These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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.

2

On orbital allotments for geostationary satellites  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

3

Servicing communication satellites in geostationary orbit  

NASA Technical Reports Server (NTRS)

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

Russell, Paul K.; Price, Kent M.

1990-01-01

4

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

Code of Federal Regulations, 2014 CFR

...in-line interference events for Non Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the Fixed-Satellite...in-line interference events for Non Geostationary Satellite Orbit (NGSO) Satellite Network Operations in the...

2014-10-01

5

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

6

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

7

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

E-print Network

N OAA's geostationary and polar-orbiting satellites provide critical data for short-term and long understanding of the Earth. Our satellites also monitor environmental concerns, such as severe weather events for Better Forecasts NOAA operates two types of satellites that provide real-time imagery daily

8

47 CFR 25.146 - Licensing and operating rules for the non-geostationary orbit Fixed-Satellite Service in the 10.7...  

Code of Federal Regulations, 2014 CFR

...operating rules for the non-geostationary orbit Fixed-Satellite Service in the 10.7...operating rules for the non-geostationary orbit Fixed-Satellite Service in the 10.7...the proposed non-geostationary satellite orbit Fixed-Satellite Service (NGSO...

2014-10-01

9

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

10

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

11

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

12

EUROPE'S GEOSTATIONARY METEOROLOGICAL SATELLITES  

E-print Network

METEOSAT EUROPE'S GEOSTATIONARY METEOROLOGICAL SATELLITES MONITORING WEATHER AND CLIMATE FROM SPACE, 6 July 2010 Paul de Valk Koninklijk nederlands Meteorologisch instituut (KnMi) "you need satellites for a country to have its own satellites so it is very beneficial to share costs in Europe, as we do through Eu

Stoffelen, Ad

13

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

14

Land and Ocean Surface Skin Temperature from Geostationary and Low Earth Orbit Satellite Observations  

NASA Astrophysics Data System (ADS)

Observations from imagers aboard Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO) satellites allow for spatially detailed, near-real-time retrievals of cloud and surface radiation properties. Validating and improving the quality of these observations is important for the advancement of climate studies. Compared to GEO sensors, LEO-based instruments can typically provide higher-spatial-resolution datasets, but at the cost of limited areal coverage and reduced sampling frequency at any given location. Conversely, the persistence and coverage of GEO-based imagers offer the opportunity for more frequent retrievals of near-instantaneous, near-global surface properties. Among other cloud and clear-sky retrieval parameters, NASA Langley provides pixel-level land and ocean skin temperature datasets by comparing clear-pixel top-of-atmosphere infrared temperature observations with modeled, atmospheric-absorption-corrected surface temperature values. Depending on cloud-cover thresholds, this method yields surface temperature values that are within 0.5 to 2.0 K of measurements from ground-based networks including the Southern Great Plains Atmospheric Radiation Measurement Climate Research Facility, the U.S. Climate Reference Network, and the global Baseline Surface Radiation Network. Furthermore, monthly mean sea surface temperatures (SSTs) are within 0.5 to 2.0 K of NOAA-based SST climatology records, and have an uncertainty of less than 1 K. These data will be useful for assimilation into atmospheric models, which offer improved performance when high-accuracy, high-resolution initial radiometric and surface conditions are included. Modelers should find the immediate availability and broad coverage of these skin temperature observations valuable, which can lead to improved forecasting and more advanced global climate models.

Scarino, B. R.; Minnis, P.; Palikonda, R.; Heck, P.; Bedka, K.

2013-12-01

15

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

16

Analysis of geostationary orbital slot availability for the SPS programme  

NASA Astrophysics Data System (ADS)

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

Flower, R. J.

17

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

18

Transmitter diversity verification on ARTEMIS geostationary satellite  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

19

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-03-29

20

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2011 CFR

...Interference to geostationary-satellites. 78.106 Section 78...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12776,...

2011-10-01

21

47 CFR 101.145 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2011 CFR

...Interference to geostationary-satellites. 101.145 Section 101...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. These limitations...geostationary-space stations in the fixed-satellite service. (a)...

2011-10-01

22

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2011 CFR

...Interference to geostationary-satellites. 74.643 Section 74...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12771,...

2011-10-01

23

47 CFR 101.145 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2012 CFR

...Interference to geostationary-satellites. 101.145 Section 101...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Link to an amendment...geostationary-space stations in the fixed-satellite service. (a)...

2012-10-01

24

47 CFR 101.145 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2010 CFR

...Interference to geostationary-satellites. 101.145 Section 101...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. These limitations...geostationary-space stations in the fixed-satellite service. (a)...

2010-10-01

25

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2012 CFR

...Interference to geostationary-satellites. 74.643 Section 74...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12771,...

2012-10-01

26

47 CFR 101.145 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2013 CFR

...Interference to geostationary-satellites. 101.145 Section 101...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. These limitations...geostationary-space stations in the fixed-satellite service. (a)...

2013-10-01

27

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2012 CFR

...Interference to geostationary-satellites. 78.106 Section 78...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12776,...

2012-10-01

28

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2013 CFR

...Interference to geostationary-satellites. 74.643 Section 74...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12771,...

2013-10-01

29

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2010 CFR

...Interference to geostationary-satellites. 78.106 Section 78...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12776,...

2010-10-01

30

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2010 CFR

...Interference to geostationary-satellites. 74.643 Section 74...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12771,...

2010-10-01

31

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2013 CFR

...Interference to geostationary-satellites. 78.106 Section 78...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12776,...

2013-10-01

32

47 CFR 78.106 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2014 CFR

...Interference to geostationary-satellites. 78.106 Section 78...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12776,...

2014-10-01

33

47 CFR 74.643 - Interference to geostationary-satellites.  

Code of Federal Regulations, 2014 CFR

...Interference to geostationary-satellites. 74.643 Section 74...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Interference to geostationary-satellites. Applicants and licensees...interference to geostationary-satellites. [68 FR 12771,...

2014-10-01

34

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

35

Geostationary satellite observations of dynamic phytoplankton photophysiology  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

36

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

Code of Federal Regulations, 2013 CFR

...Network Operations in the Fixed-Satellite Service (FSS) Bands. 25...261 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards §...

2013-10-01

37

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

Code of Federal Regulations, 2010 CFR

...Network Operations in the Fixed Satellite Service (FSS) Bands. 25...261 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards §...

2010-10-01

38

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

Code of Federal Regulations, 2011 CFR

...Network Operations in the Fixed Satellite Service (FSS) Bands. 25...261 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards §...

2011-10-01

39

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

Code of Federal Regulations, 2012 CFR

...Network Operations in the Fixed Satellite Service (FSS) Bands. 25...261 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards §...

2012-10-01

40

Surface albedo based on geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Surface albedo is the fraction of incoming solar radiation reflected by the land surface, and therefore is a sensitive indicator of environmental changes. To this end, surface albedo is identified as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). NOAA's National Climatic Data Center (NCDC) is implementing the Geostationary Surface Albedo (GSA; Lattanzio and Govaerts, 2010) algorithm for GOES data in support of an activity of the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM). SCOPE-CM helps coordinate ECV production responding to GCOS, WMO, and CEOS goals. The GSA algorithm was developed jointly by EUMETSAT and Joint Research Centre (JRC) using a method proposed by Pinty et al. (2000) to retrieve surface albedo by processing day-time, cloud-free geostationary observations from a single visible band. Currently, the GSA algorithm generates products operationally at EUMETSAT using geostationary data from satellites at 0° and 63°E and at JMA using 140°E geostationary data. To support development of an aggregate global albedo product, NCDC will apply the GSA algorithm to data from GOES-E (75°W) and GOES-W (135°W). For the GOES implementation, raw GOES observations are calibrated against AVHRR reflectance data available in PATMOS-x. Surface angular anisotropy is then determined through the inversion of the GSA radiative transfer model using multiple geostationary images collected over a day under different illumination conditions. The inversion process additionally requires ancillary total column ozone and water vapor values, which for the GOES implementation are acquired from the 20th Century Reanalysis V2 data set provided by the NOAA/OAR/ESRL PSD. The GSA algorithm produces a 10-day composite surface albedo map. This product will initially be developed for the period 2000-2003. Later, it will be applied to the complete GOES data collection (1978-present) as part of NOAA's Climate Data Record Program.

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

2011-12-01

41

Ionospheric scintillations of geostationary satellite radio waves  

Microsoft Academic Search

Observations of the scintillations associated with the major geomagnetic storms occurring on July 14 and September 7, 1982 are described. On July 14, relatively weak and long-lasting scintillations were observed on 136-MHz radio wave from the geostationary satellite, ETS-II. These scintillations have features somewhat different from those under geomagnetically quiet conditions: (1) they appeared at local times between 0 h

H. Kumagai; T. Ogawa; T. Hori

1986-01-01

42

Local oscillator distribution using a geostationary satellite  

NASA Technical Reports Server (NTRS)

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

Bardin, Joseph; Weinreb, Sander; Bagri, Durga

2004-01-01

43

Interpretation of Spectrometric Measurements of Active Geostationary Satellites  

NASA Astrophysics Data System (ADS)

Over 5000 visible near-infrared (VNIR) spectrometric measurements of active geostationary satellites have been collected with the National Research Council (NRC) 1.8m Plaskett telescope located at the Dominion Astrophysical Observatory (DAO) in Victoria, Canada. The objective of this ongoing experiment is to study how reflectance spectroscopy can be used to reliably identify specific material types on the surface of artificial Earth-orbiting objects. Active geostationary satellites were selected as the main subjects for this experiment since their orientation is stable and can be estimated to a high-level of confidence throughout a night of observation. Furthermore, for most geostationary satellites, there is a wide variety of sources that can provide some level of information as to their external surface composition. Notwithstanding the high number of measurements that have been collected to date, it was assumed that the experimenters would have a much greater success rate in material identification given the choice experimental subjects. To date, only the presence of aluminum has been confidently identified in some of the reflectance spectra that have been collected. Two additional material types, namely photovoltaic cells and polyimide film, the first layer of multi-layer insulation (MLI), have also been possibly identified. However uncertainties in the reduced spectral measurements prevent any definitive conclusion with respect to these materials at this time. The surprising lack of results with respect to material identification have forced the experimenters to use other data interpretation methods to characterize the spectral scattering characteristics of the studied satellites. The results from this study have already led to improvements in the ways that reflectance spectra from spacecraft are collected and analysed. Equally important, the data interpretation techniques elaborated over the course of this experiment will also serve to increase the body of knowledge pertaining to the spectral characterization of artificial Earth-orbiting objects.

Bedard, D.; Wade, G.

2014-09-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

45

Geostationary Operational Environmental Satellite (GOES) Gyro Temperature Model  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

46

Remote sensing from geostationary orbit: GEO TROPSAT, a new concept for atmospheric remote sensing  

NASA Astrophysics Data System (ADS)

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

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

1997-12-01

47

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

48

Downburst Prediction Applications of Meteorological Geostationary Satellites  

E-print Network

A suite of products has been developed and evaluated to assess hazards presented by convective storm downbursts derived from the current generation of Geostationary Operational Environmental Satellite (GOES) (13-15). The existing suite of GOES downburst prediction products employs the GOES sounder to calculate risk based on conceptual models of favorable environmental profiles for convective downburst generation. A diagnostic nowcasting product, the Microburst Windspeed Potential Index (MWPI), is designed to infer attributes of a favorable downburst environment: 1) the presence of large convective available potential energy (CAPE), and 2) the presence of a surface-based or elevated mixed layer with a steep temperature lapse rate and vertical relative humidity gradient. These conditions foster intense convective downdrafts upon the interaction of sub-saturated air in the elevated or sub-cloud mixed layer with the storm precipitation core. This paper provides an updated assessment of the MWPI algorithm, present...

Pryor, Kenneth L

2014-01-01

49

Orbit analysis of a geostationary gravitational wave interferometer detector array  

E-print Network

We analyze the trajectories of three geostationary satellites forming the GEOstationary GRAvitational Wave Interferometer (GEOGRAWI)~\\cite{tinto}, a space-based laser interferometer mission aiming to detect and study gravitational radiation in the ($10^{-4} - 10$) Hz band. The combined effects of the gravity fields of the Earth, the Sun and the Moon make the three satellites deviate from their nominally stationary, equatorial and equilateral configuration. Since changes in the satellites relative distances and orientations could negatively affect the precision of the laser heterodyne measurements, we have derived the time-dependence of the inter-satellite distances and velocities, the variations of the polar angles made by the constellation's three arms with respect to a chosen reference frame, and the time changes of the triangle's enclosed angles. We find that, during the time between two consecutive station-keeping maneuvers (about two weeks), the relative variations of the inter-satellite distances do not exceed a value of $0.05$ percent, while the relative velocities between pairs of satellites remain smaller than about $0.7 \\ {\\rm m/s}$. In addition, we find the angles made by the arms of the triangle with the equatorial plane to be periodic functions of time whose amplitudes grow linearly with time; the maximum variations experienced by these angles as well as by those within the triangle remain smaller than $3$ arc-minutes, while the East-West angular variations of the three arms remain smaller than about $15$ arc-minutes during the two-weeks period. The relatively small variations of these orbit parameters result into a set of system functional and performance requirements that are less stringent than those characterizing an interplanetary mission.

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

2014-10-11

50

GeoSTAR - A Microwave Sounder for Geostationary Satellites  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

51

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

52

Time transfer using geostationary satellites: Implementation of a Kalman filter  

NASA Technical Reports Server (NTRS)

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

Meyer, F.

1994-01-01

53

Radar for Monitoring Hurricanes from Geostationary Orbit  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

54

Downburst prediction applications of meteorological geostationary satellites  

NASA Astrophysics Data System (ADS)

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

Pryor, Kenneth L.

2014-11-01

55

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.

56

High Speed Internet Access Through Unidirectional Geostationary Satellite Channels  

E-print Network

. Communication over satellite links is often characterized by sporadic high bit-error rates and burst lossesHigh Speed Internet Access Through Unidirectional Geostationary Satellite Channels Ina Minei Reuven user to a direct satellite channel, at a speed 20 times faster than that of an average telephone modem

Cohen, Reuven

57

Crew Transfer Options for Servicing of Geostationary Satellites  

NASA Technical Reports Server (NTRS)

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

Cerro, Jeffrey A.

2012-01-01

58

Orbit determination for ISRO satellite missions  

NASA Astrophysics Data System (ADS)

Indian Space Research Organisation (ISRO) has been successful in using the in-house developed orbit determination and prediction software for satellite missions of Bhaskara, Rohini and APPLE. Considering the requirements of satellite missions, software packages are developed, tested and their accuracies are assessed. Orbit determination packages developed are SOIP, for low earth orbits of Bhaskara and Rohini missions, ORIGIN and ODPM, for orbits related to all phases of geo-stationary missions and SEGNIP, for drift and geo-stationary orbits. Software is tested and qualified using tracking data of SIGNE-3, D5-B, OTS, SYMPHONIE satellites with the help of software available with CNES, ESA and DFVLR. The results match well with those available from these agencies. These packages have supported orbit determination successfully throughout the mission life for all ISRO satellite missions. Member-Secretary

Rao, Ch. Sreehari; Sinha, S. K.

59

Performance Analysis of the HTTP Protocol on Geostationary Satellite Links  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

60

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

61

Ka-band geostationary satellite spacing requirements and access schemes  

NASA Technical Reports Server (NTRS)

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

Caron, Mario; Hindson, Daniel J.

1995-01-01

62

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

NASA Astrophysics Data System (ADS)

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

Kim, Dae-Sun; Lee, Yang-Won

2014-10-01

63

The Proposed Ku-Band Non Geostationary Communication Satellite Systems  

NASA Astrophysics Data System (ADS)

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

Evans, J. V.

2000-07-01

64

Air Quality Science and Regulatory Efforts Require Geostationary Satellite Measurements  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

65

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

NASA Technical Reports Server (NTRS)

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

Brousse, Pascal; Desprairies, Arnaud

1993-01-01

66

Land surface albedo based on GOES geostationary satellite observations  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

67

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

68

Hybrid system of communication and radio determination using two geostationary satellites  

NASA Technical Reports Server (NTRS)

A new hybrid satellite system which can provide both communications and positioning services in one system using two geostationary satellites is discussed. The distinctive feature is that location information can be provided by transmitting and receiving ranging signals over the same channel as communications through two geostationary satellites.

