WorldWideScience

Sample records for astron satellites

  1. Measurement of the gravitational redshift effect with RadioAstron satellite

    CERN Document Server

    Birukov, A V; Litvinov, D A; Porayko, N K; Rudenko, V N

    2015-01-01

    RadioAstron satellite admits in principle a testing the gravitational redshift effect with an accuracy of better than $10^{-5}$. It would surpass the result of Gravity Probe A mission at least an order of magnitude. However, RadioAstron's communications and frequency transfer systems are not adapted for a direct application of the non relativistic Doppler and troposphere compensation scheme used in the Gravity Probe A experiment. This leads to degradation of the redshift test accuracy approximately to the level 0.01. We discuss the way to overcome this difficulty and present preliminary results based on data obtained during special observing sessions scheduled for testing the new techniques.

  2. Observatorio Astronómico Nacional, Colombia

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    The Observatorio Astronómico Nacional (OAN) was founded by José Celestino Mutis in the framework of the `Expedicion Botanica' on 20 August 1803. His first astronomer was Francisco Jose de Caldas. By the turn of the century, Julio Garavito worked in celestial mechanics—a crater on the far side of the Moon bears his name....

  3. The RadioAstron Green Bank Earth Station

    Science.gov (United States)

    Ford, H. Alyson; Anderson, Robert; Belousov, Konstantin; Brandt, Joseph J.; Ford, John M.; Kanevsky, Boris; Kovalenko, Anatoly; Kovalev, Yuri Y.; Maddalena, Ronald J.; Sergeev, Sergei; Smirnov, Alexander; Watts, Galen; Weadon, Timothy Lee

    2014-07-01

    We present the design, commissioning, and initial results of the Green Bank Earth Station (GBES), a RadioAstron data downlink station located at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. The GBES uses the modernized and refurbished NRAO 140ft telescope. Antenna optics were refurbished with new motors and drives fitted to the secondary mirror positioning system, and the deformable subreflector was refurbished with a new digital controller and new actuators. A new monitor and control system was developed for the 140ft and is based on that of the Green Bank Telescope (GBT), allowing satellite tracking via a simple scheduling block. Tools were developed to automate antenna pointing during tracking. Data from the antenna control systems and logs are retained and delivered with the science and telemetry data for processing at the Astro Space Center (ASC) of the Lebedev Physical Institute (LPI) of the Russian Academy of Sciences and the mission control centre, Lavochkin Association.

  4. Observatorio Astronómico De Cantabria

    Science.gov (United States)

    Domínguez, R. M.; Carrera, F. J.

    The Astronomical Observatory of Cantabria is a center of the Consejería de Medio Ambiente del Gobierno de Cantabria managed by the Centro de Investigación del Medio Ambiente (CIMA), an autonomous organism which depends on such Consejería. The development of different activities of the Observatory is a joint collaboration between the University of Cantabria and the Agrupación Astronómica Cántabra (AstroCantabria). As part of the University of Cantabria, the Instituto de Física de Cantabria (IFCA, CSIC-UC) is in charge of the direction, management and coordination of scientific, observational, educational and outreach activities of the Observatory. AstroCantabria takes care of the outreach activities for the general public as well as the astronomical observations. In addition, it is responsible for the calibration and maintenance of the astronomical instrumentation of the Observatory. The Astronomical Observatory of Cantabria is located on the Southern edge of the Comunidad Autónoma de Cantabria, on the high plateau of La Lora (Valderredible county), at an altitude of 1,080m, with longitude 3∘ 56 ' 36' W and latitude 42∘ 46 ' 18' N. Rocamundo is the closest town. The Observatory aims to become a center of reference for scientific, observational, educational and public outreach activities in Cantabria. In the near future, an observational proposal system for outside users will be set in place.

  5. The Nuclear Structure of 3C84 with Space VLBI (RadioAstron) Observations

    CERN Document Server

    Giovannini, Gabriele; Savolainen, Tuomas; Nagai, Hiroshi; Giroletti, Marcello; Hada, Kazuhiro; Bruni, Gabriele; Hodgson, Jeffrey; Honma, Mareki; Kino, Motoki; Kovalev, Yuri Y; Krichbaum, Thomas; Lee, Sang-Sung; Lobanov, Andrei; Sohn, Bong Won; Sokolovsky, Kirill; Voitsik, Peter; Zensus, J Anton

    2015-01-01

    The radio galaxy 3C84 is a representative of gamma-ray-bright misaligned active galactic nuclei (AGN) and one of the best laboratories to study the radio properties of subparsec scale jets. We discuss here the past and present activity of the nuclear region within the central 1pc and the properties of subparsec-sized components C1, C2 and C3. We compare these results with the high resolution space-VLBI image at 5GHz obtained with the RadioAstron satellite and we shortly discuss the possible correlation of radio emission with the gamma-ray emission.

  6. Modelos de Refracción Astronómica

    OpenAIRE

    Prieto Morin, Juan Francisco; Velasco Gomez, Jesus

    2011-01-01

    Se resumen en esta monografía la teoría básica sobre refracción astronómica para ser aplicada a observaciones topográficas a astros. Se comentan también los diferentes modelos matemáticos existentes hasta la fecha.

  7. Model for the coma of Comet Halley, based on the Astron ultraviolet spectrophotometry

    International Nuclear Information System (INIS)

    The development of a model of the Comet Halley coma from spectral and photometric data is described. Spectra in the 1500-3500 A range and photometric scans at the 3085 A and 2190 A in the (0-0) band of the OH and CO(+) molecules were obtained by the UV telescope of the satellite Astron on December 3, 13, and 23, 1985. Surface-brightness profiles of the coma in the (0-0) band of OH, NH, and CS molecules are derived. The source and formation of these molecules, the lifetime of their radicals, the radial velocity of their parent molecules, and the water-molecule sublimation rate are computed and examined. The basic characteristics of the comet observed from the UV data are compared to the properties of other comets. It is observed that Comet Halley is similar to other large short-period comets. 29 references

  8. Alfabetización astronómica

    Science.gov (United States)

    Tignanelli, H.

    A fines de 1991, en una revista de educación en ciencias, José L. Sérsic reflexionaba acerca de los problemas que enfrentaría la enseñanza de los conocimientos astronómicos en nuestro país, en los umbrales del Siglo XXI. Entonces postulaba como un objetivo mínimo, que los jóvenes deberían mostrar signos claros de que se hallan astronómicamente alfabetizados. Era el año en que se realizaba por primera vez una Asamblea General de I.A.U. en Buenos Aires, una oportunidad de singulares características para la comunidad astronómica local y, simultáneamente el comienzo de un cambio radical en la estructura del sistema educativo argentino. ?`Contempla ese cambio el objetivo que postulara Sérsic? ?`Estamos en condiciones de afirmar que estamos en camino de lograrlo? ?`Con qué parámetros?. Presentamos aquí un panorama general sobre algunas de las acciones realizadas en función de alcanzar esa alfabetización científica, analizando exclusivamente la actividad de enseñanza hasta el nivel universitario, sin detenernos en el mismo, ya que lo consideramos una instancia superior e independiente de aquella alfabetización. Tampoco nos referiremos a la tarea de difusión, divulgación o popularización de la Astronomía, ya que su condición de asistemática y subjetiva no es evaluable en términos de la formación integral de un individuo.

  9. RadioAstron gravitational redshift experiment: status update

    CERN Document Server

    Litvinov, D A; Bartel, N; Belousov, K G; Bietenholz, M; Biriukov, A V; Cimo, G; Duev, D A; Gurvits, L I; Gusev, A V; Haas, R; Kauts, V L; Kanevsky, B Z; Kovalenko, A V; Kronschnabl, G; Kulagin, V V; Lindqvist, M; Calves, G Molera; Neidhardt, A; Ploetz, C; Pogrebenko, S V; Porayko, N K; Rudenko, V N; Smirnov, A I; Sokolovsky, K V; Stepanyants, V A; Yang, J; Zakhvatkin, M V

    2016-01-01

    A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of $4\\times10^{-4}$. We expect to reach $2.5\\times10^{-5}$ with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission.

  10. The abundance of ammonia in Comet P/Halley derived from ultraviolet spectrophotometry of NH by ASTRON and IUE

    Science.gov (United States)

    Feldman, P. D.; Fournier, K. B.; Grinin, V. P.; Zvereva, A. M.

    1993-01-01

    From an analysis of the spatial profiles of both the NH and OH UV emissions observed by the ASTRON satellite, the ratio of ammonia-to-water production rates in Comet Halley on April 9, 1986 is derived and found to lie in the range of 0.44-0.94 percent. In order to compare this result with those based on both ground-based and in situ observations made on other dates during the 1985-1986 apparition of the comet, the IUE observational data base for December 1985 and March-April 1986 is used to evaluate the ratio of NH to OH column density in the IUE field of view and thus constrain the long-term behavior of this ratio. The IUE data base indicates that, to within a factor of 2, the ammonia-to-water production rate ratio is the same for a small sample of moderately bright comets observed recently.

  11. SPECKLE INTERFEROMETRY AT THE OBSERVATORIO ASTRON ́ OMICO NACIONAL. VI.

    Directory of Open Access Journals (Sweden)

    V. G. Orlov

    2015-01-01

    Full Text Available Presentamos mediciones de estrellas dobles mediante interferometría de motas, obtenidas en agosto de 2010 con el telescopio de 1.5 m y en mayo de 2010 con el telescopio de 2.1 m del Observatorio Astronómico Nacional en SPM (México. Reportamos los resultados de 331 mediciones de 321 sistemas, con una magnitud límite para las primarias de V = 12.9. Las separaciones angulares medidas están comprendidas entre 0.13 y 7.39 segundos de arco. 269 pares resultaron tener separaciones de menos de 1 segundo de arco. El error medio en las separaciones es de 0.032 segundos de arco, y en los ángulos de posición, 2 grados. La ambigüedad usual de 180 grados en los ángulos de posición fue corregida para la mayoría de ellos usando observaciones de otros autores.

  12. Observatorio Astronómico Nacional. Ciencia y Memoria para la Sociedad

    OpenAIRE

    Badawi, Halim; Roa Triana, Julian; Torres Carreño, Guillermo Andrés; Cortés, Diego; Castell, Edmon

    2008-01-01

    Observatorio Astronómico Nacional hace parte del Sistema de Patrimonio Cultural y Museos SPM. Esta infografía contiene una cronología del Observatorio, eventos importantes de la historia de Colombia que se desarrollaron en este espacio y describe el proyecto de Sistema de Museos.

  13. Historia de la Ciencia árabe: los sitemas astronómicos

    OpenAIRE

    Torroja, J. M.

    1981-01-01

    En un curso de conferencias sobre Historia de la Ciencia Árabe no podía faltar una sobre sus ideas acerca de los sistemas astronómicos, que tanta importancia tuvieron a lo largo de los siglos en la cultura árabe, primero en Oriente y más tarde en España, bajo el mecenazgo de los Califas de Bagdad y de Córdoba. Esta ciencia astronómica árabe sería recogida por Alfonso el Sabio en sus Libros del Saber de Astronomía y pasaría a Europa a través de las traducciones efectuadas tanto en las escue...

  14. Gravitational Redshift Experiment with the Space Radio Telescope RadioAstron

    CERN Document Server

    Litvinov, D; Belousov, K; Bietenholz, M; Biriukov, A; Fionov, A; Gusev, A; Kauts, V; Kovalenko, A; Kulagin, V; Poraiko, N; Rudenko, V

    2015-01-01

    A unique test of general relativity is possible with the space radio telescope RadioAstron. The ultra-stable on-board hydrogen maser frequency standard and the highly eccentric orbit make RadioAstron an ideal instrument for probing the gravitational redshift effect. Large gravitational potential variation, occurring on the time scale of $\\sim$24 hr, causes large variation of the on-board H-maser clock rate, which can be detected via comparison with frequency standards installed at various ground radio astronomical observatories. The experiment requires specific on-board hardware operating modes and support from ground radio telescopes capable of tracking the spacecraft continuously and equipped with 8.4 or 15 GHz receivers. Our preliminary estimates show that $\\sim$30 hr of the space radio telescope's observational time are required to reach $\\sim 2\\times10^{-5}$ accuracy in the test, which would constitute a factor of 10 improvement over the currently achieved best result.

  15. VIII Olimpíada Brasileira de Astronomia e Astronáutica

    Science.gov (United States)

    Garcia Canalle, João Batista; Villas da Rocha, Jaime Fernando; Wuensche de Souza, Carlos Alexandre; Pereira Ortiz, Roberto; Aguilera, Nuricel Villalonga; Padilha, Maria De Fátima Catta Preta; Pessoa Filho, José Bezerra; Soares Rodrigues, Ivette Maria

    2007-07-01

    Neste trabalho apresentamos as motivações pelas quais organizamos, em conjunto, pela primeira vez, a Olimpíada Brasileira de Astronomia incluindo a Astronáutica, em colaboração com a Agência Espacial Brasileira. Esta ampliação contribuiu para atrair ainda mais alunos, professores, escolas e patrocinadores para participarem desta Olimpíada. Em 2005 participaram da VIII Olimpíada Brasileira de Astronomia e Astronáutica (VIII OBA) 187.726 alunos distribuídos por 3.229 escolas, pertencentes a todos os estados brasileiros, incluindo o Distrito Federal. O crescimento em número de alunos participantes foi 52,4% maior do que em 2004. Em abril de 2005 organizamos, em Itapecerica da Serra, SP, um curso para os 50 alunos previamente selecionados e participantes da VII OBA e ao final selecionamos, dentre eles, uma equipe de 5 alunos, os quais representaram o Brasil na X Olimpíada Internacional de Astronomia, na China, em outubro de 2005. Ganhamos, pela primeira vez, uma medalha de ouro naquele evento. Em Agosto de 2005, organizamos a VIII Escola de Agosto para 50 alunos e respectivos professores, em Águas de Lindóia, SP, juntamente com a XXXI reunião anual da Sociedade Astronômica Brasileira (SAB). Em novembro de 2005 realizamos a I Jornada Espacial, em São José dos Campos, com 22 alunos e 22 professores selecionados dentre os participantes que melhores resultados obtiveram nas questões de Astronáutica da VIII OBA. Neste trabalho detalhamos os resultados da VIII OBA bem como as ações subseqüentes.

  16. Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron

    Science.gov (United States)

    Johnson, Michael D.; Kovalev, Yuri Y.; Gwinn, Carl R.; Gurvits, Leonid I.; Narayan, Ramesh; Macquart, Jean-Pierre; Jauncey, David L.; Voitsik, Peter A.; Anderson, James M.; Sokolovsky, Kirill V.; Lisakov, Mikhail M.

    2016-03-01

    Earth-space interferometry with RadioAstron provides the highest direct angular resolution ever achieved in astronomy at any wavelength. RadioAstron detections of the classic quasar 3C 273 on interferometric baselines up to 171,000 km suggest brightness temperatures exceeding expected limits from the “inverse-Compton catastrophe” by two orders of magnitude. We show that at 18 cm, these estimates most likely arise from refractive substructure introduced by scattering in the interstellar medium. We use the scattering properties to estimate an intrinsic brightness temperature of 7× {10}12 {{K}}, which is consistent with expected theoretical limits, but which is ˜15 times lower than estimates that neglect substructure. At 6.2 cm, the substructure influences the measured values appreciably but gives an estimated brightness temperature that is comparable to models that do not account for the substructure. At 1.35 {{cm}}, the substructure does not affect the extremely high inferred brightness temperatures, in excess of {10}13 {{K}}. We also demonstrate that for a source having a Gaussian surface brightness profile, a single long-baseline estimate of refractive substructure determines an absolute minimum brightness temperature, if the scattering properties along a given line of sight are known, and that this minimum accurately approximates the apparent brightness temperature over a wide range of total flux densities.

  17. Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron

    CERN Document Server

    Johnson, Michael D; Gwinn, Carl R; Gurvits, Leonid I; Narayan, Ramesh; Macquart, Jean-Pierre; Jauncey, David L; Voitsik, Peter A; Anderson, James M; Sokolovsky, Kirill V; Lisakov, Mikhail M

    2016-01-01

    Earth-space interferometry with RadioAstron provides the highest direct angular resolution ever achieved in astronomy at any wavelength. RadioAstron detections of the classic quasar 3C273 on interferometric baselines up to 171,000 km suggest brightness temperatures exceeding expected limits from the "inverse-Compton catastrophe" by two orders of magnitude. We show that at 18 cm, these estimates most probably arise from refractive substructure introduced by scattering in the interstellar medium. We use the scattering properties to estimate an intrinsic brightness temperature of 7*10^12 K, which is consistent with expected theoretical limits, but which is ~15 times lower than estimates that neglect substructure. At 6 cm, the substructure influences the measured values appreciably but gives an estimated brightness temperature that is comparable to models that do not account for the substructure. At 1.3 cm, the substructure does not affect the extremely high inferred brightness temperatures, in excess of 10^13 K....

  18. Practical Astronomical Activities during Daytime. (Spanish Title: Actividades Astronómicas Prácticas Diurnas.) Atividades Astronômicas Práticas Diurnas

    Science.gov (United States)

    Jackson, Eric

    2009-12-01

    These daytime astronomy activities arose from research done in New Zealand by a group of teachers and astronomers into the problems of teaching astronomy. This showed that it was generally regarded as a difficult subject to take, traditionally relying on books, films and models. The fortunate may have had a visit to an observatory or planetarium, the adventurous may have attempted an outdoor evening viewing session, which sometimes had weather-related difficulties. The problem of not having many 'hands-on' activities, the feelings of inadequate knowledge, the felt need for astronomical equipment and expertise become too daunting for many teachers to do the subject justice. If astronomy was to be taught then a way around these difficulties needed to be found. Our group, working with teachers and children using the constructivism teaching approach, found that the principles of astronomy could be discovered during the day when the students are at school. Working co-operatively they measured and recorded observations of their shadows caused by the motions and interactions of the nearest star, the Sun (Sol), and our planet, Earth. Because children were involved so personally they were much more interested in the results of the study. Astronomy became enthralling and challenging for both teacher and class after applying their daytime experiences to night time viewing at home and reporting back to class. Estas actividades astronómicas diurnas surgieron de una investigación hecha en NuevaZelandia por un grupo de maestros y astrónomos sobre los problemas de la enseñanza de la Astronomía. Este trabajo mostró que la Astronomía es generalmente considerada una disciplina difícil de enseñar, y tradicionalmente basada en libros, filmes y modelos. Los más afortunados pueden haber efectuado alguna visita a un observatorio o planetario, y los más aventajados pueden tal vez haber intentado una sesión de observación nocturna, las cuales sufren a veces de dificultades

  19. Space-VLBI with RadioAstron: new correlator capabilities at MPIfR

    CERN Document Server

    Bruni, G; Alef, W; Lobanov, A; Zensus, J A

    2015-01-01

    DiFX is a correlator for VLBI data based on the FX architecture (first Fourier transform and then cross-multiply). DiFX is a free licensed software written in C++, developed and maintened by an international group of programmers. A new DiFX version (dra) has been developed at Max-Planck-Institut f\\"ur Radioastronomie (MPIfR), in order to manage the correlation of a space-based antenna with ground stations. The dra version is running on the High Performance Computer cluster (HPC) in Bonn, and it is used for the data processing of the three AGN imaging RadioAstron Key Science Projects ongoing, based at the MPIfR.

  20. Theoretical Study of E-Layer and Plasma Behaviour in Astron

    International Nuclear Information System (INIS)

    The injection, equilibrium, and stability of the E-layer and confined plasma in Astron ate Investigated. Self-consistent equilibrium configurations for a collisionless E -layer and an ideal plasma fluid have been obtained from a numerical solution of Ampere's law, using various models for both the E-layer and the plasma pressure profiles. The degree of field reversal and the shape of the magnetic well can be varied so as to obtain equilibria with favourable stability properties. The stability of an E-layer, alone or in conjunction with a cold background plasma, has been analysed for modes with wavelengths less than or comparable to E-layer dimensions. The results are in good qualitative agreement with experimental observations on the precession, negative-mass, and plasma hybrid modes. The most important stabilizing mechanism is seen to be energy spread in the E-layer. The stability of the confined plasma is investigated using the magnetohydiodynamic (MHD) energy principle. A numerical solution of the eigenvalue problem, which arises from minimization of the potential energy, allows the MHD-stability of any of the equilibrium models used to be tested. The limiting plasma pressure is determined, and specific numerical examples of stable equilibria are given. A time -dependent numerical model of the Astron, with which injection and trapping can be studied in detail, has also been developed. The effects due to the resistors, neutralization, and the ambient plasma have been included. The model is axially symmetric. The E-layer electrons are simulated by many thousands of finite-size super-particles, which move in the r-z domain and have velocity components vr, vθ , and vz. The model is relativistic and the electromagnetic fields are obtained by solving four wave equations — three for the vector potential and one for the scalar potential. The E-layer and plasma currents and the current induced in the resistor wires are included in the above field equations. The

  1. The Guieloa Adaptive Optics System for the Observatorio Astronómico Nacional

    Directory of Open Access Journals (Sweden)

    A.M. Watson

    2007-01-01

    Full Text Available Se describen los avances para construir un sistema de ptica adaptativa para el telescopio de 2.1-metros del Observatorio Astron mico Nacional en la Sierra de San Pedro M rtir. El sistema utilizar un espejo deformable de tipo bimorfo de 19 elementos montado sobre una plataforma articulada y un sensor de frente de onda tipo curvatura para estrellas gu a naturales. Guieloa tendr dos modos de operaci n. En modo de ptica adaptativa se espera que proporcionar una correcci n excelente en longitudes de onda mayores a 1.0 m y una correcci n buena entre 0.6 y 0.9 m dependiendo de las condiciones del seeing, aunque la cobertura del cielo ser restringida. En el modo de ptica activa y guiado r pido se espera que proporcionar im genes en el l mite del seeing natural o mejor, y con una cobertura de cielo mucho mayor. Actualmente el sistema se encuentra en la fase de pruebas en el laboratorio y se espera que sea entregado en el observatorio en 2009

  2. The Nuclear Structures of Cen A, M87 and 3C273 at Very High Resolution with RadioAstron and the LBA

    Science.gov (United States)

    Reynolds, Cormac; Lobanov, Andrei; Giovannini, Gabriele; Orienti, Monica; Tingay, Steven; Kovalev, Yuri; Krichbaum, Thomas P.; Savolainen, Tuomas; Anderson, James M.

    2013-10-01

    We request 30 hours of LBA time to perform perigee imaging observations with the RadioAstron orbiting VLBI antenna. RadioAstron provides a unique opportunity to image nearby AGN at unprecedented resolution and will allow us to address fundamental questions related to the jet formation process in AGN. The proposed observations can reveal the nuclear structures in these objects down to scales of just a few Schwarzschild radii, a resolution that will allow us to compare observational data on the region where the jets are launched and collimated to the predictions of analytical models and simulations.

  3. RadioAstron Observations of the Quasar 3C273: A Challenge to the Brightness Temperature Limit

    Science.gov (United States)

    Kovalev, Y. Y.; Kardashev, N. S.; Kellermann, K. I.; Lobanov, A. P.; Johnson, M. D.; Gurvits, L. I.; Voitsik, P. A.; Zensus, J. A.; Anderson, J. M.; Bach, U.; Jauncey, D. L.; Ghigo, F.; Ghosh, T.; Kraus, A.; Kovalev, Yu. A.; Lisakov, M. M.; Petrov, L. Yu.; Romney, J. D.; Salter, C. J.; Sokolovsky, K. V.

    2016-03-01

    Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of 1011.5 K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of 1013 K are inaccessible using ground-based very long baseline interferometry (VLBI) at any wavelength. We present observations of the quasar 3C 273, made with the space VLBI mission RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as small as 26 μas (2.7 light months) and brightness temperature in excess of 1013 K. These measurements challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive black holes and require a much higher Doppler factor than what is determined from jet apparent kinematics.

  4. RadioAstron Observations of the Quasar 3C273: a Challenge to the Brightness Temperature Limit

    CERN Document Server

    Kovalev, Y Y; Kellermann, K I; Lobanov, A P; Johnson, M D; Gurvits, L I; Voitsik, P A; Zensus, J A; Anderson, J M; Bach, U; Jauncey, D L; Ghigo, F; Ghosh, T; Kraus, A; Kovalev, Yu A; Lisakov, M M; Petrov, L Yu; Romney, J D; Salter, C J; Sokolovsky, K V

    2016-01-01

    Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of $10^{11.5}$ K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of $10^{13}$ K are inaccessible using ground-based very long baseline interferometry (VLBI) at any wavelength. We present observations of the quasar 3C273, made with the space VLBI mission RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as small as 26 $\\mu$as (2.7 light months) and brightness temperature in excess of $10^{13}$ K. These measurements challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive black holes and require much higher jet speeds than are observed.

  5. RadioAstron -- a Telescope with a Size of 300 000 km: Main Parameters and First Observational Results

    CERN Document Server

    Kardashev, N S; 10.1134/S1063772913030025

    2013-01-01

    The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna ground-space radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of format...

  6. Recent Site Testing Campaign at the Observatorio Astronómico Nacional in San Pedro Mártir

    Directory of Open Access Journals (Sweden)

    R. Michel

    2003-01-01

    Full Text Available Hemos llevado a cabo un nuevo programa para medir el seeing en el Observatorio Astronómico Nacional en San Pedro Mártir. Los resultados obtenidos durante un período de dos años, arrojan una calidad de imagen con mediana de 0.57 segundos de arco y un primer cuartil de 0.46 segundos de arco. Mostramos también que el seeing puede ser muy estable durante toda la noche bajo condiciones excelentes. Las mejores medidas arrojan una mediana de 0.37 segundos de arco, obtenidas de observaciones continuas durante casi nueve horas. Nuestros resultados son comparados con un estudio previo del sitio, encontrándose resultados muy similares.

  7. Recuperación de información astronómica : nuevas perspectivas de análisis de la cartografía celeste histórica

    OpenAIRE

    Alonso Lifante, María Pilar

    2014-01-01

    La mejora de la descripción de contenidos de recursos especializados en general, y de astronómicos en particular, es todavía una asignatura pendiente de las Ciencias de la Documentación. Actualmente existe gran cantidad de información astronómica histórica de interés recogida en diversos tipos de documentos que se conservan en archivos y bibliotecas astronómicas de todo el mundo. Entre estos documentos se encuentran los denominados catálogos y atlas de estrellas, así como imágenes astrofotogr...

  8. Control remoto del sistema B+G del Observatorio Astronómico del Montsec: monitorización de funciones.

    OpenAIRE

    Clavero Quílez, Javier

    2006-01-01

    En el año 2001 la Generalitat de Cataluña creó el Consorcio del Montsec para la ejecución del proyecto Montsec Sostenible. En el marco de este proyecto y mediante la colaboración de diversos departamentos de las Universidades públicas de Cataluña, entre las cuales se encuentran los departamentos de Física Aplicada (FA) y de Física e Ingeniería Nuclear (FEN), de la Universidad Politécnica de Cataluña (UPC), se creó el Parque Astronómico del Montsec (PAM). El Observatorio Astronómico del Mo...

  9. Parque Astron\\'omico de Atacama: An ideal site for millimeter, sub-millimeter, and mid-infrared astronomy

    CERN Document Server

    Bustos, Ricardo; Otárola, Angel; Nagar, Neil

    2014-01-01

    The area of Chajnantor, at more than 5000 meters altitude in northern Chile, offers unique atmospheric and operational conditions which arguably make it the best site in the world for millimeter, sub-millimeter, and mid-infrared observatories. Long-term monitoring of the precipitable water vapor (PWV) column on the Chajnantor plateau has shown its extreme dryness with annual median values of 1.1 mm. Simultaneous measurements of PWV on the Chajnantor plateau (5050 m) and on Cerro Chajnantor (5612 m) show that the latter is around 36% lower under normal atmospheric conditions and up to 80% lower than the plateau in the presence of temperature inversion layers. Recently, the Government of Chile has consolidated the creation of the Parque Astron\\'omico de Atacama (Atacama Astronomical Park), an initiative of the Chilean Commission for Science and Technology (CONICYT). This new Parque offers an opportunity for national and international projects to settle within its boundaries, gain access to an extremely dry site...

  10. Parque Astronómico de Atacama: An Ideal Site for Millimeter, Submillimeter, and Mid-Infrared Astronomy

    Science.gov (United States)

    Bustos, R.; Rubio, M.; Otárola, A.; Nagar, N.

    2014-12-01

    The area of Chajnantor, at more than 5000 m altitude in northern Chile, offers unique atmospheric and operational conditions which arguably make it the best site in the world for millimeter, submillimeter, and mid-infrared observatories. Long-term monitoring of the precipitable water vapor (PWV) column on the Chajnantor plateau has shown its extreme dryness with annual median values of 1.1 mm. Simultaneous measurements of PWV on the Chajnantor plateau (5050 m) and on Cerro Chajnantor (5612 m) show that the latter is around 36% lower under normal atmospheric conditions and up to 80% lower than the plateau in the presence of temperature inversion layers. Recently, the Government of Chile has consolidated the creation of the Parque Astronómico de Atacama (Atacama Astronomical Park), an initiative of the Chilean Commission for Science and Technology (CONICYT). This new park offers an opportunity for national and international projects to settle within its boundaries, gain access to an extremely dry site that is suitable for observations over a broad spectral range, especially in the millimeter to mid-infrared wavelengths, and benefit from operational and logistical support within a secure legal framework.

  11. RadioAstron Studies of the Nearby, Turbulent Interstellar Plasma With the Longest Space-Ground Interferometer Baseline

    CERN Document Server

    Smirnova, T V; Popov, M V; Gwinn, C R; Anderson, J M; Andrianov, A S; Bartel, N; Deller, A; Johnson, M D; Joshi, B C; Kardashev, N S; Karuppusamy, R; Kovalev, Y Y; Kramer, M; Soglasnov, V A; Zensus, J A; Zhuravlev, V I

    2014-01-01

    RadioAstron space-ground VLBI observations of the pulsar B0950+08, conducted with the 10-m space radio telescope in conjunction with the Arecibo 300-m telescope and Westerbork Synthesis Radio Telescope at a frequency of 324 MHz, were analyzed in order to investigate plasma inhomogeneities in the direction of this nearby pulsar. The observations were conducted at a spacecraft distance of 330,000 km, resulting in a projected baseline of 220,000 km, providing the greatest angular resolution ever achieved at meter wavelengths. Our analysis is based on fundamental behavior of structure and coherence functions. We find that the pulsar shows scintillation on two frequency scales, both much less than the observing frequency; but modulation is less than 100%. We infer that the scattering is weak, but a refracting wedge disperses the scintillation pattern. The refraction angle of this "cosmic prism" is measured as theta_0=1.1 - 4.4 mas, with the refraction direction being approximately perpendicular to the observer vel...

  12. Probing the Innermost Regions of AGN Jets and Their Magnetic Fields with RadioAstron. I. Imaging BL Lacertae at 21 Microarcsecond Resolution

    Science.gov (United States)

    Gómez, José L.; Lobanov, Andrei P.; Bruni, Gabriele; Kovalev, Yuri Y.; Marscher, Alan P.; Jorstad, Svetlana G.; Mizuno, Yosuke; Bach, Uwe; Sokolovsky, Kirill V.; Anderson, James M.; Galindo, Pablo; Kardashev, Nikolay S.; Lisakov, Mikhail M.

    2016-02-01

    We present the first polarimetric space very long baseline interferometry (VLBI) imaging observations at 22 GHz. BL Lacertae was observed in 2013 November 10 with the RadioAstron space VLBI mission, including a ground array of 15 radio telescopes. The instrumental polarization of the space radio telescope is found to be less than 9%, demonstrating the polarimetric imaging capabilities of RadioAstron at 22 GHz. Ground-space fringes were obtained up to a projected baseline distance of 7.9 Earth diameters in length, allowing us to image the jet in BL Lacertae with a maximum angular resolution of 21 μas, the highest achieved to date. We find evidence for emission upstream of the radio core, which may correspond to a recollimation shock at about 40 μas from the jet apex, in a pattern that includes other recollimation shocks at approximately 100 and 250 μas from the jet apex. Polarized emission is detected in two components within the innermost 0.5 mas from the core, as well as in some knots 3 mas downstream. Faraday rotation analysis, obtained from combining RadioAstron 22 GHz and ground-based 15 and 43 GHz images, shows a gradient in rotation measure and Faraday-corrected polarization vector as a function of position angle with respect to the core, suggesting that the jet in BL Lacertae is threaded by a helical magnetic field. The intrinsic de-boosted brightness temperature in the unresolved core exceeds 3× {10}12 K, suggesting, at the very least, departure from equipartition of energy between the magnetic field and radiating particles.

  13. OH maser observations using the Russian interferometric network ``Quasar'' in preparation for scientific observations with the space mission RadioAstron.

    Science.gov (United States)

    Litovchenko, I. D.; Alakoz, A. V.; Kostenko, V. I.; Lihachev, S. F.; Finkelstein, A. M.; Ipatov, A. V.

    2012-07-01

    We present results of a VLBI experiment at a wavelength of 18 cm, which simulates the ground-space interferometer with space link to RadioAstron. An array of five antennas was used, four of them are located in the Russian Federation, plus the the 32-m radio telescope in Medicine (Italy). The 22-m radio telescope in Pushchino (Moscow Region) acted in place of the space arm. It has an effective area of 100 square meters. The three other Russian 32-m antennas are operated by the Institute of Applied Astronomy RAS; they are located at Badary, Svetloe and Zelenchukskaya (interferometer network ``Quasar''). The maximum base-line, Badary-Svetloe, was about 4402 km, providing an angular resolution of about 0.009 arc seconds at a wavelength of 18 cm. The duration of the experiment was 10 hours on 02/03 February 2011. The program of observations included quasars 3C273, 3C279, 3C286 and the maser source - W3(OH). W3(OH) was observed only by the Russian telescopes and was investigated at the frequency of the 1665 MHz main line. The data were recorded on the MK5 recorder (32-m radio telescopes) and the RDR system (RadioAstron Digital Recorder) in Pushchino. The low SEFD (system equivalence of flux density) of Pushchino emulated the RadioAstron antenna. Correlation was performed with the universal software correlator of the AstroSpace Center of Lebedev Physical Institute. The correlator output format is compatible with that used by the AIPS package, which was used for data analysis. After analyzing the correlated data we obtained relative coordinates of the maser components. The main results are tabulated and presented in the figures. The data quality is sufficient for astrophysical analysis and comparison with previous observations of maser source W3(OH) on VLBI networks EVN and VLBA.

  14. Análise dos Conceitos Astronômicos Apresentados por Professores de Algumas Escolas Estaduais Brasileiras

    Science.gov (United States)

    Voelzke, Marcos Rincon; Gonzaga, Edson Pereira

    2011-12-01

    A razão para o desenvolvimento deste trabalho baseia-se no fato de que muitos professores da Educação Básica (EB) não lidam com conceitos relacionados à astronomia, e quando o fazem eles simplesmente seguem livros didáticos que podem conter erros conceituais. Como é de conhecimento geral a astronomia é um dos conteúdos a serem ensinados na EB fazendo parte dos Parâmetros Curriculares Nacionais e das Propostas Curriculares do Estado de São Paulo, mas é um fato, que vários pesquisadores apontam, a existência de muitos problemas no ensino da astronomia. Com o propósito de minimizar algumas dessas deficiências foi realizado um trabalho de pesquisa com a utilização de questionários pré e pós pesquisa, para tanto foi desenvolvido um Curso de Extensão Universitária para professores da Diretoria de Ensino Regional (DE) que abrange Mauá, Ribeirão Pires e Rio Grande da Serra (no Estado de São Paulo) com os seguintes objetivos: levantar concepções alternativas; subsidiar os professores por meio de palestras, debates e workshops, e verificar o sucesso da aprendizagem após o curso, adotando-se como referência, para a análise dos resultados, os dicionários de Língua Portuguesa (FERREIRA, 2004) e Enciclopédico de Astronomia e Astronáutica (MOURĀO, 1995). Portanto, dezesseis questões foram aplicadas antes e após o curso, assim pode-se verificar após a pesquisa que 100,0% dos professores sabiam os nomes das fases da Lua, 97,0% entenderam que o Sistema Solar é composto por oito planetas, 78,1% foram capazes de explicar como ocorre um eclipse lunar, um eclipse solar e um solstício, 72,7% sabiam como explicar a ocorrência das estações do ano; 64,5% explicaram corretamente a ocorrência do equinócio, 89,7% foram capazes de definir adequadamente o termo cometa; 63,6% definiram asteróide, 54,5% meteoro, 58,1% galáxia, e 42,4% planeta. Os resultados obtidos indicam uma aprendizagem significativa por parte dos participantes.

  15. Escuela de literatura i filosofía. programa de jeografía astronómica, física i política

    OpenAIRE

    Pinzón, José Rafael

    2009-01-01

    Nociones preliminares de geometría, necesarias para el estudio de la geografía.Geografía astronómica: Parte histórica; Parte científica; Aspectos del cielo; Estrellas fijas; Distancia de los planetas; Planetas; Planetas superiores; Planetas telescópicos que se encuentran entre Marte y Júpiter: Juno, Céres, Pálas, Vesta; Júpiter y sus satélites; Saturno, sus satélites y anillos; Herschell o Urano y sus satélites; Leverrier o Neptuno; Leyes de Kepler; Atracción universal; Masas planetarias; La ...

  16. Neptunian Satellites observed with Keck AO system

    Science.gov (United States)

    Marchis, F.; Urata, R.; de Pater, I.; Gibbard, S.; Hammel, H. B.; Berthier, J.

    2004-05-01

    The Neptunian system was observed on 9 different nights between July 2002 and October 2003 with the 10-m Keck telescope on Mauna Kea, Hawaii, and its facility instrument NIRC2 coupled with the Adaptive Optics system. Data were recorded in J (1.2μ m), and H (2.2μ m) bands. The angular resolution achieved on a one-minute integration time image is 0.50 arcsec, corresponding to a spatial resolution of 1100 km. The images display small structures such as the rings (de Pater et al. 2004), clouds in the atmosphere (Gibbard et al. 2003), and inner satellites, mainly Proteus, Larissa, Galatea, Despina, and Thalassa. On the 40 images, the positions and intensities of the satellites detected were accurately measured fitting the signal with a gaussian profile. The center of Neptune was obtained by fitting the disk position with an ellipse. After correcting for the detector distortion, we compared the satellite positions with the predicted ones delivered by several ephemerides. We used the JPL (NEP016 + NEP022 + DE405) and two IMCCE ephemerides, an old version (VSOP87+Owen et al., 1991) and a more recent one (DE405+Le Guyader et al., 1993). All cases, we confirmed the presence of an apparent shift between the predicted and the observed positions. Table 1 (see http://astron.berkeley.edu/ fmarchis/Science/Neptune/Satellites/) summarizes the mean distance of the shift for satellites most frequently observed and the various ephemerides. In this presentation, we will report the positions of the satellites, and present their color and possible photometric variations derived from the observations. This work has been partially supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 9876783.

  17. Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. I. Imaging BL Lacertae at 21 microarcsecond resolution

    CERN Document Server

    Gómez, José L; Bruni, Gabriele; Kovalev, Yuri Y; Marscher, Alan P; Jorstad, Svetlana G; Mizuno, Yosuke; Bach, Uwe; Sokolovsky, Kirill V; Anderson, James M; Galindo, Pablo; Kardashev, Nikolay S; Lisakov, Mikhail M

    2016-01-01

    We present the first polarimetric space VLBI imaging observations at 22 GHz. BL Lacertae was observed in 2013 November 10 with the RadioAstron space VLBI mission, including a ground array of 15 radio telescopes. The instrumental polarization of the space radio telescope is found to be within 9%, demonstrating the polarimetric imaging capabilities of RadioAstron at 22 GHz. Ground-space fringes were obtained up to a projected baseline distance of 7.9 Earth's diameters in length, allowing us to image the jet in BL Lacertae with a maximum angular resolution of 21 $\\mu$as, the highest achieved to date. We find evidence for emission upstream of the radio core, which may correspond to a recollimation shock at about 40 $\\mu$as from the jet apex, in a pattern that includes other recollimation shocks at approximately 100 $\\mu$as and 250 $\\mu$as from the jet apex. Polarized emission is detected in two components within the innermost 0.5 mas from the core, as well as in some knots 3 mas downstream. Faraday rotation analy...

  18. Satellite Geomagnetism

    OpenAIRE

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade. The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite c...

  19. Centriolar satellites

    DEFF Research Database (Denmark)

    Tollenaere, Maxim A X; Mailand, Niels; Bekker-Jensen, Simon

    2015-01-01

    Centriolar satellites are small, microscopically visible granules that cluster around centrosomes. These structures, which contain numerous proteins directly involved in centrosome maintenance, ciliogenesis, and neurogenesis, have traditionally been viewed as vehicles for protein trafficking...... highlight newly discovered regulatory mechanisms targeting centriolar satellites and their functional status, and we discuss how defects in centriolar satellite components are intimately linked to a wide spectrum of human diseases....

  20. A Influência da Escola e da Mídia na Obtenção dos Conhecimentos Astronômicos

    Science.gov (United States)

    da Cunha, W. S.; Voelzke, M. R.; Amaral, L. H.

    2006-08-01

    O universo em que vivemos possui segredos jamais imaginados pelo homem, fruto da pequena proporção que ocupamos diante de um cosmos infinito. A astronomia funciona como um instrumento que sacia a sede humana em desvendar esses segredos, estudando as galáxias, quasares, pulsares além da existência de todos os elementos que preenchem o espaço cósmico, o vácuo, não mais vazio como se pensou em outros tempos. A mídia explora esse campo de forma mística e também científica. A difusão adequada e dentro dos padrões educacionais vigentes, de conceitos astronômicos, se faz necessária, devido sua presença nos conteúdos escolares, centros de ciência e na mídia, de modo geral. A reforma do Currículo Básico da Escola Pública da maioria dos Estados brasileiros introduziu conceitos astronômicos desde a pré-escola até o Ensino Médio. Num estudo realizado com 1.032 alunos do Ensino Médio de seis escolas estaduais, revelou-se através da aplicação de um questionário que abordava conheciment os básicos em astronomia, como estes foram adquiridos e qual era a infra-estrutura oferecida pela escola: para 66,2% dos entrevistados o professor já fez alguma apresentação a respeito de astronomia. O presente estudo revelou também que 44,5% dos alunos entrevistados adquiriram seus conhecimentos astronômicos na escola, 28,1% através da televisão e 27,4% afirmaram que seus conhecimentos foram obtidos através de outros tipos de mídia (internet, filmes e revistas). Embora o estudo revele claramente que há certo equilíbrio na forma em que os alunos obtiveram seus conhecimentos astronômicos, a mídia ainda explora e muitas vezes desperta o interesse pela astronomia com assuntos que não fazem parte de nosso cotidiano como, por exemplo, o homem na Lua, os projetos espaciais e a primeira viagem de um astronauta brasileiro no espaço. Porém, em certos casos, a mídia pode promover conhecimentos incompletos ou mesmo equivocados sobre os conceitos que envolvam

  1. Percepção Astronômica de Alunos do Ensino Médio da Rede Estadual de São Paulo

    Science.gov (United States)

    de Oliveira, E. F.; Voelzke, M. R.; Amaral, L. H.

    2005-08-01

    Embora a astronomia seja uma das ciências mais antigas da humanidade e muitos dos conceitos astronômicos serem populares, principalmente nesta época de alta globalização do conhecimento por intermédio de eficientes meios de comunicação e de obtenção da informação, notadamente através da internet, observa-se que uma parcela significativa dos estudantes encontra-se à margem dessas informações. O presente trabalho visa analisar o nível de conhecimento básico dos alunos de Ensino Médio da rede estadual da cidade de Suzano quanto aos fenômenos astronômicos que os rodeiam, tais como a sucessão dos dias e das estações do ano, além de questioná-los sobre fatos genéricos tais como: quais são os astros que se encontram mais próximos do planeta Terra, o que vem a ser o Sol, o Big Bang, um ano-luz, uma estrela cadente, a estrela de Bélem e o que ocasionou a extinção dos dinossauros. Para tanto foi elaborado um formulário constando de questões de múltipla escolha, o qual foi aplicado no primeiro colegial noturno da Escola Estadual Batista Renzi. Num espaço amostral de 34 alunos constatou-se que apenas 29,4% compreendiam a sucessão dos dias da semana, que apenas 20,6% explicaram corretamente as estações do ano, que apenas 20,6% tinham idéia de quais são os objetos celestes mais próximos da Terra, em contraposição 67,6% sabiam classificar corretamente o Sol como estrela, 55,9% relacionavam o Big Bang à origem do universo, apenas 20,6% identificavam um ano-luz como unidade de distância, 32,4% reconheciam uma estrela cadente como meteoro, 41,2% consideravam a estrela de Belém como um cometa e 50,0% explicaram corretamente a extinção dos dinossauros. A presente análise será expandida para as demais classes de primeiro colegial, não somente do período noturno, mas também do diurno da Escola Estadual Batista Renzi, bem como o formulário será devidamente ampliado. Já nesta primeira fase nota-se claramente o pequeno discernimento

  2. Cálcul estructural d'un Observatori Astronómic situat a La Palma (Canàries), segons Normativa ENV 1993-1-1

    OpenAIRE

    Lacroizette i Mañas, Xavier

    2004-01-01

    Premi al millor Projecte de Fi de Carrera presentat durant el curs 2004-2005 en l'àmbit de Construcció que atorga el GREMI DE CONSTRUCTORS D'OBRES El present Projecte de Fi de Carrera està dedicat al disseny i càlcul estructural d’un dels complexes que composen l’Observatori Astronòmic del "Roque de los Muchachos", situat a la illa de la Palma (Canàries). Els diferents càlculs de la estructura metàl·lica s’han realitzat segons la normativa experimental europea ENV 1993-1-1, més coneg...

  3. Supuestos y filiaciones filosóficas de los paradigmas astronómicos en el virreinato del Perú

    Directory of Open Access Journals (Sweden)

    Roberto Katayama Omura

    2014-03-01

    Full Text Available En el presente artículo se estudian los supuestos y filiaciones filosófico-naturales de los paradigmas astronómicos vigentes en el virreinato delPerú. Se busca demostrar que hasta el siglo XVIII fue dominante el paradigma clásico o geocéntrico en la versión moderna de Tycho Brahe y quetambién estuvo presente el paradigma clásico en su versión tradicionalo ptolemaica aunque con menos fuerza. Finalmente, se propone quedesde mediados del siglo XVIII se introduce en el virreinato peruano elparadigma moderno kepleriano-newtoniano el cual se impondrá a finesdel mismo siglo.

  4. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade...

  5. Satellite Communications

    CERN Document Server

    Pelton, Joseph N

    2012-01-01

    The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

  6. Satellite observations

    Science.gov (United States)

    1984-05-01

    In 1982 and 1983, six scientific satellites were operated successfully. Two of them, JIKIKEN and ISS-b, performed observations of the Earth's plasma environment. HINOTORI, the solar maximum satellite, observed a number of solar flares. HAKUCHO and newly launched TENMA conducted various observations of cosmic X-ray sources. HIMAWARI-2 is a meteorological satellite but its payload includes a solar particle monitor. EXOS-C was successfully launched in February, 1983, and participants in the MAP (Middle Atmosphere Program). Following these missions, the PLANET-A project comprising two missions, MS-T5 and PLANET-A, is under preparation for the participation in the international cooperative exploration of Comet P/Halley. The third X-ray astronomy satellite ASTRO-C is currently scheduled for 1987 launch.

  7. Some background about satellites

    Science.gov (United States)

    Burns, Joseph A.

    1986-01-01

    Four tables of planetary and satellite data are presented which list satellite discoveries, planetary parameters, satellite orbits, and satellite physical properties respectively. A scheme for classifying the satellites is provided and it is noted that most known moons fall into three general classes: regular satellites, collisional shards, and irregular satellites. Satellite processes are outlined with attention given to origins, dynamical and thermal evolution, surface processes, and composition and cratering. Background material is provided for each family of satellites.

  8. PSR B0329+54: Substructure in the scatter-broadened image discovered with RadioAstron on baselines of up to 235,000 km

    CERN Document Server

    Popov, M V; Bartel, N; Gwinn, C R; Johnson, M D; Joshi, B C; Kardashev, N S; Karuppusamy, R; Kovalev, Y Y; Kramer, M; Rudnitskii, A G; Safutdinov, E R; Shishov, V I; Smirnova, T V; Soglasnov, V A; Zensus, J A; Zhuravlev, V I

    2015-01-01

    We studied scattering properties of the pulsar PSR B0329+54 with a ground-space radio interferometer RadioAstron which included the 10-m Space Radio Telescope, the 110-m Green Bank Telescope, the 14x25-m Westerbork Synthesis Radio Telescope, and the 64-m Kalyazin Radio Telescope. The observations were performed at 324 MHz on baselines of up to 235,000 km in November 2012 and January 2014. At short ground-space baselines of less than about 20,000 km, the visibility amplitude decreases with the projected baseline length, providing a direct measurement of the diameter of the scattering disk of 4.7$\\pm$0.9 mas. The size of the diffraction spot near Earth is 15,000$\\pm$3,000 km. At longer baselines of up to 235,000 km, where no interferometric detection of the scattering disk would be expected, significant visibilities were observed with amplitudes scattered around a constant value. These detections result in a discovery of a substructure in the completely resolved scatter-broadened image of the pointlike source, ...

