Sample records for geostationary satellite orbit

  1. On orbital allotments for geostationary satellites

    NASA Technical Reports Server (NTRS)

    Gonsalvez, David J. A.; Reilly, Charles H.; Mount-Campbell, Clark A.

    1986-01-01

    The following satellite synthesis problem is addressed: communication satellites are to be allotted positions on the geostationary arc so that interference does not exceed a given acceptable level by enforcing conservative pairwise satellite separation. A desired location is specified for each satellite, and the objective is to minimize the sum of the deviations between the satellites' prescribed and desired locations. Two mixed integer programming models for the satellite synthesis problem are presented. Four solution strategies, branch-and-bound, Benders' decomposition, linear programming with restricted basis entry, and a switching heuristic, are used to find solutions to example synthesis problems. Computational results indicate the switching algorithm yields solutions of good quality in reasonable execution times when compared to the other solution methods. It is demonstrated that the switching algorithm can be applied to synthesis problems with the objective of minimizing the largest deviation between a prescribed location and the corresponding desired location. Furthermore, it is shown that the switching heuristic can use no conservative, location-dependent satellite separations in order to satisfy interference criteria.

  2. The geostationary orbit and satellite communications: concepts older than commonly supposed

    Microsoft Academic Search

    N. Brady

    2002-01-01

    The first proposal for a radio-equipped, man-made satellite in geostationary orbit is customarily attributed to author Arthur Charles Clarke (1917-), however, he makes no claim to having originated the geostationary orbit. Clarke's now classic article, in the October 1945 issue of Wireless World described a system of worldwide broadcasting via three satellites in geostationary orbit. In the article, Clarke listed

  3. Precise Orbit Propagation of Geostationary Satellite Using Cowell's Method

    NASA Astrophysics Data System (ADS)

    Yoon, Jae-Cheol; Choi, Kyu-Hong; Kim, Eun-Kyou

    1997-06-01

    To calculate the position and velocity of the artificial satellite precisely, one has to broil a mathematical model concerning the perturbations by understanding and analysing the space environment correctly and then quantifying. Due to these space environment model, the total acceleration of the artificial satellite can be expressed as the 2nd order differential equation and we build an orbit propagation algorithm by integrating twice this equation by using the Cowell's method which gives the position arid velocity of th artificial satellite at any given time. Perturbations important for the orbits of geostationary spacecraft are the Earth's gravitational potential, the gravitational influence of the sun and moon, and the solar radiation pressure. For precise orbit propagation in Cowell' method, 40 x 40 spherical harmonic coefficients cal be applied and the JPL DE403 ephemeris files were used to generate the range from earth to sun and moo and 8th order Runge-Kutta single step method with variable step-size control is use to integrate the orbit propagation equations.

  4. The use of satellites in non-geostationary orbits for unloading geostationary communication satellite traffic peaks. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    Price, K.; Turner, A.; Nguyen, T.; Doong, W.; Weyandt, C.

    1987-01-01

    The overall objective of this program was to assess the application, economic benefits, and technology and system implications of satellites in non-geostationary (non-GEO) orbits for off-loading peak traffic from GEO communications satellites. The study was organized into four technical tasks which are described in turn. They are: (1) concepts development; (2) system definition; (3) economic comparisons; and (4) technology requirements definition. Each of these tasks is defined in detail and the results of each are given.

  5. Lifetime of objects in geostationary transfer orbit

    Microsoft Academic Search

    G. Janin

    1991-01-01

    Objects in Geostationary Transfer Orbit (GTO) result from the launch of satellites in geostationary orbit. There are close to 200 GTO, most of them third stage rockets used for transferring satellites from low Earth orbit to geostationary orbit. By crossing the low Earth orbit region at high speed more than twice a day, they represent a hazard for low Earth

  6. Mapping daily evapotranspiration at field to continental scales using geostationary and polar orbiting satellite imagery

    NASA Astrophysics Data System (ADS)

    Anderson, M. C.; Kustas, W. P.; Norman, J. M.; Hain, C. R.; Mecikalski, J. R.; Schultz, L.; González-Dugo, M. P.; Cammalleri, C.; D'Urso, G.; Pimstein, A.; Gao, F.

    2011-01-01

    Thermal infrared (TIR) remote sensing of land-surface temperature (LST) provides valuable information about the sub-surface moisture status required for estimating evapotranspiration (ET) and detecting the onset and severity of drought. While empirical indices measuring anomalies in LST and vegetation amount (e.g., as quantified by the Normalized Difference Vegetation Index; NDVI) have demonstrated utility in monitoring ET and drought conditions over large areas, they may provide ambiguous results when other factors (e.g., air temperature, advection) are affecting plant functioning. A more physically based interpretation of LST and NDVI and their relationship to sub-surface moisture conditions can be obtained with a surface energy balance model driven by TIR remote sensing. The Atmosphere-Land Exchange Inverse (ALEXI) model is a multi-sensor TIR approach to ET mapping, coupling a two-source (soil + canopy) land-surface model with an atmospheric boundary layer model in time-differencing mode to routinely and robustly map daily fluxes at continental scales and 5 to 10-km resolution using thermal band imagery and insolation estimates from geostationary satellites. A related algorithm (DisALEXI) spatially disaggregates ALEXI fluxes down to finer spatial scales using moderate resolution TIR imagery from polar orbiting satellites. An overview of this modeling approach is presented, along with strategies for fusing information from multiple satellite platforms and wavebands to map daily ET down to resolutions on the order of 10 m. The ALEXI/DisALEXI model has potential for global applications by integrating data from multiple geostationary meteorological satellite systems, such as the US Geostationary Operational Environmental Satellites, the European Meteosat satellites, the Chinese Fen-yung 2B series, and the Japanese Geostationary Meteorological Satellites. Work is underway to further evaluate multi-scale ALEXI implementations over the US, Europe, Africa and other continents with geostationary satellite coverage.

  7. Mapping daily evapotranspiration at field to global scales using geostationary and polar orbiting satellite imagery

    NASA Astrophysics Data System (ADS)

    Anderson, M. C.; Kustas, W. P.; Norman, J. M.; Hain, C. R.; Mecikalski, J. R.; Schultz, L.; González-Dugo, M. P.; Cammalleri, C.; D'Urso, G.; Pimstein, A.; Gao, F.

    2010-08-01

    Thermal infrared (TIR) remote sensing of land-surface temperature (LST) provides valuable information about the sub-surface moisture status required for estimating evapotranspiration (ET) and detecting the onset and severity of drought. While empirical indices measuring anomalies in LST and vegetation amount (e.g., as quantified by the Normalized Difference Vegetation Index; NDVI) have demonstrated utility in monitoring ET and drought conditions over large areas, they may provide ambiguous results when other factors (soil moisture, advection, air temperature) are affecting plant stress. A more physically based interpretation of LST and NDVI and their relationship to sub-surface moisture conditions can be obtained with a surface energy balance model driven by TIR remote sensing. The Atmosphere-Land Exchange Inverse (ALEXI) model is a multi-sensor TIR approach to ET mapping, coupling a two-source (soil+canopy) land-surface model with an atmospheric boundary layer model in time-differencing mode to routinely and robustly map daily fluxes at continental scales and 5-10 km resolution using thermal band imagery and insolation estimates from geostationary satellites. A related algorithm (DisALEXI), spatially disaggregates ALEXI fluxes down to finer spatial scales using moderate resolution TIR imagery from polar orbiting satellites. An overview of this modeling approach is presented, along with strategies for fusing information from multiple satellite platforms and wavebands to map daily ET down to resolutions of 30 m. The ALEXI/DisALEXI model has potential for global applications by integrating data from multiple geostationary meteorological satellite systems, such as the US Geostationary Operational Environmental Satellites, the European Meteosat satellites, the Chinese Fen-yung 2B series, and the Japanese Geostationary Meteorological Satellites. Work is underway to further evaluate multi-scale ALEXI implementations over the US, Europe and, Africa and other continents with geostationary satellite coverage.

  8. Precipitation nowcasting from geostationary satellite platforms: Neural network methodology exploiting low-Earth-orbit and ground-based data synergy

    NASA Astrophysics Data System (ADS)

    Rivolta, G.; de Rosa, M.; Marzano, F. S.

    2009-04-01

    Many severe meteorological events develop at short time scales. The availability of effective rain-rate nowcasting techniques is valuable for Civil Protection purposes. Neural network based nowcasting techniques, exploiting satellite data, have been proven to be more accurate than conventional techniques. Several rain retrieval techniques have been proposed on the basis of multi-satellite imagery, exploiting passive sensor measurements acquired by Geostationary-Earth-Orbit (GEO) and Low Earth Orbit (LEO) platforms. These approaches tend to overcome some inherent limitations due to the use of satellite thermal infrared (IR) radiances, which are measurements poorly correlated with rainfall. In this respect, microwave (MW) radiometric data available from Low Earth Orbit (LEO) platforms can provide more accurate rain estimates. MW brightness temperatures are fairly sensitive to liquid and ice hydrometeors since rain clouds are not optically opaque at microwave frequencies. GEO satellites can ensure Earth coverage with a high temporal sampling, whereas LEO satellites have the drawback of low temporal sampling. Therefore, LEO-MW and GEO-IR radiometry are clearly complementary for monitoring the Earth's atmosphere and a highly variable phenomenon such as precipitation. The IR radiances from geostationary images can be properly calibrated using microwave-based combined algorithms. Microwave data can be extracted from the microwave imager sensors, but any rain estimation source may be, in general, foreseen. Ground based meteorological radar reflectivity can also be exploited. The objective of this work is to identify guidelines for improving the neural-network approach successfully applied to the rainfall field nowcast from thermal infrared and microwave passive-sensor imagery aboard, respectively, Geostationary-Earth-Orbit (GEO) and Low-Earth-Orbit (LEO) satellites, using infrared (IR) multi-channel data available from Meteosat Second Generation (MSG) and microwave (MW) data from LEO satellites or ground based meteorological Radar. The multi-sensor space-time prediction procedure, being based on the Neural Combined Algorithm for Storm Tracking (NeuCAST), consists of two consecutive steps: first, the infrared radiance fields measured from geostationary satellite radiometer (e.g, MSG) are projected ahead in time (e.g., 30 minutes); secondly, the projected radiance field is used to estimate the rainfall field by means of a MW-IR combined rain retrieval algorithm exploiting GEO-LEO or GEO-Radar observations. The MSG NeuCAST methodology is here illustrated and discussed. Its accuracy is quantified by means of quantitative error indexes, evaluated on selected case studies of rainfall events in Southern Europe between 2003 and 2006.

  9. The development of a Russian communication satellite of small class, operating in the geostationary and high-elliptical orbits

    NASA Astrophysics Data System (ADS)

    Ukhabin, Yu.; Asiushkin, V.; Karutin, N.; Serebrennikov, V.

    In 1994-1995 Lavochkin Association (Russia) together with the other enterprises in accordance with technical requirements of the Russian Space agency, developed a new Russian communication satellite of a small class that will operate in both the geostationary (GSO) and high-elliptical (HEO) orbits. This satellite may be injected into operational orbits using a SOYUZ-2 launch vehicle (LV) and a FREGAT upper stage (US) from Plesetsk and Baykonur space launch sites (SLS). The main reason for creating such a satellite was to decrease the cost of the support and development of the Russian communication geostationary satellites group. Russian satellites Horizont, Express, Ekran and Gals, which operate in GSO, are the basis of the space segment for communications, radio and TV broadcasting. All of these satellites are injected into GSO by the PROTON LV. PROTON is a launch vehicle of a heavy class. The use of a middle class LV instead of a heavy class will allow to reduce considerably the launch cost. The change of a heavy class LV to a LV of middle class determined one economic reason for this project. Besides, the opportunity to launch S/C into GSO from Russian Plesetsk SLS increases the independence of Russia in the domain of space communications, despite the presence of the contract with Kazachstan about the rent of Baykonur SLS. Finally, use of small satellites with a rather small number of transponders is more effective than the use of big satellites. It will allow also to increase a satellite group (by the launch of additional satellites) precisely in accordance to the development of the ground segment.

  10. Asynchronous Processing of a Constellation of Geostationary and Polar-Orbiting Satellites for Fire Detection and Smoke Estimation

    NASA Astrophysics Data System (ADS)

    Hyer, E. J.; Peterson, D. A.; Curtis, C. A.; Schmidt, C. C.; Hoffman, J.; Prins, E. M.

    2014-12-01

    The Fire Locating and Monitoring of Burning Emissions (FLAMBE) system converts satellite observations of thermally anomalous pixels into spatially and temporally continuous estimates of smoke release from open biomass burning. This system currently processes data from a constellation of 5 geostationary and 2 polar-orbiting sensors. Additional sensors, including NPP VIIRS and the imager on the Korea COMS-1 geostationary satellite, will soon be added. This constellation experiences schedule changes and outages of various durations, making the set of available scenes for fire detection highly variable on an hourly and daily basis. Adding to the complexity, the latency of the satellite data is variable between and within sensors. FLAMBE shares with many fire detection systems the goal of detecting as many fires as possible as early as possible, but the FLAMBE system must also produce a consistent estimate of smoke production with minimal artifacts from the changing constellation. To achieve this, NRL has developed a system of asynchronous processing and cross-calibration that permits satellite data to be used as it arrives, while preserving the consistency of the smoke emission estimates. This talk describes the asynchronous data ingest methodology, including latency statistics for the constellation. We also provide an overview and show results from the system we have developed to normalize multi-sensor fire detection for consistency.

  11. Optimal orbit transfers by linear and nonlinear programming for the stochastic optimization of the apogee maneuver of three-axis stabilized geostationary satellites

    Microsoft Academic Search

    A. Leibold

    1980-01-01

    A method for the stochastic optimization of the injection from the transfer orbit and for the deterministic optimization of the positioning after the apogee maneuver for three-axis stabilized geostationary satellites is described. The nonlinear programming problem of the apogee impulse parameter optimization is done by a gradient-free method. During the optimization, error cases in the range of + or -

  12. Geostationary meteorological satellite data collection systems

    Microsoft Academic Search

    DOUGLAS H. MAC CALLUM; MICHAEL J. NESTLEBUSH

    There are three geostationary meteorological satellite data collection systems currently being operated: Geostationary Operational Environmental Satellite (GOES) by the USA; METE0SAT by the European Space Agency (ESA); and Geostationary Meteorological Satellite (GMS) by Japan. Regional or domestic reply frequencies are the same for the METEOSAT and GMS systems while those for the GOES system are different. All three systems have

  13. Monitoring volcanic ash cloud top height through simultaneous retrieval of optical data from polar orbiting and geostationary satellites

    NASA Astrophysics Data System (ADS)

    Zakšek, K.; Hort, M.; Zaletelj, J.; Langmann, B.

    2013-03-01

    Volcanic ash cloud-top height (ACTH) can be monitored on the global level using satellite remote sensing. Here we propose a photogrammetric method based on the parallax between data retrieved from geostationary and polar orbiting satellites to overcome some limitations of the existing methods of ACTH retrieval. SEVIRI HRV band and MODIS band 1 are a good choice because of their high resolution. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. The proposed method was tested for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach 30 km, which implies an ACTH of approximately 12 km at the beginning of the eruption. At the end of April eruption an ACTH of 3-4 km is observed. The accuracy of ACTH was estimated to be 0.6 km.

  14. Monitoring volcanic ash cloud top height through simultaneous retrieval of optical data from polar orbiting and geostationary satellites

    NASA Astrophysics Data System (ADS)

    Zakšek, K.; Hort, M.; Zaletelj, J.; Langmann, B.

    2012-09-01

    Volcanic ash cloud top height (ACTH) can be monitored on the global level using satellite remote sensing. Here we propose a photogrammetric method based on the parallax between data retrieved from geostationary and polar orbiting satellites to overcome some limitations of the existing methods of ACTH retrieval. SEVIRI HRV band and MODIS band 1 are a good choice because of their high resolution. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. The proposed method was tested for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach over 30 km which implies ACTH of more than 12 km in the beginning of the eruption. In the end of April eruption ACTH of 3-4 km is observed. The accuracy of ACTH was estimated to be 0.6 km.

  15. Ionospheric Imaging from Geostationary Orbit

    Microsoft Academic Search

    R. P. McCoy; K. S. Wood; K. F. Dymond; S. E. Thonnard

    2001-01-01

    An ultraviolet imager is under development to image the ionosphere and thermosphere from geostationary orbit. The instrument will consist of two telescopes, one with a filter wheel to measure the atomic oxygen airglow emission at 130.4 nm and 135.6 nm and molecular nitrogen Lyman-Birge-Hopfield bands near 142.5 nm. The second telescope will image the atomic oxygen ion resonance multiplet at

  16. The geostationary orbit and developing countries

    NASA Technical Reports Server (NTRS)

    Medina, E. R.

    1982-01-01

    The geostationary orbit is becoming congested due to use by several countries throughout the world, and the request for use of this orbit is increasing. There are 188 geostationary stations in operation. An equitable distribution of stations on this orbit is requested.

  17. OAA's geostationary and polar-orbiting satellites provide critical data for short-term and

    E-print Network

    , El Niño and La Niña, coral bleaching, ocean acidification, and algae blooms. Real-Time Data for Better Forecasts NOAA operates two types of satellites that provide real-time imagery daily Forest fire detection 4 Global vegetation analysis 4 Search and rescue (continued on back) National

  18. Spacecraft Charging in Geostationary Transfer Orbit

    NASA Astrophysics Data System (ADS)

    Parker, L. N.; Minow, J. I.

    2014-12-01

    The 700 km x 5.8 Re orbit of the two Van Allen Probes spacecraft provide a unique opportunity to investigate surface charging in geostationary transfer orbits. We use records from the Helium Oxygen Proton Electron (HOPE) plasma spectrometer to identify candidate surface charging events based on the "ion line" charging signature in the ion records. We summarize the energetic particle environment and the conditions necessary for charging to occur in this environment. We discuss the altitude, duration, and magnitude of events observed in the Van Allen Probes from the beginning of the mission to present time. In addition, we explore what information the dual satellites provide on the spatial and temporal variations in the charging environments.

  19. Geostationary Lightning Imager for FY4 Meteorological Satellite (Invited)

    Microsoft Academic Search

    F. Huang

    2010-01-01

    The FY-4 satellite scheduled to launch in 2015 is a second-generation Chinese geostationary meteorological satellite. The main payloads for FY-4 satellite include Geostationary Lightning Imager (GLI), Advanced Geostationary Visible and Infrared Imager (AGVII), and Geostationary Interfering Infrared Sounder (GIIRS). Since the GLI is the first lightning detection imager without any heritage on a Chinese meteorological satellite, it is a great

  20. Geostationary Lightning Imager for FY-4 Meteorological Satellite (Invited)

    NASA Astrophysics Data System (ADS)

    Huang, F.

    2010-12-01

    The FY-4 satellite scheduled to launch in 2015 is a second-generation Chinese geostationary meteorological satellite. The main payloads for FY-4 satellite include Geostationary Lightning Imager (GLI), Advanced Geostationary Visible and Infrared Imager (AGVII), and Geostationary Interfering Infrared Sounder (GIIRS). Since the GLI is the first lightning detection imager without any heritage on a Chinese meteorological satellite, it is a great challenge to implement this mission. The GLI covers the most part of China, land and ocean and nearby areas. The continuous and real time lightning imaging products from GLI will be applied to weather forecasting, convection event monitoring, and typhoon tracking. The instrument formulation studies started 4 years ago, and now it is at implementation stage of making prototype models. A working group has begun to develop the L1 and L2 algorithms for lightning imaging data processing. At present, we are focusing on resolving several critical issues for GLI. The first one is how to make sure the Real Time Event Processor (RTEP) works well in orbit, which relates whether or not the lightning information could be picked up correctly. The second is how to make best uses of lightning imaging products from GLI in all kinds of application fields. Since the Geostationary Lightning Mapper (GLM) and Lighting Imager (LI) are lighting imagers on geostationary satellites with similar instrument structure and working principles to GLI, we welcome international collaboration on GLI lightning products: algorithm development, lightning imaging applications, and other relative topics.

  1. Long-term evolution of near-geostationary orbits

    Microsoft Academic Search

    J. C. van der Ha

    1986-01-01

    A model for the long-term evolution of free-drifting near-geostationary satellite orbits is presented. A first-order analytical averaging transformation is applied to the perturbation equations in order to eliminate the short-term (with period of order of one day) variations of the orbital elements. The model includes lunisolar gravitational forces up to the second parallactic term of the moon, zonal and tesseral

  2. Weather Satellite and Orbits

    NSDL National Science Digital Library

    In this interactive, online module, students learn about satellite orbits (geostationary and polar), remote-sensing satellite instruments (radiometers and sounders), satellite images, and the math and physics behind satellite technology. The module is part of an online course for grades 7-12 in satellite meteorology, which includes 10 interactive modules. The site also includes lesson plans developed by teachers and links to related resources. Each module is designed to serve as a stand-alone lesson, however, a sequential approach is recommended. Designed to challenge students through the end of 12th grade, middle school teachers and students may choose to skim or skip a few sections.

  3. Ocean Surface Currents From Geostationary Satellite SST

    E-print Network

    Kurapov, Alexander

    Ocean Surface Currents From Geostationary Satellite SST -We are implementing and evaluating a feature tracking approach to estimate ocean surface currents. - This approach allows us to estimate the surface current vectors from the displacement of small regions of pixels, using sequential images from

  4. Remote sensing of aerosol and radiation from geostationary satellites

    Microsoft Academic Search

    I. Laszlo; P. Ciren; H. Liu; S. Kondragunta; D. Tarpley; M. Goldberg

    2006-01-01

    Real time monitoring of aerosol and surface insolation from the Geostationary Operational Environmental Satellite GOES data have been routinely conducted With the launch of the Geostationary Operational Environmental Satellite GOES-R in 2012 the US National Oceanic and Atmospheric Administration NOAA will begin a new era of geostationary remote sensing The instruments onboard GOES-R will offer capabilities for aerosol remote sensing

  5. Low stratus climatology from geostationary satellite data

    NASA Astrophysics Data System (ADS)

    Cermak, J.; Eastman, R.; Bendix, J.; Warren, S.

    2010-05-01

    Fog and low stratus situations impact traffic safety and air quality; their distribution and frequency impacts radiation transfer in the climate system. This study uses geostationary satellite data (Meteosat Second Generation SEVIRI) to detect low stratus and fog, and to produce climatological maps on this basis. The satellite technique is based on a sequence of spectral and spatial analyses and validated against METAR observations. Averaged maps covering several winter seasons of data are analysed and compared to a cloud climatology based on a 26-year record of ground-based visual cloud observations. Maps are presented for the relative frequency of low stratus situations as well as for the number of hours with fog/low stratus, making use of the very high temporal resolution available from a geostationary platform. The spatial patterns found in both products are found to be in good agreement and plausible.

  6. Geostationary Operational Environmental Satellite (GOES) mission profile

    NASA Technical Reports Server (NTRS)

    Bryant, W. C.; Defazio, R. L.; Sauter, J. A.

    1986-01-01

    The GOES mission profile used to achieve geostationary orbit following separation from the Delta launch vehicle is described. The mission profile was constrained by the solid-propellant apogee kick motor which was undersized relative to the spacecraft weight. The resulting deficiency in delivered delta-V had to be made up by the spacecraft hydrazine propulsion system. The mission profile which best utilizes the on-board hydrazine requires that the transfer orbit apogee height be biased 13,800 km above geosynchronous altitude. This maximizes the effectiveness of the apogee motor in performing the plane change necessary to achieve near-equatorial orbit. The highly eccentric drift orbit which results from the apogee motor firing has an average drift rate of 60 deg/day. Circularizing this orbit requires maneuvers designed to achieve geostationary position within a tightly constrained hydrazine allocation. The sequence takes advantage of the orbit changes resulting from attitude maneuvers and combined inplane/out-of-plane maneuvers to achieve hydrazine savings.

  7. COMBINED USE OF POLAR ORBITING AND GEOSTATIONARY SATELLITES TO IMPROVE TIME INTERPOLATION IN DYNAMIC CROP MODELS FOR FOOD SECURITY ASSESSMENT

    Microsoft Academic Search

    V. Venus; D. Rugege

    Use of satellite data in crop growth monitoring could provide great value for regional food security assessments. By using the difference between remotely sensed crop canopy temperature and the corresponding ambient temperature at the time of the satellite overpass the daily actual rate of transpiration can be inferred. This relationship allows adjustment of the actual rate of assimilation and hence

  8. Propellant gaging for geostationary satellites

    NASA Astrophysics Data System (ADS)

    Orazietti, A. J.; Orton, G. F.; Schreib, R.

    1986-06-01

    Evaluations were performed to select four gaging concepts for ground tests and low-g tests in the NASA KC-135 aircraft. The selected concepts were an ultrasonic point sensor system, a nucleonic gaging system, an ultrasonic torsional wave guide, and an ultrasonic flowmeter. The first three systems provide a direct measurement of propellant quantity remaining, while the fourth system integrates (totalizes) the propellant flow to the engines and infers propellant remaining based on a known initial propellant load. As a result of successful ground and KC-135 tests, two concepts (the ultrasonic point sensor and nucleonic systems) were selected for orbital test in a Shuttle Get-Away-Special experiment. These systems offer high end-of-life accuracy potential, are nonintrusive (external to the tanks and feedlines), and are low in risk because of their good technology base. The Shuttle Get-Away-Special experiment has been assembled and passed flight certification testing in late April 1986.

  9. Relativistic Electrons at Geostationary Orbit: Modeling Results

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Lyatsky, W.

    2008-05-01

    We developed a new prediction model for forecasting relativistic (>2MeV) electrons, which provides a VERY HIGH correlation between predicted and actually measured electron fluxes at geostationary orbit. This model implies the multi-step particle acceleration and is based on numerical integrating two linked continuity equations for primarily accelerated particles and relativistic electrons. The model includes a source and losses, and used solar wind data as only input parameters. We used the coupling function which is a best-fit combination of solar wind/interplanetary magnetic field parameters, responsible for the generation of geomagnetic activity, as a source. The loss function was derived from experimental data. We tested the model for four year period 2004- 2007. The correlation coefficient between predicted and actual values of the electron fluxes for whole four year period as well as for each of these years is stable and incredibly high (about 0.9). The high and stable correlation between the computed and actual electron fluxes shows that the reliable forecasting these electrons at geostationary orbit is possible.

  10. Feasibility study for Japanese Air Quality Mission from Geostationary Satellite: Infrared Imaging Spectrometer

    Microsoft Academic Search

    K. Sagi; Y. Kasai; B. Philippe; K. Suzuki; K. Kita; S. Hayashida; R. Imasu; H. Akimoto

    2009-01-01

    A Geostationary Earth Orbit (GEO) satellite is potentially able to monitor the regional distribution of pollution with good spatial and temporal resolution. The Japan Society of Atmospheric Chemistry (JSAC) and the Japanese Space Exploration Agency (JAXA) initiated a concept study for air quality measurements from a GEO satellite targeting the Asian region [1]. This work presents the results of sensitivity

  11. Characterizing the quiet time magnetic field at geostationary orbit

    NASA Astrophysics Data System (ADS)

    Skone, S. H.; Donovan, E. F.; Rostoker, G.

    1995-12-01

    There is now an increasing body of evidence which suggests that the onset of a substorm expansive phase is triggered in the near-Earth tail region, inside X~-12RE [Samson et al., 1992]. For this reason, it is necessary to characterize the magnetic field in the near-Earth region, particularly the quiet time reference field. We have therefore carried out a detailed study of the magnetic field at geostationary orbit, using data acquired during quiet times from the GOES 5 and GOES 6 satellites which operated simultaneously during 1986. Diurnal and seasonal variations of the total field, and the perturbation magnetic field with the IGRF removed, have been identified and attributed to variations in the position of the neutral sheet with respect to the satellite. We have processed the data to remove seasonal effects by using the semiempirical expression developed by Lopez [1990] to express the displacement of the neutral sheet with respect to the magnetic equatorial plane. We then use our magnetic field model, recently developed by Donovan [1993a], to model the observed quiet time magnetic field at geostationary orbit, and also determine the quiet time current configuration.

  12. Surface solar radiation from geostationary satellites for renewable energy

    Microsoft Academic Search

    Istvan Laszlo; Hongqing Liu; Andrew Heidinger; Mitchell Goldberg

    2010-01-01

    With the launch of the new Geostationary Operational Environmental Satellite, GOES-R, the US National Oceanic and Atmospheric Administration (NOAA) will begin a new era of geostationary remote sensing. One of its flagship instruments, the Advanced Baseline Imager (ABI), will expand frequency and coverage of multispectral remote sensing of atmospheric and surface properties. Products derived from ABI measurements will primarily be

  13. GeoSTAR - A Microwave Sounder for Geostationary Satellites

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn; Wilson, William; Tanner, Alan; Gaier, Todd; Ruf, Chris; Piepmeier, Jeff

    2004-01-01

    GeoSTAR represents a new approach to microwave atmospheric sounding that is now under development. It has capabilities similar to sensors currently operating on low earth orbiting weather satellites but is intended for deployment in geostationary orbit - where it will complement future infrared sounders and enable all-weather temperature and humidity soundings and rain mapping. The required spatial resolution of 50 km or better dictates an aperture of 4 meters or more at a sounding frequency of 50 GHz, which is difficult to achieve with a real aperture system - this is the reason why it has until now not been possible to put a microwave sounder on a geostationary platform. GeoSTAR is instead based on a synthetic aperture imaging approach. Among the advantages of such a system are that there are no moving parts, and the size of the aperture is easily expandable to meet future needs. A ground based prototype of GeoSTAR is currently under development in an effort led by the Jet Propulsion Laboratory.

  14. Assessment of polar orbiting and geostationary satellite active fire retrievals using a suite of ground, airborne and spaceborne reference data sets

    NASA Astrophysics Data System (ADS)

    Schroeder, W.; Csiszar, I. A.; Giglio, L.; Ellicott, E. A.; Justice, C. O.

    2012-12-01

    Major progress involving the validation of satellite active fire products was achieved in recent years thanks to the development of scientifically robust methods and the increased availability of quality reference data sets. For example, the binary (fire-no fire) EOS Terra/MODIS Fire and Thermal Anomalies product (MOD14) was validated using more than 6,000 ASTER and Landsat TM scenes distributed globally. Similar successful story involves the validation of GOES Imager active fire detection product over North and South America. Meanwhile, the validation of fire characterization parameters that usually complement the binary fire detection products has been limited by the lack of reference data sets. Using a scene-independent algorithm applied to NASA's AMS and MASTER airborne instruments, quality fire reference data sets were generated for approximately a dozen different sites each coinciding with a major wildfire in the Western U.S. during 2003-2011, plus a large prescribed fire in California/2011. Complemented by additional ground fire information, the airborne reference data set provided accurate fire retrievals supporting the development of robust techniques to validate MODIS and GOES fire size, temperature, and fire radiative power (FRP - a measure of fire intensity and rate of biomass consumed) data. Here we present these latest results and discuss future implementation of satellite active fire data validation for the new fire product derived from Suomi NPP/VIIRS data, as well as the upcoming GOES-R geostationary satellite based on the projected reference data sensor networks.

  15. Studies of soundings and imagings measurements from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Suomi, V. E.

    1973-01-01

    Soundings and imaging measurements from geostationary satellites are presented. The subjects discussed are: (1) meteorological data processing techniques, (2) sun glitter, (3) cloud growth rate study, satellite stability characteristics, and (4) high resolution optics. The use of perturbation technique to obtain the motion of sensors aboard a satellite is described. The most conditions, and measurement errors. Several performance evaluation parameters are proposed.

  16. Downburst prediction applications of meteorological geostationary satellites

    NASA Astrophysics Data System (ADS)

    Pryor, Kenneth L.

    2014-11-01

    A suite of products has been developed and evaluated to assess hazards presented by convective storm downbursts derived from the current generation of Geostationary Operational Environmental Satellite (GOES) (13-15). The existing suite of GOES downburst prediction products employs the GOES sounder to calculate risk based on conceptual models of favorable environmental profiles for convective downburst generation. A diagnostic nowcasting product, the Microburst Windspeed Potential Index (MWPI), is designed to infer attributes of a favorable downburst environment: 1) the presence of large convective available potential energy (CAPE), and 2) the presence of a surface-based or elevated mixed layer with a steep temperature lapse rate and vertical relative humidity gradient. These conditions foster intense convective downdrafts upon the interaction of sub-saturated air in the elevated or sub-cloud mixed layer with the storm precipitation core. This paper provides an updated assessment of the MWPI algorithm, presents recent case studies demonstrating effective operational use of the MWPI product over the Atlantic coastal region, and presents validation results for the United States Great Plains and Mid-Atlantic coastal region. In addition, an application of the brightness temperature difference (BTD) between GOES imager water vapor (6.5?m) and thermal infrared (11?m) channels that identifies regions where downbursts are likely to develop, due to mid-tropospheric dry air entrainment, will be outlined.

  17. Advanced propulsion for geostationary orbit insertion and north-south station keeping

    Microsoft Academic Search

    Steven R. Oleson; Roger M. Myers; Craig A. Kluever; John P. Riehl; Francis M. Curran

    1995-01-01

    Solar electric propulsion (SEP) technology is currently being used for geostationary satellite station keeping to increase payload mass. Analyses show that advanced electric propulsion technologies can be used to obtain additional increases in payload mass by using these same technologies to perform part of the orbit transfer. In this work three electric propulsion technologies are examined at two power levels

  18. Geostationary Operational Environmental Satellite (GOES)-8 mission flight experience

    NASA Technical Reports Server (NTRS)

    Noonan, C. H.; Mcintosh, R. J.; Rowe, J. N.; Defazio, R. L.; Galal, K. F.

    1995-01-01

    The Geostationary Operational Environmental Satellite (GOES)-8 spacecraft was launched on April 13, 1994, at 06:04:02 coordinated universal time (UTC), with separation from the Atlas-Centaur launch vehicle occurring at 06:33:05 UTC. The launch was followed by a series of complex, intense operations to maneuver the spacecraft into its geosynchronous mission orbit. The Flight Dynamics Facility (FDF) of the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) was responsible for GOES-8 attitude, orbit maneuver, orbit determination, and station acquisition support during the ascent phase. This paper summarizes the efforts of the FDF support teams and highlights some of the unique challenges the launch team faced during critical GOES-8 mission support. FDF operations experience discussed includes: (1) The abort of apogee maneuver firing-1 (AMF-1), cancellation of AMF-3, and the subsequent replans of the maneuver profile; (2) The unexpectedly large temperature dependence of the digital integrating rate assembly (DIRA) and its effect on GOES-8 attitude targeting in support of perigee raising maneuvers; (3) The significant effect of attitude control thrusting on GOES-8 orbit determination solutions; (4) Adjustment of the trim tab to minimize torque due to solar radiation pressure; and (5) Postlaunch analysis performed to estimate the GOES-8 separation attitude. The paper also discusses some key FDF GOES-8 lessons learned to be considered for the GOES-J launch which is currently scheduled for May 19, 1995.

  19. Geostationary augmentation of global satellite navigation - 1991 update

    Microsoft Academic Search

    George V. Kinal; Jim Nagle

    1992-01-01

    The concept and recent developments of a civil geostationary overlay (augmentation) to GPS and GLONASS are presented. Navigation payloads will be carried on Inmarsat-3 satellites, and possibly on various other host satellites, i.e., Japanese and European. Studies, supplemented by demonstrations and tests utilizing communications band frequencies, are being carried out, to develop the ground system methods necessary to effectively and

  20. Advanced Propulsion for Geostationary Orbit Insertion and North-South Station Keeping

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; Myers, Roger M.; Kluever, Craig A.; Riehl, John P.; Curran, Francis M.

    1997-01-01

    Solar electric propulsion technology is currently being used for geostationary satellite station keeping. Analyses show that electric propulsion technologies can be used to obtain additional increases in payload mass by using them to perform part of the orbit transfer. Three electric propulsion technologies are examined at two power levels for geostationary insertion of an Atlas IIAS class spacecraft. The onboard chemical propulsion apogee engine fuel is reduced in this analysis to allow the use of electric propulsion. A numerical optimizer is used to determine the chemical burns that will minimize the electric propulsion transfer times. For a 1550-kg Atlas IIAS class payload, increases in net mass (geostationary satellite mass less wet propulsion system mass) of 150-800 kg are enabled by using electric propulsion for station keeping, advanced chemical engines for part of the transfer, and electric propulsion for the remainder of the transfer. Trip times are between one and four months.

  1. A statistical survey of ELF waves in a geostationary orbit

    Microsoft Academic Search

    M. Parrot; C. A. Gaye

    1994-01-01

    GEOS 2 is a geostationary satellite that was launched with a wave experiment. The data provided during its lifetime (approximately 3.5 years) constitute a unique set for the statistical study of electomagnetic and electrostatic waves at L = 6.6. The aim of this paper is to present maps of the average intensity of the electric and magnetic field. The location

  2. Remote sensing of aerosol and radiation from geostationary satellites

    Microsoft Academic Search

    Istvan Laszlo; Pubu Ciren; Hongqing Liu; Shobha Kondragunta; J. Dan Tarpley; Mitchell D. Goldberg

    2008-01-01

    The paper presents a high-level overview of current and future remote sensing of aerosol and shortwave radiation budget carried out at the US National Oceanic and Atmospheric Administration (NOAA) from the US Geostationary Operational Environmental Satellite (GOES) series. The retrievals from the current GOES imagers are based on physical principles. Aerosol and radiation are estimated in separate processing from the

  3. Geostationary satellite detection of bio mass burning in South America

    Microsoft Academic Search

    E. M. PRINS; W. P. MENZEL

    1992-01-01

    This paper presents the results of using Geostationary Operational Environmental Satellite (GOES) Visible Infrared Spin Scan Radiometer Atmospheric Sounder (VAS) data to monitor biomass burning associated with deforestation and grassland management in South America. The technique of Matson and Dozier has been adapted to GOES VAS short-wave and long-wave infrared window data to determine ihe size and temperature of fires

  4. AVIATION UTILIZATION OF GEOSTATIONARY SATELLITES FOR THE AUGMENTATION TO

    E-print Network

    Stanford University

    AVIATION UTILIZATION OF GEOSTATIONARY SATELLITES FOR THE AUGMENTATION TO GPS: RANGING AND DATA LINK currently under development by the Federal Aviation Administration (FAA). WAAS will provide corrections to aviation users for the GPS clock, its ephemeris, and for the delay in its signal as it passes through

  5. An approach to ground based space surveillance of geostationary on-orbit servicing operations

    NASA Astrophysics Data System (ADS)

    Scott, Robert (Lauchie); Ellery, Alex

    2015-07-01

    On Orbit Servicing (OOS) is a class of dual-use robotic space missions that could potentially extend the life of orbiting satellites by fuel replenishment, repair, inspection, orbital maintenance or satellite repurposing, and possibly reduce the rate of space debris generation. OOS performed in geostationary orbit poses a unique challenge for the optical space surveillance community. Both satellites would be performing proximity operations in tight formation flight with separations less than 500 m making atmospheric seeing (turbulence) a challenge to resolving a geostationary satellite pair when viewed from the ground. The two objects would appear merged in an image as the resolving power of the telescope and detector, coupled with atmospheric seeing, limits the ability to resolve the two objects. This poses an issue for obtaining orbital data for conjunction flight safety or, in matters pertaining to space security, inferring the intent and trajectory of an unexpected object perched very close to one's satellite asset on orbit. In order to overcome this problem speckle interferometry using a cross spectrum approach is examined as a means to optically resolve the client and servicer's relative positions to enable a means to perform relative orbit determination of the two spacecraft. This paper explores cases where client and servicing satellites are in unforced relative motion flight and examines the observability of the objects. Tools are described that exploit cross-spectrum speckle interferometry to (1) determine the presence of a secondary in the vicinity of the client satellite and (2) estimate the servicing satellite's motion relative to the client. Experimental observations performed with the Mont Mégantic 1.6 m telescope on co-located geostationary satellites (acting as OOS proxy objects) are described. Apparent angular separations between Anik G1 and Anik F1R from 5 to 1 arcsec were observed as the two satellites appeared to graze one another. Data reduction using differential angular measurements derived from speckle images collected by the 1.6 m telescope produced relative orbit estimates with better than 90 m accuracy in the cross-track and in-track directions but exhibited highly variable behavior in the radial component from 50 to 1800 m. Simulations of synthetic tracking data indicated that the radial component requires approximately six hours of tracking data for an Extended Kalman Filter to converge on an relative orbit estimate with less than 100 m overall uncertainty. The cross-spectrum approach takes advantage of the Fast Fourier Transform (FFT) permitting near real-time estimation of the relative orbit of the two satellites. This also enables the use of relatively larger detector arrays (>106 pixels) helping to ease acquisition process to acquire optical angular data.

  6. McIDAS-V: A powerful visualization and data analysis tool for geostationary environmental satellites

    NASA Astrophysics Data System (ADS)

    Achtor, T. H.; Rink, T.; Straka, W.; Feltz, J.

    2012-12-01

    The University of Wisconsin's Space Science and Engineering Center (SSEC) has been at the forefront in developing data analysis and visualization tools for environmental satellite and other geophysical data. The fifth generation of the Man-computer Interactive Data Access System (McIDAS-V) is a java-based, open-source, freely available system for researchers and algorithm developers that is being adapted and expanded for use with advanced geostationary environmental satellite observations. A key attribute of analysis and visualization systems is access to and display of a large variety of geophysical data. Providing these capabilities for numerous data types provides users with powerful tools for merging information, comparison of products and evaluation. McIDAS-V provides unique capabilities that support creative techniques for developing and evaluating algorithms, visualizing data and products in 4 dimensions, and validating results. For geostationary applications, McIDAS-V provides visualization and analysis support for GOES, MSG, MTSAT and FY2 data. NOAA is supporting the McIDAS-V development program for ABI imagery and products for the GOES-R/S series, which will bring an advanced multi-spectral imager into geostationary orbit. Used together, the geostationary environmental satellites provide the user community with detailed global coverage with rapid update cycles. This poster and demonstration will provide an overview of McIDAS-V with demonstrations of the data acquisition, visualization and analysis tools to support the international geostationary environmental satellite programs. It will also present results from several research projects involving current and future environmental satellites, demonstrating how the McIDAS-V software can be used to acquire satellite and ancillary data, create multi--spectral products using both scripting and interactive data manipulation tools, and evaluate output through on-board validation techniques.;

  7. Our Understanding of Space Weather features responsible for geostationary satellite anamolies (P39)

    Microsoft Academic Search

    G. Rajaram

    2006-01-01

    girija60@yahoo.com The topic of space weather effects on operational anomalies on spacecraft is one of considerable research investigation, with both pure and applied aspects. This is because of the very high costs involved in fabricating and operating spacecraft, and in insuring them against the harmful effects of space weather. This is more true for geostationary satellites than of low-orbiting spacecraft,

  8. Communications Satellite System by Using Moon Orbit Satellite Constellation

    Microsoft Academic Search

    Sang-Uk Lee; Jae-Hoon Kim; Seong-Pal Lee

    2003-01-01

    A communications satellite system placed in three-Lagrange points, L3, L4, and L5, of the restricted three-body problem in Earth-Moon system is proposed in this paper. LEO satellite constellation has been another choice of communications system. The proposed system which is alternatives of limited geostationary orbit resources, has some weak points such as long distance from the Earth, relatively expensive launch

  9. Modeling water and heat balance components of large territory for vegetation season using information from polar-orbital and geostationary meteorological satellites

    NASA Astrophysics Data System (ADS)

    Muzylev, Eugene; Startseva, Zoya; Uspensky, Alexander; Volkova, Elena; Kukharsky, Alexander; Uspensky, Sergey

    2015-04-01

    To date, physical-mathematical modeling processes of land surface-atmosphere interaction is considered to be the most appropriate tool for obtaining reliable estimates of water and heat balance components of large territories. The model of these processes (Land Surface Model, LSM) developed for vegetation period is destined for simulating soil water content W, evapotranspiration Ev, vertical latent LE and heat fluxes from land surface as well as vertically distributed soil temperature and moisture, soil surface Tg and foliage Tf temperatures, and land surface skin temperature (LST) Ts. The model is suitable for utilizing remote sensing data on land surface and meteorological conditions. In the study these data have been obtained from measurements by scanning radiometers AVHRR/NOAA, MODIS/EOS Terra and Aqua, SEVIRI/geostationary satellites Meteosat-9, -10 (MSG-2, -3). The heterogeneity of the land surface and meteorological conditions has been taken into account in the model by using soil and vegetation characteristics as parameters and meteorological characteristics as input variables. Values of these characteristics have been determined from ground observations and remote sensing information. So, AVHRR data have been used to build the estimates of effective land surface temperature (LST) Ts.eff and emissivity E, vegetation-air temperature (temperature at the vegetation level) Ta, normalized vegetation index NDVI, vegetation cover fraction B, the leaf area index LAI, and precipitation. From MODIS data the values of LST Tls, Å, NDVI, LAI have been derived. From SEVIRI data there have been retrieved Tls, E, Ta, NDVI, LAI and precipitation. All named retrievals covered the vast territory of the part of the agricultural Central Black Earth Region located in the steppe-forest zone of European Russia. This territory with coordinates 49°30'-54°N, 31°-43°E and a total area of 227,300 km2 has been chosen for investigation. It has been carried out for years 2009-2013 vegetation seasons. To provide the retrieval of Ts.eff, E, Ta, NDVI, B, and LAI the previously developed technologies of AVHRR data processing have been refined and adapted to the region of interest. The updated linear regression estimators for Ts.eff and Tà have been built using representative training samples compiled for above vegetation seasons. The updated software package has been applied for AVHRR data processing to generate estimates of named values. To verify the accuracy of these estimates the error statistics of Ts.eff and Ta derivation has been investigated for various days of named seasons using comparison with in-situ ground-based measurements. On the base of special technology and Internet resources the remote sensing products Tls, E, NDVI, LAI derived from MODIS data and covering the study area have been extracted from LP DAAC web-site for the same vegetation seasons. The reliability of the MODIS-derived Tls estimates has been confirmed via comparison with analogous and collocated ground-, AVHRR-, and SEVIRI-based ones. The prepared remote sensing dataset has also included the SEVIRI-derived estimates of Tls, E, NDVI, Ta at daylight and night-time and daily estimates of LAI. The Tls estimates has been built utilizing the method and technology developed for the retrieval of Tls and E from 15 minutes time interval SEVIRI data in IR channels 10.8 and 12.0 µm (classified as 100% cloud-free and covering the area of interest) at three successive times without accurate a priori knowledge of E. Comparison of the SEVIRI-based Tls retrievals with independent collocated Tls estimates generated at the Land Surface Analysis Satellite Applications Facility (LSA SAF, Lisbon, Portugal) has given daily- or monthly-averaged values of RMS deviation in the range of 2°C for various dates and months during the mentioned vegetation seasons which is quite acceptable result. The reliability of the SEVIRI-based Tls estimates for the study area has been also confirmed by comparing with AVHRR- and MODIS-derived LST estimates for the same seasons. The SEVIRI-derived values

  10. Development of an in-orbit refocusing mechanism for the Meteosat second-generation weather satellites

    Microsoft Academic Search

    Peter Verhoeff; H. A. van Mierlo; Ben C. Braam; J. Hopman; W. P. van Werhoven; Marco Le Kluse

    1998-01-01

    A Refocusing Mechanism (REM) has been designed and built for the SEVIRI instrument, the imager in the Meteosat Second Generation (MSG) satellite. The purpose of the mechanisms is in-orbit focal adjustment from its geostationary assembly which forms part of SEVIRI. As the MSG satellite observes the earth and its atmosphere from its geostationary orbit, the REM will be used to

  11. HISPASAT launch and early operations phases: Computation and monitoring of geostationary satellite positioning

    NASA Technical Reports Server (NTRS)

    Brousse, Pascal; Desprairies, Arnaud

    1993-01-01

    Since 1974, CNES, the French National Space Agency, has been involved in the geostationary launch and early operations phases (LEOP) of moving satellites from a transfer orbit delivered by a launcher to a geostationary point. During the operations and their preparation, the Flight Dynamics Center (FDC), part of CNES LEOP facilities, is in charge of the space mechanics aspects. What is noteworthy about the Spanish HISPASAT satellite positioning is that all the operations were performed on the customer's premises, and consequently the FDC was duplicated in Madrid, Spain. The first part of this paper is the FDC presentation: its role, its hardware configuration, and its space dynamics ground control system called MERCATOR. The second part of this paper details the preparation used by the FDC for the HISPASAT mission: hardware and software installation in Madrid, integration with the other entities, and technical and operational qualifications. The third part gives results concerning flight dynamics aspects and operational activities.

  12. Static and kinematic positioning using WADGPS from geostationary satellites

    NASA Astrophysics Data System (ADS)

    Cefalo, R.; Gatti, M.

    2003-04-01

    STATIC AND KINEMATIC POSITIONING USING WADGPS CORRECTIONS FROM GEOSTATIONARY SATELLITES Cefalo R. (1), Gatti M (2) (1) Department of Civil Engineering, University of Trieste, P.le Europa 1, 34127 Trieste, Italy, cefalo@dic.univ.trieste.it, (2) Department of Engineering, University of Ferrara, via Saragat 1, 44100 Ferrara, Italy, mgatti@ing.unife.it ABSTRACT. Starting from February 2000, static and kinematic experiments have been performed at the Department of Civil Engineering of University of Trieste, Italy and the Department of Engineering of University of Ferrara, Italy, using the WADGPS (Wide Area Differential GPS) corrections up linked by Geostationary Satellites belonging to the American WAAS and European EGNOS. Recently, a prototypal service by ESA (European Space Agency) named SISNet (Signal In Space through Internet), has been introduced using Internet to diffuse the messages up linked through AOR-E and IOR Geostationary Satellites. This service will overcome the problems relative to the availability of the corrections in urban areas. This system is currently under tests by the authors in order to verify the latency of the message and the applicability and accuracies obtainable in particular in dynamic applications.

  13. Development of unified propulsion system for geostationary satellite

    NASA Astrophysics Data System (ADS)

    Murayama, S.; Kobayashi, H.; Masuda, I.; Kameishi, M.; Miyoshi, K.; Takahashi, M.

    Japan's first Liquid Apogee Propulsion System (LAPS) has been developed for ETS-VI (Engineering Test Satellite - VI) 2-ton class geostationary satellite. The next largest (2-ton class) geostationary satellite, COMETS (Communication and Broadcasting Engineering Test Satellite), requires a more compact apogee propulsion system in order to increase the space for mission instruments. The study for such a propulsion system concluded with a Unified Propulsion System (UPS), which uses a common N2H4 propellant tank for both bipropellant apogee engines and monopropellant Reaction Control System (RCS) thrusters. This type of propulsion system has several significant advantages compared with popular nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) bipropellant satellite propulsion systems: The NTO/N2H4 apogee engine has a high specific impulse, and N2H4 thrusters have high reliability. Residual of N2H4 caused by propellant utilization of apogee engine firing (AEF) can be consumed by N2H4 monopropellant thrusters; that means a considerably prolonged satellite life.

  14. Land surface albedo based on GOES geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Matthews, J. L.; Lattanzio, A.; Hankins, B.; Knapp, K.; Privette, J. L.

    2012-12-01

    Land surface albedo is the fraction of incoming solar radiation reflected by the land surface, and therefore can be a sensitive indicator of environmental changes. To this end, surface albedo is identified as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). NOAA's National Climatic Data Center (NCDC) recently adapted the Geostationary Surface Albedo (GSA; Lattanzio and Govaerts, 2010) algorithm for use with GOES data in support of a global albedo initiative led by the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM). SCOPE-CM helps coordinate ECV production responding to GCOS, WMO, and CEOS goals. The GSA algorithm was developed jointly by EUMETSAT and Joint Research Centre (JRC) using a method proposed by Pinty et al. (2000) to determine surface albedo using day-time, cloud-free geostationary observations from a single visible band. For the GOES implementation, raw GOES observations are calibrated using International Satellite Cloud Climatology Project (ISCCP) coefficients. Surface angular anisotropy is determined through the inversion of the GSA radiative transfer model using multiple geostationary images collected over a day under different illumination conditions. The inversion process requires ancillary total column ozone and water vapor values, which are acquired from the 20th Century Reanalysis V2 data set. The GSA algorithm produces a 10-day composite surface albedo map. This product is initially being developed for the years 2000-2003. Product quality is being assessed through comparisons with MODIS products as well as ground-based measurements. NCDC is producing albedo products from both GOES-E (75°W) and GOES-W (135°W). These are being merged with like products from EUMETSAT based on METEOSAT (0° and 63°E) and from JMA based on the Geostationary Meteorological Satellite System (140°E). In the near future, NOAA's Climate Data Record Program will provide the albedo product over the entire GOES period of record (1978-present).

  15. Onboard Real-Time Absolute Radiometric Calibration for Thermal Infrared Channels of Chinese Geostationary Meteorological Satellites

    E-print Network

    Dery, Stephen

    Geostationary Meteorological Satellites JINJUN TONG Environmental Science and Engineering Program, University Calibration and Validation for Environmental Satellites, China Meteorological Administration, National Satellite Meteorology Center, Beijing, China STEPHEN J. DE´ RY Environmental Science and Engineering Program

  16. Viking satellite orbit determination

    Microsoft Academic Search

    C. E. Hildebrand; E. J. Christensen; D. H. Boggs; G. H. Born; H. Hokikian; J. F. Jordan; W. B. Howard

    1977-01-01

    During the summer of 1976, the two Viking spacecraft, each consisting of an orbiter-lander combination, were inserted into orbit about Mars. The paper describes the experiences of the Viking Satellite Orbit Determination Team in determining Mars centered ephemerides of the orbiters and positions of the landers from the two-way Doppler and range data, and synthesizes the different phases of the

  17. Positioning determination and communications using two geostationary satellites

    NASA Astrophysics Data System (ADS)

    Morikawa, Eihisa; Miura, Ryu; Kimura, Kazuhiro; Kawase, Seiichiro; Ohmori, Shingo; Matsumoto, Yasushi; Wakao, Masayoshi

    1992-07-01

    A hybrid satellite communication system has been developed which can provide both communications and positioning services in one system using two geostationary satellites. The experimental system consists of the ETS-V (150 deg E) and INMARSAT (180 deg E), a base earth station (Kashima Space Research Center, Japan), and mobile earth stations. The frequencies between the satellites and mobile stations are 1.6/1.5 GHz. The distinctive feature of this system is that position determination of the mobile earth stations and communication, such as voice and data transmission, can be carried out over the same channel at the same time. Another feature is that the frequency bandwidth of the system is very narrow compared to those of GPS and GEOSTAR. The two types of terminals developed for the experiments with this hybrid system use the single channel per carrier method and the spread spectrum method. An outline of the experimental system is presented, and the estimated positioning accuracy is described.

  18. CNES organization for station positioning of geostationary satellites

    NASA Technical Reports Server (NTRS)

    Dulac, Jean

    1993-01-01

    Since 1975, the Toulouse Space Centre (a technical establishment of the French Space Agency, CNES) has successfully brought 15 geostationary satellites on to station. During these 17 years of experience, an organization of human and material resources has been built up that ensures a very high level of reliability in the execution of these station positioning operations. The main characteristics of this organization are a rigourous definition of the roles and responsibilities of each person involved, very detailed operations documentation, and methodical preparation of the operations.

  19. The Geostationary Operational Environmental Satellite (GOES) Product Generation System

    NASA Technical Reports Server (NTRS)

    Haines, S. L.; Suggs, R. J.; Jedlovec, G. J.

    2004-01-01

    The Geostationary Operational Environmental Satellite (GOES) Product Generation System (GPGS) is introduced and described. GPGS is a set of computer programs developed and maintained at the Global Hydrology and Climate Center and is designed to generate meteorological data products using visible and infrared measurements from the GOES-East Imager and Sounder instruments. The products that are produced by GPGS are skin temperature, total precipitable water, cloud top pressure, cloud albedo, surface albedo, and surface insolation. A robust cloud mask is also generated. The retrieval methodology for each product is described to include algorithm descriptions and required inputs and outputs for the programs. Validation is supplied where applicable.

  20. Geostationary Orbit Surveillance Using the Unscented Kalman Filter and the Analytical Orbit Model

    NASA Astrophysics Data System (ADS)

    Roh, Kyoung-Min; Park, Eun-Seo; Choi, Byung-Kyu

    2011-09-01

    A strategy for geostationary orbit (or geostationary earth orbit [GEO]) surveillance based on optical angular observations is presented in this study. For the dynamic model, precise analytical orbit model developed by Lee et al. (1997) is used to improve computation performance and the unscented Kalman filer (UKF) is applied as a real-time filtering method. The UKF is known to perform well under highly nonlinear conditions such as surveillance in this study. The strategy that combines the analytical orbit propagation model and the UKF is tested for various conditions like different level of initial error and different level of measurement noise. The dependencies on observation interval and number of ground station are also tested. The test results shows that the GEO orbit determination based on the UKF and the analytical orbit model can be applied to GEO orbit tracking and surveillance effectively.

  1. The geostationary Earth radiation budget (GERB) instrument on EUMETSAT's MSG satellite

    NASA Astrophysics Data System (ADS)

    Sandford, M. C. W.; Allan, P. M.; Caldwell, M. E.; Delderfield, J.; Oliver, M. B.; Sawyer, E.; Harries, J. E.; Ashmall, J.; Brindley, H.; Kellock, S.; Mossavati, R.; Wrigley, R.; Llewellyn-Jones, D.; Blake, O.; Butcher, G.; Cole, R.; Nelms, N.; DeWitte, S.; Gloesener, P.; Fabbrizzi, F.

