WorldWideScience

Sample records for ranging messenger spacecraft

  1. MESSENGER Spacecraft and Payload Performance

    Science.gov (United States)

    Gold, R. E.; Solomon, S. C.; McNutt, J. R., Jr.; Leary, J. C.; MESSENGER Team

    The Mercury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, launched in May of this year, will be the first spacecraft to orbit the planet Mercury. The >14 kWm-2 solar thermal input and the large velocity change required to reach Mercury orbit make this a very challenging mission from thermal and mass perspectives. MESSENGER overcomes these challenges with innovative applications of existing technologies and materials. The spacecraft uses ordinary space electronics, has minimal moving parts, and has extensive redundancy and cross strapping to enhance its robustness. The major innovations are a ceramic-cloth thermal shade, an integrated lightweight structure, a high-performance propulsion system, and a solar array incorporating optical solar reflectors to prevent overheating. Seven miniaturized instruments, along with the spacecraft telecommunications system, satisfy all scientific objectives of the mission. The payload includes a dual imaging system with wide-angle and narrow-angle cameras; an integrated ultraviolet, visible, and infrared spectrometer that is sensitive enough to detect atmospheric emissions and robust enough to map mineralogical absorption features on the sun-lit surface; gamma-ray, X-ray, and neutron spectrometers for remote geochemical mapping; a vector magnetometer; a laser altimeter to determine the topography of surface features and determine whether Mercury has a fluid core; and an energetic particle and plasma spectrometer to characterize ionized species in the magnetosphere. The payload was fully calibrated before launch, and an additional series of calibration measurements are planned during the 5-year cruise to Mercury. The first of the three Venus flybys and two Mercury flybys during the cruise phase of the mission will occur in November 2004

  2. Thermal Design and Performance of the Gamma-Ray Spectrometer for the MESSENGER Spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Burks, M; Cork, C P; Eckels, D; Hull, E; Madden, N W; Miller, W; Goldsten, J; Rhodes, E; Williams, B

    2004-10-13

    A gamma-ray spectrometer (GRS) has been built and delivered to the Mercury MESSENGER spacecraft which launched on August 3, 2004, from Cape Canaveral, Florida. The GRS, a part of seven scientific instruments on board MESSENGER, is based on a coaxial high-purity germanium detector. Gamma-ray detectors based on germanium have the advantage of providing excellent energy resolution, which is critical to achieving the science goals of the mission. However, germanium has the disadvantage that it must operate at cryogenic temperatures (typically {approx}80 K). This requirement is easy to satisfy in the laboratory but difficult near Mercury, which has an extremely hot thermal radiation environment. To cool the detector, a Stirling cycle mechanical cooler is employed. In addition, radiation and conduction techniques a are used to reduce the GRS heat load. Before delivering the flight sensor, a complete thermal prototype was built and tested. The results of these test, including thermal design, radiative and conductive heat loads, and cooler performance are described.

  3. High Dynamic Range Digital Imaging of Spacecraft

    Science.gov (United States)

    Karr, Brian A.; Chalmers, Alan; Debattista, Kurt

    2014-01-01

    The ability to capture engineering imagery with a wide degree of dynamic range during rocket launches is critical for post launch processing and analysis [USC03, NNC86]. Rocket launches often present an extreme range of lightness, particularly during night launches. Night launches present a two-fold problem: capturing detail of the vehicle and scene that is masked by darkness, while also capturing detail in the engine plume.

  4. MESSENGER, MErcury: Surface, Space ENvironment, GEochemistry, and Ranging; A Mission to Orbit and Explore the Planet Mercury

    Science.gov (United States)

    1999-01-01

    MESSENGER is a scientific mission to Mercury. Understanding this extraordinary planet and the forces that have shaped it is fundamental to understanding the processes that have governed the formation, evolution, and dynamics of the terrestrial planets. MESSENGER is a MErcury Surface, Space ENvironment, GEochemistry and Ranging mission to orbit Mercury for one Earth year after completing two flybys of that planet following two flybys of Venus. The necessary flybys return significant new data early in the mission, while the orbital phase, guided by the flyby data, enables a focused scientific investigation of this least-studied terrestrial planet. Answers to key questions about Mercury's high density, crustal composition and structure, volcanic history, core structure, magnetic field generation, polar deposits, exosphere, overall volatile inventory, and magnetosphere are provided by an optimized set of miniaturized space instruments. Our goal is to gain new insight into the formation and evolution of the solar system, including Earth. By traveling to the inner edge of the solar system and exploring a poorly known world, MESSENGER fulfills this quest.

  5. Geodesy at Mercury with MESSENGER

    Science.gov (United States)

    Smith, David E.; Zuber, Maria t.; Peale, Stanley J.; Phillips, Roger J.; Solomon, Sean C.

    2006-01-01

    In 2011 the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft will enter Mercury orbit and begin the mapping phase of the mission. As part of its science objectives the MESSENGER mission will determine the shape and gravity field of Mercury. These observations will enable the topography and the crustal thickness to be derived for the planet and will determine the small libration of the planet about its axis, the latter critical to constraining the state of the core. These measurements require very precise positioning of the MESSENGER spacecraft in its eccentric orbit, which has a periapsis altitude as low as 200 km, an apoapsis altitude near 15,000 km, and a closest approach to the surface varying from latitude 60 to about 70 N. The X-band tracking of MESSENGER and the laser altimetry are the primary data that will be used to measure the planetary shape and gravity field. The laser altimeter, which has an expected range of 1000 to 1200 km, is expected to provide significant data only over the northern hemisphere because of MESSENGER's eccentric orbit. For the southern hemisphere, radio occultation measurements obtained as the spacecraft passes behind the planet as seen from Earth and images obtained with the imaging system will be used to provide the long-wavelength shape of the planet. Gravity, derived from the tracking data, will also have greater resolution in the northern hemisphere, but full global models for both topography and gravity will be obtained at low harmonic order and degree. The limiting factor for both gravity and topography is expected to be knowledge of the spacecraft location. Present estimations are that in a combined tracking, altimetry, and occultation solution the spacecraft position uncertainty is likely to be of order 10 m. This accuracy should be adequate for establishing an initial geodetic coordinate system for Mercury that will enable positioning of imaged features on the surface, determination of

  6. Two-Step Laser Ranging for Precise Tracking of a Spacecraft

    Science.gov (United States)

    Chui, Talso; Penanen, Konstantin

    2005-01-01

    A document proposes a two-step laser ranging technique for precise tracking of a coasting interplanetary spacecraft to determine the degree to which leakage of fuel, solar wind, and/or solar-radiation pressure causes it to deviate from a purely gravitational trajectory. Such a determination could contribute to the precision of a test of a theory of gravitation. In the technique, a proof mass would be released from the spacecraft. By use of laser ranging equipment on the spacecraft and retroreflectors attached to the proof mass, the relative position of the spacecraft and proof mass would be determined. Meanwhile, the position of the spacecraft relative to the Earth would be determined by ranging by use of a laser transponder. The vector sum of the two sets of ranging measurements would be the position of the proof mass relative to the Earth. Unlike the acceleration of the spacecraft, the acceleration of the proof mass should not include a residual component attributable to leakage of fuel. In addition, the effects of solar radiation and solar wind on the proof mass could be minimized by releasing the proof mass into the shadow of the spacecraft.

  7. Mercury after three MESSENGER flybys

    Science.gov (United States)

    Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Prockter, Louise M.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Murchie, Scott L.; Nittler, Larry R.; Phillips, Roger J.; Zuber, Maria T.

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) space-craft, developed under NASA's Discovery Program, is the first space probe to visit the planet Mercury in more than 30 years. MESSENGER flew by the innermost planet twice in 2008 and once last fall. The flybys confirmed that Mercury's internal magnetic field is dominantly dipolar, with a vector moment closely aligned with the spin axis. MESSENGER detected mag-nesium in Mercury's exosphere, demonstrated that Mercury's anti-sunward neutral tail contains multiple species, and revealed that the distributions of sodium, calcium, and magnesium in the exosphere and tail vary differently with latitude, time of day, and Mercury's position in or-bit, signatures of multiple source processes. MESSENGER's laser altimeter showed that the equatorial topographic relief of Mercury exceeds 5 km, revealed an equatorial ellipticity aligned with the ellipticity in Mercury's gravitational potential, and documented the form of numer-ous impact craters and fault scarps. MESSENGER images provided evidence for widespread volcanism, and candidate sites for volcanic centers were identified. In addition, newly imaged lobate scarps and other tectonic landforms support the hypothesis that Mercury contracted globally in response to interior cooling. The ˜1500-km-diameter Caloris basin, viewed in its entirety for the first time by MESSENGER, was the focus for concentrations of volcanic cen-ters, some with evidence of pyroclastic deposits, and widespread contractional and extensional deformation; smooth plains interior and exterior to the basin are demonstrably younger than the basin-forming event. The ˜700-km-diameter Rembrandt basin, less volcanically infilled than Caloris, was likewise a focus for concentrated magmatic and deformational activity. A ˜290-km-diameter basin contains interior plains that are among the youngest volcanic material on the planet. The nearly global observations of Mercury surface units

  8. Mountain ranges in western Pakistan as seen from the Apollo 7 spacecraft

    Science.gov (United States)

    1968-01-01

    Toba, Kakar, Fort Sandeman, Sulaiman Range area in west Pakistan as seen from the Apollo 7 spacecraft during its 84th revolution of the earth. Note geological features such as folded mountain structures, anticlines and synclines. Photographed from an altitude of 108 nautical miles, at ground elapsed time of 132 hours and 30 minutes.

  9. Testing the strong equivalence principle with spacecraft ranging towards the nearby Lagrangian points

    Science.gov (United States)

    Congedo, Giuseppe; De Marchi, Fabrizio

    2016-05-01

    General relativity is supported by great experimental evidence. Yet there is a lot of interest in precisely setting its limits with on going and future experiments. A question to answer is about the validity of the strong equivalence principle. Ground experiments and lunar laser ranging have provided the best upper limit on the Nordtvedt parameter σ [η ]=4.4 ×10-4 . With the future planetary mission BepiColombo, this parameter will be further improved by at least an order of magnitude. In this paper we envisage yet another possible testing environment with spacecraft ranging towards the nearby Sun-Earth collinear Lagrangian points. Neglecting errors in planetary masses and ephemerides, we forecast σ [η ]=6.4 (2.0 )×10-4 (5 yr integration time) via ranging towards L1 in a realistic (optimistic) scenario depending on current (future) range capabilities and knowledge of the Earth's ephemerides. A combined measurement, L1+L2, gives instead 4.8 (1.7 )×10-4. In the optimistic scenario a single measurement of one year would be enough to reach ≈3 ×10-4. All figures are comparable with lunar laser ranging, but worse than BepiColombo. Performances could be much improved if data were integrated over time and over the number of satellites flying around either of the two Lagrangian points. We point out that some systematics (gravitational perturbations of other planets or figure effects) are much more in control compared to other experiments. We do not advocate a specific mission to constrain the strong equivalence principle, but we do suggest analyzing ranging data of present and future spacecrafts flying around L1/L2 (one key mission is, for instance, LISA Pathfinder). This spacecraft ranging would be a new and complementary probe to constrain the strong equivalence principle in space.

  10. The Messenger Mission to Mercury

    CERN Document Server

    Domingue, D. L

    2007-01-01

    NASA’s MESSENGER mission, launched on 3 August, 2004 is the seventh mission in the Discovery series. MESSENGER encounters the planet Mercury four times, culminating with an insertion into orbit on 18 March 2011. It carries a comprehensive package of geophysical, geological, geochemical, and space environment experiments to complete the complex investigations of this solar-system end member, which begun with Mariner 10. The articles in this book, written by the experts in each area of the MESSENGER mission, describe the mission, spacecraft, scientific objectives, and payload. The book is of interest to all potential users of the data returned by the MESSENGER mission, to those studying the nature of the planet Mercury, and by all those interested in the design and implementation of planetary exploration missions.

  11. Development of a Radio Frequency Space Environment Path Emulator for Evaluating Spacecraft Ranging Hardware

    Science.gov (United States)

    Mitchell, Jason W.; Baldwin, Philip J.; Kurichh, Rishi; Naasz, Bo J.; Luquette, Richard J.

    2007-01-01

    The Formation Flying Testbed (FFTB) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility is evolving as a modular, hybrid, dynamic simulation facility for end-to-end guidance, navigation and. control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, have expanded to include S-band Radio Frequency (RF) modems for inter-spacecraft communication and ranging. To enable realistic simulations that require RF ranging sensors for relative navigation, a mechanism is needed to buffer the RF signals exchanged between spacecraft that accurately emulates the dynamic environment through which the RF signals travel, including the effects of medium, moving platforms, and radiated power. The Path Emulator for RF Signals (PERFS), currently under development at NASA GSFC, provides this capability. The function and performance of a prototype device are presented.

  12. Characterization of a Prototype Radio Frequency Space Environment Path Emulator for Evaluating Spacecraft Ranging Hardware

    Science.gov (United States)

    Mitchell, Jason W.; Baldwin, Philip J.; Kurichh, Rishi; Naasz, Bo J.; Luquette, Richard J.

    2007-01-01

    The Formation Flying Testbed (FFTB) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility is evolving as a modular, hybrid, dynamic simulation facility for end-to-end guidance, navigation and control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, have expanded to include S-band Radio Frequency (RF) modems for interspacecraft communication and ranging. To enable realistic simulations that require RF ranging sensors for relative navigation, a mechanism is needed to buffer the RF signals exchanged between spacecraft that accurately emulates the dynamic environment through which the RF signals travel, including the effects of the medium, moving platforms, and radiated power. The Path Emulator for Radio Frequency Signals (PERFS), currently under development at NASA GSFC, provides this capability. The function and performance of a prototype device are presented.

  13. Translational Influence on Messenger Stability

    DEFF Research Database (Denmark)

    Eriksen, Mette

    RNA messenger stability is in uenced by how well it is protected from ribonuclase degradation. The level and distribution of translating ribosomes on the messenger has an effect on messenger stability, which is tuned partly by the nature of the ribosome binding site and partly by the codon...... composition of the coding sequence of a gene. This thesis focussed on illuminating the impact of ribosome binding sites on the functional messenger half-life using a range of ribosome binding sites with altered binding strength. Furthermore, the additive in uence of the transcription terminator, Rho......, on messenger stability was examined. Depending on the translation initiation frequency, the chance of an initial ribosome trailing the RNA polymerase get better for better initiation sites, thus protecting transcription from termination by Rho. A polarity assay in which the activity of the downstream lac...

  14. MESSENGER: Exploring the Innermost Planet

    Science.gov (United States)

    Solomon, S. C.

    2011-12-01

    One of Earth's closest planetary neighbors, Mercury remained comparatively unexplored for the more than three decades that followed the three flybys of the innermost planet by the Mariner 10 spacecraft in 1974-75. Mariner 10 imaged 45% of Mercury's surface at about 1 km/pixel average resolution, confirmed Mercury's anomalously high bulk density and implied large fractional core size, discovered Mercury's internal magnetic field, documented that H and He are present in the planet's tenuous exosphere, and made the first exploration of Mercury's magnetosphere and solar wind environment. Ground-based astronomers later reported Na, K, and Ca in Mercury's exosphere; the presence of deposits in the floors of polar craters having radar characteristics best matched by water ice; and strong evidence from the planet's forced libration amplitude that Mercury has a fluid outer core. Spacecraft exploration of Mercury resumed with the selection for flight, under NASA's Discovery Program, of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. Launched in 2004, MESSENGER flew by the innermost planet three times in 2008-2009 en route to becoming the first spacecraft to orbit Mercury in March of this year. MESSENGER's first chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction differs from those of the other inner planets, with a low-Fe surface composition intermediate between basalts and ultramafic rocks and best matched among terrestrial rocks by komatiites. Moreover, surface materials are richer in the volatile constituents S and K than predicted by most planetary formation models. Global image mosaics and targeted high-resolution images (to resolutions of 10 m/pixel) reveal that Mercury experienced globally extensive volcanism, including large expanses of plains emplaced as flood lavas and widespread examples of pyroclastic deposits likely emplaced during explosive eruptions of volatile

  15. Unsupervised Classification of MESSENGER MASC Data

    Science.gov (United States)

    de Sanctis, M. Cristina; Capaccioni, Fabrizio; Filacchione, Gianrico; Ammannito, Eleonora

    2010-05-01

    The MESSENGER spacecraft flew by Mercury as part of its journey to Mercury orbit insertion. The Mercury At-mospheric and Surface Composition Spectrometer (MASCS) observed Mercury during the first two flybys, includ-ing high-spatial-and spectral-resolution visible to near-infrared (IR) spectra of the Mercury surface. The Visible and InfraRed Spectrograph (VIRS) component of MASCS consists of two linear photodiode arrays covering a spectral range 320-1450 nm. We applied classification method to MASCS data in order to extract information on the mineralogy of Mercury. The classification of the Messenger data will permit to obtain maps of Mercury surface, giving us indication of the different mineralogy and maturity present on the Hermean surface. The data were pre-processed applying photometric correction and the VIS and NIR data were collected in a single spectrum. The data set show very similar featureless spectra. The main differences are in the reflectance levels and in the spectral slopes. To emphasize the spectral differences we have normalized the spectra to an average reflectance spectrum for each flyby. This allows to point out variation of different regions with respect to the aver-age spectral behaviour. Two different approaches have been used to analyze MASCS data of the two Messenger flybys: ISODATA unsupervised classification and a classification based on three different spectral slopes (in the wavelengths' ranges 0.3-0.55, 0.55-0.8 and 0.95-1.49 µm). The identified classes shows differences linked with slopes and reflectance's level: the proposed methods allows to correlate the most important classes with different morphological features on Mercury's surface which differ for weathering, maturity and composition. Our analysis is done in order to test and verify these classification methods that shall be necessary to analyze similar data harvested by SIMBIO-SYS/VIHI (Visible and Infrared Hyper-spectral Imager) aboard the future ESA's BepiColombo mission

  16. Mercury's rotational state from combined MESSENGER laser altimeter and image data

    Science.gov (United States)

    Stark, Alexander; Oberst, Jürgen; Preusker, Frank; Margot, Jean-Luc; Phillips, Roger J.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.

    2016-04-01

    With orbital data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, we measured the rotational state of Mercury. We developed a novel approach that combined digital terrain models from stereo images (stereo DTMs) and laser altimeter data, and we applied it to 3 years of MESSENGER observations. We find a large libration amplitude, which in combination with the measured obliquity confirms that Mercury possesses a liquid outer core. Our results confirm previous Earth-based observations of Mercury's rotational state. However, we measured a rotation rate that deviates significantly from the mean resonant rotation rate. The larger rotation rate can be interpreted as the signature of a long-period libration cycle. From these findings we derived new constraints on the interior structure of Mercury. The measured rotational parameters define Mercury's body-fixed frame and are critical for the coordinate system of the planet as well as for planning the future BepiColombo spacecraft mission.

  17. Mercury's Sodium Exosphere: Observations during the MESSENGER Orbital Phase

    Science.gov (United States)

    Killen, Rosemary M.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; Burger, Matthew H.; Merkel, Aimee W.; Sarantos, Menelaos; Sprague, Ann L.; McClintock, William E.; Benna, Mehdi; Solomon, Sean C.

    2012-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered into orbit about Mercury on March 18,2011. We now have approximately five Mercury years of data from orbit. Prior to the MESSENGER mission, Mercury's surface-bounded exosphere was known to contain H, He, Na. K, and Ca. The Ultraviolet and Visible Spectrometer (UVVS) began routine orbital observations of both the dayside and nightside exosphere on March 29. 2011, measuring altitude profiles for all previously detected neutral species except for He and K. We focus here on what we have learned about the sodium exosphere: its spatial, seasonal, and sporadic variation. Observations to date permit delineation of the relative roles of photon-stimulated desorption (PSD) and impact vaporization (IV) from seasonal and spatial effects, as well as of the roles of ions both as sputtering agents and in their possible role to enhance the efficiency of PSD. Correlations of Mercury's neutral sodium exosphere with measurements from MESSENGER's Magnetometer (MAG) and Energetic Particle and Plasma Spectrometer (EPPS) provide insight into the roles of ions and electrons. Models incorporating MAG observations provide a basis for identifying the location and area of the surface exposed to solar wind plasma, and EPPS observations reveal episodic populations of energetic electrons in the magnetosphere and the presence of planetary He(+), 0(+), and Na(+),

  18. A Test of General Relativity with MESSENGER Mission Data

    Science.gov (United States)

    Genova, A.; Mazarico, E.; Goossens, S. J.; Lemoine, F. G.; Neumann, G. A.; Nicholas, J. B.; Rowlands, D. D.; Smith, D. E.; Zuber, M. T.; Solomon, S. C.

    2016-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft initiated collection of scientific data from the innermost planet during its first flyby of Mercury in January 2008. After two additional Mercury flybys, MESSENGER was inserted into orbit around Mercury on 18 March 2011 and operated for more than four Earth years through 30 April 2015. Data acquired during the flyby and orbital phases have provided crucial information on the formation and evolution of Mercury. The Mercury Laser Altimeter (MLA) and the radio science system, for example, obtained geodetic observations of the topography, gravity field, orientation, and tides of Mercury, which helped constrain its surface and deep interior structure. X-band radio tracking data collected by the NASA Deep Space Network (DSN) allowed the determination of Mercury's gravity field to spherical harmonic degree and order 100, as well as refinement of the planet's obliquity and estimation of the tidal Love number k2. These geophysical parameters are derived from the range-rate observables that measure precisely the motion of the spacecraft in orbit around the planet. However, the DSN stations acquired two other kinds of radio tracking data, range and delta-differential one-way ranging, which also provided precise measurements of Mercury's ephemeris. The proximity of Mercury's orbit to the Sun leads to a significant perihelion precession, which was used by Einstein as confirmation of general relativity (GR) because of its inconsistency with the effects predicted from classical Newtonian theory. MESSENGER data allow the estimation of the GR parameterized post-Newtonian (PPN) coefficients γ and β. Furthermore, determination of Mercury's orbit also allows estimation of the gravitational parameter (GM) and the flattening (J2) of the Sun. We modified our orbit determination software, NASA GSFC's GEODYN II, to enable simultaneous orbit integration of both MESSENGER and the planet Mercury. The

  19. Transmembrane Signalling: Membrane messengers

    Science.gov (United States)

    Cockroft, Scott L.

    2017-05-01

    Life has evolved elaborate means of communicating essential chemical information across cell membranes. Inspired by biology, two new artificial mechanisms have now been developed that use synthetic messenger molecules to relay chemical signals into or across lipid membranes.

  20. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    Science.gov (United States)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.; Sarantos, Menelaos

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variations, but there are no obvious year-to-year variations in most of the observations. We do not see the episodic variability reported by some ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere, at about 1200 K, is much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  1. A comprehensive study of Mercury and MESSENGER orbit determination

    Science.gov (United States)

    Genova, Antonio; Mazarico, Erwan; Goossens, Sander; Lemoine, Frank G.; Neumann, Gregory A.; Nicholas, Joseph B.; Rowlands, David D.; Smith, David E.; Zuber, Maria; Solomon, Sean C.

    2016-10-01

    The MErcury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited the planet Mercury for more than 4 years. The probe started its science mission in orbit around Mercury on 18 March 2011. The Mercury Laser Altimeter (MLA) and radio science system were the instruments dedicated to geodetic observations of the topography, gravity field, orientation, and tides of Mercury. X-band radio-tracking range-rate data collected by the NASA Deep Space Network (DSN) allowed the determination of Mercury's gravity field to spherical harmonic degree and order 100, the planet's obliquity, and the Love number k2.The extensive range data acquired in orbit around Mercury during the science mission (from April 2011 to April 2015), and during the three flybys of the planet in 2008 and 2009, provide a powerful dataset for the investigation of Mercury's ephemeris. The proximity of Mercury's orbit to the Sun leads to a significant perihelion precession attributable to the gravitational flattening of the Sun (J2) and the Parameterized Post-Newtonian (PPN) coefficients γ and β, which describe the space curvature produced by a unit rest mass and the nonlinearity in superposition of gravity, respectively. Therefore, the estimation of Mercury's ephemeris can provide crucial information on the interior structure of the Sun and Einstein's general theory of relativity. However, the high correlation among J2, γ, and β complicates the combined recovery of these parameters, so additional assumptions are required, such as the Nordtvedt relationship η = 4β - γ - 3.We have modified our orbit determination software, GEODYN II, to enable the simultaneous integration of the spacecraft and central body trajectories. The combined estimation of the MESSENGER and Mercury orbits allowed us to determine a more accurate gravity field, orientation, and tides of Mercury, and the values of GM and J2 for the Sun, where G is the gravitational constant and M is the solar mass

  2. Return to Mercury: a global perspective on MESSENGER's first Mercury flyby.

    Science.gov (United States)

    Solomon, Sean C; McNutt, Ralph L; Watters, Thomas R; Lawrence, David J; Feldman, William C; Head, James W; Krimigis, Stamatios M; Murchie, Scott L; Phillips, Roger J; Slavin, James A; Zuber, Maria T

    2008-07-04

    In January 2008, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft became the first probe to fly past the planet Mercury in 33 years. The encounter revealed that Mercury is a dynamic system; its liquid iron-rich outer core is coupled through a dominantly dipolar magnetic field to the surface, exosphere, and magnetosphere, all of which interact with the solar wind. MESSENGER images confirm that lobate scarps are the dominant tectonic landform and record global contraction associated with cooling of the planet. The history of contraction can be related to the history of volcanism and cratering, and the total contractional strain is at least one-third greater than inferred from Mariner 10 images. On the basis of measurements of thermal neutrons made during the flyby, the average abundance of iron in Mercury's surface material is less than 6% by weight.

  3. Messenger RNA transcripts

    Science.gov (United States)

    Dan Cullen

    2004-01-01

    In contrast to DNA, messenger RNA (mRNA) in complex substrata is rarely analyzed, in large part because labile RNA molecules are difficult to purify. Nucleic acid extractions from fungi that colonize soil are particularly difficult and plagued by humic substances that interfere with Taq polymerase (Tebbe and Vahjen 1993 and references therein). Magnetic capture...

  4. Calcium in Mercury's Exosphere: Modeling MESSENGER Data

    Science.gov (United States)

    Burger, M. H.; Killen, R. M.; McClintock, W. E.; Merkel, A. W.; Vervack, R. J.; Sarantos, M.; Sprague, A. L.

    2011-12-01

    Mercury is surrounded by a surface-bounded exosphere known to contain hydrogen, sodium, potassium, calcium, and magnesium. Because the exosphere is collisionless, its composition represents a balance of active source and loss processes. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has made high-spatial-resolution observations of sodium, calcium, and magnesium near Mercury's surface and in the extended, anti-sunward direction. The most striking feature of these data is the substantial differences among species, which was detected during three close flybys of the planet and has been persistantly present during MESSENGER's orbital phase. Our modeling demonstrates that these differences are not because of post-ejection dynamics such as differences in photo-ionization rate and radiation pressure, but rather result from differences in the source mechanisms and regions on the surface from which each species is ejected. The observations of calcium have revealed a strong dawn/dusk asymmetry, with the abundance over the dawn hemisphere substantially greater than that on the dusk side. To understand this asymmetry, we use a Monte Carlo model of Mercury's exosphere that we developed to track the motions of exospheric neutrals under the influence of gravity and radiation pressure. In this model, Ca atoms can be ejected directly from the surface or produced by ejection of CaO followed by dissociation to produce Ca and O. Particles are removed from the system if they stick to the surface or escape from the model region of interest (within 15 Mercury radii). Photoionization reduces the final weighting given to each particle when simulating the Ca radiance. Data from the flybys are consistent with a high temperature (~1-2 x 104 K) source of atomic Ca concentrated over the dawn hemisphere. Such a high temperature resutls from dissociation of CaO in a near

  5. Insights into the Nature of Mercury's Exosphere: Early Results from the MESSENGER Orbital Mission Phase

    Science.gov (United States)

    McClintock, William E.; Burger, Matthew H.; Killen, Rosemary M.; Merkel, Aimee W.; Sarantos, Menelaos; Sprague, Ann L.; Solomon, Sean C.; Vervack, Ronald J., Jr.

    2011-01-01

    The Ultraviolet and Visible Spectrometer aboard the MESSENGER spacecraft has been making routine observations of Mercury's exosphere since March 29, 2011. Correlations of the spatial distributions of Ca, Mg, and Na with MESSENGER magnetic field and energetic particle distribution data provide insight into the processes that populate the neutral exosphere

  6. Diphosphoinositol Polyphosphates: Metabolic Messengers?

    Science.gov (United States)

    Shears, Stephen B.

    2009-01-01

    The diphosphoinositol polyphosphates (“inositol pyrophosphates”) are a specialized subgroup of the inositol phosphate signaling family. This review proposes that many of the current data concerning the metabolic turnover and biological effects of the diphosphoinositol polyphosphates are linked by a common theme: these polyphosphates act as metabolic messengers. This review will also discuss the latest proposals concerning possible molecular mechanisms of action of this intriguing class of molecules. PMID:19439500

  7. Performance Assessment of the Mercury Laser Altimeter on MESSENGER from Mercury Orbit

    Science.gov (United States)

    Sun, Xiaoli; Cavanaugh, John F.; Neumann, Gregory A.; Mazarico, Edward M.

    2009-01-01

    The Mercury Laser Altimeter (MLA) is one of seven instruments on the MErcury Surface, Space ENvironment GEochemistry, and Ranging (MESSENGER) spacecraft,a mission in NASA's Discovery Program. MESSENGER was launched on August 3, 2004, and entered into orbit about Mercury on March 29, 2011. As of June 30, 2011 MLA started to collect science Measurements on March 29, 2011. As of June 30, 2011 MLA had accumulated about 3 million laser ranging measurements to the Mercury surface through one Mercury year, i.e ., one complete cycle of the spacecraft thermal environment. The average MLA laser output-pulse energy remained steady despite the harsh thermal environment, in which the laser bench temperature changed by as much as 15 C over a 35 min operating period . The laser beam-collimating telescope experienced a 30 C temperature swing over the same period, and the thermal cycling repeated every 12 hours. Nonetheless, MLA receiver optics appeared to be aligned and in focus throughout these temperature excursions. The maximum ranging distance of MLA was 1500 km at near-zero laser-beam incidence angle (and emission angle) and 600 km at 60 deg incidence angle. The MLA instrument performance in Mercury orbit has been consistent with the performance demonstrated during MESSENGER's Mercury flybys in January and October 2008 and during pre-launch testing. In addition to range measurements, MLA data are being used to estimate the surface reflectance of Mercury at 1064 nm wavelength, including regions of permanent shadow on the floors of polar craters. MLA also provides a measurement of the surface reflectance of sunlight at 1064 nm wavelength by its noise counters, for which output is a monotonic function of the background light.

  8. Dynamical Messengers for Gauge Mediation

    Energy Technology Data Exchange (ETDEWEB)

    Hook, Anson; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.

    2011-08-17

    We construct models of indirect gauge mediation where the dynamics responsible for breaking supersymmetry simultaneously generates a weakly coupled subsector of messengers. This provides a microscopic realization of messenger gauge mediation where the messenger and hidden sector fields are unified into a single sector. The UV theory is SQCD with massless and massive quarks plus singlets, and at low energies it flows to a weakly coupled quiver gauge theory. One node provides the primary source of supersymmetry breaking, which is then transmitted to the node giving rise to the messenger fields. These models break R-symmetry spontaneously, produce realistic gaugino and sfermion masses, and give a heavy gravitino.

  9. Mercury's Na Exosphere from MESSENGER Data

    Science.gov (United States)

    Killen, Rosemary M.; Burger, M. H.; Cassidy, T. A.; Sarantos, M.; Vervack, R. J.; McClintock, W. El; Merkel, A. W.; Sprague, A. L.; Solomon, S. C.

    2012-01-01

    MESSENGER entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UWS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. Daily measurements of Na brightness were fitted with non-uniform exospheric models. With Monte Carlo sampling we traced the trajectories of a representative number of test particles, generally one million per run per source process, until photoionization, escape from the gravitational well, or permanent sticking at the surface removed the atom from the simulation. Atoms were assumed to partially thermally accommodate on each encounter with the surface with accommodation coefficient 0.25. Runs for different assumed source processes are run separately, scaled and co-added. Once these model results were saved onto a 3D grid, we ran lines of sight from the MESSENGER spacecraft :0 infinity using the SPICE kernels and we computed brightness integrals. Note that only particles that contribute to the measurement can be constrained with our method. Atoms and molecules produced on the nightside must escape the shadow in order to scatter light if the excitation process is resonant-light scattering, as assumed here. The aggregate distribution of Na atoms fits a 1200 K gas, with a PSD distribution, along with a hotter component. Our models constrain the hot component, assumed to be impact vaporization, to be emitted with a 2500 K Maxwellian. Most orbits show a dawnside enhancement in the hot component broadly spread over the leading hemisphere. However, on some dates there is no dawn/dusk asymmetry. The portion of the hot/cold source appears to be highly variable.

  10. In-Flight performance of MESSENGER's Mercury dual imaging system

    Science.gov (United States)

    Hawkins, S.E.; Murchie, S.L.; Becker, K.J.; Selby, C.M.; Turner, F.S.; Noble, M.W.; Chabot, N.L.; Choo, T.H.; Darlington, E.H.; Denevi, B.W.; Domingue, D.L.; Ernst, C.M.; Holsclaw, G.M.; Laslo, N.R.; Mcclintock, W.E.; Prockter, L.M.; Robinson, M.S.; Solomon, S.C.; Sterner, R.E.

    2009-01-01

    The Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 and planned for insertion into orbit around Mercury in 2011, has already completed two flybys of the innermost planet. The Mercury Dual Imaging System (MDIS) acquired nearly 2500 images from the first two flybys and viewed portions of Mercury's surface not viewed by Mariner 10 in 1974-1975. Mercury's proximity to the Sun and its slow rotation present challenges to the thermal design for a camera on an orbital mission around Mercury. In addition, strict limitations on spacecraft pointing and the highly elliptical orbit create challenges in attaining coverage at desired geometries and relatively uniform spatial resolution. The instrument designed to meet these challenges consists of dual imagers, a monochrome narrow-angle camera (NAC) with a 1.5?? field of view (FOV) and a multispectral wide-angle camera (WAC) with a 10.5?? FOV, co-aligned on a pivoting platform. The focal-plane electronics of each camera are identical and use a 1024??1024 charge-coupled device detector. The cameras are passively cooled but use diode heat pipes and phase-change-material thermal reservoirs to maintain the thermal configuration during the hot portions of the orbit. Here we present an overview of the instrument design and how the design meets its technical challenges. We also review results from the first two flybys, discuss the quality of MDIS data from the initial periods of data acquisition and how that compares with requirements, and summarize how in-flight tests are being used to improve the quality of the instrument calibration. ?? 2009 SPIE.

  11. Mercury after the Third MESSENGER Flyby

    Science.gov (United States)

    Solomon, S. C.; McNutt, R. L.; Bedini, P. D.; Anderson, B. J.; Evans, L. G.; Gold, R. E.; Head, J. W.; Krimigis, S. M.; Murchie, S. L.; Nittler, L.; Phillips, R. J.; Slavin, J. A.; Zuber, M. T.

    2009-12-01

    MESSENGER is the first spacecraft to visit the planet Mercury in more than 30 years. Images from MESSENGER’s first Mercury flyby, in January 2008, provided evidence for widespread volcanism, and candidate sites for volcanic centers were identified. Newly imaged lobate scarps and other tectonic landforms confirmed that Mercury contracted globally in response to interior cooling. The ~1500-km-diameter Caloris basin, viewed in its entirety for the first time by MESSENGER, was the focus for concentrations of volcanic centers, some with evidence of pyroclastic deposits, and widespread contractional and extensional deformation. Smooth plains interior and exterior to the basin are demonstrably younger than the basin-forming event. Reflectance spectra of Mercury’s surface showed no evidence for FeO in surface silicates. Reflectance and color imaging observations provided fresh support for earlier inferences that Mercury’s surface material consists dominantly of iron-poor, calcium-magnesium silicates with an admixture of spectrally neutral opaque minerals. MESSENGER’s second flyby, in October 2008, revealed the presence of neutral Mg and Ca in Mercury’s anti-sunward tail and documented strongly differing distributions of Mg, Ca, and Na in the nightside exosphere, the result of different combinations of time-variable source, transfer, and loss processes. A southward interplanetary magnetic field (IMF) was accompanied by multiple indications of magnetic reconnection at rates ~10 times typical at Earth; in combination with the more quiescent conditions under northward IMF seen during the first flyby, the results indicate that Mercury’s magnetosphere is more responsive to IMF direction than those of other planets. The internal magnetic field is dominantly dipolar with a vector moment closely aligned with the spin axis. The nearly global observations of Mercury surface units distinguishable by color and composition enforce the importance of the largely volcanic

  12. The rotational state of Mercury after four years of MESSENGER observations

    Science.gov (United States)

    Stark, Alexander; Oberst, Jürgen; Preusker, Frank; Hussmann, Hauke

    2017-04-01

    We measured the rotational state of Mercury with orbital data from NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. We use accurate co-registration of digital terrain models from stereo images (stereo DTMs) and laser altimeter data to measure the orientation of the rotation axis, the libration amplitude and the mean rotation rate with improved precision. In contrast to our previous study, we use the full four years of near-continuous Mercury Laser Altimeter (MLA) observations and stereo DTMs with a higher spatial coverage. We confirm a large libration amplitude and a mean rotation rate which is significantly higher than the assumed resonant rotation rate based on a perfect 3:2 spin orbit resonance. The estimated orientation of the rotation axis is consistent with the assumption that Mercury occupies a Cassini state. We compare our estimates with values based on Earth-based observations and MESSENGER radio science. Our results confirm that Mercury possesses a liquid outer core and we discuss further implications of our estimates on the interior structure of the planet.

  13. The Morphology of Craters on Mercury: Results from MESSENGER Flybys

    Science.gov (United States)

    Barnouin, Oliver S.; Zuber, Maria T.; Smith, David E.; Neumann, Gregory A.; Herrick, Robert R.; Chappelow, John E.; Murchie, Scott L.; Prockter, Louise M.

    2012-01-01

    Topographic data measured from the Mercury Laser Altimeter (MLA) and the Mercury Dual Imaging System (MDIS) aboard the MESSENGER spacecraft were used for investigations of the relationship between depth and diameter for impact craters on Mercury. Results using data from the MESSENGER flybys of the innermost planet indicate that most of the craters measured with MLA are shallower than those previously measured by using Mariner 10 images. MDIS images of these same MLA-measured craters show that they have been modified. The use of shadow measurement techniques, which were found to be accurate relative to the MLA results, indicate that both small bowl-shaped and large complex craters that are fresh possess depth-to-diameter ratios that are in good agreement with those measured from Mariner 10 images. The preliminary data also show that the depths of modified craters are shallower relative to fresh ones, and might provide quantitative estimates of crater in-filling by subsequent volcanic or impact processes. The diameter that defines the transition from simple to complex craters on Mercury based on MESSENGER data is consistent with that reported from Mariner 10 data.

  14. Nuclear Export of Messenger RNA

    Directory of Open Access Journals (Sweden)

    Jun Katahira

    2015-03-01

    Full Text Available Transport of messenger RNA (mRNA from the nucleus to the cytoplasm is an essential step of eukaryotic gene expression. In the cell nucleus, a precursor mRNA undergoes a series of processing steps, including capping at the 5' ends, splicing and cleavage/polyadenylation at the 3' ends. During this process, the mRNA associates with a wide variety of proteins, forming a messenger ribonucleoprotein (mRNP particle. Association with factors involved in nuclear export also occurs during transcription and processing, and thus nuclear export is fully integrated into mRNA maturation. The coupling between mRNA maturation and nuclear export is an important mechanism for providing only fully functional and competent mRNA to the cytoplasmic translational machinery, thereby ensuring accuracy and swiftness of gene expression. This review describes the molecular mechanism of nuclear mRNA export mediated by the principal transport factors, including Tap-p15 and the TREX complex.

  15. Spacecraft sterilization.

    Science.gov (United States)

    Kalfayan, S. H.

    1972-01-01

    Spacecraft sterilization is a vital factor in projects for the successful biological exploration of other planets. The microorganisms of major concern are the fungi and bacteria. Sterilization procedures are oriented toward the destruction of bacterial spores. Gaseous sterilants are examined, giving attention to formaldehyde, beta-propiolactone, ethylene oxide, and the chemistry of the bactericidal action of sterilants. Radiation has been seriously considered as another method for spacecraft sterilization. Dry heat sterilization is discussed together with the effects of ethylene oxide decontamination and dry heat sterilization on materials.

  16. MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus

    Science.gov (United States)

    Slavin, James A.; Acuna, Mario H.; Anderson, Brian J.; Barabash, Stas; Benna, Mehdi; Boardsen, Scott A.; Fraenz, Markus; Gloeckler, George; Gold, Robert E.; Ho,George C.; hide

    2009-01-01

    At 23:08 UTC on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude of 338 kin during its final flyby of Venus en route to its 2011 orbit insertion at Mercury. The availability of the simultaneous Venus Express solar wind and interplanetary magnetic field measurements provides a rare opportunity to examine the influence of upstream conditions on this planet's solar wind interaction. We present MESSENGER observations of new features of the Venus - solar wind interaction including hot flow anomalies upstream of the bow shock, a flux rope in the near-tail and a two-point determination of the timescale for magnetic flux transport through this induced magnetosphere. Citation: Stavin, J. A., et al. (2009), MESSENGER and Venus Express observations of the solar wind interaction with Venus,

  17. The Gravity Field of Mercury After the Messenger Low-Altitude Campaign

    Science.gov (United States)

    Mazarico, Erwan; Genova, Antonio; Goossens, Sander; Lemoine, Frank G.; Smith, David E.; Zuber, Maria T.; Neumann, Gary A.; Solomon, Sean C.

    2015-01-01

    The final year of the MESSENGER mission was designed to take advantage of the remaining propellant onboard to provide a series of lowaltitude observation campaigns and acquire novel scientific data about the innermost planet. The lower periapsis altitude greatly enhances the sensitivity to the short-wavelength gravity field, but only when the spacecraft is in view of Earth. After more than 3 years in orbit around Mercury, the MESSENGER spacecraft was tracked for the first time below 200-km altitude on 5 May 2014 by the NASA Deep Space Network (DSN). Between August and October, periapsis passages down to 25-km altitude were routinely tracked. These periods considerably improved the quality of the data coverage. Before the end of its mission, MESSENGER will fly at very low altitudes for extended periods of time. Given the orbital geometry, however the periapses will not be visible from Earth and so no new tracking data will be available for altitudes lower than 75 km. Nevertheless, the continuous tracking of MESSENGER in the northern hemisphere will help improve the uniformity of the spatial coverage at altitudes lower than 150 km, which will further improve the overall quality of the Mercury gravity field.

  18. MESSENGER SPICE KERNELS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes the complete set of MESSENGER SPICE data files (''kernel files''), which can be accessed using SPICE software. The SPICE data contains...

  19. Interplanetary Coronal Mass Ejections observed by MESSENGER and Venus Express

    CERN Document Server

    Good, S W

    2015-01-01

    Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER (MES) and Venus Express (VEX) spacecraft have been catalogued and analysed. The ICMEs were identified by a relatively smooth rotation of the magnetic field direction consistent with a flux rope structure, coinciding with a relatively enhanced magnetic field strength. A total of 35 ICMEs were found in the surveyed MES data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed VEX data (from May 2006 to December 2013). The ICME flux rope configurations have been determined. Ropes with northward leading edges were about four times more common than ropes with southward leading edges, in agreement with a previously established solar cycle dependence. Ropes with low inclinations to the solar equatorial plane were about four times more common than ropes with high inclinations, possibly an observational effect. Left and right-handed ropes were observed in almost equal numbers. In addition, data from MES, VEX, STEREO-A, STEREO-B ...

  20. Sweet spot supersymmetry and composite messengers

    OpenAIRE

    Ibe, Masahiro; Kitano, Ryuichiro

    2008-01-01

    Sweet spot supersymmetry is a phenomenologically and cosmologically perfect framework to realize a supersymmetric world at short distance. We discuss a class of dynamical models of supersymmetry breaking and its mediation whose low-energy effective description falls into this framework. Hadron fields in the dynamical models play a role of the messengers of the supersymmetry breaking. As is always true in the models of the sweet spot supersymmetry, the messenger scale is predicted to be 10^5 G...

  1. Anti-competitiveness of Instant Messenger Tying by Microsoft

    OpenAIRE

    Kim, Jaehong; Bang, Se Hoon; Hwang, Sunjoo

    2011-01-01

    In this paper, we theoretically analyze Microsoft's tying practice in the instant messenger market. Using a model that highlights distinct features of the instant messenger, which are different from the cases of the web browser and the media player, we show that Microsoft can leverage its monopoly power in the operating system (OS) market to the instant messenger market through tying strategy. Microsoft's messenger tying hurts consumers because it enables Microsoft to monopolize messenger mar...

  2. Spacecraft Cabin Particulate Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We have built and tested an optical extinction monitor for the detection of spacecraft cabin particulates. This sensor sensitive to particle sizes ranging from a few...

  3. Higgs mass from neutrino-messenger mixing

    Energy Technology Data Exchange (ETDEWEB)

    Byakti, Pritibhajan [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India); Department of Theoretical Physics, Indian Association for the Cultivation of Science,2A & 2B Raja S.C. Mullick Road, Kolkata 700 032 (India); Khosa, Charanjit K. [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India); Mummidi, V.S. [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India); Vempati, Sudhir K. [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India)

    2017-03-06

    The discovery of the Higgs particle at 125 GeV has put strong constraints on minimal messenger models of gauge mediation, pushing the stop masses into the multi-TeV regime. Extensions of these models with matter-messenger mixing terms have been proposed to generate a large trilinear parameter, A{sub t}, relaxing these constraints. The detailed survey of these models (DOI: 10.1007/JHEP05(2013)055; 10.1007/JHEP08(2013)093 ) so far considered messenger mixings with only MSSM superfields. In the present work, we extend the survey to MSSM with inverse-seesaw mechanism. The neutrino-sneutrino corrections to the Higgs mass in the inverse seesaw model are not significant in the minimal gauge mediation model, unless one considers messenger-matter interaction terms. We classify all possible models with messenger-matter interactions and perform thorough numerical analysis to find out the promising models. We found that out of the 17 possible models 9 of them can lead to Higgs mass within the observed value without raising the sfermion masses significantly. The successful models have stop masses ∼1.5 TeV with small or negligible mixing and yet a light CP even Higgs at 125 GeV.

  4. Sweet spot supersymmetry and composite messengers

    Science.gov (United States)

    Ibe, Masahiro; Kitano, Ryuichiro

    2008-05-01

    Sweet spot supersymmetry is a phenomenological effective Lagrangian of weak scale supersymmetry with a certain set of natural assumptions. This framework is designed to avoid problems in low-energy phenomenology and cosmology of supersymmetric models. We discuss a class of dynamical models of supersymmetry breaking and its mediation, whose low-energy effective description falls into this framework. Hadron fields in the dynamical models play a role of the messengers of the supersymmetry breaking. As is always true in the models of the sweet spot supersymmetry, the messenger scale is predicted to be 105 GeV ≲Mmess ≲1010 GeV. Various values of the effective number of messenger fields Nmess are possible depending on the choice of the gauge group.

  5. Students Engaging the Public in Exciting Discoveries by NASA's MESSENGER Mission

    Science.gov (United States)

    Hallau, K. G.; Morison, J.; Schuele, H.

    2012-12-01

    In March 2011, NASA's MESSENGER spacecraft entered into orbit around Mercury, the closest planet to the Sun. As the first mission to orbit and study Mercury in depth, MESSENGER sought to answer six primary scientific questions: why is Mercury so dense; what is the geologic history of Mercury; what is the nature of Mercury's magnetic field; what is the structure of Mercury's core; what are the unusual materials at Mercury's poles; and what volatiles are important at Mercury? In the first year of orbit, MESSENGER answered all of these questions, and also made several surprising discoveries. Student interns working with the MESSENGER Education and Public Outreach (EPO) team are using MESSENGER Mosaic Postcards (MPC) in both print and digital formats to present this new information to a broad audience. These MPCs, in conjunction with the rest of the MESSENGER EPO tools, present a unified and global resource for the public. By creating this resource in a variety of media, from printable cards to interactive features on the EPO website (http://www.messenger-education.org/), the EPO team can reach a larger audience, further the goal of the MPC project to share newly discovered features and phenomena with the general public, and thereby generate increased interest in and excitement about science and planetary exploration. One side of each MPC shows a MESSENGER image of a portion of Mercury's surface, and together the postcards can be arranged to form a complete image of the planet. On the reverse side of some cards is information pertaining to an item of interest in view on the image-side. One of us (physics undergraduate JEM) researches interesting features on the surface of Mercury and creates descriptions for the informational side of the postcards, and another (computer science undergraduate HCS) creates the digital versions of cards and associated resources for the Surface Interactive, an interactive tool on the MESSENGER EPO website. Postcards already in distribution

  6. Processivity and coupling in messenger RNA transcription.

    Directory of Open Access Journals (Sweden)

    Stuart Aitken

    2010-01-01

    Full Text Available The complexity of messenger RNA processing is now being uncovered by experimental techniques that are capable of detecting individual copies of mRNA in cells, and by quantitative real-time observations that reveal the kinetics. This processing is commonly modelled by permitting mRNA to be transcribed only when the promoter is in the on state. In this simple on/off model, the many processes involved in active transcription are represented by a single reaction. These processes include elongation, which has a minimum time for completion and processing that is not captured in the model.In this paper, we explore the impact on the mRNA distribution of representing the elongation process in more detail. Consideration of the mechanisms of elongation leads to two alternative models of the coupling between the elongating polymerase and the state of the promoter: Processivity allows polymerases to complete elongation irrespective of the promoter state, whereas coupling requires the promoter to be active to produce a full-length transcript. We demonstrate that these alternatives have a significant impact on the predicted distributions. Models are simulated by the Gillespie algorithm, and the third and fourth moments of the resulting distribution are computed in order to characterise the length of the tail, and sharpness of the peak. By this methodology, we show that the moments provide a concise summary of the distribution, showing statistically-significant differences across much of the feasible parameter range.We conclude that processivity is not fully consistent with the on/off model unless the probability of successfully completing elongation is low--as has been observed. The results also suggest that some form of coupling between the promoter and a rate-limiting step in transcription may explain the cell's inability to maintain high mRNA levels at low noise--a prediction of the on/off model that has no supporting evidence.

  7. Spacecraft design applications of QUICK

    Science.gov (United States)

    Skinner, David L.

    1992-01-01

    The interactive space mission trajectory design environment software QUICK, which is currently available on 14 different machine architectures, furnishes a programmable FORTRAN-like interface for a wide range of both built-in and user-defined functions. Since its inception at JPL in 1971, QUICK has evolved from a specialized calculator into a general-purpose engineering tool which also facilitates spacecraft conceptual design by treating spacecraft as collections of data records describing individual components of instruments.

  8. Intercultural Learning via Instant Messenger Interaction

    Science.gov (United States)

    Jin, Li; Erben, Tony

    2007-01-01

    This paper reports on a qualitative study investigating the viability of instant messenger (IM) interaction to facilitate intercultural learning in a foreign language class. Eight students in a Chinese as a foreign language (CFL) class participated in the study. Each student was paired with a native speaker (NS) of Chinese, and each pair…

  9. Messenger RNA surveillance: neutralizing natural nonsense

    DEFF Research Database (Denmark)

    Weischelfeldt, Joachim Lütken; Lykke-Andersen, Jens; Porse, Bo

    2005-01-01

    Messenger RNA transcripts that contain premature stop codons are degraded by a process termed nonsense-mediated mRNA decay (NMD). Although previously thought of as a pathway that rids the cell of non-functional mRNAs arising from mutations and processing errors, new research suggests a more general...

  10. 12 CFR 7.1012 - Messenger service.

    Science.gov (United States)

    2010-01-01

    ... section and appropriate to assure compliance with safe and sound banking practices. (c) Pick-up and... section and appropriate to assure compliance with safe and sound banking practices. (2) The OCC reviews...) The messenger service maintains ultimate responsibility for scheduling, movement, and routing; (iv...

  11. Multi-Messenger Astronomy with Gravitational Waves

    Indian Academy of Sciences (India)

    Sound + images show Bailey was out in the India-Australia match on 12 Jan 2016. Image credit: Rediff / Fox news / Twitter. Page 10. Electromagnetic follow up: the Indian context. Page 11. Multi-Messenger Astronomy with Gravitational Waves | LIGO-G1601377-v2. Varun Bhalerao (IUCAA) | 1 July 2016. 11. 20 – 60 keV:.

  12. FSD- FLEXIBLE SPACECRAFT DYNAMICS

    Science.gov (United States)

    Fedor, J. V.

    1994-01-01

    The Flexible Spacecraft Dynamics and Control program (FSD) was developed to aid in the simulation of a large class of flexible and rigid spacecraft. FSD is extremely versatile and can be used in attitude dynamics and control analysis as well as in-orbit support of deployment and control of spacecraft. FSD has been used to analyze the in-orbit attitude performance and antenna deployment of the RAE and IMP class satellites, and the HAWKEYE, SCATHA, EXOS-B, and Dynamics Explorer flight programs. FSD is applicable to inertially-oriented spinning, earth oriented, or gravity gradient stabilized spacecraft. The spacecraft flexibility is treated in a continuous manner (instead of finite element) by employing a series of shape functions for the flexible elements. Torsion, bending, and three flexible modes can be simulated for every flexible element. FSD can handle up to ten tubular elements in an arbitrary orientation. FSD is appropriate for studies involving the active control of pointed instruments, with options for digital PID (proportional, integral, derivative) error feedback controllers and control actuators such as thrusters and momentum wheels. The input to FSD is in four parts: 1) Orbit Construction FSD calculates a Keplerian orbit with environmental effects such as drag, magnetic torque, solar pressure, thermal effects, and thruster adjustments; or the user can supply a GTDS format orbit tape for a particular satellite/time-span; 2) Control words - for options such as gravity gradient effects, control torques, and integration ranges; 3) Mathematical descriptions of spacecraft, appendages, and control systems- including element geometry, properties, attitudes, libration damping, tip mass inertia, thermal expansion, magnetic tracking, and gimbal simulation options; and 4) Desired state variables to output, i.e., geometries, bending moments, fast Fourier transform plots, gimbal rotation, filter vectors, etc. All FSD input is of free format, namelist construction. FSD

  13. Do not shoot the messenger

    DEFF Research Database (Denmark)

    Ballesteros, Marta; Chapela, Rosa; Monsalve, Maria Paulina Ramirez

    2017-01-01

    to be far from a fully functional operational framework. To what extent availability of appropriate scientific advice is a barrier for a more widespread use of an EAFM in Europe remains an open question. Building on the findings of a large research project, this article explores what advice ICES can provide....... The article concludes that: (i) ICES has taken a leading role in generating an EAFM framework in which management decisions can operate; (ii) the advice “suppliers” and the advice “users” agree on the feasibility of using existing knowledge to “do EAFM now”; (iii) ICES can address a range of shortcomings...

  14. Spacecraft Thermal Management

    Science.gov (United States)

    Hurlbert, Kathryn Miller

    2009-01-01

    In the 21st century, the National Aeronautics and Space Administration (NASA), the Russian Federal Space Agency, the National Space Agency of Ukraine, the China National Space Administration, and many other organizations representing spacefaring nations shall continue or newly implement robust space programs. Additionally, business corporations are pursuing commercialization of space for enabling space tourism and capital business ventures. Future space missions are likely to include orbiting satellites, orbiting platforms, space stations, interplanetary vehicles, planetary surface missions, and planetary research probes. Many of these missions will include humans to conduct research for scientific and terrestrial benefits and for space tourism, and this century will therefore establish a permanent human presence beyond Earth s confines. Other missions will not include humans, but will be autonomous (e.g., satellites, robotic exploration), and will also serve to support the goals of exploring space and providing benefits to Earth s populace. This section focuses on thermal management systems for human space exploration, although the guiding principles can be applied to unmanned space vehicles as well. All spacecraft require a thermal management system to maintain a tolerable thermal environment for the spacecraft crew and/or equipment. The requirements for human rating and the specified controlled temperature range (approximately 275 K - 310 K) for crewed spacecraft are unique, and key design criteria stem from overall vehicle and operational/programatic considerations. These criteria include high reliability, low mass, minimal power requirements, low development and operational costs, and high confidence for mission success and safety. This section describes the four major subsystems for crewed spacecraft thermal management systems, and design considerations for each. Additionally, some examples of specialized or advanced thermal system technologies are presented

  15. Multi-messenger aspects of cosmic neutrinos*

    Directory of Open Access Journals (Sweden)

    Ahlers Markus

    2016-01-01

    Full Text Available The recent observation of TeV-PeV neutrinos by IceCube has opened a new window to the high-energy Universe. I will discuss this signal in the context of multi-messenger astronomy. For extragalactic source scenarios the corresponding gamma-rays are not directly observable due to interactions with the cosmic radiation backgrounds. Nevertheless, the isotropic sub-TeV gamma ray background observed by Fermi-LAT contains indirect information from secondary emission produced in electromagnetic cascades. On the other hand, observation of PeV gamma rays would provide a smoking-gun signal for Galactic emission. Interestingly, the overall energy density of the observed neutrino flux is close to a theoretical limit for neutrino production in ultra-high energy cosmic ray sources and might indicate a common origin of these phenomena. I will highlight various multi-messenger relations and their implications for neutrino source scenarios.

  16. The Energy Messenger, Number 1, Volume 4

    Energy Technology Data Exchange (ETDEWEB)

    Stancil, J. [ed.

    1995-01-01

    `The Energy Messenger` is a Department of Energy publication on energy activities of interest to American Indians. The first issue of 1995 (in a magazine format) includes articles on: tribes winning grants to develop energy resources, recruiting of internships for DOE, information about Title XXVI-Indian Energy Resources, American Indian Heritage Month, tribal perspective on DOE actions, joint ventures between tribes and the DOE, and brief description of recent DOE activities.

  17. Review Essay: Lacan, via Messenger

    Directory of Open Access Journals (Sweden)

    Achim Seiffarth

    2006-05-01

    Full Text Available We'll never know what LACAN really said. The various editions of his works are only partly authorized by LACAN himself, and the few critical editions are not among those that are. Anyone who wants to learn about the Master's thought has to study influences, transmissions, and the trajectories of words and texts ascribed to LACAN. The contributors to this volume by THOLEN, SCHMITZ and RIEPE focus on the three themes nominated in the book's title. Some primarily discuss the role of transfer in psychoanalysis, others critically examine German translations of the Master's texts, and a third group studies the emergence of a psychoanalytic tradition. We might affirm that all the articles represent the three T's together: practising transfer, translating what might otherwise be incomprehensible, and constituting tradition. But this is a bond too weak to connect the various works presented in THOLEN, SCHMITZ and RIEPE's book. In fact, the book seems to explode. The range of topics treated by the authors reaches far beyond any disciplinary border and includes themes as different as dysgraphia and dyslexia, interpretations of HÖLDERLIN, BENJAMIN and KAFKA, the legal definition of death, theory of mass communication, the history of psychology, and the diffusion of psychoanalysis in Europe (Italy, Austria, Belgium and Ireland. As a consequence, reading the mostly well written and stimulating articles one after the other might be slightly irritating. "Transfer—Translation—Tradition" is an interesting book, though it's not really a book at all. This kind of successful failure probably is LACANian heritage (even if, yes, we've heard that story from Bob DYLAN, too. URN: urn:nbn:de:0114-fqs0603156

  18. Benefits of Spacecraft Level Vibration Testing

    Science.gov (United States)

    Gordon, Scott; Kern, Dennis L.

    2015-01-01

    NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

  19. Mercury's Solar Wind Interaction as Characterized by Magnetospheric Plasma Mantle Observations With MESSENGER

    Science.gov (United States)

    Jasinski, Jamie M.; Slavin, James A.; Raines, Jim M.; DiBraccio, Gina A.

    2017-12-01

    We analyze 94 traversals of Mercury's southern magnetospheric plasma mantle using data from the MESSENGER spacecraft. The mean and median proton number densities in the mantle are 1.5 and 1.3 cm-3, respectively. For sodium number density these values are 0.004 and 0.002 cm-3. Moderately higher densities are observed on the magnetospheric dusk side. The mantle supplies up to 1.5 × 108 cm-2 s-1 and 0.8 × 108 cm-2 s-1 of proton and sodium flux to the plasma sheet, respectively. We estimate the cross-electric magnetospheric potential from each observation and find a mean of 19 kV (standard deviation of 16 kV) and a median of 13 kV. This is an important result as it is lower than previous estimations and shows that Mercury's magnetosphere is at times not as highly driven by the solar wind as previously thought. Our values are comparable to the estimations for the ice giant planets, Uranus and Neptune, but lower than Earth. The estimated potentials do have a very large range of values (1-74 kV), showing that Mercury's magnetosphere is highly dynamic. A correlation of the potential is found to the interplanetary magnetic field (IMF) magnitude, supporting evidence that dayside magnetic reconnection can occur at all shear angles at Mercury. But we also see that Mercury has an Earth-like magnetospheric response, favoring -BZ IMF orientation. We find evidence that -BX orientations in the IMF favor the southern cusp and southern mantle. This is in agreement with telescopic observations of exospheric emission, but in disagreement with modeling.

  20. Calibration, Projection, and Final Image Products of MESSENGER's Mercury Dual Imaging System

    Science.gov (United States)

    Denevi, Brett W.; Chabot, Nancy L.; Murchie, Scott L.; Becker, Kris J.; Blewett, David T.; Domingue, Deborah L.; Ernst, Carolyn M.; Hash, Christopher D.; Hawkins, S. Edward; Keller, Mary R.; Laslo, Nori R.; Nair, Hari; Robinson, Mark S.; Seelos, Frank P.; Stephens, Grant K.; Turner, F. Scott; Solomon, Sean C.