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

1990-01-01

69

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

70

CNES organization for station positioning of geostationary satellites  

NASA Technical Reports Server (NTRS)

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

Dulac, Jean

1993-01-01

71

The Geostationary Operational Environmental Satellite (GOES) Product Generation System  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

72

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

73

Satellite orbit predictor  

NASA Technical Reports Server (NTRS)

An analog aid to determine satellite coverage of Emergency Locator Transmitters Emergency Position Indicating Radio Beacon (ELT/EPIRB) distress incidence is discussed. The satellite orbit predictor is a graphical aid for determining the relationship between the satellite orbit, antenna coverage of the spacecraft and coverage of the Local User Terminal. The predictor allows the user to quickly visualize if a selected position will probably be detected and is composed of a base map and a satellite track overlay for each satellite.A table of equator crossings for each satellite is included.

Friedman, Morton l.; Garrett, James, Major

74

Investigation of water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

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

Velden, Christopher

1993-01-01

75

A study of regional-scale variability of in situ and model-generated tropospheric trace gases: Insights into observational requirements for a satellite in geostationary orbit  

NASA Astrophysics Data System (ADS)

We examine the results from a regional-scale chemical-transport model with 4-km resolution to determine the spatial variability of trace gases on this scale. Model-derived variability statistics are generated using 1st-order structure functions and then compared with in situ trace gas measurements from a series of aircraft campaigns. The variability of the observations and the model-derived concentrations are found to be in reasonable agreement for O 3 and CO, but the model underestimates the observed variability of NO 2. Variability statistics are then calculated for model-derived tropospheric column integrals. These integrals are calculated for 0-10 km (representative of the entire tropospheric column), 0-2 km (representative of the planetary boundary layer, PBL) and 2-10 km (representative of the free troposphere, FT). For each of the species examined, the variability of the tropospheric column is generally controlled by the variability in the lowest 2 km. The degree of control for each trace gas, however, is different. Whereas NO 2 is completely dominated by PBL processes, CO variability in the FT contributes appreciably to the variability of the entire tropospheric column, suggesting that two independent pieces of information for CO would be most helpful for describing the variability of the entire tropospheric column. Likewise, the variability of an independent free tropospheric measurement of O 3 would provide additional insight into the observed variability of the entire column, but the amount of additional information provided by a separate FT measurement is not as beneficial to what was found for CO. We provide additional analyses to quantify relationships that can be used to better understand the model-derived structure functions and their dependence on grid size and time of day. Lastly we present a practical example of how this information may be used for guidance in the development of science requirements for future satellite instruments since measurements from these instruments must be able to resolve smaller scale gradients to be used successfully for air quality applications.

Fishman, Jack; Silverman, Morgan L.; Crawford, James H.; Creilson, John K.

2011-09-01

76

A space robotic system used for on-orbit servicing in the Geostationary Orbit  

Microsoft Academic Search

The failures of GEO (Geostationary Orbit) spacecrafts will result in large economic cost and other bad impacts. In this paper, we propose a space robotic servicing concept, and present the design of the corresponding system. The system consists of a 7-DOF redundant manipulator, a 2-DOF docking mechanism, a set of stereo vision and general subsystems of a spacecraft platform. This

Wenfu Xu; Bin Liang; Dai Gao; Yangsheng Xu

2010-01-01

77

Differential spacecraft charging on the geostationary operational environmental satellites  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

78

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

NASA Astrophysics Data System (ADS)

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

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

79

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

Code of Federal Regulations, 2013 CFR

...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and...Safety and distress communications. Stations operating...non-geostationary mobile-satellite service that...

2013-10-01

80

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

Code of Federal Regulations, 2011 CFR

...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and...Safety and distress communications. Stations operating...non-geostationary mobile-satellite service that...

2011-10-01

81

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

Code of Federal Regulations, 2012 CFR

...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and...Safety and distress communications. Stations operating...non-geostationary mobile-satellite service that...

2012-10-01

82

Satellite orbit determination  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

83

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

84

Surface Solar Radiation from Geostationary Satellites for Renewable Energy  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

85

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

86

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

E-print Network

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

Lohmeyer, Whitney Quinne

2013-01-01

87

Investigation of water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

88

Theory of satellite orbit-orbit resonance  

Microsoft Academic Search

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

Leon Blitzer; John D. Anderson

1981-01-01

89

Relativistic electrons near geostationary orbit: Evidence for internal magnetospheric acceleration  

SciTech Connect

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

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

1989-06-01

90

47 CFR 25.145 - Licensing provisions for the Fixed-Satellite Service in the 20/30 GHz bands.  

Code of Federal Regulations, 2014 CFR

...identical non-geostationary satellite orbit satellites will be awarded a single...114, each non-geostationary satellite orbit applicant shall demonstrate the following...station into the previously-authorized orbit that is technically identical to...

2014-10-01

91

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

NASA Astrophysics Data System (ADS)

We study the potential of millimeter and sub-millimeter wavelengths for precipitation retrieval from geostationary sensors based on mesoscale cloud modeling and radiative transfer computation. Hydrometeor profiles simulated with the Meso-NH cloud resolving model for five European midlatitude situations are used to compute the brightness temperatures at frequencies from 23.8 to 875 GHz with the Atmospheric Transmission at Microwaves (ATM). Performances of both rain detection and rain rate retrieval are analyzed for different frequency sets, over ocean and land separately, and compared to the user requirements. The performances of a frequency set such as that already planned for geostationary satellites (with channels in the O2 lines at 50, 118, and 424 GHz, and in the H2O lines at 183, 325, 380 GHz) satisfy the requirements for Numerical Weather Prediction and NoWCasting in terms of rain detection as well as for rain rate retrieval above 1 mm/h. Suppressing the 50 GHz O2 channels does not seriously degrade the performances, except for rain rate below 1 mm/h, and, in addition, limits the spatial resolution problem from a geostationary orbit. Adding the thermal infrared observations has a limited impact. The retrieval of other hydrometeor quantities (cloud, ice) is also tested as well as the possibility to retrieve rain and the other hydrometeor profiles. These theoretical results are evaluated at close-to-millimeter wavelengths with coincident AMSU-B and radar observations (BALTEX and CAMRa). The results are degraded with respect to the theory, as expected, but are consistent with the observations.

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

2008-04-01

92

Analysis of signal to noise ratio for atmospheric ultraviolet remote sensing on geostationary orbit with variations of solar incident angles  

NASA Astrophysics Data System (ADS)

Ultraviolet (UV) sensors on a geostationary orbit (GEO) have important potential value in atmospheric remote sensing, but the satellites orbit mode of it is quit different from sun-synchronous orbit satellites, which result in the significant diurnal and seasonal variations in radiation environment of earth observation and radiation signal of sensors, therefore, the effect to sensor radiometric performance, such as signal to noise ratio for atmospheric ultraviolet remote sensing caused by variations of solar angle is significant in the performance design of sensors. The synthetic ultraviolet sensor is set at the geostationary orbit, 36000 km away from the sea level of the Equator with 8.75 degree field of view, and the subsatellite track point of which is located at 90 degrees east longitude and Equator. The Satellite scanning angles (SA) from 0 to 8.648 degree that cover the earth surface are selected corresponding to the 10 degrees equal interval view zenith angle, and the SA from 8.648 to 8.785 degree cover the earth lamb 100 km far away from earth tangent point. Based on the MODTRAN4 model, on normal atmospheric conditions, the distributions of the UV upwelling radiance from surface or limb viewing path of the earth could be simulated with the change of sun's right ascension. Moreover, the average signal to noise ratio to the atmospheric sounding is obtained in different UV spectra using the Sensor signal to noise ratio model. The results show that the thresholds range, tendency and shape of signal to noise ratio have a variety of features affected by variation of Sun hour angles and declinations. These result and conclusions could contribute to performance design of UV sensors on the geostationary orbit.

Lyu, Chun-guang; Yang, Wen-bo; Tian, Qing-jiu; Zhou, Yang; Liu, Zong-ming; Zhang, Han-mo

2014-11-01

93

An LO Phase Link Using a Commercial Geo-Stationary Satellite  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

94

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

Microsoft Academic Search

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

Gonzalo García; Luis Martín

95

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

96

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

E-print Network

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

Wood, Lloyd

97

Theory of satellite orbit-orbit resonance  

NASA Technical Reports Server (NTRS)

On the basis of the strong mathematical and physical parallels between orbit-orbit and spin-orbit resonances, the dynamics of mutual orbit perturbations between two satellites about a massive planet are examined, exploiting an approach previously adopted in the study of spin-orbit coupling. Resonances are found to exist when the mean orbital periods are commensurable with respect to some rotating axis, which condition also involves the apsidal and nodal motions of both satellites. In any resonant state the satellites are effectively trapped in separate potential wells, and a single variable is found to describe the simultaneous librations of both satellites. The librations in longitude are 180 deg out-of-phase, with fixed amplitude ratio that depends only on their relative masses and semimajor axes. The theory is applicable to Saturn's resonant pairs Titan-Hyperion and Mimas-Tethys, and in these cases the calculated libration periods are in reasonably good agreement with the observed periods.

Blitzer, L.; Anderson, J. D.

1981-01-01

98

Workshop on Satellites for Solar Energy Resource Information -Washington, DC, April 10-11, 1996 POTENTIALS OF IMAGES FROM GEOSTATIONARY SATELLITE DATA FOR THE  

E-print Network

Workshop on Satellites for Solar Energy Resource Information - Washington, DC, April 10-11, 1996 POTENTIALS OF IMAGES FROM GEOSTATIONARY SATELLITE DATA FOR THE ASSESSMENT OF SOLAR ENERGY PARAMETERS Lucien by meteorological geostationary satellites are currently used to map global radiation. Several methods exist which

Paris-Sud XI, Université de

99

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

NASA Astrophysics Data System (ADS)

The risk of collision of a geostationary satellite with uncontrolled debris or other satellites is currently estimated to be above 1% over the 13 years of a mission lifetime and has increased an order of magnitude in the last decade. Many geostationary satellite operators have started to control this risk in the last few years. GMV, a recognised leader in the field of Flight Dynamics, has a very extensive knowledge and broad base of experience in the field of space debris. This is due to its collaboration with the European Space Agency in this area over the last decade, as well as the development of customised solutions for operators such as EUTELSAT. At the beginning of 2003, GMV was awarded a contract by New Skies Satellites, a leading communications satellite operator based in The Hague, (The Netherlands), for the development of a customised tool for detection of close approaches between their satellites and third-party objects. This tool uses the information provided by USSTRATCOM as two-line elements (TLEs) plus the operational data available for the operator's satellites. The tool has eventually evolved into a generic product called focusCloseAp, which is commercialised like a COTS product in different versions, to provide operators with a cost-efficient solution for collision risk assessment. This paper presents the results of the experience obtained by New Skies Satellites while using focusCloseAp during the first year to obtain collision approach results automatically every night, the kind of problems encountered and the solutions that have been studied and / or applied. Some potential enhancements currently under consideration are also described. After running the program for 5 operational satellites during 5 months, 38 actual encounters have been found, yielding a trend of 1.5 encounters per month and satellite. focusCloseAp presents a great flexibility in its use and allows the user to modify the satellite orbital and manoeuvre parameters very easily and re-run different analysis cases to check the effects of the proposed modifications. This feature has been exploited at New Skies Satellites to find out that there are various options for altering the encounter geometry quite considerably. They will be presented in this paper. Moreover, when analysing the parameters altering the conjunction geometry, it has been found that a good planning of the operations is highly recommended to minimise the uncertainties. Differences between the planning and the actual operations can produce great variations of the geometry. Finally, the continuous use of TLEs has led to the detection of several problems that will be described in the paper along with the solutions that have been considered. Issues like precision of TLE propagation, sudden updates of TLEs inconsistent with previous sets and others are discussed.

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

100

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

101

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

102

Hybrid system of communication and positioning determination using two geostationary satellites  

NASA Astrophysics Data System (ADS)

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

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

1991-04-01

103

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

104

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

E-print Network

Ozone air quality measurement requirements for a geostationary satellite mission Peter Zoogman a Accepted 23 May 2011 Keywords: Air quality Ozone Kalman filter Assimilation Remote sensing a b s t r a c-CAPE geostationary air quality mission over North America. We consider instruments using different spec- tral

Chance, Kelly

105

Orbits R Us!  

NSDL National Science Digital Library

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

106

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

107

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

108

General relativity and satellite orbits  

NASA Technical Reports Server (NTRS)

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

Rubincam, D. P.

1975-01-01

109

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

NASA Technical Reports Server (NTRS)

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

Steadman, Karl

1989-01-01

110

Investigation of mesoscale meteorological phenomena as observed by geostationary satellite  

NASA Technical Reports Server (NTRS)

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

Brundidge, K. C.

1982-01-01

111

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

112

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

NASA Astrophysics Data System (ADS)

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

Gan, Q. B.

2012-07-01

113

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.

114

Low Earth orbit communications satellite  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

115

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

116

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

117

Scheme for detection of low clouds from geostationary weather satellite imagery  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

118

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

119

Lightning data study in conjunction with geostationary satellite data  

NASA Technical Reports Server (NTRS)

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

Auvine, Brian; Martin, David W.

1987-01-01

120

The orbit of Pluto's satellite  

NASA Technical Reports Server (NTRS)

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

Tholen, D. J.

1985-01-01

121

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

122

Upper-Tropospheric Winds Derived from Geostationary Satellite Water Vapor Observations  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

123

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

124

Goce Satellite Orbit Simulation and Study  

NASA Astrophysics Data System (ADS)

In the 2007 year the first Earth Explorer Core mission the Gravity Field and Steady - State Ocean Circulation Mission GOCE as a part of ESA s Living Planet Programme is planned The Earth s gravity field will be measured by the gradiometer put into the satellite board The selected orbit of this satellite is near circular at the mean altitude 250 km Our work contains the research of the simulated orbit of the GOCE satellite For the orbital computations the Cowell numerical integration of the eighth order was used The GOCE satellite orbit description includes the relative comparison of the various forces acting on the satellite For the satellite motion determination the geopotential was described by means of the EGM96 model Additionally the satellite accelerations due to the atmospheric drag the Moon gravity the Sun gravity the planet gravity the solid Earth tides the oceanic tides the direct solar radiation pressure the undirect reflected solar radiation pressure and the relativity were computed Besides the reference satellite orbit i e the orbit closed to the GOCE satellite planned orbit as much as possible the various variants of the satellite orbit were obtained The satellite motion in these orbital variants is affected or not affected by the chosen forces for example by the direct solar radiation pressure and the undirect reflected solar radiation pressure with respect to the satellite motion in the reference orbit To obtain the influence of the chosen forces on the GOCE satellite orbit the comparison between the reference orbit and the

Bobojc, A.; Drozyner, A.

125

An Orbiting Standards Platform for communication satellite system RF measurements  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

126

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

127

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

NASA Technical Reports Server (NTRS)

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

Lyatsky, Wladislaw; Khazanov, George V.

2008-01-01

128

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

129

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

NASA Astrophysics Data System (ADS)

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

Fang, Li

130

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

131

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

NASA Technical Reports Server (NTRS)

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

Ivancic, William D.

1992-01-01

132

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

Code of Federal Regulations, 2011 CFR

...frequencies allocated to the fixed-satellite service. 25.278 Section 25.278 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations §...

2011-10-01

133

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

Code of Federal Regulations, 2013 CFR

...frequencies allocated to the fixed-satellite service. 25.278 Section 25.278 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations §...

2013-10-01

134

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

Code of Federal Regulations, 2012 CFR

...frequencies allocated to the fixed-satellite service. 25.278 Section 25.278 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations §...

2012-10-01

135

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

Code of Federal Regulations, 2010 CFR

...frequencies allocated to the fixed-satellite service. 25.278 Section 25.278 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations §...

2010-10-01

136

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

Code of Federal Regulations, 2014 CFR

...frequencies allocated to the fixed-satellite service. 25.278 Section 25.278 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations §...

2014-10-01

137

Low earth orbit satellite/terrestrial mobile service compatibility  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

138

Most high-energy particle injections do not reach geostationary orbit  

NASA Astrophysics Data System (ADS)

The injection of high-energy particles into the inner magnetotail is often considered a reliable sign of a magnetic substorm. These injections are often thought to be caused by flow bursts, short-lived periods of narrow fast flow streams in the magnetotail. Analyzing records of flow bursts at the entry to the night-side inner magnetosphere, from 8 to 13 Earth radii, as seen by Geotail from 1995 to 2005, and by the Time History of Events and Macroscale Interactions During Substorms (THEMIS) satellite from 2008 to 2009, Sergeev et al. found that most flow bursts do not cause the injection of high-energy particles to geostationary altitudes, and thus such injections are a poor measure of substorm activity.