    2003-12-01

    Geostationary Earth radiation budget (GERB) is an Announcement of Opportunity Instrument for EUMETSAT's Meteosat Second Generation (MSG) satellite. GERB will make accurate measurements of the Earth Radiation Budget from geostationary orbit, provide an absolute reference calibration for LEO Earth radiation budget instruments and allow studies of the energetics of atmospheric processes. By operating from geostationary orbit, measurements may be made many times a day, thereby providing essentially perfect diurnal sampling of the radiation balance between reflected and emitted radiance for that area of the globe within the field of view. GERB will thus complement other instruments which operate in low orbit and give complete global coverage, but with poor and biased time resolution. GERB measures infrared radiation in two wavelength bands: 0.32-4.0 and 0.32- 30 ?m, with a pixel element size of 44 km at sub-satellite point. This paper gives an overview of the project and concentrates on the design and development of the instrument and ground testing and calibration, and lessons learnt from a short time scale low-budget project. The instrument was delivered for integration on the MSG platform in April 1999 ready for the proposed launch in October 2000, which has now been delayed probably to early 2002. The ground segment is being undertaken by RAL and RMIB and produces near real-time data for meteorological applications in conjunction with the main MSG imager—SEVERI. Climate research and other applications which are being developed under a EU Framework IV pilot project will be served by fully processed data. Because of the relevance of the observations to climate change, it is planned to maintain an operating instrument in orbit for at least 3.5 years. Two further GERB instruments are being built for subsequent launches of MSG.

  2. Simulation of the water regime for a vast agricultural region territory utilizing measurements from polar-orbital and geostationary meteorological satellites

    NASA Astrophysics Data System (ADS)

    Muzylev, Eugene; Uspensky, Alexander; Startseva, Zoya; Volkova, Elena; Kukharsky, Alexander; Uspensky, Sergey

    2013-04-01

    The model of land surface-atmosphere interaction has been developed to calculate the water and heat balance components for vast vegetation covered areas during the growing season. The model is adjusted to utilize estimates of the land surface and meteorological characteristics derived from satellite-based measurements of radiometers AVHRR/NOAA, MODIS/EOS Terra, Aqua, and SEVIRI/Meteosat-9. The studies have been conducted for the territory of the European Russia Central Black Earth Region (CCR) with area of 227,300 km2 comprising seven regions of the Russian Federation for years 2009-2012 vegetation seasons. The technologies of AVHRR and MODIS data thematic processing have been refined and adapted to the study region providing the retrieval of land surface temperature Tls and emissivity E, land-air temperature (temperature at vegetation cover level) Ta, normalized difference vegetation index NDVI, vegetation cover fraction B, as well as the leaf area index LAI. The updated linear regression estimators for Tls, Ta and LAI have been built using more representative training samples compiled for the above vegetation seasons. The updated software package has been applied for AVHRR data processing to generate named remote sensing products for various dates of the mentioned vegetation periods. On the base of special technology and Internet resources the remote sounding products (Tls, E, NDVI, LAI), derived from MODIS data and covering the CCR, have been downloaded from LP DAAC web-site for the same vegetation seasons. The new method and technology have been developed and adopted for the retrieval of Tls and E from SEVIRI data. The retrievals cover the region of interest and are produced at daylight and nighttime. Method provides the derivation of Tls and E from SEVIRI measurements carried out at three successive times (for example, at 11.00, 12.00, 13.00 UTC), classified as 100% cloud-free for the study region without accurate a priori knowledge of E. The validation of remote sensing data on Tls was carried out through comparison of SEVIRI-based Tls retrievals (after bias correction) with independent collocated Tls estimates generated at LSA SAF (Lisbon, Portugal). It gives monthly-averaged values of RMS deviation in the range of 1.1-2.1°C for various dates and times during the period June-August 2009-2012. In addition the new method and technology have been also developed and tested for the Ta retrievals from SEVIRI data at daylight and nighttime. To derive Ta, the SEVIRI-based Tls estimates were used together with previously found correlation relationship between Tls and Ta. A comparison with collocated in-situ Ta observations, made at the CCR territory weather shelters, gives RMS errors in the range 1.8-2.9°C for the standard synoptic times and 2009-2012 summer periods. The error level is comparable to that inherent for the best foreign analogues as well as for numerical weather forecasting schemes. Developed techniques to assimilate remote sensing data in the model include the following: - replacement the values of the model parameters LAI and B, determined by observations at agricultural meteorological stations, by their satellite-derived estimates. Adequacy of such replacement has been confirmed by the results of comparing time behaviors of LAI built by ground- and satellite-based data, as well as the ground-measured and satellite-derived values of Tls and Ta, and modeled and measured values of evapotranspiration Ev and soil moisture content W. - entering the values of Tls and Ta retrieved from all aforementioned satellite data into the model as the input variables instead of the respective ground-measured temperatures. Availability of the SEVIRI data of fine temporal resolution creates opportunity to calculate the water and heat balance components quite accurately. However, the lack of the long continuous SEVIRI data series (because of the cloudiness) restricts this opportunity in a large extent. - taking into account spatial variability of vegetation and meteorological characteristics when calculating the water and hea

  3. Advanced Baseline Sounder (ABS) for future Geostationary Operational Environmental Satellites (GOES-R and beyond)

    E-print Network

    Li, Jun

    Advanced Baseline Sounder (ABS) for future Geostationary Operational Environmental Satellites (GOES-R Satellites (starting with GOES-R in 2012). ABS/HES will have thousands of channels with widths on the order

  4. Los Alamos energetic particle sensor systems at geostationary orbit

    SciTech Connect

    Baker, D.N.; Aiello, W.; Asbridge, J.R.; Belian, R.D.; Higbie, P.R.; Klebesadel, R.W.; Laros, J.G.; Tech, E.R.

    1985-01-01

    The Los Alamos National Laboratory has provided energetic particle sensors for a variety of spacecraft at the geostationary orbit (36,000 km altitude). The sensor system called the Charged Particle Analyzer (CPA) consists of four separate subsystems. The LoE and HiE subsystems measure electrons in the energy ranges 30 to 300 keV and 200 to 2000 keV, respectively. The LoP and HiP subsystems measure ions in the ranges 100 to 600 keV and 0.40 to 150 MeV, respectively. A separate sensor system called the spectrometer for energetic electrons (SEE) measures very high-energy electrons (2 to 15 MeV) using advanced scintillator design. In this paper we describe the relationship of operational anomalies and spacecraft upsets to the directly measured energetic particle environments at 6.6 R/sub E/. We also compare and contrast the CPA and SEE instrument design characteristics with the next generation of Los Alamos instruments to be flown at geostationary altitudes.

  5. Passive Radiator For Cooling IR Detectors In Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Grigg, R.; Havey, K.; Meyers, J.

    1985-12-01

    This paper presents an approach to the design, analysis, fabrication, and a test of a development model of 100 K passive space radiator for a geostationary meteorological satellite. Significant design considerations include the importance of heat-leak control at low temperatures and the importance of a well devised plan for elimination and control of moisture and contaminants. Fabrication issues include the ability of the design to be compatible with spacecraft assembly as well as to accommodate disassembly for repair or access to the focal plane. The results of a test of the development model are presented. The data correlation process is discussed and the need for a good means of determination of surface properties at cold temperatures is identified. A summary of recommended design and fabrication features is presented.

  6. Feasibility study of LEO, GEO and Molniya orbit based satellite solar power station for some identified sites in India

    Microsoft Academic Search

    Kalpana Chaudhary; Babau R. Vishvakarma

    2010-01-01

    The analysis of satellite solar power station (SSPS) is carried out for some specified locations (Delhi, Mumbai, Kolkata and Bengaluru) in India and consequently the performance of the system is evaluated for geostationary earth orbit (GEO) based SSPS, low earth orbit (LEO) based SSPS and Molniya (quasi geostationary) orbit based SSPS for sites located at different latitudes. The analysis of

  7. Differential spacecraft charging on the geostationary operational environmental satellites

    NASA Technical Reports Server (NTRS)

    Farthing, W. H.; Brown, J. P.; Bryant, W. C.

    1982-01-01

    Subsystems aboard the Geostationary Operational Environmental Satellites 4 and 5 showed instances of anomalous changes in state corresponding to false commands. Evidence linking the anomalous changes to geomagnetic activity, and presumably static discharges generated by spacecraft differential charging induced by substorm particle injection events is presented. The anomalies are shown to be correlated with individual substorms as monitored by stations of the North American Magnetometer Chain. The relative frequency of the anomalies is shown to be a function of geomagnetic activity. Finally a least squares fit to the time delay between substorm initiation and spacecraft anomaly as a function of spacecraft local time is shown to be consistent with injected electron populations with energy in the range 10 keV to 15 keV, in agreement with present understanding of the spacecraft charging mechanism. The spacecraft elements responsible for the differential charging were not satisfactorily identified. That question is currently under investigation.

  8. Using Geostationary Communications Satellites as a Sensor: Telemetry Search Algorithms

    NASA Astrophysics Data System (ADS)

    Cahoy, K.; Carlton, A.; Lohmeyer, W. Q.

    2014-12-01

    For decades, operators and manufacturers have collected large amounts of telemetry from geostationary (GEO) communications satellites to monitor system health and performance, yet this data is rarely mined for scientific purposes. The goal of this work is to mine data archives acquired from commercial operators using new algorithms that can detect when a space weather (or non-space weather) event of interest has occurred or is in progress. We have developed algorithms to statistically analyze power amplifier current and temperature telemetry and identify deviations from nominal operations or other trends of interest. We then examine space weather data to see what role, if any, it might have played. We also closely examine both long and short periods of time before an anomaly to determine whether or not the anomaly could have been predicted.

  9. Geostationary orbits from mid-latitude launch sites via lunar gravity assist

    NASA Astrophysics Data System (ADS)

    Graziani, F.; Castronuovo, M. M.; Teofilatto, P.

    The out-of-plane maneuver, necessary to acquire a geostationary orbit from launch sites that are at some degrees of latitude, makes the cost of such a mission very high. In this paper, we present a trajectory design for reaching a geostationary orbit from a mid-latitude launch base, with a consistent saving of propellant. This has been obtained using a lunar gravity assist (g.a.) to change the high inclination of the satellite orbit and, at the same time, to raise the perigee to the geosynchronous height. The Moon g.a. has been designed, describing the physical process by means of Opik's method. This is an analytical approximation technique which allows computation of outcome of planetary close encounters in a simple, but accurate, way. The trajectory resulting from this preliminary study has been used as a starting point for a numerical integration, using Everhart's integrator RADAU. We considered also the launch from Cape Canaveral (28.5 deg North), finding a small saving of V. The mission sequences are described and compared to other traditional trajectory designs.

  10. A condensed orbital history of Intelsat satellites

    NASA Astrophysics Data System (ADS)

    Walker, J. G.

    1984-03-01

    Intelsat, first established in 1964, has launched a total of 33 satellites between 1965 and 1983, including the Intelsat I, II, III, IV, IV-A and V series. Another 14 satellites, the Intelsat V-A and VI series, are under contract. Geostationary satellite service began in 1965 with the launch of Intelsat I over the Atlantic region. Launches of Intelsat II F-2 and Intelsat III F-3 over the Pacific and Indian Oceans followed in 1967 and 1969. Comsat managed the satellite system until Intelsat had established its own international staff in 1979. The Intelsat system's primary purupose is to provide transmission for public international communication traffic. As international communications increase, provision of spare satellites becomes important in the event of a failure in orbit. All Intelsat satellites operate on the 4 and 6 GHz frequency bands, while Intelsat V and subsequent satellites are also equipped to operate in the 11 and 14 GHz bands and, according to their designations, may be equipped to relay maritime traffic through Inmarsat. Despite several in-orbit incidents such as hydrogen peroxide propellant leakage, nickel-cadium battery deterioration, and uncommanded switching of electronic systems due to electrostatic discharges, it is concluded that the orbital history of Intelsat satellites has proved to be an outstanding success over the past 18 years. A comprehensive chart delineating the chronological evolution of the satellites is included.

  11. Debris in the geostationary orbit ring, the endless shooting gallery: The necessity for a disposal policy

    NASA Technical Reports Server (NTRS)

    Suddeth, D. H.

    1985-01-01

    NASA is considering establishing a policy for the limitation of the physical crowding of the geostationary orbit. The proposed policy is intended to address the following issues: (1) deal only with geostationary altitudes; (2) illustrate the unique value and usefulness of the geostationary orbit ring; (3) describe the orbital dynamics as simply as possible; (4) describe the current spacecraft and debris situation; (5) briefly review current industry and agency policies; (6) project future trends of physical crowding with the present nonpolicy; (7) propose solutions that can be implemented in the near future; and (8) use previous work as much as desirable.

  12. Our Understanding of Space Weather features responsible for geostationary satellite anamolies (P39)

    NASA Astrophysics Data System (ADS)

    Rajaram, G.; et al.

    2006-11-01

    girija60@yahoo.com The topic of space weather effects on operational anomalies on spacecraft is one of considerable research investigation, with both pure and applied aspects. This is because of the very high costs involved in fabricating and operating spacecraft, and in insuring them against the harmful effects of space weather. This is more true for geostationary satellites than of low-orbiting spacecraft, as the former operate in the high-risk environment of the Earth’s outer radiation belts, with its large vagaries in spatial and time variations of high- energy electron and proton distributions (BAKER 2003). Without doubt, plasma and magnetic field emissions from active regions on the Sun are the root cause for spacecraft anomalies. Our study for 2005 shows that over 95% of anomalies can be related to some definite activity on the Sun, ranging from high-speed solar wind streams with their 27-day recurrence patterns/coronal holes/coronal mass ejections preceded by X or M type of flares/and magnetic cloud events. The most energetic solar activity events are generally accompanied by a large rise in solar MeV proton densities at geo-stationary orbit (WILKINSON 1994), and they account for definite anomalies classified as SEU (Single Event Upsets which most often are reversible through resetting commands). Any particles in the low energy ranges (eV and keV, and these could be of magnetospheric or ionospheric origin), are believed to cause external charging effects in exposed parts of the spacecraft such as solar power arrays and power cables. These mainly result in power losses which are debilitating over a period of time. The most dangerous and often irrecoverable damage is due to electronics in the 1-5 MeV range which cause deep dielectric discharge of arc type in semi-conductors comprising spacecraft instruments. Following major solar activity, the populations of these rise to more than (5x103) particles/cm2.ster.sec, with large spatial and time variations (LOVE et al. 2000). When the influence of these relativistic electrons in the neighborhood of geo-stationary spacecraft builds up to values exceeding 108/cm2.ster.day, satellite anomalies invariably occur.Our study finds that these ‘Relativistic electron events’ accompanied by satellite anomalies invariably occur following sharp, well-defined shocks in the inter-planetary medium, and we are trying to understand the relationship between the two. We also notice that anomalies due to space weather effects are very satellite-specific, with differing threshold values seen for different satellites.

  13. CHRONOS: Time Resolved Atmospheric Pollution Observations Commercially Hosted in Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Edwards, D. P.; Chronos Science Team

    2011-12-01

    This presentation describes the CHRONOS (Commercially Hosted spectroRadiometer Observations and New Opportunities for Science) mission proposed to the NASA Earth Venture-2 program. The primary goal of this mission is to measure atmospheric pollutants carbon monoxide and methane from geostationary orbit concentrating on North America with high spatiotemporal (hourly at 8 km) resolution. This will provide unique insights into pollutant sources, transport, chemical transformations and climate impact. In addition to significantly improved understanding of the underlying processes determining atmospheric composition, CHRONOS observations will also find direct societal applications for air quality regulation and forecasting. CHRONOS is partnering with private industry to provide accommodation for the instrument as a commercially hosted payload on a telecommunications satellite. The gas correlation radiometry multispectral measurement technique has a demonstrated heritage in the low-Earth orbit Terra/Measurement of Pollution in The Troposphere (MOPITT) instrument that now provides more than a decade of observations. Providing these observations from a geostationary vantage point was also a recommendation of the Decadal Survey in the context of the GEO-CAPE mission.

  14. Satellite-to-satellite tracking orbit determination

    Microsoft Academic Search

    B. T. Fang

    1978-01-01

    In the 1980's, low-earth-satellite orbits will be determined from one-way or relayed range and range-rate measurements to high-altitude orbiting spacecraft such as the two geo-synchronous satellites in the NASA Tracking and Data Relay Satellite System (TDRSS) and the 24 twelve-hour period, 63 deg inclination spacecraft in the DOD Global Positioning System (GPS). In this study, error analysis methods for satellite-to-satellite

  15. Early fire detection system based on multi-temporal images of geostationary and polar satellites

    Microsoft Academic Search

    Evaristo Cisbani; Antonio Bartoloni; Marco Marchese; G. Efisei; Antonello Salvati

    2002-01-01

    A new, early fire automated alarm technique based on multi-temporal and multi-spectral analysis of satellite data is presented; it combines the multi-spectral capabilities of the TERRA\\/MODIS polar satellite to the high temporal frequency of the GOES\\/IMAGER geostationary satellite.

  16. Relativistic electrons near geostationary orbit: Evidence for internal magnetospheric acceleration

    SciTech Connect

    Baker, D. N.; Blake, J. B.; Callis, L. B.; Belian, R. D.; Cayton, T. E.

    1989-06-01

    At times, relativistic electron fluxes in Earth's outer magnetosphere are not obviously related to an external (Jovian or solar) source. This finding suggests that an internal magnetospheric acceleration mechanism may operate under some circumstances. A possible mechanism identified for Jupiter's magnetosphere could also be considered in the terrestrial case. Such a model requires the substorm- generation of a spectrally-soft electron component with subsequent inward radial diffusion (violating the third adiabatic invariant). A large electron energy gain transverse to the magnetic field occurs in this process. Eventually, deep within the magnetosphere, substantial pitch angle scattering occurs violating all adiabatic invariants. Then, at low L-values, there occurs an energy-preserving outward transport of energetic electrons near the mirror points. This leads to a return of the accelerated population to the outer magnetosphere. Such low-altitude processes should result in ''conic'' or ''butterfly'' pitch angle distributions at very high energies as the electrons execute trans-L diffusion at the mirror altitudes and then are magnetically focussed near the equator. Data collected concurrently at geostationary orbit at three widely-spaced local times during a relativisic electron event show a butterfly pitch angle distribution, while lower energy electrons simultaneously show pancake-like distributions. The butterfly pitch angle distributions appear in /similar to/25% of the examined relativistic electron events, thereby providing support for acceleration by a recirculation process. /copyright/ American Geophysical Union 1989

  17. The long-term orbit plane prediction for uncontrolled distant satellites

    Microsoft Academic Search

    C. Ulivieri; A. Agneni; L. Anselmo; A. Foni

    1989-01-01

    A semianalytical model which significantly reduces the computer time requirements of current numerical orbit integrators is presently used to investigate the orbit-plane evolution of high-altitude earth satellites, under lunisolar gravitational influence and in conjunction with the principal zonal harmonic of the earth's gravitational field. Model accuracy is assessed through a comparison of geostationary satellite model predictions with actual tracking measurement

  18. SATELLITE CONSTELLATION NETWORKS The path from orbital geometry through network topology to

    E-print Network

    Wood, Lloyd

    for Communication Systems Research, University of Surrey; software engineer, Cisco Systems Ltd. Abstract: Satellite communication services; a satellite in geostationary orbit above the Equator cannot see more than 30. Satellite constellations have been proposed and implemented for use in communications, including networking

  19. Estimation of land surface temperature from a Geostationary Operational Environmental Satellite (GOES-8)

    E-print Network

    Sun, Donglian

    approach used for deriving Sea Surface Temperature (SST), while the other is a three-channel algorithmEstimation of land surface temperature from a Geostationary Operational Environmental Satellite Operational Environmental Satellite (GOES) to enable frequent estimate of Land Surface Temperature (LST

  20. Preliminary verification results of the geostationary ocean color satellite data processing software system

    NASA Astrophysics Data System (ADS)

    Han, Hee-Jeong; Ryu, Joo-Hyung; Cho, Seongick; Yang, Chan-Su; Ahn, Yu-Hwan

    2010-10-01

    The data processing software system of Geostationary Ocean Color Imager (GOCI) is composed of the image preprocessing system (IMPS) and the GOCI data processing system (GDPS). IMPS generate GOCI level 1B from raw satellite data and GDPS is the post-processing system to generate GOCI level 2. IMPS have a radiometric correction module as IRCM and a geometric correction module named as INRSM. The former is focused on equipment's mechanical noise reduction and radiometric accuracy and the latter image navigation and image registration accuracy by landmark matching method and image mosaic method. GDPS have the atmospheric correction algorithms, as the spectral shape matching method (SSMM) and the sun glint correction algorithm (SGCA), and BRDF algorithm to solve bi-directional problem. Several Case-II water analytical algorithms, like chlorophyll concentration, suspended sediment and dissolved organic matter, are contained in GDPS. Also, GDPS will generate the value added product like water quality, fishery ground information, water current vector, etc. During in-orbit test period planned six months after successful launch of satellite, IMPS and GDPS will be verified with respect to those requirements and algorithms and functionality and accuracy by pre-defined test procedure like test, inspection, demonstration. And then those configuration parameters will be modified and the algorithm descriptions will be updated. In this paper, we will present the preliminary analyzed results of data processing system test and update planning during in-orbit test.

  1. The future role of relay satellites for orbital telerobotics

    NASA Astrophysics Data System (ADS)

    Stoll, Enrico; Letschnik, Jürgen; Wilde, Markus; Saenz-Otero, Alvar; Varatharajoo, Renuganth; Artigas, Jordi

    2012-10-01

    Orbital robotics focuses on a variety of applications, as e.g. inspection and repair activities, spacecraft construction or orbit corrections. On-Orbit Servicing (OOS) activities have to be closely monitored by operators on ground. A direct contact to the spacecraft in Low Earth Orbit (LEO) is limiting the operational time of the robotic application. Therefore, geostationary satellites are desirable to relay the OOS signals and extend the servicing time window. A geostationary satellite in the communication chain not only introduces additional boundary conditions to the mission but also increases the time delay in the system. The latter is not very critical if the servicer satellite is operating autonomously. However, if the servicer is operating in a supervised control regime with a human in the loop, the increased time delay will have an impact on the operator's task performance. This paper describes the challenges, which have to be met when utilizing a relay satellite for orbital telerobotics. It shows a series of ground experiments that were undertaken with a relay satellite in the communication chain to simulate the end-to-end system. This case study proves that complex robotic applications in Low Earth Orbit (LEO) are controllable by human operators on ground.

  2. Effects of Surface Albedo on Smoke Detection Through Geostationary Satellite Imagery in the Hazard Mapping System (HMS)

    NASA Astrophysics Data System (ADS)

    Salemi, A.; Ruminski, M. G.

    2012-12-01

    The Satellite Analysis Branch (SAB) of NOAA/NESDIS uses geostationary and polar orbiting satellite imagery to identify fires and smoke throughout the continental United States. The fires and smoke are analyzed daily on the Hazard Mapping System (HMS) and made available via the internet in various formats. Analysis of smoke plumes generated from wildfires, agricultural and prescribe burns is performed with single channel visible imagery primarily from NOAA's Geostationary Operational Environmental Satellite (GOES) animations. Identification of smoke in visible imagery is complicated by the presence of clouds, the viewing angle produced by the sun, smoke, satellite geometry, and the surface albedo of the ground below the smoke among other factors. This study investigates the role of surface albedo in smoke detection. LIght Detection And Ranging (LIDAR) instruments are capable of detecting smoke and other aerosols. Through the use of ground and space based LIDAR systems in areas of varying albedo a relationship between the subjective analyst drawn smoke plumes versus those detected by LIDAR is established. The ability to detect smoke over regions of higher albedo (brighter surface, such as grassland, scrub and desert) is diminished compared to regions of lower albedo (darker surface, such as forest and water). Users of the HMS smoke product need to be aware of this limitation in smoke detection in areas of higher albedo.

  3. Equilibrium Positions and Stability of 24Hour Satellite Orbits

    Microsoft Academic Search

    Leon Blitzer

    1965-01-01

    The influence of the entire spectrum of tesseral harmonics of the geopotentiM on synchronous (24-hour) satellite orbits of small eccentricity and inclination is investigated. The dominant forces are due to the longitude-dependent term (J=) associated with the earth's equatorial ellipticity. With the Jterm alone there exist four possible geostationary points, symmetrically situated on the extensions of the principal axes of

  4. A Geostationary Satellite Constellation for Observing Global Air Quality: Status of the CEOS Activity

    NASA Astrophysics Data System (ADS)

    Al-Saadi, J. A.; Zehner, C.

    2011-12-01

    Several countries and space agencies are currently planning to launch geostationary satellites in the 2017-2022 time frame to obtain atmospheric composition measurements for characterizing anthropogenic and natural distributions of tropospheric ozone, aerosols, and their precursors, which are important factors in understanding air quality and climate change. While a single geostationary satellite can view only a portion of the globe, it is possible for a minimum of three geostationary satellites, positioned to view Europe/Middle East/Africa, Asia/Australasia, and the Americas, to collectively provide near-global coverage. Harmonizing the planned geostationary missions to be contemporaneous and have common observing capabilities and data distribution protocols would synergistically enable critically needed understanding of the interactions between regional and global atmospheric composition and of the implications for air quality and climate. Such activities would directly address societal benefit areas of the Global Earth Observation System of Systems (GEOSS), including Health, Energy, Climate, Disasters, and Ecosystems, and are responsive to the requirements of each mission to provide advanced user services and societal benefits. Over the past 2 years, the Atmospheric Composition Constellation (ACC) of the Committee on Earth Observation Satellites (CEOS) has developed a white paper describing such collaboration and the benefits to be derived from it. The resulting ACC recommendations were endorsed by CEOS in May 2011. Here we will present an update on collaborative activities and next steps. This presentation is envisioned to serve as an introduction to the oral sessions associated with Session A.25.

  5. Land Surface Temperature Estimation from the Next Generation of Geostationary Operational Environmental Satellites: GOES M Q

    Microsoft Academic Search

    Donglian Sun; Rachel T. Pinker; Jeffery B. Basara

    2004-01-01

    The next generation of Geostationary Operational Environmental Satellites (GOES M Q) will have only one thermal window channel instead of the current two split-window thermal channels. There is a need to evaluate the usefulness of this new configuration to retrieve parameters that presently are derived by utilizing the split-window characteristics. Two algorithms for deriving land surface temperatures (LSTs) from the

  6. Investigation of single-hop connections between user terminals in geostationary mobile satellite communication systems

    Microsoft Academic Search

    Kazuhito Ebina; Nobuyuki Kataoka; Masazumi Ueba; Hideki Mizuno

    2001-01-01

    The number of subscribers in geostationary mobile satellite communication systems has been increasing, as a result of the increase voice communication between user terminals. In this situation, there is a strong demand to improve the communication quality of the double-hop connection between two user terminals. As an means of reducing the voice delay, we developed four single-hop connection methods in

  7. Preliminary verification results of the geostationary ocean color satellite data processing software system

    Microsoft Academic Search

    Hee-Jeong Han; Joo-Hyung Ryu; Seongick Cho; Chan-Su Yang; Yu-Hwan Ahn

    2010-01-01

    The data processing software system of Geostationary Ocean Color Imager (GOCI) is composed of the image preprocessing system (IMPS) and the GOCI data processing system (GDPS). IMPS generate GOCI level 1B from raw satellite data and GDPS is the post-processing system to generate GOCI level 2. IMPS have a radiometric correction module as IRCM and a geometric correction module named

  8. Attitude determination for three-axis stabilized geostationary meteorological satellite image navigation

    Microsoft Academic Search

    Yaguang Wu; Zhigang Wang

    2005-01-01

    To achieve the high accuracy of attitude determination for three-axis stabilized geostationary meteorological satellite image navigation, a new approach combined gyro with star trackers is proposed, and a real-time algorithm for attitude estimation is designed. This algorithm begins with a prediction for angular rate model errors induced by gyro drifting error, and ends with the extended Kalman filtering (EKF) for

  9. Long Waves in the Eastern Equatorial Pacific Ocean: A View from a Geostationary Satellite

    Microsoft Academic Search

    Richard Legeckis

    1977-01-01

    During 1975, westward-moving long waves with a period of about 25 days and a wavelength of 1000 kilometers were observed at a sea surface temperature front in the equatorial Pacific on infrared images obtained by a geostationary environmental satellite system. The absence of these waves during 1976, and the above-average equatorial sea surface temperatures during 1976, may be related to

  10. Feasibility study for Japanese Air Quality Mission from Geostationary Satellite: Infrared Imaging Spectrometer

    NASA Astrophysics Data System (ADS)

    Sagi, K.; Kasai, Y.; Philippe, B.; Suzuki, K.; Kita, K.; Hayashida, S.; Imasu, R.; Akimoto, H.

    2009-12-01

    A Geostationary Earth Orbit (GEO) satellite is potentially able to monitor the regional distribution of pollution with good spatial and temporal resolution. The Japan Society of Atmospheric Chemistry (JSAC) and the Japanese Space Exploration Agency (JAXA) initiated a concept study for air quality measurements from a GEO satellite targeting the Asian region [1]. This work presents the results of sensitivity studies for a Thermal Infrared (TIR) (650-2300cm-1) candidate instrument. We performed a simulation study and error analysis to optimize the instrumental operating frequencies and spectral resolution. The scientific requirements, in terms of minimum precision (or error) values, are 10% for tropospheric O3 and CO and total column of HN3 and nighttime HNO2 and 25% for O3 and CO with separating 2 or 3 column in troposphere. Two atmospheric scenarios, one is Asian background, second is polluted case, were assumed for this study. The forward calculations and the retrieval error analysis were performed with the AMATERASU model [2] developed within the NICT-THz remote sensing project. Retrieval error analysis employed the Optimal Estimation Method [3]. The geometry is off-nadir observation on Tokyo from the geostationary satellite at equator. Fine spectral resolution will allow to observe boundary layer O3 and CO. We estimate the observation precision in the spectral resolution from 0.1cm-1 to 1cm-1 for 0-2km, 2-6km, and 6-12km. A spectral resolution of 0.3 cm-1 gives good sensitivity for all target molecules (e.g. tropospheric O3 can be detected separated 2 column with error 30%). A resolution of 0.6 cm-1 is sufficient to detect tropospheric column amount of O3 and CO (in the Asian background scenario), which is within the required precision and with acceptable instrumental SNR values of 100 for O3 and 30 for CO. However, with this resolution, the boundary layer ozone will be difficult to detect in the background abundance. In addition, a spectral resolution of 0.6 cm-1 is sufficient to retrieve the total column of HNO3 and NO2 with a precision better than 10%. IR measurements will thus be useful for tropospheric pollution monitoring. Reference: [1] http://www.stelab.nagoya-u.ac.jp/ste-www1/div1/taikiken/eisei/eisei2.pdf, Japanese version only [2] P. Baron et al., AMATERASU: Model for Atmospheric TeraHertz Radiation Analysis and Simulation, Journal of the National Institute of Information and Communications Technology, 55(1), 109-121, 2008. [3] Rodgers. C. D., Inverse methods for atmospheric sounding: Theory and practice, World Scientific, Singapore (2000).

  11. Long-term orbit prediction of high-altitude earth satellites

    Microsoft Academic Search

    Carlo Ulivieri; A. Agneni

    1986-01-01

    The long-period evolution of the orbital plane of uncontrolled high-altitude Earth satellites, under luni-solar gravitational effects, which can be independently treated with a good approximation from the other long-term perturbative effects was investigated. Since computer programs usually employed for orbit prediction during the satellite operational life are very time-consuming, a semianalytical model for geostationary orbits, that reduces computer time and

  12. Orbits R Us!

    NSDL National Science Digital Library

    This site introduces the principle of geosynchronous orbits and geostationary weather satellites in non-technical terms. Several animations show how they work. The GOES (Geostationary Operational Environmental Satellite) and POES (Polar-orbiting Operational Environmental Satellites) satellite programs at NASA and NOAA are briefly explained.

  13. Hybrid system of communication and positioning determination using two geostationary satellites

    NASA Astrophysics Data System (ADS)

    Morikawa, Eihisa; Matsumoto, Yasushi; Ohmori, Shingo; Wakao, Masayoshi

    1991-04-01

    A new hybrid satellite system has been developed which can provide both communications and positioning services in one system using two geostationary satellites. The first distinctive feature is that location information can be provided by transmitting and receiving ranging signals over the same channel that is used for voice communication employing two geostationary satellites. The second is that the frequency bandwidth of the system is very narrow compared with those of the GPS (Global Positioning System) and GEOSTAR. The experimental system, equipment configuration, and positioning accuracy are discussed. The dominant error factor of position determination was found to be the tracking error of the delay-lock loop of a receiver, and it was estimated to be several meters and several tens of meters in the spread-spectrum and single-channel-per-carrier systems, respectively. Taking account of satellite motions of ETS-V and INMARSAT, a positioning accuracy of several hundreds of meters was found in Pacific Ocean areas.

  14. Comparison of Cloud Properties from CALIPSO-CloudSat and Geostationary Satellite Data

    NASA Technical Reports Server (NTRS)

    Nguyen, L.; Minnis, P.; Chang, F.; Winker, D.; Sun-Mack, S.; Spangenberg, D.; Austin, R.

    2007-01-01

    Cloud properties are being derived in near-real time from geostationary satellite imager data for a variety of weather and climate applications and research. Assessment of the uncertainties in each of the derived cloud parameters is essential for confident use of the products. Determination of cloud amount, cloud top height, and cloud layering is especially important for using these real -time products for applications such as aircraft icing condition diagnosis and numerical weather prediction model assimilation. Furthermore, the distribution of clouds as a function of altitude has become a central component of efforts to evaluate climate model cloud simulations. Validation of those parameters has been difficult except over limited areas where ground-based active sensors, such as cloud radars or lidars, have been available on a regular basis. Retrievals of cloud properties are sensitive to the surface background, time of day, and the clouds themselves. Thus, it is essential to assess the geostationary satellite retrievals over a variety of locations. The availability of cloud radar data from CloudSat and lidar data from CALIPSO make it possible to perform those assessments over each geostationary domain at 0130 and 1330 LT. In this paper, CloudSat and CALIPSO data are matched with contemporaneous Geostationary Operational Environmental Satellite (GOES), Multi-functional Transport Satellite (MTSAT), and Meteosat-8 data. Unlike comparisons with cloud products derived from A-Train imagers, this study considers comparisons of nadir active sensor data with off-nadir retrievals. These matched data are used to determine the uncertainties in cloud-top heights and cloud amounts derived from the geostationary satellite data using the Clouds and the Earth s Radiant Energy System (CERES) cloud retrieval algorithms. The CERES multi-layer cloud detection method is also evaluated to determine its accuracy and limitations in the off-nadir mode. The results will be useful for constraining the use of the passive retrieval data in models and for improving the accuracy of the retrievals.

  15. A geostationary satellite tracking system for small-sized earth stations

    Microsoft Academic Search

    H. Ohashi; M. Iguchi; Y. Hashimoto

    1983-01-01

    A geostationary satellite auto-tracking system which is a hybrid system of step-track and program-track is described. This auto-tracking system is suitable for small-sized earth stations used in 20\\/30 GHz band or more higher frequency bands. In fine weather, the step-track mode is selected and antenna is driven step by step and positioned automatically to maximize the received satellite beacon signal

  16. Next-generation Geostationary Operational Environmental Satellite (GOES-R series): a space segment overview

    Microsoft Academic Search

    Alexander Krimchansky; Dino Machi; Sandra A. Cauffman; Martin A. Davis

    2004-01-01

    The next-generation National Oceanic and Atmospheric Administration (NOAA) Geostationary Operational Environmental Satellite (GOES-R series) is currently being developed by NOAA in partnership with the National Aeronautics and Space Administration (NASA). The GOES-R series satellites represents a significant improvement in spatial, temporal, and spectral observations (several orders of magnitude) over the capabilities of the currently operational GOES-I\\/M series and GOES-N series

  17. Martian satellite orbits and ephemerides

    NASA Astrophysics Data System (ADS)

    Jacobson, R. A.; Lainey, V.

    2014-11-01

    We discuss the general characteristics of the orbits of the Martian satellites, Phobos and Deimos. We provide a concise review of the various descriptions of the orbits by both analytical theories and direct numerical integrations of their equations of motion. After summarizing the observational data used to determine the orbits, we discuss the results of our latest orbits obtained from a least squares fit to the data.

  18. High Temperal Resolution AOD Retrieval of Northern China in 2014 Winter Based on Geostationary Satellite Remote Sensing Data

    NASA Astrophysics Data System (ADS)

    Chen, X.; Li, Z.; Zhang, Y.; Xu, H.; Ma, Y.; Li, D.; Lv, Y.; Qie, L.; Zhang, Y.; Li, L.; Liu, Y.

    2014-12-01

    Observations from satellite can provide large region, fast and dynamic monitoring of aerosol properties. Polar Satellites provide once a day of observations at most, which is difficult to monitor aerosol temporal variabilities clearly. Only geostationary orbit satellites have the ability to provide both high temporal and spatial resolution observations. The Korea Geostationary Ocean Color Imager (GOCI) onboard COMs-1 (Communication?Ocean & Meteorological Satellite-1) mainly designed for ocean observation, but it has a good potential for land monitoring. Cross calibration between GOCI and the US Moderate Resolution Imaging Spectrometer (MODIS) can improve the land radiation characteristics of GOCI, which can expand its ability in land observation.Cross calibration results show that the simulated TOA (Top Of Atmosphere) radiance from MODIS and GOCI measured TOA radiance agrees well. The geostationary orbit satellite observing characteristics of the nearly constant view geometry and the high temporal resolution were used in aerosol retrieval algorithm. For images of two adjacent time points, the difference of TOA radiance mostly comes from the change caused by aerosol. AOD retrievals were accomplished using a Look-Up Table (LUT) strategy with assumptions of quickly varied aerosol and slowly varied surface with time. The AOD retrieval algorithm calculates AOD by minimizing the surface reflectance variations of series observations in a short period of time, e.g. several days. GOCI data from January 1, 2014 to April 1, 2014 were used to retrieve AOD, when the haze was very heavy. The monitoring of hourly AOD variations were implemented during this period and the retrieved AOD agrees well with AREONET (AErosol RObotic NETwork) ground-based measurements. The result was also compared with MODIS AOD products. In conclusion, GOCI was calibrated using MODIS data firstly in order to improve the radiation characteristics of land; then, the AOD retrieval algorithm was developed based on time series GOCI data; third, the AOD retrieval algorithm was developed to retrieve AOD synchronously.In this paper, the GOCI data are used to retrieve AOD with higher temporal resolution, which is important to atmospheric environmental monitoring.

  19. Assessment of net primary productivity over India using Indian geostationary satellite (INSAT-3A) data

    NASA Astrophysics Data System (ADS)

    Goroshi, S. K.; Singh, R. P.; Pradhan, R.; Parihar, J. S.

    2014-11-01

    Polar orbiting satellites (MODIS and SPOT) have been commonly used to measure terrestrial Net Primary Productivity (NPP) at regional/global scale. Charge Coupled Device (CCD) instrument on geostationary INSAT-3A platform provides a unique opportunity for continuous monitoring of ecosystem pattern and process study. An improved Carnegie-Ames-Stanford Approach (iCASA) model is one of the most expedient and precise ecosystem models to estimate terrestrial NPP. In this paper, an assessment of terrestrial NPP over India was carried out using the iCASA ecosystem model based on the INSAT CCD derived Normalized Difference Vegetation Index (NDVI) with multisource meteorological data for the year 2009. NPP estimated from the INSAT CCD followed the characteristic growth profile of most of the vegetation types in the country. NPP attained maximum during August and September, while minimum in April. Annual NPP for different vegetation types varied from 1104.55 gC m-2 year-1 (evergreen broadleaf forest) to 231.9 gC m-2 year-1 (grassland) with an average NPP of 590 gC m-2 year-1. We estimated 1.9 PgC of net carbon fixation over Indian landmass in 2009. Biome level comparison between INSAT derived NPP and MODIS NPP indicated a good agreement with the Willmott's index of agreement (d) ranging from 0.61 (Mixed forest) to 0.99 (Open Shrubland). Our findings are consistent with the earlier NPP studies in India and indicate that INSAT derived NPP has the capability to detect spatial and temporal variability of terrestrial NPP over a wide range of terrestrial ecosystems in India. Thus INSAT-3A data can be used as one of the potential satellite data source for accurate biome level carbon estimation in India.

  20. Monitoring biomass burning and aerosol loading and transport from a geostationary satellite perspective

    SciTech Connect

    Prins, E.M.; Menzel, W.P.

    1996-12-31

    The topic of this paper is the use of geostationary operational environmental satellites (GOES) to monitor trends in biomass burning and aerosol production and transport in South America and through the Western Hemisphere. The GOES Automated Biomass Burning Algorithm (ABBA) was developed to provide diurnal information concerning fires in South America; applications demonstrating the ability to document long-term trends in fire activity are described. Analyses of imagery collected by GOES-8 is described; six biomass burning seasons in South America revealed many examples of large-scale smoke transport extending over several million square kilometers. Four major transport regimes were identified. Case studies throughout South America, Canada, the United States, Mexico, Belize, and Guatemala have successfully demonstrated the improved capability of GOES-8 for fire and smoke monitoring in various ecosystems. Global geostationary fire monitoring will be possible with the launch of new satellites. 12 refs., 4 figs., 1 tab.

  1. Adaptive Array for Weak Interfering Signals: Geostationary Satellite Experiments. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Steadman, Karl

    1989-01-01

    The performance of an experimental adaptive array is evaluated using signals from an existing geostationary satellite interference environment. To do this, an earth station antenna was built to receive signals from various geostationary satellites. In these experiments the received signals have a frequency of approximately 4 GHz (C-band) and have a bandwidth of over 35 MHz. These signals are downconverted to a 69 MHz intermediate frequency in the experimental system. Using the downconverted signals, the performance of the experimental system for various signal scenarios is evaluated. In this situation, due to the inherent thermal noise, qualitative instead of quantitative test results are presented. It is shown that the experimental system can null up to two interfering signals well below the noise level. However, to avoid the cancellation of the desired signal, the use a steering vector is needed. Various methods to obtain an estimate of the steering vector are proposed.

  2. Attitude control system conceptual design for geostationary operational environmental satellite spacecraft series

    NASA Astrophysics Data System (ADS)

    Markley, F. L.; Bauer, F. H.; Deily, J. J.; Femiano, M. D.

    1995-03-01

    The next generation of the Geostationary Operational Environmental Satellite (GOES-N) will require extremely stringent pointing performance for improved weather prediction. These spacecraft will employ high-precision gyros and star trackers in a unique control system design concept to achieve the end-to-end pointing performance at the focal plane of the instruments. This paper presents the GOES-N attitude control system conceptual design, sensor complement trade-offs, attitude determination theory, and system performance expectations.

  3. EHL Transition Temperature Measurements on a Geostationary Operational Environmental Satellite (GOES) Filter Wheel Bearing

    NASA Technical Reports Server (NTRS)

    Jansen, Mark J.; Jones, William R., Jr.; Pepper, Stephen V.; Predmore, Roamer E.; Shogrin, Bradley A.

    2001-01-01

    The elastohydrodynamic lubrication (EHL) transition temperature was measured for a Geostationary Operational Environmental Satellite (GOES) sounder filter wheel bearing in a vacuum tribometer. Conditions included both an 89 N (20 lb.) hard and soft load, 600 rpm, temperatures between 23 C (73 F) and 85 C (185 F), and a vacuum of approximately 1.3 x 10(exp -5) Pa. Elastohydrodynamic to mixed lubrication started to occur at approximately 70 C (158 F).

  4. Workshop Report on NEXRAD-In-Space - A Geostationary Satellite Doppler Weather Radar for Hurricane Studies

    Microsoft Academic Search

    Eric A. Smith; V. Chandra Chandrasekar; Shuyi Chen; Gregory Holland; Ramesh Kakar; Simone Tanelli; Frank Marks; Gregory Tripoli

    NEXRAD-In-Space (NIS) is a mission concept to provide a geostationary satellite Doppler radar. It was developed over the last 4 years under the auspices of NASA's Earth Science Instrument Incubator Program (IIP). The NIS would provide Ka-band (35 GHz) reflectivity and line-of-sight Doppler velocity profiles over a circular Earth region of approximately 5200 km in diameter with a 12-km horizontal

  5. Low Earth orbit communications satellite

    NASA Technical Reports Server (NTRS)

    Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

    1992-01-01

    A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

  6. Nexrad-In-Space - A Geostationary Satellite Doppler Weather Radar for Hurricane Studies

    Microsoft Academic Search

    E. Im; V. Chandrasekar; S. S. Chen; G. J. Holland; R. Kakar; W. E. Lewis; F. D. Marks; E. A. Smith; S. Tanelli; G. J. Tripoli

    2007-01-01

    The Nexrad-In-Space (NIS) is a revolutionary atmospheric radar observation concept from the geostationary orbiting platform. It was developed over the last 4 years under the auspices of NASA's Earth Science Instrument Incubator Program (IIP). The NIS radar would provide Ka-band (35 GHz) reflectivity and line-of-sight Doppler velocity profiles over a circular Earth region of approximately 5200 km in diameter with

  7. High Speed Internet Access Through Unidirectional Geostationary Satellite Channels

    E-print Network

    Cohen, Reuven

    user to a direct satellite channel, at a speed 20 times faster than that of an average telephone modem a telephone modem, the speed of the received information is less than 56Kb sec, due to the modem constraints times faster than of an average telephone modem. Connectivity of a home user to the Internet is achieved

  8. On the feasibility of monitoring carbon monoxide in the lower troposphere from a constellation of Northern Hemisphere geostationary satellites. (Part 1)

    NASA Astrophysics Data System (ADS)

    Barré, Jérôme; Edwards, David; Worden, Helen; Da Silva, Arlindo; Lahoz, William

    2015-07-01

    By the end of the current decade, there are plans to deploy several geostationary Earth orbit (GEO) satellite missions for atmospheric composition over North America, East Asia and Europe with additional missions proposed. Together, these present the possibility of a constellation of geostationary platforms to achieve continuous time-resolved high-density observations over continental domains for mapping pollutant sources and variability at diurnal and local scales. In this paper, we use a novel approach to sample a very high global resolution model (GEOS-5 at 7 km horizontal resolution) to produce a dataset of synthetic carbon monoxide pollution observations representative of those potentially obtainable from a GEO satellite constellation with predicted measurement sensitivities based on current remote sensing capabilities. Part 1 of this study focuses on the production of simulated synthetic measurements for air quality OSSEs (Observing System Simulation Experiments). We simulate carbon monoxide nadir retrievals using a technique that provides realistic measurements with very low computational cost. We discuss the sampling methodology: the projection of footprints and areas of regard for geostationary geometries over each of the North America, East Asia and Europe regions; the regression method to simulate measurement sensitivity; and the measurement error simulation. A detailed analysis of the simulated observation sensitivity is performed, and limitations of the method are discussed. We also describe impacts from clouds, showing that the efficiency of an instrument making atmospheric composition measurements on a geostationary platform is dependent on the dominant weather regime over a given region and the pixel size resolution. These results demonstrate the viability of the "instrument simulator" step for an OSSE to assess the performance of a constellation of geostationary satellites for air quality measurements. We describe the OSSE results in a follow up paper (Part 2 of this study).

  9. Practical method to identify orbital anomaly as spacecraft breakup in the geostationary region

    NASA Astrophysics Data System (ADS)

    Hanada, Toshiya; Uetsuhara, Masahiko; Nakaniwa, Yoshitaka

    2012-07-01

    Identifying a spacecraft breakup is an essential issue to define the current orbital debris environment. This paper proposes a practical method to identify an orbital anomaly, which appears as a significant discontinuity in the observation data, as a spacecraft breakup. The proposed method is applicable to orbital anomalies in the geostationary region. Long-term orbital evolutions of breakup fragments may conclude that their orbital planes will converge into several corresponding regions in inertial space even if the breakup epoch is not specified. This empirical method combines the aforementioned conclusion with the search strategy developed at Kyushu University, which can identify origins of observed objects as fragments released from a specified spacecraft. This practical method starts with selecting a spacecraft that experienced an orbital anomaly, and formulates a hypothesis to generate fragments from the anomaly. Then, the search strategy is applied to predict the behavior of groups of fragments hypothetically generated. Outcome of this predictive analysis specifies effectively when, where and how we should conduct optical measurements using ground-based telescopes. Objects detected based on the outcome are supposed to be from the anomaly, so that we can confirm the anomaly as a spacecraft breakup to release the detected objects. This paper also demonstrates observation planning for a spacecraft anomaly in the geostationary region.

  10. A geostationary satellite system for mobile multimedia applications using portable, aeronautical and mobile terminals

    NASA Technical Reports Server (NTRS)

    Losquadro, G.; Luglio, M.; Vatalaro, F.

    1997-01-01

    A geostationary satellite system for mobile multimedia services via portable, aeronautical and mobile terminals was developed within the framework of the Advanced Communications Technology Service (ACTS) programs. The architecture of the system developed under the 'satellite extremely high frequency communications for multimedia mobile services (SECOMS)/ACTS broadband aeronautical terminal experiment' (ABATE) project is presented. The system will be composed of a Ka band system component, and an extremely high frequency band component. The major characteristics of the space segment, the ground control station and the portable, aeronautical and mobile user terminals are outlined.

  11. Practical method to identify orbital anomaly as spacecraft breakup in the geostationary region

    NASA Astrophysics Data System (ADS)

    Uetsuhara, Masahiko; Hanada, Toshiya

    2013-09-01

    Identifying spacecraft breakup events is an essential issue for better understanding of the current orbital debris environment. This paper proposes an observation planning approach to identify an orbital anomaly, which appears as a significant discontinuity in archived orbital history, as a spacecraft breakup. The proposed approach is applicable to orbital anomalies in the geostationary region. The proposed approach selects a spacecraft that experienced an orbital anomaly, and then predicts trajectories of possible fragments of the spacecraft at an observation epoch. This paper theoretically demonstrates that observation planning for the possible fragments can be conducted. To do this, long-term behaviors of the possible fragments are evaluated. It is concluded that intersections of their trajectories will converge into several corresponding regions in the celestial sphere even if the breakup epoch is not specified and it has uncertainty of the order of several weeks.

  12. Use of low orbital satellite communications systems for humanitarian programs

    NASA Technical Reports Server (NTRS)

    Vlasov, Vladimir N.; Gorkovoy, Vladimir

    1991-01-01

    Communication and information exchange play a decisive role in progress and social development. However, in many parts of the world the communication infrastructure is inadequate and the capacity for on-line exchange of information may not exist. This is true of underdeveloped countries, remote and relatively inaccessible regions, sites of natural disasters, and of all cases where the resources needed to create complex communication systems are limited. The creation of an inexpensive space communications system to service such areas is therefore a high priority task. In addition to a relatively low-cost space segment, an inexpensive space communications systems requires a large number of ground terminals, which must be relatively inexpensive, energy efficient (using power generated by storage batteries, or solar arrays, etc.), small in size, and must not require highly expert maintenance. The ground terminals must be portable, and readily deployable. Communications satellites in geostationary orbit at altitudes of about 36,000 km are very expensive and require complex and expensive ground stations and launch vehicles. Given current technology, it is categorically impossible to develop inexpensive satellite systems with portable ground terminals using such satellites. To solve the problem of developing an inexpensive satellite communications system that can operate with relatively small ground stations, including portable terminals, we propose to use a system with satellites in low Earth orbit, at an altitude of 900-1500 km. Because low orbital satellites are much closer to the Earth than geostationary ones and require vastly less energy expenditure by the satellite and ground terminals for transmission of messages, a system using them is relatively inexpensive. Such a system could use portable ground terminals no more complex than ordinary mobile police radios.

  13. Estimating Monthly Rainfall from Geostationary Satellite Imagery Over Amazonia, Brazil.

    NASA Astrophysics Data System (ADS)

    Cutrim, Elen Maria Camara

    The infrared regression and the grid-history satellite rainfall estimating techniques were utilized to estimate monthly rainfall in Amazonia during one month of the rainy season (March, 1980) and one month of the dry season (September, 1980). The estimates were based on 3-hourly SMS-II infrared and visible images. Three sets of coefficients for the grid history method (Marajo, Arabian Sea, and GATE) were used to estimate rainfall. The estimated rain was compared with gauge measurements over the region. The infrared regression technique overestimated by a factor of 1.5. The Marajo coefficients yielded the best estimate, especially for eastern Amazonia. In the wet month Marajo coefficients overestimated rain by 10% and in the dry month by 70%. The Arabian Sea coefficients overestimated rain and the GATE coefficients slightly underestimated rain for Amazonia. Two maps of monthly rainfall over Amazonia were constructed for March and September, 1980, combining the ground station and satellite inferred rainfall of the grid history method using the Marajo coefficients. The satellite observations and ground data were mutually compatible and were contourable on these final, composite maps. Monthly rainfall was found to be much more inhomogeneous than previously reported. In March there was a belt of high precipitation trending southwest, with higher values and sharpest gradients in the coastal area. The upper Amazon was also an area of high precipitation, both north and south of the equator. In Roraima rainfall decreased drastically to the north. In September, the area of highest precipitation was the northwestern part of Amazonas State (northern hemisphere). Rainfall elsewhere was very localized and in northeastern Amazonia varied from 0 to 150 mm. Even though the grid history method presented better results for estimating rainfall over Amazonia, the IR model could be utilized more efficiently and economically on an operational basis if the calibration were properly made with longer sampling period and better distribution of ground observations.

  14. GEO-CAPE will measure tropospheric trace gases and aerosols and coastal ocean phytoplankton, water quality, and biogeochemistry from geostationary orbit to benefit air

    E-print Network

    Meyers, Steven D.

    -CAPE instrument separately as secondary "hosted" payloads on commercial or government-owned geostationary satellites. Other government agencies have already adopted the hosted payload implementation approach because

  15. Evaluation and modeling of autonomous attitude thrust control for the Geostation Operational Environmental Satellite (GOES)-8 orbit determination

    Microsoft Academic Search

    W. Forcey; C. R. Minnie; R. L. Defazio

    1995-01-01

    The Geostationary Operational Environmental Satellite (GOES)-8 experienced a series of orbital perturbations from autonomous attitude control thrusting before perigee raising maneuvers. These perturbations influenced differential correction orbital state solutions determined by the Goddard Space Flight Center (GSFC) Goddard Trajectory Determination System (GTDS). The maneuvers induced significant variations in the converged state vector for solutions using increasingly longer tracking data spans.

  16. Characterizing tropical overshooting deep convection from joint analysis of CloudSat and geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Takahashi, Hanii; Luo, Zhengzhao Johnny

    2014-01-01

    overshooting deep convection (ODC) plays an important role in affecting the heat and constituent budgets of the upper troposphere and lower stratosphere. This study investigates the properties and behaviors of such intense deep convection using a combination of CloudSat observations and geostationary satellite data. Our study approaches the subject from two unique perspectives: first, W-band cloud profiling radar (CPR) observations from CloudSat are used, which add to our knowledge of the internal vertical structure of tropical ODC; second, each snapshot observation from CloudSat is cast into the time evolution of the convective systems through joint analysis of geostationary satellite data, which provides a lifecycle view of tropical ODC. Climatology of tropical ODC based on CloudSat data is first presented and compared with previous works. Various parameters from CloudSat observations pertaining to cloud vertical extent, convective intensity, and convective environment are analyzed. Although results broadly agree with previous studies, we show that CloudSat CPR is capable of capturing both small cloud particles and large precipitation-size particles, thus presenting a more complete depiction of the internal vertical structure of tropical ODC. Geostationary satellite observations are analyzed in conjunction with CloudSat data to identify the life stage of the convective systems (CSs) in which ODC is embedded. ODC associated with the growing, mature, and dissipating stage of the CSs represents, respectively, 66.2%, 33.4%, and 0.4% of the total population. Convective intensity of the ODC is found to be stronger during the growing stage than the mature stage.

  17. Attitude determination for three-axis stabilized geostationary meteorological satellite image navigation

    NASA Astrophysics Data System (ADS)

    Wu, Yaguang; Wang, Zhigang

    2005-11-01

    To achieve the high accuracy of attitude determination for three-axis stabilized geostationary meteorological satellite image navigation, a new approach combined gyro with star trackers is proposed, and a real-time algorithm for attitude estimation is designed. This algorithm begins with a prediction for angular rate model errors induced by gyro drifting error, and ends with the extended Kalman filtering (EKF) for attitude estimation of three-axis. A Matlab-based time domain simulation model is developed to evaluate the attitude determination performance. Simulation results demonstrate that the proposed algorithm has characteristics of high accuracy, rapid convergence and strong robustness.

  18. Precise Orbit Determination of BeiDou Navigation Satellite System

    NASA Astrophysics Data System (ADS)

    He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

    2013-04-01

    China has been developing its own independent satellite navigation system since decades. Now the COMPASS system, also known as BeiDou, is emerging and gaining more and more interest and attention in the worldwide GNSS communities. The current regional BeiDou system is ready for its operational service around the end of 2012 with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit satellites (IGSO) and four Medium Earth orbit (MEO) satellites in operation. Besides the open service with positioning accuracy of around 10m which is free to civilian users, both precise relative positioning, and precise point positioning are demonstrated as well. In order to enhance the BeiDou precise positioning service, Precise Orbit Determination (POD) which is essential of any satellite navigation system has been investigated and studied thoroughly. To further improving the orbits of different types of satellites, we study the impact of network coverage on POD data products by comparing results from tracking networks over the Chinese territory, Asian-Pacific, Asian and of global scale. Furthermore, we concentrate on the improvement of involving MEOs on the orbit quality of GEOs and IGSOs. POD with and without MEOs are undertaken and results are analyzed. Finally, integer ambiguity resolution which brings highly improvement on orbits and positions with GPS data is also carried out and its effect on POD data products is assessed and discussed in detail. Seven weeks of BeiDou data from a ground tracking network, deployed by Wuhan University is employed in this study. The test constellation includes four GEO, five IGSO and two MEO satellites in operation. The three-day solution approach is employed to enhance its strength due to the limited coverage of the tracking network and the small movement of most of the satellites. A number of tracking scenarios and processing schemas are identified and processed and overlapping orbit differences are utilized to qualify the estimated orbits and clocks. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. For the current tracking network, deploying tracking stations on the eastern side, for example in New Zealand and/or in Hawaii, will significantly reduce along-track biases of GEOs on the same side. The involvement of MEOs and ambiguity-fixing also make the orbits better but rather moderate. Key words: BeiDou, precise orbit determination (POD), tracking network, ambiguity-fixing

  19. Destination-directed, packet-switched architecture for a geostationary communications satellite network

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Shalkhauser, Mary JO; Bobinsky, Eric A.; Soni, Nitin J.; Quintana, Jorge A.; Kim, Heechul; Wager, Paul; Vanderaar, Mark

    1993-01-01

    A major goal of the Digital Systems Technology Branch at the NASA Lewis Research Center is to identify and develop critical digital components and technologies that either enable new commercial missions or significantly enhance the performance, cost efficiency, and/or reliability of existing and planned space communications systems. NASA envisions a need for low-data-rate, interactive, direct-to-the-user communications services for data, voice, facsimile, and video conferencing. The network would provide enhanced very-small-aperture terminal (VSAT) communications services and be capable of handling data rates of 64 kbps through 2.048 Mbps in 64-kbps increments. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints. The focus of current space segment developments is a flexible, high-throughput, fault-tolerant onboard information-switching processor (ISP) for a geostationary satellite communications network. The Digital Systems Technology Branch is investigating both circuit and packet architectures for the ISP. Destination-directed, packet-switched architectures for geostationary communications satellites are addressed.

