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Last update: November 12, 2013.
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

Geostationary Satellite Orbit Analysis Program (OSOAP)  

Microsoft Academic Search

The paper describes a computer model which is capable of computing mutual interference among communications satellites in the geostationary satellite orbit. The model accesses a database of satellite orbital and system parameters and is composed of an interactive data retrieval element and an interference calculation element. The software package can support upwards of hundreds of satellite networks depending upon local

G. Hurt; H. Ng; H. Akima; C. Filippi

1986-01-01

3

A method of producing analytical orbit models for geostationary satellites  

Microsoft Academic Search

The general analytical expressions of satellite orbit perturbations are lengthly and complicated. However, considerable simplifications can be achieved for nearly geostationary satellites. Whereas the analytical form of the perturbations is derived by geometrical considerations, the coefficients are determined by multiple Fourier analysis. The result is a single formula representing the entire perturbation theory of nearly geostationary satellites terms of 'geostationary

M. Eckstein

1979-01-01

4

Geostationary communications satellite orbit utilization strategies for the 1980s  

NASA Astrophysics Data System (ADS)

Orbital congestion became apparent when the number of applications filed with the Federal Communication Commission (FCC) for 6/4 GHz orbital slots exceeded the number of slots available. In order to overcome this congestion, approaches must be studied for increasing the capacity of the geostationary orbit. In connection with an identification of the factors which affect geostationary orbit capacity, three types of capacity are introduced, including site capacity, service area capacity, and total capacity of the geostationary orbit. Attention is given to approaches for increasing the number of satellites in the geostationary orbit, the phased introduction of new technology, increased interference allocations from other satellites, methods for increasing the spectral efficiency by channel equipment design, the possibility to increase the spectral efficiency by antenna design and frequency reuse, procedures for increasing the available bandwidth, and the development of techniques for optimizing the placement of satellites serving different service areas.

Hedinger, R. A.

5

Technical Basis for the Geostationary Satellite Orbit Analysis Program (GSOAP) - Version 2.  

National Technical Information Service (NTIS)

The Geostationary Satellite Orbit Analysis Program (GSOAP) is computer software that analyzes system performance and mutual interference of communication satellites using the geostationary satellite orbit. Calculation of the CIR (carrier-to-interference r...

H. Akima

1985-01-01

6

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

NASA Astrophysics Data System (ADS)

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

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

1987-05-01

7

Lithium-ion battery design for the hybrid satellite in the geostationary orbit  

Microsoft Academic Search

The first hybrid satellite in the geostationary orbit in Korea is being developed by KARI (Korea Aerospace Research Institute) and ASTRIUM based on the EUROSTAR 3000 platform. The hybrid satellite accommodates multiple payloads of meteorological imager, geostationary ocean color imager, and the Ka band satellite communication payload into a single spacecraft platform. The energy storage function is required during launch

Ja Chun Koo; Sang Kon Lee; Sung Woong Ra

2009-01-01

8

A Method of Producing Analytical Orbit Models for Geostationary Satellites.  

National Technical Information Service (NTIS)

A simplified perturbation theory of nearly geostationary satellites is described. The analytical form of the perturbations is derived from geometrical considerations and the coefficients are determined using multiple Fourier analysis. The resulting single...

M. Eckstein

1979-01-01

9

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

Federal Register 2010, 2011, 2012, 2013

...Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit Space Stations AGENCY: Federal...Aircraft. FOR FURTHER INFORMATION CONTACT: Andrea Kelly, Satellite Division, International Bureau, FCC, (202)...

2013-03-29

10

Technical basis for the Geostationary Satellite Orbit Analysis Program (GSOAP), version 2  

Microsoft Academic Search

The Geostationary Satellite Orbit Analysis Program (GSOAP) is computer software that analyzes system performance and mutual interference of communication satellites using the geostationary satellite orbit. Calculation of the carrier-to-interference ratio margins is an essential part of GSOAP. It involves a (CIR) variety of technical problems, i.e., Earth-station and satellite antenna radiation patterns, radio wave propagation models, and related problems such

H. Akima

1985-01-01

11

The Photometric Brightness Variation of Geostationary Orbit Satellite  

NASA Astrophysics Data System (ADS)

Photometric observation is one of the most effective techniques for determining the physical characteristics of unknown space objects and space debris. In this research, we examine the change in brightness of the Communication, Ocean, Meteorological Satellite-1 (COMS-1) Geostationary Orbit Satellite (GEO), and compare it to our estimate model. First, we calculate the maximum brightness time using our calculation method and then derive the light curve shape using our rendering model. The maximum brightness is then calculated using the induced equation from Pogson's formula. For a comparison with our estimation, we carried out photometric observation using an optical telescope. The variation in brightness and the shape of the light curve are similar to the calculations achieved using our model, but the maximum brightness shows a slightly different value from our calculation result depending on the input parameters. This paper examines the photometric phenomenon of the variation in brightness of a GEO satellite, and the implementation of our approach to understanding the characteristics of space objects.

Seo, Haingja; Song, Yongjun; Lee, Yongseok; Oh, Youngseok

2013-09-01

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

GOES Data Collection System. GOES-2 Test Report (Geostationary Orbiting Environmental Satellite).  

National Technical Information Service (NTIS)

A series of engineering tests was performed on the Data Collection System (DCS) communications links through the Geostationary Orbiting Environmental Satellite (GOES 2) which was launched by NASA. The tests were conducted at the NOAA Command and Data Acqu...

1978-01-01

14

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

NASA Astrophysics Data System (ADS)

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.

1987-05-01

15

An expert system for geostationary orbit satellite breakdown analysis  

Microsoft Academic Search

Two prototypes of expert systems for breakdown diagnosis on synchronous orbit satellites are described. The first prototype monitors the attitude and orbit control system of the French Telecom 1 satellite. The second prototype monitors the Power Conditioning Subsystem (PCS) of the TDF1 satellite. Both prototypes are intended for use by operation engineers in flight control centers. Both systems use the

L. Gibet

1990-01-01

16

Orbital mission profile of geostationary satellites for HI launch vehicle payload  

Microsoft Academic Search

The planned orbital mission profile of the ETS-V satellite to be launched by the H-I launch vehicle is described. The ETS-V is a 550-kg class, three-axis stabilized geostationary satellite. A diagram of the typical ground trace and the transfer orbit and stations for the satellite is presented. The optimization of the injection orbit parameters, and the launch window of the

M. Horii; M. Kusanagi; K. Ueno; K. Izumida; M. Miyashita

1986-01-01

17

An expert system for geostationary orbit satellite breakdown analysis  

NASA Astrophysics Data System (ADS)

Two prototypes of expert systems for breakdown diagnosis on synchronous orbit satellites are described. The first prototype monitors the attitude and orbit control system of the French Telecom 1 satellite. The second prototype monitors the Power Conditioning Subsystem (PCS) of the TDF1 satellite. Both prototypes are intended for use by operation engineers in flight control centers. Both systems use the same expert system programming software generator EMICAT development tool.

Gibet, L.

1990-10-01

18

Performance and costs of Ariane and Space Shuttle in the transport of satellites to geostationary orbit  

Microsoft Academic Search

The volume and mass capacities, limitations, fuel types, and present and projected transport costs of the Ariane 1-4, STS (with inertial upper stage, payload-assist module, or apogee-boost motor), Titan, Atlas, and Delta systems for the commercial transport of satellites into geostationary transfer and\\/or geostationary orbit are listed in comparative tables and discussed in detail. It is shown that STS and

R. E. Lo

1983-01-01

19

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

Code of Federal Regulations, 2010 CFR

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

2009-10-01

20

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

21

Communication satellites in the geostationary orbit (2nd revised and enlarged edition)  

NASA Astrophysics Data System (ADS)

Regulatory, policy, and technical considerations pertaining to communications satellites in geostationary orbit (GSO) are addressed, and methods of dealing with the problem of interference that such satellites encounter are considered. An overview and historical perspective on GSO is given, and communication satellite sharing of the GSO is discussed. International and domestic orbit-spectrum policy is examined. Factors affecting orbit-spectrum utilization are addressed for both the homogeneous case and the nonhomogeneous case. The performance of analog and digital signals in an interference environment, interference cancellation-reduction techniques, and software for orbit-spectrum utilization studies are discussed.

Jansky, Donald M.; Jeruchim, Michel C.

22

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

23

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

24

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

25

Geostationary versus non geostationary orbits  

NASA Astrophysics Data System (ADS)

The issue of which satellite orbit, such as low earth orbit, medium earth orbit, highly elliptical orbit, geosynchronous orbit, etc., is best for a particular telecommunications role is not always straightforward. The technical, operational, financial, service, and reliability considerations must all be carefully assessed and detailed trade-off analysis undertaken. This article provides in some detail the type of methodology that can be utilized to conclude which particular set of orbital parameters would seem to be optimum for various missions. Ironically, many of the trade-off considerations today are similar to those some 30 years ago when the field of satellite communications was getting started. One major difference today is that satellite launch and operation is much more reliable. The general methodology presented here should be adaptable to addressing almost any proposed satellite system design and its optimum deployment.

Pritchard, Wilbur

26

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

Federal Register 2010, 2011, 2012, 2013

...categories address the satellite industry. The...category has a small business size...the majority of Satellite Telecommunications firms are small entities that...wireless firms are small...Categories (Except Satellite)'';...

2010-04-05

27

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

Federal Register 2010, 2011, 2012, 2013

...Geostationary-Orbit Space Stations AGENCY...two-way in-flight broadband services...passengers and flight crews aboard commercial airliners and...geostationary-orbit (GSO) space stations operating...Earth-to-space) band shall...radiation. While in flight there is...

2013-03-08

28

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

29

Performance and costs of Ariane and Space Shuttle in the transport of satellites to geostationary orbit  

NASA Astrophysics Data System (ADS)

The volume and mass capacities, limitations, fuel types, and present and projected transport costs of the Ariane 1-4, STS (with inertial upper stage, payload-assist module, or apogee-boost motor), Titan, Atlas, and Delta systems for the commercial transport of satellites into geostationary transfer and/or geostationary orbit are listed in comparative tables and discussed in detail. It is shown that STS and Titan 34D alone can provide service in the heavy-object (up to 5000 kg in the 1990's) class, that Ariane 1 and 3 cannot compete with STS in the lower weight classes as long as STS is subsidized, that Ariane 4 may be competitive with STS in the 2000-3000-kg range if no liquid-fueled apogee-perigee system exists for the STS inertial-upper-stage mode, and that the Soviet Proton system might be competitive with both STS and Ariane if it is really made available commercially in 1988 as planned.

Lo, R. E.

1983-11-01

30

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

Microsoft Academic Search

Many severe meteorological events develop at short time scales. The availability of effective rain-rate nowcasting techniques is valuable for Civil Protection purposes. Neural network based nowcasting techniques, exploiting satellite data, have been proven to be more accurate than conventional techniques. Several rain retrieval techniques have been proposed on the basis of multi-satellite imagery, exploiting passive sensor measurements acquired by Geostationary-Earth-Orbit

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

2009-01-01

31

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

32

Short course on ground operations systems for geostationary satellites: Orbit maneuver programs (Symphonie)  

Microsoft Academic Search

The orbit programs which have been used for injection and positioning and which are now used for stationkeeping of Symphonie satellites A and B are described briefly: apogee maneuver; orbit coarse corrections; orbit fine corrections; station keeping; mission analysis; and orbit determination. Selections from the Symphonie flight model 2 mission report on transfer and positioning phase are annexed.

A. Leibold

1976-01-01

33

Geostationary Satellite Data  

NSDL National Science Digital Library

This site, hosted by the Global Hydrology and Climate Center, a US National Aeronautics and Space Administration research center, provides real time images of the earth. Images are available for five regions: North America (1km); North and South America, Atlantic, and East Pacific (32km); Hawaii, Pacific Ocean and North America (32km); Japan, Australia, West Pacific, and Asia (32km); and a global geostationary satellite composite (56km). Users have the option of zooming in on a selected region of the image. Java based image animations are also available. Data for the images are obtained from three different satellites, GOES-8, GOES-9, and GMS-5. Images are updated every 30 minutes.

34

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

35

Tropospheric ozone measured in the thermal infrared: from polar orbiting satellites towards geostationary platforms (Invited)  

NASA Astrophysics Data System (ADS)

Monitoring atmospheric composition from geostationary orbit (GEO) in the thermal infrared (TIR) will provide data for a wide variety of users, from meteorology and climate to air quality applications. This talk will present results from a French-German consortium (LISA Creteil, CNRS - Meteo France Toulouse, KIT - IMK Karlsruhe) concerning air quality monitoring from GEO, with particular emphasis on instrument requirements and on the impact of such data on chemical models (MOCAGE, CHIMERE), based on a dedicated Observing System Simulation Experiment (OSSE) for CO and tropospheric O3. We will demonstrate the potential of TIR measurements for monitoring tropospheric O3 using data from the IASI instrument (focusing on Europe and megacities in China), and discuss some technical aspects based on instrument development at IMK, in particular concerning 2D-array detectors for passive atmospheric sounding in the TIR.

Orphal, J.; Flaud, J.; Dufour, G.; Eremenko, M.; Keim, C.; Bergametti, G.; Foret, G.; Beekmann, M.; Höpfner, M.; von Clarmann, T.; Friedl-Vallon, F.; Kleinert, A.; Attie, J.; Claeyman, M.; Peuch, V.; El Amroui, L.; Massart, S.; Piacentini, A.; Cantie, R.; Pasternak, F.

2009-12-01

36

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

37

Geostationary Orbital Estimation Using a Kalman Filter.  

National Technical Information Service (NTIS)

The ability of a sequential Kalman filter to predict a geostationary and an approximately geostationary orbit is assessed by comparison with the corresponding orbits predicted by a least-squares batch estimator. Prior to performing this comparison, the pe...

G. B. Sincarsin

1986-01-01

38

Geostationary Satellite Server  

NSDL National Science Digital Library

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

39

Ionospheric Imaging from Geostationary Orbit  

Microsoft Academic Search

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

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

2001-01-01

40

Ionospheric Imaging from Geostationary Orbit  

NASA Astrophysics Data System (ADS)

An ultraviolet imager is under development to image the ionosphere and thermosphere from geostationary orbit. The instrument will consist of two telescopes, one with a filter wheel to measure the atomic oxygen airglow emission at 130.4 nm and 135.6 nm and molecular nitrogen Lyman-Birge-Hopfield bands near 142.5 nm. The second telescope will image the atomic oxygen ion resonance multiplet at 83.4 nm. Both telescopes will have a field of regard of 1.5 degrees with resolutions of 0.01 degrees providing spatial coverage of 1500 km x 1500 km with a resolution of 10 km x 10 km. The telescopes will be mounted to a two-axis gimbal to image various regions of the disk and limb of the Earth. This instrument is tentatively planned to fly aboard an Air Force Space Test Program satellite in 2005. The primary science goals of the experiment are to image the nightside ionosphere using measurements of the OI 135.6 nm nightglow produced from radiative recombination of electrons with oxygen ions. These observations will be used to study the variability and dynamics of ionospheric irregularities. Secondary objectives include measurement of vertical profiles of electron density at night on the limb of the Earth and measurement of dayside oxygen ion profiles using the 83.4 nm resonant line. Additional objectives include: measurement of the dayside limb profiles of neutral density; studies of thermospheric heating and geomagnetic storms using observations of disk ratios of oxygen to nitrogen; studies of the morphology of the equator-ward edges of the aurora. It is anticipated that nightside ionospheric images can be obtained within 100 to 1000 seconds to allow high time resolution studies of the space weather effects in the ionosphere.

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

2001-05-01

41

Geostationary satellite imaging spectrometry for GEOSS: importance and expected benefits  

Microsoft Academic Search

Satellite infrared hyperspectral instruments provide atmospheric soundings with high spatial resolution. Already implemented aboard polar orbiting satellites, these instruments have provided data that are proving to improve greatly global Numerical Weather Prediction (NWP). When implemented aboard geostationary satellites as imaging spectrometers, even greater impacts on global NWP are expected from their capability to observe vertically resolved cloud and water vapor

W. Smith Sr.; S. Mango

2009-01-01

42

A preliminary study on dead geostationary satellite removal  

Microsoft Academic Search

The collision between satellites IRIDIUM 33 and COSMOS 2251 indicated that the clash of two on-orbit satellites was becoming\\u000a an inevitable reality. Our calculation with the two-line orbit element by NORAD showed that some two geostationary satellites\\u000a had approached very close in July 2009. Therefore, more attention should be given to avoid such collisions. This paper analyzes\\u000a the orbital long-term

YuHeng Li; KaiZhong Yang; ChengSheng Shan; Dan Luo; Hui Guan; Jun Zheng; Hong Cheng; Li Man

2010-01-01

43

Frequent Rain Observation From Geostationary Satellite  

NASA Astrophysics Data System (ADS)

The target 3-h observing cycle of GPM will meet requirements from Global NWP and, to a large extent, Regional NWP; and be supportive of VIS/IR-derived rain estimates from geostationary satellites for the purpose of Nowcasting. MW rain observation from geostationary orbit at, say, 15 min intervals, would fully meet Regional NWP requirements and have greatest impact on Nowcasting: but this implies either unprac- tically large antennas or unacceptably coarse resolution. Concepts to overcome this problem have been developed in the US within the study called GEM (Geostationary Microwave Observatory), and now there is in Europe a proposal for a demonstration satellite submitted to ESA as GOMAS (Geostationary Observatory for Microwave Atmospheric Sounding). To overcome the problem of resolution, use of Sub-mm fre- quencies is envisaged: e.g., at 425 GHz, a 10-km resolution at nadir would require a 3-m antenna. The observing principle is based on the use of absorption bands of oxygen (54, 118 and 425 GHz) and of water vapour (183 and 380 GHz). Narrow- bandwidths channels are implemented (for a total of about 40 in the five bands) so as to observe the full profile of temperature and water vapour. Profiles from different bands are differently affected by liquid and ice water of different drop size, and fi- nally by precipitation. Simultaneous retrieval of temperature/humidity profiles, cloud liquid/ice water (total-columns and gross profile) and precipitation rate is in principle possible, and partially demonstrated by several airborne MW/Sub-mm instruments. To transfer this demonstrations in the geostationary orbit, the problem of radiometric sensitivity (additional to that one of the antenna size) has to be solved. With current technology, it is feasible to get sufficient accuracy if scan is limited to about 1/12 of the Earth disk, which is sufficient to abundantly cover Europe, the Mediterranean and Eastern Atlantic. The imaged area can be moved everywhere within the disk, and the satellite itself can migrate along the equator to perform experiments from the Ameri- can continent to the Indian Ocean. As an example, the GOMAS concept (capitalising on the GEM concept) will be illustrated, for a relatively small satellite capable of ob- serving, each 15 min: temperature profile (30 km resolution), water vapour profile and cloud liquid/ice water total-columns or gross profile (20 km resolution), and precipita- tion rate (10 km resolution). Challenging aspects exist (e.g., active control of antenna deformations, simultaneous retrieval algorithm implying accurate cloud modelling, etc.), but it is felt that the satellite could be launched in the 2007-2009 timeframe.

Bizzarri, B.; Gomas Science Team

44

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

45

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

46

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

47

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

48

Observations of geostationary satellites at Helwan Observatory.  

NASA Astrophysics Data System (ADS)

Conditions and possibility of photographic observations of geostationary satellites by camera AFU-75 at Helwan Observatory are shown. 39 positions for 13 satellites are given, according to the results of observations on October 15, 1985.

Bakhtigaraev, N. S.; Baghos, B. B.; Towadrous, M. J.; Hilaly, Y. E.

49

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

NASA Astrophysics Data System (ADS)

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

Huang, F.

2010-12-01

50

Geostationary Meteorological Satellite5 (GMS-5)  

Microsoft Academic Search

This paper describes mission features and development of the Geostationary Meteorological Satellite-5 (GMS-5). The purpose of GMS series is the improvement of Japan's meteorological services and the development of meteorological satellite technology. The satellites have been used for the World Weather Watch (WWW) program planned by the World Meteorological Organization (WMO). The first satellite in this series was launched into

Koichi Kimura; Hideo Sakabe; Takao Suzuki; Motoi Okawara

1992-01-01

51

Geostationary Operational Environmental Satellite (GOES) Gyro Temperature Model.  

National Technical Information Service (NTIS)

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 measurin...

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

1996-01-01

52

European small geostationary communications satellites  

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

53

Geostationary Operational Environmental Satellite (GOES) mission profile  

Microsoft Academic Search

The GOES mission profile used to achieve geostationary orbit following separation from the Delta launch vehicle is described. The mission profile was constrained by the solid-propellant apogee kick motor which was undersized relative to the spacecraft weight. The resulting deficiency in delivered delta-V had to be made up by the spacecraft hydrazine propulsion system. The mission profile which best utilizes

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

1986-01-01

54

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

55

A seminumerical procedure for the calculation of geostationary orbit perturbations caused by the sun and the moon  

Microsoft Academic Search

The general analytical expressions of lunar-solar perturbations on satellite orbits are very lengthy and complicated. In order to take advantage of possible simplifications in the special case of geostationary orbits, a semi-numerical method was applied to develop a perturbation theory for nearly geostationary satellites. Whereas the analytical form of the perturbation terms can be derived by geometrical considerations, the coefficients

M. C. Eckstein

1977-01-01

56

Study of Orbit/Frequency Utilization for Satellite Broadcasting, Part 1.  

National Technical Information Service (NTIS)

The technical procedures for determining the effective orbit/frequency utilization for a geostationary broadcasting satellite, different from those of a geostationary communications satellite are described. The factors and procedures that affect the orbit...

E. Sawabe J. Majima J. Shimaoka M. Matsushita Y. Masuko

1971-01-01

57

Multicolor photometry of geostationary satellites  

Microsoft Academic Search

Photometric observations of three geosynchronous satellites in the B, V, and R color bands obtained with an air-cooled TV detector at the coudefocus of the 50-cm MTM-500 telescope at the Crimean Astrophysical Observatory on August 15-22, 1982, are reported. B, V, R, B-V, and V-R curves are shown for each satellite, and the color indices are found to be about

A. N. Abramenko; E. P. Pavlenko; V. V. Prokofeva; S. A. Severnyj; M. A. Smirnov

1983-01-01

58

Integration of Total Suspended Matter data from geostationary and polar-orbiting satellites over the North Sea using DINEOF  

NASA Astrophysics Data System (ADS)

Total Suspended Matter (TSM) from the SEVIRI and MODIS sensors are analysed using DINEOF (Data INterpolating Empirical Orthogonal Functions), an EOF-based technique to reconstruct missing data. The complementary nature of geostationary and polar data, with different spatial and temporal resolutions, is used in this work to combine these two data sets into a unique estimate of the North Sea TSM. The technique to achieve the merging is based on DINEOF, and consists on estimating a first EOF basis using the polar TSM data, which is used in a second step for the merging procedure. The merging analysis is based on the formalism of optimal interpolation, but an important difference is that the error covariance is not parametrized a priori using an analytical expression, but expressed using the spatial EOF basis calculated by DINEOF. This EOF basis represents more realistically the complex variability of the TSM data sets than the parametric covariance used in most optimal interpolation applications. Preliminary results will be shown demonstrating the possibilities of this approach. Given the high temporal and spatial resolution of the final TSM dataset, an analysis of tidal dynamics in the North Sea and their influence in TSM will be presented.

Alvera-Azcárate, Aida; Barth, Alexander; Vanhellemont, Quinten; Ruddick, Kevin; Beckers, Jean-Marie

2013-04-01

59

European small geostationary communications satellites  

Microsoft Academic Search

Hispasat Advanced Generation 1 (HAG1) is the first satellite using the SGEO platform, which is under the development in the ESA Artes-11 program. Since the last presentation in the IAC 2007, a European industrial consortium led by OHB has completed the mission and spacecraft design. The platform Preliminary Design Review has been carried out in May 2008. The customer for

Wei Sun; Frank Ellmers; Andreas Winkler; Herbert Schuff; Manuel Julián Sansegundo Chamarro

2011-01-01

60

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

61

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

62

Propellant gaging for geostationary satellites  

NASA Astrophysics Data System (ADS)

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

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

1986-06-01

63

Local Oscillator Distribution Using A Geostationary Satellite  

NASA Astrophysics Data System (ADS)

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 uplink and downlink capacity at 14 14.5 GHz and 11.7 12.2 GHz, respectively. 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 300 MHz 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 3 ps for integration times ranging from 1 to 2000 s. For integration times greater than 500 s, 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 then, the cost of both leased satellite bandwidth and the Ku-band ground equipment has dropped substantially and the performance of various components has improved. An important factor is the availability of narrow bands which can be leased on a communications satellite. We lease three 100 kHz bands at approximately one hundredth the cost of a full 36 MHz-wide transponder. Further tests of the system using terminals separated by large distances and comparison tests with two hydrogen masers and radio interferometry of astronomical objects are needed.

Bardin, J.; Weinreb, S.; Bagri, D.

2004-06-01

64

Azimuthal propagation and frequency characteristic of compressional Pc 5 waves observed at geostationary orbit  

Microsoft Academic Search

Energetic particle data from the 1977-007 and 1979-053 satellites and magnetic field data from the GOES 2 and 3 satellites have been used to study eight compressional Pc 5 wave events observed at geostationary orbit during 1979. All the events occurred on the dayside, and most of them were observed during the recovery phase of a geomagnetic storm. By using

Kazue Takahashi; Paul R. Higbie; Daniel N. Baker

1985-01-01

65

A Seminumerical Procedure for the Calculation of Geostationary Orbit Perturbations Caused by the Sun and the Moon.  

National Technical Information Service (NTIS)

A simplified semi-numerical perturbation method was developed for the special case of nearly geostationary satellites for orbits perturbed by the Sun and Moon. Whereas the analytical form of the perturbation terms can be derived from geometrical considera...

M. C. Eckstein

1978-01-01

66

Reduced domestic satellite orbit spacing  

NASA Astrophysics Data System (ADS)

The demand for services provided by communications satellites in geostationary orbit is growing, and problems arise with respect to the required increase in capacity. One approach for providing such an increase involves the employment of more satellites operating at smaller orbital spacings. The present investigation is concerned with the results of technical studies conducted by the Federal Communications Commission (FCC) to determine the feasibility of reducing orbital spacings between U.S. 'domestic fixed satellites' (domsats). Attention is given to details regarding the usable orbital arc, an adjacent satellite interference model, antenna sidelobe patterns, a single entry analysis, a 4/6 GHz aggregate analysis, results for the 4/6 GHz bands, results for the 12/14 GHz bands, data services, voice services, video reception, and high power spot beams.

Sharp, G. L.

67

A universal on-orbit servicing system used in the geostationary orbit  

NASA Astrophysics Data System (ADS)

The geostationary orbit (GEO), a unique satellite orbit of the human beings, is a very precious orbit resource. However, the continuous increasing of GEO debris makes the GEO orbit more and more crowded. Moreover, the failures of GEO spacecrafts will result in large economic cost and other bad impacts. In this paper, we proposed a space robotic servicing system, and developed key pose (position and orientation) measurement and control algorithm. Firstly, the necessity of orbit service in GEO was analyzed. Then, a servicing concept for GEO non-cooperative targets was presented and a universal space robotic servicing system was designed. The system has a 2-DOF docking mechanism, a 7-DOF redundant manipulator and a set of stereo vision, in addition to the traditional subsystems of a spacecraft. This system can serve most existing satellites in GEO, not requiring specially designed objects for grappling and measuring on the target. The servicing contents include: (a) visual inspecting; (b) target tracking, approaching and docking; (c) ORUs (Orbital Replacement Units) replacement; (d) Malfunctioned mechanism deploying; (e) satellites life extension by taking over its control, or re-orbiting the abandoned satellites. As an example, the servicing mission of a malfunctioned GEO satellite with three severe mechanical failures was designed and simulated. The results showed the validity and flexibility of the proposed system.

