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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

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

3

Geostationary Earth Orbit Satellite Model using Easy Java Simulation  

NSDL National Science Digital Library

A paper from the Journal of Physics Teaching Online that describes an Easy Java Simulation (EJS) model that helps students visualize geostationary orbits near Earth. The simplified physics model is described and simulated using simple constant angular velocity equation. Four computer model design ideas such as 1) simple and realistic 3D view and associated learning to real world, 2) comparative visualization of permanent geostationary satellite 3) examples of non-geostationary orbits of different 3-1) rotation sense, 3-2) periods, 3-3) planes and 4) incorrect physics model for conceptual discourse are discussed.

Wee, Loo K.

2014-02-15

4

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

Code of Federal Regulations, 2012 CFR

...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed Satellite Service...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed Satellite Service...non-Federal-Government NGSO FSS satellite networks operating in the following assigned...

2012-10-01

5

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

Code of Federal Regulations, 2013 CFR

...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed-Satellite Service...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed-Satellite Service...non-Federal-Government NGSO FSS satellite networks operating in the following assigned...

2013-10-01

6

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

Code of Federal Regulations, 2011 CFR

...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed Satellite Service...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed Satellite Service...non-Federal-Government NGSO FSS satellite networks operating in the following assigned...

2011-10-01

7

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

Code of Federal Regulations, 2010 CFR

...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed Satellite Service...Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed Satellite Service...non-Federal-Government NGSO FSS satellite networks operating in the following assigned...

2010-10-01

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

Precise Orbit Propagation of Geostationary Satellite Using Cowell's Method  

NASA Astrophysics Data System (ADS)

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

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

1997-06-01

10

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

Microsoft Academic Search

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

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

1987-01-01

11

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

Federal Register 2010, 2011, 2012, 2013

...Fixed-Satellite Service Geostationary-Orbit Space Stations AGENCY: Federal Communications...Service (FSS) geostationary-orbit (GSO) space stations operating in the 10.95-11...45-11.7 GHz, 11.7-12.2 GHz (space-to-Earth or downlink) and...

2013-03-08

12

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

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

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, David; Worden, Helen

16

Precise Orbit Propagation of Geostationary Satellite Using Cowell's Method  

Microsoft Academic Search

To calculate the position and velocity of the artificial satellite precisely, one has to broil a mathematical model concerning the perturbations by understanding and analysing the space environment correctly and then quantifying. Due to these space environment model, the total acceleration of the artificial satellite can be expressed as the 2nd order differential equation and we build an orbit propagation

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

1997-01-01

17

A Multiple GNSS-based Orbit Determination Algorithm for Geostationary Satellites  

Microsoft Academic Search

The application of Global Positioning System (GPS) technology to the Geostationary Earth Orbit (GEO) determination has been constrained by the poor satellite visibility and weak signal power. This situation is expected to improve when multi-constellation Global Navigation Satellite Systems (GNSS) are available in the future. This paper aims to investigate a navigation algorithm to determine the GEO state vector in

Li Qiao; Samsung Lim; Chris Rizos; Jianye Liu

2009-01-01

18

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

Federal Register 2010, 2011, 2012, 2013

...Fixed-Satellite Service Geostationary-Orbit Space Stations AGENCY: Federal Communications...be authorized to communicate with GSO space stations of the FSS on a primary basis in the 11.7-12.2 GHz band (space-to-Earth), on an unprotected...

2013-03-08

19

The Geostationary Applications Satellite  

NASA Astrophysics Data System (ADS)

Berlin offers an in-depth look into all the engineering aspects of geostationary satellite design, construction, and launch. Geostationary satellites have opened new doors for the peaceful use of outer space. From vantage points 22,000 miles above the equator, they permit people anywhere on land, at sea, or in the air to communicate with each other, and they provide meteorologists, geologists, and other scientists with photographs of the earth. This book gives equal emphasis to the explanation of launch vehicles, orbital mechanics, the space environment, spacecraft structures, mechanisms, thermal control, telemetry tracking and command, communications technology, meterological payloads, product assurance and testing.

Berlin, Peter

2004-12-01

20

Insertion from Supersynchronous and Subsynchronous Transfer Orbit and navigation around active geostationary satellites encountered during station acquisition drift phase  

NASA Astrophysics Data System (ADS)

A method is described for the fast identification of optimal strategies for ground station-commanded geostationary satellite insertion by several apogee and/or perigee maneuvers performed with a restatable engine from the Transfer Orbit into any prescribed Near-Synchronous Drift Orbit, anticipating the delivery of the satellite by the launcher into a Supersynchronous, Geostationary or Subsynchronous Transfer Orbit. Sufficient simultaneous dual-site maneuver visibility, backup apogees/perigees, and optimal orbit inclination reduction is guaranteed. Additionally, an approach is described how station acquisition maneuvers, including orbit determination and thruster calibration aspects, as well as cross-coupling effects, can be scheduled and sized for the satellite rendezvous in the Near-Synchronous Drift Orbit with the on-station longitude in the Geostationary Orbit. Measures are described for navigating the satellite around other active geostationary satellites to its operational geographic longitude. Typical insertion and station acquisition examples, exercised at DLR-GSOC, will be presented.

Leibold, Alois F.

21

SILEX mission - First European experiment using optical frequencies between geostationary and low earth orbiting satellites  

NASA Astrophysics Data System (ADS)

Since 1982, CNES has investigated the possibility to relay data from a low earth orbiting satellite to the ground via a geostationary satellite through a high data rate optical link. This work has led to a collaboration between ESA and CNES to implement the Semiconductor Intersatellite Link experiment (SILEX) which involves two terminals, one on Artemis (ESA geostationary satellite) and one on SPOT-4 (French Earth Observation Satellite). This paper presents the technical baseline that has been selected for SILEX. A short discussion of the performance will be initiated mainly concerning the questions linked to interfaces with the host platforms and the expected communication performance. The areas of development that could help to define the next generation of optical communication experiments and applications are explored.

Faup, Michel; Laurent, Bernard; Pera, Luigi

1991-10-01

22

CARTEL: A method to calibrate S-band ranges with geostationary satellites. Results of orbit determination  

NASA Astrophysics Data System (ADS)

A satellite tracking campaign was organized, with 4 S-band stations, for 1 wk. The relative geometry of the network with respect to the satellites was an opportunity to show how the most precise orbit can be computed with the operational software. This precise orbit served as a reference to evaluate what can be achieved with one station with range and angular measurements, a typical configuration used for stationkeeping of geostationary satellites. Orbit computation implied numerical integration with gravitational (Earth, Moon, and Sun) and solar radiation pressure forces acting on the satellite. Arc lengths of 2 days gave initial state vectors which were compared every day. Precision of 10 m is achieved. However, an analysis of the influence of parameters in the orbit computations reveals that the absolute accuracy is of the order of 100 m, since modeling perturbations were neglected in the operational software (e.g., polar motion). In a relative sense, the reference orbit allows estimation of systematic errors for other tracking antennas.

Guitart, A.; Mesnard, B.

1986-05-01

23

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

24

VLBI Observations of Geostationary Satellites  

NASA Astrophysics Data System (ADS)

For a consistent realization of a Global Geodetic Observing System (GGOS), a proper tie between the individual global reference systems used in the analysis of space-geodetic observations is a prerequisite. For instance, the link between the terrestrial, the celestial and the dynamic reference system of artificial Earth orbiters may be realized by Very Long O Baseline Interferometry (VLBI) observations of one or several satellites. In the preparation phase for a dedicated satellite mission, one option to realize this is using a geostationary (GEO) satellite emitting a radio signal in X-Band and/or S-Band and, thus, imitating a quasar. In this way, the GEO satellite can be observed by VLBI together with nearby quasars and the GEO orbit can, thus, be determined in a celestial reference frame. If the GEO satellite is, e.g., also equipped with a GNSS-type transmitter, a further tie between GNSS and VLBI may be realized. In this paper, a concept for the generation of a radio signal is shown. Furthermore, simulation studies for estimating the GEO position are presented with a GEO satellite included in the VLBI schedule. VLBI group delay observations are then simulated for the quasars as well as for the GEO satellite. The analysis of the simulated observations shows that constant orbit changes are adequately absorbed by estimated orbit parameters. Furthermore, the post-fit residuals are comparable to those from real VLBI sessions.

Artz, T.; Nothnagel, A.; La Porta, L.

2013-08-01

25

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

NASA Astrophysics Data System (ADS)

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

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

26

Global-scale Observations of the Limb and Disk (GOLD) Mission: Science from Geostationary Orbit on-board a Commercial Communications Satellite  

NASA Astrophysics Data System (ADS)

Geostationary orbits are ideal for many science investigations of the Earth system on global scales. These orbits allow continuous observations of the same geographic region, enabling spatial and temporal changes to be distinguished and eliminating the ambiguity inherent to observations from low Earth orbit (LEO). Just as observations from geostationary orbit have revolutionized our understanding of changes in the troposphere, they will dramatically improve our understanding of the space environment at higher altitudes. However, geostationary orbits are infrequently used for science missions because of high costs. Geostationary satellites are large, typically weighing tons. Consequently, devoting an entire satellite to a science mission requires a large financial commitment, both for the spacecraft itself and for sufficient science instrumentation to justify a dedicated spacecraft. Furthermore, the small number of geostationary satellites produced for scientific missions increases the costs of each satellite. For these reasons, it is attractive to consider flying scientific instruments on satellites operated by commercial companies, some of whom have fleets of ~40 satellites. However, scientists' lack of understanding of the capabilities of commercial spacecraft as well as commercial companies' concerns about risks to their primary mission have impeded the cooperation necessary for the shared use of a spacecraft. Working with a commercial partner, the GOLD mission has successfully overcome these issues. Our experience indicates that there are numerous benefits to flying on commercial communications satellites (e.g., it is possible to downlink large amounts of data) and the costs are low if the experimental requirements adequately match the capabilities and available resources of the host spacecraft. Consequently, affordable access to geostationary orbit aboard a communications satellite now appears possible for science payloads.

Eastes, R.; Deaver, T.; Krywonos, A.; Lankton, M. R.; McClintock, W. E.; Pang, R.

2011-12-01

27

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

NASA Astrophysics Data System (ADS)

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

Montenbruck, Oliver

1991-02-01

28

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

29

Analysis of geostationary orbital slot availability for the SPS programme  

SciTech Connect

Analyses were carried out, using predicted future geostationary satellite numbers and distributions, to examine geostationary orbital slot availability on a global and domestic basis. The various international considerations applicable to the geostationary orbit are discussed, with particular attention being paid to potential conflict areas. The factors involved in the definition of geostationary satellite spacing conditions are described, and their effects analysed with respect to SPS. Three separate distribution characteristics are considered to estimate geostationary satellite numbers and distributions in 1991. From these distributions, predictions are made of orbital slot availability as a function of satellite spacing on a global basis, and also when applied specifically to the USA and W. Europe. In the European case, attempts are made to compare regional consumption area power density demands with potential orbital slot availability for the SPS.

Flower, R.J.

1981-01-01

30

Application of linear programming to final positioning (drift orbit) of a geostationary satellite  

NASA Astrophysics Data System (ADS)

Utilization of linear programming to optimize the fuel consumption of station acquisition while taking sensor visibilities into account is illustrated using TDF-1. The satellite uses solar measurement during orbit maneuvers which forbids thrust at some periods (sensor visibility). Linear programming allows changes in one type of constraint to be taken into account by modifying a general algorithm which describes all possible corrections. This flexibility has no effect on rapidity of calculation.

Blumstein, D.

31

The classical Laplace plane as a stable disposal orbit for geostationary satellites  

NASA Astrophysics Data System (ADS)

The classical Laplace plane is a frozen orbit, or equilibrium solution for the averaged dynamics arising from Earth oblateness and lunisolar gravitational perturbations. The pole of the orbital plane of uncontrolled GEO satellites regress around the pole of the Laplace plane at nearly constant inclination and rate. In accordance with Friesen et al. (1993), we show how this stable plane can be used as a robust long-term disposal orbit. The current graveyard regions for end-of-life retirement of GEO payloads, which is several hundred kilometers above GEO depending on the spacecraft characteristics, cannot contain the newly discovered high area-to-mass ratio debris population. Such objects are highly susceptible to the effects of solar radiation pressure exhibiting dramatic variations in eccentricity and inclination over short periods of time. The Laplace plane graveyard, on the contrary, would trap this debris and would not allow these objects to rain down through GEO. Since placing a satellite in this inclined orbit can be expensive, we discuss some alternative disposal schemes that have acceptable cost-to-benefit ratios.

Rosengren, Aaron J.; Scheeres, Daniel J.; McMahon, Jay W.

2014-04-01

32

Two-way time transfer experiments using an INTELSAT satellite in a inclined geostationary orbit  

Microsoft Academic Search

The Communications Research Laboratory (CRL) and Korea Research Institutes of Standards and Science (KRIS) had the opportunity to use satellites for the two-way time transfer experiment. CRL performed two kinds of Intelsat experiments: the ranging experiment and the Japanese domestic experiment. CRL and KRISS also performed a Japan-Korea joint international experiment. The results of these three experiments are described

Fujinobu Takahashi; Kuniyasu Imamura; Eiji Kawai; Chang Bok Lee; Dong Doo Lee; Nak Sam Chung; Hiroo Kunimori; Taizoh Yoshino; Toshimichi Otsubo; Atsushi Otsuka; Tadahiro Gotoh

1993-01-01

33

Geostationary satellite observations of dynamic phytoplankton photophysiology  

NASA Astrophysics Data System (ADS)

June 2010, the Geostationary Ocean Color Imager (GOCI) has been collecting the first diurnally resolved satellite ocean measurements. Here GOCI retrievals of phytoplankton chlorophyll concentration and fluorescence are used to evaluate daily to seasonal changes in photophysiological properties. We focus on nonphotochemical quenching (NPQ) processes that protect phytoplankton from high light damage and cause strong diurnal cycles in fluorescence emission. This NPQ signal varies seasonally, with maxima in winter and minima in summer. Contrary to expectations from laboratory studies under constant light conditions, this pattern is highly consistent with an earlier conceptual model and recent field observations. The same seasonal cycle is registered in fluorescence data from the polar-orbiting Moderate Resolution Imaging Spectroradiometer Aqua satellite sensor. GOCI data reveal a strong correlation between mixed layer growth irradiance and fluorescence-derived phytoplankton photoacclimation state that can provide a path for mechanistically accounting for NPQ variability and, subsequently, retrieving information on iron stress in global phytoplankton populations.

O'Malley, Robert T.; Behrenfeld, Michael J.; Westberry, Toby K.; Milligan, Allen J.; Shang, Shaoling; Yan, Jing

2014-07-01

34

Plasma propulsion for geostationary satellites for telecommunication and interplanetary missions  

NASA Astrophysics Data System (ADS)

The advantages of electric propulsion for the orbit maintenance of geostationary satellites for telecommunications are described. Different types of plasma sources for space propulsion are presented. Due to its large performances, one of them, named Hall effect thruster is described in detail and two recent missions in space (Stentor and Smart1) using French Hall thrusters are briefly presented.

Dudeck, M.; Doveil, F.; Arcis, N.; Zurbach, S.

2012-02-01

35

Resolution requirements for coastal applications of new geostationary satellites  

Microsoft Academic Search

For more than four decades, geostationary weather satellites have been used successfully by NOAA's National Weather Service for daily weather forecasting and for tracking storm events. At the same time, polar orbit systems, such as NOAA\\/AVHRR, SeaWIFS and Landsat TM, have provided valuable information about slowly varying features and processes in the open ocean and on land. However, coastal and

Vic Klemas

2005-01-01

36

Experience of eight geostationary satellite positionings  

NASA Astrophysics Data System (ADS)

Between October 1990 and August 1993, CNES has been involved in several geostationary Launch and Early Operations Phases (LEOP) of telecommunication satellites among which eight were based on the EUROSTAR platform: INMARSAT-2 F1, F2, F3 and F4, TELECOM 2A and 2B, HISPASAT 1A and 1B. During these operations, successfully performed in 34 months, the Flight Dynamics Center (FDC) faced various situations. After a brief description of each mission, this paper will give an analysis of the space dynamics results. This paper will also examine the lessons learned in areas such as operational preparation and organization and will suggest improvements for the two upcoming missions TELECOM 2C and 2D, also based on EUROSTAR platform or for other similar missions. Moreover, all the experience acquired during these eight LEOP allowed us to tune our software, to develop our engineer's know-how. This know-how and the numerous methods and software developed in CNES FDC were or will be also used for others LEOP ARABSATIC or TURKSAT LEOP. In addition, during all these LEOP the operational system and now the mission analysis system were based on the MERCATOR data processing system which by its redundancy, its modularity and its flexibility allows to a team of only four engineers to handle the space mechanics aspect of a complete geostationary positioning from injection in transfer orbit to the final maneuvers in the station keeping window.

Campan, Genvieve; Brousse, Pascal

37

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.

38

In-orbit radiometric performance variations of geostationary ocean color imager  

Microsoft Academic Search

Geostationary Ocean Color Imager (GOCI), a payload of the Communication, Ocean and Meteorology Satellite (COMS), is the world's first ocean color observation satellite in geostationary orbit. It was launched at Kourou Space Center in French Guiana in June 2010. The detector array in GOCI is custom CMOS Image sensor about 2 Mega-pixels, featuring rectangular pixel size to compensate for the

Sun-Ju Lee; Seongick Cho; Hee-Jeong Han; Eunsong Oh; Joo-Hyung Ryu; Yu-Hwan Ahn

2011-01-01

39

A multi-angle aerosol optical depth retrieval algorithm for geostationary satellite data over the United States  

Microsoft Academic Search

Aerosol optical depth (AOD) retrieval from geostationary satellites has high temporal resolution compared to the polar orbiting satellites and thus enables us to monitor aerosol motion. However, current Geostationary Operational Environmental Satellites (GOES) have only one visible channel for retrieving aerosol and hence the retrieval accuracy is lower than those from the multichannel polar-orbiting satellite instruments such as the Moderate

H. Zhang; A. Lyapustin; Y. Wang; S. Kondragunta; I. Laszlo; P. Ciren; R. M. Hoff

2011-01-01

40

Local Oscillator Distribution Using A Geostationary Satellite  

Microsoft Academic Search

A satellite communication system suitable for distribution of local oscillator reference signals for a widely spaced microwave array has been developed and tested experimentally. The system uses a round-trip correction method to remove effects of atmospheric fluctuations and radial motion of the satellite. This experiment was carried out using Telstar-5, a commercial Ku-band geostationary satellite. A typical Ku-band satellite has

J. Bardin; S. Weinreb; D. Bagri

2004-01-01

41

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

42

Remote sensing of aerosol and radiation from geostationary satellites  

Microsoft Academic Search

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

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

2006-01-01

43

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.

44

Local oscillator distribution using a geostationary satellite  

NASA Technical Reports Server (NTRS)

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

Bardin, Joseph; Weinreb, Sander; Bagri, Durga

2004-01-01

45

Geostationary Operational Environmental Satellite (GOES) Gyro Temperature Model  

NASA Technical Reports Server (NTRS)

The geostationary Operational Environmental Satellite (GOES) 1/M series of spacecraft are geostationary weather satellites that use the latest in weather imaging technology. The inertial reference unit package onboard consists of three gyroscopes measuring angular velocity along each of the spacecraft's body axes. This digital integrating rate assembly (DIRA) is calibrated and used to maintain spacecraft attitude during orbital delta-V maneuvers. During the early orbit support of GOES-8 (April 1994), the gyro drift rate biases exhibited a large dependency on gyro temperature. This complicated the calibration and introduced errors into the attitude during delta-V maneuvers. Following GOES-8, a model of the DIRA temperature and drift rate bias variation was developed for GOES-9 (May 1995). This model was used to project a value of the DIRA bias to use during the orbital delta-V maneuvers based on the bias change observed as the DIRA warmed up during the calibration. The model also optimizes the yaw reorientation necessary to achieve the correct delta-V pointing attitude. As a result, a higher accuracy was achieved on GOES-9 leading to more efficient delta-V maneuvers and a propellant savings. This paper summarizes the: Data observed on GOES-8 and the complications it caused in calibration; DIRA temperature/drift rate model; Application and results of the model on GOES-9 support.

Rowe, J. N.; Noonan, C. H.; Garrick, J.

1996-01-01

46

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

47

Accuracy of two-way satellite time and frequency transfer via non-geostationary satellites  

Microsoft Academic Search

In a manner different from the two-way satellite time and frequency transfer (TWSTFT) via geostationary satellites which has been employed for subnanosecond time transfer between widely separated earth stations, TWSTFT via non-geostationary satellites has a problem attaining subnanosecond accuracy because of satellite motion. The impact of satellite motion on the accuracy of TWSTFT via non-geostationary satellites is wholly attributed to

Shoichiro Yokota; Yasuhiro Takahashi; Miho Fujieda; Jun Amagai; Kazuhiro Kimura; Shin'ichi Hama

2005-01-01

48

The geostationary operational environmental satellite /GOES/ imaging communication system  

NASA Technical Reports Server (NTRS)

The SMS/GOES Satellite obtains day and night weather information from synchronous geostationary orbit by means of (1) earth imaging, (2) collection of environmental data from ground based sensors, platforms, and (3) monitoring of the space environment. SMS-1 and SMS-2 have been in orbit for 17 months and 8 months, respectively, and are presently taking full earth disk images in the visible and infrared every 30 minutes. SMS-1 is positioned to cover the eastern portion of the U.S. while SMS-2 is positioned to cover the western portion. This paper provides a general overview of the imaging communication portions of the SMS/GOES, related to the image data encoding and transmission as well as the method of the data time multiplexing and the manner in which the scan line to line synchronization is achieved.

