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1

Geostationary Earth Orbit Satellite Model  

NSDL National Science Digital Library

The Geostationary Earth Orbit Satellite Model is a simple angular velocity model that uses Java3D for a realistic visualization of satellites in geostationary orbits. Students can view and explore the behavior of geostationary orbits, non-geostationary orbits, and non-physical orbits. This model tests the Java 3D implementation of the EJS 3D library. A warning message will appear if the Java 3D library is not available. The Geostationary Earth Orbit Satellite Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Wee, Loo K.

2012-04-08

2

Spectrum\\/Orbit Utilization Program for Geostationary Satellites  

Microsoft Academic Search

Mutual interferences among geostationary satellite communication systems determine the permitted spacing between satellites and the limits on the capacity of the orbit\\/spectrum resources available. This paper describes the \\

Edward F. Miller

1984-01-01

3

Spectrum\\/orbit utilization program for geostationary satellites  

Microsoft Academic Search

Mutual interferences among geostationary satellite communication systems determine the permitted spacing between satellites and the limits on the capacity of the orbit\\/spectrum resources available. This paper describes the computer program for analyzing the mutual interferences among communication satellite systems. Capabilities of the program are described. Inputs, models used, program operations, and program outputs are given. To show application of the

E. F. Miller

1984-01-01

4

Methods of rapid orbit forecasting after maneuvers for geostationary satellites  

Microsoft Academic Search

A geostationary (GEO) satellite may serve as a navigation satellite, but there is a problem that maneuvers frequently occur\\u000a and the forces are difficult to model. Based on the technique of determining satellite orbits by transfer, a predicted orbit\\u000a with high accuracy may be achieved by the method of statistical orbit determination in case of no maneuver force. The predicted

Xuhai Yang; Zhigang Li; Chugang Feng; Ji Guo; Huli Shi; Guoxiang Ai; Fenglei Wu; Rongchuan Qiao

2009-01-01

5

On orbital allotments for geostationary satellites  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

6

Servicing communication satellites in geostationary orbit  

NASA Technical Reports Server (NTRS)

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.

Russell, Paul K.; Price, Kent M.

1990-01-01

7

Astrometric positioning and orbit determination of geostationary satellites  

NASA Astrophysics Data System (ADS)

In the project titled “Astrometric Positioning of Geostationary Satellite” (PASAGE), carried out by the Real Instituto y Observatorio de la Armada (ROA), optical observation techniques were developed to allow satellites to be located in the geostationary ring with angular accuracies of up to a few tenths of an arcsec. These techniques do not necessarily require the use of large telescopes or especially dark areas, and furthermore, because optical observation is a passive method, they could be directly applicable to the detection and monitoring of passive objects such as space debris in the geostationary ring.By using single-station angular observations, geostationary satellite orbits with positional uncertainties below 350 m (2 sigma) were reconstructed using the Orbit Determination Tool Kit software, by Analytical Graphics, Inc. This software is used in collaboration with the Spanish Instituto Nacional de Técnica Aeroespacial.Orbit determination can be improved by taking into consideration the data from other stations, such as angular observations alone or together with ranging measurements to the satellite. Tests were carried out combining angular observations with the ranging measurements obtained from the Two-Way Satellite Time and Frequency Transfer technique that is used by ROA’s Time Section to carry out time transfer with other laboratories. Results show a reduction of the 2 sigma uncertainty to less than 100 m.

Montojo, F. J.; López Moratalla, T.; Abad, C.

2011-03-01

8

A geostationary Earth orbit satellite model using Easy Java Simulation  

NASA Astrophysics Data System (ADS)

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 3D view and associated learning in the real world; (2) comparative visualization of permanent geostationary satellites; (3) examples of non-geostationary orbits of different rotation senses, periods and planes; and (4) an incorrect physics model for conceptual discourse. General feedback from the students has been relatively positive, and we hope teachers will find the computer model useful in their own classes.

Wee, Loo Kang; Hwee Goh, Giam

2013-01-01

9

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

10

A Geostationary Earth Orbit Satellite Model Using Easy Java Simulation  

ERIC Educational Resources Information Center

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…

Wee, Loo Kang; Goh, Giam Hwee

2013-01-01

11

Factors Influencing the Choice of an Orbital Propulsion System for Geostationary Satellites.  

National Technical Information Service (NTIS)

The requirements of orbit control of geostationary communications satellites were investigated, and electrical propulsion for mission lives up to 15 years was compared. The mass of electrical propulsion is lower than that of chemical systems, even when ma...

G. Boersma F. J. Sonnenschein

1975-01-01

12

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

NASA Astrophysics Data System (ADS)

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.

Ma, Lihua

2011-01-01

13

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

14

Time Resolved Atmospheric Carbon Satellite Observations from Geostationary Orbit  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

15

47 CFR 25.146 - Licensing and operating authorization provisions for the non-geostationary satellite orbit fixed...  

Code of Federal Regulations, 2010 CFR

...authorization provisions for the non-geostationary satellite orbit fixed-satellite service (NGSO FSS) in the bands 10.7 GHz to...COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...

2010-10-01

16

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

Code of Federal Regulations, 2013 CFR

... Procedures for avoidance of in-line interference events for Non Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed-Satellite Service (FSS) Bands. 25.261 Section 25.261 Telecommunication...

2013-10-01

17

47 CFR 25.146 - Licensing and operating authorization provisions for the non-geostationary satellite orbit fixed...  

Code of Federal Regulations, 2010 CFR

...authorization provisions for the non-geostationary satellite orbit fixed-satellite service (NGSO FSS) in the bands 10.7 GHz to...COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...

2009-10-01

18

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

Code of Federal Regulations, 2010 CFR

...false Procedures for avoidance of in-line interference events for Non Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed Satellite Service (FSS) Bands. 25.261 Section 25.261 Telecommunication...

2009-10-01

19

Equitable aspects of access to and use of the geostationary satellite orbit  

NASA Astrophysics Data System (ADS)

The geostationary satellite orbit (GSO) and the radio frequency spectrum used by satellites in that orbit are mislabelled as "limited natural resources" by the international community. These physical phenomena are being expanded for use, they exist in perpetuity, they are inexhaustible, and they are not subject to sovereign claims or exclusive use by any nation. The geostationary satellite orbit's use must be a matter of pragmatic and reciprocal international cooperation and accommodation. In this situation, the GSO planning activities in the International Telecommunication Union must take into account not only the desires of nations to obtain access to the orbit, but also the equitability of claims made for use of the orbit. Treating the radio frequency spectrum and the GSO as a closed set of "limited natural resources" is not likely to produce the most efficient or effective results of any planning process. This paper explores equitable aspects of access to and the future use of the GSO.

Doyle, Stephen E.

20

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

21

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

22

Surface Solar Radiation Climate Data Sets derived from Geostationary and Polar-orbiting Satellites  

NASA Astrophysics Data System (ADS)

The incoming surface solar radiation has been defined as an essential climate variable by GCOS. It is useful to monitor one part of the earth's energy balance, and thus gain insights on the state and variability of the climate system. In addition, data sets of the surface solar radiation have received increased attention over the recent years as an important source of information for the planning of solar energy applications. The EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF) is deriving surface solar radiation from geostationary and polar-orbiting satellite instruments. While CM SAF is focusing on the generation of high-quality long-term climate data records, also operationally data is provided in short time latency. CM SAF now released both a data set based on geostationary Meteosat satellite covering 1983 to 2005 and a global data set based on measurements of the polar-orbiting AVHRR instruments covering 1982 to 2009. The geostationary observations allow the determination of the surface radiation at high spatial (0.03 x 0.03 deg) and temporal (hourly, daily, monthly) resolutions. Besides global radiation, also the direct beam component is provided, which is for instance required for the estimation of the energy generated by solar thermal plants. Using observations from polar-orbiting satellites allows to derive a global data set at a moderate spatial (0.25 x 0.25 deg) and temporal (daily, monthly) resolution. Based on comparisons with surface observations the accuracy of CM SAF surface solar radiation data is better than 10 W/m2 on a monthly basis and 25 W/m2 on a daily basis. Both data sets are well documented (incl. validation using surface observations) and available at no cost without restrictions at www.cmsaf.eu. We present a technical overview including validation results and application examples of the satellite-based surface solar radiation data generated and distributed by the CM SAF.

Trentmann, J.; Müller, R.; Träger-Chatterjee, C.; Posselt, R.; Stöckli, R.; Hollmann, R.

2012-12-01

23

Surface Solar Radiation climate data sets derived from Geostationary and Polar-orbiting Satellites  

NASA Astrophysics Data System (ADS)

The incoming surface solar radiation has been defined as an essential climate variable by GCOS. It is useful to monitor one part of the earth's energy balance, and thus gain insights on the state and variability of the climate system. In addition, data sets of the surface solar radiation have received increased attention over the recent years as an important source of information for the planning of solar energy applications. The EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF) is deriving surface solar radiation from geostationary and polar-orbiting satellite instruments. While CM SAF is focusing on the generation of high-quality long-term climate data records, also operationally data is provided in short time latency within 8 weeks. CM SAF now released both a data set based on geostationary Meteosat satellite covering 1983 to 2005 (doi: 10.5676/EUM_SAF_CM/RAD_MVIRI/V001) and a global data set based on measurements of the polar-orbiting AVHRR instruments covering 1982 to 2009 (doi: 10.5676/EUM_SAF_CM/CLARA_AVHRR/V001). The geostationary observations allow the determination of the surface radiation at high spatial (0.03 x 0.03 deg) and temporal (hourly, daily, monthly) resolutions. Besides global radiation, also the direct beam component is provided, which is for instance required for the estimation of the energy generated by solar thermal plants. Using observations from polar-orbiting satellites allows to derive a global data set at a moderate spatial (0.25 x 0.25 deg) and temporal (daily, monthly) resolution. Based on comparisons with surface observations the accuracy of CM SAF surface solar radiation data is better than 10 W/m2 on a monthly basis and 25 W/m2 on a daily basis. Both data sets are well documented (incl. validation using surface observations) and available at no cost without restrictions at www.cmsaf.eu. Here, we present a technical overview including validation results and application examples of the satellite-based surface solar radiation data generated and distributed by the CM SAF.

Trentmann, Jörg; Müller, Richard W.; Posselt, Rebekka; Stöckli, Reto

2013-04-01

24

Surface Solar Radiation climate data sets derived from Geostationary and Polar-orbiting Satellites  

NASA Astrophysics Data System (ADS)

The incoming surface solar radiation has been defined as an essential climate variable by GCOS. It is useful to monitor as part of the earth's energy balance, and thus gain insights on the state and variability of the climate system. In addition, data sets of the surface solar radiation have received increased attention over the recent years as an important source of information for the planning of solar energy applications. The EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF, www.cmsaf.eu) is deriving surface solar radiation from geostationary and polar-orbiting satellite instruments. While CM SAF is focusing on the generation of high-quality long-term climate data records, also operationally data is provided in short time latency within 8 weeks. CM SAF has released two climate data records of the surface solar radiation: One based on geostationary Meteosat satellite covering 1983 to 2005 (doi:10.5676/EUM_SAF_CM/RAD_MVIRI/V001) and one global data set based on measurements of the polar-orbiting AVHRR instruments covering 1982 to 2009 (doi: 10.5676/EUM_SAF_CM/CLARA_AVHRR/V001). The geostationary observations allow the determination of the surface radiation at high spatial (0.03 x 0.03 deg) and temporal (hourly, daily, monthly) resolutions. Besides global radiation, also the direct beam component is provided, which is required for the estimation of the energy generated by solar thermal plants. Using observations from polar-orbiting satellites allows to derive a global data set at a moderate spatial (0.25 x 0.25 deg) and temporal (daily, monthly) resolution. Based on comparisons with surface observations the accuracy of CM SAF surface solar radiation data is better than 10 W/m2 on a monthly basis and 25 W/m2 on a daily basis. Both data sets are well documented (incl. validation using surface observations) and available at no cost without restrictions at www.cmsaf.eu. Here, we present an overview of the data sets including validation results and application examples of the satellite-based surface solar radiation data generated and distributed by the CM SAF.

Trentmann, Jörg; Müller, Richard; Posselt, Rebekka; Stöckli, Reto

2014-05-01

25

Geostationary orbit determination using SATRE  

NASA Astrophysics Data System (ADS)

A new strategy of precise orbit determination (POD) for GEO (Geostationary Earth Orbit) satellite using SATRE (SAtellite Time and Ranging Equipment) is presented. Two observation modes are proposed and different channels of the same instruments are used to construct different observation modes, one mode receiving time signals from their own station and the other mode receiving time signals from each other for two stations called pairs of combined observations. Using data from such a tracking network in China, the results for both modes are compared. The precise orbit determination for the Sino-1 satellite using the data from 6 June 2005 to 13 June 2005 has been carried out in this work. The RMS (Root-Mean-Square) of observing residuals for 3-day solutions with the former mode is better than 9.1 cm. The RMS of observing residuals for 3-day solutions with the latter mode is better than 4.8 cm, much better than the former mode. Orbital overlapping (3-day orbit solution with 1-day orbit overlap) tests show that the RMS of the orbit difference for the former mode is 0.16 m in the radial direction, 0.53 m in the along-track direction, 0.97 m in the cross-track direction and 1.12 m in the 3-dimension position and the RMS of the orbit difference for the latter mode is 0.36 m in the radial direction, 0.89 m in the along-track direction, 1.18 m in the cross-track direction and 1.52 m in the 3-dimension position, almost the same as the former mode. All the experiments indicate that a meter-level accuracy of orbit determination for geostationary satellite is achievable.

Lei, Hui; Li, ZhiGang; Yang, XuHai; Wu, WenJun; Cheng, Xuan; Yang, Ying; Feng, ChuGang

2011-09-01

26

Land Surface Temperature- Comparing Data from Polar Orbiting and Geostationary Satellites  

NASA Astrophysics Data System (ADS)

Land Surface Temperature (LST) is a vital parameter in Earth climate science, driving long-wave radiation exchanges that control the surface energy budget and carbon fluxes, which are important factors in Numerical Weather Prediction (NWP) and the monitoring of climate change. Satellites offer a convenient way to observe LST consistently and regularly over large areas. A comparison between LST retrieved from a Geostationary Instrument, the Spinning Enhanced Visible and InfraRed Imager (SEVIRI), and a Polar Orbiting Instrument, the Advanced Along Track Scanning Radiometer (AATSR) is presented. Both sensors offer differing benefits. AATSR offers superior precision and spatial resolution with global coverage but given its sun-synchronous platform only observes at two local times, ~10am and ~10pm. SEVIRI provides the high-temporal resolution (every 15 minutes) required for observing diurnal variability of surface temperatures but given its geostationary platform has a poorer resolution, 3km at nadir, which declines at higher latitudes. A number of retrieval methods are applied to the raw satellite data: First order coefficient based algorithms provided on an operational basis by the LandSAF (for SEVIRI) and the University of Leicester (for AATSR); Second order coefficient based algorithms put forward by the University of Valencia; and an optimal estimation method using the 1DVar software provided by the NWP SAF. Optimal estimation is an iterative technique based upon inverse theory, thus is very useful for expanding into data assimilation systems. The retrievals are assessed and compared on both a fine scale using in-situ data from recognised validation sites and on a broad scale using two 100x100 regions such that biases can be better understood. Overall, the importance of LST lies in monitoring daily temperature extremes, e.g. for estimating permafrost thawing depth or risk of crop damage due to frost, hence the ideal dataset would use a combination of observations. Results show that there is a strong agreement for night-time matchups and understandable biases for the daytime matchups, owing to the differing viewing geometry and relative sun position. This comparison gives promise to the possibility of constructing a combined retrieval mechanism which draws the best characteristics from each instrument with possible courses of action identified.

Comyn-Platt, E.; Remedios, J. J.; Good, E. J.; Ghent, D.; Saunders, R.

2012-04-01

27

Radio frequency interference at the geostationary orbit  

NASA Technical Reports Server (NTRS)

Growing demands on the frequency spectrum have increased the possibility of radio frequency interference (RFI). Various approaches to obtain in orbit RFI data are compared; this comparision indicates that the most practical way to obtain RFI data for a desired orbit (such as a geostationary orbit) is through the extrapolation of in orbit RFI measurements by a low orbit satellite. It is concluded that a coherent RFI program that uses both experimental data and analytical predictions provides accurate RFI data at minimal cost.

Sue, M. K.

1981-01-01

28

A user assessment of servicing at geostationary orbit  

NASA Technical Reports Server (NTRS)

Orbital servicing assessed from the viewpoint of a commercial user of communications satellites at geostationary orbit. The need for servicing is emphasized by looking at the history of failures and defects occurring in communications satellites. The methods used in servicing were evaluated in terms of the needs of a communications satellite user. A system that utilizes servicing was studied, and some benefits in addition to cost savings were identified. Most of the assumptions and conclusions apply to earth observation satellites at geostationary orbit.

Gordon, G. D.

1975-01-01

29

Servicing of geostationary satellites  

NASA Astrophysics Data System (ADS)

Operational features and capabilities of a prospective automated spacecraft servicer for GEO-positioned satellites are described. The servicer spacecraft would have remote manipulation capability and a rendezvous capability, a grappler, a servo-controlled arm, and real-time video cameras. Specific applications for telecommunication satellites are considered, noting that the service module would carry a store of spare component modules for insertion into defective spacecraft. The servicer would be in orbit while a spare parts container, filled with components for satellites with identified defects, is launched into an orbit on an Ariane 4. The container would carry a beacon for the servicer to home in on. The servicer is designed for a 5-7 year autonomous life, would consume 250 W, have a 10 kbit/sec telemetry link and two 6 Mbit/sec video links, a one meter antenna, and 20 W of RF power. Visits to 12 satellites are foreseen for the 1050 kg spacecraft.

Grosjean, O.; Pircher, M.; Prado, J.-Y.; Runavot, J.-J.

1982-09-01

30

The radiation environment of the geostationary orbit for magnetically quiet conditions according to data from the Raduga communication satellites  

Microsoft Academic Search

An analysis is made of data on integral proton fluxes at energies ranging from 270 keV to 5 MeV and of differential fluxes of low-energy (0.3-5 keV) electrons in geostationary orbit under magnetically quiet conditions characterized by a Kp index not greater than 1. The results make it possible to predict the radiation environment of the geostationary orbit under magnetically

Iu. I. Vakulin; O. S. Grafodatskii; V. I. Degtiarev; V. I. Dovgii; G. A. Zherebtsov

1988-01-01

31

Electric propulsion for geostationary orbit insertion  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

32

Transmitter diversity verification on ARTEMIS geostationary satellite  

NASA Astrophysics Data System (ADS)

Optical feeder links will become the extension of the terrestrial fiber communications towards space, increasing data throughput in satellite communications by overcoming the spectrum limitations of classical RF-links. The geostationary telecommunication satellite Alphasat and the satellites forming the EDRS-system will become the next generation for high-speed data-relay services. The ESA satellite ARTEMIS, precursor for geostationary orbit (GEO) optical terminals, is still a privileged experiment platform to characterize the turbulent channel and investigate the challenges of free-space optical communication to GEO. In this framework, two measurement campaigns were conducted with the scope of verifying the benefits of transmitter diversity in the uplink. To evaluate this mitigation technique, intensity measurements were carried out at both ends of the link. The scintillation parameter is calculated and compared to theory and, additionally, the Fried Parameter is estimated by using a focus camera to monitor the turbulence strength.

Mata Calvo, Ramon; Becker, Peter; Giggenbach, Dirk; Moll, Florian; Schwarzer, Malte; Hinz, Martin; Sodnik, Zoran

2014-03-01

33

Geostationary Satellite Server  

NSDL National Science Digital Library

This database contains imagery from geosationary satellites. Visitors can access daily images or archived imagery form GOES-9, METEOSAT, and other satellites. The imagery features hemispheric and whole-disk views of Earth, water vapor maps, and images of storms and other special events. Links to satellite homepages and to other related topics are included.

34

Crew Transfer Options for Servicing of Geostationary Satellites.  

National Technical Information Service (NTIS)

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 th...

J. A. Cerro

2012-01-01

35

Impact of non-geostationary orbits on PASS  

NASA Technical Reports Server (NTRS)

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.

Estabrook, Polly; Motamedi, Masoud

1990-01-01

36

The geostationary orbit and developing countries  

NASA Technical Reports Server (NTRS)

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.

Medina, E. R.

1982-01-01

37

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

Federal Register 2010, 2011, 2012, 2013

...CFR Parts 2 and 25 [IB Docket No. 12-376; FCC 12-161] Earth Stations Aboard Aircraft Communicating with Fixed-Satellite...Register of March 8, 2013. The document proposed rules for Earth Stations Aboard Aircraft. FOR FURTHER INFORMATION...

2013-03-29

38

Single-event and total-dose effects in geo-stationary transfer orbit during solar-activity maximum period measured by the Tsubasa satellite  

NASA Astrophysics Data System (ADS)

The Tsubasa satellite developed by the Japan Aerospace Exploration Agency was launched in Feb 2002 into Geo-stationary Transfer Orbit GTO Perigee 500km Apogee 36000km and had been operated well until Sep 2003 The objective of this satellite was to verify the function of commercial parts and new technologies of bus-system components in space Thus the on-board experiments were conducted in the more severe radiation environment of GTO rather than in Geo-stationary Earth Orbit GEO or Low Earth Orbit LEO The Space Environment Data Acquisition equipment SEDA on board the Tsubasa satellite had the Single-event Upset Monitor SUM and the DOSimeter DOS to evaluate influences on electronic devices caused by radiation environment that was also measured by the particle detectors of the SEDA the Standard DOse Monitor SDOM for measurements of light particles and the Heavy Ion Telescope HIT for measurements of heavy ions The SUM monitored single-event upsets and single-event latch-ups occurred in the test sample of two 64-Mbit DRAMs The DOS measured accumulated radiation dose at fifty-six locations in the body of the Tsubasa satellite Using the data obtained by these instruments single-event and total-dose effects in GTO during solar-activity maximum period especially their rapid changes due to solar flares and CMEs in the region from L 1 1 through L 11 is discussed in this paper

Koshiishi, H.; Kimoto, Y.; Matsumoto, H.; Goka, T.

39

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2013 CFR

...false Interference to geostationary-satellites. 78.106 Section 78.106 Telecommunication...106 Interference to geostationary-satellites. Applicants and licensees must...potential of interference to geostationary-satellites. [68 FR 12776, Mar. 17,...

2013-10-01

40

47 CFR 101.145 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2013 CFR

...false Interference to geostationary-satellites. 101.145 Section 101.145 ...145 Interference to geostationary-satellites. These limitations are necessary...geostationary-space stations in the fixed-satellite service. (a) Stations...

2013-10-01

41

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2013 CFR

...false Interference to geostationary-satellites. 74.643 Section 74.643 Telecommunication...643 Interference to geostationary-satellites. Applicants and licensees must...potential of interference to geostationary-satellites. [68 FR 12771, Mar. 17,...

2013-10-01

42

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

Microsoft Academic Search

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

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

2003-01-01

43

Earth radiation budget data from geostationary orbit  

Microsoft Academic Search

The Geostationary Earth Radiation Budget (GERB) instrument will be the first instrument dedicated to measure the Earth radiation budget (ERB) from geostationary orbit from the year 2000 onward. GERB combines both, spectral broadband measurements and high temporal resolution. The GERB spectral bandpass reaches from 0.32 ?m beyond 30 ?m. A quartz filter inserted at every second image limits the bandpass

J. Mueller; R. Stuhlmann; R. Rhollmann; K. Dammann; J. Harries; R. Mossavati; R. Wrigley; S. Kellock

1999-01-01

44

Japan's geostationary meteorological satellite system  

NASA Astrophysics Data System (ADS)

Equipment characteristics and missions of the Japanese geostationary meteorological satellites (GMS) are examined. GMS-1 was launched in July 1977 on a NASA Delta vehicle. GMS-2 launched from Japan, was placed into GEO in August 1981. Both spacecraft were designed for a weather watch using a visible/IR spin scan radiometer (VISSR) instrument, collection and distribution of weather data, and monitoring of solar particles. The GMS-1 unit operated on the UHF bands while the second was switched over to S-band. Solar arrays provided battery trickle-charge power with a lifetime of 5 yr. A final instrumentation component common to both spacecraft is a space environment monitor for investigating the effect of solar activity on earth communications systems.

Steggall, N.

1982-06-01

45

A statistical survey of ELF waves in a geostationary orbit  

SciTech Connect

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.

Parrot, M.; Gaye, C.A. [Laboratoire de Physique et Chimie de l`Environment, Orleans (France)] [Laboratoire de Physique et Chimie de l`Environment, Orleans (France)

1994-11-15

46

Weather Satellite and Orbits  

NSDL National Science Digital Library

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

47

Development of the European Small Geostationary Satellite SGEO  

NASA Astrophysics Data System (ADS)

The SGEO product portfolio, ranging from Satellite platform delivery up to in-orbit delivery of a turnkey system including satellite and ground control station, is designed for applications ranging from TV Broadcast to multimedia applications, Internet access, mobile or fixed services in a wide range of frequency bands. Furthermore, Data Relay missions such as the European Data Relay Satellite (EDRS) as well as other institutional missions are targeted. Key design features of the SGEO platform are high flexibility and modularity in order to accommodate a very wide range of future missions, a short development time below two years and the objective to build the system based on ITAR free subsystems and components. The system will provide a long lifetime of up to 15 years in orbit operations with high reliability. SGEO is the first European satellite to perform all orbit control tasks solely by electrical propulsion (EP). This design provides high mass efficiency and the capability for direct injection into geostationary orbit without chemical propulsion (CP). Optionally, an Apogee Engine Module based on CP will provide the perigee raising manoeuvres in case of a launch into geostationary transfer orbit (GTO). This approach allows an ideal choice out of a wide range of launcher candidates in dependence of the required payload capacity. SGEO will offer to the market a versatile and high performance satellite system with low investment risk for the customer and a short development time. This paper provides an overview of the SGEO system key features and the current status of the SGEO programme.