  20. Thermal Physical Property-Based Fusion of Geostationary Meteorological Satellite Visible and Infrared Channel Images

    PubMed Central

    Han, Lei; Shi, Lu; Yang, Yiling; Song, Dalei

    2014-01-01

    Geostationary meteorological satellite infrared (IR) channel data contain important spectral information for meteorological research and applications, but their spatial resolution is relatively low. The objective of this study is to obtain higher-resolution IR images. One common method of increasing resolution fuses the IR data with high-resolution visible (VIS) channel data. However, most existing image fusion methods focus only on visual performance, and often fail to take into account the thermal physical properties of the IR images. As a result, spectral distortion occurs frequently. To tackle this problem, we propose a thermal physical properties-based correction method for fusing geostationary meteorological satellite IR and VIS images. In our two-step process, the high-resolution structural features of the VIS image are first extracted and incorporated into the IR image using regular multi-resolution fusion approach, such as the multiwavelet analysis. This step significantly increases the visual details in the IR image, but fake thermal information may be included. Next, the Stefan-Boltzmann Law is applied to correct the distortion, to retain or recover the thermal infrared nature of the fused image. The results of both the qualitative and quantitative evaluation demonstrate that the proposed physical correction method both improves the spatial resolution and preserves the infrared thermal properties. PMID:24919017

  1. Orbital evolution. [of large natural satellite

    NASA Technical Reports Server (NTRS)

    Burns, J. A.

    1977-01-01

    The orbital evolution of a large satellite is governed primarily by tidal interactions between the satellite and the planet it orbits. Tides raised on a planet by a satellite transfer energy and angular momentum to the satellite orbit; this changes the semimajor axes of satellite orbits, increasing the size of those orbits where the satellite mean motion is smaller than the planetary angular velocity, and decreasing those where the opposite is true. Substantial changes caused by such tides for satellites of the terrestrial planets may explain the absence of satellites about Mercury and Venus. For Jovian and Saturnian satellites, such tides probably are only important in bringing about some of the observed orbital resonances. Tides raised on satellites generally cause decreasing orbital eccentricities, indicating why close satellites always have nearly circular orbits. Different processes of orbital evolution dominate for small bodies; their effects probably are critical in positioning material in the primordial dust cloud so that satellite coagulation may occur. A qualitative description is given of the orbital results of gas drag, radiation pressure, Poynting-Robertson drag and electromagnetic forces.

  2. The Solar Dynamics Observatory After Almost Three Years in Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Pesnell, W. D.

    2012-12-01

    The Solar Dynamics Observatory (SDO) has returned science data for 2.6 years since its launch into a geostationary orbit. SDO is unique in NASA science missions in our use of a dedicated ground station that provides a 24/7 science data downlink. This continuous downlink uses the science team SOCs as the data archive and allows rapid access to the near-realtime data stream for space weather purposes. But this also means we have to run the ground station. The instruments on SDO are measuring the information needed to follow the growth and decay of the solar magnetic field. Since beginning operations watched Solar Cycle 24 grow to a below average sunspot number, with spectacular prominence eruptions and a few large flares. But we have also studied the effects of wind gusts on 18 m antennas, the wide swings in temperature in southern New Mexico, and the realities of dealing with a data system that grows by over a petabyte each year. This talk will describe some of the successes of the SDO team while also highlighting the issues that come from running a large science observatory in geostationary orbit.

  3. Remote Sensing of CO2, CH4, CO, and H2o from Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Xi, X.; Natraj, V.; Luo, M.; Zhang, Q.; Shia, R. L.; Sander, S. P.; Yung, Y. L.

    2014-12-01

    The Geostationary Carbon Process Investigation (GCPI) combines an imaging Fourier Transform Spectrometer with a geostationary Earth orbit vantage point to realize a transformational advance in monitoring carbon-bearing molecules and water vapor beyond the synoptic capabilities of Low Earth Orbit instruments such as SCIAMACHY, GOSAT and OCO-2. GCPI is designed to measure, several times every day, high-resolution spectra of reflected sunlight with a moderate signal to noise ratio in near-infrared (NIR) bands, that can then be used to obtain simultaneous retrievals of column averaged CO2, CH4, CO, and H2O. The aim of this project is to explore the potential of retrieving vertical profiles of CO2, CH4, CO, and H2O from high-resolution NIR spectra. We perform radiative transfer simulations over clear-sky conditions (as expected to be observed by GCPI) and estimate prospective performance of retrievals based on results from Bayesian error analysis and characterization. Through Observing System Simulation Experiments (OSSEs), we demonstrate the feasibility of retrieving vertical profiles of CO2 and CH4 and partial columns of CO and H2O with high accuracies and precisions. GCPI's unprecedented observations with high temporal and spatial coverage could be used to drive and constrain Earth system models, improve our understanding of the underlying carbon cycle and water cycle processes, and evaluate model forecasting capabilities.

  4. Impact of geostationary satellite water vapor channel data on weather analysis and forecasting

    NASA Technical Reports Server (NTRS)

    Velden, Christopher S.

    1995-01-01

    Preliminary results from NWP impact studies are indicating that upper-tropospheric wind information provided by tracking motions in sequences of geostationary satellite water vapor imagery can positively influence forecasts on regional scales, and possibly on global scales as well. The data are complimentary to cloud-tracked winds by providing data in cloud-free regions, as well as comparable in quality. First results from GOES-8 winds are encouraging, and further efforts and model impacts will be directed towards optimizing these data in numerical weather prediction (NWP). Assuming successful launches of GOES-J and GMS-5 satellites in 1995, high quality and resolution water vapor imagers will be available to provide nearly complete global upper-tropospheric wind coverage.

  5. Spectrum and orbit conservation as a factor in future mobile satellite system design

    NASA Technical Reports Server (NTRS)

    Bowen, Robert R.

    1990-01-01

    Access to the radio spectrum and geostationary orbit is essential to current and future mobile satellite systems. This access is difficult to obtain for current systems, and may be even more so for larger future systems. In this environment, satellite systems that minimize the amount of spectrum orbit resource required to meet a specific traffic requirement are essential. Several spectrum conservation techniques are discussed, some of which are complementary to designing the system at minimum cost. All may need to be implemented to the limits of technological feasibility if network growth is not to be constrained because of the lack of available spectrum-orbit resource.

  6. Low earth orbit satellite/terrestrial mobile service compatibility

    NASA Astrophysics Data System (ADS)

    Sheriff, R. E.; Gardiner, J. G.

    Digital cellular mobile 'second generation' systems are now gradually being introduced into service; one such example is GSM, which will provide a digital voice and data service throughout Europe. Total coverage is not expected to be achieved until the mid '90's, which has resulted in several proposals for the integration of GSM with a geostationary satellite service. Unfortunately, because terrestrial and space systems have been designed to optimize their performance for their particular environment, integration between a satellite and terrestrial system is unlikely to develop further than the satellite providing a back-up service. This lack of system compatibility is now being addressed by system designers of third generation systems. The next generation of mobile systems, referred to as FPLMTS (future public land mobile telecommunication systems) by CCIR and UMTS (universal mobile telecommunication system) in European research programs, are intended to provide inexpensive, hand-held terminals that can operate in either satellite, cellular, or cordless environments. This poses several challenges for system designers, not least in terms of the choice of multiple access technique and power requirements. Satellite mobile services have been dominated by the geostationary orbital type. Recently, however, a number of low earth orbit configurations have been proposed, for example Iridium. These systems are likely to be fully operational by the turn of the century, in time for the implementation of FPLMTS. The developments in LEO mobile satellite service technology were recognized at WARC-92 with the allocation of specific frequency bands for 'big' LEO's, as well as a frequency allocation for FPLMTS which included a specific satellite allocation. When considering integrating a space service into the terrestrial network, LEO's certainly appear to have their attractions: they can provide global coverage, the round trip delay is of the order of tens of milliseconds, and good visibility to the satellite is usually possible. This has resulted in their detailed investigation in the European COST 227 program and in the work program of the European Telecommunications Standards Institute (ETSI). This paper will consider the system implications of integrating a LEO mobile service with a terrestrial service. Results will be presented from simulation software to show how a particular orbital configuration affects the performance of the system in terms of area coverage and visibility to a terminal for various locations and minimum elevation angle. Possible network topologies are then proposed for an integrated satellite/terrestrial network.

  7. Construction of a 60 GHz Traveling Wave Tube (TWT) for intersatellite link on geostationary orbit (ISL\\/TWT)

    Microsoft Academic Search

    Gerold Lippert; Peter Malzahn

    1986-01-01

    For communication between geostationary satellites, a transmitter using a TWT amplifier with frequency 60 GHz and output power of a few watts is proposed. A focusing electrode which suppresses the edge emission and a mixed metal cathode with a low beam compression ratio are employed in the gun. For the beam tester a transmission factor of greater than 99 percent

  8. Orbit determination for ISRO satellite missions

    Microsoft Academic Search

    Ch. Sreehari Rao; S. K. Sinha

    1985-01-01

    Indian Space Research Organisation (ISRO) has been successful in using the in-house developed orbit determination and prediction software for satellite missions of Bhaskara, Rohini and APPLE. Considering the requirements of satellite missions, software packages are developed, tested and their accuracies are assessed. Orbit determination packages developed are SOIP, for low earth orbits of Bhaskara and Rohini missions, ORIGIN and ODPM,

  9. Spectrum-orbit utilization - An overview. [domestic satellite communication systems

    NASA Technical Reports Server (NTRS)

    Sawitz, P. H.

    1975-01-01

    This paper discusses the problems associated with the efficient utilization of the natural resources of frequency spectrum and geo-stationary orbital arc. The nature of these resources is explained and their quantities are estimated. The present and projected future demand for them is given, and the problem areas are identified and discussed. Special emphasis is placed on mutual interference, launch limitations, propagation effects, and operational restrictions. The technical factors bearing on these problems, such as antenna patterns, modulation methods, emission restrictions, equipment characteristics, and system requirements, are discussed in detail. Some important trade-offs are presented, and special techniques that can be used to increase spectrum-orbit utilization are described. Particular emphasis is given throughout to U.S. domestic satellite communication systems.

  10. Land Surface Temperature Estimation from the Next Generation of Geostationary Operational Environmental Satellites: GOES M–Q

    Microsoft Academic Search

    Donglian Sun; Rachel T. Pinker; Jeffery B. Basara

    2004-01-01

    The next generation of Geostationary Operational Environmental Satellites (GOES M-Q) will have only one thermal window channel instead of the current two split-window thermal channels. There is a need to evaluate the usefulness of this new configuration to retrieve parameters that presently are derived by utilizing the split- window characteristics. Two algorithms for deriving land surface temperatures (LSTs) from the

  11. Destination-directed, packet-switching architecture for 30/20-GHz FDMA/TDM geostationary communications satellite network

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Shalkhauser, Mary JO

    1992-01-01

    A destination-directed packet switching architecture for a 30/20-GHz frequency division multiple access/time division multiplexed (FDMA/TDM) geostationary satellite communications network is discussed. Critical subsystems and problem areas are identified and addressed. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints.

  12. Circuit-switch architecture for a 30/20-GHz FDMA/TDM geostationary satellite communications network

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.

    1992-01-01

    A circuit switching architecture is described for a 30/20 GHz frequency division, multiple access uplink/time division multiplexed downlink (FDMA/TDM) geostationary satellite communications network. Critical subsystems and problem areas are identified and addressed. Work was concentrated primarily on the space segment; however, the ground segment was considered concurrently to ensure cost efficiency and realistic operational constraints.

  13. Destination directed packet switch architecture for a 30/20 GHz FDMA/TDM geostationary communication satellite network

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Shalkhauser, Mary JO

    1991-01-01

    Emphasis is on a destination directed packet switching architecture for a 30/20 GHz frequency division multiplex access/time division multiplex (FDMA/TDM) geostationary satellite communication network. Critical subsystems and problem areas are identified and addressed. Efforts have concentrated heavily on the space segment; however, the ground segment was considered concurrently to ensure cost efficiency and realistic operational constraints.

  14. Next Generation Geostationary Operational Environmental Satellite (GOES-R Series): A Space Segment Overview

    NASA Technical Reports Server (NTRS)

    Krimchansky, Alexander; Machi, Dino; Cauffman, Sandra A.; Davis, Martin A.

    2004-01-01

    The next-generation National Oceanic and Atmospheric Administration (NOAA) Geostationary Operational Environmental Satellite (GOES-R series) is currently being developed by NOAA in cooperation with the National Aeronautics and Space Administration (NASA). The GOES-R series satellites represents a significant improvement in spatial, temporal, and spectral observations (several orders of magnitude) over the capabilities of the currently operational GOES-1 series and the about to be launched GOES-N series satellite. The GOES-R series will incorporate technically advanced third-generation instruments and spacecraft enhancements to meet evolving observational requirements of forecasting for the era 2012-2025. The GOES-R instrument complement being developed includes a Advanced Baseline Imager (ABI), a Hyperspectral Environmental Suite (HES), a GEO Lighting Mapper (GLM), a Solar Imaging Suite (SIS) and a Space Environment In-Situ Suite (SEISS). Also, candidates for a number of GOES-R Pre-Planned Product Improvements (P(sup 3)Is) includes a Geo microwave Sounder, a Coronograph, a Hyperspectral Imager, and a Solar Irradiance Sensor. Currently, the GOES-R Space Segment architecture is being evaluated as part of a GOES-R system end-to-end architecture study. The GOES-R notional baseline architecture is a constellation of two satellites (A-sat and B-sat) each nominally located at 75 degrees west longitude and at 135 degrees west longitude at geostationary altitude, 0 degrees inclination. The primary mission of the A-sat is to provide imaging from the ABI. The A-sat will also contain the SIS and the GLM. The primary mission of the B-sat is to provide sounding of the hemispherical disk of the earth from the HES. The B-sat also contains the SEISS. Both satellites have mesoscale capabilities for severe weather sounding or imaging. This paper overviews the GOES-R Space Segment development including satellite constellation trade-off, improvements and differences between the current and future instrument and spacecraft capabilities, and technology infusion.

  15. Satellite Constellation Orbit Evaluation (SCORE) program

    NASA Astrophysics Data System (ADS)

    Russell, L. C.

    1990-04-01

    The objective of this research was to produce a flexible, user-friendly, PC-based computer program that could assist in evaluating satellite constellations. The program would need the capability to graphically display various facets of satellite orbits and communication coverages. Both low earth-orbit and high earth-orbit satellites, would need to be evaluated. The Satellite Constellation Orbit Evaluation Program (SCORE) can be used to graphically display satellite orbits and communication coverages. Although originally developed for the Navy/Defense Advanced Research Projects Agency Satellite Laser Communications (SLC) Program, SCORE can be used to assist in the evaluation of any satellite-communication or surveillance system. A DOS floppy disk containing the executable code for SCORE is included with this report.

  16. Some accuracy aspects of satellite orbit prediction

    Microsoft Academic Search

    B. A. C. Ambrosius

    1974-01-01

    A computer program, applicable to the Astronomical Netherlands Satellite (ANS), was developed for long-term prediction of low-earth satellite orbits. The program takes into account perturbations due to the earth's gravitational potential, lunisolar attraction, and aerodynamic drag. The analytical expressions describing long-term orbital-element variations due to zonal harmonic perturbations and a method for predicting the satellite's in-orbit position over one revolution

  17. FAUST: Multi-satellite orbital dynamics software

    Microsoft Academic Search

    P. Moore; H. J. Boomkamp; S. Carnochan; R. J. Walmsley

    1999-01-01

    The orbital software FAUST with its multi-arc multi-satellite capability is illustrated for simultaneous computations of TOPEX\\/Poseidon and ERS using SLR, DORIS and PRARE tracking. The multi-arcs are bridged by single satellite crossovers with dual satellite crossovers making the connection between the different satellite orbits. The software has been used to generate a gravity field enhancement of JGM-3 utilising TOPEX\\/Poseidon and

  18. NEXRAD-In-Space: A Geostationary Orbiting Doppler Radar for Hurricane Monitoring and Studies

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Durden, Stephen L.; Tanelli, Simone; Fang, Houfei; Rahmat-Samii, Yahya

    2011-01-01

    Under NASA's Earth Science Technology Program, a novel mission concept has been developed for detailed monitoring of hurricanes, cyclones, and severe storms from a geostationary orbit: "NEXRAD in Space" (NIS). By operating in the Geostationary Earth Orbit (GEO), NIS would enable rapid-update sampling (less than or equal to 1 hour cadence) of three dimenional fields of 35 GHz (Ka-band) radar reflectivity factor (Z) and line-of-sight Doppler velocity (VD) profiles, at mesoscale horizontal resolutions (approx. 10 km) over a circular Earth region of approximately 5300 km in diameter (equivalent to much of an oceanic basin, such as the Atlantic). NIS GEO-radar concept was chosen as one of only four potential post-2020 missions for the Weather Focus area in the 2007-2016 NASA Science Mission Directorate (SMD) Science Plan. The results of the first project aiming at developing the NIS concept highlighted the enormous potential of such mission, and the technological challenges presented by it. In essence, it is because of its rapid-cadence capability that NIS science planning is focusing on hurricane monitoring and prediction. Hurricanes, or generically tropical cyclones (TCs), have always been among the most devastating natural phenomena. This has been painfully reiterated in recent years with a number of powerful TCs landfalling in North America and elsewhere. In April 2007, the first NIS Science Workshop was convened at the University of Miami to galvanize the scientific community's interest in NIS's measurement capabilities for improved TC monitoring and prediction. The general consensus of the workshop was that a GEO Doppler radar would provide a major breakthrough in regards to the observation of TCs, and, when combined with cloud-resolving numerical weather prediction (NWP) models. This paper presents brief summaries of the instrument concept, the current technology status, the anticipated impacts on hurricane monitoring and model prediction, and the future science and technology roadmap.

  19. GeoSTAR: Developing a Microwave Sounder for Geostationary Weather Satellites

    NASA Astrophysics Data System (ADS)

    Lambrigtsen, B.; Wilson, W.; Tanner, A.; Kangaslahti, P.; Gaier, T.; Dinardo, S.; Brown, S.; Piepmeier, J.; Ruf, C.

    2005-12-01

    The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new concept for a microwave sounder, intended to be deployed on NOAA's next generation of geostationary weather satellites, the GOES-R series. A ground based prototype has been developed at the Jet Propulsion Laboratory, under NASA Instrument Incubator Program (IIP) sponsorship, and is now undergoing tests and performance characterization. With the aperture synthesis approach used by GeoSTAR it is possible to achieve very high spatial resolutions even in the crucial 50-GHz temperature sounding band without having to deploy the impractically large parabolic reflector antenna that is required with the conventional approach. GeoSTAR will finally, after many years of searching for a solution, make it possible to add a microwave sounder to the GOES instrument suite - a capability that is crucial for monitoring cloudy regions and severe storms. The technology and system design required for GeoSTAR are rapidly maturing, and it is expected that a space demonstration mission can be developed before the first GOES-R launch. GeoSTAR will be ready for operational deployment 2-3 years after that. The prototype developed under IIP implements a small version of the temperature sounding component of GeoSTAR, is fully functional as a sounder and has all of the features and capabilities of an operational system with the exception of spatial resolution. It therefore represents a complete proof of concept as well as significant risk reduction for a space implementation. Further technology risk reduction, with particular focus on the 183-GHz water vapor sounding band, is also under way.

  20. Hill stability of satellite orbits

    Microsoft Academic Search

    V. V. Markellos; A. E. Roy

    1981-01-01

    Szebehely's criterion for Hill stability of satellites is derived from Hill's problem and a more exact result is obtained. Direct, Hill stable, circular satellites can exist almost twice as far from the planet as retrograde satellites. For direct satellites the new result agrees with Kuiper's empirical estimate that such satellites are stable up to a distance of half the “radius

  1. Tesseral resonance effects on satellite orbits

    Microsoft Academic Search

    G. S. Gedeon

    1969-01-01

    Resonance effects on satellite orbits due to tesseral harmonics in the potential field have been studied by many authors. Most of these studies have been restricted to nearly circular 24-hour orbits and to the deep resonance regime, where there is exact commensurability between earth rotation and orbit period. Resonance effects have also been noted, however, on eccentric synchronous and subsynchronous

  2. Coastal water quality estimation from Geostationary Ocean Color Imager (GOCI) satellite data using machine learning approaches

    NASA Astrophysics Data System (ADS)

    Im, Jungho; Ha, Sunghyun; Kim, Yong Hoon; Ha, Hokyung; Choi, Jongkuk; Kim, Miae

    2014-05-01

    It is important to monitor coastal water quality using key parameters such as chlorophyll-a concentration and suspended sediment to better manage coastal areas as well as to better understand the nature of biophysical processes in coastal seawater. Remote sensing technology has been commonly used to monitor coastal water quality due to its ability of covering vast areas at high temporal resolution. While it is relatively straightforward to estimate water quality in open ocean (i.e., Case I water) using remote sensing, coastal water quality estimation is still challenging as many factors can influence water quality, including various materials coming from inland water systems and tidal circulation. There are continued efforts to accurately estimate water quality parameters in coastal seawater from remote sensing data in a timely manner. In this study, two major water quality indicators, chlorophyll-a concentration and the amount of suspended sediment, were estimated using Geostationary Ocean Color Imager (GOCI) satellite data. GOCI, launched in June 2010, is the first geostationary ocean color observation satellite in the world. GOCI collects data hourly for 8 hours a day at 6 visible and 2 near-infrared bands at a 500 m resolution with 2,500 x 2,500 km square around Korean peninsula. Along with conventional statistical methods (i.e., various linear and non-linear regression), three machine learning approaches such as random forest, Cubist, and support vector regression were evaluated for coastal water quality estimation. In situ measurements (63 samples; including location, two water quality parameters, and the spectra of surface water using a hand-held spectroradiometer) collected during four days between 2011 and 2012 were used as reference data. Due to the small sample size, leave-one-out cross validation was used to assess the performance of the water quality estimation models. Atmospherically corrected radiance data and selected band-ratioed images were used as predictor variables. Results show that support vector regression outperformed the other two machine learning approaches as well as conventional statistical models, yielding calibration R2 of 0.9 and cross validation RMSE of 1.7 mg/m3 for chlorophyll-a concentration, and calibration R2 of 0.97 and cross validation RMSE of 11.4 g/m3 for suspended sediment. Relative importance of the predictor variables was examined and the spatiotemporal patterns of the water quality parameter distribution were analyzed along with tidal information.

  3. First results of measurements of extreme ultraviolet radiation onboard a geostationary satellite "ELECTRO-L"

    NASA Astrophysics Data System (ADS)

    Nusinov, Anatoliy; Kazachevskaya, Tamara; Gonjukh, David

    Measurements of the intensity of EUV emission in the hydrogen Lyman-alpha line were conducted by a broadband photometer VUSS-E onboard geostationary Hydrometeorological satellite "Electro" since March 2011. The solar hydrogen Lyman-alpha line (lambda = 121.6 nm) was monitored. The photomultiplier with LiF window used as a detector insensitive to visible light. Long-wavelength limit of the spectral band sensitivity of the instrument is about 200 nm, so the signal of the device is defined as the flux of solar radiation in the region of 123-200 nm. Its exclusion was carried out by calculation. Since the satellite "Electro" designed for remote sensing of the Earth, its line of sight focused on Earth. Alignment of instrument in the Sun direction was achieved by installing it on the solar panel, periodically moved in the solar direction. Correction of instrument readings, reduced due to the deviation of its axis from the Sun direction, carried out by calculation. Measurements were carried out every second. The first results of the measurements are presented. The difference in absolute calibration Electro-L/VUSS-E is within 5% of corresponding values for measurements TIMED satellite in those days, that is in agreement with laboratory calibrations. It is useful to measure the temperature of the instrument, as its variation on a small interval of time makes change the value of the output signal about 1-2 %. During first year of operation, the sensitivity of the apparatus remained within ± 2% of measured value, significant degradation of sensitivity was not observed. Over time of observation there have been several large flares of X class. The increase of the signal in the ultraviolet range does not exceed a few percent during these flares.

  4. Use of geostationary meteorological satellite images in convective rain estimation for flash-flood forecasting

    NASA Astrophysics Data System (ADS)

    Wardah, T.; Abu Bakar, S. H.; Bardossy, A.; Maznorizan, M.

    2008-07-01

    SummaryFrequent flash-floods causing immense devastation in the Klang River Basin of Malaysia necessitate an improvement in the real-time forecasting systems being used. The use of meteorological satellite images in estimating rainfall has become an attractive option for improving the performance of flood forecasting-and-warning systems. In this study, a rainfall estimation algorithm using the infrared (IR) information from the Geostationary Meteorological Satellite-5 (GMS-5) is developed for potential input in a flood forecasting system. Data from the records of GMS-5 IR images have been retrieved for selected convective cells to be trained with the radar rain rate in a back-propagation neural network. The selected data as inputs to the neural network, are five parameters having a significant correlation with the radar rain rate: namely, the cloud-top brightness-temperature of the pixel of interest, the mean and the standard deviation of the temperatures of the surrounding five by five pixels, the rate of temperature change, and the sobel operator that indicates the temperature gradient. In addition, three numerical weather prediction (NWP) products, namely the precipitable water content, relative humidity, and vertical wind, are also included as inputs. The algorithm is applied for the areal rainfall estimation in the upper Klang River Basin and compared with another technique that uses power-law regression between the cloud-top brightness-temperature and radar rain rate. Results from both techniques are validated against previously recorded Thiessen areal-averaged rainfall values with coefficient correlation values of 0.77 and 0.91 for the power-law regression and the artificial neural network (ANN) technique, respectively. An extra lead time of around 2 h is gained when the satellite-based ANN rainfall estimation is coupled with a rainfall-runoff model to forecast a flash-flood event in the upper Klang River Basin.

  5. Rock-Around Orbits

    E-print Network

    Bourgeois, Scott K.

    2010-07-14

    with larger orbits far above the Earth's surface, e.g. a Geostationary Orbit. Camera systems mounted on satellites can provide an eff ective way to observe these objects. Using a satellite with a speci c orbit relative to the RSO's orbit, one can passively...

  6. Long-term statistics of laser beam propagation in an optical ground-to-geostationary satellite communications link

    Microsoft Academic Search

    Morio Toyoshima; Shiro Yamakawa; Toshihiko Yamawaki; Katsuyoshi Arai; Marcos Reyes García-Talavera; Angel Alonso; Zoran Sodnik; Benoit Demelenne

    2005-01-01

    A ground-to-space laser communications experiment was conducted to verify the optical interfaces between a laser communications terminal in an optical ground station and an optical payload onboard a geostationary satellite 38 000 km away. The end-to-end optical characteristics such as intensity, sensitivity, wavelength, polarization, and the modulation scheme of optical signals as well as acquisition sequences of the terminals were

  7. Advanced Communications Technology Satellite (ACTS) Used for Inclined Orbit Operations

    NASA Technical Reports Server (NTRS)

    Bauer, Robert A.

    2000-01-01

    The Advanced Communications Technology Satellite (ACTS) is operated by the NASA Glenn Research Center at Lewis Field 24 hours a day, 7 days a week. ACTS, which was launched in September 1993, is in its 7th year of operations, far exceeding the system s planned 2 years of operations and 4 years of designed mission life. After 5 successful years of operating as a geostationary satellite, the spacecraft s North-South stationkeeping was discontinued in August 1998. The system is now operating in an inclined orbit that increases at a rate of 0.8 /yr. With only scarce fuel remaining, operating in this mode extends the usage of the still totally functional payload. Although tracking systems are now needed on the experimenter Earth stations, experiment operations have continued with very little disruption. This is the only known geosynchronous Ka-band (30/20 GHz) spot-beam satellite operating in an inclined orbit. The project began its transition from geostationary operations to inclined operations in August 1998. This did not interrupt operations and was transparent to the experimenters on the system. For the space segment, new daily procedures were implemented to maintain the pointing of the system s narrow 0.3 spot beams while the spacecraft drifts in the North-South direction. For the ground segment, modifications were designed, developed, and fielded for the three classes of experimenter Earth stations. With the next generation of commercial satellite systems still being developed, ACTS remains the only operational testbed for Ka-band geosynchronous satellite communications over the Western hemisphere. Since inclined orbit operations began, the ACTS experiments program has supported 43 investigations by industry, Government, and academic organizations, as well as four demonstrations. The project s goals for inclined-orbit operations now reflect a narrower focus in the types of experiments that will be done. In these days of "faster, better, cheaper," NASA is seeking to gain greater relevance to the agency s mission from these experiments. One area that is of much interest both to NASA and the commercial world is the investigation of protocol issues related to the interoperability of satellites with terrestrial networks, such as Transmission Control Protocol/Internet Protocol (TCP/IP) and Asynchronous Transfer Mode (ATM) over wideband satellites. Other experiment areas of interest are supporting the U.S. Government and NASA as they begin using commercial space assets to meet their communications needs, evaluating issues related to operating a spot-beam satellite in inclined orbit, and evaluating new Ka-band hardware that requires a satellite link. ACTS is now in its last year of operations. Operations are planned through June 2000, when after 81 months of operations, this very successful spacecraft will be superorbited and made inert.

  8. An Analytical Satellite Orbit Predictor (ASOP)

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The documentation and user's guide are presented for the analytical satellite orbit predictor computer program which is intended to be used for computation of near-earth orbits including those of the shuttle orbiter and its payloads. The Poincare-Similar elements used make it possible to compute near-earth orbits to within an accuracy of a few meters. Recursive equations are used instead of complicated formulas. Execution time is on the order of a few milliseconds.

  9. Land Surface Temperature Estimation from the Next Generation of Geostationary Operational Environmental Satellites: GOES M Q.

    NASA Astrophysics Data System (ADS)

    Sun, Donglian; Pinker, Rachel T.; Basara, Jeffery B.

    2004-02-01

    The next generation of Geostationary Operational Environmental Satellites (GOES M Q) will have only one thermal window channel instead of the current two split-window thermal channels. There is a need to evaluate the usefulness of this new configuration to retrieve parameters that presently are derived by utilizing the split-window characteristics. Two algorithms for deriving land surface temperatures (LSTs) from the GOES M Q series have been developed and will be presented here. Both algorithms are based on radiative transfer theory; one uses ancillary total precipitable water (TPW) data, and the other is a two-channel (3.9 and 11.0 ?m) algorithm that aims to improve atmospheric correction by utilizing the middle infrared (MIR) channel. The proposed algorithms are compared with a well-known generalized split-window algorithm. It is found that by adding TPW to the 11.0-?m channel, similar results to those from the generalized split-window algorithm are attained, and the combination of 3.9 and 11.0 ?m yields further improvement. GOES M Q retrievals (simulated with GOES-8 observations), when evaluated against skin temperature observations from the Oklahoma Mesonet, show that with the proposed two-channel algorithm, LST can be determined at an rms accuracy of about 2 K. The proposed algorithms are also applicable for the derivation of sea surface temperatures (SSTs) for which less restrictive assumptions on surface emissivity apply.

  10. Satellite Proving Ground for the GOES-R Geostationary Lightning Mapper (GLM)

    NASA Technical Reports Server (NTRS)

    Goodman, Steven J.; Gurka, James; Bruning, E. C.; Blakeslee, J. R.; Rabin, Robert; Buechler, D.

    2009-01-01

    The key mission of the Satellite Proving Ground is to demonstrate new satellite observing data, products and capabilities in the operational environment to be ready on Day 1 to use the GOES-R suite of measurements. Algorithms, tools, and techniques must be tested, validated, and assessed by end users for their utility before they are finalized and incorporated into forecast operations. The GOES-R Proving Ground for the Geostationary Lightning Mapper (GLM) focuses on evaluating how the infusion of the new technology, algorithms, decision aids, or tailored products integrate with other available tools (weather radar and ground strike networks; nowcasting systems, mesoscale analysis, and numerical weather prediction models) in the hands of the forecaster responsible for issuing forecasts and warning products. Additionally, the testing concept fosters operation and development staff interactions which will improve training materials and support documentation development. Real-time proxy total lightning data from regional VHF lightning mapping arrays (LMA) in Northern Alabama, Central Oklahoma, Cape Canaveral Florida, and the Washington, DC Greater Metropolitan Area are the cornerstone for the GLM Proving Ground. The proxy data will simulate the 8 km Event, Group and Flash data that will be generated by GLM. Tailored products such as total flash density at 1-2 minute intervals will be provided for display in AWIPS-2 to select NWS forecast offices and national centers such as the Storm Prediction Center. Additional temporal / spatial combinations are being investigated in coordination with operational needs and case-study proxy data and prototype visualizations may also be generated from the NASA heritage Lightning Imaging Sensor and Optical Transient Detector data. End users will provide feedback on the utility of products in their operational environment, identify use cases and spatial/temporal scales of interest, and provide feedback to the developers for adjusted or new products.

  11. Future Plan and Recent Activities for the Japanese Follow-on Geostationary Meteorological Satellite Himawari-8/9

    NASA Astrophysics Data System (ADS)

    Kurino, T.

    2012-12-01

    In 1977, Japan launched the first geostationary meteorological satellite " Himawari-1 (GMS-1)" onto the geo-synchronous orbit at 140°E mainly to cover the western Pacific and the east part of Asia as part of a space segment of the Global Observation System (GOS) of the WMO World Weather Watch (WWW) programme up to the present. JMA plans to launch Himawari-8 in summer 2014 and commence its operation in 2015, when Himawari-7 (MTSAT-2) is scheduled to complete its period of operation. The Agency also plans to launch Himawari-9 in 2016. Himawari-8 and -9 carry Advanced Himawari Imager (AHI) units comparable to the Advanced Baseline Imager (ABI) on board GOES-R with the following functions: - Multi-channel capacity (16 channels in visible and infrared bands) - High spatial resolution (0.5 - 1.0 km for visible and 1.0 - 2.0 km for infrared) - High temporal resolution (within 10 minutes for full disk) - Rapid scanning with flexible area selection and scheduling The follow-on satellites will offer high observation potential, which will enable users to analyze cloud properties and extract other meteorological parameters. To make the most of these functions as well as to provide users with effective information from the start of Himawari-8's operation, JMA has set up an environment for the development of new products from the follow-on satellites in collaboration with its Meteorological Satellite Center (MSC) and other internal related divisions in JMA. The Agency also plans to start the development of related products, and is interested in pursuing scientific and prototyping activities in collaboration with Coordination Group for Meteorological Satellites (CGMS) members. This is particularly the case with EUMETSAT and NOAA/NESDIS, which already operate or are preparing to use a new generation of multi-channel imaging instruments (e.g. MSG/MTG, GOES-R). To support these developments, Himawari-8/9 simulated images are generated in two ways - one involving the accumulation of high-spectral-channel observations from hyper sounders such as AIRS and IASI, and the other using radiative transfer computation based on the provisional response functions of Himawari-8/9. To deliver the more accurate satellite observations, it is vital that satellite instrument calibration is of the highest quality and that a capability exists to intercalibrate the satellite sensors. JMA has been participating in the Global Space-Based Inter-Calibration System (GSICS) since the system's establishment in 2007. The primary goal of GSICS is to achieve operational inter-calibration of the space component of the WWW's GOS and Global Earth Observing System of Systems (GEOSS) that addresses the climate, weather forecasting and other environmental needs of WMO Members.

  12. Observations in the thermal IR and visible of a retired satellite in the graveyard orbit, and comparisons to active satellites in GEO

    NASA Astrophysics Data System (ADS)

    Skinner, Mark A.; Russell, Ray W.; Kelecy, Tom; Gregory, Steve; Rudy, Richard J.; Kim, Daryl L.; Crawford, Kirk

    2014-12-01

    There exists a population of defunct satellites in the geo-stationary arc that potentially pose a hazard to current and future operational satellites. These drifting, non-station-kept objects have a variety of ages and sizes, and many are trapped in libration orbits around the Earth's two gravitational potential wells (the non-spherical nature of the Earth gives rise to two geo-potential wells or "stable points" that affect objects in geostationary and geosynchronous orbits), whereas others were boosted to higher altitudes into so-called "graveyard" orbits. We have observed several of the approximately 49 objects in libration orbits about the Western stable point (R. Choc, T. Flohrer, and B. Bastida, "Classification of Geosynchronous Objects," Issue 13, ESA/ESOC, February 2011), as well as objects in graveyard orbits. We have carried out an observational campaign utilizing The Aerospace Corporation's 3-13 ?m Broadband Array Spectrograph System (BASS), as well as with several optical sensors to collect data on a representative sample of these objects at a variety of solar phase angles. Here we report on recent BASS observations of a retired satellite in the "graveyard" orbit, and compare them with data we had collected over six years ago, while the satellite was still active. Data are also presented on similar satellites that are still active. We describe our methods, the data collected, our results, and our future plans.

  13. Orbit Mechanics About Planetary Satellites

    Microsoft Academic Search

    M. E. Paskowitzyand; D. J. Scheeresz

    This paper explores orbit mechanics in the Hill 3-body problem, concentrating on spacecraft motion about Jupiter's moon Europa. Orbits about Europa are of particular interest due to the proposed NASA Jupiter Icy Moons Orbiter Mission (JIMO). Using an averaging approach with first order corrections, we develop an approximate theory of motion valid over a wide range of initial conditions. Using

  14. The Orbits of the Regular Jovian Satellites

    NASA Astrophysics Data System (ADS)

    Jacobson, R.

    2014-04-01

    At the conclusion of the Galileo Mission we produced ephemerides for the Galilean and four inner Jovian satellites, Amalthea, Thebe, Adrastea, and Metis [1]. The satellite orbits were determined by fitting a data set that included Earthbased astrometry through 2001 and data acquired by the Pioneer, Voyager, Ulysses, Cassini, and Galileo spacecraft. The spacecraft tracking data provided additional information on the Jovian system gravity parameters. In preparation for the Juno mission currently enroute to Jupiter, we have been developing new ephemerides from updated satellite orbits. As before, the orbits are determined through a comprehensive data fit which also redetermines the gravity parameters and spacecraft trajectories to be consistent with the revised satellite orbits. Our standard model for the orbits, both satellite and spacecraft, is a numerical integration of their equations of motion. We include the gravitational effects of the point mass mutual interactions of Jupiter, the Galilean satellites, and Amalthea (Thebe, Adrastea, and Metis are assumed to be massless), the effects of an oblate Jupiter, and perturbations from the Sun and planets. For our new orbits we also take into account the effects of tides raised on Jupiter by the satellites. Lainey et al. [4] have pointed out the importance of the tidal accelerations. The spacecraft are also affected by nongravitational forces, e.g., solar radiation pressure, trajectory correction maneuvers. These forces are discussed by several authors [2, 3, 5]. Our current data set is an expansion of that used previously. We have extended the Galilean satellite Earthbased astrometry back to 1891 and forward to 2013 and the inner satellite astrometry back to 1892 and forward to 2002. We added the Galilean satellite mutual events from 2003 and 2009, the Galilean satellite eclipse timings from 1878 to 2013, and the Earthbased radar ranges to Ganymede and Callisto measured in 1992. We also augmented our spacecraft data set with imaging acquired by the New Horizons spacecraft when it flew through the Jovian system in February 2007. In this paper we present the results of our latest determination of the satellite orbits and associated gravity parameters. We compare the orbits and gravity parameters to those that we found previously and our tidal parameters to those of Lainey et al.. We comment on possible future modifications and enhancements before our ephemeris delivery to the Juno Project for orbital operations.

  15. Experimental Study on the Precise Orbit Determination of the BeiDou Navigation Satellite System

    PubMed Central

    He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

    2013-01-01

    The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Besides the standard positioning service with positioning accuracy of about 10 m, both precise relative positioning and precise point positioning are already demonstrated. As is well known, precise orbit and clock determination is essential in enhancing precise positioning services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS) network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better. PMID:23529116

  16. A method for diagnosing surface parameters using geostationary satellite imagery and a boundary-layer model. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Polansky, A. C.

    1982-01-01

    A method for diagnosing surface parameters on a regional scale via geosynchronous satellite imagery is presented. Moisture availability, thermal inertia, atmospheric heat flux, and total evaporation are determined from three infrared images obtained from the Geostationary Operational Environmental Satellite (GOES). Three GOES images (early morning, midafternoon, and night) are obtained from computer tape. Two temperature-difference images are then created. The boundary-layer model is run, and its output is inverted via cubic regression equations. The satellite imagery is efficiently converted into output-variable fields. All computations are executed on a PDP 11/34 minicomputer. Output fields can be produced within one hour of the availability of aligned satellite subimages of a target area.

  17. Predicting the Orbits of Satellites with a TI-85 Calculator.

    ERIC Educational Resources Information Center

    Papay, Kate; And Others

    1996-01-01

    Describes a project that predicts the orbits of satellites using a TI-85 calculator. Enables students to achieve a richer understanding of longitude, latitude, time zones, orbital mechanics of satellites, and the terms associated with satellite tracking. (JRH)

  18. NATIONAL POLAR-ORBITTING OPERATIONAL ENVIRONMENTAL SATELLITE SYSTEM (NPOESS)

    E-print Network

    NATIONAL POLAR-ORBITTING OPERATIONAL ENVIRONMENTAL SATELLITE SYSTEM (NPOESS) INTEGRATED PROGRAM) National Polar-orbiting Operational Environmental Satellite System (NPOESS) Integrated Program Office (IPO and Atmospheric Administration (NOAA) National Environmental Satellite, Data, and Information Services (NESDIS

  19. Verifying the Accuracy of Geostationary Weather Satellite Image Navigation and Registration

    NASA Astrophysics Data System (ADS)

    Carr, J. L.; Herndon, D.; Reehl, S.

    2012-12-01

    The next generation GOES-R geostationary weather satellites will provide imagery products with improved spatial and temporal resolutions and with more spectral bands than previous systems. Image Navigation and Registration (INR), which enables users to accurately pinpoint severe weather and stabilizes movie loops, will also improve. As INR performance improves, so must the technology for measuring INR performance. We describe our Product Monitoring (PM) system being deployed with the GOES-R ground system. It automatically measures INR performance using landmarks that are positioned with respect to a digital map created from the Shuttle Radar Topographic Mission (SRTM). Performance testing with Meteosat Second Generation (MSG) proxy data is part of the verification of the PM system, which is the main focus of this paper. A legacy system ironically called the Replacement Product Monitor (RPM) is in operational use on the GOES-NOP program. It is generally assumed that this system is capable of measuring the absolute position of landmark features relative to their mapped locations with an accuracy of about 0.5 pixels. This is plausible given that observed INR navigation error is about 1 pixel at the finest GOES-NOP resolution. However, a few landmark sites are observed to have biases possibly related to mapping error in the legacy digital map (not SRTM). Because the GOES-R system has finer spatial resolution than the GOES-NOP system and more stringent INR requirements, errors at the GOES-NOP pixel level are quite important. Our verification work with the GOES-R PM seeks to systematically characterize the measurement errors in a controlled test environment to demonstrate its suitability for a GOES-R mission with finer spatial resolution and more stringent INR requirements in comparison with GOES-NOP.

  20. PREDICT: Satellite tracking and orbital prediction

    NASA Astrophysics Data System (ADS)

    Magliacane, John A.

    2011-12-01

    PREDICT is an open-source, multi-user satellite tracking and orbital prediction program written under the Linux operating system. PREDICT provides real-time satellite tracking and orbital prediction information to users and client applications through: the system console the command line a network socket the generation of audio speechData such as a spacecraft's sub-satellite point, azimuth and elevation headings, Doppler shift, path loss, slant range, orbital altitude, orbital velocity, footprint diameter, orbital phase (mean anomaly), squint angle, eclipse depth, the time and date of the next AOS (or LOS of the current pass), orbit number, and sunlight and visibility information are provided on a real-time basis. PREDICT can also track (or predict the position of) the Sun and Moon. PREDICT has the ability to control AZ/EL antenna rotators to maintain accurate orientation in the direction of communication satellites. As an aid in locating and tracking satellites through optical means, PREDICT can articulate tracking coordinates and visibility information as plain speech.

  1. Orbit determination in satellite geodesy

    Microsoft Academic Search

    G. Beutler; T. Schildknecht; U. Hugentobler; W. Gurtner

    2003-01-01

    For centuries orbit determination in Celestial Mechanics was a synonym for the determination of six so-called Keplerian elements of the orbit of a minor planet or a comet based on a short series of (three or more) astrometric places observed from one or more observatories on the Earth's surface. With the advent of the space age the problem changed considerably

  2. Online Visualization and Analysis of Merged Global Geostationary Satellite Infrared Dataset

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Ostrenga, D.; Leptoukh, G.; Mehta, A.

    2008-12-01

    The NASA Goddard Earth Sciences Data Information Services Center (GES DISC) is home of Tropical Rainfall Measuring Mission (TRMM) data archive. The global merged IR product, also known as, the NCEP/CPC 4-km Global (60°N - 60°S) IR Dataset, is one of TRMM ancillary datasets. They are globally-merged (60°N-60°S) pixel-resolution (4 km) IR brightness temperature data (equivalent blackbody temperatures), merged from all available geostationary satellites (GOES-8/10, METEOSAT-7/5 & GMS). The availability of data from METEOSAT-5, which is located at 63E at the present time, yields a unique opportunity for total global (60°N-60°S) coverage. The GES DISC has collected over 8 years of the data beginning from February of 2000. This high temporal resolution dataset can not only provide additional background information to TRMM and other satellite missions, but also allow observing a wide range of meteorological phenomena from space, such as, mesoscale convection system, tropical cyclones, hurricanes, etc. The dataset can also be used to verify model simulations. Despite that the data can be downloaded via ftp, however, its large volume poses a challenge for many users. A single file occupies about 70 MB disk space and there is a total of ~73,000 files (~4.5 TB) for the past 8 years. Because there is a lack of data subsetting service, one has to download the entire file, which could be time consuming and require a lot of disk space. In order to facilitate data access, we have developed a web prototype, the Global Image ViewER (GIVER), to allow users to conduct online visualization and analysis of this dataset. With a web browser and few mouse clicks, users can have a full access to over 8 year and over 4.5 TB data and generate black and white IR imagery and animation without downloading any software and data. Basic functions include selection of area of interest, single imagery or animation, a time skip capability for different temporal resolution and image size. Users can save an animation as a file (animated gif) and import it in other presentation software, such as, Microsoft PowerPoint. These capabilities along with examples will be presented in this poster. The prototype will be integrated into GIOVANNI and existing GIOVANNI capabilities, such as, data download, Google Earth KMZ, etc. will be available. Users will also be able to access other data products in the GIOVANNI family.

  3. Online Visualization and Analysis of Merged Global Geostationary Satellite Infrared Dataset

    NASA Technical Reports Server (NTRS)

    Liu, Zhong; Ostrenga, D.; Leptoukh, G.; Mehta, A.

    2008-01-01

    The NASA Goddard Earth Sciences Data Information Services Center (GES DISC) is home of Tropical Rainfall Measuring Mission (TRMM) data archive. The global merged IR product also known as the NCEP/CPC 4-km Global (60 degrees N - 60 degrees S) IR Dataset, is one of TRMM ancillary datasets. They are globally merged (60 degrees N - 60 degrees S) pixel-resolution (4 km) IR brightness temperature data (equivalent blackbody temperatures), merged from all available geostationary satellites (GOES-8/10, METEOSAT-7/5 and GMS). The availability of data from METEOSAT-5, which is located at 63E at the present time, yields a unique opportunity for total global (60 degrees N- 60 degrees S) coverage. The GES DISC has collected over 8 years of the data beginning from February of 2000. This high temporal resolution dataset can not only provide additional background information to TRMM and other satellite missions, but also allow observing a wide range of meteorological phenomena from space, such as, mesoscale convection systems, tropical cyclones, hurricanes, etc. The dataset can also be used to verify model simulations. Despite that the data can be downloaded via ftp, however, its large volume poses a challenge for many users. A single file occupies about 70 MB disk space and there is a total of approximately 73,000 files (approximately 4.5 TB) for the past 8 years. In order to facilitate data access, we have developed a web prototype to allow users to conduct online visualization and analysis of this dataset. With a web browser and few mouse clicks, users can have a full access to over 8 year and over 4.5 TB data and generate black and white IR imagery and animation without downloading any software and data. In short, you can make your own images! Basic functions include selection of area of interest, single imagery or animation, a time skip capability for different temporal resolution and image size. Users can save an animation as a file (animated gif) and import it in other presentation software, such as, Microsoft PowerPoint. The prototype will be integrated into GIOVANNI and existing GIOVANNI capabilities, such as, data download, Google Earth KMZ, etc will be available. Users will also be able to access other data products in the GIOVANNI family.

  4. Use of geostationary satellite imagery in optical and thermal bands for the estimation of soil moisture status and land evapotranspiration

    NASA Astrophysics Data System (ADS)

    Ghilain, N.; Arboleda, A.; Gellens-Meulenberghs, F.

    2009-04-01

    For water and agricultural management, there is an increasing demand to monitor the soil water status and the land evapotranspiration. In the framework of the LSA-SAF project (http://landsaf.meteo.pt), we are developing an energy balance model forced by remote sensing products, i.e. radiation components and vegetation parameters, to monitor in quasi real-time the evapotranspiration rate over land (Gellens-Meulenberghs et al, 2007; Ghilain et al, 2008). The model is applied over the full MSG disk, i.e. including Europe and Africa. Meteorological forcing, as well as the soil moisture status, is provided by the forecasts of the ECMWF model. Since soil moisture is computed by a forecast model not dedicated to the monitoring of the soil water status, inadequate soil moisture input can occur, and can cause large effects on evapotranspiration rates, especially over semi-arid or arid regions. In these regions, a remotely sensed-based method for the soil moisture retrieval can therefore be preferable, to avoid too strong dependency in ECMWF model estimates. Among different strategies, remote sensing offers the advantage of monitoring large areas. Empirical methods of soil moisture assessment exist using remotely sensed derived variables either from the microwave bands or from the thermal bands. Mainly polar orbiters are used for this purpose, and little attention has been paid to the new possibilities offered by geosynchronous satellites. In this contribution, images of the SEVIRI instrument on board of MSG geosynchronous satellites are used. Dedicated operational algorithms were developed for the LSA-SAF project and now deliver images of land surface temperature (LST) every 15-minutes (Trigo et al, 2008) and vegetations indices (leaf area index, LAI; fraction of vegetation cover, FVC; fraction of absorbed photosynthetically active radiation, FAPAR) every day (Garcia-Haro et al, 2005) over Africa and Europe. One advantage of using products derived from geostationary satellites is the close monitoring of the diurnal variation of the land surface temperature. This feature reinforced the statistical strength of empirical methods. An empirical method linking land surface morning heating rates and the fraction of the vegetation cover, also known as a ‘Triangle method' (Gillies et al, 1997) is examined. This method is expected to provide an estimation of a root-zone soil moisture index. The sensitivity of the method to wind speed, soil type, vegetation type and climatic region is explored. Moreover, the impact of the uncertainty of LST and FVC on the resulting soil moisture estimates is assessed. A first impact study of using remotely sensed soil moisture index in the energy balance model is shown and its potential benefits for operational monitoring of evapotranspiration are outlined. References García-Haro, F.J., F. Camacho-de Coca, J. Meliá, B. Martínez (2005) Operational derivation of vegetation products in the framework of the LSA SAF project. Proceedings of the EUMETSAT Meteorological Satellite Conference Dubrovnik (Croatia) 19-23 Septembre. Gellens-Meulenberghs, F., Arboleda, A., Ghilain, N. (2007) Towards a continuous monitoring of evapotranspiration based on MSG data. Proceedings of the symposium on Remote Sensing for Environmental Monitoring and Change Detection. IAHS series. IUGG, Perugia, Italy, July 2007, 7 pp. Ghilain, N., Arboleda, A. and Gellens-Meulenberghs, F., (2008) Improvement of a surface energy balance model by the use of MSG-SEVIRI derived vegetation parameters. Proceedings of the 2008 EUMETSAT meteorological satellite data user's conference, Darmstadt, Germany, 8th-12th September, 7 pp. Gillies R.R., Carlson T.N., Cui J., Kustas W.P. and Humes K. (1997), Verification of the triangle method for obtaining surface soil water content and energy fluxes from remote measurements of Normalized Difference Vegetation Index (NDVI) and surface radiant temperature, International Journal of Remote Sensing, 18, pp. 3145-3166. Trigo, I.F., Monteiro I.T., Olesen F. and Kabsch E. (2008) An assessment of remotely sensed land

  5. Exposure estimates for repair satellites at geosynchronous orbit

    NASA Astrophysics Data System (ADS)

    Badavi, Francis F.

    2013-02-01

    Communications and weather satellites in geosynchronous (GEO, altitude: 35,793 km.) and geostationary orbits (GSO) are revolutionizing our ability to almost instantly communicate with each other, capture high resolution global imagery for weather forecasting and obtain a multitude of other geophysical data for environmental protection purposes. The rapid increase in the number of satellites at GEO is partly due to the exponential expansion of the internet, its commercial potential and the need to deliver a large amount of digital information in near real time. With the large number of satellites operating at GEO and particularly at GSO, there is a need to think of viable approaches to retrieve, rejuvenate and perhaps repair these satellites. The first step in this process is a detailed understanding of the ionizing radiation environment at GEO. Currently, the most widely used trapped particle radiation environment definition near Earth is based on the NASA's static AP8/AE8 models which define the trapped proton and electron intensities. These models are based on a large number of satellite measurements carried out in the 1960s and 1970s. In this paper, the AP8/AE8 models as well as a heavy ion galactic cosmic ray (GCR) model are used to define the radiation environments for protons, electrons and heavy ions at low Earth orbit (LEO), medium Earth orbit (MEO) and GEO. LEO and MEO dosimetric calculations are included in the analysis since any launch platform capable of delivering a payload to GEO will accumulate exposure during its transit through LEO and MEO. The computational approach (particle transport) taken in this paper is to use the static LEO, MEO, GEO and geomagnetically attenuated GCR environments as input to the NASA Langley Research Center (LaRC) developed deterministic particle transport codes high charge and energy transport (HZETRN) and coupled electron photon transport (CEPTRN). This is done through exposure prediction within a spherical shell, a legacy Apollo era command service module (CSM) configuration, and a large modular structure represented by a specific configuration of the international Space Station (ISS-11A, circa 2005). Based on the results of the simulations, conclusions are drawn on the exposure levels accumulated by these geometries throughout a mission to GEO.

  6. Parallel computation of satellite orbit acceleration

    NASA Astrophysics Data System (ADS)

    Fukushima, Toshio

    2012-12-01

    We present a formulation of parallel computation of the satellite orbit acceleration due to non-spherical gravitational field. The key techniques are the vector computation of associated Legendre functions and the do-loop folding. These are easily implemented by a slight modification of existing programs and by embedding a few OpenMP directives. The formulation significantly speeds up the orbit integrations of low-altitude satellites. For example, that of GRACE under the influence of EGM2008, a 2190×2159 geopotential model runs around 4 times faster than the serial computation if conducted at a PC with a quad-core 8-thread processor.

  7. Automated testing of low-orbiting satellites

    NASA Technical Reports Server (NTRS)

    Barbiere, D.; Wellspeak, G. J.; Konig, J. P.

    1985-01-01

    This paper describes the hardware, software, and test procedures implemented at a ground station for the automated testing of a polar-orbiting satellite in a low orbit. The satellite passes during the testing were characterized by short visibility times of no more than 18 min and by high rates of change of the link parameters as seen by the ground station. The advantages of automated testing became apparent for these dynamic conditions. Under computer control throughout the pass, programmable test instruments were commanded and data was collected and stored. Data reduction was performed after the pass.

  8. Orbits of the six new satellites of Neptune

    Microsoft Academic Search

    Owen W. M. Jr; R. M. Vaughan; S. P. Synnott

    1991-01-01

    Orbital elements are presented for the six small satellites of Neptune, 1989N1 through 1989N6, discovered by Voyager 2. Details of the image and orbit analyses are examined. The solution for the orbits of the six satellites is presented in terms of geometric classical Keplerian elements. All six are in nearly circular direct orbits; most of the satellites have low inclinations,

  9. Detecting Canopy Water Status Using Shortwave Infrared Reflectance Data From Polar Orbiting and Geostationary Platforms

    Microsoft Academic Search

    Rasmus Fensholt; Silvia Huber; Simon R. Proud; Cheikh Mbow

    2010-01-01

    Various canopy water status estimates have been developed from recent advances in Earth Observation (EO) technology. A promising methodology is based on the sensitivity of shortwave infrared (SWIR) reflectance to variations in leaf water content. This study explores the potential of SWIR-based canopy water status detection from geostationary Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) data

  10. Orbit Determination in Satellite Geodesy

    Microsoft Academic Search

    G. Beutler; U. Hugentobler; T. Schildknecht

    2002-01-01

    For centuries orbit determination in Celestial Mechanics was a synonym for the determination of the six Keplerian elements of a minor planet or a comet in the solar system based on a short time series of (three or more) astrometric places observed from one or more observatories on the Earth surface. With the advent of the space age the problem

  11. Nexrad-In-Space - A Geostationary Satellite Doppler Weather Radar for Hurricane Studies

    NASA Astrophysics Data System (ADS)

    Im, E.; Chandrasekar, V.; Chen, S. S.; Holland, G. J.; Kakar, R.; Lewis, W. E.; Marks, F. D.; Smith, E. A.; Tanelli, S.; Tripoli, G. J.

