States)

    Pérez-Invernón, Francisco J.; Luque, Alejandro; Gordillo-Vázquez, Francisco J.

    2017-04-01

    Atmospheric electricity is a common phenomenon in some planets of The Solar System. We know that atmospheric discharges exist on Earth and gaseous planets; however, some characteristics of lightning on Saturn and Jupiter as well as their relevance on the effects of lightning in the atmospheres of these planets are still unknown. In the case of Venus, there exist some radio evidences of lightning, but the lack of optical observations suggests exploring indirect methods of detection, such as searching for lightning-induced transient optical emissions from the upper atmosphere. The Akatsuki probe, currently orbiting Venus, is equipped with a camera whose temporal resolution is high enough to detect optical emissions from lightning discharges and to measure nightglow enhancements. In this work, we extend previous models [1,2] to investigate the chemical impact and transient optical emissions produced by possible lightning-emitted electromagnetic pulses (EMP) in Venus, Saturn and Jupiter. Using a 3D FDTD ("Finite Differences Time Domain") model we solve the Maxwell equations coupled with the Langevin equation for electrons [3] and with a kinetic scheme, different for each planetary atmosphere. This method is useful to investigate the temporal and spatial impact of lightning-induced electromagnetic fields in the atmosphere of each planet for different lightning characteristics (e.g. energy released, orientation). This 3D FDTD model allows us to include the saturnian and jovian background magnetic field inclination and magnitude at different latitudes, and to determine the effects of different lightning channel inclinations. Results provide useful information to interpret lightning observations on giant gaseous planets and in the search for indirect optical signals from atmospheric discharge on Venus such as fast nightglow transient enhancements related to lightning as seen on Earth. Furthermore, we underline the observation of electrical discharges characteristics as a

  20. Modelling of the ring current in Saturn's magnetosphere

    Science.gov (United States)

    Giampieri, G.; Dougherty, M.

    2004-02-01

    . The existence of a ring current inside Saturn's magnetosphere was first suggested by smith80 and ness81,ness82, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. connerney83 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set. First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects.

  1. Modelling of the ring current in Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. Giampieri

    2004-01-01

    Full Text Available The existence of a ring current inside Saturn's magnetosphere was first suggested by Smith et al. (1980 and Ness et al. (1981, 1982, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. Connerney et al. (1983 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set. First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects. Key words. Magnetospheric physics (current systems; planetary magnetospheres; plasma sheet

  2. Cloud morphology and dynamics in Saturn's northern polar region

    Science.gov (United States)

    Antuñano, Arrate; del Río-Gaztelurrutia, Teresa; Sánchez-Lavega, Agustín; Rodríguez-Aseguinolaza, Javier

    2018-01-01

    We present a study of the cloud morphology and motions in the north polar region of Saturn, from latitude ∼ 70°N to the pole based on Cassini ISS images obtained between January 2009 and November 2014. This region shows a variety of dynamical structures: the permanent hexagon wave and its intense eastward jet, a large field of permanent ;puffy; clouds with scales from 10 - 500 km, probably of convective origin, local cyclone and anticyclones vortices with sizes of ∼1,000 km embedded in this field, and finally the intense cyclonic polar vortex. We report changes in the albedo of the clouds that delineate rings of circulation around the polar vortex and the presence of ;plume-like; activity in the hexagon jet, in both cases not accompanied with significant variations in the corresponding jets. No meridional migration is observed in the clouds forming and merging in the field of puffy clouds, suggesting that their mergers do not contribute to the maintenance of the polar vortex. Finally, we analyze the dominant growing modes for barotropic and baroclinic instabilities in the hexagon jet, showing that a mode 6 barotropic instability is dominant at the latitude of the hexagon.

  3. Voyager Observations of the Color of Saturn's Ring

    Science.gov (United States)

    Estrada, Paul R.; Cuzzi, Jeffrey N.; Morrison, David (Technical Monitor)

    1994-01-01

    Previously unreduced high resolution Voyager 2 images of Saturn's main rings are used to generate reflectivity (I/F) profiles as a function of radius. Ratios of profiles taken from green, violet, orange, and UV filter images are then produced. The I/F ratios are diagnostic of composition, and provide us with information on the rings' present state of compositional evolution. The rings are extremely reddish in color which suggests that they could not be pure water ice. The most likely candidates for the non-icy components are silicates and organics. The sources of these pollutants are of extreme importance in determining the compositional history of the rings. The radial profiles of ring color ratio exhibit several very interesting properties: (a) broad-scale, fairly smooth, color variations which are only weakly correlated with underlying ring structure (optical depth variations) across the outer C ring and inner B ring as well as the Cassini division region. These variations are probably consistent with ballistic transport; (b) fine-scale, noise-Like (but unquestionably real) color variations across at least the outer two-thirds of the B ring. Not only the "redness" but the spectral shape varies. These variations are currently unexplained. Groundbased spectroscopic observations should be pursued to study the implied compositional heterogeneities on at least the larger scales. This data set will be used for modeling of the color and composition of the main rings using ballistic transport and radiative transfer theories.

  4. Discovery of a Jupiter/Saturn analog with gravitational microlensing.

    Science.gov (United States)

    Gaudi, B S; Bennett, D P; Udalski, A; Gould, A; Christie, G W; Maoz, D; Dong, S; McCormick, J; Szymanski, M K; Tristram, P J; Nikolaev, S; Paczynski, B; Kubiak, M; Pietrzynski, G; Soszynski, I; Szewczyk, O; Ulaczyk, K; Wyrzykowski, L; Depoy, D L; Han, C; Kaspi, S; Lee, C-U; Mallia, F; Natusch, T; Pogge, R W; Park, B-G; Abe, F; Bond, I A; Botzler, C S; Fukui, A; Hearnshaw, J B; Itow, Y; Kamiya, K; Korpela, A V; Kilmartin, P M; Lin, W; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okumura, T; Ohnishi, K; Rattenbury, N J; Sako, T; Saito, To; Sato, S; Skuljan, L; Sullivan, D J; Sumi, T; Sweatman, W L; Yock, P C M; Albrow, M D; Allan, A; Beaulieu, J-P; Burgdorf, M J; Cook, K H; Coutures, C; Dominik, M; Dieters, S; Fouqué, P; Greenhill, J; Horne, K; Steele, I; Tsapras, Y; Chaboyer, B; Crocker, A; Frank, S; Macintosh, B

    2008-02-15

    Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.

  5. 19 CFR 147.11 - Entry.

    Science.gov (United States)

    2010-04-01

    ...) TRADE FAIRS Procedure for Importation § 147.11 Entry. (a) Made in name of fair operator. All entries of articles for a fair shall be made at the port in the name of the fair operator which shall be deemed for... exhibition purposes under the Trade Fair Act of 1959. Mark Number Package and contents Quality Invoice value...

  6. Strategic Entry Deterrence Modeling: Literature Review

    Directory of Open Access Journals (Sweden)

    D. A. Seliverstov

    2017-01-01

    Full Text Available The prime focus in this article is on key findings concerning theoretical aspects of strategic behavior by incumbents to deter market entry of new firms. The author summarizes main lines of scientific research in the topic which give an insight into the patterns of the incumbent’s impact on the behavior of the entrants, the entry deterrence instruments and the consequences of these actions. Today the free entry markets are considered to be a rare phenomenon. The market entry of new firms is associated with significant entry costs, which allow the incumbents to take advantage of their dominant position and derive positive economic profits. In case of entry threat by potential competitors the incumbents take strategic actions aimed at deterring entry and preserving their dominant position. Among the most efficient strategic actions one can emphasize the erection of additional barriers to entry for the newcomers through producing the limit output and price, investments in sunk assets, capacity expansion and product differentiation. Meanwhile by taking strategic actions the incumbents are not always trying to affect the entrant’s costs and profit directly, they often aim at changing the entrant’s expectations regarding future intentions of the incumbents to preserve dominant position.

  7. 27 CFR 27.184 - Entry documents.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Entry documents. 27.184 Section 27.184 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Distilled Spirits From Customs Custody Free of Tax for Use of the United States § 27.184 Entry documents...

  8. Soil gas and radon entry into a simple test structure: Comparison of experimental and modelling results

    DEFF Research Database (Denmark)

    Andersen, C.E.; Søgaard-Hansen, J.; Majborn, B.

    1994-01-01

    A radon test structure has been established at a field site at Riso National Laboratory. Measurements have been made of soil gas entry rates, pressure couplings and radon depletion. The experimental results have been compared with results obtained from measured soil parameters and a two......-dimensional steady-state numerical model of Darcy flow and combined diffusive and advective transport of radon. For most probe locations, the calculated values of the pressure couplings and the radon depletion agree well with the measured values, thus verifying important elements of the Darcy flow approximation......, and the ability of the model to treat combined diffusive and advective transport of radon. However, the model gives an underestimation of the soil gas entry rate. Even if it is assumed that the soil has a permeability equal to the highest of the measured values, the model underestimates the soil gas entry rate...

  9. Stoichiometric parameters of HIV-1 entry.

    Science.gov (United States)

    Zarr, Melissa; Siliciano, Robert

    2015-01-01

    During HIV type 1 (HIV-1) entry, trimers of gp120 bind to CD4 and either the CCR5 or CXCR4 coreceptor on the target cell. The stoichiometric parameters associated with HIV-1 entry remain unclear. Important unanswered questions include: how many trimers must attach to CD4 molecules, how many must bind coreceptors, and how many functional gp120 subunits per trimer are required for entry? We performed single round infectivity assays with chimeric viruses and compared the experimental relative infectivity curves with curves generated by mathematical models. Our results indicate that HIV-1 entry requires only a small number of functional spikes (one or two), that Env trimers may function with fewer than three active subunits, and that there is no major difference in the stoichiometric requirements for CCR5 vs. CXCR4 mediated HIV-1 entry into host cells. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Orion Entry Display Feeder and Interactions with the Entry Monitor System

    Science.gov (United States)

    Baird, Darren; Bernatovich, Mike; Gillespie, Ellen; Kadwa, Binaifer; Matthews, Dave; Penny, Wes; Zak, Tim; Grant, Mike; Bihari, Brian

    2010-01-01

    The Orion spacecraft is designed to return astronauts to a landing within 10 km of the intended landing target from low Earth orbit, lunar direct-entry, and lunar skip-entry trajectories. Al pile the landing is nominally controlled autonomously, the crew can fly precision entries manually in the event of an anomaly. The onboard entry displays will be used by the crew to monitor and manually fly the entry, descent, and landing, while the Entry Monitor System (EMS) will be used to monitor the health and status of the onboard guidance and the trajectory. The entry displays are driven by the entry display feeder, part of the Entry Monitor System (EMS). The entry re-targeting module, also part of the EMS, provides all the data required to generate the capability footprint of the vehicle at any point in the trajectory, which is shown on the Primary Flight Display (PFD). It also provides caution and warning data and recommends the safest possible re-designated landing site when the nominal landing site is no longer within the capability of the vehicle. The PFD and the EMS allow the crew to manually fly an entry trajectory profile from entry interface until parachute deploy having the flexibility to manually steer the vehicle to a selected landing site that best satisfies the priorities of the crew. The entry display feeder provides data from the ENIS and other components of the GNC flight software to the displays at the proper rate and in the proper units. It also performs calculations that are specific to the entry displays and which are not made in any other component of the flight software. In some instances, it performs calculations identical to those performed by the onboard primary guidance algorithm to protect against a guidance system failure. These functions and the interactions between the entry display feeder and the other components of the EMS are described.

  11. Seasonal variation of the position of the magnetodisc in Saturn's magnetosphere

    Science.gov (United States)

    Steckiewicz, Morgane; André, Nicolas; Génot, Vincent; Bouchemit, Myriam; Budnik, Elena; Bourrell, Nataliya; Biegun, Arnaud

    2015-04-01

    Seasonal periodicities in a planetary magnetosphere are driven by the obliquity of the planet which implies the existence of a non-zero magnetospheric tilt between the planet's spin axis and the solar wind direction which varies approximately sinusoidally with time between solstices. Saturn's obliquity is 26.7° which implies well-marked seasons which are reflected in the structure of its magnetosphere. In particular, the location of Saturn's plasmasheet is supposed to be very sensitive to the magnetospheric tilt. Away from equinox when the tilt angle is zero, the solar wind blows from above and below the equatorial plane of Saturn. This asymmetric interaction should result in a seasonal hinging of the magnetodisc at large distances where it should become parallel to the direction of the solar wind. The properties of this region are therefore very interesting to study in details in order to estimate the seasonal impact of the solar wind on Saturn magnetosphere. In the present study we use published Cassini magnetic field observations obtained from early 2005 (northern winter solstice) until late 2013 (northern summer solstice) that includes the transition to equinox in order to identify the seasonal warping of the magnetodisc. We will first show statistically that the magnetodisc is above the rotational equator before the equinox and below after and that the magnetodisc coincides with the rotational equator around the 11th April of 2010. We will then discuss potential implications of this result on the overall structure and dynamics of Saturn's magnetosphere.

  12. 50 CFR 91.22 - Display of contest entries.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Display of contest entries. 91.22 Section... Administering the Contest § 91.22 Display of contest entries. The Federal Duck Stamp Office assigns all eligible entries a number as entries are received. That office displays the entries in numerical order at the...

  13. LABORATORY VOICE DATA ENTRY SYSTEM.

    Energy Technology Data Exchange (ETDEWEB)

    PRAISSMAN,J.L.SUTHERLAND,J.C.

    2003-04-01

    We have assembled a system using a personal computer workstation equipped with standard office software, an audio system, speech recognition software and an inexpensive radio-based wireless microphone that permits laboratory workers to enter or modify data while performing other work. Speech recognition permits users to enter data while their hands are holding equipment or they are otherwise unable to operate a keyboard. The wireless microphone allows unencumbered movement around the laboratory without a ''tether'' that might interfere with equipment or experimental procedures. To evaluate the potential of voice data entry in a laboratory environment, we developed a prototype relational database that records the disposal of radionuclides and/or hazardous chemicals Current regulations in our laboratory require that each such item being discarded must be inventoried and documents must be prepared that summarize the contents of each container used for disposal. Using voice commands, the user enters items into the database as each is discarded. Subsequently, the program prepares the required documentation.

  14. An employee sews thermal insulation material on the front heat shield of the Huygens probe in the PH

    Science.gov (United States)

    1997-01-01

    An employee in the Payload Hazardous Servicing Facility (PHSF) sews thermal insulation material on the front heat shield of the Huygens probe during prelaunch processing testing and integration in that facility, with the probe's back cover in the background. The Huygens probe and the Cassini orbiter being processed at KSC are the two primary components of the Cassini spacecraft, which will be launched on a Titan IVB/Centaur expendable launch vehicle from Cape Canaveral Air Station. Cassini will explore Saturn, its rings and moons for four years. The Huygens probe, designed and developed for the European Space Agency (ESA), will be deployed from the orbiter to study the clouds, atmosphere and surface of Saturn's largest moon, Titan. The orbiter was designed and assembled at NASA's Jet Propulsion Laboratory in California. Following postflight inspections, integration of the 12 science instruments not already installed on the orbiter will be completed. Then, the parabolic high-gain antenna and the propulsion module will be mated to the orbiter, followed by the Huygens probe, which will complete spacecraft integration. The Cassini mission is targeted for an Oct. 6 launch to begin its 6.7-year journey to the Saturnian system. Arrival at the planet is expected to occur around July 1, 2004.

  15. The puzzling structure in Saturn's outer B ring

    Science.gov (United States)

    Nicholson, Philip D.; Hedman, Matt; Buckingham, Rikley

    2017-06-01

    As first noted in Voyager images, the outer edge of Saturn's B ring is strongly perturbed by the 2:1 inner Lindblad resonance with Mimas (Porco \\etal\\ 1984). Cassini imaging and occultation data have revealed a more complex situation, where the expected resonantly-forced m=2 perturbation with an amplitude of 33~km is accompanied by freemodes with m=1, 2, 3, 4 and 5 (Spitale & Porco 2010, Nicholson \\etal\\ 2014a). To date, however, the structure immediately interior to the ring edge has not been examined carefully. We have compared optical depth profiles of the outer 1000~km of the B ring, using a large set of stellar occultations carried out since 2005 by the Cassini VIMS instrument. A search for wavelike structure, using a code written to search for hidden density waves (Hedman \\& Nicholson 2016), reveals a significant signature at a radius of ~117,150 km with a radial wavelength of ~110 km. This appears to be a trailing spiral with m=1 and a pattern speed equal to the local apsidal precession rate, $\\dpi\\simeq5.12\\dd$. Further searches for organized large-scale structure have revealed none with m=2 (as might have been expected), but several additional regions with significant m=1 variations and pattern speeds close to the local value of $\\dpi$. At present, it is unclear if these represent propagating spirals, standing waves, or perhaps features more akin to the eccentric ringlets often seen within gaps in the C ring and Cassini Division (Nicholson \\etal\\ 2014b, French \\etal\\ 2016). Comparisons of sets of profiles from 2008/9, 2012-14 and 2016 seem to show that these structures are changing over time.

  16. Targeted flyby images of propellers in Saturn's A ring

    Science.gov (United States)

    Tiscareno, Matthew S.; Baker, Emily J.; the Cassini ISS Team

    2017-06-01

    As part of its two-part end-of-mission maneuvers, the Cassini has targeted three "propeller moons" for close-range flybys, obtaining images that greatly improve on all previous images in terms of resolution and detailed structure. Propeller moons are ~1 km in size and are embedded in the disk of Saturn's A ring (Tiscareno et al. 2010, ApJL). Unlike the moons Pan and Daphnis, propeller moons have insufficient mass to carve out a fully circumferential gap; instead, we see a propeller-shaped disturbance around the moon (which itself is unseen) as the moon's attempted gap is filled back in, due to the dynamical viscosity of the ring particles.The Cassini Imaging Science Subsystem (ISS) has obtained images of the propeller moon "Santos-Dumont" on both the lit and unlit sides of the rings, and of "Earhart" on the lit side. As of this writing, a final targeted flyby of "Bleriot" on the unlit side of the rings has yet to take place. The resolution of these images is at least 3x to 4x better than those of nearly all previous propeller images, and at least 2x better than those of a small handful of the best previous propeller images.We will present maps of of the propeller structures, with enhanced ability to convert brightness to optical depth and surface density due to information from both the lit and unlit sides of the rings. The images contain more complex structure than is predicted by simple models, which we will describe, and for which we will comment on likely explanations. The central moonlet of each propeller (which has never been seen) should be a couple of pixels across, but we cannot confirm whether they are seen in these images or whether they are obscured by stirred-up ring material.

  17. MIGRATION OF SMALL MOONS IN SATURN's RINGS

    Energy Technology Data Exchange (ETDEWEB)

    Bromley, Benjamin C. [Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States); Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-02-20

    The motions of small moons through Saturn's rings provide excellent tests of radial migration models. In theory, torque exchange between these moons and ring particles leads to radial drift. We predict that moons with Hill radii r {sub H} {approx} 2-24 km should migrate through the A ring in 1000 yr. In this size range, moons orbiting in an empty gap or in a full ring eventually migrate at the same rate. Smaller moons or moonlets-such as the propellers-are trapped by diffusion of disk material into corotating orbits, creating inertial drag. Larger moons-such as Pan or Atlas-do not migrate because of their own inertia. Fast migration of 2-24 km moons should eliminate intermediate-size bodies from the A ring and may be responsible for the observed large-radius cutoff of r {sub H} {approx} 1-2 km in the size distribution of the A ring's propeller moonlets. Although the presence of Daphnis (r {sub H} Almost-Equal-To 5 km) inside the Keeler gap challenges this scenario, numerical simulations demonstrate that orbital resonances and stirring by distant, larger moons (e.g., Mimas) may be important factors. For Daphnis, stirring by distant moons seems the most promising mechanism to halt fast migration. Alternatively, Daphnis may be a recent addition to the ring that is settling into a low inclination orbit in {approx}10{sup 3} yr prior to a phase of rapid migration. We provide predictions of observational constraints required to discriminate among possible scenarios for Daphnis.

  18. Slicing The 2010 Saturn's Storm: Upper Clouds And Hazes

    Science.gov (United States)

    Perez-Hoyos, Santiago; Sanz-Requena, J. F.; Sanchez-Lavega, A.; Hueso, R.