Lübberstedt, H.; Schneider, A.; Schuff, H.; Miesner, Th.; Winkler, A.

2008-08-01

48

A geographical location based satellite selection scheme for a novel constellation composed of quasi-geostationary satellites  

Microsoft Academic Search

In order to realize the dream of global broadband coverage, the need for satellite communication systems has grown rapidly during the last few years. Several low Earth orbit (LEO), medium Earth orbit (MEO), and geostationary (GEO) satellite constellations have been thus proposed in the recent literature. However, these constellations either require a potential number of satellites or are unable to

Tarik Taleb; Umith Dharmaratna; Nei Kato; Yoshiaki Nemoto

2005-01-01

49

Surface albedo based on geostationary satellite observations  

NASA Astrophysics Data System (ADS)

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 63°E and at JMA using 140°E geostationary data. To support development of an aggregate global albedo product, NCDC will apply the GSA algorithm to data from GOES-E (75°W) and GOES-W (135°W). 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.

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

2011-12-01

50

Geostationary satellites autonomous closed loop station keeping  

NASA Astrophysics Data System (ADS)

This paper deals with a novel approach to geostationary satellite station keeping based on the use of a closed loop control law without recourse to previously computed reference trajectories. The closed loop control implementation requires the knowledge of the spacecraft position and velocity with respect to Earth in real time. Numerical results are presented to illustrate this technique. Simulation results showing the feasibility of station keeping on a spacecraft equipped with electric thrusters are also presented.

Guelman, Mauricio M.

2014-04-01

51

Evaluation of geostationary and polar orbiting satellites to collect meteorological data from automatic stations in the Antarctic Peninsula  

NASA Astrophysics Data System (ADS)

This paper summarizes the main results, needs and perspectives on the use of Satellite Data Collection Systems (DCS) in the Antarctic Peninsula as derived from the operation of an experimental net of five Data Collection Platforms (DCPs) installed to collect meteorological data from remote sites, during the period 1978-1984. Main logistics problems have been solved and also the maintenance of a continuous data link along the year through Landsat (initially) and GOES satellites (actually). It is hoped to solve in the near future the remaining data quality problems on the DCP sensors.

Araya, Mauricio F.

52

Relative orbit control of collocated geostationary spacecraft  

NASA Astrophysics Data System (ADS)

A relative orbit control concept for collocated geostationary spacecraft is presented. One chief spacecraft, controlled from the ground, is responsible for the orbit determination and control of the remaining vehicles. Any orbit relative to the chief is described in terms of equinoctial orbit element differences and a linear mapping is employed for quick transformation from relative orbit measurements to orbit element differences. It is demonstrated that the concept is well-suited for spacecraft that are collocated using eccentricity-inclination vector separation and this formulation still allows for the continued use of well established and currently employed stationkeeping schemes, such as the Sun-pointing-perigee strategy. The relative approach allows to take determinisitc thruster cross-coupling effects in the computation of stationkeeping corrections into account. The control cost for the proposed concept is comparable to ground-based stationkeeping. A relative line-of-sight constraint between spacecraft separated in longitude is also considered and an algorithm is developed to provide enforcement options. The proposed on-board control approach maintains the deputy spacecraft relative orbit, is competitive in terms of propellant consumption, allows enforcement of a relative line-of-sight constraint and offers increased autonomy and flexibility for future missions.

Rausch, Raoul R.

53

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

Code of Federal Regulations, 2013 CFR

...for non-geostationary and geostationary satellite systems in frequencies allocated to the fixed-satellite service. 25.278 Section 25.278...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations...

2013-10-01

54

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)

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.

Barrios, José Miguel; Ghilain, Nicolas; Arboleda, Alirio; Gellens-Meulenberghs, Françoise

2014-05-01

55

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

56

Future Remote sensing from the Geostationary Earth Orbit  

NASA Astrophysics Data System (ADS)

The ability of satellite based instrumentation to monitor large regions of the Earth at regular intervals is a key part of remote sensing from space and is inherently linked to the orbit of the host spacecraft. For remote sensing, the vast majority of missions have so far utilised the low Earth orbit (LEO), usually in a sun-synchronous polar orbit. Deficiencies of LEO with respect to remote sensing include poor temporal sampling over low-to-mid latitudes and the inability to monitor Earth system processes that have a rate of change of minutes to hours. Examples of such processes include atmospheric chemistry, clouds, water vapour, fires and cyclonic weather systems. Potentially, use of space-based instruments in geostationary Earth orbit (GEO) can overcome the problem of temporal under-sampling. To date, the use of GEO for remote sensing has been restricted in the main to meteorological satellites such as METEOSAT and GOES. The advantage of GEO based observation does not lie solely in the increased revisit time but also in that GEO offers improved sampling, in the VIS-IR, through an increased likelihood of capturing cloud free scenes. Uniquely, the viewing geometry of the GEO offers a fixed viewing and a variable illumination angle that may offer improved data for land surface applications by removing shadowing effects. The GEO does have its disadvantages however, including limited latitudinal and longitudinal total coverage. In addition, the large distance from the Earth to the GEO satellite coupled to the zenith dependence of sun angle can under some circumstances present radiometric limits. The purpose of this talk is to introduce the many areas of Earth system science that will benefit from Geostationary remote sensing, covering the biosphere, the hydrosphere and the atmosphere.

Corlett, G.; Monks, P.

57

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

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

58

Radar for Monitoring Hurricanes from Geostationary Orbit  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

59

Estimating Solar Irradiance using a Geostationary Satellite  

NASA Astrophysics Data System (ADS)

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.

Urquhart, Bryan Glenn

60

Surface solar radiation from geostationary satellites for renewable energy  

Microsoft Academic Search

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

Istvan Laszlo; Hongqing Liu; Andrew Heidinger; Mitchell Goldberg

2010-01-01

61

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)

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.

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

2012-12-01

62

Geostationary payload concepts for personal satellite communications  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

63

Geostationary payload concepts for personal satellite communications  

NASA Astrophysics Data System (ADS)

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.

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

64

Ozone air quality measurement requirements for a geostationary satellite mission  

NASA Astrophysics Data System (ADS)

We conduct an Observing System Simulation Experiment (OSSE) to test the ability of geostationary satellite measurements of ozone in different spectral regions to constrain surface ozone concentrations through data assimilation. Our purpose is to define instrument requirements for the NASA GEO-CAPE geostationary air quality mission over North America. We consider instruments using different spectral combinations of UV (290-340 nm), Vis (560-620 nm), and thermal IR (TIR, 9.6 ?m). Hourly ozone data from the MOZART global 3-D chemical transport model (CTM) are taken as the "true" atmosphere to be sampled by the instruments for July 2001. The resulting synthetic data are assimilated in the GEOS-Chem CTM using a Kalman filter. The MOZART and GEOS-Chem CTMs have independent heritages and use different assimilated meteorological data sets for the same period, making for an objective OSSE. We show that hourly observations of ozone from geostationary orbit improve the assimilation considerably relative to daily observation from low earth orbit, and that broad observation over the ocean is unnecessary if the objective is to constrain surface ozone distribution over land. We also show that there is little propagation of ozone information from the free troposphere to the surface, so that instrument sensitivity in the boundary layer is essential. UV + Vis and UV + TIR spectral combinations improve greatly the information on surface ozone relative to UV alone. UV + TIR is preferable under high-sensitivity conditions with strong thermal contrast at the surface, but UV + Vis is preferable under low-sensitivity conditions. Assimilation of data from a UV + Vis + TIR instrument reduces the GEOS-Chem error for surface ozone by a factor of two. Observation in the TIR is critical to obtain ozone information in the upper troposphere relevant to climate forcing.

Zoogman, Peter; Jacob, Daniel J.; Chance, Kelly; Zhang, Lin; Le Sager, Philippe; Fiore, Arlene M.; Eldering, Annmarie; Liu, Xiong; Natraj, Vijay; Kulawik, Susan S.

2011-12-01

65

High Temporal and Spatial Resolution Coverage of Earth from Commercial AVSTAR Systems in Geostationary Orbit  

Microsoft Academic Search

Imaging the earth from Geostationary Earth Orbit (GEO) allows frequent updates of environmental conditions within an observable hemisphere at time and spatial scales appropriate to the most transient observable terrestrial phenomena. Coverage provided by current GEO Meteorological Satellites (METSATS) fails to fully exploit this advantage due primarily to obsolescent technology and also institutional inertia. With the full benefit of GEO

M. A. Lecompte; J. F. Heaps; F. H. Williams

2002-01-01

66

Tropical Cyclone Precipitation Estimation Technique Using Geostationary Satellite Data.  

National Technical Information Service (NTIS)

This memorandum presents a technique for estimating precipitation from tropical cyclones using visible and infrared geostationary satellite data. The technique assigns rainfall rates to tropical cyclone cloud features, yields a rainfall potential of the c...

L. E. Spayd R. A. Scofield

1984-01-01

67

Analysis of Galileo Style Geostationary Satellite Imaging: Image Reconstruction.  

National Technical Information Service (NTIS)

Earlier this year DARPA announced the Galileo project, with the basic conceptual idea of using optical interferometry to combine the light from two telescopes, with one of them being movable, to image geostationary satellites. This project aims at obtaini...

A. M. Jorgensen D. Mozurkewich H. R. Schmitt J. T. Armstrong S. R. Restaino

2012-01-01

68

Geostationary orbit Earth science platform concepts for global change monitoring  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

69

The development of a Russian communication satellite of small class, operating in the geostationary and high-elliptical orbits 1 1 Paper IAF 96-11.2.08 presented at the 47th International Astronautical Congress, Beijing, China, 7–11 October 1996  

Microsoft Academic Search

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

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

1997-01-01

70

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

NASA Astrophysics Data System (ADS)

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.

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

71

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

72

Crew Transfer Options for Servicing of Geostationary Satellites  

NASA Technical Reports Server (NTRS)

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.

Cerro, Jeffrey A.

2012-01-01

73

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

74

Analysis and Design of the Automatic Flight Dynamics Operations For Geostationary Satellite Mission  

NASA Astrophysics Data System (ADS)

Automation of the key flight dynamics operations for the geostationary orbit satellite mission is analyzed and designed. The automation includes satellite orbit determination, orbit prediction, event prediction, and fuel accounting. An object-oriented analysis and design methodology is used for design of the automation system. Automation scenarios are investigated first and then the scenarios are allocated to use cases. Sequences of the use cases are diagramed. Then software components and graphical user interfaces are designed for automation. The automation will be applied to the Communication, Ocean, and Meteorology Satellite (COMS) flight dynamics system for daily routine operations.

Lee, Byoung-Sun; Hwang, Yoola; Park, Sangwook; Lee, Young-Ran; Santiago Noguero Galilea, Javier

2009-06-01

75

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

76

Solar irradiance estimation from geostationary satellite data: 1. Statistical models  

Microsoft Academic Search

The use of satellite data to estimate solar irradiance at ground level represents a valid alternative to ground measurements of solar radiation. The best known methods of estimating the solar irradiance at the earth's surface using geostationary satellite data are reviewed. The models may be classified into statistical and physical models, depending on the approach used to treat the interaction

M. Noia; C. F. Ratto; R. Festa

1993-01-01

77

Local orbital debris flux study in the geostationary ring  

NASA Astrophysics Data System (ADS)

A local orbital debris flux analysis is performed in the geostationary (GEO) ring to investigate how frequently near-miss events occur for each longitude slot in the GEO ring. The current resident space object (RSO) environment at GEO is evaluated, and publicly-available two-line element (TLE) data are utilized in tandem with a geostationary torus configuration to simulate near-miss events incurred by the trackable RSO population at GEO. Methodology for determining near-miss events with this formulation is introduced, and the results of the analysis for a one-year time frame are provided to illustrate the need for active GEO remediation.

Anderson, Paul V.; Schaub, Hanspeter

2013-06-01

78

Cloud Property Retrievals from Geostationary Satellites for Aviation Weather Applications  

NASA Astrophysics Data System (ADS)

A near-real time analysis system has been developed to retrieve cloud and radiation properties from operational geostationary satellite imager data. It is currently being applied to GOES-11/12, Meteosat-9, and MTSAT-1R, as well as to polar orbiting satellite imagers. The North American domain, which includes much of Canada, the USA, and Mexico, is analyzed each half hour using data from GOES-11 and 12. Selected cloud properties including cloud phase, effective particle size, top and base heights, optical depth, and ice/liquid water path are made available digitally for use in an aircraft icing potential product and in numerical weather prediction model assimilation. In addition to their use in the Current Icing Potential Product, the analysis system generates a nowcasting aircraft icing index and estimate of ceiling heights. Recent advances to these analyses include improved nighttime retrievals and daytime multilayer cloud retrievals. The latter has significantly increased the amount of usable data for detection of icing conditions. These products and many others are also made available online in digital and image formats for use by other researchers, forecasters and the public. This paper will present examples of the results and validation efforts to date.

Minnis, P.; Palikonda, R.; Smith, W. L.; Chee, T.; Spangenberg, D. A.; Ayers, J. K.; Chang, F.-L.; Heck, P. W.

2009-09-01

79

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

80

Performance Analysis of the HTTP Protocol on Geostationary Satellite Links  

NASA Technical Reports Server (NTRS)

Various issues associated with HTTP protocol on geostationary satellite links are presented in viewgraph form. Specific topics include: 1) Network reference points; 2) The HTTP 1.0 and 1.1 mechanisms; 3) Experimental setup; 4) TCP and HTTP configuration; 5) Modelling slow start and 6) Results and future work.

Krus, Hans; Allman, Mark; Griner, Jim; Tran, Diepchi

1998-01-01

81

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

Microsoft Academic Search

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,

G. Rajaram

2006-01-01

82

Ka-band geostationary satellite spacing requirements and access schemes  

NASA Technical Reports Server (NTRS)

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.

Caron, Mario; Hindson, Daniel J.

1995-01-01

83

Air Quality Science and Regulatory Efforts Require Geostationary Satellite Measurements  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

84

Displaced geostationary orbits using hybrid low-thrust propulsion  

NASA Astrophysics Data System (ADS)

In this paper, displaced geostationary orbits using hybrid low-thrust propulsion, a complementary combination of Solar Electric Propulsion (SEP) and solar sailing, are investigated to increase the capacity of the geostationary ring that is starting to become congested. The SEP propellant consumption is minimized in order to maximize the mission lifetime by deriving semi-analytical formulae for the optimal steering laws for the SEP and solar sail accelerations. By considering the spacecraft mass budget, the performance is also expressed in terms of payload mass capacity. The analyses are performed both for the use of pure SEP and hybrid low-thrust propulsion to allow for a comparison. It is found that hybrid low-thrust control outperforms the pure SEP case both in terms of payload mass capacity and mission lifetime for all displacements considered. Hybrid low-thrust propulsion enables payloads of 255-487 kg to be maintained in a 35 km displaced orbit for 10-15 years. Adding the influence of the J2 and J terms of the Earth's gravity field has a small effect on this lifetime, which becomes almost negligible for small values of the sail lightness number. Finally, two SEP transfers that allow for an improvement in the performance of hybrid low-thrust control are optimized for the propellant consumption by solving the accompanying optimal control problem using a direct pseudospectral method. The first type of transfer enables a transit between orbits displaced above and below the equatorial plane, while the second type of transfer enables customized service for which a spacecraft is transferred to a Keplerian parking orbit when geostationary coverage is not needed. While the latter requires a modest propellant budget, the first type of transfer comes at the cost of an almost negligible SEP propellant consumption.

Heiligers, Jeannette; McInnes, Colin R.; Biggs, James D.; Ceriotti, Matteo

2012-02-01

85

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

NASA Technical Reports Server (NTRS)

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.

Brousse, Pascal; Desprairies, Arnaud

1993-01-01

86

Apple - Indian experimental geostationary communication satellite  

Microsoft Academic Search

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

U. R. Rao; R. M. Vasagam

1982-01-01

87

Operational Experience of the Use of a Generic Product for Collision Risk Assessment on Geostationary orbit  

Microsoft Academic Search

The risk of collision of a geostationary satellite with uncontrolled debris or other satellites is currently estimated to be above 1% over the 13 years of a mission lifetime and has increased an order of magnitude in the last decade. Many geostationary satellite operators have started to control this risk in the last few years. GMV, a recognised leader in

L. Martin; J. Baker; F. Martinez; G. Garcia

2004-01-01

88

Satellite orbit predictor  

NASA Technical Reports Server (NTRS)

An analog aid to determine satellite coverage of Emergency Locator Transmitters Emergency Position Indicating Radio Beacon (ELT/EPIRB) distress incidence is discussed. The satellite orbit predictor is a graphical aid for determining the relationship between the satellite orbit, antenna coverage of the spacecraft and coverage of the Local User Terminal. 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.A table of equator crossings for each satellite is included.

Friedman, Morton l.; Garrett, James, Major

89

Future Remote sensing from the Geostationary Earth Orbit  

Microsoft Academic Search

The ability of satellite based instrumentation to monitor large regions of the Earth at regular intervals is a key part of remote sensing from space and is inherently linked to the orbit of the host spacecraft. For remote sensing, the vast majority of missions have so far utilised the low Earth orbit (LEO), usually in a sun-synchronous polar orbit. Deficiencies

G. Corlett; P. Monks

2002-01-01

90

Fuzzy logic techniques for rendezvous and docking of two geostationary satellites  

NASA Technical Reports Server (NTRS)

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.

Ortega, Guillermo

1995-01-01

91

Satellites Orbiting Earth  

NSDL National Science Digital Library

In recent years, there has been a push to better understand how Earth works as a system- how land, oceans, air, and life all interact. Satellites in orbit around Earth are a fast and efficient way of gathering remotely sensed data about the planet as a whole. This animated video shows the orbital paths of the satellites in the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS), a collection of satellites that work together to study Earth on a wide scale.

92

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

Code of Federal Regulations, 2010 CFR

...non-voice, non-geostationary mobile-satellite service. 25.142 Section 25.142...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...non-voice, non-geostationary mobile-satellite service. (a) Space station...

2009-10-01

93

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

Code of Federal Regulations, 2010 CFR

...non-voice, non-geostationary mobile-satellite service. 25.142 Section 25.142...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...non-voice, non-geostationary mobile-satellite service. (a) Space station...

2010-10-01

94

Prediction Model for Relativistic Electrons at Geostationary Orbit  

NASA Technical Reports Server (NTRS)

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

Khazanov, George V.; Lyatsky, Wladislaw

2008-01-01

95

Imaging of Geostationary Satellites with the MRO Interferometer  

NASA Astrophysics Data System (ADS)

The emerging field of optical interferometery will enable imaging of geo-stationary satellites at a height of 36,000 meter with a resolution of less than 1 meter. The current generation of optical interferometers has baselines up to 300 meters, which is a factor 100 larger than a 3 meter single dish telescope. Since the spatial resolution scales with wavelength over lambda, the increase in baseline translates directly in an increase in resolving power to see smaller details. The Magdalena Ridge Observatory Interferometer (MROI) will be a 10 element optical interferometer. Each telescope will have a 1.4 meter primary mirror and the maximum distance within the array is close to 400 meters. MROI is currently under construction in the heart of New Mexico and is designed to meet a dual purpose: provide imaging capabilities for space situational awareness, and to provide science capabilities to astronomers. This paper is specifically aimed to demonstrate the capabilities of MROI for imaging geostationary satellites. We have performed simulations of the performance of MROI to image geostationary satellites. These simulations start with a real image of a satellite and a model which uses simple geometric shapes to best represent the real image. This model is fed to a simulator that takes into account the interferometer array configuration and computes the observables using estimates of the errors in the observations and due to the intervening atmosphere. For an imaging interferometer these are the visibilities and closures phases for each available baseline. Finally we use exiting imaging reconstruction algorithms to compute a reconstructed image. To complete the paper with present a discussion on the limitations of these simulations and optical interferometry in general, but will also point to specific issues of interest to the community that these simulations have identified. A separate paper will be presented by the MRO program office that provides an overview of the status of the MRO project.

Bakker, E.; Cormier, C.; Romero, V.

96

Geostationary Atmospheric Observation Satellite Plan in Japan (Invited)  

NASA Astrophysics Data System (ADS)

As emissions of air pollutants in Asia have increased in the past decades accompanying with rapid economic growth of developing countries, Asian regional air pollution has attracted concern from the view of inter-continental and intra-continental long-range transport as well as domestic air quality. Particularly in Japan, transboundary transport of ozone is of recent social concern as one of a cause of increasing trend of near surface ozone concentration. In order to elucidate the transport and chemical transformation processes of air pollution in East Asia, and to attain internationally common understanding on this issue, geostationary atmospheric observation satellite has been proposed in Japan. In 2006, the Japan Society of Atmospheric Chemistry (JSAC) formed Commission on the Atmospheric Environmental Observation Satellite to initiate the discussion. In 2009, Committee on Geostationary Atmospheric Observation Satellite has been formed within JAXA to promote the plan. The proposed satellite consists of a UV/VIS sensor for O3, NO2, HCHO and AOT, and a MIR sensor for O3, CO, HNO3, NO2, H2O and temperature. Targeted spatial and temporal resolutions are ca.10 km and 1-2 hrs, respectively, and focused observation area is northeast Asia potentially covering the southeast and south Asia. Sensitivity analysis and simulation have been made for both the UV/VIS and MIR sensors. Overview of user requirement and the sensitivity analysis for each species will be presented in this talk.

Akimoto, H.; Kasai, Y.; Kita, K.; Irie, H.; Sagi, K.; Hayashida, S.

2009-12-01

97

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)

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

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

2013-04-01

98

Meteosat Third Generation (MTG) Development in the Context of Other Future Geostationary Satellite Observations  

NASA Astrophysics Data System (ADS)

Meteosat Third Generation (MTG) will provide continuity to the European Meteosat observations which are currently performed with Meteosat Second Generation (MSG). MSG takes images in 12 channels with a repeat rate of 15 minutes for the full disk. The future MTG satellites will expand the capabilities far beyond those of MSG with an enhanced imager (FCI) which has 16 channels and a 10 minutes repeat cycle for taking images of the earth's full disk. Especially the novel instruments on MTG a) Lightning Imager (LI), hyperspectral InfraRed Sounder (IRS) and the Ultraviolet-Visible-Near infrared spectrometer (UVN) will provide unprecedented observations. The four instruments will fly on two types of satellites, the imaging satellites (MTG-I) carrying the FCI and LI, and the sounding satellites (MTG-S) carrying the IRS and UVN. The UVN instrument is provided by the European Space Agency (ESA) and the European GMES (Global Monitoring and Environmental Security) programme. The first launch of an imaging satellite is foreseen for 2017. In total the MTG series will serve us with four MTG-I and two MTG-S satellites for about two decades. MTG has been defined to meet the requirements of the user community, i.e. mainly users in Europe. However an interesting perspective is to see the development of the European MTG satellite system in the context of the evolution of the global space-based meteorological satellite system, notably those from geostationary orbit. Satellite agencies in the US, Japan, China and Europe will fly advanced imagers comparable to the FCI on MTG. Therefore there is also scope for a common evolution of the applications of the observations which is being addressed inter alia by CGMS (Coordination Group for Meteorological Satellites). Various agencies will also realise lightning observations from space. Other instruments on MTG (IRS and UVN) can be seen as pioneering realisations in a geostationary orbit of measurements known from polar orbits. This step into the geostationary orbit will enable a high temporal repeat cycle of the observations. For water vapour this means that for the first time observations from space are being made with a temporal resolution commensurate with the spatial resolution. The presentation will present the status of the instrument and applications development. It will also highlight the current cooperation opportunities created by the similarity of the future observing systems.

Schmetz, J.; Stuhlmann, R.; Grandell, J.; Tjemkes, S.; Calbet, X.; Koenig, M.; Rota, S.

2012-12-01

99

The Geostationary Operational Environmental Satellite (GOES) Product Generation System  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

100

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

NASA Astrophysics Data System (ADS)

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

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

101

MEDIUM EARTH ORBIT (MEO) AS A VENUE FOR FUTURE NOAA SATELLITE SYSTEMS  

Microsoft Academic Search

Low Earth orbits (LEO) and Geostationary Earth orbits (GEO) orbits have traditionally been the venues of choice for observations, albeit for very different reasons. LEO provides high spatial resolution with low temporal resolution while GEO provides for low spatial resolution, but high temporal resolution. NOAA utilizes both venues for their environmental satellites. The NOAA Polar-orbiting Operational Environmental Satellites (POES) reside

Gerald J. Dittberner; Andrew J. Gerber; David M. Tralli; Shyam N. Bajpai

102

Satellite orbit determination  

Microsoft Academic Search

Statistical methods for determining satellite trajectories after being put into orbit, after changes in the trajectory and at regular intervals during orbital lifetime are outlined. The least squares method, a differential Gauss-Newton correction algorithm, and interpretation of the results are introduced.

P. Legendre

1984-01-01

103

Investigation of water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

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.