    2007-12-01

    The Nexrad-In-Space (NIS) is a revolutionary atmospheric radar observation concept from the geostationary orbiting platform. It was developed over the last 4 years under the auspices of NASA's Earth Science Instrument Incubator Program (IIP). The NIS radar would provide Ka-band (35 GHz) reflectivity and line-of-sight Doppler velocity profiles over a circular Earth region of approximately 5200 km in diameter with a 12-km horizontal resolution, and a minimum detectable signal of 5 dBZ. The NIS radar achieves its superb sampling capabilities by use of a 35-m diameter, deployable antenna made from lightweight membrane material. The antenna has two transmit-receive array pairs that create a dual-beam, spiral-feed combined profile image of both reflectivity and Doppler velocity approximately every 60 minutes. This sampling time can be shortened even further by increasing the number of transmit-receive array pairs. It is generally recognized that the processes important in governing hurricane intensity and structure span a wide range of spatial and temporal scales. The environmental forcing considerations require a large domain. The vortex response to the environmental forcing ultimately involves convection on small horizontal scales in the eyewall and rainband regions. Resolving this environment-vortex-convection feedback in a numerical model requires observations on the space and time scales necessary to unambiguously define these structures within and surrounding the tropical cyclone. Because the time and space scales of these processes are small, continuous 3-dimensional independent observations of the 3-dimensional wind and precipitation structures will be needed to initialize numerical models critical for this purpose. The proposed NIS Doppler radar would be the first instrument capable of accomplishing this feat at time scales less than hours, and would create the opportunity for hurricane science to enter a new era of understanding and improved prediction. This talk will give a brief summary of the NIS instrument concept, the current technology status, the anticipated impacts on hurricane monitoring and model prediction, and the future science and technology roadmap.

  12. Introduction of empirical parameters deduced from the Hill's equations for satellite orbit determination.

    NASA Astrophysics Data System (ADS)

    Cretaux, J.-F.; Nouel, F.; Valorge, C.; Janniere, P.

    1994-05-01

    The theory of perturbations suggests that, in the calculation of ephemerides, most errors due to mismodeling of the forces acting on a spacecraft are of a resonant nature. Colombo (1986; 1989) has shown that they can be corrected by adjusting a certain number of parameters relative to a simple empirical force inferred from the so-called Hill's equations in spite of the complexity of the error causes: mismodeling of the gravitational field, radiation pressure etc. This principle can not be extended to all types of orbits and are valid only for circular ones (ex: geostationary or low Earth orbit). This force was introduced into an orbit determination software and it was tested on the orbits of the LAGEOS, STARLETTE, SPOT2, TOPEX and finally GPS satellites.

  13. Estimation of SW radiation budget using geostationary satellites and quasi-real-time monitoring of PV power generation

    NASA Astrophysics Data System (ADS)

    Takenaka, H.; Nakajima, T. Y.; Inoue, T.; Takamura, T.; Pinker, R. T.; Teruyuki, N.

    2012-12-01

    Clouds can cool the Earth by reflecting solar radiation and also can keep the Earth warm by absorbing and emitting terrestrial radiation. They are important in the energy balance at the Earth surface and the Top of the Atmosphere (TOA) and are connected complicatedly into the Earth system as well as other climate feedback processes. Thus it is important to estimate Earth's radiation budget for better understanding of climate and environmental change. In this study, we developed the high speed and accurate algorithm for shortwave (SW) radiation budget and it's applied to five geostationary satellites for global analysis. There are validated by SKYNET and BSRN ground observation data. The analysis results showed a distinctive trend of direct and diffuse component of surface SW fluxes in North Pacific and North Atlantic ocean. Similarly, developed algorithm is applied to quasi-real time analysis synchronous to geostationary satellite observation. It enabled highly accurate monitoring of solar radiation and photo voltaic (PV) power generation. It indicates the possibility of the fusion analysis of climate study and renewable energy.

  14. Preliminary orbit determination for lunar satellites.

    NASA Technical Reports Server (NTRS)

    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.

  15. Efficient Symplectic Integration of Satellite Orbits

    Microsoft Academic Search

    Seppo Mikkola

    1999-01-01

    The use of the extended phase space and time transformations for constructing efficient symplectic methods for computing the\\u000a long term behavior of perturbed two?body systems are discussed. Main applications are for artificial satellite orbits. The\\u000a methods suggested here are efficient also for large eccentricities.

  16. An analytical method for satellite orbit prediction

    Microsoft Academic Search

    Lin Liu; Yan-Rong Wang

    2006-01-01

    Orbit prediction of artificial satellites is a key link in space surveillance and real-time tracking. Because of the large number of objects to be tracked and because the required precision is not too high, the analytical method is often used in this connection. Such a method is given in this paper. Here, the periodic variations resulting from the earth's non-spherical

  17. History of on-orbit satellite fragmentations

    NASA Technical Reports Server (NTRS)

    Johnson, N. L.; Gabbard, J. R.; Devere, G. T.; Johnson, E. E.

    1984-01-01

    The causes of on-orbit fragmentations are varied and may be intentional or accidental. The cause of many fragmentations remains unknown. While a few cases are currently under investigation as on-orbit collision candidates, man is directly responsible for the vast majority of artificial debris polluting the near-Earth space environment. It should be emphasized that the number of fragments listed with each event in this document represent only those debris officially cataloged by NORAD. Each known on-orbit satellite fragementation is described within this document in module format. Also listed are pertinent characteristics of each fragmentation event. Comments regarding the nature of the satellite and additional details of the events are given.

  18. Combined system for the compensation of the solar pressure-induced disturbing torque for geostationary satellites

    NASA Astrophysics Data System (ADS)

    Shmatov, S. I.; Mordvinkin, A. S.

    2014-12-01

    The problem is considered of determining the shape and dimensions of the passive component in a combined system for offsetting the solar pressure-induced disturbing torque for geostationary spacecraft with asymmetrical solar arrays. The problem statement, numerical solution algorithm, and calculated results are presented. The resulting shape, the study suggests, not only has the required compensation properties but is also the most efficient from the standpoint of manufacture and functional reliability.

  19. Nodding feed antenna for communications with satellites in synchronous orbit

    NASA Technical Reports Server (NTRS)

    Smetana, J.; Zavesky, R.

    1978-01-01

    The design, fabrication, and performance of a parabolic, ground receiving antenna system with a feed that nods in one axis producing a maximum beam deviation 1.1 deg from boresight is described. The antenna design was: (1)to lower the weight (and the subsequent cost) of the supporting structure and the actuator motors for a tracking antenna by moving just the feed; (2) to use a manual tracking system eliminating the need for expensive electronic controls or computers; (3) to provide for several hours of unattended operation; and (4)to permit operation of the antenna by unskilled personnel. Also described are some physical and orbital phenomenon that effect the operation or design of the antenna. One is the motion of a nearly geostationary satellite due to gravitational forces from the sun, the moon, and other stellar bodies. Others are the rotation of the nodding axis and the feed polarization as a function of the location of the station on the earth. A comparison of per unit cost was made for one unit and a quantity of 100.

  20. On-Orbit Satellite Inspection Navigation and v Analysis

    E-print Network

    On-Orbit Satellite Inspection Navigation and v Analysis David Woffinden, David Geller, and David Miller September 2004 SSL #9-04 1 #12;On-Orbit Satellite Inspection Navigation and v Analysis by David;[This page intentionally left blank] #12;On-Orbit Satellite Inspection Navigation and v Analysis

  1. Analysis of Low Earth Orbit Satellite Networks with Inter-satellite Links

    E-print Network

    Sen, Arunabha

    Analysis of Low Earth Orbit Satellite Networks with Inter-satellite Links Arunabha Sen #3 Engineering Arizona State University Tempe, AZ 85287, USA Abstract Low Earth Orbit (LEO) satellite networks Earth Orbit (LEO) satellite networks are increasingly being deployed to carry out communication

  2. The Orbits and Masses of Pluto's Satellites

    NASA Astrophysics Data System (ADS)

    Jacobson, Robert A.; Brozovic, M.

    2012-10-01

    We have fit numerically integrated orbits of Pluto's satellites, Charon, Nix, Hydra, and S/2011 (134340) 1, to an extensive set of astrometric, mutual event, and stellar occultation observations over the time interval April 1965 to July 2011. We did not include the newly discovered satellite S/2012 (134340) 1 because its observation set is insufficient to constrain a numerically integrated orbit. The data set contains all of the HST observations of Charon relative to Pluto which have been corrected for the Pluto center-of-figure center-of-light (COF) offset due to the Pluto albedo variations (Buie et al. 2012 AJ submitted). Buie et al. (2010 AJ 139, 1117 and 1128) discuss the development of the albedo model and the COF offset. We applied COF offset corrections to the remainder of the Pluto relative observations where applicable. The dual stellar occultations in 2008 and 2011 provided precise Pluto_Charon relative positions. We obtain a well determined value for the Pluto system mass, however, the lack of orbital resonances in the system makes it difficult to determine the satellite masses. The primary source of information for the Charon mass is a small quantity of absolute position measurements which are sensitive to the independent motions of Pluto and Charon about the system barycenter. The long term dynamical interaction among the satellites yields a weak determination of Hydra's mass; the masses of the other two satellites are found to be small but indeterminate. We have delivered ephemerides based on our integrated orbits to the New Horizons project along with their expected uncertainties at the time of the New Horizons encounter with the Pluto system. Acknowledgments: The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  3. On the orbit of the LARES satellite

    E-print Network

    Ignazio Ciufolini

    2006-09-20

    This paper is motivated by the recent possibility to find an inexpensive launching vehicle for the LARES satellite, however at an altitude much lower than originally planned for the LAGEOS III/LARES satellite. We present here a preliminary error analysis corresponding to a lower, quasi-polar, orbit, in particular we analyze the effect on the LARES node of the Earth's static gravitational field, and in particular of the Earth's even zonal harmonics, the effect of the time dependent Earth's gravitational field, and in particular of the K1 tide, and the effect of particle drag.

  4. Satellite orbits design using frequency analysis

    NASA Astrophysics Data System (ADS)

    Noullez, A.; Tsiganis, K.; Tzirti, S.

    2015-07-01

    We present here a new method for the efficient computation of periodic orbits, which are of particular interest for low-altitude satellite orbits design in high degree/order, non-axisymmetric gravity models. Our method consists of an iterative filtering scheme, that is itself based on 'Prony's method' of frequency analysis, and is independent of the complexity of the gravity model. Applying this method to the case of a low-altitude lunar orbiter, we show that it converges rapidly, in all models and for all values of altitude and initial inclination studied. Thus, as demonstrated below, one could use it to correct the initial conditions of a desired mission orbit - usually defined within the framework of a simplified model (e.g. the 'J2 problem') - ensuring minimal orbital eccentricity variations and, for very low altitudes, collision avoidance. At the same time, an accurate quasi-periodic decomposition of the orbit is computed, giving a measure of the periodic fluctuations of the orbital parameters.

  5. A simple analytic method for satellite orbit anomalies

    NASA Astrophysics Data System (ADS)

    Song, Weidong; Wang, Ronglan

    Satellite orbit anomalies draw worldwide concerns from users and col-lision warning department. There are three reasons for satellite orbit anomalies: 1atellite orbit maneuver; 2) collision with another space object; 3)explosive fragmentation. When satellite orbit anomalies occur, orbit parameters are likely to undergo sudden changes which are usually characterized by the change of the orbit semimajor axis or mean motion over time. This paper proposed a method for determining the orbit anomalies. This method uses the changes of the orbit semimajor axis over time as a criterion. The outliers are deleted. Through the analysis of nearly 1,000 operational satellites currently in orbit around Earth, the method is proved to be quick and efficient to identify the satellite orbit anomalies. Corresponding author: Weidong Song, Email:swdgh@bit.edu.cn

  6. Semianalytical method of satellite orbit computation

    Microsoft Academic Search

    W.-L. Yang

    1978-01-01

    Artificial satellite orbit calculation is classically analyzed in terms of short-period, long-period, and secular-variation components. While the classical analytical method is sufficiently accurate for the calculation of the short-period perturbation, this paper emphasizes the numerical integration method for computing long-period and secular-variation components. The accuracy achieved by linear extrapolation, the Euler method, and the Runge-Kutta method is discussed.

  7. A new method for determination of satellite orbits by transfer

    Microsoft Academic Search

    Zhigang Li; Xuhai Yang; Guoxiang Ai; Huli Si; Rongchuan Qiao; Chugang Feng

    2009-01-01

    The original idea of a new method for determination of satellite orbits by transfer is from Two-Way Satellite Time and Frequency\\u000a Transfer (TWSTFT). The original method is called “determination of satellite orbit by transfer”. The method is not only for\\u000a determination of satellite orbit but also for the time transfer with high accuracy and precision. The advantage is that the

  8. Orbit-spectrum sharing between the fixed-satellite and broadcasting-satellite services at 12 GHz

    NASA Technical Reports Server (NTRS)

    Reinhart, E. E.

    1974-01-01

    This paper identifies and evaluates strategies for sharing the geostationary orbit in the band 11.7 to 12.2 GHz between domestic systems in the fixed-satellite and broadcasting-satellite services. The effectiveness of two distinct types of sharing strategies, referred to as spectrum division and orbit division, is determined for various deployments of selected baseline systems representing the two services and for various combinations of sharing tactics such as frequency interleaving, crossed-polarization operation, and crossed-beam operation. Effectiveness is measured by the 'utilization factor', defined as the number of channels provided by the baseline systems when using an assigned share of the orbit-spectrum resource, relative to what they could provide if given the entire resource. Computer simulation is used to verify the intra- and interservice interference compatibility of the assumed deployments. It is concluded that total utilization factors close to 100 percent can be achieved with both spectrum-division and properly-chosen orbit-division strategies.

  9. Sentinels in the Sky: Weather Satellites.

    ERIC Educational Resources Information Center

    Haynes, Robert

    This publication describes forecasting weather activity using satellites. Information is included on the development of weather satellites, the National Oceanic and Atmospheric Administration (NOAA) Satellite System (including the polar-orbiting satellites), and the Geostationary Operational Environmental Satellite (GOES). The publication…

  10. COSPAS-SARSAT Satellite Orbit Predictor, Vol 4

    NASA Technical Reports Server (NTRS)

    Friedman, Morton L.; Garrett, James, Major

    1984-01-01

    The satellite orbit predictor is a graphical aid for determining the relationship between the satellite (SARSAT or COSPAS) orbit, antenna coverage of the spacecraft and coverage of the LUTs. The predictor allows the user to quickly visualize if a selected position will probably be detected and is composed of a base map and a satellite track overlay for each satellite. Additionally, a table of equator crossings for each satellite is included.

  11. 6Name ________________________________ Satellite technology is everywhere! Right now, there are over 1587 working satellites orbiting

    E-print Network

    , there are over 1587 working satellites orbiting Earth. They represent over $160 billion in assets to the world years as new services are created, and better technology is developed. Satellites in the lowest orbits affects Earth. Can you come up with at least two ways that the sun could affect a satellite's orbit

  12. Characterizing switching problems in low earth orbit satellite constellations with satellite failures 

    E-print Network

    Wadsworth, Brandon Scott

    1999-01-01

    In this research, we study the ability of LEO satellite constellations to handle data traffic. LEO satellites offer a number of advantages over traditional space based communications via geosynchronous orbit satellites (GEO). However...

  13. Characterizing switching problems in low earth orbit satellite constellations with satellite failures

    E-print Network

    Wadsworth, Brandon Scott

    1999-01-01

    In this research, we study the ability of LEO satellite constellations to handle data traffic. LEO satellites offer a number of advantages over traditional space based communications via geosynchronous orbit satellites (GEO). However...

  14. Diurnal extrapolation for the Earth Radiation Budget with geostationary satellites: examples and error estimates.

    NASA Astrophysics Data System (ADS)

    Viollier, M.; Kandel, R.; Raberanto, P.

    The study is mainly focused on combination of CERES with Meteosat-5. Examples of radiances and flux comparisons are shown between March 2000 and July 2002. They fix the errors due to possible calibration shift and narrowband-to-broadband conversion uncertainties. The Meteosat flux estimates at each half hour combined with the CERES fluxes are then used to compute monthly means. Compared to the ERBE-like extrapolation scheme, the changes are small in the LW domain, but significant in the SW (regional means: ˜ 20 Wm-2, 20S-20N means: ˜ 4 Wm-2 over the Meteosat-5 area). Improvements in this research field are expected from the analysis of the first Geostationary Radiation Budget instrument GERB/Meteosat-8.

  15. Long-Term Prediction of Satellite Orbit Using Analytical Method

    Microsoft Academic Search

    Jae-Cheol Yoon; Hyu-Hong Choi; Byonug-Sun Lee; Jong-Won Eun

    1997-01-01

    A long-term prediction algorithm of geostationary orbit was developed using the analytical method. The perturbation force models include geopotential upto fifth order and degree and luni-solar gravitation, and solar radiation pressure. All of the perturbation effects were analyzed by secular variations, short-period variations, and long-period variations for equinoctial elements such as the semi-major axis, eccentricity vector, inclination vector, and mean

  16. Scientific data stewardship of International Satellite Cloud Climatology Project B1 global geostationary

    E-print Network

    the advances in computing capabilities since 1983 and the need for higher resolution global cloud analysisScientific data stewardship of International Satellite Cloud Climatology Project B1 global, North Carolina, 28801, USA Ken.Knapp@noaa.gov Abstract. The International Satellite Cloud Climatology

  17. Jupiter orbiter lifetime: The hazard of Galilean satellite collision

    NASA Technical Reports Server (NTRS)

    Friedlander, A. L.

    1975-01-01

    The four Galilean satellites of Jupiter present a long-term collision hazard to an uncontrolled orbiting spacecraft that repeatedly enters the spatial region occupied by the satellites. Satellite close encounters and the likelihood of collision over a wide range of initial orbit conditions were analyzed. The effect of orbit inclination was of key interest. The scope of the analysis was restricted to orbital dynamic considerations alone, i.e. the question of biological contamination given the event of collision was not considered. A quarantine or orbiter lifetime of 50 years was assumed. This time period begins at spacecraft shutdown following completion of the mission objectives. A numerical approach was adopted wherein each initial orbit is propagated for 50 years, and satellite closest encounter distances recorded on every revolution. The computer program includes approximations of the three major perturbation effects on the long-term motion of the orbiter: (1) Jupiter oblateness, (2) solar gravity, and (3) satellite gravity.

  18. Numerical simulations of the decay of satellite galaxy orbits

    Microsoft Academic Search

    D. N. C. Lin; S. Tremaine

    1983-01-01

    A multiple three-body technique is used to study the orbital evolution of satellite galaxies which is similar to the N-body method but neglects two-body forces between stars in the halo of the parent galaxy. It is found that, for satellites orbiting within the halo, Chandrasekhar's (1960) dynamical friction formula accurately describes the orbital decay rate, including its variation with satellite

  19. Orbital evolution of the Galilean satellites

    NASA Technical Reports Server (NTRS)

    Greenberg, R.

    1982-01-01

    The orbital motions of the Galilean satellites exert dramatic control over their physical properties (most notably Io's) through tidal heating. In turn, tidal dissipation in the satellites, as well as in Jupiter, has governed the evolution of the orbits and, in particular, of the Laplace resonance. If the system started out of the resonance and evolved into it, forced eccentricities would have increased with time. Hence, the tidal melting of Io and the cracking of Europa'a surface may have occurred relatively recently. This theory requires that Jupiter's tidal dissipation factor be greater than about two million, a rather low value (high rate of tidal dissipation) compared with most models of Jovian interior processes. Alternatively, the system may have started even deeper in the resonance than it is today, a scenario which is consistent with larger values of the tidal dissipation factor. This model, with its correspondingly large initial forced eccentricities, would imply (1) that Io melted early and fast, and may have remained molten with only a thin solid skin until the present and (2) that the water mantles of both Europa and Ganymede remained largely molten for considerably longer than Callisto did, but later froze as their eccentricities and tidal heating decreased.

  20. Digital meteorological radar data compared with digital infrared data from a geostationary meteorological satellite 

    E-print Network

    Henderson, Rodney Stuart

    1979-01-01

    , for providing the satellite data and advice regarding its use. Mr. Ray McAnelly, for his generation of the digital radar data used in this study, Mr. T. O. Haig, also of the Space Science and Engineering Center, for information on the McIDAS system. Mrs... (Continued) CHAPTER Page 4. Basic Characteristics of In'rared Satellite Data. 5. McIDAS Data 6. Data Reduction and Display 26 27 29 IV. COMPARISON OF DIGITAL RADAR AND SATELLITE DATA 38 1. The Ba sis for the Comparison 2. First Tilt...

  1. Towards High Spa-Temporal Resolution Estimates of Surface Radiative Fluxes from Geostationary Satellite Observations for the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Niu, X.; Yang, K.; Tang, W.; Qin, J.

    2014-12-01

    Surface Solar Radiation (SSR) plays an important role of the hydrological and land process modeling, which particularly contributes more than 90% to the total melt energy for the Tibetan Plateau (TP) ice melting. Neither surface measurement nor existing remote sensing products can meet that requirement in TP. The well-known satellite products (i.e. ISCCP-FD and GEWEX-SRB) are in relatively low spatial resolution (0.5º-2.5º) and temporal resolution (3-hourly, daily, or monthly). The objective of this study is to develop capabilities to improved estimates of SSR in TP based on geostationary satellite observations from the Multi-functional Transport Satellite (MTSAT) with high spatial (0.05º) and temporal (hourly) resolution. An existing physical model, the UMD-SRB (University of Maryland Surface Radiation Budget) which is the basis of the GEWEX-SRB model, is re-visited to improve SSR estimates in TP. The UMD-SRB algorithm transforms TOA radiances into broadband albedos in order to infer atmospheric transmissivity which finally determines the SSR. Specifically, main updates introduced in this study are: implementation at 0.05º spatial resolution at hourly intervals integrated to daily and monthly time scales; and improvement of surface albedo model by introducing the most recently developed Global Land Surface Broadband Albedo Product (GLASS) based on MODIS data. This updated inference scheme will be evaluated against ground observations from China Meteorological Administration (CMA) radiation stations and three TP radiation stations contributed from the Institute of Tibetan Plateau Research.

  2. Geostationary Operational Environmental Satellite (GOES)-R hyperspectral environmental suite (HES) implementation

    Microsoft Academic Search

    Gene Martin; Sandra Cauffman; Marty Davis; Edward Grigsby; Andrew Carson; Marvin Maxwell; Karl Klett; Joe Criscione; Curt Niblack

    2004-01-01

    This paper outlines the requirements and methodologies for development of the NOAA\\/NASA GOES-R Hyperspectral Environmental Suite (HES) instrument. The HES instrument is currently being developed within the framework of the GOES Program to fulfill the future needs and requirements of the National Environmental Satellite, Data, and Information Service (NESDIS). As an integral component of the GOES-R series satellites, HES will

  3. Implementation of a state of the art automated system for the production of cloud/water vapor motion winds from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Velden, Christopher

    1995-01-01

    The research objectives in this proposal were part of a continuing program at UW-CIMSS to develop and refine an automated geostationary satellite winds processing system which can be utilized in both research and operational environments. The majority of the originally proposed tasks were successfully accomplished, and in some cases the progress exceeded the original goals. Much of the research and development supported by this grant resulted in upgrades and modifications to the existing automated satellite winds tracking algorithm. These modifications were put to the test through case study demonstrations and numerical model impact studies. After being successfully demonstrated, the modifications and upgrades were implemented into the NESDIS algorithms in Washington DC, and have become part of the operational support. A major focus of the research supported under this grant attended to the continued development of water vapor tracked winds from geostationary observations. The fully automated UW-CIMSS tracking algorithm has been tuned to provide complete upper-tropospheric coverage from this data source, with data set quality close to that of operational cloud motion winds. Multispectral water vapor observations were collected and processed from several different geostationary satellites. The tracking and quality control algorithms were tuned and refined based on ground-truth comparisons and case studies involving impact on numerical model analyses and forecasts. The results have shown the water vapor motion winds are of good quality, complement the cloud motion wind data, and can have a positive impact in NWP on many meteorological scales.

  4. Pulsed plasma thruster of erosion type for a geostationary artificial earth satellite

    NASA Astrophysics Data System (ADS)

    Rudikov, A. I.; Antropov, N. N.; Popov, G. A.

    1993-10-01

    The design of an erosion pulsed plasma thruster (PPT) with a pulse energy of 200-300 J, capable of maintaining the altitude of a 500-kg satellite for 10 years, is described. A thruster with a lifetime of 2-3 x 10 exp 7 pulses produces a total pulse of 2.5 x 10 exp 5 Ns while consuming up to 13 kg of propellant (Teflon). It is estimated that the total mass of the PPT will not exceed 50-60 kg. Even in the case of two-fold redundancy, the thruster set mass should not exceed 0.20-0.25 of the satellite mass.

  5. An assessment of Saharan dust loading and the corresponding cloud-free longwave direct radiative effect from geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Brindley, Helen E.; Russell, Jacqueline E.

    2009-12-01

    Previously, a method was developed to quantify Saharan dust optical thickness and simultaneously diagnose the cloud-free longwave dust direct radiative effect (LWDRE) over a single surface site using observations from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) and Geostationary Earth Radiation Budget (GERB) instrument both flying on the Meteosat Second Generation series of satellites. In this paper the overall utility of the approach is investigated using a more comprehensive suite of observations, and the inherent uncertainties associated with the method are assessed. On the basis of these findings, the approach has been updated to account for the effects of varying dust layer altitude. Comparisons with colocated observations from the Aerosol Robotic Network (AERONET) and Multiangle Imaging Spectroradiometer (MISR) using the modified approach indicate that the visible optical thickness at 0.55 ?m, ?055, can be obtained with an RMS uncertainty of ˜0.3 over North Africa and Arabia during sunlit hours, while monthly maps of optical depth derived over this region through spring and summer of 2006 show similar variability to that identified in the long-term climatology provided by the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index. The regional mean instantaneous cloud-free LWDRE and associated LW radiative efficiency estimated from GERB over the same period are relatively constant with season, ranging from 9 to 11 W m-2 and 16-20 W m-2?055-1, respectively.

  6. A system for autonomous navigation and attitude determination in geostationary orbit

    Microsoft Academic Search

    P. Maute; O. Defonte

    1990-01-01

    The results of a joint CNES-Aerospatiale study leading to an autonomous navigation and three-axis attitude determination system are presented. The principles, software architecture, preprocessing, navigator, orbit control, and hardware configuration of the system are described. The optimization process is described as well with attention given to sensor architecture and operational modes. It is found that the presence of an additional

  7. Geostationary Operational Environmental Satellites (GOES): R series hyperspectral environmental suite (HES) overview

    Microsoft Academic Search

    Gene Martin; Joseph C. Criscione; Sandra A. Cauffman; Martin A. Davis

    2004-01-01

    The Hyperspectral Environmental Suite (HES) instrument is currently under development by the NASA GOES-R Project team within the framework of the GOES Program to fulfill the future needs and requirements of the National Environmental Satellite, Data, and Information Service (NESDIS) Office. As part of the GOES-R instrument complement, HES will provide measurements of the traditional temperature and water vapor vertical

  8. Quasi-geostationary viewing of high latitudes for Weather, Climate and Air quality data using highly elliptical orbits: PCW/PHEOS-WCA

    NASA Astrophysics Data System (ADS)

    McConnell, J. C.; McElroy, C. T.; Sioris, C. E.; Walker, K. A.; Buijs, H.; Rahnama, P.; Trishchenko, A. P.; Garand, L.; Nassar, R.; Martin, R. V.; Bergeron, M.; O'Neill, N. T.

    2012-12-01

    Arctic climate is changing and the multi-year sea-ice cover is disappearing more rapidly that climate models estimate. With declining ice cover, the Arctic Ocean will likely be subject to increased shipping traffic in addition to exploration activity for natural resources with a concomitant increase in air pollution. Thus there is a need to monitor the polar region and an important method that can address many of the atmospheric issues is by quasi-geostationary viewing at high temporal resolution. For this reason, several Canadian government departments led by the Canadian Space Agency (CSA) are proposing the PCW (Polar Communications and Weather) mission to provide improved communications and critically important meteorological and air quality information for the Arctic, in particular wind information using an operational meteorological imager. Two satellites are planned to be in a highly eccentric orbit with apogee at ~ 40,000 km over the Arctic in order to have both quasi-geostationary viewing over the Arctic and environs and 24x7 coverage in the MIR and solar reflected light (UV-Vis-NIR) in the summer period. The planned operational meteorological instrument is a 21-channel spectral imager with UV, visible, NIR and MIR channels similar to MODIS or ABI. This presentation will focus on PHEOS WCA (Polar Highly Elliptical Orbital Science Weather, Climate and Air quality) mission, which is an atmospheric science complement to the operational PCW mission. The PHEOS WCA instrument package consists of FTS and UVS imaging sounders with viewing range of ~4.5 degrees or a FoR ~ 3400x3400 km2 from near apogee. The spatial resolution at apogee of each imaging sounder is targeted to be 10×10 km2 or better and the image repeat time is targeted at ~ 1-2 hours or better. The FTS has 4 bands that span the MIR and NIR. The MIR bands cover 700-1500 cm-1 and 1800-2700 cm-1 with a spectral resolution of 0.25 cm-1 i.e., a similar spectral resolution to IASI. They should provide vertical tropospheric profiles of temperature and water vapour in addition to partial columns of other gases of interest for air quality such as O3, CO, HCN, CH3OH, etc. and also CO2 and CH4. The two NIR bands cover 5990-6010 cm-1 (0.25 cm-1) and 13060-13168 cm-1 (0.5 cm-1) and target columns of CO2 and CH4 and the O2-A band for surface pressure, aerosol OD and albedo. The UVS is an imaging spectrometer that covers the spectral range of 280 - 650 nm with 0.9 nm resolution and targets the tropospheric column densities of O3 and NO2. It is also planned to obtain the tropospheric columns of BrO, SO2, HCHO and (HCO)2 on an opportunity basis and the aerosol index (AI) as well as stratospheric columns of O3, NO2 and BrO. One of the important goals for PHEOS-FTS is to measure changes in CO2 and CH4 throughout the day-lit hours in the NIR near apogee. The imaging design is to be sufficiently flexible so that it can be directed at special events and the FoR reduced to have more rapid spatial coverage. In this presentation we will outline the scientific objectives, status of retrieval algorithms and also the viewing geometry necessary with 2 satellites and the outcome of the PHEOS WCA Phase A study, funded by the CSA, which was completed in the spring of 2012.

  9. The east Pacific ITCZ complex (northern only, southern only, double) in 30 years of geostationary satellite data

    NASA Astrophysics Data System (ADS)

    Haffke, C. M.; Magnusdottir, G.; Henke, D.; Smyth, P.

    2014-12-01

    The double Intertropical Convergence Zone (ITCZ) in the east Pacific has been identified in previous observational studies in terms of time mean data, e.g. monthly mean fields. Little is known about the instantaneous occurrence of this feature. Here we use a new method for automated daily identification of convection associated with the east Pacific ITCZ in visible and infrared geostationary satellite images from 1980-2012. The method uses the satellite images to extract information about the spatial features of the clouds comprising the convergence zones. Features are then used as input to a temporal classification algorithm that is based on a combination of hidden semi-Markov model and support vector machine methods. Five 'states' are used to describe the location of the ITCZ: northern hemisphere only (nITCZ), southern hemisphere only (sITCZ), double ITCZ (dITCZ), ITCZ located directly on the equator (eITCZ), and no ITCZ present (aITCZ). Most of the year, particularly from May-Dec, is dominated by the nITCZ state. The boreal springtime is characterized by a high number of days classified as dITCZ, but the state of the ITCZ is quite variable during this time and can frequently transition between dITCZ, nITCZ, sITCZ, and aITCZ states. Our results will show ITCZ variability in terms of the different states on daily to interannual time scales. We will show how the large scale environment, including SST and atmospheric moisture availability, influences the occurrence of each ITCZ state, focusing on the dITCZ in the boreal springtime.

  10. The influence of satellite flexibility on orbital motion

    Microsoft Academic Search

    A. K. Misra; V. J. Modi

    1978-01-01

    The orbital perturbations induced by the librational motion and flexural oscillations are studied for satellites having large flexible appendages. Using a Lagrangian procedure, the equations for coupled motion are derived for a satellite having an arbitrary number of appendages in the nominal orbital plane and two flexible members normal to it. The formulation enables one to study the influence of

  11. Circumnutations of sunflower hypocotyls in satellite orbit

    NASA Technical Reports Server (NTRS)

    Brown, A. H.; Chapman, D. K.; Lewis, R. F.; Venditti, A. L.

    1990-01-01

    The principal objective of the research reported here was to determine whether a plant's periodic growth oscillations, called circumnutations, would persist in the absence of a significant gravitational or inertial force. The definitive experiment was made possible by access to the condition of protracted near weightlessness in an earth satellite. The experiment, performed during the first flight of Spacelab on the National Aeronautics and Space Administration shuttle, Columbia, in November and December, 1983, tested a biophysical model, proposed in 1967, that might account for circumnutation as a gravity-dependent growth response. However, circumnutations were observed in microgravity. They continued for many hours without stimulation by a significant g-force. Therefore, neither a gravitational nor an inertial g-force was an absolute requirement for initiation [correction of initation] or continuation of circumnutation. On average, circumnutation was significantly more vigorous in satellite orbit than on earth-based clinostats. Therefore, at least for sunflower (Helianthus annuus L.) circumnutation, clinostatting is not the functional equivalent of weightlessness.

  12. Orbit Modelling for Satellites Using the NASA Prediction Bulletins

    NASA Technical Reports Server (NTRS)

    Bonavito, N. L.; Koch, D. W.; Maslyar, G. A.; Foreman, J. C.

    1976-01-01

    For some satellites the NASA Prediction Bulletins are the only means available to the general user for obtaining orbital information. A computational interface between the information given in the NASA Prediction Bulletins and standard orbit determination programs is provided. Such an interface is necessary to obtain accurate orbit predictions. The theoretical considerations and their computational verification in this interface modelling are presented. This analysis was performed in conjunction with satellite aided search and rescue position location experiments where accurate orbits of the Amateur Satellite Corporation (AMSAT) OSCAR-6 and OSCAR-7 spacecraft are a prerequisite.

  13. The Characteristics of Critical Inclination of Satellite Orbit

    Microsoft Academic Search

    Hyun Joo Yi; Kyu-Hong Choi

    1993-01-01

    The orbit characteristics and perturbation effects of an artificial satellite with critical inclination have been studied. The critical inclination problem in artificial satellite theory is treated as Ideal Resonance Problem(IRP). The KITSAT-1 satellite launched by Arian 42P at Guiana in August 11, 1992 has orbital inclination close to the critical value cos-1(1\\/51\\/2). In that case, there is a singularity in

  14. Attitude dynamics and control of satellites orbiting rotating asteroids

    Microsoft Academic Search

    K. D. Kumar

    2008-01-01

    Summary  The paper focuses on the attitude dynamics and control of satellites orbiting a rotating asteroid. The general formulation\\u000a of the satellite equations of motion in an equatorial eccentric orbit is obtained through the Lagrangian method. The linearized\\u000a system model is derived and the stability analysis is presented. The control laws for three-axis attitude control of satellites\\u000a are developed and a

  15. Precise science orbits for the Swarm satellite constellation

    NASA Astrophysics Data System (ADS)

    Van Den IJssel, Jose; Visser, Pieter N. A. M.; Doornbos, Eelco; De Teixeira da Encarnacao, Joao

    Swarm, the 4th Earth Explorer mission by the European Space Agency (ESA), was launched in November 2013 to study the dynamics of the Earth's magnetic field and its interaction with the Earth system. To better distinguish between the different sources of magnetism, the mission consists of three identical satellites, flying in carefully selected near-polar orbits. Two satellites will fly side-by-side at an initial altitude of 460 km, and slowly descend to around 300 km during the mission. The third satellite remains in a higher orbit of about 510 km altitude. To geolocate the Swarm observations, each of these satellites is equipped with a 8-channel, dual-frequency GPS receiver for precise orbit determination. On-board laser retro-reflectors provide the opportunity to validate the orbits computed from the GPS observations. The computation of precise orbits for the Swarm satellites is part of the activities performed in the Swarm Satellite Constellation Application and Research Facility (SCARF), supported by ESA. This consortium of several research institutes is responsible for providing the Swarm Level 2 products, including precise science orbits. A brief overview is given of the adopted orbit determination strategy, together with a preliminary assessment of the Swarm GPS receiver performance. Precise orbit determination results for the first months of data are presented, including a validation based on satellite laser ranging measurements.

  16. DRAG COEFFICIENT ESTIMATION USING SATELLITE ATTITUDE AND ORBIT DATA

    E-print Network

    Maroncelli, Mark

    PENNSTATE _ DRAG COEFFICIENT ESTIMATION USING SATELLITE ATTITUDE AND ORBIT DATA 2Lt. Christopher L for spacecraft in a variety of orbits and solar cycle conditions is generally assumed to be a constant value of 2 of drag using orbital data gathered from NASA's Swift spacecraft. In order to accomplish this task

  17. NASA Technical Paper 3394 Lifetimes of Lunar Satellite Orbits

    E-print Network

    Rathbun, Julie A.

    NASA Technical Paper 3394 Lifetimes of Lunar Satellite Orbits Kurt W. Meyer The George Washington parking orbit issues. Additionally, we would also like to thank Robert Tolson of Tile George Washingt,e, est ions. #12;Summary Lifetimes of low-altitude lunar orbits are studied in this report to identify

  18. Low Earth Orbiter Satellite Precise Orbit Determination and its Precision Analysis from Satellite-Borne GPS with LP Estimation

    Microsoft Academic Search

    Zheng Zuoya; Dang Yamin; Lu Xiushan; Tian Maoyi

    2009-01-01

    To get high precise low earth orbiter (LEO) satellite orbit from satellite-borne GPS data, the satellite-borne GPS carrier phase measurements must be used, but there are still remnant cycle-slips after GPS data pre-processing. Least Square is an optimal method to solve parameters if the residual obeys to normal distribution, but it is difficult to process data with systematic error, LP

  19. Orbit determination accuracies using satellite-to-satellite tracking

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.; Argentiero, P. D.; Schmid, P. E.

    1977-01-01

    The uncertainty in relay satellite sate is a significant error source which cannot be ignored in the reduction of satellite-to-satellite tracking data. Based on simulations and real data reductions, it is numerically impractical to use simultaneous unconstrained solutions to determine both relay and user satellite epoch states. A Bayesian or least squares estimation technique with an a priori procedure is presented which permits the adjustment of relay satellite epoch state in the reduction of satellite-to-satellite tracking data without the numerical difficulties introduced by an ill-conditioned normal matrix.

  20. Evaluation of Bulk Charging in Geostationary Transfer Orbit and Earth Escape Trajectories Using the Numit 1-D Charging Model

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Coffey, Victoria N.; Parker, Linda N.; Blackwell, William C., Jr.; Jun, Insoo; Garrett, Henry B.

    2007-01-01

    The NUMIT 1-dimensional bulk charging model is used as a screening to ol for evaluating time-dependent bulk internal or deep dielectric) ch arging of dielectrics exposed to penetrating electron environments. T he code is modified to accept time dependent electron flux time serie s along satellite orbits for the electron environment inputs instead of using the static electron flux environment input originally used b y the code and widely adopted in bulk charging models. Application of the screening technique ts demonstrated for three cases of spacecraf t exposure within the Earth's radiation belts including a geostationa ry transfer orbit and an Earth-Moon transit trajectory for a range of orbit inclinations. Electric fields and charge densities are compute d for dielectric materials with varying electrical properties exposed to relativistic electron environments along the orbits. Our objectiv e is to demonstrate a preliminary application of the time-dependent e nvironments input to the NUMIT code for evaluating charging risks to exposed dielectrics used on spacecraft when exposed to the Earth's ra diation belts. The results demonstrate that the NUMIT electric field values in GTO orbits with multiple encounters with the Earth's radiat ion belts are consistent with previous studies of charging in GTO orb its and that potential threat conditions for electrostatic discharge exist on lunar transit trajectories depending on the electrical proper ties of the materials exposed to the radiation environment.

  1. Quasi-real-time monitoring of SW radiation budget using geostationary satellite for Climate study and Renewable energy. (Invited)

    NASA Astrophysics Data System (ADS)

    Takenaka, H.; Nakajima, T. Y.; Kuze, H.; Takamura, T.; Pinker, R. T.; Nakajima, T.

    2013-12-01

    Solar radiation is the only source of energy that drives the weather and climate of the Earth's surface. Earth is warmed by incoming solar radiation, and emitted energy to space by terrestrial radiation due to its temperature. It has been kept to the organisms viable environment by the effect of heating and cooling. Clouds can cool the Earth by reflecting solar radiation and also can keep the Earth warm by absorbing and emitting terrestrial radiation. They are important in the energy balance at the Earth surface and the Top of the Atmosphere (TOA) and are connected complicatedly into the Earth system as well as other climate feedback processes. Thus it is important to estimate Earth's radiation budget for better understanding of climate and environmental change. We have shared several topics related to climate change. Energy issues close to the climate change, it is an environmental problems. Photovoltaics is one of the power generation method to converts from solar radiation to electric power directly. It does not emit greenhouse gases during power generation. Similarly, drainage, exhaust, vibration does not emit. PV system can be distributed as a small power supply in urban areas and it can installed to near the power demand points. Also solar thermal is heat generator with high efficiency. Therefor it is an effective energy source that the solar power is expected as one of the mitigation of climate change (IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation). It is necessary to real-time-monitoring of the surface solar radiation for safety operation of electric power system. We introduce a fusion analysis of renewable energy and Quasi-real-time analysis of SW radiation budget. Sample of estimated PV power mapping using geostationary satellite.

  2. The Role of Orograph and Parallax Corrections on High Resolution Geostationary Satellite Rainfall Estimates for Flash Flood Applications

    NASA Technical Reports Server (NTRS)

    Vicente, Gilberto A.; Davenport, Clay; Scofield, Rod

    1999-01-01

    The current generation of geosynchronous satellites exhibits considerably improved capabilities in the area of resolution, gridding accuracy, and sampling frequency as compared to their predecessors. These improvements have made it possible to accurately observe the life cycle of small scale, short-live phenomenon like rapidly developing thunderstorms, at a very high spatial and temporal resolutions. While the gain in the improved resolution is not significant for synoptic scale cloud systems, it plays a major role on the computation of precipitation values for mesoscale and stonn scale systems. Two of the important factor on the accurate precision of precipitation from satellite imagery are the position of the cloud tops as viewed by the satellite and the influence of orographic effects on the distribution of precipitation. The first problem has to do with the fact that the accurate estimation of precipitation from data collected by a satellite in geosynchronous orbit requires the knowledge of the exact position of the cloud tops with respect to the ground below. This is not a problem when a cloud is located directly below the satellite; at large viewing angles the geographic coordinates on satellite images are dependent on cloud heights and distance from the sub-satellite point. The latitude and longitude coordinates for high convective cloud tops are displaced away from the sub-satellite point and may be shifted by as much as 20 Km from the sea level coordinates. The second problem has to do with the variations in rainfall distribution with elevation. Ground observations have shown that precipitation amounts tend to increase with height and that the slope of the hill or mountain that is facing the prevailing wind normally receives greater rainfall then do the lee slopes. The purpose of the study is to show the recent developments at the Office of Research and Applications (ORA) at the National Oceanic and Atmospheric Administration (NOAA/NESDIS) in Camp Springs, MD, USA, to adjust any satellite rainfall estimation technique and account for orographic and parallax corrections. Description and examples of the procedure applied to the current NOAA/NESDIS experimental satellite rainfall estimation technique for flash flood applications will be presented at the conference.

  3. Orbital evolution and origin of the Martian satellites

    NASA Astrophysics Data System (ADS)

    Szeto, A. M. K.

    1983-07-01

    The orbital evolution of the Martian satellites is considered from a dynamical point of view. Celestial mechanics relevant to the calculation of satellite orbital evolution is introduced and the physical parameters to be incorporated in the modeling of tidal dissipation are discussed. Results of extrapolating the satellite orbits backward and forward in time are presented and compared with those of other published work. Collision probability calculations and results for the Martian satellite system are presented and discussed. The implications of these calculations for the origin scenarios of the satellites are assessed. It is concluded that Deimos in its present form could not have been captured, for if it had been, it would have collided with Phobos at some point. An accretion model is therefore preferred over capture, although such a model consistent with the likely carbonaceous chondritic composition of the satellites has yet to be established.

  4. Estimating on-orbit optical properties for GNSS satellites

    NASA Astrophysics Data System (ADS)

    Rodriguez Solano, M. Sc. Carlos Javier; Hugentobler, Urs; Steigenberger, Peter

    One of the major uncertainty sources affecting GNSS satellite orbits is the direct solar radiation pressure. Other important though smaller effects are caused by deviations of the satellite from nominal attitude, Earth radiation pressure and thermal re-radiation forces. To compensate such effects, the IGS Analysis Centers usually estimate empirical parameters which fit best the tracking data obtained from a global network of GNSS ground stations to compute orbits at an accuracy level of 2.5 cm for GPS and of 5 cm for GLONASS. On the other hand, there are also accurate physical models for the above mentioned non-conservative forces affecting the GNSS satellites such as the ROCK models for GPS satellites. However, current models fail to predict the real orbit behaviour with sufficient accuracy, mainly due to deviations from nominal attitude, from inaccurately known optical properties, or from aging of the satellite surfaces. In this context an analytical box-wing model has been derived based on the physical interaction between the direct solar radiation and a satellite consisting of a bus (box shape) and solar panels. Furthermore some of the parameters of the box-wing model can be adjusted to fit the GNSS tracking data, namely the fraction of reflected photons of the corresponding satellite surfaces. For this study GNSS orbits are generated based on one year of tracking data from the global IGS network and involving the box-wing model implemented into the Bernese GPS Software. The processing scheme was derived from the one used at the Center for Orbit Determination in Europe (CODE). The resulting satellite orbits are compared with CODE Final Orbits and validated using SLR (Satellite Laser Ranging) tracking data. Additionally, in the case of GPS satellites, the box-wing model and the obtained optical properties are compared directly with a priori models (e.g. ROCK), which deal with the direct solar radiation impacting the satellites.

  5. Application of two special orbits in the orbit determination of lunar satellites

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Hou, Xi-Yun; Tang, Jing-Shi; Liu, Lin

    2014-10-01

    Using inter-satellite range data, the combined autonomous orbit determination problem of a lunar satellite and a probe on some special orbits is studied in this paper. The problem is firstly studied in the circular restricted three-body problem, and then generalized to the real force model of the Earth-Moon system. Two kinds of special orbits are discussed: collinear libration point orbits and distant retrograde orbits. Studies show that the orbit determination accuracy in both cases can reach that of the observations. Some important properties of the system are carefully studied. These findings should be useful in the future engineering implementation of this conceptual study.

  6. Geostationary Operational Environmental Satellite (GOES-N report). Volume 1: Technical

    NASA Astrophysics Data System (ADS)

    1991-12-01

    The GOES-N study consisted of five distinct tasks including: determining replication costs of GOES I-M and GOES-7 in the GOES-N time frame; defining and evaluating modifications to GOES I-M to improve efficiency or reduce costs; and defining evolutionary changes to the GOES I-M design to satisfy National Weather Service (NWS) 1983 and NOAA 1989 requirements. The categorization and disposition of NOAA requirements is reported in volume 1 section 4. Results of the GOES I-M efficiency/cost improvement modifications study are described in Section 7.1. The system concept options 1, 2, and 3 that generally represent the results of the Task 2, 3A, and 3B studies are summarized in Section 7.2. Another result of the GOES-N study, the determination of which NWS 1983 and NOAA 1989 requirements can be met with the three options, is contained in volume 1 section 7. Conclusions and recommendations are covered in volume 1 section 8. Imager, sounder, control system, space environment monitor, search and rescue, weather facsimile, data collection system, and products/process/communications recommendations were extracted from sections 9, 10, and 11. Section 8 also contains conclusions pertaining to programmatic operational satellite issues (prerequisite development strategies, the direct procurement of instruments by the government, protoflight mission, etc.). Sections 9, 10, and 11 address instrument, control system, image/navigation/registration, and other system design considerations and surveys. These sections are supported by the appendices in volume 2.

  7. The Geostationary Fourier Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Key, Richard; Sander, Stanley; Eldering, Annmarie; Miller, Charles; Frankenberg, Christian; Natra, Vijay; Rider, David; Blavier, Jean-Francois; Bekker, Dmitriy; Wu, Yen-Hung

    2012-01-01

    The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for an earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. The GeoFTS instrument is a half meter cube size instrument designed to operate in geostationary orbit as a secondary "hosted" payload on a commercial geostationary satellite mission. The advantage of GEO is the ability to continuously stare at a region of the earth, enabling frequent sampling to capture the diurnal variability of biogenic fluxes and anthropogenic emissions from city to continental scales. The science goal is to obtain a process-based understanding of the carbon cycle from simultaneous high spatial resolution measurements of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) many times per day in the near infrared spectral region to capture their spatial and temporal variations on diurnal, synoptic, seasonal and interannual time scales. The GeoFTS instrument is based on a Michelson interferometer design with a number of advanced features incorporated. Two of the most important advanced features are the focal plane arrays and the optical path difference mechanism. A breadboard GeoFTS instrument has demonstrated functionality for simultaneous measurements in the visible and IR in the laboratory and subsequently in the field at the California Laboratory for Atmospheric Remote Sensing (CLARS) observatory on Mt. Wilson overlooking the Los Angeles basin. A GeoFTS engineering model instrument is being developed which will make simultaneous visible and IR measurements under space flight like environmental conditions (thermal-vacuum at 180 K). This will demonstrate critical instrument capabilities such as optical alignment stability, interferometer modulation efficiency, and high throughput FPA signal processing. This will reduce flight instrument development risk and show that the GeoFTS design is mature and flight ready.

  8. The Geostationary Fourier Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Key, Richard; Sander, Stanley; Eldering, Annmarie; Blavier, Jean-Francois; Bekker, Dmitriy; Manatt, Ken; Rider, David; Wu, Yen-Hung

    2012-01-01

    The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for a geostationary orbit (GEO) earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. GEO allows GeoFTS to continuously stare at a region of the earth for frequent sampling to capture the variability of biogenic fluxes and anthropogenic emissions from city to continental spatial scales and temporal scales from diurnal, synoptic, seasonal to interannual. The measurement strategy provides a process based understanding of the carbon cycle from contiguous maps of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) collected many times per day at high spatial resolution (2.7kmx2.7km at nadir). The CO2/CH4/CO/CF measurement suite in the near infrared spectral region provides the information needed to disentangle natural and anthropogenic contributions to atmospheric carbon concentrations and to minimize uncertainties in the flow of carbon between the atmosphere and surface. The half meter cube size GeoFTS instrument is based on a Michelson interferometer design that uses all high TRL components in a modular configuration to reduce complexity and cost. It is self-contained and as independent of the spacecraft as possible with simple spacecraft interfaces, making it ideal to be a "hosted" payload on a commercial communications satellite mission. The hosted payload approach for measuring the major carbon-containing gases in the atmosphere from the geostationary vantage point will affordably advance the scientific understating of carbon cycle processes and climate change.

  9. High-resolution satellite imagery for mesoscale meteorological studies

    NASA Technical Reports Server (NTRS)

    Johnson, David B.; Flament, Pierre; Bernstein, Robert L.

    1994-01-01

    In this article high-resolution satellite imagery from a variety of meteorological and environmental satellites is compared. Digital datasets from Geostationary Operational Environmental Satellite (GOES), National Oceanic and Atmospheric Administration (NOAA), Defense Meteorological Satellite Program (DMSP), Landsat, and Satellite Pour l'Observation de la Terre (SPOT) satellites were archived as part of the 1990 Hawaiian Rainband Project (HaRP) and form the basis of the comparisons. During HaRP, GOES geostationary satellite coverage was marginal, so the main emphasis is on the polar-orbiting satellites.

  10. A simple method to directly retrieve reference evapotranspiration from geostationary satellite images

    NASA Astrophysics Data System (ADS)

    Cammalleri, C.; Ciraolo, G.

    2013-04-01

    Application of FAO-56 methodology for the assessment of reference evapotranspiration, ET0, is challenging in areas of the world with sparse meteorological network stations. For this reason alternative procedures using remotely observed data have been proposed in the literature. In this work, a simplified version of the Makkink approach [J. Inst. Wat. Eng. 11: 277-288, 1957] was tested in a typical Mediterranean environment (Sicily, Italy). The implemented Makkink approach (MAK) uses remotely estimated solar radiation derived from Meteosat Second Generation (MSG) satellite data and in situ observations of air temperature to assess ET0 at daily time scale. Alternatively, taking advantage of well-defined relationships that exist between seasonality, elevation and air temperature, a deterministic procedure for estimating air temperature inputs used in the MAK approach (named RS) was also tested. This approach allows the assessment of daily ET0 without the need of auxiliary air temperature ground observations. A comparison between the FAO-56 and MAK approaches was performed for 45 sites in Sicily over the period 2007-2010. Assuming FA0-56 as the benchmark, the average accuracy of the MAK methodology was 0.4 mm d-1, with a relative error of 12%. Similar to other applications of the same procedure, the MAK approach showed a slightly underestimation of ET0 high values; however, an average regression slope of 0.96 (and negligible intercept) suggests a satisfactory agreement with the FAO-56 modeled values. Air temperature observations acquired during 2002-2006 were used to calibrate the deterministic relation between air temperature, seasonality (as a function of the DOY) and orography (as a function of elevation). For the period 2007-2010, the RS approach performs similarly to MAK, with an average difference of less than 0.05 mm d-1. Analysis of monthly, seasonal and yearly ET0 maps shows a slight decrease in RS performance during June and July; nevertheless, the differences between MAK and RS approaches are negligible at all analyzed temporal scales.

  11. A Numerical Testbed for Remote Sensing of Aerosols, and its Demonstration for Evaluating Retrieval Synergy from a Geostationary Satellite Constellation of GEO-CAPE and GOES-R

    NASA Technical Reports Server (NTRS)

    Wang, Jun; Xu, Xiaoguang; Ding, Shouguo; Zeng, Jing; Spurr, Robert; Liu, Xiong; Chance, Kelly; Mishchenko, Michael I.

    2014-01-01

    We present a numerical testbed for remote sensing of aerosols, together with a demonstration for evaluating retrieval synergy from a geostationary satellite constellation. The testbed combines inverse (optimal-estimation) software with a forward model containing linearized code for computing particle scattering (for both spherical and non-spherical particles), a kernel-based (land and ocean) surface bi-directional reflectance facility, and a linearized radiative transfer model for polarized radiance. Calculation of gas absorption spectra uses the HITRAN (HIgh-resolution TRANsmission molecular absorption) database of spectroscopic line parameters and other trace species cross-sections. The outputs of the testbed include not only the Stokes 4-vector elements and their sensitivities (Jacobians) with respect to the aerosol single scattering and physical parameters (such as size and shape parameters, refractive index, and plume height), but also DFS (Degree of Freedom for Signal) values for retrieval of these parameters. This testbed can be used as a tool to provide an objective assessment of aerosol information content that can be retrieved for any constellation of (planned or real) satellite sensors and for any combination of algorithm design factors (in terms of wavelengths, viewing angles, radiance and/or polarization to be measured or used). We summarize the components of the testbed, including the derivation and validation of analytical formulae for Jacobian calculations. Benchmark calculations from the forward model are documented. In the context of NASA's Decadal Survey Mission GEOCAPE (GEOstationary Coastal and Air Pollution Events), we demonstrate the use of the testbed to conduct a feasibility study of using polarization measurements in and around the O2 A band for the retrieval of aerosol height information from space, as well as an to assess potential improvement in the retrieval of aerosol fine and coarse mode aerosol optical depth (AOD) through the synergic use of two future geostationary satellites, GOES-R (Geostationary Operational Environmental Satellite R-series) and TEMPO (Tropospheric Emissions: Monitoring of Pollution). Strong synergy between GEOS-R and TEMPO are found especially in their characterization of surface bi-directional reflectance, and thereby, can potentially improve the AOD retrieval to the accuracy required by GEO-CAPE.

  12. The National Polar-orbiting Operational Environmental Satellite System

    Microsoft Academic Search

    H. Bloom

    2004-01-01

    The tri-agency Integrated Program Office (IPO) is responsible for managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the current military and civilian operational polar-orbiting ``weather'' satellites. The Northrop Grumman Space Technology - Raytheon team was competitively selected in 2002 as the Acquisition and Operations contractor team to develop, integrate, deploy, and operate NPOESS

  13. LARES succesfully launched in orbit: satellite and mission description

    E-print Network

    Paolozzi, Antonio

    2013-01-01

    On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically 'frame dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei-Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation...

  14. WARC and CCIR support for spectrum-orbit planning

    NASA Technical Reports Server (NTRS)

    Sawitz, P. H.

    1980-01-01

    Papers prepared for the use of the U.S. delegation to the 1979 World Administrative Radio Conference; papers contributed to the National CCIR study groups on broadcasting satellites and spectrum-orbit utilization; responses to specific requests for technical analyses and evaluations; and papers presented at technical conferences on related topics are presented. Nonlinear optimization methods for finding optimum positions of satellites in the fixed satellite service; the effects of geography on the use of the geostationary orbit; intercontinental orbit sharing; traffic coordination in interfering satellites operating in the fixed satellite service; and domestic fixed and broadcasting satellite systems are covered. A possible channel orbit plan for broadcasting satellite service in the U.S. and Canada; polarization for broadcasting satellite systems; and the communication capacity of the geostationary satellite orbit are also examined.