Schultz, Colin

2012-12-01

139

Coastal zone observations by a hyperspectral or multispectral imager in geostationary orbit  

NASA Astrophysics Data System (ADS)

Observations of coastal waters require high spectral and radiometric resolution, as compared to land, and high spatial resolution, as compared to the open ocean. An imaging instrument in geostationary orbit with a nominal aperture diameter of one meter in the spectral region from 400 - 1000 nm, ould meet these requirements on demand, over a large area of the Earth's surface. Observations made during daylight hours using filter wheel technology and large 2-D silicon focal plane arrays can achieve these objectives at reasonable coverage rates. Polarization-sensitive measurements would allow this instrument to optimize its observations of water-leaving radiance and to better compensate for atmospheric background. This instrument can be fabricated with existing technology.

Bremer, James C.; Maxwell, Marvin S.; Howard, Edward

2003-11-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

141

Nowcasting of peak lightning density using geostationary satellite data and model simulations  

NASA Astrophysics Data System (ADS)

As lightning poses dangers to both humans and industry, the ability to nowcast lightning initiation (LI) and extent is a formidable endeavor. The GOES-R Convective Initiation (CI) Algorithm provides 0-1 hr. nowcasts of both CI and LI, but gives no indication of lightning density. Through the use of geostationary satellite data, IR interest fields were analyzed leading up to convective storms that produced varying amounts of lightning, as observed by a Lightning Mapping Array. The goal was to determine if these interest fields could provide information on how much lightning future convection may produce. Lightning threat forecasts from the Weather Research and Forecasting (WRF) model were included to determine if these data provide any nowcast value. While data from higher flash density storms were limited, results indicated that trends unique to higher flash rate cases may exist. Furthermore, WRF output may provide a possible range of future flash density.

Saari, Matthew Dale William

142

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

NASA Astrophysics Data System (ADS)

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

Barabanova, Olga

2013-04-01

143

Linked Autonomous Interplanetary Satellite Orbit Navigation  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

144

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

145

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

146

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

147

GeoSTAR: Developing a Microwave Sounder for Geostationary Weather Satellites  

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

148

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-04-05

149

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

150

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

Microsoft Academic Search

Information on ultraviolet (UV) radiative fluxes is needed for public safety, understanding biodiversity, and for chemical transport modeling. Space-based observations can provide homogeneous and systematic estimates of the UV flux over large regions. In the past, UV flux estimates have been made from polar orbiting satellites; such estimates lack information on diurnal variability that can result in significant errors in

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

2008-01-01

151

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

Microsoft Academic Search

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

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

2005-01-01

152

Orbital subcycles for Earth remote sensing satellites  

Microsoft Academic Search

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

W. G. REES

1992-01-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

154

Design of the Flight Dynamics Subsystem for the COMS Satellite Ground Control System  

Microsoft Academic Search

A multi-mission geostationary Earth orbit satellite, Communications, Ocean, and Meteorological Satellite (COMS) has three payloads including Ka-band communications, geostationary ocean sensing imager, and meteorological imager. COMS Satellite Ground Control System (SGCS) is the only system for monitor and control of the satellite in orbit. In order to fulfill the mission operations of the three payloads and spacecraft bus, COMS SGCS

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

2007-01-01

155

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

NASA Astrophysics Data System (ADS)

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

Nishi, N.; Hamada, A.

2012-12-01

156

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

NASA Technical Reports Server (NTRS)

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

Bauer, Robert A.

2000-01-01

157

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

158

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

159

Aerodynamic lift effect on satellite orbits  

NASA Technical Reports Server (NTRS)

Numerical quadrature is employed to obtain orbit perturbation results from the general perturbation equations. Both aerodynamic lift and drag forces are included in the analysis of the satellite orbit. An exponential atmosphere with and without atmospheric rotation is used. A comparison is made of the perturbations which are caused by atmospheric rotation with those caused by satellite aerodynamic effects. Results indicate that aerodynamic lift effects on the semi-major axis and orbit inclination can be of the same order as the effects of atmosphere rotation depending upon the orientation of the lift vector. The results reveal the importance of including aerodynamic lift effects in orbit perturbation analysis.

Karr, G. R.; Cleland, J. G.; Devries, L. L.

1975-01-01

160

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

NASA Astrophysics Data System (ADS)

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

Kurino, T.

2012-12-01

161

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

NASA Astrophysics Data System (ADS)

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

Puca, S.; Porcu, F.; Rinollo, A.; Vulpiani, G.; Baguis, P.; Balabanova, S.; Campione, E.; Ertürk, A.; Gabellani, S.; Iwanski, R.; Jurašek, M.; Ka?ák, J.; Kerényi, J.; Koshinchanov, G.; Kozinarova, G.; Krahe, P.; Lapeta, B.; Lábó, E.; Milani, L.; Okon, L'.; Öztopal, A.; Pagliara, P.; Pignone, F.; Rachimow, C.; Rebora, N.; Roulin, E.; Sönmez, I.; Toniazzo, A.; Biron, D.; Casella, D.; Cattani, E.; Dietrich, S.; Di Paola, F.; Laviola, S.; Levizzani, V.; Melfi, D.; Mugnai, A.; Panegrossi, G.; Petracca, M.; Sanò, P.; Zauli, F.; Rosci, P.; De Leonibus, L.; Agosta, E.; Gattari, F.

2014-04-01

162

The Orbits of the Regular Jovian Satellites  

NASA Astrophysics Data System (ADS)

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

Jacobson, R.

2014-04-01

163

Goce Satellite Orbit Simulation and Study  

Microsoft Academic Search

In the 2007 year the first Earth Explorer Core mission the Gravity Field and Steady - State Ocean Circulation Mission GOCE as a part of ESA s Living Planet Programme is planned The Earth s gravity field will be measured by the gradiometer put into the satellite board The selected orbit of this satellite is near circular at the mean

A. Bobojc; A. Drozyner

2006-01-01

164

HORSESHOE PERIODIC ORBITS FOR SATURN COORBITAL SATELLITES  

E-print Network

HORSESHOE PERIODIC ORBITS FOR SATURN COORBITAL SATELLITES Jaume Llibre and Merc`e Oll'e Dept. Matem conclude that there exist stable horseshoe periodic orbits which fit with the motion of Saturn coorbital­ stricted problem. 1. Introduction In 1981 the successful Voyager flights to Saturn confirmed the existence

Politècnica de Catalunya, Universitat

165

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

PubMed Central

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

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

2013-01-01

166

PREDICT: Satellite tracking and orbital prediction  

NASA Astrophysics Data System (ADS)

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

Magliacane, John A.

2011-12-01

167

Lifetimes of lunar satellite orbits  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

168

GOCE Satellite Orbit in a Computational Aspect  

NASA Astrophysics Data System (ADS)

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

Bobojc, Andrzej; Drozyner, Andrzej

2013-04-01

169

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

NASA Technical Reports Server (NTRS)

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

1977-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

171

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

172

47 CFR 25.140 - Further requirements for license applications for geostationary space stations in the Fixed...  

Code of Federal Regulations, 2014 CFR

...Broadcasting-Satellite Service. (a) In addition to the information required by § 25.114, applicants for geostationary-orbit FSS space stations must provide an interference analysis to demonstrate the compatibility of their proposed system...

2014-10-01

173

History of on-orbit satellite fragmentations  

NASA Technical Reports Server (NTRS)

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

Nauer, David J.

1992-01-01

174

Orbit Design of Earth-Observation Satellite  

NASA Astrophysics Data System (ADS)

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

Owis, Ashraf

175

Exposure estimates for repair satellites at geosynchronous orbit  

NASA Astrophysics Data System (ADS)

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

Badavi, Francis F.

2013-02-01

176

The Orbits of the Inner Uranian Satellites  

NASA Astrophysics Data System (ADS)

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

Brozovic, Marina; Jacobson, R. A.

2009-05-01

177

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

NASA Technical Reports Server (NTRS)

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

Reinhart, E. E.

1974-01-01

178

Orbits of the six new satellites of Neptune  

Microsoft Academic Search

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,

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

1991-01-01

179

Comparison theorems, numerical integration and satellite orbits  

NASA Technical Reports Server (NTRS)

A comparison theorem estimating the difference between solutions of a perturbed and unperturbed equation is obtained. This is then applied to obtain error estimates in numerical integration problems, in particular, those problems involving computation of satellite orbits. The main result is a proof of the intuitive notion that the error in numerically integrating a stable equation grows less rapidly than for an unstable equation.

Stokes, A.

1975-01-01

180

Low Earth Orbit satellite traffic simulator  

NASA Technical Reports Server (NTRS)

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

Hoelzel, John

1995-01-01

181

History of on-orbit satellite fragmentations  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

182

A mission to preserve the geostationary region  

NASA Astrophysics Data System (ADS)

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 of risk posed at present and in the near future to GEO assets. It also investigates practical means for re-orbiting objects that can no longer be manoeuvred away from the operational GEO region by ground command.

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

2004-01-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

184

On the true circular orbit of a satellite  

NASA Astrophysics Data System (ADS)

The osculating orbit of a planetary satellite moving in the equatorial plane of the central body under the influence of a rotational symmetric perturbation force is elliptical in first order approximation even if the true orbit is always circular. The satellite motion is influenced by a resonance effect due to this perturbing force. An inclined true satellite orbit cannot be circular.

Jochim, E. F.; Eckstein, M. C.

1980-02-01

185

Cost competitive space transportation system for geostationary payloads  

NASA Technical Reports Server (NTRS)

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

Jones, C. R.

1976-01-01

186

A new method for determination of satellite orbits by transfer  

Microsoft Academic Search

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

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

2009-01-01

187

The Orbits of the Martian Satellites  

NASA Astrophysics Data System (ADS)

The original JPL ephemerides of the Martian satellites (Jacobson 1995, JPL IOM 312.1-95-142) were developed by fitting an analytical theory to the set of observations from 1877 to 1989. Since that time we have obtained Earthbased astrometry from the U. S. Naval Observatory (Pascu 2004, private comm.), Table Mountain Observatory (Owen 2003, private comm.), and LNA/MCT Observatory (Veiga 2008, A&A in press), and observations acquired by the MGS spacecraft (Bills et al. 2005, JGR 110, 1), by the Mars Express spacecraft (Oberst et al. 2006, A&A 447, 1145; Willner et al. 2008 A&A in press), and by the MRO spacecraft (Synnott 2006, private comm.). Our new orbits are based on numerical integration of the satellites' equations of motion. We take into account the mutual interactions of Phobos and Deimos, the perturbations due to the Earth, Moon, Jupiter, Saturn, and the Sun, the asphericity of Mars, the tide raised on Mars by Phobos, and the Phobos figure. We fit numerically integrated orbits to the complete set of observations. The fit determined not only the epoch states of the satellites but also the Martian tidal quality factor Q and the amplitude of the forced libration of Phobos.

Jacobson, Robert A.

2008-09-01

188

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

189

COSPAS-SARSAT Satellite Orbit Predictor. Volume 3  

NASA Technical Reports Server (NTRS)

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

Friedman, Morton L.; Garrett, James

1984-01-01

190

COSPAS-SARSAT Satellite Orbit Predictor Volume 10  

NASA Technical Reports Server (NTRS)

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

Friedman, Morton L.

1987-01-01

191

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

192

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

193

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

194

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

E-print Network

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

195

Decentralized determination of relative orbit for formation flying satellite  

Microsoft Academic Search

Autonomous formation flying is an important technology for the future space missions involving multiple satellites, and one of the key requirements of formation flying is accurate relative navigation. This paper develops an efficient approach of autonomous relative orbit determination for formation flying satellite. In view of that some formation flying satellites work at the orbits which are beyond the range

Dan Xue; Xibin Cao; Yunhua Wu

2006-01-01

196

APPLICATION OF OPTICAL TRACKING AND ORBIT ESTIMATION TO SATELLITE ORBIT TOMOGRAPHY  

E-print Network

AAS 13-824 APPLICATION OF OPTICAL TRACKING AND ORBIT ESTIMATION TO SATELLITE ORBIT TOMOGRAPHY Michael A. Shoemaker , Brendt Wohlberg , Richard Linares , and Josef Koller§ . Satellite orbit tomography, and selects nearly 200 resident space objects in low-Earth orbit as potential tracking targets. Over a chosen

Wohlberg, Brendt

197

Stereographic cloud heights from the imagery of two scan-synchronized geostationary satellites  

NASA Technical Reports Server (NTRS)

Scan synchronization of the sensors of two SMS-GOES satellites yields imagery from which cloud heights can be derived stereographically with a theoretical two-sigma random uncertainty of + or - 0.25 km for pairs of satellites separated by 60 degrees of longitude. Systematic height errors due to cloud motion can be kept below 100 m for all clouds with east-west components of speed below hurricane speed, provided the scan synchronization is within 40 seconds at the mid-point latitude, and the spin axis of each satellite is parallel to that of the earth.

Minzner, R. A.; Teagle, R. D.; Steranka, J.; Shenk, W. E.

1979-01-01

198

Jupiter orbiter lifetime: The hazard of Galilean satellite collision  

NASA Technical Reports Server (NTRS)

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

Friedlander, A. L.

1975-01-01

199

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

NASA Technical Reports Server (NTRS)

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

Velden, Christopher

1995-01-01

200

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.

201

Aqua satellite orbiting the Earth - Duration: 1:56.  

NASA Video Gallery

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

202

GEO/LEO satellites joint orbit determination based on satellite-to-satellite tracking  

NASA Astrophysics Data System (ADS)

TDRSS and Double Satellite Positioning System DSPS usually consist of two or three operational geosynchronous GEO satellites and a few customers LEO satellites The satellite-to-satellite tracking data provided by these systems put forward the requirement for multi-satellite joint orbit determination OD This paper will introduce the difference between OD with known GEO ephemeredes and OD with unknown GEO ephemeredes describe the measure model for sum of range observable and the difficulties on multi-satellite joint OD and examine the OD accuracy for the whole system The system including 2 GEOs 1 LEO and 3 ground stations tracking GEO is regarded as the standard mode for TDRSS or DSPS OD using the imitation observations on this mode indicates that GEO LEO satellites joint OD can achieve better positioning accuracy than LEO single satellite OD under the same measurement and force model error On the extreme mode 1 GEO 1 LEO 3 ground stations or 2 GEOs 1 LEO and 1 ground station the error on GEO satellite solar radiation force modeling is found to be decisive to the OD accuracy for the whole system On the constellation mode 2 GEOs N LEOs e g N 3 3 ground stations the accuracy of 5-satellite joint OD can get further improved compared with the standard 3-satellite OD mode

Wang, J. S.; Chen, J. R.; Wu, G. Y.; Li, J. S.; Chen, C. G.; Wang, Z. M.; Yang, K. Z.

203

The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites  

E-print Network

Available proper motion measurements of Milky Way (MW) satellite galaxies are used to calculate their orbital poles and projected uncertainties. These are compared to a set of recent cold dark-matter (CDM) simulations, tailored specifically to solve the MW satellite problem. We show that the CDM satellite orbital poles are fully consistent with being drawn from a random distribution, while the MW satellite orbital poles indicate that the disc-of-satellites of the Milky Way is rotationally supported. Furthermore, the bootstrapping analysis of the spatial distribution of theoretical CDM satellites also shows that they are consistent with being randomly drawn. The theoretical CDM satellite population thus shows a significantly different orbital and spatial distribution than the MW satellites, most probably indicating that the majority of the latter are of tidal origin rather than being DM dominated sub-structures. A statistic is presented that can be used to test a possible correlation of satellite galaxy orbits with their spatial distribution.

Manuel Metz; Pavel Kroupa; Noam I. Libeskind

2008-02-26

204

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

Microsoft Academic Search

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

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

1998-01-01

205

Estimation of net surface shortwave radiation over the tropical Indian Ocean using geostationary satellite observations: Algorithm and validation  

NASA Astrophysics Data System (ADS)

This paper presents the development of a methodology to estimate the net surface shortwave radiation (SWR) over tropical oceans using half-hourly geostationary satellite estimates of outgoing longwave radiation (OLR). The collocated data set of SWR measured at 13 buoy locations over the Indian Ocean and a Meteosat-derived OLR for the period of 2002-2009 have been used to derive an empirical relationship. The information from the solar zenith angle that determines the amount of solar radiation received at a particular location is used to normalize the SWR to nadir observation in order to make the empirical relationship location independent. As the relationship between SWR and OLR is valid mostly over the warm-pool regions, the present study restricts SWR estimation in the tropical Indian Ocean domain (30°E-110°E, 30°S-30°N). The SWR estimates are validated with an independent collocated data set and subsequently compared with the SWR estimates from the Global Energy and Water Cycle Experiment-Surface Radiation Budget V3.0 (GEWEX-SRB), International Satellite Cloud Climatology Project-Flux Data (ISCCP-FD), and National Centers for Environmental Prediction (NCEP) reanalysis for the year 2007. The present algorithm provides significantly better accuracy of SWR estimates, with a root-mean-square error of 27.3 W m-2 as compared with the values of 32.7, 37.5, and 59.6 W m-2 obtained from GEWEX-SRB, ISCCP-FD, and NCEP, respectively. The present algorithm also provides consistently better SWR compared with other available products under different sky conditions and seasons over Indian Ocean warm-pool regions.