Xu, Wenfu; Liang, Bin; Li, Bing; Xu, Yangsheng

2011-07-01

68

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

NASA Astrophysics Data System (ADS)

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

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

69

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

Microsoft Academic Search

A geostationary satellite has reportedly failed during its orbit raising maneuvers from the GTO to its final stationary ring. It was felt that the failure was possibly caused by differential propellant rates of flow from the symmetrically placed pair of liquid tanks on either side of the center of mass. Alternatively even the initial fixed center-of-mass offset could have led

Krishna Kumar; Sanjay Singh

2002-01-01

70

Operational calibration of Geostationary Operational Environmental Satellite8 and -9 imagers and sounders  

Microsoft Academic Search

We describe the operational in-orbit calibration of the Geostationary Operational Environmental Satellite (GOES)-8 and -9 imagers and sounders. In the infrared channels the calibration is based on observations of space and an onboard blackbody. The calibration equation expresses radiance as a quadratic in instrument output. To suppress noise in the blackbody sequences, we filter the calibration slopes. The calibration equation

Michael Weinreb; Michael Jamieson; Nancy Fulton; Yen Chen; Joy Xie Johnson; James Bremer; Carl Smith; Jeanette Baucom

1997-01-01

71

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

Microsoft Academic Search

After movement of the first Meteosat Second Generation (MSG) satellite to 3.4 degree West by end of January 2004, the satellite has been renamed Meteosat-8 and the system has been declared fully operational. Meteosat-8 is now the primary European source of geostationary observations over Europe and Africa, as the first in a series of four satellites expected to deliver operational

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

2004-01-01

72

A program description of orbit-prints: Contours of power density at the geostationary orbit  

Microsoft Academic Search

A computer program is described which calculates the contours of terrestrial-emitter power density measured at or near the geostationary orbit. The program calculates the power density for an array of points located on the inside surface of a sphere described by the geostationary orbit. The theory and calculations used assumed free-space propagation. The geometry allows for arbitrary aiming of the

W. A. Kissick; D. N. Rebol

1977-01-01

73

Flow Analysis of Cloud Images from Geostationary Satellites  

Microsoft Academic Search

Geostationary satellites are a valuable source of rain- fall information due to the availability of a global view of clouds at an acceptable spatial and temporal resolution. However to retrieve the information from the satellite im- ages is a significant challenge. For example, precipita- tion peaks while the cloud area is rapidly growing and reduces at the time of maximum

Aimamorn Suvichakorn; Adrian R. Tatnall

74

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

Microsoft Academic Search

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

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

1993-01-01

75

Local orbital debris flux study in the geostationary ring  

NASA Astrophysics Data System (ADS)

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

Anderson, Paul V.; Schaub, Hanspeter

2013-06-01

76

Geostationary Satellites: Ideal Platforms for Tropospheric Chemistry Studies  

Microsoft Academic Search

The use of a geostationary platform is optimal for studying tropospheric chemistry processes which are highly variable both spatially and temporally. Instruments in low earth orbit, on the other hand, pass over the same portion of the planet no more than once per day, resulting in poor inference of processes that occur on time scales of minutes or hours, characteristic

J. Fishman

2001-01-01

77

Use of Geostationary Satellite Images for Interactive Meteorological Analysis  

Microsoft Academic Search

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

Johan van Heerden

1984-01-01

78

Non-resolved detection of objects performing On Orbit Servicing in Geostationary orbit  

NASA Astrophysics Data System (ADS)

On Orbit Servicing (OOS) of geostationary (GEO) satellites represents a new robotic space mission paradigm which could extend the life of existing satellites and reduce the rate of space debris generation. This mission type poses unique challenges for traditional optical space surveillance sensors. As the satellites perform close proximity operations, a distant observer sees the two objects as a single point source on a CCD (Charged Couple Device) as the objects’ angular separations, as viewed from a distant observer, are much smaller than the point source size of a typical space surveillance instrument. This analysis explores the unforced relative motion flight of a servicer satellite about its client GEO satellite with separations of 100 meters or less. Tools developed to address the physical and optical reflectance characteristics of this kind of mission type along with example light curves for diffuse optical reflections from both satellites performing OOS are presented. These tools create synthetic light curve data to permit future testing of light curve inversion and signal separation as a means to infer the relative motion of a secondary object about a GEO satellite.

Scott, R.; Ellery, A.; Levesque, M.

2011-09-01

79

Viking satellite orbit determination  

Microsoft Academic Search

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

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

1977-01-01

80

Interferometric Imaging of Geostationary Satellites: Signal-to-Noise Considerations  

NASA Astrophysics Data System (ADS)

Geostationary satellites are generally too small to image at high resolution with conventional single-dish telescopes. Obtaining many resolution elements across a typical geostationary satellite body requires a single-dish telescope with a diameter of 10’s of m or more, with a good adaptive optics system. An alternative is to use an optical/infrared interferometer consisting of multiple smaller telescopes in an array configuration. In this paper and companion papers1, 2 we discuss the performance of a common-mount 30-element interferometer. The instrument design is presented by Mozurkewich et al.,1 and imaging performance is presented by Schmitt et al.2 In this paper we discuss signal-to-noise ratio for both fringe-tracking and imaging. We conclude that the common-mount interferometer is sufficiently sensitive to track fringes on the majority of geostationary satellites. We also find that high-fidelity images can be obtained after a short integration time of a few minutes to a few tens of minutes.

Jorgensen, A.; Schmitt, H.; Mozurkewich, D.; Armstrong, J.; Restaino, S.; Hindsley, R.

2011-09-01

81

A global Video-on-Demand Architecture Based on a Novel Constellation Composed of Quasi-Geostationary Satellites  

Microsoft Academic Search

ó Satellite networks are going to play an indispensable role in the deployment of ubiquitous broadband multimedia systems. In this context, this paper considers a recently-proposed satellite constellation composed of Quasi GeoStationary Orbit (Quasi-GSO) satellites to provide a global and cost-effective Video-on-Demand (VoD) service. The main advantages of the constellation consist in its ability to provide global coverage with a

Tarik Taleb; Abbas Jamalipour; Nei Kato; Yoshiaki Nemoto

2005-01-01

82

Many uses of the geostationary operational environmental satellite-10 sounder and imager during a high inclination state  

Microsoft Academic Search

Geostationary Operational Environmental Satellite (GOES)-10 was the National Oceanic and Atmospheric Administration's (NOAA) operational GOES-West satellite for approximately eight years until it was retired as an operational satellite due to an ever increasing inclination in its orbit. Since its retirement, GOES-10 has been used for a number of applications, such as, special 1-minute imagery over parts of North America during

Timothy J. Schmit; Robert M. Rabin; A. Scott Bachmeier; Jun Li; Mathew M. Gunshor; Henry Steigerwaldt; Anthony J. Schreiner; Robert M. Aune; Gary S. Wade

2009-01-01

83

Devising geodetic satellite orbits  

Microsoft Academic Search

In the present paper, an intermediate theory of satellite motion, developed within the framework of the problem of six fixed centers with allowance for the influence of eight zonal harmonics of the geopotential, is applied to the analysis of quasi-geosynchronous and heliosynchronous orbits of geodetic satellites. Expressions for selecting nominal parameters for such orbits are proposed.

E. L. Lukashevich

1979-01-01

84

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

Microsoft Academic Search

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

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

2004-01-01

85

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.

86

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

Code of Federal Regulations, 2010 CFR

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

2009-10-01

87

Positioning determination and communications using two geostationary satellites  

NASA Astrophysics Data System (ADS)

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

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

1992-07-01

88

Distinguishing the populations of natural meteoroids and space debris by GORID in geostationary orbit  

Microsoft Academic Search

The Geostationary Orbit Impact Detector, GORID, is a dust impact plasma detector flying aboard the Russian Express-2 telecommunications spacecraft in geostationary orbit. The detector is the flight spare instrument of the successful Ulysses interplanetary dust detector which has contributed major results such as the detection of interstellar dust within our solar system. GORID is an active sensor, returning time resolved

J. P. Schwanethal; N. McBride

2001-01-01

89

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

Microsoft Academic Search

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

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

90

Modeling and simulation of an orbit controller for a communication satellite  

Microsoft Academic Search

It is of critical importance to control the altitude of a satellite especially one used for worldwide communications in a geo-stationary orbit. The objective of this work is to evolve a design based on modeling and simulation of an orbit controller for a satellite orbiting into a circular orbit. This involves a good understanding of the system dynamics. Once a

Muhammad Afzaal Malik; Ghazanfar Abbas Zaidi; Iyaz Aziz; Shahab Khushnood

2001-01-01

91

A Program Description of 'Orbit - Prints': Contours of Power Density at the Geostationary Orbit.  

National Technical Information Service (NTIS)

The report describes a computer program which calculates the contours of terrestrial-emitter power density measured at or near the geostationary orbit. The program calculates the power density for an array of points located on the inside surface of a sphe...

W. A. Kissick D. N. Rebol

1977-01-01

92

Surface solar radiation from geostationary satellites for renewable energy  

NASA Astrophysics Data System (ADS)

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

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

93

Operational evaluations of navigation through measurements of distance from geostationary satellites  

Microsoft Academic Search

Maritime and aerial navigation systems based on the determination of distance from geostationary satellites are proposed. Analytic and geometric considerations are cited in developing the position fixing procedure; the use of particular cartographic projections suited to the method is also required. An error analysis for sample position determinations obtained by reference to two geostationary satellites is presented.

N. Petronzi

1975-01-01

94

Los Alamos energetic particle sensor systems at geostationary orbit  

SciTech Connect

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

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

1985-01-01

95

Detection of a geostationary satellite with the Navy Prototype Optical Interferometer  

Microsoft Academic Search

We have detected a satellite via optical interferometry for the first time, using a 16 m baseline of the Navy Prototype Optical Interferometer (NPOI) to observe the geostationary communications satellite DirecTV-9S during the \\

J. T. Armstrong; R. B. Hindsley; H. R. Schmitt; F. J. Vrba; J. A. Benson; D. J. Hutter; R. T. Zavala

2010-01-01

96

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

SciTech Connect

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

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

2012-10-01

97

Relativistic electron flux forecast at geostationary orbit using Kalman filter based on multivariate autoregressive model  

NASA Astrophysics Data System (ADS)

The relativistic electron population at MeV energy in the Van Allen radiation belts at geostationary orbit largely varies in association with solar wind disturbances. To provide alerts of possible satellite malfunctions due to deep-dielectric charging during relativistic electron enhancements, the National Institute of Information and Communications Technology, Japan, developed an algorithm to forecast daily >2 MeV electron flux variations at geostationary orbit using a multivariate autoregressive model. We examined model accuracy by using solar wind speed, north-south component of the magnetic field, and dynamic pressure by inputting them as explanatory variates. The results showed that a combination of all three variates was most effective in reducing the prediction error. We focus here on the four-variate autoregressive model and handle it using the Kalman filter. The time evolution of the forecast is given by the conditional normal distribution: the peak value of forecast probability and the error range. The error range estimation is useful for users who utilize forecasts for operation of the satellites. We investigated the prediction efficiency of +1 day forecasts by evaluating forecast and observation data for a whole solar cycle (1999-2008) every 2 years. The prediction efficiency maintained at more than 69% throughout the solar cycle, although it depends on the phase of the cycle. Comparisons of the prediction efficiencies revealed that our model exhibited the best performance of conventional forecast models, particularly in solar active periods.

Sakaguchi, K.; Miyoshi, Y.; Saito, S.; Nagatsuma, T.; Seki, K.; Murata, K. T.

2013-02-01

98

Potential for calibration of geostationary meteorological satellite imagers using the Moon  

USGS Publications Warehouse

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

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

2005-01-01

99

Spectroscopic Observations of Geo-Stationary Satellites Over the Korean Peninsula  

NASA Astrophysics Data System (ADS)

Low resolution spectroscopic observations of geo-stationary satellites over the Korean peninsula have been carried out at the KyungHee Optical Satellite Observing Facility (KOSOF) with a 40cm telescope. We have observed 9 telecommunication satellites and 1 weather satellite of 6 countries. The obtained spectral data showed that satellites could be classified and grouped with similar basic spectral feature. We divided the 10 satellites into 4 groups based on spectral slop and reflectance. It is suggested that the material types of the satellites can be determined through spectral comparisons with the ground laboratory data. We will continuously observe additional geo-stationary satellites for the accurate classification of spectral features.

Lee, D. K.; Kim, S. J.; Han, W. Y.; Park, J. S.; Min, S. W.

2001-11-01

100

On the potentials of a system of transionospheric sounding by geostationary satellites  

Microsoft Academic Search

Transionospheric sounding is a novel technique of satellite\\/ground-based investigation for the entire ionosphere, using satellite ionosondes of the Intercosmos-19 satellite type. Attention is presently given to a system based on this technique that employs three geostationary satellites. The accurate determination of the sounding 'portion frequency' requires a ground ionosonde for automatic calculation of the satellite's maximum usable frequency, conducted by

M. K. Serafimova; K. B. Serafimov

1987-01-01

101

Categorizing precipitating clouds by using radar and geostationary satellite  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

102

Radiation Products based on a constellation of Geostationary Satellites  

NASA Astrophysics Data System (ADS)

The various components of the surface radiation budget present high variability in time and space, particularly over land surfaces where spatial heterogeneity of the upward fluxes is high. Geostationary satellites are well-suited to describe the daily cycle of downward and upward radiation fluxes and present spatial resolutions of the order of 3-to-5 km at sub-satellite point, acceptable for many applications. The work presented here is being carried out within the framework of Geoland-2 project, and aims the use of data from geostationary platforms to generate, archive and distribute in near real time four component of the surface radiation budget: land surface albedo, land surface temperature (LST) and downward short- and long-wave fluxes at the surface. All four components are retrieved from the following satellites - GOES-W covering North and South America, Meteosat Second Generation (MSG) covering essentially Europe and Africa, and MTSAT covering part of Asia and Australia. The variables are retrieved independently from each satellite and then merged into a single field, with a 5 km spatial resolution. Data are generated hourly in the case of the downward fluxes and LST, and 10-daily in the case of albedo. In regions covered by both GOES and MSG disks, the interpolated field makes use of both retrievals, giving more weight to those with lower uncertainty. The four components of the surface radiation budget described above are assessed through comparisons with similar parameters retrieved from other sensors (e.g., MODIS, CERES) or from models (e.g., ECMWF forecasts), as well as with in situ observations when available. The presentation will be focused on a brief description of algorithms and auxiliary data used in product estimation. The results of inter-comparisons with other data sources, along with the identification of the retrieval conditions that allow optimal / sub-optimal estimation of these surface radiation parameters will also be analysed. The radiation products generated within the Geoland-2 project are freely available to the user community.

Trigo, I. F.; Freitas, S. C.; Barroso, C.; Macedo, J.; Perdigão, R.; Silva, R.; Viterbo, P.

2012-04-01

103

Technologies of diffractive imaging system for high-resolution earth observation from geostationary orbit  

NASA Astrophysics Data System (ADS)

High-resolution earth observation from geostationary orbit (GEO) is a good way to satisfy the increased time resolution for resource, environment and disaster monitor. Earth observation from geostationary orbit will require optical remote sensor with ultra-large aperture. Given size, weight and launch ability constraints, as well as cost consideration, the traditional monolithic aperture optical system couldn't satisfy the need. This paper gives a new method, the diffractive imaging system. Diffract ive imaging system is a feasible way to realize high-resolution earth observation from geostationary orbit. The principle of diffract ive imaging system is introduced firstly, then, the primary design of remote sensor with 1m resolution from geostationary orbit using diffractive imaging system is analyzed. Finally, the key technologies are analyzed and feasible solutions are given.

Chen, Xiaoli; Su, Yun; Jiao, Jianchao

2013-08-01

104

Satellite-to-satellite tracking orbit determination  

Microsoft Academic Search

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

B. T. Fang

1978-01-01

105

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

NASA Astrophysics Data System (ADS)

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

Rajaram, G.; et al.

2006-11-01

106

Aerosol Spatial and Temporal Variations Over a Coastal Area: Implications for Geostationary Satellite Measurements  

NASA Astrophysics Data System (ADS)

Coastal area is of great interest to the community of air pollution and climate change studies. The dispersion of air pollutants is strongly influenced by complex coastal meteorology, such as land-sea breeze circulations interacting sometimes with mountain-valley circulations. On the other hand, radiatively active air pollutants, like aerosols, could influence the coastal meteorology and hence feed back on the atmospheric dispersion. Coastal area is also an interface for impacts of air pollution on coastal ocean ecosystems. In this study, we look into spatial and temporal variations of aerosol optical depth (AOD) over southern California by examining high-resolution Community Multiscale Air Quality (CMAQ) model simulations, and Aerosol Robotic Network (AERONET) measurements, and the Geostationary Operational Environmental Satellite (GOES) retrievals. Both model simulations and observations show that aerosol has large spatial and temporal variations. Autocorrelation analyses of AOD suggest that these variations can be adequately (r >0.9) captured by satellite observations with time resolution on an order of 1-2 hours and spatial resolution of 4-7 km. Both model and observations show substantial day-to-day variation of aerosols over the region, which is mainly determined by the evolution of land-sea breeze circulations interacting with mountain flows. Modeling the feedbacks of aerosols on coastal meteorology and air quality requires high-resolution measurements from a geostationary orbit as a constraint.

Yu, H.; Chin, M.; Tan, Q.; Hu, Y.; Kondragunta, S.; Ciren, P.; Holben, B. N.

2009-12-01

107

Geostationary Operational Environmental Satellite (Goes) Data Collection System. Task 2. Design of Remote and Master Terminals.  

National Technical Information Service (NTIS)

The geostationary operational environmental satellite (GOES) system is designed to provide emergency warning and environmental data collection and dissemination services. The objective of Task 2 is to prepare specifications for a set of three ground termi...

1967-01-01

108

Geostationary Operational Environmental Satellite (Goes) Data Collection System. Task I. Definition of Data Collection System.  

National Technical Information Service (NTIS)

The geostationary operational environmental satellite (GOES) system is designed to provide emergency warning and environmental data collection and dissemination services. Under the control of a control and data acquisition ground terminal, the GOES will r...

1967-01-01

109

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

110

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

111

Validating an operational physical method to compute surface radiation from geostationary satellites  

NASA Astrophysics Data System (ADS)

Models to compute global horizontal irradiance (GHI) and direct normal irradiance (DNI) have been in development over the last three decades. These models can be classified as empirical or physical based on the approach. Empirical models relate ground-based observations with satellite measurements and use these relations to compute surface radiation. Physical models consider the physics behind the radiation received at the satellite and create retrievals to estimate surface radiation. While empirical methods have been traditionally used for computing surface radiation for the solar energy industry, the advent of faster computing has made operational physical models viable. The Global Solar Insolation Project (GSIP) is a physical model that computes DNI and GHI using the visible and infrared channel measurements from a weather satellite. GSIP uses a two-stage scheme that first retrieves cloud properties and uses those properties in a radiative transfer model to calculate GHI and DNI. Developed for polar orbiting satellites, GSIP has been adapted to NOAA's Geostationary Operation Environmental Satellite series and can run operationally at high spatial resolutions. This method holds the possibility of creating high quality datasets of GHI and DNI for use by the solar energy industry. We present an outline of the methodology and results from running the model as well as a validation study using ground-based instruments.

Sengupta, Manajit; Heidinger, Andrew; Miller, Steven

2010-08-01

112

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

113

Implementation and Test of the Automatic Flight Dynamics Operations for Geostationary Satellite Mission  

NASA Astrophysics Data System (ADS)

This paper describes the Flight Dynamics Automation (FDA) system for COMS Flight Dynamics System (FDS) and its test result in terms of the performance of the automation jobs. FDA controls the flight dynamics functions such as orbit determination, orbit prediction, event prediction, and fuel accounting. The designed FDA is independent from the specific characteristics which are defined by spacecraft manufacturer or specific satellite missions. Therefore, FDA could easily links its autonomous job control functions to any satellite mission control system with some interface modification. By adding autonomous system along with flight dynamics system, it decreases the operator’s tedious and repeated jobs but increase the usability and reliability of the system. Therefore, FDA is used to improve the completeness of whole mission control system’s quality. The FDA is applied to the real flight dynamics system of a geostationary satellite, COMS and the experimental test is performed. The experimental result shows the stability and reliability of the mission control operations through the automatic job control.

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

2009-12-01

114

Communications and radio determination system using two geostationary satellites. Part I: System and experiments  

NASA Astrophysics Data System (ADS)

We developed two types of hybrid terminals that can provide both satellite communication and position determination services in one system. One terminal uses the single channel per carrier (SCPC) technique and the other uses the spread spectrum (SS) technique. To evaluate the performance of the two systems, we carried out experiments in Japan and in the Pacific Ocean using two geostationary satellites, ETS-V (150 deg E) and Inmarsat (180 deg E). The ranging accuracy between the mobile terminals and the base station via the satellites was found to be about 200 m using the SCPC system and about 10 m using the SS system. The measured positioning accuracy was about 1 km in the SCPC system and about 600 m in the SS system when experiments were carried out near Japan. The experimental results show that the positioning errors were mainly caused by the orbital determination errors of the two satellites. Presented here are the configurations and features of the SCPC and SS terminals, the experimental system, and the experimental results.

Morikawa, Eihisa; Miura, Ryu; Matsumoto, Yasushi; Kimura, Kazuhiro; Arakaki, Yoshiya; Ohmori, Shingo; Wakana, Hiromitsu

1995-04-01

115

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

116

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

117

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

118

Estimation of solar radiation at the sea surface with geostationary meteorological satellite data  

Microsoft Academic Search

Two methods to estimate solar radiation over oceans near Japan with Japanese Geostationary Meteorological Satellite (GMS) are presented. One is the estimate by means of cloud amount derived from cloud imagery by GMS. An empirical formula that connects the solar radiation at the sea surface with cloud amount estimated by the satellite is proposed. The other is the estimate based

Young Seup Kim; Ryuuji Kimura

1992-01-01

119

Field experiment on simple vehicle antenna system using geostationary test satellite  

Microsoft Academic Search

This paper presents a field experiment of simple developed antenna system for land vehicle use which was tested by use of the Japanese geostationary test satellite called the engineering test satellite-VIII (ETS-VIII). The antenna system was mounted in a vehicle is compact, light weight, and promising for low cost system. The antenna system was built by a planar array antenna

Basari; K. Saito; M. Takahashi; K. Ito

2009-01-01

120

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

National Technical Information Service (NTIS)

This paper summarizes the results of processing GPS data from the AMSAT Phase 3D (AP3) satellite for real-time navigation and post-processed orbit determination experiments. AP3 was launched into a geostationary transfer orbit (GTO) on November 16, 2000 f...

G. Davis R. Carpenter M. Moreau F. H. Bauer A. Long D. Kelbel T. Martin

2002-01-01

121

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

NASA Astrophysics Data System (ADS)

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

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

1982-08-01

122

Basic experiment on charging mitigation of solar array in geostationary orbit environment  

Microsoft Academic Search

Many of spacecraft anomalies are caused by discharge on solar array. We investigate two methods to mitigate discharge on the solar array of spacecraft in geostationary orbit (GEO). The first method is to have discharge at safer points before the discharge occurs on solar cells. The second method is not to make the potential of the spacecraft negative. The mitigation

Y. Sanmaru; T. Ose; T. Kawasaki; Y. Sikata; S. Hosoda; M. Iwata; K. Toyoda; Mengu Cho; T. Fujita

2006-01-01

123

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

Microsoft Academic Search

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

Merkourios Karaliopoulos; Rahim Tafazolli; Barry G. Evans

2004-01-01

124

A method for the mapping of the apparent ground brightness using visible images from geostationary satellites  

Microsoft Academic Search

This paper deals with a method for mapping the apparent ground brightness on a pixel basis. It makes use of geostationary satellite visible data and generalizes the earlier work of Cano (1982). The detection of clouds larger than one pixel is performed in a time series by comparing the cloud-induced sensor response to the signal which would occur if the

G. Moussu; L. Diabate; D. Obrecht; L. Wald

1989-01-01

125

NOWCASTING CONVECTIVE INITIATION AND THUNDERSTORM CHARACTERISTICS THROUGH THE USE OF REAL-TIME GEOSTATIONARY SATELLITE INFORMATION  

Microsoft Academic Search

This study identifies the precursor signals of convective initiation within visible (VIS) and infrared (IR) imagery from the Geostationary Operational Environmental Satellite (GOES) instrument. Convective initiation (CI) is defined for this study as the first detection of Weather Surveillance Radar-1988 Doppler (WSR-88D) reflectivities ? 30 dBZ produced by convective clouds. Results indicate that CI may be forecasted up to 45

J. M. Mecikalski

126

Orbit Determination from the Satellite.  

National Technical Information Service (NTIS)

The paper presents simple methods for determining moderately eccentric orbits from the satellite; linear combinations of time-of-flight measurements are used exclusively. The method is based on a third-order expansion of the satellite law of motion in ter...

A. Braga-Illa

1968-01-01

127

Potential for calibration of geostationary meteorological satellite imagers using the Moon  

Microsoft Academic Search

ABSTRACT Solar-band imagery from geostationary meteorological satellites has been utilized in a number,of important applications in Earth Science that require radiometric calibration. Because these satellite systems typically lack on-board calibrators, various techniques have been employed to establish “ground truth”, including observations of stable ground sites and oceans, and cross-calibrating with coincident observations made by instruments with on-board calibration systems. The

Thomas C. Stone; H Ugh H. Kief Fer; Ian F. Grant

128

Low Earth orbit communications satellite  

NASA Astrophysics Data System (ADS)

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

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

129

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

Microsoft Academic Search

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

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

2005-01-01

130

Feasibility study for Geo-Stationary satellite observation of tropospheric pollutants  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

131

Remote monitoring of PV performance using geostationary satellites  

Microsoft Academic Search

This paper investigates the capability of satellite remote sensing to monitor the performance of ground-based photovoltaic (PV) arrays. A comparison between the actual output of PV power plants and satellite-simulated output estimates at six climatically distinct locations is presented. The paper shows evidence that the satellite resource is an effective means of monitoring the performance of PV systems and of

Richard Perez; Marek Kmiecik; Christy Herig; David Renné

2001-01-01

132

Debris impact damage and fragmentation of antenna structure in geostationary orbit  

NASA Astrophysics Data System (ADS)

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

Yasaka, Tetsuo; Meguro, Akira; Watanabe, Mitsunobu

1996-05-01

133

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

NASA Astrophysics Data System (ADS)

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

Hanada, Toshiya; Uetsuhara, Masahiko; Nakaniwa, Yoshitaka

2012-07-01

134

Satellite Orbital Interpolation Comparison Methods  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

135

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

NASA Astrophysics Data System (ADS)

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

Uetsuhara, Masahiko; Hanada, Toshiya

2013-09-01

136

Orbital lifetime of tethered satellites  

Microsoft Academic Search

Two models of an uncontrolled tethered system comprised of a free tether, a satellite trailing a tether, or two end bodies tethered together are developed to study the orbital lifetime characteristics of such systems. The first, a lumped mass model, including an extensible, nonconductive tether connecting end bodies modeled as spheres, is used as a 'truth' model. The second, a

Ted W. Warnock; John E. Cochran Jr.

1992-01-01

137

Many uses of the geostationary operational environmental satellite-10 sounder and imager during a high inclination state  

NASA Astrophysics Data System (ADS)

Geostationary Operational Environmental Satellite (GOES)-10 was the National Oceanic and Atmospheric Administration's (NOAA) operational GOES-West satellite for approximately eight years until it was retired as an operational satellite due to an ever increasing inclination in its orbit. Since its retirement, GOES-10 has been used for a number of applications, such as, special 1-minute imagery over parts of North America during its move to 60° West longitude, routine imagery of the Southern Hemisphere, the first operational Sounder coverage over South America, initialization of regional numerical weather prediction models, and even temporary recalled as the operational GOES-East satellite during a major GOES-12 anomaly. Products from the GOES-10 Sounder and/or Imager include: imagery, cloud-top parameters, atmospheric stability indices, total precipitable water vapor, motion vector winds, volcanic ash detection, fire detection and characterization, and precipitation. As the mission of GOES-10 has continued beyond its retirement as an official operational US satellite, already lasting more than double its five-year life expectancy, many countries have been afforded the opportunity to benefit from on-going GOES-10 measurements. The purpose of this paper is to summarize the history of GOES-10, especially the unique situation of GOES-10 operating in support of central and South America after its operational use.

Schmit, Timothy J.; Rabin, Robert M.; Bachmeier, A. Scott; Li, Jun; Gunshor, Mathew M.; Steigerwaldt, Henry; Schreiner, Anthony J.; Aune, Robert M.; Wade, Gary S.

