Science.gov

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. Servicing communication satellites in geostationary orbit

    NASA Technical Reports Server (NTRS)

    Russell, Paul K.; Price, Kent M.

    1990-01-01

    The econmic benefits of a LEO space station are quantified by identifying alternative operating scenarios utilizing the space station's transportation facilities and assembly and repair facilities. Particular consideration is given to the analysis of the impact of on-orbit assembly and servicing on a typical communications satellite is analyzed. The results of this study show that on-orbit servicing can increase the internal rate of return by as much as 30 percent.

  3. 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.

  4. Effect of solar protons on the orbit of geostationary satellites

    NASA Astrophysics Data System (ADS)

    Herman, J.; Haerting, A.; Steinhauser, U.

    The forces acting on geostationary satellites are accurately modeled in operational orbit determination programs. The residuals of good-quality range data are typically 1 - 2 m over an interval of 2 days. In this paper, mission results from several three-axis-stabilized satellites are reported where, during periods of enhanced solar activity, the deviations between model and measurements increased by an order of magnitude or more. The causes and consequences for station keeping are analyzed. It is shown that there is a direct correlation between the disturbances in the orbit and the flux of energetic protons from the Sun. No energy dependence could be deduced, but all protons with energies greater than or equal to 4 MeV appear to trigger the disturbances. A quantitative analysis demonstrates that enhanced activity of the attitude thrusters is responsible for the unmodeled force. The protons primarily disturb the infrared earth sensors and the spurious attitude offset then causes unnecessary thruster firings. On the investigated spacecraft, the roll-thrusters are directed radially inwards, towards the Earth, with an orbit-tangential component of about 15%. From the amount of change in the eccentricity and in the semi-major axis over a disturbance, the expected ration between tangential- and radial-velocity components is verified. Finally, the extra fuel consumption during a period of high solar activity (such as the entire year 1991) is estimated.

  5. A Geostationary Earth Orbit Satellite Model Using Easy Java Simulation

    ERIC Educational Resources Information Center

    Wee, Loo Kang; Goh, Giam Hwee

    2013-01-01

    We develop an Easy Java Simulation (EJS) model for students to visualize geostationary orbits near Earth, modelled using a Java 3D implementation of the EJS 3D library. The simplified physics model is described and simulated using a simple constant angular velocity equation. We discuss four computer model design ideas: (1) a simple and realistic

  6. A Geostationary Earth Orbit Satellite Model Using Easy Java Simulation

    ERIC Educational Resources Information Center

    Wee, Loo Kang; Goh, Giam Hwee

    2013-01-01

    We develop an Easy Java Simulation (EJS) model for students to visualize geostationary orbits near Earth, modelled using a Java 3D implementation of the EJS 3D library. The simplified physics model is described and simulated using a simple constant angular velocity equation. We discuss four computer model design ideas: (1) a simple and realistic…

  7. The Benefits of Inclined-Orbit Operations for Geostationary Orbit Communication Satellites

    NASA Astrophysics Data System (ADS)

    Ma, Lihua

    2011-01-01

    Geostationary orbit (GEO) communication satellites can be extended in lifetime by switching to inclined-orbit operations. In this mode, a small amount of propellant is reserved to maintain the assigned orbit longitude. Inclination is allowed to build up at a rate of approximately 0.8○ per year. Developing these space resources can bring out a number of benefits. Besides communication application, these satellites can be used to construct navigation constellation of the Chinese Area Positioning System (CAPS). In this present paper, the realization way of communication and navigation applications is studied and the benefits and problems are explained.

  8. The use of satellites in non-goestationary orbits for unloading geostationary communication satellite traffic peaks. Volume 2: Technical report

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    The part of the geostationary (GEO) orbital arc used for United States domestic fixed, communications service is rapidly becoming filled with satellites. One of the factors currently limiting its utilization is that communications satellites must be designed to have sufficient capacity to handle peak traffic leads, and thus are under utilized most of the time. A solution is to use satellites in suitable non-geostationary orbits to unload the traffic peaks. Three different designs for a non-geostationary orbit communications satellite system are presented for the 1995 time frame. The economic performance is analyzed and compared with geostationary satellites for two classes of service, trunking and customer premise service. The result is that the larger payload of the non-geostationary satellite offsets the burdens of increased complexity and worse radiation environment to give improved economic performance. Depending on ground terminal configuration, the improved economic performance of the space segment may be offset by increased ground terminal expenses.

  9. Time Resolved Atmospheric Carbon Satellite Observations from Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Edwards, David; Worden, Helen

    This presentation describes proposed satellite carbon measurements from CHRONOS (Commercially Hosted spectroRadiometer Observations and New Opportunities for Science). The primary goal of this mission is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Both CO and CH4 are chemical precursors of tropospheric ozone pollution. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution. The CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth Venture TEMPO (Tropospheric Emissions: Monitoring of Pollution) mission were implemented concurrently, the resulting measurement suite would efficiently and expeditiously serve to address the science goals of the Decadal Survey proposed GEO-CAPE mission.

  10. Time Resolved Atmospheric Carbon Satellite Observations from Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Edwards, D. P.; Worden, H. M.; Deeter, M. N.; Worden, H. M.

    2013-12-01

    This presentation describes proposed satellite carbon measurements from CHRONOS (Commercially Hosted spectroRadiometer Observations and New Opportunities for Science). The primary goal of this mission is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Both CO and CH4 are chemical precursors of tropospheric ozone pollution. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution. The CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth Venture TEMPO (Tropospheric Emissions: Monitoring of Pollution) mission were implemented concurrently, the resulting measurement suite would efficiently and expeditiously serve to address the science goals of the Decadal Survey proposed GEO-CAPE mission.

  11. Attitude controller design for orbital target tracking of geostationary satellite under avoidance constraint

    NASA Astrophysics Data System (ADS)

    Park, Young-Woong; Bang, Hyochoong

    2011-04-01

    A coordinated attitude control problem is addressed for which a geostationary satellite should maintain communication with a ground station while simultaneously tracking space objects. The coordinated attitude control discussed in this study is related to the attitude maneuvers of a tracking satellite and to the orbital motion of targets placed in orbits of lower altitudes. Modified Rodrigues parameters are employed to avoid singularities even in the presence of large attitude maneuvers. The initial attitude error is calculated based upon an arbitrary initial configuration for the target tracking, so that a sequential tracking from one to another target can be achieved easily. Additionally, avoidance maneuvers aimed at protecting sensitive onboard sensors from the Sun and the Moon are designed using the so-called navigation function. When the avoidance areas are on the transient path due to the coordinated attitude maneuver command, the maneuver is performed with no violation against the given constraint areas by adopting the navigation function.

  12. Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

    PubMed Central

    Kim, Ghangho; Kim, Chongwon; Kee, Changdon

    2015-01-01

    A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO) satellite using single-epoch measurements from a Global Positioning System (GPS) receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS). Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF) tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state. PMID:25835299

  13. Digital cloud stereography from geostationary orbit

    NASA Technical Reports Server (NTRS)

    Dalton, J. T.; Desjardins, M. L.; Hasler, A. F.; Minzner, R. A.

    1979-01-01

    It has been demonstrated that geostationary satellite imagery provides an effective means of extracting two-dimensional cloud motion wind measurements over large areas. The addition of cloud height information is necessary, however, for the proper assignment of altitude to the wind vectors. This paper discusses the methodology and accuracy of extracting multilevel cloud motion measurements from stereo digital imagery acquired from geostationary orbit.

  14. 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.

  15. 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.

  16. Ephemeris calculation and orbit determination of geostationary satellites, using Taylor series integration

    NASA Astrophysics Data System (ADS)

    Montenbruck, Oliver

    1991-02-01

    It is shown that Taylor series integration allows problems of celestial mechanics for interplanetary orbits to be solved with relatively simple orbit models. The method is adapted to the computation of satellite orbits. A new implementation concept is included, which allows a programmation of the equations of motion. It offers simultaneously extension possibilities, which are necessary for the computation of special terms of the power function. The linking of Sun and Moon ephemeris for the treatment of gavitational disturbances of the satellite orbit is used as an example. This concept is represented with the principles of Taylor series integration, and compared with variants of the process. The power spectrum of the method is examined for disturbed and undisturbed Kepler orbits.

  17. Electric propulsion for geostationary orbit insertion

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; Curran, Francis M.; Myers, Roger M.

    1995-01-01

    Solar electric propulsion (SEP) technology is already being used for geostationary satellite stationkeeping to increase payload mass. By using this same technology to perform part of the orbit transfer additional increases in payload mass can be achieved. Advanced chemical and N2H4 arcjet systems are used to increase the payload mass by performing stationkeeping and part of the orbit transfer. Four mission options are analyzed which show the impact of either sharing the orbit transfer between chemical and SEP systems or having either complete the transfer alone. Results show that for an Atlas 2AS payload increases in net mass (geostationary satellite mass less wet propulsion system mass) of up to 100 kg can be achieved using advanced chemical for the transfer and advanced N2H4 arcjets for stationkeeping. An additional 100 kg can be added using advanced N2H4 arcjets for part of a 40 day orbit transfer.

  18. Astrometry and Geostationary Satellites in Venezuela

    NASA Astrophysics Data System (ADS)

    Lacruz, E.; Abad, C.

    2015-10-01

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

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

    NASA Astrophysics Data System (ADS)

    Zakek, 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 Eyjafjallajkull 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.

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

    NASA Astrophysics Data System (ADS)

    Zakek, 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 Eyjafjallajkull 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.

  1. Impact of Non-geostationary Orbits on PASS

    NASA Technical Reports Server (NTRS)

    Estabrook, Polly; Motamedi, Masoud

    1990-01-01

    The use of satellites in non-geostationary orbits (NGO) for PASS (Personal Access Satellite System) is discussed. The following subject areas are covered: (1) orbit parameters (circular and elliptical orbit characteristics); (2) link characteristics (Doppler shift, propagation loss, CONUS coverage antenna, multibeam antenna gain, and impact on link equations); (3) number of satellites required for continuous CONUS coverage (circular and elliptical orbit results); and (4) advantages and disadvantages of NGOs.

  2. 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.

  3. 78 FR 14952 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-08

    ... Electronic Comment Filing System (ECFS). See Electronic Filing of Documents in Rulemaking Proceedings, 63 FR... COMMISSION 47 CFR Part 2 Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service... of Earth Stations Aboard Aircraft (ESAA) in the 14.0-14.5 GHz band from secondary to primary...

  4. 78 FR 19172 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ..., FR Doc. 2013-04429, on page 14952, column 1, correct the DATES section to read as follows: DATES... COMMISSION 47 CFR Parts 2 and 25 Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service... proposed rule that appeared in the Federal Register of March 8, 2013. The document proposed rules for...

  5. Application of unscented filtering in analytical dynamic orbit determination for Geostationary satellite surveillance

    NASA Astrophysics Data System (ADS)

    Roh, Kyoung-Min; Park, Eunseo; Choi, Byung Kyu

    The neutral atmosphere introduces a time delay in the propagation of GPS signals in the microwave frequencies due to refraction effects. To project this delay in a slant direction towards the satellite position, various mapping functions are proposed. As 90KEYWORDS: GPS based navigation; Tropospheric range error; Hydrostatic Mapping Function Dr. K. Parameswaran is supported by CSIR through Emeritus Scientist Scheme. *Corresponding author: cs ureshraju@vssc.gov.in

  6. 47 CFR 74.643 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Interference to geostationary-satellites. 74... Television Broadcast Auxiliary Stations 74.643 Interference to geostationary-satellites. Applicants and... geostationary-satellites....

  7. 47 CFR 74.643 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Interference to geostationary-satellites. 74... Television Broadcast Auxiliary Stations 74.643 Interference to geostationary-satellites. Applicants and... geostationary-satellites....

  8. Geostationary Meteorological Satellite-5 (GMS-5)

    NASA Technical Reports Server (NTRS)

    Horii, M.

    1991-01-01

    The Geostationary Meteorological Satellite (GMS-5), which is being developed by the National Space Development Agency of Japan (NASDA), is the fifth geostationary, spin stabilized, weather satellite. Its purposes are to observe cataclysmic events such as hurricanes, typhoons, and regional weather phenomena; to relay meteorological data from surface collection points to the Data Processing Center in Japan; and to transmit processing imaging data for facsimile reproduction. The satellite will be launched from the Tanegashima Space Center (TaSC) in Japan by a type H-II launch vehicle. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. The coverage will consist of the 26-m antennas as prime and the 34-m antenna at Madrid as backup support for launch through drift orbit. Maximum support will consist of two 8-hour tracks per station for a seven day period, plus 23 days of contingency support from all complexes. Information is given in tabular form for DSN support, frequency assignments, telemetry, command and tracking station responsibility.

  9. The operational feasibility of orbit and attitude determination for the Geostationary Operational Environmental Satellite (SMS/GEOS) using only imagery data

    NASA Technical Reports Server (NTRS)

    Mack, E.; Jurotich, M.; Remondi, B.

    1978-01-01

    Experimental results from three evaluation periods on three geostationary spacecraft (SMS-2, GOES-1, and GOES-2) are presented. It is shown that using existing landmark extraction and identification techniques (1) for east geostationary spacecraft, a high quality orbit and attitude state is maintained with imagery data only, and (2) for west geostationary spacecraft, a high quality orbit and attitude state is recovered with imagery data only in approximately seven days.

  10. Spacecraft Charging in Geostationary Transfer Orbit

    NASA Technical Reports Server (NTRS)

    Parker, Linda Neergaard; Minow, Joseph I.

    2014-01-01

    The 700 km x 5.8 Re orbit of the two Van Allen Probes spacecraft provide a unique opportunity to investigate spacecraft 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.

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

    SciTech Connect

    Parrot, M.; Gaye, C.A.

    1994-11-15

    In this paper the authors summarize data taken by the wave experiment on the GEOS 2 satellite. This instrument looked at extremely low frequency emissions from a geostationary orbit. The authors do a statistical study of the observed ELF emissions, and in particular discuss chorus emissions, which with hiss and electron cyclotron emissions are the prominent low frequency wave features.

  12. Small Aperture Telescope Observations of Co-located Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Scott, R.; Wallace, B.

    As geostationary orbit (GEO) continues to be populated, satellite operators are increasing usage of co-location techniques to maximize usage of fewer GEO longitude slots. Co-location is an orbital formation strategy where two or more geostationary satellites reside within one GEO stationkeeping box. The separation strategy used to prevent collision between the co-located satellites generally uses eccentricity (radial separation) and inclination (latitude separation) vector offsets. This causes the satellites to move in relative motion ellipses about each other as the relative longitude drift between the satellites is near zero. Typical separations between the satellites varies from 1 to 100 kilometers. When co-located satellites are observed by optical ground based space surveillance sensors the participants appear to be separated by a few minutes of arc or less in angular extent. Under certain viewing geometries, these satellites appear to visually conjunct even though the satellites are, in fact, well separated spatially. In situations where one of the co-located satellites is more optically reflective than the other, the reflected sunglint from the more reflective satellite can overwhelm the other. This less frequently encountered issue causes the less reflective satellite to be glint masked in the glare of the other. This paper focuses on space surveillance observations on co-located Canadian satellites using a small optical telescope operated by Defence R&D Canada - Ottawa. The two above mentioned problems (cross tagging and glint masking) are investigated and we quantify the results for Canadian operated geostationary satellites. The performance of two line element sets when making in-frame CCD image correlation between the co-located satellites is also examined. Relative visual magnitudes between the co-located members are also inspected and quantified to determine the susceptibility of automated telescopes to glint masking of co-located satellite members.

  13. European small geostationary communications satellites

    NASA Astrophysics Data System (ADS)

    Sun, Wei, , Dr.; Ellmers, Frank; Winkler, Andreas; Schuff, Herbert; Sansegundo Chamarro, Manuel Julin

    2011-04-01

    Hispasat Advanced Generation 1 (HAG1) is the first satellite using the SGEO platform, which is under the development in the ESA Artes-11 program. Since the last presentation in the IAC 2007, a European industrial consortium led by OHB has completed the mission and spacecraft design. The platform Preliminary Design Review has been carried out in May 2008. The customer for the first mission is a commercial operatorHispasat. The contract was signed in December 2008 and the satellite will be launched in 2012. To give confidence to the customer, SGEO platform will use up to date flight proven technologies. HAG1 carries 20/24 Ku-band and 3/5 Ka-band transponders to provide commercial services. Some innovative payload technologies will also be flown on board of HAG1 to gain in-orbit heritage. SGEO has also been selected as the baseline platform for the ESA Data Relay Satellite (EDRS). Phase-A study has just kicked off in January 2009. The targeted launch date is 2013. Heinrich Hertz will also use the SGEO platform. Heinrich Hertz is funded by the German Space Agency (DLR) and provides flight opportunities for technologies and components developed by the German Space Industry. With the HAG1 contract in hand, and EDRS and Heinrich Hertz in the line, OHB with its partners has the confidence that it will be able to speed up the product development of the SGEO platform for potential customers in the commercial market. This paper will first present the updated platform design and the status of the product development will be followed with the introduction of innovative payload technologies on board the first missionHAG1 and ended with the mission concepts of EDRS and Heinrich Hertz missions.

  14. Long-term evolution of near-geostationary orbits

    NASA Astrophysics Data System (ADS)

    van der Ha, J. C.

    1986-06-01

    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 harmonics of the earth's potential field up to the fourth degree, as well as the solar radiation force. The algebraic computations have been carried out by an automated Poisson series manipulation. Extremely compact expressions could be established after manually recombining the computer-generated results in terms of a few well-selected parameters. The results obtained are of particular interest for predicting the motion of geostationary spacecraft after their useful lifetime has expired and stationkeeping maneuvers are no longer executed. The validity of the model presented has been evaluated by a comparison with numerical results obtained for the European Space Agency's GEOS-2 satellite, which is at present orbiting about 260 km above geostationary altitude.

  15. Surface albedo based on geostationary satellite observations

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Surface albedo is the fraction of incoming solar radiation reflected by the land surface, and therefore is 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) is implementing the Geostationary Surface Albedo (GSA; Lattanzio and Govaerts, 2010) algorithm for GOES data in support of an activity of 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 retrieve surface albedo by processing day-time, cloud-free geostationary observations from a single visible band. Currently, the GSA algorithm generates products operationally at EUMETSAT using geostationary data from satellites at 0 and 63E and at JMA using 140E geostationary data. To support development of an aggregate global albedo product, NCDC will apply the GSA algorithm to data from GOES-E (75W) and GOES-W (135W). For the GOES implementation, raw GOES observations are calibrated against AVHRR reflectance data available in PATMOS-x. Surface angular anisotropy is then 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 additionally requires ancillary total column ozone and water vapor values, which for the GOES implementation are acquired from the 20th Century Reanalysis V2 data set provided by the NOAA/OAR/ESRL PSD. The GSA algorithm produces a 10-day composite surface albedo map. This product will initially be developed for the period 2000-2003. Later, it will be applied to the complete GOES data collection (1978-present) as part of NOAA's Climate Data Record Program.

  16. 47 CFR 25.278 - Additional coordination obligation for non-geostationary and geostationary satellite systems in...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Service for their feeder link operations shall coordinate their operations with licensees of geostationary...-geostationary satellite systems for feeder link operations shall coordinate their operations with the...

  17. 47 CFR 25.278 - Additional coordination obligation for non-geostationary and geostationary satellite systems in...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Service for their feeder link operations shall coordinate their operations with licensees of geostationary...-geostationary satellite systems for feeder link operations shall coordinate their operations with the...

  18. 47 CFR 25.278 - Additional coordination obligation for non-geostationary and geostationary satellite systems in...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... service for their feeder link operations shall coordinate their operations with licensees of geostationary...-geostationary satellite systems for feeder link operations shall coordinate their operations with the...

  19. 47 CFR 25.278 - Additional coordination obligation for non-geostationary and geostationary satellite systems in...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... service for their feeder link operations shall coordinate their operations with licensees of geostationary...-geostationary satellite systems for feeder link operations shall coordinate their operations with the...

  20. 47 CFR 25.278 - Additional coordination obligation for non-geostationary and geostationary satellite systems in...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... service for their feeder link operations shall coordinate their operations with licensees of geostationary...-geostationary satellite systems for feeder link operations shall coordinate their operations with the...

  1. 47 CFR 25.261 - Procedures for avoidance of in-line interference events for Non Geostationary Satellite Orbit...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... two or more satellite networks with an operating Earth station of one of these networks in such a way... at the Earth station. (c) Default procedure. If no agreed coordination exists between two or more... of one or more typical earth stations. All parties are required to coordinate in good faith....

  2. 47 CFR 25.261 - Procedures for avoidance of in-line interference events for Non Geostationary Satellite Orbit...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... two or more satellite networks with an operating Earth station of one of these networks in such a way... at the Earth station. (c) Default procedure. If no agreed coordination exists between two or more... of one or more typical earth stations. All parties are required to coordinate in good faith....

  3. 47 CFR 25.261 - Procedures for avoidance of in-line interference events for Non Geostationary Satellite Orbit...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... two or more satellite networks with an operating Earth station of one of these networks in such a way... at the Earth station. (c) Default procedure. If no agreed coordination exists between two or more... of one or more typical earth stations. All parties are required to coordinate in good faith....

  4. 47 CFR 25.261 - Procedures for avoidance of in-line interference events for Non Geostationary Satellite Orbit...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... two or more satellite networks with an operating Earth station of one of these networks in such a way... at the Earth station. (c) Default procedure. If no agreed coordination exists between two or more... of one or more typical earth stations. All parties are required to coordinate in good faith....

  5. 47 CFR 25.261 - Procedures for avoidance of in-line interference events for Non Geostationary Satellite Orbit...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... two or more satellite networks with an operating Earth station of one of these networks in such a way... at the Earth station. (c) Default procedure. If no agreed coordination exists between two or more... of one or more typical earth stations. All parties are required to coordinate in good faith....

  6. Three-axis attitude control for a geostationary satellite

    NASA Technical Reports Server (NTRS)

    Freeman, H. R.

    1976-01-01

    The Applications Technology Satellite-6 was successfully launched into a geostationary orbit in May, 1974. Since that time, its attitude control subsystem has routinely demonstrated its ability to perform precision pointing and precision closed loop maneuvers. This paper describes the ATS-6 attitude control subsystem. The requirements imposed by the spacecraft mission objectives are outlined, and functional descriptions of the principal attitude control subsystem components and control laws are presented. The paper concludes with a summary comparison of in-orbit performance relative to its specified performance requirements.

  7. Local oscillator distribution using a geostationary satellite

    NASA Technical Reports Server (NTRS)

    Bardin, Joseph; Weinreb, Sander; Bagri, Durga

    2004-01-01

    A satellite communication system suitable for distribution of local oscillator reference signals for a widely spaced microwave array has been developed and tested experimentally. The system uses a round-trip correction method of the satellite This experiment was carried out using Telstar-5, a commercial Ku-band geostationary satellite. For this initial experiment, both earth stations were located at the same site to facilitate direct comparison of the received signals. The local oscillator reference frequency was chosen to be 300MHz and was sent as the difference between two Ku-band tones. The residual error after applying the round trip correction has been measured to be better than 3psec for integration times ranging from 1 to 2000 seconds. For integration times greater then 500 seconds, the system outperforms a pair of hydrogen masers with the limitation believed to be ground-based equipment phase stability. The idea of distributing local oscillators using a geostationary satellite is not new; several researchers experimented with this technique in the eighties, but the achieved accuracy was 3 to 100 times worse than the present results. Since substantially and the performance of various components has improved. An important factor is the leasing of small amounts of satellite communication bandwidth. We lease three 100kHz bands at approximately one hundredth the cost of a full 36 MHz transponder. Further tests of the system using terminal separated by large distances and comparison tests with two hydrogen masers and radio interferometry is needed.

  8. 47 CFR 78.106 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Interference to geostationary-satellites. 78...-satellites. Applicants and licensees must comply with 101.145 of this chapter to minimize the potential of interference to geostationary-satellites....

  9. 47 CFR 78.106 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Interference to geostationary-satellites. 78...-satellites. Applicants and licensees must comply with 101.145 of this chapter to minimize the potential of interference to geostationary-satellites....

  10. Multicolour Optical Photometry of Active Geostationary Satellites

    NASA Astrophysics Data System (ADS)

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

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

  11. Towards high temporal and moderate spatial resolutions in the remote sensing retrieval of evapotranspiration by combining geostationary and polar orbit satellite data

    NASA Astrophysics Data System (ADS)

    Barrios, Jos Miguel; Ghilain, Nicolas; Arboleda, Alirio; Gellens-Meulenberghs, Franoise

    2014-05-01

    Evapotranspiration (ET) is the water flux going from the surface into the atmosphere as result of soil and surface water evaporation and plant transpiration. It constitutes a key component of the water cycle and its quantification is of crucial importance for a number of applications like water management, climatic modelling, agriculture monitoring and planning, etc. Estimating ET is not an easy task; specially if large areas are envisaged and various spatio-temporal patterns of ET are present as result of heterogeneity in land cover, land use and climatic conditions. In this respect, spaceborne remote sensing (RS) provides the only alternative to continuously measure surface parameters related to ET over large areas. The Royal Meteorological Institute (RMI) of Belgium, in the framework of EUMETSAT's "Land Surface Analysis-Satellite Application Facility" (LSA-SAF), has developed a model for the estimation of ET. The model is forced by RS data, numerical weather predictions and land cover information. The RS forcing is derived from measurements by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) satellite. This ET model is operational and delivers ET estimations over the whole field of view of the MSG satellite (Europe, Africa and Eastern South America) (http://landsaf.meteo.pt) every 30 minutes. The spatial resolution of MSG is 3 x 3 km at subsatellite point and about 4 x 5 km in continental Europe. The spatial resolution of this product may constrain its full exploitation as the interest of potential users (farmers and natural resources scientists) may lie on smaller spatial units. This study aimed at testing methodological alternatives to combine RS imagery (geostationary and polar orbit satellites) for the estimation of ET such that the spatial resolution of the final product is improved. In particular, the study consisted in the implementation of two approaches for combining the current ET estimations with RS data containing information over vegetation parameters and captured by polar orbit spaceborne sensors. The first tested approach consisted in forcing the operational ET algorithm with RS measurements obtained from a moderate spatial resolution sensor. The variables with improved spatial resolution were leaf area index and albedo. Other variables of the model remained unchanged with respect to the operational version. In the second approach, a two phases procedure was implemented. Firstly, a preliminary approximation of ET was obtained as a function of solar radiation, air temperature and a vegetation index. The value was then statistically adjusted on the basis of the ET estimations by the operational algorithm. The results of implementing the different approaches were tested against eddy covariance ET derived from measurements in Fluxnet towers spread across Europe and representing different landscape characteristics. The analysis allowed the identification of pros and cons of the tested methodological approaches as well as their performance in different land cover arrangements.

  12. Normalization and calibration of geostationary satellite radiances for the International Satellite Cloud Climatology Project

    NASA Technical Reports Server (NTRS)

    Desormeaux, Yves; Rossow, William B.; Brest, Christopher L.; Campbell, G. G.

    1993-01-01

    Procedures are described for normalizing the radiometric calibration of image radiances obtained from geostationary weather satellites that contributed data to the International Satellite Cloud Climatology Project. The key step is comparison of coincident and collocated measurements made by each satellite and the concurrent AVHRR on the 'afternoon' NOAA polar-orbiting weather satellite at the same viewing geometry. The results of this comparison allow transfer of the AVHRR absolute calibration, which has been established over the whole series, to the radiometers on the geostationary satellites. Results are given for Meteosat-2, 3, and 4, for GOES-5, 6, and 7, for GMS-2, 3, and 4 and for Insat-1B. The relative stability of the calibrations of these radiance data is estimated to be within +/- 3 percent; the uncertainty of the absolute calibrations is estimated to be less than 10 percent. The remaining uncertainties are at least two times smaller than for the original radiance data.

  13. 47 CFR 78.106 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Interference to geostationary-satellites. 78.106 Section 78.106 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations 78.106 Interference to geostationary-satellites. Applicants and licensees must...

  14. 47 CFR 78.106 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Interference to geostationary-satellites. 78.106 Section 78.106 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations 78.106 Interference to geostationary-satellites. Applicants and licensees must...

  15. 47 CFR 78.106 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Interference to geostationary-satellites. 78.106 Section 78.106 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations 78.106 Interference to geostationary-satellites. Applicants and licensees must...

  16. Remote Sensing from Geostationary Orbit: GEO TROPSAT, A New Concept for Atmospheric Remote Sensing

    NASA Technical Reports Server (NTRS)

    Little, Alan D.; Neil, Doreen O.; Sachse, Glen W.; Fishman, Jack; Krueger, Arlin J.

    1997-01-01

    The Geostationary Tropospheric Pollution Satellite (GEO TROPSAT) mission is a new approach to measuring the critical constituents of tropospheric ozone chemistry: ozone, carbon monoxide, nitrogen dioxide, and aerosols. The GEO TROPSAT mission comprises a constellation of three instruments flying as secondary payloads on geostationary communications satellites around the world. This proposed approach can significantly reduce the cost of getting a science payload to geostationary orbit and also generates revenue for the satellite owners. The geostationary vantage point enables simultaneous high temporal and spatial resolution measurement of tropospheric trace gases, leading to greatly improved atmospheric ozone chemistry knowledge. The science data processing, conducted as a research (not operational) activity, will provide atmospheric trace gas data many times per day over the same region at better than 25 km ground footprint. The high temporal resolution identifies short time scale processes, diurnal variations, seasonal trends, and interannual variation.

  17. Sea surface temperature - Observations from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Bates, J. J.; Smith, W. L.

    1985-01-01

    Multispectral image data acquired from the VISSR atmospheric sounder (VAS) on the geostationary GOES satellites were used to estimate sea surface temperatures (SST). A procedure was developed to screen VAS visible and infrared data for cloud-free regions for estimation of SST from the clear infrared radiances. A data set of matches between the VAS radiances and high quality buoy estimates of SST was produced. A linear regression analysis of these matches was performed to generate an empirical algorithm relating the VAS window channel brightness temperatures to the estimates of SST recorded by NOAA fixed environment buoys. Daily maps of SST during Hurricanes Alicia (1983) and Debbie (1982) demonstrated the ability of VAS to monitor air-sea interactions at high temporal and spatial scales.

  18. Estimating Solar Irradiance using a Geostationary Satellite

    NASA Astrophysics Data System (ADS)

    Urquhart, Bryan Glenn

    A method to estimate global horizontal irradiance (GHI) at the surface using a geostationary satellite is presented. The spatial variation of ground and cloud albedo of California is characterized in the 0.55-0.75 im wavelength spectral region by analyzing a series of images from the visible channel on the GOES West satellite. Using these two characteristic albedo maps a cloud index is generated for each pixel in subsequent images as an estimate of the cloud fraction in that pixel. The cloud index is converted into a clear sky index which is then coupled with the modeled GHI under a clear sky to generate estimates of the GHI under the current cloud conditions. The model was applied to 914 images over 65 days and validated with ground truth measurements in California. The mean bias difference from 119 stations in the California Irrigation Management Information System was 6.7 W/m 2 (3.2%) and the root mean square difference was 78.6 W/m2 (21.9%) which is consistent with previously reported results for satellite algorithms. A Matlab-Java code to execute the model is documented.

  19. Polar mesospheric clouds seen from geostationary orbit

    NASA Astrophysics Data System (ADS)

    Gadsden, M.

    2000-01-01

    The visible image data archived by EUMETSAT have been examined to discover if the whole-Earth images acquired from the geostationary meteorological satellite, METEOSAT, show polar mesospheric clouds above the limb. Images from the northern summer of 1995 show polar mesospheric clouds frequently in June and July at the highest visible latitude (81.3N) and on occasion extending down as low as 65N. A first-look at days through the summer shows that there is no marked forward-scatter of sunlight from the clouds and that it is possible to choose times of day throughout the year when there will be no interference to the detection of polar mesospheric clouds from ghost images of the Sun or from light scattered in the optical system of the radiometer. With over 20 years of data in the archive, available for both northern and southern hemispheres, taken under controlled conditions, studies of the climatology of polar mesospheric clouds can develop significantly.

  20. Radar for Monitoring Hurricanes from Geostationary Orbit

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Durden, Stephen; Huang, John; Lou, Michael; Smith, Eric; Rahmat-Samii, Yahya

    2004-01-01

    A document describes a scanning Doppler radar system to be placed in a geostationary orbit for monitoring the three-dimensional structures of hurricanes, cyclones, and severe storms in general. The system would operate at a frequency of 35 GHz. It would include a large deployable spherical antenna reflector, instead of conventional paraboloidal reflectors, that would allow the reflector to remain stationary while moving the antenna feed(s), and thus, create a set of scanning antenna beams without degradation of performance. The radar would have separate transmitting and receiving antenna feeds moving in spiral scans over an angular excursion of 4 from the boresight axis to providing one radar image per hour of a circular surface area of 5,300-km diameter. The system would utilize a real-time pulse-compression technique to obtain 300-m vertical resolution without sacrificing detection sensitivity and without need for a high-peakpower transmitter. An onboard data-processing subsystem would generate three-dimensional rainfall reflectivity and Doppler observations with 13-km horizontal resolution and line-of-sight Doppler velocity at a precision of 0.3 m/s.

  1. 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.

  2. Geostationary payload concepts for personal satellite communications

    NASA Astrophysics Data System (ADS)

    Benedicto, J.; Rinous, P.; Roberts, I.; Roederer, A.; Stojkovic, I.

    This paper reviews candidate satellite payload architectures for systems providing world-wide communication services to mobile users equipped with hand-held terminals based on large geostationary satellites. There are a number of problems related to the payload architecture, on-board routing and beamforming, and the design of the S-band Tx and L-band Rx antenna and front ends. A number of solutions are outlined, based on trade-offs with respect to the most significant performance parameters such as capacity, G/T, flexibility of routing traffic to beams and re-configuration of the spot-beam coverage, and payload mass and power. Candidate antenna and front-end configurations were studied, in particular direct radiating arrays, arrays magnified by a reflector and active focused reflectors with overlapping feed clusters for both transmit (multimax) and receive (beam synthesis). Regarding the on-board routing and beamforming sub-systems, analog techniques based on banks of SAW filters, FET or CMOS switches and cross-bar fixed and variable beamforming are compared with a hybrid analog/digital approach based on Chirp Fourier Transform (CFT) demultiplexer combined with digital beamforming or a fully digital processor implementation, also based on CFT demultiplexing.

  3. Geostationary payload concepts for personal satellite communications

    NASA Technical Reports Server (NTRS)

    Benedicto, J.; Rinous, P.; Roberts, I.; Roederer, A.; Stojkovic, I.

    1993-01-01

    This paper reviews candidate satellite payload architectures for systems providing world-wide communication services to mobile users equipped with hand-held terminals based on large geostationary satellites. There are a number of problems related to the payload architecture, on-board routing and beamforming, and the design of the S-band Tx and L-band Rx antenna and front ends. A number of solutions are outlined, based on trade-offs with respect to the most significant performance parameters such as capacity, G/T, flexibility of routing traffic to beams and re-configuration of the spot-beam coverage, and payload mass and power. Candidate antenna and front-end configurations were studied, in particular direct radiating arrays, arrays magnified by a reflector and active focused reflectors with overlapping feed clusters for both transmit (multimax) and receive (beam synthesis). Regarding the on-board routing and beamforming sub-systems, analog techniques based on banks of SAW filters, FET or CMOS switches and cross-bar fixed and variable beamforming are compared with a hybrid analog/digital approach based on Chirp Fourier Transform (CFT) demultiplexer combined with digital beamforming or a fully digital processor implementation, also based on CFT demultiplexing.

  4. Time transfer using geostationary satellites: Implementation of a Kalman filter

    NASA Technical Reports Server (NTRS)

    Meyer, F.

    1994-01-01

    Since 1988, various experiments have shown that the TV signals transmitted by direct TV satellites may easily be used to perform time transfers at the level of a few tens of nanoseconds, the main source of error being the uncertainty on the satellite position. We first present the two methods used in our experiment to reduce the effects of the satellite residual motion: the first one consists in estimating the longitude variations of the satellite and then using this information to improve other measurements. This allows reducing the uncertainty to values between 9 and 50 nanoseconds according to the position of the involved stations. In the second method we determine the satellite position by using the data collected by three calibrated stations. Time transfer between each of these stations and a fourth one has been shown to be achievable at the precision level of ten nanoseconds. A new approach based on the use of a Kalman filter is proposed in order to take into account the dynamics of the geostationary satellite. The precisions on orbital elements and clock differences and rates determination given by the first simulated applications of the Kalman filter are presented and compared to those obtained by the other methods.

  5. 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.

  6. ESA personal communications and digital audio broadcasting systems based on non-geostationary satellites

    NASA Technical Reports Server (NTRS)

    Logalbo, P.; Benedicto, J.; Viola, R.

    1993-01-01

    Personal Communications and Digital Audio Broadcasting are two new services that the European Space Agency (ESA) is investigating for future European and Global Mobile Satellite systems. ESA is active in promoting these services in their various mission options including non-geostationary and geostationary satellite systems. A Medium Altitude Global Satellite System (MAGSS) for global personal communications at L and S-band, and a Multiregional Highly inclined Elliptical Orbit (M-HEO) system for multiregional digital audio broadcasting at L-band are described. Both systems are being investigated by ESA in the context of future programs, such as Archimedes, which are intended to demonstrate the new services and to develop the technology for future non-geostationary mobile communication and broadcasting satellites.

  7. Geostationary orbit Earth science platform concepts for global change monitoring

    NASA Technical Reports Server (NTRS)

    Farmer, Jeffery T.; Campbell, Thomas G.; Davis, William T.; Garn, Paul A.; King, Charles B.; Jackson, Cheryl C.

    1991-01-01

    Functionality of a geostationary spacecraft to support Earth science regional process research is identified. Most regional process studies require high spatial and temporal resolution. These high temporal resolutions are on the order of 30 minutes and may be achievable with instruments positioned in a geostationary orbit. A complement of typical existing or near term instruments are identified to take advantage of this altitude. This set of instruments is listed, and the requirements these instruments impose on a spacecraft are discussed. A brief description of the geostationary spacecraft concepts which support these instruments is presented.

  8. Two different attitude control methods for geostationary communication broadcasting satellite

    NASA Astrophysics Data System (ADS)

    Lu, Zhenduo

    1990-02-01

    In this paper, two different attitude control methods for the geostationary satellite - attitude control by satellite-ground loop and autonomous attitude control on board are discussed. Attitude controls of the Chinese satellites STW-1 and STW-2 are described. The design of the attitude control system for three-axis-stabilized spacecraft is also discussed.

  9. 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.

  10. Crew Transfer Options for Servicing of Geostationary Satellites

    NASA Technical Reports Server (NTRS)

    Cerro, Jeffrey A.

    2012-01-01

    In 2011, NASA and DARPA undertook a study to examine capabilities and system architecture options which could be used to provide manned servicing of satellites in Geostationary Earth Orbit (GEO). The study focused on understanding the generic nature of the problem and examining technology requirements, it was not for the purpose of proposing or justifying particular solutions. A portion of this study focused on assessing possible capabilities to efficiently transfer crew between Earth, Low Earth Orbit (LEO), and GEO satellite servicing locations. This report summarizes the crew transfer aspects of manned GEO satellite servicing. Direct placement of crew via capsule vehicles was compared to concepts of operation which divided crew transfer into multiple legs, first between earth and LEO and second between LEO and GEO. In space maneuvering via purely propulsive means was compared to in-space maneuvering which utilized aerobraking maneuvers for return to LEO from GEO. LEO waypoint locations such as equatorial, Kennedy Space Center, and International Space Station inclinations were compared. A discussion of operational concepts is followed by a discussion of appropriate areas for technology development.

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

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

    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.

  12. A Global Cloud Detection Approach for Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Trepte, Q.; Minnis, P.; Palikonda, R.; Ayers, J. K.; Shan, B.; Yost, C. R.

    2014-12-01

    Geostationary satellites provide continuous cloud and meteorological observations over a fixed portion of the Earth's surface, allowing them to monitor and track the development and movement of severe storm systems in real time. For climate studies, geostationary observations provide valuable insight of cloud formation and evolution and how they influence the Earth's radiation budget. Five well-positioned geostationary satellites can cover most of the globe and their products can be merged into a uniform data set. Presently the constellation of these geostationary satellites consists of the NOAA GOES-West (135 W) and East (75 W), the EUMETSAT Meteosat-9 (9.5 E), the Chinese Feng-Yun (105 E), and the Japanese MTSAT-2 (140 E) platforms. Stitching together observations from these imagers requires an understanding of their different spectral characteristics and calibrations. This paper presents the cloud detection algorithms developed using the imager data on the five geostationary satellites. The algorithms are used operationally in NASA's Cloud and Earth's Radiant Energy System (CERES) Time and Space Averaging (TISA) gridded cloud products and for near-real-time retrievals used for weather and nowcasting applications. Examples of cloud mask results for different surface background (ocean, land, desert) and their diurnal changes will be described. Additionally, merged global cloud fractions and zonal cloud distributions are compared with CERES-MODIS, CALIPSO, and NASA LaRC AVHRR cloud fractions. Potential future improvements are discussed.

  13. Apple - Indian experimental geostationary communication satellite

    NASA Astrophysics Data System (ADS)

    Rao, U. R.; Vasagam, R. M.

    Developmental steps, responsibilities, design goals, performance characteristics, and support systems for the ISRO Ariane Passenger Payload Experiment (APPLE) experimental GEO communication satellite are described. The spacecraft underwent structural, thermal, engineering, prototype, and flight qualification tests in India before being shipped to Guyana for launch on the third Ariane test flight. APPLE carries a redundant C-band communication transponder fed by a 900 mm diam parabolic reflector. A 6 GHz uplink and 4 GHz downlink are processed through a diplexer, with the receiver employing a low noise GaAs FET amplifier. In-orbit telemetry is provided by a 4095 MHz beacon with a data rate of 64 bits/sec. Two solar panels supply 210 W of power, while an on-board Ni-Cd storage battery stores 240 Wh for the ascent and during eclipse. Teleconferencing has been successfully performed using the spacecraft link.

  14. 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.

  15. 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 of Ta considered as the temperature of the vegetation cover has been obtained using Tls estimates and a previously found multiple linear regression relationship between Tls and Ta formulated accounting for solar zenith angle and land elevation. A comparison with ground-based collocated Ta observations has given RMS errors of 2.5°C and lower. It can be treated as a proof of the proposed technique's functionality. SEVIRI-derived LAI estimates have been retrieved at LSA SAF from measurements by this sensor in channels 0.6, 0.8, and 1.6 μm under cloud-free conditions at that when using data in the channel 1.6 μm the accuracy of these estimates has increased. In the study the AVHRR- and SEVIRI-derived estimates of daily and monthly precipitation sums for the territory under investigation for the years 2009 - 2013 vegetation seasons have been also used. These estimates have been obtained by the improved integrated Multi Threshold Method (MTM) providing detection and identification of cloud types around the clock throughout the year as well as identification of precipitation zones and determination of instantaneous precipitation maximum intensity within the pixel using the measurement data in different channels of named sensors as predictors. Validation of the MTM has been performed by comparing the daily and monthly precipitation sums with appropriate values resulted from ground-based observations at the meteorological stations of the region. The probability of detecting precipitation zones from satellite data corresponding to the actual ones has been amounted to 70-80%. AVHRR- and SEVIRI-derived daily and monthly precipitation sums have been in reasonable agreement with each other and with results of ground-based observations although they are smoother than the last values. Discrepancies have been noted only for local maxima for which satellite-based estimates of precipitation have been much less than ground-based ones. It may be due to the different spatial scales of areal satellite-derived and point ground-based estimates. To utilize satellite-derived vegetation and meteorological characteristics in the model the special procedures have been developed including: - replacement of ground-based LAI and B estimates used as model parameters by their satellite-derived estimates from AVHRR, MODIS and SEVIRI data. Correctness of such replacement has been confirmed by comparing the time behavior of LAI over the period of vegetation as well as modeled and measured values of evapotranspiration Ev and soil moisture content W; - entering AVHRR-, MODIS- and SEVIRI-derived estimates of Ts.eff Tls, and Ta into the model as input variables instead of ground-measured values with verification of adequacy of model operation under such a change through comparison of the calculated and measured values of W and Ev; - inputing satellite-derived estimates of precipitation during vegetation period retrieved from AVHRR and SEVIRI data using the MTM into the model as input variables. When developing given procedure algorithms and programs have been created to transit from assessment of the rainfall intensity to evaluation of its daily values. The implementation of such a transition requires controlling correctness of the estimates built at each time step. This control includes comparison of areal distributions of three-hour, daily and monthly precipitation amounts obtained from satellite data and calculated by interpolation of standard network observation data; - taking into account spatial heterogeneity of fields of satellite AVHRR-, MODIS- and SEVIRI-derived estimates of LAI, B, LST and precipitation. This has involved the development of algorithms and software for entering the values of all named characteristics into the model in each computational grid node. Values of evapotranspiration E, soil water content W, vertical latent and sensible heat fluxes and other water and heat balance components as well as land surface temperature and moisture area-distributed over the territory of interest have been resulted from the model calculations for the years 2009-2013 vegetation seasons. These calculations have been carried out utilizing satellite-derived estimates of the vegetation characteristics, LST and precipitation. E and W calculation errors have not exceeded the standard values.

  16. 47 CFR 74.643 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Interference to geostationary-satellites. 74.643 Section 74.643 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Television Broadcast Auxiliary Stations ...

  17. 47 CFR 74.643 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Interference to geostationary-satellites. 74.643 Section 74.643 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Television Broadcast Auxiliary Stations ...

  18. 47 CFR 74.643 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Interference to geostationary-satellites. 74.643 Section 74.643 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Television Broadcast Auxiliary Stations ...

  19. 47 CFR 101.145 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Interference to geostationary-satellites. 101.145 Section 101.145 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.145 Interference to...

  20. 47 CFR 101.145 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Interference to geostationary-satellites. 101.145 Section 101.145 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.145 Interference to...

  1. 47 CFR 101.145 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Interference to geostationary-satellites. 101.145 Section 101.145 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.145 Interference to...

  2. 47 CFR 101.145 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Interference to geostationary-satellites. 101.145 Section 101.145 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.145 Interference to...

  3. 47 CFR 101.145 - Interference to geostationary-satellites.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Interference to geostationary-satellites. 101.145 Section 101.145 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.145 Interference to...