Baker, W. L.; Savides, J.

1975-01-01

49

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

50

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

51

Studies of soundings and imagings measurements from geostationary satellites  

NASA Technical Reports Server (NTRS)

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

Suomi, V. E.

1973-01-01

52

High Speed Internet Access Through Unidirectional Geostationary Satellite Channels  

E-print Network

. Therefore, for large amounts of information the transfer time is too long. Developments in satellite user to a direct satellite channel, at a speed 20 times faster than that of an average telephone modemHigh Speed Internet Access Through Unidirectional Geostationary Satellite Channels Ina Minei Reuven

Cohen, Reuven

53

Study on image motion compensation technology for Chinese geostationary meterological satellite remote sensing  

Microsoft Academic Search

The new generation Chinese Geostationary Meteorological Satellite (CGMS) adopts three-axis stabilized attitude control mode, using many payloads, such as spaceborne imaging radiometer and atmospheric vertical sounder, etc, implements all weather and real-time observation to the atmospheric environment of the Earth. The deviation of the orbit results in the optical axis of the payloads to deviate its normal direction and then

Yinchao Chen; Zhigang Wang

2007-01-01

54

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

55

Frozen Orbital Plane Solutions for Satellites in Nearly Circular Orbit  

NASA Astrophysics Data System (ADS)

This paper deals with the determination of the initial conditions (right ascension of the ascending node and inclination) that minimize the orbital plane variation for nearly circular orbits with a semimajor axis between 3 and 10 Earth radii. An analysis of two-line elements over the last 40 years for mid-, geostationary-, and high-Earth orbits has shown, for initially quasi-circular orbits, low eccentricity variations up to the geostationary altitude. This result makes the application of mathematical models based on satellite circular orbits advantageous for a fast prediction of long-term temporal evolution of the orbital plane. To this purpose, a previous model considering the combined effect due to the Earth's oblateness, moon, and sun (both in circular orbit) has been improved in terms of required computational time and accuracy. The eccentricity of the sun and moon and the equinoctial precession have been taken into account. Resonance phenomena with the lunar plane motion have been found in mid-Earth orbit. Dynamical properties concerning the precession motions of the orbital pole have been investigated, and frozen solutions for geosynchronous and navigation satellites have been proposed. Finally, an accurate model validation has also been carried out by comparing the obtained results with two-line elements of abandoned geostationary-Earth orbit and mid-Earth orbit satellites.

Ulivieri, Carlo; Circi, Christian; Ortore, Emiliano; Bunkheila, Federico; Todino, Francesco

2013-08-01

56

Status of CNES optical observations of space debris in geostationary orbit  

NASA Astrophysics Data System (ADS)

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 has been studying and developing such systems for several years with two main objectives: first to develop systems able to detect debris in the vicinity of the geostationary orbit for statistical evaluation of the population, secondly to develop a tool to accurately determine the orbits: these activities are led in the frame of two projects called Tarot and Rosace. On one hand, the capability of detecting small objects in geostationary orbit was demonstrated during previous studies using a large Schmidt telescope. Now, the software has been transferred on a smaller telescope called Tarot. This telescope has the advantage to be automatic with a real time processing capability and can be remotely controlled. Moreover, its large field of view enables a systematic survey of the geostationary region to detect uncatalogued objects. Beside the detection function, a step by step orbit determination function is implemented. This function is necessary to find again the same object a few minutes or a few hours later. On the other hand, Rosace was designed as a low cost accurate orbit determination system for on-station geostationary satellites. The main application is the calibration of the classical tracking systems. The other objectives are to provide redundancy to existing facilities, to track failed satellites or to monitor co-located satellites. The first operational use is now foreseen in the frame of the Stentor project. This paper presents the main characteristics of both systems, the principle of their image processing software, their development status and the main results obtained. Finally, perspectives for further developments and coupling of the two systems are presented.

Alby, F.; Deguine, B.; Escane, I.

57

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

NASA Astrophysics Data System (ADS)

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.

1995-05-01

58

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

59

Meteosat Third Generation - the future European geostationary meteorological satellite  

NASA Astrophysics Data System (ADS)

Today, the Meteosat geostationary meteorological satellites play a key role in providing continuous atmospheric observations both for weather forecasting and for monitoring a wide variety of environmental phenomena. Following the successful commissioning of the first satellite in the Meteosat Second Generation (MSG) series, Eumetsat and ESA are already actively planning the next European operational geostationary meteorological satellite system in the form of the Meteosat Third Generation (MTG). Being considered for launch in 2015, MTG will revolutionise weather forecasting and environmental monitoring as we now know them, by providing a very significant improvement over the capabilities of the current Meteosats.

Bézy, Jean-Loup; Aminou, Donny; Bensi, Paolo; Stuhlman, Rolf; Tjemkes, Stephen; Rodriguez, Antonio

2005-08-01

60

Orbit analysis of a geostationary gravitational wave interferometer detector array  

E-print Network

We analyze the trajectories of three geostationary satellites forming the GEOstationary GRAvitational Wave Interferometer (GEOGRAWI)~\\cite{tinto}, a space-based laser interferometer mission aiming to detect and study gravitational radiation in the ($10^{-4} - 10$) Hz band. The combined effects of the gravity fields of the Earth, the Sun and the Moon make the three satellites deviate from their nominally stationary, equatorial and equilateral configuration. Since changes in the satellites relative distances and orientations could negatively affect the precision of the laser heterodyne measurements, we have derived the time-dependence of the inter-satellite distances and velocities, the variations of the polar angles made by the constellation's three arms with respect to a chosen reference frame, and the time changes of the triangle's enclosed angles. We find that, during the time between two consecutive station-keeping maneuvers (about two weeks), the relative variations of the inter-satellite distances do not...

Tinto, Massimo; Kuga, Helio K; Alves, Marcio E S; Aguiar, Odylio D

2014-01-01

61

a Study on Fuel Estimation Algorithms for a Geostationary Communication & Broadcasting Satellite  

NASA Astrophysics Data System (ADS)

It has been developed to calculate fuel budget for a geostationary communication and broadcasting satellite. It is quite essential that the pre-launch fuel budget estimation must account for the deterministic transfer and drift orbit maneuver requirements. After on-station, the calculation of satellite lifetime should be based on the estimation of remaining fuel and assessment of actual performance. These estimations step from the proper algorithms to produce the prediction of satellite lifetime. This paper concentrates on the fuel estimation method that was studied for calculation of the propellant budget by using the given algorithms. Applications of this method are discussed for a communication and broadcasting satellite.

Eun, Jong-Won

2000-12-01

62

Remote sensing of aerosol and radiation from geostationary satellites  

Microsoft Academic Search

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

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

2008-01-01

63

Study on image motion compensation technology for Chinese geostationary meterological satellite remote sensing  

NASA Astrophysics Data System (ADS)

The new generation Chinese Geostationary Meteorological Satellite (CGMS) adopts three-axis stabilized attitude control mode, using many payloads, such as spaceborne imaging radiometer and atmospheric vertical sounder, etc, implements all weather and real-time observation to the atmospheric environment of the Earth. The deviation of the orbit results in the optical axis of the payloads to deviate its normal direction and then the image quality becomes lower. To acquire high quality image, an algorithm of image motion compensation (IMC) is designed. Simulation results demonstrate that the proposed algorithm can effectively compensate the deviation of the optical axis from the motion of the satellite orbit.

Chen, Yinchao; Wang, Zhigang

2007-11-01

64

Land Surface Characterization with Japanese Geostationary Meteorological Satellite  

NASA Astrophysics Data System (ADS)

Japanese Geostationary Meteorological Satellite, Multi-functional Transport Satellite (MTSAT) which covers East Asia and the Western Pacific region from 140 degrees East above the equator was launched in February 2005. MTSAT is able to provide data every hour with 5 channels (VIS, IR1, IR2, IR3, IR4). Hourly measurement of MTSAT increase the chance of observing cloud-free land surface compared with those of polar-orbiting satellite, and enables to almost real-time monitoring. In this study, we developed pre-processing methodology for land surface monitoring implemented after radiometric and geometric corrections and create high-quality MTSAT dataset. Solar illumination is very variable both temporally and spatially because MTSAT is able to monitor huge area with high-frequency. As visible reflectance is largely dependent on intensity of incident solar radiation, quantitative analysis requires removal of the effect. And cloud and cloud shadow disturb acquisition of information on land surface condition from space. Hence, it is important to select and analyze fine pixels which are not contaminated with cloud and cloud shadow. Firstly, radiometric and geometric corrections were implemented by MTSAT pre-processing software namely mtsatgeo. Secondly, solar illumination effect in visible channel was corrected. After identify cloud- contaminated pixels by simple threshold method, cloud shadow position of each cloud-contaminated pixel was identified based on sun-target-sensor geometry. Then, cloud and cloud shadow were eliminated with daily compositing processing. Finally, spatio-temporal changes in visible reflectance and temperature were quantified and time-series behavior of them in each land cover was characterized.

Oyoshi, K.

2008-12-01

65

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

66

Equatorial long waves in geostationary satellite observations and in a multichannel sea surface temperature analysis  

NASA Technical Reports Server (NTRS)

Geostationary satellite observations of a zonally oriented sea surface temperature front in the eastern equatorial Pacific were made between 1975 and 1981. Long waves appeared along the front mainly during the summer and fall, except during 1976, the year of an El Nino. The waves have averaged periods of 25 days and wavelengths of 1000 km. At the end of 1981, the long waves also were detected in a new sea surface temperature analysis based on multichannel infrared measurements from a polar-orbiting satellite. This quantitative analysis may improve the ability to resolve low-frequency equatorial wave motions from satellite observations.

Legeckis, R.; Pichel, W.; Nesterczuk, G.

1983-01-01

67

New developments on atmospheric chemsitry remote sensing from geostationary orbit  

NASA Astrophysics Data System (ADS)

During the EUMETSATs post-MSG user consultation process requirements on measurements of the composition of the lower part of the atmosphere were identified and detailed in the last years. These requirements are mostly linked to the application area "Operational Chemical Applications and Air Quality monitoring". To address air quality issues from space there is a clear need for high spatially (< 10 km x 10 km) and temporally resolved (< hourly) measurements of the composition of the troposphere. This is recognised and described in a variety of documents issued by operational meteorological services like EUMETSAT, by governmental initiatives like GMES as well as by scientific initiatives. Nevertheless, no measurement system is currently in place to fulfil the relevant requirements. Measurements from Geostationary Orbit (GEO) offer a very attractive approach to the observation of the high tropospheric variability from space, as already demonstrated by meteorological applications. In response to the data needs, studies were performed during the last years to investigate the capabilities and technical feasibility of instrumentation and mission concepts in geostationary orbit to meet the above mentioned user requirements. This talk will summarise the results of a study investigating the capabilities of an instrument measuring the solar backscatter radiance to derive the chemical composition of the troposphere (O3, NO2, CO, HCHO, SO2, CO, Aerosol, etc.). The feasibility and limitations of the measurement concept will be discussed and it will be shown that important user requirements can be addressed and fulfilled by a geostationary atmospheric chemistry mission.

Bovensmann, H.; Eichmann, K. U.; Noel, S.; Rozanov, V.; Vountas, M.; Burrows, J. P.

68

CARTEL: A method to calibrate S-band ranges with geostationary satellites  

NASA Astrophysics Data System (ADS)

An intersite tracking campaign was organized, with 4 S-band stations, for a period of 1 wk to show how the most precise orbit can be computed with the operational software. This precise orbit served as a reference in order to evaluate what can be achieved with one single station with range and angular measurements (a typical configuration used for stationkeeping of geostationary satellites). Orbit computation implied numerical integration with gravitational (Earth, Moon, and Sun) and solar radiation pressure as forces acting on the satellite. Arc lengths of 2 days gave initial state vectors which were compared every day. A precision of 10 m is achieved. However, an analysis of the influence of several parameters entering the orbit computations reveals that the absolute accuracy is of the order of 100 m, since modeling perturbations were neglected in the operational software (polar motion for example). This reference orbit allows estimation of systematic errors for other tracking antennas.

Guitart, A.; Mesnard, R.; Nouel, F.

1986-12-01

69

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.

70

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

71

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

72

CNES organization for station positioning of geostationary satellites  

NASA Technical Reports Server (NTRS)

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

Dulac, Jean

1993-01-01

73

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

74

Torque compensation technology for the geostationary meteorological satellite  

NASA Astrophysics Data System (ADS)

To acquire high quality image, the new generation Geostationary Meteorological Satellite in China (GMSC) adopts three-axis stabilized attitude control mode, besides an advanced control system is required to be designed to get higher pointing precision and degree of stability of the satellite. However, the ability of the control system is limited. Torque compensation technology is studied in this paper aiming at rejecting the disturbance factors, which cannot be absorbed by the control system. In the research of torque compensation technology, the main factors that influence the degree of stability of satellite are analyzed; the objects compensated are confirmed through analysis of simulation; the system technical concept of torque compensation is designed; the mathematical models of the compensated objects and compensation devices are founded; the torque compensation arithmetic is designed; the valid arithmetic of torque compensation is proved through simulation. The research provides theoretical principles to develop the new generation GMSC.

Wang, Zhigang; Wang, Lusha; Chen, Shilu; Li, Qing

2009-12-01

75

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

E-print Network

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 disc containing one hundred 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 sma...

Weisberg, J M

2012-01-01

76

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

77

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

NASA Astrophysics Data System (ADS)

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

Barret, C.

1992-09-01

78

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

NASA Technical Reports Server (NTRS)

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

Suddeth, D. H.

1985-01-01

79

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

80

Coherent radar measurement of ocean currents from geostationary orbit  

NASA Technical Reports Server (NTRS)

A coherent HF radar system developed by Barrick has successfully measured ocean surface currents near shore. This innovative system, called CODAR, can map the current vector for coastal areas as large as 10,000 sq km. CODAR's range is limited owing to the strong attenuation suffered by HF ground waves. An alternate technique was proposed by Schuler, in which the cross-product power spectrum of two (different frequency) microwave signals is processed. The frequency of the resonant peak corresponds close by to the Doppler shift of an ocean gravity wave traveling toward the radar at the phase velocity, v(sub p). The slight difference between the frequency of the measured resonant delta K peak and the Doppler frequency shift caused by the motion of the gravity wave is attributed to be the current velocity in the pointing direction of the radar. The Microwave Remote Sensing Laboratory (MIRSL) has considered the feasibility of using this technique to measure ocean surface currents from geostationary satellite platforms. Problems are discussed that must be overcome if a satellite current measurement system is to be realized. MIRSL research activities that address some of these problem areas are discussed. Current measurements are presented that were made using a specially-designed C-Band, step-frequency delta K radar. These measurements suggest that progress is being achieved in detecting ocean surface current motion for a wide variety of ocean surface conditions.

Mcintosh, R. E.

1989-01-01

81

Differential spacecraft charging on the geostationary operational environmental satellites  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

82

Results of a study of on-board autonomous station keeping of geostationary satellites and its impact to ground systems  

NASA Astrophysics Data System (ADS)

The requirements of repetitive tracking, orbit determination and orbit corrections will be very high for future 3-axis stabilized geostationary satellites with station keeping tolerance windows around 0.1 deg. The feasibility and performance of a self-contained on-board system consisting of an earth sensor, several sun sensors, a Polaris sensor and an on-board clock are investigated. An epoch element filter along with a reasonable simple orbit model is used to evaluate the navigational information from the satellite attitude data. The orbit corrections are performed by a low thrust electric propulsion system according to an optimal strategy. A 1000 kg satellite with cross sectional area of about 50 m sq, as for the German/French TV-SAT to be positioned at 19 deg W, is assumed.

Leibold, A.; Eckstein, M.

83

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

84

Data management of geostationary communication satellite telemetry and correlation to space weather observations  

E-print Network

To understand and mitigate the effects of space weather on the performance of geostationary communications satellites, we analyze sixteen years of archived telemetry data from Inmarsat, the UK-based telecommunications ...

Lohmeyer, Whitney Quinne

2013-01-01

85

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

86

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

87

Land surface thermal characterization of Asian-pacific region with Japanese geostationary satellite  

NASA Astrophysics Data System (ADS)

Land Surface Temperature (LST) is a significant indicator of energy balance at the Earth's surface. It is required for a wide variety of climate, hydrological, ecological, and biogeochemical studies. Although LST is highly variable both temporally and spatially, it is impossible for polar-orbiting satellite to detect hourly changes in LST, because the satellite is able to only collect data of the same area at most twice a day. On the other hand, geostationary satellite is able to collect hourly data and has a possibility to monitor hourly changes in LST, therefore hourly measurements of geostationary satellite enables us to characterize detailed thermal conditions of the Earth's surface and improve our understanding of the surface energy balance. Multi-functional Transport Satellite (MTSAT) is a Japanese geostationary satellite launched in 2005 and covers Asia-Pacific region. MTSAT provides hourly data with 5 bands including two thermal infrared (TIR) bands in the 10.5-12.5 micron region. In this research, we have developed a methodology to retrieve hourly LST from thermal infrared data of MTSAT. We applied Generalized Split-window (GSW) equation to estimate LST from TIR data. First, the brightness temperatures measured at sensor on MTSAT was simulated by radiative transfer code (MODTRAN), and the numerical coefficients of GSW equation were optimized based on the simulation results with non-linear minimization algorithm. The standard deviation of derived GSW equation was less than or equal to 1.09K in the case of viewing zenith angle lower than 40 degree and 1.73K in 60 degree. Then, spatial distributions of LST have been mapped optimized GSW equation with brightness temperatures of MTSAT IR1 and IR2 and emissivity map from MODIS product. Finally, these maps were validated with MODIS LST product (MOD11A1) over four Asian-pacific regions such as Bangkok, Tokyo, UlanBator and Jakarta , It is found that RMSE of these regions were 4.57K, 2.22K, 2.71K and 3.92K, respectively. Large RMSEs of Bangkok and Jakarta in the tropical zone can be result from unsuitable parameters used in the MODTRAN simulations and remained haze or cirrus cloud. However, comparison between MTSAT LST and MODIS LST showed linearity and consistency, therefore MTSAT LST contribute to a better understanding in a wide variety of the surface energy balance research. Finally, thermal characterizations such as the rate of LST change or diurnal LST range and so on have been mapped by using constructed MTSAT LST database.

Oyoshi, K.; Tamura, M.

2010-12-01

88

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

89

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

90

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

Code of Federal Regulations, 2010 CFR

...meteorological satellite systems and non-voice, non-geostationary satellite systems in the 137-138 MHz band...SATELLITE COMMUNICATIONS Technical Standards § 25.259...meteorological satellite systems and non-voice,...

2010-10-01

91

Reference Crop Evapotranspiration obtained from the geostationary satellite MSG (METEOSAT).  

NASA Astrophysics Data System (ADS)

Among others, the scope of the Land Surface Analysis Satellite Applications Facility (LSA SAF) is to increase benefit from the EUMETSAT geostationary Satellites MSG data related to land, land-atmosphere interactions and biophysical applications. This is achieved by developing techniques, products and algorithms that will allow an effective use of MSG data, if needed, combined with data from numerical weather prediction models (e.g., ECMWF). Although directly designed to improve the observation of meteorological systems, the spectral characteristics, time resolution and area coverage offered by MSG allow for their use in a broad spectrum of other applications, for instance in agro- and hydrometeorology. This study concerns a method to determine how much water is needed for irrigation. Note that this is complementary to the actual evapotranspiration LSA SAF product. The objective of this study is to present a novel semi-empirical method to determine the Reference Crop Evapotranspiration (ET0) from the down-welling shortwave radiation and air temperature obtained through LSF SAF. ET0 is defined in the FAO Irrigation and Drainage report 56 (FAO56) and it is used to determine water requirements of agricultural crops in irrigated regions. It is evaluated with a special version of the Penman-Monteith equation (PM_FAO56) using data of a weather station installed over non-stressed grass. Such stations are expensive and very labor consuming. We developed our method for semi-arid regions where appropriate weather stations needed for FAO56 ET0 are missing. This concerns huge areas in the world. High-quality FAO-grass station near Cordoba, Spain were used, where, besides all input for PM-FAO56, independent lysimeter data are collected. In addition, it will be shown that significant errors in ET0 can occur if meteorological gathered over dry terrain will be used as input of PM-FAO56. For this purpose data sets obtained in different semi-arid regions will be analyzed.

de Bruin, H. A. R.; Trigo, I. F.; Lorite, I. J.; Cruz-Blanco, M.; Gavilán, P.

2012-04-01

92

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

NASA Astrophysics Data System (ADS)

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

Jasentuliyana, N.; Chipman, R.

93

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...

94

An LO Phase Link Using a Commercial Geo-Stationary Satellite  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

95

An application of a geostationary satellite rain estimation technique to an extratropical area  

NASA Technical Reports Server (NTRS)

Previous studies in which geostationary-satellite images were used for estimating precipitations dealt primarily with tropical clouds. In the present study, an attempt is made to evaluate the applicability of geostationary images and techniques in the Montreal area, characterized by a variety of weather situations and variables (different types of cloud, moisture and temperature profiles, and rain rates). The large differences between the Montreal and tropical studies are shown to be reflected by Simpson and Wiggert's (1969) cloud model.