    2012-10-01

    At the end of 2010 a small storm erupted in Saturn's northern mid-latitudes. Starting from a localized perturbation, it grew up to be a global-scale disturbance and cover the whole latitude band by February, 2011 (Fletcher et al. 2011, Science 332; Sánchez-Lavega et al. 2011, Nature 475; Fischer et al. 2011, Nature 475). By June, 2011 the storm was facing its end and gradually disappeared (Sánchez-Lavega et al. 2012, Icarus 220). In this work we use the observations acquired by the Cassini ISS instrument during the whole process to investigate the vertical cloud and haze structure above the ammonia condensation level (roughly 1 bar). Cassini ISS observations cover visual wavelengths from the blue to the near-infrared including two methane absorption bands. Such observations have been modeled using a radiative transfer code which reproduces the atmospheric reflectivity as a function of observation/illumination geometry and wavelength together with a retrieval technique to find maximum likelihood atmospheric models. This allows to investigate some atmospheric parameters: cloud-top pressures, aerosol optical thickness and particle absorption, among others. We will focus on two aspects: (1) maximum likelihood models for the undisturbed reference atmosphere in the 15°N to 45°N band before and after the disturbance; (2) models for particular structures during the development of the global-scale phenomenon. Our results show a general increase of particle density and single-scattering albedo inside the storm. However, some discrete features showing anomalous structure and related to the storm peculiar dynamics will also be discussed. Acknowledgments: This work was supported by the Spanish MICIIN project AYA2009-10701 with FEDER funds, by Grupos Gobierno Vasco IT-464-07 and by Universidad País Vasco UPV/EHU through program UFI11/55.

  19. N-body Survey of Viscous Overstability in Saturn's Rings

    Science.gov (United States)

    Salo, Heikki J.; Schmidt, J.; Sremcevic, M.; Sremcevic, M.; Spahn, F.

    2008-09-01

    The viscous overstability of dense collisional rings offers a promising explanation for the small scale radial density variations in the B and the inner A ring of Saturn. Viscous overstability, in the form of spontaneous growth of axisymmetric oscillations, was first directly demonstrated in the selfgravitating N-body simulations (Salo etal. 2001). In contrast to previous isothermal hydrodynamical analysis (Schmit & Tscharnuter 1995), which suggested that practically any dense ring should be overstable, our N-body simulations indicated that a steep rise of viscosity with optical depth was required. In particular, a selfgravitating system of identical particles following the Bridges etal. (1984) elasticity formula was found to become overstable for optical depths τ > 1., forming oscillations in about 100 meter scale. In these simulations the axisymmetric oscillations were found to coexist with the inclined selfgravity wake structures. In addition, a basically similar overstability was seen in nongravitating simulations, but shifted to very high optical depths, or in simulations were just the vertical selfgravity was included, leading to an enhanced impact frequency and viscosity. Although an improved non-isothermal hydrodynamical analysis (Spahn et al. 2000, Schmidt et al. 2001) was able to describe quantitatively these non-selfgravitating cases, even in the weakly nonlinear regime (Schmidt & Salo, 2003), a reliable study of realistic selfgravitating rings must rely on numerical experiments. We report the results of a new N-body survey of viscous overstability. For example, we study the optical depth and gravity strength regimes which lead to the excitation of overstability, co-existence of overstabilities and gravity wakes, or to the suppression of overstability in the case of very strong wakes. Also the effects of various factors (particle elasticity, surface friction and adhesion, size distribution) on the threshold density required for the triggering of

  20. Photometric modeling of viscous overstability in Saturn's rings

    Science.gov (United States)

    Salo, H.

    2011-10-01

    The viscous overstability of dense planetary rings offers a plausible mechanism for the generation of observed ˜ 150 m radial density variations in the B and the inner A ring of Saturn (Colwell et al. 2007, Thomson et al. 2007). Viscous overstability, in the form of spontaneous growth of axisymmetric oscillations, arises naturally in N-body simulations, in the limit of high impact frequency and moderately weak selfgravity (Salo et al. 2001, Schmidt et al. 2001; see also Schmidt et al. 2009). For example, a selfgravitating system of identical particles with internal density ˜ half of solid ice, and following the Bridges et al. (1984) elasticity formula, becomes overstable for optical depths ? > 1, forming oscillations in about 100 meter scale. Like self-gravity wakes, with their typical ˜ 20° trailing pitch angle, overstable oscillations lead to a longitude-dependent brightness of the rings. Due to their axisymmetric nature, the expected longitude of minimum brightness is shifted to ring ansae. However, according to simulations, the axisymmetric oscillations may coexist with the inclined selfgravity wake structures, which can lead to complicated photometric behavior, depending on properties of the simulated system. The overstable systems may also exhibit amplitude modulations (in km-scales), arising from the mutual beating patterns of the basics overstable oscillations. New results of photometric modeling of viscously overstable dynamical simulations systems are reported, related to the above mentioned topics. The Monte Carlo method of Salo and Karjalainen (2003) is used, previously applied to modeling of photometric signatures of selfgravity wakes (Salo et al. 2004, French et al. 2007), scattering properties of propeller stuctures (Sremcevic et al., 2007), and to the intepretation of elevation-angle dependent opposition effect seen in HST data (Salo and French 2010). For example, the possible observable signatures of amplitude modulations are explored.

  1. Shallow Water Simulations of the Three Last Saturn's Giant Storms

    Science.gov (United States)

    Garcia-Melendo, Enrique; Sanchez-Lavega, Agustin

    2015-11-01

    Shallow Water (SW) simulations are used to present a unified study of the polar (1960), equatorial (1990), and mid-latitude (2010) major storms in Saturn nicknamed as Great White Spots (GWS). The 2010 GWS appeared at +40, moved at -30 m s-1 where the Coriolis force is predominant producing an open anticyclone with a high speed peripheral circulation and a cloud front around the convective source; a long-lived anticyclone; and strong zonal advection on the south part of the storm forming a turbulent region. The 1990 GWS onset took place near the equator, between +12 and +5, on the broad prograde equatorial jet (450 m s-1) where equatorial dynamics dominated producing a storm nucleus, with rapid expansion to the west of a Kelvin-Helmholtz instability on the north side of the perturbation due to advection, and trapped equatorial waves which also expanded the storm to the east around the equator. The 1960 GWS appeared at high latitudes (+56) where Coriolis force is predominant in a region where zonal wind velocity is 0 m s-1. SW simulations predict a strong injection of relative vorticity which may produce large anticyclones on the anticyclonic side of the zonal profile, and a quick turbulent expansion on the background cyclonic regions at mid and high latitudes. In general, simulations indicate that negative relative vorticity injected by the storms also defines the natural interaction with the zonal winds at latitudes where the Coriolis force is dominant dictating its large scale dynamical behavior. Numerical experiments on the 1990 storm indicate that the onset of the storm can only be reproduced if the Voyager era background zonal flow is used, which suggests that it dominated the circulation dynamics at the storm’s outbreak region at that time. They also reproduce its most important morphological features, and show the production of planetary waves and turbulence. We discuss possible mechanism for the observed equatorial jet alterations during the storm

  2. Titan Saturn System Mission (TSSM) Enables Comparative Climatology with Earth

    Science.gov (United States)

    Reh, Kim; Lunine, J.; Coustenis, A.; Matson, D.; Beauchamp, P.; Erd, C.; Lebreton, J.

    2009-09-01

    Titan is a complex world more like the Earth than any other: it has a dense mostly nitrogen atmosphere and active climate and meteorological cycles where the working fluid, methane, behaves under Titan conditions the way that water does on Earth. Its geology, from lakes and seas to broad river valleys and mountains, while carved in ice is, in its balance of processes, again most like Earth. Beneath this panoply of Earth-like processes an ice crust floats atop what appears to be a liquid water ocean. The Titan Saturn System Mission would seek to understand Titan as a system, in the same way that one would ask this question about Venus, Mars, and the Earth. How are distinctions between Titan and other worlds in the solar systems understandable in the context of the complex interplay of geology, hydrology, meteorology, and aeronomy? Is Titan an analogue for some aspect of Earth's history, past or future? Why is Titan endowed with an atmosphere when Ganymede is not? Titan is also rich in organic molecules_more so in its surface and atmosphere than anyplace in the solar system, including Earth (excluding our vast carbonate sediments). These molecules were formed in the atmosphere, deposited on the surface and, in coming into contact with liquid water may undergo an aqueous chemistry that could replicate aspects of life's origins. The second goal of the proposed TSSM mission is to understand the chemical cycles that generate and destroy organics and assess the likelihood that they can tell us something of life's origins. This work was performed at the Jet Propulsion Laboratory-California Institute of Technology, under contract to NASA.

  3. Retrovirus Entry by Endocytosis and Cathepsin Proteases

    Directory of Open Access Journals (Sweden)

    Yoshinao Kubo

    2012-01-01

    Full Text Available Retroviruses include infectious agents inducing severe diseases in humans and animals. In addition, retroviruses are widely used as tools to transfer genes of interest to target cells. Understanding the entry mechanism of retroviruses contributes to developments of novel therapeutic approaches against retrovirus-induced diseases and efficient exploitation of retroviral vectors. Entry of enveloped viruses into host cell cytoplasm is achieved by fusion between the viral envelope and host cell membranes at either the cell surface or intracellular vesicles. Many animal retroviruses enter host cells through endosomes and require endosome acidification. Ecotropic murine leukemia virus entry requires cathepsin proteases activated by the endosome acidification. CD4-dependent human immunodeficiency virus (HIV infection is thought to occur via endosomes, but endosome acidification is not necessary for the entry whereas entry of CD4-independent HIVs, which are thought to be prototypes of CD4-dependent viruses, is low pH dependent. There are several controversial results on the retroviral entry pathways. Because endocytosis and endosome acidification are complicatedly controlled by cellular mechanisms, the retrovirus entry pathways may be different in different cell lines.

  4. Novel Approaches to Inhibit HIV Entry

    Directory of Open Access Journals (Sweden)

    Chukwuka A. Didigu

    2012-02-01

    Full Text Available Human Immunodeficiency Virus (HIV entry into target cells is a multi-step process involving binding of the viral glycoprotein, Env, to its receptor CD4 and a coreceptor—either CCR5 or CXCR4. Understanding the means by which HIV enters cells has led to the identification of genetic polymorphisms, such as the 32 base-pair deletion in the ccr5 gene (ccr5∆32 that confers resistance to infection in homozygous individuals, and has also resulted in the development of entry inhibitors—small molecule antagonists that block infection at the entry step. The recent demonstration of long-term control of HIV infection in a leukemic patient following a hematopoietic stem cell transplant using cells from a ccr5∆32 homozygous donor highlights the important role of the HIV entry in maintaining an established infection and has led to a number of attempts to treat HIV infection by genetically modifying the ccr5 gene. In this review, we describe the HIV entry process and provide an overview of the different classes of approved HIV entry inhibitors while highlighting novel genetic strategies aimed at blocking HIV infection at the level of entry.

  5. Size distribution of particles in planetary rings. [applied to Saturn and terrestrial planets

    Science.gov (United States)

    Greenberg, R.; Davis, D. R.; Hartmann, W. K.; Chapman, C. R.

    1977-01-01

    Harris (1975) has suggested that the maximum size of particles in a planetary ring is controlled by collisional fragmentation rather than tidal stress. While this conclusion is probably true, estimated radius limits must be revised upward from Harris' values of a few kilometers by at least an order of magnitude. Accretion of particles within the Roche limit is also possible. These considerations affect theories concerning the evolution of Saturn's rings, of the moon, and of possible former satellites of Mercury and Venus. In the case of Saturn's rings, comparison of various theoretical scenarios with available observational evidence suggests that the rings formed from the breakup of larger particles rather than from original condensation as small particles. This process implies a distribution of particle sizes in Saturn's rings possibly ranging up to about 100 km but with most of the cross section in centimeter-scale particles.

  6. Photopolarimetry from voyager 2; preliminary results on saturn, titan, and the rings.

    Science.gov (United States)

    Lane, A L; Hord, C W; West, R A; Esposito, L W; Coffeen, D L; Sato, M; Simmons, K E; Pomphrey, R B; Morris, R B

    1982-01-29

    The Voyager 2 photopolarimeter was reprogrammed prior to the August 1981 Saturn encounter to perform orthogonal-polarization, two-color measurements on Saturn, Titan, and the rings. Saturn's atmosphere has ultraviolet limb brightening in the mid-latitudes and pronounced polar darkening north of 65 degrees N. Titan's opaque atmosphere shows strong positive polarization at all phase angles (2.7 degrees to 154 degrees ), and no single-size spherical particle model appears to fit the data. A single radial stellar occultation of the darkened, shadowed rings indicated a ring thickness of less than 200 meters at several locations and clear evidence for density waves caused by satellite resonances. Multiple, very narrow strands of material were found in the Encke division and within the brightest single strand of the F ring.

  7. Skirting Saturn's Rings and Skimming Its Cloud Tops: Planning Cassini's End of Mission

    Science.gov (United States)

    Manor-Chapman, Emily; Magee, Kari; Brooks, Shawn; Edgington, Scott; Heventhal, William; Sturm, Erick

    2014-01-01

    In October 2010, the Cassini spacecraft embarked on the seven-year Solstice Mission. The mission will culminate with a spectacular series of orbits that bring Cassini between Saturn's innermost ring, the D ring, and the cloud tops of the planet. The spacecraft will make its closest passages ever to the planet allowing for unprecedented science to be collected on Saturn and its rings. These final orbits will expose the spacecraft to new environments, which presents a number of challenges to planning the final mission phase. While these challenges will require adaptations to planning processes and operations, they are not insurmountable. This paper describes the challenges identified and the steps taken to mitigate them to enable collection of unique Saturn system science.

  8. Cassini Operational Sun Sensor Risk Management During Proximal Orbit Saturn Ring Plane Crossings

    Science.gov (United States)

    Bates, David M.

    2016-01-01

    NASA's Cassini Spacecraft, launched on October 15th, 1997 which arrived at Saturn on June 30th, 2004, is the largest and most ambitious interplanetary spacecraft in history. As the first spacecraft to achieve orbit at Saturn, Cassini has collected science data throughout its four-year prime mission (2004–08), and has since been approved for a first and second extended mission through 2017. As part of the final extended missions, Cassini will begin an aggressive and exciting campaign of high inclination, low altitude flybys within the inner most rings of Saturn, skimming Saturn’s outer atmosphere, until the spacecraft is finally disposed of via planned impact with the planet. This final campaign, known as the proximal orbits, requires a strategy for managing the Sun Sensor Assembly (SSA) health, the details of which are presented in this paper.

  9. The Concentric Maclaurin Spheroid method with tides and a rotational enhancement of Saturn's tidal response

    Science.gov (United States)

    Wahl, Sean M.; Hubbard, William B.; Militzer, Burkhard

    2017-01-01

    We extend to three dimensions the Concentric Maclaurin Spheroid method for obtaining the self-consistent shape and gravitational field of a rotating liquid planet, to include a tidal potential from a satellite. We exhibit, for the first time, an important effect of the planetary rotation rate on tidal response of gas giants, whose shape is dominated by the centrifugal potential from rapid rotation. Simulations of planets with fast rotation rates like those of Jupiter and Saturn, exhibit significant changes in calculated tidal love numbers knm when compared with non-rotating bodies. A test model of Saturn fitted to observed zonal gravitational multipole harmonics yields k2 = 0.413 , consistent with a recent observational determination from Cassini astrometry data (Lainey et al., 2016.). The calculated love number is robust under reasonable assumptions of interior rotation rate, satellite parameters, and details of Saturn's interior structure. The method is benchmarked against several published test cases.

  10. The evidences of latitudinal asymmetry of the ammonia absorption on Saturn

    Science.gov (United States)

    Tejfel, V. G.; Karimov, A. M.; Bondarenko, N. N.; Kharitonova, G. A.

    2015-10-01

    450 zonal CCD-spectrograms, recorded by scanning the disk of Saturn during its equinox at the beginning of 2009, were processed to find the variation of the absorption band of ammonia NH3 647 nm. This band overlaps with the short-wavelength wing of the absorption band of methane CH4 667 nm, therefore, to highlight the ammonia absorption spectra were used Uranus and laboratory spectra of methane. It was found that ammonia absorption is enhanced in the northern hemisphere of Saturn, as well as relatively weak bands of methane in contrast with stronger CH4 bands [1]. It may indicate on the North-South asymmetry in the density of the deeper parts of the ammonia cloud layer of Saturn.

  11. Entry Mode and Performance of Nordic Firms

    DEFF Research Database (Denmark)

    Wulff, Jesper

    2015-01-01

    This study investigates whether the relationship between mode of international market entry and non-location bound international experience is weaker for firms that are large or have a high foreign to total sales ratio, labeled multinational experience. Empirical evidence based on 250 foreign...... market entries made by Norwegian, Danish and Swedish firms suggests that the association between equity mode choice and non-location bound international experience diminishes in the presence of higher levels of multinational experience. Furthermore, firms whose entry mode choice is predicted by the model...

  12. Foreign Entry and Heterogeneous Growth of Firms

    DEFF Research Database (Denmark)

    Deng, Paul Duo; Jefferson, Gary H.

    We adopt the framework of Schumpeterian creative destruction formalized by Aghion et al. (2009) to analyze the impact of foreign entry on the productivity growth of domestic firms. In the face of foreign entry, domestic firms exhibit heterogeneous patterns of growth depending on their technological...... distance from foreign firms. Domestic firms with smaller technological distance from their foreign counterparts tend to experience faster productivity growth, while firms with larger technological distance tend to lag further behind. We test this hypothesis using a unique firm-level data of Chinese...... manufacturing. Our empirical results confirm that foreign entry indeed generates strong heterogeneous growth patterns among domestic firms....

  13. Looking Forward to Cassini's Proximal Orbits: the Innermost Radiation Belt of Saturn

    Science.gov (United States)

    Cooper, John F.; Kollmann, P.; Paranicas, C.; Mitchell, D. G.; Hedman, M. M.; Edgington, S. G.; Sittler, E. C.; Hartle, R. E.; Johnson, R. E.; Sturner, S. J.; Cassini Proximal Hazard Working Group

    2013-10-01

    The Cassini mission to Saturn will conclude with over twenty flybys of the equatorial gap region between Saturn's upper atmosphere and the inner D ring. This region at 62,000 - 65,000 kilometers from the center of Saturn is of comparable width to the inner Van Allen radiation belt of Earth and could contain Saturn's innermost belt of presently uncertain intensity and impact on the Cassini spacecraft. As first proposed by Cooper [BAAS 40(3), 460, 2008] this innermost belt could be populated to potentially very high intensities by protons and electrons from cosmic ray albedo neutron decay. The primary neutron source at high energies above 10 MeV would be from galactic cosmic ray interactions with the main rings of Saturn, but more recent work suggests a secondary source at lower energies from similar interactions with Saturn's upper atmosphere. At keV energies a third source from magnetospheric energetic neutral atom interactions with the exospheric gas extending through the gap region could be effective as observed earlier by Cassini. A fourth source includes eV - keV ions from low-energy neutral atom ejection out of the ring atmosphere. Ions from the ring ionosphere were also observed by Cassini. Since trapping lifetimes of keV - GeV protons due to radial diffusion in the gap region are projected to be extremely long, correspondingly high intensities could arise unless there was sufficient exospheric gas and ring material to reduce lifetimes far below the diffusion limit. Limits from new modeling are presented for the potential range of trapped particle intensities at MeV - GeV energies. Apart from the potential radiation and other hazards, this first exploration of the gap region will provide a fascinating conclusion to the Cassini mission.

  14. In-situ measurements of ions and neutrals near Saturn's F-ring

    Science.gov (United States)

    Perry, M. E.; Cravens, T. E.; Smith, H. T.; Perryman, R. S.; Tseng, W. L.; Teolis, B. D.; Waite, J. H., Jr.; McNutt, R. L., Jr.

    2017-09-01

    Each week from December 2016 until April 2017, Cassini dove through a gap in the F-ring. During several of those traverses, the orientation of Cassini's Ion and Neutral Mass Spectrometer (INMS [1]) enabled in situ measurements of both ions and neutrals, providing data that contribute to improving our understanding of the rings, their interaction with Saturn, and the influence of the magnetosphere. The Enceladus plumes, Saturn's atmosphere, and ring sputtering (photolysis and radiolysis) are all potential sources of F-ring particles.

  15. Temperature Variations of Saturn Rings with Viewing Geometries from Prime to Equinox Cassini Missions

    Science.gov (United States)

    Deau, E. A.; Spilker, L. J.; Morishima, R.; Brooks, S.; Pilorz, S.; Altobelli, N.

    2011-01-01

    After more than six years in orbit around Saturn, the Cassini Composite Infrared Spectrometer (CIRS) has acquired an extensive set of measurements of Saturn's main rings (A, B, C and Cassini Division) in the thermal infrared. Temperatures were retrieved for the lit and unlit rings over a variety of ring geometries that include phase angle, solar and spacecraft elevations and local time. We show that some of these parameters (solar and spacecraft elevations, phase angle) play a role in the temperature variations in the first order, while the others (ring and particle local time) produced second order effects. The results of this comparison will be presented.

  16. Comparison of density waves in the rings of Saturn and Uranus

    Science.gov (United States)

    Yanamandra-Fisher, Padmavati A.