Shahi, Naveen R.; Thapliyal, Pradeep K.; Sharma, Rashmi; Pal, Pradip K.; Sarkar, Abhijit

2011-09-01

206

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

207

Benefits of the use of Low Earth Orbit Satellites for some kind of services in developing countries  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to advise people of less industrialized countries about the possibilities and benefits of the application of Low Earth Orbit Satellites. A review of concepts contained on recent publications about LEO satellites, concerning technical characteristics, manufacture, launching and the type of signal they process will be given. Some projects of LEO constellations for future worldwide covering will be considered, with particular emphasis to the services they can provide. LEO satellites complement economically the services of geostationary satellites in various areas (information of position of vehicles onroute, monitoring the temperature of refrigerated transportation of fresh fruit, vegetables and other perishable products; measurement of physical magnitude of remotely located sensors; remote command operations, emergency alerts, etc).

Ciancaglini, Humberto R.

1993-10-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

209

Circumnutations of sunflower hypocotyls in satellite orbit  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

210

Satellite orbit and data sampling requirements  

NASA Technical Reports Server (NTRS)

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

Rossow, William

1993-01-01

211

Observation of Air Pollution and Climate Variables from Geostationary Orbit with SIRAS- G  

NASA Astrophysics Data System (ADS)

Understanding the impact of pollution on regional, continental, and global scales imposes unique challenges for spaceborne observations. The variability in tropospheric chemistry, source strengths, and transport results in sub-hourly temporal variation and produces small-scale variations in the vertical and horizontal distribution of key gases. Current spaceborne observations from low earth orbit have demonstrated the capability to measure key tropospheric trace gases from space but are limited to a twice daily observation. To improve on our understanding of diurnal variations requires observations from geosynchronous orbit. The Spaceborne Infrared Atmospheric Sounder from Geosynchronous Earth Orbit (SIRAS-G) being developed under the NASA Instrument Incubator Program (IIP) will enable high temporal, spatial and spectral resolution observations of temperature, water, ozone, aerosol, cloud and surface properties, and important trace gas concentrations such as CO, CH4, N2O and SO2. The spaceborne instrument concept measures thermal emission in 2048 spectral channels over the wavelength range from 3.75 to 15 microns with a nominal resolving power (?/?) of 1400. A laboratory demonstration instrument has been developed under IIP demonstrates the feasibility of the imaging grating spectrometer for this application. The constraints imposed on instrument mass, power and volume by a geosynchronous mission drives the instrument design toward more compact, and less complex optical systems. The system employs wide field-of-view hyperspectral infrared optical system that splits incoming radiation to separate grating spectrometer channels. Combined with large 2-D infrared detector arrays, this system provides simultaneous high-resolution spectral and spatial imaging over a large region with a nominal 4x4 km ground resolution.

Kampe, T.; Johnson, B.

2006-12-01

212

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

213

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

214

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

215

Huge "Structure" of Satellites Found Orbiting Milky Way  

E-print Network

Huge "Structure" of Satellites Found Orbiting Milky Way Grouping of galaxies puts cosmology A huge "structure" of satellite galaxies and star clusters has been found wheeling around the Milky Way the locations of the Milky Way's known satellites using sources ranging from 20th- century photographic plates

Belogay, Eugene A.

216

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

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

Jupiter orbiter lifetime - The hazard of Galilean satellite collision  

NASA Technical Reports Server (NTRS)

An assessment of the long-term collision risk is made for an uncontrolled orbiting spacecraft that repeatedly enters the spatial region occupied by the satellites. Numerical data are obtained for 50-year orbit propagations which account approximately for the major perturbative effects of Jupiter oblateness, solar gravity and satellite gravity. A broad statistical viewpoint regarding the question of collision likelihood is adopted and is based on a total sample size of 480 initial orbits distributed among 4 orbit classes, 8 inclinations and 15 initial epochs. Numerical results compare favorably with an analytical prediction formula which shows that eccentric low-inclination orbits have high collision probability.

Friedlander, A. L.

1975-01-01

219

Jupiter orbiter lifetime - The hazard of Galilean satellite collision  

NASA Technical Reports Server (NTRS)

An assessment of the long-term collision risk is made for an uncontrolled orbiting spacecraft that repeatedly enters the spatial region occupied by the satellites. Numerical data are obtained for 50-year orbit propagations which account approximately for the major perturbative effects of Jupiter oblateness, solar gravity and satellite gravity. A broad statistical viewpoint regarding the question of collision likelihood is adopted and is based on a total sample size of 480 initial orbits distributed among 4 orbit classes, 8 inclinations and 15 initial epochs. Numerical results compare favorably with an analytical prediction formula which shows that eccentric, low-inclination orbits have high collision probability.

Friedlander, A. L.

1975-01-01

220

DRAG COEFFICIENT ESTIMATION USING SATELLITE ATTITUDE AND ORBIT DATA  

E-print Network

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

Maroncelli, Mark

221

Orbit determination accuracies using satellite-to-satellite tracking  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

222

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

223

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

NASA Technical Reports Server (NTRS)

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

Pritchard, E. I.

1977-01-01

224

The Geostationary Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

225

The Geostationary Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

226

The Geostationary Fourier Transform Spectrometer  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

227

Determining the orbits of EGNOS satellites based on optical or microwave observations  

Microsoft Academic Search

The satellites of geostationary navigation overlay systems such as EGNOS (European Geostationary Navigation Overlay System) are equipped with single-frequency microwave transponders. The tracking data contain a GPS-like signal corresponding to the GPS C\\/A-code (Clear Access code) in the GPS L1-band of the electromagnetic spectrum. This signal is tracked by (some of the) commercially available GPS receivers and may be used

G. Beutler; U. Hugentobler; M. Ploner; M. Meindl; T. Schildknecht; C. Urschl

2005-01-01

228

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

229

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.

230

Method of resolving radio phase ambiguity in satellite orbit determination  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

231

Electric Propulsion for Low Earth Orbit Communication Satellites  

NASA Technical Reports Server (NTRS)

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

Oleson, Steven R.

1997-01-01

232

Development of a modular on-orbit serviceable satellite architecture  

Microsoft Academic Search

This paper describes an to develop an avionics architecture that enables replacement of deficient satellite hardware on-orbit as well as upgrade\\/adapt on-orbit systems. It is anticipated that routine, safe, and reliable spacecraft servicing will have significant payoff for many future types of science and military missions. The technologies that enable modern satellite servicing will therefore be critical for implementing new

Stephen A. Moynahan; Seamus Touhy

2001-01-01

233

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

Microsoft Academic Search

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

Francesco Vespe

2010-01-01

234

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

ERIC Educational Resources Information Center

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

Nous, Albert P.

235

Geostationary atmospheric infrared sounder: trace gases sensitivity  

NASA Astrophysics Data System (ADS)

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

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

1999-10-01

236

Temporary Changes in the Selected Accelerations and Orbital Elements for the GOCE Satellite Orbit  

NASA Astrophysics Data System (ADS)

The work contains the results of the GOCE satellite orbit simulation. The GOCE satellite orbit was presented by the temporary changes in selected accelerations and in selected orbital elements. The satellite accelerations due to: the geopotential, the Earth tides and the ocean tides (the radial component for both), the gravitation of the Moon, the gravitation of the Sun, the gravitation of the Venus and the relativity effects, are given. The showed changes in orbital elements include the semi-major axis, eccentricity, inclination, argument of perigee and right ascension of ascending node. Additionally, the changes in the satellite altitude were presented. For the orbit determination the Cowell numerical integration of the eighth order was used. In order to obtain the GOCE satellite orbit, the geopotential was described by means of the EGM96 model. The mentioned temporary changes in the selected accelerations and orbital elements were described. Most of them contain the characteristic periodic components, which are close to the satellite orbital period, the Earth's rotation period and the Moon's synodic period.

Boboj?, Andrzej

237

WARC and CCIR support for spectrum-orbit planning  

NASA Technical Reports Server (NTRS)

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

Sawitz, P. H.

1980-01-01

238

NOAA satellite programs and technology requirements  

NASA Technical Reports Server (NTRS)

Information concerning NOAA satellite programs is presented in vugraph form. The following topics are discussed: NOAA's space philosophy, the NESDIS FY-93 budget summary, LANDSAT program status, a history of geostationary satellites, the GOES program, current GOES instruments, improved GOES capabilities, polar orbiters, a history of TIROS R&D satellites, a history of ESSA operational satellites, a history of ITOS/NOAA satellites, and a history of TIROS-N/NOAA satellites.

Schneider, Stanley R.

1992-01-01

239

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

240

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

NASA Astrophysics Data System (ADS)

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

Showalter, Daniel J.; Black, Jonathan T.

2014-12-01

241

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

Technology Transfer Automated Retrieval System (TEKTRAN)

Thermal infrared (TIR) remote sensing of land-surface temperature (LST) provides valuable information about the sub-surface moisture status required for estimating evapotranspiration (ET) and detecting the onset and severity of drought. While empirical indices measuring anomalies in LST and vegetati...

242

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-03-08

243

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-03-08

244

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

NASA Astrophysics Data System (ADS)

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

Parks, Lisa Ann

245

Enhancing the Economics of Satellite Constellations via Staged Deployment and Orbital  

E-print Network

Enhancing the Economics of Satellite Constellations via Staged Deployment and Orbital Students #12;2 #12;Enhancing the Economics of Satellite Constellations via Staged Deployment and Orbital and Astronautics Abstract The "traditional" way of designing constellations of communications satellites

246

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

247

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

248

CASTOR: Cathode/Anode Satellite Thruster for Orbital Repositioning  

NASA Technical Reports Server (NTRS)

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

Mruphy, Gloria A.

2010-01-01

249

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

250

Tether de-orbiting of satellites at end of mission  

NASA Astrophysics Data System (ADS)

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

Sanmartin, Juan R.; Sánchez-Torres, Antonio

2012-07-01

251

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

Code of Federal Regulations, 2012 CFR

...259 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between NOAA meteorological satellite systems and non-voice,...

2012-10-01

252

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

Code of Federal Regulations, 2013 CFR

...259 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between NOAA meteorological satellite systems and non-voice,...

2013-10-01

253

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

Code of Federal Regulations, 2011 CFR

...259 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between NOAA meteorological satellite systems and non-voice,...

2011-10-01

254

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

Code of Federal Regulations, 2010 CFR

...259 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between NOAA meteorological satellite systems and non-voice,...

2010-10-01

255

Meteoroid and orbital debris risk mitigation in a low earth orbit satellite constellation  

Microsoft Academic Search

The NASA\\/JSC Hypervelocity Impact Technology Facility (HITF) performed a meteoroid and orbital debris threat assessment on a low earth orbit satellite constellation. The results of the analysis will show that the risk from hypervelocity impact was significant enough to warrant design changes. The techniques used to significantly mitigate the risk from hypervelocity impact will be discussed.

James L. Hyde; Eric L. Christiansen; Justin H. Kerr

2001-01-01

256

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

NASA Technical Reports Server (NTRS)

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

Paul, M. P.

1982-01-01

257

Orbits design for LEO space based solar power satellite system  

NASA Astrophysics Data System (ADS)

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

Addanki, Neelima Krishna Murthy

2011-12-01

258

On-Orbit Calibration of Satellite Gyroscopes  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

259

Geostationary Environment Monitoring Spectrometer (GEMS)  

NASA Astrophysics Data System (ADS)

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

Kim, Jhoon

260

Prototype development of a Geostationary Synthetic Thinned Aperture Radiometer, GeoSTAR  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

261

In-Space Transportation for GEO Space Solar Power Satellites  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

262

Communication Satellite Systems Conference, 11th, San Diego, CA, March 17-20, 1986, Technical Papers  

NASA Astrophysics Data System (ADS)

User-oriented satellite systems for the 1990's are considered along with a satellite system for aeronautical data communications, the colocation of geostationary communication satellites, an application of intersatellite links to domestic satellite systems, global interconnectivity in the next two decades, an analysis of the Geostar position determination system, and possible architectures for a European data relay satellite system. Attention is given to optimum antenna beam pointing for communication satellites, communications satellites versus fiber optics, spread spectrum-based synchronization of digital satellite transmissions, the Geostationary Satellite Orbit Analysis Program (GSOAP), technology achievements and projections for communication satellites of the future, and trends and development of low noise amplifiers using new FET device. Other topics explored are related to the Omninet mobile satellite system, the Space Transportation System, Japan's launch vehicles, the French military satellite system, and geostationary communications platform payload concepts.

1986-03-01

263

47 CFR 25.282 - Orbit raising maneuvers.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Orbit raising maneuvers. 25.282 Section...COMMUNICATIONS Technical Operations § 25.282 Orbit raising maneuvers. A space station...to operate in the geostationary satellite orbit under this part is also authorized...

2014-10-01

264

2A10Laser experiments for determining satellite orbits  

Microsoft Academic Search

The results from a series of experiments at the Smithsonian Astrophysical Observing Station, Organ Pass, N. Mex., indicate how lasers may be used to supplement the worldwide network of Baker-Nunn cameras in obtaining precise satellite orbits for geodesy and other purposes. A pulsed ruby laser and photoelectric receiver were located at the observing station. Laser returns were obtained from the

P. Anderson; C. Lehr; L. Maestre; G. Snyder

1966-01-01

265

Application and analysis of satellite orbit prediction techniques  

NASA Technical Reports Server (NTRS)

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

1977-01-01

266

Low earth orbit satellite based communication systems — Research opportunities  

Microsoft Academic Search

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

Bezalel Gavish

1997-01-01

267

Orbits of the small inner satellites of Jupiter  

NASA Technical Reports Server (NTRS)

Voyager images led to the discovery of the three small inner satellites of Jupiter, Adrastea, Metis, and Thebe. Attention is presently given to orbital parameter estimates and associated uncertainties that have been determined from Voyager imaging data, the achievable angular accuracy of which is about 0.00005 rad.

Synnott, S. P.

1984-01-01

268

Orbital performance of communication satellite microwave power amplifiers (MPAs)  

Microsoft Academic Search

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

R. Strauss

1993-01-01

269

Observations of orbital debris and satellites in Slovak Republic  

NASA Astrophysics Data System (ADS)

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

Silha, Jiri; Toth, Juraj

270

An Earth Orbiting Satellite Service and Repair Facility  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

271

Orbital Perturbations of the Galilean Satellites During Planetary Encounters  

E-print Network

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

Deienno, R; Vokrouhlicky, D; Yokoyama, T

2014-01-01

272

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

273

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

NASA Technical Reports Server (NTRS)

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

Pritchard, E. I.

1978-01-01

274

The Use of Resonant Orbits in Satellite Geodesy: A Review  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

275

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.

276

Control System and Flexible Satellite Interaction During Orbit Transfer Maneuver  

NASA Technical Reports Server (NTRS)

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

daSilva, Adenilson Roberto; GadelhadeSouza, Luiz Carlos

1998-01-01

277

NASA Now: Orbital Mechanics: Earth Observing Satellites - Duration: 6:03.  

NASA Video Gallery

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

278

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

279

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

Code of Federal Regulations, 2013 CFR

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

2013-10-01

280

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

NASA Technical Reports Server (NTRS)

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

Motamedi, Masoud; Estabrook, Polly

1990-01-01

281

Study of in-orbit test techniques for multibeam satellites  

NASA Astrophysics Data System (ADS)

Different approaches to the in orbit acceptance testing of a multibeam satellite are examined. The emphasis is on operational systems, and for guidance the system concept of the Advanced Multi-Beam On-Board-Switching (AMOS) satellite is used. For each cell there is an uplink beam and a downlink beam. All uplink beams are connected to the input side of a switch matrix, and all downlink beams are connected to the output side of the same switch matrix. The ability to connect every downlink beam to every uplink beam is available.

Lundquist, L.; Gough, R. A.