  4. Earth-to-Geostationary Orbit Transportation for Space Solar Power System Development

    NASA Technical Reports Server (NTRS)

    Martin, James A.; Donahue, Benjamin B.; Lawrence, Schuyler C.; McClanahan, James A.; Carrington, Connie K. (Technical Monitor)

    2000-01-01

    Space solar power satellites have the potential to provide abundant quantities of electricity for use on Earth. One concept, the Sun Tower, can be assembled in geostationary orbit from pieces transferred from Earth. The cost of transportation is one of the major hurdles to space solar power. This study found that autonomous solar-electric transfer is a good choice for the transportation from LEO to GEO.

  5. Ka-band geostationary satellite spacing requirements and access schemes

    NASA Technical Reports Server (NTRS)

    Caron, Mario; Hindson, Daniel J.

    1995-01-01

    Geostationary satellite systems for wideband personal communications applications have been proposed. This paper looks at the geostationary satellite spacing requirement to meet the ITU-R sharing criterion for FDMA and CDMA access schemes. CDMA capacity equation is first developed. Then the basis for the interference analysis between two systems with an overlapping coverage area is developed for the cases of identical and different access schemes and for bandwidth and power limited systems. An example of an interference analysis between two systems is fully carried out. The paper also points out the inherent problems when comparing systems with different access schemes. It is found that under certain scenarios, CDMA can allow a closer spacing between satellites.

  6. Retrieval and verification of fire radiative power using the Korean geostationary meteorological satellite

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Sun; Lee, Yang-Won

    2014-10-01

    Recently, frequency and strength of global wildfire are on the increase. The wildfire encourages the climate change through release of GHGs into the atmosphere over one time occur. The effect of wildfire GHGs can be estimate by FRP(fire radiative power), many research using the remote sensing are trying for its efficient produce. A satellite fire product including fire mask and FRP was produced by polar orbit satellite at first, thereafter it was expanded to geostationary satellites for continuous monitoring of wide areas. However, geostationary satellites observing in East Asia no got a standard to produce the fire product yet. This paper described a retrieval of FRP using the COMS(Communication, Ocean and Meteorological satellite) that is a Korean geostationary satellite. The COMS FRP was retrieved MIR(Middle infrared) radiance method which approaches by brightness temperature of single waveband. Our test was presented that large scale wildfires(FRP > 300MW and confidence level > 9) occurred in the each April. The COMS FRP showed MAE = 103.67 MW(16%) with the MODIS. This result represents much as possibility of the FRP in East Asia. This paper is expected to provide to baseline for the FRP in East Asia, and apply to biomass loss and estimate the GHGs. In addition, the COMS FRP will contribute to studies of aerosols, economic losses and ecosystem damages as basic data.

  7. Volcanic Ash Retrieval Using a New Geostationary Satellite

    NASA Astrophysics Data System (ADS)

    Lee, K. H.; Lee, K. T.

    2015-06-01

    The paper presents currently developing method of volcanic ash detection and retrieval for the Geostationary Korea Multi-Purpose Satellite (GK-2A). With the launch of GK-2A, aerosol remote sensing including dust, smoke, will begin a new era of geostationary remote sensing. The Advanced Meteorological Imager (AMI) onboard GK-2A will offer capabilities for volcanic ash remote sensing similar to those currently provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite. Based on the physical principles for the current polar and geostationary imagers are modified in the algorithm. Volcanic ash is estimated in detection processing from visible and infrared channel radiances, and the comparison of satellite-observed radiances with those calculated from radiative transfer model. The retrievals are performed operationally every 15 min for volcanic ash for pixel sizes of 2 km. The algorithm currently under development uses a multichannel approach to estimate the effective radius, aerosol optical depth (AOD) simultaneously, both over water and land. The algorithm has been tested with proxy data generated from existing satellite observations and forward radiative transfer simulations. Operational assessment of the algorithm will be made after the launch of GK-2A scheduled in 2018.

  8. The Proposed Ku-Band Non Geostationary Communication Satellite Systems

    NASA Astrophysics Data System (ADS)

    Evans, J. V.

    2000-07-01

    At the 1997 World Radio Conference France was able to secure agreement for Alcatel-Alsthom to launch a non-geostationary satellite system (called SkyBridge) operating at Ku-band, and utilizing the same spectrum as employed by the existing Ku-band geostationary satellites. Provisional power flux density limits for the level of unwanted interference into existing satellite and ground antennas were also adopted and are presently being reviewed by an ITU-R Joint Task Group. SkyBridge subsequently petitioned the U.S. Federal Communications Commission for a license to operate in the United States, causing the FCC to open a window for others to file for such systems. Five new filings were received and this paper describes the six (including Sky-Bridge) designs that have now been proposed. The paper discusses some of the relative merits of the various designs and also the issues of a) interference with the existing geostationary satellites (which may be solvable albeit with the latter losing some capacity) and b) mutual interference among NGSO systems (which may not be solvable in a manner acceptable to their proponents).

  9. Remote sensing of aerosol and radiation from geostationary satellites

    NASA Astrophysics Data System (ADS)

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

    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 similar to those currently provided by the Moderate Resolution Imaging Spectroradiometer MODIS flown on the NASA Earth Observing System EOS satellites The Advanced Baseline Imager ABI on GOES-R will expand NOAA s frequency and coverage of multispectral remote sensing that can support a wide range of weather and environmental applications including the determination of aerosol properties and more accurate determination of surface insolation This paper describes some of the current and planned work at the NOAA Center for Satellite Applications and Research STAR that will use the new capabilities offered by these sensors for aerosol remote sensing and surface insolation as well as work that addresses the transition from past aerosol retrievals to those obtained from the new instruments Among the latter the information content provided by multispectral radiometers is evaluated by analyzing MODIS-derived and operational single-channel aerosol retrievals

  10. Air Quality Science and Regulatory Efforts Require Geostationary Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Pickering, Kenneth E.; Allen, D. J.; Stehr, J. W.

    2006-01-01

    Air quality scientists and regulatory agencies would benefit from the high spatial and temporal resolution trace gas and aerosol data that could be provided by instruments on a geostationary platform. More detailed time-resolved data from a geostationary platform could be used in tracking regional transport and in evaluating mesoscale air quality model performance in terms of photochemical evolution throughout the day. The diurnal cycle of photochemical pollutants is currently missing from the data provided by the current generation of atmospheric chemistry satellites which provide only one measurement per day. Often peak surface ozone mixing ratios are reached much earlier in the day during major regional pollution episodes than during local episodes due to downward mixing of ozone that had been transported above the boundary layer overnight. The regional air quality models often do not simulate this downward mixing well enough and underestimate surface ozone in regional episodes. Having high time-resolution geostationary data will make it possible to determine the magnitude of this lower-and mid-tropospheric transport that contributes to peak eight-hour average ozone and 24-hour average PM2.5 concentrations. We will show ozone and PM(sub 2.5) episodes from the CMAQ model and suggest ways in which geostationary satellite data would improve air quality forecasting. Current regulatory modeling is typically being performed at 12 km horizontal resolution. State and regional air quality regulators in regions with complex topography and/or land-sea breezes are anxious to move to 4-km or finer resolution simulations. Geostationary data at these or finer resolutions will be useful in evaluating such models.

  11. 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.

  12. 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.

  13. 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 (75W) and GOES-W (135W). These are being merged with like products from EUMETSAT based on METEOSAT (0 and 63E) and from JMA based on the Geostationary Meteorological Satellite System (140E). In the near future, NOAA's Climate Data Record Program will provide the albedo product over the entire GOES period of record (1978-present).

  14. Fuzzy logic techniques for rendezvous and docking of two geostationary satellites

    NASA Technical Reports Server (NTRS)

    Ortega, Guillermo

    1995-01-01

    Large assemblings in space require the ability to manage rendezvous and docking operations. In future these techniques will be required for the gradual build up of big telecommunication platforms in the geostationary orbit. The paper discusses the use of fuzzy logic to model and implement a control system for the docking/berthing of two satellites in geostationary orbit. The system mounted in a chaser vehicle determines the actual state of both satellites and generates torques to execute maneuvers to establish the structural latching. The paper describes the proximity operations to collocate the two satellites in the same orbital window, the fuzzy guidance and navigation of the chaser approaching the target and the final Fuzzy berthing. The fuzzy logic system represents a knowledge based controller that realizes the close loop operations autonomously replacing the conventional control algorithms. The goal is to produce smooth control actions in the proximity of the target and during the docking to avoid disturbance torques in the final assembly orbit. The knowledge of the fuzzy controller consists of a data base of rules and the definitions of the fuzzy sets. The knowledge of an experienced spacecraft controller is captured into a set of rules forming the Rules Data Base.

  15. Orbit analysis of a geostationary gravitational wave interferometer detector array

    NASA Astrophysics Data System (ADS)

    Tinto, Massimo; de Araujo, Jose C. N.; Kuga, Helio K.; Alves, Márcio E. S.; Aguiar, Odylio D.

    2015-09-01

    We analyze the trajectories of three geostationary satellites forming the geostationary gravitational wave interferometer (GEOGRAWI) [1], a space-based laser interferometer mission aiming to detect and study gravitational radiation in the (10-4-10) Hz band. The combined effects of the gravity fields of the Earth, the Sun and the Moon make the three satellites deviate from their nominally stationary, equatorial and equilateral configuration. Since changes in the satellites’s relative distances and orientations could negatively affect the precision of the laser heterodyne measurements, we have derived the time-dependence of the inter-satellite distances and velocities, the variations of the polar angles made by the constellation’s three arms with respect to a chosen reference frame and the time changes of the triangle’s enclosed angles. We find that during the time between two consecutive station-keeping maneuvers (about two weeks) the relative variations of the inter-satellite distances do not exceed a value of 0.05%, while the relative velocities between pairs of satellites remain smaller than about 0.7 m s-1. In addition, we find the angles made by the arms of the triangle with the equatorial plane to be periodic functions of time whose amplitudes grow linearly with time; the maximum variations experienced by these angles as well as by those within the triangle remain smaller than 3 arc-minutes, while the east-west angular variations of the three arms remain smaller than about 15 arc-minutes during the two-week period.

  16. Satellite orbit computation methods

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Mathematical and algorithmical techniques for solution of problems in satellite dynamics were developed, along with solutions to satellite orbit motion. Dynamical analysis of shuttle on-orbit operations were conducted. Computer software routines for use in shuttle mission planning were developed and analyzed, while mathematical models of atmospheric density were formulated.

  17. 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 heat balance components by entering the spatially-distributed NOAA-, EOS/Terra and Aqua-, Meteosat-9-derived estimates of LAI, B, Tls and Ta as well as the spatially-interpolated ground-based meteorological inputs (precipitation intensity, air temperature and humidity) into the model. - calculation of evapotranspiration, soil water and heat content and other water and heat balance components for the study area of the CCR for years 2009-2012 vegetation seasons utilizing the spatial fields of the AVHRR- and MODIS-derived values of LAI and B as well as the AVHRR-, MODIS-and SEVIRI-derived values of Tls and Ta; presentation of the results as area-distributions over the whole territory under consideration. The present study was carried out with support of the Russian Foundation of Basic Researches - grant N 13-05-00559.

  18. Fotometrical Ovservations Geostationary Satellites on Small Phase Angles, on Russian

    NASA Astrophysics Data System (ADS)

    Sukhov, P., P.

    2013-11-01

    For determination photometrical and dynamic features geostationary satellites required for his identifications as a rule, need long (the half of the year - year) photometrical observations under different positions GSS for observer. The author proposes to carry out photometry GSS times when equatorial satellites (with zero inclination and zero eccentricity) have a small phase angles. That is writing the light curves when GSS entering and output from Earth's shadow near dates equinox, when brightness satellite increases on several magnitude. In this, case pos-sible effectively to use the telescopes with diameter of the mirror 50-70 cm. You can also get much more information about the object than on the long-term observation of large phase angles.

  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. Research on space-based optical surveillance's observation strategy of geostationary-orbit's pitch point region

    NASA Astrophysics Data System (ADS)

    Wang, Xue-ying; An, Wei; Wu, Yu-hao; Li, Jun

    2015-03-01

    In order to surveillance the geostationary (GEO) objects, including man-made satellites and space debris, more efficiently, a space-based optical surveillance system was designed in this paper. A strategy to observe the pinch point region was selected because of the GEO objects' dynamics features. That strategy affects the surveillance satellites orbital type and sensor pointing strategy. In order to minimize total surveillance satellites and the revisit time for GEO objects, a equation was set. More than 700 GEO objects' TLE from NASA's website are used for simulation. Results indicate that the revisit time of the surveillance system designed in this paper is less than 24 hours, more than 95% GEO objects can be observed by the designed system.

  1. Surface solar radiation from geostationary satellites for renewable energy

    NASA Astrophysics Data System (ADS)

    Laszlo, Istvan; Liu, Hongqing; Heidinger, Andrew; Goldberg, Mitchell

    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 heritage meteorological products (cloud and aerosol properties, precipitation, winds, etc.), but some will be for interdisciplinary use, such as for the solar energy industry. The planned rapid observations (5-15 minutes) from ABI provide an opportunity to obtain information needed for solar energy applications where frequent observations of solar radiation reaching the surface are essential for planning and load management. In this paper we describe a physical, radiative-transfer-based algorithm for the retrieval of surface solar irradiance that uses atmospheric and surface parameters derived independently from multispectral ABI radiances. The algorithm is designed to provide basic radiation budget products (total solar irradiance at the surface), as well as products specifically needed for the solar energy industry (average, midday and clear-sky insolation, clear-sky days, diffuse and direct normal radiation, etc.). Two alternative algorithms, which require less ABI atmosphere and surface products or no explicit knowledge of the surface albedo, are also explored along with their limitations. The accuracy of surface solar radiation retrievals are assessed using long-term MODIS and GOES satellite data and surface measurements at the Surface Radiation (SURFRAD) network.

  2. 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 imagerSEVERI. 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.

  3. Investigation of water vapor motion winds from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Velden, Christopher

    1993-01-01

    Motions deduced in animated water vapor imagery from geostationary satellites can be used to infer wind fields in cloudless regimes. For the past several years, CIMSS has been exploring this potentially important source of global-scale wind information. Recently, METEOSAT-3 data has become routinely available to both the U.S. operational and research community. Compared with the current GOES satellite, the METEOSAT has a superior resolution (5 km vs. 16 km) in its water vapor channel. Preliminary work: at CIMSS has demonstrated that wind sets derived from METEOSAT water vapor imagery can provide important upper-tropospheric wind information in data void areas, and can positively impact numerical model guidance in meteorological applications. Specifically, hurricane track forecasts can be improved. Currently, we are exploring methods to further improve the derivation and quality of the water vapor wind sets.

  4. Geomagnetic pulsations observed simultaneously on three geostationary satellites

    NASA Technical Reports Server (NTRS)

    Hughes, W. J.; Mcpherron, R. L.; Barfield, J. N.

    1978-01-01

    Simultaneous observations of magnetic pulsations have been made by three geostationary satellites carrying similar magnetometers and acting as an azimuthal array. Autospectral and cross-spectral analysis yields coherence and phase differences between the pulsations at the satellite positions. The majority of the data fit the Kelvin-Helmholtz generation mechanism. The azimuthal wave number changes sign near noon and corresponds to propagation away from noon. Usually, the wave number is less than 10 deg per degree of longitude. Later in the afternoon, however, strong pulsations are observed with low coherence, implying large wave numbers. This suggests an instability driven by a gradient in the intensity of energetic protons, which may be expected at this local time. The data also suggest that some of the observed phase difference between the azimuthal components is due to small separations in magnetic shell, whereas this is not the case for the radial components. This implies a localized field-line resonance.

  5. Remote sensing of aerosol and radiation from geostationary satellites

    NASA Astrophysics Data System (ADS)

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

    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 comparison of satellite-observed reflectances derived from a single visible channel with those calculated from detailed radiative transfer. The radiative transfer calculation accounts for multiple scattering by molecules, aerosol and cloud and absorption by the major atmospheric gases. The retrievals are performed operationally every 30 min for aerosol and every hour for radiation for pixel sizes of 4-km (aerosol) and 15- to 50-km (radiation). Both retrievals estimate the surface reflectance as a byproduct from the time composite of clear visible reflectances assuming fixed values of the aerosol optical depth. With the launch of GOES-R NOAA will begin a new era of geostationary remote sensing. The Advanced Baseline Imager (ABI) onboard GOES-R will offer capabilities for aerosol remote sensing similar to those currently provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) flown on the NASA Earth Observing System (EOS) satellites. The ABI aerosol algorithm currently under development uses a multi-channel approach to estimate the aerosol optical depth and aerosol model simultaneously, both over water and land. Its design is strongly inspired by the MODIS aerosol algorithm. The ABI shortwave radiation budget algorithm is based on the successful GOES Surface and Insolation Product system of NOAA and the NASA Clouds and the Earth’s Radiant Energy System (CERES), Surface and Atmospheric Radiation Budget (SARB) algorithm. In all phases of the development, the algorithms are tested with proxy data generated from existing satellite observations and forward simulations. Final assessment of the performance will be made after the launch of GOES-R scheduled in 2012.

  6. A TEMPORAL MAP IN GEOSTATIONARY ORBIT: THE COVER ETCHING ON THE EchoStar XVI ARTIFACT

    SciTech Connect

    Weisberg, Joel M.; Paglen, Trevor

    2012-10-01

    Geostationary satellites are unique among orbital spacecraft in that they experience no appreciable atmospheric drag. After concluding their respective missions, geostationary spacecraft remain in orbit virtually in perpetuity. As such, they represent some of human civilization's longest lasting artifacts. With this in mind, the EchoStar XVI satellite, to be launched in fall 2012, will play host to a time capsule intended as a message for the deep future. Inspired in part by the Pioneer Plaque and Voyager Golden Records, the EchoStar XVI Artifact is a pair of gold-plated aluminum jackets housing a small silicon disk containing 100 photographs. The Cover Etching, the subject of this paper, is etched onto one of the two jackets. It is a temporal map consisting of a star chart, pulsar timings, and other information describing the epoch from which EchoStar XVI came. The pulsar sample consists of 13 rapidly rotating objects, 5 of which are especially stable, having spin periods <10 ms and extremely small spin-down rates. In this paper, we discuss our approach to the time map etched onto the cover and the scientific data shown on it, and we speculate on the uses that future scientists may have for its data. The other portions of the EchoStar XVI Artifact will be discussed elsewhere.

  7. Monitoring Snow Using Geostationary Satellite Retrievals During the SAAWSO Project

    NASA Astrophysics Data System (ADS)

    Rabin, Robert M.; Gultepe, Ismail; Kuligowski, Robert J.; Heidinger, Andrew K.

    2015-12-01

    The SAAWSO (Satellite Applications for Arctic Weather and SAR (Search And Rescue) Operations) field programs were conducted by Environment Canada near St. Johns, NL and Goose Bay, NL in the winters of 2012-13 and 2013-14, respectively. The goals of these programs were to validate satellite-based nowcasting products, including snow amount, wind intensity, and cloud physical parameters (e.g., cloud cover), over northern latitudes with potential applications to Search And Rescue (SAR) operations. Ground-based in situ sensors and remote sensing platforms were used to measure microphysical properties of precipitation, clouds and fog, radiation, temperature, moisture and wind profiles. Multi-spectral infrared observations obtained from Geostationary Operational Environmental Satellite (GOES)-13 provided estimates of cloud top temperature and height, phase (water, ice), hydrometer size, extinction, optical depth, and horizontal wind patterns at 15 min intervals. In this work, a technique developed for identifying clouds capable of producing high snowfall rates and incorporating wind information from the satellite observations is described. The cloud top physical properties retrieved from operational satellite observations are validated using measurements obtained from the ground-based in situ and remote sensing platforms collected during two precipitation events: a blizzard heavy snow storm case and a moderate snow event. The retrieved snow precipitation rates are found to be comparable to those of ground-based platform measurements in the heavy snow event.

  8. Satellite orbit determination

    NASA Technical Reports Server (NTRS)

    Jordan, J. F.; Boggs, D. H.; Born, G. H.; Christensen, E. J.; Ferrari, A. J.; Green, D. W.; Hylkema, R. K.; Mohan, S. N.; Reinbold, S. J.; Sievers, G. L.

    1973-01-01

    A historic account of the activities of the Satellite OD Group during the MM'71 mission is given along with an assessment of the accuracy of the determined orbit of the Mariner 9 spacecraft. Preflight study results are reviewed, and the major error sources described. Tracking and data fitting strategy actually used in the real time operations is itemized, and Deep Space Network data available for orbit fitting during the mission and the auxiliary information used by the navigation team are described. A detailed orbit fitting history of the first four revolutions of the satellite orbit of Mariner 9 is presented, with emphasis on the convergence problems and the delivered solution for the first orbit trim maneuver. Also included are a solution accuracy summary, the history of the spacecraft orbit osculating elements, the results of verifying the radio solutions with TV imaging data, and a summary of the normal points generated for the relativity experiment.

  9. The provision of spectrum for feeder links of non-geostationary mobile satellites

    NASA Technical Reports Server (NTRS)

    Bowen, Robert R.

    1993-01-01

    The possibility of sharing spectrum in the 30/20 GHz band between geostationary fixed-satellite systems and feeder-links of low-earth orbit (LEO) mobile-satellite systems is addressed, taking into account that International Telecommunications Union (ITU) Radio Regulation 2613 would be a factor in such sharing. Interference into each network in both the uplink at 30 GHz and the downlink at 20 GHz is considered. It is determined that if sharing were to take place the mobile-satellite may have to cease transmission often for intervals up to 10 seconds, may have to use high-gain tracking antennas on its spacecraft, and may find it an advantage to use code-division multiple access. An alternate solution suggested is to designate a band 50 to 100 MHz wide at 28 and 18 GHz to be used primarily for feeder links to LEO systems.

  10. Spacecraft flight control system design selection process for a geostationary communication satellite

    NASA Technical Reports Server (NTRS)

    Barret, C.

    1992-01-01

    The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Now, as we launch the Mars observer and the Cassini spacecraft, stability and control have become higher priorities. The flight control system design selection process is reviewed using as an example a geostationary communication satellite which is to have a life expectancy of 10 to 14 years. Disturbance torques including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques are assessed to quantify the disturbance environment so that the required compensating torque can be determined. Then control torque options, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, nutation dampers, inertia augmentation techniques, three-axis control, reactions control system (RCS), and RCS sizing, are considered. A flight control system design is then selected and preliminary stability criteria are met by the control gains selection.

  11. 47 CFR 25.142 - Licensing provisions for the non-voice, non-geostationary mobile-satellite service.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-geostationary mobile-satellite service. 25.142 Section 25.142 Telecommunication FEDERAL COMMUNICATIONS... Stations § 25.142 Licensing provisions for the non-voice, non-geostationary mobile-satellite service. (a... the non-voice, non-geostationary mobile-satellite service shall describe in detail the proposed...

  12. 47 CFR 25.142 - Licensing provisions for the non-voice, non-geostationary mobile-satellite service.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-geostationary mobile-satellite service. 25.142 Section 25.142 Telecommunication FEDERAL COMMUNICATIONS... Stations § 25.142 Licensing provisions for the non-voice, non-geostationary mobile-satellite service. (a... the non-voice, non-geostationary mobile-satellite service shall describe in detail the proposed...

  13. Diurnal and seasonal variations of clouds from geostationary satellite data

    NASA Technical Reports Server (NTRS)

    Minnis, P.; Harrison, E. F.

    1983-01-01

    Hourly 8-km visible (0.55-0.75 micron) and infrared (10.5-12.5 microns) data from the eastern Geostationary Operational Environmental Satellite were analyzed with a hybrid bispectral threshold method to yield total, low, middle, and high level cloud fractions and cloud radiative parameters for 250 x 250 sq km regions. These data were analyzed for the area between 45 deg N and 45 deg S, and longitudes 30 deg W and 125 deg W for the autumn of 1978 and the winter of 1979. Preliminary results for winter are presented in the present study. It is shown that diurnal variations of clouds may reveal diurnal variability in regional and large-scale circulation patterns. These diurnal cloud cycles may also have substantial effects on regional and large-scale radiation budgets and, therefore, influence circulation patterns at various spatial scales.

  14. 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.

  15. Space-based sensor management and geostationary satellites tracking

    NASA Astrophysics Data System (ADS)

    El-Fallah, A.; Zatezalo, A.; Mahler, R.; Mehra, R. K.; Donatelli, D.

    2007-04-01

    Sensor management for space situational awareness presents a daunting theoretical and practical challenge as it requires the use of multiple types of sensors on a variety of platforms to ensure that the space environment is continuously monitored. We demonstrate a new approach utilizing the Posterior Expected Number of Targets (PENT) as the sensor management objective function, an observation model for a space-based EO/IR sensor platform, and a Probability Hypothesis Density Particle Filter (PHD-PF) tracker. Simulation and results using actual Geostationary Satellites are presented. We also demonstrate enhanced performance by applying the ProgressiveWeighting Correction (PWC) method for regularization in the implementation of the PHD-PF tracker.

  16. 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.

  17. Potential for calibration of geostationary meteorological satellite imagers using the Moon

    USGS Publications Warehouse

    Stone, T.C.; Kieffer, H.H.; Grant, I.F.

    2005-01-01

    Solar-band imagery from geostationary meteorological satellites has been utilized in a number of important applications in Earth Science that require radiometric calibration. Because these satellite systems typically lack on-board calibrators, various techniques have been employed to establish "ground truth", including observations of stable ground sites and oceans, and cross-calibrating with coincident observations made by instruments with on-board calibration systems. The Moon appears regularly in the margins and corners of full-disk operational images of the Earth acquired by meteorological instruments with a rectangular field of regard, typically several times each month, which provides an excellent opportunity for radiometric calibration. The USGS RObotic Lunar Observatory (ROLO) project has developed the capability for on-orbit calibration using the Moon via a model for lunar spectral irradiance that accommodates the geometries of illumination and viewing by a spacecraft. The ROLO model has been used to determine on-orbit response characteristics for several NASA EOS instruments in low Earth orbit. Relative response trending with precision approaching 0.1% per year has been achieved for SeaWiFS as a result of the long time-series of lunar observations collected by that instrument. The method has a demonstrated capability for cross-calibration of different instruments that have viewed the Moon. The Moon appears skewed in high-resolution meteorological images, primarily due to satellite orbital motion during acquisition; however, the geometric correction for this is straightforward. By integrating the lunar disk image to an equivalent irradiance, and using knowledge of the sensor's spectral response, a calibration can be developed through comparison against the ROLO lunar model. The inherent stability of the lunar surface means that lunar calibration can be applied to observations made at any time, including retroactively. Archived geostationary imager data that contains the Moon can be used to develop response histories for these instruments, regardless of their current operational status.

  18. Categorizing precipitating clouds by using radar and geostationary satellite

    NASA Astrophysics Data System (ADS)

    Wetchayont, P.; Hayasaka, T.; Katagiri, S.; Satomura, T.

    2012-11-01

    The classification of precipitating cloud systems over Thailand was attempted by using radar reflectivity and Multifunctional Transport Satellites (MTSAT) infrared brightness temperature (TBB) data. The proposed method can classify the convective rain (CR) area, stratiform rain (SR) area and non-precipitation area such as cumulus and cirrus cloud by applying an integrating analysis of rain gauge, ground-based radar and geostationary satellite data. Since the present study focuses on precipitation, the classified results of precipitation area are used to estimate quantitative precipitation amount. To merge different rainfall products, the bias between the products should be removed. The bias correction method is used to estimate spatially varying multiplicative biases in hourly radar and satellite rainfall using a gauge and radar rainfall product, respectively. An extreme rain event was selected to obtain the multiplicative bias correction and to merge data set. Correlation coefficient (CC), root mean square error (RMSE) and mean bias are used to evaluate the performance of bias correction method. The combined radar-MTSAT method is a simple and useful method. This method has been successfully applied to merge radar and gauge rainfall for hydrological purpose.

  19. 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.

  20. Plans for EUMETSAT's Thrid Generation Meteosat (MTG) geostationary satellite program

    NASA Astrophysics Data System (ADS)

    Stuhlmann, R. S.; Tjemkes, S. A. T.; Rodriguez, A. R. R.; Bzy, J. L. B.; Aminou, D. A.; Bensi, P. B.

    After movement of the first Meteosat Second Generation (MSG) satellite to 3.4 degree West by end of January 2004, the satellite has been renamed Meteosat-8 and the system has been declared fully operational. Meteosat-8 is now the primary European source of geostationary observations over Europe and Africa, as the first in a series of four satellites expected to deliver operational services at least until 2015. Considering the time required for the definition phases of new space systems their typical development cycle and the approval of complex programmes, it is necessary to plan for follow-up missions. EUMETSAT has therefore, as a first step in the preparation of the Third Generation Meteosat (MTG) European geostationary satellite system, established a USER Consultation Process aimed at capturing the foreseeable high-level user/service needs and priorities of the EUMETSAT customers and users in the 2015-2025 timeframe. This process was implemented through the set up of Applications Expert Groups (AEGs) tasked to propose their vision on operational services, to define associated needs and priorities for input information and observations. At the 1st Post-MSG User Consultation Workshop, November 2001, the work of the AEGs were presented to a broader user group serving as a basis for the identification of relevant observing techniques and the definition of requirements for the MTG observation missions. Currently, a total of five observation missions has been defined for pre-phase A studies at system level under ESA contract to be started in July 2004. Those are: High Resolution Fast Imagery Mission (successor to MSG SEVIRI HRV mission) Full Disk High Spectral Resolution Imagery Mission (successor to the mission of other SEVIRI channels) Lightning Imagery Mission IR Sounding Mission UV Sounding Mission Prior to the start of industry pre-phase A studies the joined ESA/EUMETSAT MTG Project Team, supported by an external group of experts named the MTG Mission Team, established the MTG Mission requirements document (MRD), to be released by 1st April. The presentation will give an overview on the current status of definition of the five observation missions, followed by a brief description of the MTG schedule and related milestones.

  1. 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

  2. Using Satellite Measurements to Investigate Regional-scale Chemistry: The Case for Geostationary Observations

    NASA Technical Reports Server (NTRS)

    Fishman, Jack; Wozniak, Amy; Creilson, Jack

    2007-01-01

    One of the recommendations of the Decadal Survey that was recently released by the National Academy of Science was that of a geostationary platform from which to obtain trace gas measurements. The use of such a platform is particularly advantageous when applied to understanding the formation of regional air pollution. This study demonstrates the challenges of trying to utilize information from instruments on satellites in low-earth orbit (LEO). We also demonstrate the advantage gained through a simulation that would provide hourly observations. In this case study, we take advantage of the high resolution Level-2 orbital data available from the Ozone Monitoring Instrument (OMI), in conjunction with assimilated stratospheric column ozone fields, to evaluate if meaningful tropospheric ozone information can be obtained on a regional scale. We focus on a period on late June 2005 when a widespread pollution episode enveloped the Houston metropolitan area as well as a large region in southeast Texas.

  3. Orbit and clock analysis of Compass GEO and IGSO satellites

    NASA Astrophysics Data System (ADS)

    Steigenberger, P.; Hugentobler, U.; Hauschild, A.; Montenbruck, O.

    2013-06-01

    China is currently focussing on the establishment of its own global navigation satellite system called Compass or BeiDou. At present, the Compass constellation provides four usable satellites in geostationary Earth orbit (GEO) and five satellites in inclined geosynchronous orbit (IGSO). Based on a network of six Compass-capable receivers, orbit and clock parameters of these satellites were determined. The orbit consistency is on the 1-2 dm level for the IGSO satellites and on the several decimeter level for the GEO satellites. These values could be confirmed by an independent validation with satellite laser ranging. All Compass clocks show a similar performance but have a slightly lower stability compared to Galileo and the latest generation of GPS satellites. A Compass-only precise point positioning based on the products derived from the six-receiver network provides an accuracy of several centimeters compared to the GPS-only results.

  4. Probabilistic estimation of precipitation combining geostationary and TRMM satellite data

    NASA Astrophysics Data System (ADS)

    de Marchi, Carlo

    Environmental satellites represent an economic and easily accessible monitoring means for a plethora of environmental variables, the most important of which is arguably precipitation. While precipitation can also be measured by conventional rain gages and radar, in most world regions, satellites provide the only reliable and sustainable monitoring system. This thesis presents a methodology for estimating precipitation using information from the satellite-borne precipitation radar of the Tropical Rainfall Measurement Mission (TRMM). The methodology combines the precise, but infrequent, TRMM data with the infrared (IR) and visible (VIS) images continuously produced by geostationary satellites to provide precipitation estimates at a variety of temporal and spatial scales. The method is based on detecting IR patterns associated with convective storms and characterizing their evolution phases. Precipitation rates are then estimated for each phase based on IR, VIS, and terrain information. This approach improves the integration of TRMM precipitation rates and IR/VIS data by differentiating major storms from smaller events and noise, and by separating the distinct precipitation regimes associated with each storm phase. Further, the methodology explicitly quantifies the uncertainty of the precipitation estimates by computing their full probability distributions instead of just single "optimal" values. Temporal and spatial autocorrelation of precipitation are fully accounted for by using spatially optimal estimator methods (kriging), allowing to correctly assess precipitation uncertainty over different spatial and temporal scales. This approach is tested in the Lake Victoria basin over the period 1996-1998 against precipitation data from more than one hundred rain gages representing a variety of precipitation regimes. The precipitation estimates were shown to exhibit much lower bias and better correlation with ground data than commonly used methods. Furthermore, the approach reliably reproduced the variability of precipitation over a range of temporal and spatial scales.

  5. 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.

  6. Investigation of water vapor motion winds from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Velden, Christopher S.; Nieman, Steven J.; Wanzong, Steven

    1994-01-01

    Water vapor imagery from geostationary satellites has been available for over a decade. These data are used extensively by operational analysts and forecasters, mainly in a qualitative mode (Weldon and Holmes 1991). In addition to qualitative applications, motions deduced in animated water vapor imagery can be used to infer wind fields in cloudless regimes, thereby augmenting the information provided by cloud-drift wind vectors. Early attempts at quantifying the data by tracking features in water vapor imagery met with modest success (Stewart et al. 1985; Hayden and Stewart 1987). More recently, automated techniques have been developed and refined, and have resulted in upper-level wind observations comparable in quality to current operational cloud-tracked winds (Laurent 1993). In a recent study by Velden et al. (1993) it was demonstrated that wind sets derived from Meteosat-3 (M-3) water vapor imagery can provide important environmental wind information in data void areas surrounding tropical cyclones, and can positively impact objective track forecasts. M-3 was repositioned to 75W by the European Space Agency in 1992 in order to provide complete coverage of the Atlantic Ocean. Data from this satellite are being transmitted to the U.S. for operational use. Compared with the current GOES-7 (G-7) satellite (positioned near 112W), the M-3 water vapor channel contains a superior horizontal resolution (5 km vs. 16 km ). In this paper, we examine wind sets derived using automated procedures from both GOES-7 and Meteosat-3 full disk water vapor imagery in order to assess this data as a potentially important source of large-scale wind information. As part of a product demonstration wind sets were produced twice a day at CIMSS during a six-week period in March and April (1994). These data sets are assessed in terms of geographic coverage, statistical accuracy, and meteorological impact through preliminary results of numerical model forecast studies.

  7. Developing Geostationary Satellite Imaging at the Navy Precision Optical Interferometer

    NASA Astrophysics Data System (ADS)

    van Belle, G.; von Braun, K.; Armstrong, J. T.; Baines, E. K.; Schmitt, H. R.; Jorgensen, A. M.; Elias, N.; Mozurkewich, D.; Oppenheimer, R.; Restaino, S.

    The Navy Precision Optical Interferometer (NPOI) is a six-beam long-baseline optical interferometer, located in Flagstaff, Arizona; the facility is operated by a partnership between Lowell Observatory, the US Naval Observatory, and the Naval Research Laboratory. NPOI operates every night of the year (except holidays) in the visible with baselines between 8 and 100 meters (up to 432m is available), conducting programs of astronomical research and technology development for the partners. NPOI is the only such facility as yet to directly observe geostationary satellites, enabling milliarcsecond resolution of these objects. To enhance this capability towards true imaging of geosats, a program of facility upgrades will be outlined. These upgrades include AO-assisted large apertures feeding each beam line, new visible and near-infrared instrumentation on the back end, and infrastructure supporting baseline-wavelength bootstrapping which takes advantage of the spectral and morphological features of geosats. The large apertures will enable year-round observations of objects brighter than 10th magnitude in the near-IR. At its core, the system is enabled by a approach that tracks the low-resolution (and thus, high signal-to-noise), bright near-IR fringes between aperture pairs, allowing multi-aperture phasing for high-resolution visible light imaging. A complementary program of visible speckle and aperture masked imaging at Lowell's 4.3-m Discovery Channel Telescope, for constraining the low-spatial frequency imaging information, will also be outlined, including results from a pilot imaging study.

  8. Fixed satellite service frequency allocations and orbit assignment procedures for commercial satellite systems

    NASA Astrophysics Data System (ADS)

    Tycz, Thomas S.

    1990-07-01

    The international regulatory framework which resulted from the 1988 International Telecommunication Union (ITU) Conference on Space Services (ORB-88) and its potential effect on the implementation of US satellite systems are discussed. The impact of several significant results of ORB-88 on the ability of the FCC to assign geostationary satellite orbital positions within the US and to secure international protection for these assignments is reviewed. A table of fixed satellite service frequency allocations in North, Central, and South America is given.

  9. Investigating the Use of Deep Convective Clouds (DCCT) to Monitor On-orbit Performance of the Geostationary Lightning Mapper (GLM) using Lightning Imaging Sensor (LIS) Measurements

    NASA Technical Reports Server (NTRS)

    Buechler, Dennis E.; Christian, Hugh J.; Koshak, William J.; Goodman, Steven J.

    2013-01-01

    There is a need to monitor the on-orbit performance of the Geostationary Lightning Mapper (GLM) on the Geostationary Operational Environmental Satellite R (GOES-R) for changes in instrument calibration that will affect GLM's lightning detection efficiency. GLM has no onboard calibration so GLM background radiance observations (available every 2.5 min) of Deep Convective Clouds (DCCs) are investigated as invariant targets to monitor GLM performance. Observations from the Lightning Imaging Sensor (LIS) and the Visible and Infrared Scanner (VIRS) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite are used as proxy datasets for GLM and ABI 11 m measurements.

  10. Low Earth Orbit satellite/terrestrial mobile service compatibility

    NASA Technical Reports Server (NTRS)

    Sheriff, Ray E.; Gardiner, John G.

    1993-01-01

    Currently the geostationary type of satellite is the only one used to provide commercial mobile-satellite communication services. Low earth orbit (LEO) satellite systems are now being proposed as a future alternative. By the implementation of LEO satellite systems, predicted at between 5 and 8 years time, mobile space/terrestrial technology will have progressed to the third generation stage of development. This paper considers the system issues that will need to be addressed when developing a dual mode terminal, enabling access to both terrestrial and LEO satellite systems.

  11. The current legal regime of the geostationary orbit and prospects for the future

    NASA Astrophysics Data System (ADS)

    Jasentuliyana, N.; Chipman, R.

    The legal status of the geostationary orbit is defined by the 1967 UN Outer Space Treaty, which provides that space is "free for use by all countries", and the ITU Convention and Radio Regulations, which give priority to existing satellite systems, thus arguably limiting the right of other countries to access. Thus arises a conflict between space powers, which favour pragmatic technical co-ordination through the ITU, and developing countries, which look to the United Nations for general political and legal principles based on the equality of all States. A process of compromise is underway in the ITU WARC-ORB conference. While the results of the 1985 session were encouraging, ongoing negotiations will be necessary, with compromises involving both general legal principles and pragmatic mechanisms for co-ordinating existing satellites. While the ITU will be the main negotiating forum, the UN can incorporate general principles into international space law. An Appendix contains the main provisions of international law relating to the orbit.

  12. Field line distribution of mass density at geostationary orbit

    NASA Astrophysics Data System (ADS)

    Denton, R. E.; Takahashi, Kazue; Lee, Jimyoung; Zeitler, C. K.; Wimer, N. T.; Litscher, L. E.; Singer, H. J.; Min, Kyungguk

    2015-06-01

    The distribution of mass density along the field lines affects the ratios of toroidal (azimuthally oscillating) Alfvn frequencies, and given the ratios of these frequencies, we can get information about that distribution. Here we assume the commonly used power law form for the field line distribution, ?m = ?m,eq(LRE/R)?, where ?m,eq is the value of the mass density ?m at the magnetic equator, L is the L shell, RE is the Earth's radius, R is the geocentric distance to a point on the field line, and ? is the power law coefficient. Positive values of ? indicate that ?m increases away from the magnetic equator, zero value indicates that ?m is constant along the magnetic field line, and negative ? indicates that there is a local peak in ?m at the magnetic equator. Using 12 years of observations of toroidal Alfvn frequencies by the Geostationary Operational Environmental Satellites, we study the typical dependence of inferred values of ? on the magnetic local time (MLT), the phase of the solar cycle as specified by the F10.7 extreme ultraviolet solar flux, and geomagnetic activity as specified by the auroral electrojet (AE) index. Over the mostly dayside range of the observations, we find that ? decreases with respect to increasing MLT and F10.7, but increases with respect to increasing AE. We develop a formula that depends on all three parameters, ?3Dmodel=2.2+1.3cos(MLT15)+0.0026AEcos((MLT-0.8)15)+2.110-5AEF10.7-0.010F10.7, that models the binned values of ? within a standard deviation of 0.3. While we do not yet have a complete theoretical understanding of why ? should depend on these parameters in such a way, we do make some observations and speculations about the causes. At least part of the dependence is related to that of ?m,eq; higher ?, corresponding to steeper variation with respect to magnetic latitude, occurs when ?m,eq is lower.

  13. An LO Phase Link Using a Commercial Geo-Stationary Satellite

    NASA Technical Reports Server (NTRS)

    Bardin, Joseph C.; Weinreb, Sander; Bagri, Durgadas S.

    2005-01-01

    This viewgraph presentation reviews an experiment to determine feasibility of achieving 1 ps level time transfer using a satellite link and make use of inexpensive Ku band transmit/receive equipment. It reviews the advantages of Two Way Satellite Time Transfer using a commercial Geo-Stationary Satellite: (1) Commercial satellites are available (2) Significant cost reduction when compared to Hydrogen Masers and (3) Large footprint- entire US (including Hawaii) with just one satellite.

  14. Geostationary Operational Environmental Satellite (GOES I-M) METSAT project

    NASA Technical Reports Server (NTRS)

    Blaney, K.; Thienel, C.

    1991-01-01

    The primary objective of the METSAT project is to provide a satellite system that meets the National Environmental Satellite Data and Information Service (NESDIS) requirements as specified by NOAA. For the GOES I-M spacecraft, these requirements include an imager and sounder system, a data collection system, and a search and rescue system. The Space Transportation System and GOES I-M development philosophy and the satellite transfer orbit philosophy are explained. The spacecraft will be launched from the Kennedy Space Center using Atlas G/Centaur D-1A expendable launch vehicles. The coverage required for launch and the support of transfer and drift orbits will consist of the 26-m antenna as prime and the TBD antenna as backup for 11 days at all complexes. There will be contingency support 15 days for on-station spacecraft checkout. After the initial 30 to 45 days, the Deep Space Network (DSN) is committed for emergency support. Contingency and emergency support will be provided by Goldstone only. Information is given in tabular form for DSN support, frequency assignments, telemetry, command, and tracking support responsibility.

  15. Mobile satellite communications from highly inclined elliptic orbits

    NASA Astrophysics Data System (ADS)

    Stuart, J. R.; Norbury, J. A.; Barton, S. K.

    This paper is concerned with the feasibility of developing a commercially profitable land mobile satellite system capable of providing two way voice communications throughout Europe. The traditional Geostationary orbit configuration is compared with two highly inclined elliptical non-GEO orbits; the 12 hour Molniya and 24 hour Tundra. Potentials advantages of elliptical orbits, including resistance to signal fade and blockage and simplicity of a zenith pointing antenna, are assessed against the cost and risks of supporting the two or three satellite constellation necessary to provide continuous 24 hour coverage. Other considerations such as AOCS philosophy, injection strategy, radiation environment and satellite handover strategy are also discussed. The relative merits of the different orbit options are compared in terms of technical performance and overall system cost. The paper concludes that customer needs for low cost reliable mobile voice communications in Europe can best be achieved using a set of communications satellites placed in a highly inclined elliptical orbit.

  16. Estimates of surface ultraviolet radiation over north America using Geostationary Operational Environmental Satellites observations

    NASA Astrophysics Data System (ADS)

    Gadhavi, H.; Pinker, R. T.; Laszlo, I.

    2008-11-01

    Information on ultraviolet (UV) radiative fluxes is needed for public safety, understanding biodiversity, and for chemical transport modeling. Space-based observations can provide homogeneous and systematic estimates of the UV flux over large regions. In the past, UV flux estimates have been made from polar orbiting satellites; such estimates lack information on diurnal variability that can result in significant errors in UV dose (diurnally integrated UV flux). An algorithm has been developed to estimate diurnally varying spectral UV flux at the surface based on information from geostationary satellites (cloud amount, surface albedo and aerosols) and from polar orbiting satellites (ozone). Algorithm evaluation is done by comparison with ground-based observations made between January 1998 and December 2000 over eighteen stations of the United States Department of Agriculture (USDA)'s UV monitoring network. A good agreement between ground-based observations and satellite estimates is found with a mean bias (satellite - ground) of +3.5% for all-sky (cloudy + clear) cases. A negative mean bias of the same magnitude is found for clear-sky cases. Root mean square (RMS) differences are 25% and 14% for all-sky and clear-sky cases, respectively. Using simulations, it is shown that when only one observation near noontime is used to estimate UV dose, errors in the range of -61% to 48% can result, depending on cloud conditions. The RMS difference is 9% and it increases to 13% when off-noon hour (±2 hrs) observations are used to estimate the UV flux over Queenstown, MD.

  17. 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.