  9. RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

    CERN Document Server

    Lobanov, A P; Bruni, G; Kovalev, Y Y; Anderson, J; Bach, U; Kraus, A; Zensus, J A; Lisakov, M M; Sokolovsky, K V; Voytsik, P A

    2015-01-01

    Polarization of radio emission in extragalactic jets at a sub-milliarcsecond angular resolution holds important clues for understanding the structure of the magnetic field in the inner regions of the jets and in close vicinity of the supermassive black holes in the centers of active galaxies. Space VLBI observations provide a unique tool for polarimetric imaging at a sub-milliarcsecond angular resolution and studying the properties of magnetic field in active galactic nuclei on scales of less than 10^4 gravitational radii. A space VLBI observation of high-redshift quasar TXS 0642+449 (OH 471), made at a wavelength of 18 cm (frequency of 1.6 GHz) as part of the Early Science Programme (ESP) of the RadioAstron} mission, is used here to test the polarimetric performance of the orbiting Space Radio Telescope (SRT) employed by the mission, to establish a methodology for making full Stokes polarimetry with space VLBI at 1.6 GHz, and to study the polarized emission in the target object on sub-milliarcsecond scales. ...

  10. PSR B0329+54: Statistics of Substructure Discovered within the Scattering Disk on RadioAstron Baselines of up to 235,000 km

    Science.gov (United States)

    Gwinn, C. R.; Popov, M. V.; Bartel, N.; Andrianov, A. S.; Johnson, M. D.; Joshi, B. C.; Kardashev, N. S.; Karuppusamy, R.; Kovalev, Y. Y.; Kramer, M.; Rudnitskii, A. G.; Safutdinov, E. R.; Shishov, V. I.; Smirnova, T. V.; Soglasnov, V. A.; Steinmassl, S. F.; Zensus, J. A.; Zhuravlev, V. I.

    2016-05-01

    We discovered fine-scale structure within the scattering disk of PSR B0329+54 in observations with the RadioAstron ground–space radio interferometer. Here we describe this phenomenon, characterize it with averages and correlation functions, and interpret it as the result of decorrelation of the impulse-response function of interstellar scattering between the widely separated antennas. This instrument included the 10 m Space Radio Telescope, the 110 m Green Bank Telescope, the 14 × 25 m Westerbork Synthesis Radio Telescope, and the 64 m Kalyazin Radio Telescope. The observations were performed at 324 MHz on baselines of up to 235,000 km in 2012 November and 2014 January. In the delay domain, on long baselines the interferometric visibility consists of many discrete spikes within a limited range of delays. On short baselines it consists of a sharp spike surrounded by lower spikes. The average envelope of correlations of the visibility function shows two exponential scales, with characteristic delays of {τ }1=4.1+/- 0.3 μ {{s}} and {τ }2=23+/- 3 μ {{s}}, indicating the presence of two scales of scattering in the interstellar medium. These two scales are present in the pulse-broadening function. The longer scale contains 0.38 times the scattered power of the shorter one. We suggest that the longer tail arises from highly scattered paths, possibly from anisotropic scattering or from substructure at large angles.

  11. PSR B0329+54: Substructure in the scatter-broadened image discovered with RadioAstron on baselines up to 330,000 km

    CERN Document Server

    Popov, M V; Gwinn, C R; Johnson, M D; Andrianov, A; Fadeev, E; Joshi, B C; Kardashev, N S; Karuppusamy, R; Kovalev, Y Y; Kramer, M; Rudnitskiy, A; Shishov, V I; Smirnova, T V; Soglasnov, V A; Zensus, J A

    2016-01-01

    We have resolved the scatter-broadened image of PSR B0329+54 and detected substructure within it. These results are not influenced by any extended structure of a source but instead are directly attributed to the interstellar medium. We obtained these results at 324 MHz with the ground-space interferometer RadioAstron which included the space radio telescope (SRT), ground-based Westerbork Synthesis Radio Telescope and 64-m Kalyazin Radio Telescope on baseline projections up to 330,000 km in 2013 November 22 and 2014 January 1 to 2. At short 15,000 to 35,000 km ground-space baseline projections the visibility amplitude decreases with baseline length providing a direct measurement of the size of the scattering disk of 4.8$\\pm$0.8 mas. At longer baselines no visibility detections from the scattering disk would be expected. However, significant detections were obtained with visibility amplitudes of 3 to 5% of the maximum scattered around a mean and approximately constant up to 330,000 km. These visibilities reflec...

  12. Satellite description

    Science.gov (United States)

    Gillett, F. C.; Clegg, P. E.; Neugebauer, G.; Langford, D.; Pouw, A.; Irace, W.; Houck, J.

    The onboard computers and their associated software, the attitude control system, and data recording and the communication links of the infrared astronomy satellite (TRAS) are discussed. The IRAS telescope system is considered in detail. Attention is directed towards the cryogenics, thermal control, optics, focal plane assembly, and electronics associated with the telescope system.

  13. Satellite Heart

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The usefulness of China’s own global navigation system is being extended by technological breakthroughs China has successfully developed the country’s first navigation chip that is expected to be the heart of the country’s satellite-based navigation system,according to a report released on February 21. The Navigation I chip,developed by the Shanghai Fukong Hualong Micro-system

  14. Solar satellites

    Energy Technology Data Exchange (ETDEWEB)

    Poher, C.

    1982-01-01

    A reference system design, projected costs, and the functional concepts of a satellite solar power system (SSPS) for converting sunlight falling on solar panels of a satellite in GEO to a multi-GW beam which could be received by a rectenna on earth are outlined. Electricity transmission by microwaves has been demonstrated, and a reference design system for supplying 5 GW dc to earth was devised. The system will use either monocrystalline Si or concentrator GaAs solar cells for energy collection in GEO. Development is still needed to improve the lifespan of the cells. Currently, the cell performance degrades 50 percent in efficiency after 7-8 yr in space. Each SSPS satellite would weigh either 34,000 tons (Si) or 51,000 tons (GaAs), thereby requiring the fabrication of a heavy lift launch vehicle or a single-stage-to-orbit transport in order to minimize launch costs. Costs for the solar panels have been estimated at $500/kW using the GaAs technology, with transport costs for materials to GEO being $40/kg.

  15. Qual o Papel da Escola e da Mídia na Obtenção dos Conhecimentos Astronômicos?

    Science.gov (United States)

    da Cunha, W. S.; Voelzke, M. R.; Amaral, L. H.

    2007-08-01

    É amplamente reconhecido que as pessoas em geral têm grande fascínio e interesse pela Astronomia. Por outro lado, o conteúdo dessa área incluído no ensino formal está longe de ser abrangente e suficiente para suprir a demanda. Esse interesse permite aperfeiçoar a divulgação e o ensino não formal de Astronomia através da mídia aliando a adequação do conteúdo à expectativa das pessoas. A reforma do Currículo Básico da Escola Pública da maioria dos Estados brasileiros tem introduzido Astronomia desde a pré-escola até o Ensino Médio. Num estudo realizado com 1180 alunos do Ensino Médio de seis escolas estaduais, revelou-se através da aplicação de um formulário contendo questões que abordavam conhecimentos básicos em Astronomia, como foram adquiridos tais conhecimentos e à infra-estrutura da escola. Para 66,1% dos entrevistados o professor já fez alguma apresentação a respeito de Astronomia. O presente estudo revelou também que 54,4% dos alunos entrevistados adquiriram seus conhecimentos astronômicos na escola, 18,4% através da televisão e 27,1% afirmaram que seus conhecimentos foram obtidos através de outros tipos de mídia (internet, livros didáticos, filmes e revistas). Embora o estudo revele claramente que há certo equilíbrio no meio em que os alunos obtiveram seus conhecimentos astronômicos, a mídia busca não somente sua difusão, mas a disponibilização desse conhecimento de maneira correta, que às vezes, não é atingido, apresentando conceitos sem fundamentação e incorretos. Por outro lado, no dia-a-dia escolar, é comum encontrar professores que vêm para as aulas com concepções prévias, que podem diferir substancialmente das idéias a serem ensinadas, dificultando o aprendizado de futuros conceitos científicos. Uma avaliação criteriosa, avaliando as dificuldades dos professores em determinar o sentido correto dos conceitos e observando a metodologia que utilizam no ensino, poderá proporcionar uma melhor

  16. Mediciones de irradiancia solar y capa de ozono durante el eclipse de Sol de 1994 en el Observatorio Astronómico de Rosario, Argentina

    Science.gov (United States)

    Piacentini, R. D.; Micheletti, M. I.

    We show results of measurements made during the Sun's eclipse of November 3, 1994, in Observatorio Astronómico de Rosario (32o 57' S, 60o 37' W, 25 m a.s.l.). The eclipse begin at 8:41 local hour, reached its maximum with 77% of the surface covered at 9:51 and finished at 11:04. The direct solar irradiance of 300 nm and 313 nm were able to be measured, due to the fact that during the whole period the sky remained completed uncovered (zero percent cloudiness). The measurements were made with the portable ozonometer developed by Tocho and co-workers. They show the characterictic decrease due to the occultation of the source, which is approximately proportional to the surface's diminution. When crossing the earth's atmosphere to arrive to the observation point, these irradiances are affected mainly by the ozone layer, specially the irradiance at lower wavelength, what let it to determine by comparison the thickness of this layer. The total ozone thickness distributed between the troposphere and the stratosphere shows an oscillation, whose amplitude, since the occurence of the maximum of occulation, has a mean value of 4%, and whose period is of approximately 2100 seconds, being both numbers considerably larger than the ones registred by Mims III y Mims (Geophysical Research Letters, 20, 367, 1993) during the eclipse of July 11, 1991 and by Tocho, Da Silva y Rivas (XVIII Quadriennial Ozone Symposiom, Italy, September, 1996) during the same eclipse analyzed in the present work, but observed in Salta. As complementary results, we measured the global irradiance and the ambient temperature during this astronomical event.

  17. Mutual Events in the Uranian satellite system in 2007

    Science.gov (United States)

    Arlot, J. E.

    2008-09-01

    The equinox time on the giant planets When the Sun crosses the equatorial plane of a giant planet, it is the equinox time occurring every half orbit of the planet, i.e. every 6 years for Jupiter, 14 years for Saturn, 42 years for Uranus and 82 years for Neptune. Except Neptune, each planet have several major satellites orbiting in the equatorial plane, then, during the equinox time, the satellites will eclipse each other mutually. Since the Earth follows the Sun, during the equinox time, a terrestrial observer will see each satellite occulting each other during the same period. These events may be observed with photometric receivers since the light from the satellites will decrease during the events. The light curve will provide information on the geometric configuration of the the satellites at the time of the event with an accuracy of a few kilometers, not depending on the distance of the satellite system. Then, we are able to get an astrometric observation with an accuracy several times better than using direct imaging for positions. Equinox on Uranus in 2007 In 2007, it was equinox time on Uranus. The Sun crossed the equatorial plane of Uranus on December 6, 2007. Since the opposition Uranus-Sun was at the end of August 2007, observations were performed from May to December 2007. Since the declination of Uranus was between -5 and -6 degrees, observations were better to make in the southern hemisphere. However, some difficulties had to be solved: the faintness of the satellites (magnitude between 14 and 16), the brightness of the planet (magnitude 5) making difficult the photometric observation of the satellites. The used of K' filter associated to a large telescope allows to increase the number of observable events. Dynamics of the Uranian satellites One of the goals of the observations was to evaluate the accuracy of the current dynamical models of the motion of the satellites. This knowledge is important for several reasons: most of time the Uranian system is

  18. A Reappraising of Cosmography: the Interface Between Astronomical and Geographic Studies. (Breton Title: Releitura do Conceito de Cosmografia: a Interface Entre os Estudos Astronômicos e Geográficos.) Una Relectura del Concepto de Cosmografía: la Interfase Entre los Estudios Astronómicos y Geográficos

    Science.gov (United States)

    Azevedo Sobreira, Paulo Henrique

    2012-12-01

    The concept of "Cosmography" is in disuse since the 80s of the last century, but the astronomical themes previously discussed in the school subjects of Geography and Cosmography remain in current textbooks. The use of term "Cosmography" was rescued in this research, and the study of its re-signification prompted the appearance of the term Geographic Cosmography. The Geographic Cosmography is a field of studies of the Geography, whose set of knowledge and skills is predominantly scholar. It studies the interface between terrestrial and celestial knowledge, and assigns a geographic significance to them. It examines human and natural relationships with Sidereal Space and its consequences for society and nature. O conceito de "Cosmografia" está em desuso desde os anos 80 do século XX, mas os temas astronômicos anteriormente abordados nas disciplinas escolares de Cosmografia e de Geografia permanecem nos atuais livros didáticos. O uso do termo "Cosmografia" foi resgatado nesta pesquisa e o estudo de sua ressignificação proporcionou o surgimento do termo Cosmografia Geográfica. A Cosmografia Geográfica é um campo de estudos da Geografia, cujo conjunto de conhecimentos e habilidades é predominantemente escolar. Estuda a interface entre os conhecimentos terrestres e os celestes e lhes atribui significância geográfica. Analisa as relações humanas e naturais com o Espaço Sideral e suas consequências para a sociedade e a natureza. Aunque el concepto de "Cosmografía" no se usa desde la década de los '80 del siglo pasado, los temas astronómicos que se enseñaban anteriormente en las asignaturas escolares de Cosmografía y de Geografía permanecen en los actuales libros didácticos. El uso del término "Cosmografía" fue rescatado en esta investigación y el estudio de su resignificación proporcionó el surgimiento del término Cosmografía Geográfica. La Cosmografía Geográfica es un campo de estudio de la Geografía, donde el conjunto de conocimientos y

  19. Novas tecnoloxías e ensinanza da Astronomía: explorando o Sistema Solar e simulando fenómenos astronómicos sinxelos en 1º de ESO

    OpenAIRE

    María Álvarez Lires; Irene Pérez Rodríguez; Uxío Pérez Rodríguez

    2009-01-01

    El currículo del Primer Curso de ESO incluye como contenidos obligatorios aspectos relacionados con los temas astronómicos entre los que se cuentan la identificación de los elementos del Sistema Solar, la interpretación de los fenómenos relacionados con los movimientos de la Tierra y el uso de técnicas sencillas de orientación basadas en la observación de los astros. En este artículo se propone emplear una aplicación informática gratuita, Stellarium, cuando se aborden estos temas en el aula. ...

  20. Internetworking with satellite constellations

    OpenAIRE

    Wood, L.

    2001-01-01

    Here, we examine networking and internetworking issues affecting satellite networking in complex satellite constellation networks, and determine what is needed in order to support services based on the TCP/IP suite well in satellite constellations.

  1. Geostationary Satellite (GOES) Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from radiometer instruments on SMS (ATS) and GOES satellites in geostationary orbit. These satellites produced...

  2. The Meanings of Astronomical Observation: An Analysis on the Basis of Relationship with Knowledge. (Spanish Title: Los Sentidos de la Observación Astronómica: un Análisis sobre la Base de la Relación con el Saber.) Os Sentidos da Observação Astronômica: Uma Análise com Base na Relação com o Saber

    Science.gov (United States)

    Klein, Alberto Eduardo; de Mello Arruda, Sergio; Meneghello Passos, Marinez; Vinicius Domenes Zapparoli, Ferdinando

    2010-12-01

    This article presents results of a research which aimed to understand the meanings that people construct for astronomical observation. The subjects, students and school teachers, initially received some instruction on how to view astronomical objects through the telescope. After the observation was realized, they were interviewed. The data analysis allowed the creation of 12 categories, later interpreted on the basis of relationship with knowledge (relation to the world, with himself and with others), as presented by Bernard Charlot. Este artículo presenta los resultados de una investigación que tuvo como objetivo comprender los sentidos que las personas construyen para la observación astronómica. Los sujetos, los estudiantes y maestros de escuela, recibieron inicialmente algunas instrucciones sobre cómo ver los objetos astronómicos a través del telescopio. Al término de la observación, fueron entrevistados. El análisis de datos permitió la creación de 12 categorías que más tarde fueron interpretadas sobre la base de la relación con el conocimiento (relación con el mundo, consigo mismo y con los demás), tal como presentado por Bernard Charlot. Este artigo apresenta resultados de uma pesquisa que objetivou entender quais os sentidos que as pessoas constroem para a observação astronômica. Os sujeitos da pesquisa, estudantes e professores do ensino médio, receberam inicialmente alguma instrução sobre como visualizar os objetos astronômicos através do telescópio. Após a realização da observação, eles foram entrevistados. A análise dos dados permitiu a elaboração de 12 categorias que foram posteriormente interpretadas com base nas relações com o saber (relação com o mundo, consigo mesmo e com o outro), conforme apresentadas por Bernard Charlot.

  3. Iodine Satellite

    Science.gov (United States)

    Kamhawi, Hani; Dankanich, John; Martinez, Andres; Petro, Andrew

    2015-01-01

    The Iodine Satellite (iSat) spacecraft will be the first CubeSat to demonstrate high change in velocity from a primary propulsion system by using Hall thruster technology and iodine as a propellant. The mission will demonstrate CubeSat maneuverability, including plane change, altitude change and change in its closest approach to Earth to ensure atmospheric reentry in less than 90 days. The mission is planned for launch in fall 2017. Hall thruster technology is a type of electric propulsion. Electric propulsion uses electricity, typically from solar panels, to accelerate the propellant. Electric propulsion can accelerate propellant to 10 times higher velocities than traditional chemical propulsion systems, which significantly increases fuel efficiency. To enable the success of the propulsion subsystem, iSat will also demonstrate power management and thermal control capabilities well beyond the current state-of-the-art for spacecraft of its size. This technology is a viable primary propulsion system that can be used on small satellites ranging from about 22 pounds (10 kilograms) to more than 1,000 pounds (450 kilograms). iSat's fuel efficiency is ten times greater and its propulsion per volume is 100 times greater than current cold-gas systems and three times better than the same system operating on xenon. iSat's iodine propulsion system consists of a 200 watt (W) Hall thruster, a cathode, a tank to store solid iodine, a power processing unit (PPU) and the feed system to supply the iodine. This propulsion system is based on a 200 W Hall thruster developed by Busek Co. Inc., which was previously flown using xenon as the propellant. Several improvements have been made to the original system to include a compact PPU, targeting greater than 80 percent reduction in mass and volume of conventional PPU designs. The cathode technology is planned to enable heaterless cathode conditioning, significantly increasing total system efficiency. The feed system has been designed to

  4. Astronomical Perception of the Secondary School's Students in São Paulo's State School in Suzano City. (Spanish Title: Percepción Astronómica de Alumnos de la Enseñanza Media de la Red Estatal de San Pablo en la Ciudad de Suzano.) Percepção Astronômica de um Grupo de Alunos do Ensino Médio da Rede Estadual de São Paulo da Cidade de Suzano

    Science.gov (United States)

    França de Oliveira, Edilene; Voelzke, Marcos Rincon; Amaral, Luis Henrique

    2007-12-01

    Although Astronomy is one of the oldest Sciences in the world and many of its concepts are popular, it is possible to observe that a major part of the students do not know about them. This work aims to analyse the basic knowledge of the secondary school's students of a state school in the city of Suzano, related to the astronomical phenomena, which surround them. It was carried out a questionnaire of multiple choice to 34 students from the first grade, night classes, of the state school Batista Renzi. From the sample, 34 students, only 29.4% of them could understand the succession of the days; 20.6% could explain the seasons of the year and 20.6% had some idea about celestial objects nearer to the Earth. In turn, 67.6% correctly classified the Sun as a star; 55.9% related the Big Bang to the origin of Universe; only 20.6% identified the light-year as an unit of distance and 32.4% recognized a falling star as a meteor. The actual analysis was expanded to more 310 students of other classes, grades and periods of the same school. In this first stage, it can be noted the students' little discernment of the astronomical events and mainly the great confusion about the appropriate meaning of popular astronomical terms. Aunque la Astronomía es una de las ciencias más antiguas de la humanidad y muchos de los conceptos astronómicos son populares, se observa que una parcela significativa de los estudiantes se encuentra al margen de estas informaciones. El presente trabajo pretende analizar el nivel de conocimiento básico de los alumnos de la Enseñanza Media de la Red Estatal de la ciudad de Suzano con relación a los fenómenos astronómicos que los rodean. Con este objetivo fue elaborado un formulario constando de preguntas de selección múltipla, aplicado en el primer año nocturno de la Escuela Estatal Batista Renzi. En un universo de 34 alumnos se constató que solamente 29,4% comprendían la sucesión de los días; 20,6% explicaron correctamente las estaciones del

  5. Influencia de la marea astronómica sobre las variaciones del nivel del Río Negro en la zona de Carmen de Patagones

    Directory of Open Access Journals (Sweden)

    Enrique D'Onofrio

    2010-12-01

    Full Text Available El Río Negro, límite natural entre las provincias de Buenos Aires y Río Negro, es uno de los ríos más importantes de la Patagonia que desemboca en el Océano Atlántico. Es navegable desde su desembocadura hasta Carmen de Patagones por embarcaciones de hasta 2,04 m de calado, dificultándose por irregularidades en la profundidad aguas arriba. La onda de marea proveniente del océano Atlántico ingresa al río haciendo que este adopte un régimen semidiurno hasta Carmen de Patagones. El conocimiento de la onda de marea en este tramo del río es de fundamental importancia para la calibración de modelos numéricos, el perfeccionamiento de los sistemas de alerta de inundaciones y la toma de decisiones relacionadas con el manejo costero. En este trabajo se analizan cuatro series de mediciones de marea, dos obtenidas en el hidrómetro de Carmen de Patagones con una duración de 608 y 731 días, una de 77 días proveniente de un mareómetro instalado en el kilómetro 18 del río y una de 79 días obtenida con un sensor de presión fondeado en proximidades de Punta Redonda (desembocadura del Río Negro. Se calculan y comparan los espectros de potencia de las alturas observadas en los tres sitios para detectar los cambios energéticos producidos en la banda de frecuencias correspondientes a la marea astronómica. De su comparación surge que la energía de las componentes semidiurnas y diurnas disminuye un 22% y un 45% respectivamente desde la desembocadura del Río Negro hasta Carmen de Patagones. En contraposición se observa un ligero aumento de la energía correspondiente a las frecuencias de las componentes cuarto diurnas. Esto se debe fundamentalmente a procesos no lineales inducidos por aguas someras y a irregularidades en la morfología del fondo del río. Para obtener las amplitudes y épocas de la marea se realizan análisis armónicos por el método de cuadrados mínimos. Las amplitudes de las componentes diurnas en Carmen de Patagones

  6. Asteroid Satellites

    Science.gov (United States)

    Merline, W. J.

    2001-11-01

    Discovery and study of small satellites of asteroids or double asteroids can yield valuable information about the intrinsic properties of asteroids themselves and about their history and evolution. Determination of the orbits of these moons can provide precise masses of the primaries, and hence reliable estimates of the fundamental property of bulk density. This reveals much about the composition and structure of the primary and will allow us to make comparisons between, for example, asteroid taxonomic type and our inventory of meteorites. The nature and prevalence of these systems will also give clues as to the collisional environment in which they formed, and have further implications for the role of collisions in shaping our solar system. A decade ago, binary asteroids were more of a theoretical curiosity. In 1993, the Galileo spacecraft allowed the first undeniable detection of an asteroid moon, with the discovery of Dactyl, a small moon of Ida. Since that time, and particularly in the last year, the number of known binaries has risen dramatically. Previously odd-shaped and lobate near-Earth asteroids, observed by radar, have given way to signatures indicating, almost certainly, that at least four NEAs are binary systems. The tell-tale lightcurves of several other NEAs reveal a high likelihood of being double. Indications are that among the NEAs, there may be a binary frequency of several tens of percent. Among the main-belt asteroids, we now know of 6 confirmed binary systems, although their overall frequency is likely to be low, perhaps a few percent. The detections have largely come about because of significant advances in adaptive optics systems on large telescopes, which can now reduce the blurring of the Earth's atmosphere to compete with the spatial resolution of space-based imaging (which itself, via HST, is now contributing valuable observations). Most of these binary systems have similarities, but there are important exceptions. Searches among other

  7. Satellite data compression

    CERN Document Server

    Huang, Bormin

    2011-01-01

    Satellite Data Compression covers recent progress in compression techniques for multispectral, hyperspectral and ultra spectral data. A survey of recent advances in the fields of satellite communications, remote sensing and geographical information systems is included. Satellite Data Compression, contributed by leaders in this field, is the first book available on satellite data compression. It covers onboard compression methodology and hardware developments in several space agencies. Case studies are presented on recent advances in satellite data compression techniques via various prediction-

  8. Trends in communications satellites

    CERN Document Server

    Curtin, Denis J

    1979-01-01

    Trends in Communications Satellites offers a comprehensive look at trends and advances in satellite communications, including experimental ones such as NASA satellites and those jointly developed by France and Germany. The economic aspects of communications satellites are also examined. This book consists of 16 chapters and begins with a discussion on the fundamentals of electrical communications and their application to space communications, including spacecraft, earth stations, and orbit and wavelength utilization. The next section demonstrates how successful commercial satellite communicati

  9. Xichang Satellite Launch Center

    Institute of Scientific and Technical Information of China (English)

    LiuJie

    2004-01-01

    Xichang Satellite Launch Center(XSLC) is mainly for geosynchronous orbit launches. The main purpose of XSLC is to launch spacecraft, such as broadcasting,communications and meteorological satellites, into geo-stationary orbit.Most of the commercial satellite launches of Long March vehicles have been from Xichang Satellite Launch Center. With 20 years' development,XSLC can launch 5 kinds of launch vehicles and send satellites into geostationary orbit and polar orbit. In the future, moon exploration satellites will also be launched from XSLC.

  10. China's satellite communications discussed

    Science.gov (United States)

    Ruhou, Z.

    1986-04-01

    In 1972, China began to enter the age of satellite comunications, and it was realized that satellites could play a large role in television transmission in China. The experimental broadcasting of satellite television programs was begun in 1978, and satisfactory results were obtained. The success of the television transmission demonstration has led to important decisions regarding development of a domestic satellite communications system. Before specialized communications satellites are launched, the decision was made to lease an international communications satellite transmitter. The responsibility of the ground stations were discussed.

  11. Novas tecnoloxías e ensinanza da Astronomía: explorando o Sistema Solar e simulando fenómenos astronómicos sinxelos en 1º de ESO

    Directory of Open Access Journals (Sweden)

    María Álvarez Lires

    2009-11-01

    Full Text Available El currículo del Primer Curso de ESO incluye como contenidos obligatorios aspectos relacionados con los temas astronómicos entre los que se cuentan la identificación de los elementos del Sistema Solar, la interpretación de los fenómenos relacionados con los movimientos de la Tierra y el uso de técnicas sencillas de orientación basadas en la observación de los astros. En este artículo se propone emplear una aplicación informática gratuita, Stellarium, cuando se aborden estos temas en el aula. Se describirán algunas de las posibilidades que tiene este programa de planetario y se proporcionarán ejemplos concretos de actividades que pueden realizarse con su ayuda.

  12. Galileo satellite antenna modeling

    Science.gov (United States)

    Steigenberger, Peter; Dach, Rolf; Prange, Lars; Montenbruck, Oliver

    2015-04-01

    The space segment of the European satellite navigation system Galileo currently consists of six satellites. Four of them belong to the first generation of In-Orbit Validation (IOV) satellites whereas the other two are Full Operational Capability (FOC) satellites. High-precision geodetic applications require detailed knowledge about the actual phase center of the satellite and receiver antenna. The deviation of this actual phase center from a well-defined reference point is described by phase center offsets (PCOs) and phase center variations (PCVs). Unfortunately, no public information is available about the Galileo satellite antenna PCOs and PCVs, neither for the IOV, nor the FOC satellites. Therefore, conventional values for the IOV satellite antenna PCOs have been adopted for the Multi-GNSS experiment (MGEX) of the International GNSS Service (IGS). The effect of the PCVs is currently neglected and no PCOs for the FOC satellites are available yet. To overcome this deficiency in GNSS observation modeling, satellite antenna PCOs and PCVs are estimated for the Galileo IOV satellites based on global GNSS tracking data of the MGEX network and additional stations of the legacy IGS network. Two completely independent solutions are computed with the Bernese and Napeos software packages. The PCO and PCV values of the individual satellites are analyzed and the availability of two different solutions allows for an accuracy assessment. The FOC satellites are built by a different manufacturer and are also equipped with another type of antenna panel compared to the IOV satellites. Signal transmission of the first FOC satellite has started in December 2014 and activation of the second satellite is expected for early 2015. Based on the available observations PCO estimates and, optionally PCVs of the FOC satellites will be presented as well. Finally, the impact of the new antenna model on the precision and accuracy of the Galileo orbit determination is analyzed.

  13. GPS Satellite Simulation Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The GPS satellite simulation facility consists of a GPS satellite simulator controlled by either a Silicon Graphics Origin 2000 or PC depending upon unit under test...

  14. China's Recoverable Satellites

    Institute of Scientific and Technical Information of China (English)

    Tang Boehang

    2008-01-01

    @@ By the end of 2006, China had launched 24 recoverable satellites (FSW) in total. Among them, 23 were launched successfully, of which all but one were successfully recovered. Recoverable satellites launched by China are listed in Table 1.

  15. Satellite broadcasting in Europe

    Science.gov (United States)

    Bartholome, P.

    1984-05-01

    Three main communications services are recognized by the International Telecommunications Union: the Fixed Service, the Mobile Service and the Broadcasting Service. In Europe, EUTELSAT has just begun to exploit the first ECS satellite. The ESA-launched satellite was originally designed to provide an international public telecommunication service, however, the satellite will be used now almost exclusively for TV program distribution, while a second ECS satellite will be used for telephony. Despite plans for the launch of a third, countries in Europe are looking to other organizations such as INTELSAT for greater satellite capacity. Other organizations include Unisat, DFS/Copernicus, GDL, and Videosat. Both satellite and cable networks will increase the program-viewing audience, thus encouraging plans for a pan-European television service intended for an international audience. Although the combination of cable networks and distribution satellites looks promising, high-power broadcasting satellites will play an important role because of flexibility and additional program distribution.

  16. Satellite Tags- Hawaii EEZ

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Satellite tagging was implemented in 2013. Satellite tagging is conducted using a Dan Inject air rifle and deployment arrows designed by Wildlife Computers. Two...

  17. Satellite communication engineering

    CERN Document Server

    Kolawole, Michael Olorunfunmi

    2013-01-01

    An undeniably rich and thorough guide to satellite communication engineering, Satellite Communication Engineering, Second Edition presents the fundamentals of information communications systems in a simple and succinct way. This book considers both the engineering aspects of satellite systems as well as the practical issues in the broad field of information transmission. Implementing concepts developed on an intuitive, physical basis and utilizing a combination of applications and performance curves, this book starts off with a progressive foundation in satellite technology, and then moves on

  18. Theory of geostationary satellites

    CERN Document Server

    Zee, Chong-Hung

    1989-01-01

    Geostationary or equatorial synchronous satellites are a daily reminder of our space efforts during the past two decades. The nightly television satellite weather picture, the intercontinental telecommunications of television transmissions and telephone conversations, and the establishrnent of educational programs in remote regions on Earth are constant reminders of the presence of these satellites. As used here, the term 'geo­ stationary' must be taken loosely because, in the long run, the satellites will not remain 'stationary' with respect to an Earth-fixed reference frame. This results from the fact that these satellites, as is true for all satellites, are incessantly subject to perturbations other than the central-body attraction of the Earth. Among the more predominant pertur­ bations are: the ellipticity of the Earth's equator, the Sun and Moon, and solar radiation pressure. Higher harmonics of the Earth's potential and tidal effects also influence satellite motion, but they are of second­ order whe...

  19. Meteorological satellite systems

    CERN Document Server

    Tan, Su-Yin

    2014-01-01

    “Meteorological Satellite Systems” is a primer on weather satellites and their Earth applications. This book reviews historic developments and recent technological advancements in GEO and polar orbiting meteorological satellites. It explores the evolution of these remote sensing technologies and their capabilities to monitor short- and long-term changes in weather patterns in response to climate change. Satellites developed by various countries, such as U.S. meteorological satellites, EUMETSAT, and Russian, Chinese, Japanese and Indian satellite platforms are reviewed. This book also discusses international efforts to coordinate meteorological remote sensing data collection and sharing. This title provides a ready and quick reference for information about meteorological satellites. It serves as a useful tool for a broad audience that includes students, academics, private consultants, engineers, scientists, and teachers.

  20. Communication satellite applications

    Science.gov (United States)

    Pelton, Joseph N.

    The status and future of the technologies, numbers and services provided by communications satellites worldwide are explored. The evolution of Intelsat satellites and the associated earth terminals toward high-rate all-digital telephony, data, facsimile, videophone, videoconferencing and DBS capabilities are described. The capabilities, services and usage of the Intersputnik, Eutelsat, Arabsat and Palapa systems are also outlined. Domestic satellite communications by means of the Molniya, ANIK, Olympus, Intelsat and Palapa spacecraft are outlined, noting the fast growth of the market and the growing number of different satellite manufacturers. The technical, economic and service definition issues surrounding DBS systems are discussed, along with presently operating and planned maritime and aeronautical communications and positioning systems. Features of search and rescue and tracking, data, and relay satellite systems are summarized, and services offered or which will be offered by every existing or planned communication satellite worldwide are tabulated.

  1. GPS Satellites Orbits: Resonance

    Directory of Open Access Journals (Sweden)

    Luiz Danilo Damasceno Ferreira

    2009-01-01

    Full Text Available The effects of perturbations due to resonant geopotential harmonics on the semimajor axis of GPS satellites are analyzed. For some GPS satellites, secular perturbations of about 4 m/day can be obtained by numerical integration of the Lagrange planetary equations considering in the disturbing potential the main secular resonant coefficients. Amplitudes for long-period terms due to resonant coefficients are also exhibited for some hypothetical satellites orbiting in the neighborhood of the GPS satellites orbits. The results are important to perform orbital maneuvers of GPS satellites such that they stay in their nominal orbits. Also, for the GPS satellites that are not active, the long-period effects due to the resonance must be taken into account in the surveillance of the orbital evolutions of such debris.

  2. Satellite communication engineering

    CERN Document Server

    Kolawole, Michael Olorunfunmi

    2002-01-01

    Highlighting satellite and earth station design, links and communication systems, error detection and correction, and regulations and procedures for system modeling, integrations, testing, and evaluation, Satellite Communication Engineering provides a simple and concise overview of the fundamental principles common to information communications. It discusses block and feedback ciphering; covers orbital errors; evaluates multi-beam satellite networks; illustrates bus, electrical, and mechanical systems design; analyzes system reliability and availability; elucidates reflector/lens, phased array

  3. Methods of satellite oceanography

    Science.gov (United States)

    Stewart, R. H.

    1985-01-01

    The theoretical basis for remote sensing measurements of climate and ocean dynamics is examined. Consideration is given to: the absorption of electromagnetic radiation in the atmosphere; scattering in the atmosphere; and satellite observations using visible light. Consideration is also given to: the theory of radio scatter from the sea; scatter of centimeter waves from the sea; and the theory of operation of synthetic aperture radars. Additional topics include: the coordinate systems of satellite orbits for oceanographic remote sensing applications; the operating features of the major U.S. satellite systems for viewing the ocean; and satellite altimetry.

  4. Artificial earth satellites

    Directory of Open Access Journals (Sweden)

    V. R. Thiruvenkatachar

    1958-10-01

    Full Text Available A general discussion is given of the scientific and technological problems involved in the launching of earth satellites, covering various aspects such as the dynamical relationships involved, the propulsion and guidance systems, tracking and data transmission etc. The possible uses of satellites for scientific research as well as some of the likely future developments are also briefly indicated.

  5. Satellite communication systems

    CERN Document Server

    Evans, BG

    1999-01-01

    The book is very clear and comprehensive. The scope of the book is very large: almost all aspects of current satellite communication systems are studied. Hence, the book keeps its promise in that it provides a quick start for someone who is new to the satellite communications business.

  6. Communications technology satellite

    Science.gov (United States)

    1976-01-01

    A description of the Communications Technology Satellite (CTS), its planned orbit, its experiments, and associated ground facilities was given. The communication experiments, to be carried out by a variety of groups in both the United States and Canada, include tele-education, tele-medicine, community interaction, data communications and broadcasting. A historical summary of communications satellite development was also included.

  7. Beginnings of Satellite Navigation

    Directory of Open Access Journals (Sweden)

    Miljenko Solarić

    2008-05-01

    Full Text Available The first satellite navigation system called the Navy Navigation Satellite System (NNSS or TRANSIT was planned in the USA in 1958. It consisted of 5-6 artificial Earth satellites, was set in motion for the USA military in 1964, and in 1967 for civilian purposes. The frequency shift of received radio waves emitted from the satellite and caused by the Doppler effect was measured. The TRANSIT satellite speed of approaching or moving away was derived from that; the TRANSIT satellites emmited also their own coordinates. Then the ship's position was determined by an intersection of three hyperboloids, which were determined from differences of distances in three time intervals. Maintenance of this navigation system was stopped in 1996, but it is still being used in the USA Navy for exploring the ionosphere. Furthermore, results of Doppler measurements in international projects at the Hvar Observatory from 1982 and 1983. This was the first time in Croatia and the former country that the coordinates of the Hvar Observatory were determined in the unique world coordinate system WGS'72. The paper ends with a brief representation of the Tsiklon Doppler navigation system produced in the former Soviet Union, and there is a list of some of numerous produced and designed satellite navigation systems.Ključne riječi

  8. Overview of commercial satellite communications

    Science.gov (United States)

    Beakley, G. W.

    1984-07-01

    A brief history of communications satellites is presented, taking into account the launching of Sputnik 1 in October 1957, the Explorer 1 in January of 1958, the launch of the Score as the world's first active communications satellite in December 1958, the Communications Satellite Act in 1962, and the launch of 'Early Bird' in 1964. The Intelsat satellites are considered along with maritime satellite communications, the U.S. domestic satellite systems, Alaskan satellite communications, cable television, broadcast TV stations, print media, the hotel/motel industry as a large market for satellite communications terminals, the opening of a minicable and satellite master antenna TV market for TV receive-only systems, and business telecommunications earth terminals. Attention is also given to future directions regarding satellite positions, the concept of 'video-plus', and direct broadcast satellites.

  9. Handbook of satellite applications

    CERN Document Server

    Madry, Scott; Camacho-Lara, Sergio

    2013-01-01

    Top space experts from around the world have collaborated to produce this comprehensive, authoritative, and clearly illustrated reference guide to the fast growing, multi-billion dollar field of satellite applications and space communications. This handbook, done under the auspices of the International Space University based in France, addresses not only system technologies but also examines market dynamics, technical standards and regulatory constraints. The handbook is a completely multi-disciplinary reference book that covers, in an in-depth fashion, the fields of satellite telecommunications, Earth observation, remote sensing, satellite navigation, geographical information systems, and geosynchronous meteorological systems. It covers current practices and designs as well as advanced concepts and future systems. It provides a comparative analysis of the common technologies and design elements for satellite application bus structures, thermal controls, power systems, stabilization techniques, telemetry, com...

  10. Biological satellite Kosmos-936

    Science.gov (United States)

    Vedeshin, L. A.

    1978-01-01

    A description is given of physiological experiments performed on the biological satellite Kosmos-936. Other experiments to determine the electrostatic and dielectric responses to the effects of cosmic radiation are discussed.

  11. Small Satellite Transporter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The primary objective is to determine whether this small satellite transporter is capable of transporting at least four 6U CubeSats is possible for a given set of...

  12. Epos TCS Satellite Data

    Science.gov (United States)

    Manunta, Michele; Mandea, Mioara; Fernández-Turiel, José Luis; Stramondo, Salvatore; Wright, Tim; Walter, Thomas; Bally, Philippe; Casu, Francesco; Zeni, Giovanni; Buonanno, Sabatino; Zinno, Ivana; Tizzani, Pietro; Castaldo, Raffaele; Ostanciaux, Emilie; Diament, Michel; Hooper, Andy; Maccaferri, Francesco; Lanari, Riccardo

    2016-04-01

    TCS Satellite Data is devoted to provide Earth Observation (EO) services, transversal with respect to the large EPOS community, suitable to be used in several application scenarios. In particular, the main goal is to contribute with mature services that have already well demonstrated their effectiveness and relevance in investigating the physical processes controlling earthquakes, volcanic eruptions and unrest episodes as well as those driving tectonics and Earth surface dynamics. The TCS Satellite Data will provide two kinds of services: satellite products/services, and Value-added satellite products/services. The satellite products/services are composed of three (EPOSAR, GDM and COMET) well-identified and partly already operational elements for delivering Level 1 products. Such services will be devoted to the generation of SAR interferograms, DTM and ground displacement maps through the exploitation of different advanced EO techniques for InSAR and optical data analysis. The Value-added satellite products/services are composed of 4 elements (EPOSAR, 3D-Def, Mod and COMET) of Level 2 and 3 products. Such services integrate satellite and in situ measurements and observations to retrieve information on source mechanism, such as the geometry (spatial location, depth, volume changes) and the physical parameters of the deformation sources, through the exploitation of modelling approaches. The TCS Satellite Data will provide products in two different processing and delivery modes: 1- surveillance mode - routinely product generation; 2- on demand mode - product generation performed on demand by the user. Concerning the surveillance mode, the goal is providing continuous satellite measurements in areas of particular interest from a geophysical perspective (supersites). The objective is the detection of displacement patterns changing along time and their geophysical explanation. This is a valid approach for inter-seismic movements and volcanic unrest, post-seismic and post

  13. ASTRID II satellit projekt

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Primdahl, Fritz

    1997-01-01

    The report describes the instruments developed for the Swedish micro satellite "ASTRID II". Specifications of the two instruments realized under this contract, a Stellar Compass and a CSC magnetometer are given follwed by a description of the project status and plan.......The report describes the instruments developed for the Swedish micro satellite "ASTRID II". Specifications of the two instruments realized under this contract, a Stellar Compass and a CSC magnetometer are given follwed by a description of the project status and plan....

  14. CHINA LAUNCHES NEW SCIENTIFIC SATELLITE

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    China on Sept. 27, 2004 launched a scientific satellite atop a Long March 2D carrier rocket from Jiuquan Satellite Launch Center in Gansu province. 10 minutes after the launch, the satellite entered a preset orbit and is running sound at the orbit. It is the 20th recoverable satellite for scientific and technological

  15. China's Meteorological Satellite Application System

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen

    2008-01-01

    @@ China's meteorological satellite program consists of five systems,namely the satellite system,the launch vehicle system,the launch center system,TT&C and the ground application system.The satellite system consists of FengYun (FY) polar orbiting series and FY geostationary series,which are launched by LM launch vehicles from Taiyan Satellite Launch Center (TSLC) and Xichang Satellite Launch Center (XSLC) respectively.

  16. Satellite Imaging System

    Directory of Open Access Journals (Sweden)

    AA Somaie

    2013-06-01

    Full Text Available The aim of this paper is to present the essential elements of the electro-optical imaging system EOIS for space applications and how these elements can affect its function. After designing a spacecraft for low orbiting missions during day time, the design of an electro-imaging system becomes an important part in the satellite because the satellite will be able to take images of the regions of interest. An example of an electro-optical satellite imaging system will be presented through this paper where some restrictions have to be considered during the design process. Based on the optics principals and ray tracing techniques the dimensions of lenses and CCD (Charge Coupled Device detector are changed matching the physical satellite requirements. However, many experiments were done in the physics lab to prove that the resizing of the electro optical elements of the imaging system does not affect the imaging mission configuration. The procedures used to measure the field of view and ground resolution will be discussed through this work. Examples of satellite images will be illustrated to show the ground resolution effects.

  17. Small satellites - An overview

    Science.gov (United States)

    Ward, A. K.

    The present review of small satellites examines spacecraft activities in the U.K. and compiles a checklist of advantages and applications for the class. These advantages are illustrated with references to recent small satellite missions and technologies developed to facilitate such launches and projects. Specific programs examined include AMPTE-UKS, Viking, and the UoSAT program, and information is given regarding the Small Explorer program, the RAE Space Technology Research Vehicle, the AEA Argos Program, and space research programs in both Japan and India. Low-cost launches are shown to be available in the form of the Ariane Structure for Auxiliary Payloads, the Pegasus and Delta vehicles, and with the Shuttle Free-flying Getaway Special. Small-satellite technologies that play key roles in their effective implementation are: structure/thermal advances, attitude control systems, on-board communications, and power and data-handling systems.

  18. Solar Power Satellites

    CERN Document Server

    Flournoy, Don M

    2012-01-01

    Communication satellites are a $144 billion industry. Is there any space-based industry that could possibly beat that market? 'Solar Power Satellites' shows why and how the space satellite industry will soon begin expanding its market from relaying signals to Earth to generating energy in space and delivering it to the ground as electricity. In all industrialized nations, energy demand is growing exponentially. In the developing world, the need for energy is as basic as food and water. The Sun's energy is available everywhere, and it is non-polluting. As business plans demonstrate its technical feasibility, commercial potential, and environmental acceptability, every country on Earth will look to space for the power it needs.

  19. ESA's satellite communications programme

    Science.gov (United States)

    Bartholome, P.

    1985-02-01

    The developmental history, current status, and future plans of the ESA satellite-communications programs are discussed in a general survey and illustrated with network diagrams and maps. Consideration is given to the parallel development of national and European direct-broadcast systems and telecommunications networks, the position of the European space and electronics industries in the growing world market, the impact of technological improvements (both in satellite systems and in ground-based networks), and the technological and commercial advantages of integrated space-terrestrial networks. The needs for a European definition of the precise national and international roles of satellite communications, for maximum speed in implementing such decisions (before the technology becomes obsolete), and for increased cooperation and standardization to assure European equipment manufacturers a reasonable share of the market are stressed.

  20. Geostationary satellites collocation

    CERN Document Server

    Li, Hengnian

    2014-01-01

    Geostationary Satellites Collocation aims to find solutions for deploying a safe and reliable collocation control. Focusing on the orbital perturbation analysis, the mathematical foundations for orbit and control of the geostationary satellite are summarized. The mathematical and physical principle of orbital maneuver and collocation strategies for multi geostationary satellites sharing with the same dead band is also stressed. Moreover, the book presents some applications using the above algorithms and mathematical models to help readers master the corrective method for planning station keeping maneuvers. Engineers and scientists in the fields of aerospace technology and space science can benefit from this book. Hengnian Li is the Deputy Director of State Key Laboratory of Astronautic Dynamics, China.

  1. Satellite oceanography - The instruments

    Science.gov (United States)

    Stewart, R. H.

    1981-01-01

    It is pointed out that no instrument is sensitive to only one oceanographic variable; rather, each responds to a combination of atmospheric and oceanic phenomena. This complicates data interpretation and usually requires that a number of observations, each sensitive to somewhat different phenomena, be combined to provide unambiguous information. The distinction between active and passive instruments is described. A block diagram illustrating the steps necessary to convert data from satellite instruments into oceanographic information is included, as is a diagram illustrating the operation of a radio-frequency radiometer. Attention is also given to the satellites that carry the various oceanographic instruments.

  2. Oceanography from satellites

    Science.gov (United States)

    Wilson, W. S.

    1981-01-01

    It is pointed out that oceanographers have benefited from the space program mainly through the increased efficiency it has brought to ship operations. For example, the Transit navigation system has enabled oceanographers to compile detailed maps of sea-floor properties and to more accurately locate moored subsurface instrumentation. General descriptions are given of instruments used in satellite observations (altimeter, color scanner, infrared radiometer, microwave radiometer, scatterometer, synthetic aperture radar). It is pointed out that because of the large volume of data that satellite instruments generate, the development of algorithms for converting the data into a form expressed in geophysical units has become especially important.

  3. Satellites orbits and missions

    CERN Document Server

    Capderou, Michel

    2006-01-01

    Introduction Keplerian motion 1.1 Preamble 1.2 Acceleration 1.3 Central acceleration 1.4 Newtonian acceleration 1.5 Keplerian motion : trajectory and period 1.6 The three anomalies 1.7 Representation of the anomalies 1.8 Integrals of motion 1.9 Historical note on universal attraction 1.10 Annex : Ellipses Satellites on keplerian orbit 2.1 Gravitational field 2.2 The N-body and the two-body problem 2.3 Orbital parameters 2.4 Case of quasi-circular orbits 2.5 Keplerian period Satellites on real o

  4. GPS satellite surveying

    CERN Document Server

    Leick, Alfred; Tatarnikov, Dmitry

    2015-01-01

    THE MOST COMPREHENSIVE, UP-TO-DATE GUIDE ON GPS TECHNOLOGY FOR SURVEYING Three previous editions have established GPS Satellite Surveying as the definitive industry reference. Now fully updated and expanded to reflect the newest developments in the field, this Fourth Edition features cutting-edge information on GNSS antennas, precise point positioning, real-time relative positioning, lattice reduction, and much more. Expert authors examine additional tools and applications, offering complete coverage of geodetic surveying using satellite technologies. The past decade has seen a major evolut

  5. Multispectral satellite image understanding

    CERN Document Server

    Unsalan, Cem

    2011-01-01

    This book presents a comprehensive review of image processing methods, for the analysis of land use in residential areas. Combining a theoretical framework with highly practical applications, this book describes a system for the effective detection of single houses and streets in very high resolution. It features a Foreword by Prof. Dr. Peter Reinartz of the German Aerospace Center. This title provides end-of-chapter summaries and review questions; presents a detailed review on remote sensing satellites; examines the multispectral information that can be obtained from satellite images, with a

  6. MIST Student Satellite

    OpenAIRE

    Gårdebäck, Agnes; Haugdahl, Vincent

    2015-01-01

    In this report, parts of the systems engineering of a spacecraft are presented. In 2014 the Royal Institute of Technology KTH initiated a new space technology and research platform, the KTH Space Centre. The first student project at KTH Space Centre was the MIST student satellite with the scope of the system design and construction of a real satellite due for launch in 2017. As part of the MIST project this bachelor thesis covers the mission analysis and parts of the system design. The system...