1983-04-01

282

Shuttle orbiter - IUS/DSP satellite interface contamination study  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

283

Cosmic ménage à trois: the origin of satellite galaxies on extreme orbits  

Microsoft Academic Search

We examine the orbits of satellite galaxies identified in a suite of N-body\\/gasdynamical simulations of the formation of L* galaxies in a Lambda cold dark matter universe. The numerical resolution of the simulations allows us to track in detail the orbits of the ~ 10 brightest satellites around each primary. Most satellites follow conventional orbits; after turning around, they accrete

Laura V. Sales; Julio F. Navarro; Mario G. Abadi; Matthias Steinmetz

2007-01-01

284

ORBITAL AND COLLISIONAL EVOLUTION OF THE IRREGULAR SATELLITES David Nesvorny,1  

E-print Network

ORBITAL AND COLLISIONAL EVOLUTION OF THE IRREGULAR SATELLITES David Nesvorny´,1 Jose L. A satellites, the irregular moons revolve around planets at large distances in tilted and eccentric orbits. Here we report a study of the orbital and collisional evolution of the irregular satellites from times

Nesvorny, David

285

Astrometry and Orbits of the Inner Satellites of Neptune  

NASA Astrophysics Data System (ADS)

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

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

1999-09-01

286

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

287

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

E-print Network

Aleksandar KOSTADINOV: Expected performance of Orbit Determination of the GALILEO Satellites satellite navigation system. The system will consist of about 30 satellites in medium earth orbits (MEOs) at 23600 km altitude. The launch of the first GALILEO satellites can be expected

Schuh, Harald

288

Practical use of an intermediate satellite's orbit. Formulas, programs, tests.  

NASA Astrophysics Data System (ADS)

All necessary materials for practical calculations of an intermediate satellite's orbit based on the (well-known) solution of the generalized problem of two fixed centers are presented. A summary of formulas, instructions of misprints in preceding publications, the estimation of the formulas precision on the basis of a comparison with results of numerical integration, Fortran texts for computational programs, directions to the programs and test examples are given. All the programs are adapted for BESM-6 and ES electronic computers.

Aksenov, E. P.; Emel'Yanov, N. V.; Tamarov, V. A.

289

Orbital Perturbations of the Galilean Satellites during Planetary Encounters  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

290

EUV observation from the Earth-orbiting satellite, EXCEED  

Microsoft Academic Search

An Earth-orbiting small satellite “EXtreme ultraviolet spectrosCope for ExosphEric Dynamics” (EXCEED) which will be launched in 2012 is under development. The mission will carry out spectroscopic and imaging observation of EUV (Extreme Ultraviolet: 60–145nm) emissions from tenuous plasmas around the planets (Venus, Mars, Mercury, and Jupiter). It is essential for EUV observation to put on an observing site outside the

K. Yoshioka; G. Murakami; I. Yoshikawa; M. Ueno; K. Uemizu; A. Yamazaki

2010-01-01

291

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

292

Reference crop evapotranspiration derived from geo-stationary satellite imagery - a case study for the Fogera flood plain, NW-Ethiopia and the Jordan Valley, Jordan  

NASA Astrophysics Data System (ADS)

First results are shown of a project aiming to estimate daily values of reference crop evapotranspiration ET0 from geo-stationary satellite imagery. In particular, for Woreta, a site in the Ethiopian highland at an elevation of about 1800 m, we tested a radiation-temperature based approximate formula proposed by Makkink (MAK) adopting ET0 evaluated with the version of the Penman-Monteith equation described in the FAO Irrigation and Drainage paper 56 as the most accurate estimate. More precisely we used the latter with measured daily solar radiation as input (denoted by PMFAO-Rs). Our data set for Woreta concerns a period where the surface was fully covered with short green non-stressed vegetation. Our project was carried out in the context of the Satellite Application Facility on Land Surface Analysis (LANDSAF) facility. Among others, the scope of LANDSAF is to increase benefit from the EUMETSAT Satellite Meteosat Second Generation (MSG). In this study we applied daily values of downward solar radiation at the surface obtained from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) radiometer. In addition, air temperature at 2 m was obtained from 3-hourly forecasts provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). Both MAK and PMFAO-Rs contain the psychrometric "constant", which is proportional to air pressure, which, in turn, decreases with elevation. In order to test elevation effects we tested MAK and its LANDSAF input data for 2 sites in the Jordan Valley located about 250 m b.s.l. Except for a small underestimation of air temperature at the Ethiopian site at 1800 m, the first results of our LANDSAF-ET0 project are promising. If our approach to derive ET0 proves successfully, then the LANDSAF will be able to initiate nearly real time free distribution of ET0 for the full MSG disk.

de Bruin, H. A. R.; Trigo, I. F.; Jitan, M. A.; Temesgen Enku, N.; van der Tol, C.; Gieske, A. S. M.

2010-07-01

293

Reference crop evapotranspiration derived from geo-stationary satellite imagery: a case study for the Fogera flood plain, NW-Ethiopia and the Jordan Valley, Jordan  

NASA Astrophysics Data System (ADS)

First results are shown of a project aiming to estimate daily values of reference crop evapotranspiration ET0 from geo-stationary satellite imagery. In particular, for Woreta, a site in the Ethiopian highland at an elevation of about 1800 m, we tested a radiation-temperature based approximate formula proposed by Makkink (MAK), adopting ET0 evaluated with the version of the Penman-Monteith equation described in the FAO Irrigation and Drainage paper 56 as the most accurate estimate. More precisely we used the latter with measured daily solar radiation as input (denoted by PMFAO-Rs). Our data set for Woreta concerns a period where the surface was fully covered with short green non-stressed vegetation. Our project was carried out in the context of the Satellite Application Facility on Land Surface Analysis (LANDSAF) facility. Among others, the scope of LANDSAF is to increase benefit from the EUMETSAT Satellite Meteosat Second Generation (MSG). In this study we applied daily values of downward solar radiation at the surface obtained from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) radiometer. In addition, air temperature at 2 m was obtained from 3-hourly forecasts provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). Both MAK and PMFAO-Rs contain the psychrometric "constant", which is proportional to air pressure, which, in turn, decreases with elevation. In order to test elevation effects we tested MAK and its LANDSAF input data for 2 sites in the Jordan Valley located about 250 m b.s.l. Except for a small underestimation of air temperature at the Ethiopian site at 1800 m, the first results of our LANDSAF-ET0 project are promising. If our approach to derive ET0 proves successfully, then the LANDSAF will be able to initiate nearly real time free distribution of ET0 for the full MSG disk.

de Bruin, H. A. R.; Trigo, I. F.; Jitan, M. A.; Temesgen Enku, N.; van der Tol, C.; Gieske, A. S. M.

2010-11-01

294

The enigma of the Uranian satellites' orbital eccentricities  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

295

Revisiting elliptical satellite orbits to enhance the O3b constellation  

E-print Network

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

Wood, Lloyd

296

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

Code of Federal Regulations, 2014 CFR

...f) (1), (2) and (3), as calculated for a fixed point on the Earth's surface in the plane of the space station's orbit, considering the worst-case frequency tolerance of all frequency determining components, and maximum positive and...

2014-10-01

297

Tracking target objects orbiting earth using satellite-based telescopes  

DOEpatents

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

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

2014-10-14

298

Geostationary Fourier Transform Spectrometer (GeoFTS)  

NASA Astrophysics Data System (ADS)

In order to confidently project the future evolution of climate and support efforts to mitigate the climate change, quantifying the emissions of CO2 and CH4 is a national and international priority. To accomplish this goal, new observational approaches are required that operate over spatial scales ranging from regional to global, and temporal scales from diurnal to decadal. Geostationary satellite observations of CO2, CH4 and correlative quantities such as CO and chlorophyll fluorescence provide a new measurement approach to deliver the quantity and quality of data needed for improved flux estimates and an improved understanding of the partitioning between biogenic and anthropogenic sources. GeoFTS is an exciting new concept that combines the game changing technology of imaging Fourier Transform Spectroscopy with the observational advantages of a geostationary orbit. The GeoFTS observations enable well-posed surface-atmospheric carbon exchange assessments as well as quantify the atmospheric signatures of anthropogenic CO2 and CH4 emissions. GeoFTS uses a single instrument to make measurements in the near-infrared spectral region at high spectral resolution. The imaging FTS measures atmospheric CO2, CH4, and CO to deliver high-resolution maps multiple times per day. A half-meter-sized cube, the instrument is designed to be a secondary "hosted" payload on a commercial GEO satellite. The instrument leverages recent NASA technology investments, uses a flight-proven interferometer and sensor chip assemblies, and requires no new technology development. NASA and other government agencies have adopted the hosted payload implementation approach because it substantially reduces the overall mission cost. Dense continuous mapping (4 km x 4 km pixels at 40 deg. latitude) is a transformational advance beyond, and complementary to, the capabilities of the NASA missions of record in low earth orbit, providing two to three orders of magnitude improvement in the number of observations over a third of the globe below 60 deg. latitude.

Sander, S. P.; Bekker, D. L.; Blavier, J. L.; Duren, R. M.; Eldering, A.; Frankenberg, C.; Key, R.; Manatt, K.; Miller, C. E.; Natraj, V.; Rider, D. M.; Wu, Y.

2012-12-01

299

Determination of the GOCE Satellite Orbit Sensitivity Under the Influence of Perturbing Forces  

NASA Astrophysics Data System (ADS)

The work contains the results of research into the simulated orbit of GOCE satellite. Satellite accelerations due to atmospheric drag, the gravitation of the Moon, the Sun, and the planets, the Earth tides, the ocean tides, the solar radiation pressure, the reflected solar radiation pressure and the relativity effects were computed. Besides the reference orbit (i.e. the orbit as close as possible to the GOCE planned orbit), the various variants of the satellite orbit (called the modified reference orbits - with different motion models) were obtained. The motion models contained the forces determining the satellite motion. For the orbital computations, the Cowell numerical integration of the eighths order was used. The geopotential was described by means of the EGM96 model. In order to obtain the influence of the aforementioned forces on the GOCE orbit, the percentage contributions of the accelerations due to these forces in the sum of all accelerations were computed. The maximum values of the mentioned accelerations were computed for the GOCE orbit variant with the motion model containing all forces given above. These values were compared with the measurement error of the linear accelerations by the GOCE satellite control system. The comparison between the reference orbit and the computed variants of the orbit was performed. In order to perform this comparison, the distances between the satellite position in the reference orbit and the satellite position in the given modified reference orbit (i.e. in a given orbit variant) were determined. These distances were compared with the total error of the GOCE satellite position determination. The orbital arc length, for which the selected forces can be neglected in the satellite motion model, were determined from this comparison. For these orbital arc lengths, the distance between the satellite position in the reference orbit and the satellite position in the given modified reference orbit is less or equal to the total error of the GOCE satellite position determination.

Boboj?, A.; Dro?yner

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

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

NASA Technical Reports Server (NTRS)

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

Velden, Christopher S.

1994-01-01

302

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

303

The orbits and masses of satellites of Pluto  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

304

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

Code of Federal Regulations, 2014 CFR

...angle of five degrees or more above the horizon. No NVNG MSS satellite shall transmit...with these restrictions. The ephemeris information must be updated system-wide on at...resolved expeditiously. This contact information must be made available to...

2014-10-01

305

The Effects of Solar Activity on the Orbital Evolution of Low Earth Orbiting Satellites  

NASA Astrophysics Data System (ADS)

Low altitude satellites (below 1000 km) are under the effect of the upper atmosphere drag. As it is well known, the upper atmosphere is strongly dependent on solar activity. Variations in atmospheric density are primarily influenced by variations in solar activity. Geomagnetic storms driven by solar flares are known to have significant effects on the total density of the upper atmosphere, especially, in the range 250-1000 km. The paper uses some results obtained at the Satellite Tracking Station No. 1132 of Cluj-Napoca Astronomical Observatory in the years elapsed from the launch of the first Earth's artificial satellite. We analyzed orbital evolutions of several satellites (e.g. SAMOS 2, Polyot 1, Explorer 19 and PAGEOS 1). The influence of flares and other short-duration solar events are examined. Historical remarks are pointed out.

Oproiu, Tiberiu; Chiruta, Ciprian

2007-03-01

306

Performance of a lightweight, low-cost geostationary X-band MILSATCOM  

NASA Astrophysics Data System (ADS)

The authors describe a payload concept for a new class of X-band satellites to supplement current X-band MILSATCOMs. The design exercise seeks to show that substantial communications capacity may be provided in a small, easily proliferated payload put into geostationary orbit to supplement existing and planned satellites without changing the ground segment. The concept presented is totally compatible with existing or near-term planned X-band satellites. Coverage, connectivity, carrier capacity, and a mass estimate for the payload concept are described.

Arnstein, D. S.; Brelian, I. K.

307

Transport Protocol and Resource Management for Satellite Networks: Framework of a Project  

E-print Network

of a satellite communications system. The protocol stack is based on the TCP/IP suite adapted to the channel proposed in the paper is mainly targeted to GEO (Geostationary Orbit) satellite communication systemsTransport Protocol and Resource Management for Satellite Networks: Framework of a Project Davide

Rossi, Michele

308

Spectral Analysis of the Selected Accelerations and Orbital Elements for the Goce Satellite Orbit  

NASA Astrophysics Data System (ADS)

The work contains the results of research of the simulated GOCE satellite orbit. For the 30-day orbit determination the Cowell numerical integration of the eighth order was used and the geopotential was described by means of the EGM96 model. The selected accelerations and the Keplerian elements were computed along this orbit. These accelerations included the satellite accelerations due to: the geopotential, the Earth tides and the ocean tides (the radial component for both), the gravitation of the Moon, the gravitation of the Sun, the gravitation of the Venus and the relativity effects. The computed accelerations and Keplerian elements were treated as the input data for the DFT algorithm (Discrete Fourier Transform) to determine their spectral characteristics, i.e. the amplitude power spectral densities (PSD). Additionally, the averages and standard deviations were obtained for the aforementioned accelerations and Keplerian elements. The numerous periodic components were identified. The characteristic resonances with the satellite orbital period, with the Earth's rotation period and with the Moon's synodic period were described.

Boboj?, Andrzej

2008-01-01

309

Orbital Tests of Relativistic Gravity using Artificial Satellites  

E-print Network

We reexamine non-Einsteinian effects observable in the orbital motion of low-orbit artificial Earth satellites. The motivations for doing so are twofold: (i) recent theoretical studies suggest that the correct theory of gravity might contain a scalar contribution which has been reduced to a small value by the effect of the cosmological expansion; (ii) presently developed space technologies should soon give access to a new generation of satellites endowed with drag-free systems and tracked in three dimensions at the centimeter level. Our analysis suggests that such data could measure two independent combinations of the Eddington parameters (beta - 1) and (gamma - 1) at the 10^-4 level and probe the time variability of Newton's "constant" at the d(ln G)/dt ~ 10^-13 yr^-1 level. These tests would provide well-needed complements to the results of the Lunar Laser Ranging experiment, and of the presently planned experiments aiming at measuring (gamma -1). In view of the strong demands they make on the level of non- gravitational perturbations, these tests might require a dedicated mission consisting of an optimized passive drag-free satellite.

Thibault Damour; Gilles Esposito-Farese

1994-03-28

310

A Low Earth Orbit satellite marine communication system demonstration  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

311

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

312

The Geostationary Atmospheric Sounder (GAS)  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

313

Satellite voice broadcast system study, volume 2  

NASA Technical Reports Server (NTRS)

This study investigates the feasibility of providing Voice of America (VOA) broadcasts by satellite relay, rather than via terrestrial relay stations. Satellite voice broadcast systems are described for three different frequency bands: HF (26 MHz), VHF (68 MHz), and L-band (1.5 GHz). The geographical areas of interest at HF and L-band include all major land masses worldwide with the exception of the U.S., Canada, and Australia. Geostationary satellite configurations are considered for both frequency bands. In addition, a system of subsynchronous, circular satellites with an orbit period of 8 hours is developed for the HF band. VHF broadcasts, which are confined to the Soviet Union, are provied by a system of Molniya satellites. Satellites intended for HF or VHF broadcastinbg are extremely large and heavy. Satellite designs presented here are limited in size and weight to the capability of the STS/Centaur launch vehicle combination. Even so, at HF it would take 47 geostationary satellites or 20 satellites in 8-hour orbits to fully satisfy the voice-channel requirements of the broadcast schedule provided by VOA. On the other hand, three Molniya satellites suffice for the geographically restricted schedule at VHF. At L-band, only four geostationary satellites are needed to meet the requirements of the complete broadcast schedule. Moreover, these satellites are comparable in size and weight to current satellites designed for direct broadcast of video program material.

Horstein, M.

1985-01-01

314

Communications satellite systems capacity analysis  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

315

The Principle of Navigation Constellation Composed of SIGSO Communication Satellites  

E-print Network

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

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

2012-01-01

316

GOES-R satellite solar panels ready for space  

NASA Astrophysics Data System (ADS)

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

Wendel, JoAnna

2014-07-01

317

Launch vehicles for communications satellites  

NASA Technical Reports Server (NTRS)

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

Mahon, J. B.