    2018-02-01

    We present an overview of the operations, calibration, geodetic control, photometric standardization, and processing of images from the Mercury Dual Imaging System (MDIS) acquired during the orbital phase of the MESSENGER spacecraft's mission at Mercury (18 March 2011-30 April 2015). We also provide a summary of all of the MDIS products that are available in NASA's Planetary Data System (PDS). Updates to the radiometric calibration included slight modification of the frame-transfer smear correction, updates to the flat fields of some wide-angle camera (WAC) filters, a new model for the temperature dependence of narrow-angle camera (NAC) and WAC sensitivity, and an empirical correction for temporal changes in WAC responsivity. Further, efforts to characterize scattered light in the WAC system are described, along with a mosaic-dependent correction for scattered light that was derived for two regional mosaics. Updates to the geometric calibration focused on the focal lengths and distortions of the NAC and all WAC filters, NAC-WAC alignment, and calibration of the MDIS pivot angle and base. Additionally, two control networks were derived so that the majority of MDIS images can be co-registered with sub-pixel accuracy; the larger of the two control networks was also used to create a global digital elevation model. Finally, we describe the image processing and photometric standardization parameters used in the creation of the MDIS advanced products in the PDS, which include seven large-scale mosaics, numerous targeted local mosaics, and a set of digital elevation models ranging in scale from local to global.

  1. Gravitational Waves and Multi-Messenger Astronomy

    Science.gov (United States)

    Centrella, Joan M.

    2010-01-01

    Gravitational waves are produced by a wide variety of sources throughout the cosmos, including the mergers of black hole and neutron star binaries/compact objects spiraling into central black holes in galactic nuclei, close compact binaries/and phase transitions and quantum fluctuations in the early universe. Observing these signals can bring new, and often very precise, information about their sources across vast stretches of cosmic time. In this talk we will focus on thee opening of this gravitational-wave window on the universe, highlighting new opportunities for discovery and multi-messenger astronomy.

  2. The Exploration of Mercury by MESSENGER: Looking Ahead to Orbital Observations

    Science.gov (United States)

    Solomon, S. C.; McNutt, R. L.; Bedini, P. D.; Anderson, B. J.; Prockter, L. M.; Blewett, D. T.; Evans, L. G.; Gold, R. E.; Krimigis, S. M.; Murchie, S. L.; Nittler, L. R.; Phillips, R. J.; Slavin, J. A.; Zuber, M. T.

    2010-12-01

    NASA's MESSENGER spacecraft flew by Mercury three times in 2008-09 en route to insertion into orbit about the planet in March 2011. The flybys confirmed that the planet's internal magnetic field is dominantly dipolar, with a vector moment closely aligned with the spin axis. MESSENGER detected Mg and Ca+ in Mercury’s exosphere, demonstrated that Mercury's anti-sunward neutral tail contains multiple species, and revealed that exospheric Na, Ca, and Mg vary differently with space and time, signatures of multiple source processes. MESSENGER's laser altimeter showed that the equatorial topographic relief of Mercury exceeds 5 km, revealed an equatorial ellipticity aligned with the ellipticity in Mercury's gravitational potential, and profiled numerous impact craters and fault scarps. MESSENGER images provided evidence for widespread volcanism, and candidate sites for volcanic centers were identified. Newly imaged lobate scarps and other tectonic landforms support the hypothesis that Mercury contracted globally in response to interior cooling. The ˜1500-km-diameter Caloris basin was a focus for volcanic centers, some with evidence of pyroclastic deposits, and widespread contractional and extensional deformation; smooth plains interior and exterior to the basin postdate the basin-forming event. The interior plains of the ˜290-km-diameter Rachmaninoff basin are among the youngest volcanic material on the planet. Mercury surface units are distinguishable by color and composition; smooth plains occupy ˜40% of the surface area, and low-reflectance material occupies ˜15% of the surface area and is primarily seen in deposits excavated by impact. Reflectance spectra show no evidence for FeO in surface silicates, and reflectance and color imaging observations support the view that Mercury's surface material consists dominantly of Fe-poor, Ca-Mg silicates with an admixture of spectrally neutral opaque minerals. In support of the hypothesis that those opaque minerals are Fe

  3. Interplanetary Magnetic Field Power Spectrum Variations in the Inner Heliosphere: A Wind and MESSENGER Study

    Science.gov (United States)

    Szabo, Adam; Koval, A.

    2011-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the similar observations made by the MESSENGER spacecraft in the inner heliosphere affords an opportunity to compare magnetic field power spectral density variations as a function of radial distance from the Sun under different solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The powe'r spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. Wind and MESSENGER magnetic fluctuations are compared for times when the two spacecraft are close to radial and Parker field alignment. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

  4. Mars Observer spacecraft

    Science.gov (United States)

    Potts, Dennis L.

    1989-01-01

    The technical aspects of the spacecraft for the Mars Observer mission are discussed. The spacecraft development focuses on using existing flight subsystem designs and production techniques to offer a low-cost, reliable, production-type spacecraft. The scientific objectives of the mission and the scientific payloads of the spacecraft are considered. The spacecraft system and its performance are discussed. The subsystems are described in detail, including attitude and articulation control, electrical power supply, propulsion, structure, thermal control, command and data handling, telecommunications, mechanics, and flight software.

  5. PEMBUATAN SYSTEM CORPORATE MESSENGER PADA JARINGAN LAN

    Directory of Open Access Journals (Sweden)

    Lily Puspa Dewi

    2008-01-01

    Full Text Available Corporate messenger is the one of the application that can be used for communication in a local area network. The backgrounds of this topic are needs of sending message process in the LAN. The messages which want to be presented are not only in a text format, but also can be in audio visual format. Computer client will connect to the server. When the connection has been established, the client continued the authentication and started sending message between client and server. Audio and video message sending can be done with peer to peer connection with entering the IP address first from remote user that we want to communicate with. The evaluation of this application was done by using 3 computers and as the result, we found that authentication process can work properly, sending text message was done properly and communication using audio can be heard clearly. In addition to video sending message, we could see directly in remote client. The average time to show the video on remote client is 3.771 seconds. Abstract in Bahasa Indonesia: Corporate messenger merupakan suatu aplikasi yang dapat digunakan untuk berkomunikasi dalam sebuah Local Area Network. Hal ini dilatarbelakangi oleh perlu adanya proses pengiriman pesan secara bersama-sama dalam sebuah Local Area Network. Pesan yang ingin dikomunikasikan tidak hanya berupa teks, tetapi dapat juga menggunakan video maupun audio Komputer client akan melakukan koneksi dengan server. Jika sudah terjadi koneksi dengan server, maka client tersebut akan melanjutkan dengan autentikasi dan kemudian dapat melakukan pengiriman pesan dengan client yang telah terdaftar dalam database server. Pengiriman pesan audio dan video terjadi dengan koneksi peer to peer dengan terlebih dahulu memasukkan IP address dari remote user yang ingin diajak berkomunikasi. Pengujian dilakukan dengan menggunakan tiga buah komputer dan diperoleh bahwa proses autentikasi dapat berjalan dengan baik, pengiriman pesan teks dapat dilakukan

  6. [Irisin: a messenger from the gods?].

    Science.gov (United States)

    Moreno, María; Moreno-Navarrete, José María; Fernández-Real, José Manuel

    2014-01-01

    Due to the need to understand the basis of the metabolic benefits of exercise, irisin was discovered a few years ago. This cytokine, secreted by skeletal muscle due to exercise, should have positive effects on energetic metabolism. In particular, it could act as a messenger on white adipose tissue, modifying its phenotype into the beige adipocyte, and increasing its thermogenic capacity. Since it was described, there have been numerous studies led to depict its function, with the aim of determining if irisin could become a therapeutic target in the context of diseases associated with a caloric excess, such as obesity and diabetes. In this review, the irisin discovery is summarized, along with its in vitro and in vivo effects described up until now. Copyright © 2013 Sociedad Española de Arteriosclerosis. Published by Elsevier España. All rights reserved.

  7. Emerging roles in plant biotechnology for the second messenger ...

    African Journals Online (AJOL)

    Second messengers are small transient molecules that transmit and/or modulate environmental or hormonal signals linking them to complex and often systemic physiological responses. Recent reports have renewed interest in the second messenger guanosine 3', 5'-cyclic monophosphate (cGMP) since it has been shown ...

  8. Spacecraft Spin Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides the capability to correct unbalances of spacecraft by using dynamic measurement techniques and static/coupled measurements to provide products of...

  9. A Ross-Stirling spacecraft refrigerator

    Science.gov (United States)

    Walker, G.; Scott, M.; Zylstra, S.

    A spacecraft refrigerator was investigated capable of providing cooling for storage of food and biological samples in the temperature range 0-20 F with cooling capacity in the range of 1 to 2 kW, operating for long periods with great reliability. The system operated on the Stirling refrigeration cycle using the spacecraft life-support gases as the working fluid. A prototype spacecraft Stirling refrigerator was designed, built, and tested with air as the working fluid. The system performance was satisfactory, meeting the requirements specified above. Potential applications for the prototype unit are mentioned.

  10. Comparative analysis of planetary laser ranging concepts

    Science.gov (United States)

    Dirkx, D.; Bauer, S.; Noomen, R.; Vermeersen, B. L. A.; Visser, P. N.

    2014-12-01

    Laser ranging is an emerging technology for tracking interplanetary missions, offering improved range accuracy and precision (mm-cm), compared to existing DSN tracking. The ground segment uses existing Satellite Laser Ranging (SLR) technology, whereas the space segment is modified with an active system. In a one-way system, such as that currently being used on the LRO spacecraft (Zuber et al., 2010), only an active detector is required on the spacecraft. For a two-way system, such as that tested by using the laser altimeter system on the MESSENGER spacecraft en route to Mercury (Smith et al., 2006), a laser transmitter system is additionally placed on the space segment, which will asynchronously fire laser pulses towards the ground stations. Although the one-way system requires less hardware, clock errors on both the space and ground segments will accumulate over time, polluting the range measurements. For a two-way system, the range measurements are only sensitive to clock errors integrated over the the two-way light time.We investigate the performance of both one- and two-way laser range systems by simulating their operation. We generate realizations of clock error time histories from Allan variance profiles, and use them to create range measurement error profiles. We subsequently perform the orbit determination process from this data to quanitfy the system's performance. For our simulations, we use two test cases: a lunar orbiter similar to LRO and a Phobos lander similar to the Phobos Laser Ranging concept (Turyshev et al., 2010). For the lunar orbiter, we include an empirical model for unmodelled non-gravitational accelerations in our truth model to include errors ihe dynamics. We include the estimation of clock parameters over a number of arc lengths for our simulations of the one-way range system and use a variety of state arc durations for the lunar orbiter simulations.We perform Monte Carlo simulations and generate true error distributions for both

  11. Toward high-resolution global topography of Mercury from MESSENGER orbital stereo imaging: A prototype model for the H6 (Kuiper) quadrangle

    Science.gov (United States)

    Preusker, Frank; Stark, Alexander; Oberst, Jürgen; Matz, Klaus-Dieter; Gwinner, Klaus; Roatsch, Thomas; Watters, Thomas R.

    2017-08-01

    We selected approximately 10,500 narrow-angle camera (NAC) and wide-angle camera (WAC) images of Mercury acquired from orbit by MESSENGER's Mercury Dual Imaging System (MDIS) with an average resolution of 150 m/pixel to compute a digital terrain model (DTM) for the H6 (Kuiper) quadrangle, which extends from 22.5°S to 22.5°N and from 288.0°E to 360.0°E. From the images, we identified about 21,100 stereo image combinations consisting of at least three images each. We applied sparse multi-image matching to derive approximately 250,000 tie-points representing 50,000 ground points. We used the tie-points to carry out a photogrammetric block adjustment, which improves the image pointing and the accuracy of the ground point positions in three dimensions from about 850 m to approximately 55 m. We then applied high-density (pixel-by-pixel) multi-image matching to derive about 45 billion tie-points. Benefitting from improved image pointing data achieved through photogrammetric block adjustment, we computed about 6.3 billion surface points. By interpolation, we generated a DTM with a lateral spacing of 221.7 m/pixel (192 pixels per degree) and a vertical accuracy of about 30 m. The comparison of the DTM with Mercury Laser Altimeter (MLA) profiles obtained over four years of MESSENGER orbital operations reveals that the DTM is geometrically very rigid. It may be used as a reference to identify MLA outliers (e.g., when MLA operated at its ranging limit) or to map offsets of laser altimeter tracks, presumably caused by residual spacecraft orbit and attitude errors. After the relevant outlier removals and corrections, MLA profiles show excellent agreement with topographic profiles from H6, with a root mean square height difference of only 88 m.

  12. Venus upper clouds and the UV-absorber from MESSENGER/MASCS observations

    Science.gov (United States)

    Perez-Hoyos, Santiago; Sanchez-Lavega, Agustin; Garcia Munoz, Antonio; Irwin, Patrick; Peralta, Javier; Holsclaw, Greg; McClintock, William

    2014-11-01

    In June 2007, the MESSENGER spacecraft performed its second Venus flyby on its route to Mercury. The spacecraft’s MASCS instrument (VIRS channel) acquired numerous spectra of the sunlight reflected from the equatorial region of the planet at wavelengths from the near ultraviolet (300nm) to the near infrared (1450 nm). In this work we present an analysis of the data and their spectral and spatial variability following the mission footprint on the Venus disk. In order to reproduce the observed reflectivity and obtain information on the upper clouds and the unknown UV absorber, we use the NEMESIS retrieval code, including SO2 , CO2 and H2O absorption together with absorption and scattering by mode-1, -2 and -3 cloud particles. This spectral range provides sensitivity to the uppermost cloud levels, above 60 km. Vertical profiles of the mode-1 and mode-2 particles have been retrieved along the equatorial region of Venus, with average retrieved sounding levels of 70 +/- 2 km at 1 micron, in good agreement with previous investigations. This spectral range is also very interesting because of the existence of a mysterious absorber in the blue and UV side of the reflected spectra, whose origin remains as one of the key questions about the Venus atmosphere. Here we report a comparison with some of the previously proposed absorbers: (1) sulfur-related compounds (amorphous and liquid sulfur, S3, S4, S8, S2O); (2) chlorine related species (Cl2, FeCl3); (3) organics (C3O2, Croconic acid). Preliminary results show that the first group provides better fits to the data, although combinations of the proposed agents might be required in order to produce better results. Acknowledgements: This work was supported by the Spanish MICIIN projects AYA2009- 10701, AYA2012-38897-C02-01, and AYA2012-36666 with FEDER support, PRICIT-S2009/ESP-1496, Grupos Gobierno Vasco IT765-13, and UPV/EHU UFI11/55. S.P.-H. acknowledges support from the Jose Castillejo Program funded by Ministerio de Educaci

  13. Current LISA Spacecraft Design

    Science.gov (United States)

    Merkowitz, S. M.; Castellucci, K. E.; Depalo, S. V.; Generie, J. A.; Maghami, P. G.; Peabody, H. L.

    2009-01-01

    The Laser Interferometer Space Antenna (LISA) mission. a space based gravitational wave detector. uses laser metrology to measure distance fluctuations between proof masses aboard three spacecraft. LISA is unique from a mission design perspective in that the three spacecraft and their associated operations form one distributed science instrument. unlike more conventional missions where an instrument is a component of an individual spacecraft. The design of the LISA spacecraft is also tightly coupled to the design and requirements of the scientific payload; for this reason it is often referred to as a "sciencecraft." Here we describe some of the unique features of the LISA spacecraft design that help create the quiet environment necessary for gravitational wave observations.

  14. Current LISA spacecraft design

    Energy Technology Data Exchange (ETDEWEB)

    Merkowitz, S M; Castellucci, K E; Depalo, S V; Generie, J A; Maghami, P G; Peabody, H L, E-mail: Stephen.M.Merkowitz@nasa.go [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2009-03-01

    The Laser Interferometer Space Antenna (LISA) mission, a space based gravitational wave detector, uses laser metrology to measure distance fluctuations between proof masses aboard three spacecraft. LISA is unique from a mission design perspective in that the three spacecraft and their associated operations form one distributed science instrument, unlike more conventional missions where an instrument is a component of an individual spacecraft. The design of the LISA spacecraft is also tightly coupled to the design and requirements of the scientific payload; for this reason it is often referred to as a 'sciencecraft'. Here we describe some of the unique features of the LISA spacecraft design that help create the quiet environment necessary for gravitational wave observations.

  15. MESSENGER MERCURY RSS/MLA LEVEL 5 DERIVED DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains archival results from radio science investigations conducted during the MESSENGER mission. Radio measurements were made using the MESSENGER...

  16. Key science issues after MESSENGER and current observation plans of BepiColombo MMO

    Science.gov (United States)

    Murakami, Go; Hayakawa, Hajime; Fujimoto, Masaki

    2017-04-01

    Little had been known about the Hermean magnetosphere until MESSENGER explored the region. The region is formed as the weak planetary magnetic field stands against the intense solar wind in the close proximity of the Sun. Various prediction had been given by noting the difference in the parameters from the well-studied terrestiral magnetosphere of a similar setting and scaling the well-knowns to the Hermean environment. MESSENGER results, however, show a wide varieity of phenomena that are out of the scope of what one could have reasonably argued. The micro-magnetosphere of Mercury is much more dynamic than one had predicted. BepiColombo MMO, the JAXA spacecraft of the BepiColombo Mercury exploration mission which will be launched in 2018 and will arrive at Mercury in 2025, is equipped to study the space environment of the planet Mercury. BepiColombo MMO is mainly designed for plasma observations and is expected to extract essential elements of space plasma physics that become visible in the Hermean environment. MMO has large constraints on science operations, such as thermal issue and limited telemetry rate. Due to the thermal issue each science instrument cannot always be turned on. In addition, due to the low telemetry rate in average, only a part ( 20-30%) of science mission data with high resolution can be downlinked. Therefore, in order to maximize the scientific results and outcomes to be achieved by MMO, we are now working to optimize the science observation and downlink plans in detail. Here we review MESSENGER results and how MMO will contribute to deepen our understanding of space plasmas by addressing the puzzles raised by MESSEGNER.

  17. Spacecraft Formation Orbit Estimation Using WLPS-Based Localization

    Directory of Open Access Journals (Sweden)

    Shu Ting Goh

    2011-01-01

    Full Text Available This paper studies the implementation of a novel wireless local positioning system (WLPS for spacecraft formation flying to maintain high-performance spacecraft relative and absolute position estimation. A WLPS equipped with antenna arrays allows each spacecraft to measure the relative range and coordinate angle(s of other spacecraft located in its coverage area. The dynamic base station and the transponder of WLPS enable spacecraft to localize each other in the formation. Because the signal travels roundtrip in WLPS, and due to the high spacecraft velocities, the signal transmission time delay reduces the localization performance. This work studies spacecraft formation positions estimation performance assuming that only WLPS is available onboard. The feasibility of estimating the spacecraft absolute position using only one-dimensional antenna array is also investigated. The effect of including GPS measurements in addition to WLPS is studied and compared to a GPS standalone system.

  18. Spacecraft Tests of General Relativity

    Science.gov (United States)

    Anderson, John D.

    1997-01-01

    Current spacecraft tests of general relativity depend on coherent radio tracking referred to atomic frequency standards at the ground stations. This paper addresses the possibility of improved tests using essentially the current system, but with the added possibility of a space-borne atomic clock. Outside of the obvious measurement of the gravitational frequency shift of the spacecraft clock, a successor to the suborbital flight of a Scout D rocket in 1976 (GP-A Project), other metric tests would benefit most directly by a possible improved sensitivity for the reduced coherent data. For purposes of illustration, two possible missions are discussed. The first is a highly eccentric Earth orbiter, and the second a solar-conjunction experiment to measure the Shapiro time delay using coherent Doppler data instead of the conventional ranging modulation.

  19. Compact Imagers Based on MESSENGER's Mercury Dual Imaging System

    Science.gov (United States)

    Chabot, N. L.; Murchie, S. L.; Hawkins, S. E.; Hayes, J. R.; Boldt, J. D.; Barnouin, O. S.; Heffernan, K.; Noble, M. W.

    2012-10-01

    MESSENGER's Mercury Dual Imaging System (MDIS) has acquired >130,000 images since launch in 2004, including the first images from Mercury orbit. MDIS, composed of two miniature cameras, has capabilities well matched to future planetary missions.

  20. MESSENGER observations of the composition of Mercury's ionized exosphere and plasma environment.

    Science.gov (United States)

    Zurbuchen, Thomas H; Raines, Jim M; Gloeckler, George; Krimigis, Stamatios M; Slavin, James A; Koehn, Patrick L; Killen, Rosemary M; Sprague, Ann L; McNutt, Ralph L; Solomon, Sean C

    2008-07-04

    The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na+, O+, and K+ abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S+ and H2S+, with (S+ + H2S+)/(Na+ + Mg+) = 0.67 +/- 0.06, and from water-group ions around m/q = 18, at an abundance of 0.20 +/- 0.03 relative to Na+ plus Mg+. The fluxes of Na+, O+, and heavier ions are largest near the planet, but these Mercury-derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere.

  1. Spacecraft Material Outgassing Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This compilation of outgassing data of materials intended for spacecraft use were obtained at the Goddard Space Flight Center (GSFC), utilizing equipment developed...

  2. Spacecraft Power Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project will develop the Spacecraft Power Monitor (SPM) which will use non-intrusive electrical monitoring (NEMO). NEMO transforms the power...

  3. Spacecraft momentum control systems

    CERN Document Server

    Leve, Frederick A; Peck, Mason A

    2015-01-01

    The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented ...

  4. World manned spacecraft characteristics

    Science.gov (United States)

    Wade, M.

    1981-10-01

    Statistical data on manned spacecraft that have flown or will fly in the immediate future are presented. It is thought that this information has not been brought together before. Gemini is described as being the most spacecraft in the smallest package. In discussing Soyuz, special attention is given to the role played by the orbital module concept. Descriptions are also given of the Voskhod, Dynosaurs, and the Mercury-type capsule that will be used by Chinese astronauts.

  5. Internet Access to Spacecraft

    Science.gov (United States)

    Rash, James; Parise, Ron; Hogie, Keith; Criscuolo, Ed; Langston, Jim; Jackson, Chris; Price, Harold; Powers, Edward I. (Technical Monitor)

    2000-01-01

    The Operating Missions as Nodes on the Internet (OMNI) project at NASA's Goddard Space flight Center (GSFC), is demonstrating the use of standard Internet protocols for spacecraft communication systems. This year, demonstrations of Internet access to a flying spacecraft have been performed with the UoSAT-12 spacecraft owned and operated by Surrey Satellite Technology Ltd. (SSTL). Previously, demonstrations were performed using a ground satellite simulator and NASA's Tracking and Data Relay Satellite System (TDRSS). These activities are part of NASA's Space Operations Management Office (SOMO) Technology Program, The work is focused on defining the communication architecture for future NASA missions to support both NASA's "faster, better, cheaper" concept and to enable new types of collaborative science. The use of standard Internet communication technology for spacecraft simplifies design, supports initial integration and test across an IP based network, and enables direct communication between scientists and instruments as well as between different spacecraft, The most recent demonstrations consisted of uploading an Internet Protocol (IP) software stack to the UoSAT- 12 spacecraft, simple modifications to the SSTL ground station, and a series of tests to measure performance of various Internet applications. The spacecraft was reconfigured on orbit at very low cost. The total period between concept and the first tests was only 3 months. The tests included basic network connectivity (PING), automated clock synchronization (NTP), and reliable file transfers (FTP). Future tests are planned to include additional protocols such as Mobile IP, e-mail, and virtual private networks (VPN) to enable automated, operational spacecraft communication networks. The work performed and results of the initial phase of tests are summarized in this paper. This work is funded and directed by NASA/GSFC with technical leadership by CSC in arrangement with SSTL, and Vytek Wireless.

  6. Star Messenger: Galileo at the Millennium

    Science.gov (United States)

    White, R. E.

    1999-05-01

    Smith College has recently established the Louise B. and Edmund J. Kahn Liberal Arts Institute to foster interdisciplinary scholarship among the faculty. In the 1999-2000 academic year, the Kahn Institute is sponsoring a project entitled "Star Messenger: Galileo at the Millennium." The project will explore the impact of the astronomical discoveries of Galileo and his contemporaries on the Renaissance world-view and also use Galileo's experience as a lens for examining scientific and cultural developments at the symbolic juncture represented by the year 2000. Seven faculty fellows and 10-12 student fellows will participate in a year-long colloquium pursuing these themes, aided by the participation of some five Visiting Fellows. The inaugural public event will be a symposium on the historical Galileo, with presentation by three noted scholars, each of whom will return to campus for a second meeting with the Kahn colloquium. Additional events will include an exhibit of prints, artifacts, and rare books related to Galileo and his time, an early music concert featuring music composed by Galileo's father, and a series of other events sponsored by diverse departments and programs, all related to the broad themes of the Galileo project. The culminating events will be the premiere of a new music theater work, which will encapsulate the insights of the colloquium about human reactions to novel insights about the world, and a symposium presenting the research results of faculty and student fellows. The symposium will feature a capstone lecture by an visionary scholar projecting the implication of historical and contemporary trends into the future.

  7. The MESSENGER mission to Mercury: new insights into geological processes and evolution

    Science.gov (United States)

    Head, James W., III; Solomon, Sean C.; McNutt, Ralph L., Jr.; Blewett, David T.; Chapman, Clark R.; Domingue, Deborah L.; Evans, Larry G.; Gillis-Davis, Jeffrey J.; Hawkins, S. Edward, III; Helbert, Jörn; Holsclaw, Gregory M.; Izenberg, Noam R.; McClintock, William E.; McCoy, Timothy J.; Merline, William J.; Murchie, Scott L.; Nittler, Larrz R.; Phillips, Roger J.; Prockter, Louise M.; Robinson, Mark S.; Sprague, Ann L.; Strom, Robert G.; Vilas, Faith; Watters, Thomas R.; Zuber, Maria T.

    2008-09-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, a part of NASA's Discovery Program, was designed to answer six questions [1]: (1) What planetary formational processes led to Mercury's high ratio of metal to silicate? (2) What is the geological history of Mercury? (3) What are the nature and origin of Mercury's magnetic field? (4) What are the structure and state of Mercury's core? (5) What are the radar-reflective materials at Mercury's poles? (6) What are the important volatile species and their sources and sinks near Mercury? MESSENGER is currently midway through a complex interplanetary cruise phase that involves three flybys of Mercury. The first of these, on 14 January 2008, provided important new information relating to several of the questions above [2-13]. Here we summarize observations made during the flyby that are most relevant to new insights about geological processes that have operated on Mercury and implications for the planet's history [3, 8-13]. The instruments that provided the most direct information on the geological history of Mercury during this first encounter were the Mercury Dual Imaging System (MDIS) [14], the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) [15], and the Mercury Laser Altimeter (MLA) [16]. Among the many specific questions remaining following the Mariner 10 mission to Mercury (1974- 1975) were (1) the level of mineralogical and compositional diversity of the crust, which appeared relatively bland in Mariner 10 data, (2) the nature of the rest of the huge Caloris impact basin seen only partially in Mariner 10 images, (3) the origin of the extensive plains observed on the surface (ponded impact ejecta or extrusive lava flows?), (4) the diversity and global distribution of tectonic features that have deformed the crust and their implications for strain as a function of time, and (5) the bombardment chronology and geological history of Mercury [1, 17-19]. The viewing

  8. Monitoring global messenger RNA changes in externally controlled microarray experiments

    Science.gov (United States)

    van de Peppel, Jeroen; Kemmeren, Patrick; van Bakel, Harm; Radonjic, Marijana; van Leenen, Dik; Holstege, Frank C.P.

    2003-01-01

    Expression profiling is a universal tool, with a range of applications that benefit from the accurate determination of differential gene expression. To allow normalization using endogenous transcript levels, current microarray analyses assume that relatively few transcripts vary, or that any changes that occur are balanced. When normalization using endogenous genes is carried out, changes in expression levels are calculated relative to the behaviour of most of the transcripts. This does not reflect absolute changes if global shifts in messenger RNA populations occur. Using external RNA controls, we have set up microarray experiments to monitor global changes. The levels of most mRNAs were found to change during yeast stationary phase and human heat shock when external controls were included. Even small global changes had a significant effect on the number of genes reported as being differentially expressed. This suggests that global mRNA changes occur more frequently than is assumed at present, and shows that monitoring such effects may be important for the accurate determination of changes in gene expression. PMID:12671682

  9. Spacecraft environments interactions: Protecting against the effects of spacecraft charging

    Science.gov (United States)

    Herr, J. L.; Mccollum, M. B.

    1994-01-01

    The effects of the natural space environments on spacecraft design, development, and operation are the topic of a series of NASA Reference Publications currently being developed by the Electromagnetics and Environments Branch, Systems Analysis and Integration Laboratory, Marshall Space Flight Center. This primer, second in the series, describes the interactions between a spacecraft and the natural space plasma. Under certain environmental/spacecraft conditions, these interactions result in the phenomenon known as spacecraft charging. It is the focus of this publication to describe the phenomenon of spacecraft charging and its possible adverse effects on spacecraft and to present the key elements of a Spacecraft Charging Effects Protection Plan.

  10. Introducing GV : The Spacecraft Geometry Visualizer

    Science.gov (United States)

    Throop, Henry B.; Stern, S. A.; Parker, J. W.; Gladstone, G. R.; Weaver, H. A.

    2009-12-01

    GV (Geometry Visualizer) is a web-based program for planning spacecraft observations. GV is the primary planning tool used by the New Horizons science team to plan the encounter with Pluto. GV creates accurate 3D images and movies showing the position of planets, satellites, and stars as seen from an observer on a spacecraft or other body. NAIF SPICE routines are used throughout for accurate calculations of all geometry. GV includes 3D geometry rendering of all planetary bodies, lon/lat grids, ground tracks, albedo maps, stellar magnitudes, types and positions from HD and Tycho-2 catalogs, and spacecraft FOVs. It generates still images, animations, and geometric data tables. GV is accessed through an easy-to-use and flexible web interface. The web-based interface allows for uniform use from any computer and assures that all users are accessing up-to-date versions of the code and kernel libraries. Compared with existing planning tools, GV is often simpler, faster, lower-cost, and more flexible. GV was developed at SwRI to support the New Horizons mission to Pluto. It has been subsequently expanded to support multiple other missions in flight or under development, including Cassini, Messenger, Rosetta, LRO, and Juno. The system can be used to plan Earth-based observations such as occultations to high precision, and was used by the public to help plan 'Kodak Moment' observations of the Pluto system from New Horizons. Potential users of GV may contact the author for more information. Development of GV has been funded by the New Horizons, Rosetta, and LRO missions.

  11. Internet Technology on Spacecraft

    Science.gov (United States)

    Rash, James; Parise, Ron; Hogie, Keith; Criscuolo, Ed; Langston, Jim; Powers, Edward I. (Technical Monitor)

    2000-01-01

    The Operating Missions as Nodes on the Internet (OMNI) project has shown that Internet technology works in space missions through a demonstration using the UoSAT-12 spacecraft. An Internet Protocol (IP) stack was installed on the orbiting UoSAT-12 spacecraft and tests were run to demonstrate Internet connectivity and measure performance. This also forms the basis for demonstrating subsequent scenarios. This approach provides capabilities heretofore either too expensive or simply not feasible such as reconfiguration on orbit. The OMNI project recognized the need to reduce the risk perceived by mission managers and did this with a multi-phase strategy. In the initial phase, the concepts were implemented in a prototype system that includes space similar components communicating over the TDRS (space network) and the terrestrial Internet. The demonstration system includes a simulated spacecraft with sample instruments. Over 25 demonstrations have been given to mission and project managers, National Aeronautics and Space Administration (NASA), Department of Defense (DoD), contractor technologists and other decisions makers, This initial phase reached a high point with an OMNI demonstration given from a booth at the Johnson Space Center (JSC) Inspection Day 99 exhibition. The proof to mission managers is provided during this second phase with year 2000 accomplishments: testing the use of Internet technologies onboard an actual spacecraft. This was done with a series of tests performed using the UoSAT-12 spacecraft. This spacecraft was reconfigured on orbit at very low cost. The total period between concept and the first tests was only 6 months! On board software was modified to add an IP stack to support basic IP communications. Also added was support for ping, traceroute and network timing protocol (NTP) tests. These tests show that basic Internet functionality can be used onboard spacecraft. The performance of data was measured to show no degradation from current

  12. Spacecraft Attitude Determination

    DEFF Research Database (Denmark)

    Bak, Thomas

    determination based on simple, reliable sensors. Meeting these objectives with a single vector magnetometer is difficult and requires temporal fusion of data in order to avoid local observability problems. In order to guaranteed globally nonsingular solutions, quaternions are generally the preferred attitude......This thesis describes the development of an attitude determination system for spacecraft based only on magnetic field measurements. The need for such system is motivated by the increased demands for inexpensive, lightweight solutions for small spacecraft. These spacecraft demands full attitude...... is a detailed study of the influence of approximations in the modeling of the system. The quantitative effects of errors in the process and noise statistics are discussed in detail. The third contribution is the introduction of these methods to the attitude determination on-board the Ørsted satellite...

  13. Revamping Spacecraft Operational Intelligence

    Science.gov (United States)

    Hwang, Victor

    2012-01-01

    The EPOXI flight mission has been testing a new commercial system, Splunk, which employs data mining techniques to organize and present spacecraft telemetry data in a high-level manner. By abstracting away data-source specific details, Splunk unifies arbitrary data formats into one uniform system. This not only reduces the time and effort for retrieving relevant data, but it also increases operational visibility by allowing a spacecraft team to correlate data across many different sources. Splunk's scalable architecture coupled with its graphing modules also provide a solid toolset for generating data visualizations and building real-time applications such as browser-based telemetry displays.

  14. How MESSENGER Meshes Simulations and Games with Citizen Science

    Science.gov (United States)

    Hirshon, B.; Chapman, C. R.; Edmonds, J.; Goldstein, J.; Hallau, K. G.; Solomon, S. C.; Vanhala, H.; Weir, H. M.; Messenger Education; Public Outreach (Epo) Team

    2010-12-01

    How MESSENGER Meshes Simulations and Games with Citizen Science In the film The Last Starfighter, an alien civilization grooms their future champion—a kid on Earth—using a video game. As he gains proficiency in the game, he masters the skills he needs to pilot a starship and save their civilization. The NASA MESSENGER Education and Public Outreach (EPO) Team is using the same tactic to train citizen scientists to help the Science Team explore the planet Mercury. We are building a new series of games that appear to be designed primarily for fun, but that guide players through a knowledge and skill set that they will need for future science missions in support of MESSENGER mission scientists. As players score points, they gain expertise. Once they achieve a sufficiently high score, they will be invited to become participants in Mercury Zoo, a new program being designed by Zooniverse. Zooniverse created Galaxy Zoo and Moon Zoo, programs that allow interested citizens to participate in the exploration and interpretation of galaxy and lunar data. Scientists use the citizen interpretations to further refine their exploration of the same data, thereby narrowing their focus and saving precious time. Mercury Zoo will be designed with input from the MESSENGER Science Team. This project will not only support the MESSENGER mission, but it will also add to the growing cadre of informed members of the public available to help with other citizen science projects—building on the concept that engaged, informed citizens can help scientists make new discoveries. The MESSENGER EPO Team comprises individuals from the American Association for the Advancement of Science (AAAS); Carnegie Academy for Science Education (CASE); Center for Educational Resources (CERES) at Montana State University (MSU) - Bozeman; National Center for Earth and Space Science Education (NCESSE); Johns Hopkins University Applied Physics Laboratory (JHU/APL); National Air and Space Museum (NASM); Science

  15. Cluster PEACE observations of electrons of spacecraft origin

    Directory of Open Access Journals (Sweden)

    S. Szita

    Full Text Available The two PEACE (Plasma Electron And Current Experiment sensors on board each Cluster spacecraft sample the electron velocity distribution across the full 4 solid angle and the energy range 0.7 eV to 26 keV with a time resolution of 4 s. We present high energy and angular resolution 3D observations of electrons of spacecraft origin in the various environments encountered by the Cluster constellation, including a lunar eclipse interval where the spacecraft potential was reduced but remained positive, and periods of ASPOC (Active Spacecraft POtential Control operation which reduced the spacecraft potential. We demonstrate how the spacecraft potential may be found from a gradient change in the PEACE low energy spectrum, and show how the observed spacecraft electrons are confined by the spacecraft potential. We identify an intense component of the spacecraft electrons with energies equivalent to the spacecraft potential, the arrival direction of which is seen to change when ASPOC is switched on. Another spacecraft electron component, observed in the sunward direction, is reduced in the eclipse but unaffected by ASPOC, and we believe this component is produced in the analyser by solar UV. We find that PEACE anodes with a look direction along the spacecraft surfaces are more susceptible to spacecraft electron contamination than those which look perpendicular to the surface, which justifies the decision to mount PEACE with its field-of-view radially outward rather than tangentially.

    Key words. Magnetosheric physics (general or miscellaneous Space plasma physics (spacecraft sheaths, wakes, charging

  16. Cluster PEACE observations of electrons of spacecraft origin

    Directory of Open Access Journals (Sweden)

    S. Szita

    2001-09-01

    Full Text Available The two PEACE (Plasma Electron And Current Experiment sensors on board each Cluster spacecraft sample the electron velocity distribution across the full 4 solid angle and the energy range 0.7 eV to 26 keV with a time resolution of 4 s. We present high energy and angular resolution 3D observations of electrons of spacecraft origin in the various environments encountered by the Cluster constellation, including a lunar eclipse interval where the spacecraft potential was reduced but remained positive, and periods of ASPOC (Active Spacecraft POtential Control operation which reduced the spacecraft potential. We demonstrate how the spacecraft potential may be found from a gradient change in the PEACE low energy spectrum, and show how the observed spacecraft electrons are confined by the spacecraft potential. We identify an intense component of the spacecraft electrons with energies equivalent to the spacecraft potential, the arrival direction of which is seen to change when ASPOC is switched on. Another spacecraft electron component, observed in the sunward direction, is reduced in the eclipse but unaffected by ASPOC, and we believe this component is produced in the analyser by solar UV. We find that PEACE anodes with a look direction along the spacecraft surfaces are more susceptible to spacecraft electron contamination than those which look perpendicular to the surface, which justifies the decision to mount PEACE with its field-of-view radially outward rather than tangentially.Key words. Magnetosheric physics (general or miscellaneous Space plasma physics (spacecraft sheaths, wakes, charging

  17. Decreased neuronal nitric oxide synthase messenger RNA and somatostatin messenger RNA in the striatum of Huntington's disease.

    Science.gov (United States)

    Norris, P J; Waldvogel, H J; Faull, R L; Love, D R; Emson, P C

    1996-06-01

    The cellular abundance of neuronal nitric oxide synthase and somatostatin messenger RNAs was compared in the caudate nucleus, putamen and sensorimotor cortex of Huntington's disease and control cases. Neuronal nitric oxide synthase messenger RNA was significantly decreased in the caudate nucleus and putamen, but not in the sensorimotor cortex in Huntington's disease; the decrease in neuronal nitric oxide synthase messenger RNA became more pronounced with the severity of the disease. Somatostatin gene expression was significantly decreased in the dorsal putamen in Huntington's disease, but was essentially unchanged in all other regions examined. The density of neurons expressing detectable levels of neuronal nitric oxide synthase messenger RNA was reduced in the striata of Huntington's disease cases with advanced pathology; the density of neurons expressing detectable levels of somatostatin messenger RNA was similar in control and Huntington's disease cases. Neuropeptide Y-, somatostatin- and NADPH-diaphorase-positive neurons were consistently present throughout the striatum across all the grades of the disease. Neuronal nitric oxide synthase and NADPH-diaphorase activity (a histochemical marker for nitric oxide synthase-containing neurons) co-localize with somatostatin and neuropeptide Y in interneurons in the human striatum and cerebral cortex. Although the neurodegeneration associated with Huntington's disease is most evident in the striatum (particularly the dorsal regions), neuronal nitric oxide synthase/neuropeptide Y/somatostatin interneurons are relatively spared. Nitric oxide released by neuronal nitric oxide synthase-containing neurons may mediate glutamate-induced excitotoxic cell death, a mechanism proposed to be instrumental in causing the neurodegeneration seen in Huntington's disease. The results described here suggest that although the population of interneurons containing somatostatin, neuropeptide Y and neuronal nitric oxide synthase do survive in

  18. Spacecraft crew escape

    Science.gov (United States)

    Miller, B. A.

    Safe crew escape from spacecraft is extremely difficult to engineer and has large cost and vehicle payload penalties. Because of these factors calculated risks have apparently been taken and only the most rudimentary means of crew protecion have been provided for space programs. Although designed for maximum reliability and safety a calculated risk is taken that on-balance it is more acceptable to risk the loss of possibly some or all occupants than introduce the mass, cost and complexity of an escape system. This philosophy was accepted until the Challenger tragedy. It is now clear that the use of this previously acceptable logic is invalid and that provisions must be made for spacecraft crew escape in the event of a catastrophic accident. This paper reviews the funded studies and subsequent proposals undertaken by Martin-Baker for the use of both encapsullated and open ejection seats for the Hermes Spaceplane. The technical difficulties, special innovations and future applications are also discussed.

  19. Spacecraft Collision Avoidance

    Science.gov (United States)

    Bussy-Virat, Charles

    The rapid increase of the number of objects in orbit around the Earth poses a serious threat to operational spacecraft and astronauts. In order to effectively avoid collisions, mission operators need to assess the risk of collision between the satellite and any other object whose orbit is likely to approach its trajectory. Several algorithms predict the probability of collision but have limitations that impair the accuracy of the prediction. An important limitation is that uncertainties in the atmospheric density are usually not taken into account in the propagation of the covariance matrix from current epoch to closest approach time. The Spacecraft Orbital Characterization Kit (SpOCK) was developed to accurately predict the positions and velocities of spacecraft. The central capability of SpOCK is a high accuracy numerical propagator of spacecraft orbits and computations of ancillary parameters. The numerical integration uses a comprehensive modeling of the dynamics of spacecraft in orbit that includes all the perturbing forces that a spacecraft is subject to in orbit. In particular, the atmospheric density is modeled by thermospheric models to allow for an accurate representation of the atmospheric drag. SpOCK predicts the probability of collision between two orbiting objects taking into account the uncertainties in the atmospheric density. Monte Carlo procedures are used to perturb the initial position and velocity of the primary and secondary spacecraft from their covariance matrices. Developed in C, SpOCK supports parallelism to quickly assess the risk of collision so it can be used operationally in real time. The upper atmosphere of the Earth is strongly driven by the solar activity. In particular, abrupt transitions from slow to fast solar wind cause important disturbances of the atmospheric density, hence of the drag acceleration that spacecraft are subject to. The Probability Distribution Function (PDF) model was developed to predict the solar wind speed

  20. Very Small Interstellar Spacecraft

    Science.gov (United States)

    Peck, Mason A.

    2007-02-01

    This paper considers lower limits of length scale in spacecraft: interstellar vehicles consisting of little more material than found in a typical integrated-circuit chip. Some fundamental scaling principles are introduced to show how the dynamics of the very small can be used to realize interstellar travel with minimal advancements in technology. Our recent study for the NASA Institute for Advanced Concepts provides an example: the use of the Lorentz force that acts on electrically charged spacecraft traveling through planetary and stellar magnetospheres. Schaffer and Burns, among others, have used Cassini and Voyager imagery to show that this interaction is responsible for some of the resonances in the orbital dynamics of dust in Jupiter's and Saturn's rings. The Lorentz force turns out to vary in inverse proportion to the square of this characteristic length scale, making it a more effective means of propelling tiny spacecraft than solar sailing. Performance estimates, some insight into plasma interactions, and some hardware concepts are offered. The mission architectures considered here involve the use of these propellantless propulsion techniques for acceleration within our solar system and deceleration near the destination. Performance estimates, some insight into plasma interactions, and some hardware concepts are offered. The mission architectures considered here involve the use of these propellantless propulsion techniques for acceleration within our solar system and deceleration near the destination. We might envision a large number of such satellites with intermittent, bursty communications set up as a one-dimensional network to relay signals across great distances using only the power likely from such small spacecraft. Conveying imagery in this fashion may require a long time because of limited power, but the prospect of imaging another star system close-up ought to be worth the wait.

  1. POEMMA: Probe Of Extreme Multi-Messenger Astrophysics

    DEFF Research Database (Denmark)

    Olinto, A. V.; Adams, J. H.; Aloisio, R.

    2017-01-01

    The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) mission is being designed to establish charged-particle astronomy with ultra-high energy cosmic rays (UHECRs) and to observe cosmogenic tau neutrinos (CTNs). The study of UHECRs and CTNs from space will yield orders-of-magnitude increase...

  2. Circuit Formation by Spatio-Temporal Control of Messenger RNA ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Circuit Formation by Spatio-Temporal Control of Messenger RNA Translation. The connections inside the brain need to be wired in a precise manner during development to ensure its proper function. This project will provide insight into circuit formation to help us understand how axon regeneration can improve clinical ...

  3. Making Sense of 2.5 Million Surface Reflectance Spectra of Mercury from MESSENGER

    Science.gov (United States)

    D'Amore, M.; Helbert, J.; D'Incecco, P.; Domingue, D. L.; Izenberg, N. R.; McClintock, W. E.

    2012-12-01

    The Mercury Atmospheric and Surface and Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has mapped the surface of Mercury on a global basis during its one-year primary orbital mission and the first third of its extended mission, producing ~2.5 million spectra from March 2011 to July 2012. The primary challenge to analyzing this dataset is to cope with its large size. In earlier studies of MASCS data, we combined several approaches, ranging from principal component analysis (PCA) to unsupervised cluster analysis and regridding to global and local fixed grids. Each of those techniques provided insight into spectral variations for different volumes of data, but each was quickly overcome by the growing dataset. The most recent version of our data analysis procedure uses PostgreSQL, a type of database management that controls the creation, integrity, maintenance, and use of a database. It embeds a high-level query language, which greatly simplifies database organization as well as retrieval and presentation of database information. We set up a data pipeline to update automatically the MASCS data, read them from the NASA Planetary Data System format, regrid the data to a common grid length, and store all information in the database. All data are then readily available to any authorized user in our network. We are working on a library to access the data directly from within our analysis software, and some preliminary functions have been implemented. As an example, the calculation of a parameter representing the database takes 2 s even for the full dataset of 2.5 million entries. It is thus straightforward to create and analyze rapidly the data, as for example the distribution of normalized radiance at a fixed wavelength. The new methodology provides facilities for controlling data access, enforcing data integrity, managing concurrency control, and recovering the database after a failure and

  4. REQUIREMENTS FOR IMAGE QUALITY OF EMERGENCY SPACECRAFTS

    Directory of Open Access Journals (Sweden)

    A. I. Altukhov

    2015-05-01

    Full Text Available The paper deals with the method for formation of quality requirements to the images of emergency spacecrafts. The images are obtained by means of remote sensing of near-earth space orbital deployment in the visible range. of electromagnetic radiation. The method is based on a joint taking into account conditions of space survey, characteristics of surveillance equipment, main design features of the observed spacecrafts and orbital inspection tasks. Method. Quality score is the predicted linear resolution image that gives the possibility to create a complete view of pictorial properties of the space image obtained by electro-optical system from the observing satellite. Formulation of requirements to the numerical value of this indicator is proposed to perform based on the properties of remote sensing system, forming images in the conditions of outer space, and the properties of the observed emergency spacecraft: dimensions, platform construction of the satellite, on-board equipment placement. For method implementation the authors have developed a predictive model of requirements to a linear resolution for images of emergency spacecrafts, making it possible to select the intervals of space shooting and get the satellite images required for quality interpretation. Main results. To verify the proposed model functionality we have carried out calculations of the numerical values for the linear resolution of the image, ensuring the successful task of determining the gross structural damage of the spacecrafts and identifying changes in their spatial orientation. As input data were used with dimensions and geometric primitives corresponding to the shape of deemed inspected spacecrafts: Resurs-P", "Canopus-B", "Electro-L". Numerical values of the linear resolution images have been obtained, ensuring the successful task solution for determining the gross structural damage of spacecrafts.

  5. Spacecraft Modularity for Serviceable Satellites

    Science.gov (United States)

    Reed, Benjamin B.; Rossetti, Dino; Keer, Beth; Panek, John; Cepollina, Frank; Ritter, Robert

    2015-01-01

    Spacecraft modularity has been a topic of interest at NASA since the 1970s, when the Multi-Mission Modular Spacecraft (MMS) was developed at the Goddard Space Flight Center. Since then, modular concepts have been employed for a variety of spacecraft and, as in the case of the Hubble Space Telescope (HST) and the International Space Station (ISS), have been critical to the success of on-orbit servicing. Modularity is even more important for future robotic servicing. Robotic satellite servicing technologies under development by NASA can extend mission life and reduce life-cycle cost and risk. These are optimized when the target spacecraft is designed for servicing, including advanced modularity. This paper will explore how spacecraft design, as demonstrated by the Reconfigurable Operational spacecraft for Science and Exploration (ROSE) spacecraft architecture, and servicing technologies can be developed in parallel to fully take advantage of the promise of both.

  6. Seasonal Variations of Mercury's Magnesium Dayside Exosphere from MESSENGER Observations

    Science.gov (United States)

    Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

    2017-01-01

    The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, approx.17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of approx. 6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5/cu cm to 50/cu cm and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1×10(exp 5)/sq cm/s to 8×10(exp 5)/sq cm/s.

  7. Light third-generation squarks from flavour gauge messengers

    CERN Document Server

    Brümmer, Felix; Weiler, Andreas

    2014-01-01

    We study models of gauge-mediated supersymmetry breaking with a gauged horizontal SU(3)_F symmetry acting on the quark superfields. If SU(3)_F is broken non-supersymmetrically by F-term vacuum expectation values, the massive gauge bosons and gauginos become messengers for SUSY breaking mediation. These gauge messenger fields induce a flavour-dependent, negative contribution to the soft masses of the squarks at one loop. In combination with the soft terms from standard gauge mediation, one obtains large and degenerate first- and second-generation squark masses, while the stops and sbottoms are light. We discuss the implications of this mechanism for the superparticle spectrum and for flavour precision observables. We also provide an explicit realization in a model with simultaneous SUSY and SU(3)_F breaking.

  8. Nonrepetitive DNA Sequence Representation in Sea Urchin Embryo Messenger RNA

    Science.gov (United States)

    Goldberg, Robert B.; Galau, Glenn A.; Britten, Roy J.; Davidson, Eric H.

    1973-01-01

    Messenger RNA was prepared from developing sea urchin gastrulae by puromycin release from polyribosomes. Approximately 60% of the total mRNA radioactivity of the postnuclear supernatant was recovered and shown to be free of any other labeled RNA species such as ribosomal and nuclear RNA. The mRNA was examined by hybridization to DNA present in great excess. The mRNA hybridizes almost exclusively with nonrepetitive DNA. Almost all of the messenger RNA molecules of sea urchin gastrulae therefore consist of transcripts from nonrepetitive sequences. It appears that the structural genes expressed at this stage are typically not repeated in the genome and the mRNA does not include recognizable repetitive sequence. PMID:4519642

  9. The models evaluating courier and messenger companies in Poland

    Directory of Open Access Journals (Sweden)

    Chodakowska Ewa

    2016-12-01

    Full Text Available Data Envelopment Analysis (DEA is a well-established, popular, and often used method for efficiency evaluation of units from all sector, both commercial and non-profit organisations, of any scale of operations. Network DEA models are a relatively recent approach used to examine the efficiency of decision-making units (DMUs having an internal structure of sub-processes. The article presents the concept of DEA network models in estimating the efficiency of courier and messenger companies with relations to their business clients. The considerations are supported by an example of data concerning leaders from the sector of couriers and messengers in Poland and one of the biggest and most popular online stores. The results are compared with the traditional DEA approach. In addition, to measure reliability for DEA scores, the jackknife procedure was performed. The author proves the usefulness of network DEA as a research and management tool.

  10. Mercury's exosphere: observations during MESSENGER's First Mercury flyby.

    Science.gov (United States)

    McClintock, William E; Bradley, E Todd; Vervack, Ronald J; Killen, Rosemary M; Sprague, Ann L; Izenberg, Noam R; Solomon, Sean C

    2008-07-04

    During MESSENGER's first Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer measured Mercury's exospheric emissions, including those from the antisunward sodium tail, calcium and sodium close to the planet, and hydrogen at high altitudes on the dayside. Spatial variations indicate that multiple source and loss processes generate and maintain the exosphere. Energetic processes connected to the solar wind and magnetospheric interaction with the planet likely played an important role in determining the distributions of exospheric species during the flyby.

  11. Faraday rotation fluctuations of MESSENGER radio signals through the equatorial lower corona near solar minimum

    Science.gov (United States)

    Wexler, D. B.; Jensen, E. A.; Hollweg, J. V.; Heiles, C.; Efimov, A. I.; Vierinen, J.; Coster, A. J.

    2017-02-01

    Faraday rotation (FR) of transcoronal radio transmissions from spacecraft near superior conjunction enables study of the temporal variations in coronal plasma density, velocity, and magnetic field. The MESSENGER spacecraft 8.4 GHz radio, transmitting through the corona with closest line-of-sight approach 1.63-1.89 solar radii and near-equatorial heliolatitudes, was recorded soon after the deep solar minimum of solar cycle 23. During egress from superior conjunction, FR gradually decreased, and an overlay of wave-like FR fluctuations (FRFs) with periods of hundreds to thousands of seconds was found. The FRF power spectrum was characterized by a power law relation, with the baseline spectral index being -2.64. A transient power increase showed relative flattening of the spectrum and bands of enhanced spectral power at 3.3 mHz and 6.1 mHz. Our results confirm the presence of coronal FRF similar to those described previously at greater solar offset. Interpreted as Alfvén waves crossing the line of sight radially near the proximate point, low-frequency FRF convey an energy flux density higher than that of the background solar wind kinetic energy, but only a fraction of that required to accelerate the solar wind. Even so, this fraction is quite variable and potentially escalates to energetically significant values with relatively modest changes in estimated magnetic field strength and electron concentration. Given the uncertainties in these key parameters, as well as in solar wind properties close to the Sun at low heliolatitudes, we cannot yet confidently assign the quantitative role for Alfvén wave energy from this region in driving the slow solar wind.

  12. High Throughput Hall Thruster for Small Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek is developing a high throughput nominal 100-W Hall Effect Thruster. This device is well sized for spacecraft ranging in size from several tens of kilograms to...

  13. A Self-Regulating Freezable Heat Exchanger for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A spacecraft thermal control system must keep the vehicle, avionics and atmosphere (if crewed) within a defined temperature range. Since water is non-toxic and good...

  14. A Self-Regulating Freezable Heat Exchanger for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A spacecraft thermal control system must keep the cabin (both air and its structure if manned) and electronic equipment within a narrow temperature range even though...

  15. Spacecraft rendezvous and docking

    DEFF Research Database (Denmark)

    Jørgensen, John Leif

    1999-01-01

    The phenomenons and problems encountered when a rendezvous manoeuvre, and possible docking, of two spacecrafts has to be performed, have been the topic for numerous studies, and, details of a variety of scenarios has been analysed. So far, all solutions that has been brought into realization has...... been based entirely on direct human supervision and control. This paper describes a vision-based system and methodology, that autonomously generates accurate guidance information that may assist a human operator in performing the tasks associated with both the rendezvous and docking navigation...... relative pose information to assist the human operator during the docking phase. The closed loop and operator assistance performance of the system have been assessed using a test bench including human operator, navigation module and high fidelity visualization module. The tests performed verified...

  16. Human Spacecraft Structures Internship

    Science.gov (United States)

    Bhakta, Kush

    2017-01-01

    DSG will be placed in halo orbit around themoon- Platform for international/commercialpartners to explore lunar surface- Testbed for technologies needed toexplore Mars• Habitat module used to house up to 4crew members aboard the DSG- Launched on EM-3- Placed inside SLS fairing Habitat Module - Task Habitat Finite Element Model Re-modeled entire structure in NX2) Used Beam and Shell elements torepresent the pressure vessel structure3) Created a point cloud of centers of massfor mass components- Can now inspect local moments andinertias for thrust ring application8/ Habitat Structure – Docking Analysis Problem: Artificial Gravity may be necessary forastronaut health in deep spaceGoal: develop concepts that show how artificialgravity might be incorporated into a spacecraft inthe near term Orion Window Radiant Heat Testing.

  17. Operationally Responsive Spacecraft Subsystem Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Saber Astronautics proposes spacecraft subsystem control software which can autonomously reconfigure avionics for best performance during various mission conditions....

  18. Spacecraft telecommunications system mass estimates

    Science.gov (United States)

    Yuen, J. H.; Sakamoto, L. L.

    1988-01-01

    Mass is the most important limiting parameter for present-day planetary spacecraft design, In fact, the entire design can be characterized by mass. The more efficient the design of the spacecraft, the less mass will be required. The communications system is an essential and integral part of planetary spacecraft. A study is presented of the mass attributable to the communications system for spacecraft designs used in recent missions in an attempt to help guide future design considerations and research and development efforts. The basic approach is to examine the spacecraft by subsystem and allocate a portion of each subsystem to telecommunications. Conceptually, this is to divide the spacecraft into two parts, telecommunications and nontelecommunications. In this way, it is clear what the mass attributable to the communications system is. The percentage of mass is calculated using the actual masses of the spacecraft parts, except in the case of CRAF. In that case, estimated masses are used since the spacecraft was not yet built. The results show that the portion of the spacecraft attributable to telecommunications is substantial. The mass fraction for Voyager, Galileo, and CRAF (Mariner Mark 2) is 34, 19, and 18 percent, respectively. The large reduction of telecommunications mass from Voyager to Galileo is mainly due to the use of a deployable antenna instead of the solid antenna on Voyager.

  19. Common observations of solar X-rays from SPHINX/CORONAS-PHOTON and XRS/MESSENGER

    Science.gov (United States)

    Kepa, Anna; Sylwester, Janusz; Sylwester, Barbara; Siarkowski, Marek; Mrozek, Tomasz; Gryciuk, Magdalena; Phillips, Kenneth

    SphinX was a soft X-ray spectrophotometer constructed in the Space Research Centre of Polish Academy of Sciences. The instrument was launched on 30 January 2009 aboard CORONAS-PHOTON satellite as a part of TESIS instrument package. SphinX measured total solar X-ray flux in the energy range from 1 to 15 keV during the period of very low solar activity from 20 February to 29 November 2009. For these times the solar detector (X-ray Spectrometer - XRS) onboard MESSENGER also observed the solar X-rays from a different vantage point. XRS measured the radiation in similar energy range. We present results of the comparison of observations from both instruments and show the preliminary results of physical analysis of spectra for selected flares.

  20. MESSENGER and Venus Express Observations of the Near-tail of Venus: Magnetic Flux Transport, Current Sheet Structure, and Flux Rope Formation

    Science.gov (United States)

    Slavin, James A.; Boardsen, S. A.; Sarantos, M.; Acuna, M. H.; Anderson, B. J.; Barabash, S.; Benna, M.; Fraenz, M.; Gloeckler, G.; Gold, R. E.; hide

    2008-01-01

    At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 km) during its second flyby of Venus en route to its 2011 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER'S first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example to date of a solar wind - ionosphere planetary interaction. We present MESSENGER observations of the near-tail of Venus with emphasis on determining the time scales for magnetic flux transport, the structure of the cross-tail current sheet at very low altitudes (approx. 300 to 1000 km), and the nature and origin of a magnetic flux rope observed in the current sheet. The availability of the simultaneous Venus Express upstream measurements provides a unique opportunity to examine the influence of solar wind plasma and interplanetary magnetic field conditions on this planet's solar wind interaction at solar minimum.

  1. Analyzing Spacecraft Telecommunication Systems

    Science.gov (United States)

    Kordon, Mark; Hanks, David; Gladden, Roy; Wood, Eric

    2004-01-01

    Multi-Mission Telecom Analysis Tool (MMTAT) is a C-language computer program for analyzing proposed spacecraft telecommunication systems. MMTAT utilizes parameterized input and computational models that can be run on standard desktop computers to perform fast and accurate analyses of telecommunication links. MMTAT is easy to use and can easily be integrated with other software applications and run as part of almost any computational simulation. It is distributed as either a stand-alone application program with a graphical user interface or a linkable library with a well-defined set of application programming interface (API) calls. As a stand-alone program, MMTAT provides both textual and graphical output. The graphs make it possible to understand, quickly and easily, how telecommunication performance varies with variations in input parameters. A delimited text file that can be read by any spreadsheet program is generated at the end of each run. The API in the linkable-library form of MMTAT enables the user to control simulation software and to change parameters during a simulation run. Results can be retrieved either at the end of a run or by use of a function call at any time step.

  2. Printed Spacecraft Separation System

    Energy Technology Data Exchange (ETDEWEB)

    Dehoff, Ryan R [ORNL; Holmans, Walter [Planetary Systems Corporation

    2016-10-01

    In this project Planetary Systems Corporation proposed utilizing additive manufacturing (3D printing) to manufacture a titanium spacecraft separation system for commercial and US government customers to realize a 90% reduction in the cost and energy. These savings were demonstrated via “printing-in” many of the parts and sub-assemblies into one part, thus greatly reducing the labor associated with design, procurement, assembly and calibration of mechanisms. Planetary Systems Corporation redesigned several of the components of the separation system based on additive manufacturing principles including geometric flexibility and the ability to fabricate complex designs, ability to combine multiple parts of an assembly into a single component, and the ability to optimize design for specific mechanical property targets. Shock absorption was specifically targeted and requirements were established to attenuate damage to the Lightband system from shock of initiation. Planetary Systems Corporation redesigned components based on these requirements and sent the designs to Oak Ridge National Laboratory to be printed. ORNL printed the parts using the Arcam electron beam melting technology based on the desire for the parts to be fabricated from Ti-6Al-4V based on the weight and mechanical performance of the material. A second set of components was fabricated from stainless steel material on the Renishaw laser powder bed technology due to the improved geometric accuracy, surface finish, and wear resistance of the material. Planetary Systems Corporation evaluated these components and determined that 3D printing is potentially a viable method for achieving significant cost and savings metrics.

  3. Spacecraft thermal modelling

    Science.gov (United States)

    Chin, J. H.; Panczak, T. D.; Fried, L.