    1992-01-01

    The similarity of density waves in the rings of Saturn and Uranus are addressed. It is found that all ring systems are grossly similar in that they all encircle the primary in its equatorial plane and exhibit responses to resonant satellite perturbations. The dominant response of Saturn's rings is the clearing of gaps and generation of density and bending waves. The Uranian rings appear to be confined by the presence of shepherd satellites. Three possible density waves have been identified, two in the epsilon ring and one in the delta ring.

  17. Using Saturn's Rings as a Diagnostic of its Internal Dierential Rotation

    Science.gov (United States)

    El Moutamid, Maryame; Hedman, Matthew M.; Nicholson, Philip D.

    2017-10-01

    This is the end; Cassini crashes into Saturn’s atmosphere, providing unique data and results thanks to the last orbits. Cassini have spent 13 years in orbit around Saturn, during this period, scientists from the world have collected data from many instruments and have learned a great deal about the planet itself, its rings and satellites, and the connection between them. I will present some of the results some dynamical structures on the main rings of Saturn and their dynamical connection with the interior of the planet.

  18. Global climate modeling of Saturn's atmosphere: exploration of seasonal variability and stratospheric dynamics

    Science.gov (United States)

    Spiga, A.; Guerlet, S.; Millour, E.; Sylvestre, M.; Fouchet, T.; Wordsworth, R.; Leconte, J.; Forget, F.; Hourdin, F.

    2013-12-01

    A leap forward on our knowledge of Saturn's stratosphere has resulted from the combination of orbital observations on board the Cassini spacecraft and state-of-the-art ground-based observations. Maps of temperature and hydrocarbons in Saturn's stratosphere revealed puzzling anomalies: equatorial oscillations with a period of about half a Saturn year, meridional circulations affecting the hydrocarbons' distribution, including possible effects of rings shadowing, "beacons" associated with the powerful 2010 Great White Spot. Those signatures, reminiscent of fundamental wave-driven phenomena in the Earth's middle atmosphere (e.g., Quasi-Biennal Oscillation, Brewer-Dobson circulation), cannot be reproduced by 1D photochemical and radiative models. This motivated us to develop a complete 3D General Circulation Model (GCM) for Saturn, based on the LMDz hydrodynamical core, to explore the circulation, seasonal variability, and wave activity in Saturn's atmosphere. In order to closely reproduce Saturn's radiative forcing, a particular emphasis was put in obtaining fast and accurate radiative transfer calculations. Our radiative model uses correlated-k distributions and spectral discretization tailored for Saturn's atmospheric composition (methane, ethane, acetylene). In addition to this, we include CIA absorption (hydrogen and helium), internal heat flux, ring shadowing, and aerosols. A systematic study is carried out on the sensitivity of the model to spectral discretization, spectroscopic databases, and aerosol scenarios (varying particle sizes, opacities and vertical structures). Temperature fields obtained with this new radiative equilibrium model are compared to that inferred from Cassini/CIRS observations. In the troposphere, our model reproduces the observed temperature knee caused by heating at the top of the tropospheric aerosol layer. In the lower stratosphere, the overall meridional gradient between the summer and the winter hemispheres agrees with observations

  19. Validation of Monte-Carlo Geant4 code for Saturne 43 LINAC

    OpenAIRE

    J. EL Bakkali; El Bardouni, T.; M. Zoubair; H. Boukhal

    2013-01-01

    The aim of this study was to model the 12 MV photon beam from a Saturne 43 LINAC configuring a 10×10 cm2 radiation field, this by finding the required adjustments to the electron source parameters namely the spot size, shape and energy distribution. The MC simulation tool Geant4 version 4.9.4 was used with rocks clustering software and Geant4 MPI Interface to parallelize our Geant4-based application. In this work, we have developed a user code for Saturne 43 LINAC simulation. This code has th...

  20. Study for the validation of Code Saturne for turbulent flow simulations

    OpenAIRE

    Amat Foraster, Jordi

    2017-01-01

    Introduction. Code_Saturne is a multipurpose Computational Fluid Dynamics (CFD) software package, which has been developed by EDF (France). Code_Saturne's open-source status allows for answers to specific needs that cannot easily be made available in commercial "black box" packages. It is also one of the 12 solvers selected by the Unified European Application Benchmark Suite (UEABS) inside PRACE and has been thoroughly proved to scale on large systems.Goal.The goal of this project is to use h...

  1. Market entry strategies into the BRIC countries

    DEFF Research Database (Denmark)

    Boyd, Britta; Dyhr Ulrich, Anna Marie

    2014-01-01

    Based on a sample of 177 exporting SMEs, this study investigates what market entry strategy is used by Danish family and non-family businesses. From a resource-based view, three critical internal factors (risk, flexibility and control) affecting the entry mode choice into the BRIC markets...... compared to non-family firms. Furthermore, the Danish exporters regarded China as being the most established of the four BRIC markets which could be seen in their willingness to use high control entry modes in China. Finally, non-family firms are more concerned about higher flexibility and lower control...... when entering the BRIC markets. In contrast, family firms choose high commitment entry modes which involve high risk and low flexibility when entering the BRIC markets. Further implications discuss the suitability of export strategies to BRIC markets for managers of Danish family and non-family firms....

  2. Adaptive Text Entry for Mobile Devices

    DEFF Research Database (Denmark)

    Proschowsky, Morten Smidt

    to improve the models of human motor behaviour. TUP-Key is a variant of TUP, designed for 12 key phone keyboards. It is introduced in the thesis but has not been implemented or evaluated. Both text entry methods support adaptive context-aware language models. YourText is a framework for adaptive context...... for mobile devices and a framework for adaptive context-aware language models. Based on analysis of current text entry methods, the requirements to the new text entry methods are established. Transparent User guided Prediction (TUP) is a text entry method for devices with one dimensional touch input. It can...... be touch sensitive wheels, sliders or similar input devices. The interaction design of TUP is done with a combination of high level task models and low level models of human motor behaviour. Three prototypes of TUP are designed and evaluated by more than 30 users. Observations from the evaluations are used...

  3. Border Crossing/Entry Data - Boarder Crossing

    Data.gov (United States)

    Department of Transportation — Border Crossing/Entry Data provides summary statistics for incoming crossings at the U.S.-Canadian and the U.S.-Mexican border at the port level. Data are available...

  4. The Effects of Entry in Bilateral Oligopoly

    Directory of Open Access Journals (Sweden)

    Alex Dickson

    2013-06-01

    Full Text Available The purpose of this paper is to study the effects of entry into the market for a single commodity in which both sellers and buyers are permitted to interact strategically. With the inclusion of an additional seller, the market is quasi-competitive: the price falls and volume of trade increases, as expected. However, contrary to the conventional wisdom, existing sellers’ payoffs may increase. The conditions under which entry by new sellers raises the equilibrium payoffs of existing sellers are derived. These depend in an intuitive way on the elasticity of a strategic analog of demand and the market share of existing sellers, and encompass entirely standard economic environments. Similar results are derived relating to the entry of additional buyers and the effects of entry on both sides of the market are investigated.

  5. Remodeling of Calcium Entry Pathways in Cancer.

    Science.gov (United States)

    Villalobos, Carlos; Sobradillo, Diego; Hernández-Morales, Miriam; Núñez, Lucía

    2016-01-01

    Ca(2+) entry pathways play important roles in control of many cellular functions, including long-term proliferation, migration and cell death. In recent years, it is becoming increasingly clear that, in some types of tumors, remodeling of Ca(2+) entry pathways could contribute to cancer hallmarks such as excessive proliferation, cell migration and invasion as well as resistance to cell death or survival. In this chapter we briefly review findings related to remodeling of Ca(2+) entry pathways in cancer with emphasis on the mechanisms that contribute to increased store-operated Ca(2+) entry (SOCE) and store-operated currents (SOCs) in colorectal cancer cells. Finally, since SOCE appears critically involved in colon tumorogenesis, the inhibition of SOCE by aspirin and other NSAIDs and its possible contribution to colon cancer chemoprevention is reviewed.

  6. Formative Assessment Probes

    Science.gov (United States)

    Eberle, Francis; Keeley, Page

    2008-01-01

    Formative assessment probes can be effective tools to help teachers build a bridge between students' initial ideas and scientific ones. In this article, the authors describe how using two formative assessment probes can help teachers determine the extent to which students make similar connections between developing a concept of matter and a…

  7. Developing Quantitative Models for Auditing Journal Entries

    OpenAIRE

    Argyrou, Argyris

    2013-01-01

    The thesis examines how the auditing of journal entries can detect and prevent financial statement fraud. Financial statement fraud occurs when an intentional act causes financial statements to be materially misstated. Although it is not a new phenomenon, financial statement fraud has attracted much publicity in the wake of numerous cases of financial malfeasance (e.g. ENRON, WorldCom). Existing literature has provided limited empirical evidence on the link between auditing journal entrie...

  8. Entry modes of European firms in Vietnam

    OpenAIRE

    Daniel Simonet

    2012-01-01

    Purpose: The purpose of the paper is to explore the entry modes of EU firms setting up operations in Vietnam. Design/methodology/approach: we use a case study approach on Haymarket, Cadbury, Creative Education, Fairchild, Aventis and Artemisinin and Farming International using interviews from managerial professionals in Vietnam. Findings: Despite the fact that Vietnam has been opening up for more than 20 years, licensing is the preferred entry mode because of the risks involved in ventur...

  9. Advanced Restricted Area Entry Control System (ARAECS)

    OpenAIRE

    Appleton, Robert; Casillas, Jose; Scales, Gregory; Green, Robert; Niehoff, Mellissa; Fitzgerald, David; Ouellette, David

    2014-01-01

    Approved for public release; distribution is unlimited The Navy requires a capability for effective and efficient entry control for restricted areas that house critical assets. This thesis describes an Advanced Restricted Area Entry Control System (ARAECS) to meet this requirement. System requirements were obtained from existing governing documentation as well as stakeholder inputs. A functional architecture was developed and then modeled using the Imagine That Inc. ExtendSim tool. Factors...

  10. Limit pricing and secret barriers to entry

    OpenAIRE

    Brighi, Luigi; D'Amato, Marcello

    2014-01-01

    We study a two periods entry game where the incumbent .rm, who has private information about his own production costs, makes a non observable long run investment choice, along with a pricing decision observed by the entrant. The investment choice affects both post-entry competition and first period cost of production, so that the cost of signaling becomes endogenous. The game is solved following Bayes-Nash requirements, the intuitive criterion is used to constrain off-equilibrium beliefs. Whe...

  11. Inflatable traversing probe seal

    Science.gov (United States)

    Trimarchi, Paul A.

    1991-01-01

    An inflatable seal acts as a pressure-tight zipper to provide traversing capability for instrumentation rakes and probes. A specially designed probe segment with a teardrop cross-section in the vicinity of the inflatable seal minimizes leakage at the interface. The probe is able to travel through a lengthwise slot in a pressure vessel or wind tunnel section, while still maintaining pressure integrity. The design uses two commercially available inflatable seals, opposing each other, to cover the probe slot in a wind tunnel wall. Proof-of-concept tests were conducted at vessel pressures up to 30 psig, with seals inflated to 50 psig, showing no measurable leakage along the seal's length or around the probe teardrop cross-section. This seal concept can replace the existing technology of sliding face plate/O-ring systems in applications where lengthwise space is limited.

  12. Orion Capsule Handling Qualities for Atmospheric Entry

    Science.gov (United States)

    Tigges, Michael A.; Bihari, Brian D.; Stephens, John-Paul; Vos, Gordon A.; Bilimoria, Karl D.; Mueller, Eric R.; Law, Howard G.; Johnson, Wyatt; Bailey, Randall E.; Jackson, Bruce

    2011-01-01

    Two piloted simulations were conducted at NASA's Johnson Space Center using the Cooper-Harper scale to study the handling qualities of the Orion Command Module capsule during atmospheric entry flight. The simulations were conducted using high fidelity 6-DOF simulators for Lunar Return Skip Entry and International Space Station Return Direct Entry flight using bank angle steering commands generated by either the Primary (PredGuid) or Backup (PLM) guidance algorithms. For both evaluations, manual control of bank angle began after descending through Entry Interface into the atmosphere until drogue chutes deployment. Pilots were able to use defined bank management and reversal criteria to accurately track the bank angle commands, and stay within flight performance metrics of landing accuracy, g-loads, and propellant consumption, suggesting that the pilotability of Orion under manual control is both achievable and provides adequate trajectory performance with acceptable levels of pilot effort. Another significant result of these analyses is the applicability of flying a complex entry task under high speed entry flight conditions relevant to the next generation Multi Purpose Crew Vehicle return from Mars and Near Earth Objects.

  13. Evolved atmospheric entry corridor with safety factor

    Science.gov (United States)

    Liang, Zixuan; Ren, Zhang; Li, Qingdong

    2018-02-01

    Atmospheric entry corridors are established in previous research based on the equilibrium glide condition which assumes the flight-path angle to be zero. To get a better understanding of the highly constrained entry flight, an evolved entry corridor that considers the exact flight-path angle is developed in this study. Firstly, the conventional corridor in the altitude vs. velocity plane is extended into a three-dimensional one in the space of altitude, velocity, and flight-path angle. The three-dimensional corridor is generated by a series of constraint boxes. Then, based on a simple mapping method, an evolved two-dimensional entry corridor with safety factor is obtained. The safety factor is defined to describe the flexibility of the flight-path angle for a state within the corridor. Finally, the evolved entry corridor is simulated for the Space Shuttle and the Common Aero Vehicle (CAV) to demonstrate the effectiveness of the corridor generation approach. Compared with the conventional corridor, the evolved corridor is much wider and provides additional information. Therefore, the evolved corridor would benefit more to the entry trajectory design and analysis.

  14. Monitoring Saturn's Upper Atmosphere Density Variations Using Helium 584 Airglow

    Science.gov (United States)

    Parkinson, Chris

    2017-10-01

    The study of He 584 Å brightnesses is interesting as the EUV (Extreme UltraViolet) planetary airglow have the potential to yield useful information about mixing and other important parameters in its thermosphere. Resonance scattering of sunlight by He atoms is the principal source of the planetary emission of He 585 Å. The principal parameter involved in determining the He 584 Å albedo are the He volume mixing ratio, f_He, well below the homopause. Our main science objective is to estimate the helium mixing ratio in the lower atmosphere. Specifically, He emissions come from above the homopause where optical depth trau=1 in H2 and therefore the interpretation depends mainly on two parameters: He mixing ratio of the lower atmosphere and K_z. The occultations of Koskinen et al (2015) give K_z with an accuracy that has never been possible before and the combination of occultations and airglow therefore provide estimates of the mixing ratio in the lower atmosphere. We make these estimates at several locations that can be reasonably studied with both occultations and airglow and then average the results. Our results lead to a greatly improved estimate of the mixing ratio of He in the upper atmosphere and below. The second objective is to constrain the dynamics in the atmosphere by using the estimate of the He mixing ratio from the main objective. Once we have an estimate of the He mixing ratio in the lower atmosphere that agrees with both occultations and airglow, helium becomes an effective tracer species as any variations in the Cassini UVIS helium data are direct indicator of changes in K_z i.e., dynamics. Our third objective is to connect this work to our Cassini UVIS data He 584 Å airglow analyses as they both cover the time span of the observations and allow us to monitor changes in the airglow observations that may correlate with changes in the state of the atmosphere as revealed by the occultations Saturn's upper thermosphere. This work helps to determine the

  15. Numerical Survey of Self-gravity Wakes in Saturn's Rings

    Science.gov (United States)

    Salo, H.

    Although the total mass of Saturn's rings is small compared to the central mass, the mutual gravity between ring particles has a crucial role in shaping the local ring structure. In essence, the rings are on the verge of gravitational instability, due to their low velocity dispersion resulting from the dissipative physical impacts between particles. In differentially rotating rings this near-instability manifests in the form of tilted shearing density enhancements, as demonstrated by various N-body simulations (e.g Salo 1992, Nature 359, 619). Autocorrelation analysis indicates that these structures are analogous to the transient wakes produced by an orbiting body in a self-gravitating stellar disk (Julian and Toomre 1966, ApJ 146, 810). The term 'gravity wakes' is thus very appropriate, emphasizing the fact that these structures are a superposition of numerous individual Julian-Toomre wakes excited around each and every ring particle. The crucial difference to stellar disks is that in planetary rings the collisional dissipation balances the strong gravitational heating induced by the wakes themselves. This enables a statistical steady-state with a constant average wake amplitude and pitch angle, characterized by a continuous dissolution and regeneration of individual wakes in time scales ˜ orbital period. I will report some results of an ongoing N-body survey of wake structures in systems of different geometrical optical depth and the strength of self-gravity (related to the distance and the internal density of particles). Also factors like particle elasticity and the role of size distribution are examined. An essential part of this survey is the combination of dynamical and photometric modeling (see Salo et al. 2004, Icarus 170, 70), connecting the N-body density structures to directly observable quantities, like the photometric optical depth and the brightness of rings in reflected and transmitted light, when viewed from different orientations with respect to

  16. Shallow water simulations of Saturn's giant storms at different latitudes

    Science.gov (United States)

    García-Melendo, E.; Sánchez-Lavega, A.

    2017-04-01

    Shallow water simulations are used to present a unified study of three major storms on Saturn (nicknamed as Great White Spots, GWS) at different latitudes, polar (1960), equatorial (1990), and mid-latitude (2010) (Sánchez-Lavega, 2004; Sánchez-Lavega et al., 2011). In our model, the three GWS are initiated by introducing a Gaussian function pulse at the latitude of the observed phenomena with controlled horizontal size and amplitude. This function represents the convective source that has been observed to trigger the storm. A growing disturbance forms when the pulse reacts to ambient winds, expanding zonally along the latitude band of the considered domain. We then compare the modeled potential vorticity with the cloud field, adjusting the model parameters to visually get the closest aspect between simulations and observations. Simulations of the 2010 GWS (planetographic latitude ∼+40º, zonal velocity of the source ∼-30 m s-1) indicate that the Coriolis forces and the wind profile structure shape the disturbance generating, as observed, a long region to the east of the convective source with a high speed peripheral anticyclonic circulation, and a long-lived anticyclonic compact vortex accompanied by strong zonal advection on the southern part of the storm forming a turbulent region. Simulations of the equatorial 1990 GWS (planetographic latitude +12º-+5º, zonal velocity of the source 365-400 m s-1) show a different behavior because of the intense eastward jet, meridional shear at the equatorial region, and low latitude dynamics. A round shaped source forms as observed, with the rapid growth of a Kelvin-Helmholtz instability on the north side of the source due to advection and to the strong meridional wind shear, whereas at the storm latitude the disturbance grows and propagates eastward. The storm nucleus is the manifestation of a Rossby wave, while the eastward propagating planetary-scale disturbance is a gravity-Rossby wave trapped around the equator

  17. Habitability potential of satellites around Jupiter and Saturn

    Science.gov (United States)

    Coustenis, Athena; Raulin, Francois; Encrenaz, Therese; Grasset, Olivier; Solomonidou, Anezina

    2016-07-01

    In looking for habitable conditions in the outer solar system recent research focuses on the natural satellites rather than the planets themselves. Indeed, the habitable zone as traditionally defined may be larger than originally conceived. The outer solar system satellites provide a conceptual basis within which new theories for understanding habitability can be constructed. Measurements from the ground but also by the Voyager, Galileo and the Cassini spacecrafts revealed the potential of these satellites in this context, and our understanding of habitability in the solar system and beyond can be greatly enhanced by investigating several of these bodies together [1]. Their environments seem to satisfy many of the "classical" criteria for habitability (liquid water, energy sources to sustain metabolism and chemical compounds that can be used as nutrients over a period of time long enough to allow the development of life). Indeed, several of the moons show promising conditions for habitability and the development and/or maintenance of life. The strong gravitational pull caused by the giant planets may produce enough energy to sufficiently heat the cores of orbiting icy moons. Europa and Ganymede may be hiding, under their icy crust, putative undersurface liquid water oceans [2] which, in the case of Europa [3], may be in direct contact with a silicate mantle floor and kept warm by tidally generated heat [4]. Titan and Enceladus, Saturn's satellites, were found by the Cassini-Huygens mission to possess active organic chemistries with seasonal variations, unique geological features and possibly internal liquid water oceans. Titan's rigid crust and the probable existence of a subsurface ocean create an analogy with terrestrial-type plate tectonics, at least surficial [5], while Enceladus' plumes find an analogue in geysers. As revealed by Cassini the liquid hydrocarbon lakes [6] distributed mainly at polar latitudes on Titan are ideal isolated environments to look for

  18. Selection of a common communication link geometry for Saturn, Uranus and Titan. [mission planning for Pioneer and Mariner space probes

    Science.gov (United States)

    Hendricks, T.