  7. Satellite Control Laboratory

    OpenAIRE

    Wisniewski, Rafal; Bak, Thomas

    2001-01-01

    The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft is suspended on an air bearing, and rotates freely in 3 degrees of freedom. In order to avoid any influence of the gravitational force the centre of mass of the satellite is placed in the geometric centre of...

  8. Advances in satellite oceanography

    Science.gov (United States)

    Brown, O. B.; Cheney, R. E.

    1983-01-01

    Technical advances and recent applications of active and passive satellite remote sensing techniques to the study of oceanic processes are summarized. The general themes include infrared and visible radiometry, active and passive microwave sensors, and buoy location systems. The surface parameters of sea surface temperature, windstream, sea state, altimetry, color, and ice are treated as applicable under each of the general methods.

  9. Learning Through Satellite Broadcasting

    Science.gov (United States)

    Krishnamoorthy, P. V.

    1975-01-01

    SITE is an experimental project which would provide vital inputs in designing and executing a satellite-based instructional television system, particularly in rural areas, to stimulate national development in India with important managerial, economic, technological, and social implications. (Author/BP)

  10. Observations of artificial satellites

    Directory of Open Access Journals (Sweden)

    A. MAMMANO

    1964-06-01

    Full Text Available The following publication gives the results of photographic
    observations of artificial satellites made at Asiago during the second
    and third year of this programme. The fixed camera technique and that
    with moving film (the latter still in its experimental stage have been used.

  11. Man-made Satellites

    Institute of Scientific and Technical Information of China (English)

    郝昌明

    2005-01-01

    If you watch the sky about an hour after the sun goes down, you may see some “moving stars”. But they're not real stars. They're manmade satellites (卫星). And the biggest of all is the International Space Station (ISS国际空间站).

  12. Experimental Satellite Quantum Communications.

    Science.gov (United States)

    Vallone, Giuseppe; Bacco, Davide; Dequal, Daniele; Gaiarin, Simone; Luceri, Vincenza; Bianco, Giuseppe; Villoresi, Paolo

    2015-07-24

    Quantum communication (QC), namely, the faithful transmission of generic quantum states, is a key ingredient of quantum information science. Here we demonstrate QC with polarization encoding from space to ground by exploiting satellite corner cube retroreflectors as quantum transmitters in orbit and the Matera Laser Ranging Observatory of the Italian Space Agency in Matera, Italy, as a quantum receiver. The quantum bit error ratio (QBER) has been kept steadily low to a level suitable for several quantum information protocols, as the violation of Bell inequalities or quantum key distribution (QKD). Indeed, by taking data from different satellites, we demonstrate an average value of QBER=4.6% for a total link duration of 85 s. The mean photon number per pulse μ_{sat} leaving the satellites was estimated to be of the order of one. In addition, we propose a fully operational satellite QKD system by exploiting our communication scheme with orbiting retroreflectors equipped with a modulator, a very compact payload. Our scheme paves the way toward the implementation of a QC worldwide network leveraging existing receivers. PMID:26252672

  13. Perception via satellite

    Science.gov (United States)

    Robinove, Charles J.

    1970-01-01

    The earth resources observation satellite (EROS) program in the Department of the Interior is intended to gather and use data from satellites and aircraft on natural and man-made features of the earth's surface. Earth resources technology satellite will provide the EROS program with data for use in dealing with natural resource problems and understanding the interaction between man and the environment. Applications will include studies of tectonic features, hydrologic problems, location of fish schools, determination of the conditions of range land, mapping land use for urban planning, studies of erosion and change along coastlines and major streams, and inventories of land use and land forms. In addition, the ERTS data may be used for detecting forest and crop diseases and inventorying crops. The ERTS satellite will be in a polar, sun-synchronous orbit so that each point on the earth's surface will be sensed every 17 to 20 days, at the same time of day. Multispectral photography is being investigated for its usefulness in hydrology. Side-looking airborne radar has not yet been widely used in hydrologic studies, although it is an excellent tool for all-weather, day or night, coverage of large areas. Other techniques being investigated include passive microwave radiometry, ultraviolet and visible stimulated luminescence, and absorption spectroscopy.

  14. Defense Meteorological Satellite Program (DMSP)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Defense Meteorological Satellite Program (DMSP) satellites collect visible and infrared cloud imagery as well as monitoring the atmospheric, oceanographic,...

  15. DFH Satellite Co.,Ltd.

    Institute of Scientific and Technical Information of China (English)

    SunQing

    2004-01-01

    DFH Satellite Co.,Ltd. is a hi-tech enterprise founded and sponsored by China Aerospace Science and Technology Corporation(CASC) and one of CASC subsidiaries,China Academy of Space Technology (CAST). The company is mainly engaged in the research and development of small satellites and micro-satellites, Osystem designs and product development for satellite application projects as well as the international exchanges and cooperation.

  16. Cooperative and cognitive satellite systems

    CERN Document Server

    Chatzinotas, Symeon; De Gaudenzi, Riccardo

    2015-01-01

    Cooperative and Cognitive Satellite Systems provides a solid overview of the current research in the field of cooperative and cognitive satellite systems, helping users understand how to incorporate state-of-the-art communication techniques in innovative satellite network architectures to enable the next generation of satellite systems. The book is edited and written by top researchers and practitioners in the field, providing a comprehensive explanation of current research that allows users to discover future technologies and their applications, integrate satellite and terrestrial systems

  17. Thematic mapping from satellite imagery

    CERN Document Server

    Denègre, J

    2013-01-01

    Thematic Mapping from Satellite Imagery: A Guidebook discusses methods in producing maps using satellite images. The book is comprised of five chapters; each chapter covers one stage of the process. Chapter 1 tackles the satellite remote sensing imaging and its cartographic significance. Chapter 2 discusses the production processes for extracting information from satellite data. The next chapter covers the methods for combining satellite-derived information with that obtained from conventional sources. Chapter 4 deals with design and semiology for cartographic representation, and Chapter 5 pre

  18. Satellite Control Laboratory

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Bak, Thomas

    2001-01-01

    The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft......-axis magnetometer, three piezoelectric gyros, and four reaction wheels in a tetrahedron configuration. The operation of the spacecraft is fully autonomous. The data flow between the transducers and the onboard computer placed physically outside the satellite is provided by a radio link. The purpose...... of the laboratory is to conduct dynamic tests of the control and attitude determination algorithms during nominal operation and in abnormal conditions. Further it is intended to use SatLab for validation of various algorithms for fault detection, accommodation and supervisory control. Different mission objectives...

  19. Declassified Intelligence Satellite Photographs

    Science.gov (United States)

    U.S. Geological Survey

    2008-01-01

    Declassified photographs from U.S. intelligence satellites provide an important worldwide addition to the public record of the Earth's land surface. This imagery was released to the National Archives and Records Administration (NARA) and the U.S. Geological Survey (USGS) in accordance with Executive Order 12951 on February 23, 1995. The NARA has the original declassified film and a viewing copy. The USGS has another copy of the film to complement the Landsat archive. The declassified collection involves more than 990,000 photographs taken from 1959 through 1980 and was released on two separate occasions: February 1995 (Declass 1) and September 2002 (Declass 2). The USGS copy is maintained by the Earth Resources Observation and Science (EROS) Center, near Sioux Falls, South Dakota. Both the NARA and EROS provide public access to this unique collection that extends the record of land-surface change back another decade from the advent of the Landsat program that began satellite operations in 1972.

  20. Small Satellites Big Business?

    OpenAIRE

    A. Marchetto, Carl

    2008-01-01

    Biography-Carl A. Marchetto is Senior Vice President and President, ATK Space Systems for Alliant Tech¬systems (ATK). Prior to joining ATK in January 2008, Carl was Executive Vice President and General Manager Space Sys¬tems group for Orbital Sciences, where he led an organization designing, building, and servicing communication, space research and earth imaging satellites for commercial, gov¬ernment and academic customers. Carl’s previous experience includes a decade at Eastman Kodak that sa...

  1. Satellite servicing economic study

    Science.gov (United States)

    1990-01-01

    Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Therefore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options and potential economic benefits.

  2. STARBANDSM - Satellite Internet Service

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    The Internet has become one of the most important communication systems in the present. However people across the continental United States have not been able to get broadband Internet service. StarBand service, with no special phone lines or cable modems required is a feasible solution. StarBand is America’s first consumer two-way, always-on, high-speed satellite Internet service.

  3. Laser ICESat-satellite

    OpenAIRE

    Webredactie M&C

    2010-01-01

    The ICESat satellite, launched in 2003, is equipped with an altimeter that uses a laser beam to determine its distance from the Earth. Forty short laser pulses per second hit an area of Earth's surface that is 70 metres in diameter. These measurement circles are 170 metres apart. Each measurement represents the average vertical shift in the 70m measurement circle. ICESat can detect variations of 1.5 cm a year or more in the elevation of the ice surface.

  4. SAC-A Satellite

    OpenAIRE

    Machado, Marcos; Roggero, Edgardo; Alonso, Roberto; Anigstein, Pablo; Caruso, Daniel; Bratina, Juan; Vega, Julio; Pena, Ricardo Sanchez

    1996-01-01

    The SAC-A is a Low Cost - Short Schedule - Small Bus dedicated to test equipment and new technologies which may be used in operational or scientific missions with more immunity to failures. The opportunity to fly in a low orbit for a reasonable period of time, allows the characterization of the behavior of this new instrumentation in real world applications and also to compute performance. The 68 kg satellite will have an almost octagonal configuration to be fitted within the Hitchhiker Motor...

  5. Binary Satellite Galaxies

    CERN Document Server

    Evslin, Jarah

    2013-01-01

    Suggestions have appeared in the literature that the following five pairs of Milky Way and Andromeda satellite galaxies are gravitationally bound: Draco and Ursa Minor, Leo IV and V, Andromeda I and III, NGC 147 and 185, and the Magellanic clouds. Under the assumption that a given pair is gravitationally bound, the Virial theorem provides an estimate of its total mass and so its instantaneous tidal radius. For all of these pairs except for the Magellanic clouds the resulting total mass is 2 to 4 orders of magnitude higher than that within the half light radius. Furthermore in the case of each pair except for Leo IV and Leo V, the estimated tidal radius is inferior to the separation between the two satellites. Therefore all or almost all of these systems are not gravitationally bound. We note several possible explanations for the proximities and similar radial velocities of the satellites in each pair, for example they may have condensed from the same infalling structure or they may be bound by a nongravitatio...

  6. Percepção astronómica de um grupo de alunos do ensino médio de uma escola da rede estadual de São Paulo

    Science.gov (United States)

    de Oliveria, E. F.; Voelzke, M. R.

    2009-03-01

    Sendo a Astronomia uma das cièncias mais antigas da humanidade, e considerando sua importáncia histórica e cultural, é de extrema releváncia que tópicos relacionados a ela sejam tratados nas escolas. Embora os Parámetros Curriculares Nacionais do Ensino Médio (PCN-EM) e as Orientaçiacute;es Complementares aos Parámetros (PCN+) apontem a importáncia de uma abordagem significativa de conceitos relacionados à Astronomia nas aulas de Física, muitos estudantes terminam o Ensino Médio (EM) sem compreender a razão de certos acontecimentos de origem celeste, ainda que estes façam parte de seu cotidiano e sejam alvos da curiosidade natural dos jovens. Da observação dessa curiosidade em alunos de uma escola pública paulista, na cidade de Suzano, surgiu o interesse em investigar os conhecimentos básicos em Astronomia dos alunos do Ensino Médio desta escola, constituindo-se este como principal objetivo desta pesquisa. Para tanto foi elaborado um questionário de múltipla escolha aplicado inicialmente a 34 alunos do primeiro ano e, posteriormente, a mais 310, distribuídos entre as très séries do Ensino Médio dos períodos matutino e noturno. Dessa forma, observou-se que 73,9% dos estudantes identificaram o Sol como sendo uma estrela, 67,1% mostraram compreender a sucessão entre dia e noite e 52,3% relacionaram o Big Bang à origem do Universo. Em contrapartida, apenas 34,5% relacionaram as estaçíes do ano à inclinação do eixo de rotação da Terra, 21,3% indicaram a influència gravitacional simultánea da Lua e do Sol como responsável pelo fenòmeno das marés, 24,5% indicaram corretamente quais são os objetos celestes mais próximos da Terra, 36,1% identificaram ano-luz como uma medida de distáncia e 34,2% reconheceram as estrelas cadentes como meteoros, evidenciando-se assim o pequeno discernimento dos estudantes quanto aos fenòmenos e termos astronòmicos do cotidiano. Além disso, foram comparadas as respostas de alun! os de diferentes s

  7. Nicolás Mascardi e a carta-relación de 1670: uma análise preliminar das observações astronômicas realizadas pelo missionário jesuíta = Nicolás Mascardi and the carta-relación de 1670: a preliminary analysis of astronomical observations carried out by the jesuit missionary

    Directory of Open Access Journals (Sweden)

    Biehl, Maico

    2014-01-01

    Full Text Available O presente artigo apresenta os resultados preliminares da pesquisa que venho desenvolvendo como bolsista PIBIC/CNPq junto ao projeto “Uma ordem de homens de religião e de ciência: difusão, produção e circulação de saberes e práticas científicas pela Companhia de Jesus (América meridional, séculos XVII e XVIII”. O subprojeto prevê o contato com as teorias astronômicas vigentes no Seiscentos e no Setecentos, com as obras de Astronomia que integravam os acervos da Ordem e com os estudos produzidos por missionários já no Novo Mundo. Assim como, a reconstituição das trajetórias de jesuítas que realizaram observações astronômicas nas reduções em que atuaram, compartilhando os seus estudos através da prática epistolar ou por meio de obras. Neste artigo, especificamente, me detenho em reconstituir brevemente a trajetória do jesuíta Nicolas Mascardi, destacando as observações astronômicas que realizou na América e as suas comunicações com demais estudiosos da astronomia.

  8. Understanding satellite navigation

    CERN Document Server

    Acharya, Rajat

    2014-01-01

    This book explains the basic principles of satellite navigation technology with the bare minimum of mathematics and without complex equations. It helps you to conceptualize the underlying theory from first principles, building up your knowledge gradually using practical demonstrations and worked examples. A full range of MATLAB simulations is used to visualize concepts and solve problems, allowing you to see what happens to signals and systems with different configurations. Implementation and applications are discussed, along with some special topics such as Kalman Filter and Ionosphere. W

  9. UCI Satellite-II

    OpenAIRE

    Carroll, Keegan; Chen, Geoffrey Hsiao-Wei; Timilsina, Navin; Walter, Scott; Fimbres, Cristhian; Mai, Zaw; Phung, Diane; Kampley, Leann; Lasquete, Kevin W.S.; Patel, Akash; Dunford , Amy; Deason, Ross; Salazar, Eric Salaza; Tarif , Abdullaah R.; Shojaei, Kamran

    2013-01-01

    The principal idea involves the utilization of existing solar radiation to degrade model pollutants (midodrine and humic acid) in aqueous solution.  The decomposition of said pollutants will be observed through a photochemical effect known as “fluorescence”, whereby substances emit light after absorbing electromagnetic radiation.  The experiment will be carried out on a Class 2U Cube Satellite; hence the designation of “UCISAT-2.”  In addition, UCISAT-2 will utilize an electric propulsion sys...

  10. China Satellite Navigation Conference

    CERN Document Server

    Liu, Jingnan; Fan, Shiwei; Wang, Feixue

    2016-01-01

    These Proceedings present selected research papers from CSNC2016, held during 18th-20th May in Changsha, China. The theme of CSNC2016 is Smart Sensing, Smart Perception. These papers discuss the technologies and applications of the Global Navigation Satellite System (GNSS), and the latest progress made in the China BeiDou System (BDS) especially. They are divided into 12 topics to match the corresponding sessions in CSNC2016, which broadly covered key topics in GNSS. Readers can learn about the BDS and keep abreast of the latest advances in GNSS techniques and applications.

  11. Satellite Network Hacking & Security Analysis

    Directory of Open Access Journals (Sweden)

    Adam Ali.Zare Hudaib

    2016-04-01

    Full Text Available Satellites play a significant role in communication, early warning systems, global broadcasting, meteorology, navigation, reconnaissance, remote sensing, and surveillance.Satellite services cover practically every sector, from mobile cellular communication to telemedicine, so any interference with them could have a serious effect. Satellites are a strategic asset for any country and are considered as “critical infrastructure,” therefore they are considerable as privileged targets for a possible cyber attack.

  12. Vibration Testing for Small Satellites

    OpenAIRE

    Wilson, Delbert

    1989-01-01

    Most people involved in the design and construction of small satellites are unfamiliar with vibration testing. Yet most satellites undergo vibration testing to qualify them for flight. Some familiarity with the basic aspects of vibration testing is needed to insure that a vibration test on a satellite is valid. This paper sets forth the basic equipment, practices and concepts of vibration testing. It provides guidelines for specifying a vibration test, designing fixtures, attaching instrument...

  13. Living antennas on communication satellites

    DEFF Research Database (Denmark)

    Lumholt, Michael

    2003-01-01

    Crises change the global pattern of communication. The communications problems occur because the satellites are optimized to cover specific geographic areas, and these areas cannot be altered once the satellites are in Earth orbit. An effective solution to the problem is to equip communication sa...... satellites with "living" antennas that can adjust their radiation coverage areas according to the new demands. The development of living antennas is, therefore, among the focus areas identified and supported by the European Space Agency, ESA....

  14. The power relay satellite

    Science.gov (United States)

    Glaser, Peter E.

    The availability and use of renewable energy sources compatible with reducing risks to the global environment are key to sustainable development. Large-scale, renewable energy resources at undeveloped or underutilized sites are potentially available on several continents. The Power Relay Satellite (PRS) concept has the potential to access these remote energy resources by coupling primary electricity generation from terrestrial transmission lines. A global PRS network can be envisioned to provide a high degree of flexibility for supplying energy demands worldwide with wireless power transmitted from sites on Earth to geosynchronous orbit and then reflected to receivers interfacing with terrestrial power transmision networks. Past developments in wireless power transmission (WPT) are reviewed and recent successful results are noted. The origins of the PRS concept, and a possible configuration are discussed, principles of WPT at microwave frequencies, functional requirements, and system design contraints are outlined, and space transportation concepts presented. PRS assessments including applicable technologies, economic projections, and societal issues are highlighted. It is concluded that the PRS provides a promising option to access renewable resources at great distances from major markets, and represents an important stage in the future development in the future of solar power satellites.

  15. Solar power satellite

    Science.gov (United States)

    Davis, H. P.

    1978-01-01

    The solar power satellite (SPS) concept, under evaluation by NASA since 1974, is discussed. A typical system providing a total of 10,000 MW of electrical power to the ground receiving stations is considered. Energy conversion systems, including the photovoltaic device category using single-crystal silicon cells, are taken into account, as are the 2.45-GHz microwave power-transmission link and the ground receiver (or rectenna). Concepts involving space construction of the satellite's large structures (5 x 25 km) are described, noting that a process similar to the familiar roll-forming of light sheet metal parts has been adapted to the space environment. Transportation vehicles are discussed, including the Space Shuttle planned to reach 60 flights per year by the mid 1980's. Electrical power forecasts and advanced systems cost projections are analyzed, together with a description of costs estimates. The indirect economics of energy research and development, and the present NASA/DOE SPS program are noted.

  16. Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)

    Science.gov (United States)

    Hoder, Douglas; Bergamo, Marcos

    1996-01-01

    The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

  17. Satellite-based internet: A tutorial

    OpenAIRE

    Hu, Y.; Li, VOK

    2001-01-01

    In a satellite-based Internet system, satellites are used to interconnect heterogeneous network segments and to provide ubiquitous direct Internet access to homes and businesses. This article presents satellite-based Internet architectures and discusses multiple access control, routing, satellite transport, and integrating satellite networks into the global Internet.

  18. Satellite Control Laboratory

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Bak, Thomas

    2001-01-01

    The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft is...... laboratory is to conduct dynamic tests of the control and attitude determination algorithms during nominal operation and in abnormal conditions. Further it is intended to use SatLab for validation of various algorithms for fault detection, accommodation and supervisory control. Different mission objectives...... can be implemented in the laboratory, e.g. three-axis attitude control, slew manoeuvres, spins stabilization using magnetic actuation and/or reaction wheels. The spacecraft attitude can be determined applying magnetometer measurements....

  19. The solar power satellite

    Energy Technology Data Exchange (ETDEWEB)

    Combes, P.F.

    1982-01-01

    The construction, launch, components, and operations of satellite solar power systems (SSPS) for direct beaming of solar energy converted to electricity to earth stations are outlined. The reference designs of either Si or concentrator GaAs solar cell assemblies large enough to project 5 GW of power are described. The beam will be furnished by klystrons or amplitrons for reception by rectennas on earth. Conforming to the law of amplitude and the equiphase law will permit high efficiencies, pointing accuracy, and low power deposition/sq cm, thus avoiding environmental problems, although some telecommunications systems may suffer interference. The construction of the dipole rectenna grid is sketched, noting that one receiver would be an ellipse sized at 10 x 13 km. Various forms of pollution which could result from the construction of an SSPS are examined.

  20. Integrated Satellite-HAP Systems

    DEFF Research Database (Denmark)

    Cianca, Ernestina; De Sanctis, Mauro; De Luise, Aldo;

    2005-01-01

    Thus far, high-altitude platform (HAP)-based systems have been mainly conceived as an alternative to satellites for complementing the terrestrial network. This article aims to show that HAP should no longer be seen as a competitor technology by investors of satellites, but as a key element for an...

  1. Multicast Routing in Satellite Network

    Institute of Scientific and Technical Information of China (English)

    郭惠玲; 宋姝; 李磊; 刘志涛; 郭鹏程

    2004-01-01

    There are some problems in the dual-layer satellite MPLs metworks to be composed of LEO and MEO. In order to solve the problems, this paper presents a plan by means of unicast LSP to implement multicast in the dual-layer satellite MPLs networks. It has advantages of saving space and reducing extra charge.

  2. Accumulation of satellites

    International Nuclear Information System (INIS)

    Formation and evolution of circumplanetary satellite swarms are investigated. Characteristic times of various processes are estimated. The characteristic time for the accumulation of the bodies in the swarm was several orders of magnitude shorter than that of the planet, i.e. than the time of the replenishment of the material by the swarm (108 yr). The model of the accumulation of the swarm is constructed taking into account the increase of its mass due to trapping of heliocentrically moving particles and its decrease due to outfall of the inner part of the swarm onto the growing planet. The accumulation of circumplanetary bodies is also considered. The main features of the evolution of the swarm essentially depend on the size distribution of bodies in the swarm and in the zone of the planet and also on the degree of the concentration of the swarm mass toward the planet. If the sum of the exponents of the inverse power laws of these distributions is less than 7, the model of the transparent swarm developed in this paper should be preferred. When this sum is greater than 7, the model of opaque swarm suggested by A. Harris and W.M. Kaula is better. There is predominant trapping of small particles into the swarm due to their more frequent collisions. Optical thickness of the protoplanetary cloud in radial direction is estimated. It is shown that at the final stage of the planetary accumulation, the cloud was semitransparent in the region of terrestrial planets and volatile substances evaporated at collisions could be swept out from the outer parts of the satellite swarm by the solar wind

  3. Sky alert! when satellites fail

    CERN Document Server

    Johnson, Les

    2013-01-01

    How much do we depend on space satellites? Defense, travel, agriculture, weather forecasting, mobile phones and broadband, commerce...the list seems endless. But what would our live be like if the unimaginable happened and, by accident or design, those space assets disappeared? Sky Alert! explores what our world would be like, looking in turn at areas where the loss could have catastrophic effects. The book - demonstrates our dependence on space technology and satellites; - outlines the effect on our economy, defense, and daily lives if satellites and orbiting spacecraft were destroyed; - illustrates the danger of dead satellites, spent rocket stages, and space debris colliding with a functioning satellites; - demonstrates the threat of dramatically increased radiation levels associated with geomagnetic storms; - introduces space as a potential area of conflict between nations.

  4. Induction studies with satellite data

    DEFF Research Database (Denmark)

    Olsen, Nils

    1999-01-01

    analysis of the geomagnetic field is performed, and the Q-response, which is the transfer function between the internal (induced) and the external (inducing) expansion coefficients is determined for a specific frequency. In the second approach, known as the geomagnetic depth sounding method, the C...... paper reviews and discusses the possibilities for induction studies using high-precision magnetic measurements from low-altitude satellites. The different methods and various transfer functions are presented, with special emphasis on the differences in analysing data from ground stations and from...... satellites. The results of several induction studies with scalar satellite data (from the POGO satellites) and with vector data (from the Magsat mission) demonstrate the ability to probe the Earth's conductivity from space. However, compared to the results obtained with ground data the satellite results are...

  5. Polar-Orbiting Satellite (POES) Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from camera systems or radiometer instruments on satellites in orbit around the poles. Satellite campaigns include...

  6. Expresiones de origen náutico en el nacimiento de las distintas formas de volar: aerostación, aviación y astronáutica Expressions of marine origin in the birth of the different ways to fly: aeronautics, aviation and astronautics

    OpenAIRE

    Lorena M. A. de-Matteis

    2012-01-01

    En la comunicación cotidiana se puede observar que el nivel léxico-semántico liga a la aerostación, la aviación y la astronáutica en una relación de continuidad de base analógica. Esta conexión se funda, en primer lugar, por procesos de trasvase terminológico de las respectivas técnicas y, luego, en la adopción social de las unidades léxicas de origen técnico, por el empleo de metáforas para explicar la nueva realidad. De esta manera, el análisis léxico muestra que aerostación, aviación y exp...

  7. The exterior tidal potential acting on a satellite. [satellite orbits/satellite perturbation - gravitation effects

    Science.gov (United States)

    Musen, P.

    1975-01-01

    A theory is presented that points out the existence of several long period and 'cross effects' in the coefficients in the expansion of the geopotential and in the motion of satellites. The tidal potential, defined as small periodic variations in the geopotential, was calculated. The influence of these geopotential variations on satellite perturbation is examined. Spherical harmonics were employed.

  8. Theory of satellite geodesy applications of satellites to geodesy

    CERN Document Server

    Kaula, William M

    2000-01-01

    The main purpose of this classic text is to demonstrate how Newtonian gravitational theory and Euclidean geometry can be used and developed in the earth's environment. The second is to collect and explain some of the mathematical techniques developed for measuring the earth by satellite.Book chapters include discussions of the earth's gravitational field, with special emphasis on spherical harmonies and the potential of the ellipsoid; matrices and orbital geometry; elliptic motion, linear perturbations, resonance, and other aspects of satellite orbit dynamics; the geometry of satellite obser

  9. Multi-mission Satellite Management

    Science.gov (United States)

    Jamilkowski, M. L.; Teter, M. A.; Grant, K. D.; Dougherty, B.; Cochran, S.

    2015-12-01

    NOAA's next-generation environmental satellite, the Joint Polar Satellite System (JPSS) replaces the current Polar-orbiting Operational Environmental Satellites (POES). JPSS satellites carry sensors which collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The first JPSS satellite was launched in 2011 and is currently NOAA's primary operational polar satellite. The JPSS ground system is the Common Ground System (CGS), and provides command, control, and communications (C3) and data processing (DP). A multi-mission system, CGS provides combinations of C3/DP for numerous NASA, NOAA, DoD, and international missions. In preparation for the next JPSS satellite, CGS improved its multi-mission capabilities to enhance mission operations for larger constellations of earth observing satellites with the added benefit of streamlining mission operations for other NOAA missions. CGS's multi-mission capabilities allows management all of assets as a single enterprise, more efficiently using ground resources and personnel and consolidating multiple ground systems into one. Sophisticated scheduling algorithms compare mission priorities and constraints across all ground stations, creating an enterprise schedule optimized to mission needs, which CGS executes to acquire the satellite link, uplink commands, downlink and route data to the operations and data processing facilities, and generate the final products for delivery to downstream users. This paper will illustrate the CGS's ability to manage multiple, enterprise-wide polar orbiting missions by demonstrating resource modeling and tasking, production of enterprise contact schedules for NOAA's Fairbanks ground station (using both standing and ad hoc requests), deconflicting resources due to ground outages, and updating resource allocations through dynamic priority definitions.

  10. Advanced Communications Technology Satellite (ACTS)

    Science.gov (United States)

    Gedney, Richard T.; Schertler, Ronald J.

    1989-06-01

    The NASA Advanced Communications Technology Satellite (ACTS) was conceived to help maintain U.S. leadership in the world's communications-satellite market. This experimental satellite is expected to be launched by NASA in 1992 and to furnish the technology necessary for establishing very small aperture terminal digital networks which provide on-demand full-mesh connectivity, and 1.544-MBPS services with only a single hop. Utilizing on-board switching and processing, each individual voice or data circuit can be separately routed to any location in the network. This paper provides an overview of the ACTS and discusses the value of the technology for future communications systems.

  11. Magnetic Satellite Missions and Data

    DEFF Research Database (Denmark)

    Olsen, Nils; Kotsiaros, Stavros

    2011-01-01

    Although the first satellite observations of the Earth’s magnetic field were already taken more than 50 years ago, continuous geomagnetic measurements from space are only available since 1999. The unprecedented time-space coverage of this recent data set opened revolutionary new possibilities for...... exploring the Earth’s magnetic field from space. In this chapter we discuss characteristics of satellites measuring the geomagnetic field and report on past, present and upcoming magnetic satellite missions. We conclude with some basics about space magnetic gradiometry as a possible path for future...

  12. Satellite communications principles and applications

    CERN Document Server

    Calcutt, David

    1994-01-01

    Satellites are increasingly used for global communications, as well as for radio and television transmissions. With the growth of mobile communications, and of digital technology, the use of satellite systems is set to expand substantially and already all students of electronics or communications engineering must study the subject.This book steers a middle path between offering a basic understanding of the process of communication by satellite and the methodology used; and the extensive mathematical analysis normally adopted in similar texts. It presents the basic concepts, using as mu

  13. Leucocytes, cytokines and satellite cells

    DEFF Research Database (Denmark)

    Paulsen, Gøran; Mikkelsen, Ulla Ramer; Raastad, Truls;

    2012-01-01

    -damaging exercise', primarily eccentric exercise. We review the evidence for the notion that the degree of muscle damage is related to the magnitude of the cytokine response. In the third and final section, we look at the satellite cell response to a single bout of eccentric exercise, as well as the role of the...... variation in individual responses to a given exercise should, however be expected. The link between cytokine and satellite cell responses and exercise-induced muscle damage is not so clear The systemic cytokine response may be linked more closely to the metabolic demands of exercise rather than muscle...... damage. With the exception of IL-6, the sources of systemic cytokines following exercise remain unclear The satellite cell response to severe muscle damage is related to regeneration, whereas the biological significance of satellite cell proliferation after mild damage or non-damaging exercise remains...

  14. Virtual Satellite Integration Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An integrated environment for rapid design studies of small satellite missions will be developed. This environment will be designed to streamline processes at the...

  15. Visual Data Analysis for Satellites

    Science.gov (United States)

    Lau, Yee; Bhate, Sachin; Fitzpatrick, Patrick

    2008-01-01

    The Visual Data Analysis Package is a collection of programs and scripts that facilitate visual analysis of data available from NASA and NOAA satellites, as well as dropsonde, buoy, and conventional in-situ observations. The package features utilities for data extraction, data quality control, statistical analysis, and data visualization. The Hierarchical Data Format (HDF) satellite data extraction routines from NASA's Jet Propulsion Laboratory were customized for specific spatial coverage and file input/output. Statistical analysis includes the calculation of the relative error, the absolute error, and the root mean square error. Other capabilities include curve fitting through the data points to fill in missing data points between satellite passes or where clouds obscure satellite data. For data visualization, the software provides customizable Generic Mapping Tool (GMT) scripts to generate difference maps, scatter plots, line plots, vector plots, histograms, timeseries, and color fill images.

  16. Commercial satellite broadcasting for Europe

    Science.gov (United States)

    Forrest, J. R.

    1988-12-01

    A review is presented of the current television broadcasting situation in European countries, which involves a varied mix of terrestrial VHF or UHF systems and cable networks. A small market has emerged in Europe for receivers using the low-power telecommunications satellite transmission between the program providers and cable network companies. This is expected to change with the launch of medium-power pan-European telecommunication satellites (e.g. ASTRA, EUTELSAT II), which are now directly addressing the market of home reception. DBS (direct broadcast satellite) in the UK, using the D-MAC transmission standard, will offer three additional television channels, data broadcasting services, and a planned evolution to compatible forms of wide-screen, high-definition television. Comments are given on receiver and conditional access system standardization. Some views are expressed on satellite broadcasting as part of an overall broadcasting framework for the future.

  17. Virtual Satellite Integration Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advatech Pacific proposes to develop a Virtual Satellite Integration Environment (VSIE) for the NASA Ames Mission Design Center. The VSIE introduces into NASA...

  18. Biogeography based Satellite Image Classification

    CERN Document Server

    Panchal, V K; Kaur, Navdeep; Kundra, Harish

    2009-01-01

    Biogeography is the study of the geographical distribution of biological organisms. The mindset of the engineer is that we can learn from nature. Biogeography Based Optimization is a burgeoning nature inspired technique to find the optimal solution of the problem. Satellite image classification is an important task because it is the only way we can know about the land cover map of inaccessible areas. Though satellite images have been classified in past by using various techniques, the researchers are always finding alternative strategies for satellite image classification so that they may be prepared to select the most appropriate technique for the feature extraction task in hand. This paper is focused on classification of the satellite image of a particular land cover using the theory of Biogeography based Optimization. The original BBO algorithm does not have the inbuilt property of clustering which is required during image classification. Hence modifications have been proposed to the original algorithm and...

  19. Radio interferometry and satellite tracking

    CERN Document Server

    Kawase, Seiichiro

    2012-01-01

    Worldwide growth of space communications has caused a rapid increase in the number of satellites operating in geostationary orbits, causing overcrowded orbits. This practical resource is designed to help professionals overcome this problem. This timely book provides a solid understanding of the use of radio interferometers for tracking and monitoring satellites in overcrowded environments. Practitioners learn the fundamentals of radio interferometer hardware, including antennas, receiving equipment, signal processing and phase detection, and measurement accuracies. This in-depth volume describ

  20. NEGESAR: NEw GEneration Satellite Architecture

    OpenAIRE

    Boer, Fabrizio; Borghesi, Giancarlo

    2000-01-01

    Reduce to the minimum any analog-based system on board the next generation satellites and replace them with the more performing and reliable digital platforms shall be the challenge for all the Space Business World in the next decade. The micro-size NEGESAT Company (2 experienced Space Engineers) has launched, since early 99, the project called NEGESAR (NEw GEneration Satellite ARchitecture) aiming at this objective: to give the Space User a way to launch active and complex Electronic Equipme...

  1. TERSat: Trapped Energetic Radiation Satellite

    OpenAIRE

    Clements, Emily; Alvisio, Bruno; Babuscia, Alessandra; Casas, Zachary; Coffee, Brian; Giblin, Sydney; Hallock, Laura; Kingsbury, Ryan; Leaman, Michael; Lynch, Naomi; O'Connor, Michael; Qian, Elizabeth; Schmidt, Frank; de Soria-Santacruz, Maria; Sotomayor, Lionel

    2012-01-01

    Radiation damage caused by interactions with high-energy particles in the Van Allen Radiation Belts is a leading cause of component failures for satellites in low and medium Earth orbits (LEO, MEO). Very Low Frequency (VLF) electromagnetic waves have been shown to couple energy to high energy radiation belt particles and change their properties. For example, data from the IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) satellite suggest that the gap between the inner ...

  2. Existence of undiscovered Uranian satellites

    International Nuclear Information System (INIS)

    Structure in the Uranian ring system as observed in recent occultations may contain indirect evidence for the existence of undiscovered satellites. Using the Alfven and Arrhenius (1975, 1976) scenario for the formation of planetary systems, the orbital radii of up to nine hypothetical satellites interior to Miranda are computed. These calculations should provide interesting comparisons when the results from the Voyager 2 encounter with Uranus are made public. 15 refs., 1 fig., 1 tab

  3. Gaussian Entanglement Distribution via Satellite

    OpenAIRE

    Hosseinidehaj, Nedasadat; Malaney, Robert

    2014-01-01

    In this work we analyse three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in thi...

  4. Satellite medical centers project

    Science.gov (United States)

    Aggarwal, Arvind

    2002-08-01

    World class health care for common man at low affordable cost: anywhere, anytime The project envisages to set up a national network of satellite Medical centers. Each SMC would be manned by doctors, nurses and technicians, six doctors, six nurses, six technicians would be required to provide 24 hour cover, each SMC would operate 24 hours x 7 days. It would be equipped with the Digital telemedicine devices for capturing clinical patient information and investigations in the form of voice, images and data and create an audiovisual text file - a virtual Digital patient. Through the broad band connectivity the virtual patient can be sent to the central hub, manned by specialists, specialists from several specialists sitting together can view the virtual patient and provide a specialized opinion, they can see the virtual patient, see the examination on line through video conference or even PCs, talk to the patient and the doctor at the SMC and controlle capturing of information during examination and investigations of the patient at the SMC - thus creating a virtual Digital consultant at the SMC. Central hub shall be connected to the doctors and consultants in remote locations or tertiary care hospitals any where in the world, thus creating a virtual hub the hierarchical system shall provide upgradation of knowledge to thedoctors in central hub and smc and thus continued medical education and benefit the patient thru the world class treatment in the smc located at his door step. SMC shall be set up by franchisee who shall get safe business opportunity with high returns, patients shall get Low cost user friendly worldclass health care anywhere anytime, Doctors can get better meaningful selfemplyment with better earnings, flexibility of working time and place. SMC shall provide a wide variety of services from primary care to world class Global consultation for difficult patients.

  5. ARJIS satellite demonstration project

    Science.gov (United States)

    Severance, Steve; Williams, Carl

    2005-06-01

    In 2003, the California Space Authority (CSA) was provided funding by the U. S. Congress through the Defense Appropriations Act to develop a project that would demonstrate the U.S. space enterprise capability that would contribute to the effectiveness of those engaged in Homeland Security. The project was given broad latitude in selecting the area of Homeland Security to be addressed and the nature of the space technology to be applied. CSA became aware of a nascent law enforcement data-sharing project in the San Diego region known as the Automated Regional Justice Information System (ARJIS). First developed by the police departments in San Diego, ARJIS is an innovative system that shares criminal justice information among 50 federal, state, and local agencies. ARJIS was completing a pilot project that enabled officers to receive information on handheld computers, which was transmitted wirelessly through cellular networks. The accessed information came from several databases that collectively contained the entire region's crime and arrest reports, traffic citations, and incidents, as well as state and county wants and warrants. The fundamental limitations that plague all cellular-based devices caught CSA's attention and resulted in a cooperative effort to harden the communications link between the patrol officer and critical data. The principal goal of the SATCOM development task was to create a proof-of-concept application that would use SATCOM links to augment the current ARJIS handheld wireless (cellular) capability. The successful technical demonstration and the positive support for satellite communications from the law enforcement community showed that this project filled a need-both for improved information sharing and for highly reliable communications systems.

  6. A satellite for demonstration of Panel Extension Satellite (PETSAT)

    Science.gov (United States)

    Sugawara, Yoshiki; Sahara, Hironori; Nakasuka, Shinichi; Greenland, Stephen; Morimoto, Takeshi; Koyama, Kanichi; Kobayashi, Chisato; Kikuchi, Hideaki; Okada, Takanori; Tanaka, Hidenori

    2008-07-01

    This paper presents the current status, configuration, architecture, and key technologies of SOHLA-2, the demonstration mission of the PETSAT (Panel ExTension SATellite) concept. The PETSAT proposal is for a modular satellite consisting of any number of unfolding functional panels. These panels are designed around an open architecture and connected through standardized interfaces. The interfaces between panels incorporate a reliable "plug-in" format, such that when combined, the integrated system takes on the intended satellite function in a redundant and distributed manner. By combining the different panel types in any number and configuration, flexibility to mission requirements is achieved. Some panels for performing basic satellite functions will be available as commercial-off-the-shelf components, and others custom developed dependent on the mission. During launch these panels are stowed in a folded low volume configuration, which is then extended on-orbit, realizing a satellite with a large area for the mounting of solar arrays, mission systems, extensible booms, or any other components. SOHLA-2 is both a concept demonstration and a lightning detection mission in the VHF band. It weighs less than 50 kg and consists of six panels: communication, attitude control, propulsion, mission, experiment and bus function. The bus function panel is based on the successful Cubesat XI developed at the University of Tokyo and this acts as the manager of the technology demonstration aspects for the mission. By basing the architecture upon a proven technology, the reliability of the satellite is increased. It is intended that the satellite be launched in early 2008.

  7. CHINA LAUNCHES 2 SCIENTIFIC EXPERIMENT SATELLITES

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    China placed 2 scientific experiment satellites into preset orbits atop a LM-4B launch vehicle on Sept. 9, 2004. A LM-4B blasted off at 7:14 am from Taiyuan Satellite Launch Center in Shanxi Province. Sources from the Xi'an Satellite Monitor and Control Center said that one satellite,

  8. China Launches First Ever Nano-satellite

    Institute of Scientific and Technical Information of China (English)

    LiuJie

    2004-01-01

    China successfully launched two scientific satellites, including a nano-satellite for the first time, heralding a breakthrough in space technology. A LM-2C rocket carrying Nano-Satellite I (NS-1), which weighs just 25kg and an Experiment Satellite I, weighing 204kg blasted off at 11:59 p.m. on April 18,

  9. Geostationary meteorological satellite systems - An overview

    Science.gov (United States)

    Blersch, Donald J.; Probert, Todd C.

    Past and present geosynchronous meteorological satellites developed in the USA, Europe, Japan, India, and the Soviet Union are reviewed. Particular attention is given to the Applications Technology Satellite Program, GOES and SMS/GOES, METEOSAT, GMS/Himawari, the Indian National Satellite, and a Soviet geostationary meteorological satellite program, GOMS.

  10. Fast Development Of China's Small Satellite Industry

    Institute of Scientific and Technical Information of China (English)

    Sun Hongjin

    2009-01-01

    @@ China Spacesat Co., Ltd of China Academy of Space Technology (CAST) recently said, along with the successful launch of HJ-1A/B for the environment and disaster monitoring and forecasting small satellite constellation and after years of efforts, small satellite development technology has achieved fruitful results, and the development status has been greatly improved.China's small satellite technology has realized a great-leap-forward in development from a single satellite model to series model, from the satellite program to space industry. China has explored a development road for China's small satellite industrialization, and a modern small satellite development base has resulted.

  11. CHINA RETRIEVES 19th RECOVERABLE SATELLITE

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    China on Sept.25 recovered its 19th recoverable sci-tech experimental satellite 27 days after the satellite orbited in space. The satellite, which was launched on Aug.29 from the Jiuquan Satellite Launch Center in Gansu Province, northwest China, touched the ground at 7:55 a.m.on Sept.25. The satellite, atop a Long March 2C carrier rocket, is mainly for

  12. Using Cell Phones From Satellites

    Science.gov (United States)

    Horan, Stephen

    2000-01-01

    During the past several years, an interest has grown in using commercial telecommunications techniques to supply Telemetry and Command (T&C) services. Recently, the National Aeronautics and Space Administration (NASA) Space Operations Management Office (SOMO) has outlined plans to utilize satellite-based telecommunications services to support space operations in space missions over the next several decades. NASA currently obtains the bulk of its telecommunications services for earth-orbiting satellites via the existing government-owned and controlled Space Network (SN) system. This system consists of the constellation of Tracking and Data Relay Satellites (TDRS) in Geostationary Earth Orbit (GEO) and the associated ground terminals and communications intrastructure. This system is valuable and effective for scientific satellites costing over one million dollars. However, for smaller satellites, this system becomes problematic due to the cost of transponders and support infrastructure. The nominal transponders for using the TDRS cannot be obtained for a cost in dollars, and size, weight, or power that the 3 Corner Satellite project can afford. For these types of nanosatellite missions, alternatives that fit the mission cost and satellite profiles are needed. In particular, low-cost access using existing commercial infrastructure would be useful to mission planners. In particular, the ability to obtain low data rate T&C services would be especially valuable. The nanosatellites generally have low T&C requirements and therefore would benefit from using commercial services that could operate in the 2400 bps - 9600 bps range, especially if contact times longer than the 5 - 10 minute ground station passes could be found.

  13. VLBI observations of geosynchronous satellites

    Science.gov (United States)

    Shu, Fengchun; Zhang, Xiuzhong; Zheng, Weimin

    The principle of determining spacecraft angular position with differential VLBI (Very Long Baseline Interferometry) technique is described. The first domestic differential VLBI observations of geosynchronous satellites were performed with participations of Shanghai, Urumqi and Kunming stations. Three strong quasars within angular separation of 15° from target satellites were selected as reference radio sources. The main purpose of such observations is to obtain interferometric fringes of the satellites, and to estimate accuracy of differential VLBI observations. A 2-station FX type correlator at SHAO (Shanghai Astronomical Observatory) was used to do cross-correlations of radio signals in MK3A-C tape format. Strong fringes of the satellites were detected to all stations. The precision of time delay and rate was derived from the correlator output. Based on system errors analysis, we estimated that ΔDOR (Delta Differential One-way Ranging) error was about 41 cm, and ΔDOD (Delta Differential One-way Doppler) error was about 0.148mm/s, which corresponded, respectively, to the position error of 8m and the velocity error of 2.8mm/s for the geosynchronous satellite on the plane of sky.

  14. Space Solar Power: Satellite Concepts

    Science.gov (United States)

    Little, Frank E.

    1999-01-01

    Space Solar Power (SSP) applies broadly to the use of solar power for space related applications. The thrust of the NASA SSP initiative is to develop concepts and demonstrate technology for applying space solar power to NASA missions. Providing power from satellites in space via wireless transmission to a receiving station either on earth, another celestial body or a second satellite is one goal of the SSP initiative. The sandwich design is a satellite design in which the microwave transmitting array is the front face of a thin disk and the back of the disk is populated with solar cells, with the microwave electronics in between. The transmitter remains aimed at the earth in geostationary orbit while a system of mirrors directs sunlight to the photovoltaic cells, regardless of the satellite's orientation to the sun. The primary advantage of the sandwich design is it eliminates the need for a massive and complex electric power management and distribution system for the satellite. However, it requires a complex system for focusing sunlight onto the photovoltaic cells. In addition, positioning the photovoltaic array directly behind the transmitting array power conversion electronics will create a thermal management challenge. This project focused on developing designs and finding emerging technology to meet the challenges of solar tracking, a concentrating mirror system including materials and coatings, improved photovoltaic materials and thermal management.

  15. Commercial applications of satellite oceanography

    Science.gov (United States)

    Montgomery, D. R.

    1981-01-01

    It is shown that in the next decade the oceans' commercial users will require an operational oceanographic satellite system or systems capable of maximizing real-time coverage over all ocean areas. Seasat studies suggest that three spacecraft are required to achieve this. Here, the sensor suite would measure surface winds, wave heights (and spectral energy distribution), ice characteristics, sea-surface temperature, ocean colorimetry, height of the geoid, salinity, and subsurface thermal structure. The importance of oceanographic data being distributed to commercial users within two hours of observation time is stressed. Also emphasized is the importance of creating a responsive oceanographic satellite data archive. An estimate of the potential dollar benefits of such an operational oceanographic satellite system is given.

  16. Gaussian Entanglement Distribution via Satellite

    CERN Document Server

    Hosseinidehaj, Nedasadat

    2014-01-01

    In this work we analyse three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the trade-off between space-based engineering complexity and the rate of ground-station entanglement generation...

  17. The Mexican national satellite system

    Science.gov (United States)

    Sanchez Ruiz, M. E.; Briskman, R. D.

    1983-10-01

    The satellites, tracking, telemetry, command, and monitoring facilities, and the earth station complex for the Mexican national satellite system, Morelos, are described. The spacecraft are intended to provide educational television, rural telephony, data transmission, and business and industrial services. Scheduled for 1985 launch, the satellites will be placed in GEO and use the C and Ku bands with 12 narrow band and six wideband transponders. Spin-stabilized and solar cell powered, the functional mass will be 666 kg, including propellant. The solar panels will provide 940 W of power and 830 W will be available from NiCd batteries during eclipse conditions. The earth station will be located at Iztapalapa, which will have a 12 m antenna, redundant uplink and downlink radios, and command and ranging equipment. Back-up capability will be provided by a station at Tulancingo. Ku band and C band stations are in planning.

  18. Dark Matter tested with satellites

    CERN Document Server

    Combes, F

    2009-01-01

    Recently, the distribution of velocity dispersion as far as 400kpc around red isolated galaxies was derived from statistical studies of satellites in the SDSS (Klypin & Prada 2009). This could help to constrain dark matter models at intermediate scales. We compare the predictions of different DM distributions, LCDM with NFW or cored profiles, and also modified gravity models, with observations. It is shown how the freedom in the various parameters (radial distribution of satellites, velocity anisotropy, external field effect), prevents to disentangle the models, which all can give pretty good fits to the data. In all cases, realistic radial variations of velocity anisotropy are used for the satellites, and a constant stellar-mass to light ratio for the host galaxies.

  19. Satellite Data Transmission (SDT) requirement

    Science.gov (United States)

    Chie, C. M.; White, M.; Lindsey, W. C.

    1984-01-01

    An 85 Mb/s modem/codec to operate in a 34 MHz C-band domestic satellite transponder at a system carrier to noise power ratio of 19.5 dB is discussed. Characteristics of a satellite channel and the approach adopted for the satellite data transmission modem/codec selection are discussed. Measured data and simulation results of the existing 50 Mbps link are compared and used to verify the simulation techniques. Various modulation schemes that were screened for the SDT are discussed and the simulated performance of two prime candidates, the 8 PSK and the SMSK/2 are given. The selection process that leads to the candidate codec techniques are documented and the technology of the modem/codec candidates is assessed. Costs of the modems and codecs are estimated.