Wylie, D. P.

1979-01-01

96

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

97

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

98

Early orbit determination  

Microsoft Academic Search

Orbit determination for near real time monitoring of satellite movement based on limited observations is discussed. For geostationary satellites this early orbit determination requirement arises after injection into geostationary transfer orbit, apogee motor firing, and larger orbit maneuvers during the on-station phase. Early orbit determination is hampered by the limited amount of data caused by nonavailability of the tracking system.

S. Pallaschke

1986-01-01

99

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

NASA Astrophysics Data System (ADS)

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 the field of Flight Dynamics, has a very extensive knowledge and broad base of experience in the field of space debris. This is due to its collaboration with the European Space Agency in this area over the last decade, as well as the development of customised solutions for operators such as EUTELSAT. At the beginning of 2003, GMV was awarded a contract by New Skies Satellites, a leading communications satellite operator based in The Hague, (The Netherlands), for the development of a customised tool for detection of close approaches between their satellites and third-party objects. This tool uses the information provided by USSTRATCOM as two-line elements (TLEs) plus the operational data available for the operator's satellites. The tool has eventually evolved into a generic product called focusCloseAp, which is commercialised like a COTS product in different versions, to provide operators with a cost-efficient solution for collision risk assessment. This paper presents the results of the experience obtained by New Skies Satellites while using focusCloseAp during the first year to obtain collision approach results automatically every night, the kind of problems encountered and the solutions that have been studied and / or applied. Some potential enhancements currently under consideration are also described. After running the program for 5 operational satellites during 5 months, 38 actual encounters have been found, yielding a trend of 1.5 encounters per month and satellite. focusCloseAp presents a great flexibility in its use and allows the user to modify the satellite orbital and manoeuvre parameters very easily and re-run different analysis cases to check the effects of the proposed modifications. This feature has been exploited at New Skies Satellites to find out that there are various options for altering the encounter geometry quite considerably. They will be presented in this paper. Moreover, when analysing the parameters altering the conjunction geometry, it has been found that a good planning of the operations is highly recommended to minimise the uncertainties. Differences between the planning and the actual operations can produce great variations of the geometry. Finally, the continuous use of TLEs has led to the detection of several problems that will be described in the paper along with the solutions that have been considered. Issues like precision of TLE propagation, sudden updates of TLEs inconsistent with previous sets and others are discussed.

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

100

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

E-print Network

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

Sun, Donglian

101

Martian satellite orbits and ephemerides  

NASA Astrophysics Data System (ADS)

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

Jacobson, R. A.; Lainey, V.

2014-11-01

102

Secular resonances as a source of dynamic chaoticity in the long-term orbital evolution of uncontrolled satellites  

NASA Astrophysics Data System (ADS)

We present the results of MEGNO analysis of the long-term orbital evolution of uncontrolled objects of satellite radio navigation systems in medium Earth orbits and geostationary orbits. It is shown that secular resonances affecting these objects may give rise to dynamic randomness in their long-term orbital evolution.

Bordovitsyna, T. V.; Tomilova, I. V.; Chuvashov, I. N.

2014-07-01

103

Irregular Satellites: Orbits and Origins  

Microsoft Academic Search

Each of the giant planets has irregular satellites, moons that occupy large orbits of significant eccentricity e and\\/or inclination i. Since 1997, when only 10 irregular satellites were known, 29 new ones have been discovered, allowing the dynamical structure of these systems to be discerned. The irregulars often lie close to the orbital stability limit, about 1\\/2-1\\/3 of the way

J. A. Burns; B. J. Gladman; P. D. Nicholson; R. A. Jacobson; V. Carruba; M. J. Holman; JJ Kavelaars

2001-01-01

104

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

NASA Astrophysics Data System (ADS)

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

Salemi, A.; Ruminski, M. G.

2012-12-01

105

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

106

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

107

Investigations on ionospheric electron content and electron density irregularities at low latitudes with geostationary satellites  

Microsoft Academic Search

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 anomaly indicate the importance of plasma transport in the equatorial ionosphere. Solar and geomagnetic controls also show some interesting features. It has been observed that

J. N. Bhar; S. Basu; A. Dasgupta; B. K. Guhathakurfa; G. N. Bhattacharyya

1976-01-01

108

Realizability research of work the geostationary satellite system in a limit range  

Microsoft Academic Search

Geostationary satellite system is used for years as world-range telecommunication system. In modernized marine radiocommunication system (GMDSS-Global Maritime Distress and Safety System) it is a basic technical structure, which gives automatically communication in global range. On account of its realizability the system is particularly important in case of necessity of correspondence during threatening the safety in marine and air transport.

P. Bojarski

2003-01-01

109

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

110

Operational aspects of the injection of spacecraft into geostationary orbit  

NASA Astrophysics Data System (ADS)

The characteristics and problems of various orbit injections are considered in terms of the initial conditions, final orbit, and attitude. The injection procedure consists of flight dynamics events that are dynamic (spin rate and attitude maneuvers, attitude acquisition maneuvers, and orbital maneuvers), preparation, monitoring, and analyses of the events, and estimation orbit and attitude state. Additional considerations of ABM firing attitude and time is necessary during transfer into GEO. Attention is given to spacecraft stabilization, attitude measurement and reaction control subsystems, and real-time operations of the ground segment. Selection of the subsystems configuration, launch window, and mission requirements, leads to further choices for the apogee of ABM ignition, restrictions on the solar angle, and accuracy goals for fuel conservation.

Muench, R. E.

111

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

112

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

NASA Astrophysics Data System (ADS)

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

Gan, Q. B.

2012-07-01

113

The East-West Effect in Solar Proton Fluxes in Geostationary Orbit: A New GOES Capability  

Microsoft Academic Search

Solar energetic protons have direct and rapid access to geostationary orbit (L = 6.6) and often to lower L shells, thereby presenting a severe space weather hazard throughout the magnetosphere. Starting with GOES 13, the GOES system has a new operational capability of co-located and simultaneous westward and eastward observations of 0.7-900 MeV solar proton fluxes. Due to the ~1

J. V. Rodriguez; T. G. Onsager; J. E. Mazur

2009-01-01

114

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

115

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

116

Investigation of mesoscale meteorological phenomena as observed by geostationary satellite  

NASA Technical Reports Server (NTRS)

Satellite imagery plus conventional synoptic observations were used to examine three mesoscale systems recently observed by the GOES-EAST satellite. The three systems are an arc cloud complex (ACC), mountain lee wave clouds and cloud streets parallel to the wind shear. Possible gravity-wave activity is apparent in all three cases. Of particular interest is the ACC because of its ability to interact with other mesoscale phenomena to produce or enhance convection.

Brundidge, K. C.

1982-01-01

117

Use of low orbital satellite communications systems for humanitarian programs  

NASA Technical Reports Server (NTRS)

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

Vlasov, Vladimir N.; Gorkovoy, Vladimir

1991-01-01

118

Image analysis of geostationary meteorological satellite for monitoring movement of mesoscale convective systems over Tibetan plateau  

Microsoft Academic Search

Disaster weather forecasting is becoming increasingly important. In this paper, the trajectories of Mesoscale Convective Systems\\u000a (MCSs) were automatically tracked over the Chinese Tibetan Plateau using Geostationary Meteorological Satellite (GMS) brightness\\u000a temperature (Tbb) from June to August 1998, and the MCSs are classified according to their movement direction. Based on these,\\u000a spatial data mining methods are used to study the

Zhong-yang Guo; Xiao-yan Dai; Wu Jian-ping; Lin Hui

2005-01-01

119

Use of Visible Geostationary Operational Meteorological Satellite Imagery in  

E-print Network

is typically computed at specific locations based on weather station data. Estimates of incoming solar determinant of spatial variation in these values, particularly in areas with heterogeneous cloud cover. RET continuous methods of computing RET and PET. A robust insolation calibration framework coupled to a satellite

120

NASA Now: Orbital Mechanics: Earth Observing Satellites  

NASA Video Gallery

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

121

A hindcast study using aerosol optical depth retrieved from a geostationary satellite sensor (GOCI) over Northeast Asia during DRAGON NE-Asia campaign  

NASA Astrophysics Data System (ADS)

Compared with the retrievals of aerosol optical depth (AOD) from polar orbiting satellites, the AOD retrievals from geostationary (GEO) satellites have a high temporal and spatial resolution. Because of this advantage of the geostationary satellite sensors, a better initial condition can be prepared for a better aerosol forecast or hindcast using the data from GEO sensors. We carried out a hindcast study over Northeast Asia, testing the effects of the improved initial conditions prepared from the AOD data from a geostationary satellite sensor. The AOD retrievals from the Geostationary Ocean Color Imager (GOCI) onboard the Communication, Ocean, and Meteorological Satellite (COMS) were used in this study, and the retrieved AOD data were assimilated with the AOD values calculated by the Community Multiscale Air Quality (CMAQ) Model. We assimilated the two data sets via an optimal interpolation (OI) technique, and the OI parameters of observation and modeling errors were calculated to minimize the variance of the differences between assimilated and AERONET AODs. The AERONET AODs were selected within the period of Distributed Regional Aerosol Gridded Observation Networks DRAGON North-East in Asia (DRAGON NE-ASIA) campaign, and were also used for comparison with the results of hindcast studies. The 6-hour hindcast results in several selected days using the GOCI-retrieved AOD data showed improved AOD distributions, compared with the AOD data from DRAGON-Northeast Asia AERONET sites. Also, using the GOCI and TERRA MODIS AOD retrievals, spatial coverage of satellite retrieval can be increased. 12-hour hindcast was also carried out using the combined GOCI-MODIS data sets.

Lee, S.; Song, C.; Park, M.; Park, R.; Kim, J.

2013-12-01

122

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

123

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

124

Improved monitoring of surface ozone by joint assimilation of geostationary satellite observations of ozone and CO  

NASA Astrophysics Data System (ADS)

Future geostationary satellite observations of tropospheric ozone aim to improve monitoring of surface ozone air quality. However, ozone retrievals from space have limited sensitivity in the lower troposphere (boundary layer). Data assimilation in a chemical transport model can propagate the information from the satellite observations to provide useful constraints on surface ozone. This may be aided by correlated satellite observations of carbon monoxide (CO), for which boundary layer sensitivity is easier to achieve. We examine the potential of concurrent geostationary observations of ozone and CO to improve constraints on surface ozone air quality through exploitation of ozone-CO model error correlations in a joint data assimilation framework. The hypothesis is that model transport errors diagnosed for CO provide information on corresponding errors in ozone. A paired-model analysis of ozone-CO error correlations in the boundary layer over North America in summer indicates positive error correlations in continental outflow but negative regional-scale error correlations over land, the latter reflecting opposite sensitivities of ozone and CO to boundary layer depth. Aircraft observations from the ICARTT campaign are consistent with this pattern but also indicate strong positive error correlations in fine-scale pollution plumes. We develop a joint ozone-CO data assimilation system and apply it to a regional-scale Observing System Simulation Experiment (OSSE) of the planned NASA GEO-CAPE geostationary mission over North America. We find substantial benefit from joint ozone-CO data assimilation in informing US ozone air quality if the instrument sensitivity for CO in the boundary layer is greater than that for ozone. A high-quality geostationary measurement of CO could potentially relax the requirements for boundary layer sensitivity of the ozone measurement. This is contingent on accurate characterization of ozone-CO error correlations. A finer-resolution data assimilation system resolving the urban scale would need to account for the change in sign of the ozone-CO error correlations between urban pollution plumes and the regional atmosphere.

Zoogman, Peter; Jacob, Daniel J.; Chance, Kelly; Worden, Helen M.; Edwards, David P.; Zhang, Lin

2014-02-01

125

Operational assessment of evapotranspiration from geostationary satellite data.  

NASA Astrophysics Data System (ADS)

EUMETSAT (http://www.eumetsat.int) has set up a network of decentralized meteorological satellite data processing centres named 'Satellite Application Facilities' (SAFs). These centres develop and achieve data products derived from European meteorological satellites. The 'Land-Surface-Analysis' SAF (LSA-SAF, http://landsaf.meteo.pt/), develops algorithms for the operational monitoring of land surface related variables. RMI participates to the LSA-SAF by developing an evapotranspiration (ET) product, ET being one of the most important water balance component [1]. As ET cannot be observed directly by remote sensing, it is assessed indirectly through modelling. The proposed model is based on a set of parameterizations of the SVAT scheme developed at ECMWF and it is adapted to be forced by real-time data derived from Meteosat Second Generation (MSG) satellites data. The SEVIRI instrument, on-board MSG, is designed to provide a wide area coverage and is able to monitor quick changing surface variables affected by cloudiness and diurnal cycle. It has a 3 km spatial resolution at sub-satellite point and a high observation repetition rate (15 min). The ET algorithm produces in near real time ET estimates at SEVIRI spatial resolution each 30 minutes. Results are generated since mid 2009 over four regions (Europe, North and South Africa and the Eastern part of South America) defined inside the MSG field of view. A daily product, available since end 2010, is also obtained through integration of the instantaneous estimates. Validation already carried out attests the robustness of the proposed algorithm, notably over Europe. Nevertheless, research will be pursued during coming years, looking for additional validation sites and evolving towards an improved combination of remote sensed observations and models. In this contribution we first present the LSA-SAF framework and we summarize how ET is deduced from MSG-SEVIRI data. In a second step, we compare LSA-SAF ET to ET products provided operationally by NWP models. Examples are specially illustrated for the location of a set of automatic weather stations in Belgium. LSA-SAF ET products characteristics are given in fine as well as information about accessibility of ET products to users. Reference: [1] N. Ghilain, A. Arboleda and F. Gellens-Meulenberghs, 2011, Hydrol. Earth Syst. Sci., doi:10.5194/hess-15-771-2011, 15, 771-786.

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

2012-04-01

126

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

E-print Network

of meteorological data and the proliferation of interactive systems The citations on the following pages follow the style of the J 1 f A~li d M~tl designed to display and compare fields of satellite, digital radar, and conventional surface and upper-air data... on TIROS 9 imagery, shipborne and shore- based radar data, and surface and upper-air data. Yonder Haar (1969) employed data from the geostationary satel- lites ATS 1 (Applications Technology Satellite 1) and ATS 3 in a study of reflected radiance...

Henderson, Rodney Stuart

2012-06-07

127

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

NASA Astrophysics Data System (ADS)

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

Cutrim, Elen Maria Camara

128

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

129

Orbit control of SPOT satellites  

NASA Astrophysics Data System (ADS)

The SPOT system has been operational since the February 22nd, 1986, SPOT 1 launch date. SPOT 2, the second satellite, was put in orbit on February 21st, 1990, and station acquisition of SPOT 3, the last first generation satellite, was successfully performed after the September 26th, 1993 Ariane launch. Now, three satellites are in orbit, and their relative positions depend on the station keeping requirements specified for each one. Only SPOT 2 and SPOT 3 products are presently commercialized, SPOT 1 being kept in standby. The purpose of this document is to explain the flight dynamics aspects of the system. It synthesizes the specifications related to this field, and recalls specific data resulting from the mission analysis. Described in detail are the station acquisition (referring to the operational results of SPOT 3 launch), launch phase, description of the operations, station acquisition, maneuvers strategy, definition of the parameters monitored for station keeping, automatic management of maneuvers, and relative deviation of the 3 satellites.

Darrigan, Christian; Dulot, Jean-Louis; Forcioli, Dominique; Micheau, Pascal

130

Long-Term Prediction of Satellite Orbit Using Analytical Method  

NASA Astrophysics Data System (ADS)

A long-term prediction algorithm of geostationary orbit was developed using the analytical method. The perturbation force models include geopotential upto fifth order and degree and luni-solar gravitation, and solar radiation pressure. All of the perturbation effects were analyzed by secular variations, short-period variations, and long-period variations for equinoctial elements such as the semi-major axis, eccentricity vector, inclination vector, and mean longitude of the satellite. Result of the analytical orbit propagator was compared with that of the cowell orbit propagator for the KOREASAT. The comparison indicated that the analytical solution could predict the semi-major axis with an accuarcy of better than ~35meters over a period of 3 month.

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

1997-12-01

131

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

132

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

133

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

134

Connection between the discrete auroral structures drifting equatorward during the substorm expansion phase and the energetic particle injections at the geostationary orbit  

NASA Astrophysics Data System (ADS)

The formation of an auroral bulge with a bright dynamical arc at its polar boundary is one of the main manifestations of the magnetospheric substorm expansion phase at the ionospheric level. At the same time, the region of discrete aurora broadens not only polewards but equatorwards as well. The discrete forms of auroras moving equatorwards form a dynamical equatorial boundary of the auroral bulge shifting together with them. The paper presents a spatial-time comparison of the drifting discrete auroras to the injection of energetic particles at the geostationary orbit. It is shown that bursts in the fluxes of energetic particles at the LANL geostationary satellites located in the same sector of MLT correspond to the majority of drifting discrete auroral structures observed by the all-sky camera. In the cases when the bursts in the fluxes are absent, the minimum latitude reached by the auroral structures at the equatorward drift is higher than the ionospheric projection of the geostationary orbit. A possible relation of the drifting discrete auroras to the plasma stream jets in the plasma sheet is discussed.

Dmitrieva, N. P.; Beloshkurskaya, M. M.; Kornilova, T. A.; Kornilov, I. A.

2014-07-01

135

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

136

Orbit determination for ISRO satellite missions  

Microsoft Academic Search

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

Ch. Sreehari Rao; S. K. Sinha

1985-01-01

137

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

138

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

139

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

140

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

141

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

142

Next generation Geostationary Operational Environmental Satellite: GOES-R, the United States' advanced weather sentinel  

NASA Astrophysics Data System (ADS)

The Geostationary Operational Environmental Satellite R-series (GOES-R) is the follow-on to the existing GOES system, completing a transition from 1980's technology to state-of-the-art. The product of a collaborative development effort between NOAA, NASA, DOC and industry, the first GOES-R satellite is planned to be launched in April 2015 with readiness to fully replace the heritage GOES constellation in 2017. This next-generation system will continue as the United States' weather sentinel for forecasting hurricanes, severe storms, and flash floods while providing information about air quality, winds, sea surface temperature, and space weather. It will provide advanced capabilities by providing five times more spectral information, temporal coverage six times faster than the current system, and 50% higher spatial resolution. The heart of the GOES-R system is the ABI instrument, a sixteen-channel imager with six visible channels and 10 infrared channels. The GLM instrument will be the first geostationary sensor to detect and monitor lightning strikes. GOES-R also includes several space environment sensors that will increase the capability to monitor and predict solar flare activity. Additionally, GOES-R will continue to provide heritage search and rescue capabilities, a data collection system, and other direct readout capabilities.

Bloom, Hal J.

2009-08-01

143

Time series modeling and large scale global solar radiation forecasting from geostationary satellites data  

E-print Network

When a territory is poorly instrumented, geostationary satellites data can be useful to predict global solar radiation. In this paper, we use geostationary satellites data to generate 2-D time series of solar radiation for the next hour. The results presented in this paper relate to a particular territory, the Corsica Island, but as data used are available for the entire surface of the globe, our method can be easily exploited to another place. Indeed 2-D hourly time series are extracted from the HelioClim-3 surface solar irradiation database treated by the Heliosat-2 model. Each point of the map have been used as training data and inputs of artificial neural networks (ANN) and as inputs for two persistence models (scaled or not). Comparisons between these models and clear sky estimations were proceeded to evaluate the performances. We found a normalized root mean square error (nRMSE) close to 16.5% for the two best predictors (scaled persistence and ANN) equivalent to 35-45% related to ground measurements. F...