  18. Synergistic Opportunities for the Geostationary Satellite Constellation: Status of the CEOS Activity

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    This talk will summarize activities of the Committee on Earth Observation Satellites (CEOS) Atmospheric Composition Constellation (ACC) to collaboratively advance the next generation of air quality monitoring from space. Over the past 2 years, CEOS ACC have developed a position paper describing the benefits to be derived from such collaboration. The resulting ACC recommendations were endorsed by CEOS in May 2011. We will discuss next steps toward implementing this vision, starting with a new 3-year CEOS Action in 2012. Several countries and space agencies are currently planning to launch geostationary Earth orbit (GEO) missions in 2017-2022 to obtain atmospheric composition measurements for characterizing anthropogenic and natural distributions of tropospheric ozone, aerosols, and their precursors. These missions include Europe's ESA Sentinel-4 with EUMETSAT IRS, the United States' NASA GEO-CAPE, Korea's ME/MEST/KARI GEMS, and Japan's JAXA GMAP-Asia. GEO observations offer a quantum advance in air quality monitoring from space by providing measurements many times per day. However, a single GEO satellite views only a portion of the globe. These satellites, positioned to view Europe, East Asia, and North America, will collectively provide hourly coverage of the industrialized Northern Hemisphere at similar spatial resolutions. Planned low Earth orbit (LEO) missions will provide complementary daily global observations. Observations from a single LEO satellite will overlap those from each GEO satellite once per day, providing a means for combining the GEO observations and a necessary perspective for interpreting global impacts of smaller scale processes. The EUMETSAT Metop series, NOAA/NASA JPSS series, and ESA Sentinel-5 Precursor and Sentinel-5 missions will each provide such daily overlap with the GEO missions. The Canadian PCW PHEMOS mission will make an additional unique suite of observations. PCW will provide quasi-geostationary coverage over the Arctic that overlaps with each geostationary satellite over 30N - 60N, adding opportunities for intercalibration many times per day. The development of common data products, data distribution protocols, and calibration strategies will synergistically enable critically needed understanding of the interactions between regional and global atmospheric composition. Common air quality trace gas products will be tropospheric column O3, NO2, HCHO, and SO2 nominally at 8 km spatial resolution and 1 hour temporal frequency. Detection of aerosols in the UV will allow absorbing aerosols to be distinguished from total aerosol optical depth, providing information on aerosol speciation and particularly relevant to the air quality/climate interface associated with aerosol radiative forcing. Such activities 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 in their own regions.

  19. Geostationary-satellite beacon-receiver array for studies of ionospheric irregularities

    SciTech Connect

    Carlos, R.C.; Jacobson, A.R.; Wu, Guanghui.

    1992-01-01

    Ionospheric irregularities can be studied by various techniques. These include widely spaced Doppler sounders or ionosondes, Faraday rotation polarimetry, and two-frequency differential Doppler, and radio interferometry. With geostationary satellites, one usually uses Faraday rotation of the beacon signal to measure the ionospheric TEC. With a network of polarimeters, the horizontal wave parameters of Traveling Ionospheric Disturbances (TIDS) can be deduced, but the shortcoming of this technique is its poor sensitivity. This paper describes a geostationary-satellite beacon-receiver array at Los Alamos, New Mexico, which will be employed for the studying of ionospheric irregularities, especially the fine-scale TIDS.

  20. Geostationary-satellite beacon-receiver array for studies of ionospheric irregularities

    SciTech Connect

    Carlos, R.C.; Jacobson, A.R.; Wu, Guanghui

    1992-09-01

    Ionospheric irregularities can be studied by various techniques. These include widely spaced Doppler sounders or ionosondes, Faraday rotation polarimetry, and two-frequency differential Doppler, and radio interferometry. With geostationary satellites, one usually uses Faraday rotation of the beacon signal to measure the ionospheric TEC. With a network of polarimeters, the horizontal wave parameters of Traveling Ionospheric Disturbances (TIDS) can be deduced, but the shortcoming of this technique is its poor sensitivity. This paper describes a geostationary-satellite beacon-receiver array at Los Alamos, New Mexico, which will be employed for the studying of ionospheric irregularities, especially the fine-scale TIDS.

  1. On the remote sensing of mesoscale tropical convection intensity from a geostationary satellite.

    NASA Technical Reports Server (NTRS)

    Sikdar, D. N.; Suomi, V. E.

    1972-01-01

    This paper develops an objective technique for estimating the mass and energy exchange in convection systems corresponding to altocumulus cumulogenitus and cumulonimbus intensities using measurements of the area change of the cirrus outflow on a sequence of satellite cloud photographs obtained at geostationary altitude. The data clearly show that: (1) the technique is able to isolate vigorous and moderate convection regimes on the geostationary satellite cloud photos; and (2) the model-estimated mass and energy are consistent with ground-based measurements such as those of Braham and Brown.

  2. Multiple-baseline detection of a geostationary satellite with the Navy Precision Optical Interferometer

    NASA Astrophysics Data System (ADS)

    Armstrong, J. T.; Baines, Ellyn K.; Schmitt, Henrique R.; Restaino, Sergio R.; Clark, James H.; Benson, James A.; Hutter, Donald J.; Zavala, Robert T.

    2015-09-01

    We describe multi-baseline observations of a geostationary satellite using the Navy Precision Optical Interferometer (NPOI) during the glint season of March 2015. We succeeded in detecting DirecTV-7S with an interferometer baseline length of 8.8 m on two nights, with a brief simultaneous detection at 9.8 m baseline length on the second night. These baseline lengths correspond to a resolution of ~4 m at geostationary altitude. This is the first multiple-baseline interferometric detection of a satellite.

  3. Combined Use of Polar and Geostationary Satellite Sensors For Aerosol Characterization Over The Ocean

    NASA Astrophysics Data System (ADS)

    Costa, M. J.; Cervino, M.; Levizzani, V.; Silva, A. M.

    Aerosol particles play an important role in the Earth's climate due to their direct and indirect interaction with the atmosphere. Monitoring of the optical properties of atmospheric aerosol is thus crucial for a radiative forcing quantification at the lo- cal, regional and global scales. Ground-based measurements provide accurate aerosol properties. However, given the strong spatial and temporal variability of tropospheric aerosols ground measurements cannot cover the global scale. On the other hand, satellite-based algorithms for aerosol retrievals presently do not match the accuracy of ground-based results. Most satellite algorithms are based on a single sensor, thus often suffering from specific limitations (poor spatial or spectral resolution, long re- visitation time, poor cloud mask). A method to exploit the synergy between the polar orbiting Global Ozone Monitoring Experiment (GOME) onboard ERS-2 and the METEOSAT geostationary system was proposed (Costa et al., 2001), aiming at increasing the accuracy of the aerosol charac- terization and monitoring of the optical thickness. A validation of the algorithm is done by comparing satellite retrievals with results obtained via independent space-time co- located ground-based measurements from AERONET (Aerosol Robotic NETwork) and from other state of the art algorithms that make use of satellite measurements such as the MODIS official aerosol product. Results of the ongoing validation are pre- sented for relevant transport events of desert dust and biomass burning aerosol over the Atlantic and Indian Oceans during year 2000. References: Costa,M.J., M.Cervino, E.Cattani, F.Torricella, V.Levizzani, and A.M.Silva, 2001: "Aerosol characterization and optical thickness retrievals using GOME and METEOSAT satellite data". Meteor. Atmos. Phys., (in press). Acknowledgements: METEOSAT imagery was kindly made available by EUMET- SAT. We thank the AERONET investigators and their staff for establishing and main- taining the sites used in this investigation. MJC was financially supported by the Sub- programa Cincia e Tecnologia do Segundo Quadro Comunitrio de Apoio.

  4. Geostationary satellite positioning by DLR/GSOC operations and management methods

    NASA Technical Reports Server (NTRS)

    Brittinger, Peter

    1994-01-01

    Starting with a short description of the GSOC (German Space Operations Center) and its role within the wider framework of the research institute DLR, this paper provides a review of the geostationary telecommunications satellites positioned by the GSOC. The paper then proceeds to describe the evolution of the operations and management structures and methods which have been effectively used to accomplish these missions.

  5. 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.

  6. Energetic particle dropouts observed in the morning sector by the geostationary satellite GEOS-2

    SciTech Connect

    Kopanyi, V.; Korth, A.

    1995-01-01

    The authors report the obervation of particle flux dropout events by the geostationary satellite GEOS-2 in the local dawn sector during the recovery phase of a series of magnetic storms. These dropouts manifested themselves both in ion and electron fluxes. During the events reported, the spacecraft remained in the magnetosphere, so they cannot be interpreted as due to maganetopause crossings.

  7. 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.

  8. 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).

  9. The science benefits of and the antenna requirements for microwave remote sensing from geostationary orbit

    NASA Technical Reports Server (NTRS)

    Stutzman, Warren L. (Editor); Brown, Gary S. (Editor)

    1991-01-01

    The primary objective of the Large Space Antenna (LSA) Science Panel was to evaluate the science benefits that can be realized with a 25-meter class antenna in a microwave/millimeter wave remote sensing system in geostationary orbit. The panel concluded that a 25-meter or larger antenna in geostationary orbit can serve significant passive remote sensing needs in the 10 to 60 GHz frequency range, including measurements of precipitation, water vapor, atmospheric temperature profile, ocean surface wind speed, oceanic cloud liquid water content, and snow cover. In addition, cloud base height, atmospheric wind profile, and ocean currents can potentially be measured using active sensors with the 25-meter antenna. Other environmental parameters, particularly those that do not require high temporal resolution, are better served by low Earth orbit based sensors.

  10. Conservation of the geostationary spectrum

    NASA Astrophysics Data System (ADS)

    Weiss, H. J.

    The present investigation is concerned with the identification and characterization of those technical factors which would have the most significant impact on frequency reuse in communications satellite systems using the geostationary orbit and, hence, on the number of accesses to the geostationary orbit spectrum. Attention is given to the development of a frequency reuse model, the application of the model equation, intra-satellite frequency reuse, polarization discrimination, permissible interference, homogeneity, geometry maintenance, and high frequencies. It is found that satellite antenna technology is a highly significant factor for the frequency reuse potential.

  11. Analysing the Advantages of High Temporal Resolution Geostationary MSG SEVIRI Data Compared to Polar Operational Environmental Satellite Data for Land Surface Monitoring in Africa

    NASA Technical Reports Server (NTRS)

    Fensholt, R.; Anyamba, A.; Huber, S.; Proud, S. R.; Tucker, C. J.; Small, J.; Pak, E.; Rasmussen, M. O.; Sandholt, I.; Shisanya, C.

    2011-01-01

    Since 1972, satellite remote sensing of the environment has been dominated by polar-orbiting sensors providing useful data for monitoring the earth s natural resources. However their observation and monitoring capacity are inhibited by daily to monthly looks for any given ground surface which often is obscured by frequent and persistent cloud cover creating large gaps in time series measurements. The launch of the Meteosat Second Generation (MSG) satellite into geostationary orbit has opened new opportunities for land surface monitoring. The Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument on-board MSG with an imaging capability every 15 minutes which is substantially greater than any temporal resolution that can be obtained from existing polar operational environmental satellites (POES) systems currently in use for environmental monitoring. Different areas of the African continent were affected by droughts and floods in 2008 caused by periods of abnormally low and high rainfall, respectively. Based on the effectiveness of monitoring these events from Earth Observation (EO) data the current analyses show that the new generation of geostationary remote sensing data can provide higher temporal resolution cloud-free (less than 5 days) measurements of the environment as compared to existing POES systems. SEVIRI MSG 5-day continental scale composites will enable rapid assessment of environmental conditions and improved early warning of disasters for the African continent such as flooding or droughts. The high temporal resolution geostationary data will complement existing higher spatial resolution polar-orbiting satellite data for various dynamic environmental and natural resource applications of terrestrial ecosystems.

  12. Geostationary Satellite (GSAT) Failure; an Analysis and Possible Attitude Control Remedy

    NASA Astrophysics Data System (ADS)

    Kumar, Krishna; Singh, Sanjay

    A geostationary satellite has reportedly failed during its orbit raising maneuvers from the GTO to its final stationary ring. It was felt that the failure was possibly caused by differential propellant rates of flow from the symmetrically placed pair of liquid tanks on either side of the center of mass. Alternatively even the initial fixed center-of-mass offset could have led to the same outcome. The investigation presented here models the problem as one of attitude motion by separately treating the system mass into two parts: fixed mass structure including the motor tanks and differentially shrinking bodies of liquid propellant. The system with variable mass is assumed to undergo pitching librations under the influence of thrust moments about the shifting center of mass in the orbital plane. The detailed numerical simulation is undertaken to assess the influence of pitching excitation caused by asymmetric thrusting. The effect of this attitude motion on possible reduction in velocity increment due to thrust misalignment is found to be quite significant. Besides some additional attitude control fuel may also be required to undo the pitching excitation. The simulation carried out here for the case of fixed center-of-mass offset leads to the same general adverse behavior. Finally, a suitable feedback control strategy proposed here is employed to regulate the differential flow rate in symmetrically placed pair of liquid tanks on either side of the center of mass in order to eliminate the adverse effect of the moving center of mass and instead make judicious use for attitude control. It is shown that the feedback control of fuel flow rate in this design with symmetrically laid liquid tanks can help in conserving the fuel, the precious commodity on board and thus significantly enhance the performance of orbit raising maneuvers and hence much higher reliability for mission success.

  13. General relativity and satellite orbits

    NASA Technical Reports Server (NTRS)

    Rubincam, D. P.

    1975-01-01

    The general relativistic correction to the position of a satellite is found by retaining Newtonian physics for an observer on the satellite and introducing a potential. The potential is expanded in terms of the Keplerian elements of the orbit and substituted in Lagrange's equations. Integration of the equations shows that a typical earth satellite with small orbital eccentricity is displaced by about 17 cm. from its unperturbed position after a single orbit, while the periodic displacement over the orbit reaches a maximum of about 3 cm. The moon is displaced by about the same amounts. Application of the equations to Mercury gives a total displacement of about 58 km. after one orbit and a maximum periodic displacement of about 12 km.

  14. Precise orbit determination of Beidou Satellites at GFZ

    NASA Astrophysics Data System (ADS)

    Deng, Zhiguo; Ge, Maorong; Uhlemann, Maik; Zhao, Qile

    2014-05-01

    In December 2012 the Signal-In-Space Interface Control Document (ICD) of the BeiDou Navigation Satellite System (BeiDou system) was published. Currently the initial BeiDou regional navigation satellite system consisting of 14 satellites was completed, and provides observation data of five Geostationary-Earth-Orbit (GEO)satellites, five Inclined-GeoSynchronous-Orbit (IGSO) satellites and four Medium-Earth-Orbit (MEO) satellites. The Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences (GFZ) contributes as one of the analysis centers to the International GNSS Service (IGS) since many years. In 2012 the IGS began the "Multi GNSS EXperiment" (MGEX), which supports the new GNSS, such as Galileo, Compass, and QZSS. Based on tracking data of BeiDou-capable receivers from the MGEX and chinese BeiDou networks up to 45 global distributed stations are selected to estimate orbit and clock parameters of the GPS/BeiDou satellites. Some selected results from the combined GPS/BeiDou data processing with 10 weeks of data from 2013 are shown. The quality of the orbit and clock products are assessed by means of orbit overlap statistics, clock stabilities as well as an independent validation with SLR measurements. At the end an outlook about GFZ AC's future Multi-GNSS activities will be given.

  15. Feasibility study for Geo-Stationary satellite observation of tropospheric pollutants

    NASA Astrophysics Data System (ADS)

    Sagi, K.; Baron, P.; Dupuy, E.; Suzuki, K.; Kita, K.; Imasu, R.; Kasai, Y.

    2009-04-01

    Geostationary Earth Orbit (GEO) satellites are useful to monitor variations and transport of tropospheric pollutants because of the achievable time resolution (1-2 hour) and horizontal resolution, and because they can perform day and night observations. The Japan Society of Atmospheric Chemistry (JSAC) and the Japanese Space Exploration Agency (JAXA) initiated concept studies for a geostationary satellite to observe pollutant species in Asia1). Instruments operating in three distinct spectral domains: ultraviolet/visible (UV/VIS), thermal infrared (TIR), and microwave are considered for this project. We present the sensitivity studies for a TIR instrument. The necessary trade-off between the signal-to-noise ratio (SNR) and the frequency resolution is a key factor in the definition of the instrumental design. The purpose of this study is to determine the instrumental frequency resolution needed to optimize the trade-off between the sensor parameters (SNR) and the scientific requirements of the project ("Detection of ozone variations in the boundary layer, and tropospheric CO measurements). The scientific requirements in terms of minimum precision (or error) values are 10% for ozone in the boundary layer and 20% for CO tropospheric column. The forward calculation and the retrieval simulations, including a complete error analysis, were performed using the AMATERAS model developed within the NICT-THz remote sensing project2). Retrieval calculation and error analysis are based on the optimal estimation method2). Two scenarii are used for the simulation: an Asian background case and a city polluted case. O3 can be retrieved in the boundary layer with a maximum error of 14% for a frequency resolution = 0.2 cm-1and an instrumental SNR = 600, in the Asian background case. TIR is not the optimal frequency domain for observing tropospheric CO with good sensitivity, but is adequate to measure the altitude abundance profile and the day and night variations of CO at 2000 cm-1. The frequency resolution used must be better than 0.2 cm-1 (SNR = 40) or 0.1 cm-1 (SNR = 20) in polluted conditions, in order to achieve an error level of less than 20%. 1) http://www.stelab.nagoya-u.ac.jp/ste-www1/div1/taikiken/eisei/eisei2.pdf Japanese version only. English version will be available in March 2009. 2) Baron, P., Mendrok, J., Kasai, Y., Ochiai, S., Seta, T., Sagi, K., Suzuki, K., Sagawa, H., and Urban, J., "AMATERASU: Model for Atmospheric TeraHertz Radiation Analysis and Simulation", Journal of the National Institute of Information and Communications Technology, 55, 109-121 (2008).

  16. On the use of satellites in Molniya orbit for meteorological and oceanographic observations of the high latitudes

    NASA Technical Reports Server (NTRS)

    Kidder, Stanley Q.

    1992-01-01

    Two types of orbits are currently used for meteorological satellites: geostationary orbit and low earth orbit. Neither orbit serves the high latitudes well. The Soviet Molniya satellites fly in a highly elliptic orbit inclined 63.4 deg to the equator. For approximately 8 h of its 12-h orbit, a satellite in Molniya orbit is synchronized with the earth such that it is nearly geostationary in the high latitudes. A meteorological/oceanographic satellite in Molniya orbit would bring nearly the same frequent imaging capability to the high latitudes which the tropics and mid-latitudes now enjoy. The uses of such a satellite include Arctic forecasting, study of polar lows, high latitude precipitation estimation, Antarctic studies, sea ice monitoring, and ozone measurements.

  17. 1.6 GHz distress radio call system (DRCS) via geostationary satellite (Inmarsat-E) - Results of the preoperational demonstration

    NASA Astrophysics Data System (ADS)

    Goebel, Walter

    1990-10-01

    The paper discusses features and operations of the spaceborne Emergency Position Indicating Radio Beacons (EPIRBs) system for distress alerting, which is expected to be used on every ship by August 1, 1993. Two types of EPIRBs that were developed to date are described: the floatable EPIRB, used by vessels over 300 GRT (convention ships subjected to the IMO rules) and the hand-held EPIRB used by smaller vessels such as fishing boats or yachts. The transmitted message formats of both are fully compatible. The distress alerts are presently transmitted through the polar orbiting satellite service at 406 MHz. However, the 36th Inmarsat Council in 1990 passed a decision to the effect that the Inmarsat geostationary satellite shall provide service at 1.6 GHz.

  18. 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.

  19. The Study and Applications of Satellite and Satellite Constellation Autonomous Orbit Determination Using Star Sensor

    NASA Astrophysics Data System (ADS)

    Gan, Q. B.

    2012-07-01

    Autonomous satellite orbit determination is a key technique in autonomous satellite navigation. Many kinds of technologies have been proposed to realize the autonomous satellite navigation, such as the star sensor, the Earth magnetometer, the occultation time survey, and the phase measurement of X-ray pulsar signals. This dissertation studies a method of autonomous satellite orbit determination using star sensor. Moreover, the method is extended to the autonomous navigation of satellite constellation and the space-based surveillance. In chapters 1 and 2, some usual time and reference systems are introduced. Then the principles of several typical autonomous navigation methods, and their merits and shortcomings are analyzed. In chapter 3, the autonomous satellite orbit determination using star sensor and infrared Earth sensor (IRES) is specifically studied, which is based on the status movement simulation, the stellar background observation from star sensor, and the Earth center direction survey from IRES. By simulating the low Earth orbit satellites and pseudo Geostationary Earth orbit (PGEO) satellites, the precision of position and speed with autonomous orbit determination using star sensor is obtained. Besides, the autonomous orbit determination using star sensor with double detectors is studied. According to the observation equation's characters, an optimized type of star sensor and IRES initial assembly model is proposed. In the study of the PGEO autonomous orbit determination, an efficient sampling frequency of measurements is promoted. The simulation results confirm that the autonomous satellite orbit determination using star sensor is feasible for satellites with all kinds of altitudes. In chapter 4, the method of autonomous satellite orbit determination using star sensor is extended to the autonomous navigation of mini-satellite constellation. Combining with the high-accuracy inter satellite links data, the precision of the determined orbit and constellation configuration is higher than that ever expected. In chapter 5, two related pre-project researches are developed with respect to the space-based satellite surveillance. One solves the un-convergence question in the preliminary orbit determination and finds an advantageous preliminary orbit determination using inter satellite angle measurement. In the other pre-project research, a creative space-based satellite surveillance model is proposed, which is based on the autonomous surveillance platform navigation. Using the star sensor's navigation data associated with the inter satellite angle measurement, the orbit parameters of the tracking space objects and the surveillance platform are determined. Compared to the available experiment results overseas, the preliminary orbit determination method and the autonomous navigation surveillance platform model are found to be feasible. The research will significantly contribute to the new conception of ``space awareness'', as well as our country's space security construction.

  20. Orbit determination in satellite geodesy

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    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 in several respects: (1) orbits have to be determined for a new class of celestial objects, namely for artificial Earth satellites; (2) new observation types, in particular topocentric distances and radial velocities, are available for the establishment of highly accurate satellite orbits; (3) even for comparatively short arcs (up to a few revolutions) the orbit model that has to be used is much more complicated than for comparable problems in the planetary system: in addition to the gravitational perturbations due to Moon and planets higher-order terms in the Earth's gravity field have to be taken into account as well as non-gravitational effects like atmospheric drag and/or radiation pressure; (4) the parameter space is often of higher than the sixth dimension, because not only the six osculating elements referring to the initial epoch of an arc, but dynamical parameters defining the (a priori imperfectly known) force field have to be determined, as well. It may even be necessary to account for stochastic velocity changes. Orbit determination is not a well-known task in satellit geodesy. This is mainly due to the fact that orbit determination is often imbedded in a much more general parameter estimation problem, where other parameter types (referred to station positions, Earth rotation, atmosphere, etc.) have to be determined, as well. Three examples of "pure" orbit determination problems will be discussed subsequently: ? The first problem intends to optimize the observation process of one Satellite Laser Ranging (SLR) observatory. It is a filter problem, where the orbit is improved in real time with the goal to narrow down the so-called range-gate, defining the time interval when the echo of the LASER pulse is expected. ? Secondly we highlight orbit determination procedures (in particular advanced orbit parametrization techniques) related to the determination of the orbits of GPS satellites and of Low Earth Orbiters (LEOS) equipped with GPS receivers. ? We conclude by discussing the problem of determining the orbits of passive artificial satellites or of space debris using high-precision astrometric CCD-observations of these object.

  1. Monitoring high-ozone events in the US Intermountain West using TEMPO geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Zoogman, P.; Jacob, D. J.; Chance, K.; Liu, X.; Lin, M.; Fiore, A.; Travis, K.

    2014-06-01

    High-ozone events, approaching or exceeding the National Ambient Air Quality Standard (NAAQS), are frequently observed in the US Intermountain West in association with subsiding air from the free troposphere. Monitoring and attribution of these events is problematic because of the sparsity of the current network of surface measurements and lack of vertical information. We present an Observing System Simulation Experiment (OSSE) to evaluate the ability of the future geostationary satellite instrument Tropospheric Emissions: Monitoring of Pollution (TEMPO), scheduled for launch in 2018-2019, to monitor and attribute high-ozone events in the Intermountain West through data assimilation. TEMPO will observe ozone in the ultraviolet (UV) and visible (Vis) bands to provide sensitivity in the lower troposphere. Our OSSE uses ozone data from the GFDL AM3 chemistry-climate model (CCM) as the "true" atmosphere and samples it for April-June 2010 with the current surface network (CASTNet -Clean Air Status and Trends Network- sites), a configuration designed to represent TEMPO, and a low Earth orbit (LEO) IR (infrared) satellite instrument. These synthetic data are then assimilated into the GEOS-Chem chemical transport model (CTM) using a Kalman filter. Error correlation length scales (500 km in horizontal, 1.7 km in vertical) extend the range of influence of observations. We show that assimilation of surface data alone does not adequately detect high-ozone events in the Intermountain West. Assimilation of TEMPO data greatly improves the monitoring capability, with little information added from the LEO instrument. The vertical information from TEMPO further enables the attribution of NAAQS exceedances to background ozone. This is illustrated with the case of a stratospheric intrusion.

  2. 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.

  3. Multiple-Baseline Detection of a Geostationary Satellite with the Navy Precision Optical Interferometer

    NASA Astrophysics Data System (ADS)

    Schmitt, H.; Armstrong, J. T.; Baines, E. K.; Restaino, S. R.; Clark, J. H., III; Benson, J. A.; Hutter, D. J.; Zavala, R. T.

    Using the Navy Precision Optical Interferometer (NPOI), we have made the first multiple-baseline interferometric detection of a satellite. The observations, carried out during the March 2015 glint season, succeeded in detecting the DirecTV-7S satellite with interferometer baseline lengths of 8.8 m and 9.8 m and wavelengths from 850 nm to 550 nm, corresponding to a resolution of ~0.02 arcsec, or 4 m at geostationary altitude. This is the first multiple-baseline interferometric detection of a satellite.

  4. 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.

  5. 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.

  6. 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.

  7. 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).

  8. Analyzing long observation arcs for objects with high area-to-mass ratios in geostationary orbits

    NASA Astrophysics Data System (ADS)

    Musci, R.; Schildknecht, T.; Ploner, M.

    2010-03-01

    A new population of objects with high area-to-mass ratios (AMR) in the geostationary orbit (GEO) has been identified recently. The first observations of this new type of objects were acquired in the framework of the European Space Agency's (ESA) search for space debris in the GEO and the geostationary transfer orbit using ESA's 1-m telescope on Tenerife (ESASDT). Since 2005 some of the newly detected objects with high AMR have been maintained in a catalogue. In addition to the ESASDT, the 1-m telescope of the Astronomical Institute of the University of Bern (AIUB) in Zimmerwald and several instruments located in the region of the former Soviet Union have been used to acquire the observations needed to maintain the orbital elements of these objects. The data from the latter telescopes is provided to AIUB by the Keldysh Institute of Applied Mathematics (KIAM) in the framework of a collaboration. Observation arcs of up to more than three years are currently available for some objects with high AMR. These long observation arcs are used to study the quality of the orbit determination and in particular of the AMR estimation. The results are presented in this paper. Furthermore, the challenges to maintain these orbits, e.g., to recover the objects after several days or weeks, are discussed.

  9. The orbit of Pluto's satellite

    NASA Technical Reports Server (NTRS)

    Tholen, D. J.

    1985-01-01

    Nineteen speckle interferometric observations of the Pluto system have been used to improve the determination of the orbital elements for Pluto's satellite. Calibration uncertainties appear to be the dominant source of error, but the observation of a partial occultation of the satellite by Pluto has been used to constrain the orbit solution. The orbital period is found to be in excellent agreement with the rotational period of the planet, reinforcing the belief that the system is completely tidally evolved. The orbital radius and period imply a total mass for the system of 6.8 + or - 0.5 x 10 to the -9th solar masses. Density constraints place an upper limit of 3615 + or - 90 km on the diameter of Pluto, while observations of the first mutual events establish a crude lower limit of about 2800 km.

  10. Pulse strobing in VLBI for observation of geostationary earth satellites.

    NASA Astrophysics Data System (ADS)

    Gorodetskij, V. M.

    The possibility of broadband synthesis by pulse strobing for observation of slow-moving objects using standard MARK-1 VLBI processing methods is discussed. The possibility of increasing the SNR by using a special type of pulse function is indicated. A specific scheme for application of the method in satellite radiointerferometry is examined.

  11. Identification of geostationary satellites using polarization data from unresolved images

    NASA Astrophysics Data System (ADS)

    Speicher, Andy

    In order to protect critical military and commercial space assets, the United States Space Surveillance Network must have the ability to positively identify and characterize all space objects. Unfortunately, positive identification and characterization of space objects is a manual and labor intensive process today since even large telescopes cannot provide resolved images of most space objects. Since resolved images of geosynchronous satellites are not technically feasible with current technology, another method of distinguishing space objects was explored that exploits the polarization signature from unresolved images. The objective of this study was to collect and analyze visible-spectrum polarization data from unresolved images of geosynchronous satellites taken over various solar phase angles. Different collection geometries were used to evaluate the polarization contribution of solar arrays, thermal control materials, antennas, and the satellite bus as the solar phase angle changed. Since materials on space objects age due to the space environment, it was postulated that their polarization signature may change enough to allow discrimination of identical satellites launched at different times. The instrumentation used in this experiment was a United States Air Force Academy (USAFA) Department of Physics system that consists of a 20-inch Ritchey-Chretien telescope and a dual focal plane optical train fed with a polarizing beam splitter. A rigorous calibration of the system was performed that included corrections for pixel bias, dark current, and response. Additionally, the two channel polarimeter was calibrated by experimentally determining the Mueller matrix for the system and relating image intensity at the two cameras to Stokes parameters S0 and S1. After the system calibration, polarization data was collected during three nights on eight geosynchronous satellites built by various manufacturers and launched several years apart. Three pairs of the eight satellites were identical buses to determine if identical buses could be correctly differentiated. When Stokes parameters were plotted against time and solar phase angle, the data indicates that there were distinguishing features in S0 (total intensity) and S1 (linear polarization) that may lead to positive identification or classification of each satellite.

  12. Near-real-time global biomass burning emissions product from geostationary satellite constellation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyang; Kondragunta, Shobha; Ram, Jessica; Schmidt, Christopher; Huang, Ho-Chun

    2012-07-01

    Near-real-time estimates of biomass burning emissions are crucial for air quality monitoring and forecasting. We present here the first near-real-time global biomass burning emission product from geostationary satellites (GBBEP-Geo) produced from satellite-derived fire radiative power (FRP) for individual fire pixels. Specifically, the FRP is retrieved using WF_ABBA V65 (wildfire automated biomass burning algorithm) from a network of multiple geostationary satellites. The network consists of two Geostationary Operational Environmental Satellites (GOES) which are operated by the National Oceanic and Atmospheric Administration, the Meteosat second-generation satellites (Meteosat-09) operated by the European Organisation for the Exploitation of Meteorological Satellites, and the Multifunctional Transport Satellite (MTSAT) operated by the Japan Meteorological Agency. These satellites observe wildfires at an interval of 15-30 min. Because of the impacts from sensor saturation, cloud cover, and background surface, the FRP values are generally not continuously observed. The missing observations are simulated by combining the available instantaneous FRP observations within a day and a set of representative climatological diurnal patterns of FRP for various ecosystems. Finally, the simulated diurnal variation in FRP is applied to quantify biomass combustion and emissions in individual fire pixels with a latency of 1 day. By analyzing global patterns in hourly biomass burning emissions in 2010, we find that peak fire season varied greatly and that annual wildfires burned 1.33 1012 kg dry mass, released 1.27 1010 kg of PM2.5 (particulate mass for particles with diameter <2.5 ?m) and 1.18 1011kg of CO globally (excluding most parts of boreal Asia, the Middle East, and India because of no coverage from geostationary satellites). The biomass burning emissions were mostly released from forest and savanna fires in Africa, South America, and North America. Evaluation of emission result reveals that the GBBEP-Geo estimates are comparable with other FRP-derived estimates in Africa, while the results are generally smaller than most of the other global products that were derived from burned area and fuel loading. However, the daily emissions estimated from GOES FRP over the United States are generally consistent with those modeled from GOES burned area and MODIS (Moderate Resolution Imaging Spectroradiometer) fuel loading, which produces an overall bias of 5.7% and a correlation slope of 0.97 0.2. It is expected that near-real-time hourly emissions from GBBEP-Geo could provide a crucial component for atmospheric and chemical transport modelers to forecast air quality and weather conditions.

  13. Satellite Orbital Interpolation Comparison Methods

    NASA Astrophysics Data System (ADS)

    Richard, J.-Y.; Deleflie, F.; Gambis, D.

    2012-04-01

    A satellite or artificial probe orbit is made of time series of orbital elements such as state vectors (position and velocities, keplerian orbital elements) given at regular or irregular time intervals. These time series are fitted to observations, so that differences between observations (distance, radial velocity) and the theoretical quantity be minimal, according to a statistical criterion, mostly based on the least-squared algorithm. These computations are carried out using dedicated software, such as the GINS used by GRGS, mainly at CNES Toulouse and Paris Observatory. From an operational point of view, time series of orbital elements are 7-day long. Depending on the dynamical configurations, more generally, they can typically vary from a couple of days to some weeks. One of the fundamental parameters to be adjusted is the initial state vector. This can lead to time gaps, at the level of a few dozen of centimeters between the last point of a time series to the first one of the following data set. The objective of this presentation consists in the improvement of an interpolation method freed itself of such possible "discontinuities" resulting between satellite's orbit arcs when a new initial bulletin is adjusted. We show the principles of interpolation for these time series and compare solutions coming from different interpolation methods such as Lagrange polynomial, spline cubic, Chebyshev orthogonal polynomial and cubic Hermite polynomial. These polynomial coefficients are used to reconstruct and interpolate the satellite orbits without time gaps and discontinuities and requiring a weak memory size.

  14. On-orbit control of the Communications Technology Satellite (CTS)/HERMES

    NASA Technical Reports Server (NTRS)

    Raine, H. R.

    1980-01-01

    A variety of control functions for the CIS HERMES satellite are reviewed. Its mission, to demonstrate high power SHF (12 GHz) transmission is discussed. The satellite was controlled in geostationary orbit for nearly four years from the satellite control center in Ottawa, Canada. Highlights of these operations are outlined. The interactions between many of the automatic onboard control functions and control from the ground are described. Special emphasis is placed on the characteristics and performance of the three axis attitude control system.

  15. 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.

  16. 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.

  17. Lightning data study in conjunction with geostationary satellite data

    NASA Technical Reports Server (NTRS)

    Auvine, Brian; Martin, David W.

    1987-01-01

    During the summer of 1985, cloud-to-ground stroke lightning were collected. Thirty minute samples of lightning were compared with GOES IR fractional cold cloud coverage computed for three temperature thresholds (213, 243, and 273 K) twice daily (morning and evening). It was found that satellite measurements of cold cloud have a relationship to the flashrate and, in a more limited way, to the polarity and numbers of return strokes. Results varied little by location. Lightning, especially positive strokes, was found to be correlated with fractional cloud coverage, especially for clouds at or below 213 K. Other data and correlations are discussed.

  18. 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).

  19. A k-permutation algorithm for Fixed Satellite Service orbital allotments

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    A satellite system synthesis problem, the satellite location problem (SLP), is addressed in this paper. In SLP, orbital locations (longitudes) are allotted to geostationary satellites in the Fixed Satellite Service. A linear mixed-integer programming model is presented that views SLP as a combination of two problems: (1) the problem of ordering the satellites and (2) the problem of locating the satellites given some ordering. A special-purpose heuristic procedure, a k-permutation algorithm, that has been developed to find solutions to SLPs formulated in the manner suggested is described. Solutions to small example problems are presented and analyzed.

  20. Finding fixed satellite service orbital allotments with a k-permutation algorithm

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    A satellite system synthesis problem, the satellite location problem (SLP), is addressed. In SLP, orbital locations (longitudes) are allotted to geostationary satellites in the fixed satellite service. A linear mixed-integer programming model is presented that views SLP as a combination of two problems: the problem of ordering the satellites and the problem of locating the satellites given some ordering. A special-purpose heuristic procedure, a k-permutation algorithm, has been developed to find solutions to SLPs. Solutions to small sample problems are presented and analyzed on the basis of calculated interferences.

  1. Studies of lightning data in conjunction with geostationary satellite data

    NASA Technical Reports Server (NTRS)

    Auvine, B.; Martin, D.

    1985-01-01

    Since January, work has been proceeding on the first phase of this project: the creation of an extensive real-time lightning data base accessible via the Space Science and Engineering Center McIdas system. The purpose of this endeavor is two-fold: to enhance the availability and ease of access to lightning data among the various networks, governmental and research agencies; and to test the feasiblity and desirability of such efforts in succeeding years. The final steps in the creation of the necessary communications links, hardware, and software are in the process of being completed. Operations ground rules for access among the various users have been discussed and are being refined. While the research planned for the last year of the project will rely for the most part on archived, quality-controlled data from the various networks, the real-time data will provide a valuable first-look at potentially interesting case studies. For this purpose, tools are being developed on McIdas for display and analysis of the data as they become available. In conjunction with concurrent GOES real-time imagery, strike locations can be plotted, gridded and contoured, or displayed in various statistical formats including frequency distributions, histograms, and scatter plots. The user may also perform these functions in relation to arbitrarily defined areas on the satellite image. By mid-May these preparations for the access and analysis of real-time lightning data are expected to be complete.

  2. Hazard of collisions in geostationary ring

    NASA Astrophysics Data System (ADS)

    Klimyk, V. U.; Kizyun, L. M.

    2005-06-01

    A probability of catalogue satellites collision in the geostationary orbit is calculated. The direct method is applied: the dangerous rendezvouses of the satellites are determined, and a probability of collisions under the dangerous rendezvouses is calculated. A density of distribution of the uncontrolled satellites coordinates and their orbital elements is obtained. A density of distribution of the directions and values of the relative velocities under dangerous rendezvouses of the geosynchronous satellites is also calculated.

  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. 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.

  5. Upper-Tropospheric Winds Derived from Geostationary Satellite Water Vapor Observations

    NASA Technical Reports Server (NTRS)

    Velden, Christopher S.; Hayden, Christopher M.; Nieman, Steven J.; Menzel, W. Paul; Wanzong, Steven; Goerss, James S.

    1997-01-01

    The coverage and quality of remotely sensed upper-tropospheric moisture parameters have improved considerably with the deployment of a new generation of operational geostationary meteorological satellites: GOES-8/9 and GMS-5. The GOES-8/9 water vapor imaging capabilities have increased as a result of improved radiometric sensitivity and higher spatial resolution. The addition of a water vapor sensing channel on the latest GMS permits nearly global viewing of upper-tropospheric water vapor (when joined with GOES and Meteosat) and enhances the commonality of geostationary meteorological satellite observing capabilities. Upper-tropospheric motions derived from sequential water vapor imagery provided by these satellites can be objectively extracted by automated techniques. Wind fields can be deduced in both cloudy and cloud-free environments. In addition to the spatially coherent nature of these vector fields, the GOES-8/9 multispectral water vapor sensing capabilities allow for determination of wind fields over multiple tropospheric layers in cloud-free environments. This article provides an update on the latest efforts to extract water vapor motion displacements over meteorological scales ranging from subsynoptic to global. The potential applications of these data to impact operations, numerical assimilation and prediction, and research studies are discussed.

  6. 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

  7. Comparison of Geomagnetically-shielded Solar Energetic Proton Fluxes Observed at Geostationary Orbit by GOES and in Low-earth Orbit by SAMPEX, POES and MetOp

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. V.; Mazur, J. E.; Green, J. C.; Machol, J. L.

    2012-12-01

    On the current (13-15) and upcoming (R+) series of NOAA Geostationary Operational Environmental Satellites (GOES), solar protons are observed from each satellite in the eastward and westward directions. Solar protons that arrive at a given location in the inner magnetosphere have energies greater than their geomagnetic cutoffs, which depend on direction of arrival as well as the strength of geomagnetic disturbances. Protons arriving from the west at geostationary orbit (GEO) have much lower geomagnetic cutoff energies than protons arriving from the east. As a result, GOES westward observations of >4 MeV protons are representative of the interplanetary population near Earth and serve as the basis for NOAA's real-time solar radiation storm alerts. While the GOES westward observations are similar to the Solar, Anomalous and Magnetospheric Particle Explorer (SAMPEX) Proton-Electron Telescope (PET) proton observations in the polar cap (above invariant L = 10), GOES eastward observations more closely approximate the PET observations at invariant L = 4-4.5 in low earth orbit (LEO). Therefore, GOES may potentially provide a real-time, two-point estimate of the radial gradient of solar energetic protons between L = 6.6 and L = 4. However, the PET observations at L = 4-4.5 exhibit a much wider range of variability than the GOES eastward observations. Therefore, the purpose of this study is to determine how representative the GOES two-point gradient estimate is as a function of magnetic local time and geographic longitude. The study encompasses the largest solar proton events (SPE) in Solar Cycle 23 and to date in Solar Cycle 24. From April 1998 through December 2006, GOES 10 provides eastward GEO and SAMPEX PET provides LEO observations of large SPEs. The Solar Cycle 24 GEO observations are provided by GOES 13 and 15. From July 1998 to date, the Space Environment Monitors (SEM-2) on the NOAA Polar Operational Environmental Satellites (POES) and EUMETSAT MetOp-A provide SPE observations in additional LEO orbit planes (six as of August 2012). SEM-2 data that are severely contaminated by relativistic electrons are excluded from the study.

  8. The Geostationary Lightning Mapper (GLM) for the GOES-R Series Next Generation Operational Environmental Satellite Constellation

    NASA Technical Reports Server (NTRS)

    Goodman, Steven J.; Blakeslee, Richard; Koshak, William; Petersen, Walter; Carey, Larry; Mach, Douglas; Buechler, Dennis; Bateman, Monte; McCaul, Eugene; Bruning, Eric; Albrecht, Rachel; MacGorman, Donald

    2010-01-01

    The next generation Geostationary Operational Environmental Satellite (GOES-R) series with a planned launch in 2015 is a follow on to the existing GOES system currently operating over the Western Hemisphere. The system will aid in forecasting severe storms and tornado activity, and convective weather impacts on aviation safety and efficiency. The system provides products including lightning, cloud properties, rainfall rate, volcanic ash, air quality, hurricane intensity, and fire/hot spot characterization. Advancements over current GOES include a new capability for total lightning detection (cloud and cloud-to-ground flashes) from the Geostationary Lightning Mapper (GLM), and improved spectral, spatial, and temporal resolution for the 16-channel Advanced Baseline Imager (ABI). The Geostationary Lightning Mapper (GLM), an optical transient detector will map total (in-cloud and cloud-to-ground) lightning flashes continuously day and night with near-uniform spatial resolution of 8 km with a product refresh rate of less than 20 sec over the Americas and adjacent oceanic regions, from the west coast of Africa (GOES-E) to New Zealand (GOES-W) when the constellation is fully operational. In parallel with the instrument development, a GOES-R Risk Reduction Team and Algorithm Working Group Lightning Applications Team have begun to develop the higher level algorithms and applications using the GLM alone and decision aids incorporating information from the ABI, ground-based weather radar, and numerical models. Proxy total lightning data from the NASA Lightning Imaging Sensor on the Tropical Rainfall Measuring Mission (TRMM) satellite and regional lightning networks are being used to develop the pre-launch algorithms and applications, and also improve our knowledge of thunderstorm initiation and evolution. Real time total lightning mapping data are also being provided in an experimental mode to selected National Weather Service (NWS) national centers and forecast offices via the GOES-R Proving Ground to help improve our understanding of the application of these data in operational settings and facilitate early on-orbit user readiness for this new capability.

  9. Thermal physical property-based fusion of geostationary meteorological satellite visible and infrared channel images.

    PubMed

    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

  10. 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

  11. 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.

  12. Plans for EUMETSATs Third Generation Meteosat geostationary satellite programme

    NASA Astrophysics Data System (ADS)

    Stuhlmann, R.; Rodriguez, A.; Tjemkes, S.; Grandell, J.; Arriaga, A.; Bzy, J.-L.; Aminou, D.; Bensi, P.

    The second generation of Meteosat satellites is expected to provide operational services at least until 2015. Considering the time required for the definition phases of new space systems their typical development cycle and the approval of complex programmes, it is necessary to start planning for follow-up geostationary missions already now. EUMETSAT has therefore established a User Consultation Process aimed at capturing the foreseeable high-level user/service needs and priorities of the EUMETSAT Customers and users in the 2015-2025 timeframe. This process led to a first definition of the Third Generation Meteosat (MTG) European geostationary satellite system, which currently consists of a total of five observation missions defined for pre-phase A studies at system level under ESA contract to be started in autumn 2004. The paper gives an overview on the current status of definition of the five observation missions, and a brief description of the MTG schedule and related milestones. Results of scientific studies and presentations/conclusions of MTG User Consultation Workshops and dedicated expert workshops conducted to define the MTG candidate missions are openly available from the EUMETSAT web-page www.eumetsat.de, under the sub-directory 'Preparation of Future Programmes/Meteosat Third Generation (MTG)'.

  13. Thermal-distortion analysis of a spacecraft box truss in geostationary orbit

    NASA Technical Reports Server (NTRS)

    Cosgrove, Patrick A.; Farmer, Jeffery T.; Rowell, Lawrence F.

    1990-01-01

    The Mission to Planet Earth enlists the use of a geostationary platform to support Earth science monitoring instruments. The strongback for a proposed geostationary platform is a deployable box truss that supports two large diameter passive microwave radiometer (PMR) and several other science instruments. A study was performed to estimate the north-south and east-west pointing errors at the mounting locations of the two PMRs due to on-orbit thermal distortions of the main truss. The baseline configuration indicated that the east-west pointing error greatly exceeded the required limits. Primary origins of the pointing errors were identified, and methods for their reduction were discussed. Thermal performance enhancements to the truss structure were modeled and analyzed, including state-of-the-art surface coatings and insulation techniques. Comparisons of the thermal enhancements to the baseline were performed. Results demonstrated that using a thermal enclosure insulating technique reduced external heat fluxes, and distributed those heat fluxes more evenly throughout the structure, sufficiently reducing the pointing error to satisfy pointing accuracy requirements for the PMR's.

  14. 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.

  15. 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.

  16. Investigations of the evolution of optical characteristics and dynamics of proper rotation of uncontrolled geostationary artificial satellites

    NASA Astrophysics Data System (ADS)

    Papushev, P.; Karavaev, Yu.; Mishina, M.