    1992-09-01

    Thermal modeling of spacecraft requires approaches which can handle dominant radiative heat transfers and many special thermal control components. Present network-type thermal analyzers allow simulation, especially for components with rectangular geometries, but at the expense of considerable awkwardness and much error-prone manual input. The user interfaces for pre- and postprocessing for these analyzers are also very deficient. Finite element thermal analyzers solve some of the analytical difficulties, but are not widely used because they lack the flexibility to simulate special operations. The Galerkin finite element method (GFEM) distributes the contributions within an element to the element nodal points. The assembly of the contributions from all elements yields a system of energy balance equations for the nodal points of the system. Monte Carlo raytracing, in conjunction with a GFEM energy distribution to element nodal points, yields a procedure of consistent nonisothermal surface radiation exchange. This procedure reduces a source of simulation error caused by nonuniform element illumination and shading. Orbital heating, fluid flow and special analysis features are discussed. The main analysis program is interfaced to the preprocessing and postprocessing modules.

  4. Mercury's complex exosphere: results from MESSENGER's third flyby.

    Science.gov (United States)

    Vervack, Ronald J; McClintock, William E; Killen, Rosemary M; Sprague, Ann L; Anderson, Brian J; Burger, Matthew H; Bradley, E Todd; Mouawad, Nelly; Solomon, Sean C; Izenberg, Noam R

    2010-08-06

    During MESSENGER's third flyby of Mercury, the Mercury Atmospheric and Surface Composition Spectrometer detected emission from ionized calcium concentrated 1 to 2 Mercury radii tailward of the planet. This measurement provides evidence for tailward magnetospheric convection of photoions produced inside the magnetosphere. Observations of neutral sodium, calcium, and magnesium above the planet's north and south poles reveal altitude distributions that are distinct for each species. A two-component sodium distribution and markedly different magnesium distributions above the two poles are direct indications that multiple processes control the distribution of even single species in Mercury's exosphere.

  5. Was my message read?: Privacy and Signaling on Facebook Messenger

    OpenAIRE

    Hoyle, Roberto; Das, Srijita; Kapadia, Apu; Lee, Adam J.; Vaniea, Kami

    2017-01-01

    Major online messaging services such as Facebook Messenger and WhatsApp are starting to provide users with real-time information about when people read their messages. While useful, this feature has the potential to negatively impact privacy as well as cause concern over access to self. We report on two surveys using Mechanical Turk which looked at senders' (N=402) use of and reactions to the `message seen' feature, and recipients' (N=316) privacy and signaling behaviors in the face of such v...

  6. Lunar shadow eclipse prediction models for the Earth orbiting spacecraft: Comparison and application to LEO and GEO spacecrafts

    Science.gov (United States)

    Srivastava, Vineet K.; Kumar, Jai; Kulshrestha, Shivali; Srivastava, Ashutosh; Bhaskar, M. K.; Kushvah, Badam Singh; Shiggavi, Prakash; Vallado, David A.

    2015-05-01

    A solar eclipse occurs when the Sun, Moon and Earth are aligned in such a way that shadow of the Moon falls on the Earth. The Moon's shadow also falls on the Earth orbiting spacecraft. In this case, the alignment of the Sun, Moon, and spacecraft is similar to that of the Sun, Moon, and Earth but this phenomenon is often referred as a lunar eclipse falling on the spacecraft. Lunar eclipse is not as regular in terms of times of occurrence, duration, and depth as the Earth shadow eclipse and number of its occurrence per orbital location per year ranges from zero to four with an average of two per year; a spacecraft may experience two to three lunar eclipses within a twenty-four hour period [2]. These lunar eclipses can cause severe spacecraft operational problems. This paper describes two lunar shadow eclipse prediction models using a projection map approach and a line of intersection method by extending the Earth shadow eclipse models described by Srivastava et al. [10,11] for the Earth orbiting spacecraft. The attractive feature of both models is that they are much easier to implement. Both mathematical models have been simulated for two Indian low Earth orbiting spacecrafts: Oceansat-2, Saral-1, and two geostationary spacecrafts: GSAT-10, INSAT-4CR. Results obtained by the models compare well with lunar shadow model given by Escobal and Robertson [12], and high fidelity commercial software package, Systems Tool Kit (STK) of AGI.

  7. MESSENGER E/V/H/SW EPPS CALIBRATED FIPS DDR V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Energetic Particle and Plasma Spectrometer (EPPS) calibrated observations, also known as DDRs. The system...

  8. MESSENGER E/V/H/SW EPPS CALIBRATED EPS CDR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Energetic Particle and Plasma Spectrometer (EPPS) calibrated observations, also known as CDRs. The system...

  9. MESSENGER E/V/H/SW EPPS CALIBRATED FIPS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Energetic Particle and Plasma Spectrometer (EPPS) calibrated observations, also known as CDRs. The system...

  10. MESSENGER E/V/H/SW EPPS CALIBRATED FIPS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Energetic Particle and Plasma Spectrometer (EPPS) calibrated observations, also known as DDRs. The system...

  11. MESSENGER E/V/H MERCURY LASER ALTIMETER 2 EDR RAW DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Mercury Laser Altimeter (MLA) uncalibrated observations, also known as Experiment Data Records, or EDRs....

  12. MESSENGER E/V/H GRNS 3 NEUTRON SPECTROMETER CDR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Neutron Spectrometer (NS) calibrated data records (CDRs). The NS experiment is a neutron spectrometer...

  13. Intelligent spacecraft module

    Science.gov (United States)

    Oungrinis, Konstantinos-Alketas; Liapi, Marianthi; Kelesidi, Anna; Gargalis, Leonidas; Telo, Marinela; Ntzoufras, Sotiris; Paschidi, Mariana

    2014-12-01

    The paper presents the development of an on-going research project that focuses on a human-centered design approach to habitable spacecraft modules. It focuses on the technical requirements and proposes approaches on how to achieve a spatial arrangement of the interior that addresses sufficiently the functional, physiological and psychosocial needs of the people living and working in such confined spaces that entail long-term environmental threats to human health and performance. Since the research perspective examines the issue from a qualitative point of view, it is based on establishing specific relationships between the built environment and its users, targeting people's bodily and psychological comfort as a measure toward a successful mission. This research has two basic branches, one examining the context of the system's operation and behavior and the other in the direction of identifying, experimenting and formulating the environment that successfully performs according to the desired context. The latter aspect is researched upon the construction of a scaled-model on which we run series of tests to identify the materiality, the geometry and the electronic infrastructure required. Guided by the principles of sensponsive architecture, the ISM research project explores the application of the necessary spatial arrangement and behavior for a user-centered, functional interior where the appropriate intelligent systems are based upon the existing mechanical and chemical support ones featured on space today, and especially on the ISS. The problem is set according to the characteristics presented at the Mars500 project, regarding the living quarters of six crew-members, along with their hygiene, leisure and eating areas. Transformable design techniques introduce spatial economy, adjustable zoning and increased efficiency within the interior, securing at the same time precise spatial orientation and character at any given time. The sensponsive configuration is

  14. Advanced Spacecraft Thermal Modeling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For spacecraft developers who spend millions to billions of dollars per unit and require 3 to 7 years to deploy, the LoadPath reduced-order (RO) modeling thermal...

  15. Spacecraft Cabin Particulate Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design, build and test an optical extinction monitor for the detection of spacecraft cabin particulates. This monitor will be sensitive to particle...

  16. Artist's drawing of Viking spacecraft

    Science.gov (United States)

    1973-01-01

    The National Aeronautics and Space Administration is developing an unmanned spacecraft called Viking to continue the exploration of Mars in the mid-1970s. Two Viking spacecraft, each including an orbiter and a lander will be launched by TitanIII/Centaur launch vehicles in August and September 1975 from Cape Kennedy to reach Mars in mid-1976. They will perform scientific investigations both from orbit and on the surface of Mars, including a search for life form on the planet.

  17. Four-spacecraft determination of magnetopause orientation, motion and thickness: comparison with results from single-spacecraft methods

    Directory of Open Access Journals (Sweden)

    S. E. Haaland

    2004-04-01

    Full Text Available In this paper, we use Cluster data from one magnetopause event on 5 July 2001 to compare predictions from various methods for determination of the velocity, orientation, and thickness of the magnetopause current layer. We employ established as well as new multi-spacecraft techniques, in which time differences between the crossings by the four spacecraft, along with the duration of each crossing, are used to calculate magnetopause speed, normal vector, and width. The timing is based on data from either the Cluster Magnetic Field Experiment (FGM or the Electric Field Experiment (EFW instruments. The multi-spacecraft results are compared with those derived from various single-spacecraft techniques, including minimum-variance analysis of the magnetic field and deHoffmann-Teller, as well as Minimum-Faraday-Residue analysis of plasma velocities and magnetic fields measured during the crossings. In order to improve the overall consistency between multi- and single-spacecraft results, we have also explored the use of hybrid techniques, in which timing information from the four spacecraft is combined with certain limited results from single-spacecraft methods, the remaining results being left for consistency checks. The results show good agreement between magnetopause orientations derived from appropriately chosen single-spacecraft techniques and those obtained from multi-spacecraft timing. The agreement between magnetopause speeds derived from single- and multi-spacecraft methods is quantitatively somewhat less good but it is evident that the speed can change substantially from one crossing to the next within an event. The magnetopause thickness varied substantially from one crossing to the next, within an event. It ranged from 5 to 10 ion gyroradii. The density profile was sharper than the magnetic profile: most of the density change occured in the earthward half of the magnetopause.

    Key words. Magnetospheric physics (magnetopause, cusp and

  18. The Geology of Mercury: The View Prior to the MESSENGER Mission

    Science.gov (United States)

    Head, James W.; Chapman, Clark R.; Domingue, Deborah L.; Hawkins, S. Edward; McClintock, William E.; Murchie, Scott L.; Prockter, Louise M.; Robinson, Mark S.; Strom, Robert G.; Watters, Thomas R.

    2007-08-01

    internally generated volcanic resurfacing may have ceased at ˜3.8 Ga; (5) a planet where impact craters can be used to disentangle the fundamental roles of gravity and mean impactor velocity in determining impact crater morphology and morphometry; (6) an environment where global impact crater counts can test fundamental concepts of the distribution of impactor populations in space and time; (7) an extreme environment in which highly radar-reflective polar deposits, much more extensive than those on the Moon, can be better understood; (8) an extreme environment in which the basic processes of space weathering can be further deduced; and (9) a potential end-member in terrestrial planetary body geological evolution in which the relationships of internal and surface evolution can be clearly assessed from both a tectonic and volcanic point of view. In the half-century since the launch of Sputnik, more than 30 spacecraft have been sent to the Moon, yet only now is a second spacecraft en route to Mercury. The MESSENGER mission will address key questions about the geologic evolution of Mercury; the depth and breadth of the MESSENGER data will permit the confident reconstruction of the geological history and thermal evolution of Mercury using new imaging, topography, chemistry, mineralogy, gravity, magnetic, and environmental data.

  19. Advanced LIGO and Multi-Messenger Transient Searches

    Science.gov (United States)

    Shawhan, Peter S.; LIGO Scientific Collaboration, Virgo Collaboration

    2016-01-01

    The first Advanced LIGO observing run, which began in September 2015, is on track to extend the volume*time reach of the gravitational wave (GW) detector network by an order of magnitude by the end of the year. Searches for transient GW signals from compact binary mergers and other possible sources are a central part of the LIGO-Virgo science program. To enhance those searches and to try to place any detected signals into an astronomical context, we have undertaken an extensive program of partnering with observers to enable prompt transient survey correlations and follow-up observations at all wavelengths, from optical and radio telescopes on the ground to astroparticle detectors to space missions including Fermi and Swift. I will summarize the data collected from the first Advanced LIGO observing run, the transient searches being carried out, and the multi-messenger observing effort.

  20. Tissue distribution of human acetylcholinesterase and butyrylcholinesterase messenger RNA

    Energy Technology Data Exchange (ETDEWEB)

    Jbilo, O.; Barteles, C.F.; Chatonnet, A.; Toutant, J.P.; Lockridge, O.

    1994-12-31

    Tissue distribution of human acetyicholinesterase and butyryicholinesterase messenger RNA. 1 Cholinesterase inhibitors occur naturally in the calabar bean (eserine), green potatoes (solanine), insect-resistant crab apples, the coca plant (cocaine) and snake venom (fasciculin). There are also synthetic cholinesterase inhibitors, for example man-made insecticides. These inhibitors inactivate acetyicholinesterase and butyrylcholinesterase as well as other targets. From a study of the tissue distribution of acetylcholinesterase and butyrylcholinesterase mRNA by Northern blot analysis, we have found the highest levels of butyrylcholinesterase mRNA in the liver and lungs, tissues known as the principal detoxication sites of the human body. These results indicate that butyrylcholinesterase may be a first line of defense against poisons that are eaten or inhaled.

  1. Messenger in The Barn: networking in a learning environment

    Directory of Open Access Journals (Sweden)

    Malcolm Rutter

    2009-12-01

    Full Text Available This case study describes the use of a synchronous communication application (MSN Messenger in a large academic computing environment. It draws on data from interviews, questionnaires and student marks to examine the link between use of the application and success measured through module marks. The relationship is not simple. Total abstainers and heavy users come out best, while medium level users do less well, indicating the influence of two factors. The discussion section suggests possible factors. The study also highlights the benefits of support and efficiency of communication that the application brings. Although there have been many studies of synchronous communication tool use in the office and in social life, this is one of the first to examine its informal use in an academic environment.

  2. Using an Instant Messenger to Learn a Foreign Language in a Peer-Tutoring Environment

    Science.gov (United States)

    Baek, Joeun; Yoo, Yungtai; Lee, Kyungsuk; Jung, Bokmoon; Baek, Youngkyun

    2017-01-01

    This study explores useful ways of using an instant messenger in a peer-tutoring environment when two students exchange their mother languages. Seven learners of Korean and seven Korean students learning English were paired randomly to conduct language exchange via an instant messenger, KakaoTalk. The pairs (five of male and female pair and two of…

  3. Nitric Oxide: The Coming of the Second Messenger

    Directory of Open Access Journals (Sweden)

    Ferid Murad

    2011-04-01

    Full Text Available (Excerpt The concept of communications between cells or cell signaling dates back over 100 years to Pavlov. He discovered that neuronal signals, first generated by the smell of food and later by the ringing of a bell, enhanced gastric secretion. The neurons communicated with cells in the stomach. Today it is well established that cell signaling is a universal phenomenon, occurring throughout the body and even between unicellular organisms such as yeast, fungi, and bacteria. The molecules that are used for the purpose of communicating between cells are diverse and comprise amino acids, peptides, proteins, and other organic molecules. These molecules, which number in the hundreds, were initially called “first messengers” and are now called hormones, cytokines, growth factors, paracrine substances, neurotransmitters, and a variety of other names. These molecules find their target cell by identifying and binding to a receptor that is mostly located on the surface of the target cell. This binding ensures the specificity of the interaction, since only cells with specific receptors will bind to specific ligands. The binding of the ligand to the receptor initiates a biochemical cascade, resulting in the accumulation of an intracellular second messenger, which then goes on to trigger the desired effect on the cell. The first second messenger, which was discovered in 1957, was cyclic adenosine monophosphate, or cAMP. Others came along in the ensuing 10–15 years. Today, we know there are many such molecules, including cyclic guanosine monophosphate (cGMP, nitric oxide (NO, calcium, diacylglycerol, phosphatidylinositols, and more, some surely yet to be discovered. Many of these discoveries eventually led to a Nobel Prize.

  4. An Educational Multimedia Presentation on the Introduction to Spacecraft Charging

    Science.gov (United States)

    Lin, E.; dePayrebrune, M.

    2004-01-01

    Over the last few decades, significant knowledge has been gained in how to protect spacecraft from charging; however, the continuing technical advancement in the design and build of satellites requires on-going effort in the study of spacecraft charging. A situation that we have encountered is that not all satellite designers and builders are familiar with the problem of spacecraft charging. The design of a satellite involves many talented people with diverse backgrounds, ranging from manufacturing and assembly to engineering and program management. The complex design and build of a satellite system requires people with highly specialized skills such that cross-specialization is often not achievable. As a result, designers and builders of satellites are not usually familiar with the problems outside their specialization. This is also true for spacecraft charging. Not everyone is familiar with the definition of spacecraft charging and the damage that spacecraft charging can cause. Understanding the problem is an important first step in getting everyone involved in addressing the appropriate spacecraft charging issues during the satellite design and build phases. To address this important first step, an educational multimedia presentation has been created to inform the general engineering community about the basics of spacecraft charging. The content of this educational presentation is based on relevant published technical papers. The presentation was developed using Macromedia Flash. This software produces a more dynamic learning environment than a typical slide show , resulting in a more effective learning experience. The end result is that the viewer will have learned about the basics of spacecraft charging. This presentation is available to the public through our website, www.dplscience.com, free of charge. Viewers are encouraged to pass this presentation to colleagues within their own work environment. This paper describes the content of the multimedia

  5. Spacecraft Crew Cabin Condensation Control

    Science.gov (United States)

    Carrillo, Laurie Y.; Rickman, Steven L.; Ungar, Eugene K.

    2013-01-01

    A report discusses a new technique to prevent condensation on the cabin walls of manned spacecraft exposed to the cold environment of space, as such condensation could lead to free water in the cabin. This could facilitate the growth of mold and bacteria, and could lead to oxidation and weakening of the cabin wall. This condensation control technique employs a passive method that uses spacecraft waste heat as the primary wallheating mechanism. A network of heat pipes is bonded to the crew cabin pressure vessel, as well as the pipes to each other, in order to provide for efficient heat transfer to the cabin walls and from one heat pipe to another. When properly sized, the heat-pipe network can maintain the crew cabin walls at a nearly uniform temperature. It can also accept and distribute spacecraft waste heat to maintain the pressure vessel above dew point.

  6. Conductive spacecraft materials development program

    Science.gov (United States)

    Lehn, W. L.

    1977-01-01

    The objectives of this program are to provide design criteria, techniques, materials, and test methods to ensure control of absolute and differential charging of spacecraft surfaces. The control of absolute and differential charging of spacecraft cannot be effected without the development of new and improved or modified materials or techniques that will provide electrical continuity over the surface of the spacecraft. The materials' photoemission, secondary emission, thermooptical, physical, and electrical properties in the space vacuum environment both in the presence and absence of electrical stress and ultraviolet, electron, and particulate radiation, are important to the achievement of charge control. The materials must be stable or have predictable response to exposure to the space environment for long periods of time. The materials of interest include conductive polymers, paints, transparent films and coatings as well as fabric coating interweaves.

  7. How to feed a spacecraft

    Science.gov (United States)

    Mclaughlin, William

    1987-01-01

    The uplink process between ground computers and the spacecraft computer is examined. Data is uplinked to a spacecraft by a load (a sequence of preplanned commands) or by real-time commands; the differences between these two types of uplinks are discussed. The sequencing of a load involves: (1) request generation, (2) request integration, (3) reference generation, and (4) transmitting the load. The functions of each of the sequencing steps are described. The development of new sequencing methods using expert systems and AI is being studied. A symbolic processing software which has the ability to transmit data typed into a computer in English was developed. Consideration is given to the composition, capabilities of the parser, and application of the symbolic processing software to the Comet Renedezvous Asteroid Flyby spacecraft.

  8. Concurrent rendezvous control of underactuated spacecraft

    Science.gov (United States)

    Muralidharan, Vijay; Reza Emami, M.

    2017-09-01

    The concurrent control of spacecraft equipped with one-axis unilateral thruster and three-axis attitude actuator is considered in this paper. The proposed control law utilizes attitude control channels along with the single thrust force concurrently, for three-dimensional trajectory tracking and rendezvous with a target object. The concurrent controller also achieves orbital transfer to low Earth orbits with long range separation. To demonstrate the orbit transfer capabilities of the concurrent controller, a smooth elliptical orbit transfer trajectory for co-planar circular orbits is designed. The velocity change and energy consumption of the designed orbit transfer trajectory is observed to be equivalent to that of Hohmann transfer.

  9. A corrector for spacecraft calculated electron moments

    Directory of Open Access Journals (Sweden)

    J. Geach

    2005-03-01

    Full Text Available We present the application of a numerical method to correct electron moments calculated on-board spacecraft from the effects of potential broadening and energy range truncation. Assuming a shape for the natural distribution of the ambient plasma and employing the scalar approximation, the on-board moments can be represented as non-linear integral functions of the underlying distribution. We have implemented an algorithm which inverts this system successfully over a wide range of parameters for an assumed underlying drifting Maxwellian distribution. The outputs of the solver are the corrected electron plasma temperature Te, density Ne and velocity vector Ve. We also make an estimation of the temperature anisotropy A of the distribution. We present corrected moment data from Cluster's PEACE experiment for a range of plasma environments and make comparisons with electron and ion data from other Cluster instruments, as well as the equivalent ground-based calculations using full 3-D distribution PEACE telemetry.

  10. WhatsApp Messenger is useful and reproducible in the assessment of tibial plateau fractures: inter- and intra-observer agreement study.

    Science.gov (United States)

    Giordano, Vincenzo; Koch, Hilton Augusto; Mendes, Carlos Henrique; Bergamin, André; de Souza, Felipe Serrão; do Amaral, Ney Pecegueiro

    2015-02-01

    The aim of this study was to evaluate the inter- and intra-observer agreement in the initial diagnosis and classification by means of plain radiographs and CT scans of tibial plateau fractures photographed and sent via WhatsApp Messenger. The increasing popularity of smartphones has driven the development of technology for data transmission and imaging and generated a growing interest in the use of these devices as diagnostic tools. The emergence of WhatsApp Messenger technology, which is available for various platforms used by smartphones, has led to an improvement in the quality and resolution of images sent and received. The images (plain radiographs and CT scans) were obtained from 13 cases of tibial plateau fractures using the iPhone 5 (Apple Inc., Cupertino, CA, USA) and were sent to six observers via the WhatsApp Messenger application. The observers were asked to determine the standard deviation and type of injury, the classification according to the Schatzker and the Luo classifications schemes, and whether the CT scan changed the classification. The six observers independently assessed the images on two separate occasions, 15 days apart. The inter- and intra-observer agreement for both periods of the study ranged from excellent to perfect (0.75WhatsApp Messenger. The authors now propose the systematic use of the application to facilitate faster documentation and obtaining the opinion of an experienced consultant when not on call. Finally, we think the use of the WhatsApp Messenger as an adjuvant tool could be broadened to other clinical centres to assess its viability in other skeletal and non-skeletal trauma situations. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  11. Spacecraft thermal control coatings

    Science.gov (United States)

    Guillaumon, Jean-Claude; Paillous, Alain

    1992-01-01

    The Experiment AO 138-6 was located on the trailing edge of the Long Duration Exposure Facility as part of the French Cooperative Payload (FRECOPA) Experiment. It was purely passive in nature: material specimens 2 x 2 cm, independently mounted in sample-holders, with their surface in the same reference plane, were exposed to space. Thirty samples were set in a vacuum-tight canister which was opened in space a few days after LDEF deployment and closed while still in orbit ten months later; twenty-four samples were directly exposed to space for the total flight duration (preflight handling, shuttle bay environment, separation from shuttle, shuttle environment, LEO environment, docking, descent, transfer to KSC). Materials included paints (conductive or nonconductive), SSM's, polymeric films, surface coatings, composite materials, and metals. After sample retrieving, inspection and measurements were carried out in atmospheric laboratory conditions on each sample: observation with binocular lenses and scanning electron microscopy, spectral relectance and transmittance using an integrating sphere in the wavelength range 280-2300 nm, emissivity by the means of a Gier & Dunkle portable reflectometer, electron spectroscopy for chemical analysis-x-ray photoelectron spectroscopy (ESCA-XPS), and Rutherford backscattering spectroscopy (RBS) measurements on some selected samples. The results obtained from flight were compared to laboratory data obtained in UV-irradiation tests when these data were available. As a general statement a good spectral concordance is observed for all samples not in the canister so long as air recoveries are taken into account. For one material, the degradation is more important for the sample in the canister than for those of the same material mounted at the surface of the tray; for most samples in the canister the degradation is slightly higher than the one which can be predicted from laboratory standard irradiations. Contamination problems having

  12. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    -term plans for their analytical tools, in this case to take breath analysis away from the large complex instruments in the laboratory to the outpatient clinic and eventually to the home care market. Similarly, for environmental and public health research, it is always desirable to have easily operated and deployable instruments that can be taken to the field, rather than bringing numerous subjects to a central laboratory. Bio-monitoring. Although the SAMAP community is much more focused on air rather than breath measurement, this is changing because of the realization that longer deployment times (on submarines and spacecraft) will affect more than just acute health. To monitor longer-term health outcomes, there is a great deal of commonality between our respective research communities. Any instrument that monitors for contaminants in environmental air could certainly be adapted to breath analysis for assessing exposures and health state. Instruments that simultaneously provide rapid response and high specificity to a broad range of analytes, such as those based on optical spectroscopy and mass spectrometry, are particularly valued. The path forward We found the SAMAP meeting to be a worthwhile experience, largely from the discovery that another high-tech community exists with similar needs as the IABR community. Some collaboration could be fruitful for us; we suggest that the IABR community stay in contact with SAMAP in the future and attempt to attend each other's meetings if possible. SAMAP meetings tend to run on a two year cycle and so the next one has not yet been announced. We will let the IABR community know when the next meeting is scheduled, and will certainly make the SAMAP people aware of IABR meetings and the Journal of Breath Research. This article has been subjected to EPA Agency review and approved for publication. Statements do not necessarily reflect official Agency policy.

  13. Radiation Environment Effects on Spacecraft

    Science.gov (United States)

    Ladbury, Ray.

    2017-01-01

    Space poses a variety of radiation hazards. These hazards pose different risks for different missions depending on the mission environment, duration and requirements. This presentation presents a brief look at several radiation related hazards, including destructive and nondestructive Single-Event Effect, Total Ionizing Dose, Displacement Damage and Spacecraft Charging. The temporal and spatial characteristics for the environments of concern for each are considered.

  14. Optimal Reorientation Of Spacecraft Orbit

    Directory of Open Access Journals (Sweden)

    Chelnokov Yuriy Nikolaevich

    2014-06-01

    Full Text Available The problem of optimal reorientation of the spacecraft orbit is considered. For solving the problem we used quaternion equations of motion written in rotating coordinate system. The use of quaternion variables makes this consideration more efficient. The problem of optimal control is solved on the basis of the maximum principle. An example of numerical solution of the problem is given.

  15. Mesh Network Architecture for Enabling Inter-Spacecraft Communication

    Science.gov (United States)

    Becker, Christopher; Merrill, Garrick

    2017-01-01

    To enable communication between spacecraft operating in a formation or small constellation, a mesh network architecture was developed and tested using a time division multiple access (TDMA) communication scheme. The network is designed to allow for the exchange of telemetry and other data between spacecraft to enable collaboration between small spacecraft. The system uses a peer-to-peer topology with no central router, so that it does not have a single point of failure. The mesh network is dynamically configurable to allow for addition and subtraction of new spacecraft into the communication network. Flight testing was performed using an unmanned aerial system (UAS) formation acting as a spacecraft analogue and providing a stressing environment to prove mesh network performance. The mesh network was primarily devised to provide low latency, high frequency communication but is flexible and can also be configured to provide higher bandwidth for applications desiring high data throughput. The network includes a relay functionality that extends the maximum range between spacecraft in the network by relaying data from node to node. The mesh network control is implemented completely in software making it hardware agnostic, thereby allowing it to function with a wide variety of existing radios and computing platforms..

  16. Results and prospects in multi-messenger particle astrophysics

    Science.gov (United States)

    Mostafa, Miguel

    2017-01-01

    In high-energy particle astrophysics the old days were certainly not better than these. Our field has thrived in the past decade with experiments covering thousands of square kilometers to measure the suppression in the flux of the highest energy cosmic rays ever observed, instrumenting a cubic kilometer of Antarctic ice to discover astrophysical neutrinos, and measuring a change in arm length as small as 10-19 m for the ground-breaking direct observation of gravitational waves. Additionally, the current generation of space-borne and ground-based gamma-ray experiments have revealed a plethora of gamma-ray sources, including pulsars, compact binaries, the galactic center, and extragalactic sources such as starburst galaxies and radio galaxies. Before the next generation of instruments bring us yet another order of magnitude in sensitivity, we can combine current observations to probe physics beyond the standard model, and to extend the high-energy frontier well above the energies accessible to laboratory accelerators. One example of this potential is the search for dark-matter annihilation and decay products. To use the multi-messenger approach effectively for probing dark-matter signatures and physics beyond the LHC energy requires understanding the origin (or acceleration mechanism) and the propagation processes. High energy protons and nuclei, neutrinos, gamma-rays, X-rays, and gravitational waves bring new and complementary views of the astrophysical sources. By comparing observations through different windows, we can use the sites of violent phenomena as a laboratory to probe the physical processes under extreme conditions throughout the Universe, and to test the fundamental laws of particle physics and gravitation. As a community we need to engage in a bold synergistic approach to understanding the violent processes that give rise to the high-energy cosmic phenomena in the Universe. In this invited talk, I will present on-going multi-messenger studies to

  17. Materials for Spacecraft. Chapter 6

    Science.gov (United States)

    Finckenor, Miria M.

    2016-01-01

    The general knowledge in this chapter is intended for a broad variety of spacecraft: manned or unmanned, low Earth to geosynchronous orbit, cis-lunar, lunar, planetary, or deep space exploration. Materials for launch vehicles are covered in chapter 7. Materials used in the fabrication of spacecraft hardware should be selected by considering the operational requirements for the particular application and the design engineering properties of the candidate materials. The information provided in this chapter is not intended to replace an in-depth materials study but rather to make the spacecraft designer aware of the challenges for various types of materials and some lessons learned from more than 50 years of spaceflight. This chapter discusses the damaging effects of the space environment on various materials and what has been successfully used in the past or what may be used for a more robust design. The material categories covered are structural, thermal control for on-orbit and re-entry, shielding against radiation and meteoroid/space debris impact, optics, solar arrays, lubricants, seals, and adhesives. Spacecraft components not directly exposed to space must still meet certain requirements, particularly for manned spacecraft where toxicity and flammability are concerns. Requirements such as fracture control and contamination control are examined, with additional suggestions for manufacturability. It is important to remember that the actual hardware must be tested to understand the real, "as-built" performance, as it could vary from the design intent. Early material trades can overestimate benefits and underestimate costs. An example of this was using graphite/epoxy composite in the International Space Station science racks to save weight. By the time the requirements for vibration isolation, Space Shuttle frequencies, and experiment operations were included, the weight savings had evaporated.

  18. Nonthermal electromagnetic fields: from first messenger to therapeutic applications.

    Science.gov (United States)

    Pilla, Arthur A

    2013-06-01

    Nonthermal pulsed electromagnetic fields, from low frequency to pulse-modulated radio frequency, have been successfully employed as adjunctive therapy for the treatment of delayed and non-union fractures, fresh fractures and chronic wounds. Recent increased understanding of the mechanism of action of electromagnetic fields (EMF) has permitted technologic advances allowing the development of EMF devices which are portable and disposable, can be incorporated into dressings, supports and casts, and can be used over clothing. This broadens the use of non-pharmacological, non-invasive EMF therapy to the treatment of postoperative pain and edema to enhance surgical recovery. EMF therapy is rapidly becoming a standard part of surgical care, and new, more significant, clinical applications for osteoarthritis, brain and cardiac ischemia and traumatic brain injury are in the pipeline. This study reviews recent evidence which suggests that calmodulin (CaM)-dependent nitric oxide signaling is involved in cell and tissue response to weak nonthermal EMF signals. There is abundant evidence that EMF signals can be configured a priori to increase the rate of CaM activation, which, in turn, can modulate the biochemical cascades living cells and tissues employ in response to external insult. Successful applications in pilot clinical trials, coupled with evidence at the cellular and animal levels, provide support that EMF is a first messenger that can modulate the response of challenged biological systems.

  19. Photoaffinity labeling of the messenger RNA cap-binding protein

    Energy Technology Data Exchange (ETDEWEB)

    Rhoads, R.; Patzelt, E.; Blaas, D.; Kuechler, E.

    1986-05-01

    A photoaffinity derivative of a cap analogue, ..gamma..(/sup 32/P)-(4-(benzoylphenyl)methylamido)-7-methylguanosine 5'-triphosphate, was reacted with the 28-kDa messenger RNA cap-binding protein (CBP), purified by affinity chromatography from rabbit erythrocyte lysate. The predominant labeling was of the 28-kDa species. No labeling occurred without photoillumination or in the presence of 250 ..mu..M m/sup 7/GTP. In addition CBP, two polypeptides of 19 and 17kDa, present in the affinity-purified preparation, were specifically labeled. Another sample tested was the eIF-3 region of a sucrose gradient fractionation, in 100 mM KCl, of rabbit reticulocyte high salt ribosomal wash. The only polypeptide labeled was the 28-kDa CBP. Labeling was more intense than with an equivalent amount of affinity-purified CBP, suggesting the presence of stabilizing or stimulatory factors in the eIF-3 preparation.

  20. Internet messenger based smart virtual class learning using ubiquitous computing

    Science.gov (United States)

    Umam, K.; Mardi, S. N. S.; Hariadi, M.

    2017-06-01

    Internet messenger (IM) has become an important educational technology component in college education, IM makes it possible for students to engage in learning and collaborating at smart virtual class learning (SVCL) using ubiquitous computing. However, the model of IM-based smart virtual class learning using ubiquitous computing and empirical evidence that would favor a broad application to improve engagement and behavior are still limited. In addition, the expectation that IM based SVCL using ubiquitous computing could improve engagement and behavior on smart class cannot be confirmed because the majority of the reviewed studies followed instructions paradigms. This article aims to present the model of IM-based SVCL using ubiquitous computing and showing learners’ experiences in improved engagement and behavior for learner-learner and learner-lecturer interactions. The method applied in this paper includes design process and quantitative analysis techniques, with the purpose of identifying scenarios of ubiquitous computing and realize the impressions of learners and lecturers about engagement and behavior aspect and its contribution to learning

  1. Topicality and impact in social media: diverse messages, focused messengers.

    Directory of Open Access Journals (Sweden)

    Lilian Weng

    Full Text Available We have a limited understanding of the factors that make people influential and topics popular in social media. Are users who comment on a variety of matters more likely to achieve high influence than those who stay focused? Do general subjects tend to be more popular than specific ones? Questions like these demand a way to detect the topics hidden behind messages associated with an individual or a keyword, and a gauge of similarity among these topics. Here we develop such an approach to identify clusters of similar hashtags in Twitter by detecting communities in the hashtag co-occurrence network. Then the topical diversity of a user's interests is quantified by the entropy of her hashtags across different topic clusters. A similar measure is applied to hashtags, based on co-occurring tags. We find that high topical diversity of early adopters or co-occurring tags implies high future popularity of hashtags. In contrast, low diversity helps an individual accumulate social influence. In short, diverse messages and focused messengers are more likely to gain impact.

  2. Topicality and impact in social media: diverse messages, focused messengers.

    Science.gov (United States)

    Weng, Lilian; Menczer, Filippo

    2015-01-01

    We have a limited understanding of the factors that make people influential and topics popular in social media. Are users who comment on a variety of matters more likely to achieve high influence than those who stay focused? Do general subjects tend to be more popular than specific ones? Questions like these demand a way to detect the topics hidden behind messages associated with an individual or a keyword, and a gauge of similarity among these topics. Here we develop such an approach to identify clusters of similar hashtags in Twitter by detecting communities in the hashtag co-occurrence network. Then the topical diversity of a user's interests is quantified by the entropy of her hashtags across different topic clusters. A similar measure is applied to hashtags, based on co-occurring tags. We find that high topical diversity of early adopters or co-occurring tags implies high future popularity of hashtags. In contrast, low diversity helps an individual accumulate social influence. In short, diverse messages and focused messengers are more likely to gain impact.

  3. Spacecraft Charge as a Source of Electrical Power for Spacecraft

    Science.gov (United States)

    1988-11-01

    Limitations ............ . . 7.2 Appendix : MATHCAD 2.0 Document for Solving Spacecraft Charging Equations . . . APP.1 Bibliography...The charging model is solved using the equation solver routines in MATHCAD 2.0: an engineering computer software package by MathSoft Inc. The Appendix...lists the problem formulated as a MATHCAD document. The 3 output data from MATHCAD 2.0 has been graphed using the spreadsheet QUATTRO by Borland. 3

  4. Quick Spacecraft Thermal Analysis Tool Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For spacecraft design and development teams concerned with cost and schedule, the Quick Spacecraft Thermal Analysis Tool (QuickSTAT) is an innovative software suite...

  5. Service Oriented Spacecraft Modeling Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The I-Logix team proposes development of the Service Oriented Spacecraft Modeling Environment (SOSME) to allow faster and more effective spacecraft system design...

  6. De regreso al origen? La escritura simbolica y el lenguaje escrito en los usuarios del Messenger

    National Research Council Canada - National Science Library

    Valencia-Cerino, Yaditzy; Garcia-Martinez, Veronica

    2009-01-01

    El presente estudio es el resultado de un trabajo de tesis de comunicacion en el que se aborda el tema de la utilizacion del lenguaje en el Messenger y sus posibles repercusiones en los manuscritos...

  7. MESSENGER E/V/H MASCS 5 VIRS DERIVED ANALYSIS DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER MASCS VIRS derived analysis product, also known as the DAP. The DAP is a 500 meter per pixel mosaic map of...

  8. MESSENGER E/V/H MASCS 2 VIRS UNCALIBRATED DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER MASCS VIRS uncalibrated observations, also known as EDRs. The MASCS VIRS experiment is a fixed concave...

  9. MESSENGER V/H RADIO SCIENCE SUBSYSTEM 1 EDR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains archival raw, partially processed, and ancillary/supporting radio science data acquired during the MESSENGER mission. The radio observations...

  10. MESSENGER H XRS 5 REDUCED DATA RECORD (RDR) FOOTPRINTS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER XRS reduced data record (RDR) footprints which are derived from the navigational meta-data for each...

  11. MESSENGER E/V/H MASCS 3 UVVS CALIBRATED DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER MASCS UVVS calibrated observations, also known as CDRs. The MASCS UVVS experiment is a scanning grating...

  12. MESSENGER E/V/H XRS CALIBRATED (CDR) SPECTRA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER XRS calibrated observations, also known as CDRs. Each XRS observation results in four X-ray spectra. When...

  13. MESSENGER E/V/H MASCS 3 VIRS CALIBRATED DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER MASCS VIRS calibrated observations, also known as CDRs. The MASCS VIRS experiment is a fixed concave...

  14. MESSENGER E/V/H/SW EPPS CALIBRATED EPS DDR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Energetic Particle and Plasma Spectrometer (EPPS) advanced data products, also known as DDR/DAPs. The...

  15. MESSENGER E/V/H GRNS 3 GAMMA RAY SPECTROMETER CALIBDATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER GRS calibrated observations (CDRs) and the reduced data product (RDR). The GRS experiment is a gamma ray...

  16. MESSENGER E/V/H GRNS 2 GAMMA RAY SPECTROMETER RAW DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER GRS uncalibrated observations, also known as EDRs. The GRS experiment is a gamma ray spectrometer designed...

  17. Energy Storage Flywheels on Spacecraft

    Science.gov (United States)

    Bartlett, Robert O.; Brown, Gary; Levinthal, Joel; Brodeur, Stephen (Technical Monitor)

    2002-01-01

    With advances in carbon composite material, magnetic bearings, microprocessors, and high-speed power switching devices, work has begun on a space qualifiable Energy Momentum Wheel (EMW). An EMW is a device that can be used on a satellite to store energy, like a chemical battery, and manage angular momentum, like a reaction wheel. These combined functions are achieved by the simultaneous and balanced operation of two or more energy storage flywheels. An energy storage flywheel typically consists of a carbon composite rotor driven by a brushless DC motor/generator. Each rotor has a relatively large angular moment of inertia and is suspended on magnetic bearings to minimize energy loss. The use of flywheel batteries on spacecraft will increase system efficiencies (mass and power), while reducing design-production time and life-cycle cost. This paper will present a discussion of flywheel battery design considerations and a simulation of spacecraft system performance utilizing four flywheel batteries to combine energy storage and momentum management for a typical LEO satellite. A proposed set of control laws and an engineering animation will also be presented. Once flight qualified and demonstrated, space flywheel batteries may alter the architecture of most medium and high-powered spacecraft.

  18. Crosstalk between secondary messengers, hormones and MAPK modules during abiotic stress signalling in plants.

    Science.gov (United States)

    Smékalová, Veronika; Doskočilová, Anna; Komis, George; Samaj, Jozef

    2014-01-01

    The crosstalk between second messengers, hormones and mitogen-activated protein kinases (MAPKs) in plant signalling systems facilitates adaptation and survival in the face of diverse environmental stresses. This review focuses on the transduction of second messenger and hormone signals by MAPK modules in plant abiotic stress responses. We discuss how this crosstalk regulates gene expression (e.g. by controlling transcription factor activity) and other cellular and physiological responses to enable adaptation and/or resistance to abiotic stresses. © 2013.

  19. Test for consistence of a flyby anomaly simulation with the observed Doppler residuals for the Messenger flybys of Mercury

    CERN Document Server

    Busack, Hans-Juergen

    2010-01-01

    In 2007, the observed Earth flyby anomalies have been successfully simulated using an empirical formula (H. J. Busack, 2007). This simulation has led to the prediction of anomaly values, to be expected for the Rosetta flybys of Mars in 2007, and following twice of Earth in 2007 and 2009. While the data for the Mars flyby are yet under evaluation, the predictions of the formula for the last two Earth flybys of Rosetta are fully confirmed now. This is remarkable, since an alternatively proposed formula (Anderson et al., 2007) failed to predict the correct values for the recent flybys. For the Mercury flybys of the Messenger spacecraft, this alternative formula predicts a null result. In the meantime, Doppler residuals of these flybys on 14.01.2008 and 06.10.2008 are availabel. On both flybys, significant residuals were observed, using gravity data derived by Mariner 10 on Mercury (D. E. Smith et al., 2009). According to the authors, these residuals cannot be eliminated totally by adjustment of the second degree...

  20. Spacecraft and their Boosters. Aerospace Education I.

    Science.gov (United States)

    Coard, E. A.

    This book, one in the series on Aerospace Education I, provides a description of some of the discoveries that spacecraft have made possible and of the experience that American astronauts have had in piloting spacecraft. The basic principles behind the operation of spacecraft and their boosters are explained. Descriptions are also included on…

  1. Opioid modulation of immunocompetence: Receptor characterization and second messenger involvement

    Energy Technology Data Exchange (ETDEWEB)

    Hemmick, L.M.

    1989-01-01

    The purpose of this thesis was to examine the effects of opioids on several indices of immunocompetence, determined the receptor specificity of these effects, and ascertain whether the actions of opioids on lymphocytes could be correlated with activation of second messenger systems. By measuring {sup 45}Ca{sup 2+} uptake into lymphocytes, it was demonstrated that {beta}-endorphin 1-31 ({beta}-END 1-31) enhanced rat thymocyte Ca{sup 2+} uptake in response to concanavalin A (Con A) but not phytohemagglutinin (PHA). Related opioid peptides and alkaloids were unable to mimic the effect, and naloxone did not block it, suggesting that {beta}-END 1-31 acted by binding to specific, non-opioid receptors on the thymocytes. Rat splenocyte Con A-stimulated Ca{sup 2+} uptake was not affected by {beta}-END 1-31. {beta}-END 1-31 did not affect basal Ca{sup 2+} uptake by either cell type. Using ({sup 3}H)thymidine uptake as an index of lymphocyte proliferation, {beta}-END 1-31 and several related opioid peptides reversed prostaglandin E{sub 1} (PGE{sub 1}) suppression of rat lymph node cell Con A- and PHA-stimulated proliferation. Naloxone did not block the reversal. {beta}-END 1-31 was unable to reverse forskolin and cholera toxin suppression of proliferation, indicating that the lowering of cyclic AMP levels was not the mechanism involved. Verapamil inhibition of proliferation was also not reversed by {beta}-END 1-31, suggesting that promotion of Ca{sup 2+} influx was not a major mechanism involved.

  2. Mercury surface composition: how the new insights from MESSENGER can drive the future exploration

    Science.gov (United States)

    Carli, Cristian; Capaccioni, Fabrizio; Filacchione, Gianrico; Zambon, Francesca; Serventi, Giovanna; Altieri, Francesca; De Sanctis, MariaCristina; Sgavetti, Maria

    2016-04-01

    The surface composition of Mercury, as well as the relationship between morphological expressions and lithologies, is one of the most interesting goal to be still explored. After Mariner10, despite relevant differences observed in geophysical characteristics, Mercury surface composition was compared to the Moon (Murray et al, 1974, Science), and, subsequently, lunar surface was considered as analogue (e.g., Blewett et al., 2002, Meteor.Planet.Sci.). After MESSENGER, Mercury surface appeared mainly volcanic in origin. Plains (intercrater and smooth) seem to have a primary flood effusive origin, and even cratered terrains could have the same origin with a higher crater concentration. These volcanic units range from high reflectance red plains to low reflectance blue plains (Denevi et al., 2009, Science). No absorption is present in the visible and near-infrared spectra, indicating very low abundance of transitional elements in silicates (i.e. very low iron and titanium, e.g. FeO < 1%, Klima et al., 2014, Whispers). XRS and GRS, onboard MESSENGER, confirmed a very low Fe/Si ratio in the surface material (Weider et al., 2014, Icarus), not only in silicates, differently from the volcanic compositions present in all the other planetary surfaces. K, Th, U GRS-based are consistent with chondritic source but with greater volatile abundances (Peplowski et al., 2011, Science; 2012, JGR). Moreover, XRS measured high volatile abundances (i.e., S, Na, K) (Evans et al., 2012, JGR; Weider et al., 2012, JGR), with a variable distribution on the surface. The presence of high level of volatiles is in agreement with the evidence of pyroclastic materials (Kerber et al., 2009, EPSL). Mg/Si shows relative high values, with a high variability on the surface. Higher values of Mg/Si are detected in some terrains related to high concentration of Ca/Si, and low Al/Si, indicating ultramafic composition, a relative high degree of partial melting and high temperature, in particular in older

  3. Structural Dynamic Analysis of a Spacecraft Multi-DOF Shaker Table

    Science.gov (United States)

    Pray, Carl; Blelloch, Paul; Thomas, Gareth; McNelis, Mark; Suarez, Vicente; Otten, Kim

    2008-01-01

    Finite element enforced response analysis was performed on a three axis expander head shaker table to aid in the design of the table structure and vibration control system. The payload for this shaker system is a generic spacecraft with a multitude of flexible modes across a broad frequency band. A Craig-Bampton representation of the spacecraft was used to expedite analysis of multiple shaker table designs. The analysis examines the required forces in the actuators for a constant amplitude base acceleration sine sweep test, the resulting forces in the spacecraft and table attachment restraints, and the resulting accelerations on the spacecraft structure. The results show the spacecraft response is very high at the spacecraft center of gravity (CG) due to the high CG offset and cantilever effect of the low frequency spacecraft bending modes. The high response can be addressed by "notching" the input vibration levels to avoid over-testing the spacecraft. At frequencies above 25 Hz, the spacecraft modal effective masses are very small, and the response of the shaker table dominates the response. Anti-resonances of the shaker table in the frequency range of interest reduce the acceleration output and require much higher actuator forces to achieve the acceleration specification. These effects may require stiffening the shaker structure to move the modes out of the test frequency range or increasing the shaker table damping.

  4. An Overview of Ultraviolet Through Infrared Reflectance Spectroscopic Observations of Mercury During the First MESSENGER Flyby

    Science.gov (United States)

    Izenberg, N. R.; McClintock, W. E.; Holsclaw, G. M.; Robinson, M. S.; Blewett, D. T.; Domingue, D. L.; Head, J. W.; Jensen, E. A.; Kochte, M. C.; Lankton, M. R.; Murchie, S. L.; Sprague, A. L.; Vilas, F.; Solomon, S. C.

    2008-05-01

    During the first MESSENGER flyby of Mercury on January 14, 2008, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) measured reflectance spectra from Mercury's surface over the wavelength range 220-1450 nm. These are the first high-spatial-resolution (Mozart crater and in Tir Planitia. Ground-based observations of Mercury reveal a surface with a red, nearly featureless spectrum in the visible and near-infrared (wavelengths greater than ~ 500 nm) that has been interpreted as evidence for a largely iron-poor feldspathic composition. Initial analyses of VIRS spectra also show strongly red-sloped, near featureless spectra, appearing to support contentions of low iron abundance in surface materials. However, interpretation of Mercury's spectral reflectance is complicated by our lack of knowledge about the effects on its surface materials of space weathering, which both suppresses the strength of spectral absorption features and reddens the spectrum. Brightness variations and absorption bands in ultraviolet reflectance may help determine both the nature and extent of processes that modify observed reflectance at longer wavelengths. MASCS surface observation data demonstrate spectral variations across the Mercury surface that can be related to previous telescopic observations, compared and contrasted with lunar observations, and linked to possible influences of space weathering.

  5. Statistical study of ICME effects on Mercury's magnetospheric boundaries and northern cusp region from MESSENGER

    Science.gov (United States)

    Winslow, Reka M.; Philpott, Lydia; Paty, Carol S.; Lugaz, Noé; Schwadron, Nathan A.; Johnson, Catherine L.; Korth, Haje

    2017-05-01

    This paper presents a systematic investigation of the large-scale processes in Mercury's magnetosphere during interplanetary coronal mass ejections (ICMEs) using observations from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. We study the motion of the bow shock and magnetopause boundaries, quantify the magnetospheric compression, and characterize the size, extent, and plasma pressure of the northern cusp region and the plasma precipitation to the surface. During ICMEs, the magnetopause was substantially compressed, as the subsolar standoff distance from the center of the planet was reduced by ˜15% compared with the value during nominal solar wind conditions, and the magnetopause reached the surface of the planet ˜30% of the time. On the other hand, the bow shock under ICME conditions was located farther from the planet than for nominal solar wind conditions. The cusp was observed to extend ˜10° farther equatorward and 2 h wider in local time. In addition, the average plasma pressure in the cusp was more than double that determined under nominal conditions. For the most extreme cases, the particle precipitation to the surface was an order of magnitude higher than on average. The solar wind ram pressure and the Alfvén Mach number are found to be the dominant factors affecting these changes in the magnetosphere, with the interplanetary magnetic field (IMF) direction and the IMF magnetic pressure playing a small but likely nonnegligible role.

  6. Nuclease escape elements protect messenger RNA against cleavage by multiple viral endonucleases.

    Science.gov (United States)

    Muller, Mandy; Glaunsinger, Britt A

    2017-08-01

    During lytic Kaposi's sarcoma-associated herpesvirus (KSHV) infection, the viral endonu- clease SOX promotes widespread degradation of cytoplasmic messenger RNA (mRNA). However, select mRNAs, including the transcript encoding interleukin-6 (IL-6), escape SOX-induced cleavage. IL-6 escape is mediated through a 3' UTR RNA regulatory element that overrides the SOX targeting mechanism. Here, we reveal that this protective RNA element functions to broadly restrict cleavage by a range of homologous and non-homologous viral endonucleases. However, it does not impede cleavage by cellular endonucleases. The IL-6 protective sequence may be representative of a larger class of nuclease escape elements, as we identified a similar protective element in the GADD45B mRNA. The IL-6 and GADD45B-derived elements display similarities in their sequence, putative structure, and several associated RNA binding proteins. However, the overall composition of their ribonucleoprotein complexes appears distinct, leading to differences in the breadth of nucleases restricted. These findings highlight how RNA elements can selectively control transcript abundance in the background of widespread virus-induced mRNA degradation.

  7. Solar system expansion and strong equivalence principle as seen by the NASA MESSENGER mission

    Science.gov (United States)

    Genova, Antonio; Mazarico, Erwan; Goossens, Sander; Lemoine, Frank G.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.

    2018-01-01

    The NASA MESSENGER mission explored the innermost planet of the solar system and obtained a rich data set of range measurements for the determination of Mercury's ephemeris. Here we use these precise data collected over 7 years to estimate parameters related to general relativity and the evolution of the Sun. These results confirm the validity of the strong equivalence principle with a significantly refined uncertainty of the Nordtvedt parameter η = (-6.6 ± 7.2) × 10-5. By assuming a metric theory of gravitation, we retrieved the post-Newtonian parameter β = 1 + (-1.6 ± 1.8) × 10-5 and the Sun's gravitational oblateness, J2⊙J2⊙ = (2.246 ± 0.022) × 10-7. Finally, we obtain an estimate of the time variation of the Sun gravitational parameter, GM⊙°/GM⊙GM⊙°/GM⊙ = (-6.13 ± 1.47) × 10-14, which is consistent with the expected solar mass loss due to the solar wind and interior processes. This measurement allows us to constrain ∣∣G°∣∣/GG°/G to be <4 × 10-14 per year.

  8. Model of spacecraft atomic oxygen and solar exposure microenvironments

    Science.gov (United States)

    Bourassa, R. J.; Pippin, H. G.

    1993-01-01

    Computer models of environmental conditions in Earth orbit are needed for the following reasons: (1) derivation of material performance parameters from orbital test data, (2) evaluation of spacecraft hardware designs, (3) prediction of material service life, and (4) scheduling spacecraft maintenance. To meet these needs, Boeing has developed programs for modeling atomic oxygen (AO) and solar radiation exposures. The model allows determination of AO and solar ultraviolet (UV) radiation exposures for spacecraft surfaces (1) in arbitrary orientations with respect to the direction of spacecraft motion, (2) overall ranges of solar conditions, and (3) for any mission duration. The models have been successfully applied to prediction of experiment environments on the Long Duration Exposure Facility (LDEF) and for analysis of selected hardware designs for deployment on other spacecraft. The work on these models has been reported at previous LDEF conferences. Since publication of these reports, a revision has been made to the AO calculation for LDEF, and further work has been done on the microenvironments model for solar exposure.

  9. Satellite Spacecraft Charging Control Materials.

    Science.gov (United States)

    1980-04-01

    MAAG, private comunication (3) A. PAILLOUS, Mise au point de matdriaux combinant la qualitf de rdflecteurs solaires et une bonne conductibilit...AD-A087 675 OFFICE NATIONAL D’EUDES ET DE RECHERCHES AEROSPATIALE--ETC F/G 22/2 SATELLITE SPACECRAFT CHARGING CONTROL MATERIALS*(U) APR 80 8 BENAISSA...this problem of outgassing (6)* The composite is obtained by lamin- ating at 280 C the quartz fabric with a FEP film and an aluminum (6) A.E. EAGLES et

  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. Spacecraft reliability/maintainability optimization.

    Science.gov (United States)

    Sharmahd, J. N.

    1972-01-01

    Description of a procedure to develop a methodology to optimize man-serviced systems for reliability and maintainability. The spacecraft systems are analyzed using failure modes and effects analysis and maintenance analysis, component mean-time-between failure, duty cycle, type of redundancy, and cost information to develop parametric data on various time intervals. Included are crew time-to-repair, cost, weight, and volume effects of increasing subsystem reliability above the baseline. Results are presented for space systems using the existing data from a research and applications module. These results show the minimum cost of sustaining mission operations.

  12. Method and System for Gamma-Ray Localization Induced Spacecraft Navigation Using Celestial Gamma-Ray Sources

    Science.gov (United States)

    Sheikh, Suneel I. (Inventor); Hisamoto, Chuck (Inventor); Arzoumanian, Zaven (Inventor)

    2015-01-01

    A method and system for spacecraft navigation using distant celestial gamma-ray bursts which offer detectable, bright, high-energy events that provide well-defined characteristics conducive to accurate time-alignment among spatially separated spacecraft. Utilizing assemblages of photons from distant gamma-ray bursts, relative range between two spacecraft can be accurately computed along the direction to each burst's source based upon the difference in arrival time of the burst emission at each spacecraft's location. Correlation methods used to time-align the high-energy burst profiles are provided. The spacecraft navigation may be carried out autonomously or in a central control mode of operation.

  13. Electrolysis Propulsion for Spacecraft Applications

    Science.gov (United States)

    deGroot, Wim A.; Arrington, Lynn A.; McElroy, James F.; Mitlitsky, Fred; Weisberg, Andrew H.; Carter, Preston H., II; Myers, Blake; Reed, Brian D.

    1997-01-01

    Electrolysis propulsion has been recognized over the last several decades as a viable option to meet many satellite and spacecraft propulsion requirements. This technology, however, was never used for in-space missions. In the same time frame, water based fuel cells have flown in a number of missions. These systems have many components similar to electrolysis propulsion systems. Recent advances in component technology include: lightweight tankage, water vapor feed electrolysis, fuel cell technology, and thrust chamber materials for propulsion. Taken together, these developments make propulsion and/or power using electrolysis/fuel cell technology very attractive as separate or integrated systems. A water electrolysis propulsion testbed was constructed and tested in a joint NASA/Hamilton Standard/Lawrence Livermore National Laboratories program to demonstrate these technology developments for propulsion. The results from these testbed experiments using a I-N thruster are presented. A concept to integrate a propulsion system and a fuel cell system into a unitized spacecraft propulsion and power system is outlined.

  14. Hybrid spacecraft attitude control system

    Directory of Open Access Journals (Sweden)

    Renuganth Varatharajoo

    2016-02-01

    Full Text Available The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.

  15. Estimating Torque Imparted on Spacecraft Using Telemetry

    Science.gov (United States)

    Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.

    2013-01-01

    There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.

  16. Computer simulation of spacecraft/environment interaction

    CERN Document Server

    Krupnikov, K K; Mileev, V N; Novikov, L S; Sinolits, V V

    1999-01-01

    This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.

  17. Neptune aerocapture mission and spacecraft design overview

    Science.gov (United States)

    Bailey, Robert W.; Hall, Jeff L.; Spliker, Tom R.; O'Kongo, Nora

    2004-01-01

    A detailed Neptune aerocapture systems analysis and spacecraft design study was performed as part of NASA's In-Space Propulsion Program. The primary objectives were to assess the feasibility of a spacecraft point design for a Neptune/Triton science mission. That uses aerocapture as the Neptune orbit insertion mechanism. This paper provides an overview of the science, mission and spacecraft design resulting from that study.

  18. Attitude Fusion Techniques for Spacecraft

    DEFF Research Database (Denmark)

    Bjarnø, Jonas Bækby

    areas such as highly miniaturized analog and digital electronics, instrument space qualification, test and validation procedures, sensor fusion techniques and optimized software implementations to reach a successful conclusion. The content of the project thus represents cutting edge aerospace technology...... due to the extreme performance that must be ascertained on all fronts whilst harnessing only a minimum of resources. Considering the physical limitations imposed by the μASC instrument as well as the next generation of smaller and more agile satellites, the main design drivers of the IRU......Spacecraft platform instability constitutes one of the most significant limiting factors in hyperacuity pointing and tracking applications, yet the demand for accurate, timely and reliable attitude information is ever increasing. The PhD research project described within this dissertation has...

  19. Rosetta spacecraft meets asteroid Steins

    Science.gov (United States)

    2008-08-01

    Steins is Rosetta’s first nominal scientific target. The spacecraft will rendezvous with the asteroid in the course of its first incursion into the asteroid belt located between the orbits of Mars and Jupiter, while on its way to comet 67/P Churyumov-Gerasimenko. The study of asteroids is extremely important as they represent a sample of Solar System material at different stages of evolution - key to understanding the origin of our own planet and of our planetary neighbourhood. The closest approach to Steins is due to take place on 5 September at 20:58 CEST (Central European Summer Time), from a distance of 800 km, during which the spacecraft will not be communicating with Earth. First ground contact with the spacecraft and announcement of successful fly-by will take place at 22:23 CEST. The first data and images collected by Rosetta will be sent to Earth throughout the night of 5 to 6 September and will undergo preliminary processing in the morning of 6 September. The first images will be made available for broadcasters via a special satellite feed on Saturday 6 September (details will be given on http://television.esa.int). To register for the events, please use the attached form. The press conference on 6 September will also be streamed on the ESA web: at http://www.esa.int/rosetta. Rosetta Steins Fly-By Doors open to the media 5 September 2008, 18:00, Building K ESA-ESOC Robert-Bosch Strasse 5, 64293 Darmstadt, Germany 18:00 - Doors open 18:00 - 19:00 Interview opportunities 19:00 - 20:15 Buffet dinner 20:15 - 20:30 The Steins Fly-By, Introduction by Paolo Ferri, Head of Solar and Planetary Missions Division (Mission Operations Dept.), ESA The crucial role of Flight Dynamics, by Trevor Morley, Rosetta Flight Dynamics Team, ESA 20:30 - 21:00 Live from Rosetta’s control room (loss of telemetry signal at 20:47) 22:23 - First telemetry on ground: signal of successful fly-by 23:00 - End of event Rosetta Steins Fly-By Press Conference 6 September 2008, 12

  20. Spacecraft sails through comet's tail

    Science.gov (United States)

    Katzoff, Judith A.

    Comet Giacobini-Zinner may not have a conventional bow shock, but the “interaction region” where the comet's sheath collides with the solar wind is a far more turbulent plasma than had been anticipated. On September 13, 2 days after the International Cometary Explorer (ICE) became the first spacecraft ever to pass through a comet's tail (Eos, September 3, 1985, p. 625), mission scientists gathered at the National Aeronautics and Space Administration's Goddard Space Flight Center (GSFC) to review their preliminary results. One scientist attending the news conference said he understood the interaction region to be “the most turbulent region that we have seen in the solar system to date.”

  1. The Dual Role of Calcium as Messenger and Stressor in Cell Damage, Death, and Survival

    Directory of Open Access Journals (Sweden)

    Claudia Cerella

    2010-01-01

    Full Text Available Ca2+ is an important second messenger participating in many cellular activities; when physicochemical insults deregulate its delicate homeostasis, it acts as an intrinsic stressor, producing/increasing cell damage. Damage elicits both repair and death responses; intriguingly, in those responses Ca2+ also participates as second messenger. This delineates a dual role for Ca2+ in cell stress, making difficult to separate the different and multiple mechanisms required for Ca2+-mediated control of cell survival and apoptosis. Here we attempt to disentangle the two scenarios, examining on the one side, the events implicated in deregulated Ca2+ toxicity and the mechanisms through which this elicits reparative or death pathways; on the other, reviewing the role of Ca2+ as a messenger in the transduction of these same signaling events.