Velden, Christopher

1993-01-01

104

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

SciTech Connect

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.

Weisberg, Joel M., E-mail: jweisber@carleton.edu [Department of Physics and Astronomy, Carleton College, Northfield, MN 55057 (United States); Paglen, Trevor, E-mail: trevor@paglen.com

2012-10-01

105

A Temporal Map in Geostationary Orbit: The Cover Etching on the EchoStar XVI Artifact  

NASA Astrophysics Data System (ADS)

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.

Weisberg, Joel M.; Paglen, Trevor

2012-10-01

106

On the Use of Geostationary Satellites for Climate Feedback Study  

NASA Astrophysics Data System (ADS)

Climate feedback has recently been estimated using satellite data to validate the behavior of current climate models. In order to extract climate feedback strength from data, previous studies have commonly used simple regression of monthly variations in sea surface temperature (SST) with outgoing energy flux anomalies from sun-synchronous satellites. This common methodology needs to be revised when using the observed data with cloud variations. This is because cloud variations occurring independently of SST should not be included as feedbacks to SST. Namely, only pure cloud responses to SST changes should be taken into account as feedbacks to SST. With the sun-synchronous satellite's global energy flux data and SSTs, however, the extraction of cloud response to SST changes is basically limited; the sign of the cross-correlation coefficient between the observed outgoing radiation and SST changes greatly between negative and positive lags between the two time series, and estimation of climate feedback is just subject to selection of the lag. This variable cross-correlation according to lag occurs only in the presence of non-feedback cloud variations. Therefore, estimates of climate feedback will be satisfactory if the significant non-feedback cloud effect on SST is effectively removed. Here we suggest that highly time-resolved data from geostationary satellites are of great use to remove this non-feedback cloud effect. The hourly geostationary data were used to obtain daily SSTs averaged for clear-sky pixels only, so that the non-feedback cloud effects on SST was largely minimized. The clear-sky SSTs, therefore, are only the forcings to cloud variations, but are not the responses to them. To investigate longwave climate feedback to SST, the clear-sky SSTs were compared with outgoing longwave radiation (OLR) values retrieved from recent (January 2008-June 2010) geostationary window channel imagery over tropical western Pacific (TWP; 20°N-20°S, 130°E-170°W). The cross-regression analyses between the domain-averaged values of anomalous OLR and clear-sky SST (deviations from their 90-day centered moving average values) reveal the highest significant correlation at zero lag, and the corresponding regression slope (i.e., change rate of OLR per SST) is about 10 W m-2 K-1. This value is much higher than that for the all-sky SSTs. This result implies that strong negative longwave feedback may be present over TWP.

Choi, Y.-S.; Cho, H.

2012-04-01

107

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

NASA Technical Reports Server (NTRS)

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.

Bowen, Robert R.

1993-01-01

108

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

NASA Astrophysics Data System (ADS)

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.

Bowen, Robert R.

109

A condensed orbital history of Intelsat satellites  

NASA Astrophysics Data System (ADS)

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

Walker, J. G.

1984-03-01

110

Theory of satellite orbit-orbit resonance  

Microsoft Academic Search

On the basis of the strong mathematical and physical parallels between orbit-orbit and spin-orbit resonances, the dynamics of mutual orbit perturbations between two satellites about a massive planet are examined, exploiting an approach previously adopted in the study of spin-orbit coupling. The satellites are assumed to have arbitrary mass ratio and to move in non-intersecting orbits of arbitrary size and

Leon Blitzer; John D. Anderson

1981-01-01

111

Resolution enhancement of passive microwave images from geostationary Earth orbit via a projective sphere coordinate system  

NASA Astrophysics Data System (ADS)

A projective sphere coordinate system in a Wiener filter method to improve the performance of resolution enhancement for microwave radiometer data of a geostationary Earth orbit (GEO) satellite is proposed. Because of the impact of Earth's curvature on remote sensing measurement, the footprint of microwave radiometer is varied while scanning, especially in positions far from subsatellite point. The deconvolution technique used in the microwave radiometer measurements from Earth directly is therefore inaccurate because microwave measurement under this situation cannot be considered as a convolution process. To ameliorate the deconvolution method, a projective spherical coordinate system that enforces the footprint of a microwave radiometer invariant on the surface of a spherical coordinate system in measurements is presented in this article. The performance of the projective coordinate system is evaluated by GEO satellite simulated observations. The simulation results show that the proposed method produces better resolution enhancement, especially in the position where the footprint of the microwave radiometer is seriously influenced by Earth curvature.

Liu, Dawei; Liu, Kai; Lv, Changchun; Miao, Jungang

2014-01-01

112

State estimation for solid apogee motor burning of geostationary satellite  

NASA Astrophysics Data System (ADS)

The results of the state/orbit sequential estimation for a GEO satellite, based on an analysis of real Doppler data for the short-time boost phase of the solid apogee boost motor (ABM), are presented. The estimation was performed for three Japanese satellites. Two stochastic Kalman filters were used for the estimation. It was found that, for a satellite equipped with an offset antenna, the real Doppler data oscillate with a spin period. The estimated state at ABM burnout had good agreement with the drift orbit and attitude determined independently by the ordinary batch method.

Ono, S.; Tomomura, K.; Toyoda, T.

1986-10-01

113

A polar orbit solar power satellite  

NASA Astrophysics Data System (ADS)

A proposal is suggested for placing the solar power satellite (SPS) in a polar elliptic orbit with apogee over the North Pole and placing the rectenna at a high latitude location. The satellite's long dwell time near apogee would allow it to follow the circumpolar motion of the rectenna for a large fraction of an orbit period. The long distance between the rectenna and the consumer could be accommodated by energy storage such as the conversion of elecricity to hydrogen. The advantages of this scheme are that it would confine the microwave beam near the earth to the polar regions which are sparsely populated and it would permit a total power requirement of less than 5 GW for early versions of the SPS, since the geostationary orbit distance would no longer be mandatory.

Freeman, John W., Jr.

114

Space-based sensor management and geostationary satellites tracking  

NASA Astrophysics Data System (ADS)

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.

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

2007-04-01

115

Potential for calibration of geostationary meteorological satellite imagers using the Moon  

USGS Publications Warehouse

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.

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

2005-01-01

116

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

NASA Technical Reports Server (NTRS)

Solar electric propulsion (SEP) technology is currently being used for geostationary satellite station keeping to increase payload mass. Analyses show that advanced electric propulsion technologies can be used to obtain additional increases in payload mass by using these same technologies to perform part of the orbit transfer. In this work three electric propulsion technologies are examined at two power levels for an Atlas 2AS class spacecraft. The on-board chemical propulsion apogee engine fuel is reduced to allow the use of electric propulsion. A numerical optimizer is used to determine the chemical burns which will minimize the electric propulsion transfer time. Results show that for a 1550 kg Atlas 2AS class payload, increases in net mass (geostationary satellite mass less wet propulsion system mass) of 150 to 800 kg are possible using electric propulsion for station keeping, advanced chemical engines for part of the transfer, and electric propulsion for the remainder of the transfer. Trip times are between one and four months.

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

1995-01-01

117

Satellite orbits: Plot routines  

NASA Astrophysics Data System (ADS)

Routines for plotting satellite orbits for the Waves in Space Plasmas shuttle-borne experiment are presented. The principles of virtual device coordinate text are outlined. The programs are written in C language on the HP-UX operating system and the Starbase graphics package.

Olsson, Pelle

1987-02-01

118

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

National Technical Information Service (NTIS)

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 ...

A. D. Little D. O. Neil G. W. Sachse J. Fishman A. J. Krueger

1997-01-01

119

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

National Technical Information Service (NTIS)

Solar electric propulsion technology is currently being used for geostationary satellite station keeping. Analyses show that electric propulsion technologies can be used to obtain additional increases in payload mass by using them to perform part of the o...

S. R. Oleson R. M. Myers C. A. Kluever J. P. Riehl F. M. Curran

1997-01-01

120

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

Code of Federal Regulations, 2010 CFR

...satellite systems and non-voice, non-geostationary satellite...MHz band. (a) A non-voice, non-geostationary...and its directors, officers, employees, affiliates, agents and subcontractors...an interruption of its non-voice, non-geostationary...

2009-10-01

121

Surface Solar Radiation from Geostationary Satellites for Renewable Energy  

NASA Astrophysics Data System (ADS)

Solar radiation available at the surface has been routinely derived in real time from Geostationary Operational Environmental Satellite (GOES) data at the National Oceanic and Atmospheric Administration (NOAA), National Environmental Satellite, Data and Information Service (NESDIS) in a processing system known as the GOES Surface and Insolation Product (GSIP) system. The GSIP system has recently been upgraded to provide retrievals experimentally at a spatial resolution of ~ 4 km. The planned rapid observations (5-15 minutes) from the Advanced Baseline Imager (ABI) on the upcoming GOES-R satellite will enhance the capabilities realized in the current GCIP for solar resources where frequent observations of solar radiation reaching the surface are essential for planning and load management. The algorithms used in GSIP and with ABI are based on radiative transfer, represented in look-up-tables, and internally retrieve clear-sky and cloudy-sky transmittances (GSIP), or use atmospheric and surface parameters derived independently from multispectral radiances (ABI) for calculating these transmittances. Tests, performed using the Moderate Resolution Imaging Spectroradiometer (MODIS) data, have shown that the ABI algorithm is superior to the GSIP algorithm. The algorithms are designed to provide basic radiation budget products (e.g., total solar irradiance at the surface), as well as products specifically needed in the solar energy sector (average, midday and clear-sky insolation, clear-sky days, diffuse and direct normal radiation, etc.). The accuracy of surface solar radiation retrievals are assessed using long-term GOES and MODIS satellite data and surface measurements at the Surface Radiation (SURFRAD) network.

Laszlo, I.; Kondratovich, V.; Liu, H.

2011-12-01

122

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

NASA Astrophysics Data System (ADS)

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.

Rajaram, G.; et al.

2006-11-01

123

Fuzzy Logic Techniques for Rendezvous and Docking of Two Geostationary Satellites.  

National Technical Information Service (NTIS)

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 ...

G. Ortega

1995-01-01

124

Investigations on Ionospheric Electron Content and Electron Density Irregularities at Low Latitudes with Geostationary Satellites.  

National Technical Information Service (NTIS)

The report embodies the results of continuous measurements of ionospheric electron content and scintillations obtained for the first time with a geostationary satellite over the Indian subcontinent. The observations near the crest of the equatorial anomal...

J. N. Bhar S. Basu A. Das Gupta B. K. Guhathakurta G. N. Bhattacharyya

1976-01-01

125

GOES (Geostationary Operational Environmental Satellite) I/M Image Navigation and Registration.  

National Technical Information Service (NTIS)

Image Navigation and Registration (INR) is the system that will be used on future Geostationary Operational Environmental Satellite (GOES) missions to locate and register radiometric imagery data. It consists of a semiclosed loop system with a ground-base...

J. L. Fiorello I. H. Oh K. A. Kelly L. Ranne

1989-01-01

126

Phase and Amplitude Scintillation Statistics at 244 MHz from Goose Bay Using a Geostationary Satellite.  

National Technical Information Service (NTIS)

Phase and amplitude scintillation measurements made at 244 MHz from Goose Bay using the geostationary satellite Fleetsat are presented. An extended dynamic range receiver with an extremely stable local oscillator measured the phase variations with the pre...

S. Basu S. Basu R. C. Livingston E. MacKenzie H. E. Whitney

1982-01-01

127

Investigation of water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

128

Use of Geostationary Satellite Images for Interactive Meteorological Analysis.  

NASA Astrophysics Data System (ADS)

The southern oceans are data-sparse regions and this is especially true for the middle-latitude and sub -Antarctic zones. To obtain a better meteorological data coverage full use must be made of available geostationary satellite data. Data received from Meteosat II, which views the Atlantic Ocean has been available since June 1981 and is available for analysis of the charts of the tropical and middle latitude zones of this ocean. The Man Computer Interactive Data Access System (MCIDAS) provides the means to display and manipulate Meteosat II images. This motivated the development of the Bogus Using Meteosat MCIDAS System (BUMMS). The BUMMS is capable of displaying a meteorological field superimposed over a Meteosat II image, both being transformed to polar stereographic coordinates. Bogus (pseudo) data are entered via the video display, followed by execution of a revised 1000-300 mb thickness analysis and the corresponding field of omega values obtained from a two-level omega equation model. The 1000-300 mb thickness field is interactively modified by the BUMMS until agreement is obtained with the cloud features displayed by the satellite image. Omega equation vertical velocities are used to verify the fit between the thickness field and the cloud features. The BUMMS operate well within the time constraints imposed by the operational procedure. Modifications to the thickness field are introduced by applying Satellite Image Analysis Rules (SIAR) consisting of 10 guidelines based on sound meteorological theory. Seven case studies are discussed. In each case the thickness field is modified using the SIAR. The modified thickness field forms the basis of a new 10-level analysis which becomes the input to a Primitive Equation Nested Model (PENEST). Prognostic 36-hour output from this model is compared with a verification analysis as well as the original prognoses. Results indicate positive improvement in the prognoses using the BUMMS procedure and the SIAR. Full operational implementation of the BUMMS can be recommended.

van Heerden, Johan

129

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)

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.

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

2013-01-01

130

Low Earth Orbit satellite/terrestrial mobile service compatibility  

NASA Technical Reports Server (NTRS)

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.

Sheriff, Ray E.; Gardiner, John G.

1993-01-01

131

Space-based passive radar enabled by the new generation of geostationary broadcast satellites  

Microsoft Academic Search

In this paper we investigate the possibility to develop a passive radar system for mid-range air target surveillance using, as illuminator of opportunity, a high EIRP level geostationary broadcast transmitter. These satellites are being introduced recently for Satellite Mobile Digital TV broadcast purpose. Since they are designed to allow mobile users to receive satellite TV without large antennas, a sufficiently

D. Cristallini; M. Caruso; P. Falcone; D. Langellotti; C. Bongioanni; F. Colone; S. Scafe; P. Lombardo

2010-01-01

132

Superposed epoch analysis of magnetospheric substorms using solar wind, auroral zone, and geostationary orbit data sets  

SciTech Connect

A primary goal in solar wind-magnetosphere studies is to understand how and what role the solar wind plays in controlling the temporal sequence of events during substorms at many widely separated regions within the magnetosphere. Here, the average, correlated behavior of definitive solar wind, auroral zone, and geostationary orbit parameters during isolated substorms is examined. High time resolution (1 min) measurements of two solar wind quantities: B/sub z/ and VB/sub s/, two auroral electrojet indices: AE and AL, and three parameters which define the energetic (30 to 300 keV) electron distribution at geostationary orbit from 13 events are analyzed by using the superposed epoch technique. The zero epoch time used to organize the analyses were defined by the time of energetic electron injection at geostationary orbit. The average variations of the auroral zone and geostationary orbit parameters in relation to the solar wind are discussed in context of the three phase (growth, expansion, and recovery) model of substorms. Notably, we find an approximate 6 minute time lag of expansion phase onset at geostationary orbit relative to time of expansion phase onset in the auroral zone. A possible explanation for this time lag is briefly discussed. 14 refs., 8 figs., 1 tab.

Bargatze, L.F.; Baker, D.N.; McPherron, R.L.

1985-01-01

133

Mission Analysis of Spinning Systems for Transfers from Low Orbits to Geostationary  

Microsoft Academic Search

The paper analyzes the use of spaceborne spinning tethers for a reusable system to transfer payloads with a mass up to 4000 kg from low orbits to geostationary. The study indicates that a two-stage system is lighter than a single-stage tethered system with present day tether materials. A first stage in low orbit and a second stage in medium Earth

E. C. Lorenzini; M. L. Cosmo; M. Kaiser; M. E. Bangham; D. J. Vonderwell; L. Johnson

2000-01-01

134

47 CFR 101.145 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2010 CFR

... (d) Methods for calculating the azimuths to be avoided may be found in: CCIR Report No. 393 (Green Books), New Delhi, 1970; in âRadio-Relay Antenna Pointing for controlled Interference With Geostationary-Satellitesâ by C....

2010-10-01

135

47 CFR 101.145 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2010 CFR

... (d) Methods for calculating the azimuths to be avoided may be found in: CCIR Report No. 393 (Green Books), New Delhi, 1970; in âRadio-Relay Antenna Pointing for controlled Interference With Geostationary-Satellitesâ by C....

2009-10-01

136

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

NASA Technical Reports Server (NTRS)

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.

Blaney, K.; Thienel, C.

1991-01-01

137

focusCloseAp: A Cost-efficient, Generic Product for Collision Risk Assessment for Large Fleets of Geostationary Satellites  

Microsoft Academic Search

The risk of collision of a geostationary satellite with uncontrolled debris or other satellites has been continuously increasing over the last decades. It is currently estimated to be above 1% over the 13 years of a mission's lifetime. Given the high costs associated with such potentially catastrophic event (e.g. platform value, revenue, liability, image) more and more geostationary satellite operators

Gonzalo García; Luis Martín

138

Determining diurnal variations of land surface emissivity from geostationary satellites  

NASA Astrophysics Data System (ADS)

Infrared (IR) land surface emissivity (LSE) with a high temporal and spatial resolution is very important for deriving other products using IR radiance measurements as well as assimilating IR radiances in numerical weather prediction (NWP) models over land. Retrieved from various satellite instruments, many LSE databases are available for operational and research use. Most are updated only monthly; assuming emissivity does not change within the month. However, laboratory measurements have shown that emissivity increases by 1.7% to 16% when soil moisture content becomes higher, especially in sandy soils in the 8.2-9.2 ?m range. And a clearly defined wave-like diurnal pattern of decreasing surface soil moisture during the day and recovery (or increased soil moisture) at night was observed. Therefore, it is expected that LSE possesses a diurnal wave-pattern variation with low values during day time and high values during nighttime. The physically based GOES-R ABI LSE algorithm uniquely exploits the geostationary satellites' high temporal resolution. The algorithm was developed and applied to the radiance measurements from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) on the Meteosat Second Generation (MSG) Meteosat-8/9. The results over the Sahara Desert show that 8.7?m emissivity has a significant diurnal wave-pattern variation, with high values during nighttime and low values during day time. 10.8?m emissivity also shows a similar diurnal variation, but with a smaller amplitude compared to 8.7 ?m. 12.0 ?m emissivity has an even weaker diurnal variation, and an opposite pattern as 8.7 and 10.8 ?m. Evidence is provided to demonstrate that the SEVIRI LSE diurnal wave-pattern variations are real, not artifacts from the retrieval algorithm. The impacts of diurnal variations of errors in GFS forecast (temperature and moisture profiles) and in land surface temperature (LST) are analyzed; they are found to be minor compared to the LSE diurnal variations shown by SEVIRI.

Li, Zhenglong; Li, Jun; Li, Yue; Zhang, Yong; Schmit, Timothy J.; Zhou, Lihang; Goldberg, Mitchell D.; Menzel, W. Paul

2012-12-01

139

Factors affecting frequency and orbit utilization by high power transmission satellite systems.  

NASA Technical Reports Server (NTRS)

The factors affecting the sharing of the geostationary orbit by high power (primarily television) satellite systems having the same or adjacent coverage areas and by satellites occupying the same orbit segment are examined and examples using the results of computer computations are given. The factors considered include: required protection ratio, receiver antenna patterns, relative transmitter power, transmitter antenna patterns, satellite grouping, and coverage pattern overlap. The results presented indicate the limits of system characteristics and orbit deployment which can result from mixing systems.

Kuhns, P. W.; Miller, E. F.; O'Malley, T. A.

1972-01-01

140

A satellite system synthesis model for orbital arc allotment optimization  

NASA Technical Reports Server (NTRS)

A mixed integer programming formulation of a satellite system synthesis problem if presented, which is referred to as the arc allotment problem (AAP). Each satellite administration is to be allotted a weighted-length segment of the geostationary orbital arc within which its satellites may be positioned at any longitudes. The objective function maximizes the length of the unweighted arc segment allotted to every administration, subject to single-entry co-channel interference restrictions and constraints imposed by the visible arc for each administration. Useful relationships between special cases of AAP and another satellite synthesis problem are established. Solutions to two example problems are presented.

Reilly, Charles H.

1987-01-01

141

Aqua satellite orbiting the Earth  

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...

142

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

Code of Federal Regulations, 2013 CFR

...Time sharing between NOAA meteorological satellite systems and non-voice, non-geostationary satellite systems in the 137-138 MHz band. ...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards...

2013-10-01

143

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

Code of Federal Regulations, 2010 CFR

...Time sharing between NOAA meteorological satellite systems and non-voice, non-geostationary satellite systems in the 137-138 MHz band. ...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards...

2010-10-01

144

Geostationary Environment Monitoring Spectrometer(GEMS) onboard MP-GEOSAT (Multi Purpose Geostationary Satellite) over Asia-Pacific region  

NASA Astrophysics Data System (ADS)

National Institute of Environmental Research(NIER), Ministry of Environment, Rep. of Korea is planning GEMS (Geostationary Environment Spectrometer) program to be launched in 2017-2018 onboard a geostationary satellite, MP-GEOSAT of KARI(Korea Aerospace Research Institute). GEMS is a scanning UV-Visible Spectrometer to monitor trans-boundary pollution events in Asia-Pacific region, together with ABI(Advanced Baseline Imager) and GOCI-2 (Geostationary Ocean Color Imager). GEMS is to monitor the distribution of tropospheric O3, NO2, SO2, HCHO, and aerosol in Asia, which is very important region to understand the air quality problems in both regional and global scale. Furthermore, it is essential to monitor air pollution with measurements of meteorological variables for better understanding. This mission is expected to improve the monitoring capability of trans-boundary air pollution events and the accuracy of its forecasting through hourly observation from GEO. Constellation of the MP-GEOSAT with GEOCAPE in America and Sentennial-4 in Europe with launch in 2017- 2018 period can results in great synergistic outcomes including enhancing significantly our understanding in globalization of tropospheric pollution.

Lee, S.; Hong, Y.; Song, C.; Lee, M.; Ryoo, S.; Kim, J.; Yong, S.; Bhartia, P. K.; Park, R.; Woo, J.; Kim, Y. J.; Song, C. H.; Kim, J. H.; Lee, K.; Ho, C.; Park, S. K.; Lee, Y.; Lee, J.; Kim, M.; Eom, Y.; Hong, J.

2009-12-01

145

Simulation experiments for testing the assimilation of geostationary satellite temperature retrievals into a numerical prediction model  

NASA Technical Reports Server (NTRS)

A simulation experiment is presented which tests a procedure that assimilates temperature soundings from geostationary satellites using a method developed by Gal-Chen (1983). The simulation is used to decide whether the increased temporal resolution of geostationary satellite data can be used to improve numerical simulation of a baroclinically unstable wave, and to assess the impact of gaps in the satellite sounding fields on the model simulations. Background information on the simulation experiment is presented, including discussion of the variational approach utilized, the numerical model, updating procedures, and control run. The simulation results indicate that, for the case of a baroclinically unstable wave, considerable improvements in the short-range forecast may be realized if geostationary satellite data are inserted with a frequency near 1 hr during a 6 hr analysis cycle compared with a single insertion.

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

1986-01-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

147

Geostationary Satellite Observations of Gulf Stream Meanders: Infrared Measurements and Time Series Analysis  

Microsoft Academic Search

The infrared capabilities of the Geostationary Operational Environmental Satellite (Goes) are analyzed to obtain multiyear time histories of Gulf Stream meanders. Radiative transfer calculations using monthly mean profiles of atmospheric temperature and moisture are shown to overestimate cloud-free equivalent soundings by 2-5 K. A simple relation is derived between temperature at the satellite, sea surface temperature, and transmissivity of the

George A. Maul; P. Webb deWitt; Alan Yanaway; Stephen R. Baig

1978-01-01

148

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

149

Status of CNES optical observations of space debris in geostationary orbit  

Microsoft Academic Search

Ground observation of space debris in geostationary orbit (GEO) or close to it is not feasible with radar facilities. Optical systems using a telescope and a CCD camera are effective solutions for such a GEO survey because objects remain fixed with report to the Earth. The photons can be cumulated during the exposure time, thus allowing observing faint objects. CNES

F. Alby; B. Deguine; I. Escane

2002-01-01

150

The use and abuse of the geostationary orbit  

NASA Astrophysics Data System (ADS)

The development and use of the GEO are reviewed, and prospects for its future use are discussed. Recent developments concerning broadcasting and meteorological satellites in the GEO and in mobile and fixed satellite services are addressed. The main issues at the upcoming International Conference WARC ORB '88 are examined, stressing allotment planning for satellite communications bands and improved procedures for coordinating satellite communications.

Jansky, Donald M.

151

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

NASA Astrophysics Data System (ADS)

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 Ciência e Tecnologia do Segundo Quadro Comunitário de Apoio.

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

152

Phase and amplitude scintillation statistics at 244 MHz from Goose Bay using a geostationary satellite  

NASA Astrophysics Data System (ADS)

Phase and amplitude scintillation measurements made at 244 MHz from Goose Bay using the geostationary satellite FLEETSAT are presented. An extended dynamic range receiver with an extremely stable local oscillator measured the phase variations with the precision of a coherent system subject to certain limitations. The data were obtained for a 10-month period in 1979 during a high sunspot epoch to extend the limited temporal coverage of orbiting Wideband satellite data. The report presents scintillation statistics in the manner required for communications system planning. The nighttime phase scintillations showed maximum occurrence during the spring and increased greatly in relation to the amplitude scintillations during times of significant magnetic activity. The increase of phase scintillations in relation to amplitude scintillations was attributed to an enhanced ionospheric drift during times of magnetic disturbances. The phase spectral index of the FLEETSAT data was found to be larger than that determined from Wideband data. To further our understanding of auroral irregularity generation mechanisms, this report also presents a case study of energetic particle precipitation spectra, the topside thermal density response of such precipitation and the coordinated phase and amplitude perturbation spectra created by such an energy input into the ionosphere.