    2009-05-01

    On the base of the photometrical data an analysis of the periods and light curves of the uncontrolled artificial satellites was performed. The equipment used in the observations of the satellites is fast photoelectrical photometer attached to the astronomical telescopes of the Sayan observatory (operated by the ISTP SB RAS). Two-mirror Cassegrain telescope with 0.5 m aperture equipped photoelectrical photometer setup in the fast photometry mode have the ability to track the slow moving objects up to 15-th visual magnitude. The observations started from the second half of the 20-th century and have been continued up to the present time. The standard photometric Johnson-Morgan system UBVR had been used. The basic goals are to present observational data and both discuss the probability of detection of design changes of satellite being a long time in geostationary orbit, and display the periods behavior rarely discussed in the literature. A systematization of the rotation periods is submitted. The light curves of the uncontrolled objects has periodic structure and specific mirror spike features which are a characteristic for identification of an object. Analysis of the standard color index (CI) value can provide additional data on the mirror spike origin. When mirror spikes are eliminated color indexes (B-V) for the diffuse component of the satellites is in the range of 0.9-1.1 and exceed those for the solar type star. Unlike, mirror spikes CI (B-V) are close to zero or negative, indicating a blue excess of radiation spectrum. The processes of the variation rotation periods connected with the satellites construction and their interaction with space environment are discussed.

  17. System Approach to the Forecast of Electron Fluxes iAT Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Balikhin, M. A.; Boynton, R. J.; Billings, S. A.; Pakhotin, I. P.

    2012-12-01

    A black box input-output NARMAX approach has been used to develop a one day ahead forecast of the electron fluxes at geostationary orbit. ACE measurements are used as the system inputs and GOES spacecraft data as outputs. An online real time forecasting tool has been developed as the result to this approach, which is available on the Sheffield R. Boynton www page http://www.acse.shef.ac.uk/~cop08rjb/2MeV_EF.html. This tool provides more accurate forecast in comparison to presently available online tools based on local wave acceleration models. As NARMAX provides physically interpretable results, the model terms are analysed in order to improve understanding of underlying physical processes. The identified NARMAX model indicates a significance of solar wind density in the control of high energy electron fluxes. Such a density dependence can be explained as a consequence of ULF pulsations. The alternative explanation relates it to the dynamics of EMIC waves.

  18. 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.

  19. Low earth orbit satellite/terrestrial mobile service compatibility

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  20. Derivation and evaluation of land surface temperature from the geostationary operational environmental satellite series

    NASA Astrophysics Data System (ADS)

    Fang, Li

    The Geostationary Operational Environmental Satellites (GOES) have been continuously monitoring the earth surface since 1970, providing valuable and intensive data from a very broad range of wavelengths, day and night. The National Oceanic and Atmospheric Administration's (NOAA's) National Environmental Satellite, Data, and Information Service (NESDIS) is currently operating GOES-15 and GOES-13. The design of the GOES series is now heading to the 4 th generation. GOES-R, as a representative of the new generation of the GOES series, is scheduled to be launched in 2015 with higher spatial and temporal resolution images and full-time soundings. These frequent observations provided by GOES Image make them attractive for deriving information on the diurnal land surface temperature (LST) cycle and diurnal temperature range (DTR). These parameters are of great value for research on the Earth's diurnal variability and climate change. Accurate derivation of satellite-based LSTs from thermal infrared data has long been an interesting and challenging research area. To better support the research on climate change, the generation of consistent GOES LST products for both GOES-East and GOES-West from operational dataset as well as historical archive is in great demand. The derivation of GOES LST products and the evaluation of proposed retrieval methods are two major objectives of this study. Literature relevant to satellite-based LST retrieval techniques was reviewed. Specifically, the evolution of two LST algorithm families and LST retrieval methods for geostationary satellites were summarized in this dissertation. Literature relevant to the evaluation of satellite-based LSTs was also reviewed. All the existing methods are a valuable reference to develop the GOES LST product. The primary objective of this dissertation is the development of models for deriving consistent GOES LSTs with high spatial and high temporal coverage. Proper LST retrieval algorithms were studied according to the characteristics of the imager onboard the GOES series. For the GOES 8-11 and GOES R series with split window (SW) channels, a new temperature and emissivity separation (TES) approach was proposed for deriving LST and LSE simultaneously by using multiple-temporal satellite observations. Two split-window regression formulas were selected for this approach, and two satellite observations over the same geo-location within a certain time interval were utilized. This method is particularly applicable to geostationary satellite missions from which qualified multiple-temporal observations are available. For the GOES M(12)-Q series without SW channels, the dual-window LST algorithm was adopted to derive LST. Instead of using the conventional training method to generate coefficients for the LST regression algorithms, a machine training technique was introduced to automatically select the criteria and the boundary of the sub-ranges for generating algorithm coefficients under different conditions. A software package was developed to produce a brand new GOES LST product from both operational GOES measurements and historical archive. The system layers of the software and related system input and output were illustrated in this work. Comprehensive evaluation of GOES LST products was conducted by validating products against multiple ground-based LST observations, LST products from fine-resolution satellites (e.g. MODIS) and GSIP LST products. The key issues relevant to the cloud diffraction effect were studied as well. GOES measurements as well as ancillary data, including satellite and solar geometry, water vapor, cloud mask, land emissivity etc., were collected to generate GOES LST products. In addition, multiple in situ temperature measurements were collected to test the performance of the proposed GOES LST retrieval algorithms. The ground-based dataset included direct surface temperature measurements from the Atmospheric Radiation Measurement program (ARM), and indirect measurements (surface long-wave radiation observations) from the SURFace RADiation Budget (SURF

  1. The atmospheric composition geostationary satellite constellation for air quality and climate science: Evaluating performance with Observation System Simulation Experiments

    NASA Astrophysics Data System (ADS)

    Edwards, D. P.; Barre, J.; Worden, H. M.; Arellano, A. F.; Gaubert, B.; Anderson, J. L.; Mizzi, A. P.; Lahoz, W. A.

    2014-12-01

    Current satellite observations of tropospheric composition made from low Earth orbit provide at best one or two measurements each day at any given location. Coverage is global but sparse, often with large uncertainties in individual measurements that limit examination of local and regional atmospheric composition over short time periods. This has hindered the operational uptake of these data for monitoring air quality and population exposure, and for initializing and evaluating chemical weather forecasts. By the end of the current decade there are planned 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 GEO platforms to achieve continuous time-resolved high-density observations of continental domains for mapping pollutant sources and variability on diurnal and local scales. We describe Observing System Simulation Experiments (OSSEs) to evaluate the contributions of these GEO missions to improve knowledge of near-surface air pollution due to intercontinental long-range transport and quantify chemical precursor emissions. We discuss the requirements on measurement simulation, chemical transport modeling, and data assimilation for a successful OSSE infrastructure. Our approach uses an efficient computational method to sample a high-resolution global GEOS-5 chemistry Nature Run over each geographical region of the GEO constellation. The demonstration carbon monoxide (CO) observation simulator, which is being expanded to other chemical pollutants, currently produces multispectral retrievals and captures realistic scene-dependent variation in measurement vertical sensitivity and cloud cover. We use the DART Ensemble Adjustment Kalman Filter to assimilate the simulated observations in a CAM-Chem global chemistry-climate model Control Run. The impact of observing over each region is evaluated using data denial experiments. Finally, we report on international collaborations using the OSSE approach to determine expected performance of planned satellite systems and set requirements for future missions.

  2. Linked Autonomous Interplanetary Satellite Orbit Navigation

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.; Anderson, Rodney L.; Born, George H.; Leonard, Jason M.; McGranaghan, Ryan M.; Fujimoto, Kohei

    2013-01-01

    A navigation technology known as LiAISON (Linked Autonomous Interplanetary Satellite Orbit Navigation) has been known to produce very impressive navigation results for scenarios involving two or more cooperative satellites near the Moon, such that at least one satellite must be in an orbit significantly perturbed by the Earth, such as a lunar halo orbit. The two (or more) satellites track each other using satellite-to-satellite range and/or range-rate measurements. These relative measurements yield absolute orbit navigation when one of the satellites is in a lunar halo orbit, or the like. The geometry between a lunar halo orbiter and a GEO satellite continuously changes, which dramatically improves the information content of a satellite-to-satellite tracking signal. The geometrical variations include significant out-of-plane shifts, as well as inplane shifts. Further, the GEO satellite is almost continuously in view of a lunar halo orbiter. High-fidelity simulations demonstrate that LiAISON technology improves the navigation of GEO orbiters by an order of magnitude, relative to standard ground tracking. If a GEO satellite is navigated using LiAISON- only tracking measurements, its position is typically known to better than 10 meters. If LiAISON measurements are combined with simple radiometric ground observations, then the satellite s position is typically known to better than 3 meters, which is substantially better than the current state of GEO navigation. There are two features of LiAISON that are novel and advantageous compared with conventional satellite navigation. First, ordinary satellite-to-satellite tracking data only provides relative navigation of each satellite. The novelty is the placement of one navigation satellite in an orbit that is significantly perturbed by both the Earth and the Moon. A navigation satellite can track other satellites elsewhere in the Earth-Moon system and acquire knowledge about both satellites absolute positions and velocities, as well as relative positions and velocities in space. The second novelty is that ordinarily one requires many satellites in order to achieve full navigation of any given customer s position and velocity over time. With LiAISON navigation, only a single navigation satellite is needed, provided that the satellite is significantly affected by the gravity of the Earth and the Moon. That single satellite can track another satellite elsewhere in the Earth- Moon system and obtain absolute knowledge of both satellites states.

  3. 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.

  4. Orbit computation of the TELECOM-2D satellite with a Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Deleflie, Florent; Coulot, David; Vienne, Alain; Decosta, Romain; Richard, Pascal; Lasri, Mohammed Amjad

    2014-07-01

    In order to test a preliminary orbit determination method, we fit an orbit of the geostationary satellite TELECOM-2D, as if we did not know any a priori information on its trajectory. The method is based on a genetic algorithm coupled to an analytical propagator of the trajectory, that is used over a couple of days, and that uses a whole set of altazimutal data that are acquired by the tracking network made up of the two TAROT telescopes. The adjusted orbit is then compared to a numerical reference. The method is described, and the results are analyzed, as a step towards an operational method of preliminary orbit determination for uncatalogued objects.

  5. THE ORBITS OF THE OUTER URANIAN SATELLITES

    SciTech Connect

    Brozovic, M.; Jacobson, R. A.

    2009-04-15

    We report on the numerically integrated orbits for the nine outer Uranian satellites. The orbits are calculated based on fits to the astrometric observations for the period from 1984 to 2006. The results include the state vectors, post-fit residuals, and mean orbital elements. We also assess the accuracy of the orbital fits and discuss the need for future measurements.

  6. An Analytical Satellite Orbit Predictor (ASOP)

    NASA Technical Reports Server (NTRS)

    Starke, S. E.

    1977-01-01

    The documentation and user's guide for the Analytical Satellite Orbit Predictor (ASOP) computer program is presented. The ASOP is based on mathematical methods that represent a new state-of-the-art for rapid orbit computation techniques. It is intended to be used for computation of near-earth orbits including those of the shuttle/orbiter and its payloads.

  7. Retrieval of fire radiative power and biomass combustion using the Korean geostationary meteorological satellite

    NASA Astrophysics Data System (ADS)

    Kim, D. S.; Lee, Y. W.

    2013-10-01

    Global warming induced by greenhouse gases is increasing wildfire frequencies and scale. Since wildfire again releases greenhouse gases(GHGs) into the air, the vicious cycle is repeated. Satellite remote sensing is a useful tool for detecting wildfire. However, estimating the GHGs emission from wildfire has not been challenged yet. Wildfires are estimated to be responsible for, on average, around 30% of global total CO emissions, 10% of methane emissions, 38% of tropospheric ozone, and over 86% of black carbon. So we need to quantify the emitted gases by biomass combustions, which can be measured by the FRP (fire radiative power) derived from the spectral characteristics of satellite sensors. This paper described the algorithm for retrieval of FRP using COMS(Communication, Ocean and Meteorological Satellite), the Korean geostationary meteorological satellite. The FRP of wildfire is retrieved by single waveband methods suitable to COMS channels. The retrieval of FRP is dependent on the emissivity of each bandwidth. So, we used MODIS NDVI through a spatio-temporal calibration for the emissivity calculations. We made sure that the FRP in wildfire pixel is much higher than its spatially and temporally neighboring pixels. For future work, we should quantify the relationships between FRP and the biomass combustion according to fuel types.

  8. Cloud pattern prediction from geostationary meteorological satellite images for solar energy forecasting

    NASA Astrophysics Data System (ADS)

    Cros, S.; Sbastien, N.; Liandrat, O.; Schmutz, N.

    2014-10-01

    Surface solar radiation forecasting permits to predict photovoltaic plant production for a massive and safe integration of solar energy into the electric network. For short-term forecasts (intra-day), methods using images from meteorological geostationary satellites are more suitable than numerical weather prediction models. Forecast schemes consist in assessing cloud motion vectors and in extrapolating cloud patterns from a given satellite image in order to predict cloud cover state above a PV plant. Atmospheric motion vectors retrieval techniques have been studied for several decades in order to improve weather forecasts. However, solar energy forecasting requires the extraction of cloud motion vectors on a finer spatial- and time-resolution than those provided for weather forecast applications. Even if motion vector retrieval is a wide research field in image processing related topics, only block-matching techniques are operationally used for solar energy forecasts via satellite images. In this paper, we propose two motion vectors extraction methods originating from video compression techniques (correlation phase and optical flow methods). We implemented them on a 6-day dataset of Meteosat-10 satellite diurnal images. We proceeded to cloud pattern extrapolation and compared predicted cloud maps against actual ones at different time horizons from 15 minutes to 4 hours ahead. Forecast scores were compared to the state-of-the-art (block matching) method. Correlation phase methods do not outperform block-matching but their computation time is about 25 times shorter. Optical flow based method outperforms all the methods with a satisfactory time computing.

  9. 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.

  10. 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.

  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. 47 CFR 25.142 - Licensing provisions for the non-voice, non-geostationary Mobile-Satellite Service.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... must identify the power flux density produced at the Earth's surface by each space station of their... § 25.202(f) (1), (2) and (3), as calculated for a fixed point on the Earth's surface in the plane of... shared by those earth stations of non-voice, non-geostationary mobile-satellite service systems that...

  13. 47 CFR 25.142 - Licensing provisions for the non-voice, non-geostationary Mobile-Satellite Service.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... must identify the power flux density produced at the Earth's surface by each space station of their... § 25.202(f) (1), (2) and (3), as calculated for a fixed point on the Earth's surface in the plane of... shared by those earth stations of non-voice, non-geostationary mobile-satellite service systems that...

  14. Sea surface temperature from the new Japanese geostationary meteorological Himawari-8 satellite

    NASA Astrophysics Data System (ADS)

    Kurihara, Yukio; Murakami, Hiroshi; Kachi, Misako

    2016-02-01

    Himawari-8 is a new geostationary meteorological satellite operated by the Japan Meteorological Agency (JMA). The Earth Observation Research Center of the Japan Aerospace Exploration Agency in collaboration with the JMA produces skin sea surface temperatures (SSTs) from Himawari-8 data. A new quasi-physical algorithm was used to calculate SSTs. Cloud screening based on the Bayesian inference method was used to detect cloudy pixels. Himawari-8 SSTs from June to September 2015 were compared with drifting and tropical moored buoy data. This comparison showed a root-mean-square difference of ˜0.59 K and a bias of ˜-0.16 K against the buoy data. Positive and variable biases were found in seas along the viewing boundaries.

  15. The effects of non-sphericity on geostationary satellite retrievals of dust aerosols

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Liu, Xiong; Christopher, Sundar A.; Reid, Jeffrey S.; Reid, Elizabeth; Maring, Hal

    2003-12-01

    Using data collected during the Puerto Rico Dust Experiment (PRIDE), we examine the effect of non-spherical phase functions on dust aerosol retrievals from geostationary satellites. We utilize a statistical model based on Scanning Electron Micrograph (SEM) analysis of individual dust particles. Using T-matrix calculations and assuming that dust particles are randomly-orientated oblate spheroids we compute the dust phase function and scattering properties. Although the non-spherical function developed in this study compares well with the synthetic non-spherical phase functions [Liu et al., 2003], new retrievals using the non-spherical phase function only show slight improvement at scattering angles (?) from 110 ~ 150, and become worse for ? between 150 ~ 170. However the retrievals are greatly improved at all angles when retrieval algorithms account for the combined effect of both spherical and non-spherical phase functions.

  16. True Color Images of the Earth created with the Geostationary Satellite Instrument MSG SEVIRI

    NASA Astrophysics Data System (ADS)

    Reuter, Maximilian

    2013-04-01

    One of the most famous pictures ever taken was by the crew of Apollo 17 in 1972, showing our Earth from a distance of about 45000km. This picture was named 'Blue Marble' and it reminds us of the beauty and uniqueness of our home planet. With geostationary satellites, such views of the Earth are possible without the need to have a photographer in space. However, up to the present, the production of such Blue Marble type images from geostationary satellite data has been impaired by the lack of channels in the visible spectral region. A method for the generation of full disk MSG (METEOSAT Second Generation) SEVIRI (Scanning-Enhanced Visible and Infrared Imager) true colour composite images will be presented. The algorithm mainly uses the SEVIRI channels VIS006 (0.6μm), NIR008 (0.8μm) and NIR016 (1.6μm). The lack of information in the blue and green parts of the visible spectrum is compensated by using data from NASA's (National Aeronautics and Space Administration's) Blue Marble next generation (BMNG) project to fill a look-up table (LUT) transforming RGB (red/green/blue) false colour composite images of VIS006/NIR008/NIR016 into true colour images. Tabulated radiative transfer calculations of a pure Rayleigh atmosphere are used to add an impression of Rayleigh scattering towards the sunlit horizon. The resulting images satisfy naive expectations: clouds are white or transparent, vegetated surfaces are greenish, deserts are sandy-coloured, the ocean is dark blue to black and a narrow halo due to Rayleigh scattering is visible at the sunlit horizon. Therefore, such images are easily interpretable also for inexperienced users not familiar with the characteristics of typical MSG false colour composite images. The images can be used for scientific applications to illustrate specific meteorological conditions or for non-scientific purposes, for example, for raising awareness in the public of the Earth's worthiness of protection.

  17. 75 FR 17055 - Coordination Between the Non-Geostationary and Geostationary Satellite Orbit

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ... mobile operations and addresses issues raised in the Notice of Proposed Rulemaking (NPRM), 69 FR 4908...\\ NPRM, 69 FR 4908 (Feb. 02, 2004), para. 64 and Appendix B. A. Need for, and Objectives of, the Report... Telecommunications Carriers'' (partial definition); http://www.census.gov/naics/2007/def/ND517110.HTM#N517110 ....

  18. Characterization of urban heat island effects over Asian megacities with hourly LST maps derived from Japanese geostationary satellite data

    NASA Astrophysics Data System (ADS)

    Oyoshi, K.; Tamura, M.

    2009-12-01

    Asian countries are expected to continue economic growth with high rate and urban structure can be transformed dramatically. Urbanization and increase in anthropogenic energy consumption cause urban heat island effect. And, Heat island effect increases cooling cost in summer and induces health problem such as heat stroke. Remotely sensed data can be powerful tool to characterize urban area and measure urban thermal conditions, because it is able to capture spatio-temporal variations in urban environments. Japanese geostationary meteorological satellite, MTSAT which covers east Asia and the western Pacific region from 140 degrees East above the equator was launched in February 2005. MTSAT provides hourly visible and thermal infrared image, and hourly Land Surface Temperature (LST) can be retrieved. Therefore, compared to polar orbiting satellites such as MODIS or AVHRR, MTSAT is expected to characterize urban thermal conditions in much detailed temporal scale. In this study, in order to evaluate thermal conditions over Asian megacities with MTSAT data, we investigated methodology for monitoring urban LST with satellite data and characterize thermal conditions by using hourly LST data. Firstly, LST were retrieved from MTSAT thermal infrared data with split-window algorithm, and it was confirmed that MTSAT is able to capture hourly spatio-temporal changes and detect urban heat island effects. Then, we constructed LST database of Asian megacities and the database was open to public on the WWW (http://eiserv.uee.kyoto-u.ac.jp/MTSAT/LST/index_e.php). Finally, by using developed LST database, characteristics of hourly temperature changes of Asian megacities were compared and categorized. And it is found that these characteristics were depend on urban structure of each city. Near-real time land surface temperature (LST) monitoring system on the WWW. Latest LST images of Asian megacities are displayed on the top page.

  19. Rainfall estimation for real time flood monitoring using geostationary meteorological satellite data

    NASA Astrophysics Data System (ADS)

    Veerakachen, Watcharee; Raksapatcharawong, Mongkol

    2015-09-01

    Rainfall estimation by geostationary meteorological satellite data provides good spatial and temporal resolutions. This is advantageous for real time flood monitoring and warning systems. However, a rainfall estimation algorithm developed in one region needs to be adjusted for another climatic region. This work proposes computationally-efficient rainfall estimation algorithms based on an Infrared Threshold Rainfall (ITR) method calibrated with regional ground truth. Hourly rain gauge data collected from 70 stations around the Chao-Phraya river basin were used for calibration and validation of the algorithms. The algorithm inputs were derived from FY-2E satellite observations consisting of infrared and water vapor imagery. The results were compared with the Global Satellite Mapping of Precipitation (GSMaP) near real time product (GSMaP_NRT) using the probability of detection (POD), root mean square error (RMSE) and linear correlation coefficient (CC) as performance indices. Comparison with the GSMaP_NRT product for real time monitoring purpose shows that hourly rain estimates from the proposed algorithm with the error adjustment technique (ITR_EA) offers higher POD and approximately the same RMSE and CC with less data latency.

  20. Solar global horizontal and direct normal irradiation maps in Spain derived from geostationary satellites

    NASA Astrophysics Data System (ADS)

    Polo, J.

    2015-08-01

    Solar radiation derived from satellite imagery is a powerful and highly accurate technique for solar resource assessment due to its maturity and to the long term database of observation images available. This work presents the methodology developed at CIEMAT for mapping solar radiation from geostationary satellite information and it also shows solar irradiation maps of global horizontal and direct normal components elaborated for Spain. The maps presented here have been developed from daily solar irradiation estimated for eleven years of satellite images (2001-2011). An attempt to evaluate the uncertainty of the presented maps is made using ground measurements from 27 meteorological stations available in Spain for global horizontal irradiation obtained from the World Radiation Data Centre. In the case of direct normal irradiation the ground measurement database was scarce, having available only six ground stations with measurements for a period of 4 years. Yearly values of global horizontal irradiation are around 1800 kWh m-2 in most of the country and around 1950-2000 kWh m-2 for annual direct normal irradiation. Root mean square errors in monthly means were of 11% and of 29% for global horizontal and direct normal irradiation, respectively.

  1. A versatile system for processing geostationary satellite data with run-time visualization capability

    SciTech Connect

    Landsfeld, M.; Gautier, C.; Figel, T.

    1995-01-01

    To better predict global climate change, scientists are developing climate models that require interdisciplinary and collaborative efforts in their building. The authors are currently involved in several such projects but will briefly discuss activities in support of two such complementary projects: the Atmospheric Radiation Measurement (ARM) program of the Department of Energy and Sequoia 2000, a joint venture of the University of California, the private sector, and government. The author`s contribution to the ARM program is to investigate the role of clouds on the top of the atmosphere and on surface radiance fields through the data analysis of surface and satellite observations and complex modeling of the interaction of radiation with clouds. One of the first ARM research activities involves the computation of the broadband shortwave surface irradiance from satellite observations. Geostationary satellite images centered over the first ARM observation site are received hourly over the Internet network and processed in real time to compute hourly and daily composite shortwave irradiance fields. The images and the results are transferred via a high-speed network to the Sequoia 2000 storage facility in Berkeley, where they are archived. These satellite-derived results are compared with the surface observations to evaluate the accuracy of the satellite estimate and the spatial representation of the surface observations. In developing the software involved in calculating the surface shortwave irradiance, the authors have produced an environment whereby they can easily modify and monitor the data processing as required. Through the principles of modular programming, they have developed software that is easily modified as new algorithms for computation are developed or input data availability changes. In addition, the software was designed so that it could be run from an interactive, icon-driven, graphical interface, TCL-TK, developed by Sequoia 2000 participants.

  2. Half-Hour Rainfall Retrieval based on multispectral geostationary satellite images

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Zhuge, Xiao-Yong

    2015-04-01

    A method for both precipitation area and intensity retrievals is developed based on multispectral geostationary satellite images. This method can be applied to continuous observation of large-scale precipitation so as to solve the problem from the measurements of rainfall radar and rain gauge. Satellite observation is instantaneous, whereas the rain gauge records accumulative data during a time interval, and thus, using the 10-min gauge rainfall data rather than 1-hr gauge rainfall data as the reference value, can obviously improve the accuracy of satellite rainfall retrieval.For this reason, a 10-min rainfall algorithm is established firstly. It includes two steps. 1) A Rainfall probability identification matrix (RPIM) is used to distinguish rainfall clouds from nonrainfall clouds. This RPIM is established by combining infrared brightness temperatures (BTs) with visible reflectivity at daytime and dual-channel brightness temperature differences (BTDs) at nighttime. It is more efficient in improving the retrieval accuracy of rainfall area than previous threshold combination screening methods. 2) the multispectral segmented curve-fitting rainfall algorithm (MSCFRA) is proposed to estimate the 10-min rain rates. Rainfall samples taken from June to August 2008 and 2010 are used to assess the performance of the rainfall algorithm. Assessment results show that the MSCFRA improves the accuracy of rainfall estimation for both stratiform cloud rainfall and convective cloud rainfall. These results are practically consistent with rain gauge measurements in both rainfall area division and rainfall intensity grade estimation. Furthermore, this study demonstrates that the temporal resolution of satellite detection is important and necessary in improving the precision of satellite rainfall retrieval. The current geostationary satellite provides an image every half an hour, so the temporal 'gaps' exist when the satellite images are directly used to retrieve 10-min rainfall. To implement continuous and reliable rainfall retrieval, an immediate tracking and continuous accumulation technique (ITCAT) of half-hour rainfall retrieval is proposed. The ITCAT includes two steps. 1) The cross-correlation method is applied to track cloud-motion currents and establish 10-min-interval image sequences. 2) A continuous retrieval of 10-min rain rate is conducted with the image sequences, and finally a total half-hour rainfall is determined by accumulations. The satellite retrieval tests on the typical precipitation process in summer of 2008 show that, compared with the previous direct rainfall retrieval for half-hour to one-hour, this rainfall retrieval technique significantly improves the retrieval accuracy of rainfall scope and rainfall intensity ranging from slight rain to rainstorm for both real-time monitoring or nowcasting processes. This technique is more effective than the previous algorithm, and the fundamental reason lies in its consideration of the movement of cloud cluster. On this basis, coverage duration of rainfall clouds can be reliably estimated. It is of significance to the retrieval of deep convective cloud rainfall with rapid movement speed and drastic intensity variation. This technique also provides a feasible idea for improving the accuracy of rainfall nowcasting.

  3. Optical Orbit Determination of a Geosynchronous Earth Orbit Satellite Effected by Baseline Distances between Various Ground-based Tracking Stations

    NASA Astrophysics Data System (ADS)

    Son, Ju Young; Jo, Jung Hyun; Choi, Jin; Kim, Bang-Yeop; Yoon, Joh-Na; Yim, Hong-Suh; Choi, Young-Jun; Park, Sun-Youp; Bae, Young Ho; Roh, Dong-Goo; Park, Jang-Hyun; Kim, Ji-Hye

    2015-09-01

    We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS), a Geostationary Earth Orbit (GEO) satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO) of the Korea Astronomy and Space Science Institute (KASI), Optical Wide field Patrol (OWL) at KASI, and the Chungbuk National University Observatory (CNUO) from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS) in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK) was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.

  4. On the reliability of geostationary satellite observations for diagnosing indirect aerosol effects

    NASA Astrophysics Data System (ADS)

    Merk, Daniel; Deneke, Hartwig; Pospichal, Bernhard; Seifert, Patric

    2015-10-01

    Aerosol indirect effects are poorly understand and constitute a highly uncertain anthropogenic forcing of climate change. The interaction of aerosols with clouds together with entrainment and turbulent mixing processes modulate cloud microphysics and radiative effects. In the current study we present preliminary results to diagnose indirect aerosol effects from the synergy of geostationary satellite observations, surface observations and MACC aerosol analysis. We examine if the sub-adiabatic factor - representative for entrainment - can be obtained from the combination of passive-satellite observations with ground-based cloud base height from a ceilometer network. Therefore the uncertainty of the sub-adiabatic factor due to its required input parameters, the cloud geometrical thickness and liquid water path, is explored. We use a two year dataset from SEVIRI and compare it to the LACROS supersite at Leipzig, Germany. We find that the comparison of satellite-retrieved cloud top heights shows a RMSD of 1100 m and the liquid water path of 75 gm-2, which are too large to provide a meaningful estimate of the instantaneous sub-adiabtic factor. Linking the cloud microphysical properties from passive satellites with aerosol properties obtained from MACC, we investigate the Twomey hypothesis, namely that smaller droplets and a higher cloud droplet number concentration result from higher aerosol load for a given liquid water path (positive change). A positive relative change is obtained for aerosol optical depth and the sulphate mass integrated from the surface to the cloud top. In contrast, a negative relative change is however found for sea salt.

  5. Global Assessment of Land Surface Temperature From Geostationary Satellites and Model Estimates

    NASA Technical Reports Server (NTRS)

    Reichle, Rolf H.; Liu, Q.; Minnis, P.; daSilva, A. M., Jr.; Palikonda, R.; Yost, C. R.

    2012-01-01

    Land surface (or 'skin') temperature (LST) lies at the heart of the surface energy balance and is a key variable in weather and climate models. In this research we compare two global and independent data sets: (i) LST retrievals from five geostationary satellites generated at the NASA Langley Research Center (LaRC) and (ii) LST estimates from the quasi-operational NASA GEOS-5 global modeling and assimilation system. The objective is to thoroughly understand both data sets and their systematic differences in preparation for the assimilation of the LaRC LST retrievals into GEOS-5. As expected, mean differences (MD) and root-mean-square differences (RMSD) between modeled and retrieved LST vary tremendously by region and time of day. Typical (absolute) MD values range from 1-3 K in Northern Hemisphere mid-latitude regions to near 10 K in regions where modeled clouds are unrealistic, for example in north-eastern Argentina, Uruguay, Paraguay, and southern Brazil. Typically, model estimates of LST are higher than satellite retrievals during the night and lower during the day. RMSD values range from 1-3 K during the night to 2-5 K during the day, but are larger over the 50-120 W longitude band where the LST retrievals are derived from the FY2E platform

  6. Los Alamos geostationary orbit synoptic data set: a compilation of energetic particle data

    SciTech Connect

    Baker, D.N.; Higbie, P.R.; Belian, R.D.; Aiello, W.P.; Hones, E.W. Jr.; Tech, E.R.; Halbig, M.F.; Payne, J.B.; Robinson, R.; Kedge, S.

    1981-08-01

    Energetic electron (30 to 2000 keV) and proton (145 keV to 150 MeV) measurements made by Los Alamos National Laboratory sensors at geostationary orbit 6.6 R/sub E/ are summarized. The data are plotted in terms of daily average spectra, 3-h local time averages, and in a variety of statistical formats. The data summarize conditions from mid-1976 through 1978 (S/C 1976-059) and from early 1977 through 1978 (S/C 1977-007). The compilations correspond to measurements at 35/sup 0/W, 70/sup 0/W, and 135/sup 0/W geographic longitude and, thus, are indicative of conditions at 9/sup 0/, 11/sup 0/, and 4.8/sup 0/ geomagnetic latitude, respectively. Most of this report is comprised of data plots that are organized according to Carrington solar rotations so that the data can be easily compared to solar rotation-dependent interplanetary data. As shown in prior studies, variations in solar wind conditions modulate particle intensity within the terrestrial magnetosphere. The effects of these variations are demonstrated and discussed. Potential uses of the Synoptic Data Set by the scientific and applications-oriented communities are also discussed.

  7. 0.5-4 Å X-RAY BRIGHTENINGS IN THE MAGNETOSPHERE OBSERVED BY THE GEOSTATIONARY OPERATIONAL ENVIRONMENTAL SATELLITES

    SciTech Connect

    Yamamoto, Tetsuya T.; Miyoshi, Y.

    2013-10-01

    We found 217 X-ray brightening events in Earth's magnetosphere. These events occur in the high-energy band (0.5-4 Å) of the Geostationary Operational Environmental Satellite (GOES) X-ray light curves, although GOES X-ray light curves are frequently used as indices of solar flare magnitudes. We found that (1) brightening events are absent in the low-energy band (1-8 Å), unlike those associated with solar flares; and (2) the peak fluxes, durations, and onset times of these events depend on the magnetic local time (MLT). The events were detected in 2006, 2010, and 2011 at around 19-10 MLT, that is, from night to morning. They typically lasted for 2-3 hr. Their peak fluxes are less than 3 × 10{sup –8} W m{sup –2} in the 0.5-4 Å band and are maximized around 0-5 MLT. From these MLT dependencies, we constructed an MLT time profile of X-ray brightening events. Because 0.5-4 and 1-8 Å fluxes were observed and had the same order of magnitude when GOES 14 passed through Earth's shadow, we expected that X-ray brightening events in the 1-8 Å band are obscured by high-background X-ray fluxes coming from the Sun. We also found coincidence between X-ray brightening events and aurora substorms. In the majority of our events, the minimum geomagnetic field values (AL index) are below –400 nT. From these results and consideration of the GOES satellite orbit, we expect that these X-ray brightening events occur in the magnetosphere. We cannot, however, clarify the radiative process of the observed X-ray brightening events.

  8. Improving the orbits of eclipsing GPS satellites

    NASA Astrophysics Data System (ADS)

    Rodriguez Solano, Carlos Javier; Hugentobler, Urs; Steigenberger, Peter; Allende Alba, Gerardo

    2013-04-01

    The orbits of GPS satellites show a lower performance during Sun-Earth eclipse seasons than during periods outside these seasons. In particular the orbits of GPS II and IIA satellites are worse during eclipses, while GPS IIR satellite orbits are almost unaffected. The cause of this problem is the non-nominal yaw attitude of the satellites during eclipses, i.e., the yaw maneuvers performed at noon, shadow and post-shadow. If the yaw maneuvers are not properly taken into account, two effects appear: 1) the phase measurements are degraded since the modelled position of the satellite's navigation antenna differs from the true position, and 2) the non-conservative forces like solar radiation pressure and Earth radiation pressure are mismodelled due to the wrong orientation of the satellite's surfaces in space. In this study, we introduce the yaw maneuver information available from models in the computation of solar radiation pressure and Earth radiation pressure acting on a box-wing like satellite. Also the computation of the satellite's navigation antenna position takes into account the yaw maneuver models. The improvement of GPS satellite orbits during eclipse seasons is quantified in terms of orbit predictions after 6 hours and after 4 days for all GPS satellites during 2007 and 2008. Already the use of the currently available yaw maneuver models, with nominal hardware yaw rates, shows an important improvement when combined with our box-wing model. In addition, we have estimated the real hardware yaw rates from PPP residuals and use this information for orbit prediction, obtaining an additional improvement in the orbits of GPS II and IIA satellites during eclipse seasons.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Revised Orbits of Saturn's Small Inner Satellites

    NASA Technical Reports Server (NTRS)

    Jacobson, R. A.; Spitale, J.; Porco, C. C.; Beurle, K.; Cooper, N. J.; Evans, M. W.; Murray, C. D.

    2007-01-01

    We have updated the orbits of the small inner Saturnian satellites using additional Cassini imaging observations through 2007 March. Statistically significant changes from previously published values appear in the eccentricities and inclinations of Pan and Daphnis, but only small changes have been found in the estimated orbits of the other satellites. We have also improved our knowledge of the masses of Janus and Epimetheus as a result of their close encounter observed in early 2006.

  15. A versatile system for processing geostationary satellite data with run-time visualization capability

    NASA Technical Reports Server (NTRS)

    Landsfeld, M.; Gautier, C.; Figel, T.

    1995-01-01

    To better predict global climate change, scientists are developing climate models that require interdisciplinary and collaborative efforts in their building. We are currently involved in several such projects but will briefly discuss activities in support of two such complementary projects: the Atmospheric Radiation Measurement (ARM) program of the Department of Energy and Sequoia 2000, a joint venture of the University of California, the private sector, and government agencies. Our contribution to the ARM program is to investigate the role of clouds on the top of the atmosphere and on surface radiance fields through the data analysis of surface and satellite observations and complex modeling of the interaction of radiation with clouds. One of our first ARM research activities involves the computation of the broadband shortwave surface irradiance from satellite observations. Geostationary satellite images centered over the first ARM observation site are received hourly over the Internet network and processed in real time to compute hourly and daily composite shortwave irradiance fields. The images and the results are transferred via a high-speed network to the Sequoia 2000 storage facility in Berkeley, where they are archived These satellite-derived results are compared with the surface observations to evaluate the accuracy of the satellite estimate and the spatial representation of the surface observations. In developing the software involved in calculating the surface shortwave irradiance, we have produced an environment whereby we can easily modify and monitor the data processing as required. Through the principles of modular programming, we have developed software that is easily modified as new algorithms for computation are developed or input data availability changes. In addition, the software was designed so that it could be run from an interactive, icon-driven, graphical interface, TCL-TK, developed by Sequoia 2000 participants. In this way, the data flow can be interactively assessed and altered as needed. In this environment, the intermediate data processing 'images' can be viewed, enabling the investigator to easily monitor the various data processing steps as they progress. Additionally, this environment allows the rapid testing of new processing modules and allows their effects to be visually compared with previous results.

  16. Geostationary Operational Environmental Satellite (GOES)-14 super rapid scan operations to prepare for GOES-R

    NASA Astrophysics Data System (ADS)

    Schmit, Timothy J.; Goodman, Steven J.; Lindsey, Daniel T.; Rabin, Robert M.; Bedka, Kristopher M.; Gunshor, Mathew M.; Cintineo, John L.; Velden, Christopher S.; Scott Bachmeier, A.; Lindstrom, Scott S.; Schmidt, Christopher C.

    2013-01-01

    Geostationary Operational Environmental Satellite (GOES)-14 imager was operated by National Oceanic and Atmospheric Administration (NOAA) in an experimental rapid scan 1-min mode that emulates the high-temporal resolution sampling of the Advanced Baseline Imager (ABI) on the next generation GOES-R series. Imagery with a refresh rate of 1 min of many phenomena were acquired, including clouds, convection, fires, smoke, and hurricanes, including 6 days of Hurricane Sandy through landfall. NOAA had never before operated a GOES in a nearly continuous 1-min mode for such an extended period of time, thereby making these unique datasets to explore the future capabilities possible with GOES-R. The next generation GOES-R imager will be able to routinely take mesoscale (1000 km1000 km) images every 30 s (or two separate locations every minute). These images can be acquired even while scanning continental United States and full disk images. These high time-resolution images from the GOES-14 imager are being used to prepare for the GOES-R era and its advanced imager. This includes both the imagery and quantitative derived products such as cloud-top cooling. Several animations are included to showcase the rapid change of the many phenomena observed during super rapid scan operations for GOES-R (SRSOR).

  17. Diurnal-seasonal and weather-related variations of land surface temperature observed from geostationary satellites

    NASA Astrophysics Data System (ADS)

    Vinnikov, Konstantin Y.; Yu, Yunyue; Rama Varma Raja, M. K.; Tarpley, Dan; Goldberg, Mitchell D.

    2008-11-01

    The time series of clear-sky Land Surface Temperatures (LST) for one year, 2001, obtained from pyrgeometric observations at five selected US surface radiation (SURFRAD) stations and independently retrieved for the locations of these stations from Infrared Imager hourly observations of two geostationary satellites, GOES-8 and GOES-10, are presented as a sum of time-dependent expected value (diurnal and seasonal cycles), and weather-related anomalies. The availability of three independent observations is used to assess random and systematic errors in LST data. Temporal variation of the expected value is approximated as a superposition of the first two annual and diurnal Fourier harmonics. This component of temporal variations of LST absorbs all systematic errors; which themselves are often a subject of diurnal and seasonal variations. The results revealed that the weather-related temporal variation of LST is much smaller than the temporal variations of the expected value, but much larger than the random errors of observation. Scale of temporal autocorrelation of weather-related component of clear-sky LST variations is about 3 days.

  18. Trade-off studies of a hyperspectral infrared sounder on a geostationary satellite.

    PubMed

    Wang, Fang; Li, Jun; Schmit, Timothy J; Ackerman, Steven A

    2007-01-10

    Trade-off studies on spectral coverage, signal-to-noise ratio (SNR), and spectral resolution for a hyperspectral infrared (IR) sounder on a geostationary satellite are summarized. The data density method is applied for the vertical resolution analysis, and the rms error between true and retrieved profiles is used to represent the retrieval accuracy. The effects of spectral coverage, SNR, and spectral resolution on vertical resolution and retrieval accuracy are investigated. The advantages of IR and microwave sounder synergy are also demonstrated. When focusing on instrument performance and data processing, the results from this study show that the preferred spectral coverage combines long-wave infrared (LWIR) with the shorter middle-wave IR (SMidW). Using the appropriate spectral coverage, a hyperspectral IR sounder with appropriate SNR can achieve the required science performance (1 km vertical resolution, 1 K temperature, and 10% relative humidity retrieval accuracy). The synergy of microwave and IR sounders can improve the vertical resolution and retrieval accuracy compared to either instrument alone. PMID:17268565

  19. The geo-control system for station keeping and colocation of geostationary satellites

    NASA Technical Reports Server (NTRS)

    Montenbruck, O.; Eckstein, M. C.; Gonner, J.

    1993-01-01

    GeoControl is a compact but powerful and accurate software system for station keeping of single and colocated satellites, which has been developed at the German Space Operations Center. It includes four core modules for orbit determination (including maneuver estimation), maneuver planning, monitoring of proximities between colocated satellites, and interference and event prediction. A simple database containing state vector and maneuver information at selected epochs is maintained as a central interface between the modules. A menu driven shell utilizing form screens for data input serves as the central user interface. The software is written in Ada and FORTRAN and may be used on VAX workstations or mainframes under the VMS operating system.

  20. 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.

  1. 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.

  2. Satellite Orbital Interpolation using Tchebychev Polynomials

    NASA Astrophysics Data System (ADS)

    Richard, Jean-Yves; Deleflie, Florent; Edorh, Smho

    2014-05-01

    A satellite or artificial probe orbit is made of time series of orbital elements such as state vectors (position and velocities, keplerian orbital elements) given at regular or irregular time intervals. These time series are fitted to observations, so that differences between observations (distance, radial velocity) and the theoretical quantity be minimal, according to a statistical criterion, mostly based on the least-squared algorithm. These computations are carried out using dedicated software, such as the GINS used by GRGS, mainly at CNES Toulouse and Paris Observatory. From an operational point of view, time series of orbital elements are 7-day long. Depending on the dynamical configurations, more generally, they can typically vary from a couple of days to some weeks. One of the fundamental parameters to be adjusted is the initial state vector. This can lead to time gaps, at the level of a few dozen of centimetres between the last point of a time series to the first one of the following data set. The objective of this presentation consists in the improvement of an interpolation method freed itself of such possible "discontinuities" resulting between satellite's orbit arcs when a new initial bulletin is adjusted. We compare solutions of different Satellite Laser Ranging using interpolation methods such as Lagrange polynomial, spline cubic, Tchebychev orthogonal polynomial and cubic Hermite polynomial. These polynomial coefficients are used to reconstruct and interpolate the satellite orbits without time gaps and discontinuities and requiring a weak memory size. In this approach, we have tested the orbital reconstruction using Tchebychev polynomial coefficients for the LAGEOS and Starlette satellites. In this presentation, it is showed that Tchebychev's polynomial interpolation can achieve accuracy in the orbit reconstruction at the sub-centimetre level and allowing a gain of a factor 5 of memory size of the satellite orbit with respect to the Cartesian coordinates' representation.

  3. Comparison of winter-nocturnal geostationary satellite infrared-surface temperature with shelter-height temperature in Florida

    NASA Technical Reports Server (NTRS)

    Chen, E.; Allen, L. H., Jr.; Bartholic, J. F.; Gerber, J. F.

    1983-01-01

    Geostationary satellite surface temperatures derived from a Visible and Infrared Spin Scan Radiometer (VISSR) sensor (10.5 to 12.6 microns) were compared with 1.5-m air temperatures collected by a thermocouple on a traversing vehicle along rural highway transects in Florida, and with two fixed thermographs located in rural and agricultural areas. Statistical comparisons between satellite and 1.5-m observations yielded a mean correlation coefficient of 0.87 and an average sample standard deviation from regression of 1.57 C during clear nights for four winters (1978-1981). The satellite-temperature image of Lake Okeechobee was compared with its geographic outline for areal image registration. Manual overlays of temporal images were repeatable to within one pixel. Satellite-sensed water temperature of Lake Okeechobee was used as an indicator of satellite radiometer repeatability and stability.

  4. Antenna Pointing to the Geo Satellite Using Converted NORAD TLE from Osculating Orbital Elements

    NASA Astrophysics Data System (ADS)

    Lee, Byoung-Sun; Kim, Hae-Yeon; Hwang, Yoola; Kim, Jaehoon

    2007-06-01

    Antenna pointing analysis for a geostationary satellite has been performed for using the NORAD Two-Line-Elements (TLE) converted from osculating Keplerian orbital elements. In order to check the possibility of the reception of the satellite signal, the antenna offset angles have been derived for the Communications, Ocean, and Meteorological Satellite (COMS) which carries out weekly East-West and North-South station-keeping maneuvers and twice a day thruster assisted momentum dumping. Throughout the analysis, it is shown that the use of converted NORAD TLE simplifies the antenna pointing related interfaces in satellite mission control system. For a highly eccentric transfer orbit cases, further analysis presents that the converted NORAD TLE from near apogee gives more favorable results.

  5. 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.

  6. 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.

  7. Lifetimes of lunar satellite orbits

    NASA Technical Reports Server (NTRS)

    Meyer, Kurt W.; Buglia, James J.; Desai, Prasun N.