  2. The effect of addiction to mobile messenger software and mental health among physical education students

    Directory of Open Access Journals (Sweden)

    Mostafa Bagherianfar

    2017-08-01

    Full Text Available Introduction: The objective of the present study is to the effect of addiction to mobile messenger software on mental health among physical education university students of Torbat-e-Heydarieh city.  Materials and Methods: The statistical population of this descriptive-correlational study included all physical education university students of Torbat-e-Heydarieh city. 169 students out of 302 were chosen as the sample of study, for which stratified sampling method was applied. In order to collect data, Goldberg general health questionnaire and addiction to mobile messenger software inventory were used. Data were analyzed using descriptive and illative statistics.  Results: The research findings showed that there is a statistically significant relationship between addiction to mobile messenger software's and mental health among the students of physical education (P

  3. Kindling and second messengers: an approach to the neurobiology of recurrence in bipolar disorder.

    Science.gov (United States)

    Ghaemi, S N; Boiman, E E; Goodwin, F K

    1999-01-15

    Since bipolar disorder is inherently a longitudinal illness characterized by recurrence and cycling of mood episodes, neurobiological theories involving kindlinglike phenomena appear to possess a certain explanatory power. An approach to understanding kindlinglike phenomena at the molecular level has been made possible by advances in research on second-messenger systems in the brain. The time frame of interest has shifted from the microseconds of presynaptic events to hours, days, months, and even years in the longer duration of events beyond the synapse--through second messengers, gene regulation, and synthesis of long-acting trophic factors. These complex interlocking systems may explain how environmental stress could interact over time with genetic vulnerability to produce illness. In its two sections, this paper will review an approach to understanding two major aspects of the neurobiology of bipolar disorder: kindling phenomena and second-messenger mechanisms. We will suggest that these two fields of research together help explain the biology of recurrence.

  4. Volcanism on Mercury: Evidence from the first MESSENGER flyby for extrusive and explosive activity and the volcanic origin of plains

    Science.gov (United States)

    Head, James W.; Murchie, Scott L.; Prockter, Louise M.; Solomon, Sean C.; Chapman, Clark R.; Strom, Robert G.; Watters, Thomas R.; Blewett, David T.; Gillis-Davis, Jeffrey J.; Fassett, Caleb I.; Dickson, James L.; Morgan, Gareth A.; Kerber, Laura

    2009-08-01

    The first MESSENGER flyby of Mercury obtained images of 21% of the surface not seen by Mariner 10, including the center and western half of the Caloris basin and regions near the terminator that show details of the nature of smooth and intercrater plains. These new data have helped to address and resolve a series of longstanding questions on the existence and nature of volcanism on Mercury and the distribution of volcanic materials. Data from the Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft have shown the following: (1) Numerous volcanic vents, in the form of irregularly shaped rimless depressions, are concentrated around the interior edge of the Caloris basin. (2) These vents appear to be sources for effusive volcanism that in one case built a shield in excess of 100 km in diameter and in some cases formed bright haloes around the vents that are interpreted to represent pyroclastic eruptions. (3) Lobate margins of plains units, seen previously in Mariner 10 data, are documented in MESSENGER images with more clarity and are often distinctive in morphology and color properties, supporting the interpretation that these features are the edges of lava flow units. (4) The interior of the Caloris basin is filled with plains units spectrally distinctive from the rim deposits, and comparison with the lunar Imbrium basin and superposed impact crater stratigraphy provide evidence that these units are volcanic in origin; detailed differences in the mineralogy of lava flow units, so prominent in Imbrium, are not seen in the Caloris interior. (5) Some of the smooth plains surrounding the exterior of the Caloris basin show distinct differences in color and morphological properties, supporting a volcanic origin. (6) Some smooth and intercrater plains units distant from the Caloris basin show evidence of flooding and embayment relations unrelated to Caloris ejecta emplacement; local and regional geological and color relationships support a volcanic origin for

  5. Mercury's Exosphere During MESSENGER's Second Flyby: Detection of Magnesium and Distinct Distributions of Neutral Species

    Science.gov (United States)

    McClintock, William E.; Vervack, Ronald J., Jr.; Bradley, E. Todd; Killen, Rosemary M.; Mouawad, Nelly; Sprague, Ann L.; Burger, Matthew H.; Solomon, Sean C.; Izenberg, Noam R.

    2009-01-01

    During MESSENGER's second Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer observed emission from Mercury's neutral exosphere. These observations include the first detection of emission from magnesium. Differing spatial distributions for sodium, calcium, and magnesium were revealed by observations beginning in Mercury's tail region, approximately 8 Mercury radii anti-sunward of the planet, continuing past the nightside, and ending near the dawn terminator. Analysis of these observations, supplemented by observations during the first Mercury flyby as well as those by other MESSENGER instruments, suggests that the distinct spatial distributions arise from a combination of differences in source, transfer, and loss processes.

  6. Astronomy's New Messengers: A traveling exhibit on gravitational-wave physics

    Science.gov (United States)

    Cavaglià, Marco; Hendry, Martin; Márka, Szabolcs; Reitze, David H.; Riles, Keith

    2010-01-01

    The Laser Interferometer Gravitational-wave Observatory exhibit Astronomy's New Messengers: Listening to the Universe with Gravitational Waves is traveling to colleges, universities, museums and other public institutions throughout the United States. Astronomy's New Messengers primarily communicates with an adolescent and young adult audience, potentially inspiring them into the field of science. Acknowledging that this audience is traditionally a difficult one to attract, the exhibit publicly announces itself in a charismatic fashion to reach its principal goals of broadening the community of people interested in science and encouraging interest in science among young people.

  7. Anomalous accelerations in spacecraft flybys of the Earth

    Science.gov (United States)

    Acedo, L.

    2017-12-01

    The flyby anomaly is a persistent riddle in astrodynamics. Orbital analysis in several flybys of the Earth since the Galileo spacecraft flyby of the Earth in 1990 have shown that the asymptotic post-encounter velocity exhibits a difference with the initial velocity that cannot be attributed to conventional effects. To elucidate its origin, we have developed an orbital program for analyzing the trajectory of the spacecraft in the vicinity of the perigee, including both the Sun and the Moon's tidal perturbations and the geopotential zonal, tesseral and sectorial harmonics provided by the EGM96 model. The magnitude and direction of the anomalous acceleration acting upon the spacecraft can be estimated from the orbital determination program by comparing with the trajectories fitted to telemetry data as provided by the mission teams. This acceleration amounts to a fraction of a mm/s2 and decays very fast with altitude. The possibility of some new physics of gravity in the altitude range for spacecraft flybys is discussed.

  8. TTEthernet for Integrated Spacecraft Networks

    Science.gov (United States)

    Loveless, Andrew

    2015-01-01

    Aerospace projects have traditionally employed federated avionics architectures, in which each computer system is designed to perform one specific function (e.g. navigation). There are obvious downsides to this approach, including excessive weight (from so much computing hardware), and inefficient processor utilization (since modern processors are capable of performing multiple tasks). There has therefore been a push for integrated modular avionics (IMA), in which common computing platforms can be leveraged for different purposes. This consolidation of multiple vehicle functions to shared computing platforms can significantly reduce spacecraft cost, weight, and design complexity. However, the application of IMA principles introduces significant challenges, as the data network must accommodate traffic of mixed criticality and performance levels - potentially all related to the same shared computer hardware. Because individual network technologies are rarely so competent, the development of truly integrated network architectures often proves unreasonable. Several different types of networks are utilized - each suited to support a specific vehicle function. Critical functions are typically driven by precise timing loops, requiring networks with strict guarantees regarding message latency (i.e. determinism) and fault-tolerance. Alternatively, non-critical systems generally employ data networks prioritizing flexibility and high performance over reliable operation. Switched Ethernet has seen widespread success filling this role in terrestrial applications. Its high speed, flexibility, and the availability of inexpensive commercial off-the-shelf (COTS) components make it desirable for inclusion in spacecraft platforms. Basic Ethernet configurations have been incorporated into several preexisting aerospace projects, including both the Space Shuttle and International Space Station (ISS). However, classical switched Ethernet cannot provide the high level of network

  9. Tethered spacecraft in asteroid gravitational environment

    Science.gov (United States)

    Burov, Alexander A.; Guerman, Anna D.; Kosenko, Ivan I.; Nikonov, Vasily I.

    2018-02-01

    Relative equilibria of a pendulum attached to the surface of a uniformly rotating celestial body are considered. The locations of the tether anchor that correspond to a given spacecraft position are defined. The domains, where the spacecraft can be held with the help of such a pendulum, are also described. Stability of the found relative equilibria is studied.

  10. Spacecraft command and control using expert systems

    Science.gov (United States)

    Norcross, Scott; Grieser, William H.

    1994-11-01

    This paper describes a product called the Intelligent Mission Toolkit (IMT), which was created to meet the changing demands of the spacecraft command and control market. IMT is a command and control system built upon an expert system. Its primary functions are to send commands to the spacecraft and process telemetry data received from the spacecraft. It also controls the ground equipment used to support the system, such as encryption gear, and telemetry front-end equipment. Add-on modules allow IMT to control antennas and antenna interface equipment. The design philosophy for IMT is to utilize available commercial products wherever possible. IMT utilizes Gensym's G2 Real-time Expert System as the core of the system. G2 is responsible for overall system control, spacecraft commanding control, and spacecraft telemetry analysis and display. Other commercial products incorporated into IMT include the SYBASE relational database management system and Loral Test and Integration Systems' System 500 for telemetry front-end processing.

  11. La escritura simbólica y el lenguaje escrito en los usuarios del Messenger The Symbols and Written Language of Users of Messenger

    Directory of Open Access Journals (Sweden)

    Verónica García Martínez

    2010-03-01

    Full Text Available El presente estudio es el resultado de un trabajo de tesis de comunicación en el que se aborda el tema de la utilización del lenguaje en el Messenger y sus posibles repercusiones en los manuscritos de los estudiantes de nivel medio superior. Es un estudio desarrollado entre adolescentes usuarios del Messenger, que utilizan la gama de símbolos y signos que les proporciona esta herramienta, para sustituir la escritura que comúnmente se usa en los manuscritos. La metodología es del enfoque cualitativo y se trata de un estudio comparativo basado en el modelo de comunicación referencial. El trabajo empírico se realizó entre un total de 16 jóvenes de dos escuelas diferentes de nivel medio superior, cuya edad está entre los 15 y 17 años, los cuales a su vez se integraron en dos grupos de ocho sujetos para el estudio en una primera etapa y otros ocho en una segunda. Básicamente se diferenciaron los que utilizan con mucha frecuencia el Messenger y los que lo utilizan muy poco, o no lo utilizan. Las técnicas de recolección de datos fueron: observación durante sesiones de chat, escritos a máquina (ordenador y manuscritos. La técnica para la interpretación de los datos fue de análisis de contenido. Los resultados sugieren que existe escasa relación entre la utilización de signos y símbolos en el Messenger y la calidad en la redacción de los textos, particularmente en los manuscritos.This work presents the results of a postgraduate thesis on communication, particularly the use of language. Messenger is one of the most popular ways for communicating by signs and symbols. This study was carried out on junior high school students in state education. This research explores the possible impact on junior high school students’ written work due to their use of Messenger. To address this question, the referential communication model with the qualitative approach was used in order to carry out a comparative study. Data were gathered from 16

  12. Mercury: a prediction for bulk chemical composition and internal structure in readiness for new MESSENGER data

    Science.gov (United States)

    Prentice, A. J.

    2008-12-01

    The MESSENGER spacecraft has confirmed that Mercury's magnetic field is dominantly dipolar and due to an active dynamo in a molten outer core (Solomon et al, 2008 Science 321 59). An energy source is needed to maintain this dynamo. Either liquid iron is freezing at the surface of an inner solid core (as proposed here) or solid iron is precipitating within an outer sulphur-rich core (Chen et al, 2008 GRL 35 L07201). If the outer core does not contain sulphur and consists solely of pure metal (Fe, Ni, Cr,..), then an active dynamo is inconsistent with previous numerical models for the radiogenic thermal evolution of the planet. Those earlier models found that the present temperature at the core/mantle boundary (CMB) is ~ 500 K below the melting temperature of metal ~ 2030 K for a CMB pressure of 70 kbar. The earlier calculations were based on low lunar abundances of U and Th. Here I present a new model for the bulk chemical composition, thermal evolution and current internal structure of Mercury. The model is based on the modern Laplacian theory of solar system origin (Prentice, 1978 Moon Planets 19 341; 2001 Earth Moon & Planets 87 11; 2006 Publ. Astron. Soc. Aust. (PASA) 23 1; 2008 - URL below). A key feature of this theory is that the planets formed from a concentric system of gas rings (n = 0, 1, 2,..) that were shed by the contracting protosolar cloud. The temperatures Tn of the rings scale with mean orbital radius Rn closely as Tn ~ Rn-0.9. Mercury plays a crucial role in calibrating this relationship because of a condensation process of metal/silicate fractionation (Lewis, 1972 EPSL 15 286). Choosing Tn ~ 1630 K for mean orbit gas ring pressure of 0.17 bar, the condensate consists mostly of Fe-Ni-Cr (mass fraction 0.671), gehlenite (0.190) and Mg-silicates (0.081). It has mean density 5.30 g/cm3. Na, K and S are absent. The mass fractions of U and Th, namely 5.66 × 10-8 & 2.08 × 10-7, are a factor of 4.3 times greater than those of the proto-Earth condensate

  13. Global Inventory and Characterization of Pyroclastic Deposits on Mercury: New Insights into Pyroclastic Activity from MESSENGER Orbital Data

    Science.gov (United States)

    Goudge, Timothy A.; Head, James W.; Kerber, Laura; Blewett, David T.; Denevi, Brett W.; Domingue, Deborah L.; Gillis-Davis, Jeffrey J.; Gwinner, Klaus; Helbert, Joern; Holsclaw, Gregory M.; hide

    2014-01-01

    We present new observations of pyroclastic deposits on the surface of Mercury from data acquired during the orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. The global analysis of pyroclastic deposits brings the total number of such identified features from 40 to 51. Some 90% of pyroclastic deposits are found within impact craters. The locations of most pyroclastic deposits appear to be unrelated to regional smooth plains deposits, except some deposits cluster around the margins of smooth plains, similar to the relation between many lunar pyroclastic deposits and lunar maria. A survey of the degradation state of the impact craters that host pyroclastic deposits suggests that pyroclastic activity occurred on Mercury over a prolonged interval. Measurements of surface reflectance by MESSENGER indicate that the pyroclastic deposits are spectrally distinct from their surrounding terrain, with higher reflectance values, redder (i.e., steeper) spectral slopes, and a downturn at wavelengths shorter than approximately 400nm (i.e., in the near-ultraviolet region of the spectrum). Three possible causes for these distinctive characteristics include differences in transition metal content, physical properties (e.g., grain size), or degree of space weathering from average surface material on Mercury. The strength of the near-ultraviolet downturn varies among spectra of pyroclastic deposits and is correlated with reflectance at visible wavelengths. We suggest that this interdeposit variability in reflectance spectra is the result of either variable amounts of mixing of the pyroclastic deposits with underlying material or inherent differences in chemical and physical properties among pyroclastic deposits.

  14. Effects of Induction and Magnetopause Reconnection on Mercury's Magnetosphere: MESSENGER Observations and Global MHD Simulations with Coupled Planetary Interior

    Science.gov (United States)

    Jia, X.; Slavin, J. A.; Poh, G.; Toth, G.; Gombosi, T. I.

    2016-12-01

    It has long been suggested that two processes, i.e., erosion of the dayside magnetosphere due to strong magnetopause reconnection and the shielding effect of the induction currents at the planetary core, compete against each other in governing the structure of Mercury's magnetosphere. We have combined analysis of MESSENGER data during extreme solar wind conditions with global MHD simulations to assess the relative importance of the two processes. Following the study of Slavin et al. (2014), we have analyzed an additional set of MESSENGER magnetopause crossings to determine the dependence of the magnetopause standoff distance on solar wind parameters. We have also employed the global MHD model of Jia et al. (2015) that electromagnetically couples Mercury's interior to the surrounding space environment to simulate the response of the system to solar wind forcing for a wide range of solar wind and IMF conditions. We find that while the magnetopause standoff distance decreases with increasing solar wind pressure, just as expected, its dependence on the external pressure follows closely a power-law relationship with an index of -1/6, rather than a steeper power-law falling-off expected for the case with only induction present. Our results suggest that for the external conditions examined, induction and magnetopause reconnection appear to play equally important roles in determining the global configuration of Mercury's magnetosphere, consistent with the finding obtained by Slavin et al. (2014). We also find that the magnetospheric current systems produce magnetic perturbations that are spatially non-uniform in nature, resulting in induced magnetic field at the core that contains significant power in both the dipole and high order moments. Based on the simulation results, we determine how the induced field varies with the solar wind conditions, and provide quantitative constraints on the ability of Mercury's core to shield the planetary surface from direct solar wind

  15. In-situ radio-metric tracking to support navigation for interplanetary missions with multiple spacecraft

    Science.gov (United States)

    Kahn, Robert D.; Thurman, Sam W.; Edwards, Charles D.

    1993-01-01

    Doppler and ranging measurements between spacecraft can be obtained only when the ratio of the total received signal power to noise power density (P(sub t/N(sub 0)) at the receiving spacecraft is sufficiently large that reliable signal detection can be achieved within a reasonable time period. In this paper, the requirements on P(sub t)/N(sub 0) for reliable carrier signal detection is calculated as a function of various system parameters, including characteristics of the spacecraft computing hardware and a priori uncertainty in spacecraft-spacecraft relative velocity and acceleration. Also calculated is the P(sub t)/N(sub 0) requirement for relaible detection of a ranging signal, consistting of a carrier with pseudo-noise phase modulation. Once the P(sub t)/N(sub 0) requirement is determined, then for a given set of assumed spacecraft telecommunication characteristics (transmitted signal power, antenna gains, receiver noise temperatures) it is possible to calculate the maximum range at which a carrier signal or ranging signal may be acquired. A brief error covariance analysis has been conducted to illustrate the utility of in situ Doppler and ranging measurements for Mars approach navigation. The results indicate that navigation accuracies of a few kilometers can be achieved with either data type. The analysis also illustrates dependency of the achievable accuracy on the approach trajectory velocity.

  16. Social and Virtual Networks: Evaluating Synchronous Online Interviewing Using Instant Messenger

    Science.gov (United States)

    Hinchcliffe, Vanessa; Gavin, Helen

    2009-01-01

    This paper describes an evaluation of the quality and utility of synchronous online interviewing for data collection in social network research. Synchronous online interviews facilitated by Instant Messenger as the communication medium, were undertaken with ten final year university students. Quantitative and qualitative content analysis of…

  17. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Learners, apprentices, messengers, students, or handicapped... handicapped workers employed under special certificates as provided in section 14 of the Act. (a) With respect... education, or handicapped workers employed at special minimum hourly rates under Special Certificates...

  18. Observations of Mercury’s Neutral Hydrogen Exosphere During the MESSENGER Orbital Phase

    Science.gov (United States)

    Vervack, Ronald J.; Hurley, Dana; Pryor, Wayne R.

    2017-10-01

    Because of the difficulty of observing H Lyman α at Mercury remotely, the MESSENGER mission afforded the first chance since the Mariner 10 flybys to investigate the neutral hydrogen exosphere of Mercury in detail. Mariner 10 discovered H at Mercury, but left many questions about the puzzling temperature and density distributions unanswered. Sparse observations during the MESSENGER flybys of Mercury suggested that the H exosphere was grossly similar to what was observed by Mariner 10, but with higher overall emission levels, and they provided no answers to the outstanding issues from Mariner 10. Observations of H Lyman α emission by the Ultraviolet and Visible Spectrometer (UVVS) component of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) instrument onboard MESSENGER were conducted regularly throughout the MESSENGER orbital phase. These observations provide a much more complete picture of the H exosphere at Mercury. We present an analysis of the UVVS orbital observations, focusing on the temporal and spatial distribution of the hydrogen about the planet. Preliminary models will be shown, and the UVVS data will be compared and contrasted to the Mariner 10 data to address the long-outstanding questions about this element of Mercury’s complex exosphere. Support from the NASA Discovery Data Analysis Program is gratefully acknowledged.

  19. Comparing Strategies for Health Information Dissemination: Messengers That Can Help or Hinder.

    Science.gov (United States)

    Fishman, Jessica; Greenberg, Patricia; Bagga, Margy Barbieri; Casarett, David; Propert, Kathleen

    2017-01-01

    To test the effects of different messengers on the dissemination of health information. An experimental study exposed participants to 12 news articles pertaining to 1 of 3 health topics framed from the perspective of 4 generic messengers: religious figures, doctors, celebrity patients, or ordinary patients. Participants select as many of the 12 articles as desired. A cancer clinic within a large, urban hospital serving a sociodemographically diverse patient population. Eighty-nine patients with a history of cancer. The primary outcome was the frequency with which each news story was selected. Summary statistics and a general estimating equation model. For each health topic, news articles using celebrity messengers were the least likely to be selected; almost half of the participants (36 [41.4%] of 87) rejected all such articles. Articles linked to religious figures were equally unpopular ( P = .59). Articles that used doctors or ordinary patients as the messenger were very likely to be selected: Nearly all women (84 [96.6%] of 87) selected at least one of these. Furthermore, the odds of choosing articles linked to celebrities or religious leaders were statistically significantly lower than the odds of choosing those linked to ordinary patients or doctors ( P celebrities or religious figures were consistently less likely to be selected than those linked to ordinary patients, or doctors.

  20. A Contemporary, Laboratory-Intensive Course on Messenger RNA Transcription and Processing

    Science.gov (United States)

    Carson, Sue; Miller, Heather

    2012-01-01

    Messenger ribonucleic acid (mRNA) plays a pivotal role in the central dogma of molecular biology. Importantly, molecular events occurring during and after mRNA synthesis have the potential to create multiple proteins from one gene, leading to some of the remarkable protein diversity that genomes hold. The North Carolina State University…

  1. Unit Messengers, First Trial Materials, Inspection Set, [Australian Science Education Project].

    Science.gov (United States)

    Australian Council for Educational Research, Hawthorn.

    The Australian Science Education Project is producing material designed for use in grades 7-10 of Australian schools. This is the first trial version of a unit concerned with sight, hearing, touch, taste, and smell. The teacher's guide outlines the use of the two booklets ("Messengers" and "Use of the Senses") intended for all…

  2. Single-cell messenger RNA sequencing reveals rare intestinal cell types

    NARCIS (Netherlands)

    Grün, Dominic; Lyubimova, Anna; Kester, Lennart; Wiebrands, Kay; Basak, Onur; Sasaki, Nobuo; Clevers, Hans; van Oudenaarden, Alexander

    2015-01-01

    Understanding the development and function of an organ requires the characterization of all of its cell types. Traditional methods for visualizing and isolating subpopulations of cells are based on messenger RNA or protein expression of only a few known marker genes. The unequivocal identification

  3. Shooting the Messenger: Mediating the Public and the Role of the ...

    African Journals Online (AJOL)

    Shooting the Messenger: Mediating the Public and the Role of the Media in South Africa's Xenophobic Violence. ... at: there has been a communications breakdown in South Africa at a local level between communities and the state, as well as within communities, which lies at the root of much of the anger and violence.

  4. Farm Women, Solidarity, and "The Suffrage Messenger": Nebraska Suffrage Activism on the Plains, 1915-1917

    Science.gov (United States)

    Heider, Carmen

    2012-01-01

    In 1914 Nebraska men once again voted against the amendment that would have granted full suffrage to Nebraska women. This article focuses on the three years immediately after that defeat. It explores the remaining seventeen issues of the "Suffrage Messenger" and asks the following question: how did the suffrage newspaper portray and…

  5. Mobile Immersion: An Experiment Using Mobile Instant Messenger to Support Second-Language Learning

    Science.gov (United States)

    Lai, Arthur

    2016-01-01

    Immersion has been an acclaimed approach for second-language acquisition, but is not available to most students. The idea of this study was to create a mobile immersion environment on a smartphone using a mobile instant messenger, WhatsApp™. Forty-five Form-1 (7th grade) students divided into the Mobile Group and Control Group participated in a…

  6. Multi-messenger Observations of a Binary Neutron Star Merger

    DEFF Research Database (Denmark)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.

    2017-01-01

    ) with a time delay of with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2...

  7. Low power arcjet system spacecraft impacts

    Science.gov (United States)

    Pencil, Eric J.; Sarmiento, Charles J.; Lichtin, D. A.; Palchefsky, J. W.; Bogorad, A. L.

    1993-01-01

    Application of electrothermal arcjets on communications satellites requires assessment of integration concerns identified by the user community. Perceived risks include plume contamination of spacecraft materials, induced arcing or electrostatic discharges between differentially charged spacecraft surfaces, and conducted and radiated electromagnetic interference (EMI) for both steady state and transient conditions. A Space Act agreement between Martin Marietta Astro Space, the Rocket Research Company, and NASA's Lewis Research Center was established to experimentally examine these issues. Spacecraft materials were exposed to an arcjet plume for 40 hours, representing 40 weeks of actual spacecraft life, and contamination was characterized by changes in surface properties. With the exception of the change in emittance of one sample, all measurable changes in surface properties resulted in acceptable end of life characteristics. Charged spacecraft samples were benignly and consistently reduced to ground potential during exposure to the powered arcjet plume, suggesting that the arcjet could act as a charge control device on spacecraft. Steady state EMI signatures obtained using two different power processing units were similar to emissions measured in a previous test. Emissions measured in UHF, S, C, Ku and Ka bands obtained a null result which verified previous work in the UHF, S, and C bands. Characteristics of conducted and radiated transient emissions appear within standard spacecraft susceptibility criteria.

  8. Correcting Spacecraft Jitter in Hirise Images

    Science.gov (United States)

    Sutton, S. S.; Boyd, A. K.; Kirk, R. L.; Cook, D.; Backer, J. W.; Fennema, A.; Heyd, R.; McEwen, A. S.; Mirchandani, S. D.

    2017-07-01

    Mechanical oscillations or vibrations on spacecraft, also called pointing jitter, cause geometric distortions and/or smear in high resolution digital images acquired from orbit. Geometric distortion is especially a problem with pushbroom type sensors, such as the High Resolution Imaging Science Experiment (HiRISE) instrument on board the Mars Reconnaissance Orbiter (MRO). Geometric distortions occur at a range of frequencies that may not be obvious in the image products, but can cause problems with stereo image correlation in the production of digital elevation models, and in measuring surface changes over time in orthorectified images. The HiRISE focal plane comprises a staggered array of fourteen charge-coupled devices (CCDs) with pixel IFOV of 1 microradian. The high spatial resolution of HiRISE makes it both sensitive to, and an excellent recorder of jitter. We present an algorithm using Fourier analysis to resolve the jitter function for a HiRISE image that is then used to update instrument pointing information to remove geometric distortions from the image. Implementation of the jitter analysis and image correction is performed on selected HiRISE images. Resulting corrected images and updated pointing information are made available to the public. Results show marked reduction of geometric distortions. This work has applications to similar cameras operating now, and to the design of future instruments (such as the Europa Imaging System).

  9. CORRECTING SPACECRAFT JITTER IN HIRISE IMAGES

    Directory of Open Access Journals (Sweden)

    S. S. Sutton

    2017-07-01

    Full Text Available Mechanical oscillations or vibrations on spacecraft, also called pointing jitter, cause geometric distortions and/or smear in high resolution digital images acquired from orbit. Geometric distortion is especially a problem with pushbroom type sensors, such as the High Resolution Imaging Science Experiment (HiRISE instrument on board the Mars Reconnaissance Orbiter (MRO. Geometric distortions occur at a range of frequencies that may not be obvious in the image products, but can cause problems with stereo image correlation in the production of digital elevation models, and in measuring surface changes over time in orthorectified images. The HiRISE focal plane comprises a staggered array of fourteen charge-coupled devices (CCDs with pixel IFOV of 1 microradian. The high spatial resolution of HiRISE makes it both sensitive to, and an excellent recorder of jitter. We present an algorithm using Fourier analysis to resolve the jitter function for a HiRISE image that is then used to update instrument pointing information to remove geometric distortions from the image. Implementation of the jitter analysis and image correction is performed on selected HiRISE images. Resulting corrected images and updated pointing information are made available to the public. Results show marked reduction of geometric distortions. This work has applications to similar cameras operating now, and to the design of future instruments (such as the Europa Imaging System.

  10. Foot Pedals for Spacecraft Manual Control

    Science.gov (United States)

    Love, Stanley G.; Morin, Lee M.; McCabe, Mary

    2010-01-01

    Fifty years ago, NASA decided that the cockpit controls in spacecraft should be like the ones in airplanes. But controls based on the stick and rudder may not be best way to manually control a vehicle in space. A different method is based on submersible vehicles controlled with foot pedals. A new pilot can learn the sub's control scheme in minutes and drive it hands-free. We are building a pair of foot pedals for spacecraft control, and will test them in a spacecraft flight simulator.

  11. Spacecraft exploration of Phobos and Deimos

    OpenAIRE

    Duxbury, Thomas C.; Zakharov, Alexander V.; Hoffmann, Harald; Edward A. Guinness

    2014-01-01

    We review the previous exploration of Phobos and Deimos by spacecraft. The first close-up images of Phobos and Deimos were obtained by the Mariner 9 spacecraft in 1971, followed by much image data from the two Viking orbiters at the end of the 70s, which formed the basis for early Phobos and Deimos shape and dynamic models. The Soviet Phobos 2 spacecraft came within 100 km of landing on Phobos in 1988. Mars Global Surveyor (1996–2006) and Mars Reconnaissance Orbiter (since 2005) made close-up...

  12. Materials and processes for spacecraft and high reliability applications

    CERN Document Server

    D Dunn, Barrie

    2016-01-01

    The objective of this book is to assist scientists and engineers select the ideal material or manufacturing process for particular applications; these could cover a wide range of fields, from light-weight structures to electronic hardware. The book will help in problem solving as it also presents more than 100 case studies and failure investigations from the space sector that can, by analogy, be applied to other industries. Difficult-to-find material data is included for reference. The sciences of metallic (primarily) and organic materials presented throughout the book demonstrate how they can be applied as an integral part of spacecraft product assurance schemes, which involve quality, material and processes evaluations, and the selection of mechanical and component parts. In this successor edition, which has been revised and updated, engineering problems associated with critical spacecraft hardware and the space environment are highlighted by over 500 illustrations including micrographs and fractographs. Sp...

  13. Aneutronic Fusion Spacecraft Architecture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Description: provide framework to realize fusion propulsion for long-range space travel; analyze “hybrid” schemes with a solar or fission primary energy...

  14. Resolving Spacecraft Earth-Flyby Anomalies with Measured Light Speed Anisotropy

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2008-07-01

    Full Text Available Doppler shift observations of spacecraft, such as Galileo, NEAR, Cassini, Rosetta and MESSENGER in earth flybys, have all revealed unexplained speed “anomalies” — that the Doppler-shift determined speeds are inconsistent with expected speeds. Here it is shown that these speed anomalies are not real and are actually the result of using an incorrect relationship between the observed Doppler shift and the speed of the space- craft — a relationship based on the assumption that the speed of light is isotropic in all frames, viz invariant. Taking account of the repeatedly measured light-speed anisotropy the anomalies are resolved ab initio . The Pioneer 10 / 11 anomalies are discussed, but not resolved. The spacecraft observations demonstrate again that the speed of light is not invariant, and is isotropic only with respect to a dynamical 3-space. The existing Doppler shift data also offers a resource to characterise a new form of gravitational waves, the dynamical 3-space turbulence, that has also been detected by other tech- niques. The Einstein spacetime formalism uses a special definition of space and time coordinates that mandates light speed invariance for all observers, but which is easily misunderstood and misapplied.

  15. Passive Wireless Sensors for Spacecraft Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — New classes of sensors are needed on spacecraft that can be interrogated remotely using RF signals and respond with the sensor's identity as well as the...

  16. Space Robotics: What is a Robotic Spacecraft?

    Directory of Open Access Journals (Sweden)

    Alex Ellery

    2008-11-01

    Full Text Available In this first of three short papers, I introduce some of the basic concepts of space engineering with an emphasis on some specific challenging areas of research that are peculiar to the application of robotics to space development and exploration. The style of these short papers is pedagogical and this paper stresses the unique constraints that space application imposes. This first paper is thus a general introduction to the nature of spacecraft engineering and its application to robotic spacecraft. I consider the constraints and metrics used by spacecraft engineers in the design of spacecraft and how these constraints impose challenges to the roboticist. The following two papers consider specific robotics issues in more detail.

  17. A Sustainable Spacecraft Component Database Solution Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Numerous spacecraft component databases have been developed to support NASA, DoD, and contractor design centers and design tools. Despite the clear utility of...

  18. Odor Control in Spacecraft Waste Management Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft and lunar bases generate a variety of wastes containing water, including food wastes, feces, and brines. Disposal of these wastes, as well as recovery of...

  19. Fermi FT2 Spacecraft Pointing Files

    Data.gov (United States)

    National Aeronautics and Space Administration — This utility permits you to download the most current version of the spacecraft (FT2) file predicting the LAT's pointing for a given mission week. The FT2 file is a...

  20. Participation of women in spacecraft science teams

    Science.gov (United States)

    Rathbun, Julie

    2017-06-01

    There is an ongoing discussion about the participation of women in science and particularly astronomy. Demographic data from NASA's robotic planetary spacecraft missions show women scientists to be consistently under-represented.

  1. Computer failure caused loss of Mars spacecraft

    National Research Council Canada - National Science Library

    Zielinski, Sarah

    2007-01-01

    A computer error that occurred 5 months before NASA lost contact with the Mars Global Surveyor on 2 November 2006 led to the spacecraft's eventual battery failure and subsequent loss of orientation...

  2. Mirage Fire Sensor for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft fires create exception risks to crew members. There is usually no place to escape. Even small amounts of hardware damage can compromise a mission. The...

  3. Analisis dan Perancangan Aplikasi Bee-Messenger Sebagai Media-Media Instant Messanging di Universitas Bina Nusantara

    Directory of Open Access Journals (Sweden)

    Eddy Santosa Jaya

    2010-12-01

    Full Text Available Technology today has progressed at a rapid rate, as well as with instant messaging growing into all aspects of life, even more so in the advancement of communication technology. By using the VoIP feature, users can communicate by voice via the Internet. Messenger as a communication medium that is fast, accurate and low cost is expected to meet the need for a practical communication media. The purpose of this study is to analyze and design a messaging application called Bee-Messenger which will be used as a medium of instant messaging in Bina Nusantara University, and also analyze the needs of users with feature-contained in commonly used messenger applications. Research methods used are literature review, field studies, and field observations. Evaluation is based on the comparison of Bee-Messenger features with the same features found in Yahoo Messenger and MSN Messenger. Bee-Messenger can also activate YM and MSN messaging accounts simultaneously in a single application that gives users a practical application messaging. 

  4. Model of coupling discharges into spacecraft structures

    Science.gov (United States)

    Woods, A. J.; Treadway, M. J.; Grismore, R.; Leadon, R. E.; Flanagan, T.; Wenaas, E. P.

    1980-01-01

    The calculated results of a semiempirical model for electron-caused electromagnetic pulse (ECEMP) are compared to the experimental data for three spacecraft geometries. The appropriateness of certain model assumptions which have been employed in the absence of a microscopic theory for dielectric breakdown and associated electron blowoff is discussed. Results are limited to the exterior response of spacecraft structures, although neither the model nor the experiments were limited to the outside problem. Rationales for model assumptions are provided.

  5. Taurus Lightweight Manned Spacecraft Earth orbiting vehicle

    Science.gov (United States)

    Bosset, M.

    The Taurus Lightweight Manned Spacecraft (LMS) was developed by students of the University of Maryland's Aerospace Engineering course in Space Vehicle Design. That course required students to design an Alternative Manned Spacecraft (AMS) to augment or replace the Space Transportation System and meet the following design requirements: (1) launch on the Taurus Booster being developed by Orbital Sciences Corporation; (2) 99.9 percent assured crew survival rate; (3) technology cutoff date of 1 Jan. 1991; (4) compatibility with current space administration infrastructure; and (5) first flight by May 1995. The Taurus LMS design meets the above requirements and represents an initial step toward larger and more complex spacecraft. The Taurus LMS has a very limited application when compared to the space shuttle, but it demonstrates that the U.S. can have a safe, reliable, and low-cost space system. The Taurus LMS is a short mission duration spacecraft designed to place one man into low Earth orbit (LEO). The driving factor for this design was the low payload carrying capabilities of the Taurus Booster - 1300 kg to a 300-km orbit. The Taurus LMS design is divided into six major design sections. The Human Factors section deals with the problems of life support and spacecraft cooling. The Propulsion section contains the Abort System, the Orbital Maneuvering System (OMS), the Reaction Control System (RCS), and Power Generation. The thermal protection systems and spacecraft structure are contained in the Structures section. The Avionics section includes Navigation, Attitude Determination, Data Processing, Communication systems, and Sensors. The Mission Analysis section was responsible for ground processing and spacecraft astrodynamics. The Systems Integration Section pulled the above sections together into one spacecraft, and addressed costing and reliability.

  6. Underactuated Spacecraft Control with Disturbance Compensation

    Science.gov (United States)

    2015-08-31

    permission to manufacture, use, or sell any patented invention that may relate to them. This report is the result of contracted fundamental research...utilizes Solar Radiation Pressure (SRP) to restore linear controllability to a spacecraft with only two functional Reaction Wheels (RWs). The second...The failure of Reaction Wheels (RWs) in an array can impair the spacecraft’s ability to perform imaging missions, during which a prescribed inertial

  7. Standard user data services for spacecraft applications

    Science.gov (United States)

    Smith, J. F.; Hwang, C.; Fowell, S.; Plummer, C.

    2003-01-01

    The Consultative Committee for Space Data Systems is an international organization of national space agencies that is branching out to provide new standards to enhanced reuse of spacecraft equiptment and software. These Spacecraft Onboard Interface (SOIF) standards will be based on the well-known Internet protocols. this paper will review the SOIF standards by looking at the services that are being proposed for SOIF.

  8. WhatsApp Messenger as an Adjunctive Tool for Telemedicine: An Overview.

    Science.gov (United States)

    Giordano, Vincenzo; Koch, Hilton; Godoy-Santos, Alexandre; Dias Belangero, William; Esteves Santos Pires, Robinson; Labronici, Pedro

    2017-07-21

    The advent of telemedicine has allowed physicians to deliver medical treatment to patients from a distance. Mobile apps such as WhatsApp Messenger, an instant messaging service, came as a novel concept in all fields of social life, including medicine. The use of instant messaging services has been shown to improve communication within medical teams by providing means for quick teleconsultation, information sharing, and starting treatment as soon as possible. The aim of this study was to perform a comprehensive systematic review of present literature on the use of the WhatsApp Messenger app as an adjunctive health care tool for medical doctors. Searches were performed in PubMed, EMBASE, and the Cochrane Library using the term "whatsapp*" in articles published before January 2016. A bibliography of all relevant original articles that used the WhatsApp Messenger app was created. The level of evidence of each study was determined according to the Oxford Levels of Evidence ranking system produced by the Oxford Centre for Evidence-Based Medicine. The impact and the indications of WhatsApp Messenger are discussed in order to understand the extent to which this app currently functions as an adjunctive tool for telemedicine. The database search identified a total of 30 studies in which the term "whatsapp*" was used. Each article's list of references was evaluated item-by-item. After literature reviews, letters to the editor, and low-quality studies were excluded, a total of 10 studies were found to be eligible for inclusion. Of these studies, 9 had been published in the English language and 1 had been published in Spanish. Five were published by medical doctors. The pooled data presents compelling evidence that the WhatsApp Messenger app is a promising system, whether used as a communication tool between health care professionals, as a means of communication between health care professionals and the general public, or as a learning tool for providing health care information

  9. Engineered spacecraft deployables influenced by nature

    Science.gov (United States)

    Pohl, David; Wolpert, W. D.

    2009-08-01

    Northrop Grumman has been a leader in the space industry for over 50 years, and in fact was the first in the industry to produce a contractor-built spacecraft. Since the dawn of the Space Age and that Pioneer-1 spacecraft, every sub-system that makes up a spacecraft has grown in capability. One of the most visible changes to a spacecraft that enables these enhanced capabilities is the variety of appendages called deployable systems. These systems include solar arrays, antenna reflectors, telescopes and a current design for a tennis court sized sunshield. While the end product may look very different and perform different functions, all deployable systems share certain common attributes. Among these are: a latch mechanism for the deployable restraining it to the spacecraft for launch, an unlatching or release mechanism once orbit is achieved, an energy storage device or driving mechanism for deployment and a re-latching, or sometimes a repositioning device for orientation of the system during the mission. This paper describes these space-based systems and draws some comparisons with various natural analogs. While it may not be the case that the aerospace engineer is attempting to duplicate natural systems, it is almost certain that spacecraft deployable systems have been influenced by nature.

  10. Standardizing the information architecture for spacecraft operations

    Science.gov (United States)

    Easton, C. R.

    1994-01-01

    This paper presents an information architecture developed for the Space Station Freedom as a model from which to derive an information architecture standard for advanced spacecraft. The information architecture provides a way of making information available across a program, and among programs, assuming that the information will be in a variety of local formats, structures and representations. It provides a format that can be expanded to define all of the physical and logical elements that make up a program, add definitions as required, and import definitions from prior programs to a new program. It allows a spacecraft and its control center to work in different representations and formats, with the potential for supporting existing spacecraft from new control centers. It supports a common view of data and control of all spacecraft, regardless of their own internal view of their data and control characteristics, and of their communications standards, protocols and formats. This information architecture is central to standardizing spacecraft operations, in that it provides a basis for information transfer and translation, such that diverse spacecraft can be monitored and controlled in a common way.

  11. The first Messenger data supporting main theses of the wave planetology

    Science.gov (United States)

    Kochemasov, G. G.

    2008-09-01

    but also in granules amplitudes reflected in planetary relief range. It increases with the solar distances: Venus ~14, Earth ~20, Mars ~28-30 km. Without good topography on Mercury we theoretically assumed that this planet's relief range must be significantly lower (3-6 km) just to not violate the observed sequence (Fig. 2). The Messenger's measurements show that the real range does not exceed ~5 km. (small vertical relief differentiation is accompanied by small petrological differentiation expressed by a low albedo range, Fig. 2). One of Mercury's surprises is Caloris basin. Basins on planetary surfaces are normally lowlands filled with denser material (basalts for the terrestrial planets). Subsiding tectonic blocks - depressions - basins - occupying narrower and narrower space must be contracted, squeezed, wrinkled, rippled. This is confirmed in many occasions. But in the case of Caloris there is an extension confirmed by concentric and radial cracks. Uplifting and extending basin is a consequence of the wave tectonics. Waves have two phases (up and down) and a period after which the phases change. That is why initially subsided block - basin now (it started maybe a few milliards or hundreds millions years ago: the larger block - the longer wave phase period) experiences uplifting with extension. Is it the only case in the Solar system? Quite not. And Earth is a good example. Its southern mainly oceanic (thus subsided) hemisphere is filled with basalts, what is normal for planetary depressions. But precise geodynamic measurements show that the southern hemisphere increases lengths of its parallels that is expending. This dynamics is confirmed by widening modern planetary rifts in Atlantic, Indian ocean, Pacific in the southern direction and around Antarctic ("Southern" ocean) - a kind of the radial-concentric structure. A geochemical anomaly in oceanic basalts of this region ("DUPAL" anomaly after S.R. Hart, 1984) is characterized by relatively high Rb/Sr, Th/Pb, Th

  12. MESSENGER Observations of Extreme Loading and Unloading of Mercury's Magnetic Tail

    Science.gov (United States)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Korth, Haje; Krimigis, Stamatios M.; hide

    2010-01-01

    During MESSENGER's third flyby of Mercury, the magnetic field in the planet's magnetotail increased by factors of 2 to 3.5 over intervals of 2 to 3 min. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is approx.10 times less and typical durations are approx.1 hour. The extreme tail loading observed at Mercury implies that the relative intensity of sub storms must be much larger than at Earth. The correspondence between the duration of tail field enhancements and the characteristic time for the Dungey cycle, which describes plasma circulation through Mercury's magnetosphere. suggests that such circulation determines substorm timescale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles, but no acceleration signatures were seen during the MESSENGER flyby.

  13. Isolation and Translation of Hordein Messenger RNA from Wild Type and Mutant Endosperms in Barley

    DEFF Research Database (Denmark)

    Brandt, Anders Bøving; Ingwersen, J.

    1978-01-01

    Nucleotide sequences of four cDNA clones coding for the carboxy-terminal portion of at least two different B1 hordein polypeptides are presented. The open reading frame in the nucleotide sequence of the the largest clone (pc hor2-4, 720 nucleotides) translates into the 181 carboxy-terminal amino.......30 megadaltons. The 11S messenger RNA was translated in vitro into hordein precursor polypeptides which are 2–4 kilodaltons larger than the native hordein polypeptides. The endosperm cell of mutant No. 1508 contained twice as much RNA as the wild type endosperm cell but the same amount of polyadenylated 11S RNA....... The template activity of the latter was 10% of that found for the 11S hordein messenger RNA from the wild type and was limited to translation into one hordein precursor polypeptide....

  14. Effect of Thymine Starvation on Messenger Ribonucleic Acid Synthesis in Escherichia coli

    Science.gov (United States)

    Luzzati, Denise

    1966-01-01

    Luzzati, Denise (Institut de Biologie Physico-Chimique, Paris, France). Effect of thymine starvation on messenger ribonucleic acid synthesis in Escherichia coli. J. Bacteriol. 92:1435–1446. 1966.—During the course of thymine starvation, the rate of synthesis of messenger ribonucleic acid (mRNA, the rapidly labeled fraction of the RNA which decays in the presence of dinitrophenol or which hybridizes with deoxyribonucleic acid) decreases exponentially, in parallel with the viability of the thymine-starved bacteria. The ability of cell-free extracts of starved bacteria to incorporate ribonucleoside triphosphates into RNA was determined; it was found to be inferior to that of extracts from control cells. The analysis of the properties of cell-free extracts of starved cells shows that their decreased RNA polymerase activity is the consequence of a modification of their deoxyribonucleic acid, the ability of which to serve as a template for RNA polymerase decreases during starvation. PMID:5332402

  15. Comment on "Length-dependent translation of messenger RNA by ribosomes"

    CERN Document Server

    Zhang, Yunxin

    2011-01-01

    In recent paper [Phys. Rev. E {\\bf 83}, 042903 (2011)], a simple model for the translation of messenger RNA by ribosomes is provided, and the expression of translational ratio of protein is given. In this comments, varied methods to get this ratio are addressed. Depending on a different method, we find that, roughly speaking, this translational ratio decays exponentially with mRNA length in prokaryotic cell, and reciprocally with mRNA length in eukaryotic cells.

  16. Second Messenger Signaling in Bacillus subtilis: Accumulation of Cyclic di-AMP Inhibits Biofilm Formation.

    Science.gov (United States)

    Gundlach, Jan; Rath, Hermann; Herzberg, Christina; Mäder, Ulrike; Stülke, Jörg

    2016-01-01

    The Gram-positive model organism Bacillus subtilis produces the essential second messenger signaling nucleotide cyclic di-AMP. In B. subtilis and other bacteria, c-di-AMP has been implicated in diverse functions such as control of metabolism, cell division and cell wall synthesis, and potassium transport. To enhance our understanding of the multiple functions of this second messenger, we have studied the consequences of c-di-AMP accumulation at a global level by a transcriptome analysis. C-di-AMP accumulation affected the expression of about 700 genes, among them the two major operons required for biofilm formation. The expression of both operons was severely reduced both in the laboratory and a non-domesticated strain upon accumulation of c-di-AMP. In excellent agreement, the corresponding strain was unable to form complex colonies. In B. subtilis, the transcription factor SinR controls the expression of biofilm genes by binding to their promoter regions resulting in transcription repression. Inactivation of the sinR gene restored biofilm formation even at high intracellular c-di-AMP concentrations suggesting that the second messenger acts upstream of SinR in the signal transduction pathway. As c-di-AMP accumulation did not affect the intracellular levels of SinR, we conclude that the nucleotide affects the activity of SinR.

  17. Optimal and fast \\cal {E}/\\cal {B} separation with a dual messenger field

    Science.gov (United States)

    Ramanah, Doogesh Kodi; Lavaux, Guilhem; Wandelt, Benjamin D.

    2018-02-01

    We adapt our recently proposed dual messenger algorithm for spin field reconstruction and showcase its efficiency and effectiveness in Wiener filtering polarized cosmic microwave background (CMB) maps. Unlike conventional preconditioned conjugate gradient (PCG) solvers, our preconditioner-free technique can deal with high-resolution joint temperature and polarization maps with inhomogeneous noise distributions and arbitrary mask geometries with relative ease. Various convergence diagnostics illustrate the high quality of the dual messenger reconstruction. In contrast, the PCG implementation fails to converge to a reasonable solution for the specific problem considered. The implementation of the dual messenger method is straightforward and guarantees numerical stability and convergence. We show how the algorithm can be modified to generate fluctuation maps, which, combined with the Wiener filter solution, yield unbiased constrained signal realizations, consistent with observed data. This algorithm presents a pathway to exact global analyses of high-resolution and high-sensitivity CMB data for a statistically optimal separation of \\cal {E} and \\cal {B} modes. It is therefore relevant for current and next-generation CMB experiments, in the quest for the elusive primordial \\cal {B}-mode signal.

  18. Optimal and fast E/B separation with a dual messenger field

    Science.gov (United States)

    Ramanah, Doogesh Kodi; Lavaux, Guilhem; Wandelt, Benjamin D.

    2018-02-01

    We adapt our recently proposed dual messenger algorithm for spin field reconstruction and showcase its efficiency and effectiveness in Wiener filtering polarized cosmic microwave background (CMB) maps. Unlike conventional preconditioned conjugate gradient (PCG) solvers, our preconditioner-free technique can deal with high-resolution joint temperature and polarization maps with inhomogeneous noise distributions and arbitrary mask geometries with relative ease. Various convergence diagnostics illustrate the high quality of the dual messenger reconstruction. In contrast, the PCG implementation fails to converge to a reasonable solution for the specific problem considered. The implementation of the dual messenger method is straightforward and guarantees numerical stability and convergence. We show how the algorithm can be modified to generate fluctuation maps, which, combined with the Wiener filter solution, yield unbiased constrained signal realizations, consistent with observed data. This algorithm presents a pathway to exact global analyses of high-resolution and high-sensitivity CMB data for a statistically optimal separation of E and B modes. It is therefore relevant for current and next-generation CMB experiments, in the quest for the elusive primordial B-mode signal.

  19. Dashboard Monitoring System Berbasis Web Sebagai Pemantau Layanan liteBIG Instant Messenger

    Directory of Open Access Journals (Sweden)

    Gigih Forda Nama

    2017-04-01

    Full Text Available Saat ini hampir semua pengguna ponsel pintar menggunakan layanan perpesanan instan sebagai media komunikasi dikarenakan layanan perpesanan instan lebih hemat biaya dengan hanya menggunakan jaringan internet dibandingkan layanan pesan singkat (SMS. Layanan yang diberikan harus dapat melayani pengguna dengan baik agar pesan yang dikirim oleh pengirim dapat diterima oleh penerima dengan cepat dan akurat. Layanan ini juga harus dijaga keandalannya untuk menjamin kualitas pelayanan dan untuk menghindari ketidaknyamanan pengguna. Sehingga, diperlukan adanya sistem pemantauan berupa perangkat lunak untuk pengawasan status layanan setiap saat dapat diakses dari manapun dan kapanpun. PT.Sandika Cahaya Mandiri memiliki produk layanan perpesanan instan dengan brand name liteBIG Messenger. Perusahaan ini memerlukan perangkat lunak untuk pemantauan layanan liteBIG Messenger. Dengan adanya perangkat lunak pemantauan layanan, petugas pemantauan dapat melihat secara realtime status layanan utama pada setiap komputer server, pemakaian sumber daya (cpu, memory, dan harddisk, dan statistik pengguna baru liteBIG Messenger  melalui antarmuka web. Petugas pemantauan juga akan mendapat pemberitahuan ketika terjadi masalah pada layanan sehingga masalah dapat lebih dini diketahui dan downtime dapat dikurangi.