Basu, S.; Basu, S.; Livingston, R. C.; MacKenzie, E.; Whitney, H. E.

1982-08-01

153

Potential of Geostationary Satellite Observations of CO2 for Constraining Surface Fluxes  

NASA Astrophysics Data System (ADS)

Remote sensing observations of column integrated CO2 concentrations (XCO2) offer unprecedented data coverage making it possible to explore unresolved questions in carbon cycle science. The sun synchronous orbits and spatially sparse soundings of the majority of current and planned satellites represent a challenge for flux estimation. Geostationary satellites could provide a complement to such observations by making it possible to continuously monitor one-third of the Earth gathering frequent and spatially nearly contiguous XCO2 observations. Such a density of data may represent a new frontier for constraining local- to continental-scale carbon processes. Data from satellites using sun synchronous orbits are typically coupled with an atmospheric transport model to trace variations in observed XCO2 to spatiotemporal variability in CO2 fluxes within a Bayesian inverse modeling framework. The sparseness of observations, their diffuse sensitivity to underlying fluxes, and uncertainties in atmospheric transport compound to yield relatively high uncertainties on underlying fluxes. Here we explore the degree to which geostationary observations could be used to constrain regional fluxes of CO2 and whether the high frequency and high spatial density of the observations would make it possible to rely on simpler 'mass balance' tools (attributing the change in XCO2 over a given region to a net carbon surface flux) for quantifying fluxes. Several sources of uncertainty would limit the precision and accuracy of such flux estimates. Arguably, chief among these are (1) the retrieval algorithm uncertainties, (2) any spatial correlation in the retrieval errors, (3) data gaps due to geophysical limitations, and (4) errors incurred by not accounting for net advection of CO2 via atmospheric transport. Here we systematically explore the individual and combined impacts of these uncertainties. We explore the impact of the first three types of uncertainties on the ability to quantify average XCO2 over a region using geostatistical block kriging. We explore the impact of advection using a geostatistical quantification of the expected gradient in XCO2 in the advected air mass. Finally we translate the total impact of these XCO2 uncertainties into uncertainties in net flux. Results indicate that the precision in XCO2 at regional scales is well above thresholds cited for space-based observations (e.g., Miller et al. 2007; Rayner and O'Brien 2001) as needed for improving flux characterization. Lateral advection and any spatial correlations in retrieval errors (equivalent to the idea of local biases) dominate the overall error budget, highlighting the importance of high frequency observations and of minimizing any correlations in retrieval errors. Overall, we find that high-density XCO2 data would greatly advance monitoring of CO2 fluxes even at moderate temporal and spatial scales. Future space-based missions involving geostationary satellites could drastically reduce CO2 flux uncertainties helping to address fundamental gaps in our understanding of the global carbon cycle.

Hoffman, M. A.; Michalak, A. M.

2013-12-01

154

Study of the optimization of satellite system design for transfer orbit  

Microsoft Academic Search

Geostationary transfer orbit (GTO) characteristics of former geosynchronous satellites; satellite configurations as to GTO requirements; telemetry and telecommand, thermal, power, and attitude control subsystems as to stabilization modes and GTO constraints; and apogee injection strategies (single\\/multiple burn, steering law) were reviewed. The investigations were confined to 2 Ariane 4 payload classes (2500 kg in GTO, dual-launch and 4200 kg in

Baetz; K. Fetzer; W. Fink; H. Hufnagel; H. Kellermeier; Kleinau; W. Mueller; H. Chalmers

1983-01-01

155

47 CFR 25.260 - Time sharing between DoD meteorological satellite systems and non-voice, non-geostationary...  

Code of Federal Regulations, 2010 CFR

...satellite systems and non-voice, non-geostationary satellite...15-401 MHz band. (a) A non-voice, non-geostationary mobile-satellite...and its directors, officers, employees, affiliates, agents and subcontractors...an interruption of its non-voice, non-geostationary...

2010-10-01

156

47 CFR 25.260 - Time sharing between DoD meteorological satellite systems and non-voice, non-geostationary...  

Code of Federal Regulations, 2010 CFR

...satellite systems and non-voice, non-geostationary satellite...15-401 MHz band. (a) A non-voice, non-geostationary mobile-satellite...and its directors, officers, employees, affiliates, agents and subcontractors...an interruption of its non-voice, non-geostationary...

2009-10-01

157

Geostationary satellite positioning by DLR/GSOC operations and management methods  

NASA Technical Reports Server (NTRS)

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.

Brittinger, Peter

1994-01-01

158

Improved Finite Impulse Response Filters for Enhanced Destriping of Geostationary Satellite Data  

Microsoft Academic Search

The visible infrared spin scan radiometer (VISSR) common to many geostationary satellites produces visible wavelength data contaminated with stripes. The stripes affect the usefulness of the data in quantitative studies. This paper briefly reviews the cause of the striping and then develops a tapered window finite impulse response (FIR) filter and a constrained least squares FIR filter. Both filters minimize

James J. Simpson; James R. Stitt; David M. Leath

1998-01-01

159

Providing differentiated service to TCP flows over bandwidth on demand geostationary satellite networks  

Microsoft Academic Search

The elasticity of transmission control protocol (TCP) traffic complicates attempts to provide performance guarantees to TCP flows. The existence of different types of networks and envi- ronments on the connections' paths only aggravates this problem. In this paper, simulation is the primary means for investigating the specific problem in the context of bandwidth on demand (BoD) geostationary satellite networks. Proposed

Merkourios Karaliopoulos; Rahim Tafazolli; Barry G. Evans

2004-01-01

160

A novel approach for optimizing packet access schemes in non-geostationary satellite systems  

Microsoft Academic Search

This paper deals with an optimized packet access scheme depending on traffic load conditions that is able to support efficiently three traffic classes (voice, Web interactive and short messages) in non-geostationary mobile satellite systems. We adopt the equilibrium point analysis in order to study the stability of our scheme. This allows identifying optimal values for the protocol control parameters. Extensive

Giovanni Giambene; Carlo Ortolani; Enrico Zoli

2003-01-01

161

General relativity and satellite orbits  

NASA Technical Reports Server (NTRS)

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.

Rubincam, D. P.

1975-01-01

162

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)

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.

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

163

Precise orbit determination of Beidou Satellites at GFZ  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

164

The Geostationary Earth Radiation Budget Project  

Microsoft Academic Search

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

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

2005-01-01

165

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

166

Satellite services and orbital retrieval  

NASA Technical Reports Server (NTRS)

Within the capabilities of the Space Shuttle Orbiter, a broad range of services which can be made available to the satellite user community as summarized. Payload deployment, close proximity retrieval, and a number of other mission related functions are discussed. The focus here is on close proximity retrieval and retrieval of payloads in higher energy low Earth orbits.

Adornato, R. J.

1985-01-01

167

A feasibility study for the monitoring of diurnal variations of the tropospheric NO2 over Tokyo from a geostationary satellite  

NASA Astrophysics Data System (ADS)

Nitrogen oxides (NOx = NO + NO2 ) are anthropogenic air pollutants mainly emitted from fossil fuel combustion sources. The long-term evolution of the tropospheric NO2 has been monitored through space-borne sensors such as GOME, SCIAMACHY, OMI and GOME-2, since the mid-1990s. However, these measurements were always taken at the same local time due to the sun-synchronous orbits of the satellite platforms used. Because NOx has a diurnal variation, measurements at various local times are needed for proper characterization of NOx distribution and chemistry. A geostationary orbit enables continuous measurements throughout the day, but the requirements for sensor specification become much more severe than for low-earth orbit sensors because of the weaker intensity of light coming from the Earth's atmosphere. We have conducted a feasibility study for the geostationary monitoring of diurnal variations of the tropospheric NO2 over Tokyo. Using NO2 fields from a chemical model, synthetic spectra were created by a radiative transfer model, SCIATRAN for various scenarios. We then performed a Differential Optical Absorption Spectroscopy analysis to retrieve NO2 slant column densities (SCDs) and to estimate the precision of the retrieved SCDs. In this context, we also discuss the effect of stratospheric changes of NO2 and uncertainties in surface reflectivity on the retrieval.

Noguchi, Katsuyuki; Richter, Andreas; Bovensmann, Heinrich; Hilboll, Andreas; Burrows, John P.; Irie, Hitoshi; Hayashida, Sachiko; Morino, Yu

168

Estimation of regional evapotranspiration over the North China Plain using geostationary satellite data  

NASA Astrophysics Data System (ADS)

Data from the first operational Chinese geostationary satellite Fengyun-2C (FY-2C) satellite are applied in combination with Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products for the assessment of regional evapotranspiration over the North China Plain. The approach is based on the improved triangle method, where the temperature-vegetation index space includes thermal inertia. Two thermal infrared channels from FY-2C are used to estimate surface temperature (Ts) based on a split window algorithm originally proposed for the MSG-SEVIRI sensor. Subsequently the high temporal resolution of FY-2C data is exploited to give the morning rise in Ts. Combined with the 16 days composite MODIS vegetation indices product (MOD13) at a spatial resolution of 5 km, evaporative fraction (EF) is estimated by interpolation in the ?Ts-NDVI triangular-shaped scatter space. Finally, regional actual evapotranspiration (ET) is derived from the evaporative fraction and available energy estimated from MODIS surface albedo products MCD43. Spatial variations of estimated surface variables (Ts, EF and ET) corresponded well to land cover patterns and farmland management practices. Estimated ET and EF also compared well to lysimeter data collected for the period June 2005-September 2007. The improved triangle method was also applied to MODIS products for comparison. Estimates based on FY-2C products proved to provide slightly better results than those based on MODIS products. The consistency of the estimated spatial variation with other spatial data supports the use of FY-2C data for ET estimation using the improved triangle method. Of particular value is the high temporal frequency of image acquisitions from FY-2C which improves the likelihood of obtaining cloud free image acquisitions as compared to polar orbiting sensors like MODIS.

Shu, Yunqiao; Stisen, Simon; Jensen, Karsten H.; Sandholt, Inge

2011-04-01

169

Low Earth orbit communications satellite  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

170

Debris impact damage and fragmentation of antenna structure in geostationary orbit  

NASA Astrophysics Data System (ADS)

Low velocity impact tests simulating debris collision in geostationary orbit were conducted to investigate structural damage and fragment dispersion. Simple holes were perforated on CFRP shells, while tube elements were either perforated or destroyed depending on the projectile size. Impact produced a dust like cloud consisting of very small particles including more than 1000 particles of larger than 1 mm in size. The velocities of the particles were in the same order as the velocity of the projectile.

Yasaka, Tetsuo; Meguro, Akira; Watanabe, Mitsunobu

1996-05-01

171

Medium Earth Orbit (MEO) as an operational observation venue for NOAA's post GOES-R environmental satellites  

Microsoft Academic Search

Today most operational Earth observing satellites reside in low Earth orbits (LEO) at less than 1,000 km altitude, and in geostationary Earth orbits (GEO) at ~35,800 km altitude. These orbits have been the venues of choice for observations, albeit for very different reasons. LEO provides high spatial resolution with low temporal resolution while GEO provides for low spatial resolution, but

Andrew J. Gerber Jr.; David M. Tralli; Shyam N. Bajpai

2005-01-01

172

Perturbations in orbital elements of a low earth orbiting satellite  

Microsoft Academic Search

The main point of this paper is to evaluate the perturbations in orbital elements of a low Earth orbiting satellite. The outcome of a numerical orbit integration process is the position and velocity vectors of satellite in an inertial coordinate system. The velocity and position vectors are converted into the corresponding orbital elements. Perturbations in a satellite motion affect the

Najafi Alamdari; Nasir Toosi

173

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

NASA Astrophysics Data System (ADS)

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.

Uetsuhara, Masahiko; Hanada, Toshiya

2013-09-01

174

M.E.G.A.L.O.S.: Multimission European geostationary Ariane launched orbital station  

NASA Astrophysics Data System (ADS)

A new configuration of Telecommunication Platform, specifically conceived to meet the requirements of a set of payload packages resulting from a market survey for the next decade European demands, is presented. It is assembled on geostationary orbit, via rendezvous and docking of modules separately launched by Ariane 4. In-orbit growth potential and/or refurbishment derive from the rendezvous and docking capability and M.E.G.A.L.O.S. can be seen as a module of an even more complex structure.

Ravazzotti, M. T.; Festa, A.

175

In-orbit imaging and radiometric performance prediction for flight model Geostationary Ocean Color Imager  

NASA Astrophysics Data System (ADS)

The Geostationary Ocean Colour Imager (GOCI) is a visible band ocean colour instrument onboard the Communication, Ocean, and Meteorological Satellite (COMS) scheduled to be in operation from early 2010. The instrument is designed to monitor ocean water environments around the Korean peninsula in high spatial and temporal resolutions. We report a new imaging and radiometric performance prediction model specifically designed for GOCI. The model incorporates the Sun as light source, about 4000km x 4000km section of the Earth surrounding the Korean peninsula and the GOCI optical system into a single ray tracing environment in real scale. Specially, the target Earth section is constructed using high resolution coastal line data, and consists of land and ocean surfaces with reflectivity data representing their constituents including vegetation and chlorophyll concentration. The GOCI instrument in the IRT model is constructed as an optical system with realistic surface characteristics including wave front error, reflectivity, absorption, transmission and scattering properties. We then used Monte Carlo based ray tracing computation along the whole optical path starting from the Sun to the final detector plane, for simultaneous imaging and radiometric performance verification for a fixed solar zenith angle. This was then followed by simulation of red-tide evolution detection and their radiance estimation, in accordance with the in-orbit operation sequence. The simulation results prove that the GOCI flight model is capable of detecting both image and radiance originated from the key ocean phenomena including red tide. The model details and computational process are discussed with implications to other earth observation instruments.

Jeong, Soomin; Jeong, Yukyeong; Ryu, Dongok; Kim, Seonghui; Cho, Seongick; Hong, Jinsuk; Kim, Sug-Whan; Youn, Heong Sik

2009-08-01

176

The orbit of Pluto's satellite  

NASA Technical Reports Server (NTRS)

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.

Tholen, D. J.

1985-01-01

177

Monitoring Air Quality from Geostationary Orbit in Asia-Pacific region by MP-GEOSAT (Invited)  

NASA Astrophysics Data System (ADS)

To date, atmospheric chemistry measurements have been carried out by many satellite programs to monitor air quality including O3, NO2, SO2, HCHO, CO including OMI, GOME, SCHIAMACHY, MOPITT, and TES. These measurements have provided extensive dataset to monitor daily to annual changes of pollutant distributions, but are lack of capability in detecting the diurnal variation of pollutant’s concentration thus in providing constraints on their sources. Asia, where both anthropogenic and natural sources of pollutants dominate throughout the year, is an important region to understand tropospheric air pollution in global scale. A scanning UV-Visible Spectrometer, named GEMS (Geostationary Environment Spectrometer) is being planned to be launched in 2017-2018 onboard a geostationary satellite, MP-GEOSAT by KARI(Korea Aerospace Research Institute), together with ABI(Advanced Baseline Imager) and GOCI-2 (Geostationary Ocean Color Imager). Synchronous measurements of air pollutants together with the meteorological variables and ocean color information are expected to contribute to better scientific understanding on the distribution and transboundary transportation of air pollution, and on interactions between meteorology and air chemistry in the Asia-Pacific region. This mission is expected to improve the accuracy of air quality forecasting and reduce current discrepancy between the model and observation. Furthermore, constellation of the MP-GEOSAT with GEOCAPE in America and Sentennial-4 in Europe starting in 2017- 2018 time frame can result in great synergistic outcomes including enhancing significantly our understanding in globalization of tropospheric pollution.

Kim, J.; Park, R.; Bhartia, P. K.; Yong, S.; Song, C.; Hong, Y.; Lee, S.; Ryoo, S.; Lee, M.; Kim, J.; Woo, J.; Kim, Y. J.; Song, C. H.; Kim, J. H.; Lee, K.; Ho, C.; Park, S. K.; Lee, Y.; Lee, J.; Eom, Y.; Suh, A.; Ahn, Y.

2009-12-01

178

Satellite Orbital Interpolation Comparison Methods  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

179

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

NASA Technical Reports Server (NTRS)

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.

Steadman, Karl

1989-01-01

180

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

NASA Technical Reports Server (NTRS)

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).

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

2001-01-01

181

Bit Error Rate Evaluation of a Spectrally Efficient CDMA Scheme for Geostationary Satellite Communications  

Microsoft Academic Search

Spectrally efficient CDMA (SE-CDMA) is a multiple access and modulation scheme proposed for multibeam geostationary communications satellites that provides fixed service directly to the end users. The SE-CDMA is designed to meet the service requirements for high spectral efficiency and low bit error rate (BER) given the on-board power limitations. Its implementation consists of a concatenated Reed-Solomon\\/turbo channel encoder, of

Diakoumis P. Gerakoulis; Evaggelos Geraniotis

2000-01-01

182

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

Microsoft Academic Search

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

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

2007-01-01

183

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

184

Scheme for detection of low clouds from geostationary weather satellite imagery  

NASA Astrophysics Data System (ADS)

A simple and practical scheme for low cloud detection at sea based on geostationary weather satellite data is proposed. The scheme consists of several threshold discrimination tests, and time-consuming procedures are eschewed in order to enable near-real-time analysis. This scheme also minimizes the use of data other than from geostationary weather satellites, leading to a convenient low cloud detection procedure without ancillary data. Careful investigation of the radiative properties of low water clouds from radiative transfer simulation and satellite observations enables full utilization of the characteristics of satellite data and realization of the simple scheme. The threshold values, which should possess high generality, for the discrimination tests are obtained from statistical comparisons of Multi-function Transport Satellite-2 data to grid point value data, which allows for extensive data collection and eliminates the localities and anomalies. Verification by comparisons with radiosonde and lidar on satellite suggests that results obtained from the proposed low cloud detection scheme are reasonable.

Ishida, Haruma; Miura, Kentaro; Matsuda, Teruaki; Ogawara, Kakuji; Goto, Azumi; Matsuura, Kuniaki; Sato, Yoshiko; Nakajima, Takashi Y.

2014-06-01

185

Low Bus Voltage Hydrazine Arcjet System for Geostationary Satellites  

NASA Astrophysics Data System (ADS)

The capabilities of arcjet propulsion systems were recently extended to accommodate operation on the NASDA Data Relay Test Satellite (DRTS) providing a power bus voltage between 31 and 51.5 VDC. This paper summarizes the newly attained qualification status of the MR 512 arcjet system demonstrating the flexibility of the current design. A redesign of the Power Processing Unit (PPU) became necessary as well as a delta-qualification of the thruster to validate spacecraft integration and to provide compliance with the DRTS satellite environmental requirements. Two types of thrusters with different thrust levels were made available to meet mission requirements. The delta-qualification included a pyro-shock test, vibration tests to a higher level than previously tested, and performance mapping beyond the original range. Included in the paper is an assessment of the PPU performance characteristics as well as the discussion of the system operation and system telemetry.

Zube, Dieter M.; Fye, Dan

1998-07-01

186

The Marshall Automated Wind Algorithm for Geostationary Satellite Wind Applications  

NASA Technical Reports Server (NTRS)

The Marshall Automated Wind (MAW) algorithm was developed over a decade ago in support of specialized studies of mesoscale meteorology. In recent years, the algorithm has been generalized to address global climate issues and other specific objectives related to NASA missions. The MAW algorithm uses a tracking scheme which minimizes image brightness temperature differences in a sequence of satellite images to determine feature displacement (winds). With the appropriate methodology accurate satellite derived winds can be obtained from visible, infrared, and water vapor imagery. Typical errors are less than 4 m/s but depend on the quality and control constraints used in post-processing. Key to this success is the judicious use of template size and search area used for tracking, image resolution and time sampling, and selection of appropriate statistical constraints which may vary with image type and desired application. The conference paper and subsequent poster will provide details of the technique and examples of its application.

Jedlovec, Gary J.; Atkinson, Robert J.

1998-01-01

187

Plan of Korean Geostationary Environment Satellite over Asia-Pacific region  

NASA Astrophysics Data System (ADS)

National Institute of Environmental Research(NIER/Ministry of Environment Korea) is planning GEMS (Geostationary Environment Monitoring Spectrometer) program to be launched in 2017-2018 onboard a MP-GEOSAT(Multi-Purpose GEOstationary SATellite) which is supposed to be the successive mission of COMS(Communication, Ocean and Meteorological Satellite). GEMS is a scanning UV-Visible Spectrometer to monitor trans-boundary pollution events in Asia-Pacific region, together with ABI(Advanced Baseline Imager) and GOCI-2 (Geostationary Ocean Color Imager). The objective of GEMS is to provide high resolution atmospheric chemistry measurements, to monitor regional and transboundary events, to understand on interactions between atmospheric chemistry and climate, and to improve chemical weather forecast with constraining hourly emissions and data assimilation of chemical observations. Opportunity of international collaboration with NASA and ESA, for the constellation with the GEMS of Korea, Japanese air quality mission, GEO-CAPE of U.S.A and Sentennial-4 of Europe planned to be launched in 2017- 2020 time frame, which can make great synergistic outcomes for better understanding in global air quality and climate change issues.

Lee, Sukjo; Hong, Youdeog; Song, Chang-Keun; Lee, Joonsuk; Choi, Won-Jun; Kim, Dukrae; Moon, Kyung-Jung; Kim, Jhoon

2010-05-01

188

Studies of lightning data in conjunction with geostationary satellite data  

NASA Technical Reports Server (NTRS)

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.

Auvine, B.; Martin, D.

1985-01-01

189

An Orbiting Standards Platform for communication satellite system RF measurements  

NASA Technical Reports Server (NTRS)

The Orbiting Standards Platform (OSP) is a proposed satellite dedicated to performing RF measurements on space communications systems. It would consist of a quasi-geostationary spacecraft containing an ensemble of calibrated RF sources and field strength meters operating in several microwave bands, and would be capable of accurately and conveniently measuring critical earth station and satellite RF performance parameters, such as EIRP, gain, figure of merit (G/T), crosspolarization, beamwidth, and sidelobe levels. The feasibility and utility of the OSP concept has been under joint study by NASA, NBS, Comsat and NTIA. A survey of potential OSP users was conducted by NTIA as part of this effort. The response to this survey, along with certain trends in satellite communications system design, indicates a growing need for such a measurement service.

Wallace, R. G.; Woodruff, J. J.

1978-01-01

190

A Semi-Empirical Model for Forecasting Relativistic Electrons at Geostationary Orbit  

NASA Technical Reports Server (NTRS)

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

Lyatsky, Wladislaw; Khazanov, George V.

2008-01-01

191

The Solar Dynamics Observatory After Almost Three Years in Geostationary Orbit  

NASA Astrophysics Data System (ADS)

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

Pesnell, W. D.

2012-12-01

192

47 CFR 25.260 - Time sharing between DoD meteorological satellite systems and non-voice, non-geostationary...  

Code of Federal Regulations, 2013 CFR

...Time sharing between DoD meteorological satellite systems and non-voice, non-geostationary satellite systems in the 400.15-401 MHz band...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards...

2013-10-01

193

Upper-Tropospheric Winds Derived from Geostationary Satellite Water Vapor Observations  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

194

Geostationary earth radiation budget  

NASA Astrophysics Data System (ADS)

The Earth Radiation Budget (ERB), the balance between the incoming solar radiation from the sun and the outgoing reflected and scattered solar radiation and the thermal infrared emission from the Earth, provides information on the fundamental energy source of the climate system. To fulfil global coverage and sampling requirements, the ERB measurements have to be made from space. Broad-band measurements are necessary because all spectral regions in both the solar and infrared contribute to the radiative fluxes. Satellite data are used in a wide range of basic studies of the radiative forcing of the climate, such as understanding the effects of variations in trace gases, clouds and the surface. They also provide essential validation for climate models. All such measurements to date have been made from satellites in low earth orbit (LEO). There are strong diurnal variations in the radiation budget, particularly over land, in response to the diurnal variation of solar heating. Four LEO satellites could provide coverage of the diurnal cycle with a temporal resolution of 3 hours. At least hourly measurements are needed to resolve the diurnal cycle of tropical convection properly, and no practicable system of polar orbiting or other LEO satellites can deliver this. From the above, it appears that the only viable solution to the problem of diurnal sampling of the Earth's radiation budget is the inclusion of suitable sensors on the geostationary satellites which would allow for an essentially perfect temporal sampling. Disadvantages include the fact that geostationary satellites are much further from the Earth than polar orbiters, which affects the instrumental design, and each one can only provide a limited coverage of the globe. The Geostationary Earth Radiation Budget instrument (GERB) is a highly accurate visible-infrared radiometer designed to make unique measurements of the outgoing shortwave and longwave components of the Earth's Radiation Budget (ERB) from geostationary orbit. Such measurements have not been achieved previously, and are extremely important, because they will permit a rigorous test of our understanding of the diurnal variations in the ERB: this will enable improved operational weather monitoring and permit further important developments in climate change research. GERB will be launched on the (MSG) geostationary satellite in the year 2000. Both short-wave (0.32 - 4 micrometer) and total (0.32 - 30 micrometer) radiance measurements would be made, with longwave (4 - 30 micrometer) data obtained by subtraction. The accuracy requirements (1% short-wave and 0.5% longwave) are consistent with previous radiation budget measurements. The availability of GERB on MSG will also allow a more accurate calibration of the principal Meteosat Second Generation (MSG) operational sounding instrument, SEVIRI (Spinning, Enhanced Visible and InfraRed Imager).