    1994-01-01

    The Space Exploration Initiative has generated a renewed interest in lunar mission planning. The lunar missions currently under study, unlike the Apollo missions, involve long stay times. Several lunar gravity models have been formulated, but mission planners do not have enough confidence in the proposed models to conduct detailed studies of missions with long stay times. In this report, a particular lunar gravitational model, the Ferrari 5 x 5 model, was chosen to determine the lifetimes for 100-km and 300-km perilune altitude, near-circular parking orbits. The need to analyze orbital lifetimes for a large number of initial orbital parameters was the motivation for the formulation of a simplified gravitational model from the original model. Using this model, orbital lifetimes were found to be heavily dependent on the initial conditions of the nearly circular orbits, particularly the initial inclination and argument of perilune. This selected model yielded lifetime predictions of less than 40 days for some orbits, and other orbits had lifetimes exceeding a year. Although inconsistencies and limitations are inherent in all existing lunar gravity models, primarily because of a lack of information about the far side of the moon, the methods presented in this analysis are suitable for incorporating the moon's nonspherical gravitational effects on the preliminary design level for future lunar mission planning.

  8. 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 μm 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.

  9. 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

  10. Experimental study on the precise orbit determination of the BeiDou navigation satellite system.

    PubMed

    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

  11. Properties of satellite orbits - Ephemerides, dynamical constants, and satellite phenomena

    NASA Technical Reports Server (NTRS)

    Aksnes, K.

    1977-01-01

    A short account is given of the history of the observation of the Galilean satellites, with an emphasis on early orbital work and practical applications thereof to world mapping and navigation. The general character of satellite motion is described from a geometric and physical point of view without reference to mathematics. This is followed by a similar discussion of ordinary and mutual satellite phenomena. The accuracies of published ephemerides are discussed on the basis of the observations and theories available for the various satellites. The ephemeris tables need to be revised and, perhaps, partly replaced by well-documented computer programs. The determination of physical parameters (planetary masses and oblatenesses; masses, sizes, and albedo maps of satellites) from positional observations of satellites and photometric observations of ordinary and mutual satellite phenomena is discussed.

  12. GOCE Satellite Orbit in a Computational Aspect

    NASA Astrophysics Data System (ADS)

    Bobojc, Andrzej; Drozyner, Andrzej

    2013-04-01

    The presented work plays an important role in research of possibility of the Gravity Field and Steady-State Ocean Circulation Explorer Mission (GOCE) satellite orbit improvement using a combination of satellite to satellite tracking high-low (SST- hl) observations and gravity gradient tensor (GGT) measurements. The orbit improvement process will be started from a computed orbit, which should be close to a reference ("true") orbit as much as possible. To realize this objective, various variants of GOCE orbit were generated by means of the Torun Orbit Processor (TOP) software package. The TOP software is based on the Cowell 8th order numerical integration method. This package computes a satellite orbit in the field of gravitational and non-gravitational forces (including the relativistic and empirical accelerations). The three sets of 1-day orbital arcs were computed using selected geopotential models and additional accelerations generated by the Moon, the Sun, the planets, the Earth and ocean tides, the relativity effects. Selected gravity field models include, among other things, the recent models from the GOCE mission and the models such as EIGEN-6S, EIGEN-5S, EIGEN-51C, ITG-GRACE2010S, EGM2008, EGM96. Each set of 1-day orbital arcs corresponds to the GOCE orbit for arbitrary chosen date. The obtained orbits were compared to the GOCE reference orbits (Precise Science Orbits of the GOCE satellite delivered by the European Space Agency) using the root mean squares (RMS) of the differences between the satellite positions in the computed orbits and in the reference ones. These RMS values are a measure of performance of selected geopotential models in terms of GOCE orbit computation. The RMS values are given for the truncated and whole geopotential models. For the three variants with the best fit to the reference orbits, the empirical acceleration models were added to the satellite motion model. It allowed for further improving the fitting of computed orbits to the reference orbits. A linear and non-linear model of empirical accelerations was used. After using the non-linear model, the RMS values were reduced by the factor from about 2 to 3 compared with the linear model. A general form of the non-linear model of empirical accelerations is shown in this work. This model can be scaled to a given set of dynamical data for orbit determination by estimating of 192 parameters. The comparison between the computed orbits and the reference ones was performed with respect to the inertial reference frame (IRF) at J2000.0 epoch. Thus, the given GOCE reference orbits were transformed from ITRF2005 reference frame into IRF frame. It is shown that the velocity components of GOCE reference orbits must be transformed into IRF frame using the full rotation vector of the Earth. In such a case RMS values reach a level of meters.

  13. The validation service of the hydrological SAF geostationary and polar satellite precipitation products

    NASA Astrophysics Data System (ADS)

    Puca, S.; Porcu, F.; Rinollo, A.; Vulpiani, G.; Baguis, P.; Balabanova, S.; Campione, E.; Ertrk, A.; Gabellani, S.; Iwanski, R.; Juraek, M.; Ka?k, J.; Kernyi, J.; Koshinchanov, G.; Kozinarova, G.; Krahe, P.; Lapeta, B.; Lb, E.; Milani, L.; Okon, L'.; ztopal, A.; Pagliara, P.; Pignone, F.; Rachimow, C.; Rebora, N.; Roulin, E.; Snmez, I.; Toniazzo, A.; Biron, D.; Casella, D.; Cattani, E.; Dietrich, S.; Di Paola, F.; Laviola, S.; Levizzani, V.; Melfi, D.; Mugnai, A.; Panegrossi, G.; Petracca, M.; San, P.; Zauli, F.; Rosci, P.; De Leonibus, L.; Agosta, E.; Gattari, F.

    2014-04-01

    The development phase (DP) of the EUMETSAT Satellite Application Facility for Support to Operational Hydrology and Water Management (H-SAF) led to the design and implementation of several precipitation products, after 5 yr (2005-2010) of activity. Presently, five precipitation estimation algorithms based on data from passive microwave and infrared sensors, on board geostationary and sun-synchronous platforms, function in operational mode at the H-SAF hosting institute to provide near real-time precipitation products at different spatial and temporal resolutions. In order to evaluate the precipitation product accuracy, a validation activity has been established since the beginning of the project. A Precipitation Product Validation Group (PPVG) works in parallel with the development of the estimation algorithms with two aims: to provide the algorithm developers with indications to refine algorithms and products, and to evaluate the error structure to be associated with the operational products. In this paper, the framework of the PPVG is presented: (a) the characteristics of the ground reference data available to H-SAF (i.e. radar and rain gauge networks), (b) the agreed upon validation strategy settled among the eight European countries participating in the PPVG, and (c) the steps of the validation procedures. The quality of the reference data is discussed, and the efforts for its improvement are outlined, with special emphasis on the definition of a ground radar quality map and on the implementation of a suitable rain gauge interpolation algorithm. The work done during the H-SAF development phase has led the PPVG to converge into a common validation procedure among the members, taking advantage of the experience acquired by each one of them in the validation of H-SAF products. The methodology is presented here, indicating the main steps of the validation procedure (ground data quality control, spatial interpolation, up-scaling of radar data vs. satellite grid, statistical score evaluation, case study analysis). Finally, an overview of the results is presented, focusing on the monthly statistical indicators, referred to the satellite product performances over different seasons and areas.

  14. Precision orbit determination of altimetric satellites

    NASA Technical Reports Server (NTRS)

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

    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 absolute sea surface topography is that the altimetric satellite orbits be computed with sub-decimeter accuracy within a well defined terrestrial reference frame. SLR tracking in support of precision orbit determination of altimetric satellites is significant. Recent examples are the use of SLR as the primary tracking systems for TOPEX/Poseidon and for ERS-1 precision orbit determination. The current radial orbit accuracy for TOPEX/Poseidon is estimated to be around 3-4 cm, with geographically correlated orbit errors around 2 cm. The significance of the SLR tracking system is its ability to allow altimetric satellites to obtain absolute sea level measurements and thereby provide a link to other altimetry measurement systems for long-term sea level studies. SLR tracking allows the production of precise orbits which are well centered in an accurate terrestrial reference frame. With proper calibration of the radar altimeter, these precise orbits, along with the altimeter measurements, provide long term absolute sea level measurements. The U.S. Navy's Geosat mission is equipped with only Doppler beacons and lacks laser retroreflectors. However, its orbits, and even the Geosat orbits computed using the available full 40-station Tranet tracking network, yield orbits with significant north-south shifts with respect to the IERS terrestrial reference frame. The resulting Geosat sea surface topography will be tilted accordingly, making interpretation of long-term sea level variability studies difficult.

  15. Estimating Surface Energy Fluxes via Assimilation of Land Surface Temperature from Geostationary Operational Environmental Satellites

    NASA Astrophysics Data System (ADS)

    xu, T.; Bateni, S.; Liang, S.

    2013-12-01

    Recently, a number of studies have focused on estimating surface energy fluxes via assimilation of land surface temperature observations into variational data assimilation (VDA) schemes. With a simple soil heat transfer model as the constraint, the surface energy balance equation can be solved based on the VDA techniques. In this study, combined-source (CS) and dual-source (DS) VDA schemes are tested extensively over six FLUXNET sites in USA with grassland, cropland and forest land cover types during the vegetation growing season. The CS model assumes the canopy and soil as a combined source and does not consider their different contributions to total surface energy fluxes, while DS model considers them as different sources. Land surface temperature (LST) data retrieved from geostationary operational environmental satellites (GOES) are assimilated into these two VDA models. The model estimates are compared with sensible and latent heat fluxes measurements obtained from eddy covariance instrument mounted on the flux towers. The results indicate that the performance of the CS and DS models are better in dry and lightly vegetated sites than wet and densely vegetated sites. Also, the DS model outperforms the CS model in all sites, implying that the DS scheme can characterize the physics of the problem better. The six sites-averaged root mean square error (RMSE) of sensible heat flux estimates from the CS and DS schemes are respectively 67.4 and 60.2 W m-2. Corresponding RMSE values for latent heat flux retrievals from the CS and DS VDA models are 123.9 and 109.4 W m-2, respectively.

  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. Evolution of mass density and O+ concentration at geostationary orbit during storm and quiet events

    NASA Astrophysics Data System (ADS)

    Denton, R. E.; Takahashi, K.; Thomsen, M. F.; Borovsky, J. E.; Singer, H. J.; Wang, Y.; Goldstein, J.; Brandt, P. C.; Reinisch, B. W.

    2014-08-01

    We investigated mass density ?m and O+ concentration ?O+?nO+/ne (where nO+ and ne are the O+ and electron density, respectively) during two events, one active and one more quiet. We found ?m from observations of Alfvn wave frequencies measured by the GOES, and we investigated composition by combining measurements of ?m with measurements of ion density nMPA,i from the Magnetospheric Plasma Analyzer (MPA) instrument on Los Alamos National Laboratory spacecraft or ne from the Radio Plasma Imager instrument on the Imager for Magnetopause-to-Aurora Global Exploration spacecraft. Using a simple assumption for the He+ density at solar maximum based on a statistical study, we found ?O+ values ranging from near zero to close to unity. For geostationary spacecraft that corotate with the Earth, sudden changes in density for both ?m and ne often appear between dusk and midnight magnetic local time, especially when Kp is significantly above zero. This probably indicates that the bulk (total) ions have energy below a few keV and that the satellites are crossing from closed or previously closed to open drift paths. During long periods that are geomagnetically quiet, the mass density varies little, but ne gradually refills leading to a gradual change in composition from low-density plasma that is relatively cold and heavy (high-average ion mass M ? ?m/ne) to high-density plasma that is relatively cold and light (low M) plasmasphere-like plasma. During active periods we observe a similar daily oscillation in plasma properties from the dayside to the nightside, with cold and light high-density plasma (more plasmasphere-like) on the dayside and hotter and more heavy low-density plasma (more plasma sheet-like) on the nightside. The value of ne is very dependent on whether it is measured inside or outside a plasmaspheric plume, while ?m is not. All of our results were found at solar maximum; previous results suggest that there will be much less O+ at solar minimum under all conditions.

  18. THE ORBITS OF NEPTUNE'S OUTER SATELLITES

    SciTech Connect

    Brozovic, Marina; Jacobson, Robert A.; Sheppard, Scott S. E-mail: raj@jpl.nasa.gov

    2011-04-15

    In 2009, we used the Subaru telescope to observe all the faint irregular satellites of Neptune for the first time since 2004. These observations extend the data arcs for Halimede, Psamathe, Sao, Laomedeia, and Neso from a few years to nearly a decade. We also report on a search for unknown Neptune satellites in a half-square degree of sky and a limiting magnitude of 26.2 in the R band. No new satellites of Neptune were found. We numerically integrate the orbits for the five irregulars and summarize the results of the orbital fits in terms of the state vectors, post-fit residuals, and mean orbital elements. Sao and Neso are confirmed to be Kozai librators, while Psamathe is a 'reverse circulator'. Halimede and Laomedeia do not seem to experience any strong resonant effects.

  19. Satellite orbit determination and gravity field recovery from satellite-to-satellite tracking

    NASA Astrophysics Data System (ADS)

    Wakker, K. F.; Ambrosius, B. A. C.; Leenman, H.

    1989-07-01

    Studies on satellite-to-satellite tracking (SST) with POPSAT (a geodetic satellite concept) and a ERS-class (Earth observation) satellite, a Satellite-to-Satellite Tracking (SST) gravity mission, and precise gravity field determination methods and mission requirements are reported. The first two studies primarily address the application of SST between the high altitude POPSAT and an ERS-class or GRM (Geopotential Research Mission) satellite to the orbit determination of the latter two satellites. Activities focussed on the determination of the tracking coverage of the lower altitude satellite by ground based tracking systems and by POPSAT, orbit determination error analysis and the determination of the surface forces acting on GRM. The third study surveys principles of SST, uncertainties of existing drag models, effects of direct luni-solar attraction and tides on orbit and the gravity gradient observable. Detailed ARISTOTELES (which replaced POPSAT) orbit determination error analyses were performed for various ground based tracking networks.

  20. Patterns of fire activity over Indonesia and Malaysia from polar and geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Hyer, Edward J.; Reid, Jeffrey S.; Prins, Elaine M.; Hoffman, Jay P.; Schmidt, Christopher C.; Miettinen, Jukka I.; Giglio, Louis

    2013-03-01

    Biomass burning patterns over the Maritime Continent of Southeast Asia are examined using a new active fire detection product based on application of the Wildfire Automated Biomass Burning Algorithm (WF_ABBA) to data from the imagers on the MTSAT geostationary satellites operated by the Japanese space agency JAXA. Data from MTSAT-1R and MTSAT-2 covering 34 months from September 2008 to July 2011 are examined for a study region consisting of Indonesia, Malaysia, and nearby environs. The spatial and temporal distributions of fires detected in the MTSAT WF_ABBA product are described and compared with active fire observations from MODIS MOD14 data. Land cover distributions for the two instruments are examined using a new 250 m land cover product from the National University of Singapore. The two products show broadly similar patterns of fire activity, land cover distribution of fires, and pixel fire radiative power (FRP). However, the MTSAT WF_ABBA data differ from MOD14 in important ways. Relative to MODIS, the MTSAT WF_ABBA product has lower overall detection efficiency, but more fires detected due to more frequent looks, a greater relative fraction of fires in forest and a lower relative fraction of fires in open areas, and significantly higher single-pixel retrieved FRP. The differences in land cover distribution and FRP between the MTSAT and MODIS products are shown to be qualitatively consistent with expectations based on pixel size and diurnal sampling. The MTSAT WF_ABBA data are used to calculate coverage-corrected diurnal cycles of fire for different regions within the study area. These diurnal cycles are preliminary but demonstrate that the fraction of diurnal fire activity sampled by the two MODIS sensors varies significantly by region and vegetation type. Based on the results from comparison of the two fire products, a series of steps is outlined to account for some of the systematic biases in each of these satellite products in order to produce a successful merged fire detection product.

  1. 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 (60N - 60S) IR Dataset, is one of TRMM ancillary datasets. They are globally-merged (60N-60S) 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 (60N-60S) 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.

  2. 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.

  3. History of on-orbit satellite fragmentations

    NASA Technical Reports Server (NTRS)

    Nauer, David J.

    1992-01-01

    Since the first serious satellite fragmentation occurred in Jun. 1961, and instantaneously increased the total Earth satellite population by more than 400 percent, 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 1970's and the marked increase in the number of fragmentations in the 1980's served to widen international research into the characteristics and consequences of such events. Plans for large, manned space stations in the next decade and beyond demand a better understanding of the hazards of the dynamic Earth satellite population. The contribution of satellite fragmentations to the growth of the Earth satellite population is complex and varied. The majority of detectable fragmentation debris have already fallen out of orbit, and the effects of 40 percent of all fragmentations have completely disappeared. In this volume, satellite fragmentations are categorized by their assessed nature and to a lesser degree by their effect on the near-Earth space environment. A satellite breakup is the usually destructive disassociation of an orbital payload, rocket body, or structure, often with a wide range of ejecta velocities. A satellite breakup may be accidental or the result of intentional actions, e.g., due to a propulsion system malfunction or a space weapons test, respectively. An anomalous event is the unplanned separation, usually at low velocity, of one or more detectable objects from a satellite which remains essentially intact. Anomalous events can be caused by material deterioration of items such as thermal blankets, protective shields, or solar panels. As a general rule, a satellite breakup will produce considerably more debris, both trackable and non-trackable, than an anomalous event. From one perspective, satellite breakups may be viewed as a measure of the effects of man's activity on the environment, while anomalous events may be a measure of the environment on man-made objects.

  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 Garca-Haro, F.J., F. Camacho-de Coca, J. Meli, B. Martnez (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. Visible infrared spin-scan radiometers (VISSR) for the Geostationary Operational Environmental Satellite (GOES) B and C application

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Two visible infrared spin scan radiometer (VISSR) instruments provided for the Geostationary Operational Environmental Satellite B and C (GOES B and C) spacecrafts are described. The instruments are identical to those supplied previously are summarized. A significant number of changes primarily involving corrections of drawing errors and omissions were also performed. All electrical changes were breadboarded (where complexity required this), were incorporated into the test module, and subjected to verification of proper operation throughout fall instrument temperature range. Evaluation of the changes also included design operating safety margins to account for component variations and life.

  7. Dual RF Astrodynamic GPS Orbital Navigator Satellite

    NASA Technical Reports Server (NTRS)

    Kanipe, David B.; Provence, Robert Steve; Straube, Timothy M.; Reed, Helen; Bishop, Robert; Lightsey, Glenn

    2009-01-01

    Dual RF Astrodynamic GPS Orbital Navigator Satellite (DRAGONSat) will demonstrate autonomous rendezvous and docking (ARD) in low Earth orbit (LEO) and gather flight data with a global positioning system (GPS) receiver strictly designed for space applications. ARD is the capability of two independent spacecraft to rendezvous in orbit and dock without crew intervention. DRAGONSat consists of two picosatellites (one built by the University of Texas and one built by Texas A and M University) and the Space Shuttle Payload Launcher (SSPL); this project will ultimately demonstrate ARD in LEO.

  8. Low Earth Orbit satellite traffic simulator

    NASA Technical Reports Server (NTRS)

    Hoelzel, John

    1995-01-01

    This paper describes a significant tool for Low Earth Orbit (LEO) capacity analysis, needed to support marketing, economic, and design analysis, known as a Satellite Traffic Simulator (STS). LEO satellites typically use multiple beams to help achieve the desired communication capacity, but the traffic demand in these beams in usually not uniform. Simulations of dynamic, average, and peak expected demand per beam is a very critical part of the marketing, economic, and design analysis necessary to field a viable LEO system. An STS is described in this paper which can simulate voice, data and FAX traffic carried by LEO satellite beams and Earth Station Gateways. It is applicable world-wide for any LEO satellite constellations operating over any regions. For aeronautical applications to LEO satellites. the anticipates aeronautical traffic (Erlangs for each hour of the day to be simulated) is prepared for geographically defined 'area targets' (each major operational region for the respective aircraft), and used as input to the STS. The STS was designed by Constellations Communications Inc. (CCI) and E-Systems for usage in Brazil in accordance with an ESCA/INPE Statement Of Work, and developed by Analytical Graphics Inc. (AGI) to execute on top of its Satellite Tool Kit (STK) commercial software. The STS simulates constellations of LEO satellite orbits, with input of traffic intensity (Erlangs) for each hour of the day generated from area targets (such as Brazilian States). accumulated in custom LEO satellite beams, and then accumulated in Earth Station Gateways. The STS is a very general simulator which can accommodate: many forms of orbital element and Walker Constellation input; simple beams or any user defined custom beams; and any location of Gateways. The paper describes some of these features, including Manual Mode dynamic graphical display of communication links, to illustrate which Gateway links are accessible and which links are not, at each 'step' of the satellite orbit. In the two Performance Modes, either Channel capacity or Grade Of Service (GOS) for objects (Satellite beams, Gateways, and an entire satellite) are computed respectively by standard traffic table capacity lookup and blocking probability equations. GOS can be input, with number of channels calculated, or number of channels can be input, with GOS calculated. Also described are some of the STS Test Procedure approach and results. AGI plans to make the STS features available through their normal commercial STK products. E-Systems is a co-developer, tester, and user of the STS. The Test Procedure for the STS was prepared by E-Systems, as an independent tester for CCI, to support the CCI delivery of the STS to ESCA, for their customer INPE.

  9. Investigation of biomass burning and aerosol loading and transport in South America utilizing geostationary satellites

    NASA Technical Reports Server (NTRS)

    Menzel, Paul; Prins, Elaine

    1995-01-01

    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, we 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). To date, our efforts have focused on GOES-7 and GOES-8 ABBA development, algorithm development for aerosol monitoring, data acquisition and archiving, and participation in the SCAR-C and SCAR-B field programs which have provided valuable information for algorithm testing and validation. Implementation of the initial version of the GEOS-8 ABBA on case studies in North, Central, and South America has demonstrated the improved capability for monitoring diurnal fire activity and smoke/aerosol transport with the GOES-8 throughout the Western Hemisphere.

  10. 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.

  11. 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.

  12. Orbit-spectrum sharing between the fixed-satellite and broadcasting-satellite services with applications to 12 GHz domestic systems

    NASA Technical Reports Server (NTRS)

    Reinhart, E. E.

    1974-01-01

    A systematic, tutorial analysis of the general problem of orbit-spectrum sharing among inhomogeneous satellite system is presented. Emphasis is placed on extrapolating and applying the available data on rain attenuation and on reconciling differences in the results of various measurements of the subjective effects of interference on television picture quality. An analytic method is presented for determining the approximate values of the intersatellite spacings required to keep mutual interference levels within prescribed limits when many dissimilar satellites share the orbit. A computer model was developed for assessing the interference compatibility of arbitrary configurations of large numbers of geostationary satellite systems. It is concluded that the band from 11.7 c GHz can be shared effectively by broadcasting-satellite and fixed-satellite systems. Recommendations for future study are included.

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

    NASA Astrophysics Data System (ADS)

    Chaudhary, Kalpana; Vishvakarma, Babau R.

    2010-11-01

    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 power; received energy over a year and weight of the rectenna array for the same beam intensity showed varied results for Molniya orbit based SSPS, LEO based SSPS and GEO based SSPS. The power delivered by the LEO SSPS was highest which indicated that this SSPS may be efficient for the short term power requirement. However, it is observed from the results of the energy received over a year that the GEO based system is suitable for base load power plant as it is capable of delivering constant energy through out a year. Further, the weight of the rectenna and hence the space required for ground station for same power output is smallest for Molniya orbit based system for a range of rectenna array radius considered. It is thus envisaged that the Molniya orbit based system would be a better choice for commercial use of SSPS. These findings may help for judicious selection of satellite orbit and ground station location for placing the satellite for SSPS for various applications.

  14. Ionospheric Pc5 plasma oscillations observed by the King Salmon HF radar and their comparison with geomagnetic pulsations on the ground and in geostationary orbit

    NASA Astrophysics Data System (ADS)

    Sakaguchi, K.; Nagatsuma, T.; Ogawa, T.; Obara, T.; Troshichev, O. A.

    2012-03-01

    We analyzed Pc5 (1.7-6.7 mHz) oscillations of ionospheric Doppler plasma velocity observed on a westward pointing beam 3 of the SuperDARN King Salmon HF radar in Alaska during the solar maximum in 2002 and the minimum in 2007. Local time distributions of the ionospheric Pc5 oscillations showed peculiar asymmetric characteristics in both years; that is, the occurrence probability had a maximum around the magnetic midnight, whereas backscatter echoes exhibited almost no oscillation on the dayside. We compared these ionospheric Pc5 events with magnetic field variations on the ground under the radar beam at Pebek and King Salmon and the geostationary ETS-8 satellite at almost conjugate longitude. We found only a few nightside events where both the radar and magnetometers detected similar sinusoidal oscillations. On the other hand, from statistical spectral analyses we found that there were positive correlations between the integrated Pc5 range spectral power of velocity oscillations and the geomagnetic pulsations both on the ground and in geostationary orbit although the pulsation powers were quite low. For these ionospheric Pc5 events, we found that both solar wind bulk flow speed and dynamic pressure showed no correlation with the spectral power and more than half of the Pc5 events were observed when the geomagnetic activities were low as inferred from the AE and Dst indices. These results indicate that the azimuthal Pc5 oscillation in the ionospheric plasma flow does not represent well-known characteristics of Pc5 pulsations driven by solar wind changes. We consider that the nightside occurrence peak of the ionospheric Pc5 oscillation might be related to diurnal changes in the ionospheric conductivity, which controls the amplitude of wave electric fields in the ionosphere. Therefore, the Pc5 wave power distributions obtained by radar observations provide features different from those obtained from magnetic field observations.

  15. 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.

  16. The Near-Earth Orbit Surveillance Satellite

    NASA Astrophysics Data System (ADS)

    Wallace, Brad; Scott, Robert (Lauchie); Bedard, Donald; Matthews, Jaymie; Grocott, Simon

    2006-06-01

    Defence Research and Development Canada (DRDC) and the Canadian Space Agency (CSA) are jointly working to place a microsatellite, equipped with a small optical telescope, on orbit to detect and track both "deep-space" earth orbiting objects (orbital altitudes > 5000 km), and inner-earth orbit (IEO) asteroids. The satellite will be named the Near Earth Orbit Surveillance Satellite (NEOSSat), is baselined for launch in 4 th Q 2008, and will be equipped with a 15cm diameter telescope capable of detecting 19.5 th magnitude stars over a 100s integration. Other important design requirements of this telescope include the ability to observe to within 45 degrees of the sun (to better detect IEO asteroids) and the ability to observe to within 20 degrees of the anti-sun direction and remain power-positive. The mission is expected to cost $11M CDN (launch costs included, but operating and ground-station costs excluded). The scientific aims of the NEOSSat mission will be described and the results of the NEOSSat Phase-A will be presented. Test observations have been conducted using the MOST ("Microvariability and Oscillations of STars") microsatellite, the inspiration for NEOSSat, and the results of these observations will be shown here; these tests validate both the general concept of using a microsatellite for these types of observations, as well as the expected performance.

  17. 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.

  18. Orbital positioning of domestic satellites. [area coverage and radio frequency interference optimization

    NASA Technical Reports Server (NTRS)

    Gubin, S.; Kane, D.

    1973-01-01

    An important factor in establishing domestic or regional communication satellite systems which share a given frequency band is the positioning of the satellites in the arc of the geostationary orbit that is visible to the area to be served. A description is given of the results of orbit spacing studies performed with respect to the eight different space systems proposed to provide U.S. domestic communication services. Some tentative guidelines which may be of general use are proposed. Four sets of computer models were studied, taking into account quasi-homogeneous models, a five-system model, a heterogeneous model with 3-degree spacings, and a heterogeneous model with unequal spacings and with coordination.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2004-11-01

    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 profiles with higher accuracy and vertical resolution than obtained through current sounder technologies. HES will provide measurements of the properties of the shelf and coastal waters and back up imaging (at in-situ resolution) for the GOES-R Advanced Baseline Imager (ABI). The HES team is forging the future of remote environmental monitoring with the development of an operational instrument with high temporal, spatial and spectral-resolution and broad hemispheric coverage. The HES development vision includes threshold and goal requirements that encompass potential system solutions. The HES team has defined tasks for the instrument(s) that include a threshold functional complement of Disk Sounding (DS), Severe Weather/Mesoscale Sounding (SW/M), and Shelf and Coastal Waters imaging (CW) and a goal functional complement of Open Ocean (OO) imaging, and back up imaging (at in-situ resolution) for the GOES-R Advanced Baseline Imager (ABI). To achieve the best-value procurement, the GOES-R Project has base-lined a two-phase procurement approach to the HES design and development; a Formulation/study phase and an instrument Implementation phase. During Formulation, currently slated for the FY04-05 timeframe, the developing team(s) will perform Systems Requirements Analysis and evaluation, System Trade and Requirements Baseline Studies, Risk Assessment and Mitigation Strategy and complete a Preliminary Conceptual Design of the HES instrument. The results of the formulation phase will be leveraged to achieve an effective and efficient system solution during the Implementation Phase scheduled to begin FY05 for a resultant FY12 launch. The magnitude of complexity of the HES development requires an appreciation of the technologies required to achieve the functional objectives. To this end, the GOES-R project team is making available all NASA developed technologies to potential HES vendors, including, the NASA New Millennium Program"s (NMP) Earth Observing-3, Geostationary Imaging Fourier Transform Spectrometer (GIFTS) instrument developed technologies, as applicable. It is anticipated that the instrument(s) meeting the HES requirements will be either a dispersive spectrometer or an interferometric spectrometer or perhaps a combination. No instrument configuration is preferred or favored by the Government. This paper outlines the HES development plan; including an overview of current requirements, existing partnerships and the GOES-R project methodologies to achieve the advanced functional objectives of the GOES Program partnership.

  1. Improvement of Aerosol Optical Depth Retrieval over Hong Kong from a Geostationary Meteorological Satellite Using Critical Reflectance with Background Optical Depth Correction

    NASA Technical Reports Server (NTRS)

    Kim, Mijin; Kim, Jhoon; Wong, Man Sing; Yoon, Jongmin; Lee, Jaehwa; Wu, Dong L.; Chan, P.W.; Nichol, Janet E.; Chung, Chu-Yong; Ou, Mi-Lim

    2014-01-01

    Despite continuous efforts to retrieve aerosol optical depth (AOD) using a conventional 5-channelmeteorological imager in geostationary orbit, the accuracy in urban areas has been poorer than other areas primarily due to complex urban surface properties and mixed aerosol types from different emission sources. The two largest error sources in aerosol retrieval have been aerosol type selection and surface reflectance. In selecting the aerosol type from a single visible channel, the season-dependent aerosol optical properties were adopted from longterm measurements of Aerosol Robotic Network (AERONET) sun-photometers. With the aerosol optical properties obtained fromthe AERONET inversion data, look-up tableswere calculated by using a radiative transfer code: the Second Simulation of the Satellite Signal in the Solar Spectrum (6S). Surface reflectance was estimated using the clear sky composite method, awidely used technique for geostationary retrievals. Over East Asia, the AOD retrieved from the Meteorological Imager showed good agreement, although the values were affected by cloud contamination errors. However, the conventional retrieval of the AOD over Hong Kong was largely underestimated due to the lack of information on the aerosol type and surface properties. To detect spatial and temporal variation of aerosol type over the area, the critical reflectance method, a technique to retrieve single scattering albedo (SSA), was applied. Additionally, the background aerosol effect was corrected to improve the accuracy of the surface reflectance over Hong Kong. The AOD retrieved froma modified algorithmwas compared to the collocated data measured by AERONET in Hong Kong. The comparison showed that the new aerosol type selection using the critical reflectance and the corrected surface reflectance significantly improved the accuracy of AODs in Hong Kong areas,with a correlation coefficient increase from0.65 to 0.76 and a regression line change from tMI [basic algorithm] = 0.41tAERONET + 0.16 to tMI [new algorithm] = 0.70tAERONET + 0.01.

  2. 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

  3. Long-term analysis of clear sky at astronomical sites: a comparison between polar and geostationary satellites

    NASA Astrophysics Data System (ADS)

    Cavazzani, S.; Zitelli, V.; Ortolani, S.

    2015-09-01

    In this paper, we analyse three sites of great astronomical importance: Mt Graham, Paranal and La Silla. In recent years, with the development of new telescopes, the study of cloud cover is getting more and more important for the selection of new sites as well as for the development of existing telescopes. At the moment there is discussion on the techniques used to study climatic conditions. We have mainly two large data sets: satellite data and ground data. The two sets have advantages and disadvantages. We study in detail the various data available and we compare these data and analyse the correlations between them. In particular, we focus on the long-term statistics for the trends in climate change. We use two satellites: GOES (Geostationary Operational Environmental Satellite) and Aqua. In particular, we use the GOES camera data and MODIS (Moderate Resolution Imaging Spectroradiometer) data, which is a key instrument aboard the Aqua satellite. Finally, we use the heliograph ground data of the Columbine weather station to validate the two families of satellite data. The use of such data allows a mutual validation of the results, which allows the analysis to be extended to other sites. We obtained a mean night cloud cover for the 10 yr analysed (2003-2012) of 12 per cent at Paranal, 22 per cent at La Silla and 37 per cent at Mt Graham. We also get a punctual correlation of 96 per cent between the two satellites and of 92 per cent between the satellite and the heliograph data at Mt Graham for 2009.

  4. ESTIMATE OF SOLAR MAXIMUM USING THE 1-8 Å GEOSTATIONARY OPERATIONAL ENVIRONMENTAL SATELLITES X-RAY MEASUREMENTS

    SciTech Connect

    Winter, L. M.; Balasubramaniam, K. S.

    2014-10-01

    We present an alternate method of determining the progression of the solar cycle through an analysis of the solar X-ray background. Our results are based on the NOAA Geostationary Operational Environmental Satellites (GOES) X-ray data in the 1-8 Å band from 1986 to the present, covering solar cycles 22, 23, and 24. The X-ray background level tracks the progression of the solar cycle through its maximum and minimum. Using the X-ray data, we can therefore make estimates of the solar cycle progression and the date of solar maximum. Based upon our analysis, we conclude that the Sun reached its hemisphere-averaged maximum in solar cycle 24 in late 2013. This is within six months of the NOAA prediction of a maximum in spring 2013.

  5. Orbit determination and time synchronization for a GEO/IGSO satellite navigation constellation with regional tracking network

    NASA Astrophysics Data System (ADS)

    Zhou, ShanShi; Hu, XiaoGong; Wu, Bin; Liu, Li; Qu, WeiJing; Guo, Rui; He, Feng; Cao, YueLing; Wu, XiaoLi; Zhu, LingFeng; Shi, Xin; Tan, HongLi

    2011-06-01

    Aiming at regional services, the space segment of COMPASS (Phase I) satellite navigation system is a constellation of Geostationary Earth Orbit (GEO), Inclined Geostationary Earth Orbit (IGSO) and Medium Earth Orbit (MEO) satellites. Precise orbit determination (POD) for the satellites is limited by the geographic distribution of regional tracking stations. Independent time synchronization (TS) system is developed to supplement the regional tracking network, and satellite clock errors and orbit data may be obtained by simultaneously processing both tracking data and TS data. Consequently, inconsistency between tracking system and TS system caused by remaining instrumental errors not calibrated may decrease navigation accuracy. On the other hand, POD for the mixed constellation of GEO/IGSO/MEO with the regional tracking network leads to parameter estimations that are highly correlated. Notorious example of correlation is found between GEO's orbital elements and its clock errors. We estimate orbital elements and clock errors for a 3GEO+2IGSO constellation in this study using a multi-satellite precise orbit determination (MPOD) strategy, with which clock error elimination algorithm is applied to separate orbital and clock estimates to improve numerical efficiency. Satellite Laser Ranging (SLR) data are used to evaluate User Ranging Error (URE), which is the orbital error projected on a receiver's line-of-sight direction. Two-way radio-wave time transfer measurements are used to evaluate clock errors. Experimenting with data from the regional tracking network, we conclude that the fitting of code data is better than 1 m in terms of Root-Mean-Square (RMS), and fitting of carrier phase is better than 1 cm. For orbital evaluation, difference between computed receiver-satellite ranging based on estimated orbits and SLR measurements is better than 1 m (RMS). For clock estimates evaluation, 2-hour linear-fitting shows that the satellite clock rates are about 1.E-10 s/s, while receiver clock rates are about 110-13-110-12 s/s. For the 72-hour POD experiment, the average differences between POD satellite clock rates estimates and clock measurements based on TS system are about 110-13 s/s, and for receiver clock rates, the differences are about 110-15 s/s.

  6. COSPAS-SARSAT Satellite Orbit Predictor. Volume 3

    NASA Technical Reports Server (NTRS)

    Friedman, Morton L.; Garrett, James

    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.

  7. 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.

  8. Cost competitive space transportation system for geostationary payloads

    NASA Technical Reports Server (NTRS)

    Jones, C. R.

    1976-01-01

    A geostationary satellite system designer will have a number of launch vehicles to consider in the system designs for the 1980s. The Space transportation System (the shuttle orbiter plus upper stage) offers the opportunity for lower system cost in comparison with the expendable launch vehicles. An analysis of a spin stabilized solid rocket motor stage has demonstrated the feasibility of this upper stage concept. A cost competitive Space Transportation System (STS) for geostationary payloads is made possible by achievement of the STS cost goals, multiple launch from the STS orbiter, and a user-provided spin stabilized upper stage.

  9. Monthly mean large-scale analyses of upper-tropospheric humidity and wind field divergence derived from three geostationary satellites

    NASA Technical Reports Server (NTRS)

    Schmetz, Johannes; Menzel, W. Paul; Velden, Christopher; Wu, Xiangqian; Vandeberg, Leo; Nieman, Steve; Hayden, Christopher; Holmlund, Kenneth; Geijo, Carlos

    1995-01-01

    This paper describes the results from a collaborative study between the European Space Operations Center, the European Organization for the Exploitation of Meteorological Satellites, the National Oceanic and Atmospheric Administration, and the Cooperative Institute for Meteorological Satellite Studies investigating the relationship between satellite-derived monthly mean fields of wind and humidity in the upper troposphere for March 1994. Three geostationary meteorological satellites GOES-7, Meteosat-3, and Meteosat-5 are used to cover an area from roughly 160 deg W to 50 deg E. The wind fields are derived from tracking features in successive images of upper-tropospheric water vapor (WV) as depicted in the 6.5-micron absorption band. The upper-tropospheric relative humidity (UTH) is inferred from measured water vapor radiances with a physical retrieval scheme based on radiative forward calculations. Quantitative information on large-scale circulation patterns in the upper-troposphere is possible with the dense spatial coverage of the WV wind vectors. The monthly mean wind field is used to estimate the large-scale divergence; values range between about-5 x 10(exp -6) and 5 x 10(exp 6)/s when averaged over a scale length of about 1000-2000 km. The spatial patterns of the UTH field and the divergence of the wind field closely resemble one another, suggesting that UTH patterns are principally determined by the large-scale circulation. Since the upper-tropospheric humidity absorbs upwelling radiation from lower-tropospheric levels and therefore contributes significantly to the atmospheric greenhouse effect, this work implies that studies on the climate relevance of water vapor should include three-dimensional modeling of the atmospheric dynamics. The fields of UTH and WV winds are useful parameters for a climate-monitoring system based on satellite data. The results from this 1-month analysis suggest the desirability of further GOES and Meteosat studies to characterize the changes in the upper-tropospheric moisture sources and sinks over the past decade.

  10. 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.

  11. Hill equations for satellite orbit determination

    NASA Astrophysics Data System (ADS)

    Vancoevorden, R. G.

    1992-11-01

    Equations of motion using a periodical circular orbit are addressed. The orbital perturbations are given with respect to this moving triad. This set of equations, called the Hill equations, exists of three second order linear differential equations. They describe the problem in a first order approximation. Depending on the type of the disturbing forces, there exist different solutions of these equations. When there are no disturbing forces, the equations are called the homogeneous Hill equations, and only the initial values of the state vector can change the shape of the orbit. Disturbing forces which are more complex, can be transformed into Fourier series and then used in the equations to get an exact analytical solution of the approximated problem. By looking at the complete solution of the Hill equations, it can be seen that there are a few cases in which the solutions are not valid. The so called critical frequencies give a resonant effect on the orbital perturbations. These frequencies are the zero frequency and the once per revolution frequency. Resonant sources are for instance: drag, solar pressure, etc. A simple rendezvous problem, which describes the use of the homogeneous equations of motion, is discussed, some resonant sources are explained, and two examples of some relativistic effects are given. The cases in which the disturbing frequency is almost equal to a critical frequency are described. The amplitudes of the perturbations can grow very big in these so called near resonance cases. As a result of this work, the Hill equations can be said to be very good for educative purposes, because they give a very good view on the effects of disturbing forces on the orbit of a satellite. It should always be kept in mind that many simplifications are made when deriving the Hill equations.

  12. NASA-Langley Web-Based Operational Real-time Cloud Retrieval Products from Geostationary Satellites

    NASA Technical Reports Server (NTRS)

    Palikonda, Rabindra; Minnis, Patrick; Spangenberg, Douglas A.; Khaiyer, Mandana M.; Nordeen, Michele L.; Ayers, Jeffrey K.; Nguyen, Louis; Yi, Yuhong; Chan, P. K.; Trepte, Qing Z.; Chang, Fu-Lung; Smith, William L, Jr.

    2006-01-01

    At NASA Langley Research Center (LaRC), radiances from multiple satellites are analyzed in near real-time to produce cloud products over many regions on the globe. These data are valuable for many applications such as diagnosing aircraft icing conditions and model validation and assimilation. This paper presents an overview of the multiple products available, summarizes the content of the online database, and details web-based satellite browsers and tools to access satellite imagery and products.

  13. 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.

  14. Aqua satellite orbiting the Earth - Duration: 116 seconds.

    NASA Video Gallery

    This animation shows the Aqua satellite orbiting the Earth on August 27, 2005 by revealing MODIS true-color imagery for that day. This animation is on a cartesian map projection, so the satellite w...

  15. Orbital elements of Saturn's F ring and its shepherding satellites

    NASA Technical Reports Server (NTRS)

    Synnott, S. P.

    1982-01-01

    The orbital parameters of Saturn's F-ring and the shepherding satellites were estimated from Voyager images. The method, results and associated uncertainties are described. Braids were observed in a few frames near shepherd satellite conjunctions.

  16. Contraction of high eccentricity satellite orbits using KS elements in an oblate atmosphere

    NASA Astrophysics Data System (ADS)

    Sharma, Ram Krishan

    1999-01-01

    A non-singular analytical theory for the contraction of high eccentricity orbits (eccentricity e > 0.5) under the influence of air drag is developed in terms of the KS elements, using an oblate exponential atmospheric model. With the help of MACSYMA software, the series expansions include up to the sixth power in terms of an independent variable ?, introduced by Sterne as cos E = 1 - H ?2 / a e, where E and a are the eccentric anomaly and semi-major axis of the orbit and H, the density scale height, is assumed constant. The solution is tested numerically over a wide range of orbital parameters: perigee height (Hp), e and inclination (i) up to 100 revolutions and is found to be quite accurate. The % error in the semi-major axis computation when compared with numerically integrated values, for test cases whose perigee heights vary from 150 to 300 km and eccentricities increase from 0.6 to 0.8, is found to be less than one. The decay rates of a and e are found to be lower than those obtained with spherically symmetrical atmospheric models and increasing with increase in inclination. The theory can be effectively used for the orbital decay of Molniya type of communication satellites, decay of geostationary transfer orbits and during mission planning of aeroassisted orbital transfer orbits.

  17. Climatological assessment of desert targets over East Asia — Australian region for the solar channel calibration of geostationary satellites

    NASA Astrophysics Data System (ADS)

    Chun, Hyoung-Wook; Sohn, B. J.

    2014-02-01

    Desert targets for solar channel calibration of geostationary satellites in the East Asia — Australian region were selected and their qualities were assessed with aid of Moderate Resolution Imaging Spectroradiometer data (i.e., white-sky surface albedo, aerosol optical thickness, and cloud fraction) from 2002 to 2008. The magnitude, spatial uniformity, and temporal stability of the white-sky surface albedo are examined in order to select bright and stable targets. Subsequently those selected targets over China, India, and Australia are further checked for their qualities in terms of data yielding ratio, aerosol optical thickness, cloud fraction, satellite viewing angle, and solar zenith angle. Results indicate that Chinese targets are found to be not adequate as calibration targets in spite of excellent surface conditions because of high percentage of cloud, possibly heavy aerosol loading, and lower solar elevation angle in particular during winter time. Indian site should be take care about relatively high temporal variation of surface condition and heavy aerosol loading. On the other hand, Australian desert targets are considered to be best when surface brightness, spatial and temporal stability, data yielding ratio, aerosol, and cloud are counted.

  18. In-orbit measurement of the SBS satellite

    NASA Astrophysics Data System (ADS)

    Emmert, C.; Riginos, V.; Potukuchi, J.

    Satellite Business Systems (SBS) launched the first of a series of 14/12-GHz communications satellites in November 1980. In-orbit tests were accomplished to ensure that the communications subsystem in the spacecraft had successfully survived the launch into synchronous orbit. These tests were performed using SBS Tracking, Telemetry and Command (TT&C) facilities equipped for this and other related monitoring functions. This paper briefly discusses the SBS satellites, in-orbit measurement procedures with typical test results, and continued in-orbit monitoring performed during the life of the satellite.

  19. Effects of the Forecasting Methods, Precipitation Character, and Satellite Resolution on the Predictability of Short-Term Quantitative Precipitation Nowcasting (QPN) from a Geostationary Satellite

    PubMed Central

    Liu, Yu; Xi, Du-Gang; Li, Zhao-Liang; Ji, Wei

    2015-01-01

    The prediction of the short-term quantitative precipitation nowcasting (QPN) from consecutive gestational satellite images has important implications for hydro-meteorological modeling and forecasting. However, the systematic analysis of the predictability of QPN is limited. The objective of this study is to evaluate effects of the forecasting model, precipitation character, and satellite resolution on the predictability of QPN usingimages of a Chinese geostationary meteorological satellite Fengyun-2F (FY-2F) which covered all intensive observation since its launch despite of only a total of approximately 10 days. In the first step, three methods were compared to evaluate the performance of the QPN methods: a pixel-based QPN using the maximum correlation method (PMC); the Horn-Schunck optical-flow scheme (PHS); and the Pyramid Lucas-Kanade Optical Flow method (PPLK), which is newly proposed here. Subsequently, the effect of the precipitation systems was indicated by 2338 imageries of 8 precipitation periods. Then, the resolution dependence was demonstrated by analyzing the QPN with six spatial resolutions (0.1atial, 0.3a, 0.4atial rand 0.6). The results show that the PPLK improves the predictability of QPN with better performance than the other comparison methods. The predictability of the QPN is significantly determined by the precipitation system, and a coarse spatial resolution of the satellite reduces the predictability of QPN. PMID:26447470

  20. Effects of the Forecasting Methods, Precipitation Character, and Satellite Resolution on the Predictability of Short-Term Quantitative Precipitation Nowcasting (QPN) from a Geostationary Satellite.