  20. Multi-messenger Observations of a Binary Neutron Star Merger

    Science.gov (United States)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; AultONeal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Barthelmy, S. D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H.-P.; Chia, H.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M., Jr.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D’Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; De, S.; DeBra, D.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; De Pietri, R.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; De Rossi, C.; DeSalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Griswold, B.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Larson, S. L.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Marsh, P.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, P.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O’Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O’Reilly, B.; Ormiston, R.; Ortega, L. F.; O’Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Wessels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zimmerman, A. B.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Wilson-Hodge, C. A.; Bissaldi, E.; Blackburn, L.; Briggs, M. S.; Burns, E.; Cleveland, W. H.; Connaughton, V.; Gibby, M. H.; Giles, M. M.; Goldstein, A.; Hamburg, R.; Jenke, P.; Hui, C. M.; Kippen, R. M.; Kocevski, D.; McBreen, S.; Meegan, C. A.; Paciesas, W. S.; Poolakkil, S.; Preece, R. D.; Racusin, J.; Roberts, O. J.; Stanbro, M.; Veres, P.; von Kienlin, A.; GBM, Fermi; Savchenko, V.; Ferrigno, C.; Kuulkers, E.; Bazzano, A.; Bozzo, E.; Brandt, S.; Chenevez, J.; Courvoisier, T. J.-L.; Diehl, R.; Domingo, A.; Hanlon, L.; Jourdain, E.; Laurent, P.; Lebrun, F.; Lutovinov, A.; Martin-Carrillo, A.; Mereghetti, S.; Natalucci, L.; Rodi, J.; Roques, J.-P.; Sunyaev, R.; Ubertini, P.; INTEGRAL; Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Samarai, I. Al; Altmann, D.; Andeen, K.; Anderson, T.; Ansseau, I.; Anton, G.; Argüelles, C.; Auffenberg, J.; Axani, S.; Bagherpour, H.; Bai, X.; Barron, J. P.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Bernardini, E.; Besson, D. Z.; Binder, G.; Bindig, D.; Blaufuss, E.; Blot, S.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Bourbeau, E.; Bourbeau, J.; Bradascio, F.; Braun, J.; Brayeur, L.; Brenzke, M.; Bretz, H.-P.; Bron, S.; Brostean-Kaiser, J.; Burgman, A.; Carver, T.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cross, R.; Day, M.; de André, J. P. A. M.; De Clercq, C.; DeLaunay, J. J.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Dvorak, E.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Eller, P.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Franckowiak, A.; Friedman, E.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Giang, W.; Glauch, T.; Glüsenkamp, T.; Goldschmidt, A.; Gonzalez, J. G.; Grant, D.; Griffith, Z.; Haack, C.; Hallgren, A.; Halzen, F.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Hokanson-Fasig, B.; Hoshina, K.; Huang, F.; Huber, M.; Hultqvist, K.; Hünnefeld, M.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Kalaczynski, P.; Kang, W.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kheirandish, A.; Kim, J.; Kim, M.; Kintscher, T.; Kiryluk, J.; Kittler, T.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koschinsky, J. P.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, M.; Krückl, G.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Kyriacou, A.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lauber, F.; Lesiak-Bzdak, M.; Leuermann, M.; Liu, Q. R.; Lu, L.; Lünemann, J.; Luszczak, W.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mancina, S.; Maruyama, R.; Mase, K.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Micallef, J.; Momenté, G.; Montaruli, T.; Moore, R. W.; Moulai, M.; Nahnhauer, R.; Nakarmi, P.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; O’Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Peiffer, P.; Pepper, J. A.; Pérez de los Heros, C.; Pieloth, D.; Pinat, E.; Price, P. B.; Przybylski, G. T.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Rea, I. C.; Reimann, R.; Relethford, B.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Rysewyk, D.; Sälzer, T.; Sanchez Herrera, S. E.; Sandrock, A.; Sandroos, J.; Santander, M.; Sarkar, S.; Sarkar, S.; Satalecka, K.; Schlunder, P.; Schmidt, T.; Schneider, A.; Schoenen, S.; Schöneberg, S.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soedingrekso, J.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stachurska, J.; Stamatikos, M.; Stanev, T.; Stasik, A.; Stettner, J.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stössl, A.; Strotjohann, N. L.; Stuttard, T.; Sullivan, G. W.; Sutherland, M.; Taboada, I.; Tatar, J.; Tenholt, F.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Tung, C. F.; Turcati, A.; Turley, C. F.; Ty, B.; Unger, E.; Usner, M.; Vandenbroucke, J.; Van Driessche, W.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Vehring, M.; Vogel, E.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandler, F. D.; Wandkowsky, N.; Waza, A.; Weaver, C.; Weiss, M. J.; Wendt, C.; Werthebach, J.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wolf, M.; Wood, T. R.; Woolsey, E.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Yuan, T.; Zoll, M.; IceCube Collaboration; Balasubramanian, A.; Mate, S.; Bhalerao, V.; Bhattacharya, D.; Vibhute, A.; Dewangan, G. C.; Rao, A. R.; Vadawale, S. V.; AstroSat Cadmium Zinc Telluride Imager Team; Svinkin, D. S.; Hurley, K.; Aptekar, R. L.; Frederiks, D. D.; Golenetskii, S. V.; Kozlova, A. V.; Lysenko, A. L.; Oleynik, Ph. P.; Tsvetkova, A. E.; Ulanov, M. V.; Cline, T.; IPN Collaboration; Li, T. P.; Xiong, S. L.; Zhang, S. N.; Lu, F. J.; Song, L. M.; Cao, X. L.; Chang, Z.; Chen, G.; Chen, L.; Chen, T. X.; Chen, Y.; Chen, Y. B.; Chen, Y. P.; Cui, W.; Cui, W. W.; Deng, J. K.; Dong, Y. W.; Du, Y. Y.; Fu, M. X.; Gao, G. H.; Gao, H.; Gao, M.; Ge, M. Y.; Gu, Y. D.; Guan, J.; Guo, C. C.; Han, D. W.; Hu, W.; Huang, Y.; Huo, J.; Jia, S. M.; Jiang, L. H.; Jiang, W. C.; Jin, J.; Jin, Y. J.; Li, B.; Li, C. K.; Li, G.; Li, M. S.; Li, W.; Li, X.; Li, X. B.; Li, X. F.; Li, Y. G.; Li, Z. J.; Li, Z. W.; Liang, X. H.; Liao, J. Y.; Liu, C. Z.; Liu, G. Q.; Liu, H. W.; Liu, S. Z.; Liu, X. J.; Liu, Y.; Liu, Y. N.; Lu, B.; Lu, X. F.; Luo, T.; Ma, X.; Meng, B.; Nang, Y.; Nie, J. Y.; Ou, G.; Qu, J. L.; Sai, N.; Sun, L.; Tan, Y.; Tao, L.; Tao, W. H.; Tuo, Y. L.; Wang, G. F.; Wang, H. Y.; Wang, J.; Wang, W. S.; Wang, Y. S.; Wen, X. Y.; Wu, B. B.; Wu, M.; Xiao, G. C.; Xu, H.; Xu, Y. P.; Yan, L. L.; Yang, J. W.; Yang, S.; Yang, Y. J.; Zhang, A. M.; Zhang, C. L.; Zhang, C. M.; Zhang, F.; Zhang, H. M.; Zhang, J.; Zhang, Q.; Zhang, S.; Zhang, T.; Zhang, W.; Zhang, W. C.; Zhang, W. Z.; Zhang, Y.; Zhang, Y.; Zhang, Y. F.; Zhang, Y. J.; Zhang, Z.; Zhang, Z. L.; Zhao, H. S.; Zhao, J. L.; Zhao, X. F.; Zheng, S. J.; Zhu, Y.; Zhu, Y. X.; Zou, C. L.; The Insight-HXMT Collaboration; Albert, A.; André, M.; Anghinolfi, M.; Ardid, M.; Aubert, J.-J.; Aublin, J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Belhorma, B.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M. C.; Brânzaş, H.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Cherkaoui El Moursli, R.; Chiarusi, T.; Circella, M.; Coelho, J. A. B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Díaz, A. F.; Deschamps, A.; De Bonis, G.; Distefano, C.; Di Palma, I.; Domi, A.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; El Khayati, N.; Elsässer, D.; Enzenhöfer, A.; Ettahiri, A.; Fassi, F.; Felis, I.; Fusco, L. A.; Gay, P.; Giordano, V.; Glotin, H.; Grégoire, T.; Ruiz, R. Gracia; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hössl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kiessling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Navas, S.; Nezri, E.; Organokov, M.; Păvălaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Turpin, D.; Tönnis, C.; Vallage, B.; Van Elewyck, V.; Versari, F.; Vivolo, D.; Vizzoca, A.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.; ANTARES Collaboration; Beardmore, A. P.; Breeveld, A. A.; Burrows, D. N.; Cenko, S. B.; Cusumano, G.; D’Aì, A.; de Pasquale, M.; Emery, S. W. K.; Evans, P. A.; Giommi, P.; Gronwall, C.; Kennea, J. A.; Krimm, H. A.; Kuin, N. P. M.; Lien, A.; Marshall, F. E.; Melandri, A.; Nousek, J. A.; Oates, S. R.; Osborne, J. P.; Pagani, C.; Page, K. L.; Palmer, D. M.; Perri, M.; Siegel, M. H.; Sbarufatti, B.; Tagliaferri, G.; Tohuvavohu, A.; The Swift Collaboration; Tavani, M.; Verrecchia, F.; Bulgarelli, A.; Evangelista, Y.; Pacciani, L.; Feroci, M.; Pittori, C.; Giuliani, A.; Del Monte, E.; Donnarumma, I.; Argan, A.; Trois, A.; Ursi, A.; Cardillo, M.; Piano, G.; Longo, F.; Lucarelli, F.; Munar-Adrover, P.; Fuschino, F.; Labanti, C.; Marisaldi, M.; Minervini, G.; Fioretti, V.; Parmiggiani, N.; Gianotti, F.; Trifoglio, M.; Di Persio, G.; Antonelli, L. A.; Barbiellini, G.; Caraveo, P.; Cattaneo, P. W.; Costa, E.; Colafrancesco, S.; D’Amico, F.; Ferrari, A.; Morselli, A.; Paoletti, F.; Picozza, P.; Pilia, M.; Rappoldi, A.; Soffitta, P.; Vercellone, S.; AGILE Team; Foley, R. J.; Coulter, D. A.; Kilpatrick, C. D.; Drout, M. R.; Piro, A. L.; Shappee, B. J.; Siebert, M. R.; Simon, J. D.; Ulloa, N.; Kasen, D.; Madore, B. F.; Murguia-Berthier, A.; Pan, Y.-C.; Prochaska, J. X.; Ramirez-Ruiz, E.; Rest, A.; Rojas-Bravo, C.; The 1M2H Team; Berger, E.; Soares-Santos, M.; Annis, J.; Alexander, K. D.; Allam, S.; Balbinot, E.; Blanchard, P.; Brout, D.; Butler, R. E.; Chornock, R.; Cook, E. R.; Cowperthwaite, P.; Diehl, H. T.; Drlica-Wagner, A.; Drout, M. R.; Durret, F.; Eftekhari, T.; Finley, D. A.; Fong, W.; Frieman, J. A.; Fryer, C. L.; García-Bellido, J.; Gruendl, R. A.; Hartley, W.; Herner, K.; Kessler, R.; Lin, H.; Lopes, P. A. A.; Lourenço, A. C. C.; Margutti, R.; Marshall, J. L.; Matheson, T.; Medina, G. E.; Metzger, B. D.; Muñoz, R. R.; Muir, J.; Nicholl, M.; Nugent, P.; Palmese, A.; Paz-Chinchón, F.; Quataert, E.; Sako, M.; Sauseda, M.; Schlegel, D. J.; Scolnic, D.; Secco, L. F.; Smith, N.; Sobreira, F.; Villar, V. A.; Vivas, A. K.; Wester, W.; Williams, P. K. G.; Yanny, B.; Zenteno, A.; Zhang, Y.; Abbott, T. M. C.; Banerji, M.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Castander, F. J.; Crocce, M.; Cunha, C. E.; D’Andrea, C. B.; da Costa, L. N.; Davis, C.; DePoy, D. L.; Desai, S.; Dietrich, J. P.; Eifler, T. F.; Fernandez, E.; Flaugher, B.; Fosalba, P.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruen, D.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D. J.; Jeltema, T.; Johnson, M. W. G.; Johnson, M. D.; Kent, S.; Krause, E.; Kron, R.; Kuehn, K.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Martini, P.; McMahon, R. G.; Menanteau, F.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, M.; Smith, R. C.; Stebbins, A.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, R. C.; Troxel, M. A.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Wechsler, R. H.; Weller, J.; Carlin, J. L.; Gill, M. S. S.; Li, T. S.; Marriner, J.; Neilsen, E.; The Dark Energy Camera GW-EM Collaboration; the DES Collaboration; Haislip, J. B.; Kouprianov, V. V.; Reichart, D. E.; Sand, D. J.; Tartaglia, L.; Valenti, S.; Yang, S.; The DLT40 Collaboration; Benetti, S.; Brocato, E.; Campana, S.; Cappellaro, E.; Covino, S.; D’Avanzo, P.; D’Elia, V.; Getman, F.; Ghirlanda, G.; Ghisellini, G.; Limatola, L.; Nicastro, L.; Palazzi, E.; Pian, E.; Piranomonte, S.; Possenti, A.; Rossi, A.; Salafia, O. S.; Tomasella, L.; Amati, L.; Antonelli, L. A.; Bernardini, M. G.; Bufano, F.; Capaccioli, M.; Casella, P.; Dadina, M.; De Cesare, G.; Di Paola, A.; Giuffrida, G.; Giunta, A.; Israel, G. L.; Lisi, M.; Maiorano, E.; Mapelli, M.; Masetti, N.; Pescalli, A.; Pulone, L.; Salvaterra, R.; Schipani, P.; Spera, M.; Stamerra, A.; Stella, L.; Testa, V.; Turatto, M.; Vergani, D.; Aresu, G.; Bachetti, M.; Buffa, F.; Burgay, M.; Buttu, M.; Caria, T.; Carretti, E.; Casasola, V.; Castangia, P.; Carboni, G.; Casu, S.; Concu, R.; Corongiu, A.; Deiana, G. L.; Egron, E.; Fara, A.; Gaudiomonte, F.; Gusai, V.; Ladu, A.; Loru, S.; Leurini, S.; Marongiu, L.; Melis, A.; Melis, G.; Migoni, Carlo; Milia, Sabrina; Navarrini, Alessandro; Orlati, A.; Ortu, P.; Palmas, S.; Pellizzoni, A.; Perrodin, D.; Pisanu, T.; Poppi, S.; Righini, S.; Saba, A.; Serra, G.; Serrau, M.; Stagni, M.; Surcis, G.; Vacca, V.; Vargiu, G. P.; Hunt, L. K.; Jin, Z. P.; Klose, S.; Kouveliotou, C.; Mazzali, P. A.; Møller, P.; Nava, L.; Piran, T.; Selsing, J.; Vergani, S. D.; Wiersema, K.; Toma, K.; Higgins, A. B.; Mundell, C. G.; di Serego Alighieri, S.; Gótz, D.; Gao, W.; Gomboc, A.; Kaper, L.; Kobayashi, S.; Kopac, D.; Mao, J.; Starling, R. L. C.; Steele, I.; van der Horst, A. J.; GRAWITA: GRAvitational Wave Inaf TeAm; Acero, F.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Berenji, B.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Bregeon, J.; Buehler, R.; Buson, S.; Cameron, R. A.; Caputo, R.; Caraveo, P. A.; Cavazzuti, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Cohen-Tanugi, J.; Cominsky, L. R.; Costantin, D.; Cuoco, A.; D’Ammando, F.; de Palma, F.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Dubois, R.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Green, D.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Horan, D.; Jóhannesson, G.; Kamae, T.; Kensei, S.; Kuss, M.; La Mura, G.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda, A.; Mazziotta, M. N.; McEnery, J. E.; Meyer, M.; Michelson, P. F.; Mirabal, N.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ojha, R.; Omodei, N.; Orienti, M.; Orlando, E.; Palatiello, M.; Paliya, V. S.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Saz Parkinson, P. M.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Suson, D. J.; Takahashi, M.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Torresi, E.; Troja, E.; Venters, T. M.; Vianello, G.; Zaharijas, G.; The Fermi Large Area Telescope Collaboration; Allison, J. R.; Bannister, K. W.; Dobie, D.; Kaplan, D. L.; Lenc, E.; Lynch, C.; Murphy, T.; Sadler, E. M.; Australia Telescope Compact Array, ATCA:; Hotan, A.; James, C. W.; Oslowski, S.; Raja, W.; Shannon, R. M.; Whiting, M.; Australian SKA Pathfinder, ASKAP:; Arcavi, I.; Howell, D. A.; McCully, C.; Hosseinzadeh, G.; Hiramatsu, D.; Poznanski, D.; Barnes, J.; Zaltzman, M.; Vasylyev, S.; Maoz, D.; Las Cumbres Observatory Group; Cooke, J.; Bailes, M.; Wolf, C.; Deller, A. T.; Lidman, C.; Wang, L.; Gendre, B.; Andreoni, I.; Ackley, K.; Pritchard, T. A.; Bessell, M. S.; Chang, S.-W.; Möller, A.; Onken, C. A.; Scalzo, R. A.; Ridden-Harper, R.; Sharp, R. G.; Tucker, B. E.; Farrell, T. J.; Elmer, E.; Johnston, S.; Venkatraman Krishnan, V.; Keane, E. F.; Green, J. A.; Jameson, A.; Hu, L.; Ma, B.; Sun, T.; Wu, X.; Wang, X.; Shang, Z.; Hu, Y.; Ashley, M. C. B.; Yuan, X.; Li, X.; Tao, C.; Zhu, Z.; Zhang, H.; Suntzeff, N. B.; Zhou, J.; Yang, J.; Orange, B.; Morris, D.; Cucchiara, A.; Giblin, T.; Klotz, A.; Staff, J.; Thierry, P.; Schmidt, B. P.; OzGrav; (Deeper, DWF; Wider; program, Faster; AST3; CAASTRO Collaborations; Tanvir, N. R.; Levan, A. J.; Cano, Z.; de Ugarte-Postigo, A.; González-Fernández, C.; Greiner, J.; Hjorth, J.; Irwin, M.; Krühler, T.; Mandel, I.; Milvang-Jensen, B.; O’Brien, P.; Rol, E.; Rosetti, S.; Rosswog, S.; Rowlinson, A.; Steeghs, D. T. H.; Thöne, C. C.; Ulaczyk, K.; Watson, D.; Bruun, S. H.; Cutter, R.; Figuera Jaimes, R.; Fujii, Y. I.; Fruchter, A. S.; Gompertz, B.; Jakobsson, P.; Hodosan, G.; Jèrgensen, U. G.; Kangas, T.; Kann, D. A.; Rabus, M.; Schrøder, S. L.; Stanway, E. R.; Wijers, R. A. M. J.; The VINROUGE Collaboration; Lipunov, V. M.; Gorbovskoy, E. S.; Kornilov, V. G.; Tyurina, N. V.; Balanutsa, P. V.; Kuznetsov, A. S.; Vlasenko, D. M.; Podesta, R. C.; Lopez, C.; Podesta, F.; Levato, H. O.; Saffe, C.; Mallamaci, C. C.; Budnev, N. M.; Gress, O. A.; Kuvshinov, D. A.; Gorbunov, I. A.; Vladimirov, V. V.; Zimnukhov, D. S.; Gabovich, A. V.; Yurkov, V. V.; Sergienko, Yu. P.; Rebolo, R.; Serra-Ricart, M.; Tlatov, A. G.; Ishmuhametova, Yu. V.; MASTER Collaboration; Abe, F.; Aoki, K.; Aoki, W.; Asakura, Y.; Baar, S.; Barway, S.; Bond, I. A.; Doi, M.; Finet, F.; Fujiyoshi, T.; Furusawa, H.; Honda, S.; Itoh, R.; Kanda, N.; Kawabata, K. S.; Kawabata, M.; Kim, J. H.; Koshida, S.; Kuroda, D.; Lee, C.-H.; Liu, W.; Matsubayashi, K.; Miyazaki, S.; Morihana, K.; Morokuma, T.; Motohara, K.; Murata, K. L.; Nagai, H.; Nagashima, H.; Nagayama, T.; Nakaoka, T.; Nakata, F.; Ohsawa, R.; Ohshima, T.; Ohta, K.; Okita, H.; Saito, T.; Saito, Y.; Sako, S.; Sekiguchi, Y.; Sumi, T.; Tajitsu, A.; Takahashi, J.; Takayama, M.; Tamura, Y.; Tanaka, I.; Tanaka, M.; Terai, T.; Tominaga, N.; Tristram, P. J.; Uemura, M.; Utsumi, Y.; Yamaguchi, M. S.; Yasuda, N.; Yoshida, M.; Zenko, T.; J-GEM; Adams, S. M.; Anupama, G. C.; Bally, J.; Barway, S.; Bellm, E.; Blagorodnova, N.; Cannella, C.; Chandra, P.; Chatterjee, D.; Clarke, T. E.; Cobb, B. E.; Cook, D. O.; Copperwheat, C.; De, K.; Emery, S. W. K.; Feindt, U.; Foster, K.; Fox, O. D.; Frail, D. A.; Fremling, C.; Frohmaier, C.; Garcia, J. A.; Ghosh, S.; Giacintucci, S.; Goobar, A.; Gottlieb, O.; Grefenstette, B. W.; Hallinan, G.; Harrison, F.; Heida, M.; Helou, G.; Ho, A. Y. Q.; Horesh, A.; Hotokezaka, K.; Ip, W.-H.; Itoh, R.; Jacobs, Bob; Jencson, J. E.; Kasen, D.; Kasliwal, M. M.; Kassim, N. E.; Kim, H.; Kiran, B. S.; Kuin, N. P. M.; Kulkarni, S. R.; Kupfer, T.; Lau, R. M.; Madsen, K.; Mazzali, P. A.; Miller, A. A.; Miyasaka, H.; Mooley, K.; Myers, S. T.; Nakar, E.; Ngeow, C.-C.; Nugent, P.; Ofek, E. O.; Palliyaguru, N.; Pavana, M.; Perley, D. A.; Peters, W. M.; Pike, S.; Piran, T.; Qi, H.; Quimby, R. M.; Rana, J.; Rosswog, S.; Rusu, F.; Sadler, E. M.; Van Sistine, A.; Sollerman, J.; Xu, Y.; Yan, L.; Yatsu, Y.; Yu, P.-C.; Zhang, C.; Zhao, W.; GROWTH; JAGWAR; Caltech-NRAO; TTU-NRAO; NuSTAR Collaborations; Chambers, K. C.; Huber, M. E.; Schultz, A. S. B.; Bulger, J.; Flewelling, H.; Magnier, E. A.; Lowe, T. B.; Wainscoat, R. J.; Waters, C.; Willman, M.; Pan-STARRS; Ebisawa, K.; Hanyu, C.; Harita, S.; Hashimoto, T.; Hidaka, K.; Hori, T.; Ishikawa, M.; Isobe, N.; Iwakiri, W.; Kawai, H.; Kawai, N.; Kawamuro, T.; Kawase, T.; Kitaoka, Y.; Makishima, K.; Matsuoka, M.; Mihara, T.; Morita, T.; Morita, K.; Nakahira, S.; Nakajima, M.; Nakamura, Y.; Negoro, H.; Oda, S.; Sakamaki, A.; Sasaki, R.; Serino, M.; Shidatsu, M.; Shimomukai, R.; Sugawara, Y.; Sugita, S.; Sugizaki, M.; Tachibana, Y.; Takao, Y.; Tanimoto, A.; Tomida, H.; Tsuboi, Y.; Tsunemi, H.; Ueda, Y.; Ueno, S.; Yamada, S.; Yamaoka, K.; Yamauchi, M.; Yatabe, F.; Yoneyama, T.; Yoshii, T.; The MAXI Team; Coward, D. M.; Crisp, H.; Macpherson, D.; Andreoni, I.; Laugier, R.; Noysena, K.; Klotz, A.; Gendre, B.; Thierry, P.; Turpin, D.; Consortium, TZAC; Im, M.; Choi, C.; Kim, J.; Yoon, Y.; Lim, G.; Lee, S.-K.; Lee, C.-U.; Kim, S.-L.; Ko, S.-W.; Joe, J.; Kwon, M.-K.; Kim, P.-J.; Lim, S.-K.; Choi, J.-S.; KU Collaboration; Fynbo, J. P. U.; Malesani, D.; Xu, D.; Optical Telescope, Nordic; Smartt, S. J.; Jerkstrand, A.; Kankare, E.; Sim, S. A.; Fraser, M.; Inserra, C.; Maguire, K.; Leloudas, G.; Magee, M.; Shingles, L. J.; Smith, K. W.; Young, D. R.; Kotak, R.; Gal-Yam, A.; Lyman, J. D.; Homan, D. S.; Agliozzo, C.; Anderson, J. P.; Angus, C. R.; Ashall, C.; Barbarino, C.; Bauer, F. E.; Berton, M.; Botticella, M. T.; Bulla, M.; Cannizzaro, G.; Cartier, R.; Cikota, A.; Clark, P.; De Cia, A.; Della Valle, M.; Dennefeld, M.; Dessart, L.; Dimitriadis, G.; Elias-Rosa, N.; Firth, R. E.; Flörs, A.; Frohmaier, C.; Galbany, L.; González-Gaitán, S.; Gromadzki, M.; Gutiérrez, C. P.; Hamanowicz, A.; Harmanen, J.; Heintz, K. E.; Hernandez, M.-S.; Hodgkin, S. T.; Hook, I. M.; Izzo, L.; James, P. A.; Jonker, P. G.; Kerzendorf, W. E.; Kostrzewa-Rutkowska, Z.; Kromer, M.; Kuncarayakti, H.; Lawrence, A.; Manulis, I.; Mattila, S.; McBrien, O.; Müller, A.; Nordin, J.; O’Neill, D.; Onori, F.; Palmerio, J. T.; Pastorello, A.; Patat, F.; Pignata, G.; Podsiadlowski, P.; Razza, A.; Reynolds, T.; Roy, R.; Ruiter, A. J.; Rybicki, K. A.; Salmon, L.; Pumo, M. L.; Prentice, S. J.; Seitenzahl, I. R.; Smith, M.; Sollerman, J.; Sullivan, M.; Szegedi, H.; Taddia, F.; Taubenberger, S.; Terreran, G.; Van Soelen, B.; Vos, J.; Walton, N. A.; Wright, D. E.; Wyrzykowski, Ł.; Yaron, O.; pre="(">ePESSTO,

    2017-10-01

    On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼ 1.7 {{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of {40}-8+8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 {M}ȯ . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 {{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

  1. MESSENGER E/V/H MLA 3/4 CDR/RDR DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Mercury Laser Altimeter (MLA) Calibrated Data Record (CDR) and Reduced Data Record (RDR) products. The MLA...

  2. MESSENGER E/V/H MLA 3/4 CDR/RDR DATA V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER Mercury Laser Altimeter (MLA) Reduced Data Record (RDR) products. The MLA is a solid-state pulsed laser...

  3. Modeling the fundamental characteristics and processes of the spacecraft functioning

    Science.gov (United States)

    Bazhenov, V. I.; Osin, M. I.; Zakharov, Y. V.

    1986-01-01

    The fundamental aspects of modeling of spacecraft characteristics by using computing means are considered. Particular attention is devoted to the design studies, the description of physical appearance of the spacecraft, and simulated modeling of spacecraft systems. The fundamental questions of organizing the on-the-ground spacecraft testing and the methods of mathematical modeling were presented.

  4. Spacecraft Attitude Maneuver Planning Using Genetic Algorithms

    Science.gov (United States)

    Kornfeld, Richard P.

    2004-01-01

    A key enabling technology that leads to greater spacecraft autonomy is the capability to autonomously and optimally slew the spacecraft from and to different attitudes while operating under a number of celestial and dynamic constraints. The task of finding an attitude trajectory that meets all the constraints is a formidable one, in particular for orbiting or fly-by spacecraft where the constraints and initial and final conditions are of time-varying nature. This approach for attitude path planning makes full use of a priori constraint knowledge and is computationally tractable enough to be executed onboard a spacecraft. The approach is based on incorporating the constraints into a cost function and using a Genetic Algorithm to iteratively search for and optimize the solution. This results in a directed random search that explores a large part of the solution space while maintaining the knowledge of good solutions from iteration to iteration. A solution obtained this way may be used as is or as an initial solution to initialize additional deterministic optimization algorithms. A number of representative case examples for time-fixed and time-varying conditions yielded search times that are typically on the order of minutes, thus demonstrating the viability of this method. This approach is applicable to all deep space and planet Earth missions requiring greater spacecraft autonomy, and greatly facilitates navigation and science observation planning.

  5. INSTANT MESSENGER (IM) APPLICATION USAGE AT WORKPLACE AND WORKING CULTURE OF A PUBLIC UNIVERSITY SUPPORTING STAFF IN KOTA KINABALU SABAH.

    OpenAIRE

    Nading, Dorina; Morshidi, Azizan

    2016-01-01

    Instant Messenger (IM) has becoming a new form of social relations tool in which people interact, dialogue, collaborate and exchange information. Many organizations and companies have adapted their management strategies with the utilization of IM applications, both internally or externally. The popularity of IM in local organizational management in such a way that government agencies, companies, universities, colleges and schools. The use of applications such as wechat, whatsApp messenger...

  6. On cryptographic security of end-to-end encrypted connections in WhatsApp and Telegram messengers

    Directory of Open Access Journals (Sweden)

    Sergey V. Zapechnikov

    2017-11-01

    Full Text Available The aim of this work is to analyze the available possibilities for improving secure messaging with end-to-end connections under conditions of external violator actions and distrusted service provider. We made a comparative analysis of cryptographic security mechanisms for two widely used messengers: Telegram and WhatsApp. It was found that Telegram is based on MTProto protocol, while WhatsApp is based on the alternative Signal protocol. We examine the specific features of messengers implementation associated with random number generation on the most popular Android mobile platform. It was shown that Signal has better security properties. It is used in several other popular messengers such as TextSecure, RedPhone, GoogleAllo, FacebookMessenger, Signal along with WhatsApp. A number of possible attacks on both messengers were analyzed in details. In particular, we demonstrate that the metadata are poorly protected in both messengers. Metadata security may be one of the goals for further studies.

  7. Singular control in minimum time spacecraft reorientation

    Science.gov (United States)

    Seywald, Hans; Kumar, Renjith R.

    1991-01-01

    Spacecraft reorientation is investigated numerically for an inertially symmetric rigid spacecraft with three bounded independent control torques aligned with the principal axes. The dynamical system of the spacecraft and the framework of the optimal-control problem are established in order to identify all of the potential strategies. The investigation lists bang-bang solutions and finite-order and infinite-order singular arcs, and the conditions for the finite-order singular arcs are given. Numerical examples are developed for all of the control-logic systems, and the suboptimality of the rest-to-rest maneuvers is proven for principal-axis rotations. The most efficient control technique is the singular control of infinite order, and the vector-valued singular control can be utilized in a derivative of the switching function.

  8. Motion of a spacecraft with magnetic damper

    Science.gov (United States)

    Roithmayr, Carlos M.; Hu, Anren; Chipman, Richard

    1992-01-01

    Three methods of numerically simulating the motion of a spacecraft with a magnetic damper are compared. Simulations of motion of the initial assembly stage of Space Station Freedom show that results obtained with the first approach are in general agreement with those based on the second approach, while results from the third method are incorrect unless the spacecraft is nearly at rest in a local-vertical-local-horizontal reference frame. Simulations based on the second method proceed much more quickly than simulations based on the first. An integral of equations of motion governing the behavior of a spacecraft, and a sphere, which is part of the damper is presented. The integral can be used to test the results of numerical integrations performed in connection with the first and second approaches.

  9. Developing Sustainable Spacecraft Water Management Systems

    Science.gov (United States)

    Thomas, Evan A.; Klaus, David M.

    2009-01-01

    It is well recognized that water handling systems used in a spacecraft are prone to failure caused by biofouling and mineral scaling, which can clog mechanical systems and degrade the performance of capillary-based technologies. Long duration spaceflight applications, such as extended stays at a Lunar Outpost or during a Mars transit mission, will increasingly benefit from hardware that is generally more robust and operationally sustainable overtime. This paper presents potential design and testing considerations for improving the reliability of water handling technologies for exploration spacecraft. Our application of interest is to devise a spacecraft wastewater management system wherein fouling can be accommodated by design attributes of the management hardware, rather than implementing some means of preventing its occurrence.

  10. Mars Science Laboratory Spacecraft Assembled for Testing

    Science.gov (United States)

    2008-01-01

    The major components of NASA's Mars Science Laboratory spacecraft cruise stage atop the aeroshell, which has the descent stage and rover inside were connected together in October 2008 for several weeks of system testing, including simulation of launch vibrations and deep-space environmental conditions. These components will be taken apart again, for further work on each of them, after the environmental testing. The Mars Science Laboratory spacecraft is being assembled and tested for launch in 2011. This image was taken inside the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory, Pasadena, Calif., which manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology.

  11. Spacecraft Station-Keeping Trajectory and Mission Design Tools

    Science.gov (United States)

    Chung, Min-Kun J.

    2009-01-01

    Two tools were developed for designing station-keeping trajectories and estimating delta-v requirements for designing missions to a small body such as a comet or asteroid. This innovation uses NPOPT, a non-sparse, general-purpose sequential quadratic programming (SQP) optimizer and the Two-Level Differential Corrector (T-LDC) in LTool (Libration point mission design Tool) to design three kinds of station-keeping scripts: vertical hovering, horizontal hovering, and orbiting. The T-LDC is used to differentially correct several trajectory legs that join hovering points. In a vertical hovering, the maximum and minimum range points must be connected smoothly while maintaining the spacecrafts range from a small body, all within the law of gravity and the solar radiation pressure. The same is true for a horizontal hover. A PatchPoint is an LTool class that denotes a space-time event with some extra information for differential correction, including a set of constraints to be satisfied by T-LDC. Given a set of PatchPoints, each with its own constraint, the T-LDC differentially corrects the entire trajectory by connecting each trajectory leg joined by PatchPoints while satisfying all specified constraints at the same time. Vertical and horizontal hover both are needed to minimize delta-v spent for station keeping. A Python I/F to NPOPT has been written to be used from an LTool script. In vertical hovering, the spacecraft stays along the line joining the Sun and a small body. An instantaneous delta-v toward the anti- Sun direction is applied at the closest approach to the small body for station keeping. For example, the spacecraft hovers between the minimum range (2 km) point and the maximum range (2.5 km) point from the asteroid 1989ML. Horizontal hovering buys more time for a spacecraft to recover if, for any reason, a planned thrust fails, by returning almost to the initial position after some time later via a near elliptical orbit around the small body. The mapping or

  12. The MSAT spacecraft of Telesat Mobile Inc.

    Science.gov (United States)

    Bertenyi, E.

    The MSAT spacecraft of the Canadian mobile satellite operator, Telesat Mobile Inc. (TMI) is described. When launched in 1994, the large geostationary MSAT spacecraft which is currently under construction by Hughes Aircraft Co. and Spar Aerospace Ltd. will enable TMI to provide mobile and transportable communications services to its customers even in the most remote parts of the North American continent. The main elements of TMI's mobile satellite system (described in a companion paper) are the space segment and the ground segment. TMI's space segment will employ one of two nearly identical satellites, one of which will be owned and operated by TMI, the other by the U.S. mobile satellite operator, American Mobile Satellite Corporation (AMSC). The two companies are participating in a joint spacecraft procurement in order to reduce the nonrecurring costs and to ensure system compatibility between the two systems; and they have also agreed to provide in-orbit backup to each other in the event of a catastrophic satellite failure. The program status, performance requirements, main parameters, and configuration of the MSAT spacecraft are reviewed. The major features of the communications subsystem are discussed in some detail, and a brief summary is presented of the spacecraft service module. Key technology items include the L-band RF power amplifier, which must operate with a high DC to RF power efficiency and generate low intermodulation when loaded with multi-carrier signals; and the large diameter deployable L-band antenna. The development status and expected performance of these spacecraft components is examined.

  13. Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

    Science.gov (United States)

    DeSimpelaere, Edward

    2011-01-01

    The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

  14. Spacecraft Internal Acoustic Environment Modeling

    Science.gov (United States)

    Chu, SShao-sheng R.; Allen, Christopher S.

    2009-01-01

    Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was

  15. Manned Spacecraft Landing and Recovery

    Science.gov (United States)

    Hammel, Don

    2004-01-01

    As recent history has tragically demonstrated, a successful space mission is not complete until the crew has safely returned to earth and has been successfully recovered. It is noted that a safe return to earth does not guarantee a successful recovery. The focus of this presentation will be a discussion of the ground operation assets involved in a successful recovery. The author's experience in land and water-based recovery of crewed vehicles and flight hardware at Kennedy Space Center (KSC), Edwards Air Force Base, international landing sites, and the Atlantic Ocean provides for some unique insight into this topic. He has participated in many aspects of Space Shuttle landing and recovery operations including activation of Transatlantic Abort Landing (TAL) sites and Emergency Landing Sites (ELS) as an Operations Test Director, execution of post landing convoy operations as an Orbiter Move Director, Operations Test Director, and Landing and Recovery Director, and recovery of solid rocket boosters, frustum and their parachutes 140 miles offshore in a wide range of sea states as a Retrieval Diver/Engineer. The recovery operations for the Mercury, Gemini, and Apollo were similar from a landing and recovery perspective in th t they all were capsules with limited "flying" capability and had a planned End of Mission (EOM) in an ocean with a descent slowed by parachutes. The general process was to deploy swim teams via helicopters to prepare the capsule for recovery and assist with crew extraction when required. The capsule was then hoisted onto the deck of a naval vessel. This approach required the extensive use and deployment of military assets to support the primary landing zone as well as alternate and contingency locations. The Russian Soyuz capsule also has limited "flying" capability; however, the planned EOM is terrestrial. In addition to use of parachutes to slow the reentry descent, soft-landing rockets on the bottom of the vehicle are employed to cushion the

  16. Modeling and simulation of spacecraft power systems

    Science.gov (United States)

    Lee, J. R.; Cho, B. H.; Kim, S. J.; Lee, F. C.

    1987-01-01

    EASY5 modeling of a complete spacecraft power processing system is presented. Component models are developed, and several system models including a solar array switching system, a partially-shunted solar array system and COBE system are simulated. The power system's modes of operation, such as shunt mode, battery-charge mode, and battery-discharge mode, are simulated for a complete orbit cycle.

  17. Spacecraft Charging Sensitivity to Material Properties

    Science.gov (United States)

    Minow, Joseph I.; Edwards, David L.

    2015-01-01

    Evaluating spacecraft charging behavior of a vehicle in the space environment requires knowledge of the material properties relevant to the charging process. Implementing surface and internal charging models requires a user to specify a number of material electrical properties including electrical resistivity parameters (dark and radiation induced), dielectric constant, secondary electron yields, photoemission yields, and breakdown strength in order to correctly evaluate the electric discharge threat posed by the increasing electric fields generated by the accumulating charge density. In addition, bulk material mass density and/or chemical composition must be known in order to analyze radiation shielding properties when evaluating internal charging. We will first describe the physics of spacecraft charging and show how uncertainties in material properties propagate through spacecraft charging algorithms to impact the results obtained from charging models. We then provide examples using spacecraft charging codes to demonstrate their sensitivity to material properties. The goal of this presentation is to emphasize the importance in having good information on relevant material properties in order to best characterize on orbit charging threats.

  18. Spacecraft potential control for Double Star

    Directory of Open Access Journals (Sweden)

    K. Torkar

    2005-11-01

    Full Text Available The spacecraft potential of Double Star TC-1 is positive in large parts of the orbits due to the photo-effect from solar EUV irradiation. These positive potentials typically disturb low energy plasma measurements on board. The potential can be reduced, and thereby the particle measurements improved, by emitting a positive ion beam. This method has successfully been applied on several other spacecraft and it has also been chosen for TC-1. The instrument TC-1/ASPOC is a derivative of the Cluster/ASPOC instruments, from which it has inherited many features. The paper describes the adaptations and further developments made for the ion emitters and the electronics. The instrument performs very well and can support higher beam currents than on Cluster. The expected significant improvement of the low energy particle measurements on board was indeed observed. The modifications of the electron distributions are analysed for a one-time interval when the spacecraft was located in the magnetosheath. The change in the potential due to the ion beam was determined, and first studies of the 3-D electron distributions in response to the spacecraft potential control have been performed, which indicate that the method works as expected.

  19. Standardization activity for the spacecraft onboard interfaces

    Science.gov (United States)

    Smith, J. F.; Plummer, C.; Plancke, P.

    2003-01-01

    The Consultative Committee for Space Data Systems (CCSDS) is an international organization of national space agencies that is organized to promote theinterchange of space related information. CCSDS is branching out to provide new standards to enhanced reuse of spacecraft equipment and software onboard of a spacecraft. This effort is know as Spacecraft Onboard Interface (SOIF). SOIF expects that these standards will be well used within the space community, and that they will be based on the well-known Internet protocols. This paper will provide a description of the SOIF work by reviewing this work with three orthogonal views. The Services View describes the data communications services that are provided to the users. The Interoperability view provides a description to users on how to use SOIF to interchange between different spacecraft data busses. And finally, the Protocol view, describes the protocols and services that are to be implemented in order to provide the users with the advantages of the SOIF architecture. This paper will give the reader an excellent introduction to the work of the international SOIF team.

  20. How Spacecraft Fly Spaceflight Without Formulae

    CERN Document Server

    Swinerd, Graham

    2009-01-01

    About half a century ago a small satellite, Sputnik 1, was launched. The satellite did very little other than to transmit a radio signal to announce its presence in orbit. However, this humble beginning heralded the dawn of the Space Age. Today literally thousands of robotic spacecraft have been launched, many of which have flown to far-flung regions of the Solar System carrying with them the human spirit of scientific discovery and exploration. Numerous other satellites have been launched in orbit around the Earth providing services that support our technological society on the ground. How Spacecraft Fly: Spaceflight Without Formulae by Graham Swinerd focuses on how these spacecraft work. The book opens with a historical perspective of how we have come to understand our Solar System and the Universe. It then progresses through orbital flight, rocket science, the hostile environment within which spacecraft operate, and how they are designed. The concluding chapters give a glimpse of what the 21st century may ...

  1. Integrated Thermal Insulation System for Spacecraft

    Science.gov (United States)

    Kolodziej, Paul (Inventor); Bull, Jeff (Inventor); Kowalski, Thomas (Inventor); Switzer, Matthew (Inventor)

    1998-01-01

    An integrated thermal protection system (TPS) for a spacecraft includes a grid that is bonded to skin of the spacecraft, e.g., to support the structural loads of the spacecraft. A plurality of thermally insulative, relatively large panels are positioned on the grid to cover the skin of the spacecraft to which the grid has been bonded. Each panel includes a rounded front edge and a front flange depending downwardly from the front edge. Also, each panel includes a rear edge formed with a rounded socket for receiving the rounded front edge of another panel therein, and a respective rear flange depends downwardly from each rear edge. Pins are formed on the front flanges, and pin receptacles are formed on the rear flanges, such that the pins of a panel mechanically interlock with the receptacles of the immediately forward panel. To reduce the transfer to the skin of heat which happens to leak through the panels to the grid, the grid includes stringers that are chair-shaped in cross-section.

  2. Spacecraft 3D Augmented Reality Mobile App

    Science.gov (United States)

    Hussey, Kevin J.; Doronila, Paul R.; Kumanchik, Brian E.; Chan, Evan G.; Ellison, Douglas J.; Boeck, Andrea; Moore, Justin M.

    2013-01-01

    The Spacecraft 3D application allows users to learn about and interact with iconic NASA missions in a new and immersive way using common mobile devices. Using Augmented Reality (AR) techniques to project 3D renditions of the mission spacecraft into real-world surroundings, users can interact with and learn about Curiosity, GRAIL, Cassini, and Voyager. Additional updates on future missions, animations, and information will be ongoing. Using a printed AR Target and camera on a mobile device, users can get up close with these robotic explorers, see how some move, and learn about these engineering feats, which are used to expand knowledge and understanding about space. The software receives input from the mobile device's camera to recognize the presence of an AR marker in the camera's field of view. It then displays a 3D rendition of the selected spacecraft in the user's physical surroundings, on the mobile device's screen, while it tracks the device's movement in relation to the physical position of the spacecraft's 3D image on the AR marker.

  3. Software for Engineering Simulations of a Spacecraft

    Science.gov (United States)

    Shireman, Kirk; McSwain, Gene; McCormick, Bernell; Fardelos, Panayiotis

    2005-01-01

    Spacecraft Engineering Simulation II (SES II) is a C-language computer program for simulating diverse aspects of operation of a spacecraft characterized by either three or six degrees of freedom. A functional model in SES can include a trajectory flight plan; a submodel of a flight computer running navigational and flight-control software; and submodels of the environment, the dynamics of the spacecraft, and sensor inputs and outputs. SES II features a modular, object-oriented programming style. SES II supports event-based simulations, which, in turn, create an easily adaptable simulation environment in which many different types of trajectories can be simulated by use of the same software. The simulation output consists largely of flight data. SES II can be used to perform optimization and Monte Carlo dispersion simulations. It can also be used to perform simulations for multiple spacecraft. In addition to its generic simulation capabilities, SES offers special capabilities for space-shuttle simulations: for this purpose, it incorporates submodels of the space-shuttle dynamics and a C-language version of the guidance, navigation, and control components of the space-shuttle flight software.

  4. Microgravity Flammability Experiments for Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Legros, Guillaume; Minster, Olivier; Tóth, Balazs

    2012-01-01

    As fire behaviour in manned spacecraft still remains poorly understood, an international topical team has been created to design a validation experiment that has an unprecedented large scale for a microgravity flammability experiment. While the validation experiment is being designed for a re-sup...

  5. Pathophysiological implications of the chemical messengers; Implicaciones fisiopatologicas de los mensajeros quimicos

    Energy Technology Data Exchange (ETDEWEB)

    Blazquez Fernandez, E.

    2009-07-01

    To maintain a physical organization and a different composition of its surroundings environment, living beings use a great part of the energy that they produce. Vital processes require an elevated number of reactions which are regulated and integrated by chemical messengers. They use autocrine, paracrine, endocrine and synaptic signals through receptors of cell surface, nuclear or associated with ionic channels, enzymes, trim eric G proteins and to intracellular kinases. Through these mechanisms pheromones play an important role in the relationships between different individuals, and hormones are able to regulate the integrative functions of our organism. In the nervous system, neurotransmitters, neuromodulators, sensors and receptors between other messengers, play functions of great relevance, while growth factors stimulate cell proliferation and cytokines have many effects but the most important is the ones related with the control of the immflamatory process. Alterations of these messengers permit us a better understanding of the diseases and possibly of its treatments in a near future. Modifications of the expression of genes from the nuclear and mitochondrial genomes are responsible of monogenic, polygenic and mitochondrial diseases, while alterations in the activities of dopamine and serotonin neurotransmitters are related with schizophrenia, Parkinson disease and depression, respectively. Other example is the hyperthyroidism of the Graves-Bassedow disease due to the competitive interference of the LATS immunoglobulin with TSH at the level of the follicular cells producing thyroid hormones Twenty five years ago in the reviews on the mechanisms of insulin action, there was presentations in which the insulin receptor was located in the plasma membrane of the target cells while in the cytoplasm only a big interrogative was observed, that at present is replaced by chemical mediators cascades responsible of the multiple effects of insulin. This finding is similar

  6. Messenger molecules of the phospholipase signaling system have dual effects on vascular smooth muscle contraction.

    Science.gov (United States)

    Vidulescu, Cristina; Mironneau, J.; Mironneau, Chantal; Popescu, L. M.

    2000-01-01

    Background and methods. In order to investigate the role of phospholipases and their immediately derived messengers in agonist-induced contraction of portal vein smooth muscle, we used the addition in the organ bath of exogenous molecules such as: phospholipases C, A(2), and D, diacylglycerol, arachidonic acid, phosphatidic acid, choline. We also used substances modulating activity of downstream molecules like protein kinase C, phosphatidic acid phosphohydrolase, or cyclooxygenase. Results. a) Exogenous phospholipases C or A(2), respectively, induced small agonist-like contractions, while exogenous phospholipase D did not. Moreover, phospholipase D inhibited spontaneous contractions. However, when added during noradrenaline-induced plateau, phospholipase D shortly potentiated it. b) The protein kinase C activator, phorbol dibutyrate potentiated both the exogenous phospholipase C-induced contraction and the noradrenaline-induced plateau, while the protein kinase C inhibitor 1-(-5-isoquinolinesulfonyl)-2-methyl-piperazine relaxed the plateau. c) When added before noradrenaline, indomethacin inhibited both phasic and tonic contractions, but when added during the tonic contraction shortly potentiated it. Arachidonic acid strongly potentiated both spontaneous and noradrenaline-induced contractions, irrespective of the moment of its addition. d) In contrast, phosphatidic acid inhibited spontaneous contractile activity, nevertheless it was occasionally capable of inducing small contractions, and when repetitively added during the agonist-induced tonic contraction, produced short potentiations of the plateau. Pretreatment with propranolol inhibited noradrenaline-induced contractions and further addition of phosphatidic acid augmented this inhibition. Choline augmented the duration and amplitude of noradrenaline-induced tonic contraction and final contractile oscillations. Conclusions. These data suggest that messengers produced by phospholipase C and phospholipase A(2

  7. Particle Tracing of Heavy Ions in Hermean Exosphere With Applications to the MESSENGER.

    Science.gov (United States)

    Paral, J.; Travnicek, P.; Rankin, R.; Kabin, K.

    2008-12-01

    We carry out Monte Carlo simulations of heavy particle species which are released from the surface of the planet Mercury as neutral particles and later on they are ionized. We consider three major sources of particle injection, namely Photon stimulated desorption, Solar wind sputtering and Micro-meteoroid vaporisation to build neutral exosphere. Then, we investigate the resulting exosphere and identify regions of particle acceleration due to the electromagnetic fields as well as distribution of ionization in the simulation box. The results are put into the context of the MESSENGER mission which measure the in situ data during its first fly by on January, 14 2008.

  8. Computer Self-Efficiency as an Antecedent to the Acceptance of Instant Messenger Technology

    OpenAIRE

    Thomas F. Stafford

    2005-01-01

    AOL Instant Messenger (IM) is a widely used Internet chat technology. There are indications that users initially do not find it easy to use, and this concerns AOL management; they consider that if popular applications are not easy to use, the ability of AOL to attract and hold loyal customers will be impeded. In this paper, the acceptance of IM technology is investigated within the familiar framework of the Technology Acceptance Model (TAM), in which ease of use plays a pivotal role in promot...

  9. High-throughput and quantitative genome-wide messenger RNA sequencing for molecular phenotyping.

    Science.gov (United States)

    Collins, John E; Wali, Neha; Sealy, Ian M; Morris, James A; White, Richard J; Leonard, Steven R; Jackson, David K; Jones, Matthew C; Smerdon, Nathalie C; Zamora, Jorge; Dooley, Christopher M; Carruthers, Samantha N; Barrett, Jeffrey C; Stemple, Derek L; Busch-Nentwich, Elisabeth M

    2015-08-05

    We present a genome-wide messenger RNA (mRNA) sequencing technique that converts small amounts of RNA from many samples into molecular phenotypes. It encompasses all steps from sample preparation to sequence analysis and is applicable to baseline profiling or perturbation measurements. Multiplex sequencing of transcript 3' ends identifies differential transcript abundance independent of gene annotation. We show that increasing biological replicate number while maintaining the total amount of sequencing identifies more differentially abundant transcripts. This method can be implemented on polyadenylated RNA from any organism with an annotated reference genome and in any laboratory with access to Illumina sequencing.

  10. Regional distribution of glycine receptor messenger RNA in the central nervous system of zebrafish.

    Science.gov (United States)

    Imboden, M; Devignot, V; Korn, H; Goblet, C

    2001-01-01

    We report the cloning of the zebrafish beta subunit of the glycine receptor and compare the anatomical distribution of three glycine receptor subunit constituents in adult zebrafish brain (alphaZ1, alphaZ2 and betaZ) to the expression pattern of homologous receptor subunits (alpha1, alpha2 and beta) in the mammalian adult CNS. Non-radioactive hybridization was used to map the distribution of the alphaZ1, alphaZ2 and betaZ glycine receptor subunit messenger RNAs in the adult zebrafish brain. The anterior-posterior expression gradient found in adult zebrafish brain was similar to that reported in mammalian CNS. However, the glycine receptor transcripts, notably the alphaZ1 subunit, were more widely distributed in the anterior regions of the zebrafish than in the adult mammalian brain. The isoform-specific distribution pattern was less regionalized in zebrafish than in the rat mammalian CNS. Nevertheless, there was some regionalization of alphaZ1, alphaZ2 and betaZ transcripts in the diencephalic and mesencephalic nuclei where different sensory and motor centers express either alphaZ1/betaZ or alphaZ2 subunits. In contrast to the widespread distribution of the beta subunit in adult mammalian brain, alphaZ2 messenger RNA presented the widest expression territory of all three glycine receptor subunits tested. alphaZ2 messenger RNA was expressed in the absence of alphaZ1 and betaZ messenger RNA in the outer nuclear layer of the retina, the inferior olive and the raphe of the medulla oblongata, as well as in the nucleus of Cajal of the medulla spinalis. In contrast, an identified central neuron of the reticular formation, the Mauthner cell, expresses all three glycine receptor subunits (alphaZ1, alphaZ2 and betaZ). This report extends the already described glycine receptor expression in the vertebrate CNS and confirms the importance of glycine-mediated inhibition in spinal cord and brainstem.

  11. MESSENGER Observations of the Spatial Distribution of Planetary Ions Near Mercury

    Science.gov (United States)

    Zurbuchen, Thomas H.; Raines, Jim M.; Slavin, James A.; Gershman, Daniel J.; Gilbert, Jason A.; Gloeckler, George; Anderson, Brian J.; Baker, Daniel N.; Korth, Haje; Krimigis, Stamatios M.; hide

    2011-01-01

    Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na(+)) and oxygen (O(+)), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury's ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He(+)) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na(+) pressure can be a substantial fraction of the proton pressure.

  12. Mercury's Hollows: New Information on Distribution and Morphology from MESSENGER Observations at Low Altitude

    Science.gov (United States)

    Blewett, D. T.; Stadermann, A. C.; Chabot, N. L.; Denevi, B. W.; Ernst, C. M.; Peplowski, P. N.

    2014-12-01

    MESSENGER's orbital mission at Mercury led to the discovery of an unusual landform not known from other airless rocky bodies of the Solar System. Hollows are irregularly shaped, shallow, rimless depressions, often occurring in clusters and with high-reflectance interiors and halos. The fresh appearance of hollows suggests that they are relatively young features. For example, hollows are uncratered, and talus aprons downslope of hollows in certain cases appear to be covering small impact craters (100-200 in diameter). Hence, some hollows may be actively forming at present. The characteristics of hollows are suggestive of formation via destruction of a volatile-bearing phase (possibly one or more sulfides) through solar heating, micrometeoroid bombardment, and/or ion impact. Previous analysis showed that hollows are associated with low-reflectance material (LRM), a color unit identified from global color images. The material hosting hollows has often been excavated from depth by basin or crater impacts. Hollows are small features (tens of meters to several kilometers), so their detection and characterization with MESSENGER's global maps have been limited. MESSENGER's low-altitude orbits provide opportunities for collection of images at high spatial resolutions, which reveal new occurrences of hollows and offer views of hollows with unprecedented detail. As of this writing, we have examined more than 21,000 images with pixel sizes images. Locations of the hollows (e.g., crater floor, rim, central peak, plains) were recorded. Shadow-length measurements were made on 280 images, yielding the depths of 1343 individual hollows. The mean depth is 30 m, with a standard deviation of 17 m. We also explored correlations between the geographic locations of hollows and maps provided by the MESSENGER geochemical sensors (X-Ray, Gamma-Ray, and Neutron Spectrometers), including the abundances of Al/Si, Ca/Si, Fe/Si, K, Mg/Si, and S/Si, as well as total neutron cross-section. No

  13. Transfer-messenger RNA controls the translation of cell-cycle and stress proteins in Streptomyces

    DEFF Research Database (Denmark)

    Barends, Sharief; Zehl, Martin; Bialek, Sylwia

    2010-01-01

    The transfer-messenger RNA (tmRNA)-mediated trans-translation mechanism is highly conserved in bacteria and functions primarily as a system for the rescue of stalled ribosomes and the removal of aberrantly produced proteins. Here, we show that in the antibiotic-producing soil bacterium Streptomyc...... functionality for tmRNA, promoting the translation of the same mRNA it targets, at the expense of sacrificing the first nascent protein. In streptomycetes, tmRNA has evolved into a dedicated task force that ensures the instantaneous response to the exposure to stress....

  14. SPEECH ACTS PREFERENCE IN COMPUTER – MEDIATED INTERCULTURAL COMMUNICATION VIA FACEBOOK MESSENGER: A NETNOGRAPHIC STUDY

    OpenAIRE

    Nugraha, Yehezkiel Adhi

    2016-01-01

                People will not only use language for sharing message but also due to do an action. Through language, people will ask, promise, refuse, greet, invite, thank, and so on. The purpose of this research is to identify the speech acts preference used by Indonesian and Filipino non – native speakers of English via Facebook Messenger. Besides, to identify the similar or different of speech acts preference they used.             The source of data are utterances of conversation in Facebook...

  15. Synthesis of potentially caged sphingolipids, possible precursors of cellular modulators and second messengers.

    Science.gov (United States)

    Zehavi, U

    1997-11-19

    An increasing number of sphingolipids, glycosphingolipids and some of their degradation products have been recognized in recent years as second messengers involved in signal transduction and as modulators of numerous cellular functions. These can be converted into inert, caged compounds, introduced into cells and tissues and subsequently photolysed to active compounds thus enabling the study of fast biological processes. The novel, potentially caged compounds synthesized here are substituted 2-nitrobenzyl urethans and 2-nitrobenzyl amines derived from sphingosine, dihydrosphingosine, N-methylsphingosine, N-methyldihydrosphingosine, psychosine and glucosylsphingosine. Upon irradiation of the afore mentioned compounds they release, or are expected to release, the free biologically active amines.

  16. On the spacecraft attitude stabilization in the orbital frame

    Directory of Open Access Journals (Sweden)

    Antipov Kirill A.

    2012-01-01

    Full Text Available The paper deals with spacecraft in the circular near-Earth orbit. The spacecraft interacts with geomagnetic field by the moments of Lorentz and magnetic forces. The octupole approximation of the Earth’s magnetic field is accepted. The spacecraft electromagnetic parameters, namely the electrostatic charge moment of the first order and the eigen magnetic moment are the controlled quasiperiodic functions. The control algorithms for the spacecraft electromagnetic parameters, which allows to stabilize the spacecraft attitude position in the orbital frame are obtained. The stability of the spacecraft stabilized orientation is proved both analytically and by PC computations.

  17. Tropical Rainfall Measuring Mission (TRMM) project. VI - Spacecraft, scientific instruments, and launching rocket. Part 1 - Spacecraft

    Science.gov (United States)

    Keating, Thomas; Ihara, Toshio; Miida, Sumio

    1990-01-01

    A cooperative United States/Japan study was made for one year from 1987 to 1988 regarding the feasibility of the Tropical Rainfall Measuring Mission (TRMM). As part of this study a phase-A-level design of spacecraft for TRMM was developed by NASA/GSFC, and the result was documented in a feasibility study. The phase-A-level design is developed for the TRMM satellite utilizing a multimission spacecraft.

  18. Cold Helium Gas Pressurization For Spacecraft Cryogenic Propulsion Systems

    Science.gov (United States)

    Morehead, Robert L.; Atwell. Matthew J.; Hurlbert, Eric A.; Melcher, J. C.

    2017-01-01

    To reduce the dry mass of a spacecraft pressurization system, helium pressurant may be stored at low temperature and high pressure to increase mass in a given tank volume. Warming this gas through an engine heat exchanger prior to tank pressurization both increases the system efficiency and simplifies the designs of intermediate hardware such as regulators, valves, etc. since the gas is no longer cryogenic. If this type of cold helium pressurization system is used in conjunction with a cryogenic propellant, though, a loss in overall system efficiency can be expected due to heat transfer from the warm ullage gas to the cryogenic propellant which results in a specific volume loss for the pressurant, interpreted as the Collapse Factor. Future spacecraft with cryogenic propellants will likely have a cold helium system, with increasing collapse factor effects as vehicle sizes decrease. To determine the collapse factor effects and overall implementation strategies for a representative design point, a cold helium system was hotfire tested on the Integrated Cryogenic Propulsion Test Article (ICPTA) in a thermal vacuum environment at the NASA Glenn Research Center Plum Brook Station. The ICPTA vehicle is a small lander-sized spacecraft prototype built at NASA Johnson Space Center utilizing cryogenic liquid oxygen/liquid methane propellants and cryogenic helium gas as a pressurant to operate one 2,800lbf 5:1 throttling main engine, two 28lbf Reaction Control Engines (RCE), and two 7lbf RCEs (Figure 1). This vehicle was hotfire tested at a variety of environmental conditions at NASA Plum Brook, ranging from ambient temperature/simulated high altitude, deep thermal/high altitude, and deep thermal/high vacuum conditions. A detailed summary of the vehicle design and testing campaign may be found in Integrated Cryogenic Propulsion Test Article Thermal Vacuum Hotfire Testing, AIAA JPC 2017.

  19. Time Domain Astronomy with Fermi GBM in the Multi-messenger Era

    Science.gov (United States)

    Wilson-Hodge, Colleen A.; Fermi GBM team, GBM-LIGO team

    2018-01-01

    As the Multi-Messenger era begins with detections of gravitational waves with LIGO/Virgo and neutrinos with IceCube, the Fermi Gamma-ray Burst Monitor (GBM) provides context observations of gamma-ray transients between 8 keV and 40 MeV. Fermi GBM has a wide field of view, high uptime, and both in-orbit triggering and high time resolution continuous data enabling offline searches for weaker transients. GBM detects numerous gamma-ray bursts (GRBs), soft gamma-ray repeaters, X-ray bursters, solar flares and terrestrial gamma-ray flashes. Longer timescale transients, predominantly in our galaxy so far, are detected using the Earth occultation technique and epoch-folding for periodic sources. The GBM team has developed two ground-based searches to enhance detections of faint transients, especially short GRBs. The targeted search uses the time and location of an event detected with another instrument to coherently search the GBM data, increasing the sensitivity to a transient. The untargeted search agnostically searches the GBM data for all directions and times to find weaker transients. This search finds about 80 short GRBs per year, adding to the 40 per year triggered on-orbit. With its large field of view, high duty cycle and increasingly sophisticated detection methods, Fermi GBM is expected to have a major role in the Multi-Messenger era.

  20. Active site structure and catalytic mechanism of phosphodiesterase for degradation of intracellular second messengers

    Science.gov (United States)

    Zhan, Chang-Guo

    2002-03-01

    Phosphodiesterases are clinical targets for a variety of biological disorders, because this superfamily of enzymes regulate intracellular concentration of cyclic nucleotides that serve as the second messengers playing a critical role in a variety of physiological processes. Understanding structure and mechanism of a phosphodiesterase will provide a solid basis for rational design of the more efficient therapeutics. Although a three-dimensional X-ray crystal structure of the catalytic domain of human phosphodiesterase 4B2B was recently reported, it was uncertain whether a critical bridging ligand in the active site is a water molecule or a hydroxide ion. The identity of this bridging ligand has been determined by performing first-principles quantum chemical calculations on models of the active site. All the results obtained indicate that this critical bridging ligand in the active site of the reported X-ray crystal structure is a hydroxide ion, rather than a water molecule, expected to serve as the nucleophile to initialize the catalytic degradation of the intracellular second messengers.

  1. Expression of P450c17 messenger ribonucleic acid in postmenopausal human ovary tissues.

    Science.gov (United States)

    José, M; Puche, C; Cabero, A; Cabero, L; Meseguer, A

    1999-03-01

    To investigate the expression of the P450c17 gene in postmenopausal human ovaries compared with normal cycling ovaries. Prospective nonrandomized clinical research study. Servei de Medicina Reproductiva and Centre d'Investigacions en Bioquimica i Biologia Molecular, Hospitals Vall d'Hebron, Barcelona, Spain. Six premenopausal women and four postmenopausal women undergoing bilateral oophorectomy for nonovarian gynecologic disease. Extraction of 10 mL of peripheral venous blood for hormone measurements. Extraction of RNA from surgically removed ovaries for Northern blot, ribonuclease protection, and reverse transcriptase polymerase chain reaction Southern blot assays. Definition of the reproductive cycle state of each patient and determination of the level of P450c17 gene expression in all samples with the use of the semiquantitative reverse transcriptase polymerase chain reaction Southern blot assay. P450c17 messenger RNA levels in postmenopausal ovaries varied considerably between samples. Although the levels were similar to those detected in the early follicular phase, one of the samples had levels as high as those observed in the late follicular phase. Although the degree varied from one sample to another, all the postmenopausal ovaries studied expressed the P450c17 gene at the messenger RNA level. In a sample from a patient with endometrial adenocarcinoma, the level was as high as the levels observed in the late follicular phase.

  2. A novel frameshift mutation in the lipoprotein lipase gene is rescued by alternative messenger RNA splicing.

    Science.gov (United States)

    Laurie, Andrew D; Kyle, Campbell V

    Type I hyperlipoproteinemia, manifesting as chylomicronemia and severe hypertriglyceridemia, is a rare autosomal recessive disorder usually caused by mutations in the lipoprotein lipase gene (LPL). We sought to determine whether mutations in LPL could explain the clinical indications of a patient presenting with pancreatitis and hypertriglyceridemia. Coding regions of LPL were amplified by polymerase chain reaction and analyzed by nucleotide sequencing. The LPL messenger RNA transcript was also analyzed to investigate whether alternative splicing was occurring. The patient was homozygous for the mutation c.767_768insTAAATATT in exon 5 of the LPL gene. This mutation is predicted to result in either a truncated nonfunctional LPL, or alternatively a new 5' donor splice site may be used, resulting in a full-length LPL with an in-frame deletion of 3 amino acids. Analysis of messenger RNA from the patient showed that the new splice site is used in vivo. Homozygosity for a mutation in the LPL gene was consistent with the clinical findings. Use of the new splice site created by the insertion mutation rescues an otherwise damaging frameshift mutation, resulting in expression of an almost full-length LPL that is predicted to be partially functional. The patient therefore has a less severe form of type I hyperlipoproteinemia than would be expected if she lacked any functional LPL. Copyright © 2017 National Lipid Association. Published by Elsevier Inc. All rights reserved.

  3. Time Domain Astronomy with Fermi GBM in the Multi-messenger Era

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2017-08-01

    As the Multi-Messenger era begins with detections of gravitational waves with LIGO and neutrinos with IceCube, the Fermi Gamma-ray Burst Monitor provides context observations of gamma-ray transients between 8 keV and 40 MeV. Fermi GBM has a wide field of view, high uptime, and both in-orbit triggering and high time resolution continuous data enabling offline searches for weaker transients. GBM detects numerous gamma-ray bursts (GRBs), soft gamma-ray repeaters, X-ray bursters, solar flares and terrestrial gamma-ray flashes. Longer timescale transients, predominantly in our galaxy so far, are detected using the Earth occultation technique and epoch-folding for periodic sources. The GBM team has developed two ground-based searches to enhance detections of faint transients, especially short GRBs. The targeted search uses the time and location of an event detected with another instrument to coherently search the GBM data, increasing the sensitivity to a transient. The untargeted search agnostically searches the GBM data for all directions and times to find weaker transients. This search finds about 80 short GRBs per year, in addition to the 40 per year triggered on-orbit. With its large field of view, high duty cycle and increasingly sophisticated detection methods, Fermi GBM is expected to have a major role in the Multi-Messenger era.

  4. High-Performance Fire Detector for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The danger from fire aboard spacecraft is immediate with only moments for detection and suppression. Spacecraft are unique high-value systems where the cost of...

  5. Nanocomposites in Multifuntional Structures for Spacecraft Platforms

    Science.gov (United States)

    Marcos, J.; Mendizabal, M.; Elizetxea, C.; Florez, S.; Atxaga, G.; Del Olmo, E.

    2012-07-01

    The integration of functionalities as electrical, thermal, power or radiation shielding inside carrier electronic boxes, solar panels or platform structures allows reducing weight, volume, and harness for spacecraft. The multifunctional structures represent an advanced design approach for space components and subsystems. The development of such multifunctional structures aims the re-engineering traditional metallic structures by composites in space, which request to provide specific solutions for thermal conductivity, EMI-EMC, radiation shielding and integration. The use of nanomaterials as CNF and nano-adds to reinforce composite structures allows obtaining local solutions for improving electrical conductivity, thermal conductivity and radiation shielding. The paper summarises the results obtained in of three investigations conducted by Tecnalia based on carbon nanofillers for improving electro-thermal characteristics of spacecraft platform, electronic substrates and electronics boxes respectively.

  6. Microgravity Flammability Experiments for Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Legros, Guillaume; Minster, Olivier; Tóth, Balazs

    2012-01-01

    spread, and thus also the modeling thereof, in realistic conditions is described. Some of the parameters governing the flame spread are also identified and their scaling against the dimensions of the test specimen is briefly questioned. Then several of the current and scheduled efforts are presented......-supply vehicle like the ATV or Orbital’s Cygnus, a series of supporting experiments are being planned and conducted by the team members. In order to answer the appropriate scientific and engineering problems relevant for spacecraft fire safety, a canonical scenario that can improve the understanding of flame...... in terms of their relevance for the flame spread problem. Further, it is explained how the results can be combined to enhance the understanding of fire spread in the real scale configuration and thus improve the fire safety onboard spacecrafts. The results and particularly the ones from the large scale...

  7. Low noise spacecraft attitude control systems

    Science.gov (United States)

    Gondhalekar, Vijay; Downer, James R.; Eisenhaure, David B.; Hockney, Richard L.; Johnson, Bruce G.

    1991-01-01

    The authors describe two ongoing research efforts directed at developing advanced spacecraft momentum control flywheels. The first effort is directed at developing low-noise momentum wheels through the use of magnetic bearings. The second effort is directed at demonstrating critical subcomponents of an integrated power and attitude control system (IPACS) that stores energy as kinetic energy in mechanical rotors with the accompanying angular momentum available for attitude control of the spacecraft. The authors describe a ground experiment that was designed to demonstrate an energy storage capability of 1 kWh at a 40 Wh/kg energy density and a 1 kW electrical generation capacity at 85 percent round-trip efficiency and that will allow single-degree-of-freedom gimballing to quantify experimentally the bearing power requirements for processing the flywheel.

  8. Technology Needs for Air Force Autonomous Spacecraft

    Science.gov (United States)

    1982-03-16

    Jet Propulsion Laboratory’s (JPL) Autonomous Spacecraft Project (ASP). Accession For IT " .. . cation ;; 4b Dist-4 ! Aion / Avn ’l!ity Codes .,iml and/or...technologies in different major headings cannot be made. INDEX C.1 System Design, Programming, and Validation Technology C.1.1 Autonomy Methodology C.1.2...interfacou, raduw.LAncy and programming. There are some configurations which are both centralized and distributed and therefore have different characteristics

  9. Spacecraft Attitude Control in Hamiltonian Framework

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    is the sum of the gradient of the potential energy and the dissipative force. It is shown that this control law makes the system uniformly asymptotically stable to the desired reference point. Three problems were addressed in the paper: spacecraft stabilization in the inertial frame, libration damping...... with the use of electromagnetic coils and a slew maneuver with an additional objective of avoiding undesirable regions e.g. causing blindness of optical sensors...

  10. THE FUTURE OF SPACECRAFT NUCLEAR PROPULSION

    OpenAIRE

    Jansen, Frank

    2014-01-01

    This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

  11. The Future of Spacecraft Nuclear Propulsion

    Science.gov (United States)

    Jansen, F.

    2014-06-01

    This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

  12. Schema for Spacecraft-Command Dictionary

    Science.gov (United States)

    Laubach, Sharon; Garcia, Celina; Maxwell, Scott; Wright, Jesse

    2008-01-01

    An Extensible Markup Language (XML) schema was developed as a means of defining and describing a structure for capturing spacecraft command- definition and tracking information in a single location in a form readable by both engineers and software used to generate software for flight and ground systems. A structure defined within this schema is then used as the basis for creating an XML file that contains command definitions.

  13. Building the Small Spacecraft Technology Pipeline

    OpenAIRE

    Reuther, Dr. James

    2011-01-01

    Biography - Dr. Reuther currently serves as the Acting Director for Crosscutting Capability Demonstrations in the Office of Chief Technologist of the National Aeronautics and Space Administration (NASA) Headquarters. Previously, Dr. Reuther served as the Lead of the Test and Verification (T&V) Office for the Orion spacecraft development. After graduating from the University of California Davis with a Bachelors, Masters, and Ph.D. in mechanical and aeronautical engineering, Dr. Reuther perform...