Voyant, Cyril; Muselli, Marc; Paoli, Christophe; Nivet, Marie Laure

2014-01-01

144

Communication by Polar-Orbit Satellite Relay  

Microsoft Academic Search

Aircraft on transpolar flights do not have highly reliable noise-free communications. By the use of polar-orbiting satellite repeaters, UHF communications can be utilized. Active, wideband repeaters are proposed in the satellite, using equipment similar to existing hardware. A system is discussed for a 5000-mile altitude satellite orbit and a 3500-mile ground distance separation. Complete system parameters are described. The satellite

W. Hagan

1960-01-01

145

Precise orbit determination for CAPS project  

Microsoft Academic Search

The Chinese Area Positioning System (CAPS) is a new type of satellite navigation systems. The geostationary satellites for normal communication with 2 or 3 sets of inclined geostationary orbit (GEO) satellites are employed to construct a satellite navigation system. The navigation signals are constructed and disseminated on the ground, and the satellites only transfer the signals to the ground by

Wu Wenjun; Li Zhigang; Chen Xuan; Lei Hui; Yang Xuhai; Feng Chugang

2010-01-01

146

System Approach to the Forecast of Electron Fluxes iAT Geostationary Orbit  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

147

Orbital subcycles for Earth remote sensing satellites  

Microsoft Academic Search

In this paper 1 review the reasons why it is desirable to place a remote-sensing satellite into an orbit which periodically repeats its path. Such exactly-repeating orbits are often used for Earth remote-sensing satellites, but the most appropriate orbit depends upon the likely application of the data. If they are to be used to study a rapidly changing phenomenon a

W. G. REES

1992-01-01

148

ERAD 2012 -THE SEVENTH EUROPEAN CONFERENCE ON RADAR IN METEOROLOGY AND HYDROLOGY On the opportunistic use of geostationary satellite  

E-print Network

On the opportunistic use of geostationary satellite signals to estimate rain rate in the purpose of radar calibration.barthes@latmos.ipsl.fr, cecile.mallet@latmos.ipsl.fr 15 April 2012 Rain gauge networks are often used for radar calibration al. (2006) and Leijnse et al. (2007) have shown that the path-integrated rain rate can be estimated

Boyer, Edmond

149

Accepted for Remote Sensing of Environment, October 20081 Sea surface temperature from a geostationary satellite by optimal2  

E-print Network

a geostationary satellite by optimal2 estimation3 4 C. J. Merchanta,* , P. Le Borgneb , H. Roquetb and A fields and a fast radiative transfer model. Bias correction of the simulated20 brightness temperatures of simulations minus observations over a time period of 20 days and spatial scale of 2.5° in22 latitude

Merchant, Chris

150

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

151

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

152

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

153

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

154

Fire Monitoring from the New Generation of US Polar and Geostationary Satellites  

NASA Astrophysics Data System (ADS)

Sensors on the new generation of US operational environmental satellites will provide measurements suitable for active fire detection and characterization. The NPOESS Preparatory Project (NPP) satellite, launched on October 28, 2011, carries the Visible Infrared Imager Radiometer Suite (VIIRS), which is expected to continue the active fire data record from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Earth Observing System Terra and Aqua Satellites. Early evaluation of the VIIRS active fire product, including comparison to near-simultaneous MODIS data, is underway. The new generation of Geostationary Operational Environmental Satellite (GOES) series, starting with GOES-R to be launched in 2015, will carry the Advanced Baseline Imager (ABI), providing higher spatial and temporal resolution than the current GOES imager. The ABI will also include a dedicated band to provide radiance observations over a wider dynamic range to detect and characterize hot targets. In this presentation we discuss details of the monitoring capabilities from both VIIRS and ABI and the current status of the corresponding algorithm development and testing efforts. An integral part of this activity is explicit product validation, utilizing high resolution satellite and airborne imagery as reference data. The new capabilities also represent challenges to establish continuity with data records from heritage missions, and to coordinate compatible international missions towards a global multi-platform fire monitoring system. These objectives are pursued by the Fire Mapping and Monitoring Implementation Team of the Global Observation of Forest and Land Cover Dynamics (GOFC-GOLD) program, which also provides coordinated contribution to relevant initiatives by the Committee on Earth Observation Satellites (CEOS), the Coordination Group for Meteorological Satellites (CGMS) and the Global Climate Observing System (GCOS).

Csiszar, I.; Justice, C. O.; Prins, E.; Schroeder, W.; Schmidt, C.; Giglio, L.

2012-04-01

155

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

156

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

Federal Register 2010, 2011, 2012, 2013

...This industry comprises establishments primarily engaged in operating...Telecommunications ``comprises establishments primarily engaged in providing...telecommunications services to other establishments in the telecommunications...

2010-04-05

157

Hurricane Katrina Satellite Imagery  

NSDL National Science Digital Library

This page provides access to a good number of satellite images of Hurricane Katrina taken by polar orbiting and geostationary satellites operated by NOAA. High resolution images are available on the site.

National Environmental Satellite, Data, and Information Service

158

Flight Paths of Orbiting Satellites  

NSDL National Science Digital Library

This is an activity to help students visualize the relationship of motion, time and space as it relates to objects orbiting the earth. They will be able to track the path of an orbiting object on a globe, plot the path of an orbiting object on a flat world map, and explain that an object orbiting earth on a plane will produce a flight path which appears as wavy lines on the earths surface.

159

Effect of the high-order resonances on the orbital evolution of objects near geostationary orbit  

NASA Astrophysics Data System (ADS)

The area-to-mass ratio of high-orbit space objects is estimated on the basis of positional observations from the SBG telescope at the Kourovka astronomical observatory of the Ural Federal University. The properties of regions where high-order resonances are located are analyzed. The position and sizes of the resonance zones depending on the area-to-mass ratio of objects are determined on the basis of numerical modeling. It is shown that a system transits through the high-order resonances due to secular perturbations of the semimajor axis under the Poynting-Robertson effect. The high-order resonances weakly influence the formation of the stochastic trajectories. The stochastic properties are mostly manifested in evolution of the semimajor axis of the orbit.

Kuznetsov, E. D.; Zakharova, P. E.; Glamazda, D. V.; Kudryavtsev, S. O.

2014-11-01

160

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

SciTech Connect

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

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

1995-01-01

161

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.

162

GeoSTAR: Developing a Microwave Sounder for Geostationary Weather Satellites  

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

163

Extrapolation of orbits  

Microsoft Academic Search

The use of analytic theory, numerical integration, or a mixed method in the extrapolation of a spacecraft orbit is shown to depend on mission requirements. Parameters to be extrapolated for the ARGOS satellite system, for SPOT satellite, DZB satellite, and for geostationary satellites are among examples cited. Orbit extrapolation for SKYLAB reentry is also covered. Analytic methods include integration of

N. Borderies

1980-01-01

164

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

Code of Federal Regulations, 2010 CFR

...service. 25.278 Section 25.278 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.278 Additional coordination obligation...

2010-10-01

165

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

166

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

167

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

SciTech Connect

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

Yamamoto, Tetsuya T.; Miyoshi, Y., E-mail: tyamamot@stelab.nagoya-u.ac.jp [Solar-Terrestrial Environment Laboratory, Nagoya University, Aichi (Japan)

2013-10-01

168

Orbital Stability of the Uranian Satellite System  

Microsoft Academic Search

We have numerically integrated approximately 500 systems of mutually gravitating bodies which were based on subsets of the uranian satellite system. In each run within a set, the satellite masses were initially multiplied by a common mass enhancement factormf. The simulations were terminated at the “crossing time,”tc, when mutual perturbations excited eccentricities sufficiently large for orbits of a pair of

Martin J. Duncan; Jack J. Lissauer

1997-01-01

169

The orbits of the satellites of Neptune  

Microsoft Academic Search

This article presents the results of a fit of numerically integrated Neptunian satellite orbits to earth-based astrometric observations and early Voyager spacecraft observations. Ephemerides based on these orbits were used by the Voyager project as the final pre-encounter ephemerides. As a by-product of the orbit fits, estimates of the Neptune mass, the second zonal harmonic of Neptune, and the pole

R. A. Jacobson

1990-01-01

170

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

171

Orbital operation for large automated satellites  

NASA Technical Reports Server (NTRS)

Orbital operations concepts for the shuttle launched Large Automated Satellites (LAS) are discussed. It includes the orbital operations elements and the major options for accomplishing each element. This study is based on the preliminary payload information available in Level I and II documents and on orbital operations methods used on past programs, both manned and unmanned. It includes a definition of detailed trade studies which need to be performed as satellite design details and organization responsibilities are defined. The major objectives of this study were to define operational methods and requirements for the long duration LAS missions which are effective and primarily economical to implement.

Lusk, J. L.; Biro, V.

1974-01-01

172

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

173

Weather, Climate and Air quality data acquired from quasi-geostationary viewing of high latitudes using highly elliptical orbits  

NASA Astrophysics Data System (ADS)

The Arctic multi-year ice cover is disappearing more rapidly than climate models estimate and the Arctic climate is also changing. 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 multifaceted need to monitor the polar region. A number of Canadian government departments, led by the Canadian Space Agency (CSA), are proposing the Polar Communications and Weather (PCW) mission to provide improved communications and critically important meteorological and air quality information for the Arctic using an operational meteorological imager. Two satellites in highly eccentric orbits with apogees at ~ 40,000 km over the Arctic would provide quasi-geostationary viewing over the Arctic with 24-7 coverage in the IR and measure solar reflected light in the summertime. The planned operational meteorological instrument is a 21-channel spectral imager with UV, visible, NIR and MIR channels similar to MODIS and ABI. This presentation will focus on the PHEOS-WCA (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 field of regard ~ 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 <2 hours. The characteristics of the PHEOS-WCA measurements will be described, along with the expected retrieval accuracy of various measured constituents. The quasi-stationary viewing will provide the ability to measure the diurnal behavior of atmospheric properties under the satellites and the ability to provide data for weather forecasting and also air quality data assimilation. One of the important goals for PHEMOS-FTS is to measure changes in CO2 and CH4 throughout the day-lit hours in the NIR near apogee. In this presentation we will outline the scientific objectives, status of retrieval algorithms and also the viewing geometry necessary with two satellites.

McElroy, C. T.; Sioris, C. E.; Walker, K. A.; Buijs, H.; Trichtchenko, A.; Garand, L.; Nassar, R.; Martin, R.; Bergeron, M.; O'Neill, N. T.

2013-12-01

174

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

NASA Astrophysics Data System (ADS)

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

Nusinov, Anatoliy; Kazachevskaya, Tamara; Gonjukh, David

175

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

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

176

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

177

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

178

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

PubMed Central

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

179

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

180

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

Microsoft Academic Search

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

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

2005-01-01

181

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

182

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

183

Calculation of electromagnetic fields induced on a geostationary satellite by an electrostatic discharge  

NASA Astrophysics Data System (ADS)

The electromagnetic response of an orbiting satellite to an electrostatic discharge is compared to that of the same object subjected (in a susceptibility test) to an injection current. In the absence of actual data, the comparison was performed on the basis of two numerical simulations: one using the GEODE particle code for the orbiting case, and the other using the ALICE code for a representative injection configuration. It is found that the evolution of the electromagnetic fields is controlled in particular by the particle emission rhythm, giving rise to an ejection flux 'slit' whose rise time is about several tens of nanoseconds.

Froger, E.; Marque, J. P.

184

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

185

Orbit Design of Earth-Observation Satellite  

NASA Astrophysics Data System (ADS)

The purpose of this study is to design a reliable orbit for a medium-resolution scientific satellite to observe Earth for developmental issues such as water resources, agricultural, and industrial. To meet this objective this study firstly, defines the mission, secondly, determines mission constraints, thirdly, design the attitude and orbit control system. As for the observation requirements, and the revisit time are provided as a function of the orbital parameters. Initial orbital parameters are obtained by optimal analysis between observation characteristics and attitude and orbit maintenance costs. Long term station-keeping strategies will be provided for the proposed solutions. Impulsive control will be investigated to provide a reliable and affordable attitude and orbit control system.

Owis, Ashraf

186

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

187

Estimating Density Using Precision Satellite Orbits from Multiple Satellites  

NASA Astrophysics Data System (ADS)

This article examines atmospheric densities estimated using precision orbit ephemerides (POE) from several satellites including CHAMP, GRACE, and TerraSAR-X. The results of the calibration of atmospheric densities along the CHAMP and GRACE-A orbits derived using POEs with those derived using accelerometers are compared for various levels of solar and geomagnetic activity to examine the consistency in calibration between the two satellites. Densities from CHAMP and GRACE are compared when GRACE is orbiting nearly directly above CHAMP. In addition, the densities derived simultaneously from CHAMP, GRACE-A, and TerraSAR-X are compared to the Jacchia 1971 and NRLMSISE-00 model densities to observe altitude effects and consistency in the offsets from the empirical models among all three satellites.

McLaughlin, Craig A.; Lechtenberg, Travis; Fattig, Eric; Krishna, Dhaval Mysore

2012-06-01

188

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

NASA Astrophysics Data System (ADS)

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

Kurino, T.

2012-12-01

189

Precise Orbit Determination for Altimeter Satellites  

Microsoft Academic Search

Orbit error remains a critical component in the error budget for all radar altimeter missions. This paper describes the ongoing work at GSFC to improve orbits for three radar altimeter satellites: TOPEX\\/POSEIDON (T\\/P), Jason, and Geosat Follow-On (GFO). T\\/P has demonstrated that, the time variation of ocean topography can be determined with an accuracy of a few centimeters, thanks to

N. P. Zelensky; S. B. Luthcke; D. D. Rowlands; F. G. Lemoine; B. B. Beckley; Y. Wang; D. S. Chinn

2002-01-01

190

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

191

Cloud-Top Height Estimation by Geostationary Satellite Split-Window Measurements using CloudSat Measurements  

NASA Astrophysics Data System (ADS)

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

Hamada, A.; Nishi, N.

2009-12-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

193

Five Special Types of Orbits Around Mars  

Microsoft Academic Search

The abstract is additional with repect to the paper published in JGCD. Ordinary Earth satellites are usually placed into five categories of special orbits: sun-synchronous orbits, orbits at the critical inclination, frozen orbits, repeating ground track orbits, and geostationary orbits. This paper investigates their counterparts around Mars and examines the basic nature of these orbits, which are of special interest

Xiaodong Liu; Hexi Baoyin; Xingrui Ma

2011-01-01

194

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

195

Stability of satellite orbits around nonspherical planets  

Microsoft Academic Search

Dynamical systems associated to a Newtonian-type potential plus a perturbing potential containing a small real parameter model a large class of concrete astronomical situations, among which satellite orbits have a place of choice. We investigate such models using a combination between block-diagonalization technique and the usual reduction procedure. Within the so-called \\

Vasile Mioc; Magda Stavinschi

2004-01-01

196

Preliminary orbit determination for lunar satellites.  

NASA Technical Reports Server (NTRS)

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

Lancaster, E. R.

1973-01-01

197

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

Microsoft Academic Search

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

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

2010-01-01

198

Galilean satellite tour orbit determination assessment  

NASA Technical Reports Server (NTRS)

Results are given which demonstrate the ability of the orbit determination system to satisfy accuracy requirements in support of the Galileo Project's planned tour of Jupiter's satellites. The results are derived through the application of mission operation strategies and assumptions. It is shown that the achievement of the requisite orbit determination accuracies is predicated on the availability of optical navigation data. It is further demonstrated that the unavailability of tour optical navigation data yields not only degraded orbit determination accuracies which fail to meet propellant budget and science instrument pointing requirements, but also produces, for the planned 200 km flyby of Europa, an approximate 0.02 risk of having the spacecraft collide with the satellite.

Moultrie, B.; Kenyon, P. R.; Kechichian, J. A.; Davis, R. P.; Nicholson, F. T.

1987-01-01

199

History of on-orbit satellite fragmentations  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

200

Online Visualization and Analysis of Merged Global Geostationary Satellite Infrared Dataset  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

201

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

202

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

203

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

204

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

205

Acquisition and Re-orbiting of GEO Satellites Using Low Thrust Propulsion  

NASA Astrophysics Data System (ADS)

The Plasma Laboratory of the University of Brasilia is developing a special type of plasma thruster, a P-HALL, which is now in the second prototype. Plasma thrusters generate low thrust propulsion, but with high specific impulse, and they can work continuously for long periods of time. In the present work we explore three different types of orbital missions needs. 1) Transference between two circular orbits, from LEO to GEO. We analysed a set of satellite maneuvers, and compared the use continuous and pulsed propulsion to achieve the transference. Using the data obtained in the laboratory, we simulated several possibilities to transfer a satellites from an orbit of 700km altitude to a geostationary position. Using continuous thruster, we mapped several values of the maneuver time, the satellite mass, the mass ejection and the impulse. The results show that, for example, it is possible to achieve the maneuver using 150 kg of propellant taking about 200 days. 2) Transference through circularization of the orbit. Considering an eccentric orbit whose pericenter has altitude of 700km and apocenter close to a GEO, it is proposed to circularize the orbit such that the final orbit become GEO. The approach adopted is to turn on the thruster along an arc, ??, at each pericenter passage. The results are found in terms of the whole transference time as a function of ??. 3) Re-orbiting GEO satellites. In this case the goal is to place a GEO satellite at a higher orbit to release its current position from occupation. The procedure adopted was to turn on the thruster along two fixed size arcs, ??, 180 degrees apart from each other. The results are found in terms of the fuel consumption as a function of ??.

Mourão, Décio; Ferreira, Jose Leonardo; Winter, Othon; Silva Moraes, Brunno; Giuliatti Winter, Silvia Maria

206

Orbits of the six new satellites of Neptune  

SciTech Connect

Orbital elements are presented for the six small satellites of Neptune, 1989N1 through 1989N6, discovered by Voyager 2. Details of the image and orbit analyses are examined. The solution for the orbits of the six satellites is presented in terms of geometric classical Keplerian elements. All six are in nearly circular direct orbits; most of the satellites have low inclinations, except the innermost, 1989N6, which is inclined at 4.7 deg to Neptune's equator. 21 refs.

Owen, W.M., Jr.; Vaughan, R.M.; Synnott, S.P. (JPL, Pasadena, CA (USA))

1991-04-01

207

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

208

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

209

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

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

210

Footprint handover rerouting protocol for low Earth orbit satellite networks  

Microsoft Academic Search

Low Earth Orbit (LEO) satellite networks will be an integral part of the next generation telecommunications infrastructures. In a LEO satellite network, satellites and their individual coverage areas move relative to a fixed observer on Earth. To ensure that ongoing calls are not disrupted as a result of satellite movement, calls should be transferred or handed over to new satellites.

Hüseyin Uzunalioglu; Ian F. Akyildiz; Yelena Yesha; Wei Yen

1999-01-01

211

COSPAS-SARSAT Satellite Orbit Predictor Volume 10  

NASA Technical Reports Server (NTRS)

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

Friedman, Morton L.

1987-01-01

212

COSPAS-SARSAT Satellite Orbit Predictor. Volume 3  

NASA Technical Reports Server (NTRS)

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

Friedman, Morton L.; Garrett, James

1984-01-01

213

COSPAS-SARSAT Satellite Orbit Predictor, Vol 4  

NASA Technical Reports Server (NTRS)

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

Friedman, Morton L.; Garrett, James, Major

1984-01-01

214

Mars: The dynamics of orbiting satellites and gravity model development  

Microsoft Academic Search

Three major questions are addressed: (1) what is the sensitivity of satellites to the Mars gravity field?; (2) can the range measurements to the Viking Orbiters be used to improve the solutions for the Mars gravity field?; and (3) what improvements can be made to the force models for spacecraft in orbit about Mars? Mars orbiting satellites, including the Mariner

Frank George Rodrigue Lemoine

1992-01-01

215

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

216

Estimate of Solar Maximum using the 1-8 \\AA$\\,$Geostationary Operational Environmental Satellites X-ray Measurements  

E-print Network

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

Winter, L M

2014-01-01

217

Measurement of total electron content with a geostationary satellite during the solar eclipse of March 7, 1970.  

NASA Technical Reports Server (NTRS)

This note deals with the measurement of the total electron content of the ionosphere at the Goddard Space Flight Center, looking towards the geostationary satellite ATS 3 during the solar eclipse of Mar. 7, 1970. Obscuration at this site was nearly total. Faraday rotation was measured with a stationary circularly polarized antenna and a dual-channel phase-lock receiver tuned to 137.350 MHz. By comparing the electrical phase of the two opposite circularly polarized components, a continuous chart recording was made of Faraday rotation vs local time. A depletion of about 25% in electron content was observed from first contact to the time of minimum electron content. The time variations of the electron content during the eclipse are briefly examined in the light of current theories of ionospheric processes.

Rangaswamy, S.; Schmid, P. E.

1971-01-01

218

Estimate of Solar Maximum Using the 1-8 Å Geostationary Operational Environmental Satellites X-Ray Measurements  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

219

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

E-print Network

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

Wadsworth, Brandon Scott

2012-06-07

220

Jupiter orbiter lifetime: The hazard of Galilean satellite collision  

NASA Technical Reports Server (NTRS)

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

Friedlander, A. L.

1975-01-01

221

Orbit determination for the GOCE satellite  

NASA Astrophysics Data System (ADS)

Precise Orbit Determination (POD) for the Gravity field and steady-state Ocean Circulation Explorer (GOCE), the first core explorer mission by the European Space Agency (ESA), forms an integrated part of the so-called High-Level Processing Facility (HPF). Two POD chains have been set up referred to as quick-look Rapid and Precise Science Orbit determination or RSO and PSO, respectively. These chains make use of different software systems and have latencies of 1 day and 2 weeks, respectively, after tracking data availability. The RSO and PSO solutions have to meet a 3-dimensional (3D) position precision requirement of 50 cm and a few cm, respectively. The tracking data will be collected by the new Lagrange GPS receiver and the predicted characteristics of this receiver have been taken into account during the implementation phase of the two chains. This paper provides an overview of the two POD processing chains and includes a description of the required input, auxiliary and output products. Both chains have been tested with real data from the German CHAMP and the EUMETSAT MetOp satellites, which carry a BlackJack and GRAS GPS receiver, respectively. The consistency between CHAMP and MetOp orbit solutions computed with the final implementation of the different chains was found to be better than 10 cm in 3D position when use is made of high-quality GPS ephemeris and clock solutions. In addition, test results with data from a GOCE End-to-End (E2E) simulator which incorporates a model of the Lagrange receiver have been included. The differences between all orbit solutions was found to be of the order of a few cm for all directions. The precision requirements for the two chains were thus not only met with E2E simulated data, but also with real data from CHAMP and MetOp.

Visser, P. N. A. M.; van den Ijssel, J.; van Helleputte, T.; Bock, H.; Jäggi, A.; Beutler, G.; Švehla, D.; Hugentobler, U.; Heinze, M.