    PubMed

    Liu, Yu; Xi, Du-Gang; Li, Zhao-Liang; Ji, Wei

    2015-01-01

    The prediction of the short-term quantitative precipitation nowcasting (QPN) from consecutive gestational satellite images has important implications for hydro-meteorological modeling and forecasting. However, the systematic analysis of the predictability of QPN is limited. The objective of this study is to evaluate effects of the forecasting model, precipitation character, and satellite resolution on the predictability of QPN using images of a Chinese geostationary meteorological satellite Fengyun-2F (FY-2F) which covered all intensive observation since its launch despite of only a total of approximately 10 days. In the first step, three methods were compared to evaluate the performance of the QPN methods: a pixel-based QPN using the maximum correlation method (PMC); the Horn-Schunck optical-flow scheme (PHS); and the Pyramid Lucas-Kanade Optical Flow method (PPLK), which is newly proposed here. Subsequently, the effect of the precipitation systems was indicated by 2338 imageries of 8 precipitation periods. Then, the resolution dependence was demonstrated by analyzing the QPN with six spatial resolutions (0.1atial, 0.3a, 0.4atial rand 0.6). The results show that the PPLK improves the predictability of QPN with better performance than the other comparison methods. The predictability of the QPN is significantly determined by the precipitation system, and a coarse spatial resolution of the satellite reduces the predictability of QPN. PMID:26447470

  1. Lithium-Ion Battery Performance On Board Geostationary And Lunar Orbiter NASA Missions- SDO And LRO

    NASA Astrophysics Data System (ADS)

    Curzon, David; Thwaite, Carl; Buckle, Rachel

    2011-10-01

    ABSLSpace Products have worked together with NASA GSFC to build both the 120Ah LRO and the 150Ah SDO Battery modules. ABSL have used in- house software tools to perform analysis of the battery size to optimize performance. The battery units have been successfully launched into orbit and are meeting all performance requirements. ABSL have also carried out real time life tests based on the simulated mission profile for both projects. ABSL has now correlated the information from the life tests results and the in orbit telemetry data to provide a status of battery health and inputs for system operations and potential for mission extension. This paper provides details of the process applied, and the options available for system optimization.

  2. Rendez-vous and docking in geostationary orbit and other applications

    NASA Astrophysics Data System (ADS)

    Cougnet, C.; Aubertin, J. M.; Govin, B.; Natenbruk, P.

    1982-09-01

    A survey of all orbital phases of the rendezvous and docking (RVD) techniques for GEO is presented, with attention given to hardware interfaces. Results of a simulation of the final approach phase involving six degrees of freedom are discussed. The focus of the paper is the presence of an ESA modular communications spacecraft in GEO as the target, and the delivery and latching of a modular component. The definition and use of RVD systems are noted to be influenced by the location of sensors, the docking ports, and the time of docking. Consideration is given to H- and rosette configurations for the modular platforms, which are passive to the approach of a payload module. Communications between the spacecraft occur within 800 km, with ranging data gathered by the target, sent to the ground for processing, then followed by commands to the payload module. RVD concepts are also useful for LEO and elliptical orbit modular construction.

  3. Observing Tropospheric Chemistry and Climate Variables from Geostationary Orbit With SIRAS-G

    NASA Astrophysics Data System (ADS)

    Johnson, B. R.; Kampe, T. U.

    2005-12-01

    Understanding the impact of pollution on regional, continental, and global scales imposes unique challenges for spaceborne observations. The variability in tropospheric chemistry, source strengths, and transport results in sub-hourly temporal variation, and produces small-scale variations in the vertical and horizontal distribution of trace gases. Current spaceborne observation from low earth orbit have demonstrated the capability to measure tropospheric trace gases from space but are limited to a twice daily observation. Improving the depiction of diurnal variations requires observations from geosynchronous orbit. The Spaceborne Infrared Atmospheric Sounder from Geosynchronous Earth Orbit (SIRAS-G) is being developed under the NASA Instrument Incubator Program to meet this need. SIRAS-G will enable high temporal, spatial, and spectral resolution observations of temperature, water, ozone, aerosol, cloud and surface properties, and important trace gas concentrations such as CO, CH4, N2O and SO2. The spaceborne instrument concept measures thermal emission in 2048 spectral channels over the wavelength range from 3.75 to 15 microns with a nominal resolving power of 1400. The constraints imposed on instrument mass, power and volume by a geosynchronous mission drives the instrument design toward more compact, and less complex optical systems. The system employs a wide field-of-view hyperspectral infrared optical system that splits incoming radiation to four separate grating spectrometer channels. Combined with large 2-D infrared detector arrays, this system provides simultaneous high-resolution spectral and spatial imaging over a large region with a nominal 4x4 km ground resolution. The longer observation times from geosynchronous orbit enable the necessary high signal to noise. However, the longer integration time makes the sensor more sensitive to slowly varying platform motion or mechanical disturbances generated by the instrument or spacecraft subsystems. This leads to a spectral registration problem for imaging filter wheel radiometers or Fourier transform spectrometer. The imaging grating spectrometer, by virtue of its simultaneous collection of spectral information, is significantly less sensitive to disturbances.

  4. 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…

  5. Precise Orbit Determination of Low Earth Satellites at AIUB

    NASA Astrophysics Data System (ADS)

    Jaggi, A.; Bock, H.; Thaller, D.; Dach, R.; Beutler, G.; Prange, L.; Meyer, U.

    2010-12-01

    Many low Earth orbiting (LEO) satellites are nowadays equipped with on-board receivers to collect the observations from Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), or with retro-reflectors for Satellite Laser Ranging (SLR). At the Astronomical Institute of the University of Bern (AIUB) LEO precise orbit determination (POD) using either GPS or SLR data is performed for satellites at very different altitudes. The classical numerical integration techniques used for dynamic orbit determination of LEO satellites at high altitudes are extended by pseudo-stochastic orbit modeling techniques for satellites at low altitudes to efficiently cope with force model deficiencies. Accuracies of a few centimeters are achieved by pseudo-stochastic orbit modeling, e.g., for the Gravity field and steady-state Ocean Circulation Explorer (GOCE).

  6. An initialization procedure for assimilating geostationary satellite data into numerical weather prediction models

    NASA Technical Reports Server (NTRS)

    Gal-Chen, T.; Schmidt, B.; Uccellini, L. W.

    1985-01-01

    An attempt was made to offset the limitations of GEO satellites for supplying timely initialization data for numerical weather prediction models (NWP). The NWP considered combined an isentropic representation of the free atmosphere with a sigma-coordinate model for the lower 200 mb. A flux form of the predictive equations described vertical transport interactions at the boundary of the two model domains, thereby accounting for the poor vertical temperature and wind field resolution of GEO satellite data. A variational analysis approach was employed to insert low resolution satellite-sensed temperature data at varying rates. The model vertical resolution was limited to that available from the satellite. Test simulations demonstrated that accuracy increases with the frequency of data updates, e.g., every 0.5-1 hr. The tests also showed that extensive cloud cover negates the capabilities of IR sensors and that microwave sensors will be needed for temperature estimations for 500-1000 mb levels.

  7. Instrument and Method for Determination of High-Precision Coordinates of Geostationary Artificial Satellites

    NASA Astrophysics Data System (ADS)

    Duma, D. P.; Kizjun, L. N.; Laptienko, N. I.; Melnikov, M. A.; Safronov, Y. I.

    An experiment for determining precise positions of artificial satellites has been carried out at the Main Astronomical Observatory of the Academy of Sciences of the Ukrainian SSR with the help of the Carl-Zeiss double wide-angle astrograph (2 m focal length, 40 cm objective diameter). Estimates of the precision of the satellite position obtained from 9 plates are given. The standard errors are in the range 0.48arcsec - 1.67arcsec.

  8. The Use of the Deep Convective Cloud Technique (DCCT) to Monitor On-Orbit Performance of the Geostationary Lightning Mapper (GLM): Use of Lightning Imaging Sensor (LIS) Data as Proxy

    NASA Technical Reports Server (NTRS)

    Buechler, Dennis E.; Christian, H. J.; Koshak, William J.; Goodman, Steve J.

    2013-01-01

    The Geostationary Lightning Mapper (GLM) on the next generation Geostationary Operational Environmental Satellite-R (GOES-R) will not have onboard calibration capability to monitor its performance. The Lightning Imaging Sensor (LIS) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite has been providing observations of total lightning over the Earth's Tropics since 1997. The GLM design is based on LIS heritage, making it a good proxy dataset. This study examines the performance of LIS throughout its time in orbit. This was accomplished through application of the Deep Convective Cloud Technique (DCCT) (Doelling et al., 2004) to LIS background pixel radiance data. The DCCT identifies deep convective clouds by their cold Infrared (IR) brightness temperatures and using them as invariant targets in the solar reflective portion of the solar spectrum. The GLM and LIS operate in the near-IR at a wavelength of 777.4 nm. In the present study the IR data is obtained from the Visible Infrared Sensor (VIRS) which is collocated with LIS onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. The DCCT is applied to LIS observations for July and August of each year from 1998-2010. The resulting distributions of LIS background DCC pixel radiance for each July August are very similar, indicating stable performance. The mean radiance of the DCCT analysis does not show a long term trend and the maximum deviation of the July August mean radiance for each year is within 0.7% of the overall mean. These results demonstrate that there has been no discernible change in LIS performance throughout its lifetime. A similar approach will used for monitoring the performance of GLM, with cold clouds identified using IR data from the Advanced Baseline Imager (ABI) which will also be located on GOES-R. Since GLM is based on LIS design heritage, the LIS results indicate that GLM should also experience stable performance over its lifetime.

  9. 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 1010 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.

  10. 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.

  11. Satellite orbit and data sampling requirements

    NASA Technical Reports Server (NTRS)

    Rossow, William

    1993-01-01

    Climate forcings and feedbacks vary over a wide range of time and space scales. The operation of non-linear feedbacks can couple variations at widely separated time and space scales and cause climatological phenomena to be intermittent. Consequently, monitoring of global, decadal changes in climate requires global observations that cover the whole range of space-time scales and are continuous over several decades. The sampling of smaller space-time scales must have sufficient statistical accuracy to measure the small changes in the forcings and feedbacks anticipated in the next few decades, while continuity of measurements is crucial for unambiguous interpretation of climate change. Shorter records of monthly and regional (500-1000 km) measurements with similar accuracies can also provide valuable information about climate processes, when 'natural experiments' such as large volcanic eruptions or El Ninos occur. In this section existing satellite datasets and climate model simulations are used to test the satellite orbits and sampling required to achieve accurate measurements of changes in forcings and feedbacks at monthly frequency and 1000 km (regional) scale.

  12. ORBITAL DEPENDENCE OF GALAXY PROPERTIES IN SATELLITE SYSTEMS OF GALAXIES

    SciTech Connect

    Hwang, Ho Seong; Park, Changbom E-mail: cbp@kias.re.k

    2010-09-01

    We study the dependence of satellite galaxy properties on the distance to the host galaxy and the orbital motion (prograde and retrograde orbits) using the Sloan Digital Sky Survey (SDSS) data. From SDSS Data Release 7, we find 3515 isolated satellite systems of galaxies at z < 0.03 that contain 8904 satellite galaxies. Using this sample, we construct a catalog of 635 satellites associated with 215 host galaxies whose spin directions are determined by our inspection of the SDSS color images and/or by spectroscopic observations in the literature. We divide satellite galaxies into prograde and retrograde orbit subsamples depending on their orbital motion with respect to the spin direction of the host. We find that the number of galaxies in prograde orbit is nearly equal to that of retrograde orbit galaxies: the fraction of satellites in prograde orbit is 50% {+-} 2%. The velocity distribution of satellites with respect to their hosts is found to be almost symmetric: the median bulk rotation of satellites is -1 {+-} 8 km s{sup -1}. It is found that the radial distribution of early-type satellites in prograde orbit is strongly concentrated toward the host while that of retrograde ones shows much less concentration. We also find the orbital speed of late-type satellites in prograde orbit increases as the projected distance to the host (R) decreases while the speed decreases for those in retrograde orbit. At R less than 0.1 times the host virial radius (R < 0.1r{sub vir,host}), the orbital speed decreases in both prograde and retrograde orbit cases. Prograde satellites are on average fainter than retrograde satellites for both early and late morphological types. The u - r color becomes redder as R decreases for both prograde and retrograde orbit late-type satellites. The differences between prograde and retrograde orbit satellite galaxies may be attributed to their different origin or the different strength of physical processes that they have experienced through hydrodynamic interactions with their host galaxies.

  13. GPS early-orbit subsystem for earth satellites

    NASA Technical Reports Server (NTRS)

    Laczo, V. T.; Maury, J. L.

    1972-01-01

    The early-orbit capability of the Goddard Trajectory Determination System, which determines starting vectors for earth satellites from angles-only or range-angles observations, is described and documented. Early-orbit results obtained from a variety of satellites, data types and methods of solution are also presented.

  14. Selection of orbits for the CRRES dual mission satellite

    NASA Technical Reports Server (NTRS)

    Frazier, Bill; Stone, Russ; Thompson, Paul

    1986-01-01

    The Combined Release and Radiation Effects Satellite (CRRES) is somewhat unusual, in that it performs related scientific experiments in two very different orbits. The selection of the Low Earth Orbit and Geosynchronous Transfer Orbit requires a number of scientific and engineering trade-offs. Issues in this design process discussed here are launch and insertion capabilities, altitude regimes of scientific interest and orbit stability, ground track and lighting considerations, lifetime of both missions, and the transfer between the two orbits.

  15. 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.

  16. Galilean satellite remote sensing by the Galileo Jupiter Orbiter

    NASA Technical Reports Server (NTRS)

    Yeates, C. M.; Klaasen, K. P.; Clarke, T. C.

    1983-01-01

    The derivation of a mission design strategy for the Galileo Jupiter Orbiter which best satisfies the requirements for remote sensing of the surfaces of the Galilean satellites during a 20-month orbital tour of the Jovian system is described. The celestial mechanics of a spacecraft orbiting about Jupiter and interacting with the Galilean satellites is discussed. A satellite tour strategy designed to optimize the accomplishment of remote sensing, field and particle science, and radio science objectives is developed. Finally, an assessment is made of how well these objectives can be met given the spacecraft, the capabilities of the scientific instruments, and the structure of the satellite tour.

  17. Orbits of the ten small satellites of Uranus

    SciTech Connect

    Owen, W.M. Jr.; Synnott, S.P.

    1987-05-01

    Orbital elements are presented for the ten small satellites discovered by Voyager 2 at Uranus. These ten new satellites, whose provisional IAU designations are 1985UI and 1986UI through 1986U9, lie for the most part in equatorial, circular orbits; the most notable exception is 1986U8, the outer epsilon-ring shepherd, whose eccentricity e = 0.0101. Unlike the Voyager discoveries at Saturn, which included two co-orbiting satellites and three librators, the ten small Uranian satellites all have quite different semimajor axes. 11 references.

  18. Galilean satellite remote sensing by the Galileo Jupiter Orbiter

    NASA Astrophysics Data System (ADS)

    Yeates, C. M.; Klaasen, K. P.; Clarke, T. C.

    The derivation of a mission design strategy for the Galileo Jupiter Orbiter which best satisfies the requirements for remote sensing of the surfaces of the Galilean satellites during a 20-month orbital tour of the Jovian system is described. The celestial mechanics of a spacecraft orbiting about Jupiter and interacting with the Galilean satellites is discussed. A satellite tour strategy designed to optimize the accomplishment of remote sensing, field and particle science, and radio science objectives is developed. Finally, an assessment is made of how well these objectives can be met given the spacecraft, the capabilities of the scientific instruments, and the structure of the satellite tour.

  19. 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.

  20. Use of Geostationary Satellite Data to Force Land Surface Schemes within Atmospheric Mesoscale Models

    NASA Technical Reports Server (NTRS)

    Lapenta, William M.; Suggs, Ron; McNider, Richard T.; Jedlovec, Gary; Dembek, Scott R.; Goodman, H. Michael (Technical Monitor)

    2000-01-01

    A technique has been developed for assimilating GOES-derived skin temperature tendencies and insolation into the surface energy budget equation of a mesoscale model so that the simulated rate of temperature change closely agrees with the satellite observations. A critical assumption of the technique is that the availability of moisture (either from the soil or vegetation) is the least known term in the model's surface energy budget. Therefore, the simulated latent heat flux, which is a function of surface moisture availability, is adjusted based upon differences between the modeled and satellite-observed skin temperature tendencies. An advantage of this technique is that satellite temperature tendencies are assimilated in an energetically consistent manner that avoids energy imbalances and surface stability problems that arise from direct assimilation of surface shelter temperatures. The fact that the rate of change of the satellite skin temperature is used rather than the absolute temperature means that sensor calibration is not as critical. The technique has been employed on a semi-operational basis at the GHCC within the PSU/NCAR MM5. Assimilation has been performed on a grid centered over the Southeastern US since November 1998. Results from the past year show that assimilation of the satellite data reduces both the bias and RMSE for simulations of surface air temperature and relative humidity. These findings are based on comparison of assimilation runs with a control using the simple 5-layer soil model available in MM5. A significant development in the past several months was the inclusion of the detailed Oregon State University land surface model (OSU/LSM) as an option within MM5. One of our working hypotheses has been that the assimilation technique, although simple, may provide better short-term forecasts than a detailed LSM that requires significant number initialized parameters. Preliminary results indicate that the assimilation out performs the OSU/LSM as it is incorporated in MM5. Details will be presented at the symposium.

  1. GEO/SAMS - The Geostationary Synthetic Aperture Microwave Sounder

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn H.

    2008-01-01

    The National Oceanic and Atmospheric Administration (NOAA) has for many years operated two weather satellite systems, the Polar-orbiting Operational Environmental Satellite system (POES), using low-earth orbiting (LEO) satellites, and the Geostationary Operational Environmental Satellite system (GOES), using geostationary earth orbiting (GEO) satellites. (Similar systems are also operated by other nations.) The POES satellites have been equipped with both infrared (IR) and microwave (MW) atmospheric sounders, which makes it possible to determine the vertical distribution of temperature and humidity in the troposphere even under cloudy conditions. Such satellite observations have had a significant impact on weather forecasting accuracy, especially in regions where in situ observations are sparse. In contrast, the GOES satellites have only been equipped with IR sounders, since it has not been feasible to build a large enough antenna to achieve sufficient spatial resolution for a MW sounder in GEO. As a result, GOES soundings can only be obtained in cloud free areas and in the less important upper atmosphere, above the cloud tops. This has hindered the effective use of GOES data in numerical weather prediction. Full sounding capabilities with the GOES system is highly desirable because of the advantageous spatial and temporal coverage that is possible from GEO. While POES satellites provide coverage in relatively narrow swaths, and with a revisit time of 12-24 hours or more, GOES satellites can provide continuous hemispheric coverage, making it possible to monitor highly dynamic phenomena such as hurricanes.

  2. Monitoring objects orbiting earth using satellite-based telescopes

    DOEpatents

    Olivier, Scot S.; Pertica, Alexander J.; Riot, Vincent J.; De Vries, Willem H.; Bauman, Brian J.; Nikolaev, Sergei; Henderson, John R.; Phillion, Donald W.

    2015-06-30

    An ephemeris refinement system includes satellites with imaging devices in earth orbit to make observations of space-based objects ("target objects") and a ground-based controller that controls the scheduling of the satellites to make the observations of the target objects and refines orbital models of the target objects. The ground-based controller determines when the target objects of interest will be near enough to a satellite for that satellite to collect an image of the target object based on an initial orbital model for the target objects. The ground-based controller directs the schedules to be uploaded to the satellites, and the satellites make observations as scheduled and download the observations to the ground-based controller. The ground-based controller then refines the initial orbital models of the target objects based on the locations of the target objects that are derived from the observations.

  3. Numerical simulations of the decay of satellite galaxy orbits

    NASA Technical Reports Server (NTRS)

    Lin, D. N. C.; Tremaine, S.

    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 mass and size and with the number density and mass of halo stars. Significant frictional forces are present even outside the halo, and the orbital decay rate, instead of depending on the procedure used to place the satellite in its orbit, is determined only by the current orbital parameters. This semirestricted N-body method is sufficiently fast to have permitted the running of 200 simulations to date, many more than would have been possible by means of the conventional N-body technique.

  4. An orbit determination from debris impacts on measurement satellites

    NASA Astrophysics Data System (ADS)

    Fujita, Koki; Tasaki, Mitsuhiko; Furumoto, Masahiro; Hanada, Toshiya

    2016-01-01

    This work proposes a method to determine orbital plane of a micron-sized space debris cloud utilizing their impacts on measurement satellites. Given that debris impacts occur on a line of intersection between debris and satellites orbital planes, a couple of debris orbital parameters, right ascension of the ascending node, inclination, and nodal regression rate can be determined by impact times and locations measured from more than two satellites in different earth orbits. This paper proves that unique solution for the debris orbital parameters is obtained from the measurement data, and derives a computational scheme to estimate them. The effectiveness of the proposed scheme is finally demonstrated by a simulation test, in which measurement data are obtained from a numerical simulation considering realistic debris' and satellites' orbits.

  5. A millimeter and sub-millimeter wave frequency selective surface beamsplitter for geostationary orbit microwave radiometers

    NASA Astrophysics Data System (ADS)

    Cui, Guang-Bin; Zhao, Hai-Bo; Zhang, Yong-Fang; Miao, Jun-Gang

    2012-11-01

    We report the design of three frequency selective surface (FSS) filters used on the FengYun-4 (FY-4) microwave satellite, which separate five-frequency bands in the frequency range of 50-429 GHz with the insertion loss less than 0.4 dB, and separation between adjacent channels more than 20 dB for either TE or TM incidence. Firstly, we briefly introduce the disadvantages of two types of FSS filter: waveguide-array FSS and printed FSS, which are commonly employed in the millimeter and sub-millimeter wave band. In order to meet the insertion loss requirement and specified spectral transmission response, we adopt a filter composed of two closely spaced freestanding metal plates, which contains an array of resonant ring slot elements. Computer simulation technology (CST) is used to optimize the structural dimensions of the resonant unit and interlayer separation. Numerical results show that these FSS filters exhibit transmission loss of less than 0.4 dB and separation between adjacent channels of more than 20 dB. Simulated transmission coefficients are in close agreement with the required specification, and even exceed the performance specifications.

  6. 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.

  7. 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.

  8. State Geography Using NOAA Polar-Orbiting Satellites.

    ERIC Educational Resources Information Center

    Stadler, Stephen J.

    1985-01-01

    NOAA polar-orbiting satellites have the capability of providing views of entire states. This article describes the characteristics of data from these satellites, indicates their advantages and disadvantages, and shows how the satellite data can be used in a statewide representation of physical geography for students at the introductory level. (RM)

  9. Discovery of 12 satellites of Saturn exhibiting orbital clustering.

    PubMed

    Gladman, B; Kavelaars, J J; Holman, M; Nicholson, P D; Burns, J A; Hergenrother, C W; Petit, J M; Marsden, B G; Jacobson, R; Gray, W; Grav, T

    2001-07-12

    The giant planets in the Solar System each have two groups of satellites. The regular satellites move along nearly circular orbits in the planet's orbital plane, revolving about it in the same sense as the planet spins. In contrast, the so-called irregular satellites are generally smaller in size and are characterized by large orbits with significant eccentricity, inclination or both. The differences in their characteristics suggest that the regular and irregular satellites formed by different mechanisms: the regular satellites are believed to have formed in an accretion disk around the planet, like a miniature Solar System, whereas the irregulars are generally thought to be captured planetesimals. Here we report the discovery of 12 irregular satellites of Saturn, along with the determinations of their orbits. These orbits, along with the orbits of irregular satellites of Jupiter and Uranus, fall into groups on the basis of their orbital inclinations. We interpret this result as indicating that most of the irregular moons are collisional remnants of larger satellites that were fragmented after capture, rather than being captured independently. PMID:11449267

  10. Impulse strobing method in superlong baseline radiointerferometry for observing geostationary artificial Earth satellites.

    NASA Astrophysics Data System (ADS)

    Gorodetskij, V. M.

    The new possibility of synthesizing the wide frequency band for the VLBI observation of slowly moving objects with the standard MARK-1 processing system using the impulse strobing method is described. It is shown that the signal-to-noise ratio may be improved due to specific type of the impulse function. An original system of realization of these methods in the satellite VLBI observation is suggested.

  11. 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.

  12. 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.

  13. Mechanism for Retrieving Satellites From Orbit

    NASA Technical Reports Server (NTRS)

    Harwell, W. D.; Gardner, D. A.

    1987-01-01

    Pair of documents describe mechanism allowing astronaut to capture in extravehicular activity small artificial satellite for retrieval and return to Earth. Mechanism operates by insertion of probe in nozzle of rocket motor on satellite, followed by expansion of inserted probe end to grasp motor inside nozzle and thereby capture satellite. Designed for specific satellite, but operating principle adapted to almost any satellite equipped with rocket motor or possibly used in retrieval of hollow-shaped objects in marine and other salvage operations.

  14. On-orbit checkout study. [for the synchronous meteorological satellite and the technology demonstration satellite

    NASA Technical Reports Server (NTRS)

    Pritchard, E. I.

    1977-01-01

    The spaceborne testing equipment carried by the orbiter and the measuring equipment onboard the satellite (telemetry) is tested to verify that each is operating satisfactorily. The satellite command system is also checked. Thermal stabilization with the satellite in the orbiter shadow is achieved in six to eight hours. Satellite subsystem tests are run, and thermal control by heaters is checked. Thermal stabilization with the satellite exposed to the sun (when the orbiter is in sunlight) is again achieved in an estimated six to eight hours. Subsystem tests are again run in the hot condition, and heat rejection tests are made.

  15. Space Environment Monitoring System in next generation Geostationary Meteorological Satellite of China

    NASA Astrophysics Data System (ADS)

    Xin, Zhang

    Feng Yun 4(FY-4) is a second-generation Meteorological Remote Sensing earth observation satellite of China. On board FY-4, Space Environment Monitoring System(SEMS) consist of seven payloads, including 3 High Energy Particle Detector(HEPD), 1 Magnetometer(MTM), 1 Charging Potential Probe(CPP) and 1 Radiation Dosimeter(RD). High energy particle , magnetic field and space environment effect compose of main goals of SEMS. The HEPD instrument will detect proton with 3 directions , electron with 9 directions. Magnetometer will monitor magnetic field intensity between -400nT and +400nT. CPP will monitor Relative Surface Voltage from -10KV to +1KV, Absolute Surface Voltage from -20KV to -100V ,+100V to +1KV, Deep Surface Voltage from -2.5KV to 0V. RD will monitor dose from 0 rad to 200,000 rad. The first FY-4 satellite is planned to be launched in Dec 2015,This next-generation system will continue to provide more information about space weather, and SEMS will be playing more important role in space weather.

  16. Development of a Cloud-Top Height Estimation Method by Geostationary Satellite Split-Window Measurements Trained with CloudSat Data

    NASA Astrophysics Data System (ADS)

    Hamada, Atsushi; Nishi, Noriyuki; Inoue, Toshiro

    2010-05-01

    Estimation of cloud-top height and visible optical thickness of upper-tropospheric clouds by brightness temperature (TB) measurements of geostationary satellite at two infrared split-window wavelengths was conducted. These cloud parameters were estimated by regressing the measurements of 94-GHz cloud radar onboard CloudSat satellite in terms of TB at 10.8 um (T11) and its difference from TB at 12 um (?T = T11 -T12) measured by geostationary satellite MTSAT-1R. Estimation by geostationary satellite measurements are fairly useful in field campaigns aiming mesoscale cloud systems, where cloud-top heights are compared with the vertical profiles of ground-based measurements such as wind and cloud condensates in a short time interval. Hamada et al. (2008) conducted the estimation of cloud-top height by T11 and ?T measured by GMS-5, using ship-borne cloud radar measurements. However, their ground-based result was limited to the non-rainy clouds, since cloud radar signal is heavily attenuated by precipitation particles. Spaceborne radar measurements enables an estimation of cloud-top height without concern for the existence of precipitation. We examined the dependences of the estimates of cloud-top height on latitude, season, satellite zenith angle, day-night, and land-sea differences. It was shown that these dependences were considered as being uniform in tropics, except for the region with large satellite zenith angle. The dependences on latitude and season were negligible in tropics, while they became the most significant factor affecting the estimates at higher latitudes. Estimation of visible optical thickness was also conducted, although limited to the non-rainy high clouds. The distributions of estimates in TB-?T space were qualitatively consistent with those expected from a simplified radiative transfer equation, although the standard deviations of measurements were slightly large. The near real-time products has already been provided on our Website (http://www-clim.kugi.kyoto-u.ac.jp/hamada/ctop/). Since the CloudSat conducts cloud radar observations on a global scale, the method adopted in this study can easily be applied to other current geostationary satellites with split-window channels, yielding hourly estimation map of cloud-top and optical thickness in global scale. We will show the results also using Meteosat Second Generation measurements.

  17. Orbital evolution and origin of the Martian satellites

    SciTech Connect

    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. 91 references.

  18. 47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... satellites, the blanket license will cover a specified number of space stations to operate in a specified number of orbital planes. In the case of geostationary satellites, as part of a geostationary-only... (2) Launch of this space station will not cause the licensee to exceed the total number of...

  19. 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.

  20. Investigation of cloud/water vapor motion winds from geostationary satellite

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This report summarizes the research work accomplished on the NASA grant contract NAG8-892 during 1992. Research goals of this contract are the following: to complete upgrades to the Cooperative Institute for Meteorological Satellite Studies (CIMSS) wind system procedures for assigning heights and incorporating first guess information; to evaluate these modifications using simulated tracer fields; to add an automated quality control system to minimize the need for manual editing, while maintaining product quality; and to benchmark the upgraded algorithm in tests with NMC and/or MSFC. Work progressed on all these tasks and is detailed. This work was done in collaboration with CIMSS NOAA/NESDIS scientists working on the operational winds software, so that NASA funded research can benefit NESDIS operational algorithms.

  1. Long time dynamical evolution of highly elliptical satellites orbits

    NASA Astrophysics Data System (ADS)

    Kuznetsov, E.; Zakharova, P.

    2015-08-01

    Dynamical evolution of objects near Molniya-type orbits is considered. Initial conditions correspond to highly elliptical satellite orbits with eccentricities 0.65 and a critical inclination 63.4. Semi-major axis is varied near resonant value 26560 km in an interval 500 km. Variations were analyzed for positional orbital elements, an ascending node longitude and an argument of pericenter. Initial conditions determined when orbital elements variations are minimal. These regions can be used as orbits for safe stationing satellites which finish work on Molniya-type orbits. The study of dynamical evolution on long time intervals was performed on the basis of the results of numerical simulation. The model of disturbing forces taken into account the main perturbing factors. Time interval was up to 24 yr. Area-to-mass ratio varied from small values corresponding to satellites to big ones corresponding to space debris.

  2. Photometric Database of the geostationary satellites Astronomical Observatory of I. Mechnikov Odessa national university (in Russian)

    NASA Astrophysics Data System (ADS)

    Sukhov, P., P.

    In many cases role not coordinate information (photometrical, polarization, spectral) can be key when determining a class spacecraft, its functional purpose. At each class GSS can be design and dynamic features which are shown on a form light curve also have a characteristic appearance (signature). What features help to classify GSS on light curve. The light curves GSS can determine the operating mode on the device orbit reveal signs of an emergency operation, the transition from the GSS conserved active state. In recent years, for the identification of the GSS, many experts make photometric database (DB) comprising a set of characteristics, with sufficient probability characterizing a particular class of spacecraft. Database AO ONU contains more than 800 light curves in B, V, R filters 120 GSS. Showing light curves several GSS with distinctive structural and dynamic features, peculiar to the respective classes of spacecraft.

  3. Parallel orbit propagation and the analysis of satellite constellations

    NASA Astrophysics Data System (ADS)

    Wallace, Scott T.

    1995-06-01

    This thesis describes the development of a scalable, portable parallel orbit propagator, with application to the analysis of satellite constellations, The Draper Semianalytic Satellite Theory (DSST) is coupled with the Parallel Virtual Machine (PVM) software package to demonstrate the power of the networked computing paradigm. The PVM/DSST is employed to analyze the stability of the 840 satellite Teledesic constellation, as described in the 1994 FCC filing, under real-world perturbations. Combined with genetic algorithm optimization software, the frozen orbit of a satellite in the presence of arbitrary perturbations is easily determined. This concept is extended to automate constellation design for optimal performance.

  4. 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.

  5. GPS-Based Navigation and Orbit Determination for the AMSAT Phase 3D Satellite

    NASA Technical Reports Server (NTRS)

    Davis, George; Carpenter, Russell; Moreau, Michael; Bauer, Frank H.; Long, Anne; Kelbel, David; Martin, Thomas

    2002-01-01

    This paper summarizes the results of processing GPS data from the AMSAT Phase 3D (AP3) satellite for real-time navigation and post-processed orbit determination experiments. AP3 was launched into a geostationary transfer orbit (GTO) on November 16, 2000 from Kourou, French Guiana, and then was maneuvered into its HEO over the next several months. It carries two Trimble TANS Vector GPS receivers for signal reception at apogee and at perigee. Its spin stabilization mode currently makes it favorable to track GPS satellites from the backside of the constellation while at perigee, and to track GPS satellites from below while at perigee. To date, the experiment has demonstrated that it is feasible to use GPS for navigation and orbit determination in HEO, which will be of great benefit to planned and proposed missions that will utilize such orbits for science observations. It has also shown that there are many important operational considerations to take into account. For example, GPS signals can be tracked above the constellation at altitudes as high as 58000 km, but sufficient amplification of those weak signals is needed. Moreover, GPS receivers can track up to 4 GPS satellites at perigee while moving as fast as 9.8 km/sec, but unless the receiver can maintain lock on the signals long enough, point solutions will be difficult to generate. The spin stabilization of AP3, for example, appears to cause signal levels to fluctuate as other antennas on the satellite block the signals. As a result, its TANS Vectors have been unable to lock on to the GPS signals long enough to down load the broadcast ephemeris and then generate position and velocity solutions. AP3 is currently in its eclipse season, and thus most of the spacecraft subsystems have been powered off. In Spring 2002, they will again be powered up and AP3 will be placed into a three-axis stabilization mode. This will significantly enhance the likelihood that point solutions can be generated, and perhaps more important, that the receiver clock can be synchronized to GPS time. This is extremely important for real-time and post-processed orbit determination, where removal of receiver clock bias from the data time tags is needed, for time-tagging of science observations. Current analysis suggests that the inability to generate point solutions has allowed the TANS Vector clock bias to drift freely, being perhaps as large as 5-7 seconds by October, 2001, thus causing up to 50 km of along-track orbit error. The data collected in May, 2002 while in three-axis stabilized mode should provide a significant improvement in the orbit determination results.

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

    NASA Technical Reports Server (NTRS)

    1991-01-01

    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. Characterization of an In-Situ Ground Terminal via a Geostationary Satellite

    NASA Technical Reports Server (NTRS)

    Piasecki, Marie T.; Welch, Bryan W.; Mueller, Carl H.

    2015-01-01

    In 2015, the Space Communications and Navigation (SCaN) Testbed project completed an S-Band ground station located at the NASA Glenn Research Center in Cleveland, Ohio. This S-Band ground station was developed to create a fully characterized and controllable dynamic link environment when testing novel communication techniques for Software Defined Radios and Cognitive Communication Systems. In order to provide a useful environment for potential experimenters, it was necessary to characterize various RF devices at both the component level in the laboratory and at the system level after integration. This paper will discuss some of the laboratory testing of the ground station components, with a particular focus/emphasis on the near-field measurements of the antenna. It will then describe the methodology for characterizing the installed ground station at the system level via a Tracking and Data Relay Satellite (TDRS), with specific focus given to the characterization of the ground station antenna pattern, where the max TDRS transmit power limited the validity of the non-noise floor received power data to the antenna main lobe region. Finally, the paper compares the results of each test as well as provides lessons learned from this type of testing methodology.

  8. Characterization of an In-Situ Ground Terminal via a Geostationary Satellite

    NASA Technical Reports Server (NTRS)

    Piasecki, Marie; Welch, Bryan; Mueller, Carl

    2015-01-01

    In 2015, the Space Communications and Navigation (SCaN) Testbed project completed an S-Band ground station located at the NASA Glenn Research Center in Cleveland, Ohio. This S-Band ground station was developed to create a fully characterized and controllable dynamic link environment when testing novel communication techniques for Software Defined Radios and Cognitive Communication Systems. In order to provide a useful environment for potential experimenters, it was necessary to characterize various RF devices at both the component level in the laboratory and at the system level after integration. This paper will discuss some of the laboratory testing of the ground station components, with a particular focus emphasis on the near-field measurements of the antenna. It will then describe the methodology for characterizing the installed ground station at the system level via a Tracking and Data Relay Satellite (TDRS), with specific focus given to the characterization of the ground station antenna pattern, where the max TDRS transmit power limited the validity of the non-noise floor received power data to the antenna main lobe region. Finally, the paper compares the results of each test as well as provides lessons learned from this type of testing methodology.

  9. 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.

  10. Precise science orbits for the Swarm satellite constellation

    NASA Astrophysics Data System (ADS)

    van den IJssel, Jose; Encarnação, João; Doornbos, Eelco; Visser, Pieter

    2015-09-01

    The European Space Agency (ESA) Swarm mission was launched on 22 November 2013 to study the dynamics of the Earth's magnetic field and its interaction with the Earth system. The mission consists of three identical satellites, flying in carefully selected near polar orbits. Two satellites fly almost side-by-side at an initial altitude of about 480 km, and will descend due to drag to around 300 km during the mission lifetime. The third satellite was placed in a higher orbit of about 530 km altitude, and therefore descends much more slowly. To geolocate the Swarm observations, each satellite is equipped with an 8-channel, dual-frequency GPS receiver for Precise Orbit Determination (POD). Onboard laser retroreflectors provide the opportunity to validate the orbits computed from the GPS observations using Satellite Laser Ranging (SLR) data. Precise Science Orbits (PSOs) for the Swarm satellites are computed by the Faculty of Aerospace Engineering at Delft University of Technology in the framework of the Swarm Satellite Constellation Application and Research Facility (SCARF). The PSO product consists of both a reduced-dynamic and a kinematic orbit solution. After a short description of the Swarm GPS data characteristics, the adopted POD strategy for both orbit types is explained and first PSO results from more than one year of Swarm GPS data are presented. Independent SLR validation shows that the reduced-dynamic Swarm PSOs have an accuracy of better than 2 cm, while the kinematic orbits have a slightly reduced accuracy of about 4-5 cm. Orbit comparisons indicate that the consistency between the reduced-dynamic and kinematic Swarm PSO for most parts of the Earth is at the 4-5 cm level. Close to the geomagnetic poles and along the geomagnetic equator, however, the kinematic orbits show larger errors, which are probably due to ionospheric scintillations that affect the Swarm GPS receivers over these areas.

  11. The effect of observation geometry on single-channel aerosol retrievals from geostationary satellites in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Paronis, Dimitris; Hatzopoulos, John; Dulac, Francois

    2010-05-01

    Satellite remote sensing is nowadays used for aerosol monitoring on an operational basis via specially designed algorithms which are based on multidimensional data. The development of sensors suitable for aerosol monitoring, has given way to the implementation of algorithms for multispectral (e.g. MODIS, MERIS and SEVIRI sensors), hyper-spectral (e.g. CHRIS sensor), multi-angle (e.g. MISR and CHRIS sensors) and multi-polarization observations (e.g. POLDER sensor) both over ocean and land. These sensors have been providing data on a continuous basis for less than two decades (e.g. MODIS archived aerosol data are available since 2001), a period which cannot be considered adequate for studies related to global climate change. On the other hand, archived data from the first generation meteorological sensors such as AVHRR and MVIRI (aboard the NOAA and METEOSAT series satellites respectively) span a period of almost thirty years a fact that is challenging as regards re-processing of such data. In the past, single channel algorithms developed for operational AOD retrievals over oceans have been successfully applied with METEOSAT data (Moulin et al. 1997) and are still used on an operational basis in several cases for AVHRR (Ignatov et al. 2004), SEVIRI (Bridley & Ignatov 2006) and MODIS (Ignatov et al. 2006).One of the main limitations of such algorithms affecting the accuracy of the AOD retrievals is the need for a universal aerosol model. Such an approach although have led to accurate results in open oceanic areas it can be problematic in more complex environments such as the Mediterranean where multiple types of aerosol particles (i.e. desert dust, pollution aerosol and oceanic particles) are encountered (Myhre et al. 2005). In the present paper the expected accuracy of a single channel algorithm developed for the visible MVIRI band is assessed as a function of the aerosol model and the geometry of observation of the geostationary METEOSAT satellite. Two different aerosol models are used as candidate models corresponding to desert dust and water soluble particles encountered in the Mediterranean region. The theoretical simulations were based on radiative transfer computations performed with the 6S code. Results showed that that optimum geometries can be defined where the AOD error is minimized. The results are confirmed using Meteosat-6 data along with concurrent AERONET measurements from the Mediterranean. References Brindley, H, and A. Ignatov, 2006: Retrieval of mineral aerosol optical depth and size information from Meteosat Second Generation solar reflectance bands, Remote Sens. Env., 102, 344-363. Ignatov, A., Sapper, J., Laszlo, I., Nalli, N., and K. Kidwell, 2004: Operational Aerosol Observations (AEROBS) from AVHRR/3 onboard NOAA-KLM satellites. J.Atm.Ocean.Tech., 21, 3-26. Ignatov, A., Minnis, P., Miller, W., Wielicki, B., and L.Remer, 2006: Consistency of global MODIS Aerosol Optical Depths over ocean on Terra and Aqua CERES SSF Datasets. J.Geophys.Res., 111, D14202. Moulin, C., Guillard, F. , Dulac, F. , and C. E. Lambert, 1997 : Long-term daily monitoring of Saharan dust load over ocean using Meteosat ISCCP-B2 data 1. Methodology and preliminary results for 1983-1994 in the Mediterranean, J. Geophys. Res., 102(D14), 16,947-16,958. Myhre, G., Stordal, F., Johnsrud, M., Diner, D.J., Geogdzhayev, I.V., Haywood, J.M., Holben, B., Holzer-Popp, T., Ignatov, A., Kahn, R., Kaufman, Y.J., Loeb, N., Martonshik, J., Mishchenko, M.I., Nalli, N.R., Remer, L.A., Schroedter- Homscheidt, M., Tanr, D., Torres, O. and Want, M., 2005: Intercomparison of satellite retrieved aerosol optical depth over ocean during the period September 1997 to December 2000, Atmos Chem and Phys, 5, 1697-1719.

  12. Tidal debris morphology and the orbits of satellite galaxies

    NASA Astrophysics Data System (ADS)

    Hendel, David; Johnston, Kathryn V.

    2015-12-01

    How do galaxies move relative to one another? While we can examine the motion of dark matter subhaloes around their hosts in simulations of structure formation, determining the orbits of satellites around their parent galaxies from observations is impossible except for a small number of nearby cases. In this work, we outline a novel approach to probing the orbital distributions of infalling satellite galaxies using the morphology of tidal debris structures. It has long been understood that the destruction of satellites on near-radial orbits tends to lead to the formation of shells of debris, while those on less eccentric orbits produce tidal streams. We combine an understanding of the scaling relations governing the orbital properties of debris with a simple model of how these orbits phase-mix over time to produce a `morphology metric' that more rigorously quantifies the conditions required for shells to be apparent in debris structures as a function of the satellite's mass and orbit and the interaction time. Using this metric we demonstrate how differences in orbit distributions can alter the relative frequency of shells and stream structures observed around galaxies. These experiments suggest that more detailed modelling and careful comparisons with current and future surveys of low surface brightness features around nearby galaxies should be capable of actually constraining orbital distributions and provide new insights into our understanding of structure formation.

  13. Electric Propulsion for Low Earth Orbit Communication Satellites

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.

    1997-01-01

    Electric propulsion was evaluated for orbit insertion, satellite positioning and de-orbit applications on big (hundreds of kilograms) and little (tens of kilograms) low earth orbit communication satellite constellations. A simple, constant circumferential thrusting method was used. This technique eliminates the complex guidance and control required when shading of the solar arrays must be considered. Power for propulsion was assumed to come from the existing payload power. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion ammonia resistojets, ion, Hall, and pulsed plasma thrusters allowed an additional spacecraft per launch Typical orbit insertion and de-orbit times were found to range from a few days to a few months.

  14. 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.

  15. 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.

  16. Qualitative features of the evolution of some polar satellite orbits

    NASA Astrophysics Data System (ADS)

    Vashkov'yak, M. A.

    2016-01-01

    Two special cases of the problem of the secular perturbations in the orbital elements of a satellite with a negligible mass produced by the joint influence of the oblateness of the central planet and the attraction by its most massive (or main) satellites and the Sun are considered. These cases are among the integrable ones in the general nonintegrable evolution problem. The first case is realized when the plane of the satellite orbit and the rotation axis of the planet lie in its orbital plane. The second case is realized when the plane of the satellite orbit is orthogonal to the line of intersection between the equatorial and orbital planes of the planet. The corresponding particular solutions correspond to those polar satellite orbits for which the main qualitative features of the evolution of the eccentricity and pericenter argument are described here. Families of integral curves have been constructed in the phase plane of these elements for the satellite systems of Jupiter, Saturn, and Uranus.

  17. Effects of the Satellite Power System on low Earth orbit and geosynchronous satellites

    NASA Astrophysics Data System (ADS)

    Grant, W. B.; Morrison, E. L.; Juroshek, J. R.