2009-02-01

138

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

139

Estimating convective momentum fluxes using geostationary satellite data  

Microsoft Academic Search

Research and case studies have shown that convection plays a large role toward the feedbacks of momentum to the large-scale environment. Convective momentum fluxes have been studied for many years using in situ and aircraft measurements, along with numerical simulations. However, little work has been conducted on developing a method to use satellite remote sensing as a tool to diagnose

Christopher P. Jewett; John R. Mecikalski

2010-01-01

140

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

141

The long-term interaction of the Italian satellites abandoned in GEO with the orbital debris environment  

Microsoft Academic Search

Four Italian satellites have been launched, so far, in geostationary orbit: SIRIO, Italsat 1, Italsat 2, and SICRAL. The latter is the only one still operational: in fact, Sirio was abandoned close to the geopotential equilibrium point at 75?E in 1985, Italsat 1 was re-orbited above the geosynchronous altitude at the beginning of 2001 and Italsat 2 was moved, in

Luciano Anselmo; Carmen Pardini

2005-01-01

142

Detection of a geostationary satellite with the Navy Prototype Optical Interferometer  

NASA Astrophysics Data System (ADS)

We have detected a satellite via optical interferometry for the first time, using a 16 m baseline of the Navy Prototype Optical Interferometer (NPOI) to observe the geostationary communications satellite DirecTV-9S during the "glint" seasons of February-March 2008 and 2009 when the sun-satellite-NPOI geometry was favorable for causing specular reflections from geostationary satellites. We used the US Naval Observatory Flagstaff Station 1 m telescope to generate accurate positions for steering the NPOI. Stars are the easiest targets for optical/infrared interferometers because of their high surface brightness. Low surface brightness targets are more difficult: if they are small enough not to be resolved out by typical baselines, they are likely to be too faint to produce detectable fringes in an atmospheric coherence time. The 16 m NPOI baseline, the shortest available at the time of our observations, resolves out structures larger than ~ 1.5 m at the geostationary distance, while a typical size for the solar panel arrays is 2 m x 30 m. Our detection indicates that a small fraction of the satellite glinted, not surprising given that the solar panels are not accurately flat. Our fringe data are consistent with a two-component image consisting of a 1 to 1.3 m higher surface brightness component and a significantly larger lower surface brightness component. The brightness of the glints (2.m 4 and ~ 1.m 5 for the two detections in March 2009) and the size scale suggest that the compact component has an albedo of 0.06 to 0.13, while the larger-scale component is much darker, if circular geometry is assumed.

Armstrong, J. T.; Hindsley, R. B.; Schmitt, H. R.; Vrba, F. J.; Benson, J. A.; Hutter, D. J.; Zavala, R. T.

2010-07-01

143

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

144

Geostationary Operational Environmental Satellite (Goes) Data Collection System. Task III. Design, Assembly, and Integration of Demonstration Ground Terminals. Task IV. Satellite Data Collection Test and Demonstration Program.  

National Technical Information Service (NTIS)

The Geostationary Operational Environmental Satellite (GOES) system is designed to provide environmental data collection and dissemination and emergency warning services. Under the control of a CDA (Control and Data Acquisition) ground terminal, the GOES ...

1968-01-01

145

Evaluation on penetration rate of cloud for incoming solar radiation using geostationary satellite data  

NASA Astrophysics Data System (ADS)

Solar surface insolation (SSI) represents how much solar radiance reaches the Earth's surface in a specified area and is an important parameter in various fields such as surface energy research, meteorology, and climate change. This study calculates insolation using Multi-functional Transport Satellite (MTSAT-1R) data with a simplified cloud factor over Northeast Asia. For SSI retrieval from the geostationary satellite data, the physical model of Kawamura is modified to improve insolation estimation by considering various atmospheric constituents, such as Rayleigh scattering, water vapor, ozone, aerosols, and clouds. For more accurate atmospheric parameterization, satellite-based atmospheric constituents are used instead of constant values when estimating insolation. Cloud effects are a key problem in insolation estimation because of their complicated optical characteristics and high temporal and spatial variation. The accuracy of insolation data from satellites depends on how well cloud attenuation as a function of geostationary channels and angle can be inferred. This study uses a simplified cloud factor that depends on the reflectance and solar zenith angle. Empirical criteria to select reference data for fitting to the ground station data are applied to suggest simplified cloud factor methods. Insolation estimated using the cloud factor is compared with results of the unmodified physical model and with observations by ground-based pyranometers located in the Korean peninsula. The modified model results show far better agreement with ground truth data compared to estimates using the conventional method under overcast conditions.

Yeom, Jong-Min; Han, Kyung-Soo; Kim, Jae-Jin

2012-05-01

146

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

Code of Federal Regulations, 2010 CFR

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

2009-10-01

147

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

148

Theoretical study of the effect of atmospheric refraction correction on orbit determination accuracy of Symphonie in geostationary orbit  

Microsoft Academic Search

An error analysis program was used to determine the effect of atmospheric refraction correction on the orbit determination accuracy of the Symphonie satellite. It is found that the refraction correction has a unique effect on the determination of satellite length, irrespective of tracking strategy. The effect on other orbital elements depends on tracking strategy.

A. Leibold

1976-01-01

149

Generation of global surface albedo data set from archived geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Monitoring and understanding climate changes of the Earth require the generation of long-term and consistent global data set from observation. In this context, geostationary satellite observations could play a significant role thanks to the long duration of the missions and the corresponding archives, often covering more than two decades. In particular, their frequent cycle of acquisition can be used to document the anisotropy of the surface and thereby surface albedo. Hence, EUMETSAT has developed the so-called Geostationary Surface Albedo (GSA) algorithm based on an algorithm proposed by Pinty et al. This algorithm is capable of processing observations of any geostationary satellites to derive the surface albedo, accounting for the effects of the surface anisotropy and the aerosols. This algorithm has been implemented in the Operational reprocessing facility of EUMETSAT in order to generate reliable albedo dataset starting from the 1982, through the analysis of data acquired by the six different Meteosat first generation platforms for the satellites located at the 0 degree longitude. Observations acquired by the EUMETSAT satellites located over the Indian Ocean since 1998 have also been processed. The GSA algorithm has also been implemented at the Japanese Meteorological Agency (JMA) for the processing of the GMS-5 archive. EUMETSAT has the responsibility to integrate all these level-2 products into a unique level-3 broadband surface albedo product. The evaluation of this global surface albedo product relies on the comparison of pairs of contemporaneous products generated from two adjacent satellites sharing a common observation area and with the equivalent MODIS product. This latter comparison has revealed that both products agree within 10% relative difference. This study is performed under the framework of the Co-Ordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) project, a WMO initiative to establish a network of facilities ensuring continuous and sustained provision of high-quality satellite products related to the Essential Climate Variables (ECV), on a global scale, responding to the requirements of the Global Climate Observing system (GCOS). It demonstrates the contribution of operational weather satellites into the generation of consistent time series of surface albedo.

Govaerts, Yves; Okuyama, Arata; Latanzio, Alessio

2010-05-01

150

Capacity occupation strategy for data messaging over non-geostationary mobile satellite communication systems  

Microsoft Academic Search

Considerable interest has been focused on the possibility of employing a large number of low earth orbit (LEO) satellites to provide an overall global coverage. Capacity estimation of different LEO satellite constellations is derived in terms of satellite altitude and traffic offered. A capacity occupation strategy is proposed for the transmission of both telephone and wireless data messaging over LEO

Nawal A. Elfishawy; Salah Khamis

2001-01-01

151

The orbits of the retrograde Jovian satellites  

Microsoft Academic Search

A 2-Myr integration has been conducted for the sun-perturbed orbits of Saturn's four retrograde satellites, confirming that the apsis of Pasiphae is locked to that of Jupiter; its orbit is chaotic, with a 5000-yr inverse Liapunov exponent. The locking of two of these four satellites into this secular resonance, in addition to constraining theories of these satellites' formation, further suggests

Prasenjit Saha; Scott Tremaine

1993-01-01

152

A mission to preserve the geostationary region  

Microsoft Academic Search

The RObotic Geostationary orbit Restorer, ROGER, is a programme aimed at reducing the risk to satellite operations posed by the existence of failed and spent satellites and other categories of space debris. To achieve this, the concept of mass removal by an intervention mission is considered for the GEO region. This paper describes the results of studies into the level

D. Smith; C. Martin; M. Kassebom; H. Petersen; A. Shaw; B. Skidmore; H. Stokes; A. Willig

2004-01-01

153

A Near-Real-Time Global Geostationary Satellite Cloud and Radiation Retreival System  

NASA Astrophysics Data System (ADS)

Weather prediction models need more quantitative weather information for forecasting and nowcasting. This paper describes a prototype system to provide 3-hourly cloud properties from full-disk geostationary satellites (GEOSat) around the globe. Data from GOES11/12, Meteosat.-9, FY2-C/D and MTSAT is analyzed using a common set of algorithms to derive products including cloud mask, cloud phase, cloud base and top height, optical depth, ice and liquid water path, particle sizes, shortwave albedo and longwave flux. Overlap cloud properties are derived from GOES-12 and Meteosat using the CO2 channel 13.3 um. Active and passive remote sensing data from the surface and other satellites are being used to validate the products. Interactive tools for accessing and viewing the data products are demonstrated. Examples of nowcasting application and assimilation of the cloud products in numerical model are presented and future plans and challenges discussed.

Palikonda, R.; Minnis, P.; Spangenberg, D. A.; Ayers, J. K.; Khaiyer, M. M.; Trepte, Q. Z.; Chang, F.; Heck, P. W.; Chee, T. L.; Nguyen, L.; Nordeen, M.

2009-12-01

154

Estimation of large scale daily evapotranspiration using geostationary meteorological satellite observations  

NASA Astrophysics Data System (ADS)

Accurate estimate of daily evapotranspiration over large areas is important both for understanding hydrological processes on the earth and for water resources management. Remote sensing observations of land surface have been used to estimate evapotranspiration (ET) over large areas, when point measurements cannot provide such information efficiently because of insufficient coverage density. Conventional methods to estimate regional daily ET are based on extrapolation of instantaneous ET estimates usually from polar-orbiting satellite observations at clear sky moments and assuming clear sky conditions prevailing throughout the day. However, such methods are unable to overcome uncertainties caused by eventual cloud interference along a day course. The new generations of geostationary meteorological satellites having frequent temporal sampling and relatively higher spatial resolution than older generations, carries the promise of solving the problem of time integration to estimate daily ET. Such observations at high temporal resolution are particularly helpful in capturing the diurnal variation of land surface temperature, the most critical land surface parameter in determining the energy partitioning between sensible heat flux and latent heat flux. However, cloud-free measurements during a day may be sparse and not simultaneous for different pixels. A time series analysis technique using Fourier transfer analysis as described in Harmonic Analyze of Time Series (HANTS) is therefore needed to fill the gaps in sparse satellite observations due to clouds contamination. In this research, instantaneous latent heat flux in turn the evapotranspiration is calculated from an energy balance based model SEBS (Surface Energy Balance System) firstly using a set of land surface parameters provided by LandSAF products retrieved from observations of SEVIRI (Spinning Enhanced Visible and Infrared Imager) onboard Meteosat Second Generation (MSG). Secondly, HANTS algorithm is used to reconstruct gap-filled time series of instantaneous ET along a day. In the end, daily evapotranspiration is calculated from the reconstructed gap-filled time series of instantaneous estimation of evapotranspiration. The algorithm validation was done using data from limited number of flux tower sites of CarboEurope project in Europe by comparing the energy balance flux components estimated by SEBS with tower flux measurements. Analyses of daily variation of estimated surface heat fluxes show that the proposed method is able to generate large scale net radiation, sensible, latent, and soil heat fluxes that follow closely daily variation of the courses of these flux components as observed by ground measurements. It was found that abnormal values in the estimated latent heat flux are observed near cloudy pixels. It indicates that pixels close to cloudy pixels may be affected by clouds but not masked in the MSG land surface temperature product. In general, reconstruction of evapotranspiration time-series using HANTS algorithm is demonstrated to be a promising technique to overcome the interference of clouds and preserve inherent trends of evapotranspiration process over a day when applied to a large-scale. HANTS reconstruction is capable to maintain daily variation of evapotranspiration on less cloudy days by keeping good correlation with the ground measurements. However, the technique has proven to be limited to areas with cloud cover less than 60% along a day course. Comparison of the daily total ET estimated from SEBS/MSG/HANTS technique with daily ET calculated using conventional method (using one-time measurements of a day and assuming clear sky throughout a day) has shown that the former is less affected by the intensity of cloud interference along the day.

Jia, L.; Daamen, M.

2009-04-01

155

THE ORBITS OF THE OUTER URANIAN SATELLITES  

SciTech Connect

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

Brozovic, M.; Jacobson, R. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)], E-mail: marina.brozovic@jpl.nasa.gov

2009-04-15

156

Orbital Stabilization of 12-Hour Satellites.  

National Technical Information Service (NTIS)

Artificial Earth satellites with periods of approximately 12 hours are subject to resonance effects similar to those suffered by synchronous satellites. Highly eccentric 12-hour orbits at an inclination of about 63.4 degrees are of special interest, since...

R. R. Allan

1969-01-01

157

Ranging of Medium and Low Orbit Satellites.  

National Technical Information Service (NTIS)

This article introduces principles and methods associated with various types of satellite ranging methods. Mutual comparisons are made between various types of methods. An exposition is made of current trends in medium and low orbit satellite ranging.

X. Daxing Z. Huazhen Z. Suzhen

1996-01-01

158

First Resolved Images of a Spacecraft in Geostationary Orbit with the Keck-II 10 m Telescope.  

National Technical Information Service (NTIS)

Resolved images of a geostationary satellite were obtained on October 30 2009, with the adaptive optics on the largest telescope on the planet, the 10 m Keck-II on the 14000 foot summit of Mauna Kea. As part of an engineering run at the Keck-II 10 m teles...

J. D. Drummond R. H. Rast

2010-01-01

159

Study of the optimization of satellite system design for transfer orbit  

NASA Astrophysics Data System (ADS)

Geostationary transfer orbit (GTO) characteristics of former geosynchronous satellites; satellite configurations as to GTO requirements; telemetry and telecommand, thermal, power, and attitude control subsystems as to stabilization modes and GTO constraints; and apogee injection strategies (single/multiple burn, steering law) were reviewed. The investigations were confined to 2 Ariane 4 payload classes (2500 kg in GTO, dual-launch and 4200 kg in GTO, single launch), three-axis or slow barbecue stabilization during transfer orbit, and use of a liquid apogee injection system with low thrust level (400 N). A recommendation for an overall system optimization is presented.

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

1983-04-01

160

Estimating Incident Solar Radiation at the Surface from Images of the Earth Transmitted by Geostationary Satellites: the Heliosat Project  

Microsoft Academic Search

The goals of the Heliosat Project of Ecole Nationale Supérieure des Mines de Paris are: (i) to design a system for the estimation of incident solar radiation at ground level from images of the Earth acquired by geostationary satellites, (ii) to produce detailed maps of the spatial distribution of the global radiation and (hi) to improve the system depending upon

L. Diabaté; H. Demarcq; N. Michaud-Regas; L. Wald

1987-01-01

161

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

162

Space systems considerations in the design of advanced geostationary operational environmental satellites  

NASA Astrophysics Data System (ADS)

Advances in space systems are providing challenging opportunities for the design of smaller, lighter, more efficient and cheaper satellite systems. A review of spacecraft power systems, structural materials, thermal design and cooling systems, electronic modules and advances in detector technology is provided. The science requirements for NOAA's advanced imager are presented. The NASA Jet Propulsion Laboratory design trade study for NOAA's 8-channel advanced imager shows that a 30 cm aperture mirror design can meet most of NOAA's requirements; though superior, the 45 cm mirror design option was abandoned due to instrument mass restrictions. The Aerospace Corporation was requested by NOAA to compare consolidated and distributed architectures. There appears to be no significant advantage for NOAA in pursuing distributed architecture for our future systems. A lighter overall mass is the key driver in reducing geostationary launch vehicle costs. Instrument design trade studies and spacecraft architectural studies are helping NOAA to plan for the future GOES systems.

Achutuni, R.; Menzel, P.

1999-01-01

163

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

NASA Astrophysics Data System (ADS)

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

Reuter, Maximilian

2013-04-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

165

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

NASA Astrophysics Data System (ADS)

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

Oyoshi, K.; Tamura, M.

2009-12-01

166

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

NASA Astrophysics Data System (ADS)

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

Lohmeyer, W. Q.; Cahoy, K.

2013-08-01

167

Investigating cirrus cloud behavior using A-Train and geostationary satellite data  

NASA Astrophysics Data System (ADS)

Knowledge of how the large-scale dynamics are coupled with microphysical properties is necessary for parameterizing cirrus in climate models. In this study, the synergy of the CloudSat and CALIPSO instruments is exploited for identifying cirrus. Mesoscale-size cirrus events are defined using a combined CloudSat-CALIPSO cloud mask and temperature data for one year in the Atlantic basin. In order to characterize the tendencies of cirrus, the instantaneous view of A-Train satellites is augmented with the temporal view from a geostationary satellite. Cirrus events are tracked using an algorithm, which follows patterns of 6.2?m brightness temperature in consecutive water vapor images. NCEP/NCAR reanalysis data is used to determine the environments in which the cirrus events exist. The cirrus events are sorted based on pressure- radar reflectivity patterns using a k-means cluster algorithm. The six clusters that are identified include Single-Layer Cirrus, Thick Cirrus and Low Cloud, High Cirrus, Deep Cirrus, Mixed Cloud and Thin Cirrus, and Low Cloud. A cluster algorithm is also applied to the large-scale dynamics to determine the basic synoptic states for cirrus. This analysis results in six dynamic clusters including Deep Wave Cirrus, Developing Tropical Cirrus, Subtropical Jet Cirrus, Zonal Jet/Stationary Front Cirrus, Dissipating Tropical Cirrus, and Ridge Crest Cirrus. We find that large-scale dynamic types do not necessarily predetermine the cirrus cloud properties.

Berry, Elizabeth

168

0.5-4 Å X-Ray Brightenings in the Magnetosphere Observed by the Geostationary Operational Environmental Satellites  

NASA Astrophysics Data System (ADS)

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 × 10–8 W m–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.

2013-10-01

169

Short Arc Orbit Determination for Anna Satellite.  

National Technical Information Service (NTIS)

A differential orbit correction procedure and its application to observations distributed over short arcs of the geodetic satellite ANNA are presented in this report. Also included is an analysis of the accuracy achieved in determining the position and ve...

J. P. Rossoni P. Sconzo D. Winfield

1964-01-01

170

LOS Alamos geostationary orbit synoptic data set: A compilation of energetic particle data  

NASA Astrophysics Data System (ADS)

Energetic electron (30 to 2000 keV) and proton (145 keV to 150 MeV) measurements made by Los Alamos National Laboratory sensors at geostationary orbit 6.6 R/sub E/ are summarized. The data are plotted in terms of daily average spectra, 3-h local time averages, and in a variety of statistical formats. The data summarize conditions from mid-1976 through 1978 (S/C 1976-059) and from early 1977 through 1978 (S/C 1977-007). The compilations correspond to measurements at 350W, 700W, and 1350W geographic longitude and, thus, are indicative of conditions at 90, 110, and 4.80 geomagnetic latitude, respectively. Most of this report is comprised of data plots that are organized according to Carrington solar rotations so that the data can be easily compared to solar rotation-dependent interplanetary data. As shown in prior studies, variations in solar wind conditions modulate particle intensity within the terrestrial magnetosphere. The effects of these variations are demonstrated and discussed. Potential uses of the Synoptic Data Set by the scientific and applications-oriented communities are also discussed.

Baker, D. N.; Higbie, P. R.; Belian, R. D.; Aiello, W. P.; Hones, E. W., Jr.

1981-08-01

171

Geos-C Orbit Determination with Satellite to Satellite Tracking.  

National Technical Information Service (NTIS)

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

P. Argentiero

1974-01-01

172

The Orbits of the Satellites of Pluto  

Microsoft Academic Search

We report on the latest ephemerides (plu020) for the satellites of Pluto. The model for the satellites' orbits is numerical integration. External perturbations due to the Sun (augmented with the inner solar system planets), Jupiter, Saturn, Uranus, and Neptune are included. The data set consists of astrometric measurements and lightcurves from the mutual events and occultations. Our goal was not

Marina Brozovic; R. A. Jacobson

2010-01-01

173

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

174

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

175

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

2013-03-01

176

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.

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

2013-01-01

177

Wedge-filter Imaging Sounder for Humidity (WISH): a practical NPOESS P3I and geostationary Earth orbit high-spatial resolution sensor  

NASA Astrophysics Data System (ADS)

Tropospheric wind estimation is among the top priorities for the NPOESS Pre-Planned Product Improvement (P3I). This Environmental Data Record (EDR) can be achieved by tracking high spatial resolution altitude-resolved water vapor features at appropriate timescales using humidity imaging sounder observations. A Wedge-filter Imaging Sounder (WIS) can provide the required humidity imagery and has already been studied for application in geostationary orbit. The geostationary WIS would use spatially variable wedge filter spectrometers to collect earth radiances with ~1 km resolution over a broad infrared (710-2900 cm-1) spectral region at 1% spectral resolution. The proposed sensor is a compact, lightweight, and rugged imaging sounder with better sensitivity, spectral resolution, spatial resolution than the current multispectral GOES imager and with full disk coverage rates. A Wedge-filter Imaging Sounder for Humidity (WISH) incorporates the same Raytheon WIS technology and is being proposed for consideration for flight on the NPOESS 2130 and 1730 LTAN spacecrafts. WISH would take advantage of the payload capacity available for P3I demonstrations in NPOESS and would serve as a risk reduction and technology demonstration for future NOAA environmental satellite missions. In this paper, we present our analysis of WISH performance toward achieving the NPOESS P3I tropospheric wind objective. The practicality of WISH for the current NPOESS LTAN spacecraft configuration and its instrument concept, sensor design, detector performance, measurement calibration, and system specification is discussed in a companion paper.

Huang, Hung-Lung A.; Bloom, Hal J.; Puschell, Jeffery J.; Menzel, Paul W.

2005-01-01

178

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

179

A mission to preserve the Geostationary Region (ROGER)  

Microsoft Academic Search

The high strategic and commercial value of the geostationary region is unquestioned. It is known that many satellites are not re-orbited at the end of their mission for a number of reasons. Previous studies have investigated the possibility of rendezvous and docking with an uncontrolled target and concluded a basic technical plausibility. Thus the possibility exists that spent satellites could

D. Smith; K. C. Martin; H. Petersen; A. Shaw; B. Skidmore; H. Stokes; A. Willig

2002-01-01

180

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

181

The Orbits of Neptune's Outer Satellites  

NASA Astrophysics Data System (ADS)

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.

Brozovi?, Marina; Jacobson, Robert A.; Sheppard, Scott S.

2011-04-01

182

Secular motion around synchronously orbiting planetary satellites.  

PubMed

We investigate the secular motion of a spacecraft around the natural satellite of a planet. The satellite rotates synchronously with its mean motion around the planet. Our model takes into account the gravitational potential of the satellite up to the second order, and the third-body perturbation in Hill's approximation. Close to the satellite, the ratio of rotation rate of the satellite to mean motion of the orbiter is small. When considering this ratio as a small parameter, the Coriolis effect is a first-order perturbation, while the third-body tidal attraction, the ellipticity effect, and the oblateness perturbation remain at higher orders. Then, we apply perturbation theory and find that a third-order approach is enough to show the influence of the satellite's ellipticity in the pericenter dynamics. Finally, we discuss the averaged system in the three-dimensional parametric space, and provide a global description of the flow. PMID:16396586

Lara, Martin; San-Juan, Juan F; Ferrer, Sebastián

2005-12-01

183

Parallel computation of satellite orbit acceleration  

NASA Astrophysics Data System (ADS)

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

Fukushima, Toshio

2012-12-01

184

A Concept for Satellite Orbit Sensitivity Analysis  

Microsoft Academic Search

\\u000a A satellite’s trajectory around a celestial body, e.g. the Earth, is mainly influenced by the gravitational field of the body.\\u000a This causes perturbations of the orbit which would be a Keple-rian ellipse in the ideal case. Measuring these perturbations\\u000a allows an analysis of the gravitational field itself. It is quite obvious that different trajectories are perturbed in different\\u000a ways depending

Erik W. Grafarend; Christof Schafer

185

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

NASA Astrophysics Data System (ADS)

The analysis of satellite solar power station (SSPS) is carried out for some specified locations (Delhi, Mumbai, Kolkata and Bengaluru) in India and consequently the performance of the system is evaluated for geostationary earth orbit (GEO) based SSPS, low earth orbit (LEO) based SSPS and Molniya (quasi geostationary) orbit based SSPS for sites located at different latitudes. The analysis of power; received energy over a year and weight of the rectenna array for the same beam intensity showed varied results for Molniya orbit based SSPS, LEO based SSPS and GEO based SSPS. The power delivered by the LEO SSPS was highest which indicated that this SSPS may be efficient for the short term power requirement. However, it is observed from the results of the energy received over a year that the GEO based system is suitable for base load power plant as it is capable of delivering constant energy through out a year. Further, the weight of the rectenna and hence the space required for ground station for same power output is smallest for Molniya orbit based system for a range of rectenna array radius considered. It is thus envisaged that the Molniya orbit based system would be a better choice for commercial use of SSPS. These findings may help for judicious selection of satellite orbit and ground station location for placing the satellite for SSPS for various applications.

Chaudhary, Kalpana; Vishvakarma, Babau R.

2010-11-01

186

Resolution enhancement for microwave-based atmospheric sounding from geostationary orbits  

Microsoft Academic Search

The purpose of this study is to develop and evaluate techniques that improve the spatial resolution of the channels already selected in the preliminary studies for Geostationary Observatory for Microwave Atmospheric Soundings (GOMAS). Reference high resolution multifrequency brightness temperatures scenarios have been derived by applying radiative transfer calculation to the spatially and microphysically detailed output of meteorological events simulated by

F. Di Paola; S. Dietrich

2008-01-01

187

Performance of a global circuit-switched satellite communication network  

Microsoft Academic Search

A circuit-switched network consisting of multiple low Earth orbiting satellites and three geostationary satellites is considered. Crosslinks among low-orbit satellites are used as the major communication channels, while calls are routed via geostationary satellites only when low-orbit routes exceed or equal to a hop-count threshold. Simulation results are used to illustrate the network throughput under various traffic conditions and different

Zsehong Tsai; Chuan-Chen Chuang; Jin-Fu Chang; Chun-Ming Huang

1994-01-01

188

A synthetic environment for satellite modeling and satellite orbital motion  

NASA Astrophysics Data System (ADS)

Analysts tasked to study satellites moving in space must often rely on photographs to conduct their analysis. Often these photographs do not adequately represent how satellites move in space, their spatial relationships, or their interaction with other satellites. What analysts need is a three-dimensional synthetic environment that depicts satellites as they actually move and interact in space. The early development of the Satellite Modeler (SM), a system that allows analysts to study satellite motion and maneuvering of computer aided design (CAD) models of those satellites in a three-dimensional orbit, is addressed. The system contains equipment that allows analysts to view the models either in a head mounted display, on a high resolution monitor, or on a computer workstation monitor. Analysts can also video tape a session in the synthetic environment. A voice recognition system allows the analyst to give voice commands to the synthetic environment that modify model movement or his view of the models. The modeler also allows the analyst to script the movements of models to duplicate the movements of actual satellites in space.

Pond, David L.

1992-12-01

189

COSPAS-SARSAT Satellite Orbit Predictor, Volume 7.  

National Technical Information Service (NTIS)

The satellite orbit predictor, 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 (LUT), is discussed. The predictor allows the user ...

M. L. Friedman

1986-01-01

190

Direct Dissemination of Data from ESA's (European Space Agency's) Future In-Orbit Infrastructure.  

National Technical Information Service (NTIS)

An overall information system which permits users on the Earth, equipped with relatively small satellite user terminals to obtain data or telescience services from low Earth orbit satellites by relay through geostationary DRS satellites, based upon their ...

S. Maudal B. Rognes E. Vefsnmo L. Rorhlt A. Sandvik

1988-01-01

191

Satellite orbits guidance using state space neural network  

Microsoft Academic Search

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

Mohamed A. Zayan

2006-01-01

192

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

193

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

194

MACC/MACC-II : the case for composition measurements from the geostationary orbit  

NASA Astrophysics Data System (ADS)

The MACC (Monitoring Atmospheric Composition and Climate, 2009-2011) and MACC-II (2011-2014) European projects are operating pre-operational services for atmospheric composition and solar/UV radiation in the context of the GMES (Global Monitoring for Environment and Security) program. The services are provided using advanced assimilation and forecast systems: one for the global scale, based upon the Integrated Forecast System (IFS) of ECMWF, and an ensemble of seven regional air quality models (CHIMERE, EMEP, EURAD, LOTOS-EUROS, MATCH, MOCAGE, SILAM) covering Europe. The products comprise analyses, forecasts, delayed mode analyses (taking into account validated data that are not available in Near-Real-Time) and multi-year re-analyses. The large amount of satellite and in-situ composition data currently used for assimilation and/or validation will be briefly presented: greenhouse gases, aerosol, reactive gases and surface air quality. A significant effort in MACC/MACC-II is devoted to models and products evaluation as well as to assimilation of data of various kinds. This effort is hampered by the current global observing system of atmospheric composition, as the overall dataset is mostly comprised of surface in-situ sites (WMO/GAW, air quality networks...) and of satellite products with limited vertical information and time coverage (LEO orbits) -with only few exceptions among which ozone sondes, lidars and MOZAIC-IAGOS aircraft data. The projects for GEO or quasi-GEO composition monitoring developing in Europe (Sentinel-4 and IRS on-board Meteosat Third Generation; the MAGEAQ mission concept), in North America (GEO-CAPE in the US PHEMOS in Canada) and in Asia (GEMS in Korea; projects in Japan and China) are thus regarded as a much needed additional observational component. Combining high spatial and temporal resolutions (as well as some vertical profiling capability in the case of multi-spectral instruments), such instruments would allow to evaluate and/or constrain models and, in fine, to provide better products. They would also allow to characterise better the variability of key pollutants (ozone, NO2, CO and to some extent aerosols) in the lower troposphere, which is also important in the perspective of understanding how changes induced by climate change could affect Air Quality. In turn, the models used in MACC/MACC-II can be used to set up OSSEs and help design the most adapted instruments: illustrations will be provided using one of the regional models, MOCAGE from Meteo-France.