  20. Small satellites and their regulation

    CERN Document Server

    Jakhu, Ram S

    2014-01-01

    Since the launch of UoSat-1 of the University of Surrey (United Kingdom) in 1981, small satellites proved regularly to be useful, beneficial, and cost-effective tools. Typical tasks cover education and workforce development, technology demonstration, verification and validation, scientific and engineering research as well as commercial applications. Today the launch masses range over almost three orders of magnitude starting at less than a kilogram up to a few hundred kilograms, with budgets of less than US$ 100.00 and up to millions within very short timeframes of sometimes less than two years. Therefore each category of small satellites provides specific challenges in design, development and operations. Small satellites offer great potentials to gain responsive, low-cost access to space within a short timeframe for institutions, companies, regions and countries beyond the traditional big players in the space arena. For these reasons (particularly the low cost of construction, launch and operation), small (m...

  1. Reinventing the Solar Power Satellite

    Science.gov (United States)

    Landis, Geoffrey A.

    2004-01-01

    The selling price of electrical power varies with time. The economic viability of space solar power is maximum if the power can be sold at peak power rates, instead of baseline rate. Price and demand of electricity was examined from spot-market data from four example markets: New England, New York City, suburban New York, and California. The data was averaged to show the average price and demand for power as a function of time of day and time of year. Demand varies roughly by a factor of two between the early-morning minimum demand, and the afternoon maximum; both the amount of peak power, and the location of the peak, depends significantly on the location and the weather. The demand curves were compared to the availability curves for solar energy and for tracking and non-tracking satellite solar power systems in order to compare the market value of terrestrial and solar electrical power. In part 2, new designs for a space solar power (SSP) system were analyzed to provide electrical power to Earth for economically competitive rates. The approach was to look at innovative power architectures to more practical approaches to space solar power. A significant barrier is the initial investment required before the first power is returned. Three new concepts for solar power satellites were invented and analyzed: a solar power satellite in the Earth-Sun L2 point, a geosynchronous no-moving parts solar power satellite, and a nontracking geosynchronous solar power satellite with integral phased array. The integral-array satellite had several advantages, including an initial investment cost approximately eight times lower than the conventional design.

  2. Natural Satellite Ephemerides at JPL

    Science.gov (United States)

    Jacobson, Robert Arthur; Brozovic, Marina

    2015-08-01

    There are currently 176 known natural planetary satellites in the solar system; 150 are officially recognized by the IAU and 26 have IAU provisional designations. We maintain ephemerides for all of the satellites at NASA's Jet Propulsion Laboratory (JPL) and make them available electronically through the On-Line Solar System Data Service known as Horizons(http://ssd.jpl.nasa.gov/horizons) and in the form of generic Spice Kernels (SPK files) from NASA's Navigation and Ancillary Information Facility (http://naif.jpl.nasa.gov/naif). General satellite information such as physical constants and descriptive orbital elements can be found on the JPL Solar System Dynamics Website (http://ssd.jpl.nasa.gov). JPL's ephemerides directly support planetary spacecraft missions both in navigation and science data analysis. They are also used in general scientific investigations of planetary systems. We produce the ephemerides by fitting numerically integrated orbits to observational data. Our model for the satellite dynamics accounts for the gravitational interactions within a planetary system and the external gravitational perturbations from the Sun and planets. We rely on an extensive data set to determine the parameters in our dynamical models. The majority of the observations are visual, photographic, and CCD astrometry acquired from Earthbased observatories worldwide and the Hubble Space Telescope. Additional observations include optical and photoelectric transits, eclipses, occultations, Earthbased radar ranging, spacecraft imaging,and spacecraft radiometric tracking. The latter data provide information on the planet and satellite gravity fields as well as the satellite position at the times of spacecraft close encounters. In this paper we report on the status of the ephemerides and our plan for future development, specifically that in support of NASA's Juno, Cassini, and New Horizons missions to Jupiter, Saturn, and Pluto, respectively.

  3. Small satellite solar array substrate

    Science.gov (United States)

    Fiore, John N.; Rosanova, Giulio

    1994-01-01

    The SMall EXplorer (SMEX) Fast Auroral SnapshoT (FAST) spacecraft was developed to investigate plasma physics of auroral phenomena at high orbital altitude. The FAST satellite comprises a variety of deployable booms with sensors on the ends, and instruments that protrude from the main body of the spacecraft to obtain the plasma and electromagnetic fields data. This required the plasma disturbance around the satellite to be kept to a minimum. A non deployable, body mounted solar array was implemented. This led to the design of a light weight solar array substrate with a high degree of structural integrity.

  4. Telepresence systems for satellite servicing

    International Nuclear Information System (INIS)

    Telepresence system concepts for satellite servicing are described which are designed to perform complex tasks at remote worksites. Required performance characteristics are developed for specific satellite service functions, and technology issues are identified. Concepts with the operator both nearby and at a great distance from the worksite, with resulting significant time delays, are addressed. A laboratory program established to support the development of such systems is described and preliminary test conclusions are presented. Technology developments required to resolve outstanding technical issues are identified and associated future flight test programs are discussed

  5. Chameleon gravity and satellite geodesy

    CERN Document Server

    Morris, J R

    2014-01-01

    We consider the possibility of the detection of a chameleon effect by an earth orbiting satellite such as LAGEOS, and possible constraints that might be placed on chameleon model parameters. Approximate constraints presented here result from using a simple monopole approximation for the gravitational field of the earth, along with results from the Khoury-Weltman chameleon model, solar system constraints obtained from the Cassini mission, and parameter bounds obtained from the LAGEOS satellite. It is furthermore suggested that a comparison of ground-based and space-based multipole moments of the geopotential could reveal a possible chameleon effect.

  6. Satellite voice broadcast system study, volume 2

    Science.gov (United States)

    Horstein, M.

    1985-01-01

    This study investigates the feasibility of providing Voice of America (VOA) broadcasts by satellite relay, rather than via terrestrial relay stations. Satellite voice broadcast systems are described for three different frequency bands: HF (26 MHz), VHF (68 MHz), and L-band (1.5 GHz). The geographical areas of interest at HF and L-band include all major land masses worldwide with the exception of the U.S., Canada, and Australia. Geostationary satellite configurations are considered for both frequency bands. In addition, a system of subsynchronous, circular satellites with an orbit period of 8 hours is developed for the HF band. VHF broadcasts, which are confined to the Soviet Union, are provied by a system of Molniya satellites. Satellites intended for HF or VHF broadcastinbg are extremely large and heavy. Satellite designs presented here are limited in size and weight to the capability of the STS/Centaur launch vehicle combination. Even so, at HF it would take 47 geostationary satellites or 20 satellites in 8-hour orbits to fully satisfy the voice-channel requirements of the broadcast schedule provided by VOA. On the other hand, three Molniya satellites suffice for the geographically restricted schedule at VHF. At L-band, only four geostationary satellites are needed to meet the requirements of the complete broadcast schedule. Moreover, these satellites are comparable in size and weight to current satellites designed for direct broadcast of video program material.

  7. Electric propulsion for small satellites

    International Nuclear Information System (INIS)

    Propulsion is required for satellite motion in outer space. The displacement of a satellite in space, orbit transfer and its attitude control are the task of space propulsion, which is carried out by rocket engines. Electric propulsion uses electric energy to energize or accelerate the propellant. The electric propulsion, which uses electrical energy to accelerate propellant in the form of plasma, is known as plasma propulsion. Plasma propulsion utilizes the electric energy to first, ionize the propellant and then, deliver energy to the resulting plasma leading to plasma acceleration. Many types of plasma thrusters have been developed over last 50 years. The variety of these devices can be divided into three main categories dependent on the mechanism of acceleration: (i) electrothermal, (ii) electrostatic and (iii) electromagnetic. Recent trends in space exploration associate with the paradigm shift towards small and efficient satellites, or micro- and nano-satellites. A particular example of microthruster considered in this paper is the micro-cathode arc thruster (µCAT). The µCAT is based on vacuum arc discharge. Thrust is produced when the arc discharge erodes some of the cathode at high velocity and is accelerated out the nozzle by a Lorentz force. The thrust amount is controlled by varying the frequency of pulses with demonstrated range to date of 1–50 Hz producing thrust ranging from 1 µN to 0.05 mN. (paper)

  8. Electric propulsion for small satellites

    Science.gov (United States)

    Keidar, Michael; Zhuang, Taisen; Shashurin, Alexey; Teel, George; Chiu, Dereck; Lukas, Joseph; Haque, Samudra; Brieda, Lubos

    2015-01-01

    Propulsion is required for satellite motion in outer space. The displacement of a satellite in space, orbit transfer and its attitude control are the task of space propulsion, which is carried out by rocket engines. Electric propulsion uses electric energy to energize or accelerate the propellant. The electric propulsion, which uses electrical energy to accelerate propellant in the form of plasma, is known as plasma propulsion. Plasma propulsion utilizes the electric energy to first, ionize the propellant and then, deliver energy to the resulting plasma leading to plasma acceleration. Many types of plasma thrusters have been developed over last 50 years. The variety of these devices can be divided into three main categories dependent on the mechanism of acceleration: (i) electrothermal, (ii) electrostatic and (iii) electromagnetic. Recent trends in space exploration associate with the paradigm shift towards small and efficient satellites, or micro- and nano-satellites. A particular example of microthruster considered in this paper is the micro-cathode arc thruster (µCAT). The µCAT is based on vacuum arc discharge. Thrust is produced when the arc discharge erodes some of the cathode at high velocity and is accelerated out the nozzle by a Lorentz force. The thrust amount is controlled by varying the frequency of pulses with demonstrated range to date of 1-50 Hz producing thrust ranging from 1 µN to 0.05 mN.

  9. China Satcom: Innovating Satellite Communication

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China Satellite Communications Group Corporation (China Satcom) is a state-owned large-sized key enterprise formally established on Dec. 19, 2001 according to the general deployment of the State Council on telecommunication system reform. Relying on its complete service system, China Satcom provides various users with specialized and high quality information communication service.

  10. China's Meteorological Satellite Application System

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen

    2008-01-01

    @@ (Continued) Applications In Global Environment And Natural Disaster Monitoring 1) Application in world crop yield estimation China is now one of the few nations in the world that can provide operational service with both GEO and polar-orbit meteorological satellites.

  11. Introductory Course on Satellite Navigation

    Science.gov (United States)

    Giger, Kaspar; Knogl, J. Sebastian

    2012-01-01

    Satellite navigation is widely used for personal navigation and more and more in precise and safety-critical applications. Thus, the subject is suited for attracting the interest of young people in science and engineering. The practical applications allow catching the students' attention for the theoretical background. Educational material on the…

  12. Overview of the meteorological satellite

    Energy Technology Data Exchange (ETDEWEB)

    Kodaira, Nobuhiko

    1988-01-25

    The geostational meteorological satellite (Himawari) GMS-3 is now in activity. The next satellite GMS-4-4 is to be launched in 1989. GMS is a geostational meteorological satellite with rotates at 100 rpm by the spin stabilization system. The spin axis is perpendicular to the orbital plane across the earth. For imaging of the earth, GMS scans the earth from the west to the east, with a visible IR radiator. With the computer recently introduced, the observation can be successively made every 1 hour interval in the normal condition. The cloud-moving image obtained by the successive observation shows the cloud movement more smoothly, as compared with that obtained by conventional observation every 3 hour interval. The main meteorological observation items which can not be achieved by the present meteorological satellite include rainfall and ground atmospheric pressure. TRMM for measuring rainfalls is under co-investigation of U.S.A. and Japan. Measurement of atomospheric pressure has not reached the practical use stage yet. Typical measuring method utilizes the O/sub 2/ absorption wavelength range with a microwave. (6 figs, 2 tabs, 4 refs)

  13. Small satellites for tropical applications

    Science.gov (United States)

    Montpetit, Marie-Jose; Bonn, Ferdinand

    1993-11-01

    A number of mission studies were performed to assess the suitability of small satellite systems for tropical data acquisition. These studies took into account the specifics of the tropical user communities and were focused on remote sensing and resource management issues. The requirements and potential solutions for four application areas are discussed. For monitoring of forest and agricultural vegetation, a small synthetic aperture radar is considered with P, C, or X band imaging, possibly supplemented by a high resolution multispectral imager. The radar would have the capability to monitor below cloud cover which is often found in tropical regions. Optical, microwave, or spectrographic imaging would also be useful in small satellites for disaster monitoring (notably of floods), land management, and air pollution monitoring. A small satellite with data storage and forwarding capability is also envisioned to collect data from dependable, low-power, and low-cost ground sensors via a simple ultrahigh frequency uplink and download the data on a very high frequency downlink. All the small satellites would be launched in low inclination orbits to ensure a number of consecutive passes over the targeted tropical area.

  14. Monitoring Global Temperatures From Satellites

    Science.gov (United States)

    Spencer, Roy W.; Christy, John R.

    1992-01-01

    Report provides evidence that passive microwave radiometry from satellites provides more-precise information on atmospheric temperatures than sparse distribution of thermometers. Accurate temperatures needed for detection of "greenhouse" warming, evaluation of computer models of change in climate, and for understanding important factors in climate system.

  15. MEMOS - Mars Environment Monitoring Satellite

    Science.gov (United States)

    Ott, T.; Barabash, S.; von Schéele, F.; Clacey, E.; Pokrupa, N.

    2007-08-01

    The Swedish Institute of Space Physics (IRF) in cooperation with the Swedish Space Corporation (SSC) has conducted first studies on a Mars Environment Monitoring Satellite (MEMOS). The MEMOS microsatellite (mass budget. The low thrust level enables precise and active nutation damping. Moreover the system offers the possibility of implementing active orbit control or formation flight demonstrations at Mars. Attitude will be determined on-board with an accuracy based on MEMS-technology. TM/TC will be relayed via the parent satellite in the UHF frequency range. Therefore the Electra Lite (ELT) Proximity-1 transceiver will autonomously communicate with the parent satellite at inter-satellite ranges 2 kbit/s. The transceiver also implements a coherent transponding mode for orbit determination through two-way Doppler ranging between the parent satellite and MEMOS. In addition ELT is compatible with a future Martian communication and navigation network pursued by NASA, which could be taken advantage of in the future for relaying data or performing ranging via other satellites part of the network. A system design driver for inter-satellite communication at Mars is the high demand of power. This leads to a disk-shape and thus easy to accommodate spacecraft configuration of MEMOS comprising a single sun-pointing solar array favourable in terms of power and spin stability. Multi-junction solar cells, which currently have an efficiency of ~29% under laboratory conditions are a key factor to keep MEMOS solar array area of ~1.15 m2 small compared to the worst case system power requirements of ~105 W. During eclipse periods high-efficient Li-ion batteries (6 x 20 Wh) will ensure power supply. The spacecraft and payload design will incorporate new technology developments such as autonomous navigation, MicroElectroMechanical Systems MEMS, Micro- Opto-ElectroMechanical Systems MOEMS and new materials to achieve low mass at high performance. Thereby it will profit from Swedish

  16. DIORAMA Model of Satellite Body Orientation

    Energy Technology Data Exchange (ETDEWEB)

    Werley, Kenneth Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-04

    The DIORAMA GPS satellite platform orientation model is described. Satellites need to keep sensors pointed towards the earth and solar panels oriented to face the sun (when not in the earth’s shadow) while they orbit the earth.

  17. Space Environment Deteation of Chinese Meteorological Satellites

    Institute of Scientific and Technical Information of China (English)

    XU Ying; WANG Shijin; ZHU Guangwu; LIANG Jinbao

    2004-01-01

    This paper presents the space environment detection of Chinese geosynchronous and sun-synchronous meteorological satellites and gives a short perspective of space environment observations on board meteorological satellites.

  18. Satellite Tags- Guam/CNMI EEZ

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Satellite tagging was implemented in 2013. Satellite tagging is conducted using a Dan Inject air rifle and deployment arrows designed by Wildlife Computers. Two...

  19. Highly Enhanced Risk Management Emergency Satellite

    DEFF Research Database (Denmark)

    Dalmeir, Michael; Gataullin, Yunir; Indrajit, Agung;

    HERMES (Highly Enhanced Risk Management Emergency Satellite) is potential European satellite mission for global flood management, being implemented by Technical University Munich and European Space Agency. With its main instrument - a reliable and precise Synthetic Aperture Radar (SAR) antenna...

  20. New Equipment Training Center-Satellite Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The ARDEC Satellite Facility is a 24-hour on-site military satellite transmission and downlink capability to Southwest Asia and all other military OCONUS and CONUS...

  1. A new small satellite goes into orbit

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ On 5 November, 2008,a rocket launched the Chuangxin-1(02), a small satellite built by the Shanghai Engineering Center for MicroSatellite under the CAS Shanghai Institute of Microsystem and Information Technology, into its preset orbit.

  2. RFP for the italien satellite AGILE

    DEFF Research Database (Denmark)

    Madsen, Peter Buch; Jørgensen, John Leif; Riis, Troels;

    1999-01-01

    The document descibes the ASC Star Tracker (performance, functionality, requirements etc.) to the Italian satellite AGILE.......The document descibes the ASC Star Tracker (performance, functionality, requirements etc.) to the Italian satellite AGILE....

  3. Sobre os céus e as marés do Pacífico: as observações astronômicas do jesuíta Nicolás Mascardi (Chile, século XVII

    Directory of Open Access Journals (Sweden)

    Eliane Cristina Deckmann Fleck

    2014-12-01

    Full Text Available A atuação da Companhia de Jesus na América espanhola e portuguesa constitui-se em tema de várias investigações e obras, nas quais merece destaque a dedicação de seus religiosos ao ensino e à catequese. Alguns membros da Ordem, no entanto, se dedicaram, também, a observações de fenômenos naturais, da fauna e da flora nativas e, ainda, a aspectos da geografia dos territórios em que atuaram, legando-nos uma série de estudos informados através de cartas, relatórios ou obras. Nosso propósito neste artigo é o de apresentar e analisar os registros que o padre jesuíta italiano Nicolás Mascardi fez de suas observações astronômicas e, em especial, do estudo que realizou sobre as marés do arquipélago de Chiloé durante os anos em que atuou na então Vice-Província Jesuítica do Chile, no século XVII.

  4. Specifics of Small Satellite Propulsion: Part 1

    OpenAIRE

    Zakirov, Vadim; Sweeting, Martin; Erichsen, Peter; Lawrence, Timothy

    2001-01-01

    Small satellite propulsion is a subject of unique constraints and requirements. Based on University of Surrey experience in small satellite building and operation, these features are listed and explained. Available volume is often identified as the most severe constraint for a small satellite with power and cost being the other two major constraints. Mass is often only of secondary importance for small satellites. Propulsion dry mass fraction for a spacecraft grows upon the system scaling-dow...

  5. User Validation of VIIRS Satellite Imagery

    OpenAIRE

    Don Hillger; Tom Kopp; Curtis Seaman; Steven Miller; Dan Lindsey; Eric Stevens; Jeremy Solbrig; William Straka III; Melissa Kreller; Arunas Kuciauskas; Amanda Terborg

    2015-01-01

    Visible/Infrared Imaging Radiometer Suite (VIIRS) Imagery from the Suomi National Polar-orbiting Partnership (S-NPP) satellite is the finest spatial resolution (375 m) multi-spectral imagery of any operational meteorological satellite to date. The Imagery environmental data record (EDR) has been designated as a Key Performance Parameter (KPP) for VIIRS, meaning that its performance is vital to the success of a series of Joint Polar Satellite System (JPSS) satellites that will carry this instr...

  6. Mobility Extension for Broadband Satellite Multimedia

    OpenAIRE

    Hu, Y.Fun; Pillai, Prashant; Berioli, Matteo

    2009-01-01

    This paper presents an extension for Broadband Satellite Multimedia (BSM) to support Mobility Management (MM). To support seamless handovers, mobility related entities are proposed in the Satellite Independent Access Function (SIAF) defined over the SI-SAP interface. This enables the mapping of the mobility related primitives between the higher layer and the satellite dependant lower layers via the Satellite Dependent Access Function (SDAF). The proposed MM architecture incorporates the Media...

  7. Sustained Satellite Missions for Climate Data Records

    Science.gov (United States)

    Halpern, David

    2012-01-01

    Satellite CDRs possess the accuracy, longevity, and stability for sustained moni toring of critical variables to enhance understanding of the global integrated Earth system and predict future conditions. center dot Satellite CDRs are a critical element of a global climate observing system. center dot Satellite CDRs are a difficult challenge and require high - level managerial commitment, extensive intellectual capital, and adequate funding.

  8. Small Satellite Space Environments Effects Test Facility

    OpenAIRE

    Dennison, JR; Hartley, Kent; Montierth Phillipps, Lisa; Johnson, Robert; Dekany, Justin; Dyer, James

    2014-01-01

    A versatile space environments test facility has been designed and built to study the effects on small satellites and system components. Testing for potentially environmental-induced modifications of small satellites is critical to avoid possible deleterious or catastrophic effects over the duration of space missions. This is increasingly more important as small satellite programs have longer mission lifetimes, expand to more hash env...

  9. 14 CFR 141.91 - Satellite bases.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Satellite bases. 141.91 Section 141.91... OTHER CERTIFICATED AGENCIES PILOT SCHOOLS Operating Rules § 141.91 Satellite bases. The holder of a... assistant chief instructor is designated for each satellite base, and that assistant chief instructor...

  10. When does a satellite knot fiber?

    OpenAIRE

    Hirasawa, Mikami; Murasugi, Kunio; Silver, Daniel S.

    2007-01-01

    Necessary and sufficient conditions are given for a satellite knot to be fibered. Any knot $\\tilde k$ embeds in an unknotted solid torus $\\tilde V$ with arbitrary winding number in such a way that no satellite knot with pattern $(\\tilde V, \\tilde k)$ is fibered. In particular, there exist nonfibered satellite knots with fibered pattern and companion knots and nonzero winding number.

  11. China Launches Two Natural Disaster Monitoring Satellites

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ China launched two satellites, HJ-1A and HJ-1B, to monitor the environment and natural disasters at 11:25am on September 6 (Beijing time) from the Taiyuan Satellite Launch Center in Shanxi Province. The two satellites are expected to improve the country's ability in the rapid monitoring of environmental changes and reducing calamities.

  12. Processor Units Reduce Satellite Construction Costs

    Science.gov (United States)

    2014-01-01

    As part of the effort to build the Fast Affordable Science and Technology Satellite (FASTSAT), Marshall Space Flight Center developed a low-cost telemetry unit which is used to facilitate communication between a satellite and its receiving station. Huntsville, Alabama-based Orbital Telemetry Inc. has licensed the NASA technology and is offering to install the cost-cutting units on commercial satellites.

  13. QRM, Packet Satellites and Spread Spectrum

    OpenAIRE

    Cobb, Stewart

    1989-01-01

    Digital messaging satellites designed for general use may attract considerable user interest. High interest will mean heavy interference on the satellite uplink channels, which could make the satellite useless. This paper discusses the characteristics of this interference, and proposes a solution using spread-spectrum technology.

  14. An Overview Of Operational Satellites Built By China: Communications Satellites (Part1)

    Institute of Scientific and Technical Information of China (English)

    Guang Bo

    2008-01-01

    @@ Communications satellite technology has seen great advances since Decemher 1958 when the Americans launched the first experimental communications satellite.Currently, satellite communications account for over 80 percent of the intercontinental communications traffic and 100 percent of international live TV broadcast, while taking part in domestic and regional services. Moreover, the satellite communication service is showing a favorable continuous growth tendency.

  15. Attitude control of a nano satellite

    OpenAIRE

    2010-01-01

    The CubeSTAR satellite is a student satellite project at the University of Oslo. The main mission is to measure the turbulence in the electron plasma using a novel Multi Needle Langmuir Probe system developed at the University of Oslo. In order to get correct measurements, it’s important that the probes are located in the front of the satellite in the orbit velocity direction. In this thesis, the attitude control problem of the CubeSTAR nano-satellite is the main topic. The satellite wil...

  16. Satellite communications network design and analysis

    CERN Document Server

    Jo, Kenneth Y

    2011-01-01

    This authoritative book provides a thorough understanding of the fundamental concepts of satellite communications (SATCOM) network design and performance assessments. You find discussions on a wide class of SATCOM networks using satellites as core components, as well as coverage key applications in the field. This in-depth resource presents a broad range of critical topics, from geosynchronous Earth orbiting (GEO) satellites and direct broadcast satellite systems, to low Earth orbiting (LEO) satellites, radio standards and protocols.This invaluable reference explains the many specific uses of

  17. Satellite television analogue and digital reception techniques

    CERN Document Server

    Benoit, Herve

    1999-01-01

    Satellite television is part of the lives of millions of television viewers worldwide and its influence is set to increase significantly with the launch of digital satellite television services.This comprehensive reference book, written by the author of the highly successful 'Digital Television', provides a technical overview of both analogue and digital satellite TV. Written concisely and thoroughly, it covers all aspects of satellite TV necessary to understand its operation and installation. It also covers the evolution of satellite television, and contains a detailed glossary of tec

  18. Sweeping and shaking dwarf satellites

    CERN Document Server

    Mayer, L; Mayer, Lucio; Wadsley, James

    2003-01-01

    We present the first high-resolution N-Body/SPH simulations that follow the evolution of low surface brightness disk satellites in a primary halo containing both dark matter and a hot gas component. Tidal shocks turn the stellar disk into a spheroid with low $v/\\sigma$ and remove most of the outer dark and baryonic mass. In addition, by weakening the potential well of the dwarf, tides enhance the effect of ram pressure, and the gas is stripped down to radius three times smaller than the stellar component A very low gas/stars ratio results after several Gyr, similarly to what seen in dwarf spheroidal satellites of the Milky Way and M31.

  19. Desert dust satellite retrieval intercomparison

    Directory of Open Access Journals (Sweden)

    E. Carboni

    2012-01-01

    Full Text Available This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify and understand the differences between current algorithms, and hence improve future retrieval algorithms. The satellite instruments considered are AATSR, AIRS, MERIS, MISR, MODIS, OMI, POLDER, and SEVIRI. An interesting aspect is that the different algorithms make use of different instrument characteristics to obtain retrievals over bright surfaces. These include multi-angle approaches (MISR, AATSR, polarisation measurements (POLDER, single-view approaches using solar wavelengths (OMI, MODIS, and the thermal infrared spectral region (SEVIRI, AIRS. Differences between instruments, together with the comparison of different retrieval algorithms applied to measurements from the same instrument, provide a unique insight into the performance and characteristics of the various techniques employed. As well as the intercomparison between different satellite products, the AODs have also been compared to co-located AERONET data. Despite the fact that the agreement between satellite and AERONET AODs is reasonably good for all of the datasets, there are significant differences between them when compared to each other, especially over land. These differences are partially due to differences in the algorithms, such as assumptions about aerosol model and surface properties. However, in this comparison of spatially and temporally averaged data, at least as significant as these differences are sampling issues related to the actual footprint of each instrument on the heterogeneous aerosol field, cloud identification and the quality control flags of each dataset.

  20. Satellite altimetry and ocean dynamics

    OpenAIRE

    Fu, Lee Lueng; Le Traon, Pierre-Yves

    2006-01-01

    This paper provides a summary of recent results derived from satellite altimetry. It is focused on altimetry and ocean dynamics with synergistic use of other remote sensing techniques, in-situ data and integration aspects through data assimilation. Topics include mean ocean circulation and geoid issues, tropical dynamics and large-scale sea level and ocean circulation variability, high-frequency and intraseasonal variability, Rossby waves and mesoscale variability. To cite this article: L.L. ...

  1. Tourism Satellite Account for India

    OpenAIRE

    Rajesh Shukla

    2006-01-01

    With the growing recognition of tourism as a source of employment generating growth in the country, improved understanding of what tourism is, its role in the economy and its relationship to other parts of the economy is important. The Tourism Satellite Account (TSA) is a new framework recently adopted by the United Nations Statistical Commission that provides an important platform towards forging improved understanding of the structure and role of tourism in the economy. Estimates using the ...

  2. Laser Payloads on Small Satellites

    OpenAIRE

    Lingvay, L.S.; Bowman, A.P.; Wallace, A. S.

    1990-01-01

    Laser payloads on satellites have the ability to enhance our communications capabilities and information gathering power from space. Implementation of lasers to Lightsats provides one method to assess the effectiveness of these technologies at reduced risk. This paper will focus on the main applications of lasers in space and how laser systems may be adapted to the Lightsat environment. This will include a discussion of the different types of lasers, which types are suitable for space based p...

  3. Marine Corps Tactical Satellite Communications

    OpenAIRE

    Daniel, Walter; Rivas, Gavino; Bruninga, Robert

    1992-01-01

    A tactical satellite communications exercise using the DARPA Microsats was conducted by Naval Academy personnel at the Quantico Marine Corps Base in Virginia. Midshipmen used a military UHF radio, a modified amateur radio transmitter, and scanner receivers while a station in Annapolis communicated with them. Voice communications were clear and understandable even when the tactical teams were in the woods. Amateur radio operators and scanner enthusiasts around the eastern half of the United St...

  4. Weather Satellite Pictures and How to Obtain Them.

    Science.gov (United States)

    Petit, Noel J.; Johnson, Philip

    1982-01-01

    An introduction to satellite meteorology is presented to promote use of live weather satellite photographs in the classroom. Topics addressed include weather satellites, how they work, earth emissions, satellite photography, satellite image analysis, obtaining satellite pictures, and future considerations. Includes sources for materials to…

  5. The Giant Planet Satellite Exospheres

    Science.gov (United States)

    McGrath, Melissa A.

    2014-01-01

    Exospheres are relatively common in the outer solar system among the moons of the gas giant planets. They span the range from very tenuous, surface-bounded exospheres (e.g., Rhea, Dione) to quite robust exospheres with exobase above the surface (e.g., lo, Triton), and include many intermediate cases (e.g., Europa, Ganymede, Enceladus). The exospheres of these moons exhibit an interesting variety of sources, from surface sputtering, to frost sublimation, to active plumes, and also well illustrate another common characteristic of the outer planet satellite exospheres, namely, that the primary species often exists both as a gas in atmosphere, and a condensate (frost or ice) on the surface. As described by Yelle et al. (1995) for Triton, "The interchange of matter between gas and solid phases on these bodies has profound effects on the physical state of the surface and the structure of the atmosphere." A brief overview of the exospheres of the outer planet satellites will be presented, including an inter-comparison of these satellites exospheres with each other, and with the exospheres of the Moon and Mercury.

  6. Jupiter and Its Galilean Satellites

    Science.gov (United States)

    McGrath, Melissa A.

    2012-01-01

    Jupiter is one of the two most studied planets other than Earth in our Solar System. It is the largest, fastest rotating, has the strongest magnetic field, and an incredibly diverse set of satellites, most prominent of which are the four Galilean satellites discovered in 1610. Io, Europa, Ganymede and Callisto encompass some of the most bizarre environments known in the solar system, from Io, the most volcanically active and perhaps the most inhospitable body known, to Europa, currently thought to be the most likely extraterrestrial abode for habitability, to Ganymede, which is larger than Mercury, and Callisto, which has the oldest surface known in the solar system with the widest array of crater morphologies known. One of the premier areas of scientific return in solar system research in the past 15 years, due in large part to the Galileo mission and observations by the Hubble Space Telescope, has been a remarkable increase in our knowledge about these satellites. Discoveries have been made of tenuous molecular oxygen atmospheres on Europa and Ganymede, a magnetic field and accompanying auroral emissions at the poles of Ganymede, and of ozone and sulfur dioxide embedded in the surfaces of Europa, Ganymede and Callisto. Io's unusual sulfur dioxide atmosphere, including its volcanic plumes and strong electrodynamic interaction with magnetospheric plasma, has finally been quantitatively characterized. This talk will present highlights from the recent discoveries and advances in our understanding of these fascinating objects.

  7. Satellite-based laser windsounder

    International Nuclear Information System (INIS)

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project''s primary objective is to determine the technical feasibility of using satellite-based laser wind sensing systems for detailed study of winds, aerosols, and particulates around and downstream of suspected proliferation facilities. Extensive interactions with the relevant operational organization resulted in enthusiastic support and useful guidance with respect to measurement requirements and priorities. Four candidate wind sensing techniques were evaluated, and the incoherent Doppler technique was selected. A small satellite concept design study was completed to identify the technical issues inherent in a proof-of-concept small satellite mission. Use of a Mach-Zehnder interferometer instead of a Fabry-Perot would significantly simplify the optical train and could reduce weight, and possibly power, requirements with no loss of performance. A breadboard Mach-Zehnder interferometer-based system has been built to verify these predictions. Detailed plans were made for resolving other issues through construction and testing of a ground-based lidar system in collaboration with the University of Wisconsin, and through numerical lidar wind data assimilation studies

  8. Detection and surveillance by satellite

    International Nuclear Information System (INIS)

    In parallel with the conventional methods used for detecting nuclear explosions and revealing signs of proliferation and, as a consequence, the monitoring of human activities. Among the main advantages of satellites is their ability to carry out non-intrusive observations of any part of the Earth's surface at all times, while remaining in full compliance with legal requirements. Satellite-based detection is based on the electromagnetic pulse (EMP) and various optical effects. The modification of signals as they traverse the atmosphere and ionosphere should also be taken into account, but such changes in no way hinder the detection. Ultra-high frequencies are the most suitable for detection since they are less affected by the ionosphere. Signals propagated in this way are characteristic and can be distinguished from those due to lightning storms. However, some important questions arise because of the recent discovery of a new type of lightning which propagates from the tops of clouds towards the ionosphere. The electromagnetic signal in some respects is similar to that produced by an explosion. Site surveillance depends on the analysis and processing of satellite imagery such as obtained by SPOT, Landsat or ERSI. More precise measurements obtained by interferometry (ERSI) enable the observation of small-amplitude strains with can lead to the discrimination of natural seismic events from nuclear explosions. (authors)

  9. Satellite-based laser windsounder

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, J.F.; Czuchlewski, S.J.; Quick, C.R. [and others

    1997-08-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project`s primary objective is to determine the technical feasibility of using satellite-based laser wind sensing systems for detailed study of winds, aerosols, and particulates around and downstream of suspected proliferation facilities. Extensive interactions with the relevant operational organization resulted in enthusiastic support and useful guidance with respect to measurement requirements and priorities. Four candidate wind sensing techniques were evaluated, and the incoherent Doppler technique was selected. A small satellite concept design study was completed to identify the technical issues inherent in a proof-of-concept small satellite mission. Use of a Mach-Zehnder interferometer instead of a Fabry-Perot would significantly simplify the optical train and could reduce weight, and possibly power, requirements with no loss of performance. A breadboard Mach-Zehnder interferometer-based system has been built to verify these predictions. Detailed plans were made for resolving other issues through construction and testing of a ground-based lidar system in collaboration with the University of Wisconsin, and through numerical lidar wind data assimilation studies.

  10. Satellite Attitude Control System Simulator

    Directory of Open Access Journals (Sweden)

    G.T. Conti

    2008-01-01

    Full Text Available Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS, using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.

  11. Configurable software for satellite graphics

    Energy Technology Data Exchange (ETDEWEB)

    Hartzman, P D

    1977-12-01

    An important goal in interactive computer graphics is to provide users with both quick system responses for basic graphics functions and enough computing power for complex calculations. One solution is to have a distributed graphics system in which a minicomputer and a powerful large computer share the work. The most versatile type of distributed system is an intelligent satellite system in which the minicomputer is programmable by the application user and can do most of the work while the large remote machine is used for difficult computations. At New York University, the hardware was configured from available equipment. The level of system intelligence resulted almost completely from software development. Unlike previous work with intelligent satellites, the resulting system had system control centered in the satellite. It also had the ability to reconfigure software during realtime operation. The design of the system was done at a very high level using set theoretic language. The specification clearly illustrated processor boundaries and interfaces. The high-level specification also produced a compact, machine-independent virtual graphics data structure for picture representation. The software was written in a systems implementation language; thus, only one set of programs was needed for both machines. A user can program both machines in a single language. Tests of the system with an application program indicate that is has very high potential. A major result of this work is the demonstration that a gigantic investment in new hardware is not necessary for computing facilities interested in graphics.

  12. Binning of satellite magnetic anomalies

    Science.gov (United States)

    Goyal, H. K.; Vonfrese, R. R. B.; Hinze, W. J.

    1985-01-01

    Crustal magnetic anomaly signals over satellite orbits were simulated to investigate numerical averaging as an anomaly estimator. Averaging as an anomaly estimator involves significant problems concerning spatial and amplitude smoothing of the satellite magnetic observations. The results of simulations suggest that the error of numerical averaging constitutes a small and relatively minor component of the total error-budget of higher orbital anomaly estimates, whereas for lower orbital estimates numerical averaging error increases substantially. As an alternative to numerical averaging, least-squares collocation was investigated and observed to produce substantially more accurate anomaly estimates, particularly as the orbital elevation of prediction was decreased towards the crustal sources. In contrast to averaging, collocation is a significantly more resource-intensive procedure to apply because of the practical, but surmountable problems related to establishing and inverting the covariance matrix for accurate anomaly prediction. However, collocation may be much more effectively used to exploit the anomaly details contained in the lower orbital satellite magnetic data for geologic analysis.

  13. Satellite remote sensing of vegetation

    Science.gov (United States)

    Mahr, Tobias; Peper, Eva; Schubert, Alexander; Warnach, Simon; Pöhler, Denis; Horbanski, Martin; Beirle, Steffen; Mies, Kornelia; Platt, Ulrich; Wagner, Thomas

    2013-04-01

    DOAS (Differential Optical Absorption Spectroscopy) allows to determine the concentration of trace gases based on their specific absorptions cross-sections along a light path. Since 1995, this principle is employed successfully on satellite-based instruments like GOME, GOME-2 and SCIAMACHY for the global measurement of stratospheric and tropospheric trace gases like ozone and nitrogen oxides. Usually, spectral signatures from the ground, where a big part of the sunlight is reflected, are neglected in the evaluation. This can lead to errors in the trace gas determination. However, these structures offer the opportunity to identify surface properties of the earth and different types of vegetation. To analyse spectral reflectance properties, high resolved reflection spectra (FWHM 0.29 nm) from 95 plants were measured between 350 and 1050 nm. They can serve as a basis for the analysis of satellite data. Including different vegetation reference spectra, it is possible to determine groups of plants with similar optical properties. This allows to derive global maps of the spatio-temporal variation of plant distribution by satellite remote sensing. We present first results of this technique based on SCIAMACHY observations.

  14. Discs of Satellites: the new dwarf spheroidals

    CERN Document Server

    Metz, Manuel; Jerjen, Helmut

    2009-01-01

    The spatial distributions of the most recently discovered ultra faint dwarf satellites around the Milky Way and the Andromeda galaxy are compared to the previously reported discs-of-satellites (DoS) of their host galaxies. In our investigation we pay special attention to the selection bias introduced due to the limited sky coverage of SDSS. We find that the new Milky Way satellite galaxies follow closely the DoS defined by the more luminous dwarfs, thereby further emphasizing the statistical significance of this feature in the Galactic halo. We also notice a deficit of satellite galaxies with Galactocentric distances larger than 100 kpc that are away from the disc-of-satellites of the Milky Way. In the case of Andromeda, we obtain similar results, naturally complementing our previous finding and strengthening the notion that the discs-of-satellites are optical manifestations of a phase-space correlation of satellite galaxies.

  15. An Algorithm of Inter Satellite Two-Way Time Transfer Based on Mobile Satellite

    Directory of Open Access Journals (Sweden)

    Feijiang Huang

    2013-03-01

    Full Text Available Two-way time transfer is one of the most accurate time synchronization methods applied to spacecrafts and ground stations to carry out time transfer. As this method doesn’t require the knowledge of locations of two satellites in advance and it offsets the negative influence of transmission path and other additional delays, this method has boosted the time synchronization accuracy. However, in the process of time synchronization, this method demands that the aircrafts, who conduct time synchronization, could be relatively static. So it is mainly used in GEO satellites for satellite-ground two-way time transfer. Based on the establishment of mobile satellite mutual visual model, the simulation of satellite mutual visual time on mobile satellite, including IGSO (Inclined Geo Synchronous Orbit satellite and MEO (Medium Earth Orbit satellite, has been conducted. The visual time and the variation range of IGSO-MEO link distance have been gained. The characteristics of the propagation delay of two-way time transfer signals between IGSO satellite and MEO satellite varying with inter satellite range were analyzed and the rule of inter satellite clock offset varying with inter satellite range obtained with this algorithm was deduced. This study presents a inter satellite dynamic two-way time transfer algorithm based on mobile satellite. The high-accuracy inter satellite clock offset is solved through the combination of inter satellite pseudo-range polynomial fitting and clock-offset polynomial fitting. Simulation results showed that with the algorithm the inter satellite time transfer error can be controlled within 1ns. The algorithm can be used high-accuracy time transfer between mobile satellites.

  16. Prediction of GNSS satellite clocks

    International Nuclear Information System (INIS)

    This thesis deals with the characterisation and prediction of GNSS-satellite-clocks. A prerequisite to develop powerful algorithms for the prediction of clock-corrections is the thorough study of the behaviour of the different clock-types of the satellites. In this context the predicted part of the IGU-clock-corrections provided by the Analysis Centers (ACs) of the IGS was compared to the IGS-Rapid-clock solutions to determine reasonable estimates of the quality of already existing well performing predictions. For the shortest investigated interval (three hours) all ACs obtain almost the same accuracy of 0,1 to 0,4 ns. For longer intervals the individual predictions results start to diverge. Thus, for a 12-hours- interval the differences range from nearly 10 ns (GFZ, CODE) until up to some 'tens of ns'. Based on the estimated clock corrections provided via the IGS Rapid products a simple quadratic polynomial turns out to be sufficient to describe the time series of Rubidium-clocks. On the other hand Cesium-clocks show a periodical behaviour (revolution period) with an amplitude of up to 6 ns. A clear correlation between these amplitudes and the Sun elevation angle above the orbital planes can be demonstrated. The variability of the amplitudes is supposed to be caused by temperature-variations affecting the oscillator. To account for this periodical behaviour a quadratic polynomial with an additional sinus-term was finally chosen as prediction model both for the Cesium as well as for the Rubidium clocks. The three polynomial-parameters as well as amplitude and phase shift of the periodic term are estimated within a least-square-adjustment by means of program GNSS-VC/static. Input-data are time series of the observed part of the IGU clock corrections. With the estimated parameters clock-corrections are predicted for various durations. The mean error of the prediction of Rubidium-clock-corrections for an interval of six hours reaches up to 1,5 ns. For the 12-hours

  17. Satellite-Based Sunshine Duration for Europe

    Directory of Open Access Journals (Sweden)

    Bodo Ahrens

    2013-06-01

    Full Text Available In this study, two different methods were applied to derive daily and monthly sunshine duration based on high-resolution satellite products provided by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT Satellite Application Facility on Climate Monitoring using data from Meteosat Second Generation (MSG SEVIRI (Spinning Enhanced Visible and Infrared Imager. The satellite products were either hourly cloud type or hourly surface incoming direct radiation. The satellite sunshine duration estimates were not found to be significantly different using the native 15-minute temporal resolution of SEVIRI. The satellite-based sunshine duration products give additional spatial information over the European continent compared with equivalent in situ-based products. An evaluation of the satellite sunshine duration by product intercomparison and against station measurements was carried out to determine their accuracy. The satellite data were found to be within ±1 h/day compared to high-quality Baseline Surface Radiation Network or surface synoptic observations (SYNOP station measurements. The satellite-based products differ more over the oceans than over land, mainly because of the treatment of fractional clouds in the cloud type-based sunshine duration product. This paper presents the methods used to derive the satellite sunshine duration products and the performance of the different retrievals. The main benefits and disadvantages compared to station-based products are also discussed.

  18. German telecommunications satellite (Deutscher fernmelde satellit) (DFS-1 and -2)

    Science.gov (United States)

    Hiendlmeier, G.; Schmeller, H.

    1991-01-01

    The German Telecommunications Satellite (DFS) Program is to provide telecommunications service for high data rate transmission of text and video data to the Federal Republic of Germany within the 11-14 GHz and 20-30 GHz bands. The space segment of this program is composed of three satellites, DFS-1, DFS-2, and DFS-3, which will be located at 23.5 degrees E longitude of the geostationary orbit. The DFS will be launched from the Center Spatial Guyanis in French Giana on an Ariane launch vehicle. The mission follows the typical injection sequence: parking orbit, transfer orbit, and earth orbit. Attitude maneuvers will be performed to orient the spacecraft prior to Apogee Kick Motor (AKM) firing. After AKM firing, drift phase orbital and attitude maneuvers will be performed to place the spacecraft in its final geostationary position. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. Information is presented in tabular form for the following areas: DSN support, compatibility testing, frequency assignments, telemetry, command, and tracking support responsibilities.

  19. Solar power satellite cost estimate

    Science.gov (United States)

    Harron, R. J.; Wadle, R. C.

    1981-01-01

    The solar power configuration costed is the 5 GW silicon solar cell reference system. The subsystems identified by work breakdown structure elements to the lowest level for which cost information was generated. This breakdown divides into five sections: the satellite, construction, transportation, the ground receiving station and maintenance. For each work breakdown structure element, a definition, design description and cost estimate were included. An effort was made to include for each element a reference that more thoroughly describes the element and the method of costing used. All costs are in 1977 dollars.

  20. NOAA's future GOES satellite program

    Science.gov (United States)

    Howard, Edward; Heymann, Roger; Dittberner, Gerald J.; Kirkner, Steven

    1996-10-01

    Future weather satellites for NOAA at geosynchronous orbit may be smaller, less costly, and developed by a different process than is currently done. This path is sometimes called the 'smaller, cheaper and faster' process being pursued by NASA. We believe in the future there will be less money, a focus on using the right technology and the desire to get the most value for the resources invested in space missions. In this paper we give an update on our progress to define future GOES. It will include our efforts to trade on user requirement early, to use evolutionary technology, and to consider new cost reduction and program management techniques.

  1. Satellite spectra of heliumlike nickel

    International Nuclear Information System (INIS)

    Spectra of heliumlike nickel, NiXXVII, have been observed from Tokamak Fusion Test Reactor (TFTR) plasmas with a high resolution crystal spectrometer. The experimental arrangement permits simultaneous observation of the heliumlike resonance line, the intercombination and forbidden lines, and all the associated satellites due to transitions 1s2nl - 1s2l'nl'' with N ≥ 2. Relative wavelengths and line intensities can thus be determined very accurately. The observed spectral data are in good agreement with results from the present Hartree-Fock-Slater atomic model calculations and predictions from the Z-expansion method

  2. Bringing satellite winds to hub-height

    DEFF Research Database (Denmark)

    Badger, Merete; Pena Diaz, Alfredo; Bredesen, Rolv Erlend; Berge, Erik; Hahmann, Andrea N.; Badger, Jake; Karagali, Ioanna; Hasager, Charlotte Bay; Mikkelsen, Torben

    2012-01-01

    Satellite observations of the ocean surface can provide detailed information about the spatial wind variability over large areas. This is very valuable for the mapping of wind resources offshore where other measurements are costly and sparse. Satellite sensors operating at microwave frequencies...... measure the amount of radar backscatter from the sea surface, which is a function of the instant wind speed, wind direction, and satellite viewing geometry. A major limitation related to wind retrievals from satellite observations is that existing empirical model functions relate the radar backscatter to...... wind speed at the height 10 m only. The extrapolation of satellite wind fields to higher heights, which are more relevant for wind energy, remains a challenge which cannot be addressed by means of satellite data alone. As part of the EU-NORSEWInD project (2008-12), a hybrid method has been developed...

  3. SATELLITE FORMATION from ancient massive rings

    Science.gov (United States)

    Crida, Aurélien; Charnoz, Sébastien

    2013-07-01

    When a planetary tidal disk - like Saturn's rings - spreads beyond the Roche radius (inside which planetary tides prevent aggregation), satellites form and migrate away. Here, we show that most regular satellites in the solar system probably formed in this way. According to our analytical model, when the spreading is slow, a retinue of satellites appear with masses increasing with distance to the Roche radius, in excellent agreement with Saturn's, Uranus', and Neptune's satellite systems. This suggests that Uranus and Neptune used to have massive rings that disappeared to give birth to most of their regular satellites. In contrast, when the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth. This conceptually bridges the gap between terrestrial and giant planet systems. (Ref: Crida & Charnoz 2012, Science, 338, 1196-1199)

  4. Kagawa Satellite “STARS” in Shikoku

    Science.gov (United States)

    Nohmi, Masahiro; Yamamoto, Takeshi; Andatsu, Akira; Takagi, Yohei; Nishikawa, Yusuke; Kaneko, Takashi; Kunitom, Daisuke

    The Space Tethered Autonomous Robotic Satellite (STARS) is being developed in Kagawa University, and it will be launched by the H-IIA rocket by Japan Aerospace Exploration Agency (JAXA) in summer 2008. STARS is the first satellite developed in Shikoku, and its specific characteristics are: (i) mother and daughter satellites, which have basic satellite system respectively, and those are launched at the same time; (ii) large space system more than 5m by extending tether; (iii) robotic system, the daughter satellite controls its arm link and the mother satellite controls tether extension. Development of STARS in Kagawa University demonstrates space technology in local community, which has been considered to be a national project. Also, it promotes popularization, enlightenment, and understanding of space technology in local area of the Kagawa prefecture and around it.