2009-03-01

222

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

SciTech Connect

This paper describes the results from a collaborative study between the European Space Operations Center, the European Organization for the Exploitation of Meteorological Satellites, the National Oceanic and Atmospheric Administration, and the Cooperative Institute for Meterological Satellite Studies investigating the relationship between satellite-derived monthly mean fields of wind and humidity in the upper troposphere for March 1994. Three geostationary meteorological satellites GOES-7, Meteosat-3, and Meteosat-5 are used to cover an area from roughly 160{degrees}W to 50{degrees}E. The wind fields are derived from tracking features in successive images of upper-tropospheric water vapor (WV) as depicted in the 6.5-{mu} absorption band. The upper-tropospheric relative humidity (UTH) is inferred from measured water vapor radiances with a physical retrieval scheme based on radiative forward calculations. Quantitative information on large-scale circulation patterns in the upper troposphere is possible with the dense spatial coverage of the WV wind vectors. The monthly mean wind field is used to estimate the large-scale divergence; values range between about -5 x 10{sup -6} and 5 x 10{sup -6} sec{sup -1} when averaged over a scale length of about 1000-2000 km. The spatial patterns of the UTH field and the divergence of the wind field closely resemble one another, suggesting that UTH patterns are principally determined by the large-scale circulation. Since the upper-tropospheric humidity absorbs upwelling radiation from lower-tropospheric levels and therefore contributes significantly to the atmospheric greenhouse effect, this work implies that studies on the climate relevance of water vapor should include three-dimensional modeling of the atmospheric dynamics. The fields of UTH and WV winds are useful parameters for a climate-monitoring system based on satellite data. 21 refs., 5 figs.

Schmetz, J. [European Organization for the Exploitation of Meteorological Satellites, Darmstadt (Germany)] [European Organization for the Exploitation of Meteorological Satellites, Darmstadt (Germany); Menzel, W.P.; Hayden, C. [NOAA/NESDIS, Madison, WI (United States)] [and others] [NOAA/NESDIS, Madison, WI (United States); and others

1995-09-01

223

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

224

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

225

A system for autonomous navigation and attitude determination in geostationary orbit  

Microsoft Academic Search

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

P. Maute; O. Defonte

1990-01-01

226

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

227

Satellite orbital conjunction reports assessing threatening encounters in space (SOCRATES)  

NASA Astrophysics Data System (ADS)

While many satellite operators are aware of the possibility of a collision between their satellite and another object in earth orbit, most seem unaware of the frequency of near misses occurring each day. Until recently, no service existed to advise satellite operators of an impending conjunction of a satellite payload with another satellite, putting the responsibility for determining these occurrences squarely on the satellite operator's shoulders. This problem has been further confounded by the lack of a timely, comprehensive data set of satellite orbital element sets and computationally efficient tools to provide predictions using industry-standard software. As a result, hundreds of conjunctions within 1 km occur each week, with little or no intervention, putting billions of dollars of space hardware at risk, along with their associated missions. As a service to the satellite operator community, the Center for Space Standards & Innovation (CSSI) offers SOCRATES-Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space. Twice each day, CSSI runs a list of all satellite payloads on orbit against a list of all objects on orbit using the catalog of all unclassified NORAD two-line element sets to look for conjunctions over the next seven days. The runs are made using STK/CAT-Satellite Tool Kit's Conjunction Analysis Tools-together with the NORAD SGP4 propagator in STK. This paper will discuss how SOCRATES works and how it can help satellite operators avoid undesired close approaches through advanced mission planning.

Kelso, T. S.; Alfano, S.

2006-05-01

228

Link Analysis of a Telecommunication System on Earth, in Geostationary Orbit, and at the Moon: Atmospheric Attenuation and Noise Temperature Effects  

Microsoft Academic Search

Two uncertain factors affecting a telecommunication system's performance are effective antenna gain and system noise temperature. For an Earth-geostationary satellite-Moon system, they are attributed to the atmospheric attenuation and ra- diation. In the super-high frequency band, the attenuations are mostly weather re- lated and have the same values for both upward- and downward-propagating signals, while brightness temperatures have different effects

C. Ho; A. Kantak; S. Slobin; D. Morabito

229

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

230

Analysing NDVI for the African continent using the geostationary meteosat second generation SEVIRI sensor  

Microsoft Academic Search

This study presents first results on Normalized Difference Vegetation Index (NDVI), from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) sensor onboard the geostationary satellite Meteosat Second Generation (MSG) covering the African continent. With a temporal resolution of 15 min MSG offers complementary information for NDVI monitoring compared to vegetation monitoring based on polar orbiting satellites. The improved temporal resolution

Rasmus Fensholt; Inge Sandholt; Simon Stisen; Compton Tucker

2006-01-01

231

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

232

Timing Synchronization in MF-TDMA Systems for Geostationary Satellites[Topics in Radio Communications  

Microsoft Academic Search

The most expensive costs in satellite communication are incurred by the space segment. Therefore, effort should be focused on the efficient use of this resource. One aspect is the optimization of the physical layer, to approach the Shannon limit of channel capacity. In IP-based networks, communication between arbitrary terminals can be established, which must hold for IP-based satellite networks as

Wolfgang Kogler; Harald Schlemmer; Otto Koudelka

2007-01-01

233

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

234

Precise science orbits for the Swarm satellite constellation  

NASA Astrophysics Data System (ADS)

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

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

235

Modeling GPS satellite attitude variation for precise orbit determination  

Microsoft Academic Search

High precision geodetic application of the Global Positioning System (GPS) require highly precise ephemerides of the GPS satellites. An accurate model for the non-gravitational forces on the GPS satellites is a key to high quality GPS orbit determination, especially in long arcs. In this paper the effect of the satellite solar panel orientation error is investigated. These effects are approximated

D. Kuang; H. J. Rim; B. E. Schutz; P. A. M. Abusali

1996-01-01

236

Geostationary satellite position determination for common-view two-way time transfer measurements  

NASA Technical Reports Server (NTRS)

In common-view two-way time transfer, each earth station receives an unwanted return signal from its own transmission as well as the desired signal from the other earth station. National Institute of Standards and Technology (NIST), the National Research Council (NRC), and the U.S. Naval Observatory (USNO) have been cooperating in a three-corner common-view two-way time transfer experiment. Some systematic effects are known to depend on the position of the satellite (Sagnac effect and the cross-correlation pulling of the pseudo-random codes). A method is presented for deriving accurate satellite ranges from each of three stations doing common-view two-way satellite time transfer measurements, when one (and only one) station also takes ranging measurements on its 'unwanted return signal' for a brief period. The method is applied to determine the variations in position of the satellite used over the course of the NIST/NRC/USNO SBS-3 experiment, with ranging data taken at NRC, where no additional hardware was required to automate the process. The fit and extrapolation which are employed in this method have an estimated precision of 2 m. If the delays of SBS-3 satellite KU band transponder and earth station equipment were measured accurately as well as the tropospheric refractions were well modeled and corrected, we would expect a ranging accuracy of 2.5 m and satellite positioning accuracy would be 200 m (latitude) 50 m (longitude) and 20 m (height above ellipsoid).

Zhuang, Qixiang; Douglas, Robert J.

1992-01-01

237

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

238

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

239

In-orbit storage of SPOT 1 satellite  

NASA Astrophysics Data System (ADS)

SPOT sun-synchronous remote sensing satellites have been operated by CNES since February 1986. Today, the SPOT mission and control center operates SPOT 1, SPOT 2 and SPOT 3. The eight-year-old SPOT 1 satellite is still able to transmit in real time the images acquired. In 1992, CNES decided to store it in orbit as a back-up satellite in case of major failure on SPOT 2 or SPOT 3. The storage is based on an entire in-orbit autonomy of the satellite for orbit and attitude control, and a reduced use of ground equipment. With two visibilities per day, used only for telemetry monitoring and orbit computation, the ground control workload decreases to a low cost operation. Obviously, in case of satellite anomaly, the mission and control center can be reactivated in order to repair the failure.

Pacholczyk, Philippe

240

HY-2A altimetry satellite GPS orbits processing and performances  

NASA Astrophysics Data System (ADS)

The Chinese HY-2A altimetry satellite is on the mission orbit since 1st october 2011. This satellite uses a Doris receiver (French cooperation), a GPS receiver and a SLR retro-reflector for the precise orbit determination. The GPS is a dual frequency semi-codeless receiver. Precise orbits are computed at CNES on the basis of 7 days arcs since the beginning of the mission (repeat cycle is 14 days). This presentation describes the current processing performed at CNES for this satellite. The GPS only orbits perform very well and are compared with the Doris only orbits (floating ambiguity resolution, as for Jason 1 and 2). SLR measurements are also available at ILRS, and allow an external validation of the actual radial orbit performance. This talk adresses the current status of POE solutions and the prospects for improvement based on the preliminary analysis of the tracking data.

Mercier, F.; Houry, S.; Couhert, A.; Cerri, L.

2012-04-01

241

Potential for calibration of geostationary meteorological satellite imagers using the Moon  

E-print Network

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 histories for these instruments, regardless of their current operational status. Keywords: On

Christian, Eric

242

Estimation of surface turbulent heat fluxes via variational assimilation of sequences of land surface temperatures from Geostationary Operational Environmental Satellites  

NASA Astrophysics Data System (ADS)

a number of studies have focused on estimating surface turbulent heat fluxes via assimilation of sequences of land surface temperature (LST) observations into variational data assimilation (VDA) schemes. Using the full heat diffusion equation as a constraint, the surface energy balance equation can be solved via assimilation of sequences of LST within a VDA framework. However, the VDA methods have been tested only in limited field sites that span only a few climate and land use types. Hence, in this study, combined-source (CS) and dual-source (DS) VDA schemes are tested extensively over six FluxNet sites with different vegetation covers (grassland, cropland, and forest) and climate conditions. The CS model groups the soil and canopy together as a single source and does not consider their different contributions to the total turbulent heat fluxes, while the DS model considers them to be different sources. LST data retrieved from the Geostationary Operational Environmental Satellites are assimilated into these two VDA schemes. Sensible and latent heat flux estimates from the CS and DS models are compared with the corresponding measurements from flux tower stations. The results indicate that the performance of both models at dry, lightly vegetated sites is better than that at wet, densely vegetated sites. Additionally, the DS model outperforms the CS model at all sites, implying that the DS scheme is more reliable and can characterize the underlying physics of the problem better.

Xu, Tongren; Bateni, S. M.; Liang, S.; Entekhabi, D.; Mao, Kebiao

2014-09-01

243

A Model for Calculating Desert Aerosol Turbidity over the Oceans from Geostationary Satellite Data  

Microsoft Academic Search

A technique has been developed to infer the optical thickness of Saharan dust from Synchronous Meteorological Satellite (SMS) brightness measurements at visible wavelengths. The scattering model consists of an air layer, a dust layer and a lower boundary of variable albedo. Single-scatter properties of the dust computed from Mie theory were the basis for calculations by plane-parallel theory of radiative

Carl C. Norton; Frederick R. Mosher; Barry Hinton; David W. Martin; David Santek; William Kuhlow

1980-01-01

244

Time and frequency comparisons in Europe by means of ECS 5 geostationary satellite  

Microsoft Academic Search

A time synchronization experiment between some European laboratories using the passive television method applied to the signals broadcasted by Eutelsat I-F5 telecommunication satellite was completed in 1990. The results obtained in the last period, when also range measurements from a Telespazio ground station were performed, are analyzed to evaluate the accuracy level of the time comparisons corrected for the effect

Franco Cordara; V. Pettiti; A. Cenci; M. Fermi; C. Sciarretta

1990-01-01

245

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

246

Prediction of relativistic electron flux at geostationary orbit following storms: Multiple regression analysis  

NASA Astrophysics Data System (ADS)

solar wind and magnetosphere parameters correlate with relativistic electron flux following storms. These include relativistic electron flux before the storm; seed electron flux; solar wind velocity and number density (and their variation); interplanetary magnetic field Bz, AE and Kp indices; and ultra low frequency (ULF) and very low frequency (VLF) wave power. However, as all these variables are intercorrelated, we use multiple regression analyses to determine which are the most predictive of flux when other variables are controlled. Using 219 storms (1992-2002), we obtained hourly averaged electron fluxes for outer radiation belt relativistic electrons (>1.5 MeV) and seed electrons (100 keV) from Los Alamos National Laboratory spacecraft (geosynchronous orbit). For each storm, we found the log10 maximum relativistic electron flux 48-120 h after the end of the main phase of each storm. Each predictor variable was averaged over the 12 h before the storm, the main phase, and the 48 h following minimum Dst. High levels of flux following storms are best modeled by a set of variables. In decreasing influence, ULF, seed electron flux, Vsw and its variation, and after-storm Bz were the most significant explanatory variables. Kp can be added to the model, but it adds no further explanatory power. Although we included ground-based VLF power from Halley, Antarctica, it shows little predictive ability. We produced predictive models using the coefficients from the regression models and assessed their effectiveness in predicting novel observations. The correlation between observed values and those predicted by these empirical models ranged from 0.645 to 0.795.

Simms, Laura E.; Pilipenko, Viacheslav; Engebretson, Mark J.; Reeves, Geoffrey D.; Smith, A. J.; Clilverd, Mark

2014-09-01

247

History of on-orbit satellite fragmentations  

Microsoft Academic Search

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

David J. Nauer

1992-01-01

248

Orbit acquisition and control strategy for small satellites in inclined eccentric orbits  

NASA Astrophysics Data System (ADS)

A set of missions of small satellites in inclined eccentric orbits is analyzed. Small launchers, which require small satellites, can reduce costs and increase flight opportunities. The launch strategy with selected launchers (Scout, Delta 2, Pegasus), the direct orbit achievement and the dog-leg maneuver use, and the ground-track keeping exclusively based on in-plane maneuvers are described in detail. The analysis shows the in orbit mass and the delta-velocity required to fulfill the mission objectives.

Rondinelli, G.; Graziani, F.

249

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

250

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

251

Kozai's resonance in the orbital motions of CBERS satellites  

NASA Astrophysics Data System (ADS)

The objects orbiting the Earth are classified, basically, in Low Earth Orbit (LEO), Medium Earth Orbit (MEO) and Geosynchronous Orbit (GEO). Most of the objects are found in the LEO region because this region has a big quantity of space debris. Currently, the orbital motions of the cataloged objects can be analyzed using the 2-line element set of the NORAD (North American Defense). In this work, resonant orbital motions of the CBERS (China-Brazil Earth Resource Satellite) satellites are studied using the TLE files of the NORAD. Analyzing the motions of artificial satellites CBERS-1 and CBERS-2, one can observe resonant angles in the neighborhood of the exact 14:1 resonance. The orbital motions of the CBERS satellites can be corrected during your lifetime, because some disturbances, resonance effects or collision risk can affect your mission. These corrections can be seen by the abrupt change in the values of the semi-major axis. In this way, the study of the resonant angles using real data of the artificial satellites is limited to the period without corrections. However, the study involving space debris allows to use a long time and consequently a better analysis about the resonant period in a given region. The results and discussions show the complexity, in the orbital dynamics of these objects, caused by the resonance effects. Figures show the time behavior of the semimajor axis, eccentricity, resonant periods and resonant angles. Energy's curves are observed in the (omega, e) plane of the orbital motions of CBERS satellites indicating the presence of Kozai's resonance in their orbits. Where omega is the argument of pericentre and e is the eccentricity.

Sampaio, Jarbas; Vilhena de Moraes, Rodolpho; Da Silva Fernandes, Sandro

252

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

253

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

NASA Astrophysics Data System (ADS)

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

Hamada, Atsushi; Nishi, Noriyuki; Inoue, Toshiro

2010-05-01

254

Application of the GPS system for preliminary satellite orbit determination  

Microsoft Academic Search

In this paper, we discuss a method of preliminary orbit determination for an artificial satellite based on the navigation message of the GPS constellation. Orbital elements are considered as state variables and a simple dynamic model, based on the classic two-body problem, is used. The observations are formed by range and range and range-rate with respect to four visible GPS.

A. P. M Chiaradia; S da Silva Fernandes; R. Vilhena de Moraes

1997-01-01

255

Long range orbital error estimation for applications satellites  

NASA Technical Reports Server (NTRS)

A method of optimum orbital averaging was employed to study the long range accuracy potential of polar orbiting applications satellites. This approach involved the determination of the boundary conditions of one set of differential equations of motion by adjusting the initial conditions in a least square sense with the use of data generated by another set of differential equations of motion.

Bonavito, N. L.; Foreman, J. C.

1978-01-01

256

Huge "Structure" of Satellites Found Orbiting Milky Way  

E-print Network

the Milky Way, the Bonn team proposes that our home galaxy collided with a galactic neighbor about 11Huge "Structure" of Satellites Found Orbiting Milky Way Grouping of galaxies puts cosmology A huge "structure" of satellite galaxies and star clusters has been found wheeling around the Milky Way

Belogay, Eugene A.

257

Improved satellite repeater amplitude-frequency measurement  

Microsoft Academic Search

After the launch of a communications satellite into geostationary orbit, satellite performance is checked by means of a series of in-orbit tests. One of the most important of these tests is the measurement of the amplitude-frequency response (in-band and out-of-band) of each satellite transponder. The present investigation is concerned with a novel satellite in-orbit amplitude-frequency measurement scheme, and the presentation

P. Daly

1983-01-01

258

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

259

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

260

Application of the GPS system for preliminary satellite orbit determination  

NASA Astrophysics Data System (ADS)

In this paper, we discuss a method of preliminary orbit determination for an artificial satellite based on the navigation message of the GPS constellation. Orbital elements are considered as state variables and a simple dynamic model, based on the classic two-body problem, is used. The observations are formed by range and range and range-rate with respect to four visible GPS. A discrete Kalman filter with simulated data is used as filtering technique. The data are obtained through numerical propagation (Cowell's method), which considers special perturbations for the GPS satellite constellation and a user satellite.

Chiaradia, A. P. M.; da Silva Fernandes, S.; de Moraes, R. Vilhena

261

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

262

Sirius XM Satellite Radio system overview and services  

Microsoft Academic Search

Sirius XM Radio, through its Sirius and XM Satellite Radio systems, broadcasts continuous high quality audio, video and data content to over nineteen million subscribers throughout the Continental United States (CONUS) and Canada. The original Sirius system utilizes three satellites in highly inclined orbits. The original XM system utilizes two satellites in geostationary orbits. Both systems achieve a coverage pattern

Stefano DiPierro; Riza Akturan; Richard Michalski

2010-01-01

263

Geostationary multipurpose platforms  

NASA Technical Reports Server (NTRS)

In addition to the advantages generally associated with orbital platforms, such as improved reliability, economies of scale, simple connectivity of elements, reduced tracking demands and the restraint of orbital object population growth, geostationary platforms yield: (1) continuous access by fixed ground antennas for communications services; (2) continuous monitoring of phenomena over chosen regions of the earth's surface; (3) a preferred location for many solar-terrestrial physics experiments. The geostationary platform also offers a low-risk and economical solution to the impending saturation of the orbital arc/frequency spectrum, maximizing the capacity of individual slots and increasing the utility of the entire arc. It also allows the use of many small, simple and inexpensive earth stations through complexity inversion and high power per beam. Block diagram and operational flowcharts are provided.

Bekey, I.; Bowman, R. M.

1981-01-01

264

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

NASA Astrophysics Data System (ADS)

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

Cammalleri, C.; Ciraolo, G.

2013-04-01

265

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

266

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

267

Operational retrieval of Asian sand and dust storm from FY-2C geostationary meteorological satellite and its application to real time forecast in Asia  

NASA Astrophysics Data System (ADS)

This paper describes an operational retrieval algorithm for the sand/dust storm (SDS) from FY-2C/S-VISSR (Stretched-Visible and Infrared Spin-Scan Radiometer) developed at the National Satellite Meteorological Center (NSMC) of China. This algorithm, called Dust Retrieval Algorithm based on Geostationary Imager (DRAGI), is based on the optical and radiative physical properties of SDS in mid-infrared and thermal infrared spectral regions as well as the observation of all bands in the geostationary imager, which include the Brightness Temperature Difference (BTD) in split window channels, Infrared Difference Dust Index (IDDI) and the ratio of middle infrared reflectance to visible reflectance. It also combines the visible and water vapor bands observation of the geostationary imager to identify the dust clouds from the surface targets and meteorological clouds. The output product is validated by and related to other dust aerosol observations such as the synoptic weather reports, surface visibility, aerosol optical depth (AOD) and ground-based PM10 observations. Using the SDS-IDD product and a data assimilation scheme, the dust forecast model CUACE/Dust achieved a substantial improvement to the SDS predictions in spring 2006.

Hu, X. Q.; Lu, N. M.; Niu, T.; Zhang, P.

2008-03-01

268

Elisabeth FRAGNER: Prediction of satellite orbits with SLR (completed in May 1998)  

E-print Network

Satellite and Lunar Laser Ranging Subcommission (Commission on International Coordination of SpaceElisabeth FRAGNER: Prediction of satellite orbits with SLR (completed in May 1998) The modelling of artificial satellite orbits is nowadays often precondition for subsequent geodynamic

Schuh, Harald

269

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

270

CASTOR: Cathode/Anode Satellite Thruster for Orbital Repositioning  

NASA Technical Reports Server (NTRS)

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

Mruphy, Gloria A.