    1974-01-01

    Mission analysis link parametrics, considering a Pioneer baseline, are developed through launch energies, flyby radii, and trip time calculations. Projected is also a 1979 Jupiter Uranus opportunity for a derivative Mariner to fly to Uranus by using the gravity field of Jupiter.

  19. An employee sews thermal insulation material on the back cover and heat shield of the Huygens probe

    Science.gov (United States)

    1997-01-01

    An employee in the Payload Hazardous Servicing Facility (PHSF) sews thermal insulation material on the back cover and heat shield of the Huygens probe during prelaunch processing, testing and integration in that facility. The Huygens probe and the Cassini orbiter being processed at KSC are the two primary components of the Cassini spacecraft, which will be launched on a Titan IVB/Centaur expendable launch vehicle from Cape Canaveral Air Station. Cassini will explore Saturn, its rings and moons for four years. The Huygens probe, designed and developed for the European Space Agency (ESA), will be deployed from the orbiter to study the clouds, atmosphere and surface of Saturn's largest moon, Titan. The orbiter was designed and assembled at NASA's Jet Propulsion Laboratory in California. Following postflight inspections, integration of the 12 science instruments not already installed on the orbiter will be completed. Then, the parabolic high-gain antenna and the propulsion module will be mated to the orbiter, followed by the Huygens probe, which will complete spacecraft integration. The Cassini mission is targeted for an Oct. 6 launch to begin its 6.7-year journey to the Saturnian system. Arrival at the planet is expected to occur around July 1, 2004.

  20. VG2 LECP 3.2 MINUTE SATURN FAR ENCOUNTER STEP DATA

    Data.gov (United States)

    National Aeronautics and Space Administration — Voyager 2 Energetic Particle (LECP) data from the Saturn far encounter period between 1981-08-29T06:30:47 and 1981-09-01T06:30:54. The data set provides 3.2 minute...

  1. Analysis of Saturn's Thermal Emission at 2.2-cm Wavelength: Spatial Distribution of Ammonia Vapor

    Science.gov (United States)

    Laraia, A. L.; Ingersoll, A. P.; Janssen, Michael A.; Gulkis, Samuel; Oyafuso, Fabiano A.; Allison, Michael D.

    2013-01-01

    This work focuses on determining the latitudinal structure of ammonia vapor in Saturn's cloud layer near 1.5 bars using the brightness temperature maps derived from the Cassini RADAR (Elachi et al., 2004) instrument, which works in a passive mode to measure thermal emission from Saturn at 2.2-cm wavelength. We perform an analysis of five brightness temperature maps that span epochs from 2005 to 2011, which are presented in a companion paper by Janssen et al. (2013a, this issue). The brightness temperature maps are representative of the spatial distribution of ammonia vapor, since ammonia gas is the only effective opacity source in Saturn's atmosphere at 2.2-cm wavelength. Relatively high brightness temperatures indicate relatively low ammonia relative humidity (RH), and vice versa. We compare the observed brightness temperatures to brightness temperatures computed using the Juno atmospheric microwave radiative transfer (JAMRT) program which includes both the means to calculate a tropospheric atmosphere model for Saturn and the means to carry out radiative transfer calculations at microwave frequencies. The reference atmosphere to which we compare has a 3x solar deep mixing ratio of ammonia (we use 1.352x10(exp -4) for the solar mixing ratio of ammonia vapor relative to H2; see Atreya, 2010) and is fully saturated above its cloud base. The maps are comprised of residual brightness temperatures-observed brightness temperature minus the model brightness temperature of the saturated atmosphere.

  2. Loss of Water from Saturn's E-Ring Through Ion Pick-Up

    Science.gov (United States)

    Leisner, J. S.; Russell, C. T.; Dougherty, M. K.; Blanco-Cano, X.; Smith, E. J.; Tsurutani, B. T.

    2005-01-01

    One of the possible loss processes for Saturn s E-ring is ionization followed by acceleration by the electric field associated with the corotating magnetized plasma. It is possible to determine if this process is occurring by detecting electromagnetic waves at the gyrofrequency of water group ions. If the energy the particle gains in this pick-up process is sufficiently great, the picked up ions will generate ion cyclotron waves. Pioneer 11 and Voyager 1 both observed intervals of such waves associated with water group ions during their passes through Saturn s E-ring. Presently the magnetometer onboard the Cassini spacecraft is also seeing water group ion cyclotron oscillations. The Cassini data allow the spatial and temporal behavior of the waves to be mapped in ways not possible during the previous flybys. Analyses of these waves allow us to study the rate of mass loading and its latitudinal and local time variation. In conjunction with previous data, we can then determine the variation as the inclination of the ring to the Sun changes, in accordance with Saturn's seasons. These waves may be the clue to how Saturn powers its magnetosphere as the newly born ions could be the driver for the radial motion of the plasma and to how the E-ring may play the equivalent role to that of Io in the jovian magnetosphere.

  3. The End of Cassini: Final VLBA Astrometry Epochs to Improve the Saturn Ephemeris

    Science.gov (United States)

    Jones, Dayton; Folkner, William M.; Romney, Jonathan D.; Dhawan, Vivek

    2018-01-01

    During the past dozen years we have used the Very Long Baseline Array (VLBA) to measure the position of the Cassini spacecraft in orbit around Saturn. These data, combined with fits of Cassini’s orbit with respect to Saturn from Deep Space Network tracking, have provided a time series of positions for the Saturn system barycenter in the inertial International Celestial Reference Frame (ICRF). We we report results from the final observing epochs of this program obtained prior to Cassini’s intentional destruction in the atmosphere of Saturn in September 2017. We now know Saturn’s orbit to approximately 0.2 mas (1 nrad), nearly two orders of magnitude better than it was know before the Cassini mission. Our VLBA positions provide the best constraints on the orientation of Saturn’s orbit (inclination and longitude of ascending node), while ranging data provide the best constraints on the orbit semi-major axis and eccentricity. This work has been partially supported by a grant from the NASA Planetary Astronomy program to the Space Science Institute, Boulder, CO. Part of this work has been carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The Long Baseline Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  4. Saturn's moon Phoebe as a captured body from the outer Solar System.

    Science.gov (United States)

    Johnson, Torrence V; Lunine, Jonathan I

    2005-05-05

    The orbital properties of Phoebe, one of Saturn's irregular moons, suggest that it was captured by the ringed planet's gravitational field rather than formed in situ. Phoebe's generally dark surface shows evidence of water ice, but otherwise the surface most closely resembles that of C-type asteroids and small outer Solar System bodies such as Chiron and Pholus that are thought to have originated in the Kuiper belt. A close fly-by of Phoebe by the Cassini-Huygens spacecraft on 11 June 2004 (19 days before the spacecraft entered orbit around Saturn) provided an opportunity to test the hypothesis that this moon did not form in situ during Saturn's formation, but is instead a product of the larger protoplanetary disk or 'solar nebula'. Here we derive the rock-to-ice ratio of Phoebe using its density combined with newly measured oxygen and carbon abundances in the solar photosphere. Phoebe's composition is close to that derived for other solar nebula bodies such as Triton and Pluto, but is very different from that of the regular satellites of Saturn, supporting Phoebe's origin as a captured body from the outer Solar System.

  5. How tides get dissipated in Saturn? A question probably answerable by Cassni

    Science.gov (United States)

    Luan, Jing

    2017-06-01

    Tidal dissipation inside a giant planet is important in understanding the orbital evolutions of its natural satellites and perhaps some of the extrasolar giant planets. The tidal dissipation is conventionally parameterized by the tidal quality factor, Q. The corresponding tidal torque declines rapidly with distance adopting constant Q. However, the current fast migration rates of some Saturnian satellites reported by Lainey et al. (2015) conflict this conventional conceptual belief. Alternatively, resonance lock between a satellite and an internal oscillation mode or wave of Saturn, proposed by Fuller et al. (2016), could naturally match the observational migration rates. However, the question still remains to be answered what type of mode or wave is locked with each satellite. There are two candidates for resonance lock, one is gravity mode, and the other is inertial wave attractor. They generate very different gravity acceleration anomaly near the surface of Saturn, which may be distinguishable by the data to be collected by Cassini during its proximal orbits between April and September, 2017. Indicative information about the interior of Saturn may be extracted since the existence of both gravity mode and inertial wave attractor depends on the internal structure of Saturn.

  6. The deuterium abundance in Jupiter and Saturn from ISO-SWS observations

    NARCIS (Netherlands)

    Lellouch, E; Bezard, B; Fouchet, T; Feuchtgruber, H; Encrenaz, T; de Graauw, T

    Observations with the Short Wavelength Spectrometer (SWS) onboard the Infrared Space Observatory (ISO) are used to determine the D/H ratio in Jupiter's and Saturn's atmospheres. The D/H ratio is measured independently in hydrogen (i.e. from the HD/H-2 ratio) and methane (from CH3D/CH4). Observations

  7. VizieR Online Data Catalog: MIR brightness contrast of Saturn's rings (Fujiwara+, 2017)

    Science.gov (United States)

    Fujiwara, H.; Morishima, R.; Fujiyoshi, T.; Yamashita, T.

    2016-11-01

    Brightness maps for Saturn's rings at 8.8, 9.7, 10.5, 11.7, 12.5, 17.7, 18.8, 20.5, and 24.5 micron observed with Subaru Telescope/COMICS in 2008 and at 12.5 and 24.5 micron in 2005 are provides as fits files. (2 data files).

  8. The dark side of Saturn's rings: Comparing eclipse observations from Cassini

    Science.gov (United States)

    Hedman, M. M.; Burns, J. A.; Porco, C.

    2013-12-01

    Three times over the past 7 years, Cassini has passed through Saturn's shadow and obtained spectacular mosaics of Saturn's rings backlit by the Sun. Beyond providing some of the most striking images from the mission, these observations yield unique information about Saturn's most tenuous rings, including the D, E and G rings. The small particles that dominate the optical cross section of these rings scatter light most efficiently in these backlit viewing geometries, so these eclipse events allow us to detect and characterize extremely faint ringlets that are nearly impossible to detect at any other time. For example, we can clearly see ringlets associated with several small moons like Pallene and Janus, which are likely composed of debris knock off these moons by meteoroid impacts. These eclipse observations also contain unique information about the large-scale structure of Saturn's E ring. This broad ring is derived from Enceladus' plume, but also exhibits puzzling longitudinal asymmetries in its brightness and color that are likely due to non-gravitational perturbations acting on the tiny ring particles. Differences among the eclipse observations from 2006, 2012 and 2013, which were obtained at different seasons and solar illumination conditions, should permit a better understanding the forces sculpting this ring.

  9. An Isolated, Bright Cusp Aurora Associated with Dayside Reconnection at Saturn

    Science.gov (United States)

    Kinrade, J.; Badman, S. V.; Arridge, C. S.; Tao, C.; Provan, G.; Dougherty, M. K.; Grocott, A.

    2016-12-01

    Saturn's dayside aurorae display a number of morphological features polewards of the main emission region. We present an unusual morphology captured by the Hubble Space Telescope on 14 June 2014, where, for two hours, Saturn's FUV aurorae disappeared almost entirely, with the exception of a distinct emission spot at high latitude. The spot remained fixed in local time between 11-15 LT, and moved polewards to a maximum latitude of 85°, close to the magnetic dipole and planetary rotation axis. It was bright and persistent, displaying intensities of up to 49 kR over a lifetime of two hours. The formation of the spot coincided with the decay of Saturn's characteristic dawn arc, the complete absence of which is rarely observed. Solar wind parameters from propagation models, together with a Cassini magnetopause crossing, indicated a period of rarefaction and an uncompressed magnetosphere. We infer that the spot was sustained by repeated reconnection either poleward of the cusp, or at low-latitudes under a strong transverse component in the IMF. The poleward motion could then arise from either reconfiguration of successive open field lines across the polar cap, or convection of newly opened field lines. We also consider the influence of planetary period modulation of the feature by rotating current systems. This case study poses interesting questions about the driving of Saturn's aurorae ahead of the upcoming proximal Cassini orbits.

  10. Solar System Exploration Augmented by In-Situ Resource Utilization: Mercury and Saturn Propulsion Investigations

    Science.gov (United States)

    Palaszewski, Bryan

    2016-01-01

    Human and robotic missions to Mercury and Saturn are presented and analyzed with a range of propulsion options. Historical studies of space exploration, in-situ resource utilization (ISRU), and industrialization all point to the vastness of natural resources in the solar system. Advanced propulsion benefitted from these resources in many ways. While advanced propulsion systems were proposed in these historical studies, further investigation of nuclear options using high power nuclear thermal and nuclear pulse propulsion as well as advanced chemical propulsion can significantly enhance these scenarios. Updated analyses based on these historical visions will be presented. Nuclear thermal propulsion and ISRU enhanced chemical propulsion landers are assessed for Mercury missions. At Saturn, nuclear pulse propulsion with alternate propellant feed systems and Titan exploration with chemical propulsion options are discussed. In-situ resource utilization was found to be critical in making Mercury missions more amenable for human visits. At Saturn, refueling using local atmospheric mining was found to be difficult to impractical, while refueling the Saturn missions from Uranus was more practical and less complex.

  11. Foldable polymers as probes

    Science.gov (United States)

    Li, Alexander D. Q.; Wang, Wei

    2007-07-03

    Disclosed herein are novel probes, which can be used to detect and identify target molecules of interest in a sample. The disclosed probes can be used to monitor conformational changes induced by molecular recognition events in addition to providing signaling the presence and/or identity of a target molecule. Methods, including solid phase synthesis techniques, for making probe molecules that exhibit changes in their optical properties upon target molecule binding are described in the disclosure. Also disclosed herein are novel chromophore moieties, which have tailored fluorescent emission spectra.

  12. Origin of Saturn's rings and inner moons by mass removal from a lost Titan-sized satellite.

    Science.gov (United States)

    Canup, Robin M

    2010-12-16

    The origin of Saturn's rings has not been adequately explained. The current rings are more than 90 to 95 per cent water ice, which implies that initially they were almost pure ice because they are continually polluted by rocky meteoroids. In contrast, a half-rock, half-ice mixture (similar to the composition of many of the satellites in the outer Solar System) would generally be expected. Previous ring origin theories invoke the collisional disruption of a small moon, or the tidal disruption of a comet during a close passage by Saturn. These models are improbable and/or struggle to account for basic properties of the rings, including their icy composition. Saturn has only one large satellite, Titan, whereas Jupiter has four large satellites; additional large satellites probably existed originally but were lost as they spiralled into Saturn. Here I report numerical simulations of the tidal removal of mass from a differentiated, Titan-sized satellite as it migrates inward towards Saturn. Planetary tidal forces preferentially strip material from the satellite's outer icy layers, while its rocky core remains intact and is lost to collision with the planet. The result is a pure ice ring much more massive than Saturn's current rings. As the ring evolves, its mass decreases and icy moons are spawned from its outer edge with estimated masses consistent with Saturn's ice-rich moons interior to and including Tethys.

  13. STRONG TIDAL DISSIPATION IN SATURN AND CONSTRAINTS ON ENCELADUS' THERMAL STATE FROM ASTROMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Lainey, Valery; Desmars, Josselin; Arlot, Jean-Eudes; Emelyanov, Nicolai; Remus, Francoise [IMCCE-Observatoire de Paris, UMR 8028 du CNRS, UPMC, 77 Av. Denfert-Rochereau, 75014 Paris (France); Karatekin, Oezguer [Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Uccle, Bruxelles (Belgium); Charnoz, Sebastien; Mathis, Stephane [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/SAp Centre de Saclay, 91191 Gif-sur-Yvette (France); Le Poncin-Lafitte, Christophe [SyRTE-Observatoire de Paris, UMR 8630 du CNRS, 77 Av. Denfert-Rochereau, 75014 Paris (France); Tobie, Gabriel [Laboratoire de Planetologie et Geodynamique de Nantes, Universite de Nantes, CNRS, UMR 6112, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Zahn, Jean-Paul, E-mail: lainey@imcce.fr [LUTH-Observatoire de Paris, UMR 8102 du CNRS, 5 place Jules Janssen, 92195 Meudon Cedex (France)

    2012-06-10

    Tidal interactions between Saturn and its satellites play a crucial role in both the orbital migration of the satellites and the heating of their interiors. Therefore, constraining the tidal dissipation of Saturn (here the ratio k{sub 2}/Q) opens the door to the past evolution of the whole system. If Saturn's tidal ratio can be determined at different frequencies, it may also be possible to constrain the giant planet's interior structure, which is still uncertain. Here, we try to determine Saturn's tidal ratio through its current effect on the orbits of the main moons, using astrometric data spanning more than a century. We find an intense tidal dissipation (k{sub 2}/Q = (2.3 {+-} 0.7) Multiplication-Sign 10{sup -4}), which is about 10 times higher than the usual value estimated from theoretical arguments. As a consequence, eccentricity equilibrium for Enceladus can now account for the huge heat emitted from Enceladus' south pole. Moreover, the measured k{sub 2}/Q is found to be poorly sensitive to the tidal frequency, on the short frequency interval considered. This suggests that Saturn's dissipation may not be controlled by turbulent friction in the fluid envelope as commonly believed. If correct, the large tidal expansion of the moon orbits due to this strong Saturnian dissipation would be inconsistent with the moon formations 4.5 Byr ago above the synchronous orbit in the Saturnian subnebulae. But it would be compatible with a new model of satellite formation in which the Saturnian satellites formed possibly over a longer timescale at the outer edge of the main rings. In an attempt to take into account possible significant torques exerted by the rings on Mimas, we fitted a constant rate da/dt on Mimas' semi-major axis as well. We obtained an unexpected large acceleration related to a negative value of da/dt = -(15.7 {+-} 4.4) Multiplication-Sign 10{sup -15} AU day{sup -1}. Such acceleration is about an order of magnitude larger

  14. The membrane fusion step of vaccinia virus entry is cooperatively mediated by multiple viral proteins and host cell components.

    Directory of Open Access Journals (Sweden)

    Jason P Laliberte

    2011-12-01

    Full Text Available For many viruses, one or two proteins allow cell attachment and entry, which occurs through the plasma membrane or following endocytosis at low pH. In contrast, vaccinia virus (VACV enters cells by both neutral and low pH routes; four proteins mediate cell attachment and twelve that are associated in a membrane complex and conserved in all poxviruses are dedicated to entry. The aim of the present study was to determine the roles of cellular and viral proteins in initial stages of entry, specifically fusion of the membranes of the mature virion and cell. For analysis of the role of cellular components, we used well characterized inhibitors and measured binding of a recombinant VACV virion containing Gaussia luciferase fused to a core protein; viral and cellular membrane lipid mixing with a self-quenching fluorescent probe in the virion membrane; and core entry with a recombinant VACV expressing firefly luciferase and electron microscopy. We determined that inhibitors of tyrosine protein kinases, dynamin GTPase and actin dynamics had little effect on binding of virions to cells but impaired membrane fusion, whereas partial cholesterol depletion and inhibitors of endosomal acidification and membrane blebbing had a severe effect at the later stage of core entry. To determine the role of viral proteins, virions lacking individual membrane components were purified from cells infected with members of a panel of ten conditional-lethal inducible mutants. Each of the entry protein-deficient virions had severely reduced infectivity and except for A28, L1 and L5 greatly impaired membrane fusion. In addition, a potent neutralizing L1 monoclonal antibody blocked entry at a post-membrane lipid-mixing step. Taken together, these results suggested a 2-step entry model and implicated an unprecedented number of viral proteins and cellular components involved in signaling and actin rearrangement for initiation of virus-cell membrane fusion during poxvirus entry.

  15. Galactically inertial space probes for the direct measurement of the metric expansion of the universe

    Energy Technology Data Exchange (ETDEWEB)

    Cagnani, Ivan, E-mail: ivan@omgl.org [Physics student, University of Bologna, Istituto di Fisica, via Irnerio 46, 40126, Bologna (Italy)

    2011-02-01

    Astrometric data from the future GAIA and OBSS missions will allow a more precise calculation of the local galactic circular speed, and better measurements of galactic movements relative to the CMB will be obtained by post-WMAP missions (ie Planck). Contemporary development of high specific impulse electric propulsion systems (ie VASIMIR) will enable the development of space probes able to properly compensate the galactic circular speed as well as the resulting attraction to the centre of our galaxy. The probes would appear immobile to an ideal observer fixed at the centre of the galaxy, in contrast of every other galactic object, which would appear moving according to their local galactic circular speed and their proper motions. Arranging at least three of these galactically static probes in an extended formation and measuring reciprocal distances of the probes over time with large angle laser ranges could allow a direct measurement of the metric expansion of the universe. Free-drifting laser-ranged targets released by the spacecrafts could also be used to measure and compensate solar system's induced local perturbations. For further reducing local effects and increase the accuracy of the results, the distance between the probes should be maximized and the location of the probes should be as far as possible from the Sun and any massive object (ie Jupiter, Saturn). Gravitational waves could also induce random errors but data from GW observatories like the planned LISA could be used to correct them.