1982-01-01

318

Artificial Crater Formation on Satellite Surfaces Using an Orbiting Railgun  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

319

Aerodynamic Stability of Satellites in Elliptic Low Earth Orbits  

E-print Network

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

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

2013-01-01

320

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

NASA Astrophysics Data System (ADS)

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

Simmons, David R.

1990-10-01

321

Analysis of Errors in a Special Perturbations Satellite Orbit Propagator  

SciTech Connect

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

Beckerman, M.; Jones, J.P.

1999-02-01

322

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

323

Orbit Optimization and Scattering Coefficient Analysis for the Proposed GLORIA System  

NASA Technical Reports Server (NTRS)

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

Welch, Bryan

2004-01-01

324

STATIONARY CONFIGURATIONS FOR CO-ORBITAL SATELLITES WITH SMALL ARBITRARY MASSES  

E-print Network

STATIONARY CONFIGURATIONS FOR CO-ORBITAL SATELLITES WITH SMALL ARBITRARY MASSES STÃ?FAN RENNER results on the existence of stationary configurations for N co-orbital satellites with small but otherwise between the satellites, there always exists a set of masses (positive or negative) which achieves

Demoulin, Pascal

325

Astrometric observations of natural satellites and orbit update , Cheng X.1,2  

E-print Network

181 Astrometric observations of natural satellites and orbit update Xi X.J.1,2 , Cheng X.1 100039, China Abstract: This paper reports on our observing campaign of nature satellites and orbit research of photo plates. 1 Research History In 1985, we start our research on natural satellites

Paris-Sud XI, Université de

326

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

327

Satellite debris - Recent measurements  

NASA Technical Reports Server (NTRS)

More frequent reports concerning orbital debris damage to spacecraft have prompted the design, development and testing of equipment and techniques for the observation of moving objects by passive optical means. A consolidation is presently made of hundreds of hours of space debris observation, quantifying the numbers of small bodies in space relative to the actively watched artificial satellite population and estimating the numbers of detectable objects from near-earth orbit to geostationary orbit distances. The debris reported constitutes 11 times the tracked population in near-earth orbit and between 25 and 50 percent of the deep space population.

Taff, L. G.

1986-01-01

328

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

329

Orbit determination for a Jupiter orbiter tour of the Galilean satellites  

NASA Technical Reports Server (NTRS)

Current NASA planning envisions an ambitious Jupiter tour mission which will arrive at the planet in the year, 1984. The objectives of this mission are to broaden our knowledge of the outer solar system and in particular to extend our understanding of the physical processes at work in the Jupiter and Galilean satellite environment. To achieve these goals, precise spacecraft navigation is a fundamental requirement inasmuch as very near encounters with the satellites are necessary both for the planned scientific investigations and to reduce fuel requirements necessary for orbital insertion about the planet. This paper, deals with problems of producing precise spacecraft state estimates relative to the Galilean satellites, with the aid of both earth-based radio and on-board video data.

Russell, R. K.; Ellis, J.

1974-01-01

330

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

331

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

NASA Astrophysics Data System (ADS)

A cloud mask, cloud fractional coverage (CFC) and cloud top pressure (CTP) retrieval scheme called HelioFTH is presented. The algorithm relies on infrared (IR) window channel observations only. 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 high cloud coverage (HCC) from low level clouds. 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. Also, the HelioFTH HCC was inter-compared to CM SAF and ISCCP-DX over different regions. The probability of false detection of cloud-free HCC pixels is 15% lower for HelioFTH than for ISCCP-DX compared to the CM SAF HCC product over the full-disk area. HelioFTH could be used for generating a 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.

2013-02-01

332

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

333

The LAGEOS satellites orbit and Yukawa-like interactions  

NASA Astrophysics Data System (ADS)

Deviations from the gravitational inverse-square-law--as in the case of the hypothesised fifth (gravity-like) force--would lead to new weak interactions between macroscopic objects. These deviations from the usual 1/r law for the gravitational potential, and for masses separations ranging through several orders of magnitude, must be studied in order to derive if the supplementary interactions are consistent with Einstein equivalence principle, or instead break it, giving rise to new phenomena. Among the several techniques useful for the search of this additional physics to the various scales, the accurate measurements of the pericenter shift ? ? of binary systems may be used to test for a new-long-range-interaction (NLRI) with a characteristic range comparable with the system semimajor axis. These very weak NLRI are usually described by means of a Yukawa-like potential with strength ? and range ? . The LAGEOS satellites, thanks to the very accurate determination of their orbit through the powerful Satellite Laser Ranging (SLR) technique, could be considered the best candidates for the study of these NLRI. Indeed, the SLR technique tracks the orbit of the LAGEOS satellites with an accuracy approaching the cm value in range. We are then able to determine their orbital elements with about the same accuracy. In particular LAGEOS II pericenter, thanks to the higher orbital eccentricity e (about 0.014) with respect to LAGEOS (about 0.004), could be considered the best probe. Indeed, in the case of the pericenter the measurement quantity is ea? ? , with a the satellite semimajor axis (about 12,163 km). For instance, assuming that we are able to fit LAGEOS II orbit to a 3 cm level over 1 year, we obtain an estimate for the constraining of ? of about 8\\cdot 10-11 at a range ? of about 1 Earth radii. Of course, this estimate does not include the contributions from the systematic errors due to the various gravitational and non-gravitational perturbations, which are necessary to be considered in order to estimate an accurate error budget. In the present work we will focus on the constraints in ? that can be obtained with the actual gravity field solution EGM96 (? < 1.2\\cdot 10-10 from the even zonal harmonics uncertainties) and also with the first promising solutions from the CHAMP (? < 8.3\\cdot 10-11) and GRACE (? < 5.6\\cdot 10-11) missions. These results represent an improvement of two or three order-of-magnitude with respect to the best constraints obtained in the past with LAGEOS (? ? ? < 10-5-10-8). The impact of the non-gravitational perturbations mismodelling in the final error budget will be given together with the improvements obtainable in the constraint of the strength ? with the proposed LARES satellite, which will be characterised by a larger eccentricity with respect to LAGEOS II.

Lucchesi, D. M.

334

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

E-print Network

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

Michelson, David G.

335

The LAGEOS satellites orbit and Yukawa-like interactions  

NASA Astrophysics Data System (ADS)

LAGEOS II general relativity pericenter precession has been analysed in terms of the errors produced by the mismodelling of both the gravitational and non-gravitational perturbations acting on the satellite orbit. The accuracy in the pericenter determination may be considered as an upper-bound value for the estimate of the strength ? of a possible new-long-range-interaction described by a Yukawa-like potential. In the present work we have focused on the constraints in ? that can be obtained with the current best multi-satellites gravity field model EGM96 (? < 2.6 × 10-10) and also with the first promising models from the CHAMP (? < 1.8 × 10-10) and GRACE (? < 1.2 × 10-10) gravimetric missions. These results represent, potentially, an improvement of two or three orders-of-magnitude with respect to the best constraints obtained in the past with Earth-LAGEOS and Lunar-LAGEOS data (|?| < 10-5-10-8). The impact of the non-gravitational perturbations mismodelling in the final error budget has been determined together with the improvements obtainable in the constraint of the strength ? with the proposed LARES satellite.

Lucchesi, David M.

2011-04-01

336

Structured Control for a Satellites Platoon Formation in Low Earth Orbit Using Youla-Parametrization  

E-print Network

Structured Control for a Satellites Platoon Formation in Low Earth Orbit Using Youla synthesis is used to obtain a control law for a formation of two satellites. The control of a formation of four satellites, in the case of local measurements between each satellite and the preceding one, falls

337

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

338

GeoSTAR - A Synthetic Aperture Microwave Sounder for Geostationary Missions  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

339

Considering Orbit Changes for the Tracking and Data Relay Satellite System  

NASA Technical Reports Server (NTRS)

The possibility of a collision of a Tracking and Data Relay Satellite System (TDRSS) satellite with another orbiting object is a matter of concern to NASA. One hypothesis being investigated is that by slightly altering the TDRSS satellite orbits with changes to eccentricity and argument of perigee (AOP), the number of possible conjunctions between the TDRSS fleet members and other satellites and debris ur.ould decrease. This paper presents the results of analysis completed to hypothesis.

Dykes, Andy

2005-01-01

340

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

341

ENVIROSAT-2000 report: Federal agency satellite requirements  

NASA Technical Reports Server (NTRS)

The requirement of Federal agencies, other than NOAA, for the data and services of civil operational environmental satellites (both polar orbiting and geostationary) are summarized. Agency plans for taking advantage of proposed future Earth sensing space systems, domestic and foreign, are cited also. Current data uses and future requirements are addressed as identified by each agency.

Cotter, D. (editor); Wolzer, I. (editor); Blake, N.; Jarman, J.; Lichy, D.; Pangburn, T.; Mcardle, R.; Paul, C.; Shaffer, L.; Thorley, G.

1985-01-01

342

Satellite Communications in the 1980's.  

ERIC Educational Resources Information Center

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

Usunier, Pierre

343

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

344

Problem "13" for geostationary spacecraft  

NASA Astrophysics Data System (ADS)

We consider the problem of ensuring an energy balance of geostationary spacecraft (SCs) that will arise on October 13, 2015, during the long-duration eclipse of the solar disk visible from the SC by the Moon and the Earth. A technique for assessment of the eclipse duration, taking into account the shaded area of visible solar disk, is set forth, and results of calculating the eclipse conditions for different SC "stationary" points in the geostationary orbit are given. The data presented will allow the specialists to be prepared in advance for specific ballistic conditions of SC operation at this date and to plan operations to ensure the power balance of the SC power supply system during the prolonged shading of the Sun by the Moon and the Earth.

Nazarov, A. E.

2014-12-01

345

Spacecraft design project: Low Earth orbit communications satellite  

NASA Astrophysics Data System (ADS)

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

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

1991-12-01

346

Spacecraft design project: Low Earth orbit communications satellite  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

347

Estimating urban temperature bias using polar-orbiting satellite data  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

348

SPICE Module for the Satellite Orbit Analysis Program (SOAP)  

NASA Technical Reports Server (NTRS)

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

Coggi, John; Carnright, Robert; Hildebrand, Claude

2008-01-01

349

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

350

47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz Mobile-Satellite Service and 2 GHz Mobile-Satellite...  

Code of Federal Regulations, 2014 CFR

...angle of at least 5° at all times within the described geographic areas; and (iv) That a system only using geostationary orbit satellites, at a minimum, be capable of providing Mobile-Satellite Service on a continuous basis throughout the 50...

2014-10-01

351

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

NASA Technical Reports Server (NTRS)

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

1982-01-01

352

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

353

NAVSPASUR orbital processing for satellite break-up events  

NASA Technical Reports Server (NTRS)

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

Schumacher, Paul W., Jr.

1991-01-01

354

Expressions Module for the Satellite Orbit Analysis Program  

NASA Technical Reports Server (NTRS)

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

Edmonds, Karina

2008-01-01

355

The High-ORbit Ultraviolet-visible Satellite, HORUS  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

356

Scripting Module for the Satellite Orbit Analysis Program (SOAP)  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

357

Application of the Strong Scatter Theory to the Interpretation of Ionospheric Scintillation Measurements along Geostationary Satellite Links at VHF and L-band  

NASA Astrophysics Data System (ADS)

In a previous work, we demonstrated that ionospheric turbulence parameters may be inferred from amplitude scintillations well into in the strong scatter regime [Carrano et al., International Journal of Geophysics, 2012]. This technique, called Iterative Parameter Estimation (IPE), uses the strong scatter theory and numerical inversion to estimate the parameters of an ionospheric phase screen (turbulent intensity, phase spectral index, and irregularity zonal drift) consistent with the observed scintillations. The optimal screen parameters are determined such that the theoretical intensity spectrum on the ground best matches the measured intensity spectrum in a least squares sense. We use this technique to interpret scintillation measurements collected during a campaign at Ascension Island (7.96°S, 14.41°W) in March 2000, led by Santimay Basu and his collaborators from Air Force Research Laboratory. Geostationary satellites broadcasting radio signals at VHF and L-band were monitored along nearly co-linear links, enabling a multi-frequency analysis of scintillations with the same propagation geometry. The VHF data were acquired using antennas spaced in the magnetic east-west direction, which enabled direct measurement of the zonal irregularity drift. We show that IPE analysis of the VHF and L-Band scintillations, which exhibited very different statistics due to the wide frequency separation, yields similar estimates of the phase screen parameters that specify the disturbed ionospheric medium. This agreement provides confidence in our phase screen parameter estimates. It also suggests a technique for extrapolating scintillation measurements to frequencies other than those observed that is valid in the case of strong scatter. We find that IPE estimates of the zonal irregularity drift, made using scintillation observations along single space-to-ground link, are consistent with those measured independently using the spaced antenna technique. This encouraging result suggests one may measure the zonal irregularity drift at scintillation monitoring stations equipped with only a single channel receiver, so that the spaced-antenna technique cannot be employed. We noted that the scintillation index (S4) at L-band commonly exceeded that at VHF early in the evening when the irregularities were most intense, followed by one or more reversals of this trend at later local times as aging irregularities decayed and newly formed bubbles drifted over the station. We use the strong scatter theory to explain this perhaps counter-intuitive situation (one would normally expect a higher S4 at the lower frequency) in terms of strong refractive focusing.

Carrano, C. S.; Groves, K. M.; Basu, S.; Mackenzie, E.; Sheehan, R. E.

2013-12-01

358

Statistical and radiometric measurements of coherently illuminated, nonaugmented, low-earth-orbit satellites  

Microsoft Academic Search

The US Air Force Phillips Laboratory recently completed the Floodbeam Experiment (FBE), recording the first ever spatially resolved, coherent laser returns from non-augmented (non- retroreflectors), low earth orbit satellites. The experiment broadcast a near-IR, coherent laser at a selected set of low earth orbit satellites using a beam director and visible tracking system located at the Phillips Lab Starfire Optical

Douglas B. Rider; David G. Voelz; David H. Stone; Kathy J. Schulze; David R. Dean; Keith A. Bush

1994-01-01

359

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

360

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

361

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

362

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

NASA Technical Reports Server (NTRS)

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

Fuchs, A. J. (editor)

1979-01-01

363

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

NASA Astrophysics Data System (ADS)

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

Chao, C. C.

364

Energy integral method for gravity field determination from satellite orbit coordinates  

Microsoft Academic Search

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

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

2003-01-01

365

ORION: A Supersynchronous Transfer Orbit mission  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

366

ORION: A Supersynchronous Transfer Orbit mission  

NASA Astrophysics Data System (ADS)

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

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

1995-05-01

367

Retrieval of Moving Waves from Polar Orbiting Satellite Data  

NASA Astrophysics Data System (ADS)

The asynoptic nature of orbiting satellite data has presented difficulty in its interpolation. The estimation procedures developed by Kalman and Bucy provide a frame work for obtaining an optimal estimate at any given time of atmospheric field being measured. In the past, these procedures have incorporated atmospheric models consisting of stationary waves. The development and testing of a moving wave model (in which wave growth rate and phase speed are estimated in addition to wave amplitude and phase) is described in this dissertation. The moving wave model assumes the wave growth rate and phase speed are constant over a period of a few days. It uses the stationary wave model solution as the a priori information for linearizing the model equations. Simulated data sets, ranging from stationary waves to non-constant growing and moving waves, are used to test the algorithm. The potential of the improvement of solutions by iteration is tested and found unnecessary in most cases. The limitation of the estimation procedure on retrieving waves of nonconstant phase speeds and growth rates is also investigated. If the atmospheric situations are characterized by, or not far different from, constant growth and phase speed waves, much better retrieval of the wave is typically observed for the moving wave model, especially over periods of missing data.

Wey, Chowen Chou

368

Regenerative fuel cell study for satellites in GEO orbit  

NASA Technical Reports Server (NTRS)

Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. The first, the integrated design, utilized a configuration in which the fuel cell and electrolysis cells are alternately stacked inside a pressure vessel. Product water is transferred by diffusion during electrolysis and waste heat is conducted through the pressure wall, thus using completely passive means for transfer and control. The second alkaline system, the dedicated design, uses a separate fuel cell and electrolysis stack so that each unit can be optimized in size and weight based on its orbital operating period. The third design was a dual function stack configuration, in which each cell can operate in both fuel cell and electrolysis mode, thus eliminating the need for two separate stacks and associated equipment. Results indicate that using near term technology energy densities between 46 and 52 W-hr/lb can be achieved at efficiencies of 55 percent. System densities of 115 W-hr/lb are contemplated.