  5. An introduction to optimal satellite range scheduling

    CERN Document Server

    Vázquez Álvarez, Antonio José

    2015-01-01

    The satellite range scheduling (SRS) problem, an important operations research problem in the aerospace industry consisting of allocating tasks among satellites and Earth-bound objects, is examined in this book. SRS principles and solutions are applicable to many areas, including: Satellite communications, where tasks are communication intervals between sets of satellites and ground stations Earth observation, where tasks are observations of spots on the Earth by satellites Sensor scheduling, where tasks are observations of satellites by sensors on the Earth. This self-contained monograph begins with a structured compendium of the problem and moves on to explain the optimal approach to the solution, which includes aspects from graph theory, set theory, game theory and belief networks. This book is accessible to students, professionals and researchers in a variety of fields, including: operations research, optimization, scheduling theory, dynamic programming and game theory. Taking account of the distributed, ...

  6. The lopsided distribution of satellite galaxies

    CERN Document Server

    Libeskind, Noam I; Tempel, Elmo; Ibata, Rodrigo

    2016-01-01

    The distribution of smaller satellite galaxies around large central galaxies has attracted attention because peculiar spatial and kinematic configurations have been detected in some systems. A particularly striking example of such behavior is seen in the satellite system of the Andromeda galaxy, where around 80\\% are on the nearside of that galaxy, facing the Milky Way. Motivated by this departure from anisotropy, we examined the spatial distribution of satellites around pairs of galaxies in the SDSS. By stacking tens of thousands of satellites around galaxy pairs we found that satellites tend to bulge towards the other central galaxy, preferably occupying the space between the pair, rather than being spherically or axis-symmetrically distributed around each host. The bulging is a function of the opening angle examined and is fairly strong -- there are up to $\\sim$10\\% more satellites in the space between the pair, than expected from uniform. Consequently, it is a statistically very strong signal, being incon...

  7. Satellite information for wind energy applications

    OpenAIRE

    Nielsen, M.; Astrup, Poul; Hasager, Charlotte Bay; R. J. Barthelmie; S. C. Pryor

    2004-01-01

    An introduction to satellite information relevant for wind energy applications is given. It includes digital elevation model (DEM) data based on satellite observations. The Shuttle Radar Topography Mission (SRTM) is useful for regional scale wind resourcestudies. Comparison results from complex terrain in Spain and flat terrain in Denmark are found to be acceptable for both sites. Also land cover type information can be retrieved from satellite observations. Land cover type maps have to be co...

  8. Tethered satellite system dynamics and control

    Science.gov (United States)

    Musetti, B.; Cibrario, B.; Bussolino, L.; Bodley, C. S.; Flanders, H. A.; Mowery, D. K.; Tomlin, D. D.

    1990-01-01

    The first tethered satellite system, scheduled for launch in May 1991, is reviewed. The system dynamics, dynamics control, and dynamics simulations are discussed. Particular attention is given to in-plane and out-of-plane librations; tether oscillation modes; orbiter and sub-satellite dynamics; deployer control system; the sub-satellite attitude measurement and control system; the Aeritalia Dynamics Model; the Martin-Marietta and NASA-MSFC Dynamics Model; and simulation results.

  9. SaVi: satellite constellation visualization

    CERN Document Server

    Wood, Lloyd

    2012-01-01

    SaVi, a program for visualizing satellite orbits, movement, and coverage, is maintained at the University of Surrey. This tool has been used for research in academic papers, and by industry companies designing and intending to deploy satellite constellations. It has also proven useful for demonstrating aspects of satellite constellations and their geometry, coverage and movement for educational and teaching purposes. SaVi is introduced and described briefly here.

  10. MICROSAT: A New, Small Satellite Bus Concept

    OpenAIRE

    Duncan, Courtney

    1989-01-01

    The Radio Amateur Satellite Corporation of North America (AMSAT-NA) is pioneering a new, small satellite bus concept known as "Microsat." The product is roughly a nine inch cube, exclusive of antennas, with five sub-assemblies. Four are standard: radio transmitter(s), radio receiver(s), power system, and onboard computer. The fifth module is reserved for payload or special application hardware. Design goals dictate that the cost of the satellites and the cost and complexity of ground terminal...

  11. Global navigation satellite systems and their applications

    CERN Document Server

    Madry, Scott

    2015-01-01

    Dr. Madry, one of the world's leading experts in the field, provides in a condensed form a quick yet comprehensive overview of satellite navigation. This book concisely addresses the latest technology, the applications, the regulatory issues, and the strategic implications of satellite navigation systems. This assesses the strengths and weaknesses of satellite navigation networks and review of all the various national systems now being deployed and the motivation behind the proliferation of these systems.

  12. A SEARCH FOR SATELLITES AROUND CERES

    International Nuclear Information System (INIS)

    We conducted a satellite search around the dwarf planet 1 Ceres using Hubble Space Telescope and ground-based Palomar data. No candidate objects were found orbiting Ceres in its entire stability region down to ∼500 km from the surface of Ceres. Assuming a satellite would have the same albedo as Ceres, which has a visual geometric albedo of 0.07-0.10, our detection limit is sensitive to satellites larger than 1-2 km in diameter.

  13. Satellite Sanitary Systems in Kampala, Uganda

    OpenAIRE

    Letema, S.; Van Vliet, B.; Van Lier, J.B.

    2011-01-01

    Satellite sewage collection and treatment systems have been independently developed and managed in East African cities outside the centrally planned and sewered areas. A satellite approach is a promising provisioning option parallel to public sewerage for middle- and high-income residential areas, endowed institutions, and government facilities. Although the studied satellite systems offer localized solutions that fit the situation of Kampala, better treatment and management arrangements are ...

  14. Identifying true satellites of the Magellanic Clouds

    OpenAIRE

    Sales, Laura V.; Navarro, Julio F.; Kallivayalil, Nitya; Frenk, Carlos S.

    2016-01-01

    The hierarchical nature of LCDM suggests that the Magellanic Clouds must have been surrounded by a number of satellites before their infall into the Milky Way. Many of those satellites should still be in close proximity to the Clouds, but some could have dispersed ahead/behind the Clouds along their Galactic orbit. Either way, prior association with the Clouds results in strong restrictions on the present-day positions and velocities of candidate Magellanic satellites: they must lie close to ...

  15. Alignments between galaxies, satellite systems and haloes

    OpenAIRE

    Shao, Shi; Cautun, Marius; Frenk, Carlos S.; Gao, Liang; Crain, Robert A.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-01-01

    The spatial distribution of the satellite populations of the Milky Way and Andromeda are puzzling in that they are nearly perpendicular to the disks of their central galaxies. To understand the origin of such configurations we study the alignment of the central galaxy, satellite system and dark matter halo in the largest of the "Evolution and Assembly of GaLaxies and their Environments" (EAGLE) simulation. We find that centrals and their satellite systems tend to be well aligned with their ha...

  16. Pakistan National Student Satellite Program (PNSSP)

    OpenAIRE

    Alvi, Bilal Ahmad

    2013-01-01

    Micro-satellite development at University environment provides hands-on experience of building a satellite from design through launch and orbit operations for students in a cost effective way. Since multi-disciplinary efforts are required for satellite program are normally available in Universities therefore this kind of projects coupled with team building would provide valuable contribution to aerospace field. It would not only involve traini...

  17. Satellite radiation observations and climate theory

    Science.gov (United States)

    Ohring, G.; Gruber, A.

    1983-01-01

    The representative applications of satellite observations of the earth radiation budget in climate studies are discussed. Consideration is given to the use of satellite observational data for validating numerical estimates of the sensitivity of longwave radiation, surface temperature, and cloud amount to changes in the radiation budget. Particular emphasis is given to the application of satellite observations to the validation of temperature estimates obtained from the NOAA Seasonal Hemispheric Zonal Average Model (SZHAM).

  18. Field Command of a Tactical Satellite System

    OpenAIRE

    Turner, Ron; Hopkins, Stephen

    1990-01-01

    One way to ensure tactical satellite systems remain fully responsive to a field commander's needs would be to place all command and control aspects of the system under direct field control. This paper presents the results of a study to evaluate the feasibility of field command of a notional tactical imaging satellite system. The study indicates that such a system is feasible. A satellite constellation can be designed to provide the field commander with significant, timely, tactical data. The ...

  19. Satellite Remote Sensing in Seismology. A Review

    OpenAIRE

    Andrew A. Tronin

    2009-01-01

    A wide range of satellite methods is applied now in seismology. The first applications of satellite data for earthquake exploration were initiated in the ‘70s, when active faults were mapped on satellite images. It was a pure and simple extrapolation of airphoto geological interpretation methods into space. The modern embodiment of this method is alignment analysis. Time series of alignments on the Earth's surface are investigated before and after the earthquake. A further application of sate...

  20. Towards generic satellite payloads: software radio

    OpenAIRE

    Morlet, Catherine; Boucheret, Marie-Laure; Calmettes, Vincent; Paillassa, Béatrice; Pérennou, Tanguy

    2003-01-01

    Satellite payloads are becoming much more complex with the evolution towards multimedia applications. Moreover satellite lifetime increases while standard and services evolve faster, necessitating a hardware platform that can evolves for not developing new systems on each change. The same problem occurs in terrestrial systems like mobile networks and a foreseen solution is the software defined radio technology. In this paper we describe a way of introducing this concept at satellite level to ...

  1. Regulation of satellite cell function in sarcopenia

    OpenAIRE

    Alway, Stephen E.; Myers, Matthew J.; Mohamed, Junaith S.

    2014-01-01

    The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell) function that is impacted by the environment (niche) of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse or rehabilitation in sarcopenic muscles. Nutritional intervention provides...

  2. Regulation of Satellite Cell Function in Sarcopenia

    OpenAIRE

    Alway, Stephen E.; Myers, Matthew J.; Mohamed, Junaith S.

    2014-01-01

    The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell) function that is impacted by the environment (niche) of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse, or rehabilitation in sarcopenic muscles. Nutritional intervention provide...

  3. Some Mathematical Problems of Satellite Networks

    Science.gov (United States)

    Lo, Martin

    1995-01-01

    Economic forces and technology development have made low-earth-orbit satellite constellations extremely attractive to the emergent personal communications industry. These constellations range from 2 to nearly 1000 satellites. Even though none of the constellations are as yet completely deployed, design on second generation constellations have already begun. The satellite coverage and network links provide some interesting mathematical problems. We examine some of the geometric and combinatorial problems associated with these networks.

  4. Star Tracker Cost Reduction for Small Satellites

    OpenAIRE

    Delabie, Tjorven; DE SCHUTTER, JORIS; Vandenbussche, Bart

    2014-01-01

    In recent years, the great potential of small satellites has become ever clearer and small satellites are selected to perform increasingly complex missions. With this rise in mission complexity, the requirements on the Attitude Determination and Control System of the satellite increase as well. Of all the attitude determination sensors, the star tracker is by far the most accurate one. The accuracy of this sensor is in the order of arc seconds. The disadvantages of this sensor are that it...

  5. Formation and evolution of Pluto's small satellites

    OpenAIRE

    Walsh, Kevin J.; Levison, Harold F.

    2015-01-01

    Pluto's system of 5 known satellites are in a puzzling orbital configuration. Each of the four small satellites are on low-eccentricity and low-inclination orbits situated near a mean motion resonance with the largest satellite Charon. The Pluto-Charon binary likely formed as a result of a giant impact and so the simplest explanation for the small satellites is that they accreted from debris of that collision. The Pluto-Charon binary has evolved outward since its formation due to tidal forces...

  6. Blossom Point Satellite Tracking and Command Station

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: The Blossom Point Satellite Command and Tracking Facility (BP) provides engineering and operational support to several complex space systems for the Navy...

  7. Commissioning of the Tevatron Satellite Refrigeration system

    International Nuclear Information System (INIS)

    This chapter describes the cooling of the new Fermilab 6 km circumference superconducting proton accelerator by a 5000 L/h central helium liquefier (CHL) coupled with 24 satellite refrigerators (966W each). The Tevatron Satellite Refrigeration system includes a liquid helium/liquid nitrogen transfer line made up of twenty six-250 m long sections. Topics considered include transfer line operation, compressor system operation, satellite refrigeration operational experience, contamination, expansion engine efficiency, control loop stability, pressure drop, the magnet system operational experience, magnet cooldown, vacuum deficiencies, and magnet excitation. It is concluded that the satellite refrigerator concept has proven to be a reliable design for the Tevatron

  8. TUBSAT-1, satellite technology for educational purposes

    Science.gov (United States)

    Ginati, A.

    1988-01-01

    TUBSAT-1 (Technical University of Berlin Satellite) is an experimental low-cost satellite within the NASA Get Away Special (GAS) program. This project is being financed by the German BMFT (Federal Ministry for Research and Technology), mainly for student education. The dimensions and weight are determined by GAS requirements and the satellite will be ejected from the space shuttle into an approximately 300-km circular orbit. It is a sun/star oriented satellite with an additional spin stabilization mode. The first planned payload is to be used for observing flight paths of migratory birds from northern Europe to southern Africa and back.

  9. International Satellite Cloud Climatology Project (ISCCP)

    Data.gov (United States)

    National Aeronautics and Space Administration — International Satellite Cloud Climatology Project (ISCCP) focuses on the distribution and variation of cloud radiative properties to improve the understanding of...

  10. Ravens satellite mission concept study

    CERN Document Server

    Donovan, Eric F

    2011-01-01

    The concept for Ravens satellite mission was proposed in response to a CSA AO for potential Canadian mission contributions to the International Living With a Star (ILWS) program. Ravens was conceived of to fill an important gap in the ILWS program: global imaging. Ravens will build on the heritage of world-class global imaging carried out in Canada. It would do much more than provide global observations to complete the system level capabilities of ILWS. Ravens would be comprised of two satellites on elliptical polar orbits, relatively phased on those orbits to provide the first-ever continuous (ie., 24 hours per day 7 days per week) global imaging of the northern hemisphere auroral and polar cap regions. This would provide the first-ever unbroken sequences of global images of the auroral response during long duration geomagnetic processes like storms and steady magnetospheric convection events. Ravens could track the spatio-temporal evolution of the global electron and proton auroral distribution, and would o...

  11. Automated satellite telemetry processing system

    Science.gov (United States)

    Parunakian, David; Kalegaev, Vladimir; Barinova, Vera

    In this paper we describe the design and important implementation details of the new automated system for processing satellite telemetry developedat Skobeltsyn Institute of Nuclear Physics of Moscow State University (SINP MSU) . We discuss the most common tasks and pitfall for such systems built around data stream from a single spacecraft or a single instrument, and suggest a solution that allows to quickly develop telemetry processing modules and to integrate them with an existing polling mechanism, support infrastructure and data storage in Oracle or MySQL database systems. We also demonstrate the benefits of this approach using modules for processing three different spacecraft data streams: Coronas-Photon (2009-003A), Tatiana-2 (2009-049D) and Meteor-M no.1 (2009-049A). The data format and protocols used by each of these spacecraft have distinct peculiarities, which nevertheless did not pose a problem for integrating their modules into the main system. Remote access via web interface to Oracle databases and sophisticated visualization tools create a possibility of efficient scientific exploitation of satellite data. Such a system is already deployed at the web portal of the Space Monitoring Data Center (SMDC) of SINP MSU (http://smdc.sinp.msu.ru).

  12. The Canadian mobile satellite program

    Science.gov (United States)

    Boudreau, P. M.; Breithaupt, R. W.; McNally, J. L.

    The progressions and selection of design features for the Canadian segment of a mobile satellite (MSAT) communications system are traced. The feasibility study for a satellite-based public and government mobile communications service to underserved areas was carried out between 1980-82. The results covered the market demand, commercial viability, user cost-benefit, and spacecraft concepts. A subsequent 2 yr study was initiated to proceed with project definition. A market of 1.1 million users was identified in all of Canada, with MSAT replacing other systems for 50 percent of the market. Operations would be in the 806-890 MHz range. Traffic will be routed through gateway links functioning in the 8/7 GHz SHF band while the mobile units will be connected through an 821-825 MHz up link and an 866-870 MH downlink. New technologies will be needed for a central control station, the gateway stations, and the base stations for the mobile radio service, the mobile user terminals, and data collection platforms.

  13. Interim Service ISDN Satellite (ISIS) simulator development for advanced satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The simulation development associated with the network models of both the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures is documented. The ISIS Network Model design represents satellite systems like the Advanced Communications Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) Program, moves all control and switching functions on-board the next generation ISDN communications satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete event simulation experiments will be performed with these models using various traffic scenarios, design parameters, and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

  14. Doppler factors in satellite-to-satellite tracking. [with relativistic effects

    Science.gov (United States)

    Marini, J. W.

    1974-01-01

    The Doppler factors occurring in range rate satellite-to-satellite tracking measurements are derived with special relativistic effects included. The error resulting from the use of simplified expressions for these factors is discussed.

  15. Economics of satellite communications systems

    Science.gov (United States)

    Pritchard, Wilbur L.

    This paper is partly a tutorial, telling systematically how one goes about calculating the total annual costs of a satellite communications system, and partly the expression of some original ideas on the choice of parameters so as to minimize these costs. The calculation of costs can be divided into two broad categories. The first is technical and is concerned with estimating what particular equipment will cost and what will be the annual expense to maintain and operate it. One starts in the estimation of any new system by listing the principal items of equipment, such as satellites, earth stations of various sizes and functions, telemetry and tracking equipment and terrestrial interfaces, and then estimating how much each item will cost. Methods are presented for generating such estimates, based on a knowledge of the gross parameters, such as antenna size, coverage area, transmitter power and information rate. These parameters determine the system performance and it is usually possible, knowing them, to estimate the costs of the equipment rather well. Some formulae based on regression analyses are presented. Methods are then given for estimating closely related expenses, such as maintenance and operation, and then an approximate method is developed for estimating terrestrial interconnection costs. It is pointed out that in specific cases when tariff and geographical information are available, it is usually better to work with specific data, but nonetheless it is often desirable, especially in global system estimating, to approximate these interconnect costs without recourse to individual tariffs. The procedure results in a set of costs for the purchase of equipment and its maintenance, and a schedule of payments. Some payments will be incurred during the manufacture of the satellite and before any systems operation, but many will not be incurred until the system is no longer in use, e.g. incentives. In any case, with the methods presented in the first section, one

  16. Satellite orbit determination using satellite gravity gradiometry observations in GOCE mission perspective

    OpenAIRE

    Bobojć, A.; Drożyner, A.

    2003-01-01

    Between the years 2004 and 2005 the launch of the first gradiometric satellite is planned. This satellite will be an important element of the Gravity Field and Steady ? State Ocean Circulation Explorer Mission (GOCE). This mission is one of the reasons for performing the simulation research of the Satellite Gravity Gradiometry. Our work contains the theory description and simulation results of the satellite orbit determination using the gravity tensor observations. In the process of the satel...

  17. Satellite orbit determination using satellite gravity gradiometry observations in GOCE mission perspective

    OpenAIRE

    Bobojć, A.; Drożyner, A.

    2003-01-01

    Between the years 2004 and 2005 the launch of the first gradiometric satellite is planned. This satellite will be an important element of the Gravity Field and Steady – State Ocean Circulation Explorer Mission (GOCE). This mission is one of the reasons for performing the simulation research of the Satellite Gravity Gradiometry. Our work contains the theory description and simulation results of the satellite orbit determination using the gravity tensor observations. In ...

  18. China Land Observation Satellite Third User Conference Promotes The Applications Of Domestic Satellite Data

    Institute of Scientific and Technical Information of China (English)

    Zong He

    2009-01-01

    @@ China Land Observation Satellite Third User Conference with the theme of "Strengthening cooperation,enlarging sharing and promoting the application of domestic satellite data" was held on July 16,2009 in Beijing. The conference was hosted by China Centre for Resources Satellite Data and Applications(CRESDA),a subsidiary of China Aerospace Science and Technology Corporation (CASC).

  19. Determination of the number of navigation satellites within satellite acquisition range

    International Nuclear Information System (INIS)

    The problem of determination of the number of navigation satellites within acquisition range with regard to antenna systems configuration and stochastic land remote sensing satellite maneuvers is the subject considered in the paper. Distribution function and density function of the number of navigation satellites within acquisition range are obtained

  20. History of Satellite TV Broadcasting and Satellite Broadcasting Market in Turkey

    OpenAIRE

    Mihalis KUYUCU

    2015-01-01

    The present study analyses the satellite broadcasting that is the first important development that emerged as a result of digitalization in communication technologies and its reflections in Turkey. As the first milestone in the globalization of television broadcasting, satellite broadcasting provided substantial contribution towards the development of the media. Satellite bro adcasting both increased the broadcasting qualit...

  1. Synchronized Position Hold, Engage, Reorient, Experimental Satellites

    Science.gov (United States)

    Miller, David W.; Wilson, Edward; How, Jonathan; Sanenz-Otero, Alvar; Chamitoff, Gregory

    2009-01-01

    Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) are bowling-ball sized spherical satellites. They will be used inside the space station to test a set of well-defined instructions for spacecraft performing autonomous rendezvous and docking maneuvers. Three free-flying spheres will fly within the cabin of the station, performing flight formations. Each satellite is self-contained with power, propulsion, computers and navigation equipment. The results are important for satellite servicing, vehicle assembly and formation flying spacecraft configurations. SPHERES is a testbed for formation flying by satellites, the theories and calculations that coordinate the motion of multiple bodies maneuvering in microgravity. To achieve this inside the ISS cabin, bowling-ball-sized spheres perform various maneuvers (or protocols), with one to three spheres operating simultaneously . The Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) experiment will test relative attitude control and station-keeping between satellites, re-targeting and image plane filling maneuvers, collision avoidance and fuel balancing algorithms, and an array of geometry estimators used in various missions. SPHERES consists of three self-contained satellites, which are 18 sided polyhedrons that are 0.2 meter in diameter and weigh 3.5 kilograms. Each satellite contains an internal propulsion system, power, avionics, software, communications, and metrology subsystems. The propulsion system uses CO2, which is expelled through the thrusters. SPHERES satellites are powered by AA batteries. The metrology subsystem provides real-time position and attitude information. To simulate ground station-keeping, a laptop will be used to transmit navigational data and formation flying algorithms. Once these data are uploaded, the satellites will perform autonomously and hold the formation until a new command is given.

  2. HISTORICAL RESTORSPECTIVE OF COMUNICATION SATELLITES

    Directory of Open Access Journals (Sweden)

    Francisco Sacristán Romero

    2006-04-01

    Full Text Available SUMMARY This article comprises of an investigation that approaches a so complex subject and in process as the trajectory, from its birth like project, of the Spanish satellite of communications HISPASAT. HISPASAT supposes to enter in the more fascinating world of the technologies out poste with the risk of believing have approval part of the possibilities that it offers, when in fact not we have begun the study of a plan in transition. The investigators that come behind us will extend and enrich the information on the great legacy which, from already, are leaving net Spanish technical and human resources. HISPASAT offers the possibility that the languages and the cultures of our country transfer the international borders and they enter in corners of Europe, America and Africa where it had a superficial knowledge of our customs, wealthy and stronger traditions.

  3. Satellite-Derived Management Zones

    Science.gov (United States)

    Lepoutre, Damien; Layrol, Laurent

    2005-01-01

    The term "satellite-derived management zones" (SAMZ) denotes agricultural management zones that are subdivisions of large fields and that are derived from images of the fields acquired by instruments aboard Earth-orbiting satellites during approximately the past 15 years. "SAMZ" also denotes the methodology and the software that implements the methodology for creating such zones. The SAMZ approach is one of several products of continuing efforts to realize a concept of precision agriculture, which involves optimal variations in seeding, in application of chemicals, and in irrigation, plus decisions to farm or not to farm certain portions of fields, all in an effort to maximize profitability in view of spatial and temporal variations in the growth and health of crops, and in the chemical and physical conditions of soils. As used here, "management zone" signifies, more precisely, a subdivision of a field within which the crop-production behavior is regarded as homogeneous. From the perspective of precision agriculture, management zones are the smallest subdivisions between which the seeding, application of chemicals, and other management parameters are to be varied. In the SAMZ approach, the main sources of data are the archives of satellite imagery that have been collected over the years for diverse purposes. One of the main advantages afforded by the SAMZ approach is that the data in these archives can be reused for purposes of precision agriculture at low cost. De facto, these archives contain information on all sources of variability within a field, including weather, crop types, crop management, soil types, and water drainage patterns. The SAMZ methodology involves the establishment of a Web-based interface based on an algorithm that generates management zones automatically and quickly from archival satellite image data in response to requests from farmers. A farmer can make a request by either uploading data describing a field boundary to the Web site or else

  4. Astrophysics with small satellites in Scandinavia

    DEFF Research Database (Denmark)

    Lund, Niels

    2003-01-01

    The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.......The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved....

  5. Satellite Remote Sensing in Offshore Wind Energy

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Astrup, Poul;

    2013-01-01

    Satellite remote sensing of ocean surface winds are presented with focus on wind energy applications. The history on operational and research-based satellite ocean wind mapping is briefly described for passive microwave, scatterometer and synthetic aperture radar (SAR). Currently 6 GW installed...

  6. IMPLEMENTATION OF AERONAUTICAL LOCAL SATELLITE AUGMENTATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Stojce Ilcev

    2011-03-01

    Full Text Available Abstract. This paper introduces development and implementation of new Local Satellite AugmentationSystem as an integration component of the Regional Satellite Augmentation System (RSAS employingcurrent and new Satellite Communications, Navigation and Surveillance (CNS for improvement of the AirTraffic Control (ATC and Air Traffic Management (ATM and for enhancement safety systems includingtransport security and control of flights in all stages, airport approaching, landing, departures and allmovements over airport surface areas. The current first generation of the Global Navigation Satellite SystemGNSS-1 applications are represented by fundamental military solutions for Position, Velocity and Time ofthe satellite navigation and determination systems such as the US GPS and Russian GLONASS (Former-USSR requirements, respectively. The establishment of Aeronautical CNS is also discussed as a part ofGlobal Satellite Augmentation Systems of GPS and GLONASS systems integrated with existing and futureRSAS and LSAS in airports areas. Specific influence and factors related to the Comparison of the Currentand New Aeronautical CNS System including the Integration of RSAS and GNSS solutions are discussedand packet of facts is determined to maximize the new satellite Automatic Dependent Surveillance System(ADSS and Special Effects of the RSAS Networks. The possible future integration of RSAS and GNSS andthe common proposal of the satellite Surface Movement Guidance and Control are presented in thechangeless ways as of importance for future enfacements of ATC and ATM for any hypothetical airportinfrastructure.Keywords: ADSS, ATC, ATM, CNS, GSAS, LRAS, RSAS, SMGC, Special Effects of RSAS.

  7. Astrophysics with small satellites in Scandinavia

    DEFF Research Database (Denmark)

    Lund, Niels

    The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.......The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved....

  8. RFP for CNES micro satellite program

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Jørgensen, Finn E; Betto, Maurizio;

    1999-01-01

    This document descibes the ASC STAR TRACKER (performance, functionality, requirements etc.) to the Centre National d'Etudes Spatiales (CNES) for their micro Satellites.......This document descibes the ASC STAR TRACKER (performance, functionality, requirements etc.) to the Centre National d'Etudes Spatiales (CNES) for their micro Satellites....

  9. Interim Service ISDN Satellite (ISIS) hardware experiment design for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Design for Advanced Satellite Designs describes the design of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into time division multiple access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the V.35 interface for satellite uplink. The same ISTA converts in the opposite direction the V.35 to U-interface data with a simple switch setting.

  10. Future Satellite Gravimetry and Earth Dynamics

    CERN Document Server

    Flury, Jakob

    2005-01-01

    Currently, a first generation of dedicated satellite missions for the precise mapping of the Earth’s gravity field is in orbit (CHAMP, GRACE, and soon GOCE). The gravity data from these satellite missions provide us with very new information on the dynamics of planet Earth. In particular, on the mass distribution in the Earth’s interior, the entire water cycle (ocean circulation, ice mass balance, continental water masses, and atmosphere), and on changes in the mass distribution. The results are fascinating, but still rough with respect to spatial and temporal resolution. Technical progress in satellite-to-satellite tracking and in gravity gradiometry will allow more detailed results in the future. In this special issue, Earth scientists develop visions of future applications based on follow-on high-precision satellite gravimetry missions.

  11. Capture of Irregular Satellites at Jupiter

    CERN Document Server

    Nesvorny, D; Deienno, R

    2014-01-01

    The irregular satellites of outer planets are thought to have been captured from heliocentric orbits. The exact nature of the capture process, however, remains uncertain. We examine the possibility that irregular satellites were captured from the planetesimal disk during the early Solar System instability when encounters between the outer planets occurred (Nesvorny, Vokrouhlicky & Morbidelli 2007, AJ 133; hereafter NVM07). NVM07 already showed that the irregular satellites of Saturn, Uranus and Neptune were plausibly captured during planetary encounters. Here we find that the current instability models present favorable conditions for capture of irregular satellites at Jupiter as well, mainly because Jupiter undergoes a phase of close encounters with an ice giant. We show that the orbital distribution of bodies captured during planetary encounters provides a good match to the observed distribution of irregular satellites at Jupiter. The capture efficiency for each particle in the original transplanetary d...

  12. Air and sea rescue via satellite systems

    Science.gov (United States)

    Scales, W. C.; Swanson, R.

    1984-03-01

    Two approaches to a satellite system for air and sea rescue to be put into use by the 1990s, one employing polar-orbiting satellites and the other using fixed geosynchronous satellites over the equator, are discussed. A battery-powered transmitter on a ship or aircraft would be activated in an accident to emit a low-power omnidirectional signal that would be relayed by a satellite to an earth station. The polar-orbiting approach, now being evaluated on a small-scale with the Cospas-Sarsat system, allows complete coverage of the earth, including the poles, and provides a fix on the origin of the distress signals by means of the Doppler shift. A parallel effort for the testing of geostationary satellites to measure system sensitivity to various interference sources, to optimize design, and to measure land and sea performance is reviewed.

  13. High power communication satellites power systems study

    International Nuclear Information System (INIS)

    This paper discusses a DOE-funded study to evaluate the commercial attractiveness of high power communication satellites and assesses the attributes of both conventional photovoltaic and reactor power systems. This study brings together a preeminent US Industry/Russian team to cooperate on the role of high power communication satellites in the rapidly expanding communications revolution. These high power satellites play a vital role in assuring availability of universally accessible, wide bandwidth communications, for high definition TV, super computer networks and other services. Satellites are ideally suited to provide the wide bandwidths and data rates required and are unique in the ability to provide services directly to the users. As new or relocated markets arise, satellites offer a flexibility that conventional distribution services cannot match, and it is no longer necessary to be near population centers to take advantage of the telecommunication revolution. The geopolitical implications of these substantially enhanced communications capabilities will be significant

  14. Temperature diagnostics using lithium-like satellites

    International Nuclear Information System (INIS)

    A 60-kJ theta-pinch was operated at a filling pressure of 16 mtorr using a gas mixture of 2% neon and 98% helium. The resonance and intercombination lines from Ne IX and the Li-like satellites were observed with a Bragg crystal monochromator. The electron temperature of the plasma was deduced from the intensity ratios of the Ne IX resonance line and the dielectronic satellites using recent theoretical calculations. The temperature values ranged from 210 eV to 340 eV during the time of occurrence of these satellites. The temperature measured at 1.0 μs by laser scattering for a similar plasma condition was in close agreement with that obtained by the resonance line/satellite ratio. This lends confidence to use of the satellite technique for temperature measurements in other plasmas

  15. Regulation of satellite cell function in sarcopenia

    Directory of Open Access Journals (Sweden)

    Stephen E Alway

    2014-09-01

    Full Text Available The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell function that is impacted by the environment (niche of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse or rehabilitation in sarcopenic muscles. Nutritional intervention provides one therapeutic strategy to improve the satellite cell niche and systemic factors, with the goal of improving satellite cell function in aging muscles. Although many elderly persons consume various nutraceuticals with the hope of improving health, most of these compounds have not been thoroughly tested, and the impacts that they might have on sarcopenia, and satellite cell function are not clear. This review discusses data pertaining to the satellite cell responses and function in aging skeletal muscle, and the impact that three compounds: resveratrol, green tea catechins and β-Hydroxy-β-methylbutyrate have on regulating satellite cell function and therefore contributing to reducing sarcopenia or improving muscle mass after disuse in aging. The data suggest that these nutraceutical compounds improve satellite cell function during rehabilitative loading in animal models of aging after disuse (i.e., muscle regeneration. While these compounds have not been rigorously tested in humans, the data from animal models of aging provide a strong basis for conducting additional focused work to determine if these or other nutraceuticals can offset the muscle losses, or improve regeneration in sarcopenic muscles of older humans via improving satellite cell function.

  16. Regulation of satellite cell function in sarcopenia.

    Science.gov (United States)

    Alway, Stephen E; Myers, Matthew J; Mohamed, Junaith S

    2014-01-01

    The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell) function that is impacted by the environment (niche) of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse, or rehabilitation in sarcopenic muscles. Nutritional intervention provides one therapeutic strategy to improve the satellite cell niche and systemic factors, with the goal of improving satellite cell function in aging muscles. Although many elderly persons consume various nutraceuticals with the hope of improving health, most of these compounds have not been thoroughly tested, and the impacts that they might have on sarcopenia and satellite cell function are not clear. This review discusses data pertaining to the satellite cell responses and function in aging skeletal muscle, and the impact that three compounds: resveratrol, green tea catechins, and β-Hydroxy-β-methylbutyrate have on regulating satellite cell function and therefore contributing to reducing sarcopenia or improving muscle mass after disuse in aging. The data suggest that these nutraceutical compounds improve satellite cell function during rehabilitative loading in animal models of aging after disuse (i.e., muscle regeneration). While these compounds have not been rigorously tested in humans, the data from animal models of aging provide a strong basis for conducting additional focused work to determine if these or other nutraceuticals can offset the muscle losses, or improve regeneration in sarcopenic muscles of older humans via improving satellite cell function. PMID:25295003

  17. Evaluation of Cardiovascular Risk Scores Applied to NASA's Astronant Corps

    Science.gov (United States)

    Jain, I.; Charvat, J. M.; VanBaalen, M.; Lee, L.; Wear, M. L.

    2014-01-01

    In an effort to improve cardiovascular disease (CVD) risk prediction, this analysis evaluates and compares the applicability of multiple CVD risk scores to the NASA Astronaut Corps which is extremely healthy at selection.

  18. Design of the ISAT-1 Satellite Thermal Control System

    OpenAIRE

    Clay, Joseph

    1994-01-01

    Satellite technology improves the daily lives of almost all human beings. Satellites aid in communication, weather prediction, and global positioning. Other uses for satellites include conducting scientific experiments in micro gravity and space exploration missions. A major constraint placed on all satellites is the cost of launch. With a larger or heavier satellite, a larger more powerful launch vehicle is need. This larger launch vehicle increases the overall satellite cost. The developmen...

  19. Myostatin negatively regulates satellite cell activation and self-renewal

    OpenAIRE

    McCroskery, Seumas; Thomas, Mark; Maxwell, Linda; Sharma, Mridula; Kambadur, Ravi

    2003-01-01

    Satellite cells are quiescent muscle stem cells that promote postnatal muscle growth and repair. Here we show that myostatin, a TGF-β member, signals satellite cell quiescence and also negatively regulates satellite cell self-renewal. BrdU labeling in vivo revealed that, among the Myostatin-deficient satellite cells, higher numbers of satellite cells are activated as compared with wild type. In contrast, addition of Myostatin to myofiber explant cultures inhibits satellite cell activation. Ce...

  20. Satellite Meteorology Education & Training Resources from COMET

    Science.gov (United States)

    Abshire, W. E.; Dills, P. N.; Weingroff, M.; Lee, T. F.

    2012-12-01

    The COMET® Program (www.comet.ucar.edu) receives funding from NOAA NESDIS as well as EUMETSAT and the Meteorological Service of Canada to support education and training in satellite meteorology. These partnerships enable COMET to create educational materials of global interest on geostationary and polar-orbiting remote sensing platforms. These materials focus on the capabilities and applications of current and next-generation satellites and their relevance to operational forecasters and other user communities. By partnering with experts from the Naval Research Laboratory, NOAA-NESDIS and its Cooperative Institutes, Meteorological Service of Canada, EUMETSAT, and other user communities, COMET stimulates greater use of satellite data observations and products. This presentation provides an overview of COMET's recent satellite education efforts in the area of polar orbiting satellites. COMET has a new module on Suomi NPP, which describes the satellite system and discusses the improvements that it is bringing to forecasting, numerical weather prediction, and environmental monitoring. COMET has also published an updated version of its module on the VIIRS instrument. "Imaging with VIIRS: A Convergence of Technologies and Experience, 2nd Edition" covers the instrument's enhanced capabilities by examining the systems that contributed to its development. Special attention is paid to the Day/Night Visible channel as VIIRS is the first instrument on a civilian satellite to image atmospheric and terrestrial features with and without moonlight. An upcoming module will exclusively focus on nighttime imaging with the VIIRS Day/Night Band (DNB). "Applications of the VIIRS Day-Night Band" will introduce the capabilities of DNB imagery to a wide audience ranging from forecasters and emergency managers to wildfire fighters and oceanographers. DNB products will be compared to traditional satellite products made from infrared data, including the "fog" product. Users will learn how DNB

  1. Satellite antenna management system and method

    Science.gov (United States)

    Leath, Timothy T (Inventor); Azzolini, John D (Inventor)

    1999-01-01

    The antenna management system and method allow a satellite to communicate with a ground station either directly or by an intermediary of a second satellite, thus permitting communication even when the satellite is not within range of the ground station. The system and method employ five major software components, which are the control and initialization module, the command and telemetry handler module, the contact schedule processor module, the contact state machining module, and the telemetry state machine module. The control and initialization module initializes the system and operates the main control cycle, in which the other modules are called. The command and telemetry handler module handles communication to and from the ground station. The contact scheduler processor module handles the contact entry schedules to allow scheduling of contacts with the second satellite. The contact and telemetry state machine modules handle the various states of the satellite in beginning, maintaining and ending contact with the second satellite and in beginning, maintaining and ending communication with the satellite.

  2. Alignments between galaxies, satellite systems and haloes

    CERN Document Server

    Shao, Shi; Frenk, Carlos S; Gao, Liang; Crain, Robert A; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-01-01

    The spatial distribution of the satellite populations of the Milky Way and Andromeda are puzzling in that they are nearly perpendicular to the disks of their central galaxies. To understand the origin of such configurations we study the alignment of the central galaxy, satellite system and dark matter halo in the largest of the "Evolution and Assembly of GaLaxies and their Environments" (EAGLE) simulation. We find that centrals and their satellite systems tend to be well aligned with their haloes, with a median misalignment angle of $33^{\\circ}$ in both cases. While the centrals are better aligned with the inner $10$ kpc halo, the satellite systems are better aligned with the entire halo indicating that satellites preferentially trace the outer halo. The central - satellite alignment is weak (median misalignment angle of $52^{\\circ}$) and we find that around $20\\%$ of systems have a misalignment angle larger than $78^{\\circ}$, which is the value for the Milky Way. The central - satellite alignment is a conseq...

  3. Satellite power system salvage and disposal alternatives

    Science.gov (United States)

    1980-11-01

    A wide range of salvage options for the SPS satellite, ranging from use in and beyond geosynchronous orbit to use in low Earth orbit in return and use on Earth are presented. The satellite can be used intact to provide power for various purposes, it can be cannibalized or it can be melted down to supply materials for space or ground based products. The use of SPS beyond its nominal lifetime provides value that can be deducted from the SPS capital investment cost. The present value of the salvage value of the SPS satellites, referenced to the system initial operation data, is on the order of five to ten percent of its on-orbit capital cost. (Given a 30 year satellite lifetime and a four percent discount rate, the theoretical maximum salvage value is 30.8 percent of the capital cost.) The SPS demonstration satellite is available some 30 years earlier than the first full scale SPS satellite and has a salvage value on the order of 80 percent of its on-orbit capital cost. In the event that it becomes desirable to dispose of either the demonstration of full scale SPS satellite, a number of disposal options is presented for which intact disposal costs are less than one percent of capital costs.

  4. PRMT7 Preserves Satellite Cell Regenerative Capacity

    Directory of Open Access Journals (Sweden)

    Roméo Sébastien Blanc

    2016-02-01

    Full Text Available Regeneration of skeletal muscle requires the continued presence of quiescent muscle stem cells (satellite cells, which become activated in response to injury. Here, we report that whole-body protein arginine methyltransferase PRMT7−/− adult mice and mice conditionally lacking PRMT7 in satellite cells using Pax7-CreERT2 both display a significant reduction in satellite cell function, leading to defects in regenerative capacity upon muscle injury. We show that PRMT7 is preferentially expressed in activated satellite cells and, interestingly, PRMT7-deficient satellite cells undergo cell-cycle arrest and premature cellular senescence. These defects underlie poor satellite cell stem cell capacity to regenerate muscle and self-renew after injury. PRMT7-deficient satellite cells express elevated levels of the CDK inhibitor p21CIP1 and low levels of its repressor, DNMT3b. Restoration of DNMT3b in PRMT7-deficient cells rescues PRMT7-mediated senescence. Our findings define PRMT7 as a regulator of the DNMT3b/p21 axis required to maintain muscle stem cell regenerative capacity.

  5. Optimization of satellite constellation reconfiguration maneuvers

    Science.gov (United States)

    Appel, Leonid; Guelman, Moshe; Mishne, David

    2014-06-01

    Constellation satellites are required to perform orbital transfer maneuvers. Orbital transfer maneuvers, as opposed to orbital correction maneuvers, are seldom performed but require a substantial amount of propellant for each maneuver. The maneuvers are performed in order to obtain the desired constellation configuration that satisfies the coverage requirements. In most cases, the single-satellite position is immaterial; rather the relative position between constellation multiple-satellites is to be controlled. This work deals with the solution to the coupled optimization problem of multiple-satellite orbital transfer. The studied problem involves a coupled formulation of the terminal conditions of the satellites. The solution was achieved using functional optimization techniques by a combined algorithm. The combined algorithm is based on the First Order Gradient and Neighboring-Extremals Algorithms. An orbital transfer optimization tool was developed. This software has the ability to consider multiple satellites with coupled terminal conditions. A solution to the multiple-satellite orbital transfer optimization problem is presented. A comparison of this solution to the uncoupled case is presented in order to review the benefits of using this approach. It is concluded that the coupled transfer maneuver solution approach is more computationally efficient and more accurate. Numerical solutions for a number of representative cases are presented.

  6. Satellite Application for Disaster Management Information Systems

    Science.gov (United States)

    Okpanachi, George

    Abstract Satellites are becoming increasingly vital to modern day disaster management activities. Earth observation (EO) satellites provide images at various wavelengths that assist rapid-mapping in all phases of the disaster management cycle: mitigation of potential risks in a given area, preparedness for eventual disasters, immediate response to a disaster event, and the recovery/reconstruction efforts follo wing it. Global navigation satellite systems (GNSS) such as the Global Positioning System (GPS) assist all the phases by providing precise location and navigation data, helping manage land and infrastructures, and aiding rescue crews coordinate their search efforts. Effective disaster management is a complex problem, because it involves many parameters, which are usually not easy to measure and even identify: Analysis of current situation, planning, optimum resource management, coordination, controlling and monitoring current activities and making quick and correct decisions are only some of these parameters, whose complete list is very long. Disaster management information systems (DMIS) assist disaster management to analyse the situation better, make decisions and suggest further actions following the emergency plans. This requires not only fast and thorough processing and optimization abilities, but also real-time data provided to the DMIS. The need of DMIS for disaster’s real-time data can be satisfied by small satellites data utilization. Small satellites can provide up-to-data, plus a better media to transfer data. This paper suggests a rationale and a framework for utilization of small Satellite data by DMIS. DMIS should be used ‘’before’’, ‘’during’’ and ‘’after’’ the disasters. Data provided by the Small Satellites are almost crucial in any period of the disasters, because early warning can save lives, and satellite data may help to identify disasters before they occur. The paper also presents’ ‘when’’,

  7. Protected transitional solution to transformational satellite communications

    Science.gov (United States)

    Brand, Jerry C.

    2005-06-01

    As the Warfighter progresses into the next generation battlefield, transformational communications become evident as an enabling technology. Satellite communications become even more vital as the battles range over greater non-contiguous spaces. While current satellite communications provide suitable beyond line-of-sight communications and the Transformational Communications Architecture (TCA) sets the stage for sound information exchange, a realizable transition must occur to ensure successful succession to this higher level. This paper addresses the need for a planned escalation to the next generation satellite communications architecture and offers near-term alternatives. Commercial satellite systems continue to enable the Warfighter to reach back to needed information resources, providing a large majority of available bandwidth. Four areas of concentration for transition include encrypted Telemetry, Tracking and Control (or Command) (TT&C), encrypted and covered data, satellite attack detection and protection, and operational mobility. Solution methodologies include directly embedding COMSEC devices in the satellites and terminals, and supplementing existing terminals with suitable equipment and software. Future satellites planned for near-term launches can be adapted to include commercial grade and higher-level secure equipment. Alternately, the expected use of programmable modems (Software Defined Radios (SDR)) enables incorporation of powerful cipher methods approaching military standards as well as waveforms suitable for on-the-move operation. Minimal equipment and software additions on the satellites can provide reasonable attack detection and protection methods in concert with the planned satellite usage. Network management suite modifications enable cohesive incorporation of these protection schemes. Such transitional ideas offer a smooth and planned transition as the TCA takes life.

  8. Saturn's F ring and shepherd satellites a natural outcome of satellite system formation

    Science.gov (United States)

    Hyodo, Ryuki; Ohtsuki, Keiji

    2015-09-01

    Saturn's F ring is a narrow ring of icy particles, located 3,400 km beyond the outer edge of the main ring system. Enigmatically, the F ring is accompanied on either side by two small satellites, Prometheus and Pandora, which are called shepherd satellites. The inner regular satellites of giant planets are thought to form by the accretion of particles from an ancient massive ring and subsequent outward migration. However, the origin of a system consisting of a narrow ring and shepherd satellites remains poorly understood. Here we present N-body numerical simulations to show that a collision of two of the small satellites that are thought to accumulate near the main ring's outer edge can produce a system similar to the F ring and its shepherd satellites. We find that if the two rubble-pile satellites have denser cores, such an impact results in only partial disruption of the satellites and the formation of a narrow ring of particles between two remnant satellites. Our simulations suggest that the seemingly unusual F ring system is a natural outcome at the final stage of the formation process of the ring-satellite system of giant planets.

  9. Solar array experiments on the Sphinx satellite

    Science.gov (United States)

    Stevens, N. J.

    1973-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations; the edge illuminated-multijunction cells, the Teflon encased cells and the violet cells.

  10. Egypt satellite images for land surface characterization

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay

    Satellite images provide information on the land surface properties. From optical remote sensing images in the blue, green, red and near-infrared part of the electromagnetic spectrum it is possible to identify a large number of surface features. The report briefly describes different satellite...... images used for mapping the vegetation cover types and other land cover types in Egypt. The mapping ranges from 1 km resolution to 30 m resolution. The aim is to provide satellite image mapping with land surface characteristics relevant for roughness mapping....

  11. New Satellite Services for the Next Millennium

    Science.gov (United States)

    Wakeling, J.

    There are many new satellite communication systems that are either on the verge of commercial service or in the advanced planning and design stages for launch in the next millennium. Many will address what are considered to be new markets for satellites, using services and applications originally developed for terrestrial networks. Many of these services are network oriented and this will require a step change in the way that the satellite resource is managed if these systems are to succeed. This paper discusses these issues and offers some thoughts on what additional future services this change in approach may generate in the next millennium.

  12. KOMPSAT Satellite Launch and Deployment Operations

    Science.gov (United States)

    Baek, Myung-Jin; Chang, Young-Keun; Lee, Jin-Ho

    1999-12-01

    In this paper, KOMPSAT satellite launch and deployment operations are discussed. The U.S. Taurus launch vehicle delivers KOMPSAT satellite into the mission orbit directly. Launch and deployment operations is monitored and controlled by several international ground stations including Korean Ground Station (KGS). After separation from launch vehicle, KOMPSAT spacecraft deploys solar array by on-board autonomous stored commands without ground inter-vention and stabilizes the satellite such that solar arrays point to the sun. Autonomous ground communication is designed for KOMPSAT for the early orbit ground contact. KOMPSAT space-craft has capability of handing contingency situation by on-board fault management design to retry deployment sequence.

  13. Regional satellite systems: Are they "the solution?"

    Science.gov (United States)

    Ospina, Sylvia

    Regional satellite systems are in operation in Europe and the Arab League countries. Several others are under consideration for developing countries in Africa, Asia and South America. Studies have concluded that technically, the regional satellite systems are feasible. However, their viability depends on more than the succesful launch of a satellite. This paper analyzes the existing systems, extrapolates a few "lessons" from their experience and examines how they may be applied to the proposed systems. It is suggested that future feasibility studies should give some attention to terrestrial concerns: the physical infrastructure as well as economic and legal issues which will affect any regional system's viability.

  14. Star Formation Histories of the Galactic Satellites

    CERN Document Server

    Gilmore, G; Valls-Gabaud, D; Gilmore, Gerard; Hernandez, Xavier; Valls-Gabaud, David

    1999-01-01

    Late accretion models for formation of the Galactic halo require that many Galactic satellite galaxies have been cannibalised into the halo field. Comparison of the metallicity and age distribution function of stars in the surviving satellites with the apparently exclusively old stars in the field halo can constrain the importance of any such process. We have developed a new objective technique to determine star formation histories in dSph galaxies. We apply this technique to the surviving Galactic satellites, deducing an approximately uniform distribution of ages for the constituents, quite unlike the halo field stars. Thus, late accretion did not play a substantial part in Galactic halo formation.