Mossavati, Ruzbeh; Kellock, Steve; Mueller, Johannes; Harries, J. E.; Murray, J. E.; Sawyer, Eric C.; Caldwell, Martin E.; Oliver, M.; Delderfield, J.; Sandford, Michael C.

1997-12-01

195

Simulation of Precise Offline Satellite Orbit Determination  

Microsoft Academic Search

In this paper we have taken advantages of precise orbit determination of satellite trajectories using offline simulations. Furthermore perturbation forces which make complex motion equations of satellites and cause more complicated satellites trajectories are simulated using Poisson and Lagrange brackets methods. Moreover perturbation forces effects in the satellites motion are investigated and precise position of satellite is estimated. Finally a

Mohammad Bagher Alaee; Hossein Rahmani

2010-01-01

196

THE GEOSTATIONARY EARTH RADIATION BUDGET (GERB) EXPERIMENT: SCIENCE AND APPLICATIONS  

Microsoft Academic Search

ABSTRACT When the first Meteosat Second Generation satellite (MSG-1) was launched in August 2002, it carried an additional instrument, chosen through an Announcement of Opportunity. Named the Geostationary Earth Radiation Budget (GERB) experiment, this instrument will measure the long and shortwave components of the Earth’s radiation budget ,for the first time from ,geostationary ,orbit. This vantage ,point permits ,much higher

J E Russell; J E Harries; J Hanafin; H Brindley; J M Futyan; R P Allan; A Slingo; M A Ringer

197

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)

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.

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

2012-12-01

198

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

NASA Technical Reports Server (NTRS)

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.

Bowen, Robert R.

1990-01-01

199

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

NASA Astrophysics Data System (ADS)

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.

Bowen, Robert R.

200

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

NASA Technical Reports Server (NTRS)

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.

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

201

Errors in orbit determination of artificial satellites  

Microsoft Academic Search

The influence of position measurement errors upon determination of satellite orbital parameters and the effect of errors in orbital parameters on the prediction of satellite positions are numerically evaluated. All calculations refer to a representative number of various trajectories. An expectation window is defined for an area in space in which an investigated satellite may be picked up again one

R. Deriz

1976-01-01

202

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

PubMed

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

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

2014-01-01

203

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

204

Low earth orbit satellite/terrestrial mobile service compatibility  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

205

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

NASA Technical Reports Server (NTRS)

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

Sawitz, P. H.

1975-01-01

206

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

NASA Technical Reports Server (NTRS)

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.

Velden, Christopher S.

1995-01-01

207

Investigation of Thermo-optical Characteristics of Thermo-regulating Covers on Geostationary Orbit  

NASA Astrophysics Data System (ADS)

This report presents the results of an investigation of thermo-optical characteristics, i.e. the total solar absorptance, ?s and solar emittance, ? of thermal control coatings (TCC) exposed to the space environment at a geostationary orbit (GEO). Experiments results from samples that were flown on space vehicles (SV) ``Yamal-100'' and ``Yamal-200'' for 8 and 4 flight years, respectively, are presented here. The results from experiments flown for 6 and 2 flight years were presented in an earlier article [1]. The ?s and V characteristics were measured by a calorimetric method through monitoring the temperatures of the coating samples that were used as microcalorimeters (MC) and a mathematical treatment of the temperature data. The temperature sensors were attached to the back side of the flown samples.

Gorodetsky, A. A.; Borisov, V. A.; Sokolova, S. P.; Naumov, S. F.

2009-01-01

208

Linked Autonomous Interplanetary Satellite Orbit Navigation  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

209

Orbiting Earth  

NSDL National Science Digital Library

This Flash animation contrasts the geostationary versus polar orbits for satellites. For a geostationary orbit, the satellite remains directly above a fixed point at all times; in time with the Earth's rotation, the satellite circles the earth once every 24 hours, continually viewing the same part of Earth. For the polar orbit, the satellite circles over both poles in a constant plane while earth rotates beneath. Earth's rotation exposes different parts of the surface on each orbit. The animation is useful for a discussion on how remote sensing imagery and Global Positioning Systems (GPS) signals are derived. The animation can be paused and rewound to stress important points.

Loomis, Jennifer; Nasa; Earth, Exploring

210

Satellite Constellation Orbit Evaluation (SCORE) Program.  

National Technical Information Service (NTIS)

The objective of this research was to produce a flexible, user-friendly, PC-based computer program that could assist in evaluating satellite constellations. The program would need the capability to graphically display various facets of satellite orbits an...

L. C. Russell

1990-01-01

211

An Analytical Satellite Orbit Predictor (ASOP)  

NASA Technical Reports Server (NTRS)

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.

Starke, S. E.

1977-01-01

212

Orbital Manoeuvres of Chinas Zi Yuan Satellites  

NASA Astrophysics Data System (ADS)

China has launched two satellites in the Zi Yuan programme through to October 2001. The first was the CBERS satellite, developed jointly with Brazil and the second was a domestic satellite which is reportedly being used for reconnaissance work. The orbital behaviour of the two satellites has been completely different and is reviewed in this paper.

Clark, P. S.

213

The orbit-sharing environment for Canadian fixed satellites in the 1990s and beyond  

NASA Astrophysics Data System (ADS)

In 1987, it was recognized that the portion of the geostationary orbit of interest to Canada for its domestic satellites was becoming saturated. At the same time there was a need to accommodate the Anik E series of dual band communication satellites which was not possible under existing orbit-use arrangements. A trilateral arrangement between the USA, Mexico, and Canada was reached in May 1988 defining the shared use of the geostationary satellite orbit and those Ku and C frequency bands currently used by the Anik satellite. The World Administrative Radio Conference (WARC) for the space services held in May, 1988 developed an allotment plan for the upper 6/4 GHz band and the 13/11 GHz band. The Anik series of satellites will face a reduction of the 5 deg spacing of the 1970s to about 3 deg for the Anik E series, with satellites at 3.8 deg spacing interleaved with Mexican MORELOS satellites. Four such positions are available for the Anik E series. Three colocated orbit positions in the 13/11 and upper 6/4 GHz allotment plan are reserved for future Canadian use. In addition, more bandwidth is available.

Bowen, Robert R.; Streibl, Irena

214

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

NASA Technical Reports Server (NTRS)

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.

Ivancic, William D.; Shalkhauser, Mary JO

1992-01-01

215

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

NASA Technical Reports Server (NTRS)

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.

Ivancic, William D.; Shalkhauser, Mary JO

1991-01-01

216

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

NASA Technical Reports Server (NTRS)

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.

Ivancic, William D.

1992-01-01

217

Transport and acceleration of plasma sheet electrons to geostationary orbit (Invited)  

NASA Astrophysics Data System (ADS)

Transport and acceleration of the electrons with energies less than 200 keV from the plasma sheet to geostationary orbit were investigated. These electron fluxes constitute the seed population for the high energy MeV particles in the radiation belts and are responsible for hazardous phenomena such as surface charging. We modeled several quiet and storm events, when the presence of isolated substorms was seen in the AE index. We used the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) with the boundary at 10 Re with Tsyganenko and Mukai moment values for the electrons in the plasma sheet. The output of the IMPTAM modeling was compared to the observed electron fluxes in ten energy ranges (from 5 to 50 keV) measured onboard the AMC 12 geostationary spacecraft by the CEASE II ESA instrument and to LANL data from MPA and SOPA instruments. The behavior of the fluxes depends on the electron energy. IMPTAM model, driven by the observed parameters such as IMF By and Bz, solar wind velocity, number density and dynamic pressure and the Dst index, was not able to reproduce the observed peaks in the electron fluxes when no significant variations are present in those parameters. The variations of the observed fluxes during this non-storm period are due to substorm activity. We introduced the substorm-associated electromagnetic fields by launching several electromagnetic pulses at the substorm onsets during the modeled period. The substorm-associated increases in the observed fluxes can be captured by IMPTAM when substorm-associated electromagnetic fields are taken into account. Modifications of the pulse model used here are needed, especially related to the pulse front velocity and arrival time.

Ganushkina, Natalia

2014-05-01

218

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

219

Automated testing of low-orbiting satellites  

Microsoft Academic Search

This paper describes the hardware, software, and test procedures implemented at a ground station for the automated testing of a polar-orbiting satellite in a low orbit. The satellite passes during the testing were characterized by short visibility times of no more than 18 min and by high rates of change of the link parameters as seen by the ground station.

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

1985-01-01

220

A polar orbit solar power satellite  

Microsoft Academic Search

A proposal is suggested for placing the solar power satellite (SPS) in a polar elliptic orbit with apogee over the North Pole and placing the rectenna at a high latitude location. The satellite's long dwell time near apogee would allow it to follow the circumpolar motion of the rectenna for a large fraction of an orbit period. The long distance

John W. Freeman Jr.

1988-01-01

221

Flow-topography interactions in the northern California Current System observed from geostationary satellite data  

NASA Astrophysics Data System (ADS)

Data from Geostationary Operational Environmental Satellites are used to study the seasonal evolution of temperature fronts in the northern California Current System (CCS), focusing on the interactions with topographic features. Fronts first appear close to the coast in response to upwelling winds, moving offshore with the continuous input of energy to the system. Late in the upwelling season (after July), the upwelling front is persistently found over deeper waters south of Heceta Bank, Oregon, than north of it, suggesting that the equatorward jet separates from the shelf at Heceta Bank. Inshore of the upwelling front, weak gradients are found on the Bank. The interaction of the equatorward flow with Heceta Bank and Cape Blanco, Oregon, farther south, substantially increases the mesoscale activity and oceanic frontal habitat downstream to the south in the CCS, where fronts are persistently found greater than 100 km from the coast.

Castelao, Renato M.; Barth, John A.; Mavor, Timothy P.

2005-12-01

222

A feasibility study for the monitoring of diurnal variations of the tropospheric NO2 over Tokyo from a geostationary satellite  

NASA Astrophysics Data System (ADS)

The long-term evolution of tropospheric NO2 has been observed by space-borne sensors such as GOME, SCIAMACHY, OMI and GOME-2 since the mid-1990s. However, these measurements were always taken at fixed local times as the sun-synchronous orbits are used. Because tropospheric NO2 shows substantial diurnal variations due to variations in the photochemistry, meteorology and surface emissions, measurements at various local times are needed to understand the NO2 distribution and its related chemistry and sources. Measurements from a geostationary orbit provide observations of the diurnal variation, because this orbit enables continuous measurements throughout the day. On the other hand, the requirements for sensor specification in a geostationary orbit become much more severe than for low-earth orbit sensors due to the weaker intensity of light coming from the Earth's atmosphere. In this context, we have conducted a feasibility study for the geostationary monitoring of diurnal variations of the tropospheric NO2 over Tokyo. Using NO2 fields from a chemical transport model, synthetic spectra were created by a radiative transfer model, SCIATRAN, for various geometric and seasonal scenarios. We then performed a Differential Optical Absorption Spectroscopy analysis to retrieve NO2 slant column densities (SCDs) and to estimate the precision of the retrieved SCDs. The results of the retrieval simulation showed that we need signal-to-noise ratios (SNR) better than 500 to detect the diurnal variation of the NO2 SCD (~1E16 /cm2). The simulation also showed that the precision of the SCDs would be 2-6% with the sensor specification (spatial resolution of 5km and time resolution of 1hr) as currently discussed for geostationary instruments of GMAP-ASIA (Geostationary Mission for Meteorology and Air Pollution) in Japan. We also discuss the effect of uncertainties in surface reflectivity (albedo) on the retrieval.

Noguchi, K.; Irie, H.; Morino, Y.; Hayashida, S.; Richter, A.; Bovensmann, H.; Hilboll, A.; Burrows, J. P.

2010-12-01

223

Volcanic Ash and SO2 plume retrievals at Mt. Etna using polar and geostationary satellite measurements  

NASA Astrophysics Data System (ADS)

Mt. Etna (37.45°N, 15.01°E), located in the eastern part of Sicily (Italy), is one the major degassing volcanoes in the world. Its general quiescent state is periodically interrupted by eruptive crises, during which significant ash and SO2 emissions can reach the area surrounding the volcano, causing problems to the population and in particular to air traffic (Catania and Reggio Calabria airports are nearby). Because SO2 and ash are often emitted by an erupting volcano simultaneously, and as the winds can transport these substances together, a measurement of SO2 can be used, in some circumstances, as a proxy for ash. This is particularly important for aviation, when the volcanic debris has been transported over long distances and the satellite-based ash detection signal is weak. In this work the Thermal InfraRed (TIR) measurements of different polar and geostationary satellites instruments as NOAA-AVHRR, NASA-MODIS and MSG-SEVIRI will be used to retrieve simultaneously ash and SO2 from Mt. Etna volcanic plume. The polar measurements ensure bigger ground pixels resolution while geostationary measurements ensure bigger repetition time then the possibility to follow the volcanic eruption evolution. The volcanic ash detection and retrievals (aerosol optical thickness at 0.55 mm, effective radius and ash mass) are carried out by means of the Brightness Temperature Difference (BTD) technique using the TIR channels centred around 11 and 12 micron. The SO2 is carried out by using a best weighted least squares fit method using the channels centered around 8.7 micron. The simulated TOA radiance Look-Up Table (LUT) needed for both the SO2 column abundance and the ash retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. The ash impact on SO2 retrieval has been also investigated. As test case the Mt. Etna eruptive events in 2006 and 2007 have been analyzed.

Corradini, S.; Merucci, L.; Spinetti, C.; Silvestri, M.; Musacchio, M.; Piscini, A.; Buongiorno, M.

2009-12-01

224

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

NASA Astrophysics Data System (ADS)

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 (0.6?m), NIR008 (0.8?m) and NIR016 (1.6?m). 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.

Reuter, Maximilian

2013-04-01

225

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

Federal Register 2010, 2011, 2012, 2013

...procedures between NGSO FSS space-to-Earth operations and existing fixed service...procedures between NGSO FSS space-to-Earth operations and existing fixed service...prior to the licensing and operation of an earth station, to identify and implement...

2010-04-05

226

Nowcasting Aircraft Icing Conditions in Moscow Region Using Geostationary Meteorological Satellite Data  

NASA Astrophysics Data System (ADS)

Nowadays the Main Aviation Meteorological Centre in Moscow (MAMC) provides forecasts of icing conditions in Moscow Region airports using information of surface observation network, weather radars and atmospheric sounding. Unfortunately, satellite information is not used properly in aviation meteorological offices in Moscow Region: weather forecasters deal with satellites images of cloudiness only. The main forecasters of MAMC realise that it is necessary to employ meteorological satellite numerical data from different channels in aviation forecasting and especially in nowcasting. Algorithm of nowcasting aircraft in-flight icing conditions has been developed using data from geostationary meteorological satellites "Meteosat-7" and "Meteosat-9". The algorithm is based on the brightness temperature differences. Calculation of brightness temperature differences help to discriminate clouds with supercooled large drops where severe icing conditions are most likely. Due to the lack of visible channel data, the satellite icing detection methods will be less accurate at night. Besides this method is limited by optically thick ice clouds where it is not possible to determine the extent to which supercooled large drops exists within the underlying clouds. However, we determined that most of the optically thick cases are associated with convection or mid-latitude cyclones and they will nearly always have a layer where which supercooled large drops exists with an icing threat. This product is created hourly for the Moscow Air Space and mark zones with moderate or severe icing hazards. The results were compared with mesoscale numerical atmospheric model COSMO-RU output. Verification of the algorithms results using aircraft pilot reports shows that this algorithm is a good instrument for the operational practise in aviation meteorological offices in Moscow Region. The satellite-based algorithms presented here can be used in real time to diagnose areas of icing for pilots to avoid.

Barabanova, Olga

2013-04-01

227

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

NASA Astrophysics Data System (ADS)

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.

Oyoshi, K.; Tamura, M.

2009-12-01

228

Orbital motion of the solar power satellite  

Microsoft Academic Search

A study on the effects of solar radiation pressure on the SPS orbit is documented. It was shown that the eccentricity of the orbit can increase from initially being zero. The SPS configuration is primarily considered but the results are applicable to any geosynchronous satellite that resembles a flat surface continually facing the sun. The orbital evolution of the SPS

O. F. Graf Jr.; O. F. Jr

1977-01-01

229

CELEST Computer Program for Computing Satellite Orbits.  

National Technical Information Service (NTIS)

The Celest Computer Program uses raw Doppler data to determine satellite orbits. It provides diagnostic information on the quality of the orbits and the data used in producing those orbits. The basic technique employed is one of weighted least squares whe...

J. W. O'Toole

1976-01-01

230

CELEST computer program for computing satellite orbits  

Microsoft Academic Search

The CELEST Computer Program uses raw Doppler data to determine satellite orbits. It provides diagnostic information on the quality of the orbits and the data used in producing those orbits. The basic technique employed is one of weighted least squares where the data is edited and weighted within the program. An iterative capability exists for nonlinear problems. Trajectories are formed

J. W. Otoole

1976-01-01

231

Quasi-geostationary observations of CO2 from a highly elliptical orbit (HEO): a potential method for monitoring Arctic and Boreal CO2 fluxes (Invited)  

NASA Astrophysics Data System (ADS)

Geostationary satellites have the potential to observe atmospheric CO2 with unprecedented temporal coverage, but these observations are limited to about 60°N-60°S latitude, thus excluding the northernmost Boreal forests and the Arctic. A highly elliptical orbit (HEO) offers the potential for quasi-geostationary observations of these high latitude regions. Canada's proposed Polar Communications and Weather (PCW) mission would consist of two satellites in a HEO configuration, optimized for observing northern high latitudes (~50-90°N). Although the primary mission drivers are Arctic weather and communications, a mission enhancement consisting of an imaging Fourier transform spectrometer (FTS) operating in the thermal infrared (TIR) to near-infrared (NIR) is also under consideration. CO2 and CH4 bands in the 5990-6257 cm-1 region (0.25 cm-1 resolution) and the O2 A band at 13060-13168 cm-1 (0.5 cm-1 resolution) would enable retrieval of XCO2 and XCH4. We report on an observing system simulation experiment (OSSE) to compare the use of XCO2 observations from PCW versus those from GOSAT for constraining Arctic and Boreal CO2 fluxes by inverse modelling. Our results demonstrate that HEO observations would yield improved constraints on regional-scale northern CO2 fluxes, where permafrost and other components of the carbon cycle will be important to monitor over the coming years.

Nassar, R.; Sioris, C. E.; McConnell, J. C.; Jones, D. B.

2013-12-01

232

Space weather radiation effects on geostationary satellite solid-state power amplifiers  

NASA Astrophysics Data System (ADS)

In order to understand and mitigate the effects of space weather on the performance of geostationary (GEO) communications satellites, we analyze 16 years of archived telemetry data from Inmarsat, the UK-based telecommunications company. We compare 665,112 operational hours of housekeeping telemetry from two generations of satellites, designated as Fleet A and Fleet B. Each generation experienced 13 solid-state power amplifier (SSPA) anomalies for a total of 26 anomalies from 1996 to 2012. We compare telemetry from the Inmarsat anomalies with space weather observations, including data from the OMNI2 database, Geostationary Operational Environmental Satellites, the Advanced Composition Explorer Satellite, and Los Alamos National Laboratory (LANL) GEO observations; the evolution of the sunspot number; and the Kp index. Most SSPA anomalies for Fleet A occur as solar activity declines; Fleet B has not yet experienced a full solar cycle. For both fleets, the average value of Kp remained < 2 over time periods of 2 days, 3 days, and 2 weeks around the time of anomaly, which suggests that the anomalies occurred at times of relatively quiet geomagnetic activity and that they were probably not solely caused by surface charging. From 1996 to 2009, the average of the 1.8-3.5 MeV electron flux was 1.98 #/(cm2 s st keV). Five of the 26 anomalies, unfortunately, do not have corresponding science observations (specifically, electron flux data in the LANL data set), so part of this study focuses on the 21 anomalies when science observations were available. Six out of 21 anomalies experienced a high-energy electron flux greater than 1.5 standard deviations above the mean of the log10 of the flux between 7 and 14 days prior to the anomaly. By contrast, a Monte Carlo simulation finds that on average, only 2.8 out of 21 (13%) of randomly assigned "anomalies" occur between 7 and 14 days after an electron flux greater than 1.5 standard deviations above the mean. Our observations suggest that internal charging from either past elevated radiation belt fluxes or some conditions related to relativistic electron enhancements (either causally or accidentally) is most likely responsible for the SSPA anomalies. We next consider the timing of these anomalies with respect to the local time (LT) and season. Anomalies occur at all LT sectors with 46% (Fleet A) and 38.5% (Fleet B) in the midnight to dawn sector and 54% (Fleet A) and 46% (Fleet B) in the local noon to dusk sector. From the local time distribution, surface charging does not appear to be the sole causative agent of the anomalies. Understanding the connection between the space weather conditions and anomalies on subsystems and specific components on identical and similar geostationary communications satellites for periods of time longer than a solar cycle will help guide design improvements and provide insight on their operation during space weather events.

Lohmeyer, W. Q.; Cahoy, K.

2013-08-01

233

Improving the orbits of eclipsing GPS satellites  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

234

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

235

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

NASA Technical Reports Server (NTRS)

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.

Bauer, Robert A.

2000-01-01

236

Orbit synthesis for target satellites  

NASA Astrophysics Data System (ADS)

The purpose of the study is to illustrate the orbit synthesis process for a hypothetical test of a direct-ascent-based kinetic energy weapon (KEW) against an instrumented test vehicle. Test arena and communications considerations for a ground-based directed energy weapon and a direct-ascent-based KEW are outlined, along with launch vehicle constraints, algorithms for off-nominal orbits, and thermal-control and orbit lifetime considerations. Focus is placed on altitude and illumination cycles, general-test and detailed-test constraints, and methodologies for assessing orbit performance. The orbit synthesis is demonstratedd, with emphasis on the test opportunity influence on orbit inclination, test window concept, selection of apogee altitude, orbit inclination, perigee altitude, launch window, and the effect of the launch date.

Wilkinson, Charles K.

237

Improving the orbit estimates of GPS satellites.  

NASA Astrophysics Data System (ADS)

The extended Center for Orbit Determination in Europe (CODE) orbit model, an empirical orbit model proposed by Beutler and colleagues in 1994, has been tested extensively since January 1996. Apart from six osculating Keplerian elements, this orbit model consists of nine (instead of the conventional two) parameters to take into account the deterministic part of the force field acting on the satellites. Based on the test results an improved orbit parameterization is proposed. The new orbit parameterization consists of the conventional two parameters plus three additional parameters, a constant and two periodic terms (a cosine and a sine term), in the X-direction to model the effects of the solar radiation pressure. Results based on one full year of routine orbit estimation, using the original and the new orbit parameterization, are presented to demonstrate the superiority of the new approach. An improvement of the orbit estimates with at least a factor of two is observed.

Springer, T. A.; Beutler, G.; Rothacher, M.

1999-04-01

238

Remote Synchronization Experiments for Future Quasi-Zenith Satellite System Using Current Geostationary Satellites.  

National Technical Information Service (NTIS)

Japan's Quasi-Zenith Satellite System (QZSS) is scheduled for launching in 2010. We have been conducting research on the remote synchronization system for the onboard crystal oscillator (RESSOX), which does not require onboard atomic clocks, for the QZSS ...

M. Fukui M. Imae T. Iwata T. Suzuyama Y. Hashibe

2008-01-01

239

Revised Orbits of Saturn's Small Inner Satellites  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

240

Statistical Analysis of Pitch Angle Distribution of Radiation Belt Energetic Electrons Near the Geostationary Orbit: CRRES Observations  

NASA Astrophysics Data System (ADS)

A statistical analysis of energetic radiation belt electron pitch angle distributions (PADs) at the radial distances of 6 RE and 6.6 RE is performed on the basis of the pitch angle resolved flux observations from the Medium Electrons A (MEA) instrument onboard the Combined Release and Radiation Effects Satellite (CRRES). While previous studies of Vampola [1998] and Gannon et al. [2007] have used CRRES MEA data to investigate the general variations in electron PAD at particular energies, in this study we present a detailed statistical analysis of electron PADs including the dependence on electron kinetic energy, magnetic local time (MLT), and the level of geomagnetic activity. By fitting the measured PADs with a power law function of sine of local pitch angle, the power law index n that relates to the category of radiation belt electron PAD is quantified in detail as a function of electron kinetic energy, MLT interval and geomagnetic index Kp. Statistical averaged n-values vary considerably with respect to MLT, ranging from n ~ 0 within 00-04 MLT to n ~ 1.5 within 12-16 MLT, due to the MLT dependence of wave scattering and the effects associated with drift shell splitting and magnetopause shadowing. Drift shell splitting and magnetopause shadowing result in often observed negative values of n. At lower energies of a few hundred keV the pitch angle distributions are more flat than at MeV energies, which is consistent with faster pitch angle scattering at low energies by chorus waves. These quantitative results of radiation belt electron PAD, consistent with the previous studies by Vampola [1998] and Gannon et al. [2007], provide further insight into the global dynamics of energetic radiation belt electrons near the geostationary orbit and also are useful for inferring electron phase space densities and assimilating their radial profiles using omni-directional electron flux measurements.