  15. Stability limits for the quasi-satellite orbit

    Microsoft Academic Search

    S. Mikkola; K. Innanen; P. Wiegert; M. Connors; R. Brasser

    2006-01-01

    An asteroid moving around the Sun having approximately the same mean motion and mean longitude as a planet, but a different eccentricity, circles the planet like a retrograde satellite even when the distance is large enough so that it is not a bound satellite. If the orbits are coplanar, then the motion is stable in the secular approximation. When the

  16. Lunar tidal acceleration from earth satellite orbit analyses

    Microsoft Academic Search

    Anny Cazenave; Sylviane Daillet

    1981-01-01

    Results are presented for the M2 and O1 ocean tides based on the Starlette satellite orbit analyses from which the tidal acceleration of the moon is derived. The solution for M2 is consistent with previous satellite solutions; for O1 a phase lag is found which is approximately zero. The uncertainty is still large, but there is an indication that the

  17. Robust Capture and Transfer Trajectories for Planetary Satellite Orbiters

    Microsoft Academic Search

    M. E. Paskowitz; D. J. Scheeres

    2006-01-01

    The dynamics of temporarily captured trajectories in the Hill three-body problem is studied, with application to orbits about Jupiter's satellite Europa. By the use of a model that includes the tidal force of Jupiter, the phase space of capture trajectories is numerically determined and trajectories are identified that do not impact with the planetary satellite or escape over long periods

  18. Long-term prediction of GPS satellite orbit

    Microsoft Academic Search

    Tin-An Hsu; Li-Sheng Wang; Fan-Ren Chang; Yi-Fen Tseng

    2010-01-01

    The issue of long-term prediction of GPS satellite orbit is addressed in this paper. Instead of the curve-fitting method, Newton's equations of motion for the satellite is integrated to predict the position of the GPS satellites in a few days. Various effects, including that of the non-spherical Earth, the Sun-Earth gravitational force, and Solar radiation pressure, are taken into account.

  19. Effect of Resonance-Oblateness Coupling on a Satellite Orbit

    Microsoft Academic Search

    C. A. Wagner

    1975-01-01

    Second-order effects of the coupling between geopotential resonance and oblateness on a satellite orbit are calculated. These effects arise from the interaction of resonance with the secular changes of the orbit's node, perigee, and mean anomaly. They have the same period and phase as first-order resonance perturbations. But their amplitudes are proportional to the square of the period and dominate

  20. G-MG Satellite

    NSDL National Science Digital Library

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: A satellite orbiting the earth uses radar to communicate with two control stations on the earth's surface. The satellite is in a geostationary orbit. T...

  1. Weather satellite launched

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2006-06-01

    NASA launched on 24 May the weather satellite GOES-N, the first of the new N series of Geostationary Operational Environmental Satellites. The satellite, which becomes GOES-13 once it reaches its final orbit, joins the U.S. National Oceanic and Atmospheric Administration collection of weather satellites that provide the agency with data for weather forecasts and warnings. The GOES-N series has several improvements over previous GOES satellites. A highly stable pointing platform will allow improved performance from the satellite's sounder-which gathers atmospheric data- and its imager. In addition, the satellite will enable NOAA to improve forecasts and warnings of solar disturbances.

  2. A predictive QoS routing scheme for broadband low Earth orbit satellite networks

    Microsoft Academic Search

    Özgür Erçetin; Srikanth Krishnamurthy; Son Dao; L. Tassiulas

    2000-01-01

    Low Earth orbit satellite networks can augment terrestrial wireless networks to provide global broadband services to users regardless of the users' locations. Delivering QoS guarantees to the users of LEO satellite networks is complicated since the footprints of the LEO satellites move as the satellites traverse their orbits, and thus, causing frequent user handovers between the satellites. Traffic on inter-satellite

  3. Cultures in orbit: Satellite technologies, global media and local practice

    NASA Astrophysics Data System (ADS)

    Parks, Lisa Ann

    Since the launch of Sputnik in 1957, satellite technologies have had a profound impact upon cultures around the world. "Cultures in Orbit" examines these seemingly disembodied, distant relay machines in relation to situated social and cultural processes on earth. Drawing upon a range of materials including NASA and UNESCO documents, international satellite television broadcasts, satellite 'development' projects, documentary and science fiction films, remote sensing images, broadcast news footage, World Wide Web sites, and popular press articles I delineate and analyze a series of satellite mediascapes. "Cultures in Orbit" analyzes uses of satellites for live television relay, surveillance, archaeology and astronomy. The project examines such satellite media as the first live global satellite television program Our World, Elvis' Aloha from Hawaii concert, Aboriginal Australian satellite programs, and Star TV's Asian music videos. In addition, the project explores reconnaissance images of mass graves in Bosnia, archaeological satellite maps of Cleopatra's underwater palace in Egypt, and Hubble Space Telescope images. These case studies are linked by a theoretical discussion of the satellite's involvement in shifting definitions of time, space, vision, knowledge and history. The satellite fosters an aesthetic of global realism predicated on instantaneous transnational connections. It reorders linear chronologies by revealing traces of the ancient past on the earth's surface and by searching in deep space for the "edge of time." On earth, the satellite is used to modernize and develop "primitive" societies. Satellites have produced new electronic spaces of international exchange, but they also generate strategic maps that advance Western political and cultural hegemony. By technologizing human vision, the satellite also extends the epistemologies of the visible, the historical and the real. It allows us to see artifacts and activities on earth from new vantage points; it allows us to read the surface of the earth as a text; and it enables us to see beyond the limits of human civilization and into the alien domain of deep space.

  4. GeoSTAR A Microwave Sounder for Geostationary Bjorn Lambrigtsen (818-354-8932, lambrigtsen@jpl.nasa.gov), William Wilson, Alan Tanner, Todd Gaier

    E-print Network

    Ruf, Christopher

    currently operating on low earth orbiting weather satellites but is intended for deployment in geostationary satellites (GOES- R) planned for the next decade and beyond. GeoSTAR synthesizes a large aperture to measure large and massive dish antenna of a real-aperture system ­ a major advantage of this technology

  5. A census of orbital properties of the M31 satellites

    NASA Astrophysics Data System (ADS)

    Watkins, Laura L.; Evans, N. Wyn; van de Ven, Glenn

    2013-04-01

    We present an analysis of the dynamics of the M31 satellite system. Proper motion data exist for only two of the M31 satellites. We account for this incompleteness in velocity data by a statistical analysis using a combination of the timing argument and phase-space distribution functions. These models provide a good fit to the bulk of the M31 satellites and we offer a table of orbital properties, including period, eccentricity and semimajor axis. This enables us to search for evidence of group infall based on orbital similarity rather than propinquity on the sky. Our results favour an association between Cass II and NGC 185, as the orbital parameters are in close agreement, but not for NGC 185 and NGC 147, which have often been associated in the past. Other possible satellite groupings include the pair And I and And XVII; the pair And IX and And X; and the triple And V, And XXV and NGC 147. And XXII has been claimed as a satellite of M33; we find that they are not moving independently along the same orbit, but cannot determine whether they are orbiting each other or are unrelated. Two satellites, And XII and And XIV, have high line-of-sight velocities, consistent with very recent infall from the edge of the Local Group. They are not well described by our underlying smooth phase-space distribution function, and are reanalysed without priors on their orbital parameters. For And XIV, multiple pericentric passages are possible and improved distance information is needed to draw further conclusions. For And XII, orbits which assume at least one pericentric passage can be ruled out and it must be on its first infall into the M31 system.

  6. LARES successfully launched in orbit: Satellite and mission description

    NASA Astrophysics Data System (ADS)

    Paolozzi, Antonio; Ciufolini, Ignazio

    2013-10-01

    On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically 'frame-dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei-Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation system. The data exploitation phase started immediately after the launch under a new contract between ASI and those universities. Tracking of the satellite is provided by the International Laser Ranging Service. Due to its particular design, LARES is the orbiting object with the highest known mean density in the solar system. In this paper, it is shown that this peculiarity makes it the best proof particle ever manufactured. Design aspects, mission objectives and preliminary data analysis will be also presented.

  7. LARES succesfully launched in orbit: satellite and mission description

    E-print Network

    Antonio Paolozzi; Ignazio Ciufolini

    2013-05-29

    On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically 'frame dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei-Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation system. The data exploitation phase started immediately after the launch under a new contract between ASI and those universities. Tracking of the satellite is provided by the International Laser Ranging Service. Due to its particular design, LARES is the orbiting object with the highest known mean density in the solar system. In this paper, it is shown that this peculiarity makes it the best proof particle ever manufactured. Design aspects, mission objectives and preliminary data analysis will be also presented.

  8. Tether de-orbiting of satellites at end of mission

    NASA Astrophysics Data System (ADS)

    Sanmartin, Juan R.; Sánchez-Torres, Antonio

    2012-07-01

    The accumulation of space debris around the Earth has become critical for Space security. The BETs project, financed by the European Commission through its FP7-Space program, is focusing on preventing generation of new debris by de-orbiting satellites at end of mission. The de-orbiting system considered, involving an electrodynamic bare tape-tether, uses no propellant and no power supply, while generating power for on-board use during de-orbiting. As an example, preliminary results are here presented on a specific orbit/satellite case: 1300 km altitude and 65 degrees inclination, and 500 kg mass. Design tether dimensions are 8 km length, 1.5 cm width, and 0.05 mm thickness; subsystem masses are limited to twice tether mass. Simple calculations, using orbit-averaging, solar mid-cycle phase, and ionospheric and geomagnetic field models, yield 2.6 months time for de-orbiting down to 200 km, with a probability of about 1 percent of debris cutting the tape. References: Sanmartin, J.R., Lorenzini, E.C., and Martinez-Sanchez, M., Electrodynamic Tether Applications and Constraints, J. Space. Rockets 47, 442-456, 2010. Sanmartin, J.R. et al., A universal system to de-orbit satellites at end of life, Journal of Space Technology and Science, to appear.

  9. Cassini orbit determination performance during the first eight orbits of the Saturn satellite tour

    NASA Technical Reports Server (NTRS)

    Antreasian, P. G.; Bordi, J. J.; Criddle, K. E.; Ionasescu, R.; Jacobson, R. A.; Jones, J. B.; MacKenzie, R. A.; Meek, M. C.; Pelletier, F. J.; Roth, D. C.; Roundhill, I. M.; Stauch, J.

    2005-01-01

    From June 2004 through July 2005, the Cassini/Huygens spacecraft has executed nine successful close-targeted encounters by three major satellites of the Saturnian system. Current results show that orbit determination has met design requirements for targeting encounters, Hugens descent, and predicting science instrument pointing for targetd satellite encounters. This paper compares actual target dispersion against, the predicte tour covariance analyses.

  10. TADPOLE satellite. [low cost synchronous orbit satellite to evaluate small mercury bombardment ion thruster applications

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A low cost synchronous orbit satellite to evaluate small mercury bombardment ion thruster applications is described. The ion thrusters provide the satellite with precise north-south and east-west stationkeeping capabilities. In addition, the thrusters are used to unload the reaction wheels used for attitude control and for other purposes described in the report. The proposed satellite is named TADPOLE. (Technology Application Demonstration Program of Low Energy).

  11. An accurate and efficient satellite long-term orbit predictor employing 'fictitious' mean orbital elements

    Microsoft Academic Search

    Charles C. H. Tang

    1988-01-01

    By using Von Zeipel's generating function procedure the perturbing earth gravitational potential is averaged with respect to the fast variable (mean anomaly) and a set of 'fictitous' mean orbital elements which can be used as a long-term satellite orbit predictor is obtained. The set of elements is shown to be a function of the nonlinear square of the second zonal

  12. Orbital decay of satellites crossing an accretion disc

    E-print Network

    V. Karas; L. Subr

    2001-07-13

    Motion of stellar-mass satellites is studied around a massive compact body which is surrounded by a gaseous slab of a stationary accretion disc. The satellites suffer an orbital decay due to hydrodynamical interaction with the disc medium (transitions across the disc, gap opening in the disc, density waves) and gravitational radiation. Arbitrary orbital eccentricities and inclinations are considered, and it is observed how the competing effects depend on the parameters of the model, namely, the mass and compactness of the orbiters, the osculating elements of their trajectories, and surface density of the disc. These effects have a visible impact on the satellites long-term motion, and they can produce observational consequences with respect to galactic central clusters. It is shown that the satellite-disc collisions do not impose serious restrictions on the results of gravitational wave experiments if the disc medium is diluted and the orbiter is compact but they are important in the case of environments with relatively high density. We thus concentrate on application to accretion flows in which the density is not negligible. We discuss the expected quasi-stationary structure of the cluster that is established on sub-parsec scales within the sphere of gravitational influence of the central object. Relevant to this region, we give the power-law slopes defining the radial profile of modified clusters and we show that their values are determined by satellite interaction with the accretion flow rather than their initial distribution.

  13. Precision orbit determination of altimetric satellites

    Microsoft Academic Search

    C. K. Shum; John C. Ries; Byron D. Tapley

    1994-01-01

    The ability to determine accurate global sea level variations is important to both detection and understanding of changes in climate patterns. Sea level variability occurs over a wide spectrum of temporal and spatial scales, and precise global measurements are only recently possible with the advent of spaceborne satellite radar altimetry missions. One of the inherent requirements for accurate determination of

  14. Evaluation and modeling of autonomous attitude thrust control for the Geostation Operational Environmental Satellite (GOES)-8 orbit determination

    NASA Technical Reports Server (NTRS)

    Forcey, W.; Minnie, C. R.; Defazio, R. L.

    1995-01-01

    The Geostationary Operational Environmental Satellite (GOES)-8 experienced a series of orbital perturbations from autonomous attitude control thrusting before perigee raising maneuvers. These perturbations influenced differential correction orbital state solutions determined by the Goddard Space Flight Center (GSFC) Goddard Trajectory Determination System (GTDS). The maneuvers induced significant variations in the converged state vector for solutions using increasingly longer tracking data spans. These solutions were used for planning perigee maneuvers as well as initial estimates for orbit solutions used to evaluate the effectiveness of the perigee raising maneuvers. This paper discusses models for the incorporation of attitude thrust effects into the orbit determination process. Results from definitive attitude solutions are modeled as impulsive thrusts in orbit determination solutions created for GOES-8 mission support. Due to the attitude orientation of GOES-8, analysis results are presented that attempt to absorb the effects of attitude thrusting by including a solution for the coefficient of reflectivity, C(R). Models to represent the attitude maneuvers are tested against orbit determination solutions generated during real-time support of the GOES-8 mission. The modeling techniques discussed in this investigation offer benefits to the remaining missions in the GOES NEXT series. Similar missions with large autonomous attitude control thrusting, such as the Solar and Heliospheric Observatory (SOHO) spacecraft and the INTELSAT series, may also benefit from these results.

  15. Evaluation and modeling of autonomous attitude thrust control for the Geostation Operational Environmental Satellite (GOES)-8 orbit determination

    NASA Astrophysics Data System (ADS)

    Forcey, W.; Minnie, C. R.; Defazio, R. L.

    1995-05-01

    The Geostationary Operational Environmental Satellite (GOES)-8 experienced a series of orbital perturbations from autonomous attitude control thrusting before perigee raising maneuvers. These perturbations influenced differential correction orbital state solutions determined by the Goddard Space Flight Center (GSFC) Goddard Trajectory Determination System (GTDS). The maneuvers induced significant variations in the converged state vector for solutions using increasingly longer tracking data spans. These solutions were used for planning perigee maneuvers as well as initial estimates for orbit solutions used to evaluate the effectiveness of the perigee raising maneuvers. This paper discusses models for the incorporation of attitude thrust effects into the orbit determination process. Results from definitive attitude solutions are modeled as impulsive thrusts in orbit determination solutions created for GOES-8 mission support. Due to the attitude orientation of GOES-8, analysis results are presented that attempt to absorb the effects of attitude thrusting by including a solution for the coefficient of reflectivity, C(R). Models to represent the attitude maneuvers are tested against orbit determination solutions generated during real-time support of the GOES-8 mission. The modeling techniques discussed in this investigation offer benefits to the remaining missions in the GOES NEXT series. Similar missions with large autonomous attitude control thrusting, such as the Solar and Heliospheric Observatory (SOHO) spacecraft and the INTELSAT series, may also benefit from these results.

  16. Orbital rotations of a satellite. Case study: GOCE

    NASA Astrophysics Data System (ADS)

    Baur, O.; Grafarend, E. W.

    Considering a satellite orbit as a space curve in terms of Differential Geometry, we succeeded to merge orbital rotation and curvature/torsion by means of Cartan connection. Here we transform the Frenet frame of reference of the space curve to the Kepler frame of reference ("along track", "cross track", "quasi-radial") of the satellite orbit by means of Meusnier's Lemma. As a case study, we identify the spectrum of orbital rotation frequencies relative to a GOCE satellite configuration. In particular, we identify more than one rotational period. For a moving frame of reference of type Frenet, periods in the range of the time of revolution of the satellite as well as half the time of revolution appear, whereas even periods of a third the revolution time become visible for the Kepler frame of reference. We describe moving frame rotations with respect to the quasi-inertial frame of reference, namely the angular velocities around the base vectors, by means of curvature measures. This allows to calculate frame rotations by geometric orbit information only (GPS track), i.e. apart from gradiometer measurements. Among other things, we identify the angular velocity relative to the second base vector becoming strictly zero in case of the Frenet frame of reference.

  17. GPS single-frequency orbit determination for low Earth orbiting satellites

    Microsoft Academic Search

    Heike Bock; Adrian Jäggi; Rolf Dach; Stefan Schaer; Gerhard Beutler

    2008-01-01

    The determination of high-precision orbits for Low Earth Orbiting (LEO) satellites (e.g., CHAMP, GRACE, MetOp) is based on dual-frequency tracking data from onboard GPS receivers. The two frequencies allow it to eliminate the first order ionosphere effects on the level of the carrier phase measurement noise. Data screening and precise orbit determination (POD) procedures are optimized under the assumption of

  18. GPS single-frequency orbit determination for low Earth orbiting satellites

    Microsoft Academic Search

    H. Bock; A. Jäggi; R. Dach; S. Schaer; G. Beutler

    2009-01-01

    The determination of high-precision orbits for Low Earth Orbiting (LEO) satellites (e.g., CHAMP, GRACE, MetOp-A) is based on dual-frequency tracking data from on-board GPS (Global Positioning System) receivers. The two frequencies allow it to eliminate the first order ionosphere effects. Data screening and precise orbit determination (POD) procedures are optimized under the assumption of the availability of two frequencies.If only

  19. Earth-to-geosynchronous satellite laser beam transmission

    Microsoft Academic Search

    Tadashi Aruga; K. Araki; R. Hayashi; T. Iwabuchi; M. Takahashi; S. Nakamura

    1985-01-01

    Some experimental results for detection of a ground-based laser beacon by a geosynchronous satellite are reported. A 50-cm diam telescope and silicon intensifier tube camera were used for optical observation of the satellite. The transmitted argon laser beam was detected by the visible channel of a radiometer on board the Japanese Geostationary Meteorological Satellite. Two activities, (1) orbit prediction correction

  20. In-Space Transportation for GEO Space Solar Power Satellites

    NASA Technical Reports Server (NTRS)

    Martin, James A.; Donnahue, Benjamin B.; Henley, Mark W.

    1999-01-01

    This report summarizes results of study tasks to evaluate design options for in-space transportation of geostationary Space Solar Power Satellites. Referring to the end-to-end architecture studies performed in 1988, this current activity focuses on transportation of Sun Tower satellite segments from an initial low Earth orbit altitude to a final position in geostationary orbit (GEO; i.e., 35,786 km altitude, circular, equatorial orbit). This report encompasses study activity for In-Space Transportation of GEO Space Solar Power (SSP) Satellites including: 1) assessment of requirements, 2) design of system concepts, 3) comparison of alternative system options, and 4) assessment of potential derivatives.

  1. On-Orbit Calibration of Satellite Gyroscopes

    NASA Technical Reports Server (NTRS)

    Hashmall, Joseph A.; Radomski, Mark; Sedlak, Joseph; Harman, Richard (Technical Monitor)

    2000-01-01

    In order to maneuver satellites accurately from one attitude to another, onboard rate sensing gyroscopes usually must be calibrated after launch. Several algorithms have been used to determine gyro biases, misalignments, and scale factors. This paper describes algorithms that have been used in the past, discusses their advantages and limitations, and describes a new algorithm and the gyro calibration results obtained using this new algorithm. The new algorithm has significant operational advantages in addition to being at least as accurate as other algorithms.

  2. Orbital Resonances during Tidal Heating of Icy Satellites

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Nimmo, F.; Chen, E.

    2008-05-01

    Tides raised by the primary on a synchronized satellite result in heating if the satellite is in an eccentric orbit (Peale et al. 1979). The satellite's orbit, however, is circularized by tidal torques. The corresponding eccentricity damping timescale is usually short compared to the age of the Solar System (a few to several hundred million years for the jovian and saturnian moons). Thus tidal heating scenarios generally require additional mechanisms to maintain sufficient eccentricities, for which orbital mean-motion resonances are natural candidates (e.g. Peale et al. 1979, Showman et al. 1997). The degree of tidal heating depends on the internal structure of the satellite, which in turn depends on the body's thermal evolution, resulting in complicated feedbacks (Ojakangas and Stevenson 1986, Showman et al. 1997, Hussmann and Spohn 2002). We investigate the interaction between mean-motion resonances and satellite thermal evolution, with applications to Saturn's icy moons. Previous studies showed that the competition between resonances and tidal circularization can lead to either an equilibrium state (Yoder and Peale 1981, Meyer and Wisdom 2007) or an oscillation around the equilibrium (Ojakagas and Stevenson 1986). Our preliminary results imply that in some circumstances, however, such an equilibrium does not exist, resulting in large orbital eccentricities and high transient tidal heating rates. We also study the eccentricity evolution near resonant trappings during the heating process, and discover that in many situations, a first-order resonant encounter excites the eccentricities of both orbits simultaneously. We apply our results to Saturn's moon Enceladus and Tethys, together with thermal models for these satellites, to investigate the origin of observed features on their surfaces.

  3. History of On-orbit Satellite Fragmentations (14th Edition)

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.; Stansbery, Eugene; Whitlock, David O.; Abercromby, Kira J.; Shoots, Debra

    2008-01-01

    Since the first serious satellite fragmentation occurred in June 1961 (which instantaneously increased the total Earth satellite population by more than 400%) the issue of space operations within the finite region of space around the Earth has been the subject of increasing interest and concern. The prolific satellite fragmentations of the 1970s and the marked increase in the number of fragmentations in the 1980s served to widen international research into the characteristics and consequences of such events. Continued events in all orbits in later years make definition and historical accounting of those events crucial to future research. Large, manned space stations and the growing number of operational robotic satellites demand a better understanding of the hazards of the dynamic Earth satellite population.

  4. Prototype development of a Geostationary Synthetic Thinned Aperture Radiometer, GeoSTAR

    NASA Technical Reports Server (NTRS)

    Tanner, A. B.; Wilson, W. J.; Kangaslahti, P. P.; Lambrigsten, B. H.; Dinardo, S. J.; Piepmeier, J. R.; Ruf, C. S.; Rogacki, S.; Gross, S. M.; Musko, S.

    2004-01-01

    Preliminary details of a 2-D synthetic aperture radiometer prototype operating from 50 to 55 GHz will be presented. The laboratory prototype is being developed to demonstrate the technologies and system design needed to do millimeter-wave atmospheric soundings with high spatial resolution from Geostationary orbit. The concept is to deploy a large thinned aperture Y-array on a geostationary satellite, and to use aperture synthesis to obtain images of the Earth without the need for a large mechanically scanned antenna. The laboratory prototype consists of a Y-array of 24 horn antennas, MMIC receivers, and a digital cross-correlation sub-system.

  5. Orbital performance of communication satellite microwave power amplifiers (MPAs)

    Microsoft Academic Search

    R. Strauss

    1993-01-01

    This paper presents background data on the performance of microwave power amplifiers (MPAs) used as transmitters in currently operating commercial communication satellites. Specifically aspects of two competing MPA types are discussed. These are well known TWTA (travelling wave tube amplifier) and the SSPA (solid state power amplifier). Extensive in-orbit data has been collected from over 2000 MPAs in 1991 and

  6. Low earth orbit satellite based communication systems — Research opportunities

    Microsoft Academic Search

    Bezalel Gavish

    1997-01-01

    Telecommunication systems are undergoing revolutionary changes that are transforming society, changing the way in which industrial and service organizations operate, and are having a profound effect on the daily life of individuals. Low earth orbit satellite (LEOS) based communication systems are a new and exciting endeavor in reshaping the global communication network and the services that it provides. Huge investments

  7. An efficient algorithm for orbital evolution of artificial satellite

    Microsoft Academic Search

    Yehia A. Abdel-aziz; F. A. Abd El-salam

    2007-01-01

    Searching for an accurate model to evaluate the orbital position of the operating satellites and space debris is very important at the time being. This is actually to design different maneuvering schemes to avoid catastrophic consequences of collision. In the present paper a second order theory of perturbations (in the sense of the Hori–Lie perturbation method) is developed. The most

  8. Analytical study of the Earth's shadowing effects on satellite orbits

    Microsoft Academic Search

    S. Ferraz Mello

    1972-01-01

    In this paper a new mathematical model is proposed for the study of the effects of the direct solar radiation pressure on the orbit of an artificial Earth satellite. The equations for the first order effects become canonical when a different definition for the orders of magnitude is adopted. This enables us the utilization of the method of Von Zeipel

  9. Anisotropy in the Distribution of Satellite Galaxy Orbits

    E-print Network

    Alexander Knebe; Stuart P. D. Gill; Brad K. Gibson; Geraint F. Lewis; Rodrigo A. Ibata; Michael A. Dopita

    2003-11-10

    Nearby clusters such as Virgo and Coma possess galaxy distributions which tend to be aligned with the principal axis of the cluster itself. This has also been confirmed by a recent statistical analysis of some 300 Abell clusters where the effect has been linked to the dynamical state of the cluster. Moreover, the orbits of satellite galaxies in galactic systems like our own Milky Way also demonstrate a high degree of anisotropy - the so-called Holmberg effect, the origin of which has been the subject of debate for more than 30 years. This study presents the analysis of cosmological simulations focusing on the orbits of satellite galaxies within dark matter halos. The apocentres of the orbits of these satellites are preferentially found within a cone of opening angle ~40 around the major axis of the host halo, in accordance with the observed anisotropy found in galaxy clusters. We do, however, note that a link to the dynamical age of the cluster is not well established as both our oldest dark matter halos do show a clear anisotropy signal. Further analysis connects this distribution to the infall pattern of satellites along the filaments: the orbits are determined rather by the environment of the host halo than some "dynamical selection" during their life within the host's virial radius.

  10. Modified multirevolution integration methods for satellite orbit computation

    Microsoft Academic Search

    O. F. Graf; D. G. Bettis

    1975-01-01

    Multirevolution methods allow for the computation of satellite orbits in steps spanning many revolutions. The methods previously discussed in the literature are based on polynomial approximations, and as a result they will integrate exactly (excluding round-off errors) polynomial functions of a discrete independent variable. Modified methods are derived that will integrate exactly products of linear and periodic functions. Numerical examples

  11. An Earth Orbiting Satellite Service and Repair Facility

    NASA Technical Reports Server (NTRS)

    Berndt, Andrew; Cardoza, Mike; Chen, John; Daley, Gunter; Frizzell, Andy; Linton, Richard; Rast, Wayne

    1989-01-01

    A conceptual design was produced for the Geosynchronous Satellite Servicing Platform (GSSP), an orbital facility capable of repairing and servicing satellites in geosynchronous orbit. The GSSP is a man-tended platform, which consists of a habitation module, operations module, service bay and truss assembly. This design review includes an analysis of life support systems, thermal and power requirements, robotic and automated systems, control methods and navigation, and communications systems. The GSSP will utilize existing technology available at the time of construction, focusing mainly on modifying and integrating existing systems. The entire facility, along with two satellite retrieval vehicles (SRV), will be placed in geosynchronous orbit by the Advanced Launch System. The SRV will be used to ferry satellites to and from the GSSP. Technicians will be transferred from Earth to the GSSP and back in an Apollo-derived Crew Transfer Capsule (CTC). These missions will use advanced telerobotic equipment to inspect and service satellites. Four of these missions are tentatively scheduled per year. At this rate, the GSSP will service over 650 satelites during the projected 25 year lifespan.

  12. Geostationary Earth Radiation Budget (GERB) data

    NASA Astrophysics Data System (ADS)

    Russell, J. E.; Harries, J. E.

    The Geostationary Earth Radiation Budget GERB instrument on METEOSAT 8 is designed to provide an accurate measure of the reflected solar and emitted thermal energy from a geostationary orbit GERB data products consist of broadband radiances and fluxes every 15 minutes for the whole METEOSAT 8 region The GERB data provide the first broadband measurements of the radiation budget at such high time resolution and therefore offer new opportunities to study quickly varying climate processes such as cloud and aerosol The first GERB was launched in 2002 on the MSG 1 satellite which was declared operational and renamedMET EOSAT 8 in February 2004 By the time of this conference the first release of GERB data will have been made and the commissioning of a second GERB instrument on the MSG 2 satellite will be underway Here we detail the GERB products and present the validation results and data quality assessment for the released data and detail our plans for future products We will also present the initial results from the commissioning of the second GERB instrument and compare observations from the two GERBs

  13. Handbook on satellite communications and broadcasting

    Microsoft Academic Search

    G. B. Askinazi; V. L. Bykov; G. V. Vodopianov; M. N. D'Iachkova; L. Ia. Kantor; A. M. Model; A. M. Pokras; V. V. Timofeev; V. M. Tsirlin; I. S. Tsirlin

    1983-01-01

    Principles underlying the design and operation of satellite communications systems (SCSs) are reviewed with emphasis on multiple-access techniques. Particular consideration is given to the quality characteristics of CSCs, the frequency ranges assigned to SCSs, an energy analysis of satellite lines, EMC aspects, and the effective utilization of the geostationary orbit. Also examined are the design of earth-station equipment, waveguides and

  14. Planning satellite communication services and spectrum-orbit utilization

    NASA Technical Reports Server (NTRS)

    Sawitz, P. H.

    1982-01-01

    The relationship between approaches to planning satellite communication services and spectrum-orbit utilization is considered, with emphasis on the fixed-satellite and the broadcasting-satellite services. It is noted that there are several possible approaches to planning space services, differing principally in the rigidity with which technical parameters are prescribed, in the time for which a plan remains in force, and in the procedures adopted for implementation and modifications. With some planning approaches, spectrum-orbit utilization is fixed at the time the plan is made. Others provide for greater flexibility by making it possible to postpone some decisions on technical parameters. In addition, the two political questions of what is equitable access and how it can be guaranteed in practice play an important role.

  15. Observations of orbital debris and satellites in Slovak Republic

    NASA Astrophysics Data System (ADS)

    Silha, Jiri; Toth, Juraj

    There are many accidental optically tracked artificial objects during observations at Astronom-ical and Geophysical Observatory FMPI CU, Modra, Slovak Republic (AGO). Those objects are usually orbital debris or satellites. A tool to identify such a type of objects was necessary to create. Our software is called SatEph and is used to identify tracked artificial objects and to compute their orbital elements. SatEph is based on analytic propagation model SGP4 and TLE data. Program is still under development and in the near future it will be a part of software for automated search telescope for small near Earth asteroids at AGO. We present orbital debris observation simulation for the new optical searching system. Unlike other aster-oids searching systems (Catalina Sky Survey, LINEAR, Spacewatch etc.) our system should be capable to detect small asteroids in close vicinity of the Earth (smaller then Lunar distance) with high angular speed. The limiting magnitude of observable objects is about +16 magnitude and the pixel scale is 4,6 arcsec/px. This allows us to detect man made objects as well. We studied how many satellites and orbital debris with known orbital elements are able to track per given observing night. We also studied frequency detection of tracked object during one night. The searching system field of view will be 4.4 x 4.4 square degrees and the system will search more then 2000 square degrees per night. Exposure time for every single CCD shot is set to 30 seconds. We found out, there is possible to track from 250 to 450 objects (mostly with geosynchronous orbits) per one night in dependence on given day of the year. More then 200 objects have at least 3 astrometric positions per one night, which can be useful for orbit determination process. The tracked objects are mostly satellites and rocket bodies, which have different orbits, from low Earth orbit to geosynchronous Earth orbit. Data of orbital debris astrometric positions will be offered for national space agencies and used for our own orbit determination. Those data could be useful for orbital elements updating of catalogue, or non catalogue artificial objects.

  16. Benefits Derived From Laser Ranging Measurements for Orbit Determination of the GPS Satellite Orbit

    NASA Technical Reports Server (NTRS)

    Welch, Bryan W.

    2007-01-01

    While navigation systems for the determination of the orbit of the Global Position System (GPS) have proven to be very effective, the current research is examining methods to lower the error in the GPS satellite ephemerides below their current level. Two GPS satellites that are currently in orbit carry retro-reflectors onboard. One notion to reduce the error in the satellite ephemerides is to utilize the retro-reflectors via laser ranging measurements taken from multiple Earth ground stations. Analysis has been performed to determine the level of reduction in the semi-major axis covariance of the GPS satellites, when laser ranging measurements are supplemented to the radiometric station keeping, which the satellites undergo. Six ground tracking systems are studied to estimate the performance of the satellite. The first system is the baseline current system approach which provides pseudo-range and integrated Doppler measurements from six ground stations. The remaining five ground tracking systems utilize all measurements from the current system and laser ranging measurements from the additional ground stations utilized within those systems. Station locations for the additional ground sites were taken from a listing of laser ranging ground stations from the International Laser Ranging Service. Results show reductions in state covariance estimates when utilizing laser ranging measurements to solve for the satellite s position component of the state vector. Results also show dependency on the number of ground stations providing laser ranging measurements, orientation of the satellite to the ground stations, and the initial covariance of the satellite's state vector.

  17. Quasi-satellite Orbits in the Context of Coorbital Dynamics

    NASA Astrophysics Data System (ADS)

    Sidorenko, Vladislav; Artemyev, A.; Neishtadt, A.; Zelenyi, L.

    2013-05-01

    Abstract (2,250 Maximum Characters): The investigations on long-term evolution of asteroid’s orbits are crucial to understanding the route through which the present configuration of the Solar system came to be. The so-called coorbiting asteroids (which share their orbits with major planets) attract the special attention in this connection: are they the primordial remnants of the building blocks of the corresponding major planet or are they the "migrants" from the other parts of the Solar system? The most well known examples of co-orbits in natural objects are provided by Trojan groups of asteroids and by asteroids moving in horseshoe orbits. These asteroids are precluded from having relatively close encounters with their host planets. However, there exists another class of coorbiting objects in which the opposite is true: they remain very near to the host planet eternally or, at least, for long enough time. Since typically they never enter the planet’s Hill sphere, they cannot be considered as satellites in the usual sense of the word. In order to emphasize this specific they are called quasi-satellites (QS). We explore the properties of QS-orbits under the scope of the restricted spatial circular three-body problem. Via double numerical averaging, we construct evolutionary equations which describe the long-term behaviour of the orbital elements of an asteroid. Special attention is paid at possible transitions between the motion in a QS-orbit and that in another type of orbit available in the 1:1 mean motion resonance. To illustrate the typical rates of the orbital elements's secular evolution, the dynamics of the near-Earth asteroid 2004GU9 was studied. This asteroid will keep describing a QS-orbit for the next several hundreds of years. This work was supported by the grant of the Russian Academy of Sciences Presidium Program 22: "Fundamental problems of research and exploration of the Solar system".

  18. Orbital simulations of satellite escape/capture and the origin of satellites such as Triton

    NASA Technical Reports Server (NTRS)

    Benner, Lance A. M.; Mckinnon, William B.

    1993-01-01

    We investigate satellite escape/capture in the context of the restricted, circular three body problem as applied to the Sun, Neptune, and Triton. We have computed a large number of coplanar prograde and retrograde orbital simulations over a range of initial distances and velocities. The satellite starts at superior conjunction within approximately 2 Hill radii of Neptune and has a velocity orthogonal to the Sun-planet line. Orbits with these initial conditions can be reflected with respect to time, so an escape is simply the reverse of a capture. We numerically integrate the equations of motion to compute the satellite's position until it escapes, collides with Neptune, or after 100 planetary years fails to escape, when computations cease. The initial distance x and velocity v in the restricted problem uniquely define the Jacobi constant C, a conserved energy-like quantity. Plots of the simulation outcomes in the prograde and retrograde C, x phase spaces reveal distinct zones in which temporary satellites approach the planet closely enough that permanent capture can be effected by gas drag with a protoplanetary nebula or by collision with a pre-existing satellite. Single and double close-flybys constitute the most common possible capture orbits. Long term multiple flyby orbits occur near the stability limits between bound and unbound orbits, and are more common among retrograde captures.

  19. Satellite Motion Effects on Current Collection in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Zhang, T. X.; Hwang, K. S.; Wu, S. T.; Stone, N. H.; Chang, C. L.; Drobot, A.; Wright, K. H., Jr.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Results from the Tethered Satellite System (TSS) missions unambiguously show that the electrodynamic tether system produced 2 to 3 times the predicted current levels in the tether. The pre-mission predictions were based on the well-known Parker-Murphy (PM) model, which describes the collection of current by an electrically biased satellite in the ionospheric plasma. How the TSS satellite was able to collect 2-3 times the PM current has remained an open question. In the present study, self-consistent potential and motional effects are introduced into the Thompson and Dobrowolny sheath models. As a result, the magnetic field aligned sheath-an essential variable in determining current collection by a satellite-is derived and is shown to be explicitly velocity dependent. The orientation of the satellite's orbital motion relative to the geomagnetic field is also considered in the derivation and a velocity dependent expression for the collected current is obtained. The resulting model provides a realistic treatment of current collection by a satellite in low earth orbit. Moreover, the predictions, using the appropriate parameters for TSS, are in good agreement with the tether currents measured during the TSS-1R mission.

  20. The Geostationary Earth Radiation Budget Project.

    NASA Astrophysics Data System (ADS)

    Harries, J. E.; Russell, J. E.; Hanafin, J. A.; Brindley, H.; Futyan, J.; Rufus, J.; Kellock, S.; Matthews, G.; Wrigley, R.; Last, A.; Mueller, J.; Mossavati, R.; Ashmall, J.; Sawyer, E.; Parker, D.; Caldwell, M.; Allan, P. M.; Smith, A.; Bates, M. J.; Coan, B.; Stewart, B. C.; Lepine, D. R.; Cornwall, L. A.; Corney, D. R.; Ricketts, M. J.; Drummond, D.; Smart, D.; Cutler, R.; Dewitte, S.; Clerbaux, N.; Gonzalez, L.; Ipe, A.; Bertrand, C.; Joukoff, A.; Crommelynck, D.; Nelms, N.; Llewellyn-Jones, D. T.; Butcher, G.; Smith, G. L.; Szewczyk, Z. P.; Mlynczak, P. E.; Slingo, A.; Allan, R. P.; Ringer, M. A.

    2005-07-01

    This paper reports on a new satellite sensor, the Geostationary Earth Radiation Budget (GERB) experiment. GERB is designed to make the first measurements of the Earth's radiation budget from geostationary orbit. Measurements at high absolute accuracy of the reflected sunlight from the Earth, and the thermal radiation emitted by the Earth are made every 15 min, with a spatial resolution at the subsatellite point of 44.6 km (north south) by 39.3 km (east west). With knowledge of the incoming solar constant, this gives the primary forcing and response components of the top-of-atmosphere radiation. The first GERB instrument is an instrument of opportunity on Meteosat-8, a new spin-stabilized spacecraft platform also carrying the Spinning Enhanced Visible and Infrared (SEVIRI) sensor, which is currently positioned over the equator at 3.5°W. This overview of the project includes a description of the instrument design and its preflight and in-flight calibration. An evaluation of the instrument performance after its first year in orbit, including comparisons with data from the Clouds and the Earth's Radiant Energy System (CERES) satellite sensors and with output from numerical models, are also presented. After a brief summary of the data processing system and data products, some of the scientific studies that are being undertaken using these early data are described. This marks the beginning of a decade or more of observations from GERB, as subsequent models will fly on each of the four Meteosat Second Generation satellites.


  1. Relative Equilibria of a Rigid Satellite in a Circular Keplerian Orbit

    E-print Network

    Hall, Christopher D.

    Relative Equilibria of a Rigid Satellite in a Circular Keplerian Orbit Jeffrey A. Beck are particularly interested in the application to an artificial satellite orbiting the Earth. Hence, we further with the body appearing stationary in an orbiting reference frame. Artificial satellites de- signed to remain

  2. Geostationary Antenna for Disturbance-Free Laser Interferometry (GADFLI)

    E-print Network

    Sean T. McWilliams

    2011-11-16

    We present a mission concept, the Geostationary Antenna for Disturbance-Free Laser Interferometry (GADFLI), for a space-based gravitational-wave interferometer consisting of three satellites in geostationary orbit around the Earth. Compared to the nominal design of the Laser Interferometer Space Antenna (LISA), this concept has the advantages of significantly decreased requirements on the telescope size and laser power, decreased launch mass, substantially improved shot noise resulting from the shorter 73000 km armlengths, simplified and less expensive communications, and an overall lower cost which we (roughly) estimate at $1.2B. GADFLI preserves much of the science of LISA, particularly the observation of massive black-hole binary coalescences, although the SNR is diminished for all masses in the potential designs we consider.

  3. Geostationary Antenna for Disturbance-Free Laser Interferometry (GADFLI)

    E-print Network

    McWilliams, Sean T

    2011-01-01

    We present a mission concept, the Geostationary Antenna for Disturbance-Free Laser Interferometry (GADFLI), for a space-based gravitational-wave interferometer consisting of three satellites in geostationary orbit around the Earth. Compared to the nominal design of the Laser Interferometer Space Antenna (LISA), this concept has the advantages of significantly decreased requirements on the telescope size and laser power, decreased launch mass, substantially improved shot noise resulting from the shorter 73000 km armlengths, simplified and less expensive communications, and an overall lower cost which we (roughly) estimate at $1.2B. GADFLI preserves much of the science of LISA, particularly the observation of massive black-hole binary coalescences, although the SNR is diminished for all masses in the potential designs we consider.

  4. Analysis of Satellite and Sub-Orbital Measurements

    NASA Technical Reports Server (NTRS)

    Gleason, James (Technical Monitor); Martin, Randall V.

    2004-01-01

    The objective of this project is to support the INTEX aircraft mission by developing experience in the integrated analysis of existing sub-orbital observations and satellite observations with numerical models. Specific tasks include providing guidance to INTEX by identifying discrepancies in satellite observations with (1) in situ measurements, (2) bottom-up emission inventories of nitrogen oxides and volatile organic compounds, and (3) model calculations of the export of pollution from North America to the global atmosphere. An important focus area is developing and improving bottom-up emission inventories by combining top-down and bottom-up information.

  5. A retrospective analysis of the Shinmoedake (Japan) eruption of 26-27 January 2011 by means of Japanese geostationary satellite data

    NASA Astrophysics Data System (ADS)

    Marchese, F.; Falconieri, A.; Pergola, N.; Tramutoli, V.

    2014-01-01

    During the sub-plinian eruptions of Mt. Shinmoedake (Japan) on 26-27 January 2011 a significant amount of ash was emitted into the atmosphere, destroying thousands of hectares of farm land, causing air traffic disruption, and forcing the closure of four railroad lines located around the volcano. In this work, a retrospective analysis of these eruptive events is presented, exploiting the high temporal resolution of the Japanese Multi-functional Transport Satellites (MTSAT) data to study thermal volcanic activity, to identify and track volcanic ash, and to determine the cloud-top height, inferring information about eruption features and space-time evolution. We show that a strong and sudden increase in the thermal signal occurred at Mt. Shinmoedake as a consequence of above mentioned eruptive events, generating hot spots timely detected by the RSTVOLC algorithm for the first time implemented here on data provided by geostationary satellites. This study also shows that the emitted ash plume, identified by means of the RSTASH algorithm, strongly fluctuated in altitude, reaching a maximum height around 7.4 km above sea level, in agreement with information provided by the Tokyo VAAC. The plume heights derived in this work, by implementing the widely accepted cloud-top temperature method, appear also compatible with the values provided by independent weather radar measurements, with the main differences characterizing the third sub-plinian event that occurred in the afternoon of 27 January. The estimates of discharge rate, the temporal trend of ash affected areas, and the results of thermal monitoring reported in this work seem to indicate that the third sub-plinian event was the least intense. In spite of some limitations, this study confirms the potential of Japanese geostationary satellites in effectively monitoring volcanoes located in the West Pacific region, providing continuous information also about such critical parameters of ash clouds as the plume height. Such information is useful not only for driving numerical models, forecasting ash dispersion into the atmosphere, but also for characterizing eruption features and dynamics.

  6. Correction of sub-pixel topographical effects on land surface albedo retrieved from geostationary satellite (FengYun-2D) observations

    NASA Astrophysics Data System (ADS)

    Roupioz, L.; Jia, L.; Nerry, F.; Menenti, M.

    2014-03-01

    The Qinghai-Tibetan Plateau is characterised by a very strong relief which affects albedo retrieval from satellite data. The objective of this study is to highlight the effects of sub-pixel topography and to account for those effects when retrieving land surface albedo from geostationary satellite FengYun-2D (FY-2D) data with 1.25km spatial resolution using the high spatial resolution (30 m) data of the Digital Elevation Model (DEM) from ASTER. The methodology integrates the effects of sub-pixel topography on the estimation of the total irradiance received at the surface, allowing the computation of the topographically corrected surface reflectance. Furthermore, surface albedo is estimated by applying the parametric BRDF (Bidirectional Reflectance Distribution Function) model called RPV (Rahman-Pinty-Verstraete) to the terrain corrected surface reflectance. The results, evaluated against ground measurements collected over several experimental sites on the Qinghai-Tibetan Plateau, document the advantage of integrating the sub-pixel topography effects in the land surface reflectance at 1km resolution to estimate the land surface albedo. The results obtained after using sub-pixel topographic correction are compared with the ones obtained after using pixel level topographic correction. The preliminary results imply that, in highly rugged terrain, the sub-pixel topography correction method gives more accurate results. The pixel level correction tends to overestimate surface albedo.

  7. Shuttle orbiter - IUS/DSP satellite interface contamination study

    NASA Technical Reports Server (NTRS)

    Rantanen, R. O.; Strange, D. A.

    1978-01-01

    The results of a contamination analysis on the Defense Support Program (DSP) satellite during launch and deployment by the Space Transportation System (STS) are presented. Predicted contaminant deposition was also included on critical DSP surfaces during the period soon after launch when the DSP is in the shuttle orbiter bay with the doors closed, the bay doors open, and during initial deployment. Additionally, a six sided box was placed at the spacecraft position to obtain directional contaminant flux information for a general payload while in the bay and during deployment. The analysis included contamination sources from the shuttle orbiter, IUS and cradle, the DSP sensor and the DSP support package.

  8. GNSS Satellite Orbit Validation Using Satellite Laser Ranging O. Montenbruck (1), P. Steigenberger (2), G. Kirchner (3)

    E-print Network

    Heiz, Ulrich

    02-09 GNSS Satellite Orbit Validation Using Satellite Laser Ranging O. Montenbruck (1), P satellites of the new constellations (i.e. Galileo, BeiDou, QZSS and IRNSS) are equipped with laser ranging.montenbruck@dlr.de Abstract. With a total of four new regional and global navigation satellite systems that have launched

  9. Heat Transfer -1 A satellite in space orbits the sun. The satellite can be approximated as a flat plate with

    E-print Network

    Virginia Tech

    Heat Transfer - 1 A satellite in space orbits the sun. The satellite can be approximated as a flat the sun is a blackbody with radius and surface temperature given below. (25 %) (b) The satellite perpendicular to the radiation coming from the sun. Assuming the satellite is at a uniform temperature, find

  10. Revisiting elliptical satellite orbits to enhance the O3b constellation

    E-print Network

    Wood, Lloyd

    coverage of selected high-latitude locations, using a minimal number of satellites. 2.MOLNYA AND TUNDRA ELLIPTICAL ORBITS Molniya and Tundra orbits were exploited by the Soviet Union, for television broadcast North America. Tundra orbits, who

  11. Stability of the Galilean satellites in deep orbital resonance

    NASA Astrophysics Data System (ADS)

    Greenberg, R.

    1985-04-01

    The Galilean satellites are locked in the Laplace resonance, which is responsible for forcing their significant orbital eccentricites. The eccentricites in turn result in tidal energy dissipation within the satellites that is responsible for the great thermal activity on Io, including both volcanism observed by Voyager and heat flux measured from Earth. The resonance results from the nearly 2:1 commensurability of orbital periods (or equivalently of mean motions) taken by pairs. These geometrical relations enhance the mutual gravitational effects. Yoder pointed out that tides raised on Io tend to drive the system out of resonance (toward greater nu and correspondingly smaller eccentricities) while tides raised on Jupiter tend to drive the system towards deeper resonance (smaller nu and larger forced eccentricities). The possible behavior of the system in deep resonance is investigated.

  12. Orbital perturbations of the Galilean satellites during planetary encounters

    SciTech Connect

    Deienno, Rogerio; Nesvorný, David [Southwest Research Institute, Boulder, CO (United States); Vokrouhlický, David [Institute of Astronomy, Charles University, Prague (Czech Republic); Yokoyama, Tadashi, E-mail: rogerio.deienno@gmail.com [Universidade Estadual Paulista, Rio Claro, SP (Brazil)

    2014-08-01

    The Nice model of the dynamical instability and migration of the giant planets can explain many properties of the present solar system, and can be used to constrain its early architecture. In the jumping-Jupiter version of the Nice model, required from the terrestrial planet constraint and dynamical structure of the asteroid belt, Jupiter has encounters with an ice giant. Here, we study the survival of the Galilean satellites in the jumping-Jupiter model. This is an important concern because the ice-giant encounters, if deep enough, could dynamically perturb the orbits of the Galilean satellites and lead to implausible results. We performed numerical integrations where we tracked the effect of planetary encounters on the Galilean moons. We considered three instability cases from Nesvorný and Morbidelli that differed in the number and distribution of encounters. We found that in one case, where the number of close encounters was relatively small, the Galilean satellite orbits were not significantly affected. In the other two, the orbital eccentricities of all moons were excited by encounters, Callisto's semimajor axis changed, and, in a large fraction of trials, the Laplace resonance of the inner three moons was disrupted. The subsequent evolution by tides damps eccentricities and can recapture the moons in the Laplace resonance. A more important constraint is represented by the orbital inclinations of the moons, which can be excited during the encounters and not appreciably damped by tides. We find that one instability case taken from Nesvorný and Morbidelli clearly does not meet this constraint. This shows how the regular satellites of Jupiter can be used to set limits on the properties of encounters in the jumping-Jupiter model, and help us to better understand how the early solar system evolved.

  13. Orbital Perturbations of the Galilean Satellites during Planetary Encounters

    NASA Astrophysics Data System (ADS)

    Deienno, Rogerio; Nesvorný, David; Vokrouhlický, David; Yokoyama, Tadashi

    2014-08-01

    The Nice model of the dynamical instability and migration of the giant planets can explain many properties of the present solar system, and can be used to constrain its early architecture. In the jumping-Jupiter version of the Nice model, required from the terrestrial planet constraint and dynamical structure of the asteroid belt, Jupiter has encounters with an ice giant. Here, we study the survival of the Galilean satellites in the jumping-Jupiter model. This is an important concern because the ice-giant encounters, if deep enough, could dynamically perturb the orbits of the Galilean satellites and lead to implausible results. We performed numerical integrations where we tracked the effect of planetary encounters on the Galilean moons. We considered three instability cases from Nesvorný & Morbidelli that differed in the number and distribution of encounters. We found that in one case, where the number of close encounters was relatively small, the Galilean satellite orbits were not significantly affected. In the other two, the orbital eccentricities of all moons were excited by encounters, Callisto's semimajor axis changed, and, in a large fraction of trials, the Laplace resonance of the inner three moons was disrupted. The subsequent evolution by tides damps eccentricities and can recapture the moons in the Laplace resonance. A more important constraint is represented by the orbital inclinations of the moons, which can be excited during the encounters and not appreciably damped by tides. We find that one instability case taken from Nesvorný & Morbidelli clearly does not meet this constraint. This shows how the regular satellites of Jupiter can be used to set limits on the properties of encounters in the jumping-Jupiter model, and help us to better understand how the early solar system evolved.

  14. Efficient satellite orbit modelling using pseudo-stochastic parameters

    Microsoft Academic Search

    G. Beutler; A. Jäggi; U. Hugentobler; L. Mervart

    2006-01-01

    If the force field acting on an artificial Earth satellite is not known a priori with sufficient accuracy to represent its observations on their accuracy level, one may introduce so-called pseudo-stochastic parameters into an orbit determination process, e.g. instantaneous velocity changes at user-defined epochs or piecewise constant accelerations in user-defined adjacent time subintervals or piecewise linear and continuous accelerations in

  15. Anisotropy in the Distribution of Satellite Galaxy Orbits

    Microsoft Academic Search

    Alexander Knebe; Stuart P. D. Gill; Brad K. Gibson; Geraint F. Lewis; Rodrigo A. Ibata; Michael A. Dopita

    2003-01-01

    Nearby clusters such as Virgo and Coma possess galaxy distributions which\\u000atend to be aligned with the principal axis of the cluster itself. This has also\\u000abeen confirmed by a recent statistical analysis of some 300 Abell clusters\\u000awhere the effect has been linked to the dynamical state of the cluster.\\u000aMoreover, the orbits of satellite galaxies in galactic systems

  16. Inference of cirrus cloud properties using satellite-observed visible and infrared radiances. Part II: verification of theoretical cirrus radiative properties

    Microsoft Academic Search

    Patrick Minnis; Patrick W. Heck; David F. Young

    1993-01-01

    A methodology is developed to apply a parameterization of radiative transfer calculations to satellite analyses of cirrus clouds. Cloud heights and optical depths are derived from visible and infrared window measurements taken during the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE). Geostationary satellite retrievals are compared to lidar-derived cloud heights and retrievals from a polar-orbiting satellite taken

  17. Cloud-top Height Esimation Method by Geostationary Satellite Split-Window Measurements Trained with CALIPSO and CloudSat data

    NASA Astrophysics Data System (ADS)

    Nishi, Noriyuki; Hamada, Atsushi; Hirose, Hitoshi

    2015-04-01

    We released a database of cloud top height and visible optical thickness (CTOP) with one-hour resolution over the tropical western Pacific and Maritime Continent, by using infrared split-window data of the geostationary satellites (MTSAT) (http://database.rish.kyoto-u.ac.jp/arch/ctop/). We made lookup tables for estimating cloud top height only with geostationary infrared observations by comparing them with the direct cloud observation by CloudSat (Hamada and Nishi, 2010, JAMC). We picked out the same-time observations by MTSAT and CloudSat and regressed the cloud top height observation of CloudSat back onto 11 micro m brightness temperature (Tb) and the difference between the 11 micro m Tb and 12 micro m Tb of MTSAT. The database contains digital data and quick look images from Jul 2005 to real time and the area in 85E-155W (MTSAT2) and 20S-20N. Though the CTOP dataset is particularly useful for the upper tropospheric clouds, it has one serious problem. The cloud radar onboard CloudSat cannot well detect the optically thin cirrus clouds composed of small ice crystals and misses a certain part of cirriform clouds in the upper troposphere. In order to overcome this weakness, we are now making next version of the CTOP by using the lidar data (CALIOP) onboard CALIPSO satellite. One problem on the use of lidar observation is that they observe very thin cirrus formed around the tropopause. The main purpose of CTOP dataset is to provide the top height of clouds that originate from cloud clusters including cumulonimbus and nimbostratus, not of in-situ cirrus clouds formed near the tropopause. To exclude the very thin tropopause cirrus, we define cloud-top height of CALIOP observation as the height at which the optical depth accumulated from the cloud top is 0.2, instead of the CALIOP cloud top itself. With this criterion we can succeed in estimating the top height of cirruiform clouds, but it has another problem for thick clouds like cumulonimbus. For such clouds, the height of accumulated optical depth 0.2 is considerably lower than the real cloud top, possibly due to rather small number of large cloud particles near the top. Therefore, the estimation using CloudSat data is closer to the real top for the thick clouds, while that using CALIOP data is closer for cirriform clouds. So we are now making a lookup table with using both CloudSat and CALIPSO data to estimate cloud-top heights both for thick and thin clouds seamlessly.

  18. Evaluation of IGS Orbits with Satellite Laser Ranging

    NASA Technical Reports Server (NTRS)

    Watkins, M. M.; Bar-Sever, Y. E.; Yuan, D. N.

    1996-01-01

    The accuracy with which orbits for the Global Positioning System (GPS) spacecraft, can be computed directly affects the accuracy of the resulting site coordinates and polar motion. Several groups routinely analyze GPS ground tracking data to compute precise orbits and terrestrial reference frame solutions. In this paper, we infer the accuracy of the orbits of two of the GPS satellites by comparing to independent laser ranges of subcentimeter accuracy obtained by a small but reasonably well distributed network of tracking sites. We find that all seven International GPS Service for Geodynamics (IGS) analysis centers achieve range residual root mean square (rms) errors at or below the 100 mm level. The best orbit solutions, from JPL, CODE, and the IGS combined product, yield a residual rms of about 50 mm. These residuals are consistent with three dimensional orbit errors of less than 150 mm. Estimating yaw rates for the spacecraft during shadow events, and using these estimates to compute the laser residual, significantly improves the fit. A small mean residual value of -15 to -30 mm seems to exist for most centers and laser sites which is not fully explained at present, but may be due to uncertainties in the corrections to the laser data, such as the reflector to spacecraft center of mass vector or small reference frame differences between the SLR sites and the GPS orbits.