  15. Telemedicine using mobile satellite communication.

    Science.gov (United States)

    Murakami, H; Shimizu, K; Yamamoto, K; Mikami, T; Hoshimiya, N; Kondo, K

    1994-05-01

    With a view to providing paramedical care within moving vehicles, a telemedicine technique using mobile satellite communication was proposed. With this technique, the diagnosis from a specialist and the emergency care under his/her instructions would be available on the spot without unnecessary delay. The characteristic problems of this technique were identified as: channel capacity, size of the system, reliability of vital sign transmission, real-time operation and electromagnetic interference. Measures against these problems were devised, and their effectiveness was analyzed. A data format was designed and an experimental system was developed. The system can simultaneously transmit a color image, an audio signal, 3 channels ECG and blood pressures from a mobile station to a ground station. It can transmit an audio signal and error control signals from a ground station to a mobile station in a full duplex mode. Fundamental transmission characteristics were measured in a fixed station. Finally, experiments of medical data transmission were conducted with a navigating ship and an aircraft flying an international route. The measured threshold values of C/N(o) to guarantee satisfactory data reception were well below the lower boundary of C/N(o) of the communication link. Consequently, the feasibility of this technique was verified. PMID:8070809

  16. Evolutionary Pathways for Asteroid Satellites

    Science.gov (United States)

    Jacobson, Seth Andrew

    2015-08-01

    The YORP-induced rotational fission hypothesis is a proposed mechanism for the creation of small asteroid binaries, which make up approximately 1/6-th of the near-Earth asteroid and small Main Belt asteroid populations. The YORP effect is a radiative torque that rotationally accelerates asteroids on timescales of thousands to millions of years. As asteroids rotationally accelerate, centrifugal accelerations on material within the body can match gravitational accelerations holding that material in place. When this occurs, that material goes into orbit. Once in orbit that material coalesces into a companion that undergoes continued dynamical evolution.Observations with radar, photometric and direct imaging techniques reveal a diverse array of small asteroid satellites. These systems can be sorted into a number of morphologies according to size, multiplicity of members, dynamical orbit and spin states, and member shapes. For instance, singly synchronous binaries have short separation distances between the two members, rapidly rotating oblate primary members, and tidally locked prolate secondary members. Other confirmed binary morphologies include doubly synchronous, tight asynchronous and wide asynchronous binaries. Related to these binary morphologies are unbound paired asteroid systems and bi-lobate contact binaries.A critical test for the YORP-induced rotational fission hypothesis is whether the binary asteroids produced evolve to the observed binary and related systems. In this talk I will review how this evolution is believed to occur according to gravitational dynamics, mutual body tides and the binary YORP effect.

  17. The Transiting Exoplanet Survey Satellite

    CERN Document Server

    Ricker, George R; Vanderspek, Roland; Latham, David W; Bakos, Gaspar A; Bean, Jacob L; Berta-Thompson, Zachory K; Brown, Timothy M; Buchhave, Lars; Butler, Nathaniel R; Butler, R Paul; Chaplin, William J; Charbonneau, David; Christensen-Dalsgaard, Jorgen; Clampin, Mark; Deming, Drake; Doty, John; De Lee, Nathan; Dressing, Courtney; Dunham, E W; Endl, Michael; Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew J; Howard, Andrew W; Ida, Shigeru; Jenkins, Jon; Jernigan, Garrett; Johnson, John Asher; Kaltenegger, Lisa; Kawai, Nobuyuki; Kjeldsen, Hans; Laughlin, Gregory; Levine, Alan M; Lin, Douglas; Lissauer, Jack J; MacQueen, Phillip; Marcy, Geoffrey; McCullough, P R; Morton, Timothy D; Narita, Norio; Paegert, Martin; Palle, Enric; Pepe, Francesco; Pepper, Joshua; Quirrenbach, Andreas; Rinehart, S A; Sasselov, Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti, Alessandro; Stassun, Keivan G; Sullivan, Peter; Szentgyorgyi, Andrew; Torres, Guillermo; Udry, Stephane; Villasenor, Joel

    2014-01-01

    The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I<13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler missio...

  18. Cosmology with the Planck Satellite

    CERN Document Server

    CERN. Geneva

    2015-01-01

    Sketched out in 1992, selected by ESA in 1996, and launched in 2009, the Planck satellite was shut off in 2013, after a measuring mission that exceeded all expectations. The Planck collaboration delivered a first set of cosmological data and results in March 21st 2013, and the full set in February 2015. Part of the data delivery is a "definitive" map of the anisotropies of the Cosmic Microwave Background (CMB), its angular power spectrum together with their full statistical characterisation. The 2015 delivery also includes pioneering polarisation data. The temperature anisotropy map displays minuscule variations as a function of the observing direction, of rms ~100microK, of the fossil radiation around its mean temperature of 2.725K. Other maps reveal the CMB polarisation. The anisotropies are the imprint of the primordial fluctuations which initiated the growth of the large scale structures of the Universe, as transformed by their evolution, in particular during the first 370 000 years, as well as finer e...

  19. Hybrid Maritime Satellite Communication Antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst

    Hybrid antennas for a maritime satellite communication terminal with simultaneous operation at L- and Ka-band have been investigated. The frequency bands of interest are 1; 525:0 1; 660:5 MHz (RX+TX, RHCP), 19:7 20:2 (RX, LHCP) and 29:5 30:0 GHz (TX, RHCP), which are all part of the Inmarsat BGAN...... and Inmarsat GX services, respectively. The results of this study are three antenna concepts, which demonstrates high performance at both L- and Ka-band. A combined single/dual-reflector antenna is designed, which presents a favourable way of combining feed antennas for the diverse frequencies. This...... antenna enables the use of a conventional horn-fed dual-reflector for Ka-band, while a backfire helical antenna is used to form a single-reflector antenna at L-band. Simulations show excellent performance of the L-band backfire helical reflector antenna, due to the utilization of the entire antenna...

  20. RCA direct broadcast satellite configuration

    Science.gov (United States)

    Miller, R.; Buntschuh, R. F.

    System requirements and the spacecraft configuration for a DBS mission in 1986, contracted by RCA Americom, are presented. Performance features are to include a dc power of 315 W, a stationkeeping accuracy of up to 0.1 deg, a pointing accuracy of up to 0.05 deg, and continental U.S. coverage. Four on-orbit operating satellites are needed, each weighing at least 1100 kg, having antennas of about 3 m diam, six RF channels, and no eclipse operating requirements. Three-axis stabilization, a pivoted momentum wheel, hydrazine thrusters, a bipropellant liquid perigee stage, a solid apogee kick motor, Ni-Cd batteries, 230 W power amplifiers, and launch compatibility with the STS. The spacecraft length will be approximately 23 m with solar panels deployed. Feedhorns will be used on for transmissions and a switching network will be installed to optimize time zone coverage. Each spacecraft will generate over 1.38 kW of on-board RF power.

  1. Star Formation in Satellite Galaxies

    CERN Document Server

    Gutíerrez, C M; Funes, J G; Ribeiro, M B

    2006-01-01

    We present narrow-band observations of the H$\\alpha$ emission in a sample of 31 satellite orbiting isolated giant spiral galaxies. The sample studied spans the range $-19

  2. Femto-Satellite Sensor Node Demonstration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The key challenge for reducing a traditional satellite to such a small size is to remove the maximum possible functionality that is not critical for creating a...

  3. Satellite View of Alaska - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Satellite View of Alaska map layer is a 200-meter-resolution simulated-natural-color image of Alaska. Vegetation is generally green, with darker greens...

  4. Astrophysics: Rare data from a lost satellite

    Science.gov (United States)

    Blanton, Elizabeth

    2016-07-01

    The Hitomi astronomical satellite observed gas motions in the Perseus galaxy cluster shortly before losing contact with Earth. Its findings are invaluable to studies of cluster physics and cosmology. See Letter p.117

  5. A new digital land mobile satellite system

    Science.gov (United States)

    Schneider, Philip

    1990-01-01

    A description is given of the different digital services planned to be carried over existing and planned mobile satellite systems. These systems are then compared with analog services in terms of bandwidth and power efficiency. This comparison provides the rationale for the establishment of a digital land mobile satellite service (DLMSS) to use frequencies that are currently available but not yet assigned to a domestic mobile satellite system in the United States. The focus here is on the expected advantages of digital transmission techniques in accommodating additional mobile satellite systems in this portion of the spectrum, and how such techniques can fully satisfy voice, data and facsimile mobile communications requirements in a cost effective manner. A description is given of the system architecture of the DMLSS service proposed by the Geostar Messaging Corporation (GMC) and the market potential of DLMSS.

  6. Enabling Technology for Small Satellite Launch Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Access to space for Small Satellites is enabled by the use of excess launch capacity on existing launch vehicles. A range of sizes, form factors and masses need to...

  7. Enabling Technology for Small Satellite Launch Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Access to space for Small Satellites is enabled by the use of excess launch capacity on existing launch vehicles. A range of sizes, form factors and masses of small...

  8. Satellite View of Hawaii - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Satellite View of Hawaii map layer is a 200-meter-resolution simulated-natural-color image of Hawaii. Vegetation is generally green, with forests in darker...

  9. Megha-Tropiques satellite mission: sensors performances

    Science.gov (United States)

    Karouche, Nadia; Raju, Garuda

    2010-10-01

    MEGHA-TROPIQUES is an CNES-ISRO collaborative satellite mission designed to study processes related to large tropical convective systems and their life cycle, and to provide key elements related to atmospheric energy and water budget at various time and space scales. The satellite will perform high repetitive measurements using a low inclined (20°) orbit, and will carry 4 instruments : • MADRAS Instrument: A conical scanning microwave imager designed to estimate precipitations and clouds properties. • SAPHIR Instrument: A microwave sensor used to retrieve vertical humidity profiles. • SCARAB Instrument: An wide band optical radiometer used to retrieve Earth Radiation budget parameters. • GPS-ROS instrument: The sensor will provide temperature and humidity profiles of the Earth's atmosphere The MEGHA-TROPIQUES satellite is planned to be launched in 2011 by the Indian PSLV launcher. This paper presents the mission, the satellite definition and the measured performances of the sensors.

  10. Space industrialization - Education. [via communication satellites

    Science.gov (United States)

    Joels, K. M.

    1978-01-01

    The components of an educational system based on, and perhaps enhanced by, space industrialization communications technology are considered. Satellite technology has introduced a synoptic distribution system for various transmittable educational media. The cost of communications satellite distribution for educational programming has been high. It has, therefore, been proposed to utilize Space Shuttle related technology and Large Space Structures (LSS) to construct a system with a quantum advancement in communication capability and a quantum reduction in user cost. LSS for communications purposes have three basic advantages for both developed and emerging nations, including the ability to distribute signals over wide geographic areas, the reduced cost of satellite communications systems versus installation of land based systems, and the ability of a communication satellite system to create instant educational networks.

  11. Selected Geomagnetic Measurements From Several Satellites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — More than 17 million selected magnetic observations from several orbiting low-altitude satellites are contained in this digital collection. Except for MAGSAT, all...

  12. Satellite laser station Helwan status 1992

    Science.gov (United States)

    Cech, M.; Hamal, Karel; Jelinkova, Helena; Novotny, Antonin; Prochazka, Ivan; Baghos, B. B.; Helali, Y.; Tawadros, M. J.

    1993-01-01

    The Satellite Laser Station Helwan has been operated jointly by the National Research Institute of Astronomy and Geophysics in Helwan, Egypt and the Czech Technical University in Prague, Czechslovakia. The station components have been carefully tuned to increase the systems overall stability and reliability critical for the remote location. The mount correction model based on the Gaussian smoothing has been implemented to simplify the blind satellite acquisition and tracking. The on-site normal points generation algorithm has been implemented, the station has been connected to the international information network. The ERS-1 satellite has been included into the tracking schedule. The station range capability has been verified by experimental Etalon 1 ranging by April 1992. The ranging precision of 2-3 centimeters is obtained when ranging to ERS-1, Starlette, and Lageos satellites.

  13. AFSC/ABL: Satellite tagging data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set captures the tag release and timeseries of tracking locations and sensor data associated with each satellite tag that has released. Sablefish, spiny...

  14. Micro Resistojet for Small Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Micro-resistojets offer an excellent combination of simplicity, performance and wet system mass for small satellites (<100 kg, <50 watts) requiring mN level...

  15. Micro Resistojet for Small Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Micro-resistojets offer the best combination of simplicity, performance, wet system mass and power consumption for small satellites (<100kg, <50Watts)...

  16. Software for validating parameters retrieved from satellite

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Sathe, P.V.; Pankajakshan, T.

    efforts to incorporate subroutines to meet every minute requirement. Satellite-sea truth relationships on various space-time window combinations are determined and exhibited in matrix form to visualize the nature of correlation. User has the option...

  17. Satellite imagery and the Department of Safeguards

    International Nuclear Information System (INIS)

    This paper examines the contribution that the Satellite Imagery Analysis Laboratory (SIAL) is making and challenges it faces in supporting Safeguards. Commercial satellite imagery is being utilized as a complementary source of information in the State Evaluation process and under the Strengthened Safeguards regime. Commercial satellite imagery has been embraced by operations and enhanced products that support the inspectorate are now being delivered. These products are a direct result of the integration of different skill-sets, datasets and technology that have taken place under the auspices of a clearly defined and concise analytical process created in the SIAL. This paper will discuss how satellite imagery, its analysis and the fast evolving technology concerned with its use are becoming a fundamental part of an efficient and effective inspection system. (author)

  18. High power communication satellites power systems study

    Science.gov (United States)

    Josloff, Allan T.; Peterson, Jerry R.

    1995-01-01

    This paper discusses a planned study to evaluate the commercial attractiveness of high power communication satellites and assesses the attributes of both conventional photovoltaic and reactor power systems. These high power satellites can play a vital role in assuring availability of universally accessible, wide bandwidth communications, for high definition TV, super computer networks and other services. Satellites are ideally suited to provide the wide bandwidths and data rates required and are unique in the ability to provide services directly to the users. As new or relocated markets arise, satellites offer a flexibility that conventional distribution services cannot match, and it is no longer necessary to be near population centers to take advantage of the telecommunication revolution. The geopolitical implications of these substantially enhanced communications capabilities can be significant.

  19. Future large broadband switched satellite communications networks

    Science.gov (United States)

    Staelin, D. H.; Harvey, R. R.

    1979-01-01

    Critical technical, market, and policy issues relevant to future large broadband switched satellite networks are summarized. Our market projections for the period 1980 to 2000 are compared. Clusters of switched satellites, in lieu of large platforms, etc., are shown to have significant advantages. Analysis of an optimum terrestrial network architecture suggests the proper densities of ground stations and that link reliabilities 99.99% may entail less than a 10% cost premium for diversity protection at 20/30 GHz. These analyses suggest that system costs increase as the 0.6 power of traffic. Cost estimates for nominal 20/30 GHz satellite and ground facilities suggest optimum system configurations might employ satellites with 285 beams, multiple TDMA bands each carrying 256 Mbps, and 16 ft ground station antennas. A nominal development program is outlined.

  20. Electric propulsion for control of stationary satellites

    Energy Technology Data Exchange (ETDEWEB)

    Boucher, Roland

    1963-03-15

    The application of electric propulsion engines to attitude control and stationkeeping of 24-hour stationary satellites is analyzed and compared with the performance of contemporary cold gas, monopropellant, and bipropellant propulsion systems. Both a 500-pound spin-stabilized and a 1500-pound three-axis controlled satellite compatible with current boost vehicles are examined, and each type of propulsion system compared as a function of mission duration and maneuver requirements. Solar electric propulsion is shown to be superior to chemical propulsion for long term stationkeeping and three-axis attitude control of the larger satellite. Cold gas and chemical propulsion are superior for attitude control and provide strong competition for electric propulsion in the stationkeeping of the smaller spin-stabilized satellite. (auth)

  1. Small Satellite Transceiver for Launch Vehicles Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NAL Research Corporation proposes to develop a small, light-weight, low-cost transceivers capable of establishing satellite communications links for telemetry and...

  2. Defense Meteorological Satellite Program (DMSP) Film

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The United States Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) is a polar orbiting meteorological sensor with two...

  3. Reliable multicast transport by satellite: a hybrid satellite/terrestrial solution with erasure codes

    OpenAIRE

    De Belleville, Florestan; Dairaine, Laurent; Lacan, Jérôme; Fraboul, Christian

    2004-01-01

    Geostationary satellites are an efficient way to provide a large scale multipoint communication service. In the context of reliable multicast communications, a new hybrid satellite/terrestrial approach is proposed. It aims at reducing the overall communication cost using satellite broadcasting only when enough receivers are present, and terrestrial transmissions otherwise. This approach has been statistically evaluated for a particular cost function and seems interesting. Then since the hybri...

  4. Satellite laser ranging to GPS and GLONASS

    Science.gov (United States)

    Sośnica, Krzysztof; Thaller, Daniela; Dach, Rolf; Steigenberger, Peter; Beutler, Gerhard; Arnold, Daniel; Jäggi, Adrian

    2015-07-01

    Satellite laser ranging (SLR) to the satellites of the global navigation satellite systems (GNSS) provides substantial and valuable information about the accuracy and quality of GNSS orbits and allows for the SLR-GNSS co-location in space. In the framework of the NAVSTAR-SLR experiment two GPS satellites of Block-IIA were equipped with laser retroreflector arrays (LRAs), whereas all satellites of the GLONASS system are equipped with LRAs in an operational mode. We summarize the outcome of the NAVSTAR-SLR experiment by processing 20 years of SLR observations to GPS and 12 years of SLR observations to GLONASS satellites using the reprocessed microwave orbits provided by the center for orbit determination in Europe (CODE). The dependency of the SLR residuals on the size, shape, and number of corner cubes in LRAs is studied. We show that the mean SLR residuals and the RMS of residuals depend on the coating of the LRAs and the block or type of GNSS satellites. The SLR mean residuals are also a function of the equipment used at SLR stations including the single-photon and multi-photon detection modes. We also show that the SLR observations to GNSS satellites are important to validate GNSS orbits and to assess deficiencies in the solar radiation pressure models. We found that the satellite signature effect, which is defined as a spread of optical pulse signals due to reflection from multiple reflectors, causes the variations of mean SLR residuals of up to 15 mm between the observations at nadir angles of 0 and 14. in case of multi-photon SLR stations. For single-photon SLR stations this effect does not exceed 1 mm. When using the new empirical CODE orbit model (ECOM), the SLR mean residual falls into the range 0.1-1.8 mm for high-performing single-photon SLR stations observing GLONASS-M satellites with uncoated corner cubes. For best-performing multi-photon stations the mean SLR residuals are between and mm due to the satellite signature effect.

  5. Forest inventory improvement based on satellite images

    OpenAIRE

    Jonikavičius, Donatas

    2012-01-01

    The aim of the study – improvement of on-going in Lithuania forest inventories based on satellite images and GIS databases. Specific objective of the study – to explore the possibilities of methods applied for the collection of information from satellite images and GIS databases and its processing in order to determine various Lithuanian forest characteristics, focusing on a variety of forest inventory schemes. 4 The goals of the study: 1. To discuss methodological assumptions for...

  6. Development of a NASA 6-U Satellite

    OpenAIRE

    Thompson, L D

    2011-01-01

    NASA/Wallops Flight Facility has focused on the development of new technologies for the advancement of 6 Unit (6U) small satellites. From the design of the structure and instrument support hardware to improvements in the deployer, NASA is concentrating on maximizing the potential of small satellites for the benefit of science. The telemetry system provides much higher data rates than typical 1U UHF system. 6U provides up to several hundred kilobits per second and utilizes the existing NASA Gr...

  7. Design of a Peruvian Small Satellite Network

    OpenAIRE

    Canales Romero, Juan Martin

    2010-01-01

    A national concept for the implementation of a network of ground stations for small satellite missions is being designed. This network shall support the newly conceived small satellite program in Peru. Currently Peruvian engineers conduct investigations on how to carry out this challenging project, which is expected to gain not only Peru but also the Peruvian industry. The proposed network shall be supported not only by Peruvian government institutions, but also by national and international ...

  8. Satellite Remote Sensing in Seismology. A Review

    Directory of Open Access Journals (Sweden)

    Andrew A. Tronin

    2009-12-01

    Full Text Available A wide range of satellite methods is applied now in seismology. The first applications of satellite data for earthquake exploration were initiated in the ‘70s, when active faults were mapped on satellite images. It was a pure and simple extrapolation of airphoto geological interpretation methods into space. The modern embodiment of this method is alignment analysis. Time series of alignments on the Earth's surface are investigated before and after the earthquake. A further application of satellite data in seismology is related with geophysical methods. Electromagnetic methods have about the same long history of application for seismology. Stable statistical estimations of ionosphere-lithosphere relation were obtained based on satellite ionozonds. The most successful current project "DEMETER" shows impressive results. Satellite thermal infra-red data were applied for earthquake research in the next step. Numerous results have confirmed previous observations of thermal anomalies on the Earth's surface prior to earthquakes. A modern trend is the application of the outgoing long-wave radiation for earthquake research. In ‘80s a new technology—satellite radar interferometry—opened a new page. Spectacular pictures of co-seismic deformations were presented. Current researches are moving in the direction of pre-earthquake deformation detection. GPS technology is also widely used in seismology both for ionosphere sounding and for ground movement detection. Satellite gravimetry has demonstrated its first very impressive results on the example of the catastrophic Indonesian earthquake in 2004. Relatively new applications of remote sensing for seismology as atmospheric sounding, gas observations, and cloud analysis are considered as possible candidates for applications.

  9. Sumatra tsunami affects observations by GRACE satellites

    OpenAIRE

    Bao, L. F; Institute of Geodesy and Geosciences, Chinese Academy od Sciences, Wuhan, China; Piatanesi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Lu, Y.; Institute of Geodesy and Geosciences, Chinese Academy od Sciences, Wuhan, China; Hsu, H. T.; Institute of Geodesy and Geosciences, Chinese Academy od Sciences, Wuhan, China; Zhou, X. H.; Institute of Geodesy and Geosciences, Chinese Academy od Sciences, Wuhan, China

    2005-01-01

    Changes in the Earth’s gravity fi eld are caused by the redistribution of mass within the Earth and on or above its surface.While previous studies [Tapley, 2004; Wahr, 2004] showed that the Gravity Recovery and Climate Experiment (GRACE) satellite mission, executed by NASA,had successfully determined oceanic mass redistribution, the relative motions between two GRACE satellites caused by the 2004 Sumatra tsunami is still uncertain. This present study combines a n...

  10. The Small Astronomy Satellite (SAS) Power Systems

    OpenAIRE

    Sullivan, Ralph

    1987-01-01

    NASA's Small Astronomy Satellites were designed and developed by The Johns Hopkins University's Applied Physics Laboratory for use in the early 1970's. They were Scout launched, spin stabilized satellites intended for a near equatorial, 550 Km, circular orbit. Since the spacecraft were designed so that their spin axis could be pointed in any direction in inertial space, an omnidirectional solar cell array was required. An additional significant constraint on the solar cell array design was th...

  11. Satellite altimeter remote sensing of ice caps

    OpenAIRE

    Rinne, Eero Juhani

    2011-01-01

    This thesis investigates the use of satellite altimetry techniques for measuring surface elevation changes of ice caps. Two satellite altimeters, Radar Altimeter 2 (RA-2) and Geoscience Laser Altimeter System (GLAS) are used to assess the surface elevation changes of three Arctic ice caps. This is the first time the RA-2 has been used to assess the elevation changes of ice caps - targets much smaller than the ice sheets which are the instrument’s primary land ice targets. Algor...

  12. High Precision Orbit Determination of CHAMP Satellite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qile; LIU Jingnan; GE Maorong

    2006-01-01

    The precision orbit determination of challenging minisatellite payload(CHAMP) satellite was done based on position and navigation data analyst(PANDA) software which is developed in Wuhan University, using the onboard GPS data of year 2002 from day 126 to 131. The orbit accuracy was assessed by analyzing the difference from GFZ post-processed science orbits (PSO), the GPS carrier and pseudo-range data residuals and the satellite laser ranging (SLR) residuals.

  13. Communication satellites: Guidelines for a strategic plan

    Science.gov (United States)

    1987-01-01

    To maintain and augment the leadership that the United States has enjoyed and to ensure that the nation is investing sufficiently and wisely to this purpose, a strategic plan for satellite communications research and development was prepared by NASA. Guidelines and recommendations for a NASA plan to support this objective and for the conduct of communication satellite research and development program over the next 25 years were generated. The guidelines are briefly summarized.

  14. Astrometry and Geostationary Satellites in Venezuela

    Science.gov (United States)

    Lacruz, E.; Abad, C.

    2015-10-01

    We present the current status and the first results of the astrometric project CIDA - ABAE for tracking geo-stationary satellites. This project aims to determine a preliminary orbit for the Venezuelan satellite VENESAT-1, using astrometric positions obtained from an optical telescope. The results presented here are based on observations from the Luepa space tracking ground station in Venezuela, which were processed using astrometric procedures.

  15. Satellite Attitude Control Using Only Electromagnetic Actuation

    OpenAIRE

    Wisniewski, Rafal

    1997-01-01

    The primary purpose of this work was to develop control laws for three axis stabilization of a magnetic actuated satellite. This was achieved by a combination of linear and nonlinear system theory. In order to reach this goal new theoretical results were produced in both fields. The focus of the work was on the class of periodic systems reflecting orbital motion of the satellite. In addition to a theoretical treatment, the thesis contains a large portion of application considerations. The con...

  16. Saturn satellites as seen by Cassini Mission

    OpenAIRE

    Coradini, A; Capaccioni, F.; Cerroni, P.; Filacchione, G.; Magni, G; Orosei, R.; F. Tosi; Turrini, D

    2009-01-01

    In this paper we will summarize some of the most important results of the Cassini mission concerning the satellites of Saturn. Given the long duration of the mission, the complexity of the payload onboard the Cassini Orbiter and the amount of data gathered on the satellites of Saturn, it would be impossible to describe all the new discoveries made, therefore we will describe only some selected, paramount examples showing how Cassini's data confirmed and extended ground-based observations. In ...

  17. Discovery of a new Jupiter satellite

    Science.gov (United States)

    Jewitt, D. C.; Danielson, G. E.; Synnott, S. P.

    1979-01-01

    During detailed analysis of Voyager 2 pictures of the Jupiter ring, a starlike object was identified in the plane of the ring. The same object was subsequently found on a higher-resolution frame and proved to be a satellite of Jupiter. This satellite has a circular orbit whose radius is 1.8 Jupiter radii, a period of 7 hours and 8 minutes, and a diameter of less than 40 kilometers. It is located at the outer edge of the Jupiter ring.

  18. Managing Mobile/Satellite Propagation Data

    Science.gov (United States)

    Kantak, Anil V.

    1990-01-01

    "Data Management System for Mobile Satellite Propagation" software package collection of FORTRAN programs and UNIX shell scripts designed to handle huge amounts of data resulting from mobile/satellite radio-propagation experiments. Data from experiments converted into standard and more useful forms. Software package contains program to convert binary format of data into standard ASCII format suitable for use with wide variety of computing-machine architectures. Written in either FORTRAN 77 or UNIX shell scripts.

  19. Satellite image classification using convolutional learning

    Science.gov (United States)

    Nguyen, Thao; Han, Jiho; Park, Dong-Chul

    2013-10-01

    A satellite image classification method using Convolutional Neural Network (CNN) architecture is proposed in this paper. As a special case of deep learning, CNN classifies classes of images without any feature extraction step while other existing classification methods utilize rather complex feature extraction processes. Experiments on a set of satellite image data and the preliminary results show that the proposed classification method can be a promising alternative over existing feature extraction-based schemes in terms of classification accuracy and classification speed.

  20. Extrapolating Satellite Winds to Turbine Operating Heights

    OpenAIRE

    Badger, Merete; Pena Diaz, Alfredo; Hahmann, Andrea N.; Mouche, Alexis; Hasager, Charlotte Bay

    2016-01-01

    Ocean wind retrievals from satellite sensors are typically performed for the standard level of 10 m. This restricts their full exploitation for wind energy planning, which requires wind information at much higher levels where wind turbines operate. A new method is presented for the vertical extrapolation of satellitebased wind maps. Winds near the sea surface are obtained from satellite data and used together with an adaptation of the Monin–Obukhov similarity theory to estimate the wind speed...

  1. International Surveillance Satellites - Open Skies for All?

    OpenAIRE

    Johan Swahn

    1988-01-01

    Since the early 1960s the US and the USSR have had a monopoly on highly detailed surveillance information gathered from satellites in orbits around the Earth. The information available from these satellites has created a situation of open skies between the superpowers. Insight into the other side's military activities has facilitated limited arms control results and stabilized crises While there are confidence-building advantages in this situation there are drawbacks to the monopoly Outside p...

  2. Hydrogen Peroxide Propulsion for Smaller Satellites

    OpenAIRE

    Whitehead, John

    1998-01-01

    As satellite designs shrink, providing maneuvering and control capability falls outside the realm of available propulsion technology. While cold gas has been used on the smallest satellites, hydrogen peroxide propellant is suggested as the next step in performance and cost before hydrazine. Minimal toxicity and a small scale enable bench top propellant preparation and development testing. Progress toward low-cost thrusters and self-pressurizing tank systems is described.

  3. Modeling and Control of SPIDER Satellite Components

    OpenAIRE

    Ruggiero, Eric John

    2005-01-01

    Space satellite technology is heading in the direction of ultra-large, lightweight structures deployable on orbit. Minimal structural mass translates into minimal launch costs, while increased satellite bus size translates into significant bandwidth improvement for both radar and optical applications. However, from a structural standpoint, these two goals are in direct conflict with one another, as large, flexible structures possess terrible dynamic properties and minimal effective bandwidt...

  4. Network Coded Multicast over Multibeam Satellite Systems

    OpenAIRE

    R. Alegre-Godoy; Vazquez-Castro, M. A.

    2015-01-01

    We propose a multicast scheme for multibeam satellite systems exploiting both the multiuser and spatial diversity inherent in this type of systems while taking into account realistic physical distributions of User Terminals (UTs) over the coverage. Our proposed scheme makes use of the well-known Adaptive Coding and Modulation (ACM) feature in Digital Video Broadcasting over Satellite, 2nd Generation (DVB-S2) and Extension (DVB-S2X) standards but also incorporates a set of innovative features....

  5. Chinese Satellites Serve Beijing Olympic Games

    Institute of Scientific and Technical Information of China (English)

    Ren Shufang

    2008-01-01

    @@ METEOROLOGICAL SATELLITES PROVIDING WEATHER SERVICES As the opening and closing ceremonies and many competition events such as athletics, football, cycling and sailing etc., were held in open air stadiums, field or on water, it was of great importance to provide exact weather forecasts and on-time climate information to prepare for disastrous weather so as to ensure the Olympic Games proceeded smoothly. For this purpose, China launched the meteorological satellite service project in 2002 to safeguard the 2008 Beijing Olympic Games.

  6. Refinement of the gravity field by satellite-to-satellite Doppler tracking.

    Science.gov (United States)

    Schwarz, C. R.

    1972-01-01

    The question of what resolution of the gravity field can be obtained from satellite-to-satellite Doppler tracking was investigated by performing least-squares adjustments of simulated Doppler data, solving for parameters describing the anomalous gravity field in various sized blocks. By examining the correlation between the adjusted parameters describing neighboring blocks, it was possible to judge whether a given set of data was capable of resolving blocks of a given size. Two concepts of satellite-to-satellite tracking are considered: the first involves two satellites near together in very low orbits, while the second uses geostationary satellites to track a single very low satellite. In either case, blocks 500 km on a side can be satisfactorily resolved from an orbital altitude of 700 km. From an altitude of 200 km, blocks 200 km on a side can be resolved. Because of the lower limit on altitude imposed by the presence of the earth's atmosphere, it does not appear that satellite-to-satellite Doppler tracking will be able to resolve features smaller than 200 km on a side.

  7. Solar power satellites: The Engineering Challenges

    Science.gov (United States)

    Woodcock, G. R.

    1978-01-01

    Certain elements of solar power satellite design and system engineering studies are reviewed analyzing solar power satellites as a potential baseload electric power source. The complete system concept concept includes not only the satellites and their ground stations, but also the space transportation for delivery of the satellites, piece by piece, into space, and the factories for their construction in space. Issues related to carrying the solar power satellite concept from the present design study phase through implementation of actual hardware are considered. The first issue category is environmental aspects of the SPS systems. The second category of issues is the technology risks associated with achieving the necessary component and subsystem performances. The third category includes the engineering issues associated with carrying out such a large scale project. The fourth issue category is financial: the funding required to bring such a project into being and the costs of the satellites and resulting cost of the power produced as compared to potential alternative energy sources.

  8. Power versus stabilization for laser satellite communication.

    Science.gov (United States)

    Arnon, S

    1999-05-20

    To establish optical communication between any two satellites, the lines of sight of their optics must be aligned for the duration of the communication. The satellite pointing and tracking systems perform the alignment. The satellite pointing systems vibrate because of tracking noise and mechanical impacts (such as thruster operation, the antenna pointing mechanism, the solar array driver, navigation noise, tracking noise). These vibrations increase the bit error rate (BER) of the communication system. An expression is derived for adaptive transmitter power that compensates for vibration effects in heterodyne laser satellite links. This compensation makes it possible to keep the link BER performance constant for changes in vibration amplitudes. The motivation for constant BER is derived from the requirement for future satellite communication networks with high quality of service. A practical situation of a two-low-Earth-orbit satellite communication link is given. From the results of the example it is seen that the required power for a given BER increases almost exponentially for linear increase in vibration amplitude. PMID:18319913

  9. Formation and evolution of Pluto's small satellites

    CERN Document Server

    Walsh, Kevin J

    2015-01-01

    Pluto's system of 5 known satellites are in a puzzling orbital configuration. Each of the four small satellites are on low-eccentricity and low-inclination orbits situated near a mean motion resonance with the largest satellite Charon. The Pluto-Charon binary likely formed as a result of a giant impact and so the simplest explanation for the small satellites is that they accreted from debris of that collision. The Pluto-Charon binary has evolved outward since its formation due to tidal forces, which drove them into their current doubly synchronous state. Meanwhile, leftover debris from the formation of Charon was not initially distant enough from Pluto-Charon to explain the orbits of the current small satellites. The outstanding problems of the system are the movement of debris outward and the small satellites location near mean motion resonances with Charon. This work explores the dynamical behavior of collisionally interacting debris orbiting the Pluto-Charon system. While this work specifically tests initi...

  10. The reionization of galactic satellite populations

    Energy Technology Data Exchange (ETDEWEB)

    Ocvirk, P.; Gillet, N.; Aubert, D.; Chardin, J. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); Knebe, A.; Yepes, G. [Grupo de Astrofísica, Departamento de Fisica Teorica, Modulo C-8, Universidad Autónoma de Madrid, Cantoblanco E-280049 (Spain); Libeskind, N.; Gottlöber, S. [Leibniz-Institute für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Hoffman, Y. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

    2014-10-10

    We use high-resolution simulations of the formation of the local group, post-processed by a radiative transfer code for UV photons, to investigate the reionization of the satellite populations of an isolated Milky Way-M31 galaxy pair in a variety of scenarios. We use an improved version of ATON which includes a simple recipe for radiative feedback. In our baseline models, reionization is initiated by low-mass, radiatively regulated halos at high redshift, until more massive halos appear, which then dominate and complete the reionization process. We investigate the relation between reionization history and present-day positions of the satellite population. We find that the average reionization redshift (z {sub r}) of satellites is higher near galaxy centers (MW and M31). This is due to the inside out reionization patterns imprinted by massive halos within the progenitor during the epoch of reionization, which end up forming the center of the galaxy. Due to incomplete dynamical mixing during galaxy assembly, these early patterns survive to present day, resulting in a clear radial gradient in the average satellite reionization redshift, up to the virial radius of MW and M31 and beyond. In the lowest emissivity scenario, the outer satellites are reionized about 180 Myr later than the inner satellites. This delay decreases with increasing source model emissivity, or in the case of external reionization by Virgo or M31, because reionization occurs faster overall and becomes spatially quasi-uniform at the highest emissivity.

  11. Satellites and Haloes of Dwarf Galaxies

    CERN Document Server

    Sales, Laura V; White, Simon D M; Navarro, Julio F

    2012-01-01

    We study the abundance of satellite galaxies as a function of primary stellar mass using the SDSS/DR7 spectroscopic catalogue. In contrast with previous studies, which focussed mainly on bright primaries, our central galaxies span a wide range of stellar mass, 10^7.5 < M_*^pri/M_sun < 10^11, from dwarfs to central cluster galaxies. Our analysis confirms that the average number of satellites around bright primaries, when expressed in terms of satellite-to-primary stellar mass ratio (m_*^sat/M_*^pri), is a strong function of M_*^pri. On the other hand, satellite abundance is largely independent of primary mass for dwarf primaries (M_*^pri<10^10 M_sun). These results are consistent with galaxy formation models in the LCDM scenario. We find excellent agreement between SDSS data and semi-analytic mock galaxy catalogues constructed from the Millennium-II Simulation. Satellite galaxies trace dark matter substructure in LCDM, so satellite abundance reflects the dependence on halo mass, M_200, of both substru...

  12. Capture of irregular satellites at Jupiter

    International Nuclear Information System (INIS)

    The irregular satellites of outer planets are thought to have been captured from heliocentric orbits. The exact nature of the capture process, however, remains uncertain. We examine the possibility that irregular satellites were captured from the planetesimal disk during the early solar system instability when encounters between the outer planets occurred. Nesvorný et al. already showed that the irregular satellites of Saturn, Uranus, and Neptune were plausibly captured during planetary encounters. Here we find that the current instability models present favorable conditions for capture of irregular satellites at Jupiter as well, mainly because Jupiter undergoes a phase of close encounters with an ice giant. We show that the orbital distribution of bodies captured during planetary encounters provides a good match to the observed distribution of irregular satellites at Jupiter. The capture efficiency for each particle in the original transplanetary disk is found to be (1.3-3.6) × 10–8. This is roughly enough to explain the observed population of jovian irregular moons. We also confirm Nesvorný et al.'s results for the irregular satellites of Saturn, Uranus, and Neptune.

  13. Pattern dependent satellite defects in via lithography

    Science.gov (United States)

    Yu, Chih-Chieh; Yang, Mars; Yang, Elvis; Yang, T. H.; Chen, K. C.; Lu, Chih-Yuan

    2012-03-01

    In patterning the via-hole, uneven hole-size and missing-hole defects were identified through after etch inspection (AEI), and these defects were characterized as yield killer since it led to electrical open. Through the after development inspection (ADI) and AEI comparison, the uneven hole-size and missing-hole defects are attributed to the postdeveloped satellite spots. The distribution of satellite spots always show a strong photo field map that is discovered to correlate with the local pattern density in mask scribe lane. Apart from the possible modifications on pattern density in the scribe lane by retooling the photo mask, this paper describes the work done in reducing the satellite defect. Several development experiments including multiple wafer agitation cycles of dynamic puddle, multiple cycles of scanning rinse, pre-wet before development, wafer rotation speed in rinse, wafer rotation speed in drying and advanced defect reduction (ADR) function of track were carried out. The multiple cycles of scanning rinse coupling with the optimal wafer rotation speed of rinse effectively suppresses the count of satellite spots. Pre spin dry in advance of the deionized water (DIW) rinse to minimize the pH shock is also effective to reduce the defect count. Multiple cycles of development puddle and scanning rinse have a synergy effect to lower defectivity up to complete suppression of satellite defect. To minimize the throughput loss induced by the long development time, ADR is proposed as better candidate for fully eliminating the satellite defect.

  14. The reionization of galactic satellite populations

    International Nuclear Information System (INIS)

    We use high-resolution simulations of the formation of the local group, post-processed by a radiative transfer code for UV photons, to investigate the reionization of the satellite populations of an isolated Milky Way-M31 galaxy pair in a variety of scenarios. We use an improved version of ATON which includes a simple recipe for radiative feedback. In our baseline models, reionization is initiated by low-mass, radiatively regulated halos at high redshift, until more massive halos appear, which then dominate and complete the reionization process. We investigate the relation between reionization history and present-day positions of the satellite population. We find that the average reionization redshift (z r) of satellites is higher near galaxy centers (MW and M31). This is due to the inside out reionization patterns imprinted by massive halos within the progenitor during the epoch of reionization, which end up forming the center of the galaxy. Due to incomplete dynamical mixing during galaxy assembly, these early patterns survive to present day, resulting in a clear radial gradient in the average satellite reionization redshift, up to the virial radius of MW and M31 and beyond. In the lowest emissivity scenario, the outer satellites are reionized about 180 Myr later than the inner satellites. This delay decreases with increasing source model emissivity, or in the case of external reionization by Virgo or M31, because reionization occurs faster overall and becomes spatially quasi-uniform at the highest emissivity.

  15. The Air Density Explorer Satellite Program

    Science.gov (United States)

    Keating, G. M.; Prior, E. J.

    1973-01-01

    Since 1961, four satellites designed specifically for determination of the density and composition variations of the earth's neutral atmosphere at satellite altitudes have been launched: Explorer 9, Explorer 19, Explorer 24, and Explorer 39. Studies of the orbital decay of these satellites have resulted in major revisions in our conception of the upper atmosphere at satellite altitudes. These features include the winter helium bulge detected near 1000 km with its north-south asymmetry, the summer atomic oxygen bulge near 500 km, and the winter enhancement of atomic oxygen near 120 km. The Langley Research Center is now in the process of designing and fabricating the Dual Air Density Explorers. These will be two satellites launched by means of a single Scout rocket in 1975, and they are expected to remain in essentially the same orbital plane throughout the 2-year mission. Each satellite is drag sensitive and uses a mass spectrometer in a unique system which is insensitive to orientation, is highly sensitive to the upper atmosphere, and is capable of in-flight calibration.

  16. Capture of irregular satellites at Jupiter

    Energy Technology Data Exchange (ETDEWEB)

    Nesvorný, David; Vokrouhlický, David; Deienno, Rogerio [Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States)

    2014-03-20

    The irregular satellites of outer planets are thought to have been captured from heliocentric orbits. The exact nature of the capture process, however, remains uncertain. We examine the possibility that irregular satellites were captured from the planetesimal disk during the early solar system instability when encounters between the outer planets occurred. Nesvorný et al. already showed that the irregular satellites of Saturn, Uranus, and Neptune were plausibly captured during planetary encounters. Here we find that the current instability models present favorable conditions for capture of irregular satellites at Jupiter as well, mainly because Jupiter undergoes a phase of close encounters with an ice giant. We show that the orbital distribution of bodies captured during planetary encounters provides a good match to the observed distribution of irregular satellites at Jupiter. The capture efficiency for each particle in the original transplanetary disk is found to be (1.3-3.6) × 10{sup –8}. This is roughly enough to explain the observed population of jovian irregular moons. We also confirm Nesvorný et al.'s results for the irregular satellites of Saturn, Uranus, and Neptune.

  17. Lorentz Force Based Satellite Attitude Control

    Science.gov (United States)

    Giri, Dipak Kumar; Sinha, Manoranjan

    2016-07-01

    Since the inception of attitude control of a satellite, various active and passive control strategies have been developed. These include using thrusters, momentum wheels, control moment gyros and magnetic torquers. In this present work, a new technique named Lorentz force based Coulombic actuators for the active control is proposed. This method uses electrostatic charged shells, which interact with the time varying earth's magnetic field to establish a full three axes control of the satellite. It is shown that the proposed actuation mechanism is similar to a satellite actuated by magnetic coils except that the resultant magnetic moment vanishes under two different conditions. The equation for the required charges on the the Coulomb shells attached to the satellite body axes is derived, which is in turn used to find the available control torque for actuating the satellite along the orbit. Stability of the proposed system for very high initial angular velocity and exponential stability about the origin are proved for a proportional-differential control input. Simulations are carried out to show the efficacy of the proposed system for the attitude control of the earth-pointing satellite.

  18. 47 CFR 25.279 - Inter-satellite service.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Inter-satellite service. 25.279 Section 25.279 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.279 Inter-satellite service. (a) Any satellite communicating with other...

  19. Plan of advanced satellite communication experiments using ETS-6

    Science.gov (United States)

    Ikegami, Tetsushi

    1989-01-01

    In 1992, an Engineering Test Satellite 6 is scheduled to be launched by an H-2 rocket. The missions of ETS-6 are to establish basic technologies of inter-satellite communications using S-band, millimeter waves and optical beams and of fixed and mobile satellite communications using multibeam antenna on board the satellite. A plan of the experiments is introduced.

  20. A preliminary study on dead geostationary satellite removal

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The collision between satellites IRIDIUM 33 and COSMOS 2251 indicated that the clash of two on-orbit satellites was becoming an inevitable reality. Our calculation with the two-line orbit element by NORAD showed that some two geostationary satellites had approached very close in July 2009. Therefore, more attention should be given to avoid such collisions. This paper analyzes the orbital long-term variation of a dead satellite drifting in the geostationary orbit. Also, the negative effects posed by dead satellites upon the on-orbit operational geostationary satellites are studied. Then the paper proposes a novel idea to launch a satellite sweeper whose purpose is to collect the on-orbit dead satellites and help them de-orbit to a "graveyard". The satellite sweeper consists of a parent satellite and a child satellite. The child satellite collects a dead satellite and transfers it to a higher orbit. The parent satellite stationed in the geostationary orbit is in charge of refueling the child satellite. The strategy of maneuver and rendezvous is presented and a series of formulas are derived. The analysis results show that our method to clean the geostationary orbital zone is practical and fuel-saving. With the help of just a few satellite sweepers, we can gain a clean environment of geostationary orbit environment again.

  1. Software Defined Networking and Virtualization for Broadband Satellite Networks

    OpenAIRE

    Bertaux, Lionel; Medjiah, Samir; Berthou, Pascal; Abdellatif, Slim; Hakiri, Akram; Gelard, Patrick; Planchou, Fabrice; De Bruyère, Marc

    2015-01-01

    Satellite networks have traditionally been considered for specific purposes. Recently, new satellite technologies have been pushed to the market enabling high-performance satellite access networks. On the other hand, network architectures are taking advantages from emerging technologies such as Software-Defined Networking (SDN), network virtualization and Network Functions Virtualization (NFV). Therefore, benefiting communications services over satellite networks from these new technologies a...

  2. Using satellite communications for a mobile computer network

    Science.gov (United States)

    Wyman, Douglas J.

    1993-01-01

    The topics discussed include the following: patrol car automation, mobile computer network, network requirements, network design overview, MCN mobile network software, MCN hub operation, mobile satellite software, hub satellite software, the benefits of patrol car automation, the benefits of satellite mobile computing, and national law enforcement satellite.

  3. Satellite Imaging in the Study of Pennsylvania's Environmental Issues.

    Science.gov (United States)

    Nous, Albert P.

    This document focuses on using satellite images from space in the classroom. There are two types of environmental satellites routinely broadcasting: (1) Polar-Orbiting Operational Environmental Satellites (POES), and (2) Geostationary Operational Environmental Satellites (GOES). Imaging and visualization techniques provide students with a better…

  4. Weather Prediction Improvement Using Advanced Satellite Technology

    Science.gov (United States)

    Einaudi, Franco; Uccellini, L.; Purdom, J.; Rogers, D.; Gelaro, R.; Dodge, J.; Atlas, R.; Lord, S.

    2001-01-01

    We discuss in this paper some of the problems that exist today in the fall utilization of satellite data to improve weather forecasts and we propose specific recommendations to solve them. This discussion can be viewed as an aspect of the general debate on how best to organize the transition from research to operational satellites and how to evaluate the impact of a research instrument on numerical weather predictions. A method for providing this transition is offered by the National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP). This mission will bridge the time between the present NOAA and Department of Defense (DOD) polar orbiting missions and the initiation of the converged NPOESS series and will evaluate some of the Earth Observing System (EOS) instruments as appropriate for operational missions. Thus, this mission can be viewed as an effort to meet the operational requirements of NOAA and DOD and the research requirements of NASA. More generally, however, it can be said that the process of going from the conception of new, more advanced instruments to their operational implementation and full utilization by the weather forecast communities is not optimal. Instruments developed for research purposes may have insufficient funding to explore their potential operational capabilities. Furthermore, instrument development programs designed for operational satellites typically have insufficient funding for assimilation algorithms needed to transform the satellite observations into data that can be used by sophisticated global weather forecast models. As a result, years often go by before satellite data are efficiently used for operational forecasts. NASA and NOAA each have unique expertise in the design of satellite instruments, their use for basic and applied research and their utilization in weather and climate research. At a time of limited resources, the two agencies must combine their efforts to work toward common

  5. Satellite virtual atomic clock with pseudorange difference function

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Satellite atomic clocks are the basis of GPS for the control of time and frequency of navigation signals. In the Chinese Area Positioning System (CAPS), a satellite navigation system without the satellite atomic clocks onboard is successfully developed. Thus, the method of time synchronization based on satellite atomic clocks in GPS is not suitable. Satellite virtual atomic clocks are used to implement satellite navigation. With the satellite virtual atomic clocks, the time at which the signals are transmitted from the ground can be delayed into the time that the signals are transmitted from the satellites and the pseudorange measuring can be fulfilled as in GPS. Satellite virtual atomic clocks can implement the navigation, make a pseudorange difference, remove the ephemeris error, and improve the accuracy of navigation positioning. They not only provide a navigation system without satellite clocks, but also a navigation system with pseudorange difference.