  16. A Long-lived Cyclone In Saturn's Atmosphere: Observations And Models

    Science.gov (United States)

    Del Rio Gaztelurrutia, Teresa; Legarreta, J.; Hueso, R.; Pérez-Hoyos, S.; Sánchez-Lavega, A.

    2009-09-01

    The atmospheres of the Giant Planets Jupiter and Saturn possess large numbers of atmospheric vortices. On Jupiter, anticyclones are generally long-lived structures while cyclones survive a much shorter time. A long term survey of images of Saturn atmosphere obtained by the Cassini ISS camera has revealed the presence of a long-lived cyclone in Saturn's southern hemisphere during at least four years, making this vortex the longest lived cyclone on either Jupiter or Saturn. We find that the vortex drifts following the wind profile, with changes in velocity following changes of latitude. During the four years of our survey its size remained essentially constant, and there was no other structure of comparable size at its latitude. Internal circulation is cyclonic, with a maximum velocity of 20±5 m/s and an average vorticity of 4·10-5 s-1, an order of magnitude lower than planetary vorticity, but only slightly higher than the ambient vorticity. Photometric analysis shows that the vortex is located at a slightly lower altitude than its surroundings, at an average of 10-20 mbar below adjacent clouds. Finally, EPIC simulations of the vortex that reproduce its behavior imply a Rossby deformation radius of 2000 km in the weather layer (1 - 10 bar), consistent with the size of the cyclone. The long-lifetime of this cyclonic spot is surprising in view of its low tangential velocity and it suggests that low dissipation conditions prevail at mid-latitudes in Saturn's upper troposphere. Acknowledgements This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07. RH acknowledges a "Ramón y Cajal” contract from MEC.

  17. A possible influence of the Great White Spot on Saturn kilometric radiation periodicity

    Directory of Open Access Journals (Sweden)

    G. Fischer

    2014-12-01

    Full Text Available The periodicity of Saturn kilometric radiation (SKR varies with time, and its two periods during the first 5 years of the Cassini mission have been attributed to SKR from the northern and southern hemisphere. After Saturn equinox in August 2009, there were long intervals of time (March 2010 to February 2011 and September 2011 to June 2012 with similar northern and southern SKR periods and locked SKR phases. However, from March to August 2011 the SKR periods were split up again, and the phases were unlocked. In this time interval, the southern SKR period slowed down by ~ 0.5% on average, and there was a large jump back to a faster period in August 2011. The northern SKR period speeded up and coalesced again with the southern period in September 2011. We argue that this unusual behavior could be related to the so-called Great White Spot (GWS, a giant thunderstorm that raged in Saturn's atmosphere around that time. For several months in 2011, the visible head of the GWS had the same period of ~ 10.69 h as the main southern SKR modulation signal. The GWS was most likely a source of intense gravity waves that may have caused a global change in Saturn's thermospheric winds via energy and momentum deposition. This would support the theory that Saturn's magnetospheric periodicities are driven by the upper atmosphere. Since the GWS with simultaneous SKR periodicity measurements have only been made once, it is difficult to prove a physical connection between these two phenomena, but we provide plausible mechanisms by which the GWS might modify the SKR periods.

  18. Effect of hot injections on electromagnetic ion-cyclotron waves in inner magnetosphere of Saturn

    Science.gov (United States)

    Kumari, Jyoti; Kaur, Rajbir; Pandey, R. S.

    2018-02-01

    Encounter of Voyager with Saturn's environment revealed the presence of electromagnetic ion-cyclotron waves (EMIC) in Saturnian magnetosphere. Cassini provided the evidence of dynamic particle injections in inner magnetosphere of Saturn. Also inner magnetosphere of Saturn has highest rotational flow shear as compared to any other planet in our solar system. Hence during these injections, electrons and ions are transported to regions of stronger magnetic field, thus gaining energy. The dynamics of the inner magnetosphere of Saturn are governed by wave-particle interaction. In present paper we have investigated those EMIC waves pertaining in background plasma which propagates obliquely with respect to the magnetic field of Saturn. Applying kinetic approach, the expression for dispersion relation and growth rate has been derived. Magnetic field model has been used to incorporate magnetic field strength at different latitudes for radial distance of 6.18 R_{{s}} (1 R_{{s}}= 60{,}268 km). Various parameters affecting the growth of EMIC waves in cold bi-Maxwellian background and after the hot injections has been studied. Parametric analysis inferred that after hot injections, growth rate of EMIC waves increases till 10° and decreases eventually with increase in latitude due to ion density distribution in near-equatorial region. Also, growth rate of EMIC waves increases with increasing value of temperature anisotropy and AC frequency, but the growth rate decreases as the angle of propagation with respect to B0 (Magnetic field at equator) increases. The injection events which assume the Loss-cone distribution of particles, affect the lower wave numbers of the spectra.

  19. Innermost Van Allen Radiation Belt for High Energy Protons at Saturn

    Science.gov (United States)

    Cooper, John F.

    2008-01-01

    The high energy proton radiation belts of Saturn are energetically dominated by the source from cosmic ray albedo neutron decay (CRAND), trapping of protons from beta decay of neutrons emitted from galactic cosmic ray nuclear interactions with the main rings. These belts were originally discovered in wide gaps between the A-ring, Janus/Epimetheus, Mimas, and Enceladus. The narrow F and G rings significant affected the CRAND protons but did not produce total depletion. Voyager 2 measurements subsequently revealed an outermost CRAND proton belt beyond Enceladus. Although the source rate is small, the trapping times limited by radial magnetospheric diffusion are very long, about ten years at peak measured flux inwards of the G ring, so large fluxes can accumulate unless otherwise limited in the trapping region by neutral gas, dust, and ring body interactions. One proposed final extension of the Cassini Orbiter mission would place perikrone in a 3000-km gap between the inner D ring and the upper atmosphere of Saturn. Experience with CRAND in the Earth's inner Van Allen proton belt suggests that a similar innermost belt might be found in this comparably wide region at Saturn. Radial dependence of magnetospheric diffusion, proximity to the ring neutron source, and northward magnetic offset of Saturn's magnetic equator from the ring plane could potentially produce peak fluxes several orders of magnitude higher than previously measured outside the main rings. Even brief passes through such an intense environment of highly penetrating protons would be a significant concern for spacecraft operations and science observations. Actual fluxes are limited by losses in Saturn's exospheric gas and in a dust environment likely comparable to that of the known CRAND proton belts. The first numerical model of this unexplored radiation belt is presented to determine limits on peak magnitude and radial profile of the proton flux distribution.

  20. Hard probes 2006 Asilomar

    CERN Multimedia

    2006-01-01

    "The second international conference on hard and electromagnetic probes of high-energy nuclear collisions was held June 9 to 16, 2006 at the Asilomar Conference grounds in Pacific Grove, California" (photo and 1/2 page)

  1. Financial Performance of Entry Mode Decisions

    DEFF Research Database (Denmark)

    Boyd, Britta; Dyhr Ulrich, Anna Marie; Hollensen, Svend

    2012-01-01

    Based on a survey of 170 Danish SMEs the paper examines influences on entry mode choices and the financial outcome of these decisions. The main research objectives are divided into two steps: Step 1: To determine the factors influencing the choice of foreign entry modes by Danish companies. Step ...... and implications are provided for companies willing to invest more into foreign markets in order to achieve a higher degree of control and better financial results.......Based on a survey of 170 Danish SMEs the paper examines influences on entry mode choices and the financial outcome of these decisions. The main research objectives are divided into two steps: Step 1: To determine the factors influencing the choice of foreign entry modes by Danish companies. Step 2......: To determine the relationship between the choice of entry mode and export performance, measured in terms of financial outcome. Drawing from transaction cost theory the authors develop and test a model where different factors affect the level of control chosen by the parent company. This study contributes...

  2. Atmospheric Entry Studies for Venus Missions: 45 Sphere-Cone Rigid Aeroshells and Ballistic Entries

    Science.gov (United States)

    Prabhu, Dinesh K.; Spilker, Thomas R.; Allen, Gary A., Jr.; Hwang, Helen H.; Cappuccio, Gelsomina; Moses, Robert W.

    2013-01-01

    The present study considers direct ballistic entries into the atmosphere of Venus using a 45deg sphere-cone rigid aeroshell, a legacy shape that has been used successfully in the past in the Pioneer Venus Multiprobe Mission. For a number of entry mass and heatshield diameter combinations (i.e., various ballistic coefficients) and entry velocities, the trajectory space in terms of entry flight path angles between skip out and -30deg is explored with a 3DoF trajectory code, TRAJ. From these trajectories, the viable entry flight path angle space is determined through the use of mechanical and thermal performance limits on the thermal protection material and science payload; the thermal protection material of choice is entry-grade carbon phenolic, for which a material thermal response model is available. For mechanical performance, a 200 g limit is placed on the peak deceleration load experienced by the science instruments, and 10 bar is assumed as the pressure limit for entry-grade carbon-phenolic material. For thermal performance, inflection points in the total heat load distribution are used as cut off criteria. Analysis of the results shows the existence of a range of critical ballistic coefficients beyond which the steepest possible entries are determined by the pressure limit of the material rather than the deceleration load limit.

  3. A close look at Saturn's rings with Cassini VIMS

    Science.gov (United States)

    Nicholson, P.D.; Hedman, M.M.; Clark, R.N.; Showalter, M.R.; Cruikshank, D.P.; Cuzzi, J.N.; Filacchione, G.; Capaccioni, F.; Cerroni, P.; Hansen, G.B.; Sicardy, B.; Drossart, P.; Brown, R.H.; Buratti, B.J.; Baines, K.H.; Coradini, A.

    2008-01-01

    Soon after the Cassini-Huygens spacecraft entered orbit about Saturn on 1 July 2004, its Visual and Infrared Mapping Spectrometer obtained two continuous spectral scans across the rings, covering the wavelength range 0.35-5.1 ??m, at a spatial resolution of 15-25 km. The first scan covers the outer C and inner B rings, while the second covers the Cassini Division and the entire A ring. Comparisons of the VIMS radial reflectance profile at 1.08 ??m with similar profiles at a wavelength of 0.45 ??m assembled from Voyager images show very little change in ring structure over the intervening 24 years, with the exception of a few features already known to be noncircular. A model for single-scattering by a classical, many-particle-thick slab of material with normal optical depths derived from the Voyager photopolarimeter stellar occultation is found to provide an excellent fit to the observed VIMS reflectance profiles for the C ring and Cassini Division, and an acceptable fit for the inner B ring. The A ring deviates significantly from such a model, consistent with previous suggestions that this region may be closer to a monolayer. An additional complication here is the azimuthally-variable average optical depth associated with "self-gravity wakes" in this region and the fact that much of the A ring may be a mixture of almost opaque wakes and relatively transparent interwake zones. Consistently with previous studies, we find that the near-infrared spectra of all main ring regions are dominated by water ice, with a typical regolith grain radius of 5-20 ??m, while the steep decrease in visual reflectance shortward of 0.6 ??m is suggestive of an organic contaminant, perhaps tholin-like. Although no materials other than H2O ice have been identified with any certainty in the VIMS spectra of the rings, significant radial variations are seen in the strength of the water-ice absorption bands. Across the boundary between the C and B rings, over a radial range of ???7000 km, the

  4. Enabling Code_Saturne for Multi-Petaflop/Exascale with MPI 3.0 one sided Communication

    OpenAIRE

    Chandan Basu

    2014-01-01

    Code_Saturne is a popular open-source computational fluid dynamics package. We have carried out a study of applying MPI 2.0 / MPI 3.0 one sided communication routines to Code_Saturne and its impact on improving the scalability of the code for future peta/exa-scaling. We have developed modified versions of the halo exchange routine in Code_Saturne. Our modifications showed that MPI 2.0 one sided calls give some speed improvement and less memory overhead compared to the original ver...

  5. Regulation of Entry and the Distortion of Industrial Organization

    OpenAIRE

    Raymond Fisman; Virginia Sarria-Allende

    2004-01-01

    We study the distortions to industrial organization caused by entry regulation. We take advantage of heterogeneity across industries in their natural barriers and growth opportunities to examine whether some industries are differentially affected by country-level entry regulation. In industries with high natural entry barriers, entry regulation has little impact on the quantity and average size of firms in an industry. By contrast, in industries with low natural entry barriers, countries with...

  6. 19 CFR 141.56 - Single entry summary for multiple transportation entries consigned to the same consignee.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Single entry summary for multiple transportation entries consigned to the same consignee. 141.56 Section 141.56 Customs Duties U.S. CUSTOMS AND BORDER... transportation entries consigned to the same consignee. (a) Requirement. Port directors may accept one entry...

  7. Flow Redistribution Between Legs and Brain During STS 93 Re-Entry and Landing

    Science.gov (United States)

    Arbeille, P.; Meck, J.; Porcher, M.; Benavides, E.; Martin, D. S.; South, D. A.; Ribeiro, C.; Westover, A.

    2003-01-01

    The objective was to quantify bit by bit the arterial hemodynamic response to the successive acceleration induced fluid shifts during re-entry and landing. Method: The astronaut instrumented himself with a flat Doppler probe fixed on the skin, a blood pressure arm cuff, and 3 ECG electrodes. The ICMS (integrated cardiovascular monitoring system, 15x15x25 cu cm, battery powered) designed to monitor Blood pressure, ECG, cerebral and femoral flows was fixed below the astronaut sit in the middeck. Recordings started 5 minutes before de-orbiting (TIG) and stopped 5 min after wheels stop. Results. During re-entry blood pressure increased by 20% at TIG, and then by 25 to 30% during the highest Gz accelerations (approx 1 S g ) . The cerebral flow remained decreased by 10 to 15% below inflight value all during the Entry and landing phases. Conversely the femoral flow increased at TIG and entry ( + l0 to 20%), recovered at 0.lg, and then decreased in proportion with the Gz acceleration (-10% to -40% from 0.5g to 1.5g). The reduction in Femoral flow was associated with an opposite variation in lower limb vascular resistance. Consequently the cerebral flow/femoral flow ratio decreased at TIG and entry (-20%), and then increased according to the Gz acceleration level ( + l0 to +40% from 0.5 to 1.5g). Conclusion: During orthostatic tests (Stand LBNP tests) the cerebral to femoral flow ratio allowed to quantify the efficiency of the flow redistribution between these 2 areas and predicted orthostatic intolerance. In the present case the astronaut was found orthostatically tolerant at postflight tilt tests, but we suggest that during re-entry this parameter could predict the occurrence of syncope in severely disadapted astronauts.

  8. Modes and orders of market entry

    DEFF Research Database (Denmark)

    Ulhøi, John Parm

    2012-01-01

    This paper focuses on the initial questions of how and when to enter a market from the perspective of a firm. By entry mode is meant a firm’s strategy (innovation or imitation) for entering the market in response to environmental changes. Entry order refers to the related issue of market timing...... strategies are more ambiguous. Based on a corporate technology and innovation strategy perspective, the paper reconceptualises and extends existing modes and orders of market entry, and in particular clarifies the ambiguity associated with imitative strategies. Four distinct imitator strategies...... are identified. The paper closes with a brief discussion of limitations, avenues for future research, and implications for managers and affected policymakers....

  9. Form, its meaning, and dictionary entries

    Directory of Open Access Journals (Sweden)

    Violetta Koseska-Toszewa

    2015-11-01

    It is worth stressing that distinguishing between the form and its meaning in comparing the material 6 languages belonging to three different groups of Slavic languages (as is the case in the MONDILEX Project will allow us to avoid numeorus substantiva mistakes and erroneous conclusions. Hence dictionary entries should be verified and made uniform in that respect before they are “digitalized”... Distinction between the form and its meaning in a dictionary entry is fully possible, as shown by works of Z. Saloni (2002 and A.Przepiórkowski (2008.

  10. Nonsulfated, cinnamic acid-based lignins are potent antagonists of HSV-1 entry into cells.

    Science.gov (United States)

    Thakkar, Jay N; Tiwari, Vaibhav; Desai, Umesh R

    2010-05-10

    In an effort to discover macromolecular mimetics of heparan sulfate (HS), we previously designed sulfated lignins (Raghuraman et al. Biomacromolecules 2007, 8, 1759-1763). To probe the relevance of sulfate groups of HS in viral entry, lignins completely devoid of sulfate moieties, and yet possessing an electrostatic surface equivalent to that of HS, were designed. Two carboxylated lignins based on a 4-hydroxy cinnamic acid scaffold were synthesized using enzymatic oxidative coupling in high yields, fractionated according to their sizes, and tested in cellular assays of herpes simplex virus-1 (HSV-1) infection. The two carboxylated lignins were found to not only inhibit HSV-1 entry into mammalian cells (IC(50) = 8-56 nM), but were more potent than sulfated lignins. In addition, shorter carboxylated lignins were found to be as active as the longer chains, suggesting that structural features, in addition to carboxylate groups, may be important. It can be expected that carboxylated lignins also antagonize the entry of other enveloped viruses, for example, HIV-1, Kaposi's sarcoma-associated herpes virus, and hepatitis C virus, that utilize HS to gain entry into cells. The results present major opportunities for developing lignin-based antiviral formulations for topical use.

  11. Characteristics of the overflow pollution of storm drains with inappropriate sewage entry.

    Science.gov (United States)

    Yin, Hailong; Lu, Yi; Xu, Zuxin; Li, Huaizheng; Schwegler, Benedict R

    2017-02-01

    To probe the overflow pollution of separate storm drains with inappropriate sewage entries, in terms of the relationship between sewage entries and the corresponding dry-weather and wet-weather overflow, the monitoring activities were conducted in a storm drainage system in the Shanghai downtown area (374 ha). In this study site, samples from inappropriately entered dry-weather sewage and the overflow due to storm pumps operation on dry-weather and wet-weather days were collected and then monitored for six water quality constituents. It was found that overflow concentrations of dry-weather period could be higher than those of wet-weather period; under wet-weather period, the overflow concentrations of storm drains were close to or even higher than that of combined sewers. Relatively strong first flush mostly occurred under heavy rain that satisfied critical rainfall amount, maximum rainfall intensity, and maximum pumping discharge, while almost no first flush effect or only weak first flush effect was found for the other rainfall events. Such phenomenon was attributed to lower in-line pipe storage as compared to that of the combined sewers, and serious sediment accumulation within the storm pipes due to sewage entry. For this kind of system, treating a continuous overflow rate is a better strategy than treating the maximum amount of early part of the overflow. Correcting the key inappropriate sewage entries into storm drains should also be focused.

  12. Model for resonant plasma probe.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue

    2007-04-01

    This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.

  13. The Cassini Reaction Wheels: Drag and Spin-Rate Trends from an Aging Interplanetary Spacecraft at Saturn

    Science.gov (United States)

    Brown, Todd S.

    2016-01-01

    The purpose of this paper is to provide a summary of the long-term trends of the estimated drag torque and spin-rates of the Cassini reaction wheel assemblies during eleven years of intensive science operations at Saturn..

  14. Synergism of Saturn, Enceladus and Titan and Formation of HCNO Prebiotic Molecules

    Science.gov (United States)

    Sittler, Edward C.; Cooper, John F.

    2011-01-01

    Saturn as a system has two very exotic moons Titan and Enceladus. Titan, taking in energy from Saturn's magnetosphere, solar UV irradiation, and cosmic rays, can make HCN based molecules as discussed in earlier paper by Raulin and Owen. Space radiation effects at both moons, and as coupled by the Saturn magnetosphere, could cause an unexpected series of events potentially leading to prebiotic chemical evolution at Titan with HCNO from magnetospheric oxygen as the new ingredient. The "Old Faithful" model suggests that Enceladus, highly irradiated by Saturn magnetospheric electrons and thus having a source of chemical energy from radiolytic gas production, has episodic ejections of water vapor, carbon dioxide, and various hydrocarbons into Saturn's magnetosphere. The hydrocarbons do not survive transport through the plasma environment, but oxygen ions from Enceladus water molecules become the dominant ion species in the outer magnetosphere. At Titan, Cassini discovered that 1) keV oxygen ions, evidently from Enceladus, are bombarding Titan's upper atmosphere and 2) heavy positive and negative ions exist in significant abundances within Titan's upper atmosphere. Initial models of heavy ion formation in Titan's upper atmosphere invoked polymerization of aromatics such as benzenes and their radicals to make polycyclic aromatic hydrocarbons (PAH) , while a more recent model by Sittler et al., has raised the possibility of carbon chains forming from the polymerization of acetylene and its radicals to make fullerenes. Laboratory measurements indicate that fullerenes, which are hollow carbon shells, can trap keV oxygen ions. Clustering of the fullerenes with aerosol mixtures from PAHs and the dominant nitrogen molecules could form larger aerosols enriched in trapped oxygen. Aerosol precipitation could then convey these chemically complex structures deeper into the atmosphere and to the moon surface. Ionizing solar UV, magnetospheric electron, and galactic cosmic ray

  15. PAHs in the Ices of Saturn's Satellites: Connections to the Solar Nebula and the Interstellar Medium

    Science.gov (United States)

    Cruikshank, Dale P.; Pendleton, Yvonne J.