2010-01-01

271

A numerical testbed for remote sensing of aerosols, and its demonstration for evaluating retrieval synergy from a geostationary satellite constellation of GEO-CAPE and GOES-R  

NASA Astrophysics Data System (ADS)

We present a numerical testbed for remote sensing of aerosols, together with a demonstration for evaluating retrieval synergy from a geostationary satellite constellation. The testbed combines inverse (optimal-estimation) software with a forward model containing linearized code for computing particle scattering (for both spherical and non-spherical particles), a kernel-based (land and ocean) surface bi-directional reflectance facility, and a linearized radiative transfer model for polarized radiance. Calculation of gas absorption spectra uses the HITRAN (HIgh-resolution TRANsmission molecular absorption) database of spectroscopic line parameters and other trace species cross-sections. The outputs of the testbed include not only the Stokes 4-vector elements and their sensitivities (Jacobians) with respect to the aerosol single scattering and physical parameters (such as size and shape parameters, refractive index, and plume height), but also DFS (Degree of Freedom for Signal) values for retrieval of these parameters. This testbed can be used as a tool to provide an objective assessment of aerosol information content that can be retrieved for any constellation of (planned or real) satellite sensors and for any combination of algorithm design factors (in terms of wavelengths, viewing angles, radiance and/or polarization to be measured or used). We summarize the components of the testbed, including the derivation and validation of analytical formulae for Jacobian calculations. Benchmark calculations from the forward model are documented. In the context of NASAs Decadal Survey Mission GEO-CAPE (GEOstationary Coastal and Air Pollution Events), we demonstrate the use of the testbed to conduct a feasibility study of using polarization measurements in and around the O2A band for the retrieval of aerosol height information from space, as well as an to assess potential improvement in the retrieval of aerosol fine and coarse mode aerosol optical depth (AOD) through the synergic use of two future geostationary satellites, GOES-R (Geostationary Operational Environmental Satellite R-series) and TEMPO (Tropospheric Emissions: Monitoring of Pollution). Strong synergy between GEOS-R and TEMPO are found especially in their characterization of surface bi-directional reflectance, and thereby, can potentially improve the AOD retrieval to the accuracy required by GEO-CAPE.

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

2014-10-01

272

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

273

Numerical orbit generators of artificial earth satellites  

Microsoft Academic Search

A numerical orbit integrator containing updatings and improvements relative to the previous ones that are being utilized by the Departmento de Mecanica Espacial e Controle (DMC), of INPE, besides incorporating newer modellings resulting from the skill acquired along the time is presented. Flexibility and modularity were taken into account in order to allow future extensions and modifications. Characteristics of numerical

H. K. Kugar; W. C. C. Dasilva

1984-01-01

274

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

NASA Astrophysics Data System (ADS)

The PCW (Polar Communications and Weather) mission is a dual satellite mission with each satellite in a highly eccentric orbit with apogee ~42,000 km and a period (to be decided) in the 12-24 hour range to deliver continuous communications and meteorological data over the Arctic and environs. Such as satellite duo can give 24×7 coverage over the Arctic. The operational meteorological instrument is a 21-channel spectral imager similar to the Advanced Baseline Imager (ABI). The PHEOS-WCA (weather, climate and air quality) mission is intended as an atmospheric science complement to the operational PCW mission. The target PHEOS-WCA instrument package considered optimal to meet the full suite of science team objectives consists of FTS and UVS imaging sounders with viewing range of ~4.5° or a Field of Regard (FoR) ~ 3400×3400 km2 from near apogee. The goal for the spatial resolution at apogee of each imaging sounder is 10×10 km2 or better and the goal for the image repeat time is targeted at ~2 hours or better. The FTS has 4 bands that span the MIR and NIR with a spectral resolution of 0.25 cm-1. They should provide vertical tropospheric profiles of temperature and water vapour in addition to partial columns of many other gases of interest for air quality. The two NIR bands target columns of CO2, CH4 and aerosol optical depth (OD). The UVS is an imaging spectrometer that covers the spectral range of 280-650 nm with 0.9 nm resolution and targets the tropospheric column densities of O3 and NO2 and several other Air Quality (AQ) gases as well the Aerosol Index (AI).

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

2012-09-01

275

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

276

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

277

Effect of resonance-oblateness coupling on a satellite orbit  

NASA Technical Reports Server (NTRS)

Second order effects of the coupling between geopotential resonance and oblateness on a satellite orbit are calculated. Results show that: (1) these effects arise from the interaction of resonance with the secular changes of the orbit's node, perigee, and mean anomaly; (2) they have the same period and phase as first order resonance perturbations; and (3) their amplitudes are proportional to the square of the period and dominate the first order effects as the orbit becomes commensurate. A striking example of this coupling is seen in the 18 day resonance variation of the node of the orbit of the first earth resources technology satellite. Analysis of this one arc second (31m) variation yielded a strong 14th order constraint to the geopotential for odd degree terms. This constraint is poorly predicted by current models.

Wagner, C. A.

1974-01-01

278

Atmospheric aerosol loading polarimetry: full-orbit satellite data simulation  

NASA Astrophysics Data System (ADS)

SPoRTMap is a system simulation tool for satellite-based polarimetric aerosol measurements. It integrates a large number of the tasks needed to simulate polarimetric Earth observations from satellite sensors: phenomenology model setup and run, sensor geometry setup, integration of sensor radiometric models, interpolation from model grid to sensor field of view, Stokes parameter SNR computations, etc. The architecture of the simulation system is modular to enable replacement of radiative transfer and sensor noise models. Operation of SPoRTMap is illustrated through creation of an orbital simulation using a specific aerosol model. Integration of diverse aerosol models into orbital mosaics is shown.

Illing, Rainer M. E.; Petroy, Shelley B.

2004-10-01

279

Orbits design for LEO space based solar power satellite system  

NASA Astrophysics Data System (ADS)

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

Addanki, Neelima Krishna Murthy

280

On-Orbit Calibration of Satellite Gyroscopes  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

281

Ozone air quality measurement requirements for a geostationary satellite mission Peter Zoogman a,*, Daniel J. Jacob a,b  

E-print Network

through data assimilation. Our purpose is to define instrument requirements for the NASA GEO for Astrophysics, Cambridge, MA, United States d Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ, United t We conduct an Observing System Simulation Experiment (OSSE) to test the ability of geostationary

Chance, Kelly

282

High-resolution satellite imagery for mesoscale meteorological studies  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

283

A mathematical simulation of earth satellite explosion debris orbital elements  

E-print Network

A MATHEMATICAL SIKJLATION OF EARTH SATELLITE EXPLOSION DEBRIS ORBITAI ELEMENTS A Thesis WAYNE EDWARD NABREY Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of NASTER OF SCIENCE... Nay 1970 Major Subject Nathematics A MATHEMATICAL SlmZATION OZ EARTH SATELLITE EXPLOSION DEBRIS ORBITAL ELEMENTS A Thesis WAI? EDWARD MABREY Approved as to style and content by: haxrman o ommi tee Head o epartment mber Member May 1...

Mabrey, Wayne Edward

2012-06-07

284

Two Atmospheric Effects in the Orbital Acceleration of Artificial Satellites  

Microsoft Academic Search

As I first pointed out1, the orbital acceleration of artificial Earth satellites shows fluctuations which cannot be explained on gravitational grounds. In satellite 1957 beta 1, these oscillations were rather irregular, although cycles of 19 and 37 days could be discerned2,3. According to E. C. Cornford4, a periodicity of about 25 days was indicated, and this gave rise to speculations

Luigi G. Jacchia

1959-01-01

285

EUROPE'S GEOSTATIONARY METEOROLOGICAL SATELLITES  

E-print Network

MISSIONS MFG MISSION MSG MISSION MTG IMAGING MISSION MTG I MTG SOUNDING MISSION MTG S * MSG 4/METEOSAT 11 MTG S 1 MTG S 2 METEOSAT 9 MSG 3/METEOSAT 10 MSG 4/METEOSAT 11* METEOSAT FIRST GENERATION METEOSAT services over Europe and Africa, are now exclusively provided by Meteosat Second Generation (MSG

Stoffelen, Ad

286

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

287

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

288

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

289

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

290

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

291

Introduction to satellite constellations orbital types, uses and related facts  

E-print Network

military; then Russian satellite television in 1960s. 63.4º inclination. #12;Molnya · Molnya (0.5sd ~12hr) and Tundra (~24hr 1sd orbits) ­ cover high latitudes at apogee. · Invented by Soviet military; then Russian shown for scale · Sirius Radio adopts this model over the continental US. (XM Radio has two GEO

Wood, Lloyd

292

Solid Earth and ocean tides estimated from satellite orbit analyses  

Microsoft Academic Search

The earth's tidal deformations cause perturbations in the motions of close earth satellites, observations of which give estimates of the Love number k2 and phase lag ?. The contribution of the ocean tides has generally been considered unimportant, but this is not so. These ocean tides cause the same spectrum of orbital perturbations as the solid tide, and a complete

Kurt Lambeck; Anny Cazenave; Georges Balmino

1974-01-01

293

Application and analysis of satellite orbit prediction techniques  

NASA Technical Reports Server (NTRS)

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

1977-01-01

294

Atmospheric Density Reconstruction Using Satellite Orbit Tomography1  

E-print Network

neutral density models are required for the reduction of orbit prediction errors for satellites-based approach, inspired by X-ray computed tomography from the medical imaging field. The change in specific over 324 grid elements spanning 300 to 500 km altitude. This ill-posed problem is solved us- ing

Wohlberg, Brendt

295

Analytical solution of a satellite orbit disturbed by atmospheric drag  

NASA Astrophysics Data System (ADS)

In this paper, we derive the analytical solution of a satellite orbit disturbed by atmospheric drag. The disturbance force vector is first transformed and rotated to the orbital frame so that it can be used in the simplified Gaussian equations of satellite motion. Then, the force vector is expanded to triangular functions of the Keplerian angular elements and the disturbances are separated into three parts: short-periodic terms with triangular functions of M, long-periodic terms with triangular functions of (?, i) and secular terms [non-periodic functions of (a, e)] with a program using mathematical symbolic operation software. The integrations are then carried out with respect to M, (?, i) and t, respectively, to obtain the analytical solutions of satellite orbits disturbed by atmospheric drag. Some interesting conclusions are obtained theoretically. The atmospheric disturbance force is not a function of ?. The semimajor axis a of the orbital ellipse is reduced in a constant and strong manner by the air disturbance; the shape of the ellipse (eccentricity e) changes towards a more circular orbit in a linear and weak manner. The right ascension of the ascending node ? and the mean anomaly M are influenced by the disturbance only short periodically.

Xu, Guochang; Tianhe, Xu; Chen, Wu; Yeh, Ta-Kang

2011-01-01

296

Geostationary atmospheric infrared sounder: trace gases sensitivity  

NASA Astrophysics Data System (ADS)

The NASA sponsored Advanced Geosynchronous Studies (AGS) program is to conduct intensive studies to demonstrate the use of advanced new technologies and instruments on geosynchronous satellites to improve our current capabilities of monitoring the global weather, climate, and chemistry. The Geostationary Atmospheric Sounder (GAS), to be developed under AGS, is intended to demonstrate a new space-based infrared imaging interferometer that is well suited for achieving the high temporal and spatial global coverage of cloud motion, water vapor transport, thermal and moisture vertical profiles, land and ocean surface temperature, and trace gas concentrations. The AGS technology demonstrations will show the capabilities of passive infrared observations from future NOAA geostationary operational sounders. The focus of this presentation is to provide quantitative assessments of a few design configurations for the trace gases sounding feasibility from geostationary orbit. Trade-off studies of spectral, temporal, and spatial resolution are to be emphasized. Preliminary conclusions for the design of an operational geo sounder for chemistry applications will be made.

Huang, Allen H.; Li, Jun; Thom, Jonathan; Huang, Bormin; Smith, William L.; Woods-Vedeler, Jessica; Parsons, Vicki S.

1999-10-01

297

Orbital Perturbations of the Galilean Satellites During Planetary Encounters  

E-print Network

The Nice model of the dynamical instability and migration of the giant planets can explain many properties of the present Solar System, and can be used to constrain its early architecture. In the jumping-Jupiter version of the Nice model, required from the terrestrial planet constraint and dynamical structure of the asteroid belt, Jupiter has encounters with an ice giant. Here we study the survival of the Galilean satellites in the jumping-Jupiter model. This is an important concern because the ice-giant encounters, if deep enough, could dynamically perturb the orbits of the Galilean satellites, and lead to implausible results. We performed numerical integrations where we tracked the effect of planetary encounters on the Galilean moons. We considered three instability cases from Nesvorny & Morbidelli (2012) that differed in the number and distribution of encounters. We found that in one case, where the number of close encounters was relatively small, the Galilean satellite orbits were not significantly af...

Deienno, R; Vokrouhlicky, D; Yokoyama, T

2014-01-01

298

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

NASA Technical Reports Server (NTRS)

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

Welch, Bryan W.

2007-01-01

299

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

300

The Use of Resonant Orbits in Satellite Geodesy: A Review  

NASA Astrophysics Data System (ADS)

Dynamic resonance, arising from commensurate (orbital or rotational) periods of satellites or planets with each other, has been a strong force in the development of the solar system. The repetition of conditions over the commensurate periods can result in amplified long-term changes in the positions of the bodies involved. Such resonant phenomena driven by the commensurability between the mean motion of certain artificial Earth satellites and the Earth's rotation originally contributed to the evaluation and assessment of the Stokes parameters (harmonic geopotential coefficients) that specify the Earth's gravitational field. The technique constrains linear combinations of the harmonic coefficients that are of relevant resonant order (lumped coefficients). The attraction of the method eventually dwindled, but the very accurate orbits of CHAMP and GRACE have recently led to more general insights for commensurate orbits applied to satellite geodesy involving the best resolution for all coefficients, not just resonant ones. From the GRACE mission, we learnt how to explain and predict temporary decreases in the resolution and accuracy of derived geopotential parameters, due to passages through low-order commensurabilities, which lead to low-density ground-track patterns. For GOCE we suggest how to change a repeat orbit height slightly, to achieve the best feasible recovery of the field parameters derived from on-board gradiometric measurements by direct inversion from the measurements to the harmonic geopotential coefficients, not by the way of lumped coefficients. For orbiters of Mars, we have suggestions which orbits should be avoided. The slow rotation of Venus results in dense ground-tracks and excellent gravitational recovery for almost all orbiters.

Kloko?ník, J.; Gooding, R. H.; Wagner, C. A.; Kostelecký, J.; Bezd?k, A.

2013-01-01

301

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

302

Unique operations for a highly inclined, elliptical, geosynchronous satellite  

NASA Astrophysics Data System (ADS)

The first space segment devoted to a Digital Audio Radio Service (DARS) for the Continental United States (CONUS) was established when the last satellite of a three satellite constellation (Flight Models FM-1, FM-2 and FM-3) was launched in November 2000. Each satellite is in a highly inclined, elliptical, geosynchronous orbit that is separated by 120° in Right Angle of the Ascending Node (RAAN) from the other two satellites' orbits. This results in an 8 h phasing in ground track between each satellite. These distinct orbits provide superior look angles and signal availability to mobile receivers in the northern third of the United States when compared to geostationary satellites. However, this unique orbital constellation results in some particular performance and operational differences from geostationary orbit satellites. Some of these are: Earth Sensor noise, maneuver implementation and power management. Descriptions and performance improvements of these orbit specific operations are detailed herein.

Anglin, Patrick T.; Briskman, Robert D.

2004-08-01

303

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

304

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

E-print Network

Heat Transfer - 1 A satellite in space orbits the sun. The satellite can be approximated as a flat the temperature of the satellite. (30%) (c) At time t=0, the satellite passes behind Mars such that the sun that the satellite has a uniform temperature at all times while it cools. (45%) Boltzmann's constant, = 5.67 10-8 W

Virginia Tech

305

Hybrid Global Communication Architecture with Balloons and Satellites  

Microsoft Academic Search

Global space communication systems have been developed now for more than three decades, based mainly on geostationary satellites or almost equivalent systems such as the Molnya orbit concepts. The last decade of the twentieth century has seen the emergence of satellite constellations in low or medium Earth orbit, in order to improve accessibility in terms of visibility at higher latitudes

G. Pignolet; A. Celeste; B. Erb

2002-01-01

306

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, Robert A.

1999-01-01

307

Using Crossover Data from Satellite Altimeter for Orbit Determination  

NASA Astrophysics Data System (ADS)

Beginning from the development status of oceanic altimeter satellites, the significance of orbit determination using altimeter data is introduced. Then, the error correcting model of altimeter data and the calculation method of crossover data are analyzed. The error correcting parameters and the adopted models which are concerned in the altimeter data files of JASON-1 are also introduced in detail. Finally, through the calculations of the simulated data and observational data, the orbit determination accuracies which can be reached by using the altimeter data and crossover data are analyzed. This work provides a valuable reference to the practical applications in future.

Zhang, R. Z.; Zhou, F. Q.; Xiong, J.

2010-07-01

308

Shuttle orbiter - IUS/DSP satellite interface contamination study  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

309

GPS single-frequency orbit determination for low Earth orbiting satellites  

NASA Astrophysics Data System (ADS)

The determination of high-precision orbits for Low Earth Orbiting (LEO) satellites (e.g., CHAMP, GRACE, MetOp-A) is based on dual-frequency tracking data from on-board GPS (Global Positioning System) receivers. The two frequencies allow it to eliminate the first order ionosphere effects. Data screening and precise orbit determination (POD) procedures are optimized under the assumption of the availability of two frequencies. If only single-frequency data is available, the algorithms have to be modified to consider the ionospheric effect. We develop and study different approaches for POD with single-frequency data. Reduced-dynamic as well as kinematic POD techniques using pseudorange and carrier phase GPS data are considered. One week of data in the year 2007 is used to assess the potential of single-frequency POD in different environments by comparing the results with dual-frequency POD for LEOs orbiting the Earth in different heights. Data from the two GRACE and the MetOp-A satellites is processed for this purpose. Moreover, the impact of different data sampling rates on single-frequency POD is considered. For this period with low solar activity a 3D orbit accuracy of 1 dm could be reached for one of the GRACE satellites. It could be shown that it is necessary to have a high data sampling of 10 s or more available when the impact of the ionosphere is high due to low altitude of the satellite or high solar activity. Our study helps to define requirements for GNSS (Global Navigation Satellite System) receivers and POD algorithms for future LEO missions for which only moderate orbit accuracy of about one to few decimeter is needed.

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

2009-03-01

310

Requirement Analysis of Orbital Parameters in the Satellite-to-Satellite Tracking Model  

NASA Astrophysics Data System (ADS)

The 21st century is a new epoch that human beings upgrade the cognitive capabilities to the Digital Earth using the SST (Satellite-to-Satellite Tracking) and SGG (Satellite Gravity Gradiometry) techniques. The requirement analysis of orbital parameters in the SST model is carried out for the first time using the combined models of cumulative geoid height errors influenced by the range-rate error of K-band ranging system, orbital error of GPS receiver and nonconservative force error of accelerometer from GRACE satellites based on the semi-analytical method in this study. The simulated results are as follows: (1) The matched relationship of accuracy indexes from key payloads including K-band ranging system, GPS receiver and accelerometer is obtained using the semi-analytical method; (2) The GRACE global gravitational field is estimated based on different average orbital altitudes (500 km, 450 km, 400 km, 350 km, 300 km, 250 km and 200 km) and average intersatellite ranges (110 km, 220 km and 330 km). The optimal design of average orbital altitude 400 km and intersatellite range 220 km is suggested in the future first gravity satellite in China. The reasons why the preferable orbital altitude and intersatellite range are selected are analyzed and demonstrated in detail. This work not only can provide theoretical foundation and calculational guarantee for the optimal selection of orbital parameters and efficient and rapid estimation on the accuracy of global gravitational field in the future satellite gravity measurement in China, but also has some guiding significance to the development direction of future international GRACE Follow-On Earth's gravity measurement mission and GRAIL lunar gravity exploration program.

Zheng, W.; Hsu, H. T.; Zhong, M.; Yun, M. J.; Zhou, X. H.; Peng, B. B.

2010-01-01

311

GOCE satellite orbit in the aspect of selected gravitational perturbations  

Microsoft Academic Search

In this work, the GOCE satellite orbit is described in the aspect of perturbations in the Keplerian osculating elements. The\\u000a perturbations come from the Earth and ocean tides, the gravitation of the Moon, the gravitation of the Sun, the gravitation\\u000a of planets and Pluto, and the relativity effects. These perturbations are computed for the 30-day interval with a sampling\\u000a of

Andrzej Bobojc; Andrzej Drozyner

2011-01-01

312

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

313

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

NASA Technical Reports Server (NTRS)

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

Paul, M. P.

1982-01-01

314

Revisiting elliptical satellite orbits to enhance the O3b constellation  

E-print Network

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

Wood, Lloyd

315

Evaluation of IGS Orbits with Satellite Laser Ranging  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

316

The Sudden Discontinuity in the Orbital Period of Sputnik 4 Satellite  

Microsoft Academic Search

THE orbit of the fourth Russian Earth satellite soon after its late launching on May 14, 1960, was similar to the orbits of the previous Sputniks, as may be seen from the orbital elements shown in Table 1. A Tass News Agency report of May 17 indicated that there were two objects close together in orbit-the composite satellite itself, consisting

B. R. May; D. E. Smith

1960-01-01

317

Application of extended Lagrange series to the precise determination of Global Positioning Satellite orbits  

Microsoft Academic Search

A new semi-analytical method is presented for solving the calculation of the perturbed orbits of Global Positioning System (GPS) satellites. Preliminary notions concerning coordinates, Keplerian orbits, and the perturbed orbit are established. The basic principles of the analytical and numerical method are introduced along with the models of the principal perturbations affecting the GPS satellites. Different methods of orbit calculation

Caroline Huot

1993-01-01

318

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

NASA Astrophysics Data System (ADS)

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

Tang, J. S.