  6. Performance Analysis of BDS Satellite Orbits during Eclipse Periods: Results of Satellite Laser Ranging Validation

    Directory of Open Access Journals (Sweden)

    PENG Hanbing

    2016-06-01

    Full Text Available The performance of BeiDou satellite orbits during eclipse periods is an important part of the performance analysis of BeiDou Navigation Satellite System (BDS. Accuracy evaluation of satellite orbits in ephemeris of BDS during eclipse periods can provide support for the service performance assessment. It also helps to find possible deficiencies in the orbit modeling during eclipse periods, which may further contribute to the improvements of functional models for precise orbit determination. The effects of eclipse periods on the orbits of the three types of satellites of BDS are analyzed with the satellite laser ranging (SLR observations ranging from January 2014 to July 2015. At the same time, the orbit radial accuracy of BDS broadcast and precise ephemeris are validated. The results show that, obvious orbit accuracy decrease can be observed in both broadcast and precise ephemeris for IGSO/MEO satellites during eclipse periods (especially the yaw-maneuver periods. And orbit radial errors of IGSO/MEO satellites in broadcast ephemeris reach 1.5~2.0 m, and exceed 10.0 cm for that in precise ephemeris. Performance decrease of the GEO satellite orbit during eclipse arcs can hardly be revealed by the orbit radial residual series. During non-eclipse periods, radial accuracy of IGSO/MEO and GEO satellite orbits in broadcast ephemeris are better than 0.5 m and 0.9 m respectively. The radial accuracy of IGSO/MEO satellite orbits in precise ephemeris are better than 10.0 cm and that of the GEO satellite is about 50.0 cm with a systematic bias of 40.0 cm around.

  7. Planets and satellites: tectonic twins

    Science.gov (United States)

    Kochemasov, G. G.

    2015-10-01

    There are only three solid planet-satellite pairs in the Solar system: Earth -Moon, Mars -Phobos, Pluto - Charon. For the first two pairs tectonic analogies were shown and explained by moving them in one circumsolar orbit. As it is known from the wave planetology [3, 4, 6], "orbits make structures". For the third pair the same was stated as a prediction based on this fundamental rule. Global tectonic forms of wave origin appear in cosmic bodies because they move in keplerian orbits with periodically changing accelerations. Warping bodies waves have a stationary character and obeying wave harmonics lengths. Starting from the fundamental 2πR-long wave 1 making the ubiquitous tectonic dichotomy (two-face appearance) warping wave lengths descend along harmonics. Very prominent along with the wave 1 are waves 2 responsible for tectonic sectoring superimposed on the wave 1 segments. Practically all bodies have traces of shorter waves making numerous polygons (rings) often confused with impact craters. Earth and the Moon moving in one circumsolar orbit both are distorted by wave 1, wave 2 and wave 4 features aligned along extent tectonic lines [4, 5]. At Earth they are: Pacific Ocean (2πR-structure) and Indian Ocean (πR-structure) from both ends with Malay Archipelago (πR/4-structure) in the middle. At Moon they are: Procellarum Ocean (2πR) and SPA Basin (πR) from ends and Mare Orientale (πR/4) in the middle. A regular disposition is surprising. Both Oceans and Basin occur on opposite hemispheres, lying in the middle both ring structures occur in the boundary between two hemispheres and are of the same relative size. These triads stretch along lines parallel to the equator (Earth) and with the angle about 30 degrees to it (Moon) indicating at a different orientation of the rotation axes in the ancient time [2]. On the whole, one could speak about a "lunar mould" of Earth [5] (Fig. 1-3). Another tectonic twin is the pair Mars -Phobos. Both bodies sharing one

  8. The escape of natural satellites from Mercury and Venus

    International Nuclear Information System (INIS)

    It is suggested that the slow rotations of Mercury and Venus may be connected with the absence of natural satellites around them. If Mercury or Venus possessed a satellite at the time of formation, the tidal evolution would have caused the satellite to recede. At a sufficiently large distance from the planet, the Sun's gravitational influence makes the satellite orbit unstable. The natural satellites of Mercury and Venus might have escaped as a consequence of this instability. (Auth.)

  9. Spaceborne Fiber-Optic Data Bus: A Small Satellite Perspective

    OpenAIRE

    Rider, Dustin; Orlando, Fred

    2007-01-01

    Small-satellite system developers are poised to benefit from yet another technology that was developed with large satellites in mind: standards-based, broadband, on-board payload data networks. Large and small remote-sensing satellite payloads are continuing to advance to higher data rates thereby significantly increasing the demands on on-board networks. The networked satellite payloads include combinations of components commonly found on small satellites: sensors, processors, formatters, st...

  10. The Demeter micro satellite launch campaign

    Science.gov (United States)

    Dubourg, V.; Kainov, V.; Thoby, M.; Silkin, O.; Solovey, V.

    The CNES Micro satellite DEMETER is planned for launch by the end of June 2004 on a DNEPR launcher, from the Baíkonur cosmodrome. DEMETER will be the main payload among nine co-passengers. DEMETER, initiated by CNES in 1998, is the first model of the MYRIADE micro satellites line of product; at the time when this abstract is issued, the satellite is going through the final integration tests, as well as the last system validation phase. The space head module of the launcher has been developed by the Ukrainian YSDO company, and a successful fit check test campaign has been performed in December 2003 and January 2004 that allowed confirming the compatibility of the payloads with their launcher interface. The launch campaign is in process of preparation, implying a close partnership between the satellite team at CNES and Russian and Ukrainian launcher authorities: DEMETER is a pioneer not only for the satellite concept itself, but also for being the first satellite of this range (3 axis stabilized, including an hydrazine propulsion system and developed by a national space agency) being launched on a Russian space adapted intercontinental ballistic missile SS18. The launch service is contracted and managed by ISC Kosmotras, and it will also be the first sun synchronous orbit launch for DNEPR. Thus the launch preparation proved to be a very challenging endeavour providing all the actors with very rich human experience, as well as technical exchanges, in the fields of launcher technology and interfaces, facilities adaptation, logistics and project coordination. In the coming paper, a short presentation of the DEMETER satellite and of the DNEPR launcher will be made, but the main purpose is to present: the launch campaign preparation milestones, the launch campaign itself and related preliminary results and the lessons learnt from this first CNES/DNEPR experience to open the way to the future MYRIADE launches. A common CNES/KOSMOTRAS presentation is proposed at the

  11. Multicolour Optical Photometry of Active Geostationary Satellites

    Science.gov (United States)

    Jolley, A.; Wade, G.; Bedard, D.

    Although broadband photometry has been used to infer information about artificial satellites since soon after the launch of Sputnik 1, the development of photometric techniques for non-resolved space object identification or characterisation has been hampered by the large number of variables involved. Many individual studies, and some long ongoing experiments, have used costly metre-class telescopes to obtain data despite other experiments demonstrating that much more flexible and affordable small aperture telescopes may be suitable for the task. In addition, due to the highly time consuming and weather dependent nature of obtaining photometric observations, many studies have suffered from data sets of limited size, or relied upon simulations to support their claims. With this in mind, an experiment was conducted with the aim of determining the utility of small aperture telescopes for conducting broadband photometry of satellites for the purpose of non-resolved space object identification and characterisation. A 14 inch Celestron CG-14 telescope was used to gain multiple night-long, high temporal resolution data sets of six active geostationary satellites. The results of the experiment cast doubt on the efficacy of some of the previous approaches to obtaining and analysing photometric data. It was discovered that geostationary satellite lightcurves can vary to a greater degree than has generally been recognised, and colour ratios vary considerably with changes in the illumination/observation geometry, making it difficult to use colour for satellite discrimination. Evidence was also detected of variations in the spectral energy distribution of sunlight reflected off satellite surface materials, which could have implications for surface material characterisation and techniques that aim to separate satellite body and solar panel contributions to the total observed spectra.

  12. Overview of the Ocean Observer Satellite Study

    Science.gov (United States)

    Cunningham, J. D.; McGuire, J. P.; Pichel, W. G.; Gerber, A. J.

    2002-12-01

    A two-year study of ocean satellite remote sensing requirements and instrument/satellite options is nearing completion. This Ocean Observer Study was sponsored by the U.S. Dept. of Commerce/Dept. of Defense/National Aeronautics and Space Administration Integrated Program Office, whose mission is to develop the future U.S. National Polar-Orbiting Operational Environmental Satellite System (NPOESS). A comprehensive Ocean Observer User Requirements Document has been drafted by a team of over 150 government, academic, and private sector scientists, engineers, and administrators. Included are requirements for open and coastal ocean surface, cryospheric, hydrologic, and some land/hazard and atmospheric boundary layer parameters. This document was then used as input to the instrument and satellite study (conducted by the Jet Propulsion Laboratory) which produced five different instrument/satellite configuration options designed to address the maximum number of requirements which will not be met with the already-approved NPOESS instruments. Instruments studied include a synthetic aperture radar (SAR), an altimeter, and a hyper-spectral coastal infrared/visible imager. After analyzing the alternatives, it appears that one of the best options is a two-satellite system consisting of (1) an altimeter mission in the Topex/Poseidon orbit carrying both wide-swath and delayed doppler altimeters, and (2) a multi-polarization, multi-frequency, multi-mode interferometric SAR mission including a coastal imager in a polar sun-synchronous orbit. This paper summarizes the user requirements process, briefly describes the notional satellite configuration, and presents some of the capabilities of the instruments.

  13. Satellite data-relay activities in Arizona

    Science.gov (United States)

    Boner, F.C.; Blee, J.W.; Shope, W.G.

    1985-01-01

    The U.S. Geological Survey (USGS) Arizona District collects data from automated streamflow stations for a wide variety of uses. Data from these stations are provided to Federal, State, and local agencies that have a responsibility to issue flood warnings; to generate forecasts of water availability; to monitor flow to insure compliance with treaties and other legal mandates; and to manage reservoirs for hydropower, flood abatement, and municipal and irrigation water supply. In the mid-1970's, the escalation of data collection costs and a need for more timely data led the Arizona District to examine alternatives for remote data acquisition. On the basis of successful data communications experiments with NASA 's Landsat satellite, an operational system for satellite-data relay was developed in 1976 using the National Oceanic and Atmospheric Administrations 's (NOAA) Geostationary Operational Environmental Satellite (GOES). A total of 62 data collection platforms (DCP's) was operated in 1983. Satellite telemetry operations are controlled at the remote data-collection stations by small battery-operated data collection platforms. The DCP 's periodically collect data from the sensors, store the data in computer memory, and at preset times transmit the data to the GOES satellite. The satellite retransmits the data to Earth where a ground-receive station transmits or transfers the data by land communications to the USGS computer in Reston, Virginia, for processing. The satellite relay transfers the data from sensor to computer in minutes; therefore, the data are available to users on a near real-time basis. (Author 's abstract)

  14. Proposed Nomenclature for Surface Features on Pluto and Its Satellites and Names for Newly Discovered Satellites

    OpenAIRE

    Mamajek, Eric E.; Rapson, Valerie A.; Cameron, David A; Olmedo, Manuel; Fogerty, Shane; Franklin, Eric; Lambrides, Erini; Hasan, Imran; Sarkis, Richard E.; Thorndike, Stephen; Nordhaus, Jason

    2015-01-01

    In anticipation of the July 2015 flyby of the Pluto system by NASA's New Horizons mission, we propose naming conventions and example names for surface features on Pluto and its satellites (Charon, Nix, Hydra, Kerberos, Styx) and names for newly discovered satellites.

  15. Review and Development on the Studies of Chinese Meteorological Satellite and Satellite Meteorology

    Institute of Scientific and Technical Information of China (English)

    FANG Zongyi; XU Jianmin; ZHAO Fengsheng

    2006-01-01

    Meteorological satellite and satellite meteorology are the fastest developing new branches in the atmospheric sciences. Today the meteorological satellite has become a key element in the global atmospheric sounding system while the satellite meteorology is covering the main components of earth's system science.This article describes the major achievements that China has made in these fields in the past 30 years.The following contents are involved: (1) History and present status of China's meteorological satellites. It covers the development, launch, operation, technical parameters of China's polar and geostationary meteorological satellites. (2) Major achievements on remote sensing principle and method. It describes the retrieval of atmospheric temperature and humidity profiles, cloud character retrieval, aerosol character retrieval, precipitation retrieval as well as the generation of cloud wind. (3) Achievement on the studies of meteorological satellite data application. This part covers the applications of meteorological satellite data to weather analysis and forecast, numerical forecast, climate monitoring, and prediction of short-term climate change. Besides, the new results on data assimilation, climate monitoring, and forecast are also included.

  16. Small Earth Observing Satellites Flying with Large Satellites in the A-Train

    Science.gov (United States)

    Kelly, Angelita C.; Loverro, Adam; Case, Warren F.; Queruel, Nadege; Marechal, Chistophe; Barroso, Therese

    2009-01-01

    This paper/poster presents a real-life example of the benefits of flying small satellites with other satellites, large or small, and vice versa. Typically, most small satellites fly payloads consisting of one or two instruments and fly in orbits that are independent from that of other satellites. The science data from these satellites are either used in isolation or correlated with instrument data from other satellites. Data correlation with other satellites is greatly improved when the measurements of the same point or air mass are taken at approximately the same time. Scientists worldwide are beginning to take advantage of the opportunities for improved data correlation, or coincidental science, offered by the international Earth Observing Constellation known as the A-Train (sometimes referred to as the Afternoon Constellation). Most of the A-Train satellites are small - the A-Train is anchored by two large NASA satellites (EOS-Aqua and EOS-Aura), but consists also of 5 small satellites (CloudSat, CALIPSO, PARASOL, OCO and Glory these last two will join in 2009). By flying in a constellation, each mission benefits from coincidental observations from instruments on the other satellites in the constellation. Essentially, from a data point of view, the A-Train can be envisioned as a single, virtual science platform with multiple instruments. Satellites in the A-Train fly at 705 km in sun-synchronous orbits. Their mean local times at the equator are within seconds to a few minutes of each other. This paper describes the challenges of operating an international constellation of independent satellites from the U.S. and Europe to maximize the coincidental science opportunities while at the same time minimizing the level of operational interactions required between team members. The A-Train mission teams have been able to demonstrate that flying as members of an international constellation does not take away the flexibility to accommodate new requirements. Specific

  17. Autonomous satellite constellation orbit determination using the star sensor and inter-satellite links data

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A method of autonomous orbit determination for a satellite constellation using a star sensor combined with inter satellite links(ISLs) is studied.Two types of simulated observation data,Three-Satellite Constellation ISLs and background stellar observations by a CCD star sensor,are first produced.Based on these data,an observation equation is built for the constellation joint autonomous orbit determination,in which the simulations are run.The accuracy of this method with different orbital determination models are analyzed and compared with regard to the effect of potential measurement errors.The results show that autonomous satellite constellation orbit determination using star sensor measurement and ISLs data is feasible.Finally,this paper arrives at several conclusions which contribute to extending this method to a more general satellite constellation.

  18. Satellite Contributions to Global Change Studies

    Science.gov (United States)

    Parkinson, Claire L.

    2009-01-01

    By providing a global view with a level playing field (no region missed because of unfavorable surface conditions or political boundaries), satellites have made major contributions to improved monitoring and understanding of our constantly changing planet. The global view has allowed surprising realizations like the relative sparsity of lightning strikes over oceans and the large-scale undulations on the massive Antarctic ice sheet. It has allowed the tracking of all sorts of phenomena, including aerosols, both natural and anthropogenic, as they move with the atmospheric circulation and impact weather and human health. But probably nothing that the global view allows is more important in the long term than its provision. of unbiased data sets to address the issue of global change, considered by many to be among the most important issues facing humankind today. With satellites we can monitor atmospheric temperatures at all latitudes and longitudes, and obtain a global average that lessens the likelihood of becoming endlessly mired in the confusions brought about by the certainty of regional differences. With satellites we can monitor greenhouse gases such as CO2 not just above individual research stations but around the globe. With satellites we can monitor the polar sea ice covers, as we have done since the late 1970s, determining and quantifying the significant reduction in Arctic sea ice and the slight growth in Antarctic sea ice over that period, With satellites we can map the full extent and changes in the Antarctic stratospheric ozone depletions that were first identified from using a single ground station; and through satellite data we have witnessed from afar land surface changes brought about by humans both intentionally, as with wide-scale deforestation, and unintentionally, as with the decay of the Aral Sea. The satellite data are far from sufficient for all that we need in order to understand the global system and forecast its changes, as we also need

  19. Potential markets for advanced satellite communications

    Science.gov (United States)

    Adamson, Steven; Roberts, David; Schubert, Leroy; Smith, Brian; Sogegian, Robert; Walters, Daniel

    1993-09-01

    This report identifies trends in the volume and type of traffic offered to the U.S. domestic communications infrastructure and extrapolates these trends through the year 2011. To describe how telecommunications service providers are adapting to the identified trends, this report assesses the status, plans, and capacity of the domestic communications infrastructure. Cable, satellite, and radio components of the infrastructure are examined separately. The report also assesses the following major applications making use of the infrastructure: (1) Broadband services, including Broadband Integrated Services Digital Network (BISDN), Switched Multimegabit Data Service (SMDS), and frame relay; (2) mobile services, including voice, location, and paging; (3) Very Small Aperture Terminals (VSAT), including mesh VSAT; and (4) Direct Broadcast Satellite (DBS) for audio and video. The report associates satellite implementation of specific applications with market segments appropriate to their features and capabilities. The volume and dollar value of these market segments are estimated. For the satellite applications able to address the needs of significant market segments, the report also examines the potential of each satellite-based application to capture business from alternative technologies.

  20. Quasi-satellite dynamics in formation flight

    CERN Document Server

    Mikkola, Seppo

    2016-01-01

    The quasi-satellite (QS) phenomenon makes two celestial bodies to fly near each other (Mikkola et al. 2006) and that effect can be used also to make artificial satellites move in tandem. We consider formation flight of two or three satellites in low eccentricity near Earth orbits. With the help of weak ion thrusters it is possible to accomplish tandem flight. With ion thrusters it is also possible to mimic many kinds of mutual force laws between the satellites. We found that both a constant repulsive force or an attractive force that decreases with the distance are able to preserve the formation in which the eccentricities cause the actual relative motion and the weak thrusters keep the mean longitude difference small. Initial values are important for the formation flight but very exact adjustment of orbital elements is not important. Simplicity is one of our goals in this study and this result is achieved at least in the way that, when constant force thrusters are used, the satellites only need to detect the...

  1. Teamwork Reasoning and Multi-Satellite Missions

    Science.gov (United States)

    Marsella, Stacy C.; Plaunt, Christian (Technical Monitor)

    2002-01-01

    NASA is rapidly moving towards the use of spatially distributed multiple satellites operating in near Earth orbit and Deep Space. Effective operation of such multi-satellite constellations raises many key research issues. In particular, the satellites will be required to cooperate with each other as a team that must achieve common objectives with a high degree of autonomy from ground based operations. The multi-agent research community has made considerable progress in investigating the challenges of realizing such teamwork. In this report, we discuss some of the teamwork issues that will be faced by multi-satellite operations. The basis of the discussion is a particular proposed mission, the Magnetospheric MultiScale mission to explore Earth's magnetosphere. We describe this mission and then consider how multi-agent technologies might be applied in the design and operation of these missions. We consider the potential benefits of these technologies as well as the research challenges that will be raised in applying them to NASA multi-satellite missions. We conclude with some recommendations for future work.

  2. Testing gravitational physics with satellite laser ranging

    Science.gov (United States)

    Ciufolini, Ignazio; Paolozzi, Antonio; Pavlis, Erricos C.; Ries, John; Koenig, Rolf; Matzner, Richard; Sindoni, Giampiero; Neumeyer, Hans

    2011-08-01

    Laser ranging, both Lunar (LLR) and Satellite Laser Ranging (SLR), is one of the most accurate techniques to test gravitational physics and Einstein's theory of General Relativity. Lunar Laser Ranging has provided very accurate tests of both the strong equivalence principle, at the foundations of General Relativity, and of the weak equivalence principle, at the basis of any metric theory of gravity; it has provided strong limits to the values of the so-called PPN (Parametrized Post-Newtonian) parameters, that are used to test the post-Newtonian limit of General Relativity, strong limits to conceivable deviations to the inverse square law for very weak gravity and accurate measurements of the geodetic precession, an effect predicted by General Relativity. Satellite laser ranging has provided strong limits to deviations to the inverse square gravity law, at a different range with respect to LLR, and in particular has given the first direct test of the gravitomagnetic field by measuring the gravitomagnetic shift of the node of a satellite, a frame-dragging effect also called Lense-Thirring effect. Here, after an introduction to gravitomagnetism and frame-dragging, we describe the latest results in measuring the Lense-Thirring effect using the LAGEOS satellites and the latest gravity field models obtained by the space mission GRACE. Finally, we describe an update of the LARES (LAser RElativity Satellite) mission. LARES is planned for launch in 2011 to further improve the accuracy in the measurement of frame-dragging.

  3. Satellite imagery in safeguards: progress and prospects

    International Nuclear Information System (INIS)

    The use of satellite imagery has become very important for the verification of the safeguards implementation under the Nuclear Non-Proliferation Treaty (NPT). The main applications of satellite imagery are to verify the correctness and completeness of the member states' declarations, and to provide preparatory information for inspections, complimentary access and other technical visits. If the area of interest is not accessible, remote sensing sensors provide one of the few opportunities of gathering data for nuclear monitoring, as for example in Iraq between 1998 and 2002 or currently in North Korea. Satellite data of all available sensor types contains a considerable amount of safeguard-relevant information. Very high-resolution optical satellite imagery provides the most detailed spatial information on nuclear sites and activities up to 0.41 m resolution, together with up to 8 spectral bands from the visible light and near infrared. Thermal infrared (TIR) images can indicate the operational status of nuclear facilities and help to identify undeclared activities. Hyper-spectral imagery allows a quantitative estimation of geophysical, geochemical and biochemical characteristics of the earth's surface and is therefore useful for assessing, for example, surface cover changes due to drilling, mining and milling activities. Synthetic Aperture Radar (SAR) image data up to 1 m spatial resolution provides an all-weather, day and night monitoring capability. However, the absence (or existence) of nuclear activities can never be confirmed completely based on satellite imagery. (A.C.)

  4. The Missing Satellite Problem in 3D

    CERN Document Server

    Nierenberg, A M; Menci, N; Lu, Y; Torrey, Paul; Vogelsberger, M

    2016-01-01

    It is widely believed that the large discrepancy between the observed number of satellite galaxies and the predicted number of dark subhalos can be resolved via a variety of baryonic effects which suppress star formation in low mass halos.Supporting this hypothesis, numerous high resolution simulations with star formation, and associated feedback have been shown to reproduce the satellite luminosity function around Milky Way-mass simulated galaxies at redshift zero. However, a more stringent test of these models is their ability to simultaneously match the satellite luminosity functions of a range of host halo masses and redshifts. In this work we measure the luminosity function of faint (sub-Small Magellanic Cloud luminosity) satellites around hosts with stellar masses 10.5$<\\log_{10}$M$_*$/M$_\\odot<11.5$ to an unprecedented redshift of 1.5. This new measurement of the satellite luminosity function provides powerful new constraining power; we compare these results with predictions from four different s...

  5. Satellite voice broadcase system study. Volume 1: Executive summary

    Science.gov (United States)

    Horstein, M.

    1985-01-01

    The feasibility of providing Voice of America (VOA) broadcasts by satellite relay was investigated. Satellite voice broadcast systems are described for three different frequency bands: HF, FHV, and L-band. Geostationary satellite configurations are considered for both frequency bands. A system of subsynchronous, circular satellites with an orbit period of 8 hours was developed for the HF band. The VHF broadcasts are provided by a system of Molniya satellites. The satellite designs are limited in size and weight to the capability of the STS/Centaur launch vehicle combination. At L-band, only four geostationary satellites are needed to meet the requirements of the complete broadcast schedule. These satellites are comparable in size and weight to current satellites designed for the direct broadcast of video program material.

  6. Satellite anomalies caused by disturbed space weather

    Science.gov (United States)

    Allen, J. H.

    2003-04-01

    Seven types of satellite anomalies are discussed and examples are given from historical reports. Types of anomalies and their causes are: o Single Event Upsets (SEU) caused by penetrating energetic ions; o Deep dielectric ("bulk") charging (DDC) by high-energy electrons; o Surface charging by thermal electrons causing electrostatic discharge (ESD) and Phantom Commands (PC); o Magnetopause crossing events (MPE) that reverse ambient fields at geostationary satellite altitudes; o dB/dT of field-aligned currents causing satellite tumbling at lower altitudes; o Optical effects of high-energy ions on star-trackers and limb sensors; and o Power panel degradation from high-energy ions. Recent and older events are considered, in part because the problems recur even though technology has changed to take them into account and awareness of the conditions causing them seems widespread. Systematic anomaly reporting is requested to increase the significance of records collected for particular events.

  7. Simulating Sinking Satellites with SUPERBOX-10

    CERN Document Server

    Bien, Reinhold; Just, Andreas

    2012-01-01

    SUPERBOX-10 is the successor of SUPERBOX, a particle-mesh code where additional grids and sub-grids are applied to regions of high particle density. Previous limitations have been solved. For instance, the vertical resolution is improved considerably when flattened grids are used. Since the computationally most intensive part is the Fast Fourier Transform, we introduce a parallelised version using the library FFTW, resulting in a speed-up of a few. The new features are tested using a galaxy model consisting of an exponential disc, a bulge and a dark matter halo. We demonstrate that the use of flattened grids efficiently reduces numerical heating. We simulate the merging of disc-bulge-halo galaxies with small spherical satellites. As a result, satellites on orbits with both low eccentricity and inclination heat the disc most efficiently. Moreover, we find that most of the satellite's energy and angular momentum is transfered to the halo.

  8. The investigation of tethered satellite system dynamics

    Science.gov (United States)

    Lorenzini, E. C.

    1986-01-01

    The analysis of the rotational dynamics of the satellite was focused on the rotational amplitude increase of the satellite, with respect to the tether, during retrieval. The dependence of the rotational amplitude upon the tether tension variation to the power 1/4 was thoroughly investigated. The damping of rotational oscillations achievable by reel control was also quantified while an alternative solution that makes use of a lever arm attached with a universal joint to the satellite was proposed. Comparison simulations between the Smithsonian Astrophysical Observatory and the Martin Marietta (MMA) computer code of reteival maneuvers were also carried out. The agreement between the two, completely independent, codes was extremely close, demonstrating the reliability of the models. The slack tether dynamics during reel jams was analytically investigated in order to identify the limits of applicability of the SLACK3 computer code to this particular case. Test runs with SLACK3 were also carried out.

  9. Wind Statistics Offshore based on Satellite Images

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Mouche, Alexis; Badger, Merete;

    2009-01-01

    Ocean wind maps from satellites are routinely processed both at Risø DTU and CLS based on the European Space Agency Envisat ASAR data. At Risø the a priori wind direction is taken from the atmospheric model NOGAPS (Navel Operational Global Atmospheric Prediction System) provided by the U.S. Navy......’s Master Environmental Library. At CLS the a priori wind direction is taken from the ECMWF (European Centre of Medium-range Weather Forecasting). It is also possible to use other sources of wind direction e.g. the satellite-based ASCAT wind directions as demonstrated by CLS. The wind direction has to known...... and Irish Seas. Results comparing satellite scatterometer winds to offshore meteorological observations have shown good results, and more comparisons are planned in this respect during the Norsewind project....

  10. 5th China Satellite Navigation Conference

    CERN Document Server

    Jiao, Wenhai; Wu, Haitao; Lu, Mingquan

    2014-01-01

    China Satellite Navigation Conference (CSNC) 2014 Proceedings presents selected research papers from CSNC2014, held on 21-23 May in Nanjing, China. The theme of CSNC2014 is 'BDS Application: Innovation, Integration and Sharing'. These papers discuss the technologies and applications of the Global Navigation Satellite System (GNSS), and the latest progress made in the China BeiDou System (BDS) especially. They are divided into 9 topics to match the corresponding sessions in CSNC2014, which broadly covered key topics in GNSS. Readers can learn about the BDS and keep abreast of the latest advances in GNSS techniques and applications.  SUN Jiadong is the Chief Designer of the Compass/ BDS, and the Academician of Chinese Academy of Sciences (CAS); JIAO Wenhai is a researcher at China Satellite Navigation Office; WU Haitao is a professor at Navigation Headquarters, CAS; LU Mingquan is a professor at Department of Electronic Engineering of Tsinghua University.

  11. Dwarf satellite galaxies in the modified dynamics

    CERN Document Server

    Milgrom, M

    2000-01-01

    In the modified dynamics (MOND) the inner workings of dwarf satellites can be greatly affected by their mother galaxy-over and beyond its tidal effects. Because of MOND's nonlinearity a system's internal dynamics can be altered by an external field in which it is immersed (even when this field, by itself, is constant in space). As a result, the size and velocity dispersion of the satellite vary as the external field varies along its orbit. A notable outcome of this is a substantial increase in the dwarf's vulnerability to eventual tidal disruption-rather higher than Newtonian dynamics (with a dark-matter halo) would lead us to expect for a satellite with given observed parameters.

  12. ON ASYMMETRIC DISTRIBUTIONS OF SATELLITE GALAXIES

    International Nuclear Information System (INIS)

    We demonstrate that the asymmetric distribution of M31 satellites cannot be produced by tides from the Milky Way as such effects are too weak. However, loosely bound associations and groups of satellites can fall into larger halos and give rise to asymmetries. We compute the survival times for such associations. We prove that the survival time is always shortest in Keplerian potentials, and can be ∼3 times longer in logarithmic potentials. We provide an analytical formula for the dispersal time in terms of the size and velocity dispersion of the infalling structure. We show that, if an association of ∼10 dwarfs fell into the M31 halo, its present aspect would be that of an asymmetric disk of satellites. We also discuss the case of cold substructure in the Andromeda II and Ursa Minor dwarfs

  13. User applications unique to mobile satellites

    Science.gov (United States)

    Castiel, David

    1990-01-01

    As AMSC enters the market with its mobile satellite services, it faces a sophisticated user group that has already experimented with a wide range of communications services, including cellular radio and Ku-band satellite messaging. AMSC's challenge is to define applications unique to the capabilities of its dedicated L band satellite and consistent with the provisions outlined in its FCC license. Through a carefully researched approach to its three main markets (aeronautical, land mobile, and maritime) AMSC is discovering a wellspring of interest in corporate and general aviation, trucking companies, pipeline monitoring and control companies, maritime management firms, telecommunications companies, and government agencies. A general overview is provided of AMSC's FCC license and corporate history, and the specific applications unique to each user group is discussed.

  14. Seasonal streamflow estimation employing satellite snowcover observations

    Science.gov (United States)

    Rango, A.; Salomonson, V. V.; Foster, J. L.

    1975-01-01

    Low resolution meteorological satellite and high resolution earth resources satellite data have been used to map snow covered area over the upper Indus River and the Wind River Mountains of Wyoming, respectively. For the Indus River early spring snow covered area was extracted and related to April through June stream flow from 1967-1971 using a regression equation. Prediction of the April-June 1972 stream flow from the satellite data was within three percent of the actual total. Composited results from two years of data over seven Wind River Mountain watersheds indicated that LANDSAT-1 snow cover observations, separated on the basis of watershed elevation, could also be related to runoff in significant regression equations.

  15. Development of concepts for satellite retrieval devices

    Science.gov (United States)

    Pruett, E. C.; Robertson, K. B., III; Loughead, T. E.

    1979-01-01

    The teleoperator being developed to augment the Space Transportation System (STS) for satellite placement, retrieval, or servicing at altitudes or orbital planes where it would be impractical to use the shuttle is primarily a general purpose propulsion stage that can be fitted with manipulator arms, automated servicers and satellite retrieval devices for particular missions. Design concepts for a general purpose retrieval device for docking with a satellite to which a grappling fixture has been attached, and for a retrieval device for docking with the Solar Maximum Mission (SMM) spacecraft were defined. The mechanical aspects of these two devices are discussed as well as the crew operations involved and problems created by the requirement for remote control. Drawings for the two retrieval device concepts are included.

  16. Satellite Ocean Biology: Past, Present, Future

    Science.gov (United States)

    McClain, Charles R.

    2012-01-01

    Since 1978 when the first satellite ocean color proof-of-concept sensor, the Nimbus-7 Coastal Zone Color Scanner, was launched, much progress has been made in refining the basic measurement concept and expanding the research applications of global satellite time series of biological and optical properties such as chlorophyll-a concentrations. The seminar will review the fundamentals of satellite ocean color measurements (sensor design considerations, on-orbit calibration, atmospheric corrections, and bio-optical algorithms), scientific results from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate resolution Imaging Spectroradiometer (MODIS) missions, and the goals of future NASA missions such as PACE, the Aerosol, Cloud, Ecology (ACE), and Geostationary Coastal and Air Pollution Events (GeoCAPE) missions.

  17. Scheduling Earth Observing Satellites with Evolutionary Algorithms

    Science.gov (United States)

    Globus, Al; Crawford, James; Lohn, Jason; Pryor, Anna

    2003-01-01

    We hypothesize that evolutionary algorithms can effectively schedule coordinated fleets of Earth observing satellites. The constraints are complex and the bottlenecks are not well understood, a condition where evolutionary algorithms are often effective. This is, in part, because evolutionary algorithms require only that one can represent solutions, modify solutions, and evaluate solution fitness. To test the hypothesis we have developed a representative set of problems, produced optimization software (in Java) to solve them, and run experiments comparing techniques. This paper presents initial results of a comparison of several evolutionary and other optimization techniques; namely the genetic algorithm, simulated annealing, squeaky wheel optimization, and stochastic hill climbing. We also compare separate satellite vs. integrated scheduling of a two satellite constellation. While the results are not definitive, tests to date suggest that simulated annealing is the best search technique and integrated scheduling is superior.

  18. Collision Avoidance: Coordination of Predicted Conjunctions between NASA Satellites and Satellites of other Countries

    Science.gov (United States)

    Kelly, A.; Watson, W.

    2014-09-01

    This paper describes one of the challenges facing the flight operations teams of the International Earth Observing constellation satellites at the 705 km orbit, including NASAs satellites. The NASA Earth Science Mission Operations (ESMO) Project has been dealing with predicted conjunctions (close approach) between operational/non-operational space objects and the satellites in the International Earth observing constellations for several years. Constellation satellites include: NASAs Earth Observing System (EOS) Terra, Aqua, and Aura, CloudSat, the joint NASA/CNES CALIPSO mission, Earth Observing 1 (EO-1), the Japan Aerospace and Exploration Agency (JAXA) Global Change Observation Mission-Water 1 (GCOM-W1) mission, the United States Geological Survey (USGS) Landsat 7 and Landsat 8, and until 2013, Argentinas SAC-C mission and the CNES PARASOL mission. The NASA Conjunction Analysis and Risk Assessment (CARA) team provides daily reports to the ESMO Project regarding any high interest close approach events (HIEs) involving the constellation satellites. The daily CARA reports provide risk assessment results that help the operations teams to determine if there is a need to perform a risk mitigation action. If the conjuncting space object is an operational satellite that is capable of maneuvering, the affected satellite team needs to coordinate their action plan with the owner operator of the conjuncting satellite. It is absolutely critical for the two teams to communicate as soon as possible. The goal is to minimize the collision risk; this can happen if both satellite operators do not coordinate their maneuver plans. The constellation teams have established guidelines for coordinating HIEs. This coordination process has worked successfully for several years for satellites that are operated by other organizations in the United States and by NASAs international partners, all with whom NASA has a cooperative agreement. However, the situation is different for HIEs with

  19. Transmitter microdischarges in communications and broadcast Satellites

    Science.gov (United States)

    Briskman, Robert D.; Kaliski, Michael A. R.

    2016-09-01

    Most commercial communications and broadcast satellites operating at microwave radio frequencies use traveling wave tube amplifiers (TWTAs) as high power transmitters. Since TWTAs work at high voltages, it is not uncommon to experience micro-discharges, especially early in life. This observation led to the introduction of an autonomous restart function in the companion high voltage power supply (the electronic power conditioner or EPC) of the TWTA as a safety feature. A microdischarge with enough energy above a threshold would lead to a momentary removal of high voltages, followed by an automatic restart, which is usually sufficient to allow the microdischarge event to clear with minimal loss of RF transmission. In most cases the energy involved in the microdischarge is low enough that the removal of high voltages is not required and the event may go undetected. However, an unusual signature was first noted in early 1997 on a Ku-band satellite transmitter, where the characteristics of the microdischarge event were such that the control anode voltage dropped below nominal and typically recovered over a 20 min period. Such microdischarge events became known as the "20 min Effect" which has since been observed over subsequent years on other Ku-band TWTAs, as well as on Ka-band and S-band satellite TWTA transmitters in numerous satellites. This paper summarizes the in-orbit data on such microdischarges as well as the believed cause. In addition, the paper includes results from three S-band TWTAs which have operated on life test for many years. Due to ease of their monitoring instrumentation as contrast to monitoring microdischarges on orbiting operational satellites via telemetry, new data have been accumulated on this effect. The data substantiate the previous findings that microdischarges do not significantly affect satellite operation or their transmissions nor diminish the TWTAs performance, including long lifetime.

  20. Soviet satellite communications science and technology

    Energy Technology Data Exchange (ETDEWEB)

    Birch, J.N.; Campanella, S.J.; Gordon, G.D.; McElroy, D.R.; Pritchard, W.L.; Stamminger, R.

    1991-08-01

    This is a report by six US scientists and engineers concerning the current state of the art and projections of future Soviet satellite communications technologies. The panel members are experts in satellite stabilization, spacecraft environments, space power generation, launch systems, spacecraft communications sciences and technologies, onboard processing, ground stations, and other technologies that impact communications. The panel assessed the Soviet ability to support high-data-rate space missions at 128 Mbps by evaluating current and projected Soviet satellite communications technologies. A variety of space missions were considered, including Earth-to-Earth communications via satellites in geostationary or highly elliptical orbits, those missions that require space-to-Earth communications via a direct path and those missions that require space-to-Earth communications via a relay satellite. Soviet satellite communications capability, in most cases, is 10 years behind that of the United States and other industrialized nations. However, based upon an analysis of communications links needed to support these missions using current Soviet capabilities, it is well within the current Soviet technology to support certain space missions outlined above at rates of 128 Mbps or higher, although published literature clearly shows that the Soviet Union has not exceeded 60 Mbps in its current space system. These analyses are necessary but not sufficient to determine mission data rates, and other technologies such as onboard processing and storage could limit the mission data rate well below that which could actually be supported via the communications links. Presently, the Soviet Union appears to be content with data rates in the low-Earth-orbit relay via geostationary mode of 12 Mbps. This limit is a direct result of power amplifier limits, spacecraft antenna size, and the utilization of K{sub u}-band frequencies. 91 refs., 16 figs., 15 tabs.

  1. Lens Antenna For Mobile/Satellite Communication

    Science.gov (United States)

    Bodnar, D. G.; Rainer, B. K.

    1988-01-01

    Flat, compact antenna made of stripline elements aimed at fixed elevation angle but steered electronically in azimuth. Design simplified by maintaining fixed elevation and relying on width of beam to cover desired elevation range. Need for phase shifter at each radiating element eliminated by arranging elements in circles and feeding through stripline disks called "R-KR lenses". Used in Mobile/Satellite Service, antenna mounted on top of vehicle on Earth and used to keep transmitted and received antenna beams aimed approximately toward communication satellite.

  2. Hubble Space Telescope Observations of Galilean Satellites

    Science.gov (United States)

    McGrath, M. A.

    One of the premier areas of scientific return from Hubble Space Telescope (HST) observations of solar system objects has been studies of the Galilean satellites of Jupiter. Because these objects are unresolvable in most ground-based observations, HST's spatially resolved imaging and spectroscopy of their surfaces, atmospheres, and electrodynamic interactions with the Jovian magnetosphere have provided unique results. This talk will review highlights of the science results from HST observations of the Galilean satellites, including discovery of auroral emissions at the poles of Ganymede, the recent discovery of molecular sulfur in the Pele plume on Io, and the presence of SO2 in the surface of Callisto.

  3. Vehicle antenna development for mobile satellite applications

    Science.gov (United States)

    Woo, K.

    1988-01-01

    The paper summarizes results of a vehicle antenna program at JPL in support of a developing U.S. mobile satellite services (MSS) designed to provide telephone and data services for the continental United States. Two classes of circularly polarized vehicle antennas have been considered for the MSS: medium-gain, satellite-tracking antennas with 10-12-dBic gain; and low-gain, azimuthally omnidirectional antennas with 3-5-dBic gain. The design and performance of these antennas are described, and the two antennas are shown to have peculiar advantages and disadvantages.

  4. Using satellite data to develop environmental indicators

    International Nuclear Information System (INIS)

    Environmental indicators are increasingly being used in policy and management contexts, yet serious data deficiencies exist for many parameters of interest to environmental decision making. With its global synoptic coverage and the wide range of instruments available, satellite remote sensing has the potential to fill a number of these gaps, yet their potential contribution to indicator development has largely remained untested. In this paper we present results of a pilot effort to develop satellite-derived indicators in three major issue areas: ambient air pollution, coastal eutrophication, and biomass burning. A primary focus is on the vetting of indicators by an advisory group composed of remote sensing scientists and policy makers. (letter)

  5. Observing storm surges from satellite altimetry

    Science.gov (United States)

    Han, Guoqi

    2016-07-01

    Storm surges can cause catastrophic damage to properties and loss of life in coastal communities. Thus it is important to enhance our capabilities of observing and forecasting storm surges for mitigating damage and loss. In this presentation we show examples of observing storm surges around the world using nadir satellite altimetry, during Hurricane Sandy, Igor, and Isaac, as well as other cyclone events. The satellite observations are evaluated against tide-gauge observations and discussed for dynamic mechanisms. We also show the potential of a new wide-swath altimetry mission, the Surface Water and Ocean Topography (SWOT), for observing storm surges.

  6. Satellite radar for monitoring forest resources

    Science.gov (United States)

    Hoffer, Roger M.; Lee, Kyu-Sung

    1990-01-01

    An evaluation is made of the computer analysis results of a study which used Seasat satellite radar data obtained in 1978 and Shuttle Imaging Radar-B data obtained in 1984. The change-detection procedures employed demonstrate that deforestation and reforestation activities can be effectively monitored on the basis of radar data gathered at satellite altitudes. The computer-processing techniques applied to the data encompassed (1) overlay display, (2) ratios, (3) differences, (4) principal-component analysis, and (5) classification; of these, overlay display is noted to quickly and easily yield a qualitative display of the multidate data.

  7. A NOVEL MODULATION FOR MOBILE SATELLITE COMMUNICATIONS

    Institute of Scientific and Technical Information of China (English)

    Xie Zhidong; Bian Dongming; Hu Jing; Sun Qian

    2011-01-01

    It is a challenging problem to design a high performance modulation for mobile satellite communications due to the limited power and bandwidth resource.The paper improves Feher patented Quadrature Phase Shift Keying (FQPSK) by redefining the waveform.The novel FQPSK,with constant envelope,can be used to improve the power efficiency and frequency efficiency of mobile satellite communication.The study shows that the improved FQPSK outperforms conventional FQPSK over AWGN and is immune to the non-linearity of high power amplifier.At last,the impact of flat fading and multi-path fading of channel on the BER performance of improved modulation is analyzed.

  8. Offshore winds mapped from satellite remote sensing

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay

    2014-01-01

    uncertainty on the model results on the offshore wind resource, it is necessary to compare model results with observations. Observations from ground-based wind lidar and satellite remote sensing are the two main technologies that can provide new types of offshore wind data at relatively low cost. The...... advantages of microwave satellite remote sensing are 1) horizontal spatial coverage, 2) long data archives and 3) high spatial detail both in the coastal zone and of far-field wind farm wake. Passive microwave ocean wind speed data are available since 1987 with up to 6 observations per day with near...

  9. Control of the Tevatron Satellite Refrigeration system

    International Nuclear Information System (INIS)

    This chapter describes a computerized control system for 24 satellite refrigerators which cool a six kilometer ring of superconducting magnets. The control system consists of 31 independent microprocessors operating over 400 servo loops, and a central computer system which provides monitoring, alarms, logging and changing of parameters. Topics considered include pressure measurement, flow measurement, temperature measurement, gas analysis, control valves, expansion engine controllers, and control loops. Each refrigerator has 12 active microprocessor based control loops which tune the refrigerator to one of its four operating modes: satellite, liquefier, refrigerator, and stand-by. It is suggested that optimizing the refrigerator control loops and quench recovery scheme will minimize the accelerator down time

  10. Dynamics of Disk Galaxies and Their Satellites

    OpenAIRE

    Héctor Velázquez

    2001-01-01

    We address the heating and survival of galaxy disks by infalling satellites using self-consistent N-body simulations. We consider satellites with a variety of internal structures as well several orbits with different eccentricities and orientations. Also, the role of the central region of the galaxy (through a bulge) is studied. We found that the analytical results of Toth & Ostriker (1992) overestimate the heating and thickening of the disk by a factor of 2-3. In particular, we found disks a...

  11. Contamination control of the Infrared Astronomical Satellite

    Science.gov (United States)

    Andreozzi, L. C.; Irace, W. R.; Maag, C. R.

    1980-01-01

    The Infrared Astronomical Satellite, to be launched in August 1981, will perform an all-sky survey in the 8-120 micron wavelength region. High sensitivity to thermal radiation and the low operating temperature of optics and thermal control surfaces make the IRAS telescope extremely vulnerable to contamination. Four special topics of importance are discussed in this paper: (1) deposition of atmospheric gases; (2) sighting of particles released from the satellite; (3) functions of a deployable aperture cover; and (4) degradation of a radiatively cooled sunshade from spacecraft outgassing. These topics demonstrate how mission strategy, ground cleaning and handling, and hardware design are used to avoid contamination which would degrade telescope performance.

  12. Satellite information for wind energy applications

    DEFF Research Database (Denmark)

    Nielsen, M.; Astrup, Poul; Hasager, Charlotte Bay;

    2004-01-01

    aid to map larger regions within shorter time. Field site observations of obstacles and hedges are still necessary. The raster-based map information from DEMand land cover maps can be converted for use in WASP. For offshore locations it is possible to estimate the wind resources based on ocean surface......An introduction to satellite information relevant for wind energy applications is given. It includes digital elevation model (DEM) data based on satellite observations. The Shuttle Radar Topography Mission (SRTM) is useful for regional scale wind resourcestudies. Comparison results from complex...

  13. Interiors of the icy satellites of Saturn

    Energy Technology Data Exchange (ETDEWEB)

    Cole, G.H.A.

    1983-12-01

    The Voyager flights to Jupiter and Saturn have provided reliable data for the radii, masses and densities of the significant satellites. The smaller satellites of Saturn (Mimas, Enceladus, Tethys, Dione, Rhea and Iapetus) have radii in the range 190-770 km, masses in the range 3 x 10/sup 19/-2x10/sup 21/ kg and mean densities below 1450 kg/m/sup 3/. It is of interest to speculate about the possible composition of such bodies which are likely not to be differentiated.

  14. Diffusive chaos in navigation satellites orbits

    CERN Document Server

    Daquin, J; Tsiganis, K

    2016-01-01

    The navigation satellite constellations in medium-Earth orbit exist in a background of third-body secular resonances stemming from the perturbing gravitational effects of the Moon and the Sun. The resulting chaotic motions, emanating from the overlapping of neighboring resonant harmonics, induce especially strong perturbations on the orbital eccentricity, which can be transported to large values, thereby increasing the collision risk to the constellations and possibly leading to a proliferation of space debris. We show here that this transport is of a diffusive nature and we present representative diffusion maps that are useful in obtaining a global comprehension of the dynamical structure of the navigation satellite orbits.

  15. The Italian contribution to the CSES satellite

    Science.gov (United States)

    Conti, Livio

    2016-04-01

    We present the Italian contribution to the CSES (China Seismo-Electromagnetic Satellite) mission. The CSES satellite aims at investigating electromagnetic field, plasma and particles in the near-Earth environment in order to study in particular seismic precursors, particles fluxes (from Van Allen belts, cosmic rays, solar wind, etc.), anthropogenic electromagnetic pollution and more in general the atmosphere-ionosphere-magnetosphere coupling mechanisms that can affect the climate changes. The launch of CSES - the first of a series of several satellite missions - is scheduled by the end of 2016. The CSES satellite has been financed by the CNSA (China National Space Agency) and developed by CEA (China Earthquake Administration) together with several Chinese research institutes and private companies such as the DFH (that has developed the CAST2000 satellite platform). Italy participates to the CSES satellite mission with the LIMADOU project funded by ASI (Italian Space Agency) in collaboration with the Universities of Roma Tor Vergata, Uninettuno, Trento, Bologna and Perugia, as well as the INFN (Italian National Institute of Nuclear Physics), INGV (Italian National Institute of Geophysics and Volcanology) and INAF-IAPS (Italian National Institute of Astrophysics and Planetology). Many analyses have shown that satellite observations of electromagnetic fields, plasma parameters and particle fluxes in low Earth orbit may be useful in order to study the existence of electromagnetic emissions associated with the occurrence of earthquakes of medium and high magnitude. Although the earthquakes forecasting is not possible today, it is certainly a major challenge - and perhaps even a duty - for science in the near future. The claims that the reported anomalies (of electromagnetic, plasma and particle parameters) are seismic precursors are still intensely debated and analyses for confirming claimed correlations are still lacking. In fact, ionospheric currents, plasma

  16. Solar array experiments on the SPHINX satellite. [Space Plasma High voltage INteraction eXperiment satellite

    Science.gov (United States)

    Stevens, N. J.

    1974-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations: the edge illuminated-multijunction cells, the teflon encased cells, and the violet cells.