    2015-01-01

    Aliphatic hydrocarbons and PAHs have been observed in the interstellar medium (e.g., Allamandola et al. 1985, Pendleton et al. 1994, Pendleton & Allamandola 2002, Tielens 2013, Kwok 2008, Chiar & Pendleton 2008) The inventory of organic material in the ISM was likely incorporated into the molecular cloud in which the solar nebula condensed, contributing to the feedstock for the formation of the Sun, major planets, and the smaller icy bodies in the region outside Neptune's orbit (transneptunian objects, or TNOs). Additional organic synthesis occurred in the solar nebula (Ciesla & Sandford 2012). Saturn's satellites Phoebe, Iapetus, and Hyperion open a window to the composition of one class of TNO as revealed by the near-infrared mapping spectrometer (VIMS) on the Cassini spacecraft at Saturn. Phoebe (mean diameter 213 km) is a former TNO now orbiting Saturn (Johnson & Lunine 2005). VIMS spectral maps of Phoebe's surface reveal a complex organic spectral signature consisting of prominent aromatic (CH) and aliphatic hydrocarbon (=CH2, -CH3) absorption bands (3.2-3.6 micrometers). Phoebe is the source of a huge debris ring encircling Saturn, and from which particles ((is) approximately 5-20 micrometers size) spiral inward toward Saturn (Verbiscer et al. 2009). They encounter Iapetus and Hyperion where they mix with and blanket the native H2O ice of those two bodies. Quantitative analysis of the hydrocarbon bands on Iapetus demonstrates that aromatic CH is approximately 10 times as abundant as aliphatic CH2+CH3, significantly exceeding the strength of the aromatic signature in interplanetary dust particles, comet particles, and in carbonaceous meteorites (Cruikshank et al. 2014). A similar excess of aromatics over aliphatics is seen in the qualitative analysis of Hyperion and Phoebe itself (Dalle Ore et al. 2012). The Iapetus aliphatic hydrocarbons show CH2/CH3 (is) approximately 4, which is larger than the value found in the diffuse ISM ((is) approximately 2

  16. A statistical analysis of the location and width of Saturn's southern auroras

    Directory of Open Access Journals (Sweden)

    S. V. Badman

    2006-12-01

    Full Text Available A selection of twenty-two Hubble Space Telescope images of Saturn's ultraviolet auroras obtained during 1997–2004 has been analysed to determine the median location and width of the auroral oval, and their variability. Limitations of coverage restrict the analysis to the southern hemisphere, and to local times from the post-midnight sector to just past dusk, via dawn and noon. It is found that the overall median location of the poleward and equatorward boundaries of the oval with respect to the southern pole are at ~14° and ~16° co-latitude, respectively, with a median latitudinal width of ~2°. These median values vary only modestly with local time around the oval, though the poleward boundary moves closer to the pole near noon (~12.5° such that the oval is wider in that sector (median width ~3.5° than it is at both dawn and dusk (~1.5°. It is also shown that the position of the auroral boundaries at Saturn are extremely variable, the poleward boundary being located between 2° and 20° co-latitude, and the equatorward boundary between 6° and 23°, this variability contrasting sharply with the essentially fixed location of the main oval at Jupiter. Comparison with Voyager plasma angular velocity data mapped magnetically from the equatorial magnetosphere into the southern ionosphere indicates that the dayside aurora lie poleward of the main upward-directed field-aligned current region associated with corotation enforcement, which maps to ~20°–24° co-latitude, while agreeing reasonably with the position of the open-closed field line boundary based on estimates of the open flux in Saturn's tail, located between ~11° and ~15°. In this case, the variability in location can be understood in terms of changes in the open flux present in the system, the changes implied by the Saturn data then matching those observed at Earth as fractions of the total planetary flux. We infer that the broad (few degrees diffuse auroral emissions

  17. The mass of Saturn's B-ring from Cassini's Grand Finale orbits

    Science.gov (United States)

    Racioppa, Paolo; Durante, Daniele; Iess, Luciano

    2017-04-01

    Cassini is one of the most successful space missions of all times. Arrived at Saturn in 2004, it collected an enormous amount of scientific data on the atmosphere and the magnetosphere of the gas giant, its icy moons, and its rings. In the final part of journey, ending in a deliberate plunge into Saturn's atmosphere, the spacecraft will collect gravity and magnetic data from a distance as close as 3000 km from the cloud level. Those data are crucial to build interior models of the planet and to determine the depth of zonal winds. The Cassini radio science investigation will measure Saturn gravity field and the ring mass by means of range rate measurements enabled by the onboard X band (7.2-8.4 GHz) radio system and the antennas of NASA's Deep Space Network and ESA's tracking network. The gravity determination is obtained by fitting the radial velocity of the spacecraft at accuracies of about 0.05 mm/s (at a time scale of 60 s) through predictions obtained from a model of the orbital dynamics. Cassini orbital geometry is crucial for the gravity experiment. The highly eccentric 6-day orbit has a pericenter close to Saturn's clouds, within the inner edge of the rings. With Cassini passing between the rings and the planet, there is an excellent prospect to disentangle the strong acceleration due to Saturn's oblateness from that due to tiny pull of the rings. The mass of the rings (concentrated mostly in the B ring) remains uncertain. Its value, generally expressed in terms of Mimas masses, bears crucial information on how and when the rings formed, and their relation with Saturn and its moons. This work presents the final round of simulations of the gravity experiment in Cassini's Grand Finale orbits, using the latest trajectory, spacecraft configuration, and tracking coverage from ground. In particular, we will provide our current best estimate of the accuracy in the ring mass determination, just a few months prior to the actual measurements taking place in six orbits

  18. The infinite line pressure probe

    Science.gov (United States)

    Englund, D. R.; Richards, W. B.

    1985-01-01

    The infinite line pressure probe provides a means for measuring high frequency fluctuating pressures in difficult environments. A properly designed infinite line probe does not resonate; thus its frequency response is not limited by acoustic resonance in the probe tubing, as in conventional probes. The characteristics of infinite line pressure probes are reviewed and some applications in turbine engine research are described. A probe with a flat-oval cross section, permitting a constant-impedance pressure transducer installation, is described. Techniques for predicting the frequency response of probes with both circular and flat-oval cross sections are also cited.

  19. Multidisciplinary Tool for Systems Analysis of Planetary Entry, Descent, and Landing

    Science.gov (United States)

    Samareh, Jamshid A.

    2011-01-01

    Systems analysis of a planetary entry (SAPE), descent, and landing (EDL) is a multidisciplinary activity in nature. SAPE improves the performance of the systems analysis team by automating and streamlining the process, and this improvement can reduce the errors that stem from manual data transfer among discipline experts. SAPE is a multidisciplinary tool for systems analysis of planetary EDL for Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Titan. It performs EDL systems analysis for any planet, operates cross-platform (i.e., Windows, Mac, and Linux operating systems), uses existing software components and open-source software to avoid software licensing issues, performs low-fidelity systems analysis in one hour on a computer that is comparable to an average laptop, and keeps discipline experts in the analysis loop. SAPE uses Python, a platform-independent, open-source language, for integration and for the user interface. Development has relied heavily on the object-oriented programming capabilities that are available in Python. Modules are provided to interface with commercial and government off-the-shelf software components (e.g., thermal protection systems and finite-element analysis). SAPE currently includes the following analysis modules: geometry, trajectory, aerodynamics, aerothermal, thermal protection system, and interface for structural sizing.

  20. Continuous Aerodynamic Modelling of Entry Shapes

    NARCIS (Netherlands)

    Dirkx, D.; Mooij, E.

    2011-01-01

    During the conceptual design phase of a re-entry vehicle, the vehicle shape can be varied and its impact on performance evaluated. To this end, the continuous modeling of the aerodynamic characteristics as a function of the shape is useful in exploring the full design space. Local inclination

  1. Female entrepreneurial networks and foreign market entry

    DEFF Research Database (Denmark)

    Rosenbaum, Gitte Ohrt

    2017-01-01

    The purpose of this paper is to explore the role of networks in the 116 foreign market entries (FMEs) of women-owned small businesses. A multiple case study based on semi-structured interviews with eight female entrepreneurs in the Danish fashion design industry. The results show that contrary...

  2. Thinking and Reading for Entry Level Workers.

    Science.gov (United States)

    Allentown Literacy Council, PA.

    A pilot project demonstrated that cooperative training programs are effective and cost efficient for small businesses. Common entry-level reading and thinking tasks were identified in a variety of occupational areas. Five growing occupational areas were identified: industrial/machine operator; health care; food preparation; hotel/hospitality; and…

  3. Entry modes of European firms in Vietnam

    Directory of Open Access Journals (Sweden)

    Daniel Simonet

    2012-09-01

    Full Text Available Purpose: The purpose of the paper is to explore the entry modes of EU firms setting up operations in Vietnam. Design/methodology/approach: we use a case study approach on Haymarket, Cadbury, Creative Education, Fairchild, Aventis and Artemisinin and Farming International using interviews from managerial professionals in Vietnam. Findings: Despite the fact that Vietnam has been opening up for more than 20 years, licensing is the preferred entry mode because of the risks involved in venturing with local firms; that preference signals a low level commitment and a high perception of risk and state interference. In line with Vietnam transition to state - rather than private market - capitalism, a foreign company opting for a joint-venture will do so with a state-owned rather than privately-owned company. The choice of a subsidiary can be explained by the lack of trust in partners and institutions, not by improvement in the socio-political environment. Limitations: In determining the entry mode strategy, the paper focuses on the Uppsala school’s “psychic distance” (e.g. cultural distance, lack of trust rather than on firm-specific advantages (Rugman, 1980; 2006. Key-words: international entry mode; emerging markets; subsidiary; joint-venture; India; Vietnam

  4. Internet portals as portfolios of entry options

    NARCIS (Netherlands)

    Perotti, E.C.; Rossetto, S.

    2000-01-01

    We investigate the valuation of platform investment, such as a software operating system or an Internet portal WebPage. Platform investment is the creation of an innovative distribution and production infrastructure, which increases access to customers; as a result it reduces entry costs in related

  5. Flavivirus cell entry and membrane fusion

    NARCIS (Netherlands)

    Smit, Jolanda M.; Moesker, Bastiaan; Rodenhuis-Zybert, Izabela; Wilschut, Jan

    Flaviviruses, such as dengue virus and West Nile virus, are enveloped viruses that infect cells through receptor-mediated endocytosis and fusion from within acidic endosomes. The cell entry process of flaviviruses is mediated by the viral E glycoprotein. This short review will address recent

  6. Radiation and critical shocks in atmospheric entry

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1997-12-01

    Sub- and supercritical shock waves are produced during atmospheric entry. The radiation efficiency of the former increases strongly with velocity and altitude; that of the latter increases with altitude, but decreases with supercritical velocities. These efficiencies shift the region of maximum radiation one to two scale heights higher and decrease overall radiation efficiency.

  7. Flavivirus cell entry and membrane fusion

    NARCIS (Netherlands)

    Smit, Jolanda M.; Moesker, Bastiaan; Rodenhuis-Zybert, Izabela; Wilschut, Jan

    2011-01-01

    Flaviviruses, such as dengue virus and West Nile virus, are enveloped viruses that infect cells through receptor-mediated endocytosis and fusion from within acidic endosomes. The cell entry process of flaviviruses is mediated by the viral E glycoprotein. This short review will address recent

  8. Correlation Between Entry Requirements and Academic ...

    African Journals Online (AJOL)

    In this study, the investigator examines the correlation between entry requirements and academic performance of undergraduate students at the University of Buea. The quality of performance on the Cameroon General Certificate Examination at the Advanced Level is the predictor while the criterion is the cumulative grade ...

  9. Foreign entry, cultural barriers and learning

    NARCIS (Netherlands)

    H.G. Barkema (Harry); J.H.J. Bell (John); J.M.E. Pennings

    1996-01-01

    textabstractThis paper examines the longevity of foreign entries. Hypotheses are developed on the mode (start-ups vs. acquisitions) and ownership structure (wholly owned vs. joint ventures) in relation to cultural distance. The hypotheses are tested within a framework of organizational learning,

  10. 19 CFR 159.7 - Rewarehouse entries.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Rewarehouse entries. 159.7 Section 159.7 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY.... When any of the following types of merchandise are withdrawn from warehouse for transportation to...

  11. Business entry and window of opportunity

    DEFF Research Database (Denmark)

    Tegtmeier, Silke; Kurczewska, Agnieszka

    2017-01-01

    This paper explores the nascence period - the time between idea generation and business entry -among women entrepreneurs with a graduate degree. To address this research problem and to better understand the specifics of a window of opportunity, we combine selected theories of human and social...

  12. Shuttle Entry Imaging Using Infrared Thermography

    Science.gov (United States)

    Horvath, Thomas; Berry, Scott; Alter, Stephen; Blanchard, Robert; Schwartz, Richard; Ross, Martin; Tack, Steve

    2007-01-01

    During the Columbia Accident Investigation, imaging teams supporting debris shedding analysis were hampered by poor entry image quality and the general lack of information on optical signatures associated with a nominal Shuttle entry. After the accident, recommendations were made to NASA management to develop and maintain a state-of-the-art imagery database for Shuttle engineering performance assessments and to improve entry imaging capability to support anomaly and contingency analysis during a mission. As a result, the Space Shuttle Program sponsored an observation campaign to qualitatively characterize a nominal Shuttle entry over the widest possible Mach number range. The initial objectives focused on an assessment of capability to identify/resolve debris liberated from the Shuttle during entry, characterization of potential anomalous events associated with RCS jet firings and unusual phenomenon associated with the plasma trail. The aeroheating technical community viewed the Space Shuttle Program sponsored activity as an opportunity to influence the observation objectives and incrementally demonstrate key elements of a quantitative spatially resolved temperature measurement capability over a series of flights. One long-term desire of the Shuttle engineering community is to calibrate boundary layer transition prediction methodologies that are presently part of the Shuttle damage assessment process using flight data provided by a controlled Shuttle flight experiment. Quantitative global imaging may offer a complementary method of data collection to more traditional methods such as surface thermocouples. This paper reviews the process used by the engineering community to influence data collection methods and analysis of global infrared images of the Shuttle obtained during hypersonic entry. Emphasis is placed upon airborne imaging assets sponsored by the Shuttle program during Return to Flight. Visual and IR entry imagery were obtained with available airborne

  13. IMF dependence of Saturn's auroras: modelling study of HST and Cassini data from 12–15 February 2008

    Directory of Open Access Journals (Sweden)

    E. S. Belenkaya

    2010-08-01

    Full Text Available To gain better understanding of auroral processes in Saturn's magnetosphere, we compare ultraviolet (UV auroral images obtained by the Hubble Space Telescope (HST with the position of the open-closed field line boundary in the ionosphere calculated using a magnetic field model that employs Cassini measurements of the interplanetary magnetic field (IMF as input. Following earlier related studies of pre-orbit insertion data from January 2004 when Cassini was located ~ 1300 Saturn radii away from the planet, here we investigate the interval 12–15 February 2008, when UV images of Saturn's southern dayside aurora were obtained by the HST while the Cassini spacecraft measured the IMF in the solar wind just upstream of the dayside bow shock. This configuration thus provides an opportunity, unique to date, to determine the IMF impinging on Saturn's magnetosphere during imaging observations, without the need to take account of extended and uncertain interplanetary propagation delays. The paraboloid model of Saturn's magnetosphere is then employed to calculate the magnetospheric magnetic field structure and ionospheric open-closed field line boundary for averaged IMF vectors that correspond, with appropriate response delays, to four HST images. We show that the IMF-dependent open field region calculated from the model agrees reasonably well with the area lying poleward of the UV emissions, thus supporting the view that the poleward boundary of Saturn's auroral oval in the dayside ionosphere lies adjacent to the open-closed field line boundary.

  14. Coronaviruses induce entry-independent, continuous macropinocytosis.

    Science.gov (United States)

    Freeman, Megan Culler; Peek, Christopher T; Becker, Michelle M; Smith, Everett Clinton; Denison, Mark R

    2014-08-05

    Macropinocytosis is exploited by many pathogens for entry into cells. Coronaviruses (CoVs) such as severe acute respiratory syndrome (SARS) CoV and Middle East respiratory syndrome CoV are important human pathogens; however, macropinocytosis during CoV infection has not been investigated. We demonstrate that the CoVs SARS CoV and murine hepatitis virus (MHV) induce macropinocytosis, which occurs late during infection, is continuous, and is not associated with virus entry. MHV-induced macropinocytosis results in vesicle internalization, as well as extended filopodia capable of fusing with distant cells. MHV-induced macropinocytosis requires fusogenic spike protein on the cell surface and is dependent on epidermal growth factor receptor activation. Inhibition of macropinocytosis reduces supernatant viral titers and syncytia but not intracellular virus titers. These results indicate that macropinocytosis likely facilitates CoV infection through enhanced cell-to-cell spreading. Our studies are the first to demonstrate virus use of macropinocytosis for a role other than entry and suggest a much broader potential exploitation of macropinocytosis in virus replication and host interactions. Importance: Coronaviruses (CoVs), including severe acute respiratory syndrome (SARS) CoV and Middle East respiratory syndrome CoV, are critical emerging human pathogens. Macropinocytosis is induced by many pathogens to enter host cells, but other functions for macropinocytosis in virus replication are unknown. In this work, we show that CoVs induce a macropinocytosis late in infection that is continuous, independent from cell entry, and associated with increased virus titers and cell fusion. Murine hepatitis virus macropinocytosis requires a fusogenic virus spike protein and signals through the epidermal growth factor receptor and the classical macropinocytosis pathway. These studies demonstrate CoV induction of macropinocytosis for a purpose other than entry and indicate that viruses

  15. Sex-related differences of coronary atherosclerosis regression following maximally intensive statin therapy: insights from SATURN.

    Science.gov (United States)

    Puri, Rishi; Nissen, Steven E; Shao, Mingyuan; Ballantyne, Christie M; Barter, Phillip J; Chapman, M John; Erbel, Raimund; Libby, Peter; Raichlen, Joel S; Uno, Kiyoko; Kataoka, Yu; Nicholls, Stephen J

    2014-10-01

    The study sought to explore sex-related differences in coronary atheroma regression following high-intensity statin therapy. Guidelines now recommend high-intensity statins in all individuals with atherosclerotic cardiovascular disease. SATURN (Study of Coronary Atheroma by Intravascular Ultrasound: Effect of Rosuvastatin Versus Atorvastatin) employed serial intravascular ultrasound measures of coronary atheroma volume in patients treated with rosuvastatin 40 mg or atorvastatin 80 mg for 24 months. The treatment groups did not differ significantly in change from baseline of percent atheroma volume (PAV) or total atheroma volume (TAV) on intravascular ultrasound, nor in safety or clinical outcomes. Compared with men (n = 765), women (n = 274) were older (p SATURN]; NCT000620542). Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  16. Comparative magnetotail flapping: an overview of selected events at Earth, Jupiter and Saturn

    Directory of Open Access Journals (Sweden)

    M. Volwerk

    2013-05-01

    Full Text Available A comparison of magnetotail flapping (the up-and-down wavy motion between the Earth and the two giant planets Jupiter and Saturn has been performed through investigation of the current sheet normal of the magnetotail. Magnetotail flapping is commonly observed in the Earth's magnetotail. Due to single spacecraft missions at the giant planets, the normal is determined through minimum variance analysis of magnetometer data during multiple intervals when the spacecraft crossed through the current sheet. It is shown that indeed a case can be made that magnetotail flapping also occurs at Jupiter and Saturn. Calculations of the wave period using generic magnetotail models show that the observed periods are much shorter than their theoretical estimates, and that this discrepancy can be caused by unknown input parameters for the tail models (e.g., current sheet thickness and by possible Doppler shifting of the waves in the spacecraft frame through the fast rotation of the giant planets.

  17. Perturbations to Saturn's F-ring strands at their closest approach to Prometheus

    Science.gov (United States)

    Giuliatti, Winter S.M.; Murray, C.D.; Gordon, M.

    2000-01-01

    The strange morphology of the F ring of Saturn is thought to be caused by the perturbing effects of two close satellites, Prometheus and Pandora. The F ring and the satellites also experience periodic close encounters as a result of differential precession arising from Saturn's oblateness. Using the orbits of the F-ring strands derived by Murray et al. (1997, Icarus 129, 304-316) the behaviour of the ring particles at their closest approach to Prometheus is analysed using numerical simulations. The results show that a gap and a wave are formed in the ring at each encounter with the satellite. However, the gap is expected to have a short lifetime due to keplerian shear. ?? 2000 Elsevier Science Ltd. All rights reserved.