2011-03-01

319

Geostationary Environment Monitoring Spectrometer (GEMS)  

NASA Astrophysics Data System (ADS)

GEMS(Geostationary Environment Monitoring Spectrometer) is a scanning UV-visible spectrometer to be onboard the GeoKOMPSAT-2B in geostationary orbit in 2018. The main objective of the mission is to measure concentration of ozone and aerosol with their precursors including NO2, SO2 and HCHO in high temporal and spatial resolution. Recently, GEMS passed the governmental mid-term technical review, thus is in main phase of the mission. System design review(SDR) of GEMS was completed successfully and preliminary design review(PDR) is planned in March, 2014. Spectral coverage of GEMS is 300 to 500 nm with resolution of 0.6 nm and 3 samples/band. The mission covers most of the interesting region in Asia, with occasional coverage out to Pacific for clear sector method. Algorithms are under the development. Error analysis was carried out using the optimal estimation method with TOMS climatology, GEOS-Chem and VLIDORT. For the analysis, randomly generated conditions were extracted for different time of day in 12 months with actual viewing geometry from a GEO satellite at 128.2 oE. Through the spatial and spectral coadding and flexible E-W scan to increase the SNR, the performance of GEMS is predicted to satisfy the science requirements in most of the cases. Measurements of SO2 in winter season is very challenging but can be resolved if 4 pixels are coadded and the E-W scan is reduced half to increase SNR. GEMS is a part of GEO air quality(AQ) constellation with the Sentinel-4 of ESA and the TEMPO of NASA. Harmonized efforts for the GEO AQ Constellation are underway in terms of common basic requirements, standards, data product quality and cross participation of meetings under the framework of CEOS ACC.

Kim, Jhoon

320

GOCE satellite orbit in the aspect of selected gravitational perturbations  

NASA Astrophysics Data System (ADS)

In this work, the GOCE satellite orbit is described in the aspect of perturbations in the Keplerian osculating elements. The perturbations come from the Earth and ocean tides, the gravitation of the Moon, the gravitation of the Sun, the gravitation of planets and Pluto, and the relativity effects. These perturbations are computed for the 30-day interval with a sampling of 2 min. To obtain the simulated orbit, the Cowell numerical integration method of 8th order is used. The first part of the work contains the root mean square (RMS) values of aforementioned perturbations due to the specified forces. The perturbations were compared taking into account their RMS characteristics. Perturbations in elements of the GOCE osculating orbit are also presented on the plots for successive epochs of the 30-day interval. Changes of the obtained perturbations were described and their characteristic periodic components were distinguished.

Boboj?, Andrzej; Dro?yner, Andrzej

2011-04-01

321

The enigma of the Uranian satellites' orbital eccentricities  

NASA Technical Reports Server (NTRS)

The eccentricity decay times for the Uranian satellites are calculated using recent observations (Brown et al., 1982) of the diameters and orbital elements of the satellites and assuming reasonable dissipation functions and rigidities for icy satellites. For the outer two satellites, Titania and Oberon, the decay times are found to be very long, whereas the inner three satellites, Miranda, Ariel, and Umbriel, have decay times on the order of 10 to the 7th to 10 to the 8th years and have a near-commensurability in their mean motions that cannot force their eccentricities. There are several possible solutions for the lack of resonant forcing: (1) the reported eccentricities are incorrect, and are very nearly zero, (2) the reported mean motions are incorrect, and an exact commensurability exists, (3) the physical properties assumed for the satellites are grossly in error, and (4) the system is evolving rapidly, perhaps from a previous state of higher eccentricity. A new lower bound of about 17,000 on the dissipation function of Uranus is calculated from the mass of Ariel and its proximity to Uranus.

Squyres, S. W.; Reynolds, R. T.; Lissauer, J. J.

1985-01-01

322

GPS based onboard and onground orbit operations for small satellites  

NASA Astrophysics Data System (ADS)

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 exclusive source of orbital information simplifies the operations concept and reduces mission costs through the extensive use of existing low-cost mission support software. Due to small computer resource requirements of 8-10kByte, the SGP4 model may also be applied for onboard orbit computations making use of e.g. a 80186 processor, thus ensuring full compatibility of ground-based and onboard operations. The proposed approach is particularly suited in combination with a space-borne GPS receiver, were the C/A-code navigation solutions are treated as measurements that are adjusted in a least-squares sense using the SGP4 model. As consequence, inherent drawbacks of the pure navigation solutions such as data gaps and scatter as well as limited velocity accuracy are avoided, while the operational navigation activities are kept at a minimum. The feasibility of the concept is illustrated based on real GPS navigation data from the TOPEX/Poseidon and the MIR space station with an inherent data quality of 50-100 m. It is shown that 3 hours of data within a 4 day period are sufficient to keep the position error within 4 km, that is considered sufficient for most applications.

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

1996-11-01

323

Atmospheric density estimation using satellite precision orbit ephemerides  

NASA Astrophysics Data System (ADS)

The current atmospheric density models are not capable enough to accurately model the atmospheric density, which varies continuously in the upper atmosphere mainly due to the changes in solar and geomagnetic activity. Inaccurate atmospheric modeling results in erroneous density values that are not accurate enough to calculate the drag estimates acting on a satellite, thus leading to errors in the prediction of satellite orbits. This research utilized precision orbit ephemerides (POE) data from satellites in an orbit determination process to make corrections to existing atmospheric models, thus resulting in improved density estimates. The work done in this research made corrections to the Jacchia family atmospheric models and Mass Spectrometer Incoherent Scatter (MSIS) family atmospheric models using POE data from the Ice, Cloud and Land Elevation Satellite (ICESat) and the Terra Synthetic Aperture Radar-X Band (TerraSAR-X) satellite. The POE data obtained from these satellites was used in an orbit determination scheme which performs a sequential filter/smoother process to the measurements and generates corrections to the atmospheric models to estimate density. This research considered several days from the year 2001 to 2008 encompassing all levels of solar and geomagnetic activity. Density and ballistic coefficient half-lives with values of 1.8, 18, and 180 minutes were used in this research to observe the effect of these half-life combinations on density estimates. This research also examined the consistency of densities derived from the accelerometers of the Challenging Mini Satellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites by Eric Sutton, from the University of Colorado. The accelerometer densities derived by Sutton were compared with those derived by Sean Bruinsma from CNES, Department of Terrestrial and Planetary Geodesy, France. The Sutton densities proved to be nearly identical to the Bruinsma densities for all the cases considered in this research, thus suggesting that Sutton densities can be used as a substitute for Bruinsma densities in validating the POE density estimates for future work. Density estimates were found using the ICESat and TerraSAR-X POE data by generating corrections to the CIRA-72 and NRLMSISE-00 atmospheric density models. The ICESat and TerraSAR-X POE density estimates obtained were examined and studied by comparing them with the density estimates obtained using CHAMP and GRACE POE data. The trends in how POE density estimates varied for all four satellites were found to be the same or similar. The comparisons were made for different baseline atmospheric density models, different density and ballistic coefficient correlated half-lives, and for varying levels of solar and geomagnetic activity. The comparisons in this research help in understanding the variation of density estimates for various satellites with different altitudes and orbits.

Arudra, Anoop Kumar

324

Geostationary Earth Radiation Budget (GERB) data  

NASA Astrophysics Data System (ADS)

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

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

325

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

Code of Federal Regulations, 2013 CFR

...power flux-density, in the space-to-Earth direction, (EPFD down ) limits ...flux-density (PFD) masks, on the surface of the Earth, for each space station in the NGSO...power flux-density, in the space-to-Earth direction, (additional operational...

2013-10-01

326

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

Code of Federal Regulations, 2011 CFR

... false Time sharing between NOAA meteorological satellite systems and non-voice...25.259 Time sharing between NOAA meteorological satellite systems and non-voice...for obtaining the necessary ephemeris data. This information shall be...

2011-10-01

327

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

Code of Federal Regulations, 2012 CFR

... false Time sharing between NOAA meteorological satellite systems and non-voice...25.259 Time sharing between NOAA meteorological satellite systems and non-voice...for obtaining the necessary ephemeris data. This information shall be...

2012-10-01

328

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

Code of Federal Regulations, 2013 CFR

... false Time sharing between NOAA meteorological satellite systems and non-voice...25.259 Time sharing between NOAA meteorological satellite systems and non-voice...responsible for obtaining the ephemeris data necessary for compliance with...

2013-10-01

329

Analysis of Multi-Satellite Tracking Data of the Kaguya Satellites for Orbit and Gravity Field Determination  

Microsoft Academic Search

The Kaguya spacecraft were launched from Tanegashima Space Center on September 14, 2007. Kaguya consists of three orbiters: a main orbiter in a low-altitude (100 km) circular polar orbit, and two sub-satellites (Rstar and Vstar) in elliptical orbits. The satellites were tracked by a variety of terrestrial based tracking systems: in addition to standard two-way Doppler and range tracking, there

S. J. Goossens; K. Matsumoto; F. Kikuchi; Q. Liu; H. Hanada; F. G. Lemoine; D. D. Rowlands; Y. Ishihara; Y. Jianguo; H. Araki; H. Noda; N. Namiki; T. Iwata

2010-01-01

330

Mt. St. Helens eruption as observed by satellite and estimates of its impact on the planetary radiation budget  

Microsoft Academic Search

A study was conducted of the eruption of Mt. St. Helens' on May 18, 1980, taking into account both geostationary and polar orbiting satellite data. The geostationary data made it possible to determine the expansion rates and the growth of the plume from shortly after the explosion to several days afterwards. An investigation of the equivalent blackbody temperature provided an

A. Gruber; A. Krueger; W. Shen; M. Matson

1981-01-01

331

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

E-print Network

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

Heiz, Ulrich

332

Mapping total suspended matter from geostationary satellites: a feasibility study with SEVIRI in the Southern North Sea.  

PubMed

Geostationary ocean colour sensors have not yet been launched into space, but are under consideration by a number of space agencies. This study provides a proof of concept for mapping of Total Suspended Matter (TSM) in turbid coastal waters from geostationary platforms with the existing SEVIRI (Spinning Enhanced Visible and InfraRed Imager) meteorological sensor on the METEOSAT Second Generation platform. Data are available in near real time every 15 minutes. SEVIRI lacks sufficient bands for chlorophyll remote sensing but its spectral resolution is sufficient for quantification of Total Suspended Matter (TSM) in turbid waters, using a single broad red band, combined with a suitable near infrared band. A test data set for mapping of TSM in the Southern North Sea was obtained covering 35 consecutive days from June 28 until July 31 2006. Atmospheric correction of SEVIRI images includes corrections for Rayleigh and aerosol scattering, absorption by atmospheric gases and atmospheric transmittances. The aerosol correction uses assumptions on the ratio of marine reflectances and aerosol reflectances in the red and near-infrared bands. A single band TSM retrieval algorithm, calibrated by non-linear regression of seaborne measurements of TSM and marine reflectance was applied. The effect of the above assumptions on the uncertainty of the marine reflectance and TSM products was analysed. Results show that (1) mapping of TSM in the Southern North Sea is feasible with SEVIRI for turbid waters, though with considerable uncertainties in clearer waters, (2) TSM maps are well correlated with TSM maps obtained from MODIS AQUA and (3) during cloud-free days, high frequency dynamics of TSM are detected. PMID:19654812

Neukermans, Griet; Ruddick, Kevin; Bernard, Emilien; Ramon, Didier; Nechad, Bouchra; Deschamps, Pierre-Yves

2009-08-01

333

Real - Time Orbit Determination of Low Earth Orbit Satellites Using Radar System and SGP4 Model  

NASA Astrophysics Data System (ADS)

In case that we independently obtain orbital informations about the low earth satellites of foreign countries using radar systems, we develop the orbit determination algorithm for this purpose using a SGP4 model with an analytical orbit model and the extended Kalman filter with a real-time processing method. When the state vector is Keplerian orbital elements, singularity problems happen to compute partial derivative with respect to inclination and eccentricity orbit elements. To cope with this problem, we set state vector osculating to mean equinox and true equator cartesian elements with coordinate transformation. The state transition matrix and the covariance matrix are numerically computed using a SGP4 model. Observational measurements are the type of azimuth, elevation and range, filter process to each measurement in a lump. After analyzing performance of the developed orbit determination algorithm using TOPEX/POSEIDON POE(Precision Orbit Ephemeris), its position error has about 1 km. To be similar to performance of NORAD system that has up to 3km position accuracy during 7 days need to radar system performance that have accuracy within 0.1 degree for azimuth and elevation and 50m for range.

Lee, Jae-Kwang; Lee, Sung-Seub; Yoon, Jae-Cheol; Choi, Kyu-Hong

2003-03-01

334

A Low Earth Orbit satellite marine communication system demonstration  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

335

On possibility of minor body's capture to a satellite orbit before collision with Earth  

Microsoft Academic Search

In the context of the asteroid's danger problem, the determination of potentially the most dangerous orbits - the orbits of collision with the Earth - has a significant interest. One kind of orbit of collision is related with Lagrangian libration solution for the three body problem. It is known, that possible (temporary) capture to a satellite orbit from orbit near

A. E. Rosaev

2002-01-01

336

Artificial Crater Formation on Satellite Surfaces Using an Orbiting Railgun  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

337

Laser beaming demonstrations to high-orbit satellites  

SciTech Connect

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

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

1994-12-31

338

Laser beaming demonstrations to high-orbit satellites  

SciTech Connect

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

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

1993-12-31

339

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

340

A fast switching antenna diversity system for improved mobile reception of digital radio signals of a geostationary satellite  

Microsoft Academic Search

In severe multipath propagation scenarios - as for example underneath dense foliage or between buildings - the mobile reception of satellite digital audio radio services (SDARS) can be severely impaired. Antenna diversity is able to increase reception in such scenarios and to increase the link margin of satellite signal transmission. In this contribution a scan-phase antenna diversity system is shown

Simon Senega; Stefan M. Lindenmeier

2011-01-01

341

Orbits and Masses of the Satellites of the Dwarf Planet Haumea (2003 EL61)  

Microsoft Academic Search

Using precise relative astrometry from the Hubble Space Telescope and the W. M. Keck Telescope, we have determined the orbits and masses of the two dynamically interacting satellites of the dwarf planet (136108) Haumea, formerly 2003 EL61. The orbital parameters of Hi'iaka, the outer, brighter satellite, match well the previously derived orbit. On timescales longer than a few weeks, no

Darin Ragozzine; M. E. Brown

2009-01-01

342

Orbit Boosting of an Electrodynamic Tethered Satellite with Input-Shaped Current Arun Banerjee  

E-print Network

of a tethered satellite, the objective being to start and end the orbit transfer with the tether aligned for a time to generate the force-time impulse needed for the orbit transfer. UnfortunatelyOrbit Boosting of an Electrodynamic Tethered Satellite with Input-Shaped Current Arun Banerjee

Singhose, William

343

Mass density of the upper atmosphere derived from Starlette's Precise Orbit Determination with Satellite Laser Ranging  

Microsoft Academic Search

The atmospheric mass density of the upper atmosphere from the spherical Starlette satellite's Precise Orbit Determination is first derived with Satellite Laser Ranging measurements at 815 to 1115 km during strong solar and geomagnetic activities. Starlette's orbit is determined using the improved orbit determination techniques combining optimum parameters with a precise empirical drag application to a gravity field. MSIS-86 and

H. S. Jeon; S. Cho; Y. S. Kwak; J. K. Chung; J. U. Park; D. K. Lee; M. Kuzmicz-Cieslak

2011-01-01

344

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

Microsoft Academic Search

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

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

1998-01-01

345

Interannual variation in biomass burning and fire seasonality derived from geostationary satellite data across the contiguous United States from 1995 to 2011  

NASA Astrophysics Data System (ADS)

exhibit a strong seasonality that is driven by climatic factors and human activities. Although the fire seasonality is commonly determined using burned area and fire frequency, it could also be quantified using biomass consumption estimates that directly represent biomass loss (a combination of the area burned and the fuel loading). Therefore, in this study a data set of long-term biomass consumed was derived from geostationary satellite data to explore the interannual variation in the fire seasonality and the possible impacts of climate change and land management practices across the Contiguous United States (CONUS). Specifically, daily biomass consumed data were derived using the fire radiative power retrieved from Geostationary Operational Environmental Satellites series with a pixel size of 4-10 km from 1995 to 2011. Annual fire seasonality metrics including the fire season duration, the timing of the start, peak, and end of the fire season, and interannual variation and trends were derived from the 17 year biomass consumed record. These metrics were associated with climatic factors to examine drivers and mediators of fire seasonality. The results indicate that biomass consumed significantly increased at a rate of 2.87 Tg/yr; however, the derived fire season duration exhibited a shortening trend in various states over the western CONUS and no significant trend in most other regions. This suggests that the frequency of extreme fire events has increased, which is perhaps associated with an observed increase of extreme weather conditions. Further, both the start and the end of the fire season exhibited an early shift (1.5-5 d/yr) in various eastern states although a late shift occurred in Arizona and Oregon. The interannual variation and trend in the fire seasonality was more strongly related to temperature in the western CONUS and to precipitation in the southeast. The Palmer Drought Severity Index was found to effectively reflect interannual variations in total biomass consumed although it was poorly correlated to the fire seasonality metrics. The results indicate that across the CONUS, the spatial patterns of the start, peak, and end of the fire season shift regularly in various regions in response to latitudinal gradients of temperature variation.

Zhang, Xiaoyang; Kondragunta, Shobha; Roy, David P.

2014-06-01

346

Analysis of tropical cloud systems using a new cloud-top height data by geostationary satellite split-window measurements trained with CloudSat data  

NASA Astrophysics Data System (ADS)

Lookup tables for estimating the cloud-top height (CTOP) and visible optical thickness of upper-tropospheric clouds by the infrared brightness temperature (TB) at 10.8 ?m (T11) and its difference from TB at 12 ?m (DT11-12) measured by geostationary satellites are developed (Hamada and Nishi 2010, JAMC). These lookup tables were constructed by regressing the cloud radar measurements by the CloudSat satellite over the infrared measurements by the Japanese geostationary multifunctional transport satellite MTSAT-1R and MTSAT-2. The calculated CTOP is available at http://database.rish.kyoto-u.ac.jp/arch/ctop/ since July 2005. A merit of this dataset is that standard deviations of measurements around the estimates were also available as an indicator of the ambiguity in the estimates. The data have good precision for tropical cirrus clouds that have large DT11-12 values and suitable for analyses of cloud systems with well-developed cirrus clouds. We made correction for the satellite view angle and can offer the data over almost all tropical regions where the satellites can observe (20S-20N, 80E-160W for MTSAT-1R and 85E-155W for MTSAT-2). We analyzed zonally elongated cloud band extending 3000 km around ITCZ. It was first tightly concentrated at the ITCZ latitude and then spread meridionally into the two parallel zonal cloud bands. They kept moving meridionally away even after the cumulonimbi that could make divergence wind were hardly seen around the ITCZ. This phenomenon attracted attention during January 1993, the intensive observation period (IOP) of the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Since there were not enough rainfall and cloud height information at that time, it was not clear why meridional separation starts simultaneously in the wide zonal region and what causes the continuous meridional separation over a day. In this study, we detected some typical cases in 2007, covered with our CTOP data. We examined detail of the separation with our CTOP data and Global Satellite Mapping of Precipitation (GSMaP; Kubota et al. 2007, IEEE Trans. Geosci. Remote Sens) data: precipitation estimation dataset made with microwave radiometers including Tropical Rainfall Measuring Mission/Microwave Imager (TRMM/TMI). We found that the separated cloud bands had little precipitation regions (larger than 1mm/hour) and CTOP was above 12 km. The facts show that the bands consist of the cirriform clouds passively advected by larger-scale wind. However, there are little active cumulus systems, which generally create horizontal divergence in the cirrus height, between and within the cloud bands, when examining GSMaP data and optical thickness estimation in the CTOP data. Though we do not have conclusive idea for this separation mechanism, one plausible candidate is a westward-moving equatorial trapped inertial gravity wave. It was observed around these cloud bands and can make meridional divergence without cumulus activity.

Nishi, N.; Hamada, A.; Ohigawa, M.; Shige, S.

2011-12-01

347

Radiation Pressure Modelling for Precise Orbit Determination of the Galileo IOV Satellites  

NASA Astrophysics Data System (ADS)

Four Galileo satellites are currently in orbit for In Orbit Validation (IOV) of the European Global Navigation Satellite System and are providing navigation signals. Precise orbits for these satellites are computed by several groups in the context of the Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS). MGEX currently makes available tracking data of a global network of more than 90 multi-GNSS receivers. Satellite Laser Ranging (SLR) tracking data indicate orbit modelling issues for the Galileo IOV satellites. Once-per-rev orbit errors depending on the Sun elevation above the orbital plane are also evidenced from apparent clock offset variations of the highly stable on-board hydrogen masers. Based on the analysis of clock corrections a variety of radiation pressure models for the Galileo IOV satellites are assessed and models with a significantly improved performance as compared to the standard models currently used in the community are highlighted.