    1981-06-01

    The large amount of power contained in the main beam and principal sidelobes of the proposed Solar Power System (SPS), now under study by DOE and NASA, potentially presents an EMC problem for other satellite systems. This report examines selected geosynchronous orbit (GEO) satellites in adjacent slots to an SPS, GEO satellites on a chord passing an Earth horizon, and low-earth-orbit (LEO) satellites which may pass throught the SPS power beam. Potential functional and operational impacts to on-board systems are analyzed. Mitigation techniques for SPS effects are examined, and recommendations summarized to allow satellites to operate satisfactorily in an SPS environment.

  18. 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.

  19. 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 Astrophysics Data System (ADS)

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

    2014-10-01

    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 NASAs Decadal Survey Mission GEO-CAPE (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 O2A 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.

  20. PCW/PHEOS-WCA: quasi-geostationary Arctic measurements for weather, climate, and air quality from highly eccentric orbits

    NASA Astrophysics Data System (ADS)

    Lachance, Richard L.; McConnell, John C.; McElroy, C. Tom; O'Neill, Norm; Nassar, Ray; Buijs, Henry; Rahnama, Peyman; Walker, Kaley; Martin, Randall; Sioris, Chris; Garand, Louis; Trichtchenko, Alexander; Bergeron, Martin

    2012-09-01

    The PCW (Polar Communications and Weather) mission is a dual satellite mission with each satellite in a highly eccentric orbit with apogee ~42,000 km and a period (to be decided) in the 12-24 hour range to deliver continuous communications and meteorological data over the Arctic and environs. Such as satellite duo can give 247 coverage over the Arctic. The operational meteorological instrument is a 21-channel spectral imager similar to the Advanced Baseline Imager (ABI). The PHEOS-WCA (weather, climate and air quality) mission is intended as an atmospheric science complement to the operational PCW mission. The target PHEOS-WCA instrument package considered optimal to meet the full suite of science team objectives consists of FTS and UVS imaging sounders with viewing range of ~4.5 or a Field of Regard (FoR) ~ 34003400 km2 from near apogee. The goal for the spatial resolution at apogee of each imaging sounder is 1010 km2 or better and the goal for the image repeat time is targeted at ~2 hours or better. The FTS has 4 bands that span the MIR and NIR with a spectral resolution of 0.25 cm-1. They should provide vertical tropospheric profiles of temperature and water vapour in addition to partial columns of many other gases of interest for air quality. The two NIR bands target columns of CO2, CH4 and aerosol optical depth (OD). 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 and several other Air Quality (AQ) gases as well the Aerosol Index (AI).

  1. Pluto Satellite Orbits in Support of New Horizons

    NASA Astrophysics Data System (ADS)

    Buie, Marc

    2013-10-01

    We propose a sequence of observations that will significantlyimprove the orbit of P/2011 P1 and P/2012 P1 and provide useful improvementsto the orbits of other satellites in the Pluto system. The orbit determinationwork for the newest satellite discoveries are critically needed so thatNew Horizons can know where to point its instruments at close approach.These data will also be useful for improved mass constraints on the outersatellites as well as refining our knowledge of the photometric propertiesof all objects in the Pluto system. In particular, lightcurve and color evolution willbe monitored by these observations for use in constrainingmodels of seasonal evolution on Pluto.

  2. Orbit and clock determination of BDS regional navigation satellite system based on IGS M-GEX and WHU BETS tracking network

    NASA Astrophysics Data System (ADS)

    GENG, T.; Zhao, Q.; Shi, C.; Shum, C.; Guo, J.; Su, X.

    2013-12-01

    BeiDou Navigation Satellite System (BDS) began to provide the regional open service on December 27th 2012 and will provide the global open service by the end of 2020. Compared to GPS, the space segment of BDS Regional System consists of 5 Geostationary Earth Orbit satellites (GEO), 5 Inclined Geosynchronous Orbit satellites (IGSO) and 4 Medium Earth orbit (MEO) satellites. Since 2011, IGS Multiple-GNSS Experiment (M-GEX) focuses on tracking the newly available GNSS signals. This includes all signals from the modernized satellites of the GPS and GLONASS systems, as well as signals of the BDS, Galileo and QZSS systems. Up to now, BDS satellites are tracked by around 25 stations with a variety of different antennas and receivers from different GNSS manufacture communities in M-GEX network. Meanwhile, there are 17 stations with Unicore Communications Incorporation's GPS/BDS receivers in BeiDou Experimental Tracking Stations (BETS) network by Wuhan University. In addition, 5 BDS satellites have been tracking by the International Laser Ranging Service (ILRS). BDS performance is expected to be further studied by the GNSS communities. Following an introduction of the BDS system and above different tracking network, this paper discusses the achieved BDS characterization and performance assessment. Firstly, the BDS signal and measurement quality are analyzed with different antennas and receivers in detail compared to GPS. This includes depth of coverage for satellite observation, carrier-to-noise-density ratios, code noise and multipath, carrier phase errors. Secondly, BDS Precise Orbit Determination (POD) is processed. Different arc lengths and sets of orbit parameters are tested using Position And Navigation Data Analysis software (PANDA) which is developed at the Wuhan University. GEO, IGSO and MEO satellites orbit quality will be assessed using overlap comparison, 2-day orbit fit and external validations with Satellite Laser Range (SLR). Then BDS satellites are equipped with Rubidium clocks and clocks performance are also presented. Finally, benefits of BDS processing strategies and further developments are concluded.

  3. Orbit determination of Tance-1 satellite using VLBI data

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Hu, X. G.; Huang, C.; Jiang, D. R.

    2006-01-01

    On 30 December, 2003, China successfully launched the first satellite Tance-1 of Chinese Geospace Double Star Exploration Program, i.e. "Double Star Program (DSP)", on an improved Long March 2C launch vehicle. The Tance-1 satellite is operating at an orbit around the earth with a 550km perigee, 78000km apogee and 28.5 degree inclination.VLBI technique can track Tance-1 satellite or even far satellites such as lunar vehicles. To validate the VLBI technique in the on-going Chinese lunar exploration mission, Shanghai Astronomical Observatory (SHAO) organized to track the Tance-1 satellite with Chinese three VLBI stations: Shanghai, Kunming and Urumchi Orbit Determination (OD) of the Tance-1 satellite with about two days VLBI dada, and the capability of OD with VLBI data are studied. The results show that the VLBI-based orbit solutions improve the fit level over the initial orbit. The VLBI-delay-based orbit solution shows that the RMS of residuals of VLBI delay data is about 5.5m, and about 2.0cm/s for the withheld VLBI delay rate data. The VLBI-delay-rate-based orbit solution shows that the RMS of residuals of VLBI delay rate data is about 1.3cm/s, and about 29m for the withheld VLBI delay data. In the situation of orbit determination with VLBI delay and delay rate data with data sigma 5.5m and 1.3cm/s respectively, the RMS of residuals are 5.5,m and 2.0cm/s respectively. The simulation data assess the performance of the solutions. Considering the dynamic model errors of the Tance-1 satellite, the accuracy of the position is about km magnitude, and the accuracy of the velocity is about cm/s magnitude. The simulation work also show the dramatic accuracy improvement of OD with VLBI and USB combined.

  4. Orbit determination and prediction for Beidou GEO satellites at the time of the spring/autumn equinox

    NASA Astrophysics Data System (ADS)

    Li, XiaoJie; Zhou, JianHua; Hu, XiaoGong; Liu, Li; Guo, Rui; Zhou, ShanShi

    2015-08-01

    Geostationary (GEO) satellites form an indispensable component of the constellation of Beidou navigation system (BDS). The ephemerides, or predicted orbits of these GEO satellites(GEOs), are broadcast to positioning, navigation, and timing users. User equivalent ranging error (UERE) based on broadcast message is better than 1.5 m (root formal errors: RMS) for GEO satellites. However, monitoring of UERE indicates that the orbital prediction precision is significantly degraded when the Sun is close to the Earth's equatorial plane (or near spring or autumn Equinox). Error source analysis shows that the complicated solar radiation pressure on satellite buses and the simple box-wing model maybe the major contributor to the deterioration of orbital precision. With the aid of BDS' two-way frequency and time transfer between the GEOs and Beidou time (BDT, that is maintained at the master control station), we propose a new orbit determination strategy, namely three-step approach of the multi-satellite precise orbit determination (MPOD). Pseudo-range (carrier phase) data are transformed to geometric range (biased geometric range) data without clock offsets; and reasonable empirical acceleration parameters are estimated along with orbital elements to account for the error in solar radiation pressure modeling. Experiments with Beidou data show that using the proposed approach, the GEOs' UERE when near the autumn Equinox of 2012 can be improved to 1.3 m from 2.5 m (RMS), and the probability of user equivalent range error (UERE)<2.0 m can be improved from 50% to above 85%.

  5. 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.

  6. 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.

  7. 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.

  8. CASTOR: Cathode/Anode Satellite Thruster for Orbital Repositioning

    NASA Technical Reports Server (NTRS)

    Mruphy, Gloria A.

    2010-01-01

    The purpose of CASTOR (Cathode/Anode Satellite Thruster for Orbital Repositioning) satellite is to demonstrate in Low Earth Orbit (LEO) a nanosatellite that uses a Divergent Cusped Field Thruster (DCFT) to perform orbital maneuvers representative of an orbital transfer vehicle. Powered by semi-deployable solar arrays generating 165W of power, CASTOR will achieve nearly 1 km/s of velocity increment over one year. As a technology demonstration mission, success of CASTOR in LEO will pave the way for a low cost, high delta-V orbital transfer capability for small military and civilian payloads in support of Air Force and NASA missions. The educational objective is to engage graduate and undergraduate students in critical roles in the design, development, test, carrier integration and on-orbit operations of CASTOR as a supplement to their curricular activities. This program is laying the foundation for a long-term satellite construction program at MIT. The satellite is being designed as a part of AFRL's University Nanosatellite Program, which provides the funding and a framework in which student satellite teams compete for a launch to orbit. To this end, the satellite must fit within an envelope of 50cmx50cmx60cm, have a mass of less than 50kg, and meet stringent structural and other requirements. In this framework, the CASTOR team successfully completed PDR in August 2009 and CDR in April 2010 and will compete at FCR (Flight Competition Review) in January 2011. The complexity of the project requires implementation of many systems engineering techniques which allow for development of CASTOR from conception through FCR and encompass the full design, fabrication, and testing process.

  9. Optimal scheduling for satellite refuelling in circular orbits

    NASA Astrophysics Data System (ADS)

    Shen, Haijun

    The necessity of refuelling satellites arises from the idea of abandoning the current practice of replacing an existing satellite with a new one if the existing satellite is depleted of its onboard fuel. Being able to refuel satellites significantly reduces the cost in production, launching, and maintenance. This dissertation focuses on the scheduling issues arising from refuelling or servicing multiple satellites. The problem of refuelling a satellite constellation in a circular orbit in a given total time is considered primarily. Four major results are presented in this context. (1) An improvement has been developed to calculate the minimum-DeltaV fixed-time two-impulse rendezvous between two satellites in coplanar circular orbit using multiple-revolution Lambert's solution. In particular, a procedure is developed to quickly pick the minimum-DeltaV transfer orbit from multiple candidates. (2) Battin's formulation for solving Lambert's problem is extended so that it can be used to calculate the multiple-revolution solution. The basic idea is to reverse the order of the successive substitution described in Battin's method. (3) A solution to the scheduling problem of refuelling a satellite constellation with a single Refuelling Spacecraft (RSc) is obtained. First, given n satellites in a particular order and a total time, integer programming is used to obtain the minimum cost for the RSc to refuel these n satellites in the given order. A heuristic study is then conducted to determine the best refuelling sequence. It is found that the optimal refuelling sequence can be chosen from the sequences with the minimum total sweep angle. (4) Two variations of the peer-to-peer refuelling problem are studied. One problem assumes that the cost of rendezvous maneuvers between two satellites is negligible, and the other takes into consideration the rendezvous cost. Each of these problems is formulated and solved as a maximum-weight matching problem.

  10. Mapping Daily Evapotranspiration at Field to Global Scales using Geostationary and Polar Orbiting Satellite Imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 vegetati...

  11. 78 FR 14920 - Earth Stations Aboard Aircraft Communicating With Fixed-Satellite Service Geostationary-Orbit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-08

    ... Notice of Proposed Rulemaking in IB Docket No. 05-20 (Order) (70 FR 20508-01), recognizing the emergence... required to submit a copy of the manufacturer's range test plots of the antenna gain patterns specified...

  12. 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.

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

    ERIC Educational Resources Information Center

    Nous, Albert P.

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

  14. Analysis of the angle-only orbit determination for optical tracking strategy of Korea GEO satellite, COMS

    NASA Astrophysics Data System (ADS)

    Choi, Jin; Jo, Jung Hyun; Roh, Kyoung-Min; Son, Ju-Young; Kim, Myung-Jin; Choi, Young-Jun; Yim, Hong-Suh; Moon, Hong-Kyu; Kim, Bang-Yeop; Park, Jang-Hyun; Pavlis, Erricos C.

    2015-09-01

    Increasing numbers of Geostationary Earth Orbit satellites have led to the requirement of accurate station keeping and precise orbit prediction to avoid collision between satellites. In the case of ground-based optical observation, angular resolution is better than other tracking systems, such as radar systems; however, the observation time of optical observation is limited by weather or lighting conditions. To develop an effective optical observation strategy, the optical observation campaign from January to February 2014 for Communication, Ocean and Meteorological Satellite (COMS) was conducted. Because COMS is a controlled satellite with station keeping manoeuvres performed twice a week, the observation results for 1- and 2-day observations were analysed. Sparse and sporadic cases for the sequential observation of multiple satellites and a dense case for the intensive observation of specific targets were assumed for the experiments. In the 1-day arc observation experiment, the estimated orbits for dense observation cases over 10% of the orbital period showed that the maximum difference was less than 40 km (station keeping area) for 7-day propagation compared to the estimation result using the whole 1-day measurement. For the 2-day arc observation, the orbit estimation difference could be maintained within 2 km using a more frequent observation than the 1-h interval for 13 h that was used in the sparse case. Additionally, the longitudinal and latitudinal positions via the estimation result using the optical observation were compared with the Two-Line Elements (TLEs) and operator's data. Through this study, an adequate optical tracking strategy was studied, and the possibility of cooperation with other systems was also validated.

  15. Orbit design and control of planetary satellite orbiters in the Hill 3-body problem

    NASA Astrophysics Data System (ADS)

    Possner, Marci Paskowitz

    The exploration of planetary satellites by robotic spacecraft is currently of strong scientific interest. However, sending a spacecraft to a planetary satellite can be challenging due to strong perturbations from the central planet. The primary goal of this dissertation is to identify and utilize the main dynamical features of the system in the orbit design process. The system is modeled using a modified form of Hill's 3-body problem, where the effect of the planetary satellite's gravity field is included in the low-altitude analysis. A thorough study of the dynamics of the system is performed by applying averaging theory to reduce the complexity and degrees of freedom of the system. The reduced system has one degree of freedom (DOF) and has equilibrium solutions called frozen orbits. These frozen orbits are first used as targets for transfers from capture trajectories in 'safe zones'. The 'safe zones' in phase space are numerically determined; they contain trajectories that enter the Hill region and allow an uncontrolled spacecraft to remain in orbit without impact or escape for specified time periods. Transfers from safe trajectories to frozen orbits are identified and criteria on their costs evaluated. Unstable low-altitude, near-polar frozen orbits are the basis for the design of long lifetime science orbits. The stable and unstable manifolds of these frozen orbits in the 1-DOF system are investigated and the desired path for long lifetime orbits is identified. An algorithm is developed to systematically compute initial conditions in the full system such that the orbits follow the desired path and have sufficiently long lifetimes to be practical as science orbits about planetary satellites. The analysis of the control of a planetary satellite orbiter begins with the evaluation of the effect of orbit uncertainty on the science orbits and the identification of criteria to ensure that the orbits have the desired behavior. Then, two control schemes are developed: (a) given the terminal conditions of a science orbit, redesign a new science orbit and execute a low-cost transfer to it, (b) return the spacecraft to its nominal trajectory via a two-sequence set of maneuvers.

  16. An autonomous orbit determination method for MEO and LEO satellite

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Wang, Jin; Yu, Guobin; Zhong, Jie; Lin, Ling

    2014-09-01

    A reliable and secure navigation system and assured autonomous capability of satellite are in high demand in case of emergencies in space. This paper introduces a novel autonomous orbit determination method for Middle-Earth-Orbit and Low-Earth-Orbit (MEO and LEO) satellite by observing space objects whose orbits are known. Generally, the geodetic satellites, such as LAGEOS and ETALONS, can be selected as the space objects here. The precision CCD camera on tracking gimbal can make a series of photos of the objects and surrounding stars when MEO and LEO satellite encounters the space objects. Then the information processor processes images and attains sightings and angular observations of space objects. Several clusters of such angular observations are incorporated into a batch least squares filter to obtain an orbit determination solution. This paper describes basic principle and builds integrated mathematical model. The accuracy of this method is analyzed by means of computer simulation. Then a simulant experiment system is built, and the experimental results demonstrate the feasibility and effectiveness of this method. The experimental results show that this method can attain the accuracy of 150 meters with angular observations of 1 arcsecond system error.

  17. Orbits design for LEO space based solar power satellite system

    NASA Astrophysics Data System (ADS)

    Addanki, Neelima Krishna Murthy

    2011-12-01

    Space Based Solar Power satellites use solar arrays to generate clean, green, and renewable electricity in space and transmit it to earth via microwave, radiowave or laser beams to corresponding receivers (ground stations). These traditionally are large structures orbiting around earth at the geo-synchronous altitude. This thesis introduces a new architecture for a Space Based Solar Power satellite constellation. The proposed concept reduces the high cost involved in the construction of the space satellite and in the multiple launches to the geo-synchronous altitude. The proposed concept is a constellation of Low Earth Orbit satellites that are smaller in size than the conventional system. 7For this application a Repeated Sun-Synchronous Track Circular Orbit is considered (RSSTO). In these orbits, the spacecraft re-visits the same locations on earth periodically every given desired number of days with the line of nodes of the spacecraft's orbit fixed relative to the Sun. A wide range of solutions are studied, and, in this thesis, a two-orbit constellation design is chosen and simulated. The number of satellites is chosen based on the electric power demands in a given set of global cities. The orbits of the satellites are designed such that their ground tracks visit a maximum number of ground stations during the revisit period. In the simulation, the locations of the ground stations are chosen close to big cities, in USA and worldwide, so that the space power constellation beams down power directly to locations of high electric power demands. The j2 perturbations are included in the mathematical model used in orbit design. The Coverage time of each spacecraft over a ground site and the gap time between two consecutive spacecrafts visiting a ground site are simulated in order to evaluate the coverage continuity of the proposed solar power constellation. It has been observed from simulations that there always periods in which s spacecraft does not communicate with any ground station. For this reason, it is suggested that each satellite in the constellation be equipped with power storage components so that it can store power for later transmission. This thesis presents a method for designing the solar power constellation orbits such that the number of ground stations visited during the given revisit period is maximized. This leads to maximizing the power transmission to ground stations.

  18. Satellite probes plasma processes in earth orbit

    SciTech Connect

    Christensen, A.B.; Reasoner, D.L. NASA, Washington, DC )

    1992-01-01

    The mission of the DOD/NASA Combined Release and Radiation Effects Satellite (CRRES) is to deepen understanding of the earth's near-space environment, including the radiation belts and the ionosphere; this will help spacecraft designers protect against radiation-belt particles that affect onboard electronics, solar panel arrays, and crewmembers. Attention is presently given to CRRES's study of ionospheric plasma processes through releases of Ba, Ca, Sr, and Li at altitudes of 400-36,000 km. 4 refs.

  19. 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.

  20. A refined orbit for the satellite of asteroid (107) Camilla

    NASA Astrophysics Data System (ADS)

    Pajuelo, Myriam Virginia; Carry, Benoit; Vachier, Frederic; Berthier, Jerome; Descamp, Pascal; Merline, William J.; Tamblyn, Peter M.; Conrad, Al; Storrs, Alex; Margot, Jean-Luc; Marchis, Frank; Kervella, Pierre; Girard, Julien H.

    2015-11-01

    The satellite of the Cybele asteroid (107) Camilla was discovered in March 2001 using the Hubble Space Telescope (Storrs et al., 2001, IAUC 7599). From a set of 23 positions derived from adaptive optics observations obtained over three years with the ESO VLT, Keck-II and Gemini-North telescopes, Marchis et al. (2008, Icarus 196) determined its orbit to be nearly circular.In the new work reported here, we compiled, reduced, and analyzed observations at 39 epochs (including the 23 positions previously analyzed) by adding additional observations taken from data archives: HST in 2001; Keck in 2002, 2003, and 2009; Gemini in 2010; and VLT in 2011. The present dataset hence contains twice as many epochs as the prior analysis and covers a time span that is three times longer (more than a decade).We use our orbit determination algorithm Genoid (GENetic Orbit IDentification), a genetic based algorithm that relies on a metaheuristic method and a dynamical model of the Solar System (Vachier et al., 2012, A&A 543). The method uses two models: a simple Keplerian model to minimize the search-time for an orbital solution, exploring a wide space of solutions; and a full N-body problem that includes the gravitational field of the primary asteroid up to 4th order.The orbit we derive fits all 39 observed positions of the satellite with an RMS residual of only milli-arcseconds, which corresponds to sub-pixel accuracy. We found the orbit of the satellite to be circular and roughly aligned with the equatorial plane of Camilla. The refined mass of the system is (12 1) x 10^18 kg, for an orbital period of 3.71 days.We will present this improved orbital solution of the satellite of Camilla, as well as predictions for upcoming stellar occultation events.

  1. Relative motion of near orbiting satellites.

    NASA Technical Reports Server (NTRS)

    Eades, J. B., Jr.; Drewry, J. W.

    1973-01-01

    The relative motion of two particles on adjacent orbits about the same primary has been investigated under the condition that both motions have the same period. The geometrical properties of the relative displacement and velocity traces, on representative planes, are studied. A complete state of the motion is given; and, the range and range-rate variations, over one or more orbits, are described. It has been found that cusps appear on some of the traces provided that a proper relationship exists between the eccentricity and inclination. (Here, one particle moves on a circular path while the second moves on an ellipse). The conditions for which cusps appear are given, and typical traces are shown.

  2. 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).

  3. Near-optimal geostationary transfer maneuvers with cooperative en-route inspection using hybrid optimal control

    NASA Astrophysics Data System (ADS)

    Showalter, Daniel J.; Black, Jonathan T.

    2014-12-01

    This research investigates the performance of bi-level hybrid optimal control algorithms in the solution of minimum delta-velocity geostationary transfer maneuvers with cooperative en-route inspection. The maneuvers, introduced here for the first time, are designed to populate a geostationary constellation of space situational awareness satellites while providing additional characterization of objects in lower-altitude orbit regimes. The maneuvering satellite, called the chaser, performs a transfer from low Earth orbit to geostationary orbit, during which it performs an inspection of one of several orbiting targets in conjunction with a ground site for the duration of the target's line-of-site contact with that site. A three-target scenario is used to test the performance of multiple bi-level hybrid optimal control algorithms. A bi-level hybrid algorithm is then utilized to solve fifteen-, and thirty-target scenarios and shown to have increasing benefit to complete enumeration as the number of targets is increased. Results indicate that the en-route inspection can be accomplished for a small increase in the delta-velocity required for a simple transfer to geostationary orbit given the same initial conditions.

  4. 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.

  5. 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.

  6. The Orbital Design of Alpha Centauri Exoplanet Satellite (ACESat)

    NASA Technical Reports Server (NTRS)

    Weston, Sasha; Belikov, Rus; Bendek, Eduardo

    2015-01-01

    Exoplanet candidates discovered by Kepler are too distant for biomarkers to be detected with foreseeable technology. Alpha Centauri has high separation from other stars and is of close proximity to Earth, which makes the binary star system 'low hanging fruit' for scientists. Alpha Centauri Exoplanet Satellite (ACESat) is a mission proposed to Small Explorer Program (SMEX) that will use a coronagraph to search for an orbiting planet around one of the stars of Alpha Centauri. The trajectory design for this mission is presented here where three different trajectories are considered: Low Earth Orbit (LEO), Geosynchronous Orbit (GEO) and a Heliocentric Orbit. Uninterrupted stare time to Alpha Centauri is desirable for meeting science requirements, or an orbit that provides 90% stare time to the science target. The instrument thermal stability also has stringent requirements for proper function, influencing trajectory design.

  7. Determination of the orbits of inner Jupiter satellites

    NASA Astrophysics Data System (ADS)

    Avdyushev, V. A.; Ban'shikova, M. A.

    2008-08-01

    Some problems in determining the orbits of inner satellites associated with the complex behavior of the target function, which is strongly ravine and which possesses multiple minima in the case of the satellite orbit is determined based on fragmentary observations distributed over a rather long time interval, are studied. These peculiarities of the inverse problems are considered by the example of the dynamics of the inner Jupiter satellites: Amalthea, Thebe, Adrastea, and Metis. Numerical models of the satellite motions whose parameters were determined based on ground-based observations available at the moment to date have been constructed. A composite approach has been proposed for the effective search for minima of the target function. The approach allows one to obtain the respective evaluations of the orbital parameters only for several tens of iterations even in the case of very rough initial approximations. If two groups of observations are available (Adrastea), a formal minimization of the target function is shown to give a solution set, which is the best solution from the point of view of representation of the orbital motion, which is impossible to choose. Other estimates are given characterizing the specific nature of the inverse problems.

  8. Application and analysis of satellite orbit prediction techniques

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The numerical accuracy of a satellite orbit computation program was investigated. The effects of roundoff and truncation errors on the solution were determined. New formulations that have the mean motion based on the total energy are compared to the more classical formulations and evaluated via numerical experiments.

  9. Microlensing planet detection via geosynchronous and low Earth orbit satellites

    NASA Astrophysics Data System (ADS)

    Mogavero, F.; Beaulieu, J. P.

    2016-01-01

    Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale tE, which prevents mass and distance of the lens to be univocally determined. It has been shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events (tE ≈ 20 days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, tE ≈ 1 day, when dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite on even shorter timescales, tE ≈ 0.1 days. A Fisher matrix analysis is employed to predict how the 1-σ error on parallax depends on tE and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth-mass free-floating planets. Limitations to these results can be the strong requirements on the photometry, the effects of blending, and in the case of the low orbit, the Earth's umbra.

  10. Orbital radiation exposure of the Astronomical Netherlands Satellite (ANS)

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.

    1971-01-01

    The orbital electron and proton flux calculations were performed for determining the applicability of COS/MOS ciruits for the ANS computer and X-ray experiment logic. The results for electrons, protons, and the total lifetime the satellite spends in flux-free regions are presented in tables and graphs.

  11. GIST-PM-Asia v1: development of a numerical system to improve particulate matter forecasts in South Korea using geostationary satellite-retrieved aerosol optical data over Northeast Asia

    NASA Astrophysics Data System (ADS)

    Lee, S.; Song, C. H.; Park, R. S.; Park, M. E.; Han, K. M.; Kim, J.; Choi, M.; Ghim, Y. S.; Woo, J.-H.

    2016-01-01

    To improve short-term particulate matter (PM) forecasts in South Korea, the initial distribution of PM composition, particularly over the upwind regions, is primarily important. To prepare the initial PM composition, the aerosol optical depth (AOD) data retrieved from a geostationary equatorial orbit (GEO) satellite sensor, GOCI (Geostationary Ocean Color Imager) which covers a part of Northeast Asia (113-146° E; 25-47° N), were used. Although GOCI can provide a higher number of AOD data in a semicontinuous manner than low Earth orbit (LEO) satellite sensors, it still has a serious limitation in that the AOD data are not available at cloud pixels and over high-reflectance areas, such as desert and snow-covered regions. To overcome this limitation, a spatiotemporal-kriging (STK) method was used to better prepare the initial AOD distributions that were converted into the PM composition over Northeast Asia. One of the largest advantages in using the STK method in this study is that more observed AOD data can be used to prepare the best initial AOD fields compared with other methods that use single frame of observation data around the time of initialization. It is demonstrated in this study that the short-term PM forecast system developed with the application of the STK method can greatly improve PM10 predictions in the Seoul metropolitan area (SMA) when evaluated with ground-based observations. For example, errors and biases of PM10 predictions decreased by ˜ 60 and ˜ 70 %, respectively, during the first 6 h of short-term PM forecasting, compared with those without the initial PM composition. In addition, the influences of several factors on the performances of the short-term PM forecast were explored in this study. The influences of the choices of the control variables on the PM chemical composition were also investigated with the composition data measured via PILS-IC (particle-into-liquid sampler coupled with ion chromatography) and low air-volume sample instruments at a site near Seoul. To improve the overall performances of the short-term PM forecast system, several future research directions were also discussed and suggested.

  12. 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.

  13. 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.

  14. 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.

  15. On-orbit checkout of satellites, volume 2. Part 3 of on-orbit checkout study. [space maintenance

    NASA Technical Reports Server (NTRS)

    Pritchard, E. I.

    1978-01-01

    Early satellite failures significantly degrading satellite operations are reviewed with emphasis on LANDSAT D, the Technology Demonstration Satellite, the ATREX/AEM spacecraft, STORMSAT 2, and the synchronous meteorological satellite. Candidates for correction with on-orbit checkout and appropriate actions are analyzed. On-orbit checkout subsystem level studies are summarized for electrical power, attitude control, thermal control, reaction control and propulsion, instruments, and angular rate matching for alignment of satellite IRU.

  16. Advances in precision orbit determination of GRACE satellites

    NASA Astrophysics Data System (ADS)

    Bettadpur, Srinivas; Save, Himanshu; Kang, Zhigui

    The twin Gravity Recovery And Climate Experiment (GRACE) satellites carry a complete suite of instrumentation essential for precision orbit determination (POD). Dense, continuous and global tracking is provided by the Global Positioning System receivers. The satellite orientation is measured using two star cameras. High precision measurements of non-gravitational accel-erations are provided by accelerometers. Satellite laser ranging (SLR) retroreflectors are used for collecting data for POD validation. Additional validation is provided by the highly precise K-Band ranging system measuring distance changes between the twin GRACE satellites. This paper presents the status of POD for GRACE satellites. The POD quality will be vali-dated using the SLR and K-Band ranging data. The POD quality improvement from upgraded modeling of the GPS observations, including the transition to the new IGS05 standards, will be discussed. In addition, the contributions from improvements in the gravity field modeling -partly arising out of GRACE science results -will be discussed. The aspects of these improve-ments that are applicable for the POD of other low-Earth orbiting satellites will be discussed as well.

  17. Measurement of total electron content of midlatitude ionosphere and protonosphere via Faraday rotation and group relay techniques using transmission from geostationary satellites ATS-3 and ATS-6

    NASA Technical Reports Server (NTRS)

    Paul, M. P.

    1982-01-01

    Measurement of integrated columnar electron content and total electron content for the local ionosphere and the overlying protonosphere via Faraday rotation and group delay techniques has proven very useful. A field station was established having the geographic location of 31.5 deg N latitude and 91.06 deg W longitude to accomplish these objectives. A polarimeter receiving system was set up in the beginning to measure the Faraday rotation of 137.35 MHz radio signal from geostationary satellite ATS 3 to yield the integrated columnar electron content of the local ionosphere. The measurement was continued regularly, and the analysis of the data thus collected provided a synopsis of the statistical variation of the ionosphere along with the transient variations that occurred during the periods of geomagnetic and other disturbances.

  18. Evaluation of Temperature and Material Combinations on Several Lubricants for Use in the Geostationary Operational Environmental Satellite (GOES) Mission Filter Wheel Bearings

    NASA Technical Reports Server (NTRS)

    Jansen, Mark J.; Jones, William R., Jr.; Predmore, Roamer E.

    2001-01-01

    A bearing test apparatus was used to investigate lubricant degradation rates and elastohydrodynamic transition temperatures for several perfluoropolyether (Krytox) formulations, a pentasilahydrocarbon, and a synthetic hydrocarbon (Pennzane 2001 A) in an MPB 1219 bearing, which is used in the geostationary operational environmental satellite (GOES) mission filter wheel assembly. Test conditions were the following: 1000-hr duration, 75 C, 20 lb axial load, vacuum level less than 1 x 10(exp -6) Torr, and a 600-rpm rotational speed. Baseline tests were performed using unformulated Krytox 143AB, the heritage lubricant. Krytox additive formulations showed small reductions in degradation rate. Krytox GPL-105, a higher viscosity version, yielded the least amount of degradation products. Both the silahydrocarbon and Pennzane 2001A showed no signs of lubricant degradation and had ample amounts of free oil at test conclusion.

  19. 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.

  20. On-Orbit Calibration of a Multi-Spectral Satellite Satellite Sensor Using a High Altitude Airborne Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Green, R. O.; Shimada, M.

    1996-01-01

    Earth-looking satellites must be calibrated in order to quantitatively measure and monitor components of land, water and atmosphere of the Earth system. The inevitable change in performance due to the stress of satellite launch requires that the calibration of a satellite sensor be established and validated on-orbit. A new approach to on-orbit satellite sensor calibration has been developed using the flight of a high altitude calibrated airborne imaging spectrometer below a multi-spectral satellite sensor.

  1. Control System and Flexible Satellite Interaction During Orbit Transfer Maneuver

    NASA Technical Reports Server (NTRS)

    daSilva, Adenilson Roberto; GadelhadeSouza, Luiz Carlos

    1998-01-01

    In this paper the interaction between the attitude control system and the flexible structure of an artificial satellite during orbit transfer maneuver has been investigated. The satellite was modeled by a rigid central body with one or more flexible appendages. The dynamics equations were obtained by Lagrangean approach. The flexible appendages were treated as clamped-free beam and its displacement was discretized by assumed- mode method. In order to transfer the satellite, a typical Hohmann transfer and a burn-coast-burn strategy were used and the attitude was controlled by an on-off controller. During transfer procedure a global analysis of satellite has been done, such as: performance of control system, influence of elastic response in control system, thruster firing frequency, fuel consumption and variation of orbital elements. In order to avoid the interaction with structure motion, a control system with bandwidth of one decade bellow the fundamental frequency was used. In the simulations the firing frequency was evaluated in an approximately way but kept below the fundamental frequency of the structure. The control system has kept the attitude below the specifications. As a result, the orbit transfer maneuvering has been done correctly without excessive excitation of flexible appendage.

  2. NASA Now: Orbital Mechanics: Earth Observing Satellites - Duration: 6 minutes, 3 seconds.

    NASA Video Gallery

    This NASA Now program is all about satellites and their orbits. Dr. James Gleason, project scientist for NPP, explains what it takes for a satellite to stay in orbit, why there are different types ...

  3. Characteristic of the Orbit of Quasi Zenith Satellite

    NASA Astrophysics Data System (ADS)

    Maeda, Hiroaki; Kawaguchi, Yoshihisa; Yasuda, Akio

    Quasi Zenith Satellite System is a satellite navigation system to serve over the whole area of the East Asia and the Oceania region. The ground trace of the satellite changes gradually due to the orbit perturbation caused by the earth gravity, moon, sun and solar radiation pressure. To study maintenance of the ground trace it was needed to know the characteristics of the orbit. In this paper we described the characteristics of the longitude of ascending node (LAN), the eccentricity (e) and the other parameters. The earth Non-Zonal term induces the harmful perturbation onto the semi major axis (a), which directly relates the longitude of ascending node (LAN) and the average longitude of the ground trace. The fluctuation of the eccentricity (e) is depend on right ascension of ascending node, and is not negligible. The orbit which has the right ascension of ascending node = 210deg is the most stable orbit. And we also suggest that it is important to control two parameters, the eccentricity and the semi major axis to maintain the ground trace. The maintenance interval should be from 6 months to 12 months.

  4. Galileo satellites measurement biases and orbit determination: first results

    NASA Astrophysics Data System (ADS)

    Perosanz, F.; Loyer, S.; Mercier, F.; Boulanger, C.; Capdeville, H.; Mezerette, A.

    2012-12-01

    Thanks to the IGS Multi-GNSS Experiment (M-GEX), signals from new GNSS satellites like Galileo are now available. CNES and IGN joined their efforts to contribute to the densification of this multi-GNSS global network through the REGINA project. However this network includes geodetic receivers from several manufacturers. For this reason we realized a dedicated test campaign to characterize the different receivers available in order to be able to process in a consistent way the data from the MGEX network. The test consisted in zero baseline measurements between receivers. Pseudo range as well as phase and wide-lane biases have been identified between Trimble, Leica, Javad and Septentrio receivers. Then the data from the global M-GEX tracking network have been processed for the Precise Orbit determination of the Galileo satellite. The strategy followed the one that the CNES-CLS IGS Analysis Center uses to compute hybrid GPS-GLONASS products. Since July 2012, Galileo data are processed and orbit solutions are routinely produced and evaluated. Pseudo-range and phase biases between receiver as well as inter-system biases have been quantified. We also demonstrated that a decimeter 3D-WRMS orbit accuracy of Galileo satellite orbit can be achieved even during the constellation deployment.

  5. Galileo satellites measurement biases and orbit determination : preliminary results

    NASA Astrophysics Data System (ADS)

    Perosanz, Felix; Loyer, Sylvain; Mercier, Flavien; Boulanger, Cyrille; Capdeville, Hugues; Mezerette, Adrien

    2013-04-01

    Thanks to the IGS Multi-GNSS Experiment (M-GEX), signals from new GNSS satellites like Galileo are now available. CNES and IGN joined their efforts to contribute to the densification of this multi-GNSS global network through the REGINA project. However this network includes geodetic receivers from several manufacturers. For this reason we realized a dedicated test campaign to characterize the different receivers available in order to be able to process in a consistent way the data from the MGEX network. The test consisted in zero baseline measurements between receivers. Pseudo range as well as phase and wide-lane biases have been identified between Trimble, Leica, Javad and Septentrio receivers. Then the data from the global M-GEX tracking network have been processed for the Precise Orbit determination (POD) of the Galileo satellite. The strategy followed the one that the CNES-CLS IGS Analysis Center uses to compute hybrid GPS-GLONASS products. Since July 2012, Galileo data are processed and orbit solutions are routinely produced and evaluated. Pseudo-range and phase biases between receiver as well as inter-system biases have been quantified. We also demonstrated that a sub-decimeter 3D-WRMS orbit accuracy of Galileo satellite orbit can be achieved even during the constellation deployment.

  6. Detectability of satellite fragmentations in highly eccentric orbits

    NASA Astrophysics Data System (ADS)

    Crowther, R.; Walker, R.; Dick, J. S. B.; Green, S. F.; Marchant, J.

    We consider the fragmentation of a satellite initially in a highly elliptical orbit (HEO) following hypervelocity collision with a debris object in low Earth orbit (LEO). The probability of such a collision is found to be small in the short term, but but the orbital lifetime for objects in HEO is much higher than for objects in circular orbits of similar perigee altitude. Thus the collision hazard they represent to LEO will continue in some cases for many hundreds of years. A 1.5m optical telescope equipped with fast read-out CCD arrays can detect debris of diameter ~1 cm in LEO. However, Molniya objects are detected much more efficiently using longer integration times and detecting them at high altitudes with a limiting size ~ cm at 20000km. The choice of observing site and telescope pointing direction can have a significant effect on the detection rate and size dependent selection effects.

  7. 47 CFR 25.282 - Orbit raising maneuvers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Orbit raising maneuvers. 25.282 Section 25.282... Technical Operations 25.282 Orbit raising maneuvers. A space station authorized to operate in the geostationary satellite orbit under this part is also authorized to transmit in connection with...

  8. 47 CFR 25.282 - Orbit raising maneuvers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Orbit raising maneuvers. 25.282 Section 25.282... Technical Operations 25.282 Orbit raising maneuvers. A space station authorized to operate in the geostationary satellite orbit under this part is also authorized to transmit in connection with...

  9. 47 CFR 25.282 - Orbit raising maneuvers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Orbit raising maneuvers. 25.282 Section 25.282... Technical Operations 25.282 Orbit raising maneuvers. A space station authorized to operate in the geostationary satellite orbit under this part is also authorized to transmit in connection with...

  10. 47 CFR 25.282 - Orbit raising maneuvers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Orbit raising maneuvers. 25.282 Section 25.282... Technical Operations 25.282 Orbit raising maneuvers. A space station authorized to operate in the geostationary satellite orbit under this part is also authorized to transmit in connection with...

  11. 47 CFR 25.282 - Orbit raising maneuvers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Orbit raising maneuvers. 25.282 Section 25.282... Technical Operations 25.282 Orbit raising maneuvers. A space station authorized to operate in the geostationary satellite orbit under this part is also authorized to transmit in connection with...

  12. Use of elliptical orbits for a Ka-band personal access satellite system

    NASA Technical Reports Server (NTRS)

    Motamedi, Masoud; Estabrook, Polly

    1990-01-01

    The use of satellites in elliptical orbits for a Ka-band personal communications system application designed to provide voice and data service within the continental U.S. is examined. The impact of these orbits on system parameters such as signal carrier-to-noise ratio, roundtrip delay, Doppler shift, and satellite antenna size is quantized for satellites in two elliptical orbits, the Molniya and the ACE orbits. The number of satellites necessary for continuous CONUS coverage has been determined for the satellites in these orbits. The increased system complexity brought about by the use of satellites at such altitudes is discussed.

  13. 47 CFR 25.259 - Time sharing between NOAA meteorological satellite systems and non-voice, non-geostationary...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... bands, the protection area for a NOAA satellite is the area on the Earth's surface in which the NOAA... protection area for a NOAA satellite is the area on the Earth's surface in which the NOAA satellite is in... telephone number so that claims of harmful interference into NOAA earth station users and other...

  14. 47 CFR 25.259 - Time sharing between NOAA meteorological satellite systems and non-voice, non-geostationary...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... bands, the protection area for a NOAA satellite is the area on the Earth's surface in which the NOAA... protection area for a NOAA satellite is the area on the Earth's surface in which the NOAA satellite is in... time sharing spectrum in the 137-138 MHz band must establish a 24-hour per day contact person...

  15. High-orbit satellite magnitude estimation using photometric measurement method

    NASA Astrophysics Data System (ADS)

    Zhang, Shixue

    2015-12-01

    The means to get the accurate high-orbit satellite magnitude can be significant in space target surveillance. This paper proposes a satellite photometric measurement method based on image processing. We calculate the satellite magnitude by comparing the output value of camera's CCD between the known fixed star and the satellite. We calculate the luminance value of a certain object on the acquired image using a background-removing method. According to the observation parameters such as azimuth, elevation, height and the situation of the telescope, we can draw the star map on the image, so we can get the real magnitude of a certain fixed star in the image. We derive a new method to calculate the magnitude value of a certain satellite according to the magnitude of the fixed star in the image. To guarantee the algorithm's stability, we evaluate the measurement precision of the method, and analysis the restrict condition in actual application. We have made plenty of experiment of our system using large telescope in satellite surveillance, and testify the correctness of the algorithm. The experimental result shows that the precision of the proposed algorithm in satellite magnitude measurement is 0.24mv, and this method can be generalized to other relative fields.

  16. The Orbits and Masses of Pluto's Satellites after New Horizons

    NASA Astrophysics Data System (ADS)

    Jacobson, Robert A.; Brozovic, Marina; Buie, Marc; Porter, Simon; Showalter, Mark; Spencer, John; Stern, S. Alan; Weaver, Harold; Young, Leslie; Ennico, Kimberly; Olkin, Cathy

    2015-11-01

    Brozović et al. (2015 Icarus 246, 317) reported on Pluto's mass and the masses and numerically integrated orbits of Pluto's satellites, Charon, Nix, Hydra, Kerberos, and Styx. These were determined via a fit to an extensive set of astrometric, mutual event, and stellar occultation observations over the time interval April 1965 to July 2012. The data set contained the Hubble Space Telescope (HST) observations of Charon relative to Pluto that were corrected for the Pluto center-of-figure center-of-light offset due to the Pluto albedo variations (Buie et al. 2012 AJ 144, 15). Also included were all of the available HST observations of Nix, Hydra, Kerberos, and Styx. For the New Horizons encounter with the Pluto system, the initial satellite ephemerides (PLU043) and the initial planet and satellite masses were taken from the Brozović et al. analysis. During the New Horizons approach, the ephemerides and masses were periodically updated along with the spacecraft trajectory by the New Horizons navigation team using imaging of the planet and satellites against the stellar background. In this work, we report on our post-flyby analysis of the masses and satellite orbits derived from a combination of the original PLU043 data set, the New Horizions imaging data, and HST observations acquired after 2012.

  17. Advanced Communications Technology Satellite Now Operating in an Inclined Orbit

    NASA Technical Reports Server (NTRS)

    Bauer, Robert A.

    1999-01-01

    The Advanced Communications Technology Satellite (ACTS) system has been modified to support operation in an inclined orbit that is virtually transparent to users, and plans are to continue this final phase of its operation through September 2000. The next 2 years of ACTS will provide a new opportunity for using the technologies that this system brought online over 5 years ago and that are still being used to resolve the technical issues that face NASA and the satellite industry in the area of seamless networking and interoperability with terrestrial systems. New goals for ACTS have been defined that align the program with recent changes in NASA and industry. ACTS will be used as a testbed to: Show how NASA and other Government agencies can use commercial systems for 1. future support of their operations Test, characterize, and resolve technical issues in using advanced communications 2. protocols such as asynchronous transfer mode (ATM) and transmission control protocol/Internet protocol (TCP/IP) over long latency links as found when interoperating satellites with terrestrial systems Evaluate narrow-spot-beam Ka-band satellite operation in an inclined orbit 3. Verify Ka-band satellite technologies since no other Ka-band system is yet 4. available in the United States

  18. 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.

  19. A method for capturing asteroids into earth satellite orbits

    NASA Astrophysics Data System (ADS)

    Ledkov, A. A.; Eismont, N. A.; Nazirov, R. R.; Boyarsky, M. N.

    2015-08-01

    At present, the capture of a suitable asteroid into an Earth satellite orbit is proposed as one of the methods for investigating asteroids within the framework of manned missions. Once the asteroid has been transferred to such an orbit, an expedition with the participation of astronauts is planned to the asteroid surface, where research is carried out and asteroid rock samples are selected and subsequently delivered to the Earth. It is in this way that the American Keck project is described at the current planning and preliminary design stage. In this paper, we solve the capture problem by a method alternative to that planned in the Keck project.

  20. 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.