  18. On what we have learned about the system of Saturn thanks to Cassini

    Science.gov (United States)

    El Moutamid, Maryame; Hedman, Matthew M.; Nicholson, Philip D.; Tiscareno, Matthew S.; Tajeddine, Radwan; Burns, Joseph A.

    2017-06-01

    This is the end; Cassini will crash into Saturn’s atmosphere within few months, providing unique data and results thanks to the last orbits. After losing contact with us, it will become part of the planet itself.By September 2017, Cassini will have spent 13 years in orbit around Saturn, during this period, scientists from the world have collected data from many instruments and have learned a great deal about the planet itself, its rings and satellites, and the connection between them. I will present some of the results on what we have learned about the evolution of the moons, on the main rings of Saturn and their dynamical connection with the interior of the planet.

  19. Gravitational vortices and clump formation in Saturn's F ring during an encounter with Prometheus.

    Science.gov (United States)

    Sutton, Phil J; Kusmartsev, Feodor V

    2013-01-01

    Saturn rings are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-ring have been attributed to encounters by Prometheus on the F ring, with investigations of optical thickness revealing large populations of transient moonlets. Taking into account gravitational interaction between particles and a multi-stranded F-ring structure we show that Prometheus' encounters create rotational flows, like atmospheric vortices and the self-gravity enhances the accelerated growth and size of moonlets. Vortex patches form caustics, which is a primary cause of the transient particle density clumps of 20 km width and 100 km length, and they are elongated to cover an area of 1600 km by 150 km, which may eventually combine into a vortex sheet.

  20. The Titan -1:0 Nodal Bending Wave in Saturn's Ring C.

    Science.gov (United States)

    Rosen, P A; Lissauer, J J

    1988-08-05

    The most prominent oscillatory feature observed in the Voyager 1 radio occultation of Saturn's rings is identified as a one-armed spiral bending wave excited by Titan's -1:0 nodal inner vertical resonance. Ring partides in a bending wave move in coherently inclined orbits, warping the local mean plane of the rings. The Titan -1:0 wave is the only known bending wave that propagates outward, away from Saturn, and the only spiral wave yet observed in which the wave pattern rotates opposite to the orbital direction of the ring particles. It is also the first bending wave identified in ring C. Modeling the observed feature with existing bending wave theory gives a surface mass density of approximately 0.4 g/cm(2) outside the wave region and a local ring thickness of [unknown]5 meters, and suggests that surface mass density is not constant in the wave region.

  1. Cassini Orbit Trim Maneuvers at Saturn - Overview of Attitude Control Flight Operations

    Science.gov (United States)

    Burk, Thomas A.

    2011-01-01

    The Cassini spacecraft has been in orbit around Saturn since July 1, 2004. To remain on the planned trajectory which maximizes science data return, Cassini must perform orbit trim maneuvers using either its main engine or its reaction control system thrusters. Over 200 maneuvers have been executed on the spacecraft since arrival at Saturn. To improve performance and maintain spacecraft health, changes have been made in maneuver design command placement, in accelerometer scale factor, and in the pre-aim vector used to align the engine gimbal actuator prior to main engine burn ignition. These and other changes have improved maneuver performance execution errors significantly since 2004. A strategy has been developed to decide whether a main engine maneuver should be performed, or whether the maneuver can be executed using the reaction control system.

  2. Saturn's South Polar Vortex: A Possible Gas-Giant Analog to a Terrestrial Hurricane

    Science.gov (United States)

    Dyudina, Ulyana A.; Ingersoll, A. P.; Ewald, S. P.; Vasavada, A. R.; West, R. A.; Del Genio, A.; Barbara, J.; Porco, C. C.; Porco, C. C.; Achterberg, R. K.; Flasar, F. M.; Simon-Miller, A. A.; Fletcher, L. N.

    2007-10-01

    Observations made by the Cassini spacecraft reveal a large, long-lived vortex anchored to the south pole of Saturn that shares many properties with terrestrial hurricanes. Among these are: a central eye with cyclonic vorticity, an outer region where vorticity is near zero, a warm temperature anomaly within the eye, concentric eyewall clouds that extend two pressure scale heights above the clouds within the eye, numerous small clouds whose anticyclonic vorticity suggests a convective origin, and evidence, at high altitudes, of excess cyclonic rotation not balanced by the inward pressure force, implying outward flow. Besides differences of scale, the main distinctions between hurricanes on Earth and the one seen on Saturn are the static, polar location of the latter and the lack of a liquid ocean to support it. This is the first hurricane-like vortex detected on a planet other than Earth.

  3. Cassini Returns to Saturn's Poles: Seasonal Change in the Polar Vortices

    Science.gov (United States)

    Fletcher, Leigh N.; Orton, G. S.; Irwin, P. G. J.; Sinclair, J. A.; Hesman, B. E.; Hurley, J.; Bjoraker, G. L.; Simon-Miller, A. A.

    2013-01-01

    High inclination orbits during Cassini's solstice mission (2012) are providing us with our first observations of Saturn's high latitudes since the prime mission (2007). Since that time, the northern spring pole has emerged into sunlight and the southern autumn pole has disappeared into winter darkness, allowing us to study the seasonal changes occurring within the polar vortices in response to these dramatic insolation changes. Observations from the Cassini Composite Infrared Spectrometer] have revealed (i) the continued presence of small, cyclonic polar hotspots at both spring and autumn poles; and (ii) the emergence of an infrared-bright polar vortex at the north pole, consistent with the historical record of Saturn observations from the 1980s (previous northern spring).

  4. Cassini finds an oxygen-carbon dioxide atmosphere at Saturn's icy moon Rhea.

    Science.gov (United States)

    Teolis, B D; Jones, G H; Miles, P F; Tokar, R L; Magee, B A; Waite, J H; Roussos, E; Young, D T; Crary, F J; Coates, A J; Johnson, R E; Tseng, W-L; Baragiola, R A

    2010-12-24

    The flyby measurements of the Cassini spacecraft at Saturn's moon Rhea reveal a tenuous oxygen (O(2))-carbon dioxide (CO(2)) atmosphere. The atmosphere appears to be sustained by chemical decomposition of the surface water ice under irradiation from Saturn's magnetospheric plasma. This in situ detection of an oxidizing atmosphere is consistent with remote observations of other icy bodies, such as Jupiter's moons Europa and Ganymede, and suggestive of a reservoir of radiolytic O(2) locked within Rhea's ice. The presence of CO(2) suggests radiolysis reactions between surface oxidants and organics or sputtering and/or outgassing of CO(2) endogenic to Rhea's ice. Observations of outflowing positive and negative ions give evidence for pickup ionization as a major atmospheric loss mechanism.

  5. Cassini Imaging Science: initial results on Saturn's rings and small satellites.

    Science.gov (United States)

    Porco, C C; Baker, E; Barbara, J; Beurle, K; Brahic, A; Burns, J A; Charnoz, S; Cooper, N; Dawson, D D; Del Genio, A D; Denk, T; Dones, L; Dyudina, U; Evans, M W; Giese, B; Grazier, K; Helfenstein, P; Ingersoll, A P; Jacobson, R A; Johnson, T V; McEwen, A; Murray, C D; Neukum, G; Owen, W M; Perry, J; Roatsch, T; Spitale, J; Squyres, S; Thomas, P; Tiscareno, M; Turtle, E; Vasavada, A R; Veverka, J; Wagner, R; West, R

    2005-02-25

    Images acquired of Saturn's rings and small moons by the Cassini Imaging Science Subsystem (ISS) during the first 9 months of Cassini operations at Saturn have produced many new findings. These include new saturnian moons; refined orbits of new and previously known moons; narrow diffuse rings in the F-ring region and embedded in gaps within the main rings; exceptionally fine-scale ring structure in moderate- to high-optical depth regions; new estimates for the masses of ring-region moons, as well as ring particle properties in the Cassini division, derived from the analysis of linear density waves; ring particle albedos in select ring regions; and never-before-seen phenomena within the rings.

  6. Exploring overstabilities in Saturn's a ring using two stellar occultations

    Energy Technology Data Exchange (ETDEWEB)

    Hedman, M. M. [Department of Physics, University of Idaho, Moscow, ID 83844 (United States); Nicholson, P. D. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Salo, H., E-mail: mhedman@uidaho.edu [Department of Physics, University of Oulu, Oulu (Finland)

    2014-07-01

    Certain regions of Saturn's rings exhibit periodic opacity variations with characteristic radial wavelengths of up to a few hundred meters that have been attributed to viscous overstabilities. The Visual and Infrared Mapping Spectrometer on board the Cassini spacecraft observed two stellar occultations of the star γ Crucis that had sufficient resolution to discern a subset of these periodic patterns in a portion of the A ring between 124,000 and 125,000 km from Saturn's center. These data reveal that the wavelengths and intensities of the patterns vary systematically across this region, but that these parameters are not strictly determined by the ring's average optical depth. Furthermore, our observations indicate that these opacity variations have an azimuthal coherence scale of around 3000 km.

  7. Astrometry of Cassini with the VLBA to improve the Saturn ephemeris

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Dayton L.; Folkner, William M.; Jacobson, Robert A.; Jacobs, Christopher S. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Dhawan, Vivek; Romney, Jon [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); Fomalont, Ed, E-mail: dayton.jones@jpl.nasa.gov [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)

    2015-01-01

    Planetary ephemerides have been developed and improved over centuries. They are a fundamental tool for understanding solar system dynamics, and essential for planetary and small body mass determinations, occultation predictions, high-precision tests of general relativity, pulsar timing, and interplanetary spacecraft navigation. This paper presents recent results from a continuing program of high-precision astrometric very long baseline interferometry (VLBI) observations of the Cassini spacecraft orbiting Saturn, using the Very Long Baseline Array (VLBA). We have previously shown that VLBA measurements can be combined with spacecraft orbit determinations from Doppler and range tracking and VLBI links to the inertial extragalactic reference frame to provide the most accurate barycentric positions currently available for Saturn. Here we report an additional five years of VLBA observations along with improved phase reference source positions, resulting in an improvement in residuals with respect to the Jet Propulsion Laboratory's dynamical ephemeris.

  8. Dynamic auroral storms on Saturn as observed by the Hubble Space Telescope.

    Science.gov (United States)

    Nichols, J D; Badman, S V; Baines, K H; Brown, R H; Bunce, E J; Clarke, J T; Cowley, S W H; Crary, F J; Dougherty, M K; Gérard, J-C; Grocott, A; Grodent, D; Kurth, W S; Melin, H; Mitchell, D G; Pryor, W R; Stallard, T S

    2014-05-28

    We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330% rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current.

  9. Solar System Exploration Augmented by In-Situ Resource Utilization: Human Mercury and Saturn Exploration

    Science.gov (United States)

    Palaszewski, Bryan

    2015-01-01

    Human and robotic missions to Mercury and Saturn are presented and analyzed. Unique elements of the local planetary environments are discussed and included in the analyses and assessments. Using historical studies of space exploration, in-situ resource utilization (ISRU), and industrialization all point to the vastness of natural resources in the solar system. Advanced propulsion benefitted from these resources in many way. While advanced propulsion systems were proposed in these historical studies, further investigation of nuclear options using high power nuclear thermal and nuclear pulse propulsion as well as advanced chemical propulsion can significantly enhance these scenarios. Updated analyses based on these historical visions will be presented. Nuclear thermal propulsion and ISRU enhanced chemical propulsion landers are assessed for Mercury missions. At Saturn, nuclear pulse propulsion with alternate propellant feed systems and Titan exploration with chemical propulsion options are discussed.

  10. NASA's Chandra Finds That Saturn Reflects X-rays From Sun

    Science.gov (United States)

    2005-05-01

    When it comes to mysterious X-rays from Saturn, the ringed planet may act as a mirror, reflecting explosive activity from the sun, according to scientists using NASA's Chandra X-ray Observatory. The findings stem from the first observation of an X-ray flare reflected from Saturn's low-latitudes - the region that correlates to Earth's equator and tropics. Led by Dr. Anil Bhardwaj, a planetary scientist at NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala., the study revealed that Saturn acts as a diffuse mirror for solar X-rays. Counting photons - particles that carry electromagnetic energy including X-rays - was critical to this discovery. For every few thousand X-ray photons Saturn receives from the sun, it reflects a single X-ray photon back. Previous studies revealed that Jupiter, with a diameter 11 times that of Earth, behaves in a similar fashion. Saturn is about 9.5 times as big as Earth, but is twice as far from Earth as Jupiter. "The bigger the planet and nearer to the Sun, the more solar photons it will intercept - resulting in more reflected X-rays," said Bhardwaj. "These results imply we could use giant planets like Jupiter and Saturn as remote-sensing tools. By reflecting solar activity back to us, they could help us monitor X-ray flaring on portions of the sun facing away from Earth's space satellites." Massive solar explosions called flares often accompany coronal mass ejections, which emit solar material and magnetic field. When directed toward the Earth, these ejections can wreak havoc on communication systems from cell phones to satellites. Even as the research appears to have solved one mystery - the source of Saturn's X-rays, it fueled longstanding questions about magnetic fields. Earth's magnetic field is the reason compasses work, since the field acts like a huge bar magnet, causing the magnetic north pole of a compass to point to the magnetic south pole of the Earth. In addition, migratory birds seem to sense the magnetic field

  11. Bremsstrahlung x ray spectra of Jupiter and Saturn: Predictions for future planetary spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, D.D. (Univ. of California, Los Angeles (USA))

    1990-07-01

    Calculations of X ray spectra due to bremsstrahlung from precipitating auroral electrons at Jupiter and Saturn are presented. The model assumes that a field-aligned potential drop accelerates a primary beam of electrons into the atmosphere where a population of secondary electrons having a power law energy dependence is generated. The spectrum at Jupiter is normalized to the soft X ray observations of Metzger et al (1983) at the low-energy end and constrained at the high-energy end by UV auroral energy requirements. The spectrum at Saturn is constructed by analogy to the Jovian case allowing for variation of the beam energy, energy flux, and scale size of the Saturnian aurora. The resulting indicate that a significant flux of X rays is emanating from both planets which may serve as a basis for conducting planetary X ray astronomy as part of future spacecraft missions to the planets.

  12. Characterization of Saturn's bow shock: Magnetic field observations of quasi-perpendicular shocks

    CERN Document Server

    Sulaiman, A H; Dougherty, M K

    2016-01-01

    Collisionless shocks vary drastically from terrestrial to astrophysical regimes resulting in radically different characteristics. This poses two complexities. Firstly, separating the influences of these parameters on physical mechanisms such as energy dissipation. Secondly, correlating observations of shock waves over a wide range of each parameter, enough to span across different regimes. Investigating the latter has been restricted since the majority of studies on shocks at exotic regimes (such as supernova remnants) have been achieved either remotely or via simulations, but rarely by means of in-situ observations. Here we present the parameter space of MA bow shock crossings from 2004-2014 as observed by the Cassini spacecraft. We find that Saturn's bow shock exhibits characteristics akin to both terrestrial and astrophysical regimes (MA of order 100), which is principally controlled by the upstream magnetic field strength. Moreover, we determined the {\\theta}Bn of each crossing to show that Saturn's (days...

  13. Performance analysis of large scale parallel CFD computing based on Code_Saturne

    Science.gov (United States)

    Shang, Zhi

    2013-02-01

    In order to run computational fluid dynamics (CFD) codes on large scales, parallel computing has to be employed. For instance, on Petascale computing, general parallel computing without any optimization is not enough, especially for complex industrial issues that employ a large number of mesh cells to capture the details of the geometry. How to distribute these mesh cells among the multi-processors for Terascale and Petascale systems to obtain a good performance on parallel computing is really a challenge. Some mesh partitioning software packages, such as Metis, ParMetis, PT-Scotch and Zoltan, were chosen as the candidates ported into Code_Saturne to test if they can lead Code_Saturne towards Petascale and Exascale parallel CFD computing. Through the studies, it was found that mesh partitioning optimization software packages based on the graph mesh partitioning method can help the CFD code obtain good mesh distributions for high performance computing (HPC).

  14. [An epidemiological survey on saturnism among children due to lead pollution released from township enterprise].

    Science.gov (United States)

    Li, Heng-xin; Song, Ya-li; Li, Hong-guang; Yuan, Yong-xin; Xu, Qing; Liu, En-xu; Li, Jin-song

    2008-03-01

    To understand the current situations of saturnism and blood lead levels of children resided in village and circumjacent areas, and to know its relations with sex, age and other factors on children' s health as to providing some evidences for prevention and control. An epidemiological survey was conducted for finding out the pollution sources and for a better understanding of the surrounding environment. All 221 children under 14 years old, from the lead pollution villages and surrounding establishments were enrolled, and their blood lead levels were detected by graphite atomizer absorption spectrophotometer method. Symptoms of the saturnism were investigated through a standardized questionnaire. SPSS13.0 software was administrated for data analysis. High blood lead level identification rate was 66.06% (146/221), and saturnism rate 32.13% (71/221). The children's blood lead levels among group 1, group 2, group 3 in this village and jade factory were (161.20 +/- 32.94), (176.60 +/- 43.62), (258.00 +/-106.08) and (238.01 +/- 55.20) microg/L respectively and the significant differences were observed through Kruskal-Wallis test (chi2 = 51.84, df= 3, Pfactory were higher than those of other two groups. No correlation was found between children's age and blood lead level (r = 0.10, P = 0.13). There was a significant difference in blood lead levels between boys and girls (t' = 3.83, P<0.01). With the children's blood lead levels rising, the occurrence rate of main saturnism symptoms was significantly increased. This survey suggested that the pollution source was a coarse lead smelter. The blood lead level should ke overwhelmingly increased among children who live nearby the higher level of lead blood, that living nearby the lead smeltery,might result in stautnism and negative effect on children's healthy.

  15. Disruption of Saturn's quasi-periodic equatorial oscillation by the great northern storm

    Science.gov (United States)

    Fletcher, Leigh N.; Guerlet, Sandrine; Orton, Glenn S.; Cosentino, Richard G.; Fouchet, Thierry; Irwin, Patrick G. J.; Li, Liming; Flasar, F. Michael; Gorius, Nicolas; Morales-Juberías, Raúl

    2017-11-01

    The equatorial middle atmospheres of the Earth1, Jupiter2 and Saturn3,4 all exhibit a remarkably similar phenomenon—a vertical, cyclic pattern of alternating temperatures and zonal (east-west) wind regimes that propagate slowly downwards with a well-defined multi-year period. Earth's quasi-biennial oscillation (QBO) (observed in the lower stratospheric winds with an average period of 28 months) is one of the most regular, repeatable cycles exhibited by our climate system1,5,6, and yet recent work has shown that this regularity can be disrupted by events occurring far away from the equatorial region, an example of a phenomenon known as atmospheric teleconnection7,8. Here, we reveal that Saturn's equatorial quasi-periodic oscillation (QPO) (with an 15-year period3,9) can also be dramatically perturbed. An intense springtime storm erupted at Saturn's northern mid-latitudes in December 201010-12, spawning a gigantic hot vortex in the stratosphere at 40° N that persisted for three years13. Far from the storm, the Cassini temperature measurements showed a dramatic 10 K cooling in the 0.5-5 mbar range across the entire equatorial region, disrupting the regular QPO pattern and significantly altering the middle-atmospheric wind structure, suggesting an injection of westward momentum into the equatorial wind system from waves generated by the northern storm. Hence, as on Earth, meteorological activity at mid-latitudes can have a profound effect on the regular atmospheric cycles in Saturn's tropics, demonstrating that waves can provide horizontal teleconnections between the phenomena shaping the middle atmospheres of giant planets.

  16. Brightness Temperatures of Saturn's Disk and Rings at 400 and 700 Micrometers.

    Science.gov (United States)

    Whitcomb, S E; Hildebrand, R H; Keene, J

    1980-11-14

    Saturn was observed in two broad submillimeter photometric bands with the rings nearly edge-on. The observed brightness temperatures fall below the predictions of atmospheric models constructed from data at shorter wavelenths, indicating the presence of an opacity source besides pressure-broadened hydrogen lines in the submillimeter region. In combination with earlier measurements at larger inclination angles, these results yield a 400-micrometer brightness temperature for the rings of approximately 75 K.

  17. Subjects great and small: Maxwell on Saturn's rings and kinetic theory.

    Science.gov (United States)

    Garber, Elizabeth

    2008-05-28

    Since 1890, James Clerk Maxwell's reputation has rested upon his theory of electromagnetism. However, during his lifetime he was recognized 'as the leading molecular scientist' of his generation. We will explore the foundation of his significance before 1890 using his work on the stability of Saturn's rings and the development of his kinetic theory of gases, and then briefly discuss the grounds for the change of his reputation.