  19. Progress in developing a geostationary AMSU

    NASA Astrophysics Data System (ADS)

    Lambrigtsen, Bjorn

    2009-09-01

    The "Precipitation and All-weather Temperature and Humidity" (PATH) mission is one of the 15 NASA "decadalsurvey" missions recommended by the U.S. National Research Council in 2007 and will implement the first microwave sounder in geostationary orbit. This is possible with a new sensor being developed at the Jet Propulsion Laboratory, the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR). Adequate spatial resolution is achieved by using aperture synthesis instead of a large parabolic reflector as is used in conventional systems. A proof-of-concept prototype was developed at JPL in 2005 under the NASA Instrument Incubator Program and used to demonstrate that this new concept works well at sounding frequencies. Another IIP effort is now under way to advance key technology required for a full space system. The maturity of the concept and technology is now such that mission development could be initiated in 2010-11. The possibility of flying GeoSTAR as an "instrument of opportunity" on NOAA's new series of "GOES-R" geostationary weather satellites is being actively pursued. Other low-cost options are under study as well. PATH/GeoSTAR will provide a number of measurements that are key in monitoring and predicting hurricanes and severe storms - including hemispheric 3-dimensional temperature, humidity and cloud liquid water fields, rain rates and rain totals, tropospheric wind vectors, sea surface temperature, and parameters associated with deep convection and atmospheric instability - everywhere and all the time, even in the presence of clouds - and will also provide key measurements related to climate research.

  20. Precise orbit determination of a maneuvered GEO satellite using CAPS ranging data

    Microsoft Academic Search

    Yong Huang; Xiaogong Hu; Cheng Huang; Qiangwen Yang; Wenhai Jiao

    2009-01-01

    Wheel-off-loadings and orbital maneuvers of the GEO satellite result in additional accelerations to the satellite itself.\\u000a Complex and difficult to model, these time varying accelerations are an important error source of precise orbit determination\\u000a (POD). In most POD practices, only non-maneuver orbital arcs are treated. However, for some applications such as satellite\\u000a navigation RDSS services, uninterrupted orbital ephemeris is demanded,

  1. Simulated retrievals for the remote sensing of CO2, CH4, CO, and H2O from geostationary orbit

    NASA Astrophysics Data System (ADS)

    Xi, X.; Natraj, V.; Shia, R. L.; Luo, M.; Zhang, Q.; Newman, S.; Sander, S. P.; Yung, Y. L.

    2015-06-01

    The Geostationary Fourier Transform Spectrometer (GeoFTS) is designed to measure high-resolution spectra of reflected sunlight in three near-infrared bands centered around 0.76, 1.6, and 2.3 ?m and to deliver simultaneous retrievals of column-averaged dry air mole fractions of CO2, CH4, CO, and H2O (denoted XCO2, XCH4, XCO, and XH2O, respectively) at different times of day over North America. In this study, we perform radiative transfer simulations over both clear-sky and all-sky scenes expected to be observed by GeoFTS and estimate the prospective performance of retrievals based on results from Bayesian error analysis and characterization. We find that, for simulated clear-sky retrievals, the average retrieval errors and single-measurement precisions are < 0.2% for XCO2, XCH4, and XH2O, and < 2% for XCO, when the a priori values have a bias of 3% and an uncertainty of 3%. In addition, an increase in the amount of aerosols and ice clouds leads to a notable increase in the retrieval errors and slight worsening of the retrieval precisions. Furthermore, retrieval precision is a strong function of signal-to-noise ratio and spectral resolution. This simulation study can help guide decisions on the design of the GeoFTS observing system, which can result in cost-effective measurement strategies while achieving satisfactory levels of retrieval precisions. The simultaneous retrievals at different times of day will be important for more accurate estimation of carbon sources and sinks on fine spatiotemporal scales and for studies to better understand the close coupling between the carbon and water cycles.

  2. Satellite voice broadcast system study, volume 2

    NASA Technical Reports Server (NTRS)

    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.

  3. The Principle of Navigation Constellation Composed of SIGSO Communication Satellites

    E-print Network

    Ji, Hai-Fu; Ai, Guo-Xiang; Shi, Hu-Li

    2012-01-01

    The Chinese Area Positioning System (CAPS), a navigation system based on GEO communication satellites, was developed in 2002 by astronomers at Chinese Academy of Sciences. Extensive positioning experiments of CAPS have been performed since 2005. On the basis of CAPS, this paper studies the principle of navigation constellation composed of Slightly Inclined Geostationary Orbit (SIGSO) communication satellites. SIGSO satellites are derived from end-of-life Geostationary Orbit (GEO) satellites under inclined orbit operation. Considering the abundant frequency resources of SIGSO satellites, multi-frequency observations could be conducted to enhance the precision of pseudorange measurements and ameliorate the positioning performence. The constellation composed of two GEO satellites and four SIGSO satellites with inclination of 5 degrees can provide the most territory of China with 24-hour maximum PDOP less than 42. With synthetic utilization of the truncated precise (TP) code and physical augmentation factor in fo...

  4. Communications satellite systems capacity analysis

    NASA Technical Reports Server (NTRS)

    Browne, L.; Hines, T.; Tunstall, B.

    1982-01-01

    Analog and digital modulation techniques are compared with regard to efficient use of the geostationary orbit by communications satellites. Included is the definition of the baseline systems (both space and ground segments), determination of interference susceptibility, calculation of orbit spacing, and evaluation of relative costs. It is assumed that voice or TV is communicated at 14/11 GHz using either FM or QPSK modulation. Both the Fixed-Satellite Service and the Broadcasting-Satellite Service are considered. For most of the cases examined the digital approach requires a satellite spacing less than or equal to that required by the analog approach.

  5. The infra red reflecting coverglass for silicon and GaAs solar cells used in near earth and geostationary orbits

    SciTech Connect

    Jones, G.; Mullaney, K.; Kitchen, C. [Pilkington Space Technology, Bodelwyddan (United Kingdom); Larue, J.C. [European Space Technology Centre, Noordwijk (Netherlands)

    1994-12-31

    An Infra Red Reflecting (IRR) coating has been developed at Space Technology for use with solar cell coverglasses. The IRR coating substantially improves the thermo-optical properties of Solar Cell Assemblies (SCAs) so allowing the array to run cooler and represents a significant advance over established UV reflective coatings. In-Orbit efficiency gains of between 2 and 6% have been predicted for a variety of solar cell types and orbits. The potential benefits of this technology are greatest for Non Reflective Silicon Solar Cells but equally so for Gallium Arsenide. The paper gives details of the development including the results of optimization, potential benefits in orbit (theoretical and practical) and the proposed Test Program.

  6. Evapotranspiration estimated by using datasets from the Chinese FengYun-2D geostationary meteorological satellite over the Yellow River source area

    NASA Astrophysics Data System (ADS)

    Liu, Rong; Wen, Jun; Wang, Xin; Zhang, Yu

    2015-01-01

    In this paper, we developed algorithms to estimate hourly evapotranspiration (ET) during a day under clear and cloud cover conditions using data from the Chinese FengYun-2D (FY-2D) geostationary meteorological satellite over the Yellow River source area. For cloud-free conditions, the Surface Energy Balance System (SEBS) methodology and FY-2D data were used to derive the hourly ET. For cloudy cover conditions, the transmission coefficient was calculated using top of atmosphere (TOA) reflectance and the attenuation of solar radiation in the atmosphere. Heat fluxes and ET under different atmospheric and cloud cover conditions were then calculated. Compared with ground-based measurements from eddy covariance systems deployed in the Maqu Climate and Environment Comprehensive Observation Station, the average relative error was 15.20% during the experimental period. The proposed methodology can rely exclusively on remote sensing data in the absence of ancillary ground observations. Thus, the proposed method can potentially estimate the regional surface energy budget.

  7. A heuristic for the multi-satellite, multi-orbit and multi-user management of Earth observation satellites

    Microsoft Academic Search

    Nicola Bianchessi; Jean-françois Cordeau; Jacques Desrosiers; Gilbert Laporte; Vincent Raymond

    2007-01-01

    Earth observation satellites are platforms equipped with optical instruments that orbit the Earth in order to take photographs of specific areas at the request of users. This article is concerned with the management of several satellites performing multiple orbits over a given planning horizon. It describes a tabu search heuristic for the problem of selecting and scheduling the requests to

  8. Scaling of solid state lasers for satellite power beaming applications

    Microsoft Academic Search

    Herbert W. Friedman; Georg F. Albrecht; Raymond J. Beach

    1994-01-01

    The power requirements for a satellite power beaming laser system depend upon the diameter of the beam director, the performance of the adaptive optics system, and the mission requirements. For an 8 meter beam director and overall Strehl ratio of 50%, a 30 kW laser at 850 nm can deliver an equivalent solar flux to a satellite at geostationary orbit.

  9. SATELLITE RAINFALL ESTIMATES: A LOOK BACK AND A PERSPECTIVE

    Microsoft Academic Search

    V. Levizzani

    Quantitative satellite rainfall estimates have always suffered from substantial limitations due to their VIS\\/IR brightness temperature mapping confined only to cloud top. MW data, though more responsive to cloud microphysics, are confined to polar orbits and suffer from spatial resolution drawbacks. A new chapter has started with the launch of the new generation of geostationary satellites (GOES and future MSG),

  10. An investigation of selected on-orbit satellite servicing issues

    NASA Technical Reports Server (NTRS)

    Hoffman, Stephen J.

    1986-01-01

    The results of three separate investigations performed by Science Applications International Corporation (SAIC) between August 1985 and October 1986 as the second phase of the two-phase Satellite Services System Program Plan contract for the Engineering Directorate of the Lyndon B. Johnson Space Center are discussed. The objectives of the first phase of this contract (reported in SAIC-85/1762) were to determine the potential for servicing a diverse range of spacecraft from the Space Shuttle Orbiter and to assess NASA's role as the catalyst in enabling routine on-orbit servicing. The second area of investigation was prompted by the need to understand satellite servicing requirements in the far term (1995 to 2010) and how results from the first phase of this contract could support these requirements. The mission model developed during the first phase was extended using new data and information from studies which address the later time period. The third area of investigation looked at a new servicing mode which had not been studied previously. This mode involves the on-orbit exchange of very large modules with masses greater than approximately 9,000 kilograms and/or lengths greater than approximately nine meters. The viewgraphs used for the final briefing for each of the three investigations, as presented to NASA are given.

  11. A case for natural colour imagery from geostationary satellites, and an approximation for the GOES-R ABI

    Microsoft Academic Search

    Steven D. Miller; Christopher C. Schmidt; Timothy J. Schmit; Donald W. Hillger

    2012-01-01

    ‘Natural’ (or ‘true’) colour imagery, so-called for its qualitative likeness to colour photography, is one of the most visually intuitive and readily communicable forms of satellite information. It is constructed by combining solar reflectance measurements from three narrow spectral bands defining the red, green and blue wavelengths of visible light. Natural colour facilitates the interpretation of multiple components in the

  12. Orbit determination of low-altitude earth satellites using GPS RF Doppler

    Microsoft Academic Search

    S. C. Wu; V. J. Ondrasik

    1982-01-01

    This paper investigates the use of one type of GPS-signal derived measurement, the doubly differenced GPS RF Doppler, in the orbit determination of low-altitude earth satellites. This measurement is simple to make, is insensitive to clock errors and provides a continuous determination of the user satellite orbit. Analysis shows that, with a constellation of 18 GPS satellites and 13 ground

  13. An overview of the IRIDIUM (R) low Earth orbit (LEO) satellite system

    Microsoft Academic Search

    Carl E. Fossa; Richard A. Raines; Gregg H. Gunsch; Michael A. Temple

    1998-01-01

    This paper provides a tutorial overview of the IRIDIUM(R) low earth orbit (LEO) satellite system. Section I contains an introduction to the IRIDIUM(R) network as well as the system specifications. Section II discusses the satellite constellation design, orbital parameters, and horizontal pointing angles between satellites. Section III introduces the idea of time dependent connectivity in a mobile network, and analyzes

  14. The infra red reflecting coverglass for silicon and GaAs solar cells used in near Earth and geostationary orbits

    Microsoft Academic Search

    G. Jones; K. Mullaney; C. Kitchen; J. C. Larue

    1994-01-01

    An infra red reflecting (IRR) coating has been developed at Space Technology for use with solar cell coverglasses. The IRR coating substantially improves the thermo-optical properties of solar cell assemblies (SCAs) so allowing the array to run cooler and represents a significant advance over established UV reflective coatings. In-orbit efficiency gains of between 2 and 6% have been predicted for

  15. A method of astronomical autonomous orbit and attitude determinations for satellites

    NASA Astrophysics Data System (ADS)

    Lin-lin, Li; Hui-xian, Sun

    2003-10-01

    A method of realtime autonomous orbit determination for earth satellites using the extended Kalman filtering is proposed. The observed quantities are: the satellite-sun direction vector measured by a sun sensor, the satellite-earth and satellite-moon direction vectors measured by an ultraviolet sensor, and the geocentric distance measured by a radar altimeter. At the same time the satellite attitude to the earth is also determined. Results of our simulation of the autonomous orbit determination show that the precision of the orbit determinations is better than 200 m. The effects of the sampling period, orbital inclination, orbital eccentricity and orbital altitude on the precision of orbit determination are analyzed and compared, and certain principles helpful for improving the precision of orbit determination are suggested.

  16. Earth satellite orbits with resonant lunisolar perturbations. I - Resonances dependent only on inclination

    Microsoft Academic Search

    S. Hughes

    1980-01-01

    Earth satellite orbits resonant with respect to lunisolar gravity and direct solar radiation pressure perturbations are discussed with particular reference to those resonances the occurrence of which is dependent only on the satellite's orbital inclination. All types of lunisolar resonance orbits are first classified in terms of the general commensurability condition, which is then expressed as a function of the

  17. Precise SAR satellite orbit parameters determination based on Ground Control Points

    Microsoft Academic Search

    Bin Pan; Ling Liu

    2010-01-01

    Aim to solve the georeferencing problem of spaceborne SAR imagery, accounting for the orbit physics model and the impact of the earth perturbations, some description models such as four parameters model and polynomial model could be applied to determine the satellite orbit parameters. However the orbit state vectors solved by 5 satellite state vectors supplied by header file in SAR

  18. Analysis on the long term orbital evolution of Molniya satellites

    NASA Astrophysics Data System (ADS)

    Zhu, Ting-Lei; Zhao, Chang-Yin; Wang, Hong-Bo; Zhang, Ming-Jiang

    2015-06-01

    Long term evolution of the Molniya satellites are investigated by means of historical data analysis, theoretical analysis and numerical integration. Both the mean motion resonance problem and the critical inclination problem are studied. The period and the amplitude of the semi-major axis for each satellite are obtained analytically and compared with the observational data. In addition, the reason of the observed sudden changes in the center and the amplitude of the oscillating semi-major axes is determined as the effect of the atmosphere drag. For the long period perigee motion, the dominant perturbations come from the luni-solar gravity. A two-degree-of freedom system is established by adding the two periodic terms of the neighbor resonances to the Hamiltonian of the classical single resonance model. In theory, the resulting resonance overlap model is responsible for the chaotic layer between the libration region and the circulation region. In practice, it is applied to explain the quick decay of the earliest Molniya satellites and to study the satellites that still orbiting the Earth at present.

  19. Lunar tidal acceleration from earth satellite orbit analyses

    NASA Astrophysics Data System (ADS)

    Cazenave, A.; Daillet, S.

    1981-03-01

    Results are presented for the M2 and O1 ocean tides based on the Starlette satellite orbit analyses from which the tidal acceleration of the moon is derived. The solution for M2 is consistent with previous satellite solutions; for O1 a phase lag is found which is approximately zero. The uncertainty is still large, but there is an indication that the tidal dissipation at the O1 frequency is small. Using the weighted mean value of the best satellite solutions gives a tidal acceleration of the moon of -21.32 plus or minus 1.25 arcsec/century per century for the total dissipation in the earth at the M2 frequency. In principle, comparison between the lunar tidal acceleration derived from the satellite solution and the lunar tidal acceleration derived from numerical models gives the amount of dissipation in the solid earth, but uncertainties are still too large to give a reliable estimate of the tidal mantle Q.

  20. Meteorological satellites

    NASA Technical Reports Server (NTRS)

    Allison, L. J. (editor); Schnapf, A.; Diesen, B. C., III; Martin, P. S.; Schwalb, A.; Bandeen, W. R.

    1980-01-01

    An overview is presented of the meteorological satellite programs that have been evolving from 1958 to the present, and plans for the future meteorological and environmental satellite systems that are scheduled to be placed into service in the early 1980's are reviewed. The development of the TIROS family of weather satellites, including TIROS, ESSA, ITOS/NOAA, and the present TIROS-N (the third generation operational system) is summarized. The contribution of the Nimbus and ATS technology satellites to the development of the operational-orbiting and geostationary satellites is discussed. Included are descriptions of both the TIROS-N and the DMSP payloads currently under development to assure a continued and orderly growth of these systems into the 1980's.

  1. Aerodynamic Stability of Satellites in Elliptic Low Earth Orbits

    E-print Network

    Bailey, Matthew; Mancas, Stefan C; Udrea, Bogdan; Umeadi, Uchenna

    2013-01-01

    Topical observations of the thermosphere at altitudes below $200 \\, km$ are of great benefit in advancing the understanding of the global distribution of mass, composition, and dynamical responses to geomagnetic forcing, and momentum transfer via waves. The perceived risks associated with such low altitude and short duration orbits has prohibited the launch of Discovery-class missions. Miniaturization of instruments such as mass spectrometers and advances in the nano-satellite technology, associated with relatively low cost of nano-satellite manufacturing and operation, open an avenue for performing low altitude missions. The time dependent coefficients of a second order non-homogeneous ODE which describes the motion have a double periodic shape. Hence, they will be approximated using Jacobi elliptic functions. Through a change of variables the original ODE will be converted into Hill's ODE for stability analysis using Floquet theory. We are interested in how changes in the coefficients of the ODE affect the ...

  2. Artificial Crater Formation on Satellite Surfaces Using an Orbiting Railgun

    NASA Technical Reports Server (NTRS)

    Dissly, R. W.; Miller, K. L.; Carlson, R. J.

    2003-01-01

    The specification of greater than 45kW of disposable power available on the JIMO spacecraft raises the possibility of a new class of instrumentation that has utility at such power levels. In this presentation we discuss the concept of an electromagnetic mass driver that can launch projectiles from orbit around one of the Galilean satellites directed on a trajectory that will impact the satellite surface. The resulting impact will create a crater that will provide information on the mechanical properties of surface and near-surface materials, expose subsurface materials for remote spectral identification, and form a vapor cloud that can be sensed for composition either remotely or in-situ. An analog for such a controlled cratering experiment is Deep Impact, a mission to observe the crater and ensuing ejecta cloud formed by a ballistic projectile into a comet surface in July, 2005.

  3. A high-fidelity satellite ephemeris program for Earth satellites in eccentric orbits

    NASA Technical Reports Server (NTRS)

    Simmons, David R.

    1990-01-01

    A program for mission planning called the Analytic Satellite Ephemeris Program (ASEP), produces projected data for orbits that remain fairly close to the Earth. ASEP does not take into account lunar and solar perturbations. These perturbations are accounted for in another program called GRAVE, which incorporates more flexible means of input for initial data, provides additional kinds of output information, and makes use of structural programming techniques to make the program more understandable and reliable. GRAVE was revised, and a new program called ORBIT was developed. It is divided into three major phases: initialization, integration, and output. Results of the program development are presented.

  4. Orbit Optimization and Scattering Coefficient Analysis for the Proposed GLORIA System

    NASA Technical Reports Server (NTRS)

    Welch, Bryan

    2004-01-01

    This paper investigates the optimization of an orbit for a Low-Earth Orbiting (LEO) satellite for coastal coverage over Antarctic and United States shorelines as part of the Geostationary/Low-Earth Orbiting Radar Image Acquisition (GLORIA) System. Simulations over a range of orbital parameters are performed to determine the optimal orbit. Scattering coefficients are computed for the optimal orbit throughout the day and characterized to compare various scenarios for which link budget comparisons could then be made.

  5. The Effect of GPS Ephemeris on the Accuracy of Precise Orbit Determination of LEO Satellite-borne GPS

    Microsoft Academic Search

    Dong-Ju Peng; Bin Wu

    2009-01-01

    The satellite-borne GPS receivers dedicated to precise orbit determination are now being carried by more and more low earth orbit (LEO) satellites and the satellite-borne GPS has become one of the main means for the precise orbit determination of low earth orbit satellites. The accuracy of satellite-borne GPS precise orbit determination depends on the accuracies of the GPS ephemeris and

  6. The Geostationary Atmospheric Sounder (GAS)

    NASA Astrophysics Data System (ADS)

    Christensen, Jacob; Carlström, Anders; Emrich, Anders; de Maagt, Peter

    2006-09-01

    Millimeter and Sub-mm-wave imagers/sounders are considered for future meteorological geostationary satellite missions. A novel interferometric Geostationary Atmospheric Sounder (GAS) has been developed and a concept demonstrator is under construction. The concept is a response to the requirements of observations for nowcasting and short range forecasting in 2015-2025, as determined by EUMETSAT for post-MSG operational satellites observations. Prioritized parameters include vertical profiles of temperature and humidity with high temporal and horizontal resolution (15 min and 30 km) under all weather conditions. Frequency bands around 53GHz, 118GHz, 183GHz, 380GHz have the highest user priority and are all supported by GAS. The instrument relies on an innovative configuration of interferometer elements which enables the use of a sparse array and simplifies calibration.

  7. Analysing the Orbital Movement and Trajectory of LEO (Low Earth Orbit) Satellite Relative to Earth Rotation

    NASA Astrophysics Data System (ADS)

    Bohra, Nafeesa; de Meer, Hermann; Memon, Aftab. A.

    Next generation of wireless Internet scenarios include LEOs (Low Earth Orbit Satellites). Lower altitudes of LEO constellations could allow global coverage while offering: low end-to-end propagation delay, low power consumption, and effective frequency usage both for the users and the satellite network. LEOs rotate asynchronously to the earth rotation. Fast movement of LEOs makes it necessary to include efficient mobility management. In past few years mobility patterns have been proposed by considering the full earth coverage constellation whereby, the rotation of earth was often assumed too negligible to be taken into account. The prime objective of this study is to provide facts and figures that show LEOs traverse relative to the rotation of earth. In order to analyse the orbital movement and trajectory of LEOs relative to earth rotation mathematical analysis have been done and justification have been made through equations.

  8. Laser beaming demonstrations to high-orbit satellites

    SciTech Connect

    Lipinski, R.J.; Meister, D.C.; Tucker, S. [Sandia National Labs., Albuquerque, NM (United States)] [and others

    1994-12-31

    Laser power beaming to satellites and orbital transfer vehicles requires the accurate pointing of a low-divergence laser beam to its target, whether the target is in the sunlight or the earth`s shadow. The Air Force Phillips Laboratory (AFPL) has demonstrated reduction in the image size of stars by a factor of 10 or more by using laser beacons and adaptive optics for atmospheric compensation. This same technology is applicable to reducing the divergence of laser beams propagated from earth to space. A team of Phillips Laboratory, COMSAT Laboratories, and Sandia National Laboratories plans to demonstrate the state of the art in this area with laser-beaming demonstrations to high-orbit satellites. The demonstrations will utilize the 1.5-m diameter telescope with adaptive optics at the AFPL Starfire Optical Range (SOR) and a ruby laser provided by the Air Force and Sandia (1--50 kW and 6 ms at 694.3 nm). The first targets will be corner-cube retro-reflectors left on the moon by the Apollo 11, 14, and 15 landings. The authors will attempt to use adaptive optics for atmospheric compensation to demonstrate accurate and reliable beam projection with a series of shots over a span of time and shot angle. The authors will utilize the return signal from the retro-reflectors to help determine the beam diameter on the moon and the variations in pointing accuracy caused by atmospheric tilt. This will be especially challenging because the retro-reflectors will need to be in the lunar shadow to allow detection over background light. If the results from this experiment are encouraging, the authors will at a later date direct the beam at a COMSAT satellite in geosynchronous orbit as it goes into the shadow of the earth. The authors will utilize an onboard monitor to measure the current generated in the solar panels on the satellite while the beam is present. A threshold irradiance of about 4 W/m{sup 2} on orbit is needed for this demonstration.

  9. Orbits of the Martian satellites from ESAPHO and ESADE theories

    NASA Astrophysics Data System (ADS)

    Chapront-Touze, M.

    1990-12-01

    The semi-analytical theories ESAPHO and ESADE for the orbital motions of the Martian satellites have been fitted to a large collection of observations including earth-based observations and spacecraft observations from Mariner 9, Viking 1 and 2 and Phobos 2. The influences of various subsets of observations and of the weights assigned to them have been analyzed. The contribution of the perturbations by Phobos' figure has been studied. An interesting agreement of the perturbations computed from Borderies and Yoder's values of inertial parameters with the observations has been obtained.

  10. Laser beaming demonstrations to high-orbit satellites

    SciTech Connect

    Lipinski, R.J.; Meister, D.C.; Tucker, S. [and others

    1993-12-31

    Laser power beaming to satellites and orbital transfer vehicles requires the accurate pointing of a low-divergence laser beam to its target, whether the target is in the sunlight or the earth`s shadow. The Air Force Phillips Laboratory (AFPL) has demonstrated reduction in the image size of stars by a factor of 10 or more by using laser beacons and adaptive optics for atmospheric compensation. This same technology is applicable to reducing the divergence of laser beams propagated from earth to space. A team of Phillips Laboratory, COMSAT Laboratories, and Sandia National Laboratories plans to demonstrate the state of the art in this area with laser-beaming demonstrations to high-orbit satellites. The demonstrations will utilize the 1.5-m diameter telescope with adaptive optics at the AFPL Starfire Optical Range (SOR) and a ruby laser provided by the Air Force and Sandia (1--50 kill and 6 ms at 694.3 nm). The first targets will be corner-cube retro-reflectors left on the moon by the Apollo 11, 14, and 15 landings. We will attempt to use adaptive optics for atmospheric compensation to demonstrate accurate and reliable beam projection with a series of shots over a span of time and shot angle. We will utilize the return signal from the retro-reflectors to help determine the beam diameter on the moon and the variations in pointing accuracy caused by atmospheric tilt. This will be especially challenging because the retro-reflectors will need to be in the lunar shadow to allow detection over background light. If the results from this experiment are encouraging, we will at a later date direct the beam at a COMSAT satellite in geosynchronous orbit as it goes into the shadow of the earth. We will utilize an onboard monitor to measure the current generated in the solar panels on the satellite while the beam is present. A threshold irradiance of about 4 W/m{sup 2} on orbit is needed for this demonstration.

  11. Analysis of Errors in a Special Perturbations Satellite Orbit Propagator

    SciTech Connect

    Beckerman, M.; Jones, J.P.

    1999-02-01

    We performed an analysis of error densities for the Special Perturbations orbit propagator using data for 29 satellites in orbits of interest to Space Shuttle and International Space Station collision avoidance. We find that the along-track errors predominate. These errors increase monotonically over each 36-hour prediction interval. The predicted positions in the along-track direction progressively either leap ahead of or lag behind the actual positions. Unlike the along-track errors the radial and cross-track errors oscillate about their nearly zero mean values. As the number of observations per fit interval decline the along-track prediction errors, and amplitudes of the radial and cross-track errors, increase.

  12. Satellite gravitational orbital perturbations and the gravitomagnetic clock effect

    E-print Network

    Lorenzo Iorio

    2001-08-19

    In order to detect the gravitomagnetic clock effect by means of two counter-orbiting satellites placed on identical equatorial and circular orbits around the Earth with radius 7000 km their radial and azimuthal positions must be known with an accuracy of delta r =10^{-1} mm and delta phi =10^{-2} mas per revolution. In this work we investigate if the radial and azimuthal perturbations induced by the dynamical and static parts of the Earth' s gravitational field meet this requirements. While the radial direction is affected only by harmonic perturbations with periods up to some tens of days, the azimuthal location is perturbed by a secular drift and very long period effects.It results that the present level of accuracy in the knowledge both of the Earth solid and ocean tides, and of the static part of the geopotential does not allow an easy detection of the gravitomagnetic clock effect, at least by using short arcs only.

  13. IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1 Fade Slope Analysis of Ka-Band Earth-LEO Satellite

    E-print Network

    Michelson, David G.

    those observed at selected sites during the Advanced Communications Technology Satellite program meteorological factors, satellite communications. I. INTRODUCTION ALTHOUGH rain fading on Earth-space links to increase the capacity of conven- tional communications satellites located in geostationary Earth orbit (GEO

  14. Geostationary Earth Radiation Budget (gerb): Validation Results

    NASA Astrophysics Data System (ADS)

    Russell, J. E.; Harries, J. E.; Clearbaux, N.

    2006-08-01

    The Geostationary Earth Radiation Budget (GERB) instrument on METEOSAT-8 is making the first measurements of the Earth’s radiation budget from geostationary orbit. The first validated GERB Edition 1 products were released to the scientific community via the ggsps archive (http://ggsps.rl.ac.uk) earlier this year. This paper summaries the calibration accuracy and validation results for these Edition 1 products.

  15. Applications Technology Satellites -F and -G.

    NASA Technical Reports Server (NTRS)

    Gerwin, H. L.

    1972-01-01

    The objectives of the Applications Technology Satellite (ATS) Program are to advance space technology in areas of importance to mankind. A brief description of the planned satellites and experiments is presented. The experiments include instructional television, communications, navigation, meteorology, spacecraft technology and science. The ATS-F and -G satellites will have 30-foot deployable antennas and will serve as three-axis stabilized platforms in geostationary orbit with 0.1 degree pointing accuracy.

  16. Spin parameters of Low Earth Orbiting satellites Larets and Stella determined from Satellite Laser Ranging data

    NASA Astrophysics Data System (ADS)

    Kucharski, D.; Lim, H.-C.; Kirchner, G.; Koidl, F.

    2014-01-01

    Satellite Laser Ranging (SLR) measurements contain information about the spin parameters of the fully passive, geodetic satellites. In this paper we spectrally analyze the SLR data of 5 geodetic satellites placed on the Low Earth Orbits: GFZ-1, WESTPAC, Larets, Starlette, Stella, and successfully retrieve the frequency signal from Larets and Stella only. The obtained signals indicate an exponential increase of the spin period of Larets: T = 0.860499·exp(0.0197066·D) [s], and Stella: T = 13.5582·exp(0.00431232·D) [s], where D is in days since launch. The initial spin periods calculated from the first month of the SLR observations are: Larets: Tinitial = 0.8239 s, Stella: Tinitial = 13.2048 s. Analysis of the apparent effects indicates the counter-clockwise spin direction of the satellites. The twice more heavy Stella lost its rotational energy more than four times slower than Larets. Fitting the spin model to the observed spin trends allows determination of the spin axis orientation evolution for Larets and Stella before their rotational period becomes equal to the orbital period.

  17. Long-term evolution of navigation satellite orbits: GPS\\/GLONASS\\/GALILEO

    Microsoft Academic Search

    C. C. Chao; R. A Gick

    2004-01-01

    A recent study was performed to examine whether long-term growth in the eccentricity evolution exists for the disposal orbits of navigation satellite systems such as GPS, GLONASS, and GALILEO. Previous studies examined the orbit stability for GPS Block II satellites. The orbits of the non-operational GPS Block I satellites are included in this study because they are at 63.4° inclination,

  18. On the Distribution of Orbital Poles of Milky Way Satellites

    E-print Network

    Christopher Palma; Steven R. Majewski; Kathryn V. Johnston

    2001-08-29

    In numerous studies of the outer Galactic halo some evidence for accretion has been found. If the outer halo did form in part or wholly through merger events, we might expect to find coherent streams of stars and globular clusters following similar orbits as their parent objects, which are assumed to be present or former Milky Way dwarf satellite galaxies. We present a study of this phenomenon by assessing the likelihood of potential descendant ``dynamical families'' in the outer halo. We conduct two analyses: one that involves a statistical analysis of the spatial distribution of all known Galactic dwarf satellite galaxies (DSGs) and globular clusters, and a second, more specific analysis of those globular clusters and DSGs for which full phase space dynamical data exist. In both cases our methodology is appropriate only to members of descendant dynamical families that retain nearly aligned orbital poles today. Since the Sagittarius dwarf (Sgr) is considered a paradigm for the type of merger/tidal interaction event for which we are searching, we also undertake a case study of the Sgr system and identify several globular clusters that may be members of its extended dynamical family. (ABRIDGED)

  19. An experimental geostationary platform - A step toward the 1990's

    NASA Technical Reports Server (NTRS)

    Carey, W. T., Jr.

    1982-01-01

    NASA studies on geostationary platforms are reviewed. Traffic models for geostationary missions through the year 2000 are presented, and the benefits of platforms are shown, as compared with accomplishing the same missions on specialized satellites. These benefits are illustrated by a case study (involving Leasat) demonstrating that substantial cost savings can result because of economies of scale. Technologies in need of development and demonstration are identified, and attention is given to the potential NASA Experimental Geostationary Platform.

  20. Investigation of biomass burning and aerosol loading and transport in South America utilizing geostationary satellites. Annual report, January-December 1995

    SciTech Connect

    Menzel, P.; Prins, E.

    1995-12-01

    This study attempts to assess the extent of burning and associated aerosol transport regimes in South America and the South Atlantic using geostationary satellite observations, in order to explore the possible roles of biomass burning in climate change and more directly in atmospheric chemistry and radiative transfer processes. Modeling and analysis efforts have suggested that the direct and indirect radiative effects of aerosols from biomass burning may play a major role in the radiative balance of the earth and are an important factor in climate change calculations. One of the most active regions of biomass burning is located in South America, associated with deforestation in the selva (forest), grassland management, and other agricultural practices. As part of the NASA Aerosol Interdisciplinary Program, the authors are utilizing GOES-7 (1988) and GOES-8 (1995) visible and multispectral infrared data (4, 11, and 12 microns) to document daily biomass burning activity in South America and to distinguish smoke/aerosols from other multi-level clouds and low-level moisture. This study catalogues the areal extent and transport of smoke/aerosols throughout the region and over the Atlantic Ocean for the 1988 (July-September) and 1995 (June-October) biomass burning seasons. The smoke/haze cover estimates are compared to the locations of fires to determine the source and verify the haze is actually associated with biomass burning activities. The temporal resolution of the GOES data (half-hourly in South America) makes it possible to determine the prevailing circulation and transport of aerosols by considering a series of visible and infrared images and tracking the motion of smoke, haze and adjacent clouds. The study area extends from 40 to 70 deg W and 0 to 40 deg S with aerosol coverage extending over the Atlantic Ocean when necessary. Fire activity is estimated with the GOES Automated Biomass Burning Algorithm (ABBA).

  1. A combined deficit index for regional agricultural drought assessment over semi-arid tract of India using geostationary meteorological satellite data

    NASA Astrophysics Data System (ADS)

    Vyas, Swapnil S.; Bhattacharya, Bimal K.; Nigam, Rahul; Guhathakurta, Pulak; Ghosh, Kripan; Chattopadhyay, N.; Gairola, R. M.

    2015-07-01

    The untimely onset and uneven distribution of south-west monsoon rainfall lead to agricultural drought causing reduction in food-grain production with high vulnerability over semi-arid tract (SAT) of India. A combined deficit index (CDI) has been developed from tri-monthly sum of deficit in antecedent rainfall and deficit in monthly vegetation vigor with a lag period of one month between the two. The formulation of CDI used a core biophysical (e.g., NDVI) and a hydro-meteorological (e.g., rainfall) variables derived using observation from Indian geostationary satellites. The CDI was tested and evaluated in two drought years (2009 and 2012) within a span of five years (2009-2013) over SAT. The index was found to have good correlation (0.49-0.68) with standardized precipitation index (SPI) computed from rain-gauge measurements but showed lower correlation with anomaly in monthly land surface temperature (LST). Significant correlations were found between CDI and reduction in agricultural carbon productivity (0.67-0.83), evapotranspiration (0.64-0.73), agricultural grain yield (0.70-0.85). Inconsistent correlation between CDI and ET reduction was noticed in 2012 in contrast to consistent correlation between CDI and reduction in carbon productivity both in 2009 and 2012. The comparison of CDI-based drought-affected area with those from existing operational approach showed 75% overlapping regions though class-to-class matching was only 40-45%. The results demonstrated that CDI is a potential indicator for assessment of late-season regional agricultural drought based on lag-response between water supply and crop vigor.

  2. Satellite Communications in the 1980's.

    ERIC Educational Resources Information Center

    Usunier, Pierre

    Space communications have developed tremendously since 1963 when the National Aeronautics and Space Administration (NASA) launched the synchronous communication satellite, Syncom II, into geostationary orbit. The capacity of that spacecraft was one two-circuit voice channel. Intelsat V, launched in 1980, has a capacity of 12,000 circuits plus two…

  3. The National Polar-orbiting Operational Environmental Satellite System

    NASA Astrophysics Data System (ADS)

    Bloom, H.

    The tri-agency Integrated Program Office (IPO) is responsible for managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the current military and civilian operational polar-orbiting ``weather'' satellites. The Northrop Grumman Space Technology - Raytheon team was competitively selected in 2002 as the Acquisition and Operations contractor team to develop, integrate, deploy, and operate NPOESS satellites to meet the tri-agency user requirements for NPOESS over the 10-year (2009-2018) operational life of the program. Beginning in 2009, NPOESS spacecraft will be launched into three orbital planes to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving operational ``weather'' satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - atmosphere, ocean, land, and the space environment. In recent years, the operational weather forecasting and climate science communities have levied more rigorous requirements on space-based observations of the Earth's system that have significantly increased demands on performance of the instruments, spacecraft, and ground systems required to deliver NPOESS data, products, and information to end users. The ``end-to-end'' system consists of: the spacecraft; instruments and sensors on the spacecraft; launch support capabilities; the command, control, communications, and data routing infrastructure; and data processing hardware and software. NPOESS will observe significantly more phenomena simultaneously from space than its operational predecessors. NPOESS is expected to deliver large volumes of more accurate measurements at higher spatial (horizontal and vertical) and temporal resolution at much higher data rates and with more frequent space-to-ground data communications than are currently in use. When NPOESS reaches full operational capability in 2013, spacecraft in all three orbital planes will provide global coverage with a data refresh rate of approximately four hours for most observations. User demands for more real-time data from NPOESS are driving the space and ground-based architectures for data routing and retrieval that will dramatically shorten data latency. To meet user-validated requirements for 55 geophysical parameters, NPOESS will deliver global data to four U.S. centers for processing and distribution to end users. Global data will be down-linked to 15 globally-distributed, low-cost, unmanned ground stations that will be tied to these four processing centers via commercial fiber-optic networks. This innovative ground system will deliver 75% of the global (daily average) within 15 minutes and 95% of the data (daily average) within 26 minutes from the time of on-orbit collection. NPOESS spacecraft will also simultaneously broadcast two types of real-time data to suitably equipped ground stations. Early flight-testing of instruments will reduce development risk and demonstrate and validate global imaging and sounding instruments, algorithms, and pre-operational ground systems prior to the first NPOESS flight in 2009. Four NPOESS sensors are scheduled to fly on the joint National Aeronautics and Space Administration (NASA)/IPO NPOESS Preparatory Project (NPP) mission in 2006. Early system-level integration and testing will provide ``lessons learned'' and allow for any required modifications in time to support readiness for the first NPOESS launch in 2009. NPP will demonstrate the utility of improved imaging and radiometric data in short-term weather ``nowcasting'' and forecasting and in other oceanic and terrestrial applications, such as harmful algal blooms, volcanic ash, and wildfire detection. NPP will help ensure continuity of important climate-quality measurements during the transition from NASA's Earth Observing System Terra and Aqua research mis

  4. Study of tropical deep convective processes and water vapor variations using nasa a-train data and geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Takahashi, Hanii

    The theme of this dissertation is to use various satellite observations to seek new insights into our understating of tropical deep convective processes and water vapor variations. Three subjects are investigated: 1) observational determination of level of neutral buoyancy (LNB) for deep convection, 2) characters and life stage view of tropical overshooting convection (OSC), and 3) variations of water vapor and clouds during East Pacific (EP)- and Central Pacific (CP)-El Ninos. The first study conducts a near-global survey of LNB for tropical deep convection using CloudSat (LNB_observation) and makes comparison with the corresponding LNB based on the parcel theory using ambient sounding (LNB_sounding). The principal findings are as follows: First, although LNB_sounding provides a reasonable upper bound for convective development, ambient sounding contains limited information for predicting the actual LNB. Second, LNB_sounding significantly overestimates the "destination" height level of the detrained mass. Third, LNB_observation is consistently higher over land than over ocean, although LNB_sounding is similar between land and ocean, suggesting some fundamental differences between land and ocean convection. The second study uses CloudSat data together with ISCCP CT to study tropical OSC properties and the convective systems in which they are embedded. Our results find that, nearly 21 % of tropical deep convection is overshooting; the occurrence frequency is only slightly higher over land (~ 50.2 %) than over ocean (~ 49.8 %). Various proxies of convective strength are analyzed showing consistently that continental OSC is stronger than the oceanic counterpart. Moreover, majority (2/3) of the OSC occurs during the growing stage of the convective systems. About 1/3 occurs during the mature stage, which are more abundant over land during noontime. The third study shows that EP- and CP-El Nino events produce different patterns of water vapor and cloud anomalies over the tropical ocean. Regression of water vapor anomalies onto the Nino-3.4 sea surface temperature shows a clear "upper tropospheric amplification" of the fractional water vapor change. Furthermore, water vapor and cloud anomalies in different circulation regimes are examined. Finally, Geophysical Fluid Dynamics Laboratory AM2.1 model simulations of water vapor and clouds are compared with the satellite observations.

  5. GeoSTAR - A Synthetic Aperture Microwave Sounder for Geostationary Missions

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn; Wilson, William; Tanner, Alan; Kangaslahti, Pekka

    2004-01-01

    The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new microwave atmospheric sounder under development. It will bring capabilities similar to those now available on low-earth orbiting environmental satellites to geostationary orbit - where such capabilities have not been available. GeoSTAR will synthesize the multimeter aperture needed to achieve the required spatial resolution, which will overcome the obstacle that has prevented a GEO microwave sounder from being implemented until now. The synthetic aperture approach has until recently not been feasible, due to the high power needed to operate the on-board high-speed massively parallel processing system required for 2D-synthesis, as well as a number of system and calibration obstacles. The development effort under way at JPL, with important contributions from the Goddard Space Flight Center and the University of Michigan, is intended to demonstrate the measurement concept and retire much of the technology risk.

  6. In-orbit assessment of laser retro-reflector efficiency onboard high orbiting satellites

    NASA Astrophysics Data System (ADS)

    Wilkinson, Matthew; Appleby, Graham

    2011-08-01

    The navigation and geodetic satellites that orbit the Earth at altitudes of approximately 20,000 km are tracked routinely by many of the Satellite Laser Ranging (SLR) stations of the International Laser Ranging Service (ILRS). In order to meet increasing demands on SLR stations for daytime and nighttime observations, any new mission needs to ensure a strong return signal so that the target is easily acquirable. The ILRS has therefore set a minimum effective cross-section of 100 million square metres for the on-board laser retro-reflector arrays (LRAs) and further recommends the use of 'uncoated' cubes in the arrays. Given the large number of GNSS satellites that are currently supported by SLR, it is informative to make an assessment of the relative efficiencies of the various LRAs employed. This paper uses the laser ranging observations themselves to deduce and then compare the efficiencies of the LRAs on the COMPASS-M1 navigation satellite, two satellites from the GPS and three from the GLONASS constellations, the two GIOVE test satellites from the upcoming Galileo constellation, the two Etalon geodetic spheres and the geosynchronous communications test satellite, ETS-8. All the LRAs on this set of satellites employ back-coated retro-reflector cubes, except those on the COMPASS-M1 and ETS-8 vehicles which are uncoated. A measure of return signal strength, and thus of LRA-efficiency, is calculated using the laser-range full-rate data archive from 2007 to 2010, scaled to remove the effects of variations in satellite range, atmospheric attenuation and retro-reflector target total surface area. Observations from five SLR stations are used in this study; they are Herstmonceux (UK), Yarragadee (Australia), Monument Peak and McDonald (USA) and Wettzell (Germany). Careful consideration is given to the treatment of the observations from each station in order to take account of local working practices and system upgrades. The results show that the uncoated retro-reflector cubes offer significant improvements in efficiency.

  7. Considering a satellite orbit as a space curve in terms of Differential Geometry, we succeed to merge orbital rotation and curvature measures by means of Cartan

    E-print Network

    Stuttgart, Universität

    Considering a satellite orbit as a space curve in terms of Differential Geometry, we succeed characteristics (curvature measures) of the GOCE satellite by means of a simulated orbit (5 revolutions Stuttgart, Germany Orbital rotations of a satellite: Case study GOCE GOCE gradiometry 3-dimensional

  8. Estimating urban temperature bias using polar-orbiting satellite data

    NASA Technical Reports Server (NTRS)

    Johnson, Gregory L.; Davis, Jerry M.; Karl, Thomas R.; Mcnab, Alan L.; Gallo, Kevin P.; Tarpley, J. Dan; Bloomfield, Peter

    1994-01-01

    Urban temperature bias, defined to be the difference between a shelter temperature reading of unknown but suspected urban influence and some appropriate rural reference temperature, is estimated through the use of polar-orbiting satellite data. Predicted rural temperatures, based on a method developed using sounding data, are shown to be of reasonable accuracy in many cases for urban bias assessments using minimum temperature data from selected urban regions in the United States in July 1989. Assessments of predicted urban bias were based on comparisons with observed bias, as well as independent measures of urban heat island influence, such as population statistics and urban-rural differences in a vegetation index. This technique provides a means of determining urban bias in regions where few if any rural reference stations are available, or where inhomogeneities exist in land surface characteristics or rural station locations.

  9. Spacecraft design project: Low Earth orbit communications satellite

    NASA Technical Reports Server (NTRS)

    Moroney, Dave; Lashbrook, Dave; Mckibben, Barry; Gardener, Nigel; Rivers, Thane; Nottingham, Greg; Golden, Bill; Barfield, Bill; Bruening, Joe; Wood, Dave

    1991-01-01

    This is the final product of the spacecraft design project completed to fulfill the academic requirements of the Spacecraft Design and Integration 2 course (AE-4871) taught at the U.S. Naval Postgraduate School. The Spacecraft Design and Integration 2 course is intended to provide students detailed design experience in selection and design of both satellite system and subsystem components, and their location and integration into a final spacecraft configuration. The design team pursued a design to support a Low Earth Orbiting (LEO) communications system (GLOBALSTAR) currently under development by the Loral Cellular Systems Corporation. Each of the 14 team members was assigned both primary and secondary duties in program management or system design. Hardware selection, spacecraft component design, analysis, and integration were accomplished within the constraints imposed by the 11 week academic schedule and the available design facilities.

  10. SPICE Module for the Satellite Orbit Analysis Program (SOAP)

    NASA Technical Reports Server (NTRS)

    Coggi, John; Carnright, Robert; Hildebrand, Claude

    2008-01-01

    A SPICE module for the Satellite Orbit Analysis Program (SOAP) precisely represents complex motion and maneuvers in an interactive, 3D animated environment with support for user-defined quantitative outputs. (SPICE stands for Spacecraft, Planet, Instrument, Camera-matrix, and Events). This module enables the SOAP software to exploit NASA mission ephemeris represented in the JPL Ancillary Information Facility (NAIF) SPICE formats. Ephemeris types supported include position, velocity, and orientation for spacecraft and planetary bodies including the Sun, planets, natural satellites, comets, and asteroids. Entire missions can now be imported into SOAP for 3D visualization, playback, and analysis. The SOAP analysis and display features can now leverage detailed mission files to offer the analyst both a numerically correct and aesthetically pleasing combination of results that can be varied to study many hypothetical scenarios. The software provides a modeling and simulation environment that can encompass a broad variety of problems using orbital prediction. For example, ground coverage analysis, communications analysis, power and thermal analysis, and 3D visualization that provide the user with insight into complex geometric relations are included. The SOAP SPICE module allows distributed science and engineering teams to share common mission models of known pedigree, which greatly reduces duplication of effort and the potential for error. The use of the software spans all phases of the space system lifecycle, from the study of future concepts to operations and anomaly analysis. It allows SOAP software to correctly position and orient all of the principal bodies of the Solar System within a single simulation session along with multiple spacecraft trajectories and the orientation of mission payloads. In addition to the 3D visualization, the user can define numeric variables and x-y plots to quantitatively assess metrics of interest.

  11. An Operational and Performance Overview of the IRIDIUM Low Earth Orbit Satellite System

    Microsoft Academic Search

    Stephen R. Pratt; Richard A. Raines; Carl E. Fossa Jr.; Michael A. Temple

    1999-01-01

    Today, both the military and commercial sectors are placing an increased emphasis on global communications. This has prompted the development of several low earth orbit satellite systems that promise worldwide connectivity and real-time voice communications. This article provides a tutorial overview of the IRIDIUM low earth orbit satellite system and performance results obtained via simulation. First, it presents an overview

  12. Circumnutations of Sunflower Hypocotyls in Satellite Orbit 1

    PubMed Central

    Brown, Allan H.; Chapman, David K.; Lewis, Robert F.; Venditti, Allen L.

    1990-01-01

    The principal objective of the research reported here was to determine whether a plant's periodic growth oscillations, called circumnutations, would persist in the absence of a significant gravitational or inertial force. The definitive experiment was made possible by access to the condition of protracted near weightlessness in an earth satellite. The experiment, performed during the first flight of Spacelab on the National Aeronautics and Space Administration shuttle, Columbia, in November and December, 1983, tested a biophysical model, proposed in 1967, that might account for circumnutation as a gravity-dependent growth response. However, circumnutations were observed in microgravity. They continued for many hours without stimulation by a significant g-force. Therefore, neither a gravitational nor an inertial g-force was an absolute requirement for initation or continuation of circumnutation. On average, circumnutation was significantly more vigorous in satellite orbit than on earth-based clinostats. Therefore, at least for sunflower (Helianthus annuus L.) circumnutation, clinostatting is not the functional equivalent of weightlessness. PMID:11537478

  13. Expressions Module for the Satellite Orbit Analysis Program

    NASA Technical Reports Server (NTRS)

    Edmonds, Karina

    2008-01-01

    The Expressions Module is a software module that has been incorporated into the Satellite Orbit Analysis Program (SOAP). The module includes an expressions- parser submodule built on top of an analytical system, enabling the user to define logical and numerical variables and constants. The variables can capture output from SOAP orbital-prediction and geometric-engine computations. The module can combine variables and constants with built-in logical operators (such as Boolean AND, OR, and NOT), relational operators (such as >, <, or =), and mathematical operators (such as addition, subtraction, multiplication, division, modulus, exponentiation, differentiation, and integration). Parentheses can be used to specify precedence of operations. The module contains a library of mathematical functions and operations, including logarithms, trigonometric functions, Bessel functions, minimum/ maximum operations, and floating- point-to-integer conversions. The module supports combinations of time, distance, and angular units and has a dimensional- analysis component that checks for correct usage of units. A parser based on the Flex language and the Bison program looks for and indicates errors in syntax. SOAP expressions can be built using other expressions as arguments, thus enabling the user to build analytical trees. A graphical user interface facilitates use.

  14. GBT Reveals Satellite of Milky Way in Retrograde Orbit

    NASA Astrophysics Data System (ADS)

    2003-05-01

    New observations with National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) suggest that what was once believed to be an intergalactic cloud of unknown distance and significance, is actually a previously unrecognized satellite galaxy of the Milky Way orbiting backward around the Galactic center. Path of Complex H Artist's rendition of the path of satellite galaxy Complex H (in red) in relation to the orbit of the Sun (in yellow) about the center of the Milky Way Galaxy. The outer layers of Complex H are being stripped away by its interaction with the Milky Way. The hydrogen atmosphere (in blue) is shown surrounding the visible portion (in white) of the Galaxy. CREDIT: Lockman, Smiley, Saxton; NRAO/AUI Jay Lockman of the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, discovered that this object, known as "Complex H," is crashing through the outermost parts of the Milky Way from an inclined, retrograde orbit. Lockman's findings will be published in the July 1 issue of the Astrophysical Journal, Letters. "Many astronomers assumed that Complex H was probably a distant neighbor of the Milky Way with some unusual velocity that defied explanation," said Lockman. "Since its motion appeared completely unrelated to Galactic rotation, astronomers simply lumped it in with other high velocity clouds that had strange and unpredictable trajectories." High velocity clouds are essentially what their name implies, fast-moving clouds of predominately neutral atomic hydrogen. They are often found at great distances from the disk of the Milky Way, and may be left over material from the formation of our Galaxy and other galaxies in our Local Group. Over time, these objects can become incorporated into larger galaxies, just as small asteroids left over from the formation of the solar system sometimes collide with the Earth. Earlier studies of Complex H were hindered because the cloud currently is passing almost exactly behind the outer disk of the Galaxy. The intervening dust and gas that reside within the sweeping spiral arms of the Milky Way block any visible light from this object from reaching the Earth. Radio waves, however, which have a much longer wavelength than visible light, are able to pass through the intervening dust and gas. The extreme sensitivity of the recently commissioned GBT allowed Lockman to clearly map the structure of Complex H, revealing a dense core moving on an orbit at a 45-degree angle to the plane of the Milky Way. Additionally, the scientist detected a more diffuse region surrounding the central core. This comparatively rarefied region looks like a tail that is trailing behind the central mass, and is being decelerated by its interaction with the Milky Way. "The GBT was able to show that this object had a diffuse 'tail' trailing behind, with properties quite different from its main body," said Lockman. "The new data are consistent with a model in which this object is a satellite of the Milky Way in an inclined, retrograde orbit, whose outermost layers are currently being stripped away in its encounter with the Galaxy." These results place Complex H in a small club of Galactic satellites whose orbits do not follow the rotation of the rest of the Milky Way. Among the most prominent of these objects are the Magellanic Clouds, which also are being affected by their interaction with the Milky Way, and are shedding their gas in a long stream. Since large galaxies, like the Milky Way, form by devouring smaller galaxies, clusters of stars, and massive clouds of hydrogen, it is not unusual for objects to be pulled into orbit around the Galaxy from directions other than that of Galactic rotation. "Astronomers have seen evidence that this accreting material can come in from wild orbits," said Butler Burton, an astronomer with the NRAO in Charlottesville, Virginia. "The Magellanic clouds are being torn apart from their interaction with the Milky Way, and there are globular clusters rotating the wrong way. There is ev

  15. The High-ORbit Ultraviolet-visible Satellite, HORUS

    NASA Astrophysics Data System (ADS)

    Scowen, Paul A.; Cooke, Brian; Beasley, Matthew; Siegmund, Oswald

    2013-09-01

    The High-ORbit Ultraviolet-visible Satellite (HORUS) is a 2.4-meter class space telescope that will conduct a comprehensive and systematic study of the astrophysical processes and environments relevant for the births and life cycles of stars and their planetary systems, to investigate and understand the range of environments, feedback mechanisms, and other factors that most affect the outcome of the star and planet formation process. HORUS will provide 100× greater imaging efficiency and combines the resolution of STIS with the throughput of COS. The HORUS mission will contribute vital information on how solar systems form and whether habitable planets should be common or rare. It also will investigate the structure, evolution, and destiny of galaxies and the universe. This program relies on focused capabilities unique to space that no other planned NASA mission will provide: near-ultraviolet (UV)/visible (200-1100nm) wide-field (14' square), diffraction-limited imaging; and high-sensitivity, high-resolution FUV (100- 320nm) spectroscopy. From its baseline orbit at L2 HORUS will enjoy a stable environment for thermal and pointing control, and long-duration target visibility. The core HORUS design will provide wide field of view imagery and high efficiency point source far-ultraviolet (FUV) spectroscopy using a combination of spectral selection and field sharing.

  16. An overview of in-orbit radiometric calibration of typical satellite sensors

    NASA Astrophysics Data System (ADS)

    Zhou, G. Q.; Li, C. Y.; Yue, T.; Jiang, L. J.; Liu, N.; Sun, Y.; Li, M. Y.

    2015-06-01

    This paper reviews the development of in-orbit radiometric calibration methods in the past 40 years. It summarizes the development of in-orbit radiometric calibration technology of typical satellite sensors in the visible/near-infrared bands and the thermal infrared band. Focuses on the visible/near-infrared bands radiometric calibration method including: Lamp calibration and solar radiationbased calibration. Summarizes the calibration technology of Landsat series satellite sensors including MSS, TM, ETM+, OLI, TIRS; SPOT series satellite sensors including HRV, HRS. In addition to the above sensors, there are also summarizing ALI which was equipped on EO-1, IRMSS which was equipped on CBERS series satellite. Comparing the in-orbit radiometric calibration technology of different periods but the same type satellite sensors analyzes the similarities and differences of calibration technology. Meanwhile summarizes the in-orbit radiometric calibration technology in the same periods but different country satellite sensors advantages and disadvantages of calibration technology.