  14. Additive Manufacturing: Ensuring Quality for Spacecraft Applications

    Science.gov (United States)

    Swanson, Theodore; Stephenson, Timothy

    2014-01-01

    Reliable manufacturing requires that material properties and fabrication processes be well defined in order to insure that the manufactured parts meet specified requirements. While this issue is now relatively straightforward for traditional processes such as subtractive manufacturing and injection molding, this capability is still evolving for AM products. Hence, one of the principal challenges within AM is in qualifying and verifying source material properties and process control. This issue is particularly critical for applications in harsh environments and demanding applications, such as spacecraft.

  15. Experiments On Transparent Conductive Films For Spacecraft

    Science.gov (United States)

    Perez-Davis, Marla E.; Rutledge, Sharon K.; De Groh, Kim K.; Hung, Ching-Cheh; Malave-Sanabria, Tania; Hambourger, Paul; Roig, David

    1995-01-01

    Report describes experiments on thin, transparent, electrically conductive films made, variously, of indium tin oxide covered by magnesium fluoride (ITO/MgF2), aluminum-doped zinc oxide (AZO), or pure zinc oxide (ZnO). Films are candidates for application to such spacecraft components, including various optoelectronic devices and window surfaces that must be protected against buildup of static electric charge. On Earth, such films useful on heat mirrors, optoelectronic devices, gas sensors, and automotive and aircraft windows.

  16. Artificial Intelligence and Spacecraft Power Systems

    Science.gov (United States)

    Dugel-Whitehead, Norma R.

    1997-01-01

    This talk will present the work which has been done at NASA Marshall Space Flight Center involving the use of Artificial Intelligence to control the power system in a spacecraft. The presentation will include a brief history of power system automation, and some basic definitions of the types of artificial intelligence which have been investigated at MSFC for power system automation. A video tape of one of our autonomous power systems using co-operating expert systems, and advanced hardware will be presented.

  17. Optimal autonomous spacecraft resiliency maneuvers using metaheuristics

    Science.gov (United States)

    Showalter, Daniel J.

    The growing congestion in space has increased the need for spacecraft to develop resilience capabilities in response to natural and man-made hazards. Equipping satellites with increased maneuvering capability has the potential to enhance resilience by altering their arrival conditions as they enter potentially hazardous regions. The propellant expenditure corresponding to increased maneuverability requires these maneuvers be optimized to minimize fuel expenditure and to the extent which resiliency can be preserved. This research introduces maneuvers to enhance resiliency and investigates the viability of metaheuristics to enable their autonomous optimization. Techniques are developed to optimize impulsive and continuous-thrust resiliency maneuvers. The results demonstrate that impulsive and low-thrust resiliency maneuvers require only meters per second of delta-velocity. Additionally, bi-level evolutionary algorithms are explored in the optimization of resiliency maneuvers which require a maneuvering spacecraft to perform an inspection of one of several target satellites while en-route to geostationary orbit. The methods developed are shown to consistently produce optimal and near-optimal results for the problems investigated and can be applied to future classes of resiliency maneuvers yet to be defined. Results indicate that the inspection requires an increase of only five percent of the propellant needed to transfer from low Earth orbit to geostationary orbit. The maneuvers and optimization techniques developed throughout this dissertation demonstrate the viability of the autonomous optimization of spacecraft resiliency maneuvers and can be utilized to optimize future classes of resiliency maneuvers.

  18. Probing interferometric parallax with interplanetary spacecraft

    Science.gov (United States)

    Rodeghiero, G.; Gini, F.; Marchili, N.; Jain, P.; Ralston, J. P.; Dallacasa, D.; Naletto, G.; Possenti, A.; Barbieri, C.; Franceschini, A.; Zampieri, L.

    2017-07-01

    We describe an experimental scenario for testing a novel method to measure distance and proper motion of astronomical sources. The method is based on multi-epoch observations of amplitude or intensity correlations between separate receiving systems. This technique is called Interferometric Parallax, and efficiently exploits phase information that has traditionally been overlooked. The test case we discuss combines amplitude correlations of signals from deep space interplanetary spacecraft with those from distant galactic and extragalactic radio sources with the goal of estimating the interplanetary spacecraft distance. Interferometric parallax relies on the detection of wavefront curvature effects in signals collected by pairs of separate receiving systems. The method shows promising potentialities over current techniques when the target is unresolved from the background reference sources. Developments in this field might lead to the construction of an independent, geometrical cosmic distance ladder using a dedicated project and future generation instruments. We present a conceptual overview supported by numerical estimates of its performances applied to a spacecraft orbiting the Solar System. Simulations support the feasibility of measurements with a simple and time-saving observational scheme using current facilities.

  19. Space Weathering Experiments on Spacecraft Materials

    Science.gov (United States)

    Engelhart, D. P.; Cooper, R.; Cowardin, H.; Maxwell, J.; Plis, E.; Ferguson, D.; Barton, D.; Schiefer, S.; Hoffmann, R.

    2017-01-01

    A project to investigate space environment effects on specific materials with interest to remote sensing was initiated in 2016. The goal of the project is to better characterize changes in the optical properties of polymers found in multi-layered spacecraft insulation (MLI) induced by electron bombardment. Previous analysis shows that chemical bonds break and potentially reform when exposed to high energy electrons like those seen in orbit. These chemical changes have been shown to alter a material's optical reflectance, among other material properties. This paper presents the initial experimental results of MLI materials exposed to various fluences of high energy electrons, designed to simulate a portion of the geosynchronous Earth orbit (GEO) space environment. It is shown that the spectral reflectance of some of the tested materials changes as a function of electron dose. These results provide an experimental benchmark for analysis of aging effects on satellite systems which can be used to improve remote sensing and space situational awareness. They also provide preliminary analysis on those materials that are most likely to comprise the high area-to-mass ratio (HAMR) population of space debris in the geosynchronous orbit environment. Finally, the results presented in this paper serve as a proof of concept for simulated environmental aging of spacecraft polymers that should lead to more experiments using a larger subset of spacecraft materials.

  20. Internet Distribution of Spacecraft Telemetry Data

    Science.gov (United States)

    Specht, Ted; Noble, David

    2006-01-01

    Remote Access Multi-mission Processing and Analysis Ground Environment (RAMPAGE) is a Java-language server computer program that enables near-real-time display of spacecraft telemetry data on any authorized client computer that has access to the Internet and is equipped with Web-browser software. In addition to providing a variety of displays of the latest available telemetry data, RAMPAGE can deliver notification of an alarm by electronic mail. Subscribers can then use RAMPAGE displays to determine the state of the spacecraft and formulate a response to the alarm, if necessary. A user can query spacecraft mission data in either binary or comma-separated-value format by use of a Web form or a Practical Extraction and Reporting Language (PERL) script to automate the query process. RAMPAGE runs on Linux and Solaris server computers in the Ground Data System (GDS) of NASA's Jet Propulsion Laboratory and includes components designed specifically to make it compatible with legacy GDS software. The client/server architecture of RAMPAGE and the use of the Java programming language make it possible to utilize a variety of competitive server and client computers, thereby also helping to minimize costs.

  1. Modeling Meteor Flares for Spacecraft Safety

    Science.gov (United States)

    Ehlert, Steven

    2017-01-01

    NASA's Meteoroid Environment Office (MEO) is tasked with assisting spacecraft operators and engineers in quantifying the threat the meteoroid environment poses to their individual missions. A more complete understanding of the meteoroid environment for this application requires extensive observations. One manner by which the MEO observes meteors is with dedicated video camera systems that operate nightly. Connecting the observational data from these video cameras to the relevant physical properties of the ablating meteoroids, however, is subject to sizable observational and theoretical uncertainties. Arguably the most troublesome theoretical uncertainty in ablation is a model for the structure of meteoroids, as observations clearly show behaviors wholly inconsistent with meteoroids being homogeneous spheres. Further complicating the interpretation of the observations in the context of spacecraft risk is the ubiquitous process of fragmentation and the flares it can produce, which greatly muddles any attempts to estimating initial meteoroid masses. In this talk a method of estimating the mass distribution of fragments in flaring meteors using high resolution video observations will be dis- cussed. Such measurements provide an important step in better understanding of the structure and fragmentation process of the parent meteoroids producing these flares, which in turn may lead to better constraints on meteoroid masses and reduced uncertainties in spacecraft risk.

  2. Delamination Assessment Tool for Spacecraft Composite Structures

    Science.gov (United States)

    Portela, Pedro; Preller, Fabian; Wittke, Henrik; Sinnema, Gerben; Camanho, Pedro; Turon, Albert

    2012-07-01

    Fortunately only few cases are known where failure of spacecraft structures due to undetected damage has resulted in a loss of spacecraft and launcher mission. However, several problems related to damage tolerance and in particular delamination of composite materials have been encountered during structure development of various ESA projects and qualification testing. To avoid such costly failures during development, launch or service of spacecraft, launcher and reusable launch vehicles structures a comprehensive damage tolerance verification approach is needed. In 2009, the European Space Agency (ESA) initiated an activity called “Delamination Assessment Tool” which is led by the Portuguese company HPS Lda and includes academic and industrial partners. The goal of this study is the development of a comprehensive damage tolerance verification approach for launcher and reusable launch vehicles (RLV) structures, addressing analytical and numerical methodologies, material-, subcomponent- and component testing, as well as non-destructive inspection. The study includes a comprehensive review of current industrial damage tolerance practice resulting from ECSS and NASA standards, the development of new Best Practice Guidelines for analysis, test and inspection methods and the validation of these with a real industrial case study. The paper describes the main findings of this activity so far and presents a first iteration of a Damage Tolerance Verification Approach, which includes the introduction of novel analytical and numerical tools at an industrial level. This new approach is being put to the test using real industrial case studies provided by the industrial partners, MT Aerospace, RUAG Space and INVENT GmbH

  3. Spacecraft charging requirements and engineering issues

    Science.gov (United States)

    Garrett, Henry B.; Whittlesey, Albert C.

    2006-01-01

    An effort is currently underway to recast and combine two NASA guidelines for mitigating the effects of spacecraft charging and electrostatic discharge on spacecraft. The task has the goal of taking the existing NASA guidelines for preventing surface electrostatic charging, NASA-TP-2361 (Purvis et al., 1984), and internal electrostatic charging, NASAHDBK 4002 (Whittlesey, 1999), and bringing them up to date with recent laboratory and onorbit findings. This paper will describe the status of those on-going efforts to combine and update the two guidelines. Reasons for the upgrades will be presented, including new subject material for which there is now a greater understanding or a greater need which changes satellite design procedures, or both. There will be an emphasis on the proposed contents and on the differences and similarities between surface and internal charging mitigation techniques. In addition, the mitigation requirements that can be derived from the combined handbook will be discussed with emphasis on how they might affect the engineering design and testing of future spacecraft.

  4. Follow-up of GW150914 and multi-messenger studies of transient astrophysical sources with the ANTARES neutrino telescope

    Directory of Open Access Journals (Sweden)

    Coleiro Alexis

    2017-01-01

    Full Text Available By constantly monitoring at least one complete hemisphere of the sky, neutrino telescopes are well designed to detect neutrinos emitted by transient astrophysical sources. In particular, the ANTARES telescope is currently the largest high-energy neutrino detector in the Northern Hemisphere. Searches for ANTARES neutrino candidates coincident with multi-wavelength and multi-messenger transient phenomena are performed by triggering optical, X-ray and radio observations immediately after the detection of an interesting ANTARES event and also by looking for neutrino emission spatially and temporally coincident with transient astrophysical events detected across the electromagnetic spectrum or with new messengers as gravitational-wave signals. The latest results of the multi-messenger analyses performed with ANTARES will be presented in this contribution. In particular, we will focus on the neutrino follow-up performed after the detection of the first gravitation-wave event, GW150914.

  5. Wireless Communication onboard Spacecraft : Draadloze Communicatie aan boord van Ruimtevaartuigen

    NARCIS (Netherlands)

    Amini, R.

    2016-01-01

    This dissertation focuses on intra-spacecraft wireless communication as a solution for reducing the spacecraft onboard harness. Despite outstanding advances in aerospace industry, the cost of accessing space is still very high and the amount of engineering work required for spacecraft design and

  6. Illustration of relative sizes of Mercury, Gemini and Apollo spacecraft

    Science.gov (United States)

    1987-01-01

    Artist concept illustrating the relative sizes of the one-man Mercury spacecraft, the two-man Gemini spacecraft, and the three-man Apollo spacecraft. Also shows line drawing of launch vehichles to show their relative size in relation to each other.

  7. Wireless Intra-Spacecraft Communication: The Benefits and the Challenges

    Science.gov (United States)

    Zheng, Will H.; Armstrong, John T.

    2010-01-01

    In this paper we present a systematic study of how intra-spacecraft wireless communication can be adopted to various subsystems of the spacecraft including C&DH (Command & Data Handling), Telecom, Power, Propulsion, and Payloads, and the interconnects between them. We discuss the advantages of intra-spacecraft wireless communication and the disadvantages and challenges and a proposal to address them.

  8. Interplanetary plasma scintillation parameters measurements retrieved from the spacecraft observations.

    Science.gov (United States)

    Molera Calvés, Guifré; Pogrebenko, S. V.; Wagner, J.; Maccaferri, G.; Colucci, G.; Kronschnabl, G.; Scilliro, F.; Bianco, G.; Pérez Ayúcar, M.; Cosmovici, C. B.

    2010-05-01

    Measurement of the Interplanetary Scintillations (IPS) of radio signals propagating through the plasma in the Solar System by the radio astronomical instruments is a powerful tool to characterise and study the spatial and temporal variation of the electron density in the Solar wind. Several techniques based on the observation of natural and artificial radio sources have been developed during the last 50 years. Here we report our results of the IPS parameters measurement based on the multi-station observations of the planetary mission spacecraft. The ESA Venus Express spacecraft was observed at X-band (8.4 GHz) by several European VLBI stations - Metsähovi Radio Observatory (Aalto University , FI), Medicina (INAF-RA, IT), Matera (ASI, IT), Wettzell (BKG, DE), Noto (INAF-IRA, IT) and Yebes (OAN-IGN, ES) during a 2008-2010 campaign in a framework of the PRIDE (Planetary Radio Interferometry and Doppler Experiments) project as a preparatory stage for the European Radio Astronomy VLBI facilities participation in the planned ESA planetary missions (EJSM, TESM, EVE and others). Observational data were processed at Metsähovi Radio Observatory with the on-purpose developed high performance, ultra-high spectral resolution and spacecraft tracking capable software spectrometer-correlator and analysed at the Joint Institute for VLBI in Europe (JIVE, NL). High quality of acquired and analysed data enables us to study and define several parameters of the S/C signal and accompanying "ranging" tones with milli-Hz accuracy, among which the phase fluctuations of the spacecraft signal carrier line can be used to characterise the interplanetary plasma density fluctuations along the signal propagation line at different spatial and temporal scales at different Solar elongations and which exhibits a near-Kolmogorov spectrum. Such essential parameters as the phase scintillation index and bandwidth of scintillations and their dependence on the solar elongation, distance to the target

  9. Protecting Spacecraft Fragments from Exposure to Small Debris

    Directory of Open Access Journals (Sweden)

    V. V. Zelentsov

    2015-01-01

    Full Text Available Since the launch of the first artificial Earth satellite a large amount of space debris has been accumulated in near-earth space. This debris comprises the exhausted spacecrafts, final stages of rocket-carriers and boosters, technological space junk, consisting of the structure elements, which are separated when deploying the solar arrays, antennas etc., as well as when undocking a booster and a spacecraft. All the debris is divided into observable one of over 100 mm in size and unobservable debris. In case of possible collision with the observed debris an avoidance manoeuvre is provided. The situation with unobservable debris is worse, its dimensions ranging from 100 mm to several microns. This debris is formed as a result of explosions of dead space objects and at collisions of destroyed spacecraft fragments against each other. This debris moves along arbitrary trajectories at different speeds.At collision of a spacecraft with fragments of small-size space debris, various consequences are possible: the device can immediately fail, suffer damages, which will have effect later and damages, which break no bones to the aircraft. Anyway, the spacecraft collision with small-size debris particles is undesirable. The protective shields are used to protect the aircraft from damage. Development of shield construction is complicated because the high cost of launch makes it impossible to conduct field tests of shields in space. All the work is carried out in the laboratory, with particles having co-impact speeds up to 10 km/s (possible speeds are up to 20 km/s and spherically shaped particles of 0.8 ... 3 mm in diameter.Various materials are used to manufacture shields. These are aluminum sheet, sandwich panels, metal mesh, metal foam, and woven materials (ballistic fabric. The paper considers single-layer (from sheet metal sandwich materials and multilayer shield designs. As experimental studies show, a single-layer shield protects colliding at speeds

  10. Thermal design of spacecraft solar arrays using a polyimide foam

    Science.gov (United States)

    Bianco, N.; Iasiello, M.; Naso, V.

    2015-11-01

    The design of the Thermal Control System (TCS) of spacecraft solar arrays plays a fundamental role. Indeed, the spacecraft components must operate within a certain range of temperature. If this doesn't occur, their performance is reduced and they may even break. Solar arrays, which are employed to recharge batteries, are directly exposed to the solar heat flux, and they need to be insulated from the earth's surface irradiation. Insulation is currently provided either with a white paint coating or with a Multi Layer Insulation (MLI) system [1]. A configuration based on an open-cell polyimide foam has also been recently proposed [2]. Using polyimide foams in TCSs looks very attractive in terms of costs, weight and assembling. An innovative thermal analysis of the above cited TCS configurations is carried out in this paper, by solving the porous media energy equation, under the assumption of Local Thermal Equilibrium (LTE) between the two phases. Radiation effects through the solar array are also considered by using the Rosseland approximation. Under a stationary daylight condition, temperature profiles are obtained by means of the finite-element based code COMSOL Multiphysics®. Finally, since the weight plays an important role in aerospace applications, weights of the three TCS configurations are compared.

  11. Testing and Optimization of Electrically Conductive Spacecraft Coatings

    Science.gov (United States)

    Mell, R. J.; Wertz, G. E.; Edwards, D. L. (Technical Monitor)

    2001-01-01

    This is the final report discussing the work done for the Space Environments and Effects (SEE) Program. It discusses test chamber design, coating research, and test results on electrically thermal control coatings. These thermal control coatings are being developed to have several orders of magnitude higher electrical conductivity than most available thermal control coatings. Most current coatings tend to have a range in surface resistivity from 1,011 to 1,013 ohms/sq. Historically, spacecraft have had thermal control surfaces composed of dielectric materials of either polymers (paints and metalized films) or glasses (ceramic paints and optical solar reflectors). Very seldom has the thermal control surface of a spacecraft been a metal where the surface would be intrinsically electrically conductive. The poor thermal optical properties of most metals have, in most cases, stopped them from being used as a thermal control surface. Metals low infrared emittance (generally considered poor for thermal control surfaces) and/or solar absorptance, have resulted in the use of various dielectric coatings or films being applied over the substrate materials in order to obtain the required optical properties.

  12. First Results of Venus Express Spacecraft Observations with Wettzell

    Science.gov (United States)

    Calves, Guifre Molera; Wagner, Jan; Neidhardt, Alexander; Kronschnabl, Gerhard; Ayucar, Miguel Perez; Cimo, Giuseppe; Pogrebenko, Sergei

    2010-01-01

    The ESA Venus Express spacecraft was observed at X-band with the Wettzell radio telescope in October-December 2009 in the framework of an assessment study of the possible contribution of the European VLBI Network to the upcoming ESA deep space missions. A major goal of these observations was to develop and test the scheduling, data capture, transfer, processing, and analysis pipeline. Recorded data were transferred from Wettzell to Metsahovi for processing, and the processed data were sent from Mets ahovi to JIVE for analysis. A turnover time of 24 hours from observations to analysis results was achieved. The high dynamic range of the detections allowed us to achieve a milliHz level of spectral resolution accuracy and to extract the phase of the spacecraft signal carrier line. Several physical parameters can be determined from these observational results with more observational data collected. Among other important results, the measured phase fluctuations of the carrier line at different time scales can be used to determine the influence of the solar wind plasma density fluctuations on the accuracy of the astrometric VLBI observations.

  13. Space Environments and Spacecraft Effects Organization Concept

    Science.gov (United States)

    Edwards, David L.; Burns, Howard D.; Miller, Sharon K.; Porter, Ron; Schneider, Todd A.; Spann, James F.; Xapsos, Michael

    2012-01-01

    The National Aeronautics and Space Administration (NASA) is embarking on a course to expand human presence beyond Low Earth Orbit (LEO) while also expanding its mission to explore the solar system. Destinations such as Near Earth Asteroids (NEA), Mars and its moons, and the outer planets are but a few of the mission targets. Each new destination presents an opportunity to increase our knowledge of the solar system and the unique environments for each mission target. NASA has multiple technical and science discipline areas specializing in specific space environments disciplines that will help serve to enable these missions. To complement these existing discipline areas, a concept is presented focusing on the development of a space environments and spacecraft effects (SENSE) organization. This SENSE organization includes disciplines such as space climate, space weather, natural and induced space environments, effects on spacecraft materials and systems and the transition of research information into application. This space environment and spacecraft effects organization will be composed of Technical Working Groups (TWG). These technical working groups will survey customers and users, generate products, and provide knowledge supporting four functional areas: design environments, engineering effects, operational support, and programmatic support. The four functional areas align with phases in the program mission lifecycle and are briefly described below. Design environments are used primarily in the mission concept and design phases of a program. Engineering effects focuses on the material, component, sub-system and system-level selection and the testing to verify design and operational performance. Operational support provides products based on real time or near real time space weather to mission operators to aid in real time and near-term decision-making. The programmatic support function maintains an interface with the numerous programs within NASA, other federal

  14. Regulation of Ras exchange factors and cellular localization of Ras activation by lipid messengers in T cells

    Directory of Open Access Journals (Sweden)

    Jesse E. Jun

    2013-09-01

    Full Text Available The Ras-MAPK signaling pathway is highly conserved throughout evolution and is activated downstream of a wide range of receptor stimuli. Ras guanine nucleotide exchange factors (RasGEFs catalyze GTP loading of Ras and play a pivotal role in regulating receptor-ligand induced Ras activity. In T cells, three families of functionally important RasGEFs are expressed: RasGRF, RasGRP, and SOS-family GEFs.Early on it was recognized that Ras activation is critical for T cell development and that the RasGEFs play an important role herein. More recent work has revealed that nuances in Ras activation appear to significantly impact T cell development and selection. These nuances include distinct biochemical patterns of analog versus digital Ras activation, differences in cellular localization of Ras activation, and intricate interplays between the RasGEFs during distinct T cell developmental stages as revealed by various new mouse models. In many instances, the exact nature of these nuances in Ras activation or how these may result from fine-tuning of the RasGEFs is not understood.One large group of biomolecules critically involved in the control of Ras-GEFs´functions are lipid second messengers. Multiple, yet distinct lipid products are generated following T cell receptor (TCR stimulation and bind to different domains in the RasGRP and SOS RasGEFs to facilitate the activation of the membrane-anchored Ras GTPases. In this review we highlight how different lipid-based elements are generated by various enzymes downstream of the TCR and other receptors and how these dynamic and interrelated lipid products may fine-tune Ras activation by RasGEFs in developing T cells.

  15. MULTI-MESSENGER ASTRONOMY OF GRAVITATIONAL-WAVE SOURCES WITH FLEXIBLE WIDE-AREA RADIO TRANSIENT SURVEYS

    Energy Technology Data Exchange (ETDEWEB)

    Yancey, Cregg C.; Shawhan, Peter [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Bear, Brandon E.; Akukwe, Bernadine; Simonetti, John H.; Tsai, Jr-Wei [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Chen, Kevin [Department of Physics, The College of New Jersey, Ewing, NJ 08628 (United States); Dowell, Jayce; Obenberger, Kenneth; Taylor, Gregory B. [Department of Physics and Astronomy, University of New Mexico, Albuquerque NM, 87131 (United States); Gough, Jonathan D. [Department of Chemistry, Lehman College, Bronx, NY 10468 (United States); Kanner, Jonah [LIGO-California Institute of Technology, Pasadena, California CA 91125 (United States); Kavic, Michael [Department of Physics, Long Island University, Brooklyn, NY 11201 (United States)

    2015-10-20

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of GWs and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, the Low Frequency Array and the Murchison Widefield Array. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a ∼30 s time window and ∼200–500 deg{sup 2} sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a prompt radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of ∼2. For some models, we also map the parameter space that may be constrained by non-detections.

  16. The research and practice of spacecraft software engineering

    Science.gov (United States)

    Chen, Chengxin; Wang, Jinghua; Xu, Xiaoguang

    2017-06-01

    In order to ensure the safety and reliability of spacecraft software products, it is necessary to execute engineering management. Firstly, the paper introduces the problems of unsystematic planning, uncertain classified management and uncontinuous improved mechanism in domestic and foreign spacecraft software engineering management. Then, it proposes a solution for software engineering management based on system-integrated ideology in the perspective of spacecraft system. Finally, a application result of spacecraft is given as an example. The research can provides a reference for executing spacecraft software engineering management and improving software product quality.

  17. Contemporary state of spacecraft/environment interaction research

    CERN Document Server

    Novikov, L S

    1999-01-01

    Various space environment effects on spacecraft materials and equipment, and the reverse effects of spacecrafts and rockets on space environment are considered. The necessity of permanent updating and perfection of our knowledge on spacecraft/environment interaction processes is noted. Requirements imposed on models of space environment in theoretical and experimental researches of various aspects of the spacecraft/environment interaction problem are formulated. In this field, main problems which need to be solved today and in the nearest future are specified. The conclusion is made that the joint analysis of both aspects of spacecraft/environment interaction problem promotes the most effective solution of the problem.

  18. METRIC: A Dedicated Earth-Orbiting Spacecraft for Investigating Gravitational Physics and the Space Environment

    Science.gov (United States)

    Peron, R.; Lorenzini, E. C.

    2017-07-01

    A dedicated mission in low Earth orbit is proposed to test predictions of gravitational interaction theories and to directly measure the atmospheric density in a relevant altitude range, as well as to provide a metrological platform able to tie different space geodesy techniques. The concept foresees a small spacecraft to be placed in a dawn-dusk eccentric orbit between 450 and 1200 km of altitude. The spacecraft will be tracked from the ground with high precision, and a three-axis accelerometer package on-board will measure the non-gravitational accelerations acting on its surface. Estimates of parameters related to fundamental physics and geophysics should be obtained by a precise orbit determination, while the accelerometer data will be instrumental in constraining the atmospheric density. Along with the mission scientific objectives, a conceptual configuration is described together with an analysis of the dynamical environment experienced by the spacecraft and the acc! elerometer.

  19. Observations of interplanetary plasma waves, spacecraft noise, and sheath phenomena on Imp 7

    Science.gov (United States)

    Scarf, F. L.; Fredricks, R. W.; Green, I. M.; Crook, G. M.

    1974-01-01

    The Imp 7 plasma wave instrument measures electric and magnetic wave components of plasma oscillations over the frequency range from 10 Hz to 100 kHz. The instrumentation and relevant external characteristics of the spacecraft that appear to be responsible for some in-flight disturbance effects are briefly described. It is shown that as each one of the 16 solar panel flats rotates into shadow or sunlight, the array transients produce fluctuating magnetic fields that are detected on the magnetic loop mounted 3.4 m from the spacecraft. These transients occur 16 times per spin period, and the corresponding magnetic noise has a high frequency on the rapidly spinning Imp 7 spacecraft. The analysis suggests that some Imp magnetic threshold levels measured 3-4 m from the spacecraft are determined by the solar array current transient effects associated with the discrete 16-sided geometry of the spacecraft. The geometry also influences the response of the electric dipole antenna by modulating the sheath.

  20. Research-Based Monitoring, Prediction, and Analysis Tools of the Spacecraft Charging Environment for Spacecraft Users

    Science.gov (United States)

    Zheng, Yihua; Kuznetsova, Maria M.; Pulkkinen, Antti A.; Maddox, Marlo M.; Mays, Mona Leila

    2015-01-01

    The Space Weather Research Center (http://swrc. gsfc.nasa.gov) at NASA Goddard, part of the Community Coordinated Modeling Center (http://ccmc.gsfc.nasa.gov), is committed to providing research-based forecasts and notifications to address NASA's space weather needs, in addition to its critical role in space weather education. It provides a host of services including spacecraft anomaly resolution, historical impact analysis, real-time monitoring and forecasting, tailored space weather alerts and products, and weekly summaries and reports. In this paper, we focus on how (near) real-time data (both in space and on ground), in combination with modeling capabilities and an innovative dissemination system called the integrated Space Weather Analysis system (http://iswa.gsfc.nasa.gov), enable monitoring, analyzing, and predicting the spacecraft charging environment for spacecraft users. Relevant tools and resources are discussed.

  1. NEUTRINOS AS COSMIC MESSENGERS IN THE ERA OF ICECUBE, ANTARES AND KM3NET

    Directory of Open Access Journals (Sweden)

    Uli F. Katz

    2013-12-01

    Full Text Available Using neutrinos as cosmic messengers for observation of non-thermal processes in the Universe is a highly attractive and promising vision, which has been pursued in various neutrino telescope projects for more than two decades. Recent results from ground-based TeV gamma-ray observatories and refinements of model calculations of the expected neutrino fluxes indicate that Gigaton target volumes will be necessary to establish neutrino astronomy. A first neutrino telescope of that size, IceCube, is operational at the South Pole. Based on experience with the smaller first-generation ANTARES telescope in the Mediterranean Sea, the multi-Gigaton KM3NeT device is in preparation. These neutrino telescopes are presented, and some selected results and the expected KM3NeT performance are discussed.

  2. Effects of local structural transformation of lipid-like compounds on delivery of messenger RNA

    Science.gov (United States)

    Li, Bin; Luo, Xiao; Deng, Binbin; Giancola, Jolynn B.; McComb, David W.; Schmittgen, Thomas D.; Dong, Yizhou

    2016-02-01

    Lipid-like nanoparticles (LLNs) have shown great potential for RNA delivery. Lipid-like compounds are key components in LLNs. In this study, we investigated the effects of local structural transformation of lipid-like compounds on delivery of messenger RNA. Our results showed that position change of functional groups on lipid-like compounds can dramatically improve delivery efficiency. We then optimized formulation ratios of TNT-b10 LLNs, a lead material, increasing delivery efficiency over 2-fold. More importantly, pegylated TNT-b10 LLNs is stable for over four weeks and is over 10-fold more efficient than that of its counterpart TNT-a10 LLNs. Additionally, the optimal formulation O-TNT-b10 LLNs is capable of delivering mRNA encoding luciferase in vivo. These results provide useful insights into the design of next generation LLNs for mRNA delivery.

  3. Light is a Messenger - The Life and Science of William Lawrence Bragg

    Science.gov (United States)

    Hunter, Graeme K.

    2004-10-01

    Light is a Messenger , is the first biography of William Lawrence Bragg, who was only 25 when he won the 1915 Nobel Prize in Physics-the youngest person ever to win a Nobel Prize. It describes how bragg discovered how to use X-rays to determine the arrangement of atoms in crystals and his pivotal role in developing this technique to the point that the structures of the most complex molecules known to man-the proteins and nucelic acids-could be solved. Although Bragg's Nobel Prize was for Physics, his research profoundly affected chemistry and the new field of molecular biology, of which he became a founding figure. This book explains how these revolutionary scientific events occurred while Bragg struggled to emerge from the shadow of his father, Sir William Bragg, and amidst a career-long rivalry with the brilliant American chemist, Linus Pauling.

  4. Messenger RNA Fluctuations and Regulatory RNAs Shape the Dynamics of Negative Feedback Loop

    CERN Document Server

    Martínez, María Rodríguez; Tlusty, Tsvi; Pilpel, Yitzhak; Furman, Itay; 10.1103/PhysRevE.81.031924

    2010-01-01

    Single cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single cell level. Opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of non--coding regulatory RNAs in post--transcription regulation, we also consider the possibility that a regulatory RNA transcri...

  5. Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution.

    Science.gov (United States)

    Peplowski, Patrick N; Evans, Larry G; Hauck, Steven A; McCoy, Timothy J; Boynton, William V; Gillis-Davis, Jeffery J; Ebel, Denton S; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Nittler, Larry R; Solomon, Sean C; Rhodes, Edgar A; Sprague, Ann L; Starr, Richard D; Stockstill-Cahill, Karen R

    2011-09-30

    The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.

  6. RANCANG BANGUN APLIKASI AUTORESPONDER BERBASIS INSTANT MESSENGER GOOGLE HANGOUTS (Studi Kasus Perusahaan Valuta Asing

    Directory of Open Access Journals (Sweden)

    ita anariyanti ni putu

    2015-10-01

    Full Text Available Money Changer adalah salah satu bidang usaha dimana frekuensi pergantian data tinggi dan dibutuhkan penyajian informasi yang bersifat cepat dan real time. Aplikasi Autoresponder adalah salah satu pemanfaatan teknologi untuk mempermudah mendapatkan informasi valuta asing. Aplikasi dirancang untuk mampu memberikan respon/ jawaban ataupun hanya sekedar menampung dari sebuah masukan secara otomatis dari layanan instant messenger Google Hangouts. Dari aplikasi ini, cukup dengan meregistrasi diri sebagai teman dari akun Gmail valas server. Selanjutnya dari Google Hangouts dapat melakukan cek nilai valuta asing dengan masukan keyword tertentu. Keuntungan yang bisa diberikan oleh aplikasi Autoresponder dilihat dari sisi pengembang adalah biaya untuk proses produksi maupun perawatan yang minimum karena aplikasi Autoresponder menggunakan open source.

  7. Electromagnetic Dissociation and Spacecraft Electronics Damage

    Science.gov (United States)

    Norbury, John W.

    2016-01-01

    When protons or heavy ions from galactic cosmic rays (GCR) or solar particle events (SPE) interact with target nuclei in spacecraft, there can be two different types of interactions. The more familiar strong nuclear interaction often dominates and is responsible for nuclear fragmentation in either the GCR or SPE projectile nucleus or the spacecraft target nucleus. (Of course, the proton does not break up, except possibly to produce pions or other hadrons.) The less familiar, second type of interaction is due to the very strong electromagnetic fields that exist when two charged nuclei pass very close to each other. This process is called electromagnetic dissociation (EMD) and primarily results in the emission of neutrons, protons and light ions (isotopes of hydrogen and helium). The cross section for particle production is approximately defined as the number of particles produced in nucleus-nucleus collisions or other types of reactions. (There are various kinematic and other factors which multiply the particle number to arrive at the cross section.) Strong, nuclear interactions usually dominate the nuclear reactions of most interest that occur between GCR and target nuclei. However, for heavy nuclei (near Fe and beyond) at high energy the EMD cross section can be much larger than the strong nuclear interaction cross section. This paper poses a question: Are there projectile or target nuclei combinations in the interaction of GCR or SPE where the EMD reaction cross section plays a dominant role? If the answer is affirmative, then EMD mechanisms should be an integral part of codes that are used to predict damage to spacecraft electronics. The question can become more fine-tuned and one can ask about total reaction cross sections as compared to double differential cross sections. These issues will be addressed in the present paper.

  8. Spacecraft computer technology at Southwest Research Institute

    Science.gov (United States)

    Shirley, D. J.

    1993-01-01

    Southwest Research Institute (SwRI) has developed and delivered spacecraft computers for a number of different near-Earth-orbit spacecraft including shuttle experiments and SDIO free-flyer experiments. We describe the evolution of the basic SwRI spacecraft computer design from those weighing in at 20 to 25 lb and using 20 to 30 W to newer models weighing less than 5 lb and using only about 5 W, yet delivering twice the processing throughput. Because of their reduced size, weight, and power, these newer designs are especially applicable to planetary instrument requirements. The basis of our design evolution has been the availability of more powerful processor chip sets and the development of higher density packaging technology, coupled with more aggressive design strategies in incorporating high-density FPGA technology and use of high-density memory chips. In addition to reductions in size, weight, and power, the newer designs also address the necessity of survival in the harsh radiation environment of space. Spurred by participation in such programs as MSTI, LACE, RME, Delta 181, Delta Star, and RADARSAT, our designs have evolved in response to program demands to be small, low-powered units, radiation tolerant enough to be suitable for both Earth-orbit microsats and for planetary instruments. Present designs already include MIL-STD-1750 and Multi-Chip Module (MCM) technology with near-term plans to include RISC processors and higher-density MCM's. Long term plans include development of whole-core processors on one or two MCM's.

  9. Combined space environment on spacecraft engineering materials

    Science.gov (United States)

    Workman, Gary L.; Smith, Guy A.; Kosten, Susan

    1993-01-01

    Spacecraft structures and surface materials exposed to the space environment for extended periods, up to thirty years, have increased potential for damage from long term exposure to the combined space environment including solar ultraviolet radiation, electrons, and protons and orbiting space debris. The space environment in which the Space Station Freedom and other space platforms will orbit is truly a hostile environment. For example, the currently estimated integral fluence for electrons above 1 Mev at 2000 nautical miles is above 2 x 10(exp 10) electrons/cm(sup 2)/day and the proton integral fluence is above 1 x 10(exp 9) protons/cm(sup 2)/day. At the 200 - 400 nautical miles, which is more representative of the altitude which will provide the environment for the Space Station, each of these fluences will be proportionately less; however, the data indicates that the radiation environment will obviously have an effect on structural materials exposed to the environment for long durations. The effects of ultraviolet radiation, particularly in the vacuum ultraviolet (less than 200 nm wavelength) is more difficult to characterize at this time. Very little data is available in the literature which can be used for determining the life cycle of a material placed in space for extended durations of time. In order to obtain critical data for planning and designing of spacecraft systems, use of a small vacuum system at the Environmental Effects Facility at MSFC, which can be used for these purposes was used. A special effort was made to build up this capability during the course of this research effort and perform a variety of experiments on materials proposed for the Space Station. A description of the apparatus and the procedure devised to process potential spacecraft materials is included.

  10. Spacecraft Maximum Allowable Concentrations for Airborne Contaminants

    Science.gov (United States)

    James, John T.

    2008-01-01

    The enclosed table lists official spacecraft maximum allowable concentrations (SMACs), which are guideline values set by the NASA/JSC Toxicology Group in cooperation with the National Research Council Committee on Toxicology (NRCCOT). These values should not be used for situations other than human space flight without careful consideration of the criteria used to set each value. The SMACs take into account a number of unique factors such as the effect of space-flight stress on human physiology, the uniform good health of the astronauts, and the absence of pregnant or very young individuals. Documentation of the values is given in a 5 volume series of books entitled "Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants" published by the National Academy Press, Washington, D.C. These books can be viewed electronically at http://books.nap.edu/openbook.php?record_id=9786&page=3. Short-term (1 and 24 hour) SMACs are set to manage accidental releases aboard a spacecraft and permit risk of minor, reversible effects such as mild mucosal irritation. In contrast, the long-term SMACs are set to fully protect healthy crewmembers from adverse effects resulting from continuous exposure to specific air pollutants for up to 1000 days. Crewmembers with allergies or unusual sensitivity to trace pollutants may not be afforded complete protection, even when long-term SMACs are not exceeded. Crewmember exposures involve a mixture of contaminants, each at a specific concentration (C(sub n)). These contaminants could interact to elicit symptoms of toxicity even though individual contaminants do not exceed their respective SMACs. The air quality is considered acceptable when the toxicity index (T(sub grp)) for each toxicological group of compounds is less than 1, where T(sub grp), is calculated as follows: T(sub grp) = C(sub 1)/SMAC(sub 1) + C(sub 2/SMAC(sub 2) + ...+C(sub n)/SMAC(sub n).

  11. Spacecraft fabrication and test MODIL. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T.T.

    1994-05-01

    This report covers the period from October 1992 through the close of the project. FY 92 closed out with the successful briefing to industry and with many potential and important initiatives in the spacecraft arena. Due to the funding uncertainties, we were directed to proceed as if our funding would be approximately the same as FY 92 ($2M), but not to make any major new commitments. However, the MODIL`s FY 93 funding was reduced to $810K and we were directed to concentrate on the cryocooler area. The cryocooler effort completed its demonstration project. The final meetings with the cryocooler fabricators were very encouraging as we witnessed the enthusiastic reception of technology to help them reduce fabrication uncertainties. Support of the USAF Phillips Laboratory cryocooler program was continued including kick-off meetings for the Prototype Spacecraft Cryocooler (PSC). Under Phillips Laboratory support, Gill Cruz visited British Aerospace and Lucas Aerospace in the United Kingdom to assess their manufacturing capabilities. In the Automated Spacecraft & Assembly Project (ASAP), contracts were pursued for the analysis by four Brilliant Eyes prime contractors to provide a proprietary snap shot of their current status of Integrated Product Development. In the materials and structure thrust the final analysis was completed of the samples made under the contract (``Partial Automation of Matched Metal Net Shape Molding of Continuous Fiber Composites``) to SPARTA. The Precision Technologies thrust funded the Jet Propulsion Laboratory to prepare a plan to develop a Computer Aided Alignment capability to significantly reduce the time for alignment and even possibly provide real time and remote alignment capability of systems in flight.

  12. Applying computer techniques in maxillofacial reconstruction using a fibula flap: a messenger and an evaluation method.

    Science.gov (United States)

    Liu, Xiao-jing; Gui, Lai; Mao, Chi; Peng, Xin; Yu, Guang-yan

    2009-03-01

    While the application of computer-assisted maxillofacial surgery becomes increasingly popular, the translation from virtual models and surgical plans to actual bedside maneuvers and the evaluation of the repeatability of virtual planning remain to be major challenges. The objective of this study was to experiment the technique of using a resin template as a messenger in maxillofacial reconstruction involving a fibula flap. Another aim was to find a quantitative and objective method to evaluate the repeatability of preoperative planning. Seven patients who underwent maxillary or mandibular reconstruction were included in this study. The mean age was 25 years, and the mean follow-up period was 18.7 months. Virtual planning was carried out before surgery. A resin template was made according to the virtual design of bone graft through rapid prototyping technique and served as a guide when surgeons shaped the fibula flap during surgery. The repeatability of the virtual plan was evaluated based on the matching percentage between the actual postoperative model and the computer-generated outcome. All patients demonstrated satisfactory clinical outcomes. The mean repeatability was 87.5% within 1 mm and 96.5% within 2 mm in isolated bone graft. It was 71.4% within 1 mm and 89.9% within 2 mm in reconstructed mandible or maxilla. These results demonstrated that a resin template based on virtual plan and rapid prototyping technique is a reliable messenger to translate from computer modeling to bedside surgical procedures. The repeatability of a virtual plan can be easily and quantitatively evaluated through our three-dimensional differential analysis method.

  13. Gastrin response to candidate messengers in intact conscious rats monitored by antrum microdialysis.

    Science.gov (United States)

    Ericsson, Peter; Håkanson, Rolf; Norlén, Per

    2010-08-09

    We monitored gastrin release in response to locally applied candidate messengers in intact conscious rats. Earlier studies have been performed on anaesthetized animals, isolated pieces of antrum, or purified preparations of gastrin cells. In this study we created an experimental situation to resemble physiological conditions, using reverse microdialysis to administer regulatory peptides and amines that might affect gastrin secretion. Microdialysis probes were implanted in the submucosa of the antrum of the rat stomach. Three days later, putative messenger compounds were administered via the probe. Their effects on basal (24 h fast) and omeprazole-stimulated (400 micromol/kg/day, 4 days peroral administration) gastrin release were monitored by continuous measurement (3 h) of gastrin in the perfusate (radioimmunoassay). Fasted rats (low microdialysate gastrin, 2.1+/-0.1 pmol l(-1)) were used to study stimulation of gastrin release. Omeprazole-treated rats (high microdialysate gastrin, 95.8+/-6.7 pmol l(-1)) were used to study suppression of gastrin release. The following agents raised the concentration of microdialysate gastrin (peak response): gastrin-releasing peptide (GRP) (11-fold increase at a near-maximal dose), carbachol (5-fold increase), serotonin (2-fold increase) and isoprenaline (20-fold increase). Adrenaline and noradrenaline induced transient but powerful elevation (40- and 20-fold increase). Somatostatin, galanin and bradykinin (at near-maximal doses) suppressed omeprazole-stimulated gastrin release (50% decrease). Calcitonin gene-related peptide, ghrelin, gastric inhibitory peptide, motilin, neurotensin, neuromedin U-25, peptide YY and vasoactive intestinal peptide were without effect on gastrin release, as were aspartate, gamma-aminobutyric acid, glutamate, glycine, dopamine and histamine. The results support the view that G cells operate under neurocrine/paracrine control. They were stimulated by agents present in enteric neurons (GRP, galanin

  14. Serotonergic transmission at Merkel discs: modulation by exogenously applied chemical messengers and involvement of Ih currents.

    Science.gov (United States)

    Chang, Weipang; Kanda, Hirosato; Ikeda, Ryo; Ling, Jennifer; Gu, Jianguo G

    2017-05-01

    The Merkel disc is a main type of tactile end organ consisting of Merkel cells and Aβ-afferent endings that responds to tactile stimulation with slowly adapting type 1 (SA1) afferent impulses. Our recent study has shown that Merkel discs in whisker hair follicles are serotonergic synapses using endogenous serotonin to transmit tactile signals from Merkel cells to Aβ-afferent endings. In this study, we hypothesize that tactile sensitivity of Merkel discs can be modulated by chemical messengers. We tested this hypothesis by determining whether and how SA1 responses of mouse whisker hair follicles may be affected by exogenously applied chemical messengers. We found that SA1 responses were potentiated by serotonin at low concentration (10 μM) but almost completely occluded by serotonin at high concentration (2 mM). In contrast, SA1 responses were not significantly affected by ATP and its metabolically stable analog α,β-methylene-ATP, glutamate, γ-aminobutyric acid (GABA), and histamine. SA1 responses were also not affected by antagonists for P2X receptors, ionotropic glutamate receptors, and ionotropic GABA and glycine receptors. Whole-cell patch-clamp recordings reconfirm the presence of both ionotropic and metabotropic 5-HT receptors on afferent neurons and their terminals innervating whisker hair follicles. All whisker afferent neurons expressed hyperpolarization-activated inward currents (Ih ), which are potentiated by serotonin through the activation of metabotropic 5-HT receptors. Taken together, the findings substantiate the serotonergic mechanism of tactile transmission at Merkel discs and identify the involvement of Ih currents in postsynaptic excitatory actions of serotonin. In addition, the findings do not favor any significant involvement of ATP, glutamate, histamine, GABA, or glycine in tactile transmission at the Merkel discs of whisker hair follicles. © 2017 International Society for Neurochemistry.

  15. Linking The Universe To The Community: Students As Starry Messengers For IYA2009-Puerto Rico.

    Science.gov (United States)

    Pantoja, Carmen; Lebrón, M.

    2008-05-01

    This poster presents a project at Puerto Rico to establish a working team of undergraduate students (Starry Messengers) to promote and experience the wonders of space science and education with all the senses. The students are expected to assist during the activities of the International Year of Astronomy 2009 (IYA2009). During 2008 the students will receive the appropriate instruction on observational astronomy through two workshops. These workshops follow the active learning model and therefore prepare students for outreach activities in astronomy. An innovative model of inclusion will be developed, adapting all the activities and material to include blind or visually impaired. We will encourage the participation of at least one visually impaired student or teacher on the Starry Messengers team. The greatest challenge in this project will be to develop adequate accessible activities in astronomy. The workshops will be held at the Arecibo Observatory and "El Parque de las Ciencias" Planetarium. These two centers have the facilities to develop the workshops and have the adequate settings for the participants to gain experience with astronomy research and outreach. This project targets underrepresented groups in science and engineering: hispanic students and students with visual impairments. The inquiry-based learning activities and material designed as part of the program will also be made available to the public to further promote excellence in astronomy. The workshops will serve as templates for future K-12 teacher workshops. This work has been funded by the NASA IDEAS-ER program. We would like to acknowledge the support from the Arecibo Observatory. The Arecibo Observatory is part of the National Astronomy and Ionospheric Center, which is operated by Cornell University under a Cooperative agreement with the National Science Foundation.

  16. Second messenger signaling mechanisms of the brown adipocyte thermogenic program: an integrative perspective.

    Science.gov (United States)

    Shi, Fubiao; Collins, Sheila

    2017-09-26

    β-adrenergic receptors (βARs) are well established for conveying the signal from catecholamines to adipocytes. Acting through the second messenger cyclic adenosine monophosphate (cAMP) they stimulate lipolysis and also increase the activity of brown adipocytes and the 'browning' of adipocytes within white fat depots (so-called 'brite' or 'beige' adipocytes). Brown adipose tissue mitochondria are enriched with uncoupling protein 1 (UCP1), which is a regulated proton channel that allows the dissipation of chemical energy in the form of heat. The discovery of functional brown adipocytes in humans and inducible brown-like ('beige' or 'brite') adipocytes in rodents have suggested that recruitment and activation of these thermogenic adipocytes could be a promising strategy to increase energy expenditure for obesity therapy. More recently, the cardiac natriuretic peptides and their second messenger cyclic guanosine monophosphate (cGMP) have gained attention as a parallel signaling pathway in adipocytes, with some unique features. In this review, we begin with some important historical work that touches upon the regulation of brown adipocyte development and physiology. We then provide a synopsis of some recent advances in the signaling cascades from β-adrenergic agonists and natriuretic peptides to drive thermogenic gene expression in the adipocytes and how these two pathways converge at a number of unexpected points. Finally, moving from the physiologic hormonal signaling, we discuss yet another level of control downstream of these signals: the growing appreciation of the emerging roles of non-coding RNAs as important regulators of brown adipocyte formation and function. In this review, we discuss new developments in our understanding of the signaling mechanisms and factors including new secreted proteins and novel non-coding RNAs that control the function as well as the plasticity of the brown/beige adipose tissue as it responds to the energy needs and environmental

  17. Messenger RNA during early embryogenesis in Artemia salina: altered translatability and sequence complexity.

    Science.gov (United States)

    James, T C; Tata, J R

    1980-02-01

    RNA from developing embryos of Artemia salina (5, 10, and 20 h after re-initiation of development) was translated 3-10 times more efficiently in a rabbit reticulocyte lysate cell-free protein synthesizing system than RNA from dormant gastrulae. The latter did not appear to contain any significant amount of translation inhibitor activity. Ninety percent of the translatable activity in dormant gastrulae was recovered as poly(A)--RNA, whereas 80% of that in post-gastrular developing embryos was present as poly(A)+-RNA. The size of most polypeptides coded for by dormant gastrular RNA was less than 130,000 daltons whereas the size of those coded for by developing embryonic RNA was up to 200,000 daltons, which correlated with a corresponding shift to poly A-containing RNA of higher molecular weight. Two major polypeptides of about 37,000 daltons coded for by dormant gastrular RNA disappeared at 20 h after resumption of development. Hybridization of complementary DNA (cDNA) to a 1000-fold excess of the homologous poly(A)+-RNA revealed the presence of three complexity classes of mRNA. Forty-five percent, 30%, and 25% of RNA in dormant gastrulae were present as high, middle, and low abundance classes comprising about 10, 80, and 9700 species, respectively whereas in the nauplii there were 10, 150, and 7900 species of high, middle, and low abundancy sequences, respectively. Heterologous hybridizations using cDNA complementary to highly abundant messenger population of nauplii (isolated by chromatography on hydroxyapatite) to poly(A)+-RNA from dormant cysts showed considerably divergence in this class of messengers from the two developmental stages. Re-initiation of development of dormant Artemia gastrulae is thus characterized by a "re-programming" seen as a simultaneous and rapid increase in the polyadenylation and translatability of poly(A)+-RNA accompanied by a qualitative change in its sequence complexity.

  18. Fault Detection and Isolation for Spacecraft

    DEFF Research Database (Denmark)

    Jensen, Hans-Christian Becker; Wisniewski, Rafal

    2002-01-01

    This article realizes nonlinear Fault Detection and Isolation for actuators, given there is no measurement of the states in the actuators. The Fault Detection and Isolation of the actuators is instead based on angular velocity measurement of the spacecraft and knowledge about the dynamics...... of the satellite. The algorithms presented in this paper are based on a geometric approach to achieve nonlinear Fault Detection and Isolation. The proposed algorithms are tested in a simulation study and the pros and cons of the algorithms are discussed....

  19. Electrical Power Subsystem for the Euclid Spacecraft

    OpenAIRE

    Ciancetta Ezio; Cimino Marco; Cuzzocrea Giuseppe; Gervasio Giuseppe; Maiorano Elena; Martinez Ignacio; Sanchez Luc

    2017-01-01

    European Space Agency in the frame of Cosmic Vision 2015-2025 program [ 1 ]. It is a cosmology mission whose prime objective is to study the geometry and the nature of the dark matter and the dark energy with unprecedented accuracy. The spacecraft will be launched in 2020 by a Soyuz launcher, to perform a six-year survey of the extragalactic sky from a large-amplitude orbit around Lagrange point L2 of the Sun-Earth system. This paper outlines the Euclid Electrical Power Subsystem (EPS) ...

  20. Conducted Transients on Spacecraft Primary Power Lines

    Science.gov (United States)

    Mc Closkey, John; Dimov, Jen

    2017-01-01

    One of the sources of potential interference on spacecraft primary power lines is that of conducted transients resulting from equipment being switched on and off of the bus. Susceptibility to such transients is addressed by some version of the CS06 requirement of MIL-STD-461462. This presentation provides a summary of the history of the CS06 requirement and test method, a basis for understanding of the sources of these transients, analysis techniques for determining their worst-case characteristics, and guidelines for minimizing their magnitudes and applying the requirement appropriately.

  1. Large Scale Experiments on Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Urban, David L.; Ruff, Gary A.; Minster, Olivier

    2012-01-01

    Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due......-based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal-gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame...

  2. Maternal provision of non-sex-specific transformer messenger RNA in sex determination of the wasp Asobara tabida

    NARCIS (Netherlands)

    Geuverink, Elzemiek; Verhulst, E.C.; Leussen, van M.; Zande, L.; Beukeboom, Leo W.

    2017-01-01

    In many insect species maternal provision of sex-specifically spliced messenger RNA (mRNA) of sex determination genes is an essential component of the sex determination mechanism. In haplodiploid Hymenoptera, maternal provision in combination with genomic imprinting has been shown for the parasitoid

  3. Differential intragraft cytokine messenger RNA profiles during rejection and repair of clinical heart transplants. A longitudinal study

    NARCIS (Netherlands)

    de Groot-Kruseman, Hester A; Mol, Wendy M; Niesters, Hubert G M; Maat, Alex P W; van Gelder, Teun; Balk, Aggie H M M; Weimar, Willem; Baan, Carla C

    After clinical heart transplantation, ischemia, acute rejection, and repair mechanisms can trigger the up-regulation of cytokines. To investigate the cytokine profile early after transplantation, we monitored messenger RNA (mRNA) expression levels of tumor necrosis factor-alpha (TNF-alpha), monocyte

  4. Gene Expression in Archaea: Studies of Transcriptional Promoters, Messenger RNA Processing, and Five Prime Untranslated Regions in "Methanocaldococcus Jannashchii"

    Science.gov (United States)

    Zhang, Jian

    2009-01-01

    Gene expression in Archaea is less understood than those in Bacteria and Eucarya. In general, three steps are involved in gene expression--transcription, RNA processing, and translation. To expand our knowledge of these processes in Archaea, I have studied transcriptional promoters, messenger RNA processing, and 5'-untranslated regions in…

  5. Just How Important Is the Messenger versus the Message? The Case of Framing Physician-Assisted Suicide

    Science.gov (United States)

    Haider-Markel, Donald P.; Joslyn, Mark R.

    2004-01-01

    As a political issue, death and dying topics only sometimes reach the political agenda. However, some issues, such as physician-assisted suicide (PAS) have been highly salient. This article explores attitudes toward PAS by examining the malleability of opinion when respondents are exposed to issue frames and when specific messengers present those…

  6. Maternal provision of non-sex-specific transformer messenger RNA in sex determination of the wasp Asobara tabida

    NARCIS (Netherlands)

    Geuverink, Elzemiek; Verhulst, E.C.; Leussen, van M.; Zande, L.; Beukeboom, Leo W.

    2018-01-01

    In many insect species maternal provision of sex-specifically spliced messenger RNA (mRNA) of sex determination genes is an essential component of the sex determination mechanism. In haplodiploid Hymenoptera, maternal provision in combination with genomic imprinting has been shown for the parasitoid

  7. The Effectiveness of Using WhatsApp Messenger as One of Mobile Learning Techniques to Develop Students' Writing Skills

    Science.gov (United States)

    Fattah, Said Fathy El Said Abdul

    2015-01-01

    The present study was an attempt to determine the effectiveness of using a WhatsApp Messenger as one of mobile learning techniques to develop students' writing skills. Participants were 30 second year college students, English department from a private university in Saudi Arabia. The experimental group (N = 15) used WhatsApp technology to develop…

  8. Flex Dynamics Avoidance Control of the NEA Scout Solar Sail Spacecraft's Reaction Control System

    Science.gov (United States)

    Heaton Andrew; Stiltner, Brandon; Diedrich, Benjamin; Becker, Christopher; Orphee, Juan

    2017-01-01

    The Attitude Control System (ACS) is developed for a Near Earth Asteroid (NEA) Scout mission using a solar sail. The NEA-Scout spacecraft is a 6U cubesat with an 86 square-meter solar sail. NEA Scout will launch on Space Launch System (SLS) Exploration Mission 1 (EM-1), currently scheduled to launch in 2018. The spacecraft will rendezvous with a target asteroid after a two year journey, and will conduct science imagery. The solar sail spacecraft ACS consists of three major actuating subsystems: a Reaction Wheel (RW) control system, a Reaction Control System (RCS), and an Adjustable Mass Translator (AMT) system. The three subsystems allow for a wide range of spacecraft attitude control capabilities, needed for the different phases of the NEA-Scout mission. Because the sail is a flexible structure, care must be taken in designing a control system to avoid exciting the structural modes of the sail. This is especially true for the RCS, which uses pulse actuated, cold-gas jets to control the spacecraft's attitude. While the reaction wheels can be commanded smoothly, the RCS jets are simple on-off actuators. Long duration firing of the RCS jets - firings greater than one second - can be thought of as step inputs to the spacecraft's torque. On the other hand, short duration firings - pulses on the order of 0.1 seconds - can be thought of as impulses in the spacecraft's torque. These types of inputs will excite the structural modes of the spacecraft, causing the sail to oscillate. Sail oscillations are undesirable for many reasons. Mainly, these oscillations will feed into the spacecraft attitude sensors and pointing accuracy, and long term oscillations may be undesirable over the lifetime of the solar sail. In order to limit the sail oscillations, an RCS control scheme is being developed to minimize sail excitations. Specifically, an input shaping scheme similar to the method described in Reference 1 will be employed. A detailed description of the RCS control scheme will

  9. Adaptive System Modeling for Spacecraft Simulation

    Science.gov (United States)

    Thomas, Justin

    2011-01-01

    This invention introduces a methodology and associated software tools for automatically learning spacecraft system models without any assumptions regarding system behavior. Data stream mining techniques were used to learn models for critical portions of the International Space Station (ISS) Electrical Power System (EPS). Evaluation on historical ISS telemetry data shows that adaptive system modeling reduces simulation error anywhere from 50 to 90 percent over existing approaches. The purpose of the methodology is to outline how someone can create accurate system models from sensor (telemetry) data. The purpose of the software is to support the methodology. The software provides analysis tools to design the adaptive models. The software also provides the algorithms to initially build system models and continuously update them from the latest streaming sensor data. The main strengths are as follows: Creates accurate spacecraft system models without in-depth system knowledge or any assumptions about system behavior. Automatically updates/calibrates system models using the latest streaming sensor data. Creates device specific models that capture the exact behavior of devices of the same type. Adapts to evolving systems. Can reduce computational complexity (faster simulations).

  10. Relativistic effects of spacecraft with circumnavigating observer

    Science.gov (United States)

    Shanklin, Nathaniel; West, Joseph

    A variation of the recently introduced Trolley Paradox, itself is a variation of the Ehrenfest Paradox is presented. In the Trolley Paradox, a ``stationary'' set of observers tracking a wheel rolling with a constant velocity find that the wheel travels further than its rest length circumference during one revolution of the wheel, despite the fact that the Lorentz contracted circumference is less than its rest value. In the variation presented, a rectangular spacecraft with onboard observers moves with constant velocity and is circumnavigated by several small ``sloops'' forming teams of inertial observers. This whole precession moves relative to a set of ``stationary'' Earth observers. Two cases are presented, one in which the sloops are evenly spaced according to the spacecraft observers, and one in which the sloops are evenly spaced according to the Earth observes. These two cases, combined with the rectangular geometry and an emphasis on what is seen by, and what is measured by, each set of observers is very helpful in sorting out the apparent contradictions. To aid in the visualizations stationary representations in excel along with animation in Visual Python and Unity are presented. The analysis presented is suitable for undergraduate physics majors.

  11. Space Weathering Experiments on Spacecraft Materials

    Science.gov (United States)

    Cooper, R.; Cowardin, H.; Engelhar, D.; Plis, Elena; Hoffman, R.

    2017-01-01

    A project to investigate space environment effects on specific materials with interest to remote sensing was initiated in 2016. The goal of the project is to better characterize changes in the optical properties of polymers and Mylar, specifically those found in multi-layered spacecraft insulation, due to electron bombardment. Previous analysis shows that chemical bonds break and potentially reform when exposed to high energy electrons. Among other properties these chemical changes altered the optical reflectance as documented in laboratory analysis. This paper presents results of the initial experiment results focused on the exposure of materials to various fluences of high energy electrons, used to simulate a portion of the geosynchronous space environment. The paper illustrates how the spectral reflectance changes as a function of time on orbit with respect to GEO environmental factors and investigates the survivability of the material after multiple electron doses. These results provide a baseline for analysis of aging effects on satellite systems used for remote sensing. They also provide preliminary analysis on what materials are most likely to encompass the high area-to-mass population of space debris in the geosynchronous environment. Lastly, the paper provides the results of the initial experimentation as a proof of concept for space aging on polymers and Mylar for conducting more experiments with a larger subset of spacecraft materials.