  18. Precise Pointing for Radio Science Occultations and Radar Mapping During the Cassini Mission at Saturn

    Science.gov (United States)

    Burk, Thomas A.

    2015-01-01

    This paper discusses the implementation challenges and lessons learned from radar and radio science pointing observations during the Cassini mission at Saturn. Implementation of the precise desired pointing reveals key issues in the ground system, the flight system, and the pointing paradigm itself. To achieve accurate pointing on some observations, specific workarounds had to be implemented and folded into the sequence development process. Underlying Cassini's pointing system is a remarkable construct known as Inertial Vector Propagation.

  19. Saturn's upper atmosphere during the Voyager era: Reanalysis and modeling of the UVS occultations

    Science.gov (United States)

    Vervack, Ronald J.; Moses, Julianne I.

    2015-09-01

    The Voyager 1 and 2 Ultraviolet Spectrometer (UVS) solar and stellar occultation dataset represents one of the primary, pre-Cassini sources of information that we have on the neutral upper atmosphere of Saturn. Despite its importance, however, the full set of occultations has never received a consistent, nor complete, analysis, and the results derived from the initial analyses over thirty years ago left questions about the temperature and density profiles unanswered. We have reanalyzed all six of the UVS occultations (three solar and three stellar) to provide an up-to-date, pre-Cassini view of Saturn's upper atmosphere. From the Voyager UVS data, we have determined vertical profiles for H2, H, CH4, C2H2, C2H4, and C2H6, as well as temperature. Our analysis also provides explanations for the two different thermospheric temperatures derived in earlier analyses (400-450 K versus 800 K) and for the unusual shape of the total density profile noted by Hubbard et al. (1997). Aside from inverting the occultation data to retrieve densities and temperatures, we have investigated the atmospheric structure through a series of photochemical models to infer the strength of atmospheric mixing and other physical and chemical properties of Saturn's mesopause region during the Voyager flybys. We find that the data exhibit considerable variability in the vertical profiles for methane, suggesting variations in vertical winds or the eddy diffusion coefficient as a function of latitude and/or time in Saturn's upper atmosphere. The results of our reanalysis will provide a useful baseline for interpreting new data from Cassini, particularly in the context of change over the past three decades.

  20. The Faces of Saturn: Images and Texts from Augustus through Dürer to Galileo

    Science.gov (United States)

    Shank, M. H.

    2013-04-01

    This paper follows the thread(s) of Saturn in astrology and art from the Babylonians to Galileo, paying special attention to the planet's political importance from Augustus to the Medici and to its medical/psychological significance from Ficino through Dürer. In passing, I extend David Pingree's astrological interpretation of Dürer's Melencholia I and propose a very personal rationale for the engraving, namely as a memorial to his mother.

  1. Code Saturne: A Finite Volume Code for the computation of turbulent incompressible flows - Industrial Applications

    OpenAIRE

    Archambeau, Frédéric; Méchitoua, Namane; Sakiz, Marc

    2004-01-01

    International audience; This paper describes the finite volume method implemented in Code Saturne, Electricite de France general-purpose computational fluid dynamic code for laminar and turbulent flows in complex two and three- dimensional geometries. The code is used for industrial applications and research activities in several fields related to energy production (nuclear power thermal-hydraulics, gas and coal combustion, turbomachinery, heating, ventilation and air conditioning...). The se...

  2. Profiling of Code_Saturne with HPCToolkit and TAU, and autotuning Kernels with Orio

    OpenAIRE

    B. Lindia

    2014-01-01

    This study has profiled the application Code Saturne, which is part of the PRACE benchmark suite. The profiling has been carried out with the tools HPCtookit and Tuning and Analysis Utilities (TAU) with the target of finding compute kernels suitable for autotuning. Autotuning is regarded as a necessary step in achieving sustainable performance at an Exascale level as Exascale systems most likely will have a heterogeneous runtime environment. A heterogeneous runtime environment imp...

  3. Market Entry Strategies : Case: McDonald's entry on the Russian market

    OpenAIRE

    Karataev, Oleg

    2015-01-01

    The thesis considers the entry strategy and development of the company McDonald's into international markets. The theoretical aspects of the entry strategy of the company into the international markets. Analyzes the key features of the development of McDonald's in Russia. Investigated the prospects of the company in international markets. In theoretic part there was regarded some important aspects of international strategic management, such as: strategic alternatives, elements and levels o...

  4. The Atacama Cosmology Telescope: Beam Measurements and the Microwave Brightness Temperatures of Uranus and Saturn

    Science.gov (United States)

    Hasselfield, Matthew; Moodley, Kavilan; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Dunner, Rolando; Fowler, Joseph W.; Gallardo, Patricio; Gralla, Megan B.; hide

    2013-01-01

    We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures T(149/U) = 106.7 +/- 2.2 K and T(219/U) = 100.1 +/- 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of T(149/S) = 137.3 +/- 3.2 K and T(219/S) = 137.3 +/- 4.7 K.

  5. Comparing Jupiter and Saturn: dimensionless input rates from plasma sources within the magnetosphere

    Directory of Open Access Journals (Sweden)

    V. M. Vasyliūnas

    2008-06-01

    Full Text Available The quantitative significance for a planetary magnetosphere of plasma sources associated with a moon of the planet can be assessed only by expressing the plasma mass input rate in dimensionless form, as the ratio of the actual mass input to some reference value. Traditionally, the solar wind mass flux through an area equal to the cross-section of the magnetosphere has been used. Here I identify another reference value of mass input, independent of the solar wind and constructed from planetary parameters alone, which can be shown to represent a mass input sufficiently large to prevent corotation already at the source location. The source rate from Enceladus at Saturn has been reported to be an order of magnitude smaller (in absolute numbers than that from Io at Jupiter. Both reference values, however, are also smaller at Saturn than at Jupiter, by factors ~40 to 60; expressed in dimensionless form, the estimated mass input from Enceladus may be larger than that from Io by factors ~4 to 6. The magnetosphere of Saturn may thus, despite a lower mass input in kg s−1, intrinsically be more heavily mass-loaded than the magnetosphere of Jupiter.

  6. Low Frequency Extensions of the Saturn Kilometric Radiation as a Proxy for Magnetospheric Dynamics.

    Science.gov (United States)

    Reed, J.; Jackman, C. M.; Whiter, D. K.; Kurth, W. S.; Lamy, L.

    2016-12-01

    Saturn Kilometric Radiation (SKR) is a radio emission formed via the cyclotron maser instability on field aligned currents near the auroral regions of Saturn. The SKR has been found to respond to both internal and external driving, and to be linked to both solar wind compressions and magnetotail reconnection events. The radio emission is remotely sensed quasi-continuously and therefore offers the potential to be used as a proxy for magnetospheric activity when the spacecraft is not in an ideal viewing region for observing signatures of reconnection. In this work we use data taken by the Cassini magnetometer and radio and plasma wave sensor while Cassini was executing its deepest tail orbits in 2006. We characterise the behaviour of the SKR over this period and develop an automatic method for finding low frequency extensions (LFE), where the SKR emission extends down to lower frequencies below the main band. LFEs have been shown to occur in response to reconnection at Saturn (Jackman et al, 2009) and their appearance in Earth's analogous Auroral Kilometric Radiation (AKR) has been shown to coincide with substorm onset (e.g. Morioka et al, 2007). Using a new catalogue of LFEs we discuss their correlation with known tail reconnection events and solar wind shocks (as inferred from the use of propagated solar wind models). We also look at their properties such as length and recurrence rate, as well as their relationship to the planetary periodicities.

  7. Dynamics Of Saturn'S Mid-scale Storms In The Cassini Era.

    Science.gov (United States)

    Del Rio Gaztelurrutia, Teresa; Hueso, R.; Sánchez-Lavega, A.

    2010-10-01

    Convective storms, similar to those in Earth, but of much larger scale, develop often in Saturn's atmosphere. During the Voyagers’ flybys of Saturn in 1981 mid-scale storms, with an horizontal extension of the order of 1000-3000 km were observed to occur mainly in a narrow tropical-latitude band in the Northern hemisphere at latitudes 38-40 deg North. Contrasting with the Voyagers’ era, since the starting of the Cassini mission in 2004, a similar mid-scale convective activity has concentrated in the so-called "storm alley", a narrow band at a symmetric Southern latitude of 38 deg.. In this work, we characterize this storm activity using available visual information provided by Cassini ISS cameras and the continuous survey from the Earth by the International Outer Planets Watch (IOPW) and its online database PVOL (Hueso et al., Planetary and Space Science, 2010). We study the frequency of appearance of storms with sizes above 2000 km, their characteristic size and life-time, as well as their interaction with surrounding dynamical features. In particular we examine the possibility that storms might provide a mechanism of injection of energy into Saturn's jets, the influence of storms in the generation of atmospheric vortices, and the analogies and differences of Voyagers’ and present day jet structure at the relevant latitudes. Acknowledgments: This work has been funded by the Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464

  8. MEANDERING SHALLOW ATMOSPHERIC JET AS A MODEL OF SATURN'S NORTH-POLAR HEXAGON

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Juberías, R.; Cosentino, R. G. [Physics Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States); Sayanagi, K. M. [Atmospheric and Planetary Sciences Department, Hampton University, Hampton VA 23668 (United States); Simon, A. A. [Solar System Exploration Division, NASA/GSFC, Greenbelt MD 20771 (United States); Fletcher, L. N., E-mail: rmjuberias@gmail.com [Atmospheric, Oceanic and Planetary Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)

    2015-06-10

    The Voyager flybys of Saturn in 1980–1981 revealed a circumpolar Hexagon at ∼78° north planetographic latitude that has persisted for over 30 Earth years, more than one Saturn year, and has been observed by ground-based telescopes, Hubble Space Telescope and multiple instruments on board the Cassini orbiter. Its average phase speed is very slow with respect to the System III rotation rate, defined by the primary periodicity in the Saturn Kilometric Radiation during the Voyager era. Cloud tracking wind measurements reveal the presence of a prograde jet-stream whose path traces the Hexagon’s shape. Previous numerical models have produced large-amplitude, n = 6, wavy structures with westward intrinsic phase propagation (relative to the jet). However, the observed net phase speed has proven to be more difficult to achieve. Here we present numerical simulations showing that instabilities in shallow jets can equilibrate as meanders closely resembling the observed morphology and phase speed of Saturn’s northern Hexagon. We also find that the winds at the bottom of the model are as important as the winds at the cloud level in matching the observed Hexagon’s characteristics.

  9. Radial profiles of the Phoebe ring: A vast debris disk around Saturn

    Science.gov (United States)

    Tamayo, Daniel; Markham, Stephen R.; Hedman, Matthew M.; Burns, Joseph A.; Hamilton, Douglas P.

    2016-09-01

    We present observations at optical wavelengths with the Cassini Spacecraft's Imaging Science System of the Phoebe ring, a vast debris disk around Saturn that seems to be collisionally generated by its irregular satellites. The analysis reveals a radial profile from 80-260 Saturn radii (RS) that changes behavior interior to ≈110RS. We attribute this to either the moon Iapetus...sweeping up small particles, or to orbital instabilities that cause the ring to flare up vertically. Our study yields an integrated I/F at 0.635 μm along Saturn's shadow in the Phoebe ring's midplane from 80-250 RS of 2.7-0.3+0.9 ×10-9 . We develop an analytical model for the size-dependent secular dynamics of retrograde Phoebe ring grains, and compare this model to the observations. This analysis implies that 1) the "Phoebe" ring is partially sourced by debris from irregular satellites beyond Phoebe's orbit and 2) the scattered light signal is dominated by small grains (≲20 μm in size). If we assume that the Phoebe ring is generated through steady-state micrometeoroid bombardment, this implies a power-law size distribution with index >4, which is unusually steep among Solar System rings. This suggests either a steep size distribution of ejecta when material is initially released, or a subsequent process that preferentially breaks up large grains.

  10. Meandering Shallow Atmospheric Jet as a Model of Saturn's North-polar Hexagon

    Science.gov (United States)

    Morales-Juberías, R.; Sayanagi, K. M.; Simon, A. A.; Fletcher, L. N.; Cosentino, R. G.

    2015-06-01

    The Voyager flybys of Saturn in 1980-1981 revealed a circumpolar Hexagon at ˜78° north planetographic latitude that has persisted for over 30 Earth years, more than one Saturn year, and has been observed by ground-based telescopes, Hubble Space Telescope and multiple instruments on board the Cassini orbiter. Its average phase speed is very slow with respect to the System III rotation rate, defined by the primary periodicity in the Saturn Kilometric Radiation during the Voyager era. Cloud tracking wind measurements reveal the presence of a prograde jet-stream whose path traces the Hexagon’s shape. Previous numerical models have produced large-amplitude, n = 6, wavy structures with westward intrinsic phase propagation (relative to the jet). However, the observed net phase speed has proven to be more difficult to achieve. Here we present numerical simulations showing that instabilities in shallow jets can equilibrate as meanders closely resembling the observed morphology and phase speed of Saturn’s northern Hexagon. We also find that the winds at the bottom of the model are as important as the winds at the cloud level in matching the observed Hexagon’s characteristics.

  11. Comparing Jupiter and Saturn: dimensionless input rates from plasma sources within the magnetosphere

    Directory of Open Access Journals (Sweden)

    V. M. Vasyliūnas

    2008-06-01

    Full Text Available The quantitative significance for a planetary magnetosphere of plasma sources associated with a moon of the planet can be assessed only by expressing the plasma mass input rate in dimensionless form, as the ratio of the actual mass input to some reference value. Traditionally, the solar wind mass flux through an area equal to the cross-section of the magnetosphere has been used. Here I identify another reference value of mass input, independent of the solar wind and constructed from planetary parameters alone, which can be shown to represent a mass input sufficiently large to prevent corotation already at the source location. The source rate from Enceladus at Saturn has been reported to be an order of magnitude smaller (in absolute numbers than that from Io at Jupiter. Both reference values, however, are also smaller at Saturn than at Jupiter, by factors ~40 to 60; expressed in dimensionless form, the estimated mass input from Enceladus may be larger than that from Io by factors ~4 to 6. The magnetosphere of Saturn may thus, despite a lower mass input in kg s−1, intrinsically be more heavily mass-loaded than the magnetosphere of Jupiter.

  12. Ultralow Frequency Waves In Saturn's Magnetosphere: More Than Ion Cyclotron Waves

    Science.gov (United States)

    Crary, Frank; Dols, Vincent; Usanova, Maria; Meeks, Zachary; Simon, Sven

    2017-04-01

    Electromagnetic waves near the oxygen/water group cyclotron frequency are an ubiquitous feature of Saturn's inner magnetosphere. These left-circularly polarized, transverse waves are generated by the anisotropic velocity distribution of recently produced ions, and reflect the ion production rate. The properties and distribution of these emissions have been previous studies and related to the distribution of neutrals in the system (Leisner et al., 2006; Crary et al., 2013; Meeks et al., 2016.) In addition to these waves, other, related mode have been observed by the Cassini spacecraft. The waves near the W+ (water group) cyclotron frequency sometimes have a compressional component and/or accompanying emission the first (2f) harmonic (implying the waves are oblique rather than parallel propagating. Neither of these properties is predicted by the classic theory of wave growth from a ring-beam distribution. In addition, ion cyclotron waves are also observed near the gyrofrequency of a 32 AMU ion, suggesting production of O2+. While observed, O2+ is a very low abundance species outside of 4 Saturn radii, and in the regions where these waves are present. Finally, strong but linearly polarized waves are sometimes observed near the orbit of Enceladus. The association between these waves and W+ ion cyclotron waves is unclear. We will present the measurements of these ULF waves, their frequency of occurrence with respect to position and time, and discuss their implications for plasma production in Saturn's magnetosphere.

  13. Survey of thermal plasma ions in Saturn's magnetosphere utilizing a forward model

    Science.gov (United States)

    Wilson, R. J.; Bagenal, F.; Persoon, A. M.

    2017-07-01

    The Cassini Plasma Spectrometer instrument gathered thermal ion data at Saturn from 2004 to 2012, predominantly observing water group ions and protons. Plasma parameters, with uncertainties, for those two ion species are derived using a forward model of anisotropic convected Maxwellians moving at a shared velocity. The resulting data set is filtered by various selection criteria to produce a survey of plasma parameters derived within 10° of the equator at radial distances of 5.5 to 30 RS (1 RS = Saturn's radius). The previous 2008 work used a simpler method and had just 150 records over 5 orbits; this comprehensive survey has 9736 records over all 9 years. We present the results of this survey and compare them with a previous survey derived from numerical moments, highlighting the differences between the reported densities and temperatures from the two methods. Radial profiles of the plasma parameters in the inner and middle magnetospheres out to ≈22RS are stable year by year, but variable at distances larger than 23 RS near the magnetopause. New results include proton densities increasing in the near magnetopause region, suggestive of plasma mixing; evidence for the global electric field in Saturn's inner magnetosphere extends out to ≈15RS; no evidence for supercorotating plasma nor the middle magnetosphere "plasma cam" feature is present; the thermal plasma β is found to exceed unity at equatorial distances greater than 15 RS.

  14. Dawn-dusk asymmetries in rotating magnetospheres: Lessons from modeling Saturn

    Science.gov (United States)

    Jia, Xianzhe; Kivelson, Margaret G.

    2016-02-01

    Spacecraft measurements reveal perplexing dawn-dusk asymmetries of field and plasma properties in the magnetospheres of Saturn and Jupiter. Here we describe a previously unrecognized source of dawn-dusk asymmetry in a rapidly rotating magnetosphere. We analyze two magnetohydrodynamic simulations, focusing on how flows along and across the field vary with local time in Saturn's dayside magnetosphere. As plasma rotates from dawn to noon on a dipolarizing flux tube, it flows away from the equator along the flux tube at roughly half of the sound speed (Cs), the maximum speed at which a bulk plasma can flow along a flux tube into a lower pressure region. As plasma rotates from noon to dusk on a stretching flux tube, the field-aligned component of its centripetal acceleration decreases and it flows back toward the equator at speeds typically smaller than 1/2 Cs. Correspondingly, the plasma sheet remains far thicker and the field less stretched in the afternoon than in the morning. Different radial force balance in the morning and afternoon sectors produce asymmetry in the plasma sheet thickness and a net dusk-to-dawn flow inside of L = 15 or equivalently, a large-scale electric field (E) oriented from postnoon to premidnight, as reported from observations. Morning-afternoon asymmetry analogous to that found at Saturn has been observed at Jupiter, and a noon-midnight component of E cannot be ruled out.

  15. Hard Probes at ATLAS

    CERN Document Server

    Citron, Z; The ATLAS collaboration

    2014-01-01

    The ATLAS collaboration has measured several hard probe observables in Pb+Pb and p+Pb collisions at the LHC. These measurements include jets which show modification in the hot dense medium of heavy ion collisions as well as color neutral electro-weak bosons. Together, they elucidate the nature of heavy ion collisions.

  16. The solar probe antenna

    Science.gov (United States)

    Imbriale, W. A.; Randolph, J. E.; Embuido, E.

    2004-01-01

    This paper details the design of the antenna intended for use on the Solar Probe Mission. The antenna consists of a carbon-carbon reflector jointly used as the antenna and thermal shield and helical feed using tungsten wire and ceramic matrix composite (CMC) materials for the back plate, coaxial cable waveguide. A complete prototype feed assembly was fabricated and tested.

  17. Probing the Solar Interior

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 3. Probing the Solar Interior Hearing the Heartbeats of the Sun. Ashok Ambastha. General Article Volume 3 Issue 3 March 1998 pp 18-31. Fulltext. Click here to view fulltext PDF. Permanent link:

  18. Mobile Probing Kit

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Sørensen, Lene Tolstrup; Sørensen, J.K.

    2007-01-01

    Mobile Probing Kit is a low tech and low cost methodology for obtaining inspiration and insights into user needs, requirements and ideas in the early phases of a system's development process. The methodology is developed to identify user needs, requirements and ideas among knowledge workers...

  19. Terahertz scanning probe microscope

    NARCIS (Netherlands)

    Klapwijk, T.M.

    2014-01-01

    The invention provides aterahertz scanning probe microscope setup comprising (i) a terahertz radiation source configured to generate terahertz radiation; (ii) a terahertz lens configured to receive at least part of the terahertz radiation from the terahertz radiation source; (iii) a cantilever unit

  20. One-Probe Search

    DEFF Research Database (Denmark)

    Östlin, Anna; Pagh, Rasmus

    2002-01-01

    We consider dictionaries that perform lookups by probing a single word of memory, knowing only the size of the data structure. We describe a randomized dictionary where a lookup returns the correct answer with probability 1 - e, and otherwise returns don't know. The lookup procedure uses an expan...