  17. Response initiated multiple access (RIMA), a medium access control protocol for satellite channels

    Microsoft Academic Search

    D. P. Conners; Gregory J. Pottie

    2000-01-01

    The means of achieving full duplex broadband access to either the home or office has been the focus of much research and entrepreneurial development in the past 5 years. This is the so-called “last mile” problem. One approach is duplex access to either a geostationary Earth orbit (GEO) or non-GSO satellite, through a relatively small satellite dish located at each

  18. GPS satellite-to-satellite tracking for TOPEX\\/Poseidon precise orbit determination and gravity field model improvement

    Microsoft Academic Search

    P. Schwintzer; Z. Kang; Ch. Reigber; S. Y. Zhu

    1995-01-01

    Satellite-to-satellite tracking (SST) between the high-altitude GPS satellites and a low-flying spacecraft, was realized for geodetic applications with the American\\/French altimeter mission TOPEX\\/Poseidon. This tracking scenario has already been tested by experimental GPS receivers with reduced performance on Landsat-4 and Landsat-5 some 10 years ago. Because of its capability to provide continuous data coverage, GPS space-based tracking for precise orbit

  19. Satellite orbit determination using triple-differenced GPS carrier phase in pure kinematic mode

    Microsoft Academic Search

    S. H. Byun

    2003-01-01

    .  ?A new algorithm and computer program, KODAC (Kinematic Orbit Determination And Comparison), was developed for precise satellite\\u000a orbit determination using a kinematic approach with the ionospheric-free triple-differenced (TD) global positioning system\\u000a (GPS) carrier phase as the main observable. Epoch-by-epoch satellite positions are estimated by assuming that the GPS satellite\\u000a ephemerides, ground station positions, and the time series of wet tropospheric

  20. Impact of improved models for precise orbits of altimetry satellites on the orbit accuracy and regional mean sea level trends

    NASA Astrophysics Data System (ADS)

    Rudenko, Sergei; Esselborn, Saskia; Dettmering, Denise; Schöne, Tilo; Neumayer, Karl-Hans

    2015-04-01

    Precise orbits of altimetry satellites are a prerequisite for investigations of global and regional sea level changes. We show a significant progress obtained in the recent decades in modeling and determination of the orbits of altimetry satellites. This progress was reached due to the improved knowledge of the Earth gravity field obtained by using CHAMP (CHAllenging Mini-Satellite Payload), GRACE (Gravity Recovery and Climate Experiment) and GOCE (Gravity field and Ocean Circulation Explorer) data, improved realizations of the terrestrial and celestial reference frames and transformations between these reference frames, improved modeling of ocean and solid Earth tides, improved accuracy of observations and other effects. New precise orbits of altimetry satellites ERS-1 (1991-1996), TOPEX/Poseidon (1992-2005), ERS-2 (1995-2006), Envisat (2002-2012) and Jason-1 (2002-2012) have been recently derived at the time intervals given within the DFG UHR-GravDat project and the ESA Climate Change Initiative Sea Level project using satellite laser ranging (SLR), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), Precise Range And Range-Rate Equipment (PRARE) and altimetry single-satellite crossover data (various observation types were used for various satellites). We show the current state of the orbit accuracy and the improvements obtained in the recent years. In particular, we demonstrate the impact of recently developed time-variable Earth gravity field models, improved tropospheric refraction models for DORIS observations, latest release 05 of the atmosphere-ocean dealiasing product (AOD1B) and some other models on the orbit accuracy of these altimetry satellites and regional mean sea level trends computed using these new orbit solutions.

  1. Variable data rate modem for low Earth orbiting satellite (LEOS) communication

    Microsoft Academic Search

    C. H. Lee

    1995-01-01

    There is wide interest in providing mobile satellite services (MSS) via low Earth orbiting satellite (LEOS) instead of by the traditional geosynchronous satellites (GEOS). This development conforms with the trends in personal communication services (PCS) where low cost, low power and high volume users are the goals. The distinct features of LEOS are characterized by its low altitude (4000 km

  2. Impact of satellite constellation arrangement on the future orbital debris environment

    Microsoft Academic Search

    Shin-Yi Su

    1997-01-01

    The proposed concept of communication satellite constellation such as Iridium (with 66 satellites) and Teledesic (with 840 satellites) in LEO has been studied for its operational constrains and the impact to the evolution of the future orbital debris environment. A large number of spacecraft in constellation creates a spike in spatial density distribution at a place where they are collocated

  3. Flight Mechanics/Estimation Theory Symposium. [with application to autonomous navigation and attitude/orbit determination

    NASA Technical Reports Server (NTRS)

    Fuchs, A. J. (editor)

    1979-01-01

    Onboard and real time image processing to enhance geometric correction of the data is discussed with application to autonomous navigation and attitude and orbit determination. Specific topics covered include: (1) LANDSAT landmark data; (2) star sensing and pattern recognition; (3) filtering algorithms for Global Positioning System; and (4) determining orbital elements for geostationary satellites.

  4. Thermospheric density variations: Observability using precision satellite orbits and effects on orbit propagation

    NASA Astrophysics Data System (ADS)

    Lechtenberg, Travis; McLaughlin, Craig A.; Locke, Travis; Krishna, Dhaval Mysore

    2013-01-01

    paper examines atmospheric density estimated using precision orbit ephemerides (POE) from the CHAMP and GRACE satellites during short periods of greater atmospheric density variability. The results of the calibration of CHAMP densities derived using POEs with those derived using accelerometers are examined for three different types of density perturbations, [traveling atmospheric disturbances (TADs), geomagnetic cusp phenomena, and midnight density maxima] in order to determine the temporal resolution of POE solutions. In addition, the densities are compared to High-Accuracy Satellite Drag Model (HASDM) densities to compare temporal resolution for both types of corrections. The resolution for these models of thermospheric density was found to be inadequate to sufficiently characterize the short-term density variations examined here. Also examined in this paper is the effect of differing density estimation schemes by propagating an initial orbit state forward in time and examining induced errors. The propagated POE-derived densities incurred errors of a smaller magnitude than the empirical models and errors on the same scale or better than those incurred using the HASDM model.

  5. Cosmic Ménage à Trois: The Origin of Satellite Galaxies On Extreme Orbits

    E-print Network

    L. V. Sales; J. F. Navarro; M. G. Abadi; M. Steinmetz

    2007-05-24

    We examine the orbits of satellite galaxies identified in a suite of N-body/gasdynamical simulations of the formation of $L_*$ galaxies in a LCDM universe. Most satellites follow conventional orbits; after turning around, they accrete into their host halo and settle on orbits whose apocentric radii are steadily eroded by dynamical friction. However, a number of outliers are also present, we find that ~1/3 of satellites identified at $z=0$ are on unorthodox orbits, with apocenters that exceed their turnaround radii. This population of satellites on extreme orbits consists typically of the faint member of a satellite pair that has been ejected onto a highly-energetic orbit during its first approach to the primary. Since the concurrent accretion of multiple satellite systems is a defining feature of hierarchical models of galaxy formation, we speculate that this three-body ejection mechanism may be the origin of (i) some of the newly discovered high-speed satellites around M31 (such as Andromeda XIV); (ii) some of the distant fast-receding Local Group members, such as Leo I; and (iii) the oddly isolated dwarf spheroidals Cetus and Tucana in the outskirts of the Local Group. Our results suggest that care must be exercised when using the orbits of the most weakly bound satellites to place constraints on the total mass of the Local Group.

  6. Generalized Split-Window Algorithm for Estimate of Land Surface Temperature from Chinese Geostationary FengYun Meteorological Satellite (FY-2C) Data

    PubMed Central

    Tang, Bohui; Bi, Yuyun; Li, Zhao-Liang; Xia, Jun

    2008-01-01

    On the basis of the radiative transfer theory, this paper addressed the estimate of Land Surface Temperature (LST) from the Chinese first operational geostationary meteorological satellite-FengYun-2C (FY-2C) data in two thermal infrared channels (IR1, 10.3-11.3 ?m and IR2, 11.5-12.5 ?m), using the Generalized Split-Window (GSW) algorithm proposed by Wan and Dozier (1996). The coefficients in the GSW algorithm corresponding to a series of overlapping ranging of the mean emissivity, the atmospheric Water Vapor Content (WVC), and the LST were derived using a statistical regression method from the numerical values simulated with an accurate atmospheric radiative transfer model MODTRAN 4 over a wide range of atmospheric and surface conditions. The simulation analysis showed that the LST could be estimated by the GSW algorithm with the Root Mean Square Error (RMSE) less than 1 K for the sub-ranges with the Viewing Zenith Angle (VZA) less than 30° or for the sub-rangs with VZA less than 60° and the atmospheric WVC less than 3.5 g/cm2 provided that the Land Surface Emissivities (LSEs) are known. In order to determine the range for the optimum coefficients of the GSW algorithm, the LSEs could be derived from the data in MODIS channels 31 and 32 provided by MODIS/Terra LST product MOD11B1, or be estimated either according to the land surface classification or using the method proposed by Jiang et al. (2006); and the WVC could be obtained from MODIS total precipitable water product MOD05, or be retrieved using Li et al.' method (2003). The sensitivity and error analyses in term of the uncertainty of the LSE and WVC as well as the instrumental noise were performed. In addition, in order to compare the different formulations of the split-window algorithms, several recently proposed split-window algorithms were used to estimate the LST with the same simulated FY-2C data. The result of the intercomparsion showed that most of the algorithms give comparable results.

  7. From Measurements to Models: What Satellite and Sub-Orbital Instruments

    E-print Network

    From Measurements to Models: What Satellite and Sub-Orbital Instruments Can and Must Contribute km MISR Stereo-Derived Plume Heights 07 May 2010 Orbit 55238 Path 216 Blk 40 UT 12:39 km 0 2 4 6 Plume 1 Plume 2 #12;D. Nelson and the MISR Team MISR Stereo-Derived Plume Heights 07 May 2010 Orbit

  8. Energy integral method for gravity field determination from satellite orbit coordinates

    Microsoft Academic Search

    P. N. A. M. Visser; N. Sneeuw; C. Gerlach

    2003-01-01

    A fast iterative method for gravity field determination from low Earth satellite orbit coordinates has been developed and implemented successfully. The method is based on energy conservation and avoids problems related to orbit dynamics and initial state. In addition, the particular geometry of a repeat orbit is exploited by using a very efficient iterative estimation scheme, in which a set

  9. PERSONAL HAND-HELD COMMUNICATIONS VIA L-BAND CDMA-BASED GEOSTATIONARY BEAMFORMING

    E-print Network

    Blostein, Steven D.

    PERSONAL HAND-HELD COMMUNICATIONS VIA L-BAND CDMA-BASED GEOSTATIONARY BEAMFORMING SATELLITES. The goal of this thesis is to investigate the feasi- blilty of utilizing a CDMA-based, L-band-based geostationary satellite with on-board processing is proposed. The satellite transmits and receives signals at L-band

  10. Very long baseline interferometry observations using the tracking and data relay satellite as an orbiting radio telescope

    NASA Technical Reports Server (NTRS)

    Linfield, R. P.; Levy, G. S.; Ulvestad, J. S.; Edwards, C. D.; Jordan, J. F., Jr.; Dinardo, S. J.; Christensen, C. S.; Preston, R. A.; Skjerve, L. J.; Blaney, K. B.

    1988-01-01

    An antenna in geostationary orbit was used for VLBI observations at 2.3 GHz, in combination with ground antennas in Australia and Japan. 23 of the 25 observed sources were detected on orbiter-ground baselines, with baseline lengths as large as 2.15 earth diameters. Brightness temperatures between 10 to the 12th K and 4 x 10 to the 12th K were measured for 10 sources.

  11. Q2 Consider the motion of a satellite of mass m in orbit about a much more massive planet.

    E-print Network

    Ha, Taekjip

    Q2 Consider the motion of a satellite of mass m in orbit about a much more massive planet. a) Use changing its magnitude. As shown in the figure, this makes the satellite enter an elliptical orbit as that of the circular orbit. c) Find vperiapsis, the velocity of the satellite at closest approach to the planet. d

  12. Space Systems Field Exam Consider a satellite in low Earth, circular orbit with altitude h and period To. The

    E-print Network

    de Weck, Olivier L.

    Space Systems Field Exam Consider a satellite in low Earth, circular orbit with altitude h. 1. Assume that the orbit is such that the satellite is always illuminated by the Sun mass power sub-system? 2. Assume that the orbit is such that the satellite experiences an eclipse each

  13. The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS): A Canadian Mission to the Inner Magnetosphere

    Microsoft Academic Search

    I. R. Mann; T. Loto'Aniu; D. K. Milling; R. Rankin; R. Fedosejevs; Y. Y. Tsui; D. Knudsen; A. Yau; K. Balmain; D. McCabe; D. N. Baker; J. R. Wygant; J. F. Fennel; L. Kistler; G. Reeves

    2006-01-01

    The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission is proposed as a Canadian Space Agency satellite mission contribution to ILWS. The ORBITALS is currently approved by the CSA for Phase A, and the NASA LWS Mission of Opportunity 4-instrument payload MORE (Mission of Opportunity Radbelt Experiment) for the ORBITALS satellite is undergoing NASA funded Phase A

  14. Advanced geostationary radar for hurricane monitoring and studies

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Durden, Stephen L.; Rahmat-Samii, Yahya; Fang, Houfei; Cable, Vaughn; Lou, Michael; Huang, John

    2004-01-01

    The current Geostationary Operational Environmental Satellites (GOES) are equipped to make cloud top measurements only. In contrast, a millimeter-wave radar allows 3-D measurements of precipitation associated with hurricanes and other convective systems.

  15. GPS satellite-to-satellite tracking for TOPEX/Poseidon precise orbit determination and gravity field model improvement

    NASA Astrophysics Data System (ADS)

    Schwintzer, P.; Kang, Z.; Reigber, Ch.; Zhu, S. Y.

    1995-10-01

    Satellite-to-satellite tracking (SST) between the high-altitude GPS satellites and a low-flying spacecraft, was realized for geodetic applications with the American/French altimeter mission TOPEX/Poseidon. This tracking scenario has already been tested by experimental GPS receivers with reduced performance on Landsat-4 and Landsat-5 some 10 years ago. Because of its capability to provide continuous data coverage, GPS space-based tracking for precise orbit restitution is superior to any ground-based tracking system. To investigate the accuracy potential offered by this observation system, the EPOS (Earth Parameter and Orbit System) software of GFZ Potsdam was extended to process GPS-SST data for precise TOPEX/Poseidon orbit determination and gravity field model improvement. The used observations are undifferenced pseudo-ranges and carrier phases as obtained from the on-board GPS receiver. In a two step approach the dynamic orbit determination method is applied with the precomputed ephemerides and clock parameters of the GPS satellites introduced as fixed parameters. The comparisons with precise TOPEX/Poseidon orbits computed by JPL in a different approach but using the same observations, and those computed by CNES/GRGS from DORIS-doppler and laser tracking data, reveal a homogeneous radial orbit consistency of about 3 cm and a total agreement of the adjusted satellite positions from different solutions within 12 cm. GPS-SST data covering one TOPEX/Poseidon orbit repeat cycle (10 days) are then incorporated into the normal equation system of the GRIM4 global gravity field model. As predictable from the very small observation residuals in the orbit adjustments, the contribution of this data set to the overall quality of the GRIM4 model is perceivable but not very significant, due to the relatively large altitude of the satellite.

  16. Precise orbit determination of DORIS satellites: comparison of reduced-dynamical and dynamical orbit modeling and the verification of the nominal satellite models

    NASA Astrophysics Data System (ADS)

    Stepanek, P.; Rodriguez-Solano, C.; Hugentobler, U.; Filler, V.

    2012-12-01

    The reduced-dynamical modeling is currently used by the routine solutions of the GOP analysis center, which allows to a similar accuracy as the other analysis centers utilizing a precise non-conservative force modeling. The GOP works with a modified version of the Bernese GPS Software that doesn`t include the modeling of non-conservative forces but uses an empirical and pseudo-stochastic orbit modeling. This limitation is now overcome by the new scientific modification of the software, which opens the unique possibility to apply both approaches using the same software platform. The precise dynamical LEO orbit modeling includes the nominal attitude models and the satellite macro-models, which interact with the solar radiation, the Earth radiation and the atmosphere. The focus of this study is the analysis of the comparison between these two different approaches for LEO satellite orbit determination. Moreover, the need of employing empirical parameters, e.g. once-per-revolution along- and cross-track parameters, will be analyzed to verify the quality of the nominal satellite models. Finally, the impact of increasing complexity models will be discussed. All the presented studies are based on the comparison of estimated DORIS orbits with the multi-technique orbits estimated by other groups as well as on the internal arc overlaps and the orbit validation using SLR data. Not only orbit estimated with fixed network are analyzed but also the impact of the orbit models on the free-network solutions is investigated.

  17. A Permanent Magnet Hall Thruster for Pulsed Orbit Control of Lunar Polar Satellites

    NASA Astrophysics Data System (ADS)

    Silva Moraes, Brunno; Ferreira, José Leonardo; Soares Ferreira, Ivan; Cabo Winter, Othon; Cardozo Mourão, Décio

    2014-05-01

    Future Moon missions devoted to Lunar surface remote sensing, for example, will require very fine and accurate orbit control. It is well known that Lunar satellites in polar orbits will suffer a high increase on the eccentricity due to the gravitational perturbation of the Earth. Without proper orbit correction the satellite lifetime will decrease and end up in a collision with the Moon surface. It is pointed out by many authors that this effect is a natural consequence of the Lidov-Kozai resonance. We studied different arcs of active lunar satellite propulsion, centered on the orbit apoapsis or periapsis, in order to be able to introduce a correction of the eccentricity at each cycle. The proposed method is based on an approach intended to keep the orbital eccentricity of the satellite at low values.

  18. Data catalog series for space science and applications flight missions. Volume 2A: Descriptions of geostationary and high-altitude scientific spacecraft and investigations

    NASA Technical Reports Server (NTRS)

    Hills, H. K. (editor); Littlefield, R. G. (editor); Schofield, N. J. (editor); Vetts, J. I. (editor)

    1982-01-01

    Data from Earth-orbiting spacecraft at geostationary and higher altitudes was cataloged. Three lunar-orbiting spacecraft and some others whose apogees did not attain the geostationary altitude are included.

  19. The National Polar-orbiting Operational Environmental Satellite System: Capabilities for Atmospheric Remote Sensing for NWP and Climate -- Moving Towards a Global Earth Observation System of Systems

    NASA Astrophysics Data System (ADS)

    Mango, S. A.; Hinnant, F.; Hoffman, C. W.; Smehil, D. L.; Schneider, S. R.; Simione, S.; Needham, B.; Stockton, D.

    2005-12-01

    Over the last decade, the tri-agency Integrated Program Office (IPO), comprised of the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA), has been managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Once operational later this decade, NPOESS will replace NOAA's Polar-orbiting Operational Environmental Satellites (POES) and DoD's Defense Meteorological Satellite Program (DMSP) systems. The IPO, through its Acquisition and Operations contractor, Northrop Grumman, will launch NPOESS spacecraft into three orbital planes to provide a single, national system capable of satisfying both civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving the existing "weather" satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - ocean, atmosphere, land, and the space environment. The NPOESS will enable more accurate short-term weather forecasts and severe storm warnings and improved monitoring of atmospheric phenomena. NPOESS will also provide continuity of critical data for monitoring, understanding, and predicting climate change and assessing the impacts of climate change on seasonal and longer time scales. For these purposes, the NPOESS Integrated Program Office [IPO] is developing a suite of advanced, atmospheric sounding/probing instruments as a major part of the next generation meteorological, environmental and climate operational satellite system in polar, low earth orbit [LEO]. The IPO is developing the CrIS, Cross-track Infrared Sounder, an Ozone Mapping & Profiler Suite [OMPS]and a Visible and Infrared Imager and Radiometer Suite [VIIRS] and NASA is developing an Advanced Technology Microwave Sounder [ATMS]. These four instruments will be key parts of the NPOESS operational satellite system and its precursor, bridging and risk-reduction mission - the NPOESS Preparatory Project [NPP]. The CrIS/ATMS/OMPS (& VIIRS) and, later on NPOESS, a Conical-scanning Microwave Imager and Sounder [CMIS] will represent a USA highly capable, complementary sounding and imaging suite for the next generation. In the same time frame the European community, EUMETSAT, European Organization for the Exploitation of Meteorological Satellite Systems, will be flying their next generation, operational, polar-orbiting LEO system, METOP. METOP will have a highly capable FTS sounder, IASI [Infrared Atmospheric Sounder Interferometer], an Advanced Microwave Sounding Unit [AMSU], a Global Ozone Monitoring Experiment [GOME-2], a GNSS Receiver for Atmospheric Sounding [GRAS]and an Advanced Very High Resolution Radiometer [AVHRR]. The NPOESS & METOP sounders and imagers will represent a significant contribution to a polar-orbiting, atmospheric sounding and imaging component of an emerging Global Earth Observation System of Systems [GEOSS] for NWP and Climate. Similarly the Geostationary Operational Environmental Satellite System [GOES-R] & Meteosat Second Generation [MSG] sounders and imagers will represent an important geostationary component of such a GEOSS.

  20. Orbit Adjustment for EROS A1 High Resolution Satellite Images

    Microsoft Academic Search

    Liang-Chien CHEN; Tee-Ann TEO

    As the resolution of satellite images is improving, the applications of satellite images become widespread. Orientation modeling is an indispensable step in the processing for satellite. EROS A1 is a high resolution imaging satellite. Its linear array pushbroom imager is with 1.8meter resolution on ground. EROS A1 is a sun-synchronous satellite and sampling with asynchronous mode. The main purpose of

  1. On possibility of minor body's capture to a satellite orbit before collision with Earth

    NASA Astrophysics Data System (ADS)

    Rosaev, A. E.

    2002-11-01

    In the context of the asteroid's danger problem, the determination of potentially the most dangerous orbits - the orbits of collision with the Earth - has a significant interest. One kind of orbit of collision is related with Lagrangian libration solution for the three body problem. It is known, that possible (temporary) capture to a satellite orbit from orbit near libration point. In case captured orbit has large inclination, it has very fast eccentricity evolution (increasing), leads to inevitable collision. It is not excepted, that object, caused ecological catastrophe 40 mln. years ago, and object push with the Earth on the border Mesozoic and Cenozoic era before the collision were move on of the Earth's satellite orbit. The example of this kind of orbit of collision is presented in this work.

  2. Surveillance of medium and high Earth orbits using large baseline stereovision

    NASA Astrophysics Data System (ADS)

    Danescu, Radu; Ciurte, Anca; Oniga, Florin; Cristea, Octavian; Dolea, Paul; Dascal, Vlad; Turcu, Vlad; Mircea, Liviu; Moldovan, Dan

    2014-11-01

    The Earth is surrounded by a swarm of satellites and associated debris known as Resident Space Objects (RSOs). All RSOs will orbit the Earth until they reentry into Earth's atmosphere. There are three main RSO categories: Low Earth Orbit (LEO), when the satellite orbits at an altitude below 1 500 km; a Medium Earth Orbit (MEO) for Global Navigation Satellite Systems (GNSS) at an altitude of around 20 000 km, and a Geostationary Earth Orbit (GEO) (also sometimes called the Clarke orbit), for geostationary satellites, at an altitude of 36 000 km. The Geostationary Earth Orbits and the orbits of higher altitude are also known as High Earth Orbits (HEO). Crucial for keeping an eye on RSOs, the Surveillance of Space (SofS) comprises detection, tracking, propagation of orbital parameters, cataloguing and analysis of these objects. This paper presents a large baseline stereovision based approach for detection and ranging of RSO orbiting at medium to high altitudes. Two identical observation systems, consisting of camera, telescope, control computer and GPS receiver are located 37 km apart, and set to observe the same region of the sky. The telescopes are placed on equatorial mounts able to compensate for the Earth's rotation, so that the stars appear stationary in the acquired images, and the satellites will appear as linear streaks. The two cameras are triggered simultaneously. The satellite streaks are detected in each image of the stereo pair using its streak-like appearance against point-like stars, the motion of the streaks between successive frames, and the stereo disparity. The detected satellite pixels are then put into correspondence using the epipolar geometry, and the 3D position of the satellite in the Earth Center, Earth Fixed (ECEF) reference frame is computed using stereo triangulation. Preliminary tests have been performed, for both MEO and HEO orbits. The preliminary results indicate a very high detection rate for MEO orbits, and good detection rate for HEO orbits, dependent on the satellite's rotation.

  3. Regenerative fuel cell study for satellites in GEO orbit

    NASA Astrophysics Data System (ADS)

    Levy, Alexander; Vandine, Leslie L.; Stedman, James K.

    1987-07-01

    Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. The first, the integrated design, utilized a configuration in which the fuel cell and electrolysis cells are alternately stacked inside a pressure vessel. Product water is transferred by diffusion during electrolysis and waste heat is conducted through the pressure wall, thus using completely passive means for transfer and control. The second alkaline system, the dedicated design, uses a separate fuel cell and electrolysis stack so that each unit can be optimized in size and weight based on its orbital operating period. The third design was a dual function stack configuration, in which each cell can operate in both fuel cell and electrolysis mode, thus eliminating the need for two separate stacks and associated equipment. Results indicate that using near term technology energy densities between 46 and 52 W-hr/lb can be achieved at efficiencies of 55 percent. System densities of 115 W-hr/lb are contemplated.

  4. Orbital performance of communication satellite microwave power amplifiers (MPAs)

    NASA Technical Reports Server (NTRS)

    Strauss, R.

    1993-01-01

    This paper presents background data on the performance of microwave power amplifiers (MPAs) used as transmitters in currently operating commercial communication satellites. Specifically aspects of two competing MPA types are discussed. These are well known TWTA (travelling wave tube amplifier) and the SSPA (solid state power amplifier). Extensive in-orbit data has been collected from over 2000 MPAs in 1991 and 1993. The study in 1991 invovlved 75 S/C (spacecraft) covering 463 S/C years. The 1993 'second-look' study encompassed a slightly different population of 72 S/C with 497 S/C years of operation. A surprising result of both studies was that SSPAs, although quite reliable, did not achieve the reliability of TWTAs were one-third more reliable in the 1993 study. This was at C-band with comparable power amplifiers, e.g. 6-16W of RF output power and similar gains. Data at K(sub u)-band is for TWTAs only since there are no SSPAs in the current S/C inventory. The other complementary result was that the projected failure rates used as S/C payload design guidelines were, on average, somewhat higher for TWTAs than the actual failure rates uncovered by this study. SSPA rates were as projected.

  5. The LAGEOS satellites orbital residuals determination and the way to extract gravitational and non-gravitational unmodeled perturbing effects

    Microsoft Academic Search

    D. M. Lucchesi

    2007-01-01

    Long-arc analysis of the orbits of geodetic satellites is a useful way to extract relevant information concerning the Earth structure, as well as to test relativistic gravity in Earth’s surroundings. The physical information is concentrated in the satellite orbital residuals that must be computed from the orbital elements determined during a very precise orbit determination procedure. However, the physical information

  6. The LAGEOS satellites orbital residuals determination and the way to extract gravitational and non-gravitational unmodeled perturbing effects

    Microsoft Academic Search

    D. M. Lucchesi

    2007-01-01

    Long-arc analysis of the orbits of geodetic satellites is a useful way to extract relevant information concerning the Earth structure, as well as to test relativistic gravity in Earth's surroundings. The physical information is concentrated in the satellite orbital residuals that must be computed from the orbital elements determined during a very precise orbit determination procedure. However, the physical information

  7. The LAGEOS satellites orbital residuals determination and the way to extract gravitational and non-gravitational unmodelled perturbing effects

    Microsoft Academic Search

    D. M. Lucchesi

    2006-01-01

    Long-arc analysis of the orbits of geodetic satellites is a useful way to extract relevant information concerning the Earth structure as well as to test relativistic gravity in Earth s surroundings The physical information is concentrated in the satellite orbital residuals that must be extracted from the orbital elements determined during the precise orbit determination procedure However the physical information

  8. The importance of direct readout satellite data in sub-synoptic scale data assimilation and numerical weather prediction

    Microsoft Academic Search

    J. Le Marshall; L. M. Leslie; N. Pescod; C. Spinoso; R. Morison

    1997-01-01

    Observations, directly read out from polar orbiting and geostationary satellites are vital to sub-synoptic scale analysis and forecasting over the Australian Region. Physically based methods are used for determining temperature, moisture and total ozone from NOAA satellite radiance observations from the High Resolution Infrared Sounder (HIRS), Microwave Sounding Unit (MSU) and Solar Backscatter Ultraviolet Radiometer (SBUV\\/2) instruments. Physical methods have

  9. Design and analysis of the satellite laser communications network

    NASA Astrophysics Data System (ADS)

    Ren, Pei-an; Qian, Fengchen; Liu, Qiang; Jin, Linlin

    2015-02-01

    A satellite laser communications network structure with two layers and multiple domains has been proposed, which performance has been simulated by OPENT. To simulation, we design several OPNET models of the network's components based on a satellite constellation with two layers and multiple domains, as network model, node model, MAC layer protocol and optical antenna model. The network model consists of core layer and access layer. The core network consists of four geostationary orbit (GEO) satellites which are uniformly distributed in the geostationary orbit. The access network consists of 6 low Earth orbit (LEO) satellites which is the walker delta (walk-?) constellation with three orbit planes. In access layer, each plane has two satellites, and the constellation is stably. The satellite constellation presented for space laser network can meet the demand of coverage in the middle and low latitude by a few satellites. Also several terminal device models such as the space laser transmitter, receiver, protocol layer module and optical antenna have been designed according to the inter-satellite links in different orbits t from GEO to LEO or GEO to ground. The influence to network of different transmitting throughput, receiving throughput, network protocol and average time delay are simulated. Simulation results of network coverage, connectivity and traffic load performance in different scenes show that the satellite laser network presented by the paper can be fit for high-speed satellite communications. Such analysis can provide effective reference for the research of satellite laser networking and communication protocol.

  10. Introduction to satellite constellations orbital types, uses and related facts

    E-print Network

    Wood, Lloyd

    . #12;Tundra Useful highly elliptical orbits (HEO) Yellow circular GEO orbit shown for scale · Molnya (0.5sd ~12hr) and Tundra (~24hr 1sd orbits) ­ cover high latitudes at apogee. · Invented by Soviet) and Tundra (~24hr 1sd orbits) ­ cover high latitudes at apogee. · Invented by Soviet military; then Russian

  11. Precise orbit determination of low-earth satellites using SST data

    NASA Astrophysics Data System (ADS)

    Kang, Z.; Schwintzer, P.; Reigber, Ch.; Zhu, S. Y.

    The Satellite-to-Satellite Tracking (SST) in the high-low and/or low-low configuration is presently considered as being the most promising method for precise orbit determination and global gravity field recovery. Particularly, the use of the GPS system for orbit determination in the high-low configuration has been extensively studied and successfully tested on TOPEX/Poseidon. Recently, many space missions (e.g. CHAMP, STEP) have shown increased interest in implementing GPS-based orbit determination schemes. The along track orbit accuracy in high-low case is not good. To improve this accuracy, we have investigated the orbit determination using both the high-low SST observations between GPS and low-Earth satellites and the low-low SST observations between low-Earth satellites. The study and analyses are based on a deterministic simulation approach. The simulated data between GPS and low-Earth satellites are carrier phases and pseudoranges. The range and range rate between low-Earth satellite are simulated. This paper presents results of an orbit determination study for satellites at 500 km altitude as an example.

  12. Prototype Development of a Geostationary Synthetic Thinned Aperture Radiometer, GeoSTAR

    NASA Technical Reports Server (NTRS)

    Tanner, Alan B.; Wilson, William J.; Kangaslahti, Pekka P.; Lambrigsten, Bjorn H.; Dinardo, Steven J.; Piepmeier, Jeffrey R.; Ruf, Christopher S.; Rogacki, Steven; Gross, S. M.; Musko, Steve

    2004-01-01

    Preliminary details of a 2-D synthetic aperture radiometer prototype operating from 50 to 58 GHz will be presented. The instrument is being developed as a laboratory testbed, and the goal of this work is to demonstrate the technologies needed to do atmospheric soundings with high spatial resolution from Geostationary orbit. The concept is to deploy a large sparse aperture Y-array from a geostationary satellite, and to use aperture synthesis to obtain images of the earth without the need for a large mechanically scanned antenna. The laboratory prototype consists of a Y-array of 24 horn antennas, MMIC receivers, and a digital cross-correlation sub-system. System studies are discussed, including an error budget which has been derived from numerical simulations. The error budget defines key requirements, such as null offsets, phase calibration, and antenna pattern knowledge. Details of the instrument design are discussed in the context of these requirements.

  13. Precise orbit determination for the FORMOSAT-3/COSMIC satellite mission using GPS

    NASA Astrophysics Data System (ADS)

    Hwang, Cheinway; Tseng, Tzu-Pang; Lin, Tingjung; Švehla, Dražen; Schreiner, Bill

    2009-05-01

    The joint Taiwan-US mission FORMOSAT-3/ COSMIC (COSMIC) was launched on April 17, 2006. Each of the six satellites is equipped with two POD antennas. The orbits of the six satellites are determined from GPS data using zero-difference carrier-phase measurements by the reduced dynamic and kinematic methods. The effects of satellite center of mass (COM) variation, satellite attitude, GPS antenna phase center variation (PCV), and cable delay difference on the COSMIC orbit determination are studied. Nominal attitudes estimated from satellite state vectors deliver a better orbit accuracy when compared to observed attitude. Numerical tests show that the COSMIC COM must be precisely calibrated in order not to corrupt orbit determination. Based on the analyses of the 5 and 6-h orbit overlaps of two 30-h arcs, orbit accuracies from the reduced dynamic and kinematic solutions are nearly identical and are at the 2-3 cm level. The mean RMS difference between the orbits from this paper and those from UCAR (near real-time) and WHU (post-processed) is about 10 cm, which is largely due to different uses of GPS ephemerides, high-rate GPS clocks and force models. The kinematic orbits of COSMIC are expected to be used for recovery of temporal variations in the gravity field.

  14. Deriving Atmospheric Density Estimates Using Satellite Precision Orbit Ephemerides

    E-print Network

    Hiatt, Andrew Timothy

    2009-01-01

    GSFC Goddard Space Flight Center HASDM High Accuracy Satellite Drag Model ICESat Ice, Cloud, and Land Elevation Satellite MSISE Mass Spectrometer Incoherent Scatter Extending from ground to space MUV Middle Ultra-Violet NASA National...

  15. Developing the concept of a geostationary platform. [for communication services

    NASA Technical Reports Server (NTRS)

    Carey, W. T.; Bowman, R. M.; Stone, G. R.

    1980-01-01

    A geostationary platform concept with a proliferation of low-cost earth stations is discussed. Candidate platform concepts, servicing, life, and Orbital Transfer Vehicle (OTV) options are considered. A Life Cycle Costing model is used to select the minimum cost concept meeting program criteria. It is concluded that the geostationary platform concept is a practical and economical approach to providing expanding communication services within the limitations imposed by the available frequency spectrum and orbital arc.

  16. An experimental optical link between an earth remote sensing satellite, SPOT 4, and a European data relay satellite

    Microsoft Academic Search

    M. Arnaud; A. Barumchercyk; E. Sein

    1988-01-01

    The implementation of an experimental optical link between a low earth orbit spacecraft (SPOT 4) and a geostationary satellite (for which ESA is responsible) is described. This optical link is to be used for transmitting the SPOT 4 payload data stream at a rate of 50 Mb\\/s. These data will be relayed to a ground station through a feeder link

  17. Flyaround Maneuvers on a Satellite Orbit by Impulsive Thrust Control

    Microsoft Academic Search

    Yasuhiro Masutani; Motoshi Matsushita; Fumio Miyazaki

    2001-01-01

    Close circumnavigation is an important function indispensable for servicing satellites. We discuss the bielliptic flyaround maneuver by impulsive thrust control for a small and low cost servicing satellite flying around a target satellite. An optimal feedback control scheme for the thrust is proposed to maintain this trajectory in the presence of disturbances. The extended Kalman filter is employed to estimate

  18. Experiment definition phase shuttle laboratory (LDRL-10.6 experiment): Shuttle sortie to elliptical orbit satellite

    NASA Technical Reports Server (NTRS)

    Goodwin, F. E.; Nussmeier, T. A.; Stokes, L. S.; Vourgourakis, E. J.

    1976-01-01

    The following topics were reviewed: (1) design options for shuttle terminal, (2) elliptical orbit satellite design options, (3) shuttle terminal details, (4) technology status and development requirements, (5) transmitter technology, and (6) carbon dioxide laser life studies.

  19. A Stereoscopic Technique to Estimate Cloud-Top Height Using Combined Geostationary and Low Earth Orbiting Satellites

    Microsoft Academic Search

    Veenhuis Bruce Albert Jr

    2009-01-01

    Accurate knowledge of cloud-top height is important for a range of meteorological applications. Uses include cloud classification and the assignment of height levels to cloud drift winds. Such data may also be useful for monitoring tropical cyclone intensity over observation sparse oceans. A new method to retrieve cloud-top height has been developed in order to improve the temporal and spatial

  20. a Discussion on the Hazards on the EMBRATEL's (Star One) Satellites and Others in the Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Martins Nascimento, Jorge

    A mass observed with a piezoelectric element is discussed using hypervelocity particles accel-erated by the Van de Graaff accelerator. Since the response of the PZT element is velocity-dependent, the particle mass can be derived using calibration formulas that depend on the velocity. When the velocity during collision exceeds 20 km/s, the piezoelectric element produces a pulsed signal. Then, the rise time and the amplitude of the pulsed signal are well correlated. If the rise time and the amplitude are measured pair off, the response to the collision is classified into three groups [1]. If the calibration formulas can be established in each group, the mass is determined. Let define the deviation by (1) (mm-m0)/m0 (1) where mm is the mass value obtained using the calibration formulas of each group and m0 is that by the time of flight method, respectively. The deviation distributes like a Gaussian form. The mass can be reproduced within 40 When the velocity is less than 10 km/s, the output is of a characteristic form, with which the collision time is exactly determined. The amplitude is subject not only to the particle momentum p but also to the charge q of particle. Then, the PZT element is sensitive to q before the particle arrives at the element during flight time t, if q ? 50 fC. Since the sensitive distance d is calibrated with respect to q, the velocity v and the mass m are obtained; v = d /t, and m = p/v. The deviation defined by (1) distributes like a Gaussian form. The mass can be reproduced described above. Reference [1] T.Miyachi et al., submitted for publication in Adv. Space Res.

  1. Sampling uncertainty in satellite rainfall estimates

    NASA Astrophysics Data System (ADS)

    Itkin, M.; Loew, A.

    2012-04-01

    Accurate estimates of global precipitation patterns are essential for a better understanding of the hydrological cycle. Satellite observations allow for large scale estimates of rainfall intensities. Uncertainties in current satellite based rainfall estimates are due to uncertainties in the retrieval process as well as the different temporal and spatial sampling patterns of the observation systems. The focus of this study is set on analyzing sampling associated uncertainty for thirteen low Earth orbiting satellites carrying microwave instruments suitable for rainfall measurement. Satellites were grouped by the types of microwave sensors, where NOAA satellites with cross-track sounders and DMSP satellites with conical scanners make the core part of the constellations. The effect of three hourly geostationary measurements on the sampling uncertainty was evaluated as well. A precise orbital model SGP4 was used to generate realistic satellite overpasses database where orbital shifts are taken into account. Using the overpasses database we resampled rain gauge timeseries to simulate satellites rainfall estimates free of retrieval and calibration errors. We look at two regions, Germany and Benin, areas with different precipitation regimes . Our analysis show that sampling uncertainty for all available satellites may differ up to 100% for different latitudes and precipitation regimes. However the performance of various satellite groups is similar to each other, with greater differences in higher latitudes. Addition of three hourly geostationary observations reduces the sampling uncertainty but only to a limited extent.

  2. Satellite orbit estimation using DORIS data: comparison of reduced-dynamic and dynamic orbit modeling and discussion of modeling aspects

    NASA Astrophysics Data System (ADS)

    Stepanek, Petr; Rodriguez-Solano, Carlos; Filler, Vratislav; Hugentobler, Urs

    2013-04-01

    Reduced-dynamic orbit modeling is currently used to compute the routine solutions of the GOP analysis center, which are of similar accuracy as solutions from the other centers utilizing a precise non-conservative force modeling. GOP works with a modified version of the Bernese GPS Software that has not supported non-conservative orbit modeling but utilized empirical and pseudo-stochastic orbit modeling. This limitation is now overcome by new scientific modification of the software, which opens the unique possibility to compare both approaches using the same software platform. The precise dynamic LEO orbit modeling includes the attitude models and the nominal satellite macro-models, with modeling of non-conservative acceleration, i.e., Sun radiation pressure, Earth radiation pressure and atmospheric drag. Both dynamic and reduced-dynamic approaches are used by different analysis centers providing DORIS solutions. The focus of this study is the analysis of the differences between these two approaches for LEO satellite orbit estimation and the verification of the nominal satellite attitude model quality, checked through the necessity of employing 1-per revolution empirical parameters. In addition, the impact of indirect and direct Earth radiation pressure models are assessed, including an analytical model as well as a latitude dependent and a latitude-longitude dependent model. All the presented studies are based on the comparison of estimated DORIS orbits with the multi-technique orbits estimated by other groups as well as on internal arc overlaps and orbit validation using SLR data. Not only orbits estimated with fixed network are analyzed but also the impact of the orbital models on the free-network solutions is investigated.

  3. Development of Integrated Orbit and Attitude Software-in-the-loop Simulator for Satellite Formation Flying

    NASA Astrophysics Data System (ADS)

    Park, Han-Earl; Park, Sang-Young; Park, Chandeok; Kim, Sung-Woo

    2013-03-01

    An integrated orbit and attitude control algorithm for satellite formation flying was developed, and an integrated orbit and attitude software-in-the-loop (SIL) simulator was also developed to test and verify the integrated control algorithm. The integrated algorithm includes state-dependent Riccati equation (SDRE) control algorithm and PD feedback control algorithm as orbit and attitude controller respectively and configures the two algorithms with an integrating effect. The integrated SIL simulator largely comprises an orbit SIL simulator for orbit determination and control, and attitude SIL simulator for attitude determination and control. The two SIL simulators were designed considering the performance and characteristics of related hardware-in-the-loop (HIL) simulators and were combined into the integrated SIL simulator. To verify the developed integrated SIL simulator with the integrated control algorithm, an orbit simulation and integrated orbit and attitude simulation were performed for a formation reconfiguration scenario using the orbit SIL simulator and the integrated SIL simulator, respectively. Then, the two simulation results were compared and analyzed with each other. As a result, the user satellite in both simulations achieved successful formation reconfiguration, and the results of the integrated simulation were closer to those of actual satellite than the orbit simulation. The integrated orbit and attitude control algorithm verified in this study enables us to perform more realistic orbit control for satellite formation flying. In addition, the integrated orbit and attitude SIL simulator is able to provide the environment of easy test and verification not only for the existing diverse orbit or attitude control algorithms but also for integrated orbit and attitude control algorithms.

  4. Precise orbit determination of low-Earth satellites using SST data

    Microsoft Academic Search

    Z. Kang; P. Schwintzer; Ch. Reigber; S. Y Zhu

    1997-01-01

    The Satellite-to-Satellite Tracking (SST) in the high-low and\\/or low-low configuration is presently considered as being the most promising method for precise orbit determination and global gravity field recovery. Particularly, the use of the GPS system for orbit determination in the high-low configuration has been extensively studied and successfully tested on TOPEX\\/Poseidon. Recently, many space missions (e.g. CHAMP, STEP) have shown

  5. Domestic satellite communications overview

    NASA Astrophysics Data System (ADS)

    Nickelson, R. L.

    1984-09-01

    The current status and future planning of satellite systems for intranational communication are examined in a summary of presentations given at the CCIR international seminar on domestic satellite communications held in Shanghai in October 1983. Topics discussed include operational and planned systems in Australia, Japan, the U.S., India, China, France, Brazil, Italy, Thailand, and the European region; development and planning by NASA and Intelsat; systems for rural areas or light traffic; modulation and multiple access; antennas, propagation, and interference; geostationary orbits; and economics, planning, and implementation.

  6. High precision and convenient extension simulation platform for satellite attitude and orbit system

    NASA Astrophysics Data System (ADS)

    Cui, Hongzheng; Han, Chao; Chen, Pei; Luo, Qinqin

    2012-01-01

    In this paper, a high precision and convenient extension simulation platform for satellite attitude and orbit system is developed, to demonstrate the satellite attitude and orbit system for given space mission, and test the new underdeveloped algorithms for attitude/orbit dynamics, attitude determination, orbit navigation, and attitude/orbit control. The simulation platform is based on Matlab/Simulink software, using the technique of Simulink modeling, importing C/Fortran code in Matlab/Simulink, and embedded Matlab function, with beautiful reusability, inheritability and expansibility. The paper orderly presents the background behind the development of the platform, the platform design architecture and capability, the validity of the platform, the inheritability and expansibility of the platform, the platform implementation example for Chinese weather satellite (FY-3), and the future development for the platform.

  7. High precision and convenient extension simulation platform for satellite attitude and orbit system

    NASA Astrophysics Data System (ADS)

    Cui, Hongzheng; Han, Chao; Chen, Pei; Luo, Qinqin

    2011-12-01

    In this paper, a high precision and convenient extension simulation platform for satellite attitude and orbit system is developed, to demonstrate the satellite attitude and orbit system for given space mission, and test the new underdeveloped algorithms for attitude/orbit dynamics, attitude determination, orbit navigation, and attitude/orbit control. The simulation platform is based on Matlab/Simulink software, using the technique of Simulink modeling, importing C/Fortran code in Matlab/Simulink, and embedded Matlab function, with beautiful reusability, inheritability and expansibility. The paper orderly presents the background behind the development of the platform, the platform design architecture and capability, the validity of the platform, the inheritability and expansibility of the platform, the platform implementation example for Chinese weather satellite (FY-3), and the future development for the platform.

  8. Orbits of Potential Pluto Satellites and Rings Between Charon and Hydra

    E-print Network

    Porter, Simon B

    2015-01-01

    Pluto and its five known satellites form a complex dynamic system. Here we explore where additional satellites could exist exterior to Charon (the innermost moon) but interior of Hydra (the outermost). We also provide dynamical constraints for the masses of the known satellites. We show that there are significant stable regions interior of Styx and between Nix and Kerberos. In addition, we show that coorbitals of the known small satellites are stable, even at high inclinations, and discuss mass constraints on undiscovered satellites in such orbits.

  9. Attitude and orbit control of small satellites for autonomous terrestrial target tracking

    NASA Astrophysics Data System (ADS)

    Ibrahim, Najmus S.

    Terrestrial target tracking using low Earth orbit satellites provides essential daily services and vital scientific data. In this thesis, the Attitude and Orbit Control System of such a terrestrial tracking satellite, Nanosatellite for Earth Monitoring and Observation Aerosol Monitor, is presented in detail. The satellite is a new generation Earth observation mission with the objective of detecting global atmospheric aerosol content through sub-degree pointing. The design is presented from initial hardware selection and budget development to operation definition and mission operation. The efficacy of performing precise autonomous Earth-pointing on a small satellite platform is validated through high fidelity simulations involving satellite and environmental dynamics, test-characterized hardware models and flight software-in-the-loop. The results provide practical target tracking methodologies which in the past have been publicly inaccessible to the author's best knowledge and which can be now be applied to a broad range of precise Earth-pointing satellites.

  10. Accurate orbit determination strategies for the tracking and data relay satellites

    Microsoft Academic Search

    D. H. Oza; D. T. Bolvin; J. M. Lorah; T. Lee; C. E. Doll

    1995-01-01

    The National Aeronautics and Space Administration (NASA) has developed the Tracking and Data Relay Satellite (TDRS) System (TDRSS) for tracking and communications support of low Earth-orbiting satellites. TDRSS has the operational capability of providing 85% coverage for TDRSS-user spacecraft. TDRSS currently consists of five geosynchronous spacecraft and the White Sands Complex (WSC) at White Sands, New Mexico. The Bilateration Ranging

  11. GPS TERMINOLOGY Data transmitted by a GPS satellite which includes orbital information on all

    E-print Network

    Berns, Hans-Gerd

    A.1 APPENDIX GPS TERMINOLOGY Almanac Data transmitted by a GPS satellite which includes orbital information on all the satellites, clock correction, and atmospheric delay parameters. These data are used at a single receiver. Argument of Latitude The sum of the true anomaly and the argument of perigee. Argument

  12. On-Orbit Flight Results from the Reconfigurable Cibola Flight Experiment Satellite (CFESat)

    Microsoft Academic Search

    Michael P. Caffrey; Keith Morgan; Diane Roussel-Dupre; Scott Robinson; Anthony Nelson; Anthony Salazar; Michael J. Wirthlin; William Howes; Daniel Richins

    2009-01-01

    The Cibola Flight Experiment (CFE) is an exper- imental small satellite developed at the Los Alamos National Laboratory to demonstrate the feasibility of using FPGA-based reconfigurable computing for sensor processing in a space en- vironment. The CFE satellite was launched on March 8, 2007 in low-earth orbit and has operated extremely well since its deployment. The nine Xilinx Virtex FPGAs

  13. Field Tests of a Gas-Filter Imaging Radiometer for Methane, CH4,: A Prototype for Geostationary Remote Infrared Pollution Sounder, GRIPS

    NASA Astrophysics Data System (ADS)

    Dickerson, R. R.; Fish, C. S.; Brent, L. C.; Burrows, J. P.; Fuentes, J. D.; Gordley, L. L.; Jacob, D. J.; Schoeberl, M. R.; Salawitch, R. J.; Ren, X.; Thompson, A. M.

    2013-12-01

    Gas filter radiometry is a powerful tool for measuring infrared active trace gases. Methane (CH4) is the second most important greenhouse gas and is more potent molecule for molecule than carbon dioxide (CO2). Unconventional natural gas recovery has the potential to show great environmental benefits relative to coal, but only if fugitive leakage is held below 3% and leak rates remain highly uncertain. We present design specifications and initial field/aircraft test results for an imaging remote sensing device to measure column content of methane. The instrument is compared to in situ altitude profiles measured with cavity ring-down. This device is an airborne prototype for the Geostationary Remote Infrared Pollution Sounder, GRIPS, a satellite instrument designed to monitor CH4, CO2, CO, N2O and AOD from geostationary orbit, with capabilities for great advances in air quality and climate research. GRIPS: The Geostationary Remote Infrared Pollution Sounder

  14. A new global Earth's gravity field model from satellite orbit perturbations: GRIM5-S1

    Microsoft Academic Search

    Richard Biancale; Georges Balmino; Jean-Michel Lemoine; Jean-Charles Marty; Bernard Moynot; Francois Barlier; Pierre Exertier; Olivier Laurain; Pascal Gegout; Peter Schwintzer; Christoph Reigber; Albert Bode; Rolf König; Franz-Heinrich Massmann; Jean-Claude Raimondo; Roland Schmidt; Sheng Yuan Zhu

    2000-01-01

    A new model of the Earth's gravity field, called GRIM5-S1, was prepared in a joint German-French effort. The solution is based on satellite orbit perturbation analysis and exploits tracking data from 21 satellites to solve simultaneously for the gravitational and ocean tide potential and tracking station positions. The satellite-only solution results in a homogeneous representation of the geoid with an

  15. OLFAR a radio telescope based on nano satellites in moon orbit

    Microsoft Academic Search

    S. Engelen; C. J. M. Verhoeven; M. J. Bentum

    2010-01-01

    It seems very likely that missions with nano-satellites in professional scientific or commercial applications will not be single-satellite missions. Well structured formations or less structured swarms of nano-satellites will be able to perform tasks that cannot be done in the “traditional” way. The Dutch space-born radio telescope project OLFAR, the Orbiting Low Frequency Array, is a good example of a

  16. Geostationary Operational Environmental Statellite(GEOS-N report)

    NASA Astrophysics Data System (ADS)

    1991-12-01

    The Advanced Missions Analysis Office (AMAO) of GSFC has completed a study of the Geostationary Operational Environmental Satellites (GOES-N) series. The feasibility, risks, schedules, and associated costs of advanced space and ground system concepts responsive to National Oceanic and Atmospheric Administration (NOAA) requirements were evaluated. The study is the first step in a multi-phased procurement effort that is expected to result in launch ready hardware in the post 2000 time frame. This represents the latest activity of GSFC in translating meteorological requirements of NOAA into viable space systems in geosynchronous earth orbits (GEO). GOES-N represents application of the latest spacecraft, sensor, and instrument technologies to enhance NOAA meteorological capabilities via remote and in-situ sensing from GEO. The GOES-N series, if successfully developed, could become another significant step in NOAA weather forecasting space systems, meeting increasingly complex emerging national needs for that agency's services.

  17. Geostationary Operational Environmental Statellite(GEOS-N report)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Advanced Missions Analysis Office (AMAO) of GSFC has completed a study of the Geostationary Operational Environmental Satellites (GOES-N) series. The feasibility, risks, schedules, and associated costs of advanced space and ground system concepts responsive to National Oceanic and Atmospheric Administration (NOAA) requirements were evaluated. The study is the first step in a multi-phased procurement effort that is expected to result in launch ready hardware in the post 2000 time frame. This represents the latest activity of GSFC in translating meteorological requirements of NOAA into viable space systems in geosynchronous earth orbits (GEO). GOES-N represents application of the latest spacecraft, sensor, and instrument technologies to enhance NOAA meteorological capabilities via remote and in-situ sensing from GEO. The GOES-N series, if successfully developed, could become another significant step in NOAA weather forecasting space systems, meeting increasingly complex emerging national needs for that agency's services.

  18. Error assessment of an autonomous real-time precision orbit determination program for a low-earth-orbit satellite using GPS observation data

    Microsoft Academic Search

    Jung Hyun Jo

    2002-01-01

    An autonomous, real-time, precision orbit determination (ARTPOD) program for low-Earth-orbit (LEO) satellites using the Global Positioning System (GPS) is planned and developed. Numerical simulations are used to assess the anticipated accuracy of LEO satellite tracking using GPS observation data. The GPS observation data for a particular LEO satellite, CHAMP (Challenging Mini-satellite Payload), is processed with the ARTPOD program and results

  19. ORBIT DETERMINATION USING GPS CONSIDERING DIRECT SOLAR RADIATION PRESSURE MODEL FOR THE TOPEX\\/POSEIDON SATELLITE

    Microsoft Academic Search

    Paula Cristiane Pinto Raimundo; Helio Koiti Kuga; Rodolpho Vilhena De Moraes

    Abstract.The main target here is to determine the orbit of an artificial satellite, using signals of the GPS constellation and least squares algorithms through sequential Givens rotations as the method of estimation, with the aim of improving the performance of the orbit estimation process and, at the same time, minimizing the computational procedure cost. Perturbations up to ,high order geopotential

  20. Hybrid precision orbit determination for low altitude satellites by GPS tracking

    Microsoft Academic Search

    Seung-Woo Lee

    2002-01-01

    A numerical simulation study was performed in order to investigate the effects of process noise modeling on state estimates of a Low Earth Orbiting (LEO) satellite in the GPS-based hybrid Precise Orbit Determination (POD) strategy. The use of simulated data enabled the creation of the simulated data with three different correlation types of the unknown forces, which were constant in

  1. Long-term collision risk prediction for low earth orbit satellite constellations

    Microsoft Academic Search

    G. G. Swinerd; P. H. Stokes; J. E. Wilkinson

    2000-01-01

    In the light of recent changes to planned Low Earth Orbit (LEO) satellite constellation designs and enhancements made to the DERA IDES model, we have conducted a new study on long-term debris environment evolution. This includes the collision interactions of constellation systems with the orbital debris environment over the next 50 years. In this new study, we use the IDES

  2. Satellite Orbit Determination Using a Single-Channel Global Positioning System Receiver

    Microsoft Academic Search

    Mark L. Psiaki

    2002-01-01

    A proposed satellite orbit determination system has been analyzed, one that uses measurements from a single-channel Global Positioning System (GPS) receiver. The purpose of this study is to predict the likely efficacy of a low-power autonomous orbit determination system. The system processes the pseudo range outputs of the receiver using an extended Kalman filter. The receiver cycles through different GPS

  3. Lunar satellite orbit determination analysis and quality assessment from Lunar Prospector tracking data and SELENE simulations

    Microsoft Academic Search

    Sander Goossens; Koji Matsumoto

    2007-01-01

    Low lunar satellite orbit accuracy is assessed by means of the analysis of tracking data residuals, orbit overlap statistics and covariance propagation. A full-scale determination of a degree and order 75 spherical harmonics lunar gravity field model from 3 months of Lunar Prospector tracking data shows the influence of processing strategies for gravity field modelling. Despite large differences in gravity

  4. Effect of Ellipticity of the Equator on 24Hour Nearly Circular Satellite Orbits

    Microsoft Academic Search

    Leon Blitzer; E. M. Boughton; G. Kang; R. M. Page

    1962-01-01

    The influence of the principal longitude-dependent term of the earth's potential on the orbit of a 24-hour satellite is investigated. It is found that in a coordinate frame rotating with the earth there are four possible stationary points for circular orbits, symmetrically situ- ated on the extensions of the principal axes of the equatorial ellipse. The two points on the

  5. Simultaneous laser ranging and communication from an Earth-based satellite laser ranging station to the Lunar Reconnaissance Orbiter in lunar orbit

    E-print Network

    Sun, Xiaoli

    We report a free space laser communication experiment from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit through the on board ...

  6. THE ORBITS OF THE NEPTUNIAN SATELLITES AND THE ORIENTATION OF THE POLE OF NEPTUNE

    SciTech Connect

    Jacobson, R. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)], E-mail: robert.jacobson@jpl.nasa.gov

    2009-05-15

    This paper reports on an update to the orientation of Neptune's pole and to the orbits of the Neptunian satellites, Triton, Nereid, and Proteus. We determined the new pole and orbits in the International Celestial Reference Frame by fitting them to all available observations through the opposition of 2008. The new data in the fit are high-quality modern astrometry and constitute a 19 year extension of the previous data arc. We assess the accuracy of the orbits and compare them with our earlier orbits. We also provide mean elements as a geometrical description for the orbits.

  7. GeoSTAR: a geostationary microwave sounder for the future

    NASA Astrophysics Data System (ADS)

    Lambrigtsen, B. H.; Brown, S. T.; Dinardo, S. J.; Gaier, T. C.; Kangaslahti, P. P.; Tanner, A. B.

    2007-09-01

    The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new Earth remote sensing instrument concept that has been under development at the Jet Propulsion Laboratory. First conceived in 1998 as a NASA New Millennium Program mission and subsequently developed in 2003-2006 as a proof-of-concept prototype under the NASA Instrument Incubator Program, it is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. The importance of such observations have been recognized by the National Academy of Sciences National Research Council, which recently released its report on a "Decadal Survey" of NASA Earth Science activities. One of the recommended missions for the next decade is a geostationary microwave sounder. GeoSTAR is well positioned to meet the requirements of such a mission, and because of the substantial investment NASA has already made in GeoSTAR technology development, this concept is fast approaching the necessary maturity for implementation in the next decade. NOAA is also keenly interested in GeoSTAR as a potential payload on its next series of geostationary weather satellites, the GOES-R series. GeoSTAR, with its ability to map out the three-dimensional structure of temperature, water vapor, clouds, precipitation and convective parameters on a continual basis, will significantly enhance our ability to observe hurricanes and other severe storms. In addition, with performance matching that of current and next generation of low-earth-orbiting microwave sounders, GeoSTAR will also provide observations important to the study of the hydrologic cycle, atmospheric processes and climate variability and trends. In particular, with GeoSTAR it will be possible to fully resolve the diurnal cycle. We discuss the GeoSTAR concept and basic design, the performance of the prototype, and a number of science applications that will be possible with GeoSTAR. The work reported on here was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.