Zhao, Z.; Gu, X.; Ni, B.; Shprits, Y.; Zhou, C.; Ionosphere Laboratory of Wuhan University

2011-12-01

241

Statistical analysis of pitch angle distribution of radiation belt energetic electrons near the geostationary orbit: CRRES observations  

NASA Astrophysics Data System (ADS)

A statistical analysis of energetic radiation belt electron pitch angle distributions (PADs) at the radial distances of 6 RE and 6.6 RE is performed on the basis of the pitch angle resolved flux observations from the Medium Electrons A (MEA) instrument onboard the Combined Release and Radiation Effects Satellite (CRRES). While previous studies of Vampola (1998) and Gannon et al. (2007) have used CRRES MEA data to investigate the general variations in electron PAD at particular energies, in this study we present a detailed statistical analysis of electron PADs including the dependence on electron kinetic energy, magnetic local time (MLT), and the level of geomagnetic activity. By fitting the measured PADs with a power law function of sine of local pitch angle, the power law index n that relates to the category of radiation belt electron PAD is quantified in detail as a function of electron kinetic energy, MLT interval, and geomagnetic index Kp. Statistical averaged n values vary considerably with respect to MLT, ranging from n ˜ 0 within 0000-0400 MLT to n ˜ 1.5 within 1200-1600 MLT, because of the MLT dependence of wave scattering and the effects associated with drift shell splitting and magnetopause shadowing. Drift shell splitting and magnetopause shadowing result in often observed negative values of n. At lower energies of a few hundred keV the pitch angle distributions are more flat than at MeV energies, which is consistent with faster pitch angle scattering at low energies by chorus waves. These quantitative results of radiation belt electron PAD, consistent with the previous studies by Vampola (1998) and Gannon et al. (2007), provide further insight into the global dynamics of energetic radiation belt electrons near the geostationary orbit and also are useful for inferring electron phase space densities and assimilating their radial profiles using omnidirectional electron flux measurements.

Gu, Xudong; Zhao, Zhengyu; Ni, Binbin; Shprits, Yuri; Zhou, Chen

2011-01-01

242

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

243

Orbit synthesis for target satellites  

Microsoft Academic Search

The purpose of the study is to illustrate the orbit synthesis process for a hypothetical test of a direct-ascent-based kinetic energy weapon (KEW) against an instrumented test vehicle. Test arena and communications considerations for a ground-based directed energy weapon and a direct-ascent-based KEW are outlined, along with launch vehicle constraints, algorithms for off-nominal orbits, and thermal-control and orbit lifetime considerations.

Charles K. Wilkinson

1990-01-01

244

A simulation for detection of the lower tropospheric ozone from a geostationary satellite  

NASA Astrophysics Data System (ADS)

Accompanying with recent development of industry and economy in Asian countries, emissions of air pollutants have been increasing significantly. Long-range, transboundary transport of these pollutants probably affects the atmospheric environment and the regional climate in this region. In Japan, surface ozone concentration has been gradually increasing and photochemical smog sometimes occurs not only in urban regions but also in remote areas, and one of the causes of this ozone increase is considered to be transboundary transport of polluted air masses in East Asia. Geostationary (GEO) satellite observation of air pollutants, such as ozone, over Asia is expected to contribute to understanding the photochemical and transport processes as well as the spatial and temporal variation of their emissions in this region. However, because a GEO satellite measures solar spectra scattered in the midlatitudes along a very slant path, most of UV light is scattered above the lower troposphere including the planetary boundary layer. Thus, the retrieval of ozone from UV (Huggins bands) scattered spectra is less sensitive to ozone near the surface in this region. On the contrary, the visible (Chappuis bands) light scattered near the surface can be measured from the GEO satellite. Therefore it is possible to retrieve ozone in the lower troposphere from simultaneously measured UV and visible spectra. Simulations of this retrieval were conducted to estimate the precision, and have shown that the ozone concentration below an altitude of 3 km can be estimated with the precision better than 50 percent when ozone mixing ratio is about 100ppbv. Preliminary results of a simulating measurement of UV and visible spectra from a mountain top will be also presented.

Kita, Kazuyuki; Otake, Sho; Nakachi, Masaki; Irie, Hitoshi; Nakazato, Masahisa

245

The Orbits of the Inner Uranian Satellites  

Microsoft Academic Search

We report on the numerically integrated orbits for the thirteen inner Uranian satellites. Our dataset includes Voyager imaging data as well as HST and Earth-based astrometric data. The observations span time period from 1985 to 2003. Our model of the inner moons' orbits accounts for the equatorial bulge of Uranus, the perturbations from the external bodies and the perturbations from

Marina Brozovic; R. A. Jacobson

2009-01-01

246

Methods for predicting satellite orbital lifetimes  

Microsoft Academic Search

The accurate prediction of satellite decay dates some months or years ahead remains one of the most difficult and intractable problems of orbital mechanics, chiefly because the lifetime depends strongly on the future variations in air density, which are at present not accurately predictable. Simple graphical methods are presented for estimating the future lifetime of an earth satellite from its

D. G. King-Hele

1977-01-01

247

Geos-C Orbit Determination with Satellite to Satellite Tracking.  

National Technical Information Service (NTIS)

The feasibility of employing satellite to satellite tracking in lieu of ground based tracking to satisfy the orbit determination requirements of the GEOS-C mission was studied. It is shown that with proper estimation procedures it is possible to obtain fr...

P. Argentiero

1974-01-01

248

Satellite Orbital Interpolation using Tchebychev Polynomials  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

249

Energetic particle injections to geostationary orbit: Relationship to flow bursts and magnetospheric state  

NASA Astrophysics Data System (ADS)

To address the mechanism and factors controlling the injection of energetic particles to the geostationary orbit (GEO), we analyzed the appearance of injections at the GEO drift shell as observed by LANL spacecraft in the cases where the flow bursts and associated transient dipolarization were detected at the entry to the inner magnetosphere, in the high beta plasma sheet region on the nightside between 8 and 13 Re. We analyzed two different data sets, one including Geotail observations in 1995-2005 and another including a set of Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations in 2008-2009. We found that only a small portion of all flow bursts at 8-13 Re were associated with particle injection at GEO but that those injection-associated flows had smaller values of plasma tube entropy parameter (PV5/3) as well as larger change of magnetic field north-south component (dBz). This confirms a scenario that the bursty flows at the entry of the inner magnetosphere (8-13 Re) penetrate into GEO and produce there the energetic particles flux increase. According to the bubble theory of magnetotail plasma flows, the probability of the deep plasma penetration critically depends on how stretched the magnetospheric configuration is, and this dependence is statistically confirmed in a large database to be the major factor controlling the occurrence of GEO injections. We suggest using the background plasma tube entropy value in the nightside part of the GEO drift shell as a suitable parameter to predict the probability of particle injection to GEO. One more outcome of this study is that the energetic particle injections cannot reliably serve as a tool to identify the substorm onset times, as has been done in many past studies.

Sergeev, V. A.; Chernyaev, I. A.; Dubyagin, S. V.; Miyashita, Y.; Angelopoulos, V.; Boakes, P. D.; Nakamura, R.; Henderson, M. G.

2012-10-01

250

ORANGE: Orbital analytical model for geosynchronous satellite  

NASA Astrophysics Data System (ADS)

ORANGE semi-analytical model is an approximate representation of the centered orbital parmeters evolution of a geosynchronous orbit built with the symbolic computation tool MAPLE. The centered orbital parameters from which short term variations are removed and daily average is computed to remove small amplitude variations. The method we have applied consists in expanding the perturbation functions in adapted orbit parameters and incorporating these developments in to the Lagrange equations. All the computations are done with the symbolic computation tool MAPLE which considerably decreases the risk of error and then, also allows us to develop the equation to a higher order. The targeted accuracy is afetr 30 days of extrapolating: 10 meters on the semi-major axis, 10(exp -5) on the eccentricity, 10(exp -3) degrees on the inclination and 10(exp -3) degrees for the mean longitude. This accuracy in a validity domain such as the semi-major axis is closer than 500 km from the geosynchronous one, the eccentricity is lower than 0.01 and the inclination 5 deg, which represents a wide window around a geostationary position.

Campan, Genevieve; Brousse, Pascal

251

Lifetimes of lunar satellite orbits  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

252

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

253

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

NASA Astrophysics Data System (ADS)

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.

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

2007-06-01

254

PREDICT: Satellite tracking and orbital prediction  

NASA Astrophysics Data System (ADS)

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.

Magliacane, John A.

2011-12-01

255

Temporal variation of the cloud top height over the tropical Pacific observed by geostationary satellites  

NASA Astrophysics Data System (ADS)

Stratiform clouds (nimbostratus and cirriform clouds) in the upper troposphere accompanied with cumulonimbus activity cover large part of the tropical region and largely affect the radiation and water vapor budgets there. Recently new satellites (CloudSat and CALIPSO) can give us the information of cloud height and cloud ice amount even over the open ocean. However, their coverage is limited just below the satellite paths; it is difficult to capture the whole shape and to trace the lifecycle of each cloud system by using just these datasets. We made, as a complementary product, a dataset of cloud top height and visible optical thickness with one-hour resolution over the wide region, by using infrared split-window data of the geostationary satellites (AGU fall meeting 2011) and released on the internet (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?m brightness temperature (Tb) and the difference between the 11?m Tb and 12?m Tb. We will call our estimated cloud top height as "CTOP" below. The area of our coverage is 85E-155W (MTSAT2) and 80E-160W(MTSAT1R), and 20S-20N. The accuracy of the estimation with the IR split-window observation is the best in the upper tropospheric height range. We analyzed the formation and maintenance of the cloud systems whose top height is in the upper troposphere with our CTOP analysis, CloudSat 2B-GEOPROF, and GSMaP (Global Satellite Mapping of Precipitation) precipitation data. Most of the upper tropospheric stratiform clouds have their cloud top within 13-15 km range. The cloud top height decreases slowly when dissipating but still has high value to the end. However, we sometimes observe that a little lower cloud top height (6-10 km) is kept within one-two days. A typical example is observed on 5 January 2011 in a dissipating cloud system with 1000-km scale. This cluster located between 0-10N just west of the International Date Line and moved westward with keeping relatively lower cloud top (6-10 km) over one day. This top height is lower than the ubiquitous upper-tropospheric stratiform clouds but higher than the so-called 'congestus cloud' whose top height is around 0C. CloudSat data show the presence of convective rainfall. It suggests that this cloud system continuously kept making new anvil clouds in a little lower height than usual. We examined the seasonal variation of the distribution of cloud systems with a little lower cloud top height (6-11 km) during 2010-11. The number of such cloud systems is not constant with seasons but frequently increased in some specific seasons. Over the equatorial ocean region (east of 150E), they were frequently observed during the northern winter.

Nishi, N.; Hamada, A.

2012-12-01

256

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

257

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

PubMed

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

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

2013-01-01

258

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

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

259

GOCE Satellite Orbit in a Computational Aspect  

NASA Astrophysics Data System (ADS)

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.

Bobojc, Andrzej; Drozyner, Andrzej

2013-04-01

260

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

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

261

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

ERIC Educational Resources Information Center

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

Papay, Kate; And Others

1996-01-01

262

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

NASA Astrophysics Data System (ADS)

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.

Puca, S.; Porcu, F.; Rinollo, A.; Vulpiani, G.; Baguis, P.; Balabanova, S.; Campione, E.; Ertürk, A.; Gabellani, S.; Iwanski, R.; Jurašek, M.; Ka?ák, J.; Kerényi, J.; Koshinchanov, G.; Kozinarova, G.; Krahe, P.; Lapeta, B.; Lábó, E.; Milani, L.; Okon, L'.; Öztopal, A.; Pagliara, P.; Pignone, F.; Rachimow, C.; Rebora, N.; Roulin, E.; Sönmez, 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.; Sanò, P.; Zauli, F.; Rosci, P.; De Leonibus, L.; Agosta, E.; Gattari, F.

2014-04-01

263

THE ORBITS OF NEPTUNE'S OUTER SATELLITES  

SciTech Connect

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.

Brozovic, Marina; Jacobson, Robert A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States); Sheppard, Scott S., E-mail: marina.brozovic@jpl.nasa.gov, E-mail: raj@jpl.nasa.gov, E-mail: sheppard@dtm.ciw.edu [Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road NW, Washington, DC 20015 (United States)

2011-04-15

264

The Orbits of the Inner Uranian Satellites  

NASA Astrophysics Data System (ADS)

We report on the numerically integrated orbits for the thirteen inner Uranian satellites. Our dataset includes Voyager imaging data as well as HST and Earth-based astrometric data. The observations span time period from 1985 to 2003. Our model of the inner moons' orbits accounts for the equatorial bulge of Uranus, the perturbations from the external bodies and the perturbations from the large moons of Uranus (Miranda, Umbriel, Ariel, Oberon, and Titania). The inner satellites were initially considered massless, but we found that this assumption may need to be revised in order to fine-tune the system's dynamics and obtain the orbital solutions with adequate residuals.The results are given in terms of state vectors,post-fit residuals and mean orbital elements.

Brozovic, Marina; Jacobson, R. A.

2009-05-01

265

Verifying the Accuracy of Geostationary Weather Satellite Image Navigation and Registration  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

266

History of on-orbit satellite fragmentations  

NASA Technical Reports Server (NTRS)

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.

Nauer, David J.

1992-01-01

267

History of on-orbit satellite fragmentations  

NASA Astrophysics Data System (ADS)

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.

Nauer, David J.

1992-07-01

268

EROS SYSTEM - SATELLITE ORBIT AND CONSTELLATION DESIGN  

Microsoft Academic Search

The EROS (Earth Resources Observation System) program conducted by ImageSat International N.V. intends to operate a constellation of 8 commercial imaging satellites in LEO (Low Earth Orbit). The first satellite, EROS-A1, was successfully launched by a Russian START-1 launcher on December 5th, 2000, and is presently successfully operating with 1.8 meter to 1.0-meter resolution. This article presents the requirements and

Moshe Bar-Lev; Leonid Shcherbina; Vola Levin

2001-01-01

269

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

NASA Technical Reports Server (NTRS)

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.

Polansky, A. C.

1982-01-01

270

The Orbits of Saturn's Small Satellites  

NASA Astrophysics Data System (ADS)

We report on the orbits of the small, inner Saturnian satellites, either recovered or newly-discovered in recent Cassini imaging observations (excluding Helene, Telesto and Calypso, which will be discussed by another group). Using combined Cassini and Voyager observations, the mean motions of Pan and Atlas have been refined by several orders of magnitude. The Atlas orbit is based on a numerical integration perturbed by all of the massive Saturnian satellites including Prometheus, Pandora, Janus, and Epimetheus. We find that the dominant perturber is Prometheus. Cassini, Voyager, HST, and Earth-based data have been used to refine the orbits of Janus, Epimetheus, Prometheus and Pandora. The orbits of the co-orbitals, Janus and Epimetheus, remain stable; their orbital swap does not occur until Februrary, 2006. The orbits of Prometheus and Pandora remain close to recent values (Jacobson and French 2004, Icarus, 172, 382). Six new objects have been discovered to date -- three (S/2004 S3, S4, S6) in close proximity to the F ring, two (S/2004 S1(Methone), S/2004 S2(Pallene)) between the orbits of Mimas and Enceladus, and one (S/2004 S5(Polydeuces)) co-orbital with Dione, trailing by ˜60 deg (Porco et al., Science 307, 25 Feb 2005). One of the F-ring objects -- S/2004 S3 -- was seen over a 118-day interval, but none of those objects, including S/2004 S3, were subsequently recovered in an F-ring movie acquired on 15 November 2004 (29 days after the last sighting of S/2004 S3) with an image scale of 4 km/pixel, in which all were expected to appear. Consequently, we are confident only that Methone, Pallene and Polydeuces are solid satellites; S/2004 S3, S4 and S6 may be transient clumps. Our orbital fits, both precessing ellipse models and orbital integrations, suggest that Pallene is the same object as S/1981 S14, imaged by Voyager 2 on 23 August 1981, contrary to our initial reports (IAU circular 8389). The orbital inclination and eccentricity of Methone are considerably less excited than expected, given its proximity to Mimas (Porco et al., Science; in press), but orbital integrations spanning 4 years show that significant longitudinal perturbations from Mimas explain the observations. Polydeuces' orbit has been integrated over 5 years and is seen to librate about Saturn's L5 point with a period of about 792 days and an amplitude of about 25.8 deg.

Spitale, J. N.; Jacobson, R. A.; Porco, C. C.; Owen, W. M.; Charnoz, S.

2005-05-01

271

Dual RF Astrodynamic GPS Orbital Navigator Satellite  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

272

Online Visualization and Analysis of Merged Global Geostationary Satellite Infrared Dataset  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

273

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

274

On Reduced Dynamic Orbits for Altimetric Satellites  

NASA Astrophysics Data System (ADS)

Precise radial positioning is a prerequisite for satellite altimetry. Orbital precision has improved with enhancements in gravity field modelling to the extent that surface forces are now becoming the major source of error. To overcome deficiencies in the force models the dynamic approach can be relaxed by estimation of a large number of empirical parameters. This so-called reduced dynamic approach is dependent on availability of either dense global tracking from systems such as DORIS or on the use of dual satellite crossovers to link the less precise altimetric mission with a more precise orbit. In this study we detail the reduced dynamic approach introduced within the Newcastle orbital software FAUST and compare and contrast results from the dynamic and reduced dynamic methodologies in terms of tracking residuals, overlaps and crossover residuals for ENVISAT, Jason-1 and GFO.

Moore, P.; Wang, J.

275

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)

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

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

2009-04-01

276

Visible infrared spin-scan radiometers (VISSR) for the Geostationary Operational Environmental Satellite (GOES) B and C application  

NASA Technical Reports Server (NTRS)

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.

1977-01-01

277

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

NASA Astrophysics Data System (ADS)

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.

Chaudhary, Kalpana; Vishvakarma, Babau R.

2010-11-01

278

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

NASA Technical Reports Server (NTRS)

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.

Menzel, Paul; Prins, Elaine

1995-01-01

279

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

NASA Technical Reports Server (NTRS)

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.

Reinhart, E. E.

1974-01-01

280

Application of quaternions to artificial satellite orbital motion. II  

Microsoft Academic Search

Geometrical aspects of the application of quaternions to artificial satellite orbital theory are discussed, equations for perturbed orbit orientations in terms of quaternion osculating elements are introduced, and quaternion equations for satellite motion in the Earth's gravitational field are presented.

Yu. N. Chelnokov

1993-01-01

281

Nodding feed antenna for communications with satellites in synchronous orbit  

NASA Technical Reports Server (NTRS)

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.

Smetana, J.; Zavesky, R.

1978-01-01

282

A feasibility study for the detection of the diurnal variation of tropospheric NO 2 over Tokyo from a geostationary orbit  

NASA Astrophysics Data System (ADS)

We have conducted a feasibility study for the geostationary monitoring of the diurnal variation of tropospheric NO 2 over Tokyo. Using NO 2 fields from a chemical transport model, synthetic spectra were created by a radiative transfer model, SCIATRAN, for summer and winter cases. We then performed a Differential Optical Absorption Spectroscopy (DOAS) analysis to retrieve NO 2 slant column densities (SCDs), and after converting SCDs into vertical column densities (VCDs), we estimated the precision of the retrieved VCDs. The simulation showed that signal-to-noise ratio (SNR) ? 500 is needed to detect the diurnal variation and that SNR ? 1000 is needed to observe the local minimum occurring in the early afternoon (LT13-14) in summer. In winter, the detection of the diurnal variation during LT08-15 needs SNR ? 500, and SNR ? 1000 is needed if early morning (LT07) and early evening (LT16) are included. The currently discussed sensor specification for the Japanese geostationary satellite project, GMAP-Asia, which has a horizontal resolution of 10 km and a temporal resolution of 1hr, has demonstrated the performance of a precision of several percent, which is approximately corresponding to SNR = 1000-2000 during daytime and SNR ? 500 in the morning and evening. We also discuss possible biases caused by the temperature dependence of the absorption cross section utilized in the DOAS retrieval, and the effect of uncertainties of surface albedo and clouds on the estimation of precisions.

Noguchi, Katsuyuki; Richter, Andreas; Bovensmann, Heinrich; Hilboll, Andreas; Burrows, John P.; Irie, Hitoshi; Hayashida, Sachiko; Morino, Yu

2011-11-01

283

Application of quaternions in the theory of satellite orbiting motion  

Microsoft Academic Search

A method for solving satellite orbiting motion problems is developed. The method is based on a quaternion altitude description of a satellite osculating orbit and on Hamilton's quaternion formalism. The first part of this paper considers the quaternion equations of the satellite disturbed orbiting motion in normal and oscillatory forms. In the second part, geometric aspects of the application of

Yu. N. Chelnokov

1992-01-01

284

On reduced dynamic orbits for altimetric satellites  

NASA Astrophysics Data System (ADS)

Precise radial positioning as required for satellite altimetry has improved with enhancements in gravity field modelling to the extent that surface forces are now becoming the major source of error. To overcome deficiencies in the surface force models the adherence to the dynamic approach can be relaxed by estimation of a large number of empirical parameters. This so-called reduced dynamic approach is dependent on availability of either dense global tracking from systems such as DORIS or on the use of dual satellite crossovers to link the less precise altimetric mission with a more precise orbit. In this study we utilise the reduced dynamic approach introduced within the Newcastle orbital software, Faust, and compare and contrast results from the dynamic and reduced dynamic methodologies in terms of tracking residuals, overlaps and crossover residuals for ENVISAT and GFO.

Moore, P.; Wang, J.

285

GPS based onboard and onground orbit operations for small satellites  

Microsoft Academic Search

In extension to common applications such as groundtrack displays and antenna steering, the SGP4 orbit model is proposed for operational orbit determination in small satellite missions. SGP4 is an analytical orbit model for Low-Earth orbiting satellites that is widely used for the propagation of NORAD twoline elements. Twoline elements may hence be generated completely independent of NORAD. Their use as

E. F. Jochim; E. Gill; O. Montenbruck; M. Kirschner

1996-01-01

286

Satellite orbits guidance using state space neural network  

Microsoft Academic Search

This paper develops a state-space neural network (SSNN) to predict the satellite thruster force and control osculating orbital elements during maneuvers. An adequate mathematical satellite model is implemented to simulate the satellite orbit trajectory. When using SSNN for control, the system identification adaptive neural network (ANN) model is implemented to represent the forward dynamics of the satellite. The prediction error

Mohamed A. Zayan

2006-01-01

287

In orbit manufacture of solar reflector satellites  

NASA Technical Reports Server (NTRS)

The implementation of an idea reported by Oberth (1929) is discussed. This idea is concerned with the reflection of sunlight to the ground by means of orbiting metal mirrors. The approach used for implementing Oberth's idea makes use of aluminized Mylar as a reflecting material which is supported with the aid of a structure which includes six booms and a peripheral mirror cable. Four low resistance one turn coils are formed by the structure. Magnetic forces for attitude maneuvers are obtained by energizing the coils. A bipropellant propulsion system is to be used to raise the initial 330 km circular parking orbit to a 330 by 1000 km elliptic orbit. Two thrusters are employed. They are oriented parallel to each other and the mirror surface. The mirror satellite can be completely folded so as to maximize the launch capability of the Shuttle.

Muller, R. M.

1978-01-01

288

Development of precipitation retrievals at millimeter and sub-millimeter wavelengths for geostationary satellites  

Microsoft Academic Search

We study the potential of millimeter and sub-millimeter wavelengths for precipitation retrieval from geostationary sensors based on mesoscale cloud modeling and radiative transfer computation. Hydrometeor profiles simulated with the Meso-NH cloud resolving model for five European midlatitude situations are used to compute the brightness temperatures at frequencies from 23.8 to 875 GHz with the Atmospheric Transmission at Microwaves (ATM). Performances

E. Defer; C. Prigent; F. Aires; J. R. Pardo; C. J. Walden; O.-Z. Zanifé; J.-P. Chaboureau; J.-P. Pinty

2008-01-01

289

A simple analytic method for satellite orbit anomalies  

NASA Astrophysics Data System (ADS)

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

Song, Weidong; Wang, Ronglan

290

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)

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.

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

291

An OSSE to Determine the Impact of Geostationary Satellite Aerosol Optical Depth Observations on Air Quality Forecasts in Europe  

NASA Astrophysics Data System (ADS)

With the availability of a growing number of satellite instruments providing information on atmospheric composition and aerosols, the use of satellite data for air quality applications is becoming a popular subject. Within this context the need for frequent observations of AOD from either geostationary satellites or satellites with multiple overpasses a day is often expressed. The objective of this study is to test the impact of Aerosol Optical Depth (AOD) observations from geostationary satellites on air quality forecasts. To this end several Observing System Simulation Experiments (OSSE's) were performed. The main objective of these experiments was to test the hypothesis that air quality forecasts benefit from frequent observations of AOD. OSSE's are commonly used to quantify the impact of meteorological observations from future observation systems such as satellite instruments or groundbased networks on e.g. weather forecasts. In this study OSSE's are applied to total column AOD measurements from the Flexible Combined Imager (FCI) and vertical AOD profiles from an Oxygen A-band sounder using the LOTOS-EUROS chemistry transport model and the ensemble Kalman filter data assimilation method. Experiments were the AOD observations were sampled at four hour resolution were compared to results obtained when the AOD observations were sampled every half-hour. Experiments suggest that the performance depends critically on the error in the observations, which for the FCI instrument has a strong diurnal variation and large values in the middle of the day. Large errors cause the assimilation system to stay closer to the modelled values than to the observed values. Although in some cases the impact is clearly visible, on average the level of improvement when assimilating total AOD columns from the FCI instrument is small. Obviously the level of improvement also depends on the vicinity of simultaneously assimilated groundbased measurements. In the next step experiments were AOD profile observations from an Oxygen A-band sounder are assimilated will be compared to the results using the FCI total column AOD observations. The impact of the AOD profile measurements is expected to be larger because of lower errors and the vertical information (which is an advantage in case of dust or fires, i.e. high altitude aerosols). But the coarser horizontal resolution of the sounder might give a lower impact in broken cloud cases, when the FCI with its finer horizontal resolution can look in between the clouds.