Peuch, V.; Lahoz, W.; Orphal, J.; Attie, J. E.; El Amraoui, L.; MACC; MACC-II consortia

2011-12-01

195

Orbital evolution of the main Uranian satellites  

NASA Astrophysics Data System (ADS)

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

Verheylewegen, E.; Noyelles, B.

2011-10-01

196

A new higher performance NGO satellite for direct audio\\/video broadcast  

Microsoft Academic Search

A three satellite constellation using non-geostationary orbits (NGO) was launched in the latter half of 2000. It is providing direct satellite broadcasting audio and video services to over 9 million mobile and fixed subscribers throughout North America. The constellation will be augmented with a geostationary satellite called FM-5 in 2009, providing increased availability to the user with this “Hybrid” constellation.

Robert D. Briskman; Joseph V. Foust

2010-01-01

197

Design and implementation of the flight dynamics system for COMS satellite mission operations  

Microsoft Academic Search

The first Korean multi-mission geostationary Earth orbit satellite, Communications, Ocean, and Meteorological Satellite (COMS) was launched by an Ariane 5 launch vehicle in June 26, 2010. The COMS satellite has three payloads including Ka-band communications, Geostationary Ocean Color Imager, and Meteorological Imager. Although the COMS spacecraft bus is based on the Astrium Eurostar 3000 series, it has only one solar

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

2011-01-01

198

Parallel Orbit Propagation and the Analysis of Satellite Constellations.  

National Technical Information Service (NTIS)

This thesis describes the development of a scalable, portable parallel orbit propagator, with application to the analysis of satellite constellations, The Draper Semianalytic Satellite Theory (DSST) is coupled with the Parallel Virtual Machine (PVM) softw...

S. T. Wallace

1995-01-01

199

Sentinels in the Sky: Weather Satellites.  

ERIC Educational Resources Information Center

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

Haynes, Robert

200

Modular telecommunication satellite network using on-orbit telerobotic assembly  

Microsoft Academic Search

Orbital structures are currently limited by the payload capacity of launch vehicles. Satellite mass and volume constraints restrict the maximum size of solar arrays, antenna diameters, fuel tanks, and other satellite subsystems, thereby limiting overall satellite capability and effectiveness. In this study we address these issues by proposing the assembly of global telecommunications satellite network, the Ansible, that takes advantage

S. Ayer; G. Drayer; S. England; H. Laird; E. Romo; T. Schuman

2001-01-01

201

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

202

Resolution enhancement for microwave-based atmospheric sounding from geostationary orbits  

NASA Astrophysics Data System (ADS)

The purpose of this study is to develop and evaluate techniques that improve the spatial resolution of the channels already selected in the preliminary studies for Geostationary Observatory for Microwave Atmospheric Soundings (GOMAS). Reference high resolution multifrequency brightness temperatures scenarios have been derived by applying radiative transfer calculation to the spatially and microphysically detailed output of meteorological events simulated by the University of Wisconsin-Nonhydrostatic Model System. Three approaches, Wiener filter, Super-resolution and Image-fusion have been applied to some representative GOMAS frequency channels to enhance the resolution of antenna temperatures. The Wiener filter improved resolution of the largely oversampled images by a factor 1.5-2.0 without introducing any penalty in the radiometric accuracy. Super-resolution, suitable for not largely oversampled images, improved resolution by a factor ˜1.5 but introducing an increased radiometric noise by a factor 1.4-2.5. The Image-fusion allows finally to further increase the spatial frequency of the images obtained by the Wiener filter increasing the total resolution up to a factor 5.0 with an increased radiometric noise closely linked to the radiometric frequency and to the examined case study.

di Paola, F.; Dietrich, S.

2008-12-01

203

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

204

Satellite Power System (SPS) International Agreements.  

National Technical Information Service (NTIS)

This study identifies the problems in obtaining international agreements on geostationary orbit availability, microwave frequency allocations and microwave frequency standards for satellites transmitting solar power. Its findings and recommendations are b...

S. Grove

1978-01-01

205

NASA-Langley web-based operational real-time cloud retrieval products from geostationary satellites  

NASA Astrophysics Data System (ADS)

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, P.; Spangenberg, D. A.; Khaiyer, M. M.; Nordeen, M. L.; Ayers, J. K.; Nguyen, L.; Yi, Y.; Chan, P. K.; Trepte, Q. Z.; Chang, F.-L.; Smith, W. L., Jr.

2006-12-01

206

Cluster Analysis of Large Scale Dynamics of Growing and Dissipating Cirrus Events Observed by A-Train and Geostationary Satellite  

NASA Astrophysics Data System (ADS)

Knowledge of how large-scale dynamics are coupled with microphysical properties is useful for understanding cloud behavior and necessary for parameterizing cirrus in models. Atlantic cirrus events observed by CloudSat and the SEVIRI Imager on the Meteosat satellite are classified based on six large-scale dynamical parameters: 300mb relative humidity, 300mb omega, 300mb moisture flux convergence, 500mb omega, 500mb absolute vorticity advection, and 850mb temperature advection. A k-means clustering algorithm is used to identify different types of cirrus occurring in the tropics and mid-latitudes. Composite histograms of pressure and radar reflectivity are created for each cirrus cluster to examine differences in vertical structure. To characterize the tendencies of cirrus events within the dynamical regimes, observations from geostationary satellite data are used to track the cirrus events in time by following patterns of 6.2?m brightness temperature. Cirrus events are classified as growing if the average brightness temperature is decreasing in time. Using NCEP/NCAR reanalysis data, the composite dynamics of each cirrus cluster are investigated to determine how the large-scale meteorology plays a role in the evolution of the cirrus events. Differences in the vertical structure of the cirrus cloud microphysics are revealed with composite profiles of total water content from cloud base to cloud top.

Dupont, E. J.; Mace, G. G.; Minnis, P.; Palikonda, R.

2009-12-01

207

Satellite Meteorology: Online Remote Sensing Guide  

NSDL National Science Digital Library

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

208

Nonlinear Evolution of a Balloon Satellite Orbit  

NASA Astrophysics Data System (ADS)

The motion of a spherically symmetric balloon satellite near the equatorial plane is considered. Taking the Earth's oblateness and solar light pressure into account, the integral of motion can be obtained under certain simplifications. The eccentricity is related to the solar angle which represents an angle between pericenter and the Sun. This analytical approximation describes a large and complicated evolution of the eccentricity in corresponding areas of the phase space and the space of parameters. Phase portraits contain fixed saddle points and separatrices that divide different types of oscillations of the eccentricity. In the unsimplified problem, separatrices break down, and specific stochastic motions arise. The aims of the present study are (1) evaluation of the accuracy of analytical approximation with the help of numerical integration using a sufficiently complete model of motion and (2) numerical investigation of stochastic motions and dimensions of stochastic zones in the region of broken separatrices for an adequate model of motion. For a balloon satellite with a semimajor axis of 2.15 Earth's radii and a windage of 30 cm^2/g the dimensions of a stochastic zone in eccentricity and solar angle are 10^-5and 0.1°, respectively. The analytical approximation describes the orbit evolution in the right way, except for the cases of large eccentricities, e> 0.4, which corresponds to a pericenter height of less than 1400 km, where the atmospheric drag is already significant.

Kuznetsov, E. D.; Sokolov, L. L.

2001-11-01

209

Air Density in the Upper Atmosphere from Satellite Orbit Observations  

Microsoft Academic Search

FROM the rate of change of period of a satellite, it is possible to derive the density of the atmosphere at the altitude of the perigee of the orbit. Now that some ten successful satellite launchings have taken place, giving orbits with various perigee heights, the variation of air density with height can be derived over a considerable range of

G. V. Groves

1959-01-01

210

Effects of Solar Radiation Pressure on Earth Satellite Orbits.  

PubMed

Calculations show that, at a mean altitude of 1000 miles, radiation pressure can displace the orbit of the 100-foot Echo balloon at rates up to 3.7 miles per day, the orbit of the 12-foot Beacon satellite at 0.7 mile per day. For certain resonant conditions this effect accumulates, drastically affecting the satellite's lifetime. PMID:17833373

Parkinson, R W; Jones, H M; Shapiro, I I

1960-03-25

211

Orbits of the ten small satellites of Uranus  

SciTech Connect

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

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

1987-05-01

212

A standard library for modeling satellite orbits on a microcomputer  

NASA Astrophysics Data System (ADS)

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

Beutel, Kenneth L.

1988-03-01

213

The usefulness of auxiliary transfer orbit maneuvers for a near nominal geostationary mission  

Microsoft Academic Search

The usefullness of apogee and perigee raising maneuvers during transfer orbit operations in correcting errors due to launcher performance is illustrated. Maneuvers suggested are at perigee to raise the apogee and improve fuel usage, at apogee to raise the perigee in order to both improve fuel usage and decrease air drag, and between perigee and apogee to raise the perigee

F. Hechler; M. Rosengren; M. Soop

1981-01-01

214

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

NASA Astrophysics Data System (ADS)

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.

1992-07-01

215

NASA Now Minute: Orbital Mechanics: Earth Observing Satellites  

NASA Video Gallery

Dr. James Gleason, project scientist for NPP, explains what it takes for a satellite to stay in orbit, why there are different types of orbits, and why satellites orbit Earth at different altitudes depending on their purpose. NASA Now Minutes are excerpts from a weekly current events program available for classroom use at the NASA Explorer Schools Virtual Campus located at: › http://explorerschools.nasa.gov.

Heather Deiss

2011-11-01

216

Analysis of orbital geometry and orbit maintenance of an Earth observation satellite  

NASA Astrophysics Data System (ADS)

An introduction to a recurring sun-synchronous orbit is given so as to choose adequately an orbit for Earth monitoring satellites. An analysis of choice criteria is made taking into account the hardware of the satellite and the mission constraints. For the orbit maintenance, an introduction to the perturbation is given, concluding with a qualitative analysis of the orbit correction maneuvers and a quantitative analysis in terms of the fuel consumption.

Matosdemedeiros, Valder

1987-08-01

217

Discovery of 12 satellites of Saturn exhibiting orbital clustering.  

PubMed

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

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

2001-07-12

218

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

219

Modeling GPS satellite attitude variation for precise orbit determination  

Microsoft Academic Search

High precision geodetic applications 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

220

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

Microsoft Academic Search

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

E. I. Pritchard

1978-01-01

221

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

NASA Astrophysics Data System (ADS)

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

Brindley, Helen E.; Russell, Jacqueline E.

2009-12-01

222

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

NASA Astrophysics Data System (ADS)

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

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

1993-10-01

223

Validating an operational physical method to compute surface radiation from geostationary satellites  

Microsoft Academic Search

Models to compute global horizontal irradiance (GHI) and direct normal irradiance (DNI) have been in development over the last three decades. These models can be classified as empirical or physical based on the approach. Empirical models relate ground-based observations with satellite measurements and use these relations to compute surface radiation. Physical models consider the physics behind the radiation received at

Manajit Sengupta; Andrew Heidinger; Steven Miller

2010-01-01

224

Observation and Modeling of Geostationary Orbit Electron Energization Induced by Enhanced Dayside Whistler-Mode Waves  

NASA Astrophysics Data System (ADS)

We provide correlated observations of enhanced dayside whistler-mode waves and energetic electron acceleration collected by the CLUSTER and GOES satellites during the 23~24 September 2001 storm. Energetic (>0.6 MeV) electron fluxes are found to increase significantly during the recovery phase and the main phase, by a factor of ~50 higher than the prestorm level. These high electron fluxes occur when strong dayside whistler-mode waves are present. Two-dimensional (2D) numerical simulations are carried out and the results demonstrate that the dayside whistler-mode wave can contribute to such enhancements in electron flux within 24 h, consistent with the observation.

He, Yihua; Yang, Chang; He, Zhaoguo; Zhang, Zelong; Xiao, Fuliang

2013-09-01

225

Orbital evolution and origin of the Martian satellites  

NASA Astrophysics Data System (ADS)

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

Szeto, A. M. K.

1983-07-01

226

Revolutionary next generation satellite communications architectures and systems  

Microsoft Academic Search

This paper describes possible revolutionary next generation communications satellite missions and architectures. The satellite communications evolutionary background, current GSO's (geostationary orbit satellites), `Little', `Big' and `Broadband' NGSO's (non-GSO's), and enabling satellite technologies are briefly discussed. Converging technological and economic forces will drive us inevitably to the next decade's communication satellite systems and network architectures. The increasing pace of new capabilities,

J. R. Stuart; J. G. Stuart

1997-01-01

227

Parallel orbit propagation and the analysis of satellite constellations  

NASA Astrophysics Data System (ADS)

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

Wallace, Scott T.

1995-06-01

228

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

229

Flight Trials of a Geostationary Satellite Based Augmentation System at High Latitudes and for Dual Satellite Coverage  

Microsoft Academic Search

Several flight demonstrations have taken place over the past few years to show how the Wide-Area Augmentation System (WAAS), currently under development for the Federal Aviation Administration, will increase GPS accuracy, availability, and integrity for aviation. These demonstrations have been carried out with the support of the National Satellite Test Bed (NSTB). Using the real- time GPS data available from

Richard Fuller; Todd Walter; Sharon Houck; Per Enge

230

The stable orbit of the small satellite flying around the space station and the orbit maintenance  

Microsoft Academic Search

The stable orbit of a small satellite flying around the space station and the orbit maintenance are studied based on the Hill equation and a sliding-mode control (SMC) approach. First, the problem of the stable orbit of the small satellite flying around the space station is transformed into the sliding-mode control problem. Then, sliding-mode controllers are proposed to guarantee the

Jianbo Hu; Hongye Su; Weimin Wu; Jian Chu

2000-01-01

231

MLSR: a novel routing algorithm for multilayered satellite IP networks  

Microsoft Academic Search

Several IP-based routing algorithms have been developed for low-Earth orbit (LEO) satellite networks in recent years. The performance of the satellite IP networks can be improved drastically if multiple satellite constellations are used in the architecture. In this work, a multilayered satellite IP network is introduced that consists of LEO, medium-Earth orbit (MEO), and geostationary Earth orbit (GEO) satellites. A

Ian F. Akyildiz; Eylem Ekici; Michael D. Bender

2002-01-01

232

Satellite congestion  

NASA Astrophysics Data System (ADS)

At last count, there were more than 160 satellites in geostationary orbits, circling the earth at an altitude of 37,000 km, and according to a research review published recently by the Rand Corporation, that's already too crowded. The risk of physical collisions among satellites is small, say authors Alvin L. Hiebert and William Sollfrey, but there is an emerging problem with what they call “spectral and orbital congestion,” the result of too many satellites and ground stations sending out too many electromagnetic signals that can interfere with one another.The report comes at a time when the Federal Communications Commission is planning to reduce the spacing between satellites along the U.S. segment of the orbital arc so that 37 additional satellites can be squeezed into the high orbit favored for telecommunications. “As more satellites are launched and others are shifted to avoid collisions, interference problems will get more complicated,” say the authors of the report.

233

Why No Orbital Resonances among the Satellites of Uranus.  

National Technical Information Service (NTIS)

Most of the orbital resonances among the satellites of the major planets are thought to be assembled by differential tidal expansion of their orbits. Why this has not occurred for the Uranus system can be investigated by determining the resonances which w...

S. J. Peale

1987-01-01

234

Space Station's biggest challenge - Servicing satellites in orbit  

Microsoft Academic Search

Attention is given to NASA's use of the prospective Space Station for the servicing of satellites in orbit, beginning with simple refueling tasks and culminating with the repair of sophisticated components. The Space Station will eventually perform all types of servicing on a variety of free-flying, reusable, unmanned platforms, or 'free flyers', which after being carried into low earth orbit

J. H. Brahney

1985-01-01

235

Satellite laser ranging and orbit determination at Nottingham University  

Microsoft Academic Search

SODAPOP (Satellite Orbit Determination and Analysis Package Of Programs) is a computer software package which has been written and developed over seven years at Nottingham University. It is a complete SLR analysis suite, capable of precise orbit integration and the processing of both raw full-rate data and pre-processed normal points. It has been used to investigate a number of geophysical

V. Ashkenazi; C. J. Hill; T. Moore

1990-01-01

236

TAOS Orbit Determination Results lJsing Global Positioning Satellites  

Microsoft Academic Search

Orbit determination results for the Air Force Phillips Laboratory's Technology for Autonomous Operational Survivability (TAOS) satellite using a Rockwell AST V Global Positioning System (GPS) receiver are presented in this paper. Under a cooperative effort, GPS orbit determination technology developed at Jet Propulsion Laboratory (JPL) has been transferred to the U.S. Air Force. JPL's post processing differential GPS software MIRAGE

Joseph R; Bobby G. Williams; Peter J. Wolff

237

The Determination of the Orbits of the Outer Jovian Satellites  

Microsoft Academic Search

The eight outer satellites of Jupiter may be divided into two groups of four. Those in the first group, Himalia, Elara, Lysithea, and Leda, are in high inclination direct orbits between 11 and 12 million km from Jupiter. Those in the second group, Pasiphae, Sinope, Carme, and Ananke, are in high inclination retrograde orbits between 20 and 24 million km

R. A. Jacobson

2000-01-01

238

Orbit Improvement of the Satellites of the Outer Planets.  

National Technical Information Service (NTIS)

Data reduced from 127 plates showing Jupiter's and Saturn's satellites in the interval 1972 to 1974 are available on computer cards in the form of (O-C) residuals. Initial orbit calculations and several later orbit improvements for Jupiter XIII (Leda) cul...

K. Aksnes F. Franklin

1981-01-01

239

The electromagnetic compatibility design of the orbital test satellite  

Microsoft Academic Search

The design and specifications to ensure electromagnetic compatibility (EMC) on the Orbital Test Satellite are discussed. The satellite system is described and the overall EMC control philosophy outlined. The design of the power subsystem, the bonding requirements, and the harness design are given. The system was analyzed by mathematical modeling on a computer using SEMCAP (Specification and EMC Analysis Program).

R. Rosenberg

1978-01-01

240

Reduced domestic satellite orbital spacings at 4\\/6 GHz  

Microsoft Academic Search

The technical basis for satellite orbit spacing intersystem interference is examined. Several complex mathematical analyses of intersystem isolation and signal interactions are reported. As such, this report is addressed to the rather small community of communications engineers that concerns itself with intersystem interference. Compilations of equations, U.S. domestic satellite system characteristics, and signal parameters that are important in interference analysis

G. L. Sharp

1983-01-01

241

Secular love and tidal numbers of synchronously orbiting satellites  

Microsoft Academic Search

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

M. Bursa

1988-01-01

242

Retrieval of Aerosol Optical Thickness from Geostationary Satellite (GOES): assessment and improvement  

NASA Astrophysics Data System (ADS)

Taking advantage of high temporal resolution (every half hour) of GOES observations, NESDIS has developed an algorithm to retrieve aerosol optical depth (AOD) from measurements of a single visible channel. The ability of GOES AOD product to capture aerosol diurnal variability over large spatial scales has been successfully demonstrated during the INTEX-A and ICARTT/NEAQS field campaigns in providing guidance for aircraft and ship deployment. In addition, good agreement has been found between AODs from GOES , AERONET, and MODIS. However, current algorithm is based on a single fixed aerosol model, i.e., continental aerosol and a constant background aerosol (0.02). Those assumptions may not be valid for certain circumstances such as smoke and dust episodes. With the long term observations from both ground-based and satellite (MODIS and MISR) measurements and simulation results from global transport models available, better knowledge on the aerosol types and their temporal and spatial distribution can be developed. In this study, we first adopted dynamic aerosol model and their microphysical parameters from MISR Aerosol Climatology Product (ACP). Effect of this modification is assessed with comparisons to AERONET observations. Secondly, background aerosol climatology (i.e. minimum AOD) is constructed with long-term AERONET observations, to account for temporal (diurnal and monthly) and spatial variation of minimum AOD that is crucial for accurate surface reflectance retrieval. The results from this study are expected to reduce uncertainties and improve GOES AOD retrieval algorithm.

Ciren, P.; Kondragunta, S.; Laszlo, I.; Prados, A.

2006-05-01

243

Rotational speed study of tropical cyclone spiral rainband by using geostationary satellite images  

NASA Astrophysics Data System (ADS)

The studies of tropical cyclone spiral rainband activities usually used radar-based observation when not landing. The rotational velocities were calculated by manually or automatically matching the movement of storm-scale reflectivity from two sequences of radar data. In this study, we used satellite-based infrared data as the search objects. The rotational speed of outer rainband and different annular radii was obtained by using rotational maximum cross-correlation (MCC) technique as matching approach. The benefit of this approach is the ability to get large scale movements of tropical cyclones and get better understanding the nature of revolving. We apply typhoon Nangka(2003), Soudelor(2003), Morakot(2003) and Dujuan(2003) for studying rotational speed. The results show that the average speed of all is 4.6 degree per hour and median value is 4 degree per hour. When comparing with typhoon strength, it shows that the stronger typhoons have bigger rotational speed. When considering different annular radii, we get different rotational speed and found that more near typhoon center have bigger rotational speed.

Chao, C.; Liu, G.; Liu, C.; Huang, S.

2006-12-01

244

Physical and Orbital Properties of Some of Saturn's Small Satellites  

Microsoft Academic Search

We present Cassini imaging results on the orbits and physical properties for the small ring-region moons Pan, Atlas, and the Cassini-discovered Keeler gap moon, S\\/2005 S1 (1), as well as the newly discovered\\/recovered moons orbiting among the major satellites, Methone (S\\/2004 S1), Pallene (S\\/2004 S2), and the Dione co-orbital S\\/2004 S5 Polydeuces (2,3,4). We find that Atlas is undergoing a

C. C. Porco; P. Thomas; J. Spitale; R. A. Jacobson; T. Denk; S. Charnoz; D. C. Richardson; L. Dones; E. Baker; J. W. Weiss

2005-01-01

245

Earth System: Satellites  

NSDL National Science Digital Library

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

246

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

NASA Astrophysics Data System (ADS)

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

Paronis, Dimitris; Hatzopoulos, John; Dulac, Francois

2010-05-01

247

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-IDDI data 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.

2007-06-01

248

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

249

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

250

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

NASA Astrophysics Data System (ADS)

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

Gan, Qingbo; Ma, Jianbo; Xu, Jin

2010-05-01

251

Orbit determination of Tance-1 satellite using VLBI data  

NASA Astrophysics Data System (ADS)

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

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

2006-01-01

252

Precise orbit determination for the GOCE satellite using GPS  

NASA Astrophysics Data System (ADS)

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

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

253

Detection and orbit determination of tethered satellite systems  

NASA Astrophysics Data System (ADS)

A systematic algorithm for determining which satellites are tether-connected is described. It is assumed that observations in the forms of range, azimuth and elevation data, for several satellites, including singles, two-satellite tethered systems, and three-satellite tethered systems are available. The detection process is performed using the dynamic model and a minimum variance batch filter to process simulated observations over a period of ten minutes. In the process, the estimated acceleration per unit length between pairs of satellites due to a tether is assumed to be constant during this "short arc" observation period. The values of acceleration per unit length are used as indicators of which pairs of satellites are connected. Use of the algorithm is illustrated by applying it to a set of nine satellites that includes two tethered pairs. For small librational motion of the tethered pairs, values of the constraint accelerations per unit length that are large relative to zero were obtained. On the other hand, values very close to zero were obtained for un-tethered pairs. These results indicate that non-librating, two-satellite tethered systems can be successfully identified (i.e. "detected") when perfect and small-level noise corrupted observations are available. However, identification of two-satellite tethered systems with the large libration angle, or those with a very short tether when medium and large levels of noise are present is more difficult. The detection of a three-satellite tethered system was also performed with the same algorithm. After detection of a two-satellite tethered system (or three-satellite) is performed, its orbit may be determined by using long arcs of observations (over one orbital period). In the long arc estimation process used herein, the constraint acceleration per unit length is considered to be a time-varying variable. For an exemplary set of satellites, results for long arc estimations were obtained. Since observation data for both satellites in a tethered system were used and few approximations of the tether dynamics were made, the results are very accurate. The orbital motion of the three-satellite tether system was found to be similar to that of two-satellite tether system when the librational motion was small. The major difference was that larger tether accelerations were present due to another tether connected body. It should be relatively easy to incorporate the new method for detection and motion determination developed in this study into a general orbit determination process. (Abstract shortened by UMI.)

Choe, Nammi Jo

254

A census of orbital properties of the M31 satellites  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

255

G-MG Satellite  

NSDL National Science Digital Library

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

256

Minimum number of satellites for Earth coverage by a constellation of low-orbit satellites  

NASA Astrophysics Data System (ADS)

An analytical way for computing the minimum number of satellites in a low-orbit multi-satellite system with a 100 percent coverage requirement is described. A Walker delta pattern constellation is assumed for a certain class of earth coverage definition. To provide coverage of a particular ground station, the satellite orbital plane inclination must be equal to or greater than the latitude of the ground station. The analysis yields the number of satellites in each orbital plane and the number of such groups necessary, in terms of the height of the orbits. An efficient numerical simulation was prepared in order to check the analytical results; the agreement between the analytical results and the simulation was perfect.

Sidi, Marcel; Yaniv, Yoram

1992-02-01

257

LARES successfully launched in orbit: Satellite and mission description  

NASA Astrophysics Data System (ADS)

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

Paolozzi, Antonio; Ciufolini, Ignazio

2013-10-01

258

Japanese first optical interorbit communications engineering satellite (OICETS)  

NASA Astrophysics Data System (ADS)

The National Space Development Agency of Japan (NASDA) plans to conduct an optical inter-orbit ling experiment in cooperation with the European Space Agency (ESA). ESA will launch the ARTEMIS geostationary satellite equipped with the SILEX optical terminal. NASDA will launch the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) equipped with the LUCE optical inter-orbit communications equipment into low earth orbit. The link experiment will be conducted between these satellites with associated ground equipment in Europe and Japan.

Yamamoto, Akio; Hori, Toshihiro; Shimizu, Takafumi; Nakagawa, Keizo

1994-09-01

259

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

Microsoft Academic Search

The LARETS satellite was launched on September 26, 2004, into a circular orbit at an altitude of 690 km and with an inclination of 98.2°. This mission is a successor to the WESTPAC satellite which was launched to an altitude of 835 km six years before. The study is based on the observations taken by the global network of laser

Milena Rutkowska

2005-01-01

260

Secular effects in the orbits of the Galilean satellites  

NASA Astrophysics Data System (ADS)

This paper presents the results of an investigation into the secular behavior of the orbits of the Galilean satellites of Jupiter. Kamel's perturbation method is used to remove all the explicitly periodic variables from the differential equations that describe the long period behavior of the orbits to third order in the masses, and the resulting differential equations for the secular behavior are then solved. Several numerical examples are given to illustrate the sensitivity of the solution to variations in the masses of the satellites.

Brown, B. C.

1981-03-01

261

Calculation of satellite orbits for purposes of geodynamical research  

NASA Astrophysics Data System (ADS)

It is shown that the calculation of satellite orbits for the determination of geodynamical parameters can be carried out efficiently through the use of current numerical-integration algorithms combined with regularized equations of satellite motion (KS theory). It is demonstrated that Lageos observations can be analyzed using the direct integration of equations in rectangular coordinates by the Adams algorithm of variable order (based on divided differences, for example).

Taradii, V. K.; Tsesis, M. L.

1985-02-01

262

A feasibility study of a mobile communication network using a constellation of low earth orbit satellites  

NASA Astrophysics Data System (ADS)

An effort was made to study whether the increased survivability, true global coverage, and reduced path loss of a LEO network could be utilized to give a viable mobile communication system. The architecture of such a network is complex, but it is expected that the use of advanced technology can overcome most limitations. An optimum constellation is considered, and the first three layers of a digital network are examined. Under certain simplifying assumptions it is shown that the proposed configuration is viable and compares favorably with a similar geostationary network with regards to the overall space-segment cost. The cost benefit begins to favor the LEONET for simpler spacecraft. It is also noted that it may be possible to scale down the LEO constellation to a smaller size so as to provide continuous coverage above about 70 deg latitude, where geostationary satellites are ineffective. This hybrid architecture is also likely to minimize interference with geostationary satellite systems in the congested mobile bands.

Richharia, M.; Hansel, P. H.; Bousquet, P. W.; O'Donnell, M.