  1. The accuracy of orbit estimation for the low-orbit satellites LARETS and WESTPAC

    NASA Astrophysics Data System (ADS)

    Rutkowska, Milena

    The LARETS satellite was launched on September 26, 2004, into a circular orbit at an altitude of 690 km and with an inclination of 98.2°. This mission is a successor to the WESTPAC satellite which was launched to an altitude of 835 km six years before. The study is based on the observations taken by the global network of laser stations during the period from December 30, 2003 to March 17, 2004 for LARETS. This study is aimed at the precise orbit computation of LARETS. The experience acquired during the orbit estimation of WESTPAC was applied to the orbit investigation of LARETS. The WESTPAC was merely used for reference and initial parameters of the force model [Rutkowska, M., Noomenn, R., Global orbit analysis of the satellite WESTPAC, Adv. Space Res., 30(2), 265-270, 2002]. The orbit of LARETS was estimated with an rms-of-fit to the SLR measurements of 3.9 cm, using the following computation model: the CSR TEG-4 gravity field up to degree and order (200,200), the Ray tide model, the MSIS86 model for atmospheric density [Hedin, A.E., MSIS-86 Thermospheric Model, J. Geophys. Res., 92 (A5), 4649-4662, 1987], and the solution of 8-hourly CD-values. It has been verified that the modeling of the gravity field up to degree and order (100,100) which gives the same rms-of-fit value. Estimated orbits for both satellites are compared to each other in Fig. 2. All computations are performed with the NASA program GEODYN II [Eddy, W.F, McCarthy, J.J., Pavlis, D.E., Marshall, J.A., Luthce, S.B., Tsaoussi, L.S., GEODYN II System Operations Manual, vol. 1-5, ST System Corp., Lanham MD, USA, 1990].

  2. Astrometry and Orbits of the Inner Satellites of Neptune

    NASA Astrophysics Data System (ADS)

    Pascu, D.; Rohde, J. R.; Seidelmann, P. K.; Wells, E. N.; Hershey, J. L.; Zellner, B. H.; Storrs, A. D.; Currie, D. G.; Bosh, A. S.

    1999-09-01

    We have obtained 39 HST (PC2) images of Neptune, Triton and inner moons in three HST orbits: two on 3 July, one on 6 July 1997. Of the six inner satellites discovered by Voyager 2, the four outer ones were recovered, as expected, and near their ephemeris positions. The two inner satellites were too faint and close to the planet for detection. The planet and all satellites were centroided with a Gaussian model using only the unsaturated portions of the images. The bright halo near the planet was also modelled for the faint satellites. The centroiding precision for Neptune and Triton was less than 1 mas, while that for the faintest satellites, embedded in the planetary halo, as high as 15 mas. After a correction for geometric distortion was applied, the scale and orientation were calibrated for each frame using the JPL ephemeris of Triton relative to Neptune. Two results of the astrometry were; a mean scale for PC2 of 0.045542 arcsec/pix, smaller by 1 part in 1900 than that determined from our astrometry in the Uranian system, and an orientation zero point correction dependent on the filter used. In the orbital analysis, only corrections to the mean daily motions, given by Owen et al. (1991, AJ 101, 1511) for the four faint satellites, were made. Neptune was taken as the coordinate zero point, and separate solutions made in separation and position angle, as well as combined solutions. All mean motion corrections were well below the quoted mean errors of the starting values. The separation and position angle solutions were in agreement for the three faintest satellites, but were in disagreement for Proteus, despite the 6 mas mean residual after solution. The cause for this discrepancy is being investigated. The corrected mean motions, resulting from these observations, are expected to provide ephemeris predictions accurate to 100 mas throughout the next century.

  3. 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.

  4. 47 CFR 25.146 - Licensing and operating rules for the non-geostationary satellite orbit Fixed-Satellite Service...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-density, in the space-to-Earth direction, (EPFD down) limits. (i) Provide a set of power flux-density (PFD) masks, on the surface of the Earth, for each space station in the NGSO FSS system. The PFD masks shall.... (2) Single-entry additional operational equivalent power flux-density, in the...

  5. Orbital Perturbations of the Galilean Satellites during Planetary Encounters

    NASA Astrophysics Data System (ADS)

    Deienno, Rogerio; Nesvorn, David; Vokrouhlick, 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 Nesvorn & 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 Nesvorn & 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.

  6. Orbital perturbations of the Galilean satellites during planetary encounters

    SciTech Connect

    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 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.

  7. 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 3.5W. 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.


  8. 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.

  9. 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.

    2015-11-01

    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 μm 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 biases 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 biases 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 and biases. 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 related to the atmospheric component of the water cycle.

  10. Laser beaming demonstrations to high-orbit satellites

    NASA Astrophysics Data System (ADS)

    Lipinski, Ronald J.; Meister, Dorothy C.; Tucker, Steve D.; Fugate, Robert Q.; Leatherman, Phillip; Maes, Carl F.; Lange, W. Joseph; Cowan, William D.; Meulenberg, Andrew; Cleis, Richard A.; Spinhirne, James M.; Ruane, Raymond E.; Michie, Robert B.; Vonderhaar, Donald F.

    1994-05-01

    A team of Phillips Laboratory, COMSAT Laboratories, and Sandia National Laboratories plans to demonstrate state-of-the-art 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. We 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 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 is especially challenging because the retro-reflectors 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 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/m2 on orbit is needed for this demonstration.

  11. An Intensive Research of Satellite Orbit Theory and Application in Orbit Determination, Forecast and Parameter Estimation

    NASA Astrophysics Data System (ADS)

    Tang, J. S.

    2011-03-01

    It has been over half a century since the launch of the first artificial satellite Sputnik in 1957, which marks the beginning of the Space Age. During the past 50 years, with the development and innovations in various fields and technologies, satellite application has grown more and more intensive and extensive. This thesis is based on three major research projects which the author joined in. These representative projects cover main aspects of satellite orbit theory and application of precise orbit determination (POD), and also show major research methods and important applications in orbit dynamics. Chapter 1 is an in-depth research on analytical theory of satellite orbits. This research utilizes general transformation theory to acquire high-order analytical solutions when mean-element method is not applicable. These solutions can be used in guidance and control or rapid orbit forecast within the accuracy of 10-6. We also discuss other major perturbations, each of which is considered with improved models, in pursuit of both convenience and accuracy especially when old models are hardly applicable. Chapter 2 is POD research based on observations. Assuming a priori force model and estimation algorithm have reached their accuracy limits, we introduce empirical forces to Shenzhou-type orbit in order to compensate possible unmodeled or mismodeled perturbations. Residuals are analyzed first and only empirical force models with actual physical background are considered. This not only enhances a posteriori POD accuracy, but also considerably improves the accuracy of orbit forecast. This chapter also contains theoretical discussions on modeling of empirical forces, computation of partial derivatives and propagation of various errors. Error propagation helps to better evaluate orbital accuracy in future missions. Chapter 3 is an application of POD in space geodesy. GRACE satellites are used to obtain Antarctic temporal gravity field between 2004 and 2007. Various changes from traditional methods are implemented to better represent the regional temporal gravity field in this work. As a thesis in astrodynamics, this chapter will concentrate on orbit problems and estimation approaches. Although most details in geophysics are skipped, gravity field solutions will be displayed and the preliminary images of Antarctic mass flux will be revealed. These researches are summarized but not concluded in this thesis. Many problems have been left in all the aspects mentioned in this thesis and need to be studied in future researches, not to mention that the fast developing space technology keeps redefining our traditional knowledge with new concepts and elements. So future work and directions will be discussed at the end of the thesis, expecting further progress upon the present achievements.

  12. Tracking target objects orbiting earth using satellite-based telescopes

    DOEpatents

    De Vries, Willem H; Olivier, Scot S; Pertica, Alexander J

    2014-10-14

    A system for tracking objects that are in earth orbit via a constellation or network of satellites having imaging devices is provided. An object tracking system includes a ground controller and, for each satellite in the constellation, an onboard controller. The ground controller receives ephemeris information for a target object and directs that ephemeris information be transmitted to the satellites. Each onboard controller receives ephemeris information for a target object, collects images of the target object based on the expected location of the target object at an expected time, identifies actual locations of the target object from the collected images, and identifies a next expected location at a next expected time based on the identified actual locations of the target object. The onboard controller processes the collected image to identify the actual location of the target object and transmits the actual location information to the ground controller.

  13. 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.

  14. 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.

  15. Spatially resolving methane emissions in California: constraints from the CalNex aircraft campaign and from present (GOSAT, TES) and future (TROPOMI, geostationary) satellite observations

    NASA Astrophysics Data System (ADS)

    Wecht, K. J.; Jacob, D. J.; Sulprizio, M. P.; Santoni, G. W.; Wofsy, S. C.; Parker, R.; Bösch, H.; Worden, J.

    2014-08-01

    We apply a continental-scale inverse modeling system for North America based on the GEOS-Chem model to optimize California methane emissions at 1/2° × 2/3° horizontal resolution using atmospheric observations from the CalNex aircraft campaign (May-June 2010) and from satellites. Inversion of the CalNex data yields a best estimate for total California methane emissions of 2.86 ± 0.21 Tg a-1, compared with 1.92 Tg a-1 in the EDGAR v4.2 emission inventory used as a priori and 1.51 Tg a-1 in the California Air Resources Board (CARB) inventory used for state regulations of greenhouse gas emissions. These results are consistent with a previous Lagrangian inversion of the CalNex data. Our inversion provides 12 independent pieces of information to constrain the geographical distribution of emissions within California. Attribution to individual source types indicates dominant contributions to emissions from landfills/wastewater (1.1 Tg a-1), livestock (0.87 Tg a-1), and gas/oil (0.64 Tg a-1). EDGAR v4.2 underestimates emissions from livestock, while CARB underestimates emissions from landfills/wastewater and gas/oil. Current satellite observations from GOSAT can constrain methane emissions in the Los Angeles Basin but are too sparse to constrain emissions quantitatively elsewhere in California (they can still be qualitatively useful to diagnose inventory biases). Los Angeles Basin emissions derived from CalNex and GOSAT inversions are 0.42 ± 0.08 and 0.31 ± 0.08 Tg a-1 that the future TROPOMI satellite instrument (2015 launch) will be able to constrain California methane emissions at a detail comparable to the CalNex aircraft campaign. Geostationary satellite observations offer even greater potential for constraining methane emissions in the future.

  16. Spatially resolving methane emissions in California: constraints from the CalNex aircraft campaign and from present (GOSAT, TES) and future (TROPOMI, geostationary) satellite observations

    NASA Astrophysics Data System (ADS)

    Wecht, K. J.; Jacob, D. J.; Sulprizio, M. P.; Santoni, G. W.; Wofsy, S. C.; Parker, R.; Bösch, H.; Worden, J.

    2014-02-01

    We apply a continental-scale inverse modeling system for North America based on the GEOS-Chem model to optimize California methane emissions at 1/2° × 2/3° horizontal resolution using atmospheric observations from the CalNex aircraft campaign (May-June 2010) and from satellites. Inversion of the CalNex data yields a best estimate for total California methane emissions of 2.86 ± 0.21 Tg yr-1, compared with 1.92 Tg yr-1 in the EDGAR v4.2 emission inventory used as a priori and 1.51 Tg yr-1 in the California Air Resources Board (CARB) inventory used for state regulations of greenhouse gas emissions. These results are consistent with a previous Lagrangian inversion of the CalNex data. Our inversion provides 12 independent pieces of information to constrain the geographical distribution of emissions within California. Attribution to individual source types indicates dominant contributions to emissions from landfills/wastewater (1.1 Tg yr-1), livestock (0.87 Tg yr-1), and gas/oil (0.64 Tg yr-1). EDGAR v4.2 underestimates emissions from livestock while CARB underestimates emissions from landfills/wastewater and gas/oil. Current satellite observations from GOSAT can constrain methane emissions in the Los Angeles Basin but are too sparse to constrain emissions quantitatively elsewhere in California (they can still be qualitatively useful to diagnose inventory biases). Los Angeles Basin emissions derived from CalNex and GOSAT inversions are 0.42 ± 0.08 and 0.31 ± 0.08, respectively. An observation system simulation experiment (OSSE) shows that the future TROPOMI satellite instrument (2015 launch) will be able to constrain California methane emissions at a detail comparable to the CalNex aircraft campaign. Geostationary satellite observations offer even greater potential for constraining methane emissions in the future.

  17. Impacts of geostationary satellite measurements on CO forecasting: An observing system simulation experiment with GEOS-Chem/LETKF data assimilation system

    NASA Astrophysics Data System (ADS)

    Yumimoto, Keiya

    2013-08-01

    We developed a chemical data assimilation system based on the GEOS-Chem global chemical transport model (CTM) and an ensemble-based data assimilation method, and performed an observing system simulation experiment (OSSE) to evaluate the impact of geostationary (GEO) satellite data obtained with a multi-spectral (thermal infrared (TIR) and near infrared (NIR)) sensor on air quality forecasting in East Asia. Initial conditions determined by assimilation of the three observation sets improved the forecasting of trans-boundary CO outflow. The performance of GEO satellite with TIR sensor (GEO-TIR) was better than that of LEO satellite with TIR sensor (LEO-TIR). However, in Seoul district (the Korean Peninsula) and Northern Kyushu (western Japan), the positive impact of the wider coverage and higher frequency of GEO disappeared when the forecast time was longer than 48 h. GEO satellite with NIR and TIR sensor (GEO-NIR + TIR) improved the forecast most, reducing the root mean square difference (RMSD), normalized mean bias, and normalized mean difference by more than 20% even for a forecast time longer than 48 h. Using the LEO-TIR result as a benchmark, we evaluated the ability of GEO-NIR + TIR to improve the forecast. The 60-h CO forecasting performances of GEO-TIR and GEO-NIR + TIR were about 30% and 120% better, respectively, than that of LEO-TIR. The wider coverage and higher frequency of GEO therefore improved the RMSD by 30%, and the higher sensitivity in the lower troposphere of NIR + TIR improved it by an additional 90%. Thus, the higher sensitivity in the lower troposphere of NIR + TIR as well as the wider coverage and higher frequency of GEO had a notably positive impact on the forecasting of trans-boundary pollutants over East Asia.

  18. The orbits and masses of satellites of Pluto

    NASA Astrophysics Data System (ADS)

    Brozović, Marina; Showalter, Mark R.; Jacobson, Robert A.; Buie, Marc W.

    2015-01-01

    We present the numerically integrated orbits of Pluto's satellites. The orbits have been fit to a data set that includes Earth-based and Hubble Space Telescope (HST) astrometry of Charon, Nix, Hydra, Kerberos, and Styx, as well as the lightcurves from the Pluto-Charon mutual events. We also report new, 2010-2012 HST astrometry of all satellites including recently discovered Styx plus a pre-discovery detection of Kerberos in 2006. Pluto-relative data sets have been corrected for the center-of-light vs. center-of-mass offsets with the Pluto albedo model. The results are summarized in terms of the postfit residuals, state vectors, and mean orbital elements. Orbits of Charon, Styx, Nix, and Kerberos are nearly circular, while Hydra's shows a small eccentricity. All satellites are in near-resonance conditions, but we did not uncover any resonant arguments. Our model yields 975.5 ± 1.5 km3 s-2, 869.6 ± 1.8 km3 s-2, and 105.9 ± 1.0 km3 s-2 for the system's, Pluto's, and Charon's GM values. The uncertainties reflect both systematic and random measurement errors. The GM values imply a bulk density of 1.89 ± 0.06 g cm-3 for Pluto and 1.72 ± 0.02 g cm-3 for Charon. We also obtain GMNix = 0.0030 ± 0.0027 km3 s-2 GMHydra = 0.0032 ± 0.0028 km3 s-2, GMKerberos = 0.0011 ± 0.0006 km3 s-2, and an upper bound on Styx's GM of 0.0010 km3 s-2. The 1σ errors are based on the formal covariance from the fit and they reflect only measurement errors. In-orbit (or along the track), radial, and out-of-plane orbital uncertainties at the time of New Horizons encounter are on the order of few tens of km or less for Charon, Nix, and Hydra. Kerberos and Styx have their largest uncertainty component of ∼140 km and ∼500 km respectively in the in-orbit direction.

  19. Gravity and Tide Parameters Determined from Satellite and Spacecraft Orbits

    NASA Astrophysics Data System (ADS)

    Jacobson, Robert A.

    2015-05-01

    As part of our work on the development of the Jovian and Saturnian satellite ephemerides to support the Juno and Cassini missions, we determined a number of planetary system gravity parameters. This work did not take into account tidal forces. In fact, we saw no obvious observational evidence of tidal effects on the satellite or spacecraft orbits. However, Lainey et al. (2009 Nature 459, 957) and Lainey et. al (2012 Astrophys. J. 752, 14) have published investigations of tidal effects in the Jovian and Saturnian systems, respectively. Consequently, we have begun a re-examination of our ephemeris work that includes a model for tides raised on the planet by the satellites as well as tides raised on the satellites by the planet. In this paper we briefly review the observations used in our ephemeris production; they include astrometry from the late 1800s to 2014, mutual events, eclipses, occultatons, and data acquired by the Pioneer, Voyager, Ulysses, Cassini, Galileo, and New Horizons spacecraft. We summarize the gravity parameter values found from our original analyses. Next we discuss our tidal acceleration model and its impact on the gravity parameter determination. We conclude with preliminary results found when the reprocessing of the observations includes tidal forces acting on the satellites and spacecraft.

  20. A sensitivity study for the calibration of hyperspectral spectrometer on board the geostationary multipurpose satellite of Korea

    NASA Astrophysics Data System (ADS)

    Ahn, Myoung-Hwan; Kang, Mina; Liu, Xiong; Kim, Jhoon

    2015-06-01

    A spectral calibration algorithm for the hyperspectral geostationary environmental monitoring spectrometer (GEMS) onboard GEO-KOMPSAT-2B (GK-2B) planned to launch in 2019 has been developed. Although spectral registration for the CCD detector is done by the optical parameters prepared during the ground test of the instrument, the algorithm is applied for the improved spectral accuracy. The prototype algorithm is based on the best fitting of the measured spectrum to the known high resolution reference spectrum such as the solar irradiance. To characterize the prototype algorithm, a series of sensitivity tests for various spectral parameters, such as squeeze, shift, spectral response function, and reference solar spectrum, has been performed. The prototype algorithm shows a minimal sensitive to the uncertainties associated with several parameters such as squeeze, shift, or spectral band. However, the algorithm performance degrades by an order if the spectral response function including its shape has uncertainty. Thus, it is recommended to measure the spectral response function at the ground test as accurately as possible. Furthermore, the prototype algorithm is also highly sensitive to the used reference solar spectrum, which needs further investigation.

  1. 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.

  2. A Low Earth Orbit satellite marine communication system demonstration

    NASA Technical Reports Server (NTRS)

    Elms, T. Keith; Butt, Kenneth A.; Asmus, Ken W.

    1995-01-01

    An application of Low Earth Orbit (LEO) satellite communications technology was investigated during a joint Canadian/American scientific expedition to the north pole in the summer of 1994. The Canadian ice breaker involved, was equipped with a store-and-forward LEO satellite terminal which was linked to a ground station in St. John's, Newfoundland, via the near-polar-orbiting satellite, HealthSat-l. The objective was to evaluate the performance of such a system while providing an alternate means of communications in the far north. The system performed well, given its inherent limitations. All 151 attempts to send data files to the ship were successful. Only two (2) of the 35 attempts to send files from the ship were unsuccessful. The files ranged in size from 0.1 to 60 Kbytes. In the high arctic, above 80 deg north, this system often provided the only practical means of data communications. This experiment demonstrated the potential of such a system for not-real-time communications with remote and/or mobile stations, and highlighted the many issues involved. This paper describes the project objectives, system configuration and experimental procedure used, related technical issues, trial results, future work, and conclusions.

  3. Geostationary platform systems concepts definition study. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The results of a geostationary platform concept analysis are summarized. Mission and payloads definition, concept selection, the requirements of an experimental platform, supporting research and technology, and the Space Transportation System interface requirements are addressed. It is concluded that platforms represent a logical extension of current trends toward larger, more complex, multifrequency satellites. Geostationary platforms offer significant cost savings compared to individual satellites, with the majority of these economies being realized with single Shuttle launched platforms. Further cost savings can be realized, however, by having larger platforms. Platforms accommodating communications equipment that operates at multiple frequencies and which provide larger scale frequency reuse through the use of large aperture multibeam antennas and onboard switching maximize the useful capacity of the orbital arc and frequency spectrum. Projections of market demand indicate that such conservation measures are clearly essential if orderly growth is to be provided for. In addition, it is pointed out that a NASA experimental platform is required to demonstrate the technologies necessary for operational geostationary platforms of the 1990's.

  4. Orbit Determination of the SELENE Satellites Using Multi-Satellite Data Types and Evaluation of SELENE Gravity Field Models

    NASA Technical Reports Server (NTRS)

    Goossens, S.; Matsumoto, K.; Noda, H.; Araki, H.; Rowlands, D. D.; Lemoine, F. G.

    2011-01-01

    The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis. It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an average level of 18m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the SELENE models, depending on whether l-day data overlaps or I-day predictions are used.

  5. Evaluation of ISCCP multisatellite radiance calibration for geostationary imager visible channels using the moon

    USGS Publications Warehouse

    Stone, Thomas C.; William B. Rossow; Joseph Ferrier; Laura M. Hinkelman

    2013-01-01

    Since 1983, the International Satellite Cloud Climatology Project (ISCCP) has collected Earth radiance data from the succession of geostationary and polar-orbiting meteorological satellites operated by weather agencies worldwide. Meeting the ISCCP goals of global coverage and decade-length time scales requires consistent and stable calibration of the participating satellites. For the geostationary imager visible channels, ISCCP calibration provides regular periodic updates from regressions of radiances measured from coincident and collocated observations taken by Advanced Very High Resolution Radiometer instruments. As an independent check of the temporal stability and intersatellite consistency of ISCCP calibrations, we have applied lunar calibration techniques to geostationary imager visible channels using images of the Moon found in the ISCCP data archive. Lunar calibration enables using the reflected light from the Moon as a stable and consistent radiometric reference. Although the technique has general applicability, limitations of the archived image data have restricted the current study to Geostationary Operational Environmental Satellite and Geostationary Meteorological Satellite series. The results of this lunar analysis confirm that ISCCP calibration exhibits negligible temporal trends in sensor response but have revealed apparent relative biases between the satellites at various levels. However, these biases amount to differences of only a few percent in measured absolute reflectances. Since the lunar analysis examines only the lower end of the radiance range, the results suggest that the ISCCP calibration regression approach does not precisely determine the intercept or the zero-radiance response level. We discuss the impact of these findings on the development of consistent calibration for multisatellite global data sets.

  6. 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.

  7. Alternative packet switch architectures for a 30/20 GHz FDMA/TDMA geostationary communication satellite network

    NASA Technical Reports Server (NTRS)

    Stehle, Roy; Ogier, Richard G.

    1995-01-01

    This study has investigated alternatives for realizing a packet-based network switch for deployment on a communication satellite. The emphasis was on the avoidance of contention problems that can occur due to the simultaneous arrival of an excessive number of packets destined for the same downlink dwell. The study was to look ahead, beyond the current Advanced Communications Technology Satellite (ACTS) capability, to the next generation of satellites. The study has not been limited by currently available technology, but has used university and commercial research efforts as a basis for designs that can be readily constructed and launched within the next five years. Tradeoffs in memory requirement, power requirement, and architecture have been considered as a part of our study.

  8. 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.

  9. 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.

  10. Laser beaming demonstrations to high-orbit satellites

    SciTech Connect

    Lipinski, R.J.; Meister, D.C.; Tucker, S.

    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.

  11. Laser beaming demonstrations to high-orbit satellites

    SciTech Connect

    Lipinski, R.J.; Meister, D.C.; Tucker, S.

    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.

  12. Computer simulation results of attitude estimation of earth orbiting satellites

    NASA Technical Reports Server (NTRS)

    Kou, S. R.

    1976-01-01

    Computer simulation results of attitude estimation of Earth-orbiting satellites (including Space Telescope) subjected to environmental disturbances and noises are presented. Decomposed linear recursive filter and Kalman filter were used as estimation tools. Six programs were developed for this simulation, and all were written in the basic language and were run on HP 9830A and HP 9866A computers. Simulation results show that a decomposed linear recursive filter is accurate in estimation and fast in response time. Furthermore, for higher order systems, this filter has computational advantages (i.e., less integration errors and roundoff errors) over a Kalman filter.

  13. 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.

  14. 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.

  15. 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 S.

    1994-01-01

    The thrust of the proposed effort under this contract is aimed at improving techniques to track water vapor data in sequences of imagery from geostationary satellites. In regards to this task, significant testing, evaluation, and progress was accomplished during this period. Sets of winds derived from Meteosat data were routinely produced during Atlantic hurricane events in the 1993 season. These wind sets were delivered via Internet in real time to the Hurricane Research Division in Miami for their evaluation in a track forecast model. For eighteen cases in which 72-hour forecasts were produced, thirteen resulted in track forecast improvements (some quite significant). In addition, quality-controlled Meteosat water vapor winds produced by NESDIS were validated against rawinsondes, yielding an 8 m/s RMS. This figure is comparable to upper-level cloud drift wind accuracies. Given the complementary horizontal coverage in cloud-free areas, we believe that water vapor vectors can supplement cloud-drift wind information to provide good full-disk coverage of the upper tropospheric flow. The impact of these winds on numerical analysis and forecasts will be tested in the next reporting period.

  16. 47 CFR 25.142 - Licensing provisions for the non-voice, non-geostationary mobile-satellite service.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... density produced at the Earth's surface by each space station of their system in the frequency bands 137...), as calculated for a fixed point on the Earth's surface in the plane of the space station's orbit... coordinate with NTIA/IRAC with regard to the frequencies to be shared by those earth stations of...

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

    NASA Technical Reports Server (NTRS)

    Musen, P.

    1975-01-01

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

  18. Assimilation of next generation geostationary aerosol optical depth retrievals to improve air quality simulations

    NASA Astrophysics Data System (ADS)

    Saide, Pablo E.; Kim, Jhoon; Song, Chul H.; Choi, Myungje; Cheng, Yafang; Carmichael, Gregory R.

    2014-12-01

    Planned geostationary satellites will provide aerosol optical depth (AOD) retrievals at high temporal and spatial resolution which will be incorporated into current assimilation systems that use low-Earth orbiting (e.g., Moderate Resolution Imaging Spectroradiometer (MODIS)) AOD. The impacts of such additions are explored in a real case scenario using AOD from the Geostationary Ocean Color Imager (GOCI) on board of the Communication, Ocean, and Meteorology Satellite, a geostationary satellite observing northeast Asia. The addition of GOCI AOD into the assimilation system generated positive impacts, which were found to be substantial in comparison to only assimilating MODIS AOD. We found that GOCI AOD can help significantly to improve surface air quality simulations in Korea for dust, biomass burning smoke, and anthropogenic pollution episodes when the model represents the extent of the pollution episodes and retrievals are not contaminated by clouds. We anticipate future geostationary missions to considerably contribute to air quality forecasting and provide better reanalyses for health assessments and climate studies.

  19. Elliptic Orbit Constellations for Regional Communication and Molniya-Zond Satellite Constellation

    NASA Astrophysics Data System (ADS)

    Doniants, V. N.; Ulybyshev, Yu. P.

    2002-01-01

    Satellite constellations for regional communication in north hemisphere based on elliptic orbits with critical inclination and perigee in south hemisphere are considered. Several constellations for continuous zonal coverage are proposed. The constellations consist of 4-8 satellites which are arranged in 2-3 orbital planes with symmetrically placing around the equator. A coverage statistics and comparative analysis are presented. A geometry of continuous coverage for a latitude band is described. It is found, that a more suitable constellation for appropriate latitude band and minimal elevation angle can be choosed among the constellations with the same total number of satellites, equal orbits and various phasing angles between satellites of adjacent orbits. Problems of coverage area expansion due to launch of additional satellites and/or orbit change is considered. The new regional satellite communication system MOLNIYA-ZOND with such type of satellite constellation is shortly described.

  20. A small satellite constellation for continuous coverage of mid-low earth latitudes

    NASA Astrophysics Data System (ADS)

    Ortore, Emiliano; Ulivieri, Carlo

    2008-06-01

    When located on a geostationary orbit, a satellite keeps a steady position with respect to a generic point on the Earth's surface and this characteristic allows for important advantages. A continuous longitudinal coverage of the Earth's surface (higher latitudes excluded) is a result of using a three geo-satellite constellation. Nevertheless, there are also several drawbacks related to the geostationary orbit employment. The need to consider alternative satellite constellations has begun to arise from these disadvantages; these constellations, in spite of having very similar characteristics to the geostationary system, are able to overcome the complexity, the costs and the launching site problems connected with a geostationary satellite. For equatorial orbits, the Four-Leaf Clover System represents a profitable alternative compared to the traditional geostationary system. As far as high Earth latitudes are concerned, there are different operational constellations, such as Molniya and Tundra, capable of ensuring the continuous coverage of a region and generally taking orbits with a critical inclination into account (63.43 deg). The aim of this paper is to demonstrate that it is possible to create a satellite constellation capable of ensuring a continuous coverage of mid-low Earth latitudes. After a general study of the orbits employed to date, followed by a general graphical representation, a constellation of eight small satellites in multi-synchronous orbits makes the achievement of this paper's aim possible. Several possibilities for application follow, both for telecommunications and remote sensing missions.

  1. Constant Orbital Momentum Equilibrium Trajectories of a Gyrostat-Satellite

    NASA Astrophysics Data System (ADS)

    VanDyke, Matthew Clark

    This dissertation investigates attitude transition maneuvers of a gyrosat-satellite between relative equilibria. The primary challenge in transitioning between relative equilibria is the proper adjustment of the system angular momentum so that upon completing the transition maneuver the gyrostat-satellite will satisfy all the requirements for a relative equilibrium. The system angular momentum is a function of the attitude trajectory taken during the transition maneuver. A new concept, the constant orbital momentum equilibrium trajectory or COMET, is introduced as a means to a straight-forward solution to a subset of the possible transitions between relative equilbria. COMETs are a class of paths in SO(3) that a gyrostat-satellite may travel along that maintain a constant system angular momentum. The primary contributions of this dissertation are the introduction and analysis of COMETs and their application to the problem of transitioning a gyrostat-satellite between two relative equilibria. The current work introduces, defines, and analyzes COMETs in detail. The requirements for a path in SO(3) to be a COMET are defined. It is shown via example that COMETs are closed-curves in SO(3). Visualizations of families of COMETs are presented and discussed in detail. A subset of COMETs are shown to contain critical points that represent isolated relative equilibrium attitudes or furcations of the COMET. The problem of transitioning between two relative equilibria is split into the sub-problems of transitioning between relative equilibria on the same COMET and transitioning between relative equilibria on different COMETs. For transitions between relative equilibria on the same COMET, an open-loop control law is developed that drives a gyrostat-satellite along the COMET until the target relative equilibrium is reached. For transitions between relative equilibria on different COMETs, an open-loop control law is developed that transfers a gyrostat-satellite from the initial relative equilibrium to a relative equilibrium that resides on the same COMET as the target relative equilbrium. Acquisition of the target relative equilibrium is then accomplished via the application of the open-loop control law for transitions between relative equilibria on the same COMET. The results of numeric simulations of gyrostat-satellites executing these transitions are presented.

  2. Observation of global electromagnetic resonances by low- orbiting satellites

    NASA Astrophysics Data System (ADS)

    Surkov, V. V.

    2016-02-01

    Penetration of Schumann resonances energy from the Earth-ionosphere resonance cavity into the circumterrestrial space is examined. This study focuses on estimates of Alfvén wave amplitude and spectra in the frequency range of 7-50 Hz which can be observed by low-orbiting satellites. Differences in Schumann resonances observation conditions between the nighttime and sunlit sides of the ionosphere are analyzed. Particular emphasis has been placed on the ionospheric Alfvén resonator (IAR) excited by both global thunderstorm activity and individual lightning discharges. IAR spectra in the frequency range of 0.5-10 Hz are calculated for ionospheric altitudes. The calculated spectral amplitudes of IAR and Schumann resonances are compatible with C/NOFS satellite observations. To explain a shift of IAR resonant frequencies observed during C/NOFS satellite passage through terminator region, the IAR model is developed in which an interference of Alfvén waves reflected from the ionospheric E-layer and the IAR upper boundary is taken into account.

  3. 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.

  4. Autonomous Low Earth Orbit Satellite and Orbital Debris Tracking Using Mid Aperture COTS Optical Trackers

    NASA Astrophysics Data System (ADS)

    Ehrhorn, B.; Azari, D.

    Low Earth Orbit (LEO) and Orbital Debris tracking have become considerably important with regard to Space Situational Awareness (SSA). This paper discusses the capabilities of autonomous LEO and Orbital Debris Tracking Systems using commercially available (mid aperture 20-24 inch) telescopes, tracking gimbals, and CCD imagers. RC Optical Systems has been developing autonomous satellite trackers that allow for unattended acquisition, imaging, and orbital determination of LEOs using low cost COTS equipment. The test setup from which we are gathering data consists of an RC Optical Systems Professional Series Elevation over Azimuth Gimbal with field de-rotation, RC Optical Systems 20 inch Ritchey-Chretien Telescope coupled to an e2v CCD42-40 CCD array, and 77mm f/4 tracking lens coupled to a KAF-0402ME CCD array. Central to success of LEO acquisition and open loop tracking is accurate modeling of Gimbal and telescope misalignments and flexures. Using pro-TPoint and a simple automated mapping routine we have modeled our primary telescope to achieve pointing and tracking accuracies within a population standard deviation of 1.3 arc-sec (which is 1.1 arc-sec RMS). Once modeled, a mobile system can easily and quickly be calibrated to the sky using a simple 6-10 star map to solve for axis tilt and collimation coefficients. Acquisition of LEO satellites is accomplished through the use of a wide field imager. Using a 77mm f/4 lens and 765 x 510 x 9mu CCD array yields a 1.28 x 0.85 degree field of view in our test setup. Accurate boresite within the acquisition array is maintained throughout the full range of motion through differential tpoint modeling of the main and acquisition imagers. Satellite identification is accomplished by detecting a stationary centroid as a point source and differentiating from the background of streaked stars in a single frame. We found 100% detection rate of LEO with radar cross sections (RCS) of > 0.5 meter*meter within the acquisition array, and approximately 90% within 0.25 degrees of center. Tests of open loop tracking revealed a vast majority of satellites remain within the main detector area of 0.19 x 0.19 degrees after initial centering. Once acquired, the satellite is centered within the main imager via automated adjustment of the epoch and inclination using non-linear least square fit. Thereafter, real time satellite position is sequentially determined and recorded using the main imaging array. Real time determination of the SGP4 Keplerian elements are solved using non-linear least squares regression. The tracking propagator is periodically updated to reflect the solved Keplerian elements in order to maintain the satellite position near image center. These processes are accomplished without the need for user intervention. Unattended fully autonomous LEO satellite tracking and orbital determination simply requires scheduling of appropriate targets and scripted command of the tracking system.

  5. 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.

  6. 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.

  7. Non-gravitational effect on the relay satellite and the lunar orbiter of SELENE.

    NASA Astrophysics Data System (ADS)

    Toshihiro, K.

    In order to calculate the lunar gravitational coefficients from the orbits of lunar orbiters, it is very important to assess the non-gravitational effects on their orbits. In the cases of the relay satellite and the lunar orbiter of SELENE, a Japanese lunar mission which will start in 2003, solar radiation pressure is the largest non-gravitational force. The author presents a new model describing the solar radiation pressure on the relay satellite of SELENE.

  8. Launch vehicles for communications satellites

    NASA Technical Reports Server (NTRS)

    Mahon, J. B.

    1982-01-01

    After giving brief development histories of the Delta and the Atlas Centaur launch vehicles, attention is given to the operational characteristics of the ascent, parking orbit, transfer orbit, and orbital insertion phases of the delivery of a communications satellite to a geostationary orbit by means of a Delta launch vehicle. NASA plans to employ Delta vehicles for as long as they are needed during the transition period to the Space Shuttle. NASA planning for Atlas Centaur includes launches through 1985 for INTELSAT-VA, and through 1986 for FLTSATCOM satellites.

  9. GOES-R satellite solar panels ready for space

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-07-01

    An array of five photovoltaic panels has been approved and is ready to be incorporated into the National Oceanic and Atmospheric Administration's (NOAA) new Geostationary Operational Environmental Satellites-R (GOES-R). GOES-R, a collaborative effort between NOAA and NASA, aims to provide more timely and accurate weather forecasts once in orbit. The satellite is scheduled to launch in early 2016.

  10. Geosynchronous earth orbit/low earth orbit space object inspection and debris disposal: A preliminary analysis using a carrier satellite with deployable small satellites

    NASA Astrophysics Data System (ADS)

    Crockett, Derick

    Detailed observations of geosynchronous satellites from earth are very limited. To better inspect these high altitude satellites, the use of small, refuelable satellites is proposed. The small satellites are stationed on a carrier platform in an orbit near the population of geosynchronous satellites. A carrier platform equipped with deployable, refuelable SmallSats is a viable option to inspect geosynchronous satellites. The propellant requirement to transfer to a targeted geosynchronous satellite, perform a proximity inspection mission, and transfer back to the carrier platform in a nearby orbit is determined. Convex optimization and traditional optimization techniques are explored, determining minimum propellant trajectories. Propellant is measured by the total required change in velocity, delta-v. The trajectories were modeled in a relative reference frame using the Clohessy-Wiltshire equations. Mass estimations for the carrier platform and the SmallSat were determined by using the rocket equation. The mass estimates were compared to the mass of a single, non-refuelable satellite performing the same geosynchronous satellite inspection missions. From the minimum delta-v trajectories and the mass analysis, it is determined that using refuelable SmallSats and a carrier platform in a nearby orbit can be more efficient than using a single non-refuelable satellite to perform multiple geosynchronous satellite inspections.

  11. Satellite-tracking and earth-dynamics research programs. [NASA Programs on satellite orbits and satellite ground tracks of geodetic satellites

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Observations and research progress of the Smithsonian Astrophysical Observatory are reported. Satellite tracking networks (ground stations) are discussed and equipment (Baker-Nunn cameras) used to observe the satellites is described. The improvement of the accuracy of a laser ranging system of the ground stations is discussed. Also, research efforts in satellite geodesy (tides, gravity anomalies, plate tectonics) is discussed. The use of data processing for geophysical data is examined, and a data base for the Earth and Ocean Physics Applications Program is proposed. Analytical models of the earth's motion (computerized simulation) are described and the computation (numerical integration and algorithms) of satellite orbits affected by the earth's albedo, using computer techniques, is also considered. Research efforts in the study of the atmosphere are examined (the effect of drag on satellite motion), and models of the atmosphere based on satellite data are described.

  12. 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.

  13. Estimating Urban Temperature Bias Using Polar-Orbiting Satellite Data.

    NASA Astrophysics Data System (ADS)

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

    1994-03-01

    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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Geostationary Imaging FTS (GIFTS) Data Processing: Measurement Simulation and Compression

    NASA Technical Reports Server (NTRS)

    Huang, Hung-Lung; Revercomb, H. E.; Thom, J.; Antonelli, P. B.; Osborne, B.; Tobin, D.; Knuteson, R.; Garcia, R.; Dutcher, S.; Li, J.

    2001-01-01

    GIFTS (Geostationary Imaging Fourier Transform Spectrometer), a forerunner of next generation geostationary satellite weather observing systems, will be built to fly on the NASA EO-3 geostationary orbit mission in 2004 to demonstrate the use of large area detector arrays and readouts. Timely high spatial resolution images and quantitative soundings of clouds, water vapor, temperature, and pollutants of the atmosphere for weather prediction and air quality monitoring will be achieved. GIFTS is novel in terms of providing many scientific returns that traditionally can only be achieved by separate advanced imaging and sounding systems. GIFTS' ability to obtain half-hourly high vertical density wind over the full earth disk is revolutionary. However, these new technologies bring forth many challenges for data transmission, archiving, and geophysical data processing. In this paper, we will focus on the aspect of data volume and downlink issues by conducting a GIFTS data compression experiment. We will discuss the scenario of using principal component analysis as a foundation for atmospheric data retrieval and compression of uncalibrated and un-normalized interferograms. The effects of compression on the degradation of the signal and noise reduction in interferogram and spectral domains will be highlighted. A simulation system developed to model the GIFTS instrument measurements is described in detail.

  19. 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

  20. 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 evidence that stuff was going every-which-way at the beginning of the Galaxy, and Complex H is probably left over from that chaotic period." The new observations place Complex H at approximately 108,000 light-years from the Galactic center, and indicate that it is nearly 33,000 light-years across, containing approximately 6 million solar masses of hydrogen. Radio telescopes, like the GBT, are able to observe these cold, dark clouds of hydrogen because of the natural electromagnetic radiation emitted by neutral atomic hydrogen at radio wavelengths (21 centimeters). Globular clusters, and certain other objects in the extended Galactic halo, can be studied with optical telescopes because the material in them has collapsed to form hot, bright stars. The GBT is the world's largest fully steerable radio telescope. It was commissioned in August of 2000, and continues to be outfitted with the sensitive receivers and components that will allow it to make observations at much higher frequencies. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  1. 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.

  2. NAVSPASUR orbital processing for satellite break-up events

    NASA Technical Reports Server (NTRS)

    Schumacher, Paul W., Jr.

    1991-01-01

    Satellite breakups via explosion or collision can instantly increase the trackable orbiting population by up to several hundred objects, temporarily perturbing the routine space surveillance operations at U.S. Space Command (USSPACWCOM) and the Naval Space Surveillance Center (NAVSPASUR). This paper is a survey of some of the procedures and techniques used by NAVSPASUR to respond to such events. First, the overall data flow at NAVSPASUR is described highlighting the places at which human analysts may intervene with special processing. So-called manual intervention is required in a variety of non-nominal situations, including breakups. Second, a description is given of some of the orbital analysis and other software tools available to NAVSPASUR analysts. These tools were developed in-house over the past thirty years and can be employed in a highly flexible manner. The basic design philosophy for these tools was to implement simple concepts as efficiently as possible and to allow the analyst maximum use of his personal expertise. Finally, several historical breakup scenarios are discussed briefly. These scenarios provide examples of the types of questions that are fairly easy to answer in the present operational environment, as well as examples of questions that are very difficult to answer.

  3. Disposal strategy for the geosynchronous orbits of the Beidou Navigation Satellite System

    NASA Astrophysics Data System (ADS)

    Tang, Jingshi; Liu, Lin

    Beidou Navigation Satellite System (BDS) is China's navigation satelite system. It is now operational for navigation service in China and Asia-Pacific region and is due to be fully operational as a global navigation system by 2020. Unlike other navigation satellite systems, BDS consists of both 12-hour medium Earth orbit and 24-hour geosynchronous orbit. To sustain a safe environment for the navigation satellites, the end-of-life satellites must be disposed appropriately so they do not pose potential dangers to the operational satellites. There are currently two strategies for the disposal orbit. One is to put the disposed satellite in a graveyard orbit that has a safe distance from the operational satellites. It is often applied in geosynchronous orbits and such graveyard orbit can always maintain a safe distance even for a few centuries. This strategy is also currently adopted by GPS, yet recent researches show a re-entry orbit can sometimes be a better alternative. The interaction of Earth oblateness and lunisolar gravitation can lead to a rapid increase in the orbit eccentricity such that by proper design the disposed GPS satellite can be cleared out by re-entry into the atmosphere. In this work we focus on the disposal strategy for BDS geosynchronous orbit, which consists of the equatorial stationary orbit (GEO) and the inclined orbit (IGSO). We show that these two orbits are essentially in two different dynamical environments and evolve quite distinctly over a long period of time. Taking advantage of the dynamic nature, we apply the graveyard orbit and the re-entry orbit to GEO and IGSO respectively and propose appropriate disposal strategies accordingly.

  4. Scripting Module for the Satellite Orbit Analysis Program (SOAP)

    NASA Technical Reports Server (NTRS)

    Carnright, Robert; Paget, Jim; Coggi, John; Stodden, David

    2008-01-01

    This add-on module to the SOAP software can perform changes to simulation objects based on the occurrence of specific conditions. This allows the software to encompass simulation response of scheduled or physical events. Users can manipulate objects in the simulation environment under programmatic control. Inputs to the scripting module are Actions, Conditions, and the Script. Actions are arbitrary modifications to constructs such as Platform Objects (i.e. satellites), Sensor Objects (representing instruments or communication links), or Analysis Objects (user-defined logical or numeric variables). Examples of actions include changes to a satellite orbit ( v), changing a sensor-pointing direction, and the manipulation of a numerical expression. Conditions represent the circumstances under which Actions are performed and can be couched in If-Then-Else logic, like performing v at specific times or adding to the spacecraft power only when it is being illuminated by the Sun. The SOAP script represents the entire set of conditions being considered over a specific time interval. The output of the scripting module is a series of events, which are changes to objects at specific times. As the SOAP simulation clock runs forward, the scheduled events are performed. If the user sets the clock back in time, the events within that interval are automatically undone. This script offers an interface for defining scripts where the user does not have to remember the vocabulary of various keywords. Actions can be captured by employing the same user interface that is used to define the objects themselves. Conditions can be set to invoke Actions by selecting them from pull-down lists. Users define the script by selecting from the pool of defined conditions. Many space systems have to react to arbitrary events that can occur from scheduling or from the environment. For example, an instrument may cease to draw power when the area that it is tasked to observe is not in view. The contingency of the planetary body blocking the line of sight is a condition upon which the power being drawn is set to zero. It remains at zero until the observation objective is again in view. Computing the total power drawn by the instrument over a period of days or weeks can now take such factors into consideration. What makes the architecture especially powerful is that the scripting module can look ahead and behind in simulation time, and this temporal versatility can be leveraged in displays such as x-y plots. For example, a plot of a satellite s altitude as a function of time can take changes to the orbit into account.

  5. Comparison of high-level clouds represented in a global cloud system-resolving model with CALIPSO/CloudSat and geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Inoue, Toshiro; Satoh, Masaki; Hagihara, Yuichiro; Miura, Hiroaki; Schmetz, Johannes

    2010-01-01

    Vertical and horizontal distributions of high-level clouds (ice and snow) simulated in high-resolution global cloud system-resolving simulations by the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) are compared with satellite observations. Ice and snow data in a 1