Timmermans, R.; Builtjes, P.; Tjemkes, S.; Segers, A.; Schaap, M.; Siddans, R.; Vautard, R.; Elbern, H.

2008-05-01

292

Orbital evolution of the main Uranian satellites  

NASA Astrophysics Data System (ADS)

Since Voyager 2 space mission, we know some properties of the main Uranian satellites (Miranda, Ariel, Umbriel, Titania, Oberon): on the one hand, we observe an important resurfacing of both Miranda and Ariel, and on the other hand some strangenesses in the orbital elements such as the anomalously high inclinaison of Miranda or the anomalously high eccentricity of Ariel. The aim of this study is to use some modern methods including advances in computing resources to revise some studies developed in the last 20 years (see for instance [1], [2], [3], [4]). We therefore consider a model of a n-body problem which takes into account of the mutual perturbations of the five main satellites and of the planet Uranus and meet/improve some previous results.

Verheylewegen, E.; Noyelles, B.

2011-10-01

293

Satellite orbit-motion theories and their applications. I  

Microsoft Academic Search

This paper is a short review of the orbital theories of artificial satellites. The dynamical models and the criterion of choosing perturbation terms are given. Various solutions of the equations of motion and some related results of a qualitative analysis for satellite orbits have been discussed. In order to improve the accuracy of the orbital determination, some problems remained to

L. Liu; W. Zhu; C. Huang

1988-01-01

294

Handover management in Low Earth Orbit (LEO) satellite networks  

Microsoft Academic Search

Low Earth Orbit (LEO) satellite networks will play an important role in the evolving information infrastructure. Satellites in the low earth orbits provide communication with shorter end-to-end delays and efficient frequency usage. However, some problems need to be solved before LEO satellite systems can be successfully deployed. One of these problems is the handover management. The objective of this paper

Ian F. Akyildiz; Hüseyin Uzunalio?lu; Michael D. Bender

1999-01-01

295

Low-Earth-orbit satellite systems in ocean science  

Microsoft Academic Search

Scientists and engineers constantly face the challenge of getting data from remote areas of the world's oceans back to their laboratories. Low-Earth-orbit (LEO) satellites already provide routine access to such data. We review the LEO satellite telemetry systems used in ocean sciences. The comparison of available and planned systems includes system design, satellite orbits, data. We review the LEO geographic

P. C. Griffith; D. C. Potts; S. L. Morgan

1996-01-01

296

Communications satellites - Orbiting into the '90s  

NASA Astrophysics Data System (ADS)

Engineering advances in satellite communications are discussed, including sophisticated switchboards, narrow beams, source coding for higher-capacity networks, and the use of higher- and lower-frequency bands and lower orbits. One of the most popular new 14/11-14/12-GHz commercial services has been time-division multiplexing of multiple carriers operating at low to medium bit rates. Multiple-carrier, low-burst-rate TDMA is widely used with VSATs on the customer's premises. NASA's ACTS and Italy's Italsat both plan to use signal regeneration at 30/20 GHz. Onboard switching and multiplexing minimize noise, boost power, but also trim the cost of the entire satellite network. Phone calls and voiceband data are now often carried over satellite circuits and by cable beneath the ocean by adaptive differential pulse-coded modulation (ADPCM). When this technique at 32 kb/s is combined with digital speech interpolation, circuits can carry 4-5 times as many channels as with conventional 64-kb/s pulse-coded transmission.

Campanella, S. Joseph

1990-08-01

297

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

NASA Astrophysics Data System (ADS)

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

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

298

Performance Analysis of the IRIDIUM Low Earth Orbit Satellite System.  

National Technical Information Service (NTIS)

This thesis provides a performance evaluation of the IRIDIUM Low Earth Orbit Satellite system. It examine's the system's ability to meet real time communications constraints with a degraded satellite constellation. The analysis is conducted via computer s...

C. E. Fossa

1998-01-01

299

A feasibility study for the monitoring of diurnal variations of the tropospheric NO2 over Tokyo from a geostationary satellite  

NASA Astrophysics Data System (ADS)

We have conducted a feasibility study for the monitoring of diurnal variations of anthropogenic nitrogen dioxide (NO2) in the lower troposphere over Tokyo, Japan, assuming a geostationary satellite's measurement. First we simulated Earth's atmospheric spectra by using a radiative transfer model, SCIATRAN, in the visible wavelength domain. In the simulation, we implemented the diurnal variations of the vertical profiles of NO2 for summer and winter based on results from the CMAQ model. Using the synthesized spectra, we performed a Differential Optical Absorption Spectroscopy (DOAS) analysis to retrieve NO2 slant column densities (SCDs) and also estimated the precision of the retrieved SCDs. Before the DOAS analysis, we added pseudo-noise components to the synthesized spectra to take into account sensor specification as currently discussed for geostationary instruments. The retrieval simulation showed that the total NO2 SCD (4.0-6.0×1016 molecules/cm2, depending on local time and season) could be measured with the precision of 20% at signal-to-noise ratio (SNR) =~100 and 2% at SNR=~1000, respectively. In our estimation, the precision of SCD did not much depend on local time (LT05-18 in summer and LT07-16 in winter) or season (summer and winter). We found that the diurnal variation of total NO2 SCD from the morning to the evening (about 2.0×1016 molecules/cm2) could be well detected by the sensor with SNR>100. We also discuss the effect of uncertainties in surface reflectivity on the retrieval.

Noguchi, Katsuyuki; Richter, Andreas; Hilboll, Andreas; Burrows, John; Irie, Hitoshi; Hayashida, Sachiko; Morino, Yu

2010-05-01

300

Interference experiment for a SIRIO link in a crowded geostationary orbit environment  

NASA Astrophysics Data System (ADS)

An interference experiment involving the Italian SIRIO and the European OTS satellites is described. The behavior of the SIRIO downlink in the presence of in-band interference is examined in detail. Finally a computer simulation of the up-down differentially encoded binary phase shift keying (DEBPSK) satellite link in the presence of white Gaussian noise, in-band interference, and on-board TWTA nonlinearities is recounted. The simulation made use of the semianalytical method for error probability evaluation. Simulation results are in good agreement with the experimental data.

Lombardi, P.; Marchetti, P. G.; Migliorini, P.; Piazza, F.; Saggese, E.

301

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

NASA Technical Reports Server (NTRS)

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.

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

302

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

303

Geostationary Weather Satellites: Design Progress Made, But Schedule Uncertainty Needs to Be Addressed.  

National Technical Information Service (NTIS)

The GOES-R series is a set of four satellites intended to replace existing weather satellites that will likely reach the end of their useful lives in about 2015. NOAA estimates the series to cost $10.9 billion through 2036. Because the transition to the s...

2012-01-01

304

Circumnutations of sunflower hypocotyls in satellite orbit  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

305

Satellite orbit and data sampling requirements  

NASA Technical Reports Server (NTRS)

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.

Rossow, William

1993-01-01

306

Sentinels in the Sky: Weather Satellites.  

ERIC Educational Resources Information Center

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…

Haynes, Robert

307

ORBITAL DEPENDENCE OF GALAXY PROPERTIES IN SATELLITE SYSTEMS OF GALAXIES  

SciTech Connect

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.

Hwang, Ho Seong; Park, Changbom, E-mail: hoseong.hwang@cea.f, E-mail: cbp@kias.re.k [School of Physics, Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of)

2010-09-01

308

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)

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

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

309

GPS early-orbit subsystem for earth satellites  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

310

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)

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.

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

2013-01-01

311

Traffic management techniques to face the effects of intrinsic delays in geostationary satellite networks  

Microsoft Academic Search

A new scheme for the management of real-time traffic over high-latency broadband satellite networks is described. Early studies on this topic have been reported by Iera, Molinaro and Marano (see IEEE J. Select Areas Commun.,, vol.18, p.2393-2403, 2000), with reference to an integrated terrestrial-satellite platform. In this paper, further enhancement is introduced into the traffic management scheme with a view

Antonio Iera; Antonella Molinaro; Salvatore Marano

2002-01-01

312

Orbit modelling for satellites using the NASA prediction bulletins  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

313

Effect on total system capacity due to imperfect power control for band sharing between CDMA based non-geostationary satellite-PCNs  

Microsoft Academic Search

The demand for global telephony services for mobile users requires the use of constellations of non-geostationary orbits. The proposed S-PCNs are Iridium, Inmarsat-P, Globalstar, Odyssey and Ellipso. The first two systems propose to use a time division multiple access (TDMA) scheme and the others code division multiple access (CDMA) scheme. It is claimed that CDMA based S-PCNs can share the

H. M. Aziz; R. Tafazolli; B. G. Evans

1996-01-01

314

A standard library for modeling satellite orbits on a microcomputer  

NASA Astrophysics Data System (ADS)

Introductory students of astrodynamics and the space environment are required to have a fundamental understanding of the kinematic behavior of satellite orbits. This thesis develops a standard library that contains the basic formulas for modeling earth orbiting satellites. This library is used as a basis for implementing a satellite motion simulator that can be used to demonstrate orbital phenomena in the classroom. Surveyed are the equations of orbital elements, coordinate systems and analytic formulas, which are made into a standard method for modeling earth orbiting satellites. The standard library is written in the C programming language and is designed to be highly portable between a variety of computer environments. The simulation draws heavily on the standards established by the library to produce a graphics-based orbit simulation program written for the Apple Macintosh computer. The simulation demonstrates the utility of the standard library functions but, because of its extensive use of the Macintosh user interface, is not portable to other operating systems.

Beutel, Kenneth L.

1988-03-01

315

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

NASA Astrophysics Data System (ADS)

Between the years 2004 and 2005 the launch of the first gradiometric satellite is planned. This satellite will be an important element of the Gravity Field and Steady - State Ocean Circulation Explorer Mission (GOCE). This mission is one of the reasons for performing the simulation research of the Satellite Gravity Gradiometry. Our work contains the theory description and simulation results of the satellite orbit determination using the gravity tensor observations. In the process of the satellite orbit determination the initial dynamic state vector corrections are obtained. These corrections are estimated by means of the gravity gradiometry measurements. The performed simulations confirm the possibility of satellite orbit determination by means of the gravity tensor observations.Key words. satellite geodesy, satellite gradiometry, satellite orbits

Boboj?, A.; Dro?yner, A.

2003-06-01

316

Real-Time Environment Monitoring Using Data from METEOSAT and NOAA Imaging Satellites,  

National Technical Information Service (NTIS)

An operational remote sensing system is described which supports the environment monitoring using the multi sensor-multi temporal data acquired by the geostationary and polar orbiting weather satellites. The information derived from the satellite images a...

H. A. van Ingen Schenau J. C. Venema

1987-01-01

317

Satellite Meteorology: Online Remote Sensing Guide  

NSDL National Science Digital Library

This guide presents introductory information about satellites and remote sensing and their uses in meteorological observations and forecasting. Topics include geostationary and polar orbiting satellites, orbital coverage, architecture, instruments, and the types of data they produce. A tutorial on interpreting satellite images is also included.

318

Why no orbital resonances among the satellites of Uranus?  

NASA Technical Reports Server (NTRS)

Most of the orbital resonances among the satellites of the major planets are thought to be assembled by differential tidal expansion of their orbits. Why this has not occurred for the Uranus system can be investigated by determining the resonances which would be encountered for various values of Uranus' tidal effective Q. The comparison and the possible escape of Ariel-Umbriel from the 5:3 resonance mean that it is not unreasonable that no orbital resonances are found among these satellites.

Peale, S. J.

1987-01-01

319

Geostationary satellites launched by NASA. Part 1: NASDA tracking and control system  

NASA Astrophysics Data System (ADS)

Software used by the National Space Development Agency (NASDA) of Japan is described. The telemetry and command processing (on-line) and housekeeping data processing; orbit determination, including tracking data preprocessing and orbital event prediction; attitude determination, including telemetry data preprocessing and sensor event prediction; maneuver planning and command generation, including apogee kick motor firing, station acquisition and keeping, and command evaluation and the mission analysis subsystems are discussed. The system operates on-line during the launch phase and off-line during the stationary phase. The system has proven reliable for all NASDA missions.

Takenouchi, T.; Suzuki, M.

1981-08-01

320

Discovery of 12 satellites of Saturn exhibiting orbital clustering.  

PubMed

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

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

321

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

322

Development of an Objective Scheme to Estimate Tropical Cyclone Intensity from Digital Geostationary Satellite Infrared Imagery  

Microsoft Academic Search

The standard method for estimating the intensity of tropical cyclones is based on satellite observations (Dvorak technique) and is utilized operationally by tropical analysis centers around the world. The technique relies on image pattern recognition along with analyst interpretation of empirically based rules regarding the vigor and organization of convection surrounding the storm center. While this method performs well enough

Christopher S. Velden; Timothy L. Olander; Raymond M. Zehr

1998-01-01

323

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

324

Orbit determination accuracies using satellite-to-satellite tracking  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

325

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

NASA Technical Reports Server (NTRS)

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.

Pritchard, E. I.

1977-01-01

326

Intercomparisons of ground-based and satellite-based lightning measurements used in creating a proxy dataset for the Geostationary Lightning Mapper  

NASA Astrophysics Data System (ADS)

We have been comparing several ground-based lightning RF sensing networks (LMA, WTLN, WWLLN) with the satellite-based, optical sensing Lightning Imaging Sensor (LIS). The desire is to create a realistic proxy dataset for the upcoming Geostationary Lightning Mapper (GLM), also an optical sensor. The LIS data are the closest approximation that we have for GLM data, but since it is a Low-Earth Orbiting (LEO) sensor, any spot on the ground is observed for no more than 80 s. The goal is to be able to use any ground-based sensing network, which are typically operated 24x7, and build a transfer function that will allow us to generate proxy GLM pixels. This process is complicated because ground networks are RF sensors and the LIS is an optical sensor. This means that (1) they are sensing different physics during the flash, and (2) the cloud does not scatter RF, but is a very effective light scatterer. The North Alabama Lightning Mapper Array (NALMA) is a VHF sensing network and in a comparison with LIS over many years but limited space (about 150 km from Huntsville, AL), we find a coincidence rate of 70-80%. The WTLN senses a range of the spectrum from VLF to HF; a comparison with LIS of a few months of data that ranges across the Western Hemisphere, we find a coincidence rate of 50-70%. The WWLLN network senses VLF radiation and a comparison with LIS of one month of data also covering the Western Hemisphere, we find a coincidence rate of 7-15%. We will show how a transfer function is derived and give details about how GLM proxy data are generated.

Bateman, M. G.; Thompson, K. B.; Mach, D. M.; Goodman, S. J.; Heckman, S.; Holzworth, R. H.; Koshak, W. J.; Blakeslee, R.

2011-12-01

327

Estimating on-orbit optical properties for GNSS satellites  

NASA Astrophysics Data System (ADS)

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.

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

328

A Tool and Application Programming Interface for Browsing Historical Geostationary Satellite Data  

NASA Astrophysics Data System (ADS)

Providing access to information is a key concern for NASA Langley Research Center. We describe a tool and method that allows end users to easily browse and access information that is otherwise difficult to acquire and manipulate. The tool described has as its core the application-programming interface that is made available to the public. One goal of the tool is to provide a demonstration to end users so that they can use the enhanced imagery as an input into their own work flows. This project builds upon NASA Langley Cloud and Radiation Group's experience with making real-time and historical satellite imagery accessible and easily searchable. As we see the increasing use of virtual supply chains that provide additional value at each link there is value in making satellite imagery available through a simple access method as well as allowing users to browse and view that imagery as they need rather than in a manner most convenient for the data provider.

Chee, T.; Nguyen, L.; Minnis, P.; Spangenberg, D.; Ayers, J.

2013-12-01

329

The Relationship of Satellite Anomalies and Launch Failures to the Space Weather  

Microsoft Academic Search

A statistical evaluation of the impact of space weather on space missions has been made using a large database of geostationary and low-Earth orbit satellite anomalies. The database covers the period 1971-94, comprising the growth, maximum, and decline phases of solar activity. During solar maximum, solar protons are the main cause of geostationary satellite anomalies, whereas during the growth, and

Viacheslav Pilipenko; Nataly Romanova; Norma Bock Crosby

2008-01-01

330

Investigation of cloud/water vapor motion winds from geostationary satellite  

NASA Technical Reports Server (NTRS)

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.

1993-01-01

331

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

332

Method of resolving radio phase ambiguity in satellite orbit determination  

NASA Technical Reports Server (NTRS)

For satellite orbit determination, the most accurate observable available today is microwave radio phase, which can be differenced between observing stations and between satellites to cancel both transmitter- and receiver-related errors. For maximum accuracy, the integer cycle ambiguities of the doubly differenced observations must be resolved. To perform this ambiguity resolution, a bootstrapping strategy is proposed. This strategy requires the tracking stations to have a wide ranging progression of spacings. By conventional 'integrated Doppler' processing of the observations from the most widely spaced stations, the orbits are determined well enough to permit resolution of the ambiguities for the most closely spaced stations. The resolution of these ambiguities reduces the uncertainty of the orbit determination enough to enable ambiguity resolution for more widely spaced stations, which further reduces the orbital uncertainty. In a test of this strategy with six tracking stations, both the formal and the true errors of determining Global Positioning System satellite orbits were reduced by a factor of 2.

Councelman, Charles C., III; Abbot, Richard I.

1989-01-01

333

Electric Propulsion for Low Earth Orbit Communication Satellites  

NASA Technical Reports Server (NTRS)

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.

Oleson, Steven R.

1997-01-01

334

The National Polar-orbiting Operational Environmental Satellite System  

Microsoft Academic Search

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

H. Bloom

2004-01-01

335

Collocation of two GEO satellites and one inclined GSO satellite  

Microsoft Academic Search

Three collocation strategies are planned and analyzed for the cluster of two geostationary orbit (GEO) satellites and one inclined geosynchronous orbit (GSO) satellite in the same longitude control band of 116°E±0.05° . The longitudinal control bands are allocated for the two GEO satellites and one inclined GSO satellite with seven-day East\\/West station-keeping maneuver cycle. The latitudinal control bands are allocated

Byoung-Sun Lee; Kyu-Hong Choi

2000-01-01

336

Aerosol impact on the Earth radiation budget-a study in support of the Geostationary Earth Radiation Budget experiment  

Microsoft Academic Search

Preliminary to the launch of the first Meteosat Second Generation satellite (MSG) and within support of the Geostationary Earth Radiation (GERB) instrument onboard MSG, algorithms are tested to detect aerosol optical parameters and their possible signature on the Earth Radiation Budget (ERB) using existing data from instruments on satellites in low Earth orbit like NOAA\\/AVHRR and ScaRaB

K. Dammann; R. Hollmann; J. Mueller; R. Stuhlmann

1999-01-01

337

Aerosol impact on the Earth radiation budget in support of the Geostationary Earth Radiation Budget (GERB) experiment  

Microsoft Academic Search

Preliminary to the launch of the first Meteosat Second Generation (MSG) satellite and within support of the Geostationary Earth Radiation Budget experiment onboard of MSG, algorithms are tested to retrieve aerosol optical parameters and their possible signature on the Earth Radiation Budget (ERB). For this existing data from instruments on satellites in low earth orbit is used like NOAA\\/AVHRR and

Knut W. Dammann; Rainer Hollmann; Rolf Stuhlmann

2001-01-01

338

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

NASA Technical Reports Server (NTRS)

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.

1991-01-01

339

Orbit determination for low Earth orbit spacecraft based on satellite to satellite tracking techniques via a unique very high altitude relay constellation  

Microsoft Academic Search

This study applies the work of John E. Draim in looking at an unique high altitude satellite constellation of elliptical orbits, which provides continuous global coverage, and considers the mission application of satellite to satellite tracking for this four satellite constellation. Such an application could provide precise, timely and affordable orbit determination services to a variety of low Earth orbit

Douglas Roger Tighe

1986-01-01

340

CBERS Satellites: Resonant Orbital Motions in LEO Region  

NASA Astrophysics Data System (ADS)

Abstract (2,250 Maximum Characters): The space between the Earth and the Moon has several artificial satellites and space debris in some resonance. Synchronous satellites in circular or elliptical orbits have been studied in literature, including the analysis of resonant orbits characterizing the dynamics of these satellites. In general, some resonant angles associated to the exact resonance are considered in the numerical integration, with the purpose to describe the resonance defined by the commensurability between the mean motion of the object and the Earth’s rotation angular velocity. However, the tesseral harmonics Jlm produce multiple resonances in the exact resonance and in the neighborhood of the exact resonance, and, some disturbances in the orbital motions of objects are not described. In this work, the TLE (Two-Line Elements) of the NORAD (North American Defense) are studied observing the resonant objects orbiting the Earth in LEO (Low Earth Orbit) region. Analyzing the cataloged objects, the CBERS satellites are studied observing resonance effects which compose your orbits. The time behavior of the orbital elements, resonant period and resonant angles are considered and possible regular and irregular motions are analyzed. About 60 space debris produced by the CBERS-1 satellite mission are studied analyzing the reentry of these objects in the Planet.

Vilhena de Moraes, Rodolpho; Sampaio, J. C.; da Silva Fernandes, S.; Wnuk, E.

2013-05-01

341

Satellite telemetry  

NASA Astrophysics Data System (ADS)

Hydrologic application of satellite data collection systems in Brazil is discussed. The Data Collection Platform (DCP) is a telemetry station used for the acquisition of environmental parameters. Artificial satellites are employed to relay the data to receiving centers. Two meteorologic satellite data collection systems are in operation in Brazil: the ARGOS system, on board low-orbit (850 km) satellites of the TIROS-NOAA series, and the Geostationary Operational Satellite (GOES) system, on board geostationary satellites (36,000 km) of the SMS/GOES series. DCPs have been used mainly in the field of hydrology to obtain timely data, to make decisions, and to compose historical records. The first DCP network established in Brazil was in the Tocantins Basin, which has 10 telemetry stations. Other networks are currently being planned. Prototypes of ARGOS and GOES DCPs are being developed that are aimed at further industrialization and improved supply of national demand.

Deolveira, J. R.

1983-08-01

342

Observations of orbital debris and satellites in Slovak Republic  

Microsoft Academic Search

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

Jiri Silha; Juraj Toth

2010-01-01

343

Modelling and control of orbit relative motion in small satellites  

Microsoft Academic Search

This work develops a multi-input multi-output robust controller to compensate the effects of atmospheric drag perturbations in the orbit tracking to be performed by small low altitude satellites. In particular, it is shown an approach for computing a H? controller for the singular case when orbit dynamics are formulated through a relative motion model The problem captures some features related

David Prieto; Basilio Bona

2004-01-01

344

Verification of KAM Theory on Earth Orbiting Satellites.  

National Technical Information Service (NTIS)

This paper uses KAM torus theory and Simplified General Perturbations 4 (SGP4) orbit prediction techniques compiled by Dr. William Wiesel and compares it to Analytical Graphics Incorporated (AGI)Satellite Toolkit (STK) orbit data. The goal of this paper i...

C. L. Bisher

2010-01-01

345

Method of resolving radio phase ambiguity in satellite orbit determination  

Microsoft Academic Search

For satellite orbit determination, the most accurate observable available today is microwave radio phase, which can be differenced between observing stations and between satellites to cancel both transmitter- and receiver-related errors. For maximum accuracy, the integer cycle ambiguities of the doubly differenced observations must be resolved. To perform this ambiguity resolution, a bootstrapping strategy is proposed. This strategy requires the

Charles C. Councelman III; Richard I. Abbot

1989-01-01

346

Secular love and tidal numbers of synchronously orbiting satellites  

Microsoft Academic Search

The secular Love and the secular tidal numbers have been computed for eight synchronously orbiting satellites in the solar system for which the triaxiality parameters and satellite-centric gravitational constant are available. Excepting Deimos the total mass of which should be first refined, the secular Love and tidal numbers are rather close to unity, as a rule. That is why, the

M. Bursa

1988-01-01

347

In-Orbit Storage of NOAA-NESS Standby Satellites.  

National Technical Information Service (NTIS)

This paper presents an operational proposal for the orderly storage, in-orbit, of NOAA-NESS satellites that are in some degree of Standby condition. This scheme would reduce to a reasonable minimum the monitoring of these satellites by the NESS ground sys...

B. Sharts C. Dunker

1977-01-01

348

The Geostationary Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

349

The Geostationary Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

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.