263

Positioning of Eutelsat II satellite from supersynchronous transfer orbit to reduce satellite velocity correction requirements  

Microsoft Academic Search

A maneuver is detailed for positioning the Eutelsat II satellite into a supersynchronous transfer orbit (STO) with attention given to the corresponding needs for satellite-velocity correction. Scheduling and sizing considerations are examined for velocity corrections emphasizing dual-site maneuver visibility. The proposed maneuvers are optimized in the analysis to provide both nominal and backup apogees for nominal and nonnominal maneuver execution.

Alois F. Leibold

1992-01-01

264

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

Microsoft Academic Search

Thermal infrared (TIR) remote sensing of land-surface temperature (LST) provides valuable information about the sub-surface moisture status required for estimating evapotranspiration (ET) and detecting the onset and severity of drought. While empirical indices measuring anomalies in LST and vegetation amount (e.g., as quantified by the Normalized Difference Vegetation Index; NDVI) have demonstrated utility in monitoring ET and drought conditions over

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

2011-01-01

265

OTS 2: Five years of thermal testing on a satellite in a geostationary orbit  

Microsoft Academic Search

In flight degradation rates of OTS-2 optical solar of reflectors (OSR), multilayer insulation (MLI) and paint thermo-optical material properties were determined. Equinox data show a significant increase in temperature with time. This increase is nearing stabilization, and is related to degradation of the coatings on the surfaces rotating daily with respect to the Sun vector (white paint on antenna dishes,

D. R. Chalmers; H. G. Konzok; J. P. Bouchez; D. Howle

1983-01-01

266

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

267

Development of a Flexible Solar Reflector for Geostationary Spacecraft  

NASA Astrophysics Data System (ADS)

In order to avoid electrostatic discharge on satellites caused by the accumulation of electric charges on their external surface, thermal control coatings should have a surface resistivity between 106 ?/square and 1010 ?/square or a bulk conductivity higher than 10-8 S.cm-1. The polysiloxane resin of a cold thermal control coating, the flexible solar reflector (FSR), was filled with different conducting nanoparticles: indium tin oxide, zinc oxide and multi-walled carbon nanotubes (CNTs). Adding conducting nanoparticles increased the electrical conductivity of the FSR but also degraded its thermooptical properties. A simulation test of electron bombardment in geostationary orbit was performed on some samples. The existence of electron bombardment induced conductivity allowed oxide-filled composites to evacuate electric charges more effectively than the CNT-filled composites. None of the composites exhibited the required properties for a new version of FSR for geostationary orbit. Although charge dissipation was achieved with two samples, their thermooptical properties were not acceptable.

Beigbeder, J.; Demont, P.; Remaury, S.; Nabarra, P.; Lacabanne, C.

2009-01-01

268

Tactical satellite orbital simulation and requirements study  

NASA Astrophysics Data System (ADS)

This note documents the results of a preliminary analysis of space communications requirements that employs scenarios for military operations in three widely separated geographical areas in which U.S. contingency operations could occur. The objectives of this research are to: (1) Assess communications requirements that were not met by military resources for Desert Shield/Desert Storm and other recent operations and might not be met without additional military resources in potential future contingencies, including a hypothetical contingency in the Southern Hemisphere; and (2) Determine how military satellites could be used to overcome shortfalls between requirements and existing or planned military communication systems.

Bedrosian, E.; Cesar, E.; Clark, J.; Huth, G.; Poehlmann, K.

269

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

270

Autonomous robotic operations for on-orbit satellite servicing  

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

271

Improving satellite vulnerability assessment to untrackable orbital debris  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

272

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

273

Satellite orbit perturbations in a dusty Martian atmosphere  

NASA Astrophysics Data System (ADS)

In this paper we calculate the effect of atmospheric dust on the orbital elements of a satellite. Dust storms that originate in the Martian surface may evolve into global storms in the atmosphere that can last for months can affect low orbiter and lander missions. We model the dust as a velocity-square depended drag force acting on a satellite and we derive an appropriate disturbing function that accounts for the effect of dust on the orbit, using a Lagrangean formulation. A first-order perturbation solution of Lagrange's planetary equations of motion indicates that for a local dust storm cloud that has a possible density of 8.323×10 -10 kg m -3 at an altitude of 100 km affects the orbital semimajor axis of a 1000 kg satellite up -0.142 m day -1. Regional dust storms of the same density may affect the semimajor axis up to of -0.418 m day -1. Other orbital elements are also affected but to a lesser extent.

Haranas, Ioannis; Pagiatakis, Spiros

2012-03-01

274

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

275

A Study on the Strategies of the Positioning of a Satellite on Observed Images by the Astronomical Telescope and the Observation and Initial Orbit Determination of Unidentified Space Objects  

NASA Astrophysics Data System (ADS)

An optical tracking system has advantages for observing geostationary earth orbit (GEO) satellites relatively over other types of observation system. Regular surveying for unidentified space objects with the optical tracking system can be an early warning tool for the safety of five Korean active GEO satellites. Two strategies of positioning on the observed image of Communication, Ocean and Meteorological Satellite 1 are tested and compared. Photometric method has a half root mean square error against streak method. Also null eccentricity method for initial orbit determination (IOD) is tested with simulation data and real observation data. Under 10 minutes observation time interval, null eccentricity method shows relatively better IOD results than the other time interval. For follow-up observation of unidentified space objects, at least two consecutive observations are needed in 5 minutes to determine orbit for geosynchronous orbit space objects.

Choi, Jin; Jo, Jung Hyun; Choi, Young-Jun; Cho, Gi-In; Kim, Jae-Hyuk; Bae, Young-Ho; Yim, Hong-Suh; Moon, Hong-Kyu; Park, Jang-Hyun

2011-12-01

276

Orbit utilization - Current regulations  

NASA Astrophysics Data System (ADS)

It is pointed out that an increasingly efficient use of the geostationary satellite orbit and spectrum is necessary to accommodate the growing number of planned U.S. domestic satellites, as well as those of other countries. Technical efficiency can be maximized by designing satellites in a homogeneous manner which minimizes transmission differences between satellites. However, flexibility is also needed to design domestic satellite facilities to respond to the diverse demands in a competitive market. The Federal Communication Commission (FCC) seeks to achieve a balance between these goals in their domestic satellite policies and regulations. In December 1980, the FCC authorized the construction of some 22 new domestic satellites and the launch of 18 satellites. Attention is given to orbit use policies and reduced orbital spacings.

Lepkowski, R. J.

277

GLOBAL MOBILE SATELLITE COMMUNICATIONS: A REVIEW OF THREE CONTENDERS  

Microsoft Academic Search

The era of satellite-based mobile communications systems started with the first MARISAT satellite which was launched into a geostationary orbit over the Pacific Ocean in 1976 to provide communications between ships and shore stations. The combination of high cost and unacceptably large equipment has kept mobile satellite communications (MSC) systems from appealing to the wider market of personal mobile communications.

Gary M. Comparetto

1994-01-01

278

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

279

Thermal design of large satellite transmitter antennas, exemplified for the HLS antenna  

Microsoft Academic Search

The effect of variation of parameters upon the thermal behavior of a satellite transmitting antenna is described. The investigations concern an elliptically edged reflector of 2.6 x 1.5 m for the HLS satellite. In view of the geostationary orbit of the satellite several conditions of solar radiation are considered: vertical and lateral insolation, satellite's and earth's shadow. Various thermal coatings,

R. Marten

1975-01-01

280

Thermal design of large satellite transmitting antennas, illustrated using the HLS antenna  

Microsoft Academic Search

The thermal behavior of a satellite transmitting antenna is described. The investigations concern an elliptically borded reflector of 2.6 X 1.5 sq m. Because of the geostationary orbit of the satellite, several conditions of solar radiation are considered; vertical and lateral insolation, satellite's and earth's shadow. Different thermal coatings, superinsulation, radomes, and radiator reflection of the satellite, were investigated. A

R. Marten

1975-01-01

281

The Determination of the Orbits of the Outer Jovian Satellites  

NASA Astrophysics Data System (ADS)

The eight outer satellites of Jupiter may be divided into two groups of four. Those in the first group, Himalia, Elara, Lysithea, and Leda, are in high inclination direct orbits between 11 and 12 million km from Jupiter. Those in the second group, Pasiphae, Sinope, Carme, and Ananke, are in high inclination retrograde orbits between 20 and 24 million km from Jupiter. Rocher and Chapront (1996 A&A 311, 710) have published orbits for Himalia, Elara, Pasiphae, and Sinope fit to observations from their discoveries through 1993. Apparently, only Herget (1968 AJ, 73, 737) has published orbits for Lysithea, Carme, and Ananke. These were later extended by Aksnes (1973 AJ, 78, 121) who also determined an orbit for Leda (1978 AJ, 83, 1249). To support the Galileo Project, I fit numerical integrations of all eight satellites to observations from their discoveries through 1994. I have extended the fit to include observations through January 2000. Among the additional observations are highly accurate CCD measurements obtained at both the US Naval Observatory, Flagstaff Station (Stone & Harris, to appear in AJ), and JPL's Table Mountain Observatory (Owen, private communication). The table below gives the number of observations of each satellite and the root-mean-square (rms) of the post-fit residuals. Observation Residual Statistics - rms Timespan Satellite ? ? \\cos? No. ? ? 1894-2000 Himalia 736 1\\farcs18 737 0\\farcs92 1905-2000 Elara 345 0\\farcs95 345 0\\farcs82 1908-2000 Pasiphae 472 1\\farcs13 472 0\\farcs89 1914-1998 Sinope 210 1\\farcs19 210 0\\farcs98 1938-1998 Lysithea 124 0\\farcs75 124 0\\farcs72 1938-1998 Carme 145 1\\farcs01 145 0\\farcs81 1951-1998 Ananke 134 0\\farcs88 134 0\\farcs88 1974-1998 Leda 67 0\\farcs87 67 0\\farcs70 The current integration includes perturbations due to the Sun, Saturn, the Galilean satellites, and the oblateness (J2 only) of Jupiter. The masses of Jupiter and the perturbing satellites and the Jupiter J2 are from the Galileo data analysis. Ephemerides for the satellites are available electronically from the JPL Horizons on-line solar system data and ephemeris computation service.

Jacobson, R. A.

2000-05-01

282

Control of satellite clusters in elliptic orbit with limited communication.  

PubMed

The cooperative control of satellite clusters in elliptical, low-Earth orbit is studied, with the goal of minimizing the necessary information passed among the individual satellites in the cluster. We investigate two possible control paradigms in this paper. The system is described using linearized equations of motion, allowing it to be expressed as a time-varying linear system. The control objective is to attain a required formation at a specified point along the orbit. A decentralized controller is used, in which each satellite maintains a local estimate of the overall state of the cluster. These estimates, along with any control information, are shared after any satellite executes a control action. The second paradigm is an extension of the first, in which state estimates are never shared, and only the control information is passed. In each case, less information being passed results in a higher computational burden on each satellite. Simulation results show cyclic errors, likely induced by higher-order terms in eccentricity and inclinations. The controller that shares state estimates performs much better than the controller that passes only control information. PMID:15220147

Chichka, David F; Belanger, Gene; Speyer, Jason L

2004-05-01

283

The flexural behavior of PACSAT (passive communication satellite) in orbit  

NASA Astrophysics Data System (ADS)

This report presents an analysis of the libration and vibration of a passive communications satellite known as PACSAT. It addresses the effects of various disturbing mechanical forces on verticality and straightness. Phenomena considered include orbital ellipticity, earth oblateness, solar and lunar gravity, radiation pressure, micrometeorial impacts, and thermal bending effects. The last two are the most important. It is concluded that the flexural misbehavior of PACSAT in orbit is such that it is most improbable that the present design (unsupported linear array) can perform its communications functions.

Sollfrey, W.

1983-02-01

284

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

285

NEUTRON ALBEDO MEASUREMENTS ON POLAR-ORBITING SATELLITES (thesis)  

Microsoft Academic Search

An experiment to measure the earth's neutron albedo was flown on three polar orbiting Agena satellites in 1962. The detector, a BFa counter within a moderator, was sur- rounded by a ring of charged-particle proportional counters to discriminate against neutrons produced by protons in the detector assembly. The results show an albedo flux of 0.085 _ 0.03 n\\/cm ' sec

J. H. Trainor; J. A. Lockwood

1964-01-01

286

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

287

47 CFR 25.135 - Licensing provisions for earth station networks in the non-voice, non-geostationary mobile...  

Code of Federal Regulations, 2011 CFR

...non-voice, non-geostationary mobile-satellite service. 25.135 Section 25.135...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...non-voice, non-geostationary mobile-satellite service. (a) Each applicant...

2011-10-01

288

47 CFR 25.135 - Licensing provisions for earth station networks in the non-voice, non-geostationary mobile...  

Code of Federal Regulations, 2012 CFR

...non-voice, non-geostationary mobile-satellite service. 25.135 Section 25.135...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...non-voice, non-geostationary mobile-satellite service. (a) Each applicant...

2012-10-01

289

Multicarrier SPINE tests on the orbital test satellite module A  

NASA Astrophysics Data System (ADS)

Two data experiments were originally conceived in 1975 by the European Space Agency (ESA) to act as a demonstration of potential business systems which could be operated through the future European Communication Satellite (ECS). These systems include the Satellite Transmission Equipment Linking Laboratories (STELLA) and the Space Informatics Network Experiment (SPINE). It was proposed by ESA to conduct a multicarrier test in module A of the Orbital Test Satellite (OTS) with the objective to try to establish modest estimates of the number of simultaneous SPINE transmissions which could be achieved given the constraint of bit error rates better than 0.00001. The test clearly demonstrated the viability of multicarrier operation of the SPINE experiment using module A.

Daly, P.

1982-12-01

290

Laser Application in the Control of Satellite Orbit  

NASA Astrophysics Data System (ADS)

The work deals with the laser application for extending the life-time of small-scale satellites launched with lasers into a low-altitude earth orbit. The required laser powers and the substance for laser ablation are discussed. It is demonstrated that for lack of needed laser ablation substance on the satellite higher requirements are imposed on the velocity of laser ablation products exhaust . As a result, the laser power consumption prove to be higher than in optimal (on laser energy expenses) conditions of acceleration of a moving body. At the same time the high laser energy consumption can be quite justified by extension of the operation time of high-cost equipment on the satellite.

Nastoyashchii, Anatoliy F.

2004-03-01

291

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

292

An introduction to satellite communications  

NASA Astrophysics Data System (ADS)

An expository treatment of the principles and practice of satellite communications is presented. The development of communications satellite services is described, and the evolution of satellites and earth stations to meet changing requirements is reviewed. The physics and geometry of the geostationary orbit and the construction and operation of satellites and launch vehicles are addressed. The essential factors governing the quality of speech, data, and television signals received via satellite are analyzed. Special attention is given to growth areas in satellite communications (including analog television transmission); digital methods of transmission of voice and data; the use of satellites for maritime, aeronautical, and land-mobile communications; and very-small-aperture terminals.

Dalgleish, Don I.

293

Contrast in low-cost operational concepts for orbiting satellites  

NASA Astrophysics Data System (ADS)

Older spacecraft missions, especially those in low Earth orbit with telemetry intensive requirements, required round-the-clock control center staffing. The state of technology relied on control center personnel to continually examine data, make decisions, resolve anomalies, and file reports. Hubble Space Telescope (HST) is a prime example of this description. Technological advancements in hardware and software over the last decade have yielded increases in productivity and operational efficiency, which result in lower cost. The re-engineering effort of HST, which has recently concluded, utilized emerging technology to reduce cost and increase productivity. New missions, of which NASA's Transition Region and Coronal Explorer Satellite (TRACE) is an example, have benefited from recent technological advancements and are more cost-effective than when HST was first launched. During its launch (1998) and early orbit phase, the TRACE Flight Operations Team (FOT) employed continually staffed operations. Yet once the mission entered its nominal phase, the FOT reduced their staffing to standard weekday business hours. Operations were still conducted at night and during the weekends, but these operations occurred autonomously without compromising their high standards for data collections. For the HST, which launched in 1990, reduced cost operations will employ a different operational concept, when the spacecraft enters its low-cost phase after its final servicing mission in 2004. Primarily due to the spacecraft"s design, the HST Project has determined that single-shift operations will introduce unacceptable risks for the amount of dollars saved. More importantly, significant cost-savings can still be achieved by changing the operational concept for the FOT, while still maintaining round-the-clock staffing. It"s important to note that the low-cost solutions obtained for one satellite may not be applicable for other satellites. This paper will contrast the differences between low-cost operational concepts for a satellite launched in 1998 versus a satellite launched in 1990.

Walyus, Keith D.; Reis, James; Bradley, Arthur J.

2002-12-01

294

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

NASA Astrophysics Data System (ADS)

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

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

295

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

296

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

297

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

298

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) is based on dual-frequency tracking data from onboard GPS receivers. The two frequencies allow it to eliminate the first order ionosphere effects on the level of the carrier phase measurement noise. Data screening and precise orbit determination (POD) procedures are optimized under the assumption of the availability of two frequencies. If only single-frequency data are 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 are considered. The potential of single-frequency POD in different environments is assessed by comparing the results with dual-frequency POD for LEOs orbiting at different orbital heights. Moreover, the impact of different data sampling rates on single-frequency POD is considered. Our study helps to define requirements for GPS receivers and POD algorithms for future LEO missions for which only moderate orbit accuracy is needed.

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

299

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

300

A mission to preserve the Geostationary Region (ROGER)  

NASA Astrophysics Data System (ADS)

The high strategic and commercial value of the geostationary region is unquestioned. It is known that many satellites are not re-orbited at the end of their mission for a number of reasons. Previous studies have investigated the possibility of rendezvous and docking with an uncontrolled target and concluded a basic technical plausibility. Thus the possibility exists that spent satellites could be removed from the operational region by one or more shuttle vehicles. This is the basis for the European Space Agency (ESA/ESTEC) study entitled Robotic Geostationary Orbit Restorer (ROGER). In full, the ROGER study will address the collision risk in GEO, identify workable economic and technical mission scenarios and propose a solution. To enable an accurate quantification of the risk in the operational GEO region a detailed assessment of the current and future status has been performed. This paper will present the results of this analysis, which includes a breakdown of the current utilisation of the GEO ring and an assessment of the satellite failures that have afflicted GEO satellites. Also considered are the general trends in the GEO market and the tendencies of satellite operators to remove their assets from the operational GEO region at the end of their useful life. All of these analyses are brought together in a GEO Simulator, which is designed to determine the collision risk in GEO and the effect that satellite failures, future launch traffic and re-orbiting trends have on this risk. Drawing on this assessment of current and future GEO utilisation, a list of potential ROGER mission scenarios has been generated. For each case the major technical issues are assessed with respect to the available technology, and cost and schedule implications are compared with economic issues such as sources of funding. In this way, cases for government and commercial funding of a ROGER mission are examined. This paper will present examples of such analyses and discuss the rationale behind a possible solution.

Smith, D.; Martin, K. C.; Petersen, H.; Shaw, A.; Skidmore, B.; Smith, D.; Stokes, H.; Willig, A.

301

Analysis of trends between solar wind velocity and energetic electron fluxes at geostationary orbit using the reverse arrangement test  

NASA Astrophysics Data System (ADS)

A correlation between solar wind velocity (VSW) and energetic electron fluxes (EEF) at the geosynchronous orbit was first identified more than 30 years ago. However, recent studies have shown that the relation between VSW and EEF is considerably more complex than was previously suggested. The application of process identification technique to the evolution of electron fluxes in the range 1.8 - 3.5 MeV has also revealed peculiarities in the relation between VSW and EEF at the geosynchronous orbit. It has been revealed that for a constant solar wind density, EEF increase with VSW until a saturation velocity is reached. Beyond the saturation velocity, an increase in VSW is statistically not accompanied with EEF enhancement. The present study is devoted to the investigation of saturation velocity and its dependency upon solar wind density using the reverse arrangement test. In general, the results indicate that saturation velocity increases as solar wind density decreases. This implies that solar wind density plays an important role in defining the relationship between VSW and EEF at the geosynchronous orbit.

Aryan, Homayon; Boynton, Richard J.; Walker, Simon N.

2013-02-01

302

Proposal for a new type of ion tracer experiment using an ion mass spectrometer at the geostationary orbit  

Microsoft Academic Search

A new concept in ion tracer experiments in the magnetosphere is proposed. Barium or lithium ions injected at the foot of the 6.6 R sub E field line by conventional shaped-charge release might be detectable in the equatorial plane by a mass-energy spectrometer of the type to be flown on the GEOS satellite. Comparison of optical and mass-spectrometric detection techniques

D. T. Young

1975-01-01

303

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

304

Aerosol impact on the earth radiation budget with satellite data  

NASA Astrophysics Data System (ADS)

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

Dammann, Knut W.; Hollmann, Rainer; Stuhlmann, Rolf

2000-08-01

305

Scaling of solid state lasers for satellite power beaming applications  

Microsoft Academic Search

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

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

1994-01-01

306

Analise DA Geometria Orbital E Manutencao DA Orbita de Um Satelite de Observacao DA Terra (Analysis of Orbital Geometry and Orbit Maintenance of an Earth Observation Satellite).  

National Technical Information Service (NTIS)

An introduction to a recurring sun-synchronous orbit is given so as to choose adequately an orbit for Earth monitoring satellites. An analysis of choice criteria is made taking into account the hardware of the satellite and the mission constraints. For th...

V. Matosdemedeiros

1987-01-01

307

Detumbling of an Axially Symmetric Satellite with an Orbital Maneuvering Vehicle by Nonlinear Feedback Control.  

National Technical Information Service (NTIS)

The problem of detumbling a freely spinning and precessing axisymmetric satellite is considered. Detumbling is achieved with another axisymmetric orbital maneuvering vehicle (OMV) joined to the target satellite with a universal joint. The joint provides t...

K. R. Fleming

1985-01-01

308

Multicast Routing Algorithms and Failure Analyses for Low Earth Orbit Satellite Communication Networks.  

National Technical Information Service (NTIS)

In the rapidly changing environment of mobile communications, the importance of the mobile satellite (e,g,, low earth orbit satellites (LEOsats)) networks will increase due to their global visibility and connection. Multicasting is an effective communicat...

J. S. Lee

2002-01-01

309

Numerical studies on chaotic planar motion of satellites in an elliptic orbit  

Microsoft Academic Search

The nonlinear planar motion of satellites is investigated here taking into account the effect of eccentricity of the orbit and of the inertia moment ratio of the satellite. The Melnikov method is used to show that the system which describes the dynamic behavior of satellites in planar motion is nonintegrable, and the planar motion of satellites is numerically studied using

Tong Xiao-Hua; Fred P. J. Rimrott

1991-01-01

310

The National Polar-orbiting Operational Environmental Satellite System  

NASA Astrophysics Data System (ADS)

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

Bloom, H.

311

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.

312

Physical and Orbital Properties of Some of Saturn's Small Satellites  

NASA Astrophysics Data System (ADS)

We present Cassini imaging results on the orbits and physical properties for the small ring-region moons Pan, Atlas, and the Cassini-discovered Keeler gap moon, S/2005 S1 (1), as well as the newly discovered/recovered moons orbiting among the major satellites, Methone (S/2004 S1), Pallene (S/2004 S2), and the Dione co-orbital S/2004 S5 Polydeuces (2,3,4). We find that Atlas is undergoing a 700-km amplitude longitudinal perturbation by Prometheus, Methone is undergoing a 30,000-km amplitude longitudinal perturbation by Mimas, and Pallene is undergoing a long-term 75-km amplitude longitudinal perturbation by Enceladus. Orbital integrations involving Atlas return a mass of GMAtlas = (0.43 ± 0.18) X 10-3 km3/sec2, three times larger than previously reported (4). Reasonably high resolution images have also allowed refinement of physical dimensions and spectral properties of these small moons. Results will be presented. At the time of writing, we find that Atlas has polar and equatorial diameters of 19 km, 38 km and 46 km, respectively. Its volume is (1.5 ± 0.4) X 104 km3, yielding a density of 0.43 ± 0.20 gm/cm3. Pan's polar diameter is 23 km, and differences in its equatorial axes are not well constrained; they both appear to be ˜ 35 km. Pan's volume is (1.4 ± 0.7) X 104 km3. Using the most currently reliable mass, GMPan = (0.33 ± 0.05) × 10-3 km3/sec2 (4), Pan's density is roughly 0.4 ± 0.2 gm/cm3. Both Pan and Atlas appear to be synchronous rotators, but libration cannot be ruled out yet. Given its shape, it is possible that Atlas is in a secondary spin-orbit resonance that could force a libration. Preliminary idealized rubble pile simulations have been performed which show that, at the orbits of Atlas and Pan, a simple self-gravitating ice-particle aggregate, with equal equatorial dimensions, would be stable against tides; a body with sufficiently unequal equatorial dimensions would not. [1] IAUC 8524. [2] IAUC 8389. [Correction: Pallene (S/2004 S2) is the same body as S/1981 S14 (IAUC 6162)]. [3] IAUC 8432. [4] Porco et al. 2005, Science, 307, 1226.

Porco, C. C.; Thomas, P.; Spitale, J.; Jacobson, R. A.; Denk, T.; Charnoz, S.; Richardson, D. C.; Dones, L.; Baker, E.; Weiss, J. W.

2005-08-01

313

MAGNETOSPHERIC SUBSTORMS OBSERVED AT THE SYNCHRONOUS ORBIT  

Microsoft Academic Search

The behavior of the magnetic field at the synchronous orbit during magnetospheric substoms is discussed for several events during December 1966 and January 1967. The vector measurements of the field were made with magnetometers on board the geostationary satellite ATS 1. The field was observed to be depressed and inclined radially outward in the dusk-tomidnight quadrant while substorms were in

W. D. Cummings; J. N. Barfield; P. J. Jr. Coleman

1968-01-01

314

Attenuation and scintillation of radio waves in the Earth's atmosphere from radio occultation experiments on satellite-to-  

Microsoft Academic Search

A theoretical analysis of refractive loss of radio waves by the Earth's atmosphere in radio occultation measurements along the satellite-to-satellite line for various altitude profiles of the refractive index is given. Experimental results for refractive loss on the orbital spacecraft - geostationary satellite link are presented. Theoretical calculations are compared with experimental data, and a conclusion is drawn that the

O. I. Yakovlev; I. A. Vilkov

1995-01-01

315

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

316

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.

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

1990-01-01

317

Biaxial Mode of Rotation of a Satellite in the Orbit Plane  

Microsoft Academic Search

A mode of motion of a satellite with respect to its center of mass is studied, which is called the biaxial rotation in the orbit plane. In this mode of rotation, an elongated and nearly dynamically symmetric satellite rotates around the longitudinal axis, which, in turn, rotates around the normal to the plane of an orbit; the angular velocity of

V. I. Vetlov; S. M. Novichkova; V. V. Sazonov; S. Yu. Chebukov

2000-01-01

318

Technical and economic feasibility of telerobotic on-orbit satellite servicing  

Microsoft Academic Search

The aim of this research is to devise an improved method for evaluating the technical and economic feasibility of telerobotic on-orbit satellite servicing scenarios. Past, present, and future telerobotic on-orbit servicing systems and their key capabilities are examined. Previous technical and economic analyses of satellite servicing are reviewed and evaluated. The standard method employed by previous feasibility studies is extended,

Brook Rowland Sullivan

2005-01-01

319

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

320

USING LOW THRUST PROPULSION TO ORBIT CONTROL OF THE LUNAR POLAR SATELLITES  

Microsoft Academic Search

It is well known that lunar satellites in polar orbits suffer a high increase on the eccentricity due to the gravitational perturbation of the Earth. That effect is a natural consequence of the Lidov-Kozai resonance. The final fate of such satellites is the collision with the Moon. Therefore, the control of the orbital eccentricity leads to the control of the

Othon Cabo Winter; Décio Cardozo Mourão; Cristiano Fiorillo Melo; José Leonardo Ferreira

2009-01-01

321

HelioFTH: combining cloud index principles and aggregated rating for cloud masking using infrared observations from geostationary satellites  

NASA Astrophysics Data System (ADS)

In this paper a cloud mask and cloud fractional coverage (CFC) retrieval scheme called HelioFTH is presented. The algorithm is self-calibrating and relies on infrared (IR) window-channel observations only. It needs no input from numerical weather prediction (NWP) or radiative transfer models, nor from other satellite platforms. The scheme is applicable to the full temporal and spatial resolution of the Meteosat Visible and InfraRed Imager (MVIRI) and the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) sensors. The main focus is laid on the separation of middle- and high-level cloud coverage (HCC) from low-level clouds based on an internal cloud-top pressure (CTP) product. CFC retrieval employs a IR-only cloud mask based on an aggregated rating scheme. CTP retrieval is based on a Heliosat-like cloud index for the MVIRI IR channel. CFC from HelioFTH, the International Satellite Cloud Climatology Project (ISCCP) DX and the Satellite Application Facility on Climate Monitoring (CM SAF) were validated with CFC from the Baseline Surface Radiation Network (BSRN) and the Alpine Surface Radiation Budget (ASRB) network. HelioFTH CFC differs by not more than 5-10% from CM SAF CFC but it is higher than ISCCP-DX CFC. In particular the conditional probability to detect cloud-free pixels with HelioFTH is raised by about 35% compared to ISCCP-DX. The HelioFTH CFC is able to reproduce the day-to-day variability observed at the surface. Also, the HelioFTH HCC was inter-compared to CM SAF and ISCCP-DX over different regions and stations. The probability of false detection of cloud-free HCC pixels is in the same order as ISCCP-DX compared to the CM SAF HCC product over the full-disk area. HelioFTH could be used for generating an independent climate data record of cloud physical properties once its consistency and homogeneity is validated for the full Meteosat time series.