  12. Electrodeless plasma thrusters for spacecraft: A review

    Science.gov (United States)

    Bathgate, S. N.; Bilek, M. M. M.; McKenzie, D. R.

    2017-08-01

    The physics of electrodeless electric thrusters that use directed plasma to propel spacecraft without employing electrodes subject to plasma erosion is reviewed. Electrodeless plasma thrusters are potentially more durable than presently deployed thrusters that use electrodes such as gridded ion, Hall thrusters, arcjets and resistojets. Like other plasma thrusters, electrodeless thrusters have the advantage of reduced fuel mass compared to chemical thrusters that produce the same thrust. The status of electrodeless plasma thrusters that could be used in communications satellites and in spacecraft for interplanetary missions is examined. Electrodeless thrusters under development or planned for deployment include devices that use a rotating magnetic field; devices that use a rotating electric field; pulsed inductive devices that exploit the Lorentz force on an induced current loop in a plasma; devices that use radiofrequency fields to heat plasmas and have magnetic nozzles to accelerate the hot plasma and other devices that exploit the Lorentz force. Using metrics of specific impulse and thrust efficiency, we find that the most promising designs are those that use Lorentz forces directly to expel plasma and those that use magnetic nozzles to accelerate plasma.

  13. Processing Images of Craters for Spacecraft Navigation

    Science.gov (United States)

    Cheng, Yang; Johnson, Andrew E.; Matthies, Larry H.

    2009-01-01

    A crater-detection algorithm has been conceived to enable automation of what, heretofore, have been manual processes for utilizing images of craters on a celestial body as landmarks for navigating a spacecraft flying near or landing on that body. The images are acquired by an electronic camera aboard the spacecraft, then digitized, then processed by the algorithm, which consists mainly of the following steps: 1. Edges in an image detected and placed in a database. 2. Crater rim edges are selected from the edge database. 3. Edges that belong to the same crater are grouped together. 4. An ellipse is fitted to each group of crater edges. 5. Ellipses are refined directly in the image domain to reduce errors introduced in the detection of edges and fitting of ellipses. 6. The quality of each detected crater is evaluated. It is planned to utilize this algorithm as the basis of a computer program for automated, real-time, onboard processing of crater-image data. Experimental studies have led to the conclusion that this algorithm is capable of a detection rate >93 percent, a false-alarm rate <5 percent, a geometric error <0.5 pixel, and a position error <0.3 pixel.

  14. Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis.

    Directory of Open Access Journals (Sweden)

    Leonid E Fridlyand

    Full Text Available Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR, cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1, glucose-dependent insulinotropic polypeptide (GIP and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA (that act through the FFA receptors on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of

  15. Orbital multispectral mapping of Mercury with the MESSENGER Mercury Dual Imaging System: Evidence for the origins of plains units and low-reflectance material

    Science.gov (United States)

    Murchie, Scott L.; Klima, Rachel L.; Denevi, Brett W.; Ernst, Carolyn M.; Keller, Mary R.; Domingue, Deborah L.; Blewett, David T.; Chabot, Nancy L.; Hash, Christopher D.; Malaret, Erick; Izenberg, Noam R.; Vilas, Faith; Nittler, Larry R.; Gillis-Davis, Jeffrey J.; Head, James W.; Solomon, Sean C.

    2015-07-01

    A principal data product from MESSENGER's primary orbital mission at Mercury is a global multispectral map in eight visible to near-infrared colors, at an average pixel scale of 1 km, acquired by the Mercury Dual Imaging System. The constituent images have been calibrated, photometrically corrected to a standard geometry, and map projected. Global analysis reveals no spectral units not seen during MESSENGER's Mercury flybys and supports previous conclusions that most spectral variation is related to changes in spectral slope and reflectance between spectral end-member high-reflectance red plains (HRP) and low-reflectance material (LRM). Comparison of color properties of plains units mapped on the basis of morphology shows that the two largest unambiguously volcanic smooth plains deposits (the interior plains of Caloris and the northern plains) are close to HRP end members and have average color properties distinct from those of most other smooth plains and intercrater plains. In contrast, smaller deposits of smooth plains are nearly indistinguishable from intercrater plains on the basis of their range of color properties, consistent with the interpretation that intercrater plains are older equivalents of smooth plains. LRM having nearly the same reflectance is exposed in crater and basin ejecta of all ages, suggesting impact excavation from depth of material that is intrinsically dark or darkens very rapidly, rather than gradual darkening of exposed material purely by space weathering. A global search reveals no definitive absorptions attributable to Fe2+-containing silicates or to sulfides over regions 20 km or more in horizontal extent, consistent with results from MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer. The only absorption-like feature identified is broad upward curvature of the spectrum centered near 600 nm wavelength. The feature is strongest in freshly exposed LRM and weak or absent in older exposures of LRM. We modeled spectra

  16. Geologic map and structural analysis of the Victoria quadrangle (H2) of Mercury based on NASA MESSENGER images

    Science.gov (United States)

    Galluzzi, V.; Di Achille, G.; Ferranti, L.; Rothery, D. A.; Palumbo, P.

    The first stratigraphic and geologic study of Mercury was released by Trask & Guest (1975) followed by Spudis & Guest (1988, and references therein), whose work was based on the images taken by Mariner 10 covering 42% of the total surface of Mercury. The planet has been officially divided into fifteen quadrangles: 2 polar, 5 equatorial and 8 at midlatitudes. Quadrangle H2 (= Hermes sheet n.2), named ``Victoria'' (20oN - 65oN Lon.; 270oE - 0o Lat.), was partially mapped by McGill & King (1983), though a wide area (˜64%) remained unmapped due to the lack of imagery. Following the terrain units recognized and described by the above authors, we have produced a geologic map of the entire quadrangle using MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) images. The images taken by the Mercury Dual Imaging System (MDIS) Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) allowed us to map geologic and tectonic features in much greater detail than the previously published map (mapping scale range between 1:300k and 1:600k). We classified craters larger than 20 km using three relative age classes, which are a simplification of the past five degradation classes defined by McCauley et al. (1981). Victoria quadrangle is characterized by a localized N-S thrust array constituted by Victoria Rupes, Endeavour Rupes and Antoniadi Dorsum to the East and by a more diffuse system of NE-SW oriented fault arrays to the West: the two systems seem to be separated by a tectonic bulge. The Victoria-Endeavour-Antoniadi system has been interpreted as a fold-and-thrust belt by Byrne et al. (2014) and a previous study made on craters cross-cut by its thrusts reveals fault dips of 15-20o and a near dip slip motion (Galluzzi et al., 2015). This geologic map has the aim to build a regional model of its structural framework. Deciphering the geological setting of this quadrangle will bring important insights for understanding the tectonic evolution of the whole planet

  17. Electromagnetic Forces on a Relativistic Spacecraft in the Interstellar Medium

    Science.gov (United States)

    Hoang, Thiem; Loeb, Abraham

    2017-10-01

    A relativistic spacecraft of the type envisioned by the Breakthrough Starshot initiative will inevitably become charged through collisions with interstellar particles and UV photons. Interstellar magnetic fields would therefore deflect the trajectory of the spacecraft. We calculate the expected deflection for typical interstellar conditions. We also find that the charge distribution of the spacecraft is asymmetric, producing an electric dipole moment. The interaction between the moving electric dipole and the interstellar magnetic field is found to produce a large torque, which can result in fast oscillation of the spacecraft around the axis perpendicular to the direction of motion, with a period of ˜0.5 hr. We then study the spacecraft rotation arising from impulsive torques by dust bombardment. Finally, we discuss the effect of the spacecraft rotation and suggest several methods to mitigate it.

  18. Spacecraft Dynamics Should be Considered in Kalman Filter Attitude Estimation

    Science.gov (United States)

    Yang, Yaguang; Zhou, Zhiqiang

    2016-01-01

    Kalman filter based spacecraft attitude estimation has been used in some high-profile missions and has been widely discussed in literature. While some models in spacecraft attitude estimation include spacecraft dynamics, most do not. To our best knowledge, there is no comparison on which model is a better choice. In this paper, we discuss the reasons why spacecraft dynamics should be considered in the Kalman filter based spacecraft attitude estimation problem. We also propose a reduced quaternion spacecraft dynamics model which admits additive noise. Geometry of the reduced quaternion model and the additive noise are discussed. This treatment is more elegant in mathematics and easier in computation. We use some simulation example to verify our claims.

  19. Pose and Shape Reconstruction of a Noncooperative Spacecraft Using Camera and Range Measurements

    National Research Council Canada - National Science Library

    Renato Volpe; Marco Sabatini; Giovanni B. Palmerini

    2017-01-01

    .... Various mission architectures have been either tested in space or studied on Earth. The present study deals with on-orbit relative pose and shape estimation with the use of a monocular camera and a distance sensor...

  20. Pose and Shape Reconstruction of a Noncooperative Spacecraft Using Camera and Range Measurements

    Directory of Open Access Journals (Sweden)

    Renato Volpe

    2017-01-01

    Full Text Available Recent interest in on-orbit proximity operations has pushed towards the development of autonomous GNC strategies. In this sense, optical navigation enables a wide variety of possibilities as it can provide information not only about the kinematic state but also about the shape of the observed object. Various mission architectures have been either tested in space or studied on Earth. The present study deals with on-orbit relative pose and shape estimation with the use of a monocular camera and a distance sensor. The goal is to develop a filter which estimates an observed satellite’s relative position, velocity, attitude, and angular velocity, along with its shape, with the measurements obtained by a camera and a distance sensor mounted on board a chaser which is on a relative trajectory around the target. The filter’s efficiency is proved with a simulation on a virtual target object. The results of the simulation, even though relevant to a simplified scenario, show that the estimation process is successful and can be considered a promising strategy for a correct and safe docking maneuver.

  1. Plasma sheath structure surrounding a large powered spacecraft

    Science.gov (United States)

    Mandell, M. J.; Jongeward, G. A.; Katz, I.

    1984-01-01

    Various factors determining the floating potential of a highly biased (about 4-kV) spacecraft in low earth orbit are discussed. While the common rule of thumb (90 percent negative; 10 percent positive) is usually a good guide, different biasing and grounding patterns can lead to high positive potentials. The NASCAP/LEO code can be used to predict spacecraft floating potential for complex three-dimensional spacecraft.

  2. 3D Display of Spacecraft Dynamics Using Real Telemetry

    Directory of Open Access Journals (Sweden)

    Sanguk Lee

    2002-12-01

    Full Text Available 3D display of spacecraft motion by using telemetry data received from satellite in real-time is described. Telemetry data are converted to the appropriate form for 3-D display by the real-time preprocessor. Stored playback telemetry data also can be processed for the display. 3D display of spacecraft motion by using real telemetry data provides intuitive comprehension of spacecraft dynamics.

  3. High temperature thrust chamber for spacecraft

    Science.gov (United States)

    Chazen, Melvin L. (Inventor); Mueller, Thomas J. (Inventor); Kruse, William D. (Inventor)

    1998-01-01

    A high temperature thrust chamber for spacecraft (20) is provided herein. The high temperature thrust chamber comprises a hollow body member (12) having an outer surface and an internal surface (16) defining the high temperature chamber (10). The body member (12) is made substantially of rhenium. An alloy (18) consisting of iridium and at least alloying metal selected of the group consisting of rhodium, platinum and palladium is deposited on at least a portion of the internal surface (16) of the body member (12). The iridium and the alloying metal are electrodeposited onto the body member (12). A HIP cycle is performed upon the body member (12) to cause the coating of iridium and the alloying metal to form the alloy (18) which protects the body member (12) from oxidation.

  4. Human factors issues for interstellar spacecraft

    Science.gov (United States)

    Cohen, Marc M.; Brody, Adam R.

    1991-01-01

    Developments in research on space human factors are reviewed in the context of a self-sustaining interstellar spacecraft based on the notion of traveling space settlements. Assumptions about interstellar travel are set forth addressing costs, mission durations, and the need for multigenerational space colonies. The model of human motivation by Maslow (1970) is examined and directly related to the design of space habitat architecture. Human-factors technology issues encompass the human-machine interface, crew selection and training, and the development of spaceship infrastructure during transtellar flight. A scenario for feasible instellar travel is based on a speed of 0.5c, a timeframe of about 100 yr, and an expandable multigenerational crew of about 100 members. Crew training is identified as a critical human-factors issue requiring the development of perceptual and cognitive aids such as expert systems and virtual reality.

  5. Expert system for spacecraft command and control

    Science.gov (United States)

    Wagner, R. E.

    The application of AI techniques to the automation of ground control functions in the defense satellite communication system (DSCS) is described. The aim of this effort is to lower the vulnerability of the DSCS to attack; a first step is the design of software for spacecraft maintenance and control. The benefits of automation and the need for high-level implementation are reviewed. A knowledge-based or expert approach was chosen to automate telemetry-interpretation, trend-analysis, anomaly-resolution, and status-maintenance functions now performed solely by operators; and a design concept was developed to meet the requirements of extendability, simplicity, and explicitness. Rule-based and logic-based knowledge-representation schemes, and data-driven and goal-driven control strategies are compared. The programming tools developed by the different organizations participating in the AI effort are indicated in a table.

  6. Spacecraft Status Report: 2001 Mars Odyssey

    Science.gov (United States)

    Boyles, Carole

    2012-01-01

    Fourth extension of Odyssey mission continues, with orbital science investigations and relay services for landed assets. Mitigation of aging IMU and UHF transceiver. ODY has responded to Program Office/board recommendations. All Stellar mode has been certified for flight operations and is now standard for nadir point operations on the A-side. Investigating options to mitigate aging Battery. Gradual transfer to a later LMST orbit node to shorten eclipse durations. Reduce spacecraft loads during the longer eclipses. Optimize battery performance. ODY is preparing for E5 Proposal and Planetary Science Division FY12 Senior Review activities. ODY is on track to support MSL EDL and surface operations. ODY is managing consumables in order to remain in operations until 2020.

  7. A Microwave Thruster for Spacecraft Propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Chiravalle, Vincent P [Los Alamos National Laboratory

    2012-07-23

    This presentation describes how a microwave thruster can be used for spacecraft propulsion. A microwave thruster is part of a larger class of electric propulsion devices that have higher specific impulse and lower thrust than conventional chemical rocket engines. Examples of electric propulsion devices are given in this presentation and it is shown how these devices have been used to accomplish two recent space missions. The microwave thruster is then described and it is explained how the thrust and specific impulse of the thruster can be measured. Calculations of the gas temperature and plasma properties in the microwave thruster are discussed. In addition a potential mission for the microwave thruster involving the orbit raising of a space station is explored.

  8. Dynamic interactions between ionospheric plasma and spacecraft

    Science.gov (United States)

    Snyder, David B.

    1995-01-01

    Studies of the interactions between the Space Station Freedom and ionospheric plasma led to an improved understanding of the dynamics of these interactions. Some of the issues related to developing and sustaining arcs in ionospheric conditions are considered. A technique for the estimation of the amplitude and duration of arcs is presented. The technique uses the capacitance of the system to estimate the peak current and then uses the charge stored to estimate the arc duration. As new technologies are implemented on spacecraft, new environmental compatibility issues will arise. Some of the issues related to driving dielectric surfaces with alternating current voltages are considered. The steady state charging criteria is that over an oscillation, the ion charge collected is compensated for by the electron charge collected. This tends to drive the average potential negative so that the dielectric surface is positive for only a small portion of the cycle.

  9. Application of advanced electronics to a future spacecraft computer design

    Science.gov (United States)

    Carney, P. C.

    1980-01-01

    Advancements in hardware and software technology are summarized with specific emphasis on spacecraft computer capabilities. Available state of the art technology is reviewed and candidate architectures are defined.

  10. Magellan spacecraft and memory state tracking: Lessons learned, future thoughts

    Science.gov (United States)

    Bucher, Allen W.

    1993-03-01

    Numerous studies have been dedicated to improving the two main elements of Spacecraft Mission Operations: Command and Telemetry. As a result, not much attention has been given to other tasks that can become tedious, repetitive, and error prone. One such task is Spacecraft and Memory State Tracking, the process by which the status of critical spacecraft components, parameters, and the contents of on-board memory are managed on the ground to maintain knowledge of spacecraft and memory states for future testing, anomaly investigation, and on-board memory reconstruction. The task of Spacecraft and Memory State Tracking has traditionally been a manual task allocated to Mission Operations Procedures. During nominal Mission Operations this job is tedious and error prone. Because the task is not complex and can be accomplished manually, the worth of a sophisticated software tool is often questioned. However, in the event of an anomaly which alters spacecraft components autonomously or a memory anomaly such as a corrupt memory or flight software error, an accurate ground image that can be reconstructed quickly is a priceless commodity. This study explores the process of Spacecraft and Memory State Tracking used by the Magellan Spacecraft Team highlighting its strengths as well as identifying lessons learned during the primary and extended missions, two memory anomalies, and other hardships encountered due to incomplete knowledge of spacecraft states. Ideas for future state tracking tools that require minimal user interaction and are integrated into the Ground Data System will also be discussed.

  11. Magellan spacecraft and memory state tracking: Lessons learned, future thoughts

    Science.gov (United States)

    Bucher, Allen W.

    1993-01-01

    Numerous studies have been dedicated to improving the two main elements of Spacecraft Mission Operations: Command and Telemetry. As a result, not much attention has been given to other tasks that can become tedious, repetitive, and error prone. One such task is Spacecraft and Memory State Tracking, the process by which the status of critical spacecraft components, parameters, and the contents of on-board memory are managed on the ground to maintain knowledge of spacecraft and memory states for future testing, anomaly investigation, and on-board memory reconstruction. The task of Spacecraft and Memory State Tracking has traditionally been a manual task allocated to Mission Operations Procedures. During nominal Mission Operations this job is tedious and error prone. Because the task is not complex and can be accomplished manually, the worth of a sophisticated software tool is often questioned. However, in the event of an anomaly which alters spacecraft components autonomously or a memory anomaly such as a corrupt memory or flight software error, an accurate ground image that can be reconstructed quickly is a priceless commodity. This study explores the process of Spacecraft and Memory State Tracking used by the Magellan Spacecraft Team highlighting its strengths as well as identifying lessons learned during the primary and extended missions, two memory anomalies, and other hardships encountered due to incomplete knowledge of spacecraft states. Ideas for future state tracking tools that require minimal user interaction and are integrated into the Ground Data System will also be discussed.

  12. The effect of 648 nm diode laser irradiation on second messengers in senescent human keratinocytes

    Science.gov (United States)

    Hawkins Evans, D.; Abrahamse, H.

    2009-02-01

    Background/purpose: Stress induced premature senescence (SIPS) is defined as the long-term effect of subcytotoxic stress on proliferative cell types. Cells in SIPS display differences at the level of protein expression which affect energy metabolism, defense systems, redox potential, cell morphology and transduction pathways. This study aimed to determine the effect of laser irradiation on second messengers in senescent cells and to establish if that effect can be directly linked to changes in cellular function such as cell viability or proliferation. Materials and Methods: Human keratinocyte cell cultures were modified to induce premature senescence using repeated sub-lethal stresses of 200 uM H2O2 or 5% OH every day for four days with two days recovery. SIPS was confirmed by senescence-associated β-galactosidase staining. Control conditions included normal, repeated stress of 500 uM H2O2 to induce apoptosis and 200 uM PBN as an anti-oxidant or free radical scavenger. Cells were irradiated with 1.5 J/cm2 on day 1 and 4 using a 648 nm diode laser (3.3 mW/cm2) and cellular responses were measured 1 h post irradiation. The affect on second messengers was assessed by measuring cAMP, cGMP, nitric oxide and intracellular calcium (Ca2+) while functional changes were assessed using cell morphology, ATP cell viability, LDH membrane integrity and WST-1 cell proliferation. Results: Results indicate an increase in NO and a decrease in cGMP and Ca2+ in 200 uM H2O2 irradiated cells while PBN irradiated cells showed a decrease in cAMP and an increase in ATP viability and cell proliferation. Conclusion: Laser irradiation influences cell signaling which ultimately changes the biological function of senescent cells. If laser therapy can stimulate the biological function of senescent cells it may be beneficial to conditions such as immune senescence, skin ageing, muscle atrophy, premature ageing of arteries in patients with advanced heart disease, neurodegenerative disorders and

  13. Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants. Volume 2

    Science.gov (United States)

    1996-01-01

    The National Aeronautics and Space Administration (NASA) is aware of the potential toxicological hazards to humans that might be associated with prolonged spacecraft missions. Despite major engineering advances in controlling the atmosphere within spacecraft, some contamination of the air appears inevitable. NASA has measured numerous airborne contaminants during space missions. As the missions increase in duration and complexity, ensuring the health and well-being of astronauts traveling and working in this unique environment becomes increasingly difficult. As part of its efforts to promote safe conditions aboard spacecraft, NASA requested the National Research Council (NRC) to develop guidelines for establishing spacecraft maximum allowable concentrations (SMACs) for contaminants, and to review SMACs for various space-craft contaminants to determine whether NASA's recommended exposure limits are consistent with the guidelines recommended by the subcommittee. In response to NASA's request, the NRC organized the Subcommittee on Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants within the Committee On Toxicology (COT). In the first phase of its work, the subcommittee developed the criteria and methods for preparing SMACs for spacecraft contaminants. The subcommittee's report, entitled Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants, was published in 1992. The executive summary of that report is reprinted as Appendix A of this volume. In the second phase of the study, the Subcommittee on Spacecraft Maximum Allowable Concentrations reviewed reports prepared by NASA scientists and contractors recommending SMACs for approximately 35 spacecraft contaminants. The subcommittee sought to determine whether the SMAC reports were consistent with the 1992 guidelines. Appendix B of this volume contains the SMAC reports for 12 chemical contaminants that have been reviewed for

  14. The intranuclear mobility of messenger RNA binding proteins is ATP dependent and temperature sensitive.

    Science.gov (United States)

    Calapez, Alexandre; Pereira, Henrique M; Calado, Angelo; Braga, José; Rino, José; Carvalho, Célia; Tavanez, João Paulo; Wahle, Elmar; Rosa, Agostinho C; Carmo-Fonseca, Maria

    2002-12-09

    After being released from transcription sites, messenger ribonucleoprotein particles (mRNPs) must reach the nuclear pore complexes in order to be translocated to the cytoplasm. Whether the intranuclear movement of mRNPs results largely from Brownian motion or involves molecular motors remains unknown. Here we have used quantitative photobleaching techniques to monitor the intranuclear mobility of protein components of mRNPs tagged with GFP. The results show that the diffusion coefficients of the poly(A)-binding protein II (PABP2) and the export factor TAP are significantly reduced when these proteins are bound to mRNP complexes, as compared with nonbound proteins. The data further show that the mobility of wild-type PABP2 and TAP, but not of a point mutant variant of PABP2 that fails to bind to RNA, is significantly reduced when cells are ATP depleted or incubated at 22 degrees C. Energy depletion has only minor effects on the intranuclear mobility of a 2,000-kD dextran (which corresponds approximately in size to 40S mRNP particles), suggesting that the reduced mobility of PABP2 and TAP is not caused by a general alteration of the nuclear environment. Taken together, the data suggest that the mobility of mRNPs in the living cell nucleus involves a combination of passive diffusion and ATP-dependent processes.

  15. ER/K linked GPCR-G protein fusions systematically modulate second messenger response in cells.

    Science.gov (United States)

    Malik, Rabia U; Dysthe, Matthew; Ritt, Michael; Sunahara, Roger K; Sivaramakrishnan, Sivaraj

    2017-08-10

    FRET and BRET approaches are well established for detecting ligand induced GPCR-G protein interactions in cells. Currently, FRET/BRET assays rely on co-expression of GPCR and G protein, and hence depend on the stoichiometry and expression levels of the donor and acceptor probes. On the other hand, GPCR-G protein fusions have been used extensively to understand the selectivity of GPCR signaling pathways. However, the signaling properties of fusion proteins are not consistent across GPCRs. In this study, we describe and characterize novel sensors based on the Systematic Protein Affinity Strength Modulation (SPASM) technique. Sensors consist of a GPCR and G protein tethered by an ER/K linker flanked by FRET probes. SPASM sensors are tested for the β2-, α1-, and α2- adrenergic receptors, and adenosine type 1 receptor (A 1 R), tethered to Gαs-XL, Gαi 2 , or Gαq subunits. Agonist stimulation of β2-AR and α2-AR increases FRET signal comparable to co-expressed FRET/BRET sensors. SPASM sensors also retain signaling through the endogenous G protein milieu. Importantly, ER/K linker length systematically tunes the GPCR-G protein interaction, with consequent modulation of second messenger signaling for cognate interactions. SPASM GPCR sensors serve the dual purpose of detecting agonist-induced changes in GPCR-G protein interactions, and linking these changes to downstream signaling.

  16. POEMMA (Probe Of Extreme Multi-Messenger Astrophysics) Science and Design

    Science.gov (United States)

    Olinto, Angela V.; Perkins, Jeremy S.; POEMMA Collaboration

    2018-01-01

    In this poster we describe the preliminary design of POEMMA (Probe Of Extreme Multi-Messenger Astrophysics). The two satellites flying in formation consists of an innovative Schmidt telescope design optimized for low energy threshold and large geometry factor for observations. The 4 meter mirror was designed to fit in a dual manifest launch vehicle. A novel corrector lens and fast optics are design to optimized the full field of view to 45 degrees. The large focal surface will be populated by two systems: a multi-anode PMT (MAPMT) array for fluorescence detection and a Silicon PM (SiPM) array for Cherenkov detection around the limb of the Earth. At an altitude of 525 km, the LEO orbit will have a 28.5o inclination the mission can be launched from KSC and have a mission life of 3 years with a 5 year goal. The mission will improve by orders of magnitude the observations of ultra-high energy cosmic rays above tens of EeV and search for neutrinos above tens of PeVs.

  17. Messages do diffuse faster than messengers: reconciling disparate estimates of the morphogen bicoid diffusion coefficient.

    Directory of Open Access Journals (Sweden)

    Lorena Sigaut

    2014-06-01

    Full Text Available The gradient of Bicoid (Bcd is key for the establishment of the anterior-posterior axis in Drosophila embryos. The gradient properties are compatible with the SDD model in which Bcd is synthesized at the anterior pole and then diffuses into the embryo and is degraded with a characteristic time. Within this model, the Bcd diffusion coefficient is critical to set the timescale of gradient formation. This coefficient has been measured using two optical techniques, Fluorescence Recovery After Photobleaching (FRAP and Fluorescence Correlation Spectroscopy (FCS, obtaining estimates in which the FCS value is an order of magnitude larger than the FRAP one. This discrepancy raises the following questions: which estimate is "correct''; what is the reason for the disparity; and can the SDD model explain Bcd gradient formation within the experimentally observed times? In this paper, we use a simple biophysical model in which Bcd diffuses and interacts with binding sites to show that both the FRAP and the FCS estimates may be correct and compatible with the observed timescale of gradient formation. The discrepancy arises from the fact that FCS and FRAP report on different effective (concentration dependent diffusion coefficients, one of which describes the spreading rate of the individual Bcd molecules (the messengers and the other one that of their concentration (the message. The latter is the one that is more relevant for the gradient establishment and is compatible with its formation within the experimentally observed times.

  18. Nitric Oxide as a Unique Bioactive Signaling Messenger in Physiology and Pathophysiology

    Directory of Open Access Journals (Sweden)

    Tuteja Narendra

    2004-01-01

    Full Text Available Nitric oxide (NO is an intra- and extracellular messenger that mediates diverse signaling pathways in target cells and is known to play an important role in many physiological processes including neuronal signaling, immune response, inflammatory response, modulation of ion channels, phagocytic defense mechanism, penile erection, and cardiovascular homeostasis and its decompensation in atherogenesis. Recent studies have also revealed a role for NO as signaling molecule in plant, as it activates various defense genes and acts as developmental regulator. In plants, NO can also be produced by nitrate reductase. NO can operate through posttranslational modification of proteins (nitrosylation. NO is also a causative agent in various pathophysiological abnormalities. One of the very important systems, the cardiovascular system, is affected by NO production, as this bioactive molecule is involved in the regulation of cardiovascular motor tone, modulation of myocardial contractivity, control of cell proliferation, and inhibition of platelet activation, aggregation, and adhesion. The prime source of NO in the cardiovascular system is endothelial NO synthase, which is tightly regulated with respect to activity and localization. The inhibition of chronic NO synthesis leads to neurogenic and arterial hypertensions, which later contribute to development of myocardial fibrosis. Overall, the modulation of NO synthesis is associated with hypertension. This review briefly describes the physiology of NO, its synthesis, catabolism, and targeting, the mechanism of NO action, and the pharmacological role of NO with special reference to its essential role in hypertension.

  19. Hypophosphorylated ASF/SF2 binds TAP and is present in messenger ribonucleoproteins.

    Science.gov (United States)

    Lai, Ming-Chih; Tarn, Woan-Yuh

    2004-07-23

    Serine/arginine-rich proteins (SR proteins) function in precursor mRNA (pre-mRNA) splicing and may also act as adaptors for mRNA export. SR proteins are dynamically phosphorylated in their RS domain, and differential phosphorylation modulates their splicing activity and subcellular localization. In this study, we investigated the influence of phosphorylation on the function of SR proteins in events occurring during mRNA maturation. Immunoprecipitation experiments showed that the mRNA export receptor TAP associates preferentially with the hypophosphorylated form of shuttling SR proteins, including ASF/SF2. Overexpression of ASF induced subnuclear relocalization of TAP to SR protein-enriched nuclear speckles, suggesting their interaction in vivo. Moreover, the ASF found in a nucleoplasmic fraction rich in heterogeneous nuclear ribonucleoprotein (hnRNP) complexes is hyperphosphorylated, whereas mature messenger RNP (mRNP)-bound ASF is hypophosphorylated. Therefore, hypophosphorylation of ASF in mRNPs coincides with its higher affinity for TAP, suggesting that dephosphorylation of ASF promotes both its incorporation into mRNPs and recruitment of TAP for mRNA export. Thus, the phosphorylation state of RS domains may modulate the function of mammalian shuttling SR proteins during mRNA maturation or export.

  20. Chemical Heterogeneity on Mercury's Surface Revealed by the MESSENGER X-ray Spectrometer

    Science.gov (United States)

    Weider, Shoshana Z.; Nittler, Larry R.; Starr, Richard D.; McCoy, Timothy J.; Stockstill-Cahill, Karen R.; Byrne, Paul K.; Denevi, Brett W.; Head, James W.; Solomon, Sean C.

    2012-01-01

    We present the analysis of 205 spatially resolved measurements of the surfacecomposition of Mercury from MESSENGERs X-Ray Spectrometer. The surfacefootprints of these measurements are categorized according to geological terrain. Northernsmooth plains deposits and the plains interior to the Caloris basin differ compositionallyfrom older terrain on Mercury. The older terrain generally has higher MgSi, SSi, andCaSi ratios, and a lower AlSi ratio than the smooth plains. Mercurys surface mineralogyis likely dominated by high-Mg mafic minerals (e.g., enstatite), plagioclase feldspar, andlesser amounts of Ca, Mg, andor Fe sulfides (e.g., oldhamite). The compositionaldifference between the volcanic smooth plains and the older terrain reflects differentabundances of these minerals and points to the crystallization of the smooth plains from amore chemically evolved magma source. High-degree partial melts of enstatite chondritematerial provide a generally good compositional and mineralogical match for much ofthe surface of Mercury. An exception is Fe, for which the low surface abundance onMercury is still higher than that of melts from enstatite chondrites and may indicate anexogenous contribution from meteoroid impacts.

  1. Involvement of second messengers in regulation of the low-density lipoprotein receptor gene

    Energy Technology Data Exchange (ETDEWEB)

    Auwerx, J.H. (Leuven Univ. (Belgium). ECHEM Labs.); Chait, A.; Wolfbauer, G.; Deeb, S.S. (Washington Univ., Seattle, WA (USA). Dept. of Medicine)

    1989-06-01

    Transcription of the low-density lipoprotein receptor (LDL-R) gene in the human monocytic leukemic cell line THP-1 and in the human hepatocarcinoma cell line Hep-G2 is regulated by second messengers of the diacylglycerol-protein kinase C (DAG-PKC), inositol 1,4,5-triphosphate-Ca/sup 2+/, and cyclic AMP pathways. Exogeneous phospholipase C (which releases DAG and inositol 1,4,5-triphosphate), PKC activators (phorbol esters and DAG), Ca/sup 2+/ ionophores, and a cyclic AMP analog all transiently induced accumulation of LDL-R mRNA. The effects of these three signal-transducing pathways were to a large extend additive. Furthermore, PKC stimulation effected an increase in LDL binding, which suggested that the increase in LDL-R mRNA resulted in an increase in functional cell surface receptor activity. These results suggest that uptake of cholesterol by these cells is under control of both intracellular cholesterol levels and external signals.

  2. Aberrant herpesvirus-induced polyadenylation correlates with cellular messenger RNA destruction.

    Directory of Open Access Journals (Sweden)

    Yeon J Lee

    2009-05-01

    Full Text Available Regulation of messenger RNA (mRNA stability plays critical roles in controlling gene expression, ensuring transcript fidelity, and allowing cells to respond to environmental cues. Unregulated enhancement of mRNA turnover could therefore dampen cellular responses to such signals. Indeed, several herpesviruses instigate widespread destruction of cellular mRNAs to block host gene expression and evade immune detection. Kaposi's sarcoma-associated herpesvirus (KSHV promotes this phenotype via the activity of its viral SOX protein, although the mechanism of SOX-induced mRNA turnover has remained unknown, given its apparent lack of intrinsic ribonuclease activity. Here, we report that KSHV SOX stimulates cellular transcriptome turnover via a unique mechanism involving aberrant polyadenylation. Transcripts in SOX-expressing cells exhibit extended poly(A polymerase II-generated poly(A tails and polyadenylation-linked mRNA turnover. SOX-induced polyadenylation changes correlate with its RNA turnover function, and inhibition of poly(A tail formation blocks SOX activity. Both nuclear and cytoplasmic poly(A binding proteins are critical cellular cofactors for SOX function, the latter of which undergoes striking nuclear relocalization by SOX. SOX-induced mRNA turnover therefore represents both a novel mechanism of host shutoff as well as a new model system to probe the regulation of poly(A tail-stimulated mRNA turnover in mammalian cells.

  3. Ames stereo pipeline-derived digital terrain models of Mercury from MESSENGER stereo imaging

    Science.gov (United States)

    Fassett, Caleb I.

    2016-12-01

    In this study, 96 digital terrain models (DTMs) of Mercury were created using the Ames Stereo Pipeline, using 1456 pairs of stereo images from the Mercury Dual Imaging System instrument on MESSENGER. Although these DTMs cover only 1% of the surface of Mercury, they enable three-dimensional characterization of landforms at horizontal resolutions of 50-250 m/pixel and vertical accuracy of tens of meters. This is valuable in regions where the more precise measurements from the Mercury Laser Altimeter (MLA) are sparse. MLA measurements nonetheless provide an important geodetic framework for the derived stereo products. These DTMs, which are publicly released in conjunction with this paper, reveal topography of features at relatively small scales, including craters, graben, hollows, pits, scarps, and wrinkle ridges. Measurements from these data indicate that: (1) hollows have a median depth of 32 m, in basic agreement with earlier shadow measurement, (2) some of the deep pits (up to 4 km deep) that are interpreted to form via volcanic processes on Mercury have surrounding rims or rises, but others do not, and (3) some pits have two or more distinct, low-lying interior minima that could represent multiple vents.

  4. Messenger RNA- versus retrovirus-based induced pluripotent stem cell reprogramming strategies: analysis of genomic integrity.

    Science.gov (United States)

    Steichen, Clara; Luce, Eléanor; Maluenda, Jérôme; Tosca, Lucie; Moreno-Gimeno, Inmaculada; Desterke, Christophe; Dianat, Noushin; Goulinet-Mainot, Sylvie; Awan-Toor, Sarah; Burks, Deborah; Marie, Joëlle; Weber, Anne; Tachdjian, Gérard; Melki, Judith; Dubart-Kupperschmitt, Anne

    2014-06-01

    The use of synthetic messenger RNAs to generate human induced pluripotent stem cells (iPSCs) is particularly appealing for potential regenerative medicine applications, because it overcomes the common drawbacks of DNA-based or virus-based reprogramming strategies, including transgene integration in particular. We compared the genomic integrity of mRNA-derived iPSCs with that of retrovirus-derived iPSCs generated in strictly comparable conditions, by single-nucleotide polymorphism (SNP) and copy number variation (CNV) analyses. We showed that mRNA-derived iPSCs do not differ significantly from the parental fibroblasts in SNP analysis, whereas retrovirus-derived iPSCs do. We found that the number of CNVs seemed independent of the reprogramming method, instead appearing to be clone-dependent. Furthermore, differentiation studies indicated that mRNA-derived iPSCs differentiated efficiently into hepatoblasts and that these cells did not load additional CNVs during differentiation. The integration-free hepatoblasts that were generated constitute a new tool for the study of diseased hepatocytes derived from patients' iPSCs and their use in the context of stem cell-derived hepatocyte transplantation. Our findings also highlight the need to conduct careful studies on genome integrity for the selection of iPSC lines before using them for further applications. ©AlphaMed Press.

  5. LIN28 binds messenger RNAs at GGAGA motifs and regulates splicing factor abundance.

    Science.gov (United States)

    Wilbert, Melissa L; Huelga, Stephanie C; Kapeli, Katannya; Stark, Thomas J; Liang, Tiffany Y; Chen, Stella X; Yan, Bernice Y; Nathanson, Jason L; Hutt, Kasey R; Lovci, Michael T; Kazan, Hilal; Vu, Anthony Q; Massirer, Katlin B; Morris, Quaid; Hoon, Shawn; Yeo, Gene W

    2012-10-26

    LIN28 is a conserved RNA-binding protein implicated in pluripotency, reprogramming, and oncogenesis. It was previously shown to act primarily by blocking let-7 microRNA (miRNA) biogenesis, but here we elucidate distinct roles of LIN28 regulation via its direct messenger RNA (mRNA) targets. Through crosslinking and immunoprecipitation coupled with high-throughput sequencing (CLIP-seq) in human embryonic stem cells and somatic cells expressing exogenous LIN28, we have defined discrete LIN28-binding sites in a quarter of human transcripts. These sites revealed that LIN28 binds to GGAGA sequences enriched within loop structures in mRNAs, reminiscent of its interaction with let-7 miRNA precursors. Among LIN28 mRNA targets, we found evidence for LIN28 autoregulation and also direct but differing effects on the protein abundance of splicing regulators in somatic and pluripotent stem cells. Splicing-sensitive microarrays demonstrated that exogenous LIN28 expression causes widespread downstream alternative splicing changes. These findings identify important regulatory functions of LIN28 via direct mRNA interactions. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Multi-messenger Light Curves from Gamma-Ray Bursts in the Internal Shock Model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, Columbus, OH 43210 (United States); Heinze, Jonas; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, D-15738 Zeuthen (Germany); Murase, Kohta, E-mail: bustamanteramirez.1@osu.edu, E-mail: walter.winter@desy.de, E-mail: jonas.heinze@desy.de, E-mail: murase@psu.edu [Center for Particle and Gravitational Astrophysics, The Pennsylvania State University, University Park, PA16802 (United States)

    2017-03-01

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma-rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure can be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  7. Multi-messenger light curves from gamma-ray bursts in the internal shock model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Ohio State Univ., Columbus, OH (United States). Center for Cosmology and AstroParticle Physics (CCAPP); Ohio State Univ., Columbus, OH (United States). Dept. of Physics; Murase, Kohta [Pennsylvania State Univ., University Park, PA (United States). Center for Particle and Gravitational Astrophysics; Pennsylvania State Univ., University Park, PA (United States). Dept. of Astronomy and Astrophysics; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2016-06-15

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure tend to be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  8. Multi-messenger studies of compact binary mergers in the in the ngVLA era

    Science.gov (United States)

    Corsi, Alessandra

    2018-01-01

    We explore some of the scientific opportunities that the next generation Very Large Array (ngVLA) will open in the field of multi-messenger time-domain astronomy. We focus on compact binary mergers, golden astrophysical targets of ground-based gravitational wave (GW) detectors such as advanced LIGO. A decade from now, a large number of these mergers is likely to be discovered by a world-wide network of GW detectors. We discuss how a radio array with 10 times the sensitivity of the current Karl G. Jansky VLA and 10 times the resolution, would enable resolved radio continuum studies of binary merger hosts, probing regions of the galaxy undergoing star formation (which can be heavily obscured by dust and gas), AGN components, and mapping the offset distribution of the mergers with respect to the host galaxy light. For compact binary mergers containing at least one neutron star (NS), from which electromagnetic counterparts are expected to exist, we show how the ngVLA would enable direct size measurements of the relativistic merger ejecta and probe, for the first time directly, their dynamics.

  9. eIF3 targets cell-proliferation messenger RNAs for translational activation or repression.

    Science.gov (United States)

    Lee, Amy S Y; Kranzusch, Philip J; Cate, Jamie H D

    2015-06-04

    Regulation of protein synthesis is fundamental for all aspects of eukaryotic biology by controlling development, homeostasis and stress responses. The 13-subunit, 800-kilodalton eukaryotic initiation factor 3 (eIF3) organizes initiation factor and ribosome interactions required for productive translation. However, current understanding of eIF3 function does not explain genetic evidence correlating eIF3 deregulation with tissue-specific cancers and developmental defects. Here we report the genome-wide discovery of human transcripts that interact with eIF3 using photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP). eIF3 binds to a highly specific program of messenger RNAs involved in cell growth control processes, including cell cycling, differentiation and apoptosis, via the mRNA 5' untranslated region. Surprisingly, functional analysis of the interaction between eIF3 and two mRNAs encoding the cell proliferation regulators c-JUN and BTG1 reveals that eIF3 uses different modes of RNA stem-loop binding to exert either translational activation or repression. Our findings illuminate a new role for eIF3 in governing a specialized repertoire of gene expression and suggest that binding of eIF3 to specific mRNAs could be targeted to control carcinogenesis.

  10. Disturbances in lipid second messengers generation by stimulated blood lymphocytes in breast cancer

    Directory of Open Access Journals (Sweden)

    Galstyan H. M.

    2011-10-01

    Full Text Available Aim. The main objective of this study was the comparative investigation of diverse lipid second messenger (LSM generation by human peripheral blood lymphocytes (HPBL at different (5, 10, 30 and 60 s time points of cell co-stimulation by anti-CD3 and anti-CD28 monoclonal antibodies in norm and breast cancer (BC. Methods. Ficoll-Hypaque gradient centrifugation. Results. The data obtained indicate that some mechanisms of LSM generation/utilization in stimulated crude HPBL were significantly altered in BC compared to norm. Particularly, the reliable generation of arachidonyl-1,2-diacylglycerol (1,2-DAG at the initial step (5 s of cell stimulation observed in norm was depressed in BC and reached the value below the basal level in unstimulated cells. It is important that the disturbances in 1,2-DAG formation in HPBL obtained from patients with BC were identical with those observed earlier in other forms of cancer. Conclusions. We conclude that the regularities revealed are common characteristics for all the types of malignancy studied and can be used as additional testing parameters for cancer definition and individual correction of the chemotherapy programs for disease treatment

  11. Unusual stability of messenger RNA in snake venom reveals gene expression dynamics of venom replenishment.

    Directory of Open Access Journals (Sweden)

    Rachel B Currier

    Full Text Available Venom is a critical evolutionary innovation enabling venomous snakes to become successful limbless predators; it is therefore vital that venomous snakes possess a highly efficient venom production and delivery system to maintain their predatory arsenal. Here, we exploit the unusual stability of messenger RNA in venom to conduct, for the first time, quantitative PCR to characterise the dynamics of gene expression of newly synthesised venom proteins following venom depletion. Quantitative PCR directly from venom enables real-time dynamic studies of gene expression in the same animals because it circumvents the conventional requirement to sacrifice snakes to extract mRNA from dissected venom glands. Using qPCR and proteomic analysis, we show that gene expression and protein re-synthesis triggered by venom expulsion peaks between days 3-7 of the cycle of venom replenishment, with different protein families expressed in parallel. We demonstrate that venom re-synthesis occurs very rapidly following depletion of venom stores, presumably to ensure venomous snakes retain their ability to efficiently predate and remain defended from predators. The stability of mRNA in venom is biologically fascinating, and could significantly empower venom research by expanding opportunities to produce transcriptomes from historical venom stocks and rare or endangered venomous species, for new therapeutic, diagnostic and evolutionary studies.

  12. Messenger RNA profiling for forensic body fluid identification: research and applications.

    Science.gov (United States)

    Wang, Zheng; Zhang, Su-hua; Di, Zhou; Zhao, Shu-min; Li, Cheng-tao

    2013-10-01

    Identifying the origin of body fluids left at a crime scene can give a significant insight into crime scene reconstruction by supporting a link between sample donors and actual criminal acts. However, the conventional body fluid identification methods are prone to various limitations, such as time consumption, intensive labor, nonparallel manner, varying degrees of sensitivity and limited specificity. Recently, the analysis of cell-specific messenger RNA expression (mRNA profiling) has been proposed to supplant conventional methods for body fluid identification. Since 2011, the collaborative exercises have been organized by the European DNA Profiling Group (EDNAP) in order to evaluate the robustness and reproducibility of mRNA profiling for body fluid identification. The major advantages of mRNA profiling, compared to the conventional methods, include higher sensitivity, greater specificity, the ability of detecting several body fluids in one multiplex reaction, and compatibility with current DNA extraction and analysis procedure. In the current review, we provided an overview of the present knowledge and detection methodologies of mRNA profiling for forensic body fluid identification and discussed its possible practical application to forensic casework.

  13. Role of WhatsApp Messenger in the Laboratory Management System: A Boon to Communication.

    Science.gov (United States)

    Dorwal, Pranav; Sachdev, Ritesh; Gautam, Dheeraj; Jain, Dharmendra; Sharma, Pooja; Tiwari, Assem Kumar; Raina, Vimarsh

    2016-01-01

    The revolution of internet and specifically mobile internet has occurred at a blinding pace over the last decade. With the advent of smart phones, the hand held device has become much more than a medium of voice calling. Healthcare has been catching up with the digital revolution in the form of Hospital Information System and Laboratory Information System. However, the advent of instant messaging services, which are abundantly used by the youth, can be used to improve communication and coordination among the various stake holders in the healthcare sector. We have tried to look at the impact of using the WhatsApp messenger service in the laboratory management system, by forming multiple groups of the various subsections of the laboratory. A total of 35 members used this service for a period of 3 months and their response was taken on a scale of 1 to 10. There was significant improvement in the communication in the form of sharing photographic evidence, information about accidents, critical alerts, duty rosters, academic activities and getting directives from seniors. There was also some increase in the load of adding information to the application and disturbance in the routine activities; but the benefits far outweighed the minor hassles. We thereby suggest and foresee another communication revolution which will change the way information is shared in a healthcare sector, with hospital specific dedicated apps.

  14. Microbial diversity on spacecraft and in spacecraft assembly and testing facilities

    Science.gov (United States)

    Rettberg, P.; Nellen, J.; Fritze, D.; Verbarg, S.; Stackebrandt, E.; Kminek, G.

    Planetary protection measures are necessary for all space flight missions involved with life detection and or sample return procedures to avoid the contamination of critical spacecraft hardware components with terrestrial organisms Spacecraft are assembled in clean rooms under defined and controlled environmental conditions These conditions might be considered as extreme with respect to controlled air circulation low relative humidity moderately high constant temperature and low nutrient conditions and represent a special artificial environment for microorganisms In the ESA-Project MiDiv the bioburden and the microbial diversity of three different spacecraft assembly and testing facilities has been investigated in periods where the facilities have been in full operation with the assembly and test of European satellites For the selected satellite missions SMART-1 and ROSETTA however no strict planetary protection measures like those required for a landing mission on Mars COSPAR Planetary Protection Category IV have been necessary and taken into consideration The result of this investigation therefore reflects the normal microbial conditions in standard class 100 000 clean rooms used by employees without any special training in planetary protection The investigation in the MiDiv project was restricted to so-called cultivable microorganisms in particular to those microorganisms that are able to grow under the selected conditions The analysis of the samples included cultivation on different media at different pH values and

  15. Study of messenger RNA inactivation and protein degradation in an Escherichia coli cell-free expression system

    Directory of Open Access Journals (Sweden)

    Noireaux Vincent

    2010-07-01

    Full Text Available Abstract Background A large amount of recombinant proteins can be synthesized in a few hours with Escherichia coli cell-free expression systems based on bacteriophage transcription. These cytoplasmic extracts are used in many applications that require large-scale protein production such as proteomics and high throughput techniques. In recent years, cell-free systems have also been used to engineer complex informational processes. These works, however, have been limited by the current available cell-free systems, which are not well adapted to these types of studies. In particular, no method has been proposed to increase the mRNA inactivation rate and the protein degradation rate in cell-free reactions. The construction of in vitro informational processes with interesting dynamics requires a balance between mRNA and protein synthesis (the source, and mRNA inactivation and protein degradation (the sink. Results Two quantitative studies are presented to characterize and to increase the global mRNA inactivation rate, and to accelerate the degradation of the synthesized proteins in an E. coli cell-free expression system driven by the endogenous RNA polymerase and sigma factor 70. The E. coli mRNA interferase MazF was used to increase and to adjust the mRNA inactivation rate of the Firefly luciferase (Luc and of the enhanced green fluorescent protein (eGFP. Peptide tags specific to the endogenous E. coli AAA + proteases were used to induce and to adjust the protein degradation rate of eGFP. Messenger RNA inactivation rate, protein degradation rate, maturation time of Luc and eGFP were measured. Conclusions The global mRNA turnover and the protein degradation rate can be accelerated and tuned in a biologically relevant range in a cell-free reaction with quantitative procedures easy to implement. These features broaden the capabilities of cell-free systems with a better control of gene expression. This cell-free extract could find some applications in

  16. Reflectance and Emissivity Spectra of Graphite as Potential Darkening Agent for Mercury from the UV to the TIR and its Comparison to Remote Sensing Measurements from MESSENGER and MERTIS on BepiColombo

    Science.gov (United States)

    Maturilli, A.; Helbert, J.; D'Amore, M.; Ferrari, S.; Hiesinger, H.

    2016-12-01

    For long time Mercury was considered a planet very similar to the Moon. Both are small rocky bodies in the inner solar system with thin exospheres and no large scale traces of recent geological activity. However Mercury's surface reflects much less sunlight than the Moon. Trying to explain the reasons for this difference, significant abundances of iron and titanium (and their oxides) were proposed for the Hermean surface. But the NASA MESSENGER instruments found only small abundances of iron, confirming earlier ground-based spectroscopy observations, and virtually no titanium. Therefore neither of the elements can account for this diversity. New analysis of MESSENGER data acquired for the darkest regions of Mercury's surface suggest that the unknown darkening material could be carbon, in particular as the mineral graphite (Peplowski et al., 2016) whose abundance in the darker regions is predicted to be 1 to 3 wt% higher than the surroundings. At the Planetary Spectroscopy Laboratory (PSL) of the Institute of Planetary Research (DLR, Berlin) we measured reflectance spectra for several phase angles of graphite, from UV to TIR spectral range (0.2 to 20 µm). Samples have been measured fresh and then after successive steps of heating at 400°C in vacuum for 8 hours. Following the same procedure, reflectance spectra of Komatiite (chosen as Mercury surface simulant, after Maturilli et al., 2014) was measured alone and mixed with few % of graphite to reproduce the results from Peplowski et al (2016). The results from this experiment can be compared to the data acquired from the MDIS and the MASCS instrument onboard the NASA MESSENGER mission. The same set of samples has been measured in emissivity, in vacuum (board of the ESA BepiColombo Mercury Planetary Orbiter (MPO) scheduled for 2018.

  17. Handling Qualities of a Capsule Spacecraft During Atmospheric Entry

    Science.gov (United States)

    Bilimoria, Karl D.; Mueller, Eric R.

    2010-01-01

    A piloted simulation was conducted to study handling qualities for capsule spacecraft entering the Earth s atmosphere. Eight evaluation pilots, including six pilot astronauts, provided Cooper-Harper ratings, workload ratings, and qualitative comments. The simulation began after descending through the atmospheric entry interface point and continued until the drogue parachutes deployed. There were two categories of piloting tasks, both of which required bank angle control. In one task category, the pilot followed a closed-loop bank angle command computed by the backup guidance system to manage g-loads during entry. In the other task category, the pilot used intuitive rules to determine the desired bank angle independently, based on an open-loop schedule of vertical speed, Mach, and total energy specified at several range-to-target gates along the entry trajectory. Pilots were able to accurately track the bank angle guidance commands and steered the capsule toward the recovery site with essentially the same range error as the benchmark autopilot trajectory albeit with substantially higher propellant usage, and the handling qualities for this task were satisfactory. Another key result was that the complex piloting task of atmospheric entry could be performed satisfactorily, even in the presence of large dispersions, by controlling bank angle to follow a simple open-loop schedule.

  18. Modeling Methodologies For Microvibration- Related Analyses Of Spacecraft Structrues

    Science.gov (United States)

    Remedia, M.; Aglietti, G. S.; Zhang, Z.; Le Page, B.; Richardson, G.

    2012-07-01

    Driven by the increasingly stringent stability requirement of some modern payloads (e.g. the new generations of optical instruments) the issue of accurate spacecraft micro-vibration modeling has grown increasingly important. In this context micro-vibrations are low level mechanical disturbances occurring at frequencies from a few Hertz up to 1000 Hz. As the frequency content of these phenomena extends beyond the first few modal frequencies, FEA predictions become less accurate and alternative methods have to be considered. Other modeling and analysis techniques have been investigated and applied to vibration problems (Stochastic Finite Element Method (e.g. Monte Carlo Simulation), Statistical Energy Analysis (well-established method for high frequency ranges) and the Hybrid FE-SEA), with the aim of investigating medium and high frequency behavior. This work is part of a project whose aim is to establish appropriate procedures for the modeling and analysis of micro-vibration and validate these procedures against experimental data. All the methods cited above are implemented in this study and compared with experimental results, in order to assess the performance of the various methodologies for micro-vibration problems, covering the whole frequency range up to 1000 Hz. Some comparisons between experimental and computational results are performed using the MAC. Some other analyses, like linearity, reciprocity or effect of the harness are also described. The bench work model that has provided the experimental data is the satellite platform SSTL 300 and this paper outlines these related test campaigns.

  19. A Survey of LIDAR Technology and Its Use in Spacecraft Relative Navigation

    Science.gov (United States)

    Christian, John A.; Cryan, Scott P.

    2013-01-01

    This paper provides a survey of modern LIght Detection And Ranging (LIDAR) sensors from a perspective of how they can be used for spacecraft relative navigation. In addition to LIDAR technology commonly used in space applications today (e.g. scanning, flash), this paper reviews emerging LIDAR technologies gaining traction in other non-aerospace fields. The discussion will include an overview of sensor operating principles and specific pros/cons for each type of LIDAR. This paper provides a comprehensive review of LIDAR technology as applied specifically to spacecraft relative navigation. HE problem of orbital rendezvous and docking has been a consistent challenge for complex space missions since before the Gemini 8 spacecraft performed the first successful on-orbit docking of two spacecraft in 1966. Over the years, a great deal of effort has been devoted to advancing technology associated with all aspects of the rendezvous, proximity operations, and docking (RPOD) flight phase. After years of perfecting the art of crewed rendezvous with the Gemini, Apollo, and Space Shuttle programs, NASA began investigating the problem of autonomous rendezvous and docking (AR&D) to support a host of different mission applications. Some of these applications include autonomous resupply of the International Space Station (ISS), robotic servicing/refueling of existing orbital assets, and on-orbit assembly.1 The push towards a robust AR&D capability has led to an intensified interest in a number of different sensors capable of providing insight into the relative state of two spacecraft. The present work focuses on exploring the state-of-the-art in one of these sensors - LIght Detection And Ranging (LIDAR) sensors. It should be noted that the military community frequently uses the acronym LADAR (LAser Detection And Ranging) to refer to what this paper calls LIDARs. A LIDAR is an active remote sensing device that is typically used in space applications to obtain the range to one or more

  20. Rockets and spacecraft: Sine qua non of space science

    Science.gov (United States)

    1980-01-01

    The evolution of the national launch vehicle stable is presented along with lists of launch vehicles used in NASA programs. A partial list of spacecraft used throughout the world is also given. Scientific spacecraft costs are presented along with an historial overview of project development and funding in NASA.

  1. Low-Impact Mating System for Docking Spacecraft

    Science.gov (United States)

    Lewis, James L.; Robertson, Brandan; Carroll, Monty B.; Le, Thang; Morales, Ray

    2008-01-01

    A document describes a low-impact mating system suitable for both docking (mating of two free-flying spacecraft) and berthing (in which a robot arm in one spacecraft positions an object for mating with either spacecraft). The low-impact mating system is fully androgynous: it mates with a copy of itself, i.e., all spacecraft and other objects to be mated are to be equipped with identical copies of the system. This aspect of the design helps to minimize the number of unique parts and to standardize and facilitate mating operations. The system includes a closed-loop feedback control subsystem that actively accommodates misalignments between mating spacecraft, thereby attenuating spacecraft dynamics and mitigating the need for precise advance positioning of the spacecraft. The operational characteristics of the mating system can be easily configured in software, during operation, to enable mating of spacecraft having various masses, center-of-gravity offsets, and closing velocities. The system design provides multi-fault tolerance for critical operations: for example, to ensure unmating at a critical time, a redundant unlatching mechanism and two independent pyrotechnic release subsystems are included.

  2. Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants, Volume 5

    National Research Council Canada - National Science Library

    Committee on Spacecraft Exposure Guidelines; Board on Environmental Studies and Toxicology; Committee on Toxicology

    2008-01-01

    ... requested the National Research Council (NRC) to develop guidelines for establishing spacecraft maximum allowable concentrations (SMACs) for contaminants and to review SMACs for various spacecraft contaminants to determine whether NASA's recommended exposure limits are consistent with the guidelines recommended by the committee. In response to this...

  3. Spacecraft maximum allowable concentrations for selected airborne contaminants, volume 1

    Science.gov (United States)

    1994-01-01

    As part of its efforts to promote safe conditions aboard spacecraft, NASA requested the National Research Council (NRC) to develop guidelines for establishing spacecraft maximum allowable concentrations (SMAC's) for contaminants, and to review SMAC's for various spacecraft contaminants to determine whether NASA's recommended exposure limits are consistent with the guidelines recommended by the subcommittee. In response to NASA's request, the NRC organized the Subcommittee on Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants within the Committee on Toxicology (COT). In the first phase of its work, the subcommittee developed the criteria and methods for preparing SMAC's for spacecraft contaminants. The subcommittee's report, entitled Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants, was published in 1992. The executive summary of that report is reprinted as Appendix A of this volume. In the second phase of the study, the Subcommittee on Spacecraft Maximum Allowable Concentrations reviewed reports prepared by NASA scientists and contractors recommending SMAC's for 35 spacecraft contaminants. The subcommittee sought to determine whether the SMAC reports were consistent with the 1992 guidelines. Appendix B of this volume contains the first 11 SMAC reports that have been reviewed for their application of the guidelines developed in the first phase of this activity and approved by the subcommittee.

  4. Precise Relative Positioning of Formation Flying Spacecraft using GPS

    NARCIS (Netherlands)

    Kroes, R.

    2006-01-01

    Spacecraft formation flying is considered as a key technology for advanced space missions. Compared to large individual spacecraft, the distribution of sensor systems amongst multiple platforms offers improved flexibility, shorter times to mission, and the prospect of being more cost effective.

  5. A Comparison of Learning Technologies for Teaching Spacecraft Software Development

    Science.gov (United States)

    Straub, Jeremy

    2014-01-01

    The development of software for spacecraft represents a particular challenge and is, in many ways, a worst case scenario from a design perspective. Spacecraft software must be "bulletproof" and operate for extended periods of time without user intervention. If the software fails, it cannot be manually serviced. Software failure may…

  6. Synaptic plasticity in the medial vestibular nuclei: role of glutamate receptors and retrograde messengers in rat brainstem slices.

    Science.gov (United States)

    Grassi, S; Pettorossi, V E

    2001-08-01

    The analysis of cellular-molecular events mediating synaptic plasticity within vestibular nuclei is an attempt to explain the mechanisms underlying vestibular plasticity phenomena. The present review is meant to illustrate the main results, obtained in vitro, on the mechanisms underlying long-term changes in synaptic strength within the medial vestibular nuclei. The synaptic plasticity phenomena taking place at the level of vestibular nuclei could be useful for adapting and consolidating the efficacy of vestibular neuron responsiveness to environmental requirements, as during visuo-vestibular recalibration and vestibular compensation. Following a general introduction on the most salient features of vestibular compensation and visuo-vestibular adaptation, which are two plastic events involving neuronal circuitry within the medial vestibular nuclei, the second and third sections describe the results from rat brainstem slice studies, demonstrating the possibility to induce long-term potentiation and depression in the medial vestibular nuclei, following high frequency stimulation of the primary vestibular afferents. In particular the mechanisms sustaining the induction and expression of vestibular long-term potentiation and depression, such as the role of various glutamate receptors and retrograde messengers have been described. The relevant role of the interaction between the platelet-activating factor, acting as a retrograde messenger, and the presynaptic metabotropic glutamate receptors, in determining the full expression of vestibular long-term potentiation is also underlined. In addition, the mechanisms involved in vestibular long-term potentiation have been compared with those leading to long-term potentiation in the hippocampus to emphasize the most significant differences emerging from vestibular studies. The fourth part, describes recent results demonstrating the essential role of nitric oxide, another retrograde messenger, in the induction of vestibular

  7. WhatsApp messenger as a tool to supplement medical education for medical students on clinical attachment

    OpenAIRE

    Raiman, Lewis; Antbring, Richard; Mahmood, Asad

    2017-01-01

    Background Instant messaging applications have the potential to improve and facilitate communication between hospital doctors and students, hence generating and improving learning opportunities. This study aims to demonstrate the feasibility and acceptability of instant messaging communication to supplement medical education for medical students whilst on clinical attachment. Methods A total of 6 WhatsApp Messenger (WhatsApp Inc.) groups were created for medical students on clinical attachmen...

  8. Quaternion normalization in spacecraft attitude determination

    Science.gov (United States)

    Deutschmann, J.; Markley, F. L.; Bar-Itzhack, Itzhack Y.