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

350

On the decay of satellite orbits  

Microsoft Academic Search

The prediction of the decay time of a satellite is difficult since it depends essentially on the variations of the density in the lower thermosphere which are due to solar and geomagnetic activity during the remaining lifetime of the satellite. The uncertainty induced by the density variations correlated with solar and geomagnetic activity is much larger than the uncertainty due

P. Blum; W. Priester; K. Schuchardt; C. Wulf-Mathies

1976-01-01

351

A performance analysis of the IRIDIUM® low earth orbit satellite system with a degraded satellite constellation  

Microsoft Academic Search

There are currently several commercial Low Earth Orbit (LEO) satellite systems under development that will provide worldwide voice, data, facsimile, and paging services. This article presents a performance analysis of the IRIDIUM® LEO satellite system, as several satellites become non-operational. The analysis is conducted using a computer simulation of the system. First, it examines the system's capability to meet real-time

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

1998-01-01

352

Application of the Satellite Gravity Gradiometry to the satellite orbits analysis  

Microsoft Academic Search

The presented work contains the theoretical aspects and simulation research of the satellite orbits determination by means of the Satellite Gravity Gradiometry (SGG) observations. In the first part of this work the Satellite Gravity Gradiometry description is given. This part presents the SGG as a perspective observation technique, which enables the gravity tensor measurement by means of the gradiometer located

Andrzej Bobojc; Andrzej Drozyner

2001-01-01

353

Packet routing algorithm for polar orbit LEO satellite constellation network  

Microsoft Academic Search

Broadband satellite networks are capable of providing global coverage and support various services. The networks constructed\\u000a by Low Earth Orbit (LEO) satellite constellations have attracted great interests because of their short round-trip delays\\u000a and wide bandwidths. A challenging problem is to develop a simple and efficient packet routing algorithm for the LEO satellite\\u000a constellation network. This paper presents a SpiderWeb

Kaidong Wang; Kechu Yi; Bin Tian; Chengke Wu

2006-01-01

354

Precise Orbit Determination for the GOCE Satellite Using GPS  

NASA Astrophysics Data System (ADS)

Apart from the gradiometer as the core instrument the first ESA Earth Explorer Core mission GOCE Gravity field and steady-state Ocean Circulation Explorer carries a 12-channel GPS receiver dedicated for precise orbit determination POD of the satellite The EGG-C European GOCE Gravity-Consortium led by the Technical University in Munich is building the GOCE HPF High-level Processing Facility dedicated to the Level 1b to Level 2 data processing One of the tasks of this facility is the computation of the Precise Science Orbit PSO for GOCE The PSO includes a reduced-dynamic and a kinematic orbit solution The baseline for the PSO is a zero difference procedure using GPS satellite orbits clocks and Earth Rotation Parameters ERPs from CODE Center for Orbit Determination in Europe one of the IGS International GNSS Service Analysis Centers The scheme for reduced-dynamic and kinematic orbit determination is based on experiences gained from CHAMP and GRACE POD and is realized in one processing flow Particular emphasis is put on maximum consistency in the analysis of day-boundary overlapping orbital arcs as well as on the higher data sampling rate and on differences originating from different GPS antenna configuration We focus on the description of the procedure used for the two different orbit determinations and on the validation of the procedure using real data from the two GRACE satellites as well as simulated GOCE data

Bock, H.; Jäggi, A.; Svehla, D.; Beutler, G.; Hugentobler, U.; Visser, P.

355

Earth System: Satellites  

NSDL National Science Digital Library

There are thousands of artificial satellites circling our planet for navigation, communications, entertainment, and science. These satellites are an integral part of our everyday life, and they collect data which cannot be obtained from Earth's surface. This video segment describes the basic components of a satellite and some of applications that have been developed for both geostationary and orbiting satellites. The segment is three minutes fifty seconds in length. A background essay and discussion questions are included.

356

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

NASA Astrophysics Data System (ADS)

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.

Parks, Lisa Ann

357

A census of orbital properties of the M31 satellites  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

358

WARC and CCIR support for spectrum-orbit planning  

NASA Technical Reports Server (NTRS)

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.

Sawitz, P. H.

1980-01-01

359

Satellite observations of CO2 from a highly elliptical orbit for studies of the Arctic and boreal carbon cycle  

NASA Astrophysics Data System (ADS)

we report on an observing system simulation experiment (OSSE) to compare the efficacy of near-infrared satellite observations of CO2 from a highly elliptical orbit (HEO) and a low Earth orbit (LEO), for constraining Arctic and boreal CO2 sources and sinks. The carbon cycle at these latitudes (~50-90°N) is primarily driven by the boreal forests, but increasing anthropogenic activity and the effects of climate change such as thawing of permafrost throughout this region could also have an important role in the coming years. A HEO enables quasi-geostationary observations of Earth's northern high latitudes, which are not observed from a geostationary orbit. The orbit and observing characteristics for the HEO mission are based on the Weather, Climate and Air quality (WCA) concept proposed for the Polar Communications and Weather (PCW) mission, while those for the LEO mission are based on the Greenhouse gases Observing Satellite (GOSAT). Two WCA instrument configurations were investigated. Adopting the Optimal configuration yielded an observation data set that gave annual Arctic and boreal regional terrestrial biospheric CO2 flux uncertainties an average of 30% lower than those from GOSAT, while a smaller instrument configuration resulted in uncertainties averaging 20% lower than those from GOSAT. For either WCA instrument configuration, much greater reductions in uncertainty occur for spring, summer, and autumn than for winter, with Optimal flux uncertainties for June-August nearly 50% lower than from GOSAT. These findings demonstrate that CO2 observations from HEO offer significant advantages over LEO for constraining CO2 fluxes from the Arctic and boreal regions.

Nassar, Ray; Sioris, Chris E.; Jones, Dylan B. A.; McConnell, John C.

2014-03-01

360

Tether de-orbiting of satellites at end of mission  

NASA Astrophysics Data System (ADS)

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

Sanmartin, Juan R.; Sánchez-Torres, Antonio

2012-07-01

361

A systematic method of generating Galilean satellite-to-satellite transfers for Orbiter/Lander missions  

NASA Technical Reports Server (NTRS)

A Galilean satellite tour design strategy is presented which minimizes the approach velocities at the target satellites. A technique is developed such that once a Hohmann transfer is established between any two adjacent Galilean satellites, transfer trajectories to the remaining Galilean satellites can be derived in a systematic manner. A relationship between spacecraft orbital period and perijove radius is used to develop an algorithm which produces transfer trajectories by simply accounting for the satellites' angular position. The algorithm is incorporated into a FORTRAN code which demonstrates that a finite number of realizable trajectories exist in the specialized Galilean satellite tours due to resonance phasing. The basic assumption is made that the orbits of all the Galilean satellites are circular and coplanar.

Soldner, J. K.; Feingold, H.

1981-01-01

362

LARES successfully launched in orbit: Satellite and mission description  

NASA Astrophysics Data System (ADS)

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.

Paolozzi, Antonio; Ciufolini, Ignazio

2013-10-01

363

Methods for predicting satellite orbital lifetimes  

Microsoft Academic Search

Simple graphical methods are presented for estimating the future lifetime of an earth satellite from its current rate of decay, using theory adapted to an atmosphere with a realistic variation of density with height. The effects of the departure of the earth and atmosphere from spherical symmetry and the variations of density with time are approximated by specifying correction factors.

D. G. King-Hele

1978-01-01

364

Stability Analysis of Planetary Satellite Orbiters: Application to the Europa Orbiter  

Microsoft Academic Search

Thestabilityoforbit dynamicsaround a planetary satelliteisstudied usinganalyticaland numerical techniques. The Europa orbiter mission is used to motivate our analysis and to provide specié c numerical data for verié cation of our analytical results. After veriécation, the results are applied to a large number of planetary satellites in the solar system. The motivation is that numerically integrated, low-altitude spacecraft orbits about Europa

D. J. Scheeres; M. D. Guman; B. F. Villac

2001-01-01

365

High-Resolution Satellite Imagery for Mesoscale Meteorological Studies.  

NASA Astrophysics Data System (ADS)

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), Lands at, and Satellite Pour I'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.

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

1994-01-01

366

Orbit determination accuracies using satellite-to-satellite tracking. [applicable to the Tracking and Data Relay Satellite system  

NASA Technical Reports Server (NTRS)

The results of the ATS-6/GEOS-3 and the ATS-6/NIMBUS-6 satellite-to-satellite tracking orbit determination experiments are reported. The tracking systems used in these experiments differ from the Tracking and Data Relay Satellite System (TDRSS), primarily in the use of one rather than two synchronous relay satellites. However, the simulations mentioned indicate that the insights gained from the experiments with regard to proper data reduction techniques and expected results are applicable to the TDRSS.

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

1978-01-01

367

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

368

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

Federal Register 2010, 2011, 2012, 2013

...IB Docket No. 12-376; FCC 12-161] Earth Stations Aboard Aircraft Communicating With...establishes technical and licensing rules for Earth Stations Aboard Aircraft (ESAA), i.e., earth stations on aircraft communicating with...

2013-03-08

369

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

Federal Register 2010, 2011, 2012, 2013

...IB Docket No. 12-376; FCC 12-161] Earth Stations Aboard Aircraft Communicating...proposal to elevate the allocation status of Earth Stations Aboard Aircraft (ESAA) in the...11.7-12.2 GHz band (space-to-Earth), on an unprotected basis in...

2013-03-08

370

Relative motion of near orbiting satellites.  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

371

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

ERIC Educational Resources Information Center

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…

Nous, Albert P.

372

Satellite probes plasma processes in earth orbit  

NASA Technical Reports Server (NTRS)

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.

Christensen, Andrew B.; Reasoner, David L.

1992-01-01

373

Satellite power systems \\/SPS\\/ overview  

Microsoft Academic Search

The concept of using a number of very large satellites in geostationary equatorial orbit to convert solar energy into electricity and then to microwave energy transmitted back to earth is given a brief historical overview. The major program elements and organizational responsibilities in the DOE\\/NASA program for satellite power systems are schematized. The timetable calls for preliminary program recommendations in

R. I. Larock

1978-01-01

374

G-MG Satellite  

NSDL National Science Digital Library

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

375

SMART-OLEV—An orbital life extension vehicle for servicing commercial spacecrafts in GEO  

Microsoft Academic Search

Orbital Satellite Services Limited (OSSL) is a satellite servicing company that is developing an orbit life extension vehicle (OLEV) to extend the operational lifetime of geostationary satellites. The industrial consortium of SSC (Sweden), Kayser-Threde (Germany) and Sener (Spain) is in charge to develop and industrialize the space and ground segment. It is a fully commercial program with support of several

Clemens Kaiser; Fredrik Sjöberg; Juan Manuel Delcura; Baard Eilertsen

2008-01-01

376

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

NASA Technical Reports Server (NTRS)

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).

1974-01-01

377

The simulation of satellite tracking and orbit prediction considering the swaths  

Microsoft Academic Search

A simulation system is developed for satellite tracking and orbit prediction. The program displays the location of Earth satellites and predicts the location of any satellite at any time. And the simulation of satellite tracking and orbit prediction take the swaths into consideration. The orbit prediction model and Two-Line Element (TLE) Sets are present first, and the Simplified General Perturbations

Lei Cai; Jianya Gong

2008-01-01

378

Centriolar satellites: busy orbits around the centrosome.  

PubMed

Since its first description by Theodor Boveri in 1888, the centrosome has been studied intensely, and it revealed detailed information about its structure, molecular composition and its various functions. The centrosome consists of two centrioles, which generally appear in electron microscopy as barrel-shaped structures usually composed of nine microtubule triplets. An amorphous mass of pericentriolar material surrounds the centrioles and accumulates many proteins important for the integrity and function of centrosomes, such as the ?-tubulin ring complex (?-TuRC) that mediates microtubule nucleation and capping. In animal somatic cells, the centrosome generally accounts for the major microtubule organizing center, and the duplicated pair of centrosomes determines the poles of the microtubule-based mitotic spindle. Despite detailed insights into the centrosome's structure and function, it has been a complete mystery until a few years ago how centrosomes duplicate and assemble. Moreover, it is still largely unclear if and how centrosomal proteins or protein complexes are exchanged, replaced or qualitatively altered. Previously identified cytoplasmic granules, named "pericentriolar" or "centriolar satellites", might fulfil such functions in protein targeting and exchange, and communication between the centrosomes and the cytoplasm. In this review, we summarize current knowledge about the structure, molecular composition and possible roles of the satellites that seem to surround the core of the centrosome in most animal cells. PMID:21945726

Bärenz, Felix; Mayilo, Dmytro; Gruss, Oliver J

2011-12-01

379

Reconstructing the orbit of the Chelyabinsk meteor using satellite observations  

NASA Astrophysics Data System (ADS)

The large number of objects in a range of orbits around the Sun means that some will inevitably intersect the Earth, becoming a meteor. These objects are commonly comet fragments or asteroids. To determine the type of a particular meteor requires knowledge of its trajectory and orbital path that is typically estimated by using ground-based observations such as images or radar measurements. A lack of data can, however, make this difficult and create large uncertainties in the reconstructed orbit. Here I show a new method for estimating a meteor's trajectory, and hence allowing computation of the orbit, based upon measurements from satellite sensors. The meteor that fell on 15 February 2013 is used as an example and the resulting orbit is in broad agreement with estimates from other observations. This new technique represents an alternative method for trajectory determination that may be particularly useful in areas where ground-based observations are sparse.

Proud, S. R.

2013-07-01

380

Precise Orbit Determination of Earth's Satellites for Climate Change Investigation  

NASA Astrophysics Data System (ADS)

The tremendous improvement of the gravity field models which we are achieving with the last Earth's satellite missions like, CHAMP, GRACE and GOCE devoted to its recovery could make feasibile the use of precise orbit determination (POD) of Earth satellites as a tool for sensing global changes of some key atmosphere parameters like refractivity and extinction. Such improvements indeed, coupled with the huge number of running Earth's satellites and combinations of their orbital parameters (namely the nodes) in a gravity field free fashion (hereafter GFF) can magnify the solar radiation pressure acting on medium earth orbit satellites :GPS, Etalon and, in near real future GALILEO and its smooth modulation through the Earth's atmosphere (penumbra). We would remind that The GFF technique is able to cancel out with "n" satellite orbital parameters the first n-1 even zonal harmonics of the gravity field. Previously it was demonstrated that the signal we want to detect could in principle emerge from the noise threshold but, more refined models of the atmosphere would be needed to perform a more subtle analysis. So we will re-compute the signal features of penumbra by applying more refined atmospheric models. The analysis will be performed by including in GFF Earth's satellites equipped with DORIS systems (Jason, Spot 2-3-4-5, ENVISAT etc.) other than those ranged with SLR and GPS. The introduction of DORIS tracked satellites indeed will allow to cancel higher and higher order of even zonal harmonics and will make still more favourable the signal to noise budget. The analysis will be performed over a time span of at least few tens of years just to enhance probable climate signatures.

Vespe, Francesco

381

Combined orbit determination satellite-network precision analysis based on whole network adjustment algorithm  

Microsoft Academic Search

For LEO orbit determination based on Bi-satellite Positioning System (BPS), trajectory error of positioning satellites becomes bottle-neck which improves orbit precision of LEO, so we can take combined orbit determination strategy of BPS and user satellites (LEO) to ameliorate precision. This paper integrates whole network adjustment algorithm into satellite precise orbit determination technology, and brings forward multi-LEO combined orbit determination

Deyong Zhao; Xiaogang Pan; Haiyin Zhou; Zhengming Wang

2005-01-01

382

Quasi-satellite Orbits in the Context of Coorbital Dynamics  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

383

Observations of orbital debris and satellites in Slovak Republic  

NASA Astrophysics Data System (ADS)

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.

Silha, Jiri; Toth, Juraj

384

Improving satellite vulnerability assessment to untrackable orbital debris  

NASA Astrophysics Data System (ADS)

The projected growth in the untrackable orbital debris population will place an increased emphasis on satellite vulnerability assessments during both design and mission operations. This study presents an enhanced method for assessing satellite vulnerability to untrackable orbital debris that expands on traditional practices. By looking beyond structural penetration of the spacecraft, the method predicts the survivability of individual components and the associated degradation of system functionality resulting from untrackable debris impacts. A new risk assessment tool, the Particle Impact Risk and Vulnerability Assessment Tool (PIRAT), has been developed based on this method and is also presented here. It interfaces with both the NASA ORDEM2000 and ESA MASTER-2009 debris models and has been validated against the benchmark test cases from the Inter-Agency Space Debris Coordination Committee (IADC). This study concludes with an example vulnerability assessment using PIRAT for a generic Earth observation satellite in a Sun-synchronous low-Earth orbit. The results illustrate the additional insight provided by this method that can be used to improve the robustness of future satellite designs and mitigate the overall mission risk posed by untrackable orbital debris.

Welty, Nathan; Schaefer, Frank; Rudolph, Martin; Destefanis, Roberto; Grassi, Lilith

2012-07-01

385

Orbital radiation exposure of the Astronomical Netherlands Satellite (ANS)  

NASA Technical Reports Server (NTRS)

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.

Stassinopoulos, E. G.

1971-01-01

386

Dynamical model compensation for near-earth satellite orbit determination  

Microsoft Academic Search

Operational requirements in modern space applications often demand orbit determination accuracies which are limited by fundamental mathematical and computational restrictions. It is shown in realistic computer simulation studies how these difficulties can be alleviated for typical near-earth satellites by employing dynamical model compensation (DMC) and accurate observations in the extended Kalman filter. Unmodeled and unknown accelerations affecting the motion of

K. A. Myers; B. D. Tapley

1975-01-01

387

Application of KAM Theorem to Earth Orbiting Satellites.  

National Technical Information Service (NTIS)

An orbit that lies on a Kolmogorov, Arnold, and Moser (KAM) Torus will remain on that torus until and unless it experiences a force that causes it to leave the torus. Earth satellites that are subject only to the Earth's gravity field may lie on such KAM ...

B. D. Little

2009-01-01

388

Solar cell coverglasses for satellites in the intermediate Earth orbit  

Microsoft Academic Search

Satellites in an Earth orbit where high levels of radiation are experienced require greater protection for their solar cell arrays than is normal. This may be provided by the use of thicker coverglasses to minimise solar cell degradation. This paper describes the development by Pilkingtons of a new glass CMO, which has a high transmission in the visible spectrum, is

C. Kitchen; K. Mullaney; M. Price; A. Dollery; K. Fyles; H. Eaves; R. Crabb; P. Bula

1997-01-01

389

Autonomous robotic operations for on-orbit satellite servicing  

NASA Astrophysics Data System (ADS)

The Orbital Express Demonstration System (OEDS) flight test successfully demonstrated technologies required to autonomously service satellites on-orbit. The mission's integrated robotics solution, the Orbital Express Demonstration Manipulator System (OEDMS) developed by MDA, performed critical flight test operations. The OEDMS comprised a six-jointed robotic manipulator arm and its avionics, non-proprietary servicing and ORU (Orbital Replacement Unit) interfaces, a vision and arm control system for autonomous satellite capture, and a suite of Ground Segment and Flight Segment software allowing script generation and execution under supervised or full autonomy. The arm was mounted on ASTRO, the servicer spacecraft developed by Boeing. The NextSat, developed by Ball Aerospace, served as the client satellite. The OEDMS demonstrated two key goals of the OEDS flight test: autonomous free-flyer capture and berthing of a client satellite, and autonomous transfer of ORUs from servicer to client and back. The paper provides a description of the OEDMS and the key operations it performed.

Ogilvie, Andrew; Allport, Justin; Hannah, Michael; Lymer, John

2008-05-01

390

Laser beaming demonstrations to high-orbit satellites.  

National Technical Information Service (NTIS)

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 demonstr...

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

1993-01-01

391

Adaptive signal processing for low Earth orbit satellite communications  

Microsoft Academic Search

Small link margins, multipath fading and human body effects degrade the performance of low Earth orbit satellite (LEOS) handheld terminals. Adaptive antennas take the rapidly changing environment and human body influence into account to maximise the final signal to interference plus noise ratio (STNR). The proposed reception system for LEOS handsets is an adaptive antenna system with an electric field

Faith Choy; M. Cherniakov

1998-01-01

392

Optical Dynamic Assignment for Low Earth Orbit Satellite Constellations.  

National Technical Information Service (NTIS)

In this paper we investigate autonomous task assignment for a group or low-earth orbit satellites that don't necessarily have prior knowledge or the targets or interest. Specifically, we consider the optimal assignment problem for dynamic weighted biparti...

A. Melin K. S. Erwin V. Chellaboina

2005-01-01

393

Space Environment Simulation to Test Satellite Thermal Control Coatings, Volume 1.  

National Technical Information Service (NTIS)

Simultaneous irradiation of satellite thermal control coatings by electrons, protons, and ultraviolet radiation, simulating 5 yr in geostationary orbit, was carried out. A layer of contaminant, originating from adhesive RTV566 by molecular flux, was appli...

M. Dutat J. Marco A. Paillous

1985-01-01

394

Satellite Network Performance Measurements Using Simulated Multi-User Internet Traffic.  

National Technical Information Service (NTIS)

As a number of diverse satellite systems (both Low Earth Orbit and Geostationary systems) are being designed and deployed, it becomes increasingly important to be able to test these systems under realistic traffic loads. While software simulations can pro...

H. Kruse M. Allman J. Griner S. Ostermann E. Helvey

1999-01-01

395

An Earth orbiting satellite service and repair facility  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

396

Coupled orbital-thermal evolution of the main Uranian satellites  

NASA Astrophysics Data System (ADS)

Some of the main satellites of Uranus, in particular Miranda and Ariel, present evidence of a past geophysical activity. This activity can be associated with internal heating during its history and several causes for this heating are envisaged, like the tides and impact(s), following radiogenic heating at the early stage of the evolution. Here, we present a coupled thermal-orbital model of the history of the main satellites of Uranus, in which not only the orbit acts on the heating, but the heating acts also on the orbit in affecting tidal dissipation. We focus in particular on the past mean-motion resonance Miranda-Umbriel, responsible for Miranda's current high inclination.

Noyelles, B.; Verheylewegen, E.; Karatekin, O.

2013-12-01

397

Small satellite characterization technologies applied to orbital debris  

NASA Astrophysics Data System (ADS)

There are challenges associated with optical observations of Earth-orbiting objects that are at, or near, the limit of detection using terrestrial space surveillance sensors. These challenges include observing small objects not just for statistical purposes, but also with enough frequency and accuracy to move them into satellite catalogs, to provide the capability to routinely observe and characterize smaller objects, and to develop the capability to observe the satellite positions with increased accuracy. Until recently, ground-based observers could easily have mistaken such small objects as debris. Given the current pace of small satellite development, it may not be much longer before operational spacecraft of even smaller size are launched. AMOS is currently developing techniques to observe and characterize these small spacecraft, and applying those techniques to orbital debris.

Kervin, P. W.; Africano, J. L.; Sydney, P. F.; Hall, D.

398

Interim Definitive Orbit for the Satellite 1958-Alpha, Explorer-1  

NASA Technical Reports Server (NTRS)

A summary of certain position information indicating accuracies for the orbital arcs underlying the ephemeris is presented in table 1. The detailed ephemeris information is presented at the end of this report in the form of tables which give the latitude and longitude of the subsatellite point and the satellite height for each minute of time. The subsatellite point is defined here as the point on the earth's surface over which the satellite was determined to be at the indicated time. The form of presentation was recommended by the International Geophysical Year agencies concerned, for use in specifying the orbital positions of IGy satellites. Time is specified by giving in columns, the day, hour, and minute of Greenwich mean time.

1960-01-01

399

Planning satellite communication services and spectrum-orbit utilization  

NASA Technical Reports Server (NTRS)

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

Sawitz, P. H.

1982-01-01

400

Advances in precision orbit determination of GRACE satellites  

NASA Astrophysics Data System (ADS)

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.

Bettadpur, Srinivas; Save, Himanshu; Kang, Zhigui

401

Geostationary Earth Radiation Budget (GERB) data  

Microsoft Academic Search

The Geostationary Earth Radiation Budget GERB instrument on METEOSAT 8 is designed to provide an accurate measure of the reflected solar and emitted thermal energy from a geostationary orbit GERB data products consist of broadband radiances and fluxes every 15 minutes for the whole METEOSAT 8 region The GERB data provide the first broadband measurements of the radiation budget at

J. E. Russell; J. E. Harries

2006-01-01

402

Geostationary Earth Radiation Budget (gerb): Validation Results  

Microsoft Academic Search

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

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

2006-01-01

403

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

NASA Technical Reports Server (NTRS)

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.

Pritchard, E. I.

1978-01-01

404

An overview of the Korea multi-purpose satellite (KOMPSAT)  

Microsoft Academic Search

Korea has initiated its own space program since 1990, successfully launching its first microsatellite into the earch orbit in 1992, and scientific sounding rockets in 1993. Broadcast and communications satellites were launched in geostationary orbit in 1995. A multipurpose satellite, KOMPSAT is under the joint-development with an American company with its launch target in mid 1999. Recently, the national space

Byung Kyo Kim

1999-01-01

405

Control System and Flexible Satellite Interaction During Orbit Transfer Maneuver  

NASA Technical Reports Server (NTRS)

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.

daSilva, Adenilson Roberto; GadelhadeSouza, Luiz Carlos

1998-01-01

406

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)

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.

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

2001-01-01

407

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

NASA Technical Reports Server (NTRS)

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.

Motamedi, Masoud; Estabrook, Polly

1990-01-01

408

Advanced Communications Technology Satellite Now Operating in an Inclined Orbit  

NASA Technical Reports Server (NTRS)

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

Bauer,