Dürr, B.; Schröder, M.; Stöckli, R.; Posselt, R.

2013-08-01

322

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

323

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

324

Observations of the Neupert Effect with the Solar Dynamics Observatory, Reuven Ramaty High Energy Solar Spectroscopic Imager, and Geostationary Operational Environmental Satellite  

NASA Astrophysics Data System (ADS)

The Neupert Effect is an empirically observed correlation between the hard X-rays (HXR) and the time derivative of soft X-rays (SXR) emitted during the impulsive phase of a solar flare. According to standard models of magnetic reconnection driven flares, accelerated electron beams are responsible for creating the HXR Bremsstrahlung radiation in the Transition Region and upper Chromosphere. This energy input should also heat the relatively low-temperature Chromospheric plasma, increasing the intensity of extreme ultraviolet (EUV) emission lines. The launch of the Extreme Ultraviolet Variability Experiment (EVE) on board the Solar Dynamics observatory (SDO) has for the first time provided measurements of the solar irradiance spectra with 0.1 nm spectral resolution over the range 6.5-37 nm at 10-second cadence and nearly 100% duty cycle. Comparisons were made using the EUV spectral data from EVE, SXR measured by the X-Ray Spectrometer (XRS) on the Geostationary Operational Environmental Satellites (GOES), and HXR recorded with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The first focus of the investigation looked at the timing of the HXR, time derivative of soft X-ray, and the Helium-II 304Å doublet. The second focus compared He II images taken by the Atmospheric Imaging Assembly (AIA) (also on SDO) to x-ray images taken by RHESSI to compare the spatial location and area of the lower atmospheric energy emissions. We investigated all M class and above flares between May 1st 2010 and June 1st 2011 with complete coverage by all three instruments totaling 31 events. Of these, 77% (24) showed the expected Neupert Effect with 70% (17) of these events also displaying He-II profiles consistent with the electron beam heating model. This collaboration was organized through the SESI internship program at GSFC and funded by the Catholic University of America.

Schonfeld, Sam J.; Chamberlin, P. C.

2012-01-01

325

ConeXpress Orbital Life Extension Vehicle - a commercial service for communications satellites  

NASA Astrophysics Data System (ADS)

Telecommunications satellites are designed for useful lives of 10-15 years before they are "junked" when their propellant runs out. This is a waste of huge catital investments, because all or most of the satellites' revenue-generating communications payloads is still functional. The ConeXpress Orbital Life Extension Vehicle is a novel spacecraft that will significantly prolong the operating lives of these valuable satellites. Launched aboard Ariane-5, it is designed to dock with a satellite and operate as an orbital "tugboat", supplying the propulsion, navigation and guidance to keep its host in the proper orbital slot for many years of revenue-earning service.

Caswell, Doug; Visentin, Gianfranco; Ortega, Guillermo; de Kam, Jaap; Nugteren, Paul Robert; Scholten, Han

2006-08-01

326

Satellite Orbit Determination Using GPS Carrier Phase in Pure Kinematic Mode  

NASA Astrophysics Data System (ADS)

The mainstream approach to satellite orbit determination has been a dynamic one. This approach is fine as long as the satellite dynamic model is accurate. When the dynamics model is not accurate, the reduced dynamic approach is better suited for orbit determination. Even a purely kinematic solution can be obtained by using the reduced dynamic approach. However, this method is computationally very extensive and still requires a reasonably good satellite dynamics model to compute its reference orbit. A new algorithm and computer program, KODAC (Kinematic Orbit Determination And Comparison), was developed for satellite orbit determination using a kinematic approach with the GPS carrier phase as observable. Since the GPS signal has enough spatial geometric information, it is possible to determine the satellite orbit using a purely kinematic approach. In this method both double and triple differenced GPS carrier phases are used as observables, and epoch by epoch satellite positions and DD ambiguities are estimated by assuming GPS ephemerides and ground station positions are known. TOPEX GPS data is used for this study, and the final radial rms orbit accuracy of 5 cm with respect to the MSODP (Multi Satellite Orbit Determination Program) dynamic solution is achieved. This new kinematic approach has the advantage of having consistent orbit accuracy regardless of satellite altitude. The same algorithm can be applied to any satellite with a GPS receiver due to the algorithm's non-dynamic approach. The TOPEX on-board receiver has only six channels, and its signal view angle is limited. With an improved on-board receiver equipped with more channels and a wider GPS view angle, an improvement in orbit accuracy can be expected for future satellite missions.

Byun, Sung Hun

327

Stability of the cylindrical precession of a satellite in an elliptic orbit  

Microsoft Academic Search

We study the linear problem on the stability of rotation of a dynamically symmetric satellite about the normal to the plane\\u000a of the orbit of its center of mass. The orbit is assumed to be elliptic, and the orbit eccentricity is arbitrary. We assume\\u000a that the Hamiltonian contains a small parameter characterizing the deviation of the satellite central ellipsoid of

A. P. Markeev

2008-01-01

328

World atlas of satellites  

NASA Astrophysics Data System (ADS)

Features of the 17 services offered by planned or operational satellites in geostationary earth orbit (GEO) are described. The orbital inclinations, controlling organizations, and frequency bands employed by the 143 spacecraft in GEO as of 1979 are provided, together with the typical operational parameters of the 6/4 GHz transmitters and receivers. The spacecraft have nominal design lifetimes of 10-15 yr and employ FDM-FM, digital, SCPC, and video transmission techniques. Attention is given to the technology developments affecting GEO satellite system characteristics and the capacity of the GEO. Intersatellite service is characterized, as are frequency allocations and applications, and the space operation service involving frequency bands dedicated to the telemetry, tracking, and telecommand of spacecraft. Consideration is given to mobile satellite services, satellite broadcasting services, and satellite navigation, earth exploration, and positioning services. Finally, meteorological, standard frequency and time signal, and space research satellite services are explored, noting that the latter do not usually use GEO positions.

Jansky, D. M.

329

Satellite failures revisited  

NASA Astrophysics Data System (ADS)

In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

Balcerak, Ernie

2012-12-01

330

MIMOSA—A satellite measuring orbital and attitudinal accelerations caused by non-gravitational forces  

Microsoft Academic Search

MIMOSA is a project of a small satellite carrying a highly sensitive electrostatically compensated accelerometer. The device has been already checked on board two spacecraft; to fully use the properties of the accelerometer a special satellite is prepared to gather data on the non-gravitational forces causing the orbital as well as rotational perturbations of close artificial satellites. The projected sensitivity

L. Sehnal; L. Pospísilová; R. Perestý; P. Dostál; A. Kohlhase

1999-01-01

331

Impact of satellite constellation arrangement on the future orbital debris environment  

Microsoft Academic Search

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

Shin-Yi Su

1997-01-01

332

Experiment Plan of ETS8 in Orbit : Mobile Communications and Navigation  

Microsoft Academic Search

The experiment of S-Band Mobile Communications\\/Broadcasting and L\\/S-Band Satellite Navigation is the main objectives of Engineering Test Satellite - 8 (ETS-8), which will be launched in 2004 into geostationary orbit at 146 degree East. In this paper, the basic experiment plan is described. After the function tests of satellite in orbit, participation of those who have interest in this experiment

M. Homma; S. Hama; H. Kohata

2002-01-01

333

Broadcast satellite service: The international dimension  

NASA Astrophysics Data System (ADS)

The dawn of the 1990's has witnessed the birth of a new satellite service - satellite sound broadcasting. This new service is characterized by digital transmission at data rates up to 256 kb/s from satellites in geostationary orbit to small, low-cost, mobile and portable receivers. The satellite sound broadcasting service is a logical step beyond navigation satellite service, such as that provided by the GPS Navstar system. The mass market appeal of satellite sound broadcasting in the area of lightsat technology and low-cost digital radios has greatly facilitated the financing of this type of space service.

Samara, Noah

1991-09-01

334

Models of Solar Radiation Pressure in the Orbit Determination of GPS Satellites  

NASA Astrophysics Data System (ADS)

For the orbit determination of high-orbit satellites, such as GPS satellites, the largest error source is the perturbation of solar radiation pressure. In recent years, the precision of the GPS ephemerides provided by various IGS analysis centers has been continually improved, for which a very important factor is the continuous refinement of the solar radiation pressure model. After a detailed description of the currently used 7 solar radiation pressure models, they are used to integrate satellite orbits, for the purpose of comparing their accuracies in the orbit integration of GPS satellites. The results show that the 3 models provided by Bern University are the most accurate for simulating the solar radiation pressure, and the obtained GPS orbit precision from them are almost an order of magnitude better than the other 4 models.

Chen, Jun-ping; Wang, Jie-xian

2007-01-01

335

Near-real-time cloud properties and aircraft icing indices from GEO and LEO satellites  

Microsoft Academic Search

Imagers on many of the current and future operational meteorological satellites in geostationary Earth orbit (GEO) and lower Earth orbit (LEO) have enough spectral channels to derive cloud microphysical properties useful for a variety of applications. The products include cloud amount, phase, optical depth, temperature, height and pressure, thickness, effective particle size, and ice or liquid water path, shortwave albedo,

Patrick Minnis; William L. Smith Jr.; Louis Nguyen; Douglas A. Spangenberg; Patrick W. Heck; Rabindra Palikonda; J. Kirk Ayers; Cory Wolff; John J. Murray

2004-01-01

336

Transport protocols for Internet-compatible satellite networks  

Microsoft Academic Search

We address the question of how well end-to-end transport connections perform in a satellite environment composed of one or more satellites in geostationary orbit (GEO) or low-altitude Earth orbit (LEO), in which the connection may traverse a portion of the wired Internet. We first summarize the various ways in which latency and asymmetry can impair the performance of the Internet's

Thomas R. Henderson; Randy H. Katz

1999-01-01

337

Study of aerosol impact on the earth radiation budget with satellite data  

NASA Astrophysics Data System (ADS)

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

Dammann, K. W.; Hollmann, R.; Stuhlmann, R.

338

An international geostationary overlay for GPS and GLONASS  

NASA Astrophysics Data System (ADS)

The concept of employing nonautonomous satellite repeaters on geostationary hosts for civil radionavigation, especially for integrity broadcast and for coverage augmentation, is reviewed. It is suggested that a worldwide geostationary overlay can be more economical than launching additional autonomous navigation satellites. Also presented are recently developed technical considerations for the geostationary overlay concept, including design parameters for the navigation package, signal and data format considerations for augmentation and integrity, and ground network concepts for generating and timing the uplink signal. Early results of a test program being conducted with transmission of GPS-like signals via an existing L-band mobile communications satellite are reported.

Kinal, G. V.; Singh, J. P.

339

The National Polar-orbiting Operational Environmental Satellite System: Capabilities for Atmospheric Remote Sensing for NWP and Climate -- Moving Towards a Global Earth Observation System of Systems  

NASA Astrophysics Data System (ADS)

Over the last decade, the tri-agency Integrated Program Office (IPO), comprised of the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA), has been managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Once operational later this decade, NPOESS will replace NOAA's Polar-orbiting Operational Environmental Satellites (POES) and DoD's Defense Meteorological Satellite Program (DMSP) systems. The IPO, through its Acquisition and Operations contractor, Northrop Grumman, will launch NPOESS spacecraft into three orbital planes to provide a single, national system capable of satisfying both civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving the existing "weather" satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - ocean, atmosphere, land, and the space environment. The NPOESS will enable more accurate short-term weather forecasts and severe storm warnings and improved monitoring of atmospheric phenomena. NPOESS will also provide continuity of critical data for monitoring, understanding, and predicting climate change and assessing the impacts of climate change on seasonal and longer time scales. For these purposes, the NPOESS Integrated Program Office [IPO] is developing a suite of advanced, atmospheric sounding/probing instruments as a major part of the next generation meteorological, environmental and climate operational satellite system in polar, low earth orbit [LEO]. The IPO is developing the CrIS, Cross-track Infrared Sounder, an Ozone Mapping & Profiler Suite [OMPS]and a Visible and Infrared Imager and Radiometer Suite [VIIRS] and NASA is developing an Advanced Technology Microwave Sounder [ATMS]. These four instruments will be key parts of the NPOESS operational satellite system and its precursor, bridging and risk-reduction mission - the NPOESS Preparatory Project [NPP]. The CrIS/ATMS/OMPS (& VIIRS) and, later on NPOESS, a Conical-scanning Microwave Imager and Sounder [CMIS] will represent a USA highly capable, complementary sounding and imaging suite for the next generation. In the same time frame the European community, EUMETSAT, European Organization for the Exploitation of Meteorological Satellite Systems, will be flying their next generation, operational, polar-orbiting LEO system, METOP. METOP will have a highly capable FTS sounder, IASI [Infrared Atmospheric Sounder Interferometer], an Advanced Microwave Sounding Unit [AMSU], a Global Ozone Monitoring Experiment [GOME-2], a GNSS Receiver for Atmospheric Sounding [GRAS]and an Advanced Very High Resolution Radiometer [AVHRR]. The NPOESS & METOP sounders and imagers will represent a significant contribution to a polar-orbiting, atmospheric sounding and imaging component of an emerging Global Earth Observation System of Systems [GEOSS] for NWP and Climate. Similarly the Geostationary Operational Environmental Satellite System [GOES-R] & Meteosat Second Generation [MSG] sounders and imagers will represent an important geostationary component of such a GEOSS.

Mango, S. A.; Hinnant, F.; Hoffman, C. W.; Smehil, D. L.; Schneider, S. R.; Simione, S.; Needham, B.; Stockton, D.

2005-12-01

340

Biaxial Mode of Rotation of a Satellite in the Orbit Plane  

NASA Astrophysics Data System (ADS)

A mode of motion of a satellite with respect to its center of mass is studied, which is called the biaxial rotation in the orbit plane. In this mode of rotation, an elongated and nearly dynamically symmetric satellite rotates around the longitudinal axis, which, in turn, rotates around the normal to the plane of an orbit; the angular velocity of rotation around the longitudinal axis is several times larger than the orbital angular velocity, deviations of this axis from the orbit plane are small. Such a rotation is convenient in the case when it is required to secure a sufficiently uniform illumination of the satellite's surface by the Sun at a comparatively small angular velocity of the satellite. The investigation consists of the numerical integration of equations of the satellite's motion, which take into account gravitational and restoring aerodynamic moments, as well as the evolution of the orbit. At high orbits, the mode of the biaxial rotation is conserved for an appreciable length of time, and at low orbits it is destroyed due to the impact of the aerodynamic moment. The orbit altitudes and the method of constructing the initial conditions of motion that guarantee a sufficiently prolonged period of existence of this mode are specified.

Vetlov, V. I.; Novichkova, S. M.; Sazonov, V. V.; Chebukov, S. Yu.

2000-11-01

341

Development of Integrated Orbit and Attitude Software-in-the-loop Simulator for Satellite Formation Flying  

NASA Astrophysics Data System (ADS)

An integrated orbit and attitude control algorithm for satellite formation flying was developed, and an integrated orbit and attitude software-in-the-loop (SIL) simulator was also developed to test and verify the integrated control algorithm. The integrated algorithm includes state-dependent Riccati equation (SDRE) control algorithm and PD feedback control algorithm as orbit and attitude controller respectively and configures the two algorithms with an integrating effect. The integrated SIL simulator largely comprises an orbit SIL simulator for orbit determination and control, and attitude SIL simulator for attitude determination and control. The two SIL simulators were designed considering the performance and characteristics of related hardware-in-the-loop (HIL) simulators and were combined into the integrated SIL simulator. To verify the developed integrated SIL simulator with the integrated control algorithm, an orbit simulation and integrated orbit and attitude simulation were performed for a formation reconfiguration scenario using the orbit SIL simulator and the integrated SIL simulator, respectively. Then, the two simulation results were compared and analyzed with each other. As a result, the user satellite in both simulations achieved successful formation reconfiguration, and the results of the integrated simulation were closer to those of actual satellite than the orbit simulation. The integrated orbit and attitude control algorithm verified in this study enables us to perform more realistic orbit control for satellite formation flying. In addition, the integrated orbit and attitude SIL simulator is able to provide the environment of easy test and verification not only for the existing diverse orbit or attitude control algorithms but also for integrated orbit and attitude control algorithms.

Park, Han-Earl; Park, Sang-Young; Park, Chandeok; Kim, Sung-Woo

2013-03-01

342

A Polynomial Force Model Representation for Determining Near-Equatorial, Near-Synchronous Satellite Orbits.  

National Technical Information Service (NTIS)

A method for accurately determining the orbits of near-equatorial, near-synchronous satellites is presented. The basic approach is to supplement the conventional spherical harmonics representation of the terrestrial gravity field with a forcing function h...

N. S. Hall R. H. Gersten

1968-01-01

343

POLAR-ORBITING ENVIRONMENTAL SATELLITES: Status, Plans, and Future Data Management Challenges.  

National Technical Information Service (NTIS)

In summary, today's polar-orbiting weather satellite program is essential to a variety of civilian and military operations, ranging from weather warnings and forecasts to specialized weather products. NPOESS is expected to merge today's two separate satel...

L. D. Koontz

2002-01-01

344

Reducing the Error Growth in the Numerical Propagation of Satellite Orbits.  

National Technical Information Service (NTIS)

An algorithm especially designed for the long term numerical integration of perturbed oscillators, in one or several frequencies, is presented. The method is applied to the numerical propagation of satellite orbits, using focal variables, and the results ...

J. M. Ferrandiz J. Vigo P. Martin

1991-01-01

345

Advanced Identification Techniques Applied to Validation of Satellite Attitude and Orbit Control Systems.  

National Technical Information Service (NTIS)

An essential activity during the integration of satellite hardware is the estimation and validation of the dynamic characteristics of the Attitude and Orbit Control System (AOCS), to prove that units interface as required and to demonstrate the robustness...

R. Marley

1991-01-01

346

Stability of planar oscillations of a satellite in an elliptic orbit  

Microsoft Academic Search

A problem of stability of odd 2p-periodic oscillations of a satellite in the plane of an elliptic orbit of arbitrary eccentricity is considered. The motion is supposed to be only under the influence of gravitational torques.

V. A. Zlatoustov; A. P. Markeev

1973-01-01

347

Comparison Between Low Circular and Elliptical Inclined Orbits for Small Satellites Communication Applications.  

National Technical Information Service (NTIS)

Some results of a system study concerning the performance of large constellations of small satellites in low circular and inclined elliptical orbits for real time communications are presented. Performances are evaluated in terms of visibility and mutual c...

G. Perrotta

1991-01-01

348

On-Orbit System Identification Experiments of the Engineering Test Satellite-VIII  

Microsoft Academic Search

This paper presents the results of on-orbit system identification of the Engineering Test Satellite-VIII (ETS-VIII), which was launched by the H-IIA Launch Vehicle No. 11 in December 2006. On-orbit system identification experiments were performed using data acquired during normal operations in the initial check-out phase, such as station acquisition and wheel unloading. The satellite's unconstrained modes were identified using attitude

Tokio Kasai; Isao Yamaguchi; Hirotaka Igawa; Shinji Mitani; Takashi Ohtani; Masafumi Ikeda; Kei Sunagawa

2009-01-01

349

Attenuation and scintillation of radio waves in the Earth's atmosphere from radio occultation experiments on satellite-to-satellite links  

Microsoft Academic Search

A theoretical analysis of refractive loss of radio waves by the Earth's atmosphere in radio occultation measurements along the satellite-to-satellite line for various altitude profiles of the refractive index is given. Experimental results for refractive loss on the orbital spacecraft-geostationary satellite link are presented. Theoretical calculations are compared with experimental data, and a conclusion is drawn that the signal amplitude

O. I. Yakovlev; S. S. Matyugov; I. A. Vilkov

1995-01-01

350

Comparison of the Selected Geopotential Models in Terms of the GOCE Satellite Orbit Computation  

NASA Astrophysics Data System (ADS)

In this work, the chosen geopotential models are evaluated in the aspect of the orbit modelling of the Gravity Field and Steady-State Ocean Circulation Explorer Mission (GOCE) satellite. Selected gravity field models include, among other things, the recent models from the GOCE mission and the models such as EIGEN-51C, AIUB-CHAMP03S, ITG-Grace2010s, EIGEN-5C, EGM2008, EGM96. An essential tool for comparing different geopotential models is the Torun Orbit Processor (TOP) software package, which is based on the Cowell 8th order numerical integration method. The TOP software generates a satellite orbit in the field of gravitational and non-gravitational forces (including the relativistic and empirical accelerations). The 1-day orbital arcs were computed using various geopotential models. The first set of the root mean squares (RMSs) of the differences between the satellite positions on the computed orbits and on the reference orbit was obtained. The reference orbit was the 1-day arc of the reduced-dynamic Precise Science Orbit (PSO rd) of the GOCE satellite delivered by the European Space Agency. In addition, the coefficients of given models were modified using the normal distribution, taking into account their standard deviations. Using such modified geopotential models, the corresponding orbital arcs were determined. Thus, the second set of the RMS parameters of the differences between the orbital arcs based on the modified models and the corresponding arcs without the modification of models was obtained. Both mentioned sets of RMS parameters were used to compare the geopotential models according to two criteria; the external one - fitting the computed orbit to the reference orbit, the internal one - the effect of the estimation errors of the gravity field coefficients on the orbit error.

Bobojc, A.; Drozyner, A.

2012-04-01

351

ORBITS AND MASSES OF THE SATELLITES OF THE DWARF PLANET HAUMEA (2003 EL61)  

SciTech Connect

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 Keplerian orbit is sufficient to describe the motion of the inner, fainter satellite Namaka. Using a fully interacting three-point-mass model, we have recovered the orbital parameters of both orbits and the mass of Haumea and Hi'iaka; Namaka's mass is marginally detected. The data are not sufficient to uniquely determine the gravitational quadrupole of the nonspherical primary (described by J {sub 2}). The nearly coplanar nature of the satellites, as well as an inferred density similar to water ice, strengthen the hypothesis that Haumea experienced a giant collision billions of years ago. The excited eccentricities and mutual inclination point to an intriguing tidal history of significant semimajor axis evolution through satellite mean-motion resonances. The orbital solution indicates that Namaka and Haumea are currently undergoing mutual events and that the mutual event season will last for next several years.

Ragozzine, D.; Brown, M. E. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)], E-mail: darin@gps.caltech.edu

2009-06-15

352

THE ORBITS OF THE NEPTUNIAN SATELLITES AND THE ORIENTATION OF THE POLE OF NEPTUNE  

SciTech Connect

This paper reports on an update to the orientation of Neptune's pole and to the orbits of the Neptunian satellites, Triton, Nereid, and Proteus. We determined the new pole and orbits in the International Celestial Reference Frame by fitting them to all available observations through the opposition of 2008. The new data in the fit are high-quality modern astrometry and constitute a 19 year extension of the previous data arc. We assess the accuracy of the orbits and compare them with our earlier orbits. We also provide mean elements as a geometrical description for the orbits.

Jacobson, R. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)], E-mail: robert.jacobson@jpl.nasa.gov

2009-05-15

353

The Orbits of the Neptunian Satellites and the Orientation of the Pole of Neptune  

NASA Astrophysics Data System (ADS)

This paper reports on an update to the orientation of Neptune's pole and to the orbits of the Neptunian satellites, Triton, Nereid, and Proteus. We determined the new pole and orbits in the International Celestial Reference Frame by fitting them to all available observations through the opposition of 2008. The new data in the fit are high-quality modern astrometry and constitute a 19 year extension of the previous data arc. We assess the accuracy of the orbits and compare them with our earlier orbits. We also provide mean elements as a geometrical description for the orbits.

Jacobson, R. A.

2009-05-01

354

Study of Double Gimballed Momentum Wheels in the Attitude and Orbit Control System of a Geostationary Communication Satellite.  

National Technical Information Service (NTIS)

The potentials of a double gimballed momentum wheel as an actuator for attitude control are discussed with respect to the related subsystems. A comparison is made between possible attitude control systems (hybrid, active, semiactive systems) to obtain the...

G. Boersma F. J. Sonnenschein

1975-01-01

355

A satellite-tracking K- and Ka-band mobile vehicle antenna system  

Microsoft Academic Search

This paper describes the development of the K- and Ka-band, satellite-tracking mobile-vehicular antenna system for NASA's ACTS Mobile Terminal (AMT) project. ACTS is NASA's Advanced Communications Technology Satellite, which will be launched into its geostationary orbit in September 1993. The AMT task will make the first experimental use of the satellite soon after the satellite is operational, to demonstrate mobile

Arthur C. Densmore; Vahraz Jamnejad

1993-01-01

356

MODELLING OF INTERFERENCE CAUSED BY UPLINK SIGNAL FOR LOW EARTH ORBITING SATELLITE GROUND STATIONS  

Microsoft Academic Search

Microsatellites in Low Earth Orbits (LEO) have been in use for the past two decades. Low Earth Orbit satellites are used for public communication and also for scientific purposes. Thus, it may be expected that such missions will be further developed in the near future especially in fields where similar experiments by purely Earth-based means are impracticable. Ground stations have

Shkelzen Cakaj; Arpad L. Scholtz

357

Long-term collision risk prediction for low earth orbit satellite constellations  

Microsoft Academic Search

In the light of recent changes to planned Low Earth Orbit (LEO) satellite constellation designs and enhancements made to the DERA IDES model, we have conducted a new study on long-term debris environment evolution. This includes the collision interactions of constellation systems with the orbital debris environment over the next 50 years. In this new study, we use the IDES

G. G. Swinerd; P. H. Stokes; J. E. Wilkinson

2000-01-01

358

Precise orbit determination and gravity field improvement for the ERS satellites  

Microsoft Academic Search

The radial orbit error has long been the major error source in ERS-1 altimetry, crippled by having only satellite laser ranging for precise tracking and relying on insufficiently accurate general-purpose gravity field models. Altimeter crossovers are used very effectively as additional tracking data to laser ranging. The ERS Tandem Mission even provides the unique possibility to simultaneously determine orbits of

Remko Scharroo; Pieter Visser

1998-01-01

359

Study of Advanced Satellite Concept Using a Multifeed Reconfigurable Antenna.  

National Technical Information Service (NTIS)

Towerless single and dual reflector antennas with 2.5 to 3.5 m circular aperture are studied for use on board medium-size geostationary communication satellites (up to 2 tons in transfer orbit) to be launched in Ariane 4 bottom position, SPELDA 10, on the...

E. Frisch H. J. Steiner N. Schroeder R. King C. Carnebianca

1986-01-01

360

Orbit and Attitude Determination Results During Launch Support Operations for SBS-5. (Satellite Business Systems).  

National Technical Information Service (NTIS)

Presented are orbit and attitude determination results from the launch of Satellite Business Systems (SBS)-5 satellite on September 8, 1988 by Arianespace. SBS-5 is a (HS-376) spin stabilized spacecraft. The launch vehicle injected the spacecraft into a l...

K. R. Hartman P. J. Iano

1989-01-01

361

Space system visualization and analysis using the Satellite Orbit Analysis Program (SOAP)  

Microsoft Academic Search

The Satellite Orbit Analysis Program (SOAP) is an interactive software system which employs 3D graphics animation to display the relative motion of satellites, airplanes, ships, and ground stations. Users may construct coordinate systems, sensor shapes, and wireframe spacecraft models. A variety of XY plots and data reports may also be generated. SOAP provides analysis, visualization, and simulation capabilities that can

David Y. Stodden; Gina D. Galasso

1995-01-01

362

Variable structure control for satellite attitude stabilization in elliptic orbits using solar radiation pressure  

Microsoft Academic Search

The paper proposes the use of solar radiation pressure for satellite attitude control in elliptic orbits based on variable structure control. The system comprises of a satellite with two-oppositely placed solar flaps. Sliding mode control and terminal sliding mode control techniques have been adopted to develop nonlinear control laws for suitably rotating the control solar flaps to neutralize the adverse

T. R. Patel; K. D. Kumar; K. Behdinan

2009-01-01

363

Open-loop satellite librational control in elliptic orbits through tether  

Microsoft Academic Search

The paper proposes the use of a bitethered pendulum mass deployed from satellite for open-loop satellite attitude control in elliptic orbits. A simple approximate analytical approach has been adopted to develop control law governing moments generated through a judicious non-feedback scheme of tether length variation with a view to neutralize the adverse effect of the harmonic excitation induced by eccentricity.