  8. Geo-STAR: A Geostationary Microwave Sounder for the Future

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn H.; Brown, S. T.; Dinardo, S. J.; Gaier, T. C.; Kangaslahti, P. P.; Tanner, A. B.

    2007-01-01

    The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new Earth remote sensing instrument concept that has been under development at the Jet Propulsion Laboratory. First conceived in 1998 as a NASA New Millennium Program mission and subsequently developed in 2003-2006 as a proof-of-concept prototype under the NASA Instrument Incubator Program, it is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. The importance of such observations have been recognized by the National Academy of Sciences National Research Council, which recently released its report on a 'Decadal Survey' of NASA Earth Science activities1. One of the recommended missions for the next decade is a geostationary microwave sounder. GeoSTAR is well positioned to meet the requirements of such a mission, and because of the substantial investment NASA has already made in GeoSTAR technology development, this concept is fast approaching the necessary maturity for implementation in the next decade. NOAA is also keenly interested in GeoSTAR as a potential payload on its next series of geostationary weather satellites, the GOES-R series. GeoSTAR, with its ability to map out the three-dimensional structure of temperature, water vapor, clouds, precipitation and convective parameters on a continual basis, will significantly enhance our ability to observe hurricanes and other severe storms. In addition, with performance matching that of current and next generation of low-earth-orbiting microwave sounders, GeoSTAR will also provide observations important to the study of the hydrologic cycle, atmospheric processes and climate variability and trends. In particular, with GeoSTAR it will be possible to fully resolve the diurnal cycle. We discuss the GeoSTAR concept and basic design, the performance of the prototype, and a number of science applications that will be possible with GeoSTAR. The work reported on here was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.

  9. Beam-waveguide antenna servo design issues for tracking low earth-orbiting satellites

    NASA Technical Reports Server (NTRS)

    Gawronski, W. K.; Mellstrom, J. A.

    1993-01-01

    Upcoming NASA missions will require tracking of low-orbit satellites. As a consequence, NASA antennas will be required to track satellites at higher rates than for the current deep space missions. This article investigates servo design issues for the 34-m beam-waveguide antennas that track low-orbit satellites. This includes upgrading the servo with a feedforward loop, using a monopulse controller design, and reducing tracking errors through either proper choice of elevation pinion location, application of a notch filter, or adjustment of the elevation drive amplifier gain. Finally, improvement of the signal-to-noise ratio through averaging of the over-sampled monopulse signal is described.

  10. Rapid orbit determination of LEO satellites using IGS clock and ephemeris products

    Microsoft Academic Search

    Oliver Montenbruck; Eberhard Gill; Remco Kroes

    2005-01-01

    Different types of GPS clock and orbit data provided by the International GPS Service (IGS) have been used to assess the accuracy\\u000a of rapid orbit determination for satellites in low Earth orbit (LEO) using spaceborne GPS measurements. To avoid the need\\u000a for reference measurements from ground-based reference receivers, the analysis is based on an undifferenced processing of\\u000a GPS code and

  11. Impact of GPS satellite antenna offsets on GPS-based precise orbit determination

    Microsoft Academic Search

    Z. Kang; B. Tapley; J. Ries; S. Bettadpur; P. Nagel

    2007-01-01

    Since the successful demonstration of GPS-based Precise Orbit Determination (POD) on TOPEX\\/Poseidon in 1992, GPS-based POD for Low-Earth Orbiters (LEO) such as the CHAMP and GRACE satellites has become a popular method. The orbit accuracy of GPS-based POD has been improved from 3cm to 1cm in the radial direction. In order to achieve higher-accuracy results, it is necessary to understand

  12. Statistical analysis of Pi2 pulsation by polar orbiting DE1 satellite and three mid- and low- latitude ground stations

    Microsoft Academic Search

    M. Teramoto; M. Nose

    2006-01-01

    Some previous studies have shown that the mid- and low- latitude Pi2 pulsations can be explained by a resonance mechanism in the inner magnetosphere (cavity mode), analyzing magnetic field data from ground stations and satellites. In these studies, satellites orbiting near the equatorial plane were used; there is no statistical study of Pi2 by polar orbiting satellites. We have been

  13. Satellite perturbations and orbital determination; Proceedings of the Topical Meeting, Budapest, Hungary, June 2-14, 1980

    Microsoft Academic Search

    P. Lala

    1981-01-01

    Papers are presented on the use of point mass models of the geopotential for orbit predictions, on earth ocean tides from long-term analysis of satellite orbits, on the motion of an artificial satellite under the terrestrial radiation pressure, and on the generation of satellite position (and velocity) by a mixed analytical-numerical procedure. Attention is also given to the possibilities of

  14. Experimental Program and Performance of Japan's Communication Satellite (CS) and Its First Results

    Microsoft Academic Search

    KEN-ICHI TSUKAMOTO; YUICHI OTSU; KATSUHIKO KOSAKA; TADASHI SHIOMI; HIDEICHI SASAOKA

    1979-01-01

    Japan's CS spacecraft was launched successfully in December 1977 and placed at 135°E longitude in a geostationary orbit. On-orbit performance of the satellite was verified quite well with the exception of two sets ofK-band transponders. Substantial communication experiments have been conducted for more than half a year starting in May, 1978. In the satellite loop-back configuration at the Main Fixed

  15. Programmes and long term strategies of the European Organisation for Meteorological Satellites

    NASA Astrophysics Data System (ADS)

    Morgan, John

    1992-08-01

    The policies and objectives of Eumetsat are presented, leading to an agreed approach for the procurement of future Eumetsat satellite systems. These policies are related to the plans and requirements for future systems that will become the core Eumetsat activities in the next century's early decades. Plans include the development of a replacement for the successful Meteosat satellite series in geostationary orbit and a new capability to provide essential global data from polar orbit.

  16. A method of autonomous orbit determination for satellite using star sensor

    NASA Astrophysics Data System (ADS)

    Ma, Jianbo; Xu, Jin; Cao, Zhibin

    2005-05-01

    In this paper a method of autonomous orbit determination using star sensor is studied. By building relatively consummate dynamical models which simulate attitude motion of satellite and observation from satellite to background stars, the simulant computation of this method is executed, and it is shown that the method of autonomous orbit determination is feasible. Academic and calculation analyses have been done for the relation between the direction of star sensor with respect to statellite-body coordinate system and the accuracy of autonomous orbit determination.

  17. Contribution of Inter-Satellite Range Measurements to the Inner Precision of GNSS Orbits

    NASA Astrophysics Data System (ADS)

    Stetter, Monika; Hugentobler, Urs; Schlicht, Anja

    2015-04-01

    Today's precise orbit determination is exclusively based on observations taken from ground, for instance GNSS- or SLR- observations. Measuring GNSS satellites from the surface of the Earth results in a poor observation geometry. In addition, ground-based observations are affected by tropospheric delay errors. GNSS Inter-satellite range measurements, on the other hand, provide a much better observation geometry for precise orbit determination. In addition they are not affected by tropospheric errors. A network of inter-satellite measurements can be used to tightly interlink the orbits in the GNSS constellation. The resulting satellite orbits can be considered a realization of a dynamic reference system. This reference frame can be connected with the ITRF introducing additional observations from GNSS ground stations. Alternatively, the link to a quasi-inertial reference frame is given through perturbing forces only, such as radiation pressure and gravitational force of moon and sun, acting on the satellite. The resulting orientation stability of the satellite orbit constellation is assessed in the absence of ground-based observations and as a function of the number of ground-based observing stations.

  18. Icy Satellites Impactor Probes for the Jovian Icy Moons Orbiter

    NASA Technical Reports Server (NTRS)

    Shirley, J. H.; Zimmerman, W. F.; Strauss, W.; Ivlev, R.; Duong, T.; Hunter, D.; Slimko, E.; Nacaise, F.; Archer, E.; Nesmith, B.

    2003-01-01

    We present a preliminary design and mission description for Icy Satellites Impactor Probes (IPS). This design addresses two of the scientific themes of this Icy Galilean Satellites Forum: Surface Chemistry and Geophysics, and Interior Structures. Impactor probes may also make significant contributions in the areas of surface geology and mineralogy.

  19. Geomagnetic shielding of cosmic rays for different satellite orbits

    Microsoft Academic Search

    W. Heinrich; A. Spill

    1979-01-01

    In the present paper, a straightforward approximation is used to estimate cutoff probabilities for particles impinging vertically on the satellite, i.e., in the direction of the radius vector toward the center of the earth. It is seen that the best way to calculate exact cutoff probabilities for a satellite is to use the trajectory tracing technique. However, since this technique

  20. Precision in the orbit determination of the TOPEX\\/POSEIDON satellite using GPS and recursive least squares method

    Microsoft Academic Search

    R. Vilhena de Moraes; H. Kuga; A. Silva

    2002-01-01

    The Global Positioning System is a powerful and low cost process to compute orbits for some artificial Earth satellites. The aim of this work is to consider a low computer cost procedure to determine the orbit of an artificial satellite using data from an onboard GPS receiver. Pseudoranges are used in the measurement equations for the orbit estimator. The least

  1. Network Performance of Non-Geostationary Constellations Equipped With Intersatellite Links

    Microsoft Academic Search

    Lloyd Wood

    1995-01-01

    An ideal, simplified, non-geostationary satellite constellation network, with varying numbers of intersatellite links on each satellite, is presented and analysed, using a minimum-path, circuit-switching approach.

  2. Current status and future prospect of Akebono satellite in orbit over 20 years

    NASA Astrophysics Data System (ADS)

    Miyake, Wataru; Matsuoka, Ayako

    Akebono satellite was launched in 1989 into the polar orbit for studying the auroral plasma physics. The mission was successfully carried out and lots of scientific results have been pub-lished. Whereas some instrumental degradation and failure have been accumulated over 20 years, the satellite is still in operation. The satellite conditions and interests of scientific com-munity have changed its main objectives from the auroral physics towards research on the inner magnetosphere. This paper presents the current status and future prospect of the satel-lite conditions to accomplish the extended mission for studying the radiation belt and the plasmasphere.

  3. Errors in Long Term Orbital Prediction for Satellite 196101

    Microsoft Academic Search

    Robert R. Newton

    1964-01-01

    The results of orbital prediction over periods of 2 to 6 months are presented. The orbits used in the predictions were based on Doppler data obtained within not more than 24 hours. After removal of the drag contribution, the remaining prediction error is found to grow linearly with time, contrary to the theory of Moe. An alternative expression for the

  4. Fragmentation of asteroids and artificial satellites in orbit

    Microsoft Academic Search

    W. Wiesel

    1978-01-01

    This paper develops expressions for the probability density in the orbital elements resulting from a spherical explosion in orbit. The usual power-law mass distribution is employed, and it is assumed that equipartition holds among velocity dispersions and masses. The asteroid families Themis, Eos, and Coronis (at least) show an envelope in the semimajor axis-diameter plane which is completely characteristic of

  5. A mathematical simulation of earth satellite explosion debris orbital elements 

    E-print Network

    Mabrey, Wayne Edward

    1970-01-01

    of the cart'h Magnitude of drag i'orce V CD Speed of satellite relative to the local atmosphere Drag coefficient *Except for related symbols being grouped together, the order is generally that in which the symbols appear. Area of satellite, also used... particular satellite and write x=-~x/r +X y=-~y/r +Y z = -~ z/r + where (X, Y, Z) are the components of the perturbation accelerations. This system of coupled second order ordinary differential equations involves six constants of integration which...

  6. IMS/Satellite Situation Center report. Predicted orbit plots for IMP-H-1976. [Explorer 47 satellite

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Predicted orbit plots are shown in three projections. The time period covered by each set of projections is 12 days 6 hours, corresponding approximately to the period of IMP-H satellite. The three coordinate systems used are the Geocentric Solar Ecliptic system (GSE), the Geocentric Solar Magnetospheric system (GSM), and the Solar Magnetic system (SM). For each of the three projections, time ticks and codes are given on the satellite trajectories. The codes are interpreted in the table at the base of each plot. Time is given in the table as year/day/decimal hour. The total time covered by each plot is shown at the bottom of each table. An additional variable is given in the table for each time tick. For the GSM and SM projection this variable is the geocentric distance to the satellite in earth radii, and for the GSE projection the variable is satellite ecliptic latitude in degrees.

  7. Comparison of the reduced dynamical orbit parametrization and precise non-conservative orbit force modeling for DORIS satellites

    NASA Astrophysics Data System (ADS)

    Stepanek, P.; Rodriguez-Solano, C.; Filler, V.; Hugentobler, U.

    2011-12-01

    The focus of the studies is the analysis of the comparison between two different approaches for LEO satellite orbit estimation employing DORIS measurements. The first one is the reduced-dynamical model, based on the orbit modeling by using the empirical and the pseudo-stochastic parameters. The second approach includes the attitude models and the CNES-developed satellite macromodels, with modeling of non-conservative acceleration, i.e., Sun radiation pressure, Earth radiation pressure and atmospheric drag. Both approaches are used at analysis centers providing DORIS solutions. The reduced-dynamical modeling is currently used by the GOP analysis center, which achieves similar accuracy of the free-network solutions as the other centers utilizing a precise non-conservative force modeling. The GOP works with a modified version of the Bernese GPS Software that has not included the non-conservative modeling. This limitation is now overcome by the new scientific modification of the software, which opens the unique possibility to compare both approaches by using the same software platform. We compare external and internal precision of the estimated orbits. We also analyze the individual satellite free-network DORIS solutions and time-series of derived parameters, i.e., station coordinates, TRF scale, the geocenter variations and the Earth rotation parameters. The studies highlight the main differences in the results that should answer the question whether the modeling of non-conservative forces including the CNES box-wing satellite models actually brings a significant improvement to the DORIS solutions.

  8. Separation requirements for protection of high altitude satellites from co-orbital antisatellite weapons

    SciTech Connect

    Wojcik, L.A.

    1985-01-01

    This thesis estimates lower bounds to initial separation distances required for safety of maneuverable, shielded satellites against destruction by pre-deployed, co-orbital, nuclear-armed antisatellite (ASAT) weapons with maneuvering capability. Offensive and defensive designs are constrained by reasonable bounds on cost and mass. For satellites in circular Earth orbit with a radius to twice the geosynchronous radius, the lower bound for thirty minutes of safety after initiation of an attack is found to be on the order of thousands of kilometers. The lower bound is not substantially greater for x-ray lasers than for simple nuclear warheads, except perhaps for very long x-ray lasers. The danger to strategic satellites does not depend on the development of exotic energy-beam weapons, but would arise if reliable command and control (CS) and guidance capabilities for maneuverable ASATs in high orbit were successfully developed. Current ASAT programs in the United States and Soviet Union have included development and testing of limited CS and guidance capabilities. Although neither side is known to presently have an ASAT system capable of attacking high-altitude satellites, the danger to satellites in high orbit from capabilities being currently developed suggests that the danger be addressed in the near future. One approach is to attempt to negotiate an agreement with the Soviet Union on separation rules for objects in high orbit. Separation rules offer the potential for a means of mitigating crisis and arms race instabilities introduced by ASAT weapons.

  9. Orbital Injection of the SEDSAT Satellite: Tethered Systems Dynamics and Flight Data Analysis

    NASA Technical Reports Server (NTRS)

    Lorenzini, Enrico C.; Gullahorn, Gordon E.; Cosmo, Mario L.; Ruiz, Manuel; Pelaez, Jesus

    1996-01-01

    This report deals with the following topics which are all related to the orbital injection of the SEDSAT satellite: Dynamics and Stability of Tether Oscillations after the First Cut. The dynamics of the tether after the first cut (i.e., without the Shuttle attached to it) is investigated. The tether oscillations with the free end are analyzed in order to assess the stability of the rectilinear configuration in between the two tether cuts; analysis of Unstable Modes. The unstable modes that appear for high libration angles are further investigated in order to determine their occurrences and the possible transition from bound librations to rotations; Orbital Release Strategies for SEDSAT. A parametric analysis of the orbital decay rate of the SEDSAT satellite after the two tether cuts has been carried out as a function of the following free parameters: libration amplitude at the end of deployment, deviation angle from LV at the first cut, and orbital anomaly at the second cut. The values of these parameters that provide a minimum orbital decay rate of the satellite (after the two cuts) have been computed; and Dynamics and Control of SEDSAT. The deployment control law has been modified to cope with the new ejection velocity of the satellite from the Shuttle cargo bay. New reference profiles have been derived as well as new control parameters. Timing errors at the satellite release as a function of the variations of the initial conditions and the tension model parameters have been estimated for the modified control law.

  10. Impact of GPS satellite antenna offsets on GPS-based precise orbit determination

    NASA Astrophysics Data System (ADS)

    Kang, Z.; Tapley, B.; Ries, J.; Bettadpur, S.; Nagel, P.

    Since the successful demonstration of GPS-based Precise Orbit Determination (POD) on TOPEX/Poseidon in 1992, GPS-based POD for Low-Earth Orbiters (LEO) such as the CHAMP and GRACE satellites has become a popular method. The orbit accuracy of GPS-based POD has been improved from 3 cm to 1 cm in the radial direction. In order to achieve higher-accuracy results, it is necessary to understand and try to reduce the impact of various error sources on the orbits. One of them is the GPS satellite antenna offset. Currently, most GPS data processing institutions are using relative GPS satellite antenna offsets, and there are big differences (meter level) between the antenna offsets. In addition, accurate antenna offset values can be only estimated from processing GPS data currently with an accuracy of cm to dm levels. In this paper, we studied the impact of GPS satellite antenna offsets on GPS-based POD using the different offsets. The results show that the antenna offsets have large effects (a few cm) on the GPS onboard receiver antenna estimation and relatively small effects (about one cm) on the satellite orbit accuracy.

  11. Measurement of Satellite Impact Test Fragments for Modeling Orbital Debris

    NASA Technical Reports Server (NTRS)

    Hill, Nicole M.

    2009-01-01

    There are over 13,000 pieces of catalogued objects 10cm and larger in orbit around Earth [ODQN, January 2009, p12]. More than 6000 of these objects are fragments from explosions and collisions. As the earth-orbiting object count increases, debris-generating collisions in the future become a statistical inevitability. To aid in understanding this collision risk, the NASA Orbital Debris Program Office has developed computer models that calculate quantity and orbits of debris both currently in orbit and in future epochs. In order to create a reasonable computer model of the orbital debris environment, it is important to understand the mechanics of creation of debris as a result of a collision. The measurement of the physical characteristics of debris resulting from ground-based, hypervelocity impact testing aids in understanding the sizes and shapes of debris produced from potential impacts in orbit. To advance the accuracy of fragment shape/size determination, the NASA Orbital Debris Program Office recently implemented a computerized measurement system. The goal of this system is to improve knowledge and understanding of the relation between commonly used dimensions and overall shape. The technique developed involves scanning a single fragment with a hand-held laser device, measuring its size properties using a sophisticated software tool, and creating a three-dimensional computer model to demonstrate how the object might appear in orbit. This information is used to aid optical techniques in shape determination. This more automated and repeatable method provides higher accuracy in the size and shape determination of debris.

  12. Satellite-Based Precipitation Measurement Using PERSIANN System

    Microsoft Academic Search

    Kuo-Lin Hsu; Soroosh Sorooshian

    PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks) is a satellite-based\\u000a rainfall estimation algorithm. It uses local cloud textures from longwave infrared images of the geostationary environmental\\u000a satellites to estimate surface rainfall rates based on an artificial neural network algorithm. Model parameters are frequently\\u000a updated from rainfall estimates provided by low-orbital passive microwave rainfall estimates. The PERSIANN

  13. Survey: National Environmental Satellite Service

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The national Environmental Satellite Service (NESS) receives data at periodic intervals from satellites of the Synchronous Meteorological Satellite/Geostationary Operational Environmental Satellite series and from the Improved TIROS (Television Infrared Observational Satellite) Operational Satellite. Within the conterminous United States, direct readout and processed products are distributed to users over facsimile networks from a central processing and data distribution facility. In addition, the NESS Satellite Field Stations analyze, interpret, and distribute processed geostationary satellite products to regional weather service activities.

  14. Satellite Formation Design in Orbits of High Eccentricity for Missions with Performance Criteria Specified over a Region of Interest 

    E-print Network

    Roscoe, Christopher

    2012-10-15

    Several methods are presented for the design of satellite formations for science missions in high-eccentricity reference orbits with quantifiable performance criteria specified throughout only a portion the orbit, called the Region of Interest (Ro...

  15. Instantaneous sampling accuracy of the Geostationary Earth Radiation Budget (GERB) experiment

    NASA Astrophysics Data System (ADS)

    Matthews, Grant

    2004-10-01

    Resolving uncertainties surrounding the nature of future climate change is currently one of the greatest challenges facing mankind. Validating climate model predictions of the currently much miss-represented cloud radiative feedback requires measurements made from orbit of the Earth Radiation Budget (ERB), specifically targeted at clouds. The ERB parameters for measure are the scattered solar or short wave (SW, 0.3-5?m) and the emitted thermal or long wave radiance (LW, 5-100?m). The Clouds and the Earth's Radiant Energy System (CERES), as part of NASA's Earth observing System, uses thermistor bolometer detectors to provide global high spatial resolution ERB measurements from polar orbiting space platforms. The Geostationary Earth Radiation Budget (GERB) experiment is a European Space Agency (ESA) project on board the spin stabilized Meteosat second Generation (MSG) platform. Location in geostationary orbit and the use of an array of thermopile detectors enables sampling of ERB radiances from the entire Earth disc at an optimum 5 minute temporal resolution. Taking full advantage of both GERB's time resolution and CERES's global coverage for climate science requires a radiometric cross calibration and validation between the two satellite programs. This study quantifies the instantaneous sampling errors incurred by the GERB instrument due to geo-location uncertainties and orbit spin axis miss-alignment. The results can therefore be characterized as a function of scene contrast, allowing an appropriate statistical weighting to be employed when making a radiometric comparison between the GERB and CERES instruments.

  16. A space weather forecasting system with multiple satellites based on a self-recognizing network.

    PubMed

    Tokumitsu, Masahiro; Ishida, Yoshiteru

    2014-01-01

    This paper proposes a space weather forecasting system at geostationary orbit for high-energy electron ?ux (>2 MeV). The forecasting model involves multiple sensors on multiple satellites. The sensors interconnect and evaluate each other to predict future conditions at geostationary orbit. The proposed forecasting model is constructed using a dynamic relational network for sensor diagnosis and event monitoring. The sensors of the proposed model are located at different positions in space. The satellites for solar monitoring equip with monitoring devices for the interplanetary magnetic ?eld and solar wind speed. The satellites orbit near the Earth monitoring high-energy electron ?ux. We investigate forecasting for typical two examples by comparing the performance of two models with different numbers of sensors. We demonstrate the prediction by the proposed model against coronal mass ejections and a coronal hole. This paper aims to investigate a possibility of space weather forecasting based on the satellite network with in-situ sensing. PMID:24803190

  17. Numerical determination of three-dimensional periodic orbits generated from vertical self-resonant satellite orbits

    Microsoft Academic Search

    I. A. Robin; V. V. Markellos

    1980-01-01

    The mechanism by which ‘vertical’ branches consisting of symmetric, three-dimensional periodic orbits bifurcate from families of plane orbits at ‘veertical self-resonant’ orbits is discussed, with emphasis on the relationship between symmetry properties and multiplicity, and methods for the numerical determination of such branches are described. As examples, eight new families of all symmetry classes which branch vertically from the familyf

  18. Optimum satellite orbits for accurate measurement of the earth's radiation budget, summary

    NASA Technical Reports Server (NTRS)

    Campbell, G. G.; Vonderhaar, T. H.

    1978-01-01

    The optimum set of orbit inclinations for the measurement of the earth radiation budget from spacially integrating sensor systems was estimated for two and three satellite systems. The best set of the two were satellites at orbit inclinations of 80 deg and 50 deg; of three the inclinations were 80 deg, 60 deg and 50 deg. These were chosen on the basis of a simulation of flat plate and spherical detectors flying over a daily varying earth radiation field as measured by the Nimbus 3 medium resolution scanners. A diurnal oscillation was also included in the emitted flux and albedo to give a source field as realistic as possible. Twenty three satellites with different inclinations and equator crossings were simulated, allowing the results of thousand of multisatellite sets to be intercompared. All were circular orbits of radius 7178 kilometers.

  19. Attractive manifold-based adaptive solar attitude control of satellites in elliptic orbits

    NASA Astrophysics Data System (ADS)

    Lee, Keum W.; Singh, Sahjendra N.

    2011-01-01

    The paper presents a novel noncertainty-equivalent adaptive (NCEA) control system for the pitch attitude control of satellites in elliptic orbits using solar radiation pressure (SRP). The satellite is equipped with two identical solar flaps to produce control moments. The adaptive law is based on the attractive manifold design using filtered signals for synthesis, which is a modification of the immersion and invariance (I&I) method. The control system has a modular controller-estimator structure and has separate tunable gains. A special feature of this NCEA law is that the trajectories of the satellite converge to a manifold in an extended state space, and the adaptive law recovers the performance of a deterministic controller. This recovery of performance cannot be obtained with certainty-equivalent adaptive (CEA) laws. Simulation results are presented which show that the NCEA law accomplishes precise attitude control of the satellite in an elliptic orbit, despite large parameter uncertainties.

  20. Interim Definitive Orbit for the Satellite 1959 Alpha Vanguard-II

    NASA Technical Reports Server (NTRS)

    1960-01-01

    A summary of certain position information indicating accuracies for the orbital arcs underlying the ephemeris is presented in table 1. The detailed ephemeris information is presented at the end of this report in the form of tables which give the latitude and longitude of the sub satellite point and the satellite height for each minute of time. The subsatellite point is defined here as the point on the earth's surface over which the satellite was determined to be at the indicated time. This form of presentation was recommended by the International Geophysical Year agencies concerned, for use in specifying the orbital positions of IGY satellites. Time is specified by giving in columns, the day, hour, and minute of Greenwich mean time.

  1. The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets.

    PubMed

    Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M

    2009-04-01

    We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary. PMID:19400731

  2. Lessons learned from hosting an Infrared Payload on a communications satellite

    Microsoft Academic Search

    J. Simonds; J. Z. Jacquot; C. Kersten; P. Lew; G. Sullivan

    2010-01-01

    This paper highlights salient lessons learned from the United States Air Force's (USAF) Commercially Hosted Infrared Program (CHIRP) and discusses how they may apply to future hosted infrared (IR) payloads on geostationary orbit communication satellites (comsat). The primary goal of the CHIRP program is to perform a technological demonstration to advance the Technological Readiness Level (TRL) of staring Wide Field

  3. Optimization of microwave power transmission from solar power satellites. Ph.D. Thesis

    Microsoft Academic Search

    1993-01-01

    Solar energy can be used to avoid environmental problems associated with the use of fossil fuels. Because of limitations on the availability of solar energy at the Earth`s surface, it is recommended that energy from the sun be harnessed by solar collectors in geostationary orbit, known as solar power satellites (SPS). The energy collected is transmitted to the Earth by

  4. Intercomparison of near-real-time biomass burning emissions estimates constrained by satellite fire data

    Microsoft Academic Search

    Jassim Al-Saadi; Amber J. Soja; R. Bradley Pierce; James Szykman; Christine Wiedinmyer; Louisa Emmons; Shobha Kondragunta; Xiaoyang Zhang; Chieko Kittaka; Todd Schaack; Kevin Bowmani

    2008-01-01

    We compare biomass burning emissions estimates from four different techniques that use satellite based fire products to determine area burned over regional to global domains. Three of the techniques use active fire detections from polar-orbiting MODIS sensors and one uses detections and instantaneous fire size estimates from geostationary GOES sensors. Each technique uses a different approach for estimating trace gas

  5. Convective cloud identification and classification in daytime satellite imagery using standard deviation limited adaptive clustering

    Microsoft Academic Search

    Todd A. Berendes; John R. Mecikalski; Wayne M. MacKenzie Jr.; Kristopher M. Bedka

    2008-01-01

    This paper describes a statistical clustering approach toward the classification of cloud types within meteorological satellite imagery, specifically, visible and infrared data. The method is based on the Standard Deviation Limited Adaptive Clustering (SDLAC) procedure, which has been used to classify a variety of features within both polar orbiting and geostationary imagery, including land cover, volcanic ash, dust, and clouds

  6. The LARES Space Experiment: LARES Orbit, Error Analysis and Satellite Structure

    Microsoft Academic Search

    Ignazio Ciufolini; Antonio Paolozzi; Erricos Pavlis; John Ries; Rolf Koenig; Richard Matzner; Giampiero Sindoni

    2010-01-01

    \\u000a The LARES space experiment, by the Italian Space Agency (ASI), is based on the launch of a new laser ranged satellite, called\\u000a LARES (LAser RElativity Satellite), using the new launch vehicle VEGA (Veicolo Europeo di Generazione. Avanzata, provided\\u000a by ESA). LARES will have an altitude of about 1,450 km, orbital inclination of about 71. 5? and nearly zero eccentricity. The

  7. The integration of the motion equations of low-orbiting earth satellites using Taylor's method

    NASA Astrophysics Data System (ADS)

    Krivov, A. V.; Chernysheva, N. A.

    1990-04-01

    A method for the numerical integration of the equations of motion for a satellite is proposed, taking the earth's oblateness and atmospheric drag into account. The method is based on Taylor's representation of the solution to the corresponding polynomial system. The algorithm for choosing the integration step and error estimation is constructed. The method is realized as a subrouting package. The method is applied to a low-orbiting earth satellite and the results are compared with those obtained using Everhart's method.

  8. Commercial free flyer satellites and orbital re-entry\\/recovery systems for low cost microgravity research

    Microsoft Academic Search

    John M. Cassanto; Robert B. Hobbs; Michael B. Bem

    2001-01-01

    Part of the next generation network of Space Transportation Systems will include unmanned, autonomous ``Free Flyer'' satellites with ground-controlled re-entry and recovery systems for low-cost biomedical and microgravity research. A commercial space requirement for the launch, LEO deployment and orbital recovery of low-cost research satellites will be an important function of spaceport operations and technology development in the next decade.

  9. Commercial free flyer satellites and orbital re-entry\\/recovery systems for low cost microgravity research

    Microsoft Academic Search

    John M. Cassanto; Robert B. Hobbs; Michael B. Bem

    2001-01-01

    Part of the next generation network of Space Transportation Systems will include unmanned, autonomous “Free Flyer” satellites with ground-controlled re-entry and recovery systems for low-cost biomedical and microgravity research. A commercial space requirement for the launch, LEO deployment and orbital recovery of low-cost research satellites will be an important function of spaceport operations and technology development in the next decade.

  10. A software package for the graphical simulation of the Global Positioning System's satellite orbits 

    E-print Network

    Martinez-Lopez, Eugenio

    1981-01-01

    /Computer Interaction CONCLUSION. 36 38 40 Recommendations for Further Research. 40 REFERENCES . VITA. 43 44 LIST OP TABLES Table KEPLERIAN ORBIT EQUATIONS. Page 9 II III FORTRAN LISTING FOR THE INITIAL AND MODIFIED SATELLITE GENERATING SECTIONS . 10...; however, the primary purpose of the work is to provide the user or system designer with a means of visualizing the system and generating flight profile data, using a visual/interactive model of either a section, or the complete satellite constellation...

  11. An approach to QoS-based routing for low Earth orbit satellite networks

    Microsoft Academic Search

    Hoang Nam Nguyen; Admela Jukan

    2000-01-01

    We propose a routing methodology for multi-hop low Earth orbit (LEO) satellite networks aiming at minimising the number of link handovers per connection, while at the same time satisfying QoS requirements. For the representation of the network topology, an approach with a graph method is used, where a new metric for inter-satellite links, called lifetime, is introduced. This metric is

  12. Undulation and anomaly estimation using Geos3 altimeter data without precise satellite orbits

    Microsoft Academic Search

    R. Rummel; R. H. Rapp

    1977-01-01

    The paper describes results obtained from the processing of 53 Geos-3 arcs of altimeter data obtained during the first weeks\\u000a after the launch of the satellite in April, 1975. The measurement from the satellite to the ocean surface was used to obtain\\u000a an approximate geoid undulation which was contaminated by long wavelength errors caused primarily by altimeter bias and orbit

  13. Relativistic effects for near-earth satellite orbit determination

    Microsoft Academic Search

    C. Huang; J. C. Ries; B. D. Tapley; M. M. Watkins

    1990-01-01

    The relativistic formulations for the equations which describe the motion of a near-Earth satellite are compared for two commonly used coordinate reference systems (RS). The discussion describes the transformation between the solar system barycentric RS and both the non-inertial and inertial geocentric RSs. A relativistic correction for the Earth's geopotential expressed in the solar system barycentric RS and the effect

  14. Tidal studies from the perturbations in satellite orbits

    Microsoft Academic Search

    A. Cazenave; S. Daillet; K. Lambeck

    1977-01-01

    The M2 and S2 ocean tides have been estimated by determining the perturbations caused in satellites by the action of the ocean tides. The contribution of the oceans to the total tidal potential (which includes the solid tide potential) must be understood to permit accurate calculation of the Love number and the phase lag of the tidal effective earth. Tide

  15. Simulation of interference between Earth stations and Earth-orbiting satellites

    NASA Technical Reports Server (NTRS)

    Bishop, D. F.

    1994-01-01

    It is often desirable to determine the potential for radio frequency interference between earth stations and orbiting spacecraft. This information can be used to select frequencies for radio systems to avoid interference or it can be used to determine if coordination between radio systems is necessary. A model is developed that will determine the statistics of interference between earth stations and elliptical orbiting spacecraft. The model uses orbital dynamics, detailed antenna patterns, and spectral characteristics to obtain accurate levels of interference at the victim receiver. The model is programmed into a computer simulation to obtain long-term statistics of interference. Two specific examples are shown to demonstrate the model. The first example is a simulation of interference from a fixed-satellite earth station to an orbiting scatterometer receiver. The second example is a simulation of interference from earth-exploration satellites to a deep-space earth station.

  16. The Development of Geostationary Microwave Observation in China

    NASA Astrophysics Data System (ADS)

    LU, Naimeng; GUO, Yang; GU, Songyan; WU, Xuebao; LI, Xiaoqing

    2015-04-01

    Great achievements have been made in the regime of microwave observation from polar orbiting meteorological satellites and their microwave data have been successfully used in the retrieval of precipitation and temperature/humidity profile, as well as data assimilation. But right now, there is no microwave observation in GEO due to its technical difficulty even through some plans such as GEM, GOMAS were proposed. The plan to develop microwave instruments for geostationary meteorological satellites have been approved by Chinese government and this presentation will introduce the status of its development, including the requirement consideration, microwave forward model simulation, the retrieval of precipitation, instrument specification, potential data application.. The followings are concluded in this presentation, •Microwave observation on GEO will greatly improve the capacity of current meteorological satellites •The 54GHz and 183GHz bands are on the top of the priority for temperature and humidity profiling, followed by 118, 425 and 325,380 GHz respectively. •Combined the 54 and 183 band together, better precipitation retrieval results could be expected •Regarding the strong convective precipitation retrieval, the 54GHz and 183GHz bands can provide basic information for precipitation retrieval and the improvement with additional window channels is not very significant. •The satisfied resolution for precipitation estimation is 5 to 10 Km and the tolerant value is 50km.

  17. Study on Orbital Decay of Near Earth Satellites with KS Orthogonal Elements

    NASA Astrophysics Data System (ADS)

    Ps, Sandeep

    STUDY ON ORBITAL DECAY OF NEAR EARTH SATELLITES WITH KS ORTHOGONAL ELEMENTS SANDEEP P S The knowledge of satellite orbit decay and its expected life prior to launch is necessary for mission planning purpose. Several sets of data for various parametric studies is sought quite often, it is necessary to minimize computational time involved for generating decay predictions, keeping the prediction accuracy normally good. A number of factors play dominant role in perturbation modelling for near earth satellites such as oblateness of the Earth, presence of the atmosphere, luni-solar attraction and solar radiation pressure. This paper concerns with the study of orbital decay of near earth satellites with KS orthogonal elements, which provide accurate orbit predictions at low computational time. Perturbations considered are due to oblateness of the Earth and the atmospheric drag. The Earth’s zonal harmonic terms J2 to J6 are included and the drag is modeled with an analytical diurnally oblate atmosphere. Effect of Earth’s geomagnetic and solar activity is included in density and density scale height computations. JACCHIA77 atmospheric model is utilized. The developed software is validated with the orbital data of decayed objects taken from www.space-track.org.

  18. Satellite-based quantum clock synchronization

    E-print Network

    Wang, Jieci; Jing, Jiliang; Fan, Heng

    2015-01-01

    We propose a practical satellite-based quantum clock synchronization scheme with dispersion cancellation and by taking into account effects of gravitational frequency shift of the Earth. Two frequency entangled pulses are employed to synchronize two clocks, one at a ground station and the other at a satellite. The time discrepancy of the two clocks is introduced into the pulses by moving mirrors and is extracted by measuring the coincidence rate of the pulses in the interferometer. We find that the pulses are distorted due to effects of the gravitational frequency shift when they propagate between the Earth and the satellite. It is shown that the coincidence rate as well as precision of the time discrepancy are remarkably affected by gravitational frequency shift effects both for the low earth orbits satellite and geostationary earth orbits satellite cases. We also find that the precision of the clock synchronization are sensitive to the source parameters and the altitude of the satellite. Our proposal can be...

  19. Meteorological Satellite Education Resources: Web-based Learning Modules, Initiatives, and the Environmental Satellite Resource Center (ESRC)

    NASA Astrophysics Data System (ADS)

    Schreiber-Abshire, W.; Dills, P.

    2008-12-01

    The COMET® Program (www.comet.ucar.edu) receives funding from NOAA NESDIS and the NPOESS Integrated Program Office (IPO), with additional contributions from the GOES-R Program Office and EUMETSAT, to directly support education and training efforts in the area of satellite meteorology. This partnership enables COMET to create educational materials of global interest on geostationary and polar- orbiting remote sensing platforms and their instruments, data, products, and operational applications. Over the last several years, COMET's satellite education programs have focused on the capabilities and applications of the upcoming next generation operational polar-orbiting NPP/NPOESS system and its relevance to operational forecasters and other user communities. COMET's activities have recently expanded to include education on the future Geostationary Operational Environmental Satellites (GOES-R). By partnering with experts from the Naval Research Laboratory, NOAA-NESDIS and various user communities, COMET stimulates greater utilization of both current and future satellite observations and products. In addition, COMET has broadened the scope of its online training to include materials on the EUMETSAT Polar-orbiting System (EPS) and Meteosat geostationary satellites. EPS represents an important contribution to the Initial Joint Polar System (IJPS) between NOAA and EUMETSAT, while Meteosat imaging capabilities provide an early look for the next generation GOES-R satellites. Also in collaboration with EUMETSAT, COMET is developing future modules on the joint NASA-CNES Jason altimetry mission and on satellite capabilities for monitoring the global climate. COMET also provides Spanish translations of relevant GOES materials in order to support the GEOSS (Global Earth Observation System of Systems) Americas effort, which is associated with the move of GOES-10 to provide routine satellite coverage over South America. This poster presentation provides an overview of COMET's recent satellite training efforts and publications, highlighting new materials relevant to both polar-orbiting and geostationary satellites. The presentation also showcases COMET's new community-drive Website, the Environmental Satellite Resource Center (ESRC), sponsored by the NPOESS IPO, NOAA, and NESDIS. The ESRC (www.meted.ucar.edu/ESRC) provides search capabilities and free access to a wide range of polar-orbiting and geostationary satellite information and training resources from multiple trusted sources, including MetEd (www.meted.ucar.edu).

  20. Space-based augmentation for global navigation satellite systems.

    PubMed

    Grewal, Mohinder S

    2012-03-01

    This paper describes space-based augmentation for global navigation satellite systems (GNSS). Space-based augmentations increase the accuracy and integrity of the GNSS, thereby enhancing users' safety. The corrections for ephemeris, ionospheric delay, and clocks are calculated from reference station measurements of GNSS data in wide-area master stations and broadcast via geostationary earth orbit (GEO) satellites. This paper discusses the clock models, satellite orbit determination, ionospheric delay estimation, multipath mitigation, and GEO uplink subsystem (GUS) as used in the Wide Area Augmentation System developed by the FAA. PMID:22481784

  1. Effect of 3rd-degree gravity harmonics and Earth perturbations on lunar artificial satellite orbits

    Microsoft Academic Search

    S. Tzirti; K. Tsiganis; H. Varvoglis

    2010-01-01

    In a previous work we studied the effects of (I) the J\\u000a 2 and C\\u000a 22 terms of the lunar potential and (II) the rotation of the primary on the critical inclination orbits of artificial satellites.\\u000a Here, we show that, when 3rd-degree gravity harmonics are taken into account, the long-term orbital behavior and stability\\u000a are strongly affected, especially for a

  2. Integrated orbit and attitude hardware-in-the-loop simulations for autonomous satellite formation flying

    NASA Astrophysics Data System (ADS)

    Park, Han-Earl; Park, Sang-Young; Kim, Sung-Woo; Park, Chandeok

    2013-12-01

    Development and experiment of an integrated orbit and attitude hardware-in-the-loop (HIL) simulator for autonomous satellite formation flying are presented. The integrated simulator system consists of an orbit HIL simulator for orbit determination and control, and an attitude HIL simulator for attitude determination and control. The integrated simulator involves four processes (orbit determination, orbit control, attitude determination, and attitude control), which interact with each other in the same way as actual flight processes do. Orbit determination is conducted by a relative navigation algorithm using double-difference GPS measurements based on the extended Kalman filter (EKF). Orbit control is performed by a state-dependent Riccati equation (SDRE) technique that is utilized as a nonlinear controller for the formation control problem. Attitude is determined from an attitude heading reference system (AHRS) sensor, and a proportional-derivative (PD) feedback controller is used to control the attitude HIL simulator using three momentum wheel assemblies. Integrated orbit and attitude simulations are performed for a formation reconfiguration scenario. By performing the four processes adequately, the desired formation reconfiguration from a baseline of 500-1000 m was achieved with meter-level position error and millimeter-level relative position navigation. This HIL simulation demonstrates the performance of the integrated HIL simulator and the feasibility of the applied algorithms in a real-time environment. Furthermore, the integrated HIL simulator system developed in the current study can be used as a ground-based testing environment to reproduce possible actual satellite formation operations.

  3. The Slinger - An in-orbit booster facility

    NASA Technical Reports Server (NTRS)

    Muller, R. M.

    1986-01-01

    The Slinger, a permanent facility that can be built and stationed in a low earth orbit and can reduce the cost of transporting satellites into geostationary orbit by a factor of three, is examined. The Slinger is described, giving its size, mass, capacity, and the construction of its tethers. Techniques for accelerating the tethers are discussed. The operation of the Slinger is examined, including its launching of a payload into geostationary transfer orbit (GTO) and its return to lower orbit. The Slinger's cycle time, its handling of lighter GTO payloads, and the effects of orbital precession and drag are briefly discussed. A possible reusable second stage based at the Slinger is discussed, and missions involving higher velocity and heavier payloads that can be helped by the Slinger are briefly considered along with the use of the Slinger to provide astronauts with 1 g and the use of a Slinger on the moon.

  4. Mars network: a Mars orbiting communications and navigation satellite constellation

    Microsoft Academic Search

    D. J. Bell; R. Cesarone; T. Ely; C. Edwards; S. Townes

    2000-01-01

    Mars has become the focus of an unprecedented series of missions spanning many years, involving numerous nations and evolving from robotic to human exploration. Elements will be dispersed widely in longitude and latitude over the surface of Mars. Some surface elements like rovers, balloons and airplanes will be mobile. Other elements like sample canisters will orbit Mars. Finally manned sites

  5. Simple satellite-tracking dual-band triangular-patch array antenna for ETS-VIII applications

    Microsoft Academic Search

    J. T. Sri Sumantyo; K. Ito; D. Delaune; T. Tanaka; H. Yoshimura

    2004-01-01

    The Japan Aerospace Exploration Agency (JAXA) will launch a geostationary satellite called Engineering Test Satellite-VIII (ETS-VIII) in 2005. ETS-VIII will conduct orbital experiments on mobile satellite communications at the S-band frequency, especially to support the development of a technology for the transmission and reception of multimedia information such as voice and images for land mobile systems. Various antennas have been

  6. Regenerative fuel cell study for satellites in GEO orbit

    Microsoft Academic Search

    Alexander Levy; Leslie L. Vandine; James K. Stedman

    1987-01-01

    Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr\\/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the

  7. New fire diurnal cycle characterizations to improve fire radiative energy assessments made from low-Earth orbit satellites sampling

    NASA Astrophysics Data System (ADS)

    Andela, N.; Kaiser, J. W.; van der Werf, G. R.; Wooster, M. J.

    2015-03-01

    Accurate near real time fire emissions estimates are required for air quality forecasts. To date, most approaches are based on satellite-derived estimates of fire radiative power (FRP), which can be converted to fire radiative energy (FRE) which is directly related to fire emissions. Uncertainties in these FRE estimations are often substantial. This is for a large part because the most often used low-Earth orbit satellite-based instruments like the MODerate-resolution Imaging Spectroradiometer (MODIS) have a relatively poor sampling of the usually pronounced fire diurnal cycle. In this paper we explore the spatial variation of this fire diurnal cycle and its drivers. Specifically, we assess how representing the fire diurnal cycle affects FRP and FRE estimations when using data collected at MODIS overpasses. Using data assimilation we explored three different methods to estimate hourly FRE, based on an incremental sophistication of parameterizing the fire diurnal cycle. We sampled data from the geostationary Meteosat Spinning Enhanced Visible and Infrared Imager (SEVIRI) at MODIS detection opportunities to drive the three approaches. The full SEVIRI time-series, providing full coverage of the diurnal cycle, were used to evaluate the results. Our study period comprised three years (2010-2012), and we focussed on Africa and the Mediterranean basin to avoid the use of potentially lower quality SEVIRI data obtained at very far off-nadir view angles. We found that the fire diurnal cycle varies substantially over the study region, and depends on both fuel and weather conditions. For example, more "intense" fires characterized by a fire diurnal cycle with high peak fire activity, long duration over the day, and with nighttime fire activity are most common in areas of large fire size (i.e., large burned area per fire event). These areas are most prevalent in relatively arid regions. Ignoring the fire diurnal cycle as done currently in some approaches caused structural errors, while generally overestimating FRE. Including information on the climatology of the fire diurnal cycle provided the most promising avenue to improve FRE estimations. This approach also improved the performance on relatively high spatiotemporal resolutions, although only when aggregating model results to coarser spatial and/or temporal scale good correlation was found with the full SEVIRI hourly reference dataset. In general model performance was best in areas of frequent fire and low errors of omission. We recommend the use of regionally varying fire diurnal cycle information within the Global Fire Assimilation System (GFAS) used in the Copernicus Atmosphere Monitoring Services, which will improve FRE estimates and may allow for further reconciliation of biomass burning emission estimates from different inventories.

  8. First TOA fluxes from the Geostationary Earth Radiation Budget (GERB) instrument

    NASA Astrophysics Data System (ADS)

    Bertrand, Cedric P.; Caprion, Didier; Clerbaux, Nicolas; Dewitte, Steven; Gonzalez, Luis; Ipe, Alessandro

    2004-11-01

    On 29th January 2004 the first Meteosat Second Generation satellite MSG-1, renamed Meteosat-8 (MS-8), commenced routine operations. MS-8 carries the new Spinning Enhanced Visible and Infra Red Imager (SEVIRI) and a Geostationary Earth Radiation Budget (GERB) radiometer. GERB provides valuable short- and long wave broadband measurements of the Earth in order to estimate the top-of-atmosphere radiation budget accurately. The unique feature of GERB in comparison with previous measurements of the Earth's radiation budget is its very fast temporal sampling (15 minutes) afforded by geostationary orbit. On the other hand, the GERB instrument only accounts for a crude spatial resolution (about 50 km at the sub-satellite point). Taking advantage of the synergy between the data from GERB and SEVIRI, we propose at the Royal Meteorological Institute of Belgium to merge the two data streams to produce near real-time estimates of the radiation budget for limited geographical regions at a 3x3 SEVIRI pixel resolution (the SEVIRI resolution is 3 km at satellite sub-point). Such fluxes aim to be used by the climate and numerical weather prediction (NWP) scientific communities through climate studies and validation/evaluation of the performance of NWP models over the region covered by MS-8.

  9. The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS): A Potential Canadian Mission Contribution to ILWS

    Microsoft Academic Search

    I. R. Mann; D. K. Milling; R. Rankin; R. Fedosejevs; Y. Y. Tsui; D. Knudsen; A. W. Yau; J. R. Wygant; J. F. Fennel; J. B. Blake; T. P. O'Brien; J. H. Clemmons; D. Summers; G. Sofko; D. Boteler

    2004-01-01

    The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission is presently undergoing Concept Study as a Canadian Space Agency satellite mission contribution to ILWS. The ORBITALS will provide a unique view of the largely previously unexplored inner magnetosphere. Its mission goal to \\

  10. The family of Quasi-satellite periodic orbits in the circular co-planar RTBP

    E-print Network

    Pousse, Alexandre; Vienne, Alain

    2014-01-01

    In the circular case of the coplanar Restricted Three-body Problem, we studied how the family of quasi-satellite (QS) periodic orbits allows to define an associated libration center. Using the averaged problem, we highlighted a validity limit of this one: for QS orbits with low eccentricities, the averaged problem does not correspond to the real problem. We do the same procedure to L 3 , L 4 and L 5 emerging periodic orbits families and remarked that for very high eccentricities F L4 and F L5 merge with F L3 which bifurcates to a stable family.

  11. Mercurial magnetic field waves measured by orbiting satellite

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-06-01

    Researchers working with NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging ( MESSENGER) spacecraft report the frequent detections of Kelvin-Helmholtz (KH) waves at the edge of the innermost planet's magnetosphere. In six different sets of magnetic field measurements made by the orbiter as it passed through Mercury's magnetopause, the boundary that separates the planet's magnetosphere from the solar wind plasma in the magnetosheath, Sundberg et al. detected the magnetic field oscillations characteristic of fully developed KH waves. These waves form when fuids of different speeds travel alongside each other—in this case, the magnetosphere and magnetosheath plasmas—and promote mixing of the plasmas on larger spatial, and shorter time, scales than diffusive transport. The observations, which span the frst 88 days of MESSENGER's time in orbit, bring Mercury alongside Earth, Saturn, and Venus as planets for which such KH waves are of importance.

  12. Tether Impact Rate Simulation and Prediction with Orbiting Satellites

    NASA Technical Reports Server (NTRS)

    Harrison, Jim

    2002-01-01

    Space elevators and other large space structures have been studied and proposed as worthwhile by futuristic space planners for at least a couple of decades. In June 1999 the Marshall Space Flight Center sponsored a Space Elevator workshop in Huntsville, Alabama, to bring together technical experts and advanced planners to discuss the current status and to define the magnitude of the technical and programmatic problems connected with the development of these massive space systems. One obvious problem that was identified, although not for the first time, were the collision probabilities between space elevators and orbital debris. Debate and uncertainty presently exist about the extent of the threat to these large structures, one in this study as large in size as a space elevator. We have tentatively concluded that orbital debris although a major concern not sufficient justification to curtail the study and development of futuristic new millennium concepts like the space elevators.

  13. GeoSTAR: a synthetic aperture microwave sounder for geostationary missions

    NASA Astrophysics Data System (ADS)

    Lambrigtsen, Bjorn H.; Wilson, William J.; Tanner, Alan B.; Kangaslahti, Pekka

    2005-01-01

    The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new microwave atmospheric sounder under development. It will bring capabilities similar to those now available on low-earth orbiting environmental satellites to geostationary orbit - where such capabilities have not been available. GeoSTAR will synthesize the multi-meter aperture needed to achieve the required spatial resolution, which will overcome the obstacle that has prevented a GEO microwave sounder from being implemented until now. The synthetic aperture approach has until recently not been feasible, due to the high power needed to operate the on-board high-speed massively parallel processing system required for 2D-synthesis, as well as a number of system and calibration obstacles. The development effort under way at JPL, with important contributions from the Goddard Space Flight Center and the University of Michigan, is intended to demonstrate the measurement concept and retire much of the technology risk. To that purpose a small ground based demo version of GeoSTAR is being constructed, which will be used to characterize system performance and test various calibration methods. This prototype development, which is being sponsored by NASA through its Instrument Incubator Program, will be completed in 2005. A GeoSTAR space mission can then be initiated. In parallel with the technology development, mission architecture studies are also under way in collaboration with the NOAA Office of System Development. In particular, the feasibility of incorporating GeoSTAR on the next generation of the geostationary weather satellites, GOES-R, is being closely examined. That would fill a long standing gap in the national weather monitoring capabilities.

  14. Simplified Orbit Determination Algorithm for Low Earth Orbit Satellites Using Spaceborne Gps Navigation Sensor

    NASA Astrophysics Data System (ADS)

    Tukaram Aghav, Sandip; Achyut Gangal, Shashikala

    2014-06-01

    In this paper, the main work is focused on designing and simplifying the orbit determination algorithm which will be used for Low Earth Orbit (LEO) navigation. The various data processing algorithms, state estimation algorithms and modeling forces were studied in detail, and simplified algorithm is selected to reduce hardware burden and computational cost. This is done by using raw navigation solution provided by GPS Navigation sensor. A fixed step-size Runge-Kutta 4th order numerical integration method is selected for orbit propagation. Both, the least square and Extended Kalman Filter (EKF) orbit estimation algorithms are developed and the results of the same are compared with each other. EKF algorithm converges faster than least square algorithm. EKF algorithm satisfies the criterions of low computation burden which is required for autonomous orbit determination. Simple static force models also feasible to reduce the hardware burden and computational cost.

  15. The Ohio State University Geometric and Orbital (adjustment) Program (OSUGOP) for satellite observations

    NASA Technical Reports Server (NTRS)

    Reilly, J. R.; Schwarz, C. R.; Whiting, M. C.

    1972-01-01

    A computer program, OSUGOP, developed for adjusting ground station coordinates from observations made to satellites by stations observing from the ground is outlined. The observations can be optical or ranges, and the adjustments can be performed in either the geometric or orbital mode. The program was developed in such a way that certain specific tasks can be performed without resorting to a complete solution.

  16. Satellite Orbit Determination Using a Single-Channel Global Positioning System Receiver by Mark L. Psiaki

    E-print Network

    Psiaki, Mark L.

    Satellite Orbit Determination Using a Single-Channel Global Positioning System Receiver by Mark L system has been analyzed, one that uses measurements from a single-channel Global Positioning System (GPS. Introduction The Global Positioning System (GPS) offers an attractive alternative to ground-based tracking

  17. ATTITUDE CONTROL AND STABILITY ANALYSIS OF SATELLITES IN EARTH AND MOON ORBIT

    E-print Network

    Gravdahl, Jan Tommy

    ATTITUDE CONTROL AND STABILITY ANALYSIS OF SATELLITES IN EARTH AND MOON ORBIT Thomas R. Krogstad predictive control scheme. In [16] a MPC was proposed for magnetically controlled spacecraft, but to the best on feedback from the angular velocity and attitude measurements, along with a measurement of the local

  18. The orbiting stellar ultraviolet spectrophotometer S59 in ESRO's TD1A satellite

    Microsoft Academic Search

    C. DE JAGER; R. Hoekstra; K. A. VAN DER HUCHT; T. M. Kamperman; H. J. Lamers; A. Hammerschlag; W. Werner; J. G. Emming

    1974-01-01

    The ultraviolet stellar spectrophotometer S59 of the Utrecht Astronomical Institute uses the stabilization properties of the ESRO TD-1A satellite. This spacecraft scans the sky along eliptic meridians with an orbital precession of one degree per day, thus covering the whole celestial sphere in half a year. This property is combined with a tracking system which points the spectrophotometer during four

  19. Orbital Diversity in Resource-Shared Satellite Communication Systems Above 10 GHz

    Microsoft Academic Search

    Emilio Matricciani

    1987-01-01

    The paper discusses orbital diversity (OD) used as the common resource in a satellite communication adaptive system affected by rain attenuation. To give quantitative results, a simulation at 20\\/30 GHz is performed with a mathematical model; also, some experimental results are shown. OD performance for a single site is first discussed. Then the probabilistic theory for adaptive systems is built

  20. Commercial free flyer satellites and orbital re-entry/recovery systems for low cost microgravity research

    NASA Astrophysics Data System (ADS)

    Cassanto, John M.; Hobbs, Robert B.; Bem, Michael B.

    2001-02-01

    Part of the next generation network of Space Transportation Systems will include unmanned, autonomous ``Free Flyer'' satellites with ground-controlled re-entry and recovery systems for low-cost biomedical and microgravity research. A commercial space requirement for the launch, LEO deployment and orbital recovery of low-cost research satellites will be an important function of spaceport operations and technology development in the next decade. Free flyer satellites will effectively complement the capabilities of intermittent manned Shuttle/SpaceHab missions and more sophisticated, long-duration, manned Mir and International Space Station missions. The USCORP initiative has been developed by ITA, Inc. to provide a commercially owned and operated orbital free flyer satellite and re-entry/recovery system to support microgravity, biomedical and life sciences research. The next generation low-cost, commercially viable orbital platform for microgravity research will depend on the application of existing technologies with flight-proven systems. This approach will ensure the operational reliability and low costs that will be required for commercial unmanned research missions. These commercial flight systems will be launched, remotely operated on orbit, and recovered from commercial spaceports utilizing next-generation advanced spaceport technologies and capabilities. .