Hugentobler, Urs; Montenbruck, Oliver; Steigenberger, -Peter

348

Analysis of Multi-Satellite Tracking Data of the Kaguya Satellites for Orbit and Gravity Field Determination  

NASA Astrophysics Data System (ADS)

The Kaguya spacecraft were launched from Tanegashima Space Center on September 14, 2007. Kaguya consists of three orbiters: a main orbiter in a low-altitude (100 km) circular polar orbit, and two sub-satellites (Rstar and Vstar) in elliptical orbits. The satellites were tracked by a variety of terrestrial based tracking systems: in addition to standard two-way Doppler and range tracking, there was 4-way Doppler tracking between Rstar and the main orbiter, providing the first tracking data of a satellite over the lunar far side, and there was same-beam differential VLBI tracking between the two sub-satellites, providing precise orbits for these satellites. The main orbiter was also equipped with a laser altimeter (LALT) to measure the topography of the Moon. At points where the ground tracks of different orbits intersect, these data can provide further constraints on the orbit of the main satellite in the form of crossovers, as essentially the same topography should be measured. This comprehensive data set between the satellites allows for a unique opportunity to evaluate the contribution of these tracking systems to orbit and gravity field determination. Precise orbits are important for geolocation of the topography and camera data, whereas the gravity field can be used for studies of the lunar interior. Here, we present the analysis of the combinations of these tracking data. The use of 4-way and same-beam differential VLBI data leads to large improvements in orbit precision of all satellites involved, where especially peaks in orbit overlap differences during edge-on periods are reduced. The use of the altimetry crossovers improves the orbit of the main satellite further, resulting in an orbit precision of in general less than 20 m. We have also used the full set of SELENE tracking data (including all 4-way and all S-band same-beam differential VLBI data), together with historical data, for gravity field determination. We show a lunar gravity field model with an improved orbit determination performance, especially for orbits over the deep far side. Finally, we use the improved gravity field model to investigate the determination of the lower degrees of the spherical harmonics expansion. These results thus show the benefits from having multiple spacecraft tracking for orbit and gravity field determination.

Goossens, S. J.; Matsumoto, K.; Kikuchi, F.; Liu, Q.; Hanada, H.; Lemoine, F. G.; Rowlands, D. D.; Ishihara, Y.; Jianguo, Y.; Araki, H.; Noda, H.; Namiki, N.; Iwata, T.

2010-12-01

349

Orbit Optimization and Scattering Coefficient Analysis for the Proposed GLORIA System  

NASA Technical Reports Server (NTRS)

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

Welch, Bryan

2004-01-01

350

Progress in developing a geostationary AMSU  

NASA Astrophysics Data System (ADS)

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

Lambrigtsen, Bjorn

2009-09-01

351

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

352

Constant Orbital Momentum Equilibrium Trajectories of a Gyrostat-Satellite  

NASA Astrophysics Data System (ADS)

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

VanDyke, Matthew Clark

353

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

Microsoft Academic Search

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

C. C. Chao; R. A Gick

2004-01-01

354

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

NASA Astrophysics Data System (ADS)

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

Ehrhorn, B.; Azari, D.

355

The National Polar-orbiting Operational Environmental Satellite System  

NASA Astrophysics Data System (ADS)

Over the last decade, the tri-agency Integrated Program Office (IPO), comprised of the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA), has been managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Once operational later this decade, NPOESS will replace NOAA's Polar-orbiting Operational Environmental Satellites (POES) and DoD's Defense Meteorological Satellite Program (DMSP) systems. The IPO, through its Acquisition and Operations contractor, Northrop Grumman, will launch NPOESS spacecraft into three orbital planes to provide a single, national system capable of satisfying both civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving the existing 'weather' satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - ocean, atmosphere, land, and the space environment. NPOESS will transform today's short-term, space-based ocean research missions into a sustained, operational ocean remote sensing observation program. Ocean measurements comprise one-fourth of the 55 user-validated requirements for geophysical measurements that will be made by NPOESS sensors. In 1997, the IPO initiated a robust sensor risk reduction effort for early development of the critical sensor suites and algorithms necessary to support NPOESS. In 2001, preliminary design efforts were completed for the last of five critical imaging/sounding instruments for NPOESS. Ocean requirements have directly and substantially 'driven' the design of three NPOESS sensors: the Visible/Infrared Imager Radiometer Suite (VIIRS); the Conical-scanning Microwave Imager/Sounder (CMIS); and the Altimeter. With these instruments, NPOESS will deliver higher resolution (spatial and temporal) and more accurate measurements of sea surface temperature (SST), ocean surface wind vectors/stress, ocean color and suspended matter, sea ice (edge motion, age, surface temperature, thickness), oceanic heat flux, significant wave height, and sea surface topography. Infrared and microwave measurements of sea surface temperature from VIIRS and CMIS, respectively, will be combined to produce 'all weather' SST products. VIIRS imagery and altimeter measurements will be used to derive ocean circulation parameters to meet monitoring requirements for both operational and research purposes. The advanced technology visible, infrared, and microwave imagers and sounders that will fly on NPOESS will deliver higher spatial and temporal resolution oceanic, atmospheric, terrestrial, climatic, and solar-geophysical data, enabling more accurate short-term weather forecasts and severe storm warnings and improved real-time monitoring of coastal and open ocean phenomena. NPOESS will also provide continuity of critical data for monitoring, understanding, and predicting climate change and assessing the impacts of climate change on seasonal and longer time scales. The NPOESS team is well along the path to creating a high performance, polar-orbiting satellite system that will be more responsive to user requirements, deliver more capability at less cost, and provide sustained, space-based measurements as a cornerstone of an Integrated Global Observing System.

Hoffman, C. W.; Mango, S.; Schneider, S.; Duda, J.; Haas, J.; Bloom, H.

2005-12-01

356

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

NASA Technical Reports Server (NTRS)

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

Velden, Christopher S.

1994-01-01

357

Estimating urban temperature bias using polar-orbiting satellite data  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

358

Spacecraft design project: Low Earth orbit communications satellite  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

359

Estimating Urban Temperature Bias Using Polar-Orbiting Satellite Data.  

NASA Astrophysics Data System (ADS)

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

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

1994-03-01

360

Parameter identification by a conjugate gradient method Application to the restoration of a satellite orbit  

NASA Astrophysics Data System (ADS)

A comparison is made of methods common for determining the orbital parameters of a satellite. The techniques all involve maximum likelihood estimates. The conjugate gradient method is shown to permit derivation of the maximum of the likelihood function. Attention is also given to the common roots of recursive least squares calculations and the Kalman filter. Comparisons are made between the effectiveness of the conjugate gradient method and the Kalman filter for calculating a satellite orbit from ground-based sightings of the satellite. The conjugate gradient method is demonstrably more robust for defining the orbit when the initial orbital parameters are not known. Sample calculations are also provided for acquisition of a satellite in nonoptimal conditions, and for projecting the orbit of the SPOT satellite after launch into a degraded orbit.

Aumasson, C.; Grimard, M.

361

Communications satellite systems capacity analysis  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

362

SPICE Module for the Satellite Orbit Analysis Program (SOAP)  

NASA Technical Reports Server (NTRS)

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

Coggi, John; Carnright, Robert; Hildebrand, Claude

2008-01-01

363

Surface Radar Studies of Rain Estimation in Correlation with Infrared and Visible Techniques of INSAT and Goes -e Geostationary Satellites  

Microsoft Academic Search

This study explores further the application of the radar reflectivity and the derivation of the empirical relationship linking the rainfall parameters to the radar observables reflectivity (Z), differential reflectivity (Z_{DR}) and attenuation (K), using exponential raindrop size distribution N(D). The IR data in the range of 10.5-12.5 mu m from INSAT-IB and 10.5-12.6 mu m from GOES-E geosynchronous satellites have

Aziz Ur-Rahman Malik

1992-01-01

364

The High-ORbit Ultraviolet-visible Satellite, HORUS  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

365

GBT Reveals Satellite of Milky Way in Retrograde Orbit  

NASA Astrophysics Data System (ADS)

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

2003-05-01

366

GOES-R satellite solar panels ready for space  

NASA Astrophysics Data System (ADS)

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

Wendel, JoAnna

2014-07-01

367

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

368

Circumnutations of Sunflower Hypocotyls in Satellite Orbit 1  

PubMed Central

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

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

1990-01-01

369

Scripting Module for the Satellite Orbit Analysis Program (SOAP)  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

370

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

371

The Geostationary Atmospheric Sounder (GAS)  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

372

Meteorological satellites  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

373

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

Microsoft Academic Search

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

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

1999-01-01

374

Aleksandar KOSTADINOV: Expected performance of Orbit Determination of the GALILEO Satellites  

E-print Network

Aleksandar KOSTADINOV: Expected performance of Orbit Determination of the GALILEO Satellites (completed Jänner 2003) In March 2002 the European Union decided to finance the GALILEO orbits (MEOs) at 23600 km altitude. The launch of the first GALILEO satellites can be expected

Schuh, Harald

375

Assessment of surface turbulent fluxes using geostationary satellite surface skin temperatures and a mixed layer planetary boundary layer scheme  

NASA Technical Reports Server (NTRS)

A method is presented for evaluating the fluxes of sensible and latent heating at the land surface, using satellite-measured surface temperature changes in a composite surface layer-mixed layer representation of the planetary boundary layer. The basic prognostic model is tested by comparison with synoptic station information at sites where surface evaporation climatology is well known. The remote sensing version of the model, using satellite-measured surface temperature changes, is then used to quantify the sharp spatial gradient in surface heating/evaporation across the central United States. An error analysis indicates that perhaps five levels of evaporation are recognizable by these methods and that the chief cause of error is the interaction of errors in the measurement of surface temperature change with errors in the assigment of surface roughness character. Finally, two new potential methods for remote sensing of the land-surface energy balance are suggested which will relay on space-borne instrumentation planned for the 1990s.

Diak, George R.; Stewart, Tod R.

1989-01-01

376

Orbit determination of the SELENE satellites using multi-satellite data types and evaluation of SELENE gravity field models  

Microsoft Academic Search

The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents\\u000a a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking\\u000a data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far\\u000a side, and of same-beam differential VLBI

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

2011-01-01

377

NASA Educational Briefs for the Classroom. Orbits of Bodies in Space  

NASA Technical Reports Server (NTRS)

The difference between an orbit and a revolution is explained and it is shown why space shuttle Columbia's period of revolution was longer than its orbital period. Parameters of orbits examined include apoapsis, periapsis, apogee, perigee, aphelion, perihelion, orbital plane, and inclination. Orbit velocity and duration, Newton's law of gravitation, and Kepler's three laws of motion are considered. The principles involved in geostationary satellites are also explored.

1982-01-01

378

A virtual environment for satellite modeling and orbital analysis in a distributed interactive simulation  

NASA Astrophysics Data System (ADS)

In response to the need for a more realistic, interactive, and immersive space simulation system, the Joint National Intelligence Defense Staff (JNIDS) has sponsored the development of the Satellite Modeler at the Air Force Institute of Technology (AFIT). The Satellite Modeler (SM) is a virtual environment (VE) application that allows analyst-users to enter a virtual near-Earth space environment and visualize realistic satellite models performing accurate orbital motion. The Satellite Modeler provides manipulation functions that allow a user to interact with multiple satellite models and satellite constellations. The system affords the user multiple vantage points within the environment to view satellites in orbit. It also functions as a network actor in a distributed simulation environment. The Satellite Modeler achieves accurate physical modeling of satellite motion by using the North American Air Defense (NORAD) Command SGP4 orbital model and associated orbital elements for satellites currently in orbit. System functionality is realized within an object-oriented framework and accessible through a graphical user interface (GUI). This thesis is the second of a three-year effort to create a three dimensional virtual environment for modeling and manipulating satellite objects.

Kunz, Andrea A.

1993-12-01

379

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

380

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

SciTech Connect

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

Menzel, P.; Prins, E.

1995-12-01

381

Long-term orbit perturbations of the Draim four-satellite constellations  

NASA Astrophysics Data System (ADS)

The long-term perturbation effects on the Draim four-stellite constellations with a common period are analyzed. The required orbit maintenance fuel consumption for offsetting these perturbations are estimated, and a strategy is presented for biasing the initial orbit elements to avoid costly stationkeeping maneuvers. The performance of the Draim four-satellite constellations in the presence of perturbations is compared with that of four geosynchronous satellites and four Molniya satellites.

Chao, C. C.

382

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

Microsoft Academic Search

Earlier studies conducted a The Aerospace Corporation discovered that the GPSt Block II satellites placed in disposal orbits can eventually, perhaps in 20 to 40 years, reenter into the operating constellation. This is because the disposal orbits, while circular initially, evolve int o orbits with significant eccentricity mostly as the result of sun-moon gravitational perturbations. Options of minimizing the eccentricity

C. Chao; R. Gick

2002-01-01

383

The orbits of the satellites of Mars from spacecraft and earthbased observations  

NASA Technical Reports Server (NTRS)

This article presents the results of a fit of a model of the Martian satellite orbits to earthbased and spacecraft-based observations. An assessment of the orbit accuracies is given and the orbits are compared with those obtained by previous investigators.

Jacobson, R. A.; Synnott, S. P.; Campbell, J. K.

1989-01-01

384

Orbit determination and prediction of GEO satellite of BeiDou during repositioning maneuver  

NASA Astrophysics Data System (ADS)

In order to establish a continuous GEO satellite orbit during repositioning maneuvers, a suitable maneuver force model has been established associated with an optimal orbit determination method and strategy. A continuous increasing acceleration is established by constructing a constant force that is equivalent to the pulse force, with the mass of the satellite decreasing throughout maneuver. This acceleration can be added to other accelerations, such as solar radiation, to obtain the continuous acceleration of the satellite. The orbit determination method and strategy are illuminated, with subsequent assessment of the orbit being determined and predicted accordingly. The orbit of the GEO satellite during repositioning maneuver can be determined and predicted by using C-Band pseudo-range observations of the BeiDou GEO satellite with COSPAR ID 2010-001A in 2011 and 2012. The results indicate that observations before maneuver do affect orbit determination and prediction, and should therefore be selected appropriately. A more precise orbit and prediction can be obtained compared to common short arc methods when observations starting 1 day prior the maneuver and 2 h after the maneuver are adopted in POD (Precise Orbit Determination). The achieved URE (User Range Error) under non-consideration of satellite clock errors is better than 2 m within the first 2 h after maneuver, and less than 3 m for further 2 h of orbit prediction.

Cao, Fen; Yang, XuHai; Li, ZhiGang; Sun, BaoQi; Kong, Yao; Chen, Liang; Feng, Chugang

2014-11-01

385

Time-Dependent Density Wave Theory for Co-orbital Satellites  

NASA Astrophysics Data System (ADS)

The standard theory of density waves in planetary rings assumes that the orbit of the perturbing satellite is on a fixed orbit. However, the co-orbital satellites, Janus and Epimetheus, trade orbits every four years. Cassini images of Saturn's rings record the time evolution of the density waves excited by these satellites. Ticareno et al. (Ap. J. 651: L65-L68, 2006) attempted to model the observations by assuming the steady-state density waves shift locations in the rings instantaneously when the co-orbital satellites trade orbits. They found that certain wave-like features are observed in the evanescent region of the wave that were not predicted by the steady state theory. We will present the results of a new time-dependent density wave theory that can model the perturbations by the co-orbital satellites during their orbital exchange. Similar to our previous result for temporally modulated density waves excited by the satellite, Pandora (Stewart and Sremcevic, DDA 2008), we find that the effective sound velocity in the wave plays an important role in propagating the time-dependent signal in the wave train. Comparisons with Cassini observations as well as predictions for the next co-orbital exchange event in January 2010 will be presented. This research was supported by NASA's Outer Planets Research Program.

Stewart, Glen R.

2009-05-01

386

Optimal resource allocation for low-earth orbit (LEO) satellite networks with multirate traffics  

Microsoft Academic Search

Similar to a mobile-user in the cell-based GSM, a satellite in a LEO system constantly circulates along its predesigned orbit. Satellites' movement causes their visibility change, and thus a user's call needs to be handed over among satellites from time to time. The handovers may occur frequently. Without handling those calls well, the system performance will degrade. This paper dealt

Kai-Wei Ke; Chii-Wei Tzeng

2002-01-01

387

Monitoring of Tropospheric Ozone from Backscattered Ultraviolet Measurements on Geostationary Platforms  

NASA Astrophysics Data System (ADS)

Ozone profiles, including tropospheric ozone, have been successfully retrieved from nadir-viewing backscattered ultraviolet radiances measured by the GOME and OMI instruments on sun synchronous polar-orbiting satellites. The retrievals have sufficient accuracy in the troposphere to see ozone perturbations caused by convection, biomass burning, anthropogenic pollution, stratosphere intrusion, and to track their transport spatiotemporally. The same technique can be applied to geostationary platforms to measure tropospheric ozone at high temporal resolution. From the geostationary platform, the viewing zenith angle is very large at high latitudes, as well as far to the west and to the east; the solar zenith angle is also very large near sunset or sunrise. These large zenith angles limit the sensitivity to ozone in the troposphere. We will perform a quantitative investigation of the spatiotemporal range where and when there is at least 1 piece of tropospheric ozone information for a geostationary satellite parking at 95W. Because the viewing geometry limitation can be mitigated with the use of a geosynchronous orbit, we will discuss the impact of this alternative orbit on the measurable spatiotemporal range. Since taking measurements down to short wavelengths (e.g., <300 nm) will complicate the instrument design and increase mission cost, we will optimize the start wavelength range so that tropospheric ozone information is kept while cost is reduced. In addition, we will investigate the effects of spectral resolution, signal to noise ratio, adding UV polarization and visible measurements on the tropospheric ozone sensitivity.

Liu, X.; Bhartia, P. K.; Chance, K.

2009-12-01

388

Satellite Power System (SPS) international agreements  

NASA Technical Reports Server (NTRS)

The problems in obtaining international agreements on geostationary orbit availability, microwave frequency allocations and microwave frequency standards for satellites transmitting solar power are considered. The various U.S. policy options, strategies and time frames with respect to key issues are analyzed.

Grove, S.

1978-01-01

389

Satellite Communications in the 1980's.  

ERIC Educational Resources Information Center

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

Usunier, Pierre

390

A Permanent Magnet Hall Thruster for Pulsed Orbit Control of Lunar Polar Satellites  

NASA Astrophysics Data System (ADS)

Future Moon missions devoted to Lunar surface remote sensing, for example, will require very fine and accurate orbit control. It is well known that Lunar satellites in polar orbits will suffer a high increase on the eccentricity due to the gravitational perturbation of the Earth. Without proper orbit correction the satellite lifetime will decrease and end up in a collision with the Moon surface. It is pointed out by many authors that this effect is a natural consequence of the Lidov-Kozai resonance. We studied different arcs of active lunar satellite propulsion, centered on the orbit apoapsis or periapsis, in order to be able to introduce a correction of the eccentricity at each cycle. The proposed method is based on an approach intended to keep the orbital eccentricity of the satellite at low values.

Silva Moraes, Brunno; Ferreira, José Leonardo; Soares Ferreira, Ivan; Cabo Winter, Othon; Cardozo Mourão, Décio

2014-05-01

391

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

NASA Technical Reports Server (NTRS)

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

Fuchs, A. J. (editor)

1979-01-01

392

Design of a Representative Low Earth Orbit Satellite to Improve Existing Debris Models  

NASA Technical Reports Server (NTRS)

This paper summarizes the process and methodologies used in the design of a small-satellite, DebriSat, that represents materials and construction methods used in modern day Low Earth Orbit (LEO) satellites. This satellite will be used in a future hypervelocity impact test with the overall purpose to investigate the physical characteristics of modern LEO satellites after an on-orbit collision. The major ground-based satellite impact experiment used by DoD and NASA in their development of satellite breakup models was conducted in 1992. The target used for that experiment was a Navy Transit satellite (40 cm, 35 kg) fabricated in the 1960 s. Modern satellites are very different in materials and construction techniques from a satellite built 40 years ago. Therefore, there is a need to conduct a similar experiment using a modern target satellite to improve the fidelity of the satellite breakup models. The design of DebriSat will focus on designing and building a next-generation satellite to more accurately portray modern satellites. The design of DebriSat included a comprehensive study of historical LEO satellite designs and missions within the past 15 years for satellites ranging from 10 kg to 5000 kg. This study identified modern trends in hardware, material, and construction practices utilized in recent LEO missions, and helped direct the design of DebriSat.

Clark, S.; Dietrich, A.; Werremeyer, M.; Fitz-Coy, N.; Liou, J.-C.

2012-01-01

393

ORION: A Supersynchronous Transfer Orbit mission  

NASA Technical Reports Server (NTRS)

ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

Walters, I. M.; Baker, J. F.; Shurmer, I. M.

1995-01-01

394

Geostationary Imaging Fourier Transform Spectrometer (GIFTS): science applications  

NASA Astrophysics Data System (ADS)

A revolutionary satellite weather forecasting instrument, called the "GIFTS" which stands for the "Geostationary Imaging Fourier Transform Spectrometer", was recently completed and successfully tested in a space chamber at the Utah State University's Space Dynamics Laboratory. The GIFTS was originally proposed by the NASA Langley Research Center, the University of Wisconsin, and the Utah State University and selected for flight demonstration as NASA's New Millennium Program (NMP) Earth Observing-3 (EO-3) mission, which was unfortunately cancelled in 2004. GIFTS is like a digital 3-d movie camera that, when mounted on a geostationary satellite, would provide from space a revolutionary four-dimensional view of the Earth's atmosphere. GIFTS will measure the distribution, change, and movement of atmospheric moisture, temperature, and certain pollutant gases, such as carbon monoxide and ozone. The observation of the convergence of invisible water vapor, and the change of atmosphe