K. Kumar

1997-01-01

364

Telemetry and telecommand requirements for future synchronous orbit communications satellites  

Microsoft Academic Search

Requirements on telemetry and command are discussed from the satellite operations point of view. Requirements that lead to good visibility and control of the various satellite functions and enable the monitoring and control of the satellites to be computer-controlled are presented. Autonomous functions (on-board vs on-ground) are discussed, as are pros and cons on fixed and reconfigurable telemetry formats. The

Erland Magnusson

1989-01-01

365

Tomography from a Canadian small satellite in low Earth orbit  

Microsoft Academic Search

All traditional satellite instrumentation designed to look at the atmosphere essentially collect image data. The single-pixel photometer observing the atmosphere in a cartwheel mode is providing a one-dimensional image along the satellite track. A two-dimensional image can be constructed essentially by using the satellite motion to provide a raster scan. In these cases the images are treated as flat, with

E. J. Llewellyn; W. S. C. Brooks; I. C. McDade; D. W. Johnson

1993-01-01

366

Comparison of low-Earth-orbit satellite attitude controllers submitted to controllability constraints  

Microsoft Academic Search

A rule-based fuzzy controller is presented and compared with an adaptive MIMO LQR controller in a low-earth-orbit small satellite attitude control system. The attitude is passively gravity gradient stabilized and actively three-axis magnetorquer controlled. This method insures an earth-pointing satellite making use of a nondepletable and nonmechanical means of control. A realistic simulation environment, using a nonlinear satellite dynamic model

Willem H. Steyn

1994-01-01

367

Low Earth-orbit store-and-forward satellites in the amateur radio service  

Microsoft Academic Search

Several aspects of the most recently launched low-earth-orbit (LEO) store-and-forward satellites operating in the amateur satellite service are described. Included are a description of the satellites and their most interesting implementation details, with particular emphasis on the communications system; a description of the file server and broadcast protocol; a description of operation from the user's viewpoint; and some statistics characterizing

Robert J. Diersing; Greg Jones

1993-01-01

368

The study of gravity gradient effect on attitude of low earth orbit satellite  

NASA Astrophysics Data System (ADS)

Simulations and mathematical models are increasingly used to assist the process of decision making in engineering design. The objective of this paper is to simulate the linear attitude dynamics of small satellites under gravity gradient torque which is inherent in low earth orbit. The equations were first derived in their nonlinear form, and then manipulated and simulated in their linear form. Simulation results demonstrate the importance of choosing the appropriate values of satellite's moment of inertia in designing phase of a satellite.

Hamzah, Nor Hazadura; Yaacob, Sazali; Muthusamy, Hariharan; Hamzah, Norhizam; Ghazali, Najah

2013-04-01

369

ROSETTA mission: satellite orbits around a cometary nucleus  

Microsoft Academic Search

This paper discusses the problem of orbiting a comet nucleus from a perspective of orbital stability. The main forces perturbing the motion of the spacecraft around the comet: shape and rotation rate of the nucleus, comet outgassing, solar radiation pressure; are derived and quantified for the nominal case of the ROSETTA spacecraft at the comet Wirtanen. Their effects on the

D. J. Scheeres; F. Marzari; L. Tomasella; V. Vanzani

1998-01-01

370

Orbit determination error analysis for satellite-satellite\\/ground tracking systems  

Microsoft Academic Search

A statistical error analysis was made for the orbit determination process, where the observations from ground stations and\\/or from some orbiting spacecrafts, employed for tracking, are used. The various errors included in the analysis are errors in the tracking systems, uncertainty in the orbit model, inaccuracies of the ground station coordinates, and errors in the orbital elements of the tracking

C. K. Rajasingh

1977-01-01

371

A new international geostationary electron model: IGE-2006, from 1 keV to 5.2 MeV  

NASA Astrophysics Data System (ADS)

Département Environnement Spatial, Office National d'Etudes et de Recherches Aérospatiales (ONERA) has been developing a model for the geostationary electron environment since 2003. Until now, this model was called Particle ONERA-LANL Environment (POLE), and it is valid from 30 keV up to 5.2 MeV. POLE is based on the full complement of Los Alamos National Laboratory geostationary satellites, covers the period 1976-2005, and takes into account the solar cycle variation. Over the period 1976 to present, four different detectors were flown: charged particle analyzer (CPA), synchronous orbit particle analyzer (SOPA), energetic spectra for particles (ESP), and magnetospheric plasma analyzer (MPA). Only the first three were used to develop the POLE model. Here we extend the energy coverage of the model to low energies using MPA measurements. We further include the data from the Japanese geostationary spacecraft, Data Relay Test Satellite (DRTS). These data are now combined into an extended geostationary electron model which we call IGE-2006.

Sicard-Piet, A.; Bourdarie, S.; Boscher, D.; Friedel, R. H. W.; Thomsen, M.; Goka, T.; Matsumoto, H.; Koshiishi, H.

2008-07-01

372

Radial mixing in the outer Milky Way disc caused by an orbiting satellite  

NASA Astrophysics Data System (ADS)

Using test particle simulations, we examine the structure of the outer Galactic disc as it is perturbed by a satellite in a tight eccentric orbit about the Galaxy. A satellite of mass a few times 109Msolar can heat the outer Galactic disc, excite spiral structure and a warp and induce streams in the velocity distribution. We examine particle eccentricity versus the change in mean radius between initial and current orbits. Correlations between these quantities are reduced after a few satellite pericentre passages. Stars born in the outer galaxy can be moved in radius from their birth positions and be placed in low eccentricity orbits inside their birth radii. We propose that mergers and perturbations from satellite galaxies and subhaloes can induce radial mixing in the stellar metallicity distribution.

Quillen, A. C.; Minchev, Ivan; Bland-Hawthorn, Joss; Haywood, Misha

2009-08-01

373

Sampling uncertainty in satellite rainfall estimates  

NASA Astrophysics Data System (ADS)

Accurate estimates of global precipitation patterns are essential for a better understanding of the hydrological cycle. Satellite observations allow for large scale estimates of rainfall intensities. Uncertainties in current satellite based rainfall estimates are due to uncertainties in the retrieval process as well as the different temporal and spatial sampling patterns of the observation systems. The focus of this study is set on analyzing sampling associated uncertainty for thirteen low Earth orbiting satellites carrying microwave instruments suitable for rainfall measurement. Satellites were grouped by the types of microwave sensors, where NOAA satellites with cross-track sounders and DMSP satellites with conical scanners make the core part of the constellations. The effect of three hourly geostationary measurements on the sampling uncertainty was evaluated as well. A precise orbital model SGP4 was used to generate realistic satellite overpasses database where orbital shifts are taken into account. Using the overpasses database we resampled rain gauge timeseries to simulate satellites rainfall estimates free of retrieval and calibration errors. We look at two regions, Germany and Benin, areas with different precipitation regimes . Our analysis show that sampling uncertainty for all available satellites may differ up to 100% for different latitudes and precipitation regimes. However the performance of various satellite groups is similar to each other, with greater differences in higher latitudes. Addition of three hourly geostationary observations reduces the sampling uncertainty but only to a limited extent.

Itkin, M.; Loew, A.

2012-04-01

374

Speckle Interferometry. I. A Test on an Earth Orbital Satellite.  

National Technical Information Service (NTIS)

The atronomical technique known as speckle interferometry shows considerable promise for satellite surveillance and imaging. With speckle interferometry, it is possible to remove image degradation caused by atmospheric turbulence. In this way, resolution ...

S. P. Worden E. K. Hege E. N. Hubbard N. J. Woolf P. A. Strittmatter

1982-01-01

375

Geostationary Operational Environmental Statellite(GEOS-N report)  

NASA Astrophysics Data System (ADS)

The Advanced Missions Analysis Office (AMAO) of GSFC has completed a study of the Geostationary Operational Environmental Satellites (GOES-N) series. The feasibility, risks, schedules, and associated costs of advanced space and ground system concepts responsive to National Oceanic and Atmospheric Administration (NOAA) requirements were evaluated. The study is the first step in a multi-phased procurement effort that is expected to result in launch ready hardware in the post 2000 time frame. This represents the latest activity of GSFC in translating meteorological requirements of NOAA into viable space systems in geosynchronous earth orbits (GEO). GOES-N represents application of the latest spacecraft, sensor, and instrument technologies to enhance NOAA meteorological capabilities via remote and in-situ sensing from GEO. The GOES-N series, if successfully developed, could become another significant step in NOAA weather forecasting space systems, meeting increasingly complex emerging national needs for that agency's services.

1991-12-01

376

Impact of GPS satellite antenna offsets on GPS-based precise orbit determination  

NASA Astrophysics Data System (ADS)

Since the successful demonstration of GPS-based Precise Orbit Determination (POD) on TOPEX/Poseidon in 1992, GPS-based POD for Low-Earth Orbiters (LEO) such as the CHAMP and GRACE satellites has become a popular method. The orbit accuracy of GPS-based POD has been improved from 3 cm to 1 cm in the radial direction. In order to achieve higher-accuracy results, it is necessary to understand and try to reduce the impact of various error sources on the orbits. One of them is the GPS satellite antenna offset. Currently, most GPS data processing institutions are using relative GPS satellite antenna offsets, and there are big differences (meter level) between the antenna offsets. In addition, accurate antenna offset values can be only estimated from processing GPS data currently with an accuracy of cm to dm levels. In this paper, we studied the impact of GPS satellite antenna offsets on GPS-based POD using the different offsets. The results show that the antenna offsets have large effects (a few cm) on the GPS onboard receiver antenna estimation and relatively small effects (about one cm) on the satellite orbit accuracy.

Kang, Z.; Tapley, B.; Ries, J.; Bettadpur, S.; Nagel, P.

377

Precise Ground-In-the-Loop Orbit Control for Low Earth Observation Satellites  

NASA Astrophysics Data System (ADS)

The growing interest in earth observation missions equipped with space-borne optical and synthetic aperture radar (SAR) sensors drives the accuracy requirements with respect to orbit determination and control. Especially SAR interferometry with its capability to resolve the velocity of on-ground objects (e.g. for traffic monitoring, ocean currents and glacier monitoring) and to determine highly precise digital elevation models is of significant interest for scientific applications. These goals may be achieved using along-track and repeat-pass interferometry with a satellite formation, based on the precise orbit control of one satellite with respect to the osculating trajectory of the second satellite. Such a control concept will be realized by the German TerraSAR-X mission, with an expected launch in 2006, using a virtual formation, where a single satellite will be controlled in a tight manner with respect to a predefined osculating reference trajectory. This is very challenging, since common orbit disturbances, like for close twin formations, do not cancel out in this scenario. The predefined trajectory in the TerraSAR-X case could also be the orbit of a second satellite. The paper describes the generation of such a virtual reference orbit, discusses the ground-in-the-loop control concept and presents results from a long-term simulation.

Arbinger, C.; D'Amico, S.; Eineder, M.

378

Evaluation of the Influence of zonal and sectorial harmonics in the orbit of an lunar satellite  

NASA Astrophysics Data System (ADS)

Abstract (2,250 Maximum Characters): A study evaluating the influence of the lunar gravity potential on the orbit of an artificial satellite is performed varying the values for degree and order from 1 to 100. The gravitational potential is modeled using spherical harmonics according to the model presented in Konopliv (2001). This model provides the components x, y and z for the gravity acceleration at each position of the satellite along the orbit. Comparing the gravity acceleration from a central field and the gravitational acceleration provided by Konopliv the disturbing velocity increment applied to the vehicle is obtained, and hence the Keplerian elements of perturbed orbit of the satellite are calculated allowing the analysis of the orbital motion. Maneuvers of correction and maneuvers of transfer for lunar satellites are simulated considering disturbances due to non-uniformity of the Moon gravitational potential in order to control the trajectory using a continuous propulsion system controlled in close loop. The behavior along the time of the orbital elements, fuel consumption and thrust applied to the satellite are analyzed.

Dias Gonçalves, Liana; Marconi Rocco, E.; Vilhena de Moraes, R.; Prado, A.

2013-05-01

379

GeoSTAR: a geostationary microwave sounder for the future  

NASA Astrophysics Data System (ADS)

The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new Earth remote sensing instrument concept that has been under development at the Jet Propulsion Laboratory. First conceived in 1998 as a NASA New Millennium Program mission and subsequently developed in 2003-2006 as a proof-of-concept prototype under the NASA Instrument Incubator Program, it is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. The importance of such observations have been recognized by the National Academy of Sciences National Research Council, which recently released its report on a "Decadal Survey" of NASA Earth Science activities. One of the recommended missions for the next decade is a geostationary microwave sounder. GeoSTAR is well positioned to meet the requirements of such a mission, and because of the substantial investment NASA has already made in GeoSTAR technology development, this concept is fast approaching the necessary maturity for implementation in the next decade. NOAA is also keenly interested in GeoSTAR as a potential payload on its next series of geostationary weather satellites, the GOES-R series. GeoSTAR, with its ability to map out the three-dimensional structure of temperature, water vapor, clouds, precipitation and convective parameters on a continual basis, will significantly enhance our ability to observe hurricanes and other severe storms. In addition, with performance matching that of current and next generation of low-earth-orbiting microwave sounders, GeoSTAR will also provide observations important to the study of the hydrologic cycle, atmospheric processes and climate variability and trends. In particular, with GeoSTAR it will be possible to fully resolve the diurnal cycle. We discuss the GeoSTAR concept and basic design, the performance of the prototype, and a number of science applications that will be possible with GeoSTAR. The work reported on here was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.

Lambrigtsen, B. H.; Brown, S. T.; Dinardo, S. J.; Gaier, T. C.; Kangaslahti, P. P.; Tanner, A. B.

2007-10-01

380

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

NASA Astrophysics Data System (ADS)

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

Dammann, Knut W.; Hollmann, Rainer; Stuhlmann, Rolf

2001-02-01

381

Irregular Satellites of the Outer Planets: Orbital Uncertainties and Astrometric Recoveries in 2009-2011  

NASA Astrophysics Data System (ADS)

More than 100 small satellites have been identified orbiting the giant planets in distant, inclined, eccentric orbits. Detailed study of these objects requires that their orbits be known well enough to permit routine observations both from the Earth and from spacecraft. Unfortunately, many of the satellites have very poorly known orbits due to a scarcity of astrometric measurements. We have developed a reliable method to estimate the future on-sky position uncertainties of the satellites and have verified that those uncertainties provide a correct measure of the true on-sky positional uncertainty. Based on the uncertainties, we identified a set of satellites that are effectively "lost" and another set that would be lost if additional observations were not obtained in the near future. We attempted recoveries of 26 of the latter group using the Hale 5 m and CFHT 3.6 m telescopes and found 23. This validated our method's predictions and led to significant improvements in our knowledge of the orbits of the recovered moons. There remains a handful of irregular moons which are recoverable and whose orbits will benefit from additional observations during the next decade, while 16 moons of Jupiter and Saturn are essentially lost and will require a re-survey to be located again.

Jacobson, R.; Brozovi?, M.; Gladman, B.; Alexandersen, M.; Nicholson, P. D.; Veillet, C.

2012-11-01

382

Filamentary accretion cannot explain the orbital poles of the Milky Way satellites  

NASA Astrophysics Data System (ADS)

Several scenarios have been suggested to explain the phase-space distribution of the Milky Way (MW) satellite galaxies in a disc of satellites (DoS). To quantitatively compare these different possibilities, a new method analysing angular momentum directions in modelled data is presented. It determines how likely it is to find sets of angular momenta as concentrated and as close to a polar orientation as is observed for the MW satellite orbital poles. The method can be easily applied to orbital pole data from different models. The observed distribution of satellite orbital poles is compared to published angular momentum directions of subhaloes derived from six cosmological state-of-the-art simulations in the Aquarius project. This tests the possibility that filamentary accretion might be able to naturally explain the satellite orbits within the DoS. For the most likely alignment of main halo and MW disc spin, the probability to reproduce the MW satellite orbital pole properties turns out to be less than 0.5 per cent in the Aquarius models. Even an isotropic distribution of angular momenta has a higher likelihood to produce the observed distribution. The two Via Lactea cosmological simulations give results similar to the Aquarius simulations. Comparing instead with numerical models of galaxy interactions gives a probability of up to 90 per cent for some models to draw the observed distribution of orbital poles from the angular momenta of tidal debris. This indicates that the formation as tidal dwarf galaxies in a single encounter is a viable, if not the only, process to explain the phase-space distribution of the MW satellite galaxies.

Pawlowski, M. S.; Kroupa, P.; Angus, G.; de Boer, K. S.; Famaey, B.; Hensler, G.

2012-07-01

383

Penumbra effects on orbital motion of GNSS satellites and their impact on climate investigations  

NASA Astrophysics Data System (ADS)

The tremendous improvement of the gravity field models which we are achieving with the last recovering 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 a 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 (GF-free) can magnify the solar radiation pressure acting on MEO satellites ( GPS, Etalon and, in near real future GALILEO) and its smooth modulation through the Earth's atmosphere (penumbra). We would remind that The GF-free 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 recompute the signal features of penumbra by applying more refined atmospheric models. Finally it is proposed to modify the orbital injection of at least one GALILEO satellite just to magnify penumbra effects on it

Vespe, Francesco

384

Interpretations of de-orbit, deactivation, and shutdown guidelines applicable to GEO satellites  

NASA Astrophysics Data System (ADS)

As the population of space debris in orbit around the Earth grows, the probability for catastrophic collisions increases. Many agencies such as the IADC, FCC, and UN have proposed space debris mitigation guidelines or recommendations. For example, a minimum increase in perigee altitude of 235km + (1000 Cr A / m) where Cr is the solar radiation pressure coefficient, A/m is the aspect area to dry mass ratio, and 235 km is the sum of the upper altitude of the geostationary orbit (GEO) protected region (200 km) and the maximum descent of a re-orbited spacecraft due to lunar-solar & geopotential perturbations (35 km) with an eccentricity less than or equal to 0.003. While this particular recommendation is reasonably straightforward, the assumptions an operator chooses may change the result by 25 km. Other recommendations are more ambiguous. For example, once the space vehicle has been de-orbited to the required altitude, all on-board stored energy sources must be discharged by venting propellants and pressurants, discharging batteries and disabling the ability to charge them, and performing other appropriate measures. “ Vented” is not usually defined. In addition, the broadcasting capability of the spacecraft must be disabled. Boeing and its customers are working together to devise de-orbit and deactivation sequences that meet the spirit of the recommendations. This paper derives and proposes a generic minimum deorbit altitude, appropriate depletion and venting pressures based on tank design, propellant and pressurant type, and an acceptable shutdown procedure and final configuration that avoid interference with those still in the GEO belt well into the future. The goal of this paper is to open a dialogue with the global community to establish reasonable guidelines that are straightforward, safe, and achievable before an absolute requirement is set.

Honda, L.; Perkins, J.; Sun, Sheng

385

Mars network: a Mars orbiting communications and navigation satellite constellation  

Microsoft Academic Search

Mars has become the focus of an unprecedented series of missions spanning many years, involving numerous nations and evolving from robotic to human exploration. Elements will be dispersed widely in longitude and latitude over the surface of Mars. Some surface elements like rovers, balloons and airplanes will be mobile. Other elements like sample canisters will orbit Mars. Finally manned sites

D. J. Bell; R. Cesarone; T. Ely; C. Edwards; S. Townes

2000-01-01

386

Dynamics of earth-orbiting flexible satellites with multibody components  

Microsoft Academic Search

A novel approach to the dynamics of satellites with flexible multibody components is proposed. The property of invariance under superposed rigid-body motions of geometrically-exact structural theories is employed to refer the dynamics of motion directly to the inertial frame. To avoid numerical ill conditioning, the dynamics of the far field and the near field are treated separately by introducing a

L. Vu-Quoc; J. C. Simof

1987-01-01

387

Composite Noise Temperature at Low Earth Orbiting Satellite Ground Station  

Microsoft Academic Search

Noise introduces a fundamental limit on the performance of any communication system. Satellite communication systems are particularly susceptible to noise because of their inherent low received power. During the link budget calculations, noises of the equipment and line loss have to be considered. An alternative, but equivalent way of expressing the noisiness of the equipment and line loss is through

Shkelzen Cakaj; Kresimir Malaric

2006-01-01

388

THE ORBITS AND MASSES OF THE MARTIAN SATELLITES AND THE LIBRATION OF PHOBOS  

SciTech Connect

This paper reports on an update to the orbits and masses of the Martian satellites Phobos and Deimos. We obtained the orbits by fitting a numerical integration to all available Earth-based astrometry through the opposition of 2003, spacecraft imaging observations through 2007, and the Doppler tracking of the Viking and Phobos 2 spacecraft; the Doppler data provide information on the satellite masses. Our dynamical model included the figure acceleration due to a librating Phobos; we determined the amplitude of the forced libration. We also took into account the secular acceleration of Phobos due to the tide that it raises on Mars and estimated the Martian tidal quality factor Q. We provide an assessment of the accuracy of the orbits and a geometrical description of the orbits in the form of mean elements.

Jacobson, R. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)], E-mail: robert.jacobson@jpl.nasa.gov

2010-02-15

389

Evolution of orbits and encounters of distant planetary satellites. Study tools and examples  

NASA Astrophysics Data System (ADS)

This study of the orbital evolution and encounters of distant satellites of planets is aimed at determining their origin. It is also important for understanding the distribution of matter in the early stages of evolution of the Solar System. The mutual encounter of satellites is very weak because of their small sizes and masses. However, at very large time intervals, mutual encounter can be quite close to significantly changing the orbits of satellites. In order to study these factors, we have developed a special method and computer programs. For 107 distant satellites of Jupiter, Saturn, Uranus, and Neptune, motion parameters have been determined using observational data. On the basis of these parameters, a numerical integration of the equations of motion of the satellites has been carried out in time intervals of several thousand years. Using the original method of frequency analysis, we found rather simple analytical functions that correspond to the results of the numerical integration and make it possible to calculate orbital parameters at any time during a long interval. These tools make it possible to conduct extensive studies of changes in the form and relative position in space of the orbits of distant satellites of Jupiter, Saturn, Uranus, and Neptune. Several examples illustrate the possibilities offered by these tools. The computer software in the form of a service ephemeris of satellite orbits over a long interval of time is available via the Internet (http://www.sai.msu.ru/neb/nss/evolu0e.htm) on the website of the State Astronomical Institute of the Moscow State University.

Emelyanov, N. V.; Vashkov'yak, M. A.

2012-11-01

390

The Orbits of the Neptunian Satellites and the Orientation of the Pole of Neptune  

NASA Astrophysics Data System (ADS)

Our previous ephemerides for the Neptunian satellites (Triton and Nereid) and our Neptune pole orientation were produced at the time of the Voyager Neptune encounter (Jacobson et al. 1991, A&A 247, 565). That work was done in the B1950 reference system. Since then we have amassed a quantity of high quality Earthbased observations of the satellites. We have also reconstructed the Voyager trajectory in the International Celestial Reference Frame (ICRF). This paper reports on an update to the satellite orbits and Neptune pole based on re-fitting all of the observations used previously together with those acquired through the opposition of 2007. We now include Proteus in our satellite system as it was used for an optical navigation target in the Voyager reconstruction. The new orbits and pole are referred to the ICRF. When processing the Voyager observations we use the new ICRF Voyager trajectory.

Jacobson, Robert A.

2008-05-01

391

Comparison and Accuracy Assessment of Semiempirical Atmosphere Models through the Orbital Decay of Spherical Satellites  

Microsoft Academic Search

,,,Abstract ,,,,,A detailed comparison,and,assessment ,of the ,accuracy ,of semi-empirical atmospheric ,density models (JR-71, MSIS-86\\/90, TD-88) was carried out, by analyzing the orbital decay of nine spherical,satellites in the ,150 - 1500 km altitude ,range. The orbital decay ,data ,used ,were distributed over a full solar activity cycle (1987-1999). The drag coefficients which were,estimated byfitting the observed semi-major axis evolution with

C. Pardini; L. Anselmo

392

In-orbit measurements of spacecraft microvibrations for satellite laser communication links  

Microsoft Academic Search

Angular microvibrations of platform jitter on the optical inter-orbit communications engineering test satellite are measured in space during ground-to-satellite laser communication links. The microaccelerations are measured by the onboard accelerometers at a sampling rate of 2048 Hz. The angular microvibrations are estimated from the measured microaccelerations using the tracking characteristics of the laser communications terminal and the conversion factor on

Morio Toyoshima; Yoshihisa Takayama; Hiroo Kunimori; Takashi Jono; Shiro Yamakawa

2010-01-01

393

Completion of Optical Inter-Orbit Communications Engineering Test Satellite (OICETS)  

Microsoft Academic Search

National Space Development Agency of Japan (NASDA) has developed the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) since 1993 in order to perform the optical inter-satellite communication experiment with ARTEMIS developed by European Space Agency (ESA). The system proto-fright test was completed in January 2002 and OICETS is ready for launch. OICETS has the free space laser communication equipment (so

K. Nakagawa; T. Yamawaki; M. Toyoshima; K. Arai

2002-01-01

394

Endogenic activity of medium size icy satellites of Saturn and eccentricities of their orbits  

Microsoft Academic Search

Global volcanic and tectonic activity observed on medium size icy satellites MIS of giant planets are probably a result of solid-state convection Tidal deformations and decay of radioactive elements are the main sources of heat in these bodies The tidal deformations depend on the eccentricity of the satellite s orbit The recent progress in 3D numerical modeling of solid-state convection

L. C. Czechowski

2006-01-01

395

Analytic design of satellite constellations for zonal earth coverage using inclined circular orbits  

NASA Astrophysics Data System (ADS)

The problem of identifying the minimum number of satellites in circular, inclined orbit constellations at the same altitude which provide continuous, single, and redundant coverage for global, polar cap, equatorial, and zonal areas of the earth's surface is solved analytically in closed form using street-of-coverage techniques with arbitrary interorbit plane phasing of satellites. The results are compared with optimal polar constellations and optimal inclined constellations as defined by Walker (1977) for single, double, triple, and quadruple coverage requirements.

Rider, L.

1986-03-01

396

Approximate analysis for relative motion of satellite formation flying in elliptical orbits  

Microsoft Academic Search

This paper studies the relative motion of satellite formation flying in arbitrary elliptical orbits with no perturbation.\\u000a The trajectories of the leader and follower satellites are projected onto the celestial sphere. These two projections and\\u000a celestial equator intersect each other to form a spherical triangle, in which the vertex angles and arc-distances are used\\u000a to describe the relative motion equations.

Fanghua Jiang; Junfeng Li; Hexi Baoyin

2007-01-01

397

Impact of GPS antenna phase center variations on precise orbits of the GOCE satellite  

NASA Astrophysics Data System (ADS)

The first European Space Agency Earth explorer core mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) has been launched on March 17, 2009. The 12-channel dual-frequency Global Positioning System receiver delivers 1 Hz data and provides the basis for precise orbit determination (POD) on the few cm-level for such a very low orbiting satellite (254.9 km). As a member of the European GOCE Gravity Consortium, which is responsible for the GOCE High-level Processing Facility (HPF), the Astronomical Institute of the University of Bern (AIUB) provides the Precise Science Orbit (PSO) product for the GOCE satellite. The mission requirement for 1-dimensional POD accuracy is 2 cm. The use of in-flight determined antenna phase center variations (PCVs) is necessary to meet this requirement. The PCVs are determined from 154 days of data and the magnitude is up to 3-4 cm. The impact of the PCVs on the orbit determination is significant. The cross-track direction benefits most of the PCVs. The improvement is clearly seen in the orbit overlap analysis and in the validation with independent Satellite Laser Ranging (SLR) measurements. It is the first time that SLR could validate the cross-track component of a LEO orbit.

Bock, H.; Jäggi, A.; Meyer, U.; Dach, R.; Beutler, G.

2011-06-01

398

Digital transmission experiments with the Orbital Test Satellite  

NASA Astrophysics Data System (ADS)

Digital satellite communication experiments in the 11/14 GHz band were performed on a 115 km link by OTS (ESA). Equipment was developed and tested via a translator loop. For transmission and reception of RF signals, paraboloid antennas of 3 and 8 m diameter were used. Digital transmission tests were carried out via the OTS-A and OTS-B transponders. Spectra of the transmitted and received signals were measured for different QPSK modulation and demodulation strategies at bit rates of 4 and 8.448 Mbit/sec. Videophone and single channel per carrier digital telephony demonstrations in satellite loop operation were given. Bit error rate was measured for QPSK modulation at bitrates of 4 and 8.448 and 32 kbit/sec.

Dijk, J.; Verlijsdonk, A. P.; Arnbak, J. C.