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

1987-01-01

369

Orbital performance of communication satellite microwave power amplifiers (MPAs)  

NASA Technical Reports Server (NTRS)

This paper presents background data on the performance of microwave power amplifiers (MPAs) used as transmitters in currently operating commercial communication satellites. Specifically aspects of two competing MPA types are discussed. These are well known TWTA (travelling wave tube amplifier) and the SSPA (solid state power amplifier). Extensive in-orbit data has been collected from over 2000 MPAs in 1991 and 1993. The study in 1991 invovlved 75 S/C (spacecraft) covering 463 S/C years. The 1993 'second-look' study encompassed a slightly different population of 72 S/C with 497 S/C years of operation. A surprising result of both studies was that SSPAs, although quite reliable, did not achieve the reliability of TWTAs were one-third more reliable in the 1993 study. This was at C-band with comparable power amplifiers, e.g. 6-16W of RF output power and similar gains. Data at K(sub u)-band is for TWTAs only since there are no SSPAs in the current S/C inventory. The other complementary result was that the projected failure rates used as S/C payload design guidelines were, on average, somewhat higher for TWTAs than the actual failure rates uncovered by this study. SSPA rates were as projected.

Strauss, R.

1993-01-01

370

EUV observation from the Earth-orbiting satellite, EXCEED  

NASA Astrophysics Data System (ADS)

An Earth-orbiting small satellite “EXtreme ultraviolet spectrosCope for ExosphEric Dynamics” (EXCEED) which will be launched in 2012 is under development. The mission will carry out spectroscopic and imaging observation of EUV (Extreme Ultraviolet: 60-145 nm) emissions from tenuous plasmas around the planets (Venus, Mars, Mercury, and Jupiter). It is essential for EUV observation to put on an observing site outside the Earth’s atmosphere to avoid the absorption. It is also essential that the detection efficiency must be very high in order to catch the faint signals from those targets. In this mission, we employ cesium iodide coated microchannel plate as a 2 dimensional photon counting devise which shows 1.5-50 times higher quantum detection efficiency comparing with the bared one. We coat the surface of the grating and entrance mirror with silicon carbides by the chemical vapor deposition method in order to archive the high diffraction efficiency and reflectivity. The whole spectrometer is shielded by the 2 mm thick stainless steel to prevent the contamination caused by the high energy electrons from the inner radiation belt. In this paper, we will introduce the mission overview, its instrument, and their performance.

Yoshioka, K.; Murakami, G.; Yoshikawa, I.; Ueno, M.; Uemizu, K.; Yamazaki, A.

2010-01-01

371

Developing the concept of a geostationary platform. [for communication services  

NASA Technical Reports Server (NTRS)

A geostationary platform concept with a proliferation of low-cost earth stations is discussed. Candidate platform concepts, servicing, life, and Orbital Transfer Vehicle (OTV) options are considered. A Life Cycle Costing model is used to select the minimum cost concept meeting program criteria. It is concluded that the geostationary platform concept is a practical and economical approach to providing expanding communication services within the limitations imposed by the available frequency spectrum and orbital arc.

Carey, W. T.; Bowman, R. M.; Stone, G. R.

1980-01-01

372

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

373

Introduction to satellite constellations orbital types, uses and related facts  

E-print Network

. #12;Tundra Useful highly elliptical orbits (HEO) Yellow circular GEO orbit shown for scale · Molnya (0.5sd ~12hr) and Tundra (~24hr 1sd orbits) ­ cover high latitudes at apogee. · Invented by Soviet) and Tundra (~24hr 1sd orbits) ­ cover high latitudes at apogee. · Invented by Soviet military; then Russian

Wood, Lloyd

374

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

NASA Astrophysics Data System (ADS)

In the context of the asteroid's danger problem, the determination of potentially the most dangerous orbits - the orbits of collision with the Earth - has a significant interest. One kind of orbit of collision is related with Lagrangian libration solution for the three body problem. It is known, that possible (temporary) capture to a satellite orbit from orbit near libration point. In case captured orbit has large inclination, it has very fast eccentricity evolution (increasing), leads to inevitable collision. It is not excepted, that object, caused ecological catastrophe 40 mln. years ago, and object push with the Earth on the border Mesozoic and Cenozoic era before the collision were move on of the Earth's satellite orbit. The example of this kind of orbit of collision is presented in this work.

Rosaev, A. E.

2002-11-01

375

NCAR's contribution to Improved tropospheric delay measurement and precision orbit determination for satellite ocean altimetry. 1 NCAR's contribution to  

E-print Network

NCAR's contribution to Improved tropospheric delay measurement and precision orbit determination orbit determination for satellite ocean altimetry. a JPL/NCAR project, Yoaz Bar-Sever, Principal and precision orbit determination for satellite ocean altimetry. 2 1.0 Introduction Satellite Oceanic altimetry

376

Prototype Development of a Geostationary Synthetic Thinned Aperture Radiometer, GeoSTAR  

NASA Technical Reports Server (NTRS)

Preliminary details of a 2-D synthetic aperture radiometer prototype operating from 50 to 58 GHz will be presented. The instrument is being developed as a laboratory testbed, and the goal of this work is to demonstrate the technologies needed to do atmospheric soundings with high spatial resolution from Geostationary orbit. The concept is to deploy a large sparse aperture Y-array from a geostationary satellite, and to use aperture synthesis to obtain images of the earth without the need for a large mechanically scanned antenna. The laboratory prototype consists of a Y-array of 24 horn antennas, MMIC receivers, and a digital cross-correlation sub-system. System studies are discussed, including an error budget which has been derived from numerical simulations. The error budget defines key requirements, such as null offsets, phase calibration, and antenna pattern knowledge. Details of the instrument design are discussed in the context of these requirements.

Tanner, Alan B.; Wilson, William J.; Kangaslahti, Pekka P.; Lambrigsten, Bjorn H.; Dinardo, Steven J.; Piepmeier, Jeffrey R.; Ruf, Christopher S.; Rogacki, Steven; Gross, S. M.; Musko, Steve

2004-01-01

377

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

378

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

379

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

380

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

381

Measurement of Atmospheric Composition from Geostationary Platforms  

NASA Technical Reports Server (NTRS)

Satellite instruments flown since 1970 have had great success in elucidating the processes that control stratospheric ozone. In contrast, space-based data for tropospheric constituents that affect air quality and climate have only recently become available. While these datasets highlight the rapidly advancing capabilities of spacebased tropospheric sensors, they are also pointing to the limitations of sun-synchronous, low-earth orbiting (SSO/LEO) satellite platforms for making such measurements. In our talk we will highlight the science requirements for new missions and the technological and algorithmic approaches that we are developing to meet these requirements. From these studies a clear need for advanced atmospheric composition sensors has emerged that can be put on geostationary (GEO) platforms to provide 5 km horizontal resolution with 15-60 minutes repeat cycle. Such measurements have been high priority in the recently released Decadal Survey report by the US National Research Council. The need for GEO is driven not only by the science requirements to track rapidly changing pollution events but also by the need to provide altitude-resolved information about tropospheric constituents. Currently, with the exception of aerosols, it is not possible to derive profile information about lower tropospheric constituents from satellite measurements. New algorithmic approaches are being developed to obtain this information by combining UV and IR data, by monitoring the spatial and temporal structures of the constituents, and by using low-level clouds to separate boundary layer constituents from free troposphere. All these approaches require better spatial and temporal resolution than that provided by LEO sensors.

Bhartia, P. K.; Kawa, S. R.; Janz, S.; Herman, J. R.; Gleason, J. F.

2008-01-01

382

The impact of orbital errors on the estimation of satellite clock errors and PPP  

NASA Astrophysics Data System (ADS)

Precise satellite orbit and clocks are essential for providing high accuracy real-time PPP (Precise Point Positioning) service. However, by treating the predicted orbits as fixed, the orbital errors may be partially assimilated by the estimated satellite clock and hence impact the positioning solutions. This paper presents the impact analysis of errors in radial and tangential orbital components on the estimation of satellite clocks and PPP through theoretical study and experimental evaluation. The relationship between the compensation of the orbital errors by the satellite clocks and the satellite-station geometry is discussed in details. Based on the satellite clocks estimated with regional station networks of different sizes (?100, ?300, ?500 and ?700 km in radius), results indicated that the orbital errors compensated by the satellite clock estimates reduce as the size of the network increases. An interesting regional PPP mode based on the broadcast ephemeris and the corresponding estimated satellite clocks is proposed and evaluated through the numerical study. The impact of orbital errors in the broadcast ephemeris has shown to be negligible for PPP users in a regional network of a radius of ?300 km, with positioning RMS of about 1.4, 1.4 and 3.7 cm for east, north and up component in the post-mission kinematic mode, comparable with 1.3, 1.3 and 3.6 cm using the precise orbits and the corresponding estimated clocks. Compared with the DGPS and RTK positioning, only the estimated satellite clocks are needed to be disseminated to PPP users for this approach. It can significantly alleviate the communication burdens and therefore can be beneficial to the real time applications.

Lou, Yidong; Zhang, Weixing; Wang, Charles; Yao, Xiuguang; Shi, Chuang; Liu, Jingnan

2014-10-01

383

The simulation of satellite tracking and orbit prediction considering the swaths  

NASA Astrophysics Data System (ADS)

A simulation system is developed for satellite tracking and orbit prediction. The program displays the location of Earth satellites and predicts the location of any satellite at any time. And the simulation of satellite tracking and orbit prediction take the swaths into consideration. The orbit prediction model and Two-Line Element (TLE) Sets are present first, and the Simplified General Perturbations Version 4 and Simplified Deep-space Perturbation Version 4 (SGP4/SDP4) orbit propagation algorithms are introduced then. In the end, we introduce how we build our system in detail. In the end we present the comparison of the prediction result between the system of ours and STK's. The result shows that SGP4/SDP4 are efficient and valid in our system.

Cai, Lei; Gong, Jianya

2008-10-01

384

On-orbit satellite inspection : navigation and [Delta]v analysis  

E-print Network

Since the late 1950's when the first man-made satellite was launched into space, there has been a keen interest to inspect these orbiting spacecraft. In the past, there have been employed a variety of inspection methods ...

Woffinden, David C., 1976-

2004-01-01

385

Experiment definition phase shuttle laboratory (LDRL-10.6 experiment): Shuttle sortie to elliptical orbit satellite  

NASA Technical Reports Server (NTRS)

The following topics were reviewed: (1) design options for shuttle terminal, (2) elliptical orbit satellite design options, (3) shuttle terminal details, (4) technology status and development requirements, (5) transmitter technology, and (6) carbon dioxide laser life studies.

Goodwin, F. E.; Nussmeier, T. A.; Stokes, L. S.; Vourgourakis, E. J.

1976-01-01

386

The Evolution of Spaceborne Microwave Sounders for the U.S. Polar-Orbiting Weather Satellites  

NASA Technical Reports Server (NTRS)

The Advanced Technology Microwave Sounder (ATMS) is the next generation space-borne microwave sounder. It is the latest and most advanced version of a series of satellite-based microwave sounders, currently under development by NASA for the future U.S. operational polar-orbiting weather satellite system, called the NPOESS (National Polar-orbiting Operational Environment Satellite System), slated to begin orbiting around the end of this decade. This paper will present a brief history of the evolution of the space-borne microwave sounders, from its early-day scientific experiments, through the operational sounder aboard today's polar orbiting weather satellites, and ending in the ATMS development. It will also describe the evolution of microwave radiometer technology that enabled the space-borne microwave radiometry, from its early versions with simple, nadir-viewing, fixed-horn antennas to the present-day scanning reflector antennas with broad-band MMIC Low Noise Amplifiers, plus on-board calibrations.

Shiue, James C.; Krimschansky, Sergey; Patel, Probodh; Hildebrand, Peter (Technical Monitor)

2002-01-01

387

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

Code of Federal Regulations, 2010 CFR

...260 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between DoD meteorological satellite systems and non-voice,...

2010-10-01

388

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

Code of Federal Regulations, 2012 CFR

...260 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between DoD meteorological satellite systems and non-voice,...

2012-10-01

389

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

Code of Federal Regulations, 2011 CFR

...260 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between DoD meteorological satellite systems and non-voice,...

2011-10-01

390

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

Code of Federal Regulations, 2013 CFR

...260 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...sharing between DoD meteorological satellite systems and non-voice,...

2013-10-01

391

Ground Experiment for Capturing Rotating Satellite in 3D Space Using an Orbit Maintenance Vehicle  

NASA Astrophysics Data System (ADS)

An orbit maintenance system equipped with a robot is expected to rescue satellites enabling their life spans to be prolonged and suppressing the amount of space debris. We are studying a system that is capable of the assembly, capture, diagnosis and repair of small satellites in orbit. A ground model of the orbit maintenance vehicle, which is equipped with a pair of robot arms, has been developed for these studies. In this paper, we describe a ground experiment for capturing an uncontrollably rotating satellite using the robot. The capture experiments were performed in sensor-dased autonomous control mode. We demonstrated that the vehicle flies toward the satellite, which is rotating in a test facility simulating 3-dimensional space, by measuring the relative position and attitude through image processing of a target marker, and then captures the handrail of the satellite with a hand having an adaptive mechanism by means of predictive visual servo tracking of the robot arm.

Machida, Kazuo; Ooi, Yoshitaka; Ozaki, Fumio

392

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.

2007-09-01

393

Geo-STAR: A Geostationary Microwave Sounder for the Future  

NASA Technical Reports Server (NTRS)

The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new Earth remote sensing instrument concept that has been under development at the Jet Propulsion Laboratory. First conceived in 1998 as a NASA New Millennium Program mission and subsequently developed in 2003-2006 as a proof-of-concept prototype under the NASA Instrument Incubator Program, it is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. The importance of such observations have been recognized by the National Academy of Sciences National Research Council, which recently released its report on a 'Decadal Survey' of NASA Earth Science activities1. One of the recommended missions for the next decade is a geostationary microwave sounder. GeoSTAR is well positioned to meet the requirements of such a mission, and because of the substantial investment NASA has already made in GeoSTAR technology development, this concept is fast approaching the necessary maturity for implementation in the next decade. NOAA is also keenly interested in GeoSTAR as a potential payload on its next series of geostationary weather satellites, the GOES-R series. GeoSTAR, with its ability to map out the three-dimensional structure of temperature, water vapor, clouds, precipitation and convective parameters on a continual basis, will significantly enhance our ability to observe hurricanes and other severe storms. In addition, with performance matching that of current and next generation of low-earth-orbiting microwave sounders, GeoSTAR will also provide observations important to the study of the hydrologic cycle, atmospheric processes and climate variability and trends. In particular, with GeoSTAR it will be possible to fully resolve the diurnal cycle. We discuss the GeoSTAR concept and basic design, the performance of the prototype, and a number of science applications that will be possible with GeoSTAR. The work reported on here was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.

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

2007-01-01

394

The National Polar-orbiting Operational Environmental Satellite System:Capabilities for Operational Land Remote Sensing  

Microsoft Academic Search

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)

C. W. Hoffman; S. Schneider; R. Murphy

2005-01-01

395

A software package for the graphical simulation of the Global Positioning System's satellite orbits  

E-print Network

A SOFTWARE PACKAGE FOR THE GRAPHICAL SIMULATION OF THE GLOBAL POSITIONING SYSTEM'S SATELLITE ORBITS A Thesis by EUGENIO MARTINEZ-LOPEZ Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE August 1981 Ma)or Subject: Electrical Engineering Copyright by Eugenio Martinez-Lopez, 1979 A SOFTWARE PACKAGE FOR THE GRAPHICAL SIMULATION OF THE GLOBAL POSITIONING SYSTEM&S SATELLITE ORBITS A Thesis by Eugenio...

Martinez-Lopez, Eugenio

2012-06-07

396

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

397

Introduction of the in-orbit test and its performance for the first meteorological imager of the Communication, Ocean, and Meteorological Satellite  

NASA Astrophysics Data System (ADS)

The first geostationary Earth observation satellite of Korea - the Communication, Ocean, and Meteorological Satellite (COMS) - was successfully launched on 27 June 2010. After arrival at its operational orbit, the satellite underwent an in-orbit test (IOT) that lasted for about 8 months. During the IOT period, the main payload for the weather application, the meteorological imager, went through successful tests for demonstrating its function and performance, and the test results are introduced here. The radiometric performance of the meteorological imager (MI) is tested by means of signal-to-noise ratio (SNR) for the visible channel, noise-equivalent differential temperature (NEdT) for the infrared channels, and pixel-to-pixel nonuniformity for both the visible and infrared channels. In the case of the visible channel, the SNR of all eight detectors is obtained using the ground-measured parameters with the background signals obtained in orbit. The overall performance shows a value larger than 26 at 5% albedo, exceeding the user requirement of 10 by a significant margin. Also, the relative variability of detector responsivity among the eight visible channels meets the user requirement, showing values within 10% of the user requirement. For the infrared channels, the NEdT of each detector is well within the user requirement and is comparable with or better than the legacy instruments, except for the water vapor channel, which is slightly noisier than the legacy instruments. The variability of detector responsivity of infrared channels is also below the user requirement, within 40% of the requirement, except for the shortwave infrared channel. The improved performance result is partly due to the stable and low detector temperature obtained due to spacecraft design, i.e., by installing a single solar panel on the opposite side of the MI.