  17. The performance of the FODA/IBEA satellite access scheme measured on the Italsat satellite

    OpenAIRE

    Celandroni, Nedo; Ferro, Erina; Potort?, Francesco

    1995-01-01

    This paper briefly describes the FODA/IBEA satellite access scheme and presents part of the experimental results of two studies carried out both on real-time and noo real-time traffic crossing a satellite networkaccessed with the FODA/IBEA access scheme. The jitter affecting the reaJ time data is studied and a solution indicated. while for non real-time data the performance of the capacity assignment algorithm is shown. Tests were carried on the ITALSAT satellite, by using the Multi-applicati...

  18. Space Solar Power Satellite Systems, Modern Small Satellites, and Space Rectenna

    Science.gov (United States)

    Bergsrud, Corey Alexis Marvin

    Space solar power satellite (SSPS) systems is the concept of placing large satellite into geostationary Earth orbit (GEO) to harvest and convert massive amounts of solar energy into microwave energy, and to transmit the microwaves to a rectifying antenna (rectenna) array on Earth. The rectenna array captures and converts the microwave power into usable power that is injected into the terrestrial electric grid for use. This work approached the microwave power beam as an additional source of power (with solar) for lower orbiting satellites. Assuming the concept of retrodirectivity, a GEO-SSPS antenna array system tracks and delivers microwave power to lower orbiting satellites. The lower orbiting satellites are equipped with a stacked photovoltaic (PV)/rectenna array hybrid power generation unit (HPGU) in order to harvest solar and/or microwave energy for on-board use during orbit. The area, and mass of the PV array part of the HPGU was reduced at about 32% beginning-of-life power in order to achieve the spacecraft power requirements. The HPGU proved to offer a mass decrease in the PGU, and an increase in mission life due to longer living component life of the rectenna array. Moreover, greater mission flexibility is achieved through a track and power delivery concept. To validate the potential advantages offered by a HPGU, a mission concept was presented that utilizes modern small satellites as technology demonstrators. During launch, a smaller power receiving "daughter" satellite sits inside a larger power transmitting "mother" satellite. Once separated from the launch vehicle the daughter satellite is ejected away from the mother satellite, and each satellite deploys its respective power transmitting or power receiving hardware's for experimentation. The concept of close proximity mission operations between the satellites is considered. To validate the technology of the space rectenna array part of the HPGU, six milestones were completed in the design. The first

  19. NORSEWInD satellite wind climatology

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Mouche, Alexis;

    provide new offshore wind climatology map for the entire area of interest based on satellite remote sensing. This has been based on Synthetic Aperture Radar (SAR) from Envisat ASAR using 9000 scenes re-processed with ECMWF wind direction and CMOD-IFR. The number of overlapping samples range from 450 in...

  20. A decentralized design philosophy for satellites

    DEFF Research Database (Denmark)

    Nielsen, Jens Frederik Dalsgaard; Larsen, Jesper Abildgaard

    2011-01-01

    For the last decade development and construction of student cubesat satellites has played an important part in the engineering Master Program within Electrical Engineering and Information Technology at Aalborg University, Denmark. As a result three cubesats AAU CUBESAT, AAUSAT-II and AAUSAT3 has...

  1. The surprising inefficiency of dwarf satellite quenching

    CERN Document Server

    Wheeler, Coral; Cooper, Michael C; Boylan-Kolchin, Mike; Bullock, James S

    2014-01-01

    We study dwarf satellite galaxy quenching using observations from the Geha et al. (2012) NSA/SDSS catalog together with LCDM cosmological simulations to facilitate selection and interpretation. We show that fewer than 30% of dwarfs (M* ~ 10^8.5-10^9.5 Msun) identified as satellites within massive host halos (Mhost ~ 10^12.5-10^14 Msun) are quenched, in spite of the expectation from simulations that half of them should have been accreted more than 6 Gyr ago. We conclude that whatever the action triggering environmental quenching of dwarf satellites, the process must be highly inefficient. We investigate a series of simple, one-parameter quenching models in order understand what is required to explain the low quenched fraction and conclude that either the quenching timescale is very long (> 9.5 Gyr, a "slow starvation" scenario) or that the environmental trigger is not well matched to accretion within the virial volume. We discuss these results in light of the fact that most of the low mass dwarf satellites in ...

  2. Monitoring civil infrastructure using satellite radar interferometry

    NARCIS (Netherlands)

    Chang, L.

    2015-01-01

    Satellite radar interferometry (InSAR) is a precise and efficient technique to monitor deformation on Earth with millimeter precision. Most InSAR applications focus on geophysical phenomena, such as earthquakes, volcanoes, or subsidence. Monitoring civil infrastructure with InSAR is relatively new,

  3. Preliminary orbit determination for lunar satellites.

    Science.gov (United States)

    Lancaster, E. R.

    1973-01-01

    Methods for the determination of orbits of artificial lunar satellites from earth-based range rate measurements developed by Koskela (1964) and Bateman et al. (1966) are simplified and extended to include range measurements along with range rate measurements. For illustration, a numerical example is presented.

  4. Image sets for satellite image processing systems

    Science.gov (United States)

    Peterson, Michael R.; Horner, Toby; Temple, Asael

    2011-06-01

    The development of novel image processing algorithms requires a diverse and relevant set of training images to ensure the general applicability of such algorithms for their required tasks. Images must be appropriately chosen for the algorithm's intended applications. Image processing algorithms often employ the discrete wavelet transform (DWT) algorithm to provide efficient compression and near-perfect reconstruction of image data. Defense applications often require the transmission of images and video across noisy or low-bandwidth channels. Unfortunately, the DWT algorithm's performance deteriorates in the presence of noise. Evolutionary algorithms are often able to train image filters that outperform DWT filters in noisy environments. Here, we present and evaluate two image sets suitable for the training of such filters for satellite and unmanned aerial vehicle imagery applications. We demonstrate the use of the first image set as a training platform for evolutionary algorithms that optimize discrete wavelet transform (DWT)-based image transform filters for satellite image compression. We evaluate the suitability of each image as a training image during optimization. Each image is ranked according to its suitability as a training image and its difficulty as a test image. The second image set provides a test-bed for holdout validation of trained image filters. These images are used to independently verify that trained filters will provide strong performance on unseen satellite images. Collectively, these image sets are suitable for the development of image processing algorithms for satellite and reconnaissance imagery applications.

  5. The Proba Satellite Star Tracker Performance

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Denver, Troelz; Betto, Maurizio;

    2005-01-01

    ESA's PROBA satellite features a high degree of autonomy, both technologically and scientifically. It is build around a powerful command, data and AOCS controller and with its less than 100 kg it is a true microsatellite. The scientific mission of PROBA includes a scanning telescope, which calls...

  6. Satellite imagery in a nuclear age

    International Nuclear Information System (INIS)

    Increasingly, high resolution satellite imaging systems are becoming available from multiple and diverse sources with capabilities useful for answering security questions. With increased supply, data availability and data authenticity may be assured. In a commercial market a supplier can ill afford the loss in market share that would result from any falsification of data. Similarly rising competitors willing to sell imagery of national security sites will decrease the tendency to endure self-imposed restrictions on sales of those sites. International organizations operating in the security interests of all nations might also gain preferential access. Costa for imagery will also fall to the point were individuals can afford purchases of satellite images. International organizations will find utility in exploiting imagery for solving international security problems. Housed within international organizations possessing competent staff, procedures, and 'shared destiny' stakes in resolving compliance discrepancies, the use of satellite imagery may provide a degree of stability in a world in which individuals, non-governmental organizations and governments may choose to exploit the available information for political gain. The use of satellite imagery outside these international organizations might not necessarily be aimed at seeking mutually beneficial solutions for international problems

  7. Forest carbon fluxes: A satellite perspective

    Science.gov (United States)

    Morton, Douglas C.

    2016-04-01

    Reducing deforestation and forest degradation offers a quick win for climate mitigation. Using satellite data we are now able to better constrain pantropical estimates of forest loss, reshaping our understanding of the annual to decadal variability in land sources and sinks in the global carbon cycle.

  8. Secondary arc description on satellite solar generators

    OpenAIRE

    Crispel, Pierre; Degond, Pierre; Vignal, Marie-Helene; Roussel, Jean-Francois; Amorim, Emmanuel; Payan, Denis; Cho, Mengu

    2005-01-01

    In this paper, we propose a quasi-neutral model with non-vanishing current describing the expansion of a plasma in an inter-cellular gap on a satellite solar array. Moreover, an electric arc cathode spot model is proposed in order to give suitable boundary conditions for the expansion model.

  9. Europe over the moon with new satellite

    CERN Multimedia

    2002-01-01

    ESA has taken delivery of a 3kg device that it plans to use to complete the first high-resolution map of the moon. The D-CIXS (Demonstration of a Compact Imaging X-Ray Spectrometer) will be aboard the SMART-1 satellite to be launched from French Guyana in South America next February (1/2 page).

  10. Molecular biology of fuselloviruses and their satellites

    DEFF Research Database (Denmark)

    Contursi, Patrizia; Fusco, Salvatore; Cannio, Raffaele;

    2014-01-01

    Fuselloviruses, also known as Sulfolobus Spindle-shaped viruses (SSVs), are "lemon"- or "spindle"-shaped double-stranded DNA viruses. Among them, SSV1, SSV2 and the satellite viruses pSSVx and pSSVi have been investigated at the structural, genetic, transcriptomic, proteomic and biochemical level...

  11. Satellite Attitude Control Using Only Electromagnetic Actuation

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    The primary purpose of this work was to develop control laws for three axis stabilization of a magnetic actuated satellite. This was achieved by a combination of linear and nonlinear system theory. In order to reach this goal new theoretical results were produced in both fields. The focus of the ...

  12. National Responses to International Satellite Television.

    Science.gov (United States)

    Jayakar, Krishna P.

    Star TV, the first international satellite broadcast system in Asia, has had a profound effect on national broadcasting systems, most of which are rigidly controlled, state owned monopoly organizations. The purpose of this paper was to study the response of national governments, media industries, and the general public to this multichannel direct…

  13. Digital, Satellite-Based Aeronautical Communication

    Science.gov (United States)

    Davarian, F.

    1989-01-01

    Satellite system relays communication between aircraft and stations on ground. System offers better coverage with direct communication between air and ground, costs less and makes possible new communication services. Carries both voice and data. Because many data exchanged between aircraft and ground contain safety-related information, probability of bit errors essential.

  14. Objective Crystal Spectrometer on the SRG satellite

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Westergaard, Niels Jørgen Stenfeldt; Rasmussen, I.; Rasmussen, Ib Lundgaard; Schnopper, Herbert W.; Wiebicke, Hans-Joachim; Halm, Ingolf; Geppert, U.R.; Borozdin, K.N.

    1994-01-01

    The flight version of the Objective Crystal Spectrometer (OXS) on the SPECTRUM-X- GAMMA satellite is presented. The spectrometer is a panel that is placed in front of one of the SODART telescopes. It is composed of an array of the three Bragg crystals, LiF(220), Si(111) and RAP(001) for high...

  15. Extrapolating Satellite Winds to Turbine Operating Heights

    DEFF Research Database (Denmark)

    Badger, Merete; Pena Diaz, Alfredo; Hahmann, Andrea N.;

    2016-01-01

    Ocean wind retrievals from satellite sensors are typically performed for the standard level of 10 m. This restricts their full exploitation for wind energy planning, which requires wind information at much higher levels where wind turbines operate. A new method is presented for the vertical...... nearshore areas where most offshore wind farms are built....

  16. Nuclear powered satellite design for shuttle launches

    International Nuclear Information System (INIS)

    Developing technology and the transition period of the late 1970's from expendable launchers to reusable space shuttles and from single satellite designs to standardized and modularized configurations represent a strong motivation and unique opportunity to actively investigate new applications of nuclear power for satellites. Recently, the U.S. Energy Research and Development Administration has initiated studies on various aspects of nuclear powered satellite design and mission problems in order to establish the viability of using such power supplies for future space missions. The work reported here deals primarily with the 100 to 2,000 We power range and consists of many faceted effort. Spacecraft design problems associated with integration of nuclear power are addressed. Launch constraints and interfaces with respect to the space shuttle and those peculiar to nuclear powered vehicles are considered. Design of isotope power generators from an overall mission point of view is considered. A point design exercise is included to illustrate a specific application. Three primary aspects of nuclear powered satellite philosophy are considered. These include space shuttle capabilities, spacecraft design, and power supply design

  17. Monitoring Phenological Trends From Satellite Imagery

    Science.gov (United States)

    Reed, B.; Brown, J.; Whalen, A.

    2004-12-01

    While there is convincing evidence that global climate change is taking place, there is still considerable controversy over the magnitude and consequences of any changes. One of the primary manifestations of climate change is the effect on patterns of vegetation growth; the timing of the growing season, the vigor of vegetation, and vegetation composition. The satellite data record provides an objective view of vegetation activity by measuring surface reflectance values at regular time intervals. Time-series analyses of satellite data can provide information on emerging trends of vegetation dynamics that may be related to global change. The objective of this project is to conduct a trend analysis of vegetation dynamics in the conterminous United States, as measured by satellite data, to assess regions of changing vegetation activity, and to evaluate the regions to determine the driving forces of these changes. To assess vegetation dynamics we analyze phenological metrics (e.g., time of start of season , end of season, duration of season, and seasonally integrated greenness) derived from satellite data and evaluate trends in these metrics by studying the climate record, agricultural statistics, and land cover data bases to assess the driving forces of the trends. The types of trends that we identify include trends toward earlier/later start and end of season, longer/shorter growing seasons, and greater/lesser vegetation production. Early results indicate geographically specific drivers across various ecoregions of the US.

  18. Scientific analysis of satellite ranging data

    Science.gov (United States)

    Smith, David E.

    1994-01-01

    A network of satellite laser ranging (SLR) tracking systems with continuously improving accuracies is challenging the modelling capabilities of analysts worldwide. Various data analysis techniques have yielded many advances in the development of orbit, instrument and Earth models. The direct measurement of the distance to the satellite provided by the laser ranges has given us a simple metric which links the results obtained by diverse approaches. Different groups have used SLR data, often in combination with observations from other space geodetic techniques, to improve models of the static geopotential, the solid Earth, ocean tides, and atmospheric drag models for low Earth satellites. Radiation pressure models and other non-conservative forces for satellite orbits above the atmosphere have been developed to exploit the full accuracy of the latest SLR instruments. SLR is the baseline tracking system for the altimeter missions TOPEX/Poseidon, and ERS-1 and will play an important role in providing the reference frame for locating the geocentric position of the ocean surface, in providing an unchanging range standard for altimeter calibration, and for improving the geoid models to separate gravitational from ocean circulation signals seen in the sea surface. However, even with the many improvements in the models used to support the orbital analysis of laser observations, there remain systematic effects which limit the full exploitation of SLR accuracy today.

  19. Global Warming: Evidence from Satellite Observations

    Science.gov (United States)

    Prabhakara, C.; Iacovazzi, R., Jr.; Yoo, J.-M.

    2001-01-01

    Observations made in Channel 2 (53.74 GHz) of the Microwave Sounding Unit (MSU) radiometer, flown on-board sequential, sun-synchronous, polar orbiting NOAA operational satellites, indicate that the mean temperature of the atmosphere over the globe increased during the period 1980 to 1999. In this study we have minimized systematic errors in the time series introduced by the satellite orbital drift in an objective manner. This is done with the help the onboard warm black body temperature, which is used in the calibration of the MSU radiometer. The corrected MSU Channel 2 observations of the NOAA satellite series reveal that the vertically weighted global mean temperature of the atmosphere, with a peak weight near the mid-troposphere, warmed at the rate of 0.13 K per decade (with an uncertainty of 0.05 K per decade) during 1980 to 1999. The global warming deduced from conventional meteorological data that have been corrected for urbanization effects agrees reasonably with this satellite deuced result.

  20. LTE Adaptation for Mobile Broadband Satellite Networks

    Directory of Open Access Journals (Sweden)

    Bastia Francesco

    2009-01-01

    Full Text Available One of the key factors for the successful deployment of mobile satellite systems in 4G networks is the maximization of the technology commonalities with the terrestrial systems. An effective way of achieving this objective consists in considering the terrestrial radio interface as the baseline for the satellite radio interface. Since the 3GPP Long Term Evolution (LTE standard will be one of the main players in the 4G scenario, along with other emerging technologies, such as mobile WiMAX; this paper analyzes the possible applicability of the 3GPP LTE interface to satellite transmission, presenting several enabling techniques for this adaptation. In particular, we propose the introduction of an inter-TTI interleaving technique that exploits the existing H-ARQ facilities provided by the LTE physical layer, the use of PAPR reduction techniques to increase the resilience of the OFDM waveform to non linear distortion, and the design of the sequences for Random Access, taking into account the requirements deriving from the large round trip times. The outcomes of this analysis show that, with the required proposed enablers, it is possible to reuse the existing terrestrial air interface to transmit over the satellite link.

  1. Solar power satellite system sizing tradeoffs

    Energy Technology Data Exchange (ETDEWEB)

    Arndt, G.D.; Monford, L.G.

    1981-02-01

    Technical and economic tradeoffs of smaller solar power satellite systems configured with larger antennas, reduced output power, and smaller rectennas, are considered. The differential costs in electricity for seven antenna/rectenna configurations operating at 2.45 GHz and five satellite systems operating at 5.8 GHz are calculated. Two 2.45 GHz configurations dependent upon the ionospheric power density limit are chosen as examples. If the ionospheric limit could be increased to 54 mW sq/cm from the present 23 mW sq/cm level, a 1.53 km antenna satellite operating at 2.45 GHz would provide 5.05 GW of output power from a 6.8 km diameter rectenna. This system gives a 54 percent reduction in rectenna area relative to the reference solar power satellite system at a modest 17 percent increase in electricity costs. At 5.8 GHz, an 0.75 km antenna providing 2.72 GW of power from a 5.8 km diameter rectenna is selected for analysis. This configuration would have a 67 percent reduction in rectenna area at a 36 percent increase in electricity costs. Ionospheric, atmospheric, and thermal limitations are discussed. Antenna patterns for three configurations to show the relative main beam and sidelobe characteristics are included.

  2. Global canopy interception from satellite observations

    Science.gov (United States)

    A new methodology for retrieving rainfall interception rates from multi satellite observations is presented. The approach makes use of the daily productof the Global Precipitation Climatology Project (GPCP) as driving data and applies Gash’s analytical model to derive interception rates at global sc...

  3. Inter-satellite links for cubesats

    NARCIS (Netherlands)

    Budianu, A.; Castro, T.J.W.; Meijerink, A.; Bentum, M.J.

    2013-01-01

    Realizing inter-satellite links is a must for ensuring the success of cubesat swarm missions. Nevertheless, it has hardly been considered until now. The communication systems for cubesats have to deal with a few peculiar demands regarding consumed power, geometry and throughput. Depending on the typ

  4. User Validation of VIIRS Satellite Imagery

    Directory of Open Access Journals (Sweden)

    Don Hillger

    2015-12-01

    Full Text Available Visible/Infrared Imaging Radiometer Suite (VIIRS Imagery from the Suomi National Polar-orbiting Partnership (S-NPP satellite is the finest spatial resolution (375 m multi-spectral imagery of any operational meteorological satellite to date. The Imagery environmental data record (EDR has been designated as a Key Performance Parameter (KPP for VIIRS, meaning that its performance is vital to the success of a series of Joint Polar Satellite System (JPSS satellites that will carry this instrument. Because VIIRS covers the high-latitude and Polar Regions especially well via overlapping swaths from adjacent orbits, the Alaska theatre in particular benefits from VIIRS more than lower-latitude regions. While there are no requirements that specifically address the quality of the EDR Imagery aside from the VIIRS SDR performance requirements, the value of VIIRS Imagery to operational users is an important consideration in the Cal/Val process. As such, engaging a wide diversity of users constitutes a vital part of the Imagery validation strategy. The best possible image quality is of utmost importance. This paper summarizes the Imagery Cal/Val Team’s quality assessment in this context. Since users are a vital component to the validation of VIIRS Imagery, specific examples of VIIRS imagery applied to operational needs are presented as an integral part of the post-checkout Imagery validation.

  5. Satellite quantum communication towards GEO distances

    Science.gov (United States)

    Vallone, Giuseppe; Dequal, Daniele; Tomasin, M.; Schiavon, M.; Vedovato, F.; Bacco, Davide; Gaiarin, Simone; Bianco, Giuseppe; Luceri, Vincenza; Villoresi, Paolo

    2016-04-01

    We report on several experiments of single photon transmission from space to ground realized at the Matera Laser Ranging Observatory (MLRO) of the Italian Space Agency in Matera (Italy). We simulated a source of coherent pulses attenuated to the single photon level by exploiting laser ranging satellites equipped with corner-cube retroreflectors (CCRs). By such technique we report QC with qubits encoded in polarization from low-Earth-orbit (LEO) at distance up to 2500km from the ground station, achieving a low quantum bit error ratio (QBER) for different satellites. The same technique is exploited to demonstrate single photon exchange with a medium-Earth-orbit (MEO) satellite, Lageos-2 at more than 7000 km of distance from the MLRO station. In both experiments the temporal jitter of the received counts is of the order of 1.2ns FWHM due to the intrinsic jitter of the single photon detectors. In order to improve the discrimination of signal from the background and reaching distances corresponding to GEO satellites, we improved the detection scheme by using fast single photon detectors with 40 ps FWHM jitter. We report improved single photon detection jitter from Beacon-C and Ajisai, obtaining 340 ps FWHM in the best case.

  6. The chemical composition of the Galileian satellites

    CERN Document Server

    Celebonovic, V

    1998-01-01

    Using the semiclassical theory of dense matter proposed by P.Savic and R.Kasanin,the mean molecular masses of the Galilean satellites of Jupiter are determined.The calculated values are fitted by plausible combinations of chemical elements,and the results are in good agreement with the observations by "Galileo".Possible cosmogonical explanations are briefly discussed.

  7. Electronic correlations and satellites in superconducting oxides

    International Nuclear Information System (INIS)

    The satellite observed at binding energy of 12--13 eV below the Fermi level in the high-T/sub c/ oxide superconductors La/sub 2-//sub x/Sr/sub x/CuO4 and YBa2Cu3O/sub 7-//sub δ/ is viewed as originating from a state with two holes bound at the same Cu site. As in the case of Ni metal, the satellite is caused by an intra-d-shell shakeup process into a Cu 3d8 final state and its intensity is enhanced at resonance because of a super-Koster-Kronig transition. Based on the t-matrix approach for the hole self-energy, we study the effect of electronic correlations on the one-electron band structure. We examine the position of the satellite and find a large Coulomb interaction energy of ∼5 eV at the Cu site when the experimental satellite position is duplicated by the theory. Since this energy is comparable with the 3d bandwidth, the two-hole bound state is a high-energy excitation. This indicates that in the ground state a creation of two holes at the Cu site is unlikely and thus holes are formed at the O sites when Sr is substituted for La in La2CuO4 and when the oxidation is increased in YBa2Cu3O/sub 7-//sub δ/

  8. Isolated Galaxies and Isolated Satellite Systems

    CERN Document Server

    Ann, H B; Choi, Yun-Young

    2009-01-01

    We search for isolated galaxies using a volume-limited sample of galaxies with 0.02r_{vir,nei} and \\rho <\\bar{\\rho} well segregates the CIG galaxies. We confirm the morphology conformity between the host and their satellites, which suggests importance of hydrodynamic interaction among galaxies within their virial radii in galaxy evolution.

  9. Satellite-Friendly Protocols and Standards

    Science.gov (United States)

    Koudelka, O.; Schmidt, M.; Ebert, J.; Schlemmer, H.; Kastner, S.; Riedler, W.

    2002-01-01

    We are currently observing a development unprecedented with other services, the enormous growth of the Internet. Video, voice and data applications can be supported via this network in high quality. Multi-media applications require high bandwidth which may not be available in many areas. When making proper use of the broadcast feature of a communications satellite, the performance of the satellite-based system can compare favourably to terrestrial solutions. Internet applications are in many cases highly asymmetric, making them very well suited to applications using small and inexpensive terminals. Data from one source may be used simultaneously by a large number of users. The Internet protocol suite has become the de-facto standard. But this protocol family in its original form has not been designed to support guaranteed quality of service, a prerequisite for real-time, high quality traffic. The Internet Protocol has to be adapted for the satellite environment, because long roundtrip delays and the error behaviour of the channel could make it inefficient over a GEO satellite. Another requirement is to utilise the satellite bandwidth as efficiently as possible. This can be achieved by adapting the access system to the nature of IP frames, which are variable in length. In the framework of ESA's ARTES project a novel satellite multimedia system was developed which utilises Multi-Frequency TDMA in a meshed network topology. The system supports Quality of Service (QoS) by reserving capacity with different QoS requirements. The system is centrally controlled by a master station with the implementation of a demand assignment (DAMA) system. A lean internal signalling system has been adopted. Network management is based on the SNMP protocol and industry-standard network management platforms, making interfaces to standard accounting and billing systems easy. Modern communication systems will have to be compliant to different standards in a very flexible manner. The

  10. Extreme Thunderstorms as Seen by Satellite

    Science.gov (United States)

    Cecil, Daniel J.

    2014-01-01

    Extreme events by their nature fall outside the bounds of routine experience. With imperfect or ambiguous measuring systems, it is appropriate to question whether an unusual measurement represents an extreme event or is the result of instrument errors or other sources of noise. About three weeks after the Tropical Rainfall Measuring Mission (TRMM) satellite began collecting data in Dec 1997, a thunderstorm was observed over northern Argentina with 85 GHz brightness temperatures below 50 K and 37 GHz brightness temperatures below 70 K (Zipser et al. 2006). These values are well below what had previously been observed from satellite sensors with lower resolution. The 37 GHz brightness temperatures are also well below those measured by TRMM for any other storm in the subsequent 16 years. Without corroborating evidence, it would be natural to suspect a problem with the instrument, or perhaps an irregularity with the platform during the first weeks of the satellite mission. But the TRMM satellite also carries a radar and a lightning sensor, both confirming the presence of an intense thunderstorm. The radar recorded 40+ dBZ (decibels relative to Z) reflectivity up to about 19 km altitude. More than 200 lightning flashes per minute were recorded. That same storm's 19 GHz brightness temperatures below 150 K would normally be interpreted as the result of a low-emissivity water surface (e.g., a lake, or flood waters) if not for the simultaneous measurements of such intense convection. This paper will examine records from TRMM and related satellite sensors including SSMI and AMSR-E to find the strongest signatures resulting from thunderstorms, and distinguishing those from sources of noise. The lowest brightness temperatures resulting from thunderstorms as seen by TRMM have been in Argentina in November and December. For SSMI sensors carried on five DMSP satellites examined so far, the lowest thunderstorm-related brightness temperatures have been from Argentina in November

  11. Using satellite precipitation data for hydrological modeling

    Science.gov (United States)

    Commandeur, Tom

    2013-04-01

    The growing demand for precipitation data covering larger areas of the globe as lead to the need of innovative approaches to the operationalization of data streams. One possible classical solution is combining and calibrating various ground radar stations, however the availability and cost of these data streams work against its use for global coverage . The alternative is to use Earth Observation data from satellites. There is a wide range of weather data available from polar orbital satellites with sensors for measurements. The biggest advantage is that the spatial coverage is wide, however the temporal resolution for the covered area is more limited. To take advantage of the better of two worlds, geostationary satellites can be used to give the temporal resolution for the same covered area at a regular interval. EUMETSAT's Multi-Sensor Precipitation Estimate (MPE) is based on a classical blending algorithm. This algorithm combines SSM/I instruments on DMSP satellites with the 10.8 micron IR window channel on Meteosat satellites. The result is precipitation estimates with a spatial coverage on most of Europe and Africa and a temporal resolution of 15 minutes. To be able to receive the latest MPE data from EUMETSAT in near real-time a reception station for EUMETCast needs to be set up. With this reception station all data received from Meteosat satellites can be acquired as well as third-party products. The data is post-processed by Meteorological Products Extraction Facility of EUMETSAT, mostly for correction of image distortion and quality assurance. Due to this the data is received with a delay of about 15 minutes. MPE data is stored, by default, in Geostationary Satellite View projection and needs to be transformed into a usable projection system. Projections are translated into WGS84 after which they can be interpolated onto a regular spaced latitude/longitude grid. This paper handles the description of the process of transformation and interpolation

  12. Tectonics of the Outer Planet Satellites

    Science.gov (United States)

    McKinnon, W. B.; Collins, G. C.; Moore, J. M.; Nimmo, F.; Pappalardo, R. T.; Prockter, L. M.; Schenk, P. M.

    2010-01-01

    Tectonic features on the satellites of the outer planets range from the familiar, such as clearly recognizable graben on many satellites, to the bizarre, such as the ubiquitous double ridges on Europa, the twisting sets of ridges on Triton, or the isolated giant mountains rising from Io's surface. All of the large and middle-sized outer planet satellites except Io are dominated by water ice near their surfaces. Though ice is a brittle material at the cold temperatures found in the outer solar system, the amount of energy it takes to bring it close to its melting point is lower than for a rocky body. Therefore, some unique features of icy satellite tectonics may be influenced by a near-surface ductile layer beneath the brittle surface material, and several of the icy satellites may possess subsurface oceans. Sources of stress to drive tectonism are commonly dominated by the tides that deform these satellites as they orbit their primary giant planets. On several satellites, the observed tectonic features may be the result of changes in their tidal figures, or motions of their solid surfaces with respect to their tidal figures. Other driving mechanisms for tectonics include volume changes due to ice or water phase changes in the interior, thermoelastic stress, deformation of the surface above rising diapirs of warm ice, and motion of subsurface material toward large impact basins as they fill in and relax. Most satellites exhibit evidence for extensional deformation, and some exhibit strike-slip faulting, whereas contractional tectonism appears to be rare. Io s surface is unique, exhibiting huge isolated mountains that may be blocks of crust tilting and foundering into the rapidly emptying interior as the surface is constantly buried by deposits from hyperactive volcanoes. Of the satellites, diminutive Enceladus is spectacularly active; its south polar terrain is a site of young tectonism, copious heat flow, and tall plumes venting into space. Europa's surface is

  13. DS-CDMA satellite diversity reception for personal satellite communication: Downlink performance analysis

    Science.gov (United States)

    DeGaudenzi, Riccardo; Giannetti, Filippo

    1995-01-01

    The downlink of a satellite-mobile personal communication system employing power-controlled Direct Sequence Code Division Multiple Access (DS-CDMA) and exploiting satellite-diversity is analyzed and its performance compared with a more traditional communication system utilizing single satellite reception. The analytical model developed has been thoroughly validated by means of extensive Monte Carlo computer simulations. It is shown how the capacity gain provided by diversity reception shrinks considerably in the presence of increasing traffic or in the case of light shadowing conditions. Moreover, the quantitative results tend to indicate that to combat system capacity reduction due to intra-system interference, no more than two satellites shall be active over the same region. To achieve higher system capacity, differently from terrestrial cellular systems, Multi-User Detection (MUD) techniques are likely to be required in the mobile user terminal, thus considerably increasing its complexity.

  14. A new satellite to satellite tracking algorithm from Doppler-shifted frequency measurements

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new satellite to satellite tracking (SST) algorithm from Doppler-shifted frequency measurements is proposed. The estimation principle is demonstrated and the mathematic model of SST is established. The state estimation methods for a user (the cooperative case) and target satellites (the non-cooperative case) are presented based on particle swarm optimization (PSO). The Cramer-Rao lower bounds (CRLB) are deduced as well. Performance of the new algorithm is validated through computer simulations, which proved that the proposed method is effective in terms of the estimation quality compared with CRLB and superior in accuracy to the Bearings-Only (BO) method in almost all simulation cases except for the case that an enough long tracking arc-length is obtained for a user satellite.

  15. The power of inexpensive satellite constellations

    Science.gov (United States)

    Dyrud, Lars P.; La Tour, Rose; Swartz, William H.; Nag, Sreeja; Lorentz, Steven R.; Hilker, Thomas; Wiscombe, Warren J.; Papadakis, Stergios J.

    2014-06-01

    Two thematic drivers are motivating the science community towards constellations of small satellites, the revelation that many next generation system science questions are uniquely addressed with sufficient numbers of simultaneous space based measurements, and the realization that space is historically expensive, and in an environment of constrained costs, we must innovate to ―do more with less‖. We present analysis that answers many of the key questions surrounding constellations of scientific satellites, including research that resulted from the GEOScan community based effort originally intended as hosted payloads on Iridium NEXT. We present analysis that answers the question how many satellites does global system science require? Perhaps serendipitously, the analyses show that many of the key science questions independently converge towards similar results, i.e. that approximately 60+ satellites are needed for transformative, as opposed to incremental capability in system science. The current challenge is how to effectively transition products from design to mass production for space based instruments and vehicles. Ideally, the lesson learned from past designs and builds of various space products should pave the way toward a better manufacturing plan that utilizes just a fraction of the prototype`s cost. Using the commercial products industry implementations of mass customization as an example, we will discuss about the benefits of standardization in design requirements for space instruments and vehicles. For example, the instruments (payloads) are designed to have standardized elements, components, or modules that interchangeably work together within a linkage system. We conclude with a discussion on implementation plans and the new paradigms for community and international cooperation enabled by small satellite constellations.

  16. Tethered Satellite System Contingency Investigation Board

    Science.gov (United States)

    1992-11-01

    The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether

  17. Earth rotation parameters from satellite techniques

    Science.gov (United States)

    Thaller, Daniela; Beutler, Gerhard; Jäggi, Adrian; Meindl, Michael; Dach, Rolf; Sosnica, Krzysztof; Baumann, Christian

    2013-04-01

    It has been demonstrated since several years that satellite techniques are capable of determining Earth Rotation Parameters (ERPs) with a daily or even sub-daily resolution. Especially Global Navigation Satellite Systems (GNSS) with their huge amount of observations can determine time series of polar motion (PM) and length of day (LOD) rather well. But also SLR with its spherical satellites whose orbital motions are easy to model and that allow long orbital arc lengths can deliver valuable contributions to Earth rotation. We analyze GNSS solutions (using GPS and GLONASS) and SLR solutions (using LAGEOS) regarding their potential of estimating polar motion and LOD with daily and subdaily temporal resolution. A steadily improving modeling applied in the analysis of space-geodetic data aims at improved time series of geodetic parameters, e.g., the ERPs. The Earth's gravity field and especially its temporal variations are one point of interest for an improved modeling for satellite techniques. For modeling the short-periodic gravity field variations induced by mass variations in the atmosphere and the oceans the GRACE science team provides the Atmosphere and Ocean Dealiasing (AOD) products. They contain 6-hourly gravity fields of the atmosphere and the oceans. We apply these corrections in the analysis of satellite-geodetic data and show the impact on the estimated ERPs. It is well known that the degree-2 coefficients of the Earth's gravity field are correlated with polar motion and LOD. We show to what extent temporal variations in the degree-2 coefficients are influencing the ERP estimates.

  18. Multi-life cycles utilization of retired satellites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Retired geosynchronous (GEO) communication satellites affect the GEO orbit environment in outer space. According to the new concept of modern design, the authors propose creatively a method of reusing retired GEO communication satellites, through adjusting retired GEO satellites to slightly inclined orbit geosynchronous (SIGSO) satellites. After these retired satellites are applied to the navigation and communication system, integrity of navigation system and positioning accuracy of the system is improved. Meanwhile, some transponders on these retired satellites can be used to establish a new satellite communication service, and initiate the study and utilization of the multi-life cycle for retired satellites. Experimental results show that this project has significant social value and can make remarkable economic benefit.

  19. Preparation to optical communication experiments with geostationary satellite ARTEMIS

    Science.gov (United States)

    Kuzkov, V. P.; Medveskij, M. M.; Yatskiv, D. Ya.; Nedashkovskij, V. N.; Suberlak, V. R.; Glushchenko, Yu. M.; Peretyatko, M. M.; Eremenko, N. A.

    2003-08-01

    We considered necessary conditions and performed expedient calculations for performing laser communication link experiments with geostationary satellite ARTEMIS (ESA). The scheme was proposed of performing these experiments by using two telescopes. The results of observation of the satellite are presented.

  20. Optimal Release Control of Companion Satellite System Using Electromagnetic Forces

    Institute of Scientific and Technical Information of China (English)

    Zengwen Xu,Peng Shi; Yushan Zhao∗

    2015-01-01

    Electromagnetic forces generated by the inter⁃action of component satellites can be used to release companion satellites. Optimal release trajectories for companion satellite system using inter⁃electromagnetic forces were investigated. Firstly, nonlinear relative motion dynamic equations of a two⁃craft electromagnetic companion satellite system were derived in spatial polar coordinates. Then principles of electromagnetic satellite formation flying were introduced. Secondly, the characteristics of the electromagnetic companion satellites release were analyzed and optimal release trajectories of companion satellites using electromagnetic forces were obtained using Gauss pseudospectral method. Three performance criteria were chosen as minimum time, minimum acceleration of the separation distance and minimum control acceleration. Finally, three release examples including expansion along separation distance, rotation in orbital plane and stable formation reconfiguration were given to demonstrate the feasibility of this method. Results indicated that the release trajectories can converge to optimal solutions effectively and the concept of release companion satellites using electromagnetic forces is practicable.

  1. Defense Meteorological Satellite Program (DMSP) - Space Weather Sensors

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Defense Meteorological Satellite Program (DMSP) maintains a constellation of sun-synchronous, near-polar orbiting satellites. The orbital period is 101 minutes...

  2. Multi-life cycles utilization of retired satellites

    Institute of Scientific and Technical Information of China (English)

    SHI HuLi; AI GuoXiang; HAN YanBen; MA LiHua; CHEN JiBin; GENG JianPing

    2009-01-01

    Retired geosynchronous (GEO) communication satellites affect the GEO orbit environment in outer apace.According to the new concept of modern design,the authors propose creatively a method of reusing retired GEO communication satellites,through adjusting retired GEO satellites to slightly inclined orbit geosynchronous (SIGSO) satellites.After these retired satellites are applied to the navigation and communication system,integrity of navigation system and positioning accuracy of the system is improved.Meanwhile,some transponders on these retired satellites can be used to establish a new satellite communication service,and initiate the study and utilization of the multi-life cycle for retired satellites.Experimental results show that this project has significant social value and can make remarkable economic benefit.

  3. China's FY-3 Polar Orbit Meteorological Satellite And Its Applications

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen; Fang Meng; Sun Anlai

    2009-01-01

    @@ FY-3 is China's second generation of polar orbit meteorological satellite. FY-3A,the first of the FY-3 series,was launched on May 27,2008 from Taiyuan Satellite Launeh Center. After 5 months of in-orbit test,the satellite and its ground application system were put into trial operation on November 18,2008,marking the successful technical upgrading of China's polar-orbit meteorological satellite.

  4. Muscle Satellite Cell Heterogeneity and Self-Renewal

    Directory of Open Access Journals (Sweden)

    Norio eMotohashi

    2014-01-01

    Full Text Available Adult skeletal muscle possesses extraordinary regeneration capacities. After muscle injury or exercise, large numbers of newly formed muscle fibers are generated within a week as a result of expansion and differentiation of a self-renewing pool of muscle stem cells termed muscle satellite cells. Normally, satellite cells are mitotically quiescent and reside beneath the basal lamina of muscle fibers. Upon regeneration, satellite cells are activated, and give rise to daughter myogenic precursor cells. After several rounds of proliferation, these myogenic precursor cells contribute to the formation of new muscle fibers. During cell division, a minor population of myogenic precursor cells returns to quiescent satellite cells as a self-renewal process. Currently, accumulating evidence has revealed the essential roles of satellite cells in muscle regeneration and the regulatory mechanisms, while it still remains to be elucidated how satellite cell self-renewal is molecularly regulated and how satellite cells are important in aging and diseased muscle. The number of satellite cells is decreased due to the changing niche during ageing, resulting in attenuation of muscle regeneration capacity. Additionally, in Duchenne muscular dystrophy (DMD patients, the loss of satellite cell regenerative capacity and decreased satellite cell number due to continuous needs for satellite cells lead to progressive muscle weakness with chronic degeneration. Thus, it is necessary to replenish muscle satellite cells continuously. This review outlines recent findings regarding satellite cell heterogeneity, asymmetric division and molecular mechanisms in satellite cell self-renewal which is crucial for maintenance of satellite cells as a muscle stem cell pool throughout life. In addition, we discuss roles in the stem cell niche for satellite cell maintenance, as well as related cell therapies for approaching treatment of DMD.

  5. Norwegian Student Satellite Program – HiNC Cube

    OpenAIRE

    Oland, Espen; Houge, Torbjørn; Vedal, Frank

    2008-01-01

    The HiNCube project is a student satellite project where the students build a picosatellite that shall take pictures of the Earth. In this paper, an overview of the project is given from an organizational perspective with lessons learned from the process of initiating and performing a satellite project. None of the members in this student managed satellite project had any practical experience with satellite building when the project was initiated. This paper shows how the HiNCube project is i...

  6. Technology for a quasi-GSO satellite communications system

    OpenAIRE

    Katagi, T.; Yonezawa, R.; Chiba, I; Urasaki, S.

    1999-01-01

    In this paper, a satellite communications system using a Quasi Geostationary Satellite Orbit (Quasi-GSO) is proposed. A 24-hour period Quasi-GSO system could give high quality communication to high latitude regions with its satellites observed from earth stations having high elevation angles. In this paper, a system concept and a deployable flat antenna with light weight antenna elements are described proposing it to be a good candidate for mobile communications satellite use.

  7. Development of a Robotics-based Satellites Docking Simulator

    OpenAIRE

    Zebenay, M.

    2014-01-01

    The European Proximity Operation Simulator (EPOS) is a hardware-in-the-loop (HIL) system aiming, among other objectives, at emulating on-orbit docking of spacecraft for verification and validation of the docking phase. This HIL docking simulator set-up essentially consists of docking interfaces, simulating the servicing satellite called chaser satellite, the serviced satellite called target satellite, a sensor of the forces and torques during contact, and two industrial robots that hold the d...

  8. POSSIBILITIES OF USING SATELLITE DATA IN FOREST INVENTORY

    OpenAIRE

    ÖZDEMİR, İbrahim

    2009-01-01

    In the last decade, as a result of developments in the satellite technology, satellite data having different facilities have been presented to user. Many applications and researches relating to using possibilities of satellite data in forest inventory are realized in different countries. With the increase in resolution of satellite data, new researches are still in progress. In this paper, referring some recent applications and researches accomplished in this scope either in world or our coun...

  9. Demonstration of Small Satellite Technologies by the Bird Mission

    OpenAIRE

    K. Brieß; S. Montenegro; Bärwald, W.; Halle, W.; Kayal, H.; E. Lorenz; W. Skrbek; Studemund, H.; Terzibaschian, T.; Walter, I.

    2002-01-01

    The first satellites at the beginning of the space age were small satellites. Primarily because of the fact that the launch capacity was small. Later on the launchers and satellites grew, and today a lot of big missions with a high complexity are in space. These missions serve the science, the military and defense, commercial and operational users as well as public and private interests. Today’s technology allows the supplement of the big missions by small satellite missions. By exploring new...

  10. A virtual reference satellite differential method for relative correction of satellite ephemeris errors

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In order to solve the problems that the novel wide area differential method on the satellite clock and ephemeris relative correction (CERC) in the non-geostationary orbit satellite constellation, a virtual reference satellite (VRS) differential principle using relative correction of satellite ephemeris errors is proposed. It is referred to be as the VRS differential principle, and the elaboration is focused on the construction of pseudo-range errors of VRS. Through qualitative analysis, it can be found that the impact of the satellite’s clock and ephemeris errors on positioning can basically be removed and the users’ positioning errors are near zero. Through simulation analysis of the differential performance, it is verified that the differential method is universal in all kinds of satellite navigation systems with geostationary orbit (GEO) constellation, Medium orbit (MEO) constellation or hybrid orbit constellation, and it has insensitivity to abnormal aspects of a satellite ephemeris and clock. Moreover, the real time positioning accuracy of differential users can be maintained within several decimeters after the pseudo-range measurement noise is effectively weakened or eliminated.

  11. The assimilation of satellite soundings, winds and satellite products in a mesoscale analysis/forecast system

    Science.gov (United States)

    Diak, G. R.; Smith, W. L.

    1985-01-01

    Investigations in FY-85 were centered on three case study days in 1982. Two of these, March 6 and April 24, were Atmospheric Variability Experiment/Verical Atmospheric Sounder (AVE/VAS) days for which high spatial and temporal resolution RAOB and Vertical Atmospheric Sounder (VAS) data sets were available. The third investigation day, April 26, was a day of interesting severe weather. In the last part of FY-84 and early FY-85 we were able to demonstrate most importantly the complimentary nature of satellite soundings and winds in a forecast/analysis system. In our variational analysis scheme, cloud drift and water vapor winds enter into the height field as gradient information. The cloud drift winds especially, have the character of supplying information in cloudy areas where satellite soundings are not possible. In the April 26 experiments, analyses and forecasts using the combination satellite winds and soundings were superior to those using only soundings. Good consistency was shown between independent satellite forecasts from different initialization times run to the same verification time. A significant accomplishment in FY-85 was expanding experiments on April 26 to include quasi-continuous initialization inserting satellite soundings and winds from several different times into an analysis/forecast. Contrary to the first set of experiments on April 26, here forecast initialization fields were not independent, but contained satellite information from two data times.

  12. The escape of natural satellites from Mercury and Venus

    International Nuclear Information System (INIS)

    Kumar's (1977) suggestion that the slow rotations of Mercury and Venus are in part due to natural satellites that subsequently escaped is discussed. A more useful criterion for the escape of such satellites than the previously proposed is derived, and it is shown that this distance is sufficiently small for Mercury and Venus to make the escape of satellites a likely possibility. (Auth.)

  13. 47 CFR 76.127 - Satellite sports blackout.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Satellite sports blackout. 76.127 Section 76... Sports Blackout § 76.127 Satellite sports blackout. (a) Upon the request of the holder of the broadcast rights to a sports event, or its agent, no satellite carrier shall retransmit to subscribers within...

  14. 7 CFR 611.22 - Availability of satellite imagery.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Availability of satellite imagery. 611.22 Section 611... § 611.22 Availability of satellite imagery. Cloud-free maps of the United States based on imagery received from a satellite are prepared and released to the pubic by NRCS. The maps offer the first image...

  15. A generalized transmultiplexer and its application to mobile satellite communications

    Science.gov (United States)

    Ichiyoshi, Osamu

    1990-01-01

    A generalization of digital transmultiplexer technology is presented. The proposed method can realize transmultiplexer (TMUX) and transdemultiplexer (TDUX) filter banks whose element filters have bandwidths greater than the channel spacing frequency. This feature is useful in many communications applications. As an example, a satellite switched (SS) Frequency Division Multiple Access (FDMA) system is proposed for spot beam satellite communications, particularly for mobile satellite communications.

  16. On the perturbations on satellites probing General Relativity

    CERN Document Server

    Sargsyan, S; Mirzoyan, S

    2013-01-01

    Non-gravitational Yarkovsky-Rubincam effect for LAGEOS and LAGEOS 2 satellites used to probe General Relativity has been revealed by means of the Kolmogorov analysis of their perturbations. We present the method and its efficiency at modeling of generated systems with properties expected at the satellite laser ranging measurements and then at satellite residual data analysis.

  17. The introduction to GNOS instrument for FY-3 satellite

    Science.gov (United States)

    Du, Qifei

    2016-07-01

    Global Navigation Satellite System (GNSS) Radio occultation (RO) has become a major atmospheric and ionospheric remote sensing technique and been widely used for numerical weather prediction and global climate monitoring applications. The first GNSS Occultation Sounder (GNOS) developed and manufactured by National Space Science Center (NSSC), Chinese Academy of Science is a RO payload, which has been onboard Fengyun-3 C (FY-3C) satellite and been launched on September 23, 2013. FY-3 series satellites are the Chinese second generation polar-orbiting meteorological satellites with sun-synchronous orbits. During RO events, the GNOS instruments measure the phase delay caused by the Earth's atmospheric and ionospheric refraction between the GNSS satellites and FY-3 satellites, as the relative position between the GNSS satellites and the FY-3 satellites varying, vertical profiles of RO observations (i.e. phase and amplitude) will be obtained, which can be used to derived the atmospheric and ionospheric physical properties such as press, temperature, humidity and ionospheric electron density. In my presentation, we present the characteristics of GNOS instruments for FY-3 series satellites and the result by the instrument in orbit. Firstly, we present the characteristics of GNOS instrument for FY-3C satellite and its precision of atmosphere occultation data. Additionally, we introduce the characteristics of GNOS instrument for FY-3D satellite which will be launched in 2016. Finally, we show the next generation GNOS instrument and its characteristics for the following FY-3 satellites.

  18. Information content in reflected global navigation satellite system signals

    DEFF Research Database (Denmark)

    Høeg, Per; Carlstrom, Anders

    2011-01-01

    The direct signals from satellites in global satellite navigation satellites systems (GNSS) as, GPS, GLONASS and GALILEO, constitute the primary source for positioning, navigation and timing from space. But also the reflected GNSS signals contain an important information content of signal travel...

  19. On the perturbations on satellites probing General Relativity

    International Nuclear Information System (INIS)

    The non-gravitational Yarkovsky–Rubincam effect for the LAGEOS and LAGEOS 2 satellites, which is used to probe General Relativity, has been revealed by means of the Kolmogorov analysis of their perturbations. We present the method and its efficiency at modeling generated systems with properties expected at the satellite laser ranging measurements. We then present a satellite residual data analysis. (paper)

  20. 47 CFR 76.66 - Satellite broadcast signal carriage.

    Science.gov (United States)

    2010-10-01

    ... MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Carriage of Television Broadcast Signals § 76.66 Satellite... television station signals, and that owns or leases a capacity or a service on a satellite in order to... satellite carrier or to a distributor. (4) Television broadcast station. A television broadcast station...