1984-10-01

399

Regenerative fuel cell study for satellites in GEO orbit  

Microsoft Academic Search

Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr\\/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the

Alexander Levy; Leslie L. Vandine; James K. Stedman

1987-01-01

400

Technical and economic feasibility of telerobotic on-orbit satellite servicing  

NASA Astrophysics Data System (ADS)

The aim of this research is to devise an improved method for evaluating the technical and economic feasibility of telerobotic on-orbit satellite servicing scenarios. Past, present, and future telerobotic on-orbit servicing systems and their key capabilities are examined. Previous technical and economic analyses of satellite servicing are reviewed and evaluated. The standard method employed by previous feasibility studies is extended, developing a new servicing decision approach incorporating operational uncertainties (launch, docking, et cetera). Comprehensive databases of satellite characteristics and on-orbit failures are developed to provide input to the expected value evaluation of the servicing versus no-servicing decision. Past satellite failures are reviewed and analyzed, including the economic impact of those satellite failures. Opportunities for spacecraft life extension are also determined. Servicing markets of various types are identified and detailed using the results of the database analysis and the new, expected-value-based servicing feasibility method. This expected value market assessment provides a standard basis for satellite servicing decision-making for any proposed servicing architecture. Finally, the method is demonstrated by evaluating a proposed small, lightweight servicer providing retirement services for geosynchronous spacecraft. An additional benefit of the method is that it enables parametric analysis of the sensitivity of economic viability to the probability of docking success, thus establishing a threshold for that critical value. While based on a more economically conservative approach, the new method demonstrates the feasibility of the proposed server in the face of operational uncertainties.

Sullivan, Brook Rowland

401

Orbit determination for a low-drag satellite with sparse observations  

NASA Astrophysics Data System (ADS)

The RAE orbit refinement program PROP has been used to determine the orbit of a low-drag satellite, 1971-110C, from 45 visual observations over 18 months between 30 June 1984 and 31 December 1985. The orbit is circular at a height of 100 km, and the inclination to the equator is 70 deg. With the aid of the related program PREP, predictions were made for April 1986 which proved to be in error by 12 seconds in time, and predictions have been provided for August and December 1986.

King-Hele, D. G.

1986-06-01

402

a Permanent Magnet Hall Thruster for Orbit Control of Lunar Polar Satellites  

NASA Astrophysics Data System (ADS)

Future moon missions devoted to lunar surface remote sensing and to many others scientific exploration topics will require more fine and higher precision 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 life time 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. In the present work, we propose a precise method of orbit eccentricity control based on the use of a low thrust Hall plasma thruster. The proposed method is based on an approach intended to keep the orbital eccentricity of the satellite at low values. A previous work on this subject was made using numerical integration considering two systems: the 3-body problem, Moon-Earth-satellite and the 4-body problem, Moon-Earth-Sun-satellite (??). In such simulation it is possible to follow the evolution of the satellite's eccentricity and find empirical expressions for the length of time needed to occur the collision with the moon. In this work, a satellite orbit eccentricity control maneuvering is proposed. It is based on working parameters of a low thrust propulsion permanent magnet Hall plasma thruster (PMHT), which is been developed at University of Brasilia, Brazil. We studied different arcs of active lunar satellite propulsion in order to be able to introduce a correction of the eccentricity at each cycle. The calculations were made considering a set of different thrust values, from 0.1N up to 0.4N which can be obtained by using the PMHT. In each calculation procedure we measured the length of eccentricity correction provided by active propulsion. From these results we obtained empirical expressions of the time needed for the corrections as a function of the initial altitude and as a function of the thrust value. 1. Winter, O. C. et all in Controlling the Eccentricity of Polar Lunar Orbits with Low Thrust Propulsion, Mathematical Problems in Engineering, vol. on Space Dynamics, 2009.

Ferreira, Jose Leonardo; Silva Moraes, Bruno; Soares Ferreira, Ivan; Cardozo Mour, Decio; Winter, Othon

403

Comparison of low-Earth-orbit satellite attitude controllers submitted to controllability constraints  

NASA Astrophysics Data System (ADS)

A rule-based fuzzy controller is presented and compared with an adaptive MIMO LQR controller in a low-earth-orbit small satellite attitude control system. The attitude is passively gravity gradient stabilized and actively three-axis magnetorquer controlled. This method insures an earth-pointing satellite making use of a nondepletable and nonmechanical means of control. A realistic simulation environment, using a nonlinear satellite dynamic model with linear attitude estimators plus sensor measurement noise and external disturbance torques, was used to evaluate the different control techniques.

Steyn, Willem H.

1994-07-01

404

Non-conservative GNSS satellite modeling: long-term orbit behavior  

NASA Astrophysics Data System (ADS)

Modeling of non-conservative forces is a key issue for precise orbit determination of GNSS satellites. Furthermore, mismodeling of these forces has the potential to explain orbit-related frequencies found in GPS-derived station coordinates and geocenter, as well as the observed bias in the SLR-GPS residuals. Due to the complexity of the non-conservative forces, usually they have been compensated by empirical models based on the real in-orbit behavior of the satellites. Recent studies have focused on the physical/analytical modeling of solar radiation pressure, Earth radiation pressure, thermal effects, antenna thrust, among different effects. However, it has been demonstrated that pure physical models fail to predict the real orbit behavior with sufficient accuracy. In this study we use a recently developed solar radiation pressure model based on the physical interaction between solar radiation and satellite, but also capable of fitting the GNSS tracking data, called adjustable box-wing model. Furthermore, Earth radiation pressure and antenna thrust are included as a priori acceleration. The adjustable parameters of the box-wing model are surface optical properties, the so-called Y-bias and a parameter capable of compensating for non-nominal orientation of the solar panels. Using the adjustable box-wing model a multi-year GPS/GLONASS solution has been computed, using a processing scheme derived from CODE (Center for Orbit Determination in Europe). This multi-year solution allows studying the long-term behavior of satellite orbits, box-wing parameters and geodetic parameters like station coordinates and geocenter. Moreover, the accuracy of GNSS orbits is assessed by using SLR data. This evaluation also allows testing, whether the current SLR-GPS bias could be further reduced.

Rodriguez-Solano, C. J.; Hugentobler, U.; Steigenberger, P.; Sosnica, K.; Fritsche, M.

2012-04-01

405

Satellite Formation Flying for Geodetic Applications: Analysis of J2-Disturbed Orbits  

NASA Astrophysics Data System (ADS)

Future geodetic satellite missions will most probably make use of the concepts of satellite formation flying. Most studies use Hill equations (HE) to describe the relative motion of the chief satellite and deputy satellite. Some underlying assumptions limit the applicability of HE: (1) the Earth is spherically symmetric; (2) the orbit of the Hill frame is rigorously a circle; (3) the relative distance between the satellites is small compared with the radius of the Earth. Under these assumptions, the homogeneous solutions of HE describe relative orbit motion very well. In reality, the situation is much more complicated. The second zonal spherical harmonic of the Earth,J2,produces the primary gravitational perturbations. This J2 force includes secular, long-periodic, and short-periodic components, which consequently will perturb the satellite orbits. Our objective in this presentation is to study the relative motion between arbitrary chief and deputy satellite configurations due to J2 disturbance for geodetic applications. Four different methods, (1) numerical integration of Newton equations; (2) numerical integration of Lagrange Planetary Equations (LPE) in Gauss form, (3) numerical integration of HE; and (4) nontrivial analytical solutions of HE, will be used to analyze the relative motions in the Hill rotating frame. Since this J2 perturbation has a two cycle per revolution (CPR) frequency component, we developed a complementary analytical solutions for the non-homogeneous HE, which combine the homogeneous, resonant and non-resonant solution. Our preliminary results show that numerical integration of Newton equations and LPE can capture all disturbance characteristics, while the numerical or analytical method of HE perform relatively well in the differential mode. Furthermore, one can get any designed shapes of the relative motion by setting specific initial positions and velocities, e.g. 2 by 1 elliptic motion in the orbital plane.

Xu, C.; Tsoi, R.; Sneeuw, N.

2004-05-01

406

Simulating Realistic Satellite Orbits in the Undergraduate Classroom  

NASA Astrophysics Data System (ADS)

Physics students are intrigued by activities in space. To link this natural curiosity with solid problem-solving skills, we developed a spreadsheet simulation for satellites moving through an atmosphere of variable density. The simulation-laboratory has been used in U.S. Air Force Academy (USAFA) introductory physics classes for several semesters. Spreadsheet variants have also been used in a USAFA advanced division space physics class, a high school advanced placement physics class, and in the Center for Integrated Space Weather Modeling graduate summer school course.

Knipp, D. J.; Patterson, E. T.; Franz, A.; Head, J. H.; Summers, T. A.; Zirbel, E. L.

2005-10-01

407

The constitution and characteristics of 20 GHz band high power transmitter for communications satellite  

Microsoft Academic Search

The paper describes the design and characteristics of two 20 GHz band high-power transmitters onboard a communication satellite. The type A transmitter is a lightweight model noted for its electrical performance, while the type B transmitter is an environmental test model designed to withstand severe launching and geostationary orbit conditions. Both transmitters consist of active and standby TWT amplifiers, single

M. Nakamura; F. Kawashima; A. Iso

1975-01-01

408

Optimization of microwave power transmission from solar power satellites. Ph.D. Thesis  

Microsoft Academic Search

Solar energy can be used to avoid environmental problems associated with the use of fossil fuels. Because of limitations on the availability of solar energy at the Earth`s surface, it is recommended that energy from the sun be harnessed by solar collectors in geostationary orbit, known as solar power satellites (SPS). The energy collected is transmitted to the Earth by

1993-01-01

409

Explaining why the uranian satellites have equatorial prograde orbits despite the large planetary obliquity  

NASA Astrophysics Data System (ADS)

We show that the existence of prograde equatorial satellites is consistent with a collisional tilting scenario for Uranus. In fact, if the planet was surrounded by a proto-satellite disk at the time of the tilting and a massive ring of material was temporarily placed inside the Roche radius of the planet by the collision, the proto-satellite disk would have started to precess incoherently around the equator of the planet, up to a distance greater than that of Oberon. Collisional damping would then have collapsed it into a thin equatorial disk, from which the satellites eventually formed. The fact that the orbits of the satellites are prograde requires Uranus to have had a non-negligible initial obliquity (comparable to that of Neptune) before it was finally tilted to 98°.

Morbidelli, A.; Tsiganis, K.; Batygin, K.; Crida, A.; Gomes, R.

2012-06-01

410

Multi-satellite rainfall sampling error estimates - a comparative study  

NASA Astrophysics Data System (ADS)

This study focus is set on quantifying sampling related uncertainty in the satellite rainfall estimates. We conduct observing system simulation experiment to estimate sampling error for various constellations of Low-Earth orbiting and geostationary satellites. There are two types of microwave instruments currently available: cross track sounders and conical scanners. We evaluate the differences in sampling uncertainty for various satellite constellations that carry instruments of the common type as well as in combination with geostationary observations. A precise orbital model is used to simulate realistic satellite overpasses with orbital shifts taken into account. With this model we resampled rain gauge timeseries to simulate satellites rainfall estimates free of retrieval and calibration errors. We concentrate on two regions, Germany and Benin, areas with different precipitation regimes. Our results show that sampling uncertainty for all satellite constellations does not differ greatly depending on the area despite the differences in local precipitation patterns. Addition of 3 hourly geostationary observations provides equal performance improvement in Germany and Benin, reducing rainfall undersampling by 20-25% of the total rainfall amount. Authors do not find a significant difference in rainfall sampling between conical imager and cross-track sounders.

Itkin, M.; Loew, A.

2012-10-01

411

Estimating the Effect of Satellite Orbital Error Using Wavelet-Based Robust Regression Applied to InSAR Deformation Data  

Microsoft Academic Search

Interferometric synthetic aperture radar data are of- ten obtained on the basis of repeated satellite acquisitions. Errors in the satellite orbit determination, however, propagate to the data analysis and may even entirely obscure the interpretation. Many approaches have been developed to correct the effect of orbital error, which sometimes may even distort the signal. Phase contributions due to other sources,

Manoochehr Shirzaei; Thomas R. Walter

2011-01-01

412

The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS): A Potential Canadian Mission Contribution to ILWS  

Microsoft Academic Search

The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission is presently undergoing Concept Study as a Canadian Space Agency satellite mission contribution to ILWS. The ORBITALS will provide a unique view of the largely previously unexplored inner magnetosphere. Its mission goal to \\

I. R. Mann; D. K. Milling; R. Rankin; R. Fedosejevs; Y. Y. Tsui; D. Knudsen; A. W. Yau; J. R. Wygant; J. F. Fennel; J. B. Blake; T. P. O'Brien; J. H. Clemmons; D. Summers; G. Sofko; D. Boteler

2004-01-01

413

Effects of gravity-gradient torque on the rotational motion of A triaxial satellite in a precessing elliptic orbit  

Microsoft Academic Search

A method of general perturbations, based on the use of Lie series to generate approximate canonical transformations, is applied to study the effects of gravity-gradient torque on the rotational motion of a triaxial, rigid satellite. The center of mass of the satellite is constrained to move in an elliptic orbit about an attracting point mass. The orbit, which has a

John E. Cochran

1972-01-01

414

Combined processing and orbit determination of Galileo and GPS satellites by estimating phase clocks  

Microsoft Academic Search

As a first step we introduced Galileo observables in the Bernese GPS software to study the combined processing of Galileo and GPS measurements based on the estimation of phase clocks for both GNSS systems We then simulated measurements for both the Galileo and the GPS constellation and estimated all relevant IGS parameters like Galileo GPS orbits high-rate Galileo GPS satellite

D. Svehla

2006-01-01

415

A Pegasus Computer Programme for the Assessment of the Accuracy of Satellite Orbit Determination.  

National Technical Information Service (NTIS)

A computer programme is described by means of which one may estimate the potential accuracy of the elements of a given satellite orbit, if determined from observational data of specified type and assumed accuracy. An application of the programme is made t...

R. H. Gooding

1965-01-01

416

Explicit forms of some functions arising in the analysis of resonant satellite orbits  

Microsoft Academic Search

The analysis of resonant satellite orbits has been pursued for 18 years, and has led to the most accurate values available for lumped geopotential harmonics of the relevant orders. The basic theory for the resonance effects was developed in the 1960s, but the detailed application of the technique calls for a systematic notation and for the evaluation of two subsidiary

R. H. Gooding; D. G. King-Hele

1988-01-01

417

Analysis of the Relative Attitude Estimation and Control Problem for Satellite Inspection and Orbital Rendezvous  

Microsoft Academic Search

A key component of satellite inspection and orbital rendezvous missions is relative atti- tude estimation and control. This paper analyzes a specific angles-only relative attitude estimation concept where it is assumed that a chaser spacecraft is capable of processing onboard imagery of a resident space object (RSO) and identifying the pixel locations of pre- selected RSO features. The pixel measurements

D. Geller

418

Explicit forms of some functions arising in the analysis of resonant satellite orbits  

Microsoft Academic Search

The analysis of resonant satellite orbits has been pursued for 18 years, and has led to the most accurate values available for lumped geopotential harmonics of the relevant orders. The basic theory for the resonance effects was developed in the 1960s, but the detailed application of the technique calls for a systematic notation and for the evaluation of two subsidiary

R. H. Gooding; D. G. King-Hele

1989-01-01

419

Electrostatic Discharge Ground Test of a Polar Orbit Satellite Solar Panel  

Microsoft Academic Search

The Advanced Land Observing Satellite that was launched by the Japan Aerospace Exploration Agency in 2006 carries a large solar-array paddle of 22 times 3 m in polar orbit. The wake side of the solar paddle can be charged to a negative value exceeding -1000 V. Numerical simulations and laboratory experiments are carried out to investigate charging and arcing phenomena

Mengu Cho; Jeong-ho Kim; Satoshi Hosoda; Yukishige Nozaki; Takeshi Miura; Takanori Iwata

2006-01-01

420

Applications in Military Communications of Low and Medium Earth Orbit Commercial Satellite Systems.  

National Technical Information Service (NTIS)

At the dawn of the 21st century several Low and Medium Earth Orbit Commercial Satellite constellations will be operational and they will be able to provide high bandwidth Global Communications in voice, data and multimedia services for mobile consumers an...

I. Kakavas

1997-01-01

421

Forecasting the impact of an 1859-caliber superstorm on geosynchronous Earth-orbiting satellites: Transponder resources  

Microsoft Academic Search

We calculate the economic impact on the existing geosynchronous Earth-orbiting satellite population of an 1859-caliber superstorm event were it to occur between 2008 and 2018 during the next solar activity cycle. From a detailed model for transponder capacity and leasing, we have investigated the total revenue loss over the entire solar cycle, as a function of superstorm onset year and

Sten F. Odenwald; James L. Green

2007-01-01

422

A Correction Method of Orbit Elements Using Amateur Radio Facilities for Nano-Satellites  

Microsoft Academic Search

A correction method of orbit elements for nano-satellites using simple and low cost facilities is required. In this study, the Doppler shift of the beacon signal from a cubesat was observed using an amateur radio. The history of frequency variation was recorded for different TLEs with different epoch time. The frequency difference translated into seconds (FDTS) was deduced as a

Yasuhisa Oda; Shinichi Nakasuka; Priya Fernando

2008-01-01

423

Motion Estimation to a Failed Satellite on Orbit using Stereo Vision and 3D Model Matching  

Microsoft Academic Search

An algorithm is developed for estimating the motion (relative attitude and relative position) of large pieces of space debris, such as failed satellites. The algorithm is designed to be used by a debris removal system which would perform various operations on space debris such as observation, investigation, capture, repair, refuel and de-orbit. During these operations, the debris removal system must

Fuyuhito Terui; Heihachiro Kamimura; Shin-ichiro Nishida

2006-01-01

424

Measurement of Primary and Albedo Cosmic Rays on a Polar Orbiting Satellite.  

National Technical Information Service (NTIS)

Relative contributions of primary cosmic ray, splash albedo and re-entrant albedo fluxes were evaluated from the altitude dependence of a triple coincidence counter telescope on board the satellite Discoverer 29 in a polar orbit in 1961. The results are: ...

T. Murayama

1967-01-01

425

Measurement of atmospheric ultraviolet radiation from a low-Earth orbit satellite  

Microsoft Academic Search

The design and expected measurements of the atmospheric ultraviolet radiance analyzer (AURA), a satellite experiment, are presented. The goal of AURA is to provide global measurements of the ultraviolet emissions (1150 angstrom to 1900 angstrom) from the Earth's atmosphere. These measurements will include spectra and images. AURA is expected to fly in a near circular, high inclination angle orbit. AURA

Steve Clegg; Richard W. Eastes; Michael E. Gangl; John H. Middlestadt

1994-01-01

426

Metop-B, the second satellite of the EUMETSAT Polar System, in orbit  

NASA Astrophysics Data System (ADS)

The EUMETSAT Polar System is EUMETSAT's contribution to the Global Meteorological Satellite Observing System in the polar sun-synchronous orbit and serves, in the frame of the Initial Joint Polar System (IJPS) with the United States, the mid-morning orbit. The space segment is composed of the Metop satellites, of which Metop-A is in orbit since 2006, providing a wealth of Earth Observation data, amongst them data for Atmospheric Sounding, cloud and surface monitoring, ocean observation, including ocean winds, atmospheric composition monitoring. The launch of Metop-B on the 17 September 2013 into the same mid-morning orbit (9:30 LST equator crossing time, descending node, phased 48 min. apart from Metop-A) at 820 km assures the continuity of the system. A third Metop satellite (Metop-C), scheduled for launch early 2018, will assure mission duration of at least 15 years. This paper discusses the status of the EUMETSAT Polar System (EPS) and in particular presents the results from Metop-B commissioning and the actual status of products. Metop-B is out of its commissioning at the time of the conference and is providing its service as the prime satellite together with Metop-A, which is healthy and continues its successful service.

Klaes, K. Dieter; Montagner, Francois; Larigauderie, Carole

2013-09-01

427

Variable attitude maneuver through tether for a ‘drifting’ twin satellite system in elliptic orbits  

Microsoft Academic Search

A twin satellite system comprising of two spacecraft halves connected through four, very short tethers has been considered for specific communication application in high altitude elliptic orbits. The tether tension moments based on the open-loop control law developed analytically facilitate simultaneous handling of the twin problems: longitudinal system drift relative to the ground station as well as attitude excitation induced

Krishna Kumar

1999-01-01

428

Orbit/Launch Vehicle Tradeoff Studies. Earth Observatory Satellite System Definition Study (Eos).  

National Technical Information Service (NTIS)

An evaluation of the Earth Observatory Satellite (EOS) design, performance, and cost factors which affect the choices of an orbit and a launch vehicle is presented. Primary emphasis is given to low altitude (300 to 900 nautical miles) land resources manag...

1974-01-01

429

Prospects for geostationary doppler weather radar  

Microsoft Academic Search

A novel mission concept, namely NEXRAD in Space (NIS), was developed for detailed monitoring of hurricanes, cyclones, and severe storms from a geostationary orbit. This mission concept requires a space deployable 35-m diameter reflector that operates at 35-GHz with a surface figure accuracy requirement of 0.21 mm RMS. This reflector is well beyond the current state-of-the-art. To implement this mission

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

2009-01-01

430

Application of multi-source data fusion in navigation satellite autonomous orbit determination  

NASA Astrophysics Data System (ADS)

Aiming at the orbit floating or so called constellation rotation in navigation satellite autonomous orbit determination, an approach based on multi sources data fusion was introduced, that is to introduce angle observation from on board star sensor toward fixed star to fix the ascending node ?, one of the six orbit elements so as to avoid constellation rotation. During data processing, a generalized measurement model based on matrix Cholesky decomposition and the method of measurement noises de-correlation was adopted. On the foundation of roundly analysis of present theories and methods of multi sources data fusion, and characteristics of multi sources measurement data fusion taken into account, two sorts of multi sources data fusion measurement models based on independent same distribution and correlation of measurement noises were conducted. Theoretical analysis and simulation experiment show that navigation satellite autonomous orbit determination based on multi sources data fusion can well solve the problem of orbit floating contrasting against that of only inter-satellite observations used.

Hou, Fen; Liu, Hui

2009-10-01

431

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

NASA Astrophysics Data System (ADS)

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

Cai, Chenglin; Li, Xiaohui; Wu, Haitao

2010-12-01

432

The Contribution Of The Oblateness Of An Asteroid On The Orbital Evolution Of Its Satellites  

NASA Astrophysics Data System (ADS)

About five years ago was discovered the first asteroid to have a pair of small satellites. That was 87 Sylvia with its satellites Romulus and Remus (Marchis et al. 2005). Nowadays a few more cases are known. A preliminary study of the long term dynamics of Romulus and Remus (Winter et al. 2009) showed that their trajectories would be highly unstable if Sylvia had a symmetrically spherical gravitational potential. However, Sylvia is highly oblate, J2=0.17. Consequently, the inclusion of J2 in the dynamics results in very stable trajectories for Romulus and Remus. That is mainly due to the fact that the orbital angular momenta of the satellites increase significantly due to J2. In the present work we show the results of a study of the evolution of the spin axis of the main asteroid and its effects on the orbital motion of the small satellites. In the dynamics of the spin is taken into account the perturbation of the Sun and Jupiter. The orbital planes of the satellites follow the equatorial plane of the asteroid. Acknowledgements: This work has the support of FAPESP, CNPq and CAPES

Cabo Winter, Othon; Boldrin, L. G.; Vieira Neto, E.; Gomes, R.

2010-10-01

433

Artificial satellites orbits in 2:1 resonance: GPS constellation  

NASA Astrophysics Data System (ADS)

In this work, the resonance problem in the artificial satellites motion is studied. The development of the geopotential includes the zonal harmonics J20 and J40 and the tesseral harmonics J22 and J42. Through an averaging procedure and successive Mathieu transformations, the order of dynamical system is reduced and the final system is solved by numerical integration. In the simplified dynamical model, three critical angles are studied. The half-width of the separatrix is calculated through a linearized model which describes the behavior of the dynamical system in a neighborhood of each critical angle. Through the resonance overlap criterion the possible regular and irregular motions are investigated by the time behavior of the semi-major axis, argument of perigee and eccentricity. The largest Lyapunov exponent is used as tool to verify the chaotic motion.

Sampaio, J. C.; Neto, A. G. S.; Fernandes, S. S.; Vilhena de Moraes, R.; Terra, M. O.

2012-12-01

434

Fault tolerant computer for low Earth orbit micro satellites  

NASA Astrophysics Data System (ADS)

This paper describes the design of the On Board Computer of Singapore's X-Sat micro satellite. The architecture incorporates the philosophies of modularity and scalability. It is based around a reliable processing core made of at least one FPGA and one microprocessor. The rest of the hardware is grouped together into functional banks using redundancy in banks for higher reliability. After the first version of the platform is validated, development effort for future missions would be substantially reduced. The computer can be reconfigured to adapt to varying mission needs, thus building a heritage with the system. The FPGA in the processing core enables transparent interfacing between heterogeneous device types when required. This combined with the modular nature of the design provides for easy upgradeability to viable technologies that become available over time. This also provides a useful platform to test out emerging devices and device types.

Mohan, D.; Arichandran, K.; McLoughlin, I.

2004-11-01

435

Space-based augmentation for global navigation satellite systems.  

PubMed

This paper describes space-based augmentation for global navigation satellite systems (GNSS). Space-based augmentations increase the accuracy and integrity of the GNSS, thereby enhancing users' safety. The corrections for ephemeris, ionospheric delay, and clocks are calculated from reference station measurements of GNSS data in wide-area master stations and broadcast via geostationary earth orbit (GEO) satellites. This paper discusses the clock models, satellite orbit determination, ionospheric delay estimation, multipath mitigation, and GEO uplink subsystem (GUS) as used in the Wide Area Augmentation System developed by the FAA. PMID:22481784

Grewal, Mohinder S

2012-03-01

436

New improved orbit solutions for the ERS-1 and ERS-2 satellites  

NASA Astrophysics Data System (ADS)

Improved orbit solutions of the European Remote Sensing Satellites ERS-1 and ERS-2 have been computed in the ITRF2005 terrestrial reference frame using the recent models based mainly on IERS Conventions 2003. These solutions cover the periods 3 August 1991 to 8 July 1996 for ERS-1, and 3 May 1995 to 4 July 2003 for ERS-2. For each satellite, the final orbit solution is based on a combination of three separate orbit solutions independently computed at the Delft Institute of Earth Observation and Space Systems (DEOS) of the Delft University of Technology (The Netherlands), the Navigation Support Office of the European Space Operations Centre (ESOC, Germany) and the Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences (Germany) using three different software packages for precise orbit determination, but using the same models in the same terrestrial reference frame within the European Space Agency (ESA) project 'Reprocessing of Altimeter Products for ERS (REAPER)'. Validation using radar altimeter data indicates that the new combined orbits of ERS-1 and ERS-2 computed by us are significantly more accurate, approaching the 2-3 cm level in radial direction, than previously available orbit solutions.

Rudenko, Sergei; Otten, Michiel; Visser, Pieter; Scharroo, Remko; Schöne, Tilo; Esselborn, Saskia

2012-04-01

437

Long-periodic and secular perturbations to the orbit of a spherical satellite due to direct solar radiation pressure  

Microsoft Academic Search

A theory is developed for the perturbations to the orbit of a spherically symmetric satellite which accounts for the changes in the perigee and nodal positions and the variations of the Sun-Earth distance and direction over an orbital revolution. The theory is semi-analytical, the equations of motion being integrated with respect to time over the sunlit period of each orbital

N. M. Harwood; G. G. Swinerd

1995-01-01

438

Satellite orbits, their observables, and tests of gravity theories  

NASA Astrophysics Data System (ADS)

Spectrometric detector complex ZINA-NT is intended to study a radiation conditions onboard satellite and characteristics of hard X-ray and gamma-ray fluxes from GRB, solar flares and to detect other non-stationary fluxes of cosmic gamma-rays. The advantages for using of this new detector for modification of present neutral particles detector on base of CsI(Tl) are discussed. Scintillation detectors based on BrilLanCe series crystal has a very small lighting time, an excellent energy resolution and light output, more intensive than devices based on CsI(Tl). Using of BrilLanCe series crystal instead of CsI(Tl) ones allows to detect both terrestrial gamma flashes and solar gamma ray bursts and flares with smaller time durations and intensities. Moreover, the counts rate linearity region of BrilLanCe detectors is extended up to 106 s-1 and it allows to observe a very intensive events. So, the using of such type of detector permits us the possibility to separate gamma-quanta and neutrons on the timescales less than 50 microseconds.

Laemmerzahl, Claus; Perlick, Volker

439

Improving the orbits of GPS block IIA satellites during eclipse seasons  

NASA Astrophysics Data System (ADS)

During Sun-Earth eclipse seasons, GPS-IIA satellites perform noon, shadow and post-shadow yaw maneuvers. If the yaw maneuvers are not properly taken into account in the orbit determination process, two problems appear: (1) the observati