Kim, D. H.; Ahn, M. H.

2014-08-01

398

The determination of the satellite orbit of Mariner 9.  

NASA Technical Reports Server (NTRS)

This paper presents a comprehensive analysis of the Mars orbital phase of the Mariner 9 trajectory as determined from Earth based radio data. Both the method and accuracy of the orbit determination process are reviewed. Analysis is presented to show the effects of Mars gravity model and node in the plane of the sky errors on the accuracy of orbit determination. In addition the long term evolution of the orbit from insertion to date is presented, and is decomposed into effects from the Mars gravity field, n-body perturbations, and solar radiation pressure. Since the orbit period is nearly commensurable with the Mars rotational period, the orbit experiences significant resonance perturbations. The primary perturbation is in-track with a maximum amplitude of 1000 km and a wavelength of 39 revolutions.

Born, G. H.; Christensen, E. J.; Ferrari, A. J.; Jordan, J. F.; Reinbold, S. J.

1972-01-01

399

Simulation and graphical representation of the orbit and the imaging parameter of Earth observation satellites  

Microsoft Academic Search

Synthetic aperture radar (SAR) satellites are widely used for Earth observation applications as weather conditions and cloudiness do not affect them. However, in order to be usable, data provided by those satellites need to be processed. This processing requires determination of imaging parameters that are closely linked to the spacecraft position and velocity on its orbit. For example, the difference

Jean-François Vandenrijt

2005-01-01

400

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

E-print Network

From Measurements to Models: What Satellite and Sub-Orbital Instruments Can and Must Contribute-location time series Regional Context R. Kahn #12;The NASA Earth Observing System's Terra Satellite ASTER First Products · Water & some Land · Globe ~ Every 2 days · ~ 10:30 AM & 1:30 PM Mid-vis AOT · Fine/Coarse Ratio

401

Autonomous determination of relative orbit for satellite formation flying using fault tolerant UKF  

Microsoft Academic Search

In the universe, the outliers always be included in the devices used for measuring on satellite, which affect the orthogonal property of Filter innovation sequence, filtering accuracy and make estimation inaccurate. In this paper, based on residual orthogonal UKF fault tolerant filtering method is used for autonomous determination of relative orbit for satellite formation flying, the outliers eliminating and instant

Wang Hui; Gu Xuemai

2009-01-01

402

Development of a surface isolation estimation technique suitable for application of polar orbiting satellite data  

NASA Technical Reports Server (NTRS)

A technique is developed for the estimation of total daily insolation on the basis of data derivable from operational polar-orbiting satellites. Although surface insolation and meteorological observations are used in the development, the algorithm is constrained in application by the infrequent daytime polar-orbiter coverage.

Davis, P. A.; Penn, L. M. (principal investigators)

1981-01-01

403

FSA-based link assignment and routing in low-earth orbit satellite networks  

Microsoft Academic Search

We propose a new framework for the link assignment (i.e., topological design) problem that arises from the use of intersatellite links (ISL's) in low-earth orbit (LEO) satellite networks. In the proposed framework, we model an LEO satellite network as a finite state automaton (FSA), where each state corresponds to an equal-length interval in the system period of the LEO satellite

Hong Seong Chang; Byoung Wan Kim; Chang Gun Lee; Sang Lyu Min; Yanghee Choi; Hyun Suk Yang; Doug Nyun Kim; Chong Sang Kim

1998-01-01

404

A new global Earth's gravity field model from satellite orbit perturbations: GRIM5-S1  

Microsoft Academic Search

A new model of the Earth's gravity field, called GRIM5-S1, was prepared in a joint German-French effort. The solution is based on satellite orbit perturbation analysis and exploits tracking data from 21 satellites to solve simultaneously for the gravitational and ocean tide potential and tracking station positions. The satellite-only solution results in a homogeneous representation of the geoid with an

Richard Biancale; Georges Balmino; Jean-Michel Lemoine; Jean-Charles Marty; Bernard Moynot; Francois Barlier; Pierre Exertier; Olivier Laurain; Pascal Gegout; Peter Schwintzer; Christoph Reigber; Albert Bode; Rolf König; Franz-Heinrich Massmann; Jean-Claude Raimondo; Roland Schmidt; Sheng Yuan Zhu

2000-01-01

405

Icy Satellites Impactor Probes for the Jovian Icy Moons Orbiter  

NASA Technical Reports Server (NTRS)

We present a preliminary design and mission description for Icy Satellites Impactor Probes (IPS). This design addresses two of the scientific themes of this Icy Galilean Satellites Forum: Surface Chemistry and Geophysics, and Interior Structures. Impactor probes may also make significant contributions in the areas of surface geology and mineralogy.

Shirley, J. H.; Zimmerman, W. F.; Strauss, W.; Ivlev, R.; Duong, T.; Hunter, D.; Slimko, E.; Nacaise, F.; Archer, E.; Nesmith, B.

2003-01-01

406

Simultaneous laser ranging and communication from an Earth-based satellite laser ranging station to the Lunar Reconnaissance Orbiter in lunar orbit  

E-print Network

We report a free space laser communication experiment from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit through the on board ...

Sun, Xiaoli

407

A BACK-UP ONBOARD ORBIT PROPAGATOR USING NEURAL NETWORK FOR SMALL SATELLITE MISSIONS  

Microsoft Academic Search

Various mission operations like tracking, imaging depend on orbit prediction. Presently, the most popular format is the 'Two-Line-Element (TLE)' (1) followed by NORAD. As a step towards autonomy, GPS receivers are used onboard a satellite for orbit information. As a back-up to GPS receiver, this paper addresses the feasibility of using a Neural Network for orbit prediction in terms of

Liu Fang; N. Nagarajan

408

Geometric improvement of the spot satellite orbit using Doris Doppler residual data  

NASA Astrophysics Data System (ADS)

After adjustment of a satellite orbit by classical dynamical methods, the residuals of tracking data from a Doppler satellite tracking network still contain information. They are used to further adjust geometrically the orbit, the station coordinates, and Doppler biases and drifts for each station. After extensive testing in simulation, the method is applied to 21 days of the DORIS data from the SPOT2 satellite. As this tracking network has an excellent coverage and a very low measurement noise, the orbit reproducibility in the tangential direction is reduced from 40-100 cm root-mean-squares (rms) with a classical dynamical orbit calculation to 7-32 cm rms for the geometrical orbit based on the difference between 2-day orbit arcs overlapping over 1 day. The reproducibility in the radial direction is slightly improved to 6-30 cm rms on the same arcs, with the most significant effect on the 1/revolution frequency. The formal error is also mostly reduced on this frequency. The Doppler residuals are reduced from 2-13 to 0.7-1.4 mm/s. This is only 3 times the measurement noise level and allows identification of ionospheric (magnetic storms), tropospheric (large atmospheric water vapor), and geometric effects (low elevation angles) in the data. Five-day orbit arcs of this improved orbit are used to recalculate station positions: A reproducibility of 4-13 cm is achieved on short distances (50 km), which is better than what is obtained with 15-day arcs of the initial dynamical orbit. Furthermore, for nine stations collocated with laser satellite tracking stations, the rms difference between their position calculated with 15 days of orbit and their independently estimated geodetic values is reduced from 56 cm rms with the dynamical orbit to 33 cm rms with the geometric orbit: This demonstrates that the improved reproducibility corresponds to an improved accuracy.

Fat, B. Nhun; Biancale, R.; Valette, J.-J.; Minster, J.-F.

1992-10-01

409

Advancement of Chinese Meteorological Feng-Yun (FY) and Oceanic Hai-Yang (HY) Satellite Remote Sensing  

Microsoft Academic Search

During recent decades, China has successfully launched several programs of satellite-borne remote sensing, including the meteorological Feng-Yun (FY, “wind cloud”) series and oceanic Hai-Yang (HY, “ocean”) series, in broad spectra, i.e., optical, infrared, and microwave. Since the initiation from the early 1970s, a total of nine meteorological satellites, FY series, including five polar-orbit satellites and four geostationary satellites, have been

Ya-Qiu Jin; Naimeng Lu; Minseng Lin

2010-01-01

410

Orbits  

NSDL National Science Digital Library

This Topic in Depth explores the Web's offerings on Orbits. The first site is offered by Northwestern University and asks: What is an orbit? (1 ). The site answers questions such as What causes an orbit to happen?, What is a satellite?, What travels in an orbit?, and Are there orbits within orbits?. A great starting site for this subject, visitors should come away with a broad and clear description of the topic. The second site, called Orbit Diagrams (2 ) is provided by the Harvard-Smithsonian Center for Astrophysics. The diagrams are "intended to aid in the visualization of the three-dimensional nature of the orbits and how they are orientated with respect to the orbit of the earth." Next, from the University of Wisconsin-Madison Department of Astronomy comes the Moon Phases (3 ) interactive Web site. Users are able to animate the moon's orbit in various phases and views as well as learn all the names of the phases. The fourth site is another virtual visualization tool provided by NASA's Near Earth Object Program called Orbits (4 ). The site lets users enter the designation or name of any asteroid or comet and then view the three-dimensional orbit of that object. The next site, maintained by the Conservation, Astronomy, Physics and Soaring Page, is called Satellite Orbits - Gravitational Assist from Planets (5 ). The site contains information on Kepler's Laws, which apply to elliptical orbits involving two bodies, hyperbolic orbits, relative motion, and the gravitational sphere of influence. The sixth site is an educational lesson provided by Dr. Richard L. Bowman of Bridgewater College called Planetary Orbit Exercise (6 ). Students are given information on Keplar's Laws of Planetary Motion, a list of definitions, links to outside sites for additional information, and then several questions to answer. The Planetary Physical Data (7 ) page is part of the larger Smithsonian Center for Earth and Planetary Studies Web site. Visitors will find a list of planets along with various information such as their relative sidereal period of orbit, mean orbital velocity, orbital eccentricity, and much more. The last site related to orbits is an educational activity provided by the Physics Classroom called Circular Motion and Planetary Motion (8 ). Four lessons are presented including Motion Characteristics for Circular Motion, Applications of Circular Motion, Universal Gravitation, and Planetary and Satellite Motion. Each contain clear and well written descriptions along with all the necessary information for successful completion.

Brieske, Joel A.

411

Experimental Program and Performance of Japan's Communication Satellite (CS) and Its First Results  

Microsoft Academic Search

Japan's CS spacecraft was launched successfully in December 1977 and placed at 135°E longitude in a geostationary orbit. On-orbit performance of the satellite was verified quite well with the exception of two sets ofK-band transponders. Substantial communication experiments have been conducted for more than half a year starting in May, 1978. In the satellite loop-back configuration at the Main Fixed

KEN-ICHI TSUKAMOTO; YUICHI OTSU; KATSUHIKO KOSAKA; TADASHI SHIOMI; HIDEICHI SASAOKA

1979-01-01

412

Cassini Orbit Determination Performance during Saturn Satellite Tour: August 2005 - January 2006  

NASA Technical Reports Server (NTRS)

During the period spanning the second Enceladus flyby in July 2005 through the eleventh Titan encounter in January 2006, the Cassini spacecraft was successfully navigated through eight close-targeted satellite encounters. Three of these encounters included the 500 km flybys of the icy satellites Hyperion, Dione and Rhea and five targeted flybys of Saturn's largest moon, Titan. This paper will show how our refinements to Saturn's satellite ephemerides have improved orbit determination predictions. These refinements include the mass estimates of Saturn and its satellites by better than 0.5%. Also, it will be shown how this better orbit determination performance has helped to eliminate several statistical maneuvers that were scheduled to clean-up orbit determination and/or maneuver-execution errors.

Antreasian, Peter G.; Bordi, J. J.; Criddle, K. E.; Ionasescu, R.; Jacobson, R. A.; Jones, J. B.; MacKenzie, R. A.; Parcher, D. W.; Pelletier, F. J.; Roth, D. C.; Stauch, J. R.

2007-01-01

413

Network Performance of Non-Geostationary Constellations Equipped With Intersatellite Links  

Microsoft Academic Search

An ideal, simplified, non-geostationary satellite constellation network, with varying numbers of intersatellite links on each satellite, is presented and analysed, using a minimum-path, circuit-switching approach.

Lloyd Wood

1995-01-01

414

Measurement of Satellite Impact Test Fragments for Modeling Orbital Debris  

NASA Technical Reports Server (NTRS)

There are over 13,000 pieces of catalogued objects 10cm and larger in orbit around Earth [ODQN, January 2009, p12]. More than 6000 of these objects are fragments from explosions and collisions. As the earth-orbiting object count increases, debris-generating collisions in the future become a statistical inevitability. To aid in understanding this collision risk, the NASA Orbital Debris Program Office has developed computer models that calculate quantity and orbits of debris both currently in orbit and in future epochs. In order to create a reasonable computer model of the orbital debris environment, it is important to understand the mechanics of creation of debris as a result of a collision. The measurement of the physical characteristics of debris resulting from ground-based, hypervelocity impact testing aids in understanding the sizes and shapes of debris produced from potential impacts in orbit. To advance the accuracy of fragment shape/size determination, the NASA Orbital Debris Program Office recently implemented a computerized measurement system. The goal of this system is to improve knowledge and understanding of the relation between commonly used dimensions and overall shape. The technique developed involves scanning a single fragment with a hand-held laser device, measuring its size properties using a sophisticated software tool, and creating a three-dimensional computer model to demonstrate how the object might appear in orbit. This information is used to aid optical techniques in shape determination. This more automated and repeatable method provides higher accuracy in the size and shape determination of debris.

Hill, Nicole M.

2009-01-01

415

Release Guidance Analysis of a Deputy Satellite Using Charged Formation Flying for On-Orbit Servicing  

NASA Astrophysics Data System (ADS)

On-orbit servicing is of interest for long duration missions due to potential benefits such as increasing the mission lifetime. In order to realize on-orbit servicing Coulomb, formation satellite systems lend themselves as one possible approach. This paper discusses such a system. A method is proposed for deploying a small deputy satellite from a docked condition on a main satellite to a Clohessy-Wiltshire bounded solution. A series of elliptical guidance paths are used for this purpose. Additionally, a method of changing the relative plane of motion of the deputy satellite is presented. This method requires the reorientation of the main satellite. Numerical simulations indicate that such maneuvers are possible within the given assumptions. It is observed that even in the worst-case scenario, positional errors can be kept within several centimeters.

Iliffe, Paul; Matunaga, Saburo

416

Nonlinear dynamics and simulation of multi-tethered satellite formations in Halo orbits  

NASA Astrophysics Data System (ADS)

The nonlinear coupling (not linearized) dynamics of multi-tethered satellite formations is presented, in which the parent satellite follows three-dimensional larger Halo orbits centered about the second libration point of the Sun-Earth system. We develop the dynamic model of system in Hill's problem. The system is arranged in a hub-spoke configuration (a main satellite in the hub and n tethers connecting n subsatellites to the hub in a spoke configuration). The numerical simulations of the coupling motion of the parent satellite and tether librations are carried out for a three-satellite case. The stability characteristics of the tethered formation is compared with that of the free formation in the same initial locations, and the free dynamics of spinning multi-tethered systems in the required larger Halo orbits is studied. The numerical results demonstrate that the different initial spinning rate and lengths of tethers have some impact on the stability of system.

Zhao, Jun; Cai, Zhiqin

2008-09-01

417

IMS/Satellite Situation Center report. Predicted orbit plots for IMP-H-1976. [Explorer 47 satellite  

NASA Technical Reports Server (NTRS)

Predicted orbit plots are shown in three projections. The time period covered by each set of projections is 12 days 6 hours, corresponding approximately to the period of IMP-H satellite. The three coordinate systems used are the Geocentric Solar Ecliptic system (GSE), the Geocentric Solar Magnetospheric system (GSM), and the Solar Magnetic system (SM). For each of the three projections, time ticks and codes are given on the satellite trajectories. The codes are interpreted in the table at the base of each plot. Time is given in the table as year/day/decimal hour. The total time covered by each plot is shown at the bottom of each table. An additional variable is given in the table for each time tick. For the GSM and SM projection this