    1993-01-01

    Attitude determination of spacecraft usually utilizes vector measurements such as Sun, center of Earth, star, and magnetic field direction to update the quaternion which determines the spacecraft orientation with respect to some reference coordinates in the three dimensional space. These measurements are usually processed by an extended Kalman filter (EKF) which yields an estimate of the attitude quaternion. Two EKF versions for quaternion estimation were presented in the literature; namely, the multiplicative EKF (MEKF) and the additive EKF (AEKF). In the multiplicative EKF, it is assumed that the error between the correct quaternion and its a-priori estimate is, by itself, a quaternion that represents the rotation necessary to bring the attitude which corresponds to the a-priori estimate of the quaternion into coincidence with the correct attitude. The EKF basically estimates this quotient quaternion and then the updated quaternion estimate is obtained by the product of the a-priori quaternion estimate and the estimate of the difference quaternion. In the additive EKF, it is assumed that the error between the a-priori quaternion estimate and the correct one is an algebraic difference between two four-tuple elements and thus the EKF is set to estimate this difference. The updated quaternion is then computed by adding the estimate of the difference to the a-priori quaternion estimate. If the quaternion estimate converges to the correct quaternion, then, naturally, the quaternion estimate has unity norm. This fact was utilized in the past to obtain superior filter performance by applying normalization to the filter measurement update of the quaternion. It was observed for the AEKF that when the attitude changed very slowly between measurements, normalization merely resulted in a faster convergence; however, when the attitude changed considerably between measurements, without filter tuning or normalization, the quaternion estimate diverged. However, when the

  9. Spacecraft Electrical Connector Selection and Application Processes

    Science.gov (United States)

    Iannello, Chris; Davis, Mitchell I; Kichak, Robert A.; Slenski, George

    2009-01-01

    This assessment was initiated by the NASA Engineering & Safety Center (NESC) after a number of recent "high profile" connector problems, the most visible and publicized of these being the problem with the Space Shuttle's Engine Cut-Off System cryogenic feed-thru connector. The NESC commissioned a review of NASA's connector selection and application processes for space flight applications, including how lessons learned and past problem records are fed back into the processes to avoid recurring issues. Team members were primarily from the various NASA Centers and included connector and electrical parts specialists. The commissioned study was conducted on spacecraft connector selection and application processes at NASA Centers. The team also compared the NASA spacecraft connector selection and application process to the military process, identified recent high profile connector failures, and analyzed problem report data looking for trends and common occurrences. The team characterized NASA's connector problem experience into a list of top connector issues based on anecdotal evidence of a system's impact and commonality between Centers. These top issues are as follows, in no particular rank order: electrically shorted, bent and/or recessed contact pins, contact pin/socket contamination leading to electrically open or intermittencies, connector plating corrosion or corrosion of connector components, low or inadequate contact pin retention forces, contact crimp failures, unmated connectors and mis-wiring due to workmanship errors during installation or maintenance, loose connectors due to manufacturing defects such as wavy washer and worn bayonet retention, damaged connector elastomeric seals and cryogenic connector failure. A survey was also conducted of SAE Connector AE-8C1 committee members regarding their experience relative to the NASA concerns on connectors. The most common responses in order of occurrence were contact retention, plating issues, worn-out or damaged

  10. Spacecraft vehicle design considerations and trades utilizing solar and nuclear reactor electric power systems

    Science.gov (United States)

    Bailey, Patrick G.

    1993-02-01

    The status of the reviews and the work performed to evaluate the capabilities and limitations of various nuclear power systems for space mission applications in the 5-20 kWe range. The study found that, out of nine nuclear power systems studied, three could be used to replace a 10 kWe solar array power system on a representative surveillance satellite. Each of these systems could be incorporated using a boom without major specific modifications to a baseline spacecraft design.

  11. Laser-based Relative Navigation Using GPS Measurements for Spacecraft Formation Flying

    Directory of Open Access Journals (Sweden)

    Kwangwon Lee

    2015-12-01

    Full Text Available This study presents a precise relative navigation algorithm using both laser and Global Positioning System (GPS measurements in real time. The measurement model of the navigation algorithm between two spacecraft is comprised of relative distances measured by laser instruments and single differences of GPS pseudo-range measurements in spherical coordinates. Based on the measurement model, the Extended Kalman Filter (EKF is applied to smooth the pseudo-range measurements and to obtain the relative navigation solution. While the navigation algorithm using only laser measurements might become inaccurate because of the limited accuracy of spacecraft attitude estimation when the distance between spacecraft is rather large, the proposed approach is able to provide an accurate solution even in such cases by employing the smoothed GPS pseudo-range measurements. Numerical simulations demonstrate that the errors of the proposed algorithm are reduced by more than about 12% compared to those of an algorithm using only laser measurements, as the accuracy of angular measurements is greater than 0.001° at relative distances greater than 30 km.

  12. Spacecraft with gradual acceleration of solar panels

    Science.gov (United States)

    Merhav, Tamir R. (Inventor); Festa, Michael T. (Inventor); Stetson, Jr., John B. (Inventor)

    1996-01-01

    A spacecraft (8) includes a movable appendage such as solar panels (12) operated by a stepping motor (28) driven by pulses (311). In order to reduce vibration andor attitude error, the drive pulses are generated by a clock down-counter (312) with variable count ratio. Predetermined desired clock ratios are stored in selectable memories (314a-d), and the selected ratio (R) is coupled to a comparator (330) together with the current ratio (C). An up-down counter (340) establishes the current count-down ratio by counting toward the desired ratio under the control of the comparator; thus, a step change of solar panel speed never occurs. When a direction change is commanded, a flag signal generator (350) disables the selectable memories, and enables a further store (360), which generates a count ratio representing a very slow solar panel rotational rate, so that the rotational rate always slows to a low value before direction is changed. The principles of the invention are applicable to any movable appendage.

  13. NASA Medical Response to Human Spacecraft Accidents

    Science.gov (United States)

    Patlach, Robert

    2011-01-01

    This slide presentation reviews NASA's role in the response to spacecraft accidents that involve human fatalities or injuries. Particular attention is given to the work of the Mishap Investigation Team (MIT), the first response to the accidents and the interface to the accident investigation board. The MIT does not investigate the accident, but the objective of the MIT is to gather, guard, preserve and document the evidence. The primary medical objectives of the MIT is to receive, analyze, identify, and transport human remains, provide assistance in the recovery effort, and to provide family Casualty Coordinators with latest recovery information. The MIT while it does not determine the cause of the accident, it acts as the fact gathering arm of the Mishap Investigation Board (MIB), which when it is activated may chose to continue to use the MIT as its field investigation resource. The MIT membership and the specific responsibilities and tasks of the flight surgeon is reviewed. The current law establishing the process is also reviewed.

  14. Imaging of Titan from the Cassini spacecraft.

    Science.gov (United States)

    Porco, Carolyn C; Baker, Emily; Barbara, John; Beurle, Kevin; Brahic, Andre; Burns, Joseph A; Charnoz, Sebastien; Cooper, Nick; Dawson, Douglas D; Del Genio, Anthony D; Denk, Tilmann; Dones, Luke; Dyudina, Ulyana; Evans, Michael W; Fussner, Stephanie; Giese, Bernd; Grazier, Kevin; Helfenstein, Paul; Ingersoll, Andrew P; Jacobson, Robert A; Johnson, Torrence V; McEwen, Alfred; Murray, Carl D; Neukum, Gerhard; Owen, William M; Perry, Jason; Roatsch, Thomas; Spitale, Joseph; Squyres, Steven; Thomas, Peter; Tiscareno, Matthew; Turtle, Elizabeth P; Vasavada, Ashwin R; Veverka, Joseph; Wagner, Roland; West, Robert

    2005-03-10

    Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of these issues. The images reveal intricate surface albedo features that suggest aeolian, tectonic and fluvial processes; they also show a few circular features that could be impact structures. These observations imply that substantial surface modification has occurred over Titan's history. We have not directly detected liquids on the surface to date. Convective clouds are found to be common near the south pole, and the motion of mid-latitude clouds consistently indicates eastward winds, from which we infer that the troposphere is rotating faster than the surface. A detached haze at an altitude of 500 km is 150-200 km higher than that observed by Voyager, and more tenuous haze layers are also resolved.

  15. Optimal attitude corrections for cylindrical spacecraft

    Science.gov (United States)

    Zanardi, M. C.; Santos, R. M. K.; da Silva Fernandes, S.

    2003-04-01

    A first order analytical model for optimal small amplitude attitude maneuvers of spacecraft with cylindrical symmetry in an elliptical orbits is presented. The optimization problem is formulated as a Mayer problem with the control torques provided by a power limited propulsion system. The state is defined by Serret-Andoyer's variables and the control by the components of the propulsive torques. The Pontryagin Maximum Principle is applied to the problem and the optimal torques are given explicitly in Serret-Andoyer's variables and their adjoints. For small amplitude attitude maneuvers, the optimal Hamiltonian function is linearized around a reference attitude. A complete first order analytical solution is obtained by simple quadrature and is expressed through a linear algebraic system involving the initial values of the adjoint variables. A numerical solution is obtained by taking the Euler angles formulation of the problem, solving the two-point boundary problem through the shooting method, and, then, determining the Serret-Andoyer variables through Serret-Andoyer transformation. Numerical results show that the first order solution provides a good approximation to the optimal control law and also that is possible to establish an optimal control law for the artificial satellite's attitude.

  16. Kalman Filter for Spinning Spacecraft Attitude Estimation

    Science.gov (United States)

    Markley, F. Landis; Sedlak, Joseph E.

    2008-01-01

    This paper presents a Kalman filter using a seven-component attitude state vector comprising the angular momentum components in an inertial reference frame, the angular momentum components in the body frame, and a rotation angle. The relatively slow variation of these parameters makes this parameterization advantageous for spinning spacecraft attitude estimation. The filter accounts for the constraint that the magnitude of the angular momentum vector is the same in the inertial and body frames by employing a reduced six-component error state. Four variants of the filter, defined by different choices for the reduced error state, are tested against a quaternion-based filter using simulated data for the THEMIS mission. Three of these variants choose three of the components of the error state to be the infinitesimal attitude error angles, facilitating the computation of measurement sensitivity matrices and causing the usual 3x3 attitude covariance matrix to be a submatrix of the 6x6 covariance of the error state. These variants differ in their choice for the other three components of the error state. The variant employing the infinitesimal attitude error angles and the angular momentum components in an inertial reference frame as the error state shows the best combination of robustness and efficiency in the simulations. Attitude estimation results using THEMIS flight data are also presented.

  17. An AFDX Network for Spacecraft Data Handling

    Science.gov (United States)

    Deredempt, Marie-Helene; Kollias, Vangelis; Sun, Zhili; Canamares, Ernest; Ricco, Philippe

    2014-08-01

    In aeronautical domain, ARINC-664 Part 7 specification (AFDX) [4] provides the enabling technology for interfacing equipment in Integrated Modular Avionics (IMA) architectures. The complementary part of AFDX for a complete interoperability - Time and Space Partitioning (ARINC 653) concepts [1]- was already studied as part of space domain ESA roadmap (i.e. IMA4Space project)Standardized IMA based architecture is already considered in aeronautical domain as more flexible, reliable and secure. Integration and validation become simple, using a common set of tools and data base and could be done by part on different means with the same definition (hardware and software test benches, flight control or alarm test benches, simulator and flight test installation).In some area, requirements in terms of data processing are quite similar in space domain and the concept could be applicable to take benefit of the technology itself and of the panel of hardware and software solutions and tools available on the market. The Mission project (Methodology and assessment for the applicability of ARINC-664 (AFDX) in Satellite/Spacecraft on-board communicatION networks), as an FP7 initiative for bringing terrestrial SME research into the space domain started to evaluate the applicability of the standard in space domain.

  18. Humidity Testing for Human Rated Spacecraft

    Science.gov (United States)

    Johnson, Gary B.

    2009-01-01

    Determination that equipment can operate in and survive exposure to the humidity environments unique to human rated spacecraft presents widely varying challenges. Equipment may need to operate in habitable volumes where the atmosphere contains perspiration, exhalation, and residual moisture. Equipment located outside the pressurized volumes may be exposed to repetitive diurnal cycles that may result in moisture absorption and/or condensation. Equipment may be thermally affected by conduction to coldplate or structure, by forced or ambient air convection (hot/cold or wet/dry), or by radiation to space through windows or hatches. The equipment s on/off state also contributes to the equipment s susceptibility to humidity. Like-equipment is sometimes used in more than one location and under varying operational modes. Due to these challenges, developing a test scenario that bounds all physical, environmental and operational modes for both pressurized and unpressurized volumes requires an integrated assessment to determine the "worst-case combined conditions." Such an assessment was performed for the Constellation program, considering all of the aforementioned variables; and a test profile was developed based on approximately 300 variable combinations. The test profile has been vetted by several subject matter experts and partially validated by testing. Final testing to determine the efficacy of the test profile on actual space hardware is in the planning stages. When validation is completed, the test profile will be formally incorporated into NASA document CxP 30036, "Constellation Environmental Qualification and Acceptance Testing Requirements (CEQATR)."

  19. Characterization of long noncoding RNA and messenger RNA signatures in melanoma tumorigenesis and metastasis.

    Science.gov (United States)

    Wang, Siqi; Fan, Wenliang; Wan, Bing; Tu, Mengqi; Jin, Feng; Liu, Fang; Xu, Haibo; Han, Ping

    2017-01-01

    The incidence of melanoma, the most aggressive and life-threatening form of skin cancer, has significantly risen over recent decades. Therefore, it is essential to identify the mechanisms that underlie melanoma tumorigenesis and metastasis and to explore novel and effective melanoma treatment strategies. Accumulating evidence s uggests that aberrantly expressed long noncoding RNAs (lncRNAs) have vital functions in multiple cancers. However, lncRNA functions in melanoma tumorigenesis and metastasis remain unclear. In this study, we investigated lncRNA and messenger RNA (mRNA) expression profiles in primary melanomas, metastatic melanomas and normal skin samples from the Gene Expression Omnibus database. We used GSE15605 as the training set (n = 74) and GSE7553 as the validation set (n = 58). In three comparisons (primary melanoma versus normal skin, metastatic melanoma versus normal skin, and metastatic melanoma versus primary melanoma), 178, 295 and 48 lncRNAs and 847, 1758, and 295 mRNAs were aberrantly expressed, respectively. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses to examine the differentially expressed mRNAs, and potential core lncRNAs were predicted by lncRNA-mRNA co-expression networks. Based on our results, 15 lncRNAs and 144 mRNAs were significantly associated with melanoma tumorigenesis and metastasis. A subsequent analysis suggested a critical role for a five-lncRNA signature during melanoma tumorigenesis and metastasis. Low expression of U47924.27 was significantly associated with decreased survival of patients with melanoma. To the best of our knowledge, this study is the first to explore the expression patterns of lncRNAs and mRNAs during melanoma tumorigenesis and metastasis by re-annotating microarray data from the Gene Expression Omnibus (GEO) microarray dataset. These findings reveal potential roles for lncRNAs during melanoma tumorigenesis and metastasis and provide a rich candidate reservoir for

  20. Opioid Tolerance and Physical Dependence: Role of Spinal Neuropeptides, Excitatory Amino Acids and Their Messengers

    Directory of Open Access Journals (Sweden)

    Khem Jhamandas

    2000-01-01

    Full Text Available Chronic opioid treatment results in the development of tolerance and physical dependence. The mechanisms underlying opioid tolerance and/or physical dependence are unclear. Recent studies suggest that opioid receptor or nociceptive, neural network-based adaptations contribute to this phenomenon. At the spinal level, the genesis of tolerance and physical dependence is associated with increased excitatory amino acid activity expressed through N-methyl-D-aspartate receptors in the dorsal horn. However, recent evidence also implicates spinal neuropeptide transmitters such as calcitonin gene-related peptide (CGRP and  substance P in the development of opioid tolerance. Long term spinal morphine treatment increases CGRP-like immunostaining in the dorsal horn, and coadministration of morphine with CGRP8-37, a competitive CGRP1 receptor antagonist, prevents this response as well as loss of the analgesic potency. CGRP8-37, like N-methyl-D-aspartate receptor antagonists, has the potential to restore morphine potency in experimental animals who are already tolerant to the opioid agonist. Recent evidence suggests that the effects of excitatory amino acid and neuropeptide receptor activity may be expressed through the generation of messengers such as nitric oxide and prostanoids. Agents that inhibit the synthesis of nitric oxide and prostanoids have the potential to inhibit and reverse spinal opioid tolerance, suggesting that this phenomenon may be expressed through the activity of these mediators. Nociceptive transmission in the dorsal horn of the spinal cord also involves activity of a number of other mediators including morphine modulatory neuropeptides, neuropeptide FF  and neuropeptide SF. The role of these mediators and their relationship with other factors implicated in tolerance remain to be determined.

  1. School-based participatory health education for malaria control in Ghana: engaging children as health messengers

    Directory of Open Access Journals (Sweden)

    Mizoue Tetsuya

    2010-04-01

    Full Text Available Abstract Background School children have been increasingly recognized as health messengers for malaria control. However, little evidence is available. The objective of this study was to determine the impact of school-based malaria education intervention on school children and community adults. Methods This study was conducted in the Dangme-East district of the Greater Accra Region, Ghana, between 2007 and 2008. Trained schoolteachers designed participatory health education activities and led school children to disseminate messages related to malaria control to their communities. Three schools and their respective communities were chosen for the study and assigned to an intervention group (one school and a control group (two schools. Questionnaire-based interviews and parasitological surveys were conducted before and after the intervention, with the intervention group (105 children, 250 community adults and the control group (81 children, 133 community adults. Chi-square and Fisher's Exact tests were used to analyse differences in knowledge, practices, and parasite prevalence between pre- and post-intervention. Results After the intervention, the misperception that malaria has multiple causes was significantly improved, both among children and community adults. Moreover, the community adults who treated a bed net with insecticide in the past six months, increased from 21.5% to 50.0% (p p = 0.003. These positive changes were observed only in the intervention group. Conclusions This study suggests that the participatory health education intervention contributed to the decreased malaria prevalence among children. It had a positive impact not only on school children, but also on community adults, through the improvement of knowledge and practices. This strategy can be applied as a complementary approach to existing malaria control strategies in West African countries where school health management systems have been strengthened.

  2. School-based participatory health education for malaria control in Ghana: engaging children as health messengers.

    Science.gov (United States)

    Ayi, Irene; Nonaka, Daisuke; Adjovu, Josiah K; Hanafusa, Shigeki; Jimba, Masamine; Bosompem, Kwabena M; Mizoue, Tetsuya; Takeuchi, Tsutomu; Boakye, Daniel A; Kobayashi, Jun

    2010-04-18

    School children have been increasingly recognized as health messengers for malaria control. However, little evidence is available. The objective of this study was to determine the impact of school-based malaria education intervention on school children and community adults. This study was conducted in the Dangme-East district of the Greater Accra Region, Ghana, between 2007 and 2008. Trained schoolteachers designed participatory health education activities and led school children to disseminate messages related to malaria control to their communities. Three schools and their respective communities were chosen for the study and assigned to an intervention group (one school) and a control group (two schools). Questionnaire-based interviews and parasitological surveys were conducted before and after the intervention, with the intervention group (105 children, 250 community adults) and the control group (81 children, 133 community adults). Chi-square and Fisher's Exact tests were used to analyse differences in knowledge, practices, and parasite prevalence between pre- and post-intervention. After the intervention, the misperception that malaria has multiple causes was significantly improved, both among children and community adults. Moreover, the community adults who treated a bed net with insecticide in the past six months, increased from 21.5% to 50.0% (p < 0.001). Parasite prevalence in school children decreased from 30.9% to 10.3% (p = 0.003). These positive changes were observed only in the intervention group. This study suggests that the participatory health education intervention contributed to the decreased malaria prevalence among children. It had a positive impact not only on school children, but also on community adults, through the improvement of knowledge and practices. This strategy can be applied as a complementary approach to existing malaria control strategies in West African countries where school health management systems have been strengthened.

  3. The ribosome uses two active mechanisms to unwind messenger RNA during translation.

    Science.gov (United States)

    Qu, Xiaohui; Wen, Jin-Der; Lancaster, Laura; Noller, Harry F; Bustamante, Carlos; Tinoco, Ignacio

    2011-07-06

    The ribosome translates the genetic information encoded in messenger RNA into protein. Folded structures in the coding region of an mRNA represent a kinetic barrier that lowers the peptide elongation rate, as the ribosome must disrupt structures it encounters in the mRNA at its entry site to allow translocation to the next codon. Such structures are exploited by the cell to create diverse strategies for translation regulation, such as programmed frameshifting, the modulation of protein expression levels, ribosome localization and co-translational protein folding. Although strand separation activity is inherent to the ribosome, requiring no exogenous helicases, its mechanism is still unknown. Here, using a single-molecule optical tweezers assay on mRNA hairpins, we find that the translation rate of identical codons at the decoding centre is greatly influenced by the GC content of folded structures at the mRNA entry site. Furthermore, force applied to the ends of the hairpin to favour its unfolding significantly speeds translation. Quantitative analysis of the force dependence of its helicase activity reveals that the ribosome, unlike previously studied helicases, uses two distinct active mechanisms to unwind mRNA structure: it destabilizes the helical junction at the mRNA entry site by biasing its thermal fluctuations towards the open state, increasing the probability of the ribosome translocating unhindered; and it mechanically pulls apart the mRNA single strands of the closed junction during the conformational changes that accompany ribosome translocation. The second of these mechanisms ensures a minimal basal rate of translation in the cell; specialized, mechanically stable structures are required to stall the ribosome temporarily. Our results establish a quantitative mechanical basis for understanding the mechanism of regulation of the elongation rate of translation by structured mRNAs. ©2011 Macmillan Publishers Limited. All rights reserved

  4. Deep Infiltrating Endometriosis and Endometrial Adenocarcinoma Express High Levels of Myostatin and Its Receptors Messenger RNAs.

    Science.gov (United States)

    Carrarelli, Patrizia; Funghi, Lucia; Ciarmela, Pasquapina; Centini, Gabriele; Reis, Fernando M; Dela Cruz, Cynthia; Mattei, Alberto; Vannuccini, Silvia; Petraglia, Felice

    2017-12-01

    Myostatin is a growth factor member of the transforming growth factor β superfamily, which is known to play major roles in cell proliferation and differentiation. The present study investigated the messenger RNA (mRNA) expression of myostatin and myostatin receptors (activin receptor-like kinase 4 [ALK4], transforming growth factor (TGF)-β type I receptor kinase [ALK5] and activin receptor type IIB [ActRIIB]) in endometrium of healthy women during menstrual cycle as well as in benign (endometriosis, polyps) and malignant (endometrial adenocarcinoma) conditions. Endometrial specimens were collected by hysteroscopy, whereas endometriotic lesions were collected by laparoscopy, and adenocarcinomas were sampled after hysterectomy. Total RNA was extracted from tissue homogenates, and gene expression was assessed by quantitative real-time polymerase chain reaction. Myostatin and myostatin receptors mRNAs were expressed by healthy endometrium throughout the menstrual cycle, with no differences between the proliferative and secretory phase. The highest myostatin mRNA expression was found in patients with deep infiltrating endometriosis (DIE) and in endometrial carcinoma; expression was also found in ovarian endometrioma (OMA ) and endometrial polyps. Myostatin receptors mRNA expression was higher in DIE and adenocarcinomas compared to control endometrium. The expression of ALK5 and ActRIIB in OMA was higher than in controls, whereas polyps had an increased expression of ALK5 mRNA. In conclusion, the present data showed for the first time the expression of myostatin in healthy endometrium and a higher expression in endometriosis and endometrial cancer, suggesting myostatin involvement in human endometrial physiology and related pathologies.

  5. Antigen-presenting cells transfected with Hsp65 messenger RNA fail to treat experimental tuberculosis

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, C.D.; Trombone, A.P.F.; Lorenzi, J.C.C.; Almeida, L.P.; Gembre, A.F.; Padilha, E. [Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Ramos, S.G. [Departamento de Patologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Silva, C.L.; Coelho-Castelo, A.A.M. [Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

    2012-09-21

    In the last several years, the use of dendritic cells has been studied as a therapeutic strategy against tumors. Dendritic cells can be pulsed with peptides or full-length protein, or they can be transfected with DNA or RNA. However, comparative studies suggest that transfecting dendritic cells with messenger RNA (mRNA) is superior to other antigen-loading techniques in generating immunocompetent dendritic cells. In the present study, we evaluated a new therapeutic strategy to fight tuberculosis using dendritic cells and macrophages transfected with Hsp65 mRNA. First, we demonstrated that antigen-presenting cells transfected with Hsp65 mRNA exhibit a higher level of expression of co-stimulatory molecules, suggesting that Hsp65 mRNA has immunostimulatory properties. We also demonstrated that spleen cells obtained from animals immunized with mock and Hsp65 mRNA-transfected dendritic cells were able to generate a mixed Th1/Th2 response with production not only of IFN-γ but also of IL-5 and IL-10. In contrast, cells recovered from mice immunized with Hsp65 mRNA-transfected macrophages were able to produce only IL-5. When mice were infected with Mycobacterium tuberculosis and treated with antigen-presenting cells transfected with Hsp65 mRNA (therapeutic immunization), we did not detect any decrease in the lung bacterial load or any preservation of the lung parenchyma, indicating the inability of transfected cells to confer curative effects against tuberculosis. In spite of the lack of therapeutic efficacy, this study reports for the first time the use of antigen-presenting cells transfected with mRNA in experimental tuberculosis.

  6. Medical Information Exchange: Pattern of Global Mobile Messenger Usage among Otolaryngologists.

    Science.gov (United States)

    Siegal, Gil; Dagan, Elad; Wolf, Michael; Duvdevani, Shay; Alon, Eran E

    2016-11-01

    Information technology has revolutionized health care. However, the development of dedicated mobile health software has been lagging, leading to the use of general mobile applications to fill in the void. The use of such applications has several legal, ethical, and regulatory implications. We examined the experience and practices governing the usage of a global mobile messenger application (WhatsApp) for mobile health purposes in a national cohort of practicing otolaryngologists in Israel, a known early adaptor information technology society. Cross-sectional data were collected from practicing otolaryngologists and otolaryngology residents via self-administered questionnaire. The questionnaire was composed of a demographic section, a section surveying the practices of mobile application use, mobile health application use, and knowledge regarding institutional policies governing the transmission of medical data. The sample included 22 otolaryngology residents and 47 practicing otolaryngologists. Of the physicians, 83% worked in academic centers, and 88% and 40% of the physicians who worked in a hospital setting or a community clinic used WhatsApp for medical use, respectively. Working with residents increased the medical usage of WhatsApp from 50% to 91% (P = .006). Finally, 72% were unfamiliar with any institutional policy regarding the transfer of medical information by personal smartphones. Mobile health is becoming an integral part of modern medical systems, improving accessibility, efficiency, and possibly quality of medical care. The need to incorporate personal mobile devices in the overall information technology standards, guidelines, and regulation is becoming more acute. Nonetheless, practices must be properly instituted to prevent unwanted consequences. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

  7. Integrated controls-structures design methodology development for a class of flexible spacecraft

    Science.gov (United States)

    Maghami, P. G.; Joshi, S. M.; Walz, J. E.; Armstrong, E. S.

    1990-01-01

    Future utilization of space will require large space structures in low-Earth and geostationary orbits. Example missions include: Earth observation systems, personal communication systems, space science missions, space processing facilities, etc., requiring large antennas, platforms, and solar arrays. The dimensions of such structures will range from a few meters to possibly hundreds of meters. For reducing the cost of construction, launching, and operating (e.g., energy required for reboosting and control), it will be necessary to make the structure as light as possible. However, reducing structural mass tends to increase the flexibility which would make it more difficult to control with the specified precision in attitude and shape. Therefore, there is a need to develop a methodology for designing space structures which are optimal with respect to both structural design and control design. In the current spacecraft design practice, it is customary to first perform the structural design and then the controller design. However, the structural design and the control design problems are substantially coupled and must be considered concurrently in order to obtain a truly optimal spacecraft design. For example, let C denote the set of the 'control' design variables (e.g., controller gains), and L the set of the 'structural' design variables (e.g., member sizes). If a structural member thickness is changed, the dynamics would change which would then change the control law and the actuator mass. That would, in turn, change the structural model. Thus, the sets C and L depend on each other. Future space structures can be roughly divided into four mission classes. Class 1 missions include flexible spacecraft with no articulated appendages which require fine attitude pointing and vibration suppression (e.g., large space antennas). Class 2 missions consist of flexible spacecraft with articulated multiple payloads, where the requirement is to fine-point the spacecraft and each

  8. Analysis of Opportunities for Intercalibration Between Two Spacecraft. Chapter 1

    Science.gov (United States)

    Roithmayr, Carlos M.; Speth, Paul W.

    2012-01-01

    There is currently a strong interest in obtaining highly accurate measurements of solar radiation reflected by Earth. For example, the Traceable Radiometry Underpinning Terrestrial- and Helio- Studies (TRUTHS) satellite mission has been under consideration in Europe for several years, and planning is now under way for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) spacecraft in the United States. Such spacecraft will provide measurements whose high accuracy is traceable to SI standards; these measurements will be useful as a reference for calibrating similar instruments on board other spacecraft. Hence, analysis of opportunities for intercalibration between two spacecraft plays an important role in the planning of future missions. In order for intercalibration to take place, the measurements obtained from two spacecraft must have similar viewing geometry and be taken within a few minutes of one another. Viewing geometry is characterized in terms of viewing zenith angle, solar zenith angle, and relative azimuth angle. Opportunities for intercalibration are greater in number and longer in duration if the sensor with high accuracy can be aimed at points on the surface of the Earth other than the nadir or sub-satellite point. Analysis of intercalibration over long periods is rendered tractable by making several simplifying assumptions regarding orbital motions of the two spacecraft about Earth, as well as Earth s orbit about the Sun. The shape of the Earth is also considered. A geometric construction called a tent is introduced to facilitate analysis. It is helpful to think of an intercalibration opportunity as the passage of one spacecraft through a tent that has a fixed shape and moves with the spacecraft whose measurements are to be calibrated. Selection of points on Earth s surface as targets for measurement is discussed, as is aiming the boresight of a steerable instrument. Analysis results for a pair of spacecraft in typical low Earth orbits

  9. Fullerenes in an impact crater on the LDEF spacecraft

    Science.gov (United States)

    Radicati di Brozolo, F.; Bunch, T. E.; Fleming, R. H.; Macklin, J.

    1994-01-01

    The fullerenes C60 and C70 have been found to occur naturally on Earth and have also been invoked to explain features in the absorption spectra of interstellar clouds. But no definitive spectroscopic evidence exists for fullerenes in space and attempts to find fullerenes in carbonaceous chondrites have been unsuccessful. Here we report the observation of fullerenes associated with carbonaceous impact residue in a crater on the Long Duration Exposure Facility (LDEF) spacecraft. Laser ionization mass spectrometry and Raman spectroscopy indicate the presence of fullerenes in the crater and in adjacent ejecta. Man-made fullerenes survive experimental hypervelocity (approximately 6.1 km s-1) impacts into aluminium targets, suggesting that space fullerenes contained in a carbonaceous micrometeorite could have survived the LDEF impact at velocities towards the lower end of the natural particle encounter range (fullerenes were unlikely to have formed as instrumental artefacts, nor are they present as contaminants. Although we cannot specify the origin of the fullerenes with certainty, the most plausible source is the chondritic impactor. If, alternatively, the impact produced the fullerenes in situ on LDEF, then this suggests a viable mechanism for fullerene production in space.

  10. Western hemisphere of the Moon taken by Galileo spacecraft

    Science.gov (United States)

    1990-01-01

    Galileo spacecraft image of the Moon recorded at 9:35 am Pacific Standard Time (PST), 12-09-90, after completing its first Earth Gravity Assist. Western hemisphere of the Moon was taken through a green filter at a range of about 350,000 miles. In the center is Orientale Basin, 600 miles in diameter, formed about 3.8 billion years ago by the impact of an asteroid-size body. Orientale's dark center is a small mare. To the right is the lunar near side with the great, dark Oceanus Procellarum above the small, circular, dark Mare Humorum below. Maria are broad plains formed mostly over 3 billion years ago as vast basaltic lava flows. To the left is the lunar far side with fewer maria, but, at lower left South-Pole-Aitken basin, about 1200 miles in diameter, which resembles Orientale but is much older and more weathered and battered by cratering. The intervening cratered highlands of both sides, as well as the maria, are dotted with bright young craters. This image was 'reprojected' so as to

  11. Spin-Stabilized Spacecrafts: Analytical Attitude Propagation Using Magnetic Torques

    Directory of Open Access Journals (Sweden)

    Roberta Veloso Garcia

    2009-01-01

    Full Text Available An analytical approach for spin-stabilized satellites attitude propagation is presented, considering the influence of the residual magnetic torque and eddy currents torque. It is assumed two approaches to examine the influence of external torques acting during the motion of the satellite, with the Earth's magnetic field described by the quadripole model. In the first approach is included only the residual magnetic torque in the motion equations, with the satellites in circular or elliptical orbit. In the second approach only the eddy currents torque is analyzed, with the satellite in circular orbit. The inclusion of these torques on the dynamic equations of spin stabilized satellites yields the conditions to derive an analytical solution. The solutions show that residual torque does not affect the spin velocity magnitude, contributing only for the precession and the drift of the spacecraft's spin axis and the eddy currents torque causes an exponential decay of the angular velocity magnitude. Numerical simulations performed with data of the Brazilian Satellites (SCD1 and SCD2 show the period that analytical solution can be used to the attitude propagation, within the dispersion range of the attitude determination system performance of Satellite Control Center of Brazil National Research Institute.

  12. Application of DSN spacecraft tracking technology to experimental gravitation

    Science.gov (United States)

    Anderson, J. D.; Estabrook, F. B.

    1978-01-01

    Spacecraft tracking technology of the Deep Space Net (DSN) has been used in the past to measure the general-relativistic increase in round-trip group delay between earth and a spacecraft. As the DSN technology continues to improve, other gravitational experiments will become possible. Two possibilities are discussed in this paper. The first concerns the application of solar-system dynamics to the testing of general relativity. The second involves the detection of VLF gravitational radiation (0.1 to 0.0001 Hz) by means of Doppler tracking of spacecraft.

  13. Fifty-one years of Los Alamos Spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-09-04

    From 1963 to 2014, the Los Alamos National Laboratory was involved in at least 233 spacecraft. There are probably only one or two institutions in the world that have been involved in so many spacecraft. Los Alamos space exploration started with the Vela satellites for nuclear test detection, but soon expanded to ionospheric research (mostly barium releases), radioisotope thermoelectric generators, solar physics, solar wind, magnetospheres, astrophysics, national security, planetary physics, earth resources, radio propagation in the ionosphere, and cubesats. Here, we present a list of the spacecraft, their purpose, and their launch dates for use during RocketFest

  14. Cooper-Harper Experience Report for Spacecraft Handling Qualities Applications

    Science.gov (United States)

    Bailey, Randall E.; Jackson, E. Bruce; Bilimoria, Karl D.; Mueller, Eric R.; Frost, Chad R.; Alderete, Thomas S.

    2009-01-01

    A synopsis of experience from the fixed-wing and rotary-wing aircraft communities in handling qualities development and the use of the Cooper-Harper pilot rating scale is presented as background for spacecraft handling qualities research, development, test, and evaluation (RDT&E). In addition, handling qualities experiences and lessons-learned from previous United States (US) spacecraft developments are reviewed. This report is intended to provide a central location for references, best practices, and lessons-learned to guide current and future spacecraft handling qualities RDT&E.

  15. Electronics speckle interferometry applications for NDE of spacecraft structural components

    Science.gov (United States)

    Rao, M. V.; Samuel, R.; Ananthan, A.; Dasgupta, S.; Nair, P. S.

    2008-09-01

    The spacecraft components viz., central cylinder, deck plates, solar panel substrates, antenna reflectors are made of aluminium/composite honeycomb sandwich construction. Detection of these defects spacecraft structural components is important to assess the integrity of the spacecraft structure. Electronic Speckle Interferometry (ESI) techniques identify the defects as anomalous regions in the interferometric fringe patterns of the specklegram while the component is suitably stressed to give rise to differential displacement/strain around the defective region. Calibration studies, different phase shifting methods associated with ESI and the development of a prototype Twin Head ESSI System (THESSIS) and its use for the NDE of a typical satellite structural component are presented.

  16. Trajectory Design for the Phobos and Deimos & Mars Environment Spacecraft

    Science.gov (United States)

    Genova, Anthony L.; Korsmeyer, David J.; Loucks, Michel E.; Yang, Fan Yang; Lee, Pascal

    2016-01-01

    The presented trajectory design and analysis was performed for the Phobos and Deimos & Mars Environment (PADME) mission concept as part of a NASA proposal submission managed by NASA Ames Research Center in the 2014-2015 timeframe. The PADME spacecraft would be a derivative of the successfully flown Lunar Atmosphere & Dust Environment Explorer (LADEE) spacecraft. While LADEE was designed to enter low-lunar orbit, the PADME spacecraft would instead enter an elliptical Mars orbit of 2-week period. This Mars orbit would pass by Phobos near periapsis on successive orbits and then raise periapsis to yield close approaches of Deimos every orbit thereafter.

  17. GIOTTO ION MASS SPECTROMETER HIGH ENERGY RANGE DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — A wide range of ion species and velocity distributions are expected to be found as the Giotto spacecraft traverses the coma of Halley's Comet. The outer coma is...

  18. Scaled CMOS Reliability and Considerations for Spacecraft Systems: Bottom-Up and Top-Down Perspective

    Science.gov (United States)

    White, Mark

    2012-01-01

    New space missions will increasingly rely on more advanced technologies because of system requirements for higher performance, particularly in instruments and high-speed processing. Component-level reliability challenges with scaled CMOS in spacecraft systems from a bottom-up perspective have been presented. Fundamental Front-end and Back-end processing reliability issues with more aggressively scaled parts have been discussed. Effective thermal management from system-level to the componentlevel (top-down) is a key element in overall design of reliable systems. Thermal management in space systems must consider a wide range of issues, including thermal loading of many different components, and frequent temperature cycling of some systems. Both perspectives (top-down and bottom-up) play a large role in robust, reliable spacecraft system design.

  19. Revamping Spacecraft Operational Intelligence with Splunk

    Science.gov (United States)

    Hwang, Victor

    2012-01-01

    So what is Splunk? Instead of giving the technical details, which you can find online, I'll tell you what it did for me. Splunk slapped everything into one place, with one uniform format, and gave me the ability to forget about all these annoying details of where it is, how to parse it, and all that. Instead, I only need to interact with Splunk to find the data I need. This sounds simple and obvious, but it's surprising what you can do once you all of your data is indexed in one place. By having your data organized, querying becomes much easier. Let's say that I want to search telemetry for a sensor_name gtemp_1 h and to return all data that is at most five minutes old. And because Splunk can hook into a real ]time stream, this data will always be up-to-date. Extending the previous example, I can now aggregate all types of data into one view based in time. In this picture, I've got transaction logs, telemetry, and downlinked files all in one page, organized by time. Even though the raw data looks completely than this, I've defined interfaces that transform it into this uniform format. This gives me a more complete picture for the question what was the spacecraft doing at this particular time? And because querying data is simple, I can start with a big block of data and whiddle it down to what I need, rather than hunting around for the individual pieces of data that I need. When we have all the data we need, we can begin widdling down the data with Splunk's Unix-like search syntax. These three examples highlights my trial-and-error attempts to find large temperature changes. I begin by showing the first 5 temperatures, only to find that they're sorted chronologically, rather than from highest temperatures to lowest temperatures. The next line shows sorting temperatures by their values, but I find that that fs not really what I want either. I want to know the delta temperatures between readings. Looking through Splunk's user manual, I find the delta function, which

  20. Spacecraft Environment May Reduce Resistance To Infection

    Science.gov (United States)

    Pierson, Duane L.; Ott, C. Mark; Castro, V. A.; Leal, Melanie; Mehta, Satish K.

    2006-01-01

    Living and working in a spacecraft exposes the crew to a unique environment. This environment includes microgravity, increased radiation, chemical and biological contamination, and a variety of stressors. Disturbances in this balance are often manifested by diminished immunity in astronauts/cosmonauts. Reactivation of Epstein- Barr virus (EBV), cytomegalovirus (CMV), and varicella-zoster virus (VZV) has been used as an indicator of immune status. Reactivation of EBV and VZV were detected and quantified in saliva. CMV was measured in urine. The DNA was extracted using a Qiagen Inc. kit and viral DNA was detected by real time polymerase chain reaction (PCR) based assay with Taqman 7700 (PE Biosystems). Patterns of Epstein-Barr virus (EBV) reactivation in 32 astronauts and 18 healthy age-matched control subjects were characterized by quantifying EBV shedding. Saliva samples were collected before, during, and after 10 space shuttle missions of 5 to 14 d duration. Of 1398 saliva specimens from 32 astronauts, 314 (23%) were positive for EBV DNA. Examination by flight phase showed that 29% of the saliva specimens collected from 28 astronauts before flight were positive for EBV DNA, as were 16% of those collected from 25 astronauts during flight and 16% of those collected after flight from 23 astronauts. The mean number of EBV copies/mL from samples taken during the flights was 417, ten-fold greater (p < 0.05) than the copies from the preflight (40) and post flight (44) phases. In contrast, the control subjects shed EBV DNA with a frequency of 3.7% and mean EBV copies of 40 per mL of saliva. Ten days before flight and on landing day, titers of antibody to EBV viral capsid antigen were significantly (p < 0.05) greater than baseline levels. Increases in the number of viral copies and in the amount of EBV-specific antibody were consistent with EBV reactivation before, during, and after space flight. Similarly, CMV and VZV reactivation increased in response to space flight

  1. A Data Abstraction Architecture for Spacecraft Autonomy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft generate huge amounts of data. A significant challenge for both human operators and autonomous control systems is ensuring that the right data (and...

  2. Modeling Vacuum Arcs On Spacecraft Solar Panel Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft charging and subsequent vacuum arcing poses a significant threat to satellites in LEO and GEO plasma conditions. Localized arc discharges can cause a...

  3. High-Performance Contaminant Monitor for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Vision for Space Exploration demands increasing reliance on real-time trace gas monitors onboard spacecraft. Present grab samples and badges will be inadequate...

  4. Autonomous Supervisory Engine for Multi-Spacecraft Formation Flying Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of this project is to develop an onboard, autonomous Multi-spacecraft Supervisory Engine (MSE) for formation-flying guidance, navigation and control...

  5. Diagnosing Faults in Electrical Power Systems of Spacecraft and Aircraft

    Data.gov (United States)

    National Aeronautics and Space Administration — Electrical power systems play a critical role in spacecraft and aircraft, and they exhibit a rich variety of failure modes. This paper discusses electrical power...

  6. High Throughput Hall Thruster for Small Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek Co. Inc. proposes to develop a high throughput, nominal 100 W Hall Effect Thruster (HET). This HET will be sized for small spacecraft (< 180 kg), including...

  7. Conceptual definition of Automated Power Systems Management. [for planetary spacecraft

    Science.gov (United States)

    Imamura, M. S.; Skelly, L.; Weiner, H.

    1977-01-01

    Automated Power Systems Management (APSM) is defined as the capability of a spacecraft power system to automatically perform monitoring, computational, command, and control functions without ground intervention. Power systems for future planetary spacecraft must have this capability because they must perform up to 10 years, and accommodate real-time changes in mission execution autonomously. Specific APSM functions include fault detection, isolation, and correction; system performance and load profile prediction; power system optimization; system checkout; and data storage and transmission control. This paper describes the basic method of implementing these specific functions. The APSM hardware includes a central power system computer and a processor dedicated to each major power system subassembly along with digital interface circuitry. The major payoffs anticipated are in enhancement of spacecraft reliability and life and reduction of overall spacecraft program cost.

  8. Passive Devices for Advanced Fluid Management aboard Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Acute challenges are faced by the designers of fluid systems for spacecraft because of the persistently unfamiliar and unforgiving low-g environment. For example,...

  9. Advanced Portable Fine Water Mist Fire Extinguisher for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fine water mist (FWM) is a promising replacement technology for fire suppression on the next generation of manned spacecraft. It offers advantages in performance,...

  10. Charge Dissipating Transparent Conformal Coatings for Spacecraft Electronics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The space environment poses significant challenges to spacecraft electronics in the form of electrostatic discharge (ESD) as a result of exposure to highly charged...

  11. Fractionated spacecraft : The new sprout in distributed space systems

    NARCIS (Netherlands)

    Guo, J.; Maessen, D.C.; Gill, E.K.A.

    2009-01-01

    This paper provides a survey of current state-of-the-art technologies of fractionated spacecraft, a new architecture for distributed space systems. The survey covers six aspects: architecture, networking, wireless communication, wireless power transfer, distributed computing, and planned missions

  12. A new environment for multiple spacecraft power subsystem mission operations

    Science.gov (United States)

    Bahrami, K. A.

    1990-01-01

    The engineering analysis subsystem environment (EASE) is being developed to enable fewer controllers to monitor and control power and other spacecraft engineering subsystems. The EASE prototype has been developed to support simultaneous real-time monitoring of several spacecraft engineering subsystems. It is being designed to assist with offline analysis of telemetry data to determine trends, and to help formulate uplink commands to the spacecraft. An early version of the EASE prototype has been installed in the JPL Space Flight Operations Facility for online testing. The EASE prototype is installed in the Galileo Mission Support Area. The underlying concept, development, and testing of the EASE prototype and how it will aid in the ground operations of spacecraft power subsystems are discussed.

  13. 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.

  14. Novel Metal Organic Framework Synthesis for Spacecraft Oxygen Capture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek and University of Utah propose to develop novel metal organic framework (MOF) material to efficiently capture oxygen in spacecraft cabin environment. The...

  15. Dynamics, Distributed Control and Autonomous Cluster Operations of Fractionated Spacecraft

    NARCIS (Netherlands)

    Chu, J.

    2015-01-01

    Fractionated spacecraft deploy satellites' functionalities, such as computation, communication, data storage, payload operations and even power generation, onboard several modules that share those functionalities through a wireless network. With the advent of such an innovative space architecture,

  16. Wireless Data and Power Transfer on Small Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Achieving low-cost space missions implies lowering all phases of mission development, including spacecraft design, assembly, integration and test. The concept of the...

  17. Foil Gas Bearing Supported Quiet Fan for Spacecraft Ventilation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Developing a quiet fan for Environmental Control and Life Support systems to enhance the livable environment within the spacecraft has been a challenge. A Foil Gas...

  18. Spacecraft Water Regeneration by Catalytic Wet Air Oxidation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is to develop advanced catalysts for a volatile removal assembly used to purify spacecraft water. The innovation of the proposed...

  19. Internal Mass Motion for Spacecraft Dynamics and Control

    National Research Council Canada - National Science Library

    Hall, Christopher D

    2008-01-01

    We present a detailed description of the application of a noncanonical Hamiltonian formulation to the modeling, analysis, and simulation of the dynamics of gyrostat spacecraft with internal mass motion...

  20. Aerogel Insulation for the Thermal Protection of Venus Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — One of NASA's primary goals for the next decade is the design, development and launch of a spacecraft aimed at the in-situ exploration of the deep atmosphere and...

  1. Effects of Knowledge Reuse on the Spacecraft Development Process

    Science.gov (United States)

    Dutton, Esther S.

    1997-01-01

    The experimental objective was to assess the impact of knowledge reuse on spacecraft development time. A Secondary objective was to produce a comprehensive, flexible model other DNP teams could use to test their methodologies.

  2. Distributed Control Architectures for Precision Spacecraft Formations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LaunchPoint Technologies, Inc. (LaunchPoint) proposes to develop synthesis methods and design architectures for distributed control systems in precision spacecraft...

  3. Triple3 Redundant Spacecraft Subsystems (T3RSS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Redefine Technologies, along with researchers at the University of Colorado, will use three redundancy methods to decrease the susceptibility of a spacecraft, on a...

  4. Spacecraft Thermal Control System Not Requiring Power Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The thermal management of spacecraft would be enhanced by dynamic control over surface emissivity in the mid-infrared. In this SBIR program, Triton Systems proposes...

  5. A small spacecraft for multipoint measurement of ionospheric plasma

    Science.gov (United States)

    Roberts, T. M.; Lynch, K. A.; Clayton, R. E.; Weiss, J.; Hampton, D. L.

    2017-07-01

    Measurement of ionospheric plasma is often performed by a single in situ device or remotely using cameras and radar. This article describes a small, low-resource, deployed spacecraft used as part of a local, multipoint measurement network. A B-field aligned sounding rocket ejects four of these spin-stabilized spacecraft in a cross pattern. In this application, each spacecraft carries two retarding potential analyzers which are used to determine plasma density, flow, and ion temperature. An inertial measurement unit and a light-emitting diode array are used to determine the position and orientation of the devices after deployment. The design of this spacecraft is first described, and then results from a recent test flight are discussed. This flight demonstrated the successful operation of the deployment mechanism and telemetry systems, provided some preliminary plasma measurements in a simple mid-latitude environment, and revealed several design issues.

  6. Miniature Quartz Crystal Microbalance for Spacecraft and Missile Applications

    National Research Council Canada - National Science Library

    Uy, O

    1999-01-01

    Quartz crystal microbalances (QCMs) have been used for over 20 years as contamination monitors in spacecraft to measure film deposition on sensitive surfaces such as optical mirrors, thermal radiators, and solar arrays...

  7. The Impact of Autonomy Technology on Spacecraft Software Architecture

    Science.gov (United States)

    Gamble, E. B., Jr.

    1998-01-01

    Autonomy technology for high-level, closed-loop control of spacecraft offers considerable benefits to space-flight projects. Those benefits can enable whole new classes of missions; however, they are not without cost.

  8. Applicability of ISO 16697 Data to Spacecraft Fire Fighting Strategies

    Science.gov (United States)

    Hirsch, David B.; Beeson, Harold D.

    2012-01-01

    Presentation Agenda: (1) Selected variables affecting oxygen consumption during spacecraft fires, (2) General overview of ISO 16697, (3) Estimated amounts of material consumed during combustion in typical ISS enclosures, (4) Discussion on potential applications.

  9. A multi-spacecraft formation approach to space debris surveillance

    Science.gov (United States)

    Felicetti, Leonard; Emami, M. Reza

    2016-10-01

    This paper proposes a new mission concept devoted to the identification and tracking of space debris through observations made by multiple spacecraft. Specifically, a formation of spacecraft has been designed taking into account the characteristics and requirements of the utilized optical sensors as well as the constraints imposed by sun illumination and visibility conditions. The debris observations are then shared among the team of spacecraft, and processed onboard of a ;hosting leader; to estimate the debris motion by means of Kalman filtering techniques. The primary contribution of this paper resides on the application of a distributed coordination architecture, which provides an autonomous and robust ability to dynamically form spacecraft teams once the target has been detected, and to dynamically build a processing network for the orbit determination of space debris. The team performance, in terms of accuracy, readiness and number of the detected objects, is discussed through numerical simulations.

  10. Micro GC's for Contaminant Monitoring in Spacecraft Air Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this proposal is to create new gas chromatographs (GCs) for contaminant monitoring in spacecraft air that do not require any reagents or special...

  11. Trace Contaminant Monitor for Air in Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A need exists for analyzers that can measure trace contaminants in air on board spacecraft. Toxic gas buildup can endanger the crew particularly during long...

  12. Genome-Wide Scleral Micro- and Messenger-RNA Regulation During Myopia Development in the Mouse.

    Science.gov (United States)

    Metlapally, Ravikanth; Park, Han Na; Chakraborty, Ranjay; Wang, Kevin K; Tan, Christopher C; Light, Jacob G; Pardue, Machelle T; Wildsoet, Christine F

    2016-11-01

    MicroRNA (miRNAs) have been previously implicated in scleral remodeling in normal eye growth. They have the potential to be therapeutic targets for prevention/retardation of exaggerated eye growth in myopia by modulating scleral matrix remodeling. To explore this potential, genome-wide miRNA and messenger RNA (mRNA) scleral profiles in myopic and control eyes from mice were studied. C57BL/6J mice (n = 7; P28) reared under a 12L:12D cycle were form-deprived (FD) unilaterally for 2 weeks. Refractive error and axial length changes were measured using photorefraction and 1310-nm spectral-domain optical coherence tomography, respectively. Scleral RNA samples from FD and fellow control eyes were processed for microarray assay. Statistical analyses were performed using National Institute of Aging array analysis tool; group comparisons were made using ANOVA, and gene ontologies were identified using software available on the Web. Findings were confirmed using quantitative PCR in a separate group of mice (n = 7). Form-deprived eyes showed myopic shifts in refractive error (-2.02 ± 0.47 D; P RNA profiles of test eyes with those of control eyes revealed 54 differentially expressed miRNAs and 261 mRNAs fold-change >1.25 (maximum fold change = 1.63 and 2.7 for miRNAs and mRNAs, respectively) (P < 0.05; minimum, P = 0.0001). Significant ontologies showing gene over-representation (P < 0.05) included intermediate filament organization, scaffold protein binding, detection of stimuli, calcium ion, G protein, and phototransduction. Significant differential expression of Let-7a and miR-16-2, and Smok4a, Prph2, and Gnat1 were confirmed. Scleral mi- and mRNAs showed differential expression linked to myopia, supporting the involvement of miRNAs in eye growth regulation. The observed general trend of relatively small fold-changes suggests a tightly controlled, regulatory mechanism for scleral gene expression.

  13. Nitric oxide in guard cells as an important secondary messenger during stomatal closure

    Directory of Open Access Journals (Sweden)

    Gunja eGayatri

    2013-10-01

    Full Text Available he modulation of guard cell function is the basis of stomatal closure, essential for optimizing water use and CO2 uptake by leaves. Nitric oxide (NO in guard cells plays a very important role as a secondary messenger during stomatal closure induced by effectors, including hormones. For example, exposure to abscisic acid (ABA triggers a marked increase in NO of guard cells, well before stomatal closure. In guard cells of multiple species, like Arabidopsis, Vicia and pea, exposure to ABA or methyl jasmonate or even microbial elicitors (e.g. chitosan induces production of NO as well as reactive oxygen species (ROS. The role of NO in stomatal closure has been confirmed by using NO donors (e.g. SNP and NO scavengers (like cPTIO and inhibitors of NOS (L-NAME or NR (tungstate. Two enzymes: a L-NAME-sensitive, nitric oxide synthase (NOS-like enzyme and a tungstate-sensitive nitrate reductase (NR, can mediate ABA-induced NO rise in guard cells. However, the existence of true NOS in plant tissues and its role in guard cell NO-production are still a matter of intense debate. Guard cell signal transduction leading to stomatal closure involves the participation of several components, besides NO, such as cytosolic pH, ROS, free Ca2+ and phospholipids. Use of fluorescent dyes has revealed that the rise in NO of guard cells occurs after the increase in cytoplasmic pH and ROS. The rise in NO causes an elevation in cytosolic free Ca2+ and promotes the efflux of cations as well as anions from guard cells. Stomatal guard cells have become a model system to study the signalling cascade mechanisms in plants, particularly with NO as a dominant component. The interrelationships and interactions of NO with cytosolic pH, ROS, and free Ca2+ are quite complex and need further detailed examination. While assessing critically the available literature, the present review projects possible areas of further work related to NO-action in stomatal guard cells.

  14. Gingival Toll-like receptor and cytokine messenger RNA levels in equine periodontitis and oral health.

    Science.gov (United States)

    Kennedy, R; Lappin, D F; Dixon, P M; Bennett, D; Riggio, M P

    2017-05-01

    Equine periodontitis is a common and painful condition. However, the disease often goes unnoticed by owners and is thus a major welfare concern. The aetiopathogenesis of the condition remains poorly understood and has been investigated in few studies. The innate immune system is known to play an important role in human periodontitis, but its role in equine periodontitis has not been examined. To quantify the messenger (m)RNA levels of Toll-like receptors (TLRs) and cytokines in gingival tissue from orally healthy horses and those affected by periodontitis. Observational study. Gingival tissue samples were taken post-mortem from 13 horses with no clinical signs of oral disease and 20 horses with periodontitis. mRNA levels of TLR2, TLR4 and TLR9 and cytokines interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), IL-4, IL-6, IL-10, IL-12, IL-17 and interferon-γ (IFN-γ) were determined using quantitative real-time PCR. The statistical significance of results was assessed using appropriate t tests. mRNA levels of all TLRs and cytokines were upregulated in equine periodontitis. Significant increases in mRNA levels of TLR2, TLR9, IL-4, IL-10, IL-12 (P≤0.05) and IFN-γ (P≤0.01) were observed for both unweighted and age-weighted analyses of diseased gingival tissue samples compared with healthy gingival samples. In comparisons of samples of periodontitis lesions with healthy gingival control samples from the same horse, significant increases in mRNA levels of TLR4, TLR9, IL-10, IFN-γ (P≤0.05), TLR2, IL-1β and IL-12p35 (P≤0.01) were observed. This study has provided an initial insight into the involvement of the immune system in equine periodontitis. Increased mRNA levels of TLR2, TLR4 and TLR9 indicate substantial microbial challenge in diseased gingival tissue. A mixed Th1/Th2/Th17 cytokine response is produced in equine periodontitis. Further studies are required to more fully characterise the role of the innate immune system in this disease. © 2016

  15. The Swift and Secret Messenger: John Wilkins’s Mercury and the Paradoxes of Language

    Directory of Open Access Journals (Sweden)

    Łączyńska Klaudia

    2016-12-01

    Full Text Available John Wilkins’s Mercury or the Secret and Swift Messenger: Showing How a Man May with Privacy and Speed Communicate His Thoughts to a Friend at Any Distance was first published in 1641. As a book on cryptography presenting a variety of secret means of communication at a distance it seems to have appeared at just the right time, when the biblical curse of the confusion of tongues was doubled by the curse of political confusion on the brink of the English civil war. However, the book seems to be more than just a detailed account of methods of secret writing; its topic gives the author a chance to present his views on language which he would later develop in his life’s work An Essay towards Real Character and a Philosophical Language published in 1668. The Essay had received much greater critical attention than the early pamphlet, which is usually referred to as merely a prelude to an account of his universal language project. Indeed, in the little book on cryptography, Wilkins already demonstrated his awareness of the conventional character of language and its role within the system of human interactions, as well as advertised a project of philosophical language that would enhance communication between all nations and remedy the curse of Babel. The aim of this paper is to demonstrate that the value of the pamphlet lies also in the insight that it gives into the seventeenth-century debates on the nature of language and into arguments which were often provided, in equal measure, by theology, Hermetic lore, mythology, literature and early modern science. Wilkins’s meticulous recording of the contradictory views and propositions on language produces a sense of methodological inconsistency that leads to ambiguities and paradoxes. However, in the medley of concepts and the collection of linguistic “curiosities” that Mercury presents, a careful reader will discern the growing mistrust of language as a means of representing reality and as a

  16. Passive Plasma Contact Mechanisms for Small-Scale Spacecraft

    Science.gov (United States)

    McTernan, Jesse K.

    Small-scale spacecraft represent a paradigm shift in how entities such as academia, industry, engineering firms, and the scientific community operate in space. However, although the paradigm shift produces unique opportunities to build satellites in unique ways for novel missions, there are also significant challenges that must be addressed. This research addresses two of the challenges associated with small-scale spacecraft: 1) the miniaturization of spacecraft and associated instrumentation and 2) the need to transport charge across the spacecraft-environment boundary. As spacecraft decrease in size, constraints on the size, weight, and power of on-board instrumentation increase--potentially limiting the instrument's functionality or ability to integrate with the spacecraft. These constraints drive research into mechanisms or techniques that use little or no power and efficiently utilize existing resources. One limited resource on small-scale spacecraft is outer surface area, which is often covered with solar panels to meet tight power budgets. This same surface area could also be needed for passive neutralization of spacecraft charging. This research explores the use of a transparent, conductive layer on the solar cell coverglass that is electrically connected to spacecraft ground potential. This dual-purpose material facilitates the use of outer surfaces for both energy harvesting of solar photons as well as passive ion collection. Mission capabilities such as in-situ plasma measurements that were previously infeasible on small-scale platforms become feasible with the use of indium tin oxide-coated solar panel coverglass. We developed test facilities that simulate the space environment in low Earth orbit to test the dual-purpose material and the various application of this approach. Particularly, this research is in support of two upcoming missions: OSIRIS-3U, by Penn State's Student Space Programs Lab, and MiTEE, by the University of Michigan. The purpose of

  17. Project Overview of the Naval Postgraduate School Spacecraft Architecture and Technology Demonstration Experiment

    National Research Council Canada - National Science Library

    Reuer, Charles

    2001-01-01

    The Naval Postgraduate School's current attempt at getting another spacecraft into orbit is focusing on Naval Postgraduate School Spacecraft Architecture and Technology Demonstration Experiment (NPSAT1...

  18. Control System of a Three DOF Spacecraft Simulator by Vectorable Thrusters and Control Moment Gyros

    National Research Council Canada - National Science Library

    Price, William D

    2006-01-01

    ...) Spacecraft Simulator used in the Proximity Operations Simulator Facility, as part of the Naval Postgraduate School's Spacecraft Robotics Laboratory, to simulate autonomous guidance, navigation and control (GNC...

  19. Artificial Intelligence Techniques for Controlling Spacecraft Power System

    OpenAIRE

    Hanaa T. El-Madany; Faten H. Fahmy; Ninet M. A. El-Rahman; Hassen T. Dorrah

    2011-01-01

    Advancements in the field of artificial intelligence (AI) made during this decade have forever changed the way we look at automating spacecraft subsystems including the electrical power system. AI have been used to solve complicated practical problems in various areas and are becoming more and more popular nowadays. In this paper, a mathematical modeling and MATLAB–SIMULINK model for the different components of the spacecraft power system is presented. Also, a control sys...

  20. Description of the Spacecraft Control Laboratory Experiment (SCOLE) facility

    Science.gov (United States)

    Williams, Jeffrey P.; Rallo, Rosemary A.

    1987-01-01

    A laboratory facility for the study of control laws for large flexible spacecraft is described. The facility fulfills the requirements of the Spacecraft Control Laboratory Experiment (SCOLE) design challenge for laboratory experiments, which will allow slew maneuvers and pointing operations. The structural apparatus is described in detail sufficient for modelling purposes. The sensor and actuator types and characteristics are described so that identification and control algorithms may be designed. The control implementation computer and real-time